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IF 5.5 4区医学 Q1 DERMATOLOGY

Journal Der Deutschen Dermatologischen Gesellschaft Pub Date : 2025-03-28 DOI:10.1111/ddg.15735_g

{"title":"Abstract","authors":"","doi":"10.1111/ddg.15735_g","DOIUrl":null,"url":null,"abstract":"Rupesh Paudel1,2*, Lena F Sorger1*, Anita Hufnagel1, Mira Pasemann1, Tamsanqa Hove1,3, André Marquardt1,4, Susanne Kneitz5, Andreas Schlosser6, Caroline Kisker3, Jochen Kuper3#, Svenja Meierjohann1,4#1Institute of Pathology, University of Würzburg, 97080 Würzburg, Germany2Department of Dermatology, Venereology and Allergology, University Hospital Würzburg, 97080 Würzburg, Germany.3Rudolf Virchow Center for Integrative and Translational Bioimaging, Institute for Structural Biology, University of Würzburg, 97080 Würzburg, Germany4Comprehensive Cancer Center Mainfranken, University of Würzburg, 97080 Würzburg, Germany5Department of Biochemistry and Cell Biology, University of Würzburg, 97074 Würzburg, Germany6Rudolf Virchow Center for Integrative and Translational Bioimaging, Mass Spectrometry Division, University of Würzburg, 97080 Würzburg, Germany#corresponding authors:J Kuper ([email protected])S Meierjohann ([email protected])*These authors contributed equally to this workAbstractGermline mutations in the DNA repair helicase XPD cause the diseases xeroderma pigmentosum (XP), trichothiodystrophy (TTD) and Cockayne syndrome. XP patients bear an increased risk of developing skin cancer including melanoma, even at young age. This is not observed for TTD patients despite DNA repair defects. To examine whether TTD cells harbor features counteracting tumorigenesis, we developed a TTD melanoma cell model containing the XPD variant R722W. Intriguingly, TTD melanoma cells exhibited reduced pro-tumorigenic features and an increased signature of the melanocyte lineage differentiation factor MITF, which went along with a strong basal upregulation of REDD2, an inhibitor of the mTOR/S6K/4EBP1 dependent protein translation machinery. REDD2 levels were partially driven by MITF, increased under UV exposure, and contributed to the reduced melanoma proliferation. To investigate whether similar processes are affected in melanocytes - the progenitor cell type of melanoma - we developed a TTD melanocyte model. Again, the MITF gene signature was increased, this time without affecting REDD2 expression. However, protein translation analyses revealed reduced ribosomal protein synthesis particularly in R722W melanocytes after UV stress, indicating a compromised protein translation machinery. Impaired protein translation was also demonstrated for the TTD XPD variant A725P, but not for the XPD variant D234N that causes XP. Concludingly, although effectors of R722W partially differ between melanoma cells and melanocytes, they result in translation inhibition and therefore reduced fitness, particularly under UV exposure. This may limit the probability of UV-driven tumorigenesis and offers an explanation why TTD patients do not develop melanomas.Gaia Veniali1, Anita Lombardi1, Massimo Teson2, Tiziana Nardo1, Elena Botta1, Elena Dell'Ambra2, Donata Orioli1, Manuela Lanzafame11CNR-Istituto di Genetica Molecolare, Pavia, Italy2Istituto Dermopatico dell'Immacolata (IDI), Rome, ItalyNucleotide Excision Repair (NER) is the only DNA repair system in humans dedicated to removing bulky DNA adducts induced by ultraviolet (UV) radiations. NER defects are responsible for the inherited disorder xeroderma pigmentosum (XP), which is characterized by high predisposition of developing melanoma and non-melanoma skin cancers due to the accumulation of unrepaired UV-induced DNA lesions. Interestingly, mutations in the NER-related genes XPB or XPD can also cause trichothiodystrophy (TTD), another rare disorder characterized by NER defects. However, unlike XP, TTD patients do not develop cancer but are characterized by hair abnormalities, pre- or post-natal growth failure, neurodevelopmental and neurological dysfunctions, signs of premature aging. Investigations and comparative gene expression profile studies on skin cells from XP and TTD patients carrying mutations in the same gene, offer a promising tool for identifying molecular pathways that drive or counteract skin carcinogenesis.Whole-transcriptome analysis has been performed on our collection of primary skin fibroblasts and keratinocytes from XPD-mutated patients. We found disease-specific expression signatures, with XP cells showing a tumor-like profile characterized by the upregulation of genes involved in inflammation and extracellular matrix remodeling, whereas TTD cells exhibit an anti-tumor signature marked by the upregulation of tumor suppressor genes and the downregulation of oncogenic pathways.The relevance of the identified transcription deregulations on skin cancer pathophysiology is currently under investigation by silencing or overexpressing the genes of interests in control skin cells and taking advantage of three-dimensional (3D) culture models that mimic critical aspects of solid cancers, including mechanical regulation of growth, hypoxia, and invasiveness. Our preliminary data on melanoma spheroids indicate that specific gene expression deregulations in the tumor microenvironment influence melanoma invasiveness.Overall, our findings indicate that XP and TTD patient-derived primary skin cells, sharing mutations in the same gene but exhibiting opposite skin cancer susceptibilities, provide an exceptional framework for uncovering the molecular mechanisms underlying skin carcinogenesis and identifying novel targets for therapeutic intervention.Ubiquitylation plays a crucial role in Nucleotide Excision Repair (NER). In the subpathway Global Genome NER (GG-NER), XPC detects lesions genome wide, with its activity enhanced after ubiquitylation by CRL4DDB2. Conversely, Transcription-Coupled NER (TC-NER) is restricted to the transcribed strand of active genes, initiated by recognition of the lesion-stalled RNA Polymerase II (RNAPII) by CSB and subsequent recruitment of CSA, the substrate recognition subunit of CRL4CSA. Ubiquitylation of RNAPII by CRL4CSA at lysine 1268 (K1268) of its RPB1 subunit was previously shown to be important for TC-NER. Moreover, RPB1 K1268 ubiquitylation suppresses global gene expression by inducing RPB1 degradation, lowering RNAPII levels.Intriguingly, however, cells defective in TC-NER still display robust RPB1 ubiquitylation after DNA damage but do not degrade RPB1. This led us to speculate that ubiquitylated RPB1 (ubi-RPB1) might have alternative, non-degradative roles. As ubi-RPB1 is only a small fraction of total RPB1 in the cell, we developed a strategy based on sequential enrichment steps followed by mass-spectrometry to study its interactome. For these experiments, we used an RPB1-K1268R mutant as a control to identify factors that specifically associate with ubiquitylated RPB1. This approach revealed a number of unexpected, high-confidence interactors, that led us to uncover a novel signaling pathway with major implications for Nucleotide Excision Repair.Debora Ferria,*, Giulia Brancaa,*, Manuela Lanzafamea, Erica Gandolfia, Valentina Rivaa, Giovanni Magaa, Claudia Landic, Luca Binic, Lavinia Arsenia, Fiorenzo A. Peveralia, Emmanuel Compeb and Donata OrioliaaIstituto di Genetica Molecolare (IGM) L.L. Cavalli Sforza, CNR, 27100 Pavia, Italy;bInstitut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Illkirch Cedex 67404, Strasbourg, France;cDepartment of Life Sciences, University of Siena, 53100 Siena, Italy.*Equal contributionAbstractThe transcription factor IIH (TFIIH) is a ten-subunits complex organized in two sub-complexes, the ternary CDK activating kinase (CAK) and the hexameric core-TFIIH, bridged together by the XPD subunit. TFIIH is involved in different cellular mechanisms such as basal transcription, gene expression regulation and nucleotide excision repair (NER), the DNA repair pathway that specifically removes the bulky DNA adducts induced by ultraviolet (UV) light or other genotoxic agents. Mutations in the ERCC2/XPD gene are responsible for different clinical conditions, including the cancer-prone xeroderma pigmentosum (XP) and the photosensitive form of trichothiodystrophy (PS-TTD), a cancer-free neurodevelopmental disorder. At the cellular level, all XPD mutations result in NER defects and accumulation of unrepaired DNA photolesions. Furthermore, mutations specifically associated to PS-TTD clinical features also lead to reduced TFIIH cellular amount and transcription deregulations. Recently, our laboratory has demonstrated that PS-TTD more than XP primary dermal fibroblasts suffer of wide transcriptional impairments that, in some cases, result in altered protein content contributing to PS-TTD clinical features. To accomplish its function in DNA repair and transcription, TFIIH requires a direct interaction with the chromatin and relies on the presence of both the CAK and core sub-complexes. In the present study, we investigate the impact of XPD mutations on the association/dissociation of the two sub-complexes and their interaction with the chromatin.Immunoprecipitation of the chromatin-bound CAK followed by mass spectrometry analysis identifies TFIIH as part of a large multiprotein assembly that assists RNA polymerase II during mRNA synthesis. PS-TTD causing mutations alter the relationships of TFIIH with other components of the protein assembly and give rise to transcriptional stress. Overall, this study sheds light on a still unknown function of TFIIH during transcription, whose impairment contributes to the wide transcriptional defects underlying PS-TTD pathological condition.Alexandra Paolino1, Ruth Keogh2, Sinéad M. Langan2, Alan R. Lehmann3, Isabel Garrood1, Hiva Fassihi11National Xeroderma Pigmentosum Service, Department of Photodermatology, St John's Institute of Dermatology, Guy's and St Thomas’ Foundation Trust, London SE1 7EH, United Kingdom.2 Department of Non-communicable Disease Epidemiology, London School of Hygiene and Tropical Medicine, London, WC1E 7HT, United Kingdom.3 Genome Damage and Stability Centre, University of Sussex, Falmer, Brighton BN1 9RQ, United Kingdom.Introduction: Xeroderma pigmentosum (XP) is a rare autosomal recessive disorder of DNA repair, characterized by extreme sensitivity to ultraviolet radiation. Patients are at risk of skin cancers, ocular surface disease, and approximately one-third of patients experience progressive neurodegeneration. Life expectancy varies significantly based on complementation group, disease severity, and access to preventive measures. Obtaining reliable survival estimates for this rare and genetically heterogeneous disease can be challenging, leading to variability in reported survival rates. A National Institutes of Health study of 106 patients (1971 to 2009) reported a median age at death of 29 years for XP patients with neurodegeneration and 37 years for those without (1). These statistics are frequently cited in academic literature and widely reported on publicly accessible websites.Aim: To assess the life expectancy of XP patients receiving multidisciplinary care at the UK National XP Service and assess patients and families understanding of their prognosis.Methods: We conducted a longitudinal study of 89 patients examined and treated annually in the UK National XP Service from 2015 to 2024. Mortality events were documented and categorised between those with and without neurodegeneration. To evaluate patient perceptions on life expectancy, 24 clinic attendees (16 neurologically unaffected patients and eight relatives) completed a short survey prior between February and July 2023.Results: Over a 9-year period, we recorded 15 deaths (17%), comprising 11 cases with neurodegeneration (groups A, B, D, F, and G) and 4 cases without neurodegeneration (groups A, C and V). Notably, there were no deaths attributable to skin cancer. Four deaths were linked to internal malignancies [median age: 52.5 years (IQR 41.8-58.75). The median survival age is 50 years (95% CI [34, Inf]) for those with neurological involvement, and 81 years (95% CI [81, Inf]) for those without. The latter is comparable to the general UK population (78.6 years for males, 82.6 years for females, 2020–2022) (2). The estimated probability of survival beyond age 40 is 0.68 (95% CI [0.47,0.98]) for individuals with neurological involvement and 0.90 (95% CI [0.73,1.00]) for those without.Only 11 of 24 survey respondents (46%) believed that life expectancy in neurologically unaffected XP patients was normal. One respondent (4%) estimated life expectancy at 20-29 years, 8 (31%) at 30-39 years, 1 (4%) at 50-59 years, and 3 reported uncertainty.Conclusion: We present evidence of improved survival outcomes in patients with XP in the UK, both with and without neurological involvement, compared to previously reported literature. While life expectancy for individuals with XP can be limited, particularly without appropriate care, advances in medical management and strict adherence to preventive measures have improved outcomes. It is important that outdated and potentially harmful misinformation online is updated and to convey to through discussions with patients and families that regular medical follow-ups, diligent photoprotection, and timely intervention for skin cancers, can enhance both longevity and quality of life for those affected by XP.REFERENCES:Bradford PT, Goldstein AM, Tamura D, Khan SG, Ueda T, Boyle J, Oh KS, Imoto K, Inui H, Moriwaki S, Emmert S, Pike KM, Raziuddin A, Plona TM, DiGiovanna JJ, Tucker MA, Kraemer KH. Cancer and neurologic degeneration in xeroderma pigmentosum: long term follow-up characterises the role of DNA repair. J Med Genet. 2011 Mar;48(3):168-76. doi: 10.1136/jmg.2010.083022. Epub 2010 Nov 19. PMID: 21097776; PMCID: PMC3235003.Office for National Statistics (ONS), released 11 January 2024, ONS website, statistical bulletin, National life tables – life expectancy in the UK: 2020 to 2022Alexandra Paolino1, Sally Turner1, Tanya Henshaw1, Joanne Palfrey1, Karla Balgos1, Paola Giunti, Ana M. S. Morley1, Shehla Mohammed1, Adesoji Abiona1, Alan R. Lehmann2, Hiva Fassihi11National Xeroderma Pigmentosum Service, Department of Photodermatology, St John's Institute of Dermatology, Guy's and St Thomas’ Foundation Trust, London SE1 7EH, United Kingdom;2Genome Damage and Stability Centre, University of Sussex, Falmer, Brighton BN1 9RQ, United Kingdom.Introduction: There is marked heterogeneity in the presenting clinical features of Xeroderma Pigmentosum (XP), both between and within complementation groups. Effective management relies on early diagnosis, stringent photoprotection to mitigate skin cancer-related morbidity and mortality, and regular dermatological and ophthalmological examinations to detect and treat malignancies promptly. Despite these measures, delays in diagnosis remain a challenge, emphasizing the need for increased awareness among healthcare providers.Aim: To evaluate presenting clinical features of XP and time from first symptom onset to diagnosis.Methods: A retrospective review was conducted on 133 XP patients (67 females, 66 males; age range 0–87 years) receiving specialist multidisciplinary care at a national centre. Of these, 100 patients were included in the study, excluding 29 diagnosed through older siblings and 4 with incomplete histories. Data collected included complementation group, presenting clinical features categorised into dermatological, ophthalmological, or neurological signs, age of symptom onset, age at diagnosis, and referring specialty.Results: The complementation groups represented included XP-A (n = 20), XP-B (n = 2), XP-C (n = 29), XP-D (n = 14), XP-E (n = 6), XP-F (n = 6), XP-G (n = 7), XP-V (n = 16). By age 3, 84% of patients had developed clinical signs of the condition (excluding those presenting with skin cancers), yet the mean age at diagnosis was 12.2 years (median 6; range 0.5–64 years).Initial clinical signs varied significantly. Exposed-site pigmentary changes appeared at a mean age of 5 years (range 0.5–44 years) and were predominantly observed in XP-C (83%, mean age 2.3 years, range 0.75–6 years) and XP-V (56%, mean age 14.4, range 2–44) patients.Photosensitivity, characterised by severe prolonged sunburn, was the primary symptom in XP-D (100%), XP-F (100%), XP-G (86%), and XP-A (55%) patients, excluding those with the milder XP-A variant. Median diagnostic delays were shorter in these complementation groups (range 3.2-11 years).Skin cancers at presentation were most common in XP-E (66%, mean age 26 years, range 15–40), XP-V (44%, mean age 35 years, range 16–46) and XP-C (7%, mean age 16 years, range 4–28 years).Ocular signs, including conjunctivitis and photophobia were the first presenting features in two XP-C patients aged 0.5 and 1 year. Neurological symptoms were the initial presenting feature in two XP-A patients who exhibited developmental delays by age two.Diagnostic delays were particularly pronounced in XP-E and XP-V patients, with median delays of 28.5 and 21.5 years, respectively. Dermatologists were the most frequent referrers, accounting for 73% of referrals, followed by geneticists (7%), general practitioners (10%), paediatricians (5%), neurologists (3%) and ophthalmologists (2%).Conclusion: Most XP patients exhibit clinical signs early in life, but significant diagnostic delays exist, particularly in groups with milder cutaneous manifestations where severe sunburn reactions or pigmentary changes are lacking. Dermatologists are the primary referrers, underscoring their critical role in early recognition. Increased awareness across all specialties is essential to improve diagnostic timelines and outcomes for XP patients.Guzzon Diletta1*, Paccosi Elena1*, Filippi Silvia1, Valeri Emma1, De Lanerolle Primal2 and Proietti-De-Santis Luca1#1Unit of Molecular Genetics of Aging, Department of Ecology and Biology (DEB), University of Tuscia, 01100 Viterbo, Italy.2Department of Physiology and Biophysics, College of Medicine, University of Illinois at Chicago, 835 S. Wolcott, Chicago, IL 60612.Cockayne Syndrome group A (CSA) is an ubiquitin E3 ligase belonging to the family of WD-40 repeat proteins. CSA was initially characterized, together with Cockayne syndrome group B (CSB) protein, as playing a role in Transcription Coupled Repair even if, in the last years, a growing body of evidence shows how this protein, together with CSB, exerts a key role in the regulation by ubiquitination and proteasomal degradation of a plethora of different proteins involved in the most disparate cellular processes. Mutations in CSA, as well as in CSB, result in Cockayne syndrome (CS), a human autosomal recessive disorder characterized by a variety of clinical features, including growth deficiency and severe neurological and developmental manifestations.Actin, a major component of the cytoplasm, has been recently described as abundant in its filamentous form (F-Actin) also in the nucleus, where it is involved in a variety of nuclear processes including transcription and chromatin remodeling. The nuclear export of Actin is mediated by Chromosomal Maintenance 1 or Exportin 1 (CRM1). Here, we demonstrate that CSA may regulate the nuclear localization of Actin by ubiquitinating its nuclear exporter CRM1, in such a manner to avoid the passage of CRM1/Actin complexes through the nuclear pore complex. We also demonstrate that CS-A patients derived fibroblasts display a hampered Actin nuclear retention, in favour of its nuclear export, as a consequence of a defective CRM1 ubiquitination. This unbalance in Actin localization results in both an altered and stiff cytoskeletal shape and in a drastic reduction of nuclear Actin foci. Furthermore, while normal cells display a preferential localization of CRM1 on the nuclear membrane, CS-A mutant cells show, instead, an aberrant presence of CRM1 as cytoplasmic foci, further confirming an abnormal rate of CRM1-mediated export. How to reconcile this defective export of nuclear Actin with Cockayne syndrome features? It is well known that nuclear Actin localizes at the promoters of certain genes, where it helps the recruitment or RNA polymerase II (RNA polII). Interestingly, in CS-A mutated patient's derived fibroblasts, we found a hampered recruitment of Actin on promoters of some genes, such as BDNF and BRD7 ones, corresponding to a defective recruitment of RNA polII on the same promoters and to a defective transcription of these genes. These results may potentially justify the transcriptional defects shown by CS-A patients, especially regarding the neurodevelopmental manifestations.It is still to determine if also CSB is someway involved in this new regulatory pathway, maybe being responsible of the degradation of the nuclear exporter protein CRM1. Further studies will be required to better define both the eventual role of CSB and the consequences of the impairment of Actin shuttling on the clinical features of CS patients.Silvia Filippi, Emma Valeri, Elena Paccosi, Diletta Guzzon and Luca Proietti De SantisUnit of Molecular Genetics of Aging, Department of Ecology and Biology (DEB), University of Tuscia, 01100 Viterbo, Italy.Cockayne syndrome (CS), defined as Nucleotide excision repair (NER) syndrome, is a rare autosomal recessive disorder linked to mutations in ERCC8 and ERCC6 genes, which encode for CS group A (CSA) and group B (CSB) proteins respectively, both of which play a role in Transcription Couples repair (TCR), a sub-pathway of NER, devoted to removal of lesions on transcribed genes. Although CS patients exhibit hypersensitivity to UV irradiation, they do not experience an increased risk of skin cancer occurrence in contrast to another NER syndrome defined as Xeroderma pigmentosum. While a loss-of-function mutation in the ERCC8 and ERCC6 genes causes a variety of senescence- and cell death-related abnormalities, increased expression of CSA and CSB proteins has been reported in cancer cells from different tissues often associated with increased proliferation and cell robustness. Recently, we demonstrated that CSA protein is over-expressed in breast cancer cells and its down-regulation by ASO technology dramatically reduces not only the tumorigenicity but also enhances the sensitization of BC cells to both oxaliplatin and paclitaxel drugs, two of the major chemotherapy agents used for triple-negative breast subtype. In this line, we decided to analyze the CSA expression in primary (WM115) and metastatic (WM266-4) melanoma cells. Melanoma is the most aggressive form of skin cancer. Research has made a great stride, in the last years, trough the introduction of innovative and effective therapies: immunotherapy and target therapy, unfortunately, some types of melanomas are refractory to therapeutic treatments. In this case, conventional chemotherapy with methylating agents: Dacarbazine (DTIC) and Temozolomide (TMZ) is considered as a last-line option. Both DTIC and TMZ are associated with unclear survival benefits and treatment-related toxicities. Our studies demonstrated that both WM115 and WM266-4 cells display an overexpression of CSA. Furthermore, CSA suppression greatly sensitizes both cell lines, in particular the metastatic ones, to both Dacarbazine (DTIC) and Temozolomide (TMZ) drugs, even at very low doses which are not harmful to normal cells, in term of cell proliferation, cell survival and apoptotic response. Further, studies are mandatory to evaluate whether CSA may be considered a very attractive target for the development of more effective antimelanoma therapies.Julie SoutourinaInstitute for Integrative Biology of the Cell (I2BC), CEA - CNRS - University Paris-Saclay, 91191 Gif-sur-Yvette FranceTranscription and DNA repair are fundamental functions of the cell. Their dysfunctions lead to cell death, mutagenesis and pathologies. In NER, transcription-coupled repair removes DNA lesions interfering with RNA polymerase II progression. Inherited NER defects lead to xeroderma pigmentosum, Cockayne syndrome and triochothiodystrophy with complex syndromes including sunlight sensitivity, skin cancer or premature aging and neurological symptoms. Mediator is an essential and conserved multisubunit coactivator complex. In human, neurodevelopmental diseases mapped to Mediator mutations were regrouped as Mediatorpathies. New Mediator variants were recently uncovered in patients with transcription and TCR defects. However, many questions remain unanswered on mechanisms of complex diseases related to transcription and NER deficiencies.The yeast Saccharomyces cerevisiae offers a unique opportunity to unveil the fundamental eukaryotic mechanisms thanks to its powerful genetic and genomic tools. Our work contributed to understanding of Mediator transcription function. Moreover, we have discovered its novel role by connecting transcription and NER via Rad2, the yeast homolog of human XP/CS-related XPG. Taking advantage of yeast, we transposed pathological Mediator mutations associated with CS-like symptoms and showed that they led to growth and UV-sensitivity phenotypes, and genetic interactions with TCR components. We are characterising their impact on physical interactions with Pol II and Rad2, transcription and DNA repair.Transcription also affects mutagenesis and DNA repair prevents mutations responsible for aging and diseases. However, mechanisms involved in mutagenesis associated with transcription and DNA repair remain to be fully understood. Recently, we developed an innovative microfluidic-based system, coupled with high-throughput sequencing, for mutation accumulation in yeast. We transposed XP, CS or TTD-associated mutations and are analysing their impact on mutagenesis using our microfluidic-based and reporter-gene approaches combined with mutagen treatments.In conclusion, we propose how the yeast model can give important insights into our understanding of the molecular mechanisms at the origin of complex human diseases related to transcription and NER deficiencies.Philipp-Kjell Ficht1, Anna Staffeld1, Wilhelm Sponholz1, Rüdiger Panzer1, Anneke Lemken1, Nataliya DiDonato2, Joseph Porrmann2, Mensuda Hasanhodzic3, Ales Maver4, Tasja Scholz5, Maja Hempel5, Oleksandra Kuzmich6, Steffen Emmert1, Lars Boeckmann11Clinic and Policlinic for Dermatology and Venereology, University Medical Center Rostock, Germany2Institute for Clinical Genetics, University Hospital Carl Gustav Carus at the Technische Universität Dresden, Germany3Department of endocrinology, metabolic diseases and genetics University Clinical Centre Tuzla, Bosnia and Herzegovina4Centre for Mendelian Genomics, Clinical Institute of Medical Genetics, UMC Ljubljana, Slovenia5Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany6DWI - Leibniz Institute for Interactive Materials e. V., Aachen, GermanyXeroderma pimentosum (XP) is an autosomal recessive disorder characterized by increased photosensitivity, actinic skin damage, neurological abnormalities, and an elevated risk of skin and mucosal cancers. This condition is caused by defects in genes encoding for components of the nucleotide excision repair (NER) pathway. In this study, genetic and functional analyses were performed on patients with a suspected clinical diagnosis of XP or those identified with mutations in an XP-related gene. For patients with an unknown genetic cause, DNA sequencing was conducted to determine the underlying genetic defect. Additionally, functional analyses of patient cells were performed to assess their repair capacity and survival rates following UV-C irradiation. Exome or Sanger sequencing revealed identical compound heterozygote mutations in ERCC2 (XPD) in two patients, one patient with a homozygous missense variant in DDB2 (XPE), one with a homozygous single nucleotide variant in XPA and one with a homozygous mutation in XPC. Sequencing of DNA from two further patients is currently conducted. The presents of a heterozygous variant in one of the parents was confirmed for the patients with a homozygous variant in XPA or XPC. The exposure of patient derived fibroblasts to UV-C irradiation showed no reduced post-UV-survival compared to wild type cells for cells from patients with genetic alteration in ERCC2 or DDB2, a slightly reduced post-UV-survival for XPC and no reduced post-UV-survival for cells with alterations in XPA. Preliminary results of a host cell reactivation assay (HCR) showed that the reduced DNA repair capacity of cells with a defect in DDB2 could be compensated by the transfection of the cells with wild type DDB2. No compensation was observed for cells with alterations in ERCC2. Hair analyses for patients with compound heterozygous mutations in ERCC2 showed neither a reduced cysteine content nor the typical tiger-tail pattern as seen in a patient with trichothiodystrophy (TTD) under polarized light microscopy. Overall this ongoing study characterizes and correlates the genotypes and phenotypes of seven patients with varied clinical symptoms.Lars Boeckmann1, Philipp Ficht1, Anna Staffeld1, Rüdiger Panzer1, Steffen Emmert11Clinic and Policlinic for Dermatology and Venereology, University Medical Center Rostock, GermanyThe nucleotide excision repair (NER) is essential for the repair of ultraviolet (UV)-induced DNA damage, such as cyclobutane pyrimidine dimers (CPDs) and 6,4-pyrimidine-pyrimidone dimers (6,4-PPs). Alterations in genes of the NER can lead to NER-defective syndromes. The main NER-defective syndromes comprise xeroderma pigmentosum (XP), Cockayne syndrome (CS), and trichothiodystrophy (TTD).Clinical and molecular-genetic assessment of XP-C patients from Germany revealed absence of sun-sensitive as well as neurological symptoms. The mean age of XP diagnosis was 9.4 years, and the median age of the first skin cancer was 7 years. We identified five new mutations including an amino acid deletion (c.2538_2540delATC; p.Ile812del) resulting in repair deficiency but no XPC message decay.Assessment of XPG-defective patients revealed that the type and location of mutations determine the clinical phenotype. We identified 3 missense mutations and showed by molecular means that these missense mutations in the I-region of the XPG protein impaired both repair and transcription and delayed the recruitment of other XP proteins to UV photodamage as well as their redistribution thereafter. The patients exhibited a XP/CS complex phenotype.We also identified two XPG and XPF splice variants with residual repair capabilities in NER. Almost all variants are severely C-terminally truncated and lack important protein-protein interaction domains. Interestingly, XPF-202, differing to XPF-003 in the first 12 amino acids only, had no repair capability at all, suggesting an important role of this region during DNA repair.German XPD-deficient patients exhibited a XP phenotype in accordance with established XP-causing mutations (c.2079G>A, p.R683Q; c.2078G>T, p.R683W; c.1833G>T, p.R601L; c.1878G>C, p.R616P; c.1878G>A, p.R616Q). One TTD patient was homozygous for the known TTD-causing mutation p.R722W (c.2195C>T). Two patients were compound heterozygous for a TTD-causing mutation (c.366G>A, p.R112H) and p.D681H (c.2072G>C) amino acid exchange, but exhibited different TTD and XP/CS complex phenotypes. Interestingly, the XP/CS patient's cells exhibited a reduced but well detectable mutated XPD protein expression compared with hardly detectable XPD expression of the TTD patient's cells.Further genotype-phenotype studies could be performed within the European Reference Networks for Rare Diseases (ERN-Skin).Francesca Brevi1, Arjan Theil2, Alan Lehmann3, Sebastian Iben4, Donata Orioli1 and Elena Botta11Istituto di Genetica Molecolare (IGM) CNR, Pavia, Italy2Department of Molecular Genetics, Erasmus MC, University Erasmus Medical Center, Rotterdam, The Netherlands3Genome Damage and Stability Centre, University of Sussex, Falmer, Brighton, UK4Department of Dermatology and Allergic Diseases, Ulm University, Ulm, GermanyTrichothiodystrophy (TTD) is a multi-system disease characterized by skin, neurological and growth abnormalities. The presence of photosensitivity defines the two main forms of TTD – the photosensitive (PS) and non-photosensitive (NPS) forms. Mutations in a variety of genes have been associated to the disease. They include three PS-TTD related genes that encode distinct subunits of the transcription/DNA repair factor TFIIH and seven NPS-TTD related genes encoding the beta subunit of transcription factor IIE -TFIIEβ, the splicing factors TTDN1 and RNF113A and four aminoacyl-tRNA synthetases which operate in translation. All these TTD-related factors participate in gene expression, thus raising the notion of TTD as a gene expression syndrome. It has been demonstrated that TTD-causing mutations in TFIIH subunits or TFIIEβ as well as knockout/knockdown of TTDN1 and RNF113A impact on transcription by RNA polymerase I. Consequently, ribosomal biogenesis is affected with concomitant error-prone translation and loss of protein homeostasis (proteostasis). Now, by taking advantage of our recently identified TTD cases mutated in methionyl-, threonyl- or alanyl-tRNA synthetase, we have investigated the quality of translation in tRNA synthetase-defective TTD cases. By using a luciferase-based assay, we found a high translation error rate in all tested TTD cells, indicating translation infidelity. In addition, survival assays in the presence of elevated concentrations of single specific amino acids suggested impaired accuracy of tRNA charging. These alterations are accompanied by accumulation of misfolded proteins, indicating a loss of proteostasis. Overall, translation infidelity and loss of proteostasis appear as a common underlying pathomechanism for the different forms of TTD, which may contribute to impaired development and neurodegeneration in patients.Jordana McLoone1,2, Kyra Webb2, Kathy Tucker3, Antoinette Anazodo2, Denise Wilson5, Linda Martin1,4,51UNSW Sydney, School of Clinical Medicine2Kids Cancer Centre, Sydney Children's Hospital3Hereditary Cancer Centre, Sydney Children's Hospital, UNSW4Dept Dermatology, Sydney Children's Hospital5Melanoma Institute AustraliaBackground: In Australia there are no dedicated diagnostic or management services for patients with xeroderma pigmentosum (XP).Aim: To understand the supportive care needs of families who have a child diagnosed with XP.Methods: Australian parents and carers of a child with XP, as well as children with XP 5–18 years with no intellectual disability were invited to participate. Participants were identified via clinical networks and social media patients support groups. A semi-structured interview was conducted in-person or via Zoom and focused on the diagnostic journey, current care, preferred models of care, psychosocial impact, and information needs. Interview data were transcribed verbatim and coded line-by-line using QSR NVivo Pro. Inductive thematic analysis was used to organize nodes and themes.Results: Eight adult carers and 3 children with XP where interviewed, including one family with XP-A, one family with XP-C, and two families with XP-D. Five out of the seven families identified participated.Most families had long delays before the diagnosis with misinterpretation of presenting symptoms. Wait times for genetic testing were 6–12 months. All families reported highly unmet informational needs, including how to sun protect, prognosis and management. Parents reported unmet psychological needs, including guilt, fear, grief, isolation and hypervigilance. Adaptions and sun protective requirements were costly.The preferred model of care for patients was a multidisciplinary team that included dermatology, ophthalmology, neurology, and allied health. Continuity of care was emphasized.Conclusion: The development of comprehensive clinical services to address the diagnostic, preventative, surveillance, treatment and supportive care needs of Australian XP patients is urgent.Riccardo Paolini1, Yvette Walker2, T. Xiong1, Konstantina Vasilakopoulou,1 Linda Martin3,41UNSW School of Built Environment, Faculty of Art, Design & Architecture.2UNSW Rare Diseases3UNSW School of Clinical Medicine, Faculty of Medicine & Health.4Sydney Children's Hospital5Melanoma Institute Australia.Background: Complete protection against all ultraviolent (UV) radiation requires individuals with xeroderma pigmentosum (XP) to wear highly protective garments, including a hood with a visor, full clothing, and gloves. Commercially available garments have been designed and tested for UV protection only, but may lead to substantial solar heat gains, resulting in human thermal discomfort, de facto restricting outdoor activity and impacting quality of life.Objective: To test the effect on thermal properties with of the addition of solar control film to the XP visor (PS90 by 3M).Methods: Surface temperature was measured with a thermal camera (T540 by FLIR). The optical properties of materials were characterised with a UV-Vis-NIR spectrophotometer with a 150 mm integrating sphere (Lambda 1050+ by Perkin Elmer), and the broadband properties (solar, uv, vis, and nir) were computed with the solar irradiance distribution of global horizontal radiation with air mass 1, following ASTM E903.Results: The UV transmittance of the plain visor is zero in the 250-380 nm wavelength range, but there is some light transmission in the 380-400 nm range (from 0.02 at 385 nm to 0.64 at 400 nm), resulting in a total UV transmittance of 0.08, and solar transmittance of 0.83.With solar control film (PS90), the total UV transmittance reduced to 0.02, and solar transmittance decreased to 0.59. The PS90 film added to the visor reduces visible transmittance by 0.11, without compromising a clear vision, and reduces near-infrared transmission by 0.45, therefore almost halving the solar heat gains in the non-visible portion of the solar spectrum. Further, the clear film displays low solar absorbance and, therefore, limits surface overheating. When these combinations were tested outdoors (clear sky conditions 28.4°C, solar radiation of 365 W/m2 and UV radiation of 13 W/m2), the addition of PS90 film on top of the was 2.9 °C cooler than the plane visor 0.6 m/s, solar radiation of 365 W/m2 and UV radiation of 13 W/m2.Conclusion: XP patients do not have easy access to protective garments with are both UV safe and thermally safe, particularly in warm climates. Addition of a readily available solar film to the UV visor halved solar heat gains.Vuong-Brender Thanh1,2 and Schumacher Björn1,21Institute for Genome Stability in Aging and Disease, Medical Faculty, University and University Hospital of Cologne, Cologne, Germany.2Excellence Cluster for Cellular Stress Responses in Aging-Associated Diseases (CECAD), Center for Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany.Thanks to a simple body architecture, the nematode C. elegans can be used to study DNA damage response both at cellular and organismal levels. We used C. elegans xpc-1 mutants, ortholog of the mammalian sensor of DNA damage XPC, to understand alternative repair in mutants defective for the Global Genome Nucleotide Excision Repair (GG-NER) pathway. XPC-1 is strongly expressed in the germline of C. elegans. When first instant larvae of xpc-1 mutants are UV treated, the primordial germ cells (PGCs) fail to develop a germline during the subsequent larval growth to adulthood. We discovered that mutations in the endonuclease gen-1, ortholog of mammalian resolvase of Holiday junctions GEN1, strongly enhanced the UV-induced germline developmental defects of xpc-1 mutants. This increase in UV-sensitivity requires the catalytic activity of GEN-1 as well as its C-terminal region. Our data shows that GEN-1 meditates germ cell arrest in xpc-1 mutants in response to UV, suggesting GEN-1 regulates DNA damage checkpoint in PGCs when the lesions are not repair by the canonical GG-NER pathway. The arrest seems to allow an alternative repair pathway independent of the double strand break repair mediated by brc-1/BRCA1 and brd-1/BARD1, and the Fanconi Anaemia pathway mediated by fcd-2/FANCD2. The absence of GEN-1 – dependent alternative repair results in replication and chromosomal segregation defects during subsequent S-phase and mitosis respectively, that can be rescued partially by activating the spindle assembly checkpoint. Our results point to a potentially important regulator of DNA repair in XP patients.Teodora Svilenska1, Chiara Cimmaruta2, Claudia Bogner3, Vincent Laugel4, Wolfram Gronwald3, Miria Ricchetti2, York Kamenisch1* and Mark Berneburg1*1Department of Dermatology, University Hospital Regensburg, 93042 Regensburg, Germany, Tel.: 0941 944-9601,2U5 Molecular Mechanisms of Pathological and Physiological Ageing, Institut Pasteur, 25, rue du Dr. Roux, 75724 Paris Cedex 15, France3Institute of Functional Genomics, Department Functional Genomics, Am BioPark 9, 93053 Regensburg, Germany, Tel.: 0941 943 50154University Hospital of Strasbourg, Neuromuscular Centre at Hautepierre Hospital, Hautepierre Hospital, Avenue Molière, 67000 Strasbourg, France*: corresponding authorsemail: [email protected], [email protected]Cockayne syndrome (CS), a rare genetic disease with progeroid symptoms, like, progressive severe neurological defects and UV sensitivity, has no treatment up to now. The investigation of metabolic changes, which are associated with aging processes or stressors, is necessary to increase the knowledge of the complex processes leading to aging of cells and organisms.It was shown in previous work, that exposure of human skin cells to stressors like UVA irradiation or reactive oxygen species (ROS) leads to significant changes in the cell metabolism, especially in the glucose metabolism. The high levels of UVA induced consumption of glucose and pyruvate could be involved in the ROS detoxification strategies of these UVA exposed cells. In addition to this it is known that CS cells can exhibit higher levels of cellular ROS damage than WT cells.In this project, we investigated the impact of stressors (ROS) on the metabolism and oxygen consumption in primary human skin fibroblasts derived from CS patients with the premature aging syndrome or from healthy individuals (WT). These cells were treated with repetitive low dose UVA irradiation (inducing ROS) with subsequent measurement of cellular oxygen consumption using a Clark type electrode and metabolic changes in the supernatant of the cells, using nuclear magnetic resonance spectroscopy (NMR).UVA irradiation induced significant changes in many metabolites (glucose, lactate, pyruvate, acetate, glutamine, glutamate, choline, alanine, betaine) in the cellular supernatant. Similar to WT cells, CS cells showed higher glucose and pyruvate consumption, as well as higher lactate and alanine secretion upon UVA treatment. Interestingly, metabolic differences between WT and CS cells are already present without external stressors (UVA irradiation) and many of these differences increase upon UVA treatment. Concerning cellular respiration, differences in the oxygen consumption rate, between CS and WT cells were visible without external stressors. WT cells show a higher oxygen consumption rate than CS cells. The application of stressors (UVA irradiation) enhanced these differences between WT cells and CS cells.This study revealed differences in metabolism and respiration between CS cells of patients with premature aging symptoms and WT cells. It is known, that, under specific conditions, processes of cellular respiration can generate high levels of ROS. Therefore, it can be speculated, that CS cells try to exploit metabolic ROS detoxification strategies associated to glycolysis (higher glucose and pyruvate consumption than WT cells) in order to reduce ROS production during respiration (lower respiration rate than WT cells).Introduction: Cutaneous malignancies are the leading cause of premature mortality among patients with Xeroderma Pigmentosum. Cutaneous Squamous Cell Carcinoma (cSCC) is the most prevalent skin cancer seen among XP patients in our setting. Rapid local and distant metastases due to their impaired DNA function make it difficult to treat with surgery. Cemiplimab has been approved for treating locally advanced and metastatic cSCC. It is however not available in developing countries like Tanzania.Case Presentation: A 9 year old male presented to us in January 2023 with two large ulcerated tumours on the scalp (temporal region), a fungating mass on the left mandibular region. Prior to attending our facility he had multiple excisions done at peripheral hospitals but the tumours always recurred. He had also received 4 cycles of chemotherapy at the national hospital. Multidisciplinary team effort with ENT and general surgeons was crucial from the beginning of treatment. Biopsies from the national hospital revealed SCC on both scalp tumours invading bone, CT scan of the mandibular tumour revealed SCC with invasion of the parotid gland, pushing the left external auditory meatus and causing severe pain. Paracetamol and ibuprofen did not relief the pain and we requested to start him on morphine. He had anaemia of 7g/dl since the parotid mass bled profusely during wound dressing and was transfused with 3 units of blood. ENT and general surgeons did debulking surgery; underlying muscles were infiltrated with the mass hence complete excision was not possible. A week later the scalp tumours were excised and he was planned for palliative care on discharge. In September 2023 he came for follow up with recurrent tumours on the same sites and even bigger than previously. After several discussions in the tumour board and after asking for donations, we were able to acquire the monoclonal antibody Cemiplimab. He was started on cycles of Cemiplimab to be given after every 2 weeks and he has received 21 cycles. Significant shrinkage of the tumour was noted from cycle 15 where he only had shallow ulcerations on the scalp. There is no new or recurrent cancer growth seen and all the wounds have closed up.Conclusion: This case is an example of the hurdles, unsuccessful as they may be, that had to be undertaken to treat advanced cSCC in XP due to lack of availability of novel treatments like Cemiplimab which through research has proven to be successful in treating aggressive cSCC. XP patients are perfect candidates for treatment with immunotherapy and this should be available in all settings.Andrey A. YurchenkoINSERM U981, Gustave Roussy Cancer Campus, Université Paris Saclay, Villejuif, France[email protected]Fatemeh RajabiINSERM U981, Gustave Roussy Cancer Campus, Université Paris Saclay, Villejuif, France[email protected]Tirzah B. P. LajusDepartamento de Biologia Celular e Genética, Universidade Federal do Rio Grande do Norte, Av. Senador Salgado Filho, s/n, Natal, 59078–970, Brazil[email protected]Hiva FassihiNational Xeroderma Pigmentosum Service, Department of Photodermatology, St John's Institute of Dermatology, Guy's and St Thomas’ Foundation Trust, London SE1 7EH, United Kingdom[email protected]Chikako NishigoriDivision of Dermatology, Department of Internal Related, Kobe University Graduate School of Medicine, Kobe, Japan[email protected]Carlos F. M. MenckDepartment of Microbiology, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, SP, Brazil[email protected]Alain SarasinCNRS UMR9019 Genome Integrity and Cancers, Institut Gustave Roussy, Villejuif, France[email protected]Sergey NikolaevINSERM U981, Gustave Roussy Cancer Campus, Université Paris Saclay, Villejuif, France[email protected]Xeroderma Pigmentosum (XP) is characterized by a 1000-fold increased risk of skin cancer due to deficiencies in the NER or TLS pathways. The genomic mechanisms of somatic mutagenesis responsible for this increase are not yet fully understood.We sequenced genomes from a unique collection of skin tumors (n = 38) originating from cancer-prone XP subgroups (XP-A/C/D/E/V) and developed in vitro models (XP-C/V) to elucidate the mechanisms of UV-induced mutagenesis in XP using detailed bioinformatic analyses.The ultra-mutated tumor phenotype was observed in skin tumors with impaired GG-NER (XP-E = 350 mut/MB, XP-C = 162 mut/MB) and translesion synthesis (XP-V = 248 mut/MB). Mutational profiles of XP skin tumors with NER defects were dominated by C>T mutations, with each group exhibiting specific trinucleotide context features. XP-C and XP-D tumors showed a notably large percentage of CC>TT double-base substitutions (17–20%) compared to sporadic skin cancers (4.7%). Mutations in XP-A and XP-D tumors, with impaired GG-NER and TC-NER, exhibited a uniform distribution along chromatin genomic compartments, implying that NER activity is a major modulator of genome-wide mutation rate heterogeneity.XP-V skin tumors with dysfunctional TLS polymerase eta were characterized by a specific mutational profile, including an excess of TG>TT substitutions (28%) absent in sporadic skin cancers. These mutations likely result from error-prone bypass of rare, atypical photolesions in TpA and TpG contexts in the absence of polymerase eta. The mutational signature of canonical UV-induced C>T mutations in pyrimidine dimers was distinct in XP-V tumors, primarily defined by incorrect nucleotide insertion at the 3’ end of photodimers (40-fold higher compared to sporadic cancers). This pattern likely reflects error-prone insertion and error-free extension steps performed by different TLS polymerases.WGS analysis of clones from UV-irradiated XPC-KO and POLH-KO cell lines revealed 3-fold and 11-fold increased mutagenesis rates, respectively, compared to wild-type cells. These findings demonstrate that error-free TLS bypass plays a major, if not greater, role in reducing UV-induced mutations alongside NER. Genomic analysis of cell lines transfected with photolesion-specific photolyases highlighted the primary role of CPD in mutation generation and 6-4PP in the DNA damage response.The accumulation of unrepaired DNA lesions on the untranscribed strand, nonspecific TLS activity, and the inability to bypass atypical photolesions error-free collectively explain the increased incidence of skin cancer in XP patients.Genetic analyses of large cohorts of cancer patients have revealed a correlation between somatic mutations in DNA repair pathway genes and the responsiveness of patients to DNA-damaging chemotherapeutics and immune checkpoint inhibition. In line with this, several case studies have shown that Xeroderma Pigmentosum (XP) patients with melanoma respond well to anti-PD1 therapy, suggesting that XP melanomas enable an immune-favoured tumor environment. To examine nucleotide excision repair (NER) deficient melanomas in vivo, we focused on the helicase ERCC2/XPD and developed a melanoma mouse model with ERCC2 wildtype (wt) or ERCC2-mutant tumors that harboured the deleterious point mutations K48R or D234N, the latter occurring in XP patients. For this purpose, we engineered murine melanoma cells that were first characterized in vitro and then transferred to C57BL/6J mice. As expected, XPD-mutant cells displayed increased sensitivity to UV irradiation and cisplatin treatment in cell culture. In vivo, XPD-K48R melanomas developed only in a minority of cases. XPD-D234N tumors developed earlier than XPD-wt tumors, consistent with the observed increased proliferation rate of XPD-D234N cells under basal conditions. Despite their rapid onset, 50% of XPD-D234N melanomas underwent spontaneous regression within 2–3 weeks, a phenomenon never observed in XPD-wt tumors. When mice bearing XPD-D234N melanomas were treated with a combination of cisplatin and PD-1 blocking antibody, almost all tumors regressed, while no therapy response was observed for mice with XPD-wt melanomas. These findings suggest that XPD-mutant melanomas are more easily resolved by the immune system of the host, particularly under conditions of NER-associated DNA damage and immune therapy. Future research will focus on the molecular mechanisms underlying this enhanced therapeutic responsiveness, paving the way for potential clinical applications targeting XPD in cancer.Tycho E.T. Mevissen1,2, Maximilian Kümmecke3, Ernst W. Schmid1, Lucas Farnung3, and Johannes C. Walter1,21Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA2Howard Hughes Medical Institute3Department of Cell Biology, Harvard Medical School, Boston, MAIn transcription-coupled DNA repair, RNA polymerase II stalling at DNA lesions leads to the efficient activation of nucleotide excision repair (TC-NER). This pathway was discovered almost 40 years ago, yet fundamental questions about its mechanism remain unanswered, in large part due to the lack of a cell-free system that supports this pathway. We have recapitulated vertebrate cell-free TC-NER, and we use this system to study STK19, a candidate TC-NER factor known to promote transcription recovery after cellular exposure to UV light. When a plasmid containing a site-specific cisplatin DNA intrastrand crosslink is transcribed in frog egg extracts, error-free repair is observed that depends on the canonical repair proteins CSB, CRL4CSA, UVSSA, ELOF1, as well as STK19. Structural prediction and cryo-electron microscopy indicate that STK19 is an integral component of the TC-NER complex that interacts with CSA-DDB1, the RNA polymerase II subunit RPB1, and the XPD helicase subunit of TFIIH. Mutating these interfaces disrupts cell-free TC-NER, and molecular modeling suggests that STK19 positions TFIIH such that the damaged DNA strand is threaded into the XPD helicase for subsequent lesion verification. In conclusion, our novel cell-free system that supports bona fide eukaryotic TC-NER strongly suggests that STK19 couples RNA polymerase II stalling to TFIIH-dependent downstream nucleotide excision repair events.Sikandar G. Khan1, Wenelia Baghoomian1, Christiane Kuschal1, Deborah Tamura1, Maxwell P. Lee1, John J. DiGiovanna1, *, Rodrigo Cepeda-Valdes2, Julio Salas-Alanis3 and Kenneth H. Kraemer11Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, United States2Dystrophic Epidermolysis Bullosa Research Association Mexico Foundation, Monterrey, Mexico; 3Instituto Dermatologico de Jalisco, Jalisco, Mexico, *DeceasedTrichothiodystrophy (TTD) is a rare (1 per million) autosomal recessive multisystem developmental disorder characterized by short, brittle hair with transverse “tiger-tailed banding” on polarized microscopy. TTD has been reported to be caused by mutations several different functional groups of genes: nucleotide excision repair (NER)/ basal transcription factor II H (TFIIH) genes: ERCC2/XPD, ERCC3/XPB and GTF2H5/ TTDA; amino acid charging tRNA genes (TARS, MARS1, AARS1, and CARS); basal transcription factor II E (GTF2E2/TFIIEβ); X-linked ring finger protein 113A (RNF113A), and a gene of unknown function (MPLKIP/TTDN1). We performed whole exome sequencing to identify a candidate gene in Sabinas brittle hair syndrome, a mild form of TTD. We report 5 non-photosensitive adult patients from 3 unrelated families with a homozygous missense mutation in DBR1 (p.D262Y) encoding the RNA lariat debranching enzyme DBR1 which catalyzes the removal of introns from pre-mRNA in the nucleus. Post-UV DNA repair was normal, indicating that DBR1 was not involved in NER/TFIIH. The cells had reduced levels of DBR1 mRNA and no detectable DBR1 protein. Previous reports described interaction of DRB1 and TTDN1 proteins. We found markedly reduced levels of TTDN1 protein in cells from patients with DBR1 mutations and no detectable levels of TTDN1 protein in the cells from patients with TTDN1 mutations. The stabilization of either of these proteins is critical for splicing and transcription. Genetic analysis suggests an ancient origin of this mutation. Thus, we identified DBR1 as causing Sabinas brittle hair syndrome supporting the hypothesis that TTD can be caused by transcriptional impairment.Marc Majora, Rituparna Bhattacharjee, Selina Dangeleit, Andrea Rossi, Jean KrutmannIUF – Leibniz-Institut für umwelt- medizinische Forschung GmbH, Düsseldorf, GermayXeroderma pigmentosum type A (XPA), an inherited disease characterized by UV hypersensitivity, high skin cancer risk and premature aging, is thought to be caused by defective repair of nuclear DNA. Recent studies, however, suggest that XPA proteins might have functions beyond nuclear DNA repair. Here we show – by analyzing purified mitochondrial fractions from primary human dermal fibroblasts (HDF) – that XPA proteins are located inside the mitochondria. In particular, mitochondrial XPA content was increased when HDF were either irradiated with UVB or treated with the pro-oxidant menadione suggesting that XPA might be important for repairing damage inside the mitochondria and protecting their integrity. Accordingly, sequencing of mitochondrial DNA (mtDNA) of HDF obtained from XPA patients (XPA HDF) revealed an elevated load of mutations as compared with healthy HDF, which was further increased by UVB irradiation. These data suggest that XPA is not only involved in the repair of nuclear DNA but also participates in the repair of mtDNA. The pivotal role of XPA in maintaining mitochondrial function was also reflected by a RNA-Seq transcriptome analysis showing that “Mitochondrial Gene Expression” and “Mitochondrial Translation” were among the most severely suppressed biological processes in UVB-irradiated XPA HDF. To assess potential consequences for mitochondrial function, we next measured the cellular ATP production rate. We found that unirradiated XPA HDF had a higher total ATP production rate than healthy HDF, which was due to increased mitochondrial but not glycolytic ATP production rate. If cells were stressed by UVB irradiation, mitochondrial ATP production rate in XPA HDF was reduced by more than 50% while it remained stable in normal HDF. Thus, XPA HDF have an increased ATP demand, which in unstressed cells can still be met by their mitochondrial function. Upon irradiation, however, compensation fails and XPA HDF become energy deficient. As the chaperone HSP90 serves as an ATP sensor which stabilizes proteins in an ATP-dependent manner, we next analyzed the abundance of HSP90 client proteins. HSP90 levels remained constant, but a marked loss of ErbB2, EGFR, STAT3 and SIRT1 was detected in irradiated XPA HDF when compared to healthy HDF, reflecting collapse of proteostasis. Our results indicate that XPA proteins are present in mitochondria where they maintain integrity of mtDNA and mitochondrial function to ensure cellular ATP supply and thereby prevent collapse of proteostasis, a well-known driver of aging.Paola Giunti, Hector Garcia-Moreno, Douglas R Langbehn, Adesoji Abiona, Isabel Garrood, Zofia Fleszar, Marta Antonia Manes, Ana M Susana Morley, Emma Craythorne, Shehla Mohammed, Tanya Henshaw, Sally Turner, Harsha Naik, Istvan Bodi, Robert P E Sarkany, Hiva Fassihi, Alan R LehmannNational Xeroderma Pigmentosum Service, Department of Photodermatology, St John's Institute of Dermatology, Guy's and St Thomas' Foundation Trust, London SE1 7EH, United KingdomandGenome Damage and Stability Centre, University of Sussex, Falmer, Brighton BN1 9RQ, United KingdomXeroderma pigmentosum (XP) results from biallelic mutations in any of eight genes involved in DNA repair systems, thus defining eight different genotypes (XPA, XPB, XPC, XPD, XPE, XPF, XPG and XP variant or XPV). In addition to cutaneous and ophthalmological features, some patients present with XP neurological disease. It is unknown whether the different neurological signs and their progression differ among groups. Therefore, we aim to characterize the XP neurological disease and its evolution in the heterogeneous UK XP cohort.Patients with XP were followed in the UK National XP Service, from 2009 to 2021. Age of onset for different events was recorded. Cerebellar ataxia and additional neurological signs and symptoms were rated with the Scale for the Assessment and Rating of Ataxia (SARA), the Inventory of Non-Ataxia Signs (INAS) and the Activities of Daily Living questionnaire (ADL). Patients’ mutations received scores based on their predicted effects. Data from available ancillary tests were collected.Ninety-three XP patients were recruited. Thirty-six (38.7%) reported neurological symptoms, especially in the XPA, XPD and XPG groups, with early-onset and late-onset forms, and typically appearing after cutaneous and ophthalmological symptoms. XPA, XPD and XPG patients showed higher SARA scores compared to XPC, XPE and XPV. SARA total scores significantly increased over time in XPD (0.91 points/year, 95% confidence interval: 0.61, 1.21) and XPA (0.63 points/year, 95% confidence interval: 0.38, 0.89). Hyporeflexia, hypopallesthaesia, upper motor neuron signs, chorea, dystonia, oculomotor signs and cognitive impairment were frequent findings in XPA, XPD and XPG. Cerebellar and global brain atrophy, axonal sensory and sensorimotor neuropathies, and sensorineural hearing loss were common findings in patients. Some XPC, XPE and XPV cases presented with abnormalities on examination and/or ancillary tests, suggesting underlying neurological involvement. More severe mutations were associated with a faster progression in SARA total score in XPA (0.40 points/year per 1-unit increase in severity score) and XPD (0.60 points/year per 1-unit increase), and in ADL total score in XPA (0.35 points/year per 1-unit increase).Symptomatic and asymptomatic forms of neurological disease are frequent in XP patients, and neurological symptoms can be an important cause of disability. Typically, the neurological disease will be preceded by cutaneous and ophthalmological features, and these should be actively searched in patients with idiopathic late-onset neurological syndromes. Scales assessing cerebellar function, especially walking and speech, and disability can show progression in some of the groups. Mutation severity can be used as a prognostic biomarker for stratification purposes in clinical trials.Mark BerneburgDepartment of Dermatology, University Hospital Regensburg, GermanyThe human genome is constantly exposed to various sources of DNA damage. Ineffective protection from this damage leads to genetic instability, which can ultimately give rise to somatic disease, premature aging and cancer. Therefore, our organism commands a number of highly conserved and effective mechanisms responsible for DNA repair. If these repair mechanisms are defective due to germline mutations in relevant genes, rare diseases with DNA repair deficiencies can arise. Today, a limited number of rare hereditary diseases characterized by genetic defects of DNA repair mechanisms is known, comprising ataxia telangiectasia, Nijmegen breakage syndrome, Werner syndrome, Bloom Syndrome, Fanconi anemia, Cockayne syndrome Trichothiodystrophy as well as Xeroderma pigmentosum. Although heterogeneous in respect to selected symptoms, these rare disorders share many clinical features such as growth retardation, neurological disorders, premature aging, skin alterations including abnormal pigmentation, telangectasia, xerosis cutis, pathological wound healing as well as an increased risk of developing different types of cancer. Better understanding of underlying molecular pathology in these diseases, has given rise to potential treatment approaches. In this talk, the different routes and modes of action for therapeutic approaches – ranging from treatments of underlying mechanisms to treatments of the different segmental clinical symptoms of these patients – will be discussed.Nihan Erden1, Björn Schumacher11Institute for Genome Stability in Ageing and Disease, Cologne Excellence Cluster for Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of CologneDNA damage is a causal factor of both cancer development and the aging process. The tumor suppressor p53 is a central mediator of the DNA damage response (DDR) and the single most frequently mutated gene in human cancer. Many studies showed that cell-cycle and apoptosis functions of p53 are important for preventing tumor development and the activation of p53 was regulated cell-autonomously depending on the type and severity of the DNA damage. It was recently discovered that the p53-mediated DDR in stem cells is not regulated only cell-autonomously but also regulated through signalling via the niche cells. The translation initiation factor IFE-4 in C. elegans is activated in somatic gonad precursor niche cells that surround the primordial germ cells, when the latter carry DNA damage. Moreover, it was demonstrated that the IFE-4 ortholog eIF4E2 in mammals is induced in niche cells upon UV-induced DNA damage and is required for the induction of p53 in hair follicle stem cells (HFSCs). These data thus indicate a highly conserved mechanism of non-cell-autonomous regulation of the p53-mediated DDR in stem cells.We are currently employing in vivo and ex vivo experimental systems with eIF4E2 epidermis specific knockout mice to dissect the mechanisms of the interactions between niche and stem cells, and to understand the role of eIF4E2 in skin homeostasis and carcinogenesis. To further assess the clinical relevance of the eIF4E2 function, we will characterize eIF4E2 in human squamous cell carcinoma.Dr Hiva FassihiNational Xeroderma Pigmentosum Service, Department of Photodermatology, St John's Institute of Dermatology, Guy's and St Thomas’ Foundation Trust, London SE1 7EH, UKProf Alan LehmannGenome Damage and Stability Centre, University of Sussex, Falmer, Brighton BN1 9RQ, UKOver 100 patients with Xeroderma Pigmentosum (XP), over 30 with Cockayne Syndrome (CS), and 13 with Trichothiodystrophy (TTD) are under long-term follow-up in the UK National Nucleotide Excision Repair (NER) Multidisciplinary Service. Involvement of the UK patient support groups, Action for XP and Amy and Friends, is essential in the care of these patients.The aims of the specialist team of clinicians, nurses and scientists is to improve clinical outcomes and reduce morbidity and mortality. Over the last 14 years, life expectancy of patients with XP in the UK has significantly improved when compared to data on 106 patients from a National Institutes of Health study analysing the worldwide literature from 1971 to 2009. In the UK, XP patients without neurodegeneration now have a life expectancy comparable to the general UK population, because of early diagnosis, meticulous photoprotection and prompt diagnosis and treatment of any skin and ocular cancers.Functional studies and molecular analysis to determine the pathogenic variants in the NER genes (part of the specialist service) have enabled the detailed genotype-phenotype examination of these patients. The careful clinical assessment of suspected cases has led to the discovery of a new XP complementation group, XP-J, with mutations in the GTF2H4 gene, and contributed to the reporting of MORC2-related disorder with phenotypic similarities to CS.Among the patients visiting the multidisciplinary clinic, several groups have relatively mild phenotypes. In most of these cases, in XP-A, D and G, they are associated with mutations at splice donor sites (outside the invariant GT nucleotides), causing abnormal splicing of most of the mRNA, but a residual amount of normally spliced mRNA. The resulting small amount of normal protein is sufficient to ameliorate or delay the onset of the clinical features. In four CS patients, mutation of the G at the fifth base of a splice donor site results in a markedly delayed onset of the clinical features.Marvin van Toorn, Jurgen MarteijnDepartment of Molecular Genetics and Oncode Institute, Erasmus University Medical Centre, Rotterdam, the NetherlandsNucleotide excision repair (NER) preserves genome stability through a ‘cut-and-patch’-type DNA repair reaction. Whereas the initial NER reaction steps that sequentially recognize, verify and excise helix-distorting DNA lesions through dual incision are well-characterized, mechanistic insight how the generated ssDNA gap is subsequently restored remains limited. Here, we study the mechanisms and factors involved in this late, post-incision NER step. We show that RFC mediates PCNA recruitment and loading at NER-generated ssDNA gaps, after which POLD3 displaces RFC to recruit POLD1 and enable polδ-dependent repair synthesis. Subsequent LIG3-mediated nick ligation promotes PCNA unloading by ATAD5-RLC, which facilitates PCNA recycling to newly NER-generated ssDNA gaps. Interestingly, we found that PCNA and polδ recruitment to sites of DNA damage was severely reduced in actively replicating cells. This could explain the existence of a parallel, non-redundant and PCNA-independent gap restoration pathway involving the alternative clamp loader CTF18-RLC, polε and LIG1. Collectively, our study provides important insights into the intricate mechanisms that preserve genomic integrity by coordinating the productive restoration of NER-generated ssDNA gaps throughout the cell cycle.Chikako Nishigori1, Mariko Tsujimoto1 and Shinichi Moriwaki21Division of Dermatology, Department of Internal Related, Graduate School of Medicine, Kobe University, Kobe, Japan2 Department of Dermatology, Osaka Medical and Pharmaceutical UniversityXeroderma pigmentosum (XP) is an autosomal recessive DNA repair disorder characterized by photosensitivity and progressive central and peripheral nervous system impairment. Currently, there are no effective treatments for XP aside from avoiding UV exposure. It has been shown that XP cells are impaired in scavenging ROS and oxidative DNA damage. Therefore, several antioxidants were examined for reducing cytotoxicity caused by oxidative stress in XP-A cells. Since in vitro experiments showed N-acetyl-5-methoxytryptamine and nicotinamide reduced cytotoxicity of XP-A cells caused by radical inducers, we conducted an in vivo experiment to investigate the therapeutic potential of N-acetyl-5-methoxytryptamine. Treatment with N-acetyl-5-methoxytryptamine mitigated UV-induced inflammation, skin tumorigenesis and hearing deterioration in XP model mice. Our results show that N-acetyl-5-methoxy-tryptamine could alleviate XP symptoms through its anti-inflammatory and antioxidant properties. <https://www.sciencedirect.com/science/article/pii/S0923181125000039>.Therefore, we conducted a clinical trial on the efficacy of N-acetyl-5-methoxytryptamine (NPC-15) for patients with XP with exaggerated sunburn-reaction type by a multicenter, double-blinded placebo-controlled, two-group crossover study followed by a 52-weeks open study. Ethics approval was overseen by the Kobe University Institutional Review Board and Osaka Medical and Pharmaceutical University Institutional Review Board, and the study was conducted in accordance with the approved protocol (Japan Registry of Clinical Trials (jRCT) identifier: jRCTs051210181. Registered on February 23, 2022. The clinical trial was conducted from April 2022 to December 2023. Twenty patients (Age; 10.6±6.8, F/M; 12/8). Eighteen patients were XP-A. After key open, all data was analyzed and statistically investigated. In the primary endpoint, the MED, 72 hours (+/-6 hours) after UV irradiation on the 15th day (crossover period I and crossover period II) of investigational drug administration, the treatment effect in NPC-15 administration did not show a statistically significant improvement compared to placebo administration. From the viewpoint of individual patients, data suggesting a usefulness on some of the items including neurological severity scale score on XP were obtained. NPC-15 had no significant safety problem. Brief summary is available through the URL below. <https://jrct.niph.go.jp/latest-detail/jRCT2051210181>.Melanie van der Woude, Karen L. Thijssen, Mariangela Sabatella, Jurgen A. Marteijn, Wim Vermeulen, Hannes LansDepartment of Molecular Genetics, Erasmus MC, Rotterdam, NetherlandsThe versatile nucleotide excision repair (NER) pathway protects organisms against the harmful effects of various types of helix-distorting DNA damage. Hereditary NER deficiency gives rise to several human cancer-prone and/or progeroid disorders, including xeroderma pigmentosum, Cockayne syndrome, trichothiodystrophy, or a combination of these. It is not exactly understood how defects in the same DNA repair pathway cause different disease features and severity.To better understand the pathogenesis underlying different NER disorders, we make use of human cellular and C. elegans model systems to investigate mechanisms of DNA repair and their in vivo impact. We previously reported that the core NER machinery is continuously targeted to DNA damage in human cells carrying severe NER disease mutations. Here we show, using real-time imaging, that different types of NER deficiency differently affect the binding of core NER factors to DNA damage and that the prolonged binding of specific NER factors to DNA damage correlates to NER disease severity. Using C. elegans, we show that DNA damage can cause a strong developmental arrest and neuronal dysfunction, which is dependent on transcription-coupled DNA repair and on the persistence of specific DNA repair intermediates in the absence of repair. Together, these results identify stalled transcription-coupled NER intermediates as a pathogenic feature of NER deficiency and show that these adversely affect tissue functionality and organismal development.Vilhelm A BohrUniversity of Copenhagen, Center for Healthy Aging, and previously National Institute on Aging, NIHWe find that some DNA repair defective diseases with severe neurodegeneration have mitochondrial dysfunction. Our studies involve cell lines, the worm (c.elegans), and mouse models and include the premature aging syndromes Xeroderma pigmentosum group A, Cockaynes syndrome, Ataxia telangiectasia and Werner syndrome. It also includes models of Alzheimers Disease (AD). Under these conditions we find a pattern of hyperparylation, deficiency in NAD+ and Sirtuin signaling and mitochondrial stress, including deficient mitophagy as a prominent feature. NAD supplementation stimulates mitochondrial functions including mitophagy and stimulates DNA repair pathways. Cockayne syndrome (CS) mice have a hearing deficit that reflects the one seen in the patients. Short term NAD supplementation with NR deminishes the hearing loss. The hearing loss is a of a similar type seen in age related hearing loss. Treatment of mice with NR improves the age related hearing loss. Current studies in CS mice show kidney disease reflecting what is also seen in many CS patients and the mice have deficits in NAD synthesis pathways.Clinical trials with NAD intervention have shown benefits in AT patients and a current intervention study in Werner patients also shows some benefits. These will be discussed.Giulia Brancaa, Debora Ferria, Manuela Lanzafamea, Erica Gandolfia, Gianluca Guidaa, Tiziana Nardoa, E. Bottaa and Donata OrioliaaIstitute of Molecular Genetics (IGM) L.L. Cavalli Sforza, CNR, 27100 Pavia, ItalyThe multiprotein complex TFIIH is a key factor in transcription and nucleotide excision repair (NER) pathway. TFIIH malfunctioning results in distinct autosomal recessive disorders, including the cancer-prone xeroderma pigmentosum (XP) and the multisystemic trichothiodystrophy (TTD), the latter one being characterized by physical and mental retardation, signs of premature ageing, but no skin cancer. Both XP and TTD cells are characterized by hypersensitivity to UV irradiation, persistence of NER proteins at the site of damage and accumulation of unrepaired DNA lesions. We have shown that TTD more than XP cells suffer of wide transcription deregulations. Whether this is accountable to TFIIH malfunctioning caused by TTD-specific mutations or to the findings that all TTD-causing mutations affect the stability of the entire complex and result in reduced TFIIH amount, is still an open question. The finding that TFIIH stabilization by low temperature or chemical treatment partially recover TFIIH functionality in primary cells from thermo-sensitive TTD cases (whose clinical features worsen with fever episodes), suggested to us the relevance of preserving TFIIH amount in human cells. We have now identified a novel TFIIH-containing multiprotein assembly bound to the chromatin, whose function is to assists RNA polymerase II during transcription. Reduced levels of wild-type TFIIH or other components of the protein assembly lead to transcription alterations similar to those observed in TTD. Overall, our findings demonstrate that quantitative, as well as qualitative, TFIIH alterations contribute to the wide spectrum of TTD clinical features.Kenneth H. Kraemer1, Deborah Tamura2, Sikandar G. Khan, John J. DiGiovanna31Lab of Cancer Biology and Genetics, NCI, NIH, Bethesda, MD, USA emeritus2retired3deceasedStudies of xeroderma pigmentosum (XP) began at NIH in 1971 to gain insights into clinical disease and mechanisms of DNA damage and repair. Detailed clinical and lab exams of skin and eye abnormalities, neurologic degeneration, hearing loss, skin and internal cancers, and aging were performed. We collaborated within NIH and with extra-mural scientists. Findings included discovery of 5 excision repair (ER) deficient XP complementation groups, the ER proficient XP variant, and measuring the > 1,000-fold increase in skin and eye cancer. We developed host cell reactivation assays for UV survival and mutagenesis and found that one DNA dimer inactivated expression in XPA cells. XP patients treated with oral retinoids provided the first demonstration of effective cancer chemoprevention in humans. Audiograms were used to assess the rate of XP neurological degeneration. Autopsies revealed infantile brains in adult XP patients attesting to the massive atrophy caused by XP. Internal cancers include brain and spinal cord neoplasms, thyroid cancer, leukemia, lymphoma and lung cancer (in smokers). Premature menopause, a feature of aging, was observed (median age 29.5 years was > 20 years younger than in the U.S. population). We found XPA patients with severe, intermediate, or mild disease. Trichothiodystrophy (TTD) patients with mutations in the XPD gene had abnormal development including absent myelin in their brain, multiple infections, bone abnormalities, aseptic necrosis of the hips and premature death but no increase in skin cancer. Mothers of TTD children with XPD mutations had many pregnancy abnormalities while mothers of XP children with XPD mutations had normal pregnancies thereby linking XPD function with human fetal development. We found two new RNA related TTD causing genes: TFIIE2 and DBR1. With Dr V. Bohr in 1985 we established the DNA Repair Interest Group with monthly videoconferences (several hundred archived at http://videocast.nih.gov) and initiated the first 3 of this series of international XP meetings (in 2004, 2006, and 2010). These intensive investigations of XP at NIH and worldwide have resulted in advances in understanding disease mechanisms and, most importantly, in increasing patient wellbeing and prolonging their life expectancy.Dr. R. SarkanyConsultant Dermatologist, UK XP National Service, LondonThe most common cause of premature death in XP is metastatic skin cancer (1) and 80% of skin cancers of XP are on the face, head and neck (2). So rigorous and absolute photoprotection from ultraviolet is crucial in the management of patients with XP, particularly of the face.We have recently used a new methodology to accurately estimate the daily dose of UV reaching the skin of the face over a prolonged period, and used this to study photoprotection behaviour in detail over a 3 week period in 36 XP patients in the UK. We found a wide range of UV protection (i.e. of daily UV dose to the face), with around 35% of adult XP patients protecting significantly more poorly than the rest (3). We went on to demonstrate that poor photoprotection correlated closely with 9 variables, 7 of which were potentially reversible psychological factors (4).We went on to design a personalised behaviour change intervention (‘XPAND’) to target these psychological factors shown to correlate with poor photoprotection (i.e. high daily UV dose to the face). It involves 7 one-to-one sessions delivered by a nurse or a psychologist.In this lecture I present the results of our randomised controlled trial of this intervention in 16 XP patients with poor photoprotection. The design was a two-arm parallel group randomised control trial with a delayed intervention control arm who received XPAND the following year. The primary endpoint was the mean daily UV dose to the face during a 3 week period in June or July following XPAND (or no intervention in the control group).Of 16 patients randomised, 13 provided sufficient data for primary outcome analysis. The XPAND group (n = 8) had a lower mean daily UV dose to the face than the control group (p<0.001). The delayed intervention control group also had a lower mean daily dose to the face after the intervention than before, but not at a statistically significant level. Secondary endpoints were also analysed. Health economic analysis was also carried out and predicted that XPAND was a cost-effective treatment, by reducing long term treatment costs associated with UV exposure.In this talk I will discuss these data, what can and what cannot be concluded from this small randomised controlled trial, and the implications for clinical management of XP.Alain Sarasin1, Andrey A. Yurchenko2 and Sergey Nikolaev21UMR9019 CNRS, Gustave Roussy and Paris-Saclay University, Villejuif, France2INSERM U981, Gustave Roussy and Paris-Saclay University, Villejuif, FranceXeroderma pigmentosum (XP) is a rare, autosomal, recessive genodermatosis caused by Excision Nucleotide Repair (NER) deficiency. These patients are extremely sensitive to sunlight leading to an increased frequency of skin cancers on exposed body sites. Due to constant photoprotection and better therapeutic education, XP patients live longer than in the past. Recently, it was found that some XP patients are at a very high risk of developing internal tumors, including central nervous systems, hematological malignancies, gynecological and thyroid cancers (Nikolaev et al., Orphanet J. Rare Dis., 2022, 17, 104).We analyzed four published, international, clinically well-defined XP cohorts (from the States, France, England and Brazil) and calculated the cancer risk of these patients. The Odds Ratio (OR) are very high for young XPs (more than a thousand times higher than for the general population) for the 0-20-year-old French XPs. Very high OR are also observed for English, French, and American XPs for developing brain tumors, hematological malignancies, and thyroid tumors. Among XP patients, the most susceptible to developing internal tumors are the patients from the XP-C group, particularly those who bear the founder XPC mutation from North Africa (Sarasin et al., Blood, 2019, 133,2718; Sarasin, Cancers, 2023, 15, 2706).We analyzed, by whole genome sequencing, 22 internal tumors from XP patients, mainly hematological malignancies, gynecological and thyroid tumors. Results demonstrated a dramatic increase in mutation rates in XP-C tumors versus sporadic tumors. A strong mutational asymmetry with respect to transcription and level of gene expression demonstrated the existence of transcription-coupled repair in vivo in humans. Mutations appeared to be caused by unrepaired bulky guanine lesions on the untranscribed strands of DNA (Yurchenko et al., Nature Comm., 2020, 11, 5834; Yurchenko et al., Commun Med, 2023, 3, 109). The mutational profiles of internal XP-C tumors are very specific to NER-deficiency and nearly identical between all XP-C internal tumors regardless of the tumor type, and completely different from the tissue-matched sporadic tumors.Physicians following XP patients should be aware of the high risk of internal tumors. Prevention and early detection of leukemia and brain, gynecological, and thyroid tumors are needed. Screening should be done every year starting around the age of 10–12 years (for example, early anemia occurs several years before MDS/ leukemia in some XP-C patients).Diana van den Heuvel1,11, Marta Rodríguez-Martínez2,11, Paula J. van der Meer1,11, Nicolas Nieto Moreno3, Jiyoung Park4, Hyun-Suk Kim4, Janne J.M. van Schie1, Annelotte P. Wondergem1, Areetha D'Souza4, George Yakoub1, Anna E. Herlihy2, Krushanka Kashyap3, Thierry Boissière2,3, Jane Walker2, Richard Mitter6, Katja Apelt1, Klaas de Lint7, Idil Kirdök7, Mats Ljungman8,9, Rob M.F. Wolthuis7, Patrick Cramer10, Orlando D. Schärer4,5, Goran Kokic10,12, Jesper Q Svejstrup2,3,12, Martijn S. Luijsterburg1,121Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands2Mechanisms of Transcription Laboratory.3Department of Cellular and Molecular Medicine, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen, Denmark.4Center for Genomic Integrity, Institute for Basic Science, Ulsan, Republic of Korea5Department of Biological Sciences, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea6Bioinformatics and Biostatistics, The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK.7Department of Clinical Genetics, Section Oncogenetics, Cancer Center Amsterdam, Amsterdam University Medical Center, Amsterdam, the Netherlands8Department of Radiation Oncology, University of Michigan, Ann Arbor, MI, USA9Department of Environmental Health Sciences, Rogel Cancer Center and Center for RNA Biomedicine, University of Michigan, Ann Arbor, MI, USA10Max Planck Institute for Multidisciplinary Sciences, Department of Molecular Biology, 37077 Göttingen, Germany.11 These authors contributed equally12 Senior authorsTranscription-coupled DNA repair (TCR) removes bulky DNA lesions impeding RNA polymerase II (RNAPII) transcription. Recent studies have outlined the stepwise assembly of TCR factors CSB, CSA, UVSSA, and TFIIH around lesion-stalled RNAPII. However, the mechanism and factors required for the transition to downstream repair steps, including RNAPII removal to provide repair proteins access to the DNA lesion, remain unclear. Here, we identify STK19 as a TCR factor facilitating this transition. Loss of STK19 does not impact initial TCR complex assembly or RNAPII ubiquitylation but delays lesion-stalled RNAPII clearance, thereby interfering with the downstream repair reaction. Cryo-EM and mutational analysis reveal that STK19 associates with the TCR complex, positioning itself between RNAPII, UVSSA, and CSA. The structural insights and molecular modeling suggest that STK19 positions the ATPase subunits of TFIIH onto DNA in front of RNAPII. Together, these findings provide new insights into the factors and mechanisms required for TCR.","PeriodicalId":14758,"journal":{"name":"Journal Der Deutschen Dermatologischen Gesellschaft","volume":"23 S2","pages":"3-20"},"PeriodicalIF":5.5000,"publicationDate":"2025-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/ddg.15735_g","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal Der Deutschen Dermatologischen Gesellschaft","FirstCategoryId":"3","ListUrlMain":"https://onlinelibrary.wiley.com/doi/10.1111/ddg.15735_g","RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"DERMATOLOGY","Score":null,"Total":0}

引用次数: 0

Rupesh Paudel^1,2*, Lena F Sorger^1*, Anita Hufnagel¹, Mira Pasemann¹, Tamsanqa Hove^1,3, André Marquardt^1,4, Susanne Kneitz⁵, Andreas Schlosser⁶, Caroline Kisker³, Jochen Kuper^3#, Svenja Meierjohann^1,4#

¹Institute of Pathology, University of Würzburg, 97080 Würzburg, Germany

²Department of Dermatology, Venereology and Allergology, University Hospital Würzburg, 97080 Würzburg, Germany.

³Rudolf Virchow Center for Integrative and Translational Bioimaging, Institute for Structural Biology, University of Würzburg, 97080 Würzburg, Germany

⁴Comprehensive Cancer Center Mainfranken, University of Würzburg, 97080 Würzburg, Germany

⁵Department of Biochemistry and Cell Biology, University of Würzburg, 97074 Würzburg, Germany

⁶Rudolf Virchow Center for Integrative and Translational Bioimaging, Mass Spectrometry Division, University of Würzburg, 97080 Würzburg, Germany

^#corresponding authors:

J Kuper ([email protected])

S Meierjohann ([email protected])

*These authors contributed equally to this work

Abstract

Germline mutations in the DNA repair helicase XPD cause the diseases xeroderma pigmentosum (XP), trichothiodystrophy (TTD) and Cockayne syndrome. XP patients bear an increased risk of developing skin cancer including melanoma, even at young age. This is not observed for TTD patients despite DNA repair defects. To examine whether TTD cells harbor features counteracting tumorigenesis, we developed a TTD melanoma cell model containing the XPD variant R722W. Intriguingly, TTD melanoma cells exhibited reduced pro-tumorigenic features and an increased signature of the melanocyte lineage differentiation factor MITF, which went along with a strong basal upregulation of REDD2, an inhibitor of the mTOR/S6K/4EBP1 dependent protein translation machinery. REDD2 levels were partially driven by MITF, increased under UV exposure, and contributed to the reduced melanoma proliferation. To investigate whether similar processes are affected in melanocytes - the progenitor cell type of melanoma - we developed a TTD melanocyte model. Again, the MITF gene signature was increased, this time without affecting REDD2 expression. However, protein translation analyses revealed reduced ribosomal protein synthesis particularly in R722W melanocytes after UV stress, indicating a compromised protein translation machinery. Impaired protein translation was also demonstrated for the TTD XPD variant A725P, but not for the XPD variant D234N that causes XP. Concludingly, although effectors of R722W partially differ between melanoma cells and melanocytes, they result in translation inhibition and therefore reduced fitness, particularly under UV exposure. This may limit the probability of UV-driven tumorigenesis and offers an explanation why TTD patients do not develop melanomas.

Gaia Veniali¹, Anita Lombardi¹, Massimo Teson², Tiziana Nardo¹, Elena Botta¹, Elena Dell'Ambra², Donata Orioli¹, Manuela Lanzafame¹

¹CNR-Istituto di Genetica Molecolare, Pavia, Italy

²Istituto Dermopatico dell'Immacolata (IDI), Rome, Italy

Nucleotide Excision Repair (NER) is the only DNA repair system in humans dedicated to removing bulky DNA adducts induced by ultraviolet (UV) radiations. NER defects are responsible for the inherited disorder xeroderma pigmentosum (XP), which is characterized by high predisposition of developing melanoma and non-melanoma skin cancers due to the accumulation of unrepaired UV-induced DNA lesions. Interestingly, mutations in the NER-related genes XPB or XPD can also cause trichothiodystrophy (TTD), another rare disorder characterized by NER defects. However, unlike XP, TTD patients do not develop cancer but are characterized by hair abnormalities, pre- or post-natal growth failure, neurodevelopmental and neurological dysfunctions, signs of premature aging. Investigations and comparative gene expression profile studies on skin cells from XP and TTD patients carrying mutations in the same gene, offer a promising tool for identifying molecular pathways that drive or counteract skin carcinogenesis.

Whole-transcriptome analysis has been performed on our collection of primary skin fibroblasts and keratinocytes from XPD-mutated patients. We found disease-specific expression signatures, with XP cells showing a tumor-like profile characterized by the upregulation of genes involved in inflammation and extracellular matrix remodeling, whereas TTD cells exhibit an anti-tumor signature marked by the upregulation of tumor suppressor genes and the downregulation of oncogenic pathways.

The relevance of the identified transcription deregulations on skin cancer pathophysiology is currently under investigation by silencing or overexpressing the genes of interests in control skin cells and taking advantage of three-dimensional (3D) culture models that mimic critical aspects of solid cancers, including mechanical regulation of growth, hypoxia, and invasiveness. Our preliminary data on melanoma spheroids indicate that specific gene expression deregulations in the tumor microenvironment influence melanoma invasiveness.

Overall, our findings indicate that XP and TTD patient-derived primary skin cells, sharing mutations in the same gene but exhibiting opposite skin cancer susceptibilities, provide an exceptional framework for uncovering the molecular mechanisms underlying skin carcinogenesis and identifying novel targets for therapeutic intervention.

Ubiquitylation plays a crucial role in Nucleotide Excision Repair (NER). In the subpathway Global Genome NER (GG-NER), XPC detects lesions genome wide, with its activity enhanced after ubiquitylation by CRL4^DDB2. Conversely, Transcription-Coupled NER (TC-NER) is restricted to the transcribed strand of active genes, initiated by recognition of the lesion-stalled RNA Polymerase II (RNAPII) by CSB and subsequent recruitment of CSA, the substrate recognition subunit of CRL4^CSA. Ubiquitylation of RNAPII by CRL4^CSA at lysine 1268 (K1268) of its RPB1 subunit was previously shown to be important for TC-NER. Moreover, RPB1 K1268 ubiquitylation suppresses global gene expression by inducing RPB1 degradation, lowering RNAPII levels.

Intriguingly, however, cells defective in TC-NER still display robust RPB1 ubiquitylation after DNA damage but do not degrade RPB1. This led us to speculate that ubiquitylated RPB1 (ubi-RPB1) might have alternative, non-degradative roles. As ubi-RPB1 is only a small fraction of total RPB1 in the cell, we developed a strategy based on sequential enrichment steps followed by mass-spectrometry to study its interactome. For these experiments, we used an RPB1-K1268R mutant as a control to identify factors that specifically associate with ubiquitylated RPB1. This approach revealed a number of unexpected, high-confidence interactors, that led us to uncover a novel signaling pathway with major implications for Nucleotide Excision Repair.

Debora Ferri^a,*, Giulia Branca^a,*, Manuela Lanzafame^a, Erica Gandolfi^a, Valentina Riva^a, Giovanni Maga^a, Claudia Landi^c, Luca Bini^c, Lavinia Arseni^a, Fiorenzo A. Peverali^a, Emmanuel Compe^b and Donata Orioli^a

^aIstituto di Genetica Molecolare (IGM) L.L. Cavalli Sforza, CNR, 27100 Pavia, Italy;

^bInstitut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Illkirch Cedex 67404, Strasbourg, France;

^cDepartment of Life Sciences, University of Siena, 53100 Siena, Italy.

*Equal contribution

Abstract

The transcription factor IIH (TFIIH) is a ten-subunits complex organized in two sub-complexes, the ternary CDK activating kinase (CAK) and the hexameric core-TFIIH, bridged together by the XPD subunit. TFIIH is involved in different cellular mechanisms such as basal transcription, gene expression regulation and nucleotide excision repair (NER), the DNA repair pathway that specifically removes the bulky DNA adducts induced by ultraviolet (UV) light or other genotoxic agents. Mutations in the ERCC2/XPD gene are responsible for different clinical conditions, including the cancer-prone xeroderma pigmentosum (XP) and the photosensitive form of trichothiodystrophy (PS-TTD), a cancer-free neurodevelopmental disorder. At the cellular level, all XPD mutations result in NER defects and accumulation of unrepaired DNA photolesions. Furthermore, mutations specifically associated to PS-TTD clinical features also lead to reduced TFIIH cellular amount and transcription deregulations. Recently, our laboratory has demonstrated that PS-TTD more than XP primary dermal fibroblasts suffer of wide transcriptional impairments that, in some cases, result in altered protein content contributing to PS-TTD clinical features. To accomplish its function in DNA repair and transcription, TFIIH requires a direct interaction with the chromatin and relies on the presence of both the CAK and core sub-complexes. In the present study, we investigate the impact of XPD mutations on the association/dissociation of the two sub-complexes and their interaction with the chromatin.

Immunoprecipitation of the chromatin-bound CAK followed by mass spectrometry analysis identifies TFIIH as part of a large multiprotein assembly that assists RNA polymerase II during mRNA synthesis. PS-TTD causing mutations alter the relationships of TFIIH with other components of the protein assembly and give rise to transcriptional stress. Overall, this study sheds light on a still unknown function of TFIIH during transcription, whose impairment contributes to the wide transcriptional defects underlying PS-TTD pathological condition.

Alexandra Paolino¹, Ruth Keogh², Sinéad M. Langan², Alan R. Lehmann³, Isabel Garrood¹, Hiva Fassihi¹

¹National Xeroderma Pigmentosum Service, Department of Photodermatology, St John's Institute of Dermatology, Guy's and St Thomas’ Foundation Trust, London SE1 7EH, United Kingdom.

² Department of Non-communicable Disease Epidemiology, London School of Hygiene and Tropical Medicine, London, WC1E 7HT, United Kingdom.

³ Genome Damage and Stability Centre, University of Sussex, Falmer, Brighton BN1 9RQ, United Kingdom.

Introduction: Xeroderma pigmentosum (XP) is a rare autosomal recessive disorder of DNA repair, characterized by extreme sensitivity to ultraviolet radiation. Patients are at risk of skin cancers, ocular surface disease, and approximately one-third of patients experience progressive neurodegeneration. Life expectancy varies significantly based on complementation group, disease severity, and access to preventive measures. Obtaining reliable survival estimates for this rare and genetically heterogeneous disease can be challenging, leading to variability in reported survival rates. A National Institutes of Health study of 106 patients (1971 to 2009) reported a median age at death of 29 years for XP patients with neurodegeneration and 37 years for those without (1). These statistics are frequently cited in academic literature and widely reported on publicly accessible websites.

Aim: To assess the life expectancy of XP patients receiving multidisciplinary care at the UK National XP Service and assess patients and families understanding of their prognosis.

Methods: We conducted a longitudinal study of 89 patients examined and treated annually in the UK National XP Service from 2015 to 2024. Mortality events were documented and categorised between those with and without neurodegeneration. To evaluate patient perceptions on life expectancy, 24 clinic attendees (16 neurologically unaffected patients and eight relatives) completed a short survey prior between February and July 2023.

Results: Over a 9-year period, we recorded 15 deaths (17%), comprising 11 cases with neurodegeneration (groups A, B, D, F, and G) and 4 cases without neurodegeneration (groups A, C and V). Notably, there were no deaths attributable to skin cancer. Four deaths were linked to internal malignancies [median age: 52.5 years (IQR 41.8-58.75). The median survival age is 50 years (95% CI [34, Inf]) for those with neurological involvement, and 81 years (95% CI [81, Inf]) for those without. The latter is comparable to the general UK population (78.6 years for males, 82.6 years for females, 2020–2022) (2). The estimated probability of survival beyond age 40 is 0.68 (95% CI [0.47,0.98]) for individuals with neurological involvement and 0.90 (95% CI [0.73,1.00]) for those without.

Only 11 of 24 survey respondents (46%) believed that life expectancy in neurologically unaffected XP patients was normal. One respondent (4%) estimated life expectancy at 20-29 years, 8 (31%) at 30-39 years, 1 (4%) at 50-59 years, and 3 reported uncertainty.

Conclusion: We present evidence of improved survival outcomes in patients with XP in the UK, both with and without neurological involvement, compared to previously reported literature. While life expectancy for individuals with XP can be limited, particularly without appropriate care, advances in medical management and strict adherence to preventive measures have improved outcomes. It is important that outdated and potentially harmful misinformation online is updated and to convey to through discussions with patients and families that regular medical follow-ups, diligent photoprotection, and timely intervention for skin cancers, can enhance both longevity and quality of life for those affected by XP.

REFERENCES:

Bradford PT, Goldstein AM, Tamura D, Khan SG, Ueda T, Boyle J, Oh KS, Imoto K, Inui H, Moriwaki S, Emmert S, Pike KM, Raziuddin A, Plona TM, DiGiovanna JJ, Tucker MA, Kraemer KH. Cancer and neurologic degeneration in xeroderma pigmentosum: long term follow-up characterises the role of DNA repair. J Med Genet. 2011 Mar;48(3):168-76. doi: 10.1136/jmg.2010.083022. Epub 2010 Nov 19. PMID: 21097776; PMCID: PMC3235003.

Office for National Statistics (ONS), released 11 January 2024, ONS website, statistical bulletin, National life tables – life expectancy in the UK: 2020 to 2022

Alexandra Paolino¹, Sally Turner¹, Tanya Henshaw¹, Joanne Palfrey¹, Karla Balgos¹, Paola Giunti, Ana M. S. Morley¹, Shehla Mohammed¹, Adesoji Abiona¹, Alan R. Lehmann², Hiva Fassihi¹

¹National Xeroderma Pigmentosum Service, Department of Photodermatology, St John's Institute of Dermatology, Guy's and St Thomas’ Foundation Trust, London SE1 7EH, United Kingdom;

²Genome Damage and Stability Centre, University of Sussex, Falmer, Brighton BN1 9RQ, United Kingdom.

Introduction: There is marked heterogeneity in the presenting clinical features of Xeroderma Pigmentosum (XP), both between and within complementation groups. Effective management relies on early diagnosis, stringent photoprotection to mitigate skin cancer-related morbidity and mortality, and regular dermatological and ophthalmological examinations to detect and treat malignancies promptly. Despite these measures, delays in diagnosis remain a challenge, emphasizing the need for increased awareness among healthcare providers.

Aim: To evaluate presenting clinical features of XP and time from first symptom onset to diagnosis.

Methods: A retrospective review was conducted on 133 XP patients (67 females, 66 males; age range 0–87 years) receiving specialist multidisciplinary care at a national centre. Of these, 100 patients were included in the study, excluding 29 diagnosed through older siblings and 4 with incomplete histories. Data collected included complementation group, presenting clinical features categorised into dermatological, ophthalmological, or neurological signs, age of symptom onset, age at diagnosis, and referring specialty.

Results: The complementation groups represented included XP-A (n = 20), XP-B (n = 2), XP-C (n = 29), XP-D (n = 14), XP-E (n = 6), XP-F (n = 6), XP-G (n = 7), XP-V (n = 16). By age 3, 84% of patients had developed clinical signs of the condition (excluding those presenting with skin cancers), yet the mean age at diagnosis was 12.2 years (median 6; range 0.5–64 years).

Initial clinical signs varied significantly. Exposed-site pigmentary changes appeared at a mean age of 5 years (range 0.5–44 years) and were predominantly observed in XP-C (83%, mean age 2.3 years, range 0.75–6 years) and XP-V (56%, mean age 14.4, range 2–44) patients.

Photosensitivity, characterised by severe prolonged sunburn, was the primary symptom in XP-D (100%), XP-F (100%), XP-G (86%), and XP-A (55%) patients, excluding those with the milder XP-A variant. Median diagnostic delays were shorter in these complementation groups (range 3.2-11 years).

Skin cancers at presentation were most common in XP-E (66%, mean age 26 years, range 15–40), XP-V (44%, mean age 35 years, range 16–46) and XP-C (7%, mean age 16 years, range 4–28 years).

Ocular signs, including conjunctivitis and photophobia were the first presenting features in two XP-C patients aged 0.5 and 1 year. Neurological symptoms were the initial presenting feature in two XP-A patients who exhibited developmental delays by age two.

Diagnostic delays were particularly pronounced in XP-E and XP-V patients, with median delays of 28.5 and 21.5 years, respectively. Dermatologists were the most frequent referrers, accounting for 73% of referrals, followed by geneticists (7%), general practitioners (10%), paediatricians (5%), neurologists (3%) and ophthalmologists (2%).

Conclusion: Most XP patients exhibit clinical signs early in life, but significant diagnostic delays exist, particularly in groups with milder cutaneous manifestations where severe sunburn reactions or pigmentary changes are lacking. Dermatologists are the primary referrers, underscoring their critical role in early recognition. Increased awareness across all specialties is essential to improve diagnostic timelines and outcomes for XP patients.

Guzzon Diletta^1*, Paccosi Elena^1*, Filippi Silvia¹, Valeri Emma¹, De Lanerolle Primal² and Proietti-De-Santis Luca^1#

¹Unit of Molecular Genetics of Aging, Department of Ecology and Biology (DEB), University of Tuscia, 01100 Viterbo, Italy.

²Department of Physiology and Biophysics, College of Medicine, University of Illinois at Chicago, 835 S. Wolcott, Chicago, IL 60612.

Cockayne Syndrome group A (CSA) is an ubiquitin E3 ligase belonging to the family of WD-40 repeat proteins. CSA was initially characterized, together with Cockayne syndrome group B (CSB) protein, as playing a role in Transcription Coupled Repair even if, in the last years, a growing body of evidence shows how this protein, together with CSB, exerts a key role in the regulation by ubiquitination and proteasomal degradation of a plethora of different proteins involved in the most disparate cellular processes. Mutations in CSA, as well as in CSB, result in Cockayne syndrome (CS), a human autosomal recessive disorder characterized by a variety of clinical features, including growth deficiency and severe neurological and developmental manifestations.

Actin, a major component of the cytoplasm, has been recently described as abundant in its filamentous form (F-Actin) also in the nucleus, where it is involved in a variety of nuclear processes including transcription and chromatin remodeling. The nuclear export of Actin is mediated by Chromosomal Maintenance 1 or Exportin 1 (CRM1). Here, we demonstrate that CSA may regulate the nuclear localization of Actin by ubiquitinating its nuclear exporter CRM1, in such a manner to avoid the passage of CRM1/Actin complexes through the nuclear pore complex. We also demonstrate that CS-A patients derived fibroblasts display a hampered Actin nuclear retention, in favour of its nuclear export, as a consequence of a defective CRM1 ubiquitination. This unbalance in Actin localization results in both an altered and stiff cytoskeletal shape and in a drastic reduction of nuclear Actin foci. Furthermore, while normal cells display a preferential localization of CRM1 on the nuclear membrane, CS-A mutant cells show, instead, an aberrant presence of CRM1 as cytoplasmic foci, further confirming an abnormal rate of CRM1-mediated export. How to reconcile this defective export of nuclear Actin with Cockayne syndrome features? It is well known that nuclear Actin localizes at the promoters of certain genes, where it helps the recruitment or RNA polymerase II (RNA polII). Interestingly, in CS-A mutated patient's derived fibroblasts, we found a hampered recruitment of Actin on promoters of some genes, such as BDNF and BRD7 ones, corresponding to a defective recruitment of RNA polII on the same promoters and to a defective transcription of these genes. These results may potentially justify the transcriptional defects shown by CS-A patients, especially regarding the neurodevelopmental manifestations.

It is still to determine if also CSB is someway involved in this new regulatory pathway, maybe being responsible of the degradation of the nuclear exporter protein CRM1. Further studies will be required to better define both the eventual role of CSB and the consequences of the impairment of Actin shuttling on the clinical features of CS patients.

Silvia Filippi, Emma Valeri, Elena Paccosi, Diletta Guzzon and Luca Proietti De Santis

Unit of Molecular Genetics of Aging, Department of Ecology and Biology (DEB), University of Tuscia, 01100 Viterbo, Italy.

Cockayne syndrome (CS), defined as Nucleotide excision repair (NER) syndrome, is a rare autosomal recessive disorder linked to mutations in ERCC8 and ERCC6 genes, which encode for CS group A (CSA) and group B (CSB) proteins respectively, both of which play a role in Transcription Couples repair (TCR), a sub-pathway of NER, devoted to removal of lesions on transcribed genes. Although CS patients exhibit hypersensitivity to UV irradiation, they do not experience an increased risk of skin cancer occurrence in contrast to another NER syndrome defined as Xeroderma pigmentosum. While a loss-of-function mutation in the ERCC8 and ERCC6 genes causes a variety of senescence- and cell death-related abnormalities, increased expression of CSA and CSB proteins has been reported in cancer cells from different tissues often associated with increased proliferation and cell robustness. Recently, we demonstrated that CSA protein is over-expressed in breast cancer cells and its down-regulation by ASO technology dramatically reduces not only the tumorigenicity but also enhances the sensitization of BC cells to both oxaliplatin and paclitaxel drugs, two of the major chemotherapy agents used for triple-negative breast subtype. In this line, we decided to analyze the CSA expression in primary (WM115) and metastatic (WM266-4) melanoma cells. Melanoma is the most aggressive form of skin cancer. Research has made a great stride, in the last years, trough the introduction of innovative and effective therapies: immunotherapy and target therapy, unfortunately, some types of melanomas are refractory to therapeutic treatments. In this case, conventional chemotherapy with methylating agents: Dacarbazine (DTIC) and Temozolomide (TMZ) is considered as a last-line option. Both DTIC and TMZ are associated with unclear survival benefits and treatment-related toxicities. Our studies demonstrated that both WM115 and WM266-4 cells display an overexpression of CSA. Furthermore, CSA suppression greatly sensitizes both cell lines, in particular the metastatic ones, to both Dacarbazine (DTIC) and Temozolomide (TMZ) drugs, even at very low doses which are not harmful to normal cells, in term of cell proliferation, cell survival and apoptotic response. Further, studies are mandatory to evaluate whether CSA may be considered a very attractive target for the development of more effective antimelanoma therapies.

Julie Soutourina

Institute for Integrative Biology of the Cell (I2BC), CEA - CNRS - University Paris-Saclay, 91191 Gif-sur-Yvette France

Transcription and DNA repair are fundamental functions of the cell. Their dysfunctions lead to cell death, mutagenesis and pathologies. In NER, transcription-coupled repair removes DNA lesions interfering with RNA polymerase II progression. Inherited NER defects lead to xeroderma pigmentosum, Cockayne syndrome and triochothiodystrophy with complex syndromes including sunlight sensitivity, skin cancer or premature aging and neurological symptoms. Mediator is an essential and conserved multisubunit coactivator complex. In human, neurodevelopmental diseases mapped to Mediator mutations were regrouped as Mediatorpathies. New Mediator variants were recently uncovered in patients with transcription and TCR defects. However, many questions remain unanswered on mechanisms of complex diseases related to transcription and NER deficiencies.

The yeast Saccharomyces cerevisiae offers a unique opportunity to unveil the fundamental eukaryotic mechanisms thanks to its powerful genetic and genomic tools. Our work contributed to understanding of Mediator transcription function. Moreover, we have discovered its novel role by connecting transcription and NER via Rad2, the yeast homolog of human XP/CS-related XPG. Taking advantage of yeast, we transposed pathological Mediator mutations associated with CS-like symptoms and showed that they led to growth and UV-sensitivity phenotypes, and genetic interactions with TCR components. We are characterising their impact on physical interactions with Pol II and Rad2, transcription and DNA repair.

Transcription also affects mutagenesis and DNA repair prevents mutations responsible for aging and diseases. However, mechanisms involved in mutagenesis associated with transcription and DNA repair remain to be fully understood. Recently, we developed an innovative microfluidic-based system, coupled with high-throughput sequencing, for mutation accumulation in yeast. We transposed XP, CS or TTD-associated mutations and are analysing their impact on mutagenesis using our microfluidic-based and reporter-gene approaches combined with mutagen treatments.

In conclusion, we propose how the yeast model can give important insights into our understanding of the molecular mechanisms at the origin of complex human diseases related to transcription and NER deficiencies.

Philipp-Kjell Ficht¹, Anna Staffeld¹, Wilhelm Sponholz¹, Rüdiger Panzer¹, Anneke Lemken¹, Nataliya DiDonato², Joseph Porrmann², Mensuda Hasanhodzic³, Ales Maver⁴, Tasja Scholz⁵, Maja Hempel⁵, Oleksandra Kuzmich⁶, Steffen Emmert¹, Lars Boeckmann¹

¹Clinic and Policlinic for Dermatology and Venereology, University Medical Center Rostock, Germany

²Institute for Clinical Genetics, University Hospital Carl Gustav Carus at the Technische Universität Dresden, Germany

³Department of endocrinology, metabolic diseases and genetics University Clinical Centre Tuzla, Bosnia and Herzegovina

⁴Centre for Mendelian Genomics, Clinical Institute of Medical Genetics, UMC Ljubljana, Slovenia

⁵Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany

⁶DWI - Leibniz Institute for Interactive Materials e. V., Aachen, Germany

Xeroderma pimentosum (XP) is an autosomal recessive disorder characterized by increased photosensitivity, actinic skin damage, neurological abnormalities, and an elevated risk of skin and mucosal cancers. This condition is caused by defects in genes encoding for components of the nucleotide excision repair (NER) pathway. In this study, genetic and functional analyses were performed on patients with a suspected clinical diagnosis of XP or those identified with mutations in an XP-related gene. For patients with an unknown genetic cause, DNA sequencing was conducted to determine the underlying genetic defect. Additionally, functional analyses of patient cells were performed to assess their repair capacity and survival rates following UV-C irradiation. Exome or Sanger sequencing revealed identical compound heterozygote mutations in ERCC2 (XPD) in two patients, one patient with a homozygous missense variant in DDB2 (XPE), one with a homozygous single nucleotide variant in XPA and one with a homozygous mutation in XPC. Sequencing of DNA from two further patients is currently conducted. The presents of a heterozygous variant in one of the parents was confirmed for the patients with a homozygous variant in XPA or XPC. The exposure of patient derived fibroblasts to UV-C irradiation showed no reduced post-UV-survival compared to wild type cells for cells from patients with genetic alteration in ERCC2 or DDB2, a slightly reduced post-UV-survival for XPC and no reduced post-UV-survival for cells with alterations in XPA. Preliminary results of a host cell reactivation assay (HCR) showed that the reduced DNA repair capacity of cells with a defect in DDB2 could be compensated by the transfection of the cells with wild type DDB2. No compensation was observed for cells with alterations in ERCC2. Hair analyses for patients with compound heterozygous mutations in ERCC2 showed neither a reduced cysteine content nor the typical tiger-tail pattern as seen in a patient with trichothiodystrophy (TTD) under polarized light microscopy. Overall this ongoing study characterizes and correlates the genotypes and phenotypes of seven patients with varied clinical symptoms.

Lars Boeckmann¹, Philipp Ficht¹, Anna Staffeld¹, Rüdiger Panzer¹, Steffen Emmert¹

¹Clinic and Policlinic for Dermatology and Venereology, University Medical Center Rostock, Germany

The nucleotide excision repair (NER) is essential for the repair of ultraviolet (UV)-induced DNA damage, such as cyclobutane pyrimidine dimers (CPDs) and 6,4-pyrimidine-pyrimidone dimers (6,4-PPs). Alterations in genes of the NER can lead to NER-defective syndromes. The main NER-defective syndromes comprise xeroderma pigmentosum (XP), Cockayne syndrome (CS), and trichothiodystrophy (TTD).

Clinical and molecular-genetic assessment of XP-C patients from Germany revealed absence of sun-sensitive as well as neurological symptoms. The mean age of XP diagnosis was 9.4 years, and the median age of the first skin cancer was 7 years. We identified five new mutations including an amino acid deletion (c.2538_2540delATC; p.Ile812del) resulting in repair deficiency but no XPC message decay.

Assessment of XPG-defective patients revealed that the type and location of mutations determine the clinical phenotype. We identified 3 missense mutations and showed by molecular means that these missense mutations in the I-region of the XPG protein impaired both repair and transcription and delayed the recruitment of other XP proteins to UV photodamage as well as their redistribution thereafter. The patients exhibited a XP/CS complex phenotype.

We also identified two XPG and XPF splice variants with residual repair capabilities in NER. Almost all variants are severely C-terminally truncated and lack important protein-protein interaction domains. Interestingly, XPF-202, differing to XPF-003 in the first 12 amino acids only, had no repair capability at all, suggesting an important role of this region during DNA repair.

German XPD-deficient patients exhibited a XP phenotype in accordance with established XP-causing mutations (c.2079G>A, p.R683Q; c.2078G>T, p.R683W; c.1833G>T, p.R601L; c.1878G>C, p.R616P; c.1878G>A, p.R616Q). One TTD patient was homozygous for the known TTD-causing mutation p.R722W (c.2195C>T). Two patients were compound heterozygous for a TTD-causing mutation (c.366G>A, p.R112H) and p.D681H (c.2072G>C) amino acid exchange, but exhibited different TTD and XP/CS complex phenotypes. Interestingly, the XP/CS patient's cells exhibited a reduced but well detectable mutated XPD protein expression compared with hardly detectable XPD expression of the TTD patient's cells.

Further genotype-phenotype studies could be performed within the European Reference Networks for Rare Diseases (ERN-Skin).

Francesca Brevi¹, Arjan Theil², Alan Lehmann³, Sebastian Iben⁴, Donata Orioli¹ and Elena Botta¹

¹Istituto di Genetica Molecolare (IGM) CNR, Pavia, Italy

²Department of Molecular Genetics, Erasmus MC, University Erasmus Medical Center, Rotterdam, The Netherlands

³Genome Damage and Stability Centre, University of Sussex, Falmer, Brighton, UK

⁴Department of Dermatology and Allergic Diseases, Ulm University, Ulm, Germany

Trichothiodystrophy (TTD) is a multi-system disease characterized by skin, neurological and growth abnormalities. The presence of photosensitivity defines the two main forms of TTD – the photosensitive (PS) and non-photosensitive (NPS) forms. Mutations in a variety of genes have been associated to the disease. They include three PS-TTD related genes that encode distinct subunits of the transcription/DNA repair factor TFIIH and seven NPS-TTD related genes encoding the beta subunit of transcription factor IIE -TFIIEβ, the splicing factors TTDN1 and RNF113A and four aminoacyl-tRNA synthetases which operate in translation. All these TTD-related factors participate in gene expression, thus raising the notion of TTD as a gene expression syndrome. It has been demonstrated that TTD-causing mutations in TFIIH subunits or TFIIEβ as well as knockout/knockdown of TTDN1 and RNF113A impact on transcription by RNA polymerase I. Consequently, ribosomal biogenesis is affected with concomitant error-prone translation and loss of protein homeostasis (proteostasis). Now, by taking advantage of our recently identified TTD cases mutated in methionyl-, threonyl- or alanyl-tRNA synthetase, we have investigated the quality of translation in tRNA synthetase-defective TTD cases. By using a luciferase-based assay, we found a high translation error rate in all tested TTD cells, indicating translation infidelity. In addition, survival assays in the presence of elevated concentrations of single specific amino acids suggested impaired accuracy of tRNA charging. These alterations are accompanied by accumulation of misfolded proteins, indicating a loss of proteostasis. Overall, translation infidelity and loss of proteostasis appear as a common underlying pathomechanism for the different forms of TTD, which may contribute to impaired development and neurodegeneration in patients.

Jordana McLoone^1,2, Kyra Webb², Kathy Tucker³, Antoinette Anazodo², Denise Wilson⁵, Linda Martin^1,4,5

¹UNSW Sydney, School of Clinical Medicine

²Kids Cancer Centre, Sydney Children's Hospital

³Hereditary Cancer Centre, Sydney Children's Hospital, UNSW

⁴Dept Dermatology, Sydney Children's Hospital

⁵Melanoma Institute Australia

Background: In Australia there are no dedicated diagnostic or management services for patients with xeroderma pigmentosum (XP).

Aim: To understand the supportive care needs of families who have a child diagnosed with XP.

Methods: Australian parents and carers of a child with XP, as well as children with XP 5–18 years with no intellectual disability were invited to participate. Participants were identified via clinical networks and social media patients support groups. A semi-structured interview was conducted in-person or via Zoom and focused on the diagnostic journey, current care, preferred models of care, psychosocial impact, and information needs. Interview data were transcribed verbatim and coded line-by-line using QSR NVivo Pro. Inductive thematic analysis was used to organize nodes and themes.

Results: Eight adult carers and 3 children with XP where interviewed, including one family with XP-A, one family with XP-C, and two families with XP-D. Five out of the seven families identified participated.

Most families had long delays before the diagnosis with misinterpretation of presenting symptoms. Wait times for genetic testing were 6–12 months. All families reported highly unmet informational needs, including how to sun protect, prognosis and management. Parents reported unmet psychological needs, including guilt, fear, grief, isolation and hypervigilance. Adaptions and sun protective requirements were costly.

The preferred model of care for patients was a multidisciplinary team that included dermatology, ophthalmology, neurology, and allied health. Continuity of care was emphasized.

Conclusion: The development of comprehensive clinical services to address the diagnostic, preventative, surveillance, treatment and supportive care needs of Australian XP patients is urgent.

Riccardo Paolini¹, Yvette Walker², T. Xiong¹, Konstantina Vasilakopoulou,¹ Linda Martin^3,4

¹UNSW School of Built Environment, Faculty of Art, Design & Architecture.

²UNSW Rare Diseases

³UNSW School of Clinical Medicine, Faculty of Medicine & Health.

⁴Sydney Children's Hospital

⁵Melanoma Institute Australia.

Background: Complete protection against all ultraviolent (UV) radiation requires individuals with xeroderma pigmentosum (XP) to wear highly protective garments, including a hood with a visor, full clothing, and gloves. Commercially available garments have been designed and tested for UV protection only, but may lead to substantial solar heat gains, resulting in human thermal discomfort, de facto restricting outdoor activity and impacting quality of life.

Objective: To test the effect on thermal properties with of the addition of solar control film to the XP visor (PS90 by 3M).

Methods: Surface temperature was measured with a thermal camera (T540 by FLIR). The optical properties of materials were characterised with a UV-Vis-NIR spectrophotometer with a 150 mm integrating sphere (Lambda 1050+ by Perkin Elmer), and the broadband properties (solar, uv, vis, and nir) were computed with the solar irradiance distribution of global horizontal radiation with air mass 1, following ASTM E903.

Results: The UV transmittance of the plain visor is zero in the 250-380 nm wavelength range, but there is some light transmission in the 380-400 nm range (from 0.02 at 385 nm to 0.64 at 400 nm), resulting in a total UV transmittance of 0.08, and solar transmittance of 0.83.

With solar control film (PS90), the total UV transmittance reduced to 0.02, and solar transmittance decreased to 0.59. The PS90 film added to the visor reduces visible transmittance by 0.11, without compromising a clear vision, and reduces near-infrared transmission by 0.45, therefore almost halving the solar heat gains in the non-visible portion of the solar spectrum. Further, the clear film displays low solar absorbance and, therefore, limits surface overheating. When these combinations were tested outdoors (clear sky conditions 28.4°C, solar radiation of 365 W/m2 and UV radiation of 13 W/m2), the addition of PS90 film on top of the was 2.9 °C cooler than the plane visor 0.6 m/s, solar radiation of 365 W/m2 and UV radiation of 13 W/m2.

Conclusion: XP patients do not have easy access to protective garments with are both UV safe and thermally safe, particularly in warm climates. Addition of a readily available solar film to the UV visor halved solar heat gains.

Vuong-Brender Thanh^1,2 and Schumacher Björn^1,2

¹Institute for Genome Stability in Aging and Disease, Medical Faculty, University and University Hospital of Cologne, Cologne, Germany.

²Excellence Cluster for Cellular Stress Responses in Aging-Associated Diseases (CECAD), Center for Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany.

Thanks to a simple body architecture, the nematode C. elegans can be used to study DNA damage response both at cellular and organismal levels. We used C. elegans xpc-1 mutants, ortholog of the mammalian sensor of DNA damage XPC, to understand alternative repair in mutants defective for the Global Genome Nucleotide Excision Repair (GG-NER) pathway. XPC-1 is strongly expressed in the germline of C. elegans. When first instant larvae of xpc-1 mutants are UV treated, the primordial germ cells (PGCs) fail to develop a germline during the subsequent larval growth to adulthood. We discovered that mutations in the endonuclease gen-1, ortholog of mammalian resolvase of Holiday junctions GEN1, strongly enhanced the UV-induced germline developmental defects of xpc-1 mutants. This increase in UV-sensitivity requires the catalytic activity of GEN-1 as well as its C-terminal region. Our data shows that GEN-1 meditates germ cell arrest in xpc-1 mutants in response to UV, suggesting GEN-1 regulates DNA damage checkpoint in PGCs when the lesions are not repair by the canonical GG-NER pathway. The arrest seems to allow an alternative repair pathway independent of the double strand break repair mediated by brc-1/BRCA1 and brd-1/BARD1, and the Fanconi Anaemia pathway mediated by fcd-2/FANCD2. The absence of GEN-1 – dependent alternative repair results in replication and chromosomal segregation defects during subsequent S-phase and mitosis respectively, that can be rescued partially by activating the spindle assembly checkpoint. Our results point to a potentially important regulator of DNA repair in XP patients.

Teodora Svilenska¹, Chiara Cimmaruta², Claudia Bogner³, Vincent Laugel⁴, Wolfram Gronwald³, Miria Ricchetti², York Kamenisch¹* and Mark Berneburg¹*

¹Department of Dermatology, University Hospital Regensburg, 93042 Regensburg, Germany, Tel.: 0941 944-9601,

²U5 Molecular Mechanisms of Pathological and Physiological Ageing, Institut Pasteur, 25, rue du Dr. Roux, 75724 Paris Cedex 15, France

³Institute of Functional Genomics, Department Functional Genomics, Am BioPark 9, 93053 Regensburg, Germany, Tel.: 0941 943 5015

⁴University Hospital of Strasbourg, Neuromuscular Centre at Hautepierre Hospital, Hautepierre Hospital, Avenue Molière, 67000 Strasbourg, France

*: corresponding authors

email: [email protected], [email protected]

Cockayne syndrome (CS), a rare genetic disease with progeroid symptoms, like, progressive severe neurological defects and UV sensitivity, has no treatment up to now. The investigation of metabolic changes, which are associated with aging processes or stressors, is necessary to increase the knowledge of the complex processes leading to aging of cells and organisms.

It was shown in previous work, that exposure of human skin cells to stressors like UVA irradiation or reactive oxygen species (ROS) leads to significant changes in the cell metabolism, especially in the glucose metabolism. The high levels of UVA induced consumption of glucose and pyruvate could be involved in the ROS detoxification strategies of these UVA exposed cells. In addition to this it is known that CS cells can exhibit higher levels of cellular ROS damage than WT cells.

In this project, we investigated the impact of stressors (ROS) on the metabolism and oxygen consumption in primary human skin fibroblasts derived from CS patients with the premature aging syndrome or from healthy individuals (WT). These cells were treated with repetitive low dose UVA irradiation (inducing ROS) with subsequent measurement of cellular oxygen consumption using a Clark type electrode and metabolic changes in the supernatant of the cells, using nuclear magnetic resonance spectroscopy (NMR).

UVA irradiation induced significant changes in many metabolites (glucose, lactate, pyruvate, acetate, glutamine, glutamate, choline, alanine, betaine) in the cellular supernatant. Similar to WT cells, CS cells showed higher glucose and pyruvate consumption, as well as higher lactate and alanine secretion upon UVA treatment. Interestingly, metabolic differences between WT and CS cells are already present without external stressors (UVA irradiation) and many of these differences increase upon UVA treatment. Concerning cellular respiration, differences in the oxygen consumption rate, between CS and WT cells were visible without external stressors. WT cells show a higher oxygen consumption rate than CS cells. The application of stressors (UVA irradiation) enhanced these differences between WT cells and CS cells.

This study revealed differences in metabolism and respiration between CS cells of patients with premature aging symptoms and WT cells. It is known, that, under specific conditions, processes of cellular respiration can generate high levels of ROS. Therefore, it can be speculated, that CS cells try to exploit metabolic ROS detoxification strategies associated to glycolysis (higher glucose and pyruvate consumption than WT cells) in order to reduce ROS production during respiration (lower respiration rate than WT cells).

Introduction: Cutaneous malignancies are the leading cause of premature mortality among patients with Xeroderma Pigmentosum. Cutaneous Squamous Cell Carcinoma (cSCC) is the most prevalent skin cancer seen among XP patients in our setting. Rapid local and distant metastases due to their impaired DNA function make it difficult to treat with surgery. Cemiplimab has been approved for treating locally advanced and metastatic cSCC. It is however not available in developing countries like Tanzania.

Case Presentation: A 9 year old male presented to us in January 2023 with two large ulcerated tumours on the scalp (temporal region), a fungating mass on the left mandibular region. Prior to attending our facility he had multiple excisions done at peripheral hospitals but the tumours always recurred. He had also received 4 cycles of chemotherapy at the national hospital. Multidisciplinary team effort with ENT and general surgeons was crucial from the beginning of treatment. Biopsies from the national hospital revealed SCC on both scalp tumours invading bone, CT scan of the mandibular tumour revealed SCC with invasion of the parotid gland, pushing the left external auditory meatus and causing severe pain. Paracetamol and ibuprofen did not relief the pain and we requested to start him on morphine. He had anaemia of 7g/dl since the parotid mass bled profusely during wound dressing and was transfused with 3 units of blood. ENT and general surgeons did debulking surgery; underlying muscles were infiltrated with the mass hence complete excision was not possible. A week later the scalp tumours were excised and he was planned for palliative care on discharge. In September 2023 he came for follow up with recurrent tumours on the same sites and even bigger than previously. After several discussions in the tumour board and after asking for donations, we were able to acquire the monoclonal antibody Cemiplimab. He was started on cycles of Cemiplimab to be given after every 2 weeks and he has received 21 cycles. Significant shrinkage of the tumour was noted from cycle 15 where he only had shallow ulcerations on the scalp. There is no new or recurrent cancer growth seen and all the wounds have closed up.

Conclusion: This case is an example of the hurdles, unsuccessful as they may be, that had to be undertaken to treat advanced cSCC in XP due to lack of availability of novel treatments like Cemiplimab which through research has proven to be successful in treating aggressive cSCC. XP patients are perfect candidates for treatment with immunotherapy and this should be available in all settings.

Andrey A. Yurchenko

INSERM U981, Gustave Roussy Cancer Campus, Université Paris Saclay, Villejuif, France

[email protected]

Fatemeh Rajabi

INSERM U981, Gustave Roussy Cancer Campus, Université Paris Saclay, Villejuif, France

[email protected]

Tirzah B. P. Lajus

Departamento de Biologia Celular e Genética, Universidade Federal do Rio Grande do Norte, Av. Senador Salgado Filho, s/n, Natal, 59078–970, Brazil

[email protected]

Hiva Fassihi

National Xeroderma Pigmentosum Service, Department of Photodermatology, St John's Institute of Dermatology, Guy's and St Thomas’ Foundation Trust, London SE1 7EH, United Kingdom

[email protected]

Chikako Nishigori

Division of Dermatology, Department of Internal Related, Kobe University Graduate School of Medicine, Kobe, Japan

[email protected]

Carlos F. M. Menck

Department of Microbiology, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, SP, Brazil

[email protected]

Alain Sarasin

CNRS UMR9019 Genome Integrity and Cancers, Institut Gustave Roussy, Villejuif, France

[email protected]

Sergey Nikolaev

INSERM U981, Gustave Roussy Cancer Campus, Université Paris Saclay, Villejuif, France

[email protected]

Xeroderma Pigmentosum (XP) is characterized by a 1000-fold increased risk of skin cancer due to deficiencies in the NER or TLS pathways. The genomic mechanisms of somatic mutagenesis responsible for this increase are not yet fully understood.

We sequenced genomes from a unique collection of skin tumors (n = 38) originating from cancer-prone XP subgroups (XP-A/C/D/E/V) and developed in vitro models (XP-C/V) to elucidate the mechanisms of UV-induced mutagenesis in XP using detailed bioinformatic analyses.

The ultra-mutated tumor phenotype was observed in skin tumors with impaired GG-NER (XP-E = 350 mut/MB, XP-C = 162 mut/MB) and translesion synthesis (XP-V = 248 mut/MB). Mutational profiles of XP skin tumors with NER defects were dominated by C>T mutations, with each group exhibiting specific trinucleotide context features. XP-C and XP-D tumors showed a notably large percentage of CC>TT double-base substitutions (17–20%) compared to sporadic skin cancers (4.7%). Mutations in XP-A and XP-D tumors, with impaired GG-NER and TC-NER, exhibited a uniform distribution along chromatin genomic compartments, implying that NER activity is a major modulator of genome-wide mutation rate heterogeneity.

XP-V skin tumors with dysfunctional TLS polymerase eta were characterized by a specific mutational profile, including an excess of TG>TT substitutions (28%) absent in sporadic skin cancers. These mutations likely result from error-prone bypass of rare, atypical photolesions in TpA and TpG contexts in the absence of polymerase eta. The mutational signature of canonical UV-induced C>T mutations in pyrimidine dimers was distinct in XP-V tumors, primarily defined by incorrect nucleotide insertion at the 3’ end of photodimers (40-fold higher compared to sporadic cancers). This pattern likely reflects error-prone insertion and error-free extension steps performed by different TLS polymerases.

WGS analysis of clones from UV-irradiated XPC-KO and POLH-KO cell lines revealed 3-fold and 11-fold increased mutagenesis rates, respectively, compared to wild-type cells. These findings demonstrate that error-free TLS bypass plays a major, if not greater, role in reducing UV-induced mutations alongside NER. Genomic analysis of cell lines transfected with photolesion-specific photolyases highlighted the primary role of CPD in mutation generation and 6-4PP in the DNA damage response.

The accumulation of unrepaired DNA lesions on the untranscribed strand, nonspecific TLS activity, and the inability to bypass atypical photolesions error-free collectively explain the increased incidence of skin cancer in XP patients.

Genetic analyses of large cohorts of cancer patients have revealed a correlation between somatic mutations in DNA repair pathway genes and the responsiveness of patients to DNA-damaging chemotherapeutics and immune checkpoint inhibition. In line with this, several case studies have shown that Xeroderma Pigmentosum (XP) patients with melanoma respond well to anti-PD1 therapy, suggesting that XP melanomas enable an immune-favoured tumor environment. To examine nucleotide excision repair (NER) deficient melanomas in vivo, we focused on the helicase ERCC2/XPD and developed a melanoma mouse model with ERCC2 wildtype (wt) or ERCC2-mutant tumors that harboured the deleterious point mutations K48R or D234N, the latter occurring in XP patients. For this purpose, we engineered murine melanoma cells that were first characterized in vitro and then transferred to C57BL/6J mice. As expected, XPD-mutant cells displayed increased sensitivity to UV irradiation and cisplatin treatment in cell culture. In vivo, XPD-K48R melanomas developed only in a minority of cases. XPD-D234N tumors developed earlier than XPD-wt tumors, consistent with the observed increased proliferation rate of XPD-D234N cells under basal conditions. Despite their rapid onset, 50% of XPD-D234N melanomas underwent spontaneous regression within 2–3 weeks, a phenomenon never observed in XPD-wt tumors. When mice bearing XPD-D234N melanomas were treated with a combination of cisplatin and PD-1 blocking antibody, almost all tumors regressed, while no therapy response was observed for mice with XPD-wt melanomas. These findings suggest that XPD-mutant melanomas are more easily resolved by the immune system of the host, particularly under conditions of NER-associated DNA damage and immune therapy. Future research will focus on the molecular mechanisms underlying this enhanced therapeutic responsiveness, paving the way for potential clinical applications targeting XPD in cancer.

Tycho E.T. Mevissen^1,2, Maximilian Kümmecke³, Ernst W. Schmid¹, Lucas Farnung³, and Johannes C. Walter^1,2

¹Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA

²Howard Hughes Medical Institute

³Department of Cell Biology, Harvard Medical School, Boston, MA

In transcription-coupled DNA repair, RNA polymerase II stalling at DNA lesions leads to the efficient activation of nucleotide excision repair (TC-NER). This pathway was discovered almost 40 years ago, yet fundamental questions about its mechanism remain unanswered, in large part due to the lack of a cell-free system that supports this pathway. We have recapitulated vertebrate cell-free TC-NER, and we use this system to study STK19, a candidate TC-NER factor known to promote transcription recovery after cellular exposure to UV light. When a plasmid containing a site-specific cisplatin DNA intrastrand crosslink is transcribed in frog egg extracts, error-free repair is observed that depends on the canonical repair proteins CSB, CRL4^CSA, UVSSA, ELOF1, as well as STK19. Structural prediction and cryo-electron microscopy indicate that STK19 is an integral component of the TC-NER complex that interacts with CSA-DDB1, the RNA polymerase II subunit RPB1, and the XPD helicase subunit of TFIIH. Mutating these interfaces disrupts cell-free TC-NER, and molecular modeling suggests that STK19 positions TFIIH such that the damaged DNA strand is threaded into the XPD helicase for subsequent lesion verification. In conclusion, our novel cell-free system that supports bona fide eukaryotic TC-NER strongly suggests that STK19 couples RNA polymerase II stalling to TFIIH-dependent downstream nucleotide excision repair events.

Sikandar G. Khan¹, Wenelia Baghoomian¹, Christiane Kuschal¹, Deborah Tamura¹, Maxwell P. Lee¹, John J. DiGiovanna^{1, *}, Rodrigo Cepeda-Valdes², Julio Salas-Alanis³ and Kenneth H. Kraemer¹

¹Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, United States

²Dystrophic Epidermolysis Bullosa Research Association Mexico Foundation, Monterrey, Mexico; ³Instituto Dermatologico de Jalisco, Jalisco, Mexico, *Deceased

Trichothiodystrophy (TTD) is a rare (1 per million) autosomal recessive multisystem developmental disorder characterized by short, brittle hair with transverse “tiger-tailed banding” on polarized microscopy. TTD has been reported to be caused by mutations several different functional groups of genes: nucleotide excision repair (NER)/ basal transcription factor II H (TFIIH) genes: ERCC2/XPD, ERCC3/XPB and GTF2H5/ TTDA; amino acid charging tRNA genes (TARS, MARS1, AARS1, and CARS); basal transcription factor II E (GTF2E2/TFIIEβ); X-linked ring finger protein 113A (RNF113A), and a gene of unknown function (MPLKIP/TTDN1). We performed whole exome sequencing to identify a candidate gene in Sabinas brittle hair syndrome, a mild form of TTD. We report 5 non-photosensitive adult patients from 3 unrelated families with a homozygous missense mutation in DBR1 (p.D262Y) encoding the RNA lariat debranching enzyme DBR1 which catalyzes the removal of introns from pre-mRNA in the nucleus. Post-UV DNA repair was normal, indicating that DBR1 was not involved in NER/TFIIH. The cells had reduced levels of DBR1 mRNA and no detectable DBR1 protein. Previous reports described interaction of DRB1 and TTDN1 proteins. We found markedly reduced levels of TTDN1 protein in cells from patients with DBR1 mutations and no detectable levels of TTDN1 protein in the cells from patients with TTDN1 mutations. The stabilization of either of these proteins is critical for splicing and transcription. Genetic analysis suggests an ancient origin of this mutation. Thus, we identified DBR1 as causing Sabinas brittle hair syndrome supporting the hypothesis that TTD can be caused by transcriptional impairment.

Marc Majora, Rituparna Bhattacharjee, Selina Dangeleit, Andrea Rossi, Jean Krutmann

IUF – Leibniz-Institut für umwelt- medizinische Forschung GmbH, Düsseldorf, Germay

Xeroderma pigmentosum type A (XPA), an inherited disease characterized by UV hypersensitivity, high skin cancer risk and premature aging, is thought to be caused by defective repair of nuclear DNA. Recent studies, however, suggest that XPA proteins might have functions beyond nuclear DNA repair. Here we show – by analyzing purified mitochondrial fractions from primary human dermal fibroblasts (HDF) – that XPA proteins are located inside the mitochondria. In particular, mitochondrial XPA content was increased when HDF were either irradiated with UVB or treated with the pro-oxidant menadione suggesting that XPA might be important for repairing damage inside the mitochondria and protecting their integrity. Accordingly, sequencing of mitochondrial DNA (mtDNA) of HDF obtained from XPA patients (XPA HDF) revealed an elevated load of mutations as compared with healthy HDF, which was further increased by UVB irradiation. These data suggest that XPA is not only involved in the repair of nuclear DNA but also participates in the repair of mtDNA. The pivotal role of XPA in maintaining mitochondrial function was also reflected by a RNA-Seq transcriptome analysis showing that “Mitochondrial Gene Expression” and “Mitochondrial Translation” were among the most severely suppressed biological processes in UVB-irradiated XPA HDF. To assess potential consequences for mitochondrial function, we next measured the cellular ATP production rate. We found that unirradiated XPA HDF had a higher total ATP production rate than healthy HDF, which was due to increased mitochondrial but not glycolytic ATP production rate. If cells were stressed by UVB irradiation, mitochondrial ATP production rate in XPA HDF was reduced by more than 50% while it remained stable in normal HDF. Thus, XPA HDF have an increased ATP demand, which in unstressed cells can still be met by their mitochondrial function. Upon irradiation, however, compensation fails and XPA HDF become energy deficient. As the chaperone HSP90 serves as an ATP sensor which stabilizes proteins in an ATP-dependent manner, we next analyzed the abundance of HSP90 client proteins. HSP90 levels remained constant, but a marked loss of ErbB2, EGFR, STAT3 and SIRT1 was detected in irradiated XPA HDF when compared to healthy HDF, reflecting collapse of proteostasis. Our results indicate that XPA proteins are present in mitochondria where they maintain integrity of mtDNA and mitochondrial function to ensure cellular ATP supply and thereby prevent collapse of proteostasis, a well-known driver of aging.

Paola Giunti, Hector Garcia-Moreno, Douglas R Langbehn, Adesoji Abiona, Isabel Garrood, Zofia Fleszar, Marta Antonia Manes, Ana M Susana Morley, Emma Craythorne, Shehla Mohammed, Tanya Henshaw, Sally Turner, Harsha Naik, Istvan Bodi, Robert P E Sarkany, Hiva Fassihi, Alan R Lehmann

National Xeroderma Pigmentosum Service, Department of Photodermatology, St John's Institute of Dermatology, Guy's and St Thomas' Foundation Trust, London SE1 7EH, United Kingdom

and

Genome Damage and Stability Centre, University of Sussex, Falmer, Brighton BN1 9RQ, United Kingdom

Xeroderma pigmentosum (XP) results from biallelic mutations in any of eight genes involved in DNA repair systems, thus defining eight different genotypes (XPA, XPB, XPC, XPD, XPE, XPF, XPG and XP variant or XPV). In addition to cutaneous and ophthalmological features, some patients present with XP neurological disease. It is unknown whether the different neurological signs and their progression differ among groups. Therefore, we aim to characterize the XP neurological disease and its evolution in the heterogeneous UK XP cohort.

Patients with XP were followed in the UK National XP Service, from 2009 to 2021. Age of onset for different events was recorded. Cerebellar ataxia and additional neurological signs and symptoms were rated with the Scale for the Assessment and Rating of Ataxia (SARA), the Inventory of Non-Ataxia Signs (INAS) and the Activities of Daily Living questionnaire (ADL). Patients’ mutations received scores based on their predicted effects. Data from available ancillary tests were collected.

Ninety-three XP patients were recruited. Thirty-six (38.7%) reported neurological symptoms, especially in the XPA, XPD and XPG groups, with early-onset and late-onset forms, and typically appearing after cutaneous and ophthalmological symptoms. XPA, XPD and XPG patients showed higher SARA scores compared to XPC, XPE and XPV. SARA total scores significantly increased over time in XPD (0.91 points/year, 95% confidence interval: 0.61, 1.21) and XPA (0.63 points/year, 95% confidence interval: 0.38, 0.89). Hyporeflexia, hypopallesthaesia, upper motor neuron signs, chorea, dystonia, oculomotor signs and cognitive impairment were frequent findings in XPA, XPD and XPG. Cerebellar and global brain atrophy, axonal sensory and sensorimotor neuropathies, and sensorineural hearing loss were common findings in patients. Some XPC, XPE and XPV cases presented with abnormalities on examination and/or ancillary tests, suggesting underlying neurological involvement. More severe mutations were associated with a faster progression in SARA total score in XPA (0.40 points/year per 1-unit increase in severity score) and XPD (0.60 points/year per 1-unit increase), and in ADL total score in XPA (0.35 points/year per 1-unit increase).

Symptomatic and asymptomatic forms of neurological disease are frequent in XP patients, and neurological symptoms can be an important cause of disability. Typically, the neurological disease will be preceded by cutaneous and ophthalmological features, and these should be actively searched in patients with idiopathic late-onset neurological syndromes. Scales assessing cerebellar function, especially walking and speech, and disability can show progression in some of the groups. Mutation severity can be used as a prognostic biomarker for stratification purposes in clinical trials.

Mark Berneburg

Department of Dermatology, University Hospital Regensburg, Germany

The human genome is constantly exposed to various sources of DNA damage. Ineffective protection from this damage leads to genetic instability, which can ultimately give rise to somatic disease, premature aging and cancer. Therefore, our organism commands a number of highly conserved and effective mechanisms responsible for DNA repair. If these repair mechanisms are defective due to germline mutations in relevant genes, rare diseases with DNA repair deficiencies can arise. Today, a limited number of rare hereditary diseases characterized by genetic defects of DNA repair mechanisms is known, comprising ataxia telangiectasia, Nijmegen breakage syndrome, Werner syndrome, Bloom Syndrome, Fanconi anemia, Cockayne syndrome Trichothiodystrophy as well as Xeroderma pigmentosum. Although heterogeneous in respect to selected symptoms, these rare disorders share many clinical features such as growth retardation, neurological disorders, premature aging, skin alterations including abnormal pigmentation, telangectasia, xerosis cutis, pathological wound healing as well as an increased risk of developing different types of cancer. Better understanding of underlying molecular pathology in these diseases, has given rise to potential treatment approaches. In this talk, the different routes and modes of action for therapeutic approaches – ranging from treatments of underlying mechanisms to treatments of the different segmental clinical symptoms of these patients – will be discussed.

Nihan Erden¹, Björn Schumacher¹

¹Institute for Genome Stability in Ageing and Disease, Cologne Excellence Cluster for Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne

DNA damage is a causal factor of both cancer development and the aging process. The tumor suppressor p53 is a central mediator of the DNA damage response (DDR) and the single most frequently mutated gene in human cancer. Many studies showed that cell-cycle and apoptosis functions of p53 are important for preventing tumor development and the activation of p53 was regulated cell-autonomously depending on the type and severity of the DNA damage. It was recently discovered that the p53-mediated DDR in stem cells is not regulated only cell-autonomously but also regulated through signalling via the niche cells. The translation initiation factor IFE-4 in C. elegans is activated in somatic gonad precursor niche cells that surround the primordial germ cells, when the latter carry DNA damage. Moreover, it was demonstrated that the IFE-4 ortholog eIF4E2 in mammals is induced in niche cells upon UV-induced DNA damage and is required for the induction of p53 in hair follicle stem cells (HFSCs). These data thus indicate a highly conserved mechanism of non-cell-autonomous regulation of the p53-mediated DDR in stem cells.

We are currently employing in vivo and ex vivo experimental systems with eIF4E2 epidermis specific knockout mice to dissect the mechanisms of the interactions between niche and stem cells, and to understand the role of eIF4E2 in skin homeostasis and carcinogenesis. To further assess the clinical relevance of the eIF4E2 function, we will characterize eIF4E2 in human squamous cell carcinoma.

Dr Hiva Fassihi

National Xeroderma Pigmentosum Service, Department of Photodermatology, St John's Institute of Dermatology, Guy's and St Thomas’ Foundation Trust, London SE1 7EH, UK

Prof Alan Lehmann

Genome Damage and Stability Centre, University of Sussex, Falmer, Brighton BN1 9RQ, UK

Over 100 patients with Xeroderma Pigmentosum (XP), over 30 with Cockayne Syndrome (CS), and 13 with Trichothiodystrophy (TTD) are under long-term follow-up in the UK National Nucleotide Excision Repair (NER) Multidisciplinary Service. Involvement of the UK patient support groups, Action for XP and Amy and Friends, is essential in the care of these patients.

The aims of the specialist team of clinicians, nurses and scientists is to improve clinical outcomes and reduce morbidity and mortality. Over the last 14 years, life expectancy of patients with XP in the UK has significantly improved when compared to data on 106 patients from a National Institutes of Health study analysing the worldwide literature from 1971 to 2009. In the UK, XP patients without neurodegeneration now have a life expectancy comparable to the general UK population, because of early diagnosis, meticulous photoprotection and prompt diagnosis and treatment of any skin and ocular cancers.

Functional studies and molecular analysis to determine the pathogenic variants in the NER genes (part of the specialist service) have enabled the detailed genotype-phenotype examination of these patients. The careful clinical assessment of suspected cases has led to the discovery of a new XP complementation group, XP-J, with mutations in the GTF2H4 gene, and contributed to the reporting of MORC2-related disorder with phenotypic similarities to CS.

Among the patients visiting the multidisciplinary clinic, several groups have relatively mild phenotypes. In most of these cases, in XP-A, D and G, they are associated with mutations at splice donor sites (outside the invariant GT nucleotides), causing abnormal splicing of most of the mRNA, but a residual amount of normally spliced mRNA. The resulting small amount of normal protein is sufficient to ameliorate or delay the onset of the clinical features. In four CS patients, mutation of the G at the fifth base of a splice donor site results in a markedly delayed onset of the clinical features.

Marvin van Toorn, Jurgen Marteijn

Department of Molecular Genetics and Oncode Institute, Erasmus University Medical Centre, Rotterdam, the Netherlands

Nucleotide excision repair (NER) preserves genome stability through a ‘cut-and-patch’-type DNA repair reaction. Whereas the initial NER reaction steps that sequentially recognize, verify and excise helix-distorting DNA lesions through dual incision are well-characterized, mechanistic insight how the generated ssDNA gap is subsequently restored remains limited. Here, we study the mechanisms and factors involved in this late, post-incision NER step. We show that RFC mediates PCNA recruitment and loading at NER-generated ssDNA gaps, after which POLD3 displaces RFC to recruit POLD1 and enable polδ-dependent repair synthesis. Subsequent LIG3-mediated nick ligation promotes PCNA unloading by ATAD5-RLC, which facilitates PCNA recycling to newly NER-generated ssDNA gaps. Interestingly, we found that PCNA and polδ recruitment to sites of DNA damage was severely reduced in actively replicating cells. This could explain the existence of a parallel, non-redundant and PCNA-independent gap restoration pathway involving the alternative clamp loader CTF18-RLC, polε and LIG1. Collectively, our study provides important insights into the intricate mechanisms that preserve genomic integrity by coordinating the productive restoration of NER-generated ssDNA gaps throughout the cell cycle.

Chikako Nishigori¹, Mariko Tsujimoto¹ and Shinichi Moriwaki²

¹Division of Dermatology, Department of Internal Related, Graduate School of Medicine, Kobe University, Kobe, Japan

² Department of Dermatology, Osaka Medical and Pharmaceutical University

Xeroderma pigmentosum (XP) is an autosomal recessive DNA repair disorder characterized by photosensitivity and progressive central and peripheral nervous system impairment. Currently, there are no effective treatments for XP aside from avoiding UV exposure. It has been shown that XP cells are impaired in scavenging ROS and oxidative DNA damage. Therefore, several antioxidants were examined for reducing cytotoxicity caused by oxidative stress in XP-A cells. Since in vitro experiments showed N-acetyl-5-methoxytryptamine and nicotinamide reduced cytotoxicity of XP-A cells caused by radical inducers, we conducted an in vivo experiment to investigate the therapeutic potential of N-acetyl-5-methoxytryptamine. Treatment with N-acetyl-5-methoxytryptamine mitigated UV-induced inflammation, skin tumorigenesis and hearing deterioration in XP model mice. Our results show that N-acetyl-5-methoxy-tryptamine could alleviate XP symptoms through its anti-inflammatory and antioxidant properties. <https://www.sciencedirect.com/science/article/pii/S0923181125000039>.

Therefore, we conducted a clinical trial on the efficacy of N-acetyl-5-methoxytryptamine (NPC-15) for patients with XP with exaggerated sunburn-reaction type by a multicenter, double-blinded placebo-controlled, two-group crossover study followed by a 52-weeks open study. Ethics approval was overseen by the Kobe University Institutional Review Board and Osaka Medical and Pharmaceutical University Institutional Review Board, and the study was conducted in accordance with the approved protocol (Japan Registry of Clinical Trials (jRCT) identifier: jRCTs051210181. Registered on February 23, 2022. The clinical trial was conducted from April 2022 to December 2023. Twenty patients (Age; 10.6±6.8, F/M; 12/8). Eighteen patients were XP-A. After key open, all data was analyzed and statistically investigated. In the primary endpoint, the MED, 72 hours (+/-6 hours) after UV irradiation on the 15th day (crossover period I and crossover period II) of investigational drug administration, the treatment effect in NPC-15 administration did not show a statistically significant improvement compared to placebo administration. From the viewpoint of individual patients, data suggesting a usefulness on some of the items including neurological severity scale score on XP were obtained. NPC-15 had no significant safety problem. Brief summary is available through the URL below. <https://jrct.niph.go.jp/latest-detail/jRCT2051210181>.

Melanie van der Woude, Karen L. Thijssen, Mariangela Sabatella, Jurgen A. Marteijn, Wim Vermeulen, Hannes Lans

Department of Molecular Genetics, Erasmus MC, Rotterdam, Netherlands

The versatile nucleotide excision repair (NER) pathway protects organisms against the harmful effects of various types of helix-distorting DNA damage. Hereditary NER deficiency gives rise to several human cancer-prone and/or progeroid disorders, including xeroderma pigmentosum, Cockayne syndrome, trichothiodystrophy, or a combination of these. It is not exactly understood how defects in the same DNA repair pathway cause different disease features and severity.

To better understand the pathogenesis underlying different NER disorders, we make use of human cellular and C. elegans model systems to investigate mechanisms of DNA repair and their in vivo impact. We previously reported that the core NER machinery is continuously targeted to DNA damage in human cells carrying severe NER disease mutations. Here we show, using real-time imaging, that different types of NER deficiency differently affect the binding of core NER factors to DNA damage and that the prolonged binding of specific NER factors to DNA damage correlates to NER disease severity. Using C. elegans, we show that DNA damage can cause a strong developmental arrest and neuronal dysfunction, which is dependent on transcription-coupled DNA repair and on the persistence of specific DNA repair intermediates in the absence of repair. Together, these results identify stalled transcription-coupled NER intermediates as a pathogenic feature of NER deficiency and show that these adversely affect tissue functionality and organismal development.

Vilhelm A Bohr

University of Copenhagen, Center for Healthy Aging, and previously National Institute on Aging, NIH

We find that some DNA repair defective diseases with severe neurodegeneration have mitochondrial dysfunction. Our studies involve cell lines, the worm (c.elegans), and mouse models and include the premature aging syndromes Xeroderma pigmentosum group A, Cockaynes syndrome, Ataxia telangiectasia and Werner syndrome. It also includes models of Alzheimers Disease (AD). Under these conditions we find a pattern of hyperparylation, deficiency in NAD⁺ and Sirtuin signaling and mitochondrial stress, including deficient mitophagy as a prominent feature. NAD supplementation stimulates mitochondrial functions including mitophagy and stimulates DNA repair pathways. Cockayne syndrome (CS) mice have a hearing deficit that reflects the one seen in the patients. Short term NAD supplementation with NR deminishes the hearing loss. The hearing loss is a of a similar type seen in age related hearing loss. Treatment of mice with NR improves the age related hearing loss. Current studies in CS mice show kidney disease reflecting what is also seen in many CS patients and the mice have deficits in NAD synthesis pathways.

Clinical trials with NAD intervention have shown benefits in AT patients and a current intervention study in Werner patients also shows some benefits. These will be discussed.

Giulia Branca^a, Debora Ferri^a, Manuela Lanzafame^a, Erica Gandolfi^a, Gianluca Guida^a, Tiziana Nardo^a, E. Botta^a and Donata Orioli^a

^aIstitute of Molecular Genetics (IGM) L.L. Cavalli Sforza, CNR, 27100 Pavia, Italy

The multiprotein complex TFIIH is a key factor in transcription and nucleotide excision repair (NER) pathway. TFIIH malfunctioning results in distinct autosomal recessive disorders, including the cancer-prone xeroderma pigmentosum (XP) and the multisystemic trichothiodystrophy (TTD), the latter one being characterized by physical and mental retardation, signs of premature ageing, but no skin cancer. Both XP and TTD cells are characterized by hypersensitivity to UV irradiation, persistence of NER proteins at the site of damage and accumulation of unrepaired DNA lesions. We have shown that TTD more than XP cells suffer of wide transcription deregulations. Whether this is accountable to TFIIH malfunctioning caused by TTD-specific mutations or to the findings that all TTD-causing mutations affect the stability of the entire complex and result in reduced TFIIH amount, is still an open question. The finding that TFIIH stabilization by low temperature or chemical treatment partially recover TFIIH functionality in primary cells from thermo-sensitive TTD cases (whose clinical features worsen with fever episodes), suggested to us the relevance of preserving TFIIH amount in human cells. We have now identified a novel TFIIH-containing multiprotein assembly bound to the chromatin, whose function is to assists RNA polymerase II during transcription. Reduced levels of wild-type TFIIH or other components of the protein assembly lead to transcription alterations similar to those observed in TTD. Overall, our findings demonstrate that quantitative, as well as qualitative, TFIIH alterations contribute to the wide spectrum of TTD clinical features.

Kenneth H. Kraemer¹, Deborah Tamura², Sikandar G. Khan, John J. DiGiovanna³

¹Lab of Cancer Biology and Genetics, NCI, NIH, Bethesda, MD, USA emeritus

²retired

³deceased

Studies of xeroderma pigmentosum (XP) began at NIH in 1971 to gain insights into clinical disease and mechanisms of DNA damage and repair. Detailed clinical and lab exams of skin and eye abnormalities, neurologic degeneration, hearing loss, skin and internal cancers, and aging were performed. We collaborated within NIH and with extra-mural scientists. Findings included discovery of 5 excision repair (ER) deficient XP complementation groups, the ER proficient XP variant, and measuring the > 1,000-fold increase in skin and eye cancer. We developed host cell reactivation assays for UV survival and mutagenesis and found that one DNA dimer inactivated expression in XPA cells. XP patients treated with oral retinoids provided the first demonstration of effective cancer chemoprevention in humans. Audiograms were used to assess the rate of XP neurological degeneration. Autopsies revealed infantile brains in adult XP patients attesting to the massive atrophy caused by XP. Internal cancers include brain and spinal cord neoplasms, thyroid cancer, leukemia, lymphoma and lung cancer (in smokers). Premature menopause, a feature of aging, was observed (median age 29.5 years was > 20 years younger than in the U.S. population). We found XPA patients with severe, intermediate, or mild disease. Trichothiodystrophy (TTD) patients with mutations in the XPD gene had abnormal development including absent myelin in their brain, multiple infections, bone abnormalities, aseptic necrosis of the hips and premature death but no increase in skin cancer. Mothers of TTD children with XPD mutations had many pregnancy abnormalities while mothers of XP children with XPD mutations had normal pregnancies thereby linking XPD function with human fetal development. We found two new RNA related TTD causing genes: TFIIE2 and DBR1. With Dr V. Bohr in 1985 we established the DNA Repair Interest Group with monthly videoconferences (several hundred archived at http://videocast.nih.gov) and initiated the first 3 of this series of international XP meetings (in 2004, 2006, and 2010). These intensive investigations of XP at NIH and worldwide have resulted in advances in understanding disease mechanisms and, most importantly, in increasing patient wellbeing and prolonging their life expectancy.

Dr. R. Sarkany

Consultant Dermatologist, UK XP National Service, London

The most common cause of premature death in XP is metastatic skin cancer (1) and 80% of skin cancers of XP are on the face, head and neck (2). So rigorous and absolute photoprotection from ultraviolet is crucial in the management of patients with XP, particularly of the face.

We have recently used a new methodology to accurately estimate the daily dose of UV reaching the skin of the face over a prolonged period, and used this to study photoprotection behaviour in detail over a 3 week period in 36 XP patients in the UK. We found a wide range of UV protection (i.e. of daily UV dose to the face), with around 35% of adult XP patients protecting significantly more poorly than the rest (3). We went on to demonstrate that poor photoprotection correlated closely with 9 variables, 7 of which were potentially reversible psychological factors (4).

We went on to design a personalised behaviour change intervention (‘XPAND’) to target these psychological factors shown to correlate with poor photoprotection (i.e. high daily UV dose to the face). It involves 7 one-to-one sessions delivered by a nurse or a psychologist.

In this lecture I present the results of our randomised controlled trial of this intervention in 16 XP patients with poor photoprotection. The design was a two-arm parallel group randomised control trial with a delayed intervention control arm who received XPAND the following year. The primary endpoint was the mean daily UV dose to the face during a 3 week period in June or July following XPAND (or no intervention in the control group).

Of 16 patients randomised, 13 provided sufficient data for primary outcome analysis. The XPAND group (n = 8) had a lower mean daily UV dose to the face than the control group (p<0.001). The delayed intervention control group also had a lower mean daily dose to the face after the intervention than before, but not at a statistically significant level. Secondary endpoints were also analysed. Health economic analysis was also carried out and predicted that XPAND was a cost-effective treatment, by reducing long term treatment costs associated with UV exposure.

In this talk I will discuss these data, what can and what cannot be concluded from this small randomised controlled trial, and the implications for clinical management of XP.

Alain Sarasin¹, Andrey A. Yurchenko² and Sergey Nikolaev²

¹UMR9019 CNRS, Gustave Roussy and Paris-Saclay University, Villejuif, France

²INSERM U981, Gustave Roussy and Paris-Saclay University, Villejuif, France

Xeroderma pigmentosum (XP) is a rare, autosomal, recessive genodermatosis caused by Excision Nucleotide Repair (NER) deficiency. These patients are extremely sensitive to sunlight leading to an increased frequency of skin cancers on exposed body sites. Due to constant photoprotection and better therapeutic education, XP patients live longer than in the past. Recently, it was found that some XP patients are at a very high risk of developing internal tumors, including central nervous systems, hematological malignancies, gynecological and thyroid cancers (Nikolaev et al., Orphanet J. Rare Dis., 2022, 17, 104).

We analyzed four published, international, clinically well-defined XP cohorts (from the States, France, England and Brazil) and calculated the cancer risk of these patients. The Odds Ratio (OR) are very high for young XPs (more than a thousand times higher than for the general population) for the 0-20-year-old French XPs. Very high OR are also observed for English, French, and American XPs for developing brain tumors, hematological malignancies, and thyroid tumors. Among XP patients, the most susceptible to developing internal tumors are the patients from the XP-C group, particularly those who bear the founder XPC mutation from North Africa (Sarasin et al., Blood, 2019, 133,2718; Sarasin, Cancers, 2023, 15, 2706).

We analyzed, by whole genome sequencing, 22 internal tumors from XP patients, mainly hematological malignancies, gynecological and thyroid tumors. Results demonstrated a dramatic increase in mutation rates in XP-C tumors versus sporadic tumors. A strong mutational asymmetry with respect to transcription and level of gene expression demonstrated the existence of transcription-coupled repair in vivo in humans. Mutations appeared to be caused by unrepaired bulky guanine lesions on the untranscribed strands of DNA (Yurchenko et al., Nature Comm., 2020, 11, 5834; Yurchenko et al., Commun Med, 2023, 3, 109). The mutational profiles of internal XP-C tumors are very specific to NER-deficiency and nearly identical between all XP-C internal tumors regardless of the tumor type, and completely different from the tissue-matched sporadic tumors.

Physicians following XP patients should be aware of the high risk of internal tumors. Prevention and early detection of leukemia and brain, gynecological, and thyroid tumors are needed. Screening should be done every year starting around the age of 10–12 years (for example, early anemia occurs several years before MDS/ leukemia in some XP-C patients).

Diana van den Heuvel^1,11, Marta Rodríguez-Martínez^2,11, Paula J. van der Meer^1,11, Nicolas Nieto Moreno³, Jiyoung Park⁴, Hyun-Suk Kim⁴, Janne J.M. van Schie¹, Annelotte P. Wondergem¹, Areetha D'Souza⁴, George Yakoub¹, Anna E. Herlihy², Krushanka Kashyap³, Thierry Boissière^2,3, Jane Walker², Richard Mitter⁶, Katja Apelt¹, Klaas de Lint⁷, Idil Kirdök⁷, Mats Ljungman^8,9, Rob M.F. Wolthuis⁷, Patrick Cramer¹⁰, Orlando D. Schärer^4,5, Goran Kokic^10,12, Jesper Q Svejstrup^2,3,12, Martijn S. Luijsterburg^1,12

¹Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands

²Mechanisms of Transcription Laboratory.

³Department of Cellular and Molecular Medicine, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen, Denmark.

⁴Center for Genomic Integrity, Institute for Basic Science, Ulsan, Republic of Korea

⁵Department of Biological Sciences, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea

⁶Bioinformatics and Biostatistics, The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK.

⁷Department of Clinical Genetics, Section Oncogenetics, Cancer Center Amsterdam, Amsterdam University Medical Center, Amsterdam, the Netherlands

⁸Department of Radiation Oncology, University of Michigan, Ann Arbor, MI, USA

⁹Department of Environmental Health Sciences, Rogel Cancer Center and Center for RNA Biomedicine, University of Michigan, Ann Arbor, MI, USA

¹⁰Max Planck Institute for Multidisciplinary Sciences, Department of Molecular Biology, 37077 Göttingen, Germany.

¹¹ These authors contributed equally

¹² Senior authors

Transcription-coupled DNA repair (TCR) removes bulky DNA lesions impeding RNA polymerase II (RNAPII) transcription. Recent studies have outlined the stepwise assembly of TCR factors CSB, CSA, UVSSA, and TFIIH around lesion-stalled RNAPII. However, the mechanism and factors required for the transition to downstream repair steps, including RNAPII removal to provide repair proteins access to the DNA lesion, remain unclear. Here, we identify STK19 as a TCR factor facilitating this transition. Loss of STK19 does not impact initial TCR complex assembly or RNAPII ubiquitylation but delays lesion-stalled RNAPII clearance, thereby interfering with the downstream repair reaction. Cryo-EM and mutational analysis reveal that STK19 associates with the TCR complex, positioning itself between RNAPII, UVSSA, and CSA. The structural insights and molecular modeling suggest that STK19 positions the ATPase subunits of TFIIH onto DNA in front of RNAPII. Together, these findings provide new insights into the factors and mechanisms required for TCR.

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摘要

Rupesh Paudel1,2*, Lena F Sorger1*, Anita Hufnagel1, Mira Pasemann1, Tamsanqa Hove1,3, andr<s:1> marquard1,4, Susanne Kneitz5, Andreas Schlosser6, Caroline Kisker3, Jochen Kuper3#, Svenja Meierjohann1,4#1德国维尔茨堡大学病理研究所，97080维尔茨堡；2德国维尔茨堡大学附属医院，97080维尔茨堡；3 rudolf Virchow综合与转化生物成像中心，结构生物学研究所；德国维尔纽斯堡大学，97080维尔纽斯堡；4维尔纽斯堡大学美因弗兰肯综合癌症中心，97080维尔纽斯堡；5维尔纽斯堡大学生物化学与细胞生物学系，97074维尔纽斯堡；6维尔纽斯堡大学综合与转化生物成像中心，质谱学部，97080维尔纽斯堡；摘要DNA修复解旋酶XPD的种系突变可引起色素干皮病（XP）、毛癣营养不良症（TTD）和Cockayne综合征。XP患者患包括黑色素瘤在内的皮肤癌的风险增加，即使在年轻时也是如此。尽管存在DNA修复缺陷，但在TTD患者中没有观察到这种情况。为了研究TTD细胞是否具有抑制肿瘤发生的特征，我们建立了包含XPD变体R722W的TTD黑色素瘤细胞模型。有趣的是，TTD黑色素瘤细胞表现出降低的致瘤性特征和增加的黑素细胞谱系分化因子MITF的特征，这与red2 （mTOR/S6K/4EBP1依赖的蛋白质翻译机制的抑制剂）的强烈基础上调有关。REDD2水平部分由MITF驱动，在紫外线照射下增加，并有助于减少黑色素瘤的增殖。为了研究黑素细胞（黑色素瘤的祖细胞类型）是否会影响类似的过程，我们建立了TTD黑素细胞模型。同样，MITF基因标记增加，这一次没有影响REDD2的表达。然而，蛋白质翻译分析显示，在紫外线胁迫后，核糖体蛋白质合成减少，特别是在R722W黑素细胞中，这表明蛋白质翻译机制受损。在TTD XPD变体A725P中也发现了蛋白质翻译受损，但在导致XP的XPD变体D234N中没有发现。总之，尽管R722W的效应物在黑色素瘤细胞和黑素细胞之间存在部分差异，但它们会导致翻译抑制，从而降低适应度，特别是在紫外线照射下。这可能限制了紫外线驱动肿瘤发生的可能性，并解释了为什么TTD患者不会发展为黑色素瘤。Gaia Veniali1, Anita Lombardi1, Massimo Teson2, Tiziana Nardo1, Elena bott1, Elena Dell'Ambra2, Donata Orioli1, Manuela Lanzafame11CNR-Istituto di Genetica Molecolare, Pavia, Italy2Istituto Dermopatico Dell 'Immacolata (IDI), Rome， italy核苷酸切除修复（NER）是人类唯一致力于去除紫外线（UV）辐射诱导的大体积DNA加合物的DNA修复系统。NER缺陷是遗传性色素干皮病（XP）的原因，该疾病的特点是由于紫外线诱导的未修复DNA损伤的积累，导致黑色素瘤和非黑色素瘤皮肤癌的高易感性。有趣的是，内质网相关基因XPB或XPD的突变也可导致毛硫营养不良（TTD），这是另一种罕见的以内质网缺陷为特征的疾病。然而，与XP不同的是，TTD患者不会发展为癌症，但其特征是毛发异常、产前或产后生长衰竭、神经发育和神经功能障碍、早衰迹象。对携带同一基因突变的XP和TTD患者皮肤细胞的调查和比较基因表达谱研究，为识别驱动或抵消皮肤癌发生的分子途径提供了一个有前途的工具。我们收集的xpd突变患者的原代皮肤成纤维细胞和角化细胞进行了全转录组分析。我们发现了疾病特异性表达特征，XP细胞表现出肿瘤样特征，其特征是参与炎症和细胞外基质重塑的基因上调，而TTD细胞表现出抗肿瘤特征，其特征是肿瘤抑制基因上调和致癌途径下调。目前正在通过沉默或过表达对照皮肤细胞中感兴趣的基因，并利用三维（3D）培养模型来模拟实体癌的关键方面，包括生长、缺氧和侵袭性的机械调节，来研究已确定的转录失调与皮肤癌病理生理的相关性。 Cemiplimab已被批准用于治疗局部晚期和转移性cSCC。然而，在坦桑尼亚等发展中国家却没有。病例介绍：一名9岁男性于2023年1月向我们报告，头皮（颞区）有两个大的溃疡性肿瘤，左侧下颌区有一个真菌团块。在此之前，他曾在周边医院做过多次切除手术，但肿瘤总是复发。他还在国立医院接受了4个周期的化疗。多学科团队与耳鼻喉科和普通外科医生的努力从治疗开始就至关重要。国立医院的活组织检查显示头皮肿瘤浸润骨的鳞状细胞癌，下颌骨肿瘤的CT扫描显示鳞状细胞癌浸润腮腺，推动左侧外耳道并引起剧烈疼痛。扑热息痛和布洛芬都不能缓解疼痛，我们要求开始给他注射吗啡。伤口包扎时腮腺肿物大量出血，贫血7g/dl，输血3单位血。耳鼻喉科和普通外科医生做减脂手术；下层肌肉被肿块浸润，因此不可能完全切除。一周后，他的头皮肿瘤被切除，出院后他将接受姑息治疗。2023年9月，他在同一部位接受了复发性肿瘤的随访，肿瘤比以前更大。经过肿瘤委员会的几次讨论和请求捐赠后，我们能够获得单克隆抗体Cemiplimab。他开始每两周给药一次，他已经接受了21个周期。从第15个周期开始，他的头皮上只有浅层溃疡，肿瘤明显缩小。没有新的或复发的癌症生长，所有的伤口都愈合了。结论：该病例是一个障碍的例子，尽管它们可能不成功，但由于缺乏像Cemiplimab这样的新型治疗方法，研究证明它在治疗侵袭性cSCC方面是成功的，因此必须在XP中治疗晚期cSCC。XP患者是免疫疗法治疗的完美候选者，这应该在所有情况下可用。[email protected]法国维勒瑞夫巴黎萨克莱大学古斯塔夫·鲁西癌症校区Andrey A. YurchenkoINSERM U981，法国维勒瑞夫巴黎萨克莱大学古斯塔夫·鲁西癌症校区Fatemeh RajabiINSERM U981 [email protected]Tirzah B. P. lajusde Biologia cell e genacei部门，巴西北部格兰德联邦大学Salgado Filho博士，纳塔尔59078-970 [email protected]Hiva国家着色性干皮病服务中心，[email protected]日本神户大学医学院内科内科皮肤科，神户大学研究生院，神户[email protected]Carlos F. M. menck巴西圣保罗大学生物医学科学研究所微生物系，Alain SarasinCNRS UMR9019基因组完整性与癌症，Sergey NikolaevINSERM U981， Gustave Roussy癌症校区，universitparis Saclay, Villejuif， France[email protected] [email protected]色素性干皮病（XP）的特点是由于NER或TLS通路的缺乏导致皮肤癌的风险增加1000倍。导致这种增加的体细胞突变的基因组机制尚不完全清楚。我们对来自易发肿瘤XP亚群（XP- a /C/D/E/V）的独特皮肤肿瘤（n = 38）进行了基因组测序，并建立了体外模型（XP-C/V），通过详细的生物信息学分析阐明紫外线诱导XP突变的机制。在GG-NER （XP-E = 350 mut/MB, XP-C = 162 mut/MB）和翻译合成（XP-V = 248 mut/MB）受损的皮肤肿瘤中观察到超突变的肿瘤表型。伴有NER缺陷的XP皮肤肿瘤的突变谱以C&gt；T突变为主，每组都表现出特定的三核苷酸背景特征。与散发性皮肤癌（4.7%）相比，XP-C和XP-D肿瘤显示CC&gt；TT双碱基替换的比例（17-20%）显著较高。在GG-NER和TC-NER受损的XP-A和XP-D肿瘤中，突变沿染色质基因组区室均匀分布，这表明NER活性是全基因组突变率异质性的主要调节因子。具有功能失调的TLS聚合酶eta的XP-V皮肤肿瘤具有特定的突变特征，包括散发性皮肤癌中缺失的过多的TG&gt；TT取代（28%）。这些突变可能是由于在缺乏聚合酶eta的情况下，TpA和TpG环境中罕见的非典型光斑容易出错而导致的。典型紫外线诱导的嘧啶二聚体C&gt；T突变的突变特征在XP-V肿瘤中是不同的，主要由光二聚体3 '端核苷酸插入错误定义（比散发性癌症高40倍）。这种模式可能反映了不同TLS聚合酶执行的容易出错的插入和无错误的扩展步骤。紫外辐照XPC-KO和POLH-KO细胞系的WGS分析显示，与野生型细胞相比，XPC-KO和POLH-KO细胞系的诱变率分别增加了3倍和11倍。这些发现表明，无差错的TLS旁路在减少紫外线诱导的突变和NER方面发挥着重要的作用，如果不是更大的话。对转染了光致特异性光解酶的细胞系进行的基因组分析强调了CPD在突变产生中的主要作用，以及6-4PP在DNA损伤反应中的主要作用。未转录链上未修复DNA损伤的积累、非特异性TLS活性以及无法无差错绕过非典型光斑共同解释了XP患者皮肤癌发病率增加的原因。大量癌症患者的遗传分析揭示了DNA修复途径基因的体细胞突变与患者对DNA损伤化疗药物和免疫检查点抑制的反应性之间的相关性。与此一致的是，一些病例研究表明，着色性干皮病（XP）黑色素瘤患者对抗pd1治疗反应良好，这表明XP黑色素瘤能够形成免疫有利的肿瘤环境。为了在体内检测核苷酸切除修复（NER）缺陷黑素瘤，我们重点研究了解螺旋酶ERCC2/XPD，并建立了一种带有ERCC2野生型（wt）或ERCC2突变型肿瘤的黑素瘤小鼠模型，这些肿瘤含有有害的点突变K48R或D234N，后者发生在XP患者中。为此，我们设计了小鼠黑色素瘤细胞，首先在体外鉴定，然后转移到C57BL/6J小鼠。正如预期的那样，xpd突变细胞在细胞培养中对紫外线照射和顺铂治疗表现出更高的敏感性。在体内，XPD-K48R黑色素瘤仅在少数病例中发展。XPD-D234N肿瘤发生时间早于XPD-wt肿瘤，这与在基础条件下观察到的XPD-D234N细胞增殖率升高一致。尽管发病迅速，但50%的XPD-D234N黑色素瘤在2-3周内自发消退，这一现象在XPD-wt肿瘤中从未出现过。当携带XPD-D234N黑色素瘤的小鼠联合使用顺铂和PD-1阻断抗体时，几乎所有的肿瘤都消退了，而携带XPD-wt黑色素瘤的小鼠没有观察到治疗反应。这些发现表明，xpd突变型黑色素瘤更容易被宿主免疫系统解决，特别是在ner相关DNA损伤和免疫治疗的情况下。未来的研究将集中在这种增强治疗反应性的分子机制上，为XPD在癌症中的潜在临床应用铺平道路。Tycho E.T. mevissen1,2, Maximilian k<e:1> mmecke3, Ernst W. Schmid1, Lucas farnun3, and Johannes C. Walter1,21哈佛医学院生物化学与分子药理学，哈佛医学院，MA2Howard Hughes医学研究所，细胞生物学，哈佛医学院，主要的转录耦合DNA修复，RNA聚合酶II在DNA损伤处停止导致核苷酸切除修复（TC-NER）的有效激活。这一途径在近40年前被发现，但关于其机制的基本问题仍未得到解答，这在很大程度上是由于缺乏支持这一途径的无细胞系统。我们重现了脊椎动物无细胞TC-NER，并使用该系统研究STK19，这是一种候选TC-NER因子，已知可促进细胞暴露于紫外线后的转录恢复。当含有位点特异性顺铂DNA链内交联的质粒在蛙卵提取物中转录时，观察到无错误修复依赖于规范修复蛋白CSB， CRL4CSA, uvsa， ELOF1和STK19。结构预测和低温电镜显示，STK19是TC-NER复合物的一个组成部分，该复合物与CSA-DDB1、RNA聚合酶II亚基RPB1和TFIIH的XPD解旋酶亚基相互作用。这些界面的突变会破坏无细胞的TC-NER，分子模型表明STK19定位TFIIH，从而将受损的DNA链插入XPD解旋酶中，用于随后的病变验证。总之，我们的新无细胞系统支持真正的真核TC-NER，强烈表明STK19将RNA聚合酶II的停滞与tfiih依赖的下游核苷酸切除修复事件结合起来。Sikandar G. Khan1, Wenelia Baghoomian1, Christiane Kuschal1, Deborah tamur1, Maxwell P. le1, John J. DiGiovanna1, *, Rodrigo Cepeda-Valdes2, Julio Salas-Alanis3, Kenneth H。 11美国国立卫生研究院国立癌症研究所癌症研究中心克雷默癌症生物学与遗传学实验室，马里兰州贝塞斯达，美国2大疱性营养不良表皮松解症研究协会墨西哥基金会，墨西哥蒙特雷；3墨西哥哈利斯科州皮肤病研究所，死亡毛硫营养不良症（TTD）是一种罕见的常染色体隐性多系统发育障碍（百万分之一），其特征是在偏光显微镜下，毛发短而脆，呈横向“虎尾带”。据报道，TTD是由几个不同功能组的基因突变引起的：核苷酸切除修复(NER)/基础转录因子IIH （TFIIH）基因：ERCC2/XPD、ERCC3/XPB和GTF2H5/ TTDA；氨基酸充电tRNA基因（TARS、MARS1、AARS1和CARS）；基础转录因子ⅱE (GTF2E2/TFIIEβ)；x连锁无名指蛋白113A （RNF113A）和一个功能未知的基因（MPLKIP/TTDN1）。我们进行了全外显子组测序，以确定Sabinas脆性头发综合征（一种轻度TTD）的候选基因。我们报道了来自3个不相关家族的5例非光敏成人患者，他们的DBR1 （p.D262Y）编码RNA分枝脱分枝酶DBR1的纯合错义突变（p.D262Y），该酶催化从细胞核前mrna中去除内含子。uv后DNA修复正常，表明DBR1不参与NER/TFIIH。这些细胞的DBR1 mRNA水平降低，没有检测到DBR1蛋白。先前的报道描述了DRB1和TTDN1蛋白的相互作用。我们发现，来自DBR1突变患者的细胞中TTDN1蛋白水平显著降低，而来自TTDN1突变患者的细胞中没有检测到TTDN1蛋白水平。这两种蛋白的稳定性对剪接和转录至关重要。基因分析表明这种突变有一个古老的起源。因此，我们确定DBR1导致Sabinas脆性头发综合征，支持TTD可能由转录损伤引起的假设。Marc Majora, Rituparna Bhattacharjee, Selina Dangeleit, Andrea Rossi, Jean KrutmannIUF - Leibniz-Institut - institute fr umwelt- medizinische Forschung GmbH, d<e:2> sseldorf，德国A型色素性干皮病（XPA）是一种以紫外线过敏、高皮肤癌风险和过早衰老为特征的遗传性疾病，被认为是由核DNA修复缺陷引起的。然而，最近的研究表明，XPA蛋白可能具有核DNA修复以外的功能。通过分析纯化的原代人真皮成纤维细胞（HDF）的线粒体组分，我们发现XPA蛋白位于线粒体内。特别是，当HDF被UVB照射或被促氧化剂甲萘醌处理时，线粒体XPA含量增加，这表明XPA可能对修复线粒体内部损伤和保护线粒体完整性很重要。因此，从XPA患者获得的HDF （XPA HDF）的线粒体DNA （mtDNA）测序显示，与健康的HDF相比，突变负荷升高，UVB照射进一步增加了突变负荷。这些数据表明，XPA不仅参与核DNA的修复，还参与mtDNA的修复。RNA-Seq转录组分析也反映了XPA在维持线粒体功能方面的关键作用，显示“线粒体基因表达”和“线粒体翻译”是uvb照射下XPA HDF中受到最严重抑制的生物过程。为了评估对线粒体功能的潜在影响，我们接下来测量了细胞ATP产生率。我们发现未辐照的XPA HDF比健康的HDF有更高的总ATP产生率，这是由于线粒体增加而不是糖酵解ATP产生率。如果细胞受到UVB照射，XPA HDF中的线粒体ATP生成率降低50%以上，而在正常HDF中则保持稳定。因此，XPA HDF对ATP的需求增加，这在非应激细胞中仍然可以通过线粒体功能来满足。辐照后，补偿失效，XPA HDF能量不足。由于伴侣蛋白HSP90作为ATP传感器，以ATP依赖的方式稳定蛋白，我们接下来分析了HSP90客户蛋白的丰度。HSP90水平保持不变，但与健康的HDF相比，辐照的XPA HDF中检测到ErbB2、EGFR、STAT3和SIRT1的明显缺失，反映了蛋白质停滞的崩溃。我们的研究结果表明，XPA蛋白存在于线粒体中，在那里它们维持mtDNA的完整性和线粒体功能，以确保细胞ATP供应，从而防止蛋白质平衡的崩溃，这是众所周知的衰老驱动因素。 Paola Giunti, Hector Garcia-Moreno, Douglas R Langbehn, Adesoji Abiona, Isabel Garrood, Zofia Fleszar, Marta Antonia Manes, Ana M Susana Morley, Emma Craythorne, Shehla Mohammed, Tanya Henshaw, Sally Turner, Harsha Naik, Istvan Bodi, Robert P E Sarkany, Hiva Fassihi， Alan R lehmann国家着色性干皮病服务，圣约翰皮肤病学研究所，盖伊和圣托马斯基金会信托基金，伦敦se17eh，基因组损伤和稳定性中心，着色性干皮病（XP）由参与DNA修复系统的八种基因中的任何一种的双等位基因突变引起，从而定义了八种不同的基因型（XPA、XPB、XPC、XPD、XPE、XPF、XPG和XP变体或XPV）。除了皮肤和眼科特征外，一些患者还存在XP神经系统疾病。目前尚不清楚不同的神经症状及其进展是否在各组之间有所不同。因此，我们的目的是表征XP神经系统疾病及其在异质英国XP队列的演变。从2009年到2021年，英国国家XP服务中心对XP患者进行了随访。记录不同事件的发病年龄。用共济失调评定量表（SARA）、非共济失调体征量表（INAS）和日常生活活动问卷（ADL）对小脑性共济失调和其他神经系统体征和症状进行评定。患者的突变根据其预测的影响得到评分。从可用的辅助试验中收集数据。共招募了93例XP患者。36例（38.7%）报告了神经系统症状，尤其是XPA、XPD和XPG组，有早发和晚发形式，通常出现在皮肤和眼科症状之后。XPA、XPD和XPG患者SARA评分高于XPC、XPE和XPV。随着时间的推移，XPD（0.91分/年，95%可信区间：0.61,1.21）和XPA（0.63分/年，95%可信区间：0.38,0.89）的SARA总分显著升高。反射减退、触感减退、上运动神经元征象、舞蹈病、肌张力障碍、动眼肌征象和认知障碍是XPA、XPD和XPG的常见表现。小脑和全脑萎缩、轴突感觉和感觉运动神经病变以及感觉神经性听力损失是患者的常见表现。一些XPC、XPE和XPV病例在检查和/或辅助检查中表现异常，提示潜在的神经系统受累。更严重的突变与XPA的SARA总分（严重性评分每1单位增加0.40分/年）和XPD（每1单位增加0.60分/年）以及XPA的ADL总分（每1单位增加0.35分/年）的更快进展相关。有症状和无症状形式的神经系统疾病在XP患者中很常见，神经系统症状可能是导致残疾的重要原因。通常情况下，神经系统疾病之前会有皮肤和眼科特征，这些特征应该在特发性迟发性神经系统综合征患者中积极寻找。评估小脑功能，尤其是行走和语言功能，以及残疾的量表可以显示出某些群体的进展。突变严重程度可作为临床试验中分层目的预后生物标志物。德国雷根斯堡大学医院皮肤科人类基因组不断暴露于各种来源的DNA损伤中。对这种损害的无效保护会导致遗传不稳定，最终导致躯体疾病、早衰和癌症。因此，我们的生物体有许多高度保守和有效的机制来负责DNA修复。如果这些修复机制由于相关基因的种系突变而存在缺陷，则可能出现DNA修复缺陷的罕见疾病。今天，以DNA修复机制的遗传缺陷为特征的少数罕见遗传性疾病是已知的，包括共济失调毛细血管扩张症、奈梅亨断裂综合征、维尔纳综合征、布鲁姆综合征、范可尼贫血、科凯恩综合征、毛营养不良症以及着色性干皮病。尽管这些罕见疾病在特定症状方面存在异质性，但它们具有许多共同的临床特征，如生长迟缓、神经系统疾病、过早衰老、皮肤改变（包括异常色素沉着）、毛细血管扩张、皮肤干燥、病理性伤口愈合以及患不同类型癌症的风险增加。更好地了解这些疾病的潜在分子病理学，已经产生了潜在的治疗方法。在这次演讲中，我们将讨论不同的治疗途径和作用方式，从治疗潜在的机制到治疗这些患者的不同节段性临床症状。 Nihan Erden1， Björn schumacher11衰老与疾病基因组稳定性研究所，衰老相关疾病细胞应激反应卓越集群（CECAD），科隆大学dna损伤是癌症发展和衰老过程的一个原因。肿瘤抑制因子p53是DNA损伤反应（DDR）的中心介质，也是人类癌症中最常见的突变基因。许多研究表明，p53的细胞周期和凋亡功能在防止肿瘤发生发展中起重要作用，p53的激活可根据DNA损伤的类型和严重程度进行细胞自主调节。近年来研究发现，干细胞中p53介导的DDR不仅受细胞自主调控，而且还通过小生境细胞的信号传导进行调控。当原始生殖细胞携带DNA损伤时，秀丽隐杆线虫的翻译起始因子IFE-4在原始生殖细胞周围的体细胞性腺前体生态位细胞中被激活。此外，研究表明，哺乳动物中IFE-4同源基因eIF4E2在紫外线诱导的DNA损伤后在生态位细胞中被诱导，并且是在毛囊干细胞（HFSCs）中诱导p53所必需的。因此，这些数据表明了干细胞中p53介导的DDR的非细胞自主调节的高度保守机制。我们目前正在使用eIF4E2表皮特异性敲除小鼠的体内和离体实验系统来剖析生态位和干细胞之间相互作用的机制，并了解eIF4E2在皮肤稳态和致癌中的作用。为了进一步评估eIF4E2功能的临床相关性，我们将表征eIF4E2在人类鳞状细胞癌中的作用。英国伦敦盖伊和圣托马斯基金会信托基金会圣约翰皮肤病研究所光皮肤学系Hiva博士、英国国家色素性干皮病服务中心教授、英国布莱顿法尔默萨塞克斯大学基因组损伤与稳定中心Alan lehmann教授、英国布莱顿BN1 9RQ、100多名色素性干皮病（XP）患者、30多名柯凯因综合征（CS）患者、13名毛硫营养不良（TTD）患者在英国国家核苷酸切除修复（NER）多学科服务中心接受长期随访。英国患者支持团体的参与，行动XP和艾米和朋友，是至关重要的照顾这些病人。由临床医生、护士和科学家组成的专家小组的目标是改善临床结果，降低发病率和死亡率。在过去的14年里，与美国国立卫生研究院（National Institutes of Health）分析1971年至2009年全球文献的106名患者的数据相比，英国XP患者的预期寿命有了显著改善。在英国，没有神经退行性变的XP患者现在的预期寿命与普通英国人口相当，因为早期诊断，细致的光保护和及时诊断和治疗任何皮肤癌和眼部癌症。功能研究和分子分析以确定NER基因的致病变异（专家服务的一部分）使这些患者能够进行详细的基因型-表型检查。对疑似病例进行仔细的临床评估，发现了一个新的XP互补组XP- j，该组具有GTF2H4基因突变，并有助于报道与CS表型相似的morc2相关疾病。在多学科门诊就诊的患者中，有几组患者的表型相对较轻。在大多数情况下，在XP-A、D和G中，它们与剪接供体位点（在不变的GT核苷酸之外）的突变有关，导致大多数mRNA的剪接异常，但仍有少量正常剪接的mRNA。由此产生的少量正常蛋白足以改善或延缓临床特征的发生。在4例CS患者中，剪接供体位点第5个碱基的G突变导致临床特征的显著延迟发作。荷兰鹿特丹Erasmus大学医学中心分子遗传学和Oncode研究所的Jurgen martein教授Marvin van Toorn说，核苷酸切除修复（NER）通过一种“切割-修补”型DNA修复反应来保持基因组的稳定性。尽管最初的NER反应步骤（通过双切口依次识别、验证和切除螺旋扭曲的DNA损伤）已经得到了很好的表征，但对随后如何恢复产生的ssDNA缺口的机制了解仍然有限。在这里，我们研究了这一后期切口后NER步骤的机制和因素。我们发现，RFC介导PCNA在ner生成的ssDNA间隙的招募和装载，之后POLD3取代RFC招募POLD1并使polδ依赖性修复合成成为可能。随后，lig3介导的缺口连接促进ATAD5-RLC卸载PCNA，这有助于PCNA再循环到新的ner生成的ssDNA缺口。有趣的是，我们发现在积极复制的细胞中，DNA损伤位点的PCNA和polδ募集严重减少。这可以解释一个平行的、非冗余的、不依赖于pcna的间隙恢复途径的存在，该途径涉及可选的箝位加载器CTF18-RLC、polε和LIG1。总的来说，我们的研究为通过在整个细胞周期中协调ner生成的ssDNA间隙的生产性恢复来保持基因组完整性的复杂机制提供了重要的见解。Chikako Nishigori1， Mariko Tsujimoto1和Shinichi moriwaki21日本神户大学医学研究生院内科内科皮肤科2大阪医科大学皮肤学系着色性干皮病（XP）是一种常染色体隐性DNA修复疾病，以光敏性和进行性中枢和周围神经系统损伤为特征。目前，除了避免紫外线照射外，没有有效的治疗XP的方法。研究表明，XP细胞清除活性氧和氧化性DNA损伤的能力受损。因此，研究了几种抗氧化剂降低XP-A细胞氧化应激引起的细胞毒性。由于体外实验显示n -乙酰基-5-甲氧基色胺和烟酰胺可降低自由基诱导剂引起的XP-A细胞的细胞毒性，我们进行了体内实验，研究n -乙酰基-5-甲氧基色胺的治疗潜力。n -乙酰-5-甲氧基色胺治疗可减轻紫外线诱导的炎症、皮肤肿瘤发生和XP模型小鼠的听力下降。结果表明，n -乙酰基-5-甲氧基-色胺可通过抗炎和抗氧化作用减轻XP症状。<https://www.sciencedirect.com/science/article/pii/S0923181125000039>.Therefore，我们通过一项多中心、双盲、安慰剂对照、两组交叉研究，对n-乙酰基-5-甲氧基色胺（NPC-15）治疗重度晒伤反应型XP患者的疗效进行了临床试验，随后进行了52周的开放研究。伦理审批由神户大学机构审查委员会和大阪医药大学机构审查委员会监督，研究按照批准的方案（日本临床试验登记处（jRCT）标识符：jRCTs051210181）进行。于2022年2月23日注册。临床试验于2022年4月至2023年12月进行。20例患者(年龄；10.6±6.8,F / M;12/8)。18例为XP-A。钥匙打开后，对所有数据进行分析统计。在主要终点MED中，在研究药物给药的第15天（交叉期I和交叉期II）紫外线照射后72小时（+/-6小时），NPC-15给药的治疗效果与安慰剂给药相比没有统计学上显著的改善。从个体患者的角度来看，数据表明一些项目有用，包括XP的神经严重程度量表评分。NPC-15没有明显的安全问题。通过下面的URL可以获得简短的摘要。<https://jrct.niph.go.jp/latest-detail/jRCT2051210181>.Melanie van der Woude, Karen L. Thijssen, Mariangela Sabatella, Jurgen A. Marteijn, Wim Vermeulen， Hannes lans荷兰鹿特丹Erasmus MC分子遗传学系多功能核苷酸切除修复（NER）途径保护生物体免受各种螺旋扭曲DNA损伤的有害影响。遗传性NER缺乏可引起几种人类癌症易感和/或类早衰疾病，包括色素干皮病、Cockayne综合征、毛硫营养不良症或这些疾病的组合。目前尚不清楚相同DNA修复途径中的缺陷如何导致不同的疾病特征和严重程度。为了更好地了解不同NER疾病的发病机制，我们利用人类细胞和秀丽隐杆线虫模型系统来研究DNA修复的机制及其在体内的影响。我们之前报道过核心NER机制持续靶向携带严重NER疾病突变的人类细胞中的DNA损伤。本研究通过实时成像显示，不同类型的NER缺乏对核心NER因子与DNA损伤结合的影响不同，特异性NER因子与DNA损伤结合的时间延长与NER疾病的严重程度相关。利用秀丽隐杆线虫，我们发现DNA损伤可引起强烈的发育阻滞和神经元功能障碍，这取决于转录偶联DNA修复和特异性DNA修复中间体在没有修复的情况下的持久性。总之，这些结果确定停滞转录偶联的NER中间体是NER缺乏的致病特征，并表明这些对组织功能和生物体发育产生不利影响。 Vilhelm A bohr哥本哈根大学，健康老龄化中心，和以前的国家老龄化研究所，nih我们发现一些DNA修复缺陷疾病与严重的神经退行性疾病有线粒体功能障碍。我们的研究涉及细胞系、蠕虫（秀丽隐杆线虫）和小鼠模型，包括早衰综合征色素性干皮病A组、Cockaynes综合征、共济失调毛细血管扩张症和Werner综合征。它还包括阿尔茨海默病（AD）模型。在这些条件下，我们发现了一种超聚合、NAD+和Sirtuin信号缺乏和线粒体应激的模式，包括线粒体自噬缺陷作为一个突出特征。补充NAD可以刺激线粒体功能，包括线粒体自噬，并刺激DNA修复途径。柯凯因综合症（CS）小鼠的听力缺陷反映了患者的听力缺陷。短期补充NAD与NR可减少听力损失。这种听力损失与年龄相关性听力损失类似。用NR治疗小鼠可改善与年龄相关的听力损失。目前对CS小鼠的研究显示肾脏疾病反映了许多CS患者的情况，并且小鼠在NAD合成途径中存在缺陷。NAD干预的临床试验显示对AT患者有益，目前对Werner患者的干预研究也显示出一些益处。这些将被讨论。Giulia Brancaa, Debora Ferria, Manuela Lanzafamea, Erica Gandolfia, Gianluca Guidaa, Tiziana Nardoa， E. Bottaa和Donata oriolia .分子遗传学研究所（IGM） L.L. Cavalli Sforza， CNR, 27100 Pavia， italy多蛋白复合物TFIIH是转录和核苷酸切除修复（NER）途径的关键因子。TFIIH功能障碍导致不同的常染色体隐性遗传病，包括易患癌症的着色性干皮病（XP）和多系统毛硫营养不良症（TTD），后者的特征是身体和智力发育迟缓，有早衰的迹象，但没有皮肤癌。XP和TTD细胞的特征都是对紫外线辐射过敏，损伤部位的NER蛋白持续存在，以及未修复的DNA损伤的积累。我们已经证明TTD细胞比XP细胞更容易遭受广泛的转录失调。这是否与ttd特异性突变引起的TFIIH功能失调有关，还是与所有引起ttd的突变都会影响整个复合物的稳定性并导致TFIIH数量减少有关，仍然是一个悬而未决的问题。通过低温或化学处理稳定TFIIH可以部分恢复热敏性TTD患者（其临床特征随着发热发作而恶化）原代细胞的TFIIH功能，这一发现向我们提示了保存人类细胞中TFIIH量的相关性。我们现在已经确定了一种新的含有tfiih的多蛋白组合，它与染色质结合，其功能是在转录过程中协助RNA聚合酶II。野生型TFIIH或蛋白质组装的其他成分水平降低导致转录改变，类似于在TTD中观察到的。总的来说，我们的研究结果表明，定量和定性的TFIIH改变有助于广泛的TTD临床特征。Kenneth H. Kraemer1, Deborah tamur2, Sikandar G. Khan, John J. digiovann31美国国立卫生研究院癌症生物学和遗传学实验室，Bethesda， MD， USA退休人员2退休3去世色素沉着性干皮病（XP）的研究于1971年在美国国立卫生研究院开始，以深入了解临床疾病和DNA损伤和修复机制。对皮肤和眼睛异常、神经变性、听力丧失、皮肤和内部癌症以及衰老进行了详细的临床和实验室检查。我们在国家卫生研究院和校外的科学家合作。结果包括发现5个切除修复（ER）缺陷的XP补体组，ER熟练的XP变体，并测量了&gt；皮肤癌和眼癌的发病率增加了1000倍。我们开发了宿主细胞在紫外线下存活和诱变的再激活实验，发现一种DNA二聚体在XPA细胞中失活表达。口服类维生素a治疗的XP患者首次证明了人类有效的癌症化学预防。用听力图评估XP神经退行性变的发生率。尸检显示，成年XP患者的婴儿脑证明了XP引起的大面积萎缩。内部癌症包括脑和脊髓肿瘤、甲状腺癌、白血病、淋巴瘤和肺癌（吸烟者）。过早绝经是衰老的一个特征(中位年龄29.5岁；比美国人口年轻20岁)。我们发现XPA患者有严重、中度或轻度疾病。XPD基因突变的毛硫营养不良（TTD）患者发育异常，包括脑髓磷脂缺失、多发性感染、骨骼异常、髋关节无菌性坏死和过早死亡，但皮肤癌发生率未增加。患有XPD突变的TTD儿童的母亲有许多妊娠异常，而患有XPD突变的XP儿童的母亲妊娠正常，从而将XPD功能与人类胎儿发育联系起来。我们发现了两个新的RNA相关的TTD致病基因：TFIIE2和DBR1。1985年，我们与V. Bohr博士一起建立了DNA修复兴趣小组，每月召开视频会议（在http://videocast.nih.gov上存档了数百次），并发起了这一系列国际XP会议的前3次会议（2004年，2006年和2010年）。NIH和世界范围内对XP的深入研究在理解疾病机制方面取得了进展，最重要的是，提高了患者的健康水平，延长了他们的预期寿命。XP患者过早死亡的最常见原因是转移性皮肤癌(1)，80%的XP患者的皮肤癌发生在面部、头部和颈部(2)。因此，严格和绝对的紫外线防护对于XP患者的治疗至关重要，尤其是面部。我们最近使用了一种新的方法来准确估计长时间到达面部皮肤的紫外线日剂量，并使用该方法详细研究了英国36名XP患者在3周内的光保护行为。我们发现紫外线防护的范围很广（即每天对面部的紫外线剂量），大约35%的成年XP患者的防护明显比其他人更差(3)。我们继续证明，较差的光防护与9个变量密切相关。其中7个是潜在可逆的心理因素(4)。我们接着设计了一种个性化的行为改变干预（“XPAND”），以针对这些与光防护能力差（即每天对面部的紫外线剂量高）相关的心理因素。它包括由护士或心理学家提供的7个一对一的课程。在这次讲座中，我将介绍我们对16名光保护不良的XP患者进行这种干预的随机对照试验的结果。设计为双臂平行组随机对照试验，延迟干预对照组次年接受XPAND治疗。主要终点是在6月或7月的3周期间，在XPAND（或对照组无干预）期间，面部的平均每日紫外线剂量。在16例随机分组的患者中，13例为主要结局分析提供了足够的数据。XPAND组（n = 8）面部的平均每日紫外线剂量低于对照组（p<0.001）。延迟干预对照组干预后面部的平均日剂量也低于干预前，但没有统计学意义上的显著水平。次要终点也进行了分析。还进行了卫生经济分析并预测，通过降低与紫外线照射相关的长期治疗费用，扩展和治疗是一种具有成本效益的治疗方法。在这次演讲中，我将讨论这些数据，从这个小型随机对照试验中可以得出什么和不能得出什么结论，以及对XP临床管理的影响。Alain Sarasin1, Andrey a . Yurchenko2和Sergey Nikolaev21UMR9019 CNRS， Gustave Roussy和Paris-Saclay大学，法国维勒瑞夫2 inserm U981， Gustave Roussy和Paris-Saclay大学，法国维勒瑞夫色素沉着病（XP）是一种罕见的常染色体隐性遗传病，由切除核苷酸修复（NER）缺陷引起。这些患者对阳光极其敏感，导致暴露在阳光下的身体部位患皮肤癌的频率增加。由于持续的光保护和更好的治疗教育，XP患者的寿命比过去更长。最近发现部分XP患者发生内部肿瘤的风险非常高，包括中枢神经系统、血液系统恶性肿瘤、妇科和甲状腺癌（Nikolaev et al., Orphanet J. Rare Dis., 2022, 17,104）。我们分析了四个已发表的、国际性的、临床定义明确的XP队列（来自美国、法国、英国和巴西），并计算了这些患者的癌症风险。对于0-20岁的法国xp来说，年轻xp的比值比（OR）非常高（比一般人群高出一千多倍）。在英国、法国和美国的xp中，也观察到发展中的脑肿瘤、血液恶性肿瘤和甲状腺肿瘤的高OR。在XP患者中，最容易发生内部肿瘤的是XP- c组患者，特别是那些携带来自北非的创始XPC突变的患者(Sarasin et al., Blood, 2019, 133,2718；癌症杂志，2023,15,2706)。我们通过全基因组测序分析了22例XP患者的内部肿瘤，主要是血液恶性肿瘤、妇科肿瘤和甲状腺肿瘤。结果显示XP-C肿瘤的突变率与散发性肿瘤相比显著增加。在转录和基因表达水平方面，强烈的突变不对称性证明了人类体内转录偶联修复的存在。突变似乎是由DNA未转录链上未修复的大块鸟嘌呤损伤引起的(Yurchenko等人，Nature Comm., 2020, 11,5834；尤尔琴科等人，普通医学，2023,3,109)。内部XP-C肿瘤的突变谱对ner缺乏非常特异性，并且在所有XP-C内部肿瘤中几乎相同，无论肿瘤类型如何，与组织匹配的散发性肿瘤完全不同。跟踪XP患者的医生应该意识到内部肿瘤的高风险。预防和早期发现白血病和脑、妇科、甲状腺肿瘤是必要的。筛查应该从10-12岁左右开始每年进行一次（例如，一些XP-C患者在MDS/白血病前几年出现早期贫血）。Diana van den heuvel1,11, Marta Rodríguez-Martínez2,11, Paula J. van der meer1,11, Nicolas Nieto Moreno3, Jiyoung Park4, hyon - suk Kim4, Janne J.M. van Schie1, Annelotte P. Wondergem1, Areetha D'Souza4, George Yakoub1, Anna E. Herlihy2, Krushanka Kashyap3, Thierry boissi<e:1>, 2,3, Jane Walker2, Richard Mitter6, Katja Apelt1, Klaas de Lint7, Idil Kirdök7, Mats ljungman8,9, Rob M.F. Wolthuis7, Patrick Cramer10, Orlando D. Schärer4,5, Goran kokic10,12, Jesper Q svejstrup2,3,12，1121荷兰莱顿大学医学中心人类遗传学系2转录机制实验室3哥本哈根大学细胞与分子医学系Blegdamsvej 3B， 2200丹麦哥本哈根4韩国蔚山基础科学研究所基因组完整性研究中心5蔚山国立科学技术研究所生物科学系，蔚山韩国6生物信息学和生物统计学，弗朗西斯克里克研究所，1米德兰路，伦敦，nw1at，英国；7临床遗传学，肿瘤遗传学，阿姆斯特丹癌症中心，阿姆斯特丹大学医学中心，阿姆斯特丹，荷兰；8放射肿瘤学，密歇根大学，安阿伯，美国；9环境健康科学系，Rogel癌症中心和RNA生物医学中心，密歇根大学，安阿伯，密歇根州；USA10Max Planck多学科科学研究所，分子生物学系，37077 Göttingen, Germany.11这些作者有相同的贡献12高级作者转录偶联DNA修复（TCR）去除阻碍RNA聚合酶II （RNAPII）转录的大体积DNA损伤。最近的研究概述了TCR因子CSB、CSA、uvsa和TFIIH在病变停滞的RNAPII周围的逐步组装。然而，过渡到下游修复步骤所需的机制和因素，包括去除RNAPII以提供修复蛋白进入DNA损伤的途径，仍不清楚。在这里，我们确定STK19是促进这种转变的TCR因子。STK19的缺失不会影响TCR复合物的初始组装或RNAPII泛素化，但会延迟损伤停滞的RNAPII清除，从而干扰下游修复反应。Cryo-EM和突变分析显示STK19与TCR复合物相关，定位于RNAPII、uvsa和CSA之间。结构分析和分子模型表明，STK19将TFIIH的atp酶亚基定位在RNAPII前面的DNA上。总之，这些发现为TCR所需的因素和机制提供了新的见解。 3苏塞克斯大学基因组损伤与稳定性研究中心，英国布莱顿BN1 9RQ。简介：着色性干皮病（XP）是一种罕见的DNA修复常染色体隐性遗传病，其特征是对紫外线辐射极度敏感。患者有患皮肤癌、眼表疾病的风险，大约三分之一的患者经历进行性神经退行性变。预期寿命因补充组、疾病严重程度和获得预防措施的机会而有很大差异。获得这种罕见和遗传异质性疾病的可靠生存估计可能具有挑战性，导致报告的存活率存在差异。美国国立卫生研究院（National Institutes of Health）对106名患者（1971年至2009年）进行的一项研究显示，伴有神经退行性变的XP患者的中位死亡年龄为29岁，未伴有神经退行性变的患者的中位死亡年龄为37岁(1)。这些统计数据经常被学术文献引用，并在可公开访问的网站上广泛报道。目的：评估在英国国家XP服务中心接受多学科治疗的XP患者的预期寿命，并评估患者和家属对其预后的了解。方法：从2015年到2024年，我们对英国国家XP服务每年检查和治疗的89例患者进行了纵向研究。死亡事件被记录下来，并在有和没有神经退行性变的人之间进行分类。为了评估患者对预期寿命的看法，24名临床参与者（16名神经系统未受影响的患者和8名亲属）在2023年2月至7月之前完成了一项简短的调查。结果：在9年的时间里，我们记录了15例死亡（17%），包括11例神经退行性变（a、B、D、F和G组）和4例非神经退行性变（a、C和V组）。值得注意的是，没有死于皮肤癌。4例死亡与内部恶性肿瘤有关[中位年龄：52.5岁（IQR 41.8-58.75）]。神经系统受累患者的中位生存年龄为50年（95% CI [34, Inf]），无神经系统受累患者的中位生存年龄为81年（95% CI [81, Inf]）。后者与英国一般人群相当（男性78.6岁，女性82.6岁，2020-2022年）(2)。对于神经系统受累的个体，40岁以上的估计生存概率为0.68 (95% CI[0.47,0.98])，对于没有受累的个体，估计生存概率为0.90 （95% CI[0.73,1.00]）。24名受访者中只有11人（46%）认为未受神经系统影响的XP患者的预期寿命是正常的。1名受访者（4%）估计预期寿命为20-29岁，8名受访者（31%）估计为30-39岁，1名受访者（4%）估计为50-59岁，3名受访者表示不确定。结论：我们提供的证据表明，与之前报道的文献相比，英国XP患者的生存结果有所改善，无论有无神经系统受累。虽然XP患者的预期寿命可能有限，特别是在没有适当护理的情况下，但医疗管理的进步和严格遵守预防措施改善了结果。重要的是，更新网上过时的和潜在有害的错误信息，并通过与患者和家属的讨论向他们传达，定期的医疗随访，认真的光保护，及时干预皮肤癌，可以延长XP患者的寿命和生活质量。参考文献：Bradford PT， Goldstein AM, Tamura D, Khan SG, Ueda T, Boyle J, Oh KS, Imoto K, Inui H, Moriwaki S, Emmert S, Pike KM, Raziuddin A, Plona TM, DiGiovanna JJ, Tucker MA, Kraemer KH。色素性干皮病的癌症和神经退行性变：DNA修复的长期随访特征。中华医学杂志，2011;48(3):168-76。doi: 10.1136 / jmg.2010.083022。Epub 2010 11月19日。PMID: 21097776;PMCID: PMC3235003。英国国家统计局（ONS），发布于2024年1月11日，ONS网站，统计公报，国家生命表-英国人的预期寿命：2020年至2022年alexandra Paolino1， Sally Turner1, Tanya Henshaw1, Joanne Palfrey1, Karla Balgos1, Paola Giunti, Ana M. S. Morley1, Shehla Mohammed1, Adesoji Abiona1, Alan R. lehman2， Hiva fassihi11国家着色性干皮病服务，英国伦敦SE1 7EH，英国；2英国苏塞克斯大学Falmer， Brighton BN1 9RQ。简介：在互补组之间和互补组内，色素性干皮病（XP）的临床表现具有明显的异质性。有效的管理依赖于早期诊断，严格的光保护以减轻皮肤癌相关的发病率和死亡率，以及定期的皮肤和眼科检查以及时发现和治疗恶性肿瘤。尽管采取了这些措施，诊断延误仍然是一个挑战，强调需要提高卫生保健提供者的认识。目的：探讨XP的临床表现及从首发症状到诊断的时间。方法：对133例XP患者进行回顾性分析，其中女性67例，男性66例；年龄范围0-87岁)在国家中心接受多学科专科治疗。其中100名患者被纳入研究，排除了29名通过哥哥姐姐诊断的患者和4名病史不完整的患者。收集的数据包括互补组，呈现的临床特征分为皮肤、眼科或神经学症状、症状发作年龄、诊断年龄和转诊专科。结果：所代表的互补组包括XP-A （n = 20）、XP-B （n = 2）、XP-C （n = 29）、XP-D （n = 14）、XP-E （n = 6）、XP-F （n = 6）、XP-G （n = 7）、XP-V （n = 16）。到3岁时，84%的患者出现了该病的临床症状（不包括那些出现皮肤癌的患者），但诊断时的平均年龄为12.2岁(中位数为6岁；0.5-64年)。初始临床症状差异显著。暴露部位色素改变出现在平均5岁（0.5-44岁），主要见于XP-C（83%，平均2.3岁，范围0.75-6岁）和XP-V（56%，平均14.4岁，范围2-44岁）患者。光敏性，以严重的长时间晒伤为特征，是XP-D（100%）、XP-F（100%）、XP-G（86%）和XP-A（55%）患者的主要症状，不包括那些较轻的XP-A变异。这些补充组的中位诊断延迟较短（范围为3.2-11年）。首发时的皮肤癌在XP-E（66%，平均年龄26岁，范围15-40岁）、XP-V（44%，平均年龄35岁，范围16 - 46岁）和XP-C（7%，平均年龄16岁，范围4-28岁）中最为常见。两名年龄分别为0.5岁和1岁的XP-C患者的首要表现为眼部征象，包括结膜炎和畏光。两名XP-A患者在两岁时表现出发育迟缓，其最初表现为神经系统症状。XP-E和XP-V患者的诊断延迟尤为明显，中位延迟分别为28.5年和21.5年。皮肤科医生是最常见的转诊医生，占73%，其次是遗传学家（7%）、全科医生（10%）、儿科医生（5%）、神经科医生（3%）和眼科医生（2%）。结论：大多数XP患者在生命早期表现出临床症状，但存在明显的诊断延迟，特别是在皮肤症状较轻的人群中，缺乏严重的晒伤反应或色素改变。皮肤科医生是主要的转诊者，强调他们在早期识别中的关键作用。提高对所有专业的认识对于改善XP患者的诊断时间表和结果至关重要。Guzzon Diletta1*, Paccosi Elena1*, Filippi Silvia1, Valeri Emma1， De Lanerolle Primal2和Proietti-De-Santis Luca1#1衰老分子遗传学单元，Tuscia大学生态与生物学系，01100 Viterbo, italy .2伊利诺伊大学芝加哥分校医学院生理与生物物理学系，835 S. Wolcott，芝加哥，IL 60612。柯凯因综合征A组（CSA）是一种泛素E3连接酶，属于WD-40重复蛋白家族。CSA最初被描述为与Cockayne综合征B组（CSB）蛋白一起在转录偶联修复中发挥作用，即使在过去的几年里，越来越多的证据表明这种蛋白与CSB一起在泛素化和蛋白酶体降解中发挥关键作用，这些蛋白质参与了最不同的细胞过程。CSA和CSB的突变导致柯凯因综合征（CS），这是一种人类常染色体隐性遗传病，以多种临床特征为特征，包括生长缺陷和严重的神经和发育表现。肌动蛋白（Actin）是细胞质的主要组成部分，最近发现其丝状形式（F-Actin）在细胞核中也大量存在，参与多种核过程，包括转录和染色质重塑。肌动蛋白的核输出是由染色体维持1或输出蛋白1 （CRM1）介导的。在这里，我们证明CSA可以通过泛素化其核出口蛋白CRM1来调节肌动蛋白的核定位，从而避免CRM1/肌动蛋白复合物通过核孔复合物。我们还证明，CS-A患者衍生的成纤维细胞显示肌动蛋白核保留受阻，有利于其核输出，这是CRM1泛素化缺陷的结果。这种肌动蛋白定位的不平衡导致细胞骨架形状的改变和僵硬，以及核肌动蛋白病灶的急剧减少。此外，正常细胞表现出CRM1在核膜上的优先定位，而CS-A突变细胞表现出CRM1作为细胞质病灶的异常存在，进一步证实了CRM1介导的输出率异常。如何调和核肌动蛋白输出缺陷与柯凯因综合征的特征？众所周知，核肌动蛋白定位于某些基因的启动子，在那里它帮助募集或RNA聚合酶II （RNA polII）。有趣的是，在CS-A突变患者的衍生成纤维细胞中，我们发现一些基因（如BDNF和BRD7）启动子上的Actin募集受阻，这与相同启动子上的RNA polII募集缺陷以及这些基因的转录缺陷相对应。这些结果可能潜在地证明了CS-A患者表现出的转录缺陷，特别是在神经发育表现方面。目前尚不清楚CSB是否以某种方式参与了这一新的调控途径，可能是核输出蛋白CRM1降解的原因。需要进一步的研究来更好地定义CSB的最终作用以及肌动蛋白穿梭损伤对CS患者临床特征的影响。Silvia Filippi, Emma Valeri, Elena Paccosi， Diletta Guzzon和Luca Proietti De santiit，意大利图西亚大学生态与生物学系，01100 ViterboCockayne综合征（CS），定义为核苷酸切除修复（NER）综合征，是一种罕见的常染色体隐性遗传病，与ERCC8和ERCC6基因突变有关，ERCC8和ERCC6基因分别编码CS a组（CSA）和B组（CSB）蛋白，这两个基因都在转录偶联修复（Transcription Couples repair， TCR）中起作用，这是NER的一个亚途径，致力于去除转录基因上的病变。虽然CS患者对紫外线照射表现出过敏，但与另一种被定义为色素性干皮病的NER综合征相比，他们发生皮肤癌的风险并不增加。虽然ERCC8和ERCC6基因的功能缺失突变会导致各种衰老和细胞死亡相关的异常，但据报道，在来自不同组织的癌细胞中，CSA和CSB蛋白的表达增加通常与增殖和细胞稳健性增加有关。最近，我们发现CSA蛋白在乳腺癌细胞中过表达，通过ASO技术下调CSA蛋白，不仅显著降低了乳腺癌细胞的致瘤性，而且增强了乳腺癌细胞对奥沙利铂和紫杉醇这两种三阴性乳腺癌亚型主要化疗药物的致敏性。在这条线上，我们决定分析CSA在原发性（WM115）和转移性（WM266-4）黑色素瘤细胞中的表达。黑色素瘤是最具侵袭性的皮肤癌。在过去的几年里，研究已经取得了很大的进步，通过引入创新和有效的治疗方法：免疫治疗和靶向治疗，不幸的是，一些类型的黑色素瘤是难以治疗的。在这种情况下，传统的甲基化药物化疗：达卡巴嗪（DTIC）和替莫唑胺（TMZ）被认为是最后的选择。DTIC和TMZ都与尚不清楚的生存获益和治疗相关的毒性有关。我们的研究表明，WM115和WM266-4细胞均表现出CSA的过表达。此外，CSA抑制使两种细胞系，特别是转移性细胞系，对达卡巴嗪（DTIC）和替莫唑胺（TMZ）药物都有很大的敏感性，即使在对正常细胞无害的非常低剂量下，在细胞增殖、细胞存活和凋亡反应方面也是如此。此外，研究必须评估CSA是否可以被认为是一个非常有吸引力的目标，以开发更有效的抗黑色素瘤疗法。细胞综合生物学研究所（I2BC）， CEA - CNRS - University Paris-Saclay， 91191 Gif-sur-Yvette france转录和DNA修复是细胞的基本功能。它们的功能失调导致细胞死亡、突变和病理。在NER中，转录偶联修复去除干扰RNA聚合酶II进展的DNA损伤。遗传性NER缺陷可导致色素性干皮病、Cockayne综合征和三硫代营养不良，并伴有包括阳光敏感、皮肤癌或早衰和神经系统症状在内的复杂综合征。介体是一种重要的、保守的多亚基共激活物复合体。在人类中，与介质突变相关的神经发育疾病被重新归类为介质病变。最近在转录和TCR缺陷患者中发现了新的中介体变异。然而，关于转录和NER缺乏相关的复杂疾病的机制，许多问题仍未得到解答。由于其强大的遗传和基因组工具，酿酒酵母提供了一个独特的机会来揭示真核生物的基本机制。我们的工作有助于理解中介体的转录功能。此外，我们通过Rad2（人类XP/ cs相关XPG的酵母同源物）将转录和NER连接起来，发现了它的新作用。利用酵母，我们转置了与cs样症状相关的病理介质突变，并表明它们导致生长和紫外线敏感性表型，以及与TCR成分的遗传相互作用。我们正在描述它们对Pol II和Rad2的物理相互作用、转录和DNA修复的影响。转录也影响突变和DNA修复防止负责衰老和疾病的突变。然而，与转录和DNA修复相关的诱变机制仍有待充分了解。最近，我们开发了一种基于微流体的创新系统，结合高通量测序，用于酵母的突变积累。我们转置了XP、CS或ttd相关突变，并利用我们基于微流体和报告基因的方法结合诱变剂治疗，分析了它们对诱变的影响。总之，我们提出酵母模型如何为我们理解与转录和NER缺陷相关的复杂人类疾病起源的分子机制提供重要见解。philip - kjell Ficht1, Anna staffel1, Wilhelm Sponholz1, rdiger Panzer1, Anneke Lemken1, Nataliya didonat2, Joseph porrman2, Mensuda Hasanhodzic3, Ales Maver4, Tasja Scholz5, Maja Hempel5, Oleksandra Kuzmich6, Steffen emmer1， Lars boeckmann 11德国Rostock大学医学中心皮肤科和性疾病诊所2德国Technische Carl Gustav Carus大学医院临床遗传学研究所Universität德累斯顿3内分泌科，波斯尼亚和黑塞哥维那图兹拉大学临床中心4斯洛文尼亚联合大学卢伯雅那医学遗传学临床研究所孟德尔基因组学中心5德国汉堡-埃本多夫大学医学中心人类遗传学研究所6德国亚琛莱布尼茨互动材料研究所（XP）是一种常染色体隐性遗传病，其特征是光敏性增加、光化性皮肤损伤、神经系统异常，皮肤癌和粘膜癌的风险增加。这种情况是由编码核苷酸切除修复（NER）途径成分的基因缺陷引起的。在这项研究中，对疑似XP临床诊断或XP相关基因突变的患者进行了遗传和功能分析。对于遗传原因未知的患者，进行DNA测序以确定潜在的遗传缺陷。此外，对患者细胞进行功能分析，以评估其在UV-C照射后的修复能力和存活率。外显子组或Sanger测序显示，2例患者的ERCC2 （XPD）有相同的复合杂合子突变，1例患者的DDB2有纯合错义变异（XPE）， 1例患者的XPA有纯合单核苷酸变异，1例患者的XPC有纯合突变。目前正在对另外两名患者的DNA进行测序。XPA或XPC纯合变异者双亲中有一方存在杂合变异体。患者来源的成纤维细胞暴露于UV-C照射下，与野生型细胞相比，来自ERCC2或DDB2基因改变患者的细胞的UV-C后存活率没有降低，XPC的UV-C后存活率略有降低，XPA基因改变的细胞的UV-C后存活率没有降低。宿主细胞再激活试验（HCR）的初步结果表明，DDB2缺陷细胞的DNA修复能力降低可以通过转染野生型DDB2来补偿。在ERCC2发生改变的细胞中没有观察到代偿。对ERCC2复合杂合突变患者的毛发进行分析，在偏光显微镜下既没有发现半胱氨酸含量降低，也没有发现毛硫营养不良（TTD）患者的典型虎尾模式。总的来说，这项正在进行的研究表征了7名具有不同临床症状的患者的基因型和表型，并将它们联系起来。Lars Boeckmann1, Philipp Ficht1, Anna staffel1, r<s:1> diger Panzer1， Steffen emmert11德国Rostock大学医学中心皮肤性病学临床与政策中心[j] .核苷酸切除修复（NER）对于紫外线（UV）诱导的DNA损伤，如环丁烷嘧啶二聚体（CPDs）和6,4-嘧啶-嘧啶二聚体（6,4- pps）的修复至关重要。NER基因的改变可导致NER缺陷综合征。主要的ner缺陷综合征包括着色性干皮病（XP）， Cockayne综合征（CS）和毛硫营养不良（TTD）。来自德国的XP-C患者的临床和分子遗传学评估显示没有太阳敏感症状和神经症状。XP诊断的平均年龄为9.4岁，首次皮肤癌的中位年龄为7岁。我们发现了五个新的突变，包括一个氨基酸缺失(c.2538_2540delATC；p.p ile812del)导致修复缺陷，但没有XPC消息衰减。对xpg缺陷患者的评估显示，突变的类型和位置决定了临床表型。我们发现了3个错义突变，并通过分子手段表明，这些错义突变在XPG蛋白的i区破坏了修复和转录，并延迟了其他XP蛋白在紫外线光损伤后的募集及其再分配。患者表现为XP/CS复合表型。我们还发现了两个XPG和XPF剪接变体，它们在NER中具有残留的修复能力。几乎所有的变异都是严重的c端截断，缺乏重要的蛋白质相互作用结构域。有趣的是，XPF-202仅在前12个氨基酸上与XPF-003不同，完全没有修复能力，这表明该区域在DNA修复过程中发挥了重要作用。德国xpd缺陷患者表现为XP表型，与已建立的XP致病突变一致(c.2079G> a, p.R683Q；c.2078G> T, p.R683W;c.1833G> T, p.R601L;c.1878G> C, p.R616P;c.1878G> p.R616Q)。一名TTD患者为已知的TTD致病突变p.R722W （c.2195C&gt；T）纯合。2例患者为复合杂合的TTD突变（C . 366g > a, p.R112H）和p.D681H （C . 2072g &gt；C）氨基酸交换，但表现出不同的TTD和XP/CS复合表型。有趣的是，XP/CS患者的细胞表现出减少但可检测的突变XPD蛋白表达，而TTD患者的细胞几乎检测不到XPD表达。进一步的基因型-表型研究可以在欧洲罕见病参考网络（ERN-Skin）中进行。Francesca Brevi1, Arjan Theil2, Alan lehman3, Sebastian Iben4， Donata Orioli1和Elena bott1 11意大利帕维亚遗传分子研究所（IGM） CNR 2荷兰鹿特丹伊拉斯谟大学医学中心伊拉斯谟医学中心分子遗传学部3英国法尔默郡布莱顿苏塞克斯大学基因组损伤与稳定性中心4德国乌尔姆大学皮肤病学与过敏性疾病部TTD是一种以皮肤为特征的多系统疾病。神经和生长异常。光敏性的存在定义了TTD的两种主要形式-光敏（PS）和非光敏（NPS）形式。多种基因的突变与这种疾病有关。它们包括3个编码转录/DNA修复因子TFIIH不同亚基的PS-TTD相关基因，以及7个编码转录因子IIE -TFIIEβ、剪接因子TTDN1和RNF113A的β亚基的NPS-TTD相关基因，以及4个参与翻译的氨基酰基trna合成酶。所有这些与TTD相关的因素都参与了基因表达，从而提出了TTD作为一种基因表达综合征的概念。已经证明，ttd引起的TFIIH亚基或TFIIEβ突变以及TTDN1和RNF113A的敲除/敲低会影响RNA聚合酶i的转录。因此，核糖体生物发生受到伴随的易出错翻译和蛋白质稳态丧失的影响。现在，利用我们最近发现的甲硫基、苏硫基或丙烯基tRNA合成酶突变的TTD病例，我们研究了tRNA合成酶缺陷TTD病例的翻译质量。通过使用基于荧光素酶的分析，我们发现所有测试的TTD细胞的翻译错误率都很高，表明翻译不忠。此外，在单个特定氨基酸浓度升高的情况下，存活测定表明tRNA充电的准确性受损。这些改变伴随着错误折叠蛋白质的积累，表明蛋白质平衡的丧失。总的来说，翻译不忠和蛋白质平衡丧失似乎是不同形式TTD的共同潜在病理机制，可能导致患者发育受损和神经退行性变。Jordana mccloone 1,2, Kyra Webb2, Kathy Tucker3, Antoinette Anazodo2, Denise Wilson5, Linda martin1,4,51悉尼新南威尔士大学，临床医学院2儿童癌症中心，悉尼儿童医院3遗传癌症中心，悉尼儿童医院，unsw4皮肤科，悉尼儿童医院5澳大利亚黑色素瘤研究所背景：在澳大利亚，没有专门的诊断或管理服务，用于着色性干皮病（XP）患者。目的：了解有孩子被诊断为XP的家庭的支持性护理需求。方法：邀请澳大利亚一名XP儿童的父母和照顾者，以及5-18岁无智力障碍的XP儿童参与。参与者是通过临床网络和社交媒体患者支持团体确定的。通过面对面或通过Zoom进行半结构化访谈，重点关注诊断过程、当前护理、首选护理模式、心理社会影响和信息需求。访谈资料用QSR NVivo Pro逐字转录并逐行编码。采用归纳主题分析法组织节点和主题。结果：访问了8名成人护理人员和3名XP儿童，其中1个XP- a家庭，1个XP- c家庭，2个XP- d家庭。7个家庭中有5个参与了调查。大多数家庭在诊断前有很长时间的延误，因为误解了症状。基因检测的等待时间为6-12个月。所有家庭都报告了高度未满足的信息需求，包括如何防晒、预后和管理。家长们报告了未满足的心理需求，包括内疚、恐惧、悲伤、孤立和过度警惕。适应和防晒要求是昂贵的。患者的首选护理模式是一个多学科团队，包括皮肤病学，眼科，神经病学和相关健康。强调护理的连续性。结论：发展全面的临床服务，以解决澳大利亚XP患者的诊断、预防、监测、治疗和支持性护理需求是迫切的。Riccardo Paolini1, Yvette Walker2， T. Xiong1, Konstantina Vasilakopoulou, Linda Martin3,41新南威尔士大学建筑环境学院，艺术与设计学院；2 unsw罕见疾病；3 unsw临床医学院，医学院；悉尼儿童医院澳大利亚黑色素瘤研究所。背景：对所有紫外线（UV）辐射的完全防护要求着色性干皮病（XP）患者穿着高度防护的服装，包括带遮阳板的兜帽，全套衣服和手套。市售服装的设计和测试仅用于防紫外线，但可能导致大量的太阳热量增加，导致人体热不适，实际上限制了户外活动，影响了生活质量。目的:测试对热性能的影响的太阳能控制电影的XP遮阳板(PS90 3米)。方法：采用红外热像仪（T540）测量表面温度。材料的光学性质用带有150mm积分球的紫外-可见-近红外分光光度计（Perkin Elmer的Lambda 1050+）进行表征，宽带性质（太阳、紫外、可见和近红外）用空气质量1的全球水平辐射的太阳辐照度分布计算，遵循ASTM E903。结果：普通遮阳板在250 ~ 380 nm波长范围内的紫外线透过率为零，而在380 ~ 400 nm波长范围内有一定的透光率（385 nm为0.02 ~ 400 nm为0.64），导致其总紫外线透过率为0.08，太阳透过率为0.83。使用太阳控制膜（PS90），总紫外线透过率降至0.02，太阳透过率降至0.59。添加到遮阳板上的PS90薄膜在不影响清晰视觉的情况下将可见光透过率降低0.11，并将近红外透过率降低0.45，因此几乎将太阳光谱中不可见部分的太阳热量增益减半。此外，透明薄膜显示低太阳吸收率，因此，限制表面过热。当这些组合在室外（晴空条件28.4℃，太阳辐射365 W/m2，紫外线辐射13 W/m2）进行测试时，在顶部添加PS90薄膜比平面遮阳板0.6 m/s，太阳辐射365 W/m2，紫外线辐射13 W/m2低2.9℃。结论：XP患者不易获得既紫外线安全又热安全的防护服，特别是在温暖的气候条件下。在紫外线遮阳板上加上一层现成的太阳能薄膜，使太阳的热增益减半。Vuong-Brender than1,2 and Schumacher Björn1,21衰老与疾病基因组稳定性研究所，科隆大学医学院，科隆大学医院，德国。2衰老相关疾病细胞应激反应卓越集群（CECAD），科隆大学科隆分子医学中心（CMMC），德国科隆。由于其简单的身体结构，秀丽隐杆线虫可以用于研究细胞和有机体水平上的DNA损伤反应。我们使用秀丽隐杆线虫XPC -1突变体（哺乳动物DNA损伤传感器XPC的同源物）来了解全球基因组核苷酸切除修复（GG-NER）途径缺陷突变体的替代修复。XPC-1在秀丽隐杆线虫种系中强烈表达。当xpc-1突变体的第一个瞬间幼虫被紫外线处理时，原始生殖细胞（PGCs）在随后的幼虫生长到成年期间不能发育成种系。我们发现，内切酶基因-1的突变强烈增强了xpc-1突变体在紫外线诱导下的种系发育缺陷。这种紫外线敏感性的增加需要GEN-1及其c端区域的催化活性。我们的数据显示，GEN-1介导了xpc-1突变体对紫外线的生殖细胞阻滞，这表明当病变不能通过典型的GG-NER途径修复时，GEN-1调节了PGCs中的DNA损伤检查点。这种阻滞似乎允许另一种修复途径独立于brc-1/BRCA1和brd-1/BARD1介导的双链断裂修复，以及fcd-2/FANCD2介导的范可尼贫血途径。在随后的s期和有丝分裂中，GEN-1依赖性替代修复的缺失分别导致复制和染色体分离缺陷，这可以通过激活纺锤体组装检查点来部分修复。我们的结果指出了XP患者DNA修复的潜在重要调节因子。Teodora svilensk1, Chiara Cimmaruta2, Claudia Bogner3, Vincent Laugel4, Wolfram gronwal3, Miria Ricchetti2, York Kamenisch1*， Mark Berneburg1*1雷根斯堡大学医院皮肤科，93042德国雷根斯堡，电话：0941 944-9601,2；病理和生理衰老的分子机制，Roux大道25号巴斯德研究所，75724巴黎Cedex 15；功能基因组学研究所，功能基因组学部门，93053雷根斯堡，德国，9；电话：0941 943 50154；斯特拉斯堡大学医院，豪特皮埃尔医院神经肌肉中心，豪特皮埃尔医院，moli<e:1>大道，67000斯特拉斯堡，法国*：通讯作者，邮编：科凯恩综合征（Cockayne syndrome， CS）是一种罕见的遗传性疾病，具有进行性严重神经缺陷和紫外线敏感等早衰症状，迄今尚无治疗方法。研究与衰老过程或应激源相关的代谢变化，对于增加对导致细胞和生物体衰老的复杂过程的认识是必要的。先前的研究表明，人体皮肤细胞暴露于UVA辐射或活性氧（ROS）等应激源会导致细胞代谢，特别是葡萄糖代谢发生显著变化。高水平的UVA诱导葡萄糖和丙酮酸的消耗可能参与了这些暴露于UVA的细胞的ROS解毒策略。除此之外，已知CS细胞比WT细胞表现出更高水平的细胞ROS损伤。在这个项目中，我们研究了应激源（ROS）对来自CS伴早衰综合征患者或健康个体（WT）的原代人皮肤成纤维细胞代谢和耗氧量的影响。对这些细胞进行重复低剂量UVA照射（诱导ROS），随后使用Clark型电极测量细胞耗氧量，并使用核磁共振波谱（NMR）测量细胞上清液的代谢变化。UVA照射诱导细胞上清液中许多代谢物（葡萄糖、乳酸、丙酮酸、乙酸、谷氨酰胺、谷氨酸、胆碱、丙氨酸、甜菜碱）发生显著变化。与WT细胞相似，UVA处理后，CS细胞葡萄糖和丙酮酸消耗增加，乳酸和丙氨酸分泌增加。有趣的是，在没有外部应激源（UVA照射）的情况下，WT细胞和CS细胞之间的代谢差异已经存在，而且这些差异在UVA治疗后会增加。关于细胞呼吸，在没有外界刺激的情况下，CS和WT细胞之间的耗氧量差异是可见的。WT细胞的耗氧率高于CS细胞。应激源（UVA辐照）的应用增强了WT细胞和CS细胞之间的这些差异。本研究揭示了早衰症状患者CS细胞与WT细胞在代谢和呼吸方面的差异。众所周知，在特定条件下，细胞呼吸过程可以产生高水平的活性氧。因此，可以推测，CS细胞试图利用与糖酵解相关的代解性ROS解毒策略（比WT细胞消耗更高的葡萄糖和丙酮酸），以减少呼吸过程中ROS的产生（比WT细胞呼吸速率低）。简介：皮肤恶性肿瘤是色素性干皮病患者过早死亡的主要原因。皮肤鳞状细胞癌（cSCC）是我们所见的XP患者中最常见的皮肤癌。由于其DNA功能受损，迅速的局部和远处转移使手术治疗变得困难。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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Journal Der Deutschen Dermatologischen Gesellschaft 医学-皮肤病学

CiteScore

3.50

自引率

25.00%

发文量

406

审稿时长

1 months

期刊介绍： The JDDG publishes scientific papers from a wide range of disciplines, such as dermatovenereology, allergology, phlebology, dermatosurgery, dermatooncology, and dermatohistopathology. Also in JDDG: information on medical training, continuing education, a calendar of events, book reviews and society announcements. Papers can be submitted in German or English language. In the print version, all articles are published in German. In the online version, all key articles are published in English.