Experimental hematology最新文献

{"title":"2007 – INFORMING THERAPEUTIC APPROACHES FOR P53 DEFECTIVE BLOOD CANCERS","authors":"Gemma Kelly ,&nbsp;Sarah Diepstraten ,&nbsp;Yin Yuan ,&nbsp;John (Eddie) La Marca ,&nbsp;Savannah Young ,&nbsp;Catherine Chang ,&nbsp;Lauren Whelan ,&nbsp;Aisling Ross ,&nbsp;Karla Fischer ,&nbsp;Giovanna Pomilio ,&nbsp;Rhiannon Morris ,&nbsp;Angela Georgiou ,&nbsp;Veronique Litalien ,&nbsp;Fiona Brown ,&nbsp;Andrew Roberts ,&nbsp;Andreas Strasser ,&nbsp;Andrew Wei","doi":"10.1016/j.exphem.2024.104564","DOIUrl":"10.1016/j.exphem.2024.104564","url":null,"abstract":"<div><p>Mutations in the tumour suppressor TP53 are common in many cancers, including aggressive blood cancers, and confer poor responses to chemotherapy. Newer BH3-mimetic drugs, such as the BCL-2 inhibitor Venetoclax, were postulated to be effective therapy for TP53 mutant blood cancers since these drugs initiate apoptosis downstream of TP53 and therefore should function agnostic of TP53 status. However recent data from our lab and others indicate wild-type TP53 is required for maximal cancer cell killing by BH3-mimetic drugs.</p><p>Using pre-clinical models of several blood cancers and CRISPR/Cas9 approaches, we interrogated the role of TP53 in the apoptotic response to BH3-mimetic drugs. We found that TP53 is not needed for BH3-mimetics to induce apoptosis via mitochondrial outer membrane permeabilization (MOMP). However, TP53 becomes activated downstream of MOMP, leading to induction of the pro-apoptotic BH3-only proteins and a second wave of apoptosis that reinforces killing of the cancer cells. Blood cancers with mutant TP53 cannot induce this enforcing wave of apoptosis and are therefore more likely to survive and contribute to relapse.</p><p>Through these analyses we identified an alternative complementary pathway to activate apoptosis using STING agonist drugs. We found that STING agonists could induce BH3-only protein expression in a TP53-independent manner, boosting the pro-apoptotic signal. Combining STING agonists with BH3-mimetic drugs led to highly effective killing of mouse B cell lymphomas, human NK/T cell lymphomas and patient-derived Acute Myeloid Leukemia blasts, even those that were mutated for TP53. Since STING agonists are already in clinical trials to induce anti-tumour immunity, we anticipate repurposing them to boost apoptosis alongside BH3-mimetic drugs in clinical trials for blood cancer patients would be effective and relatively straight forward.</p></div>","PeriodicalId":12202,"journal":{"name":"Experimental hematology","volume":"137 ","pages":"Article 104564"},"PeriodicalIF":2.5,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0301472X24004235/pdfft?md5=b3b4f58f4ac1812f14df07970f268378&pid=1-s2.0-S0301472X24004235-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142087174","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"2011 – SUBCLONAL MUTATIONS ALTER CORE SIGNALLING NODES AND DRUG RESPONSES IN PAEDIATRIC ACUTE LYMPHOBLASTIC LEUKAEMIA","authors":"Teresa Sadras ,&nbsp;Lauren Brown ,&nbsp;Paul Ekert ,&nbsp;Edwin Hawkins ,&nbsp;Rob Salomon ,&nbsp;Kaitlyn Kew","doi":"10.1016/j.exphem.2024.104568","DOIUrl":"10.1016/j.exphem.2024.104568","url":null,"abstract":"<div><p>Aberrant expression of cytokine receptor-like factor 2 (CRLF2) occurs in 5–15% of B-cell acute lymphoblastic leukaemia (B-ALL) and is associated with poor outcomes.</p><p>Approximately 50% of CRLF2+ B-ALLs also harbor activating mutations in JAK2. Coexpression of CRLF2 and mutant JAK2 results in constitutive STAT5 activation, and factor-independent transformation of B cell progenitors. The current consensus is that JAK/STAT activation is the hallmark of CRLF2 B-ALL, however JAK2 inhibitors such as Ruxolitinib have shown limited efficacy in this leukemia. We have shown that some CRLF2+ B-ALLs lacking JAK2 mutations instead harbor activating mutations in the RAS-ERK pathway (e.g. KRAS-G12D). Using single-cell sequencing of matched diagnosis and relapse patient samples, we show that in patients with both STAT and ERK activating lesions, these mutations are present in competing clones which fluctuate during disease progression. However, it remains unknown how subclonal mutations alter the signalling properties and drug responses of CRLF2+ leukemias. To investigate this, we established murine models expressing the human CRLF2 receptor complex and common JAK2 and RAS pathway mutations. Using phospho-proteomics, and high throughput drug screening we show for the first time that the combination of CRLF2 with RAS mutations activates distinct signalling networks, compared to CRLF2 combined with mutant JAK2, and that this drives unique drug dependencies that can be therapeutically leveraged. To investigate subclonal dynamics in vivo, we use advanced imaging approaches to visualise how distinct sublones engage bone marrow niche structures during development, and under pressure of chemotherapy. This work reveals novel insights into the importance of subclonal mutations on the biology of CRLF2+ B-ALL.</p></div>","PeriodicalId":12202,"journal":{"name":"Experimental hematology","volume":"137 ","pages":"Article 104568"},"PeriodicalIF":2.5,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0301472X24004272/pdfft?md5=9177018801f94e59a8cfc25151231fdd&pid=1-s2.0-S0301472X24004272-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142087178","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"3040 – RUNX1 CIS-REGULATION AND EFFECTOR FUNCTION DURING HUMAN ENDOTHELIAL-TO-HAEMATOPOIETIC TRANSITION","authors":"Alessandro Cavallo ,&nbsp;Giorgio Anselmi ,&nbsp;Thomas A. Milne ,&nbsp;Marella F.T.R. de Bruijn","doi":"10.1016/j.exphem.2024.104362","DOIUrl":"10.1016/j.exphem.2024.104362","url":null,"abstract":"<div><p>The first haematopoietic stem and progenitor cells (HSPCs) in the embryo arise through a process known as endothelial-to-haematopoietic transition (EHT). In a subset of endothelial cells referred to as haemogenic endothelium (HE), the endothelial transcriptional programme is gradually replaced by a haematopoietic one, promoting haematopoietic commitment and ultimately EHT. This process is critically dependent on the transcription factor RUNX1. There is currently limited knowledge on the transcriptional regulation and downstream function of RUNX1 during human EHT. Here, using an in vitro human induced pluripotent stem cell (hiPSC) differentiation model, we identified five candidate EHT RUNX1 enhancers, characterised by H3K27ac and open chromatin, one of which is only accessible in HE and four are accessible in haematopoietic cells. Through gene regulatory network (GRN) analysis, performed on joint single-cell chromatin accessibility and gene expression profiling data, we identified a set of candidate upstream RUNX1 activators and repressors. These included known RUNX1 regulators (e.g. GATA2, MEIS1, EPAS1) as well as potentially novel ones. To identify the downstream target genes of RUNX1, we profiled RUNX1-binding sites genome-wide in hiPSC-derived HE, where most of these sites were not acetylated and were associated with endothelial genes, suggesting RUNX1 might directly repress the endothelial programme. Together, our data are expected to improve our understanding of the regulatory mechanisms underlying human EHT.</p></div>","PeriodicalId":12202,"journal":{"name":"Experimental hematology","volume":"137 ","pages":"Article 104362"},"PeriodicalIF":2.5,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0301472X24002212/pdfft?md5=c05f44c38363ddf031b78f144f5ef734&pid=1-s2.0-S0301472X24002212-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142087207","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"3035 – INTERFERON ALPHA THERAPY ATTENUATES LEUKAEMIC TRANSFORMATION IN JAK2V617F-DRIVEN MPN WITH TRP53-LOSS","authors":"Megan Bywater ,&nbsp;Ranran Zhang ,&nbsp;Julian Grabek ,&nbsp;Rohit Halder ,&nbsp;Yashaswini Janardhanan ,&nbsp;Leanne Cooper ,&nbsp;Emily Cooper ,&nbsp;David Ross ,&nbsp;Jasmin Straube ,&nbsp;Steven Lane","doi":"10.1016/j.exphem.2024.104357","DOIUrl":"10.1016/j.exphem.2024.104357","url":null,"abstract":"<div><p>Driver mutations in classical myeloproliferative neoplasms (MPNs) (eg. JAK2V617F ) must be initiated and maintained in the haematopoietic stem cell (HSC) pool. Leukaemic transformation to post-MPN AML is characterised by additional genetic lesions and mutations in TP53 are predictive of poor outcomes. Interferon alpha (IFNa) can drive HSC cell cycle entry preferentially in Jak2V617F HSCs resulting in reduced self-renewal capacity. Clinically, IFNa therapy can achieve long-term reductions in JAK2V617F allelic burden. However, the impact of additional mutations on IFNa responses in MPN and transformation to AML remains unclear.</p><p>We have generated a single cell RNA sequencing pipeline to monitor the genetic and transcriptional heterogeneity of the HSPC compartment of MPN patients during AML transformation. Transformation is linked with a loss of HSPC hierarchy and devolution to a dominant multipotent progenitor (MPP) state. Using these data to inform parallel murine studies, we demonstrate that haematopoietic expression of Jak2V617F with Trp53-loss is sufficient to drive a fully penetrant leukemia preceded by a distinct MPN disease phase in mice. The resulting AML exhibits a dominant lineage-biased MPP that has leukaemia initiating activity in secondary recipients.</p><p>IFNa is still able to induce haematological responses in Jak2V617F MPN with Trp53-loss. However, Trp53-loss also provides a selective advantage for HSCs in the context of chronic exposure to IFNa. Surprisingly, the effects of IFNa on reduced stem cell function are retained in the absence of p53 and chronic administration of IFNa is sufficient to delay leukaemic transformation. Furthermore, IFNa therapy is also effective at preventing disease progression in an established Jak2V617F AML with Trp53-loss. These findings have important implications for the treatment of MPN with TP53 mutations.</p></div>","PeriodicalId":12202,"journal":{"name":"Experimental hematology","volume":"137 ","pages":"Article 104357"},"PeriodicalIF":2.5,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0301472X24002169/pdfft?md5=abde782a92ee09d24b00546d5a733c45&pid=1-s2.0-S0301472X24002169-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142087208","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"2018 – TET2-MUTANT CLONAL HEMATOPOIESIS REPROGRAMS THE TUMOUR MICROENVIRONMENT TO PROMOTE IMMUNOTHERAPY RESPONSE","authors":"Robert Vanner ,&nbsp;Suraj Bansal ,&nbsp;Marco Buttigeig ,&nbsp;Andy Zeng ,&nbsp;Yitong Yang ,&nbsp;Darryl Chan ,&nbsp;Vincent Rondeau ,&nbsp;Carsten Muller-Tidow ,&nbsp;Michael Rauh ,&nbsp;Steven Chan ,&nbsp;Andreas Trumpp ,&nbsp;John Dick","doi":"10.1016/j.exphem.2024.104575","DOIUrl":"10.1016/j.exphem.2024.104575","url":null,"abstract":"<div><p>Clonal hematopoiesis is common in solid tumour patients, who frequently have loss of function mutations in TET2. TET2 restricts innate and adaptive immunity, so we hypothesized that TET2-mutant clonal hematopoiesis (TET2-CH) is associated with immunotherapy response. To test this hypothesis, syngeneic colorectal cancer-bearing mice with Tet2-heterozygous null (Tet2-het) or wild type hematopoiesis were treated with anti-PD-1 immunotherapy. Treatment responses were greater and tumors were smaller in Tet2-het mice. The Tet2-effect required phagocytes, CD4, and CD8 T cells, but not NK cells. scRNA-seq revealed how Tet2-mutations reshape the tumor-infiltrating cell (TIL) landscape with immunotherapy by inducing anti-tumour states and restricting pro-tumour cell states. Tet2-mutant monocytes upregulated T cell costimulatory genesets and we found enhanced communication between Tet2-het antigen presenting and T cells. Combined sc-genotyping and RNA-seq of primary TET2-CH patient leukocytes showed that, like mouse TILs, human TET2-mutant monocytes upregulated costimulatory and inflammatory programs associated with immunotherapy response. TET2-mutant CD8 T cells were rare but strikingly enriched for memory programs and TCR signaling, yet suppressed an exhaustion signature. Melanoma patient RNA-seq showed TET2-CH+ tumours are enriched for antigen presentation/costimulation and T cell memory versus exhaustion. TET2-CH+ melanomas also had increased immune infiltrate, T cells and dendritic cells, and re-analysis of 200 immunotherapy-treated melanoma patients showed those with TET2-CH were 6-fold more likely to benefit from immunotherapy. Therefore, across mouse tumours, human leukocytes and tumours, somatic TET2-mutations activate transcriptional programs in myeloid and T cells associated with anti-tumour immunity, which correlate with enhanced immunotherapy response in melanoma.</p></div>","PeriodicalId":12202,"journal":{"name":"Experimental hematology","volume":"137 ","pages":"Article 104575"},"PeriodicalIF":2.5,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0301472X2400434X/pdfft?md5=9c9a370a11fc6a3bb19cb7af06f0a418&pid=1-s2.0-S0301472X2400434X-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142087345","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"3029 – MITOCHONDRIAL REGULATION OF CELL FATE THROUGH BIOGENESIS OF EXTRACELLULAR VESICLES IN HSC","authors":"Massimo Bonora ,&nbsp;Claudia Morganti ,&nbsp;Nick Van Gastel ,&nbsp;Keisuke Ito","doi":"10.1016/j.exphem.2024.104351","DOIUrl":"10.1016/j.exphem.2024.104351","url":null,"abstract":"<div><p>Mitochondrial fatty acid oxidation (FAO) is essential for hematopoietic stem cell (HSC) self-renewal, however the mechanism by which mitochondrial metabolism controls HSC fate remains unknown. Here we show that within the hematopoietic lineage, HSCs have the largest mitochondrial NADPH pools, which are required for proper HSC cell fate and homeostasis. Bioinformatic analysis of the HSC transcriptome, biochemical assays, and genetic inactivation of FAO all indicate that FAO-generated NADPH fuels cholesterol synthesis in HSCs. Interference with FAO disturbs the segregation of mitochondrial NADPH toward corresponding daughter cells upon single HSC division. Importantly, we have found that the FAO-NADPH-cholesterol axis drives extracellular vesicle (EV) biogenesis and release in HSCs, while inhibition of EV signaling impairs HSC self-renewal. These data reveal the existence of a mitochondrial NADPH-cholesterol axis for EV biogenesis that is required for hematopoietic homeostasis and highlight the non-stochastic nature of HSC fate determination.</p></div>","PeriodicalId":12202,"journal":{"name":"Experimental hematology","volume":"137 ","pages":"Article 104351"},"PeriodicalIF":2.5,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0301472X24002108/pdfft?md5=29d1fd678acae671829a8056f3aa7db5&pid=1-s2.0-S0301472X24002108-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142087369","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"1027 –","authors":"Mitch Weiss","doi":"10.1016/j.exphem.2024.104328","DOIUrl":"10.1016/j.exphem.2024.104328","url":null,"abstract":"<div><p>No Abstract Submitted</p></div>","PeriodicalId":12202,"journal":{"name":"Experimental hematology","volume":"137 ","pages":"Article 104328"},"PeriodicalIF":2.5,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0301472X24001875/pdfft?md5=104bbe614d4f1a8a6b63103e336b083b&pid=1-s2.0-S0301472X24001875-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142087375","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"3012 – DEEPLY QUIESCENT HEMATOPOIETIC STEM CELLS MAINTAIN FUNCTION BY GPRASP2-MEDIATED CELL-SURFACE RECEPTOR DEGRADATION","authors":"Alanna Van Huizen ,&nbsp;Zakiya Kelley ,&nbsp;Emilia Kooienga ,&nbsp;Dirk Loeffler ,&nbsp;Preeti Dabas ,&nbsp;Rashid Mehmood ,&nbsp;Lance Palmer ,&nbsp;Antonio Morales-Hernandez ,&nbsp;Shannon McKinney-Freeman","doi":"10.1016/j.exphem.2024.104300","DOIUrl":"10.1016/j.exphem.2024.104300","url":null,"abstract":"<div><p>The hematopoietic stem cell (HSC) pool is highly heterogeneous, including a subset of HSCs that rarely contribute to homeostatic hematopoiesis but can be recruited to cycle under stress. Such deeply quiescent HSCs with a low division history perform best when transplanted. However, few tools exist to isolate and interrogate mechanisms regulating the balance between quiescence and activation required to maintain HSC integrity. We recently reported Gprasp2 (G-protein Coupled Receptor (GPCR)-associated Sorting Protein 2) as an HSC regulator during transplantation. Involved in post-endosomal sorting to the lysosome, GPRASP2 is HSC-enriched and heterogeneously expressed in single HSCs. Further, low Gprasp2 (Gprasp2low) expressing HSCs are transcriptionally programmed for lineage-specific differentiation and cell cycling relative to Gprasp2high HSCs. Using our Gprasp2-reporter mouse, we serially transplanted Gprasp2high/low HSCs and found that Gprasp2high HSCs have slower repopulation kinetics with balanced reconstitution and increased, prolonged blood output compared to Gprasp2low HSCs. Single Gprasp2high/low HSC transplantation confirms Gprasp2high clones with delayed yet robust, balanced blood output. Proteomic profiling reveals Gprasp2high HSCs are programmed for quiescence, confirmed by assaying in vivo cycling kinetics. Prospectively, elevated GPRASP2 maintains HSC quiescence by limiting GPCR cell-surface availability via targeted lysosomal degradation. Assessed GPCR candidates show decreased cell surface expression on Gprasp2high HSCs and increased expression on Gprasp2low HSCs. Gprasp2 is hierarchically restricted and heterogeneously expressed in human HSCs, and human Gprasp2high/low HSCs are transcriptionally distinct. Cumulatively, GPRASP2 marks a subset of quiescent, durable repopulating HSCs that preserve function by limiting GPCR cell-surface availability.</p></div>","PeriodicalId":12202,"journal":{"name":"Experimental hematology","volume":"137 ","pages":"Article 104300"},"PeriodicalIF":2.5,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0301472X24001590/pdfft?md5=f65d633b87aa446459bea90f6bfc0437&pid=1-s2.0-S0301472X24001590-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142087383","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"IFC Editorial Board","authors":"","doi":"10.1016/S0301-472X(24)00463-6","DOIUrl":"10.1016/S0301-472X(24)00463-6","url":null,"abstract":"","PeriodicalId":12202,"journal":{"name":"Experimental hematology","volume":"137 ","pages":"Article 104604"},"PeriodicalIF":2.5,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0301472X24004636/pdfft?md5=8078fe024a8ef80403232efe55c331d2&pid=1-s2.0-S0301472X24004636-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142086820","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"3025 – MITOFUSIN 2 AGONISTS REGULATES MTOR SIGNALING TO SUPPORT HUMAN HSC EXPANSION IN VITRO","authors":"Alyssa Biondo ,&nbsp;Gabriela Candelaria ,&nbsp;Daniel Jin ,&nbsp;Emily Lin ,&nbsp;Zhaolun Liang ,&nbsp;Katherine Leong ,&nbsp;Daniel McLaughin ,&nbsp;Hans-Willem Snoeck ,&nbsp;Larry Luchsinger","doi":"10.1016/j.exphem.2024.104347","DOIUrl":"10.1016/j.exphem.2024.104347","url":null,"abstract":"<div><p>Using cord blood units (CBU) for hematopoietic stem cell transplants (HSCT) improves match compatibility and reduces graft versus host disease. Limited cell numbers hinder widespread adult use. In vitro expansion overcomes dose limits, but techniques for long-term HSC expansion are underdeveloped, prompting the need for novel molecular targets. Studies in mice have implicated Mitofusin 2 (MFN2) activity as necessary to maintain potent HSCs in vitro. Recent studies have described efficacious small molecule agonists of MFN2 fusion. Thus, we hypothesized that MFN2 agonist treatment during short-term UCB cell expansion could enhance HSC repopulating function. Our study revealed phenotypic HSCs expanded with MFN2 agonists displayed a highly significant increase in long-term chimerism for both primary and secondary xenografts of MFN2 agonist HSC culture recipients compared to vehicle, revealing MFN2 fusion as necessary for human HSC function. MFN2 agonist-treated HSCs displayed upregulation of genes associated with ribosome, stress granules, and autophagy are hallmarks of HSC maintenance mechanisms. HSC cultures exposed to MFN2 agonist exhibited decreased protein translation by OP-Puro assay, heightened lysosome count and acidification using lysotracker dyes, and increased LC3B puncta, indicating heightened autophagy. Network analysis of DGEs suggested upstream regulation via MTOR signaling. HeLa cells treated with MFN2 agonist or rapamycin displayed increased TFEB nuclear levels (lysosomal biogenesis master regulator), indicating enhanced autophagy. Additionally, reduced S6 phosphorylation, a downstream target of MTOR, and direct MFN2-MTOR interaction indicated by immunoprecipitation assays, suggests MFN2 inhibits MTOR signaling. Overall, our findings elucidate a novel mechanism whereby MTOR inhibition via MFN2 induces catabolic programs to maintain HSC function in vitro.</p></div>","PeriodicalId":12202,"journal":{"name":"Experimental hematology","volume":"137 ","pages":"Article 104347"},"PeriodicalIF":2.5,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0301472X24002066/pdfft?md5=3499a90e9888416aaa36ca9e08182628&pid=1-s2.0-S0301472X24002066-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142087019","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}