Mutation Research-Fundamental and Molecular Mechanisms of Mutagenesis最新文献

{"title":"The duration of exposure to 50 Hz magnetic fields: Influence on circadian genes and DNA damage responses in murine hematopoietic FDC-P1 cells","authors":"Ehab Mustafa ,&nbsp;Jukka Luukkonen ,&nbsp;Jenny Makkonen ,&nbsp;Jonne Naarala","doi":"10.1016/j.mrfmmm.2021.111756","DOIUrl":"10.1016/j.mrfmmm.2021.111756","url":null,"abstract":"<div><p>We investigated the effects of 50 Hz extremely low-frequency magnetic fields (MFs) on gene expression related to the circadian rhythm or DNA damage signaling and whether these fields modify DNA damage repair rate after bleomycin treatment. Murine FDC-P1 hematopoietic cells were exposed for different durations (15 min, 2 h, 12 h, and 24 h) to either 200 μT MFs or sham-exposures. Cells were then collected for comet assay or real-time PCR to determine immediate DNA damage level and circadian rhythm gene expression, respectively. To assess DNA-damage signaling and DNA repair rate, the cells were subsequently treated with 20 μg/mL bleomycin for 1 h and then either assayed immediately or allowed to repair their DNA for 1 or 2 h. We found that circadian rhythm-related genes were upregulated after 12 h of MF exposure and downregulated after 24 h of MF exposure, but none of the affected genes were core genes controlling the circadian rhythm. In addition, we found that the repair rate for bleomycin-induced damage was only decreased after MF exposure for 24 h. In conclusion, our findings suggest that the effects of MFs are duration-dependent; they were observed predominantly after long exposures.</p></div>","PeriodicalId":49790,"journal":{"name":"Mutation Research-Fundamental and Molecular Mechanisms of Mutagenesis","volume":"823 ","pages":"Article 111756"},"PeriodicalIF":2.3,"publicationDate":"2021-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.mrfmmm.2021.111756","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39253043","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":"The dose-, LET-, and gene-dependent patterns of DNA changes underlying the point mutations in spermatozoa of Drosophila melanogaster. I. Autosomal gene black","authors":"I.D. Alexandrov,&nbsp;M.V. Alexandrova","doi":"10.1016/j.mrfmmm.2021.111755","DOIUrl":"10.1016/j.mrfmmm.2021.111755","url":null,"abstract":"<div><p>Sequence analysis of 7 spontaneous, 27 γ-ray- and 20 neutron/neutron+γ-ray-induced <em>black (b)</em> point mutants was carried out. All these mutants were isolated as non-mosaic transmissible recessive visibles in the progeny of irradiated males from the wild-type high-inbred laboratory D32 strain of <em>Drosophila melanogaster</em>. Among spontaneous mutants, there were two (28.5 %) mutants with <em>copia</em> insertion in intron 1 and exon 2, three (42.8 %) with replacement of <em>b^+D32</em> paternal sequence with maternal <em>b¹</em> sequence (gene conversion), one (14.3 %) with 142-bp-long insertion in exon 2, and one (14.3 %) with a short deletion and two single-base substitutions in exon 3. Among γ-ray-induced mutants, there were 1 (3.7 %) with <em>copia</em> insertion in intron 2, 6 (22.2 %) with gene conversion, and the remaining 20 (74.1 %) mutants had 37 different small-scale DNA changes. There were 20 (54.1 %) single- or double-base substitutions, 7 (18.9 %) frameshifts (indels), 9 (24.3 %) extended deletions or insertions, and 1(2.7 %) mutant with a short insertion instead of a short deletion. Remarkably, clusters of independent small-scale changes inside the gene or within one DNA helical turn were recovered. The spectrum of DNA changes in 20 neutron/ neutron+γ-ray-induced mutants was drastically different from that induced by γ-rays in that 18 (90.0 %) mutants had the <em>b¹</em>sequence. In addition, 2 (10.0 %) with gene conversion had 600- or 19-bp-long deletion in exon 3 and 1 (5.0 %) mutant with a short insertion instead of a short deletion. Analysis of all 27 mutants with gene conversion events shows that 20 (74.1 %) had full <em>b¹</em> sequence whereas 7 others (25.9 %) contained a partial <em>b</em>¹ sequence. These data are the first experimental evidence for gene conversion in the early stages of animal embryogenesis in the first diploid cleavage nucleus after male and female pronuclei have united. The gene conversion, frameshifts (indels), and deletions between short repeats were considered as products of a relevant DNA repair pathways described in the literature. As the first step, the gametic doubling doses for phenotypic <em>black</em> point mutations and for intragenic base substitution mutations in mature sperm cells irradiated by 40 Gy of γ-rays were estimated as 5.8 and 1.2 Gy, respectively, showing that doubling dose for mutations at the molecular level is about 5 times lower than that at the phenotypic level.</p></div>","PeriodicalId":49790,"journal":{"name":"Mutation Research-Fundamental and Molecular Mechanisms of Mutagenesis","volume":"823 ","pages":"Article 111755"},"PeriodicalIF":2.3,"publicationDate":"2021-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.mrfmmm.2021.111755","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39078100","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Identification and characterization of inheritable structural variations induced by ion beam radiations in rice","authors":"Yunchao Zheng ,&nbsp;Shan Li ,&nbsp;Jianzhong Huang ,&nbsp;Haowei Fu ,&nbsp;Libin Zhou ,&nbsp;Yoshiya Furusawa ,&nbsp;Qingyao Shu","doi":"10.1016/j.mrfmmm.2021.111757","DOIUrl":"10.1016/j.mrfmmm.2021.111757","url":null,"abstract":"<div><p>High energy ion beams are effective physical mutagens for mutation induction in plants. Due to their high linear energy transfer (LET) property, they are known to generate single nucleotide variations (SNVs) and insertion/deletions (InDels, &lt;50 bp) as well as structural variations (SVs). However, due to the technical difficulties to identify SVs, studies on ion beam induced SVs by genome sequencing have so far been limited in numbers and inadequate in nature, and knowledge of SVs is scarce with regards to their characteristics. In the present study, we identified and validated SVs in six M₄ plants (designated as Ar_50, Ar_100, C_150, C_200, Ne_50 and Ne_100 according to ion beam types and irradiation doses), two each induced by argon (⁴⁰Ar¹⁸⁺), carbon (¹²C⁶⁺) and neon (²⁰Ne¹⁰⁺) ion beams and performed in depth analyses of their characteristics. In total, 22 SVs were identified and validated, consisting of 11 deletions, 1 duplication, and 4 intra-chromosomal and 6 inter-chromosomal translocations. There were several SVs larger than 1 kbp. The SVs were distributed across the whole genome with an aggregation with SNVs and InDels only in the Ne_50 mutants. An enrichment of a 11-bp wide G-rich DNA motif 'GAAGGWGGRGG' was identified around the SV breakpoints. Three mechanisms might be involved in the SV formation, i.e., the expansion of tandem repeats, transposable element insertion, and non-allelic homologous recombination. Put together, the present study provides a preliminary view of SVs induced by Ar, C and Ne ion beam radiations, and as a pilot study, it contributes to our understanding of how SVs might form after ion beam irradiation in rice.</p></div>","PeriodicalId":49790,"journal":{"name":"Mutation Research-Fundamental and Molecular Mechanisms of Mutagenesis","volume":"823 ","pages":"Article 111757"},"PeriodicalIF":2.3,"publicationDate":"2021-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.mrfmmm.2021.111757","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39194493","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Enhanced characterization of the thyA system for mutational analysis in Escherichia coli: Defining mutationally “hot” regions of the gene","authors":"Daniel Mashiach,&nbsp;Erin Mae Bacasen,&nbsp;Sunjum Singh,&nbsp;Timothy Kao,&nbsp;Lekha Yaramada,&nbsp;Daniel Mishail,&nbsp;Summer Singh,&nbsp;Jeffrey H. Miller","doi":"10.1016/j.mrfmmm.2021.111754","DOIUrl":"10.1016/j.mrfmmm.2021.111754","url":null,"abstract":"<div><p>We have extensively characterized base substitution mutations in the 795 base pair (bp) long <em>E. coli thyA</em> gene to define as many of the base substitution mutational sites that inactivate the gene as possible. The resulting catalog of mutational sites constitutes a system with up to 5 times as many sites for monitoring each of the six base substitution mutations as the widely used <em>rpoB</em>/Rif^r system. We have defined 75 sites for the G:C -&gt; A:T transition, 68 sites for the G:C -&gt; T:A transversion, 53 sites for the G:C -&gt; C:G transversion, 49 sites for the A:T -&gt; G:C transition, 39 sites for the A:T -&gt; T:A transversion, and 59 sites for the A:T -&gt; C:G transversion. The system is thus comprised of 343 base substitution mutations at 232 different base pairs, all of which can be sequenced with a single primer pair. This allows for the examination of mutational spectra using a more detailed probe of known mutations, while still allowing one to compare the number of repeated occurrences at specific sites. We have examined several mutagens and mutators with this system, and show its utility by looking at the spectrum of cisplatin, that has a single hotspot, underscoring the value of having as large an array of sites as possible at which one can monitor repeat occurrences. To test for regions of the gene that might be hotspots for a number of mutagens, or <strong>“</strong>hot” (mutaphilic) regions, we have looked at the ratio of mutations per set of an equal number of mutational sites throughout the gene. The resulting graphs suggest that there are “hot” regions at intervals, and this may reflect aspects of secondary structures, of the higher order structure of the chromosome, or perhaps the nucleoid structure of the chromosome plus histone-like protein complexes.</p></div>","PeriodicalId":49790,"journal":{"name":"Mutation Research-Fundamental and Molecular Mechanisms of Mutagenesis","volume":"823 ","pages":"Article 111754"},"PeriodicalIF":2.3,"publicationDate":"2021-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.mrfmmm.2021.111754","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39081212","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":"Origins of nonsense mutations in human tumor suppressor genes","authors":"Min Zhang,&nbsp;Da Yang,&nbsp;Barry Gold","doi":"10.1016/j.mrfmmm.2021.111761","DOIUrl":"10.1016/j.mrfmmm.2021.111761","url":null,"abstract":"<div><p>Understanding the origins of mutations in tumor suppressor genes and oncogenes associated with cancers in different tissues is critical to the development of potential prevention strategies. Analysis of &gt;10,000 nonsense mutations in 63 tumor suppressor genes based on the ratio of the number of nonsense mutations per codon type is reported for each gene. The ratio for C•G→T•A nonsense mutations at Arg CGA codons to the number of CGA codons in all cancers is 23 (3088 total nonsense mutations for 134 CGA codons in the 63 suppressor genes). The ratio for this codon, which is attributed to hydrolytic deamination of 5-methylcytosine at CpG sites based on the sequence context, is 6-fold higher than the next highest ratio that involves a C•G→T•A transition at Trp TGG codons. C•G→A•T transversions at Glu, Ser, Tyr, Gly and Cys codons account for 25 % of the total nonsense mutations but the mutation per codon ratio for these codons is 1.0. Analysis of the bases 5′ of the mutated CGA codons in the 63 tumor suppressor genes in all cancers shows a preference of 5′-G &gt; C ∼ T ∼ A, which is not indicative of a role for enzymatic deamination by deaminases. Overall C•G→T•A mutations account for 61 % of all of the nonsense mutations in the collection of tumor suppressor genes. It is demonstrated that the ratio of C•G→T•A deamination-associated nonsense mutations at CGA codons (hydrolytic deamination) to the number of frame shift insertion/deletion mutations (i.e., replication based) for 5 major tumor suppressors genes are very similar in 3 different tissues that undergo a wide range of stem cell divisions. Therefore, the frequency of deamination mutations parallels the number of stem cell replications. This may reflect the generation of more solvent accessible single-stranded DNA regions during polymerization that are kinetically more prone to deamination.</p></div>","PeriodicalId":49790,"journal":{"name":"Mutation Research-Fundamental and Molecular Mechanisms of Mutagenesis","volume":"823 ","pages":"Article 111761"},"PeriodicalIF":2.3,"publicationDate":"2021-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.mrfmmm.2021.111761","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39384299","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Biochemical and photochemical mechanisms that produce different UV-induced mutation spectra","authors":"Tomohiko Sugiyama ,&nbsp;Brianna Keinard ,&nbsp;Griffin Best ,&nbsp;Mahima R. Sanyal","doi":"10.1016/j.mrfmmm.2021.111762","DOIUrl":"10.1016/j.mrfmmm.2021.111762","url":null,"abstract":"<div><p>Although UV-induced mutagenesis has been studied extensively, the precise mechanisms that convert UV-induced DNA damage into mutations remain elusive. One well-studied mechanism involves DNA polymerase (Pol) η and ζ, which produces C &gt; T transitions during translesion synthesis (TLS) across pyrimidine dimers. We previously proposed another biochemical mechanism that involves multiple UV-irradiations with incubation in the dark in between. The incubation facilitates spontaneous deamination of cytosine in a pyrimidine dimer, and the subsequent UV irradiation induces photolyase-independent (direct) photoreversal that converts cytosine into monomeric uracil residue. In this paper, we first demonstrate that natural sunlight can induce both mutational processes <em>in vitro</em>. The direct photoreversal was also reproduced by monochromatic UVB at 300 nm. We also demonstrate that post-irradiation incubation in the dark is required for both mutational processes, suggesting that cytosine deamination is required for both the Pol η/ζ-dependent and the photoreversal-dependent mechanisms. Another Y-family polymerase Pol ι also mediated a mutagenic TLS on UV-damaged templates when combined with Pol ζ. The Pol ι-dependent mutations were largely independent of post-irradiation incubation, indicating that cytosine deamination was not essential for this mutational process. Sunlight-exposure also induced C &gt; A transversions which were likely caused by oxidation of guanine residues. Finally, we constructed <em>in vitro</em> mutation spectra in a comparable format to cancer mutation signatures. While both Pol η-dependent and photoreversal-dependent spectra showed high similarities to a cancer signature (SBS7a), Pol ι-dependent mutation spectrum has distinct T &gt; A/C substitutions, which are found in another cancer signature (SBS7d). The Pol ι-dependent T &gt; A/C substitutions were resistant to T4 pyrimidine dimer glycosylase-treatment, suggesting that this mutational process is independent of cis-syn pyrimidine dimers. An updated model about multiple mechanisms of UV-induced mutagenesis is discussed.</p></div>","PeriodicalId":49790,"journal":{"name":"Mutation Research-Fundamental and Molecular Mechanisms of Mutagenesis","volume":"823 ","pages":"Article 111762"},"PeriodicalIF":2.3,"publicationDate":"2021-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8671204/pdf/nihms-1741205.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39448169","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":"Radiation-induced DNA damage and altered expression of p21, cyclin D1 and Mre11 genes in human fibroblast cell lines with different radiosensitivity","authors":"Mohammad-Taghi Bahreyni-Toossi ,&nbsp;Hosein Azimian ,&nbsp;Seyed Hamid Aghaee-Bakhtiari ,&nbsp;Mahmoud Mahmoudi ,&nbsp;Mahdi Sadat- Darbandi ,&nbsp;Navid Zafari","doi":"10.1016/j.mrfmmm.2021.111760","DOIUrl":"10.1016/j.mrfmmm.2021.111760","url":null,"abstract":"<div><h3>Purpose</h3><p>Radiotherapy plays a pivotal role in the treatment of cancer. One of the main challenges in this treatment modality is radiation-induced complications in some patients affected by high radiosensitivity (RS). The differences in RS are determined mainly by genetic factors. Therefore, identifying the genes and mechanisms that affect RS in different cells is essential for evaluating radiotherapy outcomes. In the present study, the ability to repair DNA double-stranded breaks (DSB) is evaluated, followed by examining the expression levels of CDKN1A (p21), cyclinD1, and Mre11 genes in human fibroblasts with different RSs.</p></div><div><h3>Materials &amp; methods</h3><p>Cellular RS was measured by survival fraction at 2 Gy (SF2). The γ-H2AX assay was used for assessing DNA repair capacity. Eventually, gene expression levels from each cell line 4 and 24 h after irradiation (at 2, 4, and 8 Gy) were measured by real-time PCR.</p></div><div><h3>Results</h3><p>The SF2 values for the cell lines ranged from 0.286 to 0.641, and RS differences of fibroblast cells were identified. Among the studied genes, the expression of Mre11 was the most important. Analysis of the real-time PCR data showed that changes in Mre11 gene expression (4 h after 8 Gy irradiation) were directly correlated with the RS (R² = 0.905). The difference in the expression of the p21 gene (4 h after 4 Gy irradiation) was also promising. Finally, the flow cytometry analysis showed that the radioresistant cell lines quickly repaired DBS damages. However, the repair process was slow in the radiosensitive cell line, and the residual damage is significantly higher than other cell lines (P &lt; 0.01).</p></div><div><h3>Conclusions</h3><p>This study indicates that changes in the expression of p21 and Mre11 genes play an important role in cell response to radiation and thus these genes can be introduced as biomarkers to predict RS in normal cell lines.</p></div>","PeriodicalId":49790,"journal":{"name":"Mutation Research-Fundamental and Molecular Mechanisms of Mutagenesis","volume":"823 ","pages":"Article 111760"},"PeriodicalIF":2.3,"publicationDate":"2021-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.mrfmmm.2021.111760","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39309977","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"DNA damage-signaling, homologous recombination and genetic mutation induced by 5-azacytidine and DNA-protein crosslinks in Escherichia coli","authors":"Julie A. Klaric ,&nbsp;David J. Glass,&nbsp;Eli L. Perr ,&nbsp;Arianna D. Reuven ,&nbsp;Mason J. Towne,&nbsp;Susan T. Lovett","doi":"10.1016/j.mrfmmm.2021.111742","DOIUrl":"10.1016/j.mrfmmm.2021.111742","url":null,"abstract":"<div><p>Covalent linkage between DNA and proteins produces highly toxic lesions and can be caused by commonly used chemotherapeutic agents, by internal and external chemicals and by radiation. In this study, using <em>Escherichia coli</em>, we investigate the consequences of 5-azacytidine (5-azaC), which traps covalent complexes between itself and the Dcm cytosine methyltransferase protein. DNA protein crosslink-dependent effects can be ascertained by effects that arise in wild-type but not in <em>dcm</em>Δ strains. We find that 5-azaC induces the bacterial DNA damage response and stimulates homologous recombination, a component of which is Dcm-dependent. Template-switching at an imperfect inverted repeat (“quasipalindrome”, QP) is strongly enhanced by 5-azaC and this enhancement was entirely Dcm-dependent and independent of double-strand break repair. The SOS response helps ameliorate the mutagenic effect of 5-azaC but this is not a result of SOS-induced DNA polymerases since their induction, especially PolIV, seems to stimulate QP-associated mutagenesis. Cell division regulator SulA was also required for recovery of QP mutants induced by 5-azaC. In the absence of Lon protease, Dcm-dependent QP-mutagenesis is strongly elevated, suggesting it may play a role in DPC tolerance. Deletions at short tandem repeats, which occur likewise by a replication template-switch, are elevated, but only modestly, by 5-azaC. We see evidence for Dcm-dependent and-independent killing by 5-azaC in sensitive mutants, such as <em>recA</em>, <em>recB</em>, and <em>lon</em>; homologous recombination and deletion mutations are also stimulated in part by a Dcm-independent effect of 5-azaC. Whether this occurs by a different protein/DNA crosslink or by an alternative form of DNA damage is unknown</p></div>","PeriodicalId":49790,"journal":{"name":"Mutation Research-Fundamental and Molecular Mechanisms of Mutagenesis","volume":"822 ","pages":"Article 111742"},"PeriodicalIF":2.3,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.mrfmmm.2021.111742","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"25497617","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Note from the Publisher","authors":"","doi":"10.1016/j.mrfmmm.2021.111739","DOIUrl":"10.1016/j.mrfmmm.2021.111739","url":null,"abstract":"","PeriodicalId":49790,"journal":{"name":"Mutation Research-Fundamental and Molecular Mechanisms of Mutagenesis","volume":"822 ","pages":"Article 111739"},"PeriodicalIF":2.3,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.mrfmmm.2021.111739","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"25358523","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A gain-of-function mutation in CITED2 is associated with congenital heart disease","authors":"Manohar Lal Yadav ,&nbsp;Dharmendra Jain ,&nbsp;Neelabh ,&nbsp;Damyanti Agrawal ,&nbsp;Ashok Kumar ,&nbsp;Bhagyalaxmi Mohapatra","doi":"10.1016/j.mrfmmm.2021.111741","DOIUrl":"10.1016/j.mrfmmm.2021.111741","url":null,"abstract":"<div><p><span>CITED2 is a transcription co-activator that interacts with TFAP2 and CBP/ P300 transcription factors to regulate the proliferation and differentiation of the cardiac progenitor cells. It acts upstream to NODAL-PITX2 pathways and regulates the left-right asymmetry. Both human genetic and model organism studies have shown that altered expression of </span><em>CITED2</em><span> causes various forms of congenital heart disease. Therefore, we sought to screen the coding region of </span><em>CITED2</em><span><span> to identify rare genetic variants and assess their impact on the structure and function of the protein. Here, we have screened 271 non-syndromic, sporadic CHD cases by Sanger’s sequencing method and detected a non-synonymous variant (c.301C&gt;T, p.P101S) and two synonymous variants (c.21C&gt;A, p.A7A; c.627C&gt;G, p.P209P). The non-synonymous variant c.301C&gt;T (rs201639244) is a rare variant with a </span>minor allele frequency of 0.00011 in the gnomAD browser and 0.0018 in the present study. </span><em>in vitro</em> analysis has demonstrated that p.P101S mutation upregulates the expression of downstream target genes <em>Gata4, Mef2c, Nfatc1</em>&amp;<em>2</em>, <em>Nodal, Pitx2</em>, and <em>Tbx5</em><span> in P19 cells. Luciferase reporter assay also demonstrates enhanced activation of downstream target promoters. Further, </span><em>in silico</em><span> analyses implicate that increased activity of mutant CITED2 is possibly due to phosphorylation of Serine<span> residue by proline-directed kinases. Homology modeling<span><span> and alignment analysis have also depicted differences in hydrogen bonding and tertiary structures of wild-type versus </span>mutant protein. The impact of synonymous variations on the mRNA structure of </span></span></span><em>CITED2</em><span>has been analyzed by Mfold and relative codon bias calculations. Mfold results have revealed that both the synonymous variants can alter the mRNA structure and stability. Relative codon usage analysis has suggested that the rate of translation is attenuated due to these variations. Altogether, our results from genetic screening as well as in </span><em>vitro</em> and <em>in silico</em> studies support a possible role of nonsynonymous and synonymous mutations in <em>CITED2</em>contributing to pathogenesis of CHD.</p></div>","PeriodicalId":49790,"journal":{"name":"Mutation Research-Fundamental and Molecular Mechanisms of Mutagenesis","volume":"822 ","pages":"Article 111741"},"PeriodicalIF":2.3,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.mrfmmm.2021.111741","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"25477787","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}