Porcher Latarsha, Vijayraghavan Sriram, McCollum James, Mieczkowski Piotr A, Saini Natalie
Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, South Carolina, 29425, United States of America.
Department of Genetics, Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina, 27599, United States of America.
bioRxiv. 2024 Jan 8:2024.01.07.574575. doi: 10.1101/2024.01.07.574575.
Acetaldehyde is the primary metabolite of alcohol and is present in many environmental sources including tobacco smoke. Acetaldehyde is genotoxic, whereby it can form DNA adducts and lead to mutagenesis. Individuals with defects in acetaldehyde clearance pathways have increased susceptibility to alcohol-associated cancers. Moreover, a mutation signature specific to acetaldehyde exposure is widespread in alcohol and smoking-associated cancers. However, the pathways that repair acetaldehyde-induced DNA damage and thus prevent mutagenesis are vaguely understood. Here, we used to systematically delete genes in each of the major DNA repair pathways to identify those that alter acetaldehyde-induced mutagenesis. We found that deletion of the nucleotide excision repair (NER) genes, or , led to an increase in mutagenesis upon acetaldehyde exposure. Acetaldehyde-induced mutations were dependent on translesion synthesis as well as DNA inter-strand crosslink (ICL) repair in strains. Moreover, whole genome sequencing of the mutated isolates demonstrated an increase in C→A changes coupled with an enrichment of gCn→A changes in the acetaldehyde-treated isolates. The gCn→A mutation signature has been shown to be diagnostic of acetaldehyde exposure in yeast and in human cancers. We also demonstrated that the deletion of the two DNA-protein crosslink (DPC) repair proteases, and , also led to increased acetaldehyde-induced mutagenesis. Defects in base excision repair (BER) led to a mild increase in mutagenesis, while defects in mismatch repair (MMR), homologous recombination repair (HR) and post replicative repair pathways did not impact mutagenesis upon acetaldehyde exposure. Our results in yeast were further corroborated upon analysis of whole exome sequenced liver cancers, wherein, tumors with defects in ERCC1 and ERCC4 (NER), FANCD2 (ICL repair) or SPRTN (DPC repair) carried a higher gCn→A mutation load than tumors with no deleterious mutations in these genes. Our findings demonstrate that multiple DNA repair pathways protect against acetaldehyde-induced mutagenesis.
乙醛是酒精的主要代谢产物，存在于包括烟草烟雾在内的许多环境来源中。乙醛具有基因毒性，可形成DNA加合物并导致诱变。乙醛清除途径存在缺陷的个体对酒精相关癌症的易感性增加。此外，乙醛暴露特有的突变特征在酒精和吸烟相关癌症中广泛存在。然而，修复乙醛诱导的DNA损伤从而预防诱变的途径仍不甚明了。在此，我们利用[具体方法]系统地删除了每个主要DNA修复途径中的基因，以确定那些改变乙醛诱导诱变的基因。我们发现，核苷酸切除修复（NER）基因[具体基因名称1]或[具体基因名称2]的缺失导致乙醛暴露后诱变增加。在[具体菌株名称]菌株中，乙醛诱导的突变依赖于跨损伤合成以及DNA链间交联（ICL）修复。此外，对突变分离株的全基因组测序表明，乙醛处理的[具体菌株名称]分离株中C→A变化增加，同时gCn→A变化富集。gCn→A突变特征已被证明可诊断酵母和人类癌症中的乙醛暴露。我们还证明，两种DNA - 蛋白质交联（DPC）修复蛋白酶[具体蛋白酶名称1]和[具体蛋白酶名称2]的缺失也导致乙醛诱导的诱变增加。碱基切除修复（BER）缺陷导致诱变轻度增加，而错配修复（MMR）、同源重组修复（HR）和复制后修复途径的缺陷在乙醛暴露时不影响诱变。对全外显子测序的肝癌进行分析后，进一步证实了我们在酵母中的结果，其中，ERCC1和ERCC4（NER）、FANCD2（ICL修复）或SPRTN（DPC修复）存在缺陷的肿瘤比这些基因无有害突变的肿瘤携带更高的gCn→A突变负荷。我们的研究结果表明，多种DNA修复途径可防止乙醛诱导的诱变。
