作者:Michael R. Hodskinson、Alice Bolner、Koichi Sato、Ashley N. Kamimae-Lanning、Koos Rooijers、Merlijn Witte、Mohan Mahesh、Jan Silhan、Maya Petek、David M. Williams、Jop Kind、Jason W. Chin、Ketan J. Patel、Puck Knipscheer
DOI:10.1038/s41586-020-2059-5
日期:2020.3.26
Acetaldehyde is a highly reactive, DNA-damaging metabolite that is produced upon alcohol consumption1. Impaired detoxification of acetaldehyde is common in the Asian population, and is associated with alcohol-related cancers1,2. Cells are protected against acetaldehyde-induced damage by DNA crosslink repair, which when impaired causes Fanconi anaemia (FA), a disease resulting in failure to produce blood cells and a predisposition to cancer3,4. The combined inactivation of acetaldehyde detoxification and the FA pathway induces mutation, accelerates malignancies and causes the rapid attrition of blood stem cells5â7. However, the nature of the DNA damage induced by acetaldehyde and how this is repaired remains a key question. Here we generate acetaldehyde-induced DNA interstrand crosslinks and determine their repair mechanism in Xenopus egg extracts. We find that two replication-coupled pathways repair these lesions. The first is the FA pathway, which operates using excisionâanalogous to the mechanism used to repair the interstrand crosslinks caused by the chemotherapeutic agent cisplatin. However, the repair of acetaldehyde-induced crosslinks results in increased mutation frequency and an altered mutational spectrum compared with the repair of cisplatin-induced crosslinks. The second repair mechanism requires replication fork convergence, but does not involve DNA incisionsâinstead the acetaldehyde crosslink itself is broken. The Y-family DNA polymerase REV1 completes repair of the crosslink, culminating in a distinct mutational spectrum. These results define the repair pathways of DNA interstrand crosslinks caused by an endogenous and alcohol-derived metabolite, and identify an excision-independent mechanism. DNA interstrand crosslinks induced by acetaldehyde are repaired by both the Fanconi anaemia pathway and by a second, excision-independent repair mechanism.
乙醛是一种高反应性、损害 DNA 的代谢产物,在饮酒后产生。亚洲人群中乙醛解毒能力受损的情况很常见,并与酒精相关的癌症有关。细胞通过 DNA 交联修复来保护自己免受乙醛引起的损伤,当这种修复受损时,会导致范可尼贫血(FA),这是一种导致血细胞生成失败和癌症倾向的疾病。乙醛解毒和 FA 通路的联合失活会诱发突变,加速恶性肿瘤的发生,并导致血液干细胞的快速消耗。然而,乙醛诱导的 DNA 损伤的性质及其修复机制仍然是一个关键问题。在这里,我们生成了乙醛诱导的 DNA 跨链交联,并在非洲爪蛙卵提取物中确定其修复机制。我们发现有两个与复制相关的通路修复这些损伤。第一个是 FA 通路,其通过切除机制运作,类似于用于修复化疗药物顺铂引起的跨链交联的机制。然而,乙醛诱导的交联修复与顺铂诱导的交联修复相比,导致突变频率增加和突变谱的变化。第二种修复机制需要复制叉的汇聚,但不涉及 DNA 切口,而是直接打破乙醛交联本身。Y 家族 DNA 聚合酶 REV1 完成交联的修复,最终产生一种独特的突变谱。这些结果定义了内源性和酒精衍生代谢产物引起的 DNA 跨链交联的修复通路,并鉴定出了一种不依赖切除的修复机制。乙醛诱导的 DNA 跨链交联通过范可尼贫血通路和第二种独立于切除的修复机制修复。