DNA double-strand breaks with 5' adducts are efficiently channeled to the DNA2-mediated resection pathway.
DNA double-strand breaks with 5' adducts are efficiently channeled to the DNA2-mediated resection pathway.
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带有 5 加合物的 DNA 双链断裂被有效引导至 DNA2 介导的切除途径。
DOI：
10.1093/nar/gkv969
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发表时间：
2016
影响因子：
14.9
通讯作者：
Yan,Hong
中科院分区：
文献类型：
--
作者：
Tammaro,Margaret;Liao,Shuren;Beeharry,Neil;Yan,Hong
具有 5' 加合物的 DNA 双链断裂 (DSB) 经常由许多核酸加工酶形成，特别是 DNA 拓扑异构酶 2 (TOP2)。 TOP2 催化的关键中间体是共价复合物 (TOP2cc)，由两个共价连接到切口 DNA 5' 端的 TOP2 亚基组成。在细胞中，TOP2cc 可以被依托泊苷等癌症药物捕获，然后转化为 DNA 双链断裂 (DSB)，在 5' 端携带加合物。这种 DSB 的修复对于细胞的生存至关重要，但其潜在机制仍不清楚。我们发现依托泊苷诱导的 DSB 可以有效地切除细胞中的 3' 单链 DNA，并且切除的主要核酸酶是 DNA2 蛋白。携带模型 5' 加合物的 DNA 底物在非洲爪蟾提取物中被有效切除，并且非洲爪蟾 DNA2 的免疫耗竭也强烈抑制切除。这些结果表明DNA2介导的切除是修复具有5'加合物的DSB的主要机制。
DNA double-strand breaks (DSBs) with 5′ adducts are frequently formed from many nucleic acid processing enzymes, in particular DNA topoisomerase 2 (TOP2). The key intermediate of TOP2 catalysis is the covalent complex (TOP2cc), consisting of two TOP2 subunits covalently linked to the 5′ ends of the nicked DNA. In cells, TOP2ccs can be trapped by cancer drugs such as etoposide and then converted into DNA double-strand breaks (DSBs) that carry adducts at the 5′ end. The repair of such DSBs is critical to the survival of cells, but the underlying mechanism is still not well understood. We found that etoposide-induced DSBs are efficiently resected into 3′ single-stranded DNA in cells and the major nuclease for resection is the DNA2 protein. DNA substrates carrying model 5′ adducts were efficiently resected inXenopusegg extracts and immunodepletion ofXenopusDNA2 also strongly inhibited resection. These results suggest that DNA2-mediated resection is a major mechanism for the repair of DSBs with 5′ adducts.