DNA ligase IV and artemis act cooperatively to suppress homologous recombination in human cells: implications for DNA double-strand break repair.
DNA ligase IV and artemis act cooperatively to suppress homologous recombination in human cells: implications for DNA double-strand break repair.
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DOI：
10.1371/journal.pone.0072253
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发表时间：
2013
期刊：
影响因子：
3.7
通讯作者：
Adachi N
中科院分区：
文献类型：
--
作者：
Kurosawa A;Saito S;So S;Hashimoto M;Iwabuchi K;Watabe H;Adachi N
非同源末端连接（NHEJ）和同源重组（HR）是修复DNA双链断裂（DSB）的两条主要途径，但它们在人体细胞中的作用尚不清楚。在这里，我们使用一系列的人类基因敲除细胞系，NHEJ修复几乎所有的拓扑异构酶II和低剂量辐射诱导的DNA损伤，而它对携带复制相关DSB的细胞的存活产生负面影响。有趣的是，我们发现DNA连接酶IV（一种关键的NHEJ连接酶）和Artemis（一种具有核酸内切酶活性的NHEJ因子）的缺失独立地导致对复制相关DSB的抗性增加。我们还表明，Artemis的丧失使DNA连接酶IV无效的细胞对低剂量辐射和拓扑异构酶II诱导的DSB产生超敏反应。最后，我们证明了Artemis无效的人类细胞显示出增加的基因靶向效率，特别是在没有DNA连接酶IV的情况下。总的来说，这些数据表明，DNA连接酶IV和阿耳忒弥斯合作，以促进NHEJ，从而抑制HR.Our结果点的可能性，HR只能在偶然的DSB操作时，NHEJ是失踪或流产，和阿耳忒弥斯可能参与从不完整的NHEJ到HR的通路切换。
Nonhomologous end-joining (NHEJ) and homologous recombination (HR) are two major pathways for repairing DNA double-strand breaks (DSBs); however, their respective roles in human somatic cells remain to be elucidated. Here we show using a series of human gene-knockout cell lines that NHEJ repairs nearly all of the topoisomerase II- and low-dose radiation-induced DNA damage, while it negatively affects survival of cells harbouring replication-associated DSBs. Intriguingly, we find that loss of DNA ligase IV, a critical NHEJ ligase, and Artemis, an NHEJ factor with endonuclease activity, independently contribute to increased resistance to replication-associated DSBs. We also show that loss of Artemis alleviates hypersensitivity of DNA ligase IV-null cells to low-dose radiation- and topoisomerase II-induced DSBs. Finally, we demonstrate that Artemis-null human cells display increased gene-targeting efficiencies, particularly in the absence of DNA ligase IV. Collectively, these data suggest that DNA ligase IV and Artemis act cooperatively to promote NHEJ, thereby suppressing HR. Our results point to the possibility that HR can only operate on accidental DSBs when NHEJ is missing or abortive, and Artemis may be involved in pathway switching from incomplete NHEJ to HR.
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