Parp-1 protects homologous recombination from interference by Ku and ligase IV in vertebrate cells
Parp-1 protects homologous recombination from interference by Ku and ligase IV in vertebrate cells
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DOI：
10.1038/sj.emboj.7601015
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发表时间：
2006-03-22
期刊：
影响因子：
11.4
通讯作者：
Takeda, S
中科院分区：
文献类型：
--
作者：
Hochegger, H;Dejsuphong, D;Takeda, S
Parp-1和Parp-2被DNA断裂激活，并参与DNA单链断裂（SSB）的修复。它们参与同源重组（HR）或非同源末端连接（NHEJ）介导的双链断裂（DSB）修复仍不清楚。我们使用鸡DT40细胞解决了这个问题，该细胞具有仅携带PARP-1基因而不携带PARP-2基因的优势。我们发现PARP-1（-/-）DT 40突变体显示HR水平降低，对各种DSB诱导的遗传毒性药物敏感。令人惊讶的是，这种表型严格依赖于Ku的存在，Ku是一种介导NHEJ的DSB结合因子。PARP-1/KU70双突变体擅长HR的执行，并显示出对DSB诱导药物的耐药性升高。此外，我们发现另一个NHEJ基因Ligase IV的缺失抑制了PARP-1（-/-）细胞的喜树碱。我们的研究结果表明，在最大限度地减少Ku和NHEJ途径对HR的抑制作用，PARP的一个新的关键功能。
Parp-1 and Parp-2 are activated by DNA breaks and have been implicated in the repair of DNA single-strand breaks (SSB). Their involvement in double-strand break (DSB) repair mediated by homologous recombination (HR) or nonhomologous end joining (NHEJ) remains unclear. We addressed this question using chicken DT40 cells, which have the advantage of carrying only a PARP-1 gene but not a PARP-2 gene. We found that PARP-1(-/-) DT40 mutants show reduced levels of HR and are sensitive to various DSB-inducing genotoxic agents. Surprisingly, this phenotype was strictly dependent on the presence of Ku, a DSB-binding factor that mediates NHEJ. PARP-1/KU70 double mutants were proficient in the execution of HR and displayed elevated resistance to DSB-inducing drugs. Moreover, we found deletion of Ligase IV, another NHEJ gene, suppressed the camptothecin of PARP-1(-/-) cells. Our results suggest a new critical function for Parp in minimizing the suppressive effects of Ku and the NHEJ pathway on HR.