Rapid Recruitment of BRCA1 to DNA Double-Strand Breaks Is Dependent on Its Association with Ku80
Rapid Recruitment of BRCA1 to DNA Double-Strand Breaks Is Dependent on Its Association with Ku80
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DOI：
10.1128/mcb.01075-08
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发表时间：
2008-10
影响因子：
5.3
通讯作者：
Leizhen Wei;Li Lan;Zehui Hong;A. Yasui;C. Ishioka;N. Chiba
中科院分区：
文献类型：
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作者：
Leizhen Wei;Li Lan;Zehui Hong;A. Yasui;C. Ishioka;N. Chiba
摘要BRCA 1是第一个与乳腺癌和卵巢癌相关的易感基因。尽管越来越多的证据表明BRCA 1参与DNA双链断裂（DSB）修复途径，但其确切机制仍不清楚。在这里，我们分析了BRCA 1在激光微照射产生的DSBs的原位响应。BRCA 1的氨基（N）-和羧基（C）-末端片段在DSB中以不同的动力学独立积累。N-末端BRCA 1片段在激光照射后立即聚集在DSB并迅速解离。相反，BRCA 1的C-末端片段在DSB中积累得更慢，但仍保留在位点上。有趣的是，BRCA 1 N端而不是C端在DSB的快速积累依赖于Ku 80，Ku 80在非同源末端连接（NHEJ）途径中发挥作用，独立于BARD 1，BARD 1与BRCA 1的N端结合。BRCA 1的N末端的两个小区域独立地积累在DSB处并与Ku 80相互作用。在癌症中BRCA 1的N末端发现的错义突变显著改变了其在DSB中积累的动力学。P142 H突变体未能与Ku 80结合并恢复BRCA 1缺陷细胞的辐射抗性。这可能为BRCA 1参与DSB修复过程中的NHEJ通路提供了分子基础。
ABSTRACT BRCA1 is the first susceptibility gene to be linked to breast and ovarian cancers. Although mounting evidence has indicated that BRCA1 participates in DNA double-strand break (DSB) repair pathways, its precise mechanism is still unclear. Here, we analyzed the in situ response of BRCA1 at DSBs produced by laser microirradiation. The amino (N)- and carboxyl (C)-terminal fragments of BRCA1 accumulated independently at DSBs with distinct kinetics. The N-terminal BRCA1 fragment accumulated immediately after laser irradiation at DSBs and dissociated rapidly. In contrast, the C-terminal fragment of BRCA1 accumulated more slowly at DSBs but remained at the sites. Interestingly, rapid accumulation of the BRCA1 N terminus, but not the C terminus, at DSBs depended on Ku80, which functions in the nonhomologous end-joining (NHEJ) pathway, independently of BARD1, which binds to the N terminus of BRCA1. Two small regions in the N terminus of BRCA1 independently accumulated at DSBs and interacted with Ku80. Missense mutations found within the N terminus of BRCA1 in cancers significantly changed the kinetics of its accumulation at DSBs. A P142H mutant failed to associate with Ku80 and restore resistance to irradiation in BRCA1-deficient cells. These might provide a molecular basis of the involvement of BRCA1 in the NHEJ pathway of the DSB repair process.