Repair of double-strand breaks by nonhomologous end joining in the absence of Mre11.
Repair of double-strand breaks by nonhomologous end joining in the absence of Mre11.
复制标题
DOI：
10.1083/jcb.200506029
复制
发表时间：
2005-12-05
影响因子：
7.8
通讯作者：
Gautier, Jean
中科院分区：
文献类型：
--
作者：
Di Virgilio, Michela;Gautier, Jean
Mre 11-Rad 50-Nbs 1（MRN）复合物参与非同源末端连接（NHEJ）是有争议的。MRN复合物是酿酒酵母中NHEJ所需的，但在粟酒裂殖酵母中不需要。在脊椎动物中，Mre 11，Rad 50和Nbs 1是必需基因，研究仅限于携带Mre 11或Nbs 1亚型突变的细胞，这些细胞仍然执行几种MRN复合物相关活动。在这项研究中，我们分析了Mre 11损失的脊椎动物NHEJ的机制，通过使用染色质化质粒双链断裂（DSB）修复试验在非洲爪蟾的无细胞提取物的影响。Mre 11缺失的提取物能够支持DSB的有效NHEJ修复，而不管末端结构如何。Mre 11缺失不会改变末端连接的动力学或修复产物中发现的连接的类型和频率。最后，Ku 70独立的末端连接事件不受Mre 11损失的影响。我们的数据表明，在这种脊椎动物系统中，MRN复合物对于NHEJ介导的DSB的有效和准确的修复是不需要的。
Mre11–Rad50–Nbs1 (MRN) complex involvement in nonhomologous end joining (NHEJ) is controversial. The MRN complex is required for NHEJ in Saccharomyces cerevisiae but not in Schizosaccharomyces pombe. In vertebrates, Mre11, Rad50, and Nbs1 are essential genes, and studies have been limited to cells carrying hypomorphic mutations in Mre11 or Nbs1, which still perform several MRN complex–associated activities. In this study, we analyze the effects of Mre11 loss on the mechanism of vertebrate NHEJ by using a chromatinized plasmid double-strand break (DSB) repair assay in cell-free extracts from Xenopus laevis. Mre11-depleted extracts are able to support efficient NHEJ repair of DSBs regardless of the end structure. Mre11 depletion does not alter the kinetics of end joining or the type and frequency of junctions found in repaired products. Finally, Ku70-independent end-joining events are not affected by Mre11 loss. Our data demonstrate that the MRN complex is not required for efficient and accurate NHEJ-mediated repair of DSBs in this vertebrate system.