Homologous recombination-dependent repair of telomeric DSBs in proliferating human cells.
Homologous recombination-dependent repair of telomeric DSBs in proliferating human cells.
复制标题
增殖人类细胞中端粒 DSB 的同源重组依赖性修复
DOI：
10.1038/ncomms12154
复制
发表时间：
2016-07-11
影响因子：
16.6
通讯作者：
Zhao Y
中科院分区：
文献类型：
--
作者：
Mao P;Liu J;Zhang Z;Zhang H;Liu H;Gao S;Rong YS;Zhao Y
端粒防止染色体末端被识别为双链断裂（DSB）。同时，富含G/C的重复端粒DNA容易受到DNA损伤剂的攻击。细胞如何平衡保护DNA末端的需要和修复端粒中DNA损伤的需要尚不清楚。在这里，我们表明，端粒DSB在增殖细胞中被有效修复，但在应激诱导和复制衰老细胞中是不可修复的。使用CRISPR-Cas9技术，我们在端粒或亚端粒区域特异性诱导DSB。我们发现，DSB修复（DSBR）在亚端粒发生在一个错误倾向的方式导致小的缺失，提示NHEJ。然而，端粒中的DSBR涉及“端粒簇集”，3′-突出的富含C的端粒ssDNA，以及姐妹染色单体或染色体间端粒之间的HR。端粒中的DSBR通过Rad 51的缺失或抑制而被抑制。这些研究结果揭示了端粒中的增殖依赖性DSBR，并表明端粒HR，这是正常的组成性抑制，在DSBR的背景下被激活。
Telomeres prevent chromosome ends from being recognized as double-stranded breaks (DSBs). Meanwhile, G/C-rich repetitive telomeric DNA is susceptible to attack by DNA-damaging agents. How cells balance the need to protect DNA ends and the need to repair DNA lesions in telomeres is unknown. Here we show that telomeric DSBs are efficiently repaired in proliferating cells, but are irreparable in stress-induced and replicatively senescent cells. Using the CRISPR-Cas9 technique, we specifically induce DSBs at telomeric or subtelomeric regions. We find that DSB repair (DSBR) at subtelomeres occurs in an error-prone manner resulting in small deletions, suggestive of NHEJ. However, DSBR in telomeres involves ‘telomere-clustering’, 3′-protruding C-rich telomeric ssDNA, and HR between sister-chromatid or interchromosomal telomeres. DSBR in telomeres is suppressed by deletion or inhibition of Rad51. These findings reveal proliferation-dependent DSBR in telomeres and suggest that telomeric HR, which is normally constitutively suppressed, is activated in the context of DSBR.