Smc5/6-mediated regulation of replication progression contributes to chromosome assembly during mitosis in human cells.
Smc5/6-mediated regulation of replication progression contributes to chromosome assembly during mitosis in human cells.
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DOI：
10.1091/mbc.e13-01-0020
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发表时间：
2014-01
影响因子：
3.3
通讯作者：
Hirota T
中科院分区：
文献类型：
--
作者：
Gallego-Paez LM;Tanaka H;Bando M;Takahashi M;Nozaki N;Nakato R;Shirahige K;Hirota T
Smc 5/6复合体在DNA复制过程中起着关键作用，是有丝分裂中姐妹染色单体组装和忠实分离所不可或缺的。染色体结构维持蛋白（SMC）是参与染色体结构组织的关键复合物的核心。在酵母中，已知Smc 5/6复合物介导DNA断裂的修复和重复基因组区域的复制，包括核糖体DNA基因座和端粒。在具有与酵母不同的基因组结构和规模的哺乳动物细胞中，Smc 5/6复合物也与DNA损伤反应有关，但其在未受挑战的条件下的进一步功能仍然难以捉摸。在这项研究中，我们解决了Smc 5/6在细胞周期中的行为和功能。染色质分离，免疫荧光，和活细胞成像分析表明，Smc 5/6协会与染色质在间期，但很大程度上从染色体上解离时，他们在有丝分裂凝聚。Smc 5和Smc 6缺失导致异常的有丝分裂染色体表型，伴随着拓扑异构酶IIα（topo IIα）和凝聚素的异常分布以及染色体分离错误。重要的是，通过过早染色体凝聚试验表明的间期染色质结构表明，Smc 5/6是DNA复制和随后复制染色单体上topo IIα结合的按时进展所必需的。这些结果表明Smc 5/6复合物在处理DNA复制中的重要作用，这对于有丝分裂中正确的姐妹染色单体组装是必不可少的。
The Smc5/6 complex plays a critical role in processing DNA replication and is indispensable for sister chromatid assembly and faithful segregation in mitosis. The structural maintenance of chromosomes (SMC) proteins constitute the core of critical complexes involved in structural organization of chromosomes. In yeast, the Smc5/6 complex is known to mediate repair of DNA breaks and replication of repetitive genomic regions, including ribosomal DNA loci and telomeres. In mammalian cells, which have diverse genome structure and scale from yeast, the Smc5/6 complex has also been implicated in DNA damage response, but its further function in unchallenged conditions remains elusive. In this study, we addressed the behavior and function of Smc5/6 during the cell cycle. Chromatin fractionation, immunofluorescence, and live-cell imaging analyses indicated that Smc5/6 associates with chromatin during interphase but largely dissociates from chromosomes when they condense in mitosis. Depletion of Smc5 and Smc6 resulted in aberrant mitotic chromosome phenotypes that were accompanied by the abnormal distribution of topoisomerase IIα (topo IIα) and condensins and by chromosome segregation errors. Importantly, interphase chromatin structure indicated by the premature chromosome condensation assay suggested that Smc5/6 is required for the on-time progression of DNA replication and subsequent binding of topo IIα on replicated chromatids. These results indicate an essential role of the Smc5/6 complex in processing DNA replication, which becomes indispensable for proper sister chromatid assembly in mitosis.