Human Timeless and Tipin stabilize replication forks and facilitate sister-chromatid cohesion
Human Timeless and Tipin stabilize replication forks and facilitate sister-chromatid cohesion
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DOI：
10.1242/jcs.057984
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发表时间：
2010-03-01
影响因子：
4
通讯作者：
Noguchi, Eishi
中科院分区：
文献类型：
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作者：
Leman, Adam R.;Noguchi, Chiaki;Noguchi, Eishi
据报道，Timless-tipin蛋白复合体对于复制检查点和正常的DNA复制过程是重要的。然而，Timless-TIPIN保持基因组完整性的确切机制在很大程度上还不清楚。在这里，我们描述了TIMENTER-TIPIN在复制分叉稳定和姐妹染色单体凝聚力中的作用。我们在人类细胞中显示，Timless被招募到复制起始区，并随着复制的进行而与它们分离。已知的复制分叉进程所需的CDC45显示出与Timless相似的起源关联模式。Timless-Tipin的耗尽会导致染色体断裂和损伤修复中的缺陷，以响应叉子的崩溃，这表明它是逆境下复制叉子维持所必需的。我们还证明，Timless-Tipin的缺失会损害姐妹染色单体的凝聚力，并导致有丝分裂进程中的缺陷。TIMENTESS-TIPIN始终与粘附素亚基协同纯化，在S期与染色质稳定结合是必需的。TIMENTER与促进凝聚力的DNA解旋酶ChlR1有关，当过度表达时，可以部分缓解TIMENTER-TIPIN缺失的细胞的凝聚力缺陷。这些结果表明，Timless-TIPIN作为复制叉稳定剂，将DNA复制与复制叉处建立的姐妹染色单体凝聚力结合在一起。
The Timeless-Tipin protein complex has been reported to be important for replication checkpoint and normal DNA replication processes. However, the precise mechanisms by which Timeless-Tipin preserves genomic integrity are largely unclear. Here, we describe the roles of Timeless-Tipin in replication fork stabilization and sister chromatid cohesion. We show in human cells that Timeless is recruited to replication origin regions and dissociate from them as replication proceeds. Cdc45, which is known to be required for replication fork progression, shows similar patterns of origin association to those of Timeless. Depletion of Timeless-Tipin causes chromosome fragmentation and defects in damage repair in response to fork collapse, suggesting that it is required for replication fork maintenance under stress. We also demonstrate that depletion of Timeless-Tipin impairs sister chromatid cohesion and causes a defect in mitotic progression. Consistently, Timeless-Tipin co-purifies with cohesin subunits and is required for their stable association with chromatin during S phase. Timeless associates with the cohesion-promoting DNA helicase ChlR1, which, when overexpressed, partially alleviates the cohesion defect of cells depleted of Timeless-Tipin. These results suggest that Timeless-Tipin functions as a replication fork stabilizer that couples DNA replication with sister chromatid cohesion established at replication forks.