Disruption of the Rad9/Rad1/Hus1 (9-1-1) complex leads to checkpoint signaling and replication defects
Disruption of the Rad9/Rad1/Hus1 (9-1-1) complex leads to checkpoint signaling and replication defects
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DOI：
10.1038/sj.onc.1207753
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发表时间：
2004-07-22
期刊：
影响因子：
8
通讯作者：
Li, L
中科院分区：
文献类型：
--
作者：
Bao, SL;Lu, T;Li, L
检查点滑动钳复合物Rad 9/Rad 1/Hus 1在响应DNA损伤和复制中断的检查点信号启动过程中起着关键作用。我们研究了Rad 1缺失对哺乳动物细胞中检查点功能和DNA复制的影响。我们表明，RAD 1是一个持续的细胞增殖的必要基因，并认为Rad 1的损失导致Rad 9和Hus 1的不稳定，从而解体的滑动钳复合物。在Rad 1耗竭细胞中，Atr依赖的Chk 1激活受损，而Atm介导的Chk 2激活不受影响，这表明滑动钳主要是Atr依赖的信号激活所需的。滑动箝位功能的中断也造成了S相控制的重大缺陷。Rad 1耗尽细胞表现出RDS表型，表明损伤诱导的S期阻滞受到Rad 1损失的影响。此外，缺乏Rad 1也影响了DNA合成阻断后复制恢复的效率，导致S期延长。这些缺陷可能会永久地产生DNA链断裂，因为我们已经发现在Rad 1缺失的细胞中染色体异常。我们的结论是，Rad 9/Rad 1/Hus 1复合物是必不可少的ATR依赖的检查点信号，这可能在促进DNA复制和维持基因组的完整性发挥关键作用。
The checkpoint sliding-clamp complex, Rad9/Rad1/Hus1, plays a critical role during initiation of checkpoint signals in response to DNA damage and replication disruption. We investigated the impact of loss of Rad1 on checkpoint function and on DNA replication in mammalian cells. We show that RAD1 is an essential gene for sustained cell proliferation and that loss of Rad1 causes destabilization of Rad9 and Hus1 and consequently disintegration of the sliding-clamp - complex. In Rad1-depleted cells, Atr-dependent Chk1 activation was impaired whereas Atm-mediated Chk2 activation was unaffected, suggesting that the sliding clamp is required primarily in Atr-dependent signal activation. Disruption of sliding-clamp function also caused a major defect in S-phase control. Rad1-depleted cells exhibited an RDS phenotype, indicating that damage-induced S-phase arrest was compromised by Rad1 loss. Furthermore, lack of Rad1 also affected the efficiency of replication recovery from DNA synthesis blockage, resulting in a prolonged S phase. These deficiencies may perpetually generate DNA strand breakage as we have found chromosomal abnormalities in Rad1-depleted cells. We conclude that the Rad9/Rad1/Hus1 complex is essential for Atr-dependent checkpoint signaling, which may play critical roles in the facilitation of DNA replication and in the maintenance of genomic integrity.