Phosphorylation sites on Tyr28 and the C-terminus of Rad9 are required for inhibition of premature chromosomal condensation across the entire S phase
Phosphorylation sites on Tyr28 and the C-terminus of Rad9 are required for inhibition of premature chromosomal condensation across the entire S phase
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Tyr28 和 Rad9 C 末端的磷酸化位点是抑制整个 S 期染色体过早凝结所必需的
DOI：
10.1159/000149808
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发表时间：
2008-01-01
影响因子：
--
通讯作者：
Hang, Haiying
中科院分区：
文献类型：
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作者：
Zhang, Chunbo;Zhang, Charles Xia;Hang, Haiying
Rad 9是基因毒素诱导的检查点信号通路的活性所必需的，以控制细胞周期进程并维持基因组稳定性。在裂殖酵母S.在Pombe和鸡细胞中，Rad 9基因对于防止过早的染色体凝聚（PCC：S/M检查点控制）是必不可少的。然而，哺乳动物细胞中由Rad 9控制的S/M检查点的精确特征仍然不清楚。在这项研究中，小鼠胚胎干（ES）细胞与Mrad 9，S。pombe rad 9，用于评估Mrad 9在S/M检查点控制中的详细功能。我们发现，从ES细胞中删除Mrad 9会导致整个S期的S/M检查点控制失败，并通过将小鼠或人Rad 9引入Mrad 9删除的细胞中来缓解。我们还发现Tyr 28和Rad 9的C-末端上的磷酸化位点是该检查点控制所需的。此外，DNA复制抑制剂羟基脲（HU）诱导cdc 2 Tyr 15磷酸化和增加14-3-3 sigma蛋白水平在Mrad 9（+/+）ES细胞，但不能这样做在Mrad 9（-/-）ES细胞。总之，这些结果表明，Rad 9的磷酸化在S/M检查点的激活中起着关键作用，并且下游蛋白cdc 2和14-3-3 sigma介导了该功能。版权所有（C）2008 S. Karger AG，巴塞尔。
Rad9 is required for the activity of the genotoxininduced checkpoint signaling pathway to control cell cycle progress and maintain genomic stability. In the fission yeast S. Pombe and chicken cells, the Rad9 gene is essential for prevention of premature chromosomal condensation (PCC:S/M checkpoint control). However, precise features in the S/M checkpoint controlled by Rad9 in mammalian cells are still not clear. In this study, mouse embryonic stem (ES) cells with a targeted deletion of Mrad9, the counterpart of S. pombe rad9, were used to evaluate the detailed function of Mrad9 in S/M checkpoint control. We found that Mrad9 deletion from ES cells led to failure of S/M checkpoint control across the entire S phase, and was alleviated by introducing mouse or human Rad9 into the Mrad9-deleted cells. We also found that the phosphorylation sites on Tyr28 and the C-terminus of Rad9 are required for this checkpoint control. Moreover, the DNA replication inhibitor hydroxyurea (HU) induced cdc2 Tyr15 phosphorylation and increased 14-3-3 sigma protein levels in Mrad9(+/+) ES cells, but failed to do so in Mrad9(-/-) ES cells. Taken together, these results suggest that phosphorylation of Rad9 plays a critical role in the activation of the S/M checkpoint, and that downstream proteins cdc2 and 14-3-3 sigma mediate this function. Copyright (C) 2008 S. Karger AG, Basel.