Recovery from DNA damage checkpoint arrest by PP1-mediated inhibition of Chk1
Recovery from DNA damage checkpoint arrest by PP1-mediated inhibition of Chk1
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DOI：
10.1038/sj.emboj.7600105
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发表时间：
2004-02-25
期刊：
影响因子：
11.4
通讯作者：
O'Connell, MJ
中科院分区：
文献类型：
--
作者：
den Elzen, NR;O'Connell, MJ
G2 DNA损伤检查点通过上调Wee 1激酶和下调Cdc 25磷酸酶来延迟有丝分裂进入，并由此抑制Cdc 2的磷酸化。虽然检查点激活是很好理解的，但很少有人知道检查点是如何关闭的，以允许细胞周期重新进入。为了鉴定检查点释放所需的蛋白质，我们筛选了粟酒裂殖酵母中的基因，当过表达时，在DNA损伤的存在下导致早熟有丝分裂进入。我们发现，过表达的I型蛋白磷酸酶Dis 2敏感S。粟酒裂殖酵母细胞的DNA损伤，导致异常的有丝分裂。Dis 2在体内消除Chk 1磷酸化和激活，并在体外使Chk 1和磷酸化-S345 Chk 1肽去磷酸化。dis 2Delta细胞具有延长的chk 1依赖性停滞和降低Chk 1活性以释放检查点的能力。这些效应是DNA损伤检查点特有的，因为Dis 2对chk 1独立的对停滞复制叉的反应没有影响。我们建议，失活的Chk 1的Dis 2允许有丝分裂进入后修复的DNA损伤在G2期。
The G2 DNA damage checkpoint delays mitotic entry via the upregulation of Wee1 kinase and the downregulation of Cdc25 phosphatase by Chk1 kinase, and resultant inhibitory phosphorylation of Cdc2. While checkpoint activation is well understood, little is known about how the checkpoint is switched off to allow cell cycle re-entry. To identify proteins required for checkpoint release, we screened for genes in Schizosaccharomyces pombe that, when overexpressed, result in precocious mitotic entry in the presence of DNA damage. We show that overexpression of the type I protein phosphatase Dis2 sensitises S. pombe cells to DNA damage, causing aberrant mitoses. Dis2 abrogates Chk1 phosphorylation and activation in vivo, and dephosphorylates Chk1 and a phospho-S345 Chk1 peptide in vitro. dis2Delta cells have a prolonged chk1-dependent arrest and a compromised ability to downregulate Chk1 activity for checkpoint release. These effects are specific for the DNA damage checkpoint, because Dis2 has no effect on the chk1-independent response to stalled replication forks. We propose that inactivation of Chk1 by Dis2 allows mitotic entry following repair of DNA damage in the G2-phase.