Cdc7 kinase mediates Claspin phosphorylation in DNA replication checkpoint
Cdc7 kinase mediates Claspin phosphorylation in DNA replication checkpoint
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DOI：
10.1038/sj.onc.1210994
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发表时间：
2008-05-01
期刊：
影响因子：
8
通讯作者：
Masai, H.
中科院分区：
文献类型：
--
作者：
Kim, J. M.;Kakusho, N.;Masai, H.
Cdc 7激酶在进化上是保守的，并且参与DNA复制的起始和进展。然而，Cdc 7在检查点反应中的作用在很大程度上仍然未知。在这项研究中，我们发现，小鼠胚胎干细胞（ES）中的Cdc 7基因的缺失废除了羟基脲（HU）或紫外线诱导的Chk 1激活。HU诱导的Chk 1活化在Cdc 7被siRNA耗尽的人癌细胞系中也受损，并且Cdc 7耗尽的细胞对HU治疗更敏感。相比之下，ATR和Rad 17在HU处理后重新定位到这些细胞中的染色质，表明正常检测到停滞的DNA复制叉。Cdc 7缺失的细胞表现出染色质缔合和Claspin磷酸化的缺陷，表明Cdc 7至少部分地通过Claspin发挥其作用。与此预测一致，Cdc 7与Claspin相互作用并磷酸化Claspin。我们提出Cdc 7是通过调节Cl Aspin激活ATR-Chk 1检查点通路所必需的。
Cdc7 kinase is evolutionarily conserved and is involved in initiation and progression of DNA replication. However, roles of Cdc7 in checkpoint responses remain largely unknown. In this study, we show that deletion of the Cdc7 genes in mouse embryonic stem (ES) cells abrogates hydroxyurea (HU)- or UV-induced activation of Chk1. HU-induced Chk1 activation is also impaired in human cancer cell lines in which Cdc7 is depleted by siRNA, and Cdc7-depleted cells are more sensitive to HU treatment. In contrast, ATR and Rad17 are relocated to chromatin in these cells following HU treatment, indicating that stalled DNA replication forks are detected normally. Cdc7-depleted cells exhibit defects in chromatin association and phosphorylation of Claspin, suggesting that Cdc7 exerts its effect at least partially through Claspin. Consistent with this prediction, Cdc7 interacts with and phosphorylates Claspin. We propose that Cdc7 is required for activation of the ATR-Chk1 checkpoint pathway through regulation of Cl aspin.