Artemis links ATM to G2/M checkpoint recovery via regulation of Cdk1-cyclin B
Artemis links ATM to G2/M checkpoint recovery via regulation of Cdk1-cyclin B
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DOI：
10.1128/mcb.02072-06
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发表时间：
2007-04-01
影响因子：
5.3
通讯作者：
Legerski, Randy J.
中科院分区：
文献类型：
--
作者：
Geng, Liyi;Zhang, Xiaoshan;Legerski, Randy J.
Artemis是一种磷酸化蛋白，已被证明在V（D）J重组、双链断裂的非同源末端连接和DNA损伤诱导的G（2）/M细胞周期检查点的调节中发挥作用。在这里，我们已经确定了四个网站在Artemis的磷酸化响应电离辐射（IR），并表明ATM是主要的激酶负责这些修改。其中两个位点S534和S538显示快速磷酸化和去磷酸化，另外两个位点S516和S645显示快速和延长的磷酸化。后两个残基的突变导致从G2/M细胞周期检查点的恢复缺陷。这种有缺陷的恢复是由于突变Artemis促进了未磷酸化的细胞周期蛋白B和CdkI之间增强的相互作用，这反过来又促进了Wee 1激酶对CdkI的抑制性磷酸化。此外，我们发现，突变体Artemis防止Cdk1-细胞周期蛋白B激活，导致其保留在中心体和抑制其核进口前期。这些发现表明，ATM通过抑制DNA损伤后不久发生的Artemis磷酸化来调节G（2）/M检查点恢复，从而设置一个分子开关，在DNA修复完成几小时后，允许激活Cdk 1-细胞周期蛋白B复合物。因此，这些发现确立了Artemis作为细胞周期调节剂对DNA损伤的反应的新功能。
Artemis is a phospho-protein that has been shown to have roles in V(D)J recombination, nonhomologous end-joining of double-strand breaks, and regulation of the DNA damage-induced G(2)/M cell cycle checkpoint. Here, we have identified four sites in Artemis that are phosphorylated in response to ionizing radiation (IR) and show that ATM is the major kinase responsible for these modifications. Two of the sites, S534 and S538, show rapid phosphorylation and dephosphorylation, and the other two sites, S516 and S645, exhibit rapid and prolonged phosphorylation. Mutation of both of these latter two residues results in defective recovery from the G2/M cell cycle checkpoint. This defective recovery is due to promotion by mutant Artemis of an enhanced interaction between unphosphorylated cyclin B and CdkI, which in turn promotes inhibitory phosphorylation of CdkI by the Wee1 kinase. In addition, we show that mutant Artemis prevents Cdk1-cyclin B activation by causing its retention in the centrosome and inhibition of its nuclear import during prophase. These findings show that ATM regulates G(2)/M checkpoint recovery through inhibitory phosphorylations of Artemis that occur soon after DNA damage, thus setting a molecular switch that, hours later upon completion of DNA repair, allows activation of the Cdk1-cyclin B complex. These findings thus establish a novel function of Artemis as a regulator of the cell cycle in response to DNA damage.