Division of Life Science, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, PR China.
Biochem Biophys Res Commun. 2011 Sep 30;413(3):465-70. doi: 10.1016/j.bbrc.2011.08.119. Epub 2011 Sep 1.
It has been reported previously that both Cdk1 and Cdk2 phosphorylate Chk1 in a cell-cycle dependent manner. Cdk-mediated phosphorylation is required for efficient activation of Chk1 and checkpoint proficiency in response to DNA damage. Here, we demonstrate that Cdk-mediated phosphorylation is also required for replication stress induced Chk1 activation and S/M checkpoint proficiency. Re-introduction of Chk1 mutant (S286A/S301A) into Chk1 deficient cells is capable of restraining mitosis in cells with completely unreplicated DNA, but the mitotic delay at later stage of the cell cycle is largely impaired. The mutation strongly attenuates aphidicolin induced Chk1 activation without altering the S-phase dependent Chk1 activation. These data indicate that Cdk-mediated phosphorytion is required for efficient Chk1 activation and multiple checkpoint proficiency.
先前有报道称，Cdk1 和 Cdk2 均可通过细胞周期依赖性方式磷酸化 Chk1。Cdk 介导的磷酸化对于 Chk1 的有效激活以及对 DNA 损伤做出反应的检查点功能至关重要。在这里，我们证明 Cdk 介导的磷酸化对于复制应激诱导的 Chk1 激活和 S/M 检查点功能也很重要。将 Chk1 突变体（S286A/S301A）重新引入 Chk1 缺陷细胞中，能够阻止完全未复制 DNA 的细胞进入有丝分裂，但在细胞周期的后期，有丝分裂延迟则受到严重影响。该突变强烈削弱了阿非迪霉素诱导的 Chk1 激活，而不改变 S 期依赖性的 Chk1 激活。这些数据表明，Cdk 介导的磷酸化对于 Chk1 的有效激活和多个检查点功能至关重要。
