Regulation of the antioncogenic Chk2 kinase by the oncogenic Wip1 phosphatase
Regulation of the antioncogenic Chk2 kinase by the oncogenic Wip1 phosphatase
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DOI：
10.1038/sj.cdd.4401801
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发表时间：
2006-07-01
影响因子：
12.4
通讯作者：
Minami, Y.
中科院分区：
文献类型：
--
作者：
Fujimoto, H.;Onishi, N.;Minami, Y.
抗癌Chk 2激酶在DNA损伤诱导的细胞周期检查点调控中起着至关重要的作用。在这里，我们表明，Chk 2与致癌蛋白Wip 1（野生型p53诱导型磷酸酶1）（PPM 1D），p53诱导蛋白磷酸酶。Chk 2在苏氨酸68（Thr 68）处的磷酸化是Chk 2激活的关键事件，其通常由DNA损伤或Chk 2的过表达诱导，其被野生型（WT）的表达抑制，但不被培养细胞中Wip 1的磷酸酶缺陷突变体（D314 A）抑制。此外，体外磷酸酶测定显示，Wip 1（WT）而不是Wip 1（D314 A）在体外使磷酸化Chk 2上的Thr 68去磷酸化，导致Chk 2激酶对谷胱甘肽S-转移酶-Cdc 25 C的活性受到抑制。此外，通过RNA干扰抑制Wip 1表达导致Chk 2的Thr 68磷酸化异常持续，并且细胞对DNA损伤的敏感性增加，表明Wip 1作为Chk 2对DNA损伤的负调节剂起作用。
The antioncogenic Chk2 kinase plays a crucial role in DNA damage-induced cell-cycle checkpoint regulation. Here we show that Chk2 associates with the oncogenic protein Wip1 (wild-type p53-inducible phosphatase 1) (PPM1D), a p53-inducible protein phosphatase. Phosphorylation of Chk2 at threonine68 (Thr68), a critical event for Chk2 activation, which is normally induced by DNA damage or overexpression of Chk2, is inhibited by expression of wild-type (WT), but not a phosphatase-deficient mutant (D314A) of Wip1 in cultured cells. Furthermore, an in vitro phosphatase assay revealed that Wip1 ( WT), but not Wip1 (D314A), dephosphorylates Thr68 on phosphorylated Chk2 in vitro, resulting in the inhibition of Chk2 kinase activity toward glutathione S-transferase-Cdc25C. Moreover, inhibition of Wip1 expression by RNA interference results in abnormally sustained Thr68 phosphorylation of Chk2 and increased susceptibility of cells in response to DNA damage, indicating that Wip1 acts as a negative regulator of Chk2 in response to DNA damage.