Role for cyclin-dependent kinase 2 in mitosis exit
Role for cyclin-dependent kinase 2 in mitosis exit
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DOI：
10.1016/s0960-9822(01)00352-9
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发表时间：
2001-08-07
期刊：
影响因子：
9.2
通讯作者：
Grieco, D
中科院分区：
文献类型：
--
作者：
D'Angiolella, V;Costanzo, V;Grieco, D
有丝分裂需要细胞周期蛋白依赖性激酶（cdk）1-细胞周期蛋白B活性[1]。退出有丝分裂依赖于细胞周期蛋白B的降解使复合物失活[2]。Cdk 2在有丝分裂期间也是活跃的[3，4]。在非洲爪蟾卵提取物中，cdk 2主要与细胞周期蛋白E复合，细胞周期蛋白E是稳定的[5]。在有丝分裂结束时，cdk 2-细胞周期蛋白E活性的下调伴随着cdk 2的抑制性磷酸化[6]。在这里，我们表明，cdk 2-细胞周期蛋白E活性维持cdk 1-细胞周期蛋白B在有丝分裂。在有丝分裂退出时，cdk 2先于cdk 1失活。cdk 2活性的丧失遵循并取决于蛋白激酶A（PKA）活性的增加。预处理使cdk 2失活使cyclin B降解和cdk 1失活的时间提前。相反，阻断PKA可稳定cdk 2活性，抑制细胞周期蛋白B降解和cdk 1失活。cdk 1-细胞周期蛋白B的稳定性也由对抑制性磷酸化有抗性的突变cdk 2-细胞周期蛋白E复合物诱导。P21-Cip 1抑制野生型和突变型cdk 2-cyclin E，在任一条件下逆转有丝分裂停滞。我们的研究结果表明，在有丝分裂结束的cdk 2活性的蛋白水解独立下调依赖于PKA，并需要激活蛋白水解级联反应，导致有丝分裂退出。
Mitosis requires cyclin-dependent kinase (cdk) 1-cyclin B activity [1]. Exit from mitosis depends on the inactivation of the complex by the degradation of cyclin B [2]. Cdk2 is also active during mitosis [3, 4]. In Xenopus egg extracts, cdk2 is primarily in complex with cyclin E, which is stable [5]. At the end of mitosis, downregulation of cdk2-cyclin E activity is accompanied by inhibitory phosphorylation of cdk2 [6]. Here, we show that cdk2-cyclin E activity maintains cdk1-cyclin B during mitosis. At mitosis exit, cdk2 is inactivated prior to cdk1. The loss of cdk2 activity follows and depends upon an increase in protein kinase A (PKA) activity. Prematurely inactivating cdk2 advances the time of cyclin B degradation and cdk1 inactivation. Blocking PKA, instead, stabilizes cdk2 activity and inhibits cyclin B degradation and cdk1 inactivation. The stabilization of cdk1-cyclin B is also induced by a mutant cdk2-cyclin E complex that is resistant to inhibitory phosphorylation. P21-Cip1, which inhibits both wild-type and mutant cdk2-cyclin E, reverses mitotic arrest under either condition. Our findings indicate that the proteolysis-independent downregulation of cdk2 activity at the end of mitosis depends on PKA and is required to activate the proteolysis cascade that leads to mitosis exit.