p35, the neuronal-specific activator of cyclin-dependent kinase 5 (Cdk5) is degraded by the ubiquitin-proteasome pathway
p35, the neuronal-specific activator of cyclin-dependent kinase 5 (Cdk5) is degraded by the ubiquitin-proteasome pathway
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DOI：
10.1074/jbc.273.37.24057
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发表时间：
1998-09-11
影响因子：
4.8
通讯作者：
Tsai, LH
中科院分区：
文献类型：
--
作者：
Patrick, GN;Zhou, PB;Tsai, LH
细胞周期蛋白依赖性激酶5 （Cyclin-dependent kinase 5, Cdk5）最初被发现与人类CDC2基因有密切的同源性，而CDC2基因是细胞周期进程的关键调节因子。然而，与其他Cdks不同，Cdk5的活性在有丝分裂后的神经元中是必需的。神经元特异性的p35蛋白，与细胞周期蛋白没有同源性，通过与Cdk5的关联和激活而被发现，小鼠基因靶向研究表明，p35/Cdk5激酶是哺乳动物皮层正常神经元迁移和发育所必需的。我们研究了p35/Cdk5激酶的调控，这里我们发现p35， Cdk5的激活剂，是一种半衰期为20至30分钟的短寿命蛋白。特异性蛋白酶体抑制剂如乳酸蛋白酶素在体内极大地稳定了p35， p35的泛素化可以很容易地在体内和体外证明。特异性Cdk抑制剂罗斯科维汀或显性Cdk5负突变体过表达抑制Cdk5活性可使p35的稳定性提高2- 3倍。此外，p35的磷酸化突变体也能使p35稳定2- 3倍。总之，这些观察结果表明，p35/Cdk5激酶在体内可能会发生快速的周转，并表明Cdk5激酶激活时p35的磷酸化在泛素介导的蛋白水解介导的p35降解中起着自调节作用。
Cyclin-dependent kinase 5 (Cdk5) was originally isolated by its close homology to the human CDC2 gene, which is a key regulator of cell cycle progression. However, unlike other Cdks, the activity of Cdk5 is required in post-mitotic neurons. The neuronal-specific p35 protein, which shares no homology to cyclins, was identified by virtue of its association and activation of Cdk5, Gene targeting studies in mice have shown that the p35/Cdk5 kinase is required for the proper neuronal migration and development of the mammalian cortex, We have investigated the regulation of the p35/Cdk5 kinase, Here we show that p35, the activator of Cdk5, is a short-lived protein with a half-life (t(1/2)) of 20 to 30 min. Specific proteasome inhibitors such as lactacystin greatly stabilize p35 in vivo, Ubiquitination of p35 can be readily demonstrated in vitro and in vivo. Inhibition of Cdk5 activity by a specific Cdk inhibitor, roscovitine, or by overexpression of a dominant negative mutant of Cdk5 increases the stability of p35 by 2- to 3-fold. Furthermore, phosphorylation mutants of p35 also stabilize p35 2- to 3-fold. Together, these observations demonstrate that the p35/Cdk5 kinase can be subject to rapid turnover in vivo and suggest that phosphorylation of p35 upon Cdk5 kinase activation plays a autoregulatory role in p35 degradation mediated by ubiquitin-mediated proteolysis.