Cdc25B activity is regulated by 14-3-3
Cdc25B activity is regulated by 14-3-3
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DOI：
10.1038/sj.onc.1204574
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发表时间：
2001-07-19
期刊：
影响因子：
8
通讯作者：
Gabrielli, B
中科院分区：
文献类型：
--
作者：
Forrest, A;Gabrielli, B
在G2期细胞周期检查点停滞中，依赖于CDC25的细胞周期蛋白B/CDC2的激活被阻止，这是调节进入有丝分裂的关键步骤。在酵母中的研究表明，CDC25功能的抑制涉及14-3-3与CDC25的结合，在人类中，两种CDC25亚型都与14-3-3结合，cdc25B和cdc25C都与14-3-3结合，取消14-3-3与CDC25C的结合可以减弱G2检查点抑制，但14-3-3结合对CDC25B功能的调节作用尚不清楚。在这里，我们证明了在G2检查点受阻细胞中高水平过表达cdc25B可以激活Cyclin B/cdc2并克服检查点受阻。主要14-3-3结合位点S323的突变或N-末端调节域的去除是很强的激活突变，提高了cdc25B的突变形式不仅克服了停滞，而且还启动了异常有丝分裂，我们还证明了14-3-3结合到cdc25B上的S323位点阻止了底物细胞周期蛋白/CDKs进入酶的催化部位，从而直接抑制了cdc25B的活性，这为14-3-3与cdc25B结合可以调节其活性，从而控制有丝分裂提供了直接的机制证据。
In the G2 phase cell cycle checkpoint arrest, the cdc25-dependent activation of cyclin B/cdc2, a critical step in regulating entry into mitosis, is blocked. Studies in yeast have demonstrated that the inhibition of cdc25 function involves 14-3-3 binding to cdc25, In humans, two cdc25 isoforms have roles in G2/M progression, cdc25B and cdc25C, both bind 14-3-3, Abrogating 14-3-3 binding to cdc25C attenuates the G2 checkpoint arrest, but the contribution of 14-3-3 binding to the regulation of cdc25B function is unknown. Here we demonstrate that high level over-expression of cdc25B in G2 checkpoint arrested cells can activate cyclin B/cdc2 and overcome the checkpoint arrest. Mutation of the major 14-3-3 binding site, S323, or removal of the N-terminal regulatory domain are strong activating mutations, increasing the efficiency with which the mutant forms of cdc25B not only overcome the arrest, but also initiate aberrant mitosis, We also demonstrate that 14-3-3 binding to the S323 site on cdc25B blocks access of the substrate cyclin/cdks to the catalytic site of the enzyme, thereby directly inhibiting the activity of cdc25B, This provides direct mechanistic evidence that 14-3-3 binding to cdc25B can regulate its activity, thereby controlling progression into mitosis.