Yuan Kai, Hu Haiying, Guo Zhen, Fu Guosheng, Shaw Andrew P, Hu Renming, Yao Xuebiao
Division of Cellular Dynamics, Hefei National Laboratory and Chinese University of Science & Technology, Hefei 230027, China; Department of Physiology, Morehouse School of Medicine, Atlanta, Georgia 30310.
Division of Cellular Dynamics, Hefei National Laboratory and Chinese University of Science & Technology, Hefei 230027, China; Department of Endocrinology and Metabolism, Hua Shan Hospital, Fudan University School of Medicine, Shanghai 200040, China, and.
J Biol Chem. 2007 Sep 14;282(37):27414-27423. doi: 10.1074/jbc.M703555200. Epub 2007 Jul 10.
Chromosome segregation in mitosis is orchestrated by dynamic interactions between spindle microtubules and centromeres, which in turn are governed by protein kinase- and phosphatase-signaling cascades. Previous studies showed that overexpression of human phosphatase HsCdc14A, an antagonist of cyclin-dependent kinase 1, affects several aspects of cell division. However, the molecular mechanism underlying HsCdc14A regulation in mitosis has remained elusive. Here we show that HsCdc14A activity is regulated by an auto-inhibitory mechanism via its intra-molecular association. Our biochemical study demonstrated that Polo-like kinase 1 (PLK1) interacts with and phosphorylates HsCdc14A. This phosphorylation partially releases the auto-inhibition of HsCdc14A judged by its phosphatase activity in vitro. To examine the functional relevance of such phospho-regulation of HsCdc14A in vivo, a phospho-mimicking mutant of HsCdc14A was expressed in HeLa cells. Importantly, overexpression of the phospho-mimicking mutants caused aberrant chromosome alignment with a prometaphase delay, suggesting the temporal regulation of HsCdc14A activity is critical for orchestrating mitotic events. Given the fact that HsCdc14A forms an intra-molecular association and PLK1-mediated phospho-regulation promotes HsCdc14A phosphatase activity, we propose that PLK1-HsCdc14A interaction provides a temporal regulation of HsCdc14A in chromosome segregation during mitosis.
有丝分裂中的染色体分离是由纺锤体微管与着丝粒之间的动态相互作用精心编排的，而这些相互作用又受蛋白激酶和磷酸酶信号级联的控制。先前的研究表明，细胞周期蛋白依赖性激酶1的拮抗剂——人磷酸酶HsCdc14A的过表达会影响细胞分裂的多个方面。然而，HsCdc14A在有丝分裂中调控的分子机制仍然不清楚。在这里，我们表明HsCdc14A的活性通过其分子内缔合受一种自抑制机制调控。我们的生化研究表明，Polo样激酶1（PLK1）与HsCdc14A相互作用并使其磷酸化。根据其体外磷酸酶活性判断，这种磷酸化部分解除了HsCdc14A的自抑制。为了在体内研究HsCdc14A这种磷酸化调控的功能相关性，在HeLa细胞中表达了HsCdc14A的磷酸模拟突变体。重要的是，磷酸模拟突变体的过表达导致染色体排列异常并伴有前中期延迟，这表明HsCdc14A活性的时间调控对于协调有丝分裂事件至关重要。鉴于HsCdc14A形成分子内缔合且PLK1介导的磷酸化调控促进HsCdc14A磷酸酶活性，我们提出PLK1-HsCdc14A相互作用在有丝分裂期间对染色体分离中的HsCdc14A提供了时间调控。
