p31(comet) acts to ensure timely spindle checkpoint silencing subsequent to kinetochore attachment.
p31(comet) acts to ensure timely spindle checkpoint silencing subsequent to kinetochore attachment.
复制标题
DOI：
10.1091/mbc.e11-03-0216
复制
发表时间：
2011-11
影响因子：
3.3
通讯作者：
Sorger PK
中科院分区：
文献类型：
--
作者：
Hagan RS;Manak MS;Buch HK;Meier MG;Meraldi P;Shah JV;Sorger PK
p31comet反对Mad2纺锤体组装检查点蛋白的活动，定位于未附着的着丝点，并且像许多检查点蛋白一样，在该位点快速翻转。p31comet的缺失阻止了细胞及时进入后期，这表明有丝分裂过程需要一个主动的机制来沉默纺锤体检查点。纺锤体组装检查点将后期的开始与染色体-微管附着的完成联系起来，并通过Mad和Bub蛋白与未附着或定向错误染色体的着丝点结合介导。Mad2和BubR1在着丝点和细胞质之间传输，从而将“等待后期”信号传递给后期促进复合体。一般认为，该信号在着丝点与微管结合时自动消散，但研究表明，在诺可达唑诱导的阻滞条件下，p31comet（一种mad2结合蛋白）是有丝分裂过程所必需的。在本文中，我们研究了p31comet在人类和有袋动物细胞正常有丝分裂过程中的定位和功能。我们发现，像Mad2一样，p31comet也能进出着丝点，并且也存在于细胞质中。中期p31comet缺失的细胞具有成熟的双极着丝细胞-微管附着物、满意的检查点和高周期蛋白B水平。因此p31comet是有丝分裂及时退出所必需的。我们认为p31comet是在每个细胞周期中沉默检查点机制的重要组成部分。
p31comet opposes the activities of the Mad2 spindle assembly checkpoint protein, localizes to unattached kinetochores, and like many checkpoint proteins, turns over rapidly at that site. Depletion of p31comet prevents timely passage into anaphase, showing that mitotic progression requires an active mechanism for silencing the spindle checkpoint. The spindle assembly checkpoint links the onset of anaphase to completion of chromosome-microtubule attachment and is mediated by the binding of Mad and Bub proteins to kinetochores of unattached or maloriented chromosomes. Mad2 and BubR1 traffic between kinetochores and the cytosol, thereby transmitting a “wait anaphase” signal to the anaphase-promoting complex. It is generally assumed that this signal dissipates automatically upon kinetochore-microtubule binding, but it has been shown that under conditions of nocodazole-induced arrest p31comet, a Mad2-binding protein, is required for mitotic progression. In this article we investigate the localization and function of p31comet during normal, unperturbed mitosis in human and marsupial cells. We find that, like Mad2, p31comet traffics on and off kinetochores and is also present in the cytosol. Cells depleted of p31comet arrest in metaphase with mature bipolar kinetochore-microtubule attachments, a satisfied checkpoint, and high cyclin B levels. Thus p31comet is required for timely mitotic exit. We propose that p31comet is an essential component of the machinery that silences the checkpoint during each cell cycle.