Mad2 binding by phosphorylated kinetochores links error detection and checkpoint action in mitosis
Mad2 binding by phosphorylated kinetochores links error detection and checkpoint action in mitosis
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DOI：
10.1016/s0960-9822(99)80287-5
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发表时间：
1999-06-17
期刊：
影响因子：
9.2
通讯作者：
Nicklas, RB
中科院分区：
文献类型：
--
作者：
Waters, JC;Chen, RH;Nicklas, RB
纺锤体检查点必须检测未附着或不正确附着的着丝粒的存在，然后必须抑制细胞周期的进展，直到违规条件得到解决。检测可能涉及附着敏感的动粒磷酸化（综述见[1，2]）。检查点反应中的关键参与者是Mad 2蛋白，其防止Cdc 20蛋白激活后期促进复合物（APC）[3-8]，Mad 2抗体的显微注射导致过早的后期开始[9，10]，并且过量的Mad 2蛋白导致有丝分裂停滞[5，11]。我们以前已经证明，Mad 2定位于脊椎动物细胞中未连接的动粒，并且这种定位随着动粒积累微管而停止[10，12，13]，但是Mad 2结合如何限于未连接的动粒？在这里，我们使用裂解的PtK 1细胞来研究动粒磷酸化和Mad 2结合。我们发现Mad 2结合磷酸化的着丝粒，但不结合未磷酸化的。我们的数据表明，这是着丝粒蛋白磷酸化，促进Mad 2结合到未连接的着丝粒。因此，我们已经确定了附着敏感的动粒磷酸化和后期抑制之间可能的分子联系，现在可以概述有丝分裂中错误控制的完整途径。(C)爱思唯尔科学有限公司ISSN 0960-9822。
The spindle checkpoint must detect the presence of unattached or improperly attached kinetochores and must then inhibit progression through the cell cycle until the offending condition is resolved. Detection probably involves attachment-sensitive kinetochore phosphorylation (reviewed in [1,2]). A key player in the checkpoint's response is the Mad2 protein, which prevents activation of the anaphase-promoting complex (APC) by the Cdc20 protein [3-8], Microinjection of Mad2 antibodies results in premature anaphase onset [9,10], and excess Mad2 protein causes arrest in mitosis [5,11]. We have previously shown that Mad2 localizes to unattached kinetochores in vertebrate cells, and that this localization ceases as kinetochores accumulate microtubules [10,12,13], But how is Mad2 binding limited to unattached kinetochores? Here, we used lysed PtK1 cells to study kinetochore phosphorylation and Mad2 binding. We found that Mad2 binds to phosphorylated kinetochores, but not to unphosphorylated ones. Our data suggest that it is kinetochore protein phosphorylation that promotes Mad2 binding to unattached kinetochores. Thus, we have identified a probable molecular link between attachment-sensitive kinetochore phosphorylation and the inhibition of anaphase, The complete pathway for error control in mitosis can now be outlined. (C) Elsevier Science Ltd ISSN 0960-9822.