Degradation of cyclin B is required for the onset of anaphase in mammalian cells
Degradation of cyclin B is required for the onset of anaphase in mammalian cells
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DOI：
10.1074/jbc.m306376200
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发表时间：
2003-09-26
影响因子：
4.8
通讯作者：
Luo, KQ
中科院分区：
文献类型：
--
作者：
Chang, DC;Xu, NH;Luo, KQ
最近有研究表明，在哺乳动物细胞中，细胞周期蛋白B1主要在后期开始前被降解。当一种不可降解形式的细胞周期蛋白B1被引入细胞时，中期到后期的转变被阻断。这种阻滞不是由于激活后期促进复合体的失败，也不是由于安全蛋白降解的失败。为了解决过度表达不可降解形式的细胞周期蛋白B1是否与生理相关的问题，我们开发了一种新的方法来估计单个细胞中过度表达的细胞周期蛋白B1突变体的相对蛋白水平。我们发现，低水平的不可降解细胞周期蛋白B1（低于内源性细胞周期蛋白B1的30%）足以阻断中期到后期的转变，这意味着不可降解细胞周期蛋白B1对后期开始的阻断不是由于过度的m期促进因子活性的人为影响。这一结果表明，在哺乳动物细胞中，大部分细胞周期蛋白B1必须在细胞进入后期之前被破坏。
Recently, it has been shown that cyclin B1 was degraded mainly before the onset of anaphase in mammalian cells. When a nondegradable form of cyclin B1 was introduced into cells, the metaphase-anaphase transition was blocked. This blockage was not due to a failure in activating anaphase-promoting complex, nor was it due to a failure of degradation of securin. To resolve the question of whether this blockage by overexpressing the nondegradable form of cyclin B1 is physiologically relevant or not, we developed a novel method to estimate the relative protein level of the overexpressed cyclin B1 mutant within an individual cell. We found that a low level of nondegradable cyclin B1 ( less than 30% of the endogenous cyclin B1) was sufficient to block the metaphase-anaphase transition, implying that the blockage of anaphase onset by the nondegradable cyclin B1 was not due to an artifact of excessive M-phase-promoting factor activity. This result suggests that, in mammalian cells, the majority of cyclin B1 must be destroyed before the cell can enter anaphase.