The requirements for protein synthesis and degradation, and the control of destruction of cyclins A and B in the meiotic and mitotic cell cycles of the clam embryo.
The requirements for protein synthesis and degradation, and the control of destruction of cyclins A and B in the meiotic and mitotic cell cycles of the clam embryo.
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DOI：
10.1083/jcb.116.3.707
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发表时间：
1992-02
期刊：
影响因子：
--
通讯作者：
Ruderman JV
中科院分区：
文献类型：
--
作者：
Hunt T;Luca FC;Ruderman JV
蛤卵母细胞受精后开始一系列的细胞分裂，其中前三次——减数分裂I、减数分裂II和第一次有丝分裂——是高度同步的。受精后，除减数分裂I外，每一个分裂的成功完成都需要蛋白质的合成。当蛋白质合成受到抑制时，进入减数分裂I和维持减数分裂正常持续时间的M期正常发生，但染色体在减数分裂II中期不能与纺锤体正确相互作用。相反，在完成减数分裂或有丝分裂后立即抑制蛋白质合成会阻止细胞进入下一个有丝分裂。我们描述了周期蛋白A和B的行为与这些“不归点”的关系。细胞周期蛋白是连续合成的，并在有丝分裂细胞周期中期-后期转变之前迅速被破坏，细胞周期蛋白A在细胞周期蛋白B之前被降解。细胞周期蛋白的破坏通常发生在有丝分裂的5分钟窗口期，但在蛤卵孤雌活化后发生的单极有丝分裂中，或当秋水仙碱加入到即将进入第一次有丝分裂的受精卵中时，细胞周期蛋白B的破坏被强烈延迟。而细胞周期蛋白A的蛋白水解在中期停滞期间维持在激活状态。在上述任何一种异常情况下，抑制蛋白质合成都会导致细胞过早回到与细胞周期蛋白B消失时间相关的间期。
Fertilization of clam oocytes initiates a series of cell divisions, of which the first three--meiosis I, meiosis II, and the first mitotic division--are highly synchronous. After fertilization, protein synthesis is required for the successful completion of every division except meiosis I. When protein synthesis is inhibited, entry into meiosis I and the maintenance of M phase for the normal duration of meiosis occur normally, but the chromosomes fail to interact correctly with the spindle in meiosis II metaphase. By contrast, inhibition of protein synthesis immediately after completion of meiosis or mitosis stops cells entering the next mitosis. We describe the behavior of cyclins A and B in relation to these "points of no return." The cyclins are synthesized continuously and are rapidly destroyed shortly before the metaphase-anaphase transition of the mitotic cell cycles, with cyclin A being degraded in advance of cyclin B. Cyclin destruction normally occurs during a 5-min window in mitosis, but in the monopolar mitosis that occurs after parthenogenetic activation of clam oocytes, or when colchicine is added to fertilized eggs about to enter first mitosis, the destruction of cyclin B is strongly delayed, whereas proteolysis of cyclin A is maintained in an activated state for the duration of metaphase arrest. Under either of these abnormal conditions, inhibition of protein synthesis causes a premature return to interphase that correlates with the time when cyclin B disappears.