Ca2+-promoted cyclin B1 degradation in mouse oocytes requires the establishment of a metaphase arrest
Ca2+-promoted cyclin B1 degradation in mouse oocytes requires the establishment of a metaphase arrest
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DOI：
10.1016/j.ydbio.2004.01.030
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发表时间：
2004-05-01
影响因子：
2.7
通讯作者：
Jones, KT
中科院分区：
文献类型：
--
作者：
Hyslop, LA;Nixon, VL;Jones, KT
CDK 1-细胞周期蛋白B1是一种通用的细胞周期激酶，需要有丝分裂/减数分裂细胞周期的进入和有丝分裂/减数分裂退出其活性需要下降。在小鼠卵母细胞成熟过程中，它们进行减数分裂I，并在第二次减数分裂中期停滞，具有高的CDK 1-cyclin B1活性。减数分裂停滞是通过细胞生长抑制因子（CSF）的作用实现的，其减少细胞周期蛋白B1的降解。减数分裂停滞被来自精子的Ca 2+信号打破，加速了减数分裂。在这里，我们观察了卵母细胞中细胞周期蛋白B1：：GFP的降解，发现它的降解速率在两次减数分裂中是相同的。Ca 2+是第11次减数分裂中cyclin B1破坏的必要和充分的触发剂，但在第I次减数分裂中不起作用，也不能加速cyclin B I的破坏。Ca 2+的能力，触发细胞周期蛋白B1的破坏开发的卵母细胞后，细胞周期蛋白B1的水平在约12小时的文化重新稳定。这与实际的第一极体挤出无关。因此，在中期I停滞的卵母细胞中，Ca ~（2+）将诱导cyclin B1破坏，第一极体将被挤出。与一些低等物种的报道相反，我们没有发现卵母细胞激活与26 S蛋白酶体活性增加相关的证据。因此，我们得出结论，Ca 2+介导的细胞周期蛋白B1的降解，通过增加E3泛素连接酶的活性。然而，这种刺激仅在泛素连接酶抑制剂CSF存在下发生。我们提出了一个模型，其中Ca 2+直接刺激哺乳动物受精过程中的CSF的破坏。(C)2004年爱思唯尔公司All rights reserved.
CDK1-cyclin B1 is a universal cell cycle kinase required for mitotic/meiotic cell cycle entry and its activity needs to decline for mitotic/ meiotic exit. During their maturation, mouse oocytes proceed through meiosis I and arrest at second meiotic metaphase with high CDK1-cyclin B1 activity. Meiotic arrest is achieved by the action of a cytostatic factor (CSF), which reduces cyclin B1 degradation. Meiotic arrest is broken by a Ca2+ signal from the sperm that accelerates it. Here we visualised degradation of cyclin B1 :: GFP in oocytes and found that its degradation rate was the same for both meiotic divisions. Ca2+ was the necessary and sufficient trigger for cyclin B1 destruction during meiosis 11; but it played no role during meiosis I and furthermore could not accelerate cyclin B I destruction during this time. The ability of Ca2+ to trigger cyclin B1 destruction developed in oocytes following a restabilisation of cyclin B1 levels at about 12 h of culture. This was independent of actual first polar body extrusion. Thus, in metaphase I arrested oocytes, Ca2+ would induce cyclin B1 destruction and the first polar body would be extruded. In contrast to some reports in lower species, we found no evidence that oocyte activation was associated with an increase in 26S proteasome activity. We therefore conclude that Ca2+ mediates cyclin B1 degradation by increasing the activity of an E3 ubiquitin ligase. However, this stimulation occurs only in the presence of the ubiquitin ligase inhibitor CSF. We propose a model in which Ca2+ directly stimulates destruction of CSF during mammalian fertilisation. (C) 2004 Elsevier Inc. All rights reserved.