Dynamics of maturation-promoting factor and its constituent proteins during in vitro maturation of bovine oocytes.
Dynamics of maturation-promoting factor and its constituent proteins during in vitro maturation of bovine oocytes.
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DOI：
10.1095/biolreprod56.1.253
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发表时间：
1997
影响因子：
3.6
通讯作者：
Bin Wu;G. Ignotz;W. Bruce Currie;Xiangzhong Yang
中科院分区：
文献类型：
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作者：
Bin Wu;G. Ignotz;W. Bruce Currie;Xiangzhong Yang
成熟促进因子（MPF）是有丝分裂和减数分裂细胞周期的关键调控因子。MPF是B细胞周期蛋白和细胞周期蛋白依赖性激酶cdkl （p34cdc2）的复合物。卵母细胞的成熟及其在减数分裂II （MII）中期的停滞受MPF活性变化的调控。本研究通过实验研究了牛卵母细胞体外成熟过程中MPF活性及其组成蛋白的动态变化。牛卵母细胞成熟的前8小时内，在生发囊泡阶段表现出相对较低水平的MPF（组蛋白H1激酶）活性。MPF活性随后逐渐增加，在成熟12-14 h（假定为中期I）出现第一个活性高峰，随后在16-18 h（假定为后期和末期）活性突然下降。MPF活动随后增加，在成熟20-24 h （MII期）达到平台期。这种高水平的MPF活性维持了几个小时，但在成熟30小时后逐渐下降，在体外成熟（IVM）培养48小时时几乎检测不到。在每个时间点，单个卵母细胞之间组蛋白H1激酶活性存在显著差异，这可能是由于异步成熟。cdk1丰度在IVM的前8小时逐渐增加，然后保持相对稳定，除了在IVM的18-22小时明显减少。细胞周期蛋白B2水平在培养的最初2小时内迅速升高，并保持到16小时，之后在IVM的18 - 22小时显著降低。然而，细胞周期蛋白B2的从头合成在成熟过程中表现出双相振荡，在心肌梗死和心肌梗死发生前达到峰值。这些结果确定了MPF活性及其各个成分在牛卵母细胞体外成熟过程中的概况。我们得出结论，活性MPF调节牛卵母细胞成熟，并且在成熟过程中发生了细胞周期蛋白B2的重新合成。
Maturation-promoting factor (MPF) is known to be a key regulator of both mitotic and meiotic cell cycles. MPF is a complex of a B cyclin and the cyclin-dependent kinase cdkl (p34cdc2). Oocyte maturation and its arrest at metaphase of meiosis II (MII) are regulated by changes in MPF activity. In this study, experiments were conducted to examine the dynamics of MPF activity and its constituent proteins during in vitro maturation of bovine oocytes. Bovine oocytes displayed relatively low levels of MPF (histone H1 kinase) activity at the germinal vesicle stage during the first 8 h of maturation. MPF activity increased gradually thereafter, and its first peak of activity occurred at 12-14 h of maturation (presumptive metaphase I), which was followed by an abrupt reduction in activity at 16-18 h, during presumptive anaphase and telophase. MPF activity then increased, reaching a plateau at 20-24 h of maturation (MII stage). This high level of MPF activity was maintained for several hours but decreased gradually after 30 h of maturation and became barely detectable by 48 h of in vitro maturation (IVM) culture. At each time point, there was a significant variation among individual oocytes in histone H1 kinase activity, which was probably due to asynchronous maturation. Abundance of cdk1 increased gradually during the first 8 h and then remained relatively constant except for an apparent reduction at 18-22 h of IVM. The level of cyclin B2 increased quickly during the initial 2 h of culture, and this high level was maintained until 16 h, after which a significant reduction was observed between 18 and 22 h of IVM. The de novo synthesis of cyclin B2, however, exhibited a biphasic oscillation during maturation, with peaks before the onset of MI and of MII. These results have defined the profiles of MPF activity and its individual components during bovine oocyte maturation in vitro. We conclude that active MPF regulates bovine oocyte maturation and that de novo synthesis of cyclin B2 occurs during the process of maturation.