Li Jian, Zhang Hong-Yong, Wang Feng, Sun Qing-Yuan, Qian Wei-Ping
Department of Reproductive Medicine, Peking University Shenzhen Hospital, Shenzhen Peking University-The Hong Kong University of Science and Technology Medical Center, Shenzhen, China.
State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.
Front Cell Dev Biol. 2021 Mar 11;9:648053. doi: 10.3389/fcell.2021.648053. eCollection 2021.
Recently, we have reported that the cyclin B2/CDK1 complex regulates homologous chromosome segregation through inhibiting separase activity in oocyte meiosis I, which further elucidates the compensation of cyclin B2 on cyclin B1's function in meiosis I. However, whether cyclin B2/CDK1 complex also negatively regulates separase activity during oocyte meiosis II remains unknown. In the present study, we investigated the function of cyclin B2 in meiosis II of oocyte. We found that stable cyclin B2 expression impeded segregation of sister chromatids after oocyte parthenogenetic activation. Consistently, stable cyclin B2 inhibited separase activation, while introduction of non-phosphorylatable separase mutant rescued chromatid separation in the stable cyclin B2-expressed oocytes. Therefore, the cyclin B2/CDK1 complex conservatively regulates separase activity inhibitory phosphorylation of separase in both meiosis I and meiosis II of mouse oocyte.
最近，我们报道了细胞周期蛋白B2/细胞周期蛋白依赖性激酶1（Cyclin B2/CDK1）复合物通过抑制卵母细胞减数分裂I中的分离酶活性来调节同源染色体分离，这进一步阐明了细胞周期蛋白B2对细胞周期蛋白B1在减数分裂I中功能的补偿作用。然而，细胞周期蛋白B2/CDK1复合物在卵母细胞减数分裂II期间是否也负向调节分离酶活性仍不清楚。在本研究中，我们研究了细胞周期蛋白B2在卵母细胞减数分裂II中的功能。我们发现，稳定的细胞周期蛋白B2表达会阻碍卵母细胞孤雌激活后姐妹染色单体的分离。同样，稳定的细胞周期蛋白B2抑制分离酶的激活，而引入不可磷酸化的分离酶突变体则挽救了稳定表达细胞周期蛋白B2的卵母细胞中的染色单体分离。因此，细胞周期蛋白B2/CDK1复合物在小鼠卵母细胞的减数分裂I和减数分裂II中保守地调节分离酶活性——对分离酶进行抑制性磷酸化。
