a Institut de Biologie Paris Seine (IBPS) , Sorbonne Université , Paris , France.
b CNRS UMR7622 Developmental Biology Lab , Sorbonne Université , Paris , France.
Cell Cycle. 2019 Jul;18(14):1537-1548. doi: 10.1080/15384101.2019.1632139. Epub 2019 Jun 23.
B-type cyclins in association with Cdk1 mediate key steps of mitosis and meiosis, by phosphorylating a plethora of substrates. Progression through the meiotic cell cycle requires the execution of two cell divisions named meiosis I and II without intervening S-phase, to obtain haploid gametes. These two divisions are highly asymmetric in the large oocyte. Chromosome segregation in meiosis I and sister chromatid segregation in meiosis II requires the sharp, switch-like inactivation of Cdk1 activity, which is brought about by degradation of B-type cyclins and counteracting phosphatases. Importantly and contrary to mitosis, inactivation of Cdk1 must not allow S-phase to take place at exit from meiosis I. Here, we describe recent studies on the regulation of translation and degradation of B-type cyclins in mouse oocytes, and how far their roles are redundant or specific, with a special focus on the recently discovered oocyte-specific role of cyclin B3.
B 型细胞周期蛋白与 Cdk1 结合，通过磷酸化大量底物，介导有丝分裂和减数分裂的关键步骤。减数细胞周期的进展需要执行两次细胞分裂，称为减数分裂 I 和减数分裂 II，而没有中间的 S 期，以获得单倍体配子。这两次分裂在大卵母细胞中高度不对称。减数分裂 I 中的染色体分离和减数分裂 II 中的姐妹染色单体分离需要 Cdk1 活性的急剧、开关样失活，这是通过 B 型细胞周期蛋白的降解和拮抗磷酸酶来实现的。重要的是，与有丝分裂相反，Cdk1 的失活不能允许 S 期在减数分裂 I 结束时发生。在这里，我们描述了最近关于 B 型细胞周期蛋白在小鼠卵母细胞中的翻译和降解调控的研究，以及它们的作用在多大程度上是冗余的或特异的，特别关注最近发现的卵母细胞特异性 cyclin B3 作用。
