State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.
University of Chinese Academy of Sciences, Beijing, China.
FASEB J. 2022 Mar;36(3):e22210. doi: 10.1096/fj.202101586RR.
Precise regulation of chromosome separation through spindle assembly checkpoint (SAC) during oocyte meiosis is critical for mammalian reproduction. The kinetochore plays an important role in the regulation of SAC through sensing microtubule tension imbalance or missing microtubule connections. Here, we report that kinetochore scaffold 1 (KNL1, also known as CASC5), an outer kinetochore protein, plays a critical role in the SAC function of mouse oocytes. KNL1 localized at kinetochores from GVBD to the MII stage, and microinjection of KNL1-siRNA caused accelerated metaphase-anaphase transition and premature first meiosis completion, producing aneuploid eggs. The SAC was prematurely silenced in the presence of unstable kinetochore-microtubule attachments and misaligned chromosomes in KNL1-depleted oocytes. Additionally, KNL1 and MPS1 had a synergistic effect on the activation and maintenance of SAC. Taken together, our results suggest that KNL1, as a kinetochore platform protein, stabilizes SAC to ensure timely anaphase entry and accurate chromosome segregation during oocyte meiotic maturation.
精确调控卵母细胞减数分裂过程中的纺锤体组装检查点（SAC）对于哺乳动物的生殖至关重要。着丝粒通过感知微管张力失衡或缺失微管连接，在 SAC 的调控中发挥着重要作用。在这里，我们报道了着丝粒支架蛋白 1（KNL1，也称为 CASC5）作为一种外着丝粒蛋白，在小鼠卵母细胞的 SAC 功能中发挥着关键作用。KNL1 从 GVBD 到 MII 期定位于着丝粒上，而 KNL1-siRNA 的显微注射导致中期-后期过渡加速，第一次减数分裂过早完成，产生非整倍体卵子。在不稳定的着丝粒-微管连接和染色体错位的情况下，SAC 在 KNL1 耗尽的卵母细胞中被过早沉默。此外，KNL1 和 MPS1 对 SAC 的激活和维持具有协同作用。综上所述，我们的研究结果表明，KNL1 作为着丝粒平台蛋白，稳定 SAC 以确保卵母细胞减数分裂成熟过程中适时进入后期和准确的染色体分离。
