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Updated: May 22, 2026

Evaluation of the Spindle Assembly Checkpoint Integrity in Mouse Oocytes
Published on: September 13, 2022
Checkpoint kinase 1 is essential for meiotic cell cycle regulation in mouse oocytes
Lei Chen1, Shi-Bin Chao, Zhen-Bo Wang
1State Key Laboratory of Reproductive Biology, Institute of Zoology; Chinese Academy of Sciences, Beijing, China.
Abstract:
Checkpoint kinase 1 (Chk1) plays key roles in all currently defined cell cycle checkpoints, but its functions in mouse oocyte meiosis remain unclear. In this study, we report the expression, localization and functions of Chk1 in mouse oocyte meiosis. Chk1 was expressed from germinal vesicle (GV) to metaphase II (MII) stages and localized to the spindle from pro-metaphase I (pro-MI) to MII stages in mouse oocytes. Chk1 depletion facilitated the G 2/M transition while Chk1 overexpression inhibited the G 2/M transition as indicated by germinal vesicle breakdown (GVBD), through regulation of Cdh1 and Cyclin B1. Chk1 depletion did not affect meiotic cell cycle progression after GVBD, but its overexpression after GVBD activated the spindle assembly checkpoint and prevented homologous chromosome segregation, thus arresting oocytes at pro-MI or metaphase I (MI) stages. These results suggest that Chk1 is indispensable for prophase I arrest and functions in G 2/M checkpoint regulation in meiotic oocytes. Moreover, Chk1 overexpression affects meiotic spindle assembly checkpoint regulation and thus chromosome segregation.
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