Function and regulation mechanism of <i>Chk1</i> during meiotic maturation in porcine oocytes

Checkpoint 1 (Chk1), as an important member of DNA replication checkpoint and DNA damage response, has an important role during the G2/M stage of mitosis. In this study, we used porcine oocyte as a model to investigate the function of <i>Chk1</i> during porcine oocyte maturation. <i>Chk1</i> was expressed from germinal vesicle (GV) to metaphase II (MII) stages, mainly localized in the cytoplasm at GV stage and moved to the spindle after germinal vesicle breakdown (GVBD). <i>Chk1</i> depletion not only induced oocytes to be arrested at MI stage with abnormal chromosomes arrangement, but also inhibited the degradation of Cyclin B1 and decreased the expression of Mitotic Arrest Deficient 2-Like 1 (Mad2L1), one of spindle assembly checkpoint (SAC) proteins, and cadherin 1 (Cdh1), one of coactivation for anaphase-promoting complex/cyclosome (APC/C). Moreover, <i>Chk1</i> overexpression delayed GVBD. These results demonstrated that <i>Chk1</i> facilitated the timely degradation of Cyclin B1 at anaphase I (AI) and maintained the expression of Mad2L1 and Cdh1, which ensured that all chromosomes were accurately located in a line, and then oocytes passed metaphase I (MI) and AI and exited from the first meiotic division successfully. In addition, we proved that Chk1 had not function on GVBD of porcine oocytes, which suggested that maturation of porcine oocytes did not need the DNA damage checkpoint, which was different from the mouse oocyte maturation.

检验点激酶1（Checkpoint 1, Chk1）作为DNA复制检验点与DNA损伤应答的重要成员，在有丝分裂G2/M期发挥关键调控作用。本研究以猪卵母细胞为实验模型，探究Chk1在猪卵母细胞成熟过程中的功能。Chk1的表达覆盖从生发泡（germinal vesicle, GV）期至第二次减数分裂中期（metaphase II, MII）的各个阶段，在GV期主要定位于细胞质，于生发泡破裂（germinal vesicle breakdown, GVBD）后转移至纺锤体结构。敲低Chk1不仅会诱导卵母细胞停滞于第一次减数分裂中期（metaphase I, MI）并出现染色体排列异常，还会抑制细胞周期蛋白B1（Cyclin B1）的降解，并降低纺锤体组装检验点（spindle assembly checkpoint, SAC）蛋白成员有丝分裂后期阻滞缺陷2样1（Mitotic Arrest Deficient 2-Like 1, Mad2L1）以及后期促进复合物/周期体（anaphase-promoting complex/cyclosome, APC/C）共激活因子钙粘蛋白1（cadherin 1, Cdh1）的表达水平。此外，过表达Chk1会延缓GVBD进程。上述结果表明，Chk1可促进第一次减数分裂后期（anaphase I, AI）细胞周期蛋白B1的及时降解，并维持Mad2L1与Cdh1的表达水平，从而确保所有染色体精准排列于赤道板，使卵母细胞顺利通过MI期与AI期，成功完成第一次减数分裂。此外，本研究证实Chk1并不参与猪卵母细胞的GVBD过程，这提示猪卵母细胞成熟并不依赖DNA损伤检验点通路，该特性与小鼠卵母细胞成熟过程存在显著差异。

搜集汇总

背景与挑战

背景概述

该数据集提供了猪卵母细胞减数分裂成熟过程中Chk1功能和调控机制研究的原始实验数据，包括Chk1的表达、定位及其对染色体排列、Cyclin B1降解等关键过程的影响。研究发现Chk1在猪卵母细胞中不影响GVBD，揭示了与小鼠模型的物种差异，数据集支持相关细胞生物学和遗传学分析。