a Institute of Stem Cell and Regenerative Biology, College of Animal Science and Technology & College of Veterinary Medicine, Huazhong Agricultural University , Wuhan , Hubel , China.
b Key Laboratory of Agricultural Animal Genetics , Breeding and Reproduction (Huazhong Agricultural University), Ministry of Education , Wuhan , Hubel , China.
Cell Cycle. 2017;16(22):2220-2229. doi: 10.1080/15384101.2017.1373221. Epub 2017 Sep 21.
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 Chk1 during porcine oocyte maturation. Chk1 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). Chk1 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, Chk1 overexpression delayed GVBD. These results demonstrated that Chk1 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（Chk1）作为 DNA 复制检验点和 DNA 损伤反应的重要成员，在有丝分裂 G2/M 期发挥着重要作用。本研究以猪卵母细胞为模型，研究 Chk1 在猪卵母细胞成熟过程中的功能。Chk1 从生发泡（GV）到 MII 期表达，主要定位于 GV 期的细胞质中，在 GV 破裂（GVBD）后移至纺锤体。Chk1 耗竭不仅诱导卵母细胞停滞在 MI 期，染色体排列异常，而且抑制 Cyclin B1 的降解，降低纺锤体组装检查点（SAC）蛋白之一 Mad2L1 和激活后期促进复合物/周期蛋白（APC/C）的共激活因子之一钙黏蛋白 1（Cdh1）的表达。此外，Chk1 的过表达延迟了 GVBD。这些结果表明，Chk1 促进了 Cyclin B1 在第一次减数分裂后期 I（AI）的及时降解，并维持了 Mad2L1 和 Cdh1 的表达，从而确保所有染色体都准确地排列在一条直线上，然后卵母细胞通过第一次减数分裂中期 I（MI）和 AI，并成功退出第一次减数分裂。此外，我们证明 Chk1 对猪卵母细胞的 GVBD 没有作用，这表明猪卵母细胞的成熟不需要 DNA 损伤检查点，这与小鼠卵母细胞成熟不同。
