Zhang Zixiao, Chen Changchao, Ma Liying, Yu Qiuchen, Li Shuai, Abbasi Benazir, Yang Jiayi, Rui Rong, Ju Shiqiang
College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China.
Nanjing Foreign Languages School, Nanjing, 210008, China.
Reprod Biol Endocrinol. 2017 Aug 29;15(1):69. doi: 10.1186/s12958-017-0289-7.
Polo-like kinase 1 (Plk1), as a characteristic regulator in meiosis, organizes multiple biological events of cell division. Although Plk1 has been implicated in various functions in somatic cell mitotic processes, considerably less is known regarding its function during the transition from metaphase I (MI) to metaphase II (MII) stage in oocyte meiotic progression.
In this study, the possible role of Plk1 during the MI-to-MII stage transition in pig oocytes was addressed. Initially, the spatiotemporal expression and subcellular localization pattern of Plk1 were revealed in pig oocytes from MI to MII stage using indirect immunofluorescence and confocal microscopy imaging techniques combined with western blot analyses. Moreover, a highly selective Plk1 inhibitor, GSK461364, was used to determine the potential role of Plk1 during this MI-to-MII transition progression.
Upon expression, Plk1 exhibited a specific dynamic intracellular localization, and co-localization of Plk1 with α-tubulin was revealed in the meiotic spindle of pig oocyte during the transition from MI to MII stage. GSK461364 treatment significantly blocked the first polar body (pbI) emission in a dose-dependent manner and resulted in a failure of meiotic maturation, with a larger percentage of the GSK461364-treated oocytes arresting in the anaphase-telophase I (ATI) stage. Further subcellular structure examination results showed that inhibition of Plk1 with GSK461364 had no visible effect on spindle assembly but caused a significantly higher proportion of the treated oocytes to have obvious defects in homologous chromosome segregation at ATI stage.
Thus, these results indicate that Plk1 plays an essential role during the meiosis I/meiosis II transition in porcine oocytes, and the regulation is associated with Plk1's effects on homologous chromosome segregation in the ATI stage.
Polo样激酶1（Plk1）作为减数分裂中的一种特征性调节因子，参与细胞分裂的多个生物学事件。尽管Plk1在体细胞有丝分裂过程中具有多种功能，但其在卵母细胞减数分裂进程中从减数第一次分裂中期（MI）到减数第二次分裂中期（MII）阶段的功能却知之甚少。
在本研究中，探讨了Plk1在猪卵母细胞从MI到MII阶段转变过程中的可能作用。首先，运用间接免疫荧光和共聚焦显微镜成像技术结合蛋白质免疫印迹分析，揭示了猪卵母细胞从MI到MII阶段Plk1的时空表达及亚细胞定位模式。此外，使用一种高度选择性的Plk1抑制剂GSK461364来确定Plk1在从MI到MII转变过程中的潜在作用。
表达后，Plk1呈现出特定的动态细胞内定位，并且在猪卵母细胞从MI到MII阶段的减数分裂纺锤体中发现Plk1与α-微管蛋白共定位。GSK461364处理以剂量依赖性方式显著阻断了第一极体（pbI）的排出，并导致减数分裂成熟失败，较大比例的经GSK461364处理的卵母细胞停滞在后期-末期I（ATI）阶段。进一步的亚细胞结构检查结果表明，用GSK461364抑制Plk1对纺锤体组装没有明显影响，但导致处理后的卵母细胞在ATI阶段同源染色体分离出现明显缺陷的比例显著更高。
因此，这些结果表明Plk1在猪卵母细胞减数第一次分裂/减数第二次分裂转变过程中起关键作用，并且这种调节与Plk1在ATI阶段对同源染色体分离的影响有关。
