Wang Qiao-Chu, Liu Jun, Wang Zhen-Bo, Zhang Yu, Duan Xing, Cui Xiang-Shun, Kim Nam-Hyung, Sun Shao-Chen
College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, 210095, China.
Biol Cell. 2014 Jun;106(6):193-202. doi: 10.1111/boc.201400007. Epub 2014 May 12.
During meiosis, a bipolar spindle forms in the central cytoplasm of an oocyte and then moves to the cortex to extrude the first polar body. This is dependent on the regulation of actin and actin-related molecules. Dynamin 2, a large guanosine triphosphatases (GTPase) known to regulate clathrin-mediated endocytosis, is involved in actin recruitment and actin-based vesicle mobility. In this study, we investigated the role of Dynamin 2 in oocyte meiosis.
Dynamin 2 was localised at the cortex and around the spindles of oocytes. Disrupting Dynamin 2 activity by RNAi or an inhibitor resulted in polar body extrusion failure. Using time-lapse microscopy to monitor aberrant oocyte cytokinesis, the chromosomes were first separated, but then re-joined. Actin expression in oocytes was decreased; and actin cap formation was disrupted, which was confirmed by the disappearance of cortical-granule-free domains. In addition, live cell imaging showed that spindle migration had failed and that spindles were arrested centrally in oocytes. This may have been due to the Dynamin-binding protein Profilin and actin-related protein 2/3 (ARP2/3) complexes, which exhibited dispersed signals after disrupting Dynamin 2 activity.
Thus, our results indicate that Dynamin 2 regulates spindle migration and polar body extrusion during mouse oocyte meiosis through an actin-based pathway.
在减数分裂过程中，双极纺锤体在卵母细胞的中央细胞质中形成，然后移动到皮质以排出第一极体。这依赖于肌动蛋白和肌动蛋白相关分子的调节。发动蛋白2是一种已知可调节网格蛋白介导的内吞作用的大型鸟苷三磷酸酶（GTPase），参与肌动蛋白募集和基于肌动蛋白的囊泡移动。在本研究中，我们研究了发动蛋白2在卵母细胞减数分裂中的作用。
发动蛋白2定位于卵母细胞的皮质和纺锤体周围。通过RNA干扰或抑制剂破坏发动蛋白2的活性会导致极体排出失败。使用延时显微镜监测异常的卵母细胞胞质分裂，染色体首先分离，但随后重新结合。卵母细胞中的肌动蛋白表达降低；并且肌动蛋白帽形成被破坏，这通过无皮质颗粒区域的消失得到证实。此外，活细胞成像显示纺锤体迁移失败，纺锤体在卵母细胞中央停滞。这可能是由于发动蛋白结合蛋白丝切蛋白和肌动蛋白相关蛋白2/3（ARP2/3）复合物，在破坏发动蛋白2活性后表现出分散的信号。
因此，我们的结果表明，发动蛋白2在小鼠卵母细胞减数分裂过程中通过基于肌动蛋白的途径调节纺锤体迁移和极体排出。
