a College of Animal Science and Technology, Nanjing Agricultural University , Nanjing , China.
b Shandong Institute of Pharmaceutical Industry, Shandong Provincial Key Laboratory of Chemical Drugs , Jinan , China.
Cell Cycle. 2017;16(21):2139-2145. doi: 10.1080/15384101.2017.1380133. Epub 2017 Oct 4.
Cytoplasmic dynein is a family of cytoskeletal motor proteins that move towards the minus-end of the microtubules to perform functions in a variety of mitotic processes such as cargo transport, organelle positioning, chromosome movement and centrosome assembly. However, its specific roles during mammalian oocyte meiosis have not been fully defined. Herein, we investigated the critical events during porcine oocyte meiotic maturation after inhibition of dynein by Ciliobrevin D treatment. We found that oocyte meiotic progression was arrested when inhibited of dynein by showing the poor expansion of cumulus cells and decreased rate of polar body extrusion. Meanwhile, the spindle assembly and chromosome alignment were disrupted, accompanied by the reduced level of acetylated α-tubulin, indicative of weakened microtubule stability. Defective actin polymerization on the plasma membrane was also observed in dynein-inhibited oocytes. In addition, inhibition of dynein caused the abnormal distribution of cortical granules and precocious exocytosis of ovastacin, a cortical granule component, which predicts that ZP2, the sperm binding site in the zona pellucida, might be prematurely cleaved in the unfertilized dynein-inhibited oocytes, potentially leading to the fertilization failure. Collectively, our findings reveal that dynein plays a part in porcine oocyte meiotic progression by regulating the cytoskeleton dynamics including microtubule stability, spindle assembly, chromosome alignment and actin polymerization. We also find that dynein mediates the normal cortical granule distribution and exocytosis timing of ovastacin in unfertilized eggs which are the essential for the successful fertilization.
细胞质动力蛋白是一类细胞骨架马达蛋白，它们向微管的负端移动，以在多种有丝分裂过程中发挥作用，如货物运输、细胞器定位、染色体运动和中心体组装。然而，其在哺乳动物卵母细胞减数分裂中的具体作用尚未完全确定。在此，我们通过 Ciliobrevin D 抑制动力蛋白来研究猪卵母细胞减数分裂成熟过程中的关键事件。我们发现，当抑制动力蛋白时，卵母细胞减数分裂进展被阻断，表现为卵丘细胞扩展不良和极体排出率降低。同时，纺锤体组装和染色体排列被打乱，伴随着乙酰化α-微管蛋白水平降低，表明微管稳定性减弱。在动力蛋白抑制的卵母细胞中，也观察到质膜上的肌动蛋白聚合缺陷。此外，动力蛋白的抑制导致皮质颗粒的异常分布和卵黄蛋白原的早熟胞吐作用，卵黄蛋白原是皮质颗粒的一种成分，这表明在未受精的动力蛋白抑制卵母细胞中，透明带中的精子结合位点 ZP2 可能会提前被切割，这可能导致受精失败。总之，我们的研究结果表明，动力蛋白通过调节包括微管稳定性、纺锤体组装、染色体排列和肌动蛋白聚合在内的细胞骨架动力学，在猪卵母细胞减数分裂进展中发挥作用。我们还发现，动力蛋白介导了未受精卵中卵黄蛋白原的正常皮质颗粒分布和胞吐作用的定时，这对于成功受精是必不可少的。
