Lay Khin Mar, Oshiro Ryuko, Arasaki Chiemi, Ashizawa Koji, Tatemoto Hideki
Science of Bioresource Production, The United Graduate School of Agricultural Sciences, Kagoshima University, Kagoshima 890-0065, Japan.
J Reprod Dev. 2011 Dec;57(6):744-51. doi: 10.1262/jrd.11-057h. Epub 2011 Sep 6.
The porcine zona pellucida (ZP) undergoes biochemical changes during the final phase of maturation prior to fertilization. The present study was conducted to elucidate whether the acidification of ZP glycoproteins during porcine oocyte maturation influences sperm-ZP interactions. Two-dimensional gel electrophoresis clearly demonstrated that ZP acidification occurred in accordance with the sialylation and sulfation of ZP glycoproteins in oocytes matured for 44 h. The increases in the incidences of sperm penetration and polyspermy with the progress of the IVM culture period were significantly suppressed by ZP desialylation on treatment with neuraminidase as a consequence of reductions in the number of sperm bound to ZPs and the acrosome reaction (AR) in ZP-bound sperm (P<0.05). In contrast, the blocking of ZP sulfation by NaClO(3) treatment during IVM markedly reduced the incidence of polyspermy with no inhibitory effect on penetration, but the number of sperm bound to ZPs and the rate of AR-inducing sperm were decreased to the same level as in desialylated oocytes. The results indicate that ZP sulfation influences sperm-ZP interactions in a ZP sialylation-independent manner. Moreover, sialylation and sulfation were not associated with a protective proteolytic modification of the ZP matrix before fertilization. These findings suggest that ZP acidification elicited by the sialylation and sulfation of ZP glycoproteins during oocyte maturation contributes to the porcine ZP acquiring the capacity to accept sperm.
猪透明带（ZP）在受精前成熟的最后阶段会发生生化变化。本研究旨在阐明猪卵母细胞成熟过程中ZP糖蛋白的酸化是否会影响精子与ZP的相互作用。二维凝胶电泳清楚地表明，在体外成熟培养44小时的卵母细胞中，ZP酸化与ZP糖蛋白的唾液酸化和硫酸化同时发生。用神经氨酸酶处理使ZP去唾液酸化后，随着体外成熟培养时间的延长，精子穿透率和多精受精率的增加受到显著抑制，这是由于与ZP结合的精子数量减少以及ZP结合精子中的顶体反应（AR）减少所致（P<0.05）。相反，在体外成熟过程中用NaClO(3)处理阻断ZP硫酸化，显著降低了多精受精率，但对精子穿透没有抑制作用，不过与ZP结合的精子数量和诱导AR的精子比率降低到了与去唾液酸化卵母细胞相同的水平。结果表明，ZP硫酸化以不依赖于ZP唾液酸化的方式影响精子与ZP的相互作用。此外，唾液酸化和硫酸化与受精前ZP基质的保护性蛋白水解修饰无关。这些发现表明，卵母细胞成熟过程中ZP糖蛋白的唾液酸化和硫酸化引发的ZP酸化有助于猪ZP获得接受精子的能力。
