Epithelial Cell Biology Research Center, School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China.
Protein Cell. 2011 Feb;2(2):92-8. doi: 10.1007/s13238-011-1022-5. Epub 2011 Mar 5.
Fertilization is a process involving multiple steps that lead to the final fusion of one sperm and the oocyte to form the zygote. One of the steps, acrosome reaction (AR), is an exocytosis process, during which the outer acrosome membrane fuses with the inner sperm membrane, leading to the release of acrosome enzymes that facilitate sperm penetration of the egg investments. Though AR has been investigated for decades, the initial steps of AR in vivo, however, remain largely unknown. A well elucidated model holds the view that AR occurs on the surface of the zona pellucida (ZP), which is triggered by binding of sperm with one of the ZP glycosylated protein, ZP3. However, this model fails to explain the large number of 'falsely' acrosome-reacted sperms found within the cumulus layer in many species examined. With the emerging evidence of cross-talk between sperm and cumulus cells, the potential significance of AR in the cumulus oophorus, the outer layer of the egg, has been gradually revealed. Here we review the acrosome status within the cumulus layer, the cross-talk between sperm and cumulus cells with the involvement of a novel sperm-released factor, NYD-SP8, and re-evaluate the importance and physiological significance of the AR in the cumulus in fertilization.
受精是一个涉及多个步骤的过程，最终导致一个精子和卵子融合形成受精卵。其中一个步骤是顶体反应（AR），这是一个胞吐过程，在此过程中，顶体膜与精子膜内融合，导致顶体酶释放，促进精子穿透卵子的保护层。尽管 AR 已经研究了几十年，但体内 AR 的初始步骤在很大程度上仍然未知。一个得到充分阐明的模型认为，AR 发生在透明带（ZP）的表面，这是由精子与 ZP 糖蛋白之一 ZP3 的结合触发的。然而，这个模型无法解释在许多检查过的物种中在卵丘层中发现的大量“错误”发生顶体反应的精子。随着精子和卵丘细胞之间的串扰的出现证据，顶体反应在卵丘卵母细胞（卵子的外层）中的潜在意义逐渐显现。在这里，我们回顾了卵丘层中的顶体状态、精子和卵丘细胞之间的串扰以及新型精子释放因子 NYD-SP8 的参与，并重新评估了顶体反应在受精过程中在卵丘中的重要性和生理意义。
