Elucidation of membrane fusion machinery in fertilization

尽管精子-卵子融合在受精过程中具有重要的生物学意义，但这一步骤背后的分子机制在很大程度上仍不清楚。我们利用基因操作的小鼠来阐明精子-卵子融合的分子机制。在本申请中，我们达到了关于哺乳动物受精的两个方面的研究。我们在精子中发现了一种IZUMO1相互作用蛋白。我们建立了一个ACE3干扰的小鼠系，发现IZUMO1在精子上的定位范围更广，但ACE3的消除并不会导致精子受精能力的丧失。利用Izumo1缺陷的精子，我们发现精子至少有两次通过ZP的能力。显然，一些精子在与ZP接触很久之前就已经经历了顶体反应，但仍然能够穿越ZP并使卵子受精。顶体反应的精子不能与ZP结合并失去受精能力的概念必须重新考虑。

Despite the biological importance of sperm-egg fusion in fertilization, the molecular mechanisms underlying this step remain largely unknown. We focused on elucidating the molecular mechanisms of sperm-egg fusion by using genetically manipulated mice. In this application, we reached to obtain two aspects about mammalian fertilization as follows. We identified an IZUMO1-interacting protein in spermatozoon. We produced an Ace3 disrupted mouse line, and found the localization of IZUMO1 spread in a little wider area on spermatozoa, but the elimination of ACE3 did not result in a loss of sperm fertilizing ability. Utilizing Izumo1-deficient spermatozoa, we found that the spermatozoa had the ability to pass through the ZP at least twice. Apparently, some spermatozoa that had undergone the acrosome reaction long before contact with the ZP remained capable of crossing the ZP and fertilizing eggs. The concept that acrosome-reacted spermatozoa are unable to bind to the ZP and have lost their fertilizing capacity must be reconsidered.