Yamashita Misuzu, Honda Arata, Ogura Atsuo, Kashiwabara Shin-ichi, Fukami Kiyoko, Baba Tadashi
Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba Science City, Ibaraki 305-8572, Japan.
Genes Cells. 2008 Oct;13(10):1001-13. doi: 10.1111/j.1365-2443.2008.01222.x. Epub 2008 Aug 27.
Although the acrosome reaction and subsequent penetration of sperm through the egg zona pellucida (ZP) are essential for mammalian fertilization, the molecular mechanism is still controversial. We have previously identified serine protease Tesp5 identical to Prss21 on the mouse sperm surface as a candidate enzyme involved in sperm penetration through the ZP. Here we show that despite normal fertility of male mice lacking Prss21/Tesp5, the epididymal sperm penetrates the ZP only at a very low rate in vitro, presumably owing to the reduced ability to bind the ZP and undergo the ZP-induced acrosome reaction. The ability of Prss21-null sperm to fuse with the egg in vitro was also impaired severely. Intriguingly, the reduced fertility of Prss21-null epididymal sperm was rescued by exposure of the sperm to the uterine microenvironment and by in vitro treatment of the sperm with uterine fluids. These data suggest the physiological importance of sperm transport through the uterus.
尽管顶体反应以及随后精子穿过卵透明带（ZP）对于哺乳动物受精至关重要，但其分子机制仍存在争议。我们之前已鉴定出小鼠精子表面与Prss21相同的丝氨酸蛋白酶Tesp5是参与精子穿过ZP的一种候选酶。在此我们表明，尽管缺乏Prss21/Tesp5的雄性小鼠生育能力正常，但附睾精子在体外仅以非常低的速率穿过ZP，推测是由于结合ZP和发生ZP诱导的顶体反应的能力降低。Prss21基因缺失的精子在体外与卵子融合的能力也严重受损。有趣的是，将精子暴露于子宫微环境以及用子宫液对精子进行体外处理可挽救Prss21基因缺失的附睾精子生育力降低的情况。这些数据表明精子通过子宫运输的生理重要性。
