Importance of mammalian sperm metalloendoprotease activity during the acrosome reaction to subsequent sperm-egg fusion: inhibitor studies with human sperm and zona-free hamster eggs.
Importance of mammalian sperm metalloendoprotease activity during the acrosome reaction to subsequent sperm-egg fusion: inhibitor studies with human sperm and zona-free hamster eggs.
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哺乳动物精子金属内蛋白酶活性在顶体反应对随后精卵融合过程中的重要性：对人类精子和无透明带仓鼠卵的抑制剂研究。
DOI：
10.1002/mrd.1080310206
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发表时间：
1992
影响因子：
2.5
通讯作者：
Meizel,S
中科院分区：
文献类型：
--
作者：
Diaz-Perez,E;Meizel,S
我们之前已经证明，每种金属内切蛋白酶（MEP）抑制剂phosphoramidon，二亚乙基三胺五乙酸和苄氧羰基-L-苯丙氨酸，当仅在人类精子顶体反应（AR）期间存在时，不会抑制AR或精子活力，但会减少穿透无精子仓鼠卵的精子数量。本研究旨在研究这种渗透抑制是否是由于对精子与卵质膜结合的影响和/或对实际膜融合事件的影响。在这些研究中，我们使用离子霉素启动AR，并在同一实验中测定了无Ca2+培养基中的结合和含Ca2+培养基中的融合。卵细胞中加入荧光染料Hoechst 33342，精子头部出现荧光表明融合已经发生。三种MEP抑制剂仅轻微降低结合，但抑制实际融合步骤50 - 60%（用校正由于结合抑制引起的任何融合抑制的方程测定）。MEP抑制剂只存在于配子相互作用过程中，对融合几乎没有影响。我们还发现，在离子霉素引发的AR过程中释放了磷酰胺可降解的MEP活性。将含有MEP活性的AR上清液与先前经顶体反应的phosphoramidon处理的精子孵育，导致phosphoramidon对精卵融合的抑制作用大幅逆转。这些结果支持以下假设：在AR期间释放的顶体磷酰胺可降解MEP在该事件期间直接或间接地起作用，以增加随后精卵融合所需的精子质膜区域的融合性。
We have previously shown that each of the metalloendoprotease (MEP) inhibitors phosphoramidon, diethylenetriaminepentaacetic acid, and carbobenzoxy‐L‐phenlalanine, when present only during the human sperm acrosome reaction (AR), will not inhibit the AR or sperm motility but will decrease the number of sperm that penetrate zona‐free hamster eggs. The present study was designed to investigate whether this inhibition of penetration is due to an effect on sperm binding to the egg plasma membrane and/or to an effect on the actual membrane fusion event. In these studies we used ionomycin to initiate the AR and assayed binding in a Ca2+‐free medium and fusion in Ca2+‐containing medium in the same experiment. Eggs were loaded with the fluorescent dye Hoechst 33342, and the appearance of fluorescence in a sperm head indicated that fusion had occurred. The three MEP inhibitors reduced binding only slightly but inhibited the actual fusion step by 50–60% (determined with an equation that corrected for any inhibition of fusion due to inhibition of binding). MEP inhibitors present only during gamete interactions had little or no effect on fusion. We also found that phosphoramidon‐inhibitable MEP activity was released during the ionomycin‐initiated AR. Incubation of AR supernatant containing MEP activity with previously acrosome‐reacted, phosphoramidon‐treated sperm resulted in a large reversal of the phosphoramidon‐inhibitory effect on sperm‐egg fusion. These results support the hypothesis that the acrosomal phosphoramidon‐inhibitable MEP released during the AR acts directly or indirectly during that event to increase the fusibility of the sperm plasma membrane region required for subsequent sperm‐egg fusion.