A sperm GPI-anchored protein elicits sperm-cumulus cross-talk leading to the acrosome reaction
2009
Yin, L | Chung, C. M | Huo, R | Liu, H | Zhou, C | Xu, W | Zhu, H | Zhang, J | Shi, Q | Wong, H. Y. C | Chen, J | Lu, Y | Bi, Y | Zhao, C | Du, Y | Ma, M | Cai, Y | Chen, W. Y | Fok, K. L | Tsang, L. L | Li, K | Ni, Y | Chung, Y. W | Zhou, Z | Sha, J | Chan, H. C
The acrosome reaction has long been thought to be induced by the zona pellucida. Here we report the identification and function of a novel human sperm glycosylphosphatidylinositol (GPI)-anchored membrane protein, NYD-SP8. The release of the protein during sperm-egg interaction and its binding to the cumulus, the first layer of egg investment, elicits cross-talk between the gametes and produces calcium dependant release of progesterone, which lead to the acrosome reaction. An in vivo mouse model of NYD-SP8 immunization is also established showing a reduced fertility rate. Thus, contrary to accepted dogma, our study demonstrates for the first time that, prior to reaching the zona pellucida, sperm may release a surface protein that acts on the cumulus cells leading to the acrosome reaction, which may be important for determining the outcome of fertilization.
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