Cyclic Nucleotide-Activated Calcium Channels in Sperm

描述(申请人提供)：本研究的总体目标是在分子水平上了解钙、环核苷酸和离子通道对精子功能的调节。这项建议的重点是我们发现的精子尾离子通道(CatSper1)的作用。来自人和小鼠的CatSper1只在睾丸中表达。精子中的蛋白质显著地定位在主膜上。缺乏CatSper1的小鼠除了雄性完全不育外，没有表现出明显的表型。在CatSper1基因缺失的小鼠中，环状AMP诱导的钙内流到精子中是缺陷的。由于CatSper1在精子尾部有限的蛋白表达，以及在男性生育能力中的限制性敲除表型，CatSper1是安全的非激素男性避孕药的良好靶点。目的1确定CatSper1在男性生育中的生理作用。将对CatSper1缺乏的男性进行详细检查，并确定导致男性不育的原因(S)。目的2将揭示CatSper1在精子发生和精子成熟过程中功能调节的分子机制。将检验四个假设：a.调节CatSper1蛋白的表达；b.调节蛋白质的质膜定位；c.修饰蛋白质；以及d.调节通道核心蛋白复合体的组成。目的3将测试目前的模型，关于环核苷酸门控(CNG)离子通道在精子cAMP诱导的钙内流中的作用。目的4验证CatSper1通道介导“cAMP-钙正反馈环”的假说，cAMP引起钙通过该通道内流，由此产生的钙增加，进而导致cAMP升高。这项研究的结果将使我们了解精子运动的离子机制，并可能为未来开发治疗不育症的药物和男性避孕药物奠定基础。

DESCRIPTION (provided by applicant): The overall goal of this research is to understand the sperm function regulation by calcium, cyclic nucleotides and ion channels at the molecular level. This proposal focuses on the roles of a sperm tail ion channel (CatSper1) we discovered. CatSper1 from human and mice is only expressed in testis. The protein in sperm is strikingly localized in the principal piece membrane. Mice deficient in CatSper1 show no gross phenotypes except that males are completely infertile. The cyclic AMP-induced calcium influx into sperm is deficient in CatSper1-null mice. Because of its restricted protein expression in sperm tail and because of its restricted knockout phenotype in male fertility, CatSper1 represents an excellent target for safe non-hormonal male contraceptives. Aim 1 will determine the physiological roles of CatSper1 in male fertility. CatSper1-deficient males will be examined in detail and the reason(s) for male infertility will be determined. Aim 2 will uncover the molecular mechanism underlying the CatSper1 function regulation during spermatogenesis and sperm maturation. Four hypotheses will be tested: a. the CatSper1 protein expression is regulated; b. the protein's plasma membrane localization is regulated; c. the protein is modified; and d. the composition of the channel core protein complex is modulated. Aim 3 will test the current model concerning the roles of the cyclic nucleotide-gated (CNG) ion channels in the sperm cAMP-induced calcium influx. Aim 4 will test the hypothesis that the CatSper1 channel mediates a "cAMP- calcium positive feedback loop" in that cAMP causes calcium influx through the channel and the resulting calcium increase, in turn, causes cAMP to rise. Results from this study will allow us to understand the ion mechanism underlying sperm motility and may lay the foundation for the future development of drugs for infertility treatment and for male contraceptives.