Male contraception/CatSper1,2 sperm-specific ion channel

描述(申请人提供)：精子和卵子的融合导致父亲和母亲的遗传信息结合在一起，创造出一个新的个体。对于人类，就像所有哺乳动物一样，精子必须到达卵子，穿透卵子的保护层，与卵细胞膜融合，并传递其遗传物质。精子中的离子通道介导了其中的许多步骤，但这些离子通道中的大多数也存在于其他组织中，包括大脑和心脏。我们已经确定了一类离子通道，称为CatSpers(精子的阳离子通道)，它存在于成熟的精子中，但不存在于身体的任何其他组织，包括发育中的器官。CatSpers是六种跨膜离子通道蛋白，主要定位于成熟精子的尾部(任等人，2001年)。CatSper1是第一个被发现的离子通道，它触发钙离子流入精子尾巴的主要部分。精子运动需要钙，而缺乏功能CatSper1基因的转基因小鼠的精子运动能力显著降低。CatSper1基因零突变纯合的雄性小鼠是不育的(100%)，但其他方面是完全正常的。另一种与精子相关的蛋白CatSper2也定位于它的尾巴。由于这些离子通道只存在于成熟精子中，是生育所必需的，因此应该使用一种特定的试剂来阻断通道功能，以防止受精。提出的实验将使这些新基因在适合大规模筛选小分子阻滞剂的异源细胞系中表达。这将为男性避孕药的筛查提供一种可行的方法。

DESCRIPTION (provided by applicant): The fusion of sperm and egg lead to the combination of the father's and mother's genetic information to create a new individual. In humans, as in all mammals, sperm must reach the egg, penetrate its protective coat, fuse with the oocyte membrane, and deliver its genetic material. Ion channels in the sperm mediate many of these steps, but most of these ion channels are also present in other tissues, including brain and heart. We have identified a class of ion channels, called CatSpers (Cation channel of Sperm) that are in mature sperm but not in any other tissues of the body, including developing organs. CatSpers are six transmembrane-spanning ion channel proteins localized primarily to the tail of mature sperm (Ren et al., 2001). CatSper1, the first of these ion channels to be identified, triggers calcium influx into the principal piece of the sperm tail. Calcium is required for sperm motility, and sperm from mice genetically engineered to lack the functional CatSper1 gene show a significant reduction in motility. Male mice homozygous for null-mutations in the CatSper1 gene are infertile (100%), but otherwise are completely normal. Another related sperm-specific protein, CatSper2, is also localized to its tail. Since these ion channels are only in mature sperm and required for fertility, a specific agent that blocks channel function should prevent fertilization. Experiments are proposed that will enable the expression of these novel genes in heterologous cell lines suitable for large-scale screening for small molecule blockers. This will provide a viable assay for screening for male contraceptive agents.