Deubiquitinating Enzymes as Targets for Male Contraception

 描述（由申请人提供）：本项目的中心目标是鉴定和表征泛素特异性肽酶51（USP 51）的小分子抑制剂，这是一种精子专用的去泛素化（DUB）酶，作为开发可逆的非激素男性避孕药的一种手段。泛素系统是确保哺乳动物细胞内蛋白质周转的基础。泛素活化酶、泛素缀合酶和泛素蛋白连接酶催化泛素分子与蛋白质的连接，这是将它们靶向蛋白酶体进行降解的过程。DUB催化泛素的去除以促进其再循环。我们已经确定USP 51特异性地表达于晚期伸长精子细胞和附睾精子中。使用Vivo-Morpholinos的小鼠中的USP 51消耗由于精子活力的完全阻断而导致雄性不育。 我们的总体假设是达特USP 51是一个可行的避孕靶点，自然界中存在的或在实验室中修饰的小分子将有效且可逆地抑制附睾精子中的USP 51功能。我们将追求以下具体目标来解决这一假设：1）将USP 51作为避孕药开发的有效战略。2)在计算机和体外筛选小分子文库以鉴定命中化合物。3)进行靶向药物化学优化，并评估精子、睾丸和动物暴露于候选药物的有效性和可逆性。这些研究将推进我们对精子发生和精子功能的基本理解，并为开发可逆地抑制关键精子酶的新避孕药提供潜力。

 DESCRIPTION (provided by applicant): The central goal of this project is to identify and characterize small molecule inhibitors of Ubiquitin specific peptidase 51 (USP51), a deubiquitinating (DUB) enzyme exclusive to sperm, as a means to develop a reversible, non-hormonal male contraceptive. The ubiquitin system is fundamental to ensure protein turnover within mammalian cells. Ubiquitin-activating enzymes, ubiquitin-conjugating enzymes, and ubiquitin protein ligases catalyze the attachment of ubiquitin molecules to proteins, a process that targets them to the proteasome for degradation. DUBs catalyze the removal of ubiquitin to facilitate their recycling. We have identified USP51 to be specifically expressed in late elongating spermatids and epididymal sperm. USP51 depletion in mice using Vivo-Morpholinos results in male infertility due to a complete block of sperm motility. Our overall hypothesis is tat USP51 is a viable contraceptive target and that small molecules existing in nature or modified in the laboratory will effectively and reversibly inhibit USP51 function in epididymal sperm. We will pursue the following Specific Aims to address this hypothesis: 1) Validate the targeting of USP51 as an effective strategy for contraceptive development. 2) Screen small molecule libraries in silico and in vitro to identify hit compounds. 3) Perform hit-to-lead medicinal chemistry optimization and assess the exposure of sperm, testes and animals to candidates for efficacy and reversibility. These studies will advance our basic understanding of spermatogenesis and sperm function, as well as provide the potential for developing new contraceptive agents that reversibly inhibit a critical sperm enzyme.