EXOCYTOTIC SIGNALING THROUGH SPERM RECEPTORS FOR EGGS

通过精子受体向卵子发出胞外信号

• 批准号: 6499140
• 负责人: DAVID Joel MILLER
• 金额: $ 13.36万
• 依托单位: UNIVERSITY OF ILLINOIS AT URBANA-CHAMPAIGN
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-02-01 至 2005-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6499140
• 关键词: CD38 molecule; G protein; Xenopus oocyte; acrosome; benzoates; biological signal transduction; chimeric proteins; cytoplasm; egg /ovum; enzyme activity; enzyme inhibitors; exocytosis; fertility immunology; fertilization; galactosyltransferases; gene mutation; genetically modified animals; laboratory mouse; neutralizing antibody; protein tyrosine kinase

Our long-range objective is to develop a clearer fundamental understanding of the molecular basis of fertilization so that the process can be controlled to either promote fertilization or block it. Much progress has been made to identify ZP3, the protein in the mammalian egg coat that binds sperm and stimulates the acrosome reaction, the release of the acrosomal vesicle that must occur for sperm to penetrate the egg coat. Despite this progress, the identity of the ZP3 receptor on sperm has been elusive. One strong candidate is beta1,4-galactosyltransferase, an enzyme first discovered in the Golgi apparatus of somatic cells but later found on the surface of sperm. Beta1,4-Galactosyltransferase binds ZP3 but not other egg coat proteins. In addition to its role in gamete adhesion, beta1,4- galactosyltransferase acts to trigger the acrosome reaction in sperm. The acrosome reaction can be stimulated with antibodies to beta1,4-galactosyltransferase that act as mimics of ZP3 to bind and crosslink beta1,4-galactosyltransferase. There is evidence that binding beta1,4-galactosyltransferase stimulates at least some of the same signaling systems inside sperm that ZP3 stimulates, leading to the proposal that beta1,4- galactosyltransferase may be the major ZP3 receptor signaling the acrosome reaction. Mice with a targeted deletion of the beta1,4-galactosyltransferase gene, although fertile, produce sperm with severely compromised ability to acrosome react and penetrate the egg coat. In this proposal, the signaling systems that are activated by beta1,4-galactosyltransferase will be studied. The goals are to determine if binding beta1,4-galactosyltransferase specifically can completely reproduce all of the identified signaling systems activated by ZP3 binding, to study beta1,4-galactosyltransferase mutants to identify structural features necessary for signaling, and to identify proteins that interact with the portion of beta1,4- galactosyltransferase found in the cytosol. These studies will clarify the role of a sperm receptor for the egg coat in the acrosome reaction, a necessary step in the process of fertilization.

我们的长期目标是对受精的分子基础有更清晰的基本了解，以便可以控制该过程以促进受精或阻止受精。 ZP3 是哺乳动物卵膜中的一种蛋白质，它与精子结合并刺激顶体反应，即精子穿透卵膜所必须释放的顶体囊泡的释放，在鉴定 ZP3 方面已经取得了很大进展。 尽管取得了这些进展，但精子上 ZP3 受体的身份仍然难以捉摸。 一个强有力的候选者是β1,4-半乳糖基转移酶，这种酶首先在体细胞的高尔基体中发现，但后来在精子表面发现。 Beta1,4-半乳糖基转移酶结合 ZP3，但不结合其他蛋壳蛋白。 除了在配子粘附中发挥作用外，β1,4-半乳糖基转移酶还可触发精子中的顶体反应。 顶体反应可以用β1,4-半乳糖基转移酶抗体刺激，该抗体作为ZP3的模拟物来结合和交联β1,4-半乳糖基转移酶。 有证据表明，结合β1,4-半乳糖基转移酶会刺激精子内至少一些与ZP3刺激相同的信号系统，从而提出β1,4-半乳糖基转移酶可能是顶体反应信号传导的主要ZP3受体。 β1,4-半乳糖基转移酶基因被靶向删除的小鼠虽然具有生育能力，但产生的精子的顶体反应和穿透卵膜的能力严重受损。 在本提案中，将研究由 β1,4-半乳糖基转移酶激活的信号系统。 目标是确定特异性结合β1,4-半乳糖基转移酶是否可以完全重现所有已识别的由ZP3结合激活的信号系统，研究β1,4-半乳糖基转移酶突变体以鉴定信号传导所需的结构特征，并鉴定与胞质中发现的β1,4-半乳糖基转移酶部分相互作用的蛋白质。 这些研究将阐明卵衣精子受体在顶体反应中的作用，顶体反应是受精过程中的必要步骤。