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Mechanism for the regulation of sperm flagellar motility by ubiquitin/proteasome system

泛素/蛋白酶体系统调节精子鞭毛运动的机制

基本信息

批准号：
12640660
负责人：
INABA Kazuo
金额：
$ 2.37万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2001
项目状态：
已结题

项目摘要

Ubiquitin/proteasome system is involved in the degradation of short life-time proteins and the regulation of several important intracellular processes. It also plays important roles in the process of fertilization, such as sperm-egg interaction and the regulation of sperm motility. In this research several approach were conducted to reveal the mechanism for the regulation of sperm motility by this system, with salmonid fish and ascidian as experimental materials. First, apart from a dynein light chain which is closely related to sperm proteasome system, I have identified a novel 15 kDa protein of which phosphorylation is regulated by proteasome. The protein is shown to be located at the base of the flagellum. Second, the proteasome system is shown to be upstream regulated by membrane hyperpolarization exerted by a pottasium channel. Third, research was conducted to reveal if ubiquitinated proteins were present in broad range of organisms. It was shown that salmonid fish sperm contain no detectable ubiquitinated protein, however ascidian sperm show high content in ubiquitinated proteins. In ascidian sperm, ubiquitin is localized in the region between sperm nucleus and mitochondrion. These suggest that ubiquitin is involved not in the general aspect of sperm function such as sperm motility but in ascidian-specific process, most likely in mitochndrial discrimination observed at fertilization. Finally several genes for ubiquitin/ proteasome system have been isolated by overall anaysis of genes expressed in Ciona testis. The 12,000 ESTs so far analyzed contain several enzymes for protein ubiquitination and components of 26 S proteins. These cDNAs would surely provide a powerful tools for further research on the function of ubiquitin/ proteasome system in sperm cells.

泛素/蛋白酶体系统参与了短寿命蛋白质的降解和几个重要的细胞内过程的调节。它还在受精过程中发挥重要作用，如精子与卵子的相互作用和精子运动的调节。本研究以鲑鱼和海鞘为实验材料，从多种途径揭示了该系统对精子活力的调节机制。首先，除了与精子蛋白酶体系统密切相关的动力蛋白轻链外，我还鉴定了一种新的15 kDa蛋白，其磷酸化受蛋白酶体调节。该蛋白质位于鞭毛的底部。其次，蛋白酶体系统的上游受钾通道施加的膜超极化调节。第三，研究揭示了泛素化蛋白质是否存在于广泛的生物体中。结果表明，鲑鱼精子中不含有可检测到的泛素化蛋白，而海鞘鱼类精子中泛素化蛋白含量较高。在海鞘精子中，泛素定位于精子核和线粒体之间。这表明泛素不参与精子功能的一般方面，如精子活力，而是参与海鞘的特定过程，很可能是受精时观察到的线粒体识别。最后，通过对Ciona睾丸中表达基因的全面分析，获得了几个与泛素/蛋白酶体系统相关的基因。到目前为止，分析的12,000个EST包含几种蛋白质泛素化的酶和26种S蛋白质的成分。这些基因为进一步研究精子细胞中泛素/蛋白酶体系统的功能提供了有力的工具。