THE MEMBRANE BLOCK TO POLYSPERMY IN MAMMALIAN EGGS

哺乳动物卵子中多精受精的膜阻滞

• 批准号: 6924957
• 负责人: JANICE P EVANS
• 金额: $ 27.24万
• 依托单位: JOHNS HOPKINS UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-04-20 至 2010-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6924957
• 关键词: RNA interference; actin binding protein; annexins; artificial fertilization; biological signal transduction; calcineurin; calcium flux; calmodulin dependent protein kinase; calpain; cell membrane; cytoskeleton; egg /ovum; endocytosis; exocytosis; fertilization; in vitro fertilization; kinase inhibitor; laboratory mouse; membrane proteins; parthenogenesis; polyploidy; protein kinase C; protein structure function; sperm; tetraspanin; vitelline membrane

DESCRIPTION (provided by applicant): Polyspermy, or fertilization of an egg by more than 1 sperm, is believed to be the cause of at least 5% of spontaneous pregnancy loss in humans. To inhibit fertilization by additional sperm, eggs have developed preventative mechanisms known as blocks to polyspermy. The block at the level of the egg extra cellular coat has been well characterized in many different animal species, and the block at the level of the egg plasma membrane is understood in some non-mammalian species. However, virtually nothing is known about the membrane block to polyspermy in mammalian eggs, despite data dating back 50-90 years that provide evidence for its existence. Our recent data demonstrates that sperm-induced Ca2+ signaling and the egg actin cytoskeleton are 2 components involved in this post-fertilization change that transforms the egg membrane from a form that supports fertilization to 1 that prevents it. The broad, long-term goal of this project is elucidating the mechanism of the membrane block to polyspermy, from the fertilization-associated signaling that initiates membrane block establishment to the changes in the egg membrane and cortex that prevent additional fertilization. To make progress toward this goal and to build on our recent published and preliminary data, our studies in this proposal will address the following specific aims. Specific Aim 1 will determine the mechanisms by which sperm and sperm-induced Ca2+ signaling induce the establishment of the membrane block. This aim will identify what sperm component(s) is involved in membrane block establishment and how sperm-induced Ca2+ signaling affects characteristics of the membrane block. Specific Aim 2 will characterize the next step in the pathway following Ca2+ by identifying the Ca2+-dependent effector molecules that are involved in the establishment of the membrane block to polyspermy. Finally, Specific Aim 3 will focus on the later steps of the pathway culminating in the membrane block to polyspermy, examining specific changes in the egg membrane and cortex. This aim will test the hypotheses that cortical granule exocytosis, endocytosis, and post-fertilization changes in cortex composition and membrane order contribute to the down-regulation of egg membrane receptivity to sperm that follows fertilization. These inquiries into sperm-induced signaling, calcium, and post-fertilization membrane and cortical dynamics will provide important insights into the cellular and molecular mechanisms underlying the mammalian membrane block to polyspermy, advancing our knowledge of this fundamental question in reproductive and developmental biology.

描述(申请人提供)：多精受精，即一个以上的精子受精一个卵子，被认为是至少5%的人类自发妊娠损失的原因。为了抑制额外精子的受精，卵子已经开发出了被称为阻止多精受精的预防机制。卵细胞外膜水平的阻塞在许多不同的动物物种中都有很好的特征，而在一些非哺乳动物物种中，卵质膜水平的阻塞是被理解的。然而，尽管50-90年前的数据为多精受精的存在提供了证据，但对哺乳动物卵子中多精受精的膜阻断几乎一无所知。我们最近的数据表明，精子诱导的钙信号和卵子肌动蛋白细胞骨架是受精后卵膜从支持受精的形式转变为阻止受精的1的两个组成部分。这个项目的长期目标是阐明膜阻塞对多精受精的作用机制，从启动膜阻塞建立的受精相关信号到阻止额外受精的卵膜和皮质的变化。为了在实现这一目标方面取得进展，并在我们最近公布的初步数据的基础上，我们在这项提案中的研究将涉及以下具体目标。具体目标1将确定精子和精子诱导的钙信号诱导膜阻断建立的机制。这一目标将确定哪些精子成分(S)参与了膜阻断的建立，以及精子诱导的钙信号如何影响膜阻断的特征。具体目标2将通过鉴定参与建立多精受精的膜阻断的钙依赖效应分子来表征钙离子途径的下一步。最后，特定目标3将重点放在最终到达多精受精的膜阻断的途径的后期步骤，检查卵膜和皮质的特定变化。这一目标将检验这样的假设，即皮质颗粒的胞吐作用、内吞作用以及受精后皮质成分和膜顺序的变化有助于受精后卵膜对精子的接受性下调。这些对精子诱导信号、钙、受精后膜和皮质动力学的研究将为哺乳动物膜阻止多精受精的细胞和分子机制提供重要的见解，促进我们对生殖和发育生物学中这一基本问题的认识。