Signaling Mechanisms of Polyspermy Block

项目概要/摘要： 施肥是自然界中最基本的过程之一，但我们在这方面存在着严重的差距。 了解这个重要的过程。成功的最早和最普遍的障碍之一 生殖是一个卵子被一个以上的精子受精，或多精受精。这个常见的问题， 所有有性繁殖物种的卵都面临着这种问题，它会导致严重的染色体缺陷， 胚胎死亡率该项目将研究确保每个卵子都能存活的分子机制。 只有一个精子受精，因此允许正常的胚胎发育。在许多卵中 在生物体中，受精引起长时间的膜去极化，这是一种快速阻断， 多精受精快速的多精受精阻断需要一个或多个离子通道的活性，但分子水平上， 任何所需信道的标识都是未知的。在许多物种中，包括青蛙，氯离子通道 调解这个过程。巧合的是，受精诱导的Ca 2+增加也发生在禁食之前。 多精生殖阻滞这两个事件之间可能存在联系是最近发现的Ca 2 +- 由TMEM 16 a基因编码的激活的Cl-通道。在具体目标一中，我将确定 受精时去极化所需的Ca ~（2+）。具体目标2中概述的实验将揭示 TMEM 16 a通道在快速多精受精阻滞中的作用。沿着受精诱发的 在Ca 2+中，受精也伴随着磷脂酰肌醇4，5-二磷酸的两倍增加 （PIP2）。这种升高的PIP 2在受精后最初几分钟可能发挥的作用尚不清楚。 因为PIP 2是一种已知的结构多样的离子通道的调节剂，并且因为受精- 诱发的PIP 2升高发生在快速多精受精阻滞的时间范围内，我假设PIP 2 调节受精诱发的去极化。我将在具体目标三中检验这一假设， 确定PIP 2耗尽是否影响多精受精阻断。这些实验的结果将有助于 我们对受精生物学的理解，并将为未来的发展提供基础， 生殖医学

Project Summary/Abstract: Fertilization is one of the most fundamental processes in nature, yet critical gaps exist in our understanding of this essential process. One of the earliest and most prevalent barriers to successful reproduction is the fertilization of an egg by more than one sperm, or polyspermy. This common problem, faced by the eggs of all sexually reproducing species, causes severe chromosomal defects and leads to embryonic mortality. This project will investigate the molecular mechanisms that ensure that each egg is fertilized by only one sperm, thus allowing for normal embryonic development. In the eggs of many organisms, fertilization evokes a prolonged membrane depolarization, which acts as a fast block to polyspermy. The fast polyspermy block requires the activity of one of more ion channel, but the molecular identity of any required channel is not known. In many species, including frogs, Cl- channels likely mediates this process. Coincidentally, a fertilization-induced increase in Ca2+ also occurs prior to the fast polyspermy block. A possible connection between these two events is the recently identified Ca2+- activated Cl- channel encoded by the TMEM16a gene. In specific aim one, I will identify the source of Ca2+ required for the depolarization at fertilization. Experiments outlined in specific aim two will uncover the role of the TMEM16a channel in the fast polyspermy block. Along with a fertilization-evoked increase in Ca2+, fertilization is also accompanied by a two-fold increase in phosphatidylinositol 4,5-bisphosphate (PIP2). The role that this elevated PIP2 may play in the first minutes after fertilization is unknown. Because PIP2 is a known regulator of structurally diverse ion channels and because the fertilization- evoked PIP2 elevation occurs within the time frame of the fast polyspermy block, I hypothesize that PIP2 regulates the fertilization-evoked depolarization. I will test this hypothesis in specific aim three and determine if PIP2 depletion affects the polyspermy block. The results of these experiments will contribute to our understanding of the biology of fertilization, and will provide the basis for future advances is reproductive medicine.