Signaling Mechanisms of Polyspermy Block

项目摘要/摘要： 受精是自然界最基本的过程之一，但在我们的 了解这一基本过程。最早也是最普遍的成功障碍之一 生殖是由一个以上的精子或多精受精使一个卵子受精。这个常见的问题， 面对所有有性繁殖物种的卵，会导致严重的染色体缺陷，并导致 胚胎死亡率。该项目将研究确保每个卵子都是 只由一个精子受精，从而允许正常的胚胎发育。在许多人的卵子里 对于生物体来说，受精会引起长时间的膜去极化，这就像是快速阻止了 多精受精。快速的多精体阻断需要一个或多个离子通道的活性，但分子 任何所需频道的身份都未知。在包括青蛙在内的许多物种中，氯离子通道可能 调解这一过程。巧合的是，受精诱导的钙离子增加也发生在禁食之前 多精受精块。这两个事件之间的一个可能联系是最近发现的钙离子- TMEM16A基因编码的激活的氯离子通道。在具体的目标一中，我将确定 受精时去极化所需的钙离子。在具体目标二中概述的实验将揭示 TMEM16A通道在快速多精受精阻断中的作用伴随着受精引起的增加 在钙离子中，受精还伴随着磷脂酰肌醇4，5-二磷酸的两倍增加 (PIP2)。这种升高的PIP2在受精后的第一分钟可能起到的作用尚不清楚。 因为PIP2是已知的结构多样化的离子通道的调节器，而且因为受精- 诱发的PIP2升高发生在快速多精子阻滞的时间范围内，我假设PIP2 调节受精引起的去极化。我将在三个具体目标中测试这个假设 确定PIP2耗尽是否会影响多精母细胞块。这些实验的结果将有助于 对我们对受精生物学的理解，并将为未来的进展提供基础 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.