A Novel Function of the Oocyte in Estrogen-Regulated FSH Action

描述(由申请人提供)：在女性中，与年龄相关的卵巢储备减少最不利的一个功能是生育力下降。这种与年龄相关的变化的基础是优势卵泡无法释放可以进行正常胚胎发育的卵子。目前的观点是，36岁以后女性生育力下降的机制与促性腺激素的作用增强有关。这笔赠款代表着在理解FSH作用机制方面的一个令人兴奋的进步。利用大鼠模型，我们最近发现，卵母细胞在增强颗粒细胞FSH作用的雌激素活性中是必不可少的。我们还发现，雌激素和卵母细胞的协同作用发生在FSH受体下游和腺苷环化酶上游。进一步的研究首次证明颗粒细胞中存在G蛋白偶联受体激酶(GRK)/β-arrestin系统。此外，我们还证明，只有在有卵母细胞存在的情况下，雌激素才能选择性地抑制GRK-6的作用，这表明雌激素和卵母细胞通过阻止GRK-6/β-arrestin介导的生物学作用而协同增强FSH的作用，这些生物学作用包括G蛋白信号的脱敏和FSH诱导的丝裂原活化蛋白激酶信号转导的激活。在这份R21拨款提案中，我们将阐明卵母细胞在介导雌激素对颗粒细胞FSH敏感性的作用中所起的强制性作用的分子机制。在目标1中，我们将验证我们的假设，即GRK-6/β-arrestin系统参与雌激素-卵母细胞共同处理增强FSH作用的机制。我们还将提供对卵巢GRK/β-arrestin系统的首次全面分析，该系统与FSH受体活性的调节有关。在目标2中，我们将解剖雌激素作用所需的卵母细胞和颗粒细胞之间的通讯网络，并探索卵母细胞和颗粒细胞如何通讯以促进雌激素刺激FSH的作用。此外，我们将利用蛋白质组学和基因芯片技术，确定在雌激素存在的情况下，在卵母细胞和颗粒细胞之间的通讯网络中发挥作用的因子(S)，以增强FSH的作用。微阵列分析。该项目将GRK/β-arrestin系统引入卵巢生理，为理解雌激素在哺乳动物卵巢中作用的分子和细胞机制提供了一个新的概念框架，并可能在开发治疗卵巢功能障碍的药物方案方面取得突破，特别是在老年妇女中。公共卫生相关性：卵泡刺激素(FSH)是卵巢功能所必需的激素，包括卵泡发育和排卵。我们最近发现，在有卵母细胞存在而不是没有卵母细胞的情况下，雌激素可以增强卵泡细胞中的FSH活性。这项拟议的研究旨在阐明这一发现的分子和细胞机制，这可能导致开发治疗卵巢功能障碍的药物方案，特别是在老年妇女。

DESCRIPTION (provided by applicant): In women, one function most adversely affected by the age-related decrease in ovary reserve is decreased fecundity. The basis for this age-related change is the failure of dominant follicles to release eggs that can undergo normal embryonic development. The current thinking is that increased FSH action is involved in the mechanisms underlying decreased fecundity in women after 36 years of age. This grant represents an exciting advance in understanding the mechanisms of FSH action. Using the rat model, we have recently discovered that the oocyte is essential for estrogen activity in enhancing FSH action in granulosa cells. We have also found that the synergistic action of estrogen and oocytes occurs at a site downstream of the FSH receptor and upstream of adenylate cyclase. Further studies have provided the first evidence for a functional G protein-coupled receptor kinase (GRK)/?-arrestin system present in granulosa cells. Moreover, we demonstrate that GRK-6 is selectively suppressed by estrogen only in the presence of oocytes, suggesting that estrogen and oocytes synergistically enhance FSH action by preventing GRK-6/?-arrestin-mediated biological actions including desensitization of G protein signaling and activation of mitogen-activated protein kinase signal transduction induced by FSH. In this R21 grant proposal, we will elucidate the molecular mechanisms by which the oocyte plays an obligatory role in mediating estrogen action on the FSH sensitivity of granulosa cells. In Aim 1, we will test our hypothesis that the GRK-6/?-arrestin system is involved in the mechanism by which estrogen-oocyte co-treatment enhances FSH action. We will also provide the first comprehensive analysis of the ovarian GRK/?-arrestin system, which has been implicated in the mediation of the FSH receptor activity. In Aim 2, we will dissect the communication network between the oocyte and granulosa cell that is required for estrogen action and explore how oocytes and granulosa cells communicate in order for estrogen to stimulate FSH action. Moreover, we will identify the factor(s) that acts in the communication network between oocytes and granulosa cells to augment FSH action in the presence of estrogen, using proteomics and GeneChip. microarray analyses. The proposed project should provide a novel conceptual framework for understanding the molecular and cellular mechanisms of estrogen action in mammalian ovaries by introducing the GRK/?-arrestin system into the ovarian physiology and may lead a breakthrough in developing pharmacological regimens for treating ovarian dysfunctions, particularly in aging women. PUBLIC HEALTH RELEVANCE: Follicle-stimulating hormone (FSH) is an essential hormone for the ovarian function that includes follicle development and ovulation. We have recently discovered that estrogen enhances FSH action in follicular cells in the presence, but not absence, of oocytes. The proposed studies aim to elucidate the molecular and cellular mechanisms of this finding, which may lead to develop pharmaceutical regimens for treating ovarian dysfunctions, particularly in aging women.