Inhibin Actions on Reproductive Target Tissues

描述(申请人提供)：这项研究计划的目的是了解导致卵巢颗粒细胞抑制素分泌的生物合成途径。抑制素在体外和体内最公认的作用是抑制垂体促性腺激素产生和分泌FSH。抑制素水平在生殖周期中受到调节，以确保正常的FSH依赖的卵泡招募。关于导致抑制素生物合成的细胞途径知之甚少，然而，正是这次赠款更新的主题是，这些途径负责准确地产生这种关键的卵巢反馈激素，并对正常的生殖功能至关重要。 抑制素A和抑制素B是由卵巢颗粒细胞产生的，然而，这些配体的分泌模式是不同的，这表明对生物合成和释放的潜在控制以前没有被研究过。此外，许多颗粒细胞产物靶向胃窦液或血管膜细胞室的确切机制尚不清楚。我们的初步研究已经确定了大鼠生殖周期中抑制素A和抑制素B的不同分泌模式，描述了发育中卵泡颗粒细胞中抑制素亚单位蛋白的差异区划，并揭示了抑制素异构体的生物合成过程是受调控的。这些初步研究和过去五年的工作结果表明，调节抑制素生物合成和加工的细胞机制对抑制素的作用非常重要，必须进行研究，以便更全面地了解这种配体在女性和男性中的功能。我们假设抑制素的生物活性依赖于翻译后修饰，包括N-连接的糖基化，激素原结构域中包含的蛋白质特异性路由信号，以及将生物失活的前配体转化为成熟的、具有生物活性的抑制素的生物处理酶。在这项提案中有三个相互关联的实验目标，它们将解决中心假设及其原则。这些研究有望为抑制素合成和释放的控制提供洞察力，并有助于更全面地了解正常生育能力以及由于激素作用不当而导致女性生育相关疾病的机制。

DESCRIPTION (provided by applicant): The objective of this research proposal is to understand the biosynthetic pathways leading to inhibin secretion from ovarian granulosa cells. The most recognized action of inhibin is to suppress FSH production and secretion by the pituitary gonadotrope in vitro and in vivo. Inhibin levels are regulated during the reproductive cycle to ensure normal FSH-dependent follicle recruitment. Little is known regarding the cellular pathways leading to inhibin biosynthesis, yet, it is the thesis of this grant renewal that these pathways are responsible for the accurate production of this key ovarian feedback hormone and are vital to normal reproductive function. Inhibin A and inhibin B are produced by the granulosa cell of the ovary, however, the secretion patterns for these ligands are distinct, suggesting an underlying control over biosynthesis and release that has not been previously investigated. In addition, the precise mechanism by which many granulosa cell products are targeted toward the antral fluid or the vascular theca cell compartment is not well understood. Our preliminary studies have identified differential secretion patterns of inhibin A and inhibin B during the rat reproductive cycle, described differential compartmentalization of inhibin subunit protein in granulosa cells of developing follicles, and revealed that the biosynthetic processing of inhibin isoforms is regulated. These preliminary studies and the results of the past five years of work suggest that the cellular machinery that regulates inhibin biosynthesis and processing is important to inhibin action and must be investigated in order to more completely understand the function of this ligand in women and men. We hypothesize that inhibin bioactivity relies on post-translational modification including N-linked glycosylation, protein specific routing signals contained in pro-hormone domains, and bioprocessing enzymes that convert bioinactive pro-ligand into mature, bioactive inhibin. There are three interrelated experimental aims in this proposal that will address the central hypothesis and its tenets. These studies are expected to provide insight into the control of inhibin synthesis and release and contribute to a more complete understanding of normal fertility and the mechanisms that underlie fertilityrelated diseases in women resulting from inappropriate hormone action.