WNT and gonadotropin mediated regulation of ovarian steroidogenesis

描述(由申请人提供)：WNT信号分子家族已被确定为成年女性正常卵巢功能的潜在关键调节因子。众所周知，WNT蛋白是卵巢早期发育所必需的，缺乏WNT4的小鼠有性别反转的卵巢，表达与睾丸发育相关的基因，出生时卵母细胞数量减少。此外，带有颗粒细胞特异性等位基因编码活性连环蛋白的小鼠的连环蛋白信号失控会导致不育症和迟发性颗粒细胞肿瘤的发生。WNT和Frizzleed家族的几个成员在成年啮齿动物卵巢中的表达和激素调节已被报道，WNT信号通路的下游调节因子？-catenin已被证明在卵巢类固醇合成中发挥作用。此外，颗粒细胞中β-连环蛋白的减少影响了FSH对芳香酶mRNA的刺激以及由此产生的雌二醇的产生。尽管有新的证据表明WNT信号通路在调节卵巢发育和类固醇产生中的重要性，但对WNT在成年卵巢中的调节知之甚少。识别其他促进卵巢类固醇产生的因素和机制，如WNT，将有助于深入了解这些信号可能如何影响健康和疾病中的雌激素水平。我们的长期目标是描述成年卵巢中WNT信号的调节机制。这项应用的直接目标是确定WNT信号通路的颗粒细胞特异性靶点，并描述这些靶点是如何受到激素调节的。为了实现这一应用的总体目标，将追求以下具体目标：1.确定FSH和WNT共同调节芳香酶基因表达的机制，芳香酶基因表达是最终诱导卵巢雌二醇产生的关键因素。2.利用基因芯片技术研究WNT和FSH共同调控的颗粒细胞基因网络，绘制大鼠颗粒细胞原代培养的基因表达谱图。这项研究将提供新的靶点和策略，以扩大我们对卵泡发生的激素调节的知识，并可能改进对女性因素不孕症和卵巢病理的治疗。 与公共健康相关：在人类中，局部和循环中的雌激素水平影响着许多生理和病理过程，包括生育和性行为、骨骼重塑和各种内分泌癌的发展。WNT包括一组分泌的糖蛋白家族，它们是卵巢早期发育和类固醇合成所必需的关键细胞外信号蛋白；WNT信号下游辅助激活因子β-catenin的异常调节已被证明在包括颗粒细胞在内的许多组织中导致癌症。了解Wnt/？-catenin在卵巢中的作用，以及这一途径如何与其他细胞外信号汇聚，将有助于更好地了解这些信号如何影响健康和疾病中的卵泡成熟和雌激素水平。

DESCRIPTION (provided by applicant): The WNT family of signaling molecules has been identified as potential key regulators of normal ovarian function in the adult female. It is known that WNT proteins are required for early ovarian development and that mice lacking Wnt4 have sex-reversed ovaries, express genes associated with testes development and exhibit a reduced number of oocytes at birth. Additionally, misregulated ¿-catenin signaling in mice with granulosa cell-specific alleles encoding constitutively active ¿-catenin results in subfertility and the development of late onset granulosa cell tumors. Expression and hormonal regulation of several members of the WNT and Frizzled families have been reported in the adult rodent ovary and the downstream regulator of the WNT signaling pathway, ¿-catenin, has been shown to play a role in ovarian steroidogenesis. Moreover, reduction of ¿-catenin in granulosa cells compromises FSH stimulation of aromatase mRNA and resultant estradiol production. Despite emerging evidence as to the importance of the WNT signaling pathway in regulating ovarian development and steroid production, very little is known about the regulation of WNTs in the adult ovary. Identification of additional factors and mechanisms, such as WNT, that contribute to ovarian steroid production will provide insight to how these signals may impact estrogen levels in health and disease. Our long-term goal is to describe the mechanisms regulating WNT signaling in the adult ovary. The immediate goal of this application is to determine granulosa cell specific targets of the WNT signaling pathway and delineate how these targets are hormonally regulated. To accomplish the overall objective of this application the following specific aims will be pursued: 1. Determine the mechanisms by which FSH and WNT work together to regulate aromatase gene expression which is ultimately responsible for induction of ovarian estradiol production. 2. Investigate the common network of genes regulated by WNT and FSH in granulosa cells using microarray analysis to map the gene expression profiles in primary cultures of rat granulosa cells. This research will provide new targets and strategies to expand our knowledge about hormonal regulation of folliculogenesis and could improve treatments for female factor infertility and ovarian pathologies. PUBLIC HEALTH RELEVANCE: In humans, local and circulating estrogen levels influence numerous physiological and pathological processes including fertility and sexual behavior, bone remodeling and the development of various endocrine cancers. WNTs comprise a family of secreted glycoproteins that are key extracellular signaling proteins necessary for early ovarian development and steroidogenesis; aberrant regulation of the downstream co-activator of WNT signaling, ¿-catenin has been shown to cause cancer in a number of tissues including granulosa cells. Understanding the role of WNT/ ¿-catenin in the ovary and how this pathway converges with other extracellular signals will allow greater perspective on how these signals impact follicular maturation and estrogen levels in health and disease.