MicroRNA Regulation of Ovarian Function

描述（由申请人提供）：避孕和不孕是育龄妇女面临的两个主要生活质量问题。可受精卵母细胞的排卵和功能性黄体的形成是生殖成功的绝对要求，并由黄体生成素（LH）的中期激增诱导。LH活动中断是不孕症的主要原因，也是许多避孕方法的目标。大量的研究已经表征了LH作用下游的信号级联和转录反应;并且我们对LH及其受体如何能够调节诸如排卵、减数分裂恢复和黄体化等复杂生理过程的理解取得了巨大进展。然而，重要的问题仍然没有解决或未探索，包括基因表达的转录后调控在介导LH作用中的作用。我们最近对Dicer 1缺陷小鼠的研究表明，转录后和特异性microRNA介导的基因调控在排卵中起关键作用。我们还将miR-21鉴定为排卵期卵泡颗粒细胞内LH诱导的microRNA（miRNA），并证明其通过促进整体翻译抑制细胞凋亡并增强颗粒细胞肥大。此外，我们目前的体内研究表明，miR-21的丢失会降低排卵率。因此，该提议的中心假设是miR-21在LH诱导的卵巢功能中起关键作用。为了验证这一中心假设，在Specific Aim 1中，我们确定了miR-21在排卵期卵泡颗粒细胞中的功能及其在排卵、黄体化和卵母细胞能力中的作用。在特定目标2中，我们确定了miR-21在排卵期颗粒细胞内调节的靶转录物和分子途径，而在特定目标3中，我们确定了LH诱导的转录因子调节miR-21基因表达。本资助申请中提出的研究将定义由miR-21介导的转录后基因调节调节所调节的基因子集，并将在功能上将这种miRNA与对卵巢功能至关重要的生理和发育事件联系起来。这项研究的长期益处将增强我们对卵巢的了解，最终影响不孕症治疗策略和女性新避孕方法的发展。 公共卫生相关性：由于卵巢功能障碍如多囊卵巢综合征、短黄体期缺陷和卵母细胞质量受损导致的不孕症是由排卵期卵泡内发生的细胞相互作用破坏和异常引起的。确定调节卵巢功能的因素及其作用机制将为治疗干预提供靶点。这项研究的长期益处将增强我们对卵巢的了解，最终影响改善女性生殖健康的治疗策略的发展。

DESCRIPTION (provided by applicant): Contraception and infertility are two major quality of life issues facing women of reproductive age. Ovulation of a fertilizable oocyte and formation of a functional corpus luteum are absolute requirements for reproductive success and are induced by the mid-cycle surge of luteinizing hormone (LH). Disrupted LH actions are a leading cause of infertility and a target of many contraceptive methods. Numerous studies have characterized the signaling cascades and transcriptional responses downstream of LH action; and dramatic progress in our understanding of how LH and its receptor are able to regulate such complicated physiological processes such as ovulation, resumption of meiosis and luteinization have resulted. However, significant questions still remain unsolved or unexplored, including the role post-transcriptional regulation of gene expression plays in mediating LH action. Our recent studies with Dicer1 deficient mice have implicated post-transcriptional and specifically microRNA mediated gene regulation as playing a key role in ovulation. We have also identified miR-21 as an LH- induced microRNA (miRNA) within granulosa cells of the periovulatory follicle, and demonstrated that it suppresses apoptosis and enhances granulosa cell hypertrophy by promoting global translation. Furthermore, our current in vivo studies demonstrate that loss of miR-21 decreases ovulation rate. Therefore, the central hypothesis of this proposal is that miR-21 plays critical roles in the LH-induced ovarian function. To test this central hypothesis, in Specific Aim1, we determine the function of miR-21 within periovulatory follicular granulosa cells and its role in ovulation, luteinization and oocyte competence. In Specific Aim 2, we identify the target transcripts and molecular pathways miR-21 regulates within periovulatory granulosa cells, while in Specific Aim 3 we determine which LH-induced transcription factors modulate miR-21 gene expression. The studies proposed in this grant application will define a subset of genes regulated by miR-21 mediated post-transcriptional gene regulation and will functionally link this miRNA with physiologic and developmental events critical to ovarian function. The long-term benefits of this research will enhance our understanding of the ovary, ultimately impacting the development of treatment strategies for infertility and new contraceptive methods for women. PUBLIC HEALTH RELEVANCE: Infertility due to ovarian dysfunction such as polycystic ovarian syndrome, short luteal phase defects and compromised oocyte quality result from disrupted and abnormal cellular interactions occurring within the periovulatory follicle. Identifying the factors and their mechanisms of action that regulate ovarian function will provide targets for therapeutic intervention. The long-term benefits of this research will enhance our understanding of the ovary, ultimately impacting the development of treatment strategies that will improve the reproductive health of women.