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Regulation and Function of the Rhox8 homeobox gene in granulosa cells

颗粒细胞中 Rhox8 同源盒基因的调控和功能

基本信息

批准号：
7938524
负责人：
JAMES Arthur MACLEAN
金额：
$ 36.38万
依托单位：
SOUTHERN ILLINOIS UNIVERSITY CARBONDALE
依托单位国家：
美国
项目类别：
财政年份：
2010
资助国家：
美国
起止时间：
2010-09-01 至 2013-08-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/7938524
关键词：
5&apos Flanking Region Androgens Animals Apoptosis Binding Sites Biological Process Boxing Cell Differentiation process Cell Proliferation Cell model Cell physiology Complex Defect Development Developmental Process Elements Epididymis Estrogens Event Exhibits Female Fertility Gene Cluster Gene Expression Gene Targeting Genes Germ Cells Goals Gonadal structure Gonadotropins Growing Follicle Homeobox Homeobox Genes Homeodomain Proteins Investigation Knock-out Knowledge Learning Luteal Cells Luteinization Luteinizing Hormone Mediating Mediator of activation protein Mus Mutation Oocytes Ovary Ovulation Pattern Physiology Placenta Process Production Progesterone Progesterone Receptors Receptor Activation Regulation Reproduction Reproductive Process Research Response Elements Rodent Role Signal Pathway Signal Transduction Sperm Count Procedure Sperm Motility Testing Testis Time Tissues Translating X Chromosome cell motility cis acting element corpus luteum folliculogenesis granulosa cell hormone regulation hormone response element male member overexpression postnatal promoter public health relevance receptor binding reproductive reproductive development selective expression sperm cell steroid hormone transcription factor

项目摘要

DESCRIPTION (provided by applicant): Ovulation is a complex and intriguing biological process that is essential for mammalian reproduction. The actions of granulosa cells in the ovary are central to successful ovulation. Initially the follicle consists of a single layer of granulosa cells surrounding each primordial oocyte. Upon stimulation by gonadotropins, granulosa cells rapidly divide and the follicle grows until proliferation is terminated by a surge in luteinizing hormone (LH) which initiates a developmental switch to luteal cells and initiates the signaling cascade that ultimately leads to ovulation. An essential mediator of this process is the steroid hormone progesterone. Knockout studies have identified several progesterone-regulated genes that contribute are necessary for folliculogenesis and ovulation. However, virtually none of these genes are transcribed due to direct progesterone-receptor interaction with their promoters. The Rhox homeodomain protein family has several members that are excellent candidates to regulate events in granulosa cells. While expression of the Rhox genes is restricted to reproductive tissues, ovary, testis, epididymis, and placenta, very few have been examined for function. We have recently discovered that Rhox5-null male mice exhibit lower epididymal sperm numbers, have sperm possessing motility defects, and are subfertile. However, Rhox5- null female mice have no apparent complications in ovulation. Like Rhox5, Rhox8 is highly expressed in a developmentally regulated manner in granulosa cells in a similar "window" of expression. Thus, RHOX8's continued production in Rhox5-null animals may explain why they do not exhibit more severe constraints on their fertility. Furthermore, Rhox8 is unique among the Rhox genes in that it remains expressed through the periovulatory window, suggesting it may be uniquely situated to regulate luteal cell differentiation and the final steps of ovulation. In this application, I propose to determine the regulation and function of Rhox8 in granulosa cells. I propose to accomplish this task by verifying the importance of a putative progesterone response element within Rhox8's promoter as well as investigating the other cis-acting factors that contribute to Rhox8's unique window of expression during folliculogenesis. The timing of Rhox8 induction in the follicle suggests that it may regulate granulosa cell proliferation, survival, and differentiation (functions attribute to progesterone signaling in general). Thus, we will begin to characterize RHOX8's role in these processes using cultured granulosa cells. The elucidation of Rhox8's function in granulosa cells is important because it will provide an important "building block" towards our long-term goal of learning the independent and collaborative functions of all the Rhox genes in the gonads. PUBLIC HEALTH RELEVANCE: Mammalian reproduction requires successful ovulation. While knockout studies have provided definitive proof that progesterone signaling is required for ovulation, the critical downstream effectors of progesterone signaling which have been identified are not directly regulated by progesterone. Currently, there is a gap in our fundamental knowledge concerning transcription factors which translate the progesterone receptor activation signal to the expression of target genes that modulate ovulation. Preliminary studies suggest that Rhox8 is regulated by the coordinated efforts of progesterone receptor and homeobox factors. We believe characterization of the involvement of these cis-acting factors on the Rhox8 promoter and the consequences of Rhox8 disruption in granulosa cells will begin to eliminate some of the "black box" within the progesterone signaling pathway.

描述(申请人提供)：排卵是一个复杂和有趣的生物过程，对哺乳动物的繁殖是必不可少的。卵巢中颗粒细胞的活动是成功排卵的中心。最初，卵泡由包裹着每个原始卵母细胞的单层颗粒细胞组成。在促性腺激素的刺激下，颗粒细胞迅速分裂，卵泡生长，直到黄体激素(LH)激增终止增殖，黄体激素启动发育转换到黄体细胞，并启动信号级联，最终导致排卵。这个过程的一个重要中介是类固醇荷尔蒙黄体酮。基因敲除研究已经确定了几个黄体酮调节基因，它们对卵泡发生和排卵是必要的。然而，由于孕激素受体与其启动子的直接相互作用，这些基因实际上没有一个被转录。Rhox同源结构域蛋白家族有几个成员，它们是调节颗粒细胞事件的极佳候选者。虽然ROX基因的表达仅限于生殖组织、卵巢、睾丸、附睾和胎盘，但很少有人对其功能进行检测。我们最近发现，Rhox5基因缺失的雄性小鼠表现出较低的附睾精子数量，具有精子活力缺陷，并具有低生育能力。然而，Rhox5基因缺失的雌性小鼠在排卵过程中没有明显的并发症。像Rhox5一样，Rhox8在颗粒细胞中以发育调节的方式在类似的表达窗口中高度表达。因此，Rhox8的S在Rhox5缺失动物中的持续生产可能解释了为什么它们没有表现出更严格的生育限制。此外，Rhox8在Rhox基因中是独一无二的，因为它通过排卵周窗口保持表达，这表明它可能是调节黄体细胞分化和排卵最后步骤的独特位置。在这个应用中，我建议确定Rhox8在颗粒细胞中的调节和功能。我建议通过验证Rhox8‘S启动子中可能的孕酮反应元件的重要性以及研究导致Rhox8’S在卵泡发生过程中唯一表达窗口的其他顺式作用因素来完成这一任务。Rhox8在卵泡中的诱导时机表明，它可能调节颗粒细胞的增殖、存活和分化(功能一般归因于孕酮信号)。因此，我们将开始利用培养的颗粒细胞来表征RHOX8的S在这些过程中的作用。阐明Rhox8的S在颗粒细胞中的功能是重要的，因为它将为我们了解性腺中所有Rhox基因的独立和协同功能的长期目标提供重要的“构建块”。公共卫生相关性：哺乳动物的繁殖需要成功排卵。虽然基因敲除研究已经提供了确凿的证据表明孕酮信号是排卵所必需的，但已确定的孕酮信号的关键下游效应因子并不直接受孕酮调节。目前，关于将孕激素受体激活信号转化为调节排卵的靶基因表达的转录因子，我们的基础知识存在差距。初步研究表明，Rhox8受孕激素受体和同源异型盒因子的协同作用调节。我们相信，表征这些顺式作用因子对Rhox8启动子的参与以及Rhox8干扰颗粒细胞的后果将开始消除孕激素信号通路中的一些“黑匣子”。