GPR54 and the GnRH Neuron in the Regulation of Puberty and Reproduction

描述(申请人提供)：促性腺激素释放激素(GnRH)神经元的激活是成功启动青春期的关键。然而，发生这种情况的机制还没有被很好地理解。强有力的证据支持Kispeptin-Gpr54系统作为这一过程的核心贡献者的作用。具有G蛋白偶联受体Gpr54失活突变的人类和小鼠促性腺激素水平较低，无法经历正常的青春期。此外，哺乳动物体内GPR54的配体Kispeptin的中枢给药可以刺激GnRH和促性腺激素的释放。这些观察结果表明，Kispeptin对GnRH的释放有直接影响。这项建议的长期目标是更好地了解Gpr54和Kispeptin调节GnRH神经元在生殖能力发育和维持中的功能的分子机制。这项研究的中心假设是GPR54有助于GnRH神经元的发育，并调节下丘脑GnRH的释放。为了解决这一假设，我们提出了三个具体的目标：1)验证通过DNA微阵列分析确定的GPr54激活的特定基因靶点；2)分析Gpr54激活的细胞内信号转导通路，因为这些通路可能活跃在Kisspeptin刺激的GnRH释放或调控基因中；3)使用组织特异性基因敲除小鼠模型表征GPr54在体内GnRH神经元中的生理学意义。更详细地了解GPR54对GnRH神经元功能的调节对于促进我们对GnRH受体及其同源配体Kispeptin在生殖能力中的作用的了解是必要的。根据这项提议，候选人将在Ursula Kaiser博士的指导下接受密集的研究培训，使她能够在分子水平上发展成为生殖内分泌学领域的独立研究员所需的专业知识。这项工作的公共卫生意义在于，它的成功完成将指导开发新的创新方法来诊断和治疗影响生育能力的人类疾病，如青春期异常、多囊卵巢综合征、子宫内膜异位症和激素依赖型癌症，这些疾病每年共同影响数百万美国人。

DESCRIPTION (provided by applicant): The activation of gonadotropin-releasing hormone (GnRH) neurons is key to the successful initiation of puberty. However, the mechanisms by which this occurs are not well understood. Strong evidence supports a role for the kisspeptin-GPR54 system as a central contributor to this process. Humans and mice with inactivating mutations of the G protein-coupled receptor GPR54 have low gonadotropin levels and fail to undergo normal puberty. Also, the central administration of kisspeptin, the ligand of GPR54, in mammals stimulates the release of GnRH and gonadotropins. These observations suggest a direct effect of kisspeptin on GnRH release. The long-term goal of this proposal is to gain a better understanding of the molecular mechanisms by which GPR54 and kisspeptin regulate the function of the GnRH neuron in the development and maintenance of reproductive capability. The central hypothesis for this research is that GPR54 contributes to GnRH neuronal development and serves to regulate hypothalamic GnRH release. To address this hypothesis, three specific aims are proposed: 1) Validation of specific gene targets of GPR54 activation identified by DNA microarray analysis; 2) Analyze intracellular signal transduction pathways activated by GPR54 in GnRH neuronal cell cultures as these pathways may be active in kisspeptin-stimulated GnRH release or in regulated genes; and 3) Characterize the physiologic significance of GPR54 in GnRH neurons in vivo using a tissue-specific knockout mouse model. A more detailed understanding of GPR54 regulation of GnRH neuronal function is essential to advance our knowledge of the role of this receptor and its cognate ligand, kisspeptin, in reproductive competency. Under this proposal, the candidate will receive intensive research training under the mentorship of Dr. Ursula Kaiser, allowing her to develop the expertise needed to become an independent investigator in the field of reproductive endocrinology at the molecular level. The public health relevance of this work is that its successful completion will guide the development of new and innovative approaches to diagnosis and treatment of human diseases that affect fertility, such as abnormal puberty, polycystic ovarian syndrome, endometriosis, and hormone-dependent cancers that collectively affect millions of Americans annually.