MOLECULAR MECHANISMS OF GNRH ACTION

本研究的长期目标是更好地了解脉冲促性腺激素释放激素（GnRH）调节促黄体生成激素（LH）和促卵泡激素（FSH）亚单位基因表达的分子机制。促性腺激素（LH和FSH）释放的精确时间对于控制性发育和生殖功能至关重要。LH和FSH由垂体促性腺激素在下丘脑肽GnRH的调节下合成和分泌。GnRH被释放。以脉冲方式释放，释放频率随发育和整个月经或发情周期而变化。LH和FSH的生物合成和分泌受到GnRH脉冲频率变化的不同调节。这些GnRH频率变化激活的信号转导通路特异性调节促性腺激素亚单位基因的表达仍然知之甚少。目前的研究建议的重点是阐明参与介导不同GnRH脉冲频率对LH和FSH亚基基因表达的差异效应的信号转导途径。使用最近开发的，促性腺激素衍生的LbetaT 2细胞系暴露于GnRH在不同的GnRH脉冲频率，我们计划研究G蛋白α亚基，G蛋白，β/γ亚基，和信号转导通路下游的这些G蛋白激活，在这种差异调节的作用。最终，我们将在原代大鼠垂体细胞培养中进行验证性研究，以验证我们发现的生理相关性。此外，最近在生育能力降低和特发性低促性腺激素性性腺功能减退症（IHH）患者中发现了GnRH中的几种天然突变。我们建议检查这些新发现的突变对GnRH信号的影响，并将其与GnRH刺激的促性腺激素亚单位基因表达的影响相关联。这些突变的鉴定和功能特征将为研究GnRH作用途径提供临床相关和重要的背景。总之，这些研究将提供新的见解促性腺激素的调节机制，促性腺激素释放激素，这反过来又会导致更好地了解生殖发育，并可能指导新的和创新的治疗生殖功能障碍的发展。

The long-term objective of this proposal is to gain a better understanding of the molecular mechanisms of regulation of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) subunit gene expression by pulsatile gonadotropin-releasing hormone (GnRH). The precise episodic timing of the release of the gonadotropins, LH and FSH, is pivotal for the control of sexual development and reproductive function. LH and FSH are synthesize and secreted from pituitary gonadotropes under regulation by the hypothalamic peptide, GnRH. GnRH is released. is released in a pulsatile fashion with the frequency of release varying developmentally and throughout the menstrual or estrous cycle. LH and FSH biosynthesis and secretion are differentially regulated by these changes in GnRH pulse frequency. The signal transduction pathways that are activated by these changes in GnRH frequency to specifically regulated the expression of the gonadotropin subunit genes remain poorly understood. The present research proposal focuses on the elucidation of the signal transduction pathways involved in mediating the differential effects of varying GnRH pulse frequencies on LH and FSH subunit gene expression. Using the recently developed, gonadotrope-derived LbetaT2 cell line exposed to GnRH at varying GnRH pulse frequencies, we plan to study the roles of G-protein alpha subunits, G-protein, beta/gamma subunits, and signal transduction pathways downstream of an activated by these G-proteins, in this differential regulation. Ultimately, we will perform confirmatory studies in primary rat pituitary cell cultures to validate the physiologic relevance of our findings. In addition, several naturally occurring mutations in the GnRH have been identified recently in patients with reduced fertility and idiopathic hypogonadotropic hypogonadism (IHH). We propose to examine the effects of these newly identified mutations on GnRH signaling and to correlate them with effects on GnRH-stimulated gonadotropin subunit gene expression. The identification and functional characterization of these mutations will provide a clinically relevant and important context in which to study pathways of GnRH action. Taken together, these studies will provide new insights into the mechanisms of regulation of gonadotropins by GnRH, which will, in turn, lead to a better understanding of reproductive development, and may guide the development of new and innovative therapies for disorders of reproductive function.