Regulation of Immediate Early Genes by GnRH in the Gonadotrope

描述（由申请人提供）：本申请的总体目标是确定垂体促性腺激素中GnRH诱导立即早期基因的机制，并确定其在促性腺激素β亚基表达的脉冲式GnRH调节中的作用。促性腺激素β亚基基因在垂体前叶促性腺激素细胞中特异性表达，以响应来自下丘脑的GnRH脉冲。它们是合成异二聚体糖蛋白、促黄体生成素（LH）和促卵泡激素（FSH）的限制因子。它们在整个月经周期中的差异表达对生殖功能至关重要。在这里，我们利用新的方法来描绘其差异表达的机制。我们建议分析立即早期基因c-Fos和Egr-1的表达和调节，这些基因被GnRH激活以诱导促性腺激素β基因的表达。在这三个目标的建议，我们将比较和对比这些立即早期基因的表达，以阐明其诱导的分子机制和LH与FSH β亚基基因的差异表达中的作用。在第一个目标中，我们将确定Egr-1和LH β最大表达与c-Fos和FSH β表达的最佳GnRH脉冲频率或幅度。在第二个和第三个目标，我们将分析的信号转导通路激活的促性腺激素释放激素，涉及的立即早期基因的表达，特别强调生理脉动促性腺激素释放激素。从这个R 03提案获得的结果将作出重大贡献，我们的分子机制，影响促性腺细胞中的基因表达的理解，并提供深入了解哺乳动物生殖系统的生理和病理生理。该申请的长期目标是提供关键结果，以建立基于PI先前在促性腺激素释放激素（GnRH）调节促性腺激素基因表达方面的成就的独立研究计划，并开发R 01应用程序。这个未来的R 01将建议扩大我们的理解，促性腺激素释放激素的促性腺激素释放激素的诱导机制，促性腺激素细胞中的立即早期基因的垂体中的基因表达的GnRH调节，以及这些基因在体内的功能，利用转基因小鼠。哺乳动物的生育力是通过调节促性腺激素基因的表达和分泌，在垂体促性腺激素细胞群水平上整合不同的调节信号来调节的。促性腺激素基因表达水平的功能障碍可导致病理生理障碍，如不孕症、性早熟、多囊卵巢综合征和低促性腺激素性功能减退症。因此，了解促性腺激素基因表达的分子机制将导致深入了解生殖系统的生理和病理生理学。

DESCRIPTION (provided by applicant): The overall goal of this application is to ascertain the mechanism of GnRH induction of immediate-early genes in the pituitary gonadotrope and determine their role in pulsatile GnRH regulation of the gonadotropin beta-subunit expression. Gonadotropin beta-subunit genes are specifically expressed in the anterior pituitary gonadotrope in response to GnRH pulses from the hypothalamus. They are the limiting factors in synthesis of the heterodimeric glycoproteins, luteinizing hormone (LH) and follicle-stimulating hormone (FSH). Their differential expression throughout the menstrual cycle is critical for reproductive function. Herein, we utilize novel approaches to delineate the mechanisms underlying their differential expression. We propose to analyze the expression and regulation of the immediate-early genes, c-Fos and Egr-1, that are activated by GnRH to induce expression of gonadotropin beta genes. In the three aims of this proposal, we will compare and contrast the expression of these immediate-early genes to elucidate the molecular mechanisms of their induction and their roles in differential expression of the LH versus FSH beta-subunit genes. In the first aim, we will determine optimal GnRH pulse frequency or amplitude for maximal expression of Egr-1 and LH beta versus the expression of c-Fos and FSH beta. In the second and third aims, we will analyze the signal transduction pathways activated by GnRH that are implicated in the expression of the immediate-early genes, with a special emphasis on physiologic pulsatile GnRH. Results obtained from this R03 proposal will make substantial contributions to our understanding of the molecular mechanisms that affect gene expression in the gonadotrope and provide insight into the physiology and pathophysiology of the mammalian reproductive system. A long-term goal of this application is to provide key results to establish an independent research program building on the PI's previous accomplishments in gonadotropin-releasing hormone (GnRH) regulation of gonadotropin gene expression and develop an R01 application. This future R01 will propose to expand our understanding of GnRH regulation of gene expression in the pituitary using genomics, the mechanisms of GnRH induction of immediate-early genes in the gonadotrope, and the function of these genes in vivo, utilizing genetically modified mice. Fertility in mammals is regulated by the integration of different regulatory signals that occurs at the level of the gonadotrope cell population in the pituitary gland, through modulation of gonadotropin gene expression and secretion. Dysfunction at the level of gonadotrope gene expression can lead to pathophysiologic disorders such as infertility, precocious puberty, polycystic ovarian syndrome, and hypogonadotropic hypogonadism. Thus, understanding the molecular mechanisms governing gonadotrope gene expression will lead to insight into the physiology and pathophysiology of the reproductive system.