GnRH-Regulated Transcriptome in the Gonadotrope

描述（由申请方提供）：促性腺激素中基因转录的调节是决定促性腺激素水平的关键调节步骤，因此可调节性腺功能。两性的配子发生和类固醇生成都由这两种激素控制，即来自垂体的促卵泡激素（FSH）和促黄体生成激素（LH），而这两种激素又由来自下丘脑的促性腺激素释放激素（GnRH）调节。GnRH调节促性腺激素合成通过诱导三个立即早期基因：ATF 3诱导？糖蛋白亚基，Egr-1诱导LH？亚基，AP-1诱导FSH？亚单位本申请的总体目标是确定促性腺激素释放激素调节的转录组组成的促性腺激素细胞中的这些立即早期基因。我们提出了两个互补的目标，从更全面的角度来剖析转录调控。在第一个目标中，我们将确定直接靶基因的补充，除了促性腺激素亚基，这些立即早期基因的ChIP芯片，这将使我们能够描绘的转录调控网络。已经通过表达阵列分析鉴定的由GnRH诱导的基因与通过ChIP芯片确定的这三种最高度诱导的转录因子的直接基因靶点的交叉将使我们的分析集中在最具功能的结合元件上。此外，这些数据集的重叠将识别其转录可能与促性腺激素类似地调节的基因。在第二个目标中，使用从促性腺激素衍生细胞的cDNA文库的双杂交筛选，我们将确定与ATF 3，Egr-1或AP-1相互作用的分子，特别强调辅激活子和辅抑制子。这些辅因子可能有助于三种促性腺激素亚基的差异表达。此外，我们将确定从第一个目标中选择的靶基因是否在其启动子中具有相似的结合位点组和/或需要相同的辅因子，这可能有助于调节其表达。这种方法将帮助我们三角形，从一个广泛的角度来看，促性腺激素亚基的差异调节，以及它是否是通过形成不同的复合物在各自的启动子，除了分析更全球性的调控基因转录的促性腺激素。这一提议的结果也将为研究染色质重塑和基础转录机制的激活开辟新的途径。公共卫生相关性：哺乳动物的生育力是由不同激素信号的整合调节的，这种整合发生在脑垂体中促性腺细胞群体的水平上。这种整合最终导致促性腺细胞中基因表达的精确协调调节，从而导致控制生殖的激素的微妙平衡。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): Regulation of gene transcription in the gonadotrope is a key regulatory step that determines the levels of gonadotropin hormones and therefore, regulates gonadal function. Gametogenesis and steroidogenesis in both sexes are controlled by these two hormones, follicle-stimulating hormone (FSH) and luteinizing hormone (LH) from the pituitary, which are, in turn, regulated by gonadotropin-releasing hormone (GnRH) from the hypothalamus. GnRH regulates gonadotropin synthesis through induction of the three immediate early genes: ATF3 induces the ? glycoprotein subunit, Egr-1 induces the LH? subunit, and AP-1 induces the FSH? subunit. The overall goal of this application is to determine the GnRH-regulated transcriptomes comprised of these immediate early genes in the gonadotrope cell. We propose two complimentary aims to dissect transcriptional regulation from a more comprehensive standpoint. In the first aim, we will determine the complement of direct target genes, in addition to gonadotropin subunits, of these immediate early genes by ChIP-chip, which will allow us to delineate the transcriptional regulatory network. The intersection of genes that are induced by GnRH, already identified by expression array analysis, and the direct gene targets of these three most highly induced transcription factors determined herein by ChIP-chip, will focus our analysis on the most functional binding elements. Furthermore, overlap of these data sets will identify the genes whose transcription may be regulated similarly to gonadotropins. In the second aim, using a two-hybrid screen of a cDNA library from gonadotrope-derived cells, we will identify molecules that interact with ATF3, Egr-1 or AP-1, with a special emphasis on coactivators and corepressors. These cofactors may contribute to differential expression of the three gonadotropin subunits. Additionally, we will determine whether selected target genes from the first aim have similar sets of binding sites in their promoters and/or require the same cofactors, which may contribute to regulation of their expression. This approach will help us triangulate, from a broad perspective, the differential regulation of the gonadotropin subunits and whether it is accomplished by formation of diverse complexes on their respective promoters, in addition to analyzing the more global regulation of gene transcription in the gonadotrope. The results from this proposal will also open new avenues to study chromatin remodeling and activation of basal transcriptional machinery. PUBLIC HEALTH RELEVANCE: Fertility in mammals is regulated by integration of different hormonal signals, which occurs at the level of the gonadotrope cell population in the pituitary gland. The integration ultimately results in the precisely orchestrated modulation of gene expression in the gonadotrope cell that leads to delicate balance of hormones that control reproduction. Thus, understanding the molecular mechanisms governing gonadotrope gene expression will lead to insight into the physiology and pathophysiology of the reproductive system.