MECHANISMS OF GNRH RECEPTOR GENE EXPRESSION

GnRH释放、GnRH受体数量和 促性腺激素细胞合成和分泌LH和FSH的作用已被证实。 虽然对GnRH受体基因表达的了解相对较少， 促性腺激素，共同α-糖蛋白亚基基因的启动子 似乎是由多个反式作用的协同结合激活的 这些因子包括β-核受体、类固醇生成因子-1（SF-1）、 1）。 在转基因小鼠中SF-1基因的破坏导致， 其他的事情，减少了编码共同的α基因的表达， 以及LH和FSH的独特β亚基和GnRH受体。 最近， 我们已经证明，500个碱基对的近端启动子从GnRH 受体基因足以驱动荧光素酶的瞬时表达， 促性腺激素衍生的α T3细胞系的转染。 同样的 载体也被SF-1的过表达激活，减去其配体 结合域，在非促性腺细胞。 此外，瞬态 用含有一系列 从-500到-400的5'端缺失显示启动子的表达逐步减少， 活性指示由几个反式作用因子结合。 鉴于 在这些数据中，我们假设SF-1结合是必要的，但不是必需的。 足以促性腺激素释放激素受体基因的表达。 因此，本研究的目的是：1）确定SF-1是否 是GnRH受体启动子的完全基础活性所必需的;和2） 以确定其他必要的组成部分，为充分的基础活动， 促性腺激素 这些研究将有助于我们了解 促性腺激素基因表达和多种顺式作用的相互作用 赋予细胞特异性基因表达的元件。

The relationship between GnRH release, GnRH receptor numbers, and the synthesis and secretion of LH and FSH in gonadotropes is well established. While relatively little is known about GnRH receptor gene expression in gonadotropes, the promoter of the common alpha-glycoprotein subunit gene appears to be activated by cooperative binding of multiple trans-acting factors including the orphan-nuclear receptor, steroidogenic factor-1(SF- 1). Disruption of the SF-1 gene in transgenic mice resulted in, among other things, decreased expression of the genes encoding the common alpha and unique beta subunits of LH and FSH, and the GnRH receptor. Recently, we have shown that 500 basepairs of proximal promoter from the GnRH receptor gene are sufficient to drive luciferase expression in transient transfections of the gonadotrope-derived alphaT3 cell line. This same vector was also activated by overexpression of SF-1, minus its ligand binding domain, in non-gonadotrope cells. Furthermore, transient transfections of alphaT3 cells with reporter constructs containing serial 5' deletions from -500 to -400 revealed a stepwise decrease in promoter activity indicative of binding by several trans-acting factors. In light of these data, we hypothesize that SF-1 binding is necessary, but not sufficient for gonadotrope expression of the GnRH receptor gene. Therefore, the aims of this research proposal are: 1) to determine if SF-1 is necessary for full basal activity of the GnRH receptor promoter; and 2) to identify the other components necessary for full basal activity in gonadotropes. These studies will contribute to our understanding of gonadotrope gene expression and the interactions of multiple cis-acting elements to confer cell-specific gene expression.