Clay C M, Nelson S E, Digregorio G B, Campion C E, Wiedemann A L, Nett R J
Animal Reproduction and Biotechnology Laboratory, Department of Physiology, Colorado State University, Fort Collins, 80523, Colorado, USA.
Endocrine. 1995 Aug;3(8):615-22. doi: 10.1007/BF02953028.
Gonadotropin-releasing hormone (GnRH) is a decapeptide produced by the hypothalamus. Upon binding to specific high-affinity receptors on gonadotrope cells of the anterior pituitary gland, GnRH stimulates the synthesis and secretion of LH. In light of the critical role of GnRH in reproduction much effort has been directed toward understanding the regulation of this hormone and its cognate receptor. The recent availability of genomic clones for the GnRH receptor has facilitated research to address the molecular mechanisms underlying regulation of GnRH receptor gene expression. We have expanded the analysis of the promoter for the mouse GnRH receptor gene and report that in addition to transcriptional start sites located within 100 bp of the translation start codon there is a more distal transcriptional start site approximately 200 bp 5' of the initiation codon. The initiation of transcription from this more distal site was sufficient to confer cell-specific expression on luciferase. Further, transient expression assays of constructs containing progressive 5' deletions in the GnRH receptor gene promoter reveal the presence of one or morecis-acting elements located between -500 and -400 (relative to ATG) necessary for transcriptional activity in the gonadotrope-derived αT3 cell line. Finally, αT3 but not COS-7 cell nuclear extract contained protein(s) that bind to at least two separate motifs contained within the -500 to -400 region. We suggest that activation of GnRH receptor gene expression in the αT3 cell line requires the binding of at least two transcriptional regulatory proteins to basal enhancer elements located within a 100 bp region between -500 to -400 relative to the translation start codon in the mouse GnRH receptor gene.
促性腺激素释放激素（GnRH）是一种由下丘脑产生的十肽。GnRH与腺垂体促性腺激素细胞上的特异性高亲和力受体结合后，会刺激促黄体生成素（LH）的合成与分泌。鉴于GnRH在生殖过程中的关键作用，人们付出了诸多努力来了解这种激素及其同源受体的调控机制。GnRH受体基因组克隆的近期可得性促进了相关研究，以探讨GnRH受体基因表达调控的分子机制。我们扩展了对小鼠GnRH受体基因启动子的分析，并报告称，除了位于翻译起始密码子100 bp范围内的转录起始位点外，在起始密码子5'端约200 bp处还有一个更远端的转录起始位点。从这个更远端位点开始的转录足以赋予荧光素酶细胞特异性表达。此外，对GnRH受体基因启动子中含有逐步5'端缺失的构建体进行瞬时表达分析，结果显示在促性腺激素细胞来源的αT3细胞系中，转录活性所需的一个或多个顺式作用元件位于-500至-400（相对于ATG）之间。最后，αT3细胞核提取物而非COS-7细胞核提取物含有能与-500至-400区域内至少两个不同基序结合的蛋白质。我们认为，αT3细胞系中GnRH受体基因表达的激活需要至少两种转录调节蛋白与位于小鼠GnRH受体基因翻译起始密码子-500至-400之间100 bp区域内的基础增强子元件结合。
