Department of Pediatrics, Division of Endocrinology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21287, USA.
J Neurosci. 2011 Mar 2;31(9):3336-43. doi: 10.1523/JNEUROSCI.5419-10.2011.
Appropriate tissue-specific gene expression of gonadotropin-releasing hormone (GnRH) is critical for pubertal development and maintenance of reproductive competence. In these studies, a common element in the mouse GnRH (mGnRH) promoter, between -2806 and -2078 bp, is shown to mediate differential regulation of hypothalamic and ovarian mGnRH expression. To further characterize this region, we generated a knock-out mouse (GREKO(-/-)) with a deletion of the mGnRH promoter fragment between -2806 and -2078 bp. GnRH mRNA expression in the brain of GREKO(-/-) was less than the expression in wild-type mice; however, immunohistochemical analysis revealed no difference between the numbers of GnRH neurons among groups. GnRH mRNA expression in the ovary was fivefold higher in GREKO(-/-). The immunohistochemical staining for GnRH in the ovary increased in surface epithelial and granulosa cells and also in the corpora lutea of GREKO(-/-) mice. The reproductive phenotype revealed that the mean day of vaginal opening was delayed, and additionally, there was a significant decrease in the length of proestrus and diestrus-metestrus phases of the estrous cycle, resulting in a shortened estrous cycle in GREKO(-/-) mice. This work supports the hypothesis that the region of the GnRH promoter contained between -2806 and -2078 bp acts as a cell-specific enhancer in the GnRH neuron and as a repressor in the ovary. Deletion of this region in vivo implicates the GnRH promoter in mediating pubertal development and periodic reproductive cycling, and forms the foundation to define the nuclear proteins important for puberty and estrous cycling in mammals.
促性腺激素释放激素（GnRH）的适当组织特异性表达对于青春期发育和生殖能力的维持至关重要。在这些研究中，显示在 -2806 至-2078bp 之间的小鼠 GnRH（mGnRH）启动子的共同元件介导了下丘脑和卵巢 mGnRH 表达的差异调节。为了进一步表征该区域，我们生成了一种 GnRH 启动子片段在 -2806 至-2078bp 之间缺失的敲除小鼠（GREKO(-/-)）。GREKO(-/-) 大脑中的 GnRH mRNA 表达低于野生型小鼠；然而，免疫组织化学分析显示各组 GnRH 神经元数量无差异。GREKO(-/-) 卵巢中的 GnRH mRNA 表达增加了五倍。GREKO(-/-) 小鼠卵巢中 GnRH 的免疫组织化学染色在表面上皮细胞和颗粒细胞中增加，并且在黄体中也增加。生殖表型表明阴道开口的平均天数延迟，并且发情周期的发情前期和发情后期-间情期阶段的长度显著减少，导致 GREKO(-/-) 小鼠的发情周期缩短。这项工作支持这样的假设，即在 -2806 至-2078bp 之间的 GnRH 启动子区域在 GnRH 神经元中作为细胞特异性增强子起作用，在卵巢中作为抑制剂起作用。该区域在体内的缺失暗示 GnRH 启动子参与调节青春期发育和周期性生殖循环，并为确定在哺乳动物中参与青春期和发情周期的核蛋白奠定了基础。
