ROLE OF CIRCADIAN GENE EXPRESSION IN GNRH PULSATILITY

下丘脑的促性腺激素释放激素(GnRH)的脉冲式分泌对包括人类在内的哺乳动物的正常生殖功能至关重要。虽然过去的许多研究都集中在什么神经和激素因素可能调节这种脉冲性释放，但调控这些事件发生时间的细胞和分子机制尚未阐明。最近的研究表明，转录反馈环可能对在多种细胞类型中发现的基因表达的昼夜振荡做出反应。然而，目前还不清楚昼夜节律基因是否也会影响GnRH基因的表达或分泌。有鉴于此，我们将利用GT1细胞和转基因小鼠在体外和体内研究mper1、mper2和Clock基因对GnRH基因表达和分泌的作用，具体目的如下：特定目的1确定是否可以诱导GT1细胞表达mper1的昼夜模式，以及mper1转录的任何变化是否与GnRH基因表达和/或肽分泌的同步化有关。特定目的2确定GT1细胞和转基因小鼠体内正常时钟信号的中断是否会影响GnRH基因表达和/或GnRH释放的模式和时间。这些研究的结果将有助于更好地了解正常生殖功能所需的GnRH脉动性分泌背后的可能分子和细胞机制。

The pulsatile secretion of gonadotropin-releasing hormone (GnRH) from the hypothalamus is crucial for normal reproductive function in mammals, including humans. Although much past research has concentrated on what neuronal and hormonal factors may modulate this pulsatile release, the cellular and molecular mechanisms regulating the timing of these events has yet to be elucidated. Recent studies suggest that a transcriptional feedback loop may be responsive for conferring circadian oscillations of gene expression found in multiple cell types. It is as yet unclear, however, whether circadian genes may also influence GnRH gene expression or secretion. Given this, we will investigate the role of the circadian genes mper1, mper2 and clock on GnRH gene expression and secretion in vitro using GT1 cells and in vivo using transgenic mice, as outlined in the following specific aims: Specific Aim 1 Determine whether GT1 cells can be induced to express a circadian pattern of mper1 expression, and whether any changes in transcription of mper1 are associated with the synchronization of GnRH gene expression and/or peptide secretion. Specific Aim 2 Determine whether disruption of normal CLOCK signaling in Vitro in GT1 cells, and in vivo in transgenic mice, affects patterns and timing of GnRH gene expression and/or GnRH release. Results from these studies will allow for a greater understanding of possible molecular and cellular mechanisms underlying the pulsatile secretion of GnRH required for normal reproductive function.