Regulation of GnRH receptor signaling by lipid rafts

说明书(申请人提供)：促性腺激素释放激素(GnRH)通过与其在垂体促性腺激素表面的同源受体结合，刺激黄体生成素和卵泡刺激素的合成和分泌而发挥其生物学效应。在分子水平上，GnRH受体的参与启动了一系列复杂的信号事件，包括丝裂原活化蛋白激酶(MAPK)通路的激活；这种激活是诱导几个促性腺激素功能所必需的基因所必需的。因此，了解GnRH诱导的MAPK信号的调控在生殖内分泌学中具有重要意义。调节信号通路的一种机制涉及信号分子通过与被称为脂筏的特殊质膜结构域的联系而亚细胞区隔。脂筏是富含胆固醇和鞘磷脂的膜域，具有不同的生物物理性质，已被证明是组装多蛋白信号复合体的平台。在这里，我们提供了GnRH受体以及关键的MAPK信号分子与小鼠αT3-1促性腺激素细胞系中的脂筏相关的初步证据。这项建议概述了一系列实验，旨在测试这一假设，即脂筏通过促进可定义的MAPK信号模块的分区组装来调节GnRH诱导的促性腺激素中的MAPK信号。我们将使用各种生化、分子和细胞生物学技术来研究脂筏在GnRH诱导的AlphaT3-1细胞中的MAPK信号中的作用，以及在初级分化的小鼠促性腺激素中的作用。

DESCRIPTION (provided by applicant): Gonadotropin-releasing hormone (GnRH) exerts its biological effects by binding to its cognate receptor on the surface of pituitary gonadotropes and stimulating the synthesis and secretion of luteinizing hormone and follicle-stimulating hormone. At the molecular level, engagement of the GnRH receptor initiates a complex series of signaling events including activation of the mitogen-activated protein kinase (MAPK) pathways; this activation is required for the induction of several genes essential for gonadotrope function. Understanding the regulation of GnRH-induced MAPK signaling is thus of great importance in reproductive endocrinology. One mechanism by which signaling pathways are regulated involves subcellular compartmentalization of signaling molecules through their association with specialized plasma membrane domains called lipid rafts. Lipid rafts are cholesterol and sphingolipid rich membrane domains with distinct biophysical properties that have been shown to function as platforms for the assembly of multi-protein signaling complexes. Here we provide preliminary evidence that the GnRH receptor as well as key MAPK signaling molecules are associated with lipid rafts in the murine alphaT3-1 gonadotrope cell line. This proposal outlines a set of experiments designed to test the hypothesis that lipid rafts regulate GnRH-induced MAPK signaling in gonadotropes by facilitating the compartmentalized assembly of definable MAPK signaling modules. We will use a variety of biochemical, molecular, and cell-biological techniques to study the role of lipid rafts in GnRH-induced MAPK signaling both in alphaT3-1 cells, as well as in primary differentiated mouse gonadotropes.