The Role of GPR54 Signaling in Pubertal Disorders

GPR54信号在青春期疾病中的作用摘要/摘要本项目的长期目标是确定调节青春期开始和生殖成熟时间的因素。GPR54（一种g蛋白偶联受体）及其配体kisspeptin作为GnRH分泌的上游调节因子的鉴定导致了对其在生殖轴调节中的作用的深入研究。GPR54的失活突变导致青春期发育失败和不孕。相反，这种受体的早期刺激会引发小鼠的性早熟。我们的初步结果表明，GPR54在持续的kisspeptin刺激下脱敏并内化，并且在一名女性中枢性性早熟（一种女性发病率过高的疾病）患者中发现的GPR54氨基酸替换通过延迟受体的脱敏来增加GPR54的反应性。因此，我们假设GPR54信号传导和脱敏的时间对于其控制青春期和生殖的作用至关重要，并且GPR54中的氨基酸替换可能通过干扰信号传导或脱敏来影响其反应性，从而导致临床表现。虽然g蛋白偶联受体脱敏通常受到强烈调控，但尚未有关于GPR54脱敏的数据发表。该项目的短期目标是确定GPR54脱敏的机制，以了解该受体的基因突变如何影响这些机制，从而影响青春期发病和性成熟的时间。具体而言，本提案的目的是：(1)明确GPR54脱敏的机制，重点研究磷酸化和阻滞蛋白募集的作用；(2)明确GPR54内化的机制，重点研究了阻滞蛋白、动力蛋白和网格蛋白的作用；(3)确定内化GPR54的命运，以确定受体是否被引导到溶酶体降解或再循环回质膜。在每种情况下，将确定GPR54的两个突变对这些途径的影响，一个在性早熟患者中发现，另一个在促性腺功能减退症患者中发现。深入了解GPR54信号传导的机制可能揭示正常和异常青春期发育的性别差异的基础，并为治疗和预防青春期发育异常和其他生殖疾病提供一系列新的潜在药理调控靶点。该项目的目的是明确GPR54受体信号和脱敏调控的机制，以了解该受体的基因突变如何影响这些机制，从而影响青春期开始和性成熟的时间。这些研究有望为我们理解携带突变的患者生殖障碍的机制提供重要贡献。反过来，这些见解可能有助于未来通过操纵kisspeptin-GPR54信号系统来调节青春期时间的疗法的发展。

DESCRIPTION (provided by applicant): Role of GPR54 Signaling in Pubertal Disorders Summary/Abstract The long term goal of this project is to identify factors that regulate the timing of pubertal onset and reproductive maturation. The identification of GPR54, a G-protein coupled receptor, and its ligand, kisspeptin, as upstream regulators of GnRH secretion has led to intense research to elucidate their roles in the regulation of the reproductive axis. Inactivating mutations in GPR54 cause failure to undergo puberty and infertility. In contrast, early stimulation of this receptor triggers precocious puberty in mice. Our preliminary results indicate that GPR54 is desensitized and internalized in response to continuous kisspeptin stimulation, and that a GPR54 amino acid substitution identified in a female patient with central precocious puberty (a disorder with disproportionately high female incidence) increases GPR54 responsiveness by delaying the desensitization of the receptor. Thus, we hypothesize that the timing of signaling and desensitization of GPR54 is critical for its role in controlling puberty and reproduction, and that amino acid substitutions in GPR54 may affect its responsiveness by interfering with signaling or desensitization, thereby contributing to the clinical presentation. Although G-protein coupled receptor desensitization is generally strongly regulated, no data have been published on GPR54 desensitization. The short term goal of this project is to define the mechanisms underlying GPR54 desensitization, in order to understand how genetic mutations of this receptor affect these mechanisms and hence the timing of pubertal onset and sexual maturation. Specifically, the aims of this proposal are to: (1) Define the mechanisms of GPR54 desensitization, focusing on the roles of phosphorylation and arrestin recruitment; (2) Define the mechanisms of GPR54 internalization, focusing on the roles of arrestin, dynamin, and clathrin; and (3) Define the fate of the internalized GPR54, to determine whether the receptor is directed to lysosomal degradation or recycled back to the plasma membrane. In each case, the effects of two mutations in GPR54, one identified in a patient with precocious puberty, and the other in a patient with hypogonadotropic hypogonadism, on these pathways will be determined. A thorough understanding of the mechanisms underlying GPR54 signaling may uncover the basis of gender differences in normal and abnormal pubertal development, as well as reveal a new array of potential targets of pharmacological manipulation for the treatment and prevention of abnormal pubertal development and possibly other reproductive disorders. Role of GPR54 Signaling in Pubertal Disorders Narrative The goal of this project is to define the mechanisms underlying the regulation of GPR54 receptor signaling and desensitization, in order to understand how genetic mutations of this receptor affect these mechanisms and hence the timing of pubertal onset and sexual maturation. These studies are expected to offer important contributions to our understanding of the mechanisms underlying the reproductive disorders in the patients carrying the mutations. These insights, in turn, may contribute to future development of therapies designed to modulate the timing of puberty by manipulating the kisspeptin-GPR54 signaling system.