The Role of GPR54 Signaling in Pubertal Disorders

描述(申请人提供)：GPR54信号在青春期疾病中的作用概述/摘要该项目的长期目标是确定调节青春期开始和生殖成熟的因素。G蛋白偶联受体GPR54及其配体Kispeptin被确定为GnRH分泌的上游调节因子，这使得人们对其在生殖轴调节中的作用进行了深入的研究。Gpr54的失活突变会导致无法经历青春期和不孕不育。相比之下，这种受体的早期刺激会触发小鼠的性早熟。我们的初步结果表明，GPR54对持续的Kispeptin刺激是脱敏和内化的，在中枢性早熟(一种女性发病率高得不成比例的疾病)女性患者中发现的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的信号和脱敏的时机对于其控制青春期和生殖的作用是至关重要的，并且GPR54中的氨基酸替换可能通过干扰信号或脱敏而影响其反应性，从而有助于临床表现。虽然G蛋白偶联受体的脱敏普遍受到强烈的调控，但关于Gpr54脱敏的数据还没有发表。该项目的短期目标是确定GPR54脱敏的潜在机制，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。具体地说，这项建议的目的是：(1)确定GPR54的脱敏机制，重点是磷酸化和arrestin募集的作用；(2)确定Gpr54的内化机制，重点是arrestin、Dynamin和clathrin的作用；以及(3)确定内化的GPR54的命运，以确定受体是直接作用于溶酶体降解还是循环回到质膜。在每一种情况下，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，另一个在性腺激素低减患者中发现。对GPR54信号转导机制的透彻理解可能揭示青春期发育正常和异常的性别差异的基础，并揭示一系列新的潜在的药物操纵靶点，用于治疗和预防青春期异常发育和可能的其他生殖疾病。GPR54信号在青春期疾病叙事中的作用本项目的目标是确定GPR54受体信号调节和脱敏的潜在机制，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潜在机制提供重要贡献。这些洞察力反过来可能有助于未来设计的治疗方法的发展，旨在通过操纵Kispeptin-Gpr54信号系统来调节青春期的时间。

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.