INTERACTIONS AND ACTIVATION OF THE FSH RECEPTOR

FSH 受体的相互作用和激活

• 批准号: 6131705
• 负责人: Tae H. Ji
• 金额: $ 25.15万
• 依托单位: UNIVERSITY OF KENTUCKY
• 依托单位国家: 美国
• 财政年份: 1996
• 资助国家: 美国
• 起止时间: 1996-09-15 至 2004-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6131705
• 关键词: cyclic AMP; follicle stimulating hormone; glycoprotein structure; hormone receptor; inositol phosphates; intermolecular interaction; mutant; protein structure function; receptor binding; receptor expression; tissue /cell culture

The follicle stimulating hormone receptor (FSHR) and FSH play crucial roles in reproduction of mammal. Mutant FSHR and FSH are involved in fertility disorders, while FSHR and FSH are thought to be associated with ovarian and prostate cancers. Our long term goal is to understand the molecular mechanisms of FSHR's activities, which necessitates the study of interaction between FSHR and FSH and subsequent generation of signals for second messengers, cAMP and inositol phosphates. FSHR and other glycoprotein hormone receptors belong to a structurally unique subfamily of G protein-coupled receptors. They consist of the extracellular N-terminal half with approximately 350 amino acids (exodomain) and the membrane associated C-terminal half with an equal number of amino acids (endodomain). Since we and others reported, nearly ten years ago, that the exodomain is capable of high affinity hormone binding and signal generation, that the exodomain is the only high affinity binding site, and that the hormone/exodomain complex undergoes a conformation adjustment. Based on these observations we proposed that the hormone/exodomain complex interacts with the endodomain and this secondary interaction is responsible for signal generation. Lately, many of these have been verified and adopted by others. During the past grant period, we have reported a number of novel observations that hormone binding and signal generation of FSHR are distinct events, that exoloops in the endodomain constrain the FISH binding to the exodomain, and that FSH binding and cAMP induction work against each other and are compromised to maintain both activities at reasonable levels. Our preliminary findings suggest that the signals for cAMP and inositol phosphates are distinct, that the signals for inositol monophosphate, inositol biophosphate, and inositol triphosphate are also distinct, and that the putative Leu Rich Repeat motif in the exodomain is in need involved in FSH binding. Finally, we have found that the exodomain of one FSHR intermolecularly interacts with the endodomain of another FSHR, which has a significant implication in the understanding for the mechanism of multiple signal generation by not only FSHR but also other G protein coupled receptors. We propose to extend our observations (1) to determine the roles of individual amino acids in exoloops on hormone binding and induction of cAMP and three IP species, (2) to identify the contact points among the hormone, exodomain and endodomain, and (3) to conclusively demonstrate the intermolecular interaction of exodomain and endodomain and to examine the mechanisms. When successfully carried out, these studies will have far reaching consequences in understanding the underlying mechanisms of multiple signal generations by a FSHR as well as other receptors have significant implications in clinical and industrial applications.

卵泡刺激素受体（FSHR）和FSH在哺乳动物的繁殖中发挥着至关重要的作用。突变的 FSHR 和 FSH 与生育障碍有关，而 FSHR 和 FSH 被认为与卵巢癌和前列腺癌有关。我们的长期目标是了解 FSHR 活性的分子机制，这需要研究 FSHR 和 FSH 之间的相互作用以及随后产生第二信使 cAMP 和肌醇磷酸盐的信号。 FSHR 和其他糖蛋白激素受体属于结构独特的 G 蛋白偶联受体亚家族。它们由具有大约 350 个氨基酸的胞外 N 端半部（胞外域）和具有相同数量氨基酸的膜相关 C 端半部（胞内域）组成。自从我们和其他人在近十年前报道外结构域能够进行高亲和力激素结合和信号生成，外结构域是唯一的高亲和力结合位点，并且激素/外结构域复合物经历构象调整。基于这些观察，我们提出激素/外域复合物与内域相互作用，并且这种次级相互作用负责信号的产生。 最近，其中许多已被其他人验证和采用。在过去的资助期内，我们报告了许多新的观察结果，即激素结合和 FSHR 信号生成是不同的事件，内域中的外环限制 FISH 与外域的结合，并且 FSH 结合和 cAMP 诱导相互抵消并做出妥协以将这两项活动维持在合理水平。我们的初步研究结果表明，cAMP 和肌醇磷酸的信号是不同的，肌醇单磷酸、肌醇二磷酸和肌醇三磷酸的信号也是不同的，并且外域中推定的 Leu Rich Repeat 基序需要参与 FSH 结合。最后，我们发现一个 FSHR 的外域与另一个 FSHR 的内域发生分子间相互作用，这对于理解 FSHR 以及其他 G 蛋白偶联受体产生多重信号的机制具有重要意义。我们建议扩展我们的观察（1）以确定外环中单个氨基酸对激素结合和 cAMP 和三种 IP 物种诱导的作用，（2）确定激素、外结构域和内结构域之间的接触点，以及（3 ）最终证明外域和内域的分子间相互作用并检查其机制。一旦成功进行，这些研究将对理解 FSHR 以及其他受体产生多种信号的潜在机制产生深远的影响，并对临床和工业应用产生重大影响。