Endogenous G-Protein Coupled Receptor Antagonists

描述（由申请人提供）：Agouti-related protein（AGRP）和agglutamine（ASP）是迄今为止鉴定的仅有的两种天然存在的G蛋白偶联受体（GPCR）拮抗剂，当在小鼠中过度表达时，导致肥胖表型。肥胖症（身体质量指数>25）困扰着美国和其他国家的数百万人，并且是心脏病、II型糖尿病、中风和高血压的主要危险因素。在工业化国家中，肥胖问题由于暴饮暴食、高脂肪含量饮食和缺乏锻炼而变得更加复杂。在过去的几年里，已经发现了30多种参与和调节摄食行为和能量稳态的途径。黑皮质素途径包括源自前激素原阿黑皮素原（POMC）基因转录物的黑皮质素激动剂、迄今为止鉴定的五种黑皮质素受体（MC 1 R-MC 5 R）以及仅有的两种天然存在的GPCR拮抗剂，即阿格列汀（ASP）和刺豚鼠相关蛋白（AGRP）。在神经元中表达的四种黑皮质素遗传因子（POMC、AGRP、MC 3R和MC 4 R）已被鉴定为参与能量稳态。AGRP是MC 3R和MC 4 R的竞争性拮抗剂以及MC 4 R的反向激动剂。在诊断为神经性厌食症的人类中已经鉴定出AGRP多态性，其将AGRP与人类生理疾病状态联系起来。这些数据支持AGRP参与黑皮质素受体介导的神经药理学调节的假设。本申请的目的是a）设计和合成具有增加的受体亚型效力和/或选择性的配体，B）鉴定推定的配体-受体相互作用以合理设计潜在的治疗分子，和c）在小鼠中研究所选的分子。为了实现这些目标，我们将使用肽设计，组合库和GPCR诱变策略。此外，还将使用生物物理技术[2D 1H NMR和计算机辅助分子建模（CAMM）]，并将选定的化合物施用于野生型和MC 4 R敲除小鼠的脑和外周，以研究生理变化。公共卫生相关性：肥胖是一种复杂的疾病，是其他几种相关疾病的危险因素。黑皮质素途径已经在小鼠和人类中被确定，以调节肥胖。该研究项目旨在为合理设计分子提供知识，作为潜在的治疗药物，以预防或治疗与过度或进食不足相关的疾病。

DESCRIPTION (provided by applicant): Agouti-related protein (AGRP) and agouti (ASP) are the only two naturally occurring antagonists of G-protein coupled receptors (GPCRs) identified to date, and when over expressed in mice, result in an obese phenotype. Obesity (body mass index >25) afflicts millions of people in the United States and other countries, and is a major risk factor for heart disease, type II diabetes mellitus, stroke and hypertension. In industrialized countries, the problem of obesity is compounded by overeating, a high fat content diet, and a lack of exercise. The last few years have seen the characterization of over 30 pathways that have been identified to participate in and regulate feeding behavior and energy homeostasis. The melanocortin pathway includes the melanocortin agonists, derived from the preprohormone proopiomelanocortin (POMC) gene transcript, the five melanocortin receptors identified to date (MC1R-MC5R), and the only 2 naturally occurring antagonists of GPCRs, agouti (ASP) and agouti-related protein (AGRP). Four melanocortin genetic factors expressed in neurons (POMC, AGRP, MC3R, and MC4R) have been identified as being involved in energy homeostasis. AGRP is a competitive antagonist at the MC3R and MC4R as well as an inverse agonist at the MC4R. An AGRP polymorphism has been identified in humans diagnosed with anorexia nervosa, linking AGRP with a human physiological disease state. These data support the hypothesis that AGRP is involved in the regulation of melanocortin receptor mediated neuropharmacology. The aims of the current application are to a) design and synthesize ligands with increased receptor subtype potency and/or selectivity, b) identify putative ligand-receptor interactions for the rational design of potential therapeutic molecules, and c) study selected molecules in mice. To achieve these objectives, we will use peptide design, combinatorial libraries, and GPCR mutagenesis strategies. Additionally, biophysical techniques [2D 1H NMR and computer assisted molecular modeling (CAMM)] will also be used and selected compounds will be administered into the brain and periphery of wild type and MC4R knock out mice to study physiological changes. PUBLIC HEALTH RELEVANCE: Obesity is a complex disease and is a risk factor for several other associated diseases. The melanocortin pathway has been identified in mice and humans, to regulate obesity. This research project proposes to generate knowledge for the rational design of molecules as potential therapeutic agents to prevent or treat the diseases associated with over or under eating.