Identification of a novel bioactive peptide

描述(申请人提供)：G蛋白偶联受体(GPCRs)是人类基因组中最大的基因家族，为治疗药物积累了最成功的生化靶点。大约140个GPCR的天然配体是未知的，因此它们被称为“孤儿”受体。这些天然配体的鉴定构成了开始研究其功能的关键一步，并具有开发新型药物的潜力。我们已经开发出一种策略，通过在合适的细胞系中表达克隆的受体，并在添加组织提取物的部分后监测受体的激活，来分离这种天然配体。这一新策略最终将使我们能够提纯活性分子并确定它们的结构。在这一应用中，我们建议应用这一高度创新的技术来分离、鉴定和表征仍难以捉摸的孤儿受体BRS-3(BRS-3)的自然配体。BRS-3受体有望在整合和调节摄食的复杂生理过程中发挥重要作用，事实证明，缺乏BRS-3受体的小鼠会出现过度吞噬、代谢低下和肥胖的表型。该受体不与已知的两种哺乳动物蛙素受体亚型(Bb-1和BB-2)结合的蛙肽Neurmedin B和胃泌素释放肽结合。在分离天然配体后，我们将对BRS-3的药理作用进行表征，并对其进行研究。随后，我们建议在行为喂养实验中研究BRS-3配体，以确定其作用模式。BRS-3配体将被证明是回答功能意义和了解BRS-3系统在调节能量平衡中的生理作用的宝贵工具。

DESCRIPTION (provided by applicant): G protein-coupled receptors (GPCRs) constitute the largest gene family in the human genome and accumulate the most successful biochemical targets for therapeutic drugs. The natural ligands of about 140 GPCRs are unknown and they are thus called "orphan" receptors. Identification of these natural ligands forms the crucial step to start studying their function and holds the potential for development of novel pharmaceutical drugs. We have developed a strategy to isolate such natural ligands by expressing the cloned receptors in suitable cell lines and monitoring activation of the receptors after adding fractions of tissue extracts. This novel strategy will ultimately allow us to purify the active molecules and determine their structure. In this application, we propose to apply this highly innovative technique to isolate, identify and characterize the natural ligand of the orphan receptor bombesin subtype-3 (BRS-3) that is still elusive. BRS-3 receptor is expected to play an important role in integrating and modulating the complex physiology underlying feeding as evidenced by the fact that mice devoid of BRS-3 receptor are hyperphagic, hypometabolic and develop an obese phenotype. This receptor does not bind the two known mammalian bombesin counterparts of the frog peptide neuromedin B and gastrin-releasing peptide that bind to the other two bombesin receptor subtypes (BB-1 and 2). Following the isolation of the natural ligand, we will characterize the pharmacological effects, study the Subsequently, we propose to study the BRS-3 ligand in a behavioral feeding assay in order to determine its mode of action. The BRS-3 ligands will prove as an invaluable tool to answer the functional significance and understand the physiological role of the BRS-3 system in the regulation of energy balance.