Functional analysis of a newly identified ligand and search for novel bioactive peptides associated with regulation of feeding behavior.

肥胖是世界范围内最严重的问题之一，因为它与生活方式相关的疾病，如高血压、心血管疾病和2型糖尿病有关。本研究旨在发现与能量平衡和摄食行为调节相关的新型生物活性肽，并阐明其生物化学和病理生理意义。2005年，我们在大鼠脑中发现了一种新的生物活性肽，神经medin S (NMS)，作为G蛋白偶联受体（gpcr） FM-3/GPR66和FM-4/TGR-1的内源性配体。NMS与厌氧性神经肽neuromedin U （NMU）具有相同的受体结合核心结构。脑室内给药NMS对大鼠的摄食抑制作用强于NMU。弓形核α-MSH和室旁核CRH参与了NMS对摄食的作用。此外，我们还分离到了欧亚bombinid蟾蜍的NMS，表明NMS和NMU基因在两栖类水平上已经分化。胃饥饿素（Ghrelin）是从胃中纯化出来的一种新型肽，作为生长激素促分泌受体（GHS-R）的内源性配体，是一种刺激食物摄入的酰基化肽。我们发现母体的饥饿素在妊娠后期调节胎儿发育，去酰基饥饿素通过与GHS-R不同的受体相互作用刺激大鼠的摄食，并且饥饿素和去酰基饥饿素都参与胎儿脊髓的神经发生。为了寻找与摄食行为调节相关的新肽，我们建立了20个稳定表达孤儿gpcr的细胞系，并开发了利用生物发光共振能量转移（BRET）和受体内化的新方法。

Obesity is one of the most serious problems worldwide, because it is associated with lifestyle-related disease such as hypertension, cardiovascular disease and type 2 diabetes. The aims of this study are to identify novel bioactive peptides associated with regulation of energy balance and feeding behavior, and to clarify the biochemical and pathophysiological significance of the peptides.In 2005, we identified a novel bioactive peptide, neuromedin S (NMS), in rat brain as an endogenous ligand for the G protein-coupled receptors (GPCRs) FM-3/GPR66 and FM-4/TGR-1. NMS has same core structure essential for receptor binding as anorexigenic neuropeptide, neuromedin U (NMU). Intracerebroventricular (ICV) administration of NMS in rats induced more potent suppression of feeding than that of NMU. α-MSH in the arcuate nucleus and CRH in the paraventricular nucleus were involved in NMS action on feeding. Furthermore we isolated NMS of Eurasian bombinid toads, indicating that NMS and NMU genes had already diverged at the level of the Amphibia.Ghrelin, a novel peptide purified from stomach as an endogenous ligand for the growth hormone secretagogue receptor (GHS-R), is an acylated peptide that stimulates food intake. We showed that maternal ghrelin regulates fetal development during the late stages of pregnancy, ICV administration of des-acyl ghrelin to rats stimulates feeding through interactions with a receptor distinct from the GHS-R, and both ghrelin and des-acyl ghrelin are involved in neurogenesis of the fetal spinal cord.In order to search for novel peptides associated with regulation of feeding behavior, we established twenty cell lines stably expressing orphan GPCRs, and developed new methods using BRET (Bioluminescence Resonance Energy Transfer) and receptor internalization.