神经肽及其受体在生物发育各个阶段对各种生理功能起重要的调控作用。最近通过反向药理学方法鉴定了神经肽26RFa是孤儿受体GPR103的内源配体。26RFa/ GPR103是RFa家族中发现最晚的一个成员,其生理作用及其信号转导机制都有待进一步阐明。我们从临床病例发现了GPR103点突变呈偏好性信号转导,还有我们前期数据表明Gq和Gi双偶联的GPR103仅通过Gq激活ERK1/2通路。本项目旨在我们前期研究基础上，一方面，应用我们GPCR功能活性检测平台研究Gq/Gi双偶联GPR103仅以Gq依赖信号通路激活ERK1/2和自然突变体偏好性信号转导的分子机制；另一方面，利用GPR103敲除大鼠模型，结合细胞和分子水平的研究，阐明GPR103对内分泌的调控及其机制。本项目是在已有的研究基础上展开的创新研究,以期阐明GPR103信号转导及其对内分泌调控的机制，为防治内分泌相关疾病提供新的策略和靶点。

Neuropeptides act as neurohormones, neurotransmitters and neuromodulators to exert a large array of biological activities through different developmental stages. RF26a, a neuropeptide with 26-amino acid residues possessing the Arg-Phe-NH2 (RFamide) motif at its C-terminus, has recently been identified as an endogenous ligand for orphan G protein-coupled receptor GPR103 by using reverse-pharmacological approach. 26RFa/GPR103 is the latest member of the RFamide peptide family, and further studies are clearly required to fully elucidate the functional significance and molecular mechanisms of the 26RFa/GPR103 pair. In our preliminary experiments, we demonstrated that Gq/Gi-dually coupled GPR103 signals to ERK1/2 via Gq-dependent cascade. In addition, two naturally occurred mutations identified from patients exhibited biased signaling. Therefore, the research objective of this proposal is, on the one hand, to elucidate the mechanisms involved in Gq/Gi-dually coupled GPR103-mediated ERK1/2 activation through Gq-dependent pathway and naturally occurred mutants-induced biased signaling based on our GPCR functional assay platform. On the other hand, we will further attempt to elucidate the physiological roles of GPR103 in the regulation of endocrine system using in vivo GPR103-knock-out rat model and in vitro cultured endocrine tissues and cells. This project is an innovative research, and a better understanding of physiological roles and molecular mechanisms of 26RFa/GPR103 may provide potential therapeutic strategies and targets for diagnosis and treatment of GPR103 -related endocrine diseases.