基于B族GPCR蛋白晶体结构阐明GLP-1R跨膜区关键位点的功能

胰高血糖素样肽-1受体（GLP-1R）是当今公认的、最重要的抗糖尿病药物作用靶点之一，但针对GLP-1R的非肽类小分子药物开发难度颇大，其受体结构至今未获解析。我们在前期研究中解析了同为B族GPCR的胰高血糖素受体（GCGR）的三维结构，这为我们开展GLP-1R的相应研究提供了方向。基于GCGR结构和全长受体的分子动力学模型，我们构建了97个GLP-1R突变体，发现了19个新的显著影响配体结合和6个不影响配体结合但抑制cAMP信号的关键位点。本课题拟在进一步确认这些关键位点功能的基础上，通过检测其与不同配体的结合能力研究其配体选择性，明确突变受体与配体结合的具体位点。同时，通过研究突变受体对不同下游信号通路的影响即与G蛋白的结合特征，认识其信号转导的偏向性。本课题的开展对于深入理解GLP-1R的功能、解析其结构和后续药物开发具有重要的意义。

Glucagon-like peptide-1 receptor (GLP-1R) is one of the most important drug targets in diabetes treatment. Non-peptidic GLP-1R agonist has attracted much attention due to its oral bioavailability and longer half-life. However, this effort was hindered partially due to the lack of a crystal structure of its transmembrane domain. We have previously determined the three-dimensional atomic structure of the human glucagon receptor (GCGR) which belongs to the same subfamily in class B GPCRs as GLP-1R. Based on the crystal structure and molecular simulation studies of GCGR, we have designed, constructed and analyzed 97 mutant GLP-1Rs, and our preliminary results showed that 19 mutations significantly decreased binding affinity while other 6 only affected cAMP signaling. In this project, we aim at elucidating the effects of these mutant receptors on ligand selectivity and potential mechanisms involved in bias signaling, by use of different ligands and chemical probes. The outcome of this study will deepen our knowledge on GLP-1R function, facilitate its 3-D structure determination and aid in drug discovery.