特异阻断α3β4烟碱型乙酰胆碱受体的α-芋螺毒素[S9K]TxID的受体结合分子机制与药效学研究

烟碱型乙酰胆碱受体α3β4亚型是治疗药物依赖和成瘾、肺癌、过度饮食和肥胖等的潜在靶点。以往发现的针对该受体亚型的特异性配体分子很少，且都存在作用主受体不是α3β4亚型、区分度低或活性差等问题。我们团队发现的α-芋螺毒素TxID是α3β4亚型的强阻断剂，在此基础上进行结构改造，获得了优化突变体[S9K]TxID。难能可贵的是，它能够高效专一性作用于α3β4亚型，IC50仅为6.9 nM，而对其他亚型无活性，是迄今针对α3β4受体选择性最好、活性最强的特异阻断剂。但[S9K]TxID与α3β4受体相互作用的分子机制尚不清楚，且其药效学特征未知。本项目拟综合利用受体定点诱变、电生理活性检测、分子动力学模拟、动物成瘾模型的建立和应用等方法，阐明[S9K]TxID对受体选择性结合的分子机理，并获知其对成瘾顽疾的治疗效果，这将为[S9K]TxID开发为工具药和戒烟戒毒原创海洋新药提供研究基础。

α3β4 nicotinic acetylcholine receptor (nAChR) is a potential therapeutic target for the treatment of drug dependence and addiction, lung cancer, overeat and obesity, etc. Very few selective ligands targeting α3β4 nAChR have been identified previously, which all have the disadvantages of not mainly targeting α3β4 subtype, poor activity and selectivity. Depending on the structure modification of α-conotoxin TxID which is an potent inhibitor of α3β4 nAChR identified in our lab, [S9K]TxID is obtained as an optimized mutant. It is most valuable that [S9K]TxID only exhibits inhibition on α3β4 nAChR with an IC50 of 6.9 nM, while has no obvious effect on other nAChR subtypes. So [S9K]TxID could be the most potent and selective antagonist for α3β4 nAChR so far. But the molecular mechanism of [S9K]TxID binding with α3β4 nAChR and its pharmacodynamical effects are still unknown. In this project, the approaches of site-directed receptor mutation, electrophysiological assessment, molecular dynamics simulation, establishment and application of animal addiction model will be comprehensively utilized, aiming at determining the molecular mechanism of receptor binding of [S9K]TxID, as well as evaluating its therapeutic effects on drug addiction. It will provide a research basis for the development and application of [S9K]TxID as a tool medicine, and also a new marine drug lead for smoking cessation and drug abstinence.