Targeting of alpha7 nAChR for therapeutic effects

 描述(申请人提供)：烟碱型乙酰胆碱受体(NAChR)α7亚型具有许多区别于其他nAChR的特性，包括由神经递质ACh和普遍存在的组织因子胆碱激活，这一特征可能与其在神经细胞和非神经细胞(包括免疫系统细胞)中的重要功能表达有关。在这些不同的组织中表达的α7nAChR也被认为是各种适应症的潜在重要治疗靶点，包括阿尔茨海默病和精神分裂症等中枢神经系统疾病，以及外周疾病，特别是炎症性疾病和疼痛。传统上，对α7和其他nAChR的研究主要集中在激活或拮抗受体离子通道的配体上；然而，最近的研究表明，治疗周围疾病的最佳药物可能是那些优先诱导与离子通道脱敏相关的替代构象状态的药物。与选择性靶向治疗外周疾病的α7受体将需要与治疗中枢神经系统疾病的药物本质上不同的假设一致，介导α7控制炎症的细胞没有带有可激活离子通道的α7受体，这可能是由于其他基因产物的共表达限制了这些细胞的离子通道功能，并为这些细胞中的α7功能提供了不同的药理学特征。我们已经使用电生理和生化方法来确定α7的多种构象状态是如何被配体选择性地调节的，并使用变构调节剂来识别我们表征为沉默激动剂的新分子。我们的数据表明，沉默的激动剂将有助于选择性地靶向α7受体治疗外周疾病，而具有离子通道效力的替代α7选择性激动剂可能更好地治疗中枢神经系统疾病。对特定适应症具有选择性的药物在用于治疗时不太可能产生交叉副作用。在这个项目中，我们将继续完善和发展这些概念，用于使用沉默的激动剂选择性靶向α受体，方法是测试与此类药物的新药效团(S)相关的假设，并进一步确定配体结合结构域中差异调节特定构象状态稳定的元件，包括那些在非神经细胞中活跃的信号转导元件。我们将测试与辅助蛋白相关的假设，这些辅助蛋白可能在不同类型的细胞中以不同的方式调节α7的功能。我们将测试我们的新配体 以及以前在基于细胞的分析中发现的参考化合物，用于调节与炎症、疾病和疼痛相关的细胞因子的产生和信号转导的介体。我们还将在体内直接评估它们在减轻炎症疼痛方面的效果。这些研究将使我们能够检验我们的核心假设，即针对特定适应症的α7的治疗靶向将依赖于识别区分通道依赖和通道非依赖信号模式的配体。

 DESCRIPTION (provided by applicant): The nicotinic acetylcholine receptor (nAChR) α7 subtype has numerous properties that distinguish it from other nAChRs, including activation by both the neurotransmitter ACh and the ubiquitous tissue factor choline, a feature that may be associated with its important functional expression in both neuronal and non-neuronal cells, including cells of the immune system. Expressed in such diverse tissues, α7 nAChR are also recognized as potentially important therapeutic targets for diverse indications including CNS disorders like Alzheimer's disease and schizophrenia, as well as peripheral disorders, especially inflammatory diseases and pain. Traditionally, study of α7 and other nAChR has focused on ligands that activate or antagonize the receptor's ion channel; however, it has recently been shown that the best drugs for treating the peripheral disorders may be those that preferentially induce the alternative conformational states associated with ion channel desensitization. Consistent with the hypothesis that the selective targeting of α7 receptors for peripheral disorders will require qualitatively different drugs from those for CNS disorders, cells which mediate α7 control of inflammation do not have α7 receptors with activatable ion channels, possibly due to the co-expression of other gene products that limit ion channel function and confer distinct pharmacological profiles for α7 function in those cells. We have used electrophysiological and biochemical approaches to determine how the multiple conformational states of α7 are selectively regulated by ligands and have used allosteric modulators to identify novel molecules we characterize as silent agonists. Our data indicate that silent agonists will be useful to selectively target α7 receptors for peripheral diseases, while alternative α7 - selectie agonists with ion channel efficacy may be better for CNS disorders. Drugs with selectivity for specific indications will be less likely to have crossover side effects when used therapeutically. In this project we will continue to refine and develop these concepts for selective targeting of α receptors with silent agonists by testing hypotheses related to a novel pharmacophore(s) for such drugs and by further identifying elements in the ligand binding domain that differentially regulate the stabilization of specific conformational states, including those which are active for signal transduction in non-neuronal cells. We will test hypotheses related to accessory proteins that may differentially regulate α7 function in different cell types. We will test our new ligands and previously identified reference compounds in cell- based assays for the regulation of cytokine production and mediators of signal transduction that are relevant to inflammatory disease and pain. We will also directly evaluate their efficacy in vivo for reducing pain from inflammation. These studies will allow us to test our core hypothesis that the therapeutic targeting of α7 for specific indications will rely on identifying ligands that discriminate betwee channel-dependent and channel-independent signaling modes.