Targeting of alpha7 nAChR for therapeutic effects

 描述（由申请人提供）：烟碱乙酰胆碱受体（nAChR）α7亚型具有许多区别于其他nAChR的特性，包括通过神经递质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元和非神经元细胞（包括免疫系统细胞）中的重要功能表达相关。α7 nAChR在如此多样的组织中表达，也被认为是多种适应症的潜在重要治疗靶点，包括CNS疾病，如阿尔茨海默病和精神分裂症，以及外周疾病，特别是炎性疾病和疼痛。传统上，α7和其他nAChR的研究集中在激活或拮抗受体离子通道的配体上;然而，最近显示，治疗外周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。与外周疾病α7受体的选择性靶向治疗需要与CNS疾病不同的药物这一假设一致，介导α7炎症控制的细胞不具有可激活离子通道的α7受体，这可能是由于限制离子通道功能的其他基因产物的共表达，并赋予这些细胞中α7功能不同的药理学特征。我们已经使用电生理学和生物化学方法来确定α7的多种构象状态是如何被配体选择性调节的，并使用变构调节剂来鉴定我们表征为沉默激动剂的新型分子。我们的数据表明，沉默激动剂将有助于选择性靶向α7受体治疗外周疾病，而具有离子通道功效的替代α7选择性激动剂可能更适合治疗CNS疾病。对特定适应症具有选择性的药物在治疗上使用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，选择性靶向α受体与沉默激动剂，通过测试相关的假设，一个新的药效团（S）的这种药物，并通过进一步确定在配体结合域的差异调节特定构象状态的稳定性，包括那些活跃的非神经元细胞中的信号转导的元素。我们将检验与辅助蛋白相关的假设，这些辅助蛋白可能在不同细胞类型中差异调节α7功能。我们将测试我们的新配体 以及先前在基于细胞的测定中鉴定的用于调节与炎性疾病和疼痛相关的细胞因子产生和信号转导介质的参考化合物。我们还将直接评估它们在体内减轻炎症疼痛的疗效。这些研究将使我们能够验证我们的核心假设，即α7针对特定适应症的治疗靶向将依赖于识别区分通道依赖性和通道非依赖性信号传导模式的配体。

 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.