Targeting of Alpha7 nAChR for therapeutic effects

烟碱乙酰胆碱受体（nAChR）α 7亚型具有许多特性，这些特性使其区别于其它亚型。 nAChRs，包括神经递质ACh和普遍存在的组织因子胆碱的激活， 这可能与其在神经元和非神经元中的重要功能表达有关 细胞，包括免疫系统的细胞。在如此多样的组织中表达，a7 nAChR也被识别为 作为多种适应症的潜在重要治疗靶点， 疾病和精神分裂症，以及外周疾病，特别是炎性疾病和疼痛。 传统上，对α 7和其它nAChR的研究集中在激活或拮抗受体的配体上。 离子通道;然而，最近已经表明，治疗外周疾病的最佳药物 通过胆碱能抗炎通路（CAP）可能优先诱导替代性 与离子通道脱敏有关的构象状态。与假设一致， 外周疾病的A7受体的选择性靶向需要与治疗外周疾病的药物性质不同的药物。 CNS病症，介导炎症的α 7控制的细胞不具有具有可活化离子的α 7受体。 通道，可能是由于限制离子通道功能和赋予其他基因产物的共表达。 这些细胞中A7功能的不同药理学特征。我们用了电生理学， 生物化学和分子生物学方法来确定A7的多种构象状态如何 选择性地受配体调节，我们已经使用正变构调节剂（PAM）来鉴定新的 我们称之为沉默激动剂的分子这些沉默激动剂是弱的部分激动剂， 通道激活，但有效的CAP激活剂。此外，我们的研究变构激活剂（前- PAMs）和突变型受体不能被ACh或其他正构激动剂激活，导致了 一个变构激动剂结合位点和一类新的PAM依赖性通道配体的鉴定 激活剂也激活CAP。一个目的将是进一步表征与抗肿瘤药物一起工作的变构激活剂。 结构支架，我们已经确定，其中包括有效的小配体和MrIC芋螺毒素。的 芋螺毒素及其突变体将为设计另外的小配体提供模板。我们还将 开发基于新型锍基激动剂的新配体，该激动剂缺乏带电氮，并且应该具有 对神经炎性疼痛和疾病的适应症具有良好的脑穿透性。我们将测试我们的新配体 和先前在基于细胞的测定中鉴定的用于调节细胞因子产生的参比化合物 以及与炎性疾病和疼痛相关的信号转导介质。参比品数据 化合物将有助于确定新化合物的目标分布。具有所需细胞因子谱的新化合物 并且良好的预测药代动力学性质将被用于神经病的动物模型， 炎性疼痛。我们还将测试与可能差异调节的辅助蛋白相关的假设， A7在不同细胞类型中发挥作用。然后，我们将直接评估它们在体内减轻疼痛的功效， 炎症这些研究将使我们能够验证我们的核心假设，即A7的治疗靶向作用于 特定的适应症依赖于识别区分通道依赖性和通道依赖性的配体。 独立的信号模式。

The nicotinic acetylcholine receptor (nAChR) a7 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, a7 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 a7 and other nAChRs 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 through the cholinergic anti-inflammatory pathway (CAP) may preferentially induce the alternative conformational states associated with ion channel desensitization. Consistent with the hypothesis that the selective targeting of a7 receptors for peripheral disorders requires qualitatively different drugs from those for CNS disorders, cells that mediate a7 control of inflammation do not have a7 receptors with activatible ion channels, possibly due to the co-expression of other gene products that limit ion channel function and confer distinct pharmacological profiles for a7 function in those cells. We have used electrophysiological, biochemical, and molecular biological approaches to determine how the multiple conformational states of a7 are selectively regulated by ligands, and we have used positive allosteric modulators (PAMs) to identify novel molecules that we characterized as silent agonists. These silent agonists are weak partial agonists in regards to channel activation but effective activators of CAP. Additionally, our studies of allosteric activators (ago- PAMs) and mutant receptors that cannot be activated by ACh or other orthosteric agonists has led to the identification of an allosteric agonist binding site and a new class of ligands that are PAM-dependent channel activators that also activate CAP. One aim will be to further characterize allosteric activators working with the structural scaffolds that we have identified, which include both potent small ligands and MrIC conotoxin. The conotoxin and mutants thereof will provide a template for the design of additional small ligands. We will also develop new ligands based on a novel sulfonium-based agonist that lacks a charged nitrogen and should have good brain penetration for indications of neuro-inflammatory pain and disease. 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. Data on the reference compounds will help define a target profile for new compounds. New compounds with desired cytokine profiles and good predicted pharmacokinetic properties will be moved forward into animal models of neuropathic and inflammatory pain. We will also test hypotheses related to accessory proteins that may differentially regulate a7 function in different cell types. We will then 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 a7 for specific indications relies on identifying ligands that discriminate between channel-dependent and channel- independent signaling modes.