STRUCTURAL ELEMENTS OF NICOTINIC ACETYLCHOLINE RECEPTORS

最近，我们对这一现象的理解有了新的进展。 烟碱型乙酰胆碱受体在中枢神经系统损伤中的作用 大脑，而这些受体基因的克隆给了我们 研究这些受体详细分子机制的工具[L]。 已知尼古丁受体参与成瘾过程[2]， 并被认为会影响精神分裂症[3，4]。他们有 也被证明对认知过程和记忆很重要。 尼古丁激动剂正在被开发为治疗该疾病的药物 阿尔茨海默氏症的发病率[5]。同时也加深了对 尼古丁受体在脑功能中可能发挥的作用 来欣赏一下存在于多种受体亚型 大脑。这项提议将扩大我们对一个至关重要的 生理特性，即对二价离子的渗透性是受调节的 在受体亚型(即亚基组合)水平上，以及 就特定的蛋白质结构域而言。二价离子渗透率可能是 与学习和记忆相关的神经元可塑性所必需的 并可能产生潜在的兴奋性毒性。 我们将在非洲爪哇卵母细胞中表达克隆的尼古丁受体，并与 研究嵌合和突变的亚基，我们将鉴定分子 调节钙通透性的元素，以及分子 与受体的使用依赖抑制有关的元件。 通过评估调控元素之间的关系 二价离子渗透性，以及与敏感性有关的 对于特定的拮抗者，可以定义治疗方法 可以针对特定的功能重要的受体亚型，或者 在靶向的同时，避免那些对认知过程至关重要的受体 那些参与上瘾过程的人，或者选择性地阻止那些 可能会将细胞置于毒性风险中。 将进行受体生理学和药理学的分析 无论是在全细胞电流水平上，还是在详细研究方面 单通道属性。与之相关的一系列研究 双功能抑制剂将允许抑制结合的处置 待评估的受体复合体内的位置。 我们广泛的初步数据为我们提供了强有力的基础 从方法和候选序列的角度进行实验设计 重要的结构领域。我们有证据表明二价离子 通透性由肌肉受体的伽马亚基和 神经元受体的α5亚单位。这款车型将直接 用反义基因敲除实验来评估 这些亚基在天然受体中的功能影响。 这项提案中的实验将提供重要的新见解 大脑中的烟碱受体及其生物物理学意义 特性，它们作为治疗靶点的潜力，以及它们之间的关系 特定的功能特性和药物敏感性之间的关系。

Recently new advances have been made in our understanding of the functional roles which nicotinic acetylcholine receptors may play in the brain, and the cloning of the genes for these receptors has given us the tools to study the detailed molecular mechanism of these receptors [l]. Nicotinic receptors are known to be involved in addictive processes[2], and have been suggested to be affected in schizophrenia [3, 4]. They have also been shown to be important for cognitive processes and memory. Nicotinic agonists are being developed as therapeutics for the treatment of Alzheimer's dementia [5]. Along with an increased understanding of the functional roles that nicotinic receptors may play in brain function has come an appreciation for the multiple receptor subtypes that exist in the brain. This proposal will extend our understanding of how a crucial physiological property, the permeability to divalent ions, is regulated both on the level of receptor subtype (i.e. subunit combination) and also in terms of the specific protein domains. Divalent ion permeability may be required for the neuronal plasticity associated with learning and memory and may also create a potential for excitotoxicity. We will express cloned nicotinic receptors in Xenopus oocytes, and with the study of chimeric and mutant subunits, we will identify the molecular elements that regulate calcium permeability, as well as the molecular elements that are involved with use-dependent inhibition of the receptors. By evaluating the relationships between the elements that regulate divalent ion permeability, and those which are associated with sensitivity to specific antagonists it may be possible to define therapeutics which may target specific functionally important receptor subtypes, either to spare those receptors important for cognitive processes, while targeting those involved in addictive processes, or to selectively block those which may put cells at risk of toxicity. The analysis of receptor physiology and pharmacology will be carried out both at the level of whole-cell currents and in terms of a detailed study of single channel properties. The study of a related series of bifunctional inhibitors will permit the disposition of inhibitory binding sites within the receptor complex to be evaluated. Our extensive preliminary data has provided us with a strong basis for experimental design in terms of approaches and candidate sequences for important structural domains. We have evidence that divalent ion permeability is regulated by the gamma subunits of muscle receptors and the alpha5 subunits of neuronal receptors. This model will be directly evaluated with antisense knockout experiments directed at eliminating the functional influences of these subunits in native receptors. The experiments in this proposal will provide important new insights into the nicotinic receptors of the brain in terms of their biophysical properties, their potential as therapeutic targets, and relationships between specific functional properties and drug sensitivity.