RESPONSES OF SUBPOPULATIONS OF MUSCARINIC RECEPTORS

毒蕈碱受体亚群的反应

基本信息

批准号：
6533725
负责人：
JOHN ELLIS
金额：
$ 21.08万
依托单位：
PENNSYLVANIA STATE UNIV HERSHEY MED CTR
依托单位国家：
美国
项目类别：
财政年份：
1985
资助国家：
美国
起止时间：
1985-02-01 至 2005-08-31
项目状态：
已结题

项目摘要

DESCRIPTION(Adapted from applicant's abstract): Muscarinic acetylcholine receptors belong to the very numerous class of heptahelical-receptors, but are unusual for this class in that they possess multiple extracellular binding sites. The present studies are designed to better understand muscarinic allosteric interactions from pharmacological and structural viewpoints. Dysfunction of muscarinic cholinergic systems in the brain contributes to the deficits associated with many illnesses, including Alzheimer's Disease. However, treatment with directly-acting muscarinic cholinergic drugs has not proven to be very beneficial to date. This may relate in part to the adverse effects and lack of selectivity of currently available muscarinic drugs. There are theoretical reasons why allosteric drugs can have inherent advantages of selectivity, efficacy, and safety over directly-acting (competitive) agents. For example, the allosterically-acting benzodiazopines enhance the action of the neurotransmitter GABA and are very effective and safe, even though directly-acting GABA agonists and reuptake inhibitors have no clinical use whatsoever. Although it has been known for some time that muscarinic receptors are susceptible to allosteric regulation only very recently have allosteric ligands been discovered that are positively cooperative with the endogenous agonist, acetylcholine. These first-generation ligands have relatively low affinities, but they demonstrate a potential for the development of drugs that are subtype-selective in terms of cooperativity, as well as affinity. The aims of this application are to apply approaches that we have developed in past studies to better understand the interactions between the receptors and allosteric ligands, especially these new ligands. These tools include: pharmacological model testing, to determine whether ligands interact solely with an allosteric site and whether different allosteric ligands act at a common site; and, molecular genetic techniques, to determine which structural features of the receptors are responsible for the subtype-selective binding and cooperativity of allosteric ligands. The hypothesis behind all of these studies is that subtype-selective ligands interact with specific residues that can be located through the use of mutagenic and chimeric studies. Once candidate residues have been identified by this process, the hypothesis that they are in fact involved in intimate contact with the ligand will be tested by making reciprocal mutations on different subtypes, by investigating the interaction of modified ligands with wild-type and modified receptors, and by inserting specific epitopes into non-muscarinic receptors. We expect that the results of these studies will benefit cholinergic pharmacology and also contribute to an understanding of the potential for allosteric modulation of other heptahelical receptors.

描述（改编自申请人的摘要）：毒蕈碱乙酰胆碱受体属于众多类别七螺旋受体，但对于此类受体来说很不寻常，因为它们具有多个细胞外结合位点。目前的研究旨在从药理和毒蕈碱变构相互作用更好地理解结构性观点。毒蕈碱胆碱能系统功能障碍大脑会导致与许多疾病相关的缺陷，包括阿尔茨海默病。然而，直接作用的毒蕈碱治疗迄今为止，胆碱能药物尚未被证明非常有益。这可能与部分原因是目前可用的药物的不利影响和缺乏选择性毒蕈碱类药物。变构药物可以发挥作用是有理论原因的与直接作用相比，具有选择性、有效性和安全性的固有优势（有竞争力的）代理商。例如，具有变构作用的苯二氮卓类药物增强神经递质 GABA 的作用，非常有效安全，尽管直接作用的 GABA 激动剂和再摄取抑制剂没有临床使用无论如何。尽管人们已经知道有一段时间了毒蕈碱受体仅对变构调节非常敏感最近发现了变构配体，其具有积极的意义与内源性激动剂乙酰胆碱合作。这些第一代配体的亲和力相对较低，但它们表现出潜在的开发在协同性方面具有亚型选择性的药物，还有亲和力。该应用程序的目的是应用以下方法我们在过去的研究中进行了开发，以更好地理解之间的相互作用受体和变构配体，尤其是这些新配体。这些工具包括：药理学模型测试，以确定配体是否相互作用仅具有变构位点以及不同的变构配体是否作用于一个公共站点；以及分子遗传学技术，以确定哪种结构受体的特征负责亚型选择性结合和变构配体的协同作用。所有这些研究背后的假设是亚型选择性配体与特定残基相互作用，这些残基可以通过使用诱变和嵌合研究来定位。曾经的候选人残留物已通过该过程被识别，假设它们位于与配体密切接触有关的事实将通过以下方法进行测试通过研究不同亚型的相互突变用野生型和修饰受体修饰配体，并通过插入将特定表位转化为非毒蕈碱受体。我们期望的结果是这些研究将有利于胆碱能药理学，也有助于了解其他七螺旋结构的变构调节潜力受体。