THE ROLE OF EPSILON SUBUNIT IN GABAA RECEPTOR FUNCTION

描述：（申请人摘要） γ-氨基丁酸A型（GABAA）受体是主要的抑制剂， 大脑中的神经递质受体。全身麻醉药调节GABAA 受体通过一个未知的网站，人们普遍认为，这是他们的 作用机制。这一理论不可能通过一个 缺乏麻醉剂结合位点的拮抗剂。 GABAA受体各由5个亚基组成，已知有15种 这些多肽在哺乳动物中，提供了许多受体的潜力， 亚型不同的亚基组合可以形成不同的受体， 性质和整个大脑中的异质亚基分布 提供了GABAA受体对各种疾病的敏感性的区域差异， 治疗剂。GABAA受体对麻醉药的敏感性为 被认为缺乏亚基特异性，直到鉴定出一种新的 多肽（e）。e亚单位在大脑中有独特的分布， 可能赋予表达它的神经元新的特性。的确， 当该亚基与其它亚基结合形成细胞内的重组受体时， 这些GABAA受体表现出对麻醉剂调节的抗性。 e亚基与γ亚基共享大部分序列同一性，尽管 由这两种多肽赋予GABAA受体的性质相当 与众不同最值得注意的是γ亚基支持麻醉剂和苯二氮卓类药物 GABAA受体的调节，而e亚基则没有。 本项目旨在确定e亚单位在控制GABAA中的作用 受体功能亚基将用于定义氨基酸基序 参与麻醉剂对GABAA受体功能的调节。一个主要 该项目的目标是产生一个亚单位，可以在未来的研究中， 引入转基因小鼠，其将在功能上拮抗麻醉剂 GABAA受体的调节引起其他细胞的最小可能变化， GABAA受体特性。特异性aim 1将决定e亚基是否 取代GABAA受体的γ亚基。In Aim 2嵌合e/γ 2 结构将被用来探索结构和 这些亚基赋予的特性，特别强调识别 麻醉部位具体目标3将检查全身麻醉药是否 使用类似的机制来调节其他离子型受体的功能 与GABAA受体有关。特别强调的是5-HT 3 受体的这种受体是相当感兴趣的，因为它被认为是 几种止吐药的作用部位。人类同聚体和异聚体 5-HT 3受体由静脉麻醉剂丙泊酚调节， 据说有止吐作用

DESCRIPTION: (Applicant's Abstract) The gamma-aminobutyric type A (GABAA) receptor is the major inhibitory neurotransmitter receptor in the brain. General anesthetics modulate GABAA receptors through an unknown site and it is widely believed that this is their mechanism of action. This theory has been impossible to test by virtue of a lack of antagonists to anesthetic binding sites. GABAA receptors each consist of five subunits and there are 15 known varieties of these polypeptides in mammals, providing the potential for numerous receptor subtypes. Different subunit combinations can form receptors with distinct properties, and heterogeneous subunit distribution throughout the brain provides regional differences in the sensitivity of GABAA receptors to various therapeutic agents. The sensitivity of GABAA receptors to anesthetics was thought to lack subunit specificity until the identification of a new polypeptide (e). The e subunit has a distinctive distribution in the brain and may confer novel properties to the neurons in which it is expressed. Indeed, when the subunit is combined with others to form recombinant receptors in cell lines, these GABAA receptors exhibit a resistance to modulation by anesthetics. The e subunit shares most sequence identity with the gamma subunit, although the properties conferred to GABAA receptors by these two polypeptides are quite distinct. Most notably the gamma subunit supports anesthetic and benzodiazepine modulation of GABAA receptors while the e subunit does not. This project seeks to determine the role of the e subunit in controlling GABAA receptor function. The subunit will be used to define the amino acid motifs involved in the regulation of GABAA receptor function by anesthetics. A major goal of the project is to produce a subunit that can in future studies be introduced into transgenic mice which will functionally antagonize anesthetic regulation of GABAA receptors causing the minimum possible change in other GABAA receptor properties. Specific aim 1 will determine whether the e subunit displaces the gamma subunit from GABAA receptors. In Aim 2 chimeric e/gamma2 constructs will be used to probe the relationship between structure and the properties conferred by these subunits, with particular emphasis on identifying the anesthetic site. Specific aim 3 will examine whether general anesthetics use similar mechanisms to regulate the function of other ionotropic receptors related to the GABAA receptor. Particular emphasis will be placed on the 5-HT3 receptor. This receptor is of considerable interest as it is thought to be the site of action of several anti-emetic agents. Human homomeric and heteromeric 5-HT3 receptors are modulated by the intravenous anesthetic propofol which is reported to have anti-emetic properties.