GABA Receptor Regulation by Splicing Truncation

通过剪接截断调节 GABA 受体

• 批准号: 6604870
• 负责人: DAVID R. BURT
• 金额: $ 14.85万
• 依托单位: UNIVERSITY OF MARYLAND BALTIMORE
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-05-01 至 2006-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6604870
• 关键词: GABA receptor; RNA splicing; RNase protection assay; cell line; electrophysiology; fluorescence microscopy; glycosylation; laboratory mouse; laboratory rat; polymerase chain reaction; protein folding; protein localization; protein structure function; receptor expression; site directed mutagenesis; tissue /cell culture; western blottings

DESCRIPTION (provided by applicant): The goal is to define the regulatory role of an unusual form of alternative splicing of GABAA receptor alpha4 subunits. GABA (gamma-aminobutyric acid) is the major inhibitory neurotransmitter in the brain. Its type A receptors, GABA-gated chloride channels, are the site of action of drugs used to treat alcohol withdrawal, epilepsy, insomnia, anxiety, etc., and are likely sites of action for alcohol itself. Many subunits (6 alpha, 3 beta, 3 gamma, delta, epsilon, pi, 3 rho, theta) have been cloned in mammals. The alpha4 subunit has been especially implicated in the actions of alcohol. The mRNAs for some subunits exhibit alternative splicing, further increasing subunit diversity. A puzzling form of splicing described for alpha5, alpha6, and rho1 subunits, where it is rare, creates short deletions in the bases coding for the N-terminal extracellular domain which make the resulting subunits nonfunctional. Recently we discovered a relatively common form of alternative splicing of the alpha4 subunit mRNA which, remarkably, creates a message missing everything except the first two coding exons and the last coding exon, with a frameshift between them. This pattern of splicing gives a severely truncated mRNA, not subject to nonsense-mediated mRNA decay, which codes for 2 possible proteins. A short piece of the N-terminus right after the signal peptide is the only one which seems to be made. The splicing is developmentally and regionally regulated. Electrophysiological data suggest that the truncated mRNA, when coexpresssed with the complete alpha4 subunit, selectively reduces currents due to the latter. We plan to explore further whether the truncated alpha4 protein plays a post-translational regulatory role in expression of GABAA receptors containing the alpha4 subunit. These studies may establish a novel and important mechanism of regulation of GABAA receptors responsive to alcohol.

描述（由申请人提供）： 目标是确定 GABAA 受体 α4 亚基的一种不寻常形式的选择性剪接的调节作用。 GABA（γ-氨基丁酸）是大脑中主要的抑制性神经递质。其A型受体，即GABA门控氯通道，是用于治疗酒精戒断、癫痫、失眠、焦虑等药物的作用位点，也可能是酒精本身的作用位点。许多亚基（6 α、3 β、3 γ、δ、epsilon、pi、3 rho、theta）已在哺乳动物中克隆。 α4 亚基与酒精的作用尤其相关。一些亚基的 mRNA 表现出选择性剪接，进一步增加了亚基多样性。 α5、α6 和 rho1 亚基的一种令人费解的剪接形式（这种情况很少见）会在编码 N 端胞外结构域的碱基中产生短删除，从而使所得亚基失去功能。最近，我们发现了一种相对常见的 α4 亚基 mRNA 选择性剪接形式，值得注意的是，它产生的信息丢失了除前两个编码外显子和最后一个编码外显子之外的所有内容，并且它们之间存在移码。这种剪接模式产生了严重截短的 mRNA，不会受到无义介导的 mRNA 衰减的影响，它编码 2 种可能的蛋白质。信号肽后面的一小段 N 末端似乎是唯一被制成的。剪接受到发育和区域的调节。电生理学数据表明，当与完整的 α4 亚基共表达时，截短的 mRNA 会选择性地降低后者导致的电流。我们计划进一步探讨截短的α4蛋白是否在含有α4亚基的GABAA受体的表达中发挥翻译后调节作用。这些研究可能会建立一种新颖且重要的调节 GABAA 受体对酒精反应的重要机制。