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）： 目的是定义GABAA受体Alpha4亚基的替代剪接形式的调节作用。 GABA（γ-氨基丁酸）是大脑中主要的抑制性神经递质。它的A型受体，GABA门控氯化物通道，是用于治疗戒酒，癫痫，失眠，焦虑等药物的作用部位，可能是酒精本身的作用部位。许多亚基（6个Alpha，3个Beta，3 Gamma，Delta，Epsilon，Pi，3 Rho，Theta）被克隆在哺乳动物中。 Alpha4亚基特别涉及酒精的作用。一些亚基的mRNA表现出替代剪接，进一步增加了亚基多样性。对于Alpha5，Alpha6和Rho1亚基所描述的一种令人困惑的剪接形式，在罕见的地方，在编码N端细胞外域的编码的基础上产生了短暂的缺失，从而使所得的亚基不正常。最近，我们发现了Alpha4亚基mRNA的替代剪接的一种相对常见的形式，它显着地创造了一条消息，除了前两个编码外显子和最后一个编码外显子之外，还缺少所有内容，并在它们之间进行了框架。这种剪接模式会产生严重截断的mRNA，不受废话介导的mRNA衰变，该mRNA衰变代码为2种可能的蛋白质。信号肽之后的N末端的一小部分是唯一制造的。剪接在发育和区域受到调节。电生理数据表明，当与完整的alpha4亚基共表达时，截短的mRNA有选择地降低了由于后者而导致的电流。我们计划进一步探索截短的α4蛋白是否在含有alpha4亚基的GABAA受体的表达中扮演翻译后调节作用。这些研究可能建立了一种对酒精反应的GABAA受体调节的新颖而重要的机制。