Alcohol actions on NMDA receptor gating domains

描述（由申请人提供）：大脑中的N-甲基-D-天冬氨酸（NMDA）谷氨酸受体离子通道是酒精行为效应的重要介质。虽然已知酒精通过影响离子通道门控来抑制NMDA受体，但其作用的分子位点和这种作用的机制尚未确定。先前的研究已经指出了神经递质门控离子通道的跨膜结构域在酒精作用中的作用。该实验室的结果表明，NMDA受体NR 2A亚基的第四个膜相关（M）结构域中的保守甲硫氨酸残基（Met 823）深刻影响离子通道门控。最近在该实验室获得的证据表明，NR 2A（Met 823）也影响酒精敏感性的受体的方式是一致的酒精作用的网站，和相邻的残基也可能影响离子通道门控和酒精敏感性。在拟定研究中待检验的主要假设是，该残基和也参与离子通道门控的相邻残基形成了NMDA受体离子通道上酒精作用的关键位点。这些研究将结合全细胞和单通道膜片钳电生理记录来研究以下具体目的：1）NR 2A（Met 823）邻近区域在NMDA受体离子通道门控和酒精敏感性调节中的作用; 2）这些区域是否构成酒精作用于NMDA受体的关键位点; 3）酒精与这些位点相互作用以改变NMDA受体离子通道门控的精确动力学机制;以及4）在非神经元细胞系中观察到的NMDA受体突变对门控动力学和酒精调节的影响是否也在CNS神经元中观察到。这些研究的结果将产生重要的信息，酒精调制的NMDA受体的分子机制，新的见解的结构和功能的NMDA受体离子通道，以及更好地理解的方式，其中醇和类似的分子与蛋白质相互作用一般。由于NMDA受体在认知，运动功能和记忆中具有重要和广泛的作用，并且对酒精的主观效应及其CNS神经系统效应都有重要贡献，因此这些研究中获得的信息将代表理解酒精对神经系统影响的重要一步。

DESCRIPTION (provided by applicant): N-methyl-D-aspartate (NMDA) glutamate receptor-ion channels in the brain are important mediators of the behavioral effects of alcohol. Although alcohol is known to inhibit NMDA receptors by influencing ion channel gating, its molecular site of action and the mechanism underlying this effect have not been established. Previous studies have pointed to a role of the membrane-spanning domains of neurotransmitter-gated ion channels in the actions of alcohol. Results from this laboratory have shown that a conserved methionine residue (Met823) in the fourth membrane-associated (M) domain of the NMDA receptor NR2A subunit profoundly influences ion channel gating. Recent evidence obtained in this laboratory has shown that NR2A(Met823) also affects alcohol sensitivity of the receptor in a manner that is consistent with a site of alcohol action, and that adjacent residues may also influence both ion channel gating and alcohol sensitivity. The main hypothesis to be tested in the proposed studies is that this residue and adjacent residues that are also involved in ion channel gating form a key site of alcohol action on the NMDA receptor-ion channel. These studies will incorporate whole-cell and single-channel patch-clamp electrophysiological recording to investigate the following specific aims: 1) the role of domains adjacent to NR2A(Met823) in the regulation of NMDA receptor ion channel gating and alcohol sensitivity; 2) whether these regions constitute a key site of alcohol action on the NMDA receptor; 3) the precise kinetic mechanism by which alcohol interacts with these sites to alter NMDA receptor ion channel gating; and 4) whether effects of NMDA receptor mutations on gating kinetics and alcohol modulation observed in a non-neuronal cell line are also observed in CNS neurons. The results of these studies will yield important information about the molecular mechanism of alcohol modulation of the NMDA receptor, new insights into the structure and function of the NMDA receptor-ion channel, and a better understanding of the ways in which alcohols and similar molecules interact with proteins in general. Because NMDA receptors have vital and widespread roles in cognition, motor function, and memory, and contribute importantly to both the subjective effects of alcohol as well as its CNS depressant effects, the information gained in these studies will represent an important step forward in the understanding of alcohol effects on the nervous system.