Subproject Investigator: Kasper B. Hansen

NMDA型谷氨酸受体是介导兴奋性神经传递的配体门控离子通道。 中枢神经系统，但也牵涉到许多神经和精神疾病。NMDA 受体由甘氨酸结合的GluN1亚基和谷氨酸结合的GluN2亚基组成。一 GluN1亚基已被克隆，有四种类型的GluN1亚基(GluN2A-D)具有不同的 赋予NMDA受体不同功能特性的发育和区域表达水平。 GluN1甘氨酸位点激动剂在严重抑郁障碍中表现出快速起效的症状缓解，并减少 通过抑制全部内源性激动剂(如甘氨酸)的活性而保持相当大的NMDA受体活性 承诺开发新的抗抑郁药物。此外，最近的研究表明，多达 所有难治性儿童癫痫障碍患者中有20%可能是遗传或新生的 编码GluN2ANMDA受体亚单位的基因突变。新的部分GluN1激动剂 已经设计了GluN2亚基之间的选择性，并已经设计了一种独特的作用机制 发现了一类降低甘氨酸亲和力的GluN2A选择性负变构调节剂(NAMS) 与GluN1结合。使用X射线结晶学、定点突变和电生理记录 关于NMDA受体的功能，本项目的目标1将研究GluN2A选择性NAMS的结合部位和 目标2将定义新类别的部分激动剂在GluN1甘氨酸结合位点的结合接触。目标3 我将更详细地研究NAM和甘氨酸结合位点之间的变构相互作用 诱变和工程化的二硫键。GluN2A-对变构抑制作用的关系 选择性NAMS和GluN1激动剂的疗效也将被揭示。这两个目标的组合将发现新的 NMDA受体的区域，可用于亚单位选择性配体的工程，并提供 机械和结构洞察力，使合理设计新的、临床相关的调节器，从而减少 GluN1甘氨酸位点活性。

NMDA-type glutamate receptors are ligand-gated ion channels that mediate excitatory neurotransmission in the central nervous system, but are also implicated in many neurological and psychiatric disorders. NMDA receptors are composed of both glycine-binding GluN1 subunits and glutamate-binding GluN2 subunits. One GluN1 subunit has been cloned and there are four types of GluN2 subunits (GluN2A-D) with different developmental and regional expression levels that endow NMDA receptors with different functional properties. GluN1 glycine site agonists show rapid onset symptomatic relief in major depressive disorder, and reduction of NMDA receptor activity by inhibiting the activity of full endogenous agonists (e.g. glycine) hold considerable promise for the development of new antidepressant drugs. In addition, recent studies have shown that up to 20% of all patients with treatment-resistant childhood epilepsy disorders may have inherited or de novo mutations in the gene encoding the GluN2A NMDA receptor subunit. New partial GluN1 agonists with selectivity between GluN2 subunits have been designed, and a unique mechanism of action have been uncovered for a class of GluN2A-selective negative allosteric modulators (NAMs) that reduce affinity of glycine binding to GluN1. Using X-ray crystallography, site-directed mutagenesis, and electrophysiological recordings of NMDA receptor function, Aim 1 of this project will investigate the binding site of GluN2A-selective NAMs and Aim 2 will define binding contacts for new classes of partial agonists at the GluN1 glycine binding site. Aim 3 will examine the allosteric interaction between NAM and glycine binding sites in more detail using site-directed mutagenesis and engineered disulfide bonds. The relationship between allosteric inhibition by GluN2A- selective NAMs and GluN1 agonist efficacy will also be uncovered. This combination of aims will uncover new regions of NMDA receptors that can be exploited for engineering of subunit-selective ligands, and provide mechanistic and structural insight to enable rational design of novel, clinically-relevant modulators that reduce GluN1 glycine site activity.