Physiology and pharmacology of GluN3-containing NMDA receptors

项目总结/摘要 NMDA型谷氨酸受体是配体门控离子通道，介导兴奋性神经传递， 中枢神经系统（CNS）。已经克隆了七种NMDA受体亚基（GluN 1、GluN 2A-D和GluN 2A-D）。 GluN 3A-B）组装成四聚体受体。CNS中的大多数NMDA受体由两个 GluN 1和两个GluN 2亚基，这是深入研究和充分理解。相比之下，许多 含有GluN 3的NMDA受体的性质仍然没有得到解决。近年来，含GluN 3的NMDA 受体与突触成熟和突触可塑性有关，并与几种中枢神经系统有关。 紊乱缺少含GluN 3受体的选择性配体，从而阻碍了对它们的研究。 在神经元信号传导中的作用。神经元含GluN 3受体的结构和功能较差， 明白长期暴露于甘氨酸的生理条件导致GluN 3- 含有处于强烈脱敏状态的受体。该项目的总体目标是减轻这些 屏障和指导未来的研究神经元信号的GluN 3含有NMDA受体组成的两个 GluN 1和两个GluN 3A亚基。在目的1中，我们将研究天然GluN 3A-的离子通道特性。 含有受体。新发现的天然GluN 1/3A的功能和药理学性质 受体未知。我们将使用电生理记录来研究功能和药理学 脑切片中的天然GluN 1/3A受体和HEK细胞中表达的重组GluN 1/3A受体。这 aim还将研究生理相关条件，这些条件可以激活电流反应， 天然GluN 1/3A受体。目的2：研究含GluN 3A的NMDA的分子药理学 受体。神经元GluN 1/3A受体的发现加强了开发GluN 3A-受体的理论基础。 选择性配体我们将评估GluN 1/3A受体的新型正构配体和变构调节剂， 为了开发更有效和选择性的GluN 3配体。该目标的目标是提供先导化合物 和构效关系，可以指导新的GluN 3选择性药理学的发展， 工具.在目标3中，我们将定义神经元GluN 3A的生理作用的结构决定因素， 受体。神经元GluN 3A表达阻止突触成熟和GluN 3A缺陷小鼠中的神经元 与野生型小鼠相比显示出增加的树突棘密度。我们将识别结构（例如， 受体结构域）和含有GluN 3A的NMDA受体的功能特征（例如激动剂结合）， 介导树突棘密度的变化，并评估GluN 3A选择性配体对树突棘密度的影响。

PROJECT SUMMARY/ABSTRACT NMDA-type glutamate receptors are ligand-gated ion channels that mediate excitatory neurotransmission in the central nervous system (CNS). Seven NMDA receptor subunits have been cloned (GluN1, GluN2A-D, and GluN3A-B) that assemble into tetrameric receptors. Most NMDA receptors in the CNS are composed of two GluN1 and two GluN2 subunits, which are intensely investigated and well understood. By contrast, many properties of GluN3-containing NMDA receptors remain unresolved. In recent years, GluN3-containing NMDA receptors have been implicated in synapse maturation and synaptic plasticity, and linked to several CNS disorders. Selective ligands for GluN3-containing receptors are missing, thereby hampering studies of their roles in neuronal signaling. Structure and function of neuronal GluN3-containing receptors are poorly understood. Physiological conditions of prolonged exposure to glycine result in accumulation of GluN3- containing receptors in a strongly desensitized state. The overarching goal of this project is to mitigate these barriers and guide future studies on neuronal signaling by GluN3-containing NMDA receptors composed of two GluN1 and two GluN3A subunits. In Aim 1, we will investigate ion channel properties of native GluN3A- containing receptors. Functional and pharmacological properties of the recently discovered native GluN1/3A receptors are unknown. We will use electrophysiological recordings to investigate function and pharmacology of native GluN1/3A receptors in brain slices and recombinant GluN1/3A receptors expressed in HEK cells. This aim will also investigate physiologically relevant conditions that can enable activation of current responses from native GluN1/3A receptors. In Aim 2, we develop the molecular pharmacology of GluN3A-containing NMDA receptors. The discovery of neuronal GluN1/3A receptors strengthens the rationale to develop GluN3A- selective ligands. We will evaluate novel orthosteric ligands and allosteric modulators at GluN1/3A receptors in order to develop more potent and selective GluN3 ligands. The goal of this aim is to provide lead compounds and structure-activity relationships that can guide the development of novel GluN3-selective pharmacological tools. In Aim 3, we will define structural determinants of physiological roles for neuronal GluN3A-containing receptors. Neuronal GluN3A expression prevents synapse maturation, and neurons in GluN3A-deficient mice display increased dendritic spine density compared to wild type mice. We will identify the structural (e.g. receptor domains) and functional features (e.g. agonist binding) of GluN3A-containing NMDA receptors that mediate changes in spine density and evaluate effects of GluN3A-selective ligands on dendritic spine density.