Physiology and pharmacology of GluN3-containing NMDA receptors

项目摘要/摘要 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(CNS)。已克隆了7个NMDA受体亚基(GluN1、GluN2A-D和 GluN3A-B)组装成四聚体受体。中枢神经系统中的大多数NMDA受体由两个 GluN1和两个GluN2亚基，这两个亚基被深入研究并被很好地理解。相比之下，许多人 含有GluN3的NMDA受体的特性仍未解决。近年来，含有GluN3的NMDA 受体与突触成熟和突触可塑性有关，并与几个中枢神经系统有关 精神错乱。含有GluN3受体的选择性配体缺失，从而阻碍了对它们的研究 在神经元信号传递中的作用。神经元型GluN3受体的结构和功能较差 明白了。长期接触甘氨酸的生理条件会导致GluN3- 含有处于强烈不敏感状态的受体。该项目的总体目标是缓解这些问题 两种含GluN3的NMDA受体对神经元信号转导的障碍和指导 GluN1和两个GluN3A亚基。在目标1中，我们将研究天然GluN3A-的离子通道性质。 含有受体的。新近发现的天然GluN1/3A的功能和药理性质 受体是未知的。我们将使用电生理记录来研究功能和药理学。 脑片中天然GluN1/3A受体和HEK细胞中表达的重组GluN1/3A受体。这 AIM还将研究与生理相关的条件，这些条件可以激活来自 天然的GluN1/3A受体。在目标2中，我们开发了含有GluN3A的NMDA的分子药理学 感受器。神经元型GluN1/3A受体的发现加强了GluN3A- 选择性配体。我们将在GluN1/3A受体上评估新的正构配体和变构调节剂 以开发更有效和更具选择性的GluN3配体。这个目标的目标是提供先导化合物 和构效关系，可以指导新的GluN3选择性药理的开发 工具。在目标3中，我们将定义包含神经元GluN3A的生理作用的结构决定因素 感受器。神经元GluN3A表达阻止突触成熟，GluN3A缺陷小鼠神经元 与野生型小鼠相比，表现为树突棘密度增加。我们将确定结构(例如 受体结构域)和功能特性(例如，激动剂结合) 调节脊柱密度的变化，并评估GluN3A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.