Gating and permeation in ionotropic glutamate receptors

我们的长期目标是解决大脑疾病的分子决定因素。快突触 在大脑中的传输是由离子通道介导的，离子通道由化学物质直接激活。 神经传递素NMDA和AMPA受体是谷氨酸门控的离子通道，其将NMDA受体和AMPA受体转化为谷氨酸受体。 突触前释放谷氨酸，大脑中主要的兴奋性神经递质，进入一个 突触后信号通过明确NMDA和AMPA受体的作用机制，我们将更好地了解NMDA和AMPA受体的作用机制， 了解它们如何控制大脑功能。我们还将学习如何调节它们的功能 以更高的精确度和特异性来帮助理解并潜在地治疗大脑紊乱， 精神分裂症、癫痫和与急性和慢性脑部疾病相关的兴奋性毒性。 我们的实验将集中在真核生物的跨膜片段，M4片段，这是 位于孔域周围。我们实验室最近发表的初步数据表明， M4节段以新的方式调节NMDA和AMPA的核心突触功能 受体。突出它们的重要性的是，M4节段中的遗传和新生突变 诱发神经发育障碍和癫痫性脑病。目标1将解决小说 假设NMDA受体在突触上的独特动力学是由于两种动力学不同的 门和M4段调节这些门在一个亚单位特定的方式。我们将解决 这一假设使用半胱氨酸交联，严格的单通道分析，和分子动力学 仿真。目的2将阐明NMDA受体中的M4片段是NMDA受体的主要功能的假设。 将外部结构域偶联到跨膜和内部结构域的变构管道。在这里，我们将 通过将外部结构域与跨膜结构域和内部结构域解偶联来检验该假设， 使用电生理学和基于FRET的测量来测定这种去偶联。目标3将解决 假设AMPA受体中的M4片段执行不同的功能作用，包括 作为突触中辅助蛋白的通道。在这里，我们将比较功能 NMDA和AMPA受体M4片段之间的电生理特性 记录和分子动力学模拟。我们的实验将描绘出 促进突触功能的NMDA和AMPA受体。这些信息将有助于 开发针对神经系统疾病中这些受体的特定疗法。

Our long-term goal is to address molecular determinants of brain disorders. Fast synaptic transmission in the brain is mediated by ion channels that are directly activated by a chemical neurotransmitter. NMDA and AMPA receptors are glutamate-gated ion channels that convert the presynaptic release of glutamate, the predominant excitatory neurotransmitter in the brain, into a postsynaptic signal. By defining the operation of NMDA and AMPA receptors, we will gain a better understanding of how they control brain function. We will also learn how to modulate their function with greater precision and specificity to help understand, and potentially treat, brain disroders such as schizophrenia, epilepsy, and the excitotoxicity associated with acute and chronic brain disorders. Our experiments will focus on a eukaryotic transmembrane segment, the M4 segment, which is positioned around the pore domain. Recent published and preliminary data from our lab has indicated that the M4 segments act in novel ways to regulate core synaptic functions of NMDA and AMPA receptors. Highlighting their significance is that inherited and de novo mutations in the M4 segments induce neurodevelopmental disorders and epileptic encephalopathies. Aim 1 will address the novel hypothesis that the unique kinetics of NMDA receptors at synapses are due to two kinetically distinct gates and that the M4 segments regulate these gates in a subunit-specific manner. We will address this hypothesis using cysteine cross-linking, rigorous single channel analysis, and molecular dynamic simulations. Aim 2 will address the hypothesis that the M4 segments in NMDA receptors are a major allosteric conduit coupling external domains to transmembrane and internal domains. Here, we will test this hypothesis by decoupling external domains from transmembrane and internal domains and assay this decoupling using electrophysiological and FRET based measurements. Aim 3 will address the hypothesis that the M4 segments in AMPA receptors carry out distinct functional roles including acting as a conduit for auxiliary proteins found at synapses. Here, we will compare functional properties between the M4 segments in NMDA and AMPA receptors using electrophysiological recordings and molecular dynamic simulations. Our experiments will delineate molecular features of NMDA and AMPA receptors that contribute to synaptic function. This information will aid in developing specific therapies to target these receptors in nervous system disorders.