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。快速突触 大脑中的传输是由化学物质直接激活的离子通道介导的 神经递质。NMDA和AMPA受体是谷氨酸门控离子通道，可以将 突触前释放谷氨酸，大脑中主要的兴奋性神经递质，进入 突触后信号。通过明确NMDA和AMPA受体的运作，我们将获得更好的 了解它们是如何控制大脑功能的。我们还将学习如何调节它们的功能 具有更高的精确度和特异度，以帮助理解和潜在地治疗脑部疾病，如 精神分裂症、癫痫以及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细胞的跨膜片段，M4片段，它是 位于孔域周围。我们实验室最近公布的初步数据表明 M4节段以新的方式调节NMDA和AMPA的核心突触功能 感受器。突出其重要性的是，M4节段的遗传和从头突变 导致神经发育障碍和癫痫脑病。《目标1》将讲述这部小说 假设突触上NMDA受体的独特动力学是由于两个动力学上不同的 M4片段以特定于亚单位的方式调节这些门。我们将解决 这一假设使用了半胱氨酸交联、严格的单通道分析和分子动力学 模拟。目标2将解决这一假设，即NMDA受体的M4片段是主要的 将外部结构域连接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分离来测试这一假设 使用电生理和基于FRET的测量来测试这种解耦。Aim 3将针对 假设AMPA受体中的M4片段具有不同的功能作用，包括 作为在突触中发现的辅助蛋白质的管道。在这里，我们将比较函数 NMDA和AMPA受体M4节段电生理特性的研究 录音和分子动力学模拟。我们的实验将描绘出分子特征 参与突触功能的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.