Regulation of NMDAR-Mediated Synaptic Signaling

项目概要/摘要 我们拟研究离子型谷氨酸受体（iGluRs）的NMDA亚型（NMDARs）及其与谷氨酸受体（iGluRs）的相互作用。 NRAP-1是第一个被鉴定的NMDAR特异性辅助蛋白，我们最近在一项研究中发现了它。 在C.优雅NMDAR在进化上 保守的并且众所周知它们在突触可塑性中的作用，即，长时程增强（LTP）;其重要性 学习和记忆的细胞模型;以及它们直接或间接参与许多神经和 精神疾病虽然NRAP-1修饰突触后NMDAR的功能，但我们发现它是一种神经递质。 由突触前神经元释放这一发现为我们的研究提供了一个重大的概念性进展。 理解NMDAR介导的突触信号的调节，以及对神经元的控制和神经元的功能的影响。 突触强度和涉及NMDAR的某些临床病症。在初步实验中，我们 成功地获得了重组产生的NRAP-1的晶体，并在1.9 °处确定了晶体结构 高分辨率。阐明NRAP-1的结构为NRAP-1如何 修改NMDAR功能。通过对脊椎动物和C.线虫NMDAR，我们也证明了一个 NMDAR氨基末端结构域（ATD）在受体门控和 NRAP-1的作用机制。我们现在计划在这项基础性工作的基础上， 调节NMDAR功能，即，NRAP-1和NMDAR之间的相互作用是什么， 这些相互作用如何改变受体动力学？与NMDAR的过度表达相反，我们发现 体内NRAP-1的过表达显著增加了NMDAR介导的电流和行为。这 对控制突触可塑性有重要意义。此外，我们发现NRAP-1是积极的 沿着沿着神经过程传输。总之，这些发现表明调节NRAP-1分泌可能 是一种用于调节突触强度的活动依赖性变化的机制。因此，我们将解决 NRAP-1的运输和分泌的分子要求。我们提出的研究的相关性 是高的，因为NMDAR介导的信号传导障碍与突触病变有关， 神经退行性疾病以及精神健康疾病如精神分裂症和抑郁症。 突触分子在进化上是保守的，我们对调节突触的机制的理解 突触信号传导极大地受益于在无脊椎动物如果蝇和 C.优雅值得注意的是，NMDAR和NRAP-1样蛋白似乎共同进化，表明脊椎动物 NMDAR可能受辅助蛋白调节。因此，我们预期我们计划进行的研究， 为以蛋白质-蛋白质为中心的NMDAR的新机制理解提供了框架 交互.

PROJECT SUMMARY/ABSTRACT We propose to study the NMDA-subtype (NMDARs) of ionotropic glutamate receptors (iGluRs) and their regulation by NRAP-1, the first identified NMDAR-specific auxiliary protein, which we recently discovered in a genetic screen for modifiers of NMDAR-mediated behavior in C. elegans. NMDARs are evolutionarily conserved and well known for their role in synaptic plasticity, i.e., long-term potentiation (LTP); their importance for cellular models of learning and memory; and their direct or indirect involvement in many neurological and psychiatric disorders. Although NRAP-1 modifies the function of postsynaptic NMDARs, we showed that it was released by presynaptic glutamatergic neurons. This discovery provided a major conceptual advance in our understanding of the regulation of NMDAR-mediated synaptic signaling, with implications for both the control of synaptic strength and for certain clinical disorders involving NMDARs. In preliminary experiments, we successfully obtained crystals of recombinantly produced NRAP-1 and determined the crystal structure at 1.9 Å resolution. Elucidating the structure of NRAP-1 has provided important new insight into how NRAP-1 modifies NMDAR function. By studying vertebrate and C. elegans NMDARs, we have also demonstrated a fundamental importance for the NMDAR amino-terminal domain (ATD) with respect to both receptor gating and to the mechanism of action of NRAP-1. We now plan to build on this foundational work and ask how NRAP-1 functions to modulate NMDAR function, i.e., what are the interactions between NRAP-1 and NMDARs, and how do these interactions change receptor kinetics? In contrast to overexpression of NMDARs, we discovered that overexpression of NRAP-1 in vivo significantly increased NMDAR-mediated currents and behavior. This has important implications for the control of synaptic plasticity. Furthermore, we found that NRAP-1 is actively transported along neural processes. Together, these findings suggest that modulating NRAP-1 secretion might be a mechanism used to regulate activity dependent changes in synaptic strength. Therefore, we will address the molecular requirements for the transport and secretion of NRAP-1. The relevance of our proposed studies is high because disorders of NMDAR-mediated signaling are implicated in synaptopathies associated with neurodegenerative disorders as well as for mental health illnesses such as schizophrenia and depression. Synaptic molecules are evolutionarily conserved, and our understanding of the mechanisms that regulate synaptic signaling has greatly benefited from genetics-based studies in invertebrates such as Drosophila and C. elegans. Notably, NMDARs and NRAP-1-like proteins appear to have co-evolved suggesting that vertebrate NMDARs are likely regulated by auxiliary proteins. We therefore anticipate that our planned studies will help provide a framework for a new mechanistic understanding of NMDARs centered on protein-protein interactions.