Mechanism for Regulating Kainate-Type Glutamate Receptor Activity

描述（由申请人提供）：该提案的总体目标是了解调节大脑兴奋性突触传递的机制。神经系统疾病，包括智力低下、自闭症、癫痫和共济失调，是由大脑神经回路破坏引起的。神经回路由神经元组成，这些神经元通过神经递质在突触处相互通信。大脑中最丰富的兴奋性神经递质是谷氨酸。谷氨酸作用于三类离子型谷氨酸受体：AMPA、NMDA 和红藻氨酸型受体。 AMPA 受体介导快速突触传递，而 NMDA 受体则调节突触可塑性。然而，红藻氨酸受体的生理作用仍不清楚。我们最近使用无偏蛋白质组学筛选鉴定了一种新型跨膜蛋白 NETO2，它与红藻氨酸受体相互作用。在异源细胞和神经元中，NETO2 调节红藻氨酸受体的通道特性，而红藻氨酸受体反过来调节 NETO2 的运输。然而，还有几个悬而未决的问题来揭示红藻氨酸受体在大脑中的作用。 1. NETO2/红藻氨酸受体复合物如何组装并运输至细胞表面 2. NETO2 和红藻氨酸受体如何相互调节？ 3. NETO2/红藻氨酸受体复合物如何介导突触传递？在本提案中，我们将解决这些问题，以揭示红藻氨酸受体/NETO2 复合物在大脑中的功能作用。我们将使用各种转基因小鼠模型来确定红藻氨酸受体/NETO2 复合物的蛋白质组装顺序和表面运输机制。我们还将使用非洲爪蟾卵母细胞作为模型系统来检查 NETO2 和红藻氨酸受体的结构和功能分析。此外，我们将重建神经元中红藻氨酸受体介导的突触传递，通过电生理实验揭示红藻氨酸受体在兴奋性突触传递中的作用。这些研究将为调节兴奋性突触突触传递与大脑神经回路的作用的机制提供基本见解。由于红藻氨酸受体在多种神经系统疾病（包括自闭症、精神分裂症、癫痫和感觉转导改变）中的潜在作用已被提出，这项工作将确定药物发现的新靶点。

DESCRIPTION (provided by applicant): The broad goal of this proposal is to understand mechanisms for regulating excitatory synaptic transmission in the brain. Neurological diseases, including mental retardation, autism, epilepsy, and ataxia, are caused by the disruption of neural circuits in the brain. Neural circuits consist of neurons that communicate with each other at synapses through neurotransmitters. The most abundant excitatory neurotransmitter in the brain is glutamate. Glutamate acts on three classes of ionotropic glutamate receptors, AMPA-, NMDA- and kainate-type receptors. AMPA receptors mediate fast synaptic transmission, whereas NMDA receptors modulate synaptic plasticity. However, the physiological roles of kainate receptors remain unclear. We have recently identified a novel transmembrane protein, NETO2 that interacts with the kainate receptor, using an unbiased proteomic screen. In heterologous cells and neurons, NETO2 modulates the channel properties of kainate receptors, and kainate receptors, in turn, modulate NETO2 trafficking. However, there are several unanswered questions to reveal roles of kainate receptors in the brain. 1. How does NETO2/kainate receptor complex assemble and traffic to the cell surface 2. How do NETO2 and kainate receptors modulate each other? 3. How does NETO2/kainate receptor complex mediate the synaptic transmission? In this proposal, we will address these questions to reveal functional roles of kainate receptor/NETO2 complex in the brain. We will identify protein assembling order of kainate receptor/NETO2 complex and mechanisms for surface trafficking using various transgenic mouse model. We will also examine structure and functional analysis of NETO2 and kainate receptors using Xenopus laevis oocyte as a model system. Furthermore, we will reconstitute kainate receptor mediated synaptic transmission in neurons to reveal roles of kainate receptors in excitatory synaptic transmission with electrophysiological experiments. These studies will provide fundamental insights into the mechanisms that regulate synaptic transmission at excitatory synapses regards to roles of neural circuits in the brain. Because potential roles of kainate receptors in several neurological diseases including autism, schizophrenia, epilepsy and altered sensory transduction have been proposed, this work will identify novel targets for drug discovery.