Mechanism for Regulating Kainate-Type Glutamate Receptor Activity

描述(由申请人提供)：这项建议的广泛目标是了解大脑中兴奋性突触传递的调节机制。神经疾病，包括智力低下、自闭症、癫痫和共济失调，都是由大脑中神经回路的中断引起的。神经回路由通过神经递质在突触处相互通信的神经元组成。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，即AMPA受体、NMDA受体和海人酸型受体。AMPA受体介导突触的快速传递，而NMDA受体调节突触的可塑性。然而，红藻氨酸受体的生理作用仍不清楚。我们最近利用无偏见的蛋白质组筛选，鉴定出一种新的跨膜蛋白，Neto2，它与红藻氨酸受体相互作用。在异种细胞和神经元中，Neto2调节红藻氨酸受体的通道特性，而红藻氨酸受体反过来又调节Neto2的运输。然而，有几个问题尚未解答，以揭示红藻氨酸受体在大脑中的作用。1.Neto2/海人藻酸受体复合体是如何组装和运输到细胞表面的？2.Neto2和海人藻酸受体是如何相互调节的？3.Neto2/海人藻酸受体复合体如何介导突触传递？在这项提案中，我们将解决这些问题，以揭示红藻氨酸受体/Neto2复合体在大脑中的功能作用。我们将利用不同的转基因小鼠模型来确定红藻氨酸受体/Neto2复合体的蛋白质组装顺序和表面转运机制。我们还将以非洲爪哇的卵母细胞为模型系统，研究Neto2和海人藻酸受体的结构和功能。此外，我们将通过电生理实验重建海人藻酸受体介导的突触传递，以揭示海人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中突触传递的机制提供基本的见解，涉及大脑中神经回路的作用。由于海人藻酸受体在包括自闭症、精神分裂症、癫痫和感觉转导改变在内的几种神经系统疾病中的潜在作用已被提出，这项工作将为药物发现寻找新的靶点。

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.