AMPA receptor trafficking at cerebellar parallel fiber-stellate cell synapses

描述（由申请人提供）：AMPA受体的活动依赖性动员和突触靶向是突触可塑性表达的重要步骤，被认为是大脑学习和记忆的细胞关联。小脑皮层的平行纤维-星状细胞（PF-SC）突触是运动控制和协调所必需的结构，它表现出一种独特的突触可塑性形式，其特征是钙渗透性ampar被钙不渗透性ampar以活动依赖的方式取代。这两种受体可以通过简单的生物物理分析相互区分，使其成为探测突触可塑性过程中亚单位特异性AMPAR靶向的分子基础的理想模型系统。进一步了解可渗透钙的ampar转运的分子机制与人类疾病直接相关。钙渗透性ampar的调控涉及广泛的疾病机制，包括中风期间的缺血性损伤和癫痫、肌萎缩侧索硬化症（ALS）和神经性疼痛引起的兴奋性损伤。在本提案中，我将验证我的假设，即在PF-SC突触可塑性期间，AMPAR的亚单位特异性运输需要AMPAR辅助亚单位stargazin。该提案分为两个具体目标。在Specific Aim 1中，我将对stargazer突变小鼠进行电生理记录，以系统地描述stargazin在调节AMPAR表面表达、突触中的作用

DESCRIPTION (provided by applicant): The activity-dependent mobilization and synaptic targeting of AMPA receptors is an essential step in the expression of synaptic plasticity, regarded as the cellular correlate of learning and memory in the brain. The parallel-fiber-stellate cell (PF-SC) synapse of the cerebellar cortex, a structure essential for motor-control and coordination, exhibits a unique form of synaptic plasticity characterized by the activity-dependent replacement of calcium-permeable AMPARs by calcium-impermeable AMPARs. These two pools of receptors can be distinguished from one another by a simple biophysical assay making it an ideal model system for probing the molecular basis for subunit-specific AMPAR targeting during synaptic plasticity. Furthering our understanding of the molecular mechanisms underlying the trafficking of calciumpermeable AMPARs is immediately relevant to human disease. The regulation of calcium-permeable AMPARs is implicated in a wide range of disease mechanisms including ischemic damage during stroke and excitotoxic damage resulting from epilepsy, amyotrophic lateral sclerosis (ALS) and neuropathic pain. In this proposal, I will test my hypothesis that stargazin, an AMPAR auxiliary subunit is required for subunitspecific trafficking of AMPARs during plasticity at PF-SC synapses. The proposal is divided into two Specific Aims. In Specific Aim 1, 1 will carry out electrophysiological recordings from stargazer mutant mice in order to systematically delineate the role of stargazin in regulating AMPAR surface expression, synaptic targeting and plasticity at cerebellar PF-SC synapses. In Specific Aim 2, 1 will examine the molecular basis for subunit-specific AMPAR trafficking at PF-SC synapses. To this end, I will carry out viral-mediated in vivo gene transfer in stargazer mice as a way of reintroducing both a full-length and a deletion mutant version of stargazin into stellate cells. Such experiments will allow me to zero in on the precise role that stargazing plays in mediating changes in AMPAR subunit composition during plasticity. This would be the first demonstration of subunit specificity in stargazin-mediated targeting during synaptic plasticity. PUBLIC HEALTH RELEVANCE: An essential feature of synaptic plasticity, the mechanism through which neurons in the brain store information, is the exquisite control of a synapse's supply of AMPA receptors. This proposal is directed towards understanding the molecular machinery responsible for AMPA receptor regulation at synapses. In so doing, I hope to provide important insights into pathological states of the brain including stroke, epilepsy, Lou Gehrig's Disease and chronic pain.