Role of cGKII in AMPA Receptor Transport

描述（由申请人提供）：AMPA受体产生触发动作电位形成的主要去极化电流。受体在突触处的插入和移除速率的改变可以改变受体突触丰度并控制突触强度。AMPA受体C-末端结构域磷酸化被认为是受体与控制运输的蛋白质相互作用的主要调节剂。突触将与突触活动相关的离子流转化为控制激酶和CTD磷酸化的生化信号。丝氨酸845上的GluR 1亚基（位于GluR 1 CTD的中间附近）通过PKA的磷酸化与质膜中突触外位点的GluR 1水平相关。我们将使用分子和电生理学的方法来研究丝氨酸845磷酸化的新机制的环GMP调节激酶cGKII。通过NMDAR激活nNOS，cGKII受NMDA受体控制，导致产生一氧化氮、激活可溶性鸟苷酸环化酶和产生cGMP，cGMP诱导cGKII。该项目的目标是：目标1。分析cGKII豆蔻酰化、二聚化和活化在GluR 1转运和生理中的作用。我们将分析cGKII的结构如何有助于GluR 1调节。目标2.明确S845磷酸化增加质膜GluR 1水平的机制。我们将确定cGKII磷酸化GluR 1并对GuR 1运输产生影响的细胞内位置。我们将试图区分是否cGKII调节GluR 1胞吐或如果GluR 1组成型交付是稳定的质膜上的S845磷酸化。我们将分离出响应S845磷酸化和控制GluR 1表面水平的因子。目标3。研究cGKII对GluR 4和GluR 2L转运的调控作用。GluR 4和GluR 2L是AMPAR亚基，它们在结构上与GluR 1相关，表明它们也可能受cGKII控制。我们将分析cGKII在这些亚基运输中的作用，以确定是否更普遍地采用NMDAR-nNOS-cGKII途径。该项目将提供有关突触功能的活动依赖性控制机制的新信息，并可能有助于确定一氧化氮在这些机制中的作用。公共卫生相关性：学习和记忆取决于大脑神经元之间连接强度的变化。该项目将研究一种新的途径，可以让神经元对自己的活动做出反应，并改变它们的连接强度。这项工作与记忆形成的机制和学习障碍的起源有关。它可以为设计新的药物以帮助维持记忆或减轻学习障碍提供基础。

DESCRIPTION (provided by applicant): AMPA receptors generate the major depolarizing currents that trigger the formation of action potentials. Alterations of the rates of insertion and removal of receptors at synapses can modify receptor synaptic abundance and control synaptic strength. AMPA receptor C-terminal domain phosphorylation is thought to be a major regulator of receptor interaction with proteins that control trafficking. Synapses convert ionic fluxes associated with synapse activity into biochemical signals that control kinases and CTD phosphorylation. Phosphorylation of the GluR1 subunit on serine 845, which lies near the middle of the GluR1 CTD, by PKA has been correlated with the level of GluR1 at extrasynaptic sites in the plasma membrane. We will use molecular and electrophysiological approaches to investigate a new mechanism of serine 845 phosphorylation by the cyclic GMP regulated kinase cGKII. cGKII is under the control of the NMDA receptor through NMDAR activation of nNOS, leading to the production of nitric oxide, activation of soluble guanylate cyclase and production of cGMP, which induces cGKII. The Aims of this project are: Aim 1. To analyze the roles of cGKII myristoylation, dimerization and activation in GluR1 trafficking and physiology. We will analyze how the structure of cGKII contributes to GluR1 regulation. Aim 2. To distinguish the mechanism of S845 phosphorylation in increasing GluR1 levels on the plasma membrane. We will determine the place within the cell that cGKII phosphorylates GluR1 and exerts its effect on GuR1 trafficking. We will attempt to distinguish whether cGKII regulates GluR1 exocytosis or if GluR1 delivered constitutively is stabilized on the plasma membrane by S845 phosphorylation. We will isolate factors that respond to S845 phosphorylation and control GluR1 surface levels. Aim 3. To study the cGKII regulated trafficking of GluR4 and GluR2L. GluR4 and GluR2L are AMPAR subunits that are structurally related to GluR1 in ways that suggest that they may also be controlled by cGKII. We will analyze the role of cGKII in the trafficking of these subunits to determine if the NMDAR-nNOS-cGKII pathway is more generally employed. This project will provide new information about mechanisms of activity dependent control of synapse function and may help to define the role of nitric oxide in these mechanisms. PUBLIC HEALTH RELEVANCE: Learning and memory depend upon changes in the strength of connections between neurons in the brain. This project will study a new pathway that can allow neurons to respond to their own activity and change the strength of their connections. This work is relevant to mechanisms of memory formation and to the origin of learning disabilities. It can provide the basis for devising new drugs to help maintain memory or lessen learning disabilities.