The Regulation of GABAA Receptor Cell Surface Stability

描述（申请人提供）：GABA （γ -氨基丁酸）是哺乳动物神经系统中主要的抑制性神经递质。GABA的快速突触抑制作用主要是由于GABAA受体的激活，GABAA受体是Cl-渗透性配体门控离子通道。这些受体也是几种临床重要药物的靶点，包括苯二氮卓类药物、巴比妥类药物、神经类固醇和全身麻醉剂。此外，GABAA受体功能的改变在许多中枢神经系统病理中至关重要，包括：癫痫、焦虑、成瘾、自闭症和智力低下。虽然GABAA受体功能的药理调控在临床上已被广泛利用，但神经元控制这些蛋白功能和细胞表面稳定性的内源性机制仍不清楚。然而，考虑到GABAA受体作为突触抑制、药物靶点和人类疾病的介质所起的作用，这个问题至关重要。我们假设GABAA受体的细胞表面稳定性是通过与AP2复合物的直接相互作用来调节的，AP2复合物在将货物招募到网格蛋白包被的凹坑中以促进内吞作用中起着至关重要的作用。这些相互作用反过来依赖于GABAA受体的磷酸化状态，这受到定义的细胞信号通路的动态调节。因此，我们将结合细胞生物学、生物化学和电生理学的方法来实现三个独立但相关的具体目标：

DESCRIPTION (provided by applicant): GABA (gamma-aminobutyric acid) is the major inhibitory neurotransmitter in the mammalian nervous system. The fast synaptic inhibitory action of GABA is due largely to the activation of GABAA receptors, which are Cl- permeable ligand-gated ion channels. These receptors are also targets for several clinically important drug classes, including benzodiazepines, barbiturates, neurosteroids and general anesthetic. Moreover, modifications of GABAA receptor function are critical in a number of CNS pathologies including: epilepsy, anxiety, addiction, autism, and mental retardation. While the pharmacological manipulation of GABAA receptor function has been widely exploited clinically the endogenous mechanisms used by neurons to control the function and cell surface stability of these proteins remain unknown. However this issue is of central importance given the roles GABAA receptors play as mediators of synaptic inhibition, drug targets and in human disease. We hypothesize that the cell surface stability of GABAA receptors, is regulated via direct interactions with the AP2 complex, which plays an essential role in the recruitment of cargo into clathrin-coated pits to facilitate endocytosis. These interactions are dependent in turn on the phosphorylation status of GABAA receptors, which is subject to dynamic regulation by defined cell signaling pathways. Thus we will use a combination of cell biological, biochemical and electrophysiological approaches to carry out three independent but related specific aims: Specific Aim 1. To test the hypothesis that specific motifs mediate the interaction of GABAA receptors with the AP2 complex, and that these interactions are regulated by receptor phosphorylation. Specific Aim 2. To test the hypothesis that PKC activity regulates the phosphorylation, cell surface stability and activity of GABAA receptors. Specific Aim 3. To examine the significance of AP2 mediated endocytosis in the control of GABAA receptor cell surface stability. Together, our approaches will provide a more thorough understanding of the cell surface stability and function of GABAA receptors. The results of these studies will have the potential to make significant contributions to the development of novel therapeutic strategies for such debilitating disorders as epilepsy, anxiety, addiction, autism, and mental retardation.