Trafficking of a Neuronal Glutamate Transporter, EAAC1

神经元谷氨酸转运蛋白 EAAC1 的贩运

• 批准号: 7027708
• 负责人: Michael Byrne Robinson
• 金额: $ 33.74万
• 依托单位: CHILDREN'S HOSP OF PHILADELPHIA
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-05-15 至 2009-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7027708
• 关键词: biological signal transduction; caveolins; endocytosis; excitatory aminoacid; glutamate transporter; immunoprecipitation; intracellular transport; laboratory rat; long term potentiation; molecular cloning; neural plasticity; neurotransmitter transport; platelet derived growth factor; protein kinase C; protein localization; protein transport; tissue /cell culture; western blottings

DESCRIPTION (provided by applicant): Glutamate is the predominant rapid excitatory neurotransmitter in the mammalian CNS and is involved in several forms of plasticity in the developing and adult nervous system. Excessive activation of glutamate receptors contributes to brain damage observed in acute insults to the CNS, including ischemia and head trauma. The extracellular concentrations of glutamate are controlled by a family of sodium-dependent transporters. We and others have found that the activity of one of these transporters, called EAAC1, can be rapidly increased by either activation of protein kinase C (PKC) or the platelet-derived growth factor receptor. These affects are associated with a redistribution of EAAC1 from a subcellular compartment to the cell surface and are independent of synthesis of new transporters. Based on our preliminary studies, we would like to pursue the following four specific aims: 1) We propose to examine the signaling molecules that are required for the PDGF-dependent redistribution of EAAC1. 2) We have recently found that EAAC1 constitutively recycles between the plasma membrane and intracellular compartments with a half-life of approximately 5-7 min. We propose to determine if EAAC1 is internalized by a caveolin-dependent endocytosis pathway and begin to identify the subcellular compartments used for recycling of EAAC1. 3) We have found that EAAC1 forms complexes with protein interacting with C kinase (PICK1) and the alpha subtype of PKC. We propose to identify domains required for these interactions and to determine how these interactions affect EAAC1 trafficking. 4) The mechanisms that regulate EAAC1 trafficking and one of the glutamate receptors appear to be quite similar, and a signal that increases EAAC1 decreases GluR2. We propose to use a variety of approaches to determine if EAAC1 and ionotropic glutamate receptors are regulated in this apparently complementary fashion using other approaches to chemically induce either long term depression (LTD) or long term potentiation (LTP). We are intrigued by this regulation because EAAC1 is enriched in areas where synaptic transmission is highly plastic and in neurons that are exquisitely sensitive to excitotoxic insults. EAAC1 is localized on the post-synaptic membrane and is perisynaptic surrounding GluRs where it is ideally situated to fine-tune synaptic transmission. We suspect that understanding the regulation of EAAC1 could have implications for understanding glutamate toxicity and/or synaptic plasticity.

描述（由申请人提供）：谷氨酸是哺乳动物中枢神经系统中主要的快速兴奋性神经递质，并且在发育和成人神经系统中参与了几种形式的可塑性。谷氨酸受体的过度激活有助于在包括缺血和头部外伤在内的急性侮辱中观察到的脑损伤。谷氨酸的细胞外浓度由钠依赖性转运蛋白家族控制。我们和其他人发现，通过激活蛋白激酶C（PKC）或血小板衍生的生长因子受体，可以迅速增加这些称为EAAC1的转运蛋白的活性。这些影响与EAAC1从亚细胞隔室重新分布有关，并且与新转运蛋白的合成无关。根据我们的初步研究，我们想追求以下四个特定目的：1）我们建议检查EAAC1依赖PDGF依赖性重新分布所需的信号分子。 2）我们最近发现，EAAC1在质膜和细胞内室之间的组成型回收，半衰期约为5-7分钟。我们建议确定EAAC1是否通过小窝蛋白依赖性内吞途径内化，并开始识别用于回收EAAC1的亚细胞隔室。 3）我们发现，EAAC1与蛋白质与C激酶（PICC1）和PKC的α亚型相互作用形成复合物。我们建议确定这些相互作用所需的域，并确定这些相互作用如何影响EAAC1运输。 4）调节EAAC1运输和谷氨酸受体之一的机制似乎非常相似，并且增加了EAAC1的信号降低了Glur2。我们建议使用多种方法来确定EAAC1和离子型谷氨酸受体是通过这种显然互补的方式使用其他化学诱导长期抑郁症（LTD）还是长期增强（LTP）来调节的。我们对这种调节很感兴趣，因为EAAC1在突触传播是高度塑性且对兴奋性毒性损伤非常敏感的神经元中的区域富含。 EAAC1位于突触后膜上，是周围的胶水周围的倾斜度，理想位于微调突触传播。我们怀疑了解EAAC1的调节可能对理解谷氨酸毒性和/或突触可塑性具有影响。