Synaptic Glutamate Receptor Trafficking.

突触谷氨酸受体贩运。

• 批准号: 7625908
• 负责人: ROGER A NICOLL
• 金额: $ 54.97万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN FRANCISCO
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-06-01 至 2012-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7625908
• 关键词: AMPA Receptors; Accounting; Address; Animals; Brain; Cell surface; Clinical; Defect; Development; Drug Design; Ensure; Epilepsy; Excitatory Synapse; Genes; Glutamate Receptor; Glutamates; Grant; Hippocampus (Brain); Integral Membrane Protein; Kinetics; Learning; Mediating; Membrane; Memory; Molecular; Mus; Mutant Strains Mice; Mutate; Mutation; N-Methyl-D-Aspartate Receptors; Nature; Nervous system structure; Neuroglia; Neurons; Newborn Infant; Play; Progress Reports; Property; Protein Family; Proteins; Receptor Activation; Regulation; Research; Research Personnel; Role; SHPS-1 protein; Series; Spinal Cord; Surface; Synapses; Synaptic Transmission; Synaptic plasticity; Work; base; density; genetic regulatory protein; granule cell; insight; novel; programs; pup; receptor; receptor function; research study; stargazin; success; trafficking; transmission process

DESCRIPTION (provided by applicant): Excitatory synapses in the CNS release glutamate, which acts on two types of ionotropic receptors: AMPA receptors (AMPARs) and NMDA receptors (NMDARs). Evidence indicates that AMPARs, in contrast to NMDARs, are highly mobile and that activity can rapidly change the number of receptors at the synapse. To begin to understand the molecular basis underlying the regulation of synaptic AMPARs, we have focused on the ataxic and epileptic mouse stargazer. Cerebellar granule cells in this mouse lack functional AMPARs, although NMDARs are normal and excitatory synapses release normal amounts of glutamate. During the current Conte grant we have carried out a series of studies on the role of stargazin (v-2), the mutated gene in the stargazer mouse. We have found that stargazin is an auxiliary subunit of AMPARs, not only controlling their trafficking to the cell surface and to the synapse, but also controlling their biophysical properties. We have identified a total of three additional proteins (v-3, y-4, v-8) that are expressed throughout the CNS and can rescue the AMPAR defect in cerebellar granule cells. We refer to these proteins as transmembrane AMPAR regulatory proteins (TARPs). We have succeeded in deleting the gene for each of the TARPs in mice. These mutant mice will form the basis for many of the proposed experiments in this RO1 grant, which is a continuation of the work carried out on the Conte Grant. There are 4 Specific Aims. (1) Determine the role of v-3 in the mouse brain, (2) determine the role of y-4 in the mouse brain, (3) determine the functional differences among TARPs, and (4) determine whether TAPRs may have AMPAR-independent roles in the CNS. The role of TARPs in AMPAR trafficking, synaptic transmission and plasticity will be studied primarily in the hippocampus. Preliminary studies indicate that y-8 plays an important role in AMPAR trafficking in the hippocampus, but substantial AMPAR transmission remains. We will also compare the ability of various TARPs to modify the deactivation of AMPARs and the kinetics of synaptic transmission. We have evidence that each of the roles TARPs play (i.e., surface delivery, synaptic targeting and receptor gating) all vary for each of the TARPs. We have found that the Y-2/Y-3A/-4, triple KO is lethal and the newborn pups are completely immobile. We will determine why the spinal cord is nonfunctional. These studies may uncover novel roles for TARPs in the nervous system. Given the critical role that receptor trafficking plays in synaptic plasticity and, by implication in certain aspects of learning and memory, it is anticipated that findings from these studies will have direct clinical impact. Indeed, clinically promising AMPAkines exert their effect, in part, by controlling the kinetics of AMPAR gating similar to TARPs. In addition, TARPs modify the pharmacological properties of AMPAkines and, thus, represent a novel target for drug design.

描述（由申请人提供）：中枢神经系统中的兴奋性突触释放谷氨酸，谷氨酸作用于两种类型的离子型受体：AMPA受体（AMPAR）和NMDA受体（NMDAR）。有证据表明，与 NMDAR 相比，AMPAR 具有高度移动性，并且其活动可以迅速改变突触处受体的数量。为了开始了解突触 AMPAR 调节的分子基础，我们重点研究了共济失调和癫痫小鼠观星者。尽管 NMDAR 正常且兴奋性突触释放正常量的谷氨酸，但该小鼠的小脑颗粒细胞缺乏功能性 AMPAR。在当前的 Conte 资助期间，我们对观星小鼠中的突变基因 stargazin (v-2) 的作用进行了一系列研究。我们发现stargazin是AMPAR的辅助亚基，不仅控制它们向细胞表面和突触的运输，而且还控制它们的生物物理特性。我们已经鉴定出总共三种额外的蛋白质（v-3、y-4、v-8），它们在整个中枢神经系统中表达，可以挽救小脑颗粒细胞中的 AMPAR 缺陷。我们将这些蛋白质称为跨膜 AMPAR 调节蛋白 (TARP)。我们已经成功删除了小鼠体内每个 TARP 的基因。这些突变小鼠将构成本次 RO1 资助中许多拟议实验的基础，这是 Conte 资助中开展的工作的延续。有 4 个具体目标。 (1) 确定 v-3 在小鼠大脑中的作用，(2) 确定 y-4 在小鼠大脑中的作用，(3) 确定 TARP 之间的功能差异，以及 (4) 确定 TAPR 在 CNS 中是否具有 AMPAR 独立作用。 TARP 在 AMPAR 运输、突触传递和可塑性中的作用将主要在海马体中进行研究。初步研究表明 y-8 在海马 AMPAR 转运中发挥重要作用，但大量 AMPAR 传输仍然存在。我们还将比较各种 TARP 改变 AMPAR 失活和突触传递动力学的能力。我们有证据表明，TARP 发挥的每个作用（即表面传递、突触靶向和受体门控）对于每个 TARP 来说都是不同的。我们发现Y-2/Y-3A/-4，三重KO是致命的，新生幼崽完全无法动弹。我们将确定脊髓无功能的原因。这些研究可能会揭示 TARP 在神经系统中的新作用。鉴于受体运输在突触可塑性中发挥的关键作用，以及对学习和记忆某些方面的影响，预计这些研究的结果将产生直接的临床影响。事实上，临床上有前景的 AMPAkine 发挥作用的部分原因是控制与 TARP 类似的 AMPAR 门控动力学。此外，TARP 改变了 AMPAkines 的药理学特性，因此代表了药物设计的新靶点。