Astroglial Glutamate Transporters, Energetics, and Mitochondria

星形胶质细胞谷氨酸转运蛋白、能量学和线粒体

基本信息

批准号：
8678737
负责人：
Michael Byrne Robinson
金额：
$ 36.27万
依托单位：
CHILDREN'S HOSP OF PHILADELPHIA
依托单位国家：
美国
项目类别：
财政年份：
2012
资助国家：
美国
起止时间：
2012-08-01 至 2016-06-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8678737
关键词：
ATP phosphohydrolase Adult Amino Acids Anatomy Astrocytes Brain Brain Injuries Buffers Cell Death Cell membrane Cells Co-Immunoprecipitations Complex Cytoplasm Data Disease Electron Transport Complex III Environment Enzymes Excitatory Amino Acid Transporter 2 Failure Functional disorder GLAST Protein Glucose Glutamate Metabolism Pathway Glutamate Receptor Glutamate Transporter Glutamates Glutamine Glycolysis Goals Hippocampus (Brain)Image Immunoprecipitation Individual Link Mass Spectrum Analysis Measures Metabolism Mitochondria Mitochondrial Proteins Modeling Molecular Morphology Na(+)-K(+)-Exchanging ATPase Nerve Nervous system structure Neuraxis Neurodegenerative Disorders Neurodevelopmental Disorder Neurons Neurotransmitters Outer Mitochondrial Membrane Pathway interactions Process Production Proteins Publications Ranvier&apos s Nodes Receptor Cell Recruitment Activity Recycling Regulation Research Role Scaffolding Protein Signal Transduction Slice Stroke Synapses System Tertiary Protein Structure Testing Vertebral column base domain mapping extracellular hexokinase in vivo nervous system disorder novel oxidation presynaptic prevent relating to nervous system response scaffold spatial relationship stable isotope tool transmission process uptake

项目摘要

DESCRIPTION (provided by applicant): Glutamate is the predominant excitatory neurotransmitter in the mammalian central nervous system. An extracellular accumulation of glutamate causes excessive activation of glutamate receptors and cell death through excitotoxic mechanisms. Unlike other classical neurotransmitters, that are recycled directly into the presynaptic nerve terminal, most glutamate is cleared by two astroglial glutamate transporters, called GLAST and GLT-1 (or EAAT1 and EAAT2). These transporters maintain very low synaptic concentrations of glutamate, estimated at ~25 nM, in an environment that contains millimolar concentrations of glutamate. These transporters are enriched on the fine processes of astrocytes that sheath synapses. We recently developed physical evidence (co-immunoprecipitation, mass spectrometry, reverse immunoprecipitations) and anatomic evidence (co-localization in individual astrocytes in organotypic slice cultures) that these transporters exst in a complex with the Na+/K+ ATPase, most of the enzymes in glycolysis, and mitochondria. This complex is observed in fine processes of astroglia. In the first aim, we will identify specifi domains of GLT-1 and GLAST that support the interactions/co- compartmentalization. We wish to identify potential scaffolding proteins that may form a linkage between the transporters and mitochondria. As has been observed with mitochondria at synapses or at nodes of Ranvier, we propose that neural activity recruits mitochondria to regions where transporters are enriched. In the second aim, we will study the effects of neuronal activity on this co-compartmentalization and define the mechanisms involved. Finally, we will test the hypothesis that formation of these complexes is required for glutamate-dependent changes in glycolysis and a shift in glutamate metabolism (from conversion to glutamine to glutamate oxidation). Compartmentalization of the astroglial glutamate transporters with these proteins and mitochondria provides an opportunity to spatially match energy production and buffering capacity. It also has implications for disposition of the glutamate. Therefore, our proposed research will impact our understanding of fundamental aspects of glutamate handling and metabolism. They will also define a novel molecular mechanism that matches astroglial energetic demands to changes in neuronal activity.

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兴奋性神经递质。谷氨酸的细胞外积累导致谷氨酸受体的过度激活和细胞死亡通过兴奋性机制。与直接回收到突触前神经末端的其他经典神经递质不同，大多数谷氨酸都被两个星形胶质细胞谷氨酸转运蛋白清除，称为GLAST-1（或EAAT1和EAAT2）。这些转运蛋白在含有毫米浓度的谷氨酸的环境中保持非常低的谷氨酸突触浓度浓度，估计为约25 nm。这些转运蛋白富含鞘突触的星形胶质细胞的精细过程。我们最近开发了物理证据（共免疫沉淀，质谱法，反向免疫沉淀）和解剖学证据（器官型切片培养物中个体星形胶质细胞的共定位），这些转运蛋白与NA+/K+ ATPase的复合物相结合，大多数是glycochymes in Na+/k+ atpase的复杂性。在星形胶质细胞的细微过程中观察到了这种复合物。在第一个目的中，我们将确定支持相互作用/共隔室化的GLT-1和GLAST的特定域。我们希望确定可能在转运蛋白和线粒体之间形成联系的潜在脚手架蛋白。正如在突触或兰维尔节点处使用线粒体观察到的那样，我们提出神经活动将线粒体募集到富含转运蛋白的区域。在第二个目标中，我们将研究神经元活动对这种共同体化的影响，并定义所涉及的机制。最后，我们将检验以下假设：这些复合物的形成是谷氨酸依赖性糖酵解的变化和谷氨酸代谢的转移（从转化到谷氨酰胺再到谷氨酸氧化）所必需的。用这些蛋白质和线粒体对星形胶质细胞谷氨酸转运蛋白的隔室化为空间匹配能量生产和缓冲能力提供了机会。它也对谷氨酸的处置有影响。因此，我们提出的研究将影响我们对谷氨酸处理和代谢的基本方面的理解。他们还将定义一种新型的分子机制，该机制与星形胶质细胞的能量需求相匹配，以应对神经元活性的变化。