MT COBRE: MOLEC MODULATION OF GLUTAMATE TRANSPORTER EXPRESSION: AIDS DEMENTIA

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Prolonged increases in the extracellular concentration of glutamate result in the over stimulation of glutamate receptors and leads to the excitotoxic death of neurons. Excitotoxicity has been associated with a number of chronic, and acute neurodegenerative diseases including, Amyotrophic lateral sclerosis (ALS), epilepsy, Parkinson's disease, Huntingtons' disease, AIDS dementia, glaucoma, ischemia and brain trauma. A system of Na-dependent, high affinity, excitatory amino acid (EAA) transporters plays a critical role in regulating the extracellular concentrations of glutamate within the CNS and thus maintains the balance between physiological and pathological conditions. The rapid clearance of glutamate by these transporters facilitates signal termination, transmitter recycling, and the maintenance of glutamate below excitotoxic levels. A variety of substrate and nonsubstrate inhibitors of the glutamate transporters have been used to study the functional roles of these important proteins. Unfortunately, none of the glutamate transporter inhibitors characterized to date have the ability to act in a cell type specific manner and only a limited number of these inhibitors exhibit transporter isotype specificity. This lack of transporter and cell type specificity has led to conflicting opinions regarding the roles of specific transporter isotypes in neuroprotection and neurodegeneration associated with excitotoxic disease. In order to address this deficiency, we propose to use AAV1 vectors to establish cell type-specific overexpression and knock down of recombinant EAAT2 and EAAT3 in murine hippocampal slice cultures. Using this in vitro model, we will examine the impact of modified transporter expression on the cellular localization of these transporters as well as other critical glutamate receptors. Furthermore, we will examine the effect of overexpressing recombinant transporters on functional uptake activity in neurons and astrocytes. Most importantly, we will investigate the contribution of specific transporter isotypes to neuroprotection and neurodegeneration following an excitotoxic insult.