Research Interests:

Glutamate transporters in the mammalian CNS.

Keywords:

Glutamate, transporters, excitotoxicity.

Research Summary:

Glutamate and aspartate are the predominant excitatory neurotransmitters in the mammalian CNS. In addition to mediating rapid synaptic depolarization, these excitatory amino acids (EAAs) have been implicated in diverse processes, including synaptic plasticity and synapse formation. There is also evidence that prolonged and/or excessive activation of EAA receptors contributes to the neuronal death that occurs in many acute insults to the CNS, such as hypoxia/ischemia, hypoglycemia and head trauma. Dr. Robinson's research focuses on defining endogenous mechanisms that may normally protect the brain from this excitotoxicity. At this time, the primary emphasis of the laboratory is the family of sodium-dependent high affinity transport systems that directly regulate extracellular EAAs. We are studying both the transcriptional and post-translational regulation of these transporters. We have found that neurons actively participate in the regulation of the expression of the glial glutamate transporters. We are defining the signaling molecules involved in this regulation. We have also found that the activity and cell surface expression of many of these transporters can be regulated acutely (within min). We are understanding the mechanisms involved in this regulation with the goal of defining the physiological relevance. The laboratory uses molecular biological, biochemical/cell biological, and other complimentary strategies to study these problems.

Potential Lab Rotation Projects:

•  Determine if PKC causes redistribution of the transporters through direct phosphorylation.

•  Study domains and interacting proteins required for assembly of the transporters in the endoplasmic reticulum and forward trafficking of the transporters after terminal glycosylation in the Golgi.

•  Develop methods to purify vesicles that express one of the neuronal glutamate transporters with the goal of identifying other proteins that also exist on the vesicles.

•  Express specific signaling molecules in astrocytes using lentiviral vectors to study the regulation of expression of the glial glutamate transporters.

•  Over-express transporters using lentiviral vectors to determine if transporters are neuroprotective in model systems.

•  Other potential projects can be discussed.

Key References:

Crino P.B., Jin H., Robinson M.B., Coulter D., Brooks-Kayal A. Increased expression of the neuronal glutamate transporter (EAAT3/EAAC1) in hippocampal and neocortical epilepsy. Epilepsia 43 (2002) 211-218.

González M.I., Kazanietz M.G., and Robinson M.B. Regulation of the neuronal glutamate transporter, excitatory amino acid carrier-1 (EAAC1), by different protein kinase C subtypes. Mol. Pharm. 62 (2002) 901-910.

Kalandadze A., Wu Y., and Robinson M.B. Protein kinase C activation decreases cell surface expression of the GLT-1 subtype of glutamate transporter: Requirement of a carboxy-terminal domain and partial dependence on serine-486. J. Biol. Chem . 277 (2002) 45741-45750 .

González M.I., and Robinson M.B. Phorbol myristate acetate-dependent interaction of protein kinase Ca and the neuronal glutamate transporter EAAC1. J. Neurosci 23 (2003) 5589-5593.

Susarla B. T.S., and Robinson M.B. Rottlerin, an inhibitor of protein kinase Ca, inhibits astrocytic glutamate transport activity and reduces GLAST immunoreactivity by a mechanism that appears to be PKC? independent. J. Neurochem . 86 (2003) 635-645.

Robinson M.B. Regulated trafficking of neurotransmitter transporters: Common notes but different melodies. J. Neurochem. 80 (2002) 1-11.

Lab Personnel:

Willie Bergman
Keith Fournier
Marco González
Avtandil Kalandadze
Elizabeth Krizman
Lebin Li
Crystal Saunders
Amanda Sheldon
Bala Susarla