GLUTAMATE TRANSPORTERS IN THE CNS

Summary

Principal Investigator: LINDSEY GARFIELD
Abstract: The acidic amino acid, glutamate, is the predominant excitatory neurotransmitter in the mammalian central nervous system. Although there are millimolar concentrations of this excitatory amino acid (EAA) in the brain, extracellular concentrations are maintained in the low micromolar range to facilitate crisp synaptic transmission and to prevent excessive activation of receptors that can kill neurons (or other cells that express glutamate receptors). A family of Na^-dependent high- affinity glutamate transporters is responsible for the regulation and clearance of extracellular EAAs. This project represents a collaborative effort between two laboratories that have contributed to our understanding of the biochemical, pharmacologic, anatomic, and pathophysiologic properties of these transporters. In this competitive renewal, we propose to continue focusing on one of the astroglial glutamate transporters, called GLT-1 or EAAT2. There is substantial evidence to suggest that this transporter mediates the largest percentage of glutamate uptake activity in the forebrain. The expression (mRNA and protein) of GLT-1/EAAT2 increases during synaptogenesis in vivo and is induced in astrocytes in vitro by the presence of neurons. Lesions of projection neurons in vivo results in decreased GLT-1/EAAT2 expression in target areas. In addition, several acute and chronic neurodegenerative diseases (or animal models of these diseases) are accompanied by decreased expression of GLT-1/EAAT2. Based on our prior studies and our preliminary data, we propose to identify signals/transcription factors and promoter elements that contribute to basal and 'neuron- dependent'induction of GLT-1/EAAT2 (Aims I &II). In pur preliminary studies, we have also identified fragments of the GLT-1/EAAT2 5'non-coding region that contain elements that suppress transcription. These elements will also be characterized (Aims I &II). As we identify elements that are required for induction/suppression of GLT-1 expression, these elements will be introduced into models of neurologic insults with the goal of determining if the presence damaged/dying neurons results in decreased promoter activation or results in active suppression of GLT-1 transcription. With this approach, we hope to develop an understanding of the mechanisms that regulate the expression of the predominant protein that limits excitability in the normal nervous system and to develop an understanding of the factors that may contribute to the loss of this protein in both acute and chronic neurodegenerative diseases. Children's Hospital of Philadelphia, Philadelphia, Pennsylvania The Johns Hopkins School of Medicine, Baltimore, Maryland PHS 398 (Rev.09/04) Page 2 Form Page2 Principal Investigator/Program Director (Last, First, Middle): Robinson, Michael B. KEY PERSONNEL. See instructions. Use continuation pages as neededto provide the required information in the format shown below. Start with Principal Investigator. List all other key personnel in alphabetical order, last name first. Name eRA Commons User Name Organization Role on Project Michael B. Robinson, Ph.D. Michael_Robinson Children's Hospital PI Jeffrey Rothstein, MD PhD JRothstl Johns Hopkins Co-Pi OTHER SIGNIFICANT CONTRIBUTORS Name Organization Role on Project Beverly Davidson, Ph.D. University of Iowa Consultant Shelley Russek, Ph.D. Boston University Consultant John Wolfe, V.M.D./Ph.D. CHOP/University of Pennsylvania Consultant Human Embryonic Stem Cells X No CH Yes If the proposed project Involves human embryonic stem cells, list below the registration number of the specific cell llne(s) from the following list: http://stemcells.nih.gov/reqistrv/index.asp. Usecontinuationpagesasneeded. If a specific line cannot be referenced at this time, include a statement that onefrom the Registry will be used. Cell Line Disclosure Permission Statement. Applicable toSBIR/STTR Only. See SBIR/STTR instructions. 0 Yes O No PHS 398 (Rev.09/04) Page 3 Form Page 2-continued Number the following pages consecutively throughout the application. Do not use suffixes such as 4a, 4b. Principal Investigator/Program Director (Last, First, Middle): Robinson, Michael B. The name of the principal investigator/program director must be provided at the top of each printed page and each continuation page. RESEARCH GRANT TABLE OF CONTENTS Page Numbers Face Page i_ Description,
Funding Period: ----------------1997 - ---------------2011-
more information: NIH RePORT

Top Publications

  1. ncbi Selective up-regulation of the glial Na+-dependent glutamate transporter GLT1 by a neuroimmunophilin ligand results in neuroprotection
    Raquelli Ganel
    Department of Neurology, Johns Hopkins University, Baltimore, MD 21287, USA
    Neurobiol Dis 21:556-67. 2006
  2. pmc Ubiquitination-mediated internalization and degradation of the astroglial glutamate transporter, GLT-1
    Amanda L Sheldon
    Department of Pediatrics, Children s Hospital of Philadelphia, University of Pennsylvania, Philadelphia, PA 19104, USA
    Neurochem Int 53:296-308. 2008
  3. ncbi The endoplasmic reticulum exit of glutamate transporter is regulated by the inducible mammalian Yip6b/GTRAP3-18 protein
    ALICIA M RUGGIERO
    Department of Neuroscience, Johns Hopkins University, 625 N Wolfe Street, Baltimore, MD 21287, USA
    J Biol Chem 283:6175-83. 2008
  4. pmc The role of glutamate transporters in neurodegenerative diseases and potential opportunities for intervention
    Amanda L Sheldon
    Department of Neuroscience, University of Pennsylvania, Philadelphia, PA 19104 4318, United States
    Neurochem Int 51:333-55. 2007
  5. ncbi Analysis of cerebellar Purkinje cells using EAAT4 glutamate transporter promoter reporter in mice generated via bacterial artificial chromosome-mediated transgenesis
    Dan Gincel
    Department of Neurology, Johns Hopkins University, Baltimore, MD 21287, USA
    Exp Neurol 203:205-12. 2007
  6. ncbi Regulation of astrocytic glutamate transporter expression by Akt: evidence for a selective transcriptional effect on the GLT-1/EAAT2 subtype
    Li Bin Li
    Department of Pediatrics, University of Pennsylvania, Philadelphia, Pensylvania 19104 4318, USA
    J Neurochem 97:759-71. 2006
  7. ncbi Impaired glutamate transport in a mouse model of tau pathology in astrocytes
    Deepa V Dabir
    Center for Neurodegenerative Disease Research, Department of Pathology and Laboratory Medicine, Children s Hospital of Philadelphia, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA
    J Neurosci 26:644-54. 2006
  8. pmc Neuronal exosomal miRNA-dependent translational regulation of astroglial glutamate transporter GLT1
    Lydie Morel
    Department of Neuroscience, Tufts University, Boston, Massachusetts 02111, USA
    J Biol Chem 288:7105-16. 2013
  9. pmc Presynaptic regulation of astroglial excitatory neurotransmitter transporter GLT1
    Yongjie Yang
    Department of Neurology and Neuroscience, Johns Hopkins University, Baltimore, MD 21287, USA
    Neuron 61:880-94. 2009
  10. pmc Epigenetic regulation of neuron-dependent induction of astroglial synaptic protein GLT1
    Yongjie Yang
    Department of Neurology, Johns Hopkins University, 600 N Wolfe Street, Baltimore, MD 21287, USA
    Glia 58:277-86. 2010

Detail Information

Publications11

  1. ncbi Selective up-regulation of the glial Na+-dependent glutamate transporter GLT1 by a neuroimmunophilin ligand results in neuroprotection
    Raquelli Ganel
    Department of Neurology, Johns Hopkins University, Baltimore, MD 21287, USA
    Neurobiol Dis 21:556-67. 2006
    ..These studies suggest that neuroimmunophilins can regulate GLT1 and that their ligands could serve as therapies for neurodegenerative disorders...
  2. pmc Ubiquitination-mediated internalization and degradation of the astroglial glutamate transporter, GLT-1
    Amanda L Sheldon
    Department of Pediatrics, Children s Hospital of Philadelphia, University of Pennsylvania, Philadelphia, PA 19104, USA
    Neurochem Int 53:296-308. 2008
    ..Together these data define a novel mechanism by which the predominant forebrain glutamate transporter can be rapidly targeted for degradation...
  3. ncbi The endoplasmic reticulum exit of glutamate transporter is regulated by the inducible mammalian Yip6b/GTRAP3-18 protein
    ALICIA M RUGGIERO
    Department of Neuroscience, Johns Hopkins University, 625 N Wolfe Street, Baltimore, MD 21287, USA
    J Biol Chem 283:6175-83. 2008
    ..The features of GTRAP3-18 activity are consistent with recent phylogenic sequence analyses suggesting GTRAP3-18 and JM4 be reclassified as mammalian isoforms of the yeast protein family Yip, Yip6b, and Yip6a, respectively...
  4. pmc The role of glutamate transporters in neurodegenerative diseases and potential opportunities for intervention
    Amanda L Sheldon
    Department of Neuroscience, University of Pennsylvania, Philadelphia, PA 19104 4318, United States
    Neurochem Int 51:333-55. 2007
    ....
  5. ncbi Analysis of cerebellar Purkinje cells using EAAT4 glutamate transporter promoter reporter in mice generated via bacterial artificial chromosome-mediated transgenesis
    Dan Gincel
    Department of Neurology, Johns Hopkins University, Baltimore, MD 21287, USA
    Exp Neurol 203:205-12. 2007
    ..The correlation of promoter activity to protein expression makes the EAAT4 BAC promoter reporter a valuable tool to study regulation of EAAT4 expression...
  6. ncbi Regulation of astrocytic glutamate transporter expression by Akt: evidence for a selective transcriptional effect on the GLT-1/EAAT2 subtype
    Li Bin Li
    Department of Pediatrics, University of Pennsylvania, Philadelphia, Pensylvania 19104 4318, USA
    J Neurochem 97:759-71. 2006
    ..From these studies, we conclude that Akt induces the expression of GLT-1 through increased transcription and that Akt can regulate GLT-1 expression without increasing GLAST expression in astrocytes...
  7. ncbi Impaired glutamate transport in a mouse model of tau pathology in astrocytes
    Deepa V Dabir
    Center for Neurodegenerative Disease Research, Department of Pathology and Laboratory Medicine, Children s Hospital of Philadelphia, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA
    J Neurosci 26:644-54. 2006
    ..Thus, these Tg mice recapitulate features of astrocytic pathology observed in tauopathies and implicate a role for altered astrocyte function in the pathogenesis of these disorders...
  8. pmc Neuronal exosomal miRNA-dependent translational regulation of astroglial glutamate transporter GLT1
    Lydie Morel
    Department of Neuroscience, Tufts University, Boston, Massachusetts 02111, USA
    J Biol Chem 288:7105-16. 2013
    ..Together, our study characterized a new neuron-to-astrocyte communication pathway and identified miRNAs that modulate GLT1 protein expression in astrocytes in vitro and in vivo...
  9. pmc Presynaptic regulation of astroglial excitatory neurotransmitter transporter GLT1
    Yongjie Yang
    Department of Neurology and Neuroscience, Johns Hopkins University, Baltimore, MD 21287, USA
    Neuron 61:880-94. 2009
    ..Presynaptic elements dynamically coordinate normal astroglial function and also provide a fundamental signaling mechanism by which altered neuronal function and injury leads to dysregulated astroglia in CNS disease...
  10. pmc Epigenetic regulation of neuron-dependent induction of astroglial synaptic protein GLT1
    Yongjie Yang
    Department of Neurology, Johns Hopkins University, 600 N Wolfe Street, Baltimore, MD 21287, USA
    Glia 58:277-86. 2010
    ..In summary, hypermethylation on selective CpG sites of the GLT1 promoter is involved in repression of GLT1 promoter activation, but this regulation does not play a role in astroglial dysfunction of EAAT2 expression in patients with ALS...
  11. pmc Nuclear factor-κB contributes to neuron-dependent induction of glutamate transporter-1 expression in astrocytes
    Mausam Ghosh
    Department of Pediatrics, Children s Hospital of Philadelphia, University of Pennsylvania, Philadelphia, Pennsylvania 19104 4318, USA
    J Neurosci 31:9159-69. 2011
    ..Together, these studies strongly suggest that NF-κB contributes to neuron-dependent regulation of astrocytic GLT-1 transcription...