title: ERK/MAPK is essential for endogenous neuroprotection in SCN2.2 cells.
abstract: BACKGROUND
  Glutamate (Glu) is essential to central nervous system function; however excessive Glu release leads to neurodegenerative disease. Strategies to protect neurons are underdeveloped, in part due to a limited understanding of natural neuroprotective mechanisms, such as those present in the suprachiasmatic nucleus (SCN). This study tests the hypothesis that activation of ERK/MAPK provides essential protection to the SCN after exposure to excessive Glu using the SCN2.2 cells as a model.
  
  
  METHODS
  Immortalized SCN2.2 cells (derived from SCN) and GT1-7 cells (neurons from the neighboring hypothalamus) were treated with 10 mM Glu in the presence or absence of the ERK/MAPK inhibitor PD98059. Cell death was assessed by Live/Dead assay, MTS assay and TUNEL. Caspase 3 activity was also measured. Activation of MAPK family members was determined by immunoblot. Bcl2, neuritin and Bid mRNA (by quantitative-PCR) and protein levels (by immunoblot) were also measured.
  
  
  RESULTS
  As expected Glu treatment increased caspase 3 activity and cell death in the GT1-7 cells, but Glu alone did not induce cell death or affect caspase 3 activity in the SCN2.2 cells. However, pretreatment with PD98059 increased caspase 3 activity and resulted in cell death after Glu treatment in SCN2.2 cells. This effect was dependent on NMDA receptor activation. Glu treatment in the SCN2.2 cells resulted in sustained activation of the anti-apoptotic pERK/MAPK, without affecting the pro-apoptotic p-p38/MAPK. In contrast, Glu exposure in GT1-7 cells caused an increase in p-p38/MAPK and a decrease in pERK/MAPK. Bcl2-protein increased in SCN2.2 cells following Glu treatment, but not in GT1-7 cells; bid mRNA and cleaved-Bid protein increased in GT1-7, but not SCN2.2 cells.
  
  
  CONCLUSIONS
  Facilitation of ERK activation and inhibition of caspase activation promotes resistance to Glu excitotoxicity in SCN2.2 cells.
  
  
  CONCLUSIONS
  Further research will explore ERK/MAPK as a key molecule in the prevention of neurodegenerative processes.
authors.affiliation: Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, Illinois, United States of America.
authors.forename: Sumedha W
authors.initials: SW
authors.lastname: Karmarkar
authors.forename: Kathleen M
authors.initials: KM
authors.lastname: Bottum
authors.forename: Stacey L
authors.initials: SL
authors.lastname: Krager
authors.forename: Shelley A
authors.initials: SA
authors.lastname: Tischkau
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D051023:BH3 Interacting Domain Death Agonist Protein / Q000235:genetics / Q000378:metabolism; D015153:Blotting, Western; D053148:Caspase 3 / Q000378:metabolism; D002460:Cell Line; D016291:Dizocilpine Maleate / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D048049:Extracellular Signal-Regulated MAP Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D005419:Flavonoids / Q000494:pharmacology; D058851:GPI-Linked Proteins / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression / Q000187:drug effects; D018698:Glutamic Acid / Q000494:pharmacology; D007150:Immunohistochemistry; D020935:MAP Kinase Signaling System / Q000187:drug effects; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D008959:Models, Neurological; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D009479:Neuropeptides / Q000235:genetics / Q000378:metabolism; D018696:Neuroprotective Agents / Q000037:antagonists & inhibitors / Q000378:metabolism*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism; D051381:Rats; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013493:Suprachiasmatic Nucleus / Q000166:cytology / Q000378:metabolism
chemical_list: D051023:BH3 Interacting Domain Death Agonist Protein; C494816:Bid protein, rat; D005419:Flavonoids; D058851:GPI-Linked Proteins; D009479:Neuropeptides; D018696:Neuroprotective Agents; C105161:Nrn1 protein, rat; D019253:Proto-Oncogene Proteins c-bcl-2; D016194:Receptors, N-Methyl-D-Aspartate; D018698:Glutamic Acid; D016291:Dizocilpine Maleate; D048049:Extracellular Signal-Regulated MAP Kinases; D020928:Mitogen-Activated Protein Kinases; D053148:Caspase 3; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one