title: Regulation of expression of early growth response transcription factors in rat primary cortical neurons by extracellular ATP.
abstract: The zinc finger transcription factor early growth response-1 (Egr-1, NGFI-A, zif268, Krox 24, TIS8, ZENK) is upregulated immediately in the brain by cortical spreading depression (CSD) and other preconditioning stimuli and thus might participate in regulation of the overall genomic response to preconditioning. In the present study, the induction of expression of Egr-1 and other early growth response family members was characterized in rat primary cortical neuronal cultures. In neuronal cultures in vitro, depolarization or exposure to extracellular glutamate caused a 4-fold increase in egr-1 mRNA while exposure to extracellular ATP caused a 10-fold increase. The presence of mRNA encoding for multiple types of purinergic receptors was confirmed by RT-PCR. A number of nucleotide agonists proved effective in eliciting an increase in egr-1 mRNA. Over a limited range of concentration, the most effective agonists were ATP > ADP > alpha, beta-methylene ATP > UTP > cAMP > UDP > AMP > adenosine. Pertussis toxin, suramin, reactive blue 2, PPADS, DPCPX and inhibitors of Protein Kinase C, Protein Kinase A and PI3 kinase significantly reduced the upregulation of egr-1 by exposure to extracellular ATP. These findings suggest that neuronal metabotropic purinergic receptor activation contributes to the induction of early growth response transcription factors and may provide a target that can be manipulated to increase ischemic tolerance of the brain in vivo.
authors.affiliation: Department of Cellular and Molecular Medicine, University of Ottawa, 451 Smyth Road, Ottawa, Ontario, Canada.
authors.forename: Sarah C
authors.initials: SC
authors.lastname: McKee
authors.forename: Charlie S
authors.initials: CS
authors.lastname: Thompson
authors.forename: Luc A
authors.initials: LA
authors.lastname: Sabourin
authors.forename: Antoine M
authors.initials: AM
authors.lastname: Hakim
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000818:Animals; D015153:Blotting, Western / Q000379:methods; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology*; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D051766:Early Growth Response Protein 1 / Q000235:genetics / Q000378:metabolism*; D004622:Embryo, Mammalian; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects*; D018698:Glutamic Acid / Q000494:pharmacology; D007150:Immunohistochemistry / Q000379:methods; D009419:Nerve Tissue Proteins / Q000378:metabolism; D009474:Neurons / Q000187:drug effects*; D011189:Potassium Chloride / Q000494:pharmacology; D011247:Pregnancy; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D011983:Receptors, Purinergic / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D013997:Time Factors
chemical_list: D051766:Early Growth Response Protein 1; C486110:Egr1 protein, rat; D004791:Enzyme Inhibitors; D009419:Nerve Tissue Proteins; D012333:RNA, Messenger; D011983:Receptors, Purinergic; D018698:Glutamic Acid; D011189:Potassium Chloride; D000255:Adenosine Triphosphate