Role of transcription factor Egr-1 in phorbol ester-induced phenylethanolamine N-methyltransferase gene expression.
Transfection of PC12-variant RS1 cells with an Egr-1 expression construct has previously been shown to stimulate phenylethanolamine N-methyltransferase (PNMT) promoter activity, thus suggesting a putative role of Egr-1 as a factor regulating PNMT gene expression. To elucidate the physiological implication of this finding, the effects of phorbol 12-myristate 13-acetate (PMA) on PNMT promoter activity and Egr-1 expression were examined. PMA stimulated luciferase expression in RS1 cells transfected with a rat PNMT promoter-luciferase reporter gene construct, and also elevated both Egr-1 mRNA and Egr-1 protein levels in the untransfected cells. Further study on the concentration dependence of PMA action showed that the stimulation of luciferase expression correlated with the elevation of Egr-1 mRNA level. Finally, the stimulatory action of PMA on luciferase expression was dramatically diminished in the cells transfected with a mutant construct in which the Egr-1 binding site in PNMT promoter was mutated. These findings suggest that PMA-stimulated PNMT gene expression requires the enhancement of Egr-1 expression, thus providing further evidence for the physiological role of Egr-1 in the regulation of PNMT gene expression in the adrenergic cell.
Morita
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Nancy Pritzker Laboratory of Developmental and Molecular Neurobiology, Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, California 94305-5485, USA.
Ebert
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Wong
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D000818:Animals; D018076:DNA, Complementary; D004268:DNA-Binding Proteins / Q000096:biosynthesis* / Q000378:metabolism; D003907:Dexamethasone / Q000494:pharmacology; D051766:Early Growth Response Protein 1; D015870:Gene Expression / Q000187:drug effects*; D017874:Immediate-Early Proteins; D007700:Kinetics; D008156:Luciferases / Q000096:biosynthesis; D016716:PC12 Cells; D010625:Phenylethanolamine N-Methyltransferase / Q000096:biosynthesis*; D012333:RNA, Messenger / Q000032:analysis / Q000096:biosynthesis; D051381:Rats; D011965:Receptors, Glucocorticoid / Q000096:biosynthesis; D011994:Recombinant Proteins / Q000096:biosynthesis; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D013997:Time Factors; D014157:Transcription Factors / Q000096:biosynthesis* / Q000378:metabolism; D014162:Transfection; D016335:Zinc Fingers
D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D051766:Early Growth Response Protein 1; C486110:Egr1 protein, rat; D017874:Immediate-Early Proteins; D012333:RNA, Messenger; D011965:Receptors, Glucocorticoid; D011994:Recombinant Proteins; D014157:Transcription Factors; D003907:Dexamethasone; D008156:Luciferases; D010625:Phenylethanolamine N-Methyltransferase; D013755:Tetradecanoylphorbol Acetate