Role of transcription factor Egr-1 in phorbol ester-induced phenylethanolamine N-methyltransferase gene expression

Morita, K.; Ebert, S.N.; Wong, D.L.

Journal of Biological Chemistry 270(19): 11161-11167


ISSN/ISBN: 0021-9258
PMID: 7744747
DOI: 10.1074/jbc.270.19.11161
Accession: 009371332

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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.