Gene Regulation of Catecholamine Biosynthetic Enzymes by Nitric Oxide in PC12 Cells

Nitric oxide (NO) regulates a wide range of physiological processes. Recent studies show that NO can regulate the release of catecholamines (CA) from the adrenal medulla. In the current study, the PC12 cell line was used to examine the effect of NO on the regulation of the CA biosynthetic enzymes: tyrosine hydroxylase (TH), dopamine-β-hydroxylase (DBH) and phenylethanolamine Nmethyltransferase (PNMT). Treatment of PC12 cells with the NO donor, sodium nitroprusside (SNP) for 6 hours significantly increased TH, DBH and PNMT mRNA levels. In addition, NO potentiates the regulation of gene expression of all three CA biosynthetic enzymes by glucocorticoids and cholinergic agonists. The signaling pathways involved in NO regulation of CA biosynthetic enzymes were investigated with the use of specific kinase activators and inhibitors, with results supporting a contributing role of PKA, PKC and PKG in SNP-mediated induction for all three CA genes (p < 0.01). In addition, inhibitors of transcription and translation inhibited SNP-mediated induction of all three genes (p < 0.001) suggesting that both transcriptional and translational mechanisms may be involved in CA gene regulation by NO. Results from this study show that in addition to regulating CA biosynthetic enzymes, NO can also potentiate cholinergic and glucocorticoid activation of CA genes.