title: Protein kinase A and protein kinase C signaling pathway interaction in phenylethanolamine N-methyltransferase gene regulation.
abstract: The protein kinase A (PKA) and protein kinase C (PKC) signaling pathways appear to interact in regulating phenylethanolamine N-methyltransferase (PNMT) promoter-driven gene transcription in PC12 cells. Forskolin treatment of cells transfected with the rat PNMT promoter-luciferase reporter gene construct pGL3RP893 increased promoter activity approximately two-fold whereas phorbol-12-myristate-13 acetate (PMA) treatment had no effect. However, simultaneous forskolin and PMA treatment synergistically activated the PNMT promoter approximately four-fold, suggesting that PKC stimulation requires prior induction of the PKA pathway. Consistent with this possibility the adenylate cyclase inhibitor MDL12,330A, and the PKA inhibitor H-89 prevented PNMT promoter stimulation by the combination of forskolin and PMA. PKA and PKC regulation seems to be mediated in part by Egr-1 and Sp1 through their consensus elements in the PNMT promoter. Forskolin and PMA treatment of PC12 cells increased Egr-1 protein and phosphorylated Egr-1/DNA-binding complex formation to the same extent but only increased phosphorylated Sp1/DNA binding complex formation without altering Sp1 protein levels. Mutation of the - 165 bp Egr-1 and - 48 bp Sp1 sites, respectively, attenuated and abolished combined forskolin and PMA-mediated promoter activation. PNMT promoter analysis further showed that synergistic stimulation by PKA and PKC involves DNA sequences between - 442 and - 392 bp, and potentially a GCM binding element lying within this region.
authors.affiliation: Department of Psychiatry, Harvard Medical School, Laboratory of Molecular and Developmental Neurobiology, McLean Hospital, Belmont, Massachusetts 02478, USA.
authors.forename: T C
authors.initials: TC
authors.lastname: Tai
authors.forename: Dona L
authors.initials: DL
authors.lastname: Wong
mesh_terms: D000818:Animals; D005576:Colforsin / Q000494:pharmacology; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D051766:Early Growth Response Protein 1; D020536:Enzyme Activators / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000502:physiology*; D017874:Immediate-Early Proteins; D046911:Macromolecular Substances; D016716:PC12 Cells; D010625:Phenylethanolamine N-Methyltransferase / Q000235:genetics*; D011401:Promoter Regions, Genetic / Q000502:physiology; D011493:Protein Kinase C / Q000378:metabolism*; D051381:Rats; D011965:Receptors, Glucocorticoid / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*; D016329:Sp1 Transcription Factor / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014157:Transcription Factors / Q000378:metabolism
chemical_list: D004268:DNA-Binding Proteins; D051766:Early Growth Response Protein 1; C486110:Egr1 protein, rat; D020536:Enzyme Activators; D017874:Immediate-Early Proteins; D046911:Macromolecular Substances; D011965:Receptors, Glucocorticoid; D016329:Sp1 Transcription Factor; D014157:Transcription Factors; D005576:Colforsin; D004247:DNA; D010625:Phenylethanolamine N-Methyltransferase; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate