title: Phorbol ester activation of protein kinase C inhibits CNP-stimulated cyclic GMP production in the mouse AtT-20 pituitary tumour cell line.
abstract: Preincubation of AtT-20 mouse pituitary tumour cells with the phorbol ester PMA resulted in a concentration-dependent inhibition of CNP-stimulated cyclic GMP production. The phorbol ester analogue 4 alpha phorbol had no inhibitory effect and 24 h preincubations with PMA resulted in a characteristic down-regulation of the response indicating that the inhibitory actions were mediated via the activation of protein kinase C. Forskolin in the presence of the phosphodiesterase inhibitor IBMX stimulated intracellular cyclic AMP concentrations by up to eight fold, but did not alter basal nor CNP-stimulated cyclic GMP production. These results indicate that CNP-stimulated guanylate cyclase activity associated with the GC-B natriuretic peptide receptor expressed in AtT-20 cells is inhibited by protein kinase C.
authors.affiliation: Molecular Endocrinology Group, School of Biological and Medical Sciences, University of St Andrews, UK.
authors.forename: A F
authors.initials: AF
authors.lastname: Gilkes
authors.forename: S B
authors.initials: SB
authors.lastname: Guild
authors.forename: G
authors.initials: G
authors.lastname: Cramb
mesh_terms: D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D000818:Animals; D009320:Atrial Natriuretic Factor / Q000494:pharmacology; D002460:Cell Line; D005576:Colforsin / Q000494:pharmacology; D006152:Cyclic GMP / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation; D007700:Kinetics; D051379:Mice; D020098:Natriuretic Peptide, C-Type; D010911:Pituitary Neoplasms; D011493:Protein Kinase C / Q000378:metabolism*; D011506:Proteins / Q000494:pharmacology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D013997:Time Factors; D014407:Tumor Cells, Cultured
chemical_list: D011506:Proteins; D020098:Natriuretic Peptide, C-Type; D005576:Colforsin; D009320:Atrial Natriuretic Factor; D011493:Protein Kinase C; D006152:Cyclic GMP; D013755:Tetradecanoylphorbol Acetate; D015056:1-Methyl-3-isobutylxanthine