title: Down-regulation of protein kinase C in rat glioma C6 cells: effects on the beta-adrenergic receptor-coupled adenylate cyclase.
abstract: Continuous exposure of rat glioma C6 cells to 12-O-tetradecanoylphorbol-13-acetate (TPA) resulted in a time and dose dependent loss of [3H]phorbol dibutyrate binding sites and protein kinase C activity. Thus, by 24 h, the cells were essentially depleted of protein kinase C activity. In agreement with previous studies, TPA treatment caused a reduction in isoproterenol-stimulated adenylate cyclase activity and a sequestration of beta-adrenergic receptors. Cells were treated with TPA for 24-48 h to completely down-regulate protein kinase C and then exposed to isoproterenol. Agonist-mediated desensitization of adenylate cyclase and sequestration of beta-adrenergic receptors occurred at similar rates in control and TPA-treated cells. In addition, agonist-mediated down-regulation of beta-adrenergic receptors was not impaired by the absence of protein kinase C activity. Although both agonists and phorbol esters cause desensitization of the beta-adrenergic receptor-coupled adenylate cyclase, agonist-mediated events can occur independently of protein kinase C.
mesh_terms: D000262:Adenylyl Cyclases / Q000378:metabolism*; D000818:Animals; D029742:Caenorhabditis elegans Proteins; D002273:Carcinogens / Q000378:metabolism; D002352:Carrier Proteins; D002460:Cell Line; D005910:Glioma / Q000201:enzymology*; D007700:Kinetics; D015240:Phorbol 12,13-Dibutyrate; D010703:Phorbol Esters / Q000378:metabolism; D011493:Protein Kinase C / Q000378:metabolism*; D051381:Rats; D011943:Receptors, Adrenergic, beta / Q000378:metabolism*; D011955:Receptors, Drug; D011971:Receptors, Immunologic / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
chemical_list: D029742:Caenorhabditis elegans Proteins; D002273:Carcinogens; D002352:Carrier Proteins; D010703:Phorbol Esters; D011943:Receptors, Adrenergic, beta; D011955:Receptors, Drug; D011971:Receptors, Immunologic; C083141:phorbol ester binding protein; C027776:phorbol ester receptor; D015240:Phorbol 12,13-Dibutyrate; D011493:Protein Kinase C; D000262:Adenylyl Cyclases; D013755:Tetradecanoylphorbol Acetate