title: Protein kinase C deficiency blocks recovery from agonist-induced desensitization.
abstract: Protein phosphorylation is central to agonist-induced attenuation of the function of G-protein-linked receptors. Stable expression of RNA antisense to specific protein kinase mRNAs permitted analysis of loss-of-function mutants of A431 human epidermoid carcinoma cells, lacking protein kinase A, protein kinase C, or beta-adrenergic receptor kinase. Deficiency of protein kinase C, but not the others, amplified rather than attenuated agonist-induced desensitization. In wild-type cells, the t1/2 for recovery from desensitization was approximately 25 min following removal of agonist. In the protein kinase C-deficient cells, no resensitization was observed even 60 min after agonist removal. Like protein kinase C-deficiency, inhibition of protein kinase C with bisindolylmaleimide or calphostin C blocked resensitization. Resensitization was suppressed by FK506, an inhibitor of protein phosphatase 2B, mimicking protein kinase C-deficiency, but in a non-additive manner. The data reveal protein kinase C and protein phosphatase 2B to be critical elements of resensitization.
authors.affiliation: Department of Molecular Pharmacology, Diabetes & Metabolic Diseases Research Program, University Medical Center, SUNY/Stony Brook, Stony Brook, New York 11794-8651, USA.
authors.forename: M
authors.initials: M
authors.lastname: Shih
authors.forename: C C
authors.initials: CC
authors.lastname: Malbon
mesh_terms: D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D001483:Base Sequence; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D019204:GTP-Binding Proteins / Q000378:metabolism; D006801:Humans; D007211:Indoles / Q000494:pharmacology; D008301:Maleimides / Q000494:pharmacology; D008969:Molecular Sequence Data; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors; D011493:Protein Kinase C / Q000037:antagonists & inhibitors* / Q000378:metabolism; D016372:RNA, Antisense / Q000494:pharmacology; D011943:Receptors, Adrenergic, beta / Q000187:drug effects* / Q000378:metabolism; D016559:Tacrolimus / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D051552:beta-Adrenergic Receptor Kinases
chemical_list: D000318:Adrenergic beta-Agonists; D004791:Enzyme Inhibitors; D007211:Indoles; D008301:Maleimides; D016372:RNA, Antisense; D011943:Receptors, Adrenergic, beta; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C; D051552:beta-Adrenergic Receptor Kinases; D010749:Phosphoprotein Phosphatases; D019204:GTP-Binding Proteins; C088060:bisindolylmaleimide; D016559:Tacrolimus