title: Roles of phosphoinositide-dependent kinase-1 in α1B-adrenoceptor phosphorylation and desensitization.
abstract: The role of phosphoinositide-dependent protein kinase-1 (PDK-1) activity on α(1B)-adrenoceptor phosphorylation and function was explored using pharmacological inhibitors and expression of a dominant-negative mutant of this enzyme. Noradrenaline-, phorbol myristate acetate-, lysophosphatidic acid- and epidermal growth factor-mediated α(1B)-adrenoceptor phosphorylation were markedly reduced by the two inhibitors used: UCN-01 [(7-hydroxystaurosporine; (3R*,8S*, 9R*, 10R*,12R*)-2,3,9,10,11,12-hexahydro-3-hydroxy-9-methoxy-8-methyl-10-(methylamino)-8,12-epoxy-1H, 8H-2,7b,12a-triazadibenzo[a,g]-cyclonona[cde]triden-1-one)] and OSU-03012 [(2-amino-N-[4-[5-(2-phenanthrenyl)-3-trifluoromethyl)-1H-pyrazol-1-yl]phenyl]-acetamide)]. A similar effect was observed in cells expressing a PDK-1 dominant-negative mutant. Phosphorylated PDK-1 (S241) and protein kinase C α (T497) were associated with cell membranes in the basal state which increased in response to the hormonal stimuli mentioned previously. UCN-01 essentially abolished phospho-PDK-1 membrane-association and markedly attenuated that of protein kinase C α. Consistent with the findings, UCN-01 reduced lysophosphatidic acid- and epidermal growth factor-induced α(1B-)adrenoceptor desensitization. Our data suggest that PDK-1 plays a permissive role in α(1B)-adrenoceptor desensitization and phosphorylation and participates in the formation of signaling complexes, which delicately modulate receptor function and regulation.
authors: Departamento de Biología Celular y Desarrollo, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Ap. Postal 70-248, D F 04510, Mexico.
authors: Rocío
authors: R
authors: Alcántara Hernández
authors: J Adolfo
authors: JA
authors: García-Sáinz
mesh_terms: D064413:3-Phosphoinositide-Dependent Protein Kinases; D000818:Animals; D019556:COS Cells; D002118:Calcium / Q000378:metabolism; D002522:Chlorocebus aethiops; D006224:Cricetinae; D042541:Intracellular Space / Q000187:drug effects / Q000378:metabolism; D009154:Mutation; D009638:Norepinephrine / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D018340:Receptors, Adrenergic, alpha-1 / Q000378:metabolism*; D019311:Staurosporine / Q000031:analogs & derivatives / Q000494:pharmacology
chemical_list: D047428:Protein Kinase Inhibitors; D018340:Receptors, Adrenergic, alpha-1; C054852:7-hydroxystaurosporine; D064413:3-Phosphoinositide-Dependent Protein Kinases; D017346:Protein Serine-Threonine Kinases; D019311:Staurosporine; D002118:Calcium; D009638:Norepinephrine