title: Role of PKCα-p38 MAPK-Giα axis in peroxynitrite-mediated inhibition of β-adrenergic response in pulmonary artery smooth muscle cells.
abstract: In the context of cross-talk between transmembrane signaling pathways, we studied the loci within the β-adrenergic receptor/G protein/adenyl cyclase system at which PKC exerts regulatory effects of peroxynitrite (ONOO(-)) on isoproterenol stimulated adenyl cyclase activity in pulmonary artery smooth muscle cells. Treatment of the cells with ONOO(-) stimulated PKC-α activity and that subsequently increased p(38)MAPK phosphorylation. Pretreatment with Go6976 (PKC-α inhibitor) and SB203580 (p(38)MAPK inhibitor) eliminated ONOO(-) caused inhibition on isoproterenol stimulated adenyl cyclase activity. Pretreatment with Go6976, but not SB203580, prevented ONOO(-) induced increase in PKC-α activity. Studies using genetic inhibitors of PKC-α (PKC-α siRNA) and p(38)MAPK (p(38)MAPK siRNA) also corroborated the findings obtained with their pharmacological inhibitors in eliminating the attenuation of ONOO(-) effect on isoproterenol stimulated adenyl cyclase activity. This inhibitory effect of ONOO(-) was found to be eliminated upon pretreatment of the cells with pertussis toxin thereby pointing to a G(i) dependent mechanism. This hypothesis was reinforced by G(i)α phosphorylation as well as by the observation of the loss of the ability of Gpp(NH)p (a measure of G(i) mediated response) to stimulate adenyl cyclase activity upon ONOO(-) treatment to the cells. We suggest the existence of a pertussis toxin sensitive G protein (G(i))-mediated mechanism in isoproterenol stimulated adenyl cyclase activity, which is regulated by PKCα-p(38)MAPK axis dependent phosphorylation of its α-subunit (G(i)α) in the pulmonary artery smooth muscle cells.
authors.affiliation: Department of Biochemistry and Biophysics, University of Kalyani, Kalyani 741235, West Bengal, India. sajal_chakraborti@yahoo.com
authors.forename: Sajal
authors.initials: S
authors.lastname: Chakraborti
authors.forename: Soumitra
authors.initials: S
authors.lastname: Roy
authors.forename: Animesh
authors.initials: A
authors.lastname: Chowdhury
authors.forename: Amritlal
authors.initials: A
authors.lastname: Mandal
authors.forename: Tapati
authors.initials: T
authors.lastname: Chakraborti
mesh_terms: D000262:Adenylyl Cyclases / Q000378:metabolism; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology*; D000818:Animals; D002227:Carbazoles / Q000494:pharmacology; D002417:Cattle; D002460:Cell Line; D000242:Cyclic AMP / Q000378:metabolism; D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000378:metabolism*; D007545:Isoproterenol / Q000494:pharmacology; D032389:Myocytes, Smooth Muscle / Q000166:cytology / Q000378:metabolism; D030421:Peroxynitrous Acid / Q000494:pharmacology*; D037342:Pertussis Toxin / Q000494:pharmacology; D010766:Phosphorylation; D051571:Protein Kinase C-alpha / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D011651:Pulmonary Artery; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000378:metabolism; D011943:Receptors, Adrenergic, beta / Q000737:chemistry* / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*
chemical_list: D000319:Adrenergic beta-Antagonists; D002227:Carbazoles; D034741:RNA, Small Interfering; D011943:Receptors, Adrenergic, beta; C081021:Go 6976; D030421:Peroxynitrous Acid; D000242:Cyclic AMP; D037342:Pertussis Toxin; D051571:Protein Kinase C-alpha; D048051:p38 Mitogen-Activated Protein Kinases; D019206:GTP-Binding Protein alpha Subunits, Gi-Go; D000262:Adenylyl Cyclases; D007545:Isoproterenol