title: Isoproterenol induces actin depolymerization in human airway smooth muscle cells via activation of an Src kinase and GS.
abstract: In a previous study, we showed that isoproterenol induced actin depolymerization in human airway smooth muscle cells by both protein kinase A (PKA)-dependent and -independent signaling pathways. We now investigate the signaling pathway of PKA-independent actin depolymerization induced by isoproterenol in these cells. Cells were briefly exposed to isoproterenol or PGE(1) in the presence and absence of specific inhibitors of Src-family tyrosine kinases, phosphatidylinositol-3-kinase (PI3 kinase), or MAP kinase, and actin depolymerization was measured by concomitant staining of filamentous actin with FITC-phalloidin and globular actin with Texas red DNase I. Isoproterenol, cholera toxin, and PGE(1) induced actin depolymerization, indicated by a decrease in the intensity of filamentous/globular fluorescent staining. Pretreatment with the Src kinase inhibitors 4-amino-5-(4-chlorophenyl)-7-(t-butyl)pyrazolo[3,4-d]pyriimidine (PP2) or geldanamycin or the PKA inhibitor Rp-cAMPS only partly inhibited isoproterenol- or PGE(1)-induced actin depolymerization. In contrast, PP2 and geldanamycin did not inhibit forskolin-induced actin depolymerization, and AG-213 (an EGF receptor tyrosine kinase inhibitor) did not inhibit isoproterenol- or PGE(1)-induced actin depolymerization. PI3 kinase or MAP kinase inhibition did not inhibit isoproterenol-induced actin depolymerization. Moreover, isoproterenol but not forskolin induced tyrosine phosphorylation of an Src family member at position 416. These results further confirm that both PKA-dependent and PKA-independent pathways mediate actin depolymerization in human airway smooth muscle cells and that the PKA-independent pathway by which isoproterenol induces actin depolymerization in human airway smooth muscle cells involves Src protein tyrosine kinases and the G(s) protein.
authors.affiliation: Dept of Anesthesiology, College of Physicians and Surgeons of Columbia University, New York, New York 10032, USA. cah63@columbia.edu
authors.forename: Carol A
authors.initials: CA
authors.lastname: Hirshman
authors.forename: Defen
authors.initials: D
authors.lastname: Zhu
authors.forename: Thomas
authors.initials: T
authors.lastname: Pertel
authors.forename: Reynold A
authors.initials: RA
authors.lastname: Panettieri
authors.forename: Charles W
authors.initials: CW
authors.lastname: Emala
mesh_terms: D000276:Adjuvants, Immunologic / Q000494:pharmacology; D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D016227:Benzoquinones; D002478:Cells, Cultured; D002772:Cholera Toxin / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D019205:GTP-Binding Protein alpha Subunits, Gs / Q000378:metabolism*; D006801:Humans; D007545:Isoproterenol / Q000494:pharmacology*; D047029:Lactams, Macrocyclic; D032389:Myocytes, Smooth Muscle / Q000187:drug effects* / Q000378:metabolism; D010766:Phosphorylation; D011809:Quinones / Q000494:pharmacology; D014132:Trachea / Q000166:cytology*; D014443:Tyrosine / Q000378:metabolism; D019061:src-Family Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*
chemical_list: D000276:Adjuvants, Immunologic; D000318:Adrenergic beta-Agonists; D016227:Benzoquinones; D004791:Enzyme Inhibitors; D047029:Lactams, Macrocyclic; D011809:Quinones; D014443:Tyrosine; D002772:Cholera Toxin; D019061:src-Family Kinases; D019205:GTP-Binding Protein alpha Subunits, Gs; D007545:Isoproterenol; C001277:geldanamycin