Carbachol-induced actin reorganization involves Gi activation of Rho in human airway smooth muscle cells.
To determine whether M2 muscarinic receptors are linked to the monomeric G protein Rho, we studied the effect of carbachol on actin reorganization (stress fiber formation) in cultured human airway smooth muscle cells that expressed mainly M2 muscarinic receptors by dual-fluorescence labeling of filamentous (F) and monomeric (G) actin. F-actin was labeled with FITC-labeled phalloidin, and G-actin was labeled with Texas Red-labeled DNase I. Carbachol stimulation induced stress fiber formation (increased F-actin staining) in the cells and increased the F- to G-actin ratio 3.6 +/- 0.4-fold (mean +/- SE; n = 5 experiments). Preincubation with pertussis toxin, Clostridium C3 exoenzyme, or tyrosine kinase inhibitors reduced the carbachol-induced increase in stress fiber formation and significantly decreased the F- to G-actin ratio, whereas a mitogen-activated protein kinase inhibitor, a phosphatidylinositol 3-kinase inhibitor, and a protein kinase C inhibitor were without effect. This study demonstrates that in cultured human airway smooth muscle cells, muscarinic-receptor activation induces stress fiber formation via a pathway involving a pertussis-sensitive G protein, Rho proteins, and tyrosine phosphorylation.
Togashi
H
H
Department of Anesthesiology, Johns Hopkins Medical Institutions, Baltimore, Maryland 21205, USA.
Emala
C W
CW
Hall
I P
IP
Hirshman
C A
CA
D036002:ADP Ribose Transferases / Q000494:pharmacology; D000199:Actins / Q000502:physiology*; D001905:Botulinum Toxins; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000502:physiology; D002217:Carbachol / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D002396:Catechols / Q000494:pharmacology; D002478:Cells, Cultured; D004791:Enzyme Inhibitors / Q000494:pharmacology; D019204:GTP-Binding Proteins / Q000502:physiology*; D019833:Genistein / Q000494:pharmacology; D006801:Humans; D018721:Muscarinic Agonists / Q000494:pharmacology*; D009130:Muscle, Smooth / Q000166:cytology / Q000502:physiology*; D009570:Nitriles / Q000494:pharmacology; D037342:Pertussis Toxin; D019869:Phosphatidylinositol 3-Kinases / Q000502:physiology; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000502:physiology; D014132:Trachea / Q000166:cytology / Q000502:physiology*; D020032:Tyrphostins; D010566:Virulence Factors, Bordetella / Q000494:pharmacology; D020741:rho GTP-Binding Proteins / Q000502:physiology*
D036002:ADP Ribose Transferases; D000199:Actins; D001905:Botulinum Toxins; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D002217:Carbachol; D002396:Catechols; D004791:Enzyme Inhibitors; D019204:GTP-Binding Proteins; D019833:Genistein; D018721:Muscarinic Agonists; D009570:Nitriles; D037342:Pertussis Toxin; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011493:Protein Kinase C; D020032:Tyrphostins; D010566:Virulence Factors, Bordetella; D020741:rho GTP-Binding Proteins; C063007:exoenzyme C3, Clostridium botulinum; C060641:tyrphostin A23