Actin reorganization in airway smooth muscle cells involves Gq and Gi-2 activation of Rho.
Extracellular stimuli induce cytoskeleton reorganization (stress-fiber formation) in cells and Ca2+ sensitization in intact smooth muscle preparations by activating signaling pathways that involve Rho proteins, a subfamily of the Ras superfamily of monomeric G proteins. In airway smooth muscle, the agonists responsible for cytoskeletal reorganization via actin polymerization are poorly understood. Carbachol-, lysophosphatidic acid (LPA)-, and endothelin-1-induced increases in filamentous actin staining are indicative of actin reorganization (filamentous-to-globular actin ratios of 2.4 +/- 0.3 in control cells, 6.7 +/- 0.8 with carbachol, 7.2 +/- 0.8 with LPA, and 7.4 +/- 0.9 with endothelin-1; P < 0.001; n = 14 experiments). Although the effect of all agonists was blocked by C3 exoenzyme (inactivator of Rho), only carbachol was blocked by pertussis toxin. Although carbachol-induced actin reorganization was blocked in cells pretreated with antisense oligonucleotides directed against Galphai-2 alone, LPA- and endothelin-1-induced actin reorganization were only blocked when both Galphai-2 and G(q)alpha were depleted. These data indicate that in human airway smooth muscle cells, carbachol induces actin reorganization via a Galphai-2 pathway, whereas LPA or endothelin-1 induce actin reorganization via either a Galphai-2 or a Gqalpha pathway.
Hirshman
C A
CA
Department of Anesthesiology, College of Physicians and Surgeons of Columbia University, New York, New York 10032, USA.
Emala
C W
CW
D036002:ADP Ribose Transferases / Q000494:pharmacology; D000199:Actins / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D001905:Botulinum Toxins; D002217:Carbachol / Q000037:antagonists & inhibitors / Q000494:pharmacology; D019332:Endothelin-1 / Q000037:antagonists & inhibitors / Q000494:pharmacology; D019204:GTP-Binding Proteins / Q000235:genetics / Q000502:physiology*; D006801:Humans; D008246:Lysophospholipids / Q000037:antagonists & inhibitors / Q000494:pharmacology; D009130:Muscle, Smooth / Q000166:cytology / Q000378:metabolism*; D016376:Oligonucleotides, Antisense / Q000494:pharmacology; D037342:Pertussis Toxin; D014132:Trachea / Q000166:cytology / Q000378:metabolism*; D010566:Virulence Factors, Bordetella / Q000494:pharmacology; D018631:ras Proteins / Q000502:physiology*
D000199:Actins; D019332:Endothelin-1; D008246:Lysophospholipids; D016376:Oligonucleotides, Antisense; D010566:Virulence Factors, Bordetella; D002217:Carbachol; D036002:ADP Ribose Transferases; C063007:exoenzyme C3, Clostridium botulinum; D037342:Pertussis Toxin; D001905:Botulinum Toxins; D019204:GTP-Binding Proteins; D018631:ras Proteins