Gialpha but not gqalpha is linked to activation of p21(ras) in human airway smooth muscle cells.
Airway smooth muscle hypertrophy contributes to the narrowing of asthmatic airways. Activation of the mitogen-activated protein kinases is an important event in mediating cell proliferation. Because the monomeric G protein p21(ras) is an important intermediate leading to activation of mitogen-activated protein kinases, we questioned which heterotrimeric G protein-coupled receptors were linked to the activation of p21(ras) in cultured human airway smooth muscle and which of the heterotrimeric G protein subunits (alpha or betagamma) transmitted the activation signal. Carbachol and endothelin-1 increased GTP-bound p21(ras) in a pertussis toxin-sensitive manner [ratio of [32P]GTP to ([32P]GTP + [32P]GDP): control, 30 +/- 1.7; 3 min of 1 microM carbachol, 39 +/- 1.1; 3 min of 1 microM endothelin-1, 40 +/- 1.2], whereas histamine, bradykinin, and KCl were without effect. Transfection of an inhibitor of the G protein betagamma-subunit [the carboxy terminus (Gly495-Leu689) of the beta-adrenoceptor kinase 1] failed to inhibit the carbachol-induced activation of p21(ras). These data suggest that Gi- but not Gq-coupled receptors activate p21(ras) in human airway smooth muscle cells, and this effect most likely involves the alpha-subunit.
Emala
C W
CW
Department of Anesthesiology, Columbia University College of Physicians and Surgeons, New York, New York 10032, USA.
Liu
F
F
Hirshman
C A
CA
D001920:Bradykinin / Q000494:pharmacology; D002217:Carbachol / Q000494:pharmacology; D002478:Cells, Cultured; D017868:Cyclic AMP-Dependent Protein Kinases / Q000235:genetics / Q000378:metabolism; D019332:Endothelin-1 / Q000494:pharmacology; D019204:GTP-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D006153:Guanosine Diphosphate / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism; D006632:Histamine / Q000494:pharmacology; D006801:Humans; D009130:Muscle, Smooth / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D010446:Peptide Fragments / Q000235:genetics / Q000378:metabolism; D037342:Pertussis Toxin; D011189:Potassium Chloride / Q000494:pharmacology; D016283:Proto-Oncogene Proteins p21(ras) / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D014132:Trachea / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D014162:Transfection; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D019332:Endothelin-1; D010446:Peptide Fragments; D011994:Recombinant Proteins; D010566:Virulence Factors, Bordetella; D006153:Guanosine Diphosphate; D011189:Potassium Chloride; D006632:Histamine; D006160:Guanosine Triphosphate; D002217:Carbachol; D037342:Pertussis Toxin; D017868:Cyclic AMP-Dependent Protein Kinases; C114043:BARKct protein, recombinant; D019204:GTP-Binding Proteins; C501009:HRAS protein, human; D016283:Proto-Oncogene Proteins p21(ras); D001920:Bradykinin