Sphingosylphosphorylcholine stimulates mitogen-activated protein kinase via a Ca2+-dependent pathway.
In cultured porcine aortic smooth muscle cells, sphingosylphosphorylcholine (SPC), ATP, or bradykinin (BK) induced a rapid dose-dependent increase in the cytosolic Ca2+ concentration ([Ca2+]i) and also stimulated inositol 1,4,5-trisphosphate (IP3) generation. Pretreatment of cells with pertussis toxin blocked the SPC-induced IP3 generation and [Ca2+]i increase but had no effect on the action of ATP or BK. In addition, SPC stimulated the mitogen-activated protein kinase (MAPK) and increased DNA synthesis, whereas neither ATP nor BK produced such effects. Both the SPC-induced MAPK activation and DNA synthesis were pertussis toxin sensitive. SPC-induced MAPK activation was blocked by treatment of cells with the phospholipase C inhibitor, U-73122, or the intracellular Ca2+-ATPase inhibitor, thapsigargin, but not by removal of extracellular Ca2+. Lysophosphatidic acid induced cellular responses similar to SPC in a pertussis toxin-sensitive manner in terms of [Ca2+]i increase, IP3 generation, MAPK activation, and DNA synthesis. Platelet-derived growth factor (PDGF) also induced a [Ca2+]i increase, MAPK activation, and DNA synthesis in the same cells; however, the PDGF-induced MAPK activation was not sensitive to pertussis toxin and changes in [Ca2+]i. SPC-induced MAPK activation was inhibited by pretreatment of cells with staurosporine, W-7, or calmidazolium. Our results suggest that, in porcine aortic smooth muscle cells, MAPK is not activated by the increase in [Ca2+]i unless a pertussis toxin-sensitive G protein is simultaneously stimulated, indicating the role of Ca2+ in pertussis toxin-sensitive G protein-mediated MAPK activation.
Chin
T Y
TY
Department of Biochemistry, National Defense Medical Center, Taipei, Taiwan, Republic of China.
Chueh
S H
SH
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D001011:Aorta / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D001920:Bradykinin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors; D002478:Cells, Cultured; D003600:Cytosol / Q000378:metabolism; D004247:DNA / Q000096:biosynthesis; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004963:Estrenes / Q000494:pharmacology; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism; D007700:Kinetics; D008246:Lysophospholipids / Q000494:pharmacology; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D037342:Pertussis Toxin; D010767:Phosphorylcholine / Q000031:analogs & derivatives* / Q000494:pharmacology; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D011760:Pyrrolidinones / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000494:pharmacology; D019311:Staurosporine / Q000494:pharmacology; D013552:Swine; D019284:Thapsigargin / Q000494:pharmacology; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D004791:Enzyme Inhibitors; D004963:Estrenes; D008246:Lysophospholipids; D010982:Platelet-Derived Growth Factor; D011760:Pyrrolidinones; D010566:Virulence Factors, Bordetella; C005356:sphingosine phosphorylcholine; D010767:Phosphorylcholine; C060229:1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione; D019284:Thapsigargin; D015544:Inositol 1,4,5-Trisphosphate; D000255:Adenosine Triphosphate; D004247:DNA; D037342:Pertussis Toxin; D011493:Protein Kinase C; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D000252:Calcium-Transporting ATPases; D019311:Staurosporine; D013110:Sphingosine; D001920:Bradykinin; D002118:Calcium