Thrombin activates MAPKAP2 kinase in vascular smooth muscle.
OBJECTIVE
Thrombin mediates hemostasis by promoting thrombus development and vasospasm, which reduces the size of the arterial injury. Thrombin stimulation of vascular smooth muscle is associated with activation of mitogen-associated protein kinase. The purpose of this investigation was to determine the subsequent cellular signaling events in thrombin-stimulated vascular smooth muscle contraction.


METHODS
Contractile responses of bovine carotid artery smooth muscle were determined in a muscle bath and compared with phosphorylation events with two-dimensional gel electrophoresis. The activity of a novel kinase, mitogen-activated protein kinase-activated protein-2 kinase (MAPKAP2 kinase), was determined by immunoprecipitation and a phosphotransferase assay. A small heat shock protein, HSP27, was identified with immunoblotting.


RESULTS
Thrombin induces contraction of vascular smooth muscle and is associated with increased activity of MAPKAP2 kinase and increased phosphorylation of HSP27. Multiple isoforms of HSP27 are the predominant phosphoproteins in vascular smooth muscle, and peptide mapping suggests that the isoforms of HSP27 are structurally related and phosphorylated within similar peptide sequences.


CONCLUSIONS
Activation of the MAPKAP2 kinase pathway and phosphorylation of HSP27 are associated with thrombin-induced contraction of vascular smooth muscle.
Brophy
C M
CM
Department of Surgery, Medical College of Georgia, and Augusta Veterans Administration Medical Center, USA.
Woodrum
D
D
Dickinson
M
M
Beall
A
A
D000818:Animals; D001158:Arteries / Q000293:injuries / Q000503:physiopathology; D001777:Blood Coagulation / Q000502:physiology; D002339:Carotid Arteries / Q000187:drug effects / Q000201:enzymology; D002417:Cattle; D015180:Electrophoresis, Gel, Two-Dimensional; D004789:Enzyme Activation; D006360:Heat-Shock Proteins / Q000032:analysis / Q000187:drug effects / Q000378:metabolism; D006706:Homeostasis / Q000502:physiology; D015151:Immunoblotting; D047908:Intracellular Signaling Peptides and Proteins; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000201:enzymology*; D010449:Peptide Mapping; D010750:Phosphoproteins / Q000032:analysis / Q000187:drug effects / Q000378:metabolism; D010766:Phosphorylation; D010770:Phosphotransferases / Q000032:analysis; D011233:Precipitin Tests; D017346:Protein Serine-Threonine Kinases / Q000187:drug effects* / Q000378:metabolism; D017421:Sequence Analysis; D015398:Signal Transduction / Q000502:physiology; D013917:Thrombin / Q000494:pharmacology* / Q000502:physiology; D014661:Vasoconstriction / Q000502:physiology; D000099190:MAP-Kinase-Activated Kinase 2
D006360:Heat-Shock Proteins; D047908:Intracellular Signaling Peptides and Proteins; D010750:Phosphoproteins; D010770:Phosphotransferases; D017346:Protein Serine-Threonine Kinases; D013917:Thrombin; D000099190:MAP-Kinase-Activated Kinase 2