Activation of signal transduction in platelets by the tyrosine phosphatase inhibitor pervanadate (vanadyl hydroperoxide).
The protein tyrosine phosphatase (PTPase) inhibitor pervanadate (vanadyl hydroperoxide) stimulated protein tyrosine phosphorylation 29-fold more than did thrombin in intact and saponin-permeabilized platelets. Increased tyrosine phosphorylation preceded, or was coincident with, a fall in PtdIns(4,5)P2 levels, production of PtdIns(3,4)P2 and phosphatidic acid, mobilization of intracellular Ca2+, stimulation of protein kinase C-dependent protein phosphorylation, secretion of dense and alpha-granules, increased actin polymerization, shape change and aggregation which required fibrinogen and was mediated by increased surface expression of GPIIb-IIIa. The tyrosine kinase inhibitor RG 50864 totally prevented induction of tyrosine phosphorylation by pervanadate, as well as all other responses measured; in contrast, the inactive structural analogue, tyrphostin #1, had no effect. Dense-granule secretion induced by pervanadate required protein kinase C activity; however, aggregation and alpha-granule secretion were independent of protein kinase C. In saponin-permeabilized platelets pervanadate and thrombin stimulated phospholipase C activity by GTP-independent and GTP-dependent mechanisms respectively. We conclude that PTPases are important regulators of signal transduction in platelets.
Pumiglia
K M
KM
Department of Pharmacology, University of Connecticut Health Center, Farmington 06030.
Lau
L F
LF
Huang
C K
CK
Burroughs
S
S
Feinstein
M B
MB
D000199:Actins / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000470:Alkaloids / Q000494:pharmacology; D001798:Blood Proteins / Q000378:metabolism; D015153:Blotting, Western; D002118:Calcium / Q000378:metabolism; D002396:Catechols / Q000494:pharmacology; D002478:Cells, Cultured; D004591:Electrophoresis, Polyacrylamide Gel; D004789:Enzyme Activation; D006801:Humans; D009570:Nitriles / Q000494:pharmacology; D010743:Phospholipids / Q000378:metabolism; D010750:Phosphoproteins; D010766:Phosphorylation; D010980:Platelet Membrane Glycoproteins / Q000378:metabolism; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism; D017027:Protein Tyrosine Phosphatases / Q000037:antagonists & inhibitors*; D012701:Serotonin / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*; D019311:Staurosporine; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D010738:Type C Phospholipases / Q000378:metabolism; D014443:Tyrosine / Q000378:metabolism; D020032:Tyrphostins; D014638:Vanadates / Q000494:pharmacology*
D000199:Actins; D000470:Alkaloids; D001798:Blood Proteins; D002396:Catechols; D009570:Nitriles; D010743:Phospholipids; D010750:Phosphoproteins; D010980:Platelet Membrane Glycoproteins; D020032:Tyrphostins; C076715:pervanadate; C039077:platelet protein P47; C060152:tyrphostin 47; D012701:Serotonin; D014638:Vanadates; D014443:Tyrosine; D000255:Adenosine Triphosphate; D011493:Protein Kinase C; D017027:Protein Tyrosine Phosphatases; D010738:Type C Phospholipases; D019311:Staurosporine; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium