Possible involvement of protein-tyrosine kinases such as p72syk in the disc-sphere change response of porcine platelets.
We previously reported that p72syk, a non-receptor tyrosine kinase, was activated maximally at 10 s after thrombin or thromboxane A2 stimulation, even in platelets that were not allowed to aggregate [Taniguchi et al. (1993) J. Biol. Chem. 268, 2277-2279; Maeda et al. (1993) Biochem. Biophys. Res. Commun. 197, 62-67]. Then, the change in the shape of porcine platelets induced by the thromboxane A2 analogue, STA2, and the role of protein-tyrosine kinases including p72syk in this response were evaluated, using the shape-change parameter. We show that p72syk activation is correlated with the disc-sphere change in a time- and dose-dependent manner following stimulation by STA2. Tyrphostin B44, a potent protein-tyrosine kinase inhibitor, reduced the thromboxane A2-evoked p72syk activation and the disc-sphere change in a dose-dependent manner. Furthermore, the translocation of p72syk to the cytoskeleton-rich fraction and an increase in the tyrosine phosphorylation of an about 120 kDa protein were observed during the disc-sphere change induced by STA2. These lines of evidence suggest that the activation of protein-tyrosine kinases such as p72syk may be involved in the disc-sphere change response in thromboxane A2-stimulated porcine platelets.
D000818:Animals; D000906:Antibodies / Q000276:immunology; D001597:Benzylidene Compounds / Q000494:pharmacology; D001792:Blood Platelets / Q000166:cytology* / Q000201:enzymology; D048429:Cell Size / Q000187:drug effects; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004792:Enzyme Precursors / Q000037:antagonists & inhibitors / Q000276:immunology / Q000378:metabolism*; D015151:Immunoblotting; D047908:Intracellular Signaling Peptides and Proteins; D008855:Microscopy, Electron, Scanning; D009570:Nitriles / Q000494:pharmacology; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000276:immunology / Q000378:metabolism*; D013552:Swine; D000072377:Syk Kinase; D013928:Thromboxane A2 / Q000031:analogs & derivatives / Q000494:pharmacology; D014443:Tyrosine / Q000378:metabolism
D000906:Antibodies; D001597:Benzylidene Compounds; D004791:Enzyme Inhibitors; D004792:Enzyme Precursors; D047908:Intracellular Signaling Peptides and Proteins; D009570:Nitriles; D014443:Tyrosine; D013928:Thromboxane A2; C037866:STA 2; C049855:ONO 3708; D011505:Protein-Tyrosine Kinases; D000072377:Syk Kinase