Platelet-derived-growth-factor-induced signalling in human platelets: phosphoinositide-3-kinase-dependent inhibition of platelet activation
| Autor: | F, Selheim, M H, Fukami, H, Holmsen, F S, Vassbotn |
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| Rok vydání: | 2000 |
| Předmět: |
Blood Platelets
Platelet-Derived Growth Factor Morpholines Immunoblotting Flow Cytometry Platelet Activation Recombinant Proteins Androstadienes Phosphatidylinositol 3-Kinases Phosphatidylinositol Phosphates Chromones Humans Tyrosine Collagen Enzyme Inhibitors Phosphorylation Wortmannin Chromatography High Pressure Liquid Signal Transduction Research Article |
| Zdroj: | The Biochemical journal. |
| ISSN: | 0264-6021 |
| Popis: | Human platelets release platelet-derived growth factor (PDGF) from alpha-granules during platelet activation. We have previously shown that platelets have PDGF alpha-receptors, a transmembrane tyrosine kinase that takes part in negative feedback regulation during platelet activation. Here we have described a study of PDGF-induced tyrosine phosphorylation of platelet substrates and phosphoinositide 3-kinase (PI-3K) activity in collagen-stimulated platelets. By immunoblotting with phosphotyrosine antibodies of collagen-activated platelets we found that PDGF increased the phosphorylation of several platelet substrates, e.g. pp140, pp120 and pp85. PDGF inhibited collagen-induced platelet activation in the presence of inhibitors of autocrine stimulation, thus blocking the pure collagen-induced signal transduction. PDGF enhanced the collagen-induced formation of PtdIns(3,4)P(2) and PtdIns(3,4,5)P(3) as measured by HPLC. Wortmannin and LY294002, two unrelated inhibitors of PI-3K, were used to investigate the role of PI-3K in PDGF-induced platelet signalling. Incubation of platelets with wortmannin and LY294002 blocked the formation of three phosphorylated inositides as well as the inhibitory effect of PDGF on collagen-induced platelet activation. We conclude that the inhibitory effect of PDGF on platelet activation is PI-3K dependent. This is the first demonstration of a negative regulatory function of 3-phosphorylated inositides in platelets. |
| Databáze: | OpenAIRE |
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