Platelet-derived-growth-factor-induced signalling in human platelets: phosphoinositide-3-kinase-dependent inhibition of platelet activation
| Autor: | Miriam H. Fukami, Frode Selheim, Holm Holmsen, Flemming S. Vassbotn |
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| Rok vydání: | 2000 |
| Předmět: | |
| Zdroj: | Biochemical Journal. 350:469-475 |
| ISSN: | 1470-8728 0264-6021 |
| DOI: | 10.1042/bj3500469 |
| Popis: | Human platelets release platelet-derived growth factor (PDGF) from α-granules during platelet activation. We have previously shown that platelets have PDGF α-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)P2 and PtdIns(3,4,5)P3 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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