Lipid products of phosphoinositide 3-kinase and phosphatidylinositol 4',5'-bisphosphate are both required for ADP-dependent platelet spreading

• Published in: The Journal of biological chemistry Vol. 273; no. 28; pp. 17817 - 17823
• Main Authors: Heraud, J M, Racaud-Sultan, C, Gironcel, D, Albigès-Rizo, C, Giacomini, T, Roques, S, Martel, V, Breton-Douillon, M, Perret, B, Chap, H
• Format: Journal Article
• Language: English
• Published: United States American Society for Biochemistry and Molecular Biology 10.07.1998
• Subjects: Adenosine Diphosphate; Adenosine Diphosphate - pharmacology; Androstadienes; Androstadienes - pharmacology; Biochemistry, Molecular Biology; Blood Platelets; Blood Platelets - cytology; Blood Platelets - drug effects; Blood Platelets - metabolism; Cell Adhesion; Cell Adhesion - drug effects; Chromones; Chromones - pharmacology; Emerging diseases; Enzyme Activation; Enzyme Inhibitors; Enzyme Inhibitors - pharmacology; Human health and pathology; Humans; Indoles; Indoles - pharmacology; Infectious diseases; Life Sciences; Maleimides; Maleimides - pharmacology; Microbiology and Parasitology; Molecular biology; Morpholines; Morpholines - pharmacology; Phosphatidylinositol 3-Kinases; Phosphatidylinositol 3-Kinases - metabolism; Phosphatidylinositol 4,5-Diphosphate; Phosphatidylinositol 4,5-Diphosphate - metabolism; Phosphatidylinositols; Phosphatidylinositols - metabolism; Phosphoinositide-3 Kinase Inhibitors; Santé publique et épidémiologie; Signal Transduction; Talin; Talin - metabolism; Virology; Wortmannin
• DOI: 10.1074/jbc.273.28.17817
• ISSN: 0021-9258

We have shown previously that ADP released upon platelet adhesion mediated by alphaIIb beta3 integrin triggers accumulation of phosphatidylinositol 3',4'-bisphosphate (PtdIns-3,4-P2) (Gironcel, D. , Racaud-Sultan, C., Payrastre, B., Haricot, M., Borchert, G., Kieffer, N., Breton, M., and Chap, H. (1996) FEBS Lett. 389, 253-256). ADP has also been involved in platelet spreading. Therefore, in order to study a possible role of phosphoinositide 3-kinase in platelet morphological changes following adhesion, human platelets were pretreated with specific phosphoinositide 3-kinase inhibitors LY294002 and wortmannin. Under conditions where PtdIns-3, 4-P2 synthesis was totally inhibited (25 microM LY294002 or 100 nM wortmannin), platelets adhered to the fibrinogen matrix, extended pseudopodia, but did not spread. Moreover, addition of ADP to the medium did not reverse the inhibitory effects of phosphoinositide 3-kinase inhibitors on platelet spreading. Although synthetic dipalmitoyl PtdIns-3,4-P2 and dipalmitoyl phosphatidylinositol 3',4', 5'-trisphosphate restored only partially platelet spreading, phosphatidylinositol 4',5'-bisphosphate (PtdIns-4,5-P2) was able to trigger full spreading of wortmannin-treated adherent platelets. Following 32P labeling of intact platelets, the recovery of [32P]PtdIns-4,5-P2 in anti-talin immunoprecipitates from adherent platelets was found to be decreased upon treatment by wortmannin. These results suggest that the lipid products of phosphoinositide 3-kinase are required but not sufficient for ADP-induced spreading of adherent platelets and that PtdIns-4,5-P2 could be a downstream messenger of this signaling pathway.