Lipid Products of Phosphoinositide 3-Kinase and Phosphatidylinositol 4,5-Bisphosphate Are Both Required for ADP-dependent Platelet Spreading*

Jean-Michel Heraud (1) , Claire Racaud-Sultan (1) , Daisy Gironcel (1) , Corinne Albigès-Rizo (2) , Thierry Giacomini (3) , Séverine Roques (1) , Véronique Martel (4, 2) , Monique Breton-Douillon (1) , Bertrand Perret (1) , Hugues Chap (1)

1 INSERM - Institut National de la Santé et de la Recherche Médicale
2 LEDAC - Laboratoire d'études de la différenciation et de l'adhérence cellulaires
3 SUPAERO - École nationale supérieure de l'aéronautique et de l'espace
4 Institut Albert Bonniot

We have shown previously that ADP released upon platelet adhesion mediated by IIb 3 integrin triggers accumulation of phosphatidylinositol 3,4-bisphosphate (PtdIns-3,4-P 2) (Gironcel, D., Racaud-Sultan, C., Payras-tre, 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-ki-nase 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-P 2 synthesis was totally inhibited (25 M 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 inhibi-tors on platelet spreading. Although synthetic dipalmi-toyl PtdIns-3,4-P 2 and dipalmitoyl phosphatidylinositol 3,4,5-trisphosphate restored only partially platelet spreading, phosphatidylinositol 4,5-bisphosphate (Pt-dIns-4,5-P 2) was able to trigger full spreading of wort-mannin-treated adherent platelets. Following 32 P labeling of intact platelets, the recovery of [ 32 P]PtdIns-4,5-P 2 in anti-talin immunoprecipitates from adherent plate-lets was found to be decreased upon treatment by wort-mannin. 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-P 2 could be a downstream messenger of this signaling pathway.

Domains: Santé publique et épidémiologie; Infectious diseases; Emerging diseases; Molecular biology; Virology

Jean-Michel Heraud, Claire Racaud-Sultan, Daisy Gironcel, Corinne Albigès-Rizo, Thierry Giacomini, et al.. Lipid Products of Phosphoinositide 3-Kinase and Phosphatidylinositol 4,5-Bisphosphate Are Both Required for ADP-dependent Platelet Spreading*. Journal of Biological Chemistry, 1998, 273 (28), pp.17817-23. ⟨10.1074/jbc.273.28.17817⟩. ⟨pasteur-01676555⟩