Thromb Haemost 2003; 89(02): 318-330
DOI: 10.1055/s-0037-1613449
Platelets and Blood Cells
Schattauer GmbH

A critical role of lipid rafts in the organization of a key FcγRIIa-mediated signaling pathway in human platelets

Autoren

  • Stéphane Bodin

    1   Inserm, Unité 563, Centre de Physiopathologie de Toulouse Purpan, Department of Oncogenesis and Signaling in Haematopoïetic Cells, IFR30, Hôpital Purpan, Toulouse, France
  • Cécile Viala

    1   Inserm, Unité 563, Centre de Physiopathologie de Toulouse Purpan, Department of Oncogenesis and Signaling in Haematopoïetic Cells, IFR30, Hôpital Purpan, Toulouse, France
  • Ashraf Ragab

    1   Inserm, Unité 563, Centre de Physiopathologie de Toulouse Purpan, Department of Oncogenesis and Signaling in Haematopoïetic Cells, IFR30, Hôpital Purpan, Toulouse, France
  • Bernard Payrastre

    1   Inserm, Unité 563, Centre de Physiopathologie de Toulouse Purpan, Department of Oncogenesis and Signaling in Haematopoïetic Cells, IFR30, Hôpital Purpan, Toulouse, France
Weitere Informationen

Publikationsverlauf

Received 20. Mai 2002

Accepted after resubmission 25. Oktober 2002

Publikationsdatum:
07. Dezember 2017 (online)

Summary

The involvement of platelet FcγRIIa in heparin-associated thrombocytopenia (HIT) is now well established. However, the precise sequence of molecular events initiated by FcγRIIa cross-linking in platelets remains partly characterized. We investigated here the role of lipid rafts in the spatio-temporal organization of the FcγRIIa-dependent signaling events. Upon cross-linking, FcγRIIa relocated in rafts where the kinase Lyn and the adapter LAT were among the major phosphotyrosyl proteins. Upon stimulation by HIT sera, the second messenger phosphatidylinositol 3,4,5-trisphosphate (PtdIns(3,4,5)P3) accumulated in rafts in a P2Y12 adenosine diphosphate (ADP) recep- tor-dependent manner. PtdIns(3,4,5)P3 was then essential to specifically recruit phospholipase Cγ2 (PLCγ2) to these membrane microdomains. Controlled disruption of rafts by methyl γ-cyclodextrin reversibly abolished PtdIns(3,4,5)P3 production, PLC activation and platelet responses induced by FcγRIIa cross-linking without affecting the tyrosine phosphorylation events. This work demonstrates that platelet rafts are essential for the integration of a key signaling complex leading to the rapid production of PtdIns(3,4,5)P3 and in turn PLCγ2 activation during HIT.