Phosphorylation of CLEC-2 is dependent on lipid rafts, actin polymerization, secondary mediators, and Rac

Research output: Contribution to journalArticlepeer-review

Authors

  • Beata Grygielska
  • B Leblond
  • L Desire
  • JA Eble

Colleges, School and Institutes

Abstract

The C-type lectin-like receptor 2 (CLEC-2)activates platelets through Src and Syk tyrosine kinases via a single cytoplasmic YxxL motif known as a hem immunoreceptor tyrosine-based activation motif (hemITAM).Here, we demonstrate using sucrose gradient ultracentrifugation and methyl--cyclodextrin treatment that CLEC-2 translocates to lipid rafts upon ligand engagement and that translocation is essential for hemITAM phosphorylation and signal initiation. HemITAM phosphorylation, but not translocation, is also critically dependent on actin polymerization,Rac1 activation, and release of ADP and thromboxane A2 (TxA2). The role of ADP and TxA2 in mediating hosphorylation is dependent on ligand engagement and rac activation but is independent of platelet aggregation. In contrast,tyrosine phosphorylation of the GPVIFcR -chain ITAM, which has 2 YxxL motifs,is independent of actin polymerization and secondary mediators. These results reveal a unique series of proximal events in CLEC-2 phosphorylation involving actin polymerization, secondary mediators,and Rac activation.

Details

Original languageEnglish
Pages (from-to)2938-2946
Number of pages9
JournalBlood
Volume115
Issue number14
Publication statusPublished - 1 Apr 2010