CLEC-2 expression is maintained on activated platelets and on platelet microparticles

Eelo Gitz, Alice Y Pollitt, Jerney J Gitz-Francois, Osama Alshehri, Jun Mori, Samantha Montague, Gerard B Nash, Michael R Douglas, Elizabeth E Gardiner, Robert K Andrews, Christopher D Buckley, Paul Harrison, Steve P Watson

Research output: Contribution to journalArticlepeer-review

69 Citations (Scopus)
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Abstract

The C-type lectin-like receptor CLEC-2 mediates platelet activation through a hem-immunoreceptor tyrosine-based activation motif (hemITAM). CLEC-2 initiates a Src- and Syk-dependent signaling cascade that is closely related to that of the 2 platelet ITAM receptors: glycoprotein (GP)VI and FcγRIIa. Activation of either of the ITAM receptors induces shedding of GPVI and proteolysis of the ITAM domain in FcγRIIa. In the present study, we generated monoclonal antibodies against human CLEC-2 and used these to measure CLEC-2 expression on resting and stimulated platelets and on other hematopoietic cells. We show that CLEC-2 is restricted to platelets with an average copy number of ∼2000 per cell and that activation of CLEC-2 induces proteolytic cleavage of GPVI and FcγRIIa but not of itself. We further show that CLEC-2 and GPVI are expressed on CD41+ microparticles in megakaryocyte cultures and in platelet-rich plasma, which are predominantly derived from megakaryocytes in healthy donors, whereas microparticles derived from activated platelets only express CLEC-2. Patients with rheumatoid arthritis, an inflammatory disease associated with increased microparticle production, had raised plasma levels of microparticles that expressed CLEC-2 but not GPVI. Thus, CLEC-2, unlike platelet ITAM receptors, is not regulated by proteolysis and can be used to monitor platelet-derived microparticles.

Original languageEnglish
Pages (from-to)2262-70
Number of pages9
JournalBlood
Volume124
Issue number14
DOIs
Publication statusPublished - 2 Oct 2014

Keywords

  • Animals
  • Antibodies, Monoclonal
  • Arthritis, Rheumatoid
  • Blood Platelets
  • Humans
  • Inflammation
  • Lectins, C-Type
  • Megakaryocytes
  • Membrane Glycoproteins
  • Mice
  • Platelet Activation
  • Platelet Membrane Glycoprotein IIb
  • Platelet Membrane Glycoproteins
  • Receptors, IgG
  • Recombinant Proteins

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