A role for glycosphingolipid-enriched microdomains in platelet glycoprotein Ib-mediated platelet activation

W. Jin, O. Inoue, N. Tamura, K. Suzuki-inoue, K. Satoh, M. C. Berndt, M. Handa, S. Goto, Yukio Ozaki

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Abstract

Background: Glycoprotein (GP) Ib, a platelet von Willebrand factor (VWF) receptor, plays a crucial role in thrombosis and hemostasis. As recent reports have suggested that GPIb partially locates in a particular region, designated as glycosphingolipid-enriched microdomains (GEMs), we hypothesized that GEMs play a central role in GPIb-mediated platelet activation. Methods: Platelets were stimulated by VWF/botrocetin to activate platelets through GPIb. GEMs and non-GEMs were isolated by sucrose density gradient ultracentrifugation and the location of signaling molecules characterized. The role of GEMs-mediated signaling in platelet behavior was tested by platelet aggregation and by platelet interaction with immobilized VWF under flow conditions when GEMs were disrupted by methyl-β-cyclodextrin (MβCD). Results: GPIb was partially translocated to GEMs upon VWF/botrocetin stimulation. Immunoprecipitation of GPIb in GEMs and non-GEMs revealed that the tyrosine kinases, Src and Lyn, were associated with GPIb only in GEMs after GPIb-stimulation, and not in non-GEMs. Activation of PLCγ2 was more intense in GEMs than non-GEMs. Disruption of GEMs by MβCD strongly inhibited tyrosine phosphorylation of Syk and PLCγ2. Functional studies revealed that stable adhesion of platelets to a VWF-coated surface under flow was impaired by GEM disruption by MβCD. Conclusion: The combined results suggest that GEMs play an important role in GPIb-mediated platelet activation.

Original languageEnglish
Pages (from-to)1034-1040
Number of pages7
JournalJournal of Thrombosis and Haemostasis
Volume5
Issue number5
DOIs
Publication statusPublished - 2007 May 1

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Keywords

  • GEMs
  • GPIb
  • Lyn
  • Src

ASJC Scopus subject areas

  • Hematology

Cite this

Jin, W., Inoue, O., Tamura, N., Suzuki-inoue, K., Satoh, K., Berndt, M. C., Handa, M., Goto, S., & Ozaki, Y. (2007). A role for glycosphingolipid-enriched microdomains in platelet glycoprotein Ib-mediated platelet activation. Journal of Thrombosis and Haemostasis, 5(5), 1034-1040. https://doi.org/10.1111/j.1538-7836.2007.02476.x