Src family tyrosine kinase Lyn mediates VWF GPIb-IX induced platelet activation via the cGMP signaling pathway

Hong Yin, Junling Liu, Zhenyu Li, Michael C. Berndt, Clifford A. Lowell, Xiaoping Du

Research output: Contribution to journalArticlepeer-review

88 Scopus citations

Abstract

The platelet receptor for von Willebrand factor (VWF), glycoprotein (GP) Ib-IX, mediates initial platelet adhesion and transmits signals leading to platelet activation. Src family tyrosine kinases (SFKs) play an important role in VWF-induced GPIb-IX signaling. However, the SFK-dependent downstream signaling pathway is unclear but is thought to involve thromboxane A2 (TXA2) synthesis. Here we show that, although platelets deficient in SFK members, Lyn or Fyn, were defective in the TXA2-dependent second wave of platelet aggregation induced by botrocetin/VWF. only Lyn-knockout platelets were also defective in stable platelet adhesion to VWF under shear stress that is independent of the TXA2 pathway. Lyn-knockout platelets also spread poorly on VWF but spread normally on fibrinogen, indicating an important role for Lyn in VWF-mediated GPIb signaling but not in inte-grin outside-in signaling. Importantly, Lyn knockout abrogated VWF-induced cGMP elevation. Addition of low concentrations of 8-bromo-cGMP, however, corrected the defective stable adhesion of Lyn-knockout platelets or PP2-treated platelets on VWF. These results demonstrate an important role for Lyn in VWF/GPIb-IX-induced integrin activation mediated via the cGMP signaling pathway independently of TXA2 synthesis and also indicate that Lyn is critically important in GPIb-IX-mediated activation of the cGMP pathway.

Original languageEnglish
Pages (from-to)1139-1146
Number of pages8
JournalBlood
Volume112
Issue number4
DOIs
StatePublished - Aug 15 2008

ASJC Scopus subject areas

  • Biochemistry
  • Immunology
  • Hematology
  • Cell Biology

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