A Mitogen-activated Protein Kinase-dependent Signaling Pathway in the Activation of Platelet Integrin αIIbβ3

Zhenyu Li, Xiaodong Xi, Xiaoping Du

Research output: Contribution to journalArticlepeer-review

111 Scopus citations

Abstract

We have recently shown that the platelet integrin αII/β 3 is activated by von Willebrand factor (vWF) binding to its platelet receptor, glycoprotein Ib-IX (GPIb-IX), via the protein kinase G (PKG) signaling pathway. Here we show that GPIb-IX-mediated activation of integrin αIIbβ3 is inhibited by dominant negative mutants of Raf-1 and MEK1 in a reconstituted integrin activation model in Chinese hamster ovary (CHO) cells and that the integrin-dependent platelet aggregation induced by either vWF or low dose thrombin is inhibited by MEK inhibitors PD98059 and U0126. Thus, mitogen-activated protein kinase (MAPK) pathway is important in GPIb-IX-dependent activation of platelet integrin αIIbβ3. Furthermore, vWF binding to GPIb-IX induces phosphorylation of Thr-202/ Tyr-204 of extracellular signal-regulated kinase 2 (ERK2). GPIb-IX-induced ERK2 phosphorylation is inhibited by PKG inhibitors and enhanced by overexpression of recombinant PKG. PKG activators also induce ERK phosphorylation, indicating that activation of MAPK pathway is downstream from PKG. Thus, our data delineate a novel integrin activation pathway in which ligand binding to GPIb-IX activates PKG that stimulates MAPK pathway, leading to integrin activation.

Original languageEnglish
Pages (from-to)42226-42232
Number of pages7
JournalJournal of Biological Chemistry
Volume276
Issue number45
DOIs
StatePublished - Nov 9 2001

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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