Platelet endothelial cell adhesion molecule-1 regulates collagen-stimulated platelet function by modulating the association of phosphatidylinositol 3-kinase with Grb-2-associated binding protein-1 and linker for activation of T cells

J Thromb Haemost. 2010 Nov;8(11):2530-41. doi: 10.1111/j.1538-7836.2010.04025.x.

Abstract

Background: Platelet activation by collagen depends on signals transduced by the glycoprotein (GP)VI-Fc receptor (FcR)γ-chain collagen receptor complex, which involves recruitment of phosphatidylinositol 3-kinase (PI3K) to phosphorylated tyrosines in the linker for activation of T cells (LAT). An interaction between the p85 regulatory subunit of PI3K and the scaffolding molecule Grb-2-associated binding protein-1 (Gab1), which is regulated by binding of the Src homology 2 domain-containing protein tyrosine phosphatase-2 (SHP-2) to Gab1, has been shown in other cell types to sustain PI3K activity to elicit cellular responses. Platelet endothelial cell adhesion molecule-1 (PECAM-1) functions as a negative regulator of platelet reactivity and thrombosis, at least in part by inhibiting GPVI-FcRγ-chain signaling via recruitment of SHP-2 to phosphorylated immunoreceptor tyrosine-based inhibitory motifs in PECAM-1.

Objective: To investigate the possibility that PECAM-1 regulates the formation of the Gab1-p85 signaling complexes, and the potential effect of such interactions on GPVI-mediated platelet activation in platelets.

Methods: The ability of PECAM-1 signaling to modulate the LAT signalosome was investigated with immunoblotting assays on human platelets and knockout mouse platelets.

Results: PECAM-1-associated SHP-2 in collagen-stimulated platelets binds to p85, which results in diminished levels of association with both Gab1 and LAT and reduced collagen-stimulated PI3K signaling. We therefore propose that PECAM-1-mediated inhibition of GPVI-dependent platelet responses result, at least in part, from recruitment of SHP-2-p85 complexes to tyrosine-phosphorylated PECAM-1, which diminishes the association of PI3K with activatory signaling molecules, such as Gab1 and LAT.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptor Proteins, Signal Transducing / metabolism
  • Animals
  • Blood Platelets / cytology
  • Blood Platelets / metabolism*
  • Class Ia Phosphatidylinositol 3-Kinase / metabolism
  • Collagen / metabolism*
  • GRB2 Adaptor Protein / metabolism*
  • Humans
  • Membrane Proteins / metabolism
  • Mice
  • Phosphatidylinositol 3-Kinases / metabolism*
  • Phosphoproteins / metabolism
  • Phosphorylation
  • Platelet Activation
  • Platelet Endothelial Cell Adhesion Molecule-1 / metabolism*
  • Platelet Membrane Glycoproteins / metabolism
  • Protein Tyrosine Phosphatase, Non-Receptor Type 11 / metabolism
  • Signal Transduction
  • Tyrosine / chemistry

Substances

  • Adaptor Proteins, Signal Transducing
  • GAB1 protein, human
  • GRB2 Adaptor Protein
  • Gab1 protein, mouse
  • LAT protein, human
  • Lat protein, mouse
  • Membrane Proteins
  • Phosphoproteins
  • Platelet Endothelial Cell Adhesion Molecule-1
  • Platelet Membrane Glycoproteins
  • platelet membrane glycoprotein VI
  • Tyrosine
  • Collagen
  • Phosphatidylinositol 3-Kinases
  • Class Ia Phosphatidylinositol 3-Kinase
  • PTPN11 protein, human
  • Protein Tyrosine Phosphatase, Non-Receptor Type 11
  • Ptpn11 protein, mouse