Galectin-3 protein modulates cell surface expression and activation of vascular endothelial growth factor receptor 2 in human endothelial cells

J Biol Chem. 2011 Aug 26;286(34):29913-21. doi: 10.1074/jbc.M111.226423. Epub 2011 Jun 29.

Abstract

Angiogenesis is heavily influenced by VEGF-A and its family of receptors, particularly VEGF receptor 2 (VEGF-R2). Like most cell surface proteins, VEGF-R2 is glycosylated, although the function of VEGF-R2 with respect to its glycosylation pattern is poorly characterized. Galectin-3, a glycan binding protein, interacts with the EGF and TGFβ receptors, retaining them on the plasma membrane and altering their signal transduction. Because VEGF-R2 is glycosylated and both galectin-3 and VEGF-R2 are involved with angiogenesis, we hypothesized that galectin-3 binds VEGF-R2 and modulates its signal transduction as well. Employing a Western blot analysis approach, we found that galectin-3 induces phosphorylation of VEGF-R2 in endothelial cells. Knockdown of galectin-3 and Mgat5, an enzyme that synthesizes high-affinity glycan ligands of galectin-3, reduced VEGF-A mediated angiogenesis in vitro. A direct interaction on the plasma membrane was detected between galectin-3 and VEGF-R2, and this interaction was dependent on the expression of Mgat5. Using immunofluorescence and cell surface labeling, we found an increase in the level of internalized VEGF-R2 in both Mgat5 and galectin-3 knockdown cells, suggesting that galectin-3 retains the receptor on the plasma membrane. Finally, we observed reduced suture-induced neovascularization in the corneas of Gal3(-/-) and Mgat5(-/-) mice. These findings are consistent with the hypothesis that, like its role with the EGF and TGFβ receptors, galectin-3 contributes to the plasma membrane retention and proangiogenic function of VEGF-R2.

Publication types

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

MeSH terms

  • Animals
  • Cell Membrane / genetics
  • Cell Membrane / metabolism
  • Cells, Cultured
  • Corneal Neovascularization / genetics
  • Corneal Neovascularization / metabolism
  • Endothelial Cells / cytology
  • Endothelial Cells / metabolism*
  • Enzyme Activation / physiology
  • Galectin 3 / genetics
  • Galectin 3 / metabolism*
  • Gene Expression Regulation / physiology*
  • Humans
  • Mice
  • Mice, Knockout
  • N-Acetylglucosaminyltransferases / genetics
  • N-Acetylglucosaminyltransferases / metabolism
  • Signal Transduction / physiology
  • Vascular Endothelial Growth Factor A / genetics
  • Vascular Endothelial Growth Factor A / metabolism*
  • Vascular Endothelial Growth Factor Receptor-2 / biosynthesis*
  • Vascular Endothelial Growth Factor Receptor-2 / genetics

Substances

  • Galectin 3
  • Lgals3 protein, mouse
  • VEGFA protein, human
  • Vascular Endothelial Growth Factor A
  • vascular endothelial growth factor A, mouse
  • N-Acetylglucosaminyltransferases
  • alpha-1,6-mannosylglycoprotein beta 1,6-N-acetylglucosaminyltransferase
  • Vascular Endothelial Growth Factor Receptor-2