title: Galectin-3 protein modulates cell surface expression and activation of vascular endothelial growth factor receptor 2 in human endothelial cells.
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.
authors.affiliation: Graduate Program in Biochemistry, Sackler School of Graduate Biomedical Sciences, Tufts University, Boston, Massachusetts 02111, USA.
authors.forename: Anna I
authors.initials: AI
authors.lastname: Markowska
authors.forename: Kevin C
authors.initials: KC
authors.lastname: Jefferies
authors.forename: Noorjahan
authors.initials: N
authors.lastname: Panjwani
mesh_terms: D000818:Animals; D002462:Cell Membrane / Q000235:genetics / Q000378:metabolism; D002478:Cells, Cultured; D016510:Corneal Neovascularization / Q000235:genetics / Q000378:metabolism; D042783:Endothelial Cells / Q000166:cytology / Q000378:metabolism*; D004789:Enzyme Activation / Q000502:physiology; D037502:Galectin 3 / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000502:physiology*; D006801:Humans; D051379:Mice; D018345:Mice, Knockout; D017351:N-Acetylglucosaminyltransferases / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000378:metabolism*; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000096:biosynthesis* / Q000235:genetics
chemical_list: D037502:Galectin 3; C485095:Lgals3 protein, mouse; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; C467480:vascular endothelial growth factor A, mouse; D017351:N-Acetylglucosaminyltransferases; C052254:alpha-1,6-mannosylglycoprotein beta 1,6-N-acetylglucosaminyltransferase; D040301:Vascular Endothelial Growth Factor Receptor-2