title: Galectin-3 promotes lamellipodia formation in epithelial cells by interacting with complex N-glycans on alpha3beta1 integrin.
abstract: Recent studies have shown that galectin-3 (Gal-3; also known as LGALS3), a beta-galactoside-binding lectin, promotes cell migration during re-epithelialization of corneal wounds. The goal of this study was to characterize the molecular mechanism by which Gal-3 stimulates cell migration. We demonstrate here that exogenous Gal-3, but not Gal-1 or Gal-8, promotes cell scattering and formation of lamellipodia in human corneal epithelial cells in a beta-lactose-inhibitable manner. alpha3beta1 integrin was identified as the major Gal-3-binding protein in corneal epithelial cells by affinity chromatography of cell lysates on a Gal-3-Sepharose column. Preincubation of cells with anti-alpha3 integrin function-blocking antibody significantly inhibited the induction of lamellipodia by Gal-3. Furthermore, exogenous Gal-3 activated both focal adhesion kinase, a key regulator of integrin-dependent intracellular signaling, and Rac1 GTPase, a member of the family of Rho GTPases, well known for its role in the reorganization of the actin cytoskeleton and formation of lamellipodial extensions. Experiments involving knockdown of beta-1,6-N-acetylglucosaminytransferase V, an enzyme that synthesizes high-affinity glycan ligands for Gal-3, revealed that carbohydrate-mediated interaction between Gal-3 and complex N-glycans on alpha3beta1 integrin plays a key role in Gal-3-induced lamellipodia formation. We propose that Gal-3 promotes epithelial cell migration by cross-linking MGAT5-modified complex N-glycans on alpha3beta1 integrin and subsequently activating alpha3beta1-integrin-Rac1 signaling to promote lamellipodia formation.
authors.affiliation: Department of Ophthalmologyand The New England Eye Center, Tufts University School of Medicine, Sackler School of Graduate Biomedical Sciences, Boston, MA 02111, USA.
authors.forename: Chandrassegar
authors.initials: C
authors.lastname: Saravanan
authors.forename: Fu-Tong
authors.initials: FT
authors.lastname: Liu
authors.forename: Ilene K
authors.initials: IK
authors.lastname: Gipson
authors.forename: Noorjahan
authors.initials: N
authors.lastname: Panjwani
mesh_terms: D000911:Antibodies, Monoclonal / Q000494:pharmacology; D002465:Cell Movement / Q000187:drug effects; D004789:Enzyme Activation / Q000187:drug effects; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D019573:Epithelium, Corneal / Q000166:cytology / Q000201:enzymology; D051416:Focal Adhesion Protein-Tyrosine Kinases / Q000378:metabolism; D037502:Galectin 3 / Q000378:metabolism*; D055785:Gene Knockdown Techniques; D006801:Humans; D039201:Integrin alpha3beta1 / Q000378:metabolism*; D008954:Models, Biological; D017351:N-Acetylglucosaminyltransferases / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000378:metabolism; D011134:Polysaccharides / Q000378:metabolism*; D011485:Protein Binding / Q000187:drug effects; D011554:Pseudopodia / Q000187:drug effects / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D020830:rac1 GTP-Binding Protein / Q000378:metabolism
chemical_list: D000911:Antibodies, Monoclonal; D037502:Galectin 3; D039201:Integrin alpha3beta1; D009419:Nerve Tissue Proteins; D011134:Polysaccharides; D034741:RNA, Small Interfering; C479741:MGAT5B protein, human; D017351:N-Acetylglucosaminyltransferases; D051416:Focal Adhesion Protein-Tyrosine Kinases; D020830:rac1 GTP-Binding Protein