title: Modulation of ocular surface glycocalyx barrier function by a galectin-3 N-terminal deletion mutant and membrane-anchored synthetic glycopolymers.
abstract: BACKGROUND
  Interaction of transmembrane mucins with the multivalent carbohydrate-binding protein galectin-3 is critical to maintaining the integrity of the ocular surface epithelial glycocalyx. This study aimed to determine whether disruption of galectin-3 multimerization and insertion of synthetic glycopolymers in the plasma membrane could be used to modulate glycocalyx barrier function in corneal epithelial cells.
  
  
  RESULTS
  Abrogation of galectin-3 biosynthesis in multilayered cultures of human corneal epithelial cells using siRNA, and in galectin-3 null mice, resulted in significant loss of corneal barrier function, as indicated by increased permeability to the rose bengal diagnostic dye. Addition of β-lactose, a competitive carbohydrate inhibitor of galectin-3 binding activity, to the cell culture system, transiently disrupted barrier function. In these experiments, treatment with a dominant negative inhibitor of galectin-3 polymerization lacking the N-terminal domain, but not full-length galectin-3, prevented the recovery of barrier function to basal levels. As determined by fluorescence microscopy, both cellobiose- and lactose-containing glycopolymers incorporated into apical membranes of corneal epithelial cells, independently of the chain length distribution of the densely glycosylated, polymeric backbones. Membrane incorporation of cellobiose glycopolymers impaired barrier function in corneal epithelial cells, contrary to their lactose-containing counterparts, which bound to galectin-3 in pull-down assays.
  
  
  CONCLUSIONS
  These results indicate that galectin-3 multimerization and surface recognition of lactosyl residues is required to maintain glycocalyx barrier function at the ocular surface. Transient modification of galectin-3 binding could be therapeutically used to enhance the efficiency of topical drug delivery.
authors: Schepens Eye Research Institute and Massachusetts Eye and Ear, Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts, United States of America.
authors: Jerome
authors: J
authors: Mauris
authors: Flavio
authors: F
authors: Mantelli
authors: Ashley M
authors: AM
authors: Woodward
authors: Ziyhi
authors: Z
authors: Cao
authors: Carolyn R
authors: CR
authors: Bertozzi
authors: Noorjahan
authors: N
authors: Panjwani
authors: Kamil
authors: K
authors: Godula
authors: Pablo
authors: P
authors: Argüeso
mesh_terms: D000818:Animals; D001692:Biological Transport; D002475:Cellobiose / Q000737:chemistry; D002478:Cells, Cultured; D003315:Cornea / Q000737:chemistry / Q000166:cytology / Q000187:drug effects*; D004847:Epithelial Cells / Q000737:chemistry / Q000187:drug effects*; D037502:Galectin 3 / Q000172:deficiency / Q000235:genetics*; D019276:Glycocalyx / Q000737:chemistry / Q000187:drug effects*; D006001:Glycoconjugates / Q000138:chemical synthesis / Q000378:metabolism / Q000494:pharmacology*; D006801:Humans; D007785:Lactose / Q000737:chemistry; D051379:Mice; D018345:Mice, Knockout; D009077:Mucins / Q000737:chemistry / Q000378:metabolism; D010539:Permeability; D055503:Protein Multimerization; D017434:Protein Structure, Tertiary; D012395:Rose Bengal / Q000378:metabolism; D013329:Structure-Activity Relationship
chemical_list: D037502:Galectin 3; D006001:Glycoconjugates; D009077:Mucins; D002475:Cellobiose; D012395:Rose Bengal; D007785:Lactose
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