Abstract
The desmosomal cadherins, desmogleins, and desmocollins mediate strong intercellular adhesion. Human intestinal epithelial cells express the desmoglein-2 isoform. A proteomic screen for Dsg2-associated proteins in intestinal epithelial cells identified a lectin referred to as galectin-3 (Gal3). Gal3 bound to N-linked β-galactosides in Dsg2 extracellular domain and co-sedimented with caveolin-1 in lipid rafts. Down-regulation of Gal3 protein or incubation with lactose, a galactose-containing disaccharide that competitively inhibits galectin binding to Dsg2, decreased intercellular adhesion in intestinal epithelial cells. In the absence of functional Gal3, Dsg2 protein was internalized from the plasma membrane and degraded in the proteasome. These results report a novel role of Gal3 in stabilizing a desmosomal cadherin and intercellular adhesion in intestinal epithelial cells.
Highlights
These results report a novel role of Gal3 in stabilizing a desmosomal cadherin and intercellular adhesion in intestinal epithelial cells
To identify proteins that regulate Dsg2-mediated intercellular adhesion, we performed mass spectrometry of proteins that co-immunoprecipitated with Dsg2 using a model intestinal epithelial cell line (T84)
To determine whether Gal3 association with Dsg2 is mediated through glycan binding, IECs were incubated with lactose that competitively inhibits galectin-glycan interaction prior to Dsg2 immunoprecipitation
Summary
Conclusion: Galectin-3 lattices stabilize desmoglein-2 at the cell surface to regulate intercellular adhesion in intestinal epithelial cells. A proteomic screen for Dsg2-associated proteins in intestinal epithelial cells identified a lectin referred to as galectin-3 (Gal). Down-regulation of Gal protein or incubation with lactose, a galactose-containing disaccharide that competitively inhibits galectin binding to Dsg, decreased intercellular adhesion in intestinal epithelial cells. In the absence of functional Gal, Dsg protein was internalized from the plasma membrane and degraded in the proteasome These results report a novel role of Gal in stabilizing a desmosomal cadherin and intercellular adhesion in intestinal epithelial cells. We observed that Gal association with Dsg is mediated by N-linked glycans on Dsg and that this lactose-sensitive interaction promotes Dsg stability at the cell surface and epithelial intercellular adhesion
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