Galectin-3 Regulates Integrin α₂β₁-mediated Adhesion to Collagen-I and -IV*

Galectins are a taxonomically widespread family of galactose-binding proteins of which galectin-3 is known to modulate cell adhesion. Using single cell force spectroscopy, the contribution of galectin-3 to the adhesion of Madin-Darby canine kidney (MDCK) cells to different extracellular matrix proteins was investigated. When adhering to collagen-I or –IV, some cells rapidly entered an enhanced adhesion state, marked by a significant increase in the force required for cell detachment. Galectin-3-depleted cells had an increased probability of entering the enhanced adhesion state. Adhesion enhancement was specific to integrin α₂β₁, as it was not observed when cells adhered to extracellular matrix substrates by other integrins. The adhesion phenotype of galectin-3-depleted cells was mimicked in a galactoside-deficient MDCK cell line and could be complemented by the addition of recombinant galectin-3. We propose that galectin-3 influences integrin α₂β₁-mediated adhesion complex formation by altering receptor clustering.