Galectin-3 regulates integrin alpha2beta1-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 alpha(2)beta(1), 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 alpha(2)beta(1)-mediated adhesion complex formation by altering receptor clustering.