Identification of galectin-1 and galectin-3 as novel partners for von Willebrand factor.

OBJECTIVE Although von Willebrand factor (VWF) is a heavily glycosylated protein, its potential to associate with glycan-binding proteins is poorly investigated. Here, we explored its interaction with the glycan-binding proteins galectin-1 and galectin-3. METHODS AND RESULTS Immunofluorescence analysis using Duolink proximity ligation assays revealed that VWF colocalizes with galectin-1 and galectin-3 in endothelial cells, both before and after stimulation of endothelial cells. Moreover, galectin-1 was found along the typical VWF bundles that are released by endothelial cells. Galectin-1 and galectin-3 could be coprecipitated with VWF from plasma in immunoprecipitation assays, whereas plasma levels of galectin-1 and galectin-3 were significantly reduced in VWF-deficient mice. Binding studies using purified proteins confirmed that VWF could directly interact with both galectins, predominantly via its N-linked glycans. In search of the physiological relevance of the VWF-galectin interaction, we found that inhibition of galectins in in vitro perfusion assays was associated with increased VWF-platelet string formation, a phenomenon that was reproduced in galectin-1/galectin-3 double-deficient mice. These mice were also characterized by a more rapid formation of initial thrombi following ferric chloride-induced injury. CONCLUSIONS We have identified galectin-1 and galectin-3 as novel partners for VWF, and these proteins may modulate VWF-mediated thrombus formation.