Novel Galectin-3 interactions involved in oligodendroglial differentiation make inroads into therapeutic strategies for demyelinating diseases

Abstract

Galectins (Gals) constitute a 15-member classof β-galactoside-binding lectins which recognizeN-acetyllactosamine. Despite lacking specificreceptors, Gals form multivalent complexes withcell surface glycoconjugates containing suitableoligosaccharides and thus trigger intracellular signalsto regulate cell survival and differentiation. Galsare classified into three groups on the basis of theirstructural architecture: proto, chimera and tandemtypes, with Gal-3 being the only representativeof the chimeric type. Regarding intracellularlocalization, Gal-3 is found in both cell cytoplasm andnucleus. Extracellular Gal-3 can also be endocytedand, together with intracellular Gal-3, modulatediverse functions binding to intracellular molecules.While lacking a secretion signal peptide, Gal-3 is stillsecreted into the extracellular space by non-classicalpathways potentially involving exosomes. Oncesecreted, Gal-3 binds to poly-N-acetyllactosamine inthe extracellular matrix and membrane receptors,laying bridges to promote or inhibit intracellularevents (Thomas and Pasquini, 2018).