Galectin-3 (Gal-3), the only chimera-like galectin, has three structural domains: (a) the NH2 terminal domain containing serine phosphorylation, important for nuclear localization, secretion and oligomerization; (b) a sequence susceptible to metalloprotease (MMP) cleavage; and (c) a C-terminal domain containing the carbohydrate recognition domain (CRD) and an anti-death motif. In turn, oligodendrocytes (OLG) are the resident cells responsible for CNS myelination. OLG undergo morphological and molecular changes along several maturational stages. In this context, the present review summarizes current knowledge of Gal-3 role in OLG differentiation, myelination and remyelination in experimental models of multiple sclerosis (MS). Recombinant Gal-3 (rGal-3) accelerates both OLG differentiation, evidenced by an increase in the number of mature cells to the detriment of immature ones, and actin cytoskeleton dynamics. These changes respond to rGal-3 influence on Akt, Erk 1/2, and ß-catenin signaling pathways. Our most recent results reveal a key temporal window spanning OPC and pre-OLG states for this pro-differentiating action of rGal-3 and identify several targets for rGal-3 binding including proteins related to the cytoskeleton, signaling pathways, metabolism and intracellular trafficking. Gal-3 expression in microglial cells during CPZ-induced demyelination and upon the onset of remyelination favors an M2 phenotype, hence fostering myelin debris phagocytosis through TREM-2b phagocytic receptor and MMP activity modulation, leading to OLG differentiation and remyelination. This evidence indicates that Gal-3 mediates the glial crosstalk and thus fosters remyelination both by driving OLG differentiation and promoting a phagocytic microglial phenotype. These studies also shed light on some of the mechanisms underlying Gal-3 action and open doors for the identification of new Gal-3-regulated pathways to control OLG proliferation and differentiation. Altogether, these data unveil the therapeutic potential of Gal-3 in demyelinating diseases such as MS and may allow the development of new targets.
Galectin-3, Oligodendrocytes, Myelination, Remyelination, Microglia, Cytoskeleton, Cuprizone