Galectins are a family of carbohydrate-binding proteins with specificity for N-acetyl-lactosamine-containing glycoproteins.Galectin-4, a tandem-repeat-type lectin with affinity to sulfatide and nonsialylated termini of N-glycans, has the ability to regulate adhesion of cells to ECM components and is also involved in polarized membrane trafficking.Galectin-4 expression is concentrated within microvilli in the gastrointestinal epithelium, where it can interact with CD3 and bind activated T cells in the lamina propria during intestinal inflammation. Galectin-4 can also bind lung, spleen and kidney macrophages, although its expression is normally low in these tissues. Neurons and OLGs were identified as a possible source of galectin-4, both in vitro and in vivo. In culture, neurons but not OLGs released galectin-4. In co-cultures, a reduced release of endogenous galectin-4 correlated with the onset of myelination. Galectin-4-reactive sites are transiently expressed on processes of premyelinating primary OLGs, but not on neurons. Neuronal galactin-4 is a candidate for a soluble regulator of OLG differentiation and myelination.

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