Effect of lectins on the metabolism of sulfated glycosaminolycans in cultured fibroblasts.

A short exposure of human skin fibroblasts to Concanavalin A and wheat germ agglutinin led to an intra- and extracellular accumulation of sulfated glycosaminoglycans. The intracellular accumulation was caused by an impaired degradation of sulfated glycosaminoglycans. The increase of extracellular and cell surface associated 35S-labeled proteoglycans could be ascribed to a lectin-mediated inhibition of endocytosis of these polysaccharides. Results obtained with mono- and divalent Concanavalin A derivatives were in agreement with the view that lectins inhibit endocytosis of sulfated proteoglycans by binding to the cell surface receptors specific for these polysaccharides. Proteoglycans secreted by fibroblasts formed precipitable complexes with Concanavalin A. Complex formation reduced markedly the uptake of the proteoglycan. All effects on glycosaminoglycan metabolism mediated by Concanavalin A and wheat germ agglutinin could be prevented by methyl alpha-D-mannoside and N-acetylglucoseamine, respectively.