ALTERATIONS OF HEPARAN-SULFATE MOIETIES IN CULTURED ENDOTHELIAL-CELLSEXPOSED TO ENDOTOXIN

In previous studies, we observed that exposure to endotoxin markedly r educes the level of heparan sulfate proteoglycans in the extracellular matrix of cultured endothelial cells and at the same time causes the accumulation of proteoglycans bearing glycosaminoglycan chains of redu ced size in the conditioned medium (P. Colburn, E. Kobayashi, and V. B uonassisi, 1994, J. Cell. Physiol. 159, 121-130). We have now investig ated the structural and ligand-binding features which distinguish the matrix glycosaminoglycan moiety and the nature of the alterations of t he truncated glycosaminoglycans. The matrix glycosaminoglycans are les s sulfated than those of other cellular compartments and are more exte nsively degraded by heparitinase I, yielding a larger proportion of sm aller oligosaccharides. In the binding assays, matrix glycosaminoglyca ns had greater specificity than those of the cell surface for a synthe tic peptide patterned on the carboxyl-terminal sequence of an N-glycan sulfated protein synthesized by the endothelial cell. The nature of t he alteration caused by exposure to endotoxin consists in the loss of a region rich in sulfate, located at the nonreducing end of the glycos aminoglycan chain, We also determined that only proteoglycans with int act chains are found in the extracellular matrix of endotoxin-treated cells. (C) 1996 Academic Press, Inc.