Lead-induced alteration of heparan sulfate proteoglycans in cultured vascular endothelial cells

Abstract

We investigated the alterations of heparan sulfate proteoglycans produced by vascular endothelial cells after exposure to lead. Bovine aortic endothelial cells were cultured and metabolically labeled with [ 3H]glucosamine and [ 35S]sulfate in the presence of lead chloride at 10 μM. Radiolabeled HSPGs were separated by ion-exchange chromatography and either their hydrodynamic size or the length of heparan sulfate chains were characterized by gel filtration. It was found that lead markedly suppresses the incorporation of the radioactive precursors into HSPGs in the cell layer; the incorporation into chondroitin/dermatan sulfate proteoglycans was decreased by the metal only slightly. The suppression by lead occurred in the low molecular weight subclass of HSPGs rather than the high molecular weight subclass. However, the length of heparan sulfate chains was not changed by the metal. A sodium dodecyl sulfate-polyacrylamide gel electrophoresis of [ 35S]methionine-labeled proteoglycans after heparitinase digestion showed that there were slightly more HSPG core proteins without a change of the size in lead-treated cell layer. It was, therefore, suggested that vascular endothelial cell layer after exposure to lead has more HSPG core proteins with fewer heparan sulfate chains without a change in length.