Role of proteoglycan in the binding of low-density lipoprotein to cultured arterial smooth muscle cells.

The role of proteoglycans in the binding of 125I-labeled low-density lipoproteins (LDL) to cultured arterial smooth muscle cells was examined. About 60% of cell bound 125I-labeled LDL could be released by unlabeled LDL, heparin, dextran sulfate or proteoglycan. Binding of 125I-labeled LDL decreased by about 50% when incubated in the presence of exogenous arterial proteoglycans. Exposure of cell cultures to rho-nitrophenyl-beta-D xyloside resulted in a 40% decrease in both the amount of 35S-labeled proteoglycan in the cell layer and the 125I-labeled LDL binding, without modifying significantly the cell number and amount of cell layer protein. These data suggest that cell surface and/or cell matrix proteoglycans may influence binding of LDL to either specific receptor or non-receptor sites and thereby play a role in the intracellular deposition of lipid in the arterial wall.