Lipoprotein lipase enhances the binding of native and oxidized low densitylipoproteins to versican and biglycan synthesized by cultured arterial smooth muscle cells

Retention of low density lipoproteins (LDL) by vascular proteoglycans and t heir subsequent oxidation are important in atherogenesis, Lipoprotein lipas e (LPL) can bind LDL and proteoglycans, although the effect of different pr oteoglycans to influence the ability of LPL to act as a bridge in the forma tion of LDL-proteoglycan complexes is unknown. Using an electrophoretic gel mobility shift assay, [S-35]SO4-labeled versican and biglycan, two extrace llular proteoglycans secreted by vascular cells, bound native LDL in a satu rable fashion, The addition of bovine milk LPL dose-dependently increased t he binding of native LDL to both versican and biglycan, approaching saturat ion at 30-40 mu g/ml LPL for versican and 20 mu g/ml LPL for biglycan. LDL was oxidized by several methods, including copper, 2,2-azobis(2-amidinoprop ane)-2HCl and hypochlorite, Extensively copper- and hypochlorite-oxidized L DL bound poorly to versican and biglycan, Proteoglycan binding to LDL was c orrelated inversely with the extent of LDL; however, the addition of LPL to oxidized LDL together with biglycan or versican allowed the oxidized LDL t o bind the proteoglycans in an LPL dose-dependent manner. Addition of LPL h ad a greater relative effect on the binding of extensively oxidized LDL to proteoglycans compared with native LDL, LPL had a slightly greater effect o n increasing the binding of native and oxidized LDL to biglycan than versic an, Thus, LPL in the artery wall might increase the atherogenicity of oxidi zed LDL, since it enables its binding to vascular biglycan and versican.