title: ApoC-III content of apoB-containing lipoproteins is associated with binding to the vascular proteoglycan biglycan.
abstract: Retention of apolipoprotein (apo)B and apoE-containing lipoproteins by extracellular vascular proteoglycans is critical in atherogenesis. Moreover, high circulating apoC-III levels are associated with increased atherosclerosis risk. To test whether apoC-III content of apoB-containing lipoproteins affects their ability to bind to the vascular proteoglycan biglycan, we evaluated the impact of apoC-III on the interaction of [(35)S]SO(4)-biglycan derived from cultured arterial smooth muscle cells with lipoproteins obtained from individuals across a spectrum of lipid concentrations. The extent of biglycan binding correlated positively with apoC-III levels within VLDL (r = 0.78, P < 0.01), IDL (r = 0.67, P < 0.01), and LDL (r = 0.52, P < 0.05). Moreover, the biglycan binding of VLDL, IDL, and LDL was reduced after depletion of apoC-III-containing lipoprotein particles in plasma by anti-apoC-III immunoaffinity chromatography. Since apoC-III does not bind biglycan directly, enhanced biglycan binding may result from a conformational change associated with increased apo C-III content by which apoB and/or apoE become more accessible to proteoglycans. This may be an intrinsic property of lipoproteins, since exogenous apoC-III enrichment of LDL and VLDL did not increase binding. ApoC-III content may thus be a marker for lipoproteins characterized as having an increased ability to bind proteoglycans.
authors.affiliation: Department of Medicine, University of Washington, Seattle, WA, USA.
authors.forename: Katherine
authors.initials: K
authors.lastname: Olin-Lewis
authors.forename: Ronald M
authors.initials: RM
authors.lastname: Krauss
authors.forename: Michael
authors.initials: M
authors.lastname: La Belle
authors.forename: Patricia J
authors.initials: PJ
authors.lastname: Blanche
authors.forename: P Hugh R
authors.initials: PH
authors.lastname: Barrett
authors.forename: Thomas N
authors.initials: TN
authors.lastname: Wight
authors.forename: Alan
authors.initials: A
authors.lastname: Chait
mesh_terms: D053305:Apolipoprotein C-III; D001055:Apolipoproteins B / Q000032:analysis* / Q000097:blood; D001056:Apolipoproteins C / Q000032:analysis* / Q000097:blood; D058578:Biglycan; D002846:Chromatography, Affinity; D016326:Extracellular Matrix Proteins; D006801:Humans; D008074:Lipoproteins / Q000097:blood / Q000737:chemistry*; D008077:Lipoproteins, LDL / Q000097:blood / Q000737:chemistry; D008079:Lipoproteins, VLDL / Q000097:blood / Q000737:chemistry; D010316:Particle Size; D011509:Proteoglycans / Q000378:metabolism*
chemical_list: D053305:Apolipoprotein C-III; D001055:Apolipoproteins B; D001056:Apolipoproteins C; C546884:BGN protein, human; D058578:Biglycan; D016326:Extracellular Matrix Proteins; D008074:Lipoproteins; D008077:Lipoproteins, LDL; D008079:Lipoproteins, VLDL; D011509:Proteoglycans