title: Apolipoprotein B100 secretion by cultured ARPE-19 cells is modulated by alteration of cholesterol levels.
abstract: Cholesteryl ester rich apolipoprotein B100 (apoB100) lipoproteins accumulate in Bruch's membrane before the development of age-related macular degeneration. It is not known if these lipoproteins come from the circulation or local ocular tissue. Emerging, but incomplete evidence suggests that the retinal pigmented epithelium (RPE) can secrete lipoproteins. The purpose of this investigation was to determine (i) whether human RPE cells synthesize and secrete apoB100, and (ii) whether this secretion is driven by cellular cholesterol, and if so, (iii) whether statins inhibit this response. The established, human derived ARPE-19 cells challenged with 0-0.8 mM oleic acid accumulated cellular cholesterol, but not triglycerides. Oleic acid increased the amount of apoB100 protein recovered from the medium by both western blot analysis and (35) S-radiolabeled immunoprecipitation while negative stain electron microscopy showed lipoprotein-like particles. Of nine statins evaluated, lipophilic statins induced HMG-CoA reductase mRNA expression the most. The lipophilic Cerivastatin (5 μM) reduced cellular cholesterol by 39% and abrogated apoB100 secretion by 3-fold. In contrast, the hydrophilic statin Pravastatin had minimal effect on apoB100 secretion. These data suggest that ARPE-19 cells synthesize and secrete apoB100 lipoproteins, that this secretion is driven by cellular cholesterol, and that statins can inhibit apoB100 secretion by reducing cellular cholesterol.
authors.affiliation: Wilmer Eye Institute, Johns Hopkins School of Medicine, Baltimore, Maryland, USA.
authors.forename: Tinghuai
authors.initials: T
authors.lastname: Wu
authors.forename: Masashi
authors.initials: M
authors.lastname: Fujihara
authors.forename: Jane
authors.initials: J
authors.lastname: Tian
authors.forename: Miroslava
authors.initials: M
authors.lastname: Jovanovic
authors.forename: Celene
authors.initials: C
authors.lastname: Grayson
authors.forename: Marisol
authors.initials: M
authors.lastname: Cano
authors.forename: Peter
authors.initials: P
authors.lastname: Gehlbach
authors.forename: Philippe
authors.initials: P
authors.lastname: Margaron
authors.forename: James T
authors.initials: JT
authors.lastname: Handa
mesh_terms: D000975:Antioxidants / Q000494:pharmacology; D053299:Apolipoprotein B-100 / Q000378:metabolism*; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D002784:Cholesterol / Q000378:metabolism*; D006801:Humans; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000494:pharmacology; D019301:Oleic Acid / Q000494:pharmacology; D011725:Pyridines / Q000494:pharmacology; D014280:Triglycerides / Q000378:metabolism
chemical_list: D000975:Antioxidants; D053299:Apolipoprotein B-100; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D011725:Pyridines; D014280:Triglycerides; D019301:Oleic Acid; D002784:Cholesterol; C086276:cerivastatin