Apolipoprotein B100 secretion by cultured ARPE-19 cells is modulated by alteration of cholesterol levels.
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.
Wu
Tinghuai
T
Wilmer Eye Institute, Johns Hopkins School of Medicine, Baltimore, Maryland, USA.
Fujihara
Masashi
M
Tian
Jane
J
Jovanovic
Miroslava
M
Grayson
Celene
C
Cano
Marisol
M
Gehlbach
Peter
P
Margaron
Philippe
P
Handa
James T
JT
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
D000975:Antioxidants; D053299:Apolipoprotein B-100; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D011725:Pyridines; D014280:Triglycerides; D019301:Oleic Acid; D002784:Cholesterol; C086276:cerivastatin