Copyright © 2005, European Society of Cardiology
Oxidized LDL downregulates ATP-binding cassette transporter-1 in human vascular endothelial cells via inhibiting liver X receptor (LXR)
aDepartment of Physiology, Key Laboratory of Molecular Cardiovascular Sciences of Education Ministry, Health Science Center, Peking University, Beijing 100083, China
bDivision of Biomedical Sciences, University of California, Riverside, Riverside, CA 92521, United States
* Corresponding author. Department of Physiology and Pathophysiology, Peking University, Health Sciences Center, Beijing 100083, China. Tel.: +86 10 8280 1440; fax: +86 10 8280 1440. Email address: zhuyi{at}bjmu.edu.cn
Objective: ATP-binding cassette transporter-1 (ABCA1) mediates the active efflux of cholesterol and phospholipids, playing an important role in cholesterol homeostasis and atherogenesis. Oxidized low density lipoprotein (oxLDL) is an atherogenic molecule associated with the vascular endothelial dysfunction and development of atherosclerotic plaque. This report describes the effect of copper-catalyzed oxLDL on the regulation of ABCA1 in human endothelial cells (ECs).
Methods and results: oxLDL downregulated ABCA1 at both mRNA and protein levels in a dose-dependent manner. This inhibitory effect of oxLDL was observed with both minimally and extensively oxLDL. Transfection of the ABCA1 promoter luciferase revealed oxLDL to substantially decrease ABCA1 promoter activity at basal conditions and after stimulation by overexpressing the liver X receptor LXR
and retinoid X receptor RXR. oxLDL also attenuated LXR activation by blocking LXR ligand binding and interfering with the generation of 27-hydroxycholesterol, an LXR endogenous ligand. Furthermore, oxLDL inhibited exogenous cholesterol- and oxysterol-induced endothelial ABCA1 induction.
Conclusion: oxLDL downregulated ABCA1 by inhibiting LXR activation in endothelial cells. Such an effect may contribute to endothelial dysfunction and plaque formation.
KEYWORDS Cholesterol; Endothelial function; Gene expression; Lipoprotein; Membrane transport
Time for primary review 30 days
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