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Mechanisms of dysregulation of low-density lipoprotein receptor expression in vascular smooth muscle cells by inflammatory cytokines

Ruan, XZ; Moorhead, JF; Tao, JL; Ma, KL; Wheeler, DC; Powis, SH; Varghese, Z; (2006) Mechanisms of dysregulation of low-density lipoprotein receptor expression in vascular smooth muscle cells by inflammatory cytokines. ARTERIOSCL THROM VAS , 26 (5) 1150 - 1155. 10.1161/01.ATV.0000217957.93135.c2. Green open access

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Abstract

Objective - Although inflammation is a recognized feature of atherosclerosis, the impact of inflammation on cellular cholesterol homeostasis is unclear. This study focuses on the molecular mechanisms by which inflammatory cytokines disrupt low-density lipoprotein (LDL) receptor regulation.Methods and Results - IL-1 beta enhanced transformation of vascular smooth muscle cells into foam cells by increasing uptake of unmodified LDL via LDL receptors and by enhancing cholesterol esterification as demonstrated by Oil Red O staining and direct assay of intracellular cholesterol concentrations. In the absence of IL-1 beta, a high concentration of LDL decreased LDL receptor promoter activity, mRNA synthesis and protein expression. However, IL-1 beta enhanced LDL receptor expression, overriding the suppression usually induced by a high concentration of LDL and inappropriately increasing LDL uptake. Exposure to IL-1 beta also caused overexpression of the sterol regulatory element binding protein ( SREBP) cleavage-activating protein ( SCAP), and enhanced its translocation from the endoplasmic reticulum to the Golgi, where it is known to cleave SREBP, thereby enhancing LDL receptor gene expression.Conclusions - These observations demonstrate that IL-1 beta disrupts cholesterol-mediated LDL receptor feedback regulation, permitting intracellular accumulation of unmodified LDL and causing foam cell formation. The implication of these findings is that inflammatory cytokines may contribute to intracellular LDL accumulation without previous modification of the lipoprotein.

Type: Article
Title: Mechanisms of dysregulation of low-density lipoprotein receptor expression in vascular smooth muscle cells by inflammatory cytokines
Open access status: An open access version is available from UCL Discovery
DOI: 10.1161/01.ATV.0000217957.93135.c2
Keywords: atherosclerosis, cytokine, LDL receptor, SREBP cleavage-activating protein, vascular smooth muscle cells, CLEAVAGE-ACTIVATING PROTEIN, CHOLESTEROL HOMEOSTASIS, CARDIOVASCULAR-DISEASE, LDL RECEPTOR, RISK-FACTORS, PATHWAY, GENE, ATHEROSCLEROSIS, PROLIFERATION, TRANSCRIPTION
UCL classification: UCL
UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Medical Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Medical Sciences > Div of Medicine
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Medical Sciences > Div of Medicine > Inst for Liver and Digestive Hlth
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Medical Sciences > Div of Medicine > Renal Medicine
URI: https://discovery.ucl.ac.uk/id/eprint/9057
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