Cytokine regulation of low density lipoprotein receptor gene transcription in HepG2 cells

Alison T Stopeck, Andrew C. Nicholson, Francesco P. Mancini, David P. Hajjar

Research output: Contribution to journalArticle

121 Citations (Scopus)

Abstract

Elevated plasma levels of cytokines have been demonstrated in inflammatory, malignant, and infectious diseases. These disease states are often associated with abnormal lipid metabolism and reductions in plasma cholesterol levels. To determine if inflammatory cytokines could influence hepatic lipid metabolism, we evaluated low density lipoprotein (LDL) receptor function and gene expression in cytokine stimulated HepG2 cells, a hepatoblastoma-derived cell line which shares many functional similarities with normal hepatocytes. Tumor necrosis factor-α (TNF) and interleukin-1β (IL-1) increased LDL binding to HepG2 cells in a dose-responsive manner. Other cytokines including macrophage-colony stimulating factor, granulocyte macrophage-colony stimulating factor, and γ-interferon had no significant effects on LDL binding. Increased binding in response to TNF or IL-1 was paralleled by increased steady-state levels of LDL receptor mRNA. Evaluation of LDL receptor mRNA half-life revealed no significant change in mRNA stability between control and TNF- or IL-1-stimulated cells. A fusion gene construct consisting of 1563 base pairs of the 5′-flanking DNA of the human LDL receptor gene was coupled to a luciferase reporter gene, transfected into HepG2 cells, and promoter activity was assayed after TNF and IL-1 challenge to the cells. TNF and IL-1 increased promoter activity 200-400%, while treatment with LDL inhibited promoter activity by 70-85%. TNF or IL-1 co-incubation with LDL could not override transcriptional inhibition by LDL. Pretreatment with cycloheximide prevented induction of LDL receptor mRNA by TNF, but not by IL-1, suggesting stimulation of LDL receptor transcription by TNF requires protein synthesis. We propose that TNF and IL-1, acting via distinct signal transduction pathways, increase surface LDL receptors by increasing gene transcription. Our findings suggest that cytokine-induced hypocholesterolemia may be related to TNF and/or IL-1 stimulation of hepatic LDL receptor gene expression and function.

Original languageEnglish (US)
Pages (from-to)17489-17494
Number of pages6
JournalJournal of Biological Chemistry
Volume268
Issue number23
StatePublished - Aug 15 1993
Externally publishedYes

Fingerprint

LDL Receptors
Hep G2 Cells
Transcription
Interleukin-1
Tumor Necrosis Factor-alpha
Genes
Cytokines
LDL Lipoproteins
Messenger RNA
Lipid Metabolism
Gene expression
Hepatoblastoma
Plasmas
Gene Expression
Signal transduction
Macrophage Colony-Stimulating Factor
Macrophages
Gene Fusion
Liver
RNA Stability

ASJC Scopus subject areas

  • Biochemistry

Cite this

Cytokine regulation of low density lipoprotein receptor gene transcription in HepG2 cells. / Stopeck, Alison T; Nicholson, Andrew C.; Mancini, Francesco P.; Hajjar, David P.

In: Journal of Biological Chemistry, Vol. 268, No. 23, 15.08.1993, p. 17489-17494.

Research output: Contribution to journalArticle

Stopeck, AT, Nicholson, AC, Mancini, FP & Hajjar, DP 1993, 'Cytokine regulation of low density lipoprotein receptor gene transcription in HepG2 cells', Journal of Biological Chemistry, vol. 268, no. 23, pp. 17489-17494.
Stopeck, Alison T ; Nicholson, Andrew C. ; Mancini, Francesco P. ; Hajjar, David P. / Cytokine regulation of low density lipoprotein receptor gene transcription in HepG2 cells. In: Journal of Biological Chemistry. 1993 ; Vol. 268, No. 23. pp. 17489-17494.
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