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J. Exp. Med.,
Volume 187, Number 12, June 15, 1998 2023-2030
By

From the * Department of Dermatology, Division of General Dermatology, University of Vienna
Medical School, Vienna, A-1090 Austria; the Tumor necrosis factor (TNF) and interleukin 1 are known to initiate endothelial vascular cell
adhesion molecule (VCAM)-1 transcription primarily by activating nuclear factor (NF)-
Department of Dermatology, Goethe University,
Frankfurt, Germany 60590; and the § Boyer Center of Molecular Biology, Yale University, New
Haven, Connecticut 06536
B,
which translocates to the nucleus. In addition to two NF-
B elements found within the minimal cytokine-inducible VCAM-1 promoter, an interferon-related factor (IRF) element (IRF-1)
has been identified close to the transcription initiation site, suggesting that cytokines that induce IRF-1 might affect VCAM-1 expression levels. We therefore investigated the effects of
interferons (IFNs), which strongly induce IRF-1, on VCAM-1 transcription and expression.
We show that IFN-
and -
enhance TNF-induced VCAM-1 mRNA transcription and protein expression in human endothelial cells. IFN enhancement of TNF-induced expression is
also seen using chloramphenicol acetyl transferase reporter genes linked to the minimal cytokine inducible VCAM-1 promoter. Nuclear IRF-1 is the molecular basis of IFN enhancement, because (a) IFN plus TNF-treated cells displayed increased nuclear IRF-1 levels and increased
IRF-1 binding to the VCAM-1 promoter, compared with cells treated with TNF alone; (b) kinetics of nuclear IRF-1 levels correlated with VCAM-1 mRNA levels; (c) transfection with an
IRF-1 construct substituted for IFN treatment; and (d) transfection with an expression construct encoding IRF-2, a competitive inhibitor of IRF-1, reduced TNF-induced VCAM-1 expression. Our experiments show that IFN amplifies TNF-induced VCAM-1 expression at the
transcriptional level by an IRF-1-dependent pathway.
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