Abstract
We and others have reported that IFN-alpha potentiates the apoptotic effects of TNF through a mechanism that is not understood. Because the nuclear transcription factors NF-kappaB and AP-1 have recently been reported to mediate anti-apoptosis and cell survival, we hypothesized that IFN-alpha potentiates the cytotoxic effects of TNF by suppressing TNF-induced activation of NF-kappaB and AP-1. We tested this hypothesis by pretreating human Jurkat T cells with IFN-alpha, which blocked TNF-induced activation of NF-kappaB and AP-1 in a time- and dose-dependent manner as determined by EMSA. IFN-alpha blocked TNF-induced phosphorylation and degradation of the inhibitor subunit of NF-kappaB, and suppressed NF-kappaB and AP-1 activation induced by various other inflammatory stimuli. NF-kappaB-dependent reporter gene expression activated by TNF, TNFR1, TNF receptor-associated factor 2, and NF-kappaB-inducing kinase was also abrogated by IFN-alpha pretreatment. The suppression of NF-kappaB and AP-1 correlated with the potentiation of TNF-induced cytotoxicity and caspase activation. Overall our results suggest that IFN-alpha potentiates the apoptotic effects of TNF possibly by suppressing NF-kappaB and AP-1 activation.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Apoptosis / genetics
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Apoptosis / immunology*
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Caspases / metabolism
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Ceramides / antagonists & inhibitors
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Ceramides / pharmacology
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Cytotoxicity, Immunologic / immunology
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DNA-Binding Proteins / antagonists & inhibitors
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DNA-Binding Proteins / metabolism
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Drug Synergism
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Enzyme Activation / immunology
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Gene Expression Regulation / immunology
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Genes, Reporter / immunology
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Humans
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I-kappa B Proteins*
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Immunosuppressive Agents / pharmacology*
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Interferon-alpha / physiology*
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Jurkat Cells
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Lipopolysaccharides / antagonists & inhibitors
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Lipopolysaccharides / pharmacology
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NF-KappaB Inhibitor alpha
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NF-kappa B / antagonists & inhibitors*
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NF-kappa B / genetics
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NF-kappa B / metabolism
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NF-kappa B p50 Subunit
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Phosphorylation
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Transcription Factor AP-1 / antagonists & inhibitors*
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Transcription Factor AP-1 / metabolism
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Transcription Factor RelA
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Transfection
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Tumor Necrosis Factor-alpha / antagonists & inhibitors
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Tumor Necrosis Factor-alpha / genetics
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Tumor Necrosis Factor-alpha / physiology*
Substances
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Ceramides
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DNA-Binding Proteins
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I-kappa B Proteins
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Immunosuppressive Agents
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Interferon-alpha
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Lipopolysaccharides
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NF-kappa B
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NF-kappa B p50 Subunit
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NFKBIA protein, human
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Transcription Factor AP-1
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Transcription Factor RelA
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Tumor Necrosis Factor-alpha
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NF-KappaB Inhibitor alpha
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Caspases