Abstract
Infections of bacteria and viruses induce host defense reactions known as innate responses that include the production of cytokines and chemokines. The production of type I interferon (IFN) is known to be induced by viral double-stranded (ds) RNA or bacterial lipopolysaccharide (LPS). Although important functions for the transcription factors NF-kappaB and interferon regulatory factor-3 (IRF-3) are indicated, the molecular signals leading to the activation of IFN genes have yet to be elucidated. We provide several lines of evidence that LPS and dsRNA trigger distinct intracellular signals upstream. Notably, our investigation revealed a critical function for TIRAP/MAL, a signaling adapter for Toll-like receptor (TLR) 4, in LPS-induced but not dsRNA-induced activation of IRF-3. These results highlight cross-talk between TLR-mediated and virus/dsRNA-induced signals resulting in activation of the IFN system.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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Carrier Proteins / metabolism*
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Cells, Cultured
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DNA-Binding Proteins / drug effects
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DNA-Binding Proteins / metabolism*
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Humans
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Interferon Regulatory Factor-3
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JNK Mitogen-Activated Protein Kinases
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Lipopolysaccharides / pharmacology*
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Membrane Glycoproteins*
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Mice
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Mitogen-Activated Protein Kinases / metabolism
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RNA, Double-Stranded / pharmacology
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Receptors, Interleukin-1 / metabolism*
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Signal Transduction / drug effects
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Signal Transduction / physiology
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Transcription Factors / drug effects
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Transcription Factors / metabolism*
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Tumor Cells, Cultured
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p38 Mitogen-Activated Protein Kinases
Substances
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Carrier Proteins
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DNA-Binding Proteins
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IRF3 protein, human
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Interferon Regulatory Factor-3
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Irf3 protein, mouse
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Lipopolysaccharides
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Membrane Glycoproteins
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RNA, Double-Stranded
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Receptors, Interleukin-1
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TIRAP protein, human
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TIRAP protein, mouse
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Transcription Factors
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JNK Mitogen-Activated Protein Kinases
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Mitogen-Activated Protein Kinases
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p38 Mitogen-Activated Protein Kinases