Abstract
Many cells upon injury mount extensive, compensatory responses that increase cell survival; however, the intracellular signals that regulate these responses are not completely understood. Heparin-binding epidermal growth factor-like growth factor (HB-EGF) has been implicated as a cytoprotective agent. We have previously demonstrated that pretreatment of human intestinal epithelial cells with HB-EGF significantly decreased cytokine-induced activation of inducible NO synthase mRNA expression and NO production and protected the cells from apoptosis and necrosis. However, the mechanisms by which HB-EGF exerts these effects are not known. Here we show that cytokine exposure (IL-1beta and IFN-gamma) induced NF-kappaB activation and IL-8 and NO production in DLD-1 cells. Transient expression of a dominant negative form of IkappaBalpha decreased NO production, suggesting that the cytokines stimulated NO production in part through activation of NF-kappaB. HB-EGF dramatically suppressed NF-kappaB activity and IL-8 release and decreased NO production in cells pretreated with HB-EGF. HB-EGF blocked NF-kappaB activation by inhibiting IkappaB kinase activation and IkappaB phosphorylation and degradation, thus interfering with NF-kappaB nuclear translocation, DNA-binding activity, and NF-kappaB-dependent transcriptional activity. The data demonstrate that HB-EGF decreases inflammatory cytokine and NO production by interfering with the NF-kappaB signaling pathway. Inhibition of NF-kappaB may represent one of the mechanisms by which HB-EGF exerts its potent anti-inflammatory and cytoprotective effects.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Active Transport, Cell Nucleus / physiology
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Cell Line, Tumor
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Cell Nucleus / genetics
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Cell Nucleus / metabolism
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Cell Nucleus / physiology
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Cytokines / antagonists & inhibitors
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Cytokines / pharmacology
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DNA-Binding Proteins / antagonists & inhibitors
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DNA-Binding Proteins / metabolism
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Down-Regulation / genetics
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Epidermal Growth Factor / metabolism
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Epidermal Growth Factor / pharmacology*
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HT29 Cells
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Heparin / metabolism
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Heparin-binding EGF-like Growth Factor
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Humans
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I-kappa B Kinase
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I-kappa B Proteins / antagonists & inhibitors*
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I-kappa B Proteins / genetics
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I-kappa B Proteins / metabolism
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Inflammation / immunology
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Inflammation / prevention & control
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Intercellular Signaling Peptides and Proteins
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Interleukin-8 / antagonists & inhibitors
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Interleukin-8 / biosynthesis
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Interleukin-8 / metabolism
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Intestinal Mucosa / enzymology
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Intestinal Mucosa / metabolism
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Intestinal Mucosa / pathology
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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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Nitric Oxide / antagonists & inhibitors
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Nitric Oxide / biosynthesis
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Phosphorylation
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Protein Serine-Threonine Kinases / antagonists & inhibitors*
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Protein Serine-Threonine Kinases / metabolism
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Signal Transduction / physiology
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Transcription, Genetic / physiology
Substances
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Cytokines
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DNA-Binding Proteins
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HBEGF protein, human
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Heparin-binding EGF-like Growth Factor
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I-kappa B Proteins
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Intercellular Signaling Peptides and Proteins
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Interleukin-8
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NF-kappa B
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NFKBIA protein, human
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NF-KappaB Inhibitor alpha
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Nitric Oxide
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Epidermal Growth Factor
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Heparin
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Protein Serine-Threonine Kinases
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CHUK protein, human
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I-kappa B Kinase
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IKBKB protein, human
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IKBKE protein, human