Abstract
The cytokines secreted by lung macrophages have been shown to play a critical role in the pathogenesis of silicosis, tumor necrosis factor-alpha (TNF-alpha), and transforming growth factor-beta1 (TGF-beta1) are prominent cytokines in silicosis, but the underlying mechanism remains to be determined. The aim of the present study was to investigate the roles of Src-mitogen-activated protein kinase (MAPKs)/activator protein-1 (AP-1) signaling pathways in silica-induced TNF-alpha and TGF-beta1 expression in macrophage cells (RAW264.7). It was found that silica activated Src, p38 kinase, and extracellular signal-regulated kinase (ERK) in RAW264.7 cells. The induction of TNF-alpha and TGF-beta1 by silica was suppressed by Src inhibitor (PP1), ERK inhibitor (PD98059), but not by p38 kinase inhibitor (SB203580). Dominant negative mutant c-Jun (TAM67) inhibited silica-induced AP-1 DNA binding activity and downregulated the TNF-alpha and TGF-beta1 expression. In addition, PD98059 but not SB203580 inhibited the AP-1 DNA binding activity induced by silica. Based on these findings, it was conclude that Src-ERK/AP-1 signaling pathways are involved in the TNF-alpha and TGF-beta1 expression induced by silica in macrophages.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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Blotting, Western
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Cell Culture Techniques
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Cell Line
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Electrophoresis, Polyacrylamide Gel
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Environmental Pollutants / toxicity*
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Enzyme Inhibitors / pharmacology
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Enzyme-Linked Immunosorbent Assay
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Extracellular Signal-Regulated MAP Kinases / antagonists & inhibitors
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Extracellular Signal-Regulated MAP Kinases / metabolism
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Macrophages, Alveolar / drug effects*
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Macrophages, Alveolar / enzymology
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Macrophages, Alveolar / immunology
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Macrophages, Alveolar / metabolism
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Mice
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Peptide Fragments / genetics
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Phosphorylation
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Plasmids
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Protein Binding
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Proto-Oncogene Proteins c-jun / genetics
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Signal Transduction / drug effects
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Silicon Dioxide / toxicity*
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Silicosis / enzymology
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Silicosis / etiology
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Silicosis / metabolism
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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 AP-1 / physiology
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Transfection
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Transforming Growth Factor beta1 / biosynthesis*
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Tumor Necrosis Factor-alpha / biosynthesis*
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p38 Mitogen-Activated Protein Kinases / antagonists & inhibitors
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p38 Mitogen-Activated Protein Kinases / metabolism
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src-Family Kinases / antagonists & inhibitors
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src-Family Kinases / metabolism*
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src-Family Kinases / physiology
Substances
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Environmental Pollutants
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Enzyme Inhibitors
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Peptide Fragments
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Proto-Oncogene Proteins c-jun
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TAM67 peptide
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Transcription Factor AP-1
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Transforming Growth Factor beta1
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Tumor Necrosis Factor-alpha
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Silicon Dioxide
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src-Family Kinases
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Extracellular Signal-Regulated MAP Kinases
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p38 Mitogen-Activated Protein Kinases