Transcriptional regulation of deoxynivalenol-induced IL-8 expression in human monocytes.
The trichothecene mycotoxin deoxynivalenol (DON), commonly present in contaminated grains worldwide, induces expression of the chemokine interleukin (IL)-8 in human monocytes. The purpose of this study was to test the hypothesis that DON modulates transcriptional and posttranscriptional regulation of IL-8 expression in the U937 human monocyte model. When U937 cells were transfected with a wild-type IL-8 promoter luciferase construct (-162/+44 IL-8 LUC) and incubated with DON (1 mug/ml) or the positive control, lipopolysaccharide (LPS) (1 mug/ml), there was a significant increase in luciferase expression. Mutation of the nuclear factor-kappaB (NF-kappaB) binding site significantly impaired both DON- and LPS-induced luciferase expression. In contrast, mutating the activator protein-1 binding site resulted in significantly increased DON- and LPS-induced luciferase expression. CCAAT/enhancer-binding protein beta, octamer-1, or NF-kappaB repressing factor binding site mutations did not affect DON-induced luciferase activity. Consistent with reporter studies, the NF-kappaB inhibitor caffeic acid phenethyl ester completely ablated both DON-induced IL-8 mRNA and protein expression. When NF-kappaB subunit binding to a specific IL-8 promoter probe was evaluated by enzyme-linked immunosorbent assay (ELISA), DON was observed to increase p65 binding by 21-fold, have no effect on p50 binding and decrease p52 binding. DON was not found to stabilize IL-8 mRNA in U937 cells. Taken together, these data suggest that DON-induced IL-8 expression is likely to be mediated at the transcriptional level by NF-kappaB, specifically p65, but does not appear to involve mRNA stabilization.
Gray
Jennifer S
JS
Department of Microbiology and Molecular Genetics, Center for Integrative Toxicology, Michigan State University, East Lansing, Michigan 48824-1224, USA.
Pestka
James J
JJ
D022782:CCAAT-Enhancer-Binding Protein-beta / Q000502:physiology; D002478:Cells, Cultured; D005786:Gene Expression Regulation / Q000187:drug effects*; D006801:Humans; D016209:Interleukin-8 / Q000235:genetics*; D009000:Monocytes / Q000378:metabolism*; D016328:NF-kappa B / Q000502:physiology; D020871:RNA Stability; D051996:Transcription Factor RelA / Q000378:metabolism; D014158:Transcription, Genetic; D014255:Trichothecenes / Q000494:pharmacology*; D048051:p38 Mitogen-Activated Protein Kinases / Q000502:physiology
D022782:CCAAT-Enhancer-Binding Protein-beta; D016209:Interleukin-8; D016328:NF-kappa B; D051996:Transcription Factor RelA; D014255:Trichothecenes; D048051:p38 Mitogen-Activated Protein Kinases; C007262:deoxynivalenol