Molecular mechanism of tumor necrosis factor-alpha production in 1-->3-beta-glucan (zymosan)-activated macrophages.
The molecular details of 1-->3-beta-glucans, a fungal cell wall component, induced inflammatory responses are not well understood. In the present study, we conducted a systematic analysis of the molecular events leading to tumor necrosis factor (TNF)-alpha production after glucan stimulation of macrophages. We demonstrated that activation of nuclear factor kappaB (NF-kappaB) is essential in zymosan A (a source of 1-->3-beta-glucans)-induced TNF-alpha production in macrophages (RAW264.7 cells). Zymosan A-induced TNF-alpha protein production was associated with an increase in the TNF-alpha gene promoter activity. Activation of the TNF-alpha gene promoter was dependent on activation of NF-kappaB. Time course studies indicated that DNA binding activity of NF-kappaB preceded TNF-alpha promoter activity. Inhibition of NF-kappaB activation led to a dramatic reduction in both TNF-alpha promoter activity and TNF-alpha protein production in the response to zymosan A. Mutation of a major NF-kappaB binding site (kappa3) in the gene promoter resulted in a significant decrease in the induction of the gene promoter by zymosan A, while mutation of Egr or CRE sites failed to inhibit the response to zymosan. Together, these results strongly suggest that NF-kappaB is involved in signal transduction of 1-->3-beta-glucans-induced TNF-alpha expression.
Engineering Control and Technology Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, National Institutes of Health, Morgantown, West Virginia 26505, USA. syoung@cdc.gov
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Young
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Ye
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Frazer
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Shi
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Castranova
D000818:Animals; D001665:Binding Sites; D002460:Cell Line; D005936:Glucans / Q000378:metabolism*; D007700:Kinetics; D008262:Macrophage Activation / Q000187:drug effects*; D008264:Macrophages / Q000187:drug effects* / Q000378:metabolism; D051379:Mice; D016328:NF-kappa B / Q000037:antagonists & inhibitors; D011401:Promoter Regions, Genetic; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis* / Q000235:genetics; D015054:Zymosan / Q000494:pharmacology*; D047071:beta-Glucans
D005936:Glucans; D016328:NF-kappa B; D014409:Tumor Necrosis Factor-alpha; D047071:beta-Glucans; D015054:Zymosan; C033363:beta-1,3-glucan