title: NF-kappaB activation is required for C5a-induced interleukin-8 gene expression in mononuclear cells.
abstract: C5a, a potent peptide chemoattractant, stimulates interleukin-8 (IL-8) secretion from peripheral blood mononuclear cells (PBMC). Experiments were conducted to understand the mechanisms for C5a-induced IL-8 production, which was 14-fold greater than that in unstimulated cells by 2 hours. IL-8 secretion was accompanied by accumulation of IL-8 mRNA in the cytosol and by nuclear expression of a kappaB DNA binding activity within 30 minutes. AP-1 but not NF-IL-6 DNA binding activity was also detected in C5a-stimulated PBMC; however, its delayed expression (maximal at 4 hours) suggested a less important role in the rapid production of IL-8. The correlation between C5a-induced kappaB binding activity and IL-8 gene expression was examined in the RAW264.7 macrophage cells using reporter genes directed by the kappaB sequence from IkappaBalpha and IL-8 promoter regions. C5a-induced reporter gene expression was abolished by introducing mutations into the kappaB sites and by coexpression of a dominant negative IkappaBalpha construct resistant to agonist-induced phosphorylation. Pertussis toxin, which ADP-ribosylates the Gi proteins known to couple to the C5a receptor, produced minimal inhibition of C5a-induced IL-8 expression and had little effect on C5a-induced calcium mobilization in RAW264.7 cells. These results suggest that NF-kappaB activation is required for C5a-induced IL-8 gene expression and that this response is mediated primarily through a pertussis toxin-insensitive pathway.
authors.affiliation: Department of Immunology, The Scripps Research Institute, La Jolla, CA, USA.
authors.forename: M H
authors.initials: MH
authors.lastname: Hsu
authors.forename: M
authors.initials: M
authors.lastname: Wang
authors.forename: D D
authors.initials: DD
authors.lastname: Browning
authors.forename: N
authors.initials: N
authors.lastname: Mukaida
authors.forename: R D
authors.initials: RD
authors.lastname: Ye
mesh_terms: D000818:Animals; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D015936:Complement C5a / Q000276:immunology / Q000494:pharmacology*; D003600:Cytosol / Q000276:immunology; D005786:Gene Expression Regulation / Q000276:immunology*; D017930:Genes, Reporter; D006801:Humans; D016209:Interleukin-8 / Q000096:biosynthesis / Q000235:genetics*; D007700:Kinetics; D007963:Leukocytes, Mononuclear / Q000276:immunology*; D051379:Mice; D016328:NF-kappa B / Q000378:metabolism*; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000494:pharmacology; D018808:Transcription Factor AP-1 / Q000378:metabolism; D014158:Transcription, Genetic; D014162:Transfection
chemical_list: D016209:Interleukin-8; D016328:NF-kappa B; D011994:Recombinant Proteins; D018808:Transcription Factor AP-1; D015936:Complement C5a