Activation of interleukin-6 gene expression through the NF-kappa B transcription factor.
The promoter region of the interleukin-6 (IL-6) gene has a putative NF-kappa B-binding site. We found that a fragment of the IL-6 promoter containing the site specifically binds highly purified NF-kappa B protein and the NF-kappa B protein in nuclear extracts of phorbol ester-induced Jurkat cells. Mutations of the NF-kappa B site abolished complex formation with both purified NF-kappa B and the nuclear extract protein. Transient expression of chloramphenicol acetyltransferase (CAT) plasmids containing the IL-6 promoter revealed very little activity of the promoter in U-937 monocytic cells and in HeLa cells before stimulation. However, stimulation of U-937 and HeLa cells by inducers of NF-kappa B led to a dramatic increase in CAT activity. Mutations in the NF-kappa B-binding site abolished inducibility of IL-6 promoter-cat constructs in U-937 cells by lipopolysaccharide, tumor necrosis factor alpha, the double-stranded RNA poly(IC), or phytohemagglutinin and in HeLa cells by tumor necrosis factor alpha and drastically reduced but did not completely eliminate inducibility in HeLa cells stimulated by double-stranded RNA poly(IC) or phorbol 12-myristate 13-acetate. These results suggest that NF-kappa B is an important mediator for activation of the IL-6 gene by a variety of IL-6 inducers in both U-937 and HeLa cells and that alternative inducible enhancer elements contribute in a cell-specific manner to IL-6 gene induction. Because NF-kappa B is involved in the control of a variety of genes activated upon inflammation, NF-kappa B may play a central role in the inflammatory response to infection and tissue injury.
Libermann
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Whitehead Institute for Biomedical Research, Cambridge, Massachusetts 02142.
Baltimore
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D000595:Amino Acid Sequence; D001483:Base Sequence; D002460:Cell Line; D004252:DNA Mutational Analysis; D004268:DNA-Binding Proteins / Q000502:physiology*; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D015850:Interleukin-6 / Q000235:genetics*; D008969:Molecular Sequence Data; D016328:NF-kappa B; D011401:Promoter Regions, Genetic; D012045:Regulatory Sequences, Nucleic Acid; D015183:Restriction Mapping; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014157:Transcription Factors / Q000502:physiology*; D015533:Transcriptional Activation
D004268:DNA-Binding Proteins; D015850:Interleukin-6; D016328:NF-kappa B; D014157:Transcription Factors; D013755:Tetradecanoylphorbol Acetate