Cooperative interaction of nuclear factor-kappa B- and cis-regulatory enhancer binding protein-like factor binding elements in activating the interleukin-8 gene by pro-inflammatory cytokines

Abstract

A novel cytokine, interleukin-8 (IL-8), may play major roles in the inflammatory process by recruiting neutrophils and T cells into inflammatory sites. The production of this cytokine is not constitutive and is induced in a variety of cell types by stimulation with mitogens and cytokines. Among cytokines, only IL-1 and tumor necrosis factor (TNF) can induce IL-8 gene expression at the transcriptional level. Transfection of a human fibrosarcoma cell line with chloramphenicol acetyltransferase expression plasmids linked to a 5'-flanking deletion mutants of the IL-8 gene demonstrated that the nucleotides between -94 and -71 base pairs from the start of the first exon are essential and sufficient for the IL-8 induction by either IL-1, TNF, or phorbol 12-myristate 13-acetate. This sequence is composed of two cis-elements; one is the potential binding site for a nuclear factor-kappa B-like factor and the other for a cis-regulatory enhancer binding protein-like factor. Mutations in either elements abolished IL-1, TNF, and phorbol 12-myristate 13-acetate responsiveness. This report provides the first evidence that cooperation between two distinct cis-elements may be required for induction of gene expression by either IL-1 or TNF.