UPSTREAM NFIL-6-LIKE SITE LOCATED WITHIN A DNASE-I HYPERSENSITIVITY REGION MEDIATES LPS-INDUCED TRANSCRIPTION OF THE MURINE INTERLEUKIN-1-BETA GENE

To define the cis-acting elements that regulate LPS-stimulated IL-1 be ta gene transcription, we analyzed the murine IL-1 beta gene by digest ion with DNase I. At least two hypersensitive sites were located betwe en 2200 and 2600 bp upstream of the transcription start site in mononu clear phagocytes, but not in an IL-1 nonproducing immature T cell line . Specific DNA sequences required for LPS induction of IL-1 beta gene expression were identified within the DNase I hypersensitive (DH) regi on using transfection of reporter constructs that contained portions o f the IL-1 beta 5'-flanking region. Two specific DNA sequences were ta rgets for nuclear factor binding as assessed with use of electrophoret ic mobility shift analysis (EMSA). One site contained a consensus sequ ence for NFIL-6 binding. Base substitutions within this NFIL-6 site re sulted in virtual elimination of LPS-induced IL-1 beta gene transcript ion. Introduction of multimers of the NFIL-6-like sequence immediately 5' to homologous or heterologous promoters conferred LPS-induced tran scription, indicating that this NFIL-6-like consensus site was a trans criptional activator. Anti-C/EBP beta (NFIL-6) and anti-C/EBP delta (N FIL-6 beta) Abs identified both of these proteins in complexes formed between the NFIL-6-like element and mononuclear cell nuclear extracts. C/EBP delta (NFIL-6 beta) was not detected in complexes utilizing ext racts from the IL-1 nonproducing T cell line. These data are consisten t with the requirement for C/EBP beta (NFIL-6) and C/EBP delta (NFIL-6 beta) in the activation of murine IL-1 beta gene expression by endoto xin.