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Oncogene. 1995 Jul 6;11(1):97-106.

Conserved kappa B element located downstream of the tumor necrosis factor alpha gene: distinct NF-kappa B binding pattern and enhancer activity in LPS activated murine macrophages.

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Biological Carcinogenesis and Development Program, National Cancer Institute-Frederick Cancer Research and Development Center, Maryland, 21702-1201, USA.


Transcriptional activation of various genes by lipopolysaccharide (LPS) is known to be mediated, at least in part, by the NF-kappa B/Rel family of transcription factors. We have identified a novel kappa B element located immediately downstream of the TNF-alpha gene that is conserved together with its flanking sequences across species lines and can act as an LPS-responsive enhancer for reporter gene constructs driven by the minimal TNF promoter. In extracts from activated murine macrophages and macrophage cell lines this element binds several non-canonical NF-kappa B/Rel complexes, in addition to p50 (NFKB1) homodimer and p50-p65 (NKFB1-RelA) heterodimer. Combination of high-resolution electrophoretic mobility shift assays (EMSA) with monospecific antibodies and u.v.-cross-linking indicates that the prominent slow migrating complex III contain p65 homodimer and c-Rel. The appearance of complex III in EMSA parallels the translocation of p65 and c-Rel into the nucleus and occurs shortly after LPS induction. Transfection experiments with reporter constructs driven by this kappa B element indicate strong inducibility by LPS and p65, moderate inducibility by c-Rel and repression by p50. Functional activity of sandwich TNF-CAT-TNF constructs further suggests that LPS-inducible transcriptional activation of the TNF gene in murine macrophages may be partly mediated by a downstream enhancer.

[Indexed for MEDLINE]

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