Cooperative interaction between hypoxia and lipopolysaccharide (LPS) in the activation of the inducible nitric oxide synthase (INOS) promoter

G. Melillo, L. S. Tavlor, A. Brook, G. W. Cox, L. Varesio

Research output: Contribution to journalArticlepeer-review

Abstract

We have recently reported that a hypoxia-responsive element (iNOS-HRE) is required for the synergistic activation of the iNOS promoter by hypoxia (1% oxygen) plus IFN-y. To investigate the role of hypoxic conditions in the LPS-dependent induction of iNOS expression, ANA-1 M were stimulated with sub-optimal concentrations of LPS (10 ng/ml) cultured in hypoxic or normoxic (20% oxygen) conditions. We found that hypoxia, although ineffective by itself, caused a significant increase in iNOS mRNA expression induced by LPS alone. ANA-1 M transiently transfected with a plasmid containing the fall-length iNOS promoter linked to a CAT reporter gene expressed significantly higher levels of CAT activity when stimulated with LPS plus hypoxia, versus LPS alone. Deletion of either the iNOS-HRE or the NF-KB consensus sequence from the full-length iNOS promoter caused a dramatic decrease (> 80%) of CAT expression induced by LPS plus hypoxia In contrast, iNOS promoter constructs deleted of the IFN-y-responsive region remained inducible by LPS plus hypoxia. These data demonstrate that hypoxia is a costimulus with LPS for the induction of iNOS expression and they suggest the existence of a cooperative interaction between iNOS-HRE and NF-KB in the regulation of iNOS transcription.

Original languageEnglish
JournalFASEB Journal
Volume10
Issue number6
Publication statusPublished - 1996

ASJC Scopus subject areas

  • Agricultural and Biological Sciences (miscellaneous)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Biochemistry
  • Cell Biology

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