Transcriptional regulation of human inducible nitric oxide synthase gene in an intestinal epithelial cell line

Stephen C. Linn, Peter J. Morelli, Iris Edry, Sarah E. Cottongim, Csaba Szabó, Andrew L. Salzman

Research output: Contribution to journalArticlepeer-review

86 Scopus citations

Abstract

The inducible form of nitric oxide synthase (iNOS) is expressed during inflammation of the intestine and may contribute to tissue injury. We have examined iNOS transcriptional regulation in DLD-1 cells, a human intestinal epithelial line that produces large amounts of nitric oxide and iNOS mRNA in response to a combination of the proinflammatory cytokines interleukin-1β (IL-1β) and interferon-γ (IFN-γ). Levels of iNOS mRNA are extremely low in unstimulated DLD-1 cells but increase dramatically after cytokine treatment. Nuclear run-on analyses demonstrated that transcriptional activation, which accounts for a portion of this increase, is dependent on both IL-1β and IFN- γ and requires de novo protein synthesis. Transfection of DLD-1 cells with reporter constructs containing deletions of the iNOS promoter showed that sequences located between 8.7 and 10.7 kb upstream of the transcription initiation site are necessary for cytokine responsiveness. This region contains potential binding sites for several cytokine-induced transcription factors and was shown to function in either orientation when placed upstream of a basal iNOS promoter segment terminating at -1.1 kb. The extremely distal location of the cytokine-responsive region contrasts with the reported positions of elements involved in the regulation of iNOS transcription in other cell types. Our data also suggest that posttranscriptional events could play a significant role in regulating iNOS gene expression in human intestinal epithelia.

Original languageEnglish (US)
Pages (from-to)G1499-G1508
JournalAmerican Journal of Physiology - Gastrointestinal and Liver Physiology
Volume272
Issue number6 35-6
DOIs
StatePublished - Jun 1997
Externally publishedYes

Keywords

  • Gene regulation
  • Interferon-γ
  • Interleukin-1β

ASJC Scopus subject areas

  • Physiology
  • Hepatology
  • Gastroenterology
  • Physiology (medical)

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