Modulation of inducible nitric oxide synthase by hypoxia in pulmonary artery endothelial cells

J. J. Zulueta, R. Sawhney, U. Kayyali, M. Fogel, C. Donaldson, H. Huang, J. J. Lanzillo, Paul M Hassoun

Research output: Contribution to journalArticle

Abstract

The effects of hypoxia on the regulation of inducible nitric oxide synthase (NOS) 2 expression were examined in cultured rat pulmonary microvascular endothelial cells (EC). EC did not express NOS 2 mRNA or protein when exposed to normoxia or hypoxia unless they were pretreated with interleukin (IL)-1β and/or tumor necrosis factor (TNF)-α for 24 h. Induction of NOS 2 by IL-1β+TNF-α was significantly attenuated by concomitant exposure of EC to hypoxia or treatment of EC with antioxidants such as tiron, diphenyliodonium, and catalase, suggesting that NOS 2 expression is dependent on the production of reactive oxygen species. Degradation of IκB and activation of NF-κB, which were both induced by treatment of EC with cytokines, were not altered when the cells were exposed to hypoxia, suggesting that the modulation of NOS 2 expression by hypoxia is unrelated to NF-κB activation. Following stimulation with IL-1β+TNF-α for 24 h, incubation of EC in normoxia resulted in a progressive decline in NOS 2 expression and a calculated half-life of approximately 6 h for NOS 2 mRNA. Hypoxia significantly prolonged the half-life of NOS 2 mRNA (17 h, P <0.05 versus normoxic EC). The half-life of NOS 2 mRNA was also prolonged by actinomycin D treatment (19.5 and 29.5 h for normoxic and hypoxic EC, respectively), suggesting that transcription of an RNA destabilizing factor or RNAse contributes to NOS 2 mRNA degradation. In EC transiently transfected with the rat NOS 2 promoter, hypoxia and the combination of IL-1β+TNF-α independently increased promoter activity 2.2- and 3-fold, respectively. As opposed to the attenuating effect that hypoxia had on IL-1β+TNF-α-dependent induction of NOS 2 gene expression, the concomitant treatment with IL-1β+TNF-α and hypoxia synergistically increased NOS 2 promoter activity 17.6-fold. Taken together, these results suggest that hypoxia alone does not induce NOS 2 expression in cultured pulmonary microvascular EC, but may modulate cytokine induction of this enzyme at pretranscriptional, transcriptional, and posttranscriptional levels.

Original languageEnglish (US)
Pages (from-to)22-30
Number of pages9
JournalAmerican Journal of Respiratory Cell and Molecular Biology
Volume26
Issue number1
StatePublished - 2002
Externally publishedYes

Fingerprint

Endothelial cells
Nitric Oxide Synthase Type II
Nitric Oxide Synthase
Pulmonary Artery
Endothelial Cells
Modulation
Interleukin-1
Tumor Necrosis Factor-alpha
Messenger RNA
Half-Life
Hypoxia
Rats
1,2-Dihydroxybenzene-3,5-Disulfonic Acid Disodium Salt
Chemical activation
Cytokines
Cell Hypoxia
Degradation
Lung
Enzyme Induction
RNA Stability

ASJC Scopus subject areas

  • Cell Biology
  • Molecular Biology
  • Pulmonary and Respiratory Medicine

Cite this

Modulation of inducible nitric oxide synthase by hypoxia in pulmonary artery endothelial cells. / Zulueta, J. J.; Sawhney, R.; Kayyali, U.; Fogel, M.; Donaldson, C.; Huang, H.; Lanzillo, J. J.; Hassoun, Paul M.

In: American Journal of Respiratory Cell and Molecular Biology, Vol. 26, No. 1, 2002, p. 22-30.

Research output: Contribution to journalArticle

Zulueta, JJ, Sawhney, R, Kayyali, U, Fogel, M, Donaldson, C, Huang, H, Lanzillo, JJ & Hassoun, PM 2002, 'Modulation of inducible nitric oxide synthase by hypoxia in pulmonary artery endothelial cells', American Journal of Respiratory Cell and Molecular Biology, vol. 26, no. 1, pp. 22-30.
Zulueta, J. J. ; Sawhney, R. ; Kayyali, U. ; Fogel, M. ; Donaldson, C. ; Huang, H. ; Lanzillo, J. J. ; Hassoun, Paul M. / Modulation of inducible nitric oxide synthase by hypoxia in pulmonary artery endothelial cells. In: American Journal of Respiratory Cell and Molecular Biology. 2002 ; Vol. 26, No. 1. pp. 22-30.
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AU - Huang, H.

AU - Lanzillo, J. J.

AU - Hassoun, Paul M

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