Regulation of inducible nitric oxide synthase in proinflammatory cytokine-stimulated human primary astrocytes

Free Radic Biol Med. 2005 Mar 1;38(5):655-64. doi: 10.1016/j.freeradbiomed.2004.11.021.


The present study was undertaken to investigate the mechanism of expression of inducible nitric oxide synthase (iNOS) in human primary astrocytes. Among IL-1beta, TNF-alpha, and IFN-gamma, only IL-1beta alone was capable of inducing iNOS. Similarly, among different cytokine combinations, the combinations involving only IL-1beta as a partner were capable of inducing iNOS. The combination of IL-1beta and IFN-gamma (IL-IF) induced the expression of iNOS at the highest level. All three cytokines alone induced the activation of AP-1 while IL-1beta and TNF-alpha but not IFN-gamma induced the activation of NF-kappaB. However, among the three cytokines, only IL-1beta was capable of inducing the activation of CCAAT/enhancer-binding proteinbeta (C/EBPbeta), suggesting an essential role of C/EBPbeta in the expression of iNOS in astrocytes. Although IL-1beta and IFN-gamma alone induced the activation of AP-1, the combination of these two cytokines (IL-IF) markedly inhibited the activation of AP-1. Consistently, JNK-I, a specific inhibitor of JNK, inhibited IL-1beta-mediated activation of AP-1 and expression of iNOS. On the other hand, JNK-I had no effect on (IL-IF)-induced expression of iNOS, suggesting that the activation of AP-1 is involved only during the low level of iNOS induction by IL-1beta but not during the high level of induction by IL-IF. In contrast, the activation of gamma-activation site (GAS) was involved only during the high level of induction by IL-IF but not during the low level of induction by IL-1beta. However, the activation of NF-kappaB and C/EBPbeta was involved in the induction of iNOS by IL-1beta as well as by IL-IF.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Astrocytes / drug effects
  • Astrocytes / enzymology*
  • CCAAT-Enhancer-Binding Protein-beta / biosynthesis*
  • Cytokines / pharmacology*
  • Enzyme Induction
  • Gene Expression Regulation, Enzymologic
  • Humans
  • Interferon-gamma / pharmacology
  • Interleukin-1 / pharmacology
  • Interleukin-1beta
  • JNK Mitogen-Activated Protein Kinases / antagonists & inhibitors
  • Lipopolysaccharides / pharmacology
  • NF-kappa B / physiology
  • Nitric Oxide / biosynthesis
  • Nitric Oxide Synthase / biosynthesis*
  • Nitric Oxide Synthase Type II
  • Peptide Fragments / pharmacology
  • Promoter Regions, Genetic / physiology
  • Signal Transduction / physiology
  • Transcription Factor AP-1 / physiology
  • Tumor Necrosis Factor-alpha / pharmacology


  • CCAAT-Enhancer-Binding Protein-beta
  • Cytokines
  • Interleukin-1
  • Interleukin-1beta
  • Lipopolysaccharides
  • NF-kappa B
  • Peptide Fragments
  • Transcription Factor AP-1
  • Tumor Necrosis Factor-alpha
  • interleukin-1beta (163-171)
  • Nitric Oxide
  • Interferon-gamma
  • NOS2 protein, human
  • Nitric Oxide Synthase
  • Nitric Oxide Synthase Type II
  • JNK Mitogen-Activated Protein Kinases