Role of mitogen-activated protein kinases in inducible nitric oxide synthase and TNFalpha expression in human fetal astrocytes

J Neuroimmunol. 2002 May;126(1-2):180-9. doi: 10.1016/s0165-5728(02)00055-3.


Astrocytes are important sources of proinflammatory mediators such as iNOS and TNFalpha in the diseased central nervous system. In previous studies, we showed that the cytokine IL-1 plays a critical role in the activation of human astrocytes to express TNFalpha and the inducible form of nitric oxide synthase (iNOS). In the present study, we have addressed the role of the MAP-kinase pathway in the signaling events leading to the induction of these genes. Treatment with SB203580, a specific inhibitor of p38 mitogen-activated protein kinases (MAPK), potently inhibited IL-1-mediated induction of iNOS and TNFalpha in cultures of human fetal astrocytes. In contrast, PD98059, an upstream inhibitor of the extracellular regulated kinase (ERK)1/2 pathway, had little or no effect. Interestingly, SB203580 reduced the mRNA expression for iNOS, TNFalpha, and IL-6, indicating inhibition prior to translation. Transfection of astrocytes with a dominant-negative Jun-NH(2)-terminal kinase (JNK) construct also reduced iNOS expression. Western blot analysis showed phosphorylated p38 and JNK in IL-1-activated astrocytes, and phosphorylated ERK in both resting and activated cells. Electrophoretic mobility shift assay (EMSA) showed that IL-1 induced NF-kappaB and AP-1 DNA complex formation in astrocytes, and that SB203580 inhibited AP-1 complex formation. Taken together, these results demonstrate the differential roles played by the three MAP kinases in human astrocyte inflammatory gene activation and point to a crucial function of p38 and JNK MAP kinases in IL-1-mediated astrocyte activation.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Astrocytes / cytology
  • Astrocytes / enzymology*
  • Astrocytes / immunology*
  • Cells, Cultured
  • Enzyme Inhibitors / pharmacology
  • Fetus / cytology
  • Flavonoids / pharmacology
  • Gene Expression Regulation, Enzymologic / drug effects
  • Gene Expression Regulation, Enzymologic / immunology
  • Humans
  • Imidazoles / pharmacology
  • Interleukin-1 / immunology
  • JNK Mitogen-Activated Protein Kinases*
  • MAP Kinase Kinase 4
  • Mitogen-Activated Protein Kinase Kinases / genetics
  • Mitogen-Activated Protein Kinase Kinases / metabolism
  • Mitogen-Activated Protein Kinases / metabolism*
  • NF-kappa B / metabolism
  • Nitric Oxide Synthase / biosynthesis*
  • Nitric Oxide Synthase / metabolism
  • Nitric Oxide Synthase Type II
  • Nitrites / metabolism
  • Phosphorylation
  • Pyridines / pharmacology
  • Transcription Factor AP-1 / metabolism
  • Transcriptional Activation
  • Transfection
  • Tumor Necrosis Factor-alpha / biosynthesis*
  • Tumor Necrosis Factor-alpha / metabolism
  • p38 Mitogen-Activated Protein Kinases


  • Enzyme Inhibitors
  • Flavonoids
  • Imidazoles
  • Interleukin-1
  • NF-kappa B
  • Nitrites
  • Pyridines
  • Transcription Factor AP-1
  • Tumor Necrosis Factor-alpha
  • NOS2 protein, human
  • Nitric Oxide Synthase
  • Nitric Oxide Synthase Type II
  • JNK Mitogen-Activated Protein Kinases
  • Mitogen-Activated Protein Kinases
  • p38 Mitogen-Activated Protein Kinases
  • MAP Kinase Kinase 4
  • Mitogen-Activated Protein Kinase Kinases
  • SB 203580
  • 2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one