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

Liwei L. Hua, Meng Liang Zhao, Melissa Cosenza, Mee Ohk Kim, Huan Huang, Herbert B. Tanowitz, Celia F. Brosnan, Sunhee C. Lee

Research output: Contribution to journalArticle

90 Scopus citations

Abstract

Astrocytes are important sources of proinflammatory mediators such as iNOS and TNFα 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 TNFα 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 TNFα 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, TNFα, and IL-6, indicating inhibition prior to translation. Transfection of astrocytes with a dominant-negative Jun-NH2-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-κB 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.

Original languageEnglish (US)
Pages (from-to)180-189
Number of pages10
JournalJournal of Neuroimmunology
Volume126
Issue number1-2
DOIs
StatePublished - May 27 2002

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Keywords

  • Astrocytes
  • Kinase
  • Nitric oxide synthase

ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology
  • Neurology
  • Clinical Neurology

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