Cytokine induction of inducible nitric oxide synthase in an oligodendrocyte cell line : Role of p38 mitogen-activated protein kinase activation

• Published in: Journal of neurochemistry 1999-02, Vol.72 (2), p.472-478
• Main Authors: BHAT, N. R, PEISHENG ZHANG, BHAT, A. N
• Format: Article
• Language: English
• Subjects: Animals; Biological and medical sciences; Calcium-Calmodulin-Dependent Protein Kinases - antagonists & inhibitors; Calcium-Calmodulin-Dependent Protein Kinases - metabolism; Cell Line; Culture Media - pharmacology; Cytokines - pharmacology; Cytotoxins - pharmacology; Enzyme Activation - physiology; Enzyme Inhibitors - pharmacology; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Enzymologic - drug effects; Imidazoles - pharmacology; Interferon-gamma - pharmacology; Interleukin-1 - pharmacology; Isolated neuron and nerve. Neuroglia; Mitogen-Activated Protein Kinases; NG-Nitroarginine Methyl Ester - pharmacology; Nitric Oxide - metabolism; Nitric Oxide Synthase - antagonists & inhibitors; Nitric Oxide Synthase - genetics; Nitric Oxide Synthase - metabolism; Nitric Oxide Synthase Type II; Oligodendroglia - cytology; Oligodendroglia - drug effects; Oligodendroglia - enzymology; p38 Mitogen-Activated Protein Kinases; Phosphorylation; Pyridines - pharmacology; RNA, Messenger - analysis; Tumor Necrosis Factor-alpha - pharmacology; Vertebrates: nervous system and sense organs
• ISSN: 0022-3042; 1471-4159
• DOI: 10.1046/j.1471-4159.1999.0720472.x

The induction of inducible nitric oxide synthase (iNOS) by proinflammatory cytokines was studied in an oligodendrocyte progenitor cell line in relation to mitogen-activated protein kinase (MAPK) activation and cytokine-mediated cytotoxicity. When introduced individually to cultures of CG4 cells, the cytokines, i.e., tumor necrosis factor-alpha (TNF alpha), interleukin-1 (IL-1), and interferon-gamma (IFN gamma), had either minimal (TNF alpha) or no (IL-1 and IFN gamma) detectable stimulatory effect on the production of nitric oxide. However, combinations of these factors, in particular, TNF alpha plus IFN gamma, elicited a strong enhancement of nitric oxide synthesis and, as revealed by western blot and RT-PCR analysis, the expression of iNOS. TNF alpha and IL-1 were able to activate p38 MAPK in a time- and dose-dependent manner and together showed a combinatorial effect. In contrast, IFN gamma neither activated on its own nor enhanced the activation of p38 MAPK in response to TNF alpha and IL-1. However, a specific inhibitor of p38 MAPK, i.e., SB203580, inhibited the induction of iNOS in cytokine combination-treated cells in a dose-dependent manner, thereby suggesting a role for the MAPK cascade in regulating the induction of iNOS gene expression in cytokine-treated cells. Blocking of nitric oxide production by an inhibitor of iNOS, i.e., nitro-L-arginine methyl ester, had a minimal protective effect against cytokine-mediated cytotoxicity that occurred before the elevation of nitric oxide levels, thereby indicating temporal and functional dissociation of nitric oxide production from cell killing.