Regulation of inducible nitric oxide synthase in proinflammatory cytokine-stimulated human primary astrocytes.
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.
Jana
Malabendu
M
Section of Neuroscience, Department of Oral Biology, University of Nebraska Medical Center, 40th and Holdrege, Lincoln, NE 68583, USA.
Anderson
Jamar A
JA
Saha
Ramendra N
RN
Liu
Xiaojuan
X
Pahan
Kalipada
K
D001253:Astrocytes / Q000187:drug effects / Q000201:enzymology*; D022782:CCAAT-Enhancer-Binding Protein-beta / Q000096:biosynthesis*; D016207:Cytokines / Q000494:pharmacology*; D004790:Enzyme Induction; D015971:Gene Expression Regulation, Enzymologic; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology; D007375:Interleukin-1 / Q000494:pharmacology; D053583:Interleukin-1beta; D048031:JNK Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors; D008070:Lipopolysaccharides / Q000494:pharmacology; D016328:NF-kappa B / Q000502:physiology; D009569:Nitric Oxide / Q000096:biosynthesis; D019001:Nitric Oxide Synthase / Q000096:biosynthesis*; D052247:Nitric Oxide Synthase Type II; D010446:Peptide Fragments / Q000494:pharmacology; D011401:Promoter Regions, Genetic / Q000502:physiology; D015398:Signal Transduction / Q000502:physiology; D018808:Transcription Factor AP-1 / Q000502:physiology; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D022782:CCAAT-Enhancer-Binding Protein-beta; D016207:Cytokines; D007375:Interleukin-1; D053583:Interleukin-1beta; D008070:Lipopolysaccharides; D016328:NF-kappa B; D010446:Peptide Fragments; D018808:Transcription Factor AP-1; D014409:Tumor Necrosis Factor-alpha; C052994:interleukin-1beta (163-171); D009569:Nitric Oxide; D007371:Interferon-gamma; C496319:NOS2 protein, human; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; D048031:JNK Mitogen-Activated Protein Kinases