Inhibition of IFN-gamma-mediated inducible nitric oxide synthase induction by the peroxisome proliferator-activated receptor gamma agonist, 15-deoxy-delta 12,14-prostaglandin J2, involves inhibition of the upstream Janus kinase/STAT1 signaling pathway.
Peroxisome proliferator-activated receptor gamma (PPARgamma) ligands have been reported to exert anti-inflammatory activities in macrophages by competition for transcriptional coactivators with some transcriptional factors, including NF-kappaB. In the present study the influence of PPARgamma activators on IFN-gamma-elicited macrophage stimulation and signaling cascades was investigated. The results show that IFN-gamma-induced inducible NO synthase (iNOS) gene transcription, iNOS protein induction, and NO production are more sensitive to inhibition by 15-deoxy-Delta(12,14)-prostaglandin J(2) (15dPGJ(2)) than by the other two PPARgamma agonists, GW1929 and ciglitazone. Delayed addition of 15dPGJ(2) for 2 h resulted in reduced inhibition, suggesting action by 15dPGJ(2) on the upstream signaling cascades. Immunoblotting, DNA binding, and reporter gene assays consistently revealed the inhibitory ability of 15dPGJ(2), but not GW1929 or ciglitazone, on IFN-gamma-elicited signaling cascades, including tyrosine phosphorylation of Janus tyrosine protein kinase 2 and STAT1, DNA binding, and IFN regulatory factor-1 trans-activation of STAT1. These effects of 15dPGJ(2) were not abrogated by the PPARgamma antagonist, bisphenol A diglycidyl ether, indicating the PPARgamma-independent actions. 15dPGJ(2) also attenuated IL-6-induced tyrosine phosphorylation of STAT1 and STAT3 in Hep3B hepatoma cells. Consistent with the inhibitory effect of reactive oxygen species on STAT1 signaling, STAT1 inhibition by 15dPGJ(2) was abrogated by N-acetylcysteine, glutathione, superoxide dismutase, and catalase. Furthermore, 15dPGJ(2)-induced inhibition of STAT1 phosphorylation and NO production still occurred in the presence of peroxovanadate, ruling out the action mechanism of 15dPGJ(2) on tyrosine phosphatase. Taken together, for the first time in this study we demonstrate that 15dPGJ(2) can inhibit cytokine-stimulated Janus kinase 2-STAT signaling through a PPARgamma-independent, reactive oxygen species-dependent mechanism. These data provide a novel molecular mechanism of iNOS inhibition by 15dPGJ(2) and confirm its physiological role in anti-inflammation.
Chen
Ching-Wen
CW
Department of Pharmacology, College of Medicine, National Taiwan University, Taipei, Taiwan.
Chang
Ying-Hsin
YH
Tsi
Chin-Ju
CJ
Lin
Wan-Wan
WW
D000111:Acetylcysteine / Q000494:pharmacology; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000037:antagonists & inhibitors* / Q000096:biosynthesis / Q000378:metabolism / Q000502:physiology; D015536:Down-Regulation / Q000187:drug effects; D004790:Enzyme Induction / Q000187:drug effects / Q000502:physiology; D005978:Glutathione / Q000494:pharmacology; D019073:HT29 Cells; D006801:Humans; D050856:Interferon Regulatory Factor-1; D007371:Interferon-gamma / Q000037:antagonists & inhibitors / Q000502:physiology*; D015850:Interleukin-6 / Q000494:pharmacology; D053614:Janus Kinase 2; D051379:Mice; D009569:Nitric Oxide / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors* / Q000096:biosynthesis; D052247:Nitric Oxide Synthase Type II; D020675:Peroxisomes / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D010750:Phosphoproteins / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D010766:Phosphorylation / Q000187:drug effects; D015230:Prostaglandin D2 / Q000031:analogs & derivatives / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D017027:Protein Tyrosine Phosphatases / Q000502:physiology; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors* / Q000502:physiology; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D018160:Receptors, Cytoplasmic and Nuclear / Q000819:agonists*; D050794:STAT1 Transcription Factor; D050796:STAT3 Transcription Factor; D015398:Signal Transduction / Q000187:drug effects* / Q000502:physiology; D015534:Trans-Activators / Q000037:antagonists & inhibitors* / Q000378:metabolism / Q000502:physiology; D014157:Transcription Factors / Q000819:agonists* / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D014443:Tyrosine / Q000037:antagonists & inhibitors / Q000378:metabolism; D014638:Vanadates / Q000494:pharmacology; D000093242:Interleukin-6 Inhibitors
D000111:Acetylcysteine; D000975:Antioxidants; D004268:DNA-Binding Proteins; D005978:Glutathione; D050856:Interferon Regulatory Factor-1; D007371:Interferon-gamma; D015850:Interleukin-6; D053614:Janus Kinase 2; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; D010750:Phosphoproteins; D015230:Prostaglandin D2; D017027:Protein Tyrosine Phosphatases; D011505:Protein-Tyrosine Kinases; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; D018160:Receptors, Cytoplasmic and Nuclear; D050794:STAT1 Transcription Factor; D050796:STAT3 Transcription Factor; D015534:Trans-Activators; D014157:Transcription Factors; D014443:Tyrosine; D014638:Vanadates; D000093242:Interleukin-6 Inhibitors; C097240:15-deoxy-delta(12,14)-prostaglandin J2; C494257:IRF1 protein, human; C494258:Irf1 protein, mouse; C494079:STAT1 protein, human; C494086:STAT3 protein, human; C494080:Stat1 protein, mouse; C494087:Stat3 protein, mouse; C069276:peroxovanadate; C496319:NOS2 protein, human; C496317:Nos2 protein, mouse; C507924:JAK2 protein, human; C507926:Jak2 protein, mouse