Interleukin 1-induced cyclooxygenase and nitric oxide synthase gene expression in the rat dorsal root ganglia is modulated by antioxidants.
Interleukin 1beta induced both nitric oxide synthase 2 (NOS-2) and cyclooxygenase 2 (COX-2) gene expression in dorsal root ganglion explant culture with increased NOS-2 and COX-2 activities, and corresponding increases in the production of nitric oxide and prostaglandin E(2). The proinflammatory cytokine also increased 8-isoprostaglandin F(2alpha) concentration, an index of oxidant stress-mediated production of lipid hydroperoxides/reactive oxygen species. The signaling mechanisms by which interleukin 1beta regulates NOS-2 and COX-2 genes remain obscure. Reactive oxygen species play an important role in inflammatory processes as mediators of injury, and potentially as intracellular signaling molecules in interleukin 1beta-mediated regulation of gene expression. The effects of antioxidants that act by different mechanisms on interleukin 1beta-mediated NOS-2 and COX-2 gene expression were studied in rat dorsal root ganglion explants. The oxidant scavenger pyrrolidine dithiocarbamate abolished interleukin 1beta-induced NOS-2 mRNA accumulation and decreased nitric oxide production in a concentration-dependent manner, thus indicating that this antioxidant decreased either the transcription of NOS-2 gene or the stability of NOS-2 mRNA. In contrast, pyrrolidine dithiocarbamate significantly inhibited COX-2 gene expression at the posttranscriptional level, since pyrrolidine dithiocarbamate did not affect interleukin 1beta-induced COX-2 mRNA transcripts but inhibited COX-2 protein expression and prostaglandin E(2) production. Rotenone, another antioxidant that attenuates reactive oxygen species production by inhibiting the mitochondrial electron transport system, failed to inhibit interleukin 1beta-induced NOS-2 and COX-2 mRNA-encoding transcripts. However, rotenone inhibited NOS-2 and COX-2 proteins and associated nitric oxide and prostaglandin E(2) production, respectively, suggesting a posttranscriptional target for interleukin 1beta-mediated regulation of NOS-2 and COX-2 gene expression. Furthermore, both pyrrolidine dithiocarbamate and rotenone also decreased interleukin 1beta-induced 8-isoprostaglandin F(2alpha) production. These results indicate that not only transcriptional regulation, but also posttranscriptional events are involved in a redox-sensitive regulation of interleukin 1beta-induced NOS-2 and COX-2 gene expression in the dorsal root ganglia. Overall, interleukin 1beta-induced oxidant stress appears to regulate NOS-2 and COX-2 gene expression primarily at the level of protein translation. By implicating reactive oxygen species production in interleukin-1beta receptor-activated molecular signaling in the dorsal root ganglia, our data suggest a possible novel target for intervention in cytokine-mediated inflammatory processes.
Igwe
O J
OJ
University of Missouri-Kansas City, School of Pharmacy, Division of Pharmacology, M3-103, Medical School Building, 2411 Holmes Street, Kansas City, MO 64108-2792, USA. igweo@umkc.edu
Murray
J N
JN
Moolwaney
A S
AS
D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D015237:Dinoprost / Q000031:analogs & derivatives*; D015232:Dinoprostone / Q000096:biosynthesis; D028441:F2-Isoprostanes / Q000096:biosynthesis; D005727:Ganglia, Spinal / Q000201:enzymology*; D015870:Gene Expression / Q000187:drug effects*; D066298:In Vitro Techniques; D007375:Interleukin-1 / Q000494:pharmacology*; D009569:Nitric Oxide / Q000096:biosynthesis; D019001:Nitric Oxide Synthase / Q000235:genetics* / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II; D011451:Prostaglandin-Endoperoxide Synthases / Q000235:genetics* / Q000378:metabolism; D011759:Pyrrolidines / Q000494:pharmacology; D020871:RNA Stability / Q000187:drug effects; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D012402:Rotenone / Q000494:pharmacology; D013859:Thiocarbamates / Q000494:pharmacology
D000975:Antioxidants; D028441:F2-Isoprostanes; D007375:Interleukin-1; D011759:Pyrrolidines; D012333:RNA, Messenger; D013859:Thiocarbamates; D012402:Rotenone; C020972:pyrrolidine dithiocarbamic acid; C075750:8-epi-prostaglandin F2alpha; D009569:Nitric Oxide; D015237:Dinoprost; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496318:Nos2 protein, rat; D011451:Prostaglandin-Endoperoxide Synthases; D015232:Dinoprostone