NF-kappaB is required for cytokine-induced manganese superoxide dismutase expression in insulin-producing cells

Reactive oxygen species play an important role in the cytotoxic effect of inflammatory cytokines on pancreatic beta-cells in type 1 diabetes mellitus. The antioxidant enzyme manganese superoxide dismutase (MnSOD) is part of the cellular defenses against these deleterious radicals. MnSOD gene express...

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Bibliographic Details
Published in:Endocrinology (Philadelphia) 2000-01, Vol.141 (1), p.153
Main Authors: Darville, M I, Ho, Y S, Eizirik, D L
Format: Article
Language:English
Subjects:
Animals
Base Sequence
Cells, Cultured
Cytokines - pharmacology
Electrophoresis
Flow Cytometry
Gene Expression Regulation, Enzymologic - drug effects
Gene Expression Regulation, Enzymologic - genetics
Insulin - biosynthesis
Interferon-gamma - physiology
Interleukin-1 - physiology
Introns - genetics
Islets of Langerhans - enzymology
Luciferases - metabolism
Molecular Sequence Data
Mutagenesis, Site-Directed - genetics
NF-kappa B - genetics
NF-kappa B - physiology
Plasmids - genetics
Promoter Regions, Genetic - genetics
Rats
Reverse Transcriptase Polymerase Chain Reaction
Superoxide Dismutase - biosynthesis
Superoxide Dismutase - genetics
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Summary:Reactive oxygen species play an important role in the cytotoxic effect of inflammatory cytokines on pancreatic beta-cells in type 1 diabetes mellitus. The antioxidant enzyme manganese superoxide dismutase (MnSOD) is part of the cellular defenses against these deleterious radicals. MnSOD gene expression is induced by cytokines in insulin-producing cells, but the transcriptional regulation of MnSOD expression in these cells is not well understood. In this report, we investigated the transcriptional regulation by cytokines of the rat MnSOD gene in insulin-producing cells. By transient transfections with promoter-luciferase reporter constructs, we identified two interleukin (IL)-1beta-responsive elements, conferring each an additive 3-fold IL-1beta-induced transcriptional activity. The first is located in the promoter region, whereas the second is located in the second intron of the MnSOD gene. Interestingly, the intronic element is required for interferon-gamma-induced potentiation. Site-directed mutagenesis and band-shift assays showed that an NF-kappaB binding site in each region is necessary, but not sufficient, for transcriptional induction by IL-1beta. Our results suggest that NF-kappaB may cooperate with CCAAT/enhancer-binding protein factors in the promoter region and with octamer and Ets factors in the intronic region.
ISSN:0013-7227