Role of NF-kappaB in transcriptional regulation of the phagocyte NADPH oxidase by tumor necrosis factor-alpha.
Macrophages play an important role in the pathogenesis of chronic inflammatory disease. Activation of these phagocytes induces the production of proinflammatory cytokines, such as IL-1 and TNF-alpha and the generation of reactive oxygen species (ROS), such as superoxide anion (O2*-). Recently, we found that TNF-alpha treatment of human monocytic cells (MonoMac1) and isolated human monocytes resulted in up-regulation of the NADPH oxidase gene, neutrophil cytosolic factor 2 (NCF2). These results suggested that TNF-alpha, produced by activated macrophages, could serve as an autocrine/paracrine regulator of the oxidase, resulting in increased and/or prolonged production of O2*-. To gain a better understanding of the mechanisms involved in NADPH oxidase regulation by TNF-alpha, we evaluated transcriptional regulation of oxidase genes in MonoMac1 cells and human monocytes. We show that TNF-alpha-treated cells have increased levels of mRNA and up-regulated expression of NADPH oxidase subunits p47(phox), p67(phox), and gp91(phox), as well as increased oxidase activity. Pharmacological inhibitors of NF-kappaB activation blocked TNF-alpha-induced up-regulation of NCF1, NCF2, and CYBB message, which correlated with a reduction in expression of the corresponding oxidase proteins and decreased O2*- production. These data demonstrate that the increase in and/or maintenance of O2*- production in TNF-alpha-treated MonoMac1 cells and monocytes are a result, in part, of transcriptional up-regulation of three essential NADPH oxidase genes via the NF-kappaB pathway. This novel finding supports a model, whereby TNF-alpha-dependent activation of NF-kappaB up-regulates phagocyte NADPH oxidase activity, leading to enhanced ROS production and further NF-kappaB activation, potentially contributing to sustained oxidant production in chronic inflammation.
Gauss
Katherine A
KA
Department of Veterinary Molecular Biology, Montana State University, Bozeman, MT 59717, USA. kgauss@montana.edu
Nelson-Overton
Laura K
LK
Siemsen
Daniel W
DW
Gao
Ying
Y
DeLeo
Frank R
FR
Quinn
Mark T
MT
D002273:Carcinogens / Q000494:pharmacology; D002478:Cells, Cultured; D005434:Flow Cytometry; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology*; D006801:Humans; D015151:Immunoblotting; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism; D009000:Monocytes / Q000187:drug effects* / Q000378:metabolism; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases / Q000235:genetics* / Q000378:metabolism; D016328:NF-kappa B / Q000502:physiology*; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013481:Superoxides / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014158:Transcription, Genetic; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
D002273:Carcinogens; D008562:Membrane Glycoproteins; D016328:NF-kappa B; D010750:Phosphoproteins; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D014409:Tumor Necrosis Factor-alpha; C079789:neutrophil cytosol factor 67K; D013481:Superoxides; C056558:CYBB protein, human; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases; C060505:neutrophil cytosolic factor 1; D013755:Tetradecanoylphorbol Acetate