Oxidant-mediated increases in redox factor-1 nuclear protein and activator protein-1 DNA binding in asbestos-treated macrophages.
Alveolar macrophages have been implicated in the pathogenesis of a number of acute and chronic lung disorders. We have previously shown that normal human alveolar macrophages exhibit decreased DNA binding activity of the transcription factor, AP-1, compared with monocytes. Furthermore, this decrease in AP-1 DNA binding appears to be due to a decrease in the redox active protein, redox factor (Ref)-1. Ref-1 is an important redox regulator of a number of transcription factors, including NF-kappaB and AP-1. In this study we evaluated the role of asbestos, a prototypic model of chronic fibrotic lung disease, in Ref-1 expression and activity. We found that incubation with low concentrations of crocidolite asbestos (0.5-1.25 microg/cm(2)) resulted in an increase in nuclear Ref-1 protein after 5 min, with a persistent elevation in protein up to 24 h. Additionally, an increase in nuclear Ref-1 could be induced by treating the cells with an oxidant-generating stimulus (iron loading plus PMA) and inhibited by diphenyleneiodonium chloride, an inhibitor of NADPH oxidase. The asbestos-induced accumulation of nuclear Ref-1 was associated with an increase in AP-1 DNA binding activity. These findings suggest that an exposure associated with fibrotic lung disease, i.e., asbestos, modulates accumulation of nuclear Ref-1 in macrophages, and that this effect is mediated by an oxidant stimulus.
Flaherty
Dawn M
DM
Department of Internal Medicine, University of Iowa College of Medicine and Veterans Affairs Medical Center, Iowa City, IA 52243, USA. flahertydm@mail.medicine.uiowa.edu
Monick
Martha M
MM
Carter
A Brent
AB
Peterson
Michael W
MW
Hunninghake
Gary W
GW
D000818:Animals; D017638:Asbestos, Crocidolite / Q000633:toxicity*; D019757:Carbon-Oxygen Lyases / Q000096:biosynthesis*; D002460:Cell Line; D004247:DNA / Q000378:metabolism*; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase; D006801:Humans; D007501:Iron / Q000494:pharmacology; D016676:Macrophages, Alveolar / Q000187:drug effects* / Q000378:metabolism; D051379:Mice; D019255:NADPH Oxidases / Q000037:antagonists & inhibitors; D017382:Reactive Oxygen Species; D018808:Transcription Factor AP-1 / Q000378:metabolism*
D017382:Reactive Oxygen Species; D018808:Transcription Factor AP-1; D017638:Asbestos, Crocidolite; D004247:DNA; D007501:Iron; D019255:NADPH Oxidases; D019757:Carbon-Oxygen Lyases; C085108:APEX1 protein, human; C486216:Apex1 protein, mouse; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase