title: Nrf2 regulates ROS production by mitochondria and NADPH oxidase.
abstract: BACKGROUND
  Nuclear factor (erythroid-derived 2) factor 2 (Nrf2) is a crucial transcription factor mediating protection against oxidants. Nrf2 is negatively regulated by cytoplasmic Kelch-like ECH associated protein 1 (Keap1) thereby providing inducible antioxidant defence. Antioxidant properties of Nrf2 are thought to be mainly exerted by stimulating transcription of antioxidant proteins, whereas its effects on ROS production within the cell are uncertain.
  
  
  METHODS
  Live cell imaging and qPCR in brain hippocampal glio-neuronal cultures and explants slice cultures with graded expression of Nrf2, i.e. Nrf2-knockout (Nrf2-KO), wild-type (WT), and Keap1-knockdown (Keap1-KD).
  
  
  RESULTS
  We here show that ROS production in Nrf2-KO cells and tissues is increased compared to their WT counterparts. Mitochondrial ROS production is regulated by the Keap1-Nrf2 pathway by controlling mitochondrial bioenergetics. Surprisingly, Keap1-KD cells and tissues also showed higher rates of ROS production when compared to WT, although with a smaller magnitude. Analysis of the mRNA expression levels of the two NOX isoforms implicated in brain pathology showed, that NOX2 is dramatically upregulated under conditions of Nrf2 deficiency, whereas NOX4 is upregulated when Nrf2 is constitutively activated (Keap1-KD) to a degree which paralleled the increases in ROS production.
  
  
  CONCLUSIONS
  These observations suggest that the Keap1-Nrf2 pathway regulates both mitochondrial and cytosolic ROS production through NADPH oxidase.
  
  
  CONCLUSIONS
  Findings supports a key role of the Keap1-Nrf2 pathway in redox homeostasis within the cell.
authors.affiliation: UCL Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK; Department of Neurology, University of Muenster, Muenster, Germany.
authors.forename: Stjepana
authors.initials: S
authors.lastname: Kovac
authors.affiliation: UCL Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK.
authors.forename: Plamena R
authors.initials: PR
authors.lastname: Angelova
authors.affiliation: UCL Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK.
authors.forename: Kira M
authors.initials: KM
authors.lastname: Holmström
authors.affiliation: Jacqui Wood Cancer Centre, Division of Cancer Research, Ninewells Hospital and Medical School, University of Dundee, Dundee DD1 9SY, Scotland, UK.
authors.forename: Ying
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Departments of Pharmacology and Molecular Sciences and Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Departments of Pharmacology and Molecular Sciences and Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA. Electronic address: a.dinkovakostova@dundee.ac.uk.
authors.forename: Albena T
authors.initials: AT
authors.lastname: Dinkova-Kostova
authors.affiliation: UCL Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK. Electronic address: a.abramov@ucl.ac.uk.
authors.forename: Andrey Y
authors.initials: AY
authors.lastname: Abramov
mesh_terms: D000818:Animals; D003600:Cytosol / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins / Q000502:physiology; D000072019:Kelch-Like ECH-Associated Protein 1; D051379:Mice; D008812:Mice, Hairless; D008928:Mitochondria / Q000378:metabolism*; D019255:NADPH Oxidases / Q000502:physiology*; D051267:NF-E2-Related Factor 2 / Q000502:physiology*; D017382:Reactive Oxygen Species / Q000378:metabolism*
chemical_list: D047908:Intracellular Signaling Peptides and Proteins; C431364:KEAP1 protein, human; D000072019:Kelch-Like ECH-Associated Protein 1; D051267:NF-E2-Related Factor 2; C495636:Nfe2l2 protein, mouse; D017382:Reactive Oxygen Species; D019255:NADPH Oxidases
keywords: Keap1; NADPH oxidase; NOX; Nrf2; ROS