title: A 28-kDa splice variant of NADPH oxidase-4 is nuclear-localized and involved in redox signaling in vascular cells.
abstract: OBJECTIVE
  Reactive oxygen species-generating nicotinamide adenine dinucleotide phosphate (NADPH)-oxidase proteins (Noxs) are involved in cell differentiation, migration, and apoptosis. Nox4 is unique among Noxs in being constitutively active, and its subcellular localization may therefore be particularly important. In this study, we identified and characterized a novel nuclear-localized 28-kDa splice variant of Nox4 in vascular cells.
  
  
  RESULTS
  Nox4 immunoreactivity was noted in the nucleus and nucleolus of vascular smooth muscle cells and multiple other cell types by confocal microscopy. Cell fractionation, sequence analyses, and siRNA studies indicated that the nuclear-localized Nox4 is a 28-kDa splice variant, Nox4D, which lacks putative transmembrane domains. Nox4D overexpression resulted in significant NADPH-dependent reactive oxygen species production as detected by several different methods and caused increased phosphorylation of extracellular-signal-regulated kinase1/2 and the nuclear transcription factor Elk-1. Overexpression of Nox4D could also induce DNA damage as assessed by γ-H2AX phosphorylation. These effects were inhibited by a single amino acid substitution in the Nox4D NADPH-binding region.
  
  
  CONCLUSIONS
  Nox4D is a nuclear-localized and functionally active splice variant of Nox4 that may have important pathophysiologic effects through modulation of nuclear signaling and DNA damage.
authors: King's College London British Heart Foundation Center of Excellence, 125 Coldharbour Lane, London SE5 9NU, United Kingdom.
authors: Narayana
authors: N
authors: Anilkumar
authors: Gorka
authors: G
authors: San Jose
authors: Iain
authors: I
authors: Sawyer
authors: Celio X C
authors: CX
authors: Santos
authors: Claire
authors: C
authors: Sand
authors: Alison C
authors: AC
authors: Brewer
authors: Derek
authors: D
authors: Warren
authors: Ajay M
authors: AM
authors: Shah
mesh_terms: D000818:Animals; D002467:Cell Nucleus / Q000201:enzymology*; D004249:DNA Damage; D004789:Enzyme Activation; D005347:Fibroblasts / Q000201:enzymology*; D005455:Fluorescent Antibody Technique; D057809:HEK293 Cells; D006657:Histones / Q000378:metabolism; D061307:Human Umbilical Vein Endothelial Cells / Q000201:enzymology*; D006801:Humans; D018613:Microscopy, Confocal; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D008970:Molecular Weight; D009131:Muscle, Smooth, Vascular / Q000201:enzymology*; D016297:Mutagenesis, Site-Directed; D032383:Myocytes, Cardiac / Q000201:enzymology*; D032389:Myocytes, Smooth Muscle / Q000201:enzymology*; D000074663:NADPH Oxidase 4; D019255:NADPH Oxidases / Q000235:genetics / Q000378:metabolism*; D010084:Oxidation-Reduction; D010766:Phosphorylation; D061251:Primary Cell Culture; D020033:Protein Isoforms; D034622:RNA Interference; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction; D014162:Transfection
chemical_list: C468783:H2AX protein, human; D006657:Histones; D020033:Protein Isoforms; D017382:Reactive Oxygen Species; D000074663:NADPH Oxidase 4; D019255:NADPH Oxidases; C498910:NOX4 protein, human; C422943:Nox4 protein, mouse; C498911:Nox4 protein, rat; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3