title: Complementation of mitochondrial electron transport chain by manipulation of the NAD+/NADH ratio.
abstract: A decline in electron transport chain (ETC) activity is associated with many human diseases. Although diminished mitochondrial adenosine triphosphate production is recognized as a source of pathology, the contribution of the associated reduction in the ratio of the amount of oxidized nicotinamide adenine dinucleotide (NAD(+)) to that of its reduced form (NADH) is less clear. We used a water-forming NADH oxidase from Lactobacillus brevis (LbNOX) as a genetic tool for inducing a compartment-specific increase of the NAD(+)/NADH ratio in human cells. We used LbNOX to demonstrate the dependence of key metabolic fluxes, gluconeogenesis, and signaling on the cytosolic or mitochondrial NAD(+)/NADH ratios. Expression of LbNOX in the cytosol or mitochondria ameliorated proliferative and metabolic defects caused by an impaired ETC. The results underscore the role of reductive stress in mitochondrial pathogenesis and demonstrate the utility of targeted LbNOX for direct, compartment-specific manipulation of redox state.
authors.affiliation: Howard Hughes Medical Institute and Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, USA. Department of Systems Biology, Harvard Medical School, Boston, MA, USA. Broad Institute, Cambridge, MA, USA.
authors.forename: Denis V
authors.initials: DV
authors.lastname: Titov
authors.affiliation: Howard Hughes Medical Institute and Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, USA. Department of Systems Biology, Harvard Medical School, Boston, MA, USA. Broad Institute, Cambridge, MA, USA.
authors.forename: Valentin
authors.initials: V
authors.lastname: Cracan
authors.affiliation: Howard Hughes Medical Institute and Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, USA. Division of Gastroenterology, Massachusetts General Hospital, Boston, MA, USA.
authors.forename: Russell P
authors.initials: RP
authors.lastname: Goodman
authors.affiliation: Howard Hughes Medical Institute and Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, USA.
authors.forename: Jun
authors.initials: J
authors.lastname: Peng
authors.affiliation: Howard Hughes Medical Institute and Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, USA. Broad Institute, Cambridge, MA, USA.
authors.forename: Zenon
authors.initials: Z
authors.lastname: Grabarek
authors.affiliation: Howard Hughes Medical Institute and Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, USA. Department of Systems Biology, Harvard Medical School, Boston, MA, USA. Broad Institute, Cambridge, MA, USA. vamsi@hms.harvard.edu.
authors.forename: Vamsi K
authors.initials: VK
authors.lastname: Mootha
mesh_terms: D002384:Catalysis; D003600:Cytosol / Q000201:enzymology; D004579:Electron Transport; D045222:Electron Transport Chain Complex Proteins / Q000235:genetics / Q000378:metabolism*; D005816:Genetic Complementation Test; D005943:Gluconeogenesis / Q000235:genetics*; D006367:HeLa Cells; D006801:Humans; D052196:Levilactobacillus brevis / Q000201:enzymology / Q000235:genetics; D008928:Mitochondria / Q000378:metabolism*; D028361:Mitochondrial Diseases / Q000201:enzymology / Q000235:genetics; D009097:Multienzyme Complexes / Q000235:genetics / Q000378:metabolism*; D009243:NAD / Q000378:metabolism*; D009247:NADH, NADPH Oxidoreductases / Q000235:genetics / Q000378:metabolism*; D010084:Oxidation-Reduction
chemical_list: D045222:Electron Transport Chain Complex Proteins; D009097:Multienzyme Complexes; D009243:NAD; C023107:NADH oxidase; D009247:NADH, NADPH Oxidoreductases