title: Assembly defects induce oxidative stress in inherited mitochondrial complex I deficiency.
abstract: Complex I (CI) deficiency is the most common respiratory chain defect representing more than 30% of mitochondrial diseases. CI is an L-shaped multi-subunit complex with a peripheral arm protruding into the mitochondrial matrix and a membrane arm. CI sequentially assembled into main assembly intermediates: the P (pumping), Q (Quinone) and N (NADH dehydrogenase) modules. In this study, we analyzed 11 fibroblast cell lines derived from patients with inherited CI deficiency resulting from mutations in the nuclear or mitochondrial DNA and impacting these different modules. In patient cells carrying a mutation located in the matrix arm of CI, blue native-polyacrylamide gel electrophoresis (BN-PAGE) revealed a significant reduction of fully assembled CI enzyme and an accumulation of intermediates of the N module. In these cell lines with an assembly defect, NADH dehydrogenase activity was partly functional, even though CI was not fully assembled. We further demonstrated that this functional N module was responsible for ROS production through the reduced flavin mononucleotide. Due to the assembly defect, the FMN site was not re-oxidized leading to a significant oxidative stress in cell lines with an assembly defect. These findings not only highlight the relationship between CI assembly and oxidative stress, but also show the suitability of BN-PAGE analysis in evaluating the consequences of CI dysfunction. Moreover, these data suggest that the use of antioxidants may be particularly relevant for patients displaying a CI assembly defect.
authors.affiliation: Angers University, Angers, France; UMR CNRS 6214-INSERM U1083, Angers F-49000, France.
authors.forename: Géraldine
authors.initials: G
authors.lastname: Leman
authors.affiliation: Angers University, Angers, France; Biochemistry and Genetics Laboratory, CHU Angers, F-49000, France; UMR CNRS 6214-INSERM U1083, Angers F-49000, France.
authors.forename: Naïg
authors.initials: N
authors.lastname: Gueguen
authors.affiliation: Angers University, Angers, France; Biochemistry and Genetics Laboratory, CHU Angers, F-49000, France; UMR CNRS 6214-INSERM U1083, Angers F-49000, France.
authors.forename: Valérie
authors.initials: V
authors.lastname: Desquiret-Dumas
authors.affiliation: Angers University, Angers, France; UMR CNRS 6214-INSERM U1083, Angers F-49000, France.
authors.forename: Mariame Selma
authors.initials: MS
authors.lastname: Kane
authors.affiliation: Biochemistry and Genetics Laboratory, CHU Angers, F-49000, France.
authors.forename: Céline
authors.initials: C
authors.lastname: Wettervald
authors.affiliation: Biochemistry and Genetics Laboratory, CHU Angers, F-49000, France.
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Chupin
authors.affiliation: Angers University, Angers, France; UMR CNRS 6214-INSERM U1083, Angers F-49000, France.
authors.forename: Arnaud
authors.initials: A
authors.lastname: Chevrollier
authors.affiliation: Genetics Department, CHU Reims, 51092 Reims Cedex, France.
authors.forename: Anne-Sophie
authors.initials: AS
authors.lastname: Lebre
authors.affiliation: Genetics Laboratory, Necker-Enfants Malades Hospital, Paris, France.
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Bonnefont
authors.affiliation: Angers University, Angers, France; Biochemistry and Genetics Laboratory, CHU Angers, F-49000, France.
authors.forename: Magalie
authors.initials: M
authors.lastname: Barth
authors.affiliation: Angers University, Angers, France; Biochemistry and Genetics Laboratory, CHU Angers, F-49000, France; UMR CNRS 6214-INSERM U1083, Angers F-49000, France.
authors.forename: Patrizia
authors.initials: P
authors.lastname: Amati-Bonneau
authors.affiliation: Angers University, Angers, France; UMR CNRS 6214-INSERM U1083, Angers F-49000, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Verny
authors.affiliation: Angers University, Angers, France; UMR CNRS 6214-INSERM U1083, Angers F-49000, France.
authors.forename: Daniel
authors.initials: D
authors.lastname: Henrion
authors.affiliation: Angers University, Angers, France; Biochemistry and Genetics Laboratory, CHU Angers, F-49000, France; UMR CNRS 6214-INSERM U1083, Angers F-49000, France.
authors.forename: Dominique
authors.initials: D
authors.lastname: Bonneau
authors.affiliation: Angers University, Angers, France; Biochemistry and Genetics Laboratory, CHU Angers, F-49000, France; UMR CNRS 6214-INSERM U1083, Angers F-49000, France.
authors.forename: Pascal
authors.initials: P
authors.lastname: Reynier
authors.affiliation: Angers University, Angers, France; Biochemistry and Genetics Laboratory, CHU Angers, F-49000, France; UMR CNRS 6214-INSERM U1083, Angers F-49000, France. Electronic address: ViProcaccio@chu-angers.fr.
authors.forename: Vincent
authors.initials: V
authors.lastname: Procaccio
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D016022:Case-Control Studies; D002478:Cells, Cultured; D004272:DNA, Mitochondrial / Q000235:genetics; D042967:Electron Transport Complex I / Q000737:chemistry / Q000172:deficiency* / Q000235:genetics / Q000378:metabolism; D005347:Fibroblasts / Q000378:metabolism; D006801:Humans; D028361:Mitochondrial Diseases / Q000235:genetics / Q000378:metabolism*; D008958:Models, Molecular; D009154:Mutation; D018384:Oxidative Stress / Q000502:physiology*; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D004272:DNA, Mitochondrial; D017382:Reactive Oxygen Species; D000255:Adenosine Triphosphate; D042967:Electron Transport Complex I
keywords: Assembly defects; Complex I; FMN site; Mitochondria; Mitochondrial diseases; Oxidative stress