title: The metabolomic signature of Leber's hereditary optic neuropathy reveals endoplasmic reticulum stress.
abstract: Leber's hereditary optic neuropathy (MIM#535000), the commonest mitochondrial DNA-related disease, is caused by mutations affecting mitochondrial complex I. The clinical expression of the disorder, usually occurring in young adults, is typically characterized by subacute, usually sequential, bilateral visual loss, resulting from the degeneration of retinal ganglion cells. As the precise action of mitochondrial DNA mutations on the overall cell metabolism in Leber's hereditary optic neuropathy is unknown, we investigated the metabolomic profile of the disease. High performance liquid chromatography coupled with tandem mass spectrometry was used to quantify 188 metabolites in fibroblasts from 16 patients with Leber's hereditary optic neuropathy and eight healthy control subjects. Latent variable-based statistical methods were used to identify discriminating metabolites. One hundred and twenty-four of the metabolites were considered to be accurately quantified. A supervised orthogonal partial least squares discriminant analysis model separating patients with Leber's hereditary optic neuropathy from control subjects showed good predictive capability (Q 2cumulated = 0.57). Thirty-eight metabolites appeared to be the most significant variables, defining a Leber's hereditary optic neuropathy metabolic signature that revealed decreased concentrations of all proteinogenic amino acids, spermidine, putrescine, isovaleryl-carnitine, propionyl-carnitine and five sphingomyelin species, together with increased concentrations of 10 phosphatidylcholine species. This signature was not reproduced by the inhibition of complex I with rotenone or piericidin A in control fibroblasts. The importance of sphingomyelins and phosphatidylcholines in the Leber's hereditary optic neuropathy signature, together with the decreased amino acid pool, suggested an involvement of the endoplasmic reticulum. This was confirmed by the significantly increased phosphorylation of PERK and eIF2α, as well as the greater expression of C/EBP homologous protein and the increased XBP1 splicing, in fibroblasts from affected patients, all these changes being reversed by the endoplasmic reticulum stress inhibitor, TUDCA (tauroursodeoxycholic acid). Thus, our metabolomic analysis reveals a pharmacologically-reversible endoplasmic reticulum stress in complex I-related Leber's hereditary optic neuropathy fibroblasts, a finding that may open up new therapeutic perspectives for the treatment of Leber's hereditary optic neuropathy with endoplasmic reticulum-targeting drugs.
authors.affiliation: PREMMi / Pôle de Recherche et d'Enseignement en Médecine Mitochondriale, Institut MITOVASC, CNRS 6214, INSERM U1083, Université d'Angers, Angers, France.|Département de Biochimie et Génétique, Centre Hospitalier Universitaire, Angers, France.
authors.forename: Juan Manuel
authors.initials: JM
authors.lastname: Chao de la Barca
authors.affiliation: Département de Biochimie et Génétique, Centre Hospitalier Universitaire, Angers, France.|INSERM U 1063, Université d'Angers, Angers, France.
authors.forename: Gilles
authors.initials: G
authors.lastname: Simard
authors.affiliation: PREMMi / Pôle de Recherche et d'Enseignement en Médecine Mitochondriale, Institut MITOVASC, CNRS 6214, INSERM U1083, Université d'Angers, Angers, France.|Département de Biochimie et Génétique, Centre Hospitalier Universitaire, Angers, France.
authors.forename: Patrizia
authors.initials: P
authors.lastname: Amati-Bonneau
authors.affiliation: INSERM U 1063, Université d'Angers, Angers, France.
authors.forename: Zainab
authors.initials: Z
authors.lastname: Safiedeen
authors.affiliation: PREMMi / Pôle de Recherche et d'Enseignement en Médecine Mitochondriale, Institut MITOVASC, CNRS 6214, INSERM U1083, Université d'Angers, Angers, France.|Département de Biochimie et Génétique, Centre Hospitalier Universitaire, Angers, France.
authors.forename: Delphine
authors.initials: D
authors.lastname: Prunier-Mirebeau
authors.affiliation: PREMMi / Pôle de Recherche et d'Enseignement en Médecine Mitochondriale, Institut MITOVASC, CNRS 6214, INSERM U1083, Université d'Angers, Angers, France.|Département de Biochimie et Génétique, Centre Hospitalier Universitaire, Angers, France.
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Chupin
authors.affiliation: Département de Biochimie et Génétique, Centre Hospitalier Universitaire, Angers, France.
authors.forename: Cédric
authors.initials: C
authors.lastname: Gadras
authors.affiliation: Département de Biochimie et Génétique, Centre Hospitalier Universitaire, Angers, France.
authors.forename: Lydie
authors.initials: L
authors.lastname: Tessier
authors.affiliation: PREMMi / Pôle de Recherche et d'Enseignement en Médecine Mitochondriale, Institut MITOVASC, CNRS 6214, INSERM U1083, Université d'Angers, Angers, France.|Département de Biochimie et Génétique, Centre Hospitalier Universitaire, Angers, France.
authors.forename: Naïg
authors.initials: N
authors.lastname: Gueguen
authors.affiliation: PREMMi / Pôle de Recherche et d'Enseignement en Médecine Mitochondriale, Institut MITOVASC, CNRS 6214, INSERM U1083, Université d'Angers, Angers, France.
authors.forename: Arnaud
authors.initials: A
authors.lastname: Chevrollier
authors.affiliation: PREMMi / Pôle de Recherche et d'Enseignement en Médecine Mitochondriale, Institut MITOVASC, CNRS 6214, INSERM U1083, Université d'Angers, Angers, France.|Département de Biochimie et Génétique, Centre Hospitalier Universitaire, Angers, France.
authors.forename: Valérie
authors.initials: V
authors.lastname: Desquiret-Dumas
authors.affiliation: PREMMi / Pôle de Recherche et d'Enseignement en Médecine Mitochondriale, Institut MITOVASC, CNRS 6214, INSERM U1083, Université d'Angers, Angers, France.
authors.forename: Marc
authors.initials: M
authors.lastname: Ferré
authors.affiliation: PREMMi / Pôle de Recherche et d'Enseignement en Médecine Mitochondriale, Institut MITOVASC, CNRS 6214, INSERM U1083, Université d'Angers, Angers, France.|Département de Biochimie et Génétique, Centre Hospitalier Universitaire, Angers, France.
authors.forename: Céline
authors.initials: C
authors.lastname: Bris
authors.affiliation: PREMMi / Pôle de Recherche et d'Enseignement en Médecine Mitochondriale, Institut MITOVASC, CNRS 6214, INSERM U1083, Université d'Angers, Angers, France.
authors.forename: Judith
authors.initials: J
authors.lastname: Kouassi Nzoughet
authors.affiliation: PREMMi / Pôle de Recherche et d'Enseignement en Médecine Mitochondriale, Institut MITOVASC, CNRS 6214, INSERM U1083, Université d'Angers, Angers, France.
authors.forename: Cinzia
authors.initials: C
authors.lastname: Bocca
authors.affiliation: PREMMi / Pôle de Recherche et d'Enseignement en Médecine Mitochondriale, Institut MITOVASC, CNRS 6214, INSERM U1083, Université d'Angers, Angers, France.|Département d'Ophtalmologie, Centre Hospitalier Universitaire, Angers, France.
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Leruez
authors.affiliation: PREMMi / Pôle de Recherche et d'Enseignement en Médecine Mitochondriale, Institut MITOVASC, CNRS 6214, INSERM U1083, Université d'Angers, Angers, France.|Département de Neurologie, Centre Hospitalier Universitaire, Angers, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Verny
authors.affiliation: PREMMi / Pôle de Recherche et d'Enseignement en Médecine Mitochondriale, Institut MITOVASC, CNRS 6214, INSERM U1083, Université d'Angers, Angers, France.|Département d'Ophtalmologie, Centre Hospitalier Universitaire, Angers, France.|Singapore Eye Research Institute, Singapore National Eye Centre, Duke-NUS, Singapore.
authors.forename: Dan
authors.initials: D
authors.lastname: Miléa
authors.affiliation: PREMMi / Pôle de Recherche et d'Enseignement en Médecine Mitochondriale, Institut MITOVASC, CNRS 6214, INSERM U1083, Université d'Angers, Angers, France.|Département de Biochimie et Génétique, Centre Hospitalier Universitaire, Angers, France.
authors.forename: Dominique
authors.initials: D
authors.lastname: Bonneau
authors.affiliation: PREMMi / Pôle de Recherche et d'Enseignement en Médecine Mitochondriale, Institut MITOVASC, CNRS 6214, INSERM U1083, Université d'Angers, Angers, France.
authors.forename: Guy
authors.initials: G
authors.lastname: Lenaers
authors.affiliation: INSERM U 1063, Université d'Angers, Angers, France.
authors.forename: M Carmen
authors.initials: MC
authors.lastname: Martinez
authors.affiliation: PREMMi / Pôle de Recherche et d'Enseignement en Médecine Mitochondriale, Institut MITOVASC, CNRS 6214, INSERM U1083, Université d'Angers, Angers, France.|Département de Biochimie et Génétique, Centre Hospitalier Universitaire, Angers, France.
authors.forename: Vincent
authors.initials: V
authors.lastname: Procaccio
authors.affiliation: PREMMi / Pôle de Recherche et d'Enseignement en Médecine Mitochondriale, Institut MITOVASC, CNRS 6214, INSERM U1083, Université d'Angers, Angers, France.|Département de Biochimie et Génétique, Centre Hospitalier Universitaire, Angers, France.
authors.forename: Pascal
authors.initials: P
authors.lastname: Reynier
mesh_terms: D000328:Adult; D000368:Aged; D002478:Cells, Cultured; D015331:Cohort Studies; D004272:DNA, Mitochondrial / Q000235:genetics*; D042967:Electron Transport Complex I / Q000235:genetics / Q000378:metabolism*; D059865:Endoplasmic Reticulum Stress / Q000187:drug effects / Q000502:physiology*; D005260:Female; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D005786:Gene Expression Regulation / Q000187:drug effects / Q000235:genetics; D006801:Humans; D007306:Insecticides / Q000494:pharmacology; D008297:Male; D055432:Metabolomics / Q000379:methods; D008875:Middle Aged; D009154:Mutation / Q000235:genetics*; D029242:Optic Atrophy, Hereditary, Leber / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D011725:Pyridines / Q000494:pharmacology; D012402:Rotenone / Q000494:pharmacology; D055815:Young Adult
chemical_list: D004272:DNA, Mitochondrial; D007306:Insecticides; D011725:Pyridines; D012402:Rotenone; C100213:piericidin A; D042967:Electron Transport Complex I
keywords: Leber’s hereditary optic neuropathy; endoplasmic reticulum stress; metabolomics; mitochondria; mitochondrial DNA