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Sala D, Marchet S, Nanetti L, Legati A, Mariotti C, Lamantea E, Ghezzi D, Catania A, Lamperti C. A novel MT-ATP6 variant associated with complicated ataxia in two unrelated Italian patients: case report and functional studies. Orphanet J Rare Dis 2024; 19:200. [PMID: 38755691 PMCID: PMC11100036 DOI: 10.1186/s13023-024-03212-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2023] [Accepted: 05/09/2024] [Indexed: 05/18/2024] Open
Abstract
BACKGROUND MT-ATP6 is a mitochondrial gene which encodes for the intramembrane subunit 6 (or A) of the mitochondrial ATP synthase, also known asl complex V, which is involved in the last step of oxidative phosphorylation to produce cellular ATP through aerobic metabolism. Although classically associated with the NARP syndrome, recent evidence highlights an important role of MT-ATP6 pathogenic variants in complicated adult-onset ataxias. METHODS We describe two unrelated patients with adult-onset cerebellar ataxia associated with severe optic atrophy and mild cognitive impairment. Whole mitochondrial DNA sequencing was performed in both patients. We employed patients' primary fibroblasts and cytoplasmic hybrids (cybrids), generated from patients-derived cells, to assess the activity of respiratory chain complexes, oxygen consumption rate (OCR), ATP production and mitochondrial membrane potential. RESULTS In both patients, we identified the same novel m.8777 T > C variant in MT-ATP6 with variable heteroplasmy level in different tissues. We identifed an additional heteroplasmic novel variant in MT-ATP6, m.8879G > T, in the patients with the most severe phenotype. A significant reduction in complex V activity, OCR and ATP production was observed in cybrid clones homoplasmic for the m.8777 T > C variant, while no functional defect was detected in m.8879G > T homoplasmic clones. In addition, fibroblasts with high heteroplasmic levelsof m.8777 T > C variant showed hyperpolarization of mitochondrial membranes. CONCLUSIONS We describe a novel pathogenic mtDNA variant in MT-ATP6 associated with adult-onset ataxia, reinforcing the value of mtDNA screening within the diagnostic workflow of selected patients with late onset ataxias.
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Affiliation(s)
- Daniele Sala
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico Carlo Besta, 20126, Milan, Italy
| | - Silvia Marchet
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico Carlo Besta, 20126, Milan, Italy
| | - Lorenzo Nanetti
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico Carlo Besta, 20126, Milan, Italy
| | - Andrea Legati
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico Carlo Besta, 20126, Milan, Italy
| | - Caterina Mariotti
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico Carlo Besta, 20126, Milan, Italy
| | - Eleonora Lamantea
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico Carlo Besta, 20126, Milan, Italy
| | - Daniele Ghezzi
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico Carlo Besta, 20126, Milan, Italy
- Department of Pathophysiology and Transplantation (DEPT), University of Milan, 20122, Milan, Italy
| | - Alessia Catania
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico Carlo Besta, 20126, Milan, Italy
| | - Costanza Lamperti
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico Carlo Besta, 20126, Milan, Italy.
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Citrigno L, Qualtieri A, Cerantonio A, De Benedittis S, Gallo O, Di Palma G, Spadafora P, Cavalcanti F. Genomics landscape of mitochondrial DNA variations in patients from South Italy affected by mitochondriopathies. J Neurol Sci 2024; 457:122869. [PMID: 38215527 DOI: 10.1016/j.jns.2024.122869] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Revised: 12/20/2023] [Accepted: 01/04/2024] [Indexed: 01/14/2024]
Abstract
Mitochondrial DNA (mtDNA) is a 16,569 base pairs, double-stranded, circular molecule that contains 37 genes coding for 13 subunits of the respiratory chain plus 2 rRNAs and 22 tRNAs. Mutations in these genes have been identified in patients with a variety of disorders affecting every system in the body. The advent of next generation sequencing technologies has provided the possibility to perform the whole mitochondrial DNA sequencing, allowing the identification of disease-causing pathogenic variants in a single platform. In this study, the whole mtDNA of 100 patients from South Italy affected by mitochondrial diseases was analyzed by using an amplicon-based approach and then the enriched libraries were deeply sequenced on the ION Torrent platform (Thermofisher Scientific Waltham, MA, USA). After bioinformatics analysis and filtering, we were able to find 26 nonsynonymous variants with a MAF <1% that were associated with different pathological phenotypes, expanding the mutational spectrum of these diseases. Moreover, among the new mutations found, we have also analyzed the 3D structure of the MT-ATP6 A200T gene variation in order to confirm suspected functional alterations. This work brings light on new variants possibly associated with several mitochondriopathies in patients from South Italy and confirms that deep sequencing approach, compared to the standard methods, is a reliable and time-cost reducing strategy to detect all the variants present in the mitogenome, making the possibility to create a genomics landscape of mitochondrial DNA variations in human diseases.
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Affiliation(s)
- Luigi Citrigno
- Institute for Biomedical Research and Innovation (IRIB), Department of Biomedical Sciences, National Research Council (CNR), Mangone (CS), Italy.
| | - Antonio Qualtieri
- Institute for Biomedical Research and Innovation (IRIB), Department of Biomedical Sciences, National Research Council (CNR), Mangone (CS), Italy
| | - Annamaria Cerantonio
- Institute for Biomedical Research and Innovation (IRIB), Department of Biomedical Sciences, National Research Council (CNR), Mangone (CS), Italy
| | - Selene De Benedittis
- Institute for Biomedical Research and Innovation (IRIB), Department of Biomedical Sciences, National Research Council (CNR), Mangone (CS), Italy
| | - Olivier Gallo
- Institute for Biomedical Research and Innovation (IRIB), Department of Biomedical Sciences, National Research Council (CNR), Mangone (CS), Italy
| | - Gemma Di Palma
- Institute for Biomedical Research and Innovation (IRIB), Department of Biomedical Sciences, National Research Council (CNR), Mangone (CS), Italy
| | - Patrizia Spadafora
- Institute for Biomedical Research and Innovation (IRIB), Department of Biomedical Sciences, National Research Council (CNR), Mangone (CS), Italy
| | - Francesca Cavalcanti
- Institute for Biomedical Research and Innovation (IRIB), Department of Biomedical Sciences, National Research Council (CNR), Mangone (CS), Italy
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Nieto-Panqueva F, Rubalcava-Gracia D, Hamel PP, González-Halphen D. The constraints of allotopic expression. Mitochondrion 2023; 73:30-50. [PMID: 37739243 DOI: 10.1016/j.mito.2023.09.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Revised: 08/28/2023] [Accepted: 09/18/2023] [Indexed: 09/24/2023]
Abstract
Allotopic expression is the functional transfer of an organellar gene to the nucleus, followed by synthesis of the gene product in the cytosol and import into the appropriate organellar sub compartment. Here, we focus on mitochondrial genes encoding OXPHOS subunits that were naturally transferred to the nucleus, and critically review experimental evidence that claim their allotopic expression. We emphasize aspects that may have been overlooked before, i.e., when modifying a mitochondrial gene for allotopic expression━besides adapting the codon usage and including sequences encoding mitochondrial targeting signals━three additional constraints should be considered: (i) the average apparent free energy of membrane insertion (μΔGapp) of the transmembrane stretches (TMS) in proteins earmarked for the inner mitochondrial membrane, (ii) the final, functional topology attained by each membrane-bound OXPHOS subunit; and (iii) the defined mechanism by which the protein translocator TIM23 sorts cytosol-synthesized precursors. The mechanistic constraints imposed by TIM23 dictate the operation of two pathways through which alpha-helices in TMS are sorted, that eventually determine the final topology of membrane proteins. We used the biological hydrophobicity scale to assign an average apparent free energy of membrane insertion (μΔGapp) and a "traffic light" color code to all TMS of OXPHOS membrane proteins, thereby predicting which are more likely to be internalized into mitochondria if allotopically produced. We propose that the design of proteins for allotopic expression must make allowance for μΔGapp maximization of highly hydrophobic TMS in polypeptides whose corresponding genes have not been transferred to the nucleus in some organisms.
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Affiliation(s)
- Felipe Nieto-Panqueva
- Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Diana Rubalcava-Gracia
- Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico; Division of Molecular Metabolism, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Patrice P Hamel
- Department of Molecular Genetics and Department of Biological Chemistry and Pharmacology, Ohio State University, Columbus, OH, USA; Vellore Institute of Technology (VIT), School of BioScience and Technology, Vellore, Tamil Nadu, India
| | - Diego González-Halphen
- Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico.
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Magistrati M, Gilea AI, Gerra MC, Baruffini E, Dallabona C. Drug Drop Test: How to Quickly Identify Potential Therapeutic Compounds for Mitochondrial Diseases Using Yeast Saccharomyces cerevisiae. Int J Mol Sci 2023; 24:10696. [PMID: 37445873 DOI: 10.3390/ijms241310696] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Revised: 06/22/2023] [Accepted: 06/25/2023] [Indexed: 07/15/2023] Open
Abstract
Mitochondrial diseases (MDs) refer to a group of clinically and genetically heterogeneous pathologies characterized by defective mitochondrial function and energy production. Unfortunately, there is no effective treatment for most MDs, and current therapeutic management is limited to relieving symptoms. The yeast Saccharomyces cerevisiae has been efficiently used as a model organism to study mitochondria-related disorders thanks to its easy manipulation and well-known mitochondrial biogenesis and metabolism. It has been successfully exploited both to validate alleged pathogenic variants identified in patients and to discover potential beneficial molecules for their treatment. The so-called "drug drop test", a phenotype-based high-throughput screening, especially if coupled with a drug repurposing approach, allows the identification of molecules with high translational potential in a cost-effective and time-saving manner. In addition to drug identification, S. cerevisiae can be used to point out the drug's target or pathway. To date, drug drop tests have been successfully carried out for a variety of disease models, leading to very promising results. The most relevant aspect is that studies on more complex model organisms confirmed the effectiveness of the drugs, strengthening the results obtained in yeast and demonstrating the usefulness of this screening as a novel approach to revealing new therapeutic molecules for MDs.
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Affiliation(s)
- Martina Magistrati
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, Parco Area delle Scienze 11/A, 43124 Parma, Italy
| | - Alexandru Ionut Gilea
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, Parco Area delle Scienze 11/A, 43124 Parma, Italy
| | - Maria Carla Gerra
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, Parco Area delle Scienze 11/A, 43124 Parma, Italy
| | - Enrico Baruffini
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, Parco Area delle Scienze 11/A, 43124 Parma, Italy
| | - Cristina Dallabona
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, Parco Area delle Scienze 11/A, 43124 Parma, Italy
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Tragni V, Primiano G, Tummolo A, Cafferati Beltrame L, La Piana G, Sgobba MN, Cavalluzzi MM, Paterno G, Gorgoglione R, Volpicella M, Guerra L, Marzulli D, Servidei S, De Grassi A, Petrosillo G, Lentini G, Pierri CL. Personalized Medicine in Mitochondrial Health and Disease: Molecular Basis of Therapeutic Approaches Based on Nutritional Supplements and Their Analogs. Molecules 2022; 27:3494. [PMID: 35684429 PMCID: PMC9182050 DOI: 10.3390/molecules27113494] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2022] [Revised: 05/24/2022] [Accepted: 05/26/2022] [Indexed: 01/03/2023] Open
Abstract
Mitochondrial diseases (MDs) may result from mutations affecting nuclear or mitochondrial genes, encoding mitochondrial proteins, or non-protein-coding mitochondrial RNA. Despite the great variability of affected genes, in the most severe cases, a neuromuscular and neurodegenerative phenotype is observed, and no specific therapy exists for a complete recovery from the disease. The most used treatments are symptomatic and based on the administration of antioxidant cocktails combined with antiepileptic/antipsychotic drugs and supportive therapy for multiorgan involvement. Nevertheless, the real utility of antioxidant cocktail treatments for patients affected by MDs still needs to be scientifically demonstrated. Unfortunately, clinical trials for antioxidant therapies using α-tocopherol, ascorbate, glutathione, riboflavin, niacin, acetyl-carnitine and coenzyme Q have met a limited success. Indeed, it would be expected that the employed antioxidants can only be effective if they are able to target the specific mechanism, i.e., involving the central and peripheral nervous system, responsible for the clinical manifestations of the disease. Noteworthily, very often the phenotypes characterizing MD patients are associated with mutations in proteins whose function does not depend on specific cofactors. Conversely, the administration of the antioxidant cocktails might determine the suppression of endogenous oxidants resulting in deleterious effects on cell viability and/or toxicity for patients. In order to avoid toxicity effects and before administering the antioxidant therapy, it might be useful to ascertain the blood serum levels of antioxidants and cofactors to be administered in MD patients. It would be also worthwhile to check the localization of mutations affecting proteins whose function should depend (less or more directly) on the cofactors to be administered, for estimating the real need and predicting the success of the proposed cofactor/antioxidant-based therapy.
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Affiliation(s)
- Vincenzo Tragni
- Department of Biosciences, Biotechnologies, Biopharmaceutics, University of Bari Aldo Moro, Via E. Orabona, 4, 70125 Bari, Italy; (V.T.); (L.C.B.); (G.L.P.); (M.N.S.); (R.G.); (M.V.); (L.G.); (A.D.G.)
- Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies (IBIOM), National Research Council (CNR), 70126 Bari, Italy;
| | - Guido Primiano
- Fondazione Policlinico Universitario A. Gemelli IRCCS, 00168 Rome, Italy; (G.P.); (S.S.)
- Dipartimento Universitario di Neuroscienze, Università Cattolica del Sacro Cuore, 00168 Rome, Italy
| | - Albina Tummolo
- Department of Metabolic Diseases, Clinical Genetics and Diabetology, Giovanni XXIII Children Hospital, Azienda Ospedaliero-Universitaria Consorziale, Via Amendola 207, 70126 Bari, Italy; (A.T.); (G.P.)
| | - Lucas Cafferati Beltrame
- Department of Biosciences, Biotechnologies, Biopharmaceutics, University of Bari Aldo Moro, Via E. Orabona, 4, 70125 Bari, Italy; (V.T.); (L.C.B.); (G.L.P.); (M.N.S.); (R.G.); (M.V.); (L.G.); (A.D.G.)
| | - Gianluigi La Piana
- Department of Biosciences, Biotechnologies, Biopharmaceutics, University of Bari Aldo Moro, Via E. Orabona, 4, 70125 Bari, Italy; (V.T.); (L.C.B.); (G.L.P.); (M.N.S.); (R.G.); (M.V.); (L.G.); (A.D.G.)
| | - Maria Noemi Sgobba
- Department of Biosciences, Biotechnologies, Biopharmaceutics, University of Bari Aldo Moro, Via E. Orabona, 4, 70125 Bari, Italy; (V.T.); (L.C.B.); (G.L.P.); (M.N.S.); (R.G.); (M.V.); (L.G.); (A.D.G.)
| | - Maria Maddalena Cavalluzzi
- Department of Pharmacy—Pharmaceutical Sciences, University of Bari Aldo Moro, Via E. Orabona 4, 70125 Bari, Italy;
| | - Giulia Paterno
- Department of Metabolic Diseases, Clinical Genetics and Diabetology, Giovanni XXIII Children Hospital, Azienda Ospedaliero-Universitaria Consorziale, Via Amendola 207, 70126 Bari, Italy; (A.T.); (G.P.)
| | - Ruggiero Gorgoglione
- Department of Biosciences, Biotechnologies, Biopharmaceutics, University of Bari Aldo Moro, Via E. Orabona, 4, 70125 Bari, Italy; (V.T.); (L.C.B.); (G.L.P.); (M.N.S.); (R.G.); (M.V.); (L.G.); (A.D.G.)
| | - Mariateresa Volpicella
- Department of Biosciences, Biotechnologies, Biopharmaceutics, University of Bari Aldo Moro, Via E. Orabona, 4, 70125 Bari, Italy; (V.T.); (L.C.B.); (G.L.P.); (M.N.S.); (R.G.); (M.V.); (L.G.); (A.D.G.)
| | - Lorenzo Guerra
- Department of Biosciences, Biotechnologies, Biopharmaceutics, University of Bari Aldo Moro, Via E. Orabona, 4, 70125 Bari, Italy; (V.T.); (L.C.B.); (G.L.P.); (M.N.S.); (R.G.); (M.V.); (L.G.); (A.D.G.)
| | - Domenico Marzulli
- Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies (IBIOM), National Research Council (CNR), 70126 Bari, Italy;
| | - Serenella Servidei
- Fondazione Policlinico Universitario A. Gemelli IRCCS, 00168 Rome, Italy; (G.P.); (S.S.)
- Dipartimento Universitario di Neuroscienze, Università Cattolica del Sacro Cuore, 00168 Rome, Italy
| | - Anna De Grassi
- Department of Biosciences, Biotechnologies, Biopharmaceutics, University of Bari Aldo Moro, Via E. Orabona, 4, 70125 Bari, Italy; (V.T.); (L.C.B.); (G.L.P.); (M.N.S.); (R.G.); (M.V.); (L.G.); (A.D.G.)
| | - Giuseppe Petrosillo
- Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies (IBIOM), National Research Council (CNR), 70126 Bari, Italy;
| | - Giovanni Lentini
- Department of Pharmacy—Pharmaceutical Sciences, University of Bari Aldo Moro, Via E. Orabona 4, 70125 Bari, Italy;
| | - Ciro Leonardo Pierri
- Department of Biosciences, Biotechnologies, Biopharmaceutics, University of Bari Aldo Moro, Via E. Orabona, 4, 70125 Bari, Italy; (V.T.); (L.C.B.); (G.L.P.); (M.N.S.); (R.G.); (M.V.); (L.G.); (A.D.G.)
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6
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Matuz-Mares D, González-Andrade M, Araiza-Villanueva MG, Vilchis-Landeros MM, Vázquez-Meza H. Mitochondrial Calcium: Effects of Its Imbalance in Disease. Antioxidants (Basel) 2022; 11:antiox11050801. [PMID: 35624667 PMCID: PMC9138001 DOI: 10.3390/antiox11050801] [Citation(s) in RCA: 32] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 04/17/2022] [Accepted: 04/19/2022] [Indexed: 02/06/2023] Open
Abstract
Calcium is used in many cellular processes and is maintained within the cell as free calcium at low concentrations (approximately 100 nM), compared with extracellular (millimolar) concentrations, to avoid adverse effects such as phosphate precipitation. For this reason, cells have adapted buffering strategies by compartmentalizing calcium into mitochondria and the endoplasmic reticulum (ER). In mitochondria, the calcium concentration is in the millimolar range, as it is in the ER. Mitochondria actively contribute to buffering cellular calcium, but if matrix calcium increases beyond physiological demands, it can promote the opening of the mitochondrial permeability transition pore (mPTP) and, consequently, trigger apoptotic or necrotic cell death. The pathophysiological implications of mPTP opening in ischemia-reperfusion, liver, muscle, and lysosomal storage diseases, as well as those affecting the central nervous system, for example, Parkinson’s disease (PD), Alzheimer’s disease (AD), Huntington’s disease (HD), and amyotrophic lateral sclerosis (ALS) have been reported. In this review, we present an updated overview of the main cellular mechanisms of mitochondrial calcium regulation. We specially focus on neurodegenerative diseases related to imbalances in calcium homeostasis and summarize some proposed therapies studied to attenuate these diseases.
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Affiliation(s)
- Deyamira Matuz-Mares
- Departamento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México, Avenida Universidad 3000, Cd. Universitaria, Coyoacán, Ciudad de México 04510, Mexico; (D.M.-M.); (M.G.-A.); (M.M.V.-L.)
| | - Martin González-Andrade
- Departamento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México, Avenida Universidad 3000, Cd. Universitaria, Coyoacán, Ciudad de México 04510, Mexico; (D.M.-M.); (M.G.-A.); (M.M.V.-L.)
| | | | - María Magdalena Vilchis-Landeros
- Departamento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México, Avenida Universidad 3000, Cd. Universitaria, Coyoacán, Ciudad de México 04510, Mexico; (D.M.-M.); (M.G.-A.); (M.M.V.-L.)
| | - Héctor Vázquez-Meza
- Departamento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México, Avenida Universidad 3000, Cd. Universitaria, Coyoacán, Ciudad de México 04510, Mexico; (D.M.-M.); (M.G.-A.); (M.M.V.-L.)
- Correspondence: ; Tel.: +52-55-5623-2168
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Use of Next-Generation Sequencing for Identifying Mitochondrial Disorders. Curr Issues Mol Biol 2022; 44:1127-1148. [PMID: 35723297 PMCID: PMC8947152 DOI: 10.3390/cimb44030074] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Revised: 02/18/2022] [Accepted: 02/24/2022] [Indexed: 12/06/2022] Open
Abstract
Mitochondria are major contributors to ATP synthesis, generating more than 90% of the total cellular energy production through oxidative phosphorylation (OXPHOS): metabolite oxidation, such as the β-oxidation of fatty acids, and the Krebs’s cycle. OXPHOS inadequacy due to large genetic lesions in mitochondrial as well as nuclear genes and homo- or heteroplasmic point mutations in mitochondrially encoded genes is a characteristic of heterogeneous, maternally inherited genetic disorders known as mitochondrial disorders that affect multisystemic tissues and organs with high energy requirements, resulting in various signs and symptoms. Several traditional diagnostic approaches, including magnetic resonance imaging of the brain, cardiac testing, biochemical screening, variable heteroplasmy genetic testing, identifying clinical features, and skeletal muscle biopsies, are associated with increased risks, high costs, a high degree of false-positive or false-negative results, or a lack of precision, which limits their diagnostic abilities for mitochondrial disorders. Variable heteroplasmy levels, mtDNA depletion, and the identification of pathogenic variants can be detected through genetic sequencing, including the gold standard Sanger sequencing. However, sequencing can be time consuming, and Sanger sequencing can result in the missed recognition of larger structural variations such as CNVs or copy-number variations. Although each sequencing method has its own limitations, genetic sequencing can be an alternative to traditional diagnostic methods. The ever-growing roster of possible mutations has led to the development of next-generation sequencing (NGS). The enhancement of NGS methods can offer a precise diagnosis of the mitochondrial disorder within a short period at a reasonable expense for both research and clinical applications.
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Miliotou AN, Pappas IS, Spyroulias G, Vlachaki E, Tsiftsoglou AS, Vizirianakis IS, Papadopoulou LC. Development of a novel PTD-mediated IVT-mRNA delivery platform for potential protein replacement therapy of metabolic/genetic disorders. MOLECULAR THERAPY. NUCLEIC ACIDS 2021; 26:694-710. [PMID: 34703653 PMCID: PMC8517095 DOI: 10.1016/j.omtn.2021.09.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/10/2020] [Accepted: 09/09/2021] [Indexed: 12/22/2022]
Abstract
The potential clinical applications of the powerful in vitro-transcribed (IVT)-mRNAs, to restore defective protein functions, strongly depend on their successful intracellular delivery and transient translation through the development of safe and efficient delivery platforms. In this study, an innovative (international patent-pending) methodology was developed, combining the IVT-mRNAs with the protein transduction domain (PTD) technology, as an efficient delivery platform. Based on the PTD technology, which enables the intracellular delivery of various cargoes intracellularly, successful conjugation of a PTD to the IVT-mRNAs was achieved and evaluated by band-shift assay and NMR spectroscopy. In addition, the PTD-IVT-mRNAs were applied and evaluated in two protein-disease models, including the mitochondrial disorder fatal infantile cardioencephalomyopathy and cytochrome c oxidase (COX) deficiency (attributed to SCO2 gene mutations) and β-thalassemia. The PTD-IVT-mRNA of SCO2 was successfully transduced and translated to the corresponding Sco2 protein inside the primary fibroblasts of a SCO2/COX-deficient patient, whereas the PTD-IVT-mRNA of β-globin was transduced and translated in bone marrow cells, derived from three β-thalassemic patients. The transducibility and the structural stability of the PDT-IVT-mRNAs, in both cases, were confirmed at the RNA and protein levels. We propose that our novel delivery platform could be clinically applicable as a protein therapy for metabolic/genetic disorders.
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Affiliation(s)
- Androulla N Miliotou
- Laboratory of Pharmacology, School of Pharmacy, Faculty of Health Sciences, Aristotle University of Thessaloniki, Thessaloniki, 546 42 Macedonia, Greece
| | - Ioannis S Pappas
- Laboratory of Pharmacology and Toxicology, Faculty of Veterinary Science, University of Thessaly, Karditsa, 431 00 Thessaly, Greece
| | | | - Efthimia Vlachaki
- Adult Thalassemia Unit, Hippokrateion General Hospital, Thessaloniki, 546 42 Macedonia, Greece
| | - Asterios S Tsiftsoglou
- Laboratory of Pharmacology, School of Pharmacy, Faculty of Health Sciences, Aristotle University of Thessaloniki, Thessaloniki, 546 42 Macedonia, Greece
| | - Ioannis S Vizirianakis
- Laboratory of Pharmacology, School of Pharmacy, Faculty of Health Sciences, Aristotle University of Thessaloniki, Thessaloniki, 546 42 Macedonia, Greece.,Department of Life and Health Sciences, University of Nicosia, 1700 Nicosia, Cyprus
| | - Lefkothea C Papadopoulou
- Laboratory of Pharmacology, School of Pharmacy, Faculty of Health Sciences, Aristotle University of Thessaloniki, Thessaloniki, 546 42 Macedonia, Greece
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Takahashi D, Arimoto H. Selective autophagy as the basis of autophagy-based degraders. Cell Chem Biol 2021; 28:1061-1071. [PMID: 34087173 DOI: 10.1016/j.chembiol.2021.05.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2021] [Revised: 04/23/2021] [Accepted: 05/07/2021] [Indexed: 01/13/2023]
Abstract
Degrader technologies, which enable the chemical knockdown of disease-causing proteins, are promising for drug discovery. After two decades of research, degraders using the ubiquitin-proteasome system (UPS) are currently in clinical trials. However, the UPS substrates are mainly limited to soluble proteins. Autophagy-targeting chimeras and autophagosome-tethering compounds are degraders that use autophagy, which has functions complementary to the UPS. They can degrade organelles and aggregate-prone proteins, making them promising treatments against age-related conditions such as mitochondrial dysfunction and neurodegenerative diseases. The molecular mechanism of selective autophagy is an ongoing research topic, which explains why autophagy-based degraders were not available until recently. In this review, we introduce four classifications of selective autophagy mechanisms to facilitate the understanding of the degrader design.
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Affiliation(s)
- Daiki Takahashi
- Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan
| | - Hirokazu Arimoto
- Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan.
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10
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Harmon KK, Stout JR, Fukuda DH, Pabian PS, Rawson ES, Stock MS. The Application of Creatine Supplementation in Medical Rehabilitation. Nutrients 2021; 13:1825. [PMID: 34071875 PMCID: PMC8230227 DOI: 10.3390/nu13061825] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Revised: 05/17/2021] [Accepted: 05/26/2021] [Indexed: 02/07/2023] Open
Abstract
Numerous health conditions affecting the musculoskeletal, cardiopulmonary, and nervous systems can result in physical dysfunction, impaired performance, muscle weakness, and disuse-induced atrophy. Due to its well-documented anabolic potential, creatine monohydrate has been investigated as a supplemental agent to mitigate the loss of muscle mass and function in a variety of acute and chronic conditions. A review of the literature was conducted to assess the current state of knowledge regarding the effects of creatine supplementation on rehabilitation from immobilization and injury, neurodegenerative diseases, cardiopulmonary disease, and other muscular disorders. Several of the findings are encouraging, showcasing creatine's potential efficacy as a supplemental agent via preservation of muscle mass, strength, and physical function; however, the results are not consistent. For multiple diseases, only a few creatine studies with small sample sizes have been published, making it difficult to draw definitive conclusions. Rationale for discordant findings is further complicated by differences in disease pathologies, intervention protocols, creatine dosing and duration, and patient population. While creatine supplementation demonstrates promise as a therapeutic aid, more research is needed to fill gaps in knowledge within medical rehabilitation.
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Affiliation(s)
- Kylie K. Harmon
- Neuromuscular Plasticity Laboratory, Institute of Exercise Physiology and Rehabilitation Science, School of Kinesiology and Physical Therapy, University of Central Florida, Orlando, FL 32816, USA;
| | - Jeffrey R. Stout
- Physiology of Work and Exercise Response (POWER) Laboratory, Institute of Exercise Physiology and Rehabilitation Science, School of Kinesiology and Physical Therapy, University of Central Florida, Orlando, FL 32816, USA; (J.R.S.); (D.H.F.)
| | - David H. Fukuda
- Physiology of Work and Exercise Response (POWER) Laboratory, Institute of Exercise Physiology and Rehabilitation Science, School of Kinesiology and Physical Therapy, University of Central Florida, Orlando, FL 32816, USA; (J.R.S.); (D.H.F.)
| | - Patrick S. Pabian
- Musculoskeletal Research Laboratory, Institute of Exercise Physiology and Rehabilitation Science, School of Kinesiology and Physical Therapy, University of Central Florida, Orlando, FL 32816, USA;
| | - Eric S. Rawson
- Department of Health, Nutrition, and Exercise Science, Messiah University, Mechanicsburg, PA 17055, USA;
| | - Matt S. Stock
- Neuromuscular Plasticity Laboratory, Institute of Exercise Physiology and Rehabilitation Science, School of Kinesiology and Physical Therapy, University of Central Florida, Orlando, FL 32816, USA;
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11
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Nesci S, Trombetti F, Pagliarani A, Ventrella V, Algieri C, Tioli G, Lenaz G. Molecular and Supramolecular Structure of the Mitochondrial Oxidative Phosphorylation System: Implications for Pathology. Life (Basel) 2021; 11:242. [PMID: 33804034 PMCID: PMC7999509 DOI: 10.3390/life11030242] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Revised: 03/09/2021] [Accepted: 03/11/2021] [Indexed: 02/07/2023] Open
Abstract
Under aerobic conditions, mitochondrial oxidative phosphorylation (OXPHOS) converts the energy released by nutrient oxidation into ATP, the currency of living organisms. The whole biochemical machinery is hosted by the inner mitochondrial membrane (mtIM) where the protonmotive force built by respiratory complexes, dynamically assembled as super-complexes, allows the F1FO-ATP synthase to make ATP from ADP + Pi. Recently mitochondria emerged not only as cell powerhouses, but also as signaling hubs by way of reactive oxygen species (ROS) production. However, when ROS removal systems and/or OXPHOS constituents are defective, the physiological ROS generation can cause ROS imbalance and oxidative stress, which in turn damages cell components. Moreover, the morphology of mitochondria rules cell fate and the formation of the mitochondrial permeability transition pore in the mtIM, which, most likely with the F1FO-ATP synthase contribution, permeabilizes mitochondria and leads to cell death. As the multiple mitochondrial functions are mutually interconnected, changes in protein composition by mutations or in supercomplex assembly and/or in membrane structures often generate a dysfunctional cascade and lead to life-incompatible diseases or severe syndromes. The known structural/functional changes in mitochondrial proteins and structures, which impact mitochondrial bioenergetics because of an impaired or defective energy transduction system, here reviewed, constitute the main biochemical damage in a variety of genetic and age-related diseases.
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Affiliation(s)
- Salvatore Nesci
- Department of Veterinary Medical Sciences, Alma Mater Studiorum University of Bologna, 40064 Ozzano Emilia, Italy; (F.T.); (V.V.); (C.A.)
| | - Fabiana Trombetti
- Department of Veterinary Medical Sciences, Alma Mater Studiorum University of Bologna, 40064 Ozzano Emilia, Italy; (F.T.); (V.V.); (C.A.)
| | - Alessandra Pagliarani
- Department of Veterinary Medical Sciences, Alma Mater Studiorum University of Bologna, 40064 Ozzano Emilia, Italy; (F.T.); (V.V.); (C.A.)
| | - Vittoria Ventrella
- Department of Veterinary Medical Sciences, Alma Mater Studiorum University of Bologna, 40064 Ozzano Emilia, Italy; (F.T.); (V.V.); (C.A.)
| | - Cristina Algieri
- Department of Veterinary Medical Sciences, Alma Mater Studiorum University of Bologna, 40064 Ozzano Emilia, Italy; (F.T.); (V.V.); (C.A.)
| | - Gaia Tioli
- Department of Biomedical and Neuromotor Sciences, Alma Mater Studiorum University of Bologna, 40138 Bologna, Italy;
| | - Giorgio Lenaz
- Department of Biomedical and Neuromotor Sciences, Alma Mater Studiorum University of Bologna, 40138 Bologna, Italy;
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12
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Kargaran PK, Mosqueira D, Kozicz T. Mitochondrial Medicine: Genetic Underpinnings and Disease Modeling Using Induced Pluripotent Stem Cell Technology. Front Cardiovasc Med 2021; 7:604581. [PMID: 33585579 PMCID: PMC7874022 DOI: 10.3389/fcvm.2020.604581] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Accepted: 12/22/2020] [Indexed: 12/14/2022] Open
Abstract
Mitochondrial medicine is an exciting and rapidly evolving field. While the mitochondrial genome is small and differs from the nuclear genome in that it is circular and free of histones, it has been implicated in neurodegenerative diseases, type 2 diabetes, aging and cardiovascular disorders. Currently, there is a lack of efficient treatments for mitochondrial diseases. This has promoted the need for developing an appropriate platform to investigate and target the mitochondrial genome. However, developing these therapeutics requires a model system that enables rapid and effective studying of potential candidate therapeutics. In the past decade, induced pluripotent stem cells (iPSCs) have become a promising technology for applications in basic science and clinical trials, and have the potential to be transformative for mitochondrial drug development. Engineered iPSC-derived cardiomyocytes (iPSC-CM) offer a unique tool to model mitochondrial disorders. Additionally, these cellular models enable the discovery and testing of novel therapeutics and their impact on pathogenic mtDNA variants and dysfunctional mitochondria. Herein, we review recent advances in iPSC-CM models focused on mitochondrial dysfunction often causing cardiovascular diseases. The importance of mitochondrial disease systems biology coupled with genetically encoded NAD+/NADH sensors is addressed toward developing an in vitro translational approach to establish effective therapies.
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Affiliation(s)
- Parisa K Kargaran
- Department of Cardiovascular Medicine, Center for Regenerative Medicine, Mayo Clinic, Rochester, MN, United States
| | - Diogo Mosqueira
- Division of Cancer & Stem Cells, Biodiscovery Institute, University of Nottingham, Nottingham, United Kingdom
| | - Tamas Kozicz
- Department of Clinical Genomics, Mayo Clinic, Rochester, MN, United States
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13
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Systemic Delivery of AAV-Fdxr Mitigates the Phenotypes of Mitochondrial Disorders in Fdxr Mutant Mice. Mol Ther Methods Clin Dev 2020; 18:84-97. [PMID: 32995353 PMCID: PMC7488755 DOI: 10.1016/j.omtm.2020.05.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Accepted: 05/19/2020] [Indexed: 11/23/2022]
Abstract
Gene therapy now provides a novel approach for treating inherited monogenetic disorders, including nuclear gene mutations associated with mitochondrial diseases. In this study, we have utilized a mouse model carrying a p.Arg389Gln mutation of the mitochondrial Ferredoxin Reductase gene (Fdxr) and treated them with neurotropic AAV-PHP.B vector loaded with the mouse Fdxr cDNA sequence. We then used immunofluorescence staining and western blot to test the transduction efficiency of this vector. Toluidine blue staining and electronic microscopy were also utilized to assess the morphology of optic and sciatic nerves, and the mitochondrial respiratory chain activity was determined as well. The AAV vector effectively transduced in the central nervous system and peripheral organs, and AAV-Fdxr treatment reversed almost all the symptoms of the mutants (FdxrR389Q/R389Q). This therapy also improved the electronic conductivity of the sciatic nerves, prevented optic atrophy, improved mobility, and restored mitochondrial complex function. Most notably, the sensory neuropathy, neurodegeneration, and chronic neuroinflammation in the brain were alleviated. Overall, we present the first demonstration of a potential definitive treatment that significantly improves optic and sciatic nerve atrophy, sensory neuropathy, and mitochondrial dysfunction in FDXR-related mitochondriopathy. Our study provides substantial support for the translation of AAV-based Fdxr gene therapy into clinical applications.
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14
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Stable retention of chloramphenicol-resistant mtDNA to rescue metabolically impaired cells. Sci Rep 2020; 10:14328. [PMID: 32868785 PMCID: PMC7459123 DOI: 10.1038/s41598-020-71199-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Accepted: 08/10/2020] [Indexed: 12/27/2022] Open
Abstract
The permanent transfer of specific mtDNA sequences into mammalian cells could generate improved models of mtDNA disease and support future cell-based therapies. Previous studies documented multiple biochemical changes in recipient cells shortly after mtDNA transfer, but the long-term retention and function of transferred mtDNA remains unknown. Here, we evaluate mtDNA retention in new host cells using ‘MitoPunch’, a device that transfers isolated mitochondria into mouse and human cells. We show that newly introduced mtDNA is stably retained in mtDNA-deficient (ρ0) recipient cells following uridine-free selection, although exogenous mtDNA is lost from metabolically impaired, mtDNA-intact (ρ+) cells. We then introduced a second selective pressure by transferring chloramphenicol-resistant mitochondria into chloramphenicol-sensitive, metabolically impaired ρ+ mouse cybrid cells. Following double selection, recipient cells with mismatched nuclear (nDNA) and mitochondrial (mtDNA) genomes retained transferred mtDNA, which replaced the endogenous mutant mtDNA and improved cell respiration. However, recipient cells with matched mtDNA-nDNA failed to retain transferred mtDNA and sustained impaired respiration. Our results suggest that exogenous mtDNA retention in metabolically impaired ρ+ recipients depends on the degree of recipient mtDNA-nDNA co-evolution. Uncovering factors that stabilize exogenous mtDNA integration will improve our understanding of in vivo mitochondrial transfer and the interplay between mitochondrial and nuclear genomes.
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15
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Bioenergetic consequences from xenotopic expression of a tunicate AOX in mouse mitochondria: Switch from RET and ROS to FET. BIOCHIMICA ET BIOPHYSICA ACTA. BIOENERGETICS 2020; 1861:148137. [PMID: 31825809 DOI: 10.1016/j.bbabio.2019.148137] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Revised: 12/01/2019] [Accepted: 12/05/2019] [Indexed: 12/23/2022]
Abstract
Electron transfer from all respiratory chain dehydrogenases of the electron transport chain (ETC) converges at the level of the quinone (Q) pool. The Q redox state is thus a function of electron input (reduction) and output (oxidation) and closely reflects the mitochondrial respiratory state. Disruption of electron flux at the level of the cytochrome bc1 complex (cIII) or cytochrome c oxidase (cIV) shifts the Q redox poise to a more reduced state which is generally sensed as respiratory stress. To cope with respiratory stress, many species, but not insects and vertebrates, express alternative oxidase (AOX) which acts as an electron sink for reduced Q and by-passes cIII and cIV. Here, we used Ciona intestinalis AOX xenotopically expressed in mouse mitochondria to study how respiratory states impact the Q poise and how AOX may be used to restore respiration. Particularly interesting is our finding that electron input through succinate dehydrogenase (cII), but not NADH:ubiquinone oxidoreductase (cI), reduces the Q pool almost entirely (>90%) irrespective of the respiratory state. AOX enhances the forward electron transport (FET) from cII thereby decreasing reverse electron transport (RET) and ROS specifically when non-phosphorylating. AOX is not engaged with cI substrates, however, unless a respiratory inhibitor is added. This sheds new light on Q poise signaling, the biological role of cII which enigmatically is the only ETC complex absent from respiratory supercomplexes but yet participates in the tricarboxylic acid (TCA) cycle. Finally, we delineate potential risks and benefits arising from therapeutic AOX transfer.
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16
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Coenzyme Q10-Polyethylene Glycol Monostearate Nanoparticles: An Injectable Water-Soluble Formulation. Antioxidants (Basel) 2020; 9:antiox9010086. [PMID: 31963934 PMCID: PMC7023414 DOI: 10.3390/antiox9010086] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Revised: 01/14/2020] [Accepted: 01/17/2020] [Indexed: 12/02/2022] Open
Abstract
Therapeutic applications of coenzyme Q10 (CoQ10) are greatly limited by its lack of solubility in aqueous media. In this study, polyethylene glycol monostearate (stPEG) was used to construct micelles containing CoQ10 as a new formulation. The micellar formulations (stPEG/CoQ10) were prepared using five types of stPEG with 10, 25, 40, 55, and 140 PEG repeat units, respectively. The micellar preparation was simple, consisting of only stPEG and CoQ10. Next, we compared the physical properties and blood circulation of these micelles. The CoQ10 load of this formulation was approximately 15 w/w%. Based on the dynamic light scattering method, the average molecular size of the stPEG/CoQ10 micelles was approximately 15 to 60 nm. The zeta potentials of these micelles were approximately −10 to −25 mV. The micelles using stPEG25, 40, and 55 demonstrated high solubility in water. Furthermore, these micelles had in vitro antioxidant activity. On comparing the blood circulation of micelles using stPEG25, 40, 55, and 140, micelles using stPEG55 had a significantly higher circulation in blood. The stPEG55/CoQ10 micelle demonstrated a protective effect against acetaminophen-induced liver injury in mice. In conclusion, these data indicate that the intravenous administration of the stPEG/CoQ10 micellar aqueous formulation is of great value against oxidant stress.
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17
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Almannai M, Alfadhel M, El-Hattab AW. Carnitine Inborn Errors of Metabolism. Molecules 2019; 24:molecules24183251. [PMID: 31500110 PMCID: PMC6766900 DOI: 10.3390/molecules24183251] [Citation(s) in RCA: 65] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Revised: 08/29/2019] [Accepted: 09/04/2019] [Indexed: 12/21/2022] Open
Abstract
Carnitine plays essential roles in intermediary metabolism. In non-vegetarians, most of carnitine sources (~75%) are obtained from diet whereas endogenous synthesis accounts for around 25%. Renal carnitine reabsorption along with dietary intake and endogenous production maintain carnitine homeostasis. The precursors for carnitine biosynthesis are lysine and methionine. The biosynthetic pathway involves four enzymes: 6-N-trimethyllysine dioxygenase (TMLD), 3-hydroxy-6-N-trimethyllysine aldolase (HTMLA), 4-N-trimethylaminobutyraldehyde dehydrogenase (TMABADH), and γ-butyrobetaine dioxygenase (BBD). OCTN2 (organic cation/carnitine transporter novel type 2) transports carnitine into the cells. One of the major functions of carnitine is shuttling long-chain fatty acids across the mitochondrial membrane from the cytosol into the mitochondrial matrix for β-oxidation. This transport is achieved by mitochondrial carnitine–acylcarnitine cycle, which consists of three enzymes: carnitine palmitoyltransferase I (CPT I), carnitine-acylcarnitine translocase (CACT), and carnitine palmitoyltransferase II (CPT II). Carnitine inborn errors of metabolism could result from defects in carnitine biosynthesis, carnitine transport, or mitochondrial carnitine–acylcarnitine cycle. The presentation of these disorders is variable but common findings include hypoketotic hypoglycemia, cardio(myopathy), and liver disease. In this review, the metabolism and homeostasis of carnitine are discussed. Then we present details of different inborn errors of carnitine metabolism, including clinical presentation, diagnosis, and treatment options. At the end, we discuss some of the causes of secondary carnitine deficiency.
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Affiliation(s)
- Mohammed Almannai
- Section of Medical Genetics, Children's Hospital, King Fahad Medical City, Riyadh 11525, Saudi Arabia.
| | - Majid Alfadhel
- Division of Genetics, Department of Pediatrics, King Abdulaziz Medical City, Ministry of National Guard-Health Affairs (MNGHA), Riyadh 11426, Saudi Arabia.
- King Abdullah International Medical Research Center (KAIMRC), Riyadh 11426, Saudi Arabia.
- College of Medicine, King Saud Bin Abdulaziz University for Health Sciences, Riyadh 11426, Saudi Arabia.
| | - Ayman W El-Hattab
- Department of Clinical Sciences, College of Medicine, University of Sharjah, Sharjah 27272, UAE.
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18
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Rubalcava-Gracia D, García-Rincón J, Pérez-Montfort R, Hamel PP, González-Halphen D. Key within-membrane residues and precursor dosage impact the allotopic expression of yeast subunit II of cytochrome c oxidase. Mol Biol Cell 2019; 30:2358-2366. [PMID: 31318312 PMCID: PMC6741066 DOI: 10.1091/mbc.e18-12-0788] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Experimentally relocating mitochondrial genes to the nucleus for functional expression (allotopic expression) is a challenging process. The high hydrophobicity of mitochondria-encoded proteins seems to be one of the main factors preventing this allotopic expression. We focused on subunit II of cytochrome c oxidase (Cox2) to study which modifications may enable or improve its allotopic expression in yeast. Cox2 can be imported from the cytosol into mitochondria in the presence of the W56R substitution, which decreases the protein hydrophobicity and allows partial respiratory rescue of a cox2-null strain. We show that the inclusion of a positive charge is more favorable than substitutions that only decrease the hydrophobicity. We also searched for other determinants enabling allotopic expression in yeast by examining the COX2 gene in organisms where it was transferred to the nucleus during evolution. We found that naturally occurring variations at within-membrane residues in the legume Glycine max Cox2 could enable yeast COX2 allotopic expression. We also evidence that directing high doses of allotopically synthesized Cox2 to mitochondria seems to be counterproductive because the subunit aggregates at the mitochondrial surface. Our findings are relevant to the design of allotopic expression strategies and contribute to the understanding of gene retention in organellar genomes.
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Affiliation(s)
- Diana Rubalcava-Gracia
- Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Ciudad de México 04510, Mexico
| | - Juan García-Rincón
- Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Ciudad de México 04510, Mexico
| | - Ruy Pérez-Montfort
- Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Ciudad de México 04510, Mexico
| | - Patrice Paul Hamel
- Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210
| | - Diego González-Halphen
- Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Ciudad de México 04510, Mexico
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19
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Set KK, Sen K, Huq AHM, Agarwal R. Mitochondrial Disorders of the Nervous System: A Review. Clin Pediatr (Phila) 2019; 58:381-394. [PMID: 30607979 DOI: 10.1177/0009922818821890] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Kallol K Set
- 1 Dayton Children's Hospital, Dayton, OH, USA.,2 Wright State University Boonshoft School of Medicine, Dayton, OH, USA
| | - Kuntal Sen
- 3 Children's Hospital of Michigan, Detroit, MI, USA.,4 Wayne State University School of Medicine, Detroit, MI, USA
| | - A H M Huq
- 3 Children's Hospital of Michigan, Detroit, MI, USA.,4 Wayne State University School of Medicine, Detroit, MI, USA
| | - Rajkumar Agarwal
- 1 Dayton Children's Hospital, Dayton, OH, USA.,2 Wright State University Boonshoft School of Medicine, Dayton, OH, USA
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20
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Siempos II, Ma KC, Imamura M, Baron RM, Fredenburgh LE, Huh JW, Moon JS, Finkelsztein EJ, Jones DS, Lizardi MT, Schenck EJ, Ryter SW, Nakahira K, Choi AM. RIPK3 mediates pathogenesis of experimental ventilator-induced lung injury. JCI Insight 2018; 3:97102. [PMID: 29720570 DOI: 10.1172/jci.insight.97102] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Accepted: 04/04/2018] [Indexed: 12/18/2022] Open
Abstract
In patients requiring ventilator support, mechanical ventilation (MV) may induce acute lung injury (ventilator-induced lung injury [VILI]). VILI is associated with substantial morbidity and mortality in mechanically ventilated patients with and without acute respiratory distress syndrome. At the cellular level, VILI induces necrotic cell death. However, the contribution of necroptosis, a programmed form of necrotic cell death regulated by receptor-interacting protein-3 kinase (RIPK3) and mixed-lineage kinase domain-like pseudokinase (MLKL), to the development of VILI remains unexplored. Here, we show that plasma levels of RIPK3, but not MLKL, were higher in patients with MV (i.e., those prone to VILI) than in patients without MV (i.e., those less likely to have VILI) in two large intensive care unit cohorts. In mice, RIPK3 deficiency, but not MLKL deficiency, ameliorated VILI. In both humans and mice, VILI was associated with impaired fatty acid oxidation (FAO), but in mice this association was not observed under conditions of RIPK3 deficiency. These findings suggest that FAO-dependent RIPK3 mediates pathogenesis of acute lung injury.
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Affiliation(s)
- Ilias I Siempos
- Department of Medicine, Division of Pulmonary and Critical Care Medicine, New York-Presbyterian Hospital/Weill Cornell Medical Center, Weill Cornell Medicine (WCM), New York, New York, USA.,First Department of Critical Care Medicine and Pulmonary Services, Evangelismos Hospital, University of Athens Medical School, Athens, Greece
| | - Kevin C Ma
- Department of Medicine, Division of Pulmonary and Critical Care Medicine, New York-Presbyterian Hospital/Weill Cornell Medical Center, Weill Cornell Medicine (WCM), New York, New York, USA
| | - Mitsuru Imamura
- Department of Medicine, Division of Pulmonary and Critical Care Medicine, New York-Presbyterian Hospital/Weill Cornell Medical Center, Weill Cornell Medicine (WCM), New York, New York, USA
| | - Rebecca M Baron
- Division of Pulmonary and Critical Medicine, Brigham and Women's Hospital (BWH), Harvard Medical School, Boston, Massachusetts, USA
| | - Laura E Fredenburgh
- Division of Pulmonary and Critical Medicine, Brigham and Women's Hospital (BWH), Harvard Medical School, Boston, Massachusetts, USA
| | - Jin-Won Huh
- Department of Pulmonary and Critical Care Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
| | - Jong-Seok Moon
- Department of Medicine, Division of Pulmonary and Critical Care Medicine, New York-Presbyterian Hospital/Weill Cornell Medical Center, Weill Cornell Medicine (WCM), New York, New York, USA
| | - Eli J Finkelsztein
- Department of Medicine, Division of Pulmonary and Critical Care Medicine, New York-Presbyterian Hospital/Weill Cornell Medical Center, Weill Cornell Medicine (WCM), New York, New York, USA
| | - Daniel S Jones
- Department of Medicine, Division of Pulmonary and Critical Care Medicine, New York-Presbyterian Hospital/Weill Cornell Medical Center, Weill Cornell Medicine (WCM), New York, New York, USA
| | - Michael Torres Lizardi
- Department of Medicine, New York-Presbyterian Hospital/Weill Cornell Medical Center, WCM, New York, New York, USA
| | - Edward J Schenck
- Department of Medicine, Division of Pulmonary and Critical Care Medicine, New York-Presbyterian Hospital/Weill Cornell Medical Center, Weill Cornell Medicine (WCM), New York, New York, USA
| | - Stefan W Ryter
- Department of Medicine, Division of Pulmonary and Critical Care Medicine, New York-Presbyterian Hospital/Weill Cornell Medical Center, Weill Cornell Medicine (WCM), New York, New York, USA
| | - Kiichi Nakahira
- Department of Medicine, Division of Pulmonary and Critical Care Medicine, New York-Presbyterian Hospital/Weill Cornell Medical Center, Weill Cornell Medicine (WCM), New York, New York, USA
| | - Augustine Mk Choi
- Department of Medicine, New York-Presbyterian Hospital/Weill Cornell Medical Center, WCM, New York, New York, USA
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21
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Karaa A, Haas R, Goldstein A, Vockley J, Weaver WD, Cohen BH. Randomized dose-escalation trial of elamipretide in adults with primary mitochondrial myopathy. Neurology 2018; 90:e1212-e1221. [PMID: 29500292 PMCID: PMC5890606 DOI: 10.1212/wnl.0000000000005255] [Citation(s) in RCA: 90] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Accepted: 12/12/2017] [Indexed: 01/03/2023] Open
Abstract
OBJECTIVE To assess the safety and efficacy of elamipretide, an aromatic-cationic tetrapeptide that readily penetrates cell membranes and transiently localizes to the inner mitochondrial membrane where it associates with cardiolipin, in adults with primary mitochondrial myopathy (PMM). METHODS A Study Investigating the Safety, Tolerability, and Efficacy of MTP-131 for the Treatment of Mitochondrial Myopathy (MMPOWER) was a phase I/II multicenter, randomized, double-blind, placebo-controlled trial of elamipretide in 36 participants with genetically confirmed PMM. Participants were randomized to intravenous elamipretide (0.01, 0.1, and 0.25 mg/kg/h or placebo for 2 hours in a dose-escalating sequence). The primary efficacy measure was the change in distance walked in the 6-minute walk test (6MWT) after 5 days of treatment. Other efficacy measures included changes in cardiopulmonary exercise testing parameters, in participant-reported symptoms, and in serum and urinary biomarkers. Safety, tolerability, and pharmacokinetics were also measured. RESULTS Participants who received the highest dose of elamipretide walked a mean of 64.5 m farther at day 5 compared to a change of 20.4 m in the placebo group (p = 0.053). In addition, there was a dose-dependent increase in distance walked on the 6MWT with elamipretide treatment (p = 0.014). In a model that adjusted for additional covariates possibly affecting response, the adjusted change for the highest dose of elamipretide was 51.2 vs 3.0 m in the placebo group (p = 0.0297). No significant differences were observed in other efficacy and safety endpoints. CONCLUSIONS Elamipretide increased exercise performance after 5 days of treatment in patients with PMM without increased safety concerns. These findings, as well as additional functional and patient-reported measures, remain to be tested in larger trials with longer treatment periods to detect other potential therapeutic benefits in individuals affected by this condition. CLASSIFICATION OF EVIDENCE This trial provides Class I evidence that for patients with PMM, elamipretide improved the distance walked on the 6MWT.
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Affiliation(s)
- Amel Karaa
- From the Genetics Unit (A.K.), Massachusetts General Hospital, Boston; UC San Diego School of Medicine (R.H.), La Jolla, CA; Children's Hospital of Pittsburgh (A.G., J.V.), PA; Stealth BioTherapeutics (W.D.W.), Newton, MA; and Akron Children's Hospital (B.H.C.), OH.
| | - Richard Haas
- From the Genetics Unit (A.K.), Massachusetts General Hospital, Boston; UC San Diego School of Medicine (R.H.), La Jolla, CA; Children's Hospital of Pittsburgh (A.G., J.V.), PA; Stealth BioTherapeutics (W.D.W.), Newton, MA; and Akron Children's Hospital (B.H.C.), OH
| | - Amy Goldstein
- From the Genetics Unit (A.K.), Massachusetts General Hospital, Boston; UC San Diego School of Medicine (R.H.), La Jolla, CA; Children's Hospital of Pittsburgh (A.G., J.V.), PA; Stealth BioTherapeutics (W.D.W.), Newton, MA; and Akron Children's Hospital (B.H.C.), OH
| | - Jerry Vockley
- From the Genetics Unit (A.K.), Massachusetts General Hospital, Boston; UC San Diego School of Medicine (R.H.), La Jolla, CA; Children's Hospital of Pittsburgh (A.G., J.V.), PA; Stealth BioTherapeutics (W.D.W.), Newton, MA; and Akron Children's Hospital (B.H.C.), OH
| | - W Douglas Weaver
- From the Genetics Unit (A.K.), Massachusetts General Hospital, Boston; UC San Diego School of Medicine (R.H.), La Jolla, CA; Children's Hospital of Pittsburgh (A.G., J.V.), PA; Stealth BioTherapeutics (W.D.W.), Newton, MA; and Akron Children's Hospital (B.H.C.), OH
| | - Bruce H Cohen
- From the Genetics Unit (A.K.), Massachusetts General Hospital, Boston; UC San Diego School of Medicine (R.H.), La Jolla, CA; Children's Hospital of Pittsburgh (A.G., J.V.), PA; Stealth BioTherapeutics (W.D.W.), Newton, MA; and Akron Children's Hospital (B.H.C.), OH
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22
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Rubalcava-Gracia D, Vázquez-Acevedo M, Funes S, Pérez-Martínez X, González-Halphen D. Mitochondrial versus nuclear gene expression and membrane protein assembly: the case of subunit 2 of yeast cytochrome c oxidase. Mol Biol Cell 2018; 29:820-833. [PMID: 29437907 PMCID: PMC5905295 DOI: 10.1091/mbc.e17-09-0560] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Revised: 01/12/2018] [Accepted: 02/01/2018] [Indexed: 12/24/2022] Open
Abstract
Deletion of the yeast mitochondrial gene COX2, encoding subunit 2 (mtCox2) of cytochrome c oxidase (CcO), results in a respiratory-incompetent Δcox2 strain. For a cytosol-synthesized Cox2 to restore respiratory growth, it must carry the W56R mutation (cCox2W56R). Nevertheless, only a fraction of cCox2W56R is matured in mitochondria, allowing ∼60% steady-state accumulation of CcO. This can be attributed either to the point mutation or to an inefficient biogenesis of cCox2W56R. We generated a strain expressing the mutant protein mtCox2W56R inside mitochondria which should follow the canonical biogenesis of mitochondria-encoded Cox2. This strain exhibited growth rates, CcO steady-state levels, and CcO activity similar to those of the wild type; therefore, the efficiency of Cox2 biogenesis is the limiting step for successful allotopic expression. Upon coexpression of cCox2W56R and mtCox2, each protein assembled into CcO independently from its genetic origin, resulting in a mixed population of CcO with most complexes containing the mtCox2 version. Notably, the presence of the mtCox2 enhances cCox2W56R incorporation. We provide proof of principle that an allotopically expressed Cox2 may complement a phenotype due to a mutant mitochondrial COX2 gene. These results are relevant to developing a rational design of genes for allotopic expression intended to treat human mitochondrial diseases.
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Affiliation(s)
- Diana Rubalcava-Gracia
- Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, 04510 Ciudad México, D. F., Mexico
| | - Miriam Vázquez-Acevedo
- Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, 04510 Ciudad México, D. F., Mexico
| | - Soledad Funes
- Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, 04510 Ciudad México, D. F., Mexico
| | - Xochitl Pérez-Martínez
- Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, 04510 Ciudad México, D. F., Mexico
| | - Diego González-Halphen
- Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, 04510 Ciudad México, D. F., Mexico
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23
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Mitochondrial transgene expression via an artificial mitochondrial DNA vector in cells from a patient with a mitochondrial disease. J Control Release 2018; 274:109-117. [DOI: 10.1016/j.jconrel.2018.02.005] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Revised: 01/11/2018] [Accepted: 02/02/2018] [Indexed: 11/20/2022]
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24
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Kuszak AJ, Espey MG, Falk MJ, Holmbeck MA, Manfredi G, Shadel GS, Vernon HJ, Zolkipli-Cunningham Z. Nutritional Interventions for Mitochondrial OXPHOS Deficiencies: Mechanisms and Model Systems. ANNUAL REVIEW OF PATHOLOGY 2018; 13:163-191. [PMID: 29099651 PMCID: PMC5911915 DOI: 10.1146/annurev-pathol-020117-043644] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Multisystem metabolic disorders caused by defects in oxidative phosphorylation (OXPHOS) are severe, often lethal, conditions. Inborn errors of OXPHOS function are termed primary mitochondrial disorders (PMDs), and the use of nutritional interventions is routine in their supportive management. However, detailed mechanistic understanding and evidence for efficacy and safety of these interventions are limited. Preclinical cellular and animal model systems are important tools to investigate PMD metabolic mechanisms and therapeutic strategies. This review assesses the mechanistic rationale and experimental evidence for nutritional interventions commonly used in PMDs, including micronutrients, metabolic agents, signaling modifiers, and dietary regulation, while highlighting important knowledge gaps and impediments for randomized controlled trials. Cellular and animal model systems that recapitulate mutations and clinical manifestations of specific PMDs are evaluated for their potential in determining pathological mechanisms, elucidating therapeutic health outcomes, and investigating the value of nutritional interventions for mitochondrial disease conditions.
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Affiliation(s)
- Adam J Kuszak
- Office of Dietary Supplements, National Institutes of Health, Bethesda, Maryland 20852, USA;
| | - Michael Graham Espey
- Division of Cancer Biology, National Cancer Institute, Rockville, Maryland 20850, USA;
| | - Marni J Falk
- Department of Pediatrics, Division of Human Genetics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania 19104, USA;
- Department of Pediatrics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Marissa A Holmbeck
- Department of Pathology, Yale School of Medicine, New Haven, Connecticut 06510-8023, USA;
| | - Giovanni Manfredi
- Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY 10065, USA;
| | - Gerald S Shadel
- Department of Pathology, Yale School of Medicine, New Haven, Connecticut 06510-8023, USA;
- Department of Genetics, Yale School of Medicine, New Haven, Connecticut 06520-8023, USA;
| | - Hilary J Vernon
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University, Baltimore, Maryland 21205, USA;
| | - Zarazuela Zolkipli-Cunningham
- Department of Pediatrics, Division of Neurology, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania 19104, USA;
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25
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Jackson CB, Hahn D, Schröter B, Richter U, Battersby BJ, Schmitt-Mechelke T, Marttinen P, Nuoffer JM, Schaller A. A novel mitochondrial ATP6 frameshift mutation causing isolated complex V deficiency, ataxia and encephalomyopathy. Eur J Med Genet 2017; 60:345-351. [PMID: 28412374 DOI: 10.1016/j.ejmg.2017.04.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Revised: 04/03/2017] [Accepted: 04/10/2017] [Indexed: 12/15/2022]
Abstract
We describe a novel frameshift mutation in the mitochondrial ATP6 gene in a 4-year-old girl associated with ataxia, microcephaly, developmental delay and intellectual disability. A heteroplasmic frameshift mutation in the MT-ATP6 gene was confirmed in the patient's skeletal muscle and blood. The mutation was not detectable in the mother's DNA extracted from blood or buccal cells. Enzymatic and oxymetric analysis of the mitochondrial respiratory system in the patients' skeletal muscle and skin fibroblasts demonstrated an isolated complex V deficiency. Native PAGE with subsequent immunoblotting for complex V revealed impaired complex V assembly and accumulation of ATPase subcomplexes. Whilst northern blotting confirmed equal presence of ATP8/6 mRNA, metabolic 35S-labelling of mitochondrial translation products showed a severe depletion of the ATP6 protein together with aberrant translation product accumulation. In conclusion, this novel isolated complex V defect expands the clinical and genetic spectrum of mitochondrial defects of complex V deficiency. Furthermore, this work confirms the benefit of native PAGE as an additional diagnostic method for the identification of OXPHOS defects, as the presence of complex V subcomplexes is associated with pathogenic mutations of mtDNA.
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Affiliation(s)
- Christopher B Jackson
- Institute of Clinical Chemistry, University Hospital Bern, Switzerland; Research Programs for Molecular Neurology, Biomedicum Helsinki, University of Helsinki, Finland.
| | - Dagmar Hahn
- Institute of Clinical Chemistry, University Hospital Bern, Switzerland
| | - Barbara Schröter
- Department of Neuropaediatrics, Children's Hospital, Cantonal Hospital Lucerne, Switzerland.
| | - Uwe Richter
- Institute of Biotechnology, University of Helsinki, Finland.
| | | | - Thomas Schmitt-Mechelke
- Department of Neuropaediatrics, Children's Hospital, Cantonal Hospital Lucerne, Switzerland.
| | - Paula Marttinen
- Institute of Biotechnology, University of Helsinki, Finland.
| | - Jean-Marc Nuoffer
- Institute of Clinical Chemistry, University Hospital Bern, Switzerland.
| | - André Schaller
- Division of Human Genetics, Bern, University Hospital Bern, Switzerland.
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Le Borgne F, Ravaut G, Bernard A, Demarquoy J. L-carnitine protects C2C12 cells against mitochondrial superoxide overproduction and cell death. World J Biol Chem 2017; 8:86-94. [PMID: 28289521 PMCID: PMC5329717 DOI: 10.4331/wjbc.v8.i1.86] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Revised: 09/29/2016] [Accepted: 12/14/2016] [Indexed: 02/05/2023] Open
Abstract
AIM To identify and characterize the protective effect that L-carnitine exerted against an oxidative stress in C2C12 cells.
METHODS Myoblastic C2C12 cells were treated with menadione, a vitamin K analog that engenders oxidative stress, and the protective effect of L-carnitine (a nutrient involved in fatty acid metabolism and the control of the oxidative process), was assessed by monitoring various parameters related to the oxidative stress, autophagy and cell death.
RESULTS Associated with its physiological function, a muscle cell metabolism is highly dependent on oxygen and may produce reactive oxygen species (ROS), especially under pathological conditions. High levels of ROS are known to induce injuries in cell structure as they interact at many levels in cell function. In C2C12 cells, a treatment with menadione induced a loss of transmembrane mitochondrial potential, an increase in mitochondrial production of ROS; it also induces autophagy and was able to provoke cell death. Pre-treatment of the cells with L-carnitine reduced ROS production, diminished autophagy and protected C2C12 cells against menadione-induced deleterious effects.
CONCLUSION In conclusion, L-carnitine limits the oxidative stress in these cells and prevents cell death.
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27
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Yamada Y, Burger L, Kawamura E, Harashima H. Packaging of the Coenzyme Q 10 into a Liposome for Mitochondrial Delivery and the Intracellular Observation in Patient Derived Mitochondrial Disease Cells. Biol Pharm Bull 2017; 40:2183-2190. [DOI: 10.1248/bpb.b17-00609] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Yuma Yamada
- Laboratory for Molecular Design of Pharmaceutics, Faculty of Pharmaceutical Sciences, Hokkaido University
| | - Laila Burger
- Laboratory for Molecular Design of Pharmaceutics, Faculty of Pharmaceutical Sciences, Hokkaido University
| | - Eriko Kawamura
- Laboratory for Molecular Design of Pharmaceutics, Faculty of Pharmaceutical Sciences, Hokkaido University
| | - Hideyoshi Harashima
- Laboratory for Molecular Design of Pharmaceutics, Faculty of Pharmaceutical Sciences, Hokkaido University
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28
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Lasserre JP, Dautant A, Aiyar RS, Kucharczyk R, Glatigny A, Tribouillard-Tanvier D, Rytka J, Blondel M, Skoczen N, Reynier P, Pitayu L, Rötig A, Delahodde A, Steinmetz LM, Dujardin G, Procaccio V, di Rago JP. Yeast as a system for modeling mitochondrial disease mechanisms and discovering therapies. Dis Model Mech 2016; 8:509-26. [PMID: 26035862 PMCID: PMC4457039 DOI: 10.1242/dmm.020438] [Citation(s) in RCA: 101] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Mitochondrial diseases are severe and largely untreatable. Owing to the many essential processes carried out by mitochondria and the complex cellular systems that support these processes, these diseases are diverse, pleiotropic, and challenging to study. Much of our current understanding of mitochondrial function and dysfunction comes from studies in the baker's yeast Saccharomyces cerevisiae. Because of its good fermenting capacity, S. cerevisiae can survive mutations that inactivate oxidative phosphorylation, has the ability to tolerate the complete loss of mitochondrial DNA (a property referred to as ‘petite-positivity’), and is amenable to mitochondrial and nuclear genome manipulation. These attributes make it an excellent model system for studying and resolving the molecular basis of numerous mitochondrial diseases. Here, we review the invaluable insights this model organism has yielded about diseases caused by mitochondrial dysfunction, which ranges from primary defects in oxidative phosphorylation to metabolic disorders, as well as dysfunctions in maintaining the genome or in the dynamics of mitochondria. Owing to the high level of functional conservation between yeast and human mitochondrial genes, several yeast species have been instrumental in revealing the molecular mechanisms of pathogenic human mitochondrial gene mutations. Importantly, such insights have pointed to potential therapeutic targets, as have genetic and chemical screens using yeast. Summary: In this Review, we discuss the use of budding yeast to understand mitochondrial diseases and help in the search for their treatments.
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Affiliation(s)
- Jean-Paul Lasserre
- University Bordeaux-CNRS, IBGC, UMR 5095, 1 rue Camille Saint-Saëns, Bordeaux F-33000, France
| | - Alain Dautant
- University Bordeaux-CNRS, IBGC, UMR 5095, 1 rue Camille Saint-Saëns, Bordeaux F-33000, France
| | - Raeka S Aiyar
- European Molecular Biology Laboratory (EMBL), Genome Biology Unit, Meyerhofstrasse 1, Heidelberg 69117, Germany
| | - Roza Kucharczyk
- Department of Genetics, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw 02-106, Poland
| | - Annie Glatigny
- Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, CEA, CNRS, Université Paris-Sud, 1 avenue de la terrasse, Gif-sur-Yvette 91198, France
| | - Déborah Tribouillard-Tanvier
- Institut National de la Santé et de la Recherche Médicale UMR1078, Université de Bretagne Occidentale, Faculté de Médecine et des Sciences de la Santé, Etablissement Français du Sang (EFS) Bretagne, CHRU Brest, Hôpital Morvan, Laboratoire de Génétique Moléculaire, Brest F-29200, France
| | - Joanna Rytka
- Department of Genetics, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw 02-106, Poland
| | - Marc Blondel
- Institut National de la Santé et de la Recherche Médicale UMR1078, Université de Bretagne Occidentale, Faculté de Médecine et des Sciences de la Santé, Etablissement Français du Sang (EFS) Bretagne, CHRU Brest, Hôpital Morvan, Laboratoire de Génétique Moléculaire, Brest F-29200, France
| | - Natalia Skoczen
- University Bordeaux-CNRS, IBGC, UMR 5095, 1 rue Camille Saint-Saëns, Bordeaux F-33000, France Department of Genetics, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw 02-106, Poland
| | - Pascal Reynier
- UMR CNRS 6214-INSERM U1083, Angers 49933, Cedex 9, France Département de Biochimie et Génétique, Centre Hospitalier Universitaire d'Angers, Angers 49933, Cedex 9, France
| | - Laras Pitayu
- Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, CEA, CNRS, Université Paris-Sud, rue Gregor Mendel, Orsay 91405, France
| | - Agnès Rötig
- Inserm U1163, Hôpital Necker-Enfants-Malades, Institut Imagine, Université Paris Descartes-Sorbonne Paris Cité, 149 rue de Sèvres, Paris 75015, France
| | - Agnès Delahodde
- Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, CEA, CNRS, Université Paris-Sud, rue Gregor Mendel, Orsay 91405, France
| | - Lars M Steinmetz
- European Molecular Biology Laboratory (EMBL), Genome Biology Unit, Meyerhofstrasse 1, Heidelberg 69117, Germany Stanford Genome Technology Center, Department of Biochemistry, Stanford University, Palo Alto, CA 94304, USA Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305-5301, USA
| | - Geneviève Dujardin
- Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, CEA, CNRS, Université Paris-Sud, 1 avenue de la terrasse, Gif-sur-Yvette 91198, France
| | - Vincent Procaccio
- UMR CNRS 6214-INSERM U1083, Angers 49933, Cedex 9, France Département de Biochimie et Génétique, Centre Hospitalier Universitaire d'Angers, Angers 49933, Cedex 9, France
| | - Jean-Paul di Rago
- University Bordeaux-CNRS, IBGC, UMR 5095, 1 rue Camille Saint-Saëns, Bordeaux F-33000, France
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Aretz I, Hardt C, Wittig I, Meierhofer D. An Impaired Respiratory Electron Chain Triggers Down-regulation of the Energy Metabolism and De-ubiquitination of Solute Carrier Amino Acid Transporters. Mol Cell Proteomics 2016; 15:1526-38. [PMID: 26852163 DOI: 10.1074/mcp.m115.053181] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Indexed: 12/25/2022] Open
Abstract
Hundreds of genes have been associated with respiratory chain disease (RCD), the most common inborn error of metabolism so far. Elimination of the respiratory electron chain by depleting the entire mitochondrial DNA (mtDNA, ρ(0) cells) has therefore one of the most severe impacts on the energy metabolism in eukaryotic cells. In this study, proteomic data sets including the post-translational modifications (PTMs) phosphorylation and ubiquitination were integrated with metabolomic data sets and selected enzyme activities in the osteosarcoma cell line 143B.TK(-) A shotgun based SILAC LC-MS proteomics and a targeted metabolomics approach was applied to elucidate the consequences of the ρ(0) state. Pathway and protein-protein interaction (PPI) network analyses revealed a nonuniform down-regulation of the respiratory electron chain, the tricarboxylic acid (TCA) cycle, and the pyruvate metabolism in ρ(0) cells. Metabolites of the TCA cycle were dysregulated, such as a reduction of citric acid and cis-aconitic acid (six and 2.5-fold), and an increase of lactic acid, oxalacetic acid (both twofold), and succinic acid (fivefold) in ρ(0) cells. Signaling pathways such as GPCR, EGFR, G12/13 alpha, and Rho GTPases were up-regulated in ρ(0) cells, which could be indicative for the mitochondrial retrograde response, a pathway of communication from mitochondria to the nucleus. This was supported by our phosphoproteome data, which revealed two main processes, GTPase-related signal transduction and cytoskeleton organization. Furthermore, a general de-ubiquitination in ρ(0) cells was observed, for example, 80S ribosomal proteins were in average threefold and SLC amino acid transporters fivefold de-ubiquitinated. The latter might cause the observed significant increase of amino acid levels in ρ(0) cells. We conclude that an elimination of the respiratory electron chain, e.g. mtDNA depletion, not only leads to an uneven down-regulation of mitochondrial energy pathways, but also triggers the retrograde response.
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Affiliation(s)
- Ina Aretz
- From the ‡Max Planck Institute for Molecular Genetics, Ihnestraße 63-73, 14195 Berlin, Germany; §Freie Universität Berlin, Fachbereich Biologie, Chemie, Pharmazie, Takustraße 3, 14195 Berlin, Germany
| | - Christopher Hardt
- From the ‡Max Planck Institute for Molecular Genetics, Ihnestraße 63-73, 14195 Berlin, Germany
| | - Ilka Wittig
- ¶Functional Proteomics, Faculty of Medicine, Goethe-University, Theodor Stern Kai 7, Haus 26, D-60590 Frankfurt am Main, Germany
| | - David Meierhofer
- From the ‡Max Planck Institute for Molecular Genetics, Ihnestraße 63-73, 14195 Berlin, Germany;
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30
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Affiliation(s)
- J. David Spence
- Stroke Prevention & Atherosclerosis Research CentreRobarts Research InstituteWestern UniversityLondonOntarioCanada
- Division of Clinical PharmacologyDepartment of MedicineWestern UniversityLondonOntarioCanada
| | - George K. Dresser
- Division of Clinical PharmacologyDepartment of MedicineWestern UniversityLondonOntarioCanada
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Khan NA, Govindaraj P, Meena AK, Thangaraj K. Mitochondrial disorders: challenges in diagnosis & treatment. Indian J Med Res 2016; 141:13-26. [PMID: 25857492 PMCID: PMC4405934 DOI: 10.4103/0971-5916.154489] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Mitochondrial dysfunctions are known to be responsible for a number of heterogenous clinical presentations with multi-systemic involvement. Impaired oxidative phosphorylation leading to a decrease in cellular energy (ATP) production is the most important cause underlying these disorders. Despite significant progress made in the field of mitochondrial medicine during the last two decades, the molecular mechanisms underlying these disorders are not fully understood. Since the identification of first mitochondrial DNA (mtDNA) mutation in 1988, there has been an exponential rise in the identification of mtDNA and nuclear DNA mutations that are responsible for mitochondrial dysfunction and disease. Genetic complexity together with ever widening clinical spectrum associated with mitochondrial dysfunction poses a major challenge in diagnosis and treatment. Effective therapy has remained elusive till date and is mostly efficient in relieving symptoms. In this review, we discuss the important clinical and genetic features of mitochondrials disorders with special emphasis on diagnosis and treatment.
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Affiliation(s)
| | | | | | - Kumarasamy Thangaraj
- CSIR-Centre for Cellular & Molecular Biology, Nizam's Institute of Medical Sciences, Hyderabad, India
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32
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Tischner C, Wenz T. Keep the fire burning: Current avenues in the quest of treating mitochondrial disorders. Mitochondrion 2015; 24:32-49. [DOI: 10.1016/j.mito.2015.06.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Revised: 06/18/2015] [Accepted: 06/24/2015] [Indexed: 12/18/2022]
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Lin BY, Kao MC. Therapeutic applications of the TAT-mediated protein transduction system for complex I deficiency and other mitochondrial diseases. Ann N Y Acad Sci 2015; 1350:17-28. [PMID: 26273800 DOI: 10.1111/nyas.12858] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Among the five enzyme complexes in the oxidative phosphorylation system, NADH-coenzyme Q oxidoreductase (also called complex I) is the largest, most intricate, and least understood. This enzyme complex spans the inner mitochondrial membrane and catalyzes the first step of electron transfer by the oxidation of NADH, and thereby provides two electrons for the reduction of quinone to quinol. Complex I deficiency is associated with many severe mitochondrial diseases, including Leber hereditary optic neuropathy and Leigh syndrome. However, to date, conventional treatments for the majority of genetic mitochondrial diseases are only palliative. Developing a reliable and convenient therapeutic approach is therefore considered to be an urgent need. Targeted proteins fused with the protein transduction domain of human immunodeficiency virus 1 transactivator of transcription (TAT) have been shown to enter cells by crossing plasma membranes while retaining their biological activities. Recent developments show that, in fusion with mitochondrial targeting sequences (MTSs), TAT-MTS-bound cargo can be correctly transported into mitochondria and restore the missing function of the cargo protein in patients' cells. The available evidence suggests that the TAT-mediated protein transduction system holds great promise as a potential therapeutic approach to treat complex I deficiency, as well as other mitochondrial diseases.
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Affiliation(s)
- Bo-Yu Lin
- Institute of Molecular Medicine, National Tsing Hua University, Hsinchu, Taiwan
| | - Mou-Chieh Kao
- Institute of Molecular Medicine, National Tsing Hua University, Hsinchu, Taiwan.,Department of Life Science, National Tsing Hua University, Hsinchu, Taiwan
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34
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Burelle Y, Bemeur C, Rivard ME, Thompson Legault J, Boucher G, Morin C, Coderre L, Des Rosiers C. Mitochondrial vulnerability and increased susceptibility to nutrient-induced cytotoxicity in fibroblasts from leigh syndrome French canadian patients. PLoS One 2015; 10:e0120767. [PMID: 25835550 PMCID: PMC4383560 DOI: 10.1371/journal.pone.0120767] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2014] [Accepted: 02/07/2015] [Indexed: 01/20/2023] Open
Abstract
Mutations in LRPPRC are responsible for the French Canadian variant of Leigh Syndrome (LSFC), a severe disorder characterized biochemically by a tissue-specific deficiency of cytochrome c oxidase (COX) and clinically by the occurrence of severe and deadly acidotic crises. Factors that precipitate these crises remain unclear. To better understand the physiopathology and identify potential treatments, we performed a comprehensive analysis of mitochondrial function in LSFC and control fibroblasts. Furthermore, we have used this cell-based model to screen for conditions that promote premature cell death in LSFC cells and test the protective effect of ten interventions targeting well-defined aspects of mitochondrial function. We show that, despite maintaining normal ATP levels, LSFC fibroblasts present several mitochondrial functional abnormalities under normal baseline conditions, which likely impair their capacity to respond to stress. This includes mitochondrial network fragmentation, impaired oxidative phosphorylation capacity, lower membrane potential, increased sensitivity to Ca2+-induced permeability transition, but no changes in reactive oxygen species production. We also show that LSFC fibroblasts display enhanced susceptibility to cell death when exposed to palmitate, an effect that is potentiated by high lactate, while high glucose or acidosis alone or in combination were neutral. Furthermore, we demonstrate that compounds that are known to promote flux through the electron transport chain independent of phosphorylation (methylene blue, dinitrophenol), or modulate fatty acid (L-carnitine) or Krebs cycle metabolism (propionate) are protective, while antioxidants (idebenone, N-acetyl cysteine, resveratrol) exacerbate palmitate plus lactate-induced cell death. Collectively, beyond highlighting multiple alterations in mitochondrial function and increased susceptibility to nutrient-induced cytotoxicity in LSFC fibroblasts, these results raise questions about the nature of the diets, particularly excess fat intake, as well as on the use of antioxidants in patients with LSFC and, possibly, other COX defects.
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Affiliation(s)
- Yan Burelle
- Faculty of Pharmacy, Université de Montréal, Montréal, Canada
| | - Chantal Bemeur
- Faculty of Pharmacy, Université de Montréal, Montréal, Canada
| | - Marie-Eve Rivard
- Montreal Heart Institute, Montreal, Canada
- Department of Nutrition, Faculty of Medicine, Université de Montréal, Montreal, Canada
| | - Julie Thompson Legault
- Montreal Heart Institute, Montreal, Canada
- Department of Nutrition, Faculty of Medicine, Université de Montréal, Montreal, Canada
| | | | | | - Charles Morin
- Department of Pediatrics and Clinical Research Unit, Complexe hospitalier de la Sagamie, Chicoutimi, QC, Canada
| | - Lise Coderre
- Montreal Heart Institute, Montreal, Canada
- Department of Nutrition, Faculty of Medicine, Université de Montréal, Montreal, Canada
- Department of Medicine, Faculty of Medicine, Université de Montréal, Montréal, Canada
| | - Christine Des Rosiers
- Montreal Heart Institute, Montreal, Canada
- Department of Nutrition, Faculty of Medicine, Université de Montréal, Montreal, Canada
- * E-mail:
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Nozuma S, Okamoto Y, Higuchi I, Yuan J, Hashiguchi A, Sakiyama Y, Yoshimura A, Higuchi Y, Takashima H. Clinical and Electron Microscopic Findings in Two Patients with Mitochondrial Myopathy Associated with Episodic Hyper-creatine Kinase-emia. Intern Med 2015; 54:3209-14. [PMID: 26666615 DOI: 10.2169/internalmedicine.54.5444] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mitochondrial myopathy with episodic hyper-creatine kinase (CK)-emia (MIMECK) is a new disease entity characterized by episodic or persistent muscle weakness and elevated CK levels. We herein report two cases of MIMECK with the findings of histopathological studies. Histopathological examinations revealed strongly succinate dehydrogenase-reactive vessels. Electron microscopy showed abnormal mitochondria in the vessels and proliferating and vacuolated mitochondria under the sarcolemma. Both patients exhibited recurrent severe myalgia, weakness and increased CK levels. L-arginine treatment significantly ameliorated their muscle symptoms. These findings indicate that mitochondrial angiopathy plays an important role in the pathophysiology of MIMECK. L-arginine may be a potential therapeutic agent for this disorder.
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Affiliation(s)
- Satoshi Nozuma
- Department of Neurology and Geriatrics, Kagoshima University Graduate School of Medical and Dental Sciences, Japan
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36
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Abstract
Coenzyme Q10 (CoQ10), also known as ubiquinone or ubidecarenone, is a powerful, endogenously produced, intracellularly existing lipophilic antioxidant. It combats reactive oxygen species (ROS) known to be responsible for a variety of human pathological conditions. Its target site is the inner mitochondrial membrane (IMM) of each cell. In case of deficiency and/or aging, CoQ10 oral supplementation is warranted. However, CoQ10 has low oral bioavailability due to its lipophilic nature, large molecular weight, regional differences in its gastrointestinal permeability and involvement of multitransporters. Intracellular delivery and mitochondrial target ability issues pose additional hurdles. To maximize CoQ10 delivery to its biopharmaceutical target, numerous approaches have been undertaken. The review summaries the current research on CoQ10 bioavailability and highlights the headways to obtain a satisfactory intracellular and targeted mitochondrial delivery. Unresolved questions and research gaps were identified to bring this promising natural product to the forefront of therapeutic agents for treatment of different pathologies.
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Affiliation(s)
- Noha M Zaki
- a Toronto Health Economics and Technology Assessment (THETA) Collaborative Leslie Dan Faculty of Pharmacy, University of Toronto , Toronto , Ontario , Canada
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37
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Parikh S, Goldstein A, Koenig MK, Scaglia F, Enns GM, Saneto R, Anselm I, Cohen BH, Falk MJ, Greene C, Gropman AL, Haas R, Hirano M, Morgan P, Sims K, Tarnopolsky M, Van Hove JLK, Wolfe L, DiMauro S. Diagnosis and management of mitochondrial disease: a consensus statement from the Mitochondrial Medicine Society. Genet Med 2014; 17:689-701. [PMID: 25503498 DOI: 10.1038/gim.2014.177] [Citation(s) in RCA: 333] [Impact Index Per Article: 33.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2014] [Accepted: 11/06/2014] [Indexed: 12/13/2022] Open
Abstract
PURPOSE The purpose of this statement is to review the literature regarding mitochondrial disease and to provide recommendations for optimal diagnosis and treatment. This statement is intended for physicians who are engaged in diagnosing and treating these patients. METHODS The Writing Group members were appointed by the Mitochondrial Medicine Society. The panel included members with expertise in several different areas. The panel members utilized a comprehensive review of the literature, surveys, and the Delphi method to reach consensus. We anticipate that this statement will need to be updated as the field continues to evolve. RESULTS Consensus-based recommendations are provided for the diagnosis and treatment of mitochondrial disease. CONCLUSION The Delphi process enabled the formation of consensus-based recommendations. We hope that these recommendations will help standardize the evaluation, diagnosis, and care of patients with suspected or demonstrated mitochondrial disease.
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Affiliation(s)
- Sumit Parikh
- Department of Neurology, Center for Child Neurology, Cleveland Clinic Children's Hospital, Cleveland, Ohio, USA
| | - Amy Goldstein
- Department of Pediatrics, Division of Child Neurology, Children's Hospital of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Mary Kay Koenig
- Department of Pediatrics, Division of Child and Adolescent Neurology, University of Texas Medical School at Houston, Houston, Texas, USA
| | - Fernando Scaglia
- Department of Molecular and Human Genetics, Baylor College of Medicine and Texas Children's Hospital, Houston, Texas, USA
| | - Gregory M Enns
- Department of Pediatrics, Division of Medical Genetics, Stanford University Lucile Packard Children's Hospital, Palo Alto, California, USA
| | - Russell Saneto
- Department of Neurology, Seattle Children's Hospital, University of Washington, Seattle, Washington, USA.,Department of Pediatrics, Seattle Children's Hospital, University of Washington, Seattle, Washington, USA
| | - Irina Anselm
- Department of Neurology, Boston Children's Hospital, Boston, Massachusetts, USA
| | - Bruce H Cohen
- Department of Pediatrics, NeuroDevelopmental Science Center, Children's Hospital Medical Center of Akron, Akron, Ohio, USA
| | - Marni J Falk
- Division of Human Genetics, Department of Pediatrics, The Children's Hospital of Philadelphia and University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA
| | - Carol Greene
- Department of Pediatrics, University of Maryland Medical Center, Baltimore, Maryland, USA
| | - Andrea L Gropman
- Department of Neurology, Children's National Medical Center and the George Washington University of the Health Sciences, Washington, DC, USA
| | - Richard Haas
- Department of Neurosciences and Pediatrics, UCSD Medical Center and Rady Children's Hospital San Diego, La Jolla, California, USA
| | - Michio Hirano
- Department of Neurology, Columbia University Medical Center, New York, New York, USA
| | - Phil Morgan
- Department of Anesthesiology, Seattle Children's Hospital, Seattle, Washington, USA
| | - Katherine Sims
- Department of Neurology, Harvard Medical School and Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Mark Tarnopolsky
- Department of Pediatrics and Medicine, McMaster University, Hamilton, Ontario, Canada
| | - Johan L K Van Hove
- Department of Pediatrics, Clinical Genetics and Metabolism, Children's Hospital Colorado, Denver, Colorado, USA
| | - Lynne Wolfe
- National Institutes of Health, Bethesda, Maryland, USA
| | - Salvatore DiMauro
- Department of Neurology, Columbia University Medical Center, New York, New York, USA
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38
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Abstract
Although mitochondrial disorders are among the most common inherited conditions that cause neurologic impairment, there are currently no U.S. Food and Drug Administration (FDA)-approved medications designed to treat primary mitochondrial disease. This is in part related to the lack of biomarkers to monitor disease status or response to treatment and the paucity of randomized, controlled clinical trials focused on mitochondrial disease therapies. Despite this discouraging historical precedent, a number of new approaches to mitochondrial disease therapy are on the horizon. By studying metabolites central to redox chemistry, investigators are gaining new insights into potential noninvasive biomarkers. Controlled clinical trials designed to study the effects of novel redox-modulating therapies, such as EPI-743, in patients with inherited mitochondrial disease are also underway. Furthermore, several new compounds with potential effects on inner mitochondrial membrane function and mitochondrial biogenesis are in development. Such advances are providing the foundation for a new era in mitochondrial disease therapeutics.
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Affiliation(s)
- Gregory M Enns
- Department of Pediatrics, Division of Medical Genetics, Stanford University and the Lucile Packard Children's Hospital, Stanford, CA, USA
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39
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Wilnai Y, Enns GM, Niemi AK, Higgins J, Vogel H. Abnormal hepatocellular mitochondria in methylmalonic acidemia. Ultrastruct Pathol 2014; 38:309-14. [PMID: 24933007 DOI: 10.3109/01913123.2014.921657] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Methylmalonic acidemia (MMA) is one of the most frequently encountered forms of branched-chain organic acidemias. Biochemical abnormalities seen in some MMA patients, such as lactic acidemia and increased tricarboxylic acid cycle intermediate excretion, suggest mitochondrial dysfunction. In order to investigate the possibility of mitochondrial involvement in MMA, we examined liver tissue for evidence of mitochondrial ultrastructural abnormalities. Five explanted livers obtained from MMA mut(0) patients undergoing liver transplantation were biopsied. All patients had previous episodes of metabolic acidosis, lactic acidemia, ketonuria, and hyperammonemia. All biopsies revealed a striking mitochondriopathy by electron microscopy. Mitochondria were markedly variable in size, shape, and conformation of cristae. The inner matrix appeared to be greatly expanded and the cristae were diminutive and disconnected. No crystalloid inclusions were noted. This series clearly documents extensive mitochondrial ultrastructure abnormalities in liver samples from MMA patients undergoing transplantation, providing pathological evidence for mitochondrial dysfunction in the pathophysiology of MMA mut(0). Considering the trend to abnormally large mitochondria, the metabolic effects of MMA may restrict mitochondrial fission or promote fusion. The correlation between mitochondrial dysfunction and morphological abnormalities in MMA may provide insights for better understanding and monitoring of optimized or novel therapeutic strategies.
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Affiliation(s)
- Yael Wilnai
- Department of Pediatrics, Division of Medical Genetics, Lucile Packard Children's Hospital, Stanford University Medical Center , Palo Alto, CA , USA and
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Huang WY, Jou MJ, Peng TI. Hypoxic preconditioning-induced mitochondrial protection is not disrupted in a cell model of mtDNA T8993G mutation-induced F1F0-ATP synthase defect: the role of mitochondrial permeability transition. Free Radic Biol Med 2014; 67:314-29. [PMID: 24291231 DOI: 10.1016/j.freeradbiomed.2013.11.019] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2013] [Revised: 10/24/2013] [Accepted: 11/21/2013] [Indexed: 10/26/2022]
Abstract
Transient opening of the mitochondrial permeability transition pore plays a crucial role in hypoxic preconditioning-induced protection. Recently, the cyclophilin-D component of the mitochondrial permeability transition pore has been shown to interact with and regulate the F1F0-ATP synthase. However, the precise role of the F1F0-ATP synthase and the interaction between cyclophilin-D and F1F0-ATP synthase in the mitochondrial permeability transition pore and hypoxic preconditioning remain uncertain. Here we found that a 1-h hypoxic preconditioning delayed apoptosis and improved cell survival after stimulation with various apoptotic inducers including H2O2, ionomycin, and arachidonic acid in mitochondrial DNA T8993G mutation (NARP) osteosarcoma 143B cybrids, an F1F0-ATP synthase defect cell model. This hypoxic preconditioning protected NARP cybrid cells against focal laser irradiation-induced oxidative stress by suppressing reactive oxygen species formation and preventing the depletion of cardiolipin. Furthermore, the protective functions of transient opening of the mitochondrial permeability transition pore in both NARP cybrids and wild-type 143B cells can be augmented by hypoxic preconditioning. Disruption of the interaction between cyclophilin-D and F1F0-ATP synthase by cyclosporin A attenuated the mitochondrial protection induced by hypoxic preconditioning in both NARP cybrids and wild-type 143B cells. Our results demonstrate that the interaction between cyclophilin-D and F1F0-ATP synthase is important in the hypoxic preconditioning-induced cell protection. This finding improves our understanding of the mechanism of mitochondrial permeability transition pore opening in cells in response to hypoxic preconditioning, and will be helpful in further developing new pharmacological agents targeting hypoxia-reoxygenation injury and mitochondria-mediated cell death.
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Affiliation(s)
- Wen-Yi Huang
- Graduate Institute of Clinical Medical Sciences, College of Medicine, Chang Gung University, Kwei-Shan, Tao-Yuan 333, Taiwan; Department of Neurology, Chang Gung Memorial Hospital, Keelung Branch, Keelung 204, Taiwan
| | - Mei-Jie Jou
- Department of Physiology and Pharmacology, and Chang Gung University, Kwei-Shan, Tao-Yuan 333, Taiwan
| | - Tsung-I Peng
- Department of Neurology, Chang Gung Memorial Hospital, Keelung Branch, Keelung 204, Taiwan; Department of Medicine, College of Medicine, Chang Gung University, Kwei-Shan, Tao-Yuan 333, Taiwan.
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41
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Pathological Mutations of the Mitochondrial Human Genome: the Instrumental Role of the Yeast S. cerevisiae. Diseases 2014. [DOI: 10.3390/diseases2010024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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Khrapko K, Turnbull D. Mitochondrial DNA mutations in aging. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2014; 127:29-62. [PMID: 25149213 DOI: 10.1016/b978-0-12-394625-6.00002-7] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The relationship of mitochondrial DNA mutations to aging is still debated. Most mtDNA mutations are recessive: there are multiple copies per cell and mutation needs to clonally expand to cause respiratory deficiency. Overall mtDNA mutant loads are low, so effects of mutations are limited to critical areas where mutations locally reach high fractions. This includes respiratory chain deficient zones in muscle fibers, respiratory-deficient crypts in colon, and massive expansions of deleted mtDNA in substantia nigra neurons. mtDNA "mutator" mouse with increased rate of mtDNA mutations is a useful model, although rates and distribution of mutations may significantly deviate from what is observed in human aging. Comparison of species with different longevity reveals intriguing longevity-related traits in mtDNA sequence, although their significance is yet to be evaluated. The impact of somatic mtDNA mutations rapidly increases with age, so their importance is expected to grow as human life expectancy increases.
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Affiliation(s)
- Konstantin Khrapko
- Harvard Medical School, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA
| | - Doug Turnbull
- LLHW Centre for Ageing and Vitality, Newcastle University, Newcastle, United Kingdom
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43
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Garrido-Maraver J, Cordero MD, Moñino ID, Pereira-Arenas S, Lechuga-Vieco AV, Cotán D, De la Mata M, Oropesa-Ávila M, De Miguel M, Bautista Lorite J, Rivas Infante E, Alvarez-Dolado M, Navas P, Jackson S, Francisci S, Sánchez-Alcázar JA. Screening of effective pharmacological treatments for MELAS syndrome using yeasts, fibroblasts and cybrid models of the disease. Br J Pharmacol 2013; 167:1311-28. [PMID: 22747838 DOI: 10.1111/j.1476-5381.2012.02086.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND AND PURPOSE MELAS (mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes) is a mitochondrial disease most usually caused by point mutations in tRNA genes encoded by mitochondrial DNA (mtDNA). Approximately 80% of cases of MELAS syndrome are associated with a m.3243A > G mutation in the MT-TL1 gene, which encodes the mitochondrial tRNALeu (UUR). Currently, no effective treatments are available for this chronic progressive disorder. Treatment strategies in MELAS and other mitochondrial diseases consist of several drugs that diminish the deleterious effects of the abnormal respiratory chain function, reduce the presence of toxic agents or correct deficiencies in essential cofactors. EXPERIMENTAL APPROACH We evaluated the effectiveness of some common pharmacological agents that have been utilized in the treatment of MELAS, in yeast, fibroblast and cybrid models of the disease. The yeast model harbouring the A14G mutation in the mitochondrial tRNALeu(UUR) gene, which is equivalent to the A3243G mutation in humans, was used in the initial screening. Next, the most effective drugs that were able to rescue the respiratory deficiency in MELAS yeast mutants were tested in fibroblasts and cybrid models of MELAS disease. KEY RESULTS According to our results, supplementation with riboflavin or coenzyme Q(10) effectively reversed the respiratory defect in MELAS yeast and improved the pathologic alterations in MELAS fibroblast and cybrid cell models. CONCLUSIONS AND IMPLICATIONS Our results indicate that cell models have great potential for screening and validating the effects of novel drug candidates for MELAS treatment and presumably also for other diseases with mitochondrial impairment.
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Affiliation(s)
- Juan Garrido-Maraver
- Centro Andaluz de Biología del Desarrollo (CABD) and Centro de Investigación Biomédica en Red: Enfermedades Raras (CIBERER), Instituto de Salud Carlos III, Universidad Pablo de Olavide-Consejo Superior de Investigaciones Científicas-Junta de Andalucía, Sevilla, Spain
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44
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Kraytsberg Y, Nicholas A, Khrapko K. Are somatic mitochondrial DNA mutations relevant to our health? A challenge for mutation analysis techniques. ACTA ACUST UNITED AC 2013; 1:109-16. [PMID: 23489273 DOI: 10.1517/17530059.1.1.109] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
A role of somatic mitochondrial (mt)DNA mutations in ageing and degenerative diseases was postulated decades ago, but this hypothesis remains untested. A substantial number of genetically engineered 'mutator' mouse lines with increased mtDNA mutation rates were expected to test the hypothesis. However, the results of mutator experiments are inconclusive and their interpretations are often contradictory. The authors argue that the problem, to a great extent, is the absence of a universally accepted accurate methodology of mtDNA mutational analysis and hence the lack of consensus with respect to the actual fractions of mtDNA mutations. Estimates by different existing methods vary by more than two orders of magnitude and the reason for this enormous discrepancy has yet to be fully accounted for. Furthermore, studies usually lack the vitally important details, such as the analysis of individual cells and multiple cell types, which is indispensable for rigorous evaluation of the impact of mtDNA mutations. New methods capable of accurate and detailed mutational analysis of mtDNA are in great need. A cell-by-cell mutational analysis may offer a solution.
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45
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Abstract
Mutations in the human mitochondrial genome are known to cause an array of diverse disorders, most of which are maternally inherited, and all of which are associated with defects in oxidative energy metabolism. It is now emerging that somatic mutations in mitochondrial DNA (mtDNA) are also linked to other complex traits, including neurodegenerative diseases, ageing and cancer. Here we discuss insights into the roles of mtDNA mutations in a wide variety of diseases, highlighting the interesting genetic characteristics of the mitochondrial genome and challenges in studying its contribution to pathogenesis.
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46
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Cruz-Torres V, Vázquez-Acevedo M, García-Villegas R, Pérez-Martínez X, Mendoza-Hernández G, González-Halphen D. The cytosol-synthesized subunit II (Cox2) precursor with the point mutation W56R is correctly processed in yeast mitochondria to rescue cytochrome oxidase. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2012; 1817:2128-39. [PMID: 22985601 DOI: 10.1016/j.bbabio.2012.09.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2012] [Revised: 09/01/2012] [Accepted: 09/07/2012] [Indexed: 01/07/2023]
Abstract
Deletion of the yeast mitochondrial gene COX2 encoding subunit 2 (Cox2) of cytochrome c oxidase (CcO) results in loss of respiration (Δcox2 strain). Supekova et al. (2010) [1] transformed a Δcox2 strain with a vector expressing Cox2 with a mitochondrial targeting sequence (MTS) and the point mutation W56R (Cox2(W56R)), restoring respiratory growth. Here, the CcO carrying the allotopically-expressed Cox2(W56R) was characterized. Yeast mitochondria from the wild-type (WT) and the Δcox2+Cox2(W56R) strains were subjected to Blue Native electrophoresis. In-gel activity of CcO and spectroscopic quantitation of cytochromes revealed that only 60% of CcO is present in the complemented strain, and that less CcO is found associated in supercomplexes as compared to WT. CcOs from the WT and the mutant exhibited similar subunit composition, although activity was 20-25% lower in the enzyme containing Cox2(W56R) than in the one with Cox2(WT). Tandem mass spectrometry confirmed that W(56) was substituted by R(56) in Cox2(W56R). In addition, Cox2(W56R) exhibited the same N-terminus than Cox2(WT), indicating that the MTS of Oxa1 and the leader sequence of 15 residues were removed from Cox2(W56R) during maturation. Thus, Cox2(W56R) is identical to Cox2(WT) except for the point mutation W56R. Mitochondrial Cox1 synthesis is strongly reduced in Δcox2 mutants, but the Cox2(W56R) complemented strain led to full restoration of Cox1 synthesis. We conclude that the cytosol-synthesized Cox2(W56R) follows a rate-limiting process of import, maturation or assembly that yields lower steady-state levels of CcO. Still, the allotopically-expressed Cox2(W56R) restores CcO activity and allows mitochondrial Cox1 synthesis to advance at WT levels.
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Affiliation(s)
- Valentín Cruz-Torres
- Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, México D.F., Mexico
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47
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Carrillo-Cázares TA, Torres-García E. Monte Carlo mitochondrial dosimetry and microdosimetry of 131I. RADIATION PROTECTION DOSIMETRY 2012; 153:411-416. [PMID: 22826354 DOI: 10.1093/rpd/ncs132] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
A mitochondrion is an organelle found in most eukaryotic cells, which produces most of the energy needed by a living cell. It has been shown that ionising radiation causes mitochondrial damage leading to apoptosis or cell death. The aim of this work was to calculate, by Monte Carlo simulation, the specific energy (z) into the mitochondria, due to Auger electrons, conversion electrons and beta emission from (131)I, where the radionuclide was carried by a vector to the cell surface and the surrounding environment. A concentric spherical geometry represents a cell and its nucleus. Three different volumes were used to represent the mitochondria; they were placed in random positions within the cytoplasm. The z produced by a single event is due to low-energy electrons (76 %) and beta particles (24 %) and the mitochondria receive a total mean z two orders of magnitude higher than that of the cell nucleus.
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Affiliation(s)
- Tomás A Carrillo-Cázares
- Laboratorio de Simulación Monte Carlo, Coordinación de Posgrado, Facultad de Medicina, Universidad Autónoma del Estado de México, Paseo Tollocan s/n, esquina Jesús Carranza, Colonia Moderna de la Cruz, Toluca, Estado de México, México
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48
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Abstract
Considerable research has been conducted on mitochondrial biology as it pertains to aging. However, relatively little attention has been accorded the pyruvate dehydrogenase complex (PDC) relative to how we grow old and acquire age-related diseases. The purpose of this review is threefold: first, to describe the physiological chemistry of the PDC and define its place in normal cellular bioenergetics; second, to compare and contrast the pathogenesis and clinical features of congenital PDC deficiency with discrete examples of age-associated dysfunction of the complex; and third, to summarize recent findings in Caenorhabditis elegans that shed additional new light on the significance of the PDC to the aging process.
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Affiliation(s)
- Peter W Stacpoole
- Departments of Medicine (Division of Endocrinology and Metabolism) and Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, FL 32611, USA.
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49
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Cho YM, Kim JH, Kim M, Park SJ, Koh SH, Ahn HS, Kang GH, Lee JB, Park KS, Lee HK. Mesenchymal stem cells transfer mitochondria to the cells with virtually no mitochondrial function but not with pathogenic mtDNA mutations. PLoS One 2012; 7:e32778. [PMID: 22412925 PMCID: PMC3295770 DOI: 10.1371/journal.pone.0032778] [Citation(s) in RCA: 131] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2011] [Accepted: 01/31/2012] [Indexed: 11/25/2022] Open
Abstract
It has been reported that human mesenchymal stem cells (MSCs) can transfer mitochondria to the cells with severely compromised mitochondrial function. We tested whether the reported intercellular mitochondrial transfer could be replicated in different types of cells or under different experimental conditions, and tried to elucidate possible mechanism. Using biochemical selection methods, we found exponentially growing cells in restrictive media (uridine− and bromodeoxyuridine [BrdU]+) during the coculture of MSCs (uridine-independent and BrdU-sensitive) and 143B-derived cells with severe mitochondrial dysfunction induced by either long-term ethidium bromide treatment or short-term rhodamine 6G (R6G) treatment (uridine-dependent but BrdU-resistant). The exponentially growing cells had nuclear DNA fingerprint patterns identical to 143B, and a sequence of mitochondrial DNA (mtDNA) identical to the MSCs. Since R6G causes rapid and irreversible damage to mitochondria without the removal of mtDNA, the mitochondrial function appears to be restored through a direct transfer of mitochondria rather than mtDNA alone. Conditioned media, which were prepared by treating mtDNA-less 143B ρ0 cells under uridine-free condition, induced increased chemotaxis in MSC, which was also supported by transcriptome analysis. Cytochalasin B, an inhibitor of chemotaxis and cytoskeletal assembly, blocked mitochondrial transfer phenomenon in the above condition. However, we could not find any evidence of mitochondrial transfer to the cells harboring human pathogenic mtDNA mutations (A3243G mutation or 4,977 bp deletion). Thus, the mitochondrial transfer is limited to the condition of a near total absence of mitochondrial function. Elucidation of the mechanism of mitochondrial transfer will help us create a potential cell therapy-based mitochondrial restoration or mitochondrial gene therapy for human diseases caused by mitochondrial dysfunction.
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Affiliation(s)
- Young Min Cho
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, South Korea
- * E-mail:
| | - Ju Han Kim
- Department of Biomedical Informatics, Seoul National University Biomedical Informatics (SNUBI) and Interdisciplinary Program of Medical Informatics, Seoul, South Korea
| | - Mingoo Kim
- Department of Biomedical Informatics, Seoul National University Biomedical Informatics (SNUBI) and Interdisciplinary Program of Medical Informatics, Seoul, South Korea
| | - Su Jin Park
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, South Korea
| | - Sang Hyeok Koh
- Department of Pediatrics, Seoul National University College of Medicine, Seoul, South Korea
| | - Hyo Seop Ahn
- Department of Pediatrics, Seoul National University College of Medicine, Seoul, South Korea
| | - Gyeong Hoon Kang
- Department of Pathology, Seoul National University College of Medicine, Seoul, South Korea
| | - Jung-Bin Lee
- Department of Forensic Medicine, Seoul National University College of Medicine, Seoul, South Korea
| | - Kyong Soo Park
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, South Korea
| | - Hong Kyu Lee
- Department of Internal Medicine, Eulji University College of Medicine, Seoul, South Korea
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50
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Jonckheere AI, Smeitink JAM, Rodenburg RJT. Mitochondrial ATP synthase: architecture, function and pathology. J Inherit Metab Dis 2012; 35:211-25. [PMID: 21874297 PMCID: PMC3278611 DOI: 10.1007/s10545-011-9382-9] [Citation(s) in RCA: 382] [Impact Index Per Article: 31.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/20/2011] [Revised: 07/22/2011] [Accepted: 07/27/2011] [Indexed: 12/16/2022]
Abstract
Human mitochondrial (mt) ATP synthase, or complex V consists of two functional domains: F(1), situated in the mitochondrial matrix, and F(o), located in the inner mitochondrial membrane. Complex V uses the energy created by the proton electrochemical gradient to phosphorylate ADP to ATP. This review covers the architecture, function and assembly of complex V. The role of complex V di-and oligomerization and its relation with mitochondrial morphology is discussed. Finally, pathology related to complex V deficiency and current therapeutic strategies are highlighted. Despite the huge progress in this research field over the past decades, questions remain to be answered regarding the structure of subunits, the function of the rotary nanomotor at a molecular level, and the human complex V assembly process. The elucidation of more nuclear genetic defects will guide physio(patho)logical studies, paving the way for future therapeutic interventions.
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Affiliation(s)
- An I. Jonckheere
- Department of Pediatrics, Nijmegen Center for Mitochondrial Disorders, 656 Laboratory for Genetic, Endocrine, and Metabolic Disorders, Radboud University Nijmegen Medical Center, PO Box 9101, 6500 HB Nijmegen, The Netherlands
| | - Jan A. M. Smeitink
- Department of Pediatrics, Nijmegen Center for Mitochondrial Disorders, 656 Laboratory for Genetic, Endocrine, and Metabolic Disorders, Radboud University Nijmegen Medical Center, PO Box 9101, 6500 HB Nijmegen, The Netherlands
| | - Richard J. T. Rodenburg
- Department of Pediatrics, Nijmegen Center for Mitochondrial Disorders, 656 Laboratory for Genetic, Endocrine, and Metabolic Disorders, Radboud University Nijmegen Medical Center, PO Box 9101, 6500 HB Nijmegen, The Netherlands
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