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Watson-Fargie T, Marshall V, Fullerton NE, Leach V, Pilz D, Hemingbrough CVY, Hopton S, Taylor RW, Ng YS, Schaefer A, Gorman GS, Farrugia ME. Leigh syndrome: an adult presentation of a paediatric disease. Pract Neurol 2024; 24:45-50. [PMID: 37567761 DOI: 10.1136/pn-2023-003862] [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] [Accepted: 07/23/2023] [Indexed: 08/13/2023]
Abstract
A previously healthy 27-year-old man was admitted to the acute neurology ward with events involving his face, throat and upper limb, which video telemetry later confirmed were refractory focal seizures. He also had progressive pyramidal features, dysarthria and ataxia. MR scans of the brain identified progressive bilateral basal ganglia abnormalities, consistent with Leigh syndrome. However, extensive laboratory and genetic panels did not give a unifying diagnosis. A skeletal muscle biopsy showed no histopathological abnormalities on routine stains. Sequencing of the entire mitochondrial genome in skeletal muscle identified a well-characterised pathogenic variant (m.10191T>C in MT-ND3; NC_012920.1) at 85% heteroplasmy in skeletal muscle. We discuss the clinical and molecular diagnosis of an adult presenting with Leigh syndrome, which is more commonly a paediatric presentation of mitochondrial disease, and how early recognition of a mitochondrial cause is important to support patient care.
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Affiliation(s)
| | | | | | - Veronica Leach
- Neurophysiology, Institute of Neurological Sciences, Glasgow, UK
| | - Daniela Pilz
- West of Scotland Genomics Service, Queen Elizabeth University Hospital, Glasgow, UK
| | - Charlotte V Y Hemingbrough
- NHS Highly Specialised Service for Rare Mitochondrial Disorders, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, UK
| | - Sila Hopton
- NHS Highly Specialised Service for Rare Mitochondrial Disorders, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, UK
| | - Robert W Taylor
- NHS Highly Specialised Service for Rare Mitochondrial Disorders, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, UK
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, The Medical School, Newcastle University, Newcastle upon Tyne, UK
| | - Yi S Ng
- NHS Highly Specialised Service for Rare Mitochondrial Disorders, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, UK
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, The Medical School, Newcastle University, Newcastle upon Tyne, UK
| | - Andrew Schaefer
- NHS Highly Specialised Service for Rare Mitochondrial Disorders, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, UK
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, The Medical School, Newcastle University, Newcastle upon Tyne, UK
| | - Gráinne S Gorman
- NHS Highly Specialised Service for Rare Mitochondrial Disorders, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, UK
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, The Medical School, Newcastle University, Newcastle upon Tyne, UK
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2
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Meshrkey F, Scheulin KM, Littlejohn CM, Stabach J, Saikia B, Thorat V, Huang Y, LaFramboise T, Lesnefsky EJ, Rao RR, West FD, Iyer S. Induced pluripotent stem cells derived from patients carrying mitochondrial mutations exhibit altered bioenergetics and aberrant differentiation potential. Stem Cell Res Ther 2023; 14:320. [PMID: 37936209 PMCID: PMC10631039 DOI: 10.1186/s13287-023-03546-7] [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: 05/17/2023] [Accepted: 10/25/2023] [Indexed: 11/09/2023] Open
Abstract
BACKGROUND Human mitochondrial DNA mutations are associated with common to rare mitochondrial disorders, which are multisystemic with complex clinical pathologies. The pathologies of these diseases are poorly understood and have no FDA-approved treatments leading to symptom management. Leigh syndrome (LS) is a pediatric mitochondrial disorder that affects the central nervous system during early development and causes death in infancy. Since there are no adequate models for understanding the rapid fatality associated with LS, human-induced pluripotent stem cell (hiPSC) technology has been recognized as a useful approach to generate patient-specific stem cells for disease modeling and understanding the origins of the phenotype. METHODS hiPSCs were generated from control BJ and four disease fibroblast lines using a cocktail of non-modified reprogramming and immune evasion mRNAs and microRNAs. Expression of hiPSC-associated intracellular and cell surface markers was identified by immunofluorescence and flow cytometry. Karyotyping of hiPSCs was performed with cytogenetic analysis. Sanger and next-generation sequencing were used to detect and quantify the mutation in all hiPSCs. The mitochondrial respiration ability and glycolytic function were measured by the Seahorse Bioscience XFe96 extracellular flux analyzer. RESULTS Reprogrammed hiPSCs expressed pluripotent stem cell markers including transcription factors POU5F1, NANOG and SOX2 and cell surface markers SSEA4, TRA-1-60 and TRA-1-81 at the protein level. Sanger sequencing analysis confirmed the presence of mutations in all reprogrammed hiPSCs. Next-generation sequencing demonstrated the variable presence of mutant mtDNA in reprogrammed hiPSCs. Cytogenetic analyses confirmed the presence of normal karyotype in all reprogrammed hiPSCs. Patient-derived hiPSCs demonstrated decreased maximal mitochondrial respiration, while mitochondrial ATP production was not significantly different between the control and disease hiPSCs. In line with low maximal respiration, the spare respiratory capacity was lower in all the disease hiPSCs. The hiPSCs also demonstrated neural and cardiac differentiation potential. CONCLUSION Overall, the hiPSCs exhibited variable mitochondrial dysfunction that may alter their differentiation potential and provide key insights into clinically relevant developmental perturbations.
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Affiliation(s)
- Fibi Meshrkey
- Department of Biological Sciences, J. William Fulbright College of Arts and Sciences, University of Arkansas, Science and Engineering 601, Fayetteville, AR, 72701, USA
- Cell and Molecular Biology Program, University of Arkansas, Fayetteville, AR, USA
- Department of Histology and Cell Biology, Faculty of Medicine, Alexandria University, Alexandria, Egypt
| | - Kelly M Scheulin
- Regenerative Bioscience Center, University of Georgia, Athens, GA, USA
- Department of Animal and Dairy Science, University of Georgia, Athens, GA, USA
- Neuroscience Program, Biomedical and Health Sciences Institute, University of Georgia, Athens, GA, USA
| | - Christopher M Littlejohn
- Regenerative Bioscience Center, University of Georgia, Athens, GA, USA
- Department of Animal and Dairy Science, University of Georgia, Athens, GA, USA
| | - Joshua Stabach
- Department of Biological Sciences, J. William Fulbright College of Arts and Sciences, University of Arkansas, Science and Engineering 601, Fayetteville, AR, 72701, USA
| | - Bibhuti Saikia
- Department of Biological Sciences, J. William Fulbright College of Arts and Sciences, University of Arkansas, Science and Engineering 601, Fayetteville, AR, 72701, USA
| | - Vedant Thorat
- Department of Genetics and Genome Sciences, Case Western Reserve University School of Medicine, Cleveland, OH, USA
| | - Yimin Huang
- Department of Genetics and Genome Sciences, Case Western Reserve University School of Medicine, Cleveland, OH, USA
| | - Thomas LaFramboise
- Department of Genetics and Genome Sciences, Case Western Reserve University School of Medicine, Cleveland, OH, USA
| | - Edward J Lesnefsky
- Department of Physiology and Biophysics, Virginia Commonwealth University, Richmond, VA, USA
- Cardiology Section Medical Service, McGuire Veterans Affairs Medical Center, Richmond, VA, USA
- Department of Biochemistry and Molecular Biology, Virginia Commonwealth University, Richmond, VA, USA
- Division of Cardiology, Department of Internal Medicine, Pauley Heart Center, Virginia Commonwealth University, Richmond, VA, USA
| | - Raj R Rao
- Department of Biomedical Engineering, College of Engineering, University of Arkansas, Fayetteville, AR, USA
| | - Franklin D West
- Regenerative Bioscience Center, University of Georgia, Athens, GA, USA
- Department of Animal and Dairy Science, University of Georgia, Athens, GA, USA
- Neuroscience Program, Biomedical and Health Sciences Institute, University of Georgia, Athens, GA, USA
| | - Shilpa Iyer
- Department of Biological Sciences, J. William Fulbright College of Arts and Sciences, University of Arkansas, Science and Engineering 601, Fayetteville, AR, 72701, USA.
- Cell and Molecular Biology Program, University of Arkansas, Fayetteville, AR, USA.
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3
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Amore G, Vacchiano V, La Morgia C, Valentino ML, Caporali L, Fiorini C, Ormanbekova D, Salvi F, Bartoletti-Stella A, Capellari S, Liguori R, Carelli V. Co-occurrence of amyotrophic lateral sclerosis and Leber's hereditary optic neuropathy: is mitochondrial dysfunction a modifier? J Neurol 2023; 270:559-564. [PMID: 36066624 PMCID: PMC9813087 DOI: 10.1007/s00415-022-11355-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Revised: 08/24/2022] [Accepted: 08/25/2022] [Indexed: 01/09/2023]
Affiliation(s)
- Giulia Amore
- Department of Biomedical and Neuromotor Sciences (DIBINEM), University of Bologna, Bologna, Italy
| | - Veria Vacchiano
- Department of Biomedical and Neuromotor Sciences (DIBINEM), University of Bologna, Bologna, Italy.,IRCCS Istituto delle Scienze Neurologiche di Bologna, UOC Clinica Neurologica, Bologna, Italy
| | - Chiara La Morgia
- Department of Biomedical and Neuromotor Sciences (DIBINEM), University of Bologna, Bologna, Italy.,IRCCS Istituto delle Scienze Neurologiche di Bologna, UOC Clinica Neurologica, Bologna, Italy
| | - Maria L Valentino
- Department of Biomedical and Neuromotor Sciences (DIBINEM), University of Bologna, Bologna, Italy.,IRCCS Istituto delle Scienze Neurologiche di Bologna, UOC Clinica Neurologica, Bologna, Italy
| | - Leonardo Caporali
- IRCCS Istituto delle Scienze Neurologiche di Bologna, Programma di Neurogenetica, Bologna, Italy
| | - Claudio Fiorini
- IRCCS Istituto delle Scienze Neurologiche di Bologna, Programma di Neurogenetica, Bologna, Italy
| | - Danara Ormanbekova
- IRCCS Istituto delle Scienze Neurologiche di Bologna, Programma di Neurogenetica, Bologna, Italy
| | - Fabrizio Salvi
- IRCCS Istituto delle Scienze Neurologiche di Bologna, Programma SLA Atassia Amiloidosi e Miastenia, Bologna, Italy
| | - Anna Bartoletti-Stella
- Department of Experimental, Diagnostic and Specialty Medicine, DIMES University of Bologna, Bologna, Italy
| | - Sabina Capellari
- Department of Biomedical and Neuromotor Sciences (DIBINEM), University of Bologna, Bologna, Italy.,IRCCS Istituto delle Scienze Neurologiche di Bologna, Programma di Neurogenetica, Bologna, Italy
| | - Rocco Liguori
- Department of Biomedical and Neuromotor Sciences (DIBINEM), University of Bologna, Bologna, Italy.,IRCCS Istituto delle Scienze Neurologiche di Bologna, UOC Clinica Neurologica, Bologna, Italy
| | - Valerio Carelli
- Department of Biomedical and Neuromotor Sciences (DIBINEM), University of Bologna, Bologna, Italy. .,IRCCS Istituto delle Scienze Neurologiche di Bologna, Programma di Neurogenetica, Bologna, Italy. .,Bellaria Hospital, Via Altura 3, 40139, Bologna, Italy.
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4
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Newstead SM, Finsterer J. Leigh-Like Syndrome With a Novel, Complex Phenotype Due to m.10191T>C in Mt-ND3. Cureus 2022; 14:e28986. [PMID: 36249637 PMCID: PMC9548404 DOI: 10.7759/cureus.28986] [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] [Accepted: 09/09/2022] [Indexed: 11/24/2022] Open
Abstract
Leigh-like syndrome (LLS) due to the variant m.10191T>C in ND3 with a number of new phenotypic traits has not been published. In this case report, a 32-year-old woman diagnosed with Leigh-like syndrome presented with a complex novel, progressive, multisystem phenotype, manifesting in the brain (mild cognitive impairment, seizures, choreoathetosis, pseudotumor cerebri, hypersomnia, symmetric pallidal hypointensities, panda sign, calcifications, dysphagia), endocrine organs (empty sella syndrome, hypocorticism, hypoaldosteronism, hypogonadism), hematopoietic system (anemia, lymphocytosis), immune system (lymphocytosis, hypogammaglobulinemia), gut (reflux, diarrhea), kidneys (renal insufficiency, renal tubular acidosis, nephrolithiasis), muscles (myopathy, exercise intolerance, easy fatigability), peripheral nerves (small fiber neuropathy, dysautonomia), connective tissue (hyperlaxity of joints, bruising), and bones (scoliosis, Chiari malformation). A genetic workup revealed the known pathogenic variant m.10191T>C in ND3, which was also carried by the patient’s mother. This case demonstrates that the m.10191T>C variant in ND3 can phenotypically manifest with multisystem disease and that this disease is responsive to symptomatic treatment and application of additional compounds.
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5
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Na JH, Lee MJ, Lee CH, Lee YM. Association Between Epilepsy and Leigh Syndrome With MT-ND3 Mutation, Particularly the m.10191T>C Point Mutation. Front Neurol 2021; 12:752467. [PMID: 34956047 PMCID: PMC8702430 DOI: 10.3389/fneur.2021.752467] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Accepted: 11/12/2021] [Indexed: 12/12/2022] Open
Abstract
Background and Purpose: Recent advances in molecular genetic testing have led to a rapid increase in the understanding of the genetics of Leigh syndrome. Several studies have suggested that Leigh syndrome with MT-ND3 mutation is strongly associated with epilepsy. This study focused on the epilepsy-related characteristics of Leigh syndrome with MT-ND3 mutation identified in a single tertiary hospital in South Korea. Methods: We selected 31 patients with mitochondrial DNA (mtDNA) mutations who were genetically diagnosed with mtDNA-associated Leigh syndrome. Among them, seven patients with MT-ND3 mutations were detected. We reviewed various clinical findings such as laboratory findings, brain images, electroencephalography data, seizure types, seizure frequency, antiepileptic drug use history, and current seizure status. Results: The nucleotide changes in the seven patients with the Leigh syndrome with MT-ND3 mutation were divided into two groups: m.10191T>C and m.10158T>C. Six of the seven patients were found to have the m.10191T>C mutations. The median value of the mutant load was 82.5%, ranging from 57.9 to 93.6%. No particular tendency was observed for the first symptom or seizure onset or mutant load. The six patients with the m.10191T>C mutation were diagnosed with epilepsy. Three of these patients were diagnosed with Lennox-Gastaut syndrome (LGS). Conclusion: We reported a very strong association between epilepsy and MT-ND3 mutation in Leigh syndrome, particularly the m.10191T>C mutation. The possibility of an association between the epilepsy phenotype of the m.10191T>C mutation and LGS was noted.
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Affiliation(s)
- Ji-Hoon Na
- Department of Pediatrics, Yonsei University College of Medicine, Seoul, South Korea
| | - Min Jung Lee
- Department of Pediatrics, Yonsei University College of Medicine, Seoul, South Korea
| | - Chul Ho Lee
- Department of Pediatrics, Yonsei University College of Medicine, Seoul, South Korea
| | - Young-Mock Lee
- Department of Pediatrics, Yonsei University College of Medicine, Seoul, South Korea.,Epilepsy Research Institute, Yonsei University College of Medicine, Seoul, South Korea
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6
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Meshrkey F, Cabrera Ayuso A, Rao RR, Iyer S. Quantitative analysis of mitochondrial morphologies in human induced pluripotent stem cells for Leigh syndrome. Stem Cell Res 2021; 57:102572. [PMID: 34662843 PMCID: PMC10332439 DOI: 10.1016/j.scr.2021.102572] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Revised: 10/03/2021] [Accepted: 10/11/2021] [Indexed: 01/19/2023] Open
Abstract
Mitochondria are dynamic organelles with wide range of morphologies contributing to regulating different signaling pathways and several cellular functions. Leigh syndrome (LS) is a classic pediatric mitochondrial disorder characterized by complex and variable clinical pathologies, and primarily affects the nervous system during early development. It is important to understand the differences between mitochondrial morphologies in healthy and diseased states so that focused therapies can target the disease during its early stages. In this study, we performed a comprehensive analysis of mitochondrial dynamics in five patient-derived human induced pluripotent stem cells (hiPSCs) containing different mutations associated with LS. Our results suggest that subtle alterations in mitochondrial morphologies are specific to the mtDNA variant. Three out of the five LS-hiPSCs exhibited characteristics consistent with fused mitochondria. To our knowledge, this is the first comprehensive study that quantifies mitochondrial dynamics in hiPSCs specific to mitochondrial disorders. In addition, we observed an overall decrease in mitochondrial membrane potential in all five LS-hiPSCs. A more thorough analysis of the correlations between mitochondrial dynamics, membrane potential dysfunction caused by mutations in the mtDNA in hiPSCs and differentiated derivatives will aid in identifying unique morphological signatures of various mitochondrial disorders during early stages of embryonic development.
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Affiliation(s)
- Fibi Meshrkey
- Department of Biological Sciences, Fulbright College of Arts and Sciences, University of Arkansas, Fayetteville, AR, USA; Cell and Molecular Biology Program, University of Arkansas, Fayetteville, AR, USA; Department of Histology and Cell Biology, Faculty of Medicine, Alexandria University, Egypt
| | - Ana Cabrera Ayuso
- Cell and Molecular Biology Program, University of Arkansas, Fayetteville, AR, USA
| | - Raj R Rao
- Cell and Molecular Biology Program, University of Arkansas, Fayetteville, AR, USA; Department of Biomedical Engineering, College of Engineering, University of Arkansas, Fayetteville, AR, USA
| | - Shilpa Iyer
- Department of Biological Sciences, Fulbright College of Arts and Sciences, University of Arkansas, Fayetteville, AR, USA; Cell and Molecular Biology Program, University of Arkansas, Fayetteville, AR, USA.
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7
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Bakare AB, Lesnefsky EJ, Iyer S. Leigh Syndrome: A Tale of Two Genomes. Front Physiol 2021; 12:693734. [PMID: 34456746 PMCID: PMC8385445 DOI: 10.3389/fphys.2021.693734] [Citation(s) in RCA: 43] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2021] [Accepted: 07/22/2021] [Indexed: 12/21/2022] Open
Abstract
Leigh syndrome is a rare, complex, and incurable early onset (typically infant or early childhood) mitochondrial disorder with both phenotypic and genetic heterogeneity. The heterogeneous nature of this disorder, based in part on the complexity of mitochondrial genetics, and the significant interactions between the nuclear and mitochondrial genomes has made it particularly challenging to research and develop therapies. This review article discusses some of the advances that have been made in the field to date. While the prognosis is poor with no current substantial treatment options, multiple studies are underway to understand the etiology, pathogenesis, and pathophysiology of Leigh syndrome. With advances in available research tools leading to a better understanding of the mitochondria in health and disease, there is hope for novel treatment options in the future.
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Affiliation(s)
- Ajibola B. Bakare
- Department of Biological Sciences, J. William Fulbright College of Arts and Sciences, University of Arkansas, Fayetteville, AR, United States
| | - Edward J. Lesnefsky
- Division of Cardiology, Pauley Heart Center, Department of Internal Medicine, School of Medicine, Virginia Commonwealth University, Richmond, VA, United States
- Department of Physiology/Biophysics, School of Medicine, Virginia Commonwealth University, Richmond, VA, United States
- Department of Biochemistry and Molecular Biology, School of Medicine, Virginia Commonwealth University, Richmond, VA, United States
| | - Shilpa Iyer
- Department of Biological Sciences, J. William Fulbright College of Arts and Sciences, University of Arkansas, Fayetteville, AR, United States
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8
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Spath K, Babariya D, Konstantinidis M, Lowndes J, Child T, Grifo JA, Poulton J, Wells D. Clinical application of sequencing-based methods for parallel preimplantation genetic testing for mitochondrial DNA disease and aneuploidy. Fertil Steril 2021; 115:1521-1532. [PMID: 33745725 DOI: 10.1016/j.fertnstert.2021.01.026] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Revised: 01/15/2021] [Accepted: 01/19/2021] [Indexed: 12/18/2022]
Abstract
OBJECTIVE To validate and apply a strategy permitting parallel preimplantation genetic testing (PGT) for mitochondrial DNA (mtDNA) disease and aneuploidy (PGT-A). DESIGN Preclinical test validation and case reports. SETTING Fertility centers. Diagnostics laboratory. PATIENTS Four patients at risk of transmitting mtDNA disease caused by m.8993T>G (Patients A and B), m.10191T>G (Patient C), and m.3243A>G (Patient D). Patients A, B, and C had affected children. Patients A and D displayed somatic heteroplasmy for mtDNA mutations. INTERVENTIONS Embryo biopsy, genetic testing, and uterine transfer of embryos predicted to be euploid and mutation-free. MAIN OUTCOME MEASURES Test accuracy, treatment outcomes, and mutation segregation. RESULTS Accuracy of mtDNA mutation quantification was confirmed. The test was compatible with PGT-A, and half of the embryos tested were shown to be aneuploid (16/33). Mutations were detected in approximately 40% of embryo biopsies from Patients A and D (10/24) but in none from Patients B and C (n = 29). Patients B and C had healthy children following PGT and natural conception, respectively. The m.8993T>G mutation displayed skewed segregation, whereas m.3243A>G mutation levels were relatively low and potentially impacted embryo development. CONCLUSIONS Considering the high aneuploidy rate, strategies providing a combination of PGT for mtDNA disease and aneuploidy may be advantageous compared with approaches that consider only mtDNA. Heteroplasmic women had a higher incidence of affected embryos than those with undetectable somatic mutant mtDNA but were still able to produce mutation-free embryos. While not conclusive, the results are consistent with the existence of mutation-specific segregation mechanisms occurring during oogenesis and possibly embryogenesis.
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Affiliation(s)
- Katharina Spath
- Nuffield Department of Women's and Reproductive Health, University of Oxford, Oxford, United Kingdom; Juno Genetics, Oxford, United Kingdom.
| | - Dhruti Babariya
- Nuffield Department of Women's and Reproductive Health, University of Oxford, Oxford, United Kingdom; Juno Genetics, Oxford, United Kingdom
| | | | - Jo Lowndes
- Oxford Centre for Genomic Medicine, Oxford University Hospitals NHS Foundation Trust, Nuffield Orthopaedic Centre, Oxford, United Kingdom
| | - Tim Child
- Nuffield Department of Women's and Reproductive Health, University of Oxford, Oxford, United Kingdom; Oxford Fertility, Fertility Partnership, Oxford, United Kingdom
| | | | - Joanna Poulton
- Nuffield Department of Women's and Reproductive Health, University of Oxford, Oxford, United Kingdom
| | - Dagan Wells
- Nuffield Department of Women's and Reproductive Health, University of Oxford, Oxford, United Kingdom; Juno Genetics, Oxford, United Kingdom
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9
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Fernandez-Vizarra E, Zeviani M. Mitochondrial disorders of the OXPHOS system. FEBS Lett 2020; 595:1062-1106. [PMID: 33159691 DOI: 10.1002/1873-3468.13995] [Citation(s) in RCA: 99] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2020] [Revised: 10/21/2020] [Accepted: 11/01/2020] [Indexed: 12/13/2022]
Abstract
Mitochondrial disorders are among the most frequent inborn errors of metabolism, their primary cause being the dysfunction of the oxidative phosphorylation system (OXPHOS). OXPHOS is composed of the electron transport chain (ETC), formed by four multimeric enzymes and two mobile electron carriers, plus an ATP synthase [also called complex V (cV)]. The ETC performs the redox reactions involved in cellular respiration while generating the proton motive force used by cV to synthesize ATP. OXPHOS biogenesis involves multiple steps, starting from the expression of genes encoded in physically separated genomes, namely the mitochondrial and nuclear DNA, to the coordinated assembly of components and cofactors building each individual complex and eventually the supercomplexes. The genetic cause underlying around half of the diagnosed mitochondrial disease cases is currently known. Many of these cases result from pathogenic variants in genes encoding structural subunits or additional factors directly involved in the assembly of the ETC complexes. Here, we review the historical and most recent findings concerning the clinical phenotypes and the molecular pathological mechanisms underlying this particular group of disorders.
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Affiliation(s)
- Erika Fernandez-Vizarra
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, UK
| | - Massimo Zeviani
- Venetian Institute of Molecular Medicine, Padova, Italy.,Department of Neurosciences, University of Padova, Italy
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10
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Naeem MM, Maheshan R, Costford SR, Wahedi A, Trajkovski M, Plavec J, Yatsunyk LA, Ciesielski GL, Kaufman BA, Sondheimer N. G-quadruplex-mediated reduction of a pathogenic mitochondrial heteroplasmy. Hum Mol Genet 2020; 28:3163-3174. [PMID: 31261379 DOI: 10.1093/hmg/ddz153] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Revised: 05/28/2019] [Accepted: 06/21/2019] [Indexed: 12/18/2022] Open
Abstract
Disease-associated variants in mitochondrial DNA (mtDNA) are frequently heteroplasmic, a state of co-existence with the wild-type genome. Because heteroplasmy correlates with the severity and penetrance of disease, improvement in the ratio between these genomes in favor of the wild-type, known as heteroplasmy shifting, is potentially therapeutic. We evaluated known pathogenic mtDNA variants and identified those with the potential for allele-specific differences in the formation of non-Watson-Crick G-quadruplex (GQ) structures. We found that the Leigh syndrome (LS)-associated m.10191C variant promotes GQ formation within local sequence in vitro. Interaction of this sequence with a small molecule GQ-binding agent, berberine hydrochloride, further increased GQ stability. The GQ formed at m.10191C differentially impeded the processivity of the mitochondrial DNA polymerase gamma (Pol γ) in vitro, providing a potential means to favor replication of the wild-type allele. We tested the potential for shifting heteroplasmy through the cyclical application of two different mitochondria-targeted GQ binding compounds in primary fibroblasts from patients with m.10191T>C heteroplasmy. Treatment induced alternating mtDNA depletion and repopulation and was effective in shifting heteroplasmy towards the non-pathogenic allele. Similar treatment of pathogenic heteroplasmies that do not affect GQ formation did not induce heteroplasmy shift. Following treatment, heteroplasmic m.10191T>C cells had persistent improvements and heteroplasmy and a corresponding increase in maximal mitochondrial oxygen consumption. This study demonstrates the potential for using small-molecule GQ-binding agents to induce genetic and functional improvements in m.10191T>C heteroplasmy.
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Affiliation(s)
| | - Rathena Maheshan
- Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, ON, Canada
| | - Sheila R Costford
- Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, ON, Canada
| | - Azizia Wahedi
- Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, ON, Canada
| | - Marko Trajkovski
- National Institute of Chemistry, Slovenian NMR Center, Ljubljana, Slovenia
| | - Janez Plavec
- National Institute of Chemistry, Slovenian NMR Center, Ljubljana, Slovenia
| | - Liliya A Yatsunyk
- Department of Chemistry and Biochemistry, Swarthmore College, Swarthmore PA, USA
| | | | - Brett A Kaufman
- Center for Metabolism and Mitochondrial Medicine, Division of Cardiology, Vascular Medicine Institute, Department of Medicine, University of Pittsburgh Medical School, Pittsburgh, PA, USA
| | - Neal Sondheimer
- Institute of Medical Science.,Departments of Paediatrics and Molecular Genetics, The University of Toronto, Toronto, ON, Canada.,Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, ON, Canada
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11
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Joshi PR, Baty K, Hopton S, Cordts I, Falkous G, Schoser B, Blakely EL, Taylor RW, Deschauer M. Progressive external ophthalmoplegia due to a recurrent de novo m.15990C>T MT-TP (mt-tRNA Pro) gene variant. Neuromuscul Disord 2020; 30:346-350. [PMID: 32305257 DOI: 10.1016/j.nmd.2020.02.020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Revised: 02/11/2020] [Accepted: 02/27/2020] [Indexed: 11/25/2022]
Abstract
Progressive external ophthalmoplegia is typically associated with single or multiple mtDNA deletions but occasionally mtDNA single nucleotide variants within mitochondrial transfer RNAs (mt-tRNAs) are identified. We report a 34-year-old female sporadic patient with progressive external ophthalmoplegia accompanied by exercise intolerance but neither fixed weakness nor multisystemic involvement. Histopathologically, abundant COX-deficient fibres were present in muscle with immunofluorescence analysis confirming the loss of mitochondrial complex I and IV proteins. Molecular genetic analysis identified a rare heteroplasmic m.15990C>T mt-tRNAPro variant reported previously in a single patient with childhood-onset myopathy. The variant in our patient was restricted to muscle. Single muscle fibre analysis identified higher heteroplasmy load in COX-deficient fibres than COX-normal fibres, confirming segregation of high heteroplasmic load with a biochemical defect. Our case highlights the phenotypic variability typically observed with pathogenic mt-tRNA mutations, whilst the identification of a second case with the m.15990C>T mutation not only confirms pathogenicity but shows that de novo mt-tRNA point mutations can arise in multiple, unrelated patients.
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Affiliation(s)
- Pushpa Raj Joshi
- Department of Neurology, Martin-Luther-University Halle-Wittenberg, Germany.
| | - Karen Baty
- Wellcome Centre for Mitochondrial Research, Newcastle University, Newcastle upon Tyne, United Kingdom; NHS Highly Specialised Mitochondrial Diagnostic Laboratory, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, United Kingdom
| | - Sila Hopton
- Wellcome Centre for Mitochondrial Research, Newcastle University, Newcastle upon Tyne, United Kingdom; NHS Highly Specialised Mitochondrial Diagnostic Laboratory, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, United Kingdom
| | - Isabell Cordts
- Department of Neurology, Technical University Munich, School of Medicine, Munich, Germany
| | - Gavin Falkous
- Wellcome Centre for Mitochondrial Research, Newcastle University, Newcastle upon Tyne, United Kingdom; NHS Highly Specialised Mitochondrial Diagnostic Laboratory, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, United Kingdom
| | - Benedikt Schoser
- Department of Neurology, Friedrich-Baur-Institute, University of Munich, Munich, Germany
| | - Emma L Blakely
- Wellcome Centre for Mitochondrial Research, Newcastle University, Newcastle upon Tyne, United Kingdom; NHS Highly Specialised Mitochondrial Diagnostic Laboratory, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, United Kingdom
| | - Robert W Taylor
- Wellcome Centre for Mitochondrial Research, Newcastle University, Newcastle upon Tyne, United Kingdom; NHS Highly Specialised Mitochondrial Diagnostic Laboratory, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, United Kingdom; Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Marcus Deschauer
- Department of Neurology, Technical University Munich, School of Medicine, Munich, Germany
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12
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Nissanka N, Moraes CT. Mitochondrial DNA heteroplasmy in disease and targeted nuclease-based therapeutic approaches. EMBO Rep 2020; 21:e49612. [PMID: 32073748 DOI: 10.15252/embr.201949612] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Revised: 12/11/2019] [Accepted: 01/29/2020] [Indexed: 12/31/2022] Open
Abstract
Mitochondrial DNA (mtDNA) encodes a subset of the genes which are responsible for oxidative phosphorylation. Pathogenic mutations in the human mtDNA are often heteroplasmic, where wild-type mtDNA species co-exist with the pathogenic mtDNA and a bioenergetic defect is only seen when the pathogenic mtDNA percentage surpasses a threshold for biochemical manifestations. mtDNA segregation during germline development can explain some of the extreme variation in heteroplasmy from one generation to the next. Patients with high heteroplasmy for deleterious mtDNA species will likely suffer from bona-fide mitochondrial diseases, which currently have no cure. Shifting mtDNA heteroplasmy toward the wild-type mtDNA species could provide a therapeutic option to patients. Mitochondrially targeted engineered nucleases, such as mitoTALENs and mitoZFNs, have been used in vitro in human cells harboring pathogenic patient-derived mtDNA mutations and more recently in vivo in a mouse model of a pathogenic mtDNA point mutation. These gene therapy tools for shifting mtDNA heteroplasmy can also be used in conjunction with other therapies aimed at eliminating and/or preventing the transfer of pathogenic mtDNA from mother to child.
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Affiliation(s)
- Nadee Nissanka
- Department of Neurology, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Carlos T Moraes
- Department of Neurology, University of Miami Miller School of Medicine, Miami, FL, USA
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13
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Li TR, Wang Q, Liu MM, Lv RJ. A Chinese Family With Adult-Onset Leigh-Like Syndrome Caused by the Heteroplasmic m.10191T>C Mutation in the Mitochondrial MTND3 Gene. Front Neurol 2019; 10:347. [PMID: 31105631 PMCID: PMC6499163 DOI: 10.3389/fneur.2019.00347] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Accepted: 03/21/2019] [Indexed: 12/21/2022] Open
Abstract
Leigh syndrome (LS) is a mitochondrial disease of infancy and early childhood, that is rarely seen in adults. The high degree of genetic and clinical heterogeneity makes LS a very complex syndrome. The clinical manifestations include neurological symptoms and various non-neurological symptoms, with different mutations differing in presentations and therapies. The m.10191T>C mutation in the mitochondrial DNA gene encoding in the respiratory chain complex I (CI) subunit of MTND3 results in the substitution of a highly conserved amino acid (p.Ser45Pro) within the ND3 protein, leading to CI dysfunction and causing a broad clinical spectrum of disorders that includes LS. Patients with the m.10191T>C mutation are rare in general, even more so in adults. In the present study, we report a family of patients with very rare adult-onset Leigh-like syndrome with the m.10191T>C mutation. The 24-year-old proband presented with seizures 6 years ago and developed refractory status epilepticus on admission. She had acute encephalopathy accompanied by lactic acidosis, symmetrical putamen and scattered cortical lesions. The video electroencephalogram suggested focal-onset seizures. She harbored the heteroplasmic m.10191T>C mutation in her blood and fibroblasts. Her aunt was diagnosed with mitochondrial disease at the age of 42, and had the heteroplasmic m.10191T>C mutation in her fibroblasts. Her aunt's son (cousin) died of respiratory failure at the age of 8, and we suspected he was also a case of LS. Furthermore, we reviewed the previously reported patients with the m.10191T>C mutation and summarized their characteristics. Recognizing the characteristics of these patients will help us improve the clinical understanding of LS or Leigh-like syndrome.
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Affiliation(s)
- Tao-Ran Li
- Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, China National Clinical Research Center for Neurological Diseases, Beijing, China.,Department of Neurology, XuanWu Hospital of Capital Medical University, Beijing, China
| | - Qun Wang
- Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, China National Clinical Research Center for Neurological Diseases, Beijing, China
| | - Mao-Mao Liu
- Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, China National Clinical Research Center for Neurological Diseases, Beijing, China
| | - Rui-Juan Lv
- Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, China National Clinical Research Center for Neurological Diseases, Beijing, China
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14
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Tolomeo D, Rubegni A, Severino M, Pochiero F, Bruno C, Cassandrini D, Madeo A, Doccini S, Pedemonte M, Rossi A, D'Amore F, Donati M, Di Rocco M, Santorelli F, Nesti C. Clinical and neuroimaging features of the m.10197G>A mtDNA mutation: New case reports and expansion of the phenotype variability. J Neurol Sci 2019; 399:69-75. [DOI: 10.1016/j.jns.2019.02.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2018] [Revised: 02/01/2019] [Accepted: 02/05/2019] [Indexed: 12/20/2022]
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15
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Mao X, Shi Y, Liang X, Cai M, Yang X, Chen S, Jia X, Wang J, Hu S, Lai S. Genetic diversities of MT-ND3 and MT-ND4L genes are associated with high-altitude adaptation. Mitochondrial DNA B Resour 2019. [DOI: 10.1080/23802359.2018.1544040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
Affiliation(s)
- Xudong Mao
- Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu, China
| | - Yu Shi
- Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu, China
| | - Xiaohu Liang
- Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu, China
| | - Mingcheng Cai
- Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu, China
| | - Xue Yang
- Chengdu Academy of Agriculture and Forestry Sciences, Chengdu, China
| | - Shiyi Chen
- Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu, China
| | - Xianbo Jia
- Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu, China
| | - Jie Wang
- Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu, China
| | - Shenqiang Hu
- Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu, China
| | - Songjia Lai
- Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu, China
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16
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Pereira C, Souza CFD, Vedolin L, Vairo F, Lorea C, Sobreira C, Nogueira C, Vilarinho L. Leigh Syndrome Due to mtDNA Pathogenic Variants. JOURNAL OF INBORN ERRORS OF METABOLISM AND SCREENING 2019. [DOI: 10.1590/2326-4594-jiems-2018-0003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Affiliation(s)
| | | | | | | | - Cláudia Lorea
- Department of Clinical Genomics, USA; Universidade Federal de Pelotas, Brazil
| | | | - Célia Nogueira
- Instituto Nacional de Saúde Doutor Ricardo Jorge, Portugal
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17
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Abstract
BACKGROUND Given the etiologic heterogeneity of disease classification using clinical phenomenology, we employed contemporary criteria to classify variants associated with myoclonic epilepsy with ragged-red fibers (MERRF) syndrome and to assess the strength of evidence of gene-disease associations. Standardized approaches are used to clarify the definition of MERRF, which is essential for patient diagnosis, patient classification, and clinical trial design. METHODS Systematic literature and database search with application of standardized assessment of gene-disease relationships using modified Smith criteria and of variants reported to be associated with MERRF using modified Yarham criteria. RESULTS Review of available evidence supports a gene-disease association for two MT-tRNAs and for POLG. Using modified Smith criteria, definitive evidence of a MERRF gene-disease association is identified for MT-TK. Strong gene-disease evidence is present for MT-TL1 and POLG. Functional assays that directly associate variants with oxidative phosphorylation impairment were critical to mtDNA variant classification. In silico analysis was of limited utility to the assessment of individual MT-tRNA variants. With the use of contemporary classification criteria, several mtDNA variants previously reported as pathogenic or possibly pathogenic are reclassified as neutral variants. CONCLUSIONS MERRF is primarily an MT-TK disease, with pathogenic variants in this gene accounting for ~90% of MERRF patients. Although MERRF is phenotypically and genotypically heterogeneous, myoclonic epilepsy is the clinical feature that distinguishes MERRF from other categories of mitochondrial disorders. Given its low frequency in mitochondrial disorders, myoclonic epilepsy is not explained simply by an impairment of cellular energetics. Although MERRF phenocopies can occur in other genes, additional data are needed to establish a MERRF disease-gene association. This approach to MERRF emphasizes standardized classification rather than clinical phenomenology, thus improving patient diagnosis and clinical trial design.
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18
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Nissanka N, Moraes CT. Mitochondrial DNA damage and reactive oxygen species in neurodegenerative disease. FEBS Lett 2018; 592:728-742. [PMID: 29281123 DOI: 10.1002/1873-3468.12956] [Citation(s) in RCA: 252] [Impact Index Per Article: 42.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2017] [Revised: 12/06/2017] [Accepted: 12/19/2017] [Indexed: 12/12/2022]
Abstract
Mitochondria are essential organelles within the cell where most ATP is produced through oxidative phosphorylation (OXPHOS). A subset of the genes needed for this process are encoded by the mitochondrial DNA (mtDNA). One consequence of OXPHOS is the production of mitochondrial reactive oxygen species (ROS), whose role in mediating cellular damage, particularly in damaging mtDNA during ageing, has been controversial. There are subsets of neurons that appear to be more sensitive to ROS-induced damage, and mitochondrial dysfunction has been associated with several neurodegenerative disorders. In this review, we will discuss the current knowledge in the field of mtDNA and neurodegeneration, the debate about ROS as a pathological or beneficial contributor to neuronal function, bona fide mtDNA diseases, and insights from mouse models of mtDNA defects affecting the central nervous system.
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Affiliation(s)
- Nadee Nissanka
- Neuroscience Graduate Program, University of Miami Miller School of Medicine, FL, USA
| | - Carlos T Moraes
- Neuroscience Graduate Program, University of Miami Miller School of Medicine, FL, USA.,Department of Neurology, University of Miami Miller School of Medicine, FL, USA
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19
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Mukai M, Nagata E. Mitochondrial Myopathy, Encephalopathy, Lactic Acidosis, and Stroke-like Episodes (MELAS) due to a m.10158T>C ND3 Mutation with a Normal Muscle Biopsy. Intern Med 2017; 56:2695. [PMID: 28883258 PMCID: PMC5658548 DOI: 10.2169/internalmedicine.8962-17] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Affiliation(s)
- Masako Mukai
- Department of Neurology, Tokai University School of Medicine, Japan
| | - Eiichiro Nagata
- Department of Neurology, Tokai University School of Medicine, Japan
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20
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Wojtala A, Karkucinska-Wieckowska A, Sardao VA, Szczepanowska J, Kowalski P, Pronicki M, Duszynski J, Wieckowski MR. Modulation of mitochondrial dysfunction-related oxidative stress in fibroblasts of patients with Leigh syndrome by inhibition of prooxidative p66Shc pathway. Mitochondrion 2017; 37:62-79. [PMID: 28739512 DOI: 10.1016/j.mito.2017.07.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2016] [Revised: 05/22/2017] [Accepted: 07/13/2017] [Indexed: 11/24/2022]
Abstract
The mitochondrial respiratory chain, and in particular, complex I, is a major source of reactive oxygen species (ROS) in cells. Elevated levels of ROS are associated with an imbalance between the rate of ROS formation and the capacity of the antioxidant defense system. Increased ROS production may lead to oxidation of DNA, lipids and proteins and thus can affect fundamental cellular processes. The aim of this study was to investigate the magnitude of intracellular oxidative stress in fibroblasts of patients with Leigh syndrome with defined mutations in complex I. Moreover, we hypothesized that activation of the p66Shc protein (phosphorylation of p66Shc at Ser36 by PKCβ), being part of the oxidative stress response pathway, is partially responsible for the increased ROS production in cells with dysfunctional complex I. Characterization of bioenergetic parameters and ROS production showed that the cellular model of Leigh syndrome is described by increased intracellular oxidative stress and oxidative damage to DNA and proteins, which correlate with increased p66Shc phosphorylation at Ser36. Treatment of patients' fibroblasts with hispidin (an inhibitor of the protein kinase PKCβ), in addition to decreasing ROS production and intracellular oxidative stress, resulted in restoration of complex I activity.
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Affiliation(s)
- Aleksandra Wojtala
- Department of Biochemistry, Nencki Institute of Experimental Biology, Warsaw, Poland
| | | | - Vilma A Sardao
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra, UC-Biotech Building, Biocant Park, Cantanhede, Portugal
| | - Joanna Szczepanowska
- Department of Biochemistry, Nencki Institute of Experimental Biology, Warsaw, Poland
| | - Pawel Kowalski
- Department of Medical Genetics, The Children's Memorial Health Institute, Warsaw, Poland
| | - Maciej Pronicki
- Department of Pathology, The Children's Memorial Health Institute, Warsaw, Poland
| | - Jerzy Duszynski
- Department of Biochemistry, Nencki Institute of Experimental Biology, Warsaw, Poland
| | - Mariusz R Wieckowski
- Department of Biochemistry, Nencki Institute of Experimental Biology, Warsaw, Poland.
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21
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Galkin A, Moncada S. Modulation of the conformational state of mitochondrial complex I as a target for therapeutic intervention. Interface Focus 2017; 7:20160104. [PMID: 28382200 DOI: 10.1098/rsfs.2016.0104] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
In recent years, there have been significant advances in our understanding of the functions of mitochondrial complex I other than the generation of energy. These include its role in generation of reactive oxygen species, involvement in the hypoxic tissue response and its possible regulation by nitric oxide (NO) metabolites. In this review, we will focus on the hypoxic conformational change of this mitochondrial enzyme, the so-called active/deactive transition. This conformational change is physiological and relevant to the understanding of certain pathological conditions including, in the cardiovascular system, ischaemia/reperfusion (I/R) damage. We will discuss how complex I can be affected by NO metabolites and will outline some potential mitochondria-targeted therapies in I/R damage.
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Affiliation(s)
- Alexander Galkin
- Feil Family Brain and Mind Research Institute, Weill Cornell Medical College, 401 East 61st Street, 5th floor, New York, NY 10065, USA; Queens University Belfast, School of Biological Sciences, Medical Biology Centre, 97 Lisburn Road, Belfast BT9 7BL, UK
| | - Salvador Moncada
- Manchester Cancer Research Centre , University of Manchester , Wilmslow Road, Manchester M20 4QL , UK
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22
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Sallevelt SCEH, de Die-Smulders CEM, Hendrickx ATM, Hellebrekers DMEI, de Coo IFM, Alston CL, Knowles C, Taylor RW, McFarland R, Smeets HJM. De novo mtDNA point mutations are common and have a low recurrence risk. J Med Genet 2016; 54:73-83. [PMID: 27450679 PMCID: PMC5502310 DOI: 10.1136/jmedgenet-2016-103876] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Revised: 06/02/2016] [Accepted: 06/09/2016] [Indexed: 12/25/2022]
Abstract
Background Severe, disease-causing germline mitochondrial (mt)DNA mutations are maternally inherited or arise de novo. Strategies to prevent transmission are generally available, but depend on recurrence risks, ranging from high/unpredictable for many familial mtDNA point mutations to very low for sporadic, large-scale single mtDNA deletions. Comprehensive data are lacking for de novo mtDNA point mutations, often leading to misconceptions and incorrect counselling regarding recurrence risk and reproductive options. We aim to study the relevance and recurrence risk of apparently de novo mtDNA point mutations. Methods Systematic study of prenatal diagnosis (PND) and recurrence of mtDNA point mutations in families with de novo cases, including new and published data. ‘De novo’ based on the absence of the mutation in multiple (postmitotic) maternal tissues is preferred, but mutations absent in maternal blood only were also included. Results In our series of 105 index patients (33 children and 72 adults) with (likely) pathogenic mtDNA point mutations, the de novo frequency was 24.6%, the majority being paediatric. PND was performed in subsequent pregnancies of mothers of four de novo cases. A fifth mother opted for preimplantation genetic diagnosis because of a coexisting Mendelian genetic disorder. The mtDNA mutation was absent in all four prenatal samples and all 11 oocytes/embryos tested. A literature survey revealed 137 de novo cases, but PND was only performed for 9 (including 1 unpublished) mothers. In one, recurrence occurred in two subsequent pregnancies, presumably due to germline mosaicism. Conclusions De novo mtDNA point mutations are a common cause of mtDNA disease. Recurrence risk is low. This is relevant for genetic counselling, particularly for reproductive options. PND can be offered for reassurance.
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Affiliation(s)
- Suzanne C E H Sallevelt
- Department of Clinical Genetics, Maastricht University Medical Centre (MUMC), Maastricht, The Netherlands
| | - Christine E M de Die-Smulders
- Department of Clinical Genetics, Maastricht University Medical Centre (MUMC), Maastricht, The Netherlands.,Research School for Developmental Biology (GROW), Maastricht University, Maastricht, The Netherlands
| | - Alexandra T M Hendrickx
- Department of Clinical Genetics, Maastricht University Medical Centre (MUMC), Maastricht, The Netherlands
| | - Debby M E I Hellebrekers
- Department of Clinical Genetics, Maastricht University Medical Centre (MUMC), Maastricht, The Netherlands
| | - Irenaeus F M de Coo
- Department of Neurology, Erasmus MC-Sophia Children's Hospital Rotterdam, Rotterdam, The Netherlands
| | - Charlotte L Alston
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Newcastle upon Tyne, UK
| | - Charlotte Knowles
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Newcastle upon Tyne, UK
| | - Robert W Taylor
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Newcastle upon Tyne, UK
| | - Robert McFarland
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Newcastle upon Tyne, UK
| | - Hubert J M Smeets
- Department of Clinical Genetics, Maastricht University Medical Centre (MUMC), Maastricht, The Netherlands.,Research School for Developmental Biology (GROW), Maastricht University, Maastricht, The Netherlands.,Research School for Cardiovascular Diseases in Maastricht, CARIM, Maastricht University, Maastricht, The Netherlands
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23
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Dröse S, Stepanova A, Galkin A. Ischemic A/D transition of mitochondrial complex I and its role in ROS generation. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2016; 1857:946-57. [PMID: 26777588 PMCID: PMC4893024 DOI: 10.1016/j.bbabio.2015.12.013] [Citation(s) in RCA: 94] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Revised: 12/11/2015] [Accepted: 12/25/2015] [Indexed: 12/12/2022]
Abstract
Mitochondrial complex I (NADH:ubiquinone oxidoreductase) is a key enzyme in cellular energy metabolism and provides approximately 40% of the proton-motive force that is utilized during mitochondrial ATP production. The dysregulation of complex I function – either genetically, pharmacologically, or metabolically induced – has severe pathophysiological consequences that often involve an imbalance in the production of reactive oxygen species (ROS). Slow transition of the active (A) enzyme to the deactive, dormant (D) form takes place during ischemia in metabolically active organs such as the heart and brain. The reactivation of complex I occurs upon reoxygenation of ischemic tissue, a process that is usually accompanied by an increase in cellular ROS production. Complex I in the D-form serves as a protective mechanism preventing the oxidative burst upon reperfusion. Conversely, however, the D-form is more vulnerable to oxidative/nitrosative damage. Understanding the so-called active/deactive (A/D) transition may contribute to the development of new therapeutic interventions for conditions like stroke, cardiac infarction, and other ischemia-associated pathologies. In this review, we summarize current knowledge on the mechanism of A/D transition of mitochondrial complex I considering recently available structural data and site-specific labeling experiments. In addition, this review discusses in detail the impact of the A/D transition on ROS production by complex I and the S-nitrosation of a critical cysteine residue of subunit ND3 as a strategy to prevent oxidative damage and tissue damage during ischemia–reperfusion injury. This article is part of a Special Issue entitled Respiratory complex I, edited by Volker Zickermann and Ulrich Brandt. The current knowledge on active/deactive (A/D) transition of complex I is reviewed. The mechanism and driving force of the A/D conformational change are discussed. The A/D transition can affect ROS production and ischemia/reperfusion injury.
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Affiliation(s)
- Stefan Dröse
- Clinic of Anesthesiology, Intensive-Care Medicine and Pain Therapy, University Hospital Frankfurt, Frankfurt am Main 60590, Germany.
| | - Anna Stepanova
- Medical Biology Centre, School of Biological Sciences, Queens University Belfast, 97 Lisburn Road, Belfast BT9 7BL, UK
| | - Alexander Galkin
- Medical Biology Centre, School of Biological Sciences, Queens University Belfast, 97 Lisburn Road, Belfast BT9 7BL, UK; Feil Family Brain and Mind Research Institute, Weill Cornell Medical College, 407 East 61st Street, New York, NY 10065, USA.
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24
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Ng YS, Turnbull DM. Mitochondrial disease: genetics and management. J Neurol 2016; 263:179-91. [PMID: 26315846 PMCID: PMC4723631 DOI: 10.1007/s00415-015-7884-3] [Citation(s) in RCA: 78] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Revised: 08/18/2015] [Accepted: 08/18/2015] [Indexed: 12/14/2022]
Abstract
Mitochondrial disease is one of the most common groups of genetic diseases with a minimum prevalence of greater than 1 in 5000 in adults. Whilst multi-system involvement is often evident, neurological manifestation is the principal presentation in most cases. The multiple clinical phenotypes and the involvement of both the mitochondrial and nuclear genome make mitochondrial disease particularly challenging for the clinician. In this review article we cover mitochondrial genetics and common neurological presentations associated with adult mitochondrial disease. In addition, specific and supportive treatments are discussed.
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Affiliation(s)
- Yi Shiau Ng
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK
| | - Doug M Turnbull
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK.
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25
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Jin T, Shen H, Zhao Z, Hu J. Clinical, pathological, and neuroimaging analyses of two cases of Leigh syndrome in a Chinese family. J Child Neurol 2014; 29:NP143-8. [PMID: 24413359 DOI: 10.1177/0883073813512524] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
In this study, the authors examined the clinical manifestations, skeletal muscle pathological characteristics, and neuroimaging results of 2 cases of Leigh syndrome in a Chinese family. The 2 patients presented with general weakness, and 1 of them presented with an impairment of vision. Skeletal muscle biopsies showed a deficiency in cytochrome c oxidase levels. Brain magnetic resonance imaging showed increased T1 and T2 signal intensities in the centrum ovale and dentate nucleus. Diffusion-weighted imaging showed a high-intensity signal. Magnetic resonance spectroscopy showed elevated levels of lactic acid in lesions. The examination of 1 patient at disease onset and during disease remission showed that the lesions detected by magnetic resonance imaging and diffusion-weighted imaging, and the peak for lactic acid detected by magnetic resonance spectroscopy, decreased during remission. These data suggest that changes in the imaging results of patients with Leigh syndrome correlate with disease course and pathogenetic condition.
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Affiliation(s)
- Taoran Jin
- Departments of Cadre Ward, Third Hospital of Hebei Medical University, Shijiazhuang, China
| | - Hongrui Shen
- Departments of Neuromuscular Disease, Key Laboratory of Orthopedic Biomechanics of Hebei Province, Third Hospital of Hebei Medical University, Shijiazhuang, China
| | - Zhe Zhao
- Departments of Neuromuscular Disease, Key Laboratory of Orthopedic Biomechanics of Hebei Province, Third Hospital of Hebei Medical University, Shijiazhuang, China
| | - Jing Hu
- Departments of Neuromuscular Disease, Key Laboratory of Orthopedic Biomechanics of Hebei Province, Third Hospital of Hebei Medical University, Shijiazhuang, China
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Levy RJ, Ríos PG, Akman HO, Sciacco M, De Vivo DC, DiMauro S. Long survival in patients with leigh syndrome and the m.10191T>C mutation in MT-ND3 : a case report and review of the literature. J Child Neurol 2014; 29:NP105-10. [PMID: 24284231 PMCID: PMC4035473 DOI: 10.1177/0883073813506783] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
We report an unusual case of Leigh syndrome due to the m.10191T>C mutation in the complex I gene MT-ND3. This mutation has been associated with a spectrum of clinical phenotypes ranging from infant lethality to adult onset. Despite infantile onset and severe symptoms, our patient has survived to early adulthood because of a strict dietary regimen and parental care. This patient is an extreme example of the frequently prolonged course of Leigh syndrome due to this particular mutation.
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Affiliation(s)
- Rebecca J. Levy
- Department of Neurology, Columbia University Medical Center, New York, NY, USA
| | | | - Hasan O. Akman
- Department of Neurology, Columbia University Medical Center, New York, NY, USA
| | - Monica Sciacco
- Neuromuscular Unit, IRCCS Foundation Ca’ Granda Ospedale Maggiore Policlinico, Dino Ferrari Centre, University of Milan, 20122 Milan, Italy
| | - Darryl C. De Vivo
- Department of Neurology, Columbia University Medical Center, New York, NY, USA
| | - Salvatore DiMauro
- Department of Neurology, Columbia University Medical Center, New York, NY, USA
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Miller DK, Menezes MJ, Simons C, Riley LG, Cooper ST, Grimmond SM, Thorburn DR, Christodoulou J, Taft RJ. Rapid identification of a novel complex I MT-ND3 m.10134C>A mutation in a Leigh syndrome patient. PLoS One 2014; 9:e104879. [PMID: 25118196 PMCID: PMC4130626 DOI: 10.1371/journal.pone.0104879] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2014] [Accepted: 07/17/2014] [Indexed: 11/19/2022] Open
Abstract
Leigh syndrome (LS) is a rare progressive multi-system neurodegenerative disorder, the genetics of which is frequently difficult to resolve. Rapid determination of the genetic etiology of LS in a 5-year-old girl facilitated inclusion in Edison Pharmaceutical's phase 2B clinical trial of EPI-743. SNP-arrays and high-coverage whole exome sequencing were performed on the proband, both parents and three unaffected siblings. Subsequent multi-tissue targeted high-depth mitochondrial sequencing was performed using custom long-range PCR amplicons. Tissue-specific mutant load was also assessed by qPCR. Complex I was interrogated by spectrophotometric enzyme assays and Western Blot. No putatively causal mutations were identified in nuclear-encoded genes. Analysis of low-coverage off-target mitochondrial reads revealed a previously unreported mitochondrial mutation in the proband in MT-ND3 (m.10134C>A, p.Q26K), a Complex I mitochondrial gene previously associated with LS. Targeted investigations demonstrated that this mutation was 1% heteroplasmic in the mother's blood and homoplasmic in the proband's blood, fibroblasts, liver and muscle. Enzyme assays revealed decreased Complex I activity. The identification of this novel LS MT-ND3 variant, the genomics of which was accomplished in less than 3.5 weeks, indicates that rapid genomic approaches may prove useful in time-sensitive cases with an unresolved genetic diagnosis.
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Affiliation(s)
- David K. Miller
- Queensland Centre for Medical Genomics, Institute for Molecular Bioscience, University of Queensland, St Lucia, Queensland, Australia
| | - Minal J. Menezes
- Genetic Metabolic Disorders Research Unit, Kids Research Institute, Children’s Hospital at Westmead, Sydney, Westmead New South Wales, Australia
- Discipline of Paediatrics and Child Health, Sydney Medical School, University of Sydney, Camperdown New South Wales, Australia
| | - Cas Simons
- Institute for Molecular Bioscience, University of Queensland, St Lucia, Queensland, Australia
| | - Lisa G. Riley
- Genetic Metabolic Disorders Research Unit, Kids Research Institute, Children’s Hospital at Westmead, Sydney, Westmead New South Wales, Australia
| | - Sandra T. Cooper
- Discipline of Paediatrics and Child Health, Sydney Medical School, University of Sydney, Camperdown New South Wales, Australia
- Institute for Neuroscience and Muscle Research, Children’s Hospital at Westmead, Sydney, New South Wales, Australia
| | - Sean M. Grimmond
- Queensland Centre for Medical Genomics, Institute for Molecular Bioscience, University of Queensland, St Lucia, Queensland, Australia
| | - David R. Thorburn
- Murdoch Childrens Research Institute and Victorian Clinical Genetics Services, Royal Children’s Hospital, Flemington Road, Parkville, Melbourne, Victoria, Australia
- Department of Paediatrics, University of Melbourne, Melbourne, Victoria, Australia
| | - John Christodoulou
- Genetic Metabolic Disorders Research Unit, Kids Research Institute, Children’s Hospital at Westmead, Sydney, Westmead New South Wales, Australia
- Discipline of Paediatrics and Child Health, Sydney Medical School, University of Sydney, Camperdown New South Wales, Australia
- Discipline of Genetic Medicine, Sydney Medical School, University of Sydney, Camperdown, New South Wales, Australia
| | - Ryan J. Taft
- Institute for Molecular Bioscience, University of Queensland, St Lucia, Queensland, Australia
- Departments of Integrative Systems Biology and Pediatrics, George Washington University School of Medicine, Washington, D.C., United States of America
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Leng Y, Liu Y, Fang X, Li Y, Yu L, Yuan Y, Wang Z. The mitochondrial DNA 10197 G > A mutation causes MELAS/Leigh overlap syndrome presenting with acute auditory agnosia. ACTA ACUST UNITED AC 2014; 26:208-12. [PMID: 24708134 DOI: 10.3109/19401736.2014.905860] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes/Leigh (MELAS/LS) overlap syndrome is a mitochondrial disorder subtype with clinical and magnetic resonance imaging (MRI) features that are characteristic of both MELAS and Leigh syndrome (LS). Here, we report an MELAS/LS case presenting with cortical deafness and seizures. Cranial MRI revealed multiple lesions involving bilateral temporal lobes, the basal ganglia and the brainstem, which conformed to neuroimaging features of both MELAS and LS. Whole mitochondrial DNA (mtDNA) sequencing and PCR-RFLP revealed a de novo heteroplasmic m.10197 G > A mutation in the NADH dehydrogenase subunit 3 gene (ND3), which was predicted to cause an alanine to threonine substitution at amino acid 47. Although the mtDNA m.10197 G > A mutation has been reported in association with LS, Leber hereditary optic neuropathy and dystonia, it has never been linked with MELAS/LS overlap syndrome. Our patient therefore expands the phenotypic spectrum of the mtDNA m.10197 G > A mutation.
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Affiliation(s)
- Yinglin Leng
- Department of Neurology, Peking University First Hospital , Beijing , China
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29
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Molecular mechanism and physiological role of active-deactive transition of mitochondrial complex I. Biochem Soc Trans 2014; 41:1325-30. [PMID: 24059527 PMCID: PMC3990385 DOI: 10.1042/bst20130088] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The unique feature of mitochondrial complex I is the so-called A/D transition (active–deactive transition). The A-form catalyses rapid oxidation of NADH by ubiquinone (k ~104 min−1) and spontaneously converts into the D-form if the enzyme is idle at physiological temperatures. Such deactivation occurs in vitro in the absence of substrates or in vivo during ischaemia, when the ubiquinone pool is reduced. The D-form can undergo reactivation given both NADH and ubiquinone availability during slow (k ~1–10 min−1) catalytic turnover(s). We examined known conformational differences between the two forms and suggested a mechanism exerting A/D transition of the enzyme. In addition, we discuss the physiological role of maintaining the enzyme in the D-form during the ischaemic period. Accumulation of the D-form of the enzyme would prevent reverse electron transfer from ubiquinol to FMN which could lead to superoxide anion generation. Deactivation would also decrease the initial burst of respiration after oxygen reintroduction. Therefore the A/D transition could be an intrinsic protective mechanism for lessening oxidative damage during the early phase of reoxygenation. Exposure of Cys39 of mitochondrially encoded subunit ND3 makes the D-form susceptible for modification by reactive oxygen species and nitric oxide metabolites which arrests the reactivation of the D-form and inhibits the enzyme. The nature of thiol modification defines deactivation reversibility, the reactivation timescale, the status of mitochondrial bioenergetics and therefore the degree of recovery of the ischaemic tissues after reoxygenation.
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30
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Babot M, Birch A, Labarbuta P, Galkin A. Characterisation of the active/de-active transition of mitochondrial complex I. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2014; 1837:1083-92. [PMID: 24569053 PMCID: PMC4331042 DOI: 10.1016/j.bbabio.2014.02.018] [Citation(s) in RCA: 98] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/30/2013] [Revised: 02/14/2014] [Accepted: 02/17/2014] [Indexed: 12/12/2022]
Abstract
Oxidation of NADH in the mitochondrial matrix of aerobic cells is catalysed by mitochondrial complex I. The regulation of this mitochondrial enzyme is not completely understood. An interesting characteristic of complex I from some organisms is the ability to adopt two distinct states: the so-called catalytically active (A) and the de-active, dormant state (D). The A-form in situ can undergo de-activation when the activity of the respiratory chain is limited (i.e. in the absence of oxygen). The mechanisms and driving force behind the A/D transition of the enzyme are currently unknown, but several subunits are most likely involved in the conformational rearrangements: the accessory subunit 39 kDa (NDUFA9) and the mitochondrially encoded subunits, ND3 and ND1. These three subunits are located in the region of the quinone binding site. The A/D transition could represent an intrinsic mechanism which provides a fast response of the mitochondrial respiratory chain to oxygen deprivation. The physiological role of the accumulation of the D-form in anoxia is most probably to protect mitochondria from ROS generation due to the rapid burst of respiration following reoxygenation. The de-activation rate varies in different tissues and can be modulated by the temperature, the presence of free fatty acids and divalent cations, the NAD+/NADH ratio in the matrix, the presence of nitric oxide and oxygen availability. Cysteine-39 of the ND3 subunit, exposed in the D-form, is susceptible to covalent modification by nitrosothiols, ROS and RNS. The D-form in situ could react with natural effectors in mitochondria or with pharmacological agents. Therefore the modulation of the re-activation rate of complex I could be a way to ameliorate the ischaemia/reperfusion damage. This article is part of a Special Issue entitled: 18th European Bioenergetic Conference. Guest Editors: Manuela Pereira and Miguel Teixeira. The potential mechanism of complex I A/D transition is discussed. An —SH group exposed in the D-form is susceptible to covalent modification. The role of A/D transition in tissue response to ischaemia is proposed.
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Affiliation(s)
- Marion Babot
- Queen's University Belfast, School of Biological Sciences, Medical Biology Centre, 97 Lisburn Road, Belfast BT9 7BL, UK
| | - Amanda Birch
- Queen's University Belfast, School of Biological Sciences, Medical Biology Centre, 97 Lisburn Road, Belfast BT9 7BL, UK
| | - Paola Labarbuta
- Queen's University Belfast, School of Biological Sciences, Medical Biology Centre, 97 Lisburn Road, Belfast BT9 7BL, UK
| | - Alexander Galkin
- Queen's University Belfast, School of Biological Sciences, Medical Biology Centre, 97 Lisburn Road, Belfast BT9 7BL, UK.
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31
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Tang S, Wang J, Zhang VW, Li FY, Landsverk M, Cui H, Truong CK, Wang G, Chen LC, Graham B, Scaglia F, Schmitt ES, Craigen WJ, Wong LJC. Transition to next generation analysis of the whole mitochondrial genome: a summary of molecular defects. Hum Mutat 2013; 34:882-93. [PMID: 23463613 DOI: 10.1002/humu.22307] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2012] [Accepted: 02/15/2013] [Indexed: 01/06/2023]
Abstract
The diagnosis of mitochondrial disorders is challenging because of the clinical variability and genetic heterogeneity. Conventional analysis of the mitochondrial genome often starts with a screening panel for common mitochondrial DNA (mtDNA) point mutations and large deletions (mtScreen). If negative, it has been traditionally followed by Sanger sequencing of the entire mitochondrial genome (mtWGS). The recently developed "Next-Generation Sequencing" (NGS) technology offers a robust high-throughput platform for comprehensive mtDNA analysis. Here, we summarize the results of the past 6 years of clinical practice using the mtScreen and mtWGS tests on 9,261 and 2,851 unrelated patients, respectively. A total of 344 patients (3.7%) had mutations identified by mtScreen and 99 (3.5%) had mtDNA mutations identified by mtWGS. The combinatorial analyses of mtDNA and POLG revealed a diagnostic yield of 6.7% in patients with suspected mitochondrial disorders but no recognizable syndromes. From the initial mtWGS-NGS cohort of 391 patients, 21 mutation-positive cases (5.4%) have been identified. The mtWGS-NGS provides a one-step approach to detect common and uncommon point mutations, as well as deletions. Additionally, NGS provides accurate, sensitive heteroplasmy measurement, and the ability to map deletion breakpoints. A new era of more efficient molecular diagnosis of mtDNA mutations has arrived.
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Affiliation(s)
- Sha Tang
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030, USA
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