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Thind S, Lima D, Booy E, Trinh D, McKenna SA, Kuss S. Cytochrome c oxidase deficiency detection in human fibroblasts using scanning electrochemical microscopy. Proc Natl Acad Sci U S A 2024; 121:e2310288120. [PMID: 38154062 PMCID: PMC10769844 DOI: 10.1073/pnas.2310288120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Accepted: 11/17/2023] [Indexed: 12/30/2023] Open
Abstract
Cytochrome c oxidase deficiency (COXD) is an inherited disorder characterized by the absence or mutation in the genes encoding for the cytochrome c oxidase protein (COX). COX deficiency results in severe muscle weakness, heart, liver, and kidney disorders, as well as brain damage in infants and adolescents, leading to death in many cases. With no cure for this disorder, finding an efficient, inexpensive, and early means of diagnosis is essential to minimize symptoms and long-term disabilities. Furthermore, muscle biopsy, the traditional detection method, is invasive, expensive, and time-consuming. This study demonstrates the applicability of scanning electrochemical microscopy to quantify COX activity in living human fibroblast cells. Taking advantage of the interaction between the redox mediator N, N, N', N'-tetramethyl-para-phenylene-diamine, and COX, the enzymatic activity was successfully quantified by monitoring current changes using a platinum microelectrode and determining the apparent heterogeneous rate constant k0 using numerical modeling. This study provides a foundation for developing a diagnostic method for detecting COXD in infants, which has the potential to increase treatment effectiveness and improve the quality of life of affected individuals.
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Affiliation(s)
- Shubhneet Thind
- Laboratory for Bioanalytics and Electrochemical Sensing, Department of Chemistry, University of Manitoba, Winnipeg, MBR3T 2N2, Canada
| | - Dhésmon Lima
- Laboratory for Bioanalytics and Electrochemical Sensing, Department of Chemistry, University of Manitoba, Winnipeg, MBR3T 2N2, Canada
| | - Evan Booy
- Department of Chemistry, University of Manitoba, Winnipeg, MBR3T 2N2, Canada
| | - Dao Trinh
- Laboratoire des Sciences de l’Ingénieur Pour l’Environnement, UMR CNRS 7356, Université de La Rochelle, Pôle Sciences et Technologie17042, La Rochelle, Cedex 1, France
| | - Sean A. McKenna
- Department of Chemistry, University of Manitoba, Winnipeg, MBR3T 2N2, Canada
| | - Sabine Kuss
- Laboratory for Bioanalytics and Electrochemical Sensing, Department of Chemistry, University of Manitoba, Winnipeg, MBR3T 2N2, Canada
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Ronchi D, Garbellini M, Magri F, Menni F, Meneri M, Bedeschi MF, Dilena R, Cecchetti V, Picciolli I, Furlan F, Polimeni V, Salani S, Pezzoli L, Fortunato F, Bellini M, Piga D, Ripolone M, Zanotti S, Napoli L, Ciscato P, Sciacco M, Mangili G, Mosca F, Corti S, Iascone M, Comi GP. A biallelic variant in COX18 cause isolated Complex IV deficiency associated with neonatal encephalo-cardio-myopathy and axonal sensory neuropathy. Eur J Hum Genet 2023; 31:1414-1420. [PMID: 37468577 PMCID: PMC10689781 DOI: 10.1038/s41431-023-01433-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Revised: 07/03/2023] [Accepted: 07/10/2023] [Indexed: 07/21/2023] Open
Abstract
Pathogenic variants impacting upon assembly of mitochondrial respiratory chain Complex IV (Cytochrome c Oxidase or COX) predominantly result in early onset mitochondrial disorders often leading to CNS, skeletal and cardiac muscle manifestations. The aim of this study is to describe a molecular defect in the COX assembly factor gene COX18 as the likely cause of a neonatal form of mitochondrial encephalo-cardio-myopathy and axonal sensory neuropathy. The proband is a 19-months old female displaying hypertrophic cardiomyopathy at birth and myopathy with axonal sensory neuropathy and failure to thrive developing in the first months of life. Serum lactate was consistently increased. Whole exome sequencing allowed the prioritization of the unreported homozygous substitution NM_001297732.2:c.667 G > C p.(Asp223His) in COX18. Patient's muscle biopsy revealed severe and diffuse COX deficiency and striking mitochondrial abnormalities. Biochemical and enzymatic studies in patient's myoblasts and in HEK293 cells after COX18 silencing showed a severe impairment of both COX activity and assembly. The biochemical defect was partially rescued by delivery of wild-type COX18 cDNA into patient's myoblasts. Our study identifies a novel defect of COX assembly and expands the number of nuclear genes involved in a mitochondrial disorder due to isolated COX deficiency.
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Affiliation(s)
- Dario Ronchi
- Dino Ferrari Center, Department of Pathophysiology and Transplantation, University of Milan, Milan, Italy
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Neurology Unit, Milan, Italy
| | - Manuela Garbellini
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Neurology Unit, Milan, Italy
| | - Francesca Magri
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Neurology Unit, Milan, Italy
| | - Francesca Menni
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Regional Clinical Center for expanded newborn screening, Milan, Italy
| | - Megi Meneri
- Dino Ferrari Center, Department of Pathophysiology and Transplantation, University of Milan, Milan, Italy
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Neurology Unit, Milan, Italy
| | | | - Robertino Dilena
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, UO Neurofisiopatologia, Milan, Italy
| | - Valeria Cecchetti
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Neonatal Intensive Care Unit, Milan, Italy
| | - Irene Picciolli
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Neonatal Intensive Care Unit, Milan, Italy
| | - Francesca Furlan
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Regional Clinical Center for expanded newborn screening, Milan, Italy
| | - Valentina Polimeni
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Neonatal Intensive Care Unit, Milan, Italy
| | - Sabrina Salani
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Neurology Unit, Milan, Italy
| | - Laura Pezzoli
- ASST Papa Giovanni XXIII, Laboratorio di Genetica Medica, Bergamo, Italy
| | - Francesco Fortunato
- Dino Ferrari Center, Department of Pathophysiology and Transplantation, University of Milan, Milan, Italy
| | - Matteo Bellini
- ASST Papa Giovanni XXIII, Laboratorio di Genetica Medica, Bergamo, Italy
| | - Daniela Piga
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Neurology Unit, Milan, Italy
| | - Michela Ripolone
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Neuromuscular and Rare Disease Unit, Milan, Italy
| | - Simona Zanotti
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Neuromuscular and Rare Disease Unit, Milan, Italy
| | - Laura Napoli
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Neuromuscular and Rare Disease Unit, Milan, Italy
| | - Patrizia Ciscato
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Neuromuscular and Rare Disease Unit, Milan, Italy
| | - Monica Sciacco
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Neuromuscular and Rare Disease Unit, Milan, Italy
| | | | - Fabio Mosca
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Neonatal Intensive Care Unit, Milan, Italy
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
| | - Stefania Corti
- Dino Ferrari Center, Department of Pathophysiology and Transplantation, University of Milan, Milan, Italy
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Neuromuscular and Rare Disease Unit, Milan, Italy
| | - Maria Iascone
- ASST Papa Giovanni XXIII, Laboratorio di Genetica Medica, Bergamo, Italy
| | - Giacomo Pietro Comi
- Dino Ferrari Center, Department of Pathophysiology and Transplantation, University of Milan, Milan, Italy.
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Neurology Unit, Milan, Italy.
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3
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Li W, Dai Y, Shi B, Yue F, Zou J, Xu G, Jiang X, Wang F, Zhou X, Liu L. LRPPRC sustains Yap-P27-mediated cell ploidy and P62-HDAC6-mediated autophagy maturation and suppresses genome instability and hepatocellular carcinomas. Oncogene 2020; 39:3879-3892. [PMID: 32203162 DOI: 10.1038/s41388-020-1257-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Revised: 02/28/2020] [Accepted: 03/03/2020] [Indexed: 12/25/2022]
Abstract
Mutants in the gene encoding mitochondrion-associated protein LRPPRC were found to be associated with French Canadian Type Leigh syndrome, a human disorder characterized with neurodegeneration and cytochrome c oxidase deficiency. LRPPRC interacts with one of microtubule-associated protein family MAP1S that promotes autophagy initiation and maturation to suppress genomic instability and tumorigenesis. Previously, although various studies have attributed LRPPRC nuclear acid-associated functions, we characterized that LRPPRC acted as an inhibitor of autophagy in human cancer cells. Here we show that liver-specific deletion of LRPPRC causes liver-specific increases of YAP and P27 and decreases of P62, leading to an increase of cell polyploidy and an impairment of autophagy maturation. The blockade of autophagy maturation and promotion of polyploidy caused by LRPPRC depletion synergistically enhances diethylnitrosamine-induced DNA damage, genome instability, and further tumorigenesis so that LRPPRC knockout mice develop more and larger hepatocellular carcinomas and survive a shorter lifespan. Therefore, LRPPRC suppresses genome instability and hepatocellular carcinomas and promotes survivals in mice by sustaining Yap-P27-mediated cell ploidy and P62-HDAC6-controlled autophagy maturation.
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Affiliation(s)
- Wenjiao Li
- The Fifth Affiliated Hospital of Guangzhou Medical University, 621 Gangwan Rd, Huangpu District, Guangzhou, 710700, Guangdong, PR China
- Institute of Biosciences and Technology, Texas A&M University, 2121 W. Holcombe Blvd., Houston, TX, 77030, USA
| | - Yuan Dai
- Institute of Biosciences and Technology, Texas A&M University, 2121 W. Holcombe Blvd., Houston, TX, 77030, USA
| | - Boyun Shi
- The Fifth Affiliated Hospital of Guangzhou Medical University, 621 Gangwan Rd, Huangpu District, Guangzhou, 710700, Guangdong, PR China
- Institute of Biosciences and Technology, Texas A&M University, 2121 W. Holcombe Blvd., Houston, TX, 77030, USA
| | - Fei Yue
- Institute of Biosciences and Technology, Texas A&M University, 2121 W. Holcombe Blvd., Houston, TX, 77030, USA
| | - Jing Zou
- Institute of Biosciences and Technology, Texas A&M University, 2121 W. Holcombe Blvd., Houston, TX, 77030, USA
| | - Guibin Xu
- The Fifth Affiliated Hospital of Guangzhou Medical University, 621 Gangwan Rd, Huangpu District, Guangzhou, 710700, Guangdong, PR China
- Institute of Biosciences and Technology, Texas A&M University, 2121 W. Holcombe Blvd., Houston, TX, 77030, USA
| | - Xianhan Jiang
- The Fifth Affiliated Hospital of Guangzhou Medical University, 621 Gangwan Rd, Huangpu District, Guangzhou, 710700, Guangdong, PR China
- Institute of Biosciences and Technology, Texas A&M University, 2121 W. Holcombe Blvd., Houston, TX, 77030, USA
| | - Fen Wang
- Institute of Biosciences and Technology, Texas A&M University, 2121 W. Holcombe Blvd., Houston, TX, 77030, USA
| | - Xinke Zhou
- The Fifth Affiliated Hospital of Guangzhou Medical University, 621 Gangwan Rd, Huangpu District, Guangzhou, 710700, Guangdong, PR China
| | - Leyuan Liu
- The Fifth Affiliated Hospital of Guangzhou Medical University, 621 Gangwan Rd, Huangpu District, Guangzhou, 710700, Guangdong, PR China.
- Institute of Biosciences and Technology, Texas A&M University, 2121 W. Holcombe Blvd., Houston, TX, 77030, USA.
- Department of Molecular and Cellular Medicine, College of Medicine, Texas A&M University, College Station, TX, USA.
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4
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Ferreira N, Andoniou CE, Perks KL, Ermer JA, Rudler DL, Rossetti G, Periyakaruppiah A, Wong JKY, Rackham O, Noakes PG, Degli-Esposti MA, Filipovska A. Murine cytomegalovirus infection exacerbates complex IV deficiency in a model of mitochondrial disease. PLoS Genet 2020; 16:e1008604. [PMID: 32130224 PMCID: PMC7055822 DOI: 10.1371/journal.pgen.1008604] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Accepted: 01/10/2020] [Indexed: 11/30/2022] Open
Abstract
The influence of environmental insults on the onset and progression of mitochondrial diseases is unknown. To evaluate the effects of infection on mitochondrial disease we used a mouse model of Leigh Syndrome, where a missense mutation in the Taco1 gene results in the loss of the translation activator of cytochrome c oxidase subunit I (TACO1) protein. The mutation leads to an isolated complex IV deficiency that mimics the disease pathology observed in human patients with TACO1 mutations. We infected Taco1 mutant and wild-type mice with a murine cytomegalovirus and show that a common viral infection exacerbates the complex IV deficiency in a tissue-specific manner. We identified changes in neuromuscular morphology and tissue-specific regulation of the mammalian target of rapamycin pathway in response to viral infection. Taken together, we report for the first time that a common stress condition, such as viral infection, can exacerbate mitochondrial dysfunction in a genetic model of mitochondrial disease. Mitochondrial diseases are the most commonly inherited metabolic disorders that are heterogenic and have varied disease onset and progression. Acquired infections and the associated inflammatory responses are known triggers for mitochondrial disease in the clinic and can cause progressive deterioration in patients with mitochondrial disease. Knowledge of how an infection causes and contributes to the progression of mitochondrial disease is completely lacking and has never before been investigated. Here we examined the effects of a viral infection in a model of energy dysfunction and identified that cytomegalovirus can worsen the progression of mitochondrial disease symptoms.
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Affiliation(s)
- Nicola Ferreira
- Harry Perkins Institute of Medical Research, QEII Medical Centre, Nedlands, Western Australia, Australia
- Centre for Medical Research, The University of Western Australia, Nedlands, Western Australia, Australia
| | - Christopher E. Andoniou
- Infection and Immunity Program and Department of Microbiology, Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia
- Centre for Experimental Immunology, Lions Eye Institute, Perth, Western Australia, Australia
| | - Kara L. Perks
- Harry Perkins Institute of Medical Research, QEII Medical Centre, Nedlands, Western Australia, Australia
- Centre for Medical Research, The University of Western Australia, Nedlands, Western Australia, Australia
| | - Judith A. Ermer
- Harry Perkins Institute of Medical Research, QEII Medical Centre, Nedlands, Western Australia, Australia
- Centre for Medical Research, The University of Western Australia, Nedlands, Western Australia, Australia
| | - Danielle L. Rudler
- Harry Perkins Institute of Medical Research, QEII Medical Centre, Nedlands, Western Australia, Australia
- Centre for Medical Research, The University of Western Australia, Nedlands, Western Australia, Australia
| | - Giulia Rossetti
- Harry Perkins Institute of Medical Research, QEII Medical Centre, Nedlands, Western Australia, Australia
- Centre for Medical Research, The University of Western Australia, Nedlands, Western Australia, Australia
| | - Ambika Periyakaruppiah
- School of Biomedical Sciences, The University of Queensland, St. Lucia, Queensland, Australia
| | - Jamie K. Y. Wong
- School of Biomedical Sciences, The University of Queensland, St. Lucia, Queensland, Australia
| | - Oliver Rackham
- Harry Perkins Institute of Medical Research, QEII Medical Centre, Nedlands, Western Australia, Australia
- School of Pharmacy and Biomedical Sciences, Curtin University, Bentley, Western Australia, Australia
- Curtin Health Innovation Research Institute, Curtin University, Bentley, Western Australia, Australia
- Telethon Kids Institute, QEII Medical Centre, Nedlands, Western Australia, Australia
| | - Peter G. Noakes
- School of Biomedical Sciences, The University of Queensland, St. Lucia, Queensland, Australia
- Queensland Brain Institute, The University of Queensland, St. Lucia, Queensland, Australia
| | - Mariapia A. Degli-Esposti
- Infection and Immunity Program and Department of Microbiology, Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia
- Centre for Experimental Immunology, Lions Eye Institute, Perth, Western Australia, Australia
| | - Aleksandra Filipovska
- Harry Perkins Institute of Medical Research, QEII Medical Centre, Nedlands, Western Australia, Australia
- Centre for Medical Research, The University of Western Australia, Nedlands, Western Australia, Australia
- Telethon Kids Institute, QEII Medical Centre, Nedlands, Western Australia, Australia
- School of Molecular Sciences, The University of Western Australia, Crawley, Western Australia, Australia
- * E-mail:
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5
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O'Donnell L, Blakely EL, Baty K, Alexander M, Bogdanova-Mihaylova P, Craig J, Walsh R, Brett F, Taylor RW, Murphy SM. Chronic Progressive External Ophthalmoplegia due to a Rare de novo m.12334G>A MT-TL2 Mitochondrial DNA Variant1. J Neuromuscul Dis 2020; 7:355-360. [PMID: 32310184 DOI: 10.3233/jnd-200486] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
We describe a patient with chronic progressive external ophthalmoplegia (CPEO) due to a rare mitochondrial genetic variant. Muscle biopsy revealed numerous cytochrome c oxidase (COX)-deficient fibres, prompting sequencing of the entire mitochondrial genome in muscle which revealed a rare m.12334G>A variant in the mitochondrial (mt-) tRNALeu(CUN)(MT-TL2) gene. Analysis of several tissues showed this to be a de novo mutational event. Single fibre studies confirmed the segregation of high m.12334G>A heteroplasmy levels with the COX histochemical defect, confirming pathogenicity of the m.12334G>A MT-TL2 variant. This case illustrates the importance of pursuing molecular genetic analysis in clinically-affected tissues when mitochondrial disease is suspected.
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Affiliation(s)
- Luke O'Donnell
- Department of Neurology, Tallaght University Hospital, Tallaght, Dublin, Ireland
| | - Emma L Blakely
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, 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
| | - Karen Baty
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, 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
| | - Michael Alexander
- Department of Neurophysiology, Tallaght University Hospital, Tallaght, Dublin, Ireland
- Academic Unit of Neurology, Trinity College Dublin, The University of Dublin, Dublin, Ireland
| | | | - John Craig
- Department of Neurology, Belfast Health and Social Care Trust, Belfast, United Kingdom
| | - Ronan Walsh
- Department of Neurology, Hermitage Medical Clinic, Dublin, Ireland
| | - Francesca Brett
- Department of Neuropathology, Beaumont Hospital, Dublin, Ireland
| | - Robert W Taylor
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, 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
| | - Sinead M Murphy
- Department of Neurology, Tallaght University Hospital, Tallaght, Dublin, Ireland
- Academic Unit of Neurology, Trinity College Dublin, The University of Dublin, Dublin, Ireland
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Filograna R, Koolmeister C, Upadhyay M, Pajak A, Clemente P, Wibom R, Simard ML, Wredenberg A, Freyer C, Stewart JB, Larsson NG. Modulation of mtDNA copy number ameliorates the pathological consequences of a heteroplasmic mtDNA mutation in the mouse. Sci Adv 2019; 5:eaav9824. [PMID: 30949583 PMCID: PMC6447380 DOI: 10.1126/sciadv.aav9824] [Citation(s) in RCA: 72] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Accepted: 02/11/2019] [Indexed: 05/18/2023]
Abstract
Heteroplasmic mtDNA mutations typically act in a recessive way and cause mitochondrial disease only if present above a certain threshold level. We have experimentally investigated to what extent the absolute levels of wild-type (WT) mtDNA influence disease manifestations by manipulating TFAM levels in mice with a heteroplasmic mtDNA mutation in the tRNAAla gene. Increase of total mtDNA levels ameliorated pathology in multiple tissues, although the levels of heteroplasmy remained the same. A reduction in mtDNA levels worsened the phenotype in postmitotic tissues, such as heart, whereas there was an unexpected beneficial effect in rapidly proliferating tissues, such as colon, because of enhanced clonal expansion and selective elimination of mutated mtDNA. The absolute levels of WT mtDNA are thus an important determinant of the pathological manifestations, suggesting that pharmacological or gene therapy approaches to selectively increase mtDNA copy number provide a potential treatment strategy for human mtDNA mutation disease.
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Affiliation(s)
- R. Filograna
- Division of Molecular Metabolism, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, S-171 76 Stockholm, Sweden
- Max Planck Institute Biology of Ageing - Karolinska Institutet Laboratory, Karolinska Institutet, S-171 77 Stockholm, Sweden
| | - C. Koolmeister
- Division of Molecular Metabolism, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, S-171 76 Stockholm, Sweden
- Max Planck Institute Biology of Ageing - Karolinska Institutet Laboratory, Karolinska Institutet, S-171 77 Stockholm, Sweden
| | - M. Upadhyay
- Division of Molecular Metabolism, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, S-171 76 Stockholm, Sweden
- Max Planck Institute Biology of Ageing - Karolinska Institutet Laboratory, Karolinska Institutet, S-171 77 Stockholm, Sweden
| | - A. Pajak
- Division of Molecular Metabolism, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, S-171 76 Stockholm, Sweden
- Max Planck Institute Biology of Ageing - Karolinska Institutet Laboratory, Karolinska Institutet, S-171 77 Stockholm, Sweden
| | - P. Clemente
- Division of Molecular Metabolism, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, S-171 76 Stockholm, Sweden
- Max Planck Institute Biology of Ageing - Karolinska Institutet Laboratory, Karolinska Institutet, S-171 77 Stockholm, Sweden
| | - R. Wibom
- Center for Inherited Metabolic Diseases, Karolinska University Hospital, S-171 76 Stockholm, Sweden
| | - M. L. Simard
- Department of Mitochondrial Biology, Max Planck Institute for Biology of Ageing, D-50931 Cologne, Germany
| | - A. Wredenberg
- Division of Molecular Metabolism, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, S-171 76 Stockholm, Sweden
- Max Planck Institute Biology of Ageing - Karolinska Institutet Laboratory, Karolinska Institutet, S-171 77 Stockholm, Sweden
- Center for Inherited Metabolic Diseases, Karolinska University Hospital, S-171 76 Stockholm, Sweden
| | - C. Freyer
- Division of Molecular Metabolism, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, S-171 76 Stockholm, Sweden
- Max Planck Institute Biology of Ageing - Karolinska Institutet Laboratory, Karolinska Institutet, S-171 77 Stockholm, Sweden
- Center for Inherited Metabolic Diseases, Karolinska University Hospital, S-171 76 Stockholm, Sweden
| | - J. B. Stewart
- Department of Mitochondrial Biology, Max Planck Institute for Biology of Ageing, D-50931 Cologne, Germany
| | - N. G. Larsson
- Division of Molecular Metabolism, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, S-171 76 Stockholm, Sweden
- Max Planck Institute Biology of Ageing - Karolinska Institutet Laboratory, Karolinska Institutet, S-171 77 Stockholm, Sweden
- Center for Inherited Metabolic Diseases, Karolinska University Hospital, S-171 76 Stockholm, Sweden
- Department of Mitochondrial Biology, Max Planck Institute for Biology of Ageing, D-50931 Cologne, Germany
- Corresponding author.
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7
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Samanta D, Gokden M. PEHO syndrome: KIF1A mutation and decreased activity of mitochondrial respiratory chain complex. J Clin Neurosci 2018; 61:298-301. [PMID: 30385166 DOI: 10.1016/j.jocn.2018.10.091] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Accepted: 10/24/2018] [Indexed: 01/14/2023]
Abstract
We report a child with hypotonia, optic atrophy, progressive encephalopathy and intractable infantile spasms who was diagnosed with PEHO syndrome. Extensive investigation was performed to diagnose an underlying etiology. Electron transport chain activities in muscle biopsies showed an isolated complex IV deficiency. Genetic examination focused on complex IV genes such as mtDNA and relevant nuclear DNA analysis was unremarkable. Whole exome sequencing with trio revealed a heterozygous de novo mutation at c.757G>A (p.E253K) in the KIF1A gene. The protein encoded by this gene functions as an anterograde motor protein that transports membranous organelles along axonal microtubules. The relation between this genetic mutation and decreased activity of the mitochondrial respiratory chain complex is discussed in details. Our study further confirmed that the molecular basis of PEHO syndrome at least in a subset of patients is a dominant KIF1A variant affecting the motor domain of the protein. This is the first description of the decreased activity of mitochondrial respiratory chain complex in association with either PEHO syndrome or KIF1A mutation. This study emphasizes that the results of the mitochondrial enzymes should be interpreted with caution and clinicians should be actively looking for other underlying diagnoses with further comprehensive studies.
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Affiliation(s)
- Debopam Samanta
- Child Neurology Section, Department of Pediatrics, University of Arkansas for Medical Sciences, Little Rock, AR, United States.
| | - Murat Gokden
- Department of Pathology, University of Arkansas for Medical Sciences, Little Rock, AR, United States
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8
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Zhdanov AV, Andreev DE, Baranov PV, Papkovsky DB. Low energy costs of F1Fo ATP synthase reversal in colon carcinoma cells deficient in mitochondrial complex IV. Free Radic Biol Med 2017; 106:184-195. [PMID: 28189850 DOI: 10.1016/j.freeradbiomed.2017.02.025] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Revised: 02/08/2017] [Accepted: 02/08/2017] [Indexed: 10/20/2022]
Abstract
Mitochondrial polarisation is paramount for a variety of cellular functions. Under ischemia, mitochondrial membrane potential (ΔΨm) and proton gradient (ΔpH) are maintained via a reversal of mitochondrial F1Fo ATP synthase (mATPase), which can rapidly deplete ATP and drive cells into energy crisis. We found that under normal conditions in cells with disassembled cytochrome c oxidase complex (COX-deficient HCT116), mATPase maintains ΔΨm at levels only 15-20% lower than in WT cells, and for this utilises relatively little ATP. For a small energy expenditure, mATPase enables mitochondrial ΔpH, protein import, Ca2+ turnover, and supports free radical detoxication machinery enlarged to protect the cells from oxidative damage. Whereas in COX-deficient cells the main source of ATP is glycolysis, the ΔΨm is still maintained upon inhibition of the adenine nucleotide translocators with bongkrekic acid and carboxyatractyloside, indicating that the role of ANTs is redundant, and matrix substrate level phosphorylation alone or in cooperation with ATP-Mg/Pi carriers can continuously support the mATPase activity. Intriguingly, we found that mitochondrial complex III is active, and it contributes not only to free radical production, but also to ΔΨm maintenance and energy budget of COX-deficient cells. Overall, this study demonstrates that F1Fo ATP synthase can support general mitochondrial and cellular functions, working in extremely efficient 'energy saving' reverse mode and flexibly recruiting free radical detoxication and ATP producing / transporting pathways.
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Affiliation(s)
- Alexander V Zhdanov
- School of Biochemistry & Cell Biology, University College Cork, Cork, Ireland.
| | - Dmitry E Andreev
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia
| | - Pavel V Baranov
- School of Biochemistry & Cell Biology, University College Cork, Cork, Ireland
| | - Dmitri B Papkovsky
- School of Biochemistry & Cell Biology, University College Cork, Cork, Ireland
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Ravera S, Dufour C, Cesaro S, Bottega R, Faleschini M, Cuccarolo P, Corsolini F, Usai C, Columbaro M, Cipolli M, Savoia A, Degan P, Cappelli E. Evaluation of energy metabolism and calcium homeostasis in cells affected by Shwachman-Diamond syndrome. Sci Rep 2016; 6:25441. [PMID: 27146429 PMCID: PMC4857091 DOI: 10.1038/srep25441] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2015] [Accepted: 04/12/2016] [Indexed: 02/07/2023] Open
Abstract
Isomorphic mutation of the SBDS gene causes Shwachman-Diamond syndrome (SDS). SDS is a rare genetic bone marrow failure and cancer predisposition syndrome. SDS cells have ribosome biogenesis and their protein synthesis altered, which are two high-energy consuming cellular processes. The reported changes in reactive oxygen species production, endoplasmic reticulum stress response and reduced mitochondrial functionality suggest an energy production defect in SDS cells. In our work, we have demonstrated that SDS cells display a Complex IV activity impairment, which causes an oxidative phosphorylation metabolism defect, with a consequent decrease in ATP production. These data were confirmed by an increased glycolytic rate, which compensated for the energetic stress. Moreover, the signalling pathways involved in glycolysis activation also appeared more activated; i.e. we reported AMP-activated protein kinase hyper-phosphorylation. Notably, we also observed an increase in a mammalian target of rapamycin phosphorylation and high intracellular calcium concentration levels ([Ca(2+)]i), which probably represent new biochemical equilibrium modulation in SDS cells. Finally, the SDS cell response to leucine (Leu) was investigated, suggesting its possible use as a therapeutic adjuvant to be tested in clinical trials.
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Affiliation(s)
- Silvia Ravera
- DIFAR-Biochemistry Lab., Department of Pharmacy, University of Genova, 16132 Genova, Italy
| | - Carlo Dufour
- Haematology Unit, Istituto Giannina Gaslini, 16148 Genova, Italy
| | - Simone Cesaro
- Oncoematologia Pediatrica, Azienda Ospedaleira universitaria Integrata, Verona, Italy
| | - Roberta Bottega
- Department of Medical Sciences, University of Trieste, Trieste, Italy
| | - Michela Faleschini
- Institute for Maternal and Child Health – IRCCS Burlo Garofolo, Trieste, Italy
| | - Paola Cuccarolo
- S. C. Mutagenesis, IRCCS AOU San Martino – IST (Istituto Nazionale per la Ricerca sul Cancro), CBA Torre A2, 16123 Genova, Italy
| | - Fabio Corsolini
- Centro Diagnostica Genetica e Biochimica Malattie Metaboliche, Istituto Giannina Gaslini, 16148 Genova, Italy
| | - Cesare Usai
- Institute of Biophysics, National Research Council, 16149 Genova, Italy
| | - Marta Columbaro
- SC Laboratory of Musculoskeletal Cell Biology, IOR, Bologna, Italy
| | - Marco Cipolli
- Cystic Fibrosis Centre, Azienda Ospedaliera Universitaria, Piazzale Stefani, 1-37126 Verona, Italy
| | - Anna Savoia
- Institute for Maternal and Child Health – IRCCS Burlo Garofolo, Trieste, Italy
- Department of Medical Sciences, University of Trieste, Trieste, Italy
| | - Paolo Degan
- S. C. Mutagenesis, IRCCS AOU San Martino – IST (Istituto Nazionale per la Ricerca sul Cancro), CBA Torre A2, 16123 Genova, Italy
| | - Enrico Cappelli
- Haematology Unit, Istituto Giannina Gaslini, 16148 Genova, Italy
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10
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Abstract
As with other mitochondrial respiratory chain components, marked clinical and genetic heterogeneity is observed in patients with a cytochrome c oxidase deficiency. This constitutes a considerable diagnostic challenge and raises a number of puzzling questions. So far, pathological mutations have been reported in more than 30 genes, in both mitochondrial and nuclear DNA, affecting either structural subunits of the enzyme or proteins involved in its biogenesis. In this review, we discuss the possible causes of the discrepancy between the spectacular advances made in the identification of the molecular bases of cytochrome oxidase deficiency and the lack of any efficient treatment in diseases resulting from such deficiencies. This brings back many unsolved questions related to the frequent delay of clinical manifestation, variable course and severity, and tissue-involvement often associated with these diseases. In this context, we stress the importance of studying different models of these diseases, but also discuss the limitations encountered in most available disease models. In the future, with the possible exception of replacement therapy using genes, cells or organs, a better understanding of underlying mechanism(s) of these mitochondrial diseases is presumably required to develop efficient therapy.
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Affiliation(s)
- Malgorzata Rak
- Institut National de la Santé et de la Recherche Médicale Unité Mixte de Recherche 1141, Hôpital Robert Debré, 48 Boulevard Sérurier, 75019 Paris, France Faculté de Médecine Denis Diderot, Université Paris Diderot-Paris 7, Site Robert Debré, 48 Boulevard Sérurier, 75019 Paris, France
| | - Paule Bénit
- Institut National de la Santé et de la Recherche Médicale Unité Mixte de Recherche 1141, Hôpital Robert Debré, 48 Boulevard Sérurier, 75019 Paris, France Faculté de Médecine Denis Diderot, Université Paris Diderot-Paris 7, Site Robert Debré, 48 Boulevard Sérurier, 75019 Paris, France
| | - Dominique Chrétien
- Institut National de la Santé et de la Recherche Médicale Unité Mixte de Recherche 1141, Hôpital Robert Debré, 48 Boulevard Sérurier, 75019 Paris, France Faculté de Médecine Denis Diderot, Université Paris Diderot-Paris 7, Site Robert Debré, 48 Boulevard Sérurier, 75019 Paris, France
| | - Juliette Bouchereau
- Institut National de la Santé et de la Recherche Médicale Unité Mixte de Recherche 1141, Hôpital Robert Debré, 48 Boulevard Sérurier, 75019 Paris, France Faculté de Médecine Denis Diderot, Université Paris Diderot-Paris 7, Site Robert Debré, 48 Boulevard Sérurier, 75019 Paris, France
| | - Manuel Schiff
- Institut National de la Santé et de la Recherche Médicale Unité Mixte de Recherche 1141, Hôpital Robert Debré, 48 Boulevard Sérurier, 75019 Paris, France Faculté de Médecine Denis Diderot, Université Paris Diderot-Paris 7, Site Robert Debré, 48 Boulevard Sérurier, 75019 Paris, France Reference Center for Inherited Metabolic Diseases, Hôpital Robert Debré, Assistance Publique-Hôpitaux de Paris, 48 Boulevard Sérurier, 75019 Paris, France
| | - Riyad El-Khoury
- American University of Beirut Medical Center, Department of Pathology and Laboratory Medicine, Cairo Street, Hamra, Beirut, Lebanon
| | - Alexander Tzagoloff
- Biological Sciences Department, Columbia University, New York, NY 10027, U.S.A
| | - Pierre Rustin
- Institut National de la Santé et de la Recherche Médicale Unité Mixte de Recherche 1141, Hôpital Robert Debré, 48 Boulevard Sérurier, 75019 Paris, France Faculté de Médecine Denis Diderot, Université Paris Diderot-Paris 7, Site Robert Debré, 48 Boulevard Sérurier, 75019 Paris, France
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11
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Campbell G, Krishnan KJ, Deschauer M, Taylor RW, Turnbull DM. Dissecting the mechanisms underlying the accumulation of mitochondrial DNA deletions in human skeletal muscle. Hum Mol Genet 2014; 23:4612-20. [PMID: 24740879 PMCID: PMC4119413 DOI: 10.1093/hmg/ddu176] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2014] [Revised: 04/09/2014] [Accepted: 04/09/2014] [Indexed: 01/07/2023] Open
Abstract
Large-scale mitochondrial DNA (mtDNA) deletions are an important cause of mitochondrial disease, while somatic mtDNA deletions cause focal respiratory chain deficiency associated with ageing and neurodegenerative disorders. As mtDNA deletions only cause cellular pathology at high levels of mtDNA heteroplasmy, an mtDNA deletion must accumulate to levels which can result in biochemical dysfunction-a process known as clonal expansion. A number of hypotheses have been proposed for clonal expansion of mtDNA deletions, including a replicative advantage for deleted mitochondrial genomes inferred by their smaller size--implying that the largest mtDNA deletions would also display a replicative advantage over smaller mtDNA deletions. We proposed that in muscle fibres from patients with mtDNA maintenance disorders, which lead to the accumulation of multiple mtDNA deletions, we would observe the largest mtDNA deletions spreading the furthest longitudinally through individual muscle fibres by means of a greater rate of clonal expansion. We characterized mtDNA deletions in patients with mtDNA maintenance disorders from a range of 'large' and 'small' cytochrome c oxidase (COX)-deficient regions in skeletal muscle fibres. We measured the size of clonally expanded deletions in 62 small and 60 large individual COX-deficient f regions. No significant difference was observed in individual patients or in the total dataset (small fibre regions mean 6.59 kb--large fibre regions mean 6.51 kb). Thus no difference existed in the rate of clonal expansion throughout muscle fibres between mtDNA deletions of different sizes; smaller mitochondrial genomes therefore do not appear to have an inherent replicative advantage in human muscle.
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Affiliation(s)
- Georgia Campbell
- Wellcome Trust Centre for Mitochondrial Research, and Newcastle University Centre for Brain Ageing and Vitality, Institute for Ageing and Health, Newcastle University, Newcastle upon Tyne, UK
| | - Kim J Krishnan
- Wellcome Trust Centre for Mitochondrial Research, and Newcastle University Centre for Brain Ageing and Vitality, Institute for Ageing and Health, Newcastle University, Newcastle upon Tyne, UK
| | - Marcus Deschauer
- Department of Neurology, Martin-Luther-University Halle-Wittenberg, Ernst-Grube Str. 40, Halle (Saale) D-06120, Germany
| | | | - Doug M Turnbull
- Wellcome Trust Centre for Mitochondrial Research, and Newcastle University Centre for Brain Ageing and Vitality, Institute for Ageing and Health, Newcastle University, Newcastle upon Tyne, UK
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12
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Yarham JW, Lamichhane TN, Pyle A, Mattijssen S, Baruffini E, Bruni F, Donnini C, Vassilev A, He L, Blakely EL, Griffin H, Santibanez-Koref M, Bindoff LA, Ferrero I, Chinnery PF, McFarland R, Maraia RJ, Taylor RW. Defective i6A37 modification of mitochondrial and cytosolic tRNAs results from pathogenic mutations in TRIT1 and its substrate tRNA. PLoS Genet 2014; 10:e1004424. [PMID: 24901367 PMCID: PMC4046958 DOI: 10.1371/journal.pgen.1004424] [Citation(s) in RCA: 102] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2013] [Accepted: 04/20/2014] [Indexed: 01/10/2023] Open
Abstract
Identifying the genetic basis for mitochondrial diseases is technically challenging given the size of the mitochondrial proteome and the heterogeneity of disease presentations. Using next-generation exome sequencing, we identified in a patient with severe combined mitochondrial respiratory chain defects and corresponding perturbation in mitochondrial protein synthesis, a homozygous p.Arg323Gln mutation in TRIT1. This gene encodes human tRNA isopentenyltransferase, which is responsible for i6A37 modification of the anticodon loops of a small subset of cytosolic and mitochondrial tRNAs. Deficiency of i6A37 was previously shown in yeast to decrease translational efficiency and fidelity in a codon-specific manner. Modelling of the p.Arg323Gln mutation on the co-crystal structure of the homologous yeast isopentenyltransferase bound to a substrate tRNA, indicates that it is one of a series of adjacent basic side chains that interact with the tRNA backbone of the anticodon stem, somewhat removed from the catalytic center. We show that patient cells bearing the p.Arg323Gln TRIT1 mutation are severely deficient in i6A37 in both cytosolic and mitochondrial tRNAs. Complete complementation of the i6A37 deficiency of both cytosolic and mitochondrial tRNAs was achieved by transduction of patient fibroblasts with wild-type TRIT1. Moreover, we show that a previously-reported pathogenic m.7480A>G mt-tRNASer(UCN) mutation in the anticodon loop sequence A36A37A38 recognised by TRIT1 causes a loss of i6A37 modification. These data demonstrate that deficiencies of i6A37 tRNA modification should be considered a potential mechanism of human disease caused by both nuclear gene and mitochondrial DNA mutations while providing insight into the structure and function of TRIT1 in the modification of cytosolic and mitochondrial tRNAs. Mitochondrial disorders are clinically diverse, and identifying the underlying genetic mutations is technically challenging due to the large number of mitochondrial proteins. Using high-throughput sequencing technology, we identified a disease-causing mutation in the TRIT1 gene. This gene encodes an enzyme, tRNA isopentenyltransferase, that adds an N6-isopentenyl modification to adenosine-37 (i6A37) in a small number of tRNAs, enabling them to function correctly during the synthesis of essential mitochondrial proteins. We show that this mutation leads to severe deficiency of tRNA-i6A37 in the patient's cells that can be rescued by introduction of the wild-type TRIT1 protein. A deficiency in oxidative phosphorylation, the process by which energy (ATP) is generated in the mitochondria, leads to a mitochondrial disease presentation. Introducing the mutant protein into model yeast species and measuring the resulting impairment provided further evidence of the pathogenic effect of the mutation. Additional studies investigating a previously reported pathogenic mutation in a mitochondrial tRNA gene demonstrated that a mutation in a substrate of TRIT1 can also cause a loss of the modification, providing evidence of a new mechanism causing mitochondrial disease in humans.
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Affiliation(s)
- John W. Yarham
- Wellcome Trust Centre for Mitochondrial Research, Institute for Ageing and Health, The Medical School, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Tek N. Lamichhane
- Intramural Research Program, NICHD, NIH, Bethesda, Maryland, United States of America
| | - Angela Pyle
- Wellcome Trust Centre for Mitochondrial Research, Institute for Genetic Medicine, The Medical School, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Sandy Mattijssen
- Intramural Research Program, NICHD, NIH, Bethesda, Maryland, United States of America
| | | | - Francesco Bruni
- Wellcome Trust Centre for Mitochondrial Research, Institute for Ageing and Health, The Medical School, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Claudia Donnini
- Department of Life Sciences, University of Parma, Parma, Italy
| | - Alex Vassilev
- Intramural Research Program, NICHD, NIH, Bethesda, Maryland, United States of America
| | - Langping He
- Wellcome Trust Centre for Mitochondrial Research, Institute for Ageing and Health, The Medical School, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Emma L. Blakely
- Wellcome Trust Centre for Mitochondrial Research, Institute for Ageing and Health, The Medical School, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Helen Griffin
- Wellcome Trust Centre for Mitochondrial Research, Institute for Genetic Medicine, The Medical School, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Mauro Santibanez-Koref
- Wellcome Trust Centre for Mitochondrial Research, Institute for Genetic Medicine, The Medical School, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Laurence A. Bindoff
- Department of Neurology, Haukeland University Hospital, Bergen, Norway
- Department of Clinical Medicine, University of Bergen, Bergen, Norway
| | - Ileana Ferrero
- Department of Life Sciences, University of Parma, Parma, Italy
| | - Patrick F. Chinnery
- Wellcome Trust Centre for Mitochondrial Research, Institute for Genetic Medicine, The Medical School, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Robert McFarland
- Wellcome Trust Centre for Mitochondrial Research, Institute for Ageing and Health, The Medical School, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Richard J. Maraia
- Intramural Research Program, NICHD, NIH, Bethesda, Maryland, United States of America
- * E-mail: (RJM) (RM); (RWT) (RT)
| | - Robert W. Taylor
- Wellcome Trust Centre for Mitochondrial Research, Institute for Ageing and Health, The Medical School, Newcastle University, Newcastle upon Tyne, United Kingdom
- * E-mail: (RJM) (RM); (RWT) (RT)
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13
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Bourens M, Boulet A, Leary SC, Barrientos A. Human COX20 cooperates with SCO1 and SCO2 to mature COX2 and promote the assembly of cytochrome c oxidase. Hum Mol Genet 2014; 23:2901-13. [PMID: 24403053 DOI: 10.1093/hmg/ddu003] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Cytochrome c oxidase (CIV) deficiency is one of the most common respiratory chain defects in patients presenting with mitochondrial encephalocardiomyopathies. CIV biogenesis is complicated by the dual genetic origin of its structural subunits, and assembly of a functional holoenzyme complex requires a large number of nucleus-encoded assembly factors. In general, the functions of these assembly factors remain poorly understood, and mechanistic investigations of human CIV biogenesis have been limited by the availability of model cell lines. Here, we have used small interference RNA and transcription activator-like effector nucleases (TALENs) technology to create knockdown and knockout human cell lines, respectively, to study the function of the CIV assembly factor COX20 (FAM36A). These cell lines exhibit a severe, isolated CIV deficiency due to instability of COX2, a mitochondrion-encoded CIV subunit. Mitochondria lacking COX20 accumulate CIV subassemblies containing COX1 and COX4, similar to those detected in fibroblasts from patients carrying mutations in the COX2 copper chaperones SCO1 and SCO2. These results imply that in the absence of COX20, COX2 is inefficiently incorporated into early CIV subassemblies. Immunoprecipitation assays using a stable COX20 knockout cell line expressing functional COX20-FLAG allowed us to identify an interaction between COX20 and newly synthesized COX2. Additionally, we show that SCO1 and SCO2 act on COX20-bound COX2. We propose that COX20 acts as a chaperone in the early steps of COX2 maturation, stabilizing the newly synthesized protein and presenting COX2 to its metallochaperone module, which in turn facilitates the incorporation of mature COX2 into the CIV assembly line.
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14
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Rodinová M, Trefilová E, Honzík T, Tesařová M, Zeman J, Hansíková H. Non-invasive screening of cytochrome c oxidase deficiency in children using a dipstick immunocapture assay. Folia Biol (Praha) 2014; 60:268-274. [PMID: 25629267] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Cytochrome c oxidase (CIV) deficiency is among the most common childhood mitochondrial disorders. The diagnosis of this deficiency is complex, and muscle biopsy is used as the gold standard of diagnosis. Our aim was to minimize the patient burden and to test the use of a dipstick immunocapture assay (DIA) to determine the amount of CIV in non-invasively obtained buccal epithelial cells. Buccal smears were obtained from five children with Leigh syndrome including three children exhibiting a previously confirmed CIV deficiency in muscle and fibroblasts and two children who were clinical suspects for CIV deficiency; the smear samples were analysed using CI and CIV human protein quantity dipstick assay kits. Samples from five children of similar age and five adults were used as controls. Analysis of the controls demonstrated that only samples of buccal cells that were frozen for a maximum of 4 h after collection provide accurate results. All three patients with confirmed CIV deficiency due to mutations in the SURF1 gene exhibited significantly lower amounts of CIV than the similarly aged controls; significantly lower amounts were also observed in two new patients, for whom later molecular analysis also confirmed pathologic mutations in the SURF1 gene. We conclude that DIA is a simple, fast and sensitive method for the determination of CIV in buccal cells and is suitable for the screening of CIV deficiency in non-invasively obtained material from children who are suspected of having mitochondrial disease.
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Affiliation(s)
- M Rodinová
- Laboratory for the Study of Mitochondrial Disorders, Department of Paediatrics and Adolescent Medicine, First Faculty of Medicine, Charles University and General University Hospital in Prague, Czech Republic
| | - E Trefilová
- Laboratory for the Study of Mitochondrial Disorders, Department of Paediatrics and Adolescent Medicine, First Faculty of Medicine, Charles University and General University Hospital in Prague, Czech Republic
| | - T Honzík
- Laboratory for the Study of Mitochondrial Disorders, Department of Paediatrics and Adolescent Medicine, First Faculty of Medicine, Charles University and General University Hospital in Prague, Czech Republic
| | - M Tesařová
- Laboratory for the Study of Mitochondrial Disorders, Department of Paediatrics and Adolescent Medicine, First Faculty of Medicine, Charles University and General University Hospital in Prague, Czech Republic
| | - J Zeman
- Laboratory for the Study of Mitochondrial Disorders, Department of Paediatrics and Adolescent Medicine, First Faculty of Medicine, Charles University and General University Hospital in Prague, Czech Republic
| | - H Hansíková
- Laboratory for the Study of Mitochondrial Disorders, Department of Paediatrics and Adolescent Medicine, First Faculty of Medicine, Charles University and General University Hospital in Prague, Czech Republic
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15
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Almalki A, Alston CL, Parker A, Simonic I, Mehta SG, He L, Reza M, Oliveira JM, Lightowlers RN, McFarland R, Taylor RW, Chrzanowska-Lightowlers ZM. Mutation of the human mitochondrial phenylalanine-tRNA synthetase causes infantile-onset epilepsy and cytochrome c oxidase deficiency. Biochim Biophys Acta 2014; 1842:56-64. [PMID: 24161539 PMCID: PMC3898479 DOI: 10.1016/j.bbadis.2013.10.008] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Revised: 09/30/2013] [Accepted: 10/17/2013] [Indexed: 11/24/2022]
Abstract
Mitochondrial aminoacyl-tRNA synthetases (aaRSs) are essential enzymes in protein synthesis since they charge tRNAs with their cognate amino acids. Mutations in the genes encoding mitochondrial aaRSs have been associated with a wide spectrum of human mitochondrial diseases. Here we report the identification of pathogenic mutations (a partial genomic deletion and a highly conserved p. Asp325Tyr missense variant) in FARS2, the gene encoding mitochondrial phenylalanyl-tRNA synthetase, in a patient with early-onset epilepsy and isolated complex IV deficiency in muscle. The biochemical defect was expressed in myoblasts but not in fibroblasts and associated with decreased steady state levels of COXI and COXII protein and reduced steady state levels of the mt-tRNA(Phe) transcript. Functional analysis of the recombinant mutant p. Asp325Tyr FARS2 protein showed an inability to bind ATP and consequently undetectable aminoacylation activity using either bacterial tRNA or human mt-tRNA(Phe) as substrates. Lentiviral transduction of cells with wildtype FARS2 restored complex IV protein levels, confirming that the p.Asp325Tyr mutation is pathogenic, causing respiratory chain deficiency and neurological deficits on account of defective aminoacylation of mt-tRNA(Phe).
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Affiliation(s)
- Abdulraheem Almalki
- Wellcome Trust Centre for Mitochondrial Research, Institute for Ageing and Health, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Charlotte L. Alston
- Wellcome Trust Centre for Mitochondrial Research, Institute for Ageing and Health, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Alasdair Parker
- Child Development Centre, Addenbrooke's Hospital, Cambridge, UK
| | - Ingrid Simonic
- Medical Genetics Laboratories, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK
| | - Sarju G. Mehta
- Department of Medical Genetics, Addenbrookes Hospital, Cambridge, UK
| | - Langping He
- Wellcome Trust Centre for Mitochondrial Research, Institute for Ageing and Health, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Mojgan Reza
- Biobank, Institute for Genetic Medicine, Newcastle University, International Centre for Life, Central Parkway, Newcastle upon Tyne NE1 3BZ, UK
| | - Jorge M.A. Oliveira
- Wellcome Trust Centre for Mitochondrial Research, Institute for Ageing and Health, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Robert N. Lightowlers
- The Wellcome Trust Centre for Mitochondrial Research, Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Robert McFarland
- Wellcome Trust Centre for Mitochondrial Research, Institute for Ageing and Health, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Robert W. Taylor
- Wellcome Trust Centre for Mitochondrial Research, Institute for Ageing and Health, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Zofia M.A. Chrzanowska-Lightowlers
- Wellcome Trust Centre for Mitochondrial Research, Institute for Ageing and Health, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
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16
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Roos S, Darin N, Kollberg G, Andersson Grönlund M, Tulinius M, Holme E, Moslemi AR, Oldfors A. A novel mitochondrial tRNA Arg mutation resulting in an anticodon swap in a patient with mitochondrial encephalomyopathy. Eur J Hum Genet 2013; 21:571-3. [PMID: 22781096 PMCID: PMC3641373 DOI: 10.1038/ejhg.2012.153] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2011] [Revised: 06/04/2012] [Accepted: 06/13/2012] [Indexed: 11/08/2022] Open
Abstract
We report a mutation in the anticodon of the tRNA(Arg) gene (m.10437 G>A), resulting in an anticodon swap from GCU to ACU, which is the anticodon of tRNA(Trp), in a boy with mitochondrial encephalomyopathy. Enzyme histochemical analysis of muscle tissue and biochemical analysis of isolated muscle mitochondria demonstrated cytochrome c oxidase (COX) deficiency. Restriction fragment length polymorphism analysis showed that 90% of muscle and 82% of urinary epithelium mtDNA harbored the mutation. The mutation was not identified in blood, fibroblasts, hair roots, or buccal epithelial cells and it was absent in the asymptomatic mother, suggesting that it was a de novo mutation. Single-fiber PCR analysis showed that the proportion of mutated mtDNA correlated with enzyme histochemical COX deficiency. This mutation adds to the three previously described disease-causing mutations in tRNA(Arg), but it is the first mutation occurring in the anticodon of tRNA(Arg).
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Affiliation(s)
- Sara Roos
- Department of Pathology, Institute of Biomedicine, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden.
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17
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Markaryan A, Nelson EG, Hinojosa R. Major arc mitochondrial DNA deletions in cytochrome c oxidase-deficient human cochlear spiral ganglion cells. Acta Otolaryngol 2010; 130:780-7. [PMID: 20085441 DOI: 10.3109/00016480903397702] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
CONCLUSIONS This study suggests that cytochrome c oxidase subunit 3 (COX 3) expression is diminished in spiral ganglion cells from individuals with presbycusis. In addition to the mitochondrial DNA (mtDNA) common deletion (CD), other deletions involving the mtDNA major arc contribute to the observed deficit in COX 3 expression. OBJECTIVES To assess COX 3 deficiency in spiral ganglion cells from individuals with presbycusis and to determine whether deletions other than the CD contribute to this deficiency. METHODS COX 3 immunofluorescence staining of archival human temporal bone tissue sections from individuals with presbycusis and from age-matched normal-hearing individuals was performed and the intensity of spiral ganglion cell immunostaining was measured. Single COX 3-deficient spiral ganglion cells were isolated by laser microdissection (LMD) and the DNA was analyzed with duplex real-time PCR assays to assess the CD level and the total mtDNA major arc deletion level. RESULTS A statistically significant difference (p = 0.021) in the mean intensity of COX 3 immunofluorescence staining of spiral ganglion cells was observed between individuals with presbycusis and normal-hearing controls. The total mtDNA major arc deletion level was greater than the CD level in COX 3-deficient spiral ganglion cells.
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18
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Yu-Wai-Man P, Sitarz KS, Samuels DC, Griffiths PG, Reeve AK, Bindoff LA, Horvath R, Chinnery PF. OPA1 mutations cause cytochrome c oxidase deficiency due to loss of wild-type mtDNA molecules. Hum Mol Genet 2010; 19:3043-52. [PMID: 20484224 PMCID: PMC2901142 DOI: 10.1093/hmg/ddq209] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Pathogenic OPA1 mutations cause autosomal dominant optic atrophy (DOA), a condition characterized by the preferential loss of retinal ganglion cells and progressive optic nerve degeneration. Approximately 20% of affected patients will also develop more severe neuromuscular complications, an important disease subgroup known as DOA+. Cytochrome c oxidase (COX)-negative fibres and multiple mitochondrial DNA (mtDNA) deletions have been identified in skeletal muscle biopsies from patients manifesting both the pure and syndromal variants, raising the possibility that the accumulation of somatic mtDNA defects contribute to the disease process. In this study, we investigated the mtDNA changes induced by OPA1 mutations in skeletal muscle biopsies from 15 patients with both pure DOA and DOA+ phenotypes. We observed a 2- to 4-fold increase in mtDNA copy number at the single-fibre level, and patients with DOA+ features had significantly greater mtDNA proliferation in their COX-negative skeletal muscle fibres compared with patients with isolated optic neuropathy. Low levels of wild-type mtDNA molecules were present in COX-deficient muscle fibres from both pure DOA and DOA+ patients, implicating haplo-insufficiency as the mechanism responsible for the biochemical defect. Our findings are consistent with the ‘maintenance of wild-type’ hypothesis, the secondary mtDNA deletions induced by OPA1 mutations triggering a compensatory mitochondrial proliferative response in order to maintain an optimal level of wild-type mtDNA genomes. However, when deletion levels reach a critical level, further mitochondrial proliferation leads to replication of the mutant species at the expense of wild-type mtDNA, resulting in the loss of respiratory chain COX activity.
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Affiliation(s)
- Patrick Yu-Wai-Man
- Mitochondrial Research Group, Institute for Ageing and Health, The Medical School, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
- Department of Ophthalmology, Royal Victoria Infirmary, Newcastle upon Tyne, UK
| | - Kamil S. Sitarz
- Mitochondrial Research Group, Institute for Ageing and Health, The Medical School, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - David C. Samuels
- Department of Molecular Physiology and Biophysics, Center for Human Genetics Research, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Philip G. Griffiths
- Mitochondrial Research Group, Institute for Ageing and Health, The Medical School, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
- Department of Ophthalmology, Royal Victoria Infirmary, Newcastle upon Tyne, UK
| | - Amy K. Reeve
- Mitochondrial Research Group, Institute for Ageing and Health, The Medical School, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Laurence A. Bindoff
- Department of Clinical Medicine, University of Bergen, Bergen, Norway
- Department of Neurology, Haukeland University Hospital, Bergen, Norway and
| | - Rita Horvath
- Mitochondrial Research Group, Institute for Ageing and Health, The Medical School, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Patrick F. Chinnery
- Mitochondrial Research Group, Institute for Ageing and Health, The Medical School, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
- Institute of Human Genetics, Newcastle University, Newcastle upon Tyne, UK
- To whom correspondence should be addressed. Tel: +44 1912824375; Fax: +44 1912824373;
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19
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Davidson MM, Walker WF, Hernandez-Rosa E, Nesti C. Evidence for nuclear modifier gene in mitochondrial cardiomyopathy. J Mol Cell Cardiol 2009; 46:936-42. [PMID: 19233192 PMCID: PMC2741011 DOI: 10.1016/j.yjmcc.2009.02.011] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2008] [Revised: 02/02/2009] [Accepted: 02/02/2009] [Indexed: 11/29/2022]
Abstract
Mitochondrial DNA (mtDNA) inheritance and maintenance and function of the respiratory chain are the result of a synergistic action of the nuclear and the mitochondrial genomes. Mutations in either or both genomes can result in a wide range of multisystemic disorders. We have studied a homoplasmic mtDNA mutation in the tRNA(Ile) gene that segregates exclusively with cardiomyopathy in two unrelated families. Cytochrome c oxidase (COX) deficiency was selectively observed only in the heart tissue and in patient's cardiomyocyte cultures and not in any other cell type, indicating that the defect is tissue specific. To understand the pathogenic mechanism of cardiomyopathy associated with a homoplasmic, tissue specific mtDNA mutation, we constructed transnuclear cardiomyocyte cell lines with normal or patient's nucleus and containing wild type or mutant mtDNA. Of the four cell lines analyzed, COX activity was low only in patient's cardiomyocytes illustrating that both the patient's nucleus and mitochondria are essential for expression of the phenotype. In cells with either wild type nucleus or wild type mtDNA, COX activity was normal. From these results it is evident that a tissue specific nuclear modifier gene may interact synergistically with the mtDNA mutation to cause COX deficiency.
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Affiliation(s)
- Mercy M Davidson
- Department of Neurology, Columbia University, Russ Berrie Medical Pavilion, NY 10032, USA.
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20
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Piekutowska-Abramczuk D, Popowska E, Pronicki M, Karczmarewicz E, Tylek-Lemanska D, Sykut-Cegielska J, Szymanska-Dembinska T, Bielecka L, Krajewska-Walasek M, Pronicka E. High prevalence of SURF1 c.845_846delCT mutation in Polish Leigh patients. Eur J Paediatr Neurol 2009; 13:146-53. [PMID: 18583168 DOI: 10.1016/j.ejpn.2008.03.009] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/06/2007] [Revised: 03/12/2008] [Accepted: 03/17/2008] [Indexed: 11/19/2022]
Abstract
Leigh syndrome is a neuropathological disorder with typical morphological changes in brain, appearing regardless of diverse molecular background. One of the most common enzymatic defects in Leigh patients is cytochrome c oxidase deficiency associated with recessive mutations in the SURF1 gene. To assess the SURF1 mutation profile among Polish patients we studied 41 affected children from 34 unrelated families by PCR-SSCP and sequencing. Four novel mutations, c.39delG, c.752-1G>C, c.800_801insT, c.821A>G, and five described pathogenic changes, c.311_312insAT312_321del10, c.688C>T, c.704T>C, c.756_757delCA, c.845_846delCT, were identified in 85.3% of analysed probands. One mutation, c.845_846delCT, was identified in 77.6% of SURF1 alleles. Up to now, it has been reported only in 9% of alleles in other parts of the world. The deletion was used as LS(SURF1-) marker in population studies. Eight heterozygous carriers of the mutation were found in a cohort of 2890 samples. The estimated c.845_846delCT allele frequency is 1:357 (0.28+/-0.2%), and the lowest predicted LS(SURF1-) frequency in Poland 1:126,736.births. Relatively high frequency of LS(SURF1-) in Poland with remarkable c.845_846delCT mutation dominance allows one to start the differential diagnosis of LS in each patient of Polish (and probably Slavonic) origin from the direct search for c.845_846delCT SURF1 mutation.
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Affiliation(s)
- Dorota Piekutowska-Abramczuk
- Department of Medical Genetics, Children's Memorial Health Institute, Al. Dzieci Polskich 20, 04-730 Warsaw, Poland.
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21
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Ghezzi D, Saada A, D'Adamo P, Fernandez-Vizarra E, Gasparini P, Tiranti V, Elpeleg O, Zeviani M. FASTKD2 nonsense mutation in an infantile mitochondrial encephalomyopathy associated with cytochrome c oxidase deficiency. Am J Hum Genet 2008; 83:415-23. [PMID: 18771761 PMCID: PMC2556431 DOI: 10.1016/j.ajhg.2008.08.009] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2008] [Revised: 08/13/2008] [Accepted: 08/14/2008] [Indexed: 12/28/2022] Open
Abstract
In two siblings we found a mitochondrial encephalomyopathy, characterized by developmental delay, hemiplegia, convulsions, asymmetrical brain atrophy, and low cytochrome c oxidase (COX) activity in skeletal muscle. The disease locus was identified on chromosome 2 by homozygosity mapping; candidate genes were prioritized for their known or predicted mitochondrial localization and then sequenced in probands and controls. A homozygous nonsense mutation in the KIAA0971 gene segregated with the disease in the proband family. The corresponding protein is known as fas activated serine-threonine kinase domain 2, FASTKD2. Confocal immunofluorescence colocalized a tagged recombinant FASTKD2 protein with mitochondrial markers, and membrane-potential-dependent in vitro mitochondrial import was demonstrated in isolated mitochondria. In staurosporine-induced-apoptosis experiments, decreased nuclear fragmentation was detected in treated mutant versus control fibroblasts. In conclusion, we found a loss-of-function mutation in a gene segregating with a peculiar mitochondrial encephalomyopathy associated with COX deficiency in skeletal muscle. The corresponding protein is localized in the mitochondrial inner compartment. Preliminary data indicate that FASTKD2 plays a role in mitochondrial apoptosis.
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Affiliation(s)
- Daniele Ghezzi
- Division of Molecular Neurogenetics, Foundation IRCCS Neurological Institute “C. Besta,” 20126 Milan, Italy
| | - Ann Saada
- Metabolic Disease Unit, Hadassah-Hebrew University Medical Center, 91120 Jerusalem, Israel
| | - Pio D'Adamo
- Division of Medical Genetics, IRCCS Burlo Garofolo - University of Trieste, 34137 Trieste, Italy
| | - Erika Fernandez-Vizarra
- Division of Molecular Neurogenetics, Foundation IRCCS Neurological Institute “C. Besta,” 20126 Milan, Italy
| | - Paolo Gasparini
- Division of Medical Genetics, IRCCS Burlo Garofolo - University of Trieste, 34137 Trieste, Italy
| | - Valeria Tiranti
- Division of Molecular Neurogenetics, Foundation IRCCS Neurological Institute “C. Besta,” 20126 Milan, Italy
| | - Orly Elpeleg
- Metabolic Disease Unit, Hadassah-Hebrew University Medical Center, 91120 Jerusalem, Israel
| | - Massimo Zeviani
- Division of Molecular Neurogenetics, Foundation IRCCS Neurological Institute “C. Besta,” 20126 Milan, Italy
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22
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Massa V, Fernandez-Vizarra E, Alshahwan S, Bakhsh E, Goffrini P, Ferrero I, Mereghetti P, D'Adamo P, Gasparini P, Zeviani M. Severe infantile encephalomyopathy caused by a mutation in COX6B1, a nucleus-encoded subunit of cytochrome c oxidase. Am J Hum Genet 2008; 82:1281-9. [PMID: 18499082 DOI: 10.1016/j.ajhg.2008.05.002] [Citation(s) in RCA: 134] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2008] [Revised: 04/30/2008] [Accepted: 05/02/2008] [Indexed: 01/08/2023] Open
Abstract
Cytochrome c oxidase (COX) deficiency, one of the most common respiratory-chain defects in humans, has been associated with mutations in either mitochondrial DNA genes or nucleus-encoded proteins that are not part in but promote the biogenesis of COX. Mutations of nucleus-encoded structural subunits were sought for but never found in COX-defective patients, leading to the conjecture that they may be incompatible with extra-uterine survival. We report a disease-associated mutation in one such subunit, COX6B1. Nuclear-encoded COX genes should be reconsidered and included in the diagnostic mutational screening of human disorders related to COX deficiency.
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Affiliation(s)
- Valeria Massa
- Department of Molecular Neurogenetics, Foundation IRCCS Neurological Institute C. Besta, 20126 Milano, Italy
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23
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Piekutowska-Abramczuk D. [The molecular background of Leigh syndrome]. Neurol Neurochir Pol 2008; 42:238-250. [PMID: 18651330] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Leigh syndrome (subacute necrotizing encephalomyopathy, MIM 256,000) is a progressive neurodegenerative disorder of infancy and childhood, with characteristic pathological hallmarks including symmetric necrotizing lesions in the brainstem, basal ganglia, thalamus and spinal cord. It may result from several defects of mitochondrial enzyme complexes, including pyruvate dehydrogenase complex, and respiratory chain complexes I, II, III, IV, V. Clinical presentation mostly includes failure to thrive, developmental delay, muscle weakness, hypotonia, disorders of ocular movements, abnormal respiratory rate and bulbar dysfunction. Symptoms usually start after a few months of normal development and the course is typically rapid and relentless. Affected patients usually die before 5 years of life due to central ventilation failure. Leigh syndrome occurs with an estimated frequency of 1:77,000-1:34,000 live births. The disease demonstrates maternal, X-linked, and autosomal recessive inheritance.
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24
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Baden KN, Murray J, Capaldi RA, Guillemin K. Early Developmental Pathology Due to Cytochrome c Oxidase Deficiency Is Revealed by a New Zebrafish Model. J Biol Chem 2007; 282:34839-49. [PMID: 17761683 DOI: 10.1074/jbc.m703528200] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Deficiency of cytochrome c oxidase (COX) is associated with significant pathology in humans. However, the consequences for organogenesis and early development are not well understood. We have investigated these issues using a zebrafish model. COX deficiency was induced using morpholinos to reduce expression of CoxVa, a structural subunit, and Surf1, an assembly factor, both of which impaired COX assembly. Reduction of COX activity to 50% resulted in developmental defects in endodermal tissue, cardiac function, and swimming behavior. Cellular investigations revealed different underlying mechanisms. Apoptosis was dramatically increased in the hindbrain and neural tube, and secondary motor neurons were absent or abnormal, explaining the motility defect. In contrast, the heart lacked apoptotic cells but showed increasingly poor performance over time, consistent with energy deficiency. The zebrafish model has revealed tissue-specific responses to COX deficiency and holds promise for discovery of new therapies to treat mitochondrial diseases in humans.
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Affiliation(s)
- Katrina N Baden
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon 97403-1229, USA
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25
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Pronicki M, Matyja E, Piekutowska-Abramczuk D, Szymanska-Debinska T, Karkucinska-Wieckowska A, Karczmarewicz E, Grajkowska W, Kmiec T, Popowska E, Sykut-Cegielska J. Light and electron microscopy characteristics of the muscle of patients with SURF1 gene mutations associated with Leigh disease. J Clin Pathol 2007; 61:460-6. [PMID: 17908801 PMCID: PMC2571978 DOI: 10.1136/jcp.2007.051060] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
AIMS Leigh syndrome (LS) is characterised by almost identical brain changes despite considerable causal heterogeneity. SURF1 gene mutations are among the most frequent causes of LS. Although deficiency of cytochrome c oxidase (COX) is a typical feature of the muscle in SURF1-deficient LS, other abnormalities have been rarely described. The aim of the present work is to assess the skeletal muscle morphology coexisting with SURF1 mutations from our own research and in the literature. METHODS Muscle samples from 21 patients who fulfilled the criteria of LS and SURF1 mutations (14 homozygotes and 7 heterozygotes of c.841delCT) were examined by light and electron microscopy. RESULTS Diffuse decreased activity or total deficit of COX was revealed histochemically in all examined muscles. No ragged red fibres (RRFs) were seen. Lipid accumulation and fibre size variability were found in 14 and 9 specimens, respectively. Ultrastructural assessment showed several mitochondrial abnormalities, lipid deposits, myofibrillar disorganisation and other minor changes. In five cases no ultrastructural changes were found. Apart from slight correlation between lipid accumulation shown by histochemical and ultrastructural techniques, no other correlations were revealed between parameters investigated, especially between severity of morphological changes and the patient's age at the biopsy. CONCLUSION Histological and histochemical features of muscle of genetically homogenous SURF1-deficient LS were reproducible in detection of COX deficit. Minor muscle changes were not commonly present. Also, ultrastructural abnormalities were not a consistent feature. It should be emphasised that SURF1-deficient muscle assessed in the light and electron microscopy panel may be interpreted as normal if COX staining is not employed.
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Affiliation(s)
- M Pronicki
- Department of Pathology, The Children's Memorial Health Institute, Warsaw, Poland.
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26
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Pancrudo J, Shanske S, Bonilla E, Daras M, Akman HO, Krishna S, Malkin E, DiMauro S. Mitochondrial encephalomyopathy due to a novel mutation in the tRNAGlu of mitochondrial DNA. J Child Neurol 2007; 22:858-62. [PMID: 17715279 DOI: 10.1177/0883073807304199] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
A 14-year-old boy had exercise intolerance, weakness, ataxia, and lactic acidosis. Because his muscle biopsy showed a mosaic pattern of fibers staining intensely with the succinate dehydrogenase reaction but not at all with the cytochrome c oxidase reaction, we sequenced his mitochondrial DNA and found a novel mutation (C14680A) in the gene for tRNAGlu. The mutation was present in accessible tissues from the asymptomatic mother but not from a brother with Asperger syndrome. These data expand the clinical heterogeneity of mutations in this mitochondrial gene.
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Affiliation(s)
- Jacklyn Pancrudo
- H. Houston Merritt Clinical Research Center for Muscular Dystrophy and Related Diseases, Department of Neurology, 4-420 College of Physicians and Surgeons, Columbia University Medical Center, 630 W. 168th Street, New York, NY 10032, USA
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27
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Zhang Y, Yang YL, Sun F, Cai X, Qian N, Yuan Y, Wang ZX, Qi Y, Xiao JX, Wang XY, Zhang YH, Jiang YW, Qin J, Wu XR. Clinical and molecular survey in 124 Chinese patients with Leigh or Leigh-like syndrome. J Inherit Metab Dis 2007; 30:265. [PMID: 17323145 DOI: 10.1007/s10545-006-0481-y] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2006] [Revised: 12/06/2006] [Accepted: 12/11/2006] [Indexed: 10/23/2022]
Abstract
Leigh syndrome is the most common mitochondrial disorder in children characterized by necrotic lesions in the central nervous system. Both mitochondrial DNA (mtDNA) and nuclear DNA defects in the mitochondrial respiratory chain can lead to this disease. To characterize the clinical and genetic traits of Leigh or Leigh-like syndrome patients in China, 124 unrelated cases were collected between 1992 and 2005. Seventy-seven cases (62.1%) met the typical criteria of Leigh syndrome, including symmetrical bilateral abnormal signals in the basal ganglia, thalamus and brain stem, etc. Other cases (37.9%) belonged to Leigh-like syndrome with atypical clinical or radiological manifestations. Late-onset patients accounted for 20.2%, which is more than previously reported. Movement disorder was the most common symptoms in our patients. Thirty-two patients (25.8%) were confirmed to carry mutant genes. Among them, six cases (4.8%) have been demonstrated to have point mutations in mitochondrial DNA. Two separate patients were detected to have mutations on A8344G and A3243G. The T8993G point mutation was identified in one patient and T8993C in one other patient. SURF1 mutations associated with cytochrome-c oxidase deficiency were identified in 25 patients (20.2%). Four unreported variations have been identified in SURF1 gene from three patients. G604C was found in 22 patients. Only one patient had C214T mutation in the pyruvate dehydrogenase E1alpha subunit gene. In the remaining 92 patients (74.2%), a specific molecular dysfunction or underlying metabolic abnormality could not be identified.
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Affiliation(s)
- Y Zhang
- Department of Pediatrics, Peking University First Hospital, Beijing, PR China
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28
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Abstract
The biogenesis of the inner mitochondrial membrane enzyme cytochrome c oxidase (COX) is a complex process that requires the actions of ancillary proteins, collectively called assembly factors. Studies with the yeast Saccharomyces cerevisiae have provided considerable insight into the COX assembly pathway and have proven to be a fruitful model for understanding the molecular bases for inherited COX deficiencies in humans. In this review, we focus on critical steps in the COX assembly pathway. These processes are conserved from yeast to humans and are known to be involved in the etiology of human COX deficiencies. The contributions from our studies in yeast suggest that this organism remains an excellent model system for delineating the molecular mechanisms underlying COX assembly defects in humans. Current progress suggests that a complete picture of COX assembly will be achieved in the near future.
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Affiliation(s)
- Jennifer M Zee
- Department of Medical Genetics, University of Alberta, Edmonton, AB T6G 0M2, Canada
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29
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van Dijk ADJ, Ciofi-Baffoni S, Banci L, Bertini I, Boelens R, Bonvin AMJJ. Modeling protein-protein complexes involved in the cytochrome C oxidase copper-delivery pathway. J Proteome Res 2007; 6:1530-9. [PMID: 17338559 DOI: 10.1021/pr060651f] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Proper assembly and function of cytochrome c oxidase, which catalyzes the reduction of O2 and generates the proton gradient driving ATP synthesis, depend on correct copper delivery and incorporation. Structural details about the protein-protein complexes involved in this process are still missing. We describe here models of four complexes along this pathway obtained by combining bioinformatics interface predictions with information-driven docking and discuss their relevance with respect to known and pathogenic mutations.
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Affiliation(s)
- Aalt D J van Dijk
- Bijvoet Center for Biomolecular Research, Science Faculty, Utrecht University, 3584CH, Utrecht, The Netherlands
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30
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Knuf M, Faber J, Huth RG, Freisinger P, Zepp F, Kampmann C. Identification of a novel compound heterozygote SCO2 mutation in cytochrome c oxidase deficient fatal infantile cardioencephalomyopathy. Acta Paediatr 2007; 96:130-2. [PMID: 17187620 DOI: 10.1111/j.1651-2227.2007.00008.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
UNLABELLED Fatal infantile cardioencephalomyopathy (OMIM No. 604377) is a disorder of the mitochondrial respiratory chain and is characterised by neonatal progressive muscular hypotonia and cardiomyopathy because of severe Cytochrome c oxidase deficiency. Here we report a novel mutation in the Cytochrome c oxidase assembly gene SCO2 in an infant with fatal infantile cardioencephalomyopathy despite normal initial metabolic screening. CONCLUSION In newborns with unexplained muscular hypotonia and cardiomyopathy genetic testing of mitochondrial respiratory chain disorders might be helpful to establish a final diagnosis and guide treatment decisions.
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Affiliation(s)
- M Knuf
- Children's Hospital, Johannes Gutenberg-University, Mainz, Germany
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31
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Fernandez-Vizarra E, Berardinelli A, Valente L, Tiranti V, Zeviani M. Nonsense mutation in pseudouridylate synthase 1 (PUS1) in two brothers affected by myopathy, lactic acidosis and sideroblastic anaemia (MLASA). J Med Genet 2006; 44:173-80. [PMID: 17056637 PMCID: PMC2598032 DOI: 10.1136/jmg.2006.045252] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
INTRODUCTION Myopathy, lactic acidosis and sideroblastic anaemia (MLASA) is a rare condition that combines early-onset myopathy with lactic acidosis and sideroblastic anaemia. MLASA has been associated with a missense mutation in pseudouridylate synthase 1 (PUS1), an enzyme located in both nucleus and mitochondria, which converts uridine into pseudouridine in several cytosolic and mitochondrial tRNA positions and increases the efficiency of protein synthesis in both compartments. SUBJECTS AND METHODS We have identified two Italian brothers, offspring of distantly related parents, both of whom are affected by MLASA. The six exons of the PUS1 gene were analysed by automated sequencing. RESULTS We found combined defects in mitochondrial respiratory chain complexes in muscle and fibroblast homogenates of both patients, and low levels of mtDNA translation products in fibroblast mitochondria. A novel, homozygous stop mutation was present in PUS1 (E220X). We have investigated the structural and mechanistic aspects of the double localisation of PUS1, demonstrating that the isoform located in the nucleus contains an N-terminal extension which is absent in the mature mitochondrial isoform. CONCLUSIONS The stop mutation in PUS1 is likely to determine the loss of function of the protein, since it predicts the synthesis of a protein missing 208/427 amino acid residues on the C terminus, and was associated with low mtDNA translation. The structural differences in nuclear versus mitochondrial isoforms of PUS1 may be implicated in the variability of the clinical presentations in MLASA.
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MESH Headings
- Acidosis, Lactic/enzymology
- Acidosis, Lactic/genetics
- Amino Acid Sequence
- Anemia, Sideroblastic/enzymology
- Anemia, Sideroblastic/genetics
- Cell Nucleus/enzymology
- Codon, Nonsense
- Consanguinity
- Cytochrome-c Oxidase Deficiency/genetics
- Electron Transport Complex I/deficiency
- Fatal Outcome
- Fibroblasts/enzymology
- Fibroblasts/pathology
- HeLa Cells
- Human Growth Hormone/deficiency
- Humans
- Hydro-Lyases/chemistry
- Hydro-Lyases/deficiency
- Hydro-Lyases/genetics
- Infant, Newborn
- Intellectual Disability/genetics
- Male
- Mitochondria, Muscle/enzymology
- Mitochondrial Myopathies/enzymology
- Mitochondrial Myopathies/genetics
- Molecular Sequence Data
- Muscle, Skeletal/enzymology
- Muscle, Skeletal/pathology
- Phenotype
- Protein Isoforms/analysis
- Protein Isoforms/genetics
- Protein Precursors/metabolism
- Protein Processing, Post-Translational
- Protein Transport/drug effects
- Syndrome
- Transcription, Genetic
- Transfection
- Valinomycin/pharmacology
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Affiliation(s)
- Erika Fernandez-Vizarra
- Division of Molecular Neurogenetics, Pierfranco and Luisa Mariani Center for the Study of Mitochondrial Disorders of Infancy and Childhood, National Institute of Neurology C. Besta, Milan, Italy
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Abstract
Alexander disease is a neurodegenerative disorder characterized by macrocephaly and progressive demyelination with frontal lobe preponderance. The infantile form, the most frequent variant, appears between birth and 2 years of age and involves a severe course with a rapid neurologic deterioration. Although magnetic resonance imaging is useful for diagnosis, currently diagnosis is confirmed by the finding of missense mutation in the glial fibrillary acidic protein (GFAP) gene. This case reports a female who presented at the age of 5 months with refractory epilepsy and hypotonia. Laboratory examinations, muscle biopsy examination, and energetic metabolic study in muscle indicated increased concentrations of lactate, mitochondria with structural abnormalities, and decreased cytochrome-c oxidase activity respectively. Later, both clinical course and magnetic resonance findings were compatible with Alexander disease, which was confirmed by the finding of a novel glial fibrillary acidic protein gene mutation.
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Affiliation(s)
- Cristina Cáceres-Marzal
- Unit of Child Neurology, Department of Pediatrics, Hospital Materno-Infantil, Badajoz, Spain.
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Matthes T, Rustin P, Trachsel H, Darbellay R, Costaridou S, Xaidara A, Rideau A, Beris P. Different pathophysiological mechanisms of intramitochondrial iron accumulation in acquired and congenital sideroblastic anemia caused by mitochondrial DNA deletion. Eur J Haematol 2006; 77:169-74. [PMID: 16856911 DOI: 10.1111/j.1600-0609.2006.00674.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Sideroblastic anemias (SA) are characterized by iron accumulation in the mitochondria of erythroblasts. Although we have evidence of mitochondrial gene alterations in sporadic congenital cases, the origin of acquired forms [refractory anemia with ring sideroblasts (RARS)], is still largely unknown. Here, we report the analysis of respiratory chain function in a patient with a large mitochondrial deletion and in patients with RARS. A young boy with SA showed symptoms typical of a mitochondrial disease with metabolic acidosis, muscle weakness and cerebral involvement. His bone marrow DNA was analyzed for the presence of mitochondrial deletions. We found a new mitochondrial (mt)DNA deletion spanning 3,614 bp and including all the mt genes encoding complex IV, plus ATPase 6 and 8, and several transfer (t)RNAs. All tissues analyzed (liver, skeletal muscle, brain, pancreas) showed a heteroplasmic distribution of this mutant DNA. Bone marrow homogenates were obtained from five patients with RARS and from three patients with normal bone marrow and respiratory chain function assayed by spectrophotometric analysis. Cytochrome c oxidase (CCO) activity was greatly reduced in the patient's bone marrow. In contrast, CCO activity and global respiratory chain function were conserved in patients with RARS. We conclude that deficient CCO activity secondary to mtDNA deletions is related to intramitochondrial iron accumulation, as in our patient or in those with Pearson's syndrome, whereas other mechanisms, e.g. nuclear DNA mutations, have to be proposed to be involved in the acquired forms of SA.
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Affiliation(s)
- Thomas Matthes
- Department of Internal Medicine, Unit of Clinical Hematology, University Hospital, Geneva, Switzerland.
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Pye D, Kyriakouli DS, Taylor GA, Johnson R, Elstner M, Meunier B, Chrzanowska-Lightowlers ZMA, Taylor RW, Turnbull DM, Lightowlers RN. Production of transmitochondrial cybrids containing naturally occurring pathogenic mtDNA variants. Nucleic Acids Res 2006; 34:e95. [PMID: 16885236 PMCID: PMC1540737 DOI: 10.1093/nar/gkl516] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The human mitochondrial genome (mtDNA) encodes polypeptides that are critical for coupling oxidative phosphorylation. Our detailed understanding of the molecular processes that mediate mitochondrial gene expression and the structure–function relationships of the OXPHOS components could be greatly improved if we were able to transfect mitochondria and manipulate mtDNA in vivo. Increasing our knowledge of this process is not merely of fundamental importance, as mutations of the mitochondrial genome are known to cause a spectrum of clinical disorders and have been implicated in more common neurodegenerative disease and the ageing process. In organellar or in vitro reconstitution studies have identified many factors central to the mechanisms of mitochondrial gene expression, but being able to investigate the molecular aetiology of a limited number of cell lines from patients harbouring mutated mtDNA has been enormously beneficial. In the absence of a mechanism for manipulating mtDNA, a much larger pool of pathogenic mtDNA mutations would increase our knowledge of mitochondrial gene expression. Colonic crypts from ageing individuals harbour mutated mtDNA. Here we show that by generating cytoplasts from colonocytes, standard fusion techniques can be used to transfer mtDNA into rapidly dividing immortalized cells and, thereby, respiratory-deficient transmitochondrial cybrids can be isolated. A simple screen identified clones that carried putative pathogenic mutations in MTRNR1, MTRNR2, MTCOI and MTND2, MTND4 and MTND6. This method can therefore be exploited to produce a library of cell lines carrying pathogenic human mtDNA for further study.
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Affiliation(s)
| | | | | | | | | | - Brigitte Meunier
- Centre de Génétique Moléculaire, CNRSAvenue de la Terrasse, 91198 Gif-sur-Yvette, France
| | | | | | | | - Robert N. Lightowlers
- To whom correspondence should be addressed. Tel: +44 191 222 8028; Fax: +44 191 222 8553;
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Yüksel A, Seven M, Cetincelik U, Yeşil G, Köksal V. Facial dysmorphism in Leigh syndrome with SURF-1 mutation and COX deficiency. Pediatr Neurol 2006; 34:486-9. [PMID: 16765830 DOI: 10.1016/j.pediatrneurol.2005.10.020] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/16/2005] [Revised: 09/20/2005] [Accepted: 10/31/2005] [Indexed: 11/19/2022]
Abstract
Leigh syndrome is an inherited, progressive neurodegenerative disorder of infancy and childhood. Mutations in the nuclear SURF-1 gene are specifically associated with cytochrome C oxidase-deficient Leigh syndrome. This report describes two patients with similar facial features. One of them was a 2(1/2)-year-old male, and the other was a 3-year-old male with a mutation in SURF-1 gene and facial dysmorphism including frontal bossing, brachycephaly, hypertrichosis, lateral displacement of inner canthi, esotropia, maxillary hypoplasia, hypertrophic gums, irregularly placed teeth, upturned nostril, low-set big ears, and retrognathi. The first patient's magnetic resonance imaging at 15 months of age indicated mild symmetric T2 prolongation involving the subthalamic nuclei. His second magnetic resonance imaging at 2 years old revealed a symmetric T2 prolongation involving the subthalamic nuclei, substantia nigra, and medulla lesions. In the second child, at the age of 2 the first magnetic resonance imaging documented heavy brainstem and subthalamic nuclei involvement. A second magnetic resonance imaging, performed when he was 3 years old, revealed diffuse involvement of the substantia nigra and hyperintense lesions of the central tegmental tract in addition to previous lesions. Facial dysmorphism and magnetic resonance imaging findings, observed in these cases, can be specific findings in Leigh syndrome patients with cytochrome C oxidase deficiency. SURF-1 gene mutations must be particularly reviewed in such patients.
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Affiliation(s)
- Adnan Yüksel
- Department of Medical Genetic, Division of Pediatric Neurology, Cerrahpaşa Medical Faculty, Istanbul University, Turkey.
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36
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Coenen MJH, Smeitink JAM, Pots JM, van Kaauwen E, Trijbels FJM, Hol FA, van den Heuvel LP. Sequence analysis of the structural nuclear encoded subunits and assembly genes of cytochrome c oxidase in a cohort of 10 isolated complex IV-deficient patients revealed five mutations. J Child Neurol 2006; 21:508-11. [PMID: 16948936 DOI: 10.1177/08830738060210062501] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The mitochondrial oxidative phosphorylation system is composed of five multiprotein complexes. The fourth complex of this system, cytochrome c oxidase (complex IV), consists of 13 subunits: 3 encoded by mitochondrial DNA and 10 encoded by the nuclear genome. Patients with an isolated complex IV deficiency frequently harbor mutations in nuclear genes encoding for proteins necessary for the assembly of the complex. Strikingly, until now, no mutations have been detected in the nuclear encoded structural subunits of complex IV in these patients. We report the results of a mutational analysis study in patients with isolated complex IV deficiency screened for mutations in all structural genes as well as assembly genes known to cause complex IV deficiency. Four patients carried mutations in the complex IV assembly gene SURF1. One patient harbored a mutation in the COX10 gene involved in heme A synthesis. Mutations in the 10 nuclear encoded structural genes were not present.
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Affiliation(s)
- Marieke J H Coenen
- Department of Paediatrics, Nijmegen Centre for Mitochondrial Disorders, Radboud University Nijmegen Medical Centre, 6500 HB Nijmegen, the Netherlands
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Bugiani M, Tiranti V, Farina L, Uziel G, Zeviani M. Novel mutations in COX15 in a long surviving Leigh syndrome patient with cytochrome c oxidase deficiency. J Med Genet 2006; 42:e28. [PMID: 15863660 PMCID: PMC1736058 DOI: 10.1136/jmg.2004.029926] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
BACKGROUND Isolated cytochrome c oxidase (COX) deficiency is usually associated with mutations in several factors involved in the biogenesis of COX. METHODS We describe a patient with atypical, long surviving Leigh syndrome carrying two novel mutations in the COX15 gene, which encodes an enzyme involved in the biosynthesis of heme A. RESULTS Only two COX15 mutated patients, one with severe neonatal cardiomyopathy, the other with rapidly fatal Leigh syndrome, have been described to date. In contrast, our patient had a slowly progressive course with no heart involvement. COX deficiency was mild in muscle and a normal amount of fully assembled COX was present in cultured fibroblasts. CONCLUSIONS The clinical and biochemical phenotypes in COX15 defects are more heterogeneous than in other conditions associated with COX deficiency, such as mutations in SURF1.
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Affiliation(s)
- M Bugiani
- Department of Child Neurology, Istituto Nazionale Neurologico C. Besta, Milan, Italy
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38
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van Riesen AKJ, Antonicka H, Ohlenbusch A, Shoubridge EA, Wilichowski EKG. Maternal segmental disomy in Leigh syndrome with cytochrome c oxidase deficiency caused by homozygous SURF1 mutation. Neuropediatrics 2006; 37:88-94. [PMID: 16773507 DOI: 10.1055/s-2006-924227] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Cytochrome c oxidase deficiency (COX) is the most frequent cause of Leigh syndrome (LS), a mitochondrial subacute necrotizing encephalomyelopathy. Most of these LS (COX-) patients show mutations in SURF1 on chromosome 9 (9q34), which encodes a protein essential for the assembly of the COX complex. We describe a family whose first-born boy developed characteristic features of LS. Severe COX deficiency in muscle was caused by a novel homozygous nonsense mutation in SURF1. Segregation analysis of this mutation in the family was incompatible with autosomal recessive inheritance but consistent with a maternal disomy. Haplotype analysis of microsatellite markers confirmed isodisomy involving nearly the complete long arm of chromosome 9 (9q21-9tel). No additional physical abnormalities were present in the boy, suggesting that there are no imprinted genes on the long arm of chromosome 9 which are crucial for developmental processes. This case of segmental isodisomy illustrates that genotyping of parents is crucial for correct genetic counseling.
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Affiliation(s)
- A K J van Riesen
- Department of Pediatrics and Pediatric Neurology, Georg August University Goettingen, Robert-Koch-Strasse 40, 37075 Goettingen, Germany.
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Yang YL, Sun F, Zhang Y, Qian N, Yuan Y, Wang ZX, Qi Y, Xiao JX, Wang XY, Qi ZY, Zhang YH, Jiang YW, Bao XH, Qin J, Wu XR. Clinical and laboratory survey of 65 Chinese patients with Leigh syndrome. Chin Med J (Engl) 2006; 119:373-7. [PMID: 16542579] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/07/2023] Open
Abstract
BACKGROUND Leigh syndrome is an inherited neurodegenerative disease that emerges in infancy and childhood and presents with a clinically heterogeneous variety of neuromuscular and non-neuromuscular disorders. It can result from the inheritance of mutations in either nuclear or mitochondrial DNA. In the current study, we performed a retrospective study in 65 patients in order to investigate the clinical and genetic characteristics of Leigh syndrome in Chinese patients. METHODS Sixty-five unrelated cases (35 men and 30 women) who were hospitalized in the past 12 years were reviewed. Diagnosis was based on both the clinical presentation and the characteristic neuropathologic findings of bilateral symmetric necrotizing lesions in the basal ganglia and brain stem as detected using cranial computed tomography (CT) scan or magnetic resonance imaging (MRI). The differential diagnosis of organic acidurias and fatty acid beta-oxidation defects were performed. Specific point mutations and deletions in mitochondrial DNA (T8993G, T8993C, T9176C, A8344G, A3243G) were screened by PCR-restriction analysis and Southern blot. The SURF1 gene was sequenced. Skeletal muscle biopsies were performed in 17 (26.2%) of the patients. The diagnosis was confirmed by autopsy in 6 (9.2%) patients. RESULTS The patients had various forms of metabolic encephalomyopathy. Fifty-nine (90.8%) of the patients had the typical neuroradiological features of Leigh syndrome, including symmetrical necrotizing lesions scattered within the basal ganglia, thalamus and brain stem. Twenty (30.8%) patients were confirmed by genetic, biochemical analysis and autopsy. Specific point mutations in mitochondrial DNA were found in 5 cases (7.7%). Of these, the A8344G mutation was detected in 2 patients. The T8993G, T8993C, and A3243G point mutations were identified in 3 other patients, respectively. SURF1 mutations associated with cytochrome c oxidase deficiency were identified in 8 (12.3%) families by DNA sequencing. A G604C mutation was identified in 6 (9.2%) patients. The genotypes of 52 patients remained unknown. CONCLUSIONS Leigh syndrome presents as a diverse array of clinical features and can result from specific mutations in nuclear or mitochondrial DNA. In this study, SURF1 mutations associated with cytochrome c oxidase deficiency were identified in 8 (12.3%) out of 65 patients with Leigh syndrome. It indicates that SURF1 mutations might be a common cause of Leigh syndrome in China. The etiology of Leigh syndrome in Chinese patients represents a persistent challenge to clinicians.
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Affiliation(s)
- Yan-ling Yang
- Department of Pediatrics, Peking University First Hospital, Beijing 100034, China.
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40
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Coenen MJH, Smeitink JAM, Farhoud MH, Nijtmans LGJ, Rodenburg R, Janssen A, van Kaauwen EPM, Trijbels FJM, van den Heuvel LP. The first patient diagnosed with cytochrome c oxidase deficient Leigh syndrome: progress report. J Inherit Metab Dis 2006; 29:212-3. [PMID: 16601896 DOI: 10.1007/s10545-006-0185-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Mutations in SURF1, an assembly gene for cytochrome c oxidase (COX), the fourth complex of the oxidative phosphorylation system, are most frequently encountered in patients with COX deficiency. We describe a patient with Leigh syndrome harbouring a mutation in SURF1 who was reported decades ago with a tissue-specific cytochrome c oxidase deficiency.
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Affiliation(s)
- M J H Coenen
- Nijmegen Centre for Mitochondrial Disorder, Radboud University Nijmegen Medical Centre, The Netherlands
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Böhm M, Pronicka E, Karczmarewicz E, Pronicki M, Piekutowska-Abramczuk D, Sykut-Cegielska J, Mierzewska H, Hansikova H, Vesela K, Tesarova M, Houstkova H, Houstek J, Zeman J. Retrospective, multicentric study of 180 children with cytochrome C oxidase deficiency. Pediatr Res 2006; 59:21-6. [PMID: 16326995 DOI: 10.1203/01.pdr.0000190572.68191.13] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
A retrospective, multicenter study of 180 children with cytochrome c oxidase (COX) deficiency analyzed the clinical features, prognosis, and molecular bases of the COX deficiency. Clinical symptoms including failure to thrive, encephalopathy, hypotony, Leigh syndrome, cardiac involvement, and hepatopathy appeared in most patients early after birth or in early childhood. Two thirds of all children died. Biochemical examination revealed an isolated COX deficiency in 101 children and COX deficiency combined with disturbances of other respiratory chain complexes in 79 children. Blood and cerebrospinal fluid lactate increased in 85% and 81% of examined cases, respectively. Pathogenic mutations in mitochondrial or nuclear DNA were established in 75 patients. Mutations in surfeit locus protein 1 gene (SURF1) were found in 47 children with Leigh syndrome; 2bp deletion 845-846delCT was found in 89% of independent alleles. Mutations in a mitochondrial copper-binding protein (SCO2) gene were found in nine children with encephalomyopathy and/or cardiomyopathy; all of them were homozygotes or heterozygotes for 1541G>A mutation. Different mitochondrial DNA (mtDNA) deletion or depletion were found in nine children, mtDNA mutation 3243A>G in six, mtDNA mutation 8363G>A in two children with Leigh syndrome and mtDNA mutations 8344A>G, and 9205-9206delTA in one child each. COX deficiency represents a heterogeneous group of diseases with unfavorable prognosis. Marked prevalence of two nuclear DNA mutations (845-846delCT in the SURF1 gene and 1541G>A in the SCO2 gene) associated with COX deficiency in a Slavonic population suggests the existence of regional differences in the genetic basis of COX deficiency.
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Affiliation(s)
- Marek Böhm
- Department of Pediatrics, Faculty of Medicine, Charles University, Prague, Czech Republic
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42
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Monnot S, Chabrol B, Cano A, Pellissier JF, Collignon P, Montfort MF, Paquis-Flucklinger V. [Cytochrome c oxydase-deficient Leigh syndrome with homozygous mutation in SURF1 gene]. Arch Pediatr 2005; 12:568-71. [PMID: 15885549 DOI: 10.1016/j.arcped.2005.01.019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2004] [Accepted: 01/25/2005] [Indexed: 11/27/2022]
Abstract
Leigh syndrome is a heterogeneous disorder, usually due to a defect in oxidative metabolism. Mutations in SURF1 gene have been identified in patients with cytochrome c oxidase deficiency. We report a homozygous splice site deletion [516-2_516-1delAG] in a young girl presenting with cytochrome c oxidase-deficient Leigh syndrome. Identification of molecular defect is indispensable for genetic counselling and prenatal diagnosis.
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Affiliation(s)
- S Monnot
- Service de génétique médicale, hôpital Archet 2, 151, route de Saint-Antoine-de-Ginestière, 06202 Nice cedex 03, France
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Diaz F, Thomas CK, Garcia S, Hernandez D, Moraes CT. Mice lacking COX10 in skeletal muscle recapitulate the phenotype of progressive mitochondrial myopathies associated with cytochrome c oxidase deficiency. Hum Mol Genet 2005; 14:2737-48. [PMID: 16103131 PMCID: PMC2778476 DOI: 10.1093/hmg/ddi307] [Citation(s) in RCA: 129] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We have created a mouse model with an isolated cytochrome c oxidase (COX) deficiency by disrupting the COX10 gene in skeletal muscle. Missense mutations in COX10 have been previously associated with mitochondrial disorders. Cox10p is a protoheme:heme-O-farnesyl transferase required for the synthesis of heme a, the prosthetic group of the catalytic center of COX. COX10 conditional knockout mice were generated by crossing a LoxP-tagged COX10 mouse with a transgenic mouse expressing cre recombinase under the myosin light chain 1f promoter. The COX10 knockout mice were healthy until approximately 3 months of age when they started developing a slowly progressive myopathy. Surprisingly, even though COX activity in COX10 KO muscles was <5% of control muscle at 2.5 months, these muscles were still able to contract at 80-100% of control maximal forces and showed only a 10% increase in fatigability, and no signs of oxidative damage or apoptosis were detected. However, the myopathy worsened with time, particularly in female animals. This COX10 KO mouse allowed us to correlate the muscle function with residual COX activity, an estimate that can help predict the progression pattern of human mitochondrial myopathies.
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Affiliation(s)
- Francisca Diaz
- Department of Neurology, University of Miami Miller School of Medicine, 1095 NW 14th Terrace, Miami, FL 33136, USA
| | - Christine K. Thomas
- Department of Neurological Surgery, The Miami Project to Cure Paralysis, University of Miami Miller School of Medicine, 1095 NW 14th Terrace, Miami, FL 33136, USA
- Department of Physiology and Biophysics, University of Miami Miller School of Medicine, 1095 NW 14th Terrace, Miami, FL 33136, USA
| | - Sofia Garcia
- Department of Neurology, University of Miami Miller School of Medicine, 1095 NW 14th Terrace, Miami, FL 33136, USA
| | - Dayami Hernandez
- Department of Neurology, University of Miami Miller School of Medicine, 1095 NW 14th Terrace, Miami, FL 33136, USA
| | - Carlos T. Moraes
- Department of Neurology, University of Miami Miller School of Medicine, 1095 NW 14th Terrace, Miami, FL 33136, USA
- Department of Cell Biology and Anatomy, University of Miami Miller School of Medicine, 1095 NW 14th Terrace, Miami, FL 33136, USA
- To whom correspondence should be addressed. Tel: +1 3052435858; Fax: +1 3052433914.
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Tay SKH, Sacconi S, Akman HO, Morales JF, Morales A, De Vivo DC, Shanske S, Bonilla E, DiMauro S. Unusual clinical presentations in four cases of Leigh disease, cytochrome C oxidase deficiency, and SURF1 gene mutations. J Child Neurol 2005; 20:670-4. [PMID: 16225813 DOI: 10.1177/08830738050200080701] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Mutations in the SURF1 gene are the most frequent causes of Leigh disease with cytochrome c oxidase deficiency. We describe four children with novel SURF1 mutations and unusual features: three had prominent renal symptoms and one had ragged red fibers in the muscle biopsy. We identified five pathogenic mutations in SURF1: two mutations were novel, an in-frame nonsense mutation (834G-->A) and an out-of-frame duplication (820-824dupTACAT). Although renal manifestations have not been described in association with SURF1 mutations, they can be part of the clinical presentation. Likewise, mitochondrial proliferation in muscle (with ragged red fibers) is most unusual in Leigh disease but might be part of an emerging phenotype.
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Affiliation(s)
- Stacey K H Tay
- Department of Neurology, Columbia University, New York, NY, USA
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Coulbault L, Herlicoviez D, Chapon F, Read MH, Penniello MJ, Reynier P, Fayet G, Lombès A, Jauzac P, Allouche S. A novel mutation in the mitochondrial tRNAAsn gene associated with a lethal disease. Biochem Biophys Res Commun 2005; 329:1152-4. [PMID: 15752774 DOI: 10.1016/j.bbrc.2005.02.083] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2005] [Indexed: 10/25/2022]
Abstract
We describe a lethal mitochondrial disease in a 10-month-old child who presented with encephalomyopathy. Histochemical and electron microscopy examinations of skeletal muscle biopsy revealed abnormal mitochondria associated with a combined deficiency of complexes I and IV. After excluding mitochondrial DNA deletions and depletion, direct sequencing was used to screen for mutation in all transfer RNA (tRNA) genes. A T-to-C substitution at position 5693 in the tRNA(Asn) gene was found in blood and muscle. Microdissection of muscle biopsy and its analysis revealed the highest level of this mutation in cytochrome c oxidase (COX)-negative fibres. We suggest that this novel mutation would affect the anticodon loop structure of the tRNA(Asn) and cause a fatal mitochondrial disease.
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Affiliation(s)
- Laurent Coulbault
- Laboratoire de Biochimie A, Centre Hospitalier et Universitaire de Caen, Avenue Côte de Nacre, 14033 Caen cedex, France
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Tay SKH, Nesti C, Mancuso M, Schon EA, Shanske S, Bonilla E, Davidson MM, Dimauro S. Studies of COX16, COX19, and PET191 in human cytochrome-c oxidase deficiency. ACTA ACUST UNITED AC 2005; 61:1935-7. [PMID: 15596615 DOI: 10.1001/archneur.61.12.1935] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
BACKGROUND Cytochrome-c oxidase (COX) is the terminal enzyme of the mitochondrial electron transport chain, and COX deficiency is a common cause of mitochondrial diseases. Cytochrome-c oxidase is composed of 13 subunits, of which 3 are encoded by mitochondrial DNA and 10 by nuclear DNA. Mutations have been identified in each of the 3 mitochondrial DNA genes but in none of the nuclear DNA genes. However, COX deficiency has been attributed to mutations in several nuclear DNA-encoded ancillary proteins needed for COX assembly and function. Despite this progress, the molecular basis of COX deficiency remains elusive in many patients, justifying the identification and screening of additional COX assembly genes, such as COX16, COX19, and PET191. OBJECTIVE To determine if COX16, COX19, and PET191 are implicated in human COX deficiency. METHODS Mutation screening was performed on 53 patients with isolated COX deficiency by direct sequencing of COX19 and by single-strand conformational polymorphism analysis for COX16 and PET191. RESULTS No mutations were found in COX16, COX19, or PET191 in these patients. CONCLUSIONS The COX16, COX19, and PET191 genes are either not involved or very rarely involved in human COX deficiency. Mutations in additional COX assembly genes remain to be identified.
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Affiliation(s)
- Stacey K H Tay
- Departments of Neurology, Genetics and Development, and Pathology, Columbia University College of Physicians and Surgeons, 630 W. 168th Street, New York, NY 10032, USA
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Vesela K, Hansikova H, Tesarova M, Martasek P, Elleder M, Houstek J, Zeman J. Clinical, biochemical and molecular analyses of six patients with isolated cytochrome c oxidase deficiency due to mutations in the SCO2 gene. Acta Paediatr 2005; 93:1312-7. [PMID: 15499950 DOI: 10.1080/08035250410008761] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 09/30/2022]
Abstract
BACKGROUND AND AIM Cytochrome c oxidase (COX) deficiency represents a heterogeneous group of disorders. Numerous proteins are required for efficient COX assembly and maintenance. In 26 children with isolated COX deficiency, we studied mutations in the SCO2 gene, which is involved in the copper transport into the inner mitochondrial membrane, and we analysed the clinical and biochemical consequences of SCO2 mutations. METHODS The activities of respiratory chain complexes were measured spectrophotometrically in isolated mitochondria and/or crude cell extracts in all available tissues. Two-dimensional polyacrylamide electrophoresis (2D-PAGE) was used to separate the complexes and their subunits. The mutations were detected by sequencing and RFLP analysis. RESULTS Mutations in the SCO2 gene were found in six children. Early neonatal onset of hypertrophic cardiomyopathy and encephalopathy were observed in one boy with compound heterozygous mutations C1280T and G1541A. In all five children with homozygous mutation G1541A, progressive encephalopathy developed between 2 and 6 mo of age. Isolated COX deficiency was found in the skeletal muscle, heart, liver and brain but not in fibroblasts. 2D-PAGE in the skeletal muscle showed markedly decreased amounts of all COX subunits. CONCLUSION Our results suggest that mutations in the SCO2 gene are not rare, at least in our population. Although clinical symptoms may rely on the type of SCO2 mutation, the prognosis is unfavourable in all patients.
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Affiliation(s)
- K Vesela
- Center of Integrated Genomics, Department of Paediatrics, Charles University Prague, Prague, Czech Republic
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48
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Oquendo CE, Antonicka H, Shoubridge EA, Reardon W, Brown GK. Functional and genetic studies demonstrate that mutation in the COX15 gene can cause Leigh syndrome. J Med Genet 2004; 41:540-4. [PMID: 15235026 PMCID: PMC1735852 DOI: 10.1136/jmg.2003.017426] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Abstract
Mitochondria are the central processing units for cellular energy metabolism and, in addition to carrying out oxidative phosphorylation, regulate important processes such as apoptosis and calcium homeostasis. Because mitochondria possess a genome that is central to their multiple functions, an understanding of the mechanism of mitochondrial gene expression is required to decipher the many ways mitochondrial dysfunction contributes to human disease. Towards this end, two human transcription factors that are related to rRNA methyltransferases have recently been characterized, providing new insight into the mechanism of mitochondrial transcription and a novel link to maternally inherited deafness. Furthermore, studies in the Saccharomyces cerevisiae model system have revealed a functional coupling of transcription and translation at the inner mitochondrial membrane, where assembly of the oxidative phosphorylation system commences. Defects in an analogous coupling mechanism in humans might underlie the cytochrome oxidase deficiency that causes a form of Leigh Syndrome.
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Affiliation(s)
- Gerald S Shadel
- Department of Pathology, Yale University School of Medicine, 300 Cedar Street, PO Box 208023, New Haven, CT 06520-8023, USA.
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Pecina P, Gnaiger E, Zeman J, Pronicka E, Houstek J. Decreased affinity for oxygen of cytochrome-coxidase in Leigh syndrome caused bySURF1mutations. Am J Physiol Cell Physiol 2004; 287:C1384-8. [PMID: 15269007 DOI: 10.1152/ajpcell.00286.2004] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Mutations in the gene SURF1 prevent synthesis of cytochrome- c oxidase (COX)-specific assembly protein and result in a fatal neurological disorder, Leigh syndrome. Because this severe COX deficiency presents with barely detectable changes of cellular respiratory rates under normoxic conditions, we analyzed the respiratory response to low oxygen in cultured fibroblasts harboring SURF1 mutations with high-resolution respirometry. The oxygen kinetics was quantified by the partial pressure of oxygen (Po2) at half-maximal respiration rate (P50) in intact coupled cells and in digitonin-permeabilized uncoupled cells. In both cases, the P50in patients was elevated 2.1- and 3.3-fold, respectively, indicating decreased affinity of COX for oxygen. These results suggest that at physiologically low intracellular Po2, the depressed oxygen affinity may lead in vivo to limitations of respiration, resulting in impaired energy provision in Leigh syndrome patients.
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Affiliation(s)
- Petr Pecina
- Institute of Physiology and Center for Integrated Genomics, Academy of Sciences of the Czech Republic, 142 20 Prague, Czech Republic
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