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Ayyub SA, Varshney U. Translation initiation in mammalian mitochondria- a prokaryotic perspective. RNA Biol 2019; 17:165-175. [PMID: 31696767 DOI: 10.1080/15476286.2019.1690099] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
Abstract
ATP is generated in mitochondria of eukaryotic cells by oxidative phosphorylation (OXPHOS). The OXPHOS complex, which is crucial for cellular metabolism, comprises of both nuclear and mitochondrially encoded subunits. Also, the occurrence of several pathologies because of mutations in the mitochondrial translation apparatus indicates the importance of mitochondrial translation and its regulation. The mitochondrial translation apparatus is similar to its prokaryotic counterpart due to a common origin of evolution. However, mitochondrial translation has diverged from prokaryotic translation in many ways by reductive evolution. In this review, we focus on mammalian mitochondrial translation initiation, a highly regulated step of translation, and present a comparison with prokaryotic translation.
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Affiliation(s)
- Shreya Ahana Ayyub
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, India
| | - Umesh Varshney
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, India.,Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, India
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Lim AZ, Blakely EL, Baty K, He L, Hopton S, Falkous G, McWilliam K, Cozens A, McFarland R, Taylor RW. A novel pathogenic m.4412G>A MT-TM mitochondrial DNA variant associated with childhood-onset seizures, myopathy and bilateral basal ganglia changes. Mitochondrion 2019; 47:18-23. [PMID: 31022467 PMCID: PMC6617384 DOI: 10.1016/j.mito.2019.04.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Revised: 04/18/2019] [Accepted: 04/19/2019] [Indexed: 12/03/2022]
Abstract
Mitochondrial DNA variants in the MT-TM (mt-tRNAMet) gene are rare, typically associated with myopathic phenotypes. We identified a novel MT-TM variant resulting in prolonged seizures with childhood-onset myopathy, retinopathy, short stature and elevated CSF lactate associated with bilateral basal ganglia changes on neuroimaging. Muscle biopsy confirmed multiple respiratory chain deficiencies and focal cytochrome c oxidase (COX) histochemical abnormalities. Next-generation sequencing of the mitochondrial genome revealed a novel m.4412G>A variant at high heteroplasmy levels in muscle that fulfils all accepted criteria for pathogenicity including segregation within single muscle fibres, thus broadening the genotypic and phenotypic landscape of mitochondrial tRNA-related disease.
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Affiliation(s)
- Albert Z Lim
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Emma L Blakely
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne NE2 4HH, UK; NHS Highly Specialised Service for Rare Mitochondrial Disorders of Adults and Children, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne NE2 4HH, UK
| | - Karen Baty
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne NE2 4HH, UK; NHS Highly Specialised Service for Rare Mitochondrial Disorders of Adults and Children, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne NE2 4HH, UK
| | - Langping He
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne NE2 4HH, UK; NHS Highly Specialised Service for Rare Mitochondrial Disorders of Adults and Children, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne NE2 4HH, UK
| | - Sila Hopton
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne NE2 4HH, UK; NHS Highly Specialised Service for Rare Mitochondrial Disorders of Adults and Children, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne NE2 4HH, UK
| | - Gavin Falkous
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne NE2 4HH, UK; NHS Highly Specialised Service for Rare Mitochondrial Disorders of Adults and Children, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne NE2 4HH, UK
| | - Kenneth McWilliam
- Department of Paediatric Neurology, Royal Hospital for Sick Children, Edinburgh EH9 1LF, UK
| | - Alison Cozens
- Inherited Metabolic Disorders Scotland, NHS National Services Scotland, Glasgow G2 6QE, UK
| | - Robert McFarland
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Robert W Taylor
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne NE2 4HH, UK; NHS Highly Specialised Service for Rare Mitochondrial Disorders of Adults and Children, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne NE2 4HH, UK.
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Kuwajima M, Goto M, Kurane K, Shimbo H, Omika N, Jimbo EF, Muramatsu K, Tajika M, Shimura M, Murayama K, Kurosawa K, Yamagata T, Osaka H. MELAS syndrome with m.4450 G > A mutation in mitochondrial tRNA Met gene. Brain Dev 2019; 41:465-469. [PMID: 30739820 DOI: 10.1016/j.braindev.2019.01.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Revised: 01/02/2019] [Accepted: 01/22/2019] [Indexed: 10/27/2022]
Abstract
Mutations in the mitochondrial tRNAMet gene have been reported in only five patients to date, all of whom presented with muscle weakness and exercise intolerance as signs of myopathy. We herein report the case of a 12-year-old girl with focal epilepsy since the age of eight years. At age 11, the patient developed sudden visual disturbances and headaches accompanied by recurrent, stroke-like episodes with lactic acidosis (pH 7.279, lactic acid 11.6 mmol/L). The patient frequently developed a delirious state, exhibited regression of intellectual ability. Brain magnetic resonance imaging revealed high-intensity signals on T2-weighted images of the left occipital lobe. Mitochondrial gene analysis revealed a heteroplasmic m.4450G > A mutation in the mitochondrial tRNAMet. The heteroplasmic rate of the m.4450G > A mutation in blood, skin, urinary sediment, hair, saliva, and nail samples were 20, 38, 59, 41, 27, and 35%, respectively. The patient's fibroblast showed an approximately 53% reduction in the oxygen consumption rate, compared to a control, and decreased complex I and IV activities. Stroke-like episodes, lactic acidosis, encephalopathy with brain magnetic resonance imaging findings, and declined mitochondrial function were consistent with mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) syndrome. To our knowledge, the findings associated with this first patient with MELAS syndrome harboring the m.4450G > A mutation in mitochondrial tRNAMet expand the phenotypic spectrum of tRNAMet gene.
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Affiliation(s)
- Mari Kuwajima
- Department of Pediatrics, Jichi Medical University, Japan
| | - Masahide Goto
- Department of Pediatrics, Jichi Medical University, Japan
| | - Koyuru Kurane
- Department of Pediatrics, Jichi Medical University, Japan
| | - Hiroko Shimbo
- Department of Genetics, Kanagawa Children's Medical Center, Yokohama, Kanagawa, Japan
| | - Narumi Omika
- Department of Pediatrics, Jichi Medical University, Japan
| | - Eriko F Jimbo
- Department of Pediatrics, Jichi Medical University, Japan
| | | | - Makiko Tajika
- Department of Metabolism, Chiba Children's Hospital, Japan
| | - Masaru Shimura
- Department of Metabolism, Chiba Children's Hospital, Japan
| | - Kei Murayama
- Department of Metabolism, Chiba Children's Hospital, Japan
| | - Kenji Kurosawa
- Department of Genetics, Kanagawa Children's Medical Center, Yokohama, Kanagawa, Japan
| | | | - Hitoshi Osaka
- Department of Pediatrics, Jichi Medical University, Japan.
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Finsterer J, Zarrouk-Mahjoub S. Modified Yarham and Smith scores for pathogenicity assessment of mtDNA tRNA variants. Neuromuscul Disord 2018; 28:373-374. [DOI: 10.1016/j.nmd.2018.01.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2017] [Accepted: 01/15/2018] [Indexed: 10/18/2022]
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Scarpelli M, Carreño-Gago L, Russignan A, de Luna N, Carnicer-Cáceres C, Ariatti A, Verriello L, Devigili G, Tonin P, Garcia-Arumi E, Pinós T. Identification and characterization of the novel m.8305C>T MTTK and m.4440G>A MTTM gene mutations causing mitochondrial myopathies. Neuromuscul Disord 2017; 28:137-143. [PMID: 29174468 DOI: 10.1016/j.nmd.2017.10.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Revised: 10/19/2017] [Accepted: 10/23/2017] [Indexed: 01/20/2023]
Abstract
We report on two novel mtDNA mutations in patients affected with mitochondrial myopathy. The first patient, a 44-year-old woman, had bilateral eyelid ptosis and the m.8305C>T mutation in the MTTK gene. The second patient, a 56-year-old man, had four-limb muscle weakness and the MTTM gene m.4440G>A mutation. Muscle biopsies in both patients showed ragged red fibers and numerous COX-negative fibers as well as a combined defect of complex I, III and IV activities. The two mutations were heteroplasmic and detected only in muscle tissue, with a higher mutation load in COX-negative fibers. Additionally, both mutations occurred in highly conserved mt-tRNA sites, and were not found by an in silico search in 30,589 human mtDNA sequences. Our report further expands the mutational and phenotypic spectrum of diseases associated with mutations in mitochondrial tRNA genes and reinforces the notion that mutations in mitochondrial tRNAs represent hot spots for mitochondrial myopathies in adults.
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Affiliation(s)
- Mauro Scarpelli
- Section of Neurology, Department of Neurological, Biomedical and Movement Sciences, University of Verona, Verona, Italy
| | - Lidia Carreño-Gago
- Mitochondrial Disorders Unit, Vall d'Hebron Institut de Recerca, Barcelona, Spain; Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain
| | - Anna Russignan
- Section of Neurology, Department of Neurological, Biomedical and Movement Sciences, University of Verona, Verona, Italy
| | - Noemi de Luna
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain; Laboratori de Malalties Neuromusculars, Institut de Recerca Hospital de la Santa Creu i Sant Pau, Universitat Autònoma de Barcelona, Spain
| | - Clara Carnicer-Cáceres
- Unidad de Metabolopatías, Servicio de Bioquímica, Hospital Universitari Vall d'Hebron, Barcelona, Spain
| | - Alessandra Ariatti
- Department of Neurosciences and Department of Onco-Haematology, University Hospitals of Modena & Reggio Emilia, Italy
| | - Lorenzo Verriello
- Division of Neurology, Department of Neuroscience, Azienda Ospedaliero Universitaria, Udine, Italy
| | - Grazia Devigili
- Division of Neurology, Department of Neuroscience, Azienda Ospedaliero Universitaria, Udine, Italy
| | - Paola Tonin
- Section of Neurology, Department of Neurological, Biomedical and Movement Sciences, University of Verona, Verona, Italy
| | - Elena Garcia-Arumi
- Mitochondrial Disorders Unit, Vall d'Hebron Institut de Recerca, Barcelona, Spain; Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain; Àrea de Genètica Clínica i Molecular, Hospital Universitari Vall d'Hebron, Barcelona, Spain.
| | - Tomàs Pinós
- Mitochondrial Disorders Unit, Vall d'Hebron Institut de Recerca, Barcelona, Spain; Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain.
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Darin N, Hedberg-Oldfors C, Kroksmark AK, Moslemi AR, Kollberg G, Oldfors A. Benign mitochondrial myopathy with exercise intolerance in a large multigeneration family due to a homoplasmic m.3250T>C mutation in MTTL1. Eur J Neurol 2017; 24:587-593. [PMID: 28181352 DOI: 10.1111/ene.13249] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2016] [Accepted: 01/04/2017] [Indexed: 11/26/2022]
Abstract
BACKGROUND AND PURPOSE Most mitochondrial disorders with onset in early childhood are progressive and involve multiple organs. The m.3250T>C mutation in MTTL1 has previously been described in a few individuals with a possibly riboflavin-responsive myopathy and an association with sudden infant death syndrome was suspected. We describe a large family with this mutation and evaluate the effect of riboflavin treatment. METHODS Medical data were collected with the help of a standardized data collection form. Sanger sequencing was used to screen for variants in mitochondrial DNA and the proportion of the mutation was analyzed in different tissues. Biochemical and muscle morphological investigations of muscle tissue were performed in two individuals. The effect of riboflavin treatment was evaluated in two individuals. RESULTS Thirteen family members experienced exercise intolerance with fatigue and weakness. Inheritance was maternal with 100% penetrance. The course was either static or showed improvement over time. There was no evidence of other organ involvement except for a possible mild transient cardiac enlargement in one child. Muscle investigations showed isolated complex I deficiency and mitochondrial proliferation. The level of m.3250T>C was apparently 100%, i.e. homoplasmic, in all examined tissues. Riboflavin treatment showed no effect in any treated family member and there have been no cases of sudden infant death in this family. CONCLUSIONS This study illustrates the importance of considering mitochondrial disorders in the work-up of individuals with exercise intolerance and provides a better understanding of the phenotype associated with the m.3250T>C mutation in MTTL1.
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Affiliation(s)
- N Darin
- Department of Pediatrics, Sahlgrenska University Hospital, University of Gothenburg, Gothenburg
| | - C Hedberg-Oldfors
- Department of Pathology and Genetics, Sahlgrenska University Hospital, University of Gothenburg, Gothenburg
| | - A-K Kroksmark
- Department of Pediatrics, Sahlgrenska University Hospital, University of Gothenburg, Gothenburg
| | - A-R Moslemi
- Department of Pathology and Genetics, Sahlgrenska University Hospital, University of Gothenburg, Gothenburg
| | - G Kollberg
- Department of Clinical Chemistry and Transfusion Medicine, Sahlgrenska University Hospital, University of Gothenburg, Gothenburg, Sweden
| | - A Oldfors
- Department of Pathology and Genetics, Sahlgrenska University Hospital, University of Gothenburg, Gothenburg
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