1
|
Ghirigato E, Terenzi F, Baglivo M, Zanetti N, Baldo F, Murru FM, Bobbo M, Barbi E, Zeviani M, Bruno I, Lamantea E. A new family with a case of severe early-onset muscle fatigue and a peculiar maternally inherited painful swelling in chewing muscles associated with homoplasmic m.15992A>T mutation in mitochondrial tRNA Pro. Neuromuscul Disord 2023; 33:972-977. [PMID: 38030461 DOI: 10.1016/j.nmd.2023.11.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Revised: 09/12/2023] [Accepted: 11/01/2023] [Indexed: 12/01/2023]
Abstract
A 16-year-old boy was evaluated for a history of exercise-induced fatigability associated with nausea even after minimal effort, lower limbs muscle hypotrophy, and swelling of the masseter muscles after chewing. Laboratory tests were remarkable for hyperlactatemia and metabolic acidosis after short physical activity. The muscle biopsy showed non-specific mitochondrial alterations and an increase in intrafibral lipids. Biochemical analysis showed reduced activity of the respiratory chain complexes. Mitochondrial DNA sequencing revealed the presence of a homoplasmic variant m.15992A>T in the MT-TP gene, coding for the mt-tRNAPro in the patient, in his mother and in his brother. Pathogenic or likely pathogenic variants in MT-TP gene are rare. They are responsible for different clinical presentation, almost ever involving the muscle tissue. We report the first family with exercise-induced muscle weakness and swelling of the chewing muscles due to m.15992A>T variant in absence of J1c10 haplogroup, confirming its pathogenicity.
Collapse
Affiliation(s)
| | | | - Mirko Baglivo
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Nadia Zanetti
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Francesco Baldo
- Institute for Maternal and Child Health IRCCS Burlo Garofolo, Trieste, Italy.
| | - Flora Maria Murru
- Institute for Maternal and Child Health IRCCS Burlo Garofolo, Trieste, Italy
| | - Marco Bobbo
- Institute for Maternal and Child Health IRCCS Burlo Garofolo, Trieste, Italy
| | - Egidio Barbi
- University of Trieste, Italy; Institute for Maternal and Child Health IRCCS Burlo Garofolo, Trieste, Italy
| | - Massimo Zeviani
- Institute for Maternal and Child Health IRCCS Burlo Garofolo, Trieste, Italy
| | - Irene Bruno
- Institute for Maternal and Child Health IRCCS Burlo Garofolo, Trieste, Italy
| | - Eleonora Lamantea
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| |
Collapse
|
2
|
The Mitochondrial tRNA Ser(UCN) Gene: A Novel m.7484A>G Mutation Associated with Mitochondrial Encephalomyopathy and Literature Review. Life (Basel) 2023; 13:life13020554. [PMID: 36836911 PMCID: PMC9963529 DOI: 10.3390/life13020554] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Revised: 01/26/2023] [Accepted: 02/14/2023] [Indexed: 02/18/2023] Open
Abstract
Mitochondrial tRNASer(UCN) is considered a hot-spot for non-syndromic and aminoglycoside-induced hearing loss. However, many patients have been described with more extensive neurological diseases, mainly including epilepsy, myoclonus, ataxia, and myopathy. We describe a novel homoplasmic m.7484A>G mutation in the tRNASer(UCN) gene affecting the third base of the anticodon triplet in a girl with profound intellectual disability, spastic tetraplegia, sensorineural hearing loss, a clinical history of epilepsia partialis continua and vomiting, typical of MELAS syndrome, leading to a myoclonic epilepticus status, and myopathy with severe COX deficiency at muscle biopsy. The mutation was also found in the homoplasmic condition in the mother who presented with mild cognitive deficit, cerebellar ataxia, myoclonic epilepsy, sensorineural hearing loss and myopathy with COX deficient ragged-red fibers consistent with MERRF syndrome. This is the first anticodon mutation in the tRNASer(UCN) and the second homoplasmic mutation in the anticodon triplet reported to date.
Collapse
|
3
|
The Evolutionary Dynamics of the Mitochondrial tRNA in the Cichlid Fish Family. BIOLOGY 2022; 11:biology11101522. [PMID: 36290425 PMCID: PMC9598224 DOI: 10.3390/biology11101522] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Revised: 03/05/2022] [Accepted: 03/08/2022] [Indexed: 11/06/2022]
Abstract
Simple Summary Cichlids are a unique example of fish diversity and species richness which have been explained by sympatric speciation at different freshwater sources in Africa. The mitochondria contribute to cell vitality by providing energy. It contains a circular genome with an established translation system that is spatially independent of the cytosolic counterpart. The current study aimed to investigate the evolutionary dynamics of the mitochondrial tRNA and its role in cichlids’ diversity. The available cichlid mitogenomes in the public database were filtered, in addition to newly sequenced accessions from a specific cichlid group known as the haplotilapiine lineage that is widely distributed in the Egyptian sector of the Nile River. Based on the comparative analysis of mitogenomic data, we identified 22 tRNA genes, in which a single gene was D-armless, while the cloverleaf secondary structure subdivided into stem-loop formations was predicted and used to define the levels of genetic divergence for the remained tRNAs. Peculiarly, in cichlids, the formation known as “T-arm” showed the lowest polymorphism levels among other structures in contrast to other organisms (e.g., scorpions). Comparing the whole family to the specific haplotilapiine lineage showed that the tryptophan tRNA was the most conserved tRNA, with signatures of possible purifying selection. Abstract The mitochondrial transfer RNA genes (tRNAs) attract more attention due to their highly dynamic and rapidly evolving nature. The current study aimed to detect and evaluate the dynamics, characteristic patterns, and variations of mitochondrial tRNAs. The study was conducted in two main parts: first, the published mitogenomic sequences of cichlids mt tRNAs have been filtered. Second, the filtered mitochondrial tRNA and additional new mitogenomes representing the most prevalent Egyptian tilapiine were compared and analyzed. Our results revealed that all 22 tRNAs of cichlids folded into a classical cloverleaf secondary structure with four domains, except for trnSGCU, missing the D domain in all cichlids. When consensus tRNAs were compared, most of the mutations were observed in the trnP at nucleotide levels (substitutions and indels), in contrast to trnLUAA. From a structural perspective, the anticodon loop and T-loop formations were the most conserved structures among all parts of the tRNA in contrast to the A-stem and D-loop formations. The trnW was the lowest polymorphic unneutral tRNA among all cichlids (both the family and the haplotilapiine lineage), in contrast with the neutral trnD that was extremely polymorphic among and within the haplotilapiine lineage species compared to other cichlids species. From a phylogenetic perspective, the trnC was extremely hypervariable and neutral tRNA in both haplotilapiine lineage and cichlids but was unable to report correct phylogenetic signal for the cichlids. In contrast to trnI and trnY, less variable neutral tRNAs that were able to cluster the haplotilapiine lineage and cichlids species as previously reported. By observing the DNA polymorphism in the coding DNA sequences (CDS), the highest affected amino acid by non-synonymous mutations was isoleucine and was equally mutated to valine and vice versa; no correlation between mutations in CDS and tRNAs was statistically found. The current study provides an insight into the mitochondrial tRNA evolution and its effect on the cichlid diversity and speciation model at the maternal level.
Collapse
|
4
|
Dogan SA, Giacchin G, Zito E, Viscomi C. Redox Signaling and Stress in Inherited Myopathies. Antioxid Redox Signal 2022; 37:301-323. [PMID: 35081731 DOI: 10.1089/ars.2021.0266] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Significance: Reactive oxygen species (ROS) are highly reactive compounds that behave like a double-edged sword; they damage cellular structures and act as second messengers in signal transduction. Mitochondria and endoplasmic reticulum (ER) are interconnected organelles with a central role in ROS production, detoxification, and oxidative stress response. Skeletal muscle is the most abundant tissue in mammals and one of the most metabolically active ones and thus relies mainly on oxidative phosphorylation (OxPhos) to synthesize adenosine triphosphate. The impairment of OxPhos leads to myopathy and increased ROS production, thus affecting both redox poise and signaling. In addition, ROS enter the ER and trigger ER stress and its maladaptive response, which also lead to a myopathic phenotype with mitochondrial involvement. Here, we review the role of ROS signaling in myopathies due to either mitochondrial or ER dysfunction. Recent Advances: Relevant advances have been evolving over the last 10 years on the intricate ROS-dependent pathways that act as modifiers of the disease course in several myopathies. To this end, pathways related to mitochondrial biogenesis, satellite cell differentiation, and ER stress have been studied extensively in myopathies. Critical Issues: The analysis of the chemistry and the exact quantitation, as well as the localization of ROS, are still challenging due to the intrinsic labile nature of ROS and the technical limitations of their sensors. Future Directions: The mechanistic studies of the pathogenesis of mitochondrial and ER-related myopathies offer a unique possibility to discover novel ROS-dependent pathways. Antioxid. Redox Signal. 37, 301-323.
Collapse
Affiliation(s)
- Sukru Anil Dogan
- Department of Molecular Biology and Genetics, Center for Life Sciences and Technologies, Bogazici University, Istanbul, Turkey
| | - Giacomo Giacchin
- Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Ester Zito
- Department of Biomolecular Sciences, University of Urbino Carlo Bo, Urbino, Italy.,Istituto di Ricerche Farmacologiche Mario Negri IRCCS, Milan, Italy
| | - Carlo Viscomi
- Department of Biomedical Sciences, University of Padova, Padova, Italy
| |
Collapse
|
5
|
Guo H, Guo L, Yuan Y, Liang XY, Bi R. Co-occurrence of m.15992A>G and m.15077G>A Is Associated With a High Penetrance of Maternally Inherited Hypertension in a Chinese Pedigree. Am J Hypertens 2022; 35:96-102. [PMID: 34346491 DOI: 10.1093/ajh/hpab123] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Revised: 07/25/2021] [Accepted: 08/03/2021] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Mitochondrial DNA (mtDNA) pathogenic variants have been identified to be associated with maternally inherited essential hypertension (MIEH). However, the distinctive clinical features and molecular pathogenesis of MIEH are not fully understood. METHODS In this study, we collected a Chinese MIEH family with extraordinary higher penetrance of essential hypertension (88.89%) and early ages of onset (31-40 years old), and performed clinical and genetic characterization for this family. The complete mitochondrial genome of the proband was sequenced and analyzed. RESULTS The maternally related members in this family were presented with severe increased blood pressure, left ventricular remodeling, and metabolic abnormalities. Through sequencing the entire mtDNA of the proband and performing systematic analysis of the mtDNA variants with a phylogenic approach, we identified a potentially pathogenic tRNA variant (m.15992A>G in the MT-TP gene) that may account for the MIEH in this family. One nonsynonymous variant (m.15077G>A in the MT-CYB gene) was identified to play a synergistic role with m.15992A>G to cause a high penetrance of MIEH. CONCLUSIONS Our results, together with previous findings, have indicated that tRNA pathogenic variants in the mtDNA could act important roles in the pathogenesis of MIEH through reducing mitochondrial translation and disturbing mitochondrial function.
Collapse
Affiliation(s)
- Hao Guo
- Department of Cardiology, 1st Affiliated Hospital of Kunming Medical University, Kunming, China
- Department of Cardiology, Yunnan Key Laboratory of Laboratory Medicine, Kunming, Yunnan, China
| | - Li Guo
- Department of Radiology, 2nd Affiliated Hospital of Kunming Medical University, Kunming, Yunnan, China
| | - Yong Yuan
- Department of emergency, 2nd Affiliated Hospital of Kunming Medical University, Kunming, Yunnan, China
| | - Xin-yue Liang
- Department of Cardiology, 1st Affiliated Hospital of Kunming Medical University, Kunming, China
- Department of Cardiology, Graduate School of the Kunming Medical University, Kunming, China
| | - Rui Bi
- Key Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences & Yunnan Province, and KIZ/CUHK Joint Laboratory of Bioresources and Molecular Research in Common Diseases, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan, China
- Kunming College of Life Science, University of Chinese Academy of Sciences, Kunming, Yunnan, China
| |
Collapse
|
6
|
Cytochrome c oxidase deficiency. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2020; 1862:148335. [PMID: 33171185 DOI: 10.1016/j.bbabio.2020.148335] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Revised: 10/31/2020] [Accepted: 11/03/2020] [Indexed: 12/23/2022]
Abstract
Cytochrome c oxidase (COX) deficiency is characterized by a high degree of genetic and phenotypic heterogeneity, partly reflecting the extreme structural complexity, multiple post-translational modification, variable, tissue-specific composition, and the high number of and intricate connections among the assembly factors of this enzyme. In fact, decreased COX specific activity can manifest with different degrees of severity, affect the whole organism or specific tissues, and develop a wide spectrum of disease natural history, including disease onsets ranging from birth to late adulthood. More than 30 genes have been linked to COX deficiency, but the list is still incomplete and in fact constantly updated. We here discuss the current knowledge about COX in health and disease, focusing on genetic aetiology and link to clinical manifestations. In addition, information concerning either fundamental biological features of the enzymes or biochemical signatures of its defects have been provided by experimental in vivo models, including yeast, fly, mouse and fish, which expanded our knowledge on the functional features and the phenotypical consequences of different forms of COX deficiency.
Collapse
|
7
|
Joshi PR, Baty K, Hopton S, Cordts I, Falkous G, Schoser B, Blakely EL, Taylor RW, Deschauer M. Progressive external ophthalmoplegia due to a recurrent de novo m.15990C>T MT-TP (mt-tRNA Pro) gene variant. Neuromuscul Disord 2020; 30:346-350. [PMID: 32305257 DOI: 10.1016/j.nmd.2020.02.020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Revised: 02/11/2020] [Accepted: 02/27/2020] [Indexed: 11/25/2022]
Abstract
Progressive external ophthalmoplegia is typically associated with single or multiple mtDNA deletions but occasionally mtDNA single nucleotide variants within mitochondrial transfer RNAs (mt-tRNAs) are identified. We report a 34-year-old female sporadic patient with progressive external ophthalmoplegia accompanied by exercise intolerance but neither fixed weakness nor multisystemic involvement. Histopathologically, abundant COX-deficient fibres were present in muscle with immunofluorescence analysis confirming the loss of mitochondrial complex I and IV proteins. Molecular genetic analysis identified a rare heteroplasmic m.15990C>T mt-tRNAPro variant reported previously in a single patient with childhood-onset myopathy. The variant in our patient was restricted to muscle. Single muscle fibre analysis identified higher heteroplasmy load in COX-deficient fibres than COX-normal fibres, confirming segregation of high heteroplasmic load with a biochemical defect. Our case highlights the phenotypic variability typically observed with pathogenic mt-tRNA mutations, whilst the identification of a second case with the m.15990C>T mutation not only confirms pathogenicity but shows that de novo mt-tRNA point mutations can arise in multiple, unrelated patients.
Collapse
Affiliation(s)
- Pushpa Raj Joshi
- Department of Neurology, Martin-Luther-University Halle-Wittenberg, Germany.
| | - Karen Baty
- Wellcome Centre for Mitochondrial Research, Newcastle University, Newcastle upon Tyne, United Kingdom; NHS Highly Specialised Mitochondrial Diagnostic Laboratory, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, United Kingdom
| | - Sila Hopton
- Wellcome Centre for Mitochondrial Research, Newcastle University, Newcastle upon Tyne, United Kingdom; NHS Highly Specialised Mitochondrial Diagnostic Laboratory, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, United Kingdom
| | - Isabell Cordts
- Department of Neurology, Technical University Munich, School of Medicine, Munich, Germany
| | - Gavin Falkous
- Wellcome Centre for Mitochondrial Research, Newcastle University, Newcastle upon Tyne, United Kingdom; NHS Highly Specialised Mitochondrial Diagnostic Laboratory, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, United Kingdom
| | - Benedikt Schoser
- Department of Neurology, Friedrich-Baur-Institute, University of Munich, Munich, Germany
| | - Emma L Blakely
- Wellcome Centre for Mitochondrial Research, Newcastle University, Newcastle upon Tyne, United Kingdom; NHS Highly Specialised Mitochondrial Diagnostic Laboratory, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, United Kingdom
| | - Robert W Taylor
- Wellcome Centre for Mitochondrial Research, Newcastle University, Newcastle upon Tyne, United Kingdom; NHS Highly Specialised Mitochondrial Diagnostic Laboratory, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, United Kingdom; Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Marcus Deschauer
- Department of Neurology, Technical University Munich, School of Medicine, Munich, Germany
| |
Collapse
|
8
|
Interpretation of mitochondrial tRNA variants. Genet Med 2020; 22:917-926. [PMID: 31965079 DOI: 10.1038/s41436-019-0746-0] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Accepted: 12/26/2019] [Indexed: 11/08/2022] Open
Abstract
PURPOSE To develop criteria to interpret mitochondrial transfer RNA (mt-tRNA) variants based on unique characteristics of mitochondrial genetics and conserved structural/functional properties of tRNA. METHODS We developed rules on a set of established pathogenic/benign variants by examining heteroplasmy correlations with phenotype, tissue distribution, family members, and among unrelated families from published literature. We validated these deduced rules using our new cases and applied them to classify novel variants. RESULTS Evaluation of previously reported pathogenic variants found that 80.6% had sufficient evidence to support phenotypic correlation with heteroplasmy levels among and within families. The remaining variants were downgraded due to the lack of similar evidence. Application of the verified criteria resulted in rescoring 80.8% of reported variants of uncertain significance (VUS) to benign and likely benign. Among 97 novel variants, none met pathogenic criteria. A large proportion of novel variants (84.5%) remained as VUS, while only 10.3% were likely pathogenic. Detection of these novel variants in additional individuals would facilitate their classification. CONCLUSION Proper interpretation of mt-tRNA variants is crucial for accurate clinical diagnosis and genetic counseling. Correlations with tissue distribution, heteroplasmy levels, predicted perturbations to tRNA structure, and phenotypes provide important evidence for determining the clinical significance of mt-tRNA variants.
Collapse
|
9
|
Ciara E, Rokicki D, Lazniewski M, Mierzewska H, Jurkiewicz E, Bekiesińska-Figatowska M, Piekutowska-Abramczuk D, Iwanicka-Pronicka K, Szymańska E, Stawiński P, Kosińska J, Pollak A, Pronicki M, Plewczyński D, Płoski R, Pronicka E. Clinical and molecular characteristics of newly reported mitochondrial disease entity caused by biallelic PARS2 mutations. J Hum Genet 2018; 63:473-485. [PMID: 29410512 DOI: 10.1038/s10038-017-0401-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Revised: 10/17/2017] [Accepted: 11/29/2017] [Indexed: 01/10/2023]
Abstract
Most of the 19 mitochondrial aminoacyl-tRNA synthetases (mt-aaRSs) involved in mitochondrial protein synthesis are already linked to specific entities, one of the exceptions being PARS2 mutations for which pathogenic significance is not finally validated. The aim of the study was to characterize the PARS2- related phenotype.Three siblings with biallelic PARS2 mutations presented from birth with infantile spasms, secondary microcephaly, and similar facial dysmorphy. Mental development was deeply impaired with speech absence and no eye contact. A dilated cardiomyopathy and multiorgan failure developed in childhood at the terminal stage, together with mitochondrial dysfunction triggered by valproate administration.Brain MRI showed progressive volume loss of the frontal lobes, both cortical and subcortical, with widening of the cortical sulci and frontal horns of the lateral ventricles. Hypoplasia of the corpus callosum and progressive demyelination were additional findings. Similar brain features were seen in three already reported PARS2 patients and seemed specific for this defect when compared with other mt-aaRSs defects (DARS2, EARS2, IARS2, and RARS2).Striking resemblance of the phenotype and Alpers-like brain MRI changes with predominance of frontal cerebral volume loss (FCVL-AS) in six patients from three families of different ethnicity with PARS2 mutations, justifies to distinguish the condition as a new disease entity.
Collapse
Affiliation(s)
- Elżbieta Ciara
- Department of Medical Genetics, The Children's Memorial Health Institute, Warsaw, Poland.
| | - Dariusz Rokicki
- Department of Pediatrics Nutrition and Metabolic Diseases, The Children's Memorial Health Institute, Warsaw, Poland.
| | - Michal Lazniewski
- Centre of New Technologies, University of Warsaw, Banacha 2c Street, 02-071, Warsaw, Poland.,Department of Physical Chemistry, Faculty of Pharmacy, Medical University of Warsaw, Banacha 1, 02-097, Warsaw, Poland
| | - Hanna Mierzewska
- Department of Child Neurology, Institute of Mother and Child, Warsaw, Poland
| | - Elżbieta Jurkiewicz
- Department of Diagnostic Imaging, The Children's Memorial Health Institute, Warsaw, Poland
| | | | | | | | - Edyta Szymańska
- Department of Pediatrics Nutrition and Metabolic Diseases, The Children's Memorial Health Institute, Warsaw, Poland
| | - Piotr Stawiński
- Department of Medical Genetics, Medical University of Warsaw, Warsaw, Poland
| | - Joanna Kosińska
- Department of Medical Genetics, Medical University of Warsaw, Warsaw, Poland
| | - Agnieszka Pollak
- Department of Medical Genetics, Medical University of Warsaw, Warsaw, Poland
| | - Maciej Pronicki
- Department of Pathology, The Children's Memorial Health Institute, Warsaw, Poland
| | - Dariusz Plewczyński
- Centre of New Technologies, University of Warsaw, Banacha 2c Street, 02-071, Warsaw, Poland.,Department of Physical Chemistry, Faculty of Pharmacy, Medical University of Warsaw, Banacha 1, 02-097, Warsaw, Poland.,Faculty of Mathematics and Information Science, Warsaw University of Technology, Warsaw, Poland
| | - Rafał Płoski
- Department of Medical Genetics, Medical University of Warsaw, Warsaw, Poland
| | - Ewa Pronicka
- Department of Medical Genetics, The Children's Memorial Health Institute, Warsaw, Poland.,Department of Pediatrics Nutrition and Metabolic Diseases, The Children's Memorial Health Institute, Warsaw, Poland
| |
Collapse
|
10
|
Frazier AE, Thorburn DR, Compton AG. Mitochondrial energy generation disorders: genes, mechanisms, and clues to pathology. J Biol Chem 2017; 294:5386-5395. [PMID: 29233888 DOI: 10.1074/jbc.r117.809194] [Citation(s) in RCA: 154] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Inherited disorders of oxidative phosphorylation cause the clinically and genetically heterogeneous diseases known as mitochondrial energy generation disorders, or mitochondrial diseases. Over the last three decades, mutations causing these disorders have been identified in almost 290 genes, but many patients still remain without a molecular diagnosis. Moreover, while our knowledge of the genetic causes is continually expanding, our understanding into how these defects lead to cellular dysfunction and organ pathology is still incomplete. Here, we review recent developments in disease gene discovery, functional characterization, and shared pathogenic parameters influencing disease pathology that offer promising avenues toward the development of effective therapies.
Collapse
Affiliation(s)
- Ann E Frazier
- From the Murdoch Children's Research Institute, Royal Children's Hospital and Department of Paediatrics, University of Melbourne, and
| | - David R Thorburn
- From the Murdoch Children's Research Institute, Royal Children's Hospital and Department of Paediatrics, University of Melbourne, and.,Victorian Clinical Genetic Services, Royal Children's Hospital, Melbourne, Victoria 3052, Australia
| | - Alison G Compton
- From the Murdoch Children's Research Institute, Royal Children's Hospital and Department of Paediatrics, University of Melbourne, and
| |
Collapse
|
11
|
Non-coding RNAs and disease: the classical ncRNAs make a comeback. Biochem Soc Trans 2017; 44:1073-8. [PMID: 27528754 DOI: 10.1042/bst20160089] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Indexed: 01/16/2023]
Abstract
Many human diseases have been attributed to mutation in the protein coding regions of the human genome. The protein coding portion of the human genome, however, is very small compared with the non-coding portion of the genome. As such, there are a disproportionate number of diseases attributed to the coding compared with the non-coding portion of the genome. It is now clear that the non-coding portion of the genome produces many functional non-coding RNAs and these RNAs are slowly being linked to human diseases. Here we discuss examples where mutation in classical non-coding RNAs have been attributed to human disease and identify the future potential for the non-coding portion of the genome in disease biology.
Collapse
|
12
|
Morel G, Bannwarth S, Chaussenot A, Cano A, Fragaki K, Ait-El-Mkadem S, Rouzier C, De Paula AM, Chabrol B, Paquis-Flucklinger V. A new mutation in the mitochondrial tRNAPro gene associated with early-onset neuromuscular phenotype and ragged-red fibers. Neuromuscul Disord 2016; 26:885-889. [DOI: 10.1016/j.nmd.2016.09.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Revised: 09/05/2016] [Accepted: 09/12/2016] [Indexed: 10/21/2022]
|
13
|
Duechler M, Leszczyńska G, Sochacka E, Nawrot B. Nucleoside modifications in the regulation of gene expression: focus on tRNA. Cell Mol Life Sci 2016; 73:3075-95. [PMID: 27094388 PMCID: PMC4951516 DOI: 10.1007/s00018-016-2217-y] [Citation(s) in RCA: 89] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Revised: 03/25/2016] [Accepted: 04/04/2016] [Indexed: 01/10/2023]
Abstract
Both, DNA and RNA nucleoside modifications contribute to the complex multi-level regulation of gene expression. Modified bases in tRNAs modulate protein translation rates in a highly dynamic manner. Synonymous codons, which differ by the third nucleoside in the triplet but code for the same amino acid, may be utilized at different rates according to codon-anticodon affinity. Nucleoside modifications in the tRNA anticodon loop can favor the interaction with selected codons by stabilizing specific base pairs. Similarly, weakening of base pairing can discriminate against binding to near-cognate codons. mRNAs enriched in favored codons are translated in higher rates constituting a fine-tuning mechanism for protein synthesis. This so-called codon bias establishes a basic protein level, but sometimes it is necessary to further adjust the production rate of a particular protein to actual requirements, brought by, e.g., stages in circadian rhythms, cell cycle progression or exposure to stress. Such an adjustment is realized by the dynamic change of tRNA modifications resulting in the preferential translation of mRNAs coding for example for stress proteins to facilitate cell survival. Furthermore, tRNAs contribute in an entirely different way to another, less specific stress response consisting in modification-dependent tRNA cleavage that contributes to the general down-regulation of protein synthesis. In this review, we summarize control functions of nucleoside modifications in gene regulation with a focus on recent findings on protein synthesis control by tRNA base modifications.
Collapse
Affiliation(s)
- Markus Duechler
- Centre of Molecular and Macromolecular Studies, Polish Academy of Sciences, Sienkiewicza 112, 90-363, Lodz, Poland.
| | - Grażyna Leszczyńska
- Institute of Organic Chemistry, Lodz University of Technology, Zeromskiego 116, 90-924, Lodz, Poland
| | - Elzbieta Sochacka
- Institute of Organic Chemistry, Lodz University of Technology, Zeromskiego 116, 90-924, Lodz, Poland
| | - Barbara Nawrot
- Centre of Molecular and Macromolecular Studies, Polish Academy of Sciences, Sienkiewicza 112, 90-363, Lodz, Poland
| |
Collapse
|
14
|
Kirchner S, Ignatova Z. Emerging roles of tRNA in adaptive translation, signalling dynamics and disease. Nat Rev Genet 2014; 16:98-112. [DOI: 10.1038/nrg3861] [Citation(s) in RCA: 355] [Impact Index Per Article: 35.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
|
15
|
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] [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).
Collapse
Affiliation(s)
- Sara Roos
- Department of Pathology, Institute of Biomedicine, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden.
| | | | | | | | | | | | | | | |
Collapse
|
16
|
Shanske S, Naini A, Chmait RH, Akman HO, Mansukhani M, Lu J, Hirano M, DiMauro S. Mutation in an mtDNA protein-coding gene: prenatal diagnosis aided by fetal muscle biopsy. J Child Neurol 2013; 28:264-8. [PMID: 22532554 PMCID: PMC3959766 DOI: 10.1177/0883073812441067] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Prenatal diagnosis of disorders due to mitochondrial DNA (mtDNA) tRNA gene mutations is problematic. Experience in families harboring the protein-coding ATPase 6 m.8993T>G mutation suggests that the mutant load is homogeneous in different tissues, thus allowing prenatal diagnosis. We have encountered a novel protein-coding gene mutation, m.10198C>T in MT-ND3. A baby girl homoplasmic for this mutation died at 3 months after severe psychomotor regression and respiratory arrest. The mother had no detectable mutation in accessible tissues. The product of a second pregnancy showed only wild-type mt genomes in amniocytes, chorionic villi, and biopsied fetal muscle. This second girl is now 18 months old and healthy. Our observations support the concept that the pathogenic mutation in this patient appeared de novo and that fetal muscle biopsy is a useful aide in prenatal diagnosis.
Collapse
Affiliation(s)
- Sara Shanske
- Department of Neurology, Columbia University Medical Center, New York, NY, USA
| | - Ali Naini
- Department of Neurology, Columbia University Medical Center, New York, NY, USA,Department of Pathology and Cell Biology, Columbia University Medical Center, New York, NY, USA
| | - Ramen H. Chmait
- Department of Obstetrics, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Hasan O. Akman
- Department of Neurology, Columbia University Medical Center, New York, NY, USA
| | - Mahesh Mansukhani
- Department of Pathology and Cell Biology, Columbia University Medical Center, New York, NY, USA
| | - Jiesheng Lu
- Department of Neurology, Columbia University Medical Center, New York, NY, USA
| | - Michio Hirano
- Department of Neurology, Columbia University Medical Center, New York, NY, USA
| | - Salvatore DiMauro
- Department of Neurology, Columbia University Medical Center, New York, NY, USA
| |
Collapse
|
17
|
Pinós T, Melià MJ, Ortiz N, Martinez-Vea A, Raventós-Estellé A, Gallardo E, Hernández-Losa J, Cámara Y, Andreu AL, García-Arumí E. Identification of the novel mutation m.5658T>C in the mitochondrial tRNA(Asn) gene in a patient with myopathy, bilateral ptosis and ophthalmoparesis. Neuromuscul Disord 2013; 23:330-6. [PMID: 23375258 DOI: 10.1016/j.nmd.2013.01.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2012] [Revised: 09/25/2012] [Accepted: 01/02/2013] [Indexed: 12/13/2022]
Abstract
We report a heteroplasmic novel mutation m.5658T>C in the mt-tRNA(Asn) gene in a patient who initially presented myopathy, bilateral ptosis and ophthalmoparesis and several years later developed a non-nephrotic proteinuria. The muscle biopsy showed cytochrome c oxidase (COX) negative and ragged red fibers and in the kidney biopsy that was taken in order to identify the causes of non-nephrotic proteinuria, a focal segmental glomerulosclerosis was observed. Using laser capture microdissection we isolated COX negative fibers and COX positive fibers from the muscle of the patient and determined that there was a clear increase in the mutation load in the COX negative muscle fibers. However, the low degree of mutation load found in the renal biopsy of the patient does not allow us to conclude that the m.5658T>C mutation is responsible for focal glomerulosclerosis. Additionally, we hypothesize that the mutated m.5658T nucleotide might be structurally relevant, as it is one of the fifteen nucleotides conserved in all the species analyzed and is situated contiguously to the discriminator base in the 3'end of the mt-tRNA, where the tRNase Z cleaves the 3' trailer sequence during mt-tRNA maturation.
Collapse
Affiliation(s)
- Tomàs Pinós
- Departament de Patología Mitocondrial i Neuromuscular, Hospital Universitari Vall d'Hebron Institut de Recerca, Universitat Autònoma de Barcelona, Barcelona, Spain
| | | | | | | | | | | | | | | | | | | |
Collapse
|
18
|
Cardena MMSG, Mansur AJ, Pereira ADC, Fridman C. A new duplication in the mitochondrially encoded tRNA proline gene in a patient with dilated cardiomyopathy. ACTA ACUST UNITED AC 2012; 24:46-9. [PMID: 22954281 DOI: 10.3109/19401736.2012.717933] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Mitochondria provide an environment conducive to mutations in DNA molecules (mtDNA). Analyses of mtDNA have shown mutations potentially leading to many cardiovascular traits. Here, we describe a patient with dilated cardiomyopathy and new mtDNA duplication. The patient presented symptoms of heart failure New York Heart Association functional class III and was diagnosed with non-familial dilated cardiomyopathy with important left ventricular systolic dysfunction. Sequencing of mtDNA control region was done, and a 15 bp duplication was observed between nucleotides 16,018 and 16,032. Part of this duplication is localized within the tRNA proline gene (tRNA(Pro)) that has an important role in cell protection against oxidative stress and is considered an important regulatory factor for cellular reactive oxygen species balance. This duplication could alter the stability or secondary structure of tRNA(Pro), affecting mt-protein synthesis. In turn, the presence of duplication in tRNA(Pro) could cause some oxidative stress imbalance and, so, mitochondrial dysfunction could result in the pathogenicity.
Collapse
Affiliation(s)
- Mari Maki Siria Godoy Cardena
- Department of Legal Medicine, Ethics and Occupational Health, Medical School, University of São Paulo, São Paulo, Brazil
| | | | | | | |
Collapse
|
19
|
Clinical and cellular consequences of the mutation m.12300G>A in the mitochondrial tRNA(Leu(CUN)) gene. Mitochondrion 2011; 12:288-93. [PMID: 22094595 DOI: 10.1016/j.mito.2011.10.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2011] [Revised: 10/27/2011] [Accepted: 10/28/2011] [Indexed: 11/22/2022]
Abstract
We report, for the first time, a patient with an overlap MERRF-NARP syndrome who carries the mutation m.12300G>A in the mitochondrial tRNA(Leu(CUN)) gene. The mutation was heteroplamic and more abundant in her muscle and fibroblast than in blood from her oligosymptomatic mother. Single muscle fiber analysis revealed that the proportion of mutant mtDNA in ragged red fibers was higher than that in normal fibers. Combined defects of mitochondrial respiratory chain complexes were detected in muscle, fibroblasts and transmitochondrial hybrid cells. Significant reduction of total ATP and mitochondrial membrane potential and an increased production of reactive oxygen species were observed.
Collapse
|
20
|
Yarham JW, Elson JL, Blakely EL, McFarland R, Taylor RW. Mitochondrial tRNA mutations and disease. WILEY INTERDISCIPLINARY REVIEWS-RNA 2010; 1:304-24. [DOI: 10.1002/wrna.27] [Citation(s) in RCA: 121] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- John W. Yarham
- Mitochondrial Research Group, Institute for Ageing and Health, The Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Joanna L. Elson
- Mitochondrial Research Group, Institute for Ageing and Health, The Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Emma L. Blakely
- Mitochondrial Research Group, Institute for Ageing and Health, The Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Robert McFarland
- Mitochondrial Research Group, Institute for Ageing and Health, The Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Robert W. Taylor
- Mitochondrial Research Group, Institute for Ageing and Health, The Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| |
Collapse
|
21
|
Scaglia F, Wong LJC. Human mitochondrial transfer RNAs: role of pathogenic mutation in disease. Muscle Nerve 2008; 37:150-71. [PMID: 17999409 DOI: 10.1002/mus.20917] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The human mitochondrial genome encodes 13 proteins. All are subunits of the respiratory chain complexes involved in energy metabolism. These proteins are translated by a set of 22 mitochondrial transfer RNAs (tRNAs) that are required for codon reading. Human mitochondrial tRNA genes are hotspots for pathogenic mutations and have attracted interest over the last two decades with the rapid discovery of point mutations associated with a vast array of neuromuscular disorders and diverse clinical phenotypes. In this review, we use a scoring system to determine the pathogenicity of the mutations and summarize the current knowledge of structure-function relationships of these mutant tRNAs. We also provide readers with an overview of a large variety of mechanisms by which mutations may affect the mitochondrial translation machinery and cause disease.
Collapse
Affiliation(s)
- Fernando Scaglia
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, Texas 77030, USA
| | | |
Collapse
|
22
|
Sacconi S, Salviati L, Nishigaki Y, Walker WF, Hernandez-Rosa E, Trevisson E, Delplace S, Desnuelle C, Shanske S, Hirano M, Schon EA, Bonilla E, De Vivo DC, DiMauro S, Davidson MM. A functionally dominant mitochondrial DNA mutation. Hum Mol Genet 2008; 17:1814-20. [PMID: 18337306 PMCID: PMC2900892 DOI: 10.1093/hmg/ddn073] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Mutations in mitochondrial DNA (mtDNA) tRNA genes can be considered functionally recessive because they result in a clinical or biochemical phenotype only when the percentage of mutant molecules exceeds a critical threshold value, in the range of 70-90%. We report a novel mtDNA mutation that contradicts this rule, since it caused a severe multisystem disorder and respiratory chain (RC) deficiency even at low levels of heteroplasmy. We studied a 13-year-old boy with clinical, radiological and biochemical evidence of a mitochondrial disorder. We detected a novel heteroplasmic C>T mutation at nucleotide 5545 of mtDNA, which was present at unusually low levels (<25%) in affected tissues. The pathogenic threshold for the mutation in cybrids was between 4 and 8%, implying a dominant mechanism of action. The mutation affects the central base of the anticodon triplet of tRNA(Trp) and it may alter the codon specificity of the affected tRNA. These findings introduce the concept of dominance in mitochondrial genetics and pose new diagnostic challenges, because such mutations may easily escape detection. Moreover, similar mutations arising stochastically and accumulating in a minority of mtDNA molecules during the aging process may severely impair RC function in cells.
Collapse
Affiliation(s)
- Sabrina Sacconi
- Féderation des maladies neuromusculaires, CHU de Nice and INSERM U638, Nice, France
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
23
|
Ling J, Roy H, Qin D, Rubio MAT, Alfonzo JD, Fredrick K, Ibba M. Pathogenic mechanism of a human mitochondrial tRNAPhe mutation associated with myoclonic epilepsy with ragged red fibers syndrome. Proc Natl Acad Sci U S A 2007; 104:15299-304. [PMID: 17878308 PMCID: PMC2000536 DOI: 10.1073/pnas.0704441104] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2007] [Indexed: 11/18/2022] Open
Abstract
Human mitochondrial tRNA (hmt-tRNA) mutations are associated with a variety of diseases including mitochondrial myopathies, diabetes, encephalopathies, and deafness. Because the current understanding of the precise molecular mechanisms of these mutations is limited, there is no efficient method to treat their associated mitochondrial diseases. Here, we use a variety of known mutations in hmt-tRNA(Phe) to investigate the mechanisms that lead to malfunctions. We tested the impact of hmt-tRNA(Phe) mutations on aminoacylation, structure, and translation elongation-factor binding. The majority of the mutants were pleiotropic, exhibiting defects in aminoacylation, global structure, and elongation-factor binding. One notable exception was the G34A anticodon mutation of hmt-tRNA(Phe) (mitochondrial DNA mutation G611A), which is associated with MERRF (myoclonic epilepsy with ragged red fibers). In vitro, the G34A mutation decreases aminoacylation activity by 100-fold, but does not affect global folding or recognition by elongation factor. Furthermore, G34A hmt-tRNA(Phe) does not undergo adenosine-to-inosine (A-to-I) editing, ruling out miscoding as a possible mechanism for mitochondrial malfunction. To improve the aminoacylation state of the mutant tRNA, we modified the tRNA binding domain of the nucleus-encoded human mitochondrial phenylalanyl-tRNA synthetase, which aminoacylates hmt-tRNA(Phe) with cognate phenylalanine. This variant enzyme displayed significantly improved aminoacylation efficiency for the G34A mutant, suggesting a general strategy to treat certain classes of mitochondrial diseases by modification of the corresponding nuclear gene.
Collapse
Affiliation(s)
| | - Hervé Roy
- Department of Microbiology, and
- Ohio State RNA Group, Ohio State University, Columbus, OH 43210
| | | | - Mary Anne T. Rubio
- Department of Microbiology, and
- Ohio State RNA Group, Ohio State University, Columbus, OH 43210
| | - Juan D. Alfonzo
- *Ohio State Biochemistry Program
- Department of Microbiology, and
- Ohio State RNA Group, Ohio State University, Columbus, OH 43210
| | - Kurt Fredrick
- *Ohio State Biochemistry Program
- Department of Microbiology, and
- Ohio State RNA Group, Ohio State University, Columbus, OH 43210
| | - Michael Ibba
- *Ohio State Biochemistry Program
- Department of Microbiology, and
- Ohio State RNA Group, Ohio State University, Columbus, OH 43210
| |
Collapse
|
24
|
Abstract
The small, maternally inherited mtDNA has turned out to be a Pandora's box of pathogenic mutations: 12 years into the era of "mitochondrial medicine," about 100 pathogenic point mutations and innumerable rearrangements have been associated with a bewildering variety of multisystemic as well as tissue-specific human diseases. After reviewing the principles of mitochondrial genetics, we compare and contrast the clinical and pathological features of disorders due to mutations in genes affecting mitochondrial protein synthesis with those of mutations in protein-coding genes. In contrast to the striking progress in our understanding of etiology, pathogenesis is only partially explained by the rules of mitochondrial genetics and remains largely terra incognita. We review recent progress in prenatal diagnosis and epidemiology. Therapy is still woefully inadequate, but a number of promising approaches are being developed.
Collapse
Affiliation(s)
- S DiMauro
- Department of Neurology, Columbia University College of Physicians & Surgeons, New York, NY 10032, USA.
| | | |
Collapse
|
25
|
Müller T, Deschauer M, Neudecker S, Zierz S. Late-onset mitochondrial myopathy with dystrophic changes due to a G7497A mutation in the mitochondrial tRNA(Ser(UCN)) gene. Acta Neuropathol 2005; 110:426-30. [PMID: 16133542 DOI: 10.1007/s00401-005-1063-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2005] [Revised: 06/30/2005] [Accepted: 06/30/2005] [Indexed: 11/28/2022]
Abstract
Mutations of mitochondrial tRNA genes are usually associated with multi-systemic disorders with onset of symptoms in childhood or early adulthood. Dystrophic myopathic changes are not typical features of these disorders. We report two siblings with a severe progressive myopathy of late onset without external ophthalmoplegia and without involvement of the central and peripheral nervous system. Muscle biopsy specimens showed severe myopathic changes similar to those found in muscular dystrophies. Molecular analysis revealed a G7497A mutation in the mitochondrial tRNA(Ser(UCN)) gene. In both patients, the proportion of mutated mitochondrial DNA in muscle was more than 97%. Mitochondrial disorder associated with the G7497A mutation has to be included into the differential diagnosis of severe progressive late-onset myopathy with histopathological dystrophic myopathic changes. Mitochondrial myopathy and high level of mutated mtDNA might be a characteristic of the G7497A tRNA(Ser(UCN)) mutation.
Collapse
Affiliation(s)
- Tobias Müller
- Universitätsklinik und Poliklinik für Neurologie, Martin-Luther-Universität Halle-Wittenberg, Ernst-Grube-Str. 40, 06097, Halle (Saale), Germany.
| | | | | | | |
Collapse
|
26
|
Anitori R, Manning K, Quan F, Weleber RG, Buist NRM, Shoubridge EA, Kennaway NG. Contrasting phenotypes in three patients with novel mutations in mitochondrial tRNA genes. Mol Genet Metab 2005; 84:176-88. [PMID: 15670724 DOI: 10.1016/j.ymgme.2004.10.003] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/29/2004] [Revised: 10/01/2004] [Accepted: 10/02/2004] [Indexed: 11/22/2022]
Abstract
We studied three patients, each harboring a novel mutation at a highly conserved position in a different mitochondrial tRNA gene. The mutation in patient 1 (T5543C) was associated with isolated mitochondrial myopathy, and occurred in the anticodon loop of tRNA(Trp). In patient 2, with mitochondrial myopathy and marked retinopathy, the mutation (G14710A) resulted in an anticodon swap (Glu to Lys) in tRNA(Glu). Patient 3, who manifested mitochondrial encephalomyopathy and moderate retinal dysfunction, harbored a mutation (C3287A) in the TpsiC loop of tRNA(Leu(UUR)). The mutations were heteroplasmic in muscle in all cases, and sporadic in two cases. PCR-RFLP analysis in all patients showed much higher amounts of mutated mtDNA in affected tissue (muscle) than unaffected tissue (blood), and significantly higher levels of mutated mtDNA in cytochrome c oxidase (COX)-negative muscle fibers than in COX-positive fibers, confirming the pathogenicity of these mutations. The mutation was also detected in single hair roots from all three patients, indicating that each mutation must have arisen early in embryonic development or in maternal germ cells. This suggests that individual hair root analyses may reflect a wider tissue distribution of mutated mtDNA than is clinically apparent, and might be useful in predicting prognosis and, perhaps, the risk of transmitting the mutation to offspring. Our data suggest a correlation between clinical phenotype and distribution of mutated mtDNA in muscle versus hair roots. Furthermore, the high threshold for phenotypic expression in single muscle fibers (92-96%) suggests that therapies may only need to increase the percentage of wild-type mtDNA by a small amount to be beneficial.
Collapse
Affiliation(s)
- Roberto Anitori
- Department of Molecular and Medical Genetics, Oregon Health & Science University, Portland, OR 97239, USA
| | | | | | | | | | | | | |
Collapse
|
27
|
Moraes CT, Atencio DP, Oca-Cossio J, Diaz F. Techniques and pitfalls in the detection of pathogenic mitochondrial DNA mutations. J Mol Diagn 2004; 5:197-208. [PMID: 14573777 PMCID: PMC1907336 DOI: 10.1016/s1525-1578(10)60474-6] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Mutations in the mitochondrial DNA (mtDNA) are now recognized as major contributors to human pathologies and possibly to normal aging. A large number of rearrangements and point mutations in protein coding and tRNA genes have been identified in patients with mitochondrial disorders. In this review, we discuss genotype-phenotype correlations in mitochondrial diseases and common techniques used to identify pathogenic mtDNA mutations in human tissues. Although most of these approaches employ standard molecular biology tools, the co-existence of wild-type and mutated mtDNA (mtDNA heteroplasmy) in diseased tissues complicates both the detection and accurate determination of the size of the mutated fractions. To address these problems, novel approaches were developed and are discussed in this review.
Collapse
Affiliation(s)
- Carlos T Moraes
- Department of Neurology, University of Miami School of Medicine, Miami, Florida 33136, USA.
| | | | | | | |
Collapse
|
28
|
Moslemi AR, Lindberg C, Toft J, Holme E, Kollberg G, Oldfors A. A novel mutation in the mitochondrial tRNAPhe gene associated with mitochondrial myopathy. Neuromuscul Disord 2004; 14:46-50. [PMID: 14659412 DOI: 10.1016/s0960-8966(03)00168-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
We report a novel heteroplasmic T-->C mutation at nt position 582 within the mitochondrial tRNA(Phe) gene of a 70-year-old woman with mitochondrial myopathy. No other family members were affected, suggesting that our patient was a sporadic case. The muscle showed frequent ragged red fibers and 43% cytochrome c oxidase deficient fibers. The mutation alters a conserved base pairing in the aminoacyl acceptor stem. The mutation load was 70% in muscle homogenate and varied from 0 to 95% in individual muscle fiber segments. Cytochrome c oxidase-negative fibers showed significantly higher levels of mutated mtDNA (>75%) than Cytochrome c oxidase-positive fibers (<55%). This mutation adds to the previously described four pathogenic mutations in the tRNA(Phe) gene.
Collapse
Affiliation(s)
- A-R Moslemi
- Department of Pathology, Sahlgrenska University Hospital, 41345 Göteborg, Sweden.
| | | | | | | | | | | |
Collapse
|
29
|
Rahim F, Gupta D, Bertorini TE, Ledoux MS. Dropped head presentation of mitochondrial myopathy. J Clin Neuromuscul Dis 2003; 5:108-114. [PMID: 19078729 DOI: 10.1097/00131402-200312000-00007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Dropped head secondary to weakness of the neck extensors has been reported in a wide assortment of neuromuscular disorders. Infrequently, dropped head can be the first sign of disease. We describe two patients with dropped head as the presenting manifestation of mitochondrial myopathy. In both patients, serum lactate was elevated and muscle biopsy showed mitochondrial proliferation. Mitochondrial myopathy should be considered in the differential diagnosis of dropped head syndrome, particularly when other, more common causes such as myasthenia gravis, polymyositis, and amyotrophic lateral sclerosis have been excluded by appropriate laboratory and electrophysiological studies.
Collapse
Affiliation(s)
- Fazal Rahim
- From the Department of Neurology, University of Tennessee Health Science Center Memphis
| | | | | | | |
Collapse
|
30
|
Kraytsberg Y, Nekhaeva E, Bodyak NB, Khrapko K. Mutation and intracellular clonal expansion of mitochondrial genomes: two synergistic components of the aging process? Mech Ageing Dev 2003; 124:49-53. [PMID: 12618006 DOI: 10.1016/s0047-6374(02)00169-0] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The foundations of the Mitochondrial mutational theory of aging include two assumptions: the high abundance of mitochondrial mutations and their ability to clonally expand within individual cells. The up-to-date data pertinent to these assumptions is reviewed and semi-quantitative estimates of the frequencies of mutants and intracellular expansions are offered. The incidence of mutations in various aged tissues may be on the order of one mutant per mitochondrial genome copy, and most of the cells are likely to be affected by intracellular clonal expansions of mitochondrial genomes. Thus aged tissue may be considered a mosaic of cells with different mutant mitochondrial genotypes. Interestingly, independent studies show that a wide range of aged tissues presents with a mosaic of cells with different mitochondrial phenotypes. The necessary methodologies are available to explore whether the two mosaics are causally related. The answer apparently is positive in muscle; other tissues, brain in particular, await exploration.
Collapse
Affiliation(s)
- Yevgenya Kraytsberg
- Beth Israel Deaconess Medical Center and Harvard Medical School, Rm. 921, 77 Ave. L. Pasteur, Boston, MA 02215, USA
| | | | | | | |
Collapse
|
31
|
Hancock DK, Schwarz FP, Song F, Wong LJC, Levin BC. Design and Use of a Peptide Nucleic Acid for Detection of the Heteroplasmic Low-Frequency Mitochondrial Encephalomyopathy, Lactic Acidosis, and Stroke-like Episodes (MELAS) Mutation in Human Mitochondrial DNA. Clin Chem 2002. [DOI: 10.1093/clinchem/48.12.2155] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Abstract
Background: Most pathogenic human mitochondrial DNA (mtDNA) mutations are heteroplasmic (i.e., mutant and wild-type mtDNA coexist in the same individual) and are difficult to detect when their concentration is a small proportion of that of wild-type mtDNA molecules. We describe a simple methodology to detect low proportions of the single base pair heteroplasmic mutation, A3243G, that has been associated with the disease mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) in total DNA extracted from blood.
Methods: Three peptide nucleic acids (PNAs) were designed to bind to the wild-type mtDNA in the region of nucleotide position 3243, thus blocking PCR amplification of the wild-type mtDNA while permitting the mutant DNA to become the dominant product and readily discernable. DNA was obtained from both apparently healthy and MELAS individuals. Optimum PCR temperatures were based on the measured ultraviolet thermal stability of the DNA/PNA duplexes. The presence or absence of the mutation was determined by sequencing.
Results: In the absence of PNAs, the heteroplasmic mutation was either difficult to detect or undetectable by PCR and sequencing. Only PNA 3 successfully inhibited amplification of the wild-type mtDNA while allowing the mutant mtDNA to amplify. In the presence of PNA 3, we were able to detect the heteroplasmic mutation when its concentration was as low as 0.1% of the concentration of the wild-type sequence.
Conclusion: This methodology permits easy detection of low concentrations of the MELAS A3243G mutation in blood by standard PCR and sequencing methods.
Collapse
Affiliation(s)
- Diane K Hancock
- Biotechnology Division, National Institute of Standards and Technology, Gaithersburg, MD 20899
| | - Frederick P Schwarz
- Biotechnology Division, National Institute of Standards and Technology, Gaithersburg, MD 20899
| | - Fenhong Song
- University of Maryland Biotechnology Institute, Center for Advanced Research in Biotechnology, Rockville, MD 20850
| | - Lee-Jun C Wong
- Institute for Molecular and Human Genetics, Georgetown University Medical Center, Washington, DC 20007
| | - Barbara C Levin
- Biotechnology Division, National Institute of Standards and Technology, Gaithersburg, MD 20899
| |
Collapse
|
32
|
Taylor RW, Schaefer AM, McFarland R, Maddison P, Turnbull DM. A novel mitochondrial DNA tRNA(Ile) (A4267G) mutation in a sporadic patient with mitochondrial myopathy. Neuromuscul Disord 2002; 12:659-664. [PMID: 12207935 DOI: 10.1016/s0960-8966(02)00026-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We describe a novel mutation in the mitochondrial tRNA(Ile) gene, an A to G transition at nucleotide position 4267, in a 37-year-old woman with myopathy, ataxia and sensorineural hearing loss. The A4267G mutation was heteroplasmic in several of the proband's tissues and single fibre analysis revealed significantly higher levels of mutated mitochondrial DNA in cytochrome c oxidase-deficient fibres than cytochrome c oxidase-positive fibres. It is predicted to disrupt a highly conserved base pair within the aminoacyl acceptor stem of the tRNA causing functional impairment, and as such fulfils all the accepted criteria for pathogenicity. Moreover, we were unable to detect the A4267G mutation in lymphocytes, buccal epithelia and hair of the patient's mother and two siblings, implying that the A4267G transition represents a sporadic, germline mutation.
Collapse
Affiliation(s)
- Robert W Taylor
- Department of Neurology, The Medical School, University of Newcastle upon Tyne, Framlington Place, NE2 4HH, Newcastle upon Tyne, UK.
| | | | | | | | | |
Collapse
|
33
|
Abstract
Since the first reports of disorders associated with mitochondrial DNA (mtDNA) defects more than a decade ago, the small mtDNA circle has been a Pandora's box of pathogenic mutations associated with human diseases. The "morbidity map" of mtDNA has gone from one point mutation and a few deletions in 1988 to more than 110 point mutations as of September, 2001. Nuclear DNA defects affecting mitochondrial function and mtDNA replication and integrity have also been identified in the past few years and more are expected. As a result, human "mitochondrial" diseases have evolved beyond the novelty diagnoses of a decade ago into an important area of medicine, and thus, the diagnostic principles of these disorders ought to be familiar to the clinician. In this article, the authors, we summarize the principles of mitochondrial genetics and discuss the common phenotypes, general diagnostic approach, and possible therapeutic venues for these fascinating disorders.
Collapse
Affiliation(s)
- Tuan H Vu
- Department of Neurology, Columbia University College of Physicians & Surgeons, New York, NY, USA
| | | | | |
Collapse
|
34
|
Nekhaeva E, Kraytsberg Y, Khrapko K. mtLOH (mitochondrial loss of heteroplasmy), aging, and 'surrogate self'. Mech Ageing Dev 2002; 123:891-8. [PMID: 12044937 DOI: 10.1016/s0047-6374(02)00026-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
In tribute to Dr Strehler, an attempt is made to use a style of reasoning found in some of his later papers as an outline of this article. First, general arguments in favor of the involvement of somatic mutations in mtDNA in the aging process are presented. Second, evidence is provided in support of a general tendency of mitochondrial genomes to reach homoplasmic state at the cellular level, for which we propose the term mitochondrial loss of heteroplasmy (mtLOH). This process is likely to facilitate the involvement of mtDNA mutations in the aging process by streamlining the phenotypic expression of the mutant genotype. Third, preliminary evidence of the very high incidence of clonal deletions in pigmented neurons of substantia nigra is reported. This observation highlights the possibility that accumulation of mtDNA mutations specific in certain cell types of a complex tissue may account for the involvement of mtDNA mutations in the aging process despite the relatively low average incidence of these mutations in the tissue as a whole. High incidence of mtDNA deletions in pigmented neurons evokes Strehler's idea that efforts to delay aging may not be the most cost-efficient way of preserving 'self awareness and a joyful sense of life', as he put it. A potential alternative suggested by Strehler, i.e. creation of a 'surrogate self' by computer simulation may deserve more attention than it currently enjoys.
Collapse
Affiliation(s)
- Ekaterina Nekhaeva
- Beth Israel Deaconess Medical Center and Harvard Medical School, Rm. 921, 77 Ave. L. Pasteur, Boston, MA 02115, USA
| | | | | |
Collapse
|
35
|
Coller HA, Bodyak ND, Khrapko K. Frequent intracellular clonal expansions of somatic mtDNA mutations: significance and mechanisms. Ann N Y Acad Sci 2002; 959:434-47. [PMID: 11976216 DOI: 10.1111/j.1749-6632.2002.tb02113.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
It has been proposed that age-dependent accumulation of somatic mutations in mtDNA is responsible for some aspects of the aging process. However, most cells contain hundreds to thousands of mtDNA molecules. Any nascent somatic mutant therefore appears as a single copy among a majority of wild-type species. A single mutant molecule is unlikely to influence the physiology of the cell and thus cannot play a role in the aging process. To affect cellular physiology, the nascent somatic mutants must somehow accumulate clonally in the cell to significant levels. The evidence supporting the view that, indeed, clonal expansion of mtDNA mutations is a widespread process in various human tissues, and the mechanisms by which clonal expansions may affect the aging process, are reviewed. Originally, clonal expansion was demonstrated for mtDNA with large deletions in muscle. Cell-by-cell analysis of human cardiomyocytes and buccal epithelial cells revealed that clonal expansion affects point mtDNA mutations as well as deletions. Expansions are not limited to muscle, but likely are present in most tissues, and almost every cell of an aged tissue is likely to be affected by an expansion. While the very existence of clonal expansion is beyond doubt, the mechanisms driving this process are largely controversial. The hypotheses explaining expansion includes random or various selective mechanisms, or both. We show that the spectra of expanded point mutations are drastically different in cardiomyocytes and epithelial cells. This suggests that the mechanisms of expansion in these tissues are different. In particular, we propose random segregation and positive selection models for epithelial and muscle cells, respectively.
Collapse
Affiliation(s)
- Hilary A Coller
- Fred Hutchinson Cancer Research Center, Seattle, Washington 98119, USA
| | | | | |
Collapse
|
36
|
DiMauro S, Schon EA. Mitochondrial DNA mutations in human disease. AMERICAN JOURNAL OF MEDICAL GENETICS 2002; 106:18-26. [PMID: 11579421 DOI: 10.1002/ajmg.1392] [Citation(s) in RCA: 308] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The small, maternally inherited mitochondrial DNA (mtDNA) has turned out to be a Pandora's box of pathogenic mutations: 13 years into the era of "molecular mitochondrial medicine," more than 100 pathogenic point mutations and innumerable rearrangements have been associated with a striking variety of multisystemic as well as tissue-specific human diseases. After reviewing the principles of mitochondrial genetics, we consider disorders due to mutations in genes affecting mitochondrial protein synthesis and disorders due to mutations in protein-coding genes. In contrast to the remarkable progress in our understanding of etiology, pathogenesis is only partially explained by the rules of mitochondrial genetics and remains largely unclear. We review recent progress in prenatal diagnosis, epidemiology, and in the development of animal models harboring mtDNA mutations.
Collapse
Affiliation(s)
- S DiMauro
- College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA.
| | | |
Collapse
|
37
|
Chapter 3 Molecular Genetic Basis of the Mitochondrial Encephalomyopathies. ACTA ACUST UNITED AC 2002. [DOI: 10.1016/s1877-3419(09)70062-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
|
38
|
Wong LJ. Recognition of mitochondrial DNA deletion syndrome with non-neuromuscular multisystemic manifestation. Genet Med 2001; 3:399-404. [PMID: 11715003 DOI: 10.1097/00125817-200111000-00004] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
PURPOSE To correlate the molecular characteristics of the mtDNA deletions with clinical phenotypes. METHODS Southern analysis and polymerase chain reaction (PCR)/DNA sequencing were used to determine the size and location of deletions in 16 patients with mtDNA deletion syndrome. An additional 48 reported cases from the literature were also included in the statistical analysis. RESULTS The common 5-kb deletion is found in eight of nine patients with Kearns-Sayre syndrome (KSS), mitochondrial myopathies (MM), or progressive external ophthalmoplegia (PEO). The rare/novel deletions were found in six of seven patients with extra-neuromuscular multisystemic manifestations and infantile/early childhood onset. CONCLUSIONS Patients with mtDNA deletion syndrome who manifest non-neuromuscular multisystemic disorders at a very young age usually harbor mutant mtDNA with novel or rare deletions in every tissue analyzed. For this group of patients, it is possible to use the less invasive blood specimens instead of muscle biopsies for molecular diagnosis. Overwhelmingly, the common 5-kb deletion is mostly seen in the muscle specimens of patients with KSS and age of onset after the second decade of life.
Collapse
Affiliation(s)
- L J Wong
- Institute for Molecular and Human Genetics, Georgetown University Medical Center, Washington, DC 20007, USA
| |
Collapse
|
39
|
Rose G, Passarino G, Carrieri G, Altomare K, Greco V, Bertolini S, Bonafè M, Franceschi C, De Benedictis G. Paradoxes in longevity: sequence analysis of mtDNA haplogroup J in centenarians. Eur J Hum Genet 2001; 9:701-7. [PMID: 11571560 DOI: 10.1038/sj.ejhg.5200703] [Citation(s) in RCA: 102] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2001] [Revised: 06/06/2001] [Accepted: 06/28/2001] [Indexed: 11/09/2022] Open
Abstract
Previous studies have shown that mitochondrial DNA (mtDNA) haplogroup J is significantly over-represented in healthy centenarians with respect to younger controls, thus suggesting that this haplogroup predisposes to successful aging and longevity. On the other hand, the same haplogroup is reported to have elevated frequency in some complex diseases. To verify if centenarians clustered in a particular lineage within J we have sequenced the D-loop region from 18 centenarians and 18 younger controls, previously characterized to be J. Then the entire mtDNA molecule was sequenced in a sub-sample of nine centenarians to find possible functional mutations associated with haplogroup J in successful aging. No clustering of the J haplogroup mtDNA from centenarians was observed. In addition, most of the mutations found are known as disease-associated mutations. The general picture that emerges from the study is that the J haplogroup of centenarians is surprisingly similar to that found in complex diseases, as well as in Leber Hereditary Optic Neuropathy. This finding implies that the same mutations could predispose to disease or longevity, probably according to individual-specific genetic backgrounds and stochastic events. This data reveals another paradox of centenarians and confirms the complexity of the longevity trait.
Collapse
Affiliation(s)
- G Rose
- Department of Cell Biology, University of Calabria, Rende, Italy
| | | | | | | | | | | | | | | | | |
Collapse
|
40
|
Abstract
The mitochondrial encephalomyopathies are a genetically heterogeneous group of disorders associated with impaired oxidative phosphorylation. Patients may exhibit a wide range of clinical symptoms and experience significant morbidity and mortality. There is currently no curative treatment. At present the majority of genetically defined mitochondrial encephalomyopathies are caused by mutations in mitochondrial DNA. The underlying molecular mechanisms and the complex relationship between genotype and phenotype in these mitochondrial DNA diseases remain only partially understood. We describe the key features of mitochondrial DNA genetics and outline some of the common disease phenotypes associated with mtDNA defects. A classification of pathogenic mitochondrial DNA point mutations which may have therapeutic implications is outlined.
Collapse
Affiliation(s)
- T Pulkes
- Muscle and Neurogenetics Sections, University Department of Clinical Neurology, Institute of Neurology, University College London, Queen Square, WC1N 3BG, London, UK
| | | |
Collapse
|
41
|
Abstract
Mitochondrial diseases are a heterogeneous group of disorders with widely varying clinical features, due to defects in mitochondrial function. Involvement of both muscle and nerve is common in mitochondrial disease. In some cases, this involvement is subclinical or a minor part of a multisystem disorder, but myopathy and neuropathy are a major, often presenting, feature of a number of mitochondrial syndromes. In addition, mitochondrial dysfunction may play a role in a number of classic neuromuscular diseases. This article reviews the role of mitochondrial dysfunction in neuromuscular disease and discusses a rational approach to diagnosis and treatment of patients presenting with a neuromuscular syndrome due to mitochondrial disease.
Collapse
Affiliation(s)
- R A Nardin
- Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Harvard Institute of Medicine, Rm 858, 77 Avenue Louis Pasteur, Boston, Massachusetts 02115, USA
| | | |
Collapse
|
42
|
Seneca S, Ceuterik-De Groote C, Van Coster R, De Meirleir L. A novel mitochondrial transfer RNA proline mutation. J Inherit Metab Dis 2000; 23:853-4. [PMID: 11196116 DOI: 10.1023/a:1026729223050] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- S Seneca
- Department of Medical Genetics, Dutch-speaking Free University of Brussels, Belgium.
| | | | | | | |
Collapse
|
43
|
Dey R, Tengan CH, Morita MP, Kiyomoto BH, Moraes CT. A novel myopathy-associated mitochondrial DNA mutation altering the conserved size of the tRNA(Gln) anticodon loop. Neuromuscul Disord 2000; 10:488-92. [PMID: 10996779 DOI: 10.1016/s0960-8966(00)00125-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
We report a novel mitochondrial DNA alteration in a 12-year-old boy with myopathy. We identified a single nucleotide insertion (an adenine) in the mitochondrial tRNA-glutamine gene. This addition of an additional adenine in a polyadenine stretch (at mitochondrial DNA positions 4366-4369), alters the length of the evolutionary conserved anticodon loop from seven to eight bases. The nt-4370 addition was heteroplasmic and was abundant in the patient's muscle. Lower proportions of mutated mitochondrial DNA were observed in skin fibroblasts, but were below detectable levels in white blood cells. A muscle biopsy of the patient showed ragged red fibers and an unusually high percentage of cytochrome c oxidase-deficient fibers (89%). The pathogenicity of the mutation was also evident by the fact that fibers harboring lower levels of the mutation showed normal cytochrome c oxidase activity. The insertion in the anticodon loop of tRNA(Gln) gene identified in our patient may provide a unique tool to study protein synthesis in human mitochondria.
Collapse
Affiliation(s)
- R Dey
- Department of Neurology, University of Miami, School of Medicine, Miami, FL 33136, USA
| | | | | | | | | |
Collapse
|
44
|
Houshmand M, Lindberg C, Moslemi AR, Oldfors A, Holme E. A novel heteroplasmic point mutation in the mitochondrial tRNA(Lys) gene in a sporadic case of mitochondrial encephalomyopathy: de novo mutation and no transmission to the offspring. Hum Mutat 2000; 13:203-9. [PMID: 10090475 DOI: 10.1002/(sici)1098-1004(1999)13:3<203::aid-humu4>3.0.co;2-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
We have identified a new mutation in the tRNA(Lys) gene of mtDNA, in a 49-year-old patient with mitochondrial encephalomyopathy. The mutation is a heteroplasmic G-->A transition at position 8328, which affects the anticodon stem loop at a conserved site. The mutation was neither found in 100 controls nor in the maternal relatives of the patient. The level of mutated mtDNA was 57% in muscle, 13% in fibroblasts, and 10% in lymphocytes. Histochemistry of muscle tissue revealed cytochrome c oxidase-deficient fibers with abnormal accumulation of mitochondria. Biochemistry of muscle mitochondria showed slight cytochrome c oxidase deficiency. The mean ratio of mutant mtDNA to normal mtDNA in cytochrome c oxidase-positive muscle fibers was 59%, whereas a mean ratio of 95% was found in cytochrome c oxidase-negative fibers. The difference between cytochrome c oxidase-positive and cytochrome c oxidase-negative fibers was highly significant (P < 0.001). The mutation was not found in muscle or lymphocytes of the mother and daughter of the proband. This is the first report of a de novo point mutation in the tRNA(Lys) gene in an individual expressing disease and the first report of lack of transmission of the mutation to the offspring of a patient expressing a mitochondrial encephalomyopathy caused by a point mutation in mtDNA.
Collapse
Affiliation(s)
- M Houshmand
- Department of Clinical Chemistry, Göteborg University, Sahlgrenska University Hospital, Gothenburg, Sweden
| | | | | | | | | |
Collapse
|
45
|
Andreu AL, Hanna MG, Reichmann H, Bruno C, Penn AS, Tanji K, Pallotti F, Iwata S, Bonilla E, Lach B, Morgan-Hughes J, DiMauro S. Exercise intolerance due to mutations in the cytochrome b gene of mitochondrial DNA. N Engl J Med 1999; 341:1037-44. [PMID: 10502593 DOI: 10.1056/nejm199909303411404] [Citation(s) in RCA: 336] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
BACKGROUND The mitochondrial myopathies typically affect many organ systems and are associated with mutations in mitochondrial DNA (mtDNA) that are maternally inherited. However, there is also a sporadic form of mitochondrial myopathy in which exercise intolerance is the predominant symptom. We studied the biochemical and molecular characteristics of this sporadic myopathy. METHODS We sequenced the mtDNA cytochrome b gene in blood and muscle specimens from five patients with severe exercise intolerance, lactic acidosis in the resting state (in four patients), and biochemical evidence of complex III deficiency. We compared the clinical and molecular features of these patients with those previously described in four other patients with mutations in the cytochrome b gene. RESULTS We found a total of three different nonsense mutations (G15084A, G15168A, and G15723A), one missense mutation (G14846A), and a 24-bp deletion (from nucleotide 15498 to 15521) in the cytochrome b gene in the five patients. Each of these mutations impairs the enzymatic function of the cytochrome b protein. In these patients and those previously described, the clinical manifestations included progressive exercise intolerance, proximal limb weakness, and in some cases, attacks of myoglobinuria. There was no maternal inheritance and there were no mutations in tissues other than muscle. The absence of these findings suggests that the disorder is due to somatic mutations in myogenic stem cells after germ-layer differentiation. All the point mutations involved the substitution of adenine for guanine, but all were in different locations. CONCLUSIONS The sporadic form of mitochondrial myopathy is associated with somatic mutations in the cytochrome b gene of mtDNA. This myopathy is one cause of the common and often elusive syndrome of exercise intolerance.
Collapse
Affiliation(s)
- A L Andreu
- H. Houston Merritt Clinical Research Center for Muscular Dystrophy and Related Diseases, Department of Neurology, Columbia College of Physicians and Surgeons, New York, NY 10032, USA
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
46
|
Marin-Garcia J, Ananthakrishnan R, Goldenthal MJ, Filiano JJ, Sarnat HB. Skeletal muscle mitochondrial defects in nonspecific neurologic disorders. Pediatr Neurol 1999; 21:538-42. [PMID: 10465139 DOI: 10.1016/s0887-8994(99)00038-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A group of 25 children (5 months to 20 years of age) presenting with intractable seizures, developmental delay, and severe hypotonia, who did not fall into the known categories of mitochondrial encephalomyopathies, underwent muscle biopsy for evaluation of mitochondrial function and were compared with age-matched control subjects. Biopsied skeletal muscle was analyzed for six mitochondrial enzyme-specific activities, mitochondrial DNA point mutations and deletions, and mitochondrial DNA levels. The data reveal a high incidence of specific mitochondrial enzyme activity defects. Reduced activity levels were evident in complex I (11 patients), III (24 patients), IV (nine patients), and V (10 patients). Two patients also exhibited pronounced reduction in mitochondrial DNA levels (80% reduction compared with control subjects). Two patients manifested increased levels of 5-kb and 7.4-kb mitochondrial DNA deletions. Pathogenic mutations previously described in association with mitochondrial encephalomyopathies were not evident. The data suggest that mitochondrial dysfunction, including extensive defects in specific enzyme activities, may be frequently present in children with seizures, developmental delay, and hypotonia that do not fall within the known mitochondrial encephalomyopathies. These mitochondrial deficiencies can be primarily ascertained by biochemical analysis and are rarely accompanied by mitochondrial ultrastructural changes. The molecular basis of these defects, their role in these disorders, and potential treatment warrant further study.
Collapse
Affiliation(s)
- J Marin-Garcia
- Molecular Cardiology Institute, Highland Park, New Jersey 08904, USA
| | | | | | | | | |
Collapse
|
47
|
Andreu AL, Tanji K, Bruno C, Hadjigeorgiou GM, Sue CM, Jay C, Ohnishi T, Shanske S, Bonilla E, DiMauro S. Exercise intolerance due to a nonsense mutation in the mtDNA ND4 gene. Ann Neurol 1999; 45:820-3. [PMID: 10360780 DOI: 10.1002/1531-8249(199906)45:6<820::aid-ana22>3.0.co;2-w] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
We report the first molecular defect in an NADH-dehydrogenase gene presenting as isolated myopathy. The proband had lifelong exercise intolerance but no weakness. A muscle biopsy showed cytochrome c oxidase (COX)-positive ragged-red fibers (RRFs), and analysis of the mitochondrial enzymes revealed complex I deficiency. Sequence analysis of the mitochondrial genes encoding the seven NADH-dehydrogenase subunits showed a G-to-A transition at nucleotide 11832 in the subunit 4 (ND4) gene, which changed an encoded tryptophan to a stop codon. The mutation was heteroplasmic (54%) in muscle DNA. Defects in mitochondrially encoded complex I subunits should be added to the differential diagnosis of mitochondrial myopathies.
Collapse
Affiliation(s)
- A L Andreu
- H. Houston Merritt Center for Muscular Dystrophy and Related Diseases, Department of Neurology, Columbia College of Physicians and Surgeons, New York, NY 10032, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
48
|
Hadjigeorgiou GM, Kim SH, Fischbeck KH, Andreu AL, Berry GT, Bingham P, Shanske S, Bonilla E, DiMauro S. A new mitochondrial DNA mutation (A3288G) in the tRNA(Leu(UUR)) gene associated with familial myopathy. J Neurol Sci 1999; 164:153-7. [PMID: 10402027 DOI: 10.1016/s0022-510x(99)00062-3] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
We describe a family with a maternally inherited mitochondrial myopathy and an A3288G mutation in the tRNA(Leu(UUR)) gene. The proband had muscle cramping and mild weakness while her brother had long-standing limb and respiratory muscle weakness and her daughter had elevated serum CK. The mutation, which was nearly homoplasmic in muscle and heteroplasmic in blood, affects the TpsiC loop at a conserved site and was not found in 107 controls. This report confirms the frequent association of tRNA(Leu(UUR)) mutations with respiratory muscle involvement and bolsters the concept that tRNA(Leu(UUR)) is a hotspot for mtDNA mutations.
Collapse
Affiliation(s)
- G M Hadjigeorgiou
- Department of Neurology, H. Houston Merritt Clinical Research Center for Muscular Dystrophy and Related Diseases, Columbia University College of Physicians and Surgeons, New York, NY, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
49
|
Morgan-Hughes JA, Hanna MG. Mitochondrial encephalomyopathies: the enigma of genotype versus phenotype. BIOCHIMICA ET BIOPHYSICA ACTA 1999; 1410:125-45. [PMID: 10076022 DOI: 10.1016/s0005-2728(98)00162-5] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Over the past decade a large body of evidence has accumulated implicating defects of human mitochondrial DNA in the pathogenesis of a group of disorders known collectively as the mitochondrial encephalomyopathies. Although impaired oxidative phosphorylation is likely to represent the final common pathway leading to cellular dysfunction in these diseases, fundamental issues still remain elusive. Perhaps the most challenging of these is to understand the mechanisms which underlie the complex relationship between genotype and phenotype. Here we examine this relationship and discuss some of the factors which are likely to be involved.
Collapse
Affiliation(s)
- J A Morgan-Hughes
- University Department of Clinical Neurology, Institute of Neurology, Queen Square, London WC1H 3BG, UK
| | | |
Collapse
|
50
|
Marin-Garcia J, Ananthakrishnan R, Goldenthal MJ, Filiano JJ, Perez-Atayde A. Mitochondrial dysfunction in skeletal muscle of children with cardiomyopathy. Pediatrics 1999; 103:456-9. [PMID: 9925841 DOI: 10.1542/peds.103.2.456] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
OBJECTIVES This study sought to examine skeletal muscle of children with cardiomyopathy (CM) for changes in mitochondrial enzyme activities and in mitochondrial DNA (mtDNA). BACKGROUND Heart mitochondrial enzymatic activity defects have been often found in dilated and hypertrophic CM. The defects primarily involve the activities of the electron transport system and oxidative phosphorylation pathway including respiratory complexes I, III, IV, and V. METHODS Skeletal muscle biopsies of 8 children with CM were examined for specific mitochondrial enzyme activities, mtDNA copy number and the presence of pathogenic mutations and deletions in mtDNA. RESULTS A marked deficiency in specific mitochondrial enzyme activities was found in 6 of 8 patients in skeletal muscle as well as in 2 of 3 hearts of those in whom cardiac tissue was available. Specific activity defects were found in complex I (2 cases), complex III (5 cases), complex IV (3 cases), and complex V (4 cases). Complex II and citrate synthase activities were unaffected. None of the previously reported pathogenic mutations associated with CM were detected, nor was there any evidence of mtDNA depletion. The incidence of defective respiratory complex activities in skeletal muscle was similar to the incidence of defective complex activities previously reported in cardiac tissue. CONCLUSIONS Mitochondrial analysis of skeletal muscle is warranted in the overall clinical evaluation of children with CM, and particularly before consideration for cardiac transplantation.
Collapse
Affiliation(s)
- J Marin-Garcia
- The Molecular Cardiology Institute, Highland Park, New Jersey 08904, USA
| | | | | | | | | |
Collapse
|