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Vodičková A, Koren SA, Wojtovich AP. Site-specific mitochondrial dysfunction in neurodegeneration. Mitochondrion 2022; 64:1-18. [PMID: 35182728 PMCID: PMC9035127 DOI: 10.1016/j.mito.2022.02.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 01/18/2022] [Accepted: 02/14/2022] [Indexed: 02/07/2023]
Abstract
Mitochondria are essential for neuronal survival and mitochondrial dysfunction is a hallmark of neurodegeneration. The loss in mitochondrial energy production, oxidative stress, and changes in calcium handling are associated with neurodegenerative diseases; however, different sites and types of mitochondrial dysfunction are linked to distinct neuropathologies. Understanding the causal or correlative relationship between changes in mitochondria and neuropathology will lead to new therapeutic strategies. Here, we summarize the evidence of site-specific mitochondrial dysfunction and mitochondrial-related clinical trials for neurodegenerative diseases. We further discuss potential therapeutic approaches, such as mitochondrial transplantation, restoration of mitochondrial function, and pharmacological alleviation of mitochondrial dysfunction.
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Affiliation(s)
- Anežka Vodičková
- Department of Anesthesiology and Perioperative Medicine, University of Rochester Medical Center, Rochester, NY, USA.
| | - Shon A Koren
- Department of Anesthesiology and Perioperative Medicine, University of Rochester Medical Center, Rochester, NY, USA.
| | - Andrew P Wojtovich
- Department of Anesthesiology and Perioperative Medicine, University of Rochester Medical Center, Rochester, NY, USA; Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY, USA.
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Hedberg-Oldfors C, Lindgren U, Basu S, Visuttijai K, Lindberg C, Falkenberg M, Larsson Lekholm E, Oldfors A. Mitochondrial DNA variants in inclusion body myositis characterized by deep sequencing. Brain Pathol 2021; 31:e12931. [PMID: 33354847 PMCID: PMC8412083 DOI: 10.1111/bpa.12931] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 12/11/2020] [Accepted: 12/21/2020] [Indexed: 01/22/2023] Open
Abstract
Muscle pathology in inclusion body myositis (IBM) typically includes inflammatory cell infiltration, muscle fibers with rimmed vacuoles and cytochrome c oxidase (COX)‐deficient fibers. Previous studies have revealed clonal expansion of large mitochondrial DNA (mtDNA) deletions in the COX‐deficient muscle fibers. Technical limitations have prevented complete investigations of the mtDNA deletions and other mtDNA variants. Detailed characterization by deep sequencing of mtDNA in muscle samples from 21 IBM patients and 10 age‐matched controls was performed after whole genome sequencing with a mean depth of mtDNA coverage of 46,000x. Multiple large mtDNA deletions and duplications were identified in all IBM and control muscle samples. In general, the IBM muscles demonstrated a larger number of deletions and duplications with a mean heteroplasmy level of 10% (range 1%‐35%) compared to controls (1%, range 0.2%‐3%). There was also a small increase in the number of somatic single nucleotide variants in IBM muscle. More than 200 rearrangements were recurrent in at least two or more IBM muscles while 26 were found in both IBM and control muscles. The deletions and duplications, with a high recurrence rate, were mainly observed in three mtDNA regions, m.534‐4429, m.6330‐13993, and m.8636‐16072, where some were flanked by repetitive sequences. The mtDNA copy number in IBM muscle was reduced to 42% of controls. Immunohistochemical and western blot analyses of IBM muscle revealed combined complex I and complex IV deficiency affecting the COX‐deficient fibers. In conclusion, deep sequencing and quantitation of mtDNA variants revealed that IBM muscles had markedly increased levels of large deletions and duplications, and there were also indications of increased somatic single nucleotide variants and reduced mtDNA copy numbers compared to age‐matched controls. The distribution and type of variants were similar in IBM muscle and controls indicating an accelerated aging process in IBM muscle, possibly associated with chronic inflammation.
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Affiliation(s)
| | - Ulrika Lindgren
- Department of Laboratory Medicine, University of Gothenburg, Gothenburg, Sweden.,Neuromuscular Centre, Department of Neurology, Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Swaraj Basu
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Gothenburg, Sweden
| | | | - Christopher Lindberg
- Neuromuscular Centre, Department of Neurology, Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Maria Falkenberg
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Gothenburg, Sweden
| | - Erik Larsson Lekholm
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Gothenburg, Sweden
| | - Anders Oldfors
- Department of Laboratory Medicine, University of Gothenburg, Gothenburg, Sweden
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Rygiel KA, Dodds RM, Patel HP, Syddall HE, Westbury LD, Granic A, Cooper C, Cliff J, Rocha MC, Turnbull DM, Sayer AA. Mitochondrial respiratory chain deficiency in older men and its relationship with muscle mass and performance. JCSM CLINICAL REPORTS 2017. [DOI: 10.17987/jcsm-cr.v2i2.35] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
IntroductionSarcopenia is the loss of muscle mass and physical performance with age, and recognition of its importance in clinical practice is growing. Age-related decline in muscle mitochondrial function has been described although less is known about the role of mitochondrial dysfunction in sarcopenia. The aim of this study was to investigate whether respiratory chain deficiency is associated with muscle mass and physical performance among a sample of healthy older men participating in the Hertfordshire Sarcopenia Study.MethodsWe used immunofluorescence on biopsies of the vastus lateralis to measure levels of the NDUFB8 subunit of complex I and the COX-1 subunit of complex IV per fibre. We measured muscle mass using dual-energy x-ray absorptiometry. We assessed physical performance using grip strength, gait speed, chair rise time, timed up and go and standing balance time, and composed an aggregate performance score on the scale of 0 (worst) and 5 (best performance). We used linear regression with a cluster sandwich estimator to test relationships between complex I / IV and muscle mass / physical performance. Study approval was granted by the Hertfordshire Research Ethics Committee.ResultsSamples were available from 77 participants of mean age 72.6 (2.5) years. The median number of fibres analysed per participant was 157 (104, 237). We expressed complex I and IV levels as Z-scores relative to that expected in young controls. The overall participant mean Z-scores were 0.3 (1.3) and -1.5 (0.9) for complex I and IV, respectively. We saw no relationship between complex I or IV and muscle mass. Each unit (SD) increase in complex I was associated with an increase in aggregate performance score of 0.06 (95% CI: 0.02, 0.09, P = 0.003), whilst the relationship for complex IV did not reach significance.ConclusionWe saw marked heterogeneity in complex I and IV levels, both between and within participants, as well as lower overall levels of complex IV. The finding of a small but statistically significant positive association between complex I levels and physical performance suggests that mitochondrial dysfunction may have a role in the development of sarcopenia. These findings will help inform the design of future studies across a wider range of ages and in both women and men.
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Phadke R. Myopathology of Adult and Paediatric Mitochondrial Diseases. J Clin Med 2017; 6:jcm6070064. [PMID: 28677615 PMCID: PMC5532572 DOI: 10.3390/jcm6070064] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Revised: 06/21/2017] [Accepted: 06/28/2017] [Indexed: 01/09/2023] Open
Abstract
Mitochondria are dynamic organelles ubiquitously present in nucleated eukaryotic cells, subserving multiple metabolic functions, including cellular ATP generation by oxidative phosphorylation (OXPHOS). The OXPHOS machinery comprises five transmembrane respiratory chain enzyme complexes (RC). Defective OXPHOS gives rise to mitochondrial diseases (mtD). The incredible phenotypic and genetic diversity of mtD can be attributed at least in part to the RC dual genetic control (nuclear DNA (nDNA) and mitochondrial DNA (mtDNA)) and the complex interaction between the two genomes. Despite the increasing use of next-generation-sequencing (NGS) and various omics platforms in unravelling novel mtD genes and pathomechanisms, current clinical practice for investigating mtD essentially involves a multipronged approach including clinical assessment, metabolic screening, imaging, pathological, biochemical and functional testing to guide molecular genetic analysis. This review addresses the broad muscle pathology landscape including genotype–phenotype correlations in adult and paediatric mtD, the role of immunodiagnostics in understanding some of the pathomechanisms underpinning the canonical features of mtD, and recent diagnostic advances in the field.
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Affiliation(s)
- Rahul Phadke
- Division of Neuropathology, UCL Institute of Neurology, National Hospital for Neurology and Neurosurgery, UCLH NHS Foundation Trust, London WC1N 3BG, UK.
- Dubowitz Neuromuscular Centre, Great Ormond Street Hospital for Children NHS Foundation Trust, London WC1N 3JH, UK.
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Cheema N, Herbst A, McKenzie D, Aiken JM. Apoptosis and necrosis mediate skeletal muscle fiber loss in age-induced mitochondrial enzymatic abnormalities. Aging Cell 2015; 14:1085-93. [PMID: 26365892 PMCID: PMC4693455 DOI: 10.1111/acel.12399] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/20/2015] [Indexed: 01/07/2023] Open
Abstract
Sarcopenia, the age‐induced loss of skeletal muscle mass and function, results from the contributions of both fiber atrophy and loss of myofibers. We have previously characterized sarcopenia in FBN rats, documenting age‐dependent declines in muscle mass and fiber number along with increased fiber atrophy and fibrosis in vastus lateralis and rectus femoris muscles. Concomitant with these sarcopenic changes is an increased abundance of mitochondrial DNA deletion mutations and electron transport chain (ETC) abnormalities. In this study, we used immunohistological and histochemical approaches to define cell death pathways involved in sarcopenia. Activation of muscle cell death pathways was age‐dependent with most apoptotic and necrotic muscle fibers exhibiting ETC abnormalities. Although activation of apoptosis was a prominent feature of electron transport abnormal muscle fibers, necrosis was predominant in atrophic and broken ETC‐abnormal fibers. These data suggest that mitochondrial dysfunction is a major contributor to the activation of cell death processes in aged muscle fibers. The link between ETC abnormalities, apoptosis, fiber atrophy, and necrosis supports the hypothesis that mitochondrial DNA deletion mutations are causal in myofiber loss. These studies suggest a progression of events beginning with the generation and accumulation of a mtDNA deletion mutation, the concomitant development of ETC abnormalities, a subsequent triggering of apoptotic and, ultimately, necrotic events resulting in muscle fiber atrophy, breakage, and fiber loss.
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Affiliation(s)
- Nashwa Cheema
- Department of Biological Sciences Centre for Prions and Protein Folding Diseases University of Alberta Edmonton AB Canada
| | - Allen Herbst
- Department of Agricultural Food and Nutritional Sciences Centre for Prions and Protein Folding Diseases University of Alberta Edmonton AB Canada
| | - Debbie McKenzie
- Department of Biological Sciences Centre for Prions and Protein Folding Diseases University of Alberta Edmonton AB Canada
| | - Judd M. Aiken
- Department of Agricultural Food and Nutritional Sciences Centre for Prions and Protein Folding Diseases University of Alberta Edmonton AB Canada
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Context-Dependent Role of Mitochondrial Fusion-Fission in Clonal Expansion of mtDNA Mutations. PLoS Comput Biol 2015; 11:e1004183. [PMID: 25996936 PMCID: PMC4440705 DOI: 10.1371/journal.pcbi.1004183] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Accepted: 02/09/2015] [Indexed: 12/14/2022] Open
Abstract
The accumulation of mutant mitochondrial DNA (mtDNA) molecules in aged cells has been associated with mitochondrial dysfunction, age-related diseases and the ageing process itself. This accumulation has been shown to often occur clonally, where mutant mtDNA grow in number and overpopulate the wild-type mtDNA. However, the cell possesses quality control (QC) mechanisms that maintain mitochondrial function, in which dysfunctional mitochondria are isolated and removed by selective fusion and mitochondrial autophagy (mitophagy), respectively. The aim of this study is to elucidate the circumstances related to mitochondrial QC that allow the expansion of mutant mtDNA molecules. For the purpose of the study, we have developed a mathematical model of mitochondrial QC process by extending our previous validated model of mitochondrial turnover and fusion-fission. A global sensitivity analysis of the model suggested that the selectivity of mitophagy and fusion is the most critical QC parameter for clearing de novo mutant mtDNA molecules. We further simulated several scenarios involving perturbations of key QC parameters to gain a better understanding of their dynamic and synergistic interactions. Our model simulations showed that a higher frequency of mitochondrial fusion-fission can provide a faster clearance of mutant mtDNA, but only when mutant–rich mitochondria that are transiently created are efficiently prevented from re-fusing with other mitochondria and selectively removed. Otherwise, faster fusion-fission quickens the accumulation of mutant mtDNA. Finally, we used the insights gained from model simulations and analysis to propose a possible circumstance involving deterioration of mitochondrial QC that permits mutant mtDNA to expand with age. Mitochondria are responsible for most energy generation in human and animal cells. Loss or pathological alteration of mitochondrial function is a hallmark of many age-related diseases. Mitochondrial dysfunction may be a central and conserved feature of the ageing process. As part of quality control (QC), mitochondria are continually replicated and degraded. Furthermore, two mitochondria can fuse to form a single mitochondrion, and a mitochondrion can divide (fission) into two separate organelles. Despite this QC, mutant mitochondrial DNA (mtDNA) molecules have been observed to accumulate in cells with age which may lead to mitochondrial dysfunction. In this study, we created a detailed mathematical model of mitochondrial QC and performed model simulations to investigate circumstances allowing or preventing the accumulation of mutant mtDNA. We found that more frequent fusion-fission could quicken mutant mtDNA clearance, but only when mitochondria harboring a high fraction of mutant molecules were strongly prevented from fusing with other mitochondria and selectively degraded. Otherwise, faster fusion-fission would actually enhance the accumulation of mutant mtDNA. Our results suggested that the expansion of mutant mtDNA likely involves a decline in the selectivity of mitochondrial degradation and fusion. This insight might open new avenues for experiment and possible development of future therapies.
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Carelli V, Maresca A, Caporali L, Trifunov S, Zanna C, Rugolo M. Mitochondria: Biogenesis and mitophagy balance in segregation and clonal expansion of mitochondrial DNA mutations. Int J Biochem Cell Biol 2015; 63:21-4. [PMID: 25666555 DOI: 10.1016/j.biocel.2015.01.023] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Revised: 01/20/2015] [Accepted: 01/29/2015] [Indexed: 12/31/2022]
Abstract
Mitochondria are cytoplasmic organelles containing their own multi-copy genome. They are organized in a highly dynamic network, resulting from balance between fission and fusion, which maintains homeostasis of mitochondrial mass through mitochondrial biogenesis and mitophagy. Mitochondrial DNA (mtDNA) mutates much faster than nuclear DNA. In particular, mtDNA point mutations and deletions may occur somatically and accumulate with aging, coexisting with the wild type, a condition known as heteroplasmy. Under specific circumstances, clonal expansion of mutant mtDNA may occur within single cells, causing a wide range of severe human diseases when mutant overcomes wild type. Furthermore, mtDNA deletions accumulate and clonally expand as a consequence of deleterious mutations in nuclear genes involved in mtDNA replication and maintenance, as well as in mitochondrial fusion genes (mitofusin-2 and OPA1), possibly implicating mtDNA nucleoids segregation. We here discuss how the intricacies of mitochondrial homeostasis impinge on the intracellular propagation of mutant mtDNA. This article is part of a Directed Issue entitled: Energy Metabolism Disorders and Therapies.
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Affiliation(s)
- Valerio Carelli
- IRCCS Institute of Neurological Sciences of Bologna, Bellaria Hospital, Bologna, Italy; Unit of Neurology, Department of Biomedical and NeuroMotor Sciences (DIBINEM), University of Bologna, Bologna, Italy.
| | - Alessandra Maresca
- IRCCS Institute of Neurological Sciences of Bologna, Bellaria Hospital, Bologna, Italy; Unit of Neurology, Department of Biomedical and NeuroMotor Sciences (DIBINEM), University of Bologna, Bologna, Italy
| | - Leonardo Caporali
- IRCCS Institute of Neurological Sciences of Bologna, Bellaria Hospital, Bologna, Italy; Unit of Neurology, Department of Biomedical and NeuroMotor Sciences (DIBINEM), University of Bologna, Bologna, Italy
| | - Selena Trifunov
- Unit of Neurology, Department of Biomedical and NeuroMotor Sciences (DIBINEM), University of Bologna, Bologna, Italy; Unit of Cellular Biochemistry, Department of Pharmacy and Biotechnology, University of Bologna, Bologna, Italy
| | - Claudia Zanna
- IRCCS Institute of Neurological Sciences of Bologna, Bellaria Hospital, Bologna, Italy; Unit of Cellular Biochemistry, Department of Pharmacy and Biotechnology, University of Bologna, Bologna, Italy
| | - Michela Rugolo
- Unit of Cellular Biochemistry, Department of Pharmacy and Biotechnology, University of Bologna, Bologna, Italy
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Al-Sarraj S, King A, Cleveland M, Pradat PF, Corse A, Rothstein JD, Leigh PN, Abila B, Bates S, Wurthner J, Meininger V. Mitochondrial abnormalities and low grade inflammation are present in the skeletal muscle of a minority of patients with amyotrophic lateral sclerosis; an observational myopathology study. Acta Neuropathol Commun 2014; 2:165. [PMID: 25510661 PMCID: PMC4297389 DOI: 10.1186/s40478-014-0165-z] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Accepted: 11/23/2014] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Amyotrophic lateral sclerosis (ALS) is a primary progressive neurodegenerative disease characterised by neuronal loss of lower motor neurons (in the spinal cord and brainstem) and/or upper motor neurons (in the motor cortex) and subsequent denervation atrophy of skeletal muscle. AIM A comprehensive examination of muscle pathology from a cohort of clinically confirmed ALS patients, including an investigation of inflammation, complement activation, and deposition of abnormal proteins in order to compare them with findings from an age-matched, control group. MATERIAL AND METHODS 31 muscle biopsies from clinically confirmed ALS patients and 20 normal controls underwent a comprehensive protocol of histochemical and immunohistochemical stains, including HLA-ABC, C5b-9, p62, and TDP-43. RESULTS Neurogenic changes were confirmed in 30/31 ALS cases. In one case, no neurogenic changes could be detected. Muscle fibre necrosis was seen in 5/31 cases and chronic mononuclear inflammatory cell infiltration in 5/31 (2 of them overlapped with those showing muscle necrosis). In four biopsies there was an increase in the proportion of cytochrome oxidase (COX) negative fibres (2-3%). p62 faintly stained cytoplasmic bodies in eight cases and none were immunoreactive to TDP-43. CONCLUSION This large series of muscle biopsies from patients with ALS demonstrates neurogenic atrophy is a nearly uniform finding and that mild mitochondrial abnormalities and low-grade inflammation can be seen and do not rule out the diagnosis of ALS. These findings could lend support to the notion that ALS is a complex and heterogeneous disorder.
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Affiliation(s)
- Safa Al-Sarraj
- Neuropathology, Neuroscience Academic Building, Kings College Hospital, Denmark Hill, London, SE5 9RS, UK.
| | - Andrew King
- Neuropathology, Neuroscience Academic Building, Kings College Hospital, Denmark Hill, London, SE5 9RS, UK.
| | | | - Pierre-François Pradat
- Département des Maladies du Système Nerveux, APHP, Reseau SLA IDF Groupe Hospitalier Pitié-Salpêtrière, Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Laboratoire d'Imagerie Biomédicale (LIB), Paris, F-75005, France.
| | - Andrea Corse
- Department of Neurology, Johns Hopkins School of Medicine, 1800 Orleans Street, Baltimore, MD, USA.
| | - Jeffrey D Rothstein
- Department of Neurology, Johns Hopkins School of Medicine, 1800 Orleans Street, Baltimore, MD, USA.
| | - Peter Nigel Leigh
- Division of Medicine (Neurology), Brighton and Sussex Medical School, Trafford Centre for biomedical Research, Falmer, Brighton, BN1 9RY, UK.
| | - Bams Abila
- Biopharm Translational Medicine, GSK, Stevenage, UK.
| | - Stewart Bates
- Biopharm Translational Medicine, GSK, Stevenage, UK.
| | - Jens Wurthner
- Novartis Oncology Translational Medicine, Basel, Switzerland.
| | - Vincent Meininger
- Département des Maladies du Système Nerveux, APHP, Reseau SLA IDF Groupe Hospitalier Pitié-Salpêtrière, Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Laboratoire d'Imagerie Biomédicale (LIB), Paris, F-75005, France.
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Al-Sarraj S, King A, Cleveland M, Pradat PF, Corse A, Rothstein JD, Leigh PN, Abila B, Bates S, Wurthner J, Meininger V. Mitochondrial abnormalities and low grade inflammation are present in the skeletal muscle of a minority of patients with amyotrophic lateral sclerosis; an observational myopathology study. Acta Neuropathol Commun 2014. [DOI: 10.1186/s40478-014-0165-z s40478-014-0165-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
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Khrapko K, Turnbull D. Mitochondrial DNA mutations in aging. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2014; 127:29-62. [PMID: 25149213 DOI: 10.1016/b978-0-12-394625-6.00002-7] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The relationship of mitochondrial DNA mutations to aging is still debated. Most mtDNA mutations are recessive: there are multiple copies per cell and mutation needs to clonally expand to cause respiratory deficiency. Overall mtDNA mutant loads are low, so effects of mutations are limited to critical areas where mutations locally reach high fractions. This includes respiratory chain deficient zones in muscle fibers, respiratory-deficient crypts in colon, and massive expansions of deleted mtDNA in substantia nigra neurons. mtDNA "mutator" mouse with increased rate of mtDNA mutations is a useful model, although rates and distribution of mutations may significantly deviate from what is observed in human aging. Comparison of species with different longevity reveals intriguing longevity-related traits in mtDNA sequence, although their significance is yet to be evaluated. The impact of somatic mtDNA mutations rapidly increases with age, so their importance is expected to grow as human life expectancy increases.
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Affiliation(s)
- Konstantin Khrapko
- Harvard Medical School, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA
| | - Doug Turnbull
- LLHW Centre for Ageing and Vitality, Newcastle University, Newcastle, United Kingdom
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Tam ZY, Gruber J, Halliwell B, Gunawan R. Mathematical modeling of the role of mitochondrial fusion and fission in mitochondrial DNA maintenance. PLoS One 2013; 8:e76230. [PMID: 24146842 PMCID: PMC3795767 DOI: 10.1371/journal.pone.0076230] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2013] [Accepted: 08/21/2013] [Indexed: 11/29/2022] Open
Abstract
Accumulation of mitochondrial DNA (mtDNA) mutations has been implicated in a wide range of human pathologies, including neurodegenerative diseases, sarcopenia, and the aging process itself. In cells, mtDNA molecules are constantly turned over (i.e. replicated and degraded) and are also exchanged among mitochondria during the fusion and fission of these organelles. While the expansion of a mutant mtDNA population is believed to occur by random segregation of these molecules during turnover, the role of mitochondrial fusion-fission in this context is currently not well understood. In this study, an in silico modeling approach is taken to investigate the effects of mitochondrial fusion and fission dynamics on mutant mtDNA accumulation. Here we report model simulations suggesting that when mitochondrial fusion-fission rate is low, the slow mtDNA mixing can lead to an uneven distribution of mutant mtDNA among mitochondria in between two mitochondrial autophagic events leading to more stochasticity in the outcomes from a single random autophagic event. Consequently, slower mitochondrial fusion-fission results in higher variability in the mtDNA mutation burden among cells in a tissue over time, and mtDNA mutations have a higher propensity to clonally expand due to the increased stochasticity. When these mutations affect cellular energetics, nuclear retrograde signalling can upregulate mtDNA replication, which is expected to slow clonal expansion of these mutant mtDNA. However, our simulations suggest that the protective ability of retrograde signalling depends on the efficiency of fusion-fission process. Our results thus shed light on the interplay between mitochondrial fusion-fission and mtDNA turnover and may explain the mechanism underlying the experimentally observed increase in the accumulation of mtDNA mutations when either mitochondrial fusion or fission is inhibited.
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Affiliation(s)
- Zhi Yang Tam
- Institute for Chemical and Bioengineering, ETH Zurich, Zurich, Switzerland
| | - Jan Gruber
- Department of Biochemistry, Centre for Life Sciences, National University of Singapore, Singapore, Singapore
| | - Barry Halliwell
- Department of Biochemistry, Centre for Life Sciences, National University of Singapore, Singapore, Singapore
| | - Rudiyanto Gunawan
- Institute for Chemical and Bioengineering, ETH Zurich, Zurich, Switzerland
- * E-mail:
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Karri B, Sebastian RT, Kyle G, Hart IK, Mountford RC. Ptosis as the Only Presenting Feature of a Mitochondrial Cytopathy. Neuroophthalmology 2011. [DOI: 10.3109/01658107.2011.615453] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Sleigh K, Ball S, Hilton DA. Quantification of changes in muscle from individuals with and without mitochondrial disease. Muscle Nerve 2011; 43:795-800. [PMID: 21607963 DOI: 10.1002/mus.21962] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
INTRODUCTION Muscle biopsy is used in the diagnosis of mitochondrial disorders. There are limited data on the normal ranges, so interpretation of findings can be difficult. METHODS We evaluated the percentage of fibers showing mitochondrial abnormalities using Gomori trichrome staining, succinate dehydrogenase, and cytochrome oxidase histochemistry in autopsy samples taken from 45 individuals without evidence of muscle disease and biopsies from 17 patients with mitochondrial disorders. RESULTS In controls, mitochondrial abnormalities were rare before the fifth decade, and most had <0.1% abnormal fibers. The proportion of abnormal fibers increased with age and was higher in deltoid than quadriceps. Most patients with mitochondrial disorders had >0.5% abnormal fibers. CONCLUSIONS Although some patients with mitochondrial disease have very few muscle fibers that show mitochondrial abnormalities, a rate of abnormality of >0.5% fibers, in the absence of a primary muscle disease this should raise the possibility of a mitochondrial disorder.
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Affiliation(s)
- Kerry Sleigh
- Department of Cellular and Anatomical Pathology, Derriford Hospital, Plymouth PL6 8DH, UK
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15
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Argov Z. Current approach to seronegative myasthenia. J Neurol 2010; 258:14-8. [PMID: 20852878 DOI: 10.1007/s00415-010-5746-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2010] [Accepted: 09/03/2010] [Indexed: 10/19/2022]
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Rajender S, Rahul P, Mahdi AA. Mitochondria, spermatogenesis and male infertility. Mitochondrion 2010; 10:419-28. [DOI: 10.1016/j.mito.2010.05.015] [Citation(s) in RCA: 105] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2010] [Revised: 05/24/2010] [Accepted: 05/28/2010] [Indexed: 11/30/2022]
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Karpati G, O'Ferrall EK. Sporadic inclusion body myositis: pathogenic considerations. Ann Neurol 2009; 65:7-11. [PMID: 19194875 DOI: 10.1002/ana.21622] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Sporadic inclusion body myositis is the commonest acquired disease of skeletal muscles after 50 years of age, and as such it has commanded a great deal of attention of investigators over the past 25 years. As a result, a large amount of information has accumulated concerning its clinical profile, myopathology, and immunopathology. In the myopathology and immunopathology, there is general agreement that the characteristic features could be divided into a degenerative and an inflammatory group. However, there has been controversy about the possible role of these changes in the pathogenesis of muscle fiber damage. In particular, there is no agreement whether a cause-and-effect relationship exists between these two groups of changes, and if so, which is the primary one. In this brief overview, we examine the validity of the various controversial observations and critically review the justification for the two major hypotheses for the primary role of inflammation versus degeneration.
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Affiliation(s)
- George Karpati
- Department of Neurology, McGill University, Montreal Neurological Institute, Montreal, Quebec, Canada.
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Khrapko K, Vijg J. Mitochondrial DNA mutations and aging: devils in the details? Trends Genet 2008; 25:91-8. [PMID: 19110336 DOI: 10.1016/j.tig.2008.11.007] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2008] [Revised: 11/14/2008] [Accepted: 11/24/2008] [Indexed: 01/07/2023]
Abstract
Although several lines of evidence support a role for accumulating somatic mitochondrial DNA (mtDNA) mutations in the etiology of aging, it remains unclear if they are a major cause of age-related deterioration and death. Mouse models that harbor elevated mtDNA mutation frequencies age prematurely; these findings were thought to provide conclusive evidence for a causal role of such mutations in aging. Yet, the presence of several conflicting reports has sparked controversy in the field and this is further aggravated by discrepancies in the estimates of mtDNA mutant fractions, which disagree by orders of magnitude. Here, we briefly review the evidence and some of the unresolved questions surrounding a causative role for accumulating mtDNA mutations in aging.
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Affiliation(s)
- Konstantin Khrapko
- Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA 02115, USA.
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19
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Jeppesen TD, Quistorff B, Wibrand F, Vissing J. 31P-MRS of skeletal muscle is not a sensitive diagnostic test for mitochondrial myopathy. J Neurol 2007; 254:29-37. [PMID: 17278044 DOI: 10.1007/s00415-006-0229-5] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2005] [Accepted: 03/15/2006] [Indexed: 11/25/2022]
Abstract
Clinical phenotypes of persons with mitochondrial DNA (mtDNA) mutations vary considerably. Therefore, diagnosing mitochondrial myopathy (MM) patients can be challenging and warrants diagnostic guidelines. (31)phosphorous magnetic resonance spectroscopy ((31)P-MRS) have been included as a minor diagnostic criterion for MM but the diagnostic strength of this test has not been compared with that of other commonly used diagnostic procedures for MM. To investigate this, we studied seven patients with single, large-scale deletions-, nine with point mutations of mtDNA and 14 healthy subjects, who were investigated for the following: 1) (31)P-MRS of lower arm and leg muscles before and after exercise, 2) resting and peak-exercise induced increases of plasma lactate, 3) muscle morphology and -mitochondrial enzyme activity, 4) maximal oxygen uptake (VO(2max)), 5) venous oxygen desaturation during handgrip exercise and 6) a neurological examination. All MM patients had clinical symptoms of MM, > 2% ragged red fibers in muscle, and impaired oxygen desaturation during handgrip. Fourteen of 16 patients had impaired VO(2max), 10/16 had elevated resting plasma lactate, and 10/11 that were investigated had impaired citrate synthase-corrected complex I activity. Resting PCr/P(i) ratio and leg P(i) recovery were lower in MM patients vs. healthy subjects. PCr and ATP production after exercise were similar in patients and healthy subjects. Although the specificity for MM of some (31)P-MRS variables was as high as 100%, the sensitivity was low (0-63%) and the diagnostic strength of (31)P-MRS was inferior to the other diagnostic tests for MM. Thus, (31)P-MRS should not be a routine test for MM, but may be an important research tool.
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Affiliation(s)
- Tina Dysgaard Jeppesen
- Neuromuscular Research Unit, Section 7611, National University Hospital, Rigshospitalet, Blegdamsvej 9, 2100, Copenhagen, Denmark.
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20
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Debray FG, Drouin E, Herzog D, Lortie A, Lambert M, Garel L, Mitchell GA, Michaud JL. Recurrent pancreatitis in mitochondrial cytopathy. Am J Med Genet A 2007; 140:2330-5. [PMID: 17022070 DOI: 10.1002/ajmg.a.31457] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Diabetes mellitus and exocrine insufficiency are the commonest pancreatic manifestations of mitochondrial diseases. In contrast, pancreatitis has rarely been described in mitochondrial syndromes. We report on a patient with Kearns-Sayre syndrome and recurrent episodes of acute pancreatitis for which no explanation could be found other than the associated mitochondrial dysfunction. Interestingly, pharmacological disruption of mitochondrial metabolism in various models as well as in patients can cause pancreatitis, further supporting this association. A diagnosis of pancreatitis should be considered in any patients with mitochondrial disease and recurrent abdominal pain.
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21
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Oldfors A, Tulinius M. Mitochondrial encephalomyopathies. HANDBOOK OF CLINICAL NEUROLOGY 2007; 86:125-165. [PMID: 18808998 DOI: 10.1016/s0072-9752(07)86006-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
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22
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23
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Poe BG, Navratil M, Arriaga EA. Absolute quantitation of a heteroplasmic mitochondrial DNA deletion using a multiplex three-primer real-time PCR assay. Anal Biochem 2006; 362:193-200. [PMID: 17270140 PMCID: PMC1853271 DOI: 10.1016/j.ab.2006.12.035] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2006] [Revised: 12/08/2006] [Accepted: 12/18/2006] [Indexed: 01/07/2023]
Abstract
Quantitation of wild-type and deleted mitochondrial DNA (mtDNA) coexisting within the same cell (a.k.a., heteroplasmy) is important in mitochondrial disease and aging. We report the development of a multiplex three-primer PCR assay that is capable of absolute quantitation of wild-type and deleted mtDNA simultaneously. Molecular beacons were designed to hybridize with either type of mtDNA molecule, allowing real-time detection during PCR amplification. The assay is specific and can detect down to six copies of mtDNA, making it suitable for single-cell analyses. The relative standard deviation in the threshold cycle number is approximately 0.6%. Heteroplasmy was quantitated in individual cytoplasmic hybrid cells (cybrids), containing a large mtDNA deletion, and bulk cell samples. Individual cybrid cells contained 100-2600 copies of wild-type mtDNA and 950-4700 copies of deleted mtDNA, and the percentage of heteroplasmy ranged from 43+/-16 to 95+/-16%. The average amount of total mtDNA was 3800+/-1600 copies/cybrid cell, and the average percentage of heteroplasmy correlated well with the bulk cell sample. The single-cell analysis also revealed that heteroplasmy in individual cells is highly heterogeneous. This assay will be useful for monitoring clonal expansions of mtDNA deletions and investigating the role of heteroplasmy in cell-to-cell heterogeneity in cellular models of mitochondrial disease and aging.
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Affiliation(s)
| | | | - Edgar A. Arriaga
- *To whom all correspondence should be addressed: Tel. (612) 624-8024, fax (612) 626-7541,
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24
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Gupta S, Blaivas M, Ike RW, Crofford LJ. Polymyositis evolving after rhabdomyolysis associated with HMG-CoA reductase inhibitors: a report of two cases. J Clin Rheumatol 2006; 7:332-5. [PMID: 17039165 DOI: 10.1097/00124743-200110000-00015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
3-Hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors are commonly used for treatment of hyperlipidemia and its deleterious effects. Myotoxicity has been associated with use of these agents. We report two cases of inflammatory myopathy in patients receiving these agents that did not respond to drug withdrawal and required immunosuppressive treatment. One of these patients developed an antibody to histidyl tRNA synthetase or Jo-1, an autoantibody associated with idiopathic inflammatory myopathies. We suggest that HMG-CoA reductase inhibitor-associated myotoxicity may trigger an immune-mediated inflammatory myopathy. Patients whose muscle abnormalities do not resolve with drug withdrawal should be considered for muscle biopsy.
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Affiliation(s)
- S Gupta
- Department of Internal Medicine, Division of Rheumatology, University of Michigan Medical Center, Ann Arbor, Michigan 48109, USA
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Rostedt Punga A, Ahlqvist K, Bartoccioni E, Scuderi F, Marino M, Suomalainen A, Kalimo H, Stålberg EV. Neurophysiological and mitochondrial abnormalities in MuSK antibody seropositive myasthenia gravis compared to other immunological subtypes. Clin Neurophysiol 2006; 117:1434-43. [PMID: 16737845 DOI: 10.1016/j.clinph.2006.03.028] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2005] [Revised: 03/21/2006] [Accepted: 03/30/2006] [Indexed: 11/19/2022]
Abstract
OBJECTIVE To compare the electrophysiological and histopathological features of immunological myasthenia gravis (MG) subtypes. METHODS Fifty MG patients underwent clinical examination, MuSK-Ab and AChR-Ab analysis. The majority underwent quantitative and single-fiber electromyography (QEMG, SFEMG), repetitive nerve stimulation and deltoid muscle biopsy. From muscle specimens with histological mitochondrial dysfunction, we amplified mitochondrial DNA (mtDNA). In specimens with mtDNA deletions, the nuclear gene POLG1 was sequenced. RESULTS Five AChR-Ab seropositive [AChR(+)] and 5 seronegative [AChR(-)] patients were MuSK-Ab seropositive [MuSK(+)]. Five of 7 neurophysiologically examined MuSK(+) patients (71%) had proximal myopathic pattern, compared to 7 of 31 MuSK(-)/AChR(+) patients (23%) (P=0.012). SFEMG was abnormal in all examined MuSK(+) patients. All 7 biopsied MuSK(+) and 32 MuSK(-) patients (89%) had cytochrome c oxidase (COX) negative fibers. Three of five MuSK(+) and 13 of 20 MuSK(-) patients analyzed had multiple mtDNA deletions but no POLG1 mutations. CONCLUSIONS Similar degree of SFEMG abnormalities was present in proximal muscles among MuSK(+) and AChR(+) patients. Proximal myopathy was over-represented in MuSK(+) patients; however, both MuSK(+) and MuSK(-) patients had mild myopathy with frequent mitochondrial abnormalities. SIGNIFICANCE The weakness in MuSK(+) patients is most likely due to disturbed neuromuscular transmission. The frequently encountered mitochondrial dysfunction in MG warrants further study.
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Affiliation(s)
- A Rostedt Punga
- Department of Clinical Neurophysiology, University Hospital, S-75185 Uppsala, Sweden.
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Abstract
Symmetric proximal muscle weakness has many potential etiologies. An onset over weeks to months and elevated serum levels of muscle enzymes point to the diagnosis of an idiopathic inflammatory myopathy, including dermatomyositis, polymyositis, and inclusion body myositis. However, there is a broad differential diagnosis, including certain muscular dystrophies, metabolic myopathies, drug- or toxin-induced myotoxicity, neuropathies, and infectious myositides. The differentiation is critical for defining appropriate treatment. In addition, an alternative diagnosis may explain the lack of response to immunosuppressive treatment for some patients with polymyositis. Careful clinical evaluation and choice of available diagnostic tests are required to establish the correct diagnosis.
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Affiliation(s)
- Alan N Baer
- Department of Medicine, Division of Allergy, Immunology, and Rheumatology, School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Erie County Medical Center, 462 Grider Street, Buffalo, NY 14215, USA.
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Abstract
An expanding number of autosomal diseases has been associated with mitochondrial DNA (mtDNA) depletion and multiple deletions. These disorders have been classified as defects of intergenomic communication because mutations of the nuclear DNA are thought to disrupt the normal cross-talk that regulates the integrity and quantity of mtDNA. In 1989, autosomal dominant progressive external ophthalmoplegia with multiple deletions of mitochondrial DNA was the first of these disorders to be identified. Two years later, mtDNA depletion syndrome was initially reported in infants with severe hepatopathy or myopathy. The causes of these diseases are still unclear, but genetic linkage studies have identified three chromosomal loci for AD-PEO. Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE), an autosomal recessive disorder associated with both mtDNA depletion and multiple deletions, is now known to be due to loss-of-function mutations in the gene encoding thymidine phosphorylase. Increased plasma thymidine levels in MNGIE patients suggest that imbalanced nucleoside and nucleotide pools in mitochondria may lead to impaired replication of mtDNA. Future research will certainly lead to the identification of additional genetic causes of intergenomic communication defects and will likely provide insight into the normal "dialogue" between the two genomes.
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Affiliation(s)
- M Hirano
- Department of Neurology, College of Physicians & Surgeons, Columbia University, New York, NY 10032, USA
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Testa M, Navazio FM, Neugebauer J. Recognition, Diagnosis, and Treatment of Mitochondrial Myopathies in Endurance Athletes. Curr Sports Med Rep 2005; 4:282-7. [PMID: 16144587 DOI: 10.1097/01.csmr.0000306223.19714.7a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Endurance athletes complaining of muscle pains concomitant with fatigue and exercise intolerance provide a diagnostic challenge. When the most common causes have been ruled out, the presence of metabolic myopathies, including mitochondrial myopathies (MMs), should be considered. MMs are a group of diseases characterized by inadequate mitochondrial ATP production needed for the energetic requirement of the exercising muscles. Athletes with myalgia, fatigue, dyspnea, and muscular cramping should be questioned for history of rhabdomyolysis or myoglobinuria as well as detailed family history, given the predominant matrilinear inheritance of MMs. In all suspected cases, blood lactate and ventilatory response on effort plus muscle biopsy for histologic and molecular studies are recommended. Therapeutic recommendations consist of a set of instructions including genetic counseling, awareness of possible myoglobinuric episodes, and controlled exercise training.
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Affiliation(s)
- Massimo Testa
- Sports Performance Program, University of California, Davis Medical Center, Sacramento, CA 95816, USA.
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Abstract
Muscle biopsy provides the best tissue to confirm a mitochondrial cytopathy. Histochemical features often correlate with specific syndromes and facilitate the selection of biochemical and genetic studies. Ragged-red fibres nearly always indicate a combination defect of respiratory complexes I and IV. Increased punctate lipid within myofibers is a regular feature of Kearns-Sayre and PEO, but not of MELAS and MERRF. Total deficiency of succinate dehydrogenase indicates a severe defect in Complex II; total absence of cytochrome-c-oxidase activity in all myofibres correlates with a severe deficiency of Complex IV or of coenzyme-Q10. The selective loss of cytochrome-c-oxidase activity in scattered myofibers, particularly if accompanied by strong succinate dehydrogenase staining in these same fibres, is good evidence of mitochondrial cytopathy and often of a significant mtDNA mutation, though not specific for Complex IV disorders. Glycogen may be excessive in ragged-red zones. Ultrastructure provides morphological evidence of mitochondrial cytopathy, in axons and endothelial cells as well as myocytes. Abnormal axonal mitochondria may contribute to neurogenic atrophy of muscle, a secondary chronic feature. Quantitative determinations of respiratory chain enzyme complexes, with citrate synthase as an internal control, confirm the histochemical impressions or may be the only evidence of mitochondrial disease. Biological and technical artifacts may yield falsely low enzymatic activities. Genetic studies screen common point mutations in mtDNA. The brain exhibits characteristic histopathological alterations in mitochondrial diseases. Skin biopsy is useful for mitochondrial ultrastructure in smooth erector pili muscles and axons; skin fibroblasts may be grown in culture. Mitochondrial alterations occur in many nonmitochondrial diseases and also may be induced by drugs and toxins.
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Cormio A, Milella F, Vecchiet J, Felzani G, Gadaleta MN, Cantatore P. Mitochondrial DNA mutations in RRF of healthy subjects of different age. Neurobiol Aging 2005; 26:655-64. [PMID: 15708440 DOI: 10.1016/j.neurobiolaging.2004.06.014] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2004] [Revised: 06/11/2004] [Accepted: 06/29/2004] [Indexed: 11/18/2022]
Abstract
To obtain information on the mechanisms responsible of the generation of ragged red fibers (RRF) during aging, we analyzed the mitochondrial genotype of single skeletal muscle fibers of healthy individuals having an age comprised between 45 and 92 years. The sequencing of the D-loop region showed many sequence changes with respect to the Cambridge reference sequence (CRS), in both RRF and normal fibers. These changes were more abundant in RRF and their number increased between 50 and 60, and 61 and 70 years and then remained approximately constant. The analysis of the sequence changes showed that each subject contained one or more changes associated to RRF in positions of D-loop region that either do not change or that change very rarely. In general the same type of RRF-associated change was not found in more than one individual; exceptions were changes in positions 189, 295, 374 and 514, detected in 20-50% of analyzed subjects. In particular the A189G age-associated mutation was found only in old individuals and prevalently in RRF. Sequencing of other two mtDNA regions showed no relevant changes in the 16S/ND1 region and two RRF-associated original mutations, G5847A and A5884C, in two very conserved positions of tRNATyr. These results indicate that each subject has its own pattern of RRF-associated mutations in both coding and non-coding region of human mtDNA.
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Affiliation(s)
- Antonella Cormio
- Dipartimento di Biochimica e Biologia Molecolare, Università degli Studi di Bari, Via Orabona, 4, 70125 Bari, Italy
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31
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Drouet A. Comment organiser le bilan d’un syndrome d’intolérance musculaire à l’exercice (SIME) ? Rev Neurol (Paris) 2004; 160:1102-12. [PMID: 15602357 DOI: 10.1016/s0035-3787(04)71152-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- A Drouet
- Service de Neurologie, HIA Desgenettes, Lyon.
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Shao JY, Gao HY, Li YH, Zhang Y, Lu YY, Zeng YX. Quantitative detection of common deletion of mitochondrial DNA in hepatocellular carcinoma and hepatocellular nodular hyperplasia. World J Gastroenterol 2004; 10:1560-4. [PMID: 15162525 PMCID: PMC4572754 DOI: 10.3748/wjg.v10.i11.1560] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
AIM: To study the deletion of mitochondiral DNA in hepatocellular carcinoma and hepatocellular nodular hyperplasia and its significance in the development of cancer.
METHODS: Deleted mtDNA (CD-mtDNA) and wild type mtDNA (WT-mtDNA) were quantitatively analyzed by using real-time PCR in 27 hepatocellular carcinomas (HCC) and corresponding noncancerous liver tissues and 27 hepatocellular nodular hyperplasiae (HNH).
RESULTS: A novel CD (4981 bp) was detected in 85% (23/27) and 83% (22/27) of HCC and HNH tumor tissues, respectively, which were significantly higher than that in paired noncancerous liver tissues (57%, 15/27) (P < 0.05). The CD/WT-mtDNA ratio in HCC tumors was 0.00092 (median, interquartile range, 0.0001202 - 0.00105), which was significantly higher than that in paired noncancerous liver tissues (median, 0.000, quartile range, 0 - 0) (P = 0.002, Mann-Whitney Test), and was 25 of times of that in HNH tissues (median, 0.0000374, quartile range, 0 - 0.0004225) (P = 0.002, Mann-Whitney test).
CONCLUSION: CD-mtDNA mutation plays an important role in the development and progression of HCC.
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Affiliation(s)
- Jian-Yong Shao
- Department of Pathology, Cancer Center, Sun Yat-Sen University, Guangzhou 510060, Guangdong Province, China.
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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.
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Affiliation(s)
- Fazal Rahim
- From the Department of Neurology, University of Tennessee Health Science Center Memphis
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Thyagarajan D, Byrne E. Mitochondrial disorders of the nervous system: clinical, biochemical, and molecular genetic features. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2003; 53:93-144. [PMID: 12512338 DOI: 10.1016/s0074-7742(02)53005-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/28/2023]
Affiliation(s)
- Dominic Thyagarajan
- Department of Neurology, Flinders Medical Centre, Bedford Park, South Australia 5042, Australia
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35
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Khrapko K, Nekhaeva E, Kraytsberg Y, Kunz W. Clonal expansions of mitochondrial genomes: implications for in vivo mutational spectra. Mutat Res 2003; 522:13-9. [PMID: 12517407 DOI: 10.1016/s0027-5107(02)00306-8] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
It is often assumed mutant frequencies, as measured in a DNA sample, faithfully represent basic mutation rates associated with these mutations. This paradigm was extremely helpful for in vitro studies of the mechanisms of mutagenesis/repair and causes of mutations. However, in vivo, mutant fractions appear to vary dramatically and randomly from sample to sample. It's unlikely that basic mutational rates vary so much. Such variations are probably caused by clonal expansions of mutants within tissue. Whether a particular tissue sample includes an expansion or not, is a matter of chance, which explains the observed random fluctuations of mutant fractions. Well-known examples of clonal expansions involve pathological conditions such as cancer or mitochondrial disease. It is less appreciated that even in normal tissue, expansions of somatic mutants create local deviations from the "expected" mutant frequencies. The sizes of clonal expansions appear to span a wide range and thus, may affect samples of various sizes, from individual cells to individuals. In conclusion, human body appears to be a sort of a "gambling ground" for clonally expanding mutants. We speculate that expansion of early mutants rather than de novo mutation at old age may be the major source of at least some aging-specific mutants in our bodies.
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Affiliation(s)
- Konstantin Khrapko
- Gerontology Division, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA 02115, USA.
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36
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DiMauro S, Tanji K, Bonilla E, Pallotti F, Schon EA. Mitochondrial abnormalities in muscle and other aging cells: classification, causes, and effects. Muscle Nerve 2002; 26:597-607. [PMID: 12402281 DOI: 10.1002/mus.10194] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The involvement of mitochondria and of mitochondrial DNA (mtDNA) in the aging process has generated much interest and even more controversy. The mitochondrial theory of aging considers a vicious circle consisting of: (1) accumulation of somatic mtDNA mutations; (2) impairment of respiratory chain function; (3) increased production of reactive oxygen species (ROS) in mitochondria; and (4) further damage to mtDNA. We review the evidence for and against the belief that these steps occur in aging muscle and brain, considering separately morphological, biochemical, and molecular data. The relationship between mitochondrial aging and late-onset neurodegenerative diseases is briefly reviewed. We conclude that mitochondrial dysfunction does play a crucial role in the aging process of both muscle and brain, but it remains unclear whether mitochondria are the culprits or mere accomplices.
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Affiliation(s)
- Salvatore DiMauro
- Department of Neurology, Columbia University College of Physicians & Surgeons, 630 West 168th Street, New York, New York 10032, USA.
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37
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Diaz F, Bayona-Bafaluy MP, Rana M, Mora M, Hao H, Moraes CT. Human mitochondrial DNA with large deletions repopulates organelles faster than full-length genomes under relaxed copy number control. Nucleic Acids Res 2002; 30:4626-33. [PMID: 12409452 PMCID: PMC135822 DOI: 10.1093/nar/gkf602] [Citation(s) in RCA: 127] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Partially-deleted mitochondrial DNA (DeltamtDNA) accumulates during aging of postmitotic tissues. This accumulation has been linked to decreased metabolic activity, increased reactive oxygen species formation and the aging process. Taking advantage of cell lines with heteroplasmic mtDNA mutations, we showed that, after severe mtDNA depletion, organelles are quickly and predominantly repopulated with DeltamtDNA, whereas repopulation with the wild-type counterpart is slower. This behavior was not observed for full-length genomes with pathogenic point mutations. The faster repopulation of smaller molecules was supported by metabolic labeling of mtDNA with [3H]thymidine during relaxed copy number control conditions. We also showed that hybrid cells containing two defective mtDNA haplotypes tend to retain the smaller one as they adjust their normal mtDNA copy number. Taken together, our results indicate that, under relaxed copy number control, DeltamtDNAs repopulate mitochondria more efficiently than full-length genomes.
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Affiliation(s)
- Francisca Diaz
- Department of Neurology, University of Miami, School of Medicine, Miami, FL 33136, USA
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Wortmann RL, DiMauro S. Differentiating idiopathic inflammatory myopathies from metabolic myopathies. Rheum Dis Clin North Am 2002; 28:759-78. [PMID: 12506771 DOI: 10.1016/s0889-857x(02)00022-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
The metabolic myopathies are a heterogeneous group of diseases, including glycogenoses, disorders of lipid metabolism, and mitochondrial myopathies, that result primarily from inborn errors of metabolism. Most of these metabolic defects cause medical conditions that manifest early in life. Nevertheless, clinical presentations during the teenage years and adulthood are increasingly being recognized. Many of the clinical manifestations of these diseases are difficult to differentiate from those observed in the idiopathic inflammatory myopathies, especially polymyositis. A directed evaluation using the clinical, laboratory, and genetic approaches summarized in this article, however, should allow for the differentiation of most metabolic myopathies from polymyositis and other forms of idiopathic inflammatory myopathy. The diagnosis of a metabolic myopathy should be considered in patients who appear to have polymyositis but lack the characteristic changes of inflammation found on EMG, MRI, or muscle histology, or in such patients who are refractory to immunosuppressive therapy. The forearm ischemic exercise test is especially useful to screen for some inborn errors of glycogen metabolism or glycolysis and for myoadenylate deaminase deficiency. Thorough analysis of muscle tissue, including histology, histochemistry, biochemistry, and occasionally electron microscopy, is often necessary to make the diagnosis of a metabolic myopathy. Advances in molecular biology methods and knowledge of the precise genetic defects associated with these metabolic defects are dramatically increasing our capacity to diagnose patients with a widening range of myopathies. It is expected that, with further understanding of the mechanisms of the metabolic and idiopathic inflammatory myopathies, the differentiation of these disorders into their pathogenetic components, and the capacity to diagnose them will continue to improve. These are essential factors in improving genetic counseling and eventually the therapy of these serious, and currently incurable, disorders.
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Affiliation(s)
- Robert L Wortmann
- Department of Internal Medicine, University of Oklahoma College of Medicine-Tulsa, 4502 East 41st Street, Tulsa, OK 74137, USA.
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Cortopassi GA. A neutral theory predicts multigenic aging and increased concentrations of deleterious mutations on the mitochondrial and Y chromosomes. Free Radic Biol Med 2002; 33:605-10. [PMID: 12208346 DOI: 10.1016/s0891-5849(02)00966-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Population genetic forces have molded the constitution of the human genome over evolutionary time, and some of the most important parameters are the initial frequency of the allele, p, the effective population size, Ne, and the selection coefficient, s. There is considerable agreement among evolutionary gerontologists that the amplitude of -s is small for alleles that are Deleterious In Late Life (DILL), and thus DILL traits are effectively neutral and should be fixed in the human population in relationship to Ne and p. Even higher rates of fixation of deleterious mutations are predicted to occur in the two nonrecombinant genomes in humans, i.e., the Y chromosome and the mitochondrial genome, as a consequence of their lower Ne than autosomes, and the predicted higher rate of fixation of deleterious alleles on the Y may explain the reduced average life span of males vs. females. The high probability of fixation of neutral and mildly deleterious mutations in the mitochondrial genome explains in part its fast rate of evolution, the high observed frequency of mitochondrial disease in relationship to this genome's small size, and may be the underlying reason for the transfer of mitochondrial genes over evolutionary time to the nucleus. The predicted higher concentration of deleterious mutations on the mitochondrial genome could have some leverage to cause more dysfunction than that predicted by mitochondrial gene number alone, because of the essential role of mitochondrial gene function in multisubunit complexes, the coupling of mitochondrial functions, the observation that some mtDNA sequences facilitate somatic mutation, and the likelihood of deleterious mutations either increasing the production of or the sensitivity to mitochondrial ROS.
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Affiliation(s)
- Gino A Cortopassi
- Department of Molecular Biosciences, University of California, Davis, CA 95616, USA.
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Laguno M, Miró O, Perea M, Picón M, Urbano-Márquez A, Grau JM. Muscle diseases in elders: a 10-year retrospective study. J Gerontol A Biol Sci Med Sci 2002; 57:M378-84. [PMID: 12023267 DOI: 10.1093/gerona/57.6.m378] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Muscle complaints are frequent among older adults, but histological data in this setting are scarce. Our objective was to detect the major categories of muscle diseases in the elderly population based on histological study. METHODS We reviewed all muscle biopsies performed in our hospital on patients older than the age of 65 during a 10-year period (1988-1997). As a control group, we included the next patient younger than 65 who underwent muscle biopsy after each elderly patient. We recorded demographic, clinical, and histological data of the patients, as well as the final diagnosis. Concordance between pre- and postbiopsy diagnosis was also analyzed. RESULTS We included 239 muscle biopsies corresponding to elderly patients and 239 to controls. Compared with the control group, elderly patients more frequently exhibited type II fiber atrophy and were diagnosed with a specific myopathy. The latter was achieved in 86 cases (36%), idiopathic inflammatory myopathies and vasculitis being the most frequent diagnoses. Interestingly, in about one quarter of the elderly patients in whom a definite diagnosis of muscle disease was achieved, this diagnosis had not been clinically suspected prior to muscle biopsy. Overall, in 60 out of 239 elderly patients (25%), a specific therapeutic regimen could be instituted on the basis of the muscle biopsy results. CONCLUSIONS Muscle diseases are not rare in elderly patients. Therefore, muscle biopsy constitutes a safe and useful tool for diagnosis because, if not performed, some potentially treatable diseases may be undiagnosed or misdiagnosed.
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Affiliation(s)
- Montserrat Laguno
- Muscle Research Unit, Department of Internal Medicine, August Pi i Sunyer Biomedical Research Institute (IDIBAPS), Hospital Clínic, University of Barcelona, Catalonia, Spain
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Bua EA, McKiernan SH, Wanagat J, McKenzie D, Aiken JM. Mitochondrial abnormalities are more frequent in muscles undergoing sarcopenia. J Appl Physiol (1985) 2002; 92:2617-24. [PMID: 12015381 DOI: 10.1152/japplphysiol.01102.2001] [Citation(s) in RCA: 159] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The hypothesis that the accumulation of electron transport system (ETS) abnormalities and sarcopenia are linked was investigated. Vastus lateralis, soleus, and adductor longus muscles were studied in 5-, 18-, and 36-mo-old male Fischer 344 x Brown Norway F(1) hybrid rats. A significant decrease in soleus and vastus lateralis muscle mass was observed with age. Adductor longus was resistant to muscle mass loss. Multiple serial sections were analyzed for the activities of cytochrome-c oxidase (COX) and succinate dehydrogenase (SDH). The number of fibers exhibiting a COX(-)/SDH(++) phenotype increased with age in both vastus lateralis and soleus muscles. No ETS-abnormal fibers were identified in adductor longus at any age. Cross-sectional area of ETS-abnormal fibers decreased in the abnormal region (region displaying COX(-)/SDH(++) phenotype), whereas control fibers did not. The vastus lateralis muscle, which undergoes a high degree of sarcopenia, exhibited more ETS abnormalities and associated fiber loss than the soleus and adductor longus muscles, which are more resistant to sarcopenia, suggesting a direct association between ETS abnormalities and fiber loss.
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MESH Headings
- Anatomy, Cross-Sectional
- Animals
- Body Weight
- Electron Transport
- Electron Transport Complex IV/metabolism
- Female
- Male
- Mitochondria, Muscle/metabolism
- Muscle Fibers, Fast-Twitch/metabolism
- Muscle Fibers, Fast-Twitch/ultrastructure
- Muscle Fibers, Slow-Twitch/metabolism
- Muscle Fibers, Slow-Twitch/ultrastructure
- Muscle, Skeletal/metabolism
- Muscle, Skeletal/pathology
- Muscular Atrophy/metabolism
- Muscular Atrophy/pathology
- Organ Size
- Rats
- Rats, Inbred BN
- Rats, Inbred F344
- Succinate Dehydrogenase/metabolism
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Affiliation(s)
- Entela A Bua
- Department of Animal Health and Biomedical Sciences, University of Wisconsin, Madison, Wisconsin 53706, USA
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McKenzie D, Bua E, McKiernan S, Cao Z, Aiken JM. Mitochondrial DNA deletion mutations: a causal role in sarcopenia. EUROPEAN JOURNAL OF BIOCHEMISTRY 2002; 269:2010-5. [PMID: 11985577 DOI: 10.1046/j.1432-1033.2002.02867.x] [Citation(s) in RCA: 102] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Mitochondrial DNA (mtDNA) deletion mutations accumulate with age in tissues of a variety of species. Although the relatively low calculated abundance of these deletion mutations in whole tissue homogenates led some investigators to suggest that these mutations do not have any physiological impact, their focal and segmental accumulation suggests that they can, and do, accumulate to levels sufficient to affect the metabolism of a tissue. This phenomenon is most clearly demonstrated in skeletal muscle, where the accumulation of mtDNA deletion mutations remove critical subunits that encode for the electron transport system (ETS). In this review, we detail and provide evidence for a molecular basis of muscle fiber loss with age. Our data suggest that the mtDNA deletion mutations, which are generated in tissues with age, cause muscle fiber loss. Within a fiber, the process begins with a mtDNA replication error, an error that results in a loss of 25-80% of the mitochondrial genome. This smaller genome is replicated and, through a process not well understood, eventually comprises the majority of mtDNA within the small affected region of the muscle fiber. The preponderance of the smaller genomes results in a dysfunctional ETS in the affected area. As a consequence of both the decline in energy production and the increase in oxidative damage in the region, the fiber is no longer capable of self-maintenance, resulting in the observed intrafiber atrophy and fiber breakage. We are therefore proposing that a process contained within a very small region of a muscle fiber can result in breakage and loss of muscle fiber from the tissue.
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Affiliation(s)
- Debbie McKenzie
- Department of Animal Health and Biomedical Sciences, University of Wisconsin, Madison, WI 53706, USA
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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]
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Hirano M, Marti R, Ferreiro-Barros C, Vilà MR, Tadesse S, Nishigaki Y, Nishino I, Vu TH. Defects of intergenomic communication: autosomal disorders that cause multiple deletions and depletion of mitochondrial DNA. Semin Cell Dev Biol 2001; 12:417-27. [PMID: 11735376 DOI: 10.1006/scdb.2001.0279] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Depletion and multiple deletions of mitochondrial DNA (mtDNA) have been associated with a growing number of autosomal diseases that have been classified as defects of intergenomic communication. MNGIE, an autosomal recessive disorder associated with mtDNA alterations is due to mutations in thymidine phosphorylase that may cause imbalance of the mitochondrial nucleotide pool. Subsequently, mutations in the mitochondrial proteins adenine nucleotide translocator 1, Twinkle, and polymerase gamma have been found to cause autosomal dominant progressive external ophthalmoplegia with multiple deletions of mtDNA. Uncovering the molecular bases of intergenomic communication defects will enhance our understanding of the mechanisms responsible for maintaining mtDNA integrity.
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Affiliation(s)
- M Hirano
- Department of Neurology, Columbia University College of Physicians and Surgeons, 630 West 168th Street, New York, NY 10032, USA.
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Chariot P, Chevalier X, Yerroum M, Drogou I, Authier FJ, Gherardi R. Impaired redox status and cytochrome c oxidase deficiency in patients with polymyalgia rheumatica. Ann Rheum Dis 2001; 60:1016-20. [PMID: 11602471 PMCID: PMC1753428 DOI: 10.1136/ard.60.11.1016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
OBJECTIVE To evaluate redox status and muscular mitochondrial abnormalities in patients with polymyalgia rheumatica (PMR). METHODS Prospective evaluation of deltoid muscle biopsy in 15 patients with PMR. Fifteen subjects matched for age and sex, with histologically normal muscle and without clinical evidence of myopathy, were used as controls. Cryostat sections of muscle were processed for conventional dyes, cytochrome c oxidase (COX), usual histochemical reactions, and Sudan black. A total of 300-800 fibres was examined in each case. Blood lactate, pyruvate, and lactate/pyruvate ratio were determined in all patients. RESULTS Ragged red fibres were found in eight patients with PMR and accounted for 0-0.5% of fibres. Focal COX deficiency was found in 14 (93%) of 15 patients and in nine (60%) of 15 controls. COX deficient fibres were more common in patients with PMR (range 0-2.5%; mean 0.9%) than in controls (range 0-1.2%; mean 0.3%) (paired t test, p=0.001). Seven (47%) of 15 patients had high blood lactate levels (1.50-2.60 mmol/l) or high blood lactate/pyruvate ratios (22-25). CONCLUSIONS PMR is associated with mitochondrial abnormalities not solely related to the aging process.
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Affiliation(s)
- P Chariot
- Department of Pathology (Neuromuscular Disorders), Hôpital Henri-Mondor, 94000 Créteil, France.
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Parra D, González A, Mugueta C, Martínez A, Monreal I. Laboratory approach to mitochondrial diseases. J Physiol Biochem 2001; 57:267-84. [PMID: 11800289 DOI: 10.1007/bf03179820] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Dysfunction in mitochondrial processes has been related to several pathologies. In these disorders, the cell suffers oxidative imbalance that is mostly due to defects in pyruvate metabolism, mitochondrial fatty acids oxidation, the citric acid cycle or electron transport by the mitochondrial respiratory chain. These metabolic alterations produce mitochondrial diseases that have been related to inherited syndromes, such as MERRF or MELAS. The main affected organs are brain, skeletal muscle, kidney, heart and liver, because of the high energetic demand and the oxidative metabolism. Moreover, the relationship between mitochondrial dysfunction and neurodegenerative processes, such as Parkinson disease or Alzheimer disease, as well as ageing, has been shown. Because mitochondrias are the target of several xenobiotics, such as aspirin, AZT or alcohol consumption, mitochondrial impairment has also been proposed as a mechanism of toxicity. Most laboratory tests that are available in the diagnosis of mitochondrial illness are assayed in tissue biopsies and are usually difficult to interpret. Recently, it has been shown that non-invasive techniques, such as nuclear magnetic resonance or the 2-keto[1-(13)C]isocaproic acid breath test, may be useful to assess mitochondrial function. This article attempts to show the laboratory approach to mitochondrial diseases, reviewing new techniques that could be of great value in the research of mitochondrial function, such as the 2-keto[1-(13)C]isocaproic breath test.
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Affiliation(s)
- D Parra
- Department of Clinical Biochemistry, Clínica Universitaria de Navarra, Pamplona, Spain
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Rollins S, Prayson RA, McMahon JT, Cohen BH. Diagnostic yield muscle biopsy in patients with clinical evidence of mitochondrial cytopathy. Am J Clin Pathol 2001; 116:326-30. [PMID: 11554158 DOI: 10.1309/watb-w4qv-na53-b9my] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
Abstract
We retrospectively reviewed 118 muscle biopsy specimens from 113 patients with clinical and/or biochemical evidence of mitochondrial cytopathy. Light microscopic evaluation revealed histologic abnormalities in 65 specimens. The most common histologic findings included angular atrophic esterase-positive muscle fibers, type II muscle atrophy, regenerating muscle fibers, and scattered cytochrome-oxidase deficient fibers. Ragged red fibers were noted in 3 specimens on a Gomori trichrome stain. Electron microscopic evaluation was performed in 113 muscle specimens, and in 34, no abnormalities were identified. Increased numbers of mitochondria, particularly in the subsarcolemmal region, were identified in 54 specimens. Increased mitochondrial size was seen in 8 specimens and paracrystalline mitochondrial inclusions in 3. Other ultrastructural findings included focally increased glycogen deposition, focal Z-band streaming, and focally increased lipid accumulation. For 39 cases, concomitant skin biopsy specimens were available; abnormalities were identified by electron microscopy in 12. The majority of biopsy specimens demonstrated some light or electron microscopic abnormality. Specific histologic findings suggestive of mitochondrial abnormalities (partial cytochrome oxidase deficiency, ragged red fibers) were noted in a minority of cases. Ultrastructural evidence of mitochondrial abnormalities was noted in the majority of cases.
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Affiliation(s)
- S Rollins
- Ohio State University College of Medicine and Public Health, Cleveland, USA
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Clay AS, Behnia M, Brown KK. Mitochondrial disease: a pulmonary and critical-care medicine perspective. Chest 2001; 120:634-48. [PMID: 11502670 DOI: 10.1378/chest.120.2.634] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
The clinical spectrum of mitochondrial diseases has expanded dramatically in the last decade. Abnormalities of mitochondrial function are now thought to participate in a number of common adult diseases, ranging from exercise intolerance to aging. This review outlines the common presentations of mitochondrial disease in ICUs and in the outpatient setting and discusses current diagnostic and therapeutic options as they pertain to the pulmonary and critical-care physician.
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Affiliation(s)
- A S Clay
- Department of Internal Medicine, Indiana University School of Medicine, Indianapolis, IN, USA
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Pesce V, Cormio A, Fracasso F, Vecchiet J, Felzani G, Lezza AM, Cantatore P, Gadaleta MN. Age-related mitochondrial genotypic and phenotypic alterations in human skeletal muscle. Free Radic Biol Med 2001; 30:1223-33. [PMID: 11368920 DOI: 10.1016/s0891-5849(01)00517-2] [Citation(s) in RCA: 119] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
To have a clearer picture of how mitochondrial damages are associated to aging, a comprehensive study of phenotypic and genotypic alterations was carried out, analyzing with histochemical and molecular biology techniques the same skeletal muscle specimens of a large number of healthy subjects from 13 to 92 years old. Histochemical data showed that ragged red fibers (RRF) appear at about 40 years of age and are mostly cytochrome c oxidase (COX)-positive, whereas they are almost all COX-negative thereafter. Molecular analyses showed that the 4977 bp deletion of mitochondrial DNA (mtDNA(4977)) and the 7436 bp deletion of mtDNA (mtDNA(7436)) are already present in individuals younger than 40 years of age, but their occurrence does not change with age. After 40 years of age the number of mtDNA deleted species, as revealed by Long Extension PCR (LX-PCR), increases, the 10422 bp deletion of mtDNA (mtDNA(10422)) appears, although with a very low frequency of occurrence, and mtDNA content is more than doubled. Furthermore, mtDNA(4977) level directly correlates with that of COX-negative fibers in the same analyzed subjects. These data clearly show that, after 40 years of age, the phenotypic and genotypic mitochondrial alterations here studied appear in human skeletal muscle and that they are closely related.
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Affiliation(s)
- V Pesce
- Department of Biochemistry and Molecular Biology, University of Bari and Center for the Study of Mitochondria and Energetic Metabolism, Bari, Italy
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Abstract
The first description of a patient with mitochondrial myopathy and deficient respiratory chain function was reported by Luft and coworkers almost 40 years ago. Subsequent studies in the 1970s and 1980s relied on a combination of morphological and biochemical methods to identify patients with mitochondrial disorders. However, the aetiology and pathogenesis remained largely unsolved and there was poor correlation between laboratory findings and clinical phenotypes. The fact that both mitochondrial DNA (mtDNA) and nuclear genes are necessary for the biogenesis of the respiratory chain, suggested that mutations of either genome might cause mitochondrial myopathy. This prediction has been verified during the last decade and pathogenic mutations of both genomes have been identified. This rapid accumulation of genetic information has lead to many good correlations between genotype and phenotype in mitochondrial disorders. The challenge for the future will be to elucidate molecular details of pathogenic processes and to develop effective treatments for patients with respiratory chain dysfunction.
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Affiliation(s)
- N G Larsson
- Department of Molecular Medicine, Karolinska Institutet, Centre for Molecular Medicine, Karolinska Hospital, Stockholm, Sweden
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