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Mukherjee A, Becerra Calixto AD, Chavez M, Delgado JP, Soto C. Mitochondrial transplant to replenish damaged mitochondria: A novel therapeutic strategy for neurodegenerative diseases? PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2020; 177:49-63. [PMID: 33453942 DOI: 10.1016/bs.pmbts.2020.10.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Neurodegenerative diseases are currently some of the most debilitating and incurable illness, including highly prevalent disorders, such as Alzheimer's and Parkinson's disease. Despite impressive advances in understanding the molecular basis of neurodegenerative diseases, several clinical trials have failed in identifying drugs that successfully delay or stop disease progression. New targets are likely necessary to successfully combat these devastating diseases. In this chapter, we review the evidence indicating that impairment in the cellular energy machinery in the form of mitochondrial damage and dysfunction may be at the root of neurodegeneration. We also propose that transplant of functional isolated mitochondria may overcome the energetic damage and delay the progression of neurodegenerative diseases.
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Affiliation(s)
- Abhisek Mukherjee
- Mitchell Center Alzheimer's Disease and Related Brain Disorders, Department of Neurology, McGovern Medical School, University of Texas Houston Medical School, Houston, TX, United States
| | - Andrea D Becerra Calixto
- Mitchell Center Alzheimer's Disease and Related Brain Disorders, Department of Neurology, McGovern Medical School, University of Texas Houston Medical School, Houston, TX, United States
| | - Melissa Chavez
- Mitchell Center Alzheimer's Disease and Related Brain Disorders, Department of Neurology, McGovern Medical School, University of Texas Houston Medical School, Houston, TX, United States
| | - Jean Paul Delgado
- Grupo Genética, Regeneración & Cáncer, Instituto de Biología, Universidad de Antioquia, Medellín, Colombia
| | - Claudio Soto
- Mitchell Center Alzheimer's Disease and Related Brain Disorders, Department of Neurology, McGovern Medical School, University of Texas Houston Medical School, Houston, TX, United States.
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2
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Hood WR, Williams AS, Hill GE. An Ecologist’s Guide to Mitochondrial DNA Mutations and Senescence. Integr Comp Biol 2019; 59:970-982. [DOI: 10.1093/icb/icz097] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Abstract
Longevity plays a key role in the fitness of organisms, so understanding the processes that underlie variance in senescence has long been a focus of ecologists and evolutionary biologists. For decades, the performance and ultimate decline of mitochondria have been implicated in the demise of somatic tissue, but exactly why mitochondrial function declines as individual’s age has remained elusive. A possible source of decline that has been of intense debate is mutations to the mitochondrial DNA. There are two primary sources of such mutations: oxidative damage, which is widely discussed by ecologists interested in aging, and mitochondrial replication error, which is less familiar to most ecologists. The goal of this review is to introduce ecologists and evolutionary biologists to the concept of mitochondrial replication error and to review the current status of research on the relative importance of replication error in senescence. We conclude by detailing some of the gaps in our knowledge that currently make it difficult to deduce the relative importance of replication error in wild populations and encourage organismal biologists to consider this variable both when interpreting their results and as viable measure to include in their studies.
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Affiliation(s)
- Wendy R Hood
- Department of Biological Sciences, Auburn University, Auburn, AL 36849, USA
| | - Ashley S Williams
- Department of Biological Sciences, Auburn University, Auburn, AL 36849, USA
| | - Geoffrey E Hill
- Department of Biological Sciences, Auburn University, Auburn, AL 36849, USA
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Kapnick SM, Pacheco SE, McGuire PJ. The emerging role of immune dysfunction in mitochondrial diseases as a paradigm for understanding immunometabolism. Metabolism 2018; 81:97-112. [PMID: 29162500 PMCID: PMC5866745 DOI: 10.1016/j.metabol.2017.11.010] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Revised: 11/07/2017] [Accepted: 11/11/2017] [Indexed: 01/08/2023]
Abstract
Immunometabolism aims to define the role of intermediary metabolism in immune cell function, with bioenergetics and the mitochondria recently taking center stage. To date, the medical literature on mitochondria and immune function extols the virtues of mouse models in exploring this biologic intersection. While the laboratory mouse has become a standard for studying mammalian biology, this model comprises part of a comprehensive approach. Humans, with their broad array of inherited phenotypes, serve as a starting point for studying immunometabolism; specifically, patients with mitochondrial disease. Using this top-down approach, the mouse as a model organism facilitates further exploration of the consequences of mutations involved in mitochondrial maintenance and function. In this review, we will discuss the emerging phenotype of immune dysfunction in mitochondrial disease as a model for understanding the role of the mitochondria in immune function in available mouse models.
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Affiliation(s)
- Senta M Kapnick
- Metabolism, Infection and Immunity Section, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA
| | - Susan E Pacheco
- Department of Pediatrics, The University of Texas Health Science Center, Houston, TX, USA
| | - Peter J McGuire
- Metabolism, Infection and Immunity Section, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA.
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4
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The Mitochondrial Basis of Aging and Age-Related Disorders. Genes (Basel) 2017; 8:genes8120398. [PMID: 29257072 PMCID: PMC5748716 DOI: 10.3390/genes8120398] [Citation(s) in RCA: 185] [Impact Index Per Article: 26.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Revised: 12/09/2017] [Accepted: 12/13/2017] [Indexed: 12/21/2022] Open
Abstract
Aging is a natural phenomenon characterized by progressive decline in tissue and organ function leading to increased risk of disease and mortality. Among diverse factors that contribute to human aging, the mitochondrial dysfunction has emerged as one of the key hallmarks of aging process and is linked to the development of numerous age-related pathologies including metabolic syndrome, neurodegenerative disorders, cardiovascular diseases and cancer. Mitochondria are central in the regulation of energy and metabolic homeostasis, and harbor a complex quality control system that limits mitochondrial damage to ensure mitochondrial integrity and function. The intricate regulatory network that balances the generation of new and removal of damaged mitochondria forms the basis of aging and longevity. Here, I will review our current understanding on how mitochondrial functional decline contributes to aging, including the role of somatic mitochondrial DNA (mtDNA) mutations, reactive oxygen species (ROS), mitochondrial dynamics and quality control pathways. I will further discuss the emerging evidence on how dysregulated mitochondrial dynamics, mitochondrial biogenesis and turnover mechanisms contribute to the pathogenesis of age-related disorders. Strategies aimed to enhance mitochondrial function by targeting mitochondrial dynamics, quality control, and mitohormesis pathways might promote healthy aging, protect against age-related diseases, and mediate longevity.
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Neuhaus JFG, Baris OR, Kittelmann A, Becker K, Rothschild MA, Wiesner RJ. Catecholamine Metabolism Induces Mitochondrial DNA Deletions and Leads to Severe Adrenal Degeneration during Aging. Neuroendocrinology 2017; 104:72-84. [PMID: 26895241 DOI: 10.1159/000444680] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Accepted: 02/12/2016] [Indexed: 11/19/2022]
Abstract
BACKGROUND Aging is a multifactorial process characterized by organ loss of function and degeneration, but the mechanisms involved remain elusive. We have shown recently that catecholamine metabolism drives the accumulation of mitochondrial DNA (mtDNA) deletions in dopaminergic cells, which likely contribute to their degeneration during aging. Here we investigated whether the well-documented degeneration and altered function of adrenals during aging is linked to catecholamine production in the medulla followed by accumulation of mtDNA deletions. MATERIAL AND METHODS We analyzed adrenal medullary and cortical samples of both murine and human origin covering a wide range of ages for mtDNA deletion content, mtDNA copy number, mitochondrial and cellular integrity as well as aging-related tissue changes such as fibrosis. RESULTS Indeed, we demonstrate in mice and humans that the adrenal medulla accumulates a strikingly high amount of mtDNA deletions with age, causing mitochondrial dysfunction in the adrenal medulla, but also in the cortex, accompanied by apoptosis and, more importantly, by severe inflammation and remarkable fibrosis. Additionally, a concomitant and dramatic loss of medullary and cortical cells is observed in old animals. CONCLUSION Our results show that accumulation of mtDNA deletions, and the ensuing mitochondrial dysfunction, is a hallmark of adrenal aging, further strengthening the hypothesis that catecholamine metabolism is detrimental to mtDNA integrity, mitochondrial function and cell survival. Moreover, the cell loss potentially induced by mitochondrial dysfunction could explain the decline in adrenal hormonal and steroidal secretion during aging.
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Affiliation(s)
- Johannes Friedrich Georg Neuhaus
- Center for Physiology and Pathophysiology, Institute of Vegetative Physiology, Medical Faculty, University of Cologne, Cologne, Germany
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6
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Lax NZ, Gorman GS, Turnbull DM. Review: Central nervous system involvement in mitochondrial disease. Neuropathol Appl Neurobiol 2016; 43:102-118. [PMID: 27287935 PMCID: PMC5363248 DOI: 10.1111/nan.12333] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Revised: 06/03/2016] [Accepted: 06/11/2016] [Indexed: 12/13/2022]
Abstract
Mitochondrial respiratory chain defects are an important cause of inherited disorders affecting approximately 1 in 5000 people in the UK population. Collectively these disorders are termed ‘mitochondrial diseases’ and they result from either mitochondrial DNA mutations or defects in nuclear DNA. Although they are frequently multisystem disorders, neurological deficits are particularly common, wide‐ranging and disabling for patients. This review details the manifold neurological impairments associated with mitochondrial disease, and describes the efforts to understand how they arise and progressively worsen in patients with mitochondrial disease. We describe advances in our understanding of disease pathogenesis through detailed neuropathological studies and how this has spurred the development of cellular and animal models of disease. We underscore the importance of continued clinical, molecular genetic, neuropathological and animal model studies to fully characterize mitochondrial diseases and understand mechanisms of neurodegeneration. These studies are instrumental for the next phase of mitochondrial research that has a particular emphasis on finding novel ways to treat mitochondrial disease to improve patient care and quality of life.
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Affiliation(s)
- N Z Lax
- The Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
| | - G S Gorman
- The Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
| | - D M Turnbull
- The Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
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Martin SA, DeMuth TM, Miller KN, Pugh TD, Polewski MA, Colman RJ, Eliceiri KW, Beasley TM, Johnson SC, Anderson RM. Regional metabolic heterogeneity of the hippocampus is nonuniformly impacted by age and caloric restriction. Aging Cell 2016; 15:100-10. [PMID: 26521867 PMCID: PMC4717265 DOI: 10.1111/acel.12418] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/17/2015] [Indexed: 12/03/2022] Open
Abstract
The hippocampus is critical for cognition and memory formation and is vulnerable to age‐related atrophy and loss of function. These phenotypes are attenuated by caloric restriction (CR), a dietary intervention that delays aging. Here, we show significant regional effects in hippocampal energy metabolism that are responsive to age and CR, implicating metabolic pathways in neuronal protection. In situ mitochondrial cytochrome c oxidase activity was region specific and lower in aged mice, and the impact of age was region specific. Multiphoton laser scanning microscopy revealed region‐ and age‐specific differences in nicotinamide adenine dinucleotide (NAD)‐derived metabolic cofactors. Age‐related changes in metabolic parameters were temporally separated, with early and late events in the metabolic response to age. There was a significant regional impact of age to lower levels of PGC‐1α, a master mitochondrial regulator. Rather than reversing the impact of age, CR induced a distinct metabolic state with decreased cytochrome c oxidase activity and increased levels of NAD(P)H. Levels of hippocampal PGC‐1α were lower with CR, as were levels of GSK3β, a key regulator of PGC‐1α turnover and activity. Regional distribution and colocalization of PGC‐1α and GSK3β in mouse hippocampus was similar in monkeys. Furthermore, the impact of CR to lower levels of both PGC‐1α and GSK3β was also conserved. The studies presented here establish the hippocampus as a highly varied metabolic environment, reveal cell‐type and regional specificity in the metabolic response to age and delayed aging by CR, and suggest that PGC‐1α and GSK3β play a role in implementing the neuroprotective program induced by CR.
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Affiliation(s)
- Stephen A. Martin
- Division of Geriatrics Department of Medicine SMPH University of Wisconsin Madison WI 53705 USA
| | - Tyler M. DeMuth
- Division of Geriatrics Department of Medicine SMPH University of Wisconsin Madison WI 53705 USA
| | - Karl N. Miller
- Division of Geriatrics Department of Medicine SMPH University of Wisconsin Madison WI 53705 USA
| | - Thomas D. Pugh
- Division of Geriatrics Department of Medicine SMPH University of Wisconsin Madison WI 53705 USA
| | - Michael A. Polewski
- Division of Geriatrics Department of Medicine SMPH University of Wisconsin Madison WI 53705 USA
| | - Ricki J. Colman
- Wisconsin National Primate Research Center University of Wisconsin Madison WI 53715 USA
| | - Kevin W. Eliceiri
- Laboratory for Optical and Computational Instrumentation University of Wisconsin Madison WI 53706 USA
| | - Timothy Mark Beasley
- Department of Biostatistics University of Alabama Birmingham AL 35294 USA
- GRECC Birmingham/Atlanta Veterans Administration Hospital Birmingham AL 35294 USA
| | - Sterling C. Johnson
- Division of Geriatrics Department of Medicine SMPH University of Wisconsin Madison WI 53705 USA
- GRECC William S. Middleton Memorial Veterans Hospital Madison WI 53705 USA
| | - Rozalyn M. Anderson
- Division of Geriatrics Department of Medicine SMPH University of Wisconsin Madison WI 53705 USA
- GRECC William S. Middleton Memorial Veterans Hospital Madison WI 53705 USA
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8
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Iommarini L, Peralta S, Torraco A, Diaz F. Mitochondrial Diseases Part II: Mouse models of OXPHOS deficiencies caused by defects in regulatory factors and other components required for mitochondrial function. Mitochondrion 2015; 22:96-118. [PMID: 25640959 DOI: 10.1016/j.mito.2015.01.008] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Accepted: 01/22/2015] [Indexed: 01/21/2023]
Abstract
Mitochondrial disorders are defined as defects that affect the oxidative phosphorylation system (OXPHOS). They are characterized by a heterogeneous array of clinical presentations due in part to a wide variety of factors required for proper function of the components of the OXPHOS system. There is no cure for these disorders owing to our poor knowledge of the pathogenic mechanisms of disease. To understand the mechanisms of human disease numerous mouse models have been developed in recent years. Here we summarize the features of several mouse models of mitochondrial diseases directly related to those factors affecting mtDNA maintenance, replication, transcription, translation as well as other proteins that are involved in mitochondrial dynamics and quality control which affect mitochondrial OXPHOS function without being intrinsic components of the system. We discuss how these models have contributed to our understanding of mitochondrial diseases and their pathogenic mechanisms.
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Affiliation(s)
- Luisa Iommarini
- Department of Pharmacy and Biotechnology (FABIT), University of Bologna, Via Irnerio 42, 40128 Bologna, Italy.
| | - Susana Peralta
- Department of Neurology, University of Miami, Miller School of Medicine, Miami, FL 33136, USA.
| | - Alessandra Torraco
- Unit for Neuromuscular and Neurodegenerative Disorders, Laboratory of Molecular Medicine, Bambino Gesù Children's Hospital, IRCCS, Viale di San Paolo, 15 - 00146, Rome, Italy.
| | - Francisca Diaz
- Department of Neurology, University of Miami, Miller School of Medicine, Miami, FL 33136, USA.
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Kozieł R, Ruckenstuhl C, Albertini E, Neuhaus M, Netzberger C, Bust M, Madeo F, Wiesner RJ, Jansen‐Dürr P. Methionine restriction slows down senescence in human diploid fibroblasts. Aging Cell 2014; 13:1038-48. [PMID: 25273919 PMCID: PMC4326930 DOI: 10.1111/acel.12266] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/08/2014] [Indexed: 12/31/2022] Open
Abstract
Methionine restriction (MetR) extends lifespan in animal models including rodents. Using human diploid fibroblasts (HDF), we report here that MetR significantly extends their replicative lifespan, thereby postponing cellular senescence. MetR significantly decreased activity of mitochondrial complex IV and diminished the accumulation of reactive oxygen species. Lifespan extension was accompanied by a significant decrease in the levels of subunits of mitochondrial complex IV, but also complex I, which was due to a decreased translation rate of several mtDNA-encoded subunits. Together, these findings indicate that MetR slows down aging in human cells by modulating mitochondrial protein synthesis and respiratory chain assembly.
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Affiliation(s)
- Rafał Kozieł
- Institute for Biomedical Aging Research (IBA) Universität Innsbruck Rennweg 10 6020Innsbruck Austria
| | - Christoph Ruckenstuhl
- Institute of Molecular Biosciences Karl‐Franzens University Humboldtstrasse 50 8010Graz Austria
| | - Eva Albertini
- Institute for Biomedical Aging Research (IBA) Universität Innsbruck Rennweg 10 6020Innsbruck Austria
| | - Michael Neuhaus
- Institute for Biomedical Aging Research (IBA) Universität Innsbruck Rennweg 10 6020Innsbruck Austria
| | - Christine Netzberger
- Institute of Molecular Biosciences Karl‐Franzens University Humboldtstrasse 50 8010Graz Austria
| | - Maria Bust
- Institute for Vegetative Physiology University of Köln Robert‐Kochstr. 39 50931Köln Germany
| | - Frank Madeo
- Institute of Molecular Biosciences Karl‐Franzens University Humboldtstrasse 50 8010Graz Austria
| | - Rudolf J. Wiesner
- Institute for Vegetative Physiology University of Köln Robert‐Kochstr. 39 50931Köln Germany
- Center for Molecular Medicine Cologne University of Köln Robert‐Kochstr. 21 50931Köln Germany
- Cologne Excellence Cluster on Cellular Stress Responses in Aging‐associated Diseases (CECAD) Joseph‐Stelzmannstr. 26 50931Köln Germany
| | - Pidder Jansen‐Dürr
- Institute for Biomedical Aging Research (IBA) Universität Innsbruck Rennweg 10 6020Innsbruck Austria
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10
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Kemppainen KK, Rinne J, Sriram A, Lakanmaa M, Zeb A, Tuomela T, Popplestone A, Singh S, Sanz A, Rustin P, Jacobs HT. Expression of alternative oxidase in Drosophila ameliorates diverse phenotypes due to cytochrome oxidase deficiency. Hum Mol Genet 2013; 23:2078-93. [PMID: 24293544 PMCID: PMC3959817 DOI: 10.1093/hmg/ddt601] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Mitochondrial dysfunction is a significant factor in human disease, ranging from systemic disorders of childhood to cardiomyopathy, ischaemia and neurodegeneration. Cytochrome oxidase, the terminal enzyme of the mitochondrial respiratory chain, is a frequent target. Lower eukaryotes possess alternative respiratory-chain enzymes that provide non-proton-translocating bypasses for respiratory complexes I (single-subunit reduced nicotinamide adenine dinucleotide dehydrogenases, e.g. Ndi1 from yeast) or III + IV [alternative oxidase (AOX)], under conditions of respiratory stress or overload. In previous studies, it was shown that transfer of yeast Ndi1 or Ciona intestinalis AOX to Drosophila was able to overcome the lethality produced by toxins or partial knockdown of complex I or IV. Here, we show that AOX can provide a complete or substantial rescue of a range of phenotypes induced by global or tissue-specific knockdown of different cIV subunits, including integral subunits required for catalysis, as well as peripheral subunits required for multimerization and assembly. AOX was also able to overcome the pupal lethality produced by muscle-specific knockdown of subunit CoVb, although the rescued flies were short lived and had a motility defect. cIV knockdown in neurons was not lethal during development but produced a rapidly progressing locomotor and seizure-sensitivity phenotype, which was substantially alleviated by AOX. Expression of Ndi1 exacerbated the neuronal phenotype produced by cIV knockdown. Ndi1 expressed in place of essential cI subunits produced a distinct residual phenotype of delayed development, bang sensitivity and male sterility. These findings confirm the potential utility of alternative respiratory chain enzymes as tools to combat mitochondrial disease, while indicating important limitations thereof.
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Affiliation(s)
- Kia K Kemppainen
- Institute of Biomedical Technology and Tampere University Hospital, University of Tampere, FI-33014 Tampere, Finland
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Abstract
Considerable efforts have been made to understand the role of oxidative stress in age-related diseases and ageing. The mitochondrial free radical theory of ageing, which proposes that damage to mitochondrial DNA (mtDNA) and other macromolecules caused by the production of reactive oxygen species (ROS) during cellular respiration drives ageing, has for a long time been the central hypothesis in the field. However, in contrast with this theory, evidence from an increasing number of experimental studies has suggested that mtDNA mutations may be generated by replication errors rather than by accumulated oxidative damage. Furthermore, interventions to modulate ROS levels in humans and animal models have not produced consistent results in terms of delaying disease progression and extending lifespan. A number of recent experimental findings strongly question the mitochondrial free radical theory of ageing, leading to the emergence of new theories of how age-associated mitochondrial dysfunction may lead to ageing. These new hypotheses are mainly based on the underlying notion that, despite their deleterious role, ROS are essential signalling molecules that mediate stress responses in general and the stress response to age-dependent damage in particular. This novel view of ROS roles has a clear impact on the interpretation of studies in which antioxidants have been used to treat human age-related diseases commonly linked to oxidative stress.
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Affiliation(s)
- M Lagouge
- Department of Mitochondrial Biology, Max Planck Institute for Biology of Ageing, Cologne, Germany
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12
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Abstract
Mitochondrial oxidative phosphorylation (OXPHOS) sustains organelle function and plays a central role in cellular energy metabolism. The OXPHOS system consists of 5 multisubunit complexes (CI-CV) that are built up of 92 different structural proteins encoded by the nuclear (nDNA) and mitochondrial DNA (mtDNA). Biogenesis of a functional OXPHOS system further requires the assistance of nDNA-encoded OXPHOS assembly factors, of which 35 are currently identified. In humans, mutations in both structural and assembly genes and in genes involved in mtDNA maintenance, replication, transcription, and translation induce 'primary' OXPHOS disorders that are associated with neurodegenerative diseases including Leigh syndrome (LS), which is probably the most classical OXPHOS disease during early childhood. Here, we present the current insights regarding function, biogenesis, regulation, and supramolecular architecture of the OXPHOS system, as well as its genetic origin. Next, we provide an inventory of OXPHOS structural and assembly genes which, when mutated, induce human neurodegenerative disorders. Finally, we discuss the consequences of mutations in OXPHOS structural and assembly genes at the single cell level and how this information has advanced our understanding of the role of OXPHOS dysfunction in neurodegeneration.
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13
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Lax NZ, Turnbull DM, Reeve AK. Mitochondrial mutations: newly discovered players in neuronal degeneration. Neuroscientist 2012; 17:645-58. [PMID: 22130639 PMCID: PMC3757997 DOI: 10.1177/1073858411385469] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Mutations in mitochondrial DNA cause a number of neurological diseases with defined neuropathology; however, mutations in this genome have also been found to be important in a number of more common neurodegenerative diseases. In this review, the authors discuss the importance of mitochondrial DNA mutations in a number of different diseases and speculate how such mutations could lead to cell loss. Increasing our understanding of how mitochondrial DNA mutations affect mitochondrial metabolism and subsequently result in neurodegenerative disease will prove vital to the development of targeted therapies and treatments.
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Affiliation(s)
- Nichola Z Lax
- Centre for Brain Ageing and Vitality, Institute for Ageing and Health, Newcastle University, Newcastle upon Tyne, United Kingdom
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14
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Baris OR, Klose A, Kloepper JE, Weiland D, Neuhaus JFG, Schauen M, Wille A, Müller A, Merkwirth C, Langer T, Larsson NG, Krieg T, Tobin DJ, Paus R, Wiesner RJ. The mitochondrial electron transport chain is dispensable for proliferation and differentiation of epidermal progenitor cells. Stem Cells 2012; 29:1459-68. [PMID: 21780252 DOI: 10.1002/stem.695] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Tissue stem cells and germ line or embryonic stem cells were shown to have reduced oxidative metabolism, which was proposed to be an adaptive mechanism to reduce damage accumulation caused by reactive oxygen species. However, an alternate explanation is that stem cells are less dependent on specialized cytoplasmic functions compared with differentiated cells, therefore, having a high nuclear-to-cytoplasmic volume ratio and consequently a low mitochondrial content. To determine whether stem cells rely or not on mitochondrial respiration, we selectively ablated the electron transport chain in the basal layer of the epidermis, which includes the epidermal progenitor/stem cells (EPSCs). This was achieved using a loxP-flanked mitochondrial transcription factor A (Tfam) allele in conjunction with a keratin 14 Cre transgene. The epidermis of these animals (Tfam(EKO)) showed a profound depletion of mitochondrial DNA and complete absence of respiratory chain complexes. However, despite a short lifespan due to malnutrition, epidermal development and skin barrier function were not impaired. Differentiation of epidermal layers was normal and no proliferation defect or major increase of apoptosis could be observed. In contrast, mice with an epidermal ablation of prohibitin-2, a scaffold protein in the inner mitochondrial membrane, displayed a dramatic phenotype observable already in utero, with severely impaired skin architecture and barrier function, ultimately causing death from dehydration shortly after birth. In conclusion, we here provide unequivocal evidence that EPSCs, and probably tissue stem cells in general, are independent of the mitochondrial respiratory chain, but still require a functional dynamic mitochondrial compartment.
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Affiliation(s)
- Olivier R Baris
- Center for Physiology and Pathophysiology, Institute for Vegetative Physiology,University of Cologne, Cologne, Germany
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15
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Mitochondrial transcription: lessons from mouse models. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2011; 1819:961-9. [PMID: 22120174 DOI: 10.1016/j.bbagrm.2011.11.001] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2011] [Revised: 11/09/2011] [Accepted: 11/10/2011] [Indexed: 11/22/2022]
Abstract
Mammalian mitochondrial DNA (mtDNA) is a circular double-stranded DNA genome of ~16.5 kilobase pairs (kb) that encodes 13 catalytic proteins of the ATP-producing oxidative phosphorylation system (OXPHOS), and the rRNAs and tRNAs required for the translation of the mtDNA transcripts. All the components needed for transcription and replication of the mtDNA are, therefore, encoded in the nuclear genome, as are the remaining components of the OXPHOS system and the mitochondrial translation machinery. Regulation of mtDNA gene expression is very important for modulating the OXPHOS capacity in response to metabolic requirements and in pathological processes. The combination of in vitro and in vivo studies has allowed the identification of the core machinery required for basal mtDNA transcription in mammals and a few proteins that regulate mtDNA transcription. Specifically, the generation of knockout mouse strains in the last several years, has been key to understanding the basis of mtDNA transcription in vivo. However, it is well accepted that many components of the transcription machinery are still unknown and little is known about mtDNA gene expression regulation under different metabolic requirements or disease processes. In this review we will focus on how the creation of knockout mouse models and the study of their phenotypes have contributed to the understanding of mitochondrial transcription in mammals. This article is part of a Special Issue entitled: Mitochondrial Gene Expression.
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The striatum is highly susceptible to mitochondrial oxidative phosphorylation dysfunctions. J Neurosci 2011; 31:9895-904. [PMID: 21734281 DOI: 10.1523/jneurosci.6223-10.2011] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Neuronal oxidative phosphorylation (OXPHOS) deficiency has been associated with a variety of neurodegenerative diseases, including Parkinson's disease and Huntington's disease. However, it is not clear how mitochondrial dysfunction alone can lead to a preferential elimination of certain neuronal populations in vivo. We compared different types of neuronal populations undergoing the same OXPHOS deficiency to determine their relative susceptibility and mechanisms responsible for selective neuron vulnerability. We used a mouse model expressing a mitochondria-targeted restriction enzyme, PstI or mito-PstI. The expression of mito-PstI induces double-strand breaks in the mitochondrial DNA (mtDNA), leading to OXPHOS deficiency, mostly due to mtDNA depletion. We targeted mito-PstI expression to the cortex, hippocampus, and striatum under the CaMKII-α promoter. Animals undergoing long-term expression of mito-PstI displayed a selective worsening of the striatum over cortical and hippocampal areas. Mito-PstI expression and mtDNA depletion were not worse in the striatum, but the latter showed the most severe defects in mitochondrial membrane potential, response to calcium, and survival. These results showed that the striatum is particularly sensitive to defects in OXPHOS possibly due to an increased reliance on OXPHOS function in this area and differences in response to physiological stimuli. These results may help explain the neuropathological features associated with Huntington's disease, which have been associated with OXPHOS defects.
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Abstract
The small mammalian mitochondrial DNA (mtDNA) is very gene dense and encodes factors critical for oxidative phosphorylation. Mutations of mtDNA cause a variety of human mitochondrial diseases and are also heavily implicated in age-associated disease and aging. There has been considerable progress in our understanding of the role for mtDNA mutations in human pathology during the last two decades, but important mechanisms in mitochondrial genetics remain to be explained at the molecular level. In addition, mounting evidence suggests that most mtDNA mutations may be generated by replication errors and not by accumulated damage.
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Affiliation(s)
- Chan Bae Park
- Institute for Medical Sciences, Ajou University School of Medicine, Suwon 443-721, Korea
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18
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Abstract
Mutations in mitochondrial DNA cause a number of neurological diseases with defined neuropathology; however, mutations in this genome have also been found to be important in a number of more common neurodegenerative diseases. In this review, the authors discuss the importance of mitochondrial DNA mutations in a number of different diseases and speculate how such mutations could lead to cell loss. Increasing our understanding of how mitochondrial DNA mutations affect mitochondrial metabolism and subsequently result in neurodegenerative disease will prove vital to the development of targeted therapies and treatments.
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Affiliation(s)
- Nichola Z. Lax
- Centre for Brain Ageing and Vitality, Institute for Ageing and Health, Newcastle University, Newcastle upon Tyne, United Kingdom
- Mitochondrial Research Group, Institute for Ageing and Health, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Doug M. Turnbull
- Centre for Brain Ageing and Vitality, Institute for Ageing and Health, Newcastle University, Newcastle upon Tyne, United Kingdom
- Mitochondrial Research Group, Institute for Ageing and Health, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Amy K. Reeve
- Centre for Brain Ageing and Vitality, Institute for Ageing and Health, Newcastle University, Newcastle upon Tyne, United Kingdom
- Mitochondrial Research Group, Institute for Ageing and Health, Newcastle University, Newcastle upon Tyne, United Kingdom
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19
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Czarnecka AM, Bartnik E. The role of the mitochondrial genome in ageing and carcinogenesis. J Aging Res 2011; 2011:136435. [PMID: 21403887 PMCID: PMC3042732 DOI: 10.4061/2011/136435] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2010] [Accepted: 01/03/2011] [Indexed: 01/01/2023] Open
Abstract
Mitochondrial DNA mutations and polymorphisms have been the focus of intensive investigations for well over a decade in an attempt to understand how they affect fundamental processes such as cancer and aging. Initial interest in mutations occurring in mitochondrial DNA of cancer cells diminished when most were found to be the same mutations which occurred during the evolution of human mitochondrial haplogroups. However, increasingly correlations are being found between various mitochondrial haplogroups and susceptibility to cancer or diseases in some cases and successful aging in others.
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Affiliation(s)
- Anna M. Czarnecka
- Laboratory of Molecular Oncology, Department of Oncology, Military Institute of Medicine, ul. Szaserów 128, 01-141 Warsaw, Poland
| | - Ewa Bartnik
- Institute of Genetics and Biotechnology, Faculty of Biology, University of Warsaw, Pawinskiego 5a, 02-106, Warsaw, Poland
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawinskiego 5a, 02-106 Warsaw, Poland
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20
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Choy MS, Chen MJ, Manikandan J, Peng ZF, Jenner AM, Melendez AJ, Cheung NS. Up-regulation of endoplasmic reticulum stress-related genes during the early phase of treatment of cultured cortical neurons by the proteasomal inhibitor lactacystin. J Cell Physiol 2011; 226:494-510. [PMID: 20683911 DOI: 10.1002/jcp.22359] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Inhibition of proteasome degradation pathway has been implicated in neuronal cell death leading to neurodegenerative diseases such as Parkinson's disease and Alzheimer's disease. We and others demonstrated that treatment of cortical neurons with the proteasomal inhibitor lactacystin leads to apoptosis. We discovered by microarray analysis that lactacystin treatment modulates the expression of both potentially neuroprotective as well as pro-apoptotic genes in neurons. However, the significance of the genes which upon transcriptional modulation contributed to proteasomal inhibition-induced apoptosis, remained unidentified. By employing microarray analysis to decipher the time-dependent changes in transcription of these genes in cultured cortical neurons, we discovered different groups of genes were transcriptionally regulated in the early and late phase of lactacystin-induced cell death. In the early phase, several neuroprotective genes such as those encoding the proteasome subunits and ubiquitin-associated enzymes, as well as the heat-shock proteins (HSP) were up-regulated. However, the pro-apoptotic endoplasmic reticulum (ER) stress-associated genes were also up-regulated at the early phase of lactacystin-induced neuronal cell death. In the late phase, genes encoding antioxidants and calcium-binding proteins were up-regulated while those associated with cholesterol biosynthesis were down-regulated. The data suggest that ER stress may participate in mediating the apoptotic responses induced by proteasomal inhibition. The up-regulation of the neuroprotective antioxidant genes and calcium-binding protein genes and down-regulation of the cholesterol biosynthesis genes in the later phase are likely consequences of stimulation of the pro-apoptotic signaling pathways in the early phase of lactacystin treatment.
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Affiliation(s)
- Meng Shyan Choy
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
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21
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Abstract
The essential need for mitochondrial function has been extensively shown to relate to neuronal health. Neurodegeneration and neurodegeneration-related diseases have been associated with multiple mitochondrial dysfunctions. This review highlights key findings related to commonly studied mitochondrial dysfunctions: imbalance of mitochondrial dynamics, mutations in the mitochondrial genome, excessive reactive oxygen species, and misfolded protein associations/interactions with the mitochondria. Future research in mitochondrial function will help elucidate complex neurodegenerative events while impacting both individual and societal health.
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22
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Somatic gene mutation and human disease other than cancer: An update. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2010; 705:96-106. [DOI: 10.1016/j.mrrev.2010.04.002] [Citation(s) in RCA: 147] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2009] [Revised: 03/29/2010] [Accepted: 04/08/2010] [Indexed: 12/24/2022]
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23
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Abstract
Mitochondrial dysfunction is heavily implicated in the multifactorial aging process. Aging humans have increased levels of somatic mtDNA mutations that tend to undergo clonal expansion to cause mosaic respiratory chain deficiency in various tissues, such as heart, brain, skeletal muscle, and gut. Genetic mouse models have shown that somatic mtDNA mutations and cell type-specific respiratory chain dysfunction can cause a variety of phenotypes associated with aging and age-related disease. There is thus strong observational and experimental evidence to implicate somatic mtDNA mutations and mosaic respiratory chain dysfunction in the mammalian aging process. The hypothesis that somatic mtDNA mutations are generated by oxidative damage has not been conclusively proven. Emerging data instead suggest that the inherent error rate of mitochondrial DNA (mtDNA) polymerase gamma (Pol gamma) may be responsible for the majority of somatic mtDNA mutations. The roles for mtDNA damage and replication errors in aging need to be further experimentally addressed.
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24
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Ekstrand MI, Galter D. The MitoPark Mouse - an animal model of Parkinson's disease with impaired respiratory chain function in dopamine neurons. Parkinsonism Relat Disord 2010; 15 Suppl 3:S185-8. [PMID: 20082987 DOI: 10.1016/s1353-8020(09)70811-9] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Parkinson's disease (PD) is a progressive neurodegenerative disorder characterized by selective and progressive degeneration of dopamine neurons in the substantia nigra. While most cases are sporadic a few rare familial forms of PD have been described. Several lines of evidence indicate that mitochondrial dysfunction may be involved in the etiology of the disease. Genes found to cause familial Parkinsonism have been linked to mitochondrial function and toxins that inhibit the mitochondrial respiratory chain have been found to cause dopamine cell death. Furthermore, higher numbers of respiratory chain deficient dopamine neurons are found in patients with PD than in age-matched controls. The MitoPark mouse model of PD was designed to directly test the hypothesis that mitochondrial dysfunction in dopamine neurons can cause a progressive parkinsonian phenotype. By cell type-specific inactivation of mitochondrial transcription factor A, a protein essential for mitochondrial DNA expression and maintenance, dopamine neurons were rendered respiratory chain deficient. MitoPark mice recapitulate several features of PD in humans such as adult-onset degeneration of nigrostriatal dopamine circuitry; motor deficits that are ameliorated by L-DOPA administration; progressive course of phenotypic manifestations and neurodegeneration; and altered response to L-DOPA treatment dependent on disease stage. In this review we compare the MitoPark mouse to other genetic or toxin-based rodent models of Parkinson's disease.
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Affiliation(s)
- Mats I Ekstrand
- Howard Hughes Medical Institute and Rockefeller University, New York, NY 10065, USA.
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25
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Holt IJ. Zen and the art of mitochondrial DNA maintenance. Trends Genet 2010; 26:103-9. [PMID: 20117854 DOI: 10.1016/j.tig.2009.12.011] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2009] [Revised: 12/29/2009] [Accepted: 12/29/2009] [Indexed: 11/17/2022]
Abstract
Because mitochondrial genes encode proteins essential for aerobic ATP production, mitochondrial DNA defects can cause an energy crisis. These defects fall into two broad categories: primary mutations in mitochondrial DNA and mutations in nuclear genes, whose protein products are involved in mitochondrial DNA maintenance. Evidence is accumulating that both types of defects can cause mitochondrial DNA loss. Hence, regulatory factors, which determine whether mitochondrial DNA molecules are maintained or lost, potentially play a more important role in these disorders than hitherto recognised. Candidates include reactive oxygen species (ROS) and the tumour suppressor p53. The cell might not always be the best judge of when to dispense with the services of mitochondrial DNA, and so interventions that favour its retention could potentially limit the adverse effects of pathological mitochondrial DNAs.
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Affiliation(s)
- Ian J Holt
- MRC Mitochondrial Biology Unit, Wellcome Trust MRC Building Hills Rd, Cambridge, CB2 0XY, UK.
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26
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Tońska K, Sołyga A, Bartnik E. Mitochondria and aging: innocent bystanders or guilty parties? J Appl Genet 2009; 50:55-62. [PMID: 19193984 DOI: 10.1007/bf03195653] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
There are many theories of aging and a number of them encompass the role of mitochondria in this process. Mitochondrial DNA mutations and deletions have been shown to accumulate in many tissues in mammals during aging. However, there is little evidence that these mutations could affect the functioning of aging tissues.
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Affiliation(s)
- K Tońska
- Department of Genetics and Biotechnology, University of Warsaw, Pawinskiego 5a, 02-106 Warsaw, Poland
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27
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Baranowska I, Jäderlund KH, Nennesmo I, Holmqvist E, Heidrich N, Larsson NG, Andersson G, Wagner EGH, Hedhammar Å, Wibom R, Andersson L. Sensory ataxic neuropathy in golden retriever dogs is caused by a deletion in the mitochondrial tRNATyr gene. PLoS Genet 2009; 5:e1000499. [PMID: 19492087 PMCID: PMC2683749 DOI: 10.1371/journal.pgen.1000499] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2009] [Accepted: 04/30/2009] [Indexed: 11/18/2022] Open
Abstract
Sensory ataxic neuropathy (SAN) is a recently identified neurological disorder in golden retrievers. Pedigree analysis revealed that all affected dogs belong to one maternal lineage, and a statistical analysis showed that the disorder has a mitochondrial origin. A one base pair deletion in the mitochondrial tRNA(Tyr) gene was identified at position 5304 in affected dogs after re-sequencing the complete mitochondrial genome of seven individuals. The deletion was not found among dogs representing 18 different breeds or in six wolves, ruling out this as a common polymorphism. The mutation could be traced back to a common ancestor of all affected dogs that lived in the 1970s. We used a quantitative oligonucleotide ligation assay to establish the degree of heteroplasmy in blood and tissue samples from affected dogs and controls. Affected dogs and their first to fourth degree relatives had 0-11% wild-type (wt) sequence, while more distant relatives ranged between 5% and 60% wt sequence and all unrelated golden retrievers had 100% wt sequence. Northern blot analysis showed that tRNA(Tyr) had a 10-fold lower steady-state level in affected dogs compared with controls. Four out of five affected dogs showed decreases in mitochondrial ATP production rates and respiratory chain enzyme activities together with morphological alterations in muscle tissue, resembling the changes reported in human mitochondrial pathology. Altogether, these results provide conclusive evidence that the deletion in the mitochondrial tRNA(Tyr) gene is the causative mutation for SAN.
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Affiliation(s)
- Izabella Baranowska
- Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Karin Hultin Jäderlund
- Department of Clinical Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden
- Department of Companion Animal Clinical Sciences, Norwegian School of Veterinary Science, Oslo, Norway
| | - Inger Nennesmo
- Department of Laboratory Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Erik Holmqvist
- Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
| | - Nadja Heidrich
- Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
| | - Nils-Göran Larsson
- Department of Laboratory Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Göran Andersson
- Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | | | - Åke Hedhammar
- Department of Clinical Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Rolf Wibom
- Department of Laboratory Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Leif Andersson
- Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences, Uppsala, Sweden
- Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
- * E-mail:
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28
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PGC-1alpha in aging and anti-aging interventions. Biochim Biophys Acta Gen Subj 2009; 1790:1059-66. [PMID: 19371772 DOI: 10.1016/j.bbagen.2009.04.005] [Citation(s) in RCA: 110] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2009] [Revised: 04/03/2009] [Accepted: 04/07/2009] [Indexed: 12/25/2022]
Abstract
Deregulation of mitochondrial function is a common feature in multiple aspects of aging. In addition to playing a role in aging-associated disease, decline in mitochondrial energy metabolism is likely to be important in the development of metabolic disease. Furthermore, altered mitochondrial function is a conserved feature in caloric restriction--a dietary intervention that delays aging in diverse species. The transcriptional co-activator PGC-1alpha is a critical regulator of mitochondrial energy metabolism and biogenesis. PGC-1alpha is uniquely poised as a potential target for correcting the effects of age on mitochondrial decline. We describe the cellular and tissue specific mechanisms of PGC-1alpha regulation and illustrate how these pathways may be involved in the aging process.
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29
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Facucho-Oliveira JM, St John JC. The relationship between pluripotency and mitochondrial DNA proliferation during early embryo development and embryonic stem cell differentiation. Stem Cell Rev Rep 2009; 5:140-58. [PMID: 19521804 DOI: 10.1007/s12015-009-9058-0] [Citation(s) in RCA: 172] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2008] [Accepted: 02/04/2009] [Indexed: 01/01/2023]
Abstract
Pluripotent blastomeres of mammalian pre-implantation embryos and embryonic stem cells (ESCs) are characterized by limited oxidative capacity and great reliance on anaerobic respiration. Early pre-implantation embryos and undifferentiated ESCs possess small and immature mitochondria located around the nucleus, have low oxygen consumption and express high levels of glycolytic enzymes. However, as embryonic cells and ESCs lose pluripotency and commit to a specific cell fate, the expression of mtDNA transcription and replication factors is upregulated and the number of mitochondria and mtDNA copies/cell increases. Moreover, upon cellular differentiation, mitochondria acquire an elongated morphology with swollen cristae and dense matrices, migrate into wider cytoplasmic areas and increase the levels of oxygen consumption and ATP production as a result of the activation of the more efficient, aerobic metabolism. Since pluripotency seems to be associated with anaerobic metabolism and a poorly developed mitochondrial network and differentiation leads to activation of mitochondrial biogenesis according to the metabolic requirements of the specific cell type, it is hypothesized that reprogramming of somatic cells towards a pluripotent state, by somatic cell nuclear transfer (SCNT), transcription-induced pluripotency or creation of pluripotent cell hybrids, requires acquisition of mitochondrial properties characteristic of pluripotent blastomeres and ESCs.
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Affiliation(s)
- J M Facucho-Oliveira
- The Mitochondrial and Reproductive Genetics Group, Clinical Sciences Research Institute, Warwick Medical School, University of Warwick, Warwick CV2 2DX, UK
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30
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Torraco A, Diaz F, Vempati UD, Moraes CT. Mouse models of oxidative phosphorylation defects: powerful tools to study the pathobiology of mitochondrial diseases. BIOCHIMICA ET BIOPHYSICA ACTA 2009; 1793:171-80. [PMID: 18601959 PMCID: PMC2652735 DOI: 10.1016/j.bbamcr.2008.06.003] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2008] [Revised: 05/28/2008] [Accepted: 06/04/2008] [Indexed: 01/14/2023]
Abstract
Defects in the oxidative phosphorylation system (OXPHOS) are responsible for a group of extremely heterogeneous and pleiotropic pathologies commonly known as mitochondrial diseases. Although many mutations have been found to be responsible for OXPHOS defects, their pathogenetic mechanisms are still poorly understood. An important contribution to investigate the in vivo function of several mitochondrial proteins and their role in mitochondrial dysfunction, has been provided by mouse models. Thanks to their genetic and physiologic similarity to humans, mouse models represent a powerful tool to investigate the impact of pathological mutations on metabolic pathways. In this review we discuss the main mouse models of mitochondrial disease developed, focusing on the ones that directly affect the OXPHOS system.
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Affiliation(s)
- Alessandra Torraco
- Department of Neurology, University of Miami Miller School of Medicine, 1095 NW 14th Terrace, Miami, FL 33136, USA
| | - Francisca Diaz
- Department of Neurology, University of Miami Miller School of Medicine, 1095 NW 14th Terrace, Miami, FL 33136, USA
| | - Uma D. Vempati
- Department of Neurology, University of Miami Miller School of Medicine, 1095 NW 14th Terrace, Miami, FL 33136, USA
| | - Carlos T. Moraes
- Department of Neurology, University of Miami Miller School of Medicine, 1095 NW 14th Terrace, Miami, FL 33136, USA
- Department of Cell Biology and Anatomy, University of Miami Miller School of Medicine, 1095 NW 14th Terrace, Miami, FL 33136, USA
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31
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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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32
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Vempati UD, Torraco A, Moraes CT. Mouse models of oxidative phosphorylation dysfunction and disease. Methods 2008; 46:241-7. [PMID: 18848991 PMCID: PMC2652743 DOI: 10.1016/j.ymeth.2008.09.008] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2008] [Revised: 08/28/2008] [Accepted: 09/12/2008] [Indexed: 11/23/2022] Open
Abstract
Oxidative phosphorylation (OXPHOS) deficiency results in a number of human diseases, affecting at least one in 5000 of the general population. Altering the function of genes by mutations are central to our understanding their function. Prior to the development of gene targeting, this approach was limited to rare spontaneous mutations that resulted in a phenotype. Since its discovery, targeted mutagenesis of the mouse germline has proved to be a powerful approach to understand the in vivo function of genes. Gene targeting has yielded remarkable understanding of the role of several gene products in the OXPHOS system. We provide a "tool box" of mouse models with OXPHOS defects that could be used to answer diverse scientific questions.
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Affiliation(s)
| | | | - Carlos T. Moraes
- Department of Neurology, University of Miami, USA
- Department of Cell Biology & Anatomy, University of Miami, USA
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