101
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Abstract
Stem cell aging and exhaustion are considered important drivers of organismal aging. Age-associated declines in stem cell function are characterized by metabolic and epigenetic changes. Understanding the mechanisms underlying these changes will likely reveal novel therapeutic targets for ameliorating age-associated phenotypes and for prolonging human healthspan. Recent studies have shown that metabolism plays an important role in regulating epigenetic modifications and that this regulation dramatically affects the aging process. This review focuses on current knowledge regarding the mechanisms of stem cell aging, and the links between cellular metabolism and epigenetic regulation. In addition, we discuss how these interactions sense and respond to environmental stress in order to maintain stem cell homeostasis, and how environmental stimuli regulate stem cell function. Additionally, we highlight recent advances in the development of therapeutic strategies to rejuvenate dysfunctional aged stem cells.
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Affiliation(s)
- Ruotong Ren
- National Clinical Research Center for Geriatric Disorders, Xuanwu Hospital of Capital Medical University, Beijing 100053, China; National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Alejandro Ocampo
- Gene Expression Laboratory, Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Guang-Hui Liu
- National Clinical Research Center for Geriatric Disorders, Xuanwu Hospital of Capital Medical University, Beijing 100053, China; National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China; Beijing Institute for Brain Disorders, Beijing 100069, China.
| | - Juan Carlos Izpisua Belmonte
- Gene Expression Laboratory, Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA.
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102
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Mitochondrial diseases: the contribution of organelle stress responses to pathology. Nat Rev Mol Cell Biol 2017; 19:77-92. [DOI: 10.1038/nrm.2017.66] [Citation(s) in RCA: 264] [Impact Index Per Article: 37.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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103
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Jiang M, Kauppila TES, Motori E, Li X, Atanassov I, Folz-Donahue K, Bonekamp NA, Albarran-Gutierrez S, Stewart JB, Larsson NG. Increased Total mtDNA Copy Number Cures Male Infertility Despite Unaltered mtDNA Mutation Load. Cell Metab 2017; 26:429-436.e4. [PMID: 28768180 DOI: 10.1016/j.cmet.2017.07.003] [Citation(s) in RCA: 73] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/07/2017] [Revised: 06/12/2017] [Accepted: 07/11/2017] [Indexed: 12/22/2022]
Abstract
Mutations of mtDNA cause mitochondrial diseases and are implicated in age-associated diseases and aging. Pathogenic mtDNA mutations are often present in a fraction of all mtDNA copies, and it has been widely debated whether the proportion of mutant genomes or the absolute number of wild-type molecules determines if oxidative phosphorylation (OXPHOS) will be impaired. Here, we have studied the male infertility phenotype of mtDNA mutator mice and demonstrate that decreasing mtDNA copy number worsens mitochondrial aberrations of spermatocytes and spermatids in testes, whereas an increase in mtDNA copy number rescues the fertility phenotype and normalizes testes morphology as well as spermatocyte proteome changes. The restoration of testes function occurs in spite of unaltered total mtDNA mutation load. We thus demonstrate that increased copy number of mtDNA can efficiently ameliorate a severe disease phenotype caused by mtDNA mutations, which has important implications for developing future strategies for treatment of mitochondrial dysfunction.
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Affiliation(s)
- Min Jiang
- Department of Mitochondrial Biology, Max Planck Institute for Biology of Ageing, 50931 Cologne, Germany
| | - Timo Eino Sakari Kauppila
- Department of Mitochondrial Biology, Max Planck Institute for Biology of Ageing, 50931 Cologne, Germany
| | - Elisa Motori
- Department of Mitochondrial Biology, Max Planck Institute for Biology of Ageing, 50931 Cologne, Germany
| | - Xinping Li
- Proteomics Core Facility, Max Planck Institute for Biology of Ageing, 50931 Cologne, Germany
| | - Ilian Atanassov
- Proteomics Core Facility, Max Planck Institute for Biology of Ageing, 50931 Cologne, Germany
| | - Kat Folz-Donahue
- FACS and Imaging Core Facility, Max Planck Institute for Biology of Ageing, 50931 Cologne, Germany
| | - Nina Anna Bonekamp
- Department of Mitochondrial Biology, Max Planck Institute for Biology of Ageing, 50931 Cologne, Germany
| | - Sara Albarran-Gutierrez
- Department of Mitochondrial Biology, Max Planck Institute for Biology of Ageing, 50931 Cologne, Germany
| | - James Bruce Stewart
- Department of Mitochondrial Biology, Max Planck Institute for Biology of Ageing, 50931 Cologne, Germany
| | - Nils-Göran Larsson
- Department of Mitochondrial Biology, Max Planck Institute for Biology of Ageing, 50931 Cologne, Germany; Department of Medical Biochemistry and Biophysics, Karolinska Institutet, 171 77 Stockholm, Sweden.
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104
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Regulatory Role of Redox Balance in Determination of Neural Precursor Cell Fate. Stem Cells Int 2017; 2017:9209127. [PMID: 28804501 PMCID: PMC5540383 DOI: 10.1155/2017/9209127] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Accepted: 06/22/2017] [Indexed: 12/15/2022] Open
Abstract
In 1990s, reports of discovery of a small group of cells capable of proliferation and contribution to formation of new neurons in the central nervous system (CNS) reversed a century-old concept on lack of neurogenesis in the adult mammalian brain. These cells are found in all stages of human life and contribute to normal cellular turnover of the CNS. Therefore, the identity of regulating factors that affect their proliferation and differentiation is a highly noteworthy issue for basic scientists and their clinician counterparts for therapeutic purposes. The cues for such control are embedded in developmental and environmental signaling through a highly regulated tempo-spatial expression of specific transcription factors. Novel findings indicate the importance of reactive oxygen species (ROS) in the regulation of this signaling system. The elusive nature of ROS signaling in many vital processes from cell proliferation to cell death creates a complex literature in this field. Here, we discuss the emerging thoughts on the importance of redox regulation of proliferation and maintenance in mammalian neural stem and progenitor cells under physiological and pathological conditions. The current knowledge on ROS-mediated changes in redox-sensitive proteins that govern the molecular mechanisms in proliferation and differentiation of these cells is reviewed.
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105
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Khacho M, Slack RS. Mitochondrial dynamics in the regulation of neurogenesis: From development to the adult brain. Dev Dyn 2017. [PMID: 28643345 DOI: 10.1002/dvdy.24538] [Citation(s) in RCA: 107] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Mitochondria are classically known to be the cellular energy producers, but a renewed appreciation for these organelles has developed with the accumulating discoveries of additional functions. The importance of mitochondria within the brain has been long known, particularly given the high-energy demanding nature of neurons. The energy demands imposed by neurons require the well-orchestrated morphological adaptation and distribution of mitochondria. Recent studies now reveal the importance of mitochondrial dynamics not only in mature neurons but also during neural development, particularly during the process of neurogenesis and neural stem cell fate decisions. In this review, we will highlight the recent findings that illustrate the importance of mitochondrial dynamics in neurodevelopment and neural stem cell function. Developmental Dynamics 247:47-53, 2018. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Mireille Khacho
- Department of Cellular and Molecular Medicine, University of Ottawa Brain and Mind Research Institute, Ottawa, Ontario, Canada
| | - Ruth S Slack
- Department of Cellular and Molecular Medicine, University of Ottawa Brain and Mind Research Institute, Ottawa, Ontario, Canada
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106
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Origins of mtDNA mutations in ageing. Essays Biochem 2017; 61:325-337. [PMID: 28698307 DOI: 10.1042/ebc20160090] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Revised: 05/24/2017] [Accepted: 05/26/2017] [Indexed: 12/21/2022]
Abstract
MtDNA mutations are one of the hallmarks of ageing and age-related diseases. It is well established that somatic point mutations accumulate in mtDNA of multiple organs and tissues with increasing age and heteroplasmy is universal in mammals. However, the origin of these mutations remains controversial. The long-lasting hypothesis stating that mtDNA mutations emanate from oxidative damage via a self-perpetuating mechanism has been extensively challenged in recent years. Contrary to this initial ascertainment, mtDNA appears to be well protected from action of reactive oxygen species (ROS) through robust protein coating and endomitochondrial microcompartmentalization. Extensive development of scrupulous high-throughput DNA sequencing methods suggests that an imperfect replication process, rather than oxidative lesions are the main sources of mtDNA point mutations, indicating that mtDNA polymerase γ (POLG) might be responsible for the majority of mtDNA mutagenic events. Here, we summarize the recent knowledge in prevention and defence of mtDNA oxidative lesions and discuss the plausible mechanisms of mtDNA point mutation generation and fixation.
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107
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Mitochondrial form, function and signalling in aging. Biochem J 2017; 473:3421-3449. [PMID: 27729586 DOI: 10.1042/bcj20160451] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Accepted: 06/17/2016] [Indexed: 02/07/2023]
Abstract
Aging is often accompanied by a decline in mitochondrial mass and function in different tissues. Additionally, cell resistance to stress is frequently found to be prevented by higher mitochondrial respiratory capacity. These correlations strongly suggest mitochondria are key players in aging and senescence, acting by regulating energy homeostasis, redox balance and signalling pathways central in these processes. However, mitochondria display a wide array of functions and signalling properties, and the roles of these different characteristics are still widely unexplored. Furthermore, differences in mitochondrial properties and responses between tissues and cell types, and how these affect whole body metabolism are also still poorly understood. This review uncovers aspects of mitochondrial biology that have an impact upon aging in model organisms and selected mammalian cells and tissues.
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108
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The mitochondrial respiratory chain is essential for haematopoietic stem cell function. Nat Cell Biol 2017; 19:614-625. [PMID: 28504706 PMCID: PMC5474760 DOI: 10.1038/ncb3529] [Citation(s) in RCA: 215] [Impact Index Per Article: 30.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Accepted: 04/10/2017] [Indexed: 12/12/2022]
Abstract
Adult and fetal hematopoietic stem cells (HSCs) display a glycolytic phenotype, which is required for maintenance of stemness; however, whether mitochondrial respiration is required to maintain HSC function is not known. Here we report that loss of the mitochondrial complex III subunit Rieske iron sulfur protein (RISP) in fetal mouse HSCs allows them to proliferate but impairs their differentiation, resulting in anemia and prenatal death. RISP null fetal HSCs displayed impaired respiration resulting in a decreased NAD+/NADH ratio. RISP null fetal HSCs and progenitors exhibited an increase in both DNA and histone methylation associated with increases in 2-hydroxyglutarate (2-HG), a metabolite known to inhibit DNA and histone demethylases. RISP inactivation in adult HSCs also impaired respiration resulting in loss of quiescence concomitant with severe pancytopenia and lethality. Thus, respiration is dispensable for adult or fetal HSC proliferation, but essential for fetal HSC differentiation and maintenance of adult HSC quiescence.
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109
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Kamel K, Farrell M, O'Brien C. Mitochondrial dysfunction in ocular disease: Focus on glaucoma. Mitochondrion 2017; 35:44-53. [PMID: 28499981 DOI: 10.1016/j.mito.2017.05.004] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Revised: 03/08/2017] [Accepted: 05/08/2017] [Indexed: 12/21/2022]
Abstract
Mitochondrial dysfunction commonly presents with ocular findings as a part of a systemic disorder. These ophthalmic manifestations can be the first sign of a mitochondrial abnormality, which highlights the key role of a comprehensive ophthalmic assessment. On the other hand, a number of visually disabling genetic and acquired eye diseases with no curative treatment show abnormal mitochondrial function. Recent advances in mitochondrial research have improved our understanding of previously unexplained ocular disorders utilising better diagnostic approaches. Further studies on mitochondrial dysfunction and novel modalities of treatment will help to improve outcomes of these conditions. In this review article we discuss the clinical picture of common mitochondrial-related eye diseases, diagnostic approaches and possible treatment options including a very recent interesting report about gene therapy, with a particular focus on glaucoma.
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Affiliation(s)
- Khalid Kamel
- Institute of Ophthalmology, Mater Misericordiae University Hospital, Dublin, Ireland
| | | | - Colm O'Brien
- Institute of Ophthalmology, Mater Misericordiae University Hospital, Dublin, Ireland.
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110
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Bioenergetic Changes during Differentiation of Human Embryonic Stem Cells along the Hepatic Lineage. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2017; 2017:5080128. [PMID: 28265337 PMCID: PMC5317109 DOI: 10.1155/2017/5080128] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/18/2016] [Revised: 12/19/2016] [Accepted: 01/10/2017] [Indexed: 12/12/2022]
Abstract
Mitochondrial dysfunction has been demonstrated to result in premature aging due to its effects on stem cells. Nevertheless, a full understanding of the role of mitochondrial bioenergetics through differentiation is still lacking. Here we show the bioenergetics profile of human stem cells of embryonic origin differentiating along the hepatic lineage. Our study reveals especially the transition between hepatic specification and hepatic maturation as dependent on mitochondrial respiration and demonstrates that even though differentiating cells are primarily dependent on glycolysis until induction of hepatocyte maturation, oxidative phosphorylation is essential at all stages of differentiation.
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111
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Someya S, Kujoth GC, Kim MJ, Hacker TA, Vermulst M, Weindruch R, Prolla TA. Effects of calorie restriction on the lifespan and healthspan of POLG mitochondrial mutator mice. PLoS One 2017; 12:e0171159. [PMID: 28158260 PMCID: PMC5291490 DOI: 10.1371/journal.pone.0171159] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2016] [Accepted: 01/16/2017] [Indexed: 01/21/2023] Open
Abstract
Mitochondrial DNA (mtDNA) mutations are thought to have a causative role in age-related pathologies. We have shown previously that mitochondrial mutator mice (PolgD257A/D257A), harboring a proofreading-deficient version of the mtDNA polymerase gamma (POLG), accumulate mtDNA mutations in multiple tissues and display several features of accelerated aging. Calorie restriction (CR) is known to delay the onset of age-related diseases and to extend the lifespan of a variety of species, including rodents. In the current study we investigated the effects of CR on the lifespan and healthspan of mitochondrial mutator mice. Long-term CR did not increase the median or maximum lifespan of PolgD257A/D257A mice. Furthermore, CR did not reduce mtDNA deletions in the heart and muscle, accelerated sarcopenia, testicular atrophy, nor improve the alterations in cardiac parameters that are present in aged mitochondrial mutator mice. Therefore, our findings suggest that accumulation of mtDNA mutations may interfere with the beneficial action of CR in aging retardation.
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Affiliation(s)
- Shinichi Someya
- Department of Aging and Geriatric Research, University of Florida, Gainesville, Florida, United States of America
| | - Gregory C. Kujoth
- Department of Neurological Surgery, University of Wisconsin, Madison, Wisconsin, United States of America
| | - Mi-Jung Kim
- Department of Aging and Geriatric Research, University of Florida, Gainesville, Florida, United States of America
| | - Timothy A. Hacker
- Department of Medicine, University of Wisconsin, Madison, Wisconsin, United States of America
| | - Marc Vermulst
- Center for Mitochondrial and Epigenomic Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Richard Weindruch
- Veterans Administration Hospital, Geriatric Research, Education and Clinical Center, University of Wisconsin, Madison, Wisconsin, United States of America
| | - Tomas A. Prolla
- Departments of Genetics & Medical Genetics, University of Wisconsin, Madison, Wisconsin, United States of America
- * E-mail:
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112
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Beckervordersandforth R, Ebert B, Schäffner I, Moss J, Fiebig C, Shin J, Moore DL, Ghosh L, Trinchero MF, Stockburger C, Friedland K, Steib K, von Wittgenstein J, Keiner S, Redecker C, Hölter SM, Xiang W, Wurst W, Jagasia R, Schinder AF, Ming GL, Toni N, Jessberger S, Song H, Lie DC. Role of Mitochondrial Metabolism in the Control of Early Lineage Progression and Aging Phenotypes in Adult Hippocampal Neurogenesis. Neuron 2017; 93:560-573.e6. [PMID: 28111078 DOI: 10.1016/j.neuron.2016.12.017] [Citation(s) in RCA: 185] [Impact Index Per Article: 26.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2015] [Revised: 08/06/2016] [Accepted: 11/23/2016] [Indexed: 12/20/2022]
Abstract
Precise regulation of cellular metabolism is hypothesized to constitute a vital component of the developmental sequence underlying the life-long generation of hippocampal neurons from quiescent neural stem cells (NSCs). The identity of stage-specific metabolic programs and their impact on adult neurogenesis are largely unknown. We show that the adult hippocampal neurogenic lineage is critically dependent on the mitochondrial electron transport chain and oxidative phosphorylation machinery at the stage of the fast proliferating intermediate progenitor cell. Perturbation of mitochondrial complex function by ablation of the mitochondrial transcription factor A (Tfam) reproduces multiple hallmarks of aging in hippocampal neurogenesis, whereas pharmacological enhancement of mitochondrial function ameliorates age-associated neurogenesis defects. Together with the finding of age-associated alterations in mitochondrial function and morphology in NSCs, these data link mitochondrial complex function to efficient lineage progression of adult NSCs and identify mitochondrial function as a potential target to ameliorate neurogenesis-defects in the aging hippocampus.
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Affiliation(s)
- Ruth Beckervordersandforth
- Institute of Biochemistry, Emil Fischer Center, Friedrich-Alexander Universität Erlangen-Nürnberg, 91054 Erlangen, Germany.
| | - Birgit Ebert
- Institute of Biochemistry, Emil Fischer Center, Friedrich-Alexander Universität Erlangen-Nürnberg, 91054 Erlangen, Germany; Institute of Developmental Genetics, Helmholtz Center Munich, German Research Center for Environmental Health, 85764 Munich-Neuherberg, Germany
| | - Iris Schäffner
- Institute of Biochemistry, Emil Fischer Center, Friedrich-Alexander Universität Erlangen-Nürnberg, 91054 Erlangen, Germany
| | - Jonathan Moss
- Department of Fundamental Neuroscience, University of Lausanne, 1005 Lausanne, Switzerland
| | - Christian Fiebig
- Institute of Biochemistry, Emil Fischer Center, Friedrich-Alexander Universität Erlangen-Nürnberg, 91054 Erlangen, Germany
| | - Jaehoon Shin
- Institute for Cell Engineering, Department of Neurology, The Solomon Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Darcie L Moore
- Brain Research Institute, Faculty of Medicine and Science, University of Zurich, 8057 Zurich, Switzerland
| | - Laboni Ghosh
- Brain Research Institute, Faculty of Medicine and Science, University of Zurich, 8057 Zurich, Switzerland
| | - Mariela F Trinchero
- Laboratory of Neuronal Plasticity, Leloir Institute (IIBBA, CONICET), C1405BWE Buenos Aires, Argentina
| | - Carola Stockburger
- Molecular and Clinical Pharmacy, Friedrich-Alexander Universität Erlangen-Nürnberg, 91054 Erlangen, Germany
| | - Kristina Friedland
- Molecular and Clinical Pharmacy, Friedrich-Alexander Universität Erlangen-Nürnberg, 91054 Erlangen, Germany
| | - Kathrin Steib
- Institute of Developmental Genetics, Helmholtz Center Munich, German Research Center for Environmental Health, 85764 Munich-Neuherberg, Germany
| | - Julia von Wittgenstein
- Institute of Biochemistry, Emil Fischer Center, Friedrich-Alexander Universität Erlangen-Nürnberg, 91054 Erlangen, Germany
| | - Silke Keiner
- Hans Berger Department of Neurology, Jena University Hospital, 07747 Jena, Germany
| | - Christoph Redecker
- Hans Berger Department of Neurology, Jena University Hospital, 07747 Jena, Germany
| | - Sabine M Hölter
- Institute of Developmental Genetics, Helmholtz Center Munich, German Research Center for Environmental Health, 85764 Munich-Neuherberg, Germany
| | - Wei Xiang
- Institute of Biochemistry, Emil Fischer Center, Friedrich-Alexander Universität Erlangen-Nürnberg, 91054 Erlangen, Germany
| | - Wolfgang Wurst
- Institute of Developmental Genetics, Helmholtz Center Munich, German Research Center for Environmental Health, 85764 Munich-Neuherberg, Germany
| | - Ravi Jagasia
- Institute of Developmental Genetics, Helmholtz Center Munich, German Research Center for Environmental Health, 85764 Munich-Neuherberg, Germany; F. Hoffmann-La Roche Ltd, CNS Discovery; Pharma Research and Early Development, 4070 Basel, Switzerland
| | - Alejandro F Schinder
- Laboratory of Neuronal Plasticity, Leloir Institute (IIBBA, CONICET), C1405BWE Buenos Aires, Argentina
| | - Guo-Li Ming
- Institute for Cell Engineering, Department of Neurology, The Solomon Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Nicolas Toni
- Department of Fundamental Neuroscience, University of Lausanne, 1005 Lausanne, Switzerland
| | - Sebastian Jessberger
- Brain Research Institute, Faculty of Medicine and Science, University of Zurich, 8057 Zurich, Switzerland
| | - Hongjun Song
- Institute for Cell Engineering, Department of Neurology, The Solomon Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - D Chichung Lie
- Institute of Biochemistry, Emil Fischer Center, Friedrich-Alexander Universität Erlangen-Nürnberg, 91054 Erlangen, Germany.
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113
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Abstract
Mitochondria were first postulated to contribute to aging more than 40 years ago. During the following decades, multiple lines of evidence in model organisms and humans showed that impaired mitochondrial function can contribute to age-associated disease phenotypes and aging. However, in contrast to the original theory favoring oxidative damage as a cause for mtDNA mutations, there are now strong data arguing that most mammalian mtDNA mutations originate as replication errors made by the mtDNA polymerase. Currently, a substantial amount of mitochondrial research is focused on finding ways to either remove or counteract the effects of mtDNA mutations with the hope of extending the human health- and lifespan. This review summarizes the current knowledge regarding the formation of mtDNA mutations and their impact on mitochondrial function. We also critically discuss proposed pathways interlinked with mammalian mtDNA mutations and suggest future research strategies to elucidate the role of mtDNA mutations in aging.
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Affiliation(s)
- Timo E S Kauppila
- Department of Mitochondrial Biology, Max Planck Institute for Biology of Ageing, D-50931 Cologne, Germany
| | - Johanna H K Kauppila
- Department of Mitochondrial Biology, Max Planck Institute for Biology of Ageing, D-50931 Cologne, Germany
| | - Nils-Göran Larsson
- Department of Mitochondrial Biology, Max Planck Institute for Biology of Ageing, D-50931 Cologne, Germany; Department of Medical Biochemistry and Biophysics, Karolinska Institutet, 171 77 Stockholm, Sweden.
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114
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DeBalsi KL, Hoff KE, Copeland WC. Role of the mitochondrial DNA replication machinery in mitochondrial DNA mutagenesis, aging and age-related diseases. Ageing Res Rev 2017; 33:89-104. [PMID: 27143693 DOI: 10.1016/j.arr.2016.04.006] [Citation(s) in RCA: 117] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Revised: 04/19/2016] [Accepted: 04/19/2016] [Indexed: 12/19/2022]
Abstract
As regulators of bioenergetics in the cell and the primary source of endogenous reactive oxygen species (ROS), dysfunctional mitochondria have been implicated for decades in the process of aging and age-related diseases. Mitochondrial DNA (mtDNA) is replicated and repaired by nuclear-encoded mtDNA polymerase γ (Pol γ) and several other associated proteins, which compose the mtDNA replication machinery. Here, we review evidence that errors caused by this replication machinery and failure to repair these mtDNA errors results in mtDNA mutations. Clonal expansion of mtDNA mutations results in mitochondrial dysfunction, such as decreased electron transport chain (ETC) enzyme activity and impaired cellular respiration. We address the literature that mitochondrial dysfunction, in conjunction with altered mitochondrial dynamics, is a major driving force behind aging and age-related diseases. Additionally, interventions to improve mitochondrial function and attenuate the symptoms of aging are examined.
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Affiliation(s)
- Karen L DeBalsi
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA
| | - Kirsten E Hoff
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA
| | - William C Copeland
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA.
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115
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Pinto M, Pickrell AM, Wang X, Bacman SR, Yu A, Hida A, Dillon LM, Morton PD, Malek TR, Williams SL, Moraes CT. Transient mitochondrial DNA double strand breaks in mice cause accelerated aging phenotypes in a ROS-dependent but p53/p21-independent manner. Cell Death Differ 2016; 24:288-299. [PMID: 27911443 DOI: 10.1038/cdd.2016.123] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Revised: 09/16/2016] [Accepted: 09/26/2016] [Indexed: 12/20/2022] Open
Abstract
We observed that the transient induction of mtDNA double strand breaks (DSBs) in cultured cells led to activation of cell cycle arrest proteins (p21/p53 pathway) and decreased cell growth, mediated through reactive oxygen species (ROS). To investigate this process in vivo we developed a mouse model where we could transiently induce mtDNA DSBs ubiquitously. This transient mtDNA damage in mice caused an accelerated aging phenotype, preferentially affecting proliferating tissues. One of the earliest phenotypes was accelerated thymus shrinkage by apoptosis and differentiation into adipose tissue, mimicking age-related thymic involution. This phenotype was accompanied by increased ROS and activation of cell cycle arrest proteins. Treatment with antioxidants improved the phenotype but the knocking out of p21 or p53 did not. Our results demonstrate that transient mtDNA DSBs can accelerate aging of certain tissues by increasing ROS. Surprisingly, this mtDNA DSB-associated senescence phenotype does not require p21/p53, even if this pathway is activated in the process.
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Affiliation(s)
- Milena Pinto
- Department of Neurology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Alicia M Pickrell
- Neuroscience Graduate Program, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Xiao Wang
- Graduate Program in Cancer Biology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Sandra R Bacman
- Department of Neurology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Aixin Yu
- Department of Microbiology and Immunology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Aline Hida
- Department of Neurology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Lloye M Dillon
- Department of Cell Biology and Anatomy, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Paul D Morton
- Department of Neurosurgery, University of Miami Miller School of Medicine, Miami, FL 33136, USA.,Center for Neuroscience Research, Children's National Medical Center, Washington, DC 20010, USA
| | - Thomas R Malek
- Department of Microbiology and Immunology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Siôn L Williams
- Department of Neurology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Carlos T Moraes
- Department of Neurology, University of Miami Miller School of Medicine, Miami, FL 33136, USA.,Neuroscience Graduate Program, University of Miami Miller School of Medicine, Miami, FL 33136, USA.,Graduate Program in Cancer Biology, University of Miami Miller School of Medicine, Miami, FL 33136, USA.,Department of Cell Biology and Anatomy, University of Miami Miller School of Medicine, Miami, FL 33136, USA
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116
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Nivet E. Modifiers of Neural Stem Cells and Aging: Pulling the Trigger of a Neurogenic Decline. CURRENT STEM CELL REPORTS 2016. [DOI: 10.1007/s40778-016-0047-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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117
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Amelioration of premature aging in mtDNA mutator mouse by exercise: the interplay of oxidative stress, PGC-1α, p53, and DNA damage. A hypothesis. Curr Opin Genet Dev 2016; 38:127-132. [PMID: 27497229 DOI: 10.1016/j.gde.2016.06.011] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Revised: 05/25/2016] [Accepted: 06/21/2016] [Indexed: 11/23/2022]
Abstract
The mtDNA mutator mouse lacks the proofreading capacity of the sole mtDNA polymerase, leading to accumulation of somatic mtDNA mutations, and a profound premature aging phenotype including elevated oxidative stress and apoptosis, and reduced mitochondrial function. We have previously reported that endurance exercise alleviates the aging phenotype in the mutator mice, reduces oxidative stress, and enhances mitochondrial biogenesis. Here we summarize our findings, with the emphasis on the central role of p53 in these adaptations. We demonstrate that mtDNA in sedentary and exercised PolG mice carry similar amounts of mutations in muscle, but in addition to that sedentary mice have more non-mutational damage, which is mitigated by exercise. It follows therefore that the profound alleviation of the mtDNA mutator phenotype in muscle by exercise may not require a reduction in mtDNA mutational load, but rather a decrease of mtDNA damage and/or oxidative stress. We further hypothesize that the observed 'alleviation without a reduction of mutational load' implies that the oxidative stress in PolG muscle is maintained, at least in part, by the 'malicious cycle', a hypothetical positive feedback potentially driven by the 'transcriptional mutagenesis', that is the conversion of chemically modified nucleotides into mutant RNA bases by the mitochondrial RNA polymerase.
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118
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Abstract
A decline in mitochondrial quality and activity has been associated with normal aging and correlated with the development of a wide range of age-related diseases. Here, we review the evidence that a decline in mitochondria function contributes to aging. In particular, we discuss how mitochondria contribute to specific aspects of the aging process, including cellular senescence, chronic inflammation, and the age-dependent decline in stem cell activity. Signaling pathways regulating the mitochondrial unfolded protein response and mitophagy are also reviewed, with particular emphasis placed on how these pathways might, in turn, regulate longevity. Taken together, these observations suggest that mitochondria influence or regulate a number of key aspects of aging and suggest that strategies directed at improving mitochondrial quality and function might have far-reaching beneficial effects.
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Affiliation(s)
- Nuo Sun
- Center for Molecular Medicine, National Heart, Lung and Blood Institute, NIH, Bethesda, MD 20892, USA
| | - Richard J Youle
- Biochemistry Section, Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD 20892, USA.
| | - Toren Finkel
- Center for Molecular Medicine, National Heart, Lung and Blood Institute, NIH, Bethesda, MD 20892, USA.
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119
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Chandel NS, Jasper H, Ho TT, Passegué E. Metabolic regulation of stem cell function in tissue homeostasis and organismal ageing. Nat Cell Biol 2016; 18:823-32. [PMID: 27428307 DOI: 10.1038/ncb3385] [Citation(s) in RCA: 208] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Accepted: 06/08/2016] [Indexed: 12/11/2022]
Abstract
Many tissues and organ systems in metazoans have the intrinsic capacity to regenerate, which is driven and maintained largely by tissue-resident somatic stem cell populations. Ageing is accompanied by a deregulation of stem cell function and a decline in regenerative capacity, often resulting in degenerative diseases. The identification of strategies to maintain stem cell function and regulation is therefore a promising avenue to allay a wide range of age-related diseases. Studies in various organisms have revealed a central role for metabolic pathways in the regulation of stem cell function. Ageing is associated with extensive metabolic changes, and interventions that influence cellular metabolism have long been recognized as robust lifespan-extending measures. In this Review, we discuss recent advances in our understanding of the metabolic control of stem cell function, and how stem cell metabolism relates to homeostasis and ageing.
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Affiliation(s)
- Navdeep S Chandel
- Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611-2909, USA
| | - Heinrich Jasper
- The Buck Institute for Research on Aging, Novato, California 94945-1400, USA, and the Leibniz Institute on Aging-Fritz Lipmann Institute, Jena 07745, Germany
| | - Theodore T Ho
- Department of Medicine, Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California San Francisco, California 94143-0667, USA
| | - Emmanuelle Passegué
- Department of Medicine, Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California San Francisco, California 94143-0667, USA
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120
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Abstract
This commentary inaugurates a new review series in EMBO Molecular Medicine focused on mitochondrial diseases. This area of medicine, which actually encompasses most disease areas, has long since come of age and is now positioned for the next leap toward the development of effective therapies. The aims of the review series are to offer a comprehensive overview of this exciting area of medicine and research and to provide timely discussions for clinicians and investigators on the new discoveries elucidating how mitochondrial metabolism contributes to an expanding group of complex, heterogeneous, and difficult-to-tackle diseases.
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Affiliation(s)
- Anu Suomalainen
- Research Programs Unit, Molecular Neurology, Helsinki, Finland Neuroscience Center, University of Helsinki, Helsinki, Finland Department of Neurology, Helsinki University Central Hospital, Helsinki, Finland
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121
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Roh J, Rhee J, Chaudhari V, Rosenzweig A. The Role of Exercise in Cardiac Aging: From Physiology to Molecular Mechanisms. Circ Res 2016; 118:279-95. [PMID: 26838314 DOI: 10.1161/circresaha.115.305250] [Citation(s) in RCA: 90] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Aging induces structural and functional changes in the heart that are associated with increased risk of cardiovascular disease and impaired functional capacity in the elderly. Exercise is a diagnostic and therapeutic tool, with the potential to provide insights into clinical diagnosis and prognosis, as well as the molecular mechanisms by which aging influences cardiac physiology and function. In this review, we first provide an overview of how aging impacts the cardiac response to exercise, and the implications this has for functional capacity in older adults. We then review the underlying molecular mechanisms by which cardiac aging contributes to exercise intolerance, and conversely how exercise training can potentially modulate aging phenotypes in the heart. Finally, we highlight the potential use of these exercise models to complement models of disease in efforts to uncover new therapeutic targets to prevent or treat heart disease in the aging population.
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Affiliation(s)
- Jason Roh
- From the Cardiovascular Division (J. Roh, J. Rhee, V.C., A.R.) and Department of Anesthesiology, Critical Care, and Pain Medicine (J. Rhee), Massachusetts General Hospital and Harvard Medical School, Boston
| | - James Rhee
- From the Cardiovascular Division (J. Roh, J. Rhee, V.C., A.R.) and Department of Anesthesiology, Critical Care, and Pain Medicine (J. Rhee), Massachusetts General Hospital and Harvard Medical School, Boston
| | - Vinita Chaudhari
- From the Cardiovascular Division (J. Roh, J. Rhee, V.C., A.R.) and Department of Anesthesiology, Critical Care, and Pain Medicine (J. Rhee), Massachusetts General Hospital and Harvard Medical School, Boston
| | - Anthony Rosenzweig
- From the Cardiovascular Division (J. Roh, J. Rhee, V.C., A.R.) and Department of Anesthesiology, Critical Care, and Pain Medicine (J. Rhee), Massachusetts General Hospital and Harvard Medical School, Boston.
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122
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Hämäläinen RH. Mitochondria and mtDNA integrity in stem cell function and differentiation. Curr Opin Genet Dev 2016; 38:83-89. [PMID: 27219871 DOI: 10.1016/j.gde.2016.04.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Revised: 04/21/2016] [Accepted: 04/24/2016] [Indexed: 01/19/2023]
Abstract
Stem cells require tight control of energy metabolism to maintain homeostasis. They possess few immature mitochondria, repress mitochondrial respiration and instead use glycolysis to produce energy, yet mitochondrial defects can lead to severe stem cell dysfunction. Recent studies have shown that mitochondrial mass, function and integrity are tightly controlled in stem cells and the integrity of the mitochondrial genome is equally important to nuclear genome integrity for proper stem cell homeostasis. Mitochondria are now considered central in regulating stem cell function and governing cellular fate choices. This review will summarize recent advances highlighting the importance of mitochondrial integrity in stem cells.
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Affiliation(s)
- Riikka H Hämäläinen
- Department of Neurobiology, A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland.
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123
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Bhatia-Dey N, Kanherkar RR, Stair SE, Makarev EO, Csoka AB. Cellular Senescence as the Causal Nexus of Aging. Front Genet 2016; 7:13. [PMID: 26904101 PMCID: PMC4751276 DOI: 10.3389/fgene.2016.00013] [Citation(s) in RCA: 96] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Accepted: 01/26/2016] [Indexed: 12/15/2022] Open
Abstract
In this paper we present cellular senescence as the ultimate driver of the aging process, as a "causal nexus" that bridges microscopic subcellular damage with the phenotypic, macroscopic effect of aging. It is important to understand how the various types of subcellular damage correlated with the aging process lead to the larger, visible effects of anatomical aging. While it has always been assumed that subcellular damage (cause) results in macroscopic aging (effect), the bridging link between the two has been hard to define. Here, we propose that this bridge, which we term the "causal nexus", is in fact cellular senescence. The subcellular damage itself does not directly cause the visible signs of aging, but rather, as the damage accumulates and reaches a critical mass, cells cease to proliferate and acquire the deleterious "senescence-associated secretory phenotype" (SASP) which then leads to the macroscopic consequences of tissue breakdown to create the physiologically aged phenotype. Thus senescence is a precondition for anatomical aging, and this explains why aging is a gradual process that remains largely invisible during most of its progression. The subcellular damage includes shortening of telomeres, damage to mitochondria, aneuploidy, and DNA double-strand breaks triggered by various genetic, epigenetic, and environmental factors. Damage pathways acting in isolation or in concert converge at the causal nexus of cellular senescence. In each species some types of damage can be more causative than in others and operate at a variable pace; for example, telomere erosion appears to be a primary cause in human cells, whereas activation of tumor suppressor genes is more causative in rodents. Such species-specific mechanisms indicate that despite different initial causes, most of aging is traced to a single convergent causal nexus: senescence. The exception is in some invertebrate species that escape senescence, and in non-dividing cells such as neurons, where senescence still occurs, but results in the SASP rather than loss of proliferation plus SASP. Aging currently remains an inevitable endpoint for most biological organisms, but the field of cellular senescence is primed for a renaissance and as our understanding of aging is refined, strategies capable of decelerating the aging process will emerge.
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Affiliation(s)
- Naina Bhatia-Dey
- Epigenetics Laboratory, Department of Anatomy, Howard University Washington, DC, USA
| | - Riya R Kanherkar
- Epigenetics Laboratory, Department of Anatomy, Howard University Washington, DC, USA
| | | | - Evgeny O Makarev
- Vision Genomics, LLCWashington, DC, USA; InSilico Medicine, Emerging Technology Center, Johns Hopkins UniversityBaltimore, MD, USA
| | - Antonei B Csoka
- Epigenetics Laboratory, Department of Anatomy, Howard UniversityWashington, DC, USA; InSilico Medicine, Emerging Technology Center, Johns Hopkins UniversityBaltimore, MD, USA
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124
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Min-Wen JC, Jun-Hao ET, Shyh-Chang N. Stem cell mitochondria during aging. Semin Cell Dev Biol 2016; 52:110-8. [PMID: 26851627 DOI: 10.1016/j.semcdb.2016.02.005] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Revised: 01/28/2016] [Accepted: 02/01/2016] [Indexed: 01/06/2023]
Abstract
Mitochondria are the central hubs of cellular metabolism, equipped with their own mitochondrial DNA (mtDNA) blueprints to direct part of the programming of mitochondrial oxidative metabolism and thus reactive oxygen species (ROS) levels. In stem cells, many stem cell factors governing the intricate balance between self-renewal and differentiation have been found to directly regulate mitochondrial processes to control stem cell behaviors during tissue regeneration and aging. Moreover, numerous nutrient-sensitive signaling pathways controlling organismal longevity in an evolutionarily conserved fashion also influence stem cell-mediated tissue homeostasis during aging via regulation of stem cell mitochondria. At the genomic level, it has been demonstrated that heritable mtDNA mutations and variants affect mammalian stem cell homeostasis and influence the risk for human degenerative diseases during aging. Because such a multitude of stem cell factors and signaling pathways ultimately converge on the mitochondria as the primary mechanism to modulate cellular and organismal longevity, it would be most efficacious to develop technologies to therapeutically target and direct mitochondrial repair in stem cells, as a unified strategy to combat aging-related degenerative diseases in the future.
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Affiliation(s)
- Jason Chua Min-Wen
- Stem Cell & Regenerative Biology, Genome Institute of Singapore, 60 Biopolis St, S138672, Singapore
| | - Elwin Tan Jun-Hao
- Stem Cell & Regenerative Biology, Genome Institute of Singapore, 60 Biopolis St, S138672, Singapore
| | - Ng Shyh-Chang
- Stem Cell & Regenerative Biology, Genome Institute of Singapore, 60 Biopolis St, S138672, Singapore.
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125
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Mitchell SJ, Scheibye-Knudsen M, Longo DL, de Cabo R. Animal models of aging research: implications for human aging and age-related diseases. Annu Rev Anim Biosci 2016; 3:283-303. [PMID: 25689319 DOI: 10.1146/annurev-animal-022114-110829] [Citation(s) in RCA: 181] [Impact Index Per Article: 22.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Aging is characterized by an increasing morbidity and functional decline that eventually results in the death of an organism. Aging is the largest risk factor for numerous human diseases, and understanding the aging process may thereby facilitate the development of new treatments for age-associated diseases. The use of humans in aging research is complicated by many factors, including ethical issues; environmental and social factors; and perhaps most importantly, their long natural life span. Although cellular models of human disease provide valuable mechanistic information, they are limited in that they may not replicate the in vivo biology. Almost all organisms age, and thus animal models can be useful for studying aging. Herein, we review some of the major models currently used in aging research and discuss their benefits and pitfalls, including interventions known to extend life span and health span. Finally, we conclude by discussing the future of animal models in aging research.
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126
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Cardiac Response to Oxidative Stress Induced by Mitochondrial Dysfunction. Rev Physiol Biochem Pharmacol 2016; 170:101-27. [DOI: 10.1007/112_2015_5004] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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127
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Yun MH. Changes in Regenerative Capacity through Lifespan. Int J Mol Sci 2015; 16:25392-432. [PMID: 26512653 PMCID: PMC4632807 DOI: 10.3390/ijms161025392] [Citation(s) in RCA: 115] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Revised: 09/30/2015] [Accepted: 09/30/2015] [Indexed: 12/14/2022] Open
Abstract
Most organisms experience changes in regenerative abilities through their lifespan. During aging, numerous tissues exhibit a progressive decline in homeostasis and regeneration that results in tissue degeneration, malfunction and pathology. The mechanisms responsible for this decay are both cell intrinsic, such as cellular senescence, as well as cell-extrinsic, such as changes in the regenerative environment. Understanding how these mechanisms impact on regenerative processes is essential to devise therapeutic approaches to improve tissue regeneration and extend healthspan. This review offers an overview of how regenerative abilities change through lifespan in various organisms, the factors that underlie such changes and the avenues for therapeutic intervention. It focuses on established models of mammalian regeneration as well as on models in which regenerative abilities do not decline with age, as these can deliver valuable insights for our understanding of the interplay between regeneration and aging.
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Affiliation(s)
- Maximina H Yun
- Institute of Structural and Molecular Biology, Division of Biosciences, University College London, Gower Street, London WC1E 6BT, UK.
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128
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Shlush LI, Zandi S, Itzkovitz S, Schuh AC. Aging, clonal hematopoiesis and preleukemia: not just bad luck? Int J Hematol 2015; 102:513-22. [PMID: 26440972 DOI: 10.1007/s12185-015-1870-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Revised: 09/09/2015] [Accepted: 09/18/2015] [Indexed: 12/14/2022]
Abstract
Chronological human aging is associated with a number of changes in the hematopoietic system, occurring at many levels from stem to mature cells, and the marrow microenvironment as well. This review will focus mainly on the aging of hematopoietic stem and progenitor cells (HSPCs), and on the associated increases in the incidence of hematological malignancies. HSPCs manifest reduced function and acquire molecular changes with chronological aging. Furthermore, while for many years it has been known that the human hematopoietic system becomes increasingly clonal with chronological aging (clonal hematopoiesis), only in the last few years has it become clear that clonal hematopoiesis may result from the accumulation of preleukemic mutations in HSPCs. Such mutations confer a selective advantage that leads to clonal hematopoiesis, and that may occasionally result in the development of leukemia, and define the existence of both preleukemic stem cells, and of 'preleukemia' as a clinical entity. While it is well appreciated that clonal hematopoiesis is very common in the elderly, several questions remain unanswered: why and how does clonal hematopoiesis develop? How is clonal hematopoiesis related to the age-related changes observed in the hematopoietic system? And why do only some individuals with clonal hematopoiesis develop leukemia?
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Affiliation(s)
- Liran I Shlush
- Department of Medical Oncology and Hematology, Princess Margaret Cancer Centre, University Health Network (UHN), 610 University Ave, Toronto, ON, M5G 2M9, Canada. .,Weizmann Institute of Science, Rehovot, Israel.
| | - Sasan Zandi
- Department of Medical Oncology and Hematology, Princess Margaret Cancer Centre, University Health Network (UHN), 610 University Ave, Toronto, ON, M5G 2M9, Canada
| | | | - Andre C Schuh
- Department of Medical Oncology and Hematology, Princess Margaret Cancer Centre, University Health Network (UHN), 610 University Ave, Toronto, ON, M5G 2M9, Canada
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129
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Song IS, Jeong YJ, Jeong SH, Heo HJ, Kim HK, Bae KB, Park YH, Kim SU, Kim JM, Kim N, Ko KS, Rhee BD, Han J. FOXM1-Induced PRX3 Regulates Stemness and Survival of Colon Cancer Cells via Maintenance of Mitochondrial Function. Gastroenterology 2015; 149:1006-16.e9. [PMID: 26091938 DOI: 10.1053/j.gastro.2015.06.007] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/16/2014] [Revised: 06/01/2015] [Accepted: 06/03/2015] [Indexed: 12/19/2022]
Abstract
BACKGROUND & AIMS Reagents designed to target cancer stem cells (CSCs) could reduce tumor growth, recurrence, and metastasis. We investigated the mitochondrial features of CSCs. METHODS Colon adenocarcinoma fragments were obtained from 8 patients during surgery at Busan Paik Hospital in Korea. We used immunohistochemistry and quantitative polymerase chain reaction to compare expression of mitochondrial peroxiredoxin 3 (PRX3) in CD133(+)CD44(+) Lgr5(+)cells (CSCs) vs CD133(-)CD44(-)Lgr5(-) colon tumor cells (non-CSCs). Cell survival and expression of mitochondrial-related genes were analyzed in the presence of 5-fluorouracil and/or antimycin A. We used small-interfering and short-hairpin RNAs and an overexpression vector to study PRX3, which functions in the mitochondria. CD133(+) cells with PRX3 knockdown or overexpressing PRX3 were grown as xenograft tumors in immunocompromised mice. Metastasis was studied after injection of tumor cells in spleens of mice. We used chromatin immunoprecipitation and reporter assays to characterize transcriptional regulation of PRX3 by forkhead box protein 1. RESULTS CSCs had a higher mitochondrial membrane potential and increased levels of adenosine triphosphate, Ca(2+), reactive oxygen species, and oxygen consumption than non-CSCs. Levels of PRX3 were increased in colon CSCs compared with non-CSCs. PRX3 knockdown reduced the viability of CSCs, but non non-CSCs, by inducing mitochondrial dysfunction. PRX3 knockdown reduced growth of CSCs as xenograft tumors or metastases in mice. The expression of FOXM1 activated transcription of PRX3 and expression of CD133 in colon CSCs. CONCLUSIONS Human colon CSCs have increased mitochondrial function compared with colon tumor cells without stem cell properties. Colon CSCs overexpress the mitochondrial gene PRX3, which is required for maintenance of mitochondrial function and tumorigenesis, and is regulated by forkhead box protein 1, which also regulates expression of CD133 in these cells. These proteins might be therapeutic targets for colorectal cancer.
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Affiliation(s)
- In-Sung Song
- National Research Laboratory for Mitochondrial Signaling, Department of Physiology, College of Medicine, Cardiovascular and Metabolic Disease Center, Inje University, Busan, Korea
| | - Yu Jeong Jeong
- National Research Laboratory for Mitochondrial Signaling, Department of Physiology, College of Medicine, Cardiovascular and Metabolic Disease Center, Inje University, Busan, Korea
| | - Seung Hun Jeong
- National Research Laboratory for Mitochondrial Signaling, Department of Physiology, College of Medicine, Cardiovascular and Metabolic Disease Center, Inje University, Busan, Korea
| | - Hye Jin Heo
- National Research Laboratory for Mitochondrial Signaling, Department of Physiology, College of Medicine, Cardiovascular and Metabolic Disease Center, Inje University, Busan, Korea
| | - Hyoung Kyu Kim
- National Research Laboratory for Mitochondrial Signaling, Department of Physiology, College of Medicine, Cardiovascular and Metabolic Disease Center, Inje University, Busan, Korea
| | - Ki Beom Bae
- Department of Surgery, College of Medicine, Inje University, Busan Paik Hospital, Busan, Korea
| | - Young-Ho Park
- National Primate Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon, Korea
| | - Sun Uk Kim
- National Primate Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon, Korea
| | - Jin-Man Kim
- Department of Pathology, School of Medicine, Chungnam National University, Daejeon, Korea
| | - Nari Kim
- National Research Laboratory for Mitochondrial Signaling, Department of Physiology, College of Medicine, Cardiovascular and Metabolic Disease Center, Inje University, Busan, Korea
| | - Kyung Soo Ko
- National Research Laboratory for Mitochondrial Signaling, Department of Physiology, College of Medicine, Cardiovascular and Metabolic Disease Center, Inje University, Busan, Korea
| | - Byoung Doo Rhee
- National Research Laboratory for Mitochondrial Signaling, Department of Physiology, College of Medicine, Cardiovascular and Metabolic Disease Center, Inje University, Busan, Korea
| | - Jin Han
- National Research Laboratory for Mitochondrial Signaling, Department of Physiology, College of Medicine, Cardiovascular and Metabolic Disease Center, Inje University, Busan, Korea.
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130
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Abstract
In the past century, considerable efforts were made to understand the role of mitochondrial DNA (mtDNA) mutations and of oxidative stress in aging. The classic mitochondrial free radical theory of aging, in which mtDNA mutations cause genotoxic oxidative stress, which in turn creates more mutations, has been a central hypothesis in the field for decades. In the past few years, however, new elements have discredited this original theory. The major sources of mitochondrial DNA mutations seem to be replication errors and failure of the repair mechanisms, and the accumulation of these mutations as observed in aged organisms seems to occur by clonal expansion and not to be caused by a reactive oxygen species-dependent vicious cycle. New hypotheses of how age-associated mitochondrial dysfunction may lead to aging are based on the role of reactive oxygen species as signaling molecules and on their role in mediating stress responses to age-dependent damage. Here, we review the changes that mtDNA undergoes during aging and the past and most recent hypotheses linking these changes to the tissue failure observed in aging.
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Affiliation(s)
- Milena Pinto
- Department of Neurology, Miller School of Medicine, University of Miami, Miami, FL 33136, USA
| | - Carlos T Moraes
- Department of Neurology, Miller School of Medicine, University of Miami, Miami, FL 33136, USA; Department of Cell Biology and Anatomy, Miller School of Medicine, University of Miami, Miami, FL 33136, USA.
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131
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Orogo AM, Gonzalez ER, Kubli DA, Baptista IL, Ong SB, Prolla TA, Sussman MA, Murphy AN, Gustafsson ÅB. Accumulation of Mitochondrial DNA Mutations Disrupts Cardiac Progenitor Cell Function and Reduces Survival. J Biol Chem 2015; 290:22061-75. [PMID: 26183775 DOI: 10.1074/jbc.m115.649657] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Indexed: 11/06/2022] Open
Abstract
Transfer of cardiac progenitor cells (CPCs) improves cardiac function in heart failure patients. However, CPC function is reduced with age, limiting their regenerative potential. Aging is associated with numerous changes in cells including accumulation of mitochondrial DNA (mtDNA) mutations, but it is unknown how this impacts CPC function. Here, we demonstrate that acquisition of mtDNA mutations disrupts mitochondrial function, enhances mitophagy, and reduces the replicative and regenerative capacities of the CPCs. We show that activation of differentiation in CPCs is associated with expansion of the mitochondrial network and increased mitochondrial oxidative phosphorylation. Interestingly, mutant CPCs are deficient in mitochondrial respiration and rely on glycolysis for energy. In response to differentiation, these cells fail to activate mitochondrial respiration. This inability to meet the increased energy demand leads to activation of cell death. These findings demonstrate the consequences of accumulating mtDNA mutations and the importance of mtDNA integrity in CPC homeostasis and regenerative potential.
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Affiliation(s)
- Amabel M Orogo
- From the Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, California, 92093
| | - Eileen R Gonzalez
- From the Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, California, 92093
| | - Dieter A Kubli
- From the Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, California, 92093
| | - Igor L Baptista
- From the Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, California, 92093
| | - Sang-Bing Ong
- From the Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, California, 92093
| | - Tomas A Prolla
- Departments of Genetics and Medical Genetics, University of Wisconsin, Madison, Wisconsin 53706
| | - Mark A Sussman
- San Diego Heart Research Institute, San Diego State University, San Diego, California 92182, and
| | - Anne N Murphy
- Department of Pharmacology, University of California, San Diego, La Jolla, California 92093
| | - Åsa B Gustafsson
- From the Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, California, 92093, Department of Pharmacology, University of California, San Diego, La Jolla, California 92093,
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132
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High-fat diet and FGF21 cooperatively promote aerobic thermogenesis in mtDNA mutator mice. Proc Natl Acad Sci U S A 2015; 112:8714-9. [PMID: 26124126 DOI: 10.1073/pnas.1509930112] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Mitochondria are highly adaptable organelles that can facilitate communication between tissues to meet the energetic demands of the organism. However, the mechanisms by which mitochondria can nonautonomously relay stress signals remain poorly understood. Here we report that mitochondrial mutations in the young, preprogeroid polymerase gamma mutator (POLG) mouse produce a metabolic state of starvation. As a result, these mice exhibit signs of metabolic imbalance including thermogenic defects in brown adipose tissue (BAT). An unexpected benefit of this adaptive response is the complete resistance to diet-induced obesity when POLG mice are placed on a high-fat diet (HFD). Paradoxically, HFD further increases oxygen consumption in part by inducing thermogenesis and mitochondrial biogenesis in BAT along with enhanced expression of fibroblast growth factor 21 (FGF21). Collectively, these findings identify a mechanistic link between FGF21, a long-known marker of mitochondrial disease, and systemic metabolic adaptation in response to mitochondrial stress.
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133
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Koyuncu S, Irmak D, Saez I, Vilchez D. Defining the General Principles of Stem Cell Aging: Lessons from Organismal Models. CURRENT STEM CELL REPORTS 2015. [DOI: 10.1007/s40778-015-0017-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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134
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Tower J. Mitochondrial maintenance failure in aging and role of sexual dimorphism. Arch Biochem Biophys 2015; 576:17-31. [PMID: 25447815 PMCID: PMC4409928 DOI: 10.1016/j.abb.2014.10.008] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Revised: 10/08/2014] [Accepted: 10/18/2014] [Indexed: 12/31/2022]
Abstract
Gene expression changes during aging are partly conserved across species, and suggest that oxidative stress, inflammation and proteotoxicity result from mitochondrial malfunction and abnormal mitochondrial-nuclear signaling. Mitochondrial maintenance failure may result from trade-offs between mitochondrial turnover versus growth and reproduction, sexual antagonistic pleiotropy and genetic conflicts resulting from uni-parental mitochondrial transmission, as well as mitochondrial and nuclear mutations and loss of epigenetic regulation. Aging phenotypes and interventions are often sex-specific, indicating that both male and female sexual differentiation promote mitochondrial failure and aging. Studies in mammals and invertebrates implicate autophagy, apoptosis, AKT, PARP, p53 and FOXO in mediating sex-specific differences in stress resistance and aging. The data support a model where the genes Sxl in Drosophila, sdc-2 in Caenorhabditis elegans, and Xist in mammals regulate mitochondrial maintenance across generations and in aging. Several interventions that increase life span cause a mitochondrial unfolded protein response (UPRmt), and UPRmt is also observed during normal aging, indicating hormesis. The UPRmt may increase life span by stimulating mitochondrial turnover through autophagy, and/or by inhibiting the production of hormones and toxic metabolites. The data suggest that metazoan life span interventions may act through a common hormesis mechanism involving liver UPRmt, mitochondrial maintenance and sexual differentiation.
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Affiliation(s)
- John Tower
- Molecular and Computational Biology Program, Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089-2910, United States.
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135
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Payne BAI, Chinnery PF. Mitochondrial dysfunction in aging: Much progress but many unresolved questions. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2015; 1847:1347-53. [PMID: 26050973 PMCID: PMC4580208 DOI: 10.1016/j.bbabio.2015.05.022] [Citation(s) in RCA: 228] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/19/2015] [Revised: 05/21/2015] [Accepted: 05/26/2015] [Indexed: 12/31/2022]
Abstract
The free radical theory of aging is almost 60 years old. As mitochondria are the principle source of intracellular reactive oxygen species (ROS), this hypothesis suggested a central role for the mitochondrion in normal mammalian aging. In recent years, however, much work has questioned the importance of mitochondrial ROS in driving aging. Conversely new evidence points to other facets of mitochondrial dysfunction which may nevertheless suggest the mitochondrion retains a critical role at the center of a complex web of processes leading to cellular and organismal aging.
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Affiliation(s)
- Brendan A I Payne
- Wellcome Trust Centre for Mitochondrial Research, Institute of Genetic Medicine, Newcastle University, UK
| | - Patrick F Chinnery
- Wellcome Trust Centre for Mitochondrial Research, Institute of Genetic Medicine, Newcastle University, UK.
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136
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Mitochondrial DNA: Radically free of free-radical driven mutations. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2015; 1847:1354-61. [PMID: 26050972 DOI: 10.1016/j.bbabio.2015.06.001] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Revised: 05/08/2015] [Accepted: 06/02/2015] [Indexed: 01/31/2023]
Abstract
Mitochondrial DNA has long been posited as a likely target of oxidative damage induced mutation during the ageing process. Research over the past decades has uncovered the accumulation of mitochondrial DNA mutations in association with a mosaic pattern of cells displaying mitochondrial dysfunction in ageing individuals. Unfortunately, the underlying mechanisms are far less straightforward than originally anticipated. Recent research on mitochondria reveals that these genomes are far less helpless than originally envisioned. Additionally, new technologies have allowed us to analyze the mutational signatures of many more somatic mitochondrial DNA mutations, revealing surprising patterns that are inconsistent with a DNA-oxidative damage based hypothesis. In this review, we will discuss these recent observations and new insights into the eccentricities of mitochondrial genetics, and their impact on our understanding of mitochondrial mutations and their role in the ageing process. This article is part of a Special Issue entitled: Mitochondrial Dysfunction in Aging.
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137
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mtDNA Mutagenesis Disrupts Pluripotent Stem Cell Function by Altering Redox Signaling. Cell Rep 2015; 11:1614-24. [PMID: 26027936 PMCID: PMC4509707 DOI: 10.1016/j.celrep.2015.05.009] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Revised: 04/12/2015] [Accepted: 05/06/2015] [Indexed: 12/02/2022] Open
Abstract
mtDNA mutagenesis in somatic stem cells leads to their dysfunction and to progeria in mouse. The mechanism was proposed to involve modification of reactive oxygen species (ROS)/redox signaling. We studied the effect of mtDNA mutagenesis on reprogramming and stemness of pluripotent stem cells (PSCs) and show that PSCs select against specific mtDNA mutations, mimicking germline and promoting mtDNA integrity despite their glycolytic metabolism. Furthermore, mtDNA mutagenesis is associated with an increase in mitochondrial H2O2, reduced PSC reprogramming efficiency, and self-renewal. Mitochondria-targeted ubiquinone, MitoQ, and N-acetyl-L-cysteine efficiently rescued these defects, indicating that both reprogramming efficiency and stemness are modified by mitochondrial ROS. The redox sensitivity, however, rendered PSCs and especially neural stem cells sensitive to MitoQ toxicity. Our results imply that stem cell compartment warrants special attention when the safety of new antioxidants is assessed and point to an essential role for mitochondrial redox signaling in maintaining normal stem cell function. mtDNA mutagenesis affects reprogramming and stemness through redox signaling Altered redox signaling can be pharmacologically rescued by NAC or MitoQ Stem cells are sensitive to mitochondria-targeted ubiquinone toxicity Pluripotent stem cells show active selection against mtDNA mutations
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138
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Ahlqvist KJ, Suomalainen A, Hämäläinen RH. Stem cells, mitochondria and aging. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2015; 1847:1380-6. [PMID: 26014347 DOI: 10.1016/j.bbabio.2015.05.014] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Revised: 05/15/2015] [Accepted: 05/17/2015] [Indexed: 02/08/2023]
Abstract
Decline in metabolism and regenerative potential of tissues are common characteristics of aging. Regeneration is maintained by somatic stem cells (SSCs), which require tightly controlled energy metabolism and genomic integrity for their homeostasis. Recent data indicate that mitochondrial dysfunction may compromise this homeostasis, and thereby contribute to tissue degeneration and aging. Progeroid Mutator mouse, accumulating random mtDNA point mutations in their SSCs, showed disturbed SSC homeostasis, emphasizing the importance of mtDNA integrity for stem cells. The mechanism involved changes in cellular redox-environment, including subtle increase in reactive oxygen species (H₂O₂and superoxide anion), which did not cause oxidative damage, but disrupted SSC function. Mitochondrial metabolism appears therefore to be an important regulator of SSC fate determination, and defects in it in SSCs may underlie premature aging. Here we review the current knowledge of mitochondrial contribution to SSC dysfunction and aging. This article is part of a Special Issue entitled: Mitochondrial Dysfunction in Aging.
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Affiliation(s)
- Kati J Ahlqvist
- Research Programs Unit, Molecular Neurology, University of Helsinki, Helsinki, Finland
| | - Anu Suomalainen
- Research Programs Unit, Molecular Neurology, University of Helsinki, Helsinki, Finland; Helsinki University Central Hospital, Department of Neurology, Helsinki, Finland; Neuroscience Center, University of Helsinki, Helsinki, Finland.
| | - Riikka H Hämäläinen
- Research Programs Unit, Molecular Neurology, University of Helsinki, Helsinki, Finland
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139
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Abstract
The ketone body beta-hydroxybutyrate (βHB) is a histone deacetylase (HDAC) inhibitor and has been shown to be protective in many disease models, but its effects on aging are not well studied. Therefore we determined the effect of βHB supplementation on the lifespan of C. elegans nematodes. βHB supplementation extended mean lifespan by approximately 20%. RNAi knockdown of HDACs hda-2 or hda-3 also increased lifespan and further prevented βHB-mediated lifespan extension. βHB-mediated lifespan extension required the DAF-16/FOXO and SKN-1/Nrf longevity pathways, the sirtuin SIR-2.1, and the AMP kinase subunit AAK-2. βHB did not extend lifespan in a genetic model of dietary restriction indicating that βHB is likely functioning through a similar mechanism. βHB addition also upregulated βHB dehydrogenase activity and increased oxygen consumption in the worms. RNAi knockdown of F55E10.6, a short chain dehydrogenase and SKN-1 target gene, prevented the increased lifespan and βHB dehydrogenase activity induced by βHB addition, suggesting that F55E10.6 functions as an inducible βHB dehydrogenase. Furthermore, βHB supplementation increased worm thermotolerance and partially prevented glucose toxicity. It also delayed Alzheimer's amyloid-beta toxicity and decreased Parkinson's alpha-synuclein aggregation. The results indicate that D-βHB extends lifespan through inhibiting HDACs and through the activation of conserved stress response pathways.
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140
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141
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Mosaic Deficiency in Mitochondrial Oxidative Metabolism Promotes Cardiac Arrhythmia during Aging. Cell Metab 2015; 21:667-77. [PMID: 25955204 DOI: 10.1016/j.cmet.2015.04.005] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/27/2014] [Revised: 02/04/2015] [Accepted: 03/31/2015] [Indexed: 11/21/2022]
Abstract
Aging is a progressive decline of body function, during which many tissues accumulate few cells with high levels of deleted mitochondrial DNA (mtDNA), leading to a defect of mitochondrial functions. Whether this mosaic mitochondrial deficiency contributes to organ dysfunction is unknown. To investigate this, we generated mice with an accelerated accumulation of mtDNA deletions in the myocardium, by expressing a dominant-negative mutant mitochondrial helicase. These animals accumulated few randomly distributed cardiomyocytes with compromised mitochondrial function, which led to spontaneous ventricular premature contractions and AV blocks at 18 months. These symptoms were not caused by a general mitochondrial dysfunction in the entire myocardium, and were not observed in mice at 12 months with significantly lower numbers of dysfunctional cells. Therefore, our results suggest that the disposition to arrhythmia typically found in the aged human heart might be due to the random accumulation of mtDNA deletions and the subsequent mosaic respiratory chain deficiency.
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142
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Shabalina IG, Landreh L, Edgar D, Hou M, Gibanova N, Atanassova N, Petrovic N, Hultenby K, Söder O, Nedergaard J, Svechnikov K. Leydig cell steroidogenesis unexpectedly escapes mitochondrial dysfunction in prematurely aging mice. FASEB J 2015; 29:3274-86. [PMID: 25900807 DOI: 10.1096/fj.15-271825] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Accepted: 03/31/2015] [Indexed: 11/11/2022]
Abstract
Point mutations and deletions of mitochondrial DNA (mtDNA) accumulate in tissues during aging in animals and humans and are the basis for mitochondrial diseases. Testosterone synthesis occurs in the mitochondria of Leydig cells. Mitochondrial dysfunction (as induced here experimentally in mtDNA mutator mice that carry a proofreading-deficient form of mtDNA polymerase γ, leading to mitochondrial dysfunction in all cells types so far studied) would therefore be expected to lead to low testosterone levels. Although mtDNA mutator mice showed a dramatic reduction in testicle weight (only 15% remaining) and similar decreases in number of spermatozoa, testosterone levels in mtDNA mutator mice were unexpectedly fully unchanged. Leydig cell did not escape mitochondrial damage (only 20% of complex I and complex IV remaining) and did show high levels of reactive oxygen species (ROS) production (>5-fold increased), and permeabilized cells demonstrated absence of normal mitochondrial function. Nevertheless, within intact cells, mitochondrial membrane potential remained high, and testosterone production was maintained. This implies development of a compensatory mechanism. A rescuing mechanism involving electrons from the pentose phosphate pathway transferred via a 3-fold up-regulated cytochrome b5 to cytochrome c, allowing for mitochondrial energization, is suggested. Thus, the Leydig cells escape mitochondrial dysfunction via a unique rescue pathway. Such a pathway, bypassing respiratory chain dysfunction, may be of relevance with regard to mitochondrial disease therapy and to managing ageing in general.
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Affiliation(s)
- Irina G Shabalina
- *Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden; Department of Women's and Children's Health, Pediatric Endocrinology Unit, Astrid Lindgren's Children Hospital, Stockholm, Sweden; Department of Laboratory Medicine, Karolinska Institutet, Huddinge, Sweden; and Institute of Experimental Morphology, Pathology and Anthropology with Museum, Sofia, Bulgaria
| | - Luise Landreh
- *Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden; Department of Women's and Children's Health, Pediatric Endocrinology Unit, Astrid Lindgren's Children Hospital, Stockholm, Sweden; Department of Laboratory Medicine, Karolinska Institutet, Huddinge, Sweden; and Institute of Experimental Morphology, Pathology and Anthropology with Museum, Sofia, Bulgaria
| | - Daniel Edgar
- *Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden; Department of Women's and Children's Health, Pediatric Endocrinology Unit, Astrid Lindgren's Children Hospital, Stockholm, Sweden; Department of Laboratory Medicine, Karolinska Institutet, Huddinge, Sweden; and Institute of Experimental Morphology, Pathology and Anthropology with Museum, Sofia, Bulgaria
| | - Mi Hou
- *Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden; Department of Women's and Children's Health, Pediatric Endocrinology Unit, Astrid Lindgren's Children Hospital, Stockholm, Sweden; Department of Laboratory Medicine, Karolinska Institutet, Huddinge, Sweden; and Institute of Experimental Morphology, Pathology and Anthropology with Museum, Sofia, Bulgaria
| | - Natalia Gibanova
- *Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden; Department of Women's and Children's Health, Pediatric Endocrinology Unit, Astrid Lindgren's Children Hospital, Stockholm, Sweden; Department of Laboratory Medicine, Karolinska Institutet, Huddinge, Sweden; and Institute of Experimental Morphology, Pathology and Anthropology with Museum, Sofia, Bulgaria
| | - Nina Atanassova
- *Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden; Department of Women's and Children's Health, Pediatric Endocrinology Unit, Astrid Lindgren's Children Hospital, Stockholm, Sweden; Department of Laboratory Medicine, Karolinska Institutet, Huddinge, Sweden; and Institute of Experimental Morphology, Pathology and Anthropology with Museum, Sofia, Bulgaria
| | - Natasa Petrovic
- *Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden; Department of Women's and Children's Health, Pediatric Endocrinology Unit, Astrid Lindgren's Children Hospital, Stockholm, Sweden; Department of Laboratory Medicine, Karolinska Institutet, Huddinge, Sweden; and Institute of Experimental Morphology, Pathology and Anthropology with Museum, Sofia, Bulgaria
| | - Kjell Hultenby
- *Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden; Department of Women's and Children's Health, Pediatric Endocrinology Unit, Astrid Lindgren's Children Hospital, Stockholm, Sweden; Department of Laboratory Medicine, Karolinska Institutet, Huddinge, Sweden; and Institute of Experimental Morphology, Pathology and Anthropology with Museum, Sofia, Bulgaria
| | - Olle Söder
- *Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden; Department of Women's and Children's Health, Pediatric Endocrinology Unit, Astrid Lindgren's Children Hospital, Stockholm, Sweden; Department of Laboratory Medicine, Karolinska Institutet, Huddinge, Sweden; and Institute of Experimental Morphology, Pathology and Anthropology with Museum, Sofia, Bulgaria
| | - Jan Nedergaard
- *Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden; Department of Women's and Children's Health, Pediatric Endocrinology Unit, Astrid Lindgren's Children Hospital, Stockholm, Sweden; Department of Laboratory Medicine, Karolinska Institutet, Huddinge, Sweden; and Institute of Experimental Morphology, Pathology and Anthropology with Museum, Sofia, Bulgaria
| | - Konstantin Svechnikov
- *Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden; Department of Women's and Children's Health, Pediatric Endocrinology Unit, Astrid Lindgren's Children Hospital, Stockholm, Sweden; Department of Laboratory Medicine, Karolinska Institutet, Huddinge, Sweden; and Institute of Experimental Morphology, Pathology and Anthropology with Museum, Sofia, Bulgaria
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143
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Abstract
Because of their high-energy metabolism, neurons are strictly dependent on mitochondria, which generate cellular ATP through oxidative phosphorylation. The mitochondrial genome encodes for critical components of the oxidative phosphorylation pathway machinery, and therefore, mutations in mitochondrial DNA (mtDNA) cause energy production defects that frequently have severe neurological manifestations. Here, we review the principles of mitochondrial genetics and focus on prototypical mitochondrial diseases to illustrate how primary defects in mtDNA or secondary defects in mtDNA due to nuclear genome mutations can cause prominent neurological and multisystem features. In addition, we discuss the pathophysiological mechanisms underlying mitochondrial diseases, the cellular mechanisms that protect mitochondrial integrity, and the prospects for therapy.
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Affiliation(s)
- Valerio Carelli
- IRCCS Institute of Neurological Sciences of Bologna, Bellaria Hospital, Bologna, Italy; Neurology Unit, Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, Italy
| | - David C Chan
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA.
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144
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How do changes in the mtDNA and mitochondrial dysfunction influence cancer and cancer therapy? Challenges, opportunities and models. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2015; 764:16-30. [DOI: 10.1016/j.mrrev.2015.01.001] [Citation(s) in RCA: 137] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Revised: 01/11/2015] [Accepted: 01/12/2015] [Indexed: 12/28/2022]
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145
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MtDNA mutagenesis impairs elimination of mitochondria during erythroid maturation leading to enhanced erythrocyte destruction. Nat Commun 2015; 6:6494. [PMID: 25751021 DOI: 10.1038/ncomms7494] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Accepted: 02/03/2015] [Indexed: 12/22/2022] Open
Abstract
Haematopoietic progenitor cells show special sensitivity to mitochondrial DNA (mtDNA) mutagenesis, which suggests that increased mtDNA mutagenesis could underlie anemias. Here we show that elevated mtDNA mutagenesis in mice with a proof-reading deficient mtDNA polymerase (PolG) leads to incomplete mitochondrial clearance, with asynchronized iron loading in erythroid precursors, and increased total and free cellular iron content. The resulting Fenton chemistry leads to oxidative damage and premature destruction of erythrocytes by splenic macrophages. Our data indicate that mitochondria actively contribute to their own elimination in reticulocytes and modulate iron loading. Asynchrony of this sequence of events causes severe mitochondrial anaemia by depleting the organism of red blood cells and the bone marrow of iron. Our findings account for the anaemia development in a progeroid mouse model and may have direct relevance to the anemias associated with human mitochondrial disease and ageing.
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146
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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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147
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Peralta S, Torraco A, Iommarini L, Diaz F. Mitochondrial Diseases Part III: Therapeutic interventions in mouse models of OXPHOS deficiencies. Mitochondrion 2015; 23:71-80. [PMID: 25638392 DOI: 10.1016/j.mito.2015.01.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Accepted: 01/22/2015] [Indexed: 12/19/2022]
Abstract
Mitochondrial defects are the cause of numerous disorders affecting the oxidative phosphorylation system (OXPHOS) in humans leading predominantly to neurological and muscular degeneration. The molecular origin, manifestations, and progression of mitochondrial diseases have a broad spectrum, which makes very challenging to find a globally effective therapy. The study of the molecular mechanisms underlying the mitochondrial dysfunction indicates that there is a wide range of pathways, enzymes and molecules that can be potentially targeted for therapeutic purposes. Therefore, focusing on the pathology of the disease is essential to design new treatments. In this review, we will summarize and discuss the different therapeutic interventions tested in some mouse models of mitochondrial diseases emphasizing the molecular mechanisms of action and their potential applications.
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Affiliation(s)
- Susana Peralta
- Department of Neurology, University of Miami, Miller School of Medicine, Miami, FL 33136, USA.
| | - Alessandra Torraco
- Neuromuscular and Neurodegenerative Disorders, Laboratory of Molecular Medicine, Bambino Gesù Children's Hospital, IRCCS, Viale di San Paolo, 15 - 00146, Rome, Italy.
| | - Luisa Iommarini
- Department of Pharmacy and Biotechnology (FABIT), University of Bologna, Via Irnerio 42, 40126, Bologna, Italy.
| | - Francisca Diaz
- Department of Neurology, University of Miami, Miller School of Medicine, Miami, FL 33136, USA.
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148
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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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149
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Abstract
Oxidative stress refers to elevated intracellular levels of reactive oxygen species (ROS) that cause damage to lipids, proteins and DNA. Oxidative stress has been linked to a myriad of pathologies. However, elevated ROS also act as signaling molecules in the maintenance of physiological functions--a process termed redox biology. In this review we discuss the two faces of ROS--redox biology and oxidative stress--and their contribution to both physiological and pathological conditions. Redox biology involves a small increase in ROS levels that activates signaling pathways to initiate biological processes, while oxidative stress denotes high levels of ROS that result in damage to DNA, protein or lipids. Thus, the response to ROS displays hormesis, given that the opposite effect is observed at low levels compared with that seen at high levels. Here, we argue that redox biology, rather than oxidative stress, underlies physiological and pathological conditions.
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Affiliation(s)
- Michael Schieber
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, The Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Navdeep S Chandel
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, The Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA.
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150
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Martin L, Gardner LB. Stress-induced inhibition of nonsense-mediated RNA decay regulates intracellular cystine transport and intracellular glutathione through regulation of the cystine/glutamate exchanger SLC7A11. Oncogene 2014; 34:4211-8. [PMID: 25399695 PMCID: PMC4433865 DOI: 10.1038/onc.2014.352] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Revised: 08/18/2014] [Accepted: 09/11/2014] [Indexed: 12/18/2022]
Abstract
SLC7A11 encodes a subunit of the xCT cystine/glutamate amino acid transport system and plays a critical role in the generation of glutathione and the protection of cells from oxidative stress. Expression of SLC7A11 promotes tumorigenesis and chemotherapy resistance, but while SLC7A11 has been previously noted to be upregulated in hypoxic cells its regulation has not been fully delineated. We have recently shown that nonsense mediated RNA decay (NMD) is inhibited by cellular stresses generated by the tumor microenvironment, including hypoxia, and augments tumorigenesis. Here we demonstrate that the inhibition of NMD by various cellular stresses leads to the stabilization and upregulation of SLC7A11 mRNA and protein. The inhibition of NMD and upregulation of SLC7A11 augments intracellular cystine transport, and increases intracellular levels of cysteine and glutathione. Accordinglyy, the inhibition of NMD protects cells against oxidative stress via SLC7A11 upregulation. Together our studies identify a mechanism for the dynamic regulation of SLC7A11, through the stress-inhibited regulation of NMD, and add to the growing evidence that the inhibition of NMD is an adaptive response.
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Affiliation(s)
- L Martin
- Department of Medicine, New York University School of Medicine, New York, NY, USA
| | - L B Gardner
- 1] Department of Medicine, New York University School of Medicine, New York, NY, USA [2] Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY, USA [3] NYU Perlmutter Cancer Center, New York University School of Medicine, New York, NY, USA
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