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Villanueva Paz M, Cotán D, Garrido-Maraver J, Cordero MD, Oropesa-Ávila M, de La Mata M, Delgado Pavón A, de Lavera I, Alcocer-Gómez E, Sánchez-Alcázar JA. Targeting autophagy and mitophagy for mitochondrial diseases treatment. Expert Opin Ther Targets 2015; 20:487-500. [PMID: 26523761 DOI: 10.1517/14728222.2016.1101068] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
INTRODUCTION Mitochondrial diseases are a group of rare genetic diseases with complex and heterogeneous origins which manifest a great variety of phenotypes. Disruption of the oxidative phosphorylation system is the main cause of pathogenicity in mitochondrial diseases since it causes accumulation of reactive oxygen species (ROS) and ATP depletion. AREAS COVERED Current evidences support the main protective role of autophagy and mitophagy in mitochondrial diseases and other diseases associated with mitochondrial dysfunction. EXPERT OPINION The use of autophagy and/or mitophagy inducers may allow a novel strategy for improving mitochondrial function for both mitochondrial diseases and other diseases with altered mitochondrial metabolism. However, a deeper investigation of the molecular mechanisms behind mitophagy and mitochondrial biogenesis is needed in order to safely modulate these processes. In the coming years, we will also see an increase in awareness of mitochondrial dynamics modulation that will allow the therapeutic use of new drugs for improving mitochondrial function in a great variety of mitochondrial disorders.
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Affiliation(s)
- Marina Villanueva Paz
- a Centro Andaluz de Biología del Desarrollo (CABD), and Centro de Investigación Biomédica en Red: Enfermedades Raras, Instituto de Salud Carlos III , Universidad Pablo de Olavide-Consejo Superior de Investigaciones Científicas , Carretera de Utrera Km 1, Sevilla 41013 , Spain
| | - David Cotán
- a Centro Andaluz de Biología del Desarrollo (CABD), and Centro de Investigación Biomédica en Red: Enfermedades Raras, Instituto de Salud Carlos III , Universidad Pablo de Olavide-Consejo Superior de Investigaciones Científicas , Carretera de Utrera Km 1, Sevilla 41013 , Spain
| | - Juan Garrido-Maraver
- a Centro Andaluz de Biología del Desarrollo (CABD), and Centro de Investigación Biomédica en Red: Enfermedades Raras, Instituto de Salud Carlos III , Universidad Pablo de Olavide-Consejo Superior de Investigaciones Científicas , Carretera de Utrera Km 1, Sevilla 41013 , Spain
| | - Mario D Cordero
- b Facultad de Odontología , Universidad de Sevilla , Sevilla 41009 , Spain
| | - Manuel Oropesa-Ávila
- a Centro Andaluz de Biología del Desarrollo (CABD), and Centro de Investigación Biomédica en Red: Enfermedades Raras, Instituto de Salud Carlos III , Universidad Pablo de Olavide-Consejo Superior de Investigaciones Científicas , Carretera de Utrera Km 1, Sevilla 41013 , Spain
| | - Mario de La Mata
- a Centro Andaluz de Biología del Desarrollo (CABD), and Centro de Investigación Biomédica en Red: Enfermedades Raras, Instituto de Salud Carlos III , Universidad Pablo de Olavide-Consejo Superior de Investigaciones Científicas , Carretera de Utrera Km 1, Sevilla 41013 , Spain
| | - Ana Delgado Pavón
- a Centro Andaluz de Biología del Desarrollo (CABD), and Centro de Investigación Biomédica en Red: Enfermedades Raras, Instituto de Salud Carlos III , Universidad Pablo de Olavide-Consejo Superior de Investigaciones Científicas , Carretera de Utrera Km 1, Sevilla 41013 , Spain
| | - Isabel de Lavera
- a Centro Andaluz de Biología del Desarrollo (CABD), and Centro de Investigación Biomédica en Red: Enfermedades Raras, Instituto de Salud Carlos III , Universidad Pablo de Olavide-Consejo Superior de Investigaciones Científicas , Carretera de Utrera Km 1, Sevilla 41013 , Spain
| | - Elizabet Alcocer-Gómez
- a Centro Andaluz de Biología del Desarrollo (CABD), and Centro de Investigación Biomédica en Red: Enfermedades Raras, Instituto de Salud Carlos III , Universidad Pablo de Olavide-Consejo Superior de Investigaciones Científicas , Carretera de Utrera Km 1, Sevilla 41013 , Spain
| | - José A Sánchez-Alcázar
- a Centro Andaluz de Biología del Desarrollo (CABD), and Centro de Investigación Biomédica en Red: Enfermedades Raras, Instituto de Salud Carlos III , Universidad Pablo de Olavide-Consejo Superior de Investigaciones Científicas , Carretera de Utrera Km 1, Sevilla 41013 , Spain
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Williams JA, Ding WX. A Mechanistic Review of Mitophagy and Its Role in Protection against Alcoholic Liver Disease. Biomolecules 2015; 5:2619-42. [PMID: 26501336 PMCID: PMC4693250 DOI: 10.3390/biom5042619] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2015] [Revised: 09/23/2015] [Accepted: 09/25/2015] [Indexed: 12/15/2022] Open
Abstract
Alcoholic liver disease (ALD) is a major health problem worldwide, and alcohol is well-known to cause mitochondrial damage, which exacerbates alcohol-induced liver injury and steatosis. No successful treatments are currently available for treating ALD. Therefore, a better understanding of mechanisms involved in regulation of mitochondrial homeostasis in the liver and how these mechanisms may protect against alcohol-induced liver disease is needed for future development of better therapeutic options for ALD. Mitophagy is a key mechanism for maintaining mitochondrial homeostasis by removing damaged mitochondria, and mitophagy protects against alcohol-induced liver injury. Parkin, an E3 ubiquitin ligase, is well-known to induce mitophagy in in vitro models although Parkin-independent mechanisms for mitophagy induction also exist. In this review, we discuss the roles of Parkin and mitophagy in protection against alcohol-induced liver injury and steatosis. We also discuss Parkin-independent mechanisms for mitophagy induction, which have not yet been evaluated in the liver but may also potentially have a protective role against ALD. In addition to mitophagy, mitochondrial spheroid formation may also provide a novel mechanism of protection against ALD, but the role of mitochondrial spheroids in protection against ALD progression needs to be further explored. Targeting removal of damaged mitochondria by mitophagy or inducing formation of mitochondrial spheroids may be promising therapeutic options for treatment of ALD.
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Affiliation(s)
- Jessica A Williams
- Department of Pharmacology, Toxicology and Therapeutics, University of Kansas Medical Center, 3901 Rainbow Blvd., Kansas City, KS 66160, USA.
| | - Wen-Xing Ding
- Department of Pharmacology, Toxicology and Therapeutics, University of Kansas Medical Center, 3901 Rainbow Blvd., Kansas City, KS 66160, USA.
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53
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Tranah GJ, Yaffe K, Katzman SM, Lam ET, Pawlikowska L, Kwok PY, Schork NJ, Manini TM, Kritchevsky S, Thomas F, Newman AB, Harris TB, Coleman AL, Gorin MB, Helzner EP, Rowbotham MC, Browner WS, Cummings SR. Mitochondrial DNA Heteroplasmy Associations With Neurosensory and Mobility Function in Elderly Adults. J Gerontol A Biol Sci Med Sci 2015; 70:1418-24. [PMID: 26328603 DOI: 10.1093/gerona/glv097] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Accepted: 06/05/2015] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Mitochondrial DNA (mtDNA) heteroplasmy is a mixture of normal and mutated mtDNA molecules in a cell. High levels of heteroplasmy at specific mtDNA sites lead to inherited mitochondrial diseases with neurological, sensory, and movement impairments. Here we test the hypothesis that heteroplasmy levels in elderly adults are associated with impaired function resembling mild forms of mitochondrial disease. METHODS We examined platelet mtDNA heteroplasmy at 20 disease-causing sites for associations with neurosensory and mobility function among 137 participants from the community-based Health, Aging, and Body Composition Study. RESULTS Elevated mtDNA heteroplasmy at four mtDNA sites in complex I and tRNA genes was nominally associated with reduced cognition, vision, hearing, and mobility: m.10158T>C with Modified Mini-Mental State Examination score (p = .009); m.11778G>A with contrast sensitivity (p = .02); m.7445A>G with high-frequency hearing (p = .047); and m.5703G>A with 400 m walking speed (p = .007). CONCLUSIONS These results indicate that increased mtDNA heteroplasmy at disease-causing sites is associated with neurosensory and mobility function in older persons. We propose the novel use of mtDNA heteroplasmy as a simple, noninvasive predictor of age-related neurologic, sensory, and movement impairments.
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Affiliation(s)
- Gregory J Tranah
- California Pacific Medical Center Research Institute, San Francisco.
| | - Kristine Yaffe
- Department of Psychiatry, Department of Neurology and Department of Epidemiology, University of California San Francisco and the San Francisco VA Medical Center
| | | | | | - Ludmila Pawlikowska
- Department of Anesthesia and Perioperative Care, University of California San Francisco. Institute for Human Genetics, University of California San Francisco
| | - Pui-Yan Kwok
- Institute for Human Genetics, University of California San Francisco
| | - Nicholas J Schork
- J. Craig Venter Institute and the University of California, San Diego
| | - Todd M Manini
- Department of Aging and Geriatric Research, University of Florida, Gainesville
| | - Stephen Kritchevsky
- Sticht Center on Aging, Wake Forest School of Medicine, Winston-Salem, North Carolina
| | - Fridtjof Thomas
- Department of Preventive Medicine, The University of Tennessee Health Science Center, Memphis
| | - Anne B Newman
- Department of Epidemiology, University of Pittsburgh, Pennsylvania
| | - Tamara B Harris
- Intramural Research Program, Laboratory of Epidemiology and Population Sciences, National Institute on Aging, Bethesda, Maryland
| | - Anne L Coleman
- Jules Stein Eye Institute and UCLA Department of Ophthalmology, Los Angeles, California
| | - Michael B Gorin
- Jules Stein Eye Institute and UCLA Department of Ophthalmology, Los Angeles, California
| | - Elizabeth P Helzner
- Department of Epidemiology and Biostatistics, SUNY Downstate Medical Center, Brooklyn, New York
| | | | - Warren S Browner
- California Pacific Medical Center Research Institute, San Francisco
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Diot A, Hinks-Roberts A, Lodge T, Liao C, Dombi E, Morten K, Brady S, Fratter C, Carver J, Muir R, Davis R, Green CJ, Johnston I, Hilton-Jones D, Sue C, Mortiboys H, Poulton J. A novel quantitative assay of mitophagy: Combining high content fluorescence microscopy and mitochondrial DNA load to quantify mitophagy and identify novel pharmacological tools against pathogenic heteroplasmic mtDNA. Pharmacol Res 2015. [PMID: 26196248 DOI: 10.1016/j.phrs.2015.07.014] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Mitophagy is a cellular mechanism for the recycling of mitochondrial fragments. This process is able to improve mitochondrial DNA (mtDNA) quality in heteroplasmic mtDNA disease, in which mutant mtDNA co-exists with normal mtDNA. In disorders where the load of mutant mtDNA determines disease severity it is likely to be an important determinant of disease progression. Measuring mitophagy is technically demanding. We used pharmacological modulators of autophagy to validate two techniques for quantifying mitophagy. First we used the IN Cell 1000 analyzer to quantify mitochondrial co-localisation with LC3-II positive autophagosomes. Unlike conventional fluorescence and electron microscopy, this high-throughput system is sufficiently sensitive to detect transient low frequency autophagosomes. Secondly, because mitophagy preferentially removes pathogenic heteroplasmic mtDNA mutants, we developed a heteroplasmy assay based on loss of m.3243A>G mtDNA, during culture conditions requiring oxidative metabolism ("energetic stress"). The effects of the pharmacological modulators on these two measures were consistent, confirming that the high throughput imaging output (autophagosomes co-localising with mitochondria) reflects mitochondrial quality control. To further validate these methods, we performed a more detailed study using metformin, the most commonly prescribed antidiabetic drug that is still sometimes used in Maternally Inherited Diabetes and Deafness (MIDD). This confirmed our initial findings and revealed that metformin inhibits mitophagy at clinically relevant concentrations, suggesting that it may have novel therapeutic uses.
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Affiliation(s)
- Alan Diot
- Nuffield Department of Obstetrics and Gynaecology, Women's Centre, Oxford, UK
| | - Alex Hinks-Roberts
- Nuffield Department of Obstetrics and Gynaecology, Women's Centre, Oxford, UK
| | - Tiffany Lodge
- Nuffield Department of Obstetrics and Gynaecology, Women's Centre, Oxford, UK
| | - Chunyan Liao
- Nuffield Department of Obstetrics and Gynaecology, Women's Centre, Oxford, UK
| | - Eszter Dombi
- Nuffield Department of Obstetrics and Gynaecology, Women's Centre, Oxford, UK
| | - Karl Morten
- Nuffield Department of Obstetrics and Gynaecology, Women's Centre, Oxford, UK
| | - Stefen Brady
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - Carl Fratter
- Oxford Medical Genetics Laboratory, Oxford University Hospitals NHS Trust, Churchill Hospital, Oxford, UK
| | - Janet Carver
- Nuffield Department of Obstetrics and Gynaecology, Women's Centre, Oxford, UK
| | - Rebecca Muir
- Nuffield Department of Obstetrics and Gynaecology, Women's Centre, Oxford, UK
| | - Ryan Davis
- Department of Neurogenetics, Kolling Institute of Medical Research, University of Sydney and Royal North Shore Hospital, Sydney, Australia
| | - Charlotte J Green
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford, UK
| | - Iain Johnston
- Department of Mathematics, Imperial College London, London, UK
| | | | - Carolyn Sue
- Department of Neurogenetics, Kolling Institute of Medical Research, University of Sydney and Royal North Shore Hospital, Sydney, Australia
| | - Heather Mortiboys
- Department of Neuroscience, Sheffield Institute of Translational Neuroscience, University of Sheffield, Sheffield, UK
| | - Joanna Poulton
- Nuffield Department of Obstetrics and Gynaecology, Women's Centre, Oxford, UK.
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Ruetenik A, Barrientos A. Dietary restriction, mitochondrial function and aging: from yeast to humans. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2015; 1847:1434-47. [PMID: 25979234 DOI: 10.1016/j.bbabio.2015.05.005] [Citation(s) in RCA: 88] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2015] [Revised: 04/30/2015] [Accepted: 05/05/2015] [Indexed: 12/20/2022]
Abstract
Dietary restriction (DR) attenuates many detrimental effects of aging and consequently promotes health and increases longevity across organisms. While over the last 15 years extensive research has been devoted towards understanding the biology of aging, the precise mechanistic aspects of DR are yet to be settled. Abundant experimental evidence indicates that the DR effect on stimulating health impinges several metabolic and stress-resistance pathways. Downstream effects of these pathways include a reduction in cellular damage induced by oxidative stress, enhanced efficiency of mitochondrial functions and maintenance of mitochondrial dynamics and quality control, thereby attenuating age-related declines in mitochondrial function. However, the literature also accumulates conflicting evidence regarding how DR ameliorates mitochondrial performance and whether that is enough to slow age-dependent cellular and organismal deterioration. Here, we will summarize the current knowledge about how and to which extent the influence of different DR regimes on mitochondrial biogenesis and function contribute to postpone the detrimental effects of aging on health-span and lifespan. This article is part of a Special Issue entitled: Mitochondrial Dysfunction in Aging.
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Affiliation(s)
| | - Antoni Barrientos
- Neuroscience Graduate Program; Department of Neurology, University of Miami Miller School of Medicine, Miami, FL 33136, USA.
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56
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Hofmann JW, Zhao X, De Cecco M, Peterson AL, Pagliaroli L, Manivannan J, Hubbard GB, Ikeno Y, Zhang Y, Feng B, Li X, Serre T, Qi W, Van Remmen H, Miller RA, Bath KG, de Cabo R, Xu H, Neretti N, Sedivy JM. Reduced expression of MYC increases longevity and enhances healthspan. Cell 2015; 160:477-88. [PMID: 25619689 DOI: 10.1016/j.cell.2014.12.016] [Citation(s) in RCA: 201] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2014] [Revised: 10/21/2014] [Accepted: 12/03/2014] [Indexed: 01/18/2023]
Abstract
MYC is a highly pleiotropic transcription factor whose deregulation promotes cancer. In contrast, we find that Myc haploinsufficient (Myc(+/-)) mice exhibit increased lifespan. They show resistance to several age-associated pathologies, including osteoporosis, cardiac fibrosis, and immunosenescence. They also appear to be more active, with a higher metabolic rate and healthier lipid metabolism. Transcriptomic analysis reveals a gene expression signature enriched for metabolic and immune processes. The ancestral role of MYC as a regulator of ribosome biogenesis is reflected in reduced protein translation, which is inversely correlated with longevity. We also observe changes in nutrient and energy sensing pathways, including reduced serum IGF-1, increased AMPK activity, and decreased AKT, TOR, and S6K activities. In contrast to observations in other longevity models, Myc(+/-) mice do not show improvements in stress management pathways. Our findings indicate that MYC activity has a significant impact on longevity and multiple aspects of mammalian healthspan.
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Affiliation(s)
- Jeffrey W Hofmann
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, RI 02912, USA
| | - Xiaoai Zhao
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, RI 02912, USA
| | - Marco De Cecco
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, RI 02912, USA
| | - Abigail L Peterson
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, RI 02912, USA
| | - Luca Pagliaroli
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, RI 02912, USA
| | - Jayameenakshi Manivannan
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, RI 02912, USA
| | - Gene B Hubbard
- Department of Cellular and Structural Biology, Barshop Institute for Longevity and Aging Studies, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - Yuji Ikeno
- Department of Cellular and Structural Biology, Barshop Institute for Longevity and Aging Studies, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - Yongqing Zhang
- Translational Gerontology Branch, National Institute on Aging, 251 Bayview Boulevard, Suite 100, Baltimore, MD 21224, USA
| | - Bin Feng
- Hallett Center for Diabetes and Endocrinology, Rhode Island Hospital, Warren Alpert Medical School of Brown University, Providence, RI 02903, USA
| | - Xiaxi Li
- Department of Cognitive, Linguistic, and Psychological Sciences, Brown University, Providence, RI 02912, USA
| | - Thomas Serre
- Department of Cognitive, Linguistic, and Psychological Sciences, Brown University, Providence, RI 02912, USA
| | - Wenbo Qi
- Department of Cellular and Structural Biology, Barshop Institute for Longevity and Aging Studies, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - Holly Van Remmen
- Department of Cellular and Structural Biology, Barshop Institute for Longevity and Aging Studies, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - Richard A Miller
- Department of Pathology and Geriatrics Center, University of Michigan, Ann Arbor, MI 48109, USA
| | - Kevin G Bath
- Department of Cognitive, Linguistic, and Psychological Sciences, Brown University, Providence, RI 02912, USA
| | - Rafael de Cabo
- Translational Gerontology Branch, National Institute on Aging, 251 Bayview Boulevard, Suite 100, Baltimore, MD 21224, USA
| | - Haiyan Xu
- Hallett Center for Diabetes and Endocrinology, Rhode Island Hospital, Warren Alpert Medical School of Brown University, Providence, RI 02903, USA
| | - Nicola Neretti
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, RI 02912, USA
| | - John M Sedivy
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, RI 02912, USA.
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Holt IJ, Speijer D, Kirkwood TBL. The road to rack and ruin: selecting deleterious mitochondrial DNA variants. Philos Trans R Soc Lond B Biol Sci 2015; 369:20130451. [PMID: 24864317 DOI: 10.1098/rstb.2013.0451] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Mitochondria constitute the major energy-producing compartment of the eukaryotic cell. These organelles contain many molecules of DNA that contribute only a handful of proteins required for energy production. Mutations in the DNA of mitochondria were identified as a cause of human disease a quarter of a century ago, and they have subsequently been implicated in ageing. The process whereby deleterious variants come to dominate a cell, tissue or human is the subject of debate. It is likely to involve multiple, often competing, factors, as selection pressures on mitochondrial DNA can be both indirect and intermittent, and are subjected to rapid change. Here, we assess the different models and the prospects for preventing the accumulation of deleterious mitochondrial DNA variants with time.
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Affiliation(s)
- Ian J Holt
- MRC National Institute for Medical Research, Mill Hill, London NW7 1AA, UK
| | - Dave Speijer
- Department of Medical Biochemistry, Academic Medical Centre, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands
| | - Thomas B L Kirkwood
- Institute for Ageing and Health, Newcastle University, Campus for Ageing and Vitality, Newcastle upon Tyne NE4 5PL, UK
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Busch KB, Kowald A, Spelbrink JN. Quality matters: how does mitochondrial network dynamics and quality control impact on mtDNA integrity? Philos Trans R Soc Lond B Biol Sci 2015; 369:20130442. [PMID: 24864312 DOI: 10.1098/rstb.2013.0442] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Mammalian mtDNA encodes for 13 core proteins of oxidative phosphorylation. Mitochondrial DNA mutations and deletions cause severe myopathies and neuromuscular diseases. Thus, the integrity of mtDNA is pivotal for cell survival and health of the organism. We here discuss the possible impact of mitochondrial fusion and fission on mtDNA maintenance as well as positive and negative selection processes. Our focus is centred on the important question of how the quality of mtDNA nucleoids can be assured when selection and mitochondrial quality control works on functional and physiological phenotypes constituted by oxidative phosphorylation proteins. The organelle control theory suggests a link between phenotype and nucleoid genotype. This is discussed in the light of new results presented here showing that mitochondrial transcription factor A/nucleoids are restricted in their intramitochondrial mobility and probably have a limited sphere of influence. Together with recent published work on mitochondrial and mtDNA heteroplasmy dynamics, these data suggest first, that single mitochondria might well be internally heterogeneous and second, that nucleoid genotypes might be linked to local phenotypes (although the link might often be leaky). We discuss how random or site-specific mitochondrial fission can isolate dysfunctional parts and enable their elimination by mitophagy, stressing the importance of fission in the process of mtDNA quality control. The role of fusion is more multifaceted and less understood in this context, but the mixing and equilibration of matrix content might be one of its important functions.
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Affiliation(s)
- Karin B Busch
- Division of Mitochondrial Dynamics, School of Biology and Chemistry, University of Osnabrück, 49069 Osnabrück, Germany
| | - Axel Kowald
- Centre for Integrated Systems Biology of Ageing and Nutrition, Institute for Ageing and Health, Newcastle University, Campus for Ageing and Vitality, Newcastle upon Tyne NE4 5PL, UK
| | - Johannes N Spelbrink
- Department of Pediatrics, Nijmegen Centre for Mitochondrial Disorders, Radboud University Medical Centre, Geert Grooteplein 10, PO Box 9101, 6500 HB Nijmegen, The Netherlands FinMIT Centre of Excellence, Institute of Biomedical Technology and Tampere University Hospital, Pirkanmaa Hospital District, 33014 Tampere, Finland
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Menendez JA, Joven J. Energy metabolism and metabolic sensors in stem cells: the metabostem crossroads of aging and cancer. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 824:117-40. [PMID: 25038997 DOI: 10.1007/978-3-319-07320-0_10] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
We are as old as our adult stem cells are; therefore, stem cell exhaustion is considered a hallmark of aging. Our tumors are as aggressive as the number of cancer stem cells (CSCs) they bear because CSCs can survive treatments with hormones, radiation, chemotherapy, and molecularly targeted drugs, thus increasing the difficulty of curing cancer. Not surprisingly, interest in stem cell research has never been greater among members of the public, politicians, and scientists. But how can we slow the rate at which our adult stem cells decline over our lifetime, reducing the regenerative potential of tissues, while efficiently eliminating the aberrant, life-threatening activity of "selfish", immortal, and migrating CSCs? Frustrated by the gene-centric limitations of conventional approaches to aging diseases, our group and other groups have begun to appreciate that bioenergetic metabolism, i.e., the production of fuel & building blocks for growth and division, and autophagy/mitophagy, i.e., the quality-control, self-cannibalistic system responsible for "cleaning house" and "recycling the trash", can govern the genetic and epigenetic networks that facilitate stem cell behaviors. Indeed, it is reasonable to suggest the existence of a "metabostem" infrastructure that operates as a shared hallmark of aging and cancer, thus making it physiologically plausible to maintain or even increase the functionality of adult stem cells while reducing the incidence of cancer and extending the lifespan. This "metabostemness" property could lead to the discovery of new drugs that reprogram cell metabotypes to increase the structural and functional integrity of adult stem cells and positively influence their lineage determination, while preventing the development and aberrant function of stem cells in cancer tissues. While it is obvious that the antifungal antibiotic rapamycin, the polyphenol resveratrol, and the biguanide metformin already belong to this new family of metabostemness-targeting drugs, we can expect a rapid identification of new drug candidates (e.g., polyphenolic xenohormetins) that reverse or postpone "geroncogenesis", i.e., aging-induced metabolic decline as a driver of tumorigenesis, at the stem cell level.
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Affiliation(s)
- Javier A Menendez
- Metabolism & Cancer Group, Translational Research Laboratory, Catalan Institute of Oncology, Girona, Spain,
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Abstract
Somatic mitochondrial DNA (mtDNA) mutations contribute to the pathogenesis of age-related disorders, including myelodysplastic syndromes (MDS). The accumulation of mitochondria harboring mtDNA mutations in patients with these disorders suggests a failure of normal mitochondrial quality-control systems. The mtDNA-mutator mice acquire somatic mtDNA mutations via a targeted defect in the proofreading function of the mtDNA polymerase, PolgA, and develop macrocytic anemia similar to that of patients with MDS. We observed an unexpected defect in clearance of dysfunctional mitochondria at specific stages during erythroid maturation in hematopoietic cells from aged mtDNA-mutator mice. Mechanistically, aberrant activation of mechanistic target of rapamycin signaling and phosphorylation of uncoordinated 51-like kinase (ULK) 1 in mtDNA-mutator mice resulted in proteasome-mediated degradation of ULK1 and inhibition of autophagy in erythroid cells. To directly evaluate the consequence of inhibiting autophagy on mitochondrial function in erythroid cells harboring mtDNA mutations in vivo, we deleted Atg7 from erythroid progenitors of wild-type and mtDNA-mutator mice. Genetic disruption of autophagy did not cause anemia in wild-type mice but accelerated the decline in mitochondrial respiration and development of macrocytic anemia in mtDNA-mutator mice. These findings highlight a pathological feedback loop that explains how dysfunctional mitochondria can escape autophagy-mediated degradation and propagate in cells predisposed to somatic mtDNA mutations, leading to disease.
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61
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Mitochondrial function and mitochondrial DNA maintenance with advancing age. Biogerontology 2014; 15:417-38. [PMID: 25015781 DOI: 10.1007/s10522-014-9515-2] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2014] [Accepted: 07/01/2014] [Indexed: 12/24/2022]
Abstract
We review the impact of mitochondrial DNA (mtDNA) maintenance and mitochondrial function on the aging process. Mitochondrial function and mtDNA integrity are closely related. In order to create a protective barrier against reactive oxygen and nitrogen species (RONS) attacks and ensure mtDNA integrity, multiple cellular mtDNA copies are packaged together with various proteins in nucleoids. Regulation of antioxidant and RONS balance, DNA base excision repair, and selective degradation of damaged mtDNA copies preserves normal mtDNA quantities. Oxidative damage to mtDNA molecules does not substantially contribute to increased mtDNA mutation frequency; rather, mtDNA replication errors of DNA PolG are the main source of mtDNA mutations. Mitochondrial turnover is the major contributor to maintenance of mtDNA and functionally active mitochondria. Mitochondrial turnover involves mitochondrial biogenesis, mitochondrial dynamics, and selective autophagic removal of dysfunctional mitochondria (i.e., mitophagy). All of these processes exhibit decreased activity during aging and fall under greater nuclear genome control, possibly coincident with the emergence of nuclear genome instability. We suggest that the age-dependent accumulation of mutated mtDNA copies and dysfunctional mitochondria is associated primarily with decreased cellular autophagic and mitophagic activity.
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Procaccio V, Bris C, Chao de la Barca J, Oca F, Chevrollier A, Amati-Bonneau P, Bonneau D, Reynier P. Perspectives of drug-based neuroprotection targeting mitochondria. Rev Neurol (Paris) 2014; 170:390-400. [DOI: 10.1016/j.neurol.2014.03.005] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2014] [Accepted: 03/25/2014] [Indexed: 01/20/2023]
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Affiliation(s)
- Scott B Vafai
- Howard Hughes Medical Institute, Departments of Molecular Biology and Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
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