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Cerantonio A, Citrigno L, Greco BM, De Benedittis S, Passarino G, Maletta R, Qualtieri A, Montesanto A, Spadafora P, Cavalcanti F. The Role of Mitochondrial Copy Number in Neurodegenerative Diseases: Present Insights and Future Directions. Int J Mol Sci 2024; 25:6062. [PMID: 38892250 PMCID: PMC11172615 DOI: 10.3390/ijms25116062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2024] [Revised: 05/21/2024] [Accepted: 05/29/2024] [Indexed: 06/21/2024] Open
Abstract
Neurodegenerative diseases are progressive disorders that affect the central nervous system (CNS) and represent the major cause of premature death in the elderly. One of the possible determinants of neurodegeneration is the change in mitochondrial function and content. Altered levels of mitochondrial DNA copy number (mtDNA-CN) in biological fluids have been reported during both the early stages and progression of the diseases. In patients affected by neurodegenerative diseases, changes in mtDNA-CN levels appear to correlate with mitochondrial dysfunction, cognitive decline, disease progression, and ultimately therapeutic interventions. In this review, we report the main results published up to April 2024, regarding the evaluation of mtDNA-CN levels in blood samples from patients affected by Alzheimer's (AD), Parkinson's (PD), and Huntington's diseases (HD), amyotrophic lateral sclerosis (ALS), and multiple sclerosis (MS). The aim is to show a probable link between mtDNA-CN changes and neurodegenerative disorders. Understanding the causes underlying this association could provide useful information on the molecular mechanisms involved in neurodegeneration and offer the development of new diagnostic approaches and therapeutic interventions.
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Affiliation(s)
- Annamaria Cerantonio
- Institute for Biomedical Research and Innovation, National Research Council (IRIB-CNR), 87050 Mangone, CS, Italy; (A.C.); (P.S.)
| | - Luigi Citrigno
- Institute for Biomedical Research and Innovation, National Research Council (IRIB-CNR), 87050 Mangone, CS, Italy; (A.C.); (P.S.)
| | - Beatrice Maria Greco
- Institute for Biomedical Research and Innovation, National Research Council (IRIB-CNR), 87050 Mangone, CS, Italy; (A.C.); (P.S.)
- Department of Biology, Ecology and Earth Sciences, University of Calabria, 87036 Rende, CS, Italy
| | - Selene De Benedittis
- Institute for Biomedical Research and Innovation, National Research Council (IRIB-CNR), 87050 Mangone, CS, Italy; (A.C.); (P.S.)
| | - Giuseppe Passarino
- Department of Biology, Ecology and Earth Sciences, University of Calabria, 87036 Rende, CS, Italy
| | - Raffaele Maletta
- Regional Neurogenetic Centre (CRN), Department of Primary Care, ASP Catanzaro, 88046 Lamezia Terme, CZ, Italy
- Association for Neurogenetic Research (ARN), 88046 Lamezia Terme, CZ, Italy
| | - Antonio Qualtieri
- Institute for Biomedical Research and Innovation, National Research Council (IRIB-CNR), 87050 Mangone, CS, Italy; (A.C.); (P.S.)
| | - Alberto Montesanto
- Department of Biology, Ecology and Earth Sciences, University of Calabria, 87036 Rende, CS, Italy
| | - Patrizia Spadafora
- Institute for Biomedical Research and Innovation, National Research Council (IRIB-CNR), 87050 Mangone, CS, Italy; (A.C.); (P.S.)
| | - Francesca Cavalcanti
- Institute for Biomedical Research and Innovation, National Research Council (IRIB-CNR), 87050 Mangone, CS, Italy; (A.C.); (P.S.)
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2
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Mechanisms of Mitochondrial Malfunction in Alzheimer’s Disease: New Therapeutic Hope. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2022; 2022:4759963. [PMID: 35607703 PMCID: PMC9124149 DOI: 10.1155/2022/4759963] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/20/2022] [Revised: 04/08/2022] [Accepted: 04/16/2022] [Indexed: 02/05/2023]
Abstract
Mitochondria play a critical role in neuron viability or death as it regulates energy metabolism and cell death pathways. They are essential for cellular energy metabolism, reactive oxygen species production, apoptosis, Ca++ homeostasis, aging, and regeneration. Mitophagy and mitochondrial dynamics are thus essential processes in the quality control of mitochondria. Improvements in several fundamental features of mitochondrial biology in susceptible neurons of AD brains and the putative underlying mechanisms of such changes have made significant progress. AD's etiology has been reported by mitochondrial malfunction and oxidative damage. According to several recent articles, a continual fusion and fission balance of mitochondria is vital in their normal function maintenance. As a result, the shape and function of mitochondria are inextricably linked. This study examines evidence suggesting that mitochondrial dysfunction plays a significant early impact on AD pathology. Furthermore, the dynamics and roles of mitochondria are discussed with the link between mitochondrial malfunction and autophagy in AD has also been explored. In addition, recent research on mitochondrial dynamics and mitophagy in AD is also discussed in this review. It also goes into how these flaws affect mitochondrial quality control. Furthermore, advanced therapy techniques and lifestyle adjustments that lead to improved management of the dynamics have been demonstrated, hence improving the conditions that contribute to mitochondrial dysfunction in AD.
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3
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Wilkins HM, Swerdlow RH. Mitochondrial links between brain aging and Alzheimer's disease. Transl Neurodegener 2021; 10:33. [PMID: 34465385 PMCID: PMC8408998 DOI: 10.1186/s40035-021-00261-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Accepted: 08/21/2021] [Indexed: 02/08/2023] Open
Abstract
Advancing age is a major risk factor for Alzheimer's disease (AD). This raises the question of whether AD biology mechanistically diverges from aging biology or alternatively represents exaggerated aging. Correlative and modeling studies can inform this question, but without a firm grasp of what drives aging and AD it is difficult to definitively resolve this quandary. This review speculates over the relevance of a particular hallmark of aging, mitochondrial function, to AD, and further provides background information that is pertinent to and provides perspective on this speculation.
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Affiliation(s)
- Heather M Wilkins
- University of Kansas Alzheimer's Disease Research Center, Kansas City, KS, USA
- Departments of Neurology, University of Kansas Medical Center, Kansas City, KS, USA
- Departments of Biochemistry and Molecular Biology, Medical Center, University of Kansas Medical Center, Kansas City, USA
| | - Russell H Swerdlow
- University of Kansas Alzheimer's Disease Research Center, Kansas City, KS, USA.
- Departments of Neurology, University of Kansas Medical Center, Kansas City, KS, USA.
- Departments of Biochemistry and Molecular Biology, Medical Center, University of Kansas Medical Center, Kansas City, USA.
- Departments of Molecular and Integrative Physiology, Medical Center, University of Kansas Medical Center, Kansas City, KS, USA.
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4
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Snyder RJ, Kleeberger SR. Role of Mitochondrial DNA in Inflammatory Airway Diseases. Compr Physiol 2021; 11:1485-1499. [PMID: 33577124 DOI: 10.1002/cphy.c200010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The mitochondrial genome is a small, circular, and highly conserved piece of DNA which encodes only 13 protein subunits yet is vital for electron transport in the mitochondrion and, therefore, vital for the existence of multicellular life on Earth. Despite this importance, mitochondrial DNA (mtDNA) is located in one of the least-protected areas of the cell, exposing it to high concentrations of intracellular reactive oxygen species (ROS) and threat from exogenous substances and pathogens. Until recently, the quality control mechanisms which ensured the stability of the nuclear genome were thought to be minimal or nonexistent in the mitochondria, and the thousands of redundant copies of mtDNA in each cell were believed to be the primary mechanism of protecting these genes. However, a vast network of mechanisms has been discovered that repair mtDNA lesions, replace and recycle mitochondrial chromosomes, and conduct alternate RNA processing for previously undescribed mitochondrial proteins. New mtDNA/RNA-dependent signaling pathways reveal a mostly undiscovered biochemical landscape in which the mitochondria interface with their host cells/organisms. As the myriad ways in which the function of the mitochondrial genome can affect human health have become increasingly apparent, the use of mitogenomic biomarkers (such as copy number and heteroplasmy) as toxicological endpoints has become more widely accepted. In this article, we examine several pathologies of human airway epithelium, including particle exposures, inflammatory diseases, and hyperoxia, and discuss the role of mitochondrial genotoxicity in the pathogenesis and/or exacerbation of these conditions. © 2021 American Physiological Society. Compr Physiol 11:1485-1499, 2021.
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Affiliation(s)
- Ryan J Snyder
- National Institute of Environmental Health Sciences, NIH, Durham, North Carolina, USA
| | - Steven R Kleeberger
- National Institute of Environmental Health Sciences, NIH, Durham, North Carolina, USA
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5
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Iketani G, Pimentel L, Torres EDS, Rêgo PSD, Sampaio I. Mitochondrial heteroplasmy and pseudogenes in the freshwater prawn, Macrobrachium amazonicum (Heller, 1862): DNA barcoding and phylogeographic implications. Mitochondrial DNA A DNA Mapp Seq Anal 2020; 32:1-11. [PMID: 33164622 DOI: 10.1080/24701394.2020.1844677] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The mitochondrial cytochrome oxidase c subunit 1 (COI) gene has been widely used in phylogenetic studies of crustaceans and analyses in population genetics. As COI studies have become more popular, there has been an increase in the number of reports of the presence of nuclear insertions of mitochondrial DNA (Numts) and mitochondrial heteroplasmy. Here, we provide evidence of both types of event in the COI sequences of Macrobrachium amazonicum, an economically important freshwater prawn, which is widespread in South America. Heteroplasmy and Numts were confirmed by different methods of DNA extraction (genomic, mitochondrial, and nuclear-enriched DNA), cloning, and sequencing, and were observed in 11 of the 14 populations sampled, primarily in the Amazon region. We discuss how the occurrence of these events affects the interpretation of the genetic relationships among the M. amazonicum populations, and we recommend caution when using COI for genetic inferences in prawns of the genus Macrobrachium, and in particular that any analysis should include nuclear markers.
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Affiliation(s)
- Gabriel Iketani
- Laboratório de Educação e Evolução Prof. Horacio Schneider, Instituto de Ciências da Educação, Universidade Federal do Oeste do Pará, Santarém, Brasil
| | - Luciana Pimentel
- Laboratório de Educação e Evolução Prof. Horacio Schneider, Instituto de Ciências da Educação, Universidade Federal do Oeste do Pará, Santarém, Brasil
| | - Ezequias Dos Santos Torres
- Laboratório de Educação e Evolução Prof. Horacio Schneider, Instituto de Ciências da Educação, Universidade Federal do Oeste do Pará, Santarém, Brasil
| | - Péricles Sena do Rêgo
- Laboratório de Genética e Conservação, Instituto de Estudos Costeiros, Universidade Federal do Pará, Bragança, Brasil.,CIBIO-InBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, Universidade do Porto, Vairão, Portugal
| | - Iracilda Sampaio
- Laboratório de Genética e Biologia Molecular, Instituto de Estudos Costeiros, Universidade Federal do Pará, Bragança, Brasil
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6
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Mitochondrial Inheritance in Phytopathogenic Fungi-Everything Is Known, or Is It? Int J Mol Sci 2020; 21:ijms21113883. [PMID: 32485941 PMCID: PMC7312866 DOI: 10.3390/ijms21113883] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Revised: 05/26/2020] [Accepted: 05/28/2020] [Indexed: 12/19/2022] Open
Abstract
Mitochondria are important organelles in eukaryotes that provide energy for cellular processes. Their function is highly conserved and depends on the expression of nuclear encoded genes and genes encoded in the organellar genome. Mitochondrial DNA replication is independent of the replication control of nuclear DNA and as such, mitochondria may behave as selfish elements, so they need to be controlled, maintained and reliably inherited to progeny. Phytopathogenic fungi meet with special environmental challenges within the plant host that might depend on and influence mitochondrial functions and services. We find that this topic is basically unexplored in the literature, so this review largely depends on work published in other systems. In trying to answer elemental questions on mitochondrial functioning, we aim to introduce the aspect of mitochondrial functions and services to the study of plant-microbe-interactions and stimulate phytopathologists to consider research on this important organelle in their future projects.
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7
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Yoo SM, Park J, Kim SH, Jung YK. Emerging perspectives on mitochondrial dysfunction and inflammation in Alzheimer's disease. BMB Rep 2020. [PMID: 31818363 PMCID: PMC6999830 DOI: 10.5483/bmbrep.2020.53.1.274] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Despite enduring diverse insults, mitochondria maintain normal functions through mitochondrial quality control. However, the failure of mitochondrial quality control resulting from excess damage and mechanical defects causes mitochondrial dysfunction, leading to various human diseases. Recent studies have reported that mitochondrial defects are found in Alzheimer’s disease (AD) and worsen AD symptoms. In AD pathogenesis, mitochondrial dysfunction-driven generation of reactive oxygen species (ROS) and their contribution to neuronal damage has been widely studied. In contrast, studies on mitochondrial dysfunction-associated inflammatory responses have been relatively scarce. Moreover, ROS produced upon failure of mitochondrial quality control may be linked to the inflammatory response and influence the progression of AD. Thus, this review will focus on inflammatory pathways that are associated with and initiated through defective mitochondria and will summarize recent progress on the role of mitochondria-mediated inflammation in AD. We will also discuss how reducing mitochondrial dysfunction-mediated inflammation could affect AD.
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Affiliation(s)
- Seung-Min Yoo
- School of Biological Sciences, Seoul National University, Seoul 08826, Korea
| | - Jisu Park
- School of Biological Sciences, Seoul National University, Seoul 08826, Korea
| | - Seo-Hyun Kim
- School of Biological Sciences, Seoul National University, Seoul 08826, Korea
| | - Yong-Keun Jung
- School of Biological Sciences, Seoul National University, Seoul 08826, Korea
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8
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Gonzalez‐Freire M, Moore AZ, Peterson CA, Kosmac K, McDermott MM, Sufit RL, Guralnik JM, Polonsky T, Tian L, Kibbe MR, Criqui MH, Li L, Leeuwenburgh C, Ferrucci L. Associations of Peripheral Artery Disease With Calf Skeletal Muscle Mitochondrial DNA Heteroplasmy. J Am Heart Assoc 2020; 9:e015197. [PMID: 32200714 PMCID: PMC7428597 DOI: 10.1161/jaha.119.015197] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Accepted: 02/24/2020] [Indexed: 12/13/2022]
Abstract
Background Patients with peripheral artery disease (PAD) undergo frequent episodes of ischemia-reperfusion in lower extremity muscles that may negatively affect mitochondrial health and are associated with impaired mobility. We hypothesized that skeletal muscle from PAD patients will show high mitochondrial DNA heteroplasmy, especially in regions more susceptible to oxidative damage, such as the displacement loop, and that the degree of heteroplasmy will be correlated with the severity of ischemia and mobility impairment. Methods and Results Mitochondrial mutations and deletions and their relative abundance were identified by targeted mitochondrial DNA sequencing in biopsy specimens of gastrocnemius muscle from 33 PAD (ankle brachial index <0.9) and 9 non-PAD (ankle brachial index >0.9) subjects aged ≥60 years. The probability of heteroplasmy per DNA base was significantly higher for PAD subjects than non-PAD within each region. In adjusted models, PAD was associated with higher heteroplasmy than non-PAD (P=0.003), but the association was limited to microheteroplasmy, that is heteroplasmy found in 1% to 5% of all mitochondrial genomes (P=0.004). Heteroplasmy in the displacement loop and coding regions were significantly higher for PAD than non-PAD subjects after adjustment for age, sex, race, and diabetes mellitus (P=0.037 and 0.004, respectively). Low mitochondrial damage, defined by both low mitochondrial DNA copy number and low microheteroplasmy, was associated with better walking performance. Conclusions People with PAD have higher "low frequency" heteroplasmy in gastrocnemius muscle compared with people without PAD. Among people with PAD, those who had evidence of least mitochondrial damage, had better walking performance than those with more mitochondrial damage. Registration URL: http://www.clinicaltrials.gov. Unique identifier: NCT02246660.
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Affiliation(s)
- Marta Gonzalez‐Freire
- National Institutes on HealthNational Institute on AgingBaltimoreMD
- Health Research Institute of the Balearic Islands (IdISBa)Palma de MallorcaIlles BalearsSpain
| | - A. Zenobia Moore
- National Institutes on HealthNational Institute on AgingBaltimoreMD
| | - Charlotte A. Peterson
- College of Health Sciences and Center for Muscle BiologyUniversity of KentuckyLexingtonKY
| | - Kate Kosmac
- College of Health Sciences and Center for Muscle BiologyUniversity of KentuckyLexingtonKY
| | - Mary M. McDermott
- Department of MedicineNorthwestern University Feinberg School of MedicineChicagoIL
- Department of Preventive MedicineNorthwestern University Feinberg School of MedicineChicagoIL
| | - Robert L. Sufit
- Department of NeurologyNorthwestern University Feinberg School of MedicineChicagoIL
| | | | | | - Lu Tian
- Department of Health Research & PolicyStanford UniversityStanfordCA
| | | | - Michael H. Criqui
- Department of Family Medicine and Public HealthUniversity of California at San DiegoLa JollaCA
| | - Lingyu Li
- Department of MedicineNorthwestern University Feinberg School of MedicineChicagoIL
| | - Christian Leeuwenburgh
- Department of Aging and Geriatric ResearchUniversity of Florida Institute on AgingGainesvilleFL
| | - Luigi Ferrucci
- National Institutes on HealthNational Institute on AgingBaltimoreMD
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9
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da Silva Francisco Junior R, Dos Santos Ferreira C, Santos E Silva JC, Terra Machado D, Côrtes Martins Y, Ramos V, Simões Carnivali G, Garcia AB, Medina-Acosta E. Pervasive Inter-Individual Variation in Allele-Specific Expression in Monozygotic Twins. Front Genet 2019; 10:1178. [PMID: 31850058 PMCID: PMC6887657 DOI: 10.3389/fgene.2019.01178] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Accepted: 10/24/2019] [Indexed: 01/19/2023] Open
Abstract
Despite being developed from one zygote, heterokaryotypic monozygotic (MZ) co-twins exhibit discordant karyotypes. Epigenomic studies in biological samples from heterokaryotypic MZ co-twins are of the most significant value for assessing the effects on gene- and allele-specific expression of an extranumerary chromosomal copy or structural chromosomal disparities in otherwise nearly identical germline genetic contributions. Here, we use RNA-Seq data from existing repositories to establish within-pair correlations for the breadth and magnitude of allele-specific expression (ASE) in heterokaryotypic MZ co-twins discordant for trisomy 21 and maternal 21q inheritance, as well as homokaryotypic co-twins. We show that there is a genome-wide disparity at ASE sites between the heterokaryotypic MZ co-twins. Although most of the disparity corresponds to changes in the magnitude of biallelic imbalance, ASE sites switching from either strictly monoallelic to biallelic imbalance or the reverse occur in few genes that are known or predicted to be imprinted, subject to X-chromosome inactivation or A-to-I(G) RNA edited. We also uncovered comparable ASE differences between homokaryotypic MZ twins. The extent of ASE discordance in MZ twins (2.7%) was about 10-fold lower than the expected between pairs of unrelated, non-twin males or females. The results indicate that the observed within-pair dissimilarities in breadth and magnitude of ASE sites in the heterokaryotypic MZ co-twins could not solely be attributable to the aneuploidy and the missing allelic heritability at 21q.
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Affiliation(s)
| | - Cristina Dos Santos Ferreira
- Laboratório de Biotecnologia, Núcleo de Diagnóstico e Investigação Molecular, Universidade Estadual do Norte Fluminense, Campos dos Goytacazes, Brazil
| | - Juan Carlo Santos E Silva
- Laboratório de Biotecnologia, Núcleo de Diagnóstico e Investigação Molecular, Universidade Estadual do Norte Fluminense, Campos dos Goytacazes, Brazil
| | - Douglas Terra Machado
- Laboratório de Biotecnologia, Núcleo de Diagnóstico e Investigação Molecular, Universidade Estadual do Norte Fluminense, Campos dos Goytacazes, Brazil
| | - Yasmmin Côrtes Martins
- Laboratório de Bioinformática, Laboratório Nacional de Computação Científica, Petrópolis, Brazil
| | - Victor Ramos
- Department of Genetics, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, Brazil
| | - Gustavo Simões Carnivali
- Department of Computational Science, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Ana Beatriz Garcia
- Laboratório de Biotecnologia, Núcleo de Diagnóstico e Investigação Molecular, Universidade Estadual do Norte Fluminense, Campos dos Goytacazes, Brazil
| | - Enrique Medina-Acosta
- Laboratório de Biotecnologia, Núcleo de Diagnóstico e Investigação Molecular, Universidade Estadual do Norte Fluminense, Campos dos Goytacazes, Brazil
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10
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Scheid AD, Beadnell TC, Welch DR. The second genome: Effects of the mitochondrial genome on cancer progression. Adv Cancer Res 2019; 142:63-105. [PMID: 30885364 DOI: 10.1016/bs.acr.2019.01.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The role of genetics in cancer has been recognized for centuries, but most studies elucidating genetic contributions to cancer have understandably focused on the nuclear genome. Mitochondrial contributions to cancer pathogenesis have been documented for decades, but how mitochondrial DNA (mtDNA) influences cancer progression and metastasis remains poorly understood. This lack of understanding stems from difficulty isolating the nuclear and mitochondrial genomes as experimental variables, which is critical for investigating direct mtDNA contributions to disease given extensive crosstalk exists between both genomes. Several in vitro and in vivo models have isolated mtDNA as an independent variable from the nuclear genome. This review compares and contrasts different models, their advantages and disadvantages for studying mtDNA contributions to cancer, focusing on the mitochondrial-nuclear exchange (MNX) mouse model and findings regarding tumor progression, metastasis, and other complex cancer-related phenotypes.
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Affiliation(s)
- Adam D Scheid
- Department of Cancer Biology, The University of Kansas Medical Center, and The University of Kansas Cancer Center, Kansas City, KS, United States
| | - Thomas C Beadnell
- Department of Cancer Biology, The University of Kansas Medical Center, and The University of Kansas Cancer Center, Kansas City, KS, United States
| | - Danny R Welch
- Department of Cancer Biology, The University of Kansas Medical Center, and The University of Kansas Cancer Center, Kansas City, KS, United States.
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11
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Onyango IG. Modulation of mitochondrial bioenergetics as a therapeutic strategy in Alzheimer's disease. Neural Regen Res 2018; 13:19-25. [PMID: 29451200 PMCID: PMC5840984 DOI: 10.4103/1673-5374.224362] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/06/2018] [Indexed: 01/14/2023] Open
Abstract
Alzheimer's disease (AD) is an increasingly pressing worldwide public-health, social, political and economic concern. Despite significant investment in multiple traditional therapeutic strategies that have achieved success in preclinical models addressing the pathological hallmarks of the disease, these efforts have not translated into any effective disease-modifying therapies. This could be because interventions are being tested too late in the disease process. While existing therapies provide symptomatic and clinical benefit, they do not fully address the molecular abnormalities that occur in AD neurons. The pathophysiology of AD is complex; mitochondrial bioenergetic deficits and brain hypometabolism coupled with increased mitochondrial oxidative stress are antecedent and potentially play a causal role in the disease pathogenesis. Dysfunctional mitochondria accumulate from the combination of impaired mitophagy, which can also induce injurious inflammatory responses, and inadequate neuronal mitochondrial biogenesis. Altering the metabolic capacity of the brain by modulating/potentiating its mitochondrial bioenergetics may be a strategy for disease prevention and treatment. We present insights into the mechanisms of mitochondrial dysfunction in AD brain as well as an overview of emerging treatments with the potential to prevent, delay or reverse the neurodegenerative process by targeting mitochondria.
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12
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Sirt6 Promotes DNA End Joining in iPSCs Derived from Old Mice. Cell Rep 2017; 18:2880-2892. [PMID: 28329681 DOI: 10.1016/j.celrep.2017.02.082] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Revised: 01/22/2017] [Accepted: 02/28/2017] [Indexed: 12/11/2022] Open
Abstract
Induced pluripotent stem cells (iPSCs) have great potential for treating age-related diseases, but the genome integrity of iPSCs is critically important. Here, we demonstrate that non-homologous end joining (NHEJ), rather than homologous recombination (HR), is less efficient in iPSCs from old mice than young mice. We further find that Sirt6 is downregulated in iPSCs from old mice. Sirt6 directly binds to Ku80 and facilitates the Ku80/DNA-PKcs interaction, thus promoting DNA-PKcs phosphorylation at residue S2056, leading to efficient NHEJ. Rescue experiments show that introducing a combination of Sirt6 and the Yamanaka factors during reprogramming significantly promotes DNA double-strand break (DSB) repair by activating NHEJ in iPSCs derived from old mice. Thus, our study suggests a strategy to improve the quality of iPSCs derived from old donors by activating NHEJ and stabilizing the genome.
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13
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Zhao S, Samuels DC, Zhao YY, Guo Y. Tri-allelic heteroplasmies, DNA-RNA differences and their polynucleotide tract associations in the mitochondrial genome. Genomics 2017; 110:S0888-7543(17)30093-9. [PMID: 28970049 DOI: 10.1016/j.ygeno.2017.09.013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Revised: 09/20/2017] [Accepted: 09/27/2017] [Indexed: 12/29/2022]
Abstract
The human mitochondrial genome has been extensively studied for its function and disease associations. Utilizing five types of high-throughput sequencing data on ten breast cancer patients (total N=50), we examined several aspects of the mitochondrial genome that have not been thoroughly studied, including the occurrence of tri-allelic heteroplasmy, the difference between DNA and RNA, and the variants association with polynucleotide tracts. We validated four previously reported and identified 23 additional tri-allelic positions. Furthermore, we detected 18 single nucleotide and seven InDel differences between DNA and RNA. Previous studies have suggested that some of these differences are caused by post transcriptional methylation. The rest can be accredited to RNA editing, polyadenylation or sequencing errors. Most importantly, we found that the tri-allelic positions, and differences between DNA and RNA, are strongly associated with polynucleotide tracts in the mitochondrial genome, suggesting DNA instability or difficulty sequencing around the polynucleotide tract regions.
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Affiliation(s)
- Shilin Zhao
- Department of Biostatistics, Vanderbilt University Medical Center, Nashville, TN 37232, United States
| | - David C Samuels
- Vanderbilt Genetics Institute, Dept. of Molecular Physiology and Biophysics, Vanderbilt University Medical School, Nashville, TN 37232, United States
| | - Ying-Yong Zhao
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education, School of Life Sciences, Northwest University, Xi'an, Shaanxi 710069, China
| | - Yan Guo
- Department of Biomedical Informatics, Vanderbilt University Medical Center, Nashville, TN 37232, United States; Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education, School of Life Sciences, Northwest University, Xi'an, Shaanxi 710069, China; Department of Internal Medicine, University of New Mexico, Comprehensive Cancer Center, Albuquerque, NM, 87131, United States.
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14
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Zaia A, Maponi P, Di Stefano G, Casoli T. Biocomplexity and Fractality in the Search of Biomarkers of Aging and Pathology: Focus on Mitochondrial DNA and Alzheimer's Disease. Aging Dis 2017; 8:44-56. [PMID: 28197358 PMCID: PMC5291006 DOI: 10.14336/ad.2016.0629] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Accepted: 06/29/2016] [Indexed: 12/14/2022] Open
Abstract
Alzheimer’s disease (AD) represents one major health concern for our growing elderly population. It accounts for increasing impairment of cognitive capacity followed by loss of executive function in late stage. AD pathogenesis is multifaceted and difficult to pinpoint, and understanding AD etiology will be critical to effectively diagnose and treat the disease. An interesting hypothesis concerning AD development postulates a cause-effect relationship between accumulation of mitochondrial DNA (mtDNA) mutations and neurodegenerative changes associated with this pathology. Here we propose a computerized method for an easy and fast mtDNA mutations-based characterization of AD. The method has been built taking into account the complexity of living being and fractal properties of many anatomic and physiologic structures, including mtDNA. Dealing with mtDNA mutations as gaps in the nucleotide sequence, fractal lacunarity appears a suitable tool to differentiate between aging and AD. Therefore, Chaos Game Representation method has been used to display DNA fractal properties after adapting the algorithm to visualize also heteroplasmic mutations. Parameter β from our fractal lacunarity method, based on hyperbola model function, has been measured to quantitatively characterize AD on the basis of mtDNA mutations. Results from this pilot study to develop the method show that fractal lacunarity parameter β of mtDNA is statistically different in AD patients when compared to age-matched controls. Fractal lacunarity analysis represents a useful tool to analyze mtDNA mutations. Lacunarity parameter β is able to characterize individual mutation profile of mitochondrial genome and appears a promising index to discriminate between AD and aging.
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Affiliation(s)
- Annamaria Zaia
- 1Laboratory of Bioinformatics, Bioengineering and Domotics, Italian National Research Center on Aging - INRCA, via Birarelli 8, 60121 Ancona, Italy
| | - Pierluigi Maponi
- 2School of Science and Technology, University of Camerino, via Madonna delle Carceri 9, 62032 Camerino (MC), Italy
| | - Giuseppina Di Stefano
- 3Research, Innovation and Technology Transfer Office, Italian National Research Center on Aging - INRCA, via Birarelli 8, 60121 Ancona, Italy
| | - Tiziana Casoli
- 4Scientific and Technological Area, Italian National Research Center on Aging - INRCA, via Birarelli 8, 60121 Ancona, Italy
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15
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Williams DT, Staples CJ. Approaches for Identifying Novel Targets in Precision Medicine: Lessons from DNA Repair. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 1007:1-16. [PMID: 28840549 DOI: 10.1007/978-3-319-60733-7_1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Genome stability is maintained by a number of elegant mechanisms, which sense and repair damaged DNA. Germline defects that compromise genomic integrity result in cancer predisposition, exemplified by rare syndromes caused by mutations in certain DNA repair genes. These individuals often exhibit other symptoms including progeria and neurodegeneration. Paradoxically, some of these deleterious genetic alterations provide novel therapeutic opportunities to target cancer cells; an excellent example of such an approach being the recent development of poly (ADP-ribose) polymerase inhibitors as the first 'synthetic lethal' medicine for patients with BRCA-mutant cancers. The therapeutic exploitation of synthetic lethal interactions has enabled a novel approach to personalised medicine based on continued molecular profiling of patient and tumour material. This profiling may also aid clinicians in the identification of specific drug resistance mechanisms following relapse, and enable appropriate modification of the therapeutic regimen. This chapter focuses on therapeutic strategies designed to target aspects of the DNA damage response, and examines emerging themes demonstrating mechanistic overlap between DNA repair and neurodegeneration.
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Affiliation(s)
- Dean T Williams
- School of Medical Sciences, Bangor University, Bangor, Gwynedd, LL57 2DG, UK.,Department of Vascular Surgery, Ysbyty Gwynedd, Bangor, LL57 2PW, UK
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16
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Albayrak L, Khanipov K, Pimenova M, Golovko G, Rojas M, Pavlidis I, Chumakov S, Aguilar G, Chávez A, Widger WR, Fofanov Y. The ability of human nuclear DNA to cause false positive low-abundance heteroplasmy calls varies across the mitochondrial genome. BMC Genomics 2016; 17:1017. [PMID: 27955616 PMCID: PMC5153897 DOI: 10.1186/s12864-016-3375-x] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Accepted: 12/05/2016] [Indexed: 02/03/2023] Open
Abstract
Background Low-abundance mutations in mitochondrial populations (mutations with minor allele frequency ≤ 1%), are associated with cancer, aging, and neurodegenerative disorders. While recent progress in high-throughput sequencing technology has significantly improved the heteroplasmy identification process, the ability of this technology to detect low-abundance mutations can be affected by the presence of similar sequences originating from nuclear DNA (nDNA). To determine to what extent nDNA can cause false positive low-abundance heteroplasmy calls, we have identified mitochondrial locations of all subsequences that are common or similar (one mismatch allowed) between nDNA and mitochondrial DNA (mtDNA). Results Performed analysis revealed up to a 25-fold variation in the lengths of longest common and longest similar (one mismatch allowed) subsequences across the mitochondrial genome. The size of the longest subsequences shared between nDNA and mtDNA in several regions of the mitochondrial genome were found to be as low as 11 bases, which not only allows using these regions to design new, very specific PCR primers, but also supports the hypothesis of the non-random introduction of mtDNA into the human nuclear DNA. Conclusion Analysis of the mitochondrial locations of the subsequences shared between nDNA and mtDNA suggested that even very short (36 bases) single-end sequencing reads can be used to identify low-abundance variation in 20.4% of the mitochondrial genome. For longer (76 and 150 bases) reads, the proportion of the mitochondrial genome where nDNA presence will not interfere found to be 44.5 and 67.9%, when low-abundance mutations at 100% of locations can be identified using 417 bases long single reads. This observation suggests that the analysis of low-abundance variations in mitochondria population can be extended to a variety of large data collections such as NCBI Sequence Read Archive, European Nucleotide Archive, The Cancer Genome Atlas, and International Cancer Genome Consortium. Electronic supplementary material The online version of this article (doi:10.1186/s12864-016-3375-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Levent Albayrak
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX, 77555-0144, USA.,Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, TX, USA.,Department of Computer Science, University of Houston, Houston, TX, USA
| | - Kamil Khanipov
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX, 77555-0144, USA.,Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, TX, USA.,Department of Computer Science, University of Houston, Houston, TX, USA
| | - Maria Pimenova
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX, 77555-0144, USA.,Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, TX, USA
| | - George Golovko
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX, 77555-0144, USA.,Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, TX, USA
| | - Mark Rojas
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX, 77555-0144, USA.,Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, TX, USA
| | - Ioannis Pavlidis
- Department of Computer Science, University of Houston, Houston, TX, USA
| | - Sergei Chumakov
- Department of Physics, University of Guadalajara, Guadalajara, Jalisco, Mexico
| | - Gerardo Aguilar
- Department of Physics, University of Guadalajara, Guadalajara, Jalisco, Mexico
| | - Arturo Chávez
- Department of Physics, University of Guadalajara, Guadalajara, Jalisco, Mexico
| | - William R Widger
- Department of Biology and Biochemistry, University of Houston, Houston, TX, USA
| | - Yuriy Fofanov
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX, 77555-0144, USA. .,Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, TX, USA.
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17
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Unbiased Mitoproteome Analyses Confirm Non-canonical RNA, Expanded Codon Translations. Comput Struct Biotechnol J 2016; 14:391-403. [PMID: 27830053 PMCID: PMC5094600 DOI: 10.1016/j.csbj.2016.09.004] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Revised: 09/28/2016] [Accepted: 09/29/2016] [Indexed: 01/14/2023] Open
Abstract
Proteomic MS/MS mass spectrometry detections are usually biased towards peptides cleaved by experimentally added digestion enzyme(s). Hence peptides resulting from spontaneous degradation and natural proteolysis usually remain undetected. Previous analyses of tryptic human proteome data (cleavage after K, R) detected non-canonical tryptic peptides translated according to tetra- and pentacodons (codons expanded by silent mono- and dinucleotides), and from transcripts systematically (a) deleting mono-, dinucleotides after trinucleotides (delRNAs), (b) exchanging nucleotides according to 23 bijective transformations. Nine symmetric and fourteen asymmetric nucleotide exchanges (X ↔ Y, e.g. A ↔ C; and X → Y → Z → X, e.g. A → C → G → A) produce swinger RNAs. Here unbiased reanalyses of these proteomic data detect preferentially non-canonical tryptic peptides despite assuming random cleavage. Unbiased analyses couldn't reconstruct experimental tryptic digestion if most detected non-canonical peptides were false positives. Detected non-tryptic non-canonical peptides map preferentially on corresponding, previously described non-canonical transcripts, as for tryptic non-canonical peptides. Hence unbiased analyses independently confirm previous trypsin-biased analyses that showed translations of del- and swinger RNA and expanded codons. Accounting for natural proteolysis completes trypsin-biased mitopeptidome analyses, independently confirms non-canonical transcriptions and translations.
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18
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Chimeric mitochondrial peptides from contiguous regular and swinger RNA. Comput Struct Biotechnol J 2016; 14:283-97. [PMID: 27453772 PMCID: PMC4942731 DOI: 10.1016/j.csbj.2016.06.005] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Revised: 06/19/2016] [Accepted: 06/23/2016] [Indexed: 12/20/2022] Open
Abstract
Previous mass spectrometry analyses described human mitochondrial peptides entirely translated from swinger RNAs, RNAs where polymerization systematically exchanged nucleotides. Exchanges follow one among 23 bijective transformation rules, nine symmetric exchanges (X ↔ Y, e.g. A ↔ C) and fourteen asymmetric exchanges (X → Y → Z → X, e.g. A → C → G → A), multiplying by 24 DNA's protein coding potential. Abrupt switches from regular to swinger polymerization produce chimeric RNAs. Here, human mitochondrial proteomic analyses assuming abrupt switches between regular and swinger transcriptions, detect chimeric peptides, encoded by part regular, part swinger RNA. Contiguous regular- and swinger-encoded residues within single peptides are stronger evidence for translation of swinger RNA than previously detected, entirely swinger-encoded peptides: regular parts are positive controls matched with contiguous swinger parts, increasing confidence in results. Chimeric peptides are 200 × rarer than swinger peptides (3/100,000 versus 6/1000). Among 186 peptides with > 8 residues for each regular and swinger parts, regular parts of eleven chimeric peptides correspond to six among the thirteen recognized, mitochondrial protein-coding genes. Chimeric peptides matching partly regular proteins are rarer and less expressed than chimeric peptides matching non-coding sequences, suggesting targeted degradation of misfolded proteins. Present results strengthen hypotheses that the short mitogenome encodes far more proteins than hitherto assumed. Entirely swinger-encoded proteins could exist. Chimeric peptides are translated from contiguous regular and swinger RNA They are 200x rarer than mitochondrial swinger peptides Chimeric peptides integrated in regular mitochondrial proteins are downregulated Contiguous regular parts are matched positive controls for swinger parts The last point validates results beyond other statistical tests for robustness
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19
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Zhang P, Samuels DC, Wang J, Zhao S, Shyr Y, Guo Y. Mitochondria single nucleotide variation across six blood cell types. Mitochondrion 2016; 28:16-22. [PMID: 26956645 DOI: 10.1016/j.mito.2016.03.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2016] [Revised: 02/11/2016] [Accepted: 03/01/2016] [Indexed: 01/02/2023]
Abstract
It has been shown that heteroplasmic mitochondrial DNA variants can be tissue specific. However, whether mitochondrial DNA variants are specific by blood cell types has not been investigated. Motivated by this question and using mitochondria sequences extracted from RNAseq data from six distinct blood cell types (neutrophil, monocyte, myeloid dendritic, natural killer, T and B), we thoroughly compared SNPs and heteroplasmies among these cell types. Each cell type from each subject was sequenced at four time points used as biological replicates. We found that mitochondria content is low in neutrophil compared to the other five blood cell types. Subsequent analysis on the other five blood cell types showed that at the SNP level, there was no discrepancy. At the heteroplasmy level, we observed good concordances among all blood cell types. However, the allele frequencies of the heteroplasmy differed between blood cell types for certain heteroplasmic sites. Furthermore, we identified five tri-allelic sites (1610, 2617, 8303, 12146, 13710) that are likely caused by RNA editing. Three out of these five sites are located at the ninth position of tRNA genes, and are likely resulting from post-transcriptional methylation.
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Affiliation(s)
- Pan Zhang
- Department of Cancer Biology, Vanderbilt University, Nashville, TN 37232, USA
| | - David C Samuels
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Jing Wang
- Department of Cancer Biology, Vanderbilt University, Nashville, TN 37232, USA
| | - Shilin Zhao
- Department of Cancer Biology, Vanderbilt University, Nashville, TN 37232, USA
| | - Yu Shyr
- Department of Biostatistics, Vanderbilt University, Nashville, TN 37232, USA
| | - Yan Guo
- Department of Cancer Biology, Vanderbilt University, Nashville, TN 37232, USA
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20
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Halley YA, Oldeschulte DL, Bhattarai EK, Hill J, Metz RP, Johnson CD, Presley SM, Ruzicka RE, Rollins D, Peterson MJ, Murphy WJ, Seabury CM. Northern Bobwhite (Colinus virginianus) Mitochondrial Population Genomics Reveals Structure, Divergence, and Evidence for Heteroplasmy. PLoS One 2015; 10:e0144913. [PMID: 26713762 PMCID: PMC4699210 DOI: 10.1371/journal.pone.0144913] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2015] [Accepted: 11/26/2015] [Indexed: 01/09/2023] Open
Abstract
Herein, we evaluated the concordance of population inferences and conclusions resulting from the analysis of short mitochondrial fragments (i.e., partial or complete D-Loop nucleotide sequences) versus complete mitogenome sequences for 53 bobwhites representing six ecoregions across TX and OK (USA). Median joining (MJ) haplotype networks demonstrated that analyses performed using small mitochondrial fragments were insufficient for estimating the true (i.e., complete) mitogenome haplotype structure, corresponding levels of divergence, and maternal population history of our samples. Notably, discordant demographic inferences were observed when mismatch distributions of partial (i.e., partial D-Loop) versus complete mitogenome sequences were compared, with the reduction in mitochondrial genomic information content observed to encourage spurious inferences in our samples. A probabilistic approach to variant prediction for the complete bobwhite mitogenomes revealed 344 segregating sites corresponding to 347 total mutations, including 49 putative nonsynonymous single nucleotide variants (SNVs) distributed across 12 protein coding genes. Evidence of gross heteroplasmy was observed for 13 bobwhites, with 10 of the 13 heteroplasmies involving one moderate to high frequency SNV. Haplotype network and phylogenetic analyses for the complete bobwhite mitogenome sequences revealed two divergent maternal lineages (dXY = 0.00731; FST = 0.849; P < 0.05), thereby supporting the potential for two putative subspecies. However, the diverged lineage (n = 103 variants) almost exclusively involved bobwhites geographically classified as Colinus virginianus texanus, which is discordant with the expectations of previous geographic subspecies designations. Tests of adaptive evolution for functional divergence (MKT), frequency distribution tests (D, FS) and phylogenetic analyses (RAxML) provide no evidence for positive selection or hybridization with the sympatric scaled quail (Callipepla squamata) as being explanatory factors for the two bobwhite maternal lineages observed. Instead, our analyses support the supposition that two diverged maternal lineages have survived from pre-expansion to post-expansion population(s), with the segregation of some slightly deleterious nonsynonymous mutations.
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Affiliation(s)
- Yvette A. Halley
- Department of Veterinary Pathobiology, College of Veterinary Medicine, Texas A&M University, College Station, Texas, United States of America
| | - David L. Oldeschulte
- Department of Veterinary Pathobiology, College of Veterinary Medicine, Texas A&M University, College Station, Texas, United States of America
| | - Eric K. Bhattarai
- Department of Veterinary Pathobiology, College of Veterinary Medicine, Texas A&M University, College Station, Texas, United States of America
| | - Joshua Hill
- Genomics and Bioinformatics Core, Texas A&M AgriLife Research, College Station, Texas, United States of America
| | - Richard P. Metz
- Genomics and Bioinformatics Core, Texas A&M AgriLife Research, College Station, Texas, United States of America
| | - Charles D. Johnson
- Genomics and Bioinformatics Core, Texas A&M AgriLife Research, College Station, Texas, United States of America
| | - Steven M. Presley
- Department of Environmental Toxicology, Institute of Environmental and Human Health, Texas Tech University, Lubbock, Texas, United States of America
| | - Rebekah E. Ruzicka
- Texas A&M AgriLife Extension Service, Dallas, Texas, United States of America
| | - Dale Rollins
- Rolling Plains Quail Research Ranch, 1262 U.S. Highway 180 W., Rotan, Texas, United States of America
| | - Markus J. Peterson
- Department of Biological Sciences, University of Texas at El Paso, El Paso, Texas, United States of America
| | - William J. Murphy
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine, Texas A&M University, College Station, Texas, United States of America
| | - Christopher M. Seabury
- Department of Veterinary Pathobiology, College of Veterinary Medicine, Texas A&M University, College Station, Texas, United States of America
- * E-mail:
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21
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Abstract
Impaired mitochondrial structure and function are common features of neurodegenerative disorders, ultimately characterized by the death of neural cells promoted by still unknown signals. Among the possible modulators of neurodegeneration, the activation of poly(ADP-ribosylation), a post-translational modification of proteins, has been considered, being the product of the reaction, poly(ADP-ribose), a signaling molecule for different cell death paradigms. The basic properties of poly(ADP-ribosylation) are here described, focusing on the mitochondrial events; cell death paradigms such as apoptosis, parthanatos, necroptosis and mitophagy are illustrated. Finally, the promising use of poly(ADP-ribosylation) inhibitors to rescue neurodegeneration is addressed.
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Affiliation(s)
| | - Anna Ivana Scovassi
- Istituto di Genetica Molecolare CNR, Via Abbiategrasso 207, 27100 Pavia, Italy.
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22
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Rodriguez M, Rodriguez-Sabate C, Morales I, Sanchez A, Sabate M. Parkinson's disease as a result of aging. Aging Cell 2015; 14:293-308. [PMID: 25677794 PMCID: PMC4406659 DOI: 10.1111/acel.12312] [Citation(s) in RCA: 136] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/16/2014] [Indexed: 12/15/2022] Open
Abstract
It is generally considered that Parkinson's disease is induced by specific agents that degenerate a clearly defined population of dopaminergic neurons. Data commented in this review suggest that this assumption is not as clear as is often thought and that aging may be critical for Parkinson's disease. Neurons degenerating in Parkinson's disease also degenerate in normal aging, and the different agents involved in the etiology of this illness are also involved in aging. Senescence is a wider phenomenon affecting cells all over the body, whereas Parkinson's disease seems to be restricted to certain brain centers and cell populations. However, reviewed data suggest that Parkinson's disease may be a local expression of aging on cell populations which, by their characteristics (high number of synaptic terminals and mitochondria, unmyelinated axons, etc.), are highly vulnerable to the agents promoting aging. The development of new knowledge about Parkinson's disease could be accelerated if the research on aging and Parkinson's disease were planned together, and the perspective provided by gerontology gains relevance in this field.
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Affiliation(s)
- Manuel Rodriguez
- Laboratory of Neurobiology and Experimental Neurology, Department of Physiology, Faculty of Medicine, University of La LagunaLa Laguna, Spain
- Center for Networked Biomedical Research in Neurodegenerative Diseases (CIBERNED)La Laguna, Spain
| | - Clara Rodriguez-Sabate
- Center for Networked Biomedical Research in Neurodegenerative Diseases (CIBERNED)La Laguna, Spain
| | - Ingrid Morales
- Laboratory of Neurobiology and Experimental Neurology, Department of Physiology, Faculty of Medicine, University of La LagunaLa Laguna, Spain
- Center for Networked Biomedical Research in Neurodegenerative Diseases (CIBERNED)La Laguna, Spain
| | - Alberto Sanchez
- Laboratory of Neurobiology and Experimental Neurology, Department of Physiology, Faculty of Medicine, University of La LagunaLa Laguna, Spain
| | - Magdalena Sabate
- Rehabilitation Service, Department of Pharmacology and Physical Medicine, Faculty of Medicine, University of La LagunaLa Laguna, Spain
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23
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Rodriguez M, Morales I, Rodriguez-Sabate C, Sanchez A, Castro R, Brito JM, Sabate M. The degeneration and replacement of dopamine cells in Parkinson's disease: the role of aging. Front Neuroanat 2014; 8:80. [PMID: 25147507 PMCID: PMC4124707 DOI: 10.3389/fnana.2014.00080] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2014] [Accepted: 07/22/2014] [Indexed: 01/06/2023] Open
Abstract
Available data show marked similarities for the degeneration of dopamine cells in Parkinson’s disease (PD) and aging. The etio-pathogenic agents involved are very similar in both cases, and include free radicals, different mitochondrial disturbances, alterations of the mitophagy and the ubiquitin-proteasome system. Proteins involved in PD such as α-synuclein, UCH-L1, PINK1 or DJ-1, are also involved in aging. The anomalous behavior of astrocytes, microglia and stem cells of the subventricular zone (SVZ) also changes similarly in aging brains and PD. Present data suggest that PD could be the expression of aging on a cell population with high vulnerability to aging. The future knowledge of mechanisms involved in aging could be critical for both understanding the etiology of PD and developing etiologic treatments to prevent the onset of this neurodegenerative illness and to control its progression.
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Affiliation(s)
- Manuel Rodriguez
- Laboratory of Neurobiology and Experimental Neurology, Department of Physiology, Faculty of Medicine, University of La Laguna La Laguna, Tenerife, Canary Islands, Spain ; Center for Networked Biomedical Research in Neurodegenerative Diseases (CIBERNED) Madrid, Spain
| | - Ingrid Morales
- Laboratory of Neurobiology and Experimental Neurology, Department of Physiology, Faculty of Medicine, University of La Laguna La Laguna, Tenerife, Canary Islands, Spain ; Center for Networked Biomedical Research in Neurodegenerative Diseases (CIBERNED) Madrid, Spain
| | - Clara Rodriguez-Sabate
- Center for Networked Biomedical Research in Neurodegenerative Diseases (CIBERNED) Madrid, Spain
| | - Alberto Sanchez
- Laboratory of Neurobiology and Experimental Neurology, Department of Physiology, Faculty of Medicine, University of La Laguna La Laguna, Tenerife, Canary Islands, Spain
| | - Rafael Castro
- Laboratory of Neurobiology and Experimental Neurology, Department of Physiology, Faculty of Medicine, University of La Laguna La Laguna, Tenerife, Canary Islands, Spain
| | - Jose Miguel Brito
- Laboratory of Neurobiology and Experimental Neurology, Department of Physiology, Faculty of Medicine, University of La Laguna La Laguna, Tenerife, Canary Islands, Spain
| | - Magdalena Sabate
- Rehabilitation Service, Department of Physical Medicine and Pharmacology, Faculty of Medicine, University of La Laguna La Laguna, Tenerife, Canary Islands, Spain
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24
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Ye F, Samuels DC, Clark T, Guo Y. High-throughput sequencing in mitochondrial DNA research. Mitochondrion 2014; 17:157-63. [PMID: 24859348 PMCID: PMC4149223 DOI: 10.1016/j.mito.2014.05.004] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2014] [Revised: 04/04/2014] [Accepted: 05/13/2014] [Indexed: 12/14/2022]
Abstract
Next-generation sequencing, also known as high-throughput sequencing, has greatly enhanced researchers' ability to conduct biomedical research on all levels. Mitochondrial research has also benefitted greatly from high-throughput sequencing; sequencing technology now allows for screening of all 16,569 base pairs of the mitochondrial genome simultaneously for SNPs and low level heteroplasmy and, in some cases, the estimation of mitochondrial DNA copy number. It is important to realize the full potential of high-throughput sequencing for the advancement of mitochondrial research. To this end, we review how high-throughput sequencing has impacted mitochondrial research in the categories of SNPs, low level heteroplasmy, copy number, and structural variants. We also discuss the different types of mitochondrial DNA sequencing and their pros and cons. Based on previous studies conducted by various groups, we provide strategies for processing mitochondrial DNA sequencing data, including assembly, variant calling, and quality control.
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Affiliation(s)
- Fei Ye
- Department of Biostatistics, Vanderbilt University, Nashville, TN 37232, USA
| | - David C Samuels
- Center for Human Genetics, Vanderbilt University, Nashville, TN 37232, USA
| | - Travis Clark
- Vanderbilt Technology for Advanced Genomics, Vanderbilt University, Nashville, TN 37232, USA
| | - Yan Guo
- Department of Cancer Biology, Vanderbilt University, Nashville, TN 37232, USA
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25
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Cytoplasmic hybrid (cybrid) cell lines as a practical model for mitochondriopathies. Redox Biol 2014; 2:619-31. [PMID: 25460729 PMCID: PMC4297942 DOI: 10.1016/j.redox.2014.03.006] [Citation(s) in RCA: 91] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2014] [Accepted: 03/28/2014] [Indexed: 12/21/2022] Open
Abstract
Cytoplasmic hybrid (cybrid) cell lines can incorporate human subject mitochondria and perpetuate its mitochondrial DNA (mtDNA)-encoded components. Since the nuclear background of different cybrid lines can be kept constant, this technique allows investigators to study the influence of mtDNA on cell function. Prior use of cybrids has elucidated the contribution of mtDNA to a variety of biochemical parameters, including electron transport chain activities, bioenergetic fluxes, and free radical production. While the interpretation of data generated from cybrid cell lines has technical limitations, cybrids have contributed valuable insight into the relationship between mtDNA and phenotype alterations. This review discusses the creation of the cybrid technique and subsequent data obtained from cybrid applications. The cytoplasmic hybrid (cybrid) model can be used to determine mitochondrial DNA (mtDNA) contributions to phenotypic alterations. Cybrids are used to study mitochondriopathies such as Parkinson’s disease and Alzheimer’s disease. mtDNA heteroplasmy threshold and nuclear DNA-mtDNA compatibility can be determined using cybrid models.
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26
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Casoli T, Di Stefano G, Spazzafumo L, Balietti M, Giorgetti B, Giuli C, Postacchini D, Fattoretti P, Conti F. Contribution of non-reference alleles in mtDNA of Alzheimer's disease patients. Ann Clin Transl Neurol 2014; 1:284-9. [PMID: 25590040 PMCID: PMC4292745 DOI: 10.1002/acn3.42] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2013] [Revised: 12/20/2013] [Accepted: 01/20/2014] [Indexed: 12/01/2022] Open
Abstract
Many observations suggest that mutations of mitochondrial DNA (mtDNA) could be responsible for the neurodegenerative changes of Alzheimer's disease (AD). Here we examined the signal intensity of the four alleles of each mtDNA nucleotide position (np) in whole blood of AD patients and age-matched controls using MitoChip v2.0 array. Our analysis identified 270 significantly different nps which, with one exception, showed an increased contribution of non-reference alleles in AD patients. Principal component analysis (PCA) and cluster analysis showed that five of these nps could discriminate AD from control subjects with 80% of cases correctly classified. Our data support the hypothesis of mtDNA alterations as an important factor in the etiology of AD.
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Affiliation(s)
- Tiziana Casoli
- Center for Neurobiology of Aging, INRCA IRCCS Ancona, 60121, Italy
| | | | | | - Marta Balietti
- Cellular Bioenergetics Laboratory, Center for Neurobiology of Aging, INRCA IRCCS Ancona, 60121, Italy
| | | | - Cinzia Giuli
- Unit of Geriatrics, INRCA IRCCS Hospital Fermo, 63023, Italy
| | | | - Patrizia Fattoretti
- Cellular Bioenergetics Laboratory, Center for Neurobiology of Aging, INRCA IRCCS Ancona, 60121, Italy
| | - Fiorenzo Conti
- Center for Neurobiology of Aging, INRCA IRCCS Ancona, 60121, Italy ; Section of Neuroscience and Cell Biology, Department of Experimental and Clinical Medicine, Università Politecnica delle Marche Ancona, 60126, Italy
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Guo Y, Li CI, Sheng Q, Winther JF, Cai Q, Boice JD, Shyr Y. Very low-level heteroplasmy mtDNA variations are inherited in humans. J Genet Genomics 2013; 40:607-15. [PMID: 24377867 PMCID: PMC4149221 DOI: 10.1016/j.jgg.2013.10.003] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2013] [Revised: 10/24/2013] [Accepted: 10/27/2013] [Indexed: 01/18/2023]
Abstract
Little is known about the inheritance of very low heteroplasmy mitochondria DNA (mtDNA) variations. Even with the development of new next-generation sequencing methods, the practical lower limit of measured heteroplasmy is still about 1% due to the inherent noise level of the sequencing. In this study, we sequenced the mitochondrial genome of 44 individuals using Illumina high-throughput sequencing technology and obtained high-coverage mitochondria sequencing data. Our study population contains many mother-offspring pairs. This unique study design allows us to bypass the usual heteroplasmy limitation by analyzing the correlation of mutation levels at each position in the mtDNA sequence between maternally related pairs and non-related pairs. The study showed that very low heteroplasmy variants, down to almost 0.1%, are inherited maternally and that this inheritance begins to decrease at about 0.5%, corresponding to a bottleneck of about 200 mtDNA.
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Affiliation(s)
- Yan Guo
- Vanderbilt Ingram Cancer Center, Center for Quantitative Sciences, Nashville, TN 37232, USA.
| | - Chung-I Li
- Department of Applied Mathematics, Chiayi University (NCYU), Chiayi 60004, Taiwan, China
| | - Quanhu Sheng
- Vanderbilt Ingram Cancer Center, Center for Quantitative Sciences, Nashville, TN 37232, USA
| | - Jeanette F Winther
- Institute of Cancer Epidemiology, Danish Cancer Society, Copenhagen DK-2100, Denmark
| | - Qiuyin Cai
- Vanderbilt Epidemiology Center, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - John D Boice
- National Council on Radiation Protection & Measurements, Bethesda, MD 20814, USA
| | - Yu Shyr
- Vanderbilt Ingram Cancer Center, Center for Quantitative Sciences, Nashville, TN 37232, USA.
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28
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Thomas RR, Khan SM, Portell FR, Smigrodzki RM, Bennett JP. Recombinant human mitochondrial transcription factor A stimulates mitochondrial biogenesis and ATP synthesis, improves motor function after MPTP, reduces oxidative stress and increases survival after endotoxin. Mitochondrion 2010; 11:108-18. [PMID: 20727424 DOI: 10.1016/j.mito.2010.08.004] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2010] [Revised: 07/15/2010] [Accepted: 08/06/2010] [Indexed: 11/17/2022]
Abstract
Recombinant human mitochondrial transcription factor A protein (rhTFAM) was evaluated for its acute effects on cultured cells and chronic effects in mice. Fibroblasts incubated with rhTFAM acutely increased respiration in a chloramphenicol-sensitive manner. SH-SY5Y cells showed rhTFAM concentration-dependent reduction of methylpyridinium (MPP(+))-induced oxidative stress and increases in lowered ATP levels and viability. Mice treated with weekly i.v. rhTFAM showed increased mitochondrial gene copy number, complex I protein levels and ATP production rates; oxidative damage to proteins was decreased ~50%. rhTFAM treatment improved motor recovery rate after treatment with MPTP and dose-dependently improved survival in the lipopolysaccharide model of endotoxin sepsis.
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Affiliation(s)
- Ravindar R Thomas
- Morris Udall Parkinson's Disease Research Center of Excellence, University of Virginia, Charlottesville, VA, United States
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29
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Abstract
PURPOSE OF REVIEW To discuss novel developments related to the mechanisms of antiretroviral therapy-related mitochondrial toxicity, describe some apparent paradoxes in the current understanding of this field, and present questions that should be addressed by future research. RECENT FINDINGS The early polymerase gamma hypothesis states that nucleoside reverse transcriptase inhibitors can inhibit mitochondrial DNA replication and cause mitochondrial toxicity through mtDNA depletion. This mechanism is supported by a large body of evidence. Clinical manifestations of mitochondrial dysfunction are not always associated with mtDNA depletion. Increased mtDNA levels after nucleoside reverse transcriptase inhibitor exposure, as well as seemingly severe mtDNA depletion in individuals who show no clinical toxicity, have been reported. These and other observations suggest that additional mechanisms are involved in antiretroviral therapy toxicity, a notion supported by recent studies. Individuals given the same antiretroviral regimen can differ vastly with respect to the development of mitochondrial toxicity symptoms, reflecting interindividual variability. Some factors that may modulate this variability will be discussed. SUMMARY Mitochondrial toxicity induced by nucleoside reverse transcriptase inhibitors and their metabolic intermediates is probably mediated through many direct and indirect mechanisms. Depending on the mechanisms at play, the long-term health consequences of this toxicity may vary.
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30
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Keeney PM, Quigley CK, Dunham LD, Papageorge CM, Iyer S, Thomas RR, Schwarz KM, Trimmer PA, Khan SM, Portell FR, Bergquist KE, Bennett JP. Mitochondrial gene therapy augments mitochondrial physiology in a Parkinson's disease cell model. Hum Gene Ther 2009; 20:897-907. [PMID: 19374590 DOI: 10.1089/hum.2009.023] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Neurodegeneration in Parkinson's disease (PD) affects mainly dopaminergic neurons in the substantia nigra, where age-related, increasing percentages of cells lose detectable respiratory activity associated with depletion of intact mitochondrial DNA (mtDNA). Replenishment of mtDNA might improve neuronal bioenergetic function and prevent further cell death. We developed a technology ("ProtoFection") that uses recombinant human mitochondrial transcription factor A (TFAM) engineered with an N-terminal protein transduction domain (PTD) followed by the SOD2 mitochondrial localization signal (MLS) to deliver mtDNA cargo to the mitochondria of living cells. MTD-TFAM (MTD = PTD + MLS = "mitochondrial transduction domain") binds mtDNA and rapidly transports it across plasma membranes to mitochondria. For therapeutic proof-of-principle we tested ProtoFection technology in Parkinson's disease cybrid cells, using mtDNA generated from commercially available human genomic DNA (gDNA; Roche). Nine to 11 weeks after single exposures to MTD-TFAM + mtDNA complex, PD cybrid cells with impaired respiration and reduced mtDNA genes increased their mtDNA gene copy numbers up to 24-fold, mtDNA-derived RNAs up to 35-fold, TFAM and ETC proteins, cell respiration, and mitochondrial movement velocities. Cybrid cells with no or minimal basal mitochondrial impairments showed reduced or no responses to treatment, suggesting the possibility of therapeutic selectivity. Exposure of PD but not control cybrid cells to MTD-TFAM protein alone or MTD-TFAM + mtDNA complex increased expression of PGC-1alpha, suggesting activation of mitochondrial biogenesis. ProtoFection technology for mitochondrial gene therapy holds promise for improving bioenergetic function in impaired PD neurons and needs additional development to define its pharmacodynamics and delineate its molecular mechanisms. It also is unclear whether single-donor gDNA for generating mtDNA would be a preferred therapeutic compared with the pooled gDNA used in this study.
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Affiliation(s)
- Paula M Keeney
- Morris K. Udall Parkinson's Disease Research Center of Excellence, University of Virginia, Charlottesville, VA 22908, USA
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31
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Keeney PM, Dunham LD, Quigley CK, Morton SL, Bergquist KE, Bennett JP. Cybrid models of Parkinson's disease show variable mitochondrial biogenesis and genotype-respiration relationships. Exp Neurol 2009; 220:374-82. [PMID: 19815014 DOI: 10.1016/j.expneurol.2009.09.025] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2009] [Revised: 09/23/2009] [Accepted: 09/28/2009] [Indexed: 01/01/2023]
Abstract
Sporadic Parkinson's disease (sPD) is a nervous system-wide disease that presents with a bradykinetic movement disorder and frequently progresses to include depression and cognitive impairment. Cybrid models of sPD are based on expression of sPD platelet mitochondrial DNA (mtDNA) in neural cells and demonstrate some similarities to sPD brains. In sPD and CTL cybrids we characterized aspects of mitochondrial biogenesis, mtDNA genomics, composition of the respirasome and the relationships among isolated mitochondrial and intact cell respiration. Cybrid mtDNA levels varied and correlated with expression of PGC-1 alpha, a transcriptional co-activator regulator of mitochondrial biogenesis. Levels of mtDNA heteroplasmic mutations were asymmetrically distributed across the mitochondrial genome; numbers of heteroplasmies were more evenly distributed. Neither levels nor numbers of heteroplasmies distinguished sPD from CTL. sPD cybrid mitochondrial ETC subunit protein levels were not altered. Isolated mitochondrial complex I respiration rates showed limited correlation with whole cell complex I respiration rates in both sPD and CTL cybrids. Intact cell respiration during the normoxic-anoxic transition yielded K(m) values for oxygen that directly related to respiration rates in CTL but not in sPD cell lines. Both sPD and CTL cybrid cells are substantially heterogeneous in mitochondrial genomic and physiologic properties. Our results suggest that mtDNA depletion may occur in sPD neurons and could reflect impairment of mitochondrial biogenesis. Cybrids remain a valuable model for some aspects of sPD but their heterogeneity mitigates against a simple designation of sPD phenotype in this cell model.
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Affiliation(s)
- Paula M Keeney
- Morris K. Udall Parkinson's Research Center of Excellence, University of Virginia, PO Box 800394, Charlottesville, VA 22908, USA
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32
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Jones TT, Brewer GJ. Age-related deficiencies in complex I endogenous substrate availability and reserve capacity of complex IV in cortical neuron electron transport. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2009; 1797:167-76. [PMID: 19799853 DOI: 10.1016/j.bbabio.2009.09.009] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2009] [Revised: 09/22/2009] [Accepted: 09/24/2009] [Indexed: 10/20/2022]
Abstract
Respiratory enzyme complex dysfunction is mechanistically involved in mitochondrial failure leading to neurodegenerative disease, but the pathway is unclear. Here, age-related differences in mitochondrial respiration were measured in both whole and permeabilized neurons from 9-month and 24-month adult rat cortex cultured in common conditions. After permeabilization, respiration increased in both ages of neurons with excess substrates. To dissect specific deficiencies in the respiratory chain, inhibitors for each respiratory chain complex were used to isolate their contributions. Relative to neurons from 9-month rats, in neurons isolated from 24-month rats, complexes I, III, and IV were more sensitive to selective inhibition. Flux control point analysis identified complex I in neurons isolated from 24-month rats as the most sensitive to endogenous substrate availability. The greatest age-related deficit in flux capacity occurred at complex IV with a 29% decrease in neurons isolated from 24-month rats relative to those from 9-month rats. The deficits in complexes I and III may contribute to a redox shift in the quinone pool within the electron transport chain, further extending these age-related deficits. Together these changes could lead to an age-related catastrophic decline in energy production and neuronal death.
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Affiliation(s)
- Torrie T Jones
- Department of Medical Microbiology, Immunology, and Cell Biology, Southern Illinois University School of Medicine, PO Box 19626, Springfield, IL 62794-9626, USA
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33
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Wright AF, Murphy MP, Turnbull DM. Do organellar genomes function as long-term redox damage sensors? Trends Genet 2009; 25:253-61. [PMID: 19481287 DOI: 10.1016/j.tig.2009.04.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2009] [Revised: 04/06/2009] [Accepted: 04/08/2009] [Indexed: 12/31/2022]
Abstract
A small group of proteins that form core components of electron transfer complexes are consistently encoded by organellar genomes in multicellular organisms, suggesting functional constraint. These genomes are costly to maintain and vulnerable to mutation. We propose that they provide cell lineages with sensors of long-term redox damage, and of bioenergetic and genomic competence. This proposed adaptive function sets tonic retrograde signalling to the nucleus and anterograde responses influencing protective and cell death pathways. The nature of the proposed gain-of-function signalling mechanisms is unclear but could involve defective complex assembly. Organellar proteomes therefore provide cumulative feedback on bioenergetic and genomic status within cell lineages, selection of the energetically 'fittest' cells and a means of removing cells that compromise survival of the organism.
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Affiliation(s)
- Alan F Wright
- Medical Research Council Human Genetics Unit, Institute of Genetics and Molecular Medicine, Edinburgh EH4 2XU, UK.
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34
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Dubec SJ, Aurora R, Zassenhaus HP. Mitochondrial DNA mutations may contribute to aging via cell death caused by peptides that induce cytochrome c release. Rejuvenation Res 2008; 11:611-9. [PMID: 18593279 DOI: 10.1089/rej.2007.0617] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Mice wherein the wild-type mitochondrial DNA polymerase (pol gamma) is replaced by a proofreading-deficient version are born with mutation frequencies in mitochondrial DNA (mtDNA) much higher than are ever normally seen in old rodents or humans. These mice, however, are phenotypically normal at birth, raising the question regarding how the much lower frequencies observed in normal aging could possibly contribute to the aging process. In contrast, transgenic mice with cardiac-specific expression of a proofreading-deficient poly gamma from birth onwards accumulate mtDNA mutations to levels normally seen in aging. But these mice develop dilated cardiomyopathy suggesting that age-related mtDNA mutations are pathogenic. Using computer simulation, we show that both findings are predicted based on the hypotheses that (1) rare lethal mutations that cause apoptosis underlie the pathogenesis of mutagenesis in mtDNA and (2) most sporadic mtDNA mutations are phenotypically recessive and therefore nonpathogenic. Biochemical evidence is presented that mitochondria with mtDNA mutations generate a peptide that causes the release of cytochrome c, providing a mechanism for the increased apoptosis observed in aging. Simulation also predicts that normal, age-related accumulation of mtDNA mutations causes significant levels of cell death. These findings suggest that mtDNA mutations play an important role in the aging process and that their pathogenic mechanism is linked to apoptosis.
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Affiliation(s)
- Steven J Dubec
- Department of Molecular Microbiology and Immunology, St Louis University School of Medicine, St Louis, MO 63104, USA
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35
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Reed KM. Using mtDNA sequences to estimate SNP parameters in ESTs. Anim Biotechnol 2008; 19:166-77. [PMID: 18607789 DOI: 10.1080/10495390802170916] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Discovery of single nucleotide polymorphisms (SNPs) requires analysis of redundant sequences such as those available in large public databases. The ability to detect SNPs, especially those of low frequency, is dependent on the depth and scale of the discovery effort. Large numbers of SNPs have been identified by mining large-scale EST surveys and whole genome sequencing projects. These surveys however are subject to ascertainment bias and the inherent errors in large-scale single pass sequencing efforts. For example, the number of steps involved in the construction and sequencing of cDNA libraries make ESTs highly error prone, resulting in an increased frequency of nonvalid SNPs obtained in these surveys. Sequences of mtDNA genes are often incorporated into cDNA libraries as an artifact of the library construction process and are typically either subtracted from cDNA libraries or are considered superfluous when evaluating the information content of EST datasets. Sequences of mtDNA genes provide a unique resource for the analysis of SNP parameters in EST projects. This study uses sequences from four turkey muscle cDNA libraries to demonstrate how mtDNA sequences gleaned from collections of ESTs can be used to estimate SNP parameters and thus help predict the validity of SNPs.
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Affiliation(s)
- Kent M Reed
- Department of Veterinary and Biomedical Sciences, College of Veterinary Medicine, University of Minnesota, St. Paul, Minnesota 55108, USA.
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36
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Swerdlow RH. Mitochondria in cybrids containing mtDNA from persons with mitochondriopathies. J Neurosci Res 2008; 85:3416-28. [PMID: 17243174 DOI: 10.1002/jnr.21167] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The cytoplasmic hybrid (cybrid) technique allows investigators to express selected mitochondrial DNA (mtDNA) sequences against fixed nuclear DNA (nDNA) backgrounds. Cybrids have been used to study the effects of known mtDNA mutations on mitochondrial biochemistry, mtDNA-nDNA inter-species compatibility, and mtDNA integrity in persons without mtDNA mutations defined previously. This review discusses events leading up to creation of the cybrid technique, as well as data obtained via application of the cybrid strategies listed above. Although interpreting cybrid data requires awareness of technique limitations, valuable insights into mtDNA genotype-functional phenotype relationships are suggested.
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Affiliation(s)
- Russell H Swerdlow
- Department of Neurology, University of Virginia School of Medicine, Charlottesville, VA 22908, USA.
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37
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Oxidative stress caused by blocking of mitochondrial complex I H(+) pumping as a link in aging/disease vicious cycle. Int J Biochem Cell Biol 2008; 40:1792-805. [PMID: 18291703 DOI: 10.1016/j.biocel.2008.01.012] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2007] [Revised: 01/14/2008] [Accepted: 01/14/2008] [Indexed: 12/16/2022]
Abstract
Vulnerability of mitochondrial Complex I to oxidative stress determines an organism's lifespan, pace of aging, susceptibility to numerous diseases originating from oxidative stress and certain mitopathies. The mechanisms involved, however, are largely unknown. We used confocal microscopy and fluorescent probe MitoSOX to monitor superoxide production due to retarded forward electron transport in HEPG2 cell mitochondrial Complex I in situ. Matrix-released superoxide production, the un-dismuted surplus (J(m)) was low in glucose-cultivated cells, where an uncoupler (FCCP) reduced it to half. Rotenone caused a 5-fold J(m) increase (AC(50) 2 microM), which was attenuated by uncoupling, membrane potential (DeltaPsi(m)), and DeltapH-collapse, since addition of FCCP (IC(50) 55 nM), valinomycin, and nigericin prevented this increase. J(m) doubled after cultivation with galactose/glutamine (i.e. at obligatory oxidative phosphorylation). A hydrophobic amiloride that acts on the ND5 subunit and inhibits Complex I H(+) pumping enhanced J(m) and even countered the FCCP effect (AC(50) 0.3 microM). Consequently, we have revealed a new principle predicting that Complex I produces maximum superoxide only when both electron transport and H(+) pumping are retarded. H(+) pumping may be attenuated by high protonmotive force or inhibited by oxidative stress-related mutations of ND5 (ND2, ND4) subunit. We predict that in a vicious cycle, when oxidative stress leads to higher fraction of, e.g. mutated ND5 subunits, it will be accelerated more and more. Thus, inhibition of Complex I H(+) pumping, which leads to oxidative stress, appears to be a missing link in the theory of mitochondrial aging and in the etiology of diseases related to oxidative stress.
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38
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Prokopov AF. Theoretical Paper:Exploring Overlooked Natural Mitochondria-Rejuvenative Intervention: The Puzzle of Bowhead Whales and Naked Mole Rats. Rejuvenation Res 2007; 10:543-60. [DOI: 10.1089/rej.2007.0546] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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39
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Swerdlow RH. Treating neurodegeneration by modifying mitochondria: potential solutions to a "complex" problem. Antioxid Redox Signal 2007; 9:1591-603. [PMID: 17663643 DOI: 10.1089/ars.2007.1676] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Mitochondria function differently in aged brains than they do in young brains. Consistently reported changes include reduced electron transport chain (ETC) enzyme activities, reduced phosphorylation of ADP, and increased reactive oxygen species (ROS) production. Various neurodegenerative diseases are also associated with changes in mitochondrial function, and these changes both recapitulate and extend those seen in "normal" aging. Unfortunately, attempts to treat neurodegenerative diseases by treating mitochondria-related pathology have thus far minimally impacted affected patients. A better understanding of how mitochondrial function changes in aging and neurodegenerative diseases, though, now suggests new approaches to mitochondrial therapy may prove more efficacious. Increasing ETC capacity, increasing oxidative phosphorylation, or decreasing mitochondrial ROS may yet prove useful for the treatment of brain aging and neurodegenerative diseases, and accomplishing this seems increasingly feasible. This review will discuss the role of mitochondrial function and dysfunction in aging and neurodegenerative diseases, and will focus on potential treatment strategies.
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Affiliation(s)
- Russell H Swerdlow
- Department of Neurology, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA.
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40
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Verma M, Kumar D. Application of mitochondrial genome information in cancer epidemiology. Clin Chim Acta 2007; 383:41-50. [PMID: 17532310 DOI: 10.1016/j.cca.2007.04.018] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2007] [Revised: 04/02/2007] [Accepted: 04/07/2007] [Indexed: 12/18/2022]
Abstract
Two genomes, nuclear and mitochondrial, exist in humans although information contained in the mitochondrial genome has not been fully utilized in cancer epidemiology. Over the last few years, a variety of approaches have been developed to improve results of conventional cancer screening by detecting molecular markers in different populations. Mitochondrial DNA alterations (mutations, deletions and instability) are emerging as new molecular markers for detecting a variety of cancers in tissue samples and biofluids which can be included in population screening studies. Since mitochondrial genome is small (16.6 kb) and high-throughput assays have been developed for sequencing whole mitochondrial genome, it can be adopted by most of the laboratories conducting epidemiological studies. Applications of mitochondrial DNA markers to identify high risk populations and future challenges are discussed in this article.
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Affiliation(s)
- Mukesh Verma
- Analytic Epidemiology Research Branch, Epidemiology and Genetics Research Program, Division of Cancer Control and Population Sciences, National Cancer Institute, Rockville, MD 20852, USA.
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43
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Khan SM, Smigrodzki RM, Swerdlow RH. Cell and animal models of mtDNA biology: progress and prospects. Am J Physiol Cell Physiol 2006; 292:C658-69. [PMID: 16899549 DOI: 10.1152/ajpcell.00224.2006] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The past two decades have witnessed an evolving understanding of the mitochondrial genome's (mtDNA) role in basic biology and disease. From the recognition that mutations in mtDNA can be responsible for human disease to recent efforts showing that mtDNA mutations accumulate over time and may be responsible for some phenotypes of aging, the field of mitochondrial genetics has greatly benefited from the creation of cell and animal models of mtDNA mutation. In this review, we critically discuss the past two decades of efforts and insights gained from cell and animal models of mtDNA mutation. We attempt to reconcile the varied and at times contradictory findings by highlighting the various methodologies employed and using human mtDNA disease as a guide to better understanding of cell and animal mtDNA models. We end with a discussion of scientific and therapeutic challenges and prospects for the future of mtDNA transfection and gene therapy.
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Affiliation(s)
- Shaharyar M Khan
- Gencia Corp., 706 B Forrest St., Charlottesville, VA 22903, USA.
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44
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Mott JL, Zhang D, Zassenhaus HP. Mitochondrial DNA Mutations, Apoptosis, and the Misfolded Protein Response. Rejuvenation Res 2005; 8:216-26. [PMID: 16313221 DOI: 10.1089/rej.2005.8.216] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Studies of transgenic mice with accelerated accumulation of mtDNA mutations specifically in the heart lead us to propose that apoptotic signaling and cell death is central to the pathogenesis of mtDNA mutations in aging. It is the cellular response to that apoptotic signaling and the organ?s compensatory response to a loss of cells that specify the phenotype of an accumulation of mtDNA mutations. In the heart, cardiomyocytes induce a vigorous anti-apoptotic, pro-survival response to counteract mitochondrial apoptotic signaling. The heart up-regulates contractility of remaining myocytes in order to maintain cardiac output. We hypothesize that mutant mitochondrial proteins originate apoptotic signaling by interacting with proteins already in place in the mitochondrial outer membrane that regulate apoptosis, for example the pro-apoptotic protein Bak. Since it is unlikely that all mutant mitochondrial proteins have the necessary structure and localization within the inner membrane to activate Bak appropriately, only a small fraction of an age-associated burden of mtDNA mutations may be pathogenic. In this model, reactive oxygen species generated by mitochondrial respiration drive the formation of mtDNA mutations, but are not the primary mechanism for their pathogenicity.
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Affiliation(s)
- Justin L Mott
- Department of Molecular Microbiology and Immunology, St. Louis University Health Science Center, Missouri, USA
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