301
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D'Erchia AM, Atlante A, Gadaleta G, Pavesi G, Chiara M, De Virgilio C, Manzari C, Mastropasqua F, Prazzoli GM, Picardi E, Gissi C, Horner D, Reyes A, Sbisà E, Tullo A, Pesole G. Tissue-specific mtDNA abundance from exome data and its correlation with mitochondrial transcription, mass and respiratory activity. Mitochondrion 2014; 20:13-21. [PMID: 25446395 DOI: 10.1016/j.mito.2014.10.005] [Citation(s) in RCA: 121] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2014] [Revised: 09/23/2014] [Accepted: 10/29/2014] [Indexed: 01/12/2023]
Abstract
Eukaryotic cells contain a population of mitochondria, variable in number and shape, which in turn contain multiple copies of a tiny compact genome (mtDNA) whose expression and function is strictly coordinated with the nuclear one. mtDNA copy number varies between different cell or tissues types, both in response to overall metabolic and bioenergetics demands and as a consequence or cause of specific pathological conditions. Here we present a novel and reliable methodology to assess the effective mtDNA copy number per diploid genome by investigating off-target reads obtained by whole-exome sequencing (WES) experiments. We also investigate whether and how mtDNA copy number correlates with mitochondrial mass, respiratory activity and expression levels. Analyzing six different tissues from three age- and sex-matched human individuals, we found a highly significant linear correlation between mtDNA copy number estimated by qPCR and the frequency of mtDNA off target WES reads. Furthermore, mtDNA copy number showed highly significant correlation with mitochondrial gene expression levels as measured by RNA-Seq as well as with mitochondrial mass and respiratory activity. Our methodology makes thus feasible, at a large scale, the investigation of mtDNA copy number in diverse cell-types, tissues and pathological conditions or in response to specific treatments.
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Affiliation(s)
- Anna Maria D'Erchia
- Dipartimento di Bioscienze, Biotecnologie e Biofarmaceutica, Università degli Studi di Bari Aldo Moro, Via Orabona 4, Bari 70126, Italy
| | - Anna Atlante
- Istituto di Biomembrane e Bioenergetica, CNR, via Amendola 165/A, Bari 70126, Italy
| | - Gemma Gadaleta
- Dipartimento di Bioscienze, Biotecnologie e Biofarmaceutica, Università degli Studi di Bari Aldo Moro, Via Orabona 4, Bari 70126, Italy
| | - Giulio Pavesi
- Dipartimento di Bioscienze, Università degli Studi di Milano, Via Celoria 26, Milano 20133, Italy
| | - Matteo Chiara
- Dipartimento di Bioscienze, Università degli Studi di Milano, Via Celoria 26, Milano 20133, Italy
| | - Caterina De Virgilio
- Dipartimento di Bioscienze, Biotecnologie e Biofarmaceutica, Università degli Studi di Bari Aldo Moro, Via Orabona 4, Bari 70126, Italy
| | - Caterina Manzari
- Istituto di Biomembrane e Bioenergetica, CNR, via Amendola 165/A, Bari 70126, Italy
| | - Francesca Mastropasqua
- Dipartimento di Bioscienze, Biotecnologie e Biofarmaceutica, Università degli Studi di Bari Aldo Moro, Via Orabona 4, Bari 70126, Italy
| | - Gian Marco Prazzoli
- Dipartimento di Bioscienze, Università degli Studi di Milano, Via Celoria 26, Milano 20133, Italy
| | - Ernesto Picardi
- Dipartimento di Bioscienze, Biotecnologie e Biofarmaceutica, Università degli Studi di Bari Aldo Moro, Via Orabona 4, Bari 70126, Italy
| | - Carmela Gissi
- Dipartimento di Bioscienze, Università degli Studi di Milano, Via Celoria 26, Milano 20133, Italy
| | - David Horner
- Dipartimento di Bioscienze, Università degli Studi di Milano, Via Celoria 26, Milano 20133, Italy
| | - Aurelio Reyes
- Mitochondrial Biology Unit, Medical Research Council, Wellcome Trust/MRC Building, Hills Road, Cambridge CB2 0XY, United Kingdom
| | - Elisabetta Sbisà
- Istituto di Tecnologie Biomediche- Sede di Bari, CNR, Via Amendola 122/D, Bari 70126, Italy
| | - Apollonia Tullo
- Istituto di Tecnologie Biomediche- Sede di Bari, CNR, Via Amendola 122/D, Bari 70126, Italy
| | - Graziano Pesole
- Dipartimento di Bioscienze, Biotecnologie e Biofarmaceutica, Università degli Studi di Bari Aldo Moro, Via Orabona 4, Bari 70126, Italy; Istituto di Biomembrane e Bioenergetica, CNR, via Amendola 165/A, Bari 70126, Italy.
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302
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Xu Y, Lu S. Transforming growth factor-β1-induced epithelial to mesenchymal transition increases mitochondrial content in the A549 non-small cell lung cancer cell line. Mol Med Rep 2014; 11:417-21. [PMID: 25323156 DOI: 10.3892/mmr.2014.2678] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2012] [Accepted: 07/30/2014] [Indexed: 11/06/2022] Open
Abstract
The mitochondrial genome DNA copy number is critical for the functional maintenance of the mitochondria and energy acquisition for cell metabolism. Epithelial to mesenchymal transition (EMT) is an important process during embryonic development and has also been hypothesized to exhibit a significant role in cancer cell invasion and metastasis. In the present study, EMT was induced in the A549 non-small cell lung cancer (NSCLC) cell line, using transforming growth factor-β1 (TGF-β1) and changes in mitochondrial content, mitochondrial DNA (mtDNA) copy number and protein cytochrome c (Cyt c) were determined by reverse transcription-quantitative polymerase chain reaction and western blot analysis, respectively. mtDNA copy number and Cyt c protein levels were observed to increase following the induction of EMT in NSCLC cells. Results of the current study indicate that energy metabolism is adapted to facilitate EMT in NSCLC cells.
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Affiliation(s)
- Yunhua Xu
- Shanghai Lung Cancer Center, Shanghai Chest Hospital, Shanghai Jiaotong University, Shanghai 200030, P.R. China
| | - Shun Lu
- Shanghai Lung Cancer Center, Shanghai Chest Hospital, Shanghai Jiaotong University, Shanghai 200030, P.R. China
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303
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Mozhey OI, Zatolokin PA, Vasilenko MA, Litvinova LS, Kirienkova EV, Mazunin IO. Evaluating the number of mitochondrial DNA copies in leukocytes and adipocytes from metabolic syndrome patients: Pilot study. Mol Biol 2014. [DOI: 10.1134/s0026893314040074] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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304
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de Sousa RT, Machado-Vieira R, Zarate CA, Manji HK. Targeting mitochondrially mediated plasticity to develop improved therapeutics for bipolar disorder. Expert Opin Ther Targets 2014; 18:1131-47. [PMID: 25056514 DOI: 10.1517/14728222.2014.940893] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
INTRODUCTION Bipolar disorder (BPD) is a severe illness with few treatments available. Understanding BPD pathophysiology and identifying potential relevant targets could prove useful for developing new treatments. Remarkably, subtle impairments of mitochondrial function may play an important role in BPD pathophysiology. AREAS COVERED This article focuses on human studies and reviews evidence of mitochondrial dysfunction in BPD as a promising target for the development of new, improved treatments. Mitochondria are crucial for energy production, generated mainly through the electron transport chain (ETC) and play an important role in regulating apoptosis and calcium (Ca²⁺) signaling as well as synaptic plasticity. Mitochondria move throughout the neurons to provide energy for intracellular signaling. Studies showed polymorphisms of mitochondria-related genes as risk factors for BPD. Postmortem studies in BPD also show decreased ETC activity/expression and increased nitrosative and oxidative stress (OxS) in patient brains. BPD has been also associated with increased OxS, Ca²⁺ dysregulation and increased proapoptotic signaling in peripheral blood. Neuroimaging studies consistently show decreased energy levels and pH in brains of BPD patients. EXPERT OPINION Targeting mitochondrial function, and their role in energy metabolism, synaptic plasticity and cell survival, may be an important avenue for development of new mood-stabilizing agents.
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Affiliation(s)
- Rafael T de Sousa
- University of Sao Paulo, Institute and Department of Psychiatry, Laboratory of Neuroscience, LIM-27, Faculty of Medicine , Paulo Rua Ovidio Pires de Campos 785, São Paulo, SP , Brazil
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305
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Mitochondrial function and mitochondrial DNA maintenance with advancing age. Biogerontology 2014; 15:417-38. [PMID: 25015781 DOI: 10.1007/s10522-014-9515-2] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2014] [Accepted: 07/01/2014] [Indexed: 12/24/2022]
Abstract
We review the impact of mitochondrial DNA (mtDNA) maintenance and mitochondrial function on the aging process. Mitochondrial function and mtDNA integrity are closely related. In order to create a protective barrier against reactive oxygen and nitrogen species (RONS) attacks and ensure mtDNA integrity, multiple cellular mtDNA copies are packaged together with various proteins in nucleoids. Regulation of antioxidant and RONS balance, DNA base excision repair, and selective degradation of damaged mtDNA copies preserves normal mtDNA quantities. Oxidative damage to mtDNA molecules does not substantially contribute to increased mtDNA mutation frequency; rather, mtDNA replication errors of DNA PolG are the main source of mtDNA mutations. Mitochondrial turnover is the major contributor to maintenance of mtDNA and functionally active mitochondria. Mitochondrial turnover involves mitochondrial biogenesis, mitochondrial dynamics, and selective autophagic removal of dysfunctional mitochondria (i.e., mitophagy). All of these processes exhibit decreased activity during aging and fall under greater nuclear genome control, possibly coincident with the emergence of nuclear genome instability. We suggest that the age-dependent accumulation of mutated mtDNA copies and dysfunctional mitochondria is associated primarily with decreased cellular autophagic and mitophagic activity.
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306
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Ridge PG, Maxwell TJ, Foutz SJ, Bailey MH, Corcoran CD, Tschanz JT, Norton MC, Munger RG, O'Brien E, Kerber RA, Cawthon RM, Kauwe JSK. Mitochondrial genomic variation associated with higher mitochondrial copy number: the Cache County Study on Memory Health and Aging. BMC Bioinformatics 2014; 15 Suppl 7:S6. [PMID: 25077862 PMCID: PMC4110732 DOI: 10.1186/1471-2105-15-s7-s6] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Background The mitochondria are essential organelles and are the location of cellular respiration, which is responsible for the majority of ATP production. Each cell contains multiple mitochondria, and each mitochondrion contains multiple copies of its own circular genome. The ratio of mitochondrial genomes to nuclear genomes is referred to as mitochondrial copy number. Decreases in mitochondrial copy number are known to occur in many tissues as people age, and in certain diseases. The regulation of mitochondrial copy number by nuclear genes has been studied extensively. While mitochondrial variation has been associated with longevity and some of the diseases known to have reduced mitochondrial copy number, the role that the mitochondrial genome itself has in regulating mitochondrial copy number remains poorly understood. Results We analyzed the complete mitochondrial genomes from 1007 individuals randomly selected from the Cache County Study on Memory Health and Aging utilizing the inferred evolutionary history of the mitochondrial haplotypes present in our dataset to identify sequence variation and mitochondrial haplotypes associated with changes in mitochondrial copy number. Three variants belonging to mitochondrial haplogroups U5A1 and T2 were significantly associated with higher mitochondrial copy number in our dataset. Conclusions We identified three variants associated with higher mitochondrial copy number and suggest several hypotheses for how these variants influence mitochondrial copy number by interacting with known regulators of mitochondrial copy number. Our results are the first to report sequence variation in the mitochondrial genome that causes changes in mitochondrial copy number. The identification of these variants that increase mtDNA copy number has important implications in understanding the pathological processes that underlie these phenotypes.
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307
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Li Y, Huang W, Yu Q, Cheng YT, Kong QP. Lower mitochondrial DNA content relates to high-altitude adaptation in Tibetans. ACTA ACUST UNITED AC 2014; 27:753-7. [DOI: 10.3109/19401736.2014.915526] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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308
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Petersen MH, Budtz-Jørgensen E, Sørensen SA, Nielsen JE, Hjermind LE, Vinther-Jensen T, Nielsen SMB, Nørremølle A. Reduction in mitochondrial DNA copy number in peripheral leukocytes after onset of Huntington's disease. Mitochondrion 2014; 17:14-21. [PMID: 24836434 DOI: 10.1016/j.mito.2014.05.001] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Revised: 04/03/2014] [Accepted: 05/06/2014] [Indexed: 01/14/2023]
Abstract
Huntington's disease (HD) is an inherited neurodegenerative disorder characterised by movement disorder, cognitive symptoms and psychiatric symptoms with predominantly adult-onset. The mutant huntingtin protein leads to mitochondrial dysfunction in blood leukocytes. This discovery led to the investigation of the mitochondrial DNA (mtDNA) copy number relative to nuclear DNA (nDNA) in leukocytes from carriers of the HD mutation compared to healthy individuals. We found significantly reduced mtDNA/nDNA in HD mutation carriers compared to controls. A longitudinal study of archive DNA sample pairs from HD patients revealed a biphasic pattern of increasing mtDNA/nDNA before onset of motor symptoms and decreasing mtDNA/nDNA after.
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Affiliation(s)
- Maria Hvidberg Petersen
- Department of Cellular and Molecular Medicine, University of Copenhagen, Panum Institute, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark
| | - Esben Budtz-Jørgensen
- Department of Cellular and Molecular Medicine, University of Copenhagen, Panum Institute, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark
| | - Sven Asger Sørensen
- Department of Cellular and Molecular Medicine, University of Copenhagen, Panum Institute, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark
| | - Jørgen Erik Nielsen
- Department of Cellular and Molecular Medicine, University of Copenhagen, Panum Institute, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark; Neurogenetics Clinic, Danish Dementia Research Centre, Department of Neurology, Rigshospitalet, University of Copenhagen, Blegdamsvej 9, DK-2100 Copenhagen Ø, Denmark
| | - Lena Elisabeth Hjermind
- Department of Cellular and Molecular Medicine, University of Copenhagen, Panum Institute, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark; Neurogenetics Clinic, Danish Dementia Research Centre, Department of Neurology, Rigshospitalet, University of Copenhagen, Blegdamsvej 9, DK-2100 Copenhagen Ø, Denmark
| | - Tua Vinther-Jensen
- Department of Cellular and Molecular Medicine, University of Copenhagen, Panum Institute, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark; Neurogenetics Clinic, Danish Dementia Research Centre, Department of Neurology, Rigshospitalet, University of Copenhagen, Blegdamsvej 9, DK-2100 Copenhagen Ø, Denmark
| | - Signe Marie Borch Nielsen
- Department of Cellular and Molecular Medicine, University of Copenhagen, Panum Institute, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark
| | - Anne Nørremølle
- Department of Cellular and Molecular Medicine, University of Copenhagen, Panum Institute, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark.
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309
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He Y, Tang J, Li Z, Li H, Liao Y, Tang Y, Tan L, Chen J, Xia K, Chen X. Leukocyte mitochondrial DNA copy number in blood is not associated with major depressive disorder in young adults. PLoS One 2014; 9:e96869. [PMID: 24809340 PMCID: PMC4014566 DOI: 10.1371/journal.pone.0096869] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2013] [Accepted: 04/12/2014] [Indexed: 01/02/2023] Open
Abstract
Background Major depressive disorder (MDD) is the leading cause of disability worldwide, and has significant genetic predisposition. Mitochondria may have a role in MDD and so mitochondrial DNA (mtDNA) has been suggested as a possible biomarker for this disease. We aimed to test whether the mtDNA copy number of peripheral blood leukocytes is related to MDD in young adults. Methods A case-control study was conducted with 210 MDD patients and 217 healthy controls (HC). The mtDNA copy number was measured by quantitative polymerase chain reaction (qPCR) method. Depression severity was assessed by the Hamilton-17 Depression Rating Scale (HDRS-17). Results We found no significant differences in mtDNA copy number between MDD patients and HC, though the power analysis showed that our sample size has enough power to detect the difference. There were also no significant correlations between mtDNA copy number and the clinical characteristics (such as age, age of onset, episodes, Hamilton Depression Rating Scale (HDRS) score and Global Assessment of Function Scale (GAF) score) in MDD patients. Conclusion Our study suggests that leukocyte mtDNA copy number is unlikely to contribute to MDD, but it doesn’t mean that we can exclude the possibility of involvement of mitochondria in the disease. Further studies are required to elucidate whether mtDNA can be a biomarker of MDD.
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Affiliation(s)
- Ying He
- Institute of Mental Health, the Second Xiangya Hospital of Central South University, Changsha, Hunan, China
| | - Jinsong Tang
- Institute of Mental Health, the Second Xiangya Hospital of Central South University, Changsha, Hunan, China
| | - Zongchang Li
- Institute of Genomic Medicine, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Hong Li
- Institute of Mental Health, the Second Xiangya Hospital of Central South University, Changsha, Hunan, China
| | - Yanhui Liao
- Institute of Mental Health, the Second Xiangya Hospital of Central South University, Changsha, Hunan, China
| | - Yanqing Tang
- Department of Psychiatry, First Affiliated Hospital, China Medical University, Shenyang, Liaoning, China
| | - Liwen Tan
- Institute of Mental Health, the Second Xiangya Hospital of Central South University, Changsha, Hunan, China
| | - Jindong Chen
- Institute of Mental Health, the Second Xiangya Hospital of Central South University, Changsha, Hunan, China
| | - Kun Xia
- The State Key Laboratory of Medical Genetics, Central South University, Changsha, Hunan, China
| | - Xiaogang Chen
- Institute of Mental Health, the Second Xiangya Hospital of Central South University, Changsha, Hunan, China; The State Key Laboratory of Medical Genetics, Central South University, Changsha, Hunan, China; Key Laboratory of Psychiatry and Mental Health of Hunan Province, Central South University, Changsha, Hunan, China; The State Key Laboratory of Medical Genetics, Central South University, Changsha, Hunan, China
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310
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He Y, Gong Y, Gu J, Lee JJ, Lippman SM, Wu X. Increased leukocyte mitochondrial DNA copy number is associated with oral premalignant lesions: an epidemiology study. Carcinogenesis 2014; 35:1760-4. [PMID: 24743515 DOI: 10.1093/carcin/bgu093] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Although changes in the mitochondrial DNA (mtDNA) copy number in peripheral blood leukocytes (PBLs) have been linked to increased susceptibility to several cancers, the relationship between the mtDNA copy number in PBLs and the risk of cancer precursors has not been investigated. In this study, we measured the relative mtDNA copy number in PBLs of 143 patients with histologically confirmed oral premalignant lesions (OPLs) and of 357 healthy controls that were frequency-matched to patients according to age, sex and race. OPL patients had a significantly higher mtDNA copy number than the controls (1.36 ± 0.74 versus 1.11 ± 0.32; P < 0.001). In analyses stratified by sex, race, alcohol consumption and smoking status, the mtDNA copy number was higher in the OPL patients than in the controls in all the strata. Using the median mtDNA copy number in the control group as a cutoff, we found that individuals with a high mtDNA copy number had significantly higher risk of having OPLs than individuals with a low mtDNA copy number (adjusted odds ratio, 1.93; 95% confidence interval, 1.23-3.05, P = 0.004). Analysis of the joint effect of alcohol consumption and smoking revealed even greater risk for OPLs. Our results suggest that high mtDNA copy number in PBLs is significantly associated with having OPLs. To our knowledge, this is the first epidemiologic study to show that the mtDNA copy number may indicate the risk of cancer precursors.
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Affiliation(s)
- Yonggang He
- Department of Epidemiology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA, Department of Surgery, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Yilei Gong
- Department of Epidemiology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Jian Gu
- Department of Epidemiology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - J Jack Lee
- Department of Biostatistics, The University of Texas MD Anderson Center, Houston, TX 77030, USA and
| | - Scott M Lippman
- Moores Cancer Center, University of California San Diego, San Diego, CA 92093, USA
| | - Xifeng Wu
- Department of Epidemiology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA,
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311
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Shokolenko IN, Wilson GL, Alexeyev MF. The "fast" and the "slow" modes of mitochondrial DNA degradation. Mitochondrial DNA A DNA Mapp Seq Anal 2014; 27:490-8. [PMID: 24724936 DOI: 10.3109/19401736.2014.905829] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
In a living cell, oxidative stress resulting from an external or internal insult can result in mitochondrial DNA (mtDNA) damage and degradation. Here, we show that in HeLa cells, mtDNA can withstand relatively high levels of extracellular oxidant H2O2 before it is damaged to a point of degradation, and that mtDNA levels in these cells quickly recover after removal of the stressor. In contrast, mtDNA degradation in mouse fibroblast cells is induced at eight-fold lower concentrations of H2O2, and restoration of the lost mtDNA proceeds much slower. Importantly, mtDNA levels in HeLa cells continue to decline even after withdrawal of the stressor thus marking the "slow" mode of mtDNA degradation. Conversely, in mouse fibroblasts maximal loss of mtDNA is achieved during treatment, and is already detectable at 5 min after exposure, indicating the "fast" mode. These differences may modulate susceptibility to oxidative stress of those organs, which consist of multiple cell types.
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Affiliation(s)
- Inna N Shokolenko
- a Department of Cell Biology and Neuroscience , University of South Alabama , Mobile , AL , USA
| | - Glenn L Wilson
- a Department of Cell Biology and Neuroscience , University of South Alabama , Mobile , AL , USA
| | - Mikhail F Alexeyev
- a Department of Cell Biology and Neuroscience , University of South Alabama , Mobile , AL , USA
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312
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Da-Rè C, Franzolin E, Biscontin A, Piazzesi A, Pacchioni B, Gagliani MC, Mazzotta G, Tacchetti C, Zordan MA, Zeviani M, Bernardi P, Bianchi V, De Pittà C, Costa R. Functional characterization of drim2, the Drosophila melanogaster homolog of the yeast mitochondrial deoxynucleotide transporter. J Biol Chem 2014; 289:7448-59. [PMID: 24469456 PMCID: PMC3953259 DOI: 10.1074/jbc.m113.543926] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Revised: 01/22/2014] [Indexed: 12/03/2022] Open
Abstract
The CG18317 gene (drim2) is the Drosophila melanogaster homolog of the Saccharomyces cerevisiae Rim2 gene, which encodes a pyrimidine (deoxy)nucleotide carrier. Here, we tested if the drim2 gene also encodes for a deoxynucleotide transporter in the fruit fly. The protein was localized to mitochondria. Drosophila S2R(+) cells, silenced for drim2 expression, contained markedly reduced pools of both purine and pyrimidine dNTPs in mitochondria, whereas cytosolic pools were unaffected. In vivo drim2 homozygous knock-out was lethal at the larval stage, preceded by the following: (i) impaired locomotor behavior; (ii) decreased rates of oxygen consumption, and (iii) depletion of mtDNA. We conclude that the Drosophila mitochondrial carrier dRIM2 transports all DNA precursors and is essential to maintain mitochondrial function.
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Affiliation(s)
| | | | | | | | | | - Maria Cristina Gagliani
- the MicroScoBio Research Center, Department of Experimental Medicine, University of Genova, 16132 Genova, Italy
| | | | - Carlo Tacchetti
- the MicroScoBio Research Center, Department of Experimental Medicine, University of Genova, 16132 Genova, Italy
- the Experimental Imaging Center, San Raffaele Scientific Institute, 20132 Milano, Italy
| | | | - Massimo Zeviani
- the MRC Mitocondrial Biology Unit, University of Cambridge, Cambridge CB2 0XY, United Kingdom
| | - Paolo Bernardi
- the Department of Biomedical Sciences, University of Padova, 35131 Padova, Italy, and
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313
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Dang S, Qu Y, Wei J, Shao Y, Yang Q, Ji M, Shi B, Hou P. Low copy number of mitochondrial DNA (mtDNA) predicts worse prognosis in early-stage laryngeal cancer patients. Diagn Pathol 2014; 9:28. [PMID: 24499477 PMCID: PMC3916805 DOI: 10.1186/1746-1596-9-28] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2013] [Accepted: 12/31/2013] [Indexed: 12/29/2022] Open
Abstract
Objectives Alterations in mitochondrial DNA (mtDNA) copy number have been widely reported in various human cancers, and been considered to be an important hallmark of cancers. However, little is known about the value of copy number variations of mtDNA in the prognostic evaluation of laryngeal cancer. Design and methods Using real-time quantitative PCR method, we investigated mtDNA copy number in a cohort of laryngeal cancers (n =204) and normal laryngeal tissues (n =40), and explored the association of variable mtDNA copy number with clinical outcomes of laryngeal cancer patients. Results Our data showed that the relative mean mtDNA content was higher in the laryngeal cancer patients (11.91 ± 4.35 copies) than the control subjects (4.72 ± 0.70 copies). Moreover, we found that mtDNA content was negatively associated with cigarette smoking (pack-years), tumor invasion, and TNM stage. Notably, variable mtDNA content did not affect overall survival of laryngeal cancer patients. However, when the patients were categorized into early-stage and late-stage tumor groups according to TNM stage, we found that low mtDNA content was strongly associated with poor survival in the former, but not in the latter. Conclusions The present study demonstrated that low mtDNA content was strongly correlated with some of clinicopathological characteristics, such as cigarette smoking, tumor invasion and TNM stage. In addition, we found a strong link between low mtDNA content and worse survival of the patients with early-stage tumors. Taken together, low copy number of mtDNA may be a useful poor prognostic factor for early-stage laryngeal cancer patients. Virtual slides The virtual slides for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1841771572115955
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Affiliation(s)
| | | | | | | | | | | | | | - Peng Hou
- Department of Endocrinology, The First Affiliated Hospital of Xi'an Jiaotong University School of Medicine, 710061 Xi'an, the People's Republic of China.
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314
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Phillips NR, Sprouse ML, Roby RK. Simultaneous quantification of mitochondrial DNA copy number and deletion ratio: a multiplex real-time PCR assay. Sci Rep 2014; 4:3887. [PMID: 24463429 PMCID: PMC4894387 DOI: 10.1038/srep03887] [Citation(s) in RCA: 108] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2013] [Accepted: 12/24/2013] [Indexed: 12/25/2022] Open
Abstract
Mitochondrial dysfunction is implicated in a vast array of diseases and conditions, such as Alzheimer's disease, cancer, and aging. Alterations in mitochondrial DNA (mtDNA) may provide insight into the processes that either initiate or propagate this dysfunction. Here, we describe a unique multiplex assay which simultaneously provides assessments of mtDNA copy number and the proportion of genomes with common large deletions by targeting two mitochondrial sites and one nuclear locus. This probe-based, single-tube multiplex provides high specificity while eliminating well-to-well variability that results from assaying nuclear and mitochondrial targets individually.
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Affiliation(s)
- Nicole R. Phillips
- University of North Texas Health Science Center, Department of Molecular and Medical Genetics 3500 Camp Bowie Blvd, Fort Worth, TX 76107
| | - Marc L. Sprouse
- University of North Texas Health Science Center, Department of Molecular and Medical Genetics 3500 Camp Bowie Blvd, Fort Worth, TX 76107
| | - Rhonda K. Roby
- University of North Texas Health Science Center, Department of Molecular and Medical Genetics 3500 Camp Bowie Blvd, Fort Worth, TX 76107
- University of North Texas Health Science Center, Institute of Applied Genetics 3500 Camp Bowie Blvd, Fort Worth, TX 76107
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315
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Marine A, Krager KJ, Aykin-Burns N, Macmillan-Crow LA. Peroxynitrite induced mitochondrial biogenesis following MnSOD knockdown in normal rat kidney (NRK) cells. Redox Biol 2014; 2:348-57. [PMID: 24563852 PMCID: PMC3926114 DOI: 10.1016/j.redox.2014.01.014] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2013] [Revised: 01/15/2014] [Accepted: 01/16/2014] [Indexed: 12/02/2022] Open
Abstract
Superoxide is widely regarded as the primary reactive oxygen species (ROS) which initiates downstream oxidative stress. Increased oxidative stress contributes, in part, to many disease conditions such as cancer, atherosclerosis, ischemia/reperfusion, diabetes, aging, and neurodegeneration. Manganese superoxide dismutase (MnSOD) catalyzes the dismutation of superoxide into hydrogen peroxide which can then be further detoxified by other antioxidant enzymes. MnSOD is critical in maintaining the normal function of mitochondria, thus its inactivation is thought to lead to compromised mitochondria. Previously, our laboratory observed increased mitochondrial biogenesis in a novel kidney-specific MnSOD knockout mouse. The current study used transient siRNA mediated MnSOD knockdown of normal rat kidney (NRK) cells as the in vitro model, and confirmed functional mitochondrial biogenesis evidenced by increased PGC1α expression, mitochondrial DNA copy numbers and integrity, electron transport chain protein CORE II, mitochondrial mass, oxygen consumption rate, and overall ATP production. Further mechanistic studies using mitoquinone (MitoQ), a mitochondria-targeted antioxidant and L-NAME, a nitric oxide synthase (NOS) inhibitor demonstrated that peroxynitrite (at low micromolar levels) induced mitochondrial biogenesis. These findings provide the first evidence that low levels of peroxynitrite can initiate a protective signaling cascade involving mitochondrial biogenesis which may help to restore mitochondrial function following transient MnSOD inactivation. MnSOD knockdown in NRK cells results in a transient loss of MnSOD activity, increased nitrotyrosine and mitochondrial superoxide. MnSOD knockdown in NRK cells results in a transient induction of mitochondrial biogenesis. Nitric oxide synthase inhibition and Mitoquinone blocks mitochondrial biogenesis after MnSOD knockdown. Low doses of peroxynitrite induce biogenesis in NRK cells.
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Affiliation(s)
- Akira Marine
- Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Kimberly J Krager
- Division of Radiation Health, Department of Pharmaceutical Sciences, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Nukhet Aykin-Burns
- Division of Radiation Health, Department of Pharmaceutical Sciences, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Lee Ann Macmillan-Crow
- Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock, AR, USA
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316
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Lee JY, Lee DC, Im JA, Lee JW. Mitochondrial DNA copy number in peripheral blood is independently associated with visceral fat accumulation in healthy young adults. Int J Endocrinol 2014; 2014:586017. [PMID: 24707289 PMCID: PMC3953665 DOI: 10.1155/2014/586017] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/11/2013] [Revised: 12/22/2013] [Accepted: 01/01/2014] [Indexed: 11/17/2022] Open
Abstract
Aims. Visceral obesity is associated with an increased risk of cardiometabolic diseases and it is important to identify the underlying mechanisms. There is growing evidence that mitochondrial dysfunction is associated with metabolic disturbances related to visceral obesity. In addition, maintaining mitochondrial DNA (mtDNA) copy number is important for preserving mitochondrial function. Therefore, we investigated the relationship between mtDNA copy number and visceral fat in healthy young adults. Methods. A total of 94 healthy young subjects were studied. Biomarkers of metabolic risk factors were assessed along with body composition by computed tomography. mtDNA copy number was measured in peripheral leukocytes using real-time polymerase chain reaction (PCR) methods. Results. The mtDNA copy number correlated with BMI (r = -0.22, P = 0.04), waist circumference (r = -0.23, P = 0.03), visceral fat area (r = -0.28, P = -0.01), HDL-cholesterol levels (r = 0.25, P = 0.02), and hs-CRP (r = 0.32, P = 0.02) after adjusting for age and sex. Both stepwise and nonstepwise multiple regression analyses confirmed that visceral fat area was independently associated with mtDNA copy number (β = -0.33, P < 0.01, β = 0.32, and P = 0.03, resp.). Conclusions. An independent association between mtDNA content and visceral adiposity was identified. These data suggest that mtDNA copy number is a potential predictive marker for metabolic disturbances. Further studies are required to understand the causality and clinical significance of our findings.
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Affiliation(s)
- Jee-Yon Lee
- Department of Family Medicine, Severance Hospital, Yonsei University, College of Medicine, 250 Seongsanno, Seodaemun-gu 120-752, Republic of Korea
| | - Duk-Chul Lee
- Department of Family Medicine, Severance Hospital, Yonsei University, College of Medicine, 250 Seongsanno, Seodaemun-gu 120-752, Republic of Korea
| | - Jee-Aee Im
- Sport and Medicine Research Center, INTOTO Inc., 401 Dawoo BD, 90-6 Daeshin-Dong, Seodaemun-gu, Seoul 120-160, Republic of Korea
| | - Ji-Won Lee
- Department of Family Medicine, Severance Hospital, Yonsei University, College of Medicine, 250 Seongsanno, Seodaemun-gu 120-752, Republic of Korea
- *Ji-Won Lee:
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317
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Schroeder EA, Shadel GS. Crosstalk between mitochondrial stress signals regulates yeast chronological lifespan. Mech Ageing Dev 2013; 135:41-9. [PMID: 24373996 DOI: 10.1016/j.mad.2013.12.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2013] [Revised: 12/04/2013] [Accepted: 12/16/2013] [Indexed: 01/09/2023]
Abstract
Mitochondrial DNA (mtDNA) exists in multiple copies per cell and is essential for oxidative phosphorylation. Depleted or mutated mtDNA promotes numerous human diseases and may contribute to aging. Reduced TORC1 signaling in the budding yeast, Saccharomyces cerevisiae, extends chronological lifespan (CLS) in part by generating a mitochondrial ROS (mtROS) signal that epigenetically alters nuclear gene expression. To address the potential requirement for mtDNA maintenance in this response, we analyzed strains lacking the mitochondrial base-excision repair enzyme Ntg1p. Extension of CLS by mtROS signaling and reduced TORC1 activity, but not caloric restriction, was abrogated in ntg1Δ strains that exhibited mtDNA depletion without defects in respiration. The DNA damage response (DDR) kinase Rad53p, which transduces pro-longevity mtROS signals, is also activated in ntg1Δ strains. Restoring mtDNA copy number alleviated Rad53p activation and re-established CLS extension following mtROS signaling, indicating that Rad53p senses mtDNA depletion directly. Finally, DDR kinases regulate nucleus-mitochondria localization dynamics of Ntg1p. From these results, we conclude that the DDR pathway senses and may regulate Ntg1p-dependent mtDNA stability. Furthermore, Rad53p senses multiple mitochondrial stresses in a hierarchical manner to elicit specific physiological outcomes, exemplified by mtDNA depletion overriding the ability of Rad53p to transduce an adaptive mtROS longevity signal.
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Affiliation(s)
- Elizabeth A Schroeder
- Department of Pathology, Yale University School of Medicine, New Haven, CT 06520, United States; Department of Genetics, Yale University School of Medicine, New Haven, CT 06520, United States
| | - Gerald S Shadel
- Department of Pathology, Yale University School of Medicine, New Haven, CT 06520, United States; Department of Genetics, Yale University School of Medicine, New Haven, CT 06520, United States.
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318
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Horan MP, Cooper DN. The emergence of the mitochondrial genome as a partial regulator of nuclear function is providing new insights into the genetic mechanisms underlying age-related complex disease. Hum Genet 2013; 133:435-58. [DOI: 10.1007/s00439-013-1402-4] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2013] [Accepted: 11/23/2013] [Indexed: 12/17/2022]
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319
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Kam WWY, Banati RB. Effects of ionizing radiation on mitochondria. Free Radic Biol Med 2013; 65:607-619. [PMID: 23892359 DOI: 10.1016/j.freeradbiomed.2013.07.024] [Citation(s) in RCA: 238] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2013] [Revised: 07/16/2013] [Accepted: 07/16/2013] [Indexed: 01/08/2023]
Abstract
The current concept of radiobiology posits that damage to the DNA in the cell nucleus is the primary cause for the detrimental effects of radiation. However, emerging experimental evidence suggests that this theoretical framework is insufficient for describing extranuclear radiation effects, particularly the response of the mitochondria, an important site of extranuclear, coding DNA. Here, we discuss experimental observations of the effects of ionizing radiation on the mitochondria at (1) the DNA and (2) functional levels. The roles of mitochondria in (3) oxidative stress and (4) late radiation effects are discussed. In this review, we summarize the current understanding of targets for ionizing radiation outside the cell nucleus. Available experimental data suggest that an increase in the tumoricidal efficacy of radiation therapy might be achievable by targeting mitochondria. Likewise, more specific protection of mitochondria and its coding DNA should reduce damage to healthy cells exposed to ionizing radiation.
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Affiliation(s)
- Winnie Wai-Ying Kam
- Australian Nuclear Science and Technology Organisation, Lucas Heights, Sydney, New South Wales 2234, Australia; Medical Radiation Sciences, Faculty of Health Sciences, University of Sydney, Cumberland, Sydney, New South Wales 2141, Australia.
| | - Richard B Banati
- Australian Nuclear Science and Technology Organisation, Lucas Heights, Sydney, New South Wales 2234, Australia; Medical Radiation Sciences, Faculty of Health Sciences, University of Sydney, Cumberland, Sydney, New South Wales 2141, Australia; National Imaging Facility at Brain and Mind Research Institute (BMRI), University of Sydney, Camperdown, Sydney, New South Wales 2050, Australia
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320
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Pinto M, Moraes CT. Mitochondrial genome changes and neurodegenerative diseases. Biochim Biophys Acta Mol Basis Dis 2013; 1842:1198-207. [PMID: 24252612 DOI: 10.1016/j.bbadis.2013.11.012] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Revised: 11/06/2013] [Accepted: 11/08/2013] [Indexed: 12/12/2022]
Abstract
Mitochondria are essential organelles within the cell where most of the energy production occurs by the oxidative phosphorylation system (OXPHOS). Critical components of the OXPHOS are encoded by the mitochondrial DNA (mtDNA) and therefore, mutations involving this genome can be deleterious to the cell. Post-mitotic tissues, such as muscle and brain, are most sensitive to mtDNA changes, due to their high energy requirements and non-proliferative status. It has been proposed that mtDNA biological features and location make it vulnerable to mutations, which accumulate over time. However, although the role of mtDNA damage has been conclusively connected to neuronal impairment in mitochondrial diseases, its role in age-related neurodegenerative diseases remains speculative. Here we review the pathophysiology of mtDNA mutations leading to neurodegeneration and discuss the insights obtained by studying mouse models of mtDNA dysfunction.
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Affiliation(s)
- Milena Pinto
- Department of Neurology, University of Miami Miller School of Medicine, Miami, FL 33136, USA; Department of Cell Biology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Carlos T Moraes
- Department of Neurology, University of Miami Miller School of Medicine, Miami, FL 33136, USA; Neuroscience Graduate Program, University of Miami Miller School of Medicine, Miami, FL 33136, USA; Department of Cell Biology, University of Miami Miller School of Medicine, Miami, FL 33136, USA.
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321
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Dai JG, Zhang ZY, Liu QX, Min JX. Mitochondrial genome microsatellite instability and copy number alteration in lung carcinomas. Asian Pac J Cancer Prev 2013; 14:2393-9. [PMID: 23725147 DOI: 10.7314/apjcp.2013.14.4.2393] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
OBJECTIVE Mitochondrial DNA (mtDNA) is considered a hotspot of mutations in various tumors. However, the relationship between microsatellite instability (MSI) and mtDNA copy number alterations in lung cancer has yet to be fully clarifieds. In the current study, we investigated the copy number and MSI of mitochondrial genome in lung carcinomas, as well as their significance for cancer development. METHODS The copy number and MSI of mtDNA in 37 matched lung carcinoma/adjacent histological normal lung tissue samples were examined by polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) assays for sequence variation, followed by sequence analysis and fluorogenic 5'-nuclease real-time PCR. Student's t test and linear regression analyses were employed to analyze the association between mtDNA copy number alterations and mitochondrial MSI (mtMSI). RESULTS The mean copy number of mtDNA in lung carcinoma tissue samples was significantly lower than that of the adjacent histologically normal lung tissue samples (p < 0.001). mtMSI was detected in 32.4% (12/37) of lung carcinoma samples. The average copy number of mtDNA in lung carcinoma samples containing mtMSI was significantly lower than that in the other lung carcinoma samples (P < 0.05). CONCLUSIONS Results suggest that mtMSI may be an early and important event in the progression of lung carcinogenesis, particularly in association with variation in mtDNA copy number.
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Affiliation(s)
- Ji-Gang Dai
- Department of Thoracic Cardiovascular Surgery of Xinqiao Hospital, the Third Military Medical University, Chongqing, China
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322
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Zhang G, Qu Y, Dang S, Yang Q, Shi B, Hou P. Variable copy number of mitochondrial DNA (mtDNA) predicts worse prognosis in advanced gastric cancer patients. Diagn Pathol 2013; 8:173. [PMID: 24144008 PMCID: PMC4015835 DOI: 10.1186/1746-1596-8-173] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Accepted: 10/11/2013] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Change of mitochondrial DNA (mtDNA) copy number is widely reported in various human cancers, including gastric cancer, and is considered to be an important hallmark of cancers. However, there is remarkably little consensus on the value of variable mtDNA content in the prognostic evaluation of this cancer. METHODS Using real-time quantitative PCR approach, we examined mtDNA copy number in a cohort of gastric cancers and normal gastric tissues, and explored the association of variable mtDNA content with clinical outcomes of gastric cancer patients. RESULTS Our data showed that the majority of gastric cancer patients had low mtDNA content as compared to control subjects although the relative mean mtDNA content was higher in the former than the latter. Moreover, we found that variable mtDNA content was strongly associated with lymph node metastasis and cancer-related death of the patients with late-stage tumors. Notably, variable mtDNA content did not affect overall survival of gastric cancer patients, however, we found that increased mtDNA content was associated with poor survival in the patients with late-stage tumors. CONCLUSION In this study, we demonstrated that variable mtDNA content markedly increased the risk of lymph node metastasis and high mortality of the patients with late-stage tumors. Additionally, we found a strong link between increased mtDNA content and worse survival of the patients with late-stage tumors. Taken together, variable mtDNA content may be a valuable poor prognostic factor for advanced gastric cancer patients. VIRTUAL SLIDES The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1344721463103353.
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Affiliation(s)
| | | | | | | | | | - Peng Hou
- Department of Endocrinology, The First Affiliated Hospital of Xi'an Jiaotong University School of Medicine, Xi'an 710061, the People's Republic of China.
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323
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Mitochondrial DNA mutations and breast tumorigenesis. Biochim Biophys Acta Rev Cancer 2013; 1836:336-44. [PMID: 24140413 DOI: 10.1016/j.bbcan.2013.10.002] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Revised: 10/02/2013] [Accepted: 10/05/2013] [Indexed: 12/15/2022]
Abstract
Breast cancer is a heterogeneous disease and genetic factors play an important role in its genesis. Although mutations in tumor suppressors and oncogenes encoded by the nuclear genome are known to play a critical role in breast tumorigenesis, the contribution of the mitochondrial genome to this process is unclear. Like the nuclear genome, the mitochondrial genome also encodes proteins critical for mitochondrion functions such as oxidative phosphorylation (OXPHOS), which is known to be defective in cancer including breast cancer. Mitochondrial DNA (mtDNA) is more susceptible to mutations due to limited repair mechanisms compared to nuclear DNA (nDNA). Thus changes in mitochondrial genes could also contribute to the development of breast cancer. In this review we discuss mtDNA mutations that affect OXPHOS. Continuous acquisition of mtDNA mutations and selection of advantageous mutations ultimately leads to generation of cells that propagate uncontrollably to form tumors. Since irreversible damage to OXPHOS leads to a shift in energy metabolism towards enhanced aerobic glycolysis in most cancers, mutations in mtDNA represent an early event during breast tumorigenesis, and thus may serve as potential biomarkers for early detection and prognosis of breast cancer. Because mtDNA mutations lead to defective OXPHOS, development of agents that target OXPHOS will provide specificity for preventative and therapeutic agents against breast cancer with minimal toxicity.
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324
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Wang J, Shi X, Johnson RH, Kelbauskas L, Zhang W, Meldrum DR. Single-cell analysis reveals early manifestation of cancerous phenotype in pre-malignant esophageal cells. PLoS One 2013; 8:e75365. [PMID: 24116039 PMCID: PMC3792915 DOI: 10.1371/journal.pone.0075365] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2013] [Accepted: 08/12/2013] [Indexed: 01/03/2023] Open
Abstract
Cellular heterogeneity plays a pivotal role in a variety of functional processes in vivo including carcinogenesis. However, our knowledge about cell-to-cell diversity and how differences in individual cells manifest in alterations at the population level remains very limited mainly due to the lack of appropriate tools enabling studies at the single-cell level. We present a study on changes in cellular heterogeneity in the context of pre-malignant progression in response to hypoxic stress. Utilizing pre-malignant progression of Barrett's esophagus (BE) as a disease model system we studied molecular mechanisms underlying the progression from metaplastic to dysplastic (pre-cancerous) stage. We used newly developed methods enabling measurements of cell-to-cell differences in copy numbers of mitochondrial DNA, expression levels of a set of mitochondrial and nuclear genes involved in hypoxia response pathways, and mitochondrial membrane potential. In contrast to bulk cell studies reported earlier, our study shows significant differences between metaplastic and dysplastic BE cells in both average values and single-cell parameter distributions of mtDNA copy numbers, mitochondrial function, and mRNA expression levels of studied genes. Based on single-cell data analysis, we propose that mitochondria may be one of the key factors in pre-malignant progression in BE.
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Affiliation(s)
- Jiangxin Wang
- Center for Biosignatures Discovery Automation, The Biodesign Institute, Arizona State University, Tempe, Arizona, United States of America
| | - Xu Shi
- Center for Biosignatures Discovery Automation, The Biodesign Institute, Arizona State University, Tempe, Arizona, United States of America
| | - Roger H. Johnson
- Center for Biosignatures Discovery Automation, The Biodesign Institute, Arizona State University, Tempe, Arizona, United States of America
| | - Laimonas Kelbauskas
- Center for Biosignatures Discovery Automation, The Biodesign Institute, Arizona State University, Tempe, Arizona, United States of America
| | - Weiwen Zhang
- Center for Biosignatures Discovery Automation, The Biodesign Institute, Arizona State University, Tempe, Arizona, United States of America
| | - Deirdre R. Meldrum
- Center for Biosignatures Discovery Automation, The Biodesign Institute, Arizona State University, Tempe, Arizona, United States of America
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325
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Aluminium induced oxidative stress results in decreased mitochondrial biogenesis via modulation of PGC-1α expression. Toxicol Appl Pharmacol 2013; 273:365-80. [PMID: 24084166 DOI: 10.1016/j.taap.2013.09.012] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2013] [Revised: 09/02/2013] [Accepted: 09/19/2013] [Indexed: 12/31/2022]
Abstract
The present investigation was carried out to elucidate a possible molecular mechanism related to the effects of aluminium-induced oxidative stress on various mitochondrial respiratory complex subunits with special emphasis on the role of Peroxisome proliferator activated receptor gamma co-activator 1α (PGC-1α) and its downstream targets i.e. Nuclear respiratory factor-1(NRF-1), Nuclear respiratory factor-2(NRF-2) and Mitochondrial transcription factor A (Tfam) in mitochondrial biogenesis. Aluminium lactate (10mg/kgb.wt./day) was administered intragastrically to rats for 12 weeks. After 12 weeks of exposure, we found an increase in ROS levels, mitochondrial DNA oxidation and decrease in citrate synthase activity in the Hippocampus (HC) and Corpus striatum (CS) regions of rat brain. On the other hand, there was a decrease in the mRNA levels of the mitochondrial encoded subunits-NADH dehydrogenase (ND) subunits i.e. ND1, ND2, ND3, Cytochrome b (Cytb), Cytochrome oxidase (COX) subunits i.e. COX1, COX3, ATP synthase (ATPase) subunit 6 along with reduced expression of nuclear encoded subunits COX4, COX5A, COX5B of Electron transport chain (ETC). Besides, a decrease in mitochondrial DNA copy number and mitochondrial content in both regions of rat brain was observed. The PGC-1α was down-regulated in aluminium treated rats along with NRF-1, NRF-2 and Tfam, which act downstream from PGC-1α in aluminium treated rats. Electron microscopy results revealed a significant increase in the mitochondrial swelling, loss of cristae, chromatin condensation and decreases in mitochondrial number in case of aluminium treated rats as compared to control. So, PGC-1α seems to be a potent target for aluminium neurotoxicity, which makes it an almost ideal target to control or limit the damage that has been associated with the defective mitochondrial function seen in neurodegenerative diseases.
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326
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Marucci G, Maresca A, Caporali L, Farnedi A, Betts CM, Morandi L, de Biase D, Cerasoli S, Foschini MP, Bonora E, Vidone M, Romeo G, Perli E, Giordano C, d'Amati G, Gasparre G, Baruzzi A, Carelli V, Eusebi V. Oncocytic glioblastoma: a glioblastoma showing oncocytic changes and increased mitochondrial DNA copy number. Hum Pathol 2013; 44:1867-76. [PMID: 23664543 DOI: 10.1016/j.humpath.2013.02.014] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Revised: 02/23/2013] [Accepted: 02/28/2013] [Indexed: 02/05/2023]
Abstract
Ten cases of glioblastomas showing oncocytic changes are described. The tumors showed mononuclear to multinuclear cells and abundant, granular, eosinophilic cytoplasm. The cytoplasm of these same cells was filled by strongly immunoreactive mitochondria. At ultrastructure, numerous mitochondria, some of which were large, were evidenced in the cytoplasm of neoplastic cells. Finally, 9 of 10 of these cases had a significantly high mitochondrial DNA content compared with control tissue (P < .01). It seems that, for these tumors, the designation of oncocytic glioblastoma is appropriate. To the best of our knowledge, oncocytic changes have not been previously reported in such neoplasms. Oncocytic glioblastomas have to be added to the long list of various tumors that can manifest "unexpected" oncocytic changes in different organs. Albeit failing to show statistical significance (log-rank test, P = .597; Wilcoxon test, P = .233), we observed a trend for longer median survival in oncocytic glioblastomas, when compared with "ordinary" glioblastomas (median survival of 16 versus 8.7 months). Thus, it seems that the definition of neoplasms showing oncocytic changes, currently based on classic morphological parameters (ie, histology, ultrastructure, and immunohistochemistry), can be expanded by including the quantitative assessment of mitochondrial DNA content.
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Affiliation(s)
- Gianluca Marucci
- Department of Biomedical and NeuroMotor Sciences, University of Bologna, Section of Pathology, M. Malpighi, Bellaria Hospital, via Altura 3, 40139 Bologna, Italy
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327
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High glucose-induced oxidative stress increases the copy number of mitochondrial DNA in human mesangial cells. BIOMED RESEARCH INTERNATIONAL 2013; 2013:754946. [PMID: 23984405 PMCID: PMC3745925 DOI: 10.1155/2013/754946] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/04/2013] [Accepted: 07/08/2013] [Indexed: 01/01/2023]
Abstract
Oxidative damage to mitochondrial DNA (mtDNA) has been linked to the pathogenicity of diabetic nephropathy. We tested the hypothesis that mtDNA copy number may be increased in human mesangial cells in response to high glucose-induced reactive oxygen species (ROS) to compensate for damaged mtDNA. The effect of manganese superoxide dismutase mimetic (MnTBAP) on glucose-induced mtDNA copy number was also examined. The copy number of mtDNA was determined by real-time PCR in human mesangial cells cultured in 5 mM glucose, 25 mM glucose, and mannitol (osmotic control), as well as in cells cultured in 25 mM glucose in the presence and absence of 200 μM MnTBAP. Intracellular ROS was assessed by confocal microscopy and flow cytometry in human mesangial cells.
The copy number of mtDNA was significantly increased when human mesangial cells were incubated with 25 mM glucose compared to 5 mM glucose and mannitol. In addition, 25 mM glucose rapidly generated ROS in the cells, which was not detected in 5 mM glucose. Furthermore, mtDNA copy number was significantly decreased and maintained to normal following treatment of cells with 25 mM glucose and MnTBAP compared to 25 mM glucose alone. Inclusion of MnTBAP during 25 mM glucose incubation inhibited mitochondrial superoxide in human mesangial cells. Increased mtDNA copy number in human mesangial cells by high glucose could contribute to increased mitochondrial superoxide, and prevention of mtDNA copy number could have potential in retarding the development of diabetic nephropathy.
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328
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Phillips NR, Simpkins JW, Roby RK. Mitochondrial DNA deletions in Alzheimer's brains: a review. Alzheimers Dement 2013; 10:393-400. [PMID: 23850329 DOI: 10.1016/j.jalz.2013.04.508] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2013] [Revised: 04/02/2013] [Accepted: 04/30/2013] [Indexed: 11/29/2022]
Abstract
Mitochondrial dysfunction and increased oxidative stress have been associated with normal aging and are possibly implicated in the etiology of late-onset Alzheimer's disease (AD). DNA deletions, as well as other alterations, can result from oxidative damage to nucleic acids. Many studies during the past two decades have investigated the incidence of mitochondrial DNA deletions in postmortem brain tissues of late-onset AD patients compared with age-matched normal control subjects. Published studies are not entirely concordant, but their differences might shed light on the heterogeneity of AD itself. Our understanding of the role that mitochondrial DNA deletions play in disease progression may provide valuable information that could someday lead to a treatment.
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Affiliation(s)
- Nicole R Phillips
- Department of Forensic & Investigative Genetics, University of North Texas Health Science Center, Fort Worth, TX, USA.
| | - James W Simpkins
- Department of Physiology & Pharmacology, West Virginia University, Morgantown, WV, USA; Center for Basic and Translational Stroke Research, West Virginia University, Morgantown, WV, USA
| | - Rhonda K Roby
- Department of Forensic & Investigative Genetics, University of North Texas Health Science Center, Fort Worth, TX, USA; Institute of Applied Genetics, University of North Texas Health Science Center, Fort Worth, TX, USA
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329
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Shokolenko IN, Wilson GL, Alexeyev MF. Persistent damage induces mitochondrial DNA degradation. DNA Repair (Amst) 2013; 12:488-99. [PMID: 23721969 PMCID: PMC3683391 DOI: 10.1016/j.dnarep.2013.04.023] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2013] [Revised: 03/20/2013] [Accepted: 04/22/2013] [Indexed: 01/12/2023]
Abstract
Considerable progress has been made recently toward understanding the processes of mitochondrial DNA (mtDNA) damage and repair. However, a paucity of information still exists regarding the physiological effects of persistent mtDNA damage. This is due, in part, to experimental difficulties associated with targeting mtDNA for damage, while sparing nuclear DNA. Here, we characterize two systems designed for targeted mtDNA damage based on the inducible (Tet-ON) mitochondrial expression of the bacterial enzyme, exonuclease III, and the human enzyme, uracil-N-glyosylase containing the Y147A mutation. In both systems, damage was accompanied by degradation of mtDNA, which was detectable by 6h after induction of mutant uracil-N-glycosylase and by 12h after induction of exoIII. Unexpectedly, increases in the steady-state levels of single-strand lesions, which led to degradation, were small in absolute terms indicating that both abasic sites and single-strand gaps may be poorly tolerated in mtDNA. mtDNA degradation was accompanied by the loss of expression of mtDNA-encoded COX2. After withdrawal of the inducer, recovery from mtDNA depletion occurred faster in the system expressing exonuclease III, but in both systems reduced mtDNA levels persisted longer than 144h after doxycycline withdrawal. mtDNA degradation was followed by reduction and loss of respiration, decreased membrane potential, reduced cell viability, reduced intrinsic reactive oxygen species production, slowed proliferation, and changes in mitochondrial morphology (fragmentation of the mitochondrial network, rounding and "foaming" of the mitochondria). The mutagenic effects of abasic sites in mtDNA were low, which indicates that damaged mtDNA molecules may be degraded if not rapidly repaired. This study establishes, for the first time, that mtDNA degradation can be a direct and immediate consequence of persistent mtDNA damage and that increased ROS production is not an invariant consequence of mtDNA damage.
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Affiliation(s)
- Inna N. Shokolenko
- Department of Cell Biology and Neuroscience, University of South Alabama, Mobile, AL (USA) 36688. Tel (251) 460-6772, Fax (251) 460-6771
| | - Glenn L. Wilson
- Department of Cell Biology and Neuroscience, University of South Alabama, Mobile, AL (USA) 36688. Tel (251) 460-6765, Fax (251) 460-6771
| | - Mikhail F. Alexeyev
- Department of Cell Biology and Neuroscience, University of South Alabama, Mobile, AL (USA) 36688
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330
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Feng YM, Jia YF, Su LY, Wang D, Lv L, Xu L, Yao YG. Decreased mitochondrial DNA copy number in the hippocampus and peripheral blood during opiate addiction is mediated by autophagy and can be salvaged by melatonin. Autophagy 2013; 9:1395-406. [PMID: 23800874 DOI: 10.4161/auto.25468] [Citation(s) in RCA: 90] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Drug addiction is a chronic brain disease that is a serious social problem and causes enormous financial burden. Because mitochondrial abnormalities have been associated with opiate addiction, we examined the effect of morphine on mtDNA levels in rat and mouse models of addiction and in cultured cells. We found that mtDNA copy number was significantly reduced in the hippocampus and peripheral blood of morphine-addicted rats and mice compared with control animals. Concordantly, decreased mtDNA copy number and elevated mtDNA damage were observed in the peripheral blood from opiate-addicted patients, indicating detrimental effects of drug abuse and stress. In cultured rat pheochromocytoma (PC12) cells and mouse neurons, morphine treatment caused many mitochondrial defects, including a reduction in mtDNA copy number that was mediated by autophagy. Knockdown of the Atg7 gene was able to counteract the loss of mtDNA copy number induced by morphine. The mitochondria-targeted antioxidant melatonin restored mtDNA content and neuronal outgrowth and prevented the increase in autophagy upon morphine treatment. In mice, coadministration of melatonin with morphine ameliorated morphine-induced behavioral sensitization, analgesic tolerance and mtDNA content reduction. During drug withdrawal in opiate-addicted patients and improvement of protracted abstinence syndrome, we observed an increase of serum melatonin level. Taken together, our study indicates that opioid addiction is associated with mtDNA copy number reduction and neurostructural remodeling. These effects appear to be mediated by autophagy and can be salvaged by melatonin.
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Affiliation(s)
- Yue-Mei Feng
- Key Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences & Yunnan Province; Kunming Institute of Zoology; Kunming, Yunnan China; University of Chinese Academy of Sciences; Beijing, China
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331
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Thyagarajan B, Wang R, Nelson H, Barcelo H, Koh WP, Yuan JM. Mitochondrial DNA copy number is associated with breast cancer risk. PLoS One 2013; 8:e65968. [PMID: 23776581 PMCID: PMC3680391 DOI: 10.1371/journal.pone.0065968] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2013] [Accepted: 05/03/2013] [Indexed: 12/26/2022] Open
Abstract
Mitochondrial DNA (mtDNA) copy number in peripheral blood is associated with increased risk of several cancers. However, data from prospective studies on mtDNA copy number and breast cancer risk are lacking. We evaluated the association between mtDNA copy number in peripheral blood and breast cancer risk in a nested case-control study of 183 breast cancer cases with pre-diagnostic blood samples and 529 individually matched controls among participants of the Singapore Chinese Health Study. The mtDNA copy number was measured using real time PCR. Conditional logistic regression analyses showed that there was an overall positive association between mtDNA copy number and breast cancer risk (Ptrend = 0.01). The elevated risk for higher mtDNA copy numbers was primarily seen for women with <3 years between blood draw and cancer diagnosis; ORs (95% CIs) for 2nd, 3rd, 4th, and 5th quintile of mtDNA copy number were 1.52 (0.61, 3.82), 2.52 (1.03, 6.12), 3.12 (1.31, 7.43), and 3.06 (1.25, 7.47), respectively, compared with the 1st quintile (Ptrend = 0.004). There was no association between mtDNA copy number and breast cancer risk among women who donated a blood sample ≥3 years before breast cancer diagnosis (Ptrend = 0.41). This study supports a prospective association between increased mtDNA copy number and breast cancer risk that is dependent on the time interval between blood collection and breast cancer diagnosis. Future studies are warranted to confirm these findings and to elucidate the biological role of mtDNA copy number in breast cancer risk.
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Affiliation(s)
- Bharat Thyagarajan
- Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, Minnesota, United States of America.
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332
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Fedorova LV, Sodhi K, Gatto-Weis C, Puri N, Hinds TD, Shapiro JI, Malhotra D. Peroxisome proliferator-activated receptor δ agonist, HPP593, prevents renal necrosis under chronic ischemia. PLoS One 2013; 8:e64436. [PMID: 23691217 PMCID: PMC3654981 DOI: 10.1371/journal.pone.0064436] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2012] [Accepted: 04/15/2013] [Indexed: 12/15/2022] Open
Abstract
The Goldblatt’s 2 kidney 1 clip (2K1C) rat animal model of renovascular hypertension is characterized by ischemic nephropathy of the clipped kidney. 2K1C rats were treated with a specific peroxisome proliferator-activated receptor δ (PPARδ) agonist, HPP593. Clipped kidneys from untreated rats developed tubular and glomerular necrosis and massive interstitial, periglomerular and perivascular fibrosis. HPP593 kidneys did not exhibit any histochemical features of necrosis; fibrotic lesions were present only in perivascular areas. Necrosis in the untreated clipped kidneys was associated with an increased oxidative stress, up regulation and mitochondrial translocation of the pro-death protein BNIP3 specifically in tubules. In the kidneys of HPP593-treated rats oxidative stress was attenuated and BNIP3 protein decreased notably in the mitochondrial fraction when compared to untreated animals. In untreated clipped kidneys, mitochondria were dysfunctional as revealed by perturbations in the levels of MCAD, COXIV, TFAM, and Parkin proteins and AMPK activation, while in HPP593-treated rats these proteins remained at the physiological levels. Nuclear amounts of oxidative stress-responsive proteins, NRF1 and NRF2 were below physiological levels in treated kidneys. Mitochondrial biogenesis and autophagy were inhibited similarly in both treated and untreated 2K1C kidneys as indicated by a decrease in PGC1-α and deficiency of the autophagy-essential proteins LC3-II and ATG5. However, HPP593 treatment resulted in increased accumulation of p62 protein, an autophagic substrate and an enhancer of NRF2 activity. Therefore, inhibition of BNIP3 activation by the preservation of mitochondrial function and control of oxidative stress by PPARδ is the most likely mechanism to account for the prevention of necrotic death in the kidney under conditions of persistent ischemia.
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Affiliation(s)
- Larisa V Fedorova
- Department of Medicine, The University of Toledo School of Medicine, Toledo, Ohio, United States of America.
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333
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Alexeyev M, Shokolenko I, Wilson G, LeDoux S. The maintenance of mitochondrial DNA integrity--critical analysis and update. Cold Spring Harb Perspect Biol 2013; 5:a012641. [PMID: 23637283 DOI: 10.1101/cshperspect.a012641] [Citation(s) in RCA: 286] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
DNA molecules in mitochondria, just like those in the nucleus of eukaryotic cells, are constantly damaged by noxious agents. Eukaryotic cells have developed efficient mechanisms to deal with this assault. The process of DNA repair in mitochondria, initially believed nonexistent, has now evolved into a mature area of research. In recent years, it has become increasingly appreciated that mitochondria possess many of the same DNA repair pathways that the nucleus does. Moreover, a unique pathway that is enabled by high redundancy of the mitochondrial DNA and allows for the disposal of damaged DNA molecules operates in this organelle. In this review, we attempt to present a unified view of our current understanding of the process of DNA repair in mitochondria with an emphasis on issues that appear controversial.
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Affiliation(s)
- Mikhail Alexeyev
- Department of Cell Biology and Neuroscience, University of South Alabama, Mobile, AL 36688, USA
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334
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Hou L, Zhang X, Dioni L, Barretta F, Dou C, Zheng Y, Hoxha M, Bertazzi PA, Schwartz J, Wu S, Wang S, Baccarelli AA. Inhalable particulate matter and mitochondrial DNA copy number in highly exposed individuals in Beijing, China: a repeated-measure study. Part Fibre Toxicol 2013; 10:17. [PMID: 23628000 PMCID: PMC3649952 DOI: 10.1186/1743-8977-10-17] [Citation(s) in RCA: 90] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2012] [Accepted: 04/12/2013] [Indexed: 12/30/2022] Open
Abstract
Background Mitochondria are both a sensitive target and a primary source of oxidative stress, a key pathway of air particulate matter (PM)-associated diseases. Mitochondrial DNA copy number (MtDNAcn) is a marker of mitochondrial damage and malfunctioning. We evaluated whether ambient PM exposure affects MtDNAcn in a highly-exposed population in Beijing, China. Methods The Beijing Truck Driver Air Pollution Study was conducted shortly before the 2008 Beijing Olympic Games (June 15-July 27, 2008) and included 60 truck drivers and 60 office workers. Personal PM2.5 and elemental carbon (EC, a tracer of traffic particles) were measured during work hours using portable monitors. Post-work blood samples were obtained on two different days. Ambient PM10 was averaged from 27 monitoring stations in Beijing. Blood MtDNAcn was determined by real-time PCR and examined in association with particle levels using mixed-effect models. Results In all participants combined, MtDNAcn was negatively associated with personal EC level measured during work hours (β=−0.059, 95% CI: -0.011; -0.0006, p=0.03); and 5-day (β=−0.017, 95% CI: -0.029;-0.005, p=0.01) and 8-day average ambient PM10 (β=−0.008, 95% CI: -0.043; -0.008, p=0.004) after adjusting for possible confounding factors, including study groups. MtDNAcn was also negatively associated among office workers with EC (β=−0.012, 95% CI: -0.022;-0.002, p=0.02) and 8-day average ambient PM10 (β=−0.030, 95% CI: -0.051;-0.008, p=0.007). Conclusions We observed decreased blood MtDNAcn in association with increased exposure to EC during work hours and recent ambient PM10 exposure. Our results suggest that MtDNAcn may be influenced by particle exposures. Further studies are required to determine the roles of MtDNAcn in the etiology of particle-related diseases.
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Affiliation(s)
- Lifang Hou
- Department of Preventive Medicine Feinberg, School of Medicine Northwestern University, Chicago, IL 60611, USA.
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335
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Abstract
A plethora of somatic mutations and germline variations in mitochondrial DNA (mtDNA) have been increasingly reported in numerous cancer entities including osteosarcoma. However, it remains largely unclear whether mtDNA copy number changes occur during the multistep process of osteosarcoma carcinogenesis. For this purpose, we determined quantitative mtDNA levels in 31 primary osteosarcoma specimens and 5 normal bone tissue samples using a real-time polymerase chain reaction assay. Our data showed that the average mtDNA amount was significantly reduced in osteosarcoma tissues compared with normal bone controls. The copy number of mtDNA was statistically associated with tumor metastasis. There was an approximately 2-fold decrease of mtDNA quantity in tumors with metastasis than that in low-grade tumors without metastasis. Furthermore, change in mtDNA content was linked with somatic mutations in the D-loop regulatory region. Tumors carrying somatic D-loop mutations, at the polycytidine stretch between nucleotide positions 303 and 309 or close to the replication origin sites of the heavy strand, had significantly lowered mtDNA levels in comparison with those without mutations. Taken together, these results provide evidence for the first time that reduced mtDNA content may be critically implicated in the development and/or progression of osteosarcoma. Somatic D-loop mutation is likely one key factor among others leading to altered mtDNA amount in osteosarcoma.
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Affiliation(s)
- Man Yu
- Ontario Cancer Institute/Princess Margaret Hospital, University Health Network, Toronto, ON, Canada M5G 2M9.
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336
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Abstract
Mitochondrial DNA (mtDNA) is essential for aerobic energy production in eukaryotic cells, and mutations in this genome can lead to mitochondrial dysfunction. Human mtDNA mutations are typically heteroplasmic, a mix of mutant and wild-type genomes, which can present as a heterogeneous group of disorders ranging in severity from mild to fatal, and commonly affecting highly aerobic tissues such as heart, skeletal muscle, and neurons. During the 1990s, many research groups started to notice that mtDNA mutations could segregate depending upon the mutation and tissue. This segregation pattern can have a direct effect on the onset and severity of these mutations. However, these segregation patterns could not be easily explained by respiratory chain function, implying that there is regulation of mtDNA independent of its bioenergetic role. A lot of research on this topic has been largely descriptive, but over the last several years advances in mitochondrial biology have provided some mechanistic insight into the regulation of the organelle and its genome. This review addresses these advances with respect to somatic segregation of mtDNA in mammals.
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Affiliation(s)
- Riikka Jokinen
- Research Programs Unit-Molecular Neurology, and Institute of Biomedicine, Biomedicum Helsinki, University of Helsinki, Helsinki, Finland
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337
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Xie H, Lev D, Gong Y, Wang S, Pollock RE, Wu X, Gu J. Reduced mitochondrial DNA copy number in peripheral blood leukocytes increases the risk of soft tissue sarcoma. Carcinogenesis 2013; 34:1039-43. [DOI: 10.1093/carcin/bgt023] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
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338
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Abstract
Since the early twentieth century, inheritance was seen as the inheritance of genes. Concurrent with the acceptance of the genetic theory of inheritance was the rejection of the idea that the cytoplasm of the oocyte could also play a role in inheritance and a corresponding devaluation of embryology as a discipline critical for understanding human development. Development, and variation in development, came to be viewed solely as matters of genetic inheritance and genetic variation. We now know that inheritance is a matter of both genetic and cytoplasmic inheritance. A growing awareness of the centrality of the cytoplasm in explaining both human development and phenotypic variation has been promoted by two contemporaneous developments: the continuing elaboration of the molecular mechanisms of epigenetics and the global rise of artificial reproductive technologies. I review recent developments in the ongoing elaboration of the role of the cytoplasm in human inheritance and development.
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Affiliation(s)
- Evan Charney
- Sanford School of Public Policy, Duke University, Durham, NC, USA.
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339
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Part II. Mitochondrial mutational status of high nitric oxide adapted cell line BT-20 (BT-20-HNO) as it relates to human primary breast tumors. Tumour Biol 2012; 34:337-47. [PMID: 23238816 DOI: 10.1007/s13277-012-0555-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2012] [Accepted: 10/04/2012] [Indexed: 12/20/2022] Open
Abstract
Mitochondria combine hydrogen and oxygen to produce heat and adenosine triphosphate (ATP). As a toxic by-product of oxidative phosphorylation (OXPHOS), mitochondria generate reactive oxygen species (ROS). These free radicals may cause damage to mitochondrial DNA (mtDNA) and other molecules in the cell. Nitric oxide (NO) plays an important role in the biology of human cancers, including breast cancer; however, it is still unclear how NO might affect the mitochondrial genome. The aim of the current study is to determine the role of mtDNA in the breast oncogenic process. Using DNA sequencing, we studied one breast cancer cell line as a model system to investigate the effects of oxidative stress. The BT-20 cell line was fully adapted to increasing concentrations of the NO donor DETA-NONOate and is referred to as BT-20-HNO, a high NO (HNO) cell line. The HNO cell line is biologically different from the "parent" cell line from which it originated. Moreover, we investigated 71 breast cancer biopsies and the corresponding noncancerous breast tissues. The free radical NO was able to generate somatic mtDNA mutations in the BT-20-HNO cell line that were missing in the BT-20 parent cell line. We identified two somatic mutations, A4767G and G13481A, which changed the amino acid residues. Another two point mutations were identified in the mtDNA initiation replication site at nucleotide 57 and at the 'hot spot' cytidine-rich D300-310 segment. Furthermore, the NO regulated the mtDNA copy number and selected different mtDNA populations by clonal expansion. Interestingly, we identified eight somatic mutations in the coding regions of mtDNAs of eight breast cancer patients (8/71, 11.2 %). All of these somatic mutations changed amino acid residues in the highly conserved regions of mtDNA which potentially leads to mitochondrial dysfunctions. The other two somatic mtDNA mutations in the displacement loop (D-loop) region [303:315 C(7-8)TC(6) and nucleotide 57] were distributed among 14 patients (14/71, 19.7 %). Importantly, of these 14 patients, six had mutations in the p53 gene. These results validate the BT-20 parent/HNO cell line model system as a means to study ROS damage in mtDNA, as it parallels the results found in a subset of the patient population.
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340
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Abstract
AbstractThe science of genetics is undergoing a paradigm shift. Recent discoveries, including the activity of retrotransposons, the extent of copy number variations, somatic and chromosomal mosaicism, and the nature of the epigenome as a regulator of DNA expressivity, are challenging a series of dogmas concerning the nature of the genome and the relationship between genotype and phenotype. According to three widely held dogmas, DNA is the unchanging template of heredity, is identical in all the cells and tissues of the body, and is the sole agent of inheritance. Rather than being an unchanging template, DNA appears subject to a good deal of environmentally induced change. Instead of identical DNA in all the cells of the body, somatic mosaicism appears to be the normal human condition. And DNA can no longer be considered the sole agent of inheritance. We now know that the epigenome, which regulates gene expressivity, can be inherited via the germline. These developments are particularly significant for behavior genetics for at least three reasons: First, epigenetic regulation, DNA variability, and somatic mosaicism appear to be particularly prevalent in the human brain and probably are involved in much of human behavior; second, they have important implications for the validity of heritability and gene association studies, the methodologies that largely define the discipline of behavior genetics; and third, they appear to play a critical role in development during the perinatal period and, in particular, in enabling phenotypic plasticity in offspring. I examine one of the central claims to emerge from the use of heritability studies in the behavioral sciences, the principle of minimal shared maternal effects, in light of the growing awareness that the maternal perinatal environment is a critical venue for the exercise of adaptive phenotypic plasticity. This consideration has important implications for both developmental and evolutionary biology.
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341
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Anglin RES, Mazurek MF, Tarnopolsky MA, Rosebush PI. The mitochondrial genome and psychiatric illness. Am J Med Genet B Neuropsychiatr Genet 2012; 159B:749-59. [PMID: 22887963 DOI: 10.1002/ajmg.b.32086] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2012] [Accepted: 07/09/2012] [Indexed: 02/01/2023]
Abstract
Psychiatric disorders are a leading cause of morbidity and mortality, yet their underlying pathophysiology remains unclear. Searches for a genetic cause of bipolar disorder, schizophrenia, and major depressive disorder have yielded inconclusive results. There is increasing interest in the possibility that defects in the mitochondrial genome may play an important role in psychiatric illness. We undertook a review of the literature investigating mitochondria and adult psychiatric disorders. MEDLINE, PsycINFO, and EMBASE were searched from their inception through September 2011, and the reference lists of identified articles were reviewed for additional studies. While multiple lines of evidence, including clinical, genetic, ultrastructural, and biochemical studies, support the involvement of mitochondria in the pathophysiology of psychiatric illness, many studies have methodological limitations and their findings have not been replicated. Clinical studies suggest that psychiatric features can be prominent, and the presenting features of mitochondrial disorders. There is limited but inconsistent evidence for the involvement of mitochondrial DNA haplogroups and mitochondria-related nuclear gene polymorphisms, and for mitochondrial ultrastructural and biochemical abnormalities in psychiatric illness. The current literature suggests that mitochondrial dysfunction and mitochondrial genetic variations may play an important role in psychiatric disorders, but additional methodologically rigorous and adequately powered studies are needed before definitive conclusions can be drawn.
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Affiliation(s)
- Rebecca E S Anglin
- Department of Psychiatry & Behavioural Neurosciences, McMaster University, Hamilton, Ontario, Canada.
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342
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Jeong SH, Song IS, Kim HK, Lee SR, Song S, Suh H, Yoon YG, Yoo YH, Kim N, Rhee BD, Ko KS, Han J. An analogue of resveratrol HS-1793 exhibits anticancer activity against MCF-7 cells via inhibition of mitochondrial biogenesis gene expression. Mol Cells 2012; 34:357-65. [PMID: 23104437 PMCID: PMC3887771 DOI: 10.1007/s10059-012-0081-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2012] [Revised: 07/24/2012] [Accepted: 09/07/2012] [Indexed: 12/20/2022] Open
Abstract
Resveratrol is a phytoalexin and polyphenol derived from grapes, berries, and peanuts. It has been shown to mediate death of a wide variety of cancer cells. Although resveratrol is considered an important potential chemotherapeutic agent, it is required at high doses to achieve a biologically or physiologically significant effect, which may be impractical for treating cancer. Thus, a more stable and potent derivative of resveratrol, with more effective tumoricidal activity, must be developed. A novel resveratrol analog, HS-1793, has recently been synthesized and was determined to exhibit a greater decrease in cancer cell viability than resveratrol. However, the underlying mechanism of HS-1793-induced cancer cell death remains unknown. We thus investigated the mechanism by which HS-1793 induces cell death and assessed whether this occurs through a mitochondrial-mediated mechanism. Using the MCF-7 breast cancer cell line, we determined that HS-1793 treatment significantly increased cell death at a relatively low dose compared with resveratrol. HS-1793 treatment more significantly decreased mitochondrial membrane potential, cellular ATP concentration, and cellular oxygen consumption rate than resveratrol treatment. At the molecular level, HS-1793 treatment down-regulated the expression of major mitochondrial biogenesis-regulating proteins, including mitochondrial transcriptional factor A (TFAM), Tu translation elongation factor (TUFM), and single-stranded DNA-binding protein. We conclude that HS- 1793 acts by regulating the expression of TFAM and TUFM, leading to a block in normal mitochondrial function, which sensitizes cancer cells to cell death. We therefore propose that HS-1793 can be a useful chemosensitization agent, which together with other such agents can efficiently target cancer cells.
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Affiliation(s)
- Seung Hun Jeong
- National Research Laboratory for Mitochondrial Signaling, Department of Physiology, College of Medicine, Cardiovascular and Metabolic Disease Center, Inje University, Busan 614-735, Korea
| | - In Sung Song
- National Research Laboratory for Mitochondrial Signaling, Department of Physiology, College of Medicine, Cardiovascular and Metabolic Disease Center, Inje University, Busan 614-735, Korea
| | - Hyoung Kyu Kim
- National Research Laboratory for Mitochondrial Signaling, Department of Physiology, College of Medicine, Cardiovascular and Metabolic Disease Center, Inje University, Busan 614-735, Korea
| | - Sung Ryul Lee
- National Research Laboratory for Mitochondrial Signaling, Department of Physiology, College of Medicine, Cardiovascular and Metabolic Disease Center, Inje University, Busan 614-735, Korea
| | | | | | | | | | - Nari Kim
- National Research Laboratory for Mitochondrial Signaling, Department of Physiology, College of Medicine, Cardiovascular and Metabolic Disease Center, Inje University, Busan 614-735, Korea
| | - Byoung Doo Rhee
- National Research Laboratory for Mitochondrial Signaling, Department of Physiology, College of Medicine, Cardiovascular and Metabolic Disease Center, Inje University, Busan 614-735, Korea
| | - Kyung Soo Ko
- National Research Laboratory for Mitochondrial Signaling, Department of Physiology, College of Medicine, Cardiovascular and Metabolic Disease Center, Inje University, Busan 614-735, Korea
| | - Jin Han
- National Research Laboratory for Mitochondrial Signaling, Department of Physiology, College of Medicine, Cardiovascular and Metabolic Disease Center, Inje University, Busan 614-735, Korea
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343
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Yen HH, Shih KL, Lin TT, Su WW, Soon MS, Liu CS. Decreased mitochondrial deoxyribonucleic acid and increased oxidative damage in chronic hepatitis C. World J Gastroenterol 2012; 18:5084-9. [PMID: 23049218 PMCID: PMC3460336 DOI: 10.3748/wjg.v18.i36.5084] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/10/2012] [Revised: 05/09/2012] [Accepted: 05/13/2012] [Indexed: 02/06/2023] Open
Abstract
AIM: To determine whether alteration of the mitochondria DNA (mtDNA) copy number and its oxidative damage index (mtDNA∆CT) can be detected by analysis of peripheral blood cells in hepatitis C virus (HCV)-infected patients.
METHODS: This study enrolled two groups of patients aged 40-60 years: a control group and an HCV-infected group in Department of Gastroenterology and Hepatology in Changhua Christian Hospital. Patients with co-infection with hepatitis B virus or human immunodeficiency virus, autoimmune disease, malignant neoplasia, pregnancy, thyroid disease, or alcohol consumption > 40 g/d were excluded. HCV-infected patients who met the following criteria were included: (1) positive HCV antibodies for > 6 mo; (2) alanine aminotransferase (ALT) levels more than twice the upper limit of normal on at least two occasions during the past 6 mo; and (3) histological fibrosis stage higher than F1. The mtDNA copy number and oxidative damage index of HCV mtDNA (mtDNA∆CT) were measured in peripheral blood leukocytes. The association between mtDNA copy number and mtDNA∆CT was further analyzed using clinical data.
RESULTS: Forty-seven normal controls (male/female: 26/21, mean age 50.51 ± 6.15 years) and 132 HCV-infected patients (male/female: 76/61, mean age 51.65 ± 5.50 years) were included in the study. The genotypes of HCV-infected patients include type 1a (n = 3), type 1b (n = 83), type 2a (n = 32), and type 2b (n = 14). Liver fibrosis stages were distributed as follows: F1/F2/F3/F4 = 1/61/45/25 and activity scores were A0/A1/A2/A3 = 7/45/55/25. There were no age or gender differences between the two groups. HCV-infected patients had higher hepatitis activity (aspartate transaminase levels 108.77 ± 60.73 vs 23.19 ± 5.47, P < 0.01; ALT levels 168.69 ± 93.12 vs 23.15 ± 9.45, P < 0.01) and lower platelet count (170.40 ± 58.00 vs 251.24 ± 63.42, P < 0.01) than controls. The mtDNA copy number was lower in HCV-infected patients than in controls (173.49 vs 247.93, P < 0.05). The mtDNA∆CT was higher in HCV-infected patients than in controls (2.92 vs 0.64, P < 0.05). To clarify the clinical significance of these results in HCV-infected patients, their association with different clinical parameters among HCV-infected patients was analyzed. A negative association was found between mtDNA copy number and elevated aspartate transaminase levels (r = -0.17, P < 0.05). Changes in mtDNA copy number were not associated with HCV RNA levels, HCV genotypes, liver fibrosis severity, or inflammatory activity in the liver biopsy specimen. However, a correlation was observed between mtDNA∆CT and platelet count (r = -0.22, P < 0.01), HCV RNA level (r = 0.36, P < 0.01), and hepatitis activity (r = 0.20, P = 0.02). However, no difference in the change in mtDNA∆CT was observed between different fibrosis stages or HCV genotypes.
CONCLUSION: Oxidative stress and mtDNA damage are detectable in patient’s peripheral leukocytes. Increased leukocyte mtDNA∆CT correlates with higher HCV viremia, increased hepatitis activity, and lower platelet count.
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344
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The relationship between leukocyte mitochondrial DNA contents and metabolic syndrome in postmenopausal women. Menopause 2012; 19:582-7. [PMID: 22354267 DOI: 10.1097/gme.0b013e31823a3e46] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE Menopause is associated with increased risk of metabolic syndrome. There is growing evidence that mitochondrial dysfunction may lead to obesity and insulin resistance, which are major components of metabolic syndrome. The purpose of this study was to illuminate the relationship between mitochondrial function using leukocyte mitochondrial DNA copy number and metabolic syndrome in postmenopausal women. METHODS The present study included 144 postmenopausal women. Women with cardiovascular disease were excluded from the study sample. Anthropometric evaluation and biochemical tests were performed. Leukocyte mitochondrial DNA copy numbers were then measured. RESULTS The levels of leukocyte mitochondrial DNA copy number were lower among participants with metabolic syndrome than among those without metabolic syndrome (P < 0.01). As the number of components of metabolic syndrome increased, the concentration of leukocyte mitochondrial DNA copy number decreased (P = 0.02). Leukocyte mitochondrial DNA copy number was negatively correlated with waist circumference (r = -0.19, P = 0.03), fasting insulin (r = -0.19, P = 0.03), total cholesterol (r = -0.22, P < 0.01), and triglyceride (r = -0.37, P < 0.01). Leukocyte mitochondrial DNA copy number was positively associated with serum 25-hydroxyvitamin D levels (r = 0.94, P = <0.01). Multiple logistic regression analysis showed that leukocyte mitochondrial DNA copy number (odds ratio, 0.030; 95% CI, 0.002-0.437, P = 0.01) was independently associated with metabolic syndrome after adjustment for potential confounding variables including age, body mass index, homeostasis model assessment of insulin resistance, 25-hydroxyvitamin D, adiponectin, and high-sensitivity C-reactive protein. CONCLUSIONS Leukocyte mitochondrial DNA copy number was independently associated with metabolic syndrome in postmenopausal women.
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345
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Janssen BG, Munters E, Pieters N, Smeets K, Cox B, Cuypers A, Fierens F, Penders J, Vangronsveld J, Gyselaers W, Nawrot TS. Placental mitochondrial DNA content and particulate air pollution during in utero life. ENVIRONMENTAL HEALTH PERSPECTIVES 2012; 120:1346-52. [PMID: 22626541 PMCID: PMC3440109 DOI: 10.1289/ehp.1104458] [Citation(s) in RCA: 174] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2011] [Accepted: 05/24/2012] [Indexed: 05/19/2023]
Abstract
BACKGROUND Studies emphasize the importance of particulate matter (PM) in the formation of reactive oxygen species and inflammation. We hypothesized that these processes can influence mitochondrial function of the placenta and fetus. OBJECTIVE We investigated the influence of PM₁₀ exposure during pregnancy on the mitochondrial DNA content (mtDNA content) of the placenta and umbilical cord blood. METHODS DNA was extracted from placental tissue (n = 174) and umbilical cord leukocytes (n = 176). Relative mtDNA copy numbers (i.e., mtDNA content) were determined by real-time polymerase chain reaction. Multiple regression models were used to link mtDNA content and in utero exposure to PM₁₀ over various time windows during pregnancy. RESULTS In multivariate-adjusted analysis, a 10-µg/m³ increase in PM₁₀ exposure during the last month of pregnancy was associated with a 16.1% decrease [95% confidence interval (CI): -25.2, -6.0%, p = 0.003] in placental mtDNA content. The corresponding effect size for average PM₁₀ exposure during the third trimester was 17.4% (95% CI: -31.8, -0.1%, p = 0.05). Furthermore, we found that each doubling in residential distance to major roads was associated with an increase in placental mtDNA content of 4.0% (95% CI: 0.4, 7.8%, p = 0.03). No association was found between cord blood mtDNA content and PM₁₀ exposure. CONCLUSIONS Prenatal PM₁₀ exposure was associated with placental mitochondrial alterations, which may both reflect and intensify oxidative stress production. The potential health consequences of decreased placental mtDNA content in early life must be further elucidated.
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Affiliation(s)
- Bram G Janssen
- Centre for Environmental Sciences, Hasselt University, Diepenbeek, Belgium
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346
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Mahrous E, Yang Q, Clarke HJ. Regulation of mitochondrial DNA accumulation during oocyte growth and meiotic maturation in the mouse. Reproduction 2012; 144:177-85. [DOI: 10.1530/rep-12-0113] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Oocytes accumulate an enormous quantity of mitochondrial (mt) DNA, and an insufficient amount of mtDNA may underlie some cases of poor oocyte quality leading to infertility. Little is known, however, about the mechanisms that govern the timing and regulation of mtDNA accumulation during oogenesis. We report, through analysis of the mtDNA content of individual oocytes of the mouse, that mtDNA accumulates steadily during oocyte growth to reach a value of ∼175 000 copies per cell. MtDNA content ceases to increase once oocytes reach full size and remains unchanged during meiotic maturation. To test whether mtDNA accumulation depends on oocyte growth, we inhibited growth in vitro in two ways – by exposing complexes comprising partially grown oocytes enclosed by granulosa cells to a chemical inhibitor of the phosphatidylinositol-3-kinase signaling pathway and by removing the surrounding granulosa cells from partially grown oocytes. Under both conditions, the oocytes fail to grow, but mtDNA accumulation is unaffected, indicating that the two processes can be mechanistically uncoupled. Quantitative analysis of the mRNAs encoding proteins required for mtDNA replication revealed that Polg (Polga) (polymerase-γ, α-subunit), Polg2 (Polgb), and Tfam (transcription factor A, mitochondrial) increase during oocyte growth but then decrease after fully grown oocytes become transcriptionally silent as indicated by the non-surrounded nucleolus-to-surrounded nucleolus transition. Thus, there is a correlation between the decline in the quantity of mRNAs encoding mtDNA replication factors in fully grown oocytes and the arrest of mtDNA accumulation in these cells, suggesting that the two events may be causally linked.
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347
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Thyagarajan B, Wang R, Barcelo H, Koh WP, Yuan JM. Mitochondrial copy number is associated with colorectal cancer risk. Cancer Epidemiol Biomarkers Prev 2012; 21:1574-81. [PMID: 22787200 DOI: 10.1158/1055-9965.epi-12-0138-t] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
BACKGROUND Mitochondria are eukaryotic organelles responsible for energy production. Quantitative changes in human mitochondrial DNA (mtDNA) copy number have been implicated in various cancer types. Data from prospective cohort studies on mtDNA copy number and colorectal cancer risk have been lacking. METHODS We evaluated the association between mtDNA copy number in peripheral blood and colorectal cancer risk in a nested case-control study of 422 colorectal cancer cases (168 cases with pre-diagnostic blood and 254 cases with post-diagnostic blood) and 874 controls who were free of colorectal cancer among participants of the Singapore Chinese Health Study. The relative mtDNA copy number was measured using real-time PCR. Unconditional logistic regression methods were employed to examine the association between mtDNA copy number and colorectal cancer risk. RESULTS There was a U-shaped relationship between the relative mtDNA copy number and colorectal cancer risk. Compared with the 2nd quartile, the OR (95% confidence intervals) for subjects in the lowest and highest quartiles of relative mtDNA copy numbers were 1.81 (1.13-2.89) and 3.40 (2.15-5.36), respectively (P(curvilinearity) <0.0001). This U-shaped relationship was present in both men and women, similar for colon cancer and rectal cancer, and independent of the timing of blood draw with regard to cancer diagnosis. CONCLUSIONS This is the first prospectively designed study to show a U-shaped association between the relative mtDNA copy number and risk of colorectal cancer. IMPACT The findings of the present study support that mtDNA may play a critical role in the colorectal carcinogenesis in humans.
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Affiliation(s)
- Bharat Thyagarajan
- Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, MN 55455, USA.
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348
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Yu M. Circulating cell-free mitochondrial DNA as a novel cancer biomarker: opportunities and challenges. ACTA ACUST UNITED AC 2012; 23:329-32. [PMID: 22775429 DOI: 10.3109/19401736.2012.696625] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The unique characteristics of the mitochondrial genome, such as short length, simple molecular structure, and high copy number, have made monitoring aberrant changes of mitochondrial DNA (mtDNA) quantity an interesting molecular tool for early tumor detection with many advantages over the nuclear genome-based methods. Recently, circulating cell-free (ccf) mtDNA in blood has emerged on the platform as a non-invasive diagnostic and prognostic biomarker for many forms of solid tumors. Accumulating evidence demonstrate that plasma or serum ccf mtDNA levels are significantly different between cancer patients and healthy individuals. Furthermore, quantification of ccf mtDNA levels in circulation may assist in identifying patients from cancer-free healthy population. This minireview attempts to summarize our recent findings in this very promising field of cancer research. The potential technical challenges that we have encountered during the quantitative analysis of ccf mtDNA and mtDNA in general are also briefly discussed. Prospective studies with a larger cohort of patients in various cancer entities are beneficial to precisely define the clinical importance of assessing the ccf mtDNA amount for diagnosing and tracking malignant diseases and their progression.
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Affiliation(s)
- Man Yu
- Ontario Cancer Institute/Princess Margaret Hospital, University Health Network and University of Toronto, Toronto, ON, Canada.
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349
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Wang D, Su LY, Zhang AM, Li YY, Li XA, Chen LL, Long H, Yao YG. Mitochondrial DNA copy number, but not haplogroup, confers a genetic susceptibility to leprosy in Han Chinese from Southwest China. PLoS One 2012; 7:e38848. [PMID: 22719964 PMCID: PMC3377694 DOI: 10.1371/journal.pone.0038848] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2012] [Accepted: 05/11/2012] [Indexed: 12/20/2022] Open
Abstract
Background Leprosy is a chronic infectious disease caused by Mycobacterium leprae, an unculturable pathogen with an exceptionally eroded genome. The high level of inactivation of gene function in M. leprae, including many genes in its metabolic pathways, has led to a dependence on host energy production and nutritional products. We hypothesized that host cellular powerhouse - the mitochondria - may affect host susceptibility to M. leprae and the onset of clinical leprosy, and this may be reflected by mitochondrial DNA (mtDNA) background and mtDNA copy number. Methods We analyzed the mtDNA sequence variation of 534 leprosy patients and 850 matched controls from Yunnan Province and classified each subject by haplogroup. mtDNA copy number, taken to be proportional to mtDNA content, was measured in a subset of these subjects (296 patients and 231 controls) and 12 leprosy patients upon diagnosis. Results Comparison of matrilineal components of the case and control populations revealed no significant difference. However, measurement of mtDNA copy number showed that lepromatous leprosy patients had a significantly higher mtDNA content than controls (P = 0.008). Past medical treatments had no effect on the alteration of mtDNA copy number. Conclusions Our results suggested that mtDNA content, but not haplogroup, affects leprosy and this influence is limited to the clinical subtype of lepromatous leprosy.
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Affiliation(s)
- Dong Wang
- Key Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences & Yunnan Province, Kunming Institute of Zoology, Kunming, Yunnan, China
- Graduate School of the Chinese Academy of Sciences, Beijing, China
| | - Ling-Yan Su
- Key Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences & Yunnan Province, Kunming Institute of Zoology, Kunming, Yunnan, China
- Graduate School of the Chinese Academy of Sciences, Beijing, China
| | - A-Mei Zhang
- Key Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences & Yunnan Province, Kunming Institute of Zoology, Kunming, Yunnan, China
| | - Yu-Ye Li
- The First Affiliated Hospital of Kunming Medical College, Kunming, Yunnan, China
| | - Xiao-An Li
- Yuxi City Center for Disease Control and Prevention, Yuxi, Yunnan, China
| | - Ling-Ling Chen
- The First Affiliated Hospital of Kunming Medical College, Kunming, Yunnan, China
| | - Heng Long
- Wenshan Institute of Dermatology, Wenshan, Yunnan, China
| | - Yong-Gang Yao
- Key Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences & Yunnan Province, Kunming Institute of Zoology, Kunming, Yunnan, China
- * E-mail:
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350
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Kim JH, Lee DC. Mitochondrial DNA copy number in peripheral blood is associated with femoral neck bone mineral density in postmenopausal women. J Rheumatol 2012; 39:1465-72. [PMID: 22589267 DOI: 10.3899/jrheum.111444] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
OBJECTIVE It has been suggested that mitochondrial dysfunction is related to aging and metabolic disorders. Yet there are few studies of the relationship between bone mineral density (BMD) and mitochondrial content in humans. We investigated the relationship between BMD and mitochondrial DNA (mtDNA) copy number in peripheral blood of postmenopausal women. METHODS The study included 146 postmenopausal women. Enrolled subjects were taking no medications and had no disorders that altered bone metabolism. We measured BMD using dual-energy x-ray absorptiometry and leukocyte mtDNA copy number using real-time polymerase chain reaction. Anthropometric evaluations and biochemical tests were performed. RESULTS Patients with osteopenia or osteoporosis had lower mtDNA copy numbers than normal subjects (p < 0.0001). Femoral neck BMD was negatively correlated with age (r = -0.01, p = 0.04) and with serum levels of adiponectin (r = -0.22, p = 0.01) and osteocalcin (r = -0.31, p = 0.0001). Serum levels of 25-OH vitamin D (r = 0.32, p < 0.0001) and mtDNA copy number (r = 0.36, p < 0.0001) were positively correlated with femoral neck BMD. Multiple regression analysis showed that mtDNA copy number (ß = 0.156, p < 0.001) was an independent factor associated with femoral neck BMD after adjustment for age, body mass index, waist circumference, waist-hip ratio, blood pressure, homeostatic model assessment of insulin resistance, high-sensitivity C-reactive protein, adiponectin, osteocalcin, homocysteine, lipid profiles, 25-OH vitamin D, and regular exercise. mtDNA copy number was not related to lumbar BMD. CONCLUSION Low mtDNA content in peripheral blood is related to decreased femoral neck BMD in postmenopausal women. Our findings suggest that mitochondrial dysfunction may be a potential pathophysiologic mechanism of osteoporosis in postmenopausal women.
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Affiliation(s)
- Jung-Ha Kim
- Department of Family Medicine, Chung-Ang University Healthcare Center, Korea
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