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Mishmar D, Levin R, Naeem MM, Sondheimer N. Higher Order Organization of the mtDNA: Beyond Mitochondrial Transcription Factor A. Front Genet 2019; 10:1285. [PMID: 31998357 PMCID: PMC6961661 DOI: 10.3389/fgene.2019.01285] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Accepted: 11/21/2019] [Indexed: 01/09/2023] Open
Abstract
The higher order organization of eukaryotic and prokaryotic genomes is pivotal in the regulation of gene expression. Specifically, chromatin accessibility in eukaryotes and nucleoid accessibility in bacteria are regulated by a cohort of proteins to alter gene expression in response to diverse physiological conditions. By contrast, prior studies have suggested that the mitochondrial genome (mtDNA) is coated solely by mitochondrial transcription factor A (TFAM), whose increased cellular concentration was proposed to be the major determinant of mtDNA packaging in the mitochondrial nucleoid. Nevertheless, recent analysis of DNase-seq and ATAC-seq experiments from multiple human and mouse samples suggest gradual increase in mtDNA occupancy during the course of embryonic development to generate a conserved footprinting pattern which correlate with sites that have low TFAM occupancy in vivo (ChIP-seq) and tend to adopt G-quadruplex structures. These findings, along with recent identification of mtDNA binding by known modulators of chromatin accessibility such as MOF, suggest that mtDNA higher order organization is generated by cross talk with the nuclear regulatory system, may have a role in mtDNA regulation, and is more complex than once thought.
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Affiliation(s)
- Dan Mishmar
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Rotem Levin
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Mansur M Naeem
- Institute of Medical Sciences and the Department of Paediatrics, The University of Toronto, Toronto, ON, Canada
| | - Neal Sondheimer
- Institute of Medical Sciences and the Department of Paediatrics, The University of Toronto, Toronto, ON, Canada
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Phillips AF, Millet AR, Tigano M, Dubois SM, Crimmins H, Babin L, Charpentier M, Piganeau M, Brunet E, Sfeir A. Single-Molecule Analysis of mtDNA Replication Uncovers the Basis of the Common Deletion. Mol Cell 2017; 65:527-538.e6. [PMID: 28111015 DOI: 10.1016/j.molcel.2016.12.014] [Citation(s) in RCA: 91] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2016] [Revised: 10/04/2016] [Accepted: 12/16/2016] [Indexed: 11/30/2022]
Abstract
Mutations in mtDNA lead to muscular and neurological diseases and are linked to aging. The most frequent aberrancy is the "common deletion" that involves a 4,977-bp region flanked by 13-bp repeats. To investigate the basis of this deletion, we developed a single-molecule mtDNA combing method. The analysis of replicating mtDNA molecules provided in vivo evidence in support of the asymmetric mode of replication. Furthermore, we observed frequent fork stalling at the junction of the common deletion, suggesting that impaired replication triggers the formation of this toxic lesion. In parallel experiments, we employed mito-TALENs to induce breaks in distinct loci of the mitochondrial genome and found that breaks adjacent to the 5' repeat trigger the common deletion. Interestingly, this process was mediated by the mitochondrial replisome independent of canonical DSB repair. Altogether, our data underscore a unique replication-dependent repair pathway that leads to the mitochondrial common deletion.
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Affiliation(s)
- Aaron F Phillips
- Skirball Institute of Biomolecular Medicine, Department of Cell Biology, NYU School of Medicine, New York, NY 10016, USA
| | - Armêl R Millet
- Structure et Instabilité des Génomes, Muséum National d'Histoire Naturelle, INSERM U 1154, CNRS UMR 7196, 75005 Paris, France; Genome Dynamics in the Immune System Laboratory, INSERM, UMR 1163, Institut Imagine, 75015 Paris, France
| | - Marco Tigano
- Skirball Institute of Biomolecular Medicine, Department of Cell Biology, NYU School of Medicine, New York, NY 10016, USA
| | - Sonia M Dubois
- Structure et Instabilité des Génomes, Muséum National d'Histoire Naturelle, INSERM U 1154, CNRS UMR 7196, 75005 Paris, France
| | - Hannah Crimmins
- Skirball Institute of Biomolecular Medicine, Department of Cell Biology, NYU School of Medicine, New York, NY 10016, USA
| | - Loelia Babin
- Structure et Instabilité des Génomes, Muséum National d'Histoire Naturelle, INSERM U 1154, CNRS UMR 7196, 75005 Paris, France; Genome Dynamics in the Immune System Laboratory, INSERM, UMR 1163, Institut Imagine, 75015 Paris, France
| | - Marine Charpentier
- Structure et Instabilité des Génomes, Muséum National d'Histoire Naturelle, INSERM U 1154, CNRS UMR 7196, 75005 Paris, France
| | - Marion Piganeau
- Structure et Instabilité des Génomes, Muséum National d'Histoire Naturelle, INSERM U 1154, CNRS UMR 7196, 75005 Paris, France
| | - Erika Brunet
- Structure et Instabilité des Génomes, Muséum National d'Histoire Naturelle, INSERM U 1154, CNRS UMR 7196, 75005 Paris, France; Genome Dynamics in the Immune System Laboratory, INSERM, UMR 1163, Institut Imagine, 75015 Paris, France.
| | - Agnel Sfeir
- Skirball Institute of Biomolecular Medicine, Department of Cell Biology, NYU School of Medicine, New York, NY 10016, USA.
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Oliveira PH, da Silva CL, Cabral JMS. An appraisal of human mitochondrial DNA instability: new insights into the role of non-canonical DNA structures and sequence motifs. PLoS One 2013; 8:e59907. [PMID: 23555828 PMCID: PMC3612095 DOI: 10.1371/journal.pone.0059907] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2013] [Accepted: 02/20/2013] [Indexed: 01/29/2023] Open
Abstract
Mitochondrial DNA (mtDNA) deletion mutations are frequently observed in aged postmitotic tissues and are the cause of a wide range of human disorders. Presently, the molecular bases underlying mtDNA deletion formation remain a matter of intense debate, and it is commonly accepted that several mechanisms contribute to the spectra of mutations in the mitochondrial genome. In this work we performed an extensive screening of human mtDNA deletions and evaluated the association between breakpoint density and presence of non-canonical DNA elements and over-represented sequence motifs. Our observations support the involvement of helix-distorting intrinsically curved regions and long G-tetrads in eliciting instability events. In addition, higher breakpoint densities were consistently observed within GC-skewed regions and in the close vicinity of the degenerate sequence motif YMMYMNNMMHM. A parallelism is also established with hot spot motifs previously identified in the nuclear genome, as well as with the minimal binding site for the mitochondrial transcription termination factor mTERF. This study extends the current knowledge on the mechanisms driving mitochondrial rearrangements and opens up exciting avenues for further research.
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Affiliation(s)
- Pedro H Oliveira
- Department of Bioengineering and Institute for Biotechnology and Bioengineering, Instituto Superior Técnico, Lisbon, Portugal.
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Damas J, Carneiro J, Gonçalves J, Stewart JB, Samuels DC, Amorim A, Pereira F. Mitochondrial DNA deletions are associated with non-B DNA conformations. Nucleic Acids Res 2012; 40:7606-21. [PMID: 22661583 PMCID: PMC3439893 DOI: 10.1093/nar/gks500] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Mitochondrial DNA (mtDNA) deletions are a primary cause of mitochondrial disease and are believed to contribute to the aging process and to various neurodegenerative diseases. Despite strong observational and experimental evidence, the molecular basis of the deletion process remains obscure. In this study, we test the hypothesis that the primary cause of mtDNA vulnerability to breakage resides in the formation of non-B DNA conformations, namely hairpin, cruciform and cloverleaf-like elements. Using the largest database of human mtDNA deletions built thus far (753 different cases), we show that site-specific breakage hotspots exist in the mtDNA. Furthermore, we discover that the most frequent deletion breakpoints occur within or near predicted structures, a result that is supported by data from transgenic mice with mitochondrial disease. There is also a significant association between the folding energy of an mtDNA region and the number of breakpoints that it harbours. In particular, two clusters of hairpins (near the D-loop 3′-terminus and the L-strand origin of replication) are hotspots for mtDNA breakage. Consistent with our hypothesis, the highest number of 5′- and 3′-breakpoints per base is found in the highly structured tRNA genes. Overall, the data presented in this study suggest that non-B DNA conformations are a key element of the mtDNA deletion process.
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Affiliation(s)
- Joana Damas
- Institute of Molecular Pathology and Immunology, University of Porto (IPATIMUP), Rua Dr Roberto Frias s/n, 4200-465 Porto, Portugal
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Todorov IN, Todorov GI. Multifactorial nature of high frequency of mitochondrial DNA mutations in somatic mammalian cells. BIOCHEMISTRY (MOSCOW) 2009; 74:962-70. [DOI: 10.1134/s000629790909003x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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Ji F, Pierre Z, Liu S, Hwang BJ, Hill HZ, Hubbard K, Steinberg M. Novel mitochondrial deletions in human epithelial cells irradiated with an FS20 ultraviolet light source in vitro. J Photochem Photobiol A Chem 2006. [DOI: 10.1016/j.jphotochem.2006.04.037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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7
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Coon KD, Valla J, Szelinger S, Schneider LE, Niedzielko TL, Brown KM, Pearson JV, Halperin R, Dunckley T, Papassotiropoulos A, Caselli RJ, Reiman EM, Stephan DA. Quantitation of heteroplasmy of mtDNA sequence variants identified in a population of AD patients and controls by array-based resequencing. Mitochondrion 2006; 6:194-210. [PMID: 16920408 DOI: 10.1016/j.mito.2006.07.002] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2006] [Revised: 06/30/2006] [Accepted: 07/13/2006] [Indexed: 01/03/2023]
Abstract
The role of mitochondrial dysfunction in the pathogenesis of Alzheimer's disease (AD) has been well documented. Though evidence for the role of mitochondria in AD seems incontrovertible, the impact of mitochondrial DNA (mtDNA) mutations in AD etiology remains controversial. Though mutations in mitochondrially encoded genes have repeatedly been implicated in the pathogenesis of AD, many of these studies have been plagued by lack of replication as well as potential contamination of nuclear-encoded mitochondrial pseudogenes. To assess the role of mtDNA mutations in the pathogenesis of AD, while avoiding the pitfalls of nuclear-encoded mitochondrial pseudogenes encountered in previous investigations and showcasing the benefits of a novel resequencing technology, we sequenced the entire coding region (15,452 bp) of mtDNA from 19 extremely well-characterized AD patients and 18 age-matched, unaffected controls utilizing a new, reliable, high-throughput array-based resequencing technique, the Human MitoChip. High-throughput, array-based DNA resequencing of the entire mtDNA coding region from platelets of 37 subjects revealed the presence of 208 loci displaying a total of 917 sequence variants. There were no statistically significant differences in overall mutational burden between cases and controls, however, 265 independent sites of statistically significant change between cases and controls were identified. Changed sites were found in genes associated with complexes I (30.2%), III (3.0%), IV (33.2%), and V (9.1%) as well as tRNA (10.6%) and rRNA (14.0%). Despite their statistical significance, the subtle nature of the observed changes makes it difficult to determine whether they represent true functional variants involved in AD etiology or merely naturally occurring dissimilarity. Regardless, this study demonstrates the tremendous value of this novel mtDNA resequencing platform, which avoids the pitfalls of erroneously amplifying nuclear-encoded mtDNA pseudogenes, and our proposed analysis paradigm, which utilizes the availability of raw signal intensity values for each of the four potential alleles to facilitate quantitative estimates of mtDNA heteroplasmy. This information provides a potential new target for burgeoning diagnostics and therapeutics that could truly assist those suffering from this devastating disorder.
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Affiliation(s)
- Keith D Coon
- Neurogenomics Division, Translational Genomics Research Institute, Phoenix, AZ 85004, USA
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Harbottle A, Birch-Machin MA. Real-time PCR analysis of a 3895 bp mitochondrial DNA deletion in nonmelanoma skin cancer and its use as a quantitative marker for sunlight exposure in human skin. Br J Cancer 2006; 94:1887-93. [PMID: 16721366 PMCID: PMC2361359 DOI: 10.1038/sj.bjc.6603178] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Previous findings from our own laboratory have shown that the frequency of occurrence (i.e. the simple presence or absence) of the 3895 bp mitochondrial DNA deletion is increased with increasing sun exposure. The present study has significantly extended this work by developing, validating and then using a quantitative real-time PCR assay to investigate for the first time the actual level (as opposed to the frequency of occurrence) of the 3895 bp deletion in human skin from different sun-exposed body sites and tumours from nonmelanoma skin cancer patients. We investigated the 3895 bp deletion in 104 age-matched split human skin samples taken from various sun-exposed sites defined as usually exposed (n=60) and occasionally exposed (n=44) when outdoors. The results clearly show an increased level of the 3895 bp deletion with increasing sun exposure. Specifically, there was a significantly higher level of the deletion in the usually sun-exposed compared to the occasionally sun-exposed skin (P=0.0009 for dermis, P=0.008 for epidermis; two-tailed t-test). Our study has also extended previous findings by showing that the level of the 3895 bp deletion is significantly higher in the dermis compared with the epidermis both in the occasionally sun-exposed samples (P=0.0143) and in the usually sun-exposed skin. (P=0.0007).
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Affiliation(s)
- A Harbottle
- Dermatological Sciences, School of Clinical and Laboratory Sciences, University of Newcastle, Newcastle upon Tyne NE2 4HH, UK
| | - M A Birch-Machin
- Dermatological Sciences, School of Clinical and Laboratory Sciences, University of Newcastle, Newcastle upon Tyne NE2 4HH, UK
- E-mail:
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Bannikova S, Zorov DB, Shoeman RL, Tolstonog GV, Traub P. Stability and Association with the Cytomatrix of Mitochondrial DNA in Spontaneously Immortalized Mouse Embryo Fibroblasts Containing or Lacking the Intermediate Filament Protein Vimentin. DNA Cell Biol 2005; 24:710-35. [PMID: 16274293 DOI: 10.1089/dna.2005.24.710] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
To extend previous observations demonstrating differences in number, morphology, and activity of mitochondria in spontaneously immortalized vim(+) and vim(-) fibroblasts derived from wild-type and vimentin knockout mice, some structural and functional aspects of mitochondrial genome performance and integrity in both types of cells were investigated. Primary Vim(+/+) and Vim(-/-) fibroblasts, which escaped terminal differentiation by immortalization were characterized by an almost twofold lower mtDNA content in comparison to that of their primary precursor cells, whereby the average mtDNA copy number in two clones of vim(+) cells was lower by a factor of 0.6 than that in four clones of vim(-) cells. However, during serial subcultivation up to high passage numbers, the vim(+) and vim() fibroblasts increased their mtDNA copy number 1.5- and 2.5-fold, respectively. While early-passage cells of the vim(+) and vim(-) fibroblast clones differed only slightly in the ratio between mtDNA content and mitochondrial mass represented by mtHSP70 protein, after ca. 300 population doublings the average mtDNA/mtmass ratio in the vim(+) and vim() cells was increased by a factor of 2 and 4.5, respectively. During subcultivation, both types of cells acquired the fully transformed phenotype. These findings suggest that cytoskeletal vimentin filaments exert a strong influence on the mechanisms controlling mtDNA copy number during serial subcultivation of immortalized mouse embryo fibroblasts, and that vimentin deficiency causes a disproportionately enhanced mtDNA content in high-passage vim(-) fibroblasts. Such a role of vimentin filaments was supported by the stronger retention potential for mtDNA and mtDNA polymerase (gamma) detected in vim(+) fibroblasts by Triton X-100 extraction of mitochondria and agaroseembedded cells. Moreover, although the vim(+) and vim(-) fibroblasts were equally active in generating free radicals, the vim(-) cells exhibited higher levels of immunologically detectable 8-oxoG and mismatch repair proteins MSH2 and MLH1 in their mitochondria. Because in vim(-) fibroblasts only one point mutation was detected in the mtDNA D-loop control region, these cells are apparently able to efficiently remove oxidatively damaged nucleobases. On the other hand, a number of large-scale mtDNA deletions were found in high-passage vim(-) fibroblasts, but not in low-passage vim(-) cells and vim(+) cells of both low and high passage. Large mtDNA deletions were also induced in young vim(-) fibroblasts by treatment with the DNA intercalator ethidium bromide, whereas no such deletions were found after treatment of vim(+) cells. These results indicate that in immortalized vim(-) fibroblasts the mitochondrial genome is prone to large-scale rearrangements, probably due to insufficient control of mtDNA repair and recombination processes in the absence of vimentin.
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Zhu W, Qin W, Sauter ER. Large-scale mitochondrial DNA deletion mutations and nuclear genome instability in human breast cancer. ACTA ACUST UNITED AC 2004; 28:119-26. [PMID: 15068836 DOI: 10.1016/j.cdp.2003.11.008] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2003] [Accepted: 12/30/2003] [Indexed: 10/26/2022]
Abstract
Deletion mutations in mitochondrial (mt) DNA (mtDNA) as well as microsatellite instability (MSI) and loss of heterozygosity (LOH) in nuclear DNA (nDNA) exist in human cancer. We determined if: (1) large-scale mtDNA deletion mutations were present in cancerous and not in normal breast tissue, and (2) combining mt- and nDNA findings would provide complementary information to identify breast cancer. Thirty-nine matched breast cancer/histologically normal and 23 "true" normal tissue samples from women without breast cancer were microdissected and DNA extracted. 4977, approximately 3938, approximately 4388 and approximately 4576bp deletions were observed, with the 4576bp deletion being present in 0% of true normal, 13% of histologically normal specimens from a cancerous breast and 77% of breast cancers. The other three deletions were not specific to a breast containing cancer. LOH was found in 66.7% and MSI in 38.5% of samples. 38/39 (97.4%) tumors had at least one nDNA or 4576bp mtDNA alteration, suggesting that mt- and nDNA analysis provides complementary information in breast cancer detection. The 4576bp deletion appears to indicate cancer in the breast. The higher mtDNA copy number in cancer coupled with a mtDNA deletion mutation which appears specific for breasts which contain cancer may prove to be a good target to screen for cancer in the breast, including specimens of low and/or mixed cellularity.
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Affiliation(s)
- Weizhu Zhu
- Ellis Fischel Cancer Center and Department of Surgery, University of Missouri, M588 One Hospital Drive, Columbia, MO 65212, USA
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11
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Affiliation(s)
- Yau-Huei Wei
- Department of Biochemistry, Center for Cellular and Molecular Biology, National Yang-Ming University, Taipei, Taiwan, Republic of China
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12
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von Wurmb-Schwark N, Schwark T, Meissner C, Oehmichen M. Mitochondrial mutagenesis in the brain in forensic and pathological research. Leg Med (Tokyo) 2003; 5:1-6. [PMID: 12935643 DOI: 10.1016/s1344-6223(03)00003-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Accumulation of alterations to the mitochondrial DNA (mtDNA) would be expected to significantly impair the bioenergetic function of mitochondria in the affected host cells. Many of these changes have been associated with several specific diseases and the process of aging. These mutations may be the result of mitochondrial oxidative stress, which is increased with age of individuals and specific degenerative diseases. Our aim with this review is to summarize the recent literature on the occurrence of mtDNA alterations and its possible relation to age-depending degenerative processes with special regards to the brain. Additionally, we show how these alterations could be used in fields of pathology and forensic medicine.
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Wei YH, Lee HC. Oxidative stress, mitochondrial DNA mutation, and impairment of antioxidant enzymes in aging. Exp Biol Med (Maywood) 2002; 227:671-82. [PMID: 12324649 DOI: 10.1177/153537020222700901] [Citation(s) in RCA: 383] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Mitochondria do not only produce less ATP, but they also increase the production of reactive oxygen species (ROS) as by-products of aerobic metabolism in the aging tissues of the human and animals. It is now generally accepted that aging-associated respiratory function decline can result in enhanced production of ROS in mitochondria. Moreover, the activities of free radical-scavenging enzymes are altered in the aging process. The concurrent age-related changes of these two systems result in the elevation of oxidative stress in aging tissues. Within a certain concentration range, ROS may induce stress response of the cells by altering expression of respiratory genes to uphold the energy metabolism to rescue the cell. However, beyond the threshold, ROS may cause a wide spectrum of oxidative damage to various cellular components to result in cell death or elicit apoptosis by induction of mitochondrial membrane permeability transition and release of apoptogenic factors such as cytochrome c. Moreover, oxidative damage and large-scale deletion and duplication of mitochondrial DNA (mtDNA) have been found to increase with age in various tissues of the human. Mitochondria act like a biosensor of oxidative stress and they enable cell to undergo changes in aging and age-related diseases. On the other hand, it has recently been demonstrated that impairment in mitochondrial respiration and oxidative phosphorylation elicits an increase in oxidative stress and causes a host of mtDNA rearrangements and deletions. Here, we review work done in the past few years to support our view that oxidative stress and oxidative damage are a result of concurrent accumulation of mtDNA mutations and defective antioxidant enzymes in human aging.
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Affiliation(s)
- Yau-Huei Wei
- Department of Biochemistry and Center for Cellular and Molecular Biology, National Yang-Ming University, Taipei 112, Taiwan.
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14
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Lewis PD, Baxter P, Paul Griffiths A, Parry JM, Skibinski DO. Detection of damage to the mitochondrial genome in the oncocytic cells of Warthin's tumour. J Pathol 2000; 191:274-81. [PMID: 10878549 DOI: 10.1002/1096-9896(2000)9999:9999<::aid-path634>3.0.co;2-u] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Warthin's tumour of the salivary glands is composed of oncocytic cells containing excessive numbers of mitochondria which show frequent structural abnormalities and reduced metabolic function. Recent evidence of a strong association between cigarette smoking and the occurrence of Warthin's tumour prompted this study, to look for evidence of damage to mitochondrial DNA (mtDNA) that could be the result of an increase in oxidative stress; two-colour fluorescence in situ hybridization (FISH) was developed to show the distribution of mitochondria with deleted mtDNA in paraffin wax-embedded material. Approximately 10% of mtDNA bears the 'common' 4977 bp deletion. Using the polymerase chain reaction (PCR), the 4977 bp deletion was further quantified, in Warthin's tumour and age-matched normal parotid control tissue. Whilst the deletion was present in all parotid tissue, its presence was significantly higher in oncocytic tumour cells. In a small number of controls, there was a trend towards higher concentrations of the deletion in smokers.
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Affiliation(s)
- P D Lewis
- School of Biological Sciences, University of Wales Swansea, UK.
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15
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Wei YH, Lu CY, Lee HC, Pang CY, Ma YS. Oxidative damage and mutation to mitochondrial DNA and age-dependent decline of mitochondrial respiratory function. Ann N Y Acad Sci 1998; 854:155-70. [PMID: 9928427 DOI: 10.1111/j.1749-6632.1998.tb09899.x] [Citation(s) in RCA: 171] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Mitochondrial respiration and oxidative phosphorylation are gradually uncoupled, and the activities of the respiratory enzymes are concomitantly decreased in various human tissues upon aging. An immediate consequence of such gradual impairment of the respiratory function is the increase in the production of the reactive oxygen species (ROS) and free radicals in the mitochondria through the increased electron leak of the electron transport chain. Moreover, the intracellular levels of antioxidants and free radical scavenging enzymes are gradually altered. These two compounding factors lead to an age-dependent increase in the fraction of the ROS and free radical that may escape the defense mechanism and cause oxidative damage to various biomolecules in tissue cells. A growing body of evidence has established that the levels of ROS and oxidative damage to lipids, proteins, and nucleic acids are significantly increased with age in animal and human tissues. The mitochondrial DNA (mtDNA), although not protected by histones or DNA-binding proteins, is susceptible to oxidative damage by the ever-increasing levels of ROS and free radicals in the mitochondrial matrix. In the past few years, oxidative modification (formation of 8-hydroxy-2'-deoxyguanosine) and large-scale deletion and point mutation of mtDNA have been found to increase exponentially with age in various human tissues. The respiratory enzymes containing the mutant mtDNA-encoded defective protein subunits inevitably exhibit impaired respiratory function and thereby increase electron leak and ROS production, which in turn elevates the oxidative stress and oxidative damage of the mitochondria. This vicious cycle operates in different tissue cells at different rates and thereby leads to the differential accumulation of mutation and oxidative damage to mtDNA in human aging. This may also play some role in the pathogenesis of degenerative diseases and the age-dependent progression of the clinical course of mitochondrial diseases.
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Affiliation(s)
- Y H Wei
- Department of Biochemistry, School of Life Science, National Yang-Ming University, Taipei, Taiwan, Republic of China.
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