Science.gov

Sample records for mitochondrial dna transit

  1. Mitochondrial DNA.

    ERIC Educational Resources Information Center

    Wright, Russell G.; Bottino, Paul J.

    1986-01-01

    Provides background information for teachers on mitochondrial DNA, pointing out that it may have once been a free-living organism. Includes a ready-to-duplicate exercise titled "Using Microchondrial DNA to Measure Evolutionary Distance." (JN)

  2. Mitochondrial DNA.

    ERIC Educational Resources Information Center

    Wright, Russell G.; Bottino, Paul J.

    1986-01-01

    Provides background information for teachers on mitochondrial DNA, pointing out that it may have once been a free-living organism. Includes a ready-to-duplicate exercise titled "Using Microchondrial DNA to Measure Evolutionary Distance." (JN)

  3. What Is Mitochondrial DNA?

    MedlinePlus

    ... DNA What is mitochondrial DNA? What is mitochondrial DNA? Although most DNA is packaged in chromosomes within ... proteins. For more information about mitochondria and mitochondrial DNA: Molecular Expressions, a web site from the Florida ...

  4. Induction of mitochondrial permeability transition by the DNA-intercalating cationic dye ethidium bromide.

    PubMed

    García, Noemí; Hernández-Esquivel, Luz; Zazueta, Cecilia; Martínez-Abundis, Eduardo; Pavón, Natalia; Chávez, Edmundo

    2009-12-01

    This work shows that the DNA cationic probe, ethidium bromide (EtBr), induces the transition from selective to non-selective mitochondrial permeability. This statement is based on the findings, indicating: (i) EtBr induced the release of accumulated Ca(2+) through a mechanism sensitive to cyclosporin A and octylguanidine; (ii) EtBr induced the release of cytochrome c and (iii) EtBr induced mitochondrial swelling. Interestingly, mersalyl inhibited, in a non-competitive fashion, EtBr uptake, which would indicate that the uptake may be carried out through a protein membrane system. This work also shows that the effect of the dye on permeability transition was stimulated by carboxyatractyloside. Taking into account the facts that EtBr inhibited the ADP exchange reaction and increased the binding of the fluorescent probe eosin-5-maleimide to adenine nucleotide translocase, it is tempting to assume a possible interaction between EtBr and the ADP/ATP carrier.

  5. Mitochondrial permeability transition increases reactive oxygen species production and induces DNA fragmentation in human spermatozoa.

    PubMed

    Treulen, Favián; Uribe, Pamela; Boguen, Rodrigo; Villegas, Juana V

    2015-04-01

    Does mitochondrial permeability transition (MPT) induced by calcium overload cause reactive oxygen species (ROS) production and DNA fragmentation in human spermatozoa? Studies conducted in vitro suggest that in human spermatozoa, MPT occurs in response to intracellular calcium increase and is associated with mitochondrial membrane potential (ΔΨm) dissipation, increased ROS production and DNA fragmentation. Oxidative stress is a major cause of defective sperm function in male infertility. By opening calcium-dependent pores in the inner mitochondrial membrane (IMM), MPT causes, among other things, increased ROS production and ΔΨm dissipation in somatic cells. MPT as a mechanism for generating oxidative stress and DNA fragmentation in human spermatozoa has not been studied. Human sperm were exposed to ionomycin for 1.5 h (n = 8) followed by analysis of sperm IMM permeability, ΔΨm, ROS production and DNA fragmentation. To evaluate the MPT in sperm cells, the calcein-AM and cobalt chloride method was used. The ΔΨm was evaluated by JC-1 staining, intracellular ROS production was evaluated with dihydroethidium and DNA fragmentation was evaluated by a modified TUNEL assay. Measurements were performed by fluorescence microscopy, confocal laser microscopy and flow cytometry. Decreased calcein fluorescence after treatment with ionomycin (P < 0.05) suggests the opening of pores in the sperm IMM and this was accompanied by ΔΨm dissipation, increased ROS production and DNA fragmentation. ROS production occurred prior to the decrease in ΔΨm. The study was carried out in vitro using motile sperm from healthy donors; tests on sperm from infertile patients were not carried out. We propose that the MPT, due to pores opening in sperm IMM, is an important mechanism of increased ROS and DNA fragmentation. Therefore, agents that modulate the opening of these pores might contribute to the prevention of damage by oxidative stress in human spermatozoa. This study was funded by

  6. Complete mitochondrial DNA genome sequences show that modern birds are not descended from transitional shorebirds.

    PubMed Central

    Paton, Tara; Haddrath, Oliver; Baker, Allan J

    2002-01-01

    To test the hypothesis put forward by Feduccia of the origin of modern birds from transitional birds, we sequenced the first two complete mitochondrial genomes of shorebirds (ruddy turnstone and blackish oystercatcher) and compared their sequences with those of already published avian genomes. When corrected for rate heterogeneity across sites and non-homogeneous nucleotide compositions among lineages in maximum likelihood (ML), the optimal tree places palaeognath birds as sister to the neognaths including shorebirds. This optimal topology is a re-rooting of recently published ordinal-level avian trees derived from mitochondrial sequences. Using a penalized likelihood (PL) rate-smoothing process in conjunction with dates estimated from fossils, we show that the basal splits in the bird tree are much older than the Cretaceous-Tertiary (K-T) boundary, reinforcing previous molecular studies that rejected the derivation of modern birds from transitional shorebirds. Our mean estimate for the origin of modern birds at about 123 million years ago (Myr ago) is quite close to recent estimates using both nuclear and mitochondrial genes, and supports theories of continental break-up as a driving force in avian diversification. Not only did many modern orders of birds originate well before the K-T boundary, but the radiation of major clades occurred over an extended period of at least 40 Myr ago, thus also falsifying Feduccia's rapid radiation scenario following a K-T bottleneck. PMID:11958716

  7. Transcription of mitochondrial DNA.

    PubMed

    Tabak, H F; Grivell, L A; Borst, P

    1983-01-01

    While mitochondrial DNA (mtDNA) is the simplest DNA in nature, coding for rRNAs and tRNAs, results of DNA sequence, and transcript analysis have demonstrated that both the synthesis and processing of mitochondrial RNAs involve remarkably intricate events. At one extreme, genes in animal mtDNAs are tightly packed, both DNA strands are completely transcribed (symmetric transcription), and the appearance of specific mRNAs is entirely dependent on processing at sites signalled by the sequences of the tRNAs, which abut virtually every gene. At the other extreme, gene organization in yeast (Saccharomyces) is anything but compact, with long stretches of AT-rich DNA interspaced between coding sequences and no obvious logic to the order of genes. Transcription is asymmetric and several RNAs are initiated de novo. Nevertheless, extensive RNA processing occurs due largely to the presence of split genes. RNA splicing is complex, is controlled by both mitochondrial and nuclear genes, and in some cases is accompanied by the formation of RNAs that behave as covalently closed circles. The present article reviews current knowledge of mitochondrial transcription and RNA processing in relation to possible mechanisms for the regulation of mitochondrial gene expression.

  8. Mitochondrial DNA polymorphism in mitochondrial myopathy.

    PubMed

    Holt, I J; Harding, A E; Morgan-Hughes, J A

    1988-05-01

    In order to test the hypothesis that mitochondrial myopathy may be caused by mutation of the mitochondrial (mt) genome, restriction fragment length polymorphism in leucocyte mt DNA has been studied in 38 patients with mitochondrial myopathy, 44 of their unaffected matrilineal relatives, and 35 normal control subjects. Previously unreported mt DNA polymorphisms were identified in both patients and controls. No differences in restriction fragment patterns were observed between affected and unaffected individuals in the same maternal line, and there was no evidence of major deletion of mt DNA in patients. This study provides no positive evidence of mitochondrial inheritance in mitochondrial myopathy, but this has not been excluded.

  9. Environmental mutagens induced transversions but not transitions in regulatory region of mitochondrial DNA.

    PubMed

    Partridge, Michael A; Huang, Sarah X L; Kibriya, Muhammad G; Ahsan, Habibul; Davidson, Mercy M; Hei, Tom K

    2009-01-01

    One of the long-term objectives of the research in our laboratory was to determine whether mitochondrial DNA (mtDNA) mutations were generated in cell lines exposed to a variety of known mutagens. Many of these mutagens are known to increase oxidative stress in the cell, and one potential outcome of this would be an increased incidence of point mutations in mtDNA. Recently, there has been some controversy regarding the validity of point mutations in the regulatory region of mtDNA as a predictive or causative marker for carcinogenesis. Studies were undertaken to assess whether nuclear mutagens such as arsenic (As), asbestos, and ultraviolet (UV) and gamma-radiation, induced both heteroplasmic and homoplasmic point mutations in mtDNA. A direct sequencing approach was used to reduce the occurrence of experimental errors and cross-checked all base changes with databases of known polymorphisms. Our results showed that, while base changes did occur, there was no marked difference between the number of changes in treated and untreated cells. Furthermore, in human lymphocyte samples from subjects exposed to As, most of these base changes were previously reported. Interestingly, there was an increase in the number of transversions (purine ( pyrimidine) in smokers from a human population study, but as with the findings in cell culture samples, there was no difference in the total number of base changes. Data suggest that only a change in the number of rare transversions would be indicative of an increase in point mutations in mtDNA after exposure to mutagens.

  10. Mitochondrial DNA transit between West Asia and North Africa inferred from U6 phylogeography

    PubMed Central

    Maca-Meyer, Nicole; González, Ana M; Pestano, José; Flores, Carlos; Larruga, José M; Cabrera, Vicente M

    2003-01-01

    Background World-wide phylogeographic distribution of human complete mitochondrial DNA sequences suggested a West Asian origin for the autochthonous North African lineage U6. We report here a more detailed analysis of this lineage, unraveling successive expansions that affected not only Africa but neighboring regions such as the Near East, the Iberian Peninsula and the Canary Islands. Results Divergence times, geographic origin and expansions of the U6 mitochondrial DNA clade, have been deduced from the analysis of 14 complete U6 sequences, and 56 different haplotypes, characterized by hypervariable segment sequences and RFLPs. Conclusions The most probable origin of the proto-U6 lineage was the Near East. Around 30,000 years ago it spread to North Africa where it represents a signature of regional continuity. Subgroup U6a reflects the first African expansion from the Maghrib returning to the east in Paleolithic times. Derivative clade U6a1 signals a posterior movement from East Africa back to the Maghrib and the Near East. This migration coincides with the probable Afroasiatic linguistic expansion. U6b and U6c clades, restricted to West Africa, had more localized expansions. U6b probably reached the Iberian Peninsula during the Capsian diffusion in North Africa. Two autochthonous derivatives of these clades (U6b1 and U6c1) indicate the arrival of North African settlers to the Canarian Archipelago in prehistoric times, most probably due to the Saharan desiccation. The absence of these Canarian lineages nowadays in Africa suggests important demographic movements in the western area of this Continent. PMID:14563219

  11. Human Mitochondrial DNA Replication

    PubMed Central

    Holt, Ian J.; Reyes, Aurelio

    2012-01-01

    Elucidation of the process of DNA replication in mitochondria is in its infancy. For many years, maintenance of the mitochondrial genome was regarded as greatly simplified compared to the nucleus. Mammalian mitochondria were reported to lack all DNA repair systems, to eschew DNA recombination, and to possess but a single DNA polymerase, polymerase γ. Polγ was said to replicate mitochondrial DNA exclusively via one mechanism, involving only two priming events and a handful of proteins. In this “strand-displacement model,” leading strand DNA synthesis begins at a specific site and advances approximately two-thirds of the way around the molecule before DNA synthesis is initiated on the “lagging” strand. Although the displaced strand was long-held to be coated with protein, RNA has more recently been proposed in its place. Furthermore, mitochondrial DNA molecules with all the features of products of conventional bidirectional replication have been documented, suggesting that the process and regulation of replication in mitochondria is complex, as befits a genome that is a core factor in human health and longevity. PMID:23143808

  12. Mitochondrial oxidative stress and mitochondrial DNA.

    PubMed

    Kang, Dongchon; Hamasaki, Naotaka

    2003-10-01

    Mitochondria produce reactive oxygen species (ROS) under physiological conditions in association with activity of the respiratory chain in aerobic ATP production. The production of ROS is essentially a function of O2 consumption. Hence, increased mitochondrial activity per se can be an oxidative stress to cells. Furthermore, production of ROS is markedly enhanced in many pathological conditions in which the respiratory chain is impaired. Because mitochondrial DNA, which is essential for execution of normal oxidative phosphorylation, is located in proximity to the ROS-generating respiratory chain, it is more oxidatively damaged than is nuclear DNA. Cumulative damage of mitochondrial DNA is implicated in the aging process and in the progression of such common diseases as diabetes, cancer, and heart failure.

  13. Phylogenetic relationships among phrynosomatid lizards as inferred from mitochondrial ribosomal DNA sequences: substitutional bias and information content of transitions relative to transversions.

    PubMed

    Reeder, T W

    1995-06-01

    The phylogenetic relationships among 40 species, representing all genera, within the North American lizard family Phrynosomatidae were inferred from mitochondrial ribosomal RNA gene sequences. Cladistic analysis of the DNA sequence data (779 bp; 162 informative characters) supported the monophyly of the sand lizards (Callisaurus, Cophosaurus, Holbrookia, and Uma), Petrosaurus, Phrynosoma, Urosaurus, and Uta. All the species of Sceloporus, except S. variabilis and S. chrysostictus, formed a clade. Except for a sand lizard + Phrynosoma clade, the intergeneric relationships inferred from the mtDNA were largely incongruent with recent cladistic analyses based on morphology. Sceloporus group monophyly was not supported, with Petrosaurus being a member of a clade containing Sator, Sceloporus, and Urosaurus, to the exclusion of Uta. The phylogenetic placement of Uta was ambiguous. The substitutional bias in the phrynosomatid mitochondrial rDNA sequences was examined, as well as the phylogenetic information content of transitions relative to transversions. There appeared to be a lower transition bias than observed in other vertebrate sequences, with some classes of transversions occurring as frequently as G <-> A transitions. Transitions were no less informative for phylogeny reconstruction than transversions. Therefore, transitions should not be down-weighted in phylogenetic analysis, as is often done.

  14. Mitochondrial DNA maintenance: an appraisal.

    PubMed

    Akhmedov, Alexander T; Marín-García, José

    2015-11-01

    Mitochondria play a crucial role in a variety of cellular processes ranging from energy metabolism, generation of reactive oxygen species (ROS), and Ca(2+) handling to stress responses, cell survival, and death. Malfunction of the organelle may contribute to the pathogenesis of neuromuscular disorders, cancer, premature aging, and cardiovascular diseases, including myocardial ischemia, cardiomyopathy, and heart failure. Mitochondria are unique as they contain their own genome organized into DNA-protein complexes, so-called mitochondrial nucleoids, along with multiprotein machineries, which promote mitochondrial DNA (mtDNA) replication, transcription, and repair. Although the organelle possesses almost all known nuclear DNA repair pathways, including base excision repair, mismatch repair, and recombinational repair, the proximity of mtDNA to the main sites of ROS production and the lack of protective histones may result in increased susceptibility to oxidative stress and other types of mtDNA damage. Defects in the components of these highly organized machineries, which mediate mtDNA maintenance (replication and repair), may result in accumulation of point mutations and/or deletions in mtDNA and decreased mtDNA copy number impairing mitochondrial function. This review will focus on the mechanisms of mtDNA maintenance with emphasis on the proteins implicated in these processes and their functional role in various disease conditions and aging.

  15. Implications of mitochondrial DNA mutations and mitochondrial dysfunction in tumorigenesis

    PubMed Central

    Lu, Jianxin; Sharma, Lokendra Kumar; Bai, Yidong

    2016-01-01

    Alterations in oxidative phosphorylation resulting from mitochondrial dysfunction have long been hypothesized to be involved in tumorigenesis. Mitochondria have recently been shown to play an important role in regulating both programmed cell death and cell proliferation. Furthermore, mitochondrial DNA (mtDNA) mutations have been found in various cancer cells. However, the role of these mtDNA mutations in tumorigenesis remains largely unknown. This review focuses on basic mitochondrial genetics, mtDNA mutations and consequential mitochondrial dysfunction associated with cancer. The potential molecular mechanisms, mediating the pathogenesis from mtDNA mutations and mitochondrial dysfunction to tumorigenesis are also discussed. PMID:19532122

  16. Mitochondrial DNA haplotypes induce differential patterns of DNA methylation that result in differential chromosomal gene expression patterns

    PubMed Central

    Lee, William T; Sun, Xin; Tsai, Te-Sha; Johnson, Jacqueline L; Gould, Jodee A; Garama, Daniel J; Gough, Daniel J; McKenzie, Matthew; Trounce, Ian A; St. John, Justin C

    2017-01-01

    Mitochondrial DNA copy number is strictly regulated during development as naive cells differentiate into mature cells to ensure that specific cell types have sufficient copies of mitochondrial DNA to perform their specialised functions. Mitochondrial DNA haplotypes are defined as specific regions of mitochondrial DNA that cluster with other mitochondrial sequences to show the phylogenetic origins of maternal lineages. Mitochondrial DNA haplotypes are associated with a range of phenotypes and disease. To understand how mitochondrial DNA haplotypes induce these characteristics, we used four embryonic stem cell lines that have the same set of chromosomes but possess different mitochondrial DNA haplotypes. We show that mitochondrial DNA haplotypes influence changes in chromosomal gene expression and affinity for nuclear-encoded mitochondrial DNA replication factors to modulate mitochondrial DNA copy number, two events that act synchronously during differentiation. Global DNA methylation analysis showed that each haplotype induces distinct DNA methylation patterns, which, when modulated by DNA demethylation agents, resulted in skewed gene expression patterns that highlight the effectiveness of the new DNA methylation patterns established by each haplotype. The haplotypes differentially regulate α-ketoglutarate, a metabolite from the TCA cycle that modulates the TET family of proteins, which catalyse the transition from 5-methylcytosine, indicative of DNA methylation, to 5-hydroxymethylcytosine, indicative of DNA demethylation. Our outcomes show that mitochondrial DNA haplotypes differentially modulate chromosomal gene expression patterns of naive and differentiating cells by establishing mitochondrial DNA haplotype-specific DNA methylation patterns. PMID:28900542

  17. Mitochondrial DNA and Cancer Epidemiology Workshop

    Cancer.gov

    A workshop to review the state-of-the science in the mitochondrial DNA field and its use in cancer epidemiology, and to develop a concept for a research initiative on mitochondrial DNA and cancer epidemiology.

  18. Markov chain for estimating human mitochondrial DNA mutation pattern

    NASA Astrophysics Data System (ADS)

    Vantika, Sandy; Pasaribu, Udjianna S.

    2015-12-01

    The Markov chain was proposed to estimate the human mitochondrial DNA mutation pattern. One DNA sequence was taken randomly from 100 sequences in Genbank. The nucleotide transition matrix and mutation transition matrix were estimated from this sequence. We determined whether the states (mutation/normal) are recurrent or transient. The results showed that both of them are recurrent.

  19. Mitochondrial DNA Damage and its Consequences for Mitochondrial Gene Expression

    PubMed Central

    Cline, Susan D.

    2012-01-01

    How mitochondria process DNA damage and whether a change in the steady-state level of mitochondrial DNA damage (mtDNA) contributes to mitochondrial dysfunction are questions that fuel burgeoning areas of research into aging and disease pathogenesis. Over the past decade, researchers have identified and measured various forms of endogenous and environmental mtDNA damage and have elucidated mtDNA repair pathways. Interestingly, mitochondria do not appear to contain the full range of DNA repair mechanisms that operate in the nucleus, although mtDNA contains types of damage that are targets of each nuclear DNA repair pathway. The reduced repair capacity may, in part, explain the high mutation frequency of the mitochondrial chromosome. Since mtDNA replication is dependent on transcription, mtDNA damage may alter mitochondrial gene expression at three levels: by causing DNA polymerase γ nucleotide incorporation errors leading to mutations, by interfering with the priming of mtDNA replication by the mitochondrial RNA polymerase, or by inducing transcriptional mutagenesis or premature transcript termination. This review summarizes our current knowledge of mtDNA damage, its repair, and its effects on mtDNA integrity and gene expression. PMID:22728831

  20. Mitochondrial DNA: A Blind Spot in Neuroepigenetics

    PubMed Central

    Manev, Hari; Dzitoyeva, Svetlana; Chen, Hu

    2012-01-01

    Neuroepigenetics, which includes nuclear DNA modifications such as 5-methylcytosine and 5-hydoxymethylcytosine and modifications of nuclear proteins such as histones, is emerging as the leading field in molecular neuroscience. Historically, a functional role for epigenetic mechanisms, including in neuroepigenetics, has been sought in the area of the regulation of nuclear transcription. However, one important compartment of mammalian cell DNA, different from nuclear but equally important for physiological and pathological processes (including in the brain), mitochondrial DNA has for the most part not had a systematic epigenetic characterization. The importance of mitochondria and mitochondrial DNA (particularly its mutations) in central nervous system physiology and pathology has long been recognized. Only recently have mechanisms of mitochondrial DNA methylation and hydroxymethylation, including the discovery of mitochondrial DNA-methyltransferases and the presence and the functionality of 5-methylcytosine and 5-hydroxymethylcytosine in mitochondrial DNA (e.g., in modifying the transcription of mitochondrial genome), been unequivocally recognized as a part of mammalian mitochondrial physiology. Here we summarize for the first time evidence supporting the existence of these mechanisms and we propose the term “mitochondrial epigenetics” to be used when referring to them. Currently, neuroepigenetics does not include mitochondrial epigenetics - a gap that we expect to close in the near future. PMID:22639700

  1. Primer removal during mammalian mitochondrial DNA replication.

    PubMed

    Uhler, Jay P; Falkenberg, Maria

    2015-10-01

    The small circular mitochondrial genome in mammalian cells is replicated by a dedicated replisome, defects in which can cause mitochondrial disease in humans. A fundamental step in mitochondrial DNA (mtDNA) replication and maintenance is the removal of the RNA primers needed for replication initiation. The nucleases RNase H1, FEN1, DNA2, and MGME1 have been implicated in this process. Here we review the role of these nucleases in the light of primer removal pathways in mitochondria, highlight associations with disease, as well as consider the implications for mtDNA replication initiation. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

  2. Experimental strategies towards treating mitochondrial DNA disorders.

    PubMed

    Gardner, Julie L; Craven, Lyndsey; Turnbull, Douglass M; Taylor, Robert W

    2007-06-01

    An extensive range of molecular defects have been identified in the human mitochondrial genome (mtDNA), causing a range of clinical phenotypes characterized by mitochondrial respiratory chain dysfunction. Sadly, given the complexities of mitochondrial genetics, there are no available cures for mtDNA disorders. In this review, we consider experimental, genetic-based strategies that have been or are being explored towards developing treatments, focussing on two specific areas which we are actively pursuing--assessing the benefit of exercise training for patients with mtDNA defects, and the prevention of mtDNA disease transmission.

  3. Transcription and replication of mitochondrial DNA.

    PubMed

    Clayton, D A

    2000-07-01

    The physical isolation of mammalian mitochondrial DNA (mtDNA) over 30 years ago marked the beginning of studies of its structure, replication and the expression of its genetic content. Such analyses have revealed a number of surprises: novel DNA structural features of the circular genome such as the displacement loop (D-loop); multiple sized and deleted forms of the circular genome; a minimal set of mitochondrially encoded rRNAs and tRNAs needed for translation; a bacteriophage-like, nuclear-encoded mitochondrial RNA polymerase for transcription; and a direct linkage between transcription and the commitment to replication of the leading mtDNA strand that centres on the nuclear encoded mitochondrial transcription factor A. One of the more recent revelations is the existence, near the D-loop, of an atypical, stable RNA-DNA hybrid (or R-loop) at the origin of mammalian leading-strand DNA replication, composed of the parent DNA strands and an RNA transcript. In mammalian mitochondrial systems, all of the proteins known to be involved in DNA replication are encoded in the nucleus. Thus alterations and deficiencies in mtDNA replication must arise from mutations in mtDNA regulatory sequences and nuclear gene defects. Further studies of the relationships between nuclear-encoded proteins and their mtDNA target sequences could result in strategies to manipulate genotypes within cellular mtDNA populations.

  4. Mitochondrial DNA with a large-scale deletion causes two distinct mitochondrial disease phenotypes in mice.

    PubMed

    Katada, Shun; Mito, Takayuki; Ogasawara, Emi; Hayashi, Jun-Ichi; Nakada, Kazuto

    2013-09-04

    Studies in patients have suggested that the clinical phenotypes of some mitochondrial diseases might transit from one disease to another (e.g., Pearson syndrome [PS] to Kearns-Sayre syndrome) in single individuals carrying mitochondrial (mt) DNA with a common deletion (ΔmtDNA), but there is no direct experimental evidence for this. To determine whether ΔmtDNA has the pathologic potential to induce multiple mitochondrial disease phenotypes, we used trans-mitochondrial mice with a heteroplasmic state of wild-type mtDNA and ΔmtDNA (mito-miceΔ). Late-stage embryos carrying ≥50% ΔmtDNA showed abnormal hematopoiesis and iron metabolism in livers that were partly similar to PS (PS-like phenotypes), although they did not express sideroblastic anemia that is a typical symptom of PS. More than half of the neonates with PS-like phenotypes died by 1 month after birth, whereas the rest showed a decrease of ΔmtDNA load in the affected tissues, peripheral blood and liver, and they recovered from PS-like phenotypes. The proportion of ΔmtDNA in various tissues of the surviving mito-miceΔ increased with time, and Kearns-Sayre syndrome-like phenotypes were expressed when the proportion of mtDNA in various tissues reached >70-80%. Our model mouse study clearly showed that a single ΔmtDNA was responsible for at least two distinct disease phenotypes at different ages and suggested that the level and dynamics of mtDNA load in affected tissues would be important for the onset and transition of mitochondrial disease phenotypes in mice.

  5. Mitochondrial DNA with a Large-Scale Deletion Causes Two Distinct Mitochondrial Disease Phenotypes in Mice

    PubMed Central

    Katada, Shun; Mito, Takayuki; Ogasawara, Emi; Hayashi, Jun-Ichi; Nakada, Kazuto

    2013-01-01

    Studies in patients have suggested that the clinical phenotypes of some mitochondrial diseases might transit from one disease to another (e.g., Pearson syndrome [PS] to Kearns-Sayre syndrome) in single individuals carrying mitochondrial (mt) DNA with a common deletion (∆mtDNA), but there is no direct experimental evidence for this. To determine whether ∆mtDNA has the pathologic potential to induce multiple mitochondrial disease phenotypes, we used trans-mitochondrial mice with a heteroplasmic state of wild-type mtDNA and ∆mtDNA (mito-mice∆). Late-stage embryos carrying ≥50% ∆mtDNA showed abnormal hematopoiesis and iron metabolism in livers that were partly similar to PS (PS-like phenotypes), although they did not express sideroblastic anemia that is a typical symptom of PS. More than half of the neonates with PS-like phenotypes died by 1 month after birth, whereas the rest showed a decrease of ∆mtDNA load in the affected tissues, peripheral blood and liver, and they recovered from PS-like phenotypes. The proportion of ∆mtDNA in various tissues of the surviving mito-mice∆ increased with time, and Kearns-Sayre syndrome−like phenotypes were expressed when the proportion of ∆mtDNA in various tissues reached >70–80%. Our model mouse study clearly showed that a single ∆mtDNA was responsible for at least two distinct disease phenotypes at different ages and suggested that the level and dynamics of ∆mtDNA load in affected tissues would be important for the onset and transition of mitochondrial disease phenotypes in mice. PMID:23853091

  6. Mitochondrial DNA, restoring Beethovens music.

    PubMed

    Merheb, Maxime; Vaiedelich, Stéphane; Maniguet, Thiérry; Hänni, Catherine

    2016-01-01

    Great ancient composers have endured many obstacles and constraints which are very difficult to understand unless we perform the restoration process of ancient music. Species identification in leather used during manufacturing is the key step to start such a restoration process in order to produce a facsimile of a museum piano. Our study reveals the species identification in the leather covering the hammer head in a piano created by Erard in 1802. This is the last existing piano similar to the piano that Beethoven used with its leather preserved in its original state. The leather sample was not present in a homogeneous piece, yet combined with glue. Using a DNA extraction method that avoids PCR inhibitors; we discovered that sheep and cattle are the origin of the combination. To identify the species in the leather, we focused on the amounts of mitochondrial DNA in both leather and glue and results have led us to the conclusion that the leather used to cover the hammer head in this piano was made of cattle hide.

  7. Cryptic crested newt diversity at the Eurasian transition: the mitochondrial DNA phylogeography of Near Eastern Triturus newts.

    PubMed

    Wielstra, B; Themudo, G Espregueira; Güçlü, O; Olgun, K; Poyarkov, N A; Arntzen, J W

    2010-09-01

    Crested newts of the Triturus karelinii group occur in a phylogeographically understudied region: the Near East. Controversy surrounds the systematic position of these newts within the complete crested newt assemblage (the Triturus cristatus superspecies). We explore the situation using mitochondrial sequence data (ND2 and ND4, approximately 1.7kb) and employing different methods of phylogenetic inference (Bayesian inference and Maximum Likelihood using mixed models) and molecular dating (r8s and BEAST). The T. karelinii group is monophyletic and constitutes one of four main lineages in the T. cristatus superspecies. The separation of the T. karelinii group from the remaining crested newts around 9Ma is related to the formation of the Mid-Aegean Trench, which separated the Balkan and Anatolian landmasses. The T. karelinii group comprises three geographically structured clades (eastern, central and western). The genetic divergence shown by these clades is comparable to that among recognized crested newt species. We suggest the uplift of the Armenian Plateau to be responsible for the separation of the eastern clade around 7Ma, and the re-establishment of a marine connection between the Black Sea and the Mediterranean at the end of the Messinian Salinity Crisis to have caused the split between the central and western clade around 5.5Ma. Genetic structuring within the three clades dates to the Quaternary Ice Age (<2.59Ma) and is associated with alternating periods of isolation and reconnection caused by periodic changes in sea level and surface runoff.

  8. Mitochondrial DNA heterogeneity in Tunisian Berbers.

    PubMed

    Fadhlaoui-Zid, K; Plaza, S; Calafell, F; Ben Amor, M; Comas, D; Bennamar El gaaied, A

    2004-05-01

    Berbers live in groups scattered across North Africa whose origins and genetic relationships with their neighbours are not well established. The first hypervariable segment of the mitochondrial DNA (mtDNA) control region was sequenced in a total of 155 individuals from three Tunisian Berber groups and compared to other North Africans. The mtDNA lineages found belong to a common set of mtDNA haplogroups already described in North Africa. Besides the autochthonous North African U6 haplogroup, a group of L3 lineages characterized by the transition at position 16041 seems to be restricted to North Africans, suggesting that an expansion of this group of lineages took place around 10500 years ago in North Africa, and spread to neighbouring populations. Principal components and the coordinate analyses show that some Berber groups (the Tuareg, the Mozabite, and the Chenini-Douiret) are outliers within the North African genetic landscape. This outlier position is consistent with an isolation process followed by genetic drift in haplotype frequencies, and with the high heterogeneity displayed by Berbers compared to Arab samples as shown in the AMOVA. Despite this Berber heterogeneity, no significant differences were found between Berber and Arab samples, suggesting that the Arabization was mainly a cultural process rather than a demographic replacement.

  9. Melatonin protects against common deletion of mitochondrial DNA-augmented mitochondrial oxidative stress and apoptosis.

    PubMed

    Jou, Mei-Jie; Peng, Tsung-I; Yu, Pai-Zu; Jou, Shuo-Bin; Reiter, Russel J; Chen, Jin-Yi; Wu, Hong-Yueh; Chen, Chih-Chun; Hsu, Lee-Fen

    2007-11-01

    Defected mitochondrial respiratory chain (RC), in addition to causing a severe ATP deficiency, often augments reactive oxygen species (ROS) generation in mitochondria (mROS) which enhances pathological conditions and diseases. Previously, we demonstrated a potent endogenously RC defect-augmented mROS associated dose-dependently with a commonly seen large-scale deletion of 4977 base pairs of mitochondrial DNA (mtDNA), i.e. the common deletion (CD). As current treatments for CD-associated diseases are rather supplementary and ineffective, we investigated whether melatonin, a potential mitochondrial protector, provides beneficial protection for CD-augmented mitochondrial oxidative stress and apoptosis particularly upon the induction of a secondary oxidative stress. Detailed mechanistic investigations were performed by using laser scanning dual fluorescence imaging microscopy to provide precise spatial and temporal resolution of mitochondrial events at single cell level. We demonstrate, for the first time, that melatonin significantly prevents CD-augmented mROS formation under basal conditions as well as at early time-points upon secondary oxidative stress induced by H2O2 exposure. Thus, melatonin prevents mROS-mediated depolarization of mitochondrial membrane potential (DeltaPsim) and subsequent opening of the mitochondrial permeability transition pore (MPTP) and cytochrome c release. Moreover, melatonin prevents depletion of cardiolipin which appears to be crucial for postponing later MPTP opening, disruption of the mitochondrial membrane and apoptosis. Finally, the protection provided by melatonin is superior to those caused by the suppression of mitochondrial Ca2+ regulators including the mitochondrial Na+-Ca2) exchanger, the MPTP, and the mitochondrial Ca2+ uniporter and by antioxidants including vitamin E and mitochondria-targeted coenzyme Q, MitoQ. As RC defect-augmented endogenous mitochondrial oxidative stress is centrally involved in a variety of pathological

  10. (Somatic mutations in nuclear and mitochondrial DNA)

    SciTech Connect

    Not Available

    1992-01-01

    The study is concerned the design of new assays that may detect rare somatic mutations in nuclear and mitochondrial DNA, which may increase upon exposure to mutagens, and thus become a marker of human exposure to such mutagens. Two assays for somatic mutation were presented, one for mitochondrial DNA deletions which was developed by the author, and one for deletions of the ADA gene which resides in the nucleus.

  11. Large mitochondrial DNA deletion in an infant with addison disease.

    PubMed

    Duran, Gloria P; Martinez-Aguayo, A; Poggi, H; Lagos, M; Gutierrez, D; Harris, P R

    2012-01-01

    Mitochondrial diseases are a group of disorders caused by mutations in nuclear DNA or mitochondrial DNA, usually involving multiple organ systems. Primary adrenal insufficiency due to mitochondrial disease is extremely infrequent and has been reported in association with mitochondrial DNA deletion syndromes such as Kearns-Sayre syndrome. To report a 3-year-old boy with Addison disease, congenital glaucoma, chronic pancreatitis, and mitochondrial myopathy due to large mitochondrial DNA deletion. Molecular analysis of mitochondrial DNA samples obtained from peripheral blood, oral mucosa, and muscle tissue. A novel large mitochondrial DNA deletion of 7,372bp was identified involving almost all genes on the big arch of mtDNA. This case reaffirms the association of adrenal insufficiency and mitochondrial DNA deletions and presents new evidence that glaucoma is another manifestation of mitochondrial diseases. Due to the genetic and clinical heterogeneity of mitochondrial disorders, molecular analysis is crucial to confirm diagnosis and to allow accurate genetic counseling.

  12. Borrowing Nuclear DNA Helicases to Protect Mitochondrial DNA

    PubMed Central

    Ding, Lin; Liu, Yilun

    2015-01-01

    In normal cells, mitochondria are the primary organelles that generate energy, which is critical for cellular metabolism. Mitochondrial dysfunction, caused by mitochondrial DNA (mtDNA) mutations or an abnormal mtDNA copy number, is linked to a range of human diseases, including Alzheimer’s disease, premature aging‎ and cancer. mtDNA resides in the mitochondrial lumen, and its duplication requires the mtDNA replicative helicase, Twinkle. In addition to Twinkle, many DNA helicases, which are encoded by the nuclear genome and are crucial for nuclear genome integrity, are transported into the mitochondrion to also function in mtDNA replication and repair. To date, these helicases include RecQ-like helicase 4 (RECQ4), petite integration frequency 1 (PIF1), DNA replication helicase/nuclease 2 (DNA2) and suppressor of var1 3-like protein 1 (SUV3). Although the nuclear functions of some of these DNA helicases have been extensively studied, the regulation of their mitochondrial transport and the mechanisms by which they contribute to mtDNA synthesis and maintenance remain largely unknown. In this review, we attempt to summarize recent research progress on the role of mammalian DNA helicases in mitochondrial genome maintenance and the effects on mitochondria-associated diseases. PMID:25984607

  13. Borrowing nuclear DNA helicases to protect mitochondrial DNA.

    PubMed

    Ding, Lin; Liu, Yilun

    2015-05-13

    In normal cells, mitochondria are the primary organelles that generate energy, which is critical for cellular metabolism. Mitochondrial dysfunction, caused by mitochondrial DNA (mtDNA) mutations or an abnormal mtDNA copy number, is linked to a range of human diseases, including Alzheimer's disease, premature aging‎ and cancer. mtDNA resides in the mitochondrial lumen, and its duplication requires the mtDNA replicative helicase, Twinkle. In addition to Twinkle, many DNA helicases, which are encoded by the nuclear genome and are crucial for nuclear genome integrity, are transported into the mitochondrion to also function in mtDNA replication and repair. To date, these helicases include RecQ-like helicase 4 (RECQ4), petite integration frequency 1 (PIF1), DNA replication helicase/nuclease 2 (DNA2) and suppressor of var1 3-like protein 1 (SUV3). Although the nuclear functions of some of these DNA helicases have been extensively studied, the regulation of their mitochondrial transport and the mechanisms by which they contribute to mtDNA synthesis and maintenance remain largely unknown. In this review, we attempt to summarize recent research progress on the role of mammalian DNA helicases in mitochondrial genome maintenance and the effects on mitochondria-associated diseases.

  14. Mitochondrial DNA triplication and punctual mutations in patients with mitochondrial neuromuscular disorders

    SciTech Connect

    Mkaouar-Rebai, Emna; Felhi, Rahma; Tabebi, Mouna; Alila-Fersi, Olfa; Chamkha, Imen; Maalej, Marwa; Ammar, Marwa; Kammoun, Fatma; Keskes, Leila; Hachicha, Mongia; Fakhfakh, Faiza

    2016-04-29

    Mitochondrial diseases are a heterogeneous group of disorders caused by the impairment of the mitochondrial oxidative phosphorylation system which have been associated with various mutations of the mitochondrial DNA (mtDNA) and nuclear gene mutations. The clinical phenotypes are very diverse and the spectrum is still expanding. As brain and muscle are highly dependent on OXPHOS, consequently, neurological disorders and myopathy are common features of mtDNA mutations. Mutations in mtDNA can be classified into three categories: large-scale rearrangements, point mutations in tRNA or rRNA genes and point mutations in protein coding genes. In the present report, we screened mitochondrial genes of complex I, III, IV and V in 2 patients with mitochondrial neuromuscular disorders. The results showed the presence the pathogenic heteroplasmic m.9157G>A variation (A211T) in the MT-ATP6 gene in the first patient. We also reported the first case of triplication of 9 bp in the mitochondrial NC7 region in Africa and Tunisia, in association with the novel m.14924T>C in the MT-CYB gene in the second patient with mitochondrial neuromuscular disorder. - Highlights: • We reported 2 patients with mitochondrial neuromuscular disorders. • The heteroplasmic MT-ATP6 9157G>A variation was reported. • A triplication of 9 bp in the mitochondrial NC7 region was detected. • The m.14924T>C transition (S60P) in the MT-CYB gene was found.

  15. Role and Treatment of Mitochondrial DNA-Related Mitochondrial Dysfunction in Sporadic Neurodegenerative Diseases

    PubMed Central

    Swerdlow, Russell H.

    2012-01-01

    Several sporadic neurodegenerative diseases display phenomena that directly or indirectly relate to mitochondrial function. Data suggesting altered mitochondrial function in these diseases could arise from mitochondrial DNA (mtDNA) are reviewed. Approaches for manipulating mitochondrial function and minimizing the downstream consequences of mitochondrial dysfunction are discussed. PMID:21902672

  16. Improving upon nature's somatic mitochondrial DNA therapies.

    PubMed

    Dani, M A; Dani, S U

    2010-06-01

    Mitochondrial DNA (mtDNA) directs key metabolic functions in eukaryotic cells. While a number of mtDNA mutations are known causes of human diseases and age-related dysfunctions, some mtDNA haplotypes are associated with extreme longevity. Despite the mutagenic mitochondrial environment naturally enhancing somatic mtDNA mutation rates, mtDNA remains grossly stable along generations of plant and animal species including man. This relative stability can be accounted for by the purging of deleterious mutations by natural selection operating on growing cells, tissues, organisms and populations, as observed in gametogenesis, embryogenesis, oncogenesis and cladogenesis. In the adult multicellular organism, however, mtDNA mutations accumulate in slowly dividing cells, and, to a much higher degree, in postmitotic cells and tissues. Dynamic mitochondrial fusion and fission, by redistributing polymorphic mtDNA molecules; mitophagy, by clearing defective mitochondria and mutated mtDNA; compensatory mutations and mtDNA repair can compensate for the accumulation of mtDNA mutations only to a certain extent, thereby creating a dysfunctional threshold. Here we hypothesize that this threshold is naturally up-regulated by both vertical and horizontal transfers of mtDNA from stem cells or cell types which retain the capacity of purging deleterious mtDNA through cell division and natural selection in the adult organism. When these natural cell and tissue mtDNA reserves are exhausted, artificial mtDNA therapy may provide for additional threshold up-regulation. Replacement of mtDNA has been already successfully accomplished in early stage embryos and stem cells in a number of species including primates. It is thus simply a matter of refinement of technique that somatic mtDNA therapy, i.e., therapy of pathological conditions based on the transfer of mtDNA to somatic eukaryotic cells and tissues, becomes a medical reality.

  17. Mitochondrial replacement in human oocytes carrying pathogenic mitochondrial DNA mutations.

    PubMed

    Kang, Eunju; Wu, Jun; Gutierrez, Nuria Marti; Koski, Amy; Tippner-Hedges, Rebecca; Agaronyan, Karen; Platero-Luengo, Aida; Martinez-Redondo, Paloma; Ma, Hong; Lee, Yeonmi; Hayama, Tomonari; Van Dyken, Crystal; Wang, Xinjian; Luo, Shiyu; Ahmed, Riffat; Li, Ying; Ji, Dongmei; Kayali, Refik; Cinnioglu, Cengiz; Olson, Susan; Jensen, Jeffrey; Battaglia, David; Lee, David; Wu, Diana; Huang, Taosheng; Wolf, Don P; Temiakov, Dmitry; Belmonte, Juan Carlos Izpisua; Amato, Paula; Mitalipov, Shoukhrat

    2016-12-08

    Maternally inherited mitochondrial (mt)DNA mutations can cause fatal or severely debilitating syndromes in children, with disease severity dependent on the specific gene mutation and the ratio of mutant to wild-type mtDNA (heteroplasmy) in each cell and tissue. Pathogenic mtDNA mutations are relatively common, with an estimated 778 affected children born each year in the United States. Mitochondrial replacement therapies or techniques (MRT) circumventing mother-to-child mtDNA disease transmission involve replacement of oocyte maternal mtDNA. Here we report MRT outcomes in several families with common mtDNA syndromes. The mother's oocytes were of normal quality and mutation levels correlated with those in existing children. Efficient replacement of oocyte mutant mtDNA was performed by spindle transfer, resulting in embryos containing >99% donor mtDNA. Donor mtDNA was stably maintained in embryonic stem cells (ES cells) derived from most embryos. However, some ES cell lines demonstrated gradual loss of donor mtDNA and reversal to the maternal haplotype. In evaluating donor-to-maternal mtDNA interactions, it seems that compatibility relates to mtDNA replication efficiency rather than to mismatch or oxidative phosphorylation dysfunction. We identify a polymorphism within the conserved sequence box II region of the D-loop as a plausible cause of preferential replication of specific mtDNA haplotypes. In addition, some haplotypes confer proliferative and growth advantages to cells. Hence, we propose a matching paradigm for selecting compatible donor mtDNA for MRT.

  18. Enhanced tumorigenicity by mitochondrial DNA mild mutations.

    PubMed

    Cruz-Bermúdez, Alberto; Vallejo, Carmen G; Vicente-Blanco, Ramiro J; Gallardo, María Esther; Fernández-Moreno, Miguel Ángel; Quintanilla, Miguel; Garesse, Rafael

    2015-05-30

    To understand how mitochondria are involved in malignant transformation we have generated a collection of transmitochondrial cybrid cell lines on the same nuclear background (143B) but with mutant mitochondrial DNA (mtDNA) variants with different degrees of pathogenicity. These include the severe mutation in the tRNALys gene, m.8363G>A, and the three milder yet prevalent Leber's hereditary optic neuropathy (LHON) mutations in the MT-ND1 (m.3460G>A), MT-ND4 (m.11778G>A) and MT-ND6 (m.14484T>C) mitochondrial genes. We found that 143B ρ0 cells devoid of mtDNA and cybrids harboring wild type mtDNA or that causing severe mitochondrial dysfunction do not produce tumors when injected in nude mice. By contrast cybrids containing mild mutant mtDNAs exhibit different tumorigenic capacities, depending on OXPHOS dysfunction.The differences in tumorigenicity correlate with an enhanced resistance to apoptosis and high levels of NOX expression. However, the final capacity of the different cybrid cell lines to generate tumors is most likely a consequence of a complex array of pro-oncogenic and anti-oncogenic factors associated with mitochondrial dysfunction.Our results demonstrate the essential role of mtDNA in tumorigenesis and explain the numerous and varied mtDNA mutations found in human tumors, most of which give rise to mild mitochondrial dysfunction.

  19. Enhanced tumorigenicity by mitochondrial DNA mild mutations

    PubMed Central

    Cruz-Bermúdez, Alberto; Vallejo, Carmen G.; Vicente-Blanco, Ramiro J.; Gallardo, María Esther; Fernández-Moreno, Miguel Ángel; Quintanilla, Miguel; Garesse, Rafael

    2015-01-01

    To understand how mitochondria are involved in malignant transformation we have generated a collection of transmitochondrial cybrid cell lines on the same nuclear background (143B) but with mutant mitochondrial DNA (mtDNA) variants with different degrees of pathogenicity. These include the severe mutation in the tRNALys gene, m.8363G>A, and the three milder yet prevalent Leber's hereditary optic neuropathy (LHON) mutations in the MT-ND1 (m.3460G>A), MT-ND4 (m.11778G>A) and MT-ND6 (m.14484T>C) mitochondrial genes. We found that 143B ρ0 cells devoid of mtDNA and cybrids harboring wild type mtDNA or that causing severe mitochondrial dysfunction do not produce tumors when injected in nude mice. By contrast cybrids containing mild mutant mtDNAs exhibit different tumorigenic capacities, depending on OXPHOS dysfunction. The differences in tumorigenicity correlate with an enhanced resistance to apoptosis and high levels of NOX expression. However, the final capacity of the different cybrid cell lines to generate tumors is most likely a consequence of a complex array of pro-oncogenic and anti-oncogenic factors associated with mitochondrial dysfunction. Our results demonstrate the essential role of mtDNA in tumorigenesis and explain the numerous and varied mtDNA mutations found in human tumors, most of which give rise to mild mitochondrial dysfunction. PMID:25909222

  20. [Saturation of the Polish mitochondrial DNA database].

    PubMed

    Daca, Patrycja; Mielnik-Sikorska, Marta; Bednarek, Jarosław; Grzybowski, Tomasz

    2010-01-01

    The main objective of the study was a statistical evaluation of Polish mitochondrial DNA database, consisting of 1253 maternally unrelated individuals from seven different regions of Poland. Four relevant parameters were examined: haplotype diversity, nucleotide diversity, number of polymorphic positions and number of haplotypes, including HVS I and HVS II mtDNA regions. The results show that while haplotype and nucleotide diversities have already reached saturation level, the number of haplotypes and polymorphic positions rises continuously inside the database. These results indicate a need for a substantial increase in the number of haplotypes in Polish mitochondrial DNA database.

  1. Prevalence of rare mitochondrial DNA mutations in mitochondrial disorders

    PubMed Central

    Bannwarth, Sylvie; Procaccio, Vincent; Lebre, Anne Sophie; Jardel, Claude; Chaussenot, Annabelle; Hoarau, Claire; Maoulida, Hassani; Charrier, Nathanaël; Gai, Xiaowu; Xie, Hongbo M; Ferre, Marc; Fragaki, Konstantina; Hardy, Gaëlle; Mousson de Camaret, Bénédicte; Marlin, Sandrine; Dhaenens, Claire Marie; Slama, Abdelhamid; Rocher, Christophe; Paul Bonnefont, Jean; Rötig, Agnès; Aoutil, Nadia; Gilleron, Mylène; Desquiret-Dumas, Valérie; Reynier, Pascal; Ceresuela, Jennifer; Jonard, Laurence; Devos, Aurore; Espil-Taris, Caroline; Martinez, Delphine; Gaignard, Pauline; Le Quan Sang, Kim-Hanh; Amati-Bonneau, Patrizia; Falk, Marni J; Florentz, Catherine; Chabrol, Brigitte; Durand-Zaleski, Isabelle; Paquis-Flucklinger, Véronique

    2013-01-01

    Abstract Background Mitochondrial DNA (mtDNA) diseases are rare disorders whose prevalence is estimated around 1 in 5000. Patients are usually tested only for deletions and for common mutations of mtDNA which account for 5–40% of cases, depending on the study. However, the prevalence of rare mtDNA mutations is not known. Methods We analysed the whole mtDNA in a cohort of 743 patients suspected of manifesting a mitochondrial disease, after excluding deletions and common mutations. Both heteroplasmic and homoplasmic variants were identified using two complementary strategies (Surveyor and MitoChip). Multiple correspondence analyses followed by hierarchical ascendant cluster process were used to explore relationships between clinical spectrum, age at onset and localisation of mutations. Results 7.4% of deleterious mutations and 22.4% of novel putative mutations were identified. Pathogenic heteroplasmic mutations were more frequent than homoplasmic mutations (4.6% vs 2.8%). Patients carrying deleterious mutations showed symptoms before 16 years of age in 67% of cases. Early onset disease (<1 year) was significantly associated with mutations in protein coding genes (mainly in complex I) while late onset disorders (>16 years) were associated with mutations in tRNA genes. MTND5 and MTND6 genes were identified as ‘hotspots’ of mutations, with Leigh syndrome accounting for the large majority of associated phenotypes. Conclusions Rare mitochondrial DNA mutations probably account for more than 7.4% of patients with respiratory chain deficiency. This study shows that a comprehensive analysis of mtDNA is essential, and should include young children, for an accurate diagnosis that is now accessible with the development of next generation sequencing technology. PMID:23847141

  2. Ancient Out-of-Africa Mitochondrial DNA Variants Associate with Distinct Mitochondrial Gene Expression Patterns

    PubMed Central

    Mishmar, Dan

    2016-01-01

    Mitochondrial DNA (mtDNA) variants have been traditionally used as markers to trace ancient population migrations. Although experiments relying on model organisms and cytoplasmic hybrids, as well as disease association studies, have served to underline the functionality of certain mtDNA SNPs, only little is known of the regulatory impact of ancient mtDNA variants, especially in terms of gene expression. By analyzing RNA-seq data of 454 lymphoblast cell lines from the 1000 Genomes Project, we found that mtDNA variants defining the most common African genetic background, the L haplogroup, exhibit a distinct overall mtDNA gene expression pattern, which was independent of mtDNA copy numbers. Secondly, intra-population analysis revealed subtle, yet significant, expression differences in four tRNA genes. Strikingly, the more prominent African mtDNA gene expression pattern best correlated with the expression of nuclear DNA-encoded RNA-binding proteins, and with SNPs within the mitochondrial RNA-binding proteins PTCD1 and MRPS7. Our results thus support the concept of an ancient regulatory transition of mtDNA-encoded genes as humans left Africa to populate the rest of the world. PMID:27812116

  3. Inferring ethnicity from mitochondrial DNA sequence

    PubMed Central

    2011-01-01

    Background The assignment of DNA samples to coarse population groups can be a useful but difficult task. One such example is the inference of coarse ethnic groupings for forensic applications. Ethnicity plays an important role in forensic investigation and can be inferred with the help of genetic markers. Being maternally inherited, of high copy number, and robust persistence in degraded samples, mitochondrial DNA may be useful for inferring coarse ethnicity. In this study, we compare the performance of methods for inferring ethnicity from the sequence of the hypervariable region of the mitochondrial genome. Results We present the results of comprehensive experiments conducted on datasets extracted from the mtDNA population database, showing that ethnicity inference based on support vector machines (SVM) achieves an overall accuracy of 80-90%, consistently outperforming nearest neighbor and discriminant analysis methods previously proposed in the literature. We also evaluate methods of handling missing data and characterize the most informative segments of the hypervariable region of the mitochondrial genome. Conclusions Support vector machines can be used to infer coarse ethnicity from a small region of mitochondrial DNA sequence with surprisingly high accuracy. In the presence of missing data, utilizing only the regions common to the training sequences and a test sequence proves to be the best strategy. Given these results, SVM algorithms are likely to also be useful in other DNA sequence classification applications. PMID:21554759

  4. Characterization of mitochondrial DNA in primary cardiomyopathies.

    PubMed

    Bobba, A; Giannattasio, S; Pucci, A; Lippolis, R; Camaschella, C; Marra, E

    1995-12-29

    With the aim of studying the involvement of the mitochondrial genome in the impairment of heart function, mitochondrial DNA was analyzed by modified primer shift-polymerase chain reaction in a panel of young patients affected by primary cardiomyopathies. Mitochondrial DNA molecules harboring the 7436 bp deletion were specifically found in cardiomyopathic patients as compared with a panel of control subjects. The 4977 bp deletion was commonly detected among the subjects analyzed whereas none of the specific tRNA gene point mutations generally associated with the cardiomyopathic trait were detected. The presence of the 7436 bp deletion as a consequence of a premature aging of the heart muscle, secondary to heart dysfunction, is discussed.

  5. Mitochondrial DNA diagnosis for taeniasis and cysticercosis.

    PubMed

    Yamasaki, Hiroshi; Nakao, Minoru; Sako, Yasuhito; Nakaya, Kazuhiro; Sato, Marcello Otake; Ito, Akira

    2006-01-01

    Molecular diagnosis for taeniasis and cysticercosis in humans on the basis of mitochondrial DNA analysis was reviewed. Development and application of three different methods, including restriction fragment length polymorphism analysis, base excision sequence scanning thymine-base analysis and multiplex PCR, were described. Moreover, molecular diagnosis of cysticerci found in specimens submitted for histopathology and the molecular detection of taeniasis using copro-DNA were discussed.

  6. Mitochondrial chaperone DnaJA3 induces Drp1-dependent mitochondrial fragmentation.

    PubMed

    Elwi, Adam N; Lee, Byoungchun; Meijndert, H Christopher; Braun, Janice E A; Kim, Sung-Woo

    2012-08-01

    Mitochondrial morphology is dynamic and controlled by coordinated fusion and fission pathways. The role of mitochondrial chaperones in mitochondrial morphological changes and pathology is currently unclear. Here we report that altered levels of DnaJA3 (Tid1/mtHsp40) a mitochondrial member of the DnaJ protein family, and heat shock protein (Hsp) co-chaperone of matrix 70 kDa Hsp70 (mtHsp70/mortalin/HSPA9), induces mitochondrial fragmentation. Suppression of DnaJA3 induced mitochondrial fragmentation in HeLa cells. Elevated levels of DnaJA3 in normal Hs68 fibroblast cells and HeLa, SKN-SH, U87 and U251 cancer cell lines induces mitochondrial fragmentation. Mitochondrial fragmentation induction was not observed in HeLa cells when other DnaJA family members, or mitochondrial DnaJ protein HSC20, were ectopically expressed, indicating that the effects on mitochondrial morphology were specific to DnaJA3. We show that the DnaJ domain (amino acids 88-168) of DnaJA3 is sufficient for the induction of mitochondrial fragmentation. Furthermore, an H121Q point mutation of the DnaJ domain, which abrogates interaction and activation of mtHsp70 ATPase, eliminates fragmentation induced by DnaJA3. This suggests that DnaJA3 interaction with mtHsp70 may be critical in mitochondrial morphological changes. DnaJA3-induced mitochondrial fragmentation was dependent on fission factor dynamin-related protein 1 (Drp1). Ectopic expression of the mitofusins (Mfn1 and Mfn2), however, does not rescue DnaJA3-induced mitochondrial fragmentation. Lastly, elevated levels of DnaJA3 inducing mitochondrial fragmentation were associated with reduction in cell viability. Taken together, elevated DnaJA3 induces Drp1-depedendent mitochondrial fragmentation and decreased cell viability.

  7. Mitochondrial DNA hypomethylation in chrome plating workers.

    PubMed

    Yang, Linqing; Xia, Bo; Yang, Xueqin; Ding, Hong; Wu, Desheng; Zhang, Huimin; Jiang, Gaofeng; Liu, Jianjun; Zhuang, Zhixiong

    2016-01-22

    A matched case-control study was conducted to examine the relationship between chromium (Cr) exposure and variation in mitochondrial (mt) DNA methylation. We enrolled 29 pairs of subjects in this study; Cr exposure was confirmed in the cases by detecting blood Cr and other metal ion concentrations. DNA damage caused by Cr exposure was determined in terms of binucleated micronucleus frequency (BNMN) and mtDNA copy number. Finally, a Sequenom MassARRAY platform was applied to inspect the DNA methylation levels of mitochondrially encoded tRNA phenylalanine (MT-TF), mitochondrially encoded 12S RNA (MT-RNR1), and long interspersed nucleotide element-1 (LINE-1) genes. The blood Cr ion concentration and micronucleus frequency of the Cr-exposed group were higher than those of the control group, whereas the mtDNA copy number remained unchanged. The methylation levels of MT-TF and MT-RNR1 but not LINE-1 were significantly lower in Cr-exposed workers. Pearson correlation analysis showed that workers with higher blood Cr ion concentrations exhibited lower MT-TF and MT-RNR1 gene methylation, and multiple linear regression analysis indicated that CpG sites 1 and 2 in MT-TF and CpG site 6 in MT-RNR1 were affected. These results suggested that methylation level of mtDNA has the possibility of acting as an alternative effect biomarker for Cr exposure. Copyright © 2015. Published by Elsevier Ireland Ltd.

  8. [Hepatomioneuropathy secondary to mitochondrial DNA depletion].

    PubMed

    Blanco-Barca, M O; Gómez-Lado, C; Campos-González, Y; Castro-Gago, M

    2007-04-01

    Mitochondrial DNA depletion (mtDNA) is an highly heterogeneous condition characterized by a decreased number of mtDNA copies. The patient is a 22-month-old girl with generalized hypotonia, marked weakness, respiratory failure, arterial hypertension, hyperlactacidemia, hepatosplenomegaly and mild hypertransaminasemia without hepatic failure neither hypoketotic hypoglycemia. Electromyographic findings were consistent with neuromyopathy and muscle biopsy suggested a neurogenic atrophy. Electron microscopy revealed lipid droplets, subsarcolemmal accumulation of mitochondrias and glycogen granules. Respiratory chain enzime activities were normal. Genetic study in muscle showed mtDNA depletion, and the diagnosis of spinal muscular atrophy caused by survival motoneuron gene deletion was excluded. This case might be a novel phenotype of mtDNA depletion which could be named hepatomioneuropatyc form. A normal result of respiratory chain enzimes in muscle doesn't excluded mtDNA depletion.

  9. Restoration of normal embryogenesis by mitochondrial supplementation in pig oocytes exhibiting mitochondrial DNA deficiency

    PubMed Central

    Cagnone, Gael L. M.; Tsai, Te-Sha; Makanji, Yogeshwar; Matthews, Pamela; Gould, Jodee; Bonkowski, Michael S.; Elgass, Kirstin D.; Wong, Ashley S. A.; Wu, Lindsay E.; McKenzie, Matthew; Sinclair, David A.; John, Justin C. St.

    2016-01-01

    An increasing number of women fail to achieve pregnancy due to either failed fertilization or embryo arrest during preimplantation development. This often results from decreased oocyte quality. Indeed, reduced mitochondrial DNA copy number (mitochondrial DNA deficiency) may disrupt oocyte quality in some women. To overcome mitochondrial DNA deficiency, whilst maintaining genetic identity, we supplemented pig oocytes selected for mitochondrial DNA deficiency, reduced cytoplasmic maturation and lower developmental competence, with autologous populations of mitochondrial isolate at fertilization. Supplementation increased development to blastocyst, the final stage of preimplantation development, and promoted mitochondrial DNA replication prior to embryonic genome activation in mitochondrial DNA deficient oocytes but not in oocytes with normal levels of mitochondrial DNA. Blastocysts exhibited transcriptome profiles more closely resembling those of blastocysts from developmentally competent oocytes. Furthermore, mitochondrial supplementation reduced gene expression patterns associated with metabolic disorders that were identified in blastocysts from mitochondrial DNA deficient oocytes. These results demonstrate the importance of the oocyte’s mitochondrial DNA investment in fertilization outcome and subsequent embryo development to mitochondrial DNA deficient oocytes. PMID:26987907

  10. Variable phenotypes in a family with mitochondrial encephalomyopathy harboring a 3291T > C mutation in mitochondrial DNA.

    PubMed

    Sunami, Yoko; Sugaya, Keizo; Chihara, Norio; Goto, Yu-ichi; Matsubara, Shiro

    2011-10-01

    We present a Japanese family suffering from mitochondrial encephalomyopathy associated with a T-to-C transition at mitochondrial DNA (mtDNA) nucleotide position 3291. Clinical manifestations of the patients include cerebellar ataxia with myopathy, recurrent headache, and myoclonus and epilepsy. The phenotypic variation among the affected members of a single family and the mutational analysis showing maternal inheritance in a heteroplasmic fashion are consistent with well-recognized phenomena associated with many pathogenic point mutations of mtDNA tRNA genes. The 3291 mutation is a rare mtDNA mutation whose clinical presentation had only been reported in three sporadic cases. This is the first report of a family segregating the 3291 mutation with multigenerational matrilinear recurrence of mitochondrial encephalopathy. Our findings provide conclusive evidence for the pathogenicity of the 3291T > C mutation in mtDNA and its characteristic clinical heterogeneity.

  11. PCR-based analysis of mitochondrial DNA copy number, mitochondrial DNA damage, and nuclear DNA damage

    PubMed Central

    Gonzalez-Hunt, Claudia P.; Rooney, John P.; Ryde, Ian T.; Anbalagan, Charumathi; Joglekar, Rashmi

    2016-01-01

    Because of the role DNA damage and depletion play in human disease, it is important to develop and improve tools to assess these endpoints. This unit describes PCR-based methods to measure nuclear and mitochondrial DNA damage and copy number. Long amplicon quantitative polymerase chain reaction (LA-QPCR) is used to detect DNA damage by measuring the number of polymerase-inhibiting lesions present based on the amount of PCR amplification; real-time PCR (RT-PCR) is used to calculate genome content. In this unit we provide step-by-step instructions to perform these assays in Homo sapiens, Mus musculus, Rattus norvegicus, Caenorhabditis elegans, Drosophila melanogaster, Danio rerio, Oryzias latipes, Fundulus grandis, and Fundulus heteroclitus, and discuss the advantages and disadvantages of these assays. PMID:26828332

  12. Mitochondrial permeability transition pore and calcium handling.

    PubMed

    Wong, Renee; Steenbergen, Charles; Murphy, Elizabeth

    2012-01-01

    Opening of a large conductance channel in the inner mitochondrial membrane, known as the mitochondrial permeability transition (MPT) pore, has been shown to be a primary mediator of cell death in the heart subjected to ischemia-reperfusion injury. Inhibitors of the MPT have been shown to reduce cardiac ischemia-reperfusion injury. Furthermore, most cardioprotective strategies appear to reduce ischemic cell death either by reducing the triggers for the opening of the MPT, such as reducing calcium overload or reactive oxygen species, or by more direct inhibition of the MPT. This chapter focuses on key issues in the study of the MPT and provides some methods for measuring MPT opening in isolated mitochondria.

  13. Mitochondrial DNA disease: new options for prevention.

    PubMed

    Craven, Lyndsey; Elson, Joanna L; Irving, Laura; Tuppen, Helen A; Lister, Lisa M; Greggains, Gareth D; Byerley, Samantha; Murdoch, Alison P; Herbert, Mary; Turnbull, Doug

    2011-10-15

    Very recently, two papers have presented intriguing data suggesting that prevention of transmission of human mitochondrial DNA (mtDNA) disease is possible. [Craven, L., Tuppen, H.A., Greggains, G.D., Harbottle, S.J., Murphy, J.L., Cree, L.M., Murdoch, A.P., Chinnery, P.F., Taylor, R.W., Lightowlers, R.N. et al. (2010) Pronuclear transfer in human embryos to prevent transmission of mitochondrial DNA disease. Nature, 465, 82-85. Tachibana, M., Sparman, M., Sritanaudomchai, H., Ma, H., Clepper, L., Woodward, J., Li, Y., Ramsey, C., Kolotushkina, O. and Mitalipov, S. (2009) Mitochondrial gene replacement in primate offspring and embryonic stem cells. Nature, 461, 367-372.] These recent advances raise hopes for families with mtDNA disease; however, the successful translational of these techniques to clinical practice will require further research to test for safety and to maximize efficacy. Furthermore, in the UK, amendment to the current legislation will be required. Here, we discuss the clinical and scientific background, studies we believe are important to establish safety and efficacy of the techniques and some of the potential concerns about the use of these approaches.

  14. The inheritance of pathogenic mitochondrial DNA mutations.

    PubMed

    Cree, L M; Samuels, D C; Chinnery, P F

    2009-12-01

    Mitochondrial DNA mutations cause disease in >1 in 5000 of the population, and approximately 1 in 200 of the population are asymptomatic carriers of a pathogenic mtDNA mutation. Many patients with these pathogenic mtDNA mutations present with a progressive, disabling neurological syndrome that leads to major disability and premature death. There is currently no effective treatment for mitochondrial disorders, placing great emphasis on preventing the transmission of these diseases. An empiric approach can be used to guide genetic counseling for common mtDNA mutations, but many families transmit rare or unique molecular defects. There is therefore a pressing need to develop techniques to prevent transmission based on a solid understanding of the biological mechanisms. Several recent studies have cast new light on the genetics and cell biology of mtDNA inheritance, but these studies have also raised new controversies. Here we compare and contrast these findings and discuss their relevance for the transmission of human mtDNA diseases.

  15. Mitochondrial DNA haplotype predicts deafness risk

    SciTech Connect

    Hutchin, T.; Cortopassi, G.

    1995-12-18

    Since mitochondrial DNA (mtDNA) does not recombine in humans, once deleterious variation arises within a particular mtDNA clone it remains linked to that clonal type. An A to G mutation at mtDNA position 1555 confers matrilineal deafness among Asians and others. Two major mtDNA types (I and II) have been defined in Asians by D-loop sequencing. We have determined the D-loop sequence of 8 unrelated deaf Asians bearing the 1555G mutation, and find that 7 are of type II, whereas only one is of type I. Thus the frequency of the 1555G mutation is higher in type II mtDNA than type I (P = 0.035, binomial test), and persons with type II mtDNA are more likely to become deaf. Type II mtDNAs are rare in the Caucasian population, which may explain the rarity of this form of deafness in the United States. Negative Darwinian selection is expected to rapidly eliminate mtDNAs bearing severely deleterious mutations; but mildly deleterious mutations whose phenotype is expressed after reproduction should persist on the mtDNA background in which they arose. Thus determination of mtDNA clonal type has the potential to predict human risk for diseases that are the result of mildly deleterious mtDNA mutations which confer a post-reproductive phenotype. 4 refs., 1 fig.

  16. Mutation hot spots in mammalian mitochondrial DNA.

    PubMed

    Galtier, Nicolas; Enard, David; Radondy, Yoan; Bazin, Eric; Belkhir, Khalid

    2006-02-01

    Animal mitochondrial DNA is characterized by a remarkably high level of within-species homoplasy, that is, phylogenetic incongruence between sites of the molecule. Several investigators have invoked recombination to explain it, challenging the dogma of maternal, clonal mitochondrial inheritance in animals. Alternatively, a high level of homoplasy could be explained by the existence of mutation hot spots. By using an exhaustive mammalian data set, we test the hot spot hypothesis by comparing patterns of site-specific polymorphism and divergence in several groups of closely related species, including hominids. We detect significant co-occurrence of synonymous polymorphisms among closely related species in various mammalian groups, and a correlation between the site-specific levels of variability within humans (on one hand) and between Hominoidea species (on the other hand), indicating that mutation hot spots actually exist in mammalian mitochondrial coding regions. The whole data, however, cannot be explained by a simple mutation hot spots model. Rather, we show that the site-specific mutation rate quickly varies in time, so that the same sites are not hypermutable in distinct lineages. This study provides a plausible mutation model that potentially accounts for the peculiar distribution of mitochondrial sequence variation in mammals without the need for invoking recombination. It also gives hints about the proximal causes of mitochondrial site-specific hypermutability in humans.

  17. Complete Mitochondrial DNA Diversity in Iranians

    PubMed Central

    Derenko, Miroslava; Malyarchuk, Boris; Bahmanimehr, Ardeshir; Denisova, Galina; Perkova, Maria; Farjadian, Shirin; Yepiskoposyan, Levon

    2013-01-01

    Due to its pivotal geographical location and proximity to transcontinental migratory routes, Iran has played a key role in subsequent migrations, both prehistoric and historic, between Africa, Asia and Europe. To shed light on the genetic structure of the Iranian population as well as on the expansion patterns and population movements which affected this region, the complete mitochondrial genomes of 352 Iranians were obtained. All Iranian populations studied here exhibit similarly high diversity values comparable to the other groups from the Caucasus, Anatolia and Europe. The results of AMOVA and MDS analyses did not associate any regional and/or linguistic group of populations in the Anatolia/Caucasus and Iran region pointing to close genetic positions of Persians and Qashqais to each other and to Armenians, and Azeris from Iran to Georgians. By reconstructing the complete mtDNA phylogeny of haplogroups R2, N3, U1, U3, U5a1g, U7, H13, HV2, HV12, M5a and C5c we have found a previously unexplored genetic connection between the studied Iranian populations and the Arabian Peninsula, India, Near East and Europe, likely the result of both ancient and recent gene flow. Our results for Persians and Qashqais point to a continuous increase of the population sizes from ∼24 kya to the present, although the phase between 14-24 kya is thought to be hyperarid according to the Gulf Oasis model. Since this would have affected hunter-gatherer ranges and mobility patterns and forced them to increasingly rely on coastal resources, this transition can explain the human expansion across the Persian Gulf region. PMID:24244704

  18. Mitochondrial DNA polymorphism in a maternal lineage of Holstein cows.

    PubMed Central

    Hauswirth, W W; Laipis, P J

    1982-01-01

    Two mitochondrial genotypes are shown to exist within one Holstein cow maternal lineage. They were detected by the appearance of an extra Hae III recognition site in one genotype. The nucleotide sequence of this region has been determined and the genotypes are distinguished by an adenine/guanine base transition which creates the new Hae III site. This point mutation occurs within an open reading frame at the third position of a glycine codon and therefore does not alter the amino acid sequence. The present pattern of genotypes within the lineage demands that multiple shifts between genotypes must have occurred within the past 20 years with the most rapid shift taking place in no more than 4 years and indicates that mitochondrial DNA polymorphism can occur between maternally related mammals. The process that gave rise to different genotypes in one lineage is clearly of fundamental importance in understanding intraspecific mitochondrial polymorphism and evolution in mammals. Several potential mechanisms for rapid mitochondrial DNA variation are discussed in light of these results. Images PMID:6289312

  19. Sequencing mitochondrial DNA polymorphisms by hybridization

    SciTech Connect

    Chee, M.S.; Lockhart, D.J.; Hubbell, E.

    1994-09-01

    We have investigated the use of DNA chips for genetic analysis, using human mitochondrial DNA (mtDNA) as a model. The DNA chips are made up of ordered arrays of DNA oligonucleotide probes, synthesized on a glass substrate using photolithographic techniques. The synthesis site for each different probe is specifically addressed by illumination of the substrate through a photolithographic mask, achieving selective deprotection Nucleoside phosphoramidites bearing photolabile protecting groups are coupled only to exposed sites. Repeated cycles of deprotection and coupling generate all the probes in parallel. The set of 4{sup N} N-mer probes can be synthesized in only 4N steps. Any subset can be synthesized in 4N steps. Any subset can be synthesized in 4N or fewer steps. Sequences amplified from the D-loop region of human mitochondrial DNA (mtDNA) were fluorescently labelled and hybridized to DNA chips containing probes specific for mtDNA. Each nucleotide of a 1.3 kb region spanning the D loop is represented by four probes on the chip. Each probe has a different base at the position of interest: together they comprise a set of A, C, G and T probes which are otherwise identical. In principle, only one probe-target hybrid will be a perfect match. The other three will be single base mismatches. Fluorescence imaging of the hybridized chip allows quantification of hybridization signals. Heterozygous mixtures of sequences can also be characterized. We have developed software to quantitate and interpret the hybridization signals, and to call the sequence automatically. Results of sequence analysis of human mtDNAs will be presented.

  20. Mitochondrial DNA analysis in Parkinson's disease.

    PubMed

    Schapira, A H; Holt, I J; Sweeney, M; Harding, A E; Jenner, P; Marsden, C D

    1990-01-01

    The reduced form of nicotinamide adenine dinucleotide coenzyme Q reductase (complex I) activity has recently been shown to be deficient in the substantia nigra of patients dying with Parkinson's disease. This biochemical defect is identical to that produced by the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), which also produces parkinsonism in humans. Complex I comprises 25 polypeptides, seven of which are encoded by mitochondrial DNA. Restriction fragment analysis of substantia nigra DNA from six patients with Parkinson's disease did not show any major deletion. In two cases, there were different novel polymorphisms that were not observed in control brain (n = 6) or blood (n = 34) samples.

  1. What is the mitochondrial permeability transition pore?

    PubMed

    Halestrap, Andrew P

    2009-06-01

    Under conditions of mitochondrial calcium overload, especially when accompanied by oxidative stress, elevated phosphate concentrations and adenine nucleotide depletion, a non-specific pore, the mitochondrial permeability transition pore (MPTP), opens in the inner mitochondrial membrane. MPTP opening enables free passage into the mitochondria of molecules of <1.5 kDa including protons. The resulting uncoupling of oxidative phosphorylation leads to ATP depletion and necrotic cell death and it is now widely recognised that MPTP opening is a major cause of reperfusion injury and an effective target for cardioprotection. The properties of the MPTP are well defined, but despite extensive research in many laboratories, its exact molecular identity remains uncertain. Knockout studies have confirmed a role for cyclophilin-D (CyP-D), probably mediated by its peptidyl-prolyl cis-trans isomerase activity facilitating a conformational change of an inner membrane protein. However, the identity of the membrane component(s) remains controversial. Knockout studies have eliminated an essential role for either the voltage dependent anion channel (VDAC) or the adenine nucleotide translocase (ANT), although a regulatory role for the ANT was confirmed. Our own studies implicate the mitochondrial phosphate carrier (PiC) in MPTP formation and are consistent with a calcium-triggered conformational change of the PiC, facilitated by CyP-D, inducing pore opening. We propose that this is enhanced by an association of the PiC with the "c" conformation of the ANT. Agents that modulate pore opening may act on either or both the PiC and the ANT. However, knockdown and reconstitution studies are awaited to confirm or refute this model.

  2. Higher plant mitochondrial DNA: Genomes, genes, mutants, transcription, translation

    SciTech Connect

    Not Available

    1986-01-01

    This volume contains brief summaries of 63 presentations given at the International Workshop on Higher Plant Mitochondrial DNA. The presentations are organized into topical discussions addressing plant genomes, mitochondrial genes, cytoplasmic male sterility, transcription, translation, plasmids and tissue culture. (DT)

  3. Number matters: control of mammalian mitochondrial DNA copy number.

    PubMed

    Clay Montier, Laura L; Deng, Janice J; Bai, Yidong

    2009-03-01

    Regulation of mitochondrial biogenesis is essential for proper cellular functioning. Mitochondrial DNA (mtDNA) depletion and the resulting mitochondrial malfunction have been implicated in cancer, neurodegeneration, diabetes, aging, and many other human diseases. Although it is known that the dynamics of the mammalian mitochondrial genome are not linked with that of the nuclear genome, very little is known about the mechanism of mtDNA propagation. Nevertheless, our understanding of the mode of mtDNA replication has advanced in recent years, though not without some controversies. This review summarizes our current knowledge of mtDNA copy number control in mammalian cells, while focusing on both mtDNA replication and turnover. Although mtDNA copy number is seemingly in excess, we reason that mtDNA copy number control is an important aspect of mitochondrial genetics and biogenesis and is essential for normal cellular function.

  4. The mitochondrial permeability transition and taurine.

    PubMed

    Palmi, M; Youmbi, G T; Sgaragli, G; Meini, A; Benocci, A; Fusi, F; Frosini, M; Della Corte, L; Davey, G; Tipton, K F

    2000-01-01

    Perturbed cellular calcium homeostasis has been implicated in both apoptosis and necrosis, but the role of altered mitochondrial calcium handling in the cell death process is unclear. Recently we found that taurine, a naturally occurring amino acid potentiates Ca2+ sequestration by rat liver mitochondria. These data, which accounted for the taurine antagonism on Ca2+ release induced by the neurotoxins 1-methyl-4-phenylpyridinium plus 6-hydroxy dopamine previously reported, prompted us to investigate the effects of taurine on the permeability transition (PT) induced experimentally by high Ca2+ plus phosphate concentrations. The parameters used to measure the PT were, mitochondrial swelling, cytochrome c release and membrane potential changes. The results showed that, whereas taurine failed to reverse changes of these parameters, cyclosporin A completely reversed them. Even though these results exclude a role in PT regulation under such gross insult conditions, they cannot exclude an important role for taurine in controlling pore-opening under milder more physiological PT-inducing conditions.

  5. The mitochondrial permeability transition in neurologic disease.

    PubMed

    Norenberg, M D; Rao, K V Rama

    2007-06-01

    Mitochondria, being the principal source of cellular energy, are vital for cell life. Yet, ironically, they are also major mediators of cell death, either by necrosis or apoptosis. One means by which these adverse effects occur is through the mitochondrial permeability transition (mPT) whereby the inner mitochondrial membrane suddenly becomes excessively permeable to ions and other solutes, resulting in a collapse of the inner membrane potential, ultimately leading to energy failure and cell necrosis. The mPT may also bring about the release of various factors known to cause apoptotic cell death. The principal factors leading to the mPT are elevated levels of intracellular Ca2+ and oxidative stress. Characteristically, the mPT is inhibited by cyclosporin A. This article will briefly discuss the concept of the mPT, its molecular composition, its inducers and regulators, agents that influence its activity and describe the consequences of its induction. Lastly, we will review its potential contribution to acute neurological disorders, including ischemia, trauma, and toxic-metabolic conditions, as well as its role in chronic neurodegenerative conditions such as Alzheimer's disease, Parkinson's disease, Huntington's disease and amyotrophic lateral sclerosis.

  6. Mitochondrial quality control: Cell-type-dependent responses to pathological mutant mitochondrial DNA

    PubMed Central

    Malena, Adriana; Pantic, Boris; Borgia, Doriana; Sgarbi, Gianluca; Solaini, Giancarlo; Holt, Ian J.; Spinazzola, Antonella; Perissinotto, Egle; Sandri, Marco; Baracca, Alessandra; Vergani, Lodovica

    2016-01-01

    ABSTRACT Pathological mutations in the mitochondrial DNA (mtDNA) produce a diverse range of tissue-specific diseases and the proportion of mutant mitochondrial DNA can increase or decrease with time via segregation, dependent on the cell or tissue type. Previously we found that adenocarcinoma (A549.B2) cells favored wild-type (WT) mtDNA, whereas rhabdomyosarcoma (RD.Myo) cells favored mutant (m3243G) mtDNA. Mitochondrial quality control (mtQC) can purge the cells of dysfunctional mitochondria via mitochondrial dynamics and mitophagy and appears to offer the perfect solution to the human diseases caused by mutant mtDNA. In A549.B2 and RD.Myo cybrids, with various mutant mtDNA levels, mtQC was explored together with macroautophagy/autophagy and bioenergetic profile. The 2 types of tumor-derived cell lines differed in bioenergetic profile and mitophagy, but not in autophagy. A549.B2 cybrids displayed upregulation of mitophagy, increased mtDNA removal, mitochondrial fragmentation and mitochondrial depolarization on incubation with oligomycin, parameters that correlated with mutant load. Conversely, heteroplasmic RD.Myo lines had lower mitophagic markers that negatively correlated with mutant load, combined with a fully polarized and highly fused mitochondrial network. These findings indicate that pathological mutant mitochondrial DNA can modulate mitochondrial dynamics and mitophagy in a cell-type dependent manner and thereby offer an explanation for the persistence and accumulation of deleterious variants. PMID:27627835

  7. Mitochondrial DNA content, an inaccurate biomarker of mitochondrial alteration in human immunodeficiency virus-related lipodystrophy.

    PubMed

    Kim, Min Ji; Jardel, Claude; Barthélémy, Cyrille; Jan, Véronique; Bastard, Jean Philippe; Fillaut-Chapin, Sandrine; Houry, Sydney; Capeau, Jacqueline; Lombès, Anne

    2008-05-01

    Lipoatrophy is a prevalent side effect of antiretroviral treatment of human immunodeficiency virus (HIV) infection. Its mechanisms are still disputed but include mitochondrial toxicity and, in particular, mitochondrial DNA (mtDNA) depletion induced by nucleoside reverse transcriptase inhibitors. To obtain an integrated evaluation of the mitochondrial alteration in lipoatrophy, we investigated the DNA, RNA, and protein levels in 15 samples of abdominal subcutaneous adipose tissue from HIV-infected patients with peripheral lipoatrophy and compared the results with those for 15 samples from age- and body mass index-matched controls. The DNA and RNA analyses used PCR-based techniques, while proteins were quantified with enzyme-linked immunosorbent assay and measurement of activities with spectrophotometric assays. Depletion of mtDNA and mtDNA-encoded MT-CO2 mRNA was present, but normal levels of mtDNA-dependent activity (cytochrome c oxidase) and protein (MT-CO2p) showed that it was compensated for. An increase in nuclear-DNA-dependent mitochondrial activities (citrate synthase and malate dehydrogenase) and protein (COX4I1p), as well as transcriptional up-regulation of nuclear-DNA-encoded mitochondrial genes (COX4I1 and UCP2), demonstrated increased mitochondrial biogenesis. However, the expression of the known transcription factors of mitochondrial biogenesis (TFAM, NRF1, GABPA, PPARGC1A, PPARGC1B, and PPRC1) was normal or decreased. Increased amounts of activated caspase 3 and of DDIT3 mRNA showed the induction of apoptosis and oxidative stress, respectively. The mtDNA content did not correlate with any other mitochondrial parameter. In conclusion, mtDNA content does not appear to be an accurate biomarker of mitochondrial alteration in lipoatrophic adipose tissue. The preservation of mtDNA-dependent mitochondrial functions occurred despite severe mtDNA depletion. The presence of significant oxidative stress and apoptosis did not correlate with the mtDNA content.

  8. Mitochondrial DNA Content, an Inaccurate Biomarker of Mitochondrial Alteration in Human Immunodeficiency Virus-Related Lipodystrophy▿

    PubMed Central

    Kim, Min Ji; Jardel, Claude; Barthélémy, Cyrille; Jan, Véronique; Bastard, Jean Philippe; Fillaut-Chapin, Sandrine; Houry, Sydney; Capeau, Jacqueline; Lombès, Anne

    2008-01-01

    Lipoatrophy is a prevalent side effect of antiretroviral treatment of human immunodeficiency virus (HIV) infection. Its mechanisms are still disputed but include mitochondrial toxicity and, in particular, mitochondrial DNA (mtDNA) depletion induced by nucleoside reverse transcriptase inhibitors. To obtain an integrated evaluation of the mitochondrial alteration in lipoatrophy, we investigated the DNA, RNA, and protein levels in 15 samples of abdominal subcutaneous adipose tissue from HIV-infected patients with peripheral lipoatrophy and compared the results with those for 15 samples from age- and body mass index-matched controls. The DNA and RNA analyses used PCR-based techniques, while proteins were quantified with enzyme-linked immunosorbent assay and measurement of activities with spectrophotometric assays. Depletion of mtDNA and mtDNA-encoded MT-CO2 mRNA was present, but normal levels of mtDNA-dependent activity (cytochrome c oxidase) and protein (MT-CO2p) showed that it was compensated for. An increase in nuclear-DNA-dependent mitochondrial activities (citrate synthase and malate dehydrogenase) and protein (COX4I1p), as well as transcriptional up-regulation of nuclear-DNA-encoded mitochondrial genes (COX4I1 and UCP2), demonstrated increased mitochondrial biogenesis. However, the expression of the known transcription factors of mitochondrial biogenesis (TFAM, NRF1, GABPA, PPARGC1A, PPARGC1B, and PPRC1) was normal or decreased. Increased amounts of activated caspase 3 and of DDIT3 mRNA showed the induction of apoptosis and oxidative stress, respectively. The mtDNA content did not correlate with any other mitochondrial parameter. In conclusion, mtDNA content does not appear to be an accurate biomarker of mitochondrial alteration in lipoatrophic adipose tissue. The preservation of mtDNA-dependent mitochondrial functions occurred despite severe mtDNA depletion. The presence of significant oxidative stress and apoptosis did not correlate with the mtDNA content. PMID

  9. Mitochondrial calcium uniporter regulator 1 (MCUR1) regulates the calcium threshold for the mitochondrial permeability transition

    PubMed Central

    Artiga, Daniel J.; Abiria, Sunday A.; Clapham, David E.

    2016-01-01

    During the mitochondrial permeability transition, a large channel in the inner mitochondrial membrane opens, leading to the loss of multiple mitochondrial solutes and cell death. Key triggers include excessive reactive oxygen species and mitochondrial calcium overload, factors implicated in neuronal and cardiac pathophysiology. Examining the differential behavior of mitochondrial Ca2+ overload in Drosophila versus human cells allowed us to identify a gene, MCUR1, which, when expressed in Drosophila cells, conferred permeability transition sensitive to electrophoretic Ca2+ uptake. Conversely, inhibiting MCUR1 in mammalian cells increased the Ca2+ threshold for inducing permeability transition. The effect was specific to the permeability transition induced by Ca2+, and such resistance to overload translated into improved cell survival. Thus, MCUR1 expression regulates the Ca2+ threshold required for permeability transition. PMID:26976564

  10. Mitochondrial calcium uniporter regulator 1 (MCUR1) regulates the calcium threshold for the mitochondrial permeability transition.

    PubMed

    Chaudhuri, Dipayan; Artiga, Daniel J; Abiria, Sunday A; Clapham, David E

    2016-03-29

    During the mitochondrial permeability transition, a large channel in the inner mitochondrial membrane opens, leading to the loss of multiple mitochondrial solutes and cell death. Key triggers include excessive reactive oxygen species and mitochondrial calcium overload, factors implicated in neuronal and cardiac pathophysiology. Examining the differential behavior of mitochondrial Ca(2+) overload in Drosophila versus human cells allowed us to identify a gene, MCUR1, which, when expressed in Drosophila cells, conferred permeability transition sensitive to electrophoretic Ca(2+) uptake. Conversely, inhibiting MCUR1 in mammalian cells increased the Ca(2+) threshold for inducing permeability transition. The effect was specific to the permeability transition induced by Ca(2+), and such resistance to overload translated into improved cell survival. Thus, MCUR1 expression regulates the Ca(2+) threshold required for permeability transition.

  11. Characterization of Nucleotide Misincorporation Patterns in the Iceman's Mitochondrial DNA

    PubMed Central

    Olivieri, Cristina; Ermini, Luca; Rizzi, Ermanno; Corti, Giorgio; Bonnal, Raoul; Luciani, Stefania; Marota, Isolina; De Bellis, Gianluca; Rollo, Franco

    2010-01-01

    Background The degradation of DNA represents one of the main issues in the genetic analysis of archeological specimens. In the recent years, a particular kind of post-mortem DNA modification giving rise to nucleotide misincorporation (“miscoding lesions”) has been the object of extensive investigations. Methodology/Principal Findings To improve our knowledge regarding the nature and incidence of ancient DNA nucleotide misincorporations, we have utilized 6,859 (629,975 bp) mitochondrial (mt) DNA sequences obtained from the 5,350–5,100-years-old, freeze-desiccated human mummy popularly known as the Tyrolean Iceman or Ötzi. To generate the sequences, we have applied a mixed PCR/pyrosequencing procedure allowing one to obtain a particularly high sequence coverage. As a control, we have produced further 8,982 (805,155 bp) mtDNA sequences from a contemporary specimen using the same system and starting from the same template copy number of the ancient sample. From the analysis of the nucleotide misincorporation rate in ancient, modern, and putative contaminant sequences, we observed that the rate of misincorporation is significantly lower in modern and putative contaminant sequence datasets than in ancient sequences. In contrast, type 2 transitions represent the vast majority (85%) of the observed nucleotide misincorporations in ancient sequences. Conclusions/Significance This study provides a further contribution to the knowledge of nucleotide misincorporation patterns in DNA sequences obtained from freeze-preserved archeological specimens. In the Iceman system, ancient sequences can be clearly distinguished from contaminants on the basis of nucleotide misincorporation rates. This observation confirms a previous identification of the ancient mummy sequences made on a purely phylogenetical basis. The present investigation provides further indication that the majority of ancient DNA damage is reflected by type 2 (cytosine→thymine/guanine→adenine) transitions and

  12. Role of the mitochondrial DNA replication machinery in mitochondrial DNA mutagenesis, aging and age-related diseases.

    PubMed

    DeBalsi, Karen L; Hoff, Kirsten E; Copeland, William C

    2017-01-01

    As regulators of bioenergetics in the cell and the primary source of endogenous reactive oxygen species (ROS), dysfunctional mitochondria have been implicated for decades in the process of aging and age-related diseases. Mitochondrial DNA (mtDNA) is replicated and repaired by nuclear-encoded mtDNA polymerase γ (Pol γ) and several other associated proteins, which compose the mtDNA replication machinery. Here, we review evidence that errors caused by this replication machinery and failure to repair these mtDNA errors results in mtDNA mutations. Clonal expansion of mtDNA mutations results in mitochondrial dysfunction, such as decreased electron transport chain (ETC) enzyme activity and impaired cellular respiration. We address the literature that mitochondrial dysfunction, in conjunction with altered mitochondrial dynamics, is a major driving force behind aging and age-related diseases. Additionally, interventions to improve mitochondrial function and attenuate the symptoms of aging are examined. Published by Elsevier B.V.

  13. Mitochondrial DNA variation among Anopheles albimanus populations.

    PubMed

    De Merida, A M; Palmieri, M; Yurrita, M; Molina, A; Molina, E; Black, W C

    1999-08-01

    Barriers to gene flow between Pacific and Atlantic coast populations of Anopheles albimanus were reported in an earlier study of variation in the intergenic spacer of the nuclear ribosomal DNA. We examined the distribution of mitochondrial DNA haplotypes among A. albimanus populations to test for gene flow barriers with an independent genetic marker. A region of the NADH dehydrogenase subunit 5 gene was amplified by the polymerase chain reaction (PCR) in 1,105 mosquitoes collected from 16 locations in Guatemala and in single collections from Mexico, Honduras, Nicaragua, Costa Rica, Panama, Colombia, and Venezuela. The PCR products were tested for variation using single strand conformation polymorphism analysis and 45 haplotypes were detected. Haplotype frequencies did not vary between coasts in Guatemala. Populations within approximately 200 km of one another were panmictic. However, at distances > 200 km, FST and geographic distances were correlated suggesting that populations are isolated by distance.

  14. Acceptance of Domestic Cat Mitochondrial DNA in a Criminal Proceeding

    PubMed Central

    Lyons, Leslie A.; Grahn, Robert A.; Kun, Teri J.; Netzel, Linda R.; Wictum, Elizabeth E.; Halverson, Joy L.

    2014-01-01

    Shed hair from domestic animals readily adheres to clothing and other contact items, providing a source of transfer evidence for criminal investigations. Mitochondrial DNA is often the only option for DNA analysis of shed hair. Human mitochondrial DNA analysis has been accepted in the US court system since 1996. The murder trial of the State of Missouri versus Henry L. Polk, Jr. represents the first legal proceeding where cat mitochondrial DNA analysis was introduced into evidence. The mitochondrial DNA evidence was initially considered inadmissible due to concerns about the cat dataset and the scientific acceptance of the marker. Those concerns were subsequently addressed, and the evidence was deemed admissible. This report reviews the case in regards to the cat biological evidence and its ultimate admission as generally accepted and reliable. Expansion and saturation analysis of the cat mitochondrial DNA control region dataset supported the initial interpretation of the evidence. PMID:25086413

  15. Irc3 is a mitochondrial DNA branch migration enzyme

    PubMed Central

    Gaidutšik, Ilja; Sedman, Tiina; Sillamaa, Sirelin; Sedman, Juhan

    2016-01-01

    Integrity of mitochondrial DNA (mtDNA) is essential for cellular energy metabolism. In the budding yeast Saccharomyces cerevisiae, a large number of nuclear genes influence the stability of mitochondrial genome; however, most corresponding gene products act indirectly and the actual molecular mechanisms of mtDNA inheritance remain poorly characterized. Recently, we found that a Superfamily II helicase Irc3 is required for the maintenance of mitochondrial genome integrity. Here we show that Irc3 is a mitochondrial DNA branch migration enzyme. Irc3 modulates mtDNA metabolic intermediates by preferential binding and unwinding Holliday junctions and replication fork structures. Furthermore, we demonstrate that the loss of Irc3 can be complemented with mitochondrially targeted RecG of Escherichia coli. We suggest that Irc3 could support the stability of mtDNA by stimulating fork regression and branch migration or by inhibiting the formation of irregular branched molecules. PMID:27194389

  16. Acceptance of domestic cat mitochondrial DNA in a criminal proceeding.

    PubMed

    Lyons, Leslie A; Grahn, Robert A; Kun, Teri J; Netzel, Linda R; Wictum, Elizabeth E; Halverson, Joy L

    2014-11-01

    Shed hair from domestic animals readily adheres to clothing and other contact items, providing a source of transfer evidence for criminal investigations. Mitochondrial DNA is often the only option for DNA analysis of shed hair. Human mitochondrial DNA analysis has been accepted in the US court system since 1996. The murder trial of the State of Missouri versus Henry L. Polk, Jr. represents the first legal proceeding where cat mitochondrial DNA analysis was introduced into evidence. The mitochondrial DNA evidence was initially considered inadmissible due to concerns about the cat dataset and the scientific acceptance of the marker. Those concerns were subsequently addressed, and the evidence was deemed admissible. This report reviews the case in regards to the cat biological evidence and its ultimate admission as generally accepted and reliable. Expansion and saturation analysis of the cat mitochondrial DNA control region dataset supported the initial interpretation of the evidence.

  17. Urinary mitochondrial DNA is a biomarker of mitochondrial disruption and renal dysfunction in acute kidney injury

    PubMed Central

    Whitaker, Ryan M.; Stallons, L. Jay; Kneff, Joshua E.; Alge, Joseph L.; Harmon, Jennifer L.; Rahn, Jennifer J.; Arthur, John M.; Beeson, Craig C.; Chan, Sherine L.; Schnellmann, Rick G.

    2015-01-01

    Recent studies show the importance of mitochondrial dysfunction in the initiation and progression of acute kidney injury (AKI). However, no biomarkers exist linking renal injury to mitochondrial function and integrity. To this end, we evaluated urinary mitochondrial DNA (UmtDNA) as a biomarker of renal injury and function in humans with AKI following cardiac surgery. mtDNA was isolated from the urine of patients following cardiac surgery and quantified by qPCR. Patients were stratified into no AKI, stable AKI and progressive AKI groups based on Acute Kidney Injury Network (AKIN) staging. UmtDNA was elevated in progressive AKI patients, and was associated with progression of patients with AKI at collection to higher AKIN stages. To evaluate the relationship of UmtDNA to measures of renal mitochondrial integrity in AKI, mice were subjected to sham surgery or varying degrees of ischemia followed by 24 hours of reperfusion. UmtDNA increased in mice after 10-15 minutes of ischemia and positively correlated with ischemia time. Furthermore, UmtDNA was predictive of AKI in the mouse model. Finally, UmtDNA levels were negatively correlated with renal cortical mtDNA and mitochondrial gene expression. These translational studies demonstrate that UmtDNA is associated with recovery from AKI following cardiac surgery by serving as an indicator of mitochondrial integrity. Thus, UmtDNA may serve as valuable biomarker for the development of mitochondrial targeted therapies in AKI. PMID:26287315

  18. Genetics Home Reference: MPV17-related hepatocerebral mitochondrial DNA depletion syndrome

    MedlinePlus

    ... mitochondrial DNA depletion syndrome MPV17-related hepatocerebral mitochondrial DNA depletion syndrome Enable Javascript to view the expand/ ... All Close All Description MPV17 -related hepatocerebral mitochondrial DNA depletion syndrome is an inherited disorder that can ...

  19. The little big genome: the organization of mitochondrial DNA

    PubMed Central

    Garcia, Iraselia; Jones, Edith; Ramos, Manuel; Innis-Whitehouse, Wendy; Gilkerson, Robert

    2017-01-01

    The small (16,569 base pair) human mitochondrial genome plays a significant role in cell metabolism and homeostasis. Mitochondrial DNA (mtDNA) contributes to the generation of complexes which are essential to oxidative phosphorylation (OXPHOS). As such, mtDNA is directly integrated into mitochondrial biogenesis and signaling and regulates mitochondrial metabolism in concert with nuclear-encoded mitochondrial factors. Mitochondria are a highly dynamic, pleiomorphic network that undergoes fission and fusion events. Within this network, mtDNAs are packaged into structures called nucleoids which are actively distributed in discrete foci within the network. This sensitive organelle is frequently disrupted by insults such as oxidants and inflammatory cytokines, and undergoes genomic damage with double- and single-strand breaks that impair its function. Collectively, mtDNA is emerging as a highly sensitive indicator of cellular stress, which is directly integrated into the mitochondrial network as a contributor of a wide range of critical signaling pathways. PMID:27814641

  20. Mitochondrial DNA: impacting central and peripheral nervous systems

    PubMed Central

    Carelli, Valerio

    2014-01-01

    Because of their high-energy metabolism, neurons are highly dependent on mitochondria, which generate cellular ATP through oxidative phosphorylation. The mitochondrial genome encodes for critical components of the oxidative phosphorylation pathway machinery, and therefore mutations in mitochondrial DNA (mtDNA) cause energy production defects that frequently have severe neurological manifestations. Here, we review the principles of mitochondrial genetics and focus on prototypical mitochondrial diseases to illustrate how primary defects in mtDNA or secondary defects in mtDNA due to nuclear genome mutations can cause prominent neurological and multisystem features. In addition, we discuss the pathophysiological mechanisms underlying mitochondrial diseases, the cellular mechanisms that protect mitochondrial integrity, and the prospects for therapy. PMID:25521375

  1. Commentary: Mitochondrial DNA damage and loss in diabetes

    PubMed Central

    Gilkerson, Robert

    2017-01-01

    This commentary discusses damage and loss of mitochondrial DNA (mtDNA) in type 2 diabetes mellitus from both the clinical and experimental perspectives. Increasingly, an array of studies in experimental models and patients suggests that the cellular stresses of insulin resistance in type 2 diabetes damage mtDNA, leading to loss of mitochondrial genetic content. As such, mtDNA is emerging as both a valuable monitoring tool and translational preventive target for metabolic disease. PMID:27253402

  2. Laser controlled singlet oxygen generation in mitochondria to promote mitochondrial DNA replication in vitro.

    PubMed

    Zhou, Xin; Wang, Yupei; Si, Jing; Zhou, Rong; Gan, Lu; Di, Cuixia; Xie, Yi; Zhang, Hong

    2015-11-18

    Reports have shown that a certain level of reactive oxygen species (ROS) can promote mitochondrial DNA (mtDNA) replication. However, it is unclear whether it is the mitochondrial ROS that stimulate mtDNA replication and this requires further investigation. Here we employed a photodynamic system to achieve controlled mitochondrial singlet oxygen ((1)O2) generation. HeLa cells incubated with 5-aminolevulinic acid (ALA) were exposed to laser irradiation to induce (1)O2 generation within mitochondria. Increased mtDNA copy number was detected after low doses of 630 nm laser light in ALA-treated cells. The stimulated mtDNA replication was directly linked to mitochondrial (1)O2 generation, as verified using specific ROS scavengers. The stimulated mtDNA replication was regulated by mitochondrial transcription factor A (TFAM) and mtDNA polymerase γ. MtDNA control region modifications were induced by (1)O2 generation in mitochondria. A marked increase in 8-Oxoguanine (8-oxoG) level was detected in ALA-treated cells after irradiation. HeLa cell growth stimulation and G1-S cell cycle transition were also observed after laser irradiation in ALA-treated cells. These cellular responses could be due to a second wave of ROS generation detected in mitochondria. In summary, we describe a controllable method of inducing mtDNA replication in vitro.

  3. Mitochondrial DNA analysis of ancient Peruvian highlanders.

    PubMed

    Shinoda, Ken-ichi; Adachi, Noboru; Guillen, Sonia; Shimada, Izumi

    2006-09-01

    Ancient DNA recovered from 57 individuals excavated by Hiram Bingham at the rural communities of Paucarcancha, Patallacta, and Huata near the famed Inca royal estate and ritual site of Machu Picchu was analyzed by polymerase chain reaction, and the results were compared with ancient and modern DNA from various Central Andean areas to test their hypothesized indigenous highland origins. The control and coding regions of the mitochondrial DNA (mtDNA) of 35 individuals in this group were sequenced, and the haplogroups of each individual were determined. The frequency data for the haplogroups of these samples show clear proximity to those of modern Quechua and Aymara populations in the Peruvian and Bolivian highlands, and contrast with those of pre-Hispanic individuals of the north coast of Peru that we defined previously. Our study suggests a strong genetic affinity between sampled late pre-Hispanic individuals and modern Andean highlanders. A previous analysis of the Machu Picchu osteological collection suggests that the residents there were a mixed group of natives from various coastal and highland regions relocated by the Inca state for varied purposes. Overall, our study indicates that the sampled individuals from Paucarcancha and Patallacta were indigenous highlanders who provided supportive roles for nearby Machu Picchu. 2006 Wiley-Liss, Inc.

  4. Mitochondrial DNA affinity of several Jewish communities.

    PubMed

    Ritte, U; Neufeld, E; Prager, E M; Gross, M; Hakim, I; Khatib, A; Bonné-Tamir, B

    1993-06-01

    The mitochondrial DNA (mtDNA) of 332 individuals from Israel, including 270 Jews (originating from 7 communities) and 62 Arabs, was analyzed. Each mtDNA haplotype was determined by the fragment patterns of restriction enzymes HpaI, BamHI, HaeII, MspI (HpaII), and AvaII. The variability of the total sample and of each community was high. Of 40 different haplotypes, 20 were found more than once. Most haplotypes are typical of Caucasians, but African types were found among Ethiopian Jews and to a lesser extent among Arabs. The communities differed in their haplotypes: Chi-square tests among six communities showed significant differences for most pairwise comparisons and nonsignificant differences involving mainly the Moroccan Jews. In a genetic distance analysis only the Ethiopian Jews appeared to be distinguished from the other communities. According to a GST analysis, approximately 30% of the variation among the mtDNA restriction maps is attributable to differences between communities.

  5. Taenia hydatigena: isolation of mitochondrial DNA, molecular cloning, and physical mitochondrial genome mapping.

    PubMed

    Yap, K W; Thompson, R C; Rood, J I; Pawlowski, I D

    1987-06-01

    Mitochondrial DNA was isolated from Taenia hydatigena, T. crassiceps, and Echinococcus granulosus using a cetyltrimethylammonium bromide precipitation technique. The technique is simple, rapid, reproducible, and does not require extensive high speed ultracentrifugation. The advantage of using mitochondrial DNA from taeniid cestodes for comparative restriction analysis was demonstrated. Mitochondrial DNA of T. hydatigena was isolated as covalently closed circular molecules. These were linearized by single digestion with BamHI and the molecular weight was estimated from the linear form of 17.6 kb. The mitochondrial DNA of T. hydatigena is therefore similar in size and structure to that of many other animal species. The entire mitochondrial genome was cloned into pBR322 in Escherichia coli and a restriction map of the recombinant molecule was constructed. The potential of using the cloned mitochondrial genome as a probe in speciation studies as well as for providing functional information on the role of the cestode mitochondrion is discussed.

  6. Recombination of mitochondrial DNA detected in skeletal muscle of individuals with multiple mitochondrial DNA heteroplasmy

    PubMed Central

    Zsurka, Gábor; Kraytsberg, Yevgenia; Kudina, Tatiana; Kornblum, Cornelia; Elger, Christian E.; Khrapko, Konstantin; Kunz, Wolfram S.

    2006-01-01

    Experimental evidence for human mitochondrial DNA (mtDNA) recombination was recently obtained in one exceptional individual with paternal inheritance of mtDNA1 and in an in vitro cell culture system2. Whether mtDNA recombination is a common event in humans remained to be elucidated. To detect mtDNA recombination in human skeletal muscle, we have analyzed the distribution of alleles in individuals with multiple mtDNA heteroplasmy using single-cell PCR and allele-specific PCR. In ten out of ten individuals who harbored a heteroplasmic D-loop mutation and a distantly located tRNA point mutation or a large deletion, we observed a mixture of four allelic combinations (tetraplasmy), a hallmark of recombination. Reassuringly, 12 out of 14 individuals with closely located heteroplasmic D-loop mutation pairs contained a mixture of only three types of mitochondrial genomes (triplasmy), consistent with the absence of recombination between adjacent markers. These findings indicate that mtDNA recombination is common in human skeletal muscle. PMID:16025113

  7. The Mitochondrial DNA Polymerase in Health and Disease

    PubMed Central

    Copeland, William C.

    2014-01-01

    Since mutations in mitochondrial DNA (MtDNA) have been shown to be a cause of many mitochondrial diseases as well as aging, it is important to understand the origin of these mutations and how replication proteins modulate this process. DNA polymerase γ (pol γ) is the polymease that is responsible for replication and repair of mtDNA. Pol γ has three main roles in mtDNA maintanence and mutagenesis. As the only known DNA polymerase in mitochondria, pol γ is required for all replication and repair functions and is the main source of errors produced in our mtDNA. Pol γ is also sensitive to a host of antiviral nucleoside analogs used to treat HIV-1 infections, which can cause an induced mitochondrial toxicity. Finally, the gene for pol γ, POLG, is a genetic locus for several mitochondrial disease with over 150 genetic mutations currently identified. PMID:20012584

  8. Mitochondrial DNA damage induced autophagy, cell death, and disease.

    PubMed

    Van Houten, Bennett; Hunter, Senyene E; Meyer, Joel N

    2016-01-01

    Mammalian mitochondria contain multiple small genomes. While these organelles have efficient base excision removal of oxidative DNA lesions and alkylation damage, many DNA repair systems that work on nuclear DNA damage are not active in mitochondria. What is the fate of DNA damage in the mitochondria that cannot be repaired or that overwhelms the repair system? Some forms of mitochondrial DNA damage can apparently trigger mitochondrial DNA destruction, either via direct degradation or through specific forms of autophagy, such as mitophagy. However, accumulation of certain types of mitochondrial damage, in the absence of DNA ligase III (Lig3) or exonuclease G (EXOG), can directly trigger cell death. This review examines the cellular effects of persistent damage to mitochondrial genomes and discusses the very different cell fates that occur in response to different kinds of damage.

  9. Chronological transition of mitochondrial morphology in Chlamydomonas reinhardtii (Chlorophyceae) poststationary phase growth(1).

    PubMed

    Aoyama, Hiroaki; Kuroiwa, Tsuneyoshi; Nakamura, Soichi

    2013-04-01

    In Chlamydomonas reinhardtii P. A. Dangeard, mitochondrial morphology has been observed during asexual cell division cycle, gamete and zygote formation, zygote maturation, and meiotic stages. However, the chronological transition of mitochondrial morphology after the stationary phase of vegetative growth, defined as the poststationary phase, remains unknown. Here, we examined the mitochondrial morphology in cells cultured for 4 months on agar plates to study mitochondrial dynamics in the poststationary phase. Fluorescence microscopy showed that the intricate thread-like structure of mitochondria gradually changed into a granular structure via fragmentation after the stationary phase in cultures of about 1 week of age. The number of mitochondrial nucleoids decreased from about 30 per cell at 1 week to about five per cell after 4 months of culture. The mitochondrial oxygen consumption decreased exponentially, but the mitochondria retained their membrane potential. The total quantity of mitochondrial DNA (mtDNA) of cells at 4 months decreased to 20% of that at 1 week. However, the mitochondrial genomic DNA length was unchanged, as intermediate lengths were not detected. In cells in which the total mtDNA amount was reduced artificially to 16% after treatment with 5-fluoro-2-deoxyuridine (FdUrd) for 1 week, the mitochondria remained as thread-like structures. The oxygen consumption rate of these cells corresponded to that of untreated cells at 1 week of culture. This suggests that a decrease in mtDNA does not directly induce the fragmentation of mitochondria. The results suggest that during the late poststationary phase, mitochondria converge to a minimum unit of a granular structure with a mitochondrial nucleoid. © 2013 Phycological Society of America.

  10. SCID mice containing muscle with human mitochondrial DNA mutations. An animal model for mitochondrial DNA defects.

    PubMed Central

    Clark, K M; Watt, D J; Lightowlers, R N; Johnson, M A; Relvas, J B; Taanman, J W; Turnbull, D M

    1998-01-01

    Defects of the mitochondrial genome are important causes of disease. Despite major advances in our investigation of patients, there is no effective therapy. Progress in this area is limited by the absence of any animal models in which we can evaluate treatment. To develop such a model we have injected human myoblasts into the tibialis anterior of SCID mice after inducing necrosis. After injection of normal human myoblasts, regenerating fibers expressed human beta-spectrin, confirming they were derived from fusion of human myoblasts. The stability of the muscle fibers was inferred by demonstrating the formation of motor end plates on the regenerating fibers. In addition, we show the presence of human cytochrome c oxidase subunit II, which is encoded by the mitochondrial genome, in the regenerated fibers. After injection of human myoblasts containing either the A8344G or the T8993C heteroplasmic mitochondrial DNA mutations, human beta-spectrin positive fibers were found to contain the mutation at a similar level to the injected myoblasts. These studies highlight the potential value of this model for the study of mitochondrial DNA defects. PMID:9854044

  11. Nuclear responses to depletion of mitochondrial DNA in human cells.

    PubMed

    Li, K; Neufer, P D; Williams, R S

    1995-11-01

    The derivation of human cell lines devoid of mitochondrial (mt) DNA (rho 0) provides an opportunity to study nuclear responses to a chronic impairment of mitochondrial oxidative phosphorylation. Expression of several nuclear genes is induced in human rho 0 cells, including those encoding integral proteins of the mitochondrial inner membrane, intermediate filaments, and ribosomes. In contrast to conditions in which mitochondrial respiration is altered acutely, expression of heat shock proteins and immediate early genes is not induced. Mitochondria from rho 0 cells maintain a transmembrane electrochemical potential and are distributed within the cytoplasm of these cells in a manner indistinguishable from that of wild-type cells. We conclude that a chronic deficiency of mitochondrial oxidative phosphorylation produced by elimination of mtDNA is associated with a different pattern of gene induction than that provoked by other acute or subacute conditions that impair mitochondrial respiration or create energy demands in excess of mitochondrial respiratory capacity.

  12. Isolation and nucleotide sequence of a cDNA clone encoding rat mitochondrial malate dehydrogenase.

    PubMed Central

    Grant, P M; Tellam, J; May, V L; Strauss, A W

    1986-01-01

    We have determined the complete sequence of the rat mitochondrial malate dehydrogenase (mMDH) precursor derived from nucleotide sequence of the cDNA. A single synthetic oligodeoxynucleotide probe was used to screen a rat atrial cDNA library constructed in lambda gt10. A 1.2 kb full-length cDNA clone provided the first complete amino acid sequence of pre-mMDH. The 1014 nucleotide-long open reading frame encodes the 314 residue long mature mMDH protein and a 24 amino acid NH2-terminal extension which directs mitochondrial import and is cleaved from the precursor after import to generate mature mMDH. The amino acid composition of the transit peptide is polar and basic. The pre-mMDH transit peptide shows marked homology with those of two other enzymes targeted to the rat mitochondrial matrix. Images PMID:3755817

  13. Staphylococcus aureus Sepsis Induces Early Renal Mitochondrial DNA Repair and Mitochondrial Biogenesis in Mice

    PubMed Central

    Bartz, Raquel R.; Fu, Ping; Suliman, Hagir B.; Crowley, Stephen D.; MacGarvey, Nancy Chou; Welty-Wolf, Karen; Piantadosi, Claude A.

    2014-01-01

    Acute kidney injury (AKI) contributes to the high morbidity and mortality of multi-system organ failure in sepsis. However, recovery of renal function after sepsis-induced AKI suggests active repair of energy-producing pathways. Here, we tested the hypothesis in mice that Staphyloccocus aureus sepsis damages mitochondrial DNA (mtDNA) in the kidney and activates mtDNA repair and mitochondrial biogenesis. Sepsis was induced in wild-type C57Bl/6J and Cox-8 Gfp-tagged mitochondrial-reporter mice via intraperitoneal fibrin clots embedded with S. aureus. Kidneys from surviving mice were harvested at time zero (control), 24, or 48 hours after infection and evaluated for renal inflammation, oxidative stress markers, mtDNA content, and mitochondrial biogenesis markers, and OGG1 and UDG mitochondrial DNA repair enzymes. We examined the kidneys of the mitochondrial reporter mice for changes in staining density and distribution. S. aureus sepsis induced sharp amplification of renal Tnf, Il-10, and Ngal mRNAs with decreased renal mtDNA content and increased tubular and glomerular cell death and accumulation of protein carbonyls and 8-OHdG. Subsequently, mtDNA repair and mitochondrial biogenesis was evidenced by elevated OGG1 levels and significant increases in NRF-1, NRF-2, and mtTFA expression. Overall, renal mitochondrial mass, tracked by citrate synthase mRNA and protein, increased in parallel with changes in mitochondrial GFP-fluorescence especially in proximal tubules in the renal cortex and medulla. Sub-lethal S. aureus sepsis thus induces widespread renal mitochondrial damage that triggers the induction of the renal mtDNA repair protein, OGG1, and mitochondrial biogenesis as a conspicuous resolution mechanism after systemic bacterial infection. PMID:24988481

  14. Reduction of nuclear encoded enzymes of mitochondrial energy metabolism in cells devoid of mitochondrial DNA.

    PubMed

    Mueller, Edith E; Mayr, Johannes A; Zimmermann, Franz A; Feichtinger, René G; Stanger, Olaf; Sperl, Wolfgang; Kofler, Barbara

    2012-01-20

    Mitochondrial DNA (mtDNA) depletion syndromes are generally associated with reduced activities of oxidative phosphorylation (OXPHOS) enzymes that contain subunits encoded by mtDNA. Conversely, entirely nuclear encoded mitochondrial enzymes in these syndromes, such as the tricarboxylic acid cycle enzyme citrate synthase (CS) and OXPHOS complex II, usually exhibit normal or compensatory enhanced activities. Here we report that a human cell line devoid of mtDNA (HEK293 ρ(0) cells) has diminished activities of both complex II and CS. This finding indicates the existence of a feedback mechanism in ρ(0) cells that downregulates the expression of entirely nuclear encoded components of mitochondrial energy metabolism.

  15. Production of mitochondrial DNA transgenic mice using zygotes.

    PubMed

    Inoue, Kimiko; Ogura, Atsuo; Hayashi, Jun-Ichi

    2002-04-01

    Several animal models of human disease, which have been developed by random or targeted modifications of genomic DNA sequences, have furthered our understanding of pathogenesis and the development of therapeutics. However, these models have not facilitated studies on mitochondrial diseases, since modifications to mitochondrial DNA (mtDNA) sequences are not possible using current recombination techniques. Consequently, information on human mitochondrial diseases is relatively sparse, and issues related to mitochondrial pathogenesis and inheritance remain unresolved. Recently, we reported the development of a new technique to generate mice carrying mutant mtDNA from a mouse cell line. In this report, we describe our techniques in detail, with emphasis on the preparation of donor cytoplasts and the micromanipulative procedures for electrofusion of cytoplasts and recipient zygotes. These steps are critically important for the successful introduction of exogenous mtDNA into embryos, and thereby into animals, so that the mutant mtDNA is efficiently propagated in subsequent generations.

  16. Mathematical Modeling of the Role of Mitochondrial Fusion and Fission in Mitochondrial DNA Maintenance

    PubMed Central

    Tam, Zhi Yang; Gruber, Jan; Halliwell, Barry; Gunawan, Rudiyanto

    2013-01-01

    Accumulation of mitochondrial DNA (mtDNA) mutations has been implicated in a wide range of human pathologies, including neurodegenerative diseases, sarcopenia, and the aging process itself. In cells, mtDNA molecules are constantly turned over (i.e. replicated and degraded) and are also exchanged among mitochondria during the fusion and fission of these organelles. While the expansion of a mutant mtDNA population is believed to occur by random segregation of these molecules during turnover, the role of mitochondrial fusion-fission in this context is currently not well understood. In this study, an in silico modeling approach is taken to investigate the effects of mitochondrial fusion and fission dynamics on mutant mtDNA accumulation. Here we report model simulations suggesting that when mitochondrial fusion-fission rate is low, the slow mtDNA mixing can lead to an uneven distribution of mutant mtDNA among mitochondria in between two mitochondrial autophagic events leading to more stochasticity in the outcomes from a single random autophagic event. Consequently, slower mitochondrial fusion-fission results in higher variability in the mtDNA mutation burden among cells in a tissue over time, and mtDNA mutations have a higher propensity to clonally expand due to the increased stochasticity. When these mutations affect cellular energetics, nuclear retrograde signalling can upregulate mtDNA replication, which is expected to slow clonal expansion of these mutant mtDNA. However, our simulations suggest that the protective ability of retrograde signalling depends on the efficiency of fusion-fission process. Our results thus shed light on the interplay between mitochondrial fusion-fission and mtDNA turnover and may explain the mechanism underlying the experimentally observed increase in the accumulation of mtDNA mutations when either mitochondrial fusion or fission is inhibited. PMID:24146842

  17. Mathematical modeling of the role of mitochondrial fusion and fission in mitochondrial DNA maintenance.

    PubMed

    Tam, Zhi Yang; Gruber, Jan; Halliwell, Barry; Gunawan, Rudiyanto

    2013-01-01

    Accumulation of mitochondrial DNA (mtDNA) mutations has been implicated in a wide range of human pathologies, including neurodegenerative diseases, sarcopenia, and the aging process itself. In cells, mtDNA molecules are constantly turned over (i.e. replicated and degraded) and are also exchanged among mitochondria during the fusion and fission of these organelles. While the expansion of a mutant mtDNA population is believed to occur by random segregation of these molecules during turnover, the role of mitochondrial fusion-fission in this context is currently not well understood. In this study, an in silico modeling approach is taken to investigate the effects of mitochondrial fusion and fission dynamics on mutant mtDNA accumulation. Here we report model simulations suggesting that when mitochondrial fusion-fission rate is low, the slow mtDNA mixing can lead to an uneven distribution of mutant mtDNA among mitochondria in between two mitochondrial autophagic events leading to more stochasticity in the outcomes from a single random autophagic event. Consequently, slower mitochondrial fusion-fission results in higher variability in the mtDNA mutation burden among cells in a tissue over time, and mtDNA mutations have a higher propensity to clonally expand due to the increased stochasticity. When these mutations affect cellular energetics, nuclear retrograde signalling can upregulate mtDNA replication, which is expected to slow clonal expansion of these mutant mtDNA. However, our simulations suggest that the protective ability of retrograde signalling depends on the efficiency of fusion-fission process. Our results thus shed light on the interplay between mitochondrial fusion-fission and mtDNA turnover and may explain the mechanism underlying the experimentally observed increase in the accumulation of mtDNA mutations when either mitochondrial fusion or fission is inhibited.

  18. Maternal inheritance of mitochondrial DNA by diverse mechanisms to eliminate paternal mitochondrial DNA.

    PubMed

    Sato, Miyuki; Sato, Ken

    2013-08-01

    The mitochondrion is an organelle that has its own DNA (mtDNA). Mitochondria play essential roles in energy production and in various cellular processes such as metabolism and signal transduction. In most animals, including humans, although the sperm-derived paternal mitochondria enter the oocyte cytoplasm after fertilization, their mtDNA is never transmitted to the offspring. This pattern of mtDNA inheritance is well known as "maternal inheritance." However, how the paternal mitochondria and mtDNA are eliminated from the cytoplasm of gametes or zygotes remains an enigma. Recently, a variety of mechanisms, including specific nuclease-dependent systems, ubiquitin-proteasome system, and autophagy have been shown to degrade the paternal mtDNA or the paternal mitochondria themselves in order to prevent paternal mtDNA transmission. In this review, we will address the current state of knowledge of the molecular mechanisms underlying the elimination of paternal mtDNA or mitochondrial structures for ensuring the maternal transmission of mtDNA.

  19. Preparation of yeast mitochondrial DNA for direct sequence analysis.

    PubMed

    Valach, Matus; Tomaska, Lubomir; Nosek, Jozef

    2008-08-01

    We describe two simple protocols for preparation of templates for direct sequencing of yeast mitochondrial DNA (mtDNA) by automatic DNA analyzers. The protocols work with a range of yeast species and yield a sufficient quantity and quality of the template DNA. In combination with primer-walking strategy, they can be used either as an alternative or a complementary approach to shot-gun sequencing of random fragment DNA libraries. We demonstrate that the templates are suitable for re-sequencing of the mtDNA for comparative analyses of intraspecific variability of yeast strains as well as for primary determination of the complete mitochondrial genome sequence.

  20. Mitochondrial genome acquisition restores respiratory function and tumorigenic potential of cancer cells without mitochondrial DNA.

    PubMed

    Tan, An S; Baty, James W; Dong, Lan-Feng; Bezawork-Geleta, Ayenachew; Endaya, Berwini; Goodwin, Jacob; Bajzikova, Martina; Kovarova, Jaromira; Peterka, Martin; Yan, Bing; Pesdar, Elham Alizadeh; Sobol, Margarita; Filimonenko, Anatolyj; Stuart, Shani; Vondrusova, Magdalena; Kluckova, Katarina; Sachaphibulkij, Karishma; Rohlena, Jakub; Hozak, Pavel; Truksa, Jaroslav; Eccles, David; Haupt, Larisa M; Griffiths, Lyn R; Neuzil, Jiri; Berridge, Michael V

    2015-01-06

    We report that tumor cells without mitochondrial DNA (mtDNA) show delayed tumor growth, and that tumor formation is associated with acquisition of mtDNA from host cells. This leads to partial recovery of mitochondrial function in cells derived from primary tumors grown from cells without mtDNA and a shorter lag in tumor growth. Cell lines from circulating tumor cells showed further recovery of mitochondrial respiration and an intermediate lag to tumor growth, while cells from lung metastases exhibited full restoration of respiratory function and no lag in tumor growth. Stepwise assembly of mitochondrial respiratory (super)complexes was correlated with acquisition of respiratory function. Our findings indicate horizontal transfer of mtDNA from host cells in the tumor microenvironment to tumor cells with compromised respiratory function to re-establish respiration and tumor-initiating efficacy. These results suggest pathophysiological processes for overcoming mtDNA damage and support the notion of high plasticity of malignant cells.

  1. Modeling of Antigenomic Therapy of Mitochondrial Diseases by Mitochondrially Addressed RNA Targeting a Pathogenic Point Mutation in Mitochondrial DNA*

    PubMed Central

    Tonin, Yann; Heckel, Anne-Marie; Vysokikh, Mikhail; Dovydenko, Ilya; Meschaninova, Mariya; Rötig, Agnès; Munnich, Arnold; Venyaminova, Alya; Tarassov, Ivan; Entelis, Nina

    2014-01-01

    Defects in mitochondrial genome can cause a wide range of clinical disorders, mainly neuromuscular diseases. Presently, no efficient therapeutic treatment has been developed against this class of pathologies. Because most of deleterious mitochondrial mutations are heteroplasmic, meaning that wild type and mutated forms of mitochondrial DNA (mtDNA) coexist in the same cell, the shift in proportion between mutant and wild type molecules could restore mitochondrial functions. Recently, we developed mitochondrial RNA vectors that can be used to address anti-replicative oligoribonucleotides into human mitochondria and thus impact heteroplasmy level in cells bearing a large deletion in mtDNA. Here, we show that this strategy can be also applied to point mutations in mtDNA. We demonstrate that specifically designed RNA molecules containing structural determinants for mitochondrial import and 20-nucleotide sequence corresponding to the mutated region of mtDNA, are able to anneal selectively to the mutated mitochondrial genomes. After being imported into mitochondria of living human cells in culture, these RNA induced a decrease of the proportion of mtDNA molecules bearing a pathogenic point mutation in the mtDNA ND5 gene. PMID:24692550

  2. Proteomic Dissection of the Mitochondrial DNA Metabolism Apparatus in Arabidopsis

    SciTech Connect

    SAlly A. Mackenzie

    2004-01-06

    This study involves the investigation of nuclear genetic components that regulate mitochondrial genome behavior in higher plants. The approach utilizes the advanced plant model system of Arabidopsis thaliana to identify and functionally characterize multiple components of the mitochondrial DNA replication, recombination and mismatch repair system and their interaction partners. The rationale for the research stems from the central importance of mitochondria to overall cellular metabolism and the essential nature of the mitochondrial genome to mitochondrial function. Relatively little is understood about mitochondrial DNA maintenance and transmission in higher eukaryotes, and the higher plant mitochondrial genome displays unique properties and behavior. This investigation has revealed at least three important properties of plant mitochondrial DNA metabolism components. (1) Many are dual targeted to mitochondrial and chloroplasts by novel mechanisms, suggesting that the mitochondria a nd chloroplast share their genome maintenance apparatus. (2)The MSH1 gene, originating as a component of mismatch repair, has evolved uniquely in plants to participate in differential replication of the mitochondrial genome. (3) This mitochondrial differential replication process, termed substoichiometric shifting and also involving a RecA-related gene, appears to represent an adaptive mechanism to expand plant reproductive capacity and is likely present throughout the plant kingdom.

  3. Mitochondrial regulation of cancer associated nuclear DNA methylation

    SciTech Connect

    Xie Chenghui; Naito, Akihiro; Mizumachi, Takatsugu; Evans, Teresa T.; Douglas, Michael G.; Cooney, Craig A.; Fan Chunyang; Higuchi, Masahiro

    2007-12-21

    The onset and progression of cancer is associated with the methylation-dependent silencing of specific genes, however, the mechanism and its regulation have not been established. We previously demonstrated that reduction of mitochondrial DNA content induces cancer progression. Here we found that mitochondrial DNA-deficient LN{rho}0-8 activates the hypermethylation of the nuclear DNA promoters including the promoter CpG islands of the endothelin B receptor, O{sup 6}-methylguanine-DNA methyltransferase, and E-cadherin. These are unmethylated and the corresponding gene products are expressed in the parental LNCaP containing mitochondrial DNA. The absence of mitochondrial DNA induced DNA methyltransferase 1 expression which was responsible for the methylation patterns observed. Inhibition of DNA methyltransferase eliminated hypermethylation and expressed gene products in LN{rho}0-8. These studies demonstrate loss or reduction of mitochondrial DNA resulted in the induction of DNA methyltransferase 1, hypermethylation of the promoters of endothelin B receptor, O{sup 6}-methylguanine-DNA methyltransferase, and E-cadherin, and reduction of the corresponding gene products.

  4. Human mitochondrial DNA: roles of inherited and somatic mutations

    PubMed Central

    Schon, Eric A.; DiMauro, Salvatore; Hirano, Michio

    2014-01-01

    Mutations in the human mitochondrial genome are known to cause an array of diverse disorders, most of which are maternally inherited, and all of which are associated with defects in oxidative energy metabolism. It is now emerging that somatic mutations in mitochondrial DNA (mtDNA) are also linked to other complex traits, including neurodegenerative diseases, ageing and cancer. Here we discuss insights into the roles of mtDNA mutations in a wide variety of diseases, highlighting the interesting genetic characteristics of the mitochondrial genome and challenges in studying its contribution to pathogenesis. PMID:23154810

  5. Mitochondrial transcription factor A in the maintenance of mitochondrial DNA: overview of its multiple roles.

    PubMed

    Kang, Dongchon; Hamasaki, Naotaka

    2005-05-01

    Mitochondria have their own genome, which is essential for proper oxidative phosphorylation needed for a large part of ATP production in a cell. Although mitochondrial DNA-less (rho0) cells can survive under special conditions, the integrity of the mitochondrial genome is critical for survival of multicellular organisms. Mitochondrial transcription factor A (TFAM), originally cloned as transcription factor, is essential for the maintenance of mtDNA. Recently, it has become known that TFAM plays critical roles in multiple aspects to maintain the integrity of mitochondrial DNA: transcription, replication, nucleoid formation, damage sensing, and DNA repair. The effects of TFAM in these aspects are intimately related to each other and to function as a whole for the purpose of maintenance of mtDNA.

  6. Mitochondrial DNA structure in the Arabian Peninsula

    PubMed Central

    2008-01-01

    Background Two potential migratory routes followed by modern humans to colonize Eurasia from Africa have been proposed. These are the two natural passageways that connect both continents: the northern route through the Sinai Peninsula and the southern route across the Bab al Mandab strait. Recent archaeological and genetic evidence have favored a unique southern coastal route. Under this scenario, the study of the population genetic structure of the Arabian Peninsula, the first step out of Africa, to search for primary genetic links between Africa and Eurasia, is crucial. The haploid and maternally inherited mitochondrial DNA (mtDNA) molecule has been the most used genetic marker to identify and to relate lineages with clear geographic origins, as the African Ls and the Eurasian M and N that have a common root with the Africans L3. Results To assess the role of the Arabian Peninsula in the southern route, we genetically analyzed 553 Saudi Arabs using partial (546) and complete mtDNA (7) sequencing, and compared the lineages obtained with those present in Africa, the Near East, central, east and southeast Asia and Australasia. The results showed that the Arabian Peninsula has received substantial gene flow from Africa (20%), detected by the presence of L, M1 and U6 lineages; that an 18% of the Arabian Peninsula lineages have a clear eastern provenance, mainly represented by U lineages; but also by Indian M lineages and rare M links with Central Asia, Indonesia and even Australia. However, the bulk (62%) of the Arabian lineages has a Northern source. Conclusion Although there is evidence of Neolithic and more recent expansions in the Arabian Peninsula, mainly detected by (preHV)1 and J1b lineages, the lack of primitive autochthonous M and N sequences, suggests that this area has been more a receptor of human migrations, including historic ones, from Africa, India, Indonesia and even Australia, than a demographic expansion center along the proposed southern coastal

  7. Mitochondrial DNA structure in the Arabian Peninsula.

    PubMed

    Abu-Amero, Khaled K; Larruga, José M; Cabrera, Vicente M; González, Ana M

    2008-02-12

    Two potential migratory routes followed by modern humans to colonize Eurasia from Africa have been proposed. These are the two natural passageways that connect both continents: the northern route through the Sinai Peninsula and the southern route across the Bab al Mandab strait. Recent archaeological and genetic evidence have favored a unique southern coastal route. Under this scenario, the study of the population genetic structure of the Arabian Peninsula, the first step out of Africa, to search for primary genetic links between Africa and Eurasia, is crucial. The haploid and maternally inherited mitochondrial DNA (mtDNA) molecule has been the most used genetic marker to identify and to relate lineages with clear geographic origins, as the African Ls and the Eurasian M and N that have a common root with the Africans L3. To assess the role of the Arabian Peninsula in the southern route, we genetically analyzed 553 Saudi Arabs using partial (546) and complete mtDNA (7) sequencing, and compared the lineages obtained with those present in Africa, the Near East, central, east and southeast Asia and Australasia. The results showed that the Arabian Peninsula has received substantial gene flow from Africa (20%), detected by the presence of L, M1 and U6 lineages; that an 18% of the Arabian Peninsula lineages have a clear eastern provenance, mainly represented by U lineages; but also by Indian M lineages and rare M links with Central Asia, Indonesia and even Australia. However, the bulk (62%) of the Arabian lineages has a Northern source. Although there is evidence of Neolithic and more recent expansions in the Arabian Peninsula, mainly detected by (preHV)1 and J1b lineages, the lack of primitive autochthonous M and N sequences, suggests that this area has been more a receptor of human migrations, including historic ones, from Africa, India, Indonesia and even Australia, than a demographic expansion center along the proposed southern coastal route.

  8. Mitochondrial DNA Phylogeography of the Norway Rat

    PubMed Central

    Song, Ying; Lan, Zhenjiang; Kohn, Michael H.

    2014-01-01

    Central Eastern Asia, foremost the area bordering northern China and Mongolia, has been thought to be the geographic region where Norway rats (Rattus norvegicus) have originated. However recent fossil analyses pointed to their origin in southern China. Moreover, whereas analyses of fossils dated the species' origin as ∼1.2–1.6 million years ago (Mya), molecular analyses yielded ∼0.5–2.9 Mya. Here, to study the geographic origin of the Norway rat and its spread across the globe we analyzed new and all published mitochondrial DNA cytochrome-b (cyt-b; N = 156) and D-loop (N = 212) sequences representing wild rats from four continents and select inbred strains. Our results are consistent with an origin of the Norway rat in southern China ∼1.3 Mya, subsequent prehistoric differentiation and spread in China and Asia from an initially weakly structured ancestral population, followed by further spread and differentiation across the globe during historic times. The recent spreading occurred mostly from derived European populations rather than from archaic Asian populations. We trace laboratory strains to wild lineages from Europe and North America and these represent a subset of the diversity of the rat; leaving Asian lineages largely untapped as a resource for biomedical models. By studying rats from Europe we made the observation that mtDNA diversity cannot be interpreted without consideration of pest control and, possibly, the evolution of rodenticide resistance. However, demographic models explored by forward-time simulations cannot fully explain the low mtDNA diversity of European rats and lack of haplotype sharing with their source from Asia. Comprehensive nuclear marker analyses of a larger sample of Norway rats representing the world are needed to better resolve the evolutionary history of wild rats and of laboratory rats, as well as to better understand the evolution of anticoagulant resistance. PMID:24586325

  9. Mitochondrial DNA phylogeography of the Norway rat.

    PubMed

    Song, Ying; Lan, Zhenjiang; Kohn, Michael H

    2014-01-01

    Central Eastern Asia, foremost the area bordering northern China and Mongolia, has been thought to be the geographic region where Norway rats (Rattus norvegicus) have originated. However recent fossil analyses pointed to their origin in southern China. Moreover, whereas analyses of fossils dated the species' origin as ∼ 1.2-1.6 million years ago (Mya), molecular analyses yielded ∼ 0.5-2.9 Mya. Here, to study the geographic origin of the Norway rat and its spread across the globe we analyzed new and all published mitochondrial DNA cytochrome-b (cyt-b; N = 156) and D-loop (N = 212) sequences representing wild rats from four continents and select inbred strains. Our results are consistent with an origin of the Norway rat in southern China ∼ 1.3 Mya, subsequent prehistoric differentiation and spread in China and Asia from an initially weakly structured ancestral population, followed by further spread and differentiation across the globe during historic times. The recent spreading occurred mostly from derived European populations rather than from archaic Asian populations. We trace laboratory strains to wild lineages from Europe and North America and these represent a subset of the diversity of the rat; leaving Asian lineages largely untapped as a resource for biomedical models. By studying rats from Europe we made the observation that mtDNA diversity cannot be interpreted without consideration of pest control and, possibly, the evolution of rodenticide resistance. However, demographic models explored by forward-time simulations cannot fully explain the low mtDNA diversity of European rats and lack of haplotype sharing with their source from Asia. Comprehensive nuclear marker analyses of a larger sample of Norway rats representing the world are needed to better resolve the evolutionary history of wild rats and of laboratory rats, as well as to better understand the evolution of anticoagulant resistance.

  10. Chronic Ethanol Consumption Increases Myocardial Mitochondrial DNA Mutations: A Potential Contribution by Mitochondrial Topoisomerases

    PubMed Central

    Laurent, D.; Mathew, J.E.; Mitry, M.; Taft, M.; Force, A.; Edwards, J.G.

    2014-01-01

    Aims: Alcoholic cardiomyopathy (ACM) presents as decreased myocardial contractility, arrhythmias and secondary non-ischemic dilated cardiomyopathy leading to heart failure. Mitochondrial dysfunction is known to have a significant role in the development and complications of ACM. This study investigated if chronic ethanol feeding promoted myocardial mitochondrial topoisomerase dysfunction as one underlying cause of mitochondrial DNA (mtDNA) damage and mitochondrial dysfunction in ACM. Methods: The impact of chronic ethanol exposure on the myocardial mitochondria was examined in both neonatal cardiomyocytes using 50 mM ethanol for 6 days and in rats assigned to control or ethanol feeding groups for 4 months. Results: Chronic ethanol feeding led to significant (P < 0.05) decreases in M-mode Fractional Shortening, ejection fraction, and the cardiac output index as well as increases in Tau. Ethanol feeding promoted mitochondrial dysfunction as evidenced by significantly decreased left ventricle cytochrome oxidase activity and decreases in mitochondrial protein content. Both in rats and in cultured cardiomyocytes, chronic ethanol presentation significantly increased mtDNA damage. Using isolated myocardial mitochondria, both mitochondrial topoisomerase-dependent DNA cleavage and DNA relaxation were significantly altered by ethanol feeding. Conclusion: Chronic ethanol feeding compromised cardiovascular and mitochondrial function as a result of a decline in mtDNA integrity that was in part the consequence of mitochondrial topoisomerase dysfunction. Understanding the regulation of the mitochondrial topoisomerases is critical for protection of mtDNA, not only for the management of alcoholic cardiomyopathy, but also for the many other clinical treatments that targets the topoisomerases in the alcoholic patient. PMID:24852753

  11. Sephardic signature in haplogroup T mitochondrial DNA.

    PubMed

    Bedford, Felice L

    2012-04-01

    A rare combination of mutations within mitochondrial DNA subhaplogroup T2e is identified as affiliated with Sephardic Jews, a group that has received relatively little attention. Four investigations were pursued: Search of the motif in 250 000 control region records across 8 databases, comparison of frequencies of T subhaplogroups (T1, T2b, T2c, T2e, T4, T(*)) across 11 diverse populations, creation of a phylogenic median-joining network from public T2e control region entries, and analysis of one Sephardic mitochondrial full genomic sequence with the motif. It was found that the rare motif belonged only to Sephardic descendents (Turkey, Bulgaria), to inhabitants of North American regions known for secret Spanish-Jewish colonization, or were consistent with Sephardic ancestry. The incidence of subhaplogroup T2e decreased from the Western Arabian Peninsula to Italy to Spain and into Western Europe. The ratio of sister subhaplogroups T2e to T2b was found to vary 40-fold across populations from a low in the British Isles to a high in Saudi Arabia with the ratio in Sephardim more similar to Saudi Arabia, Egypt, and Italy than to hosts Spain and Portugal. Coding region mutations of 2308G and 14499T may locate the Sephardic signature within T2e, but additional samples and reworking of current T2e phylogenetic branch structure is needed. The Sephardic Turkish community has a less pronounced founder effect than some Ashkenazi groups considered singly (eg, Polish), but other comparisons of interest await comparable averaging. Registries of signatures will benefit the study of populations with a large number of smaller-size founders.

  12. Sephardic signature in haplogroup T mitochondrial DNA

    PubMed Central

    Bedford, Felice L

    2012-01-01

    A rare combination of mutations within mitochondrial DNA subhaplogroup T2e is identified as affiliated with Sephardic Jews, a group that has received relatively little attention. Four investigations were pursued: Search of the motif in 250 000 control region records across 8 databases, comparison of frequencies of T subhaplogroups (T1, T2b, T2c, T2e, T4, T*) across 11 diverse populations, creation of a phylogenic median-joining network from public T2e control region entries, and analysis of one Sephardic mitochondrial full genomic sequence with the motif. It was found that the rare motif belonged only to Sephardic descendents (Turkey, Bulgaria), to inhabitants of North American regions known for secret Spanish–Jewish colonization, or were consistent with Sephardic ancestry. The incidence of subhaplogroup T2e decreased from the Western Arabian Peninsula to Italy to Spain and into Western Europe. The ratio of sister subhaplogroups T2e to T2b was found to vary 40-fold across populations from a low in the British Isles to a high in Saudi Arabia with the ratio in Sephardim more similar to Saudi Arabia, Egypt, and Italy than to hosts Spain and Portugal. Coding region mutations of 2308G and 14499T may locate the Sephardic signature within T2e, but additional samples and reworking of current T2e phylogenetic branch structure is needed. The Sephardic Turkish community has a less pronounced founder effect than some Ashkenazi groups considered singly (eg, Polish), but other comparisons of interest await comparable averaging. Registries of signatures will benefit the study of populations with a large number of smaller-size founders. PMID:22108605

  13. Mitofusins and the mitochondrial permeability transition: the potential downside of mitochondrial fusion

    PubMed Central

    Papanicolaou, Kyriakos N.; Phillippo, Matthew M.

    2012-01-01

    Mitofusins (Mfn-1 and Mfn-2) are transmembrane proteins that bind and hydrolyze guanosine 5′-triphosphate to bring about the merging of adjacent mitochondrial membranes. This event is necessary for mitochondrial fusion, a biological process that is critical for organelle function. The broad effects of mitochondrial fusion on cell bioenergetics have been extensively studied, whereas the local effects of mitofusin activity on the structure and integrity of the fusing mitochondrial membranes have received relatively little attention. From the study of fusogenic proteins, theoretical models, and simulations, it has been noted that the fusion of biological membranes is associated with local perturbations on the integrity of the membrane that present in the form of lipidic holes which open on the opposing bilayers. These lipidic holes represent obligate intermediates that make the fusion process thermodynamically more favorable and at the same time induce leakage to the fusing membranes. In this perspectives article we present the relevant evidence selected from a spectrum of membrane fusion/leakage models and attempt to couple this information with observations conducted with cardiac myocytes or mitochondria deficient in Mfn-1 and Mfn-2. More specifically, we argue in favor of a situation whereby mitochondrial fusion in cardiac myocytes is coupled with outer mitochondrial membrane destabilization that is opportunistically employed during the process of mitochondrial permeability transition. We hope that these insights will initiate research on this new hypothesis of mitochondrial permeability transition regulation, a poorly understood mitochondrial function with significant consequences on myocyte survival. PMID:22636681

  14. Mitochondrial transcription factor A (TFAM): roles in maintenance of mtDNA and cellular functions.

    PubMed

    Kang, Dongchon; Kim, Sang Ho; Hamasaki, Naotaka

    2007-01-01

    A growing body of evidence suggests that mammalian mitochondrial DNA takes on higher structure called nucleoid or mitochromosome corresponding to that of nuclear DNA. Mitochondrial transcription factor A (TFAM), which was cloned as a transcription factor for mitochondrial DNA, has known to be essential for the maintenance of mitochondrial DNA. Human TFAM has an ability to bind to DNA in a sequence-independent manner and is abundant enough to cover whole region of mitochondrial DNA, owing to which TFAM stabilizes mitochondrial DNA through formation of nucleoid and regulates (or titrates) the amount of mitochondrial DNA. Overexpression of human TFAM in mice increases the amount of mitochondrial DNA and dramatically ameliorates the cardiac dysfunctions caused by myocardial infarction. The maintenance of integrity of mitochondrial DNA is important for keeping proper cellular functions both under physiological and pathological conditions. TFAM may play a crucial role in maintaining mitochondrial DNA as a main component of the nucleoid.

  15. Mitochondrial DNA Damage as a Peripheral Biomarker for Mitochondrial Toxin Exposure in Rats

    PubMed Central

    Sanders, Laurie H.; Howlett, Evan H.; McCoy, Jennifer

    2014-01-01

    Demonstrating or verifying a current or past exposure to an environmental mitochondrial toxin or toxicant is extraordinarily difficult. Thus, there is a pressing need to develop a biomarker for exposure to environmental mitochondrial inhibitors. Rotenone, an environmental toxicant, is a potent inhibitor of the mitochondrial electron transfer chain. Rotenone specifically inhibits complex I throughout the body and brain, thereby producing systemic mitochondrial impairment. As such, rotenone is a prototypical clinically relevant, environmental mitochondrial toxicant that may be used as an ideal initial platform to develop accessible biomarkers of exposure. The over-arching goal of this work is to explore and validate peripheral (blood and skeletal muscle) DNA damage as a biomarker of mitochondrial toxicant exposure using the rat rotenone model. In this effort, we utilized an extremely sensitive quantitative polymerase chain reaction (QPCR)-based assay that simultaneously allows the assessment of multiple forms of mitochondrial DNA (mtDNA) and nuclear DNA (nDNA) damage. We found mtDNA damage in blood is detected after subclinical rotenone exposure and the damage persists even after complex I activity has returned to normal. With a more sustained rotenone exposure, mtDNA damage is also detected in skeletal muscle, suggesting that mtDNA damage in this tissue simply lags behind blood. Using the QPCR-based assay, we have no evidence for nDNA damage in peripheral tissues after rotenone exposure either acutely or chronically. Overall, these data support the idea that mtDNA damage in peripheral tissues in the rotenone model may provide a biomarker of past or ongoing mitochondrial toxin exposure. PMID:25237061

  16. Mitochondrial DNA exhibits resistance to induced point and deletion mutations

    PubMed Central

    Valente, William J.; Ericson, Nolan G.; Long, Alexandra S.; White, Paul A.; Marchetti, Francesco; Bielas, Jason H.

    2016-01-01

    The accumulation of somatic mitochondrial DNA (mtDNA) mutations contributes to the pathogenesis of human disease. Currently, mitochondrial mutations are largely considered results of inaccurate processing of its heavily damaged genome. However, mainly from a lack of methods to monitor mtDNA mutations with sufficient sensitivity and accuracy, a link between mtDNA damage and mutation has not been established. To test the hypothesis that mtDNA-damaging agents induce mtDNA mutations, we exposed MutaTMMouse mice to benzo[a]pyrene (B[a]P) or N-ethyl-N-nitrosourea (ENU), daily for 28 consecutive days, and quantified mtDNA point and deletion mutations in bone marrow and liver using our newly developed Digital Random Mutation Capture (dRMC) and Digital Deletion Detection (3D) assays. Surprisingly, our results demonstrate mutagen treatment did not increase mitochondrial point or deletion mutation frequencies, despite evidence both compounds increase nuclear DNA mutations and demonstrated B[a]P adduct formation in mtDNA. These findings contradict models of mtDNA mutagenesis that assert the elevated rate of mtDNA mutation stems from damage sensitivity and abridged repair capacity. Rather, our results demonstrate induced mtDNA damage does not readily convert into mutation. These findings suggest robust mitochondrial damage responses repress induced mutations after mutagen exposure. PMID:27550180

  17. Mechanisms of Uniparental Mitochondrial DNA Inheritance in Cryptococcus neoformans.

    PubMed

    Gyawali, Rachana; Lin, Xiaorong

    2011-12-01

    In contrast to the nuclear genome, the mitochondrial genome does not follow Mendelian laws of inheritance. The nuclear genome of meiotic progeny comes from the recombination of both parental genomes, whereas the meiotic progeny could inherit mitochondria from one, the other, or both parents. In fact, one fascinating phenomenon is that mitochondrial DNA in the majority of eukaryotes is inherited from only one particular parent. Typically, such unidirectional and uniparental inheritance of mitochondrial DNA can be explained by the size of the gametes involved in mating, with the larger gamete contributing towards mitochondrial DNA inheritance. However, in the human fungal pathogen Cryptococcus neoformans, bisexual mating involves the fusion of two isogamous cells of mating type (MAT) a and MATα, yet the mitochondrial DNA is inherited predominantly from the MATa parent. Although the exact mechanism underlying such uniparental mitochondrial inheritance in this fungus is still unclear, various hypotheses have been proposed. Elucidating the mechanism of mitochondrial inheritance in this clinically important and genetically amenable eukaryotic microbe will yield insights into general mechanisms that are likely conserved in higher eukaryotes. In this review, we highlight studies on Cryptococcus mitochondrial inheritance and point out some important questions that need to be addressed in the future.

  18. Microangiopathy in the cerebellum of patients with mitochondrial DNA disease

    PubMed Central

    Lax, Nichola Z.; Pienaar, Ilse S.; Reeve, Amy K.; Hepplewhite, Philippa D.; Jaros, Evelyn; Taylor, Robert W.; Kalaria, Raj N.

    2012-01-01

    Neuropathological findings in mitochondrial DNA disease vary and are often dependent on the type of mitochondrial DNA defect. Many reports document neuronal cell loss, demyelination, gliosis and necrotic lesions in post-mortem material. However, previous studies highlight vascular abnormalities in patients harbouring mitochondrial DNA defects, particularly in those with the m.3243A>G mutation in whom stroke-like events are part of the mitochondrial encephalopathy lactic acidosis and stroke-like episodes syndrome. We investigated microangiopathic changes in the cerebellum of 16 genetically and clinically well-defined patients. Respiratory chain deficiency, high levels of mutated mitochondrial DNA and increased mitochondrial mass were present within the smooth muscle cells and endothelial cells comprising the vessel wall in patients. These changes were not limited to those harbouring the m.3243A>G mutation frequently associated with mitochondrial encephalopathy, lactic acidosis and stroke-like episodes, but were documented in patients harbouring m.8344A>G and autosomal recessive polymerase (DNA directed), gamma (POLG) mutations. In 8 of the 16 patients, multiple ischaemic-like lesions occurred in the cerebellar cortex suggestive of vascular smooth muscle cell dysfunction. Indeed, changes in vascular smooth muscle and endothelium distribution and cell size are indicative of vascular cell loss. We found evidence of blood–brain barrier breakdown characterized by plasma protein extravasation following fibrinogen and IgG immunohistochemistry. Reduced immunofluorescence was also observed using markers for endothelial tight junctions providing further evidence in support of blood–brain barrier breakdown. Understanding the structural and functional changes occurring in central nervous system microvessels in patients harbouring mitochondrial DNA defects will provide an important insight into mechanisms of neurodegeneration in mitochondrial DNA disease. Since therapeutic

  19. Molecular Poltergeists: Mitochondrial DNA Copies (numts) in Sequenced Nuclear Genomes

    PubMed Central

    Hazkani-Covo, Einat; Zeller, Raymond M.; Martin, William

    2010-01-01

    The natural transfer of DNA from mitochondria to the nucleus generates nuclear copies of mitochondrial DNA (numts) and is an ongoing evolutionary process, as genome sequences attest. In humans, five different numts cause genetic disease and a dozen human loci are polymorphic for the presence of numts, underscoring the rapid rate at which mitochondrial sequences reach the nucleus over evolutionary time. In the laboratory and in nature, numts enter the nuclear DNA via non-homolgous end joining (NHEJ) at double-strand breaks (DSBs). The frequency of numt insertions among 85 sequenced eukaryotic genomes reveal that numt content is strongly correlated with genome size, suggesting that the numt insertion rate might be limited by DSB frequency. Polymorphic numts in humans link maternally inherited mitochondrial genotypes to nuclear DNA haplotypes during the past, offering new opportunities to associate nuclear markers with mitochondrial markers back in time. PMID:20168995

  20. Changes in mitochondrial adenine nucleotides and in permeability transition in two models of rat liver regeneration.

    PubMed

    Hernández-Muñoz, Rolando; Sánchez-Sevilla, Lourdes; Martínez-Gómez, Alejandro; Dent, Myrna A R

    2003-04-01

    Although enhanced phosphorylative activity can be a requisite for later DNA synthesis during liver regeneration (LR), mitochondrial generation of reactive oxygen species could lead to altered mitochondrial membrane permeability during the prereplicative phase of LR. Therefore, the role of mitochondrial permeability transition (MPT) was evaluated during rat LR, induced by either partial hepatectomy (PH) or after CCl(4) administration. Parameters indicative of mitochondrial function and membrane potentials, those of oxidative stress, and in vivo changes of the intramitochondrial pool of adenine nucleotides were determined. Twelve hours after PH, mitochondrial oxidative and phosphorylative activities and adenosine diphosphate (ADP) content were increased, reaching a maximal peak at 24 hours after surgery (maximal DNA synthesis). Parameters suggestive of oxidant stress were enhanced, but mitochondrial volume and membrane electrical potential remained unaltered. Interestingly, moderate mitochondrial swelling and depolarization were found at later post-PH times (72 hours). In CCl(4)-treated animals, it was found that an active liver cell necrosis delayed mitotic activity and mitochondrial uncoupled respiration. Starting 12 hours after CCl(4) intoxication, a drastic increase of inorganic phosphate occurred within swollen and strongly depolarized mitochondria, suggesting changes in the MPT. Despite expression of messenger RNA (mRNA) for mitochondrial transcription, factor A showed a similar time course in both experimental models. The so-called augmenter liver regeneration was found significantly elevated only in PH rats. In conclusion, onset of MPT could be associated with cell necrosis and inflammation after CCl(4) treatment, whereas this mitochondrial event could constitute a putative effector mechanism, through which growth or inflammatory factors inhibiting cell proliferation could initiate LR termination.

  1. Mitochondrial DNA polymorphisms/haplogroups in hereditary spastic paraplegia.

    PubMed

    Sánchez-Ferrero, Elena; Coto, Eliecer; Corao, Ana I; Díaz, Marta; Gámez, Josep; Esteban, Jesús; Gonzalo, Juan F; Pascual-Pascual, Samuel I; López De Munaín, Adolfo; Morís, Germán; Infante, Jon; Del Castillo, Emilia; Márquez, Celedonio; Alvarez, Victoria

    2012-02-01

    Mitochondrial dysfunction could contribute to the development of spastic paraplegia. Among others, two of the genes implicated in hereditary spastic paraplegia encoded mitochondrial proteins and some of the clinical features frequently found in these patients resemble those observed in patients with mitochondrial DNA (mtDNA) mutations. We investigated the association between common mtDNA polymorphisms and spastic paraplegia. The ten mtDNA polymorphisms that defined the common European haplogroups were determined in 424 patients, 19% with a complicated phenotype. A rare haplogroup was associated with the disease in patients without a SPG3A, SPG4, or SPG7 mutation. Allele 10398G was more frequent among patients with a pure versus complicated phenotype. This mtDNA polymorphism was previously associated with the risk of developing other neurodegenerative diseases. In conclusion, some mtDNA polymorphisms could contribute to the development of spastic paraplegia or act as modifiers of the phenotype.

  2. [Somatic mutations in nuclear and mitochondrial DNA]. Progress report

    SciTech Connect

    Not Available

    1992-09-01

    The study is concerned the design of new assays that may detect rare somatic mutations in nuclear and mitochondrial DNA, which may increase upon exposure to mutagens, and thus become a marker of human exposure to such mutagens. Two assays for somatic mutation were presented, one for mitochondrial DNA deletions which was developed by the author, and one for deletions of the ADA gene which resides in the nucleus.

  3. Mitochondrial DNA sequence evolution in the Arctoidea.

    PubMed Central

    Zhang, Y P; Ryder, O A

    1993-01-01

    Some taxa in the superfamily Arctoidea, such as the giant panda and the lesser panda, have presented puzzles to taxonomists. In the present study, approximately 397 bases of the cytochrome b gene, 364 bases of the 12S rRNA gene, and 74 bases of the tRNA(Thr) and tRNA(Pro) genes from the giant panda, lesser panda, kinkajou, raccoon, coatimundi, and all species of the Ursidae were sequenced. The high transition/transversion ratios in cytochrome b and RNA genes prior to saturation suggest that the presumed transition bias may represent a trend for some mammalian lineages rather than strictly a primate phenomenon. Transversions in the 12S rRNA gene accumulate in arctoids at about half the rate reported for artiodactyls. Different arctoid lineages evolve at different rates: the kinkajou, a procyonid, evolves the fastest, 1.7-1.9 times faster than the slowest lineage that comprises the spectacled and polar bears. Generation-time effect can only partially explain the different rates of nucleotide substitution in arctoids. Our results based on parsimony analysis show that the giant panda is more closely related to bears than to the lesser panda; the lesser panda is neither closely related to bears nor to the New World procyonids. The kinkajou, raccoon, and coatimundi diverged from each other very early, even though they group together. The polar bear is closely related to the spectacled bear, and they began to diverge from a common mitochondrial ancestor approximately 2 million years ago. Relationships of the remaining five bear species are derived. PMID:8415740

  4. Mitochondrial and nuclear DNA matching shapes metabolism and healthy ageing.

    PubMed

    Latorre-Pellicer, Ana; Moreno-Loshuertos, Raquel; Lechuga-Vieco, Ana Victoria; Sánchez-Cabo, Fátima; Torroja, Carlos; Acín-Pérez, Rebeca; Calvo, Enrique; Aix, Esther; González-Guerra, Andrés; Logan, Angela; Bernad-Miana, María Luisa; Romanos, Eduardo; Cruz, Raquel; Cogliati, Sara; Sobrino, Beatriz; Carracedo, Ángel; Pérez-Martos, Acisclo; Fernández-Silva, Patricio; Ruíz-Cabello, Jesús; Murphy, Michael P; Flores, Ignacio; Vázquez, Jesús; Enríquez, José Antonio

    2016-07-28

    Human mitochondrial DNA (mtDNA) shows extensive within population sequence variability. Many studies suggest that mtDNA variants may be associated with ageing or diseases, although mechanistic evidence at the molecular level is lacking. Mitochondrial replacement has the potential to prevent transmission of disease-causing oocyte mtDNA. However, extension of this technology requires a comprehensive understanding of the physiological relevance of mtDNA sequence variability and its match with the nuclear-encoded mitochondrial genes. Studies in conplastic animals allow comparison of individuals with the same nuclear genome but different mtDNA variants, and have provided both supporting and refuting evidence that mtDNA variation influences organismal physiology. However, most of these studies did not confirm the conplastic status, focused on younger animals, and did not investigate the full range of physiological and phenotypic variability likely to be influenced by mitochondria. Here we systematically characterized conplastic mice throughout their lifespan using transcriptomic, proteomic,metabolomic, biochemical, physiological and phenotyping studies. We show that mtDNA haplotype profoundly influences mitochondrial proteostasis and reactive oxygen species generation,insulin signalling, obesity, and ageing parameters including telomere shortening and mitochondrial dysfunction, resulting in profound differences in health longevity between conplastic strains.

  5. Global Genetic Determinants of Mitochondrial DNA Copy Number

    PubMed Central

    Zhang, Hengshan; Singh, Keshav K.

    2014-01-01

    Many human diseases including development of cancer is associated with depletion of mitochondrial DNA (mtDNA) content. These diseases are collectively described as mitochondrial DNA depletion syndrome (MDS). High similarity between yeast and human mitochondria allows genomic study of the budding yeast to be used to identify human disease genes. In this study, we systematically screened the pre-existing respiratory-deficient Saccharomyces cerevisiae yeast strains using fluorescent microscopy and identified 102 nuclear genes whose deletions result in a complete mtDNA loss, of which 52 are not reported previously. Strikingly, these genes mainly encode protein products involved in mitochondrial protein biosynthesis process (54.9%). The rest of these genes either encode protein products associated with nucleic acid metabolism (14.7%), oxidative phosphorylation (3.9%), or other protein products (13.7%) responsible for bud-site selection, mitochondrial intermembrane space protein import, assembly of cytochrome-c oxidase, vacuolar protein sorting, protein-nucleus import, calcium-mediated signaling, heme biosynthesis and iron homeostasis. Thirteen (12.7%) of the genes encode proteins of unknown function. We identified human orthologs of these genes, conducted the interaction between the gene products and linked them to human mitochondrial disorders and other pathologies. In addition, we screened for genes whose defects affect the nuclear genome integrity. Our data provide a systematic view of the nuclear genes involved in maintenance of mitochondrial DNA. Together, our studies i) provide a global view of the genes regulating mtDNA content; ii) provide compelling new evidence toward understanding novel mechanism involved in mitochondrial genome maintenance and iii) provide useful clues in understanding human diseases in which mitochondrial defect and in particular depletion of mitochondrial genome plays a critical role. PMID:25170845

  6. Pathophysiology of mitochondrial volume homeostasis: potassium transport and permeability transition.

    PubMed

    Nowikovsky, Karin; Schweyen, Rudolf J; Bernardi, Paolo

    2009-05-01

    Regulation of mitochondrial volume is a key issue in cellular pathophysiology. Mitochondrial volume and shape changes can occur following regulated fission-fusion events, which are modulated by a complex network of cytosolic and mitochondrial proteins; and through regulation of ion transport across the inner membrane. In this review we will cover mitochondrial volume homeostasis that depends on (i) monovalent cation transport across the inner membrane, a regulated process that couples electrophoretic K(+) influx on K(+) channels to K(+) extrusion through the K(+)-H(+) exchanger; (ii) the permeability transition, a loss of inner membrane permeability that may be instrumental in triggering cell death. Specific emphasis will be placed on molecular advances on the nature of the transport protein(s) involved, and/or on diseases that depend on mitochondrial volume dysregulation.

  7. Mitochondrial DNA Mutations Provoke Dominant Inhibition of Mitochondrial Inner Membrane Fusion

    PubMed Central

    Sauvanet, Cécile; Duvezin-Caubet, Stéphane; Salin, Bénédicte; David, Claudine; Massoni-Laporte, Aurélie; di Rago, Jean-Paul; Rojo, Manuel

    2012-01-01

    Mitochondria are highly dynamic organelles that continuously move, fuse and divide. Mitochondrial dynamics modulate overall mitochondrial morphology and are essential for the proper function, maintenance and transmission of mitochondria and mitochondrial DNA (mtDNA). We have investigated mitochondrial fusion in yeast cells with severe defects in oxidative phosphorylation (OXPHOS) due to removal or various specific mutations of mtDNA. We find that, under fermentative conditions, OXPHOS deficient cells maintain normal levels of cellular ATP and ADP but display a reduced mitochondrial inner membrane potential. We demonstrate that, despite metabolic compensation by glycolysis, OXPHOS defects are associated to a selective inhibition of inner but not outer membrane fusion. Fusion inhibition was dominant and hampered the fusion of mutant mitochondria with wild-type mitochondria. Inhibition of inner membrane fusion was not systematically associated to changes of mitochondrial distribution and morphology, nor to changes in the isoform pattern of Mgm1, the major fusion factor of the inner membrane. However, inhibition of inner membrane fusion correlated with specific alterations of mitochondrial ultrastructure, notably with the presence of aligned and unfused inner membranes that are connected to two mitochondrial boundaries. The fusion inhibition observed upon deletion of OXPHOS related genes or upon removal of the entire mtDNA was similar to that observed upon introduction of point mutations in the mitochondrial ATP6 gene that are associated to neurogenic ataxia and retinitis pigmentosa (NARP) or to maternally inherited Leigh Syndrome (MILS) in humans. Our findings indicate that the consequences of mtDNA mutations may not be limited to OXPHOS defects but may also include alterations in mitochondrial fusion. Our results further imply that, in healthy cells, the dominant inhibition of fusion could mediate the exclusion of OXPHOS-deficient mitochondria from the network of

  8. Mitochondrial DNA mutations provoke dominant inhibition of mitochondrial inner membrane fusion.

    PubMed

    Sauvanet, Cécile; Duvezin-Caubet, Stéphane; Salin, Bénédicte; David, Claudine; Massoni-Laporte, Aurélie; di Rago, Jean-Paul; Rojo, Manuel

    2012-01-01

    Mitochondria are highly dynamic organelles that continuously move, fuse and divide. Mitochondrial dynamics modulate overall mitochondrial morphology and are essential for the proper function, maintenance and transmission of mitochondria and mitochondrial DNA (mtDNA). We have investigated mitochondrial fusion in yeast cells with severe defects in oxidative phosphorylation (OXPHOS) due to removal or various specific mutations of mtDNA. We find that, under fermentative conditions, OXPHOS deficient cells maintain normal levels of cellular ATP and ADP but display a reduced mitochondrial inner membrane potential. We demonstrate that, despite metabolic compensation by glycolysis, OXPHOS defects are associated to a selective inhibition of inner but not outer membrane fusion. Fusion inhibition was dominant and hampered the fusion of mutant mitochondria with wild-type mitochondria. Inhibition of inner membrane fusion was not systematically associated to changes of mitochondrial distribution and morphology, nor to changes in the isoform pattern of Mgm1, the major fusion factor of the inner membrane. However, inhibition of inner membrane fusion correlated with specific alterations of mitochondrial ultrastructure, notably with the presence of aligned and unfused inner membranes that are connected to two mitochondrial boundaries. The fusion inhibition observed upon deletion of OXPHOS related genes or upon removal of the entire mtDNA was similar to that observed upon introduction of point mutations in the mitochondrial ATP6 gene that are associated to neurogenic ataxia and retinitis pigmentosa (NARP) or to maternally inherited Leigh Syndrome (MILS) in humans. Our findings indicate that the consequences of mtDNA mutations may not be limited to OXPHOS defects but may also include alterations in mitochondrial fusion. Our results further imply that, in healthy cells, the dominant inhibition of fusion could mediate the exclusion of OXPHOS-deficient mitochondria from the network of

  9. Commentary: Mitochondrial DNA damage and loss in diabetes.

    PubMed

    Gilkerson, Robert

    2016-10-01

    This commentary discusses damage and loss of mitochondrial DNA (mtDNA) in type 2 diabetes mellitus from both the clinical and experimental perspectives. Increasingly, an array of studies in experimental models and patients suggests that the cellular stresses of insulin resistance in type 2 diabetes damage mtDNA, leading to loss of mitochondrial genetic content. As such, mtDNA is emerging as both a valuable monitoring tool and translational preventive target for metabolic disease. Copyright © 2016 John Wiley & Sons, Ltd.

  10. RECQL4 LOCALIZES TO MITOCHONDRIA AND PRESERVES MITOCHONDRIAL DNA INTEGRITY

    PubMed Central

    Croteau, Deborah L.; Rossi, Marie L.; Canugovi, Chandrika; Tian, Jane; Sykora, Peter; Ramamoorthy, Mahesh; Wang, ZhengMing; Singh, Dharmendra Kumar; Akbari, Mansour; Kasiviswanathan, Rajesh; Copeland, William C.; Bohr, Vilhelm A.

    2012-01-01

    SUMMARY RECQL4 is associated with Rothmund-Thomson Syndrome (RTS), a rare autosomal recessive disorder characterized by premature aging, genomic instability and cancer predisposition. RECQL4 is a member of the RecQ-helicase family, and has many similarities to WRN protein, which is also implicated in premature aging. There is no information about whether any of the RecQ helicases play roles in mitochondrial biogenesis, which is strongly implicated in the aging process. Here, we used microscopy to visualize RECQL4 in mitochondria. Fractionation of human and mouse cells also showed that RECQL4 was present in mitochondria. Q-PCR amplification of mitochondrial DNA demonstrated that mtDNA damage accumulated in RECQL4-deficient cells. Microarray analysis suggested that mitochondrial bioenergetic pathways might be affected in RTS. Measurements of mitochondrial bioenergetics showed a reduction in the mitochondrial reserve capacity after lentiviral knockdown of RECQL4 in two different primary cell lines. Additionally, biochemical assays with RECQL4, mitochondrial transcription factor A and mitochondrial DNA polymerase γ showed that the polymerase inhibited RECQL4’s helicase activity. RECQL4 is the first 3′ to 5′ RecQ helicase to be found in both human and mouse mitochondria and the loss of RECQL4 alters mitochondrial integrity. PMID:22296597

  11. Mutations in mitochondrial DNA causing tubulointerstitial kidney disease

    PubMed Central

    Mallett, Andrew; Posse, Viktor; Moreno, Pablo; Sciacovelli, Marco; Duff, Jennifer; Wiesener, Michael S.; Hudson, Gavin; Gustafsson, Claes M.; Chinnery, Patrick F.; Maxwell, Patrick H.

    2017-01-01

    Tubulointerstitial kidney disease is an important cause of progressive renal failure whose aetiology is incompletely understood. We analysed a large pedigree with maternally inherited tubulointerstitial kidney disease and identified a homoplasmic substitution in the control region of the mitochondrial genome (m.547A>T). While mutations in mtDNA coding sequence are a well recognised cause of disease affecting multiple organs, mutations in the control region have never been shown to cause disease. Strikingly, our patients did not have classical features of mitochondrial disease. Patient fibroblasts showed reduced levels of mitochondrial tRNAPhe, tRNALeu1 and reduced mitochondrial protein translation and respiration. Mitochondrial transfer demonstrated mitochondrial transmission of the defect and in vitro assays showed reduced activity of the heavy strand promoter. We also identified further kindreds with the same phenotype carrying a homoplasmic mutation in mitochondrial tRNAPhe (m.616T>C). Thus mutations in mitochondrial DNA can cause maternally inherited renal disease, likely mediated through reduced function of mitochondrial tRNAPhe. PMID:28267784

  12. Oxidative DNA damage causes mitochondrial genomic instability in Saccharomyces cerevisiae.

    PubMed

    Doudican, Nicole A; Song, Binwei; Shadel, Gerald S; Doetsch, Paul W

    2005-06-01

    Mitochondria contain their own genome, the integrity of which is required for normal cellular energy metabolism. Reactive oxygen species (ROS) produced by normal mitochondrial respiration can damage cellular macromolecules, including mitochondrial DNA (mtDNA), and have been implicated in degenerative diseases, cancer, and aging. We developed strategies to elevate mitochondrial oxidative stress by exposure to antimycin and H(2)O(2) or utilizing mutants lacking mitochondrial superoxide dismutase (sod2Delta). Experiments were conducted with strains compromised in mitochondrial base excision repair (ntg1Delta) and oxidative damage resistance (pif1Delta) in order to delineate the relationship between these pathways. We observed enhanced ROS production, resulting in a direct increase in oxidative mtDNA damage and mutagenesis. Repair-deficient mutants exposed to oxidative stress conditions exhibited profound genomic instability. Elimination of Ntg1p and Pif1p resulted in a synergistic corruption of respiratory competency upon exposure to antimycin and H(2)O(2). Mitochondrial genomic integrity was substantially compromised in ntg1Delta pif1Delta sod2Delta strains, since these cells exhibit a total loss of mtDNA. A stable respiration-defective strain, possessing a normal complement of mtDNA damage resistance pathways, exhibited a complete loss of mtDNA upon exposure to antimycin and H(2)O(2). This loss was preventable by Sod2p overexpression. These results provide direct evidence that oxidative mtDNA damage can be a major contributor to mitochondrial genomic instability and demonstrate cooperation of Ntg1p and Pif1p to resist the introduction of lesions into the mitochondrial genome.

  13. Human mitochondrial transcription factor A is required for the segregation of mitochondrial DNA in cultured cells.

    PubMed

    Kasashima, Katsumi; Sumitani, Megumi; Endo, Hitoshi

    2011-01-15

    The segregation and transmission of the mitochondrial genome in humans are complicated processes but are particularly important for understanding the inheritance and clinical abnormalities of mitochondrial disorders. However, the molecular mechanism of the segregation of mitochondrial DNA (mtDNA) is largely unclear. In this study, we demonstrated that human mitochondrial transcription factor A (TFAM) is required for the segregation of mtDNA in cultured cells. RNAi-mediated knockdown of TFAM in HeLa cells resulted in the enlarged mtDNA, as indicated by the assembly of fluorescent signals stained with PicoGreen. Fluorescent in situ hybridization confirmed the enlarged mtDNA and further showed the existence of increased numbers of mitochondria lacking mtDNA signals in TFAM knockdown cells. By complementation analysis, the C-terminal tail of TFAM, which enhances its affinity with DNA, was found to be required for the appropriate distribution of mtDNA. Furthermore, we found that TFAM knockdown induced asymmetric segregation of mtDNA between dividing daughter cells. These results suggest an essential role for human TFAM in symmetric segregation of mtDNA.

  14. Loss of mitochondrial DNA with aging in Drosophila melanogaster.

    PubMed

    Massie, H R; Baird, M B; McMahon, M M

    1975-01-01

    The buoyant densities of nuclear and mitochondrial DNA from Drosophila melanogaster lysates has been found to show no change with increasing age in both CsCl and Cs2SO4 equilibrium density gradients. Whole fly homogenates were used to demonstrate no change in nuclear DNA content during adult life. Mitochondrial DNA increased from 1.2 to 4.3% of the total DNA during the first week of adult life and then decreased during senescence to a minimum of 1.5% at 10 weeks of age which represented a 65% loss in mitochondrial DNA content with age. These data are interpreted to support the proposal that mitochondria destruction occurs during senescence.

  15. Mitochondrial DNA damage and the aging process: facts and imaginations.

    PubMed

    Wiesner, Rudolf J; Zsurka, Gábor; Kunz, Wolfram S

    2006-12-01

    Mitochondrial DNA (mtDNA) is a circular double-stranded molecule organized in nucleoids and covered by the histone-like protein mitochondrial transcription factor A (TFAM). Even though mtDNA repair capacity appears to be adequate the accumulation of mtDNA mutations has been shown to be at least one important molecular mechanism of human aging. Reactive oxygen species (ROS), which are generated at the FMN moiety of mitochondrial respiratory chain (RC) complex I, should be considered to be important at least for the generation of age-dependent mtDNA deletions. However, the accumulation of acquired mutations to functionally relevant levels in aged tissues seems to be a consequence of clonal expansions of single founder molecules and not of ongoing mutational events.

  16. Mitochondrial DNA variation in human radiation and disease.

    PubMed

    Wallace, Douglas C

    2015-09-24

    Environmental adaptation, predisposition to common diseases, and, potentially, speciation may all be linked through the adaptive potential of mitochondrial DNA (mtDNA) alterations of bioenergetics. This Perspective synthesizes evidence that human mtDNA variants may be adaptive or deleterious depending on environmental context and proposes that the accrual of mtDNA variation could contribute to animal speciation via adaptation to marginal environments.

  17. Oxidized mitochondrial DNA activates the NLRP3 inflammasome during apoptosis.

    PubMed

    Shimada, Kenichi; Crother, Timothy R; Karlin, Justin; Dagvadorj, Jargalsaikhan; Chiba, Norika; Chen, Shuang; Ramanujan, V Krishnan; Wolf, Andrea J; Vergnes, Laurent; Ojcius, David M; Rentsendorj, Altan; Vargas, Mario; Guerrero, Candace; Wang, Yinsheng; Fitzgerald, Katherine A; Underhill, David M; Town, Terrence; Arditi, Moshe

    2012-03-23

    We report that in the presence of signal 1 (NF-κB), the NLRP3 inflammasome was activated by mitochondrial apoptotic signaling that licensed production of interleukin-1β (IL-1β). NLRP3 secondary signal activators such as ATP induced mitochondrial dysfunction and apoptosis, resulting in release of oxidized mitochondrial DNA (mtDNA) into the cytosol, where it bound to and activated the NLRP3 inflammasome. The antiapoptotic protein Bcl-2 inversely regulated mitochondrial dysfunction and NLRP3 inflammasome activation. Mitochondrial DNA directly induced NLRP3 inflammasome activation, because macrophages lacking mtDNA had severely attenuated IL-1β production, yet still underwent apoptosis. Both binding of oxidized mtDNA to the NLRP3 inflammasome and IL-1β secretion could be competitively inhibited by the oxidized nucleoside 8-OH-dG. Thus, our data reveal that oxidized mtDNA released during programmed cell death causes activation of the NLRP3 inflammasome. These results provide a missing link between apoptosis and inflammasome activation, via binding of cytosolic oxidized mtDNA to the NLRP3 inflammasome.

  18. Oxidized Mitochondrial DNA Activates the NLRP3 Inflammasome During Apoptosis

    PubMed Central

    Shimada, Kenichi; Crother, Timothy R.; Karlin, Justin; Dagvadorj, Jargalsaikhan; Chiba, Norika; Chen, Shuang; Ramanujan, V. Krishnan; Wolf, Andrea J.; Vergnes, Laurent; Ojcius, David M.; Rentsendorj, Altan; Vargas, Mario; Guerrero, Candace; Wang, Yinsheng; Fitzgerald, Katherine A.; Underhill, David M.; Town, Terrence; Arditi, Moshe

    2012-01-01

    SUMMARY We report that in the presence of signal 1 (NF-κB), the NLRP3 inflammasome was activated by mitochondrial apoptotic signaling that licensed production of interleukin-1β (IL-1β). NLRP3 secondary signal activators such as ATP induced mitochondrial dysfunction and apoptosis, resulting in release of oxidized mitochondrial DNA (mtDNA) into the cytosol, where it bound to and activated the NLRP3 inflammasome. The anti-apoptotic protein Bcl-2 inversely regulated mitochondrial dysfunction and NLRP3 inflammasome activation. Mitochondrial DNA directly induced NLRP3 inflammasome activation, because macrophages lacking mtDNA had severely attenuated IL-1β production, yet still underwent apoptosis. Both binding of oxidized mtDNA to the NLRP3 inflammasome and IL-1β secretion could be competitively inhibited by the oxidized nucleoside, 8-OH-dG. Thus, our data reveal that oxidized mtDNA released during programmed cell death causes activation of the NLRP3 inflammasome. These results provide a missing link between apoptosis and inflammasome activation, via binding of cytosolic oxidized mtDNA to the NLRP3 inflammasome. PMID:22342844

  19. An autoradiographic demonstration of nuclear DNA replication by DNA polymerase alpha and of mitochondrial DNA synthesis by DNA polymerase gamma.

    PubMed Central

    Geuskens, M; Hardt, N; Pedrali-Noy, G; Spadari, S

    1981-01-01

    The incorporation of thymidine into the DNA of eukaryotic cells is markedly depressed, but not completely inhibited, by aphidicolin, a highly specific inhibitor of DNA polymerase alpha. An electron microscope autoradiographic analysis of the synthesis of nuclear and mitochondrial DNA in vivo in Concanavalin A stimulated rabbit spleen lymphocytes and in Hamster cell cultures, in the absence and in the presence of aphidicolin, revealed that aphidicolin inhibits the nuclear but not the mitochondrial DNA replication. We therefore conclude that DNA polymerase alpha performs the synchronous bidirectional replication of nuclear DNA and that DNA polymerase gamma, the only DNA polymerase present in the mitochondria, performs the "strand displacement" DNA synthesis of these organelles. Images PMID:6262734

  20. Mitochondrial DNA triplication and punctual mutations in patients with mitochondrial neuromuscular disorders.

    PubMed

    Mkaouar-Rebai, Emna; Felhi, Rahma; Tabebi, Mouna; Alila-Fersi, Olfa; Chamkha, Imen; Maalej, Marwa; Ammar, Marwa; Kammoun, Fatma; Keskes, Leila; Hachicha, Mongia; Fakhfakh, Faiza

    2016-04-29

    Mitochondrial diseases are a heterogeneous group of disorders caused by the impairment of the mitochondrial oxidative phosphorylation system which have been associated with various mutations of the mitochondrial DNA (mtDNA) and nuclear gene mutations. The clinical phenotypes are very diverse and the spectrum is still expanding. As brain and muscle are highly dependent on OXPHOS, consequently, neurological disorders and myopathy are common features of mtDNA mutations. Mutations in mtDNA can be classified into three categories: large-scale rearrangements, point mutations in tRNA or rRNA genes and point mutations in protein coding genes. In the present report, we screened mitochondrial genes of complex I, III, IV and V in 2 patients with mitochondrial neuromuscular disorders. The results showed the presence the pathogenic heteroplasmic m.9157G>A variation (A211T) in the MT-ATP6 gene in the first patient. We also reported the first case of triplication of 9 bp in the mitochondrial NC7 region in Africa and Tunisia, in association with the novel m.14924T>C in the MT-CYB gene in the second patient with mitochondrial neuromuscular disorder.

  1. Mitochondrial permeability transition pore induces mitochondria injury in Huntington disease.

    PubMed

    Quintanilla, Rodrigo A; Jin, Youngnam N; von Bernhardi, Rommy; Johnson, Gail V W

    2013-12-11

    Mitochondrial impairment has been implicated in the pathogenesis of Huntington's disease (HD). However, how mutant huntingtin impairs mitochondrial function and thus contributes to HD has not been fully elucidated. In this study, we used striatal cells expressing wild type (STHdhQ7/Q7) or mutant (STHdhQ111/Q111) huntingtin protein, and cortical neurons expressing the exon 1 of the huntingtin protein with physiological or pathological polyglutamine domains, to examine the interrelationship among specific mitochondrial functions. Depolarization induced by KCl resulted in similar changes in calcium levels without compromising mitochondrial function, both in wild type and mutant cells. However, treatment of mutant cells with thapsigargin (a SERCA antagonist that raises cytosolic calcium levels), resulted in a pronounced decrease in mitochondrial calcium uptake, increased production of reactive oxygen species (ROS), mitochondrial depolarization and fragmentation, and cell viability loss. The mitochondrial dysfunction in mutant cells was also observed in cortical neurons expressing exon 1 of the huntingtin protein with 104 Gln residues (Q104-GFP) when they were exposed to calcium stress. In addition, calcium overload induced opening of the mitochondrial permeability transition pore (mPTP) in mutant striatal cells. The mitochondrial impairment observed in mutant cells and cortical neurons expressing Q104-GFP was prevented by pre-treatment with cyclosporine A (CsA) but not by FK506 (an inhibitor of calcineurin), indicating a potential role for mPTP opening in the mitochondrial dysfunction induced by calcium stress in mutant huntingtin cells. Expression of mutant huntingtin alters mitochondrial and cell viability through mPTP opening in striatal cells and cortical neurons.

  2. Mutations in circulating mitochondrial DNA: Cassandra of oral cancer?

    PubMed

    Kandel, Eugene S

    2012-07-01

    Cell-free circulating nucleic acids in human blood are increasing being researched as a source of diagnostic and prognostic biomarkers for clinical oncology. High copy number per cell and frequent mutations in various malignancies make mitochondrial genome an attractive target for such an investigation, but practical development and validation of biomarkers based on cell-free mitochondrial DNA has been lagging. Uzawa and colleagues report in the July issue of Oncotarget that in a retrospective study of patients with oral cancer the load of mutant mitochondrial DNA in patient's serum was a strong indicator of postoperative recurrence. Based on these observations, the predictive value of circulating mutant mitochondrial DNA merits further evaluation in patients with oral and other malignancies.

  3. A peep into mitochondrial disorder: multifaceted from mitochondrial DNA mutations to nuclear gene modulation.

    PubMed

    Chen, Chao; Chen, Ye; Guan, Min-Xin

    2015-12-01

    Mitochondrial genome is responsible for multiple human diseases in a maternal inherited pattern, yet phenotypes of patients in a same pedigree frequently vary largely. Genes involving in epigenetic modification, RNA processing, and other biological pathways, rather than "threshold effect" and environmental factors, provide more specific explanation to the aberrant phenotype. Thus, the double hit theory, mutations both in mitochondrial DNA and modifying genes aggravating the symptom, throws new light on mitochondrial dysfunction processes. In addition, mitochondrial retrograde signaling pathway that leads to reconfiguration of cell metabolism to adapt defects in mitochondria may as well play an active role. Here we review selected examples of modifier genes and mitochondrial retrograde signaling in mitochondrial disorders, which refine our understanding and will guide the rational design of clinical therapies.

  4. DNA Compaction by Yeast Mitochondrial Protein ABF2p

    SciTech Connect

    Friddle, R W; Klare, J E; Noy, A; Corzett, M; Balhorn, R; Baskin, R J; Martin, S S; Baldwin, E P

    2003-05-09

    We used high resolution Atomic Force Microscopy (AFM) to image compaction of linear and circular DNA by the yeast mitochondrial protein ABF2p , which plays a major role in maintaining mitochondrial DNA. AFM images show that protein binding induces drastic bends in the DNA backbone for both linear and circular DNA. At high concentration of ABF2p DNA collapses into a tight globular structure. We quantified the compaction of linear DNA by measuring the end-to-end distance of the DNA molecule at increasing concentrations of ABF2p. We also derived a polymer statistical mechanics model that gives quantitative description of compaction observed in our experiments. This model shows that a number of sharp bends in the DNA backbone is often sufficient to cause DNA compaction. Comparison of our model with the experimental data showed excellent quantitative correlation and allowed us to determine binding characteristics for ABF2. Our studies indicate that ABF2 compacts DNA through a novel mechanism that involves bending of DNA backbone. We discuss the implications of such a mechanism for mitochondrial DNA maintenance.

  5. Staying in aerobic shape: how the structural integrity of mitochondria and mitochondrial DNA is maintained.

    PubMed

    Scott, Sidney V; Cassidy-Stone, Ann; Meeusen, Shelly L; Nunnari, Jodi

    2003-08-01

    The structure and integrity of the mitochondrial compartment are features essential for it to function efficiently. The maintenance of mitochondrial structure in cells ranging from yeast to humans has been shown to require both ongoing fission and fusion. Recent characterization of many of the molecular components that direct mitochondrial fission and fusion events have led to a more complete understanding of how these processes take place. Further, mitochondrial fragmentation observed when cells undergo apoptosis requires mitochondrial fission, underlying the importance of mitochondrial dynamics in cellular homeostasis. Mitochondrial structure also impacts mitochondrial DNA inheritance. Recent studies suggest that faithful transmission of mitochondrial DNA to daughter cells might require a mitochondrial membrane tethering apparatus.

  6. Effects of antiviral nucleoside analogs on human DNA polymerases and mitochondrial DNA synthesis.

    PubMed

    Martin, J L; Brown, C E; Matthews-Davis, N; Reardon, J E

    1994-12-01

    Inhibition constants were determined for 16 nucleoside analog triphosphates against human DNA polymerases alpha, beta, gamma, and epsilon, and 7 nucleoside analogs were examined as inhibitors of mitochondrial DNA synthesis in human Molt-4 cells in culture. The results demonstrate no clear quantitative or qualitative correlation between inhibition of DNA polymerases, particularly mitochondrial DNA polymerase gamma, and the inhibition of mitochondrial DNA synthesis in Molt-4 cell culture. Furthermore, the data indicate that inhibition of isolated DNA polymerases may not be predictive of in vitro or in vivo toxicity. Finally, it is not clear whether inhibition of mitochondrial DNA synthesis will be an accurate predictor of the potential in vivo toxicity of antiviral nucleoside analogs.

  7. Phase Transition of DNA Coated Nanogold Networks

    NASA Astrophysics Data System (ADS)

    Kiang, Ching-Hwa; Sun, Young; Harris, Nolan; Wickremasinghe, Nissanka

    2004-03-01

    Melting and hybridization of DNA-coated gold nanoparticle networks are investigated with optical absorption spectroscopy and tansmission electron microscopy. Single-stranded DNA-coated nanogold are linked with complementary, single-stranded linker DNA to form particle networks. Network formation results in a solution color change, which can be used for DNA detection. Compared to free DNA, networked DNA-nanoparticle systems result in a sharp melting transition. Melting curves calculated from percolation theory agree with our experimental results(1). (1) C.-H. Kiang, ``Phase Transition of DNA-Linked Gold Nanoparticles,'' Physica A, 321 (2003) 164--169.

  8. Expression of petite mitochondrial DNA in vivo: zygotic gene rescue.

    PubMed

    Strausberg, R L; Butow, R A

    1977-07-01

    A protocol is introduced for probing the organization and regulation of expression of the yeast mitochondrial genome, termed "zygotic gene rescue." The procedure is based on the notion that genes retained on mitochondrial DNA of on the notion that genes retained on mitochondrial DNA of petites can be expressed in zygotes of a cross between petite and wild type. To test the validity of this notion, we have taken advantage of our ability to discriminate, by mobility differences on sodium dodecyl sulfate/polyacrylamide gels, different forms of the product of alleles of the mitochondrial gene, varI. In petite strains that have retained the varI gene, its characteristic product appears in zygotes 4-5 hr after mating; no product is observed in petite strains deleted in the varI locus. Our studies indicate that (i) expression in the zygote of the varI gene in the petite genome is not exclusively the result of recombination with mitochondrial DNA of the wild-type tester, and (ii) the varI gene is probably reiterated in the petite mitochondrial genome. The strength of the technique of zygotic gene rescue in the analysis of the mitochondrial genome is discussed.

  9. Strong Purifying Selection in Transmission of Mammalian Mitochondrial DNA

    PubMed Central

    Stewart, James Bruce; Freyer, Christoph; Elson, Joanna L; Wredenberg, Anna; Cansu, Zekiye; Trifunovic, Aleksandra; Larsson, Nils-Göran

    2008-01-01

    There is an intense debate concerning whether selection or demographics has been most important in shaping the sequence variation observed in modern human mitochondrial DNA (mtDNA). Purifying selection is thought to be important in shaping mtDNA sequence evolution, but the strength of this selection has been debated, mainly due to the threshold effect of pathogenic mtDNA mutations and an observed excess of new mtDNA mutations in human population data. We experimentally addressed this issue by studying the maternal transmission of random mtDNA mutations in mtDNA mutator mice expressing a proofreading-deficient mitochondrial DNA polymerase. We report a rapid and strong elimination of nonsynonymous changes in protein-coding genes; the hallmark of purifying selection. There are striking similarities between the mutational patterns in our experimental mouse system and human mtDNA polymorphisms. These data show strong purifying selection against mutations within mtDNA protein-coding genes. To our knowledge, our study presents the first direct experimental observations of the fate of random mtDNA mutations in the mammalian germ line and demonstrates the importance of purifying selection in shaping mitochondrial sequence diversity. PMID:18232733

  10. Lack of paternal inheritance of muscle mitochondrial DNA in sporadic mitochondrial myopathies.

    PubMed

    Filosto, Massimiliano; Mancuso, Michelangelo; Vives-Bauza, Cristofol; Vilà, Maya R; Shanske, Sara; Hirano, Michio; Andreu, Antoni L; DiMauro, Salvatore

    2003-10-01

    In 2002, paternal inheritance of muscle mitochondrial DNA (mtDNA) was reported in a patient with exercise intolerance and a mitochondrial DNA (mtDNA) mutation restricted to skeletal muscle. To evaluate whether paternal inheritance is a common phenomenon, we studied 10 sporadic patients with skeletal muscle-restricted mtDNA mutations: five harbored mtDNA point mutations in protein-coding genes and five had single mtDNA deletions. We performed haplotype analysis and direct sequencing of the hypervariable regions 1 and 2 of the D-loop in muscle and blood from the patients and, when available, in blood from their parents. We did not observe paternal inheritance in any of our patients.

  11. Association of mitochondrial antioxidant enzymes with mitochondrial DNA as integral nucleoid constituents

    PubMed Central

    Kienhöfer, Joachim; Häussler, Dagmar Johanna Franziska; Ruckelshausen, Florian; Muessig, Elisabeth; Weber, Klaus; Pimentel, David; Ullrich, Volker; Bürkle, Alexander; Bachschmid, Markus Michael

    2009-01-01

    Mitochondrial DNA (mtDNA) is organized in protein-DNA macrocomplexes called nucleoids. Average nucleoids contain 2–8 mtDNA molecules, which are organized by the histone-like mitochondrial transcription factor A. Besides well-characterized constituents, such as single-stranded binding protein or polymerase γ (Polγ), various other proteins with ill-defined functions have been identified. We report for the first time that mammalian nucleoids contain essential enzymes of an integral antioxidant system. Intact nucleoids were isolated with sucrose density gradients from rat and bovine heart as well as human Jurkat cells. Manganese superoxide dismutase (SOD2) was detected by Western blot in the nucleoid fractions. DNA, mitochondrial glutathione peroxidase (GPx1), and Polγ were coimmunoprecipitated with SOD2 from nucleoid fractions, which suggests that an antioxidant system composed of SOD2 and GPx1 are integral constituents of nucleoids. Interestingly, in cultured bovine endothelial cells the association of SOD2 with mtDNA was absent. Using a sandwich filter-binding assay, direct association of SOD2 by salt-sensitive ionic forces with a chemically synthesized mtDNA fragment was demonstrated. Increasing salt concentrations during nucleoid isolation on sucrose density gradients disrupted the association of SOD2 with mitochondrial nucleoids. Our biochemical data reveal that nucleoids contain an integral antioxidant system that may protect mtDNA from superoxide-induced oxidative damage.—Kienhöfer, J., Häussler, D. J. F., Ruckelshausen, F., Muessig, E., Weber, K., Pimentel, D., Ullrich, V., Bürkle, A., Bachschmid, M. M. Association of mitochondrial antioxidant enzymes with mitochondrial DNA as integral nucleoid constituents. PMID:19228881

  12. Mitochondrial disease in childhood: mtDNA encoded.

    PubMed

    Saneto, Russell P; Sedensky, Margret M

    2013-04-01

    Since the first description of a mitochondrial DNA (mtDNA)-associated disease in the late 1980s, there have been more than 275 mutations within the mtDNA genome described causing human disease. The phenotypic expression of these disorders is vast, as disturbances of the unique physiology of mitochondria can create a wide range of clinical heterogeneity. Features of heteroplasmy, threshold effect, genetic bottleneck, mtDNA depletion, mitotic segregation, and maternal inheritance have been identified and described as a result of novel biochemical and genetic controls of mitochondrial function. We hope that as we unfold this fascinating part of clinical medicine, the reader will see how alterations in the tapestry of mitochondrial biochemistry and genetics can give rise to human illness.

  13. PCR Primers for Metazoan Mitochondrial 12S Ribosomal DNA Sequences

    PubMed Central

    Machida, Ryuji J.; Kweskin, Matthew; Knowlton, Nancy

    2012-01-01

    Background Assessment of the biodiversity of communities of small organisms is most readily done using PCR-based analysis of environmental samples consisting of mixtures of individuals. Known as metagenetics, this approach has transformed understanding of microbial communities and is beginning to be applied to metazoans as well. Unlike microbial studies, where analysis of the 16S ribosomal DNA sequence is standard, the best gene for metazoan metagenetics is less clear. In this study we designed a set of PCR primers for the mitochondrial 12S ribosomal DNA sequence based on 64 complete mitochondrial genomes and then tested their efficacy. Methodology/Principal Findings A total of the 64 complete mitochondrial genome sequences representing all metazoan classes available in GenBank were downloaded using the NCBI Taxonomy Browser. Alignment of sequences was performed for the excised mitochondrial 12S ribosomal DNA sequences, and conserved regions were identified for all 64 mitochondrial genomes. These regions were used to design a primer pair that flanks a more variable region in the gene. Then all of the complete metazoan mitochondrial genomes available in NCBI's Organelle Genome Resources database were used to determine the percentage of taxa that would likely be amplified using these primers. Results suggest that these primers will amplify target sequences for many metazoans. Conclusions/Significance Newly designed 12S ribosomal DNA primers have considerable potential for metazoan metagenetic analysis because of their ability to amplify sequences from many metazoans. PMID:22536450

  14. Multiple mitochondrial DNA deletions in monozygotic twins with OPMD.

    PubMed

    Muqit, M M K; Larner, A J; Sweeney, M G; Sewry, C; Stinton, V J; Davis, M B; Healy, D G; Payne, S J; Chotai, K; Wood, N W; Lane, R J M

    2008-01-01

    Oculopharyngeal muscular dystrophy (OPMD) is caused by expansions of the poly (A) binding protein 2 (PABP2) gene. Previous histological analyses have revealed mitochondrial abnormalities in the muscles of OPMD patients but their significance remains uncertain. We had the rare opportunity to study monozygotic twins with identical expansions of the PABP2 gene but with markedly different severities of OPMD. Both had histological features of mitochondrial myopathy. We determined whether mitochondrial DNA abnormalities underlay these changes. Clinical information was obtained by history and examination. Muscle biopsies were obtained from each subject and genetic analysis was performed using long-range PCR and Southern blotting. We demonstrate, for the first time, the presence of mitochondrial DNA (mtDNA) deletions by Southern blotting in individuals with OPMD. This correlates with the presence of mitochondrial myopathy in both twins. Moreover, both twins had different mtDNA deletions, which might explain their phenotypic differences. We hypothesise that mitochondrial dysfunction may occur as a consequence of PABP2 gene mutations, and that this dysfunction may affect the phenotypic manifestations of OPMD.

  15. Specific mitochondrial DNA deletions in idiopathic dilated cardiomyopathy.

    PubMed

    Marin-Garcia, J; Goldenthal, M J; Ananthakrishnan, R; Pierpont, M E; Fricker, F J; Lipshultz, S E; Perez-Atayde, A

    1996-02-01

    Structural changes in human mitochondrial DNA (mtDNA) have been implicated in a number of clinical conditions with dysfunctions in oxidative phosphorylation called OX-PHOS diseases, some of which have cardiac involvement. The objective of this study was to assess the frequency and extent of specific mitochondrial DNA deletions in idiopathic dilated cardiomyopathy. DNA extracted from tissue derived from the left ventricle of 41 patients with idiopathic dilated cardiomyopathy and 17 controls was amplified by polymerase chain reaction using specific primers to assess the incidence and proportion of 5-kb and 7.4-kb deletions in mitochondrial DNA. In reactions using primers to detect the 5-kb deletion, an amplified product of 593 bp was found in low abundance relative to undeleted mitochondrial DNA but with high frequency in a number of controls and patients. A second deletion of 7.4 kb in size was also frequently present in controls and patients. In contrast to previous reports, these deletions were found to be present in both controls and in cardiomyopathic patients, 18 years and younger, including several infants. The 7.4-kb deletion was prominently increased in both frequency and in its proportion relative to undeleted mitochondrial DNA in patients 40 years and older with idiopathic dilated cardiomyopathy. At variance with current literature our study reports a significant presence of both 5 and 7.4-kb deletions in the young and a higher frequency and quantity of the 7.4-kb deletion in the older cardiomyopathic patients in comparison with controls. The increased accumulation of the 7.4-kb deletion as both a function of aging and cardiomyopathy is suggestive that this specific mitochondrial DNA deletion arises more likely as an effect of heart dysfunction rather than as a primary cause of cardiomyopathy.

  16. Mitochondrial DNA Copy Number in Sleep Duration Discordant Monozygotic Twins.

    PubMed

    Wrede, Joanna E; Mengel-From, Jonas; Buchwald, Dedra; Vitiello, Michael V; Bamshad, Michael; Noonan, Carolyn; Christiansen, Lene; Christensen, Kaare; Watson, Nathaniel F

    2015-10-01

    Mitochondrial DNA (mtDNA) copy number is an important component of mitochondrial function and varies with age, disease, and environmental factors. We aimed to determine whether mtDNA copy number varies with habitual differences in sleep duration within pairs of monozygotic twins. Academic clinical research center. 15 sleep duration discordant monozygotic twin pairs (30 twins, 80% female; mean age 42.1 years [SD 15.0]). Sleep duration was phenotyped with wrist actigraphy. Each twin pair included a "normal" (7-9 h/24) and "short" (< 7 h/24) sleeping twin. Fasting peripheral blood leukocyte DNA was assessed for mtDNA copy number via the n-fold difference between qPCR measured mtDNA and nuclear DNA creating an mtDNA measure without absolute units. We used generalized estimating equation linear regression models accounting for the correlated data structure to assess within-pair effects of sleep duration on mtDNA copy number. Mean within-pair sleep duration difference per 24 hours was 94.3 minutes (SD 62.6 min). We found reduced sleep duration (β = 0.06; 95% CI 0.004, 0.12; P < 0.05) and sleep efficiency (β = 0.51; 95% CI 0.06, 0.95; P < 0.05) were significantly associated with reduced mtDNA copy number within twin pairs. Thus every 1-minute decrease in actigraphy-defined sleep duration was associated with a decrease in mtDNA copy number of 0.06. Likewise, a 1% decrease in actigraphy-defined sleep efficiency was associated with a decrease in mtDNA copy number of 0.51. Reduced sleep duration and sleep efficiency were associated with reduced mitochondrial DNA copy number in sleep duration discordant monozygotic twins offering a potential mechanism whereby short sleep impairs health and longevity through mitochondrial stress. © 2015 Associated Professional Sleep Societies, LLC.

  17. Mitochondrial DNA in Tumor Initiation, Progression, and Metastasis: Role of Horizontal mtDNA Transfer.

    PubMed

    Berridge, Michael V; Dong, Lanfeng; Neuzil, Jiri

    2015-08-15

    Mitochondrial DNA (mtDNA), encoding 13 out of more than 1,000 proteins of the mitochondrial proteome, is of paramount importance for the bioenergetic machinery of oxidative phosphorylation that is required for tumor initiation, propagation, and metastasis. In stark contrast to the widely held view that mitochondria and mtDNA are retained and propagated within somatic cells of higher organisms, recent in vitro and in vivo evidence demonstrates that mitochondria move between mammalian cells. This is particularly evident in cancer where defective mitochondrial respiration can be restored and tumor-forming ability regained by mitochondrial acquisition. This paradigm shift in cancer cell biology and mitochondrial genetics, concerning mitochondrial movement between cells to meet bioenergetic needs, not only adds another layer of plasticity to the armory of cancer cells to correct damaged mitochondria, but also points to potentially new therapeutic approaches.

  18. Mitochondrial retrograde signaling induces epithelial-mesenchymal transition and generates breast cancer stem cells.

    PubMed

    Guha, M; Srinivasan, S; Ruthel, G; Kashina, A K; Carstens, R P; Mendoza, A; Khanna, C; Van Winkle, T; Avadhani, N G

    2014-11-06

    Metastatic breast tumors undergo epithelial-to-mesenchymal transition (EMT), which renders them resistant to therapies targeted to the primary cancers. The mechanistic link between mtDNA (mitochondrial DNA) reduction, often seen in breast cancer patients, and EMT is unknown. We demonstrate that reducing mtDNA content in human mammary epithelial cells (hMECs) activates Calcineurin (Cn)-dependent mitochondrial retrograde signaling pathway, which induces EMT-like reprogramming to fibroblastic morphology, loss of cell polarity, contact inhibition and acquired migratory and invasive phenotype. Notably, mtDNA reduction generates breast cancer stem cells. In addition to retrograde signaling markers, there is an induction of mesenchymal genes but loss of epithelial markers in these cells. The changes are reversed by either restoring the mtDNA content or knockdown of CnAα mRNA, indicating the causal role of retrograde signaling in EMT. Our results point to a new therapeutic strategy for metastatic breast cancers targeted to the mitochondrial retrograde signaling pathway for abrogating EMT and attenuating cancer stem cells, which evade conventional therapies. We report a novel regulatory mechanism by which low mtDNA content generates EMT and cancer stem cells in hMECs.

  19. Mitochondria, mitochondrial DNA and Alzheimer's disease. What comes first?

    PubMed

    Mancuso, M; Orsucci, D; Siciliano, G; Murri, L

    2008-10-01

    To date, the beta amyloid (Abeta) cascade hypothesis remains the main pathogenetic model of Alzheimer's disease (AD), but its role in the majority of sporadic AD cases is unclear. The mitochondria play central role in the bioenergetics of the cell and apoptotic cell death. In the past 20 years research has been directed at clarifying the involvement of mitochondria and defects in mitochondrial oxidative phosphorylation in late-onset neurodegenerative disorders, including AD. Morphological, biochemical and genetic abnormalities of the mitochondria in several AD tissues have been reported. Impaired mitochondrial respiration, particularly COX deficiency, has been observed in brain, platelets and fibroblasts of AD patients. The "mitochondrial cascade hypothesis" could explain many of the biochemical, genetic and pathological features of sporadic AD. Somatic mutations in mitochondrial DNA (mtDNA) could cause energy failure, increased oxidative stress and accumulation of Abeta, which in a vicious cycle reinforces the mtDNA damage and the oxidative stress. Despite the evidence of mitochondrial dysfunction in AD, no causative mutations in the mtDNA have been detected so far. Indeed, results of studies on the role of mtDNA haplogroups in AD are controversial. In this review we discuss the role of the mitochondria in the cascade of events leading to AD, and we will try to provide an answer to the question "what comes first".

  20. Detection of Heteroplasmic Mitochondrial DNA in Single Mitochondria

    PubMed Central

    Reiner, Joseph E.; Kishore, Rani B.; Levin, Barbara C.; Albanetti, Thomas; Boire, Nicholas; Knipe, Ashley; Helmerson, Kristian; Deckman, Koren Holland

    2010-01-01

    Background Mitochondrial DNA (mtDNA) genome mutations can lead to energy and respiratory-related disorders like myoclonic epilepsy with ragged red fiber disease (MERRF), mitochondrial myopathy, encephalopathy, lactic acidosis and stroke (MELAS) syndrome, and Leber's hereditary optic neuropathy (LHON). It is not well understood what effect the distribution of mutated mtDNA throughout the mitochondrial matrix has on the development of mitochondrial-based disorders. Insight into this complex sub-cellular heterogeneity may further our understanding of the development of mitochondria-related diseases. Methodology This work describes a method for isolating individual mitochondria from single cells and performing molecular analysis on that single mitochondrion's DNA. An optical tweezer extracts a single mitochondrion from a lysed human HL-60 cell. Then a micron-sized femtopipette tip captures the mitochondrion for subsequent analysis. Multiple rounds of conventional DNA amplification and standard sequencing methods enable the detection of a heteroplasmic mixture in the mtDNA from a single mitochondrion. Significance Molecular analysis of mtDNA from the individually extracted mitochondrion demonstrates that a heteroplasmy is present in single mitochondria at various ratios consistent with the 50/50 heteroplasmy ratio found in single cells that contain multiple mitochondria. PMID:21179558

  1. Mitochondrial DNA heteroplasmy dynamics in a kindred harboring a novel pathogenic mutation in the mitochondrial tRNA glutamate gene

    SciTech Connect

    Moraes, C.T.; Hao, H.; Bonilla, E.; DiMauro, S.

    1994-09-01

    We have identified a novel mitochondrial DNA (mtDNA) mutation in a 32-year-old male with a myopathy (without progressive external ophthalmoplegia) and mild pyramidal involvement. This A{yields}G transition at mtDNA position 14709 alters an evolutionary conserved nucleotide in a region coding for the anticodon loop of the mitcohondrial tRNA{sup Glu}. The 14709 mtDNA mutation was heteroplasmic but present at very high levels in the patient`s muscle (95%), white blood cells (81%) and hair follicles (90%). The same mutant mtDNA population was observed in white blood cells and hair follicles of all maternal relatives, but a lesser percentage (25-80%). The patient`s muscle showed many ragged-red fibers and a severe focal defect in cytochrome c oxidase activity, accompanied by the absence of cross-reacting material for mitochondrially synthesized polypeptides (ND 1 and COX II). The percentage of mutant mtDNA was not preferentially increased over two generations. Rather, the percentage of mutant mtDNA observed in siblings seemed to follow a normal distribution around the percentage observed in their mothers. Single hair PCR/RFLP analysis showed that the intercellular fluctuation in the percentage of mutant mtDNA differs among family members. Younger generations tend to have a more homogeneous distribution of mutant mtDNA in different hair follicles. The highest degree of variability between individual hair follicles was observed in the patient`s grandmother. These results suggest that the intercellular distribution of the mutant and wild-type mtDNA populations may drift towards homogeneity in subsequent generations.

  2. Silencing of cardiac mitochondrial NHE1 prevents mitochondrial permeability transition pore opening.

    PubMed

    Villa-Abrille, María C; Cingolani, Eugenio; Cingolani, Horacio E; Alvarez, Bernardo V

    2011-04-01

    Inhibition of Na(+)/H(+) exchanger 1 (NHE1) reduces cardiac ischemia-reperfusion (I/R) injury and also cardiac hypertrophy and failure. Although the mechanisms underlying these NHE1-mediated effects suggest delay of mitochondrial permeability transition pore (MPTP) opening, and reduction of mitochondrial-derived superoxide production, the possibility of NHE1 blockade targeting mitochondria has been incompletely explored. A short-hairpin RNA sequence mediating specific knock down of NHE1 expression was incorporated into a lentiviral vector (shRNA-NHE1) and transduced in the rat myocardium. NHE1 expression of mitochondrial lysates revealed that shRNA-NHE1 transductions reduced mitochondrial NHE1 (mNHE1) by ∼60%, supporting the expression of NHE1 in mitochondria membranes. Electron microscopy studies corroborate the presence of NHE1 in heart mitochondria. Immunostaining of rat cardiomyocytes also suggests colocalization of NHE1 with the mitochondrial marker cytochrome c oxidase. To examine the functional role of mNHE1, mitochondrial suspensions were exposed to increasing concentrations of CaCl(2) to induce MPTP opening and consequently mitochondrial swelling. shRNA-NHE1 transduction reduced CaCl(2)-induced mitochondrial swelling by 64 ± 4%. Whereas the NHE1 inhibitor HOE-642 (10 μM) decreased mitochondrial Ca(2+)-induced swelling in rats transduced with nonsilencing RNAi (37 ± 6%), no additional HOE-642 effects were detected in mitochondria from rats transduced with shRNA-NHE1. We have characterized the expression and function of NHE1 in rat heart mitochondria. Because mitochondria from rats injected with shRNA-NHE1 present a high threshold for MPTP formation, the beneficial effects of NHE1 inhibition in I/R resulting from mitochondrial targeting should be considered.

  3. Nuclear gadgets in mitochondrial DNA replication and transcription.

    PubMed

    Clayton, D A

    1991-03-01

    In mammalian mitochondrial DNA, activation of the light-strand promoter mediates both priming of leading-strand replication and initiation of light-strand transcription. Accurate and efficient transcription requires at least two proteins: mitochondrial RNA polymerase and a separable transcription factor that can function across species boundaries. Subsequently, primer RNAs are cleaved by a site-specific ribonucleoprotein endoribonuclease that recognizes short, highly conserved sequence elements in the RNA substrate.

  4. Respiratory chain complex I deficiency caused by mitochondrial DNA mutations

    PubMed Central

    Swalwell, Helen; Kirby, Denise M; Blakely, Emma L; Mitchell, Anna; Salemi, Renato; Sugiana, Canny; Compton, Alison G; Tucker, Elena J; Ke, Bi-Xia; Lamont, Phillipa J; Turnbull, Douglass M; McFarland, Robert; Taylor, Robert W; Thorburn, David R

    2011-01-01

    Defects of the mitochondrial respiratory chain are associated with a diverse spectrum of clinical phenotypes, and may be caused by mutations in either the nuclear or the mitochondrial genome (mitochondrial DNA (mtDNA)). Isolated complex I deficiency is the most common enzyme defect in mitochondrial disorders, particularly in children in whom family history is often consistent with sporadic or autosomal recessive inheritance, implicating a nuclear genetic cause. In contrast, although a number of recurrent, pathogenic mtDNA mutations have been described, historically, these have been perceived as rare causes of paediatric complex I deficiency. We reviewed the clinical and genetic findings in a large cohort of 109 paediatric patients with isolated complex I deficiency from 101 families. Pathogenic mtDNA mutations were found in 29 of 101 probands (29%), 21 in MTND subunit genes and 8 in mtDNA tRNA genes. Nuclear gene defects were inferred in 38 of 101 (38%) probands based on cell hybrid studies, mtDNA sequencing or mutation analysis (nuclear gene mutations were identified in 22 probands). Leigh or Leigh-like disease was the most common clinical presentation in both mtDNA and nuclear genetic defects. The median age at onset was higher in mtDNA patients (12 months) than in patients with a nuclear gene defect (3 months). However, considerable overlap existed, with onset varying from 0 to >60 months in both groups. Our findings confirm that pathogenic mtDNA mutations are a significant cause of complex I deficiency in children. In the absence of parental consanguinity, we recommend whole mitochondrial genome sequencing as a key approach to elucidate the underlying molecular genetic abnormality. PMID:21364701

  5. Mitochondrial DNA deletions and depletion within paraspinal muscles

    PubMed Central

    Campbell, G R; Reeve, A; Ziabreva, I; Polvikoski, T M; Taylor, R W; Reynolds, R; Turnbull, D M; Mahad, D J

    2013-01-01

    Aims Although mitochondrial abnormalities have been reported within paraspinal muscles in patients with axial weakness and neuromuscular disease as well as with ageing, the basis of respiratory deficiency in paraspinal muscles is not known. This study aimed to determine the extent and basis of respiratory deficiency in paraspinal muscles from cases undergoing surgery for degenerative spinal disease and post mortem cases without a history of spinal disease, where age-related histopathological changes were previously reported. Methods Cervical and lumbar paraspinal muscles were obtained peri-operatively from 13 patients and from six post mortem control cases (age range 18–82 years) without a neurological disease. Sequential COX/SDH (mitochondrial respiratory chain complex IV/complex II) histochemistry was performed to identify respiratory-deficient muscle fibres (lacking complex IV with intact complex II activity). Real-time polymerase chain reaction, long-range polymerase chain reaction and sequencing were used to identify and characterize mitochondrial DNA (mtDNA) deletions and determine mtDNA copy number status. Mitochondrial respiratory chain complex subunits were detected by immunohistochemistry. Results The density of respiratory-deficient fibres increased with age. On average, 3.96% of fibres in paraspinal muscles were respiratory-deficient (range 0–10.26). Respiratory deficiency in 36.8% of paraspinal muscle fibres was due to clonally expanded mtDNA deletions. MtDNA depletion accounted for further 13.5% of respiratory deficiency. The profile of immunohistochemically detected subunits of complexes was similar in respiratory-deficient fibres with and without mtDNA deletions or mtDNA depletion. Conclusions Paraspinal muscles appeared to be particularly susceptible to age-related mitochondrial respiratory chain defects. Clonally expanded mtDNA deletions and focal mtDNA depletion may contribute towards the development of age-related postural abnormalities

  6. Ubisol-Q10 Prevents Glutamate-Induced Cell Death by Blocking Mitochondrial Fragmentation and Permeability Transition Pore Opening

    PubMed Central

    Kumari, Santosh; Mehta, Suresh L; Milledge, Gaolin Z.; Huang, Xinyu; Li, Haining; Li, P. Andy

    2016-01-01

    Mitochondrial dysfunction and oxidative stress are the major events that lead to the formation of mitochondrial permeability transition pore (mPTP) during glutamate-induced cytotoxicity and cell death. Coenzyme Q10 (CoQ10) has widely been used for the treatment of mitochondrial disorders and neurodegenerative diseases. Comparing to traditional lipid-soluble CoQ10, water soluble CoQ10 (Ubisol-Q10) has high intracellular and intra-mitochondrial distribution. The aims of the present study are to determine the neuroprotective effects of Ubisol-Q10 on glutamate-induced cell death and to explore its functional mechanisms. HT22 neuronal cells were exposed to glutamate. Cell viability was measured and mitochondrial fragmentation was assessed by mitochondrial imaging. The mPTP opening was determined by mitochondrial membrane potential and calcium retention capacity. The results revealed that the anti-glutamate toxicity effects of Ubisol-Q10 was associated with its ability to block mitochondrial fragmentation, to maintain calcium retention capacity and mitochondrial membrane potential, and to prevent mPTP formation, AIF release, and DNA fragmentation. We concluded that Ubisol-Q10 protects cells from glutamate toxicity by preserving the integrity of mitochondrial structure and function. Therefore, adequate CoQ10 supplementation may be beneficial in preventing cerebral stroke and other disorders that involve mitochondrial dysfunction. PMID:27194946

  7. Mitochondrial DNA disease and developmental implications for reproductive strategies.

    PubMed

    Burgstaller, Joerg Patrick; Johnston, Iain G; Poulton, Joanna

    2015-01-01

    Mitochondrial diseases are potentially severe, incurable diseases resulting from dysfunctional mitochondria. Several important mitochondrial diseases are caused by mutations in mitochondrial DNA (mtDNA), the genetic material contained within mitochondria, which is maternally inherited. Classical and modern therapeutic approaches exist to address the inheritance of mtDNA disease, but are potentially complicated by the fact that cellular mtDNA populations evolve according to poorly-understood dynamics during development and organismal lifetimes. We review these therapeutic approaches and models of mtDNA dynamics during development, and discuss the implications of recent results from these models for modern mtDNA therapies. We particularly highlight mtDNA segregation-differences in proliferative rates between different mtDNA haplotypes-as a potential and underexplored issue in such therapies. However, straightforward strategies exist to combat this and other potential therapeutic problems. In particular, we describe haplotype matching as an approach with the power to potentially ameliorate any expected issues from mtDNA incompatibility.

  8. Mitochondrial DNA disease and developmental implications for reproductive strategies

    PubMed Central

    Burgstaller, Joerg Patrick; Johnston, Iain G.; Poulton, Joanna

    2015-01-01

    Mitochondrial diseases are potentially severe, incurable diseases resulting from dysfunctional mitochondria. Several important mitochondrial diseases are caused by mutations in mitochondrial DNA (mtDNA), the genetic material contained within mitochondria, which is maternally inherited. Classical and modern therapeutic approaches exist to address the inheritance of mtDNA disease, but are potentially complicated by the fact that cellular mtDNA populations evolve according to poorly-understood dynamics during development and organismal lifetimes. We review these therapeutic approaches and models of mtDNA dynamics during development, and discuss the implications of recent results from these models for modern mtDNA therapies. We particularly highlight mtDNA segregation—differences in proliferative rates between different mtDNA haplotypes—as a potential and underexplored issue in such therapies. However, straightforward strategies exist to combat this and other potential therapeutic problems. In particular, we describe haplotype matching as an approach with the power to potentially ameliorate any expected issues from mtDNA incompatibility. PMID:25425607

  9. Induced pluripotent stem cells with a pathological mitochondrial DNA deletion

    PubMed Central

    Cherry, Anne B. C.; Gagne, Katelyn E.; McLoughlin, Erin M.; Baccei, Anna; Gorman, Bryan; Hartung, Odelya; Miller, Justine D.; Zhang, Jin; Zon, Rebecca L.; Ince, Tan A.; Neufeld, Ellis J.; Lerou, Paul H.; Fleming, Mark D.; Daley, George Q.; Agarwal, Suneet

    2013-01-01

    In congenital mitochondrial DNA (mtDNA) disorders, a mixture of normal and mutated mtDNA (termed heteroplasmy) exists at varying levels in different tissues, which determines the severity and phenotypic expression of disease. Pearson marrow pancreas syndrome (PS) is a congenital bone marrow failure disorder caused by heteroplasmic deletions in mtDNA. The cause of the hematopoietic failure in PS is unknown, and adequate cellular and animal models are lacking. Induced pluripotent stem (iPS) cells are particularly amenable for studying mtDNA disorders, as cytoplasmic genetic material is retained during direct reprogramming. Here we derive and characterize iPS cells from a patient with PS. Taking advantage of the tendency for heteroplasmy to change with cell passage, we isolated isogenic PS-iPS cells without detectable levels of deleted mtDNA. We found that PS-iPS cells carrying a high burden of deleted mtDNA displayed differences in growth, mitochondrial function, and hematopoietic phenotype when differentiated in vitro, compared to isogenic iPS cells without deleted mtDNA. Our results demonstrate that reprogramming somatic cells from patients with mtDNA disorders can yield pluripotent stem cells with varying burdens of heteroplasmy that might be useful in the study and treatment of mitochondrial diseases. PMID:23400930

  10. Mitochondrial swinger replication: DNA replication systematically exchanging nucleotides and short 16S ribosomal DNA swinger inserts.

    PubMed

    Seligmann, Hervé

    2014-11-01

    Assuming systematic exchanges between nucleotides (swinger RNAs) resolves genomic 'parenthood' of some orphan mitochondrial transcripts. Twenty-three different systematic nucleotide exchanges (bijective transformations) exist. Similarities between transcription and replication suggest occurrence of swinger DNA. GenBank searches for swinger DNA matching the 23 swinger versions of human and mouse mitogenomes detect only vertebrate mitochondrial swinger DNA for swinger type AT+CG (from five different studies, 149 sequences) matching three human and mouse mitochondrial genes: 12S and 16S ribosomal RNAs, and cytochrome oxidase subunit I. Exchange A<->T+C<->G conserves self-hybridization properties, putatively explaining swinger biases for rDNA, against protein coding genes. Twenty percent of the regular human mitochondrial 16S rDNA consists of short swinger repeats (from 13 exchanges). Swinger repeats could originate from recombinations between regular and swinger DNA: duplicated mitochondrial genes of the parthenogenetic gecko Heteronotia binoei include fewer short A<->T+C<->G swinger repeats than non-duplicated mitochondrial genomes of that species. Presumably, rare recombinations between female and male mitochondrial genes (and in parthenogenetic situations between duplicated genes), favors reverse-mutations of swinger repeat insertions, probably because most inserts affect negatively ribosomal function. Results show that swinger DNA exists, and indicate that swinger polymerization contributes to the genesis of genetic material and polymorphism.

  11. Selective propagation of functional mitochondrial DNA during oogenesis restricts the transmission of a deleterious mitochondrial variant.

    PubMed

    Hill, Jahda H; Chen, Zhe; Xu, Hong

    2014-04-01

    Although mitochondrial DNA (mtDNA) is prone to mutation and few mtDNA repair mechanisms exist, crippling mitochondrial mutations are exceedingly rare. Recent studies have demonstrated strong purifying selection in the mouse female germline. However, the mechanisms underlying positive selection of healthy mitochondria remain to be elucidated. We visualized mtDNA replication during Drosophila melanogaster oogenesis, finding that mtDNA replication commenced before oocyte determination during the late germarium stage and was dependent on mitochondrial fitness. We isolated a temperature-sensitive lethal mtDNA allele, mt:CoI(T300I), which resulted in reduced mtDNA replication in the germarium at the restrictive temperature. Additionally, the frequency of the mt:CoI(T300I) allele in heteroplasmic flies was decreased, both during oogenesis and over multiple generations, at the restrictive temperature. Furthermore, we determined that selection against mt:CoI(T300I) overlaps with the timing of selective replication of mtDNA in the germarium. These findings establish a previously uncharacterized developmental mechanism for the selective amplification of wild-type mtDNA, which may be evolutionarily conserved to limit the transmission of deleterious mutations.

  12. Maternal inheritance and mitochondrial DNA variants in familial Parkinson's disease.

    PubMed

    Simon, David K; Pankratz, Nathan; Kissell, Diane K; Pauciulo, Michael W; Halter, Cheryl A; Rudolph, Alice; Pfeiffer, Ronald F; Nichols, William C; Foroud, Tatiana

    2010-04-01

    Mitochondrial function is impaired in Parkinson's disease (PD) and may contribute to the pathogenesis of PD, but the causes of mitochondrial impairment in PD are unknown. Mitochondrial dysfunction is recapitulated in cell lines expressing mitochondrial DNA (mtDNA) from PD patients, implicating mtDNA variants or mutations, though the role of mtDNA variants or mutations in PD risk remains unclear. We investigated the potential contribution of mtDNA variants or mutations to the risk of PD. We examined the possibility of a maternal inheritance bias as well as the association between mitochondrial haplogroups and maternal inheritance and disease risk in a case-control study of 168 multiplex PD families in which the proband and one parent were diagnosed with PD. 2-tailed Fisher Exact Tests and McNemar's tests were used to compare allele frequencies, and a t-test to compare ages of onset. The frequency of affected mothers of the proband with PD (83/167, 49.4%) was not significantly different from the frequency of affected females of the proband generation (115/259, 44.4%) (Odds Ratio 1.22; 95%CI 0.83-1.81). After correcting for multiple tests, there were no significant differences in the frequencies of mitochondrial haplogroups or of the 10398G complex I gene polymorphism in PD patients compared to controls, and no significant associations with age of onset of PD. Mitochondrial haplogroup and 10398G polymorphism frequencies were similar in probands having an affected father as compared to probands having an affected mother. These data fail to demonstrate a bias towards maternal inheritance in familial PD. Consistent with this, we find no association of common haplogroup-defining mtDNA variants or for the 10398G variant with the risk of PD. However, these data do not exclude a role for mtDNA variants in other populations, and it remains possible that other inherited mitochondrial DNA variants, or somatic mDNA mutations, contribute to the risk of familial PD.

  13. Maternal inheritance and mitochondrial DNA variants in familial Parkinson's disease

    PubMed Central

    2010-01-01

    Background Mitochondrial function is impaired in Parkinson's disease (PD) and may contribute to the pathogenesis of PD, but the causes of mitochondrial impairment in PD are unknown. Mitochondrial dysfunction is recapitulated in cell lines expressing mitochondrial DNA (mtDNA) from PD patients, implicating mtDNA variants or mutations, though the role of mtDNA variants or mutations in PD risk remains unclear. We investigated the potential contribution of mtDNA variants or mutations to the risk of PD. Methods We examined the possibility of a maternal inheritance bias as well as the association between mitochondrial haplogroups and maternal inheritance and disease risk in a case-control study of 168 multiplex PD families in which the proband and one parent were diagnosed with PD. 2-tailed Fisher Exact Tests and McNemar's tests were used to compare allele frequencies, and a t-test to compare ages of onset. Results The frequency of affected mothers of the proband with PD (83/167, 49.4%) was not significantly different from the frequency of affected females of the proband generation (115/259, 44.4%) (Odds Ratio 1.22; 95%CI 0.83 - 1.81). After correcting for multiple tests, there were no significant differences in the frequencies of mitochondrial haplogroups or of the 10398G complex I gene polymorphism in PD patients compared to controls, and no significant associations with age of onset of PD. Mitochondrial haplogroup and 10398G polymorphism frequencies were similar in probands having an affected father as compared to probands having an affected mother. Conclusions These data fail to demonstrate a bias towards maternal inheritance in familial PD. Consistent with this, we find no association of common haplogroup-defining mtDNA variants or for the 10398G variant with the risk of PD. However, these data do not exclude a role for mtDNA variants in other populations, and it remains possible that other inherited mitochondrial DNA variants, or somatic mDNA mutations, contribute

  14. Mitochondrial DNA deletions in Alzheimer’s brains: A review

    PubMed Central

    Phillips, Nicole R.; Simpkins, James W.; Roby, Rhonda K.

    2013-01-01

    Mitochondrial dysfunction and increased oxidative stress have been associated with normal aging and possibly implicated in the etiology of late onset Alzheimer’s disease. DNA deletions, as well as other alterations, can result from oxidative damage to nucleic acids. Many studies in the last two decades have investigated the incidence of mitochondrial DNA deletions in post-mortem brain tissues of late onset Alzheimer’s disease patients as compared to age-matched normal controls. Published studies are not entirely concordant, but their differences might shed light on the heterogeneity of Alzheimer’s disease itself. Our understanding the role that mitochondrial DNA deletions plays in disease progression may provide valuable information that could someday lead to a treatment. PMID:23850329

  15. Replication and preferential inheritance of hypersuppressive petite mitochondrial DNA

    PubMed Central

    MacAlpine, David M.; Kolesar, Jill; Okamoto, Koji; Butow, Ronald A.; Perlman, Philip S.

    2001-01-01

    Wild-type yeast mitochondrial DNA (mtDNA) is inherited biparentally, whereas mtDNA of hypersuppressive petite mutants is inherited uniparentally in crosses to strains with wild-type mtDNA. Genomes of hypersuppressive petites contain a conserved ori sequence that includes a promoter, but it is unclear whether the ori confers a segregation or replication advantage. Fluorescent in situ hybridization analysis of wild-type and petite mtDNAs in crosses reveals no preferential segregation of hypersuppressive petite mtDNA to first zygotic buds. We identify single-stranded DNA circles and RNA-primed DNA replication intermediates in hypersuppressive petite mtDNA that are absent from non-hypersuppressive petites. Mutating the promoter blocks hypersuppressiveness in crosses to wild-type strains and eliminates the distinctive replication intermediates. We propose that promoter-dependent RNA-primed replication accounts for the uniparental inheritance of hypersuppressive petite mtDNA. PMID:11285243

  16. Mitochondrial DNA Stress Primes the Antiviral Innate Immune Response

    PubMed Central

    West, A. Phillip; Khoury-Hanold, William; Staron, Matthew; Tal, Michal C.; Pineda, Cristiana M.; Lang, Sabine M.; Bestwick, Megan; Duguay, Brett A.; Raimundo, Nuno; MacDuff, Donna A.; Kaech, Susan M.; Smiley, James R.; Means, Robert E.; Iwasaki, Akiko; Shadel, Gerald S.

    2014-01-01

    Mitochondrial DNA (mtDNA) is normally present at thousands of copies per cell and is packaged into several hundred higher-order structures termed nucleoids1. The abundant mtDNA-binding protein, transcription factor A mitochondrial (TFAM), regulates nucleoid architecture, abundance, and segregation2. Complete mtDNA depletion profoundly impairs oxidative phosphorylation (OXPHOS), triggering calcium-dependent stress signaling and adaptive metabolic responses3. However, the cellular responses to mtDNA instability, a physiologically relevant stress observed in many human diseases and aging, remain ill-defined4. Here we show that moderate mtDNA stress elicited by TFAM deficiency engages cytosolic antiviral signaling to enhance the expression of a subset of interferon-stimulated genes (ISG). Mechanistically, we have found that aberrant mtDNA packaging promotes escape of mtDNA into the cytosol, where it engages the DNA sensor cGAS and promotes STING-IRF3-dependent signaling to elevate ISG expression, potentiate type I interferon responses, and confer broad viral resistance. Furthermore, we demonstrate that herpesviruses induce mtDNA stress, which potentiates antiviral signaling and type I interferon responses during infection. Our results further demonstrate that mitochondria are central participants in innate immunity, identify mtDNA stress as a cell-intrinsic trigger of antiviral signaling, and suggest that cellular monitoring of mtDNA homeostasis cooperates with canonical virus sensing mechanisms to fully license antiviral innate immunity. PMID:25642965

  17. Genetics Home Reference: RRM2B-related mitochondrial DNA depletion syndrome, encephalomyopathic form with renal ...

    MedlinePlus

    ... is packaged in chromosomes within the cell's nucleus (nuclear DNA), mitochondria also have a small amount of their own DNA ( mitochondrial DNA or mtDNA). Mitochondria are the energy-producing centers in cells, and the DNA in ...

  18. Oxidative stress is not a major contributor to somatic mitochondrial DNA mutations.

    PubMed

    Itsara, Leslie S; Kennedy, Scott R; Fox, Edward J; Yu, Selina; Hewitt, Joshua J; Sanchez-Contreras, Monica; Cardozo-Pelaez, Fernando; Pallanck, Leo J

    2014-02-01

    The accumulation of somatic mitochondrial DNA (mtDNA) mutations is implicated in aging and common diseases of the elderly, including cancer and neurodegenerative disease. However, the mechanisms that influence the frequency of somatic mtDNA mutations are poorly understood. To develop a simple invertebrate model system to address this matter, we used the Random Mutation Capture (RMC) assay to characterize the age-dependent frequency and distribution of mtDNA mutations in the fruit fly Drosophila melanogaster. Because oxidative stress is a major suspect in the age-dependent accumulation of somatic mtDNA mutations, we also used the RMC assay to explore the influence of oxidative stress on the somatic mtDNA mutation frequency. We found that many of the features associated with mtDNA mutations in vertebrates are conserved in Drosophila, including a comparable somatic mtDNA mutation frequency (∼10(-5)), an increased frequency of mtDNA mutations with age, and a prevalence of transition mutations. Only a small fraction of the mtDNA mutations detected in young or old animals were G∶C to T∶A transversions, a signature of oxidative damage, and loss-of-function mutations in the mitochondrial superoxide dismutase, Sod2, had no detectable influence on the somatic mtDNA mutation frequency. Moreover, a loss-of-function mutation in Ogg1, which encodes a DNA repair enzyme that removes oxidatively damaged deoxyguanosine residues (8-hydroxy-2'-deoxyguanosine), did not significantly influence the somatic mtDNA mutation frequency of Sod2 mutants. Together, these findings indicate that oxidative stress is not a major cause of somatic mtDNA mutations. Our data instead suggests that somatic mtDNA mutations arise primarily from errors that occur during mtDNA replication. Further studies using Drosophila should aid in the identification of factors that influence the frequency of somatic mtDNA mutations.

  19. Nonneutral mitochondrial DNA variation in humans and chimpanzees

    SciTech Connect

    Nachman, M.W.; Aquadro, C.F.; Brown, W.M.

    1996-03-01

    We sequenced the NADH dehydrogenase subunit 3 (ND3) gene from a sample of 61 humans, five common chimpanzees, and one gorilla to test whether patterns of mitochondrial DNA (mtDNA) variation are consistent with a neutral model of molecular evolution. Within humans and within chimpanzees, the ratio of replacement to silent nucleotide substitutions was higher than observed in comparisons between species, contrary to neutral expectations. To test the generality of this result, we reanalyzed published human RFLP data from the entire mitochondrial genome. Gains of restriction sites relative to a known human mtDNA sequence were used to infer unambiguous nucleotide substitutions. We also compared the complete mtDNA sequences of three humans. Both the RFLP data and the sequence data reveal a higher ratio of replacement to silent nucleotide substitutions within humans than is seen between species. This pattern is observed at most or all human mitochondrial genes and is inconsistent with a strictly neutral model. These data suggest that many mitochondrial protein polymorphisms are slightly deleterious, consistent with studies of human mitochondrial diseases. 59 refs., 2 figs., 8 tabs.

  20. A comprehensive characterization of rare mitochondrial DNA variants in neuroblastoma

    PubMed Central

    Pignataro, Piero; Lasorsa, Vito Alessandro; Hogarty, Michael D.; Castellano, Aurora; Conte, Massimo; Tonini, Gian Paolo; Iolascon, Achille; Gasparre, Giuseppe; Capasso, Mario

    2016-01-01

    Background Neuroblastoma, a tumor of the developing sympathetic nervous system, is a common childhood neoplasm that is often lethal. Mitochondrial DNA (mtDNA) mutations have been found in most tumors including neuroblastoma. We extracted mtDNA data from a cohort of neuroblastoma samples that had undergone Whole Exome Sequencing (WES) and also used snap-frozen samples in which mtDNA was entirely sequenced by Sanger technology. We next undertook the challenge of determining those mutations that are relevant to, or arisen during tumor development. The bioinformatics pipeline used to extract mitochondrial variants from matched tumor/blood samples was enriched by a set of filters inclusive of heteroplasmic fraction, nucleotide variability, and in silico prediction of pathogenicity. Results Our in silico multistep workflow applied both on WES and Sanger-sequenced neuroblastoma samples, allowed us to identify a limited burden of somatic and germline mitochondrial mutations with a potential pathogenic impact. Conclusions The few singleton germline and somatic mitochondrial mutations emerged, according to our in silico analysis, do not appear to impact on the development of neuroblastoma. Our findings are consistent with the hypothesis that most mitochondrial somatic mutations can be considered as ‘passengers’ and consequently have no discernible effect in this type of cancer. PMID:27351283

  1. A comprehensive characterization of rare mitochondrial DNA variants in neuroblastoma.

    PubMed

    Calabrese, Francesco Maria; Clima, Rosanna; Pignataro, Piero; Lasorsa, Vito Alessandro; Hogarty, Michael D; Castellano, Aurora; Conte, Massimo; Tonini, Gian Paolo; Iolascon, Achille; Gasparre, Giuseppe; Capasso, Mario

    2016-08-02

    Neuroblastoma, a tumor of the developing sympathetic nervous system, is a common childhood neoplasm that is often lethal. Mitochondrial DNA (mtDNA) mutations have been found in most tumors including neuroblastoma. We extracted mtDNA data from a cohort of neuroblastoma samples that had undergone Whole Exome Sequencing (WES) and also used snap-frozen samples in which mtDNA was entirely sequenced by Sanger technology. We next undertook the challenge of determining those mutations that are relevant to, or arisen during tumor development. The bioinformatics pipeline used to extract mitochondrial variants from matched tumor/blood samples was enriched by a set of filters inclusive of heteroplasmic fraction, nucleotide variability, and in silico prediction of pathogenicity. Our in silico multistep workflow applied both on WES and Sanger-sequenced neuroblastoma samples, allowed us to identify a limited burden of somatic and germline mitochondrial mutations with a potential pathogenic impact. The few singleton germline and somatic mitochondrial mutations emerged, according to our in silico analysis, do not appear to impact on the development of neuroblastoma. Our findings are consistent with the hypothesis that most mitochondrial somatic mutations can be considered as 'passengers' and consequently have no discernible effect in this type of cancer.

  2. Blood Cell Mitochondrial DNA Content and Premature Ovarian Aging

    PubMed Central

    Cacciatore, Chiara; Busnelli, Marta; Rossetti, Raffaella; Bonetti, Silvia; Paffoni, Alessio; Mari, Daniela; Ragni, Guido; Persani, Luca; Arosio, M.; Beck-Peccoz, P.; Biondi, M.; Bione, S.; Bruni, V.; Brigante, C.; Cannavo`, S.; Cavallo, L.; Cisternino, M.; Colombo, I.; Corbetta, S.; Crosignani, P.G.; D'Avanzo, M.G.; Dalpra, L.; Danesino, C.; Di Battista, E.; Di Prospero, F.; Donti, E.; Einaudi, S.; Falorni, A.; Foresta, C.; Fusi, F.; Garofalo, N.; Giotti, I.; Lanzi, R.; Larizza, D.; Locatelli, N.; Loli, P.; Madaschi, S.; Maghnie, M.; Maiore, S.; Mantero, F.; Marozzi, A.; Marzotti, S.; Migone, N.; Nappi, R.; Palli, D.; Patricelli, M.G.; Pisani, C.; Prontera, P.; Petraglia, F.; Radetti, G.; Renieri, A.; Ricca, I.; Ripamonti, A.; Rossetti, R.; Russo, G.; Russo, S.; Tonacchera, M.; Toniolo, D.; Torricelli, F.; Vegetti, W.; Villa, N.; Vineis, P.; Wasniewsk, M.; Zuffardi, O.

    2012-01-01

    Primary ovarian insufficiency (POI) is a critical fertility defect characterized by an anticipated and silent impairment of the follicular reserve, but its pathogenesis is largely unexplained. The frequent maternal inheritance of POI together with a remarkable dependence of ovarian folliculogenesis upon mitochondrial biogenesis and bioenergetics suggested the possible involvement of a generalized mitochondrial defect. Here, we verified the existence of a significant correlation between blood and ovarian mitochondrial DNA (mtDNA) content in a group of women undergoing ovarian hyperstimulation (OH), and then aimed to verify whether mtDNA content was significantly altered in the blood cells of POI women. We recruited 101 women with an impaired ovarian reserve: 59 women with premature ovarian failure (POF) and 42 poor responders (PR) to OH. A Taqman copy number assay revealed a significant mtDNA depletion (P<0.001) in both POF and PR women in comparison with 43 women of similar age and intact ovarian reserve, or 53 very old women with a previous physiological menopause. No pathogenic variations in the mitochondrial DNA polymerase γ (POLG) gene were detected in 57 POF or PR women with low blood mtDNA content. In conclusion, blood cell mtDNA depletion is a frequent finding among women with premature ovarian aging, suggesting that a still undetermined but generalized mitochondrial defect may frequently predispose to POI which could then be considered a form of anticipated aging in which the ovarian defect may represent the first manifestation. The determination of mtDNA content in blood may become an useful tool for the POI risk prediction. PMID:22879975

  3. Blood cell mitochondrial DNA content and premature ovarian aging.

    PubMed

    Bonomi, Marco; Somigliana, Edgardo; Cacciatore, Chiara; Busnelli, Marta; Rossetti, Raffaella; Bonetti, Silvia; Paffoni, Alessio; Mari, Daniela; Ragni, Guido; Persani, Luca

    2012-01-01

    Primary ovarian insufficiency (POI) is a critical fertility defect characterized by an anticipated and silent impairment of the follicular reserve, but its pathogenesis is largely unexplained. The frequent maternal inheritance of POI together with a remarkable dependence of ovarian folliculogenesis upon mitochondrial biogenesis and bioenergetics suggested the possible involvement of a generalized mitochondrial defect. Here, we verified the existence of a significant correlation between blood and ovarian mitochondrial DNA (mtDNA) content in a group of women undergoing ovarian hyperstimulation (OH), and then aimed to verify whether mtDNA content was significantly altered in the blood cells of POI women. We recruited 101 women with an impaired ovarian reserve: 59 women with premature ovarian failure (POF) and 42 poor responders (PR) to OH. A Taqman copy number assay revealed a significant mtDNA depletion (P<0.001) in both POF and PR women in comparison with 43 women of similar age and intact ovarian reserve, or 53 very old women with a previous physiological menopause. No pathogenic variations in the mitochondrial DNA polymerase γ (POLG) gene were detected in 57 POF or PR women with low blood mtDNA content. In conclusion, blood cell mtDNA depletion is a frequent finding among women with premature ovarian aging, suggesting that a still undetermined but generalized mitochondrial defect may frequently predispose to POI which could then be considered a form of anticipated aging in which the ovarian defect may represent the first manifestation. The determination of mtDNA content in blood may become an useful tool for the POI risk prediction.

  4. Methods for Efficient Elimination of Mitochondrial DNA from Cultured Cells

    PubMed Central

    Spadafora, Domenico; Kozhukhar, Nataliya; Chouljenko, Vladimir N.; Kousoulas, Konstantin G.; Alexeyev, Mikhail F.

    2016-01-01

    Here, we document that persistent mitochondria DNA (mtDNA) damage due to mitochondrial overexpression of the Y147A mutant uracil-N-glycosylase as well as mitochondrial overexpression of bacterial Exonuclease III or Herpes Simplex Virus protein UL12.5M185 can induce a complete loss of mtDNA (ρ0 phenotype) without compromising the viability of cells cultured in media supplemented with uridine and pyruvate. Furthermore, we use these observations to develop rapid, sequence-independent methods for the elimination of mtDNA, and demonstrate utility of these methods for generating ρ0 cells of human, mouse and rat origin. We also demonstrate that ρ0 cells generated by each of these three methods can serve as recipients of mtDNA in fusions with enucleated cells. PMID:27136098

  5. Very Short Mitochondrial DNA Fragments and Heteroplasmy in Human Plasma

    PubMed Central

    Zhang, Ruoyu; Nakahira, Kiichi; Guo, Xiaoxian; Choi, Augustine M.K.; Gu, Zhenglong

    2016-01-01

    Cell free DNA (cfDNA) has received increasing attention and has been studied in a broad range of clinical conditions. However, few studies have focused on mitochondrial DNA (mtDNA) in the cell free form. We optimized DNA isolation and sequencing library preparation protocols to better retain short DNA fragments from plasma, and applied these optimized methods to plasma samples from patients with sepsis. Our methods can retain substantially shorter DNA, resulting in an average of 11.5 fold increase in short DNA fragments yield (DNA <100bp). We report that cf-mtDNA in plasma is highly enriched in short-size cfDNA (30~60 bp). Motivated by this unique size distribution, we size-selected short cfDNA, which further increased the mtDNA recovery rate by an average of 10.4 fold. We then detected mtDNA heteroplasmy in plasma from 3 patients. In one patient who previously received bone marrow transplantation, different minor allele frequencies were observed between plasma and leukocytes at heteroplasmic sites, consistent with mixed-tissue origin for cfDNA. For the other two patients, the heteroplasmy pattern is also different between plasma and leukocyte. Our study shed new lights into the architecture of the cfDNA, and mtDNA heteroplasmy identified in plasma provides new potential for biomarker discovery. PMID:27811968

  6. Development or disease: duality of the mitochondrial permeability transition pore.

    PubMed

    Pérez, María José; Quintanilla, Rodrigo A

    2017-06-01

    Mitochondria is not only a dynamic organelle that produces ATP, but is also an important contributor to cell functions in both development and cell death processes. These paradoxical functions of mitochondria are partially regulated by the mitochondrial permeability transition pore (mPTP), a high-conductance channel that can induce loss of mitochondrial membrane potential, impairment of cellular calcium homeostasis, oxidative stress, and a decrease in ATP production upon pathological activation. Interestingly, despite their different etiologies, several neurodegenerative diseases and heart ischemic injuries share mitochondrial dysfunction as a common element. Generally, mitochondrial impairment is triggered by calcium deregulation that could lead to mPTP opening and cell death. Several studies have shown that opening of the mPTP not only induces mitochondrial damage and cell death, but is also a physiological mechanism involved in different cellular functions. The mPTP participates in regular calcium-release mechanisms that are required for proper metabolic regulation; it is hypothesized that the transient opening of this structure could be the principal mediator of cardiac and brain development. The mPTP also plays a role in protecting against different brain and cardiac disorders in the elderly population. Therefore, the aim of this work was to discuss different studies that show this controversial characteristic of the mPTP; although mPTP is normally associated with several pathological events, new critical findings suggest its importance in mitochondrial function and cell development. Copyright © 2017 Elsevier Inc. All rights reserved.

  7. Sulforaphane Inhibits Mitochondrial Permeability Transition and Oxidative Stress

    PubMed Central

    Greco, Tiffany; Shafer, Jonathan; Fiskum, Gary

    2012-01-01

    Exposure of mitochondria to oxidative stress and elevated Ca2+ promotes opening of the mitochondrial permeability transition pore (PTP), resulting in membrane depolarization, uncoupling of oxidative phosphorylation, and potentially cell death. This study tested the hypothesis that treatment of rats with sulforaphane (SFP), an activator of the Nrf2 pathway of antioxidant gene expression, increases the resistance of liver mitochondria to redox-regulated PTP opening and elevates mitochondrial levels of antioxidants. Rats were injected with SFP or drug vehicle and liver mitochondria were isolated 40 hr later. Respiring mitochondria actively accumulated added Ca2+, which was then released through PTP opening induced by agents that either cause an oxidized shift in the mitochondrial redox state or that directly oxidize protein thiol groups. SFP treatment of rats inhibited the rate of pro-oxidant-induced mitochondrial Ca2+ release and increased expression of the glutathione peroxidase/reductase system, thioredoxin, and malic enzyme. These results are the first to demonstrate that SFP treatment of animals increases liver mitochondrial antioxidant defenses and inhibits redox-sensitive PTP opening. This novel form of preconditioning could protect against a variety of pathologies that include oxidative stress and mitochondrial dysfunction in their etiologies. PMID:21986339

  8. Alterations of the mitochondrial proteome caused by the absence of mitochondrial DNA: A proteomic view

    PubMed Central

    Chevallet, Mireille; Lescuyer, Pierre; Diemer, Hélène; van Dorsselaer, Alain; Leize-Wagner, Emmanuelle; Rabilloud, Thierry

    2006-01-01

    The proper functioning of mitochondria requires that both the mitochondrial and the nuclear genome are functional. To investigate the importance of the mitochondrial genome, which encodes only 13 subunits of the respiratory complexes, the mitochondrial rRNAs and a few tRNAs, we performed a comparative study on the 143B cell line and on its Rho-0 counterpart, i.e. devoid of mitochondrial DNA. Quantitative differences were found, of course in the respiratory complexes subunits, but also in the mitochondrial translation apparatus, mainly mitochondrial ribosomal proteins, and in the ion and protein import system, i.e. including membrane proteins. Various mitochondrial metabolic processes were also altered, especially electron transfer proteins and some dehydrogenases, but quite often on a few proteins for each pathway. This study also showed variations in some hypothetical or poorly characterized proteins, suggesting a mitochondrial localization for these proteins. Examples include a stomatin-like protein and a protein sharing homologies with bacterial proteins implicated in tyrosine catabolism. Proteins involved in apoptosis control are also found modulated in Rho-0 mitochondria. PMID:16548050

  9. Mitochondrial DNA inheritance in the human fungal pathogen Cryptococcus gattii.

    PubMed

    Wang, Zixuan; Wilson, Amanda; Xu, Jianping

    2015-02-01

    The inheritance of mitochondrial DNA (mtDNA) is predominantly uniparental in most sexual eukaryotes. In this study, we examined the mitochondrial inheritance pattern of Cryptococcus gattii, a basidiomycetous yeast responsible for the recent and ongoing outbreak of cryptococcal infections in the US Pacific Northwest and British Columbia (especially Vancouver Island) in Canada. Using molecular markers, we analyzed the inheritance of mtDNA in 14 crosses between strains within and between divergent lineages in C. gattii. Consistent with results from recent studies, our analyses identified significant variations in mtDNA inheritance patterns among strains and crosses, ranging from strictly uniparental to biparental. For two of the crosses that showed uniparental mitochondrial inheritance in standard laboratory conditions, we further investigated the effects of the following environmental variables on mtDNA inheritance: UV exposure, temperature, and treatments with the methylation inhibitor 5-aza-2'-deoxycytidine and with the ubiquitination inhibitor ammonium chloride. Interestingly, one of these crosses showed no response to these environmental variables while the other exhibited diverse patterns ranging from complete uniparental inheritance of the MATa parent mtDNA, to biparental inheritance, and to a significant bias toward inheritance of the MATα parental mtDNA. Our results indicate that mtDNA inheritance in C. gattii differs from that in its closely related species Cryptococcus neoformans.

  10. Fructose consumption induces hypomethylation of hepatic mitochondrial DNA in rats.

    PubMed

    Yamazaki, Mirai; Munetsuna, Eiji; Yamada, Hiroya; Ando, Yoshitaka; Mizuno, Genki; Murase, Yuri; Kondo, Kanako; Ishikawa, Hiroaki; Teradaira, Ryoji; Suzuki, Koji; Ohashi, Koji

    2016-03-15

    Fructose may play a crucial role in the pathogenesis of metabolic syndrome (MetS). However, the pathogenic mechanism of the fructose-induced MetS has not yet been investigated fully. Recently, several reports have investigated the association between mitochondrial DNA (mtDNA) and MetS. We examined the effect of fructose-rich diets on mtDNA content, transcription, and epigenetic changes. Four-week-old male Sprague-Dawley rats were offered a 20% fructose solution for 14weeks. We quantified mRNAs for hepatic mitochondrial genes and analyzed the mtDNA methylation (5-mC and 5-hmC) levels using ELISA kits. Histological analysis revealed non-alcoholic fatty liver disease (NAFLD) in fructose-fed rats. Hepatic mtDNA content and transcription were higher in fructose-fed rats than in the control group. Global hypomethylation of mtDNA was also observed in fructose-fed rats. We showed that fructose consumption stimulates hepatic mtDNA-encoded gene expression. This phenomenon might be due to epigenetic changes in mtDNA. Fructose-induced mitochondrial epigenetic changes appear to be a novel mechanism underlying the pathology of MetS and NAFLD. Copyright © 2016 Elsevier Inc. All rights reserved.

  11. Mitochondrial DNA repair: a novel therapeutic target for heart failure.

    PubMed

    Marín-García, José

    2016-09-01

    Mitochondria play a crucial role in a variety of cellular processes ranging from energy metabolism, generation of reactive oxygen species (ROS) and Ca(2+) handling to stress responses, cell survival and death. Malfunction of the organelle may contribute to the pathogenesis of neuromuscular, cancer, premature aging and cardiovascular diseases (CVD), including myocardial ischemia, cardiomyopathy and heart failure (HF). Mitochondria contain their own genome organized into DNA-protein complexes, called "mitochondrial nucleoids," along with multiprotein machineries, which promote mitochondrial DNA (mtDNA) replication, transcription and repair. Although the mammalian organelle possesses almost all known nuclear DNA repair pathways, including base excision repair, mismatch repair and recombinational repair, the proximity of mtDNA to the main sites of ROS production and the lack of protective histones may result in increased susceptibility to various types of mtDNA damage. These include accumulation of mtDNA point mutations and/or deletions and decreased mtDNA copy number, which will impair mitochondrial function and finally, may lead to CVD including HF.

  12. Intrinsic mitochondrial DNA repair defects in Ataxia Telangiectasia.

    PubMed

    Sharma, Nilesh K; Lebedeva, Maria; Thomas, Terace; Kovalenko, Olga A; Stumpf, Jeffrey D; Shadel, Gerald S; Santos, Janine H

    2014-01-01

    Ataxia Telangiectasia (A-T) is a progressive childhood disorder characterized most notably by cerebellar degeneration and predisposition to cancer. A-T is caused by mutations in the kinase ATM, a master regulator of the DNA double-strand break response. In addition to DNA-damage signaling defects, A-T cells display mitochondrial dysfunction that is thought to contribute to A-T pathogenesis. However, the molecular mechanism leading to mitochondrial dysfunction in A-T remains unclear. Here, we show that lack of ATM leads to reduced mitochondrial DNA (mtDNA) integrity and mitochondrial dysfunction, which are associated to defective mtDNA repair. While protein levels of mtDNA repair proteins are essentially normal, in the absence of ATM levels specifically of DNA ligase III (Lig3), the only DNA ligase working in mitochondria is reduced. The reduction of Lig3 is observed in different A-T patient cells, in brain and pre-B cells derived from ATM knockout mice as well as upon transient or stable knockdown of ATM. Furthermore, pharmacological inhibition of Lig3 in wild type cells phenocopies the mtDNA repair defects observed in A-T patient cells. As targeted deletion of LIG3 in the central nervous system causes debilitating ataxia in mice, reduced Lig3 protein levels and the consequent mtDNA repair defect may contribute to A-T neurodegeneration. A-T is thus the first disease characterized by diminished Lig3. Published by Elsevier B.V.

  13. Inheritance of mitochondrial DNA in the conifer Larix.

    PubMed

    Deverno, L L; Charest, P J; Bonen, L

    1993-04-01

    Restriction fragment length polymorphisms between Larix leptolepis and Larix decidua were identified in heterologous hybridization experiments, using wheat mitochondrial DNA probes specific for atp9, coxI, nad3/rps12, and orf25. Analysis of eight individuals of each reciprocal hybrid of these two species revealed that mitochondrial DNA was maternally inherited. Furthermore, sequences homologous to wheat orf25 were also identified in Larix gmelini, Larix siberica, Larix olgensis, and Larix laricina, as well as Ginkgo biloba, Picea mariana, Picea glauca and Pinus contorta.

  14. Mitochondrial DNA Mutation Associated with Leber's Hereditary Optic Neuropathy

    NASA Astrophysics Data System (ADS)

    Wallace, Douglas C.; Singh, Gurparkash; Lott, Marie T.; Hodge, Judy A.; Schurr, Theodore G.; Lezza, Angela M. S.; Elsas, Louis J.; Nikoskelainen, Eeva K.

    1988-12-01

    Leber's hereditary optic neuropathy is a maternally inherited disease resulting in optic nerve degeneration and cardiac dysrhythmia. A mitochondrial DNA replacement mutation was identified that correlated with this disease in multiple families. This mutation converted a highly conserved arginine to a histidine at codon 340 in the NADH dehydrogenase subunit 4 gene and eliminated an Sfa NI site, thus providing a simple diagnostic test. This finding demonstrated that a nucleotide change in a mitochondrial DNA energy production gene can result in a neurological disease.

  15. Mitochondrial DNA evidence of southward migration of Manchus in China.

    PubMed

    Zhao, Yong-Bin; Sun, Wen-Yi; Zhan, Yang; Di, Wang; Yu, Chang-Chun

    2011-01-01

    The Northeast area of China is a cross region between East Asia and Siberia. Although five populations from this area have been studied in maternal lineage, little is known about the genetics of other populations. In this study, forty-seven Manchu individuals were analyzed using a mitochondrial DNA marker, and fourteen mitochondrial DNA haplogroups, the representative haplogroups of east Eurasian, were identified. All analyses showed that Manchu were close to the neighboring populations such as Mongolian, Korean and northern Han Chinese, and were far from the other populations who lived in the cradle of Manchu, suggesting that the Manchu integrated gradually with natives following its southward migration.

  16. A novel interaction between DNA ligase III and DNA polymerase gamma plays an essential role in mitochondrial DNA stability.

    PubMed

    De, Ananya; Campbell, Colin

    2007-02-15

    The data in the present study show that DNA polymerase gamma and DNA ligase III interact in mitochondrial protein extracts from cultured HT1080 cells. An interaction was also observed between the two recombinant proteins in vitro. Expression of catalytically inert versions of DNA ligase III that bind DNA polymerase gamma was associated with reduced mitochondrial DNA copy number and integrity. In contrast, overexpression of wild-type DNA ligase III had no effect on mitochondrial DNA copy number or integrity. Experiments revealed that wild-type DNA ligase III facilitates the interaction of DNA polymerase gamma with a nicked DNA substrate in vitro, and that the zinc finger domain of DNA ligase III is required for this activity. Mitochondrial protein extracts prepared from cells overexpressing a DNA ligase III protein that lacked the zinc finger domain had reduced base excision repair activity compared with extracts from cells overexpressing the wild-type protein. These data support the interpretation that the interaction of DNA ligase III and DNA polymerase gamma is required for proper maintenance of the mammalian mitochondrial genome.

  17. More evidence for non-maternal inheritance of mitochondrial DNA?

    PubMed

    Bandelt, H-J; Kong, Q-P; Parson, W; Salas, A

    2005-12-01

    A single case of paternal co-transmission of mitochondrial DNA (mtDNA) in humans has been reported so far. To find potential instances of non-maternal inheritance of mtDNA. Published medical case studies (of single patients) were searched for irregular mtDNA patterns by comparing the given haplotype information for different clones or tissues with the worldwide mtDNA database as known to date-a method that has proved robust and reliable for the detection of flawed mtDNA sequence data. More than 20 studies were found reporting clear cut instances with mtDNAs of different ancestries in single individuals. As examples, cases are reviewed from recent published reports which, at face value, may be taken as evidence for paternal inheritance of mtDNA or recombination. Multiple types (or recombinant types) of quite dissimilar mitochondrial DNA from different parts of the known mtDNA phylogeny are often reported in single individuals. From re-analyses and corrigenda of forensic mtDNA data, it is apparent that the phenomenon of mixed or mosaic mtDNA can be ascribed solely to contamination and sample mix up.

  18. Selective mitochondrial DNA degradation following double-strand breaks.

    PubMed

    Moretton, Amandine; Morel, Frédéric; Macao, Bertil; Lachaume, Philippe; Ishak, Layal; Lefebvre, Mathilde; Garreau-Balandier, Isabelle; Vernet, Patrick; Falkenberg, Maria; Farge, Géraldine

    2017-01-01

    Mitochondrial DNA (mtDNA) can undergo double-strand breaks (DSBs), caused by defective replication, or by various endogenous or exogenous sources, such as reactive oxygen species, chemotherapeutic agents or ionizing radiations. MtDNA encodes for proteins involved in ATP production, and maintenance of genome integrity following DSBs is thus of crucial importance. However, the mechanisms involved in mtDNA maintenance after DSBs remain unknown. In this study, we investigated the consequences of the production of mtDNA DSBs using a human inducible cell system expressing the restriction enzyme PstI targeted to mitochondria. Using this system, we could not find any support for DSB repair of mtDNA. Instead we observed a loss of the damaged mtDNA molecules and a severe decrease in mtDNA content. We demonstrate that none of the known mitochondrial nucleases are involved in the mtDNA degradation and that the DNA loss is not due to autophagy, mitophagy or apoptosis. Our study suggests that a still uncharacterized pathway for the targeted degradation of damaged mtDNA in a mitophagy/autophagy-independent manner is present in mitochondria, and might provide the main mechanism used by the cells to deal with DSBs.

  19. In vitro replication of human mitochondrial DNA: accurate initiation at the origin of light-strand synthesis.

    PubMed

    Wong, T W; Clayton, D A

    1985-10-01

    Synthesis of human light-strand mitochondrial DNA was accomplished in vitro using DNA primase, DNA polymerase, and other accessory proteins isolated from human mitochondria. Replication begins with the synthesis of primer RNA on a T-rich sequence in the origin stem-loop structure of the template DNA and absolutely requires ATP. A transition from RNA synthesis to DNA synthesis occurs near the base of the stem-loop structure and a potential recognition site for signaling that transition has been identified. The start sites of the in vitro products were mapped at the nucleotide level and were found to be in excellent agreement with those of in vivo nascent light-strand DNA. Isolated human mitochondrial enzymes recognize and utilize the bovine, but not the mouse, origin of light-strand replication.

  20. DNA methyltransferase 1 mutations and mitochondrial pathology: is mtDNA methylated?

    PubMed Central

    Maresca, Alessandra; Zaffagnini, Mirko; Caporali, Leonardo; Carelli, Valerio; Zanna, Claudia

    2015-01-01

    Autosomal dominant cerebellar ataxia-deafness and narcolepsy (ADCA-DN) and Hereditary sensory neuropathy with dementia and hearing loss (HSN1E) are two rare, overlapping neurodegenerative syndromes that have been recently linked to allelic dominant pathogenic mutations in the DNMT1 gene, coding for DNA (cytosine-5)-methyltransferase 1 (DNMT1). DNMT1 is the enzyme responsible for maintaining the nuclear genome methylation patterns during the DNA replication and repair, thus regulating gene expression. The mutations responsible for ADCA-DN and HSN1E affect the replication foci targeting sequence domain, which regulates DNMT1 binding to chromatin. DNMT1 dysfunction is anticipated to lead to a global alteration of the DNA methylation pattern with predictable downstream consequences on gene expression. Interestingly, ADCA-DN and HSN1E phenotypes share some clinical features typical of mitochondrial diseases, such as optic atrophy, peripheral neuropathy, and deafness, and some biochemical evidence of mitochondrial dysfunction. The recent discovery of a mitochondrial isoform of DNMT1 and its proposed role in methylating mitochondrial DNA (mtDNA) suggests that DNMT1 mutations may directly affect mtDNA and mitochondrial physiology. On the basis of this latter finding the link between DNMT1 abnormal activity and mitochondrial dysfunction in ADCA-DN and HSN1E appears intuitive, however, mtDNA methylation remains highly debated. In the last years several groups demonstrated the presence of 5-methylcytosine in mtDNA by different approaches, but, on the other end, the opposite evidence that mtDNA is not methylated has also been published. Since over 1500 mitochondrial proteins are encoded by the nuclear genome, the altered methylation of these genes may well have a critical role in leading to the mitochondrial impairment observed in ADCA-DN and HSN1E. Thus, many open questions still remain unanswered, such as why mtDNA should be methylated, and how this process is regulated and

  1. DNA Precursor Metabolism and Mitochondrial Genome Stability

    DTIC Science & Technology

    2003-04-01

    mitochondrial thiamine pyrophosphate depletion, embryonic lethality, CNS malformations, and anemia. Proc. Natl. Acad. Sci. USA 103, 15927–15932. List of papers...to facilitate deoxyribonucleotide transport, with diphosphates being the preferred substrates. Biesecker’s laboratory had generated knockout mice...transport ribonucleotides in reconstituted liposomes, with diphosphates again being the preferred substrates. That led us to speculate that the

  2. Effects of reduced mitochondrial DNA content on secondary mitochondrial toxicant exposure in Caenorhabditis elegans

    PubMed Central

    Luz, Anthony L.

    2016-01-01

    The mitochondrial genome (mtDNA) is intimately linked to cellular and organismal health, as demonstrated by the fact that mutations in and depletion of mtDNA result in severe mitochondrial disease in humans. However, cells contain hundreds to thousands of copies of mtDNA, which provides genetic redundancy, and creates a threshold effect in which a large percentage of mtDNA must be lost prior to clinical pathogenesis. As certain pharmaceuticals and genetic mutations can result in depletion of mtDNA, and as many environmental toxicants target mitochondria, it is important to understand whether reduced mtDNA will sensitize an individual to toxicant exposure. Here, using ethidium bromide (EtBr), which preferentially inhibits mtDNA replication, we reduced mtDNA 35-55% in the in vivo model organism Caenorhabditis elegans. Chronic, lifelong, low-dose EtBr exposure did not disrupt nematode development or lifespan, and induced only mild alterations in mitochondrial respiration, while having no effect on steady-state ATP levels. Next, we exposed nematodes with reduced mtDNA to the known and suspected mitochondrial toxicants aflatoxin B1, arsenite, paraquat, rotenone or ultraviolet C radiation (UVC). EtBr pre-exposure resulted in mild sensitization of nematodes to UVC and arsenite, had no effect on AfB1 and paraquat, and provided some protection from rotenone toxicity. These mixed results provide a first line of evidence suggesting that reduced mtDNA content may sensitize an individual to certain environmental exposures. PMID:27566481

  3. Effects of reduced mitochondrial DNA content on secondary mitochondrial toxicant exposure in Caenorhabditis elegans.

    PubMed

    Luz, Anthony L; Meyer, Joel N

    2016-09-01

    The mitochondrial genome (mtDNA) is intimately linked to cellular and organismal health, as demonstrated by the fact that mutations in and depletion of mtDNA result in severe mitochondrial disease in humans. However, cells contain hundreds to thousands of copies of mtDNA, which provides genetic redundancy, and creates a threshold effect in which a large percentage of mtDNA must be lost prior to clinical pathogenesis. As certain pharmaceuticals and genetic mutations can result in depletion of mtDNA, and as many environmental toxicants target mitochondria, it is important to understand whether reduced mtDNA will sensitize an individual to toxicant exposure. Here, using ethidium bromide (EtBr), which preferentially inhibits mtDNA replication, we reduced mtDNA 35-55% in the in vivo model organism Caenorhabditis elegans. Chronic, lifelong, low-dose EtBr exposure did not disrupt nematode development or lifespan, and induced only mild alterations in mitochondrial respiration, while having no effect on steady-state ATP levels. Next, we exposed nematodes with reduced mtDNA to the known and suspected mitochondrial toxicants aflatoxin B1, arsenite, paraquat, rotenone or ultraviolet C radiation (UVC). EtBr pre-exposure resulted in mild sensitization of nematodes to UVC and arsenite, had no effect on AfB1 and paraquat, and provided some protection from rotenone toxicity. These mixed results provide a first line of evidence suggesting that reduced mtDNA content may sensitize an individual to certain environmental exposures. Copyright © 2016 Elsevier B.V. and Mitochondria Research Society. All rights reserved.

  4. Mitochondrial Dysfunction Due to Oxidative Mitochondrial DNA Damage Is Reduced through Cooperative Actions of Diverse Proteins

    PubMed Central

    O'Rourke, Thomas W.; Doudican, Nicole A.; Mackereth, Melinda D.; Doetsch, Paul W.; Shadel, Gerald S.

    2002-01-01

    The mitochondrial genome is a significant target of exogenous and endogenous genotoxic agents; however, the determinants that govern this susceptibility and the pathways available to resist mitochondrial DNA (mtDNA) damage are not well characterized. Here we report that oxidative mtDNA damage is elevated in strains lacking Ntg1p, providing the first direct functional evidence that this mitochondrion-localized, base excision repair enzyme functions to protect mtDNA. However, ntg1 null strains did not exhibit a mitochondrial respiration-deficient (petite) phenotype, suggesting that mtDNA damage is negotiated by the cooperative actions of multiple damage resistance pathways. Null mutations in ABF2 or PIF1, two genes implicated in mtDNA maintenance and recombination, exhibit a synthetic-petite phenotype in combination with ntg1 null mutations that is accompanied by enhanced mtDNA point mutagenesis in the corresponding double-mutant strains. This phenotype was partially rescued by malonic acid, indicating that reactive oxygen species generated by the electron transport chain contribute to mitochondrial dysfunction in abf2Δ strains. In contrast, when two other genes involved in mtDNA recombination, CCE1 and NUC1, were inactivated a strong synthetic-petite phenotype was not observed, suggesting that the effects mediated by Abf2p and Pif1p are due to novel activities of these proteins other than recombination. These results document the existence of recombination-independent mechanisms in addition to base excision repair to cope with oxidative mtDNA damage in Saccharomyces cerevisiae. Such systems are likely relevant to those operating in human cells where mtDNA recombination is less prevalent, validating yeast as a model system in which to study these important issues. PMID:12024022

  5. Rapid Discrimination of Mitochondrial DNA Type and Use of Results to Study Mitochondrial Inheritance in Pleurotus spp.

    PubMed

    Sagawa, I; Moriyama, Y; Yanagi, S O; Ando, A; Nagata, Y

    1998-01-01

    We have reported a simple and rapid method to discriminate species in the genus Pleurotus by analysis of restriction-fragment-length polymorphism of whole-cell DNA, and found that several restriction enzymes gave DNA bands useful in such discrimination, but other enzymes tested did not. In the present study, we report the reason why there were useful and useless enzymes; the effective enzymes digested rDNA into small fragments that did not interfere with the detection of DNA bands useful for discrimination. The origin of these discriminative DNA bands was found to be mitochondrial DNA when the banding profiles of whole-cell DNA, mitochondrial DNA, and nuclear DNA were compared. Consequently, our method could be used for rapid and simple identification of mitochondrial DNA type in the genus Pleurotus. The results were used to study mitochondrial inheritance, and we found that only the nucleus but not the mitochondria migrated during the mating of Pleurotus cornucopiae with P. citrinopileatus.

  6. Establishment of a heteroplasmic mouse strain with interspecific mitochondrial DNA haplotypes and improvement of a PCR-RFLP-based measurement system for estimation of mitochondrial DNA heteroplasmy.

    PubMed

    Shitara, Hiroshi; Cao, Liqin; Yamaguchi, Midori; Yonekawa, Hiromichi; Taya, Choji

    2017-02-20

    Mitochondrial DNA segregation is one of the characteristic modes of mitochondrial inheritance in which the heteroplasmic state of mitochondrial DNA is transmitted to the next generation in variable proportions. To analyze mitochondrial DNA segregation, we produced a heteroplasmic mouse strain with interspecific mitochondrial DNA haplotypes, which contains two types of mitochondrial DNA derived from C57BL/6J and Mus spretus strains. The strain was produced on a C57BL/6J nuclear genomic background by microinjection of donor cytoplasm into fertilized eggs. The PCR-RFLP semi-quantitative analysis method, which was improved to reduce the effect of heteroduplex formation, was used to measure the proportion of heteroplasmic mitochondrial DNA in tissues. Founder mice contained up to approximately 14% of exogenous Mus spretus mitochondrial DNA molecules in their tails, and the detected proportions differed among tissues of the same individual. Heteroplasmic mitochondrial DNA is transmitted to the next generation in varying proportions under the maternal inheritance mode. This mitochondrial heteroplasmic mouse strain and the improved PCR-RFLP measurement system enable analysis of the transmission of heteroplasmic mitochondrial DNA variants between tissues and generations.

  7. Mitochondrial DNA Copy Number in Sleep Duration Discordant Monozygotic Twins

    PubMed Central

    Wrede, Joanna E.; Mengel-From, Jonas; Buchwald, Dedra; Vitiello, Michael V.; Bamshad, Michael; Noonan, Carolyn; Christiansen, Lene; Christensen, Kaare; Watson, Nathaniel F.

    2015-01-01

    Study Objectives: Mitochondrial DNA (mtDNA) copy number is an important component of mitochondrial function and varies with age, disease, and environmental factors. We aimed to determine whether mtDNA copy number varies with habitual differences in sleep duration within pairs of monozygotic twins. Setting: Academic clinical research center. Participants: 15 sleep duration discordant monozygotic twin pairs (30 twins, 80% female; mean age 42.1 years [SD 15.0]). Design: Sleep duration was phenotyped with wrist actigraphy. Each twin pair included a “normal” (7–9 h/24) and “short” (< 7 h/24) sleeping twin. Fasting peripheral blood leukocyte DNA was assessed for mtDNA copy number via the n-fold difference between qPCR measured mtDNA and nuclear DNA creating an mtDNA measure without absolute units. We used generalized estimating equation linear regression models accounting for the correlated data structure to assess within-pair effects of sleep duration on mtDNA copy number. Measurements and Results: Mean within-pair sleep duration difference per 24 hours was 94.3 minutes (SD 62.6 min). We found reduced sleep duration (β = 0.06; 95% CI 0.004, 0.12; P < 0.05) and sleep efficiency (β = 0.51; 95% CI 0.06, 0.95; P < 0.05) were significantly associated with reduced mtDNA copy number within twin pairs. Thus every 1-minute decrease in actigraphy-defined sleep duration was associated with a decrease in mtDNA copy number of 0.06. Likewise, a 1% decrease in actigraphy-defined sleep efficiency was associated with a decrease in mtDNA copy number of 0.51. Conclusions: Reduced sleep duration and sleep efficiency were associated with reduced mitochondrial DNA copy number in sleep duration discordant monozygotic twins offering a potential mechanism whereby short sleep impairs health and longevity through mitochondrial stress. Citation: Wrede JE, Mengel-From J, Buchwald D, Vitiello MV, Bamshad M, Noonan C, Christiansen L, Christensen K, Watson NF. Mitochondrial DNA copy number

  8. Mitochondrial DNA deletions in patients with chronic suppurative otitis media.

    PubMed

    Tatar, Arzu; Tasdemir, Sener; Sahin, Ibrahim; Bozoglu, Ceyda; Erdem, Haktan Bagis; Yoruk, Ozgur; Tatar, Abdulgani

    2016-09-01

    The aim of this study was to investigate the 4977 and 7400 bp deletions of mitochondrial DNA in patients with chronic suppurative otitis media and to indicate the possible association of mitochondrial DNA deletions with chronic suppurative otitis media. Thirty-six patients with chronic suppurative otitis media were randomly selected to assess the mitochondrial DNA deletions. Tympanomastoidectomy was applied for the treatment of chronic suppurative otitis media, and the curettage materials including middle ear tissues were collected. The 4977 and 7400 bp deletion regions and two control regions of mitochondrial DNA were assessed by using the four pair primers. DNA was extracted from middle ear tissues and peripheral blood samples of the patients, and then polymerase chain reactions (PCRs) were performed. PCR products were separated in 2 % agarose gel. Seventeen of 36 patients had the heterozygote 4977 bp deletion in the middle ear tissue but not in peripheral blood. There wasn't any patient who had the 7400 bp deletion in mtDNA of their middle ear tissue or peripheral blood tissue. The patients with the 4977 bp deletion had a longer duration of chronic suppurative otitis media and a higher level of hearing loss than the others (p < 0.01). Long time chronic suppurative otitis media and the reactive oxygen species can cause the mitochondrial DNA deletions and this may be a predisposing factor to sensorineural hearing loss in chronic suppurative otitis media. An antioxidant drug as a scavenger agent may be used in long-term chronic suppurative otitis media.

  9. Rapamycin drives selection against a pathogenic heteroplasmic mitochondrial DNA mutation.

    PubMed

    Dai, Ying; Zheng, Kangni; Clark, Joanne; Swerdlow, Russell H; Pulst, Stefan M; Sutton, James P; Shinobu, Leslie A; Simon, David K

    2014-02-01

    Mitochondrial DNA (mtDNA) mutations cause a variety of mitochondrial disorders for which effective treatments are lacking. Emerging data indicate that selective mitochondrial degradation through autophagy (mitophagy) plays a critical role in mitochondrial quality control. Inhibition of mammalian target of rapamycin (mTOR) kinase activity can activate mitophagy. To test the hypothesis that enhancing mitophagy would drive selection against dysfunctional mitochondria harboring higher levels of mutations, thereby decreasing mutation levels over time, we examined the impact of rapamycin on mutation levels in a human cytoplasmic hybrid (cybrid) cell line expressing a heteroplasmic mtDNA G11778A mutation, the most common cause of Leber's hereditary optic neuropathy. Inhibition of mTORC1/S6 kinase signaling by rapamycin induced colocalization of mitochondria with autophagosomes, and resulted in a striking progressive decrease in levels of the G11778A mutation and partial restoration of ATP levels. Rapamycin-induced upregulation of mitophagy was confirmed by electron microscopic evidence of increased autophagic vacuoles containing mitochondria-like organelles. The decreased mutational burden was not due to rapamycin-induced cell death or mtDNA depletion, as there was no significant difference in cytotoxicity/apoptosis or mtDNA copy number between rapamycin and vehicle-treated cells. These data demonstrate the potential for pharmacological inhibition of mTOR kinase activity to activate mitophagy as a strategy to drive selection against a heteroplasmic mtDNA G11778A mutation and raise the exciting possibility that rapamycin may have therapeutic potential for the treatment of mitochondrial disorders associated with heteroplasmic mtDNA mutations, although further studies are needed to determine if a similar strategy will be effective for other mutations and other cell types.

  10. Fecal source tracking in water using a mitochondrial DNA microarray.

    PubMed

    Vuong, Nguyet-Minh; Villemur, Richard; Payment, Pierre; Brousseau, Roland; Topp, Edward; Masson, Luke

    2013-01-01

    A mitochondrial-based microarray (mitoArray) was developed for rapid identification of the presence of 28 animals and one family (cervidae) potentially implicated in fecal pollution in mixed activity watersheds. Oligonucleotide probes for genus or subfamily-level identification were targeted within the 12S rRNA - Val tRNA - 16S rRNA region in the mitochondrial genome. This region, called MI-50, was selected based on three criteria: 1) the ability to be amplified by universal primers 2) these universal primer sequences are present in most commercial and domestic animals of interest in source tracking, and 3) that sufficient sequence variation exists within this region to meet the minimal requirements for microarray probe discrimination. To quantify the overall level of mitochondrial DNA (mtDNA) in samples, a quantitative-PCR (Q-PCR) universal primer pair was also developed. Probe validation was performed using DNA extracted from animal tissues and, for many cases, animal-specific fecal samples. To reduce the amplification of potentially interfering fish mtDNA sequences during the MI-50 enrichment step, a clamping PCR method was designed using a fish-specific peptide nucleic acid. DNA extracted from 19 water samples were subjected to both array and independent PCR analyses. Our results confirm that the mitochondrial microarray approach method could accurately detect the dominant animals present in water samples emphasizing the potential for this methodology in the parallel scanning of a large variety of animals normally monitored in fecal source tracking.

  11. Maternally transmitted mitochondrial DNA mutations can reduce lifespan

    PubMed Central

    Ross, Jaime M.; Coppotelli, Giuseppe; Hoffer, Barry J.; Olson, Lars

    2014-01-01

    We recently showed that germline transmission of mitochondrial DNA mutations via the oocyte cause aggravation of aging phenotypes in prematurely aging mtDNA mutator (PolgAmut/mut) mice. We discovered that 32% of these mice also exhibit stochastic disturbances of brain development, when maternal mtDNA mutations were combined with homozygosity for the PolgA mutation, leading to de novo somatic mtDNA mutations. Surprisingly, we also found that maternally transmitted mtDNA mutations can cause mild premature aging phenotypes also in mice with a wild-type nuclear DNA background. We now report that in addition to the early onset of aging phenotypes, these mice, burdened only by low levels of mtDNA mutations transmitted via the germline, also exhibit reduced longevity. Our data thus demonstrate that low levels of maternally inherited mtDNA mutations when present during development can affect both overall health and lifespan negatively. PMID:25299268

  12. [An efficient method for isolation of mitochondrial DNA in wheat].

    PubMed

    Li, Wen-Qiang; Zhang, Gai-Sheng; Wang, Kui; Niu, Na; Pan, Dong-Liang

    2007-06-01

    An efficient method for isolation of mitochondrial DNA (mtDNA) from etiolated tissues of wheat was developed. The protocol consists of mitochondria isolation with differential centrifugation, Dnase I treatment, lysis with SDS and proteinase K, removing protein by TE-saturated phenol/chloroform extraction and a final RNase A treatment for obtaining mtDNA. The mtDNA samples were tested using spectrophotometry and agarose gel electrophoresis. It was proved that the mtDNA isolated by this method not only have the high yield but also structural complete, and contains no impurities, such as nuclear DNA, RNA and protein. The result showed that this high quality mtDNA can be successfully used in PCR and other genetic studies. In addition, it was found that adjusting the lysis temperature has a noticeable effect on the mtDNA yield.

  13. Mitochondrial DNA mutations in ageing and disease: implications for HIV?

    PubMed

    Payne, Brendan A I; Gardner, Kristian; Chinnery, Patrick F

    2015-01-01

    Mitochondrial DNA (mtDNA) mutations cause neurological and multisystem disease. Somatic (acquired) mtDNA mutations are also associated with degenerative diseases and with normal human ageing. It is well established that certain nucleoside reverse transcriptase inhibitor (NRTI) antiretroviral drugs cause inhibition of the mtDNA polymerase, pol γ, leading to a reduction in mtDNA content (depletion). Given this effect of NRTI therapy on mtDNA replication, it is plausible that NRTI treatment may also lead to increased mtDNA mutations. Here we review recent evidence for an effect of HIV infection or NRTI therapy on mtDNA mutations, as well as discussing the methodological challenges in addressing this question. Finally, we discuss the possible implications for HIV-infected persons, with particular reference to ageing.

  14. Mitochondrial DNA replication during differentiation of murine embryonic stem cells.

    PubMed

    Facucho-Oliveira, Joao M; Alderson, Jon; Spikings, Emma C; Egginton, Stuart; St John, Justin C

    2007-11-15

    Oxidative phosphorylation (OXPHOS), the intracellular process that generates the majority of the ATP of a cell through the electron-transfer chain, is highly dependent on proteins encoded by the mitochondrial genome (mtDNA). MtDNA replication is regulated by the nuclear-encoded mitochondrial transcription factor A (TFAM) and the mitochondrial-specific DNA polymerase gamma, which consists of a catalytic (POLG) and an accessory (POLG2) subunit. Differentiation of pluripotent embryonic stem cells (ESCs) into specific cell types requires expansion of discrete populations of mitochondria and mtDNA replication to meet the specific metabolic requirements of the cell. We determined by real-time PCR that expression of pluripotent markers is reduced before the upregulation of Polg, Polg2 and Tfam in spontaneously differentiating R1 murine (m)ESCs, along with transient increases in mtDNA copy number. In D3 mESCs, the initial transient increase did not take place. However, precursors of neuronal and cardiomyocyte differentiation were positive for both POLG and TFAM. Similar-stage ESCs also showed active mtDNA replication, identified by 5-bromo-2'-deoxy-uridine labelling, as mtDNA copy number increased. Retinoic-acid-induced differentiation resulted in more consistent patterns of replication and upregulation of Polg, Polg2 and Tfam, whereas siRNA knockdown demonstrated that steady-state expression of POLG is essential for maintaining pluripotency.

  15. Indirubin-3'-oxime impairs mitochondrial oxidative phosphorylation and prevents mitochondrial permeability transition induction

    SciTech Connect

    Varela, Ana T.; Gomes, Ana P.; Simoes, Anabela M.; Teodoro, Joao S.; Duarte, Filipe V.; Rolo, Anabela P.; Palmeira, Carlos M.

    2008-12-01

    Indirubin, a red colored 3,2'-bisindole isomer, is a component of Indigo naturalis and is an active ingredient used in traditional Chinese medicine for the treatment of chronic diseases. The family of indirubin derivatives, such as indirubin-3'-oxime, has been suggested for various therapeutic indications. However, potential toxic interactions such as indirubin effects on mitochondrial bioenergetics are still unknown. This study evaluated the action of indirubin-3'-oxime on the function of isolated rat liver mitochondria contributing to a better understanding of the biochemical mechanisms underlying the multiple effects of indirubin. Indirubin-3'-oxime incubated with isolated rat liver mitochondria, at concentrations above 10{mu}M, significantly depresses the phosphorylation efficiency of mitochondria as inferred from the decrease in the respiratory control and ADP/O ratios, the perturbations in mitochondrial membrane potential and in the phosphorylative cycle induced by ADP. Furthermore, indirubin-3'-oxime at up to 25{mu}M stimulates the rate of state 4 respiration and inhibits state 3 respiration. The increased lag phase of repolarization was associated with a direct inhibition of the mitochondrial ATPase. Indirubin-3'-oxime significantly inhibited the activity of complex II and IV thus explaining the decreased FCCP-stimulated mitochondrial respiration. Mitochondria pre-incubated with indirubin-3'-oxime exhibits decreased susceptibility to calcium-induced mitochondrial permeability transition. This work shows for the first time multiple effects of indirubin-3'-oxime on mitochondrial bioenergetics thus indicating a potential mechanism for indirubin-3'-oxime effects on cell function.

  16. Mitochondrial DNA damage by bleomycin induces AML cell death.

    PubMed

    Yeung, ManTek; Hurren, Rose; Nemr, Carine; Wang, Xiaoming; Hershenfeld, Samantha; Gronda, Marcela; Liyanage, Sanduni; Wu, Yan; Augustine, Jeevan; Lee, Eric A; Spagnuolo, Paul A; Southall, Noel; Chen, Catherine; Zheng, Wei; Jeyaraju, Danny V; Minden, Mark D; Laposa, Rebecca; Schimmer, Aaron D

    2015-06-01

    Mitochondria contain multiple copies of their own 16.6 kb circular genome. To explore the impact of mitochondrial DNA (mtDNA) damage on mitochondrial (mt) function and viability of AML cells, we screened a panel of DNA damaging chemotherapeutic agents to identify drugs that could damage mtDNA. We identified bleomycin as an agent that damaged mtDNA in AML cells at concentrations that induced cell death. Bleomycin also induced mtDNA damage in primary AML samples. Consistent with the observed mtDNA damage, bleomycin reduced mt mass and basal oxygen consumption in AML cells. We also demonstrated that the observed mtDNA damage was functionally important for bleomycin-induced cell death. Finally, bleomycin delayed tumor growth in xenograft mouse models of AML and anti-leukemic concentrations of the drug induced mtDNA damage in AML cells preferentially over normal lung tissue. Taken together, mtDNA-targeted therapy may be an effective strategy to target AML cells and bleomycin could be useful in the treatment of this disease.

  17. Evidence for Recombination of Mitochondrial DNA in Triploid Crucian Carp

    PubMed Central

    Guo, Xinhong; Liu, Shaojun; Liu, Yun

    2006-01-01

    In this study, we report the complete mitochondrial DNA (mtDNA) sequences of the allotetraploid and triploid crucian carp and compare the complete mtDNA sequences between the triploid crucian carp and its female parent Japanese crucian carp and between the triploid crucian carp and its male parent allotetraploid. Our results indicate that the complete mtDNA nucleotide identity (98%) between the triploid crucian carp and its male parent allotetraploid was higher than that (93%) between the triploid crucian carp and its female parent Japanese crucian carp. Moreover, the presence of a pattern of identity and difference at synonymous sites of mitochondrial genomes between the triploid crucian carp and its parents provides direct evidence that triploid crucian carp possessed the recombination mtDNA fragment (12,759 bp) derived from the paternal fish. These results suggest that mtDNA recombination was derived from the fusion of the maternal and paternal mtDNAs. Compared with the haploid egg with one set of genome from the Japanese crucian carp, the diploid sperm with two sets of genomes from the allotetraploid could more easily make its mtDNA fuse with the mtDNA of the haploid egg. In addition, the triple hybrid nature of the triploid crucian carp probably allowed its better mtDNA recombination. In summary, our results provide the first evidence of mtDNA combination in polyploid fish. PMID:16322508

  18. Nuclear and mitochondrial DNA quantification of various forensic materials.

    PubMed

    Andréasson, H; Nilsson, M; Budowle, B; Lundberg, H; Allen, M

    2006-12-01

    Due to the different types and quality of forensic evidence materials, their DNA content can vary substantially, and particularly low quantities can impact the results in an identification analysis. In this study, the quantity of mitochondrial and nuclear DNA was determined in a variety of materials using a previously described real-time PCR method. DNA quantification in the roots and distal sections of plucked and shed head hairs revealed large variations in DNA content particularly between the root and the shaft of plucked hairs. Also large intra- and inter-individual variations were found among hairs. In addition, DNA content was estimated in samples collected from fingerprints and accessories. The quantification of DNA on various items also displayed large variations, with some materials containing large amounts of nuclear DNA while no detectable nuclear DNA and only limited amounts of mitochondrial DNA were seen in others. Using this sensitive real-time PCR quantification assay, a better understanding was obtained regarding DNA content and variation in commonly analysed forensic evidence materials and this may guide the forensic scientist as to the best molecular biology approach for analysing various forensic evidence materials.

  19. Direct quantification of mitochondria and mitochondrial DNA dynamics.

    PubMed

    Nomura, Yasutomo

    2012-11-01

    Mitochondria are known to be one of major organelles within a cell and to play a crucial role in many cellular functions. These organelles show the dynamic behaviors such as fusion, fission and the movement along cytoskeletal tracks. Besides mitochondria, mitochondrial DNA is also highly motile. Molecular analysis revealed that several proteins are involved in mitochondria and mitochondrial DNA dynamics. In addition to the degeneration of specific nerves with high energy requirement, mutation of genes coding these proteins results in metabolic diseases. During the last few years, a significant amount of relevant data has been obtained on molecular basis of these diseases but mitochondrial dynamics in cells derived from the patients is poorly understood. So far time-lapse fluorescence microscopy, fluorescence recovery after photo bleaching and image correlation methods have been used to study organellar motion. Especially, image correlation method has possibility to evaluate diffusion coefficient of mitochondria and mitochondrial DNA simultaneously and directly. When we search candidates for compounds that modulate mitochondrial dynamics by high throughput screening, image correlation method may be useful although the careful interpretation is required for crowded and heterogeneous environment within a cell.

  20. Absence of pathogenic mitochondrial DNA mutations in mouse brain tumors

    PubMed Central

    Kiebish, Michael A; Seyfried, Thomas N

    2005-01-01

    Background Somatic mutations in the mitochondrial genome occur in numerous tumor types including brain tumors. These mutations are generally found in the hypervariable regions I and II of the displacement loop and unlikely alter mitochondrial function. Two hypervariable regions of mononucleotide repeats occur in the mouse mitochondrial genome, i.e., the origin of replication of the light strand (OL) and the Arg tRNA. Methods In this study we examined the entire mitochondrial genome in a series of chemically induced brain tumors in the C57BL/6J strain and spontaneous brain tumors in the VM mouse strain. The tumor mtDNA was compared to that of mtDNA in brain mitochondrial populations from the corresponding syngeneic mouse host strain. Results Direct sequencing revealed a few homoplasmic base pair insertions, deletions, and substitutions in the tumor cells mainly in regions of mononucleotide repeats. A heteroplasmic mutation in the 16srRNA gene was detected in a spontaneous metastatic VM brain tumor. Conclusion None of the mutations were considered pathogenic, indicating that mtDNA somatic mutations do not likely contribute to the initiation or progression of these diverse mouse brain tumors. PMID:16105171

  1. Mitochondrial Aging: Focus on Mitochondrial DNA Damage in Atherosclerosis - A Mini-Review.

    PubMed

    Sobenin, Igor A; Zhelankin, Andrey V; Sinyov, Vasily V; Bobryshev, Yuri V; Orekhov, Alexander N

    2015-01-01

    Atherosclerosis is a complex disease which can be described as an excessive fibrofatty, proliferative, inflammatory response to damage to the artery wall involving several cell types such as smooth muscle cells, monocyte-derived macrophages, lymphocytes, dendritic cells and platelets. On the other hand, atherosclerosis is a typical age-related degenerative pathology, which is characterized by signs of cell senescence in the arterial wall including reduced cell proliferation, irreversible growth arrest and apoptosis, increased DNA damage, the presence of epigenetic modifications, shortening of telomere length and mitochondrial dysfunction. The most prominent characteristics of mitochondrial aging are their structural alterations and mitochondrial DNA damage. The mechanisms of mitochondrial genome damage in the development of chronic age-related diseases such as atherosclerosis are not yet well understood. This review focuses on the latest findings from studies of those mutations of the mitochondrial genome which may play an important role in the development of atherosclerosis and which are, at the same time, also markers of mitochondrial aging and cell senescence. © 2014 S. Karger AG, Basel.

  2. Reduction of nuclear encoded enzymes of mitochondrial energy metabolism in cells devoid of mitochondrial DNA

    SciTech Connect

    Mueller, Edith E.; Mayr, Johannes A.; Zimmermann, Franz A.; Feichtinger, Rene G.; Stanger, Olaf; Sperl, Wolfgang; Kofler, Barbara

    2012-01-20

    Highlights: Black-Right-Pointing-Pointer We examined OXPHOS and citrate synthase enzyme activities in HEK293 cells devoid of mtDNA. Black-Right-Pointing-Pointer Enzymes partially encoded by mtDNA show reduced activities. Black-Right-Pointing-Pointer Also the entirely nuclear encoded complex II and citrate synthase exhibit reduced activities. Black-Right-Pointing-Pointer Loss of mtDNA induces a feedback mechanism that downregulates complex II and citrate synthase. -- Abstract: Mitochondrial DNA (mtDNA) depletion syndromes are generally associated with reduced activities of oxidative phosphorylation (OXPHOS) enzymes that contain subunits encoded by mtDNA. Conversely, entirely nuclear encoded mitochondrial enzymes in these syndromes, such as the tricarboxylic acid cycle enzyme citrate synthase (CS) and OXPHOS complex II, usually exhibit normal or compensatory enhanced activities. Here we report that a human cell line devoid of mtDNA (HEK293 {rho}{sup 0} cells) has diminished activities of both complex II and CS. This finding indicates the existence of a feedback mechanism in {rho}{sup 0} cells that downregulates the expression of entirely nuclear encoded components of mitochondrial energy metabolism.

  3. Opening of the mitochondrial permeability transition pore links mitochondrial dysfunction to insulin resistance in skeletal muscle☆

    PubMed Central

    Taddeo, E.P.; Laker, R.C.; Breen, D.S.; Akhtar, Y.N.; Kenwood, B.M.; Liao, J.A.; Zhang, M.; Fazakerley, D.J.; Tomsig, J.L.; Harris, T.E.; Keller, S.R.; Chow, J.D.; Lynch, K.R.; Chokki, M.; Molkentin, J.D.; Turner, N.; James, D.E.; Yan, Z.; Hoehn, K.L.

    2013-01-01

    Insulin resistance is associated with mitochondrial dysfunction, but the mechanism by which mitochondria inhibit insulin-stimulated glucose uptake into the cytoplasm is unclear. The mitochondrial permeability transition pore (mPTP) is a protein complex that facilitates the exchange of molecules between the mitochondrial matrix and cytoplasm, and opening of the mPTP occurs in response to physiological stressors that are associated with insulin resistance. In this study, we investigated whether mPTP opening provides a link between mitochondrial dysfunction and insulin resistance by inhibiting the mPTP gatekeeper protein cyclophilin D (CypD) in vivo and in vitro. Mice lacking CypD were protected from high fat diet-induced glucose intolerance due to increased glucose uptake in skeletal muscle. The mitochondria in CypD knockout muscle were resistant to diet-induced swelling and had improved calcium retention capacity compared to controls; however, no changes were observed in muscle oxidative damage, insulin signaling, lipotoxic lipid accumulation or mitochondrial bioenergetics. In vitro, we tested 4 models of insulin resistance that are linked to mitochondrial dysfunction in cultured skeletal muscle cells including antimycin A, C2-ceramide, ferutinin, and palmitate. In all models, we observed that pharmacological inhibition of mPTP opening with the CypD inhibitor cyclosporin A was sufficient to prevent insulin resistance at the level of insulin-stimulated GLUT4 translocation to the plasma membrane. The protective effects of mPTP inhibition on insulin sensitivity were associated with improved mitochondrial calcium retention capacity but did not involve changes in insulin signaling both in vitro and in vivo. In sum, these data place the mPTP at a critical intersection between alterations in mitochondrial function and insulin resistance in skeletal muscle. PMID:24634818

  4. Heterogeneous base distribution in mitochondrial DNA of Neurospora crassa.

    PubMed Central

    Terpstra, P; Holtrop, M; Kroon, A

    1977-01-01

    The mitochondrial DNA of Neurospora crassa has a heterogeneous intramolecular base distribution. A contiguous piece, representing at least 30% of the total genome, has a G+C content that is 6% lower than the overall G+C content of the DNA. The genes for both ribosomal RNAs are contained in the remaining, relatively G+C rich, part of the genome. PMID:141040

  5. Mitochondrial DNA insertions in the nuclear horse genome.

    PubMed

    Nergadze, S G; Lupotto, M; Pellanda, P; Santagostino, M; Vitelli, V; Giulotto, E

    2010-12-01

    The insertion of mitochondrial DNA in the nuclear genome generates numts, nuclear sequences of mitochondrial origin. In the horse reference genome, we identified 82 numts and showed that the entire horse mitochondrial DNA is represented as numts without gross bias. Numts were inserted in the horse nuclear genome at random sites and were probably generated during the repair of DNA double-strand breaks. We then analysed 12 numt loci in 20 unrelated horses and found that null alleles, lacking the mitochondrial DNA insertion, were present at six of these loci. At some loci, the null allele is prevalent in the sample analysed, suggesting that, in the horse population, the number of numt loci may be higher than 82 present in the reference genome. Contrary to humans, the insertion polymorphism of numts is extremely frequent in the horse population, supporting the hypothesis that the genome of this species is in a rapidly evolving state. © 2010 The Authors, Journal compilation © 2010 Stichting International Foundation for Animal Genetics.

  6. Fly Diversity Revealed by PCR-RFLP of Mitochondrial DNA

    ERIC Educational Resources Information Center

    Asraoui, Jimmy F.; Sayar, Nancy P.; Knio, Khouzama M.; Smith, Colin A.

    2008-01-01

    In this article, we describe an inexpensive, two-session undergraduate laboratory activity that introduces important molecular biology methods in the context of biodiversity. In the first session, students bring tentatively identified flies (order Diptera, true flies) to the laboratory, extract DNA, and amplify a region of the mitochondrial gene…

  7. Mitochondrial DNA insertions in the nuclear Capra hircus genome.

    PubMed

    Ning, F Y; Fu, J; Du, Z H

    2017-01-23

    Nuclear mitochondrial pseudogenes (numts), originating from mtDNA insertions into the nuclear genome, have been detected in many species. However, the distribution of numts in the newly published nuclear genome of domestic goat (Capra hircus) has not yet been explored. We used the entire goat mtDNA sequence and nuclear genome, to identify 118 numts using BLAST. Of these, 79 were able to map sequences to the genome. Further analysis showed that the size of the numts ranged from 318 to 9608 bp, and the homologous identity between numts and their respective corresponding mtDNA fragments varied between 65 and 99%. The identified Yunnan black goat numts covered nearly all the mitochondrial genes including mtDNA control region, and were distributed over all chromosomes with the exception of chromosomes 18, 21, and 25. The Y chromosome was excluded from our analysis, as sequence data are currently not available. Among the discovered 79 numts that we were able to map to the genome, 26 relatively complete mitochondrial genes were detected. Our results constitute valuable information for subsequent studies related to mitochondrial genes and goat evolution.

  8. Fly Diversity Revealed by PCR-RFLP of Mitochondrial DNA

    ERIC Educational Resources Information Center

    Asraoui, Jimmy F.; Sayar, Nancy P.; Knio, Khouzama M.; Smith, Colin A.

    2008-01-01

    In this article, we describe an inexpensive, two-session undergraduate laboratory activity that introduces important molecular biology methods in the context of biodiversity. In the first session, students bring tentatively identified flies (order Diptera, true flies) to the laboratory, extract DNA, and amplify a region of the mitochondrial gene…

  9. A Polymorphism in Mitochondrial DNA Associated with IQ?

    ERIC Educational Resources Information Center

    Skuder, Patricia; And Others

    1995-01-01

    Of 100 DNA markers examined in an allelic association study, only 1 showed a replicated association with IQ in samples totaling 107 children. How the gene marked by the particular restriction fragment length polymorphism was tracked and its mitochondrial origin identified is described. (SLD)

  10. Y Chromosome, Mitochondrial DNA and Childhood Behavioural Traits.

    PubMed

    Howe, Laurence J; Erzurumluoglu, A Mesut; Davey Smith, George; Rodriguez, Santiago; Stergiakouli, Evie

    2017-09-14

    Many psychiatric traits are sexually dimorphic in terms of prevalence, age of onset, progression and prognosis; sex chromosomes could play a role in these differences. In this study we evaluated the association between Y chromosome and mitochondrial DNA haplogroups with sexually-dimorphic behavioural and psychiatric traits. The study sample included 4,211 males and 4,009 females with mitochondrial DNA haplogroups and 4,788 males with Y chromosome haplogroups who are part of the Avon Longitudinal Study of Parents and Children (ALSPAC) based in the United Kingdom. Different subsets of these populations were assessed using measures of behavioural and psychiatric traits with logistic regression being used to measure the association between haplogroups and the traits. The majority of behavioural traits in our cohort differed between males and females; however Y chromosome and mitochondrial DNA haplogroups were not associated with any of the variables. These findings suggest that if there is common variation on the Y chromosome and mitochondrial DNA associated with behavioural and psychiatric trait variation, it has a small effect.

  11. A Polymorphism in Mitochondrial DNA Associated with IQ?

    ERIC Educational Resources Information Center

    Skuder, Patricia; And Others

    1995-01-01

    Of 100 DNA markers examined in an allelic association study, only 1 showed a replicated association with IQ in samples totaling 107 children. How the gene marked by the particular restriction fragment length polymorphism was tracked and its mitochondrial origin identified is described. (SLD)

  12. Regulation and pharmacology of the mitochondrial permeability transition pore

    PubMed Central

    Zorov, Dmitry B.; Juhaszova, Magdalena; Yaniv, Yael; Nuss, H. Bradley; Wang, Su; Sollott, Steven J.

    2009-01-01

    The ‘mitochondrial permeability transition', characterized by a sudden induced change of the inner mitochondrial membrane permeability for water as well as for small substances (≤1.5 kDa), has been known for three decades. Research interest in the entity responsible for this phenomenon, the ‘mitochondrial permeability transition pore’ (mPTP), has dramatically increased after demonstration that it plays a key role in the life and death decision in cells. Therefore, a better understanding of this phenomenon and its regulation by environmental stresses, kinase signalling, and pharmacological intervention is vital. The characterization of the molecular identity of the mPTP will allow identification of possible pharmacological targets and assist in drug design for its precise regulation. However, despite extensive research efforts, at this point the pore-forming core component(s) of the mPTP remain unidentified. Pivotal new genetic evidence has shown that components once believed to be core elements of the mPTP (namely mitochondrial adenine nucleotide translocator and cyclophilin D) are instead only mPTP regulators (or in the case of voltage-dependent anion channels, probably entirely dispensable). This review provides an update on the current state of knowledge regarding the regulation of the mPTP. PMID:19447775

  13. The mitochondrial permeability transition pore: a mystery solved?

    PubMed Central

    Bernardi, Paolo

    2013-01-01

    The permeability transition (PT) denotes an increase of the mitochondrial inner membrane permeability to solutes with molecular masses up to about 1500 Da. It is presumed to be mediated by opening of a channel, the permeability transition pore (PTP), whose molecular nature remains a mystery. Here I briefly review the history of the PTP, discuss existing models, and present our new results indicating that reconstituted dimers of the FOF1 ATP synthase form a channel with properties identical to those of the mitochondrial megachannel (MMC), the electrophysiological equivalent of the PTP. Open questions remain, but there is now promise that the PTP can be studied by genetic methods to solve the large number of outstanding problems. PMID:23675351

  14. The mitochondrial transcription termination factor mTERF modulates replication pausing in human mitochondrial DNA

    PubMed Central

    Hyvärinen, Anne K.; Pohjoismäki, Jaakko L. O.; Reyes, Aurelio; Wanrooij, Sjoerd; Yasukawa, Takehiro; Karhunen, Pekka J.; Spelbrink, Johannes N.; Holt, Ian J.; Jacobs, Howard T.

    2007-01-01

    The mammalian mitochondrial transcription termination factor mTERF binds with high affinity to a site within the tRNALeu(UUR) gene and regulates the amount of read through transcription from the ribosomal DNA into the remaining genes of the major coding strand of mitochondrial DNA (mtDNA). Electrophoretic mobility shift assays (EMSA) and SELEX, using mitochondrial protein extracts from cells induced to overexpress mTERF, revealed novel, weaker mTERF-binding sites, clustered in several regions of mtDNA, notably in the major non-coding region (NCR). Such binding in vivo was supported by mtDNA immunoprecipitation. Two-dimensional neutral agarose gel electrophoresis (2DNAGE) and 5′ end mapping by ligation-mediated PCR (LM-PCR) identified the region of the canonical mTERF-binding site as a replication pause site. The strength of pausing was modulated by the expression level of mTERF. mTERF overexpression also affected replication pausing in other regions of the genome in which mTERF binding was found. These results indicate a role for TERF in mtDNA replication, in addition to its role in transcription. We suggest that mTERF could provide a system for coordinating the passage of replication and transcription complexes, analogous with replication pause-region binding proteins in other systems, whose main role is to safeguard the integrity of the genome whilst facilitating its efficient expression. PMID:17884915

  15. Seventeen New Complete mtDNA Sequences Reveal Extensive Mitochondrial Genome Evolution within the Demospongiae

    PubMed Central

    Wang, Xiujuan; Lavrov, Dennis V.

    2008-01-01

    Two major transitions in animal evolution–the origins of multicellularity and bilaterality–correlate with major changes in mitochondrial DNA (mtDNA) organization. Demosponges, the largest class in the phylum Porifera, underwent only the first of these transitions and their mitochondrial genomes display a peculiar combination of ancestral and animal-specific features. To get an insight into the evolution of mitochondrial genomes within the Demospongiae, we determined 17 new mtDNA sequences from this group and analyzing them with five previously published sequences. Our analysis revealed that all demosponge mtDNAs are 16- to 25-kbp circular molecules, containing 13–15 protein genes, 2 rRNA genes, and 2–27 tRNA genes. All but four pairs of sampled genomes had unique gene orders, with the number of shared gene boundaries ranging from 1 to 41. Although most demosponge species displayed low rates of mitochondrial sequence evolution, a significant acceleration in evolutionary rates occurred in the G1 group (orders Dendroceratida, Dictyoceratida, and Verticillitida). Large variation in mtDNA organization was also observed within the G0 group (order Homosclerophorida) including gene rearrangements, loss of tRNA genes, and the presence of two introns in Plakortis angulospiculatus. While introns are rare in modern-day demosponge mtDNA, we inferred that at least one intron was present in cox1 of the common ancestor of all demosponges. Our study uncovered an extensive mitochondrial genomic diversity within the Demospongiae. Although all sampled mitochondrial genomes retained some ancestral features, including a minimally modified genetic code, conserved structures of tRNA genes, and presence of multiple non-coding regions, they vary considerably in their size, gene content, gene order, and the rates of sequence evolution. Some of the changes in demosponge mtDNA, such as the loss of tRNA genes and the appearance of hairpin-containing repetitive elements, occurred in

  16. Amphetamines promote mitochondrial dysfunction and DNA damage in pulmonary hypertension

    PubMed Central

    Chen, Pin-I; Cao, Aiqin; Miyagawa, Kazuya; Tojais, Nancy F.; Hennigs, Jan K.; Li, Caiyun G.; Sweeney, Nathaly M.; Inglis, Audrey S.; Wang, Lingli; Li, Dan; Ye, Matthew; Feldman, Brian J.

    2017-01-01

    Amphetamine (AMPH) or methamphetamine (METH) abuse can cause oxidative damage and is a risk factor for diseases including pulmonary arterial hypertension (PAH). Pulmonary artery endothelial cells (PAECs) from AMPH-associated-PAH patients show DNA damage as judged by γH2AX foci and DNA comet tails. We therefore hypothesized that AMPH induces DNA damage and vascular pathology by interfering with normal adaptation to an environmental perturbation causing oxidative stress. Consistent with this, we found that AMPH alone does not cause DNA damage in normoxic PAECs, but greatly amplifies DNA damage in hypoxic PAECs. The mechanism involves AMPH activation of protein phosphatase 2A, which potentiates inhibition of Akt. This increases sirtuin 1, causing deacetylation and degradation of HIF1α, thereby impairing its transcriptional activity, resulting in a reduction in pyruvate dehydrogenase kinase 1 and impaired cytochrome c oxidase 4 isoform switch. Mitochondrial oxidative phosphorylation is inappropriately enhanced and, as a result of impaired electron transport and mitochondrial ROS increase, caspase-3 is activated and DNA damage is induced. In mice given binge doses of METH followed by hypoxia, HIF1α is suppressed and pulmonary artery DNA damage foci are associated with worse pulmonary vascular remodeling. Thus, chronic AMPH/METH can induce DNA damage associated with vascular disease by subverting the adaptive responses to oxidative stress. PMID:28138562

  17. A comprehensive characterization of mitochondrial DNA mutations in glioblastoma multiforme.

    PubMed

    Vidone, Michele; Clima, Rosanna; Santorsola, Mariangela; Calabrese, Claudia; Girolimetti, Giulia; Kurelac, Ivana; Amato, Laura Benedetta; Iommarini, Luisa; Trevisan, Elisa; Leone, Marco; Soffietti, Riccardo; Morra, Isabella; Faccani, Giuliano; Attimonelli, Marcella; Porcelli, Anna Maria; Gasparre, Giuseppe

    2015-06-01

    Glioblastoma multiforme (GBM) is the most malignant brain cancer in adults, with a poor prognosis, whose molecular stratification still represents a challenge in pathology and clinics. On the other hand, mitochondrial DNA (mtDNA) mutations have been found in most tumors as modifiers of the bioenergetics state, albeit in GBM a characterization of the mtDNA status is lacking to date. Here, a characterization of the burden of mtDNA mutations in GBM samples was performed. First, investigation of tumor-specific vs. non tumor-specific mutations was carried out with the MToolBox bioinformatics pipeline by analyzing 45 matched tumor/blood samples, from whole genome or whole exome sequencing datasets obtained from The Cancer Genome Atlas (TCGA) consortium. Additionally, the entire mtDNA sequence was obtained in a dataset of 104 fresh-frozen GBM samples. Mitochondrial mutations with potential pathogenic interest were prioritized based on heteroplasmic fraction, nucleotide variability, and in silico prediction of pathogenicity. A preliminary biochemical analysis of the activity of mitochondrial respiratory complexes was also performed on fresh-frozen GBM samples. Although a high number of mutations was detected, we report that the large majority of them does not pass the prioritization filters. Therefore, a relatively limited burden of pathogenic mutations is indeed carried by GBM, which did not appear to determine a general impairment of the respiratory chain. This article is part of a Directed Issue entitled: Energy Metabolism Disorders and Therapies. Copyright © 2015 Elsevier Ltd. All rights reserved.

  18. Identifying individuals by sequencing mitochondrial DNA from teeth.

    PubMed

    Ginther, C; Issel-Tarver, L; King, M C

    1992-10-01

    Mitochondrial DNA (mtDNA) was extracted from teeth stored from 3 months to 20 years, including teeth from the semi-skeletonized remains of a murder victim which had been buried for 10 months. Tooth donors and/or their maternal relatives provided blood or buccal cells, from which mtDNA was also extracted. Enzymatic amplification and direct sequencing of roughly 650 nucleotides from two highly polymorphic regions of mtDNA yielded identical sequences for each comparison of tooth and fresh DNA. Our results suggest that teeth provide an excellent source for high molecular weight mtDNA that can be valuable for extending the time in which decomposed human remains can be genetically identified.

  19. Characterization of Bombyx mori mitochondrial transcription factor A, a conserved regulator of mitochondrial DNA.

    PubMed

    Sumitani, Megumi; Kondo, Mari; Kasashima, Katsumi; Endo, Hitoshi; Nakamura, Kaoru; Misawa, Toshihiko; Tanaka, Hiromitsu; Sezutsu, Hideki

    2017-04-15

    In the present study, we initially cloned and characterized a mitochondrial transcription factor A (Tfam) homologue in the silkworm, Bombyx mori. Bombyx mori TFAM (BmTFAM) localized to mitochondria in cultured silkworm and human cells, and co-localized with mtDNA nucleoids in human HeLa cells. In an immunoprecipitation analysis, BmTFAM was found to associate with human mtDNA in mitochondria, indicating its feature as a non-specific DNA-binding protein. In spite of the low identity between BmTFAM and human TFAM (26.5%), the expression of BmTFAM rescued mtDNA copy number reductions and enlarged mtDNA nucleoids in HeLa cells, which were induced by human Tfam knockdown. Thus, BmTFAM compensates for the function of human TFAM in HeLa cells, demonstrating that the mitochondrial function of TFAM is highly conserved between silkworms and humans. BmTfam mRNA was strongly expressed in early embryos. Through double-stranded RNA (dsRNA)-based RNA interference (RNAi) in silkworm embryos, we found that the knockdown of BmTFAM reduced the amount of mtDNA and induced growth retardation at the larval stage. Collectively, these results demonstrate that BmTFAM is a highly conserved mtDNA regulator and may be a good candidate for investigating and modulating mtDNA metabolism in this model organism. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Preferential recombination between GC clusters in yeast mitochondrial DNA.

    PubMed Central

    Dieckmann, C L; Gandy, B

    1987-01-01

    Yeast mitochondrial DNA molecules have long, AT-rich intergenic spacers punctuated by short GC clusters. GC-rich elements have previously been characterized by others as preferred sites for intramolecular recombination leading to the formation of subgenomic petite molecules. In the present study we show that GC clusters are favored sites for intermolecular recombination between a petite and the wild-type grande genome. The petite studied retains 6.5 kb of mitochondrial DNA reiterated tandemly to form molecules consisting of repeated units. Genetic selection for integration of tandem 6.5 kb repeats of the petite into the grande genome yielded a novel recombination event. One of two crossovers in a double exchange event occurred as expected in the 6.5 kb of matching sequence between the genomes, whereas the second exchange involved a 44 bp GC cluster in the petite and another 44 bp GC cluster in the grande genome 700 bp proximal to the region of homology. Creation of a mitochondrial DNA molecule with a repetitive region led to secondary recombination events that generated a family of molecules with zero to several petite units. The finding that 44 bp GC clusters are preferred as sites for intermolecular exchange adds to the data on petite excision implicating these elements as recombinational hotspots in the yeast mitochondrial genome. Images Fig. 3. Fig. 4. Fig. 5. PMID:3327690

  1. Characterization of mitochondrial DNA from the pika (Ochotona rufescens rufescens).

    PubMed

    Lesca, C; Moisand, A; Puget, A

    1976-01-01

    Further to anatomical and physiological studies performed on the pika (Ochotona rufescens rufescens), a new laboratory animal, the main characteristics of the mitochondrial DNA from its liver are defined. The buoyant density of this DNA is 1.695 g/cm3, its length 5.30 mum,, i.e., 3.17 times that of the replicative form of phiX 174. It could have approximately 16 500 base pairs. The DNA from the pika is very similar to that of the rat or the rabbit, although these animals show great physiological differences.

  2. Lamivudine/telbivudine-associated neuromyopathy: neurogenic damage, mitochondrial dysfunction and mitochondrial DNA depletion

    PubMed Central

    Xu, Hongliang; Wang, Zhaoxia; Zheng, Lemin; Zhang, Wei; Lv, He; Jin, Suqin; Yuan, Yun

    2014-01-01

    Aims Myopathy or neuropathy has been associated with lamivudine/telbivudine therapy in hepatitis B patients. We aim to describe the pathological changes of lamivudine/telbivudine-associated neuromyopathy. Methods We retrospectively recruited six patients who were diagnosed with nucleotide analogues-associated myopathy or neuropathy. Muscle and nerve biopsy were performed, and the specimens were prepared for the light microscopy and electron microscopy. Genomic DNA was extracted from frozen muscle specimens, and the mitochondrial DNA (mtDNA) content was quantified by real-time PCR. Results Recovery of the myopathy can be achieved after the discontinuation or changing the drugs to entecavir. Muscle and nerve biopsy revealed similar changes under either the light or electronic microscopy in all the subjects. Quantitative real-time PCR revealed decrease of mtDNA content in the affected muscle. Conclusions MtDNA depletion results in mitochondrial dysfunction in the lamivudine/telbivudine-associated neuromyopathy. Myopathy was characterised by mitochondrial dysfunction accompanied with neurogenic damage due to axonal neuropathy. Ultrastructure changes of mitochondria included vacuolisation, simplification of the cristae and homogenised matrix. PMID:25190818

  3. Mitochondrial encephalomyopathies: a correlation between neuropathological findings and defects in mitochondrial DNA.

    PubMed

    McKelvie, P A; Morley, J B; Byrne, E; Marzuki, S

    1991-03-01

    Neuropathological studies were carried out in two patients with mitochondrial encephalomyopathies in whom the underlying lesions in muscle mitochondrial DNA (mtDNA) and respiratory enzyme complexes have been investigated. The first, a man with Kearns-Sayre syndrome, died at the age of 49 years. Autopsy showed an old parietal lobe infarct, diffuse spongiform leukoencephalopathy of cerebral and cerebellar white matter and mild spongiform change in deep grey matter and brainstem nuclei. Heteroplasmy of skeletal muscle mitochondrial DNA with a 3.5 kb mtDNA deletion in one of two mtDNA populations was found. The second case, a woman, suffering from myoclonic epilepsy, cerebellar ataxia, bilateral sensorineural deafness, several 'stroke-like' episodes died at age 52. At autopsy, an old infarct was seen in the L internal capsule. Severe loss of neurons and gliosis were found in the dentate nuclei, moderate changes in the red nuclei and inferior olivary nuclei and mild changes in the substantial nigra and locus coeruleus. In both patients, skeletal muscle biopsy showed numbers of ragged-red fibres and intramitochondrial paracrystalline inclusions at electron microscopy. A defect in the synthesis of the ND5 subunit of the respiratory complex I was suggested in the second patient in whom a diagnosis of MELAS was made.

  4. Structural Transitions in Topologically Constrained DNA

    NASA Astrophysics Data System (ADS)

    Leger, J.; Romano, G.; Sarkar, A.; Robert, J.; Bourdieu, L.; Chatenay, D.; Marko, J. F.

    2000-03-01

    We propose a theoretical explanation for results of recent single molecule micromanipulation experiments (Leger et al, PRL 83, 1066, 1999) on double-stranded DNA with fixed linking number. The topological constraint leads to novel structural transitions, including a shift of the usual 60 pN B-form to S-form transition force plateau up to a force of 100 pN when linking is fixed at zero. Our model needs five distinct states to explain the four different observed transitions. The various constant-force plateaus observed for different fixed values of linking correspond to a mixture of different pairs of states, weighted to satisfy the topological constraint. Our model allows us to conclude that sufficiently overtwisted DNA (positive linkage number) undergoes a transition from B-form DNA to a mixture of S-form and P-form DNA at a force plateau near 45 pN, and then to homogeneous P-form DNA at a force plateau near 110 pN. A similar two-step transition occurs for undertwisted DNA, and by analysing the twisting necessary to produce pure S-form DNA we conclude that the S-state has helix repeat of 38 bp. Support from the Whitaker Foundation, the NSF, the ACS-PRF and Research Corporation is gratefully acknowledged.

  5. Honokiol induces a necrotic cell death through the mitochondrial permeability transition pore.

    PubMed

    Li, Ling; Han, Weidong; Gu, Ying; Qiu, Shuang; Lu, Qinghua; Jin, Jie; Luo, Jianhong; Hu, Xun

    2007-05-15

    Previous reports have shown that honokiol induces apoptosis in numerous cancer cell lines and showed preclinical efficacies against apoptosis-resistant B-cell chronic lymphocytic leukemia and multiple myeloma cells from relapse-refractory patients. Here, we show that honokiol can induce a cell death distinct from apoptosis in HL60, MCF-7, and HEK293 cell lines. The death was characterized by a rapid loss of integrity of plasma membrane without externalization of phosphatidyl serine. The broad caspase inhibitor z-VAD-fmk failed to prevent this cell death. Consistently, caspase activation and DNA laddering were not observed. The death was paralleled by a rapid loss of mitochondrial membrane potential, which was mechanistically associated with the mitochondrial permeability transition pore regulated by cyclophilin D (CypD) based on the following evidence: (a) cyclosporin A, an inhibitor of CypD (an essential component of the mitochondrial permeability transition pore), effectively prevented honokiol-induced cell death and loss of mitochondrial membrane potential; (b) inhibition of CypD by RNA interference blocked honokiol-induced cell death; (c) CypD up-regulated by honokiol was correlated with the death rates in HL60, but not in K562 cells, which underwent apoptosis after being exposed to honokiol. We further showed that honokiol induced a CypD-regulated death in primary human acute myelogenous leukemia cells, overcame Bcl-2 and Bcl-X(L)-mediated apoptotic resistance, and was effective against HL60 cells in a pilot in vivo study. To the best of our knowledge, this is the first report to document an induction of mitochondrial permeability transition pore-associated cell death by honokiol.

  6. Mitochondrial DNA diversity in the African American population

    PubMed Central

    Johnson, Derek C.; Shrestha, Sadeep; Wiener, Howard W.; Makowsky, Robert; Kurundkar, Ashish; Wilson, Craig M.; Aissani, Brahim

    2014-01-01

    Genetic polymorphism along mitochondrial DNA (mtDNA) defines population-specific signatures called mtDNA haplogroups. Estimation of mtDNA haplogroup distribution may be prone to errors, notably if the study sample is not drawn from a multicenter cohort. Here, we report on mtDNA diversity in a sample of African American individuals (n = 343) enrolled in a multicenter cohort. Sequencing of the hypervariable regions I and II of the D-loop control region showed that the most common mitochondrial variants are 73G, 146C, 150T, 152C, 189G, 16278T, and 16311C. In agreement with the published data, we observed 17 common mtDNA haplogroups: L0, L1, L1b, L1c, L2, L2a, L2b, L2c, L2e, L3, L3b, L3d, L3e, L3f, L3h, L3x, and L4. The most commonly observed haplogroup is L2a (19.8%), followed by L1b (10.2%). Overall, the observed mtDNA haplogroup distribution in our study is similar to those published for the African American and the African populations. PMID:24102597

  7. Natural radioactivity and human mitochondrial DNA mutations

    PubMed Central

    Forster, Lucy; Forster, Peter; Lutz-Bonengel, Sabine; Willkomm, Horst; Brinkmann, Bernd

    2002-01-01

    Radioactivity is known to induce tumors, chromosome lesions, and minisatellite length mutations, but its effects on the DNA sequence have not previously been studied. A coastal peninsula in Kerala (India) contains the world's highest level of natural radioactivity in a densely populated area, offering an opportunity to characterize radiation-associated DNA mutations. We sampled 248 pedigrees (988 individuals) in the high-radiation peninsula and in nearby low-radiation islands as a control population. We sequenced their mtDNA, and found that the pedigrees living in the high-radiation area have significantly (P < 0.01) increased germ-line point mutations between mothers and their offspring. In each mutation case, we confirmed maternity by autosomal profiling. Strikingly, the radioactive conditions accelerate mutations at nucleotide positions that have been evolutionary hot spots for at least 60,000 years. PMID:12370437

  8. Physiological roles of the mitochondrial permeability transition pore

    PubMed Central

    Mnatsakanyan, Nelli; Beutner, Gisela; Porter, George A.; Alavian, Kambiz N.

    2016-01-01

    Neurons experience high metabolic demand during such processes as synaptic vesicle recycling, membrane potential maintenance and Ca2+ exchange/extrusion. The energy needs of these events are met in large part by mitochondrial production of ATP through the process of oxidative phosphorylation. The job of ATP production by the mitochondria is performed by the F1FO ATP synthase, a multi-protein enzyme that contains a membrane-inserted portion, an extra-membranous enzymatic portion and an extensive regulatory complex. Although required for ATP production by mitochondria, recent findings have confirmed that the membrane-confined portion of the c-subunit of the ATP synthase also houses a large conductance uncoupling channel, the mitochondrial permeability transition pore (mPTP), the persistent opening of which produces osmotic dysregulation of the inner mitochondrial membrane, uncoupling of oxidative phosphorylation and cell death. Recent advances in understanding the molecular components of mPTP and its regulatory mechanisms have determined that decreased uncoupling occurs in states of enhanced mitochondrial efficiency; relative closure of mPTP therefore contributes to cellular functions as diverse as cardiac development and synaptic efficacy. PMID:26868013

  9. CDK1 Enhances Mitochondrial Bioenergetics for Radiation-Induced DNA Repair

    PubMed Central

    Qin, Lili; Fan, Ming; Candas, Demet; Jiang, Guochun; Papadopoulos, Stelios; Tian, Lin; Woloschak, Gayle; Grdina, David J.; Li, Jian Jian

    2015-01-01

    SUMMARY Nuclear DNA repair capacity is a critical determinant of cell fate under genotoxic stress conditions. DNA repair is a well-defined energy consuming process; however, it is unclear how DNA repair is fueled and whether mitochondrial energy production contributes to nuclear DNA repair. Here, we report a dynamic enhancement of oxygen consumption and mitochondrial ATP generation in irradiated normal cells, paralleled with increased mitochondrial relocation of cell cycle kinase CDK1 and nuclear DNA repair. The basal and radiation-induced mitochondrial ATP generation is significantly reduced in cells harboring CDK1 phosphorylation deficient mutant complex I subunits. Similarly, mitochondrial ATP generation and nuclear DNA repair are also severely compromised in cells harboring mitochondrial-targeted kinase deficient CDK1. These results demonstrate a mechanism governing the communication between mitochondria and nucleus, by which CDK1 boosts mitochondrial bioenergetics to meet the increased cellular fuel demand for DNA repair and cell survival under genotoxic stress. PMID:26670043

  10. Histological correlates of post mortem mitochondrial DNA damage in degraded hair.

    PubMed

    Gilbert, M T P; Janaway, R C; Tobin, D J; Cooper, A; Wilson, A S

    2006-01-27

    We have assessed the histological preservation of naturally degraded human hair shafts, and then assayed each for levels of amplifiable mitochondrial DNA and damage-associated DNA miscoding lesions. The results indicate that as sample histology is altered (i.e. as hairs degrade) levels of amplifiable mitochondrial DNA decrease, but no correlation is seen between histology and absolute levels of mitochondrial DNA miscoding lesions. Nevertheless, amplifiable mitochondrial DNA could be recovered across the complete range of the histological preservation spectrum. However, when template copy number is taken into consideration, a correlation of miscoding lesions with histology is again apparent. These relationships indicate that a potential route for the generation of misleading mitochondrial sequence data exists in samples of poor histology. Therefore, we argue that in the absence of molecular cloning, the histological screening of hair may be necessary in order to confirm the reliability of mitochondrial DNA sequences amplified from hair, and thus represents a useful tool in forensic mitochondrial DNA analyses.

  11. Homologous DNA strand exchange activity of the human mitochondrial DNA helicase TWINKLE

    PubMed Central

    Sen, Doyel; Patel, Gayatri; Patel, Smita S.

    2016-01-01

    A crucial component of the human mitochondrial DNA replisome is the ring-shaped helicase TWINKLE—a phage T7-gene 4-like protein expressed in the nucleus and localized in the human mitochondria. Our previous studies showed that despite being a helicase, TWINKLE has unique DNA annealing activity. At the time, the implications of DNA annealing by TWINKLE were unclear. Herein, we report that TWINKLE uses DNA annealing function to actively catalyze strand-exchange reaction between the unwinding substrate and a homologous single-stranded DNA. Using various biochemical experiments, we demonstrate that the mechanism of strand-exchange involves active coupling of unwinding and annealing reactions by the TWINKLE. Unlike strand-annealing, the strand-exchange reaction requires nucleotide hydrolysis and greatly stimulated by short region of homology between the recombining DNA strands that promote joint molecule formation to initiate strand-exchange. Furthermore, we show that TWINKLE catalyzes branch migration by resolving homologous four-way junction DNA. These four DNA modifying activities of TWINKLE: strand-separation, strand-annealing, strand-exchange and branch migration suggest a dual role of TWINKLE in mitochondrial DNA maintenance. In addition to playing a major role in fork progression during leading strand DNA synthesis, we propose that TWINKLE is involved in recombinational repair of the human mitochondrial DNA. PMID:26887820

  12. Mitochondrial DNA mutations in single human blood cells.

    PubMed

    Yao, Yong-Gang; Kajigaya, Sachiko; Young, Neal S

    2015-09-01

    Determination mitochondrial DNA (mtDNA) sequences from extremely small amounts of DNA extracted from tissue of limited amounts and/or degraded samples is frequently employed in medical, forensic, and anthropologic studies. Polymerase chain reaction (PCR) amplification followed by DNA cloning is a routine method, especially to examine heteroplasmy of mtDNA mutations. In this review, we compare the mtDNA mutation patterns detected by three different sequencing strategies. Cloning and sequencing methods that are based on PCR amplification of DNA extracted from either single cells or pooled cells yield a high frequency of mutations, partly due to the artifacts introduced by PCR and/or the DNA cloning process. Direct sequencing of PCR product which has been amplified from DNA in individual cells is able to detect the low levels of mtDNA mutations present within a cell. We further summarize the findings in our recent studies that utilized this single cell method to assay mtDNA mutation patterns in different human blood cells. Our data show that many somatic mutations observed in the end-stage differentiated cells are found in hematopoietic stem cells (HSCs) and progenitors within the CD34(+) cell compartment. Accumulation of mtDNA variations in the individual CD34+ cells is affected by both aging and family genetic background. Granulocytes harbor higher numbers of mutations compared with the other cells, such as CD34(+) cells and lymphocytes. Serial assessment of mtDNA mutations in a population of single CD34(+) cells obtained from the same donor over time suggests stability of some somatic mutations. CD34(+) cell clones from a donor marked by specific mtDNA somatic mutations can be found in the recipient after transplantation. The significance of these findings is discussed in terms of the lineage tracing of HSCs, aging effect on accumulation of mtDNA mutations and the usage of mtDNA sequence in forensic identification.

  13. Directly repeated sequences associated with pathogenic mitochondrial DNA deletions.

    PubMed Central

    Johns, D R; Rutledge, S L; Stine, O C; Hurko, O

    1989-01-01

    We determined the nucleotide sequences of junctional regions associated with large deletions of mitochondrial DNA found in four unrelated individuals with a phenotype of chronic progressive external ophthalmoplegia. In each patient, the deletion breakpoint occurred within a directly repeated sequence of 13-18 base pairs, present in different regions of the normal mitochondrial genome-separated by 4.5-7.7 kilobases. In two patients, the deletions were identical. When all four repeated sequences are compared, a consensus sequence of 11 nucleotides emerges, similar to putative recombination signals, suggesting the involvement of a recombinational event. Partially deleted and normal mitochondrial DNAs were found in all tissues examined, but in very different proportions, indicating that these mutations originated before the primary cell layers diverged. Images PMID:2813377

  14. Ethical aspects of nuclear and mitochondrial DNA transfer.

    PubMed

    Blesa, José Rafael; Tudela, Julio; Aznar, Justo

    2016-05-01

    Somatic cell nuclear transfer (SCNT) (cloning), as a reproductive or therapeutic method, and mitochondrial DNA transfer, as a method to prevent the transmission of mitochondrial diseases, are analyzed in this paper from a bioethics perspective. The licit purpose of being able to treat certain diseases, as in the case of SCNT, cannot justify, in any case, resorting to illicit means such as the manipulation, selection, and elimination of human embryos in the blastocyst phase, by using cell lines obtained from them. Crossing this line paves the way (as utilitarian ethics advocates) to assuming any cost in scientific experimentation so long as satisfactory results are obtained. With mitochondrial replacement, either human embryos are directly manipulated (pronuclear transfer) or germline cells are manipulated (maternal spindle transfer); changes in these could be transmitted to the offspring.

  15. Mitochondrial calcium and the permeability transition in cell death.

    PubMed

    Lemasters, John J; Theruvath, Tom P; Zhong, Zhi; Nieminen, Anna-Liisa

    2009-11-01

    Dysregulation of Ca(2+) has long been implicated to be important in cell injury. A Ca(2+)-linked process important in necrosis and apoptosis (or necrapoptosis) is the mitochondrial permeability transition (MPT). In the MPT, large conductance permeability transition (PT) pores open that make the mitochondrial inner membrane abruptly permeable to solutes up to 1500 Da. The importance of Ca(2+) in MPT induction varies with circumstance. Ca(2+) overload is sufficient to induce the MPT. By contrast after ischemia-reperfusion to cardiac myocytes, Ca(2+) overload is the consequence of bioenergetic failure after the MPT rather than its cause. In other models, such as cytotoxicity from Reye-related agents and storage-reperfusion injury to liver grafts, Ca(2+) appears to be permissive to MPT onset. Lastly in oxidative stress, increased mitochondrial Ca(2+) and ROS generation act synergistically to produce the MPT and cell death. Thus, the exact role of Ca(2+) for inducing the MPT and cell death depends on the particular biologic setting.

  16. Collated mutations in mitochondrial DNA (mtDNA) depletion syndrome (excluding the mitochondrial gamma polymerase, POLG1).

    PubMed

    Poulton, J; Hirano, M; Spinazzola, A; Arenas Hernandez, M; Jardel, C; Lombès, A; Czermin, B; Horvath, R; Taanman, J W; Rotig, A; Zeviani, M; Fratter, C

    2009-12-01

    These tables list both published and a number of unpublished mutations in genes associated with early onset defects in mitochondrial DNA (mtDNA) maintenance including C10orf2, SUCLG1, SUCLA2, TYMP, RRM2B, MPV17, DGUOK and TK2. The list should not be taken as evidence that any particular mutation is pathogenic. We have included genes known to cause mtDNA depletion, excluding POLG1, because of the existing database (http://tools.niehs.nih.gov/polg/). We have also excluded mutations in C10orf2 associated with dominant adult onset disorders.

  17. Deciphering the spectrum of somatic mutations in the entire mitochondrial DNA genome.

    PubMed

    Chen, X Z; Fang, Y; Shi, Y H; Cui, J H; Li, L Y; Xu, Y C; Ling, B

    2015-04-30

    The mitochondrion is a crucial intracellular organelle responsible for regulating cellular energy metabolism, producing free radicals, initiating and executing the apoptotic pathways. Previous studies have shown that somatic mutations in mitochondrial DNA are associated with various tumors, which may be involved during carcinogenesis and tumor progression. To examine the mutation pattern in cancer, 625 reported somatic mutations in the mitochondrial DNA genome were analyzed. We found that, except for deletions and insertions, most somatic mutations were point mutations, accounting for 89.44% of somatic mutations. Transition was the predominant form of somatic mutation in the entire mitochondrial DNA genome, accounting for 87.12% of point mutations, most of which were homoplastic. Frequency statistics analysis of point mutations indicated that, except for 3 tRNA genes, the mutations were distributed on all resting genes and in the D-loop region, with the latter showing the highest frequency of somatic mutation (19.34%), followed by the tRNA leucine 2 gene and non-coding regions between base pairs 5892 and 5903, while 13 coding-region genes and 2 rRNA genes showed a relatively lower frequency of somatic point mutations. Nonsynonymous mutations and terminal amino acid changes were the primary point somatic mutations detected from 13 coding-region genes, which may cause mitochondrial dysfunction in cancer cells. We found that the somatic mutations may affect the mitochondrial DNA genome; the non-coding region should be examined to identify somatic mutations as potential diagnostic biomarkers for early detection of cancer.

  18. Phylogenetic position of a copper age sheep (Ovis aries) mitochondrial DNA.

    PubMed

    Olivieri, Cristina; Ermini, Luca; Rizzi, Ermanno; Corti, Giorgio; Luciani, Stefania; Marota, Isolina; De Bellis, Gianluca; Rollo, Franco

    2012-01-01

    Sheep (Ovis aries) were domesticated in the Fertile Crescent region about 9,000-8,000 years ago. Currently, few mitochondrial (mt) DNA studies are available on archaeological sheep. In particular, no data on archaeological European sheep are available. Here we describe the first portion of mtDNA sequence of a Copper Age European sheep. DNA was extracted from hair shafts which were part of the clothes of the so-called Tyrolean Iceman or Ötzi (5,350-5,100 years before present). Mitochondrial DNA (a total of 2,429 base pairs, encompassing a portion of the control region, tRNA(Phe), a portion of the 12S rRNA gene, and the whole cytochrome B gene) was sequenced using a mixed sequencing procedure based on PCR amplification and 454 sequencing of pooled amplification products. We have compared the sequence with the corresponding sequence of 334 extant lineages. A phylogenetic network based on a new cladistic notation for the mitochondrial diversity of domestic sheep shows that the Ötzi's sheep falls within haplogroup B, thus demonstrating that sheep belonging to this haplogroup were already present in the Alps more than 5,000 years ago. On the other hand, the lineage of the Ötzi's sheep is defined by two transitions (16147, and 16440) which, assembled together, define a motif that has not yet been identified in modern sheep populations.

  19. Phylogenetic Position of a Copper Age Sheep (Ovis aries) Mitochondrial DNA

    PubMed Central

    Olivieri, Cristina; Ermini, Luca; Rizzi, Ermanno; Corti, Giorgio; Luciani, Stefania; Marota, Isolina; De Bellis, Gianluca; Rollo, Franco

    2012-01-01

    Background Sheep (Ovis aries) were domesticated in the Fertile Crescent region about 9,000-8,000 years ago. Currently, few mitochondrial (mt) DNA studies are available on archaeological sheep. In particular, no data on archaeological European sheep are available. Methodology/Principal Findings Here we describe the first portion of mtDNA sequence of a Copper Age European sheep. DNA was extracted from hair shafts which were part of the clothes of the so-called Tyrolean Iceman or Ötzi (5,350 - 5,100 years before present). Mitochondrial DNA (a total of 2,429 base pairs, encompassing a portion of the control region, tRNAPhe, a portion of the 12S rRNA gene, and the whole cytochrome B gene) was sequenced using a mixed sequencing procedure based on PCR amplification and 454 sequencing of pooled amplification products. We have compared the sequence with the corresponding sequence of 334 extant lineages. Conclusions/Significance A phylogenetic network based on a new cladistic notation for the mitochondrial diversity of domestic sheep shows that the Ötzi's sheep falls within haplogroup B, thus demonstrating that sheep belonging to this haplogroup were already present in the Alps more than 5,000 years ago. On the other hand, the lineage of the Ötzi's sheep is defined by two transitions (16147, and 16440) which, assembled together, define a motif that has not yet been identified in modern sheep populations. PMID:22457789

  20. Patterns of mitochondrial DNA instability in Brassica campestris cultured cells.

    PubMed

    Shirzadegan, M; Palmer, J D; Christey, M; Earle, E D

    1991-01-01

    We previously showed that the mitochondrial DNA (mtDNA) of a Brassica campestris callus culture had undergone extensive rearrangements (i.e. large inversions and a duplication) relative to DNA of the control plant [54]. In this study we observed that after continued growth, the mtDNA of this culture continues to change, with rearranged forms amplifying and diminishing to varying proportions. Strikingly similar changes were detected in the mtDNA profiles of a variety of other long- and short-term callus and cell suspension lines. However, the proportions of parental ('unrearranged') and novel ('rearranged') forms varied in different cultured cell mtDNAs. To address the source of this heterogeneity, we compared the mtDNA organization of 28 individual plants from the parental seed stock. With the exception of one plant containing high levels of a novel plasmid-like mtDNA molecule, no significant variation was detected among individual plants and therefore source plant variation is unlikely to have contributed to the diversity of mitochondrial genomes observed in cultured cells. The source of this culture-induced heterogeneity was also investigated in 16 clones derived from single protoplasts. A mixed population of unrearranged and rearranged mtDNA molecules was apparent in each protoclone, suggesting that the observed heterogeneity in various cultures might reflect the genomic composition of each individual cell; however, the induction of an intercellular heterogeneity subsequent to the protoplast isolation was not tested and therefore cannot be ruled out. The results of this study support our earlier model that the rapid structural alteration of B. campestris mtDNA in vitro results from preferential amplification and reassortment of minor pre-existing forms of the genome rather than de novo rearrangement. Infrequent recombination between short dispersed repeated elements is proposed as the underlying mechanism for the formation of these minor mtDNA molecules.

  1. The exonuclease activity of the yeast mitochondrial DNA polymerase γ suppresses mitochondrial DNA deletions between short direct repeats in Saccharomyces cerevisiae.

    PubMed

    Stumpf, Jeffrey D; Copeland, William C

    2013-06-01

    The importance of mitochondrial DNA (mtDNA) deletions in the progeroid phenotype of exonuclease-deficient DNA polymerase γ mice has been intensely debated. We show that disruption of Mip1 exonuclease activity increases mtDNA deletions 160-fold, whereas disease-associated polymerase variants were mostly unaffected, suggesting that exonuclease activity is vital to avoid deletions during mtDNA replication.

  2. Hypertriglyceridemia increases mitochondrial resting respiration and susceptibility to permeability transition.

    PubMed

    Alberici, Luciane C; Oliveira, Helena C F; Bighetti, Eliete J B; de Faria, Eliana C; Degaspari, Giovana R; Souza, Claudio T; Vercesi, Anibal E

    2003-10-01

    High plasma level of triglycerides (TGs) is a common feature in atherosclerosis, obesity, diabetes, alcoholism, stress, and infection. Since mitochondria have been implicated in cell death under a variety of metabolic disorders, we examined liver mitochondrial functions in hypertriglyceridemic transgenic mice. Hypertriglyceridemia increased resting respiration and predisposed to mitochondrial permeability transition (MPT). Ciprofibrate therapy reduced plasma TG levels, normalized respiration, and prevented MPT. The higher resting respiration in transgenic mitochondria remained in the presence of the adenine nucleotide carrier inhibitor, carboxyatractyloside, bovine serum albumin, and the uncoupling proteins (UCPs) inhibitor, GDP. UCP2 content was similar in both control and transgenic mitochondria. We propose that faster resting respiration represents a regulated adaptation to oxidize excess free fatty acid in the transgenic mice.

  3. Divergent evolution of life span associated with mitochondrial DNA evolution.

    PubMed

    Stojković, Biljana; Sayadi, Ahmed; Đorđević, Mirko; Jović, Jelena; Savković, Uroš; Arnqvist, Göran

    2017-01-01

    Mitochondria play a key role in ageing. The pursuit of genes that regulate variation in life span and ageing have shown that several nuclear-encoded mitochondrial genes are important. However, the role of mitochondrial encoded genes (mtDNA) is more controversial and our appreciation of the role of mtDNA for the evolution of life span is limited. We use replicated lines of seed beetles that have been artificially selected for long or short life for >190 generations, now showing dramatic phenotypic differences, to test for a possible role of mtDNA in the divergent evolution of ageing and life span. We show that these divergent selection regimes led to the evolution of significantly different mtDNA haplotype frequencies. Selection for a long life and late reproduction generated positive selection for one specific haplotype, which was fixed in most such lines. In contrast, selection for reproduction early in life led to both positive selection as well as negative frequency-dependent selection on two different haplotypes, which were both present in all such lines. Our findings suggest that the evolution of life span was in part mediated by mtDNA, providing support for the emerging general tenet that adaptive evolution of life-history syndromes may involve mtDNA. © 2016 The Author(s). Evolution © 2016 The Society for the Study of Evolution.

  4. Mitochondrial DNA replication: a PrimPol perspective.

    PubMed

    Bailey, Laura J; Doherty, Aidan J

    2017-04-15

    PrimPol, (primase-polymerase), the most recently identified eukaryotic polymerase, has roles in both nuclear and mitochondrial DNA maintenance. PrimPol is capable of acting as a DNA polymerase, with the ability to extend primers and also bypass a variety of oxidative and photolesions. In addition, PrimPol also functions as a primase, catalysing the preferential formation of DNA primers in a zinc finger-dependent manner. Although PrimPol's catalytic activities have been uncovered in vitro, we still know little about how and why it is targeted to the mitochondrion and what its key roles are in the maintenance of this multicopy DNA molecule. Unlike nuclear DNA, the mammalian mitochondrial genome is circular and the organelle has many unique proteins essential for its maintenance, presenting a differing environment within which PrimPol must function. Here, we discuss what is currently known about the mechanisms of DNA replication in the mitochondrion, the proteins that carry out these processes and how PrimPol is likely to be involved in assisting this vital cellular process. © 2017 The Author(s).

  5. Human mitochondrial DNA and nuclear DNA isolation from food bite marks.

    PubMed

    C Zapico, Sara; Menéndez, Sofía T

    2016-10-01

    Bite mark analysis is used for comparison between bite marks on a bitten object and the suspects' teeth. However, if it is not possible to obtain a correct match, it is important to recover salivary DNA. Previous studies have tried to isolate human nuclear DNA from bitten foods but were not completely successful. In the present work, we studied the efficiency of human nuclear and mitochondrial DNA isolation from bite marks in cheese, a donut and an apple. Using a double swab technique and silica-based DNA extraction kit, nuclear and mitochondrial DNA were isolated. Human housekeeping genes were amplified to analyse the efficiency of nuclear DNA profiling. mtDNA was sequencing and haplogroup assign. Although cheese and apple samples showed the highest concentration of DNA, the purity of DNA on the apple was low. Moreover, apple samples failed to amplify the two human housekeeping genes, GAPDH and RPL22. In contrast, cheese samples have high purity and amplification efficiency. Donut samples showed an intermediate value and low amplification efficiency. In spite of these results, isolation and characterization/sequencing of human mitochondrial DNA was completely successful in the three samples, which pointed out the possibility of identification through this type of DNA. This research indicated that it is possible to recover and isolate human nuclear and mitochondrial DNA from bitten foods, although the quantity and purity of nuclear DNA depends on the type of food. That is of significance important in forensic sciences for the correct identification of a suspect. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. qPCR-based mitochondrial DNA quantification: Influence of template DNA fragmentation on accuracy

    SciTech Connect

    Jackson, Christopher B.; Gallati, Sabina; Schaller, Andre

    2012-07-06

    Highlights: Black-Right-Pointing-Pointer Serial qPCR accurately determines fragmentation state of any given DNA sample. Black-Right-Pointing-Pointer Serial qPCR demonstrates different preservation of the nuclear and mitochondrial genome. Black-Right-Pointing-Pointer Serial qPCR provides a diagnostic tool to validate the integrity of bioptic material. Black-Right-Pointing-Pointer Serial qPCR excludes degradation-induced erroneous quantification. -- Abstract: Real-time PCR (qPCR) is the method of choice for quantification of mitochondrial DNA (mtDNA) by relative comparison of a nuclear to a mitochondrial locus. Quantitative abnormal mtDNA content is indicative of mitochondrial disorders and mostly confines in a tissue-specific manner. Thus handling of degradation-prone bioptic material is inevitable. We established a serial qPCR assay based on increasing amplicon size to measure degradation status of any DNA sample. Using this approach we can exclude erroneous mtDNA quantification due to degraded samples (e.g. long post-exicision time, autolytic processus, freeze-thaw cycles) and ensure abnormal DNA content measurements (e.g. depletion) in non-degraded patient material. By preparation of degraded DNA under controlled conditions using sonification and DNaseI digestion we show that erroneous quantification is due to the different preservation qualities of the nuclear and the mitochondrial genome. This disparate degradation of the two genomes results in over- or underestimation of mtDNA copy number in degraded samples. Moreover, as analysis of defined archival tissue would allow to precise the molecular pathomechanism of mitochondrial disorders presenting with abnormal mtDNA content, we compared fresh frozen (FF) with formalin-fixed paraffin-embedded (FFPE) skeletal muscle tissue of the same sample. By extrapolation of measured decay constants for nuclear DNA ({lambda}{sub nDNA}) and mtDNA ({lambda}{sub mtDNA}) we present an approach to possibly correct measurements in

  7. Targeting the mitochondrial genome via a dual function MITO-Porter: evaluation of mtDNA levels and mitochondrial function.

    PubMed

    Yamada, Yuma; Harashima, Hideyoshi

    2015-01-01

    Genetic mutations and defects in mitochondrial DNA (mtDNA) are associated with certain types of mitochondrial dysfunction, ultimately resulting in the occurrence of a variety of human diseases. For an effective mitochondrial gene therapy, it will be necessary to deliver therapeutic agents to the innermost mitochondrial space (the mitochondrial matrix), which contains the mtDNA pool. We recently developed a MITO-Porter, a liposome-based nano-carrier that delivers cargo to mitochondria via a membrane-fusion mechanism. Using propidium iodide, as a probe to detect mtDNA, we were able to confirm that the MITO-Porter delivered cargoes to mitochondrial matrices in living cells. More recently, we constructed a Dual Function (DF)-MITO-Porter, a liposome-based nanocarrier for mitochondrial delivery via a stepwise process. In this chapter, we describe the methodology used to deliver bioactive molecules to the mitochondrial matrix using the above DF-MITO-Porter, and the evaluation of mtDNA levels and mitochondrial activities in living cells.

  8. Mitochondrial free [Ca2+] levels and the permeability transition.

    PubMed

    Vay, Laura; Hernández-SanMiguel, Esther; Lobatón, Carmen D; Moreno, Alfredo; Montero, Mayte; Alvarez, Javier

    2009-03-01

    Mitochondrial Ca(2+) activates many processes, from mitochondrial metabolism to opening of the permeability transition pore (PTP) and apoptosis. However, there is considerable controversy regarding the free mitochondrial [Ca(2+)] ([Ca(2+)](M)) levels that can be attained during cell activation or even in mitochondrial preparations. Studies using fluorescent dyes (rhod-2 or similar), have reported that phosphate precipitation precludes [Ca(2+)](M) from increasing above 2-3 microM. Instead, using low-Ca(2+)-affinity aequorin probes, we have measured [Ca(2+)](M) values more than two orders of magnitude higher. We confirm here these values by making a direct in situ calibration of mitochondrial aequorin, and we show that a prolonged increase in [Ca(2+)](M) to levels of 0.5-1mM was actually observed at any phosphate concentration (0-10mM) during continuous perfusion of 3.5-100 microM Ca(2+)-buffers. In spite of this high and maintained (>10 min) [Ca(2+)](M), mitochondria retained functionality and the [Ca(2+)](M) drop induced by a protonophore was fully reversible. In addition, this high [Ca(2+)](M) did not induce PTP opening unless additional activators (phenyl arsine oxide, PAO) were present. PAO induced a rapid, concentration-dependent and irreversible drop in [Ca(2+)](M). In conclusion [Ca(2+)](M) levels of 0.5-1mM can be reached and maintained for prolonged periods (>10 min) in phosphate-containing medium, and massive opening of PTP requires additional pore activators.

  9. Mitochondrial DNA deletions are associated with non-B DNA conformations

    PubMed Central

    Damas, Joana; Carneiro, João; Gonçalves, Joana; Stewart, James B.; Samuels, David C.; Amorim, António; Pereira, Filipe

    2012-01-01

    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. PMID:22661583

  10. Selfish Mitochondrial DNA Proliferates and Diversifies in Small, but not Large, Experimental Populations of Caenorhabditis briggsae

    PubMed Central

    Phillips, Wendy S.; Coleman-Hulbert, Anna L.; Weiss, Emily S.; Howe, Dana K.; Ping, Sita; Wernick, Riana I.; Estes, Suzanne; Denver, Dee R.

    2015-01-01

    Evolutionary interactions across levels of biological organization contribute to a variety of fundamental processes including genome evolution, reproductive mode transitions, species diversification, and extinction. Evolutionary theory predicts that so-called “selfish” genetic elements will proliferate when the host effective population size (Ne) is small, but direct tests of this prediction remain few. We analyzed the evolutionary dynamics of deletion-containing mitochondrial DNA (ΔmtDNA) molecules, previously characterized as selfish elements, in six different natural strains of the nematode Caenorhabditis briggsae allowed to undergo experimental evolution in a range of population sizes (N = 1, 10, 100, and 1,000) for a maximum of 50 generations. Mitochondrial DNA (mtDNA) was analyzed for replicate lineages at each five-generation time point. Ten different ΔmtDNA molecule types were observed and characterized across generations in the experimental populations. Consistent with predictions from evolutionary theory, lab lines evolved in small-population sizes (e.g., nematode N = 1) were more susceptible to accumulation of high levels of preexisting ΔmtDNA compared with those evolved in larger populations. New ΔmtDNA elements were observed to increase in frequency and persist across time points, but almost exclusively at small population sizes. In some cases, ΔmtDNA levels decreased across generations when population size was large (nematode N = 1,000). Different natural strains of C. briggsae varied in their susceptibilities to ΔmtDNA accumulation, owing in part to preexisting compensatory mtDNA alleles in some strains that prevent deletion formation. This analysis directly demonstrates that the evolutionary trajectories of ΔmtDNA elements depend upon the population-genetic environments and molecular-genetic features of their hosts. PMID:26108490

  11. Complete mitochondrial DNA genome of Polytremis nascens (Lepidoptera: Hesperiidae).

    PubMed

    Jiang, Weibin; Zhu, Jianqing; Yang, Qichang; Zhao, Huidong; Chen, Minghan; He, Haiyan; Yu, Weidong

    2016-09-01

    In this study, the complete mitochondrial DNA (mtDNA) sequence of Polytremis nascens (Lepidoptera: Hesperiidae) was determined. The 15,392 bp mitogenome with GenBank accession number KM981865 contained 13 protein genes, 22 tRNAs, 2 rRNAs, and a non-coding control region (D-loop). All the 37 typical animal mitochondrial genes were found. The overall base composition was 39.7% A, 40.7% T, 7.7% G and 11.9% C, with a high A + T content (80.4%). This complete mitogenome of P. nascens provides a basic data for studies on species identification, molecular systematics and conservation genetics.

  12. Analysis of Translesion DNA Synthesis by the Mitochondrial DNA Polymerase γ

    PubMed Central

    Copeland, William C.; Kasiviswanathan, Rajesh; Longley, Matthew J.

    2016-01-01

    Summary Mitochondrial DNA is replicated by the nuclear encoded DNA polymerase γ (pol γ) which is composed of a single 140 kDa catalytic subunit and a dimeric 55 kDa accessory subunit. Mitochondrial DNA is vulnerable to various forms of damage, including several types of oxidative lesions, UV-induced photoproducts, chemical adducts from environmental sources, as well as alkylation and inter-strand crosslinks from chemotherapy agents. Although many of these lesions block DNA replication, Pol γ can bypass some lesions by nucleotide incorporation opposite a template lesion and further extension of the DNA primer past the lesion. This process of translesion synthesis (TLS) by Pol γ can occur in either an error-free or an error-prone manner. Assessment of TLS requires extensive analysis of oligonucleotide substrates and replication products by denaturing polyacrylamide sequencing gels. This chapter presents protocols for the analysis of translesion DNA synthesis. PMID:26530671

  13. An improved test for Africanized honeybee mitochondrial DNA.

    PubMed

    Crozier, Y C; Koulianos, S; Crozier, R H

    1991-09-15

    Mitochondrial DNA derived from Apis mellifera scutellata, the ancestor of the Africanized bees of the New World, lacks a BglII restriction site found in other types of honeybee. We present primers allowing amplification of a 485-bp section of the cytochrome b gene containing this site, using the polymerase chain reaction. Digestion of the amplified product with BglII yields contrasting patterns between Africanized and other honeybees.

  14. Mutagenic effect of freezing on mitochondrial DNA of Saccharomyces cerevisiae.

    PubMed

    Stoycheva, T; Venkov, P; Tsvetkov, Ts

    2007-06-01

    Although suggested in some studies, the mutagenic effect of freezing has not been proved by induction and isolation of mutants. Using a well-defined genetic model, we supply in this communication evidence for the mutagenic effect of freezing on mitochondrial DNA (mtDNA) of the yeast Saccharomyces cerevisiae. The cooling for 2 h at +4 degrees C, followed by freezing for 1 h at -10 degrees C and 16 h at -20 degrees C resulted in induction of respiratory mutations. The immediate freezing in liquid nitrogen was without mutagenic effect. The study of the stepwise procedure showed that the induction of respiratory mutants takes place during the freezing at -10 and -20 degrees C of cells pre-cooled at +4 degrees C. The genetic crosses of freeze-induced mutants evidenced their mitochondrial rho- origin. The freeze-induced rho- mutants are most likely free of simultaneous nuclear mutations. The extracellular presence of cryoprotectants did not prevent the mutagenic effect of freezing while accumulation of cryoprotectors inside cells completely escaped mtDNA from cryodamage. Although the results obtained favor the notion that the mutagenic effect of freezing on yeast mtDNA is due to formation and growth of intracellular ice crystals, other reasons, such as impairment of mtDNA replication or elevated levels of ROS production are discussed as possible explanations of the mutagenic effect of freezing. It is concluded that: (i) freezing can be used as a method for isolation of mitochondrial mutants in S. cerevisiae and (ii) given the substantial development in cryopreservation of cells and tissues, special precautions should be made to avoid mtDNA damage during the cryopreservation procedures.

  15. Geographic variation of human mitochondrial DNA from Papua New Guinea

    SciTech Connect

    Stoneking, M.; Wilson, A.C. ); Jorde, L.B. ); Bhatia, K. )

    1990-03-01

    High resolution mitochondrial DNA (mtDNA) restriction maps, consisting of an average of 370 sites per mtDNA map, were constructed for 119 people from 25 localities in Papua, New Guinea (PNG). Comparison of these PNG restriction maps to published maps from Australian, Caucasian, Asian and African mtDNAs reveals that PNG has the lowest amount of mtDNA variation, and that PNG mtDNA lineages originated from Southeast Asia. The statistical significance of geographic structuring of populations with respect to mtDNA was assessed by comparing observed G{sub ST} values to a distribution of G{sub ST} values generated by random resampling of the data. These analyses show that there is significant structuring of mtDNA variation among worldwide populations, between highland and coastal PNG populations, and even between two highland PNG populations located approximately 200 km apart. However, coastal PNG populations are essentially panmictic, despite being spread over several hundred kilometers. The high resolution technique for examining mtDNA variation, coupled with extensive geographic sampling within a single defined area, leads to an enhanced understanding of the influence of geography on mtDNA variation in human populations.

  16. Complete mitochondrial DNA replacement in a Lake Tanganyika cichlid fish.

    PubMed

    Nevado, B; Koblmüller, S; Sturmbauer, C; Snoeks, J; Usano-Alemany, J; Verheyen, E

    2009-10-01

    We used nuclear and mitochondrial DNA (mtDNA) sequences from specimens collected throughout Lake Tanganyika to clarify the evolutionary relationship between Lamprologus callipterus and Neolamprologus fasciatus. The nuclear data support the reciprocal monophyly of these two shell-breeding lamprologine cichlids. However, mtDNA sequences show that (i) L. callipterus includes two divergent and geographically disjunct (North-South) mtDNA lineages; and that (ii) N. fasciatus individuals cluster in a lineage sister group to the northern lineage of L. callipterus. The two mtDNA lineages of L. callipterus diverged c. 684 kya to 1.2 Ma, coinciding with a major water level low stand in Lake Tanganyika, which divided the lake into isolated sub-lakes. This suggests that the two mtDNA lineages originated as the result of the separation of L. callipterus populations in different sub-basins. The incongruent phylogenetic position of N. fasciatus can best be explained by an ancient unidirectional introgression from L. callipterus into N. fasciatus. Remarkably, our data indicate that this event resulted in the complete mtDNA replacement in N. fasciatus. Our data suggest that hybridization occurred soon after the divergence of the two L. callipterus mtDNA lineages, probably still during the water level low stand, and that subsequently the invading mtDNA lineage spread throughout the lake.

  17. Association Between Mitochondrial DNA Haplogroup Variation and Autism Spectrum Disorders.

    PubMed

    Chalkia, Dimitra; Singh, Larry N; Leipzig, Jeremy; Lvova, Maria; Derbeneva, Olga; Lakatos, Anita; Hadley, Dexter; Hakonarson, Hakon; Wallace, Douglas C

    2017-08-23

    Autism spectrum disorders (ASD) are characterized by impairments in social interaction, communication, and repetitive or restrictive behavior. Although multiple physiologic and biochemical studies have reported defects in mitochondrial oxidative phosphorylation in patients with ASD, the role of mitochondrial DNA (mtDNA) variation has remained relatively unexplored. To assess what impact mitochondrial lineages encompassing ancient mtDNA functional polymorphisms, termed haplogroups, have on ASD risk. In this cohort study, individuals with autism and their families were studied using the Autism Genetic Resource Exchange cohort genome-wide association studies data previously generated at the Children's Hospital of Philadelphia. From October 2010 to January 2017, we analyzed the data and used the mtDNA single-nucleotide polymorphisms interrogated by the Illumina HumanHap 550 chip to determine the mtDNA haplogroups of the individuals. Taking into account the familial structure of the Autism Genetic Resource Exchange data, we then determined whether the mtDNA haplogroups correlate with ASD risk. Odds ratios of mitochondrial haplogroup as predictors of ASD risk. Of 1624 patients with autism included in this study, 1299 were boys (80%) and 325 were girls (20%). Families in the Autism Genetic Resource Exchange collection (933 families, encompassing 4041 individuals: 1624 patients with ASD and 2417 healthy parents and siblings) had been previously recruited in the United States with no restrictions on age, sex, race/ethnicity, or socioeconomic status. Relative to the most common European haplogroup HHV, European haplogroups I, J, K, O-X, T, and U were associated with increased risk of ASD, as were Asian and Native American haplogroups A and M, with odds ratios ranging from 1.55 (95% CI, 1.16-2.06) to 2.18 (95% CI, 1.59-3) (adjusted P < .04). Hence, mtDNA haplogroup variation is an important risk factor for ASD. Because haplogroups I, J, K, O-X, T, and U encompass 55% of the

  18. Levodopa response in Parkinsonism with multiple mitochondrial DNA deletions.

    PubMed

    Wilcox, Robert A; Churchyard, Andrew; Dahl, Henrik H; Hutchison, Wendy M; Kirby, Denise M; Thyagarajan, Dominic

    2007-05-15

    We report a patient with an autosomal dominant chronic progressive external ophthalmoplegia phenotype associated with multiple mtDNA deletions in muscle from a family in which linkage analysis excluded mutations in DNA polymerase gamma (POLG), adenine nucleotide translocase (ANT-1) or C10orf2 (Twinkle). She presented with prominent Parkinsonism characterized by prolonged benefit from levodopa (L-dopa) and the later development of L-dopa induced dyskinesias and motor fluctuations. Thus L-dopa responsiveness, L-dopa induced dyskinesias and motor fluctuations may also occur in atypical Parkinsonism of mitochondrial disease, just as they may in multiple system atrophy.

  19. Mitochondrial DNA sequences from a 7000-year old brain.

    PubMed Central

    Pääbo, S; Gifford, J A; Wilson, A C

    1988-01-01

    Pieces of mitochondrial DNA from a 7000-year-old human brain were amplified by the polymerase chain reaction and sequenced. Albumin and high concentrations of polymerase were required to overcome a factor in the brain extract that inhibits amplification. For this and other sources of ancient DNA, we find an extreme inverse dependence of the amplification efficiency on the length of the sequence to be amplified. This property of ancient DNA distinguishes it from modern DNA and thus provides a new criterion of authenticity for use in research on ancient DNA. The brain is from an individual recently excavated from Little Salt Spring in southwestern Florida and the anthropologically informative sequences it yielded are the first obtained from archaeologically retrieved remains. The sequences show that this ancient individual belonged to a mitochondrial lineage that is rare in the Old World and not previously known to exist among Native Americans. Our finding brings to three the number of maternal lineages known to have been involved in the prehistoric colonization of the New World. Images PMID:3186445

  20. Fatal dilated cardiomyopathy associated with a mitochondrial DNA deletion.

    PubMed

    Moslemi, A R; Selimovic, N; Bergh, C H; Oldfors, A

    2000-01-01

    A 27-year-old man was admitted to hospital because of severe cardiac failure. Investigation revealed dilated cardiomyopathy with a left ventricular ejection fraction of 15-20%. During adolescence the patient had been investigated for growth retardation and he also had progressive external ophthalmoplegia. There had been no symptoms of cardiac disease until 2 weeks before admittance. An endomyocardial biopsy showed cardiomyocytes deficient in cytochrome c oxidase (COX) in a mosaic pattern. A skeletal muscle biopsy showed mitochondrial myopathy with COX-deficient ragged-red fibers. Molecular genetic analysis revealed a heteroplasmic, 3.8-kb, mitochondrial DNA (mtDNA) deletion in heart and muscle. PCR-based quantification of the proportion of mtDNA with deletion showed 47% mutated mtDNA in the myocardial biopsy and 68% in muscle. In spite of treatment, the condition deteriorated and the patient died 5 days after admittance. This case demonstrates that mtDNA deletions may occasionally be the cause of severe dilated cardiomyopathy, and that morphological and molecular genetic diagnosis may be obtained by endomyocardial biopsy. Copyright 2000 S. Karger AG, Basel.

  1. Mitochondrial DNA Variation in Southeastern Pre-Columbian Canids

    PubMed Central

    DeBiasse, Melissa B.; Rabon, David R.; Chamberlain, Michael J.; Taylor, Sabrina S.

    2016-01-01

    The taxonomic status of the red wolf (Canis rufus) is heavily debated, but could be clarified by examining historic specimens from the southeastern United States. We analyzed mitochondrial DNA (mtDNA) from 3 ancient (350–1900 year olds) putative wolf samples excavated from middens and sinkholes within the historic red wolf range. We detected 3 unique mtDNA haplotypes, which grouped with the coyote mtDNA clade, suggesting that the canids inhabiting southeastern North America prior to human colonization from Europe were either coyotes, which would vastly expand historic coyote distributions, an ancient coyote–wolf hybrid, or a North American evolved red wolf lineage related to coyotes. Should the red wolf prove to be a distinct species, our results support the idea of either an ancient hybrid origin for red wolves or a shared common ancestor between coyotes and red wolves. PMID:26774058

  2. Relative patterns and rates of evolution in heron nuclear and mitochondrial DNA.

    PubMed

    Sheldon, F H; Jones, C E; McCracken, K G

    2000-03-01

    Mitochondrial cytochrome b sequence data from 15 species of herons (Aves: Ardeidae), representing 13 genera, were compared with DNA hybridization data of single-copy nuclear DNA (scnDNA) from the same species in a taxonomic congruence assessment of heron phylogeny. The two data sets produced a partially resolved, completely congruent estimate of phylogeny with the following basic structure: (Tigrisoma, Cochlearius, (((Zebrilus, (Ixobrychus, Botaurus)), (((Ardea, Casmerodius), Bubulcus), ((Egretta thula, Egretta caerulea, Egretta tricolor), Syrigma), Butorides, Nycticorax, Nyctanassa)))). Because congruence indicated similar phylogenetic information in the two data sets, we used the relatively unsaturated DNA hybridization distances as surrogates of time to examine graphically the patterns and rates of change in cytochrome b distances. Cytochrome b distances were computed either from whole sequences or from partitioned sequences consisting of transitions, transversions, specific codon site positions, or specific protein-coding regions. These graphical comparisons indicated that unpartitioned cytochrome b has evolved at 5-10 times the rate of scnDNA. Third-position transversions appeared to offer the most useful sequence partition for phylogenetic analysis because of their relatively fast rate of substitution (two times that of scnDNA) and negligible saturation. We also examined lineage-based rates of evolution by comparing branch length patterns between the nuclear and cytochrome b trees. The degree of correlation in corresponding branch lengths between cytochrome b and DNA hybridization trees depended on DNA sequence partitioning. When cytochrome b sequences were not partitioned, branch lengths in the cytochrome b and DNA hybridization trees were not correlated. However, when cytochrome b sequences were reduced to third-position transversions (i.e., unsaturated, relatively fast changing data), branch lengths were correlated. This finding suggests that lineage

  3. Primer retention owing to the absence of RNase H1 is catastrophic for mitochondrial DNA replication.

    PubMed

    Holmes, J Bradley; Akman, Gokhan; Wood, Stuart R; Sakhuja, Kiran; Cerritelli, Susana M; Moss, Chloe; Bowmaker, Mark R; Jacobs, Howard T; Crouch, Robert J; Holt, Ian J

    2015-07-28

    Encoding ribonuclease H1 (RNase H1) degrades RNA hybridized to DNA, and its function is essential for mitochondrial DNA maintenance in the developing mouse. Here we define the role of RNase H1 in mitochondrial DNA replication. Analysis of replicating mitochondrial DNA in embryonic fibroblasts lacking RNase H1 reveals retention of three primers in the major noncoding region (NCR) and one at the prominent lagging-strand initiation site termed Ori-L. Primer retention does not lead immediately to depletion, as the persistent RNA is fully incorporated in mitochondrial DNA. However, the retained primers present an obstacle to the mitochondrial DNA polymerase γ in subsequent rounds of replication and lead to the catastrophic generation of a double-strand break at the origin when the resulting gapped molecules are copied. Hence, the essential role of RNase H1 in mitochondrial DNA replication is the removal of primers at the origin of replication.

  4. Mitochondrial DNA in somatic cells: a promising target of routine clinical tests.

    PubMed

    Kang, Dongchon; Hamasaki, Naotaka

    2005-08-01

    Alterations of mitochondrial DNA have long been considered only from a point of view of rare genetic disorders causing neuromyopathy. Recently, alterations of mitochondrial DNA have been found in so-called common diseases such as heart failure, diabetes, and cancer; some of these alterations are inherited, and some are generated and/or accumulated in somatic cells with age. Mitochondrial DNA is more vulnerable to alteration than is nuclear DNA. For example, mitochondria produce a large amount of reactive oxygen species as an inevitable byproduct of oxidative phosphorylation. Therefore, mitochondrial DNA is under much stronger oxidative stress than is nuclear DNA. In spite of the importance, it is much less elucidated in the mitochondrial genome than in the nuclear genome how the genome is maintained. In this review, we focus on maintenance of mitochondrial DNA in somatic cells and its clinical importance.

  5. Mitochondrial permeability transition in Ca(2+)-dependent apoptosis and necrosis.

    PubMed

    Rasola, Andrea; Bernardi, Paolo

    2011-09-01

    A variety of stimuli utilize an increase of cytosolic free Ca(2+) concentration as a second messenger to transmit signals, through Ca(2+) release from the endoplasmic reticulum or opening of plasma membrane Ca(2+) channels. Mitochondria contribute to the tight spatiotemporal control of this process by accumulating Ca(2+), thus shaping the return of cytosolic Ca(2+) to resting levels. The rise of mitochondrial matrix free Ca(2+) concentration stimulates oxidative metabolism; yet, in the presence of a variety of sensitizing factors of pathophysiological relevance, the matrix Ca(2+) increase can also lead to opening of the permeability transition pore (PTP), a high conductance inner membrane channel. While transient openings may serve the purpose of providing a fast Ca(2+) release mechanism, persistent PTP opening is followed by deregulated release of matrix Ca(2+), termination of oxidative phosphorylation, matrix swelling with inner membrane unfolding and eventually outer membrane rupture with release of apoptogenic proteins and cell death. Thus, a rise in mitochondrial Ca(2+) can convey both apoptotic and necrotic death signals by inducing opening of the PTP. Understanding the signalling networks that govern changes in mitochondrial free Ca(2+) concentration, their interplay with Ca(2+) signalling in other subcellular compartments, and regulation of PTP has important implications in the fine comprehension of the main biological routines of the cell and in disease pathogenesis.

  6. Contribution of liver mitochondrial membrane-bound glutathione transferase to mitochondrial permeability transition pores

    SciTech Connect

    Hossain, Quazi Sohel; Ulziikhishig, Enkhbaatar; Lee, Kang Kwang; Yamamoto, Hideyuki; Aniya, Yoko

    2009-02-15

    We recently reported that the glutathione transferase in rat liver mitochondrial membranes (mtMGST1) is activated by S-glutathionylation and the activated mtMGST1 contributes to the mitochondrial permeability transition (MPT) pore and cytochrome c release from mitochondria [Lee, K.K., Shimoji, M., Quazi, S.H., Sunakawa, H., Aniya, Y., 2008. Novel function of glutathione transferase in rat liver mitochondrial membrane: role for cytochrome c release from mitochondria. Toxcol. Appl. Pharmacol. 232, 109-118]. In the present study we investigated the effect of reactive oxygen species (ROS), generator gallic acid (GA) and GST inhibitors on mtMGST1 and the MPT. When rat liver mitochondria were incubated with GA, mtMGST1 activity was increased to about 3 fold and the increase was inhibited with antioxidant enzymes and singlet oxygen quenchers including 1,4-diazabicyclo [2,2,2] octane (DABCO). GA-mediated mtMGST1 activation was prevented by GST inhibitors such as tannic acid, hematin, and cibacron blue and also by cyclosporin A (CsA). In addition, GA induced the mitochondrial swelling which was also inhibited by GST inhibitors, but not by MPT inhibitors CsA, ADP, and bongkrekic acid. GA also released cytochrome c from the mitochondria which was inhibited completely by DABCO, moderately by GST inhibitors, and somewhat by CsA. Ca{sup 2+}-mediated mitochondrial swelling and cytochrome c release were inhibited by MPT inhibitors but not by GST inhibitors. When the outer mitochondrial membrane was isolated after treatment of mitochondria with GA, mtMGST1 activity was markedly increased and oligomer/aggregate of mtMGST1 was observed. These results indicate that mtMGST1 in the outer mitochondrial membrane is activated by GA through thiol oxidation leading to protein oligomerization/aggregation, which may contribute to the formation of ROS-mediated, CsA-insensitive MPT pore, suggesting a novel mechanism for regulation of the MPT by mtMGST1.

  7. DNA sequences proximal to human mitochondrial DNA deletion breakpoints prevalent in human disease form G-quadruplexes, a class of DNA structures inefficiently unwound by the mitochondrial replicative Twinkle helicase.

    PubMed

    Bharti, Sanjay Kumar; Sommers, Joshua A; Zhou, Jun; Kaplan, Daniel L; Spelbrink, Johannes N; Mergny, Jean-Louis; Brosh, Robert M

    2014-10-24

    Mitochondrial DNA deletions are prominent in human genetic disorders, cancer, and aging. It is thought that stalling of the mitochondrial replication machinery during DNA synthesis is a prominent source of mitochondrial genome instability; however, the precise molecular determinants of defective mitochondrial replication are not well understood. In this work, we performed a computational analysis of the human mitochondrial genome using the "Pattern Finder" G-quadruplex (G4) predictor algorithm to assess whether G4-forming sequences reside in close proximity (within 20 base pairs) to known mitochondrial DNA deletion breakpoints. We then used this information to map G4P sequences with deletions characteristic of representative mitochondrial genetic disorders and also those identified in various cancers and aging. Circular dichroism and UV spectral analysis demonstrated that mitochondrial G-rich sequences near deletion breakpoints prevalent in human disease form G-quadruplex DNA structures. A biochemical analysis of purified recombinant human Twinkle protein (gene product of c10orf2) showed that the mitochondrial replicative helicase inefficiently unwinds well characterized intermolecular and intramolecular G-quadruplex DNA substrates, as well as a unimolecular G4 substrate derived from a mitochondrial sequence that nests a deletion breakpoint described in human renal cell carcinoma. Although G4 has been implicated in the initiation of mitochondrial DNA replication, our current findings suggest that mitochondrial G-quadruplexes are also likely to be a source of instability for the mitochondrial genome by perturbing the normal progression of the mitochondrial replication machinery, including DNA unwinding by Twinkle helicase.

  8. Haplogrouping mitochondrial DNA sequences in Legal Medicine/Forensic Genetics.

    PubMed

    Bandelt, Hans-Jürgen; van Oven, Mannis; Salas, Antonio

    2012-11-01

    Haplogrouping refers to the classification of (partial) mitochondrial DNA (mtDNA) sequences into haplogroups using the current knowledge of the worldwide mtDNA phylogeny. Haplogroup assignment of mtDNA control-region sequences assists in the focused comparison with closely related complete mtDNA sequences and thus serves two main goals in forensic genetics: first is the a posteriori quality analysis of sequencing results and second is the prediction of relevant coding-region sites for confirmation or further refinement of haplogroup status. The latter may be important in forensic casework where discrimination power needs to be as high as possible. However, most articles published in forensic genetics perform haplogrouping only in a rudimentary or incorrect way. The present study features PhyloTree as the key tool for assigning control-region sequences to haplogroups and elaborates on additional Web-based searches for finding near-matches with complete mtDNA genomes in the databases. In contrast, none of the automated haplogrouping tools available can yet compete with manual haplogrouping using PhyloTree plus additional Web-based searches, especially when confronted with artificial recombinants still present in forensic mtDNA datasets. We review and classify the various attempts at haplogrouping by using a multiplex approach or relying on automated haplogrouping. Furthermore, we re-examine a few articles in forensic journals providing mtDNA population data where appropriate haplogrouping following PhyloTree immediately highlights several kinds of sequence errors.

  9. Mitochondrial DNA copy number in peripheral blood and melanoma risk.

    PubMed

    Shen, Jie; Gopalakrishnan, Vancheswaran; Lee, Jeffrey E; Fang, Shenying; Zhao, Hua

    2015-01-01

    Mitochondrial DNA (mtDNA) copy number in peripheral blood has been suggested as risk modifier in various types of cancer. However, its influence on melanoma risk is unclear. We evaluated the association between mtDNA copy number in peripheral blood and melanoma risk in 500 melanoma cases and 500 healthy controls from an ongoing melanoma study. The mtDNA copy number was measured using real-time polymerase chain reaction. Overall, mean mtDNA copy number was significantly higher in cases than in controls (1.15 vs 0.99, P<0.001). Increased mtDNA copy number was associated with a 1.45-fold increased risk of melanoma (95% confidence interval: 1.12-1.97). Significant joint effects between mtDNA copy number and variables related to pigmentation and history of sunlight exposure were observed. This study supports an association between increased mtDNA copy number and melanoma risk that is independent on the known melanoma risk factors (pigmentation and history of sunlight exposure).

  10. Mitochondrial DNA Sequence Divergence among Lycopersicon and Related Solanum Species

    PubMed Central

    McClean, Phillip E.; Hanson, Maureen R.

    1986-01-01

    Sequence divergence among the mitochondrial (mt) DNA of nine Lycopersicon and two closely related Solanum species was estimated using the shared fragment method. A portion of each mt genome was highlighted by probing total DNA with a series of plasmid clones containing mt-specific DNA fragments from Lycopersicon pennellii. A total of 660 fragments were compared. As calculated by the shared fragment method, sequence divergence among the mtDNAs ranged from 0.4% for the L. esculentum-L. esculentum var. cerasiforme pair to 2.7% for the Solanum rickii-L. pimpinellifolium and L. cheesmanii-L. chilense pairs. The mtDNA divergence is higher than that reported for Lycopersicon chloroplast (cp) DNA, which indicates that the DNAs of the two plant organelles are evolving at different rates. The percentages of shared fragments were used to construct a phenogram that illustrates the present-day relationships of the mtDNAs. The mtDNA-derived phenogram places L. hirsutum closer to L. esculentum than taxonomic and cpDNA comparisons. Further, the recent assignment of L. pennellii to the genus Lycopersicon is supported by the mtDNA analysis. PMID:17246320

  11. Mitochondrial DNA copy number variation across human cancers

    PubMed Central

    Reznik, Ed; Miller, Martin L; Şenbabaoğlu, Yasin; Riaz, Nadeem; Sarungbam, Judy; Tickoo, Satish K; Al-Ahmadie, Hikmat A; Lee, William; Seshan, Venkatraman E; Hakimi, A Ari; Sander, Chris

    2016-01-01

    Mutations, deletions, and changes in copy number of mitochondrial DNA (mtDNA), are observed throughout cancers. Here, we survey mtDNA copy number variation across 22 tumor types profiled by The Cancer Genome Atlas project. We observe a tendency for some cancers, especially of the bladder, breast, and kidney, to be depleted of mtDNA, relative to matched normal tissue. Analysis of genetic context reveals an association between incidence of several somatic alterations, including IDH1 mutations in gliomas, and mtDNA content. In some but not all cancer types, mtDNA content is correlated with the expression of respiratory genes, and anti-correlated to the expression of immune response and cell-cycle genes. In tandem with immunohistochemical evidence, we find that some tumors may compensate for mtDNA depletion to sustain levels of respiratory proteins. Our results highlight the extent of mtDNA copy number variation in tumors and point to related therapeutic opportunities. DOI: http://dx.doi.org/10.7554/eLife.10769.001 PMID:26901439

  12. Immunogenicity of mitochondrial DNA modified by hydroxyl radical.

    PubMed

    Alam, Khurshid; Moinuddin; Jabeen, Suraya

    2007-05-01

    Mitochondria consume about 90 percent of oxygen used by the body, and are a particularly rich source of reactive oxygen species (ROS). In this research communication mitochondrial DNA (mtDNA) was isolated from fresh goat liver and modified in vitro by hydroxyl radical generated from UV irradiation (254 nm) of hydrogen peroxide. As a consequence of hydroxyl radical modification, mtDNA showed hyperchromicity and sensitivity to nuclease S1 digestion as compared to control mtDNA. Animals immunized with mtDNA and ROS-modified mtDNA induced antibodies as detected by direct binding and competition ELISA. The data suggest that immunogenicity of mtDNA got augmented after treatment with hydroxyl radical. IgG isolated from immune sera showed specificity for respective immunogen and cross-reaction with other nucleic acids. Binding of induced antibodies with array of antigens clearly indicates their polyspecific nature. Moreover, the polyspecificity exhibited by induced antibodies is unique in view of similar multiple antigen binding properties of naturally occurring anti-DNA antibodies derived from SLE patients.

  13. Triangulating the provenance of African elephants using mitochondrial DNA

    PubMed Central

    Ishida, Yasuko; Georgiadis, Nicholas J; Hondo, Tomoko; Roca, Alfred L

    2013-01-01

    African elephant mitochondrial (mt) DNA follows a distinctive evolutionary trajectory. As females do not migrate between elephant herds, mtDNA exhibits low geographic dispersal. We therefore examined the effectiveness of mtDNA for assigning the provenance of African elephants (or their ivory). For 653 savanna and forest elephants from 22 localities in 13 countries, 4258 bp of mtDNA was sequenced. We detected eight mtDNA subclades, of which seven had regionally restricted distributions. Among 108 unique haplotypes identified, 72% were found at only one locality and 84% were country specific, while 44% of individuals carried a haplotype detected only at their sampling locality. We combined 316 bp of our control region sequences with those generated by previous trans-national surveys of African elephants. Among 101 unique control region haplotypes detected in African elephants across 81 locations in 22 countries, 62% were present in only a single country. Applying our mtDNA results to a previous microsatellite-based assignment study would improve estimates of the provenance of elephants in 115 of 122 mis-assigned cases. Nuclear partitioning followed species boundaries and not mtDNA subclade boundaries. For taxa such as elephants in which nuclear and mtDNA markers differ in phylogeography, combining the two markers can triangulate the origins of confiscated wildlife products. PMID:23798975

  14. Distinguishing African and European honeybee matrilines using amplified mitochondrial DNA.

    PubMed Central

    Hall, H G; Smith, D R

    1991-01-01

    Previous DNA studies have revealed that feral neotropical African bees have largely retained an African genetic integrity. Additional DNA testing is needed to confirm these findings, to understand the processes responsible, and to follow African bee spread into the temperate United States. To facilitate surveys, the polymerase chain reaction was utilized. African and European honeybee mitochondrial DNA (mtDNA) was identified through amplified segments that carry informative restriction site and length polymorphisms. The ability to discriminate among honeybee subspecies was established by testing a total of 129 colonies from Africa and Europe. Matriline identities could thus be determined for imported New World bees. Among 41 managed and feral colonies in the United States and north Mexico, two European lineages (west and east) were distinguished. From neotropical regions, 72 feral colonies had African mtDNA and 4 had European mtDNA. The results support earlier conclusions that neotropical African bees have spread as unbroken African maternal lineages. Old and New World African honeybee populations exhibit different frequencies of a mtDNA length polymorphism. Through standard analyses, a north African mtDNA type that may have been imported previously from Spain or Portugal was not detected among neotropical African bees. Images PMID:1674608

  15. Does the mitochondrial transcription-termination complex play an essential role in controlling differential transcription of the mitochondrial DNA?

    PubMed

    Selwood, S P; Chrzanowska-Lightowlers, Z M; Lightowlers, R N

    2000-02-01

    The mechanism of mitochondrial transcription is well documented although the method of regulation remains obscure. The mitochondrial transcription-termination complex, mTERF, holds a key position in determining the fate of heavy-strand promotor-initiated transcripts and has been suggested as a candidate in the regulation of mitochondrial DNA (mtDNA) transcription. We report here the first example of a modulation of mTERF-complex binding activity concomitant with a differential mtDNA transcription rate. We suggest that these observations are indicative of a method of intra-organellar transcriptional fine tuning.

  16. Frequent somatic transfer of mitochondrial DNA into the nuclear genome of human cancer cells.

    PubMed

    Ju, Young Seok; Tubio, Jose M C; Mifsud, William; Fu, Beiyuan; Davies, Helen R; Ramakrishna, Manasa; Li, Yilong; Yates, Lucy; Gundem, Gunes; Tarpey, Patrick S; Behjati, Sam; Papaemmanuil, Elli; Martin, Sancha; Fullam, Anthony; Gerstung, Moritz; Nangalia, Jyoti; Green, Anthony R; Caldas, Carlos; Borg, Åke; Tutt, Andrew; Lee, Ming Ta Michael; van't Veer, Laura J; Tan, Benita K T; Aparicio, Samuel; Span, Paul N; Martens, John W M; Knappskog, Stian; Vincent-Salomon, Anne; Børresen-Dale, Anne-Lise; Eyfjörd, Jórunn Erla; Myklebost, Ola; Flanagan, Adrienne M; Foster, Christopher; Neal, David E; Cooper, Colin; Eeles, Rosalind; Bova, Steven G; Lakhani, Sunil R; Desmedt, Christine; Thomas, Gilles; Richardson, Andrea L; Purdie, Colin A; Thompson, Alastair M; McDermott, Ultan; Yang, Fengtang; Nik-Zainal, Serena; Campbell, Peter J; Stratton, Michael R

    2015-06-01

    Mitochondrial genomes are separated from the nuclear genome for most of the cell cycle by the nuclear double membrane, intervening cytoplasm, and the mitochondrial double membrane. Despite these physical barriers, we show that somatically acquired mitochondrial-nuclear genome fusion sequences are present in cancer cells. Most occur in conjunction with intranuclear genomic rearrangements, and the features of the fusion fragments indicate that nonhomologous end joining and/or replication-dependent DNA double-strand break repair are the dominant mechanisms involved. Remarkably, mitochondrial-nuclear genome fusions occur at a similar rate per base pair of DNA as interchromosomal nuclear rearrangements, indicating the presence of a high frequency of contact between mitochondrial and nuclear DNA in some somatic cells. Transmission of mitochondrial DNA to the nuclear genome occurs in neoplastically transformed cells, but we do not exclude the possibility that some mitochondrial-nuclear DNA fusions observed in cancer occurred years earlier in normal somatic cells.

  17. Frequent somatic transfer of mitochondrial DNA into the nuclear genome of human cancer cells

    PubMed Central

    Ju, Young Seok; Tubio, Jose M.C.; Mifsud, William; Fu, Beiyuan; Davies, Helen R.; Ramakrishna, Manasa; Li, Yilong; Yates, Lucy; Gundem, Gunes; Tarpey, Patrick S.; Behjati, Sam; Papaemmanuil, Elli; Martin, Sancha; Fullam, Anthony; Gerstung, Moritz; Nangalia, Jyoti; Green, Anthony R.; Caldas, Carlos; Borg, Åke; Tutt, Andrew; Lee, Ming Ta Michael; van't Veer, Laura J.; Tan, Benita K.T.; Aparicio, Samuel; Span, Paul N.; Martens, John W.M.; Knappskog, Stian; Vincent-Salomon, Anne; Børresen-Dale, Anne-Lise; Eyfjörd, Jórunn Erla; Flanagan, Adrienne M.; Foster, Christopher; Neal, David E.; Cooper, Colin; Eeles, Rosalind; Lakhani, Sunil R.; Desmedt, Christine; Thomas, Gilles; Richardson, Andrea L.; Purdie, Colin A.; Thompson, Alastair M.; McDermott, Ultan; Yang, Fengtang; Nik-Zainal, Serena; Campbell, Peter J.; Stratton, Michael R.

    2015-01-01

    Mitochondrial genomes are separated from the nuclear genome for most of the cell cycle by the nuclear double membrane, intervening cytoplasm, and the mitochondrial double membrane. Despite these physical barriers, we show that somatically acquired mitochondrial-nuclear genome fusion sequences are present in cancer cells. Most occur in conjunction with intranuclear genomic rearrangements, and the features of the fusion fragments indicate that nonhomologous end joining and/or replication-dependent DNA double-strand break repair are the dominant mechanisms involved. Remarkably, mitochondrial-nuclear genome fusions occur at a similar rate per base pair of DNA as interchromosomal nuclear rearrangements, indicating the presence of a high frequency of contact between mitochondrial and nuclear DNA in some somatic cells. Transmission of mitochondrial DNA to the nuclear genome occurs in neoplastically transformed cells, but we do not exclude the possibility that some mitochondrial-nuclear DNA fusions observed in cancer occurred years earlier in normal somatic cells. PMID:25963125

  18. Evidence for mitochondrial DNA polymorphism and uniparental inheritance in the cellular slime mold Polysphondylium pallidum: effect of intraspecies mating on mitochondrial DNA transmission.

    PubMed

    Mirfakhrai, M; Tanaka, Y; Yanagisawa, K

    1990-03-01

    Restriction fragment length polymorphisms (RFLPs) were used as markers to monitor mitochondrial inheritance in the cellular slime mold, Polysphondylium pallidum. When two opposite mating types (mat1 and mat2) of closely related strains were crossed, all the haploid progeny regardless of mating type inherited their mitochondrial DNA from the mat2 parent only. When opposite mating types from more distantly related strains were crossed, most of the progeny also inherited their mitochondrial DNA from the mat2 parent, but some inherited their mitochondrial DNA from the mat1 parent. In both cases however, the transmission of mitochondrial DNA was uniparental, since in every individual progeny only one type of mitochondrial DNA exists. Moreover, in crosses involving more distantly related strains all the progeny of a single macrocyst were shown to contain the same type of mitochondrial DNA. These findings are discussed in regard to mechanisms of transmission and the possible involvement of nuclear genes in the control of transmission of mitochondrial DNA in Polysphondylium.

  19. Assessment of the significance of mitochondrial DNA damage by chemotherapeutic agents.

    PubMed

    Lo, Soo; Tolner, Berend; Taanman, Jan-Willem; Cooper, J Mark; Gu, Mei; Hartley, John A; Schapira, Anthony H V; Hochhauser, Daniel

    2005-08-01

    The pathways which are activated following damage to nuclear DNA in cancer cells are well understood. There is evidence that treatment with several chemotherapeutic agents may result in damage to mitochondrial DNA. This study investigated the contribution of mitochondrial DNA to cytotoxicity of DNA-interactive agents. To understand the significance of drug interactions with mitochondrial DNA, we investigated A549 non-small cell lung cancer cell lines and their rho0 derivatives in which mitochondrial DNA has been eradicated. The parental cell line showed increased sensitivity to the anthracycline daunorubicin when compared with the A549 rho0 line. In addition, the A549 rho0 line was resistant to the rhodacyanine derivative, MKT-077, which has been shown to interact with mitochondrial DNA. Southern blotting demonstrated that MKT-077 mediated damage to mitochondrial but not nuclear DNA. Restoration of mitochondrial DNA by formation of cybrids restored sensitivity to these agents. The mitochondrial DNA damage, following treatment of A549 rho0 cells with MKT-077, resulted in G2 arrest which was not mediated by expression of p53. Mitochondrial DNA is a critical target for MKT-077 and daunorubicin, and is a potential target for novel chemotherapeutic agents.

  20. The mitochondrial permeability transition from yeast to mammals

    PubMed Central

    Azzolin, Luca; von Stockum, Sophia; Basso, Emy; Petronilli, Valeria; Forte, Michael A.; Bernardi, Paolo

    2010-01-01

    Regulated permeability changes have been detected in mitochondria across species. We review here their key features, with the goal of assessing whether a “permeability transition” similar to that observed in higher eukaryotes is present in other species. The recent discoveries (i) that treatment with cyclosporin A unmasks an inhibitory site for Pi [Basso et al. (2008) J. Biol Chem. 283, 26307–26311], the classical inhibitor of the permeability transition of yeast; and (ii) that under proper experimental conditions a matrix Ca2+-dependence can be demonstrated in yeast as well [Yamada et al. (2009) Biochim. Biophys. Acta 1787, 1486–1491] suggest that the mitochondrial permeability transition has been conserved during evolution. PMID:20398660

  1. Multiple mechanisms underlying troglitazone-induced mitochondrial permeability transition

    SciTech Connect

    Okuda, Takuya; Norioka, Misaki; Shitara, Yoshihisa; Horie, Toshiharu

    2010-11-01

    Troglitazone, a thiazolidinedione class antidiabetic drug, was withdrawn from the market because of its severe idiosyncratic hepatotoxicity. It causes a mitochondrial permeability transition (MPT), which may in part contribute to its hepatotoxicity. In the present study, the mechanism of troglitazone mitochondrial toxicity was investigated in isolated rat liver mitochondria. Mitochondrial swelling induced by 10 {mu}M troglitazone was attenuated by bromoenol lactone (BEL), an inhibitor of Ca{sup 2+}-independent phospholipase A{sub 2} (iPLA{sub 2}). In contrast, that induced by 50 {mu}M troglitazone was exacerbated by BEL. This exacerbation was diminished by addition of 2 mM glutathione, an antioxidant. Oxygen consumption by state 3 respiration in isolated mitochondria was also decreased by troglitazone, but it was not affected by BEL. Mitochondrial swelling induced by 10 {mu}M troglitazone was completely attenuated in the absence of Ca{sup 2+} while that induced by 50 {mu}M troglitazone was not affected. Addition of 1 {mu}M cyclosporin A (CsA), an inhibitor of MPT pores, completely attenuated swelling induced by 10 {mu}M troglitazone while it only partly diminished that induced by 50 {mu}M troglitazone. Thus, the MPT induced by 10 and 50 {mu}M troglitazone are regulated by different mechanism; the MPT induced by 10 {mu}M troglitazone is regulated by the activation of iPLA{sub 2} and caused by the opening of CsA-regulating MPT pores followed by accumulation of Ca{sup 2+} in mitochondria, while that induced by 50 {mu}M troglitazone is partly regulated by reactive oxygen species and mainly caused by the opening of CsA-insensitive MPT pores.

  2. Nucleation at the DNA supercoiling transition

    NASA Astrophysics Data System (ADS)

    Daniels, Bryan; Sethna, James

    2010-03-01

    When overtwisted, DNA forms the same wound coils that are familiar from phone cords and water hoses, creating coiled structures known as plectonemes. Experiments that twist single molecules of DNA have shown that the nucleation of plectonemes is thermally activated, with hopping near the supercoiling transition between states with and without a plectoneme. Theoretical estimates of the energy barrier of ˜6 kBT naively seem incompatible with the experimental rates of ˜ 1 Hz. Combining techniques from polymer physics and transition state theory, we use a dilute-gas path integral calculation to explain why the measured rate of hopping is so slow.

  3. Thermal adaptation and clinal mitochondrial DNA variation of European anchovy

    PubMed Central

    Silva, Gonçalo; Lima, Fernando P.; Martel, Paulo; Castilho, Rita

    2014-01-01

    Natural populations of widely distributed organisms often exhibit genetic clinal variation over their geographical ranges. The European anchovy, Engraulis encrasicolus, illustrates this by displaying a two-clade mitochondrial structure clinally arranged along the eastern Atlantic. One clade has low frequencies at higher latitudes, whereas the other has an anti-tropical distribution, with frequencies decreasing towards the tropics. The distribution pattern of these clades has been explained as a consequence of secondary contact after an ancient geographical isolation. However, it is not unlikely that selection acts on mitochondria whose genes are involved in relevant oxidative phosphorylation processes. In this study, we performed selection tests on a fragment of 1044 bp of the mitochondrial cytochrome b gene using 455 individuals from 18 locations. We also tested correlations of six environmental features: temperature, salinity, apparent oxygen utilization and nutrient concentrations of phosphate, nitrate and silicate, on a compilation of mitochondrial clade frequencies from 66 sampling sites comprising 2776 specimens from previously published studies. Positive selection in a single codon was detected predominantly (99%) in the anti-tropical clade and temperature was the most relevant environmental predictor, contributing with 59% of the variance in the geographical distribution of clade frequencies. These findings strongly suggest that temperature is shaping the contemporary distribution of mitochondrial DNA clade frequencies in the European anchovy. PMID:25143035

  4. Mitochondrial DNA sequence analysis of four Alzheimer`s and Parkinson`s disease patients

    SciTech Connect

    Brown, M.D.; Shoffner, J.M.; Wallace, D.C.

    1996-01-22

    The mitochondrial DNA (mtDNA) sequence was determined on 3 patients with Alzheimer`s disease (AD) exhibiting AD plus Parkinson`s disease (PD) neuropathologic changes and one patient with PD. Patient mtDNA sequences were compared to the standard Cambridge sequence to identify base changes. In the first AD + PD patient, 2 of the 15 nucleotide substitutions may contribute to the neuropathology, a nucleotide pair (np) 4336 transition in the tRNA{sup Gln} gene found 7.4 times more frequently in patients than in controls, and a unique np 721 transition in the 12S rRNA gene which was not found in 70 other patients or 905 controls. In the second AD + PD patient, 27 nucleotide substitutions were detected, including an np 3397 transition in the ND1 gene which converts a conserved methionine to a valine. In the third AD + PD patient, 2 polymorphic base substitutions frequently found at increased frequency in Leber`s hereditary optic neuropathy patients were observed, an np 4216 transition in ND1 and an np 13708 transition in the ND5 gene. For the PD patient, 2 novel variants were observed among 25 base substitutions, an np 1709 substitution in the 16S rRNA gene and an np 15851 missense mutation in the cytb gene. Further studies will be required to demonstrate a casual role for these base substitutions in neurodegenerative disease. 68 refs., 2 tabs.

  5. Mitochondrial Permeability Transition in Pathogenesis of Hemorrhagic Injury: Targeted Therapy with Minocycline

    DTIC Science & Technology

    2012-03-01

    minocy- cline treatment (Figures 1-4). Minocycline also improved mitochondrial function as assessed by intravital multiphoton imaging of the...will make direct measurements by intravital multiphoton microscopy to determine whether onset of the mitochondrial permeability transition and...oxidative stress were assessed 6 h after resuscitation. Mitochondrial polarization were assessed by intravital microscopy. After H/R with vehicle or

  6. Mitochondrial DNA phylogeography of least cisco Coregonus sardinella in Alaska.

    PubMed

    Padula, V M; Causey, D; López, J A

    2017-03-01

    This study presents the first detailed analysis of the mitochondrial DNA diversity of least cisco Coregonus sardinella in Alaska using a 678 bp segment of the control region (D-loop) of the mitochondrial genome. Findings suggest that the history of C. sardinella in Alaska differs from that of other species of Coregonus present in the state and surrounding regions. The examined populations of C. sardinella are genetically diverse across Alaska. Sixty-eight distinct mitochondrial haplotypes were identified among 305 individuals sampled from nine locations. The haplotype minimum spanning network and phylogeny showed a modest level of geographic segregation among haplotypes, suggesting high levels of on-going or recent connectivity among distant populations. Observed ΦST values and the results of homogeneity and AMOVAs indicate incipient genetic differentiation between aggregations in three broad regional groups. Sites north of the Brooks Range formed one group, sites in the Yukon and Selawik Rivers formed a second group and sites south of the Yukon drainage formed the third group. Overall, the sequence data showed that a large proportion of mtDNA genetic variation in C. sardinella is shared across Alaska, but this variation is not homogeneously distributed across all regions and for all haplotype groups. © 2017 The Fisheries Society of the British Isles.

  7. Mitochondrial DNA Copy Number Is Associated with Breast Cancer Risk

    PubMed Central

    Thyagarajan, Bharat; Wang, Renwei; Nelson, Heather; Barcelo, Helene; Koh, Woon-Puay; Yuan, Jian-Min

    2013-01-01

    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. PMID:23776581

  8. Modulating mitochondrial quality in disease transmission: towards enabling mitochondrial DNA disease carriers to have healthy children

    PubMed Central

    Diot, Alan; Dombi, Eszter; Lodge, Tiffany; Liao, Chunyan; Morten, Karl; Carver, Janet; Wells, Dagan; Child, Tim; Johnston, Iain G.; Williams, Suzannah; Poulton, Joanna

    2016-01-01

    One in 400 people has a maternally inherited mutation in mtDNA potentially causing incurable disease. In so-called heteroplasmic disease, mutant and normal mtDNA co-exist in the cells of carrier women. Disease severity depends on the proportion of inherited abnormal mtDNA molecules. Families who have had a child die of severe, maternally inherited mtDNA disease need reliable information on the risk of recurrence in future pregnancies. However, prenatal diagnosis and even estimates of risk are fraught with uncertainty because of the complex and stochastic dynamics of heteroplasmy. These complications include an mtDNA bottleneck, whereby hard-to-predict fluctuations in the proportions of mutant and normal mtDNA may arise between generations. In ‘mitochondrial replacement therapy’ (MRT), damaged mitochondria are replaced with healthy ones in early human development, using nuclear transfer. We are developing non-invasive alternatives, notably activating autophagy, a cellular quality control mechanism, in which damaged cellular components are engulfed by autophagosomes. This approach could be used in combination with MRT or with the regular management, pre-implantation genetic diagnosis (PGD). Mathematical theory, supported by recent experiments, suggests that this strategy may be fruitful in controlling heteroplasmy. Using mice that are transgenic for fluorescent LC3 (the hallmark of autophagy) we quantified autophagosomes in cleavage stage embryos. We confirmed that the autophagosome count peaks in four-cell embryos and this correlates with a drop in the mtDNA content of the whole embryo. This suggests removal by mitophagy (mitochondria-specific autophagy). We suggest that modulating heteroplasmy by activating mitophagy may be a useful complement to mitochondrial replacement therapy. PMID:27528757

  9. Modulating mitochondrial quality in disease transmission: towards enabling mitochondrial DNA disease carriers to have healthy children.

    PubMed

    Diot, Alan; Dombi, Eszter; Lodge, Tiffany; Liao, Chunyan; Morten, Karl; Carver, Janet; Wells, Dagan; Child, Tim; Johnston, Iain G; Williams, Suzannah; Poulton, Joanna

    2016-08-15

    One in 400 people has a maternally inherited mutation in mtDNA potentially causing incurable disease. In so-called heteroplasmic disease, mutant and normal mtDNA co-exist in the cells of carrier women. Disease severity depends on the proportion of inherited abnormal mtDNA molecules. Families who have had a child die of severe, maternally inherited mtDNA disease need reliable information on the risk of recurrence in future pregnancies. However, prenatal diagnosis and even estimates of risk are fraught with uncertainty because of the complex and stochastic dynamics of heteroplasmy. These complications include an mtDNA bottleneck, whereby hard-to-predict fluctuations in the proportions of mutant and normal mtDNA may arise between generations. In 'mitochondrial replacement therapy' (MRT), damaged mitochondria are replaced with healthy ones in early human development, using nuclear transfer. We are developing non-invasive alternatives, notably activating autophagy, a cellular quality control mechanism, in which damaged cellular components are engulfed by autophagosomes. This approach could be used in combination with MRT or with the regular management, pre-implantation genetic diagnosis (PGD). Mathematical theory, supported by recent experiments, suggests that this strategy may be fruitful in controlling heteroplasmy. Using mice that are transgenic for fluorescent LC3 (the hallmark of autophagy) we quantified autophagosomes in cleavage stage embryos. We confirmed that the autophagosome count peaks in four-cell embryos and this correlates with a drop in the mtDNA content of the whole embryo. This suggests removal by mitophagy (mitochondria-specific autophagy). We suggest that modulating heteroplasmy by activating mitophagy may be a useful complement to mitochondrial replacement therapy. © 2016 The Author(s).

  10. Evaluation of two mitochondrial DNA biomarkers for prostate cancer detection.

    PubMed

    Maragh, Samantha; Veltri, Robert W; Lund, Steven P; Mangold, Leslie; Isharwal, Sumit; Christudass, Christhunesa S; Partin, Alan W; Humphreys, Elizabeth B; Sorbara, Lynn; Srivastava, Sudhir; Wagner, Paul D

    2015-01-01

    A 3.4kb deletion (3.4kbΔ ) in mitochondrial DNA (mtDNA) found in histologically normal prostate biopsy specimens has been reported to be a biomarker for the increased probability of prostate cancer. Increased mtDNA copy number is also reported as associated with cancer. Independent evaluation of these two potential prostate cancer biomarkers using formalin-fixed paraffin-embedded (FFPE) prostate tissue and matched urine and serum from a high risk cohort of men with and without prostate cancer. Biomarker levels were detected via qPCR. Both 3.4kbΔ and mtDNA levels were significantly higher in cancer patient FFPE cores (p= 0.045 and p= 0.070 respectively at > 90% confidence). Urine from cancer patients contained significantly higher levels of mtDNA (p= 0.006, 64.3% sensitivity, 86.7% specificity). Combining the 3.4kbΔ and mtDNA gave better performance of detecting prostate cancer than either biomarker alone (FFPE 73.7% sensitivity, 65% specificity; urine 64.3% sensitivity, 100% specificity). In serum, there was no difference for any of the biomarkers. This is the first report on detecting the 3.4kbΔ in urine and evaluating mtDNA levels as a prostate cancer biomarker. A confirmation study with increased sample size and possibly with additional biomarkers would need to be conducted to corroborate and extend these observations.

  11. Mitochondrial DNA Sequence Analysis - Validation and Use for Forensic Casework.

    PubMed

    Holland, M M; Parsons, T J

    1999-06-01

    With the discovery of the polymerase chain reaction (PCR) in the mid-1980's, the last in a series of critical molecular biology techniques (to include the isolation of DNA from human and non-human biological material, and primary sequence analysis of DNA) had been developed to rapidly analyze minute quantities of mitochondrial DNA (mtDNA). This was especially true for mtDNA isolated from challenged sources, such as ancient or aged skeletal material and hair shafts. One of the beneficiaries of this work has been the forensic community. Over the last decade, a significant amount of research has been conducted to develop PCR-based sequencing assays for the mtDNA control region (CR), which have subsequently been used to further characterize the CR. As a result, the reliability of these assays has been investigated, the limitations of the procedures have been determined, and critical aspects of the analysis process have been identified, so that careful control and monitoring will provide the basis for reliable testing. With the application of these assays to forensic identification casework, mtDNA sequence analysis has been properly validated, and is a reliable procedure for the examination of biological evidence encountered in forensic criminalistic cases. Copyright © 1999 Central Police University.

  12. Mitochondrial DNA phylogeny in Eastern and Western Slavs.

    PubMed

    Malyarchuk, B; Grzybowski, T; Derenko, M; Perkova, M; Vanecek, T; Lazur, J; Gomolcak, P; Tsybovsky, I

    2008-08-01

    To resolve the phylogeny of certain mitochondrial DNA (mtDNA) haplogroups in eastern Europe and estimate their evolutionary age, a total of 73 samples representing mitochondrial haplogroups U4, HV*, and R1 were selected for complete mitochondrial genome sequencing from a collection of about 2,000 control region sequences sampled in eastern (Russians, Belorussians, and Ukrainians) and western (Poles, Czechs, and Slovaks) Slavs. On the basis of whole-genome resolution, we fully characterized a number of haplogroups (HV3, HV4, U4a1, U4a2, U4a3, U4b, U4c, U4d, and R1a) that were previously described only partially. Our findings demonstrate that haplogroups HV3, HV4, and U4a1 could be traced back to the pre-Neolithic times ( approximately 12,000-19,000 years before present [YBP]) in eastern Europe. In addition, an ancient connection between the Caucasus/Europe and India has been revealed by analysis of haplogroup R1 diversity, with a split between the Indian and Caucasus/European R1a lineages occurring about 16,500 years ago. Meanwhile, some mtDNA subgroups detected in Slavs (such as U4a2a, U4a2*, HV3a, and R1a1) are definitely younger being dated between 6,400 and 8,200 YBP. However, robust age estimations appear to be problematic due to the high ratios of nonsynonymous to synonymous substitutions found in young mtDNA subclusters.

  13. Bioenergetics of mitochondrial diseases associated with mtDNA mutations.

    PubMed

    Lenaz, Giorgio; Baracca, Alessandra; Carelli, Valerio; D'Aurelio, Marilena; Sgarbi, Gianluca; Solaini, Giancarlo

    2004-07-23

    This mini-review summarizes our present view of the biochemical alterations associated with mitochondrial DNA (mtDNA) point mutations. Mitochondrial cytopathies caused by mutations of mtDNA are well-known genetic and clinical entities, but the biochemical pathogenic mechanisms are often obscure. Leber's hereditary optic neuropathy (LHON) is due to three main mutations in genes for complex I subunits. Even if the catalytic activity of complex I is maintained except in cells carrying the 3460/ND1 mutation, in all cases there is a change in sensitivity to complex I inhibitors and an impairment of mitochondrial respiration, eliciting the possibility of generation of reactive oxygen species (ROS) by the complex. Neurogenic muscle weakness, Ataxia and Retinitis Pigmentosa (NARP), is due to a mutation in the ATPase-6 gene. In NARP patients ATP synthesis is strongly depressed to an extent proportional to the mutation load; nevertheless, ATP hydrolysis and ATP-driven proton translocation are not affected. It is suggested that the NARP mutation affects the ability of the enzyme to couple proton transport to ATP synthesis. A point mutation in subunit III of cytochrome c oxidase is accompanied by a syndrome resembling MELAS: however, no major biochemical defect is found, if we except an enhanced production of ROS. The mechanism of such enhancement is at present unknown. In this review, we draw attention to a few examples in which the overproduction of ROS might represent a common step in the induction of clinical phenotypes and/or in the progression of several human pathologies associated with mtDNA point mutations.

  14. Doxorubicin induces mitochondrial permeability transition and contractile dysfunction in the human myocardium.

    PubMed

    Montaigne, David; Marechal, Xavier; Preau, Sebastien; Baccouch, Riadh; Modine, Thomas; Fayad, George; Lancel, Steve; Neviere, Remi

    2011-01-01

    In human atrial trabeculae, we examined the effects of doxorubicin on the isometric force of contraction, mitochondrial respiration, membrane potential and calcium retention capacity. Compared with untreated controls, doxorubicin induced contractile dysfunction and depression of mitochondrial respiration. Mitochondria isolated from doxorubicin-treated human atrial trabeculae displayed reduced transmembrane potential and calcium retention capacity. Cyclosporine A, a mitochondrial membrane transition pore opening blocker, prevented mitochondrial dysfunction and impaired contractile performance induced by doxorubicin. The study suggests that a mitochondrial membrane transition pore opening is involved in the development of doxorubicin cardiotoxicity in human hearts. Copyright © 2010 Mitochondria Research Society. Published by Elsevier B.V. All rights reserved.

  15. Addressing RNA Integrity to Determine the Impact of Mitochondrial DNA Mutations on Brain Mitochondrial Function with Age

    PubMed Central

    Wang, Wei; Scheffler, Katja; Esbensen, Ying; Strand, Janne M.; Stewart, James B.; Bjørås, Magnar; Eide, Lars

    2014-01-01

    Mitochondrial DNA (mtDNA) mutations can result in mitochondrial dysfunction, but emerging experimental data question the fundamental role of mtDNA mutagenesis in age-associated mitochondrial impairment. The multicopy nature of mtDNA renders the impact of a given mtDNA mutation unpredictable. In this study, we compared mtDNA stability and mtRNA integrity during normal aging. Seven distinct sites in mouse brain mtDNA and corresponding mtRNA were analyzed. Accumulation of mtDNA mutations during aging was highly site-specific. The variation in mutation frequencies overrode the age-mediated increase by more than 100-fold and aging generally did not influence mtDNA mutagenesis. Errors introduced by mtRNA polymerase were also site-dependent and up to two hundred-fold more frequent than mtDNA mutations, and independent of mtDNA mutation frequency. We therefore conclude that mitochondrial transcription fidelity limits the impact of mtDNA mutations. PMID:24819950

  16. Addressing RNA integrity to determine the impact of mitochondrial DNA mutations on brain mitochondrial function with age.

    PubMed

    Wang, Wei; Scheffler, Katja; Esbensen, Ying; Strand, Janne M; Stewart, James B; Bjørås, Magnar; Eide, Lars

    2014-01-01

    Mitochondrial DNA (mtDNA) mutations can result in mitochondrial dysfunction, but emerging experimental data question the fundamental role of mtDNA mutagenesis in age-associated mitochondrial impairment. The multicopy nature of mtDNA renders the impact of a given mtDNA mutation unpredictable. In this study, we compared mtDNA stability and mtRNA integrity during normal aging. Seven distinct sites in mouse brain mtDNA and corresponding mtRNA were analyzed. Accumulation of mtDNA mutations during aging was highly site-specific. The variation in mutation frequencies overrode the age-mediated increase by more than 100-fold and aging generally did not influence mtDNA mutagenesis. Errors introduced by mtRNA polymerase were also site-dependent and up to two hundred-fold more frequent than mtDNA mutations, and independent of mtDNA mutation frequency. We therefore conclude that mitochondrial transcription fidelity limits the impact of mtDNA mutations.

  17. Rearrangements of mitochondrial DNA and the mitochondrial fusion-promoting plasmid (mF) are associated with defective mitochondrial fusion in Physarum polycephalum.

    PubMed

    Takano, H; Mori, K; Kawano, S; Kuroiwa, T

    1996-02-01

    A specific linear mitochondrial plasmid (mF) is genetically associated with the fusion of mitochondria in the true slime mould, Physarum polycephalum. In matings between mF+ and mF- strains, which respectively carry and do not carry the mF plasmid, mitochondrial fusion occurs in the zygote. Mitochondrial fusion induces recombination between specific sites in the mitochondrial DNA (mtDNA) and in the mF plasmid. To detect a region which is associated with the mitochondrial fusion in the mF plasmid, we isolated, by fluorescence microscopy, strains which showed defective mitochondrial fusion (delta mif-) from those which showed normal mitochondrial fusion (mif+). Analysis of the mitochondrial genomes of delta mif- strains showed only mtDNA which recombined with the mF plasmid in mitochondria. Comparison of this recombinant mtDNA in one delta mif- strain (NG 15) with that of a mif+ strain showed that a 2.2-kbp region, which included the integration site of the mF plasmid, was deleted in the delta mif- strain by recombination between the main mtDNA and the mF plasmid. In other strains, in addition to this deletion, a 6-kbp region which included both termini was deleted by recombination at six repeats of AAT sequences in the mF plasmid. Moreover, transcripts of the mF plasmid were not detected in NG15 by slot hybridization.

  18. Breeding populations of northern pintails have similar mitochondrial DNA

    USGS Publications Warehouse

    Cronin, M.A.; Grand, J.B.; Esler, Daniel; Derksen, D.V.; Scribner, K.T.

    1996-01-01

    Northern pintails (Anas acuta) are highly nomadic, which may result in high levels of gene flow among nesting areas. To assess the extent of genetic differentiation among nesting areas, we analyzed mitochondrial DNA (mtDNA) variation in northern pintail females from three regions: Alaska, California, and midcontinent prairies and parklands. Abundant mtDNA variation was evident (20 genotypes among 289 birds), but there was no significant genetic differentiation of nesting areas within or among regions. Results indicate that pintails have had historically large breeding population sizes and a high rate of gene flow among North American nesting areas. Specific nesting areas are not independent units, but part of a larger continental population. High rates of gene flow suggest that over time, localized reductions in recruitment or survival may be compensated for by immigration.

  19. NADH dehydrogenase subunit genes in the mitochondrial DNA of yeasts.

    PubMed Central

    Nosek, J; Fukuhara, H

    1994-01-01

    The genes encoding the NADH dehydrogenase subunits of respiratory complex I have not been identified so far in the mitochondrial DNA (mtDNA) of yeasts. In the linear mtDNA of Candida parapsilosis, we found six new open reading frames whose sequences were unambiguously homologous to those of the genes known to code for NADH dehydrogenase subunit proteins of different organisms, i.e., ND1, ND2, ND3, ND4L, ND5, and ND6. The gene for ND4 also appears to be present, as judged from hybridization experiments with a Podospora gene probe. Specific transcripts from these open reading frames (ND genes) could be detected in the mitochondria. Hybridization experiments using C. parapsilosis genes as probes suggested that ND genes are present in the mtDNAs of a wide range of yeast species including Candida catenulata, Pichia guilliermondii, Clavispora lusitaniae, Debaryomyces hansenii, Hansenula polymorpha, and others. Images PMID:7521869

  20. Mitochondrial and nuclear DNA damage induced by 5-aminolevulinic acid.

    PubMed

    Onuki, Janice; Chen, Yiming; Teixeira, Priscila C; Schumacher, Robert I; Medeiros, Marisa H G; Van Houten, Bennett; Di Mascio, Paolo

    2004-12-15

    5-Aminolevulinic acid (ALA) is a heme precursor accumulated in plasma and in organs in acute intermittent porphyria (AIP), a disease associated with neuromuscular dysfunction and increased incidence of hepatocellular carcinoma (HCC). Liver biopsies of AIP patients showed odd-shaped mitochondria and autophagic vacuoles containing well-preserved mitochondria. ALA yields reactive oxygen species upon metal-catalyzed oxidation and causes in vivo and in vitro impairment of rat liver mitochondria and DNA damage. Using a quantitative polymerase chain reaction assay, we demonstrated that ALA induces a dose-dependent damage in nuclear and mitochondrial DNA in human SVNF fibroblasts and rat PC12 cells. CHO cells treated with ALA also show nuclear DNA damage and human HepG2 cells entered in apoptosis and necrosis induced by ALA and its dimerization product, DHPY. The present data provide additional information on the genotoxicity of ALA, reinforcing the hypothesis that it may be involved in the development of HCC in AIP patients.

  1. 'Infertile' studies on mitochondrial DNA variation in asthenozoospermic Tunisian men.

    PubMed

    Salas, Antonio; Martinón-Torres, Federico; Gómez-Carballa, Alberto

    2016-12-01

    We reviewed five studies undertaken by the same research group on the possible links between mitochondrial DNA (mtDNA) variation and asthenozoospermia, all carried out on Tunisian men. A thorough assessment of these articles reveals that all five studies were carried out on virtually the same cohort of patients, although this information was concealed by the authors. Thus, the results were 'sliced' in order to unjustifiably maximize the number of publications. In addition, a phylogenetic analysis of their data indicates that the reported results are notably incomplete and deficient. Overall, contrary to the original claims, the association of mtDNA variants with asthenozoospermia finds no support on this saga on Tunisian infertile men.

  2. Forest elephant mitochondrial genomes reveal that elephantid diversification in Africa tracked climate transitions.

    PubMed

    Brandt, Adam L; Ishida, Yasuko; Georgiadis, Nicholas J; Roca, Alfred L

    2012-03-01

    Among elephants, the phylogeographic patterns of mitochondrial (mt) and nuclear markers are often incongruent. One hypothesis attributes this to sex differences in dispersal and in the variance of reproductive success. We tested this hypothesis by examining the coalescent dates of genetic markers within elephantid lineages, predicting that lower dispersal and lower variance in reproductive success among females would have increased mtDNA relative to nuclear coalescent dates. We sequenced the mitochondrial genomes of two forest elephants, aligning them to mitogenomes of African savanna and Asian elephants, and of woolly mammoths, including the most divergent mitogenomes within each lineage. Using fossil calibrations, the divergence between African elephant F and S clade mitochondrial genomes (originating in forest and savanna elephant lineages, respectively) was estimated as 5.5 Ma. We estimated that the (African) ancestor of the mammoth and Asian elephant lineages diverged 6.0 Ma, indicating that four elephantid lineages had differentiated in Africa by the Miocene-Pliocene transition, concurrent with drier climates. The coalescent date for forest elephant mtDNAs was c. 2.4 Ma, suggesting that the decrease in tropical forest cover during the Pleistocene isolated distinct African forest elephant lineages. For all elephantid lineages, the ratio of mtDNA to nuclear coalescent dates was much greater than 0.25. This is consistent with the expectation that sex differences in dispersal and in variance of reproductive success would have increased the effective population size of mtDNA relative to nuclear markers in elephantids, contributing to the persistence of incongruent mtDNA phylogeographic patterns.

  3. Arsenic trioxide promotes mitochondrial DNA mutation and cell apoptosis in primary APL cells and NB4 cell line.

    PubMed

    Meng, Ran; Zhou, Jin; Sui, Meng; Li, ZhiYong; Feng, GuoSheng; Yang, BaoFeng

    2010-01-01

    This study aimed to investigate the effects of arsenic trioxide (As(2)O(3)) on the mitochondrial DNA (mtDNA) of acute promyelocytic leukemia (APL) cells. The NB4 cell line was treated with 2.0 micromol/L As(2)O(3) in vitro, and the primary APL cells were treated with 2.0 micromol/L As(2)O(3) in vitro and 0.16 mg kg(-1) d(-1) As(2)O(3) in vivo. The mitochondrial DNA of all the cells above was amplified by PCR, directly sequenced and analyzed by Sequence Navigatore and Factura software. The apoptosis rates were assayed by flow cytometry. Mitochondrial DNA mutation in the D-loop region was found in NB4 and APL cells before As(2)O(3) use, but the mutation spots were remarkably increased after As(2)O(3) treatment, which was positively correlated to the rates of cellular apoptosis, the correlation coefficient: r (NB4-As2O3)=0.973818, and r (APL-As2O3)=0.934703. The mutation types include transition, transversion, codon insertion or deletion, and the mutation spots in all samples were not constant and regular. It is revealed that As(2)O(3) aggravates mtDNA mutation in the D-loop region of acute promyelocytic leukemia cells both in vitro and in vivo. Mitochondrial DNA might be one of the targets of As(2)O(3) in APL treatment.

  4. Mitochondrial DNA data reveal cryptic species within Taenia krabbei.

    PubMed

    Lavikainen, Antti; Haukisalmi, Voitto; Lehtinen, Markus J; Laaksonen, Sauli; Holmström, Sauli; Isomursu, Marja; Oksanen, Antti; Meri, Seppo

    2010-06-01

    Cysticerci of Taenia sp. from two elks (Alces alces) in Finland were characterized using morphological criteria and sequences of two mitochondrial DNA regions. The host species, size, structure and location of the cysticerci indicated that they might belong to Taenia krabbei, a circumpolar species occurring in a sylvatic life cycle in wild canids and cervids. Based on the number, length and shape of the rostellar hooks, the specimens could not be unambiguously defined as belonging to T. krabbei, T. cervi, T. ovis or T. solium. In the phylogenetic analysis, based on mitochondrial nucleotide sequence data, Taenia sp. was placed as a sister species of T. solium, distant from T. krabbei isolates previously characterized from Svalbard. This indicates that the Finnish and the Svalbard isolates, resembling T. krabbei, cannot represent a single species. The results suggest that careful morphological and genetic analyses of further isolates from intermediate and definitive hosts are required to define the taxonomic status of these two cryptic species.

  5. Genetic deletion of the mitochondrial phosphate carrier desensitizes the mitochondrial permeability transition pore and causes cardiomyopathy.

    PubMed

    Kwong, J Q; Davis, J; Baines, C P; Sargent, M A; Karch, J; Wang, X; Huang, T; Molkentin, J D

    2014-08-01

    The mitochondrial phosphate carrier (PiC) is critical for ATP synthesis by serving as the primary means for mitochondrial phosphate import across the inner membrane. In addition to its role in energy production, PiC is hypothesized to have a role in cell death as either a component or a regulator of the mitochondrial permeability transition pore (MPTP) complex. Here, we have generated a mouse model with inducible and cardiac-specific deletion of the Slc25a3 gene (PiC protein). Loss of PiC protein did not prevent MPTP opening, suggesting it is not a direct pore-forming component of this complex. However, Slc25a3 deletion in the heart blunted MPTP opening in response to Ca(2+) challenge and led to a greater Ca(2+) uptake capacity. This desensitization of MPTP opening due to loss or reduction in PiC protein attenuated cardiac ischemic-reperfusion injury, as well as partially protected cells in culture from Ca(2+) overload induced death. Intriguingly, deletion of the Slc25a3 gene from the heart long-term resulted in profound hypertrophy with ventricular dilation and depressed cardiac function, all features that reflect the cardiomyopathy observed in humans with mutations in SLC25A3. Together, these results demonstrate that although the PiC is not a direct component of the MPTP, it can regulate its activity, suggesting a novel therapeutic target for reducing necrotic cell death. In addition, mice lacking Slc25a3 in the heart serve as a novel model of metabolic, mitochondrial-driven cardiomyopathy.

  6. Mitochondrial DNA copy numbers in pyramidal neurons are decreased and mitochondrial biogenesis transcriptome signaling is disrupted in Alzheimer's disease hippocampi.

    PubMed

    Rice, Ann C; Keeney, Paula M; Algarzae, Norah K; Ladd, Amy C; Thomas, Ravindar R; Bennett, James P

    2014-01-01

    Alzheimer's disease (AD) is the major cause of adult-onset dementia and is characterized in its pre-diagnostic stage by reduced cerebral cortical glucose metabolism and in later stages by reduced cortical oxygen uptake, implying reduced mitochondrial respiration. Using quantitative PCR we determined the mitochondrial DNA (mtDNA) gene copy numbers from multiple groups of 15 or 20 pyramidal neurons, GFAP(+) astrocytes and dentate granule neurons isolated using laser capture microdissection, and the relative expression of mitochondrial biogenesis (mitobiogenesis) genes in hippocampi from 10 AD and 9 control (CTL) cases. AD pyramidal but not dentate granule neurons had significantly reduced mtDNA copy numbers compared to CTL neurons. Pyramidal neuron mtDNA copy numbers in CTL, but not AD, positively correlated with cDNA levels of multiple mitobiogenesis genes. In CTL, but not in AD, hippocampal cDNA levels of PGC1α were positively correlated with multiple downstream mitobiogenesis factors. Mitochondrial DNA copy numbers in pyramidal neurons did not correlate with hippocampal Aβ1-42 levels. After 48 h exposure of H9 human neural stem cells to the neurotoxic fragment Aβ25-35, mtDNA copy numbers were not significantly altered. In summary, AD postmortem hippocampal pyramidal neurons have reduced mtDNA copy numbers. Mitochondrial biogenesis pathway signaling relationships are disrupted in AD, but are mostly preserved in CTL. Our findings implicate complex alterations of mitochondria-host cell relationships in AD.

  7. Low abundance of mitochondrial DNA changes mitochondrial status and renders cells resistant to serum starvation and sodium nitroprusside insult.

    PubMed

    Lee, Sung Ryul; Heo, Hye Jin; Jeong, Seung Hun; Kim, Hyoung Kyu; Song, In Sung; Ko, Kyung Soo; Rhee, Byoung Doo; Kim, Nari; Han, Jin

    2015-07-01

    Mutation or depletion of mitochondrial DNA (mtDNA) can cause severe mitochondrial malfunction, originating from the mitochondrion itself, or from the crosstalk between nuclei and mitochondria. However, the changes that would occur if the amount of mtDNA is diminished are less known. Thus, we generated rat myoblast H9c2 cells containing lower amounts of mtDNA via ethidium bromide and uridine supplementation. After confirming the depletion of mtDNA by quantitative PCR and gel electrophoresis analysis, we investigated the changes in mitochondrial physical parameters by using flow cytometry. We also evaluated the resistance of these cells to serum starvation and sodium nitroprusside. H9c2 cells with diminished mtDNA contents showed decreased mitochondrial membrane potential, mass, free calcium, and zinc ion contents as compared to naïve H9c2 cells. Furthermore, cytosolic and mitochondrial reactive oxygen species levels were significantly higher in mtDNA-lowered H9c2 cells than in the naïve cells. Although the oxygen consumption rate and cell proliferation were decreased, mtDNA-lowered H9c2 cells were more resistant to serum deprivation and nitroprusside insults than the naïve H9c2 cells. Taken together, we conclude that the low abundance of mtDNA cause changes in cellular status, such as changes in reactive oxygen species, calcium, and zinc ion levels inducing resistance to stress.

  8. Typing single polymorphic nucleotides in mitochondrial DNA as a way to access Middle Pleistocene DNA

    PubMed Central

    Valdiosera, Cristina; García, Nuria; Dalén, Love; Smith, Colin; Kahlke, Ralf-Dietrich; Lidén, Kerstin; Angerbjörn, Anders; Arsuaga, Juan Luis; Götherström, Anders

    2006-01-01

    In this study, we have used a technique designed to target short fragments containing informative mitochondrial substitutions to extend the temporal limits of DNA recovery and study the molecular phylogeny of Ursus deningeri. We present a cladistic analysis using DNA recovered from 400 kyr old U. deningeri remains, which demonstrates U. deningeri's relation to Ursus spelaeus. This study extends the limits of recovery from skeletal remains by almost 300 kyr. Plant material from permafrost environments has yielded DNA of this age in earlier studies, and our data suggest that DNA in teeth from cave environments may be equally well preserved. PMID:17148299

  9. Bnip3-mediated mitochondrial autophagy is independent of the mitochondrial permeability transition pore

    PubMed Central

    Quinsay, Melissa N; Thomas, Robert L; Lee, Youngil

    2010-01-01

    Bnip3 is a pro-apoptotic BH3-only protein which is associated with mitochondrial dysfunction and cell death. Bnip3 is also a potent inducer of autophagy in many cells. In this study, we have investigated the mechanism by which Bnip3 induces autophagy in adult cardiac myocytes. Overexpression of Bnip3 induced extensive autophagy in adult cardiac myocytes. Fluorescent microscopy studies and ultrastructural analysis revealed selective degradation of mitochondria by autophagy in myocytes overexpressing Bnip3. Oxidative stress and increased levels of intracellular Ca2+ have been reported by others to induce autophagy, but Bnip3-induced autophagy was not abolished by antioxidant treatment or the Ca2+ chelator BAPTA-AM. We also investigated the role of the mitochondrial permeability transition pore (mPTP) in Bnip3-induced autophagy. Although the mPTP has previously been implicated in the induction of autophagy and selective removal of damaged mitochondria by autophagosomes, mitochondria sequestered by autophagosomes in Bnip3-treated cardiac myocytes had not undergone permeability transition and treatment with the mPTP inhibitor cyclosporine A did not inhibit mitochondrial autophagy in cardiac myocytes. Moreover, cyclophilin D (cypD) is an essential component of the mPTP and Bnip3 induced autophagy to the same extent in embryonic fibroblasts isolated from wild-type and cypD-deficient mice. These results support a model where Bnip3 induces selective removal of the mitochondria in cardiac myocytes and that Bnip3 triggers induction of autophagy independent of Ca2+, ROS generation and mPTP opening. PMID:20668412

  10. Mitochondrial DNA integrity is not dependent on DNA polymerase-beta activity.

    PubMed

    Hansen, Alexis B; Griner, Nicholas B; Anderson, Jon P; Kujoth, Greg C; Prolla, Tomas A; Loeb, Lawrence A; Glick, Eitan

    2006-01-05

    Mutations in mitochondrial DNA (mtDNA) are involved in a variety of pathologies, including cancer and neurodegenerative diseases, as well as in aging. mtDNA mutations result predominantly from damage by reactive oxygen species (ROS) that is not repaired prior to replication. Repair of ROS-damaged bases occurs mainly via base excision repair (BER) in mitochondria and nuclei. In nuclear BER, the two penultimate steps are carried out by DNA polymerase-beta (Polbeta), which exhibits both 5'-deoxyribose-5-phosphate (5'-dRP) lyase and DNA polymerase activities. In mitochondria, DNA polymerase-gamma (Polgamma) is believed to be the sole polymerase and is therefore assumed to function in mitochondrial BER. However, a recent report suggested the presence of Polbeta or a "Polbeta-like" enzyme in bovine mitochondria. Consequently, in the present work, we tested the hypothesis that Polbeta is present and functions in mammalian mitochondria. Initially we identified two DNA polymerase activities, one corresponding to Polgamma and the other to Polbeta, in mitochondrial preparations obtained by differential centrifugation and discontinuous sucrose density gradient centrifugation. However, upon further fractionation in linear Percoll gradients, we were able to separate Polbeta from mitochondria and to show that intact mitochondria, identified by electron microscopy, lacked Polbeta activity. In a functional test for the presence of Polbeta function in mitochondria, we used a new assay for detection of random (i.e., non-clonal) mutations in single mtDNA molecules. We did not detect enhanced mutation frequency in mtDNA from Polbeta null cells. In contrast, mtDNA from cells harboring mutations in the Polgamma exonuclease domain that abolish proofreading displayed a >or=17-fold increase in mutation frequency. We conclude that Polbeta is not an essential component of the machinery that maintains mtDNA integrity.

  11. Mitochondrial DNA Copy Number and Exposure to Polycyclic Aromatic Hydrocarbons

    PubMed Central

    Pavanello, Sofia; Dioni, Laura; Hoxha, Mirjam; Fedeli, Ugo; Mielzynska-Švach, Danuta; Baccarelli, Andrea A.

    2013-01-01

    Background Increased mitochondrial DNA copy number (mtDNAcn) is a biological response to mtDNA damage and dysfunction predictive of lung cancer risk. Polycyclic aromatic hydrocarbons (PAHs) are established lung carcinogens and may cause mitochondrial toxicity. Whether PAH exposure and PAH-related nuclear DNA (nDNA) genotoxic effects are linked with increased mtDNAcn has never been evaluated. Methods We investigated the effect of chronic exposure to PAHs on mtDNAcn in peripheral blood lymphocytes (PBLs) of 46 Polish male non-current smoking cokeoven workers and 44 matched controls, who were part of a group of 94 study individuals examined in our previous work. Subjects PAH exposure and genetic alterations were characterized through measures of internal dose (urinary 1-pyrenol), target dose [anti-benzo[a]pyrene diolepoxide (anti-BPDE)-DNA adduct], genetic instability (micronuclei, MN and telomere length [TL]) and DNA methylation [p53 promoter] in PBLs. mtDNAcn (MT/S) was measured using a validated real-time PCR method. Results Workers with PAH exposure above the median value (>3 µmol 1-pyrenol/mol creatinine) showed higher mtDNAcn [geometric means (GM) of 1.06 (unadjusted) and 1.07 (age-adjusted)] compared to controls [GM 0.89 (unadjusted); 0.89 (age-adjusted)] (p=0.029 and 0.016), as well as higher levels of genetic and chromosomal [i.e. anti-BPDE-DNA adducts (p<0.001), MN (p<0.001) and TL (p=0.053)] and epigenetic [i.e., p53 gene-specific promoter methylation (p<0.001)] alterations in the nDNA. In the whole study population, unadjusted and age-adjusted mtDNAcn was positively correlated with 1-pyrenol (p=0.043 and 0.032) and anti-BPDE-DNA adducts (p=0.046 and 0.049). Conclusions PAH exposure and PAH-related nDNA genotoxicity are associated with increased mtDNAcn. Impact The present study is suggestive of potential roles of mtDNAcn in PAH-induced carcinogenesis. PMID:23885040

  12. Mitochondrial DNA lineages of Italian Giara and Sarcidano horses.

    PubMed

    Morelli, L; Useli, A; Sanna, D; Barbato, M; Contu, D; Pala, M; Cancedda, M; Francalacci, P

    2014-10-20

    Giara and Sarcidano are 2 of the 15 extant native Italian horse breeds with limited dispersal capability that originated from a larger number of individuals. The 2 breeds live in two distinct isolated locations on the island of Sardinia. To determine the genetic structure and evolutionary history of these 2 Sardinian breeds, the first hypervariable segment of the mitochondrial DNA (mtDNA) was sequenced and analyzed in 40 Giara and Sarcidano horses and compared with publicly available mtDNA data from 43 Old World breeds. Four different analyses, including genetic distance, analysis of molecular variance, haplotype sharing, and clustering methods, were used to study the genetic relationships between the Sardinian and other horse breeds. The analyses yielded similar results, and the FST values indicated that a high percentage of the total genetic variation was explained by between-breed differences. Consistent with their distinct phenotypes and geographic isolation, the two Sardinian breeds were shown to consist of 2 distinct gene pools that had no gene flow between them. Giara horses were clearly separated from the other breeds examined and showed traces of ancient separation from horses of other breeds that share the same mitochondrial lineage. On the other hand, the data from the Sarcidano horses fit well with variation among breeds from the Iberian Peninsula and North-West Europe: genetic relationships among Sarcidano and the other breeds are consistent with the documented history of this breed.

  13. Reconstructing ancient mitochondrial DNA links between Africa and Europe

    PubMed Central

    Cerezo, María; Achilli, Alessandro; Olivieri, Anna; Perego, Ugo A.; Gómez-Carballa, Alberto; Brisighelli, Francesca; Lancioni, Hovirag; Woodward, Scott R.; López-Soto, Manuel; Carracedo, Ángel; Capelli, Cristian; Torroni, Antonio; Salas, Antonio

    2012-01-01

    Mitochondrial DNA (mtDNA) lineages of macro-haplogroup L (excluding the derived L3 branches M and N) represent the majority of the typical sub-Saharan mtDNA variability. In Europe, these mtDNAs account for <1% of the total but, when analyzed at the level of control region, they show no signals of having evolved within the European continent, an observation that is compatible with a recent arrival from the African continent. To further evaluate this issue, we analyzed 69 mitochondrial genomes belonging to various L sublineages from a wide range of European populations. Phylogeographic analyses showed that ∼65% of the European L lineages most likely arrived in rather recent historical times, including the Romanization period, the Arab conquest of the Iberian Peninsula and Sicily, and during the period of the Atlantic slave trade. However, the remaining 35% of L mtDNAs form European-specific subclades, revealing that there was gene flow from sub-Saharan Africa toward Europe as early as 11,000 yr ago. PMID:22454235

  14. Transition state for protein-DNA recognition.

    PubMed

    Ferreiro, Diego U; Sánchez, Ignacio E; de Prat Gay, Gonzalo

    2008-08-05

    We describe the formation of protein-DNA contacts in the two-state route for DNA sequence recognition by a transcriptional regulator. Surprisingly, direct sequence readout establishes in the transition state and constitutes the bottleneck of complex formation. Although a few nonspecific ionic interactions are formed at this early stage, they mainly play a stabilizing role in the final consolidated complex. The interface is fairly plastic in the transition state, likely because of a high level of hydration. The overall picture of this two-state route largely agrees with a smooth energy landscape for binding that speeds up DNA recognition. This "direct" two-state route differs from the parallel multistep pathway described for this system, which involves nonspecific contacts and at least two intermediate species that must involve substantial conformational rearrangement in either or both macromolecules.

  15. Nuclear and mitochondrial DNA sequences from two Denisovan individuals

    PubMed Central

    Sawyer, Susanna; Renaud, Gabriel; Viola, Bence; Hublin, Jean-Jacques; Gansauge, Marie-Theres; Shunkov, Michael V.; Derevianko, Anatoly P.; Prüfer, Kay; Pääbo, Svante

    2015-01-01

    Denisovans, a sister group of Neandertals, have been described on the basis of a nuclear genome sequence from a finger phalanx (Denisova 3) found in Denisova Cave in the Altai Mountains. The only other Denisovan specimen described to date is a molar (Denisova 4) found at the same site. This tooth carries a mtDNA sequence similar to that of Denisova 3. Here we present nuclear DNA sequences from Denisova 4 and a morphological description, as well as mitochondrial and nuclear DNA sequence data, from another molar (Denisova 8) found in Denisova Cave in 2010. This new molar is similar to Denisova 4 in being very large and lacking traits typical of Neandertals and modern humans. Nuclear DNA sequences from the two molars form a clade with Denisova 3. The mtDNA of Denisova 8 is more diverged and has accumulated fewer substitutions than the mtDNAs of the other two specimens, suggesting Denisovans were present in the region over an extended period. The nuclear DNA sequence diversity among the three Denisovans is comparable to that among six Neandertals, but lower than that among present-day humans. PMID:26630009

  16. Mitochondrial DNA deletion analysis: a comparison of PCR quantitative methods.

    PubMed

    Hamblet, N S; Castora, F J

    1995-02-15

    The role of mitochondrial DNA (mtDNA) deletions in aging and in neurodegenerative diseases is often determined by measuring the amount of deleted mtDNA in the affected tissue. Upon examining brain autopsy tissue from a 59 year old individual with lung cancer we determined by serial dilution PCR and kinetic PCR that a greater ratio of deleted mtDNA was present in the caudate than in the parietal cortex. However, the magnitude difference for these two brain regions appeared to be technique dependent; by serial dilution PCR the caudate had 10 times more deleted mtDNA than the parietal cortex (0.0141 vs 0.0014) whereas kinetic PCR yielded a 4-fold difference (0.1258 vs 0.0316). These results indicate that although it is valid to compare the amount of deleted mtDNA in normal and diseased tissue and draw conclusions based on relative comparisons within one study, greater caution should be exercised when comparing absolute values from studies using different measurement techniques.

  17. Sperm mitochondrial DNA deletion in Iranian infertiles with asthenozoospermia.

    PubMed

    Bahrehmand Namaghi, I; Vaziri, H

    2017-04-01

    Asthenozoospermia is an important cause of male infertility. The mutations in sperm mitochondrial DNA (mtDNA) result in either functionless or malfunctioning some proteins, subsequently affecting sperm motility leading to asthenozoospermia. The purpose of this study was to investigate sperm mtDNA 4,977-bp deletion in infertile men with low sperm motility/immotile spermatozoa compared to healthy subjects with high sperm motility. Semen samples of 256 asthenozoospermic infertiles and 200 controls from northern Iran were collected. After extraction of spermatozoa total DNA, Gap-polymerase chain reaction (Gap-PCR) was performed. The deletion was observed in 85.93% of patients with asthenozoospermia compared with 14% in controls [OR = 37.5397, 95% confidence interval = 12.937-108.9276, p < .0001]. It is concluded that there is a strong association between sperm mtDNA 4,977-bp deletion and asthenozoospermia-induced infertility in the population examined. Large-scale mtDNA deletions in spermatozoa may induce bioenergetic disorders. Nevertheless, to validate our results broader research may be needed.

  18. Historically low mitochondrial DNA diversity in koalas (Phascolarctos cinereus)

    PubMed Central

    2012-01-01

    Background The koala (Phascolarctos cinereus) is an arboreal marsupial that was historically widespread across eastern Australia until the end of the 19th century when it suffered a steep population decline. Hunting for the fur trade, habitat conversion, and disease contributed to a precipitous reduction in koala population size during the late 1800s and early 1900s. To examine the effects of these reductions in population size on koala genetic diversity, we sequenced part of the hypervariable region of mitochondrial DNA (mtDNA) in koala museum specimens collected in the 19th and 20th centuries, hypothesizing that the historical samples would exhibit greater genetic diversity. Results The mtDNA haplotypes present in historical museum samples were identical to haplotypes found in modern koala populations, and no novel haplotypes were detected. Rarefaction analyses suggested that the mtDNA genetic diversity present in the museum samples was similar to that of modern koalas. Conclusions Low mtDNA diversity may have been present in koala populations prior to recent population declines. When considering management strategies, low genetic diversity of the mtDNA hypervariable region may not indicate recent inbreeding or founder events but may reflect an older historical pattern for koalas. PMID:23095716

  19. Historically low mitochondrial DNA diversity in koalas (Phascolarctos cinereus).

    PubMed

    Tsangaras, Kyriakos; Ávila-Arcos, María C; Ishida, Yasuko; Helgen, Kristofer M; Roca, Alfred L; Greenwood, Alex D

    2012-10-24

    The koala (Phascolarctos cinereus) is an arboreal marsupial that was historically widespread across eastern Australia until the end of the 19th century when it suffered a steep population decline. Hunting for the fur trade, habitat conversion, and disease contributed to a precipitous reduction in koala population size during the late 1800s and early 1900s. To examine the effects of these reductions in population size on koala genetic diversity, we sequenced part of the hypervariable region of mitochondrial DNA (mtDNA) in koala museum specimens collected in the 19th and 20th centuries, hypothesizing that the historical samples would exhibit greater genetic diversity. The mtDNA haplotypes present in historical museum samples were identical to haplotypes found in modern koala populations, and no novel haplotypes were detected. Rarefaction analyses suggested that the mtDNA genetic diversity present in the museum samples was similar to that of modern koalas. Low mtDNA diversity may have been present in koala populations prior to recent population declines. When considering management strategies, low genetic diversity of the mtDNA hypervariable region may not indicate recent inbreeding or founder events but may reflect an older historical pattern for koalas.

  20. Homogeneity in mitochondrial DNA control region sequences in Swedish subpopulations.

    PubMed

    Tillmar, Andreas O; Coble, Michael D; Wallerström, Thomas; Holmlund, Gunilla

    2010-03-01

    In order to promote mitochondrial DNA (mtDNA) testing in Sweden we have typed 296 Swedish males, which will serve as a Swedish mtDNA frequency database. The tested males were taken from seven geographically different regions representing the contemporary Swedish population. The complete mtDNA control region was typed and the Swedish population was shown to have high haplotype diversity with a random match probability of 0.5%. Almost 47% of the tested samples belonged to haplogroup H and further haplogroup comparison with worldwide populations clustered the Swedish mtDNA data together with other European populations. AMOVA analysis of the seven Swedish subregions displayed no significant maternal substructure in Sweden (F (ST) = 0.002). Our conclusion from this study is that the typed Swedish individuals serve as good representatives for a Swedish forensic mtDNA database. Some caution should, however, be taken for individuals from the northernmost part of Sweden (provinces of Norrbotten and Lapland) due to specific demographic conditions. Furthermore, our analysis of a small sample set of a Swedish Saami population confirmed earlier findings that the Swedish Saami population is an outlier among European populations.

  1. Mesencephalic complex I deficiency does not correlate with parkinsonism in mitochondrial DNA maintenance disorders.

    PubMed

    Palin, Eino J H; Paetau, Anders; Suomalainen, Anu

    2013-08-01

    Genetic evidence from recessively inherited Parkinson's disease has indicated a clear causative role for mitochondrial dysfunction in Parkinson's disease. This role has long been discussed based on findings that toxic inhibition of mitochondrial respiratory complex I caused parkinsonism and that tissues of patients with Parkinson's disease show complex I deficiency. Disorders of mitochondrial DNA maintenance are a common cause of inherited neurodegenerative disorders, and lead to mitochondrial DNA deletions or depletion and respiratory chain defect, including complex I deficiency. However, parkinsonism associates typically with defects of catalytic domain of mitochondrial DNA polymerase gamma. Surprisingly, however, not all mutations affecting DNA polymerase gamma manifest as parkinsonism, but, for example, spacer region mutations lead to spinocerebellar ataxia and/or severe epilepsy. Furthermore, defective Twinkle helicase, a close functional companion of DNA polymerase gamma in mitochondrial DNA replication, results in infantile-onset spinocerebellar ataxia, epilepsy or adult-onset mitochondrial myopathy, but not typically parkinsonism. Here we sought for clues for this specificity in the neurological manifestations of mitochondrial DNA maintenance disorders by studying mesencephalic neuropathology of patients with DNA polymerase gamma or Twinkle defects, with or without parkinsonism. We show here that all patients with mitochondrial DNA maintenance disorders had neuronopathy in substantia nigra, most severe in DNA polymerase gamma-associated parkinsonism. The oculomotor nucleus was also affected, but less severely. In substantia nigra, all patients had a considerable decrease of respiratory chain complex I, but other respiratory chain enzymes were not affected. Complex I deficiency did not correlate with parkinsonism, age, affected gene or inheritance. We conclude that the cell number in substantia nigra correlated well with parkinsonism in DNA polymerase gamma

  2. Amerindian mitochondrial DNA haplogroups predominate in the population of Argentina: towards a first nationwide forensic mitochondrial DNA sequence database.

    PubMed

    Bobillo, Maria Cecilia; Zimmermann, Bettina; Sala, Andrea; Huber, Gabriela; Röck, Alexander; Bandelt, Hans-Jürgen; Corach, Daniel; Parson, Walther

    2010-07-01

    The study presents South American mitochondrial DNA (mtDNA) data from selected north (N = 98), central (N = 193) and south (N = 47) Argentinean populations. Sequence analysis of the complete mtDNA control region (CR, 16024-576) resulted in 288 unique haplotypes ignoring C-insertions around positions 16193, 309, and 573; the additional analysis of coding region single nucleotide polymorphisms enabled a fine classification of the described lineages. The Amerindian haplogroups were most frequent in the north and south representing more than 60% of the sequences. A slightly different situation was observed in central Argentina where the Amerindian haplogroups represented less than 50%, and the European contribution was more relevant. Particular clades of the Amerindian subhaplogroups turned out to be nearly region-specific. A minor contribution of African lineages was observed throughout the country. This comprehensive admixture of worldwide mtDNA lineages and the regional specificity of certain clades in the Argentinean population underscore the necessity of carefully selecting regional samples in order to develop a nationwide mtDNA database for forensic and anthropological purposes. The mtDNA sequencing and analysis were performed under EMPOP guidelines in order to attain high quality for the mtDNA database.

  3. Association Between Chloroplast DNA and Mitochondrial DNA Haplotypes in Prunus spinosa L. (Rosaceae) Populations across Europe

    PubMed Central

    MOHANTY, APARAJITA; MARTÍN, JUAN PEDRO; GONZÁLEZ, LUIS MIGUEL; AGUINAGALDE, ITZIAR

    2003-01-01

    Chloroplast DNA (cpDNA) and mitochondrial DNA (mtDNA) were studied in 24 populations of Prunus spinosa sampled across Europe. The cpDNA and mtDNA fragments were amplified using universal primers and subsequently digested with restriction enzymes to obtain the polymorphisms. Combinations of all the polymorphisms resulted in 33 cpDNA haplotypes and two mtDNA haplotypes. Strict association between the cpDNA haplotypes and the mtDNA haplotypes was detected in most cases, indicating conjoint inheritance of the two genomes. The most frequent and abundant cpDNA haplotype (C20; frequency, 51 %) is always associated with the more frequent and abundant mtDNA haplotype (M1; frequency, 84 %). All but two of the cpDNA haplotypes associated with the less frequent mtDNA haplotype (M2) are private haplotypes. These private haplotypes are phylogenetically related but geographically unrelated. They form a separate cluster on the minimum‐length spanning tree. PMID:14534199

  4. Association Between Mitochondrial DNA Haplogroup and Myelodysplastic Syndromes

    PubMed Central

    Poynter, Jenny N.; Richardson, Michaela; Langer, Erica; Hooten, Anthony J.; Roesler, Michelle; Hirsch, Betsy; Nguyen, Phuong L.; Cioc, Adina; Warlick, Erica; Ross, Julie A.

    2016-01-01

    Polymorphisms in mitochondrial DNA (mtDNA) are used to group individuals into haplogroups reflecting human global migration and are associated with multiple diseases, including cancer. Here, we evaluate the association between mtDNA haplogroup and risk of myelodysplastic syndromes (MDS). Cases were identified by the Minnesota Cancer Surveillance System (MCSS). Controls were identified through the Minnesota State driver’s license/identification card list. Because haplogroup frequencies vary by race and ethnicity, we restricted analyses to non-Hispanic whites. We genotyped 15 mtSNPs that capture common European mitochondrial haplogroup variation. We used SAS v.9.3 (SAS Institute, Cary, NC) to calculate odds ratios (OR) and 95% confidence intervals (CI) overall and stratified by MDS subtype and IPSS-R risk category. We were able to classify 215 cases with confirmed MDS and 522 controls into one of the 11 common European haplogroups. Due to small sample sizes in some subgroups, we combined mt haplogroups into larger bins based on the haplogroup evolutionary tree, including HV (H+V), JT (J+T), IWX (I+W+X), UK (U+K), and Z for comparisons of cases and controls. Using haplogroup HV as the reference group, we found a statistically significant association between haplogroup JT and MDS (OR=0.58, 95% CI 0.36, 0.92, P=0.02). No statistically significant heterogeneity was observed in subgroup analyses. In this population-based study of MDS, we observed an association between mtDNA haplogroup JT and risk of MDS. While previously published studies provide biological plausibility for the observed association, further studies of the relationship between mtDNA variation and MDS are warranted in larger sample sizes. PMID:27121678

  5. Association between mitochondrial DNA haplogroup and myelodysplastic syndromes.

    PubMed

    Poynter, Jenny N; Richardson, Michaela; Langer, Erica; Hooten, Anthony J; Roesler, Michelle; Hirsch, Betsy; Nguyen, Phuong L; Cioc, Adina; Warlick, Erica; Ross, Julie A

    2016-09-01

    Polymorphisms in mitochondrial DNA (mtDNA) are used to group individuals into haplogroups reflecting human global migration and are associated with multiple diseases, including cancer. Here, we evaluate the association between mtDNA haplogroup and risk of myelodysplastic syndromes (MDS). Cases were identified by the Minnesota Cancer Surveillance System. Controls were identified through the Minnesota State driver's license/identification card list. Because haplogroup frequencies vary by race and ethnicity, we restricted analyses to non-Hispanic whites. We genotyped 15 mtSNPs that capture common European mitochondrial haplogroup variation. We used SAS v.9.3 (SAS Institute, Cary, NC) to calculate odds ratios (OR) and 95% confidence intervals (CI) overall and stratified by MDS subtype and IPSS-R risk category. We were able to classify 215 cases with confirmed MDS and 522 controls into one of the 11 common European haplogroups. Due to small sample sizes in some subgroups, we combined mt haplogroups into larger bins based on the haplogroup evolutionary tree, including HV (H + V), JT (J + T), IWX (I + W + X), UK (U + K), and Z for comparisons of cases and controls. Using haplogroup HV as the reference group, we found a statistically significant association between haplogroup JT and MDS (OR = 0.58, 95% CI 0.36, 0.92, P = 0.02). No statistically significant heterogeneity was observed in subgroup analyses. In this population-based study of MDS, we observed an association between mtDNA haplogroup JT and risk of MDS. While previously published studies provide biological plausibility for the observed association, further studies of the relationship between mtDNA variation and MDS are warranted in larger sample sizes. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  6. Uncoupling of mitochondrial oxidative phosphorylation by DNA gyrase inhibitors

    SciTech Connect

    Gallagher, M.; Weinberg, R.; Simpson, M.V.

    1986-05-01

    Supercoiled mtDNA and the swivel requirement for its replication suggest the existence of a mtDNA gyrase. The authors published studies on isolated mitochondria showing that novobiocin, coumermycin, nalidixic acid, and oxolinic acid promote relaxed DNA formation at the expense of supercoiled DNA are in accord with this view. However, their inability to directly detect the enzyme led them to ask whether these drugs act elsewhere. Their results with isolated rat liver mitochondria show that novo, nal, but not oxo, stimulate O/sub 2/ uptake as much as does 2.4-dinitrophenol (DNP). This possible uncoupling effect was confirmed by a standard (/sup 32/P) assay showing the following inhibitions of ATP synthesis: 0.2 mM novo, 95% (0.4 mM, 100%) 0.4 mM nal, 37%; oxo to at least 1.9 mM, 0%; (0.5 mM 2,4-DNP, 100%). Thus, oxo remains a useful tool for intact mitochondrial studies. Because these three drugs, especially novo, are being used to study the role of DNA superhelicity on pro- and eucaryotic (and mitochondrial) gene expression, the authors studied their effect on oxidative phosphorylation in such cells. In these cases the drugs did not affect DNP-sensitive (/sup 14/C)glutamine transport into E. coli cells (an established measure of ATP level), nor, in an S. cerevisiae mutant permeable to novo, did novo affect the steady state ATP level. Studies on cultured mammalian cells are in progress.

  7. Mitochondrial DNA polymorphisms associated with longevity in the Turkish population.

    PubMed

    Guney, Ozgur; Ak, Handan; Atay, Sevcan; Ozkaya, Ali Burak; Aydin, Hikmet Hakan

    2014-07-01

    The accumulation of mutations in mitochondrial DNA is a widely recognized mechanism for aging and age related diseases. However, studies indicate that some mutations could be beneficial to longevity by slowing down the function of the electron transport chain, reducing free radical production. In this study, we re-sequenced the entire mitochondrial DNA from 50 individuals and examined aging-related variations in the Turkish population. We evaluated sequence data by comparing whole SNP frequencies, individual SNP frequencies, the effect of SNPs, SNP accumulation in certain mtDNA regions and haplotype profiles between elderly and control groups. The frequency of total mitochondrial SNPs was significantly higher in nonagenarians than controls (p=0.0094). Furthermore, non-coding, synonymous and tRNA mutations were more prevalent in the 90+ group compared to controls (p=0.0001, p<0.001, p=0.0096, respectively). A73G and C152T polymorphisms were significantly associated with longevity in the Turkish population (p=0.0086 and p=0.004, respectively). Additionally, C150T was specific to the 90+ group, but the difference failed to reach statistical significance (p=0.053). We also detected a novel transversion in the ATPase6 gene (C8899A) that was negatively associated with longevity (p=0.0016). Examining the distribution of SNPs among genes and functionally associated gene regions revealed a significant accumulation of mutations in the D-loop region and genes encoding Complex I subunits (ND1-6) (p<0.0001, p=0.0302, respectively). Moreover, there was an increase in the non-synonymous mutation frequency of Complex I genes in aged subjects (p<0.0001). Haplotype H was also significantly increased in the control group (p=0.0405). Overall, our findings support a role for mitochondrial genome variations and the functionality of oxidative phosphorylation in longevity. In this report, we sequenced the whole mtDNA of the Turkish population for the first time.

  8. Saami mitochondrial DNA reveals deep maternal lineage clusters.

    PubMed

    Delghandi, M; Utsi, E; Krauss, S

    1998-01-01

    The mitochondrial DNA of 62 Saami from the north of Norway was analyzed in the D loop hypervariable region I and II and sequences were compared to other gene pools. Two major (lineage 1 and 2) and two minor (lineage 3 and 4) maternal lineage clusters were found. Lineage 1 (56.9% of all hitherto analyzed Saami samples) contains a substantial number of branching haplotypes which are unknown in European gene pools. Lineage 2 (31.5%) and lineage 4 (3.6%) have few branching points and are present at a low rate throughout European gene pools. Lineage 3 (4.7%) has polymorphisms characteristic of circumpolar lineages.

  9. Accumulation of Mitochondrial DNA Mutations Disrupts Cardiac Progenitor Cell Function and Reduces Survival.

    PubMed

    Orogo, Amabel M; Gonzalez, Eileen R; Kubli, Dieter A; Baptista, Igor L; Ong, Sang-Bing; Prolla, Tomas A; Sussman, Mark A; Murphy, Anne N; Gustafsson, Åsa B

    2015-09-04

    Transfer of cardiac progenitor cells (CPCs) improves cardiac function in heart failure patients. However, CPC function is reduced with age, limiting their regenerative potential. Aging is associated with numerous changes in cells including accumulation of mitochondrial DNA (mtDNA) mutations, but it is unknown how this impacts CPC function. Here, we demonstrate that acquisition of mtDNA mutations disrupts mitochondrial function, enhances mitophagy, and reduces the replicative and regenerative capacities of the CPCs. We show that activation of differentiation in CPCs is associated with expansion of the mitochondrial network and increased mitochondrial oxidative phosphorylation. Interestingly, mutant CPCs are deficient in mitochondrial respiration and rely on glycolysis for energy. In response to differentiation, these cells fail to activate mitochondrial respiration. This inability to meet the increased energy demand leads to activation of cell death. These findings demonstrate the consequences of accumulating mtDNA mutations and the importance of mtDNA integrity in CPC homeostasis and regenerative potential.

  10. Survival and mitochondrial function in septic patients according to mitochondrial DNA haplogroup

    PubMed Central

    2012-01-01

    Introduction We recently found that platelet cytochrome c oxidase (COX) activities and quantities in 6-month-survival septic patients are significantly higher than those of patients who died before 6 months. Other studies suggested that the mitochondrial DNA (mtDNA) genotype could play a major role in sepsis survival. Given that COX catalytic subunits are encoded by mtDNA, the objective of the present study was to explore whether mtDNA population genetic variation could affect COX activity and quantity and favors sepsis survival. Methods A prospective, multicenter, observational study was carried out in six Spanish ICUs. We included 96 patients with severe sepsis. We determined the mtDNA haplogroup, the COX specific activity/citrate synthase specific activity (COXa/CSa) ratio and the COX quantity/citrate synthase specific activity (COXq/CSa) ratio in circulating platelets at the time of diagnosis, day 4 and day 8. We used survival at 1 and 6 months as endpoints. Results Patients with the JT mtDNA haplogroup (n = 15) showed higher COXq/CSa ratio at day 4 (P = 0.04) and day 8 (P = 0.02) than those with other haplogroups (n = 81). Logistic regression analysis showed that the JT mtDNA haplogroup (odds ratio = 0.18; 95% confidence interval = 0.04 to 0.94; P = 0.04) and COXq/CSa ratio (odds ratio = 0.53; 95% confidence interval = 0.30 to 0.93; P = 0.03) were associated with 1-month survival after controlling for age and lactic acid levels. Conclusions The novel findings of our study are that 1-month surviving septic patients showed higher COXq/CSa ratio than nonsurviving individuals, that patients from the JT mtDNA haplogroup showed a higher COXq/CSa ratio and that JT patients had a higher 1-month survival than patients from other mtDNA haplogroups. PMID:22251664

  11. Survival and mitochondrial function in septic patients according to mitochondrial DNA haplogroup.

    PubMed

    Lorente, Leonardo; Iceta, Ruth; Martín, María M; López-Gallardo, Esther; Solé-Violán, Jordi; Blanquer, José; Labarta, Lorenzo; Díaz, César; Jiménez, Alejandro; Montoya, Julio; Ruiz-Pesini, Eduardo

    2012-01-17

    We recently found that platelet cytochrome c oxidase (COX) activities and quantities in 6-month-survival septic patients are significantly higher than those of patients who died before 6 months. Other studies suggested that the mitochondrial DNA (mtDNA) genotype could play a major role in sepsis survival. Given that COX catalytic subunits are encoded by mtDNA, the objective of the present study was to explore whether mtDNA population genetic variation could affect COX activity and quantity and favors sepsis survival. A prospective, multicenter, observational study was carried out in six Spanish ICUs. We included 96 patients with severe sepsis. We determined the mtDNA haplogroup, the COX specific activity/citrate synthase specific activity (COXa/CSa) ratio and the COX quantity/citrate synthase specific activity (COXq/CSa) ratio in circulating platelets at the time of diagnosis, day 4 and day 8. We used survival at 1 and 6 months as endpoints. Patients with the JT mtDNA haplogroup (n=15) showed higher COXq/CSa ratio at day 4 (P=0.04) and day 8 (P=0.02) than those with other haplogroups (n=81). Logistic regression analysis showed that the JT mtDNA haplogroup (odds ratio=0.18; 95% confidence interval=0.04 to 0.94; P=0.04) and COXq/CSa ratio (odds ratio=0.53; 95% confidence interval=0.30 to 0.93; P=0.03) were associated with 1-month survival after controlling for age and lactic acid levels. The novel findings of our study are that 1-month surviving septic patients showed higher COXq/CSa ratio than nonsurviving individuals, that patients from the JT mtDNA haplogroup showed a higher COXq/CSa ratio and that JT patients had a higher 1-month survival than patients from other mtDNA haplogroups.

  12. The human mitochondrial single-stranded DNA-binding protein displays distinct kinetics and thermodynamics of DNA binding and exchange.

    PubMed

    Qian, Yufeng; Johnson, Kenneth A

    2017-08-04

    The human mitochondrial ssDNA-binding protein (mtSSB) is a homotetrameric protein, involved in mtDNA replication and maintenance. Although mtSSB is structurally similar to SSB from Escherichia coli (EcoSSB), it lacks the C-terminal disordered domain, and little is known about the biophysics of mtSSB-ssDNA interactions. Here, we characterized the kinetics and thermodynamics of mtSSB binding to ssDNA by equilibrium titrations and stopped-flow kinetic measurements. We show that the mtSSB tetramer can bind to ssDNA in two distinct binding modes: (SSB)30 and (SSB)60, defined by DNA binding site sizes of 30 and 60 nucleotides, respectively. We found that the binding mode is modulated by magnesium ion and NaCl concentration, but unlike EcoSSB, the mtSSB does not show negative intersubunit cooperativity. Global fitting of both the equilibrium and kinetic data afforded estimates for the rate and equilibrium constants governing the formation of (SSB)60 and (SSB)30 complexes and for the transitions between the two binding modes. We found that the mtSSB tetramer binds to ssDNA with a rate constant near the diffusion limit (2 × 10(9) m(-1) s(-1)) and that longer DNA (≥60 nucleotides) rapidly wraps around all four monomers, as revealed by FRET assays. We also show that the mtSSB tetramer can directly transfer from one ssDNA molecule to another via an intermediate with two DNA molecules bound to the mtSSB. In conclusion, our results indicate that human mtSSB shares many physicochemical properties with EcoSSB and that the differences may be explained by the lack of an acidic, disordered C-terminal tail in human mtSSB protein. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  13. Clonal expansion of early to mid-life mitochondrial DNA point mutations drives mitochondrial dysfunction during human ageing.

    PubMed

    Greaves, Laura C; Nooteboom, Marco; Elson, Joanna L; Tuppen, Helen A L; Taylor, Geoffrey A; Commane, Daniel M; Arasaradnam, Ramesh P; Khrapko, Konstantin; Taylor, Robert W; Kirkwood, Thomas B L; Mathers, John C; Turnbull, Douglass M

    2014-09-01

    Age-related decline in the integrity of mitochondria is an important contributor to the human ageing process. In a number of ageing stem cell populations, this decline in mitochondrial function is due to clonal expansion of individual mitochondrial DNA (mtDNA) point mutations within single cells. However the dynamics of this process and when these mtDNA mutations occur initially are poorly understood. Using human colorectal epithelium as an exemplar tissue with a well-defined stem cell population, we analysed samples from 207 healthy participants aged 17-78 years using a combination of techniques (Random Mutation Capture, Next Generation Sequencing and mitochondrial enzyme histochemistry), and show that: 1) non-pathogenic mtDNA mutations are present from early embryogenesis or may be transmitted through the germline, whereas pathogenic mtDNA mutations are detected in the somatic cells, providing evidence for purifying selection in humans, 2) pathogenic mtDNA mutations are present from early adulthood (<20 years of age), at both low levels and as clonal expansions, 3) low level mtDNA mutation frequency does not change significantly with age, suggesting that mtDNA mutation rate does not increase significantly with age, and 4) clonally expanded mtDNA mutations increase dramatically with age. These data confirm that clonal expansion of mtDNA mutations, some of which are generated very early in life, is the major driving force behind the mitochondrial dysfunction associated with ageing of the human colorectal epithelium.

  14. Sequence polymorphism in a novel noncoding region of Pacific oyster mitochondrial DNA.

    PubMed

    Aranishi, Futoshi; Okimoto, Takane

    2005-01-01

    Nucleotide sequence polymorphism in a 641-bp novel major noncoding region of mitochondrial DNA (mtDNA-NC) of the Pacific oyster Crassostrea gigas was analysed for 29 cultured individuals within the Goseong population. A total of 30 variable sites were detected, and the relative frequency of nucleotide alteration was determined to be 4.68. Alterations were mostly single nucleotide substitutions. Transition, transversion, both transition and transversion, and both transversion and nucleotide deletion were observed at 18, 9, 2 and 1 sites, respectively. Among 29 specimens, 22 haplotypes were identified, and pairwise genetic diversity of haplotypes was calculated to be 0.988 from multiple sequence substitutions using the two-parameter model. A phylogenetic tree, obtained for haplotypes by the neighbor-joining method, showed a single cluster of linkages. The cluster comprised 11 haplotypes associating with 14 specimens, while the other 11 haplotypes associating with 15 specimens were scattered. This mtDNA-NC presenting a high nucleotide sequence polymorphism is a potential mtDNA control region. It therefore can serve as a genetic marker for intraspecies phylogenetic analysis of the Pacific oyster and is more useful than the less polymorphic mtDNA coding genes.

  15. Interaction of mitochondrial potassium channels with the permeability transition pore.

    PubMed

    Cheng, Yu; Debska-Vielhaber, Grazyna; Siemen, Detlef

    2010-05-17

    Three types of potassium channels cooperate with the permeability transition pore (PTP) in the inner mitochondrial membranes of various tissues, mtK((ATP)), mtBK, and mtKv1.3. While the latter two share similarities with their plasma membrane counterparts, mtK((ATP)) exhibits considerable differences with the plasma membrane K((ATP))-channel. One important function seems to be suppression of release of proapototic substances from mitochondria through the PTP. Open potassium channels tend to keep the PTP closed thus acting as antiapoptotic. Nevertheless, in their mode of action there are considerable differences among them. This review introduces three K(+)-channels and the PTP, and discusses known facts about their interaction. Copyright 2009 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

  16. Structural heterogeneity of mitochondrial DNA molecules within the genus Drosophila.

    PubMed Central

    Fauron, C M; Wolstenholme, D R

    1976-01-01

    We have determined by electron microscopy the molecular weight of circular mitochondrial DNA (mtDNA) molecules from 39 species representing 13 groups of five subgenera of the genus Drosophila. mtDNA molecules of all species examined, other than members of the melanogaster group, had, with one exception, molecular weights in the rather narrow range 9.90 X 10(6). The one exception was D. robusta, which had a molecular weight of 10.61 X 10(6). In contrast, mtDNA molecules from species within the melanogaster group had molecular weights covering the considerably greater range 9.92 X 10(6) to 12.35 X 10(6). Applying the electron microscope denaturation mapping technique of Inman to mtDNA molecules of eight species of the melanogaster group, we found each of them to contain a region [presumably rich in adenine and thymine (A+T)] which denatured at a specific temperature (40 degrees) at which most of the remainder of the molecule remained undenatured. The size of the A+T-rich region was constant for mtDNA molecules of a species, but varied from 0.62 X 10(6) to 3.41 X 10(6) for mtDNA molecules of different species. It was demonstrated that the differences in molecular weights of the A+T-rich regions can almost completely account for the differences in total molecular weights of the mtDNA molecules from species of the melanogaster group. Images PMID:1068475

  17. Differentiation of mitochondrial DNA and Y chromosomes in Russian populations.

    PubMed

    Malyarchuk, Boris; Derenko, Miroslava; Grzybowski, Tomasz; Lunkina, Arina; Czarny, Jakub; Rychkov, Serge; Morozova, Irina; Denisova, Galina; Miścicka-Sliwka, Danuta

    2004-12-01

    The genetic composition of the Russian population was investigated by analyzing both mitochondrial DNA (mtDNA) and Y-chromosome loci polymorphisms that allow for the different components of a population gene pool to be studied, depending on the mode of DNA marker inheritance. mtDNA sequence variation was examined by using hypervariable segment I (HVSI) sequencing and restriction analysis of the haplogroup-specific sites in 325 individuals representing 5 Russian populations from the European part of Russia. The Y-chromosome variation was investigated in 338 individuals from 8 Russian populations (including 5 populations analyzed for mtDNA variation) using 12 binary markers. For both uniparental systems most of the observed haplogroups fell into major West Eurasian haplogroups (97.9% and 99.7% for mtDNA and Y-chromosome haplogroups, respectively). Multidimensional scaling analysis based on pairwise F(ST) values between mtDNA HVSI sequences in Russians compared to other European populations revealed a considerable heterogeneity of Russian populations; populations from the southern and western parts of Russia are separated from eastern and northern populations. Meanwhile, the multidimensional scaling analysis based on Y-chromosome haplogroup F(ST) values demonstrates that the Russian gene pool is close to central-eastern European populations, with a much higher similarity to the Baltic and Finno-Ugric male pools from northern European Russia. This discrepancy in the depth of penetration of mtDNA and Y-chromosome lineages characteristic for the most southwestern Russian populations into the east and north of eastern Europe appears to indicate that Russian colonization of the northeastern territories might have been accomplished mainly by males rather than by females.

  18. Phenotypic effects of cattle mitochondrial DNA in American bison.

    PubMed

    Derr, James N; Hedrick, Philip W; Halbert, Natalie D; Plough, Louis; Dobson, Lauren K; King, Julie; Duncan, Calvin; Hunter, David L; Cohen, Noah D; Hedgecock, Dennis

    2012-12-01

    Hybridization between endangered species and more common species is a significant problem in conservation biology because it may result in extinction or loss of adaptation. The historical reduction in abundance and geographic distribution of the American plains bison (Bison bison bison) and their recovery over the last 125 years is well documented. However, introgression from domestic cattle (Bos taurus) into the few remaining bison populations that existed in the late 1800s has now been identified in many modern bison herds. We examined the phenotypic effect of this ancestry by comparing weight and height of bison with cattle or bison mitochondrial DNA (mtDNA) from Santa Catalina Island, California (U.S.A.), a nutritionally stressful environment for bison, and of a group of age-matched feedlot bison males in Montana, a nutritionally rich environment. The environmental and nutritional differences between these 2 bison populations were very different and demonstrated the phenotypic effect of domestic cattle mtDNA in bison over a broad range of conditions. For example, the average weight of feedlot males that were 2 years of age was 2.54 times greater than that of males from Santa Catalina Island. In both environments, bison with cattle mtDNA had lower weight compared with bison with bison mtDNA, and on Santa Catalina Island, the height of bison with cattle mtDNA was lower than the height of bison with bison mtDNA. These data support the hypothesis that body size is smaller and height is lower in bison with domestic cattle mtDNA and that genomic integrity is important for the conservation of the American plains bison.

  19. Mitochondrial DNA variant interactions modify breast cancer risk.

    PubMed

    Covarrubias, Daniel; Bai, Ren-Kui; Wong, Lee-Jun C; Leal, Suzanne M

    2008-01-01

    Interactions between mitochondrial deoxyribonucleic acid (mtDNA) variants and the risk of developing breast cancer were investigated using DNA samples collected from non-Jewish European American breast cancer patients and ethnically age-matched female controls. Logistic regression was used to evaluate two-way interactions between 17 mtDNA variants. To control for multiple testing, empirical P values were calculated using permutation. Odds ratios (ORs) and corresponding 95% confidence intervals (CIs) were calculated to measure the contribution of variants in modifying the risk of developing breast cancer. A highly significant interaction was identified between variants 12308G and 10398G (empirical P value = 0.0028), with results suggesting these variants increase the risk of a woman developing breast cancer (OR = 3.03; 95% CI 1.53-6.11). Nominal significant P values were also observed for interactions between mtDNA variants 709A and 16189C; 4216C and 10398G; 4216C and 16189C; 10398G and 16159C; 13368A and 16189C; and 14766T and 16519C. However, after adjusting for multiple testing, the P values did not remain significant. Although it is important to elucidate the main effect of mtDNA variants on the risk of developing breast cancer, understanding gene x gene interactions will give a greater knowledge of disease etiology and aid in interpreting a woman's risk of developing breast cancer.

  20. Translesion Synthesis Past Acrolein-derived DNA Adducts by Human Mitochondrial DNA Polymerase γ*

    PubMed Central

    Kasiviswanathan, Rajesh; Minko, Irina G.; Lloyd, R. Stephen; Copeland, William C.

    2013-01-01

    Acrolein, a mutagenic aldehyde, is produced endogenously by lipid peroxidation and exogenously by combustion of organic materials, including tobacco products. Acrolein reacts with DNA bases forming exocyclic DNA adducts, such as γ-hydroxy-1,N2-propano-2′-deoxyguanosine (γ-HOPdG) and γ-hydroxy-1,N6-propano-2′-deoxyadenosine (γ-HOPdA). The bulky γ-HOPdG adduct blocks DNA synthesis by replicative polymerases but can be bypassed by translesion synthesis polymerases in the nucleus. Although acrolein-induced adducts are likely to be formed and persist in mitochondrial DNA, animal cell mitochondria lack specialized translesion DNA synthesis polymerases to tolerate these lesions. Thus, it is important to understand how pol γ, the sole mitochondrial DNA polymerase in human cells, acts on acrolein-adducted DNA. To address this question, we investigated the ability of pol γ to bypass the minor groove γ-HOPdG and major groove γ-HOPdA adducts using single nucleotide incorporation and primer extension analyses. The efficiency of pol γ-catalyzed bypass of γ-HOPdG was low, and surprisingly, pol γ preferred to incorporate purine nucleotides opposite the adduct. Pol γ also exhibited ∼2-fold lower rates of excision of the misincorporated purine nucleotides opposite γ-HOPdG compared with the corresponding nucleotides opposite dG. Extension of primers from the termini opposite γ-HOPdG was accomplished only following error-prone purine nucleotide incorporation. However, pol γ preferentially incorporated dT opposite the γ-HOPdA adduct and efficiently extended primers from the correctly paired terminus, indicating that γ-HOPdA is probably nonmutagenic. In summary, our data suggest that acrolein-induced exocyclic DNA lesions can be bypassed by mitochondrial DNA polymerase but, in the case of the minor groove γ-HOPdG adduct, at the cost of unprecedented high mutation rates. PMID:23543747

  1. Application of mitochondrial DNA polymorphism to meloidogyne molecular population biology.

    PubMed

    Hyman, B C; Whipple, L E

    1996-09-01

    Recent advances in molecular biology have enabled the genotyping of individual nematodes, facilitating the analysis of genetic variability within and among plant-pathogenic nematode isolates. This review first describes representative examples of how RFLP, RAPD, AFLP, and DNA sequence analysis have been employed to describe populations of several phytonematodes, including the pinewood, burrowing, root-knot, and cyst nematodes. The second portion of this paper evaluates the utility of a size-variable mitochondrial DNA locus to examine the genetic structure of Meloidogyne isolates using two alternate methodologies, variable number tandem repeat (VNTR) and repeat associated poiymorphism (RAP) analysis. VNTR analysis has revealed genetic variation among individual nematodes, whereas RAP may provide useful markers for species and population differentiation.

  2. Cardiac involvement in mitochondrial DNA disease: clinical spectrum, diagnosis, and management.

    PubMed

    Bates, Matthew G D; Bourke, John P; Giordano, Carla; d'Amati, Giulia; Turnbull, Douglass M; Taylor, Robert W

    2012-12-01

    Mitochondrial disease refers to a heterogenous group of genetic disorders that result from dysfunction of the final common pathway of energy metabolism. Mitochondrial DNA mutations affect key components of the respiratory chain and account for the majority of mitochondrial disease in adults. Owing to critical dependence of the heart on oxidative metabolism, cardiac involvement in mitochondrial disease is common and may occur as the principal clinical manifestation or part of multisystem disease. Recent advances in our understanding of the clinical spectrum and genetic aetiology of cardiac involvement in mitochondrial DNA disease have important implications for cardiologists in terms of the investigation and multi-disciplinary management of patients.

  3. Effect of mitochondrial apoptotic activation through the mitochondrial membrane permeability transition pore on yak meat tenderness during postmortem aging.

    PubMed

    Wang, Lin-Lin; Han, Ling; Ma, Xiu-Li; Yu, Qun-Li; Zhao, Suo-Nan

    2017-11-01

    The effect of membrane permeability transition pore dependent mitochondrial apoptotic activation on yak meat tenderness was investigated. Results indicate that MPTP opening increased significantly and the mitochondrial membrane potential decreased markedly in the early aging process (P<0.05). Cytochrome c was released from the mitochondria to the cytoplasm via the MPTP in the early period. Meanwhile, the activation of procaspase-9 occurred earlier than that of procaspase-3. Cyclosporin A suppressed the MPTP opening, depolarization of the mitochondrial membrane potential, activities of caspase-9 and caspase-3, apoptosis rate, myofibril fragmentation index, reactive oxygen species generation, and Ca(2+) levels. These results demonstrated that MPTP mediated the release of cytochrome c in the mitochondrial apoptotic pathway. Furthermore, yak meat tenderness was improved by mitochondrial apoptotic pathway during aging. MPTP opening may be influenced by the ROS generation and Ca(2+) overloading in yak meat during postmortem aging. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Replication stalling by catalytically impaired Twinkle induces mitochondrial DNA rearrangements in cultured cells.

    PubMed

    Pohjoismäki, Jaakko L O; Goffart, Steffi; Spelbrink, Johannes N

    2011-07-01

    Pathological mitochondrial DNA (mtDNA) rearrangements have been proposed to result from repair of double-strand breaks caused by blockage of mitochondrial DNA (mtDNA) replication. As mtDNA deletions are seen only in post-mitotic tissues, it has been suggested that they are selected out in actively dividing cells. By electron microscopy we observed rearranged mtDNA molecules in cultured human cells expressing a catalytically impaired helicase. As these molecules were undetectable by PCR, we propose that deleted mtDNA molecules in cultured cells are fragile and sensitive to heating. Further consequences of mtDNA replication stalling are discussed.

  5. Mitochondrial DNA haplogroup H structure in North Africa.

    PubMed

    Ennafaa, Hajer; Cabrera, Vicente M; Abu-Amero, Khaled K; González, Ana M; Amor, Mohamed B; Bouhaha, Rym; Dzimiri, Nduna; Elgaaïed, Amel B; Larruga, José M

    2009-02-25

    The Strait of Gibraltar separating the Iberian Peninsula from North Africa is thought to be a stronger barrier to gene flow for male than for female lineages. However, the recent subdivision of the haplogroup H at mitochondrial DNA (mtDNA) level has revealed greater genetic differentiation among geographic regions than previously detected. The dissection of the mtDNA haplogroup H in North Africa, and its comparison with the Iberian Peninsula and Near-East profiles would help clarify the relative affinities among these regions. Like the Iberian Peninsula, the dominant mtDNA haplogroup H subgroups in North Africa are H1 (42%) and H3 (13%). The similarity between these regions is stronger in the North-West edge affecting mainly Moroccan Arabs, West Saharans and Mauritanians, and decreases eastwards probably due to gene flow from Near East as attested for the higher frequencies of H4, H5, H7, H8 and H11 subgroups. Moroccan Berbers show stronger affinities with Tunisian and Tunisian Berbers than with Moroccan Arabs. Coalescence ages for H1 (11 +/- 2 ky) and H3 (11 +/- 4 ky) in North Africa point to the possibility of a late Palaeolithic settlement for these lineages similar to those found for other mtDNA haplogroups. Total and partial mtDNA genomic sequencing unveiled stronger mtDNA differentiation among regions than previously found using HVSI mtDNA based analysis. The subdivision of the mtDNA haplogroup H in North Africa has confirmed that the genetic differentiation found among Western and Eastern populations is mainly due to geographical rather than cultural barriers. It also shows that the historical Arabian role on the region had more a cultural than a demic effect. Whole mtDNA sequencing of identical H haplotypes based on HVSI and RFLP information has unveiled additional mtDNA differences between North African and Iberian Peninsula lineages, pointing to an older mtDNA genetic flow between regions than previously thought. Based on this new information, it seems

  6. Mitochondrial DNA haplogroup H structure in North Africa

    PubMed Central

    Ennafaa, Hajer; Cabrera, Vicente M; Abu-Amero, Khaled K; González, Ana M; Amor, Mohamed B; Bouhaha, Rym; Dzimiri, Nduna; Elgaaïed, Amel B; Larruga, José M

    2009-01-01

    Background The Strait of Gibraltar separating the Iberian Peninsula from North Africa is thought to be a stronger barrier to gene flow for male than for female lineages. However, the recent subdivision of the haplogroup H at mitochondrial DNA (mtDNA) level has revealed greater genetic differentiation among geographic regions than previously detected. The dissection of the mtDNA haplogroup H in North Africa, and its comparison with the Iberian Peninsula and Near-East profiles would help clarify the relative affinities among these regions. Results Like the Iberian Peninsula, the dominant mtDNA haplogroup H subgroups in North Africa are H1 (42%) and H3 (13%). The similarity between these regions is stronger in the North-West edge affecting mainly Moroccan Arabs, West Saharans and Mauritanians, and decreases eastwards probably due to gene flow from Near East as attested for the higher frequencies of H4, H5, H7, H8 and H11 subgroups. Moroccan Berbers show stronger affinities with Tunisian and Tunisian Berbers than with Moroccan Arabs. Coalescence ages for H1 (11 ± 2 ky) and H3 (11 ± 4 ky) in North Africa point to the possibility of a late Palaeolithic settlement for these lineages similar to those found for other mtDNA haplogroups. Total and partial mtDNA genomic sequencing unveiled stronger mtDNA differentiation among regions than previously found using HVSI mtDNA based analysis. Conclusion The subdivision of the mtDNA haplogroup H in North Africa has confirmed that the genetic differentiation found among Western and Eastern populations is mainly due to geographical rather than cultural barriers. It also shows that the historical Arabian role on the region had more a cultural than a demic effect. Whole mtDNA sequencing of identical H haplotypes based on HVSI and RFLP information has unveiled additional mtDNA differences between North African and Iberian Peninsula lineages, pointing to an older mtDNA genetic flow between regions than previously thought. Based on this

  7. Oxidants and not alkylating agents induce rapid mtDNA loss and mitochondrial dysfunction

    PubMed Central

    Furda, Amy M.; Marrangoni, Adele M.; Lokshin, Anna; Van Houten, Bennett

    2013-01-01

    Mitochondrial DNA (mtDNA) is essential for proper mitochondrial function and encodes 22 tRNAs, 2 rRNAs and 13 polypeptides that make up subunits of complex I, III, IV, in the electron transport chain and complex V, the ATP synthase. Although mitochondrial dysfunction has been implicated in processes such as premature aging, neurodegeneration, and cancer, it has not been shown whether persistent mtDNA damage causes a loss of oxidative phosphorylation. We addressed this question by treating mouse embryonic fibroblasts with either hydrogen peroxide (H2O2) or the alkylating agent methyl methanesulfonate (MMS) and measuring several endpoints, including mtDNA damage and repair rates using QPCR, levels of mitochondrial- and nuclear-encoded proteins using antibody analysis, and a pharmacologic profile of mitochondria using the Seahorse Extracellular Flux Analyzer. We show that a 60 min treatment with H2O2 causes persistent mtDNA lesions, mtDNA loss, decreased levels of a nuclear-encoded mitochondrial subunit, a loss of ATP-linked oxidative phosphorylation and a loss of total reserve capacity. Conversely, a 60 min treatment with 2 mM MMS causes persistent mtDNA lesions but no mtDNA loss, no decrease in levels of a nuclear-encoded mitochondrial subunit, and no mitochondrial dysfunction. These results suggest that persistent mtDNA damage is not sufficient to cause mitochondrial dysfunction. PMID:22766155

  8. 3-Nitropropionic acid induces autophagy by forming mitochondrial permeability transition pores rather than activatiing the mitochondrial fission pathway

    PubMed Central

    Solesio, Maria E; Saez-Atienzar, Sara; Jordan, Joaquin; Galindo, Maria F

    2013-01-01

    BACKGROUND AND PURPOSE Huntington's disease is a neurodegenerative process associated with mitochondrial alterations. Inhibitors of the electron–transport channel complex II, such as 3-nitropropionic acid (3NP), are used to study the molecular and cellular pathways involved in this disease. We studied the effect of 3NP on mitochondrial morphology and its involvement in macrophagy. EXPERIMENTAL APPROACH Pharmacological and biochemical methods were used to characterize the effects of 3NP on autophagy and mitochondrial morphology. SH-SY5Y cells were transfected with GFP-LC3, GFP-Drp1 or GFP-Bax to ascertain their role and intracellular localization after 3NP treatment using confocal microscopy. KEY RESULTS Untreated SH-SY5Y cells presented a long, tubular and filamentous net of mitochondria. After 3NP (5 mM) treatment, mitochondria became shorter and rounder. 3NP induced formation of mitochondrial permeability transition pores, both in cell cultures and in isolated liver mitochondria, and this process was inhibited by cyclosporin A. Participation of the mitochondrial fission pathway was excluded because 3NP did not induce translocation of the dynamin-related protein 1 (Drp1) to the mitochondria. The Drp1 inhibitor Mdivi-1 did not affect the observed changes in mitochondrial morphology. Finally, scavengers of reactive oxygen species failed to prevent mitochondrial alterations, while cyclosporin A, but not Mdivi-1, prevented the generation of ROS. CONCLUSIONS AND IMPLICATIONS There was a direct correlation between formation of mitochondrial permeability transition pores and autophagy induced by 3NP treatment. Activation of autophagy preceded the apoptotic process and was mediated, at least partly, by formation of reactive oxygen species and mitochondrial permeability transition pores. LINKED ARTICLE This article is commented on by González-Polo et al., pp. 60–62 of this issue. To view this commentary visit http://dx.doi.org/10.1111/j.1476-5381.2012.02203.x PMID

  9. 3-Nitropropionic acid induces autophagy by forming mitochondrial permeability transition pores rather than activating the mitochondrial fission pathway.

    PubMed

    Solesio, Maria E; Saez-Atienzar, Sara; Jordan, Joaquin; Galindo, Maria F

    2013-01-01

    Huntington's disease is a neurodegenerative process associated with mitochondrial alterations. Inhibitors of the electron-transport channel complex II, such as 3-nitropropionic acid (3NP), are used to study the molecular and cellular pathways involved in this disease. We studied the effect of 3NP on mitochondrial morphology and its involvement in macrophagy. Pharmacological and biochemical methods were used to characterize the effects of 3NP on autophagy and mitochondrial morphology. SH-SY5Y cells were transfected with GFP-LC3, GFP-Drp1 or GFP-Bax to ascertain their role and intracellular localization after 3NP treatment using confocal microscopy. Untreated SH-SY5Y cells presented a long, tubular and filamentous net of mitochondria. After 3NP (5 mM) treatment, mitochondria became shorter and rounder. 3NP induced formation of mitochondrial permeability transition pores, both in cell cultures and in isolated liver mitochondria, and this process was inhibited by cyclosporin A. Participation of the mitochondrial fission pathway was excluded because 3NP did not induce translocation of the dynamin-related protein 1 (Drp1) to the mitochondria. The Drp1 inhibitor Mdivi-1 did not affect the observed changes in mitochondrial morphology. Finally, scavengers of reactive oxygen species failed to prevent mitochondrial alterations, while cyclosporin A, but not Mdivi-1, prevented the generation of ROS. There was a direct correlation between formation of mitochondrial permeability transition pores and autophagy induced by 3NP treatment. Activation of autophagy preceded the apoptotic process and was mediated, at least partly, by formation of reactive oxygen species and mitochondrial permeability transition pores. © 2012 The Authors. British Journal of Pharmacology © 2012 The British Pharmacological Society.

  10. DNA Overstretching Transition: Ionic Strength Effects

    PubMed Central

    Punkkinen, Olli; Hansen, Per Lyngs; Miao, Ling; Vattulainen, Ilpo

    2005-01-01

    As double-stranded DNA is stretched to its B-form contour length, models of polymer elasticity can describe the dramatic increase in measured force. When the molecule is stretched beyond the contour length, it further shows a highly cooperative overstretching transition. We have developed a theoretical description for this transition by coupling the two-state model and the elasticity theory proposed earlier by others. Furthermore, we have extended this model to account for monovalent salt effects on elastic moduli during the transition. We find that this theoretical description is in very good agreement with recent measurements for the salt dependence of the overstretching transition, allowing us to gain insight into the mechanisms that govern the transition. In double-stranded DNA, the effective length per unit charge varies with salt in agreement with the Manning and Poisson-Boltzmann models for thin polyelectrolyte rods, whereas the other model parameters describing structural features have barely any salt dependence. The results thus suggest that the electrostatic component of force-induced overstretching is mediated mesoscopically via elasticity. PMID:15923227

  11. Complete genome sequence of mitochondrial DNA (mtDNA) of Chlorella sorokiniana.

    PubMed

    Orsini, Massimiliano; Costelli, Cristina; Malavasi, Veronica; Cusano, Roberto; Concas, Alessandro; Angius, Andrea; Cao, Giacomo

    2016-01-01

    The complete sequence of mitochondrial genome of the Chlorella sorokiniana strain (SAG 111-8 k) is presented in this work. Within the Chlorella genus, it represents the second species with a complete sequenced and annotated mitochondrial genome (GenBank accession no. KM241869). The genome consists of circular chromosomes of 52,528 bp and encodes a total of 31 protein coding genes, 3 rRNAs and 26 tRNAs. The overall AT contents of the C. sorokiniana mtDNA is 70.89%, while the coding sequence is of 97.4%.

  12. Distribution Patterns of Postmortem Damage in Human Mitochondrial DNA

    PubMed Central

    Gilbert, M. Thomas P.; Willerslev, Eske; Hansen, Anders J.; Barnes, Ian; Rudbeck, Lars; Lynnerup, Niels; Cooper, Alan

    2003-01-01

    The distribution of postmortem damage in mitochondrial DNA retrieved from 37 ancient human DNA samples was analyzed by cloning and was compared with a selection of published animal data. A relative rate of damage (ρv) was calculated for nucleotide positions within the human hypervariable region 1 (HVR1) and cytochrome oxidase subunit III genes. A comparison of damaged sites within and between the regions reveals that damage hotspots exist and that, in the HVR1, these correlate with sites known to have high in vivo mutation rates. Conversely, HVR1 subregions with known structural function, such as MT5, have lower in vivo mutation rates and lower postmortem-damage rates. The postmortem data also identify a possible functional subregion of the HVR1, termed “low-diversity 1,” through the lack of sequence damage. The amount of postmortem damage observed in mitochondrial coding regions was significantly lower than in the HVR1, and, although hotspots were noted, these did not correlate with codon position. Finally, a simple method for the identification of incorrect archaeological haplogroup designations is introduced, on the basis of the observed spectrum of postmortem damage. PMID:12489041

  13. Mitochondrial DNA variation of domestic sheep (Ovis aries) in Kenya.

    PubMed

    Resende, Adriana; Gonçalves, Joana; Muigai, Anne W T; Pereira, Filipe

    2016-06-01

    The history of domestic sheep (Ovis aries) in Africa remains largely unknown. After being first introduced from the Near East, sheep gradually spread through the African continent with pastoral societies. The eastern part of Africa was important either for the first diffusion of sheep southward or for putative secondary introductions from the Arabian Peninsula or southern Asia. We analysed mitochondrial DNA control region sequences of 91 domestic sheep from Kenya and found a high diversity of matrilines from the widespread haplogroup B, whereas only a single individual from haplogroup A was detected. Our phylogeography analyses of more than 500 available mitochondrial DNA sequences also identified ancestral haplotypes that were probably first introduced in Africa and are now widely distributed. Moreover, we found no evidence of an admixture between East and West African sheep. The presence of shared haplotypes in eastern and ancient southern African sheep suggests the possible southward movement of sheep along the eastern part of Africa. Finally, we found no evidence of an extensive introduction of sheep from southern Asia into Africa via the Indian Ocean trade. The overall findings on the phylogeography of East African domestic sheep set the grounds for understanding the origin and subsequent movements of sheep in Africa. The richness of maternal lineages in Kenyan breeds is of prime importance for future conservation and breeding programmes. © 2016 Stichting International Foundation for Animal Genetics.

  14. ER-mitochondria contacts couple mtDNA synthesis with mitochondrial division in human cells.

    PubMed

    Lewis, Samantha C; Uchiyama, Lauren F; Nunnari, Jodi

    2016-07-15

    Mitochondrial DNA (mtDNA) encodes RNAs and proteins critical for cell function. In human cells, hundreds to thousands of mtDNA copies are replicated asynchronously, packaged into protein-DNA nucleoids, and distributed within a dynamic mitochondrial network. The mechanisms that govern how nucleoids are chosen for replication and distribution are not understood. Mitochondrial distribution depends on division, which occurs at endoplasmic reticulum (ER)-mitochondria contact sites. These sites were spatially linked to a subset of nucleoids selectively marked by mtDNA polymerase and engaged in mtDNA synthesis--events that occurred upstream of mitochondrial constriction and division machine assembly. Our data suggest that ER tubules proximal to nucleoids are necessary but not sufficient for mtDNA synthesis. Thus, ER-mitochondria contacts coordinate licensing of mtDNA synthesis with division to distribute newly replicated nucleoids to daughter mitochondria.

  15. Genetics Home Reference: FBXL4-related encephalomyopathic mitochondrial DNA depletion syndrome

    MedlinePlus

    ... protein that is found within cell structures called mitochondria . Mitochondria are involved in a wide variety of cellular ... growth and division (proliferation) and cell death (apoptosis). Mitochondria contain their own DNA, known as mitochondrial DNA ( ...

  16. ER-mitochondria contacts couple mtDNA synthesis with mitochondrial division in human cells

    PubMed Central

    Lewis, Samantha C.; Uchiyama, Lauren F.; Nunnari, Jodi

    2017-01-01

    Mitochondrial DNA (mtDNA) encodes RNAs and proteins critical for cell function. In human cells, 100–1000s mtDNA copies are replicated asynchronously, packaged into protein-DNA nucleoids, and distributed within a dynamic mitochondrial network. The mechanisms that govern how nucleoids are chosen for replication and distribution are not understood. Mitochondrial distribution depends on division, which occurs at endoplasmic reticulum (ER)-mitochondria contact sites. These sites were spatially linked to a subset of nucleoids selectively marked by mtDNA polymerase and engaged in mtDNA synthesis, events that occurred upstream of mitochondrial constriction and division machine assembly. Our data suggest that ER tubules proximal to nucleoids were necessary but not sufficient for mtDNA synthesis. Thus, ER-mitochondria contacts coordinate licensing of mtDNA synthesis with division to distribute newly replicated nucleoids to daughter mitochondria. PMID:27418514

  17. Imeglimin prevents human endothelial cell death by inhibiting mitochondrial permeability transition without inhibiting mitochondrial respiration

    PubMed Central

    Detaille, D; Vial, G; Borel, A-L; Cottet-Rouselle, C; Hallakou-Bozec, S; Bolze, S; Fouqueray, P; Fontaine, E

    2016-01-01

    Imeglimin is the first in a new class of oral glucose-lowering agents, having recently completed its phase 2b trial. As Imeglimin did show a full prevention of β-cell apoptosis, and since angiopathy represents a major complication of diabetes, we studied Imeglimin protective effects on hyperglycemia-induced death of human endothelial cells (HMEC-1). These cells were incubated in several oxidative stress environments (exposure to high glucose and oxidizing agent tert-butylhydroperoxide) which led to mitochondrial permeability transition pore (PTP) opening, cytochrome c release and cell death. These events were fully prevented by Imeglimin treatment. This protective effect on cell death occurred without any effect on oxygen consumption rate, on lactate production and on cytosolic redox or phosphate potentials. Imeglimin also dramatically decreased reactive oxygen species production, inhibiting specifically reverse electron transfer through complex I. We conclude that Imeglimin prevents hyperglycemia-induced cell death in HMEC-1 through inhibition of PTP opening without inhibiting mitochondrial respiration nor affecting cellular energy status. Considering the high prevalence of macrovascular and microvascular complications in type 2 diabetic subjects, these results together suggest a potential benefit of Imeglimin in diabetic angiopathy. PMID:27551496

  18. Mitochondrial DNA Damage in Iron Overload*S⃞

    PubMed Central

    Gao, Xueshan; Campian, Jian Li; Qian, Mingwei; Sun, Xiao-Feng; Eaton, John W.

    2009-01-01

    Chronic iron overload has slow and insidious effects on heart, liver, and other organs. Because iron-driven oxidation of most biologic materials (such as lipids and proteins) is readily repaired, this slow progression of organ damage implies some kind of biological “memory.” We hypothesized that cumulative iron-catalyzed oxidant damage to mtDNA might occur in iron overload, perhaps explaining the often lethal cardiac dysfunction. Real time PCR was used to examine the “intactness” of mttDNA in cultured H9c2 rat cardiac myocytes. After 3–5 days exposure to high iron, these cells exhibited damage to mtDNA reflected by diminished amounts of near full-length 15.9-kb PCR product with no change in the amounts of a 16.1-kb product from a nuclear gene. With the loss of intact mtDNA, cellular respiration declined and mRNAs for three electron transport chain subunits and 16 S rRNA encoded by mtDNA decreased, whereas no decrements were found in four subunits encoded by nuclear DNA. To examine the importance of the interactions of iron with metabolically generated reactive oxygen species, we compared the toxic effects of iron in wild-type and rhoo cells. In wild-type cells, elevated iron caused increased production of reactive oxygen species, cytostasis, and cell death, whereas the rhoo cells were unaffected. We conclude that long-term damage to cells and organs in iron-overload disorders involves interactions between iron and mitochondrial reactive oxygen species resulting in cumulative damage to mtDNA, impaired synthesis of respiratory chain subunits, and respiratory dysfunction. PMID:19095657

  19. Mitochondrial DNA Haplogroups and Neurocognitive Impairment During HIV Infection

    PubMed Central

    Hulgan, Todd; Samuels, David C.; Bush, William; Ellis, Ronald J.; Letendre, Scott L.; Heaton, Robert K.; Franklin, Donald R.; Straub, Peter; Murdock, Deborah G.; Clifford, David B.; Collier, Ann C.; Gelman, Benjamin B.; Marra, Christina M.; McArthur, Justin C.; McCutchan, J. Allen; Morgello, Susan; Simpson, David M.; Grant, Igor; Kallianpur, Asha R.

    2015-01-01

    Background. Neurocognitive impairment (NCI) remains an important complication in persons infected with human immunodeficiency virus (HIV). Ancestry-related mitochondrial DNA (mtDNA) haplogroups have been associated with outcomes of HIV infection and combination antiretroviral therapy (CART), and with neurodegenerative diseases. We hypothesize that mtDNA haplogroups are associated with NCI in HIV-infected adults and performed a genetic association study in the CNS HIV Antiretroviral Therapy Effects Research (CHARTER) cohort. Methods. CHARTER is an observational study of ambulatory HIV-infected adults. Haplogroups were assigned using mtDNA sequence, and principal components were derived from ancestry-informative nuclear DNA variants. Outcomes were cross-sectional global deficit score (GDS) as a continuous measure, GDS impairment (GDS ≥ 0.50), and HIV-associated neurocognitive disorder (HAND) using international criteria. Multivariable models were adjusted for comorbidity status (incidental vs contributing), current CART, plasma HIV RNA, reading ability, and CD4 cell nadir. Results. Haplogroups were available from 1027 persons; median age 43 years, median CD4 nadir 178 cells/mm3, 72% on CART, and 46% with HAND. The 102 (9.9%) persons of genetically determined admixed Hispanic ancestry had more impairment by GDS or HAND than persons of European or African ancestry (P < .001 for all). In multivariate models including persons of admixed Hispanic ancestry, those with haplogroup B had lower GDS (β = −0.34; P = .008) and less GDS impairment (odds ratio = 0.16; 95% confidence interval, .04, .63; P = .009) than other haplogroups. There were no significant haplogroup associations among persons of European or African ancestry. Conclusions. In these mostly CART-treated persons, mtDNA haplogroup B was associated with less NCI among persons of genetically determined Hispanic ancestry. mtDNA variation may represent an ancestry-specific factor influencing NCI in HIV

  20. Mitochondrial DNA nucleotide changes in primary congenital glaucoma patients.

    PubMed

    Kumar, Manoj; Tanwar, Mukesh; Faiq, Muneeb Ahmad; Pani, Jhumur; Shamsi, Monis Bilal; Dada, Tanuj; Dada, Rima

    2013-01-01

    Primary congenital glaucoma (PCG) is the second most common cause of blindness, accounting for 0.01%-0.04% of total blindness worldwide. Most congenital glaucoma cases are mapped to the GLC3A locus, and many aspects of PCG are still unknown. Recent studies have reported an increased frequency of mitochondrial DNA (mtDNA) sequence changes in primary open-angle glaucoma, primary angle-closure glaucoma, and pseudoexfoliation glaucoma compared to controls. Thus, this study was planned with the aim of detecting mitochondrial DNA variations in PCG cases. Twenty primary congenital glaucoma cases were selected from Dr. R. P. Centre for Ophthalmic Sciences of All India Institute of Medical Sciences (AIIMS), New Delhi, India. DNA was isolated from whole blood samples. The entire coding region of the mitochondrial genome was amplified by PCR in 20 patients and 20 controls. The full mtDNA genome was sequenced and analyzed against mitochondrial reference sequence NC_012920. MtDNA sequencing revealed a total of 195 nucleotide variations in PCG patients and 58 in controls. Of the 195 changes, 43 (22.05%) were nonsynonymous, 82 (42.05%) were synonymous, and 30 were in RNA genes. A total of 39/195 (20.00%) variations were observed in the D-loop (hypervariable region), 19/195 (9.74%) in different ribosomal RNA (rRNAs), 11/195 (5.64%) in transfer RNA (tRNAs), 66/195 (33.84%) in complex I, 17/195 (8.71%) in complex III, 27/195 (13.84%) in complex IV, and 15/195 (7.69%) in complex V. Of 58 variations in the controls, 14 were nonsynonymous changes. The Sorting Intolerant from Tolerant and Polymorphism Phenotyping analyses of all nonsynonymous changes from patients revealed two pathogenic changes in NADH-ubiquinone oxidoreductase chain 2 (ND2) and cytochrome oxidase subunit III (COXIII) subunits. In one of the patients, the insertion of cytosine introduced a frame shift change (p.Ile104AsnfsX26) in the cytochrome b (CYB) subunit of the electron transport chain. In another patient, a

  1. The interplay between inflammation, oxidative stress, DNA damage, DNA repair and mitochondrial dysfunction in depression.

    PubMed

    Czarny, Piotr; Wigner, Paulina; Galecki, Piotr; Sliwinski, Tomasz

    2017-06-29

    A growing body of evidence suggests that inflammation, mitochondrial dysfunction and oxidant-antioxidant imbalance may play a significant role in the development and progression of depression. Elevated levels of reactive oxygen and nitrogen species - a result of oxidant-antioxidant imbalance - may lead to increased damage of biomolecules, including DNA. This was confirmed in depressed patients in a research study conducted by our team and other scientists. 8-oxoguanine - a marker of oxidative DNA damage - was found in the patients' lymphocytes, urine and serum. These results were confirmed using a comet assay on lymphocytes. Furthermore, it was shown that the patients' cells repaired peroxide-induced DNA damage less efficiently than controls' cells and that some single nucleotide polymorphisms (SNP) of the genes involved in oxidative DNA damage repair may modulate the risk of depression. Lastly, less efficient DNA damage repair observed in the patients can be, at least partly, attributed to the presence of specific SNP variants, as it was revealed through a genotype-phenotype analysis. In conclusion, the available literature shows that both oxidative stress and less efficient DNA damage repair may lead to increased DNA damage in depressed patients. A similar mechanism may result in mitochondrial dysfunction, which is observed in depression. Copyright © 2017 Elsevier Inc. All rights reserved.

  2. Wnt Signaling Prevents the Aβ Oligomer-Induced Mitochondrial Permeability Transition Pore Opening Preserving Mitochondrial Structure in Hippocampal Neurons

    PubMed Central

    Arrázola, Macarena S.; Ramos-Fernández, Eva; Cisternas, Pedro; Ordenes, Daniela; Inestrosa, Nibaldo C.

    2017-01-01

    Alzheimer’s disease (AD) is a neurodegenerative disorder mainly known for synaptic impairment and neuronal cell loss, affecting memory processes. Beside these damages, mitochondria have been implicated in the pathogenesis of AD through the induction of the mitochondrial permeability transition pore (mPTP). The mPTP is a non-selective pore that is formed under apoptotic conditions, disturbing mitochondrial structure and thus, neuronal viability. In AD, Aβ oligomers (Aβos) favor the opening of the pore, activating mitochondria-dependent neuronal cell death cascades. The Wnt signaling activated through the ligand Wnt3a has been described as a neuroprotective signaling pathway against amyloid-β (Aβ) peptide toxicity in AD. However, the mechanisms by which Wnt signaling prevents Aβos-induced neuronal cell death are unclear. We proposed here to study whether Wnt signaling protects neurons earlier than the late damages in the progression of the disease, through the preservation of the mitochondrial structure by the mPTP inhibition. To study specific events related to mitochondrial permeabilization we performed live-cell imaging from primary rat hippocampal neurons, and electron microscopy to analyze the mitochondrial morphology and structure. We report here that Wnt3a prevents an Aβos-induced cascade of mitochondrial events that leads to neuronal cell death. This cascade involves (a) mPTP opening, (b) mitochondrial swelling, (c) mitochondrial membrane potential loss and (d) cytochrome c release, thus leading to neuronal cell death. Furthermore, our results suggest that the activation of the Wnt signaling prevents mPTP opening by two possible mechanisms, which involve the inhibition of mitochondrial GSK-3β and/or the modulation of mitochondrial hexokinase II levels and activity. This study suggests a possible new approach for the treatment of AD from a mitochondrial perspective, and will also open new lines of study in the field of Wnt signaling in neuroprotection

  3. Wnt Signaling Prevents the Aβ Oligomer-Induced Mitochondrial Permeability Transition Pore Opening Preserving Mitochondrial Structure in Hippocampal Neurons.

    PubMed

    Arrázola, Macarena S; Ramos-Fernández, Eva; Cisternas, Pedro; Ordenes, Daniela; Inestrosa, Nibaldo C

    2017-01-01

    Alzheimer's disease (AD) is a neurodegenerative disorder mainly known for synaptic impairment and neuronal cell loss, affecting memory processes. Beside these damages, mitochondria have been implicated in the pathogenesis of AD through the induction of the mitochondrial permeability transition pore (mPTP). The mPTP is a non-selective pore that is formed under apoptotic conditions, disturbing mitochondrial structure and thus, neuronal viability. In AD, Aβ oligomers (Aβos) favor the opening of the pore, activating mitochondria-dependent neuronal cell death cascades. The Wnt signaling activated through the ligand Wnt3a has been described as a neuroprotective signaling pathway against amyloid-β (Aβ) peptide toxicity in AD. However, the mechanisms by which Wnt signaling prevents Aβos-induced neuronal cell death are unclear. We proposed here to study whether Wnt signaling protects neurons earlier than the late damages in the progression of the disease, through the preservation of the mitochondrial structure by the mPTP inhibition. To study specific events related to mitochondrial permeabilization we performed live-cell imaging from primary rat hippocampal neurons, and electron microscopy to analyze the mitochondrial morphology and structure. We report here that Wnt3a prevents an Aβos-induced cascade of mitochondrial events that leads to neuronal cell death. This cascade involves (a) mPTP opening, (b) mitochondrial swelling, (c) mitochondrial membrane potential loss and (d) cytochrome c release, thus leading to neuronal cell death. Furthermore, our results suggest that the activation of the Wnt signaling prevents mPTP opening by two possible mechanisms, which involve the inhibition of mitochondrial GSK-3β and/or the modulation of mitochondrial hexokinase II levels and activity. This study suggests a possible new approach for the treatment of AD from a mitochondrial perspective, and will also open new lines of study in the field of Wnt signaling in neuroprotection.

  4. Analysis of mitochondrial DNA polymorphisms in Guangdong Han Chinese.

    PubMed

    Chen, Feng; Wang, Sha-Yan; Zhang, Ruan-Zhang; Hu, Yu-Hua; Gao, Guo-Feng; Liu, Yan-Hui; Kong, Qing-Peng

    2008-03-01

    Previous investigations on Chinese mitochondrial DNA (mtDNA) variation revealed that the matrilineal gene pool of southern Han Chinese is rather complex, with much higher genetic diversity and more basal/ancient lineages than the northern Hans. The extreme case is Guangdong Han populations, among which pronounced (matrilineal) differentiation has been observed, indicative of complex demography of the region. To get more insights into the maternal makeup of southern Han Chinese, mtDNA variation of a total of 106 individuals sampled from Dongguan, Guangdong Province, China, was analyzed in this study. With the aid of the information from control-region hypervariable segments I and II (HVS-I and -II) as well as some necessary coding-region segments, the phylogenetic status of all mtDNAs under examination were determined according to the reconstructed East Asian mtDNA tree. In this way, the mtDNAs have been classified into various haplogroups or sub-haplogroups. The southern-prevalent haplogroups, such as R9 (20.8%), B (17.9%), M7b (14.2%), show relatively high distribution frequencies in Dongguan Hans; whereas the frequencies of Northern-prevalent haplogroups (with the exception of D) are quite low: C (1.9%), G2 (1.9%) and Z (1.9%), indicating the southern-origin of Dongguan Hans.

  5. RNA mapping on Drosophila mitochondrial DNA: precursors and template strands.

    PubMed Central

    Berthier, F; Renaud, M; Alziari, S; Durand, R

    1986-01-01

    Drosophila melanogaster mitochondrial DNA (mtDNA) is closely related to the mammalian and amphibian mtDNA except for gene organization. In Drosophila, genes are distributed in clusters alternatively coded on each strand. Besides the eleven major foreseeable transcripts previously described (MERTEN and PARDUE, 1981, J. Mol. Biol., 153, 1-21), we have characterized two poly A+ transcripts, one major and one minor which could correspond respectively to the ND3 and ND6 reading frames, and 27 poly A+ minor transcripts (0.2 to greater than 3.2 kb) which are distributed along the mtDNA except in the rRNAs, ND 1 and A+ T rich regions. The mapping and length of 25 of these transcripts strongly suggest a precursor role. They would be processed at the level of tRNA or tRNA-like sequences. Most of them are transcribed from the template strand of each gene cluster and their distribution is in agreement with the hypothesis of several transcription origins and terminations located near the extremities of each gene cluster. Quantitatively our results show a large variation in each presumptive mature transcript compared to the other, even in a given gene cluster, suggesting a specific degradation of some of the mature transcripts. Images PMID:3086843

  6. Mitochondrial DNA Variation in Southeastern Pre-Columbian Canids.

    PubMed

    Brzeski, Kristin E; DeBiasse, Melissa B; Rabon, David R; Chamberlain, Michael J; Taylor, Sabrina S

    2016-05-01

    The taxonomic status of the red wolf (Canis rufus) is heavily debated, but could be clarified by examining historic specimens from the southeastern United States. We analyzed mitochondrial DNA (mtDNA) from 3 ancient (350-1900 year olds) putative wolf samples excavated from middens and sinkholes within the historic red wolf range. We detected 3 unique mtDNA haplotypes, which grouped with the coyote mtDNA clade, suggesting that the canids inhabiting southeastern North America prior to human colonization from Europe were either coyotes, which would vastly expand historic coyote distributions, an ancient coyote-wolf hybrid, or a North American evolved red wolf lineage related to coyotes. Should the red wolf prove to be a distinct species, our results support the idea of either an ancient hybrid origin for red wolves or a shared common ancestor between coyotes and red wolves. © The American Genetic Association. 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  7. Mitochondrial DNA damage induces apoptosis in senescent cells

    PubMed Central

    Laberge, R-M; Adler, D; DeMaria, M; Mechtouf, N; Teachenor, R; Cardin, G B; Desprez, P-Y; Campisi, J; Rodier, F

    2013-01-01

    Senescence is a cellular response to damage and stress. The senescence response prevents cancer by suppressing the proliferation of cells with a compromised genome and contributes to optimal wound healing in normal tissues. Persistent senescent cells are also thought to drive aging and age-associated pathologies through their secretion of inflammatory factors that modify the tissue microenvironment and alter the function of nearby normal or transformed cells. Understanding how senescent cells alter the microenvironment would be aided by the ability to induce or eliminate senescent cells at will in vivo. Here, we combine the use of the synthetic nucleoside analog ganciclovir (GCV) with herpes simplex virus thymidine kinase (HSVtk) activity to create or eliminate senescent human cells. We show that low concentrations of GCV induce senescence through the accumulation of nuclear DNA damage while higher concentrations of GCV, similar to those used in vivo, kill non-dividing senescent cells via mitochondrial DNA (mtDNA) damage and caspase-dependent apoptosis. Using this system, we effectively eliminated xenografted normal human senescent fibroblasts or induced senescence in human breast cancer cells in vivo. Thus, cellular senescence and mtDNA damage are outcomes of synthetic nucleoside analog treatment, indicating that the GCV–HSVtk combination can be used effectively to promote the targeted formation or eradication of senescent cells. PMID:23868060

  8. Mitochondrial DNA damage induces apoptosis in senescent cells.

    PubMed

    Laberge, R-M; Adler, D; DeMaria, M; Mechtouf, N; Teachenor, R; Cardin, G B; Desprez, P-Y; Campisi, J; Rodier, F

    2013-07-18

    Senescence is a cellular response to damage and stress. The senescence response prevents cancer by suppressing the proliferation of cells with a compromised genome and contributes to optimal wound healing in normal tissues. Persistent senescent cells are also thought to drive aging and age-associated pathologies through their secretion of inflammatory factors that modify the tissue microenvironment and alter the function of nearby normal or transformed cells. Understanding how senescent cells alter the microenvironment would be aided by the ability to induce or eliminate senescent cells at will in vivo. Here, we combine the use of the synthetic nucleoside analog ganciclovir (GCV) with herpes simplex virus thymidine kinase (HSVtk) activity to create or eliminate senescent human cells. We show that low concentrations of GCV induce senescence through the accumulation of nuclear DNA damage while higher concentrations of GCV, similar to those used in vivo, kill non-dividing senescent cells via mitochondrial DNA (mtDNA) damage and caspase-dependent apoptosis. Using this system, we effectively eliminated xenografted normal human senescent fibroblasts or induced senescence in human breast cancer cells in vivo. Thus, cellular senescence and mtDNA damage are outcomes of synthetic nucleoside analog treatment, indicating that the GCV-HSVtk combination can be used effectively to promote the targeted formation or eradication of senescent cells.

  9. Revealing latitudinal patterns of mitochondrial DNA diversity in Chileans.

    PubMed

    Gómez-Carballa, Alberto; Moreno, Fabián; Álvarez-Iglesias, Vanesa; Martinón-Torres, Federico; García-Magariños, Manuel; Pantoja-Astudillo, Jaime A; Aguirre-Morales, Eugenia; Bustos, Patricio; Salas, Antonio

    2016-01-01

    The territory of Chile is particularly long and narrow, which combined with its mountainous terrain, makes it a unique scenario for human genetic studies. We obtained 995 control region mitochondrial DNA (mtDNA) sequences from Chileans representing populations living at different latitudes of the country from the North to the southernmost region. The majority of the mtDNA profiles are of Native American origin (∼88%). The remaining haplotypes are mostly of recent European origin (∼11%), and only a minor proportion is of recent African ancestry (∼1%). While these proportions are relatively uniform across the country, more structured patterns of diversity emerge when examining the variation from a phylogeographic perspective. For instance, haplogroup A2 reaches ∼9% in the North, and its frequency decreases gradually to ∼1% in the southernmost populations, while the frequency of haplogroup D (sub-haplogroups D1 and D4) follows the opposite pattern: 36% in the southernmost region, gradually decreasing to 21% in the North. Furthermore, there are remarkable signatures of founder effects in specific sub-clades of Native American (e.g. haplogroups D1j and D4p) and European (e.g. haplogroups T2b3 and K1a4a1a+195) ancestry. We conclude that the magnitude of the latitudinal differences observed in the patterns of mtDNA variation might be relevant in forensic casework.

  10. Amplification of Mitochondrial DNA for detection of Plasmodiumvivax in Balochistan.

    PubMed

    Shahwani, Muhammad Naeem; Nisar, Samia; Aleem, Abdul; Panezai, Marina; Afridi, Sarwat; Malik, Shaukat Iqbal

    2017-05-01

    To access a new step using PCR to amplify the targeted mtDNA sequence for detecting specifically Plasmodium vivax and its co-infections, false positive and false negative results with Plasmodium falciparum. In this study we have standardized a new technical approach in which the target mitochondrial DNA sequence (mtDNA) was amplified by using a PCR technique as a tool to detect Plasmodium spp. Species specific primers were designed to hybridize with cytochrome c oxidase gene of P. vivax (cox I) and P. falciparum (cox III). Two hundred blood samples were collected on the basis of clinical symptoms which were initially examined through microscopic analysis after preparing Giemsa stained thick and thin blood smears. Afterwards genomic DNA was extracted from all samples and was then subjected to PCR amplification by using species specific primers and amplified segments were sequenced for confirmation of results. One-hundred and thirty-two blood samples were detected as positive for malaria by PCR, out of which 64 were found to be positive by PCR and 53 by both microscopy and PCR for P.vivax infection. Nine samples were found to be false negative, one P.vivax mono infection was declared as co infection by PCR and 3 samples identified as having P.falciparum gametes were confirmed as P.vivax by PCR amplification. Sensitivity and specificity were found to be 85% and 92% respectively. Results obtained through PCR method were comparatively better and reliable than microscopy.

  11. A restriction map of Xenopus laevis mitochondrial DNA.

    PubMed

    Cordonnier, A M; Vannier, P A; Brun, G M

    1982-08-01

    The mitochondrial DNA from Xenopus laevis is a 17.4 x 10(3)-base-pair circular DNA molecule. The mapping of this DNA, using 19 different restriction endonucleases is reported here. The sites are as follows: 1 for BamHI, PstI, SacI, SalI, BalI; 2 for BglII, SacII, EcoRI, ClaI, 3 for XhoI, 4 for AvaI, XbaI, PvuII, 5 for HindIII, 6 for HhaI, BclI, HpaI, 10 for AvaII and 11 for HincII. The same sites (except for one of the two ClaI sites) are observed in the molecule cloned in pBR322 DNA. The fragments corresponding to 62 cleavage sites have all been ordered and precisely located. They provide suitable conditions for further investigations connected with the study of replication and nucleotide sequence determination of this molecule.

  12. Mitochondrial DNA variation in the Viking age population of Norway.

    PubMed

    Krzewińska, Maja; Bjørnstad, Gro; Skoglund, Pontus; Olason, Pall Isolfur; Bill, Jan; Götherström, Anders; Hagelberg, Erika

    2015-01-19

    The medieval Norsemen or Vikings had an important biological and cultural impact on many parts of Europe through raids, colonization and trade, from about AD 793 to 1066. To help understand the genetic affinities of the ancient Norsemen, and their genetic contribution to the gene pool of other Europeans, we analysed DNA markers in Late Iron Age skeletal remains from Norway. DNA was extracted from 80 individuals, and mitochondrial DNA polymorphisms were detected by next-generation sequencing. The sequences of 45 ancient Norwegians were verified as genuine through the identification of damage patterns characteristic of ancient DNA. The ancient Norwegians were genetically similar to previously analysed ancient Icelanders, and to present-day Shetland and Orkney Islanders, Norwegians, Swedes, Scots, English, German and French. The Viking Age population had higher frequencies of K*, U*, V* and I* haplogroups than their modern counterparts, but a lower proportion of T* and H* haplogroups. Three individuals carried haplotypes that are rare in Norway today (U5b1b1, Hg A* and an uncommon variant of H*). Our combined analyses indicate that Norse women were important agents in the overseas expansion and settlement of the Vikings, and that women from the Orkneys and Western Isles contributed to the colonization of Iceland. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

  13. Mitochondrial DNA variation in the Viking age population of Norway

    PubMed Central

    Krzewińska, Maja; Bjørnstad, Gro; Skoglund, Pontus; Olason, Pall Isolfur; Bill, Jan; Götherström, Anders; Hagelberg, Erika

    2015-01-01

    The medieval Norsemen or Vikings had an important biological and cultural impact on many parts of Europe through raids, colonization and trade, from about AD 793 to 1066. To help understand the genetic affinities of the ancient Norsemen, and their genetic contribution to the gene pool of other Europeans, we analysed DNA markers in Late Iron Age skeletal remains from Norway. DNA was extracted from 80 individuals, and mitochondrial DNA polymorphisms were detected by next-generation sequencing. The sequences of 45 ancient Norwegians were verified as genuine through the identification of damage patterns characteristic of ancient DNA. The ancient Norwegians were genetically similar to previously analysed ancient Icelanders, and to present-day Shetland and Orkney Islanders, Norwegians, Swedes, Scots, English, German and French. The Viking Age population had higher frequencies of K*, U*, V* and I* haplogroups than their modern counterparts, but a lower proportion of T* and H* haplogroups. Three individuals carried haplotypes that are rare in Norway today (U5b1b1, Hg A* and an uncommon variant of H*). Our combined analyses indicate that Norse women were important agents in the overseas expansion and settlement of the Vikings, and that women from the Orkneys and Western Isles contributed to the colonization of Iceland. PMID:25487335

  14. Holes influence the mutation spectrum of human mitochondrial DNA

    NASA Astrophysics Data System (ADS)

    Villagran, Martha; Miller, John

    Mutations drive evolution and disease, showing highly non-random patterns of variant frequency vs. nucleotide position. We use computational DNA hole spectroscopy [M.Y. Suarez-Villagran & J.H. Miller, Sci. Rep. 5, 13571 (2015)] to reveal sites of enhanced hole probability in selected regions of human mitochondrial DNA. A hole is a mobile site of positive charge created when an electron is removed, for example by radiation or contact with a mutagenic agent. The hole spectra are quantum mechanically computed using a two-stranded tight binding model of DNA. We observe significant correlation between spectra of hole probabilities and of genetic variation frequencies from the MITOMAP database. These results suggest that hole-enhanced mutation mechanisms exert a substantial, perhaps dominant, influence on mutation patterns in DNA. One example is where a trapped hole induces a hydrogen bond shift, known as tautomerization, which then triggers a base-pair mismatch during replication. Our results deepen overall understanding of sequence specific mutation rates, encompassing both hotspots and cold spots, which drive molecular evolution.

  15. Mitochondrial DNA variation and language replacements in the Caucasus.

    PubMed

    Nasidze, I; Stoneking, M

    2001-06-07

    Sequences of the first hypervariable segment of the mitochondrial DNA (mtDNA) control region were obtained from 353 individuals representing nine groups and four major linguistic families (Indo-European, Altaic and North and South Caucasian) of the Caucasus region. The diversity within and between Caucasus populations exceeded the diversity within Europe, but was less than that in the Near East. Caucasus populations occupy an intermediate position between European and Near Eastern populations in tree and principal coordinate analyses, suggesting that they are either ancestral to European populations or derived via admixture from European and Near Eastern populations. The genetic relationships among Caucasus populations reflect geographical rather than linguistic relationships. In particular, the Indo-European-speaking Armenians and Altaic-speaking Azerbaijanians are most closely related to their nearest geographical neighbours in the Caucasus, not their linguistic neighbours (i.e. other Indo-European or Altaic populations). The mtDNA evidence thus suggests that the Armenian and Azerbaijanian languages represent instances of language replacement that had little impact on the mtDNA gene pool.

  16. Genetic Variation and Geographic Differentiation in Mitochondrial DNA of the Horseshoe Crab, LIMULUS POLYPHEMUS

    PubMed Central

    Saunders, Nancy C.; Kessler, Louis G.; Avise, John C.

    1986-01-01

    Restriction site variation in mitochondrial DNA (mtDNA) of the horseshoe crab (Limulus polyphemus) was surveyed in populations ranging from New Hampshire to the Gulf Coast of Florida. MtDNA clonal diversity was moderately high, particularly in southern samples, and a major genetic "break" (nucleotide sequence divergence approximately 2%) distinguished all sampled individuals which were north vs. south of a region in northeastern Florida. The area of genotypic divergence in Limulus corresponds to a long-recognized zoogeographic boundary between warm-temperate and tropical marine faunas, and it suggests that selection pressures and/or gene flow barriers associated with water mass differences may also influence the evolution of species widely distributed across such transition zones. On the other hand, a comparison of the mtDNA divergence patterns in Limulus with computer models involving stochastic lineage extinction in species with limited gene flow demonstrates that deterministic explanations need not necessarily be invoked to account for the observations. Experiments to distinguish stochastic from deterministic possibilities are suggested. Overall, the pattern and magnitude of mtDNA differentiation in horseshoe crabs is very similar to that typically reported for freshwater and terrestrial species assayed over a comparable geographic range. Results demonstrate for the first time that, geographically, at least some continuously distributed marine organisms can show considerable mtDNA genetic differentiation. PMID:17246319

  17. Primer effect in the detection of mitochondrial DNA point heteroplasmy by automated sequencing.

    PubMed

    Calatayud, Marta; Ramos, Amanda; Santos, Cristina; Aluja, Maria Pilar

    2013-06-01

    The correct detection of mitochondrial DNA (mtDNA) heteroplasmy by automated sequencing presents methodological constraints. The main goals of this study are to investigate the effect of sense and distance of primers in heteroplasmy detection and to test if there are differences in the accurate determination of heteroplasmy involving transitions or transversions. A gradient of the heteroplasmy levels was generated for mtDNA positions 9477 (transition G/A) and 15,452 (transversion C/A). Amplification and subsequent sequencing with forward and reverse primers, situated at 550 and 150 bp from the heteroplasmic positions, were performed. Our data provide evidence that there is a significant difference between the use of forward and reverse primers. The forward primer is the primer that seems to give a better approximation to the real proportion of the variants. No significant differences were found concerning the distance at which the sequencing primers were placed neither between the analysis of transitions and transversions. The data collected in this study are a starting point that allows to glimpse the importance of the sequencing primers in the accurate detection of point heteroplasmy, providing additional insight into the overall automated sequencing strategy.

  18. The levels of male gametic mitochondrial DNA are highly regulated in angiosperms with regard to mitochondrial inheritance.

    PubMed

    Wang, Dan-Yang; Zhang, Quan; Liu, Yang; Lin, Zhi-Fu; Zhang, Shao-Xiang; Sun, Meng-Xiang; Sodmergen

    2010-07-01

    The mechanisms that regulate mitochondrial inheritance are not yet clear, even though it is 100 years since the first description of non-Mendelian genetics. Here, we quantified the copy numbers of mitochondrial DNA (mtDNA) in the gametic cells of angiosperm species. We demonstrate that each egg cell from Arabidopsis thaliana, Antirrhinum majus, and Nicotiana tabacum possesses 59.0, 42.7, and 73.0 copies of mtDNA on average, respectively. These values are equivalent to those in Arabidopsis mesophyll cells, at 61.7 copies per cell. On the other hand, sperm or generative cells from Arabidopsis, A. majus, and N. tabacum possess minor amounts of mtDNA, at 0.083, 0.47, and 1 copy on average, respectively. We further reveal a 50-fold degradation of mtDNA during pollen development in A. majus. In contrast, markedly high levels of mtDNA are found in the male gametic cells of Cucumis melo and Pelargonium zonale (1296.3 and 256.7 copies, respectively). Our results provide direct evidence for mitochondrial genomic insufficiency in the eggs and somatic cells and indicate that a male gamete of an angiosperm may possess mtDNA at concentrations as high as 21-fold (C. melo) or as low as 0.1% (Arabidopsis) of the levels in somatic cells. These observations reveal the existence of a strong regulatory system for the male gametic mtDNA levels in angiosperms with regard to mitochondrial inheritance.

  19. The Levels of Male Gametic Mitochondrial DNA Are Highly Regulated in Angiosperms with Regard to Mitochondrial Inheritance[W

    PubMed Central

    Wang, Dan-Yang; Zhang, Quan; Liu, Yang; Lin, Zhi-Fu; Zhang, Shao-Xiang; Sun, Meng-Xiang; Sodmergen

    2010-01-01

    The mechanisms that regulate mitochondrial inheritance are not yet clear, even though it is 100 years since the first description of non-Mendelian genetics. Here, we quantified the copy numbers of mitochondrial DNA (mtDNA) in the gametic cells of angiosperm species. We demonstrate that each egg cell from Arabidopsis thaliana, Antirrhinum majus, and Nicotiana tabacum possesses 59.0, 42.7, and 73.0 copies of mtDNA on average, respectively. These values are equivalent to those in Arabidopsis mesophyll cells, at 61.7 copies per cell. On the other hand, sperm or generative cells from Arabidopsis, A. majus, and N. tabacum possess minor amounts of mtDNA, at 0.083, 0.47, and 1 copy on average, respectively. We further reveal a 50-fold degradation of mtDNA during pollen development in A. majus. In contrast, markedly high levels of mtDNA are found in the male gametic cells of Cucumis melo and Pelargonium zonale (1296.3 and 256.7 copies, respectively). Our results provide direct evidence for mitochondrial genomic insufficiency in the eggs and somatic cells and indicate that a male gamete of an angiosperm may possess mtDNA at concentrations as high as 21-fold (C. melo) or as low as 0.1% (Arabidopsis) of the levels in somatic cells. These observations reveal the existence of a strong regulatory system for the male gametic mtDNA levels in angiosperms with regard to mitochondrial inheritance. PMID:20605854

  20. Segregation of naturally occurring mitochondrial DNA variants in a mini-pig model

    USDA-ARS?s Scientific Manuscript database

    Within cells and tissues, the maternally inherited mitochondrial genome (mtDNA) is present in multimeric form and can harbour naturally occurring variants. Whilst high variant load can cause mitochondrial disease, naturally occurring mtDNA variants likely persist at low levels across generations of ...

  1. Restriction site heteroplasmy in the mitochondrial DNA of the marine fish Sciaenops ocellatus (L.).

    PubMed

    Gold, J R; Richardson, L R

    1990-01-01

    Restriction site heteroplasmy involving the enzymes NcoI and XbaI was detected in the mitochondrial DNAs of two individuals of the marine fish Sciaenops ocellatus. This represents only the sixth documented example of mitochondrial DNA restriction site heteroplasmy in animals. Two heteroplasmic individuals were found in a survey of nearly 750 individuals, suggesting that in most studies the incidence of mitochondrial DNA site heteroplasmy may be too low to be routinely detected.

  2. Next-generation sequencing reveals DGUOK mutations in adult patients with mitochondrial DNA multiple deletions

    PubMed Central

    Garone, Caterina; Bordoni, Andreina; Gutierrez Rios, Purificacion; Calvo, Sarah E.; Ripolone, Michela; Ranieri, Michela; Rizzuti, Mafalda; Villa, Luisa; Magri, Francesca; Corti, Stefania; Bresolin, Nereo; Mootha, Vamsi K.; Moggio, Maurizio; DiMauro, Salvatore; Comi, Giacomo P.; Sciacco, Monica

    2012-01-01

    The molecular diagnosis of mitochondrial disorders still remains elusive in a large proportion of patients, but advances in next generation sequencing are significantly improving our chances to detect mutations even in sporadic patients. Syndromes associated with mitochondrial DNA multiple deletions are caused by different molecular defects resulting in a wide spectrum of predominantly adult-onset clinical presentations, ranging from progressive external ophthalmoplegia to multi-systemic disorders of variable severity. The mutations underlying these conditions remain undisclosed in half of the affected subjects. We applied next-generation sequencing of known mitochondrial targets (MitoExome) to probands presenting with adult-onset mitochondrial myopathy and harbouring mitochondrial DNA multiple deletions in skeletal muscle. We identified autosomal recessive mutations in the DGUOK gene (encoding mitochondrial deoxyguanosine kinase), which has previously been associated with an infantile hepatocerebral form of mitochondrial DNA depletion. Mutations in DGUOK occurred in five independent subjects, representing 5.6% of our cohort of patients with mitochondrial DNA multiple deletions, and impaired both muscle DGUOK activity and protein stability. Clinical presentations were variable, including mitochondrial myopathy with or without progressive external ophthalmoplegia, recurrent rhabdomyolysis in a young female who had received a liver transplant at 9 months of age and adult-onset lower motor neuron syndrome with mild cognitive impairment. These findings reinforce the concept that mutations in genes involved in deoxyribonucleotide metabolism can cause diverse clinical phenotypes and suggest that DGUOK should be screened in patients harbouring mitochondrial DNA deletions in skeletal muscle. PMID:23043144

  3. Presequence-Independent Mitochondrial Import of DNA Ligase Facilitates Establishment of Cell Lines with Reduced mtDNA Copy Number

    PubMed Central

    Spadafora, Domenico; Kozhukhar, Natalia; Alexeyev, Mikhail F.

    2016-01-01

    Due to the essential role played by mitochondrial DNA (mtDNA) in cellular physiology and bioenergetics, methods for establishing cell lines with altered mtDNA content are of considerable interest. Here, we report evidence for the existence in mammalian cells of a novel, low- efficiency, presequence-independent pathway for mitochondrial protein import, which facilitates mitochondrial uptake of such proteins as Chlorella virus ligase (ChVlig) and Escherichia coli LigA. Mouse cells engineered to depend on this pathway for mitochondrial import of the LigA protein for mtDNA maintenance had severely (up to >90%) reduced mtDNA content. These observations were used to establish a method for the generation of mouse cell lines with reduced mtDNA copy number by, first, transducing them with a retrovirus encoding LigA, and then inactivating in these transductants endogenous Lig3 with CRISPR-Cas9. Interestingly, mtDNA depletion to an average level of one copy per cell proceeds faster in cells engineered to maintain mtDNA at low copy number. This makes a low-mtDNA copy number phenotype resulting from dependence on mitochondrial import of DNA ligase through presequence-independent pathway potentially useful for rapidly shifting mtDNA heteroplasmy through partial mtDNA depletion. PMID:27031233

  4. Presequence-Independent Mitochondrial Import of DNA Ligase Facilitates Establishment of Cell Lines with Reduced mtDNA Copy Number.

    PubMed

    Spadafora, Domenico; Kozhukhar, Natalia; Alexeyev, Mikhail F

    2016-01-01

    Due to the essential role played by mitochondrial DNA (mtDNA) in cellular physiology and bioenergetics, methods for establishing cell lines with altered mtDNA content are of considerable interest. Here, we report evidence for the existence in mammalian cells of a novel, low- efficiency, presequence-independent pathway for mitochondrial protein import, which facilitates mitochondrial uptake of such proteins as Chlorella virus ligase (ChVlig) and Escherichia coli LigA. Mouse cells engineered to depend on this pathway for mitochondrial import of the LigA protein for mtDNA maintenance had severely (up to >90%) reduced mtDNA content. These observations were used to establish a method for the generation of mouse cell lines with reduced mtDNA copy number by, first, transducing them with a retrovirus encoding LigA, and then inactivating in these transductants endogenous Lig3 with CRISPR-Cas9. Interestingly, mtDNA depletion to an average level of one copy per cell proceeds faster in cells engineered to maintain mtDNA at low copy number. This makes a low-mtDNA copy number phenotype resulting from dependence on mitochondrial import of DNA ligase through presequence-independent pathway potentially useful for rapidly shifting mtDNA heteroplasmy through partial mtDNA depletion.

  5. Proliferation of mitochondria in chronically stimulated rabbit skeletal muscle--transcription of mitochondrial genes and copy number of mitochondrial DNA.

    PubMed

    Schultz, J; Wiesner, R J

    2000-12-01

    Mitochondrial proliferation was studied in chronically stimulated rabbit skeletal muscle over a period of 50 days. After this time, subunits of COX had increased about fourfold. Corresponding mRNAs, encoded on mitochondrial DNA as well as on nuclear genes, were unchanged when related to total tissue RNA, however, they were elevated two- to fivefold when the massive increase of ribosomes per unit mass of muscle was taken into account. The same was true for the mRNA encoding mitochondrial transcription factor A. Surprisingly, tissue levels of mtTFA protein were reduced about twofold, together with mitochondrial DNA. In conclusion, mitochondria are able to maintain high rates of mitochondrial transcription even in the presence of reduced mtTFA protein and mtDNA levels. Therefore, stimulated mtTFA gene expression accompanies stimulated mitochondrial transcription, as in other models, but it is not sufficient for an increase of mtDNA copy number and other, yet unknown, factors have to be postulated.

  6. DNA nanotechnology. Programming colloidal phase transitions with DNA strand displacement.

    PubMed

    Rogers, W Benjamin; Manoharan, Vinothan N

    2015-02-06

    DNA-grafted nanoparticles have been called "programmable atom-equivalents": Like atoms, they form three-dimensional crystals, but unlike atoms, the particles themselves carry information (the sequences of the grafted strands) that can be used to "program" the equilibrium crystal structures. We show that the programmability of these colloids can be generalized to the full temperature-dependent phase diagram, not just the crystal structures themselves. We add information to the buffer in the form of soluble DNA strands designed to compete with the grafted strands through strand displacement. Using only two displacement reactions, we program phase behavior not found in atomic systems or other DNA-grafted colloids, including arbitrarily wide gas-solid coexistence, reentrant melting, and even reversible transitions between distinct crystal phases. Copyright © 2015, American Association for the Advancement of Science.

  7. An Overview of Ten Italian Horse Breeds through Mitochondrial DNA.

    PubMed

    Cardinali, Irene; Lancioni, Hovirag; Giontella, Andrea; Capodiferro, Marco Rosario; Capomaccio, Stefano; Buttazzoni, Luca; Biggio, Giovanni Paolo; Cherchi, Raffaele; Albertini, Emidio; Olivieri, Anna; Cappelli, Katia; Achilli, Alessandro; Silvestrelli, Maurizio

    2016-01-01

    The climatic and cultural diversity of the Italian Peninsula triggered, over time, the development of a great variety of horse breeds, whose origin and history are still unclear. To clarify this issue, analyses on phenotypic traits and genealogical data were recently coupled with molecular screening. To provide a comprehensive overview of the horse genetic variability in Italy, we produced and phylogenetically analyzed 407 mitochondrial DNA (mtDNA) control-region sequences from ten of the most important Italian riding horse and pony breeds: Bardigiano, Esperia, Giara, Lipizzan, Maremmano, Monterufolino, Murgese, Sarcidano, Sardinian Anglo-Arab, and Tolfetano. A collection of 36 Arabian horses was also evaluated to assess the genetic consequences of their common use for the improvement of some local breeds. In Italian horses, all previously described domestic mtDNA haplogroups were detected as well as a high haplotype diversity. These findings indicate that the ancestral local mares harbored an extensive genetic diversity. Moreover, the limited haplotype sharing (11%) with the Arabian horse reveals that its impact on the autochthonous mitochondrial gene pools during the final establishment of pure breeds was marginal, if any. The only significant signs of genetic structure and differentiation were detected in the geographically most isolated contexts (i.e. Monterufolino and Sardinian breeds). Such a geographic effect was also confirmed in a wider breed setting, where the Italian pool stands in an intermediate position together with most of the other Mediterranean stocks. However, some notable exceptions and peculiar genetic proximities lend genetic support to historical theories about the origin of specific Italian breeds.

  8. Cancer-associated isocitrate dehydrogenase mutations induce mitochondrial DNA instability.

    PubMed

    Kingsbury, Joanne M; Shamaprasad, Nachiketha; Billmyre, R Blake; Heitman, Joseph; Cardenas, Maria E

    2016-08-15

    A major advance in understanding the progression and prognostic outcome of certain cancers, such as low-grade gliomas, acute myeloid leukaemia, and chondrosarcomas, has been the identification of early-occurring mutations in the NADP(+)-dependent isocitrate dehydrogenase genes IDH1 and IDH2 These mutations result in the production of the onco-metabolite D-2-hydroxyglutarate (2HG), thought to contribute to disease progression. To better understand the mechanisms of 2HG pathophysiology, we introduced the analogous glioma-associated mutations into the NADP(+ )isocitrate dehydrogenase genes (IDP1, IDP2, IDP3) in Saccharomyces cerevisiae Intriguingly, expression of the mitochondrial IDP1(R148H) mutant allele results in high levels of 2HG production as well as extensive mtDNA loss and respiration defects. We find no evidence for a reactive oxygen-mediated mechanism mediating this mtDNA loss. Instead, we show that 2HG production perturbs the iron sensing mechanisms as indicated by upregulation of the Aft1-controlled iron regulon and a concomitant increase in iron levels. Accordingly, iron chelation, or overexpression of a truncated AFT1 allele that dampens transcription of the iron regulon, suppresses the loss of respirative capacity. Additional suppressing factors include overexpression of the mitochondrial aldehyde dehydrogenase gene ALD5 or disruption of the retrograde response transcription factor RTG1 Furthermore, elevated α-ketoglutarate levels also suppress 2HG-mediated respiration loss; consistent with a mechanism by which 2HG contributes to mtDNA loss by acting as a toxic α-ketoglutarate analog. Our findings provide insight into the mechanisms that may contribute to 2HG oncogenicity in glioma and acute myeloid leukaemia progression, with the promise for innovative diagnostic and prognostic strategies and novel therapeutic modalities.

  9. Cancer-associated isocitrate dehydrogenase mutations induce mitochondrial DNA instability

    PubMed Central

    Kingsbury, Joanne M.; Shamaprasad, Nachiketha; Billmyre, R. Blake; Heitman, Joseph; Cardenas, Maria E.

    2016-01-01

    A major advance in understanding the progression and prognostic outcome of certain cancers, such as low-grade gliomas, acute myeloid leukaemia, and chondrosarcomas, has been the identification of early-occurring mutations in the NADP+-dependent isocitrate dehydrogenase genes IDH1 and IDH2. These mutations result in the production of the onco-metabolite D-2-hydroxyglutarate (2HG), thought to contribute to disease progression. To better understand the mechanisms of 2HG pathophysiology, we introduced the analogous glioma-associated mutations into the NADP+ isocitrate dehydrogenase genes (IDP1, IDP2, IDP3) in Saccharomyces cerevisiae. Intriguingly, expression of the mitochondrial IDP1R148H mutant allele results in high levels of 2HG production as well as extensive mtDNA loss and respiration defects. We find no evidence for a reactive oxygen-mediated mechanism mediating this mtDNA loss. Instead, we show that 2HG production perturbs the iron sensing mechanisms as indicated by upregulation of the Aft1-controlled iron regulon and a concomitant increase in iron levels. Accordingly, iron chelation, or overexpression of a truncated AFT1 allele that dampens transcription of the iron regulon, suppresses the loss of respirative capacity. Additional suppressing factors include overexpression of the mitochondrial aldehyde dehydrogenase gene ALD5 or disruption of the retrograde response transcription factor RTG1. Furthermore, elevated α-ketoglutarate levels also suppress 2HG-mediated respiration loss; consistent with a mechanism by which 2HG contributes to mtDNA loss by acting as a toxic α-ketoglutarate analog. Our findings provide insight into the mechanisms that may contribute to 2HG oncogenicity in glioma and acute myeloid leukaemia progression, with the promise for innovative diagnostic and prognostic strategies and novel therapeutic modalities. PMID:27427385

  10. An Overview of Ten Italian Horse Breeds through Mitochondrial DNA

    PubMed Central

    Capodiferro, Marco Rosario; Capomaccio, Stefano; Buttazzoni, Luca; Biggio, Giovanni Paolo; Cherchi, Raffaele; Albertini, Emidio; Olivieri, Anna; Cappelli, Katia; Achilli, Alessandro; Silvestrelli, Maurizio

    2016-01-01

    Background The climatic and cultural diversity of the Italian Peninsula triggered, over time, the development of a great variety of horse breeds, whose origin and history are still unclear. To clarify this issue, analyses on phenotypic traits and genealogical data were recently coupled with molecular screening. Methodology To provide a comprehensive overview of the horse genetic variability in Italy, we produced and phylogenetically analyzed 407 mitochondrial DNA (mtDNA) control-region sequences from ten of the most important Italian riding horse and pony breeds: Bardigiano, Esperia, Giara, Lipizzan, Maremmano, Monterufolino, Murgese, Sarcidano, Sardinian Anglo-Arab, and Tolfetano. A collection of 36 Arabian horses was also evaluated to assess the genetic consequences of their common use for the improvement of some local breeds. Conclusions In Italian horses, all previously described domestic mtDNA haplogroups were detected as well as a high haplotype diversity. These findings indicate that the ancestral local mares harbored an extensive genetic diversity. Moreover, the limited haplotype sharing (11%) with the Arabian horse reveals that its impact on the autochthonous mitochondrial gene pools during the final establishment of pure breeds was marginal, if any. The only significant signs of genetic structure and differentiation were detected in the geographically most isolated contexts (i.e. Monterufolino and Sardinian breeds). Such a geographic effect was also confirmed in a wider breed setting, where the Italian pool stands in an intermediate position together with most of the other Mediterranean stocks. However, some notable exceptions and peculiar genetic proximities lend genetic support to historical theories about the origin of specific Italian breeds. PMID:27054850

  11. Extent of heterogeneity in mitochondrial DNA of European populations.

    PubMed

    Melton, T; Wilson, M; Batzer, M; Stoneking, M

    1997-05-01

    Variation in the mitochondrial DNA (mtDNA) control region as detected by sequence-specific oligonucleotide (SSO) probes is described for 595 individuals from six European or European-derived populations. Estimates of diversity for mtDNA types exceed 0.91 in all populations, while 50% of the 158 types which were observed occur only once. Of 68 shared types, most occur rarely (< 3% of the total population); only one type occurs at a frequency greater than 10%, and it is present at comparable frequencies in all six populations (18-29%). An analysis of molecular variance (AMOVA) incorporating genetic distances between types shows that 100% of the variation present in the total sample is attributable to within-population diversity, while there are essentially no between-population differences. Another AMOVA was performed for the first hypervariable region SSO sites only, which included this sample plus an additional 537 SSO types from mine more European populations that were inferred from published mtDNA control region sequence data. Similar results were obtained, with over 99% of the variation overall attributable to within-population differences, and less than 1% of the variation attributable to between-population differences. The Saami were the most different from other populations, which had been observed in an earlier study of nucleotide sequence data. Overall, there is no statistically significant heterogeneity for European populations (p > 0.001), and these groups are virtually indistinguishable with respect to mtDNA SSO types. These results demonstrate the utility of mtDNA typing for forensic investigations.

  12. Mitochondrial DNA (mtDNA) haplogroups in 1526 unrelated individuals from 11 Departments of Colombia.

    PubMed

    Yunis, Juan J; Yunis, Emilio J

    2013-09-01

    The frequencies of four mitochondrial Native American DNA haplogroups were determined in 1526 unrelated individuals from 11 Departments of Colombia and compared to the frequencies previously obtained for Amerindian and Afro-Colombian populations. Amerindian mtDNA haplogroups ranged from 74% to 97%. The lowest frequencies were found in Departments on the Caribbean coast and in the Pacific region, where the frequency of Afro-Colombians is higher, while the highest mtDNA Amerindian haplogroup frequencies were found in Departments that historically have a strong Amerindian heritage. Interestingly, all four mtDNA haplogroups were found in all Departments, in contrast to the complete absence of haplogroup D and high frequencies of haplogroup A in Amerindian populations in the Caribbean region of Colombia. Our results indicate that all four Native American mtDNA haplogroups were widely distributed in Colombia at the time of the Spanish conquest.

  13. Mitochondrial DNA (mtDNA) haplogroups in 1526 unrelated individuals from 11 Departments of Colombia

    PubMed Central

    Yunis, Juan J.; Yunis, Emilio J.

    2013-01-01

    The frequencies of four mitochondrial Native American DNA haplogroups were determined in 1526 unrelated individuals from 11 Departments of Colombia and compared to the frequencies previously obtained for Amerindian and Afro-Colombian populations. Amerindian mtDNA haplogroups ranged from 74% to 97%. The lowest frequencies were found in Departments on the Caribbean coast and in the Pacific region, where the frequency of Afro-Colombians is higher, while the highest mtDNA Amerindian haplogroup frequencies were found in Departments that historically have a strong Amerindian heritage. Interestingly, all four mtDNA haplogroups were found in all Departments, in contrast to the complete absence of haplogroup D and high frequencies of haplogroup A in Amerindian populations in the Caribbean region of Colombia. Our results indicate that all four Native American mtDNA haplogroups were widely distributed in Colombia at the time of the Spanish conquest. PMID:24130438

  14. DNA double-strand breaks activate ATM independent of mitochondrial dysfunction in A549 cells.

    PubMed

    Kalifa, Lidza; Gewandter, Jennifer S; Staversky, Rhonda J; Sia, Elaine A; Brookes, Paul S; O'Reilly, Michael A

    2014-10-01

    Excessive nuclear or mitochondrial DNA damage can lead to mitochondrial dysfunction, decreased energy production, and increased generation of reactive oxygen species (ROS). Although numerous cell signaling pathways are activated when cells are injured, the ataxia telangiectasia mutant (ATM) protein has emerged as a major regulator of the response to both mitochondrial dysfunction and nuclear DNA double-strand breaks (DSBs). Because mitochondrial dysfunction is often a response to excessive DNA damage, it has been difficult to determine whether nuclear and/or mitochondrial DNA DSBs activate ATM independent of mitochondrial dysfunction. In this study, mitochondrial and nuclear DNA DSBs were generated in the A549 human lung adenocarcinoma cell line by infecting with retroviruses expressing the restriction endonuclease PstI fused to a mitochondrial targeting sequence (MTS) or nuclear localization sequence (NLS) and a hemagglutinin antigen epitope tag (HA). Expression of MTS-PstI-HA or NLS-PstI-HA activated the DNA damage response defined by phosphorylation of ATM, the tumor suppressor protein p53 (TP53), KRAB-associated protein (KAP)-1, and structural maintenance of chromosomes (SMC)-1. Phosphorylated ATM and SMC1 were detected in nuclear fractions, whereas phosphorylated TP53 and KAP1 were detected in both mitochondrial and nuclear fractions. PstI also enhanced expression of the cyclin-dependent kinase inhibitor p21 and inhibited cell growth. This response to DNA damage occurred in the absence of detectable mitochondrial dysfunction and excess production of ROS. These findings reveal that DNA DSBs are sufficient to activate ATM independent of mitochondrial dysfunction and suggest that the activated form of ATM and some of its substrates are restricted to the nuclear compartment, regardless of the site of DNA damage. Copyright © 2014 Elsevier Inc. All rights reserved.

  15. Mic60/Mitofilin determines MICOS assembly essential for mitochondrial dynamics and mtDNA nucleoid organization

    PubMed Central

    Li, H; Ruan, Y; Zhang, K; Jian, F; Hu, C; Miao, L; Gong, L; Sun, L; Zhang, X; Chen, S; Chen, H; Liu, D; Song, Z

    2016-01-01

    The MICOS complex (mitochondrial contact site and cristae organizing system) is essential for mitochondrial inner membrane organization and mitochondrial membrane contacts, however, the molecular regulation of MICOS assembly and the physiological functions of MICOS in mammals remain obscure. Here, we report that Mic60/Mitofilin has a critical role in the MICOS assembly, which determines the mitochondrial morphology and mitochondrial DNA (mtDNA) organization. The downregulation of Mic60/Mitofilin or Mic19/CHCHD3 results in instability of other MICOS components, disassembly of MICOS complex and disorganized mitochondrial cristae. We show that there exists direct interaction between Mic60/Mitofilin and Mic19/CHCHD3, which is crucial for their stabilization in mammals. Importantly, we identified that the mitochondrial i-AAA protease Yme1L regulates Mic60/Mitofilin homeostasis. Impaired MICOS assembly causes the formation of 'giant mitochondria' because of dysregulated mitochondrial fusion and fission. Also, mtDNA nucleoids are disorganized and clustered in these giant mitochondria in which mtDNA transcription is attenuated because of remarkable downregulation of some key mtDNA nucleoid-associated proteins. Together, these findings demonstrate that Mic60/Mitofilin homeostasis regulated by Yme1L is central to the MICOS assembly, which is required for maintenance of mitochondrial morphology and organization of mtDNA nucleoids. PMID:26250910

  16. Impaired mitochondrial respiration and decreased fatigue resistance followed by severe muscle weakness in skeletal muscle of mitochondrial DNA mutator mice.

    PubMed

    Yamada, Takashi; Ivarsson, Niklas; Hernández, Andrés; Fahlström, Andreas; Cheng, Arthur J; Zhang, Shi-Jin; Bruton, Joseph D; Ulfhake, Brun; Westerblad, Håkan

    2012-12-01

    Mitochondrial dysfunction can drastically impair muscle function, with weakness and exercise intolerance as key symptoms. Here we examine the time course of development of muscle dysfunction in a mouse model of premature ageing induced by defective proofreading function of mitochondrial DNA (mtDNA) polymerase (mtDNA mutator mouse). Isolated fast-twitch muscles and single muscle fibres from young (3-5 months) and end-stage (11 months) mtDNA mutator mice were compared to age-matched control mice. Force and free myoplasmic [Ca(2+)] ([Ca(2+)](i)) were measured under resting conditions and during fatigue induced by repeated tetani. Muscles of young mtDNA mutator mice displayed no weakness in the rested state, but had lower force and [Ca(2+)](i) than control mice during induction of fatigue. Muscles of young mtDNA mutator mice showed decreased activities of citrate synthase and β-hydroxyacyl-coenzyme A dehydrogenase, reduced expression of cytochrome c oxidase, and decreased expression of triggers of mitochondrial biogenesis (PGC-1α, PPARα, AMPK). Muscles from end-stage mtDNA mutator mice showed weakness under resting conditions with markedly decreased tetanic [Ca(2+)](i), force per cross-sectional area and protein expression of the sarcoplasmic reticulum Ca(2+) pump (SERCA1). In conclusion, fast-twitch muscles of prematurely ageing mtDNA mutator mice display a sequence of deleterious mitochondrial-to-nucleus signalling with an initial decrease in oxidative capacity, which was not counteracted by activation of signalling to increase mitochondrial biogenesis. This was followed by severe muscle weakness in the end stage. These results have implication for normal ageing and suggest that decreased mitochondrial oxidative capacity due to a sedentary lifestyle may predispose towards muscle weakness developing later in life.

  17. Identification and characterization of cannabinoids that induce cell death through mitochondrial permeability transition in Cannabis leaf cells.

    PubMed

    Morimoto, Satoshi; Tanaka, Yumi; Sasaki, Kaori; Tanaka, Hiroyuki; Fukamizu, Tomohide; Shoyama, Yoshinari; Shoyama, Yukihiro; Taura, Futoshi

    2007-07-13

    Cannabinoids are secondary metabolites stored in capitate-sessile glands on leaves of Cannabis sativa. We discovered that cell death is induced in the leaf tissues exposed to cannabinoid resin secreted from the glands, and identified cannabichromenic acid (CBCA) and Delta(1)-tetrahydrocannabinolic acid (THCA) as unique cell death mediators from the resin. These cannabinoids effectively induced cell death in the leaf cells or suspension-cultured cells of C. sativa, whereas pretreatment with the mitochondrial permeability transition (MPT) inhibitor cyclosporin A suppressed this cell death response. Examinations using isolated mitochondria demonstrated that CBCA and THCA mediate opening of MPT pores without requiring Ca(2+) and other cytosolic factors, resulting in high amplitude mitochondrial swelling, release of mitochondrial proteins (cytochrome c and nuclease), and irreversible loss of mitochondrial membrane potential. Therefore, CBCA and THCA are considered to cause serious damage to mitochondria through MPT. The mitochondrial damage was also confirmed by a marked decrease of ATP level in cannabinoid-treated suspension cells. These features are in good accord with those of necrotic cell death, whereas DNA degradation was also observed in cannabinoid-mediated cell death. However, the DNA degradation was catalyzed by nuclease(s) released from mitochondria during MPT, indicating that this reaction was not induced via a caspase-dependent apoptotic pathway. Furthermore, the inhibition of the DNA degradation only slightly blocked the cell death induced by cannabinoids. Based on these results, we conclude that CBCA and THCA have the ability to induce necrotic cell death via mitochondrial dysfunction in the leaf cells of C. sativa.

  18. Tigecylcine induced inhibition of mitochondrial mtDNA translation may cause a lethal mitochondrial dysfunction in human.

    PubMed

    Vandecasteele, S J; Seneca, S; Smet, J; Reynders, M; De Ceulaer, J; Vanlander, A V; Van Coster, R

    2017-09-01

    A 65-year old patient developed an unexplained and ultimately lethal metabolic acidosis under prolonged treatment with tigecycline. Tigecycline is known to have a selective inhibitory effect on eukaryotic mitochondrial translation. The underlying molecular mechanisms of the metabolic acidosis in this patient were explored. OXPHOS analysis, blue native PAGE followed by in-gel activity staining in mitochondria, molecular analysis of mtDNA for genomic rearrangements and sequencing of the rRNA genes was performed on the proband's skeletal muscle. OXPHOS analysis revealed a combined deficiency of the complexes I, III, IV and V, with a preserved function of complex II (encoded by nuclear DNA), thus demonstrating a defective mtDNA translation. There were no known underlying mitochondrial genetic defects. The patient had a (m.1391T>A) variant within the 12SrRNA gene in heteroplasmy (50-60%). This patient developed an ultimately lethal mitochondrial toxicity under prolonged treatment with tigecycline, caused by a defective translation of the mtDNA. Tigecycline is known to suppress eukaryotic mitochondrial DNA translation, but until now this effect has been considered to be clinical insignificant. The observations in this patient suggest a clinical significant mitochondrial toxicity of tigecycline in this patient, and warrant further investigation. Copyright © 2017. Published by Elsevier Ltd.

  19. Mitochondrial DNA of ancient Cumanians: culturally Asian steppe nomadic immigrants with substantially more western Eurasian mitochondrial DNA lineages.

    PubMed

    Bogácsi-Szabó, Erika; Kalmár, Tibor; Csányi, Bernadett; Tömöry, Gyöngyvér; Czibula, Agnes; Priskin, Katalin; Horváth, Ferenc; Downes, Christopher Stephen; Raskó, István

    2005-10-01

    The Cumanians were originally Asian pastoral nomads who in the 13th century migrated to Hungary. We have examined mitochondrial DNA from members of the earliest Cumanian population in Hungary from two archeologically well-documented excavations and from 74 modern Hungarians from different rural locations in Hungary. Haplogroups were defined based on HVS I sequences and examinations of haplogroup-associated polymorphic sites of the protein coding region and of HVS II. To exclude contamination, some ancient DNA samples were cloned. A database was created from previously published mtDNA HVS I sequences (representing 2,615 individuals from different Asian and European populations) and 74 modem Hungarian sequences from the present study. This database was used to determine the relationships between the ancient Cumanians, modern Hungarians, and Eurasian populations and to estimate the genetic distances between these populations. We attempted to deduce the genetic trace of the migration of Cumanians. This study is the first ancient DNA characterization of an eastern pastoral nomad population that migrated into Europe. The results indicate that, while still possessing a Central Asian steppe culture, the Cumanians received a large admixture of maternal genes from more westerly populations before arriving in Hungary. A similar dilution of genetic, but not cultural, factors may have accompanied the settlement of other Asian nomads in Europe.

  20. Mitochondrial DNA disease—molecular insights and potential routes to a cure

    SciTech Connect

    Russell, Oliver; Turnbull, Doug

    2014-07-01

    Mitochondrial DNA diseases are common neurological conditions caused by mutations in the mitochondrial genome or nuclear genes responsible for its maintenance. Current treatments for these disorders are focussed on the management of the symptoms, rather than the correction of biochemical defects caused by the mutation. This review focuses on the molecular effects of mutations, the symptoms they cause and current work focusing on the development of targeted treatments for mitochondrial DNA disease. - Highlights: • We discuss several common disease causing mtDNA mutations. • We highlight recent work linking pathogenicity to deletion size and heteroplasmy. • We discuss recent advances in the development of targeted mtDNA disease treatments.

  1. Novel mutations in the TK2 gene associated with fatal mitochondrial DNA depletion myopathy.

    PubMed

    Blakely, Emma; He, Langping; Gardner, Julie L; Hudson, Gavin; Walter, John; Hughes, Imelda; Turnbull, Douglass M; Taylor, Robert W

    2008-07-01

    Mitochondrial DNA depletion syndromes are a heterogeneous group of childhood neurological disorders characterised by a quantitative abnormality of mitochondrial DNA. We describe two siblings who presented at 8 months and 14 months with myopathy, which rapidly progressed and resulted in death by respiratory failure at age 14 and 18 months, respectively. Muscle biopsy revealed marked respiratory chain defects, with real-time PCR confirming a dramatic depletion of mitochondrial DNA. Sequencing of the thymidine kinase 2 (TK2) gene revealed two, novel heterozygous mutations (p.Q87X and p.N100S) with parental DNA analysis confirming the transmission of mutated alleles.

  2. A function for the mitochondrial chaperonin Hsp60 in the structure and transmission of mitochondrial DNA nucleoids in Saccharomyces cerevisiae

    PubMed Central

    Kaufman, Brett A.; Kolesar, Jill E.; Perlman, Philip S.; Butow, Ronald A.

    2003-01-01

    The yeast mitochondrial chaperonin Hsp60 has previously been implicated in mitochondrial DNA (mtDNA) transactions: it is found in mtDNA nucleoids associated with single-stranded DNA; it binds preferentially to the template strand of active mtDNA ori sequences in vitro; and wild-type (ρ+) mtDNA is unstable in hsp60 temperature-sensitive (ts) mutants grown at the permissive temperature. Here we show that the mtDNA instability is caused by a defect in mtDNA transmission to daughter cells. Using high resolution, fluorescence deconvolution microscopy, we observe a striking alteration in the morphology of mtDNA nucleoids in ρ+ cells of an hsp60-ts mutant that suggests a defect in nucleoid division. We show that ρ− petite mtDNA consisting of active ori repeats is uniquely unstable in the hsp60-ts mutant. This instability of ori ρ− mtDNA requires transcription from the canonical promoter within the ori element. Our data suggest that the nucleoid dynamics underlying mtDNA transmission are regulated by the interaction between Hsp60 and mtDNA ori sequences. PMID:14597775

  3. Induction of Mitochondrial DNA Synthesis in Monkey Cells Infected by Simian Virus 40 and (or) Treated with Calf Serum

    PubMed Central

    Levine, Arnold J.

    1971-01-01

    Infection of confluent monolayer cultures of African green monkey kidney cells with simian virus 40 results in an enhanced synthesis of nuclear and mitochondrial DNA. This is demonstrated both by an increased rate of incorporation of [3H]thymidine into mitochondrial DNA and by detection of increased amounts of mitochondrial DNA in infected cells. With monkey BSC-1 cells, where SV40 infection does not result in a stimulation of nuclear DNA synthesis, no stimulation of mitochondrial DNA synthesis is observed. SV40 infection of mouse 3T3 cells also stimulates nuclear and mitochondrial DNA synthesis. PMID:4323784

  4. Phylogeographic Analysis of Mitochondrial DNA in Northern Asian Populations

    PubMed Central

    Derenko, Miroslava ; Malyarchuk, Boris ; Grzybowski, Tomasz ; Denisova, Galina ; Dambueva, Irina ; Perkova, Maria ; Dorzhu, Choduraa ; Luzina, Faina ; Lee, Hong Kyu ; Vanecek, Tomas ; Villems, Richard ; Zakharov, Ilia 

    2007-01-01

    To elucidate the human colonization process of northern Asia and human dispersals to the Americas, a diverse subset of 71 mitochondrial DNA (mtDNA) lineages was chosen for complete genome sequencing from the collection of 1,432 control-region sequences sampled from 18 autochthonous populations of northern, central, eastern, and southwestern Asia. On the basis of complete mtDNA sequencing, we have revised the classification of haplogroups A, D2, G1, M7, and I; identified six new subhaplogroups (I4, N1e, G1c, M7d, M7e, and J1b2a); and fully characterized haplogroups N1a and G1b, which were previously described only by the first hypervariable segment (HVS1) sequencing and coding-region restriction-fragment–length polymorphism analysis. Our findings indicate that the southern Siberian mtDNA pool harbors several lineages associated with the Late Upper Paleolithic and/or early Neolithic dispersals from both eastern Asia and southwestern Asia/southern Caucasus. Moreover, the phylogeography of the D2 lineages suggests that southern Siberia is likely to be a geographical source for the last postglacial maximum spread of this subhaplogroup to northern Siberia and that the expansion of the D2b branch occurred in Beringia ∼7,000 years ago. In general, a detailed analysis of mtDNA gene pools of northern Asians provides the additional evidence to rule out the existence of a northern Asian route for the initial human colonization of Asia. PMID:17924343

  5. Mitochondrial DNA and Y-chromosome microstructure in Tunisia.

    PubMed

    Ennafaa, Hajer; Fregel, Rosa; Khodjet-El-Khil, Houssein; González, Ana M; Mahmoudi, Hejer Abdallah El; Cabrera, Vicente M; Larruga, José M; Benammar-Elgaaïed, Amel

    2011-10-01

    Mitochondrial DNA (mtDNA) and Y-chromosome variation has been studied in Bou Omrane and Bou Saâd, two Tunisian Berber populations. In spite of their close geographic proximity, genetic distances between them were high and significant with both uniparental markers. A global analysis, including all previously studied Tunisian samples, confirmed the existence of a high female and male population structure in this country. Analyses of molecular variance analysis evidenced that this differentiation was not attributable to ethnic differences. Mantel test showed that, in all cases, Y-chromosome haplotypic distances correlated poorly with geography, whereas after excluding the more isolated samples of Bou Omrane and Bou Saâd, the mtDNA pattern of variation is significantly correlated with geography. Congruently, the N(m) ratio of males versus females pointed to a significant excess of female migration rate across localities, which could be explained by patrilocality, a common marriage system in rural Tunisia. In addition, it has been observed that cultural isolation in rural communities promotes, by the effect of genetic drift, stronger loss of diversity and larger genetic differentiation levels than those observed in urban areas as deduced from comparisons of their respective mean genetic diversity and their respective mean genetic distances among populations. It is likely that the permanent exodus from rural to urban areas will have important repercussions in the future genetic structure of this country.

  6. Mitochondrial DNA analysis of ancient sheep from Altai.

    PubMed

    Dymova, M A; Zadorozhny, A V; Mishukova, O V; Khrapov, E A; Druzhkova, A S; Trifonov, V A; Kichigin, I G; Tishkin, A A; Grushin, S P; Filipenko, M L

    2017-10-01

    A comparative analysis of the genetic diversity of ancient and modern sheep can shed light on the origin of these animals and their distribution as well as help to evaluate the role of humans at each formation stage of different sheep breeds. Here we isolated ancient DNA and performed sequencing of the mitochondrial DNA D-loop from 17 sheep bone remains (~4000-1000 years old) found in the archaeological complexes in the south of Altai (Western Siberia). The length of the sequences obtained ranged between 318 and 586 bp. The haplotype diversity and nucleotide diversity were 0.801 ± 0.081 and 0.0096 ± 0.0014 respectively. The average number of nucleotide differences was ~3.1. Nucleotide sequence analysis revealed that 15 specimens were nested within previously described A,B,C,D and E lineages and that two specimens had a basal position relative to the rest of the analyzed samples. A relatively high diversity of sheep haplotypes, including the presence of two basal haplotypes, indicates that the Altai region may have been a transport route of human migration. Further ancient DNA analysis of other specimens and deeper genome sequencing of samples with novel haplotypes is needed to better understand the demographic history of sheep in Southern Siberia. © 2017 Stichting International Foundation for Animal Genetics.

  7. Genetic variability of Taenia saginata inferred from mitochondrial DNA sequences.

    PubMed

    Rostami, Sima; Salavati, Reza; Beech, Robin N; Babaei, Zahra; Sharbatkhori, Mitra; Harandi, Majid Fasihi

    2015-04-01

    Taenia saginata is an important tapeworm, infecting humans in many parts of the world. The present study was undertaken to identify inter- and intraspecific variation of T. saginata isolated from cattle in different parts of Iran using two mitochondrial CO1 and 12S rRNA genes. Up to 105 bovine specimens of T. saginata were collected from 20 slaughterhouses in three provinces of Iran. DNA were extracted from the metacestode Cysticercus bovis. After PCR amplification, sequencing of CO1 and 12S rRNA genes were carried out and two phylogenetic analyses of the sequence data were generated by Bayesian inference on CO1 and 12S rRNA sequences. Sequence analyses of CO1 and 12S rRNA genes showed 11 and 29 representative profiles respectively. The level of pairwise nucleotide variation between individual haplotypes of CO1 gene was 0.3-2.4% while the overall nucleotide variation among all 11 haplotypes was 4.6%. For 12S rRNA sequence data, level of pairwise nucleotide variation was 0.2-2.5% and the overall nucleotide variation was determined as 5.8% among 29 haplotypes of 12S rRNA gene. Considerable genetic diversity was found in both mitochondrial genes particularly in 12S rRNA gene.

  8. Mitochondrial DNA sequences of five squamates: phylogenetic affiliation of snakes.

    PubMed

    Kumazawa, Yoshinori

    2004-04-30

    Complete or nearly complete mitochondrial DNA sequences were determined from four lizards (Western fence lizard, Warren's spinytail lizard, Terrestrial arboreal alligator lizard, and Chinese crocodile lizard) and a snake (Texas blind snake). These genomes had a typical gene organization found in those of most mammals and fishes, except for a translocation of the glutamine tRNA gene in the blind snake and a tandem duplication of the threonine and proline tRNA genes in the spinytail lizard. Although previous work showed the existence of duplicate control regions in mitochondrial DNAs of several snakes, the blind snake did not have this characteristic. Phylogenetic analyses based on different tree-building methods consistently supported that the blind snake and a colubrid snake (akamata) make a sister clade relative to all the lizard taxa from six different families. An alternative hypothesis that snakes evolved from a lineage of varanoids was not favored and nearly statistically rejected by the Kishino-Hasegawa test. It is therefore likely that the apparent similarity of the tongue structure between snakes and varanoids independently evolved and that the duplication of the control region occurred on a snake lineage after divergence of the blind snake.

  9. FGF21 is a biomarker for mitochondrial translation and mtDNA maintenance disorders

    PubMed Central

    Lehtonen, Jenni M.; Forsström, Saara; Bottani, Emanuela; Viscomi, Carlo; Baris, Olivier R.; Isoniemi, Helena; Höckerstedt, Krister; Österlund, Pia; Hurme, Mikko; Jylhävä, Juulia; Leppä, Sirpa; Markkula, Ritva; Heliö, Tiina; Mombelli, Giuliana; Uusimaa, Johanna; Laaksonen, Reijo; Laaksovirta, Hannu; Auranen, Mari; Zeviani, Massimo; Smeitink, Jan; Wiesner, Rudolf J.; Nakada, Kazuto; Isohanni, Pirjo

    2016-01-01

    Objective: To validate new mitochondrial myopathy serum biomarkers for diagnostic use. Methods: We analyzed serum FGF21 (S-FGF21) and GDF15 from patients with (1) mitochondrial diseases and (2) nonmitochondrial disorders partially overlapping with mitochondrial disorder phenotypes. We (3) did a meta-analysis of S-FGF21 in mitochondrial disease and (4) analyzed S-Fgf21 and skeletal muscle Fgf21 expression in 6 mouse models with different muscle-manifesting mitochondrial dysfunctions. Results: We report that S-FGF21 consistently increases in primary mitochondrial myopathy, especially in patients with mitochondrial translation defects or mitochondrial DNA (mtDNA) deletions (675 and 347 pg/mL, respectively; controls: 66 pg/mL, p < 0.0001 for both). This is corroborated in mice (mtDNA deletions 1,163 vs 379 pg/mL, p < 0.0001). However, patients and mice with structural respiratory chain subunit or assembly factor defects showed low induction (human 335 pg/mL, p < 0.05; mice 335 pg/mL, not significant). Overall specificities of FGF21 and GDF15 to find patients with mitochondrial myopathy were 89.3% vs 86.4%, and sensitivities 67.3% and 76.0%, respectively. However, GDF15 was increased also in a wide range of nonmitochondrial conditions. Conclusions: S-FGF21 is a specific biomarker for muscle-manifesting defects of mitochondrial translation, including mitochondrial transfer-RNA mutations and primary and secondary mtDNA deletions, the most common causes of mitochondrial disease. However, normal S-FGF21 does not exclude structural respiratory chain complex or assembly factor defects, important to acknowledge in diagnostics. Classification of evidence: This study provides Class III evidence that elevated S-FGF21 accurately distinguishes patients with mitochondrial myopathies from patients with other conditions, and FGF21 and GDF15 mitochondrial myopathy from other myopathies. PMID:27794108

  10. Radiation response of chemically derived mitochondrial DNA-deficient AG01522 human primary fibroblasts.

    PubMed

    Nieri, D; Fioramonti, M; Berardinelli, F; Leone, S; Cherubini, R; De Nadal, V; Gerardi, S; Moreno, S; Nardacci, R; Tanzarella, C; Antoccia, A

    2013-08-30

    Mitochondria are the main cellular source of Reactive Oxygen Species (ROS). Alterations of mitochondrial metabolism and consequent loss of mitochondrial membrane potential may lead to redox imbalance and in turn to DNA damage, chromosomal instability and apoptosis. On the other hand, impaired mitochondrial functions may either exacerbate the detrimental effects of geno- and cytotoxic agents or may bring beneficial cellular responses. To study the role of mitochondria within this framework, AG01522 human primary fibroblasts were incubated with the mitochondrial polymerase γ inhibitor 2',3'-dideoxycytidine (ddC), leading to mitochondrial DNA (mtDNA) depletion and to mitochondrial dysfunctions. The successful treatment toward mtDNA depletion was confirmed by Complex-IV subunit I (COX-I) immunofluorescence and western blot assays. mtDNA-depleted cells and their counterparts were ultrastructurally characterized by transmission electron microscopy. mtDNA-depleted cells showed dramatic mitochondrial alterations such as fragmentation and cristae disruption along with a reduction of the mitochondrial membrane potential and elevated levels of ROS. Despite increased ROS levels, we did not find any difference in telomere length between ddC-treated and untreated cells. The spontaneous rate of DNA double-strand breaks (DSBs) and chromosome aberrations was significantly enhanced in mtDNA-depleted cells whereas the induction of DSBs by low-Linear Energy Transfer (LET) (X-rays; 7.7keV/μm protons) and high-LET radiations (28.5keV/μm protons) did not differ when compared with normal cells. However, in irradiated cells impaired mitochondrial functions seemed to bring beneficial cellular responses to the detrimental effect of radiations. In fact, after X-irradiation mtDNA-depleted cells show less remaining unrejoined DSBs than normal cells and furthermore a lower induction of cytogenetic damage. Overall, these data show that active mitochondrial functions are required for the proper

  11. The mitochondrial outer membrane protein MDI promotes local protein synthesis and mtDNA replication.

    PubMed

    Zhang, Yi; Chen, Yong; Gucek, Marjan; Xu, Hong

    2016-05-17

    Early embryonic development features rapid nuclear DNA replication cycles, but lacks mtDNA replication. To meet the high-energy demands of embryogenesis, mature oocytes are furnished with vast amounts of mitochondria and mtDNA However, the cellular machinery driving massive mtDNA replication in ovaries remains unknown. Here, we describe a Drosophila AKAP protein, MDI that recruits a translation stimulator, La-related protein (Larp), to the mitochondrial outer membrane in ovaries. The MDI-Larp complex promotes the synthesis of a subset of nuclear-encoded mitochondrial proteins by cytosolic ribosomes on the mitochondrial surface. MDI-Larp's targets include mtDNA replication factors, mitochondrial ribosomal proteins, and electron-transport chain subunits. Lack of MDI abolishes mtDNA replication in ovaries, which leads to mtDNA deficiency in mature eggs. Targeting Larp to the mitochondrial outer membrane independently of MDI restores local protein synthesis and rescues the phenotypes of mdi mutant flies. Our work suggests that a selective translational boost by the MDI-Larp complex on the outer mitochondrial membrane might be essential for mtDNA replication and mitochondrial biogenesis during oogenesis. Published 2016. This article is a U.S. Government work and is in the public domain in the USA.

  12. Mitochondrial depolarization in yeast zygotes inhibits clonal expansion of selfish mtDNA.

    PubMed

    Karavaeva, Iuliia E; Golyshev, Sergey A; Smirnova, Ekaterina A; Sokolov, Svyatoslav S; Severin, Fedor F; Knorre, Dmitry A

    2017-04-01

    Non-identical copies of mitochondrial DNA (mtDNA) compete with each other within a cell and the ultimate variant of mtDNA present depends on their relative replication rates. Using yeast Saccharomyces cerevisiae cells as a model, we studied the effects of mitochondrial inhibitors on the competition between wild-type mtDNA and mutant selfish mtDNA in heteroplasmic zygotes. We found that decreasing mitochondrial transmembrane potential by adding uncouplers or valinomycin changes the competition outcomes in favor of the wild-type mtDNA. This effect was significantly lower in cells with disrupted mitochondria fission or repression of the autophagy-related genes ATG8, ATG32 or ATG33, implying that heteroplasmic zygotes activate mitochondrial degradation in response to the depolarization. Moreover, the rate of mitochondrially targeted GFP turnover was higher in zygotes treated with uncoupler than in haploid cells or untreated zygotes. Finally, we showed that vacuoles of zygotes with uncoupler-activated autophagy contained DNA. Taken together, our data demonstrate that mitochondrial depolarization inhibits clonal expansion of selfish mtDNA and this effect depends on mitochondrial fission and autophagy. These observations suggest an activation of mitochondria quality control mechanisms in heteroplasmic yeast zygotes. © 2017. Published by The Company of Biologists Ltd.

  13. Inter- and intraspecific mitochondrial DNA variation in North American bears (Ursus)

    USGS Publications Warehouse

    Cronin, Matthew A.; Amstrup, Steven C.; Garner, Gerald W.; Vyse, Ernest R.

    1991-01-01

    We assessed mitochondrial DNA variation in North American black bears (Ursus americanus), brown bears (Ursus arctos), and polar bears (Ursus maritimus). Divergent mitochondrial DNA haplotypes (0.05 base substitutions per nucleotide) were identified in populations of black bears from Montana and Oregon. In contrast, very similar haplotypes occur in black bears across North America. This discordance of haplotype phylogeny and geographic distribution indicates that there has been maintenance of polymorphism and considerable gene flow throughout the history of the species. Intraspecific mitochondrial DNA sequence divergence in brown bears and polar bears is lower than in black bears. The two morphological forms of U. arctos, grizzly and coastal brown bears, are not in distinct mtDNA lineages. Interspecific comparisons indicate that brown bears and polar bears share similar mitochondrial DNA (0.023 base substitutions per nucleotide) which is quite divergent (0.078 base substitutions per nucleotide) from that of black bears. High mitochondrial DNA divergence within black bears and paraphyletic relationships of brown and polar bear mitochondrial DNA indicate that intraspecific variation across species' ranges should be considered in phylogenetic analyses of mitochondrial DNA.

  14. Exploring the Effect of Asymmetric Mitochondrial DNA Introgression on Estimating Niche Divergence in Morphologically Cryptic Species

    PubMed Central

    Wielstra, Ben; Arntzen, Jan W.

    2014-01-01

    If potential morphologically cryptic species, identified based on differentiated mitochondrial DNA, express ecological divergence, this increases support for their treatment as distinct species. However, mitochondrial DNA introgression hampers the correct estimation of ecological divergence. We test the hypothesis that estimated niche divergence differs when considering nuclear DNA composition or mitochondrial DNA type as representing the true species range. We use empirical data of two crested newt species (Amphibia: Triturus) which possess introgressed mitochondrial DNA from a third species in part of their ranges. We analyze the data in environmental space by determining Fisher distances in a principal component analysis and in geographical space by determining geographical overlap of species distribution models. We find that under mtDNA guidance in one of the two study cases niche divergence is overestimated, whereas in the other it is underestimated. In the light of our results we discuss the role of estimated niche divergence in species delineation. PMID:24743746

  15. Linguistic isolates in Portugal: insights from the mitochondrial DNA pattern.

    PubMed

    Mairal, Quim; Santos, Cristina; Silva, Marina; Marques, Sofia L; Ramos, Amanda; Aluja, Maria Pilar; Amorim, Antonio; Prata, Maria João; Alvarez, Luis

    2013-12-01

    Miranda do Douro, located in the northeastern region of Portugal, has notable characteristics not only from a geographic or naturalistic point of view, but also from a cultural perspective. A remarkable one is the coexistence of two different languages: Portuguese and Mirandese, the second being an Astur-Leonese dialect. The current persistence of the Astur-Leonese dialect in this population falls on the singularity of the region: relative isolation, implying difficulties to communicate with other Portuguese regions, while the same location facilitated the establishment of social and commercial relationships with adjacent Spanish territories, origin of the Astur-Leonese language. The objective of this study was to characterize the population from Miranda through the analysis of maternal lineages in order to evaluate whether its mitochondrial DNA diversity fitted the patterns previously reported for other populations from the Iberian Peninsula. Viewing that, the entire control region of mitochondrial DNA from 121 individuals was examined. Miranda showed a haplogroup composition usual for a Western European population, in the sense that as high as 63.6% of sequences belonged to macro-haplogroup R0. Lineages ascribed to have an African (L2a and L1b) origin, were detected, but reaching an amount commonly found in Portugal. Miranda also presented a few haplogroups typically found in Jewish populations, while rarely observed in other Iberian populations. The finding can be explained by gene flow with crypto-Jew communities that since long are known to be established in the region where Miranda is located. In Miranda, both genetic and nucleotide diversities presented low values (0.9292 ± 0.0180 and 0.01101 ± 0.00614 respectively) when compared to populations from its micro-geographical framework, which constitute a sign of population isolation that certainly provided conditions for the survival of the Astur-Leonese dialect in the region. Copyright © 2013 Elsevier

  16. Mitochondrial Oxidative Stress, Mitochondrial DNA Damage and Their Role in Age-Related Vascular Dysfunction

    PubMed Central

    Mikhed, Yuliya; Daiber, Andreas; Steven, Sebastian

    2015-01-01

    The prevalence of cardiovascular diseases is significantly increased in the older population. Risk factors and predictors of future cardiovascular events such as hypertension, atherosclerosis, or diabetes are observed with higher frequency in elderly individuals. A major determinant of vascular aging is endothelial dysfunction, characterized by impaired endothelium-dependent signaling processes. Increased production of reactive oxygen species (ROS) leads to oxidative stress, loss of nitric oxide (•NO) signaling, loss of endothelial barrier function and infiltration of leukocytes to the vascular wall, explaining the low-grade inflammation characteristic for the aged vasculature. We here discuss the importance of different sources of ROS for vascular aging and their contribution to the increased cardiovascular risk in the elderly population with special emphasis on mitochondrial ROS formation and oxidative damage of mitochondrial DNA. Also the interaction (crosstalk) of mitochondria with nicotinamide adenosine dinucleotide phosphate (NADPH) oxidases is highlighted. Current concepts of vascular aging, consequences for the development of cardiovascular events and the particular role of ROS are evaluated on the basis of cell culture experiments, animal studies and clinical trials. Present data point to a more important role of oxidative stress for the maximal healthspan (healthy aging) than for the maximal lifespan. PMID:26184181

  17. Conservation of Transit Peptide-Independent Protein Import into the Mitochondrial and Hydrogenosomal Matrix

    PubMed Central

    Garg, Sriram; Stölting, Jan; Zimorski, Verena; Rada, Petr; Tachezy, Jan; Martin, William F.; Gould, Sven B.

    2015-01-01

    The origin of protein import was a key step in the endosymbiotic acquisition of mitochondria. Though the main translocon of the mitochondrial outer membrane, TOM40, is ubiquitous among organelles of mitochondrial ancestry, the transit peptides, or N-terminal targeting sequences (NTSs), recognised by the TOM complex, are not. To better understand the nature of evolutionary conservation in mitochondrial protein import, we investigated the targeting behavior of Trichomonas vaginalis hydrogenosomal proteins in Saccharomyces cerevisiae and vice versa. Hydrogenosomes import yeast mitochondrial proteins even in the absence of their native NTSs, but do not import yeast cytosolic proteins. Conversely, yeast mitochondria import hydrogenosomal proteins with and without their short NTSs. Conservation of an NTS-independent mitochondrial import route from excavates to opisthokonts indicates its presence in the eukaryote common ancestor. Mitochondrial protein import is known to entail electrophoresis of positively charged NTSs across the electrochemical gradient of the inner mitochondrial membrane. Our present findings indicate that mitochondrial transit peptides, which readily arise from random sequences, were initially selected as a signal for charge-dependent protein targeting specifically to the mitochondrial matrix. Evolutionary loss of the electron transport chain in hydrogenosomes and mitosomes lifted the selective constraints that maintain positive charge in NTSs, allowing first the NTS charge, and subsequently the NTS itself, to be lost. This resulted in NTS-independent matrix targeting, which is conserved across the evolutionary divide separating trichomonads and yeast, and which we propose is the ancestral state of mitochondrial protein import. PMID:26338186

  18. DNA polymerase gamma and mitochondrial disease: understanding the consequence of POLG mutations.

    PubMed

    Chan, Sherine S L; Copeland, William C

    2009-05-01

    DNA polymerase gamma is the only known DNA polymerase in human mitochondria and is essential for mitochondrial DNA replication and repair. It is well established that defects in mtDNA replication lead to mitochondrial dysfunction and disease. Over 160 coding variations in the gene encoding the catalytic subunit of DNA polymerase gamma (POLG) have been identified. Our group and others have characterized a number of the more common and interesting mutations, as well as those disease mutations in the DNA polymerase gamma accessory subunit. We review the results of these studies, which provide clues to the mechanisms leading to the disease state.

  19. Axonal Degeneration Is Mediated by the Mitochondrial Permeability Transition Pore

    PubMed Central

    Barrientos, Sebastian A.; Martinez, Nicolas W.; Yoo, Soonmoon; Jara, Juan S.; Zamorano, Sebastian; Hetz, Claudio; Twiss, Jeffery L.; Alvarez, Jaime; Court, Felipe A.

    2011-01-01

    Axonal degeneration is an active process that has been associated with neurodegenerative conditions triggered by mechanical, metabolic, infectious, toxic, hereditary and inflammatory stimuli. This degenerative process can cause permanent loss of function, so it represents a focus for neuroprotective strategies. Several signaling pathways are implicated in axonal degeneration, but identification of an integrative mechanism for this self-destructive process has remained elusive. Here, we show that rapid axonal degeneration triggered by distinct mechanical and toxic insults is dependent on the activation of the mitochondrial permeability transition pore (mPTP). Both pharmacological and genetic targeting of cyclophilin D, a functional component of the mPTP, protects severed axons and vincristine-treated neurons from axonal degeneration in ex vivo and in vitro mouse and rat model systems. These effects were observed in axons from both the peripheral and central nervous system. Our results suggest that the mPTP is a key effector of axonal degeneration, upon which several independent signaling pathways converge. Since axonal and synapse degeneration are increasingly considered early pathological events in neurodegeneration, our work identifies a potential target for therapeutic intervention in a wide variety of conditions that lead to loss of axons and subsequent functional impairment. PMID:21248121

  20. Aluminum as an inducer of the mitochondrial permeability transition.

    PubMed

    Toninello, A; Clari, G; Mancon, M; Tognon, G; Zatta, P

    2000-10-01

    Treatment of rat liver mitochondria with aluminum in the presence of Ca2+ results in large amplitude swelling accompanied by loss of endogenous Mg2+ and K+ and oxidation of endogenous pyridine nucleotides. The presence of cyclosporin A, ADP, bongkrekic acid, N-ethylmaleimide and dithioerythritol prevent these effects, indicating that binding of aluminum to the inner mitochondrial membrane, most likely at the level of adenine nucleotide translocase, correlates with the induction of the membrane permeability transition (MPT). Indeed, aluminum binding promotes such a perturbation at the level of ubiquinol-cytochrome c reductase, which favors the production of reactive oxygen species. These metabolites generate an oxidative stress involving two previously defined sites in equilibrium with the glutathione and pyridine nucleotides pools, the levels of which correlate with the increase in MPT induction. Although the above-described phenomena are typical of MPT, they are not paralleled by other events normally observed in response to treatment with inducers of MPT (e.g., phosphate), such as the collapse of the electrochemical gradient and the release of accumulated Ca2+ and oxidized pyridine nucleotides. Biochemical and ultrastructural observations demonstrate that aluminum induces a pore opening having a conformation intermediate between fully open and closed in a subpopulation of mitochondria. While inorganic phosphate enhances the MPT induced by ruthenium red plus a deenergizing agent, aluminum instead inhibits this phenomenon. This finding suggests the presence of a distinct binding site for aluminum differing from that involved in MPT induction.

  1. Human mitochondrial mTERF wraps around DNA through a left-handed superhelical tandem repeat.

    PubMed

    Jiménez-Menéndez, Nereida; Fernández-Millán, Pablo; Rubio-Cosials, Anna; Arnan, Carme; Montoya, Julio; Jacobs, Howard T; Bernadó, Pau; Coll, Miquel; Usón, Isabel; Solà, Maria

    2010-07-01

    The regulation of mitochondrial DNA (mtDNA) processes is slowly being characterized at a structural level. We present here crystal structures of human mitochondrial regulator mTERF, a transcription termination factor also implicated in replication pausing, in complex with double-stranded DNA oligonucleotides containing the tRNA(Leu)(UUR) gene sequence. mTERF comprises nine left-handed helical tandem repeats that form a left-handed superhelix, the Zurdo domain.

  2. Development of primers to amplify mitochondrial DNA control region of Old World porcupines (subgenus Hystrix).

    PubMed

    Trucchi, E; Gentile, G; Sbordoni, V

    2008-09-01

    Eight primers were developed for the amplification of mitochondrial DNA control region of Old world porcupines (subgenus Hystrix). Successful amplifications of low-quality DNA extracted from old (12 years old) and recent quills were performed, thus facilitating field sampling. Successful cross-species amplifications were obtained for Hystrix africaeaustralis, H. cristata and H. indica. Length and structure of mitochondrial DNA control region were analysed and its usefulness as genetic marker for interspecific and population investigation was discussed.

  3. Concise Review: Heteroplasmic Mitochondrial DNA Mutations and Mitochondrial Diseases: Toward iPSC-Based Disease Modeling, Drug Discovery, and Regenerative Therapeutics.

    PubMed

    Hatakeyama, Hideyuki; Goto, Yu-Ichi

    2016-04-01

    Mitochondria contain m