[Genetic system for maintaining the mitochondrial human genome in yeast Yarrowia lipolytica].

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Isakova, E P; Deryabina, Yu I; Velyakova, A V; Biryukova, J K; Teplova, V V; Shevelev, A B

2016-01-01

For the first time, the possibility of maintaining an intact human mitochondrial genome in a heterologous system in the mitochondria of yeast Yarrowia lipolytica is shown. A method for introducing directional changes into the structure of the mitochondrial human genome replicating in Y. lipolytica by an artificially induced ability of yeast mitochondria for homologous recombination is proposed. A method of introducing and using phenotypic selection markers for the presence or absence of defects in genes tRNA-Lys and tRNA-Leu of the mitochondrial genome is developed. The proposed system can be used to correct harmful mutations of the human mitochondrial genome associated with mitochondrial diseases and for preparative amplification of intact mitochondrial DNA with an adjusted sequence in yeast cells. The applicability of the new system for the correction of mutations in the genes of Lys- and Leu-specific tRNAs of the human mitochondrial genome associated with serious and widespread human mitochondrial diseases such as myoclonic epilepsy with lactic acidosis (MELAS) and myoclonic epilepsy with ragged-red fibers (MERRF) is shown.

Muscle biopsies from human muscle diseases with myopathic pathology reveal common alterations in mitochondrial function.

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Sunitha, Balaraju; Gayathri, Narayanappa; Kumar, Manish; Keshava Prasad, Thottethodi Subrahmanya; Nalini, Atchayaram; Padmanabhan, Balasundaram; Srinivas Bharath, Muchukunte Mukunda

2016-07-01

Muscle diseases are clinically and genetically heterogeneous and manifest as dystrophic, inflammatory and myopathic pathologies, among others. Our previous study on the cardiotoxin mouse model of myodegeneration and inflammation linked muscle pathology with mitochondrial damage and oxidative stress. In this study, we investigated whether human muscle diseases display mitochondrial changes. Muscle biopsies from muscle disease patients, represented by dysferlinopathy (dysfy) (dystrophic pathology; n = 43), polymyositis (PM) (inflammatory pathology; n = 24), and distal myopathy with rimmed vacuoles (DMRV) (distal myopathy; n = 31) were analyzed. Mitochondrial damage (ragged blue and COX-deficient fibers) was revealed in dysfy, PM, and DMRV cases by enzyme histochemistry (SDH and COX-SDH), electron microscopy (vacuolation and altered cristae) and biochemical assays (significantly increased ADP/ATP ratio). Proteomic analysis of muscle mitochondria from all three muscle diseases by isobaric tag for relative and absolute quantitation labeling and liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis demonstrated down-regulation of electron transport chain (ETC) complex subunits, assembly factors and Krebs cycle enzymes. Interestingly, 80 of the under-expressed proteins were common among the three pathologies. Assay of ETC and Krebs cycle enzyme activities validated the MS data. Mitochondrial proteins from muscle pathologies also displayed higher tryptophan (Trp) oxidation and the same was corroborated in the cardiotoxin model. Molecular modeling predicted Trp oxidation to alter the local structure of mitochondrial proteins. Our data highlight mitochondrial alterations in muscle pathologies, represented by morphological changes, altered mitochondrial proteome and protein oxidation, thereby establishing the role of mitochondrial damage in human muscle diseases. We investigated whether human muscle diseases display mitochondrial changes. Muscle biopsies

Purification, crystallization and preliminary X-ray characterization of a human mitochondrial phenylalanyl-tRNA synthetase

International Nuclear Information System (INIS)

Levin, Inna; Kessler, Naama; Moor, Nina; Klipcan, Liron; Koc, Emine; Templeton, Paul; Spremulli, Linda; Safro, Mark

2007-01-01

The expression, purification and crystallization of recombinant human mitochondrial phenylalanyl-tRNA synthetase (mitPheRS) are reported. Diffraction data were collected to 2.2 Å resolution and the mitPheRS structure was solved using the molecular-replacement method. Human monomeric mitochondrial phenylalanyl-tRNA synthetase (mitPheRS) is an enzyme that catalyzes the charging of tRNA with the cognate amino acid phenylalanine. Human mitPheRS is a chimera of the bacterial α-subunit of PheRS and the B8 domain of its β-subunit. Together, the α-subunit and the ‘RNP-domain’ (B8 domain) at the C-terminus form the minimal structural set to construct an enzyme with phenylalanylation activity. The recombinant human mitPheRS was purified to homogeneity and crystallized in complex with phenylalanine and ATP. The crystals diffracted to 2.2 Å resolution and belonged to space group P2 1 2 1 2 1 , with unit-cell parameters a = 55, b = 90, c = 96 Å

Ionizing radiation induces PI3K-dependent JNK activation for amplifying mitochondrial dysfunction in human cervical cancer cells

International Nuclear Information System (INIS)

Kim, Min Jung; Choi, Soon Young; Bae, Sang Woo; Kang, Chang Mo; Lee, Yun Sil; Lee, Su Jae

2005-01-01

Ionizing radiation is one of the most commonly used treatments for a wide variety of tumors. Exposure of cells to ionizing radiation results in the simultaneous activation or down regulation of multiple signaling pathways, which play critical role in controlling cell death and cell survival after irradiation in a cell type specific manner. The molecular mechanism by which apoptotic cell death occurs in response to ionizing radiation has been widely explored but not precisely deciphered. Therefore an improved understanding of the mechanisms involved in radiation-induced apoptosis may ultimately provide novel strategies of intervention in specific signal transduction pathways to favorably alter the therapeutic ratio in the treatment of human malignancies. The aim of our investigation was to elucidate molecular mechanisms of the mitochondrial dysfunction mediated apoptotic cell death triggered by ionizing radiation in human cervical cancer cells. We demonstrated that ionizing radiation utilizes PI3K-JNK signaling pathway for amplifying mitochondrial dysfunction and susequent apoptotic cell death: We showed that PI3K-dependent JNK activation leads to transcriptional upregulation of Fas and the phosphorylation/inactivation of Bcl-2, resulting in mitochondrial dysfunction-mediated apoptotic cell death in response to ionizing radiation

Tributyltin induces mitochondrial fission through NAD-IDH dependent mitofusin degradation in human embryonic carcinoma cells.

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Yamada, Shigeru; Kotake, Yaichiro; Nakano, Mizuho; Sekino, Yuko; Kanda, Yasunari

2015-08-01

Organotin compounds, such as tributyltin (TBT), are well-known endocrine disruptors. TBT acts at the nanomolar level through genomic pathways via the peroxisome proliferator activated receptor (PPAR)/retinoid X receptor (RXR). We recently reported that TBT inhibits cell growth and the ATP content in the human embryonic carcinoma cell line NT2/D1 via a non-genomic pathway involving NAD(+)-dependent isocitrate dehydrogenase (NAD-IDH), which metabolizes isocitrate to α-ketoglutarate. However, the molecular mechanisms by which NAD-IDH mediates TBT toxicity remain unclear. In the present study, we evaluated the effects of TBT on mitochondrial NAD-IDH and energy production. Staining with MitoTracker revealed that nanomolar TBT levels induced mitochondrial fragmentation. TBT also degraded the mitochondrial fusion proteins, mitofusins 1 and 2. Interestingly, apigenin, an inhibitor of NAD-IDH, mimicked the effects of TBT. Incubation with an α-ketoglutarate analogue partially recovered TBT-induced mitochondrial dysfunction, supporting the involvement of NAD-IDH. Our data suggest that nanomolar TBT levels impair mitochondrial quality control via NAD-IDH in NT2/D1 cells. Thus, mitochondrial function in embryonic cells could be used to assess cytotoxicity associated with metal exposure.

Prolonged decay of molecular rate estimates for metazoan mitochondrial DNA

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Martyna Molak

2015-03-01

Full Text Available Evolutionary timescales can be estimated from genetic data using the molecular clock, often calibrated by fossil or geological evidence. However, estimates of molecular rates in mitochondrial DNA appear to scale negatively with the age of the clock calibration. Although such a pattern has been observed in a limited range of data sets, it has not been studied on a large scale in metazoans. In addition, there is uncertainty over the temporal extent of the time-dependent pattern in rate estimates. Here we present a meta-analysis of 239 rate estimates from metazoans, representing a range of timescales and taxonomic groups. We found evidence of time-dependent rates in both coding and non-coding mitochondrial markers, in every group of animals that we studied. The negative relationship between the estimated rate and time persisted across a much wider range of calibration times than previously suggested. This indicates that, over long time frames, purifying selection gives way to mutational saturation as the main driver of time-dependent biases in rate estimates. The results of our study stress the importance of accounting for time-dependent biases in estimating mitochondrial rates regardless of the timescale over which they are inferred.

Analysis of mitochondrial function and localisation during human embryonic stem cell differentiation in vitro.

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Andrew B J Prowse

Full Text Available Human embryonic stem cell (hESC derivatives show promise as viable cell therapy options for multiple disorders in different tissues. Recent advances in stem cell biology have lead to the reliable production and detailed molecular characterisation of a range of cell-types. However, the role of mitochondria during differentiation has yet to be fully elucidated. Mitochondria mediate a cells response to altered energy requirements (e.g. cardiomyocyte contraction and, as such, the mitochondrial phenotype is likely to change during the dynamic process of hESC differentiation. We demonstrate that manipulating mitochondrial biogenesis alters mesendoderm commitment. To investigate mitochondrial localisation during early lineage specification of hESCs we developed a mitochondrial reporter line, KMEL2, in which sequences encoding the green fluorescent protein (GFP are targeted to the mitochondria. Differentiation of KMEL2 lines into the three germ layers showed that the mitochondria in these differentiated progeny are GFP positive. Therefore, KMEL2 hESCs facilitate the study of mitochondria in a range of cell types and, importantly, permit real-time analysis of mitochondria via the GFP tag.

Cholesterol can modulate mitochondrial aquaporin-8 expression in human hepatic cells.

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Danielli, Mauro; Capiglioni, Alejo M; Marrone, Julieta; Calamita, Giuseppe; Marinelli, Raúl A

2017-05-01

Hepatocyte mitochondrial aquaporin-8 (mtAQP8) works as a multifunctional membrane channel protein that facilitates the uptake of ammonia for its detoxification to urea as well as the mitochondrial release of hydrogen peroxide. Since early oligonucleotide microarray studies in liver of cholesterol-fed mice showed an AQP8 downregulation, we tested whether alterations of cholesterol content per se modulate mtAQP8 expression in human hepatocyte-derived Huh-7 cells. Cholesterol loading with methyl-β-cyclodextrin (mβCD):cholesterol complexes downregulated the proteolytic activation of cholesterol-responsive sterol regulatory element-binding protein (SREBP) transcriptions factors 1 and 2, and the expression of the target gene 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR). Under such conditions, mtAQP8 mRNA and protein expressions were significantly reduced. In contrast, cholesterol depletion using mβCD alone increased SREBP-1 and 2 activation and upregulated HMGCR and mtAQP8 mRNA and protein expressions. The results suggest that cholesterol can regulate transcriptionally human hepatocyte mtAQP8 expression likely via SREBPs. The functional implications of our findings are discussed. © 2017 IUBMB Life, 69(5):341-346, 2017. © 2017 International Union of Biochemistry and Molecular Biology.

Mitochondrial Toxicity in Human Pregnancy: An Update on Clinical and Experimental Approaches in the Last 10 Years

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Constanza Morén

2014-09-01

Full Text Available Mitochondrial toxicity can be one of the most dreadful consequences of exposure to a wide range of external agents including pathogens, therapeutic agents, abuse drugs, toxic gases and other harmful chemical substances. However, little is known about the effects of mitochondrial toxicity on pregnant women exposed to these agents that may exert transplacental activity and condition fetal remodeling. It has been hypothesized that mitochondrial toxicity may be involved in some adverse obstetric outcomes. In the present study, we investigated the association between exposure to mitochondrial toxic agents and pathologic conditions ranging from fertility defects, detrimental fetal development and impaired newborn health due to intra-uterine exposure. We have reviewed data from studies in human subjects to propose mechanisms of mitochondrial toxicity that could be associated with the symptoms present in both exposed pregnant and fetal patients. Since some therapeutic interventions or accidental exposure cannot be avoided, further research is needed to gain insight into the molecular pathways leading to mitochondrial toxicity during pregnancy. The ultimate objective of these studies should be to reduce the mitochondrial toxicity of these agents and establish biomarkers for gestational monitoring of harmful effects.

Purification, crystallization and preliminary X-ray characterization of a human mitochondrial phenylalanyl-tRNA synthetase

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Levin, Inna; Kessler, Naama [Department of Structural Biology, Weizmann Institute of Science, 76100 Rehovot (Israel); Moor, Nina [Institute of Chemical Biology and Fundamental Medicine, 630090 Novosibirsk (Russian Federation); Klipcan, Liron [Department of Structural Biology, Weizmann Institute of Science, 76100 Rehovot (Israel); Koc, Emine [Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA 16802 (United States); Templeton, Paul [Department Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309-0215 (United States); Spremulli, Linda [Department of Chemistry, University of North Carolina, Chapel Hill, NC 27599-3290 (United States); Safro, Mark, E-mail: mark.safro@weizmann.ac.il [Department of Structural Biology, Weizmann Institute of Science, 76100 Rehovot (Israel)

2007-09-01

The expression, purification and crystallization of recombinant human mitochondrial phenylalanyl-tRNA synthetase (mitPheRS) are reported. Diffraction data were collected to 2.2 Å resolution and the mitPheRS structure was solved using the molecular-replacement method. Human monomeric mitochondrial phenylalanyl-tRNA synthetase (mitPheRS) is an enzyme that catalyzes the charging of tRNA with the cognate amino acid phenylalanine. Human mitPheRS is a chimera of the bacterial α-subunit of PheRS and the B8 domain of its β-subunit. Together, the α-subunit and the ‘RNP-domain’ (B8 domain) at the C-terminus form the minimal structural set to construct an enzyme with phenylalanylation activity. The recombinant human mitPheRS was purified to homogeneity and crystallized in complex with phenylalanine and ATP. The crystals diffracted to 2.2 Å resolution and belonged to space group P2{sub 1}2{sub 1}2{sub 1}, with unit-cell parameters a = 55, b = 90, c = 96 Å.

Pharmacological modulation of mitochondrial calcium homeostasis.

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Arduino, Daniela M; Perocchi, Fabiana

2018-01-10

Mitochondria are pivotal organelles in calcium (Ca 2+ ) handling and signalling, constituting intracellular checkpoints for numerous processes that are vital for cell life. Alterations in mitochondrial Ca 2+ homeostasis have been linked to a variety of pathological conditions and are critical in the aetiology of several human diseases. Efforts have been taken to harness mitochondrial Ca 2+ transport mechanisms for therapeutic intervention, but pharmacological compounds that direct and selectively modulate mitochondrial Ca 2+ homeostasis are currently lacking. New avenues have, however, emerged with the breakthrough discoveries on the genetic identification of the main players involved in mitochondrial Ca 2+ influx and efflux pathways and with recent hints towards a deep understanding of the function of these molecular systems. Here, we review the current advances in the understanding of the mechanisms and regulation of mitochondrial Ca 2+ homeostasis and its contribution to physiology and human disease. We also introduce and comment on the recent progress towards a systems-level pharmacological targeting of mitochondrial Ca 2+ homeostasis. © 2018 The Authors. The Journal of Physiology © 2018 The Physiological Society.

Mitochondrial Dynamics in Type 2 Diabetes and Cancer

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Michelle Williams

2018-04-01

Full Text Available Mitochondria are bioenergetic, biosynthetic, and signaling organelles that control various aspects of cellular and organism homeostasis. Quality control mechanisms are in place to ensure maximal mitochondrial function and metabolic homeostasis at the cellular level. Dysregulation of these pathways is a common theme in human disease. In this mini-review, we discuss how alterations of the mitochondrial network influences mitochondrial function, focusing on the molecular regulators of mitochondrial dynamics (organelle’s shape and localization. We highlight similarities and critical differences in the mitochondrial network of cancer and type 2 diabetes, which may be relevant for treatment of these diseases.

Mitochondrial damage-associated molecular patterns and vascular function†

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Wenceslau, Camilla Ferreira; McCarthy, Cameron G.; Szasz, Theodora; Spitler, Kathryn; Goulopoulou, Styliani; Webb, R. Clinton

2014-01-01

Immune system activation occurs not only due to foreign stimuli, but also due to endogenous molecules. As such, endogenous molecules that are released into the circulation due to cell death and/or injury alarm the immune system that something has disturbed homeostasis and a response is needed. Collectively, these molecules are known as damage-associated molecular patterns (DAMPs). Mitochondrial DAMPs (mtDAMPs) are potent immunological activators due to the bacterial ancestry of mitochondria. Mitochondrial DAMPs are recognized by specific pattern recognition receptors of the innate immune system, some of which are expressed in the cardiovascular system. Cell death leads to release of mtDAMPs that may induce vascular changes by mechanisms that are currently not well understood. This review will focus on recently published evidence linking mtDAMPs and immune system activation to vascular dysfunction and cardiovascular disease. PMID:24569027

Current perspectives on mitochondrial inheritance in fungi

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Xu J

2015-08-01

Full Text Available Jianping Xu,1,2 He Li2 1Department of Biology, McMaster University, Hamilton, Canada; 2The Key Laboratory for Non-Wood Forest Cultivation and Conservation of the Federal Ministry of Education, Central South University of Forestry and Technology, Changsha, People’s Republic of China Abstract: The mitochondrion is an essential organelle of eukaryotes, generating the universal energy currency, adenosine triphosphate, through oxidative phosphorylation. However, aside from generation of adenosine triphosphate, mitochondria have also been found to impact a diversity of cellular functions and organ system health in humans and other eukaryotes. Thus, inheriting and maintaining functional mitochondria are essential for cell health. Due to the relative ease of conducting genetic and molecular biological experiments using fungi, they (especially the budding yeast Saccharomyces cerevisiae have been used as model organisms for investigating the patterns of inheritance and intracellular dynamics of mitochondria and mitochondrial DNA. Indeed, the diversity of mitochondrial inheritance patterns in fungi has contributed to our broad understanding of the genetic, cellular, and molecular controls of mitochondrial inheritance and their evolutionary implications. In this review, we briefly summarize the patterns of mitochondrial inheritance in fungi, describe the genes and processes involved in controlling uniparental mitochondrial DNA inheritance in sexual crosses in basidiomycete yeasts, and provide an overview of the molecular and cellular processes governing mitochondrial inheritance during asexual budding in S. cerevisiae. Together, these studies reveal that complex regulatory networks and molecular processes are involved in ensuring the transmission of healthy mitochondria to the progeny. Keywords: uniparental inheritance, biparental inheritance, mating type, actin cable, mitochore, mitochondrial partition 

Muscle mitochondrial capacity exceeds maximal oxygen delivery in humans

DEFF Research Database (Denmark)

Boushel, Robert Christopher; Gnaiger, Erich; Calbet, Jose A L

2011-01-01

Across a wide range of species and body mass a close matching exists between maximal conductive oxygen delivery and mitochondrial respiratory rate. In this study we investigated in humans how closely in-vivo maximal oxygen consumption (VO(2) max) is matched to state 3 muscle mitochondrial respira...

Mitochondrial oxidative stress in human hepatoma cells exposed to stavudine

International Nuclear Information System (INIS)

Velsor, Leonard W.; Kovacevic, Miro; Goldstein, Mark; Leitner, Heather M.; Lewis, William; Day, Brian J.

2004-01-01

The toxicity of nucleoside reverse transcriptase inhibitors (NRTIs) is linked to altered mitochondrial DNA (mtDNA) replication and subsequent disruption of cellular energetics. This manifests clinically as elevated concentrations of lactate in plasma. The mechanism(s) underlying how the changes in mtDNA replication lead to lactic acidosis remains unclear. It is hypothesized that mitochondrial oxidative stress links the changes in mtDNA replication to mitochondrial dysfunction and ensuing NRTIs toxicity. To test this hypothesis, changes in mitochondrial function, mtDNA amplification efficiency, and oxidative stress were assessed in HepG2-cultured human hepatoblasts treated with the NRTI stavudine (2',3'-didehydro-2',3'-deoxythymidine or d4T) for 48 h. d4T produced significant mitochondrial dysfunction with a 1.5-fold increase in cellular lactate to pyruvate ratios. In addition, d4T caused a dose-dependent decrease in mtDNA amplification and a correlative increase in abundance of markers of mitochondrial oxidative stress. Manganese (III) meso-tetrakis (4-benzoic acid) porphyrin, MnTBAP, a catalytic antioxidant, ameliorated or reversed d4T-induced changes in cell injury, energetics, mtDNA amplification, and mitochondrial oxidative stress. In conclusion, d4T treatment elevates mitochondrial reactive oxygen species (ROS), enhances mitochondrial oxidative stress, and contributes mechanistically to NRTI-induced toxicity. These deleterious events may be potentiated in acquired immunodeficiency syndrome (AIDS) by human immunodeficiency virus (HIV) infection itself, coinfection (e.g., viral hepatitis), aging, substance, and alcohol use

Towards a functional definition of the mitochondrial human proteome

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Mauro Fasano

2016-03-01

Full Text Available The mitochondrial human proteome project (mt-HPP was initiated by the Italian HPP group as a part of both the chromosome-centric initiative (C-HPP and the “biology and disease driven” initiative (B/D-HPP. In recent years several reports highlighted how mitochondrial biology and disease are regulated by specific interactions with non-mitochondrial proteins. Thus, it is of great relevance to extend our present view of the mitochondrial proteome not only to those proteins that are encoded by or transported to mitochondria, but also to their interactors that take part in mitochondria functionality. Here, we propose a graphical representation of the functional mitochondrial proteome by retrieving mitochondrial proteins from the NeXtProt database and adding to the network their interactors as annotated in the IntAct database. Notably, the network may represent a reference to map all the proteins that are currently being identified in mitochondrial proteomics studies.

Oxidative stress induced by palytoxin in human keratinocytes is mediated by a H+-dependent mitochondrial pathway

International Nuclear Information System (INIS)

Pelin, Marco; Ponti, Cristina; Sosa, Silvio; Gibellini, Davide; Florio, Chiara; Tubaro, Aurelia

2013-01-01

In the last decades, massive blooms of palytoxin (PLTX)-producing Ostreopsis cf. ovata have been observed along Mediterranean coasts, usually associated to human respiratory and cutaneous problems. At the molecular level, PLTX induces a massive intracellular Na + influx due to the transformation of Na + /K + ATPase in a cationic channel. Recently, we have demonstrated that Na + overload is the crucial step in mediating overproduction of reactive oxygen species (ROS) and cell death in human HaCaT keratinocytes, tentatively explaining PLTX-induced skin irritant effects. In the present study the molecular mechanisms of ROS production induced by PLTX-mediated Na + intracellular overload have been investigated. In HaCaT cells, PLTX exposure caused accumulation of superoxide anion, but not of nitric oxide or peroxynitrite/hydroxyl radicals. Even if RT-PCR and western blot analysis revealed an early NOX-2 and iNOS gene and protein over-expressions, their active involvement seemed to be only partial since selective inhibitors did not completely reduce O 2 − production. A significant role of other enzymes (COX-1, COX-2, XO) was not evidenced. Nigericin, that counteracts Na + -mediated H + -imbalance, dissipating ΔpH across mitochondrial inner membrane, and the uncouplers DNP significantly reduced O 2 − production. These inhibitions were synergistic when co-exposed with complex-I inhibitor rotenone. These results suggest a novel mechanism of O 2 − production induced by PLTX-mediated ionic imbalance. Indeed, the H + intracellular overload that follows PLTX-induced intracellular Na + accumulation, could enhance ΔpH across mitochondrial inner membrane, that seems to be the driving force for O 2 − production by reversing mitochondrial electron transport. Highlights: ► PLTX induces superoxide (O 2 − ) production by reversing mitochondrial transport chain. ► The mechanism of O 2 − production is dependent on PLTX-induced ionic imbalance. ► The results led to the

Optimizing the measurement of mitochondrial protein synthesis in human skeletal muscle.

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Burd, Nicholas A; Tardif, Nicolas; Rooyackers, Olav; van Loon, Luc J C

2015-01-01

The measurement of mitochondrial protein synthesis after food ingestion, contractile activity, and/or disease is often used to provide insight into skeletal muscle adaptations that occur in the longer term. Studies have shown that protein ingestion stimulates mitochondrial protein synthesis in human skeletal muscle. Minor differences in the stimulation of mitochondrial protein synthesis occur after a single bout of resistance or endurance exercise. There appear to be no measurable differences in mitochondrial protein synthesis between critically ill patients and aged-matched controls. However, the mitochondrial protein synthetic response is reduced at a more advanced age. In this paper, we discuss the challenges involved in the measurement of human skeletal muscle mitochondrial protein synthesis rates based on stable isotope amino acid tracer methods. Practical guidelines are discussed to improve the reliability of the measurement of mitochondrial protein synthesis rates. The value of the measurement of mitochondrial protein synthesis after a single meal or exercise bout on the prediction of the longer term skeletal muscle mass and performance outcomes in both the healthy and disease populations requires more work, but we emphasize that the measurements need to be reliable to be of any value to the field.

Rapid Molecular Identification of Human Taeniid Cestodes by Pyrosequencing Approach

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Thanchomnang, Tongjit; Tantrawatpan, Chairat; Intapan, Pewpan M.; Sanpool, Oranuch; Janwan, Penchom; Lulitanond, Viraphong; Tourtip, Somjintana; Yamasaki, Hiroshi; Maleewong, Wanchai

2014-01-01

Taenia saginata, T. solium, and T. asiatica are causative agents of taeniasis in humans. The difficulty of morphological identification of human taeniids can lead to misdiagnosis or confusion. To overcome this problem, several molecular methods have been developed, but use of these tends to be time-consuming. Here, a rapid and high-throughput pyrosequencing approach was developed for the identification of three human taeniids originating from various countries. Primers targeting the mitochondrial cytochrome c oxidase subunit 1 (cox1) gene of the three Taenia species were designed. Variations in a 26-nucleotide target region were used for identification. The reproducibility and accuracy of the pyrosequencing technology was confirmed by Sanger sequencing. This technique will be a valuable tool to distinguish between sympatric human taeniids that occur in Thailand, Asia and Pacific countries. This method could potentially be used for the molecular identification of the taeniid species that might be associated with suspicious cysts and lesions, or cyst residues in humans or livestock at the slaughterhouse. PMID:24945530

Endangered species: mitochondrial DNA loss as a mechanism of human disease.

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Herrera, Alan; Garcia, Iraselia; Gaytan, Norma; Jones, Edith; Maldonado, Alicia; Gilkerson, Robert

2015-06-01

Human mitochondrial DNA (mtDNA) is a small maternally inherited DNA, typically present in hundreds of copies in a single human cell. Thus, despite its small size, the mitochondrial genome plays a crucial role in the metabolic homeostasis of the cell. Our understanding of mtDNA genotype-phenotype relationships is derived largely from studies of the classical mitochondrial neuromuscular diseases, in which mutations of mtDNA lead to compromised mitochondrial bioenergetic function, with devastating pathological consequences. Emerging research suggests that loss, rather than mutation, of mtDNA plays a major role across a range of prevalent human diseases, including diabetes mellitus, cardiovascular disease, and aging. Here, we examine the 'rules' of mitochondrial genetics and function, the clinical settings in which loss of mtDNA is an emerging pathogenic mechanism, and explore mtDNA damage and its consequences for the organellar network and cell at large. As extranuclear genetic material arrayed throughout the cell to support metabolism, mtDNA is increasingly implicated in a host of disease conditions, opening a range of exciting questions regarding mtDNA and its role in cellular homeostasis.

Molecular epidemiology of human oral Chagas disease outbreaks in Colombia.

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Juan David Ramírez

Full Text Available BACKGROUND: Trypanosoma cruzi, the causative agent of Chagas disease, displays significant genetic variability revealed by six Discrete Typing Units (TcI-TcVI. In this pathology, oral transmission represents an emerging epidemiological scenario where different outbreaks associated to food/beverages consumption have been reported in Argentina, Bolivia, Brazil, Ecuador and Venezuela. In Colombia, six human oral outbreaks have been reported corroborating the importance of this transmission route. Molecular epidemiology of oral outbreaks is barely known observing the incrimination of TcI, TcII, TcIV and TcV genotypes. METHODOLOGY AND PRINCIPAL FINDINGS: High-throughput molecular characterization was conducted performing MLMT (Multilocus Microsatellite Typing and mtMLST (mitochondrial Multilocus Sequence Typing strategies on 50 clones from ten isolates. Results allowed observing the occurrence of TcI, TcIV and mixed infection of distinct TcI genotypes. Thus, a majority of specific mitochondrial haplotypes and allelic multilocus genotypes associated to the sylvatic cycle of transmission were detected in the dataset with the foreseen presence of mitochondrial haplotypes and allelic multilocus genotypes associated to the domestic cycle of transmission. CONCLUSIONS: These findings suggest the incrimination of sylvatic genotypes in the oral outbreaks occurred in Colombia. We observed patterns of super-infection and/or co-infection with a tailored association with the severe forms of myocarditis in the acute phase of the disease. The transmission dynamics of this infection route based on molecular epidemiology evidence was unraveled and the clinical and biological implications are discussed.

Increased intrinsic mitochondrial function in humans with mitochondrial haplogroup H

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Larsen, Steen; Díez-Sánchez, Carmen; Rabøl, Rasmus

2014-01-01

and determined their mitochondrial haplogroup, mitochondrial oxidative phosphorylation capacity (OXPHOS), mitochondrial content (citrate synthase (CS)) and VO2max. Intrinsic mitochondrial function is calculated as mitochondrial OXPHOS capacity divided by mitochondrial content (CS). Haplogroup H showed a 30......% higher intrinsic mitochondrial function compared with the other haplo group U. There was no relationship between haplogroups and VO2max. In skeletal muscle from men with mitochondrial haplogroup H, an increased intrinsic mitochondrial function is present....

Mitochondrial mass is inversely correlated to complete lipid oxidation in human myotubes

DEFF Research Database (Denmark)

Gaster, Michael

2011-01-01

Exercise increases while physical inactivity decrease mitochondrial content and oxidative capacity of skeletal muscles in vivo. It is unknown whether mitochondrial mass and substrate oxidation are related in non-contracting skeletal muscle. Mitochondrial mass, ATP, ADP, AMP, glucose and lipid......, basal glucose oxidation and incomplete lipid oxidation were significantly increased while complete lipid oxidation was lower. Mitochondrial mass was not correlated to glucose oxidation or incomplete lipid oxidation in human myotubes but inversely correlated to complete lipid oxidation. Thus within...... a stable energetic background, an increased mitochondrial mass in human myotubes was not positive correlated to an increased substrate oxidation as expected from skeletal muscles in vivo but surprisingly with a reduced complete lipid oxidation....

Distinct patterns of mitochondrial genome diversity in bonobos (Pan paniscus and humans

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Zsurka Gábor

2010-09-01

Full Text Available Abstract Background We have analyzed the complete mitochondrial genomes of 22 Pan paniscus (bonobo, pygmy chimpanzee individuals to assess the detailed mitochondrial DNA (mtDNA phylogeny of this close relative of Homo sapiens. Results We identified three major clades among bonobos that separated approximately 540,000 years ago, as suggested by Bayesian analysis. Incidentally, we discovered that the current reference sequence for bonobo likely is a hybrid of the mitochondrial genomes of two distant individuals. When comparing spectra of polymorphic mtDNA sites in bonobos and humans, we observed two major differences: (i Of all 31 bonobo mtDNA homoplasies, i.e. nucleotide changes that occurred independently on separate branches of the phylogenetic tree, 13 were not homoplasic in humans. This indicates that at least a part of the unstable sites of the mitochondrial genome is species-specific and difficult to be explained on the basis of a mutational hotspot concept. (ii A comparison of the ratios of non-synonymous to synonymous changes (dN/dS among polymorphic positions in bonobos and in 4902 Homo sapiens mitochondrial genomes revealed a remarkable difference in the strength of purifying selection in the mitochondrial genes of the F0F1-ATPase complex. While in bonobos this complex showed a similar low value as complexes I and IV, human haplogroups displayed 2.2 to 7.6 times increased dN/dS ratios when compared to bonobos. Conclusions Some variants of mitochondrially encoded subunits of the ATPase complex in humans very likely decrease the efficiency of energy conversion leading to production of extra heat. Thus, we hypothesize that the species-specific release of evolutionary constraints for the mitochondrial genes of the proton-translocating ATPase is a consequence of altered heat homeostasis in modern humans.

Mitochondrial DNA diagnosis for taeniasis and cysticercosis.

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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.

Mitochondrial iron-sulfur cluster biogenesis from molecular understanding to clinical disease

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Alfadhel, Majid; Nashabat, Marwan; Ali, Qais Abu; Hundallah, Khalid

2017-01-01

Iron–sulfur clusters (ISCs) are known to play a major role in various protein functions. Located in the mitochondria, cytosol, endoplasmic reticulum and nucleus, they contribute to various core cellular functions. Until recently, only a few human diseases related to mitochondrial ISC biogenesis defects have been described. Such diseases include Friedreich ataxia, combined oxidative phosphorylation deficiency 19, infantile complex II/III deficiency defect, hereditary myopathy with lactic acidosis and mitochondrial muscle myopathy, lipoic acid biosynthesis defects, multiple mitochondrial dysfunctions syndromes and non ketotic hyperglycinemia due to glutaredoxin 5 gene defect. Disorders of mitochondrial import, export and translation, including sideroblastic anemia with ataxia, EVEN-PLUS syndrome and mitochondrial complex I deficiency due to nucleotide-binding protein-like protein gene defect, have also been implicated in ISC biogenesis defects. With advances in next generation sequencing technologies, more disorders related to ISC biogenesis defects are expected to be elucidated. In this article, we aim to shed the light on mitochondrial ISC biogenesis, related proteins and their function, pathophysiology, clinical phenotypes of related disorders, diagnostic approach, and future implications. PMID:28064324

Molecular identification of Echinococcus granulosus on the Tibetan Plateau using mitochondrial DNA markers.

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Hu, D; Song, X; Wang, N; Zhong, X; Wang, J; Liu, T; Jiang, Z; Dawa, T; Gu, X; Peng, X; Yang, G

2015-10-30

Cystic echinococcosis (CE) is an important worldwide zoonotic disease that causes large economic losses and human suffering. Echinococcus granulosus, the causative agent of CE, exhibits different genotypes in different locations. In order to identify its genotypes and analyze its genetic structure on the Tibetan Plateau, we collected 72 hydatid cysts from different intermediate hosts and amplified and sequenced their mitochondrial cytochrome c oxidase subunit 2 (cox2) genes. Seventy isolates were identified as the E. granulosus G1 genotype, while two isolates belonged to the G6 genotype. There were 18 haplotypes among the 70 E. granulosus isolates, which exhibited a star-like network pattern and shared a common haplotype (H1). There was little difference between geographical sub-populations. Our results suggest that a recent E. granulosus population expansion occurred on the Tibetan Plateau, suggesting that E. granulosus was introduced into China. This study increases the basic molecular data needed for the molecular diagnosis, epidemiology, prevention, and control of Echinococcus diseases.

Yeast as a system for modeling mitochondrial disease mechanisms and discovering therapies

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Jean-Paul Lasserre

2015-06-01

Full Text Available Mitochondrial diseases are severe and largely untreatable. Owing to the many essential processes carried out by mitochondria and the complex cellular systems that support these processes, these diseases are diverse, pleiotropic, and challenging to study. Much of our current understanding of mitochondrial function and dysfunction comes from studies in the baker's yeast Saccharomyces cerevisiae. Because of its good fermenting capacity, S. cerevisiae can survive mutations that inactivate oxidative phosphorylation, has the ability to tolerate the complete loss of mitochondrial DNA (a property referred to as ‘petite-positivity’, and is amenable to mitochondrial and nuclear genome manipulation. These attributes make it an excellent model system for studying and resolving the molecular basis of numerous mitochondrial diseases. Here, we review the invaluable insights this model organism has yielded about diseases caused by mitochondrial dysfunction, which ranges from primary defects in oxidative phosphorylation to metabolic disorders, as well as dysfunctions in maintaining the genome or in the dynamics of mitochondria. Owing to the high level of functional conservation between yeast and human mitochondrial genes, several yeast species have been instrumental in revealing the molecular mechanisms of pathogenic human mitochondrial gene mutations. Importantly, such insights have pointed to potential therapeutic targets, as have genetic and chemical screens using yeast.

Manganese induces mitochondrial dynamics impairment and apoptotic cell death: a study in human Gli36 cells.

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Alaimo, Agustina; Gorojod, Roxana M; Miglietta, Esteban A; Villarreal, Alejandro; Ramos, Alberto J; Kotler, Mónica L

2013-10-25

Manganese (Mn) is an essential trace element due to its participation in many physiological processes. However, overexposure to this metal leads to a neurological disorder known as Manganism whose clinical manifestations and molecular mechanisms resemble Parkinson's disease. Several lines of evidence implicate astrocytes as an early target of Mn neurotoxicity being the mitochondria the most affected organelles. The aim of this study was to investigate the possible mitochondrial dynamics alterations in Mn-exposed human astrocytes. Therefore, we employed Gli36 cells which express the astrocytic markers GFAP and S100B. We demonstrated that Mn triggers the mitochondrial apoptotic pathway revealed by increased Bax/Bcl-2 ratio, by the loss of mitochondrial membrane potential and by caspase-9 activation. This apoptotic program may be in turn responsible of caspase-3/7 activation, PARP-1 cleavage, chromatin condensation and fragmentation. In addition, we determined that Mn induces deregulation in mitochondria-shaping proteins (Opa-1, Mfn-2 and Drp-1) expression levels in parallel with the disruption of the mitochondrial network toward to an exacerbated fragmentation. Since mitochondrial dynamics is altered in several neurodegenerative diseases, these proteins could become future targets to be considered in Manganism treatment. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Human skeletal muscle mitochondrial capacity.

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Rasmussen, U F; Rasmussen, H N

2000-04-01

Under aerobic work, the oxygen consumption and major ATP production occur in the mitochondria and it is therefore a relevant question whether the in vivo rates can be accounted for by mitochondrial capacities measured in vitro. Mitochondria were isolated from human quadriceps muscle biopsies in yields of approximately 45%. The tissue content of total creatine, mitochondrial protein and different cytochromes was estimated. A number of activities were measured in functional assays of the mitochondria: pyruvate, ketoglutarate, glutamate and succinate dehydrogenases, palmitoyl-carnitine respiration, cytochrome oxidase, the respiratory chain and the ATP synthesis. The activities involved in carbohydrate oxidation could account for in vivo oxygen uptakes of 15-16 mmol O2 min-1 kg-1 or slightly above the value measured at maximal work rates in the knee-extensor model of Saltin and co-workers, i.e. without limitation from the cardiac output. This probably indicates that the maximal oxygen consumption of the muscle is limited by the mitochondrial capacities. The in vitro activities of fatty acid oxidation corresponded to only 39% of those of carbohydrate oxidation. The maximal rate of free energy production from aerobic metabolism of glycogen was calculated from the mitochondrial activities and estimates of the DeltaG or ATP hydrolysis and the efficiency of the actin-myosin reaction. The resultant value was 20 W kg-1 or approximately 70% of the maximal in vivo work rates of which 10-20% probably are sustained by the anaerobic ATP production. The lack of aerobic in vitro ATP synthesis might reflect termination of some critical interplay between cytoplasm and mitochondria.

Continued colonization of the human genome by mitochondrial DNA.

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Miria Ricchetti

2004-09-01

Full Text Available Integration of mitochondrial DNA fragments into nuclear chromosomes (giving rise to nuclear DNA sequences of mitochondrial origin, or NUMTs is an ongoing process that shapes nuclear genomes. In yeast this process depends on double-strand-break repair. Since NUMTs lack amplification and specific integration mechanisms, they represent the prototype of exogenous insertions in the nucleus. From sequence analysis of the genome of Homo sapiens, followed by sampling humans from different ethnic backgrounds, and chimpanzees, we have identified 27 NUMTs that are specific to humans and must have colonized human chromosomes in the last 4-6 million years. Thus, we measured the fixation rate of NUMTs in the human genome. Six such NUMTs show insertion polymorphism and provide a useful set of DNA markers for human population genetics. We also found that during recent human evolution, Chromosomes 18 and Y have been more susceptible to colonization by NUMTs. Surprisingly, 23 out of 27 human-specific NUMTs are inserted in known or predicted genes, mainly in introns. Some individuals carry a NUMT insertion in a tumor-suppressor gene and in a putative angiogenesis inhibitor. Therefore in humans, but not in yeast, NUMT integrations preferentially target coding or regulatory sequences. This is indeed the case for novel insertions associated with human diseases and those driven by environmental insults. We thus propose a mutagenic phenomenon that may be responsible for a variety of genetic diseases in humans and suggest that genetic or environmental factors that increase the frequency of chromosome breaks provide the impetus for the continued colonization of the human genome by mitochondrial DNA.

Mitochondrial function in human skeletal muscle following high-altitude exposure

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Jacobs, Robert A; Boushel, Robert; Wright-Paradis, Cynthia

2013-01-01

Studies regarding mitochondrial modifications in human skeletal muscle following acclimatization to high altitude are conflicting, and these inconsistencies may be due to the prevalence of representing mitochondrial function through static and isolated measurements of specific mitochondrial...... characteristics. The aim of this study, therefore, was to investigate mitochondrial function in response to high-altitude acclimatization through measurements of respiratory control in the vastus lateralis muscle. Skeletal muscle biopsies were obtained from 10 lowland natives prior to and again after a total of 9......-11 days of exposure to 4559 m. High-resolution respirometry was performed on the muscle samples to compare respiratory chain function and respiratory capacities. Respirometric analysis revealed that mitochondrial function was largely unaffected, because high-altitude exposure did not affect the capacity...

Rapid molecular identification of human taeniid cestodes by pyrosequencing approach.

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Tongjit Thanchomnang

Full Text Available Taenia saginata, T. solium, and T. asiatica are causative agents of taeniasis in humans. The difficulty of morphological identification of human taeniids can lead to misdiagnosis or confusion. To overcome this problem, several molecular methods have been developed, but use of these tends to be time-consuming. Here, a rapid and high-throughput pyrosequencing approach was developed for the identification of three human taeniids originating from various countries. Primers targeting the mitochondrial cytochrome c oxidase subunit 1 (cox1 gene of the three Taenia species were designed. Variations in a 26-nucleotide target region were used for identification. The reproducibility and accuracy of the pyrosequencing technology was confirmed by Sanger sequencing. This technique will be a valuable tool to distinguish between sympatric human taeniids that occur in Thailand, Asia and Pacific countries. This method could potentially be used for the molecular identification of the taeniid species that might be associated with suspicious cysts and lesions, or cyst residues in humans or livestock at the slaughterhouse.

Three dimensional reconstruction of the human skeletal muscle mitochondrial network as a tool to assess mitochondrial content and structural organization

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Dahl, Rannvá; Larsen, Steen; Dohlmann, Tine L

2015-01-01

a method to visualize mitochondrial networks in high resolution and assess mitochondrial volume. Methods: Confocal fluorescence microscopy imaging of mitochondrial network stains in human vastus lateralis single muscle fibers and, focused ion beam scanning electron microscopy (FIB/SEM) imaging, combined...... mitochondrial dynamics in response to life-style interventions and/or in certain pathologies. Our results question the classification of mitochondria into subsarcolemmal and intermyofibrillar pools, since they are physically interconnected. This article is protected by copyright. All rights reserved....

Enhanced oxidative stress and aberrant mitochondrial biogenesis in human neuroblastoma SH-SY5Y cells during methamphetamine induced apoptosis

International Nuclear Information System (INIS)

Wu, C.-W.; Ping, Y.-H.; Yen, J.-C.; Chang, C.-Y.; Wang, S.-F.; Yeh, C.-L.; Chi, C.-W.; Lee, H.-C.

2007-01-01

Methamphetamine (METH) is an abused drug that may cause psychiatric and neurotoxic damage, including degeneration of monoaminergic terminals and apoptosis of non-monoaminergic cells in Brain. The cellular and molecular mechanisms underlying these METH-induced neurotoxic effects remain to be clarified. In this study, we performed a time course assessment to investigate the effects of METH on intracellular oxidative stress and mitochondrial alterations in a human dopaminergic neuroblastoma SH-SY5Y cell line. We characterized that METH induces a temporal sequence of several cellular events including, firstly, a decrease in mitochondrial membrane potential within 1 h of the METH treatment, secondly, an extensive decline in mitochondrial membrane potential and increase in the level of reactive oxygen species (ROS) after 8 h of the treatment, thirdly, an increase in mitochondrial mass after the drug treatment for 24 h, and finally, a decrease in mtDNA copy number and mitochondrial proteins per mitochondrion as well as the occurrence of apoptosis after 48 h of the treatment. Importantly, vitamin E attenuated the METH-induced increases in intracellular ROS level and mitochondrial mass, and prevented METH-induced cell death. Our observations suggest that enhanced oxidative stress and aberrant mitochondrial biogenesis may play critical roles in METH-induced neurotoxic effects

Molecular approaches to Taenia asiatica.

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Jeon, Hyeong-Kyu; Eom, Keeseon S

2013-02-01

Taenia solium, T. saginata, and T. asiatica are taeniid tapeworms that cause taeniasis in humans and cysticercosis in intermediate host animals. Taeniases remain an important public health concerns in the world. Molecular diagnostic methods using PCR assays have been developed for rapid and accurate detection of human infecting taeniid tapeworms, including the use of sequence-specific DNA probes, PCR-RFLP, and multiplex PCR. More recently, DNA diagnosis using PCR based on histopathological specimens such as 10% formalin-fixed paraffin-embedded and stained sections mounted on slides has been applied to cestode infections. The mitochondrial gene sequence is believed to be a very useful molecular marker for not only studying evolutionary relationships among distantly related taxa, but also for investigating the phylo-biogeography of closely related species. The complete sequence of the human Taenia tapeworms mitochondrial genomes were determined, and its organization and structure were compared to other human-tropic Taenia tapeworms for which complete mitochondrial sequence data were available. The multiplex PCR assay with the Ta4978F, Ts5058F, Tso7421F, and Rev7915 primers will be useful for differential diagnosis, molecular characterization, and epidemiological surveys of human Taenia tapeworms.

Molecular Approaches to Taenia asiatica

Science.gov (United States)

Jeon, Hyeong-Kyu

2013-01-01

Taenia solium, T. saginata, and T. asiatica are taeniid tapeworms that cause taeniasis in humans and cysticercosis in intermediate host animals. Taeniases remain an important public health concerns in the world. Molecular diagnostic methods using PCR assays have been developed for rapid and accurate detection of human infecting taeniid tapeworms, including the use of sequence-specific DNA probes, PCR-RFLP, and multiplex PCR. More recently, DNA diagnosis using PCR based on histopathological specimens such as 10% formalin-fixed paraffin-embedded and stained sections mounted on slides has been applied to cestode infections. The mitochondrial gene sequence is believed to be a very useful molecular marker for not only studying evolutionary relationships among distantly related taxa, but also for investigating the phylo-biogeography of closely related species. The complete sequence of the human Taenia tapeworms mitochondrial genomes were determined, and its organization and structure were compared to other human-tropic Taenia tapeworms for which complete mitochondrial sequence data were available. The multiplex PCR assay with the Ta4978F, Ts5058F, Tso7421F, and Rev7915 primers will be useful for differential diagnosis, molecular characterization, and epidemiological surveys of human Taenia tapeworms. PMID:23467738

Biomarkers of mitochondrial content in skeletal muscle of healthy young human subjects

DEFF Research Database (Denmark)

Larsen, Steen; Nielsen, Joachim; Hansen, Christina Neigaard

2012-01-01

Key points  Several biochemical measures of mitochondrial components are used as biomarkers of mitochondrial content and muscle oxidative capacity. However, no studies have validated these surrogates against a morphological measure of mitochondrial content in human subjects.  The most commonly used...... markers (citrate synthase activity, cardiolipin content, mitochondrial DNA content (mtDNA), complex I-V protein, and complex I-IV activity) were correlated with a measure of mitochondrial content (transmission electron microscopy) and muscle oxidative capacity (respiration in permeabilized fibres......).  Cardiolipin content followed by citrate synthase activity and complex I activity were the biomarkers showing the strongest association with mitochondrial content.  mtDNA was found to be a poor biomarker of mitochondrial content.  Complex IV activity was closely associated with mitochondrial oxidative...

Involvement of the mitochondrial compartment in human NCL fibroblasts

International Nuclear Information System (INIS)

Pezzini, Francesco; Gismondi, Floriana; Tessa, Alessandra; Tonin, Paola; Carrozzo, Rosalba; Mole, Sara E.; Santorelli, Filippo M.; Simonati, Alessandro

2011-01-01

Highlights: ► Mitochondrial reticulum fragmentation occurs in human CLN1 and CLN6 fibroblasts. ► Likewise mitochondrial shift-to periphery and decreased mitochondrial density are seen. ► Enhanced caspase-mediated apoptosis occurs following STS treatment in CLN1 fibroblasts. -- Abstract: Neuronal ceroid lipofuscinosis (NCL) are a group of progressive neurodegenerative disorders of childhood, characterized by the endo-lysosomal storage of autofluorescent material. Impaired mitochondrial function is often associated with neurodegeneration, possibly related to the apoptotic cascade. In this study we investigated the possible effects of lysosomal accumulation on the mitochondrial compartment in the fibroblasts of two NCL forms, CLN1 and CLN6. Fragmented mitochondrial reticulum was observed in all cells by using the intravital fluorescent marker Mitotracker, mainly in the perinuclear region. This was also associated with intense signal from the lysosomal markers Lysotracker and LAMP2. Likewise, mitochondria appeared to be reduced in number and shifted to the cell periphery by electron microscopy; moreover the mitochondrial markers VDCA and COX IV were reduced following quantitative Western blot analysis. Whilst there was no evidence of increased cell death under basal condition, we observed a significant increase in apoptotic nuclei following Staurosporine treatment in CLN1 cells only. In conclusion, the mitochondrial compartment is affected in NCL fibroblasts invitro, and CLN1 cells seem to be more vulnerable to the negative effects of stressed mitochondrial membrane than CLN6 cells.

Ketamine Causes Mitochondrial Dysfunction in Human Induced Pluripotent Stem Cell-Derived Neurons

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Ito, Hiroyuki; Uchida, Tokujiro; Makita, Koshi

2015-01-01

Purpose Ketamine toxicity has been demonstrated in nonhuman mammalian neurons. To study the toxic effect of ketamine on human neurons, an experimental model of cultured neurons from human induced pluripotent stem cells (iPSCs) was examined, and the mechanism of its toxicity was investigated. Methods Human iPSC-derived dopaminergic neurons were treated with 0, 20, 100 or 500 μM ketamine for 6 and 24 h. Ketamine toxicity was evaluated by quantification of caspase 3/7 activity, reactive oxygen species (ROS) production, mitochondrial membrane potential, ATP concentration, neurotransmitter reuptake activity and NADH/NAD+ ratio. Mitochondrial morphological change was analyzed by transmission electron microscopy and confocal microscopy. Results Twenty-four-hour exposure of iPSC-derived neurons to 500 μM ketamine resulted in a 40% increase in caspase 3/7 activity (P ketamine (100 μM) decreased the ATP level (22%, P ketamine concentration, which suggests that mitochondrial dysfunction preceded ROS generation and caspase activation. Conclusions We established an in vitro model for assessing the neurotoxicity of ketamine in iPSC-derived neurons. The present data indicate that the initial mitochondrial dysfunction and autophagy may be related to its inhibitory effect on the mitochondrial electron transport system, which underlies ketamine-induced neural toxicity. Higher ketamine concentration can induce ROS generation and apoptosis in human neurons. PMID:26020236

Targeted impairment of thymidine kinase 2 expression in cells induces mitochondrial DNA depletion and reveals molecular mechanisms of compensation of mitochondrial respiratory activity

International Nuclear Information System (INIS)

Villarroya, Joan; Lara, Mari-Carmen; Dorado, Beatriz; Garrido, Marta; Garcia-Arumi, Elena; Meseguer, Anna; Hirano, Michio; Vila, Maya R.

2011-01-01

Highlights: → We impaired TK2 expression in Ost TK1 - cells via siRNA-mediated interference (TK2 - ). → TK2 impairment caused severe mitochondrial DNA (mtDNA) depletion in quiescent cells. → Despite mtDNA depletion, TK2 - cells show high cytochrome oxidase activity. → Depletion of mtDNA occurs without imbalance in the mitochondrial dNTP pool. → Nuclear-encoded ENT1, DNA-pol γ, TFAM and TP gene expression is lowered in TK2 - cells. -- Abstract: The mitochondrial DNA (mtDNA) depletion syndrome comprises a clinically heterogeneous group of diseases characterized by reductions of the mtDNA abundance, without associated point mutations or rearrangements. We have developed the first in vitro model to study of mtDNA depletion due to reduced mitochondrial thymidine kinase 2 gene (TK2) expression in order to understand the molecular mechanisms involved in mtDNA depletion syndrome due to TK2 mutations. Small interfering RNA targeting TK2 mRNA was used to decrease TK2 expression in Ost TK1 - cells, a cell line devoid of endogenous thymidine kinase 1 (TK1). Stable TK2-deficient cell lines showed a reduction of TK2 levels close to 80%. In quiescent conditions, TK2-deficient cells showed severe mtDNA depletion, also close to 80% the control levels. However, TK2-deficient clones showed increased cytochrome c oxidase activity, higher cytochrome c oxidase subunit I transcript levels and higher subunit II protein expression respect to control cells. No alterations of the deoxynucleotide pools were found, whereas a reduction in the expression of genes involved in nucleoside/nucleotide homeostasis (human equilibrative nucleoside transporter 1, thymidine phosphorylase) and mtDNA maintenance (DNA-polymerase γ, mitochondrial transcription factor A) was observed. Our findings highlight the importance of cellular compensatory mechanisms that enhance the expression of respiratory components to ensure respiratory activity despite profound depletion in mtDNA levels.

Glutaredoxin-2 controls cardiac mitochondrial dynamics and energetics in mice, and protects against human cardiac pathologies

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Georges N. Kanaan

2018-04-01

Full Text Available Glutaredoxin 2 (GRX2, a mitochondrial glutathione-dependent oxidoreductase, is central to glutathione homeostasis and mitochondrial redox, which is crucial in highly metabolic tissues like the heart. Previous research showed that absence of Grx2, leads to impaired mitochondrial complex I function, hypertension and cardiac hypertrophy in mice but the impact on mitochondrial structure and function in intact cardiomyocytes and in humans has not been explored. We hypothesized that Grx2 controls cardiac mitochondrial dynamics and function in cellular and mouse models, and that low expression is associated with human cardiac dysfunction. Here we show that Grx2 absence impairs mitochondrial fusion, ultrastructure and energetics in primary cardiomyocytes and cardiac tissue. Moreover, provision of the glutathione precursor, N-acetylcysteine (NAC to Grx2-/- mice did not restore glutathione redox or prevent impairments. Using genetic and histopathological data from the human Genotype-Tissue Expression consortium we demonstrate that low GRX2 is associated with fibrosis, hypertrophy, and infarct in the left ventricle. Altogether, GRX2 is important in the control of cardiac mitochondrial structure and function, and protects against human cardiac pathologies. Keywords: Human heart, Mitochondria, Oxidative stress, Redox, Cardiac metabolism, Cardiac hypertrophy

Oxidative stress induced by palytoxin in human keratinocytes is mediated by a H{sup +}-dependent mitochondrial pathway

Energy Technology Data Exchange (ETDEWEB)

Pelin, Marco, E-mail: marco.pelin@phd.units.it [Department of Life Science, University of Trieste, Via L. Giorgieri 7/9, 34127 Trieste (Italy); Ponti, Cristina, E-mail: cponti@units.it [Department of Life Science, University of Trieste, Via L. Giorgieri 7/9, 34127 Trieste (Italy); Sosa, Silvio, E-mail: silvio.sosa@econ.units.it [Department of Life Science, University of Trieste, Via L. Giorgieri 7/9, 34127 Trieste (Italy); Gibellini, Davide, E-mail: davide.gibellini@unibo.it [Department of Haematology and Oncological Sciences, University of Bologna, Via Massarenti 9, 40138 Bologna (Italy); Florio, Chiara, E-mail: florioc@units.it [Department of Life Science, University of Trieste, Via L. Giorgieri 7/9, 34127 Trieste (Italy); Tubaro, Aurelia, E-mail: tubaro@units.it [Department of Life Science, University of Trieste, Via L. Giorgieri 7/9, 34127 Trieste (Italy)

2013-01-01

In the last decades, massive blooms of palytoxin (PLTX)-producing Ostreopsis cf. ovata have been observed along Mediterranean coasts, usually associated to human respiratory and cutaneous problems. At the molecular level, PLTX induces a massive intracellular Na{sup +} influx due to the transformation of Na{sup +}/K{sup +} ATPase in a cationic channel. Recently, we have demonstrated that Na{sup +} overload is the crucial step in mediating overproduction of reactive oxygen species (ROS) and cell death in human HaCaT keratinocytes, tentatively explaining PLTX-induced skin irritant effects. In the present study the molecular mechanisms of ROS production induced by PLTX-mediated Na{sup +} intracellular overload have been investigated. In HaCaT cells, PLTX exposure caused accumulation of superoxide anion, but not of nitric oxide or peroxynitrite/hydroxyl radicals. Even if RT-PCR and western blot analysis revealed an early NOX-2 and iNOS gene and protein over-expressions, their active involvement seemed to be only partial since selective inhibitors did not completely reduce O{sub 2}{sup −} production. A significant role of other enzymes (COX-1, COX-2, XO) was not evidenced. Nigericin, that counteracts Na{sup +}-mediated H{sup +}-imbalance, dissipating ΔpH across mitochondrial inner membrane, and the uncouplers DNP significantly reduced O{sub 2}{sup −} production. These inhibitions were synergistic when co-exposed with complex-I inhibitor rotenone. These results suggest a novel mechanism of O{sub 2}{sup −} production induced by PLTX-mediated ionic imbalance. Indeed, the H{sup +} intracellular overload that follows PLTX-induced intracellular Na{sup +} accumulation, could enhance ΔpH across mitochondrial inner membrane, that seems to be the driving force for O{sub 2}{sup −} production by reversing mitochondrial electron transport. Highlights: ► PLTX induces superoxide (O{sub 2}{sup −}) production by reversing mitochondrial transport chain. ► The mechanism of

The Mitochondrial Protein Atlas: A Database of Experimentally Verified Information on the Human Mitochondrial Proteome.

Science.gov (United States)

Godin, Noa; Eichler, Jerry

2017-09-01

Given its central role in various biological systems, as well as its involvement in numerous pathologies, the mitochondrion is one of the best-studied organelles. However, although the mitochondrial genome has been extensively investigated, protein-level information remains partial, and in many cases, hypothetical. The Mitochondrial Protein Atlas (MPA; URL: lifeserv.bgu.ac.il/wb/jeichler/MPA ) is a database that provides a complete, manually curated inventory of only experimentally validated human mitochondrial proteins. The MPA presently contains 911 unique protein entries, each of which is associated with at least one experimentally validated and referenced mitochondrial localization. The MPA also contains experimentally validated and referenced information defining function, structure, involvement in pathologies, interactions with other MPA proteins, as well as the method(s) of analysis used in each instance. Connections to relevant external data sources are offered for each entry, including links to NCBI Gene, PubMed, and Protein Data Bank. The MPA offers a prototype for other information sources that allow for a distinction between what has been confirmed and what remains to be verified experimentally.

Mitochondrial fission proteins regulate programmed cell death in yeast.

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Fannjiang, Yihru; Cheng, Wen-Chih; Lee, Sarah J; Qi, Bing; Pevsner, Jonathan; McCaffery, J Michael; Hill, R Blake; Basañez, Gorka; Hardwick, J Marie

2004-11-15

The possibility that single-cell organisms undergo programmed cell death has been questioned in part because they lack several key components of the mammalian cell death machinery. However, yeast encode a homolog of human Drp1, a mitochondrial fission protein that was shown previously to promote mammalian cell death and the excessive mitochondrial fragmentation characteristic of apoptotic mammalian cells. In support of a primordial origin of programmed cell death involving mitochondria, we found that the Saccharomyces cerevisiae homolog of human Drp1, Dnm1, promotes mitochondrial fragmentation/degradation and cell death following treatment with several death stimuli. Two Dnm1-interacting factors also regulate yeast cell death. The WD40 repeat protein Mdv1/Net2 promotes cell death, consistent with its role in mitochondrial fission. In contrast to its fission function in healthy cells, Fis1 unexpectedly inhibits Dnm1-mediated mitochondrial fission and cysteine protease-dependent cell death in yeast. Furthermore, the ability of yeast Fis1 to inhibit mitochondrial fission and cell death can be functionally replaced by human Bcl-2 and Bcl-xL. Together, these findings indicate that yeast and mammalian cells have a conserved programmed death pathway regulated by a common molecular component, Drp1/Dnm1, that is inhibited by a Bcl-2-like function.

Major genomic mitochondrial lineages delineate early human expansions

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Flores Carlos

2001-08-01

Full Text Available Abstract Background The phylogeographic distribution of human mitochondrial DNA variations allows a genetic approach to the study of modern Homo sapiens dispersals throughout the world from a female perspective. As a new contribution to this study we have phylogenetically analysed complete mitochondrial DNA(mtDNA sequences from 42 human lineages, representing major clades with known geographic assignation. Results We show the relative relationships among the 42 lineages and present more accurate temporal calibrations than have been previously possible to give new perspectives as how modern humans spread in the Old World. Conclusions The first detectable expansion occurred around 59,000–69,000 years ago from Africa, independently colonizing western Asia and India and, following this southern route, swiftly reaching east Asia. Within Africa, this expansion did not replace but mixed with older lineages detectable today only in Africa. Around 39,000–52,000 years ago, the western Asian branch spread radially, bringing Caucasians to North Africa and Europe, also reaching India, and expanding to north and east Asia. More recent migrations have entangled but not completely erased these primitive footprints of modern human expansions.

What Is Mitochondrial DNA?

Science.gov (United States)

... 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 ...

Mitochondrial transcription factor A protects human retinal ...

African Journals Online (AJOL)

Purpose: To investigate the impact of mitochondrial transcription factor A (TFAM), as a modulator of NF-κB, on proliferation of hypoxia-induced human retinal endothelial cell (HREC), and the probable mechanism. Methods: After exposure to hypoxia (1 % O2) for 5 days, cell proliferation and cell cycle of HREC were ...

Cryopreservation of human skeletal muscle impairs mitochondrial function

DEFF Research Database (Denmark)

Larsen, Steen; Wright-Paradis, C; Gnaiger, E

2012-01-01

functionality after long term cryopreservation (1 year). Skeletal muscle samples were preserved in dimethyl sulfoxide (DMSO) for later analysis. Human skeletal muscle fibres were thawed and permeabilised with saponin, and mitochondrial respiration was measured by high-resolution respirometry. The capacity...

Molecular basis for vulnerability to mitochondrial and oxidative stress in a neuroendocrine CRI-G1 cell line.

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Natasha Chandiramani

2011-01-01

Full Text Available Many age-associated disorders (including diabetes, cancer, and neurodegenerative diseases are linked to mitochondrial dysfunction, which leads to impaired cellular bioenergetics and increased oxidative stress. However, it is not known what genetic and molecular pathways underlie differential vulnerability to mitochondrial dysfunction observed among different cell types.Starting with an insulinoma cell line as a model for a neuronal/endocrine cell type, we isolated a novel subclonal line (named CRI-G1-RS that was more susceptible to cell death induced by mitochondrial respiratory chain inhibitors than the parental CRI-G1 line (renamed CRI-G1-RR for clarity. Compared to parental RR cells, RS cells were also more vulnerable to direct oxidative stress, but equally vulnerable to mitochondrial uncoupling and less vulnerable to protein kinase inhibition-induced apoptosis. Thus, differential vulnerability to mitochondrial toxins between these two cell types likely reflects differences in their ability to handle metabolically generated reactive oxygen species rather than differences in ATP production/utilization or in downstream apoptotic machinery. Genome-wide gene expression analysis and follow-up biochemical studies revealed that, in this experimental system, increased vulnerability to mitochondrial and oxidative stress was associated with (1 inhibition of ARE/Nrf2/Keap1 antioxidant pathway; (2 decreased expression of antioxidant and phase I/II conjugation enzymes, most of which are Nrf2 transcriptional targets; (3 increased expression of molecular chaperones, many of which are also considered Nrf2 transcriptional targets; (4 increased expression of β cell-specific genes and transcription factors that specify/maintain β cell fate; and (5 reconstitution of glucose-stimulated insulin secretion.The molecular profile presented here will enable identification of individual genes or gene clusters that shape vulnerability to mitochondrial dysfunction and

Changes in the human mitochondrial genome after treatment of malignant disease

International Nuclear Information System (INIS)

Wardell, Theresa M.; Ferguson, Elaine; Chinnery, Patrick F.; Borthwick, Gillian M.; Taylor, Robert W.; Jackson, Graham; Craft, Alan; Lightowlers, Robert N.; Howell, Neil; Turnbull, Douglass M.

2003-01-01

Mitochondrial DNA (mtDNA) is the only extrachromosomal DNA in human cells. The mitochondrial genome encodes essential information for the synthesis of the mitochondrial respiratory chain. Inherited defects of this genome are an important cause of human disease. In addition, the mitochondrial genome seems to be particularly prone to DNA damage and acquired mutations may have a role in ageing, cancer and neurodegeneration. We wished to determine if radiotherapy and chemotherapy used in the treatment of cancer could induce changes in the mitochondrial genome. Such changes would be an important genetic marker of DNA damage and may explain some of the adverse effects of treatment. We studied samples from patients who had received radiotherapy and chemotherapy for point mutations within the mtDNA control region, and for large-scale deletions. In blood samples from patients, we found a significantly increased number of point mutations compared to the control subjects. In muscle biopsies from 7 of 8 patients whom had received whole body irradiation as well as chemotherapy, the level of a specific mtDNA deletion was significantly greater than in control subjects. Our studies have shown that in patients who have been treated for cancer there is an increased level of mtDNA damage

Effect of remifentanil on mitochondrial oxygen consumption of cultured human hepatocytes.

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Siamak Djafarzadeh

Full Text Available During sepsis, liver dysfunction is common, and failure of mitochondria to effectively couple oxygen consumption with energy production has been described. In addition to sepsis, pharmacological agents used to treat septic patients may contribute to mitochondrial dysfunction. This study addressed the hypothesis that remifentanil interacts with hepatic mitochondrial oxygen consumption. The human hepatoma cell line HepG2 and their isolated mitochondria were exposed to remifentanil, with or without further exposure to tumor necrosis factor-α (TNF-α. Mitochondrial oxygen consumption was measured by high-resolution respirometry, Caspase-3 protein levels by Western blotting, and cytokine levels by ELISA. Inhibitory κBα (IκBα phosphorylation, measurement of the cellular ATP content and mitochondrial membrane potential in intact cells were analysed using commercial ELISA kits. Maximal cellular respiration increased after one hour of incubation with remifentanil, and phosphorylation of IκBα occurred, denoting stimulation of nuclear factor κB (NF-κB. The effect on cellular respiration was not present at 2, 4, 8 or 16 hours of incubation. Remifentanil increased the isolated mitochondrial respiratory control ratio of complex-I-dependent respiration without interfering with maximal respiration. Preincubation with the opioid receptor antagonist naloxone prevented a remifentanil-induced increase in cellular respiration. Remifentanil at 10× higher concentrations than therapeutic reduced mitochondrial membrane potential and ATP content without uncoupling oxygen consumption and basal respiration levels. TNF-α exposure reduced respiration of complex-I, -II and -IV, an effect which was prevented by prior remifentanil incubation. Furthermore, prior remifentanil incubation prevented TNF-α-induced IL-6 release of HepG2 cells, and attenuated fragmentation of pro-caspase-3 into cleaved active caspase 3 (an early marker of apoptosis. Our data suggest that

Mitochondrial nucleoid interacting proteins support mitochondrial protein synthesis.

Science.gov (United States)

He, J; Cooper, H M; Reyes, A; Di Re, M; Sembongi, H; Litwin, T R; Gao, J; Neuman, K C; Fearnley, I M; Spinazzola, A; Walker, J E; Holt, I J

2012-07-01

Mitochondrial ribosomes and translation factors co-purify with mitochondrial nucleoids of human cells, based on affinity protein purification of tagged mitochondrial DNA binding proteins. Among the most frequently identified proteins were ATAD3 and prohibitin, which have been identified previously as nucleoid components, using a variety of methods. Both proteins are demonstrated to be required for mitochondrial protein synthesis in human cultured cells, and the major binding partner of ATAD3 is the mitochondrial ribosome. Altered ATAD3 expression also perturbs mtDNA maintenance and replication. These findings suggest an intimate association between nucleoids and the machinery of protein synthesis in mitochondria. ATAD3 and prohibitin are tightly associated with the mitochondrial membranes and so we propose that they support nucleic acid complexes at the inner membrane of the mitochondrion.

Plastid and mitochondrial genomes of Coccophora langsdorfii (Fucales, Phaeophyceae and the utility of molecular markers.

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Louis Graf

Full Text Available Coccophora langsdorfii (Turner Greville (Fucales is an intertidal brown alga that is endemic to Northeast Asia and increasingly endangered by habitat loss and climate change. We sequenced the complete circular plastid and mitochondrial genomes of C. langsdorfii. The circular plastid genome is 124,450 bp and contains 139 protein-coding, 28 tRNA and 6 rRNA genes. The circular mitochondrial genome is 35,660 bp and contains 38 protein-coding, 25 tRNA and 3 rRNA genes. The structure and gene content of the C. langsdorfii plastid genome is similar to those of other species in the Fucales. The plastid genomes of brown algae in other orders share similar gene content but exhibit large structural recombination. The large in-frame insert in the cox2 gene in the mitochondrial genome of C. langsdorfii is typical of other brown algae. We explored the effect of this insertion on the structure and function of the cox2 protein. We estimated the usefulness of 135 plastid genes and 35 mitochondrial genes for developing molecular markers. This study shows that 29 organellar genes will prove efficient for resolving brown algal phylogeny. In addition, we propose a new molecular marker suitable for the study of intraspecific genetic diversity that should be tested in a large survey of populations of C. langsdorfii.

Erythropoietin treatment enhances muscle mitochondrial capacity in humans

DEFF Research Database (Denmark)

Plenge, Ulla; Belhage, Bo; Guadalupe-Grau, Amelia

2012-01-01

in humans. In six healthy volunteers rhEpo was administered by sub-cutaneous injection over 8 weeks with oral iron (100 mg) supplementation taken daily. Mitochondrial OXPHOS was quantified by high-resolution respirometry in saponin-permeabilized muscle fibers obtained from biopsies of the vastus lateralis...

Nuclear counterparts of the cytoplasmic mitochondrial 12S rRNA gene: a problem of ancient DNA and molecular phylogenies.

Science.gov (United States)

van der Kuyl, A C; Kuiken, C L; Dekker, J T; Perizonius, W R; Goudsmit, J

1995-06-01

Monkey mummy bones and teeth originating from the North Saqqara Baboon Galleries (Egypt), soft tissue from a mummified baboon in a museum collection, and nineteenth/twentieth-century skin fragments from mangabeys were used for DNA extraction and PCR amplification of part of the mitochondrial 12S rRNA gene. Sequences aligning with the 12S rRNA gene were recovered but were only distantly related to contemporary monkey mitochondrial 12S rRNA sequences. However, many of these sequences were identical or closely related to human nuclear DNA sequences resembling mitochondrial 12S rRNA (isolated from a cell line depleted in mitochondria) and therefore have to be considered contamination. Subsequently in a separate study we were able to recover genuine mitochondrial 12S rRNA sequences from many extant species of nonhuman Old World primates and sequences closely resembling the human nuclear integrations. Analysis of all sequences by the neighbor-joining (NJ) method indicated that mitochondrial DNA sequences and their nuclear counterparts can be divided into two distinct clusters. One cluster contained all temporary cytoplasmic mitochondrial DNA sequences and approximately half of the monkey nuclear mitochondriallike sequences. A second cluster contained most human nuclear sequences and the other half of monkey nuclear sequences with a separate branch leading to human and gorilla mitochondrial and nuclear sequences. Sequences recovered from ancient materials were equally divided between the two clusters. These results constitute a warning for when working with ancient DNA or performing phylogenetic analysis using mitochondrial DNA as a target sequence: Nuclear counterparts of mitochondrial genes may lead to faulty interpretation of results.

DNA repair of UV photoproducts and mutagenesis in human mitochondrial DNA

International Nuclear Information System (INIS)

Pascucci, B.; Dogliotti, E.; Versteegh, A.; Hoffen, A. van; Zeeland, A.A. van; Mullenders, L.H.F.

1997-01-01

The induction and repair of DNA photolesions and mutations in the mitochondrial (mt) DNA of human cells in culture were analysed after cell exposure to UV-C light. The level of induction of cyclobutane pyrimidine dimers (CPD) in mitochondrial and nuclear DNA was comparable, while a higher frequency of pyrimidine (6-4) pyrimidone photoproducts (6-4 PP) was detected in mitochondrial than in nuclear DNA. Besides the known defect in CPD removal, mitochondria were shown to be deficient also in the excision of 6-4 PP. The effects of repair-defective conditions for the two major UV photolesions on mutagensis was assessed by analysing the frequency and spectrum of spontaneous and UV-induced mutations by restriction site mutation (RSM) method in a restriction endonuclease site, NciI (5'CCCGG3') located within the coding sequence of the mitochondrial gene for tRNA Leu . The spontaneous mutation frequency and spectrum at the NciI site of mitochondrial DNA was very similar to the RSM background mutation frequency (approximately 10 -5 ) and type (predominantly GC > AT transitions at GL 1 ) of the NciI site). Conversely, an approximately tenfold increase over background mutation frequency was recorded after cell exposure to 20 J/m 2 . In this case, the majority of mutations were C > T transitions preferentially located on the non-transcribed DNA strand at C 1 and C 2 of the NciI site. This mutation spectrum is expected by UV mutagenesis. This is the first evidence of induction of mutations in mitochondrial DNA by treatment of human cells with a carcinogen. (author)

Human C4orf14 interacts with the mitochondrial nucleoid and is involved in the biogenesis of the small mitochondrial ribosomal subunit.

Science.gov (United States)

He, J; Cooper, H M; Reyes, A; Di Re, M; Kazak, L; Wood, S R; Mao, C C; Fearnley, I M; Walker, J E; Holt, I J

2012-07-01

The bacterial homologue of C4orf14, YqeH, has been linked to assembly of the small ribosomal subunit. Here, recombinant C4orf14 isolated from human cells, co-purified with the small, 28S subunit of the mitochondrial ribosome and the endogenous protein co-fractionated with the 28S subunit in sucrose gradients. Gene silencing of C4orf14 specifically affected components of the small subunit, leading to decreased protein synthesis in the organelle. The GTPase of C4orf14 was critical to its interaction with the 28S subunit, as was GTP. Therefore, we propose that C4orf14, with bound GTP, binds to components of the 28S subunit facilitating its assembly, and GTP hydrolysis acts as the release mechanism. C4orf14 was also found to be associated with human mitochondrial nucleoids, and C4orf14 gene silencing caused mitochondrial DNA depletion. In vitro C4orf14 is capable of binding to DNA. The association of C4orf14 with mitochondrial translation factors and the mitochondrial nucleoid suggests that the 28S subunit is assembled at the mitochondrial nucleoid, enabling the direct transfer of messenger RNA from the nucleoid to the ribosome in the organelle.

Analysis of the mitochondrial maxicircle of Trypanosoma lewisi, a neglected human pathogen

Czech Academy of Sciences Publication Activity Database

Lin, R.-H.; Lai, D.-H.; Zheng, L.-L.; Wu, J.; Lukeš, Julius; Hide, G.; Lun, Z.-R.

2015-01-01

Roč. 8, 30 December 2015 (2015), s. 665 ISSN 1756-3305 Institutional support: RVO:60077344 Keywords : Trypanosoma lewisi * Kinetoplast maxicircle * Mitochondrial DNA * RNA editing * Palindrome Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 3.234, year: 2015

Mitochondrial protein adducts formation and mitochondrial dysfunction during N-acetyl-m-aminophenol (AMAP)-induced hepatotoxicity in primary human hepatocytes

International Nuclear Information System (INIS)

Xie, Yuchao; McGill, Mitchell R.; Du, Kuo; Dorko, Kenneth; Kumer, Sean C.; Schmitt, Timothy M.; Ding, Wen-Xing; Jaeschke, Hartmut

2015-01-01

3′-Hydroxyacetanilide or N-acetyl-meta-aminophenol (AMAP) is generally regarded as a non-hepatotoxic analog of acetaminophen (APAP). Previous studies demonstrated the absence of toxicity after AMAP in mice, hamsters, primary mouse hepatocytes and several cell lines. In contrast, experiments with liver slices suggested that it may be toxic to human hepatocytes; however, the mechanism of toxicity is unclear. To explore this, we treated primary human hepatocytes (PHH) with AMAP or APAP for up to 48 h and measured several parameters to assess metabolism and injury. Although less toxic than APAP, AMAP dose-dependently triggered cell death in PHH as indicated by alanine aminotransferase (ALT) release and propidium iodide (PI) staining. Similar to APAP, AMAP also significantly depleted glutathione (GSH) in PHH and caused mitochondrial damage as indicated by glutamate dehydrogenase (GDH) release and the JC-1 assay. However, unlike APAP, AMAP treatment did not cause relevant c-jun-N-terminal kinase (JNK) activation in the cytosol or phospho-JNK translocation to mitochondria. To compare, AMAP toxicity was assessed in primary mouse hepatocytes (PMH). No cytotoxicity was observed as indicated by the lack of lactate dehydrogenase release and no PI staining. Furthermore, there was no GSH depletion or mitochondrial dysfunction after AMAP treatment in PMH. Immunoblotting for arylated proteins suggested that AMAP treatment caused extensive mitochondrial protein adduct formation in PHH but not in PMH. In conclusion, AMAP is hepatotoxic in PHH and the mechanism involves the formation of mitochondrial protein adducts and mitochondrial dysfunction. - Highlights: • AMAP induces cell death in primary human hepatocytes (PHH). • AMAP does not cause cell death in primary mouse hepatocytes (PMH). • AMAP leads to mitochondria dysfunction in PHH but not PMH. • Protein adduct formation and dysfunction in mitochondria correlate with toxicity.

Mitochondrial protein adducts formation and mitochondrial dysfunction during N-acetyl-m-aminophenol (AMAP)-induced hepatotoxicity in primary human hepatocytes

Energy Technology Data Exchange (ETDEWEB)

Xie, Yuchao; McGill, Mitchell R.; Du, Kuo; Dorko, Kenneth [Department of Pharmacology, Toxicology and Therapeutics, University of Kansas Medical Center, Kansas City, KS 66160 (United States); Kumer, Sean C.; Schmitt, Timothy M. [Department of Surgery, University of Kansas Medical Center, Kansas City, KS 66160 (United States); Ding, Wen-Xing [Department of Pharmacology, Toxicology and Therapeutics, University of Kansas Medical Center, Kansas City, KS 66160 (United States); Jaeschke, Hartmut, E-mail: hjaeschke@kumc.edu [Department of Pharmacology, Toxicology and Therapeutics, University of Kansas Medical Center, Kansas City, KS 66160 (United States)

2015-12-01

3′-Hydroxyacetanilide or N-acetyl-meta-aminophenol (AMAP) is generally regarded as a non-hepatotoxic analog of acetaminophen (APAP). Previous studies demonstrated the absence of toxicity after AMAP in mice, hamsters, primary mouse hepatocytes and several cell lines. In contrast, experiments with liver slices suggested that it may be toxic to human hepatocytes; however, the mechanism of toxicity is unclear. To explore this, we treated primary human hepatocytes (PHH) with AMAP or APAP for up to 48 h and measured several parameters to assess metabolism and injury. Although less toxic than APAP, AMAP dose-dependently triggered cell death in PHH as indicated by alanine aminotransferase (ALT) release and propidium iodide (PI) staining. Similar to APAP, AMAP also significantly depleted glutathione (GSH) in PHH and caused mitochondrial damage as indicated by glutamate dehydrogenase (GDH) release and the JC-1 assay. However, unlike APAP, AMAP treatment did not cause relevant c-jun-N-terminal kinase (JNK) activation in the cytosol or phospho-JNK translocation to mitochondria. To compare, AMAP toxicity was assessed in primary mouse hepatocytes (PMH). No cytotoxicity was observed as indicated by the lack of lactate dehydrogenase release and no PI staining. Furthermore, there was no GSH depletion or mitochondrial dysfunction after AMAP treatment in PMH. Immunoblotting for arylated proteins suggested that AMAP treatment caused extensive mitochondrial protein adduct formation in PHH but not in PMH. In conclusion, AMAP is hepatotoxic in PHH and the mechanism involves the formation of mitochondrial protein adducts and mitochondrial dysfunction. - Highlights: • AMAP induces cell death in primary human hepatocytes (PHH). • AMAP does not cause cell death in primary mouse hepatocytes (PMH). • AMAP leads to mitochondria dysfunction in PHH but not PMH. • Protein adduct formation and dysfunction in mitochondria correlate with toxicity.

Melatonin and human mitochondrial diseases

Directory of Open Access Journals (Sweden)

Reza Sharafati-Chaleshtori

2017-01-01

Full Text Available Mitochondrial dysfunction is one of the main causative factors in a wide variety of complications such as neurodegenerative disorders, ischemia/reperfusion, aging process, and septic shock. Decrease in respiratory complex activity, increase in free radical production, increase in mitochondrial synthase activity, increase in nitric oxide production, and impair in electron transport system and/or mitochondrial permeability are considered as the main factors responsible for mitochondrial dysfunction. Melatonin, the pineal gland hormone, is selectively taken up by mitochondria and acts as a powerful antioxidant, regulating the mitochondrial bioenergetic function. Melatonin increases the permeability of membranes and is the stimulator of antioxidant enzymes including superoxide dismutase, glutathione peroxidase, glutathione reductase, and catalase. It also acts as an inhibitor of lipoxygenase. Melatonin can cause resistance to oxidation damage by fixing the microsomal membranes. Melatonin has been shown to retard aging and inhibit neurodegenerative disorders, ischemia/reperfusion, septic shock, diabetes, cancer, and other complications related to oxidative stress. The purpose of the current study, other than introducing melatonin, was to present the recent findings on clinical effects in diseases related to mitochondrial dysfunction including diabetes, cancer, gastrointestinal diseases, and diseases related to brain function.

Molecular mechanisms of extensive mitochondrial gene rearrangementin plethodontid salamanders

Energy Technology Data Exchange (ETDEWEB)

Mueller, Rachel Lockridge; Boore, Jeffrey L.

2005-06-01

Extensive gene rearrangement is reported in the mitochondrial genomes of lungless salamanders (Plethodontidae). In each genome with a novel gene order, there is evidence that the rearrangement was mediated by duplication of part of the mitochondrial genome, including the presence of both pseudogenes and additional, presumably functional, copies of duplicated genes. All rearrangement-mediating duplications include either the origin of light strand replication and the nearby tRNA genes or the regions flanking the origin of heavy strand replication. The latter regions comprise nad6, trnE, cob, trnT, an intergenic spacer between trnT and trnP and, in some genomes, trnP, the control region, trnF, rrnS, trnV, rrnL, trnL1, and nad1. In some cases, two copies of duplicated genes, presumptive regulatory regions, and/or sequences with no assignable function have been retained in the genome following the initial duplication; in other genomes, only one of the duplicated copies has been retained. Both tandem and non-tandem duplications are present in these genomes, suggesting different duplication mechanisms. In some of these mtDNAs, up to 25 percent of the total length is composed of tandem duplications of non-coding sequence that includes putative regulatory regions and/or pseudogenes of tRNAs and protein-coding genes along with otherwise unassignable sequences. These data indicate that imprecise initiation and termination of replication, slipped-strand mispairing, and intra-molecular recombination may all have played a role in generating repeats during the evolutionary history of plethodontid mitochondrial genomes.

Abnormal mitochondrial respiration in failed human myocardium.

Science.gov (United States)

Sharov, V G; Todor, A V; Silverman, N; Goldstein, S; Sabbah, H N

2000-12-01

Chronic heart failure (HF) is associated with morphologic abnormalities of cardiac mitochondria including hyperplasia, reduced organelle size and compromised structural integrity. In this study, we examined whether functional abnormalities of mitochondrial respiration are also present in myocardium of patients with advanced HF. Mitochondrial respiration was examined using a Clark electrode in an oxygraph cell containing saponin-skinned muscle bundles obtained from myocardium of failed explanted human hearts due to ischemic (ICM, n=9) or idiopathic dilated (IDC, n=9) cardiomyopathy. Myocardial specimens from five normal donor hearts served as controls (CON). Basal respiratory rate, respiratory rate after addition of the substrates glutamate and malate (V(SUB)), state 3 respiration (after addition of ADP, V(ADP)) and respiration after the addition of atractyloside (V(AT)) were measured in scar-free muscle bundles obtained from the subendocardial (ENDO) and subepicardial (EPI) thirds of the left ventricular (LV) free wall, interventricular septum and right ventricular (RV) free wall. There were no differences in basal and substrate-supported respiration between CON and HF regardless of etiology. V(ADP)was significantly depressed both in ICM and IDC compared to CON in all the regions studied. The respiratory control ratio, V(ADP)/V(AT), was also significantly decreased in HF compared to CON. In both ICM and IDC, V(ADP)was significantly lower in ENDO compared to EPI. The results indicate that mitochondrial respiration is abnormal in the failing human heart. The findings support the concept of low myocardial energy production in HF via oxidative phosphorylation, an abnormality with a potentially impact on global cardiac performance. Copyright 2000 Academic Press.

Nicotine induces mitochondrial fission through mitofusin degradation in human multipotent embryonic carcinoma cells

Energy Technology Data Exchange (ETDEWEB)

Hirata, Naoya; Yamada, Shigeru [Division of Pharmacology, National Institute of Health Sciences (Japan); Asanagi, Miki [Division of Pharmacology, National Institute of Health Sciences (Japan); Faculty of Engineering, Department of Materials Science and Engineering, Yokohama National University (Japan); Sekino, Yuko [Division of Pharmacology, National Institute of Health Sciences (Japan); Kanda, Yasunari, E-mail: kanda@nihs.go.jp [Division of Pharmacology, National Institute of Health Sciences (Japan)

2016-02-05

Nicotine is considered to contribute to the health risks associated with cigarette smoking. Nicotine exerts its cellular functions by acting on nicotinic acetylcholine receptors (nAChRs), and adversely affects normal embryonic development. However, nicotine toxicity has not been elucidated in human embryonic stage. In the present study, we examined the cytotoxic effects of nicotine in human multipotent embryonal carcinoma cell line NT2/D1. We found that exposure to 10 μM nicotine decreased intracellular ATP levels and inhibited proliferation of NT2/D1 cells. Because nicotine suppressed energy production, which is a critical mitochondrial function, we further assessed the effects of nicotine on mitochondrial dynamics. Staining with MitoTracker revealed that 10 μM nicotine induced mitochondrial fragmentation. The levels of the mitochondrial fusion proteins, mitofusins 1 and 2, were also reduced in cells exposed to nicotine. These nicotine effects were blocked by treatment with mecamylamine, a nonselective nAChR antagonist. These data suggest that nicotine degrades mitofusin in NT2/D1 cells and thus induces mitochondrial dysfunction and cell growth inhibition in a nAChR-dependent manner. Thus, mitochondrial function in embryonic cells could be used to assess the developmental toxicity of chemicals.

Nicotine induces mitochondrial fission through mitofusin degradation in human multipotent embryonic carcinoma cells

International Nuclear Information System (INIS)

Hirata, Naoya; Yamada, Shigeru; Asanagi, Miki; Sekino, Yuko; Kanda, Yasunari

2016-01-01

Nicotine is considered to contribute to the health risks associated with cigarette smoking. Nicotine exerts its cellular functions by acting on nicotinic acetylcholine receptors (nAChRs), and adversely affects normal embryonic development. However, nicotine toxicity has not been elucidated in human embryonic stage. In the present study, we examined the cytotoxic effects of nicotine in human multipotent embryonal carcinoma cell line NT2/D1. We found that exposure to 10 μM nicotine decreased intracellular ATP levels and inhibited proliferation of NT2/D1 cells. Because nicotine suppressed energy production, which is a critical mitochondrial function, we further assessed the effects of nicotine on mitochondrial dynamics. Staining with MitoTracker revealed that 10 μM nicotine induced mitochondrial fragmentation. The levels of the mitochondrial fusion proteins, mitofusins 1 and 2, were also reduced in cells exposed to nicotine. These nicotine effects were blocked by treatment with mecamylamine, a nonselective nAChR antagonist. These data suggest that nicotine degrades mitofusin in NT2/D1 cells and thus induces mitochondrial dysfunction and cell growth inhibition in a nAChR-dependent manner. Thus, mitochondrial function in embryonic cells could be used to assess the developmental toxicity of chemicals.

Mitochondrial regulation of epigenetics and its role in human diseases

DEFF Research Database (Denmark)

Minocherhomji, Sheroy; Tollefsbol, Trygve O; Singh, Keshav K

2012-01-01

as the sole pathogenic factor suggesting that additional mechanisms contribute to lack of genotype and clinical phenotype correlationship. An increasing number of studies have identified a possible effect on the epigenetic landscape of the nuclear genome as a consequence of mitochondrial dysfunction....... In particular, these studies demonstrate reversible or irreversible changes in genomic DNA methylation profiles of the nuclear genome. Here we review how mitochondria damage checkpoint (mitocheckpoint) induces epigenetic changes in the nucleus. Persistent pathogenic mutations in mtDNA may also lead...... to epigenetic changes causing genomic instability in the nuclear genome. We propose that "mitocheckpoint" mediated epigenetic and genetic changes may play key roles in phenotypic variation related to mitochondrial diseases or host of human diseases in which mitochondrial defect plays a primary role....

Activation-dependent mitochondrial translocation of Foxp3 in human hepatocytes

International Nuclear Information System (INIS)

Rojas, Joselyn; Teran-Angel, Guillermo; Barbosa, Luisa; Peterson, Darrell L.; Berrueta, Lisbeth; Salmen, Siham

2016-01-01

Foxp3 is considered to be the master regulator for the development and function of regulatory T cells (Treg). Recently Foxp3, has been detected in extra lymphoid tissue, and in hepatocytes and has been associated with hepatocellular carcinoma (HCC), although its role has not been defined. Since it is expected that there is a relationship between protein localization, activity and cellular function, the aim of this study was to explore the subcellular localization of Foxp3 in resting and stimulated human hepatocytes. Foxp3 expression was measured by flow cytometry, subcellular fractioning, and immunofluorescence, and this data was used to track the shuttling of Foxp3 in different subcellular compartments in hepatocytes (HepG2 cell line), stimulated by using the PKC activators (PMA), core and preS1/2 antigen from hepatitis B virus (HBV). Our data shows that besides the nuclear location, mitochondrial translocation was detected after stimulation with PMA and at to a lesser extent, with preS1/2. In addition, Foxp3 is localizes at outer mitochondrial membrane. These results suggest a non-canonical role of Foxp3 in the mitochondrial compartment in human hepatocytes, and opens a new field about their role in liver damages during HBV infection. - Highlights: • The expression and subcellular distribution of Foxp3, is modulated by PMA and preS1/2. • PMA and preS1/2 increase Foxp3 expression on HepG2. • PMA and preS1/2 induce foxp3 enrichment at mitochondrial, microsomal and nuclear compartments. • Results suggest a non-canonical function of Foxp3 or a mitochondrial transcriptional activity.

Activation-dependent mitochondrial translocation of Foxp3 in human hepatocytes

Energy Technology Data Exchange (ETDEWEB)

Rojas, Joselyn; Teran-Angel, Guillermo; Barbosa, Luisa [Instituto de Inmunología Clínica, Facultad de Medicina, Universidad de Los Andes, Merida (Venezuela, Bolivarian Republic of); Peterson, Darrell L. [Department of Biochemistry and Molecular Biology, Virginia Commonwealth University, Richmond, VA (United States); Berrueta, Lisbeth, E-mail: lberruet@ula.ve [Instituto de Inmunología Clínica, Facultad de Medicina, Universidad de Los Andes, Merida (Venezuela, Bolivarian Republic of); Division of Preventive Medicine, Brigham and Women' s Hospital, Harvard Medical School, Boston, MA (United States); Salmen, Siham, E-mail: sihamsa@ula.ve [Instituto de Inmunología Clínica, Facultad de Medicina, Universidad de Los Andes, Merida (Venezuela, Bolivarian Republic of)

2016-05-01

Foxp3 is considered to be the master regulator for the development and function of regulatory T cells (Treg). Recently Foxp3, has been detected in extra lymphoid tissue, and in hepatocytes and has been associated with hepatocellular carcinoma (HCC), although its role has not been defined. Since it is expected that there is a relationship between protein localization, activity and cellular function, the aim of this study was to explore the subcellular localization of Foxp3 in resting and stimulated human hepatocytes. Foxp3 expression was measured by flow cytometry, subcellular fractioning, and immunofluorescence, and this data was used to track the shuttling of Foxp3 in different subcellular compartments in hepatocytes (HepG2 cell line), stimulated by using the PKC activators (PMA), core and preS1/2 antigen from hepatitis B virus (HBV). Our data shows that besides the nuclear location, mitochondrial translocation was detected after stimulation with PMA and at to a lesser extent, with preS1/2. In addition, Foxp3 is localizes at outer mitochondrial membrane. These results suggest a non-canonical role of Foxp3 in the mitochondrial compartment in human hepatocytes, and opens a new field about their role in liver damages during HBV infection. - Highlights: • The expression and subcellular distribution of Foxp3, is modulated by PMA and preS1/2. • PMA and preS1/2 increase Foxp3 expression on HepG2. • PMA and preS1/2 induce foxp3 enrichment at mitochondrial, microsomal and nuclear compartments. • Results suggest a non-canonical function of Foxp3 or a mitochondrial transcriptional activity.

Mitochondrial DNA Hypomethylation Is a Biomarker Associated with Induced Senescence in Human Fetal Heart Mesenchymal Stem Cells

Directory of Open Access Journals (Sweden)

Dehai Yu

2017-01-01

Full Text Available Background. Fetal heart can regenerate to restore its normal anatomy and function in response to injury, but this regenerative capacity is lost within the first week of postnatal life. Although the specific molecular mechanisms remain to be defined, it is presumed that aging of cardiac stem or progenitor cells may contribute to the loss of regenerative potential. Methods. To study this aging-related dysfunction, we cultured mesenchymal stem cells (MSCs from human fetal heart tissues. Senescence was induced by exposing cells to chronic oxidative stress/low serum. Mitochondrial DNA methylation was examined during the period of senescence. Results. Senescent MSCs exhibited flattened and enlarged morphology and were positive for the senescence-associated beta-galactosidase (SA-β-Gal. By scanning the entire mitochondrial genome, we found that four CpG islands were hypomethylated in close association with senescence in MSCs. The mitochondrial COX1 gene, which encodes the main subunit of the cytochrome c oxidase complex and contains the differentially methylated CpG island 4, was upregulated in MSCs in parallel with the onset of senescence. Knockdown of DNA methyltransferases (DNMT1, DNMT3a, and DNMT3B also upregulated COX1 expression and induced cellular senescence in MSCs. Conclusions. This study demonstrates that mitochondrial CpG hypomethylation may serve as a critical biomarker associated with cellular senescence induced by chronic oxidative stress.

Insulin increases phosphorylation of mitochondrial proteins in human skeletal muscle in vivo

DEFF Research Database (Denmark)

Zhao, Xiaolu; Bak, Steffen; Pedersen, Andreas James Thestrup

2014-01-01

, we investigated the effect of insulin on the phosphorylation of mitochondrial proteins in human skeletal muscle in vivo. Using a combination of TiO2 phosphopeptide-enrichment, HILIC fractionation, and LC−MS/MS, we compared the phosphoproteomes of isolated mitochondria from skeletal muscle samples...... obtained from healthy individuals before and after 4 h of insulin infusion. In total, we identified 207 phosphorylation sites in 95 mitochondrial proteins. Of these phosphorylation sites, 45% were identified in both basal and insulin-stimulated samples. Insulin caused a 2-fold increase in the number...... of different mitochondrial phosphopeptides (87 ± 7 vs 40 ± 7, p = 0.015) and phosphoproteins (46 ± 2 vs 26 ± 3, p = 0.005) identified in each mitochondrial preparation. Almost half of the mitochondrial phosphorylation sites (n = 94) were exclusively identified in the insulin-stimulated state and included...

Stimulated human mast cells secrete mitochondrial components that have autocrine and paracrine inflammatory actions.

Directory of Open Access Journals (Sweden)

Bodi Zhang

Full Text Available Mast cells are hematopoietically-derived tissue immune cells that participate in acquired and innate immunity, as well as in inflammation through release of many chemokines and cytokines, especially in response to the pro-inflammatory peptide substance P (SP. Inflammation is critical in the pathogenesis of many diseases, but the trigger(s is often unknown. We investigated if mast cell stimulation leads to secretion of mitochondrial components and whether these could elicit autocrine and/or paracrine inflammatory effects. Here we show that human LAD2 mast cells stimulated by IgE/anti-IgE or by the SP led to secretion of mitochondrial particles, mitochondrial (mt mtDNA and ATP without cell death. Mitochondria purified from LAD2 cells and, when mitochondria added to mast cells trigger degranulation and release of histamine, PGD(2, IL-8, TNF, and IL-1β. This stimulatory effect is partially inhibited by an ATP receptor antagonist and by DNAse. These results suggest that the mitochondrial protein fraction may also contribute. Purified mitochondria also stimulate IL-8 and vascular endothelial growth factor (VEGF release from cultured human keratinocytes, and VEGF release from primary human microvascular endothelial cells. In order to investigate if mitochondrial components could be secreted in vivo, we injected rats intraperiotoneally (ip with compound 48/80, which mimicks the action of SP. Peritoneal mast cells degranulated and mitochondrial particles were documented by transimission electron microscopy outside the cells. We also wished to investigate if mitochondrial components secreted locally could reach the systemic circulation. Administration ip of mtDNA isolated from LAD2 cells in rats was detected in their serum within 4 hr, indicating that extravascular mtDNA could enter the systemic circulation. Secretion of mitochondrial components from stimulated live mast cells may act as "autopathogens" contributing to the pathogenesis of inflammatory

Molecular identification of Malaysian Chrysomya megacephala (Fabricius) and Chrysomya rufifacies (Macquart) using life stage specific mitochondrial DNA.

Science.gov (United States)

Kavitha, R; Tan, T C; Lee, H L; Nazni, W A; Sofian, A M

2013-06-01

DNA identification of blow fly species can be a very useful tool in forensic entomology. One of the potential benefits that mitochondrial DNA (mtDNA) has offered in the field of forensic entomology is species determination. Conventional identification methods have limitations for sibling and closely related species of blow fly and stage and quality of the specimen used. This could be overcome by DNA-based identification methods using mitochondrial DNA which does not demand intact or undamaged specimens. Mitochondrial DNA is usually isolated from whole blow fly and legs. Alternate sources for mitochondrial DNA isolation namely, egg, larva, puparium and empty puparium were explored in this study. The sequence of DNA obtained for each sample for every life cycle stage was 100% identical for a particular species, indicating that the egg, 1st instar, 2nd instar, 3rd instar, pupa, empty puparium and adult from the same species and obtained from same generation will exhibit similar DNA sequences. The present study also highlighted the usefulness of collecting all life cycle stages of blow fly during crime scene investigation with proper preservation and subsequent molecular analysis. Molecular identification provides a strong basis for species identification and will prove an invaluable contribution to forensic entomology as an investigative tool in Malaysia.

Development of GMP-1 a molecular chaperone network modulator protecting mitochondrial function and its assessment in fly and mice models of Alzheimer's disease.

Science.gov (United States)

Pavlov, Pavel F; Hutter-Paier, Birgit; Havas, Daniel; Windisch, Manfred; Winblad, Bengt

2018-04-27

Mitochondrial dysfunction is an early feature of Alzheimer's disease (AD) and may play an important role in the pathogenesis of disease. It has been shown that amyloid beta peptide (Aβ) and amyloid precursor protein (APP) interact with mitochondria contributing to the mitochondrial dysfunction in AD. Prevention of abnormal protein targeting to mitochondria can protect normal mitochondrial function, increase neuronal survival and at the end, ameliorate symptoms of AD and other neurodegenerative disorders. First steps of mitochondrial protein import are coordinated by molecular chaperones Hsp70 and Hsp90 that bind to the newly synthesized mitochondria-destined proteins and deliver them to the protein import receptors on the surface of organelle. Here, we have described the development of a novel compound named GMP-1 that disrupts interactions between Hsp70/Hsp90 molecular chaperones and protein import receptor Tom70. GMP-1 treatment of SH-SY5Y cells results in decrease in mitochondria-associated APP and protects SH-SY5Y cells from toxic effect of Aβ 1-42 exposure. Experiments in drosophila and mice models of AD demonstrated neuroprotective effect of GMP-1 treatment, improvement in memory and behaviour tests as well as restoration of mitochondrial function. © 2018 The Authors. Journal of Cellular and Molecular Medicine published by John Wiley & Sons Ltd and Foundation for Cellular and Molecular Medicine.

Transcutaneous application of carbon dioxide (CO2 induces mitochondrial apoptosis in human malignant fibrous histiocytoma in vivo.

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Yasuo Onishi

Full Text Available Mitochondria play an essential role in cellular energy metabolism and apoptosis. Previous studies have demonstrated that decreased mitochondrial biogenesis is associated with cancer progression. In mitochondrial biogenesis, peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α regulates the activities of multiple nuclear receptors and transcription factors involved in mitochondrial proliferation. Previously, we showed that overexpression of PGC-1α leads to mitochondrial proliferation and induces apoptosis in human malignant fibrous histiocytoma (MFH cells in vitro. We also demonstrated that transcutaneous application of carbon dioxide (CO(2 to rat skeletal muscle induces PGC-1α expression and causes an increase in mitochondrial proliferation. In this study, we utilized a murine model of human MFH to determine the effect of transcutaneous CO(2 exposure on PGC-1α expression, mitochondrial proliferation and cellular apoptosis. PGC-1α expression was evaluated by quantitative real-time PCR, while mitochondrial proliferation was assessed by immunofluorescence staining and the relative copy number of mitochondrial DNA (mtDNA was assessed by real-time PCR. Immunofluorescence staining and DNA fragmentation assays were used to examine mitochondrial apoptosis. We also evaluated the expression of mitochondrial apoptosis related proteins, such as caspases, cytochorome c and Bax, by immunoblot analysis. We show that transcutaneous application of CO(2 induces PGC-1α expression, and increases mitochondrial proliferation and apoptosis of tumor cells, significantly reducing tumor volume. Proteins involved in the mitochondrial apoptotic cascade, including caspase 3 and caspase 9, were elevated in CO(2 treated tumors compared to control. We also observed an enrichment of cytochrome c in the cytoplasmic fraction and Bax protein in the mitochondrial fraction of CO(2 treated tumors, highlighting the involvement of mitochondria in apoptosis

Human 2'-phosphodiesterase localizes to the mitochondrial matrix with a putative function in mitochondrial RNA turnover

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Poulsen, Jesper Buchhave; Andersen, Kasper Røjkjær; Kjær, Karina Hansen

2011-01-01

. Interestingly, 2′-PDE shares both functionally and structurally characteristics with the CCR4-type exonuclease–endonuclease–phosphatase family of deadenylases. Here we show that 2′-PDE locates to the mitochondrial matrix of human cells, and comprise an active 3′–5′ exoribonuclease exhibiting a preference...

MICU1 Serves as a Molecular Gatekeeper to Prevent In Vivo Mitochondrial Calcium Overload

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Julia C. Liu

2016-08-01

Full Text Available MICU1 is a component of the mitochondrial calcium uniporter, a multiprotein complex that also includes MICU2, MCU, and EMRE. Here, we describe a mouse model of MICU1 deficiency. MICU1−/− mitochondria demonstrate altered calcium uptake, and deletion of MICU1 results in significant, but not complete, perinatal mortality. Similar to afflicted patients, viable MICU1−/− mice manifest marked ataxia and muscle weakness. Early in life, these animals display a range of biochemical abnormalities, including increased resting mitochondrial calcium levels, altered mitochondrial morphology, and reduced ATP. Older MICU1−/− mice show marked, spontaneous improvement coincident with improved mitochondrial calcium handling and an age-dependent reduction in EMRE expression. Remarkably, deleting one allele of EMRE helps normalize calcium uptake while simultaneously rescuing the high perinatal mortality observed in young MICU1−/− mice. Together, these results demonstrate that MICU1 serves as a molecular gatekeeper preventing calcium overload and suggests that modulating the calcium uniporter could have widespread therapeutic benefits.

Molecular diversification of Trichuris spp. from Sigmodontinae (Cricetidae) rodents from Argentina based on mitochondrial DNA sequences.

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Callejón, Rocío; Robles, María Del Rosario; Panei, Carlos Javier; Cutillas, Cristina

2016-08-01

A molecular phylogenetic hypothesis is presented for the genus Trichuris based on sequence data from mitochondrial cytochrome c oxidase 1 (cox1) and cytochrome b (cob). The taxa consisted of nine populations of whipworm from five species of Sigmodontinae rodents from Argentina. Bayesian Inference, Maximum Parsimony, and Maximum Likelihood methods were used to infer phylogenies for each gene separately but also for the combined mitochondrial data and the combined mitochondrial and nuclear dataset. Phylogenetic results based on cox1 and cob mitochondrial DNA (mtDNA) revealed three clades strongly resolved corresponding to three different species (Trichuris navonae, Trichuris bainae, and Trichuris pardinasi) showing phylogeographic variation, but relationships among Trichuris species were poorly resolved. Phylogenetic reconstruction based on concatenated sequences had greater phylogenetic resolution for delimiting species and populations intra-specific of Trichuris than those based on partitioned genes. Thus, populations of T. bainae and T. pardinasi could be affected by geographical factors and co-divergence parasite-host.

A Lentinus edodes polysaccharide induces mitochondrial-mediated apoptosis in human cervical carcinoma HeLa cells.

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Ya, Guowei

2017-10-01

In this study, a homogeneous polysaccharide (LEP1) with an average molecular weight of 53kDa was successfully purified from the fruiting bodies of Lentinus edodes and its anticancer efficacy on human cervical carcinoma HeLa cells in vitro and associated possible molecular mechanism were also evaluated. MTT assay showed that LEP1 exhibited a dose-dependent inhibitory effect on the proliferation of HeLa cells and caused apoptotic death. Our present findings provided the first evidence that LEP1 induced the apoptosis of HeLa cells via a mitochondria dependent pathway, as indicated by an increase in Bax/Bcl-2 ratio, a loss of mitochondrial membrane potential (Δym), the release of cytochrome c from the mitochondria to the cytosol, activation of caspase-9 and caspase-3, and cleavage of poly (ADP-ribose) polymerase (PARP) in HeLa cells. These combined results unequivocally indicated that the involvement of mitochondria-mediated signaling pathway in LEP1-induced apoptosis and strongly provided experimental evidence for the use of LEP1 as a potential therapeutic agent in the prevention and treatment of human cervical carcinoma. Copyright © 2017 Elsevier B.V. All rights reserved.

Mitochondrial Molecular Pathophysiology of Nonalcoholic Fatty Liver Disease: A Proteomics Approach

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Natalia Nuño-Lámbarri

2016-03-01

Full Text Available Nonalcoholic fatty liver disease (NAFLD is a chronic liver condition that can progress to nonalcoholic steatohepatitis, cirrhosis and cancer. It is considered an emerging health problem due to malnourishment or a high-fat diet (HFD intake, which is observed worldwide. It is well known that the hepatocytes’ apoptosis phenomenon is one of the most important features of NAFLD. Thus, this review focuses on revealing, through a proteomics approach, the complex network of protein interactions that promote fibrosis, liver cell stress, and apoptosis. According to different types of in vitro and murine models, it has been found that oxidative/nitrative protein stress leads to mitochondrial dysfunction, which plays a major role in stimulating NAFLD damage. Human studies have revealed the importance of novel biomarkers, such as retinol-binding protein 4, lumican, transgelin 2 and hemoglobin, which have a significant role in the disease. The post-genome era has brought proteomics technology, which allows the determination of molecular pathogenesis in NAFLD. This has led to the search for biomarkers which improve early diagnosis and optimal treatment and which may effectively prevent fatal consequences such as cirrhosis or cancer.

Oxidative stress and mitochondrial impairment can be separated from lipofuscin accumulation in aged human skeletal muscle

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Hütter, Eveline; Skovbro, Mette; Lener, Barbara

2007-01-01

According to the free radical theory of aging, reactive oxygen species (ROS) act as a driving force of the aging process, and it is generally believed that mitochondrial dysfunction is a major source of increased oxidative stress in tissues with high content of mitochondria, such as muscle or brain....... However, recent experiments in mouse models of premature aging have questioned the role of mitochondrial ROS production in premature aging. To address the role of mitochondrial impairment and ROS production for aging in human muscles, we have analyzed mitochondrial properties in muscle fibres isolated...... from the vastus lateralis of young and elderly donors. Mitochondrial respiratory functions were addressed by high-resolution respirometry, and ROS production was analyzed by in situ staining with the redox-sensitive dye dihydroethidium. We found that aged human skeletal muscles contain fully functional...

Advances in the quantification of mitochondrial function in primary human immune cells through extracellular flux analysis.

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Dequina Nicholas

Full Text Available Numerous studies show that mitochondrial energy generation determines the effectiveness of immune responses. Furthermore, changes in mitochondrial function may regulate lymphocyte function in inflammatory diseases like type 2 diabetes. Analysis of lymphocyte mitochondrial function has been facilitated by introduction of 96-well format extracellular flux (XF96 analyzers, but the technology remains imperfect for analysis of human lymphocytes. Limitations in XF technology include the lack of practical protocols for analysis of archived human cells, and inadequate data analysis tools that require manual quality checks. Current analysis tools for XF outcomes are also unable to automatically assess data quality and delete untenable data from the relatively high number of biological replicates needed to power complex human cell studies. The objectives of work presented herein are to test the impact of common cellular manipulations on XF outcomes, and to develop and validate a new automated tool that objectively analyzes a virtually unlimited number of samples to quantitate mitochondrial function in immune cells. We present significant improvements on previous XF analyses of primary human cells that will be absolutely essential to test the prediction that changes in immune cell mitochondrial function and fuel sources support immune dysfunction in chronic inflammatory diseases like type 2 diabetes.

Mitochondrial Dynamics: Coupling Mitochondrial Fitness with Healthy Aging.

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Sebastián, David; Palacín, Manuel; Zorzano, Antonio

2017-03-01

Aging is associated with a decline in mitochondrial function and the accumulation of abnormal mitochondria. However, the precise mechanisms by which aging promotes these mitochondrial alterations and the role of the latter in aging are still not fully understood. Mitochondrial dynamics is a key process regulating mitochondrial function and quality. Altered expression of some mitochondrial dynamics proteins has been recently associated with aging and with age-related alterations in yeast, Caenorhabditis elegans, mice, and humans. Here, we review the link between alterations in mitochondrial dynamics, aging, and age-related impairment. We propose that the dysregulation of mitochondrial dynamics leads to age-induced accumulation of unhealthy mitochondria and contributes to alterations linked to aging, such as diabetes and neurodegeneration. Copyright © 2017 Elsevier Ltd. All rights reserved.

2-ethylpyridine, a cigarette smoke component, causes mitochondrial damage in human retinal pigment epithelial cells in vitro

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S Mansoor

2014-01-01

Full Text Available Purpose: Our goal was to identify the cellular and molecular effects of 2-ethylpyridine (2-EP, a component of cigarette smoke on human retinal pigment epithelial cells (ARPE-19 in vitro. Materials and Methods: ARPE-19 cells were exposed to varying concentrations of 2-EP. Cell viability (CV was measured by a trypan blue dye exclusion assay. Caspase-3/7 and caspase-9 activities were measured by fluorochrome assays. The production of reactive oxygen/nitrogen species (ROS/RNS was detected with a 2′,7′-dichlorodihydrofluorescein diacetate dye assay. The JC-1 assay was used to measure mitochondrial membrane potential (ΔΨm. Mitochondrial redox potential was measured using a RedoxSensor Red kit and mitochondria were evaluated with Mitotracker dye. Results: After 2-EP exposure, ARPE-19 cells showed significantly decreased CV, increased caspase-3/7 and caspase-9 activities, elevated ROS/RNS levels, decreased ΔΨm value and decreased redox fluorescence when compared with control samples. Conclusions: These results show that 2-EP treatment induced cell death by caspase-dependent apoptosis associated with an oxidative stress and mitochondrial dysfunction. These data represent a possible mechanism by which smoking contributes to age-related macular degeneration and other retinal diseases and identify mitochondria as a target for future therapeutic interventions.

Abolition of peroxiredoxin-5 mitochondrial targeting during canid evolution.

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Valérie Van der Eecken

Full Text Available In human, the subcellular targeting of peroxiredoxin-5 (PRDX5, a thioredoxin peroxidase, is dependent on the use of multiple alternative transcription start sites and two alternative in-frame translation initiation sites, which determine whether or not the region encoding a mitochondrial targeting sequence (MTS is translated. In the present study, the abolition of PRDX5 mitochondrial targeting in dog is highlighted and the molecular mechanism underlying the loss of mitochondrial PRDX5 during evolution is examined. Here, we show that the absence of mitochondrial PRDX5 is generalized among the extant canids and that the first events leading to PRDX5 MTS abolition in canids involve a mutation in the more 5' translation initiation codon as well as the appearance of a STOP codon. Furthermore, we found that PRDX5 MTS functionality is maintained in giant panda and northern elephant seal, which are phylogenetically closely related to canids. Also, the functional consequences of the restoration of mitochondrial PRDX5 in dog Madin-Darby canine kidney (MDCK cells were investigated. The restoration of PRDX5 mitochondrial targeting in MDCK cells, instead of protecting, provokes deleterious effects following peroxide exposure independently of its peroxidase activity, indicating that mitochondrial PRDX5 gains cytotoxic properties under acute oxidative stress in MDCK cells. Altogether our results show that, although mitochondrial PRDX5 cytoprotective function against oxidative stress has been clearly demonstrated in human and rodents, PRDX5 targeting to mitochondria has been evolutionary lost in canids. Moreover, restoration of mitochondrial PRDX5 in dog MDCK cells, instead of conferring protection against peroxide exposure, makes them more vulnerable.

Bacteria, Yeast, Worms, and Flies: Exploiting Simple Model Organisms to Investigate Human Mitochondrial Diseases

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Rea, Shane L.; Graham, Brett H.; Nakamaru-Ogiso, Eiko; Kar, Adwitiya; Falk, Marni J.

2010-01-01

The extensive conservation of mitochondrial structure, composition, and function across evolution offers a unique opportunity to expand our understanding of human mitochondrial biology and disease. By investigating the biology of much simpler model organisms, it is often possible to answer questions that are unreachable at the clinical level.…

A mitochondrial cytochrome b mutation causing severe respiratory chain enzyme deficiency in humans and yeast.

NARCIS (Netherlands)

Blakely, E.L.; Mitchell, A.L.; Fisher, N.; Meunier, B.; Nijtmans, L.G.J.; Schaefer, A.M.; Jackson, M.J.; Turnbull, D.M.; Taylor, R.W.

2005-01-01

Whereas the majority of disease-related mitochondrial DNA mutations exhibit significant biochemical and clinical heterogeneity, mutations within the mitochondrially encoded human cytochrome b gene (MTCYB) are almost exclusively associated with isolated complex III deficiency in muscle and a clinical

The mitochondrial elongation factors MIEF1 and MIEF2 exert partially distinct functions in mitochondrial dynamics

Energy Technology Data Exchange (ETDEWEB)

Liu, Tong; Yu, Rong [Department of Oncology–Pathology, Karolinska Institutet, CCK R8:05, Karolinska University Hospital Solna, SE-171 76 Stockholm (Sweden); Jin, Shao-Bo [Department of Cell and Molecular Biology, Karolinska Institutet, SE-171 77 Stockholm (Sweden); Han, Liwei [Department of Oncology–Pathology, Karolinska Institutet, CCK R8:05, Karolinska University Hospital Solna, SE-171 76 Stockholm (Sweden); Lendahl, Urban [Department of Cell and Molecular Biology, Karolinska Institutet, SE-171 77 Stockholm (Sweden); Zhao, Jian, E-mail: Jian.Zhao@ki.se [Department of Oncology–Pathology, Karolinska Institutet, CCK R8:05, Karolinska University Hospital Solna, SE-171 76 Stockholm (Sweden); Nistér, Monica [Department of Oncology–Pathology, Karolinska Institutet, CCK R8:05, Karolinska University Hospital Solna, SE-171 76 Stockholm (Sweden)

2013-11-01

Mitochondria are dynamic organelles whose morphology is regulated by a complex balance of fission and fusion processes, and we still know relatively little about how mitochondrial dynamics is regulated. MIEF1 (also called MiD51) has recently been characterized as a key regulator of mitochondrial dynamics and in this report we explore the functions of its paralog MIEF2 (also called MiD49), to learn to what extent MIEF2 is functionally distinct from MIEF1. We show that MIEF1 and MIEF2 have many functions in common. Both are anchored in the mitochondrial outer membrane, recruit Drp1 from the cytoplasm to the mitochondrial surface and cause mitochondrial fusion, and MIEF2, like MIEF1, can interact with Drp1 and hFis1. MIEF1 and MIEF2, however, also differ in certain aspects. MIEF1 and MIEF2 are differentially expressed in human tissues during development. When overexpressed, MIEF2 exerts a stronger fusion-promoting effect than MIEF1, and in line with this, hFis1 and Mff can only partially revert the MIEF2-induced fusion phenotype, whereas MIEF1-induced fusion is reverted to a larger extent by hFis1 and Mff. MIEF2 forms high molecular weight oligomers, while MIEF1 is largely present as a dimer. Furthermore, MIEF1 and MIEF2 use distinct domains for oligomerization: in MIEF1, the region from amino acid residues 109–154 is required, whereas oligomerization of MIEF2 depends on amino acid residues 1 to 49, i.e. the N-terminal end. We also show that oligomerization of MIEF1 is not required for its mitochondrial localization and interaction with Drp1. In conclusion, our data suggest that the mitochondrial regulators MIEF1 and MIEF2 exert partially distinct functions in mitochondrial dynamics. - Highlights: • MIEF1 and MIEF2 recruit Drp1 to mitochondria and cause mitochondrial fusion. • MIEF2, like MIEF1, can interact with Drp1 and hFis1. • MIEF1 and MIEF2 are differentially expressed in human tissues during development. • MIEF2 exerts a stronger fusion

The mitochondrial elongation factors MIEF1 and MIEF2 exert partially distinct functions in mitochondrial dynamics

International Nuclear Information System (INIS)

Liu, Tong; Yu, Rong; Jin, Shao-Bo; Han, Liwei; Lendahl, Urban; Zhao, Jian; Nistér, Monica

2013-01-01

Mitochondria are dynamic organelles whose morphology is regulated by a complex balance of fission and fusion processes, and we still know relatively little about how mitochondrial dynamics is regulated. MIEF1 (also called MiD51) has recently been characterized as a key regulator of mitochondrial dynamics and in this report we explore the functions of its paralog MIEF2 (also called MiD49), to learn to what extent MIEF2 is functionally distinct from MIEF1. We show that MIEF1 and MIEF2 have many functions in common. Both are anchored in the mitochondrial outer membrane, recruit Drp1 from the cytoplasm to the mitochondrial surface and cause mitochondrial fusion, and MIEF2, like MIEF1, can interact with Drp1 and hFis1. MIEF1 and MIEF2, however, also differ in certain aspects. MIEF1 and MIEF2 are differentially expressed in human tissues during development. When overexpressed, MIEF2 exerts a stronger fusion-promoting effect than MIEF1, and in line with this, hFis1 and Mff can only partially revert the MIEF2-induced fusion phenotype, whereas MIEF1-induced fusion is reverted to a larger extent by hFis1 and Mff. MIEF2 forms high molecular weight oligomers, while MIEF1 is largely present as a dimer. Furthermore, MIEF1 and MIEF2 use distinct domains for oligomerization: in MIEF1, the region from amino acid residues 109–154 is required, whereas oligomerization of MIEF2 depends on amino acid residues 1 to 49, i.e. the N-terminal end. We also show that oligomerization of MIEF1 is not required for its mitochondrial localization and interaction with Drp1. In conclusion, our data suggest that the mitochondrial regulators MIEF1 and MIEF2 exert partially distinct functions in mitochondrial dynamics. - Highlights: • MIEF1 and MIEF2 recruit Drp1 to mitochondria and cause mitochondrial fusion. • MIEF2, like MIEF1, can interact with Drp1 and hFis1. • MIEF1 and MIEF2 are differentially expressed in human tissues during development. • MIEF2 exerts a stronger fusion

Targeting mitochondrial phenotypes for non-communicable diseases

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Zhengtang Qi

2016-06-01

Full Text Available The concept that “Exercise is Medicine” has been challenged by the rising prevalence of non-communicable chronic diseases (NCDs. This is partly due to the fact that the underlying mechanisms of how exercise influences energy homeostasis and counteracts high-fat diets and physical inactivity is complex and remains relatively poorly understood on a molecular level. In addition to genetic polymorphisms in humans that lead to gross variations in responsiveness to exercise, adaptation in mitochondrial networks is central to physical activity, inactivity, and diet. To harness the benefits of exercise for NCDs, much work still needs to be done to improve health effectively on a societal level such as developing personalized exercise interventions aided by advances in high-throughput genomics, proteomics, and metabolomics. We propose that understanding the mitochondrial phenotype according to the molecular information of genotypes, lifestyles, and exercise responsiveness in individuals will optimize exercise effects for prevention of NCDs.

Mitochondrial respiration in human viable platelets-Methodology and influence of gender, age and storage

DEFF Research Database (Denmark)

Sjövall, Fredrik; Ehinger, Johannes K H; Marelsson, Sigurður E

2013-01-01

Studying whole cell preparations with intact mitochondria and respiratory complexes has a clear benefit compared to isolated or disrupted mitochondria due to the dynamic interplay between mitochondria and other cellular compartments. Platelet mitochondria have a potential to serve as a source...... of human viable mitochondria when studying mitochondrial physiology and pathogenic mechanisms, as well as for the diagnostics of mitochondrial diseases. The objective of the present study was to perform a detailed evaluation of platelet mitochondrial respiration using high-resolution respirometry. Further...

Insulin resistance and the mitochondrial link. Lessons from cultured human myotubes

DEFF Research Database (Denmark)

Gaster, Michael

2007-01-01

In order to better understand the impact of reduced mitochondrial function for the development of insulin resistance and cellular metabolism, human myotubes were established from lean, obese, and T2D subjects and exposed to mitochondrial inhibitors, either affecting the electron transport chain...... lipid uptake. The metabolic phenotype during respiratory uncoupling resembled the above picture, except for an increase in glucose and palmitate oxidation. Antimycin A and oligomycin treatment induced insulin resistance at the level of glucose and palmitate uptake in all three study groups while......, at the level of glycogen synthesis, insulin resistance was only seen in lean myotubes. Primary insulin resistance in diabetic myotubes was significantly worsened at the level of glucose and lipid uptake. The present study is the first convincing data linking functional mitochondrial impairment per se...

Molecular phylogeny of Toxoplasmatinae: comparison between inferences based on mitochondrial and apicoplast genetic sequences

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Michelle Klein Sercundes

2016-03-01

Full Text Available Abstract Phylogenies within Toxoplasmatinae have been widely investigated with different molecular markers. Here, we studied molecular phylogenies of the Toxoplasmatinae subfamily based on apicoplast and mitochondrial genes. Partial sequences of apicoplast genes coding for caseinolytic protease (clpC and beta subunit of RNA polymerase (rpoB, and mitochondrial gene coding for cytochrome B (cytB were analyzed. Laboratory-adapted strains of the closely related parasites Sarcocystis falcatula and Sarcocystis neurona were investigated, along with Neospora caninum, Neospora hughesi, Toxoplasma gondii (strains RH, CTG and PTG, Besnoitia akodoni, Hammondia hammondiand two genetically divergent lineages of Hammondia heydorni. The molecular analysis based on organellar genes did not clearly differentiate between N. caninum and N. hughesi, but the two lineages of H. heydorni were confirmed. Slight differences between the strains of S. falcatula and S. neurona were encountered in all markers. In conclusion, congruent phylogenies were inferred from the three different genes and they might be used for screening undescribed sarcocystid parasites in order to ascertain their phylogenetic relationships with organisms of the family Sarcocystidae. The evolutionary studies based on organelar genes confirm that the genusHammondia is paraphyletic. The primers used for amplification of clpC and rpoB were able to amplify genetic sequences of organisms of the genus Sarcocystisand organisms of the subfamily Toxoplasmatinae as well.

Hepatocellular toxicity of benzbromarone: Effects on mitochondrial function and structure

International Nuclear Information System (INIS)

Felser, Andrea; Lindinger, Peter W.; Schnell, Dominik; Kratschmar, Denise V.; Odermatt, Alex; Mies, Suzette; Jenö, Paul; Krähenbühl, Stephan

2014-01-01

Highlights: • Benzbromarone impairs the electron transport chain and uncouples mitochondria. • Benzbromarone impairs mitochondrial β-oxidation by inhibiting fatty acid activation. • Benzbromarone disrupts the mitochondrial network and induces apoptosis. - Abstract: Benzbromarone is an uricosuric structurally related to amiodarone and a known mitochondrial toxicant. The aim of the current study was to improve our understanding in the molecular mechanisms of benzbromarone-associated hepatic mitochondrial toxicity. In HepG2 cells and primary human hepatocytes, ATP levels started to decrease in the presence of 25–50 μM benzbromarone for 24–48 h, whereas cytotoxicity was observed only at 100 μM. In HepG2 cells, benzbromarone decreased the mitochondrial membrane potential starting at 50 μM following incubation for 24 h. Additionally, in HepG2 cells, 50 μM benzbromarone for 24 h induced mitochondrial uncoupling,and decreased mitochondrial ATP turnover and maximal respiration. This was accompanied by an increased lactate concentration in the cell culture supernatant, reflecting increased glycolysis as a compensatory mechanism to maintain cellular ATP. Investigation of the electron transport chain revealed a decreased activity of all relevant enzyme complexes. Furthermore, treatment with benzbromarone was associated with increased cellular ROS production, which could be located specifically to mitochondria. In HepG2 cells and in isolated mouse liver mitochondria, benzbromarone also reduced palmitic acid metabolism due to an inhibition of the long-chain acyl CoA synthetase. In HepG2 cells, benzbromarone disrupted the mitochondrial network, leading to mitochondrial fragmentation and a decreased mitochondrial volume per cell. Cell death occurred by both apoptosis and necrosis. The study demonstrates that benzbromarone not only affects the function of mitochondria in HepG2 cells and human hepatocytes, but is also associated with profound changes in mitochondrial

Structure of the Human Mitochondrial Ribosome Studied In Situ by Cryoelectron Tomography.

Science.gov (United States)

Englmeier, Robert; Pfeffer, Stefan; Förster, Friedrich

2017-10-03

Mitochondria maintain their own genome and its corresponding protein synthesis machine, the mitochondrial ribosome (mitoribosome). Mitoribosomes primarily synthesize highly hydrophobic proteins of the inner mitochondrial membrane. Recent studies revealed the complete structure of the isolated mammalian mitoribosome, but its mode of membrane association remained hypothetical. In this study, we used cryoelectron tomography to visualize human mitoribosomes in isolated mitochondria. The subtomogram average of the membrane-associated human mitoribosome reveals a single major contact site with the inner membrane, mediated by the mitochondria-specific protein mL45. A second rRNA-mediated contact site that is present in yeast is absent in humans, resulting in a more variable association of the human mitoribosome with the inner membrane. Despite extensive structural differences of mammalian and fungal mitoribosomal structure, the principal organization of peptide exit tunnel and the mL45 homolog remains invariant, presumably to align the mitoribosome with the membrane-embedded insertion machinery. Copyright © 2017 Elsevier Ltd. All rights reserved.

Definition of the mitochondrial proteome by measurement of molecular masses of membrane proteins

Science.gov (United States)

Carroll, Joe; Fearnley, Ian M.; Walker, John E.

2006-01-01

The covalent structure of a protein is incompletely defined by its gene sequence, and mass spectrometric analysis of the intact protein is needed to detect the presence of any posttranslational modifications. Because most membrane proteins are purified in detergents that are incompatible with mass spectrometric ionization techniques, this essential measurement has not been made on many hydrophobic proteins, and so proteomic data are incomplete. We have extracted membrane proteins from bovine mitochondria and detergent-purified NADH:ubiquinone oxidoreductase (complex I) with organic solvents, fractionated the mixtures by hydrophilic interaction chromatography, and measured the molecular masses of the intact membrane proteins, including those of six subunits of complex I that are encoded in mitochondrial DNA. These measurements resolve long-standing uncertainties about the interpretation of the mitochondrial genome, and they contribute significantly to the definition of the covalent composition of complex I. PMID:17060615

Calorie restriction increases muscle mitochondrial biogenesis in healthy humans.

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Anthony E Civitarese

2007-03-01

Full Text Available Caloric restriction without malnutrition extends life span in a range of organisms including insects and mammals and lowers free radical production by the mitochondria. However, the mechanism responsible for this adaptation are poorly understood.The current study was undertaken to examine muscle mitochondrial bioenergetics in response to caloric restriction alone or in combination with exercise in 36 young (36.8 +/- 1.0 y, overweight (body mass index, 27.8 +/- 0.7 kg/m(2 individuals randomized into one of three groups for a 6-mo intervention: Control, 100% of energy requirements; CR, 25% caloric restriction; and CREX, caloric restriction with exercise (CREX, 12.5% CR + 12.5% increased energy expenditure (EE. In the controls, 24-h EE was unchanged, but in CR and CREX it was significantly reduced from baseline even after adjustment for the loss of metabolic mass (CR, -135 +/- 42 kcal/d, p = 0.002 and CREX, -117 +/- 52 kcal/d, p = 0.008. Participants in the CR and CREX groups had increased expression of genes encoding proteins involved in mitochondrial function such as PPARGC1A, TFAM, eNOS, SIRT1, and PARL (all, p < 0.05. In parallel, mitochondrial DNA content increased by 35% +/- 5% in the CR group (p = 0.005 and 21% +/- 4% in the CREX group (p < 0.004, with no change in the control group (2% +/- 2%. However, the activity of key mitochondrial enzymes of the TCA (tricarboxylic acid cycle (citrate synthase, beta-oxidation (beta-hydroxyacyl-CoA dehydrogenase, and electron transport chain (cytochrome C oxidase II was unchanged. DNA damage was reduced from baseline in the CR (-0.56 +/- 0.11 arbitrary units, p = 0.003 and CREX (-0.45 +/- 0.12 arbitrary units, p = 0.011, but not in the controls. In primary cultures of human myotubes, a nitric oxide donor (mimicking eNOS signaling induced mitochondrial biogenesis but failed to induce SIRT1 protein expression, suggesting that additional factors may regulate SIRT1 content during CR.The observed increase in

Comparative study of human mitochondrial proteome reveals extensive protein subcellular relocalization after gene duplications

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Huang Yong

2009-11-01

Full Text Available Abstract Background Gene and genome duplication is the principle creative force in evolution. Recently, protein subcellular relocalization, or neolocalization was proposed as one of the mechanisms responsible for the retention of duplicated genes. This hypothesis received support from the analysis of yeast genomes, but has not been tested thoroughly on animal genomes. In order to evaluate the importance of subcellular relocalizations for retention of duplicated genes in animal genomes, we systematically analyzed nuclear encoded mitochondrial proteins in the human genome by reconstructing phylogenies of mitochondrial multigene families. Results The 456 human mitochondrial proteins selected for this study were clustered into 305 gene families including 92 multigene families. Among the multigene families, 59 (64% consisted of both mitochondrial and cytosolic (non-mitochondrial proteins (mt-cy families while the remaining 33 (36% were composed of mitochondrial proteins (mt-mt families. Phylogenetic analyses of mt-cy families revealed three different scenarios of their neolocalization following gene duplication: 1 relocalization from mitochondria to cytosol, 2 from cytosol to mitochondria and 3 multiple subcellular relocalizations. The neolocalizations were most commonly enabled by the gain or loss of N-terminal mitochondrial targeting signals. The majority of detected subcellular relocalization events occurred early in animal evolution, preceding the evolution of tetrapods. Mt-mt protein families showed a somewhat different pattern, where gene duplication occurred more evenly in time. However, for both types of protein families, most duplication events appear to roughly coincide with two rounds of genome duplications early in vertebrate evolution. Finally, we evaluated the effects of inaccurate and incomplete annotation of mitochondrial proteins and found that our conclusion of the importance of subcellular relocalization after gene duplication on

Models of plasma membrane organization can be applied to mitochondrial membranes to target human health and disease with polyunsaturated fatty acids.

Science.gov (United States)

Raza Shaikh, Saame; Brown, David A

2013-01-01

Bioactive n-3 polyunsaturated fatty acids (PUFA), abundant in fish oil, have potential for treating symptoms associated with inflammatory and metabolic disorders; therefore, it is essential to determine their fundamental molecular mechanisms. Recently, several labs have demonstrated the n-3 PUFA docosahexaenoic acid (DHA) exerts anti-inflammatory effects by targeting the molecular organization of plasma membrane microdomains. Here we briefly review the evidence that DHA reorganizes the spatial distribution of microdomains in several model systems. We then emphasize how models on DHA and plasma membrane microdomains can be applied to mitochondrial membranes. We discuss the role of DHA acyl chains in regulating mitochondrial lipid-protein clustering, and how these changes alter several aspects of mitochondrial function. In particular, we summarize effects of DHA on mitochondrial respiration, electron leak, permeability transition, and mitochondrial calcium handling. Finally, we conclude by postulating future experiments that will augment our understanding of DHA-dependent membrane organization in health and disease. Copyright © 2012 Elsevier Ltd. All rights reserved.

A revised timescale for human evolution based on ancient mitochondrial genomes

Czech Academy of Sciences Publication Activity Database

Fu, Q.; Mittnik, A.; Johnson, P. L. F.; Bos, K.; Lari, M.; Bollongino, R.; Sun, Ch.; Giemsch, L.; Schmitz, R.; Burger, J.; Ronchitelli, A. M.; Martini, F.; Cremonesi, R. G.; Svoboda, Jiří; Bauer, P.; Caramelli, D.; Castellano, S.; Reich, D.; Pääbo, S.; Krause, J.

2013-01-01

Roč. 23, April 8 (2013), s. 553-559 ISSN 0960-9822 Institutional support: RVO:68081758 Keywords : mitochondrial genome * human evolution * calibration Subject RIV: AC - Archeology, Anthropology, Ethnology OBOR OECD: Archaeology Impact factor: 9.916, year: 2013

Laminarin Induces Apoptosis of Human Colon Cancer LOVO Cells through a Mitochondrial Pathway

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He Zhang

2012-08-01

Full Text Available Many scientific studies have shown that laminarin has anti-tumor effects, but the anti-tumor mechanism was unclear. The purpose of this study was to investigate the effect of laminarin on the induction of apoptosis in human colon cancer LOVO cells and the molecular mechanism involved. LOVO cells were treated with different concentrations of laminarin at different times. Morphology observations were performed to determine the effects of laminarin on apoptosis of LOVO cells. Flow cytometry (FCM was used to detect the level of intracellular reactive oxygen species (ROS and pH. Laser scanning confocal microscope (LSCM was used to analyze intracellular calcium ion concentration, mitochondrion permeability transition pore (MPTP and mitochondrial membrane potential (MMP. Western blotd were performed to analyze the expressions of Cyt-C, Caspase-9 and -3. The results showed the apoptosis morphology, which showed cell protuberance, concentrated cytoplasm and apoptotic bodies, was obvious after 72 h treatment. Laminarin treatment for 24 h increased the intracellular level of ROS and Ca²⁺; decreased pH value; activated intracellular MPTP and decreased MMP in dose-dependent manners. It also induced the release of Cyt-C and the activation of Caspase-9 and -3. In conclusion, laminarin induces LOVO cell apoptosis through a mitochondrial pathway, suggesting that it could be a potent agent for cancer prevention and treatment.

Genome digging: insight into the mitochondrial genome of Homo.

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Igor V Ovchinnikov

2010-12-01

Full Text Available A fraction of the Neanderthal mitochondrial genome sequence has a similarity with a 5,839-bp nuclear DNA sequence of mitochondrial origin (numt on the human chromosome 1. This fact has never been interpreted. Although this phenomenon may be attributed to contamination and mosaic assembly of Neanderthal mtDNA from short sequencing reads, we explain the mysterious similarity by integration of this numt (mtAncestor-1 into the nuclear genome of the common ancestor of Neanderthals and modern humans not long before their reproductive split.Exploiting bioinformatics, we uncovered an additional numt (mtAncestor-2 with a high similarity to the Neanderthal mtDNA and indicated that both numts represent almost identical replicas of the mtDNA sequences ancestral to the mitochondrial genomes of Neanderthals and modern humans. In the proteins, encoded by mtDNA, the majority of amino acids distinguishing chimpanzees from humans and Neanderthals were acquired by the ancestral hominins. The overall rate of nonsynonymous evolution in Neanderthal mitochondrial protein-coding genes is not higher than in other lineages. The model incorporating the ancestral hominin mtDNA sequences estimates the average divergence age of the mtDNAs of Neanderthals and modern humans to be 450,000-485,000 years. The mtAncestor-1 and mtAncestor-2 sequences were incorporated into the nuclear genome approximately 620,000 years and 2,885,000 years ago, respectively.This study provides the first insight into the evolution of the mitochondrial DNA in hominins ancestral to Neanderthals and humans. We hypothesize that mtAncestor-1 and mtAncestor-2 are likely to be molecular fossils of the mtDNAs of Homo heidelbergensis and a stem Homo lineage. The d(N/d(S dynamics suggests that the effective population size of extinct hominins was low. However, the hominin lineage ancestral to humans, Neanderthals and H. heidelbergensis, had a larger effective population size and possessed genetic diversity

PINK1 is necessary for long term survival and mitochondrial function in human dopaminergic neurons.

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Alison Wood-Kaczmar

2008-06-01

Full Text Available Parkinson's disease (PD is a common age-related neurodegenerative disease and it is critical to develop models which recapitulate the pathogenic process including the effect of the ageing process. Although the pathogenesis of sporadic PD is unknown, the identification of the mendelian genetic factor PINK1 has provided new mechanistic insights. In order to investigate the role of PINK1 in Parkinson's disease, we studied PINK1 loss of function in human and primary mouse neurons. Using RNAi, we created stable PINK1 knockdown in human dopaminergic neurons differentiated from foetal ventral mesencephalon stem cells, as well as in an immortalised human neuroblastoma cell line. We sought to validate our findings in primary neurons derived from a transgenic PINK1 knockout mouse. For the first time we demonstrate an age dependent neurodegenerative phenotype in human and mouse neurons. PINK1 deficiency leads to reduced long-term viability in human neurons, which die via the mitochondrial apoptosis pathway. Human neurons lacking PINK1 demonstrate features of marked oxidative stress with widespread mitochondrial dysfunction and abnormal mitochondrial morphology. We report that PINK1 plays a neuroprotective role in the mitochondria of mammalian neurons, especially against stress such as staurosporine. In addition we provide evidence that cellular compensatory mechanisms such as mitochondrial biogenesis and upregulation of lysosomal degradation pathways occur in PINK1 deficiency. The phenotypic effects of PINK1 loss-of-function described here in mammalian neurons provides mechanistic insight into the age-related degeneration of nigral dopaminergic neurons seen in PD.

Abnormal mitochondrial transport and morphology as early pathological changes in human models of spinal muscular atrophy

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Chong-Chong Xu

2016-01-01

Full Text Available Spinal muscular atrophy (SMA, characterized by specific degeneration of spinal motor neurons, is caused by mutations in the survival of motor neuron 1, telomeric (SMN1 gene and subsequent decreased levels of functional SMN. How the deficiency of SMN, a ubiquitously expressed protein, leads to spinal motor neuron-specific degeneration in individuals affected by SMA remains unknown. In this study, we examined the role of SMN in mitochondrial axonal transport and morphology in human motor neurons by generating SMA type 1 patient-specific induced pluripotent stem cells (iPSCs and differentiating these cells into spinal motor neurons. The initial specification of spinal motor neurons was not affected, but these SMA spinal motor neurons specifically degenerated following long-term culture. Moreover, at an early stage in SMA spinal motor neurons, but not in SMA forebrain neurons, the number of mitochondria, mitochondrial area and mitochondrial transport were significantly reduced in axons. Knocking down of SMN expression led to similar mitochondrial defects in spinal motor neurons derived from human embryonic stem cells, confirming that SMN deficiency results in impaired mitochondrial dynamics. Finally, the application of N-acetylcysteine (NAC mitigated the impairment in mitochondrial transport and morphology and rescued motor neuron degeneration in SMA long-term cultures. Furthermore, NAC ameliorated the reduction in mitochondrial membrane potential in SMA spinal motor neurons, suggesting that NAC might rescue apoptosis and motor neuron degeneration by improving mitochondrial health. Overall, our data demonstrate that SMN deficiency results in abnormal mitochondrial transport and morphology and a subsequent reduction in mitochondrial health, which are implicated in the specific degeneration of spinal motor neurons in SMA.

Molecular phylogeny of the Oriental butterfly genus Arhopala (Lycaenidae, Theclinae) inferred from mitochondrial and nuclear genes

NARCIS (Netherlands)

Megens, H.J.W.C.; Nes, Van W.J.; Moorsel, van C.H.M.; Pierce, N.E.; Jong, de R.

2004-01-01

We present a phylogeny for a selection of species of the butterfly genus Arhopala Boisduval, 1832 based on molecular characters. We sequenced 1778 bases of the mitochondrial genes Cytochrome Oxidase 1 and 2 including tRNALeu, and a 393-bp fragment of the nuclear wingless gene for a total of 42

The mitochondrial genome, a growing interest inside an organelle

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Marco Crimi

2008-03-01

Full Text Available Marco Crimi1, Roberta Rigolio21National Institute of Molecular Genetics (INGM, Functional Genomics Unit, Milan, Italy; 2Department of Neurosciences and Biomedical Technologies, University of Milan Bicocca, Monza, ItalyAbstract: Mitochondria are semi-autonomously reproductive organelles within eukaryotic cells carrying their own genetic material, called the mitochondrial genome (mtDNA. Until some years ago, mtDNA had primarily been used as a tool in population genetics. As scientists began associating mtDNA mutations with dozens of mysterious disorders, as well as the aging process and a variety of chronic degenerative diseases, it became increasingly evident that the information contained in this genome had substantial potential applications to improve human health. Today, mitochondria research covers a wide range of disciplines, including clinical medicine, biochemistry, genetics, molecular cell biology, bioinformatics, plant sciences and physiology. The present review intends to present a summary of the most exiting fields of the mitochondrial research bringing together several contributes in terms of original prospective and future applications.Keywords: mtDNA, heteroplasmy, molecular diagnostics, mitochondriopathies, nanogenomics

Successful enrichment and recovery of whole mitochondrial genomes from ancient human dental calculus.

Science.gov (United States)

Ozga, Andrew T; Nieves-Colón, Maria A; Honap, Tanvi P; Sankaranarayanan, Krithivasan; Hofman, Courtney A; Milner, George R; Lewis, Cecil M; Stone, Anne C; Warinner, Christina

2016-06-01

Archaeological dental calculus is a rich source of host-associated biomolecules. Importantly, however, dental calculus is more accurately described as a calcified microbial biofilm than a host tissue. As such, concerns regarding destructive analysis of human remains may not apply as strongly to dental calculus, opening the possibility of obtaining human health and ancestry information from dental calculus in cases where destructive analysis of conventional skeletal remains is not permitted. Here we investigate the preservation of human mitochondrial DNA (mtDNA) in archaeological dental calculus and its potential for full mitochondrial genome (mitogenome) reconstruction in maternal lineage ancestry analysis. Extracted DNA from six individuals at the 700-year-old Norris Farms #36 cemetery in Illinois was enriched for mtDNA using in-solution capture techniques, followed by Illumina high-throughput sequencing. Full mitogenomes (7-34×) were successfully reconstructed from dental calculus for all six individuals, including three individuals who had previously tested negative for DNA preservation in bone using conventional PCR techniques. Mitochondrial haplogroup assignments were consistent with previously published findings, and additional comparative analysis of paired dental calculus and dentine from two individuals yielded equivalent haplotype results. All dental calculus samples exhibited damage patterns consistent with ancient DNA, and mitochondrial sequences were estimated to be 92-100% endogenous. DNA polymerase choice was found to impact error rates in downstream sequence analysis, but these effects can be mitigated by greater sequencing depth. Dental calculus is a viable alternative source of human DNA that can be used to reconstruct full mitogenomes from archaeological remains. Am J Phys Anthropol 160:220-228, 2016. © 2016 The Authors American Journal of Physical Anthropology Published by Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

The HO-1/CO system regulates mitochondrial-capillary density relationships in human skeletal muscle.

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Pecorella, Shelly R H; Potter, Jennifer V F; Cherry, Anne D; Peacher, Dionne F; Welty-Wolf, Karen E; Moon, Richard E; Piantadosi, Claude A; Suliman, Hagir B

2015-10-15

The heme oxygenase-1 (HO-1)/carbon monoxide (CO) system induces mitochondrial biogenesis, but its biological impact in human skeletal muscle is uncertain. The enzyme system generates CO, which stimulates mitochondrial proliferation in normal muscle. Here we examined whether CO breathing can be used to produce a coordinated metabolic and vascular response in human skeletal muscle. In 19 healthy subjects, we performed vastus lateralis muscle biopsies and tested one-legged maximal O2 uptake (V̇o2max) before and after breathing air or CO (200 ppm) for 1 h daily for 5 days. In response to CO, there was robust HO-1 induction along with increased mRNA levels for nuclear-encoded mitochondrial transcription factor A (Tfam), cytochrome c, cytochrome oxidase subunit IV (COX IV), and mitochondrial-encoded COX I and NADH dehydrogenase subunit 1 (NDI). CO breathing did not increase V̇o2max (1.96 ± 0.51 pre-CO, 1.87 ± 0.50 post-CO l/min; P = not significant) but did increase muscle citrate synthase, mitochondrial density (139.0 ± 34.9 pre-CO, 219.0 ± 36.2 post-CO; no. of mitochondrial profiles/field), myoglobin content and glucose transporter (GLUT4) protein level and led to GLUT4 localization to the myocyte membrane, all consistent with expansion of the tissue O2 transport system. These responses were attended by increased cluster of differentiation 31 (CD31)-positive muscle capillaries (1.78 ± 0.16 pre-CO, 2.37 ± 0.59 post-CO; capillaries/muscle fiber), implying the enrichment of microvascular O2 reserve. The findings support that induction of the HO-1/CO system by CO not only improves muscle mitochondrial density, but regulates myoglobin content, GLUT4 localization, and capillarity in accordance with current concepts of skeletal muscle plasticity. Copyright © 2015 the American Physiological Society.

Construction and confirmation of the plasmid of human mitochondrial DNA 4977 bp deletion induced by ionizing radiation

International Nuclear Information System (INIS)

Chen Xiaosui; Zhou Lijun; Wang Yuxiao; Qu Jia; Feng Jiangbing; Lu Xue; Chen Deqing; Liu Qingjie

2006-01-01

Objective: To construct a stable plasmid that spanning deleted human mitochondrial DNA (mtDNA) 4977 bp induced by ionizing radiation and another one for control DNA fragment, in order to use in the human mitochondrial genome study in the future. Methods: The peripheral blood, which had no mtDNA 4977 bp deletion found in previous study, was exposed to 10 Gy 60 Co γ-rays in vitro. The total cell DNA was extracted and PCR was carried out: a nest-PCR of three-round PCR was used for the mtDNA 4977 bp deletion and one- round regular PCR was used for the control ND1 gene. The PCR products were used for transfection by electroporation and the positive clones were obtained after screening. The plasmid DNA was isolated and sequenced after enzymatic digestion and purification. The sequence result was BLASTed with the human mitochondrial genome. Results: The sizes of PCR products for the flanked 4977 bp deletion and the ND1 gene were similar with those predicted according to GeneBank. The sequences for the positive clones were above 99 per cent homologous with the human mitochondrial genome after BLASTed. Conclusion: The plasmids for deleted human mtDNA 4977 bp and control DNA fragment have been constructed successfully, and they could be used in the quality and quantity studies on human mtDNA 4977 bp deletion. (authors)

Mitochondrial DNA inheritance in the human fungal pathogen Cryptococcus gattii.

Science.gov (United States)

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. Copyright © 2015 Elsevier Inc. All rights reserved.

Disturbed mitochondrial function restricts glutamate uptake in the human Müller glia cell line, MIO-M1

DEFF Research Database (Denmark)

Vohra, Rupali; Gurubaran, Iswariyaraja Sridevi; Henriksen, Ulrik

2017-01-01

Using the human Müller cell line, MIO-M1, the aim was to study the impact of mitochondrial inhibition in Müller glia through antimycin A treatment. MIO-M1 cell survival, levels of released lactate, mitochondrial function, and glutamate uptake were studied in response to mitochondrial inhibition...... and glucose restriction. Lactate release decreased in response to glucose restriction. Combined glucose restriction and blocked mitochondrial activity decreased survival and caused collapse of the respiratory chain measured by oxygen consumption rate and extracellular acidification rate. Mitochondrial...... inhibition caused impaired glutamate uptake and decreased mRNA expression of the glutamate transporter, EAAT1. Over all, we show important roles of mitochondrial activity in MIO-M1 cell function and survival....

Modulation of mitochondrial function and morphology by interaction of Omi/HtrA2 with the mitochondrial fusion factor OPA1

Energy Technology Data Exchange (ETDEWEB)

Kieper, Nicole; Holmstroem, Kira M.; Ciceri, Dalila; Fiesel, Fabienne C. [Center of Neurology and Hertie Institute for Clinical Brain Research, 72076 Tuebingen (Germany); Wolburg, Hartwig [Institute of Pathology, University of Tuebingen, 72076 Tuebingen (Germany); Ziviani, Elena; Whitworth, Alexander J. [Medical Research Council Centre for Developmental and Biomedical Genetics, University of Sheffield, Sheffield S10 2TN (United Kingdom); Martins, L. Miguel [Cell Death Regulation Laboratory, MRC Toxicology Unit, Leicester LE1 9HN (United Kingdom); Kahle, Philipp J., E-mail: philipp.kahle@uni-tuebingen.de [Center of Neurology and Hertie Institute for Clinical Brain Research, 72076 Tuebingen (Germany); Krueger, Rejko, E-mail: rejko.krueger@uni-tuebingen.de [Center of Neurology and Hertie Institute for Clinical Brain Research, 72076 Tuebingen (Germany)

2010-04-15

Loss of Omi/HtrA2 function leads to nerve cell loss in mouse models and has been linked to neurodegeneration in Parkinson's and Huntington's disease. Omi/HtrA2 is a serine protease released as a pro-apoptotic factor from the mitochondrial intermembrane space into the cytosol. Under physiological conditions, Omi/HtrA2 is thought to be involved in protection against cellular stress, but the cytological and molecular mechanisms are not clear. Omi/HtrA2 deficiency caused an accumulation of reactive oxygen species and reduced mitochondrial membrane potential. In Omi/HtrA2 knockout mouse embryonic fibroblasts, as well as in Omi/HtrA2 silenced human HeLa cells and Drosophila S2R+ cells, we found elongated mitochondria by live cell imaging. Electron microscopy confirmed the mitochondrial morphology alterations and showed abnormal cristae structure. Examining the levels of proteins involved in mitochondrial fusion, we found a selective up-regulation of more soluble OPA1 protein. Complementation of knockout cells with wild-type Omi/HtrA2 but not with the protease mutant [S306A]Omi/HtrA2 reversed the mitochondrial elongation phenotype and OPA1 alterations. Finally, co-immunoprecipitation showed direct interaction of Omi/HtrA2 with endogenous OPA1. Thus, we show for the first time a direct effect of loss of Omi/HtrA2 on mitochondrial morphology and demonstrate a novel role of this mitochondrial serine protease in the modulation of OPA1. Our results underscore a critical role of impaired mitochondrial dynamics in neurodegenerative disorders.

Modulation of mitochondrial function and morphology by interaction of Omi/HtrA2 with the mitochondrial fusion factor OPA1

International Nuclear Information System (INIS)

Kieper, Nicole; Holmstroem, Kira M.; Ciceri, Dalila; Fiesel, Fabienne C.; Wolburg, Hartwig; Ziviani, Elena; Whitworth, Alexander J.; Martins, L. Miguel; Kahle, Philipp J.; Krueger, Rejko

2010-01-01

Loss of Omi/HtrA2 function leads to nerve cell loss in mouse models and has been linked to neurodegeneration in Parkinson's and Huntington's disease. Omi/HtrA2 is a serine protease released as a pro-apoptotic factor from the mitochondrial intermembrane space into the cytosol. Under physiological conditions, Omi/HtrA2 is thought to be involved in protection against cellular stress, but the cytological and molecular mechanisms are not clear. Omi/HtrA2 deficiency caused an accumulation of reactive oxygen species and reduced mitochondrial membrane potential. In Omi/HtrA2 knockout mouse embryonic fibroblasts, as well as in Omi/HtrA2 silenced human HeLa cells and Drosophila S2R+ cells, we found elongated mitochondria by live cell imaging. Electron microscopy confirmed the mitochondrial morphology alterations and showed abnormal cristae structure. Examining the levels of proteins involved in mitochondrial fusion, we found a selective up-regulation of more soluble OPA1 protein. Complementation of knockout cells with wild-type Omi/HtrA2 but not with the protease mutant [S306A]Omi/HtrA2 reversed the mitochondrial elongation phenotype and OPA1 alterations. Finally, co-immunoprecipitation showed direct interaction of Omi/HtrA2 with endogenous OPA1. Thus, we show for the first time a direct effect of loss of Omi/HtrA2 on mitochondrial morphology and demonstrate a novel role of this mitochondrial serine protease in the modulation of OPA1. Our results underscore a critical role of impaired mitochondrial dynamics in neurodegenerative disorders.

Reversible infantile mitochondrial diseases.

Science.gov (United States)

Boczonadi, Veronika; Bansagi, Boglarka; Horvath, Rita

2015-05-01

Mitochondrial diseases are usually severe and progressive conditions; however, there are rare forms that show remarkable spontaneous recoveries. Two homoplasmic mitochondrial tRNA mutations (m.14674T>C/G in mt-tRNA(Glu)) have been reported to cause severe infantile mitochondrial myopathy in the first months of life. If these patients survive the first year of life by extensive life-sustaining measures they usually recover and develop normally. Another mitochondrial disease due to deficiency of the 5-methylaminomethyl-2-thiouridylate methyltransferase (TRMU) causes severe liver failure in infancy, but similar to the reversible mitochondrial myopathy, within the first year of life these infants may also recover completely. Partial recovery has been noted in some other rare forms of mitochondrial disease due to deficiency of mitochondrial tRNA synthetases and mitochondrial tRNA modifying enzymes. Here we summarize the clinical presentation of these unique reversible mitochondrial diseases and discuss potential molecular mechanisms behind the reversibility. Understanding these mechanisms may provide the key to treatments of potential broader relevance in mitochondrial disease, where for the majority of the patients no effective treatment is currently available.

Complex forms of mitochondrial DNA in human B cells transformed by Epstein-Barr virus (EBV)

DEFF Research Database (Denmark)

Christiansen, Gunna; Christiansen, C; Zeuthen, J

1983-01-01

Human lymphocytes and lymphoid cell lines were analyzed for the presence of complex forms of mitochondrial DNA (mtDNA) by electron microscopy. A high frequency (9%-14.5%) of catenated dimers, circular dimers, or oligomers were found in samples from Epstein-Barr-virus-(EBV) transformed lymphoblast......Human lymphocytes and lymphoid cell lines were analyzed for the presence of complex forms of mitochondrial DNA (mtDNA) by electron microscopy. A high frequency (9%-14.5%) of catenated dimers, circular dimers, or oligomers were found in samples from Epstein-Barr-virus-(EBV) transformed...

Oxidative stress negatively affects human sperm mitochondrial respiration.

Science.gov (United States)

Ferramosca, Alessandra; Pinto Provenzano, Sara; Montagna, Daniela Domenica; Coppola, Lamberto; Zara, Vincenzo

2013-07-01

To correlate the level of oxidative stress in serum and seminal fluid and the level of sperm deoxyribonucleic acid (DNA) fragmentation with sperm mitochondrial respiratory efficiency. Sperm mitochondrial respiratory activity was evaluated with a polarographic assay of oxygen consumption carried out in hypotonically treated sperm cells. A possible relationship between sperm mitochondrial respiratory efficiency, the level of oxidative stress, and the level of sperm DNA fragmentation was investigated. Sperm motility was positively correlated with mitochondrial respiration but negatively correlated with oxidative stress and DNA fragmentation. Interestingly, sperm mitochondrial respiratory activity was negatively affected by oxidative stress and DNA fragmentation. Our data indicate that sperm mitochondrial respiration is decreased in patients with high levels of reactive oxygen species by an uncoupling between electron transport and adenosine triphosphate synthesis. This reduction in mitochondrial functionality might be 1 of the reasons responsible for the decrease in spermatozoa motility. Copyright © 2013 Elsevier Inc. All rights reserved.

Mitochondrial DNA mutations in human tumor cells

OpenAIRE

LI, HUI; HONG, ZE-HUI

2012-01-01

Mitochondria play significant roles in cellular energy metabolism, free radical generation and apoptosis. The dysfunction of mitochondria is correlated with the origin and progression of tumors; thus, mutations in the mitochondrial genome that affect mitochondrial function may be one of the causal factors of tumorigenesis. Although the role of mitochondrial DNA (mtDNA) mutations in carcinogenesis has been investigated extensively by various approaches, the conclusions remain controversial to ...

Formation and Regulation of Mitochondrial Membranes

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Laila Cigana Schenkel

2014-01-01

Full Text Available Mitochondrial membrane phospholipids are essential for the mitochondrial architecture, the activity of respiratory proteins, and the transport of proteins into the mitochondria. The accumulation of phospholipids within mitochondria depends on a coordinate synthesis, degradation, and trafficking of phospholipids between the endoplasmic reticulum (ER and mitochondria as well as intramitochondrial lipid trafficking. Several studies highlight the contribution of dietary fatty acids to the remodeling of phospholipids and mitochondrial membrane homeostasis. Understanding the role of phospholipids in the mitochondrial membrane and their metabolism will shed light on the molecular mechanisms involved in the regulation of mitochondrial function and in the mitochondrial-related diseases.

Human papillomavirus molecular biology.

Science.gov (United States)

Harden, Mallory E; Munger, Karl

Human papillomaviruses are small DNA viruses with a tropism for squamous epithelia. A unique aspect of human papillomavirus molecular biology involves dependence on the differentiation status of the host epithelial cell to complete the viral lifecycle. A small group of these viruses are the etiologic agents of several types of human cancers, including oral and anogenital tract carcinomas. This review focuses on the basic molecular biology of human papillomaviruses. Copyright © 2016 Elsevier B.V. All rights reserved.

Explaining the imperfection of the molecular clock of hominid mitochondria.

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Eva-Liis Loogväli

Full Text Available The molecular clock of mitochondrial DNA has been extensively used to date various genetic events. However, its substitution rate among humans appears to be higher than rates inferred from human-chimpanzee comparisons, limiting the potential of interspecies clock calibrations for intraspecific dating. It is not well understood how and why the substitution rate accelerates. We have analyzed a phylogenetic tree of 3057 publicly available human mitochondrial DNA coding region sequences for changes in the ratios of mutations belonging to different functional classes. The proportion of non-synonymous and RNA genes substitutions has reduced over hundreds of thousands of years. The highest mutation ratios corresponding to fast acceleration in the apparent substitution rate of the coding sequence have occurred after the end of the Last Ice Age. We recalibrate the molecular clock of human mtDNA as 7990 years per synonymous mutation over the mitochondrial genome. However, the distribution of substitutions at synonymous sites in human data significantly departs from a model assuming a single rate parameter and implies at least 3 different subclasses of sites. Neutral model with 3 synonymous substitution rates can explain most, if not all, of the apparent molecular clock difference between the intra- and interspecies levels. Our findings imply the sluggishness of purifying selection in removing the slightly deleterious mutations from the human as well as the Neandertal and chimpanzee populations. However, for humans, the weakness of purifying selection has been further exacerbated by the population expansions associated with the out-of Africa migration and the end of the Last Ice Age.

Pathophysiology of mitochondrial lipid oxidation: Role of 4-hydroxynonenal (4-HNE) and other bioactive lipids in mitochondria.

Science.gov (United States)

Xiao, Mengqing; Zhong, Huiqin; Xia, Lin; Tao, Yongzhen; Yin, Huiyong

2017-10-01

Mitochondrial lipids are essential for maintaining the integrity of mitochondrial membranes and the proper functions of mitochondria. As the "powerhouse" of a cell, mitochondria are also the major cellular source of reactive oxygen species (ROS). Oxidative stress occurs when the antioxidant system is overwhelmed by overproduction of ROS. Polyunsaturated fatty acids in mitochondrial membranes are primary targets for ROS attack, which may lead to lipid peroxidation (LPO) and generation of reactive lipids, such as 4-hydroxynonenal. When mitochondrial lipids are oxidized, the integrity and function of mitochondria may be compromised and this may eventually lead to mitochondrial dysfunction, which has been associated with many human diseases including cancer, cardiovascular diseases, diabetes, and neurodegenerative diseases. How mitochondrial lipids are oxidized and the underlying molecular mechanisms and pathophysiological consequences associated with mitochondrial LPO remain poorly defined. Oxidation of the mitochondria-specific phospholipid cardiolipin and generation of bioactive lipids through mitochondrial LPO has been increasingly recognized as an important event orchestrating apoptosis, metabolic reprogramming of energy production, mitophagy, and immune responses. In this review, we focus on the current understanding of how mitochondrial LPO and generation of bioactive lipid mediators in mitochondria are involved in the modulation of mitochondrial functions in the context of relevant human diseases associated with oxidative stress. Copyright © 2017 Elsevier Inc. All rights reserved.

HmtDB 2016: data update, a better performing query system and human mitochondrial DNA haplogroup predictor.

Science.gov (United States)

Clima, Rosanna; Preste, Roberto; Calabrese, Claudia; Diroma, Maria Angela; Santorsola, Mariangela; Scioscia, Gaetano; Simone, Domenico; Shen, Lishuang; Gasparre, Giuseppe; Attimonelli, Marcella

2017-01-04

The HmtDB resource hosts a database of human mitochondrial genome sequences from individuals with healthy and disease phenotypes. The database is intended to support both population geneticists as well as clinicians undertaking the task to assess the pathogenicity of specific mtDNA mutations. The wide application of next-generation sequencing (NGS) has provided an enormous volume of high-resolution data at a low price, increasing the availability of human mitochondrial sequencing data, which called for a cogent and significant expansion of HmtDB data content that has more than tripled in the current release. We here describe additional novel features, including: (i) a complete, user-friendly restyling of the web interface, (ii) links to the command-line stand-alone and web versions of the MToolBox package, an up-to-date tool to reconstruct and analyze human mitochondrial DNA from NGS data and (iii) the implementation of the Reconstructed Sapiens Reference Sequence (RSRS) as mitochondrial reference sequence. The overall update renders HmtDB an even more handy and useful resource as it enables a more rapid data access, processing and analysis. HmtDB is accessible at http://www.hmtdb.uniba.it/. © The Author(s) 2016. Published by Oxford University Press on behalf of Nucleic Acids Research.

Evolution of the metazoan mitochondrial replicase.

Science.gov (United States)

Oliveira, Marcos T; Haukka, Jani; Kaguni, Laurie S

2015-03-03

The large number of complete mitochondrial DNA (mtDNA) sequences available for metazoan species makes it a good system for studying genome diversity, although little is known about the mechanisms that promote and/or are correlated with the evolution of this organellar genome. By investigating the molecular evolutionary history of the catalytic and accessory subunits of the mtDNA polymerase, pol γ, we sought to develop mechanistic insight into its function that might impact genome structure by exploring the relationships between DNA replication and animal mitochondrial genome diversity. We identified three evolutionary patterns among metazoan pol γs. First, a trend toward stabilization of both sequence and structure occurred in vertebrates, with both subunits evolving distinctly from those of other animal groups, and acquiring at least four novel structural elements, the most important of which is the HLH-3β (helix-loop-helix, 3 β-sheets) domain that allows the accessory subunit to homodimerize. Second, both subunits of arthropods and tunicates have become shorter and evolved approximately twice as rapidly as their vertebrate homologs. And third, nematodes have lost the gene for the accessory subunit, which was accompanied by the loss of its interacting domain in the catalytic subunit of pol γ, and they show the highest rate of molecular evolution among all animal taxa. These findings correlate well with the mtDNA genomic features of each group described above, and with their modes of DNA replication, although a substantive amount of biochemical work is needed to draw conclusive links regarding the latter. Describing the parallels between evolution of pol γ and metazoan mtDNA architecture may also help in understanding the processes that lead to mitochondrial dysfunction and to human disease-related phenotypes. © The Author(s) 2015. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

Bridging two scholarly islands enriches both: COI DNA barcodes for species identification versus human mitochondrial variation for the study of migrations and pathologies.

Science.gov (United States)

Thaler, David S; Stoeckle, Mark Y

2016-10-01

DNA barcodes for species identification and the analysis of human mitochondrial variation have developed as independent fields even though both are based on sequences from animal mitochondria. This study finds questions within each field that can be addressed by reference to the other. DNA barcodes are based on a 648-bp segment of the mitochondrially encoded cytochrome oxidase I. From most species, this segment is the only sequence available. It is impossible to know whether it fairly represents overall mitochondrial variation. For modern humans, the entire mitochondrial genome is available from thousands of healthy individuals. SNPs in the human mitochondrial genome are evenly distributed across all protein-encoding regions arguing that COI DNA barcode is representative. Barcode variation among related species is largely based on synonymous codons. Data on human mitochondrial variation support the interpretation that most - possibly all - synonymous substitutions in mitochondria are selectively neutral. DNA barcodes confirm reports of a low variance in modern humans compared to nonhuman primates. In addition, DNA barcodes allow the comparison of modern human variance to many other extant animal species. Birds are a well-curated group in which DNA barcodes are coupled with census and geographic data. Putting modern human variation in the context of intraspecies variation among birds shows humans to be a single breeding population of average variance.

Solid-state NMR, electrophysiology and molecular dynamics characterization of human VDAC2

International Nuclear Information System (INIS)

Gattin, Zrinka; Schneider, Robert; Laukat, Yvonne; Giller, Karin; Maier, Elke; Zweckstetter, Markus; Griesinger, Christian; Benz, Roland; Becker, Stefan; Lange, Adam

2015-01-01

The voltage-dependent anion channel (VDAC) is the most abundant protein of the outer mitochondrial membrane and constitutes the major pathway for the transport of ADP, ATP, and other metabolites. In this multidisciplinary study we combined solid-state NMR, electrophysiology, and molecular dynamics simulations, to study the structure of the human VDAC isoform 2 in a lipid bilayer environment. We find that the structure of hVDAC2 is similar to the structure of hVDAC1, in line with recent investigations on zfVDAC2. However, hVDAC2 appears to exhibit an increased conformational heterogeneity compared to hVDAC1 which is reflected in broader solid-state NMR spectra and less defined electrophysiological profiles

Solid-state NMR, electrophysiology and molecular dynamics characterization of human VDAC2

Energy Technology Data Exchange (ETDEWEB)

Gattin, Zrinka; Schneider, Robert; Laukat, Yvonne; Giller, Karin [Max Planck Institute for Biophysical Chemistry (Germany); Maier, Elke [Theodor-Boveri-Institut (Biozentrum) der Universität Würzburg, Lehrstuhl für Biotechnologie (Germany); Zweckstetter, Markus; Griesinger, Christian [Max Planck Institute for Biophysical Chemistry (Germany); Benz, Roland [Theodor-Boveri-Institut (Biozentrum) der Universität Würzburg, Lehrstuhl für Biotechnologie (Germany); Becker, Stefan; Lange, Adam, E-mail: alange@fmp-berlin.de [Max Planck Institute for Biophysical Chemistry (Germany)

2015-04-15

The voltage-dependent anion channel (VDAC) is the most abundant protein of the outer mitochondrial membrane and constitutes the major pathway for the transport of ADP, ATP, and other metabolites. In this multidisciplinary study we combined solid-state NMR, electrophysiology, and molecular dynamics simulations, to study the structure of the human VDAC isoform 2 in a lipid bilayer environment. We find that the structure of hVDAC2 is similar to the structure of hVDAC1, in line with recent investigations on zfVDAC2. However, hVDAC2 appears to exhibit an increased conformational heterogeneity compared to hVDAC1 which is reflected in broader solid-state NMR spectra and less defined electrophysiological profiles.

Identification of two products of mitochondrial protein synthesis associated with mitochondrial adenosine triphosphatase from Neurospora crassa

International Nuclear Information System (INIS)

Jackl, G.; Sebald, W.

1975-01-01

Soluble mitochondrial ATPase (F 1 ) isolated from Neurospora crassa is resolved by dodecyl-sulfate-gel electrophoresis into five polypeptide bands with apparent molecular weights of 59,000, 55,000, 36,000, 15,000 and 12,000. At least nine further polypeptides remain associated with ATPase after disintegration of mitochondria with Triton X-100 as shown by the analysis of an immunoprecipitate obtained with antiserum to F 1 ATPase. Two of the associated polypeptides with apparent molecular weights of 19,000 and 11,000 are translated on mitochondrial ribosomes, as demonstrated by incorporation in vivo of radioactive leucine in the presence of specific inhibitors of mitochondrial (chloramphenicol) and extramitochondrial (cycloheximide) protein synthesis. The appearance of mitochondrial translation products in the immunoprecipitated ATPase complex is inhibited by cycloheximide. The same applies for some of the extramitochondrial translation products in the presence of chloramphenicol. This suggests that both types of polypeptides are necessary for the assembly of the ATPase complex. (orig.) [de

Repeated static contractions increase mitochondrial vulnerability toward oxidative stress in human skeletal muscle

DEFF Research Database (Denmark)

Sahlin, Kent; Nielsen, Jens Steen; Mogensen, Martin

2006-01-01

Repeated static contractions (RSC) induce large fluctuations in tissue oxygen tension and increase the generation of reactive oxygen species (ROS). This study investigated the effect of RSC on muscle contractility, mitochondrial respiratory function, and in vitro sarcoplasmic reticulum (SR) Ca(2......+) kinetics in human muscle. Ten male subjects performed five bouts of static knee extension with 10-min rest in between. Each bout of RSC (target torque 66% of maximal voluntary contraction torque) was maintained to fatigue. Muscle biopsies were taken preexercise and 0.3 and 24 h postexercise from vastus...... lateralis. Mitochondria were isolated and respiratory function measured after incubation with H(2)O(2) (HPX) or control medium (Con). Mitochondrial function was not affected by RSC during Con. However, RSC exacerbated mitochondrial dysfunction during HPX, resulting in decreased respiratory control index...

Mitochondrial Morphology and Fundamental Parameters of the Mitochondrial Respiratory Chain Are Altered in Caenorhabditis elegans Strains Deficient in Mitochondrial Dynamics and Homeostasis Processes.

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Anthony L Luz

Full Text Available Mitochondrial dysfunction has been linked to myriad human diseases and toxicant exposures, highlighting the need for assays capable of rapidly assessing mitochondrial health in vivo. Here, using the Seahorse XFe24 Analyzer and the pharmacological inhibitors dicyclohexylcarbodiimide and oligomycin (ATP-synthase inhibitors, carbonyl cyanide 4-(trifluoromethoxy phenylhydrazone (mitochondrial uncoupler and sodium azide (cytochrome c oxidase inhibitor, we measured the fundamental parameters of mitochondrial respiratory chain function: basal oxygen consumption, ATP-linked respiration, maximal respiratory capacity, spare respiratory capacity and proton leak in the model organism Caenhorhabditis elegans. Since mutations in mitochondrial homeostasis genes cause mitochondrial dysfunction and have been linked to human disease, we measured mitochondrial respiratory function in mitochondrial fission (drp-1-, fusion (fzo-1-, mitophagy (pdr-1, pink-1-, and electron transport chain complex III (isp-1-deficient C. elegans. All showed altered function, but the nature of the alterations varied between the tested strains. We report increased basal oxygen consumption in drp-1; reduced maximal respiration in drp-1, fzo-1, and isp-1; reduced spare respiratory capacity in drp-1 and fzo-1; reduced proton leak in fzo-1 and isp-1; and increased proton leak in pink-1 nematodes. As mitochondrial morphology can play a role in mitochondrial energetics, we also quantified the mitochondrial aspect ratio for each mutant strain using a novel method, and for the first time report increased aspect ratios in pdr-1- and pink-1-deficient nematodes.

Molecular characterization of Echinococcus granulosus sensu stricto and Echinococcus canadensis in humans and livestock from Algeria.

Science.gov (United States)

Zait, Houria; Kouidri, Mokhtaria; Grenouillet, Florence Elisabeth; Umhang, Gérald; Millon, Laurence; Hamrioui, Boussad; Grenouillet, Frédéric

2016-06-01

In Algeria, previous studies investigated genotypes of Echinococcus granulosus sensu lato in animals and identified E. granulosus sensu stricto (s.s.) genotypes G1 and G3 whereas Echinococcus canadensis genotype G6 was only reported from dromedary cysts. Molecular data on human cystic echinococcosis (CE) were limited. We implemented a large genotyping study of hydatid cysts from humans and livestock animals to specify CE's molecular epidemiology and the genetic diversity in Algeria. Fifty-four human CE cysts from patients predominantly admitted in surgical units from Mustapha Hospital, Algiers, and 16 cysts from livestock animals gathered in two geographically distinct slaughterhouses, Tiaret and Tamanrasset, were collected. Molecular characterization was performed using sequencing of two mitochondrial genes, cytochrome c oxidase subunit I (COI) and NADH dehydrogenase subunit I (NDI). In humans, G1 of E. granulosus s.s. was the main genotype (90.7 %); four samples (7.4 %) were characterized as E. granulosus s.s. G3 and one cyst as E. canadensis G6 (1.8 %). This molecular confirmation of E. canadensis G6 human infection in Algeria was observed in a Tuareg female living in a desertic area in Tamanrasset. All cysts from sheep, cattle, and goat were identified as E. granulosus s.s. G1 and the two cysts originating from dromedary as E. canadensis G6. Twenty concatenated haplotypes (COI + NDI) were characterized. Among E. granulosus s.s., one haplotype (HL1) was highly predominant in both humans and animals cysts (71.6 %). This study revealed main occurrence of E. granulosus s.s. in humans and livestock animals, with description of a predominant shared haplotype corresponding to the main worldwide observed haplotype E.granulosus s.s. G1. E. canadensis G6 was limited to South Algeria, in dromedary as well as in human.

A mutation in the mitochondrial protein UQCRB promotes angiogenesis through the generation of mitochondrial reactive oxygen species

Energy Technology Data Exchange (ETDEWEB)

Chang, Junghwa [Chemical Genomics National Research Lab., Department of Biotechnology, Translational Research Center for Protein Function Control, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749 (Korea, Republic of); Jung, Hye Jin [Department of Pharmaceutical Engineering, Sun Moon University, Asansi, Chungnam 330-150 (Korea, Republic of); Jeong, Seung Hun; Kim, Hyoung Kyu; Han, Jin [National Research Laboratory for Mitochondrial Signaling, Department of Physiology, College of Medicine, Department of Health Sciences and Technology, Cardiovascular and Metabolic Disease Center, Inje University, Busan (Korea, Republic of); Kwon, Ho Jeong, E-mail: kwonhj@yonsei.ac.kr [Chemical Genomics National Research Lab., Department of Biotechnology, Translational Research Center for Protein Function Control, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749 (Korea, Republic of); Department of Internal Medicine, Yonsei University College of Medicine, Seoul 120-752 (Korea, Republic of)

2014-12-12

Highlights: • We constructed mitochondrial protein UQCRB mutant stable cell lines on the basis of a human case report. • These mutant cell lines exhibit pro-angiogenic activity with enhanced VEGF expression. • Proliferation of mutant cell lines was regulated by UQCRB inhibitors. • UQCRB may have a functional role in angiogenesis. - Abstract: Ubiquinol-cytochrome c reductase binding protein (UQCRB) is one of the subunits of mitochondrial complex III and is a target protein of the natural anti-angiogenic small molecule terpestacin. Previously, the biological role of UQCRB was thought to be limited to the maintenance of complex III. However, the identification and validation of UQCRB as a target protein of terpestacin enabled the role of UQCRB in oxygen sensing and angiogenesis to be elucidated. To explore the biological role of this protein further, UQCRB mutant stable cell lines were generated on the basis of a human case report. We demonstrated that these cell lines exhibited glycolytic and pro-angiogenic activities via mitochondrial reactive oxygen species (mROS)-mediated HIF1 signal transduction. Furthermore, a morphological abnormality in mitochondria was detected in UQCRB mutant stable cell lines. In addition, the proliferative effect of the UQCRB mutants was significantly regulated by the UQCRB inhibitors terpestacin and A1938. Collectively, these results provide a molecular basis for UQCRB-related biological processes and reveal potential key roles of UQCRB in angiogenesis and mitochondria-mediated metabolic disorders.

A mutation in the mitochondrial protein UQCRB promotes angiogenesis through the generation of mitochondrial reactive oxygen species

International Nuclear Information System (INIS)

Chang, Junghwa; Jung, Hye Jin; Jeong, Seung Hun; Kim, Hyoung Kyu; Han, Jin; Kwon, Ho Jeong

2014-01-01

Highlights: • We constructed mitochondrial protein UQCRB mutant stable cell lines on the basis of a human case report. • These mutant cell lines exhibit pro-angiogenic activity with enhanced VEGF expression. • Proliferation of mutant cell lines was regulated by UQCRB inhibitors. • UQCRB may have a functional role in angiogenesis. - Abstract: Ubiquinol-cytochrome c reductase binding protein (UQCRB) is one of the subunits of mitochondrial complex III and is a target protein of the natural anti-angiogenic small molecule terpestacin. Previously, the biological role of UQCRB was thought to be limited to the maintenance of complex III. However, the identification and validation of UQCRB as a target protein of terpestacin enabled the role of UQCRB in oxygen sensing and angiogenesis to be elucidated. To explore the biological role of this protein further, UQCRB mutant stable cell lines were generated on the basis of a human case report. We demonstrated that these cell lines exhibited glycolytic and pro-angiogenic activities via mitochondrial reactive oxygen species (mROS)-mediated HIF1 signal transduction. Furthermore, a morphological abnormality in mitochondria was detected in UQCRB mutant stable cell lines. In addition, the proliferative effect of the UQCRB mutants was significantly regulated by the UQCRB inhibitors terpestacin and A1938. Collectively, these results provide a molecular basis for UQCRB-related biological processes and reveal potential key roles of UQCRB in angiogenesis and mitochondria-mediated metabolic disorders

A chemical screen probing the relationship between mitochondrial content and cell size.

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Toshimori Kitami

Full Text Available The cellular content of mitochondria changes dynamically during development and in response to external stimuli, but the underlying mechanisms remain obscure. To systematically identify molecular probes and pathways that control mitochondrial abundance, we developed a high-throughput imaging assay that tracks both the per cell mitochondrial content and the cell size in confluent human umbilical vein endothelial cells. We screened 28,786 small molecules and observed that hundreds of small molecules are capable of increasing or decreasing the cellular content of mitochondria in a manner proportionate to cell size, revealing stereotyped control of these parameters. However, only a handful of compounds dissociate this relationship. We focus on one such compound, BRD6897, and demonstrate through secondary assays that it increases the cellular content of mitochondria as evidenced by fluorescence microscopy, mitochondrial protein content, and respiration, even after rigorous correction for cell size, cell volume, or total protein content. BRD6897 increases uncoupled respiration 1.6-fold in two different, non-dividing cell types. Based on electron microscopy, BRD6897 does not alter the percent of cytoplasmic area occupied by mitochondria, but instead, induces a striking increase in the electron density of existing mitochondria. The mechanism is independent of known transcriptional programs and is likely to be related to a blockade in the turnover of mitochondrial proteins. At present the molecular target of BRD6897 remains to be elucidated, but if identified, could reveal an important additional mechanism that governs mitochondrial biogenesis and turnover.

Molecular phylogeny of anoplocephalid tapeworms (Cestoda: Anoplocephalidae) infecting humans and non-human primates.

Science.gov (United States)

Doležalová, Jana; Vallo, Peter; Petrželková, Klára J; Foitová, Ivona; Nurcahyo, Wisnu; Mudakikwa, Antoine; Hashimoto, Chie; Jirků, Milan; Lukeš, Julius; Scholz, Tomáš; Modrý, David

2015-09-01

Anoplocephalid tapeworms of the genus Bertiella Stiles and Hassall, 1902 and Anoplocephala Blanchard, 1848, found in the Asian, African and American non-human primates are presumed to sporadic ape-to-man transmissions. Variable nuclear (5.8S-ITS2; 28S rRNA) and mitochondrial genes (cox1; nad1) of isolates of anoplocephalids originating from different primates (Callicebus oenanthe, Gorilla beringei, Gorilla gorilla, Pan troglodytes and Pongo abelii) and humans from various regions (South America, Africa, South-East Asia) were sequenced. In most analyses, Bertiella formed a monophyletic group within the subfamily Anoplocephalinae, however, the 28S rRNA sequence-based analysis indicated paraphyletic relationship between Bertiella from primates and Australian marsupials and rodents, which should thus be regarded as different taxa. Moreover, isolate determined as Anoplocephala cf. gorillae from mountain gorilla clustered within the Bertiella clade from primates. This either indicates that A. gorillae deserves to be included into the genus Bertiella, or, that an unknown Bertiella species infects also mountain gorillas. The analyses allowed the genetic differentiation of the isolates, albeit with no obvious geographical or host-related patterns. The unexpected genetic diversity of the isolates studied suggests the existence of several Bertiella species in primates and human and calls for revision of the whole group, based both on molecular and morphological data.

Targeted Transgenic Overexpression of Mitochondrial Thymidine Kinase (TK2) Alters Mitochondrial DNA (mtDNA) and Mitochondrial Polypeptide Abundance : Transgenic TK2, mtDNA, and Antiretrovirals

OpenAIRE

Hosseini, Seyed H.; Kohler, James J.; Haase, Chad P.; Tioleco, Nina; Stuart, Tami; Keebaugh, Erin; Ludaway, Tomika; Russ, Rodney; Green, Elgin; Long, Robert; Wang, Liya; Eriksson, Staffan; Lewis, William

2007-01-01

Mitochondrial toxicity limits nucleoside reverse transcriptase inhibitors (NRTIs) for acquired immune deficiency syndrome. NRTI triphosphates, the active moieties, inhibit human immunodeficiency virus reverse transcriptase and eukaryotic mitochondrial DNA polymerase pol-γ. NRTI phosphorylation seems to correlate with mitochondrial toxicity, but experimental evidence is lacking. Transgenic mice (TGs) with cardiac overexpression of thymidine kinase isoforms (mitochondrial TK2 and cytoplasmic TK...

Tributyltin induces mitochondrial fission through Mfn1 degradation in human induced pluripotent stem cells.

Science.gov (United States)

Yamada, Shigeru; Asanagi, Miki; Hirata, Naoya; Itagaki, Hiroshi; Sekino, Yuko; Kanda, Yasunari

2016-08-01

Organotin compounds, such as tributyltin (TBT), are well-known endocrine disruptors. TBT is also known to cause various forms of cytotoxicity, including neurotoxicity and immunotoxicity. However, TBT toxicity has not been identified in normal stem cells. In the present study, we examined the effects of TBT on cell growth in human induced pluripotent stem cells (iPSCs). We found that exposure to nanomolar concentrations of TBT decreased intracellular ATP levels and inhibited cell viability in iPSCs. Because TBT suppressed energy production, which is a critical function of the mitochondria, we further assessed the effects of TBT on mitochondrial dynamics. Staining with MitoTracker revealed that nanomolar concentrations of TBT induced mitochondrial fragmentation. TBT also reduced the expression of mitochondrial fusion protein mitofusin 1 (Mfn1), and this effect was abolished by knockdown of the E3 ubiquitin ligase membrane-associated RING-CH 5 (MARCH5), suggesting that nanomolar concentrations of TBT could induce mitochondrial dysfunction via MARCH5-mediated Mfn1 degradation in iPSCs. Thus, mitochondrial function in normal stem cells could be used to assess cytotoxicity associated with metal exposure. Copyright © 2016 Elsevier Ltd. All rights reserved.

A role for mitochondrial oxidants in stress-induced premature senescence of human vascular smooth muscle cells

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Yogita Mistry

2013-01-01

Full Text Available Mitochondria are a major source of cellular oxidants and have been implicated in aging and associated pathologies, notably cardiovascular diseases. Vascular cell senescence is observed in experimental and human cardiovascular pathologies. Our previous data highlighted a role for angiotensin II in the induction of telomere-dependent and -independent premature senescence of human vascular smooth muscle cells and suggested this was due to production of superoxide by NADPH oxidase. However, since a role for mitochondrial oxidants was not ruled out we hypothesise that angiotensin II mediates senescence by mitochondrial superoxide generation and suggest that inhibition of superoxide may prevent vascular smooth muscle cell aging in vitro. Cellular senescence was induced using a stress-induced premature senescence protocol consisting of three successive once-daily exposure of cells to 1×10−8 mol/L angiotensin II and was dependent upon the type-1 angiotensin II receptor. Angiotensin stimulated NADPH-dependent superoxide production as estimated using lucigenin chemiluminescence in cell lysates and this was attenuated by the mitochondrial electron transport chain inhibitor, rotenone. Angiotensin also resulted in an increase in mitoSOX fluorescence indicating stimulation of mitochondrial superoxide. Significantly, the induction of senescence by angiotensin II was abrogated by rotenone and by the mitochondria-targeted superoxide dismutase mimetic, mitoTEMPO. These data suggest that mitochondrial superoxide is necessary for the induction of stress-induced premature senescence by angiotensin II and taken together with other data suggest that mitochondrial cross-talk with NADPH oxidases, via as yet unidentified signalling pathways, is likely to play a key role.

Mitochondrial DAMPs induce endotoxin tolerance in human monocytes: an observation in patients with myocardial infarction.

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Irene Fernández-Ruiz

Full Text Available Monocyte exposure to mitochondrial Danger Associated Molecular Patterns (DAMPs, including mitochondrial DNA (mtDNA, induces a transient state in which these cells are refractory to further endotoxin stimulation. In this context, IRAK-M up-regulation and impaired p65 activity were observed. This phenomenon, termed endotoxin tolerance (ET, is characterized by decreased production of cytokines in response to the pro-inflammatory stimulus. We also show that monocytes isolated from patients with myocardial infarction (MI exhibited high levels of circulating mtDNA, which correlated with ET status. Moreover, a significant incidence of infection was observed in those patients with a strong tolerant phenotype. The present data extend our current understanding of the implications of endotoxin tolerance. Furthermore, our data suggest that the levels of mitochondrial antigens in plasma, such as plasma mtDNA, should be useful as a marker of increased risk of susceptibility to nosocomial infections in MI and in other pathologies involving tissue damage.

Important mitochondrial proteins in human omental adipose tissue show reduced expression in obesity.

Science.gov (United States)

Lindinger, Peter W; Christe, Martine; Eberle, Alex N; Kern, Beatrice; Peterli, Ralph; Peters, Thomas; Jayawardene, Kamburapola J I; Fearnley, Ian M; Walker, John E

2015-09-01

Obesity is associated with impaired mitochondrial function. This study compares mitochondrial protein expression in omental fat in obese and non-obese humans. Omental adipose tissue was obtained by surgical biopsy, adipocytes were purified and mitochondria isolated. Using anion-exchange chromatography, SDS-PAGE and mass-spectrometry, 128 proteins with potentially different abundances in patient groups were identified, 62 of the 128 proteins are mainly localized in the mitochondria. Further quantification of 12 of these 62 proteins by immune dot blot analysis revealed four proteins citrate synthase, HADHA, LETM1 and mitofilin being inversely associated with BMI, and mitofilin being inversely correlated with gender.

Doxycycline Impairs Mitochondrial Function and Protects Human Glioma Cells from Hypoxia-Induced Cell Death: Implications of Using Tet-Inducible Systems.

Science.gov (United States)

Luger, Anna-Luisa; Sauer, Benedikt; Lorenz, Nadja I; Engel, Anna L; Braun, Yannick; Voss, Martin; Harter, Patrick N; Steinbach, Joachim P; Ronellenfitsch, Michael W

2018-05-17

Inducible gene expression is an important tool in molecular biology research to study protein function. Most frequently, the antibiotic doxycycline is used for regulation of so-called tetracycline (Tet)-inducible systems. In contrast to stable gene overexpression, these systems allow investigation of acute and reversible effects of cellular protein induction. Recent reports have already called for caution when using Tet-inducible systems as the employed antibiotics can disturb mitochondrial function and alter cellular metabolism by interfering with mitochondrial translation. Reprogramming of energy metabolism has lately been recognized as an important emerging hallmark of cancer and is a central focus of cancer research. Therefore, the scope of this study was to systematically analyze dose-dependent metabolic effects of doxycycline on a panel of glioma cell lines with concomitant monitoring of gene expression from Tet-inducible systems. We report that doxycycline doses commonly used with inducible expression systems (0.01⁻1 µg/mL) substantially alter cellular metabolism: Mitochondrial protein synthesis was inhibited accompanied by reduced oxygen and increased glucose consumption. Furthermore, doxycycline protected human glioma cells from hypoxia-induced cell death. An impairment of cell growth was only detectable with higher doxycycline doses (10 µg/mL). Our findings describe settings where doxycycline exerts effects on eukaryotic cellular metabolism, limiting the employment of Tet-inducible systems.

Mitochondrial protein acetylation mediates nutrient sensing of mitochondrial protein synthesis and mitonuclear protein balance.

Science.gov (United States)

Di Domenico, Antonella; Hofer, Annette; Tundo, Federica; Wenz, Tina

2014-11-01

Changes in nutrient supply require global metabolic reprogramming to optimize the utilization of the nutrients. Mitochondria as a central component of the cellular metabolism play a key role in this adaptive process. Since mitochondria harbor their own genome, which encodes essential enzymes, mitochondrial protein synthesis is a determinant of metabolic adaptation. While regulation of cytoplasmic protein synthesis in response to metabolic challenges has been studied in great detail, mechanisms which adapt mitochondrial translation in response to metabolic challenges remain elusive. Our results suggest that the mitochondrial acetylation status controlled by Sirt3 and its proposed opponent GCN5L1 is an important regulator of the metabolic adaptation of mitochondrial translation. Moreover, both proteins modulate regulators of cytoplasmic protein synthesis as well as the mitonuclear protein balance making Sirt3 and GCN5L1 key players in synchronizing mitochondrial and cytoplasmic translation. Our results thereby highlight regulation of mitochondrial translation as a novel component in the cellular nutrient sensing scheme and identify mitochondrial acetylation as a new regulatory principle for the metabolic competence of mitochondrial protein synthesis. © 2014 International Union of Biochemistry and Molecular Biology.

Shifting the balance of mitochondrial apoptosis: therapeutic perspectives

International Nuclear Information System (INIS)

Fulda, Simone

2012-01-01

Signaling via the intrinsic (mitochondrial) pathway of apoptosis represents one of the critical signal transduction cascades that control the regulation of cell death. This pathway is typically altered in human cancers, thereby providing a suitable target for therapeutic intervention. Members of the Bcl-2 family of proteins as well as cell survival signaling cascades such as the PI3K/Akt/mTOR pathway are involved in the regulation of mitochondria-mediated apoptosis. Therefore, further insights into the molecular mechanisms that form the basis for the control of mitochondria-mediated apoptosis will likely open new perspectives to bypass evasion of apoptosis and treatment resistance in human cancers.

Shifting the balance of mitochondrial apoptosis: therapeutic perspectives

Energy Technology Data Exchange (ETDEWEB)

Fulda, Simone, E-mail: simone.fulda@kgu.de [Institute for Experimental Cancer Research in Pediatrics, Goethe-University, Frankfurt (Germany)

2012-10-08

Signaling via the intrinsic (mitochondrial) pathway of apoptosis represents one of the critical signal transduction cascades that control the regulation of cell death. This pathway is typically altered in human cancers, thereby providing a suitable target for therapeutic intervention. Members of the Bcl-2 family of proteins as well as cell survival signaling cascades such as the PI3K/Akt/mTOR pathway are involved in the regulation of mitochondria-mediated apoptosis. Therefore, further insights into the molecular mechanisms that form the basis for the control of mitochondria-mediated apoptosis will likely open new perspectives to bypass evasion of apoptosis and treatment resistance in human cancers.

Shifting the balance of mitochondrial apoptosis: therapeutic perspectives

Directory of Open Access Journals (Sweden)

Simone eFulda

2012-10-01

Full Text Available Signaling via the intrinsic (mitochondrial pathway of apoptosis represents one of the critical signal transduction cascades that control the regulation of cell death. This pathway is typically altered in human cancers, thereby providing a suitable target for therapeutic intervention. Members of the Bcl-2 family of proteins as well as cell survival signaling cascades such as the PI3K/Akt/mTOR pathway are involved in the regulation of mitochondria-mediated apoptosis. Therefore, further insights into the molecular mechanisms that form the basis for the control of mitochondria-mediated apoptosis will likely open new perspectives to bypass evasion of apoptosis and treatment resistance in human cancers.

Mitochondrial cardiomyopathies

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Ayman W. El-Hattab

2016-07-01

Full Text Available Mitochondria are found in all nucleated human cells and perform a variety of essential functions, including the generation of cellular energy. Mitochondria are under dual genome control. Only a small fraction of their proteins are encoded by mitochondrial DNA (mtDNA while more than 99% of them are encoded by nuclear DNA (nDNA. Mutations in mtDNA or mitochondria-related nDNA genes result in mitochondrial dysfunction leading to insufficient energy production required to meet the needs of various organs, particularly those with high energy requirements, including the central nervous system, skeletal and cardiac muscles, kidneys, liver, and endocrine system. Because cardiac muscles are one of the high energy demanding tissues, cardiac involvement occurs in mitochondrial diseases with cardiomyopathies being one of the most frequent cardiac manifestations found in these disorders. Cardiomyopathy is estimated to occur in 20-40% of children with mitochondrial diseases. Mitochondrial cardiomyopathies can vary in severity from asymptomatic status to severe manifestations including heart failure, arrhythmias, and sudden cardiac death. Hypertrophic cardiomyopathy is the most common type; however, mitochondrial cardiomyopathies might also present as dilated, restrictive, left ventricular noncompaction, and histiocytoid cardiomyopathies. Cardiomyopathies are frequent manifestations of mitochondrial diseases associated with defects in electron transport chain (ETC complexes subunits and their assembly factors, mitochondrial tRNAs, rRNAs, ribosomal proteins, and translation factors, mtDNA maintenance, and coenzyme Q10 synthesis. Other mitochondrial diseases with cardiomyopathies include Barth syndrome, Sengers syndrome, TMEM70-related mitochondrial complex V deficiency, and Friedreich ataxia.

Lactate dehydrogenase is not a mitochondrial enzyme in human and mouse vastus lateralis muscle

DEFF Research Database (Denmark)

Rasmussen, Hans N; van Hall, Gerrit; Rasmussen, Ulla F

2002-01-01

The presence of lactate dehydrogenase in skeletal muscle mitochondria was investigated to clarify whether lactate is a possible substrate for mitochondrial respiration. Mitochondria were prepared from 100 mg samples of human and mouse vastus lateralis muscle. All fractions from the preparation...... procedure were assayed for marker enzymes and lactate dehydrogenase (LDH). The mitochondrial fraction contained no LDH activity (detection limit approximately 0.05 % of the tissue activity) and the distribution of LDH activity among the fractions paralleled that of pyruvate kinase, i.e. LDH was fractionated...... as a cytoplasmic enzyme. Respiratory experiments with the mitochondrial fraction also indicated the absence of LDH. Lactate did not cause respiration, nor did it affect the respiration of pyruvate + malate. The major part of the native cytochrome c was retained in the isolated mitochondria, which, furthermore...

PGC-1α-Dependent Mitochondrial Adaptation Is Necessary to Sustain IL-2-Induced Activities in Human NK Cells.

Science.gov (United States)

Miranda, Dante; Jara, Claudia; Ibañez, Jorge; Ahumada, Viviana; Acuña-Castillo, Claudio; Martin, Adrian; Córdova, Alexandra; Montoya, Margarita

2016-01-01

Human Natural Killer (NK) cells are a specialized heterogeneous subpopulation of lymphocytes involved in antitumor defense reactions. NK cell effector functions are critically dependent on cytokines and metabolic activity. Among various cytokines modulating NK cell function, interleukin-2 (IL-2) can induce a more potent cytotoxic activity defined as lymphokine activated killer activity (LAK). Our aim was to determine if IL-2 induces changes at the mitochondrial level in NK cells to support the bioenergetic demand for performing this enhanced cytotoxic activity more efficiently. Purified human NK cells were cultured with high IL-2 concentrations to develop LAK activity, which was assessed by the ability of NK cells to lyse NK-resistant Daudi cells. Here we show that, after 72 h of culture of purified human NK cells with enough IL-2 to induce LAK activity, both the mitochondrial mass and the mitochondrial membrane potential increased in a PGC-1α-dependent manner. In addition, oligomycin, an inhibitor of ATP synthase, inhibited IL-2-induced LAK activity at 48 and 72 h of culture. Moreover, the secretion of IFN-γ from NK cells with LAK activity was also partially dependent on PGC-1α expression. These results indicate that PGC-1α plays a crucial role in regulating mitochondrial function involved in the maintenance of LAK activity in human NK cells stimulated with IL-2.

Mitochondrial respiratory efficiency is positively correlated with human sperm motility.

Science.gov (United States)

Ferramosca, Alessandra; Provenzano, Sara Pinto; Coppola, Lamberto; Zara, Vincenzo

2012-04-01

To correlate sperm mitochondrial respiratory efficiency with variations in sperm motility and with sperm morphologic anomalies. Sperm mitochondrial respiratory activity was evaluated with a polarographic assay of oxygen consumption carried out in hypotonically-treated sperm cells. A possible relationship among sperm mitochondrial respiratory efficiency, sperm motility, and morphologic anomalies was investigated. Mitochondrial respiratory efficiency was positively correlated with sperm motility and negatively correlated with the percentage of immotile spermatozoa. Moreover, midpiece defects impaired mitochondrial functionality. Our data indicate that an increase in sperm motility requires a parallel increase in mitochondrial respiratory capacity, thereby supporting the fundamental role played by mitochondrial oxidative phosphorylation in sperm motility of normozoospermic subjects. These results are of physiopathological relevance because they suggest that disturbances of sperm mitochondrial function and of energy production could be responsible for asthenozoospermia. Copyright © 2012 Elsevier Inc. All rights reserved.

Age-Associated Impairments in Mitochondrial ADP Sensitivity Contribute to Redox Stress in Senescent Human Skeletal Muscle

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Graham P. Holloway

2018-03-01

Full Text Available Summary: It remains unknown if mitochondrial bioenergetics are altered with aging in humans. We established an in vitro method to simultaneously determine mitochondrial respiration and H2O2 emission in skeletal muscle tissue across a range of biologically relevant ADP concentrations. Using this approach, we provide evidence that, although the capacity for mitochondrial H2O2 emission is not increased with aging, mitochondrial ADP sensitivity is impaired. This resulted in an increase in mitochondrial H2O2 and the fraction of electron leak to H2O2, in the presence of virtually all ADP concentrations examined. Moreover, although prolonged resistance training in older individuals increased muscle mass, strength, and maximal mitochondrial respiration, exercise training did not alter H2O2 emission rates in the presence of ADP, the fraction of electron leak to H2O2, or the redox state of the muscle. These data establish that a reduction in mitochondrial ADP sensitivity increases mitochondrial H2O2 emission and contributes to age-associated redox stress. : Holloway et al. show that an inability of ADP to decrease mitochondrial reactive oxygen species emission contributes to redox stress in skeletal muscle tissue of older individuals and that this process is not recovered following prolonged resistance-type exercise training, despite the general benefits of resistance training for muscle health. Keywords: mitochondria, aging, muscle, ROS, H2O2, ADP, respiration, bioenergetics, exercise, resistance training

Importance of mitochondrial calcium uniporter in high glucose-induced endothelial cell dysfunction.

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Chen, Wei; Yang, Jie; Chen, Shuhua; Xiang, Hong; Liu, Hengdao; Lin, Dan; Zhao, Shaoli; Peng, Hui; Chen, Pan; Chen, Alex F; Lu, Hongwei

2017-11-01

Mitochondrial Ca 2+ overload is implicated in hyperglycaemia-induced endothelial cell dysfunction, but the key molecular events responsible remain unclear. We examined the involvement of mitochondrial calcium uniporter, which mediates mitochondrial Ca 2+ uptake, in endothelial cell dysfunction resulting from high-glucose treatment. Human umbilical vein endothelial cells were exposed to various glucose concentrations and to high glucose (30 mM) following mitochondrial calcium uniporter inhibition or activation with ruthenium red and spermine, respectively. Subsequently, mitochondrial calcium uniporter and mitochondrial calcium uniporter regulator 1 messenger RNA and protein expression was measured by real-time polymerase chain reaction and western blotting. Ca 2+ concentrations were analysed by laser confocal microscopy, and cytoplasmic and mitochondrial oxidative stress was detected using 2',7'-dichlorofluorescein diacetate and MitoSOX Red, respectively. Apoptosis was assessed by annexin V-fluorescein isothiocyanate/propidium iodide staining, and a wound-healing assay was performed using an in vitro model. High glucose markedly upregulated mitochondrial calcium uniporter and mitochondrial calcium uniporter regulator 1 messenger RNA expression, as well as protein production, in a dose- and time-dependent manner with a maximum effect demonstrated at 72 h and 30 mM glucose concentration. Moreover, high-glucose treatment significantly raised both mitochondrial and cytoplasmic Ca 2+ and reactive oxygen species levels, increased apoptosis and compromised wound healing (all p calcium uniporter, respectively. Mitochondrial calcium uniporter plays an important role in hyperglycaemia-induced endothelial cell dysfunction and may constitute a therapeutic target to reduce vascular complications in diabetes.

Cathepsin E promotes pulmonary emphysema via mitochondrial fission.

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Zhang, Xuchen; Shan, Peiying; Homer, Robert; Zhang, Yi; Petrache, Irina; Mannam, Praveen; Lee, Patty J

2014-10-01

Emphysema is characterized by loss of lung elasticity and irreversible air space enlargement, usually in the later decades of life. The molecular mechanisms of emphysema remain poorly defined. We identified a role for a novel cathepsin, cathepsin E, in promoting emphysema by inducing mitochondrial fission. Unlike previously reported cysteine cathepsins, which have been implicated in cigarette smoke-induced lung disease, cathepsin E is a nonlysosomal intracellular aspartic protease whose function has been described only in antigen processing. We examined lung tissue sections of persons with chronic obstructive pulmonary disease, a clinical entity that includes emphysematous change. Human chronic obstructive pulmonary disease lungs had markedly increased cathepsin E protein in the lung epithelium. We generated lung epithelial-targeted transgenic cathepsin E mice and found that they develop emphysema. Overexpression of cathepsin E resulted in increased E3 ubiquitin ligase parkin, mitochondrial fission protein dynamin-related protein 1, caspase activation/apoptosis, and ultimately loss of lung parenchyma resembling emphysema. Inhibiting dynamin-related protein 1, using a small molecule inhibitor in vitro or in vivo, inhibited cathepsin E-induced apoptosis and emphysema. To the best of our knowledge, our study is the first to identify links between cathepsin E, mitochondrial fission, and caspase activation/apoptosis in the pathogenesis of pulmonary emphysema. Our data expand the current understanding of molecular mechanisms of emphysema development and may provide new therapeutic targets. Copyright © 2014 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.

PINK1 regulates mitochondrial trafficking in dendrites of cortical neurons through mitochondrial PKA.

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Das Banerjee, Tania; Dagda, Raul Y; Dagda, Marisela; Chu, Charleen T; Rice, Monica; Vazquez-Mayorga, Emmanuel; Dagda, Ruben K

2017-08-01

Mitochondrial Protein Kinase A (PKA) and PTEN-induced kinase 1 (PINK1), which is linked to Parkinson's disease, are two neuroprotective serine/threonine kinases that regulate dendrite remodeling and mitochondrial function. We have previously shown that PINK1 regulates dendrite morphology by enhancing PKA activity. Here, we show the molecular mechanisms by which PINK1 and PKA in the mitochondrion interact to regulate dendrite remodeling, mitochondrial morphology, content, and trafficking in dendrites. PINK1-deficient cortical neurons exhibit impaired mitochondrial trafficking, reduced mitochondrial content, fragmented mitochondria, and a reduction in dendrite outgrowth compared to wild-type neurons. Transient expression of wild-type, but not a PKA-binding-deficient mutant of the PKA-mitochondrial scaffold dual-specificity A Kinase Anchoring Protein 1 (D-AKAP1), restores mitochondrial trafficking, morphology, and content in dendrites of PINK1-deficient cortical neurons suggesting that recruiting PKA to the mitochondrion reverses mitochondrial pathology in dendrites induced by loss of PINK1. Mechanistically, full-length and cleaved forms of PINK1 increase the binding of the regulatory subunit β of PKA (PKA/RIIβ) to D-AKAP1 to enhance the autocatalytic-mediated phosphorylation of PKA/RIIβ and PKA activity. D-AKAP1/PKA governs mitochondrial trafficking in dendrites via the Miro-2/TRAK2 complex and by increasing the phosphorylation of Miro-2. Our study identifies a new role of D-AKAP1 in regulating mitochondrial trafficking through Miro-2, and supports a model in which PINK1 and mitochondrial PKA participate in a similar neuroprotective signaling pathway to maintain dendrite connectivity. © 2017 International Society for Neurochemistry.

A role for human mitochondrial complex II in the production of reactive oxygen species in human skin

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Alasdair Anderson

2014-01-01

Full Text Available The mitochondrial respiratory chain is a major generator of cellular oxidative stress, thought to be an underlying cause of the carcinogenic and ageing process in many tissues including skin. Previous studies of the relative contributions of the respiratory chain (RC complexes I, II and III towards production of reactive oxygen species (ROS have focussed on rat tissues and certainly not on human skin which is surprising as this tissue is regularly exposed to UVA in sunlight, a potent generator of cellular oxidative stress. In a novel approach we have used an array of established specific metabolic inhibitors and DHR123 fluorescence to study the relative roles of the mitochondrial RC complexes in cellular ROS production in 2 types of human skin cells. These include additional enhancement of ROS production by exposure to physiological levels of UVA. The effects within epidermal and dermal derived skin cells are compared to other tissue cell types as well as those harbouring a compromised mitochondrial status (Rho-zero A549. The results show that the complex II inhibitor, TTFA, was the only RC inhibitor to significantly increase UVA-induced ROS production in both skin cell types (P<0.05 suggesting that the role of human skin complex II in terms of influencing ROS production is more important than previously thought particularly in comparison to liver cells. Interestingly, two-fold greater maximal activity of complex II enzyme was observed in both skin cell types compared to liver (P<0.001. The activities of RC enzymes appear to decrease with increasing age and telomere length is correlated with ageing. Our study showed that the level of maximal complex II activity was higher in the MRC5/hTERT (human lung fibroblasts transfected with telomerase cells than the corresponding wild type cells (P=0.0012 which can be considered (in terms of telomerase activity as models of younger and older cells respectively.

Important mitochondrial proteins in human omental adipose tissue show reduced expression in obesity

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Peter W. Lindinger

2015-09-01

Full Text Available Obesity is associated with impaired mitochondrial function. This study compares mitochondrial protein expression in omental fat in obese and non-obese humans. Omental adipose tissue was obtained by surgical biopsy, adipocytes were purified and mitochondria isolated. Using anion-exchange chromatography, SDS-PAGE and mass-spectrometry, 128 proteins with potentially different abundances in patient groups were identified, 62 of the 128 proteins are mainly localized in the mitochondria. Further quantification of 12 of these 62 proteins by immune dot blot analysis revealed four proteins citrate synthase, HADHA, LETM1 and mitofilin being inversely associated with BMI, and mitofilin being inversely correlated with gender.

Role of mitochondrial permeability transition in human renal tubular epithelial cell death induced by aristolochic acid

International Nuclear Information System (INIS)

Qi Xinming; Cai Yan; Gong Likun; Liu Linlin; Chen Fangping; Xiao Ying; Wu Xiongfei; Li Yan; Xue Xiang; Ren Jin

2007-01-01

Aristolochic acid (AA), a natural nephrotoxin and carcinogen, can induce a progressive tubulointerstitial nephropathy. However, the mechanism by which AA causes renal injury remains largely unknown. Here we reported that the mitochondrial permeability transition (MPT) plays an important role in the renal injury induced by aristolochic acid I (AAI). We found that in the presence of Ca 2+ , AAI caused mitochondrial swelling, leakage of Ca 2+ , membrane depolarization, and release of cytochrome c in isolated kidney mitochondria. These alterations were suppressed by cyclosporin A (CsA), an agent known to inhibit MPT. Culture of HK-2 cell, a human renal tubular epithelial cell line for 24 h with AAI caused a decrease in cellular ATP, mitochondrial membrane depolarization, cytochrome c release, and increase of caspase 3 activity. These toxic effects of AAI were attenuated by CsA and bongkrekic acid (BA), another specific MPT inhibitor. Furthermore, AAI greatly inhibited the activity of mitochondrial adenine nucleotide translocator (ANT) in isolated mitochondria. We suggested that ANT may mediate, at least in part, the AAI-induced MPT. Taken together, these results suggested that MPT plays a critical role in the pathogenesis of HK-2 cell injury induced by AAI and implied that MPT might contribute to human nephrotoxicity of aristolochic acid

Cytosolic calcium mediates RIP1/RIP3 complex-dependent necroptosis through JNK activation and mitochondrial ROS production in human colon cancer cells.

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Sun, Wen; Wu, Xiaxia; Gao, Hongwei; Yu, Jie; Zhao, Wenwen; Lu, Jin-Jian; Wang, Jinhua; Du, Guanhua; Chen, Xiuping

2017-07-01

accumulation is a critical mediator in MAM-induced necroptosis through sustained JNK activation and mitochondrial ROS production. Our study also provided new insights into the molecular regulation of necroptosis in human colon cancer cells. Copyright © 2017 Elsevier Inc. All rights reserved.

Identification of the polypeptides encoded in the unassigned reading frames 2, 4, 4L, and 5 of human mitochondrial DNA

International Nuclear Information System (INIS)

Mariottini, P.; Chomyn, A.; Riley, M.; Cottrell, B.; Doolittle, R.F.; Attardi, G.

1986-01-01

In previous work, antibodies prepared against chemically synthesized peptides predicted from the DNA sequence were used to identify the polypeptides encoded in three of the eight unassigned reading frames (URFs) of human mitochondrial DNA (mtDNA). In the present study, this approach has been extended to other human mtDNA URFs. In particular, antibodies directed against the NH 2 -terminal octapeptide of the putative URF2 product specifically precipitated component 11 of the HeLa cell mitochondrial translation products, the reaction being inhibited by the specific peptide. Similarly, antibodies directed against the COOH-terminal nonapeptide of the putative URF4 product reacted specifically with components 4 and 5, and antibodies against a COOH-terminal heptapeptide of the presumptive URF4L product reacted specifically with component 26. Antibodies against the NH 2 -terminal heptapeptide of the putative product of URF5 reacted with component 1, but only to a marginal extent; however, the results of a trypsin fingerprinting analysis of component 1 point strongly to this component as being the authentic product of URF5. The polypeptide assignments to the mtDNA URFs analyzed here are supported by the relative electrophoretic mobilities of proteins 11, 4-5, 26, and 1, which are those expected for the molecular weights predicted from the DNA sequence for the products of URF2, URF4, URF4L, and URF5, respectively. With the present assignment, seven of the eight human mtDNA URFs have been shown to be expressed in HeLa cells

Mitochondrial pharmacology: electron transport chain bypass as strategies to treat mitochondrial dysfunction.

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Atamna, Hani; Mackey, Jeanette; Dhahbi, Joseph M

2012-01-01

Mitochondrial dysfunction (primary or secondary) is detrimental to intermediary metabolism. Therapeutic strategies to treat/prevent mitochondrial dysfunction could be valuable for managing metabolic and age-related disorders. Here, we review strategies proposed to treat mitochondrial impairment. We then concentrate on redox-active agents, with mild-redox potential, who shuttle electrons among specific cytosolic or mitochondrial redox-centers. We propose that specific redox agents with mild redox potential (-0.1 V; 0.1 V) improve mitochondrial function because they can readily donate or accept electrons in biological systems, thus they enhance metabolic activity and prevent reactive oxygen species (ROS) production. These agents are likely to lack toxic effects because they lack the risk of inhibiting electron transfer in redox centers. This is different from redox agents with strong negative (-0.4 V; -0.2 V) or positive (0.2 V; 0.4 V) redox potentials who alter the redox status of redox-centers (i.e., become permanently reduced or oxidized). This view has been demonstrated by testing the effect of several redox active agents on cellular senescence. Methylene blue (MB, redox potential ≅10 mV) appears to readily cycle between the oxidized and reduced forms using specific mitochondrial and cytosolic redox centers. MB is most effective in delaying cell senescence and enhancing mitochondrial function in vivo and in vitro. Mild-redox agents can alter the biochemical activity of specific mitochondrial components, which then in response alters the expression of nuclear and mitochondrial genes. We present the concept of mitochondrial electron-carrier bypass as a potential result of mild-redox agents, a method to prevent ROS production, improve mitochondrial function, and delay cellular aging. Thus, mild-redox agents may prevent/delay mitochondria-driven disorders. Copyright © 2012 International Union of Biochemistry and Molecular Biology, Inc.

Evolution of gastropod mitochondrial genome arrangements

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Zardoya Rafael

2008-02-01

Full Text Available Abstract Background Gastropod mitochondrial genomes exhibit an unusually great variety of gene orders compared to other metazoan mitochondrial genome such as e.g those of vertebrates. Hence, gastropod mitochondrial genomes constitute a good model system to study patterns, rates, and mechanisms of mitochondrial genome rearrangement. However, this kind of evolutionary comparative analysis requires a robust phylogenetic framework of the group under study, which has been elusive so far for gastropods in spite of the efforts carried out during the last two decades. Here, we report the complete nucleotide sequence of five mitochondrial genomes of gastropods (Pyramidella dolabrata, Ascobulla fragilis, Siphonaria pectinata, Onchidella celtica, and Myosotella myosotis, and we analyze them together with another ten complete mitochondrial genomes of gastropods currently available in molecular databases in order to reconstruct the phylogenetic relationships among the main lineages of gastropods. Results Comparative analyses with other mollusk mitochondrial genomes allowed us to describe molecular features and general trends in the evolution of mitochondrial genome organization in gastropods. Phylogenetic reconstruction with commonly used methods of phylogenetic inference (ME, MP, ML, BI arrived at a single topology, which was used to reconstruct the evolution of mitochondrial gene rearrangements in the group. Conclusion Four main lineages were identified within gastropods: Caenogastropoda, Vetigastropoda, Patellogastropoda, and Heterobranchia. Caenogastropoda and Vetigastropoda are sister taxa, as well as, Patellogastropoda and Heterobranchia. This result rejects the validity of the derived clade Apogastropoda (Caenogastropoda + Heterobranchia. The position of Patellogastropoda remains unclear likely due to long-branch attraction biases. Within Heterobranchia, the most heterogeneous group of gastropods, neither Euthyneura (because of the inclusion of P

Targeted Transgenic Overexpression of Mitochondrial Thymidine Kinase (TK2) Alters Mitochondrial DNA (mtDNA) and Mitochondrial Polypeptide Abundance

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Hosseini, Seyed H.; Kohler, James J.; Haase, Chad P.; Tioleco, Nina; Stuart, Tami; Keebaugh, Erin; Ludaway, Tomika; Russ, Rodney; Green, Elgin; Long, Robert; Wang, Liya; Eriksson, Staffan; Lewis, William

2007-01-01

Mitochondrial toxicity limits nucleoside reverse transcriptase inhibitors (NRTIs) for acquired immune deficiency syndrome. NRTI triphosphates, the active moieties, inhibit human immunodeficiency virus reverse transcriptase and eukaryotic mitochondrial DNA polymerase pol-γ. NRTI phosphorylation seems to correlate with mitochondrial toxicity, but experimental evidence is lacking. Transgenic mice (TGs) with cardiac overexpression of thymidine kinase isoforms (mitochondrial TK2 and cytoplasmic TK1) were used to study NRTI mitochondrial toxicity. Echocardiography and nuclear magnetic resonance imaging defined cardiac performance and structure. TK gene copy and enzyme activity, mitochondrial (mt) DNA and polypeptide abundance, succinate dehydrogenase and cytochrome oxidase histochemistry, and electron microscopy correlated with transgenesis, mitochondrial structure, and biogenesis. Antiretroviral combinations simulated therapy. Untreated hTK1 or TK2 TGs exhibited normal left ventricle mass. In TK2 TGs, cardiac TK2 gene copy doubled, activity increased 300-fold, and mtDNA abundance doubled. Abundance of the 17-kd subunit of complex I, succinate dehydrogenase histochemical activity, and cristae density increased. NRTIs increased left ventricle mass 20% in TK2 TGs. TK activity increased 3 logs in hTK1 TGs, but no cardiac phenotype resulted. NRTIs abrogated functional effects of transgenically increased TK2 activity but had no effect on TK2 mtDNA abundance. Thus, NRTI mitochondrial phosphorylation by TK2 is integral to clinical NRTI mitochondrial toxicity. PMID:17322372

Molecular Regulation of the Mitochondrial F1Fo-ATPsynthase: Physiological and Pathological Significance of the Inhibitory Factor 1 (IF 1

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Danilo Faccenda

2012-01-01

Full Text Available In mammals, the mitochondrial F1Fo-ATPsynthase sets out the energy homeostasis by producing the bulk of cellular ATP. As for every enzyme, the laws of thermodynamics command it; however, it is privileged to have a dedicated molecular regulator that controls its rotation. This is the so-called ATPase Inhibitory Factor 1 (IF1 that blocks its reversal to avoid the consumption of cellular ATP when the enzyme acts as an ATP hydrolase. Recent evidence has also demonstrated that IF1 may control the alignment of the enzyme along the mitochondrial inner membrane, thus increasing the interest for the molecule. We conceived this review to outline the fundamental knowledge of the F1Fo-ATPsynthase and link it to the molecular mechanisms by which IF1 regulates its way of function, with the ultimate goal to highlight this as an important and possibly unique means to control this indispensable enzyme in both physiological and pathological settings.

The human SLC25A33 and SLC25A36 genes of solute carrier family 25 encode two mitochondrial pyrimidine nucleotide transporters.

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Di Noia, Maria Antonietta; Todisco, Simona; Cirigliano, Angela; Rinaldi, Teresa; Agrimi, Gennaro; Iacobazzi, Vito; Palmieri, Ferdinando

2014-11-28

The human genome encodes 53 members of the solute carrier family 25 (SLC25), also called the mitochondrial carrier family, many of which have been shown to transport inorganic anions, amino acids, carboxylates, nucleotides, and coenzymes across the inner mitochondrial membrane, thereby connecting cytosolic and matrix functions. Here two members of this family, SLC25A33 and SLC25A36, have been thoroughly characterized biochemically. These proteins were overexpressed in bacteria and reconstituted in phospholipid vesicles. Their transport properties and kinetic parameters demonstrate that SLC25A33 transports uracil, thymine, and cytosine (deoxy)nucleoside di- and triphosphates by an antiport mechanism and SLC25A36 cytosine and uracil (deoxy)nucleoside mono-, di-, and triphosphates by uniport and antiport. Both carriers also transported guanine but not adenine (deoxy)nucleotides. Transport catalyzed by both carriers was saturable and inhibited by mercurial compounds and other inhibitors of mitochondrial carriers to various degrees. In confirmation of their identity (i) SLC25A33 and SLC25A36 were found to be targeted to mitochondria and (ii) the phenotypes of Saccharomyces cerevisiae cells lacking RIM2, the gene encoding the well characterized yeast mitochondrial pyrimidine nucleotide carrier, were overcome by expressing SLC25A33 or SLC25A36 in these cells. The main physiological role of SLC25A33 and SLC25A36 is to import/export pyrimidine nucleotides into and from mitochondria, i.e. to accomplish transport steps essential for mitochondrial DNA and RNA synthesis and breakdown. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

Loss of Mitochondrial Function Impairs Lysosomes.

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Demers-Lamarche, Julie; Guillebaud, Gérald; Tlili, Mouna; Todkar, Kiran; Bélanger, Noémie; Grondin, Martine; Nguyen, Angela P; Michel, Jennifer; Germain, Marc

2016-05-06

Alterations in mitochondrial function, as observed in neurodegenerative diseases, lead to disrupted energy metabolism and production of damaging reactive oxygen species. Here, we demonstrate that mitochondrial dysfunction also disrupts the structure and function of lysosomes, the main degradation and recycling organelle. Specifically, inhibition of mitochondrial function, following deletion of the mitochondrial protein AIF, OPA1, or PINK1, as well as chemical inhibition of the electron transport chain, impaired lysosomal activity and caused the appearance of large lysosomal vacuoles. Importantly, our results show that lysosomal impairment is dependent on reactive oxygen species. Given that alterations in both mitochondrial function and lysosomal activity are key features of neurodegenerative diseases, this work provides important insights into the etiology of neurodegenerative diseases. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

Biguanide-induced mitochondrial dysfunction yields increased lactate production and cytotoxicity of aerobically-poised HepG2 cells and human hepatocytes in vitro

International Nuclear Information System (INIS)

Dykens, James A.; Jamieson, Joseph; Marroquin, Lisa; Nadanaciva, Sashi; Billis, Puja A.; Will, Yvonne

2008-01-01

As a class, the biguanides induce lactic acidosis, a hallmark of mitochondrial impairment. To assess potential mitochondrial impairment, we evaluated the effects of metformin, buformin and phenformin on: 1) viability of HepG2 cells grown in galactose, 2) respiration by isolated mitochondria, 3) metabolic poise of HepG2 and primary human hepatocytes, 4) activities of immunocaptured respiratory complexes, and 5) mitochondrial membrane potential and redox status in primary human hepatocytes. Phenformin was the most cytotoxic of the three with buformin showing moderate toxicity, and metformin toxicity only at mM concentrations. Importantly, HepG2 cells grown in galactose are markedly more susceptible to biguanide toxicity compared to cells grown in glucose, indicating mitochondrial toxicity as a primary mode of action. The same rank order of potency was observed for isolated mitochondrial respiration where preincubation (40 min) exacerbated respiratory impairment, and was required to reveal inhibition by metformin, suggesting intramitochondrial bio-accumulation. Metabolic profiling of intact cells corroborated respiratory inhibition, but also revealed compensatory increases in lactate production from accelerated glycolysis. High (mM) concentrations of the drugs were needed to inhibit immunocaptured respiratory complexes, supporting the contention that bioaccumulation is involved. The same rank order was found when monitoring mitochondrial membrane potential, ROS production, and glutathione levels in primary human hepatocytes. In toto, these data indicate that biguanide-induced lactic acidosis can be attributed to acceleration of glycolysis in response to mitochondrial impairment. Indeed, the desired clinical outcome, viz., decreased blood glucose, could be due to increased glucose uptake and glycolytic flux in response to drug-induced mitochondrial dysfunction

Fluorescent in situ hybridization of mitochondrial DNA and RNA

Czech Academy of Sciences Publication Activity Database

Alán, Lukáš; Zelenka, Jaroslav; Ježek, Jan; Dlasková, Andrea; Ježek, Petr

2010-01-01

Roč. 57, č. 4 (2010), s. 403-408 ISSN 0001-527X R&D Projects: GA ČR GAP302/10/0346; GA ČR GPP304/10/P204; GA AV ČR KJB500110902 Institutional research plan: CEZ:AV0Z50110509 Keywords : mitochondrial DNA and RNA * nucleoids of mitochondrial DNA * molecular beacon fluorescent hybridization probes Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 1.234, year: 2010

Co-ordinate decrease in the expression of the mitochondrial genome and nuclear genes for mitochondrial proteins in the lactation-induced mitochondrial hypotrophy of rat brown fat.

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Martin, I; Giralt, M; Viñas, O; Iglesias, R; Mampel, T; Villarroya, F

1995-01-01

The relative abundance of the mitochondrial-encoded mRNAs for cytochrome c oxidase subunit II and NADH dehydrogenase subunit I was lower in brown adipose tissue (BAT) from lactating rats than in virgin controls. This decrease was in parallel with a significant decrease in mitochondrial 16 S rRNA levels and in the relative content of mitochondrial DNA in the tissue. BAT from lactating rats showed lowered mRNA expression of the nuclear-encoded genes for the mitochondrial uncoupling protein, subunit IV of cytochrome c oxidase and the adenine nucleotide translocase isoforms ANT1 and ANT2, whereas mRNA levels for the ATP synthase beta-subunit were unchanged. However, the relative content of this last protein was lower in BAT mitochondria from lactating rats than in virgin controls. It is concluded that lactation-induced mitochondrial hypotrophy in BAT is associated with a co-ordinate decrease in the expression of the mitochondrial genome and nuclear genes for mitochondrial proteins. This decrease is caused by regulatory events acting at different levels, including pre- and post-transcriptional regulation. BAT appears to be a useful model with which to investigate the molecular mechanisms involved in the co-ordination of the expression of the mitochondrial and nuclear genomes during mitochondrial biogenesis. Images Figure 1 Figure 2 PMID:8948428

Molecular and Morphological Characterizations of Echinococcus granulosus from Human and Animal Isolates in Kashan, Markazi Province, Iran

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ARBABI, Mohsen; PIRESTANI, Majid; DELAVARI, Mahdi; HOOSHYAR, Hossein; ABDOLI, Amir; SARVI, Shahab

2017-01-01

Background: One of the most important zoonotic helminths in the world is known as Echinococcus granulosus. Different strains of the E. granulosus have been described based on morphological and molecular characterizations, however, there is limited information regarding the characteristics of the phenotypes and genotypes of E. granulosus in Iran. Methods: The present study was prepared to evaluate the phenotypic and genotypic diversity of E. granulosus isolates collected from human, goat, sheep, and cattle based on 19 standard morphometric parameters and mitochondrial and nuclear genes (CO1, ND1, and ITS1) in Kashan, Markazi Province, Iran during 2013–2014. Results: The biometric analysis for the 19 characters revealed that the 19 morphometric values of cattle isolates were exceptionally higher than human, goat, and sheep isolates (Pgranulosus travels between humans and other intermediate hosts of this parasite in the area study. PMID:28761477

Mitochondrial dysfunction in type 2 diabetes and obesity

DEFF Research Database (Denmark)

Højlund, Kurt; Mogensen, Martin; Sahlin, Kent

2008-01-01

for mitochondrial dysfunction in skeletal muscle of type 2 diabetic and prediabetic subjects, primarily due to a lower content of mitochondria (mitochondrial biogenesis) and possibly to a reduced functional capacity per mitochondrion. This article discusses the latest advances in the understanding of the molecular...

High Glucose-Induced Oxidative Stress Increases the Copy Number of Mitochondrial DNA in Human Mesangial Cells

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Ghada Al-Kafaji

2013-01-01

Full Text Available Oxidative damage to mitochondrial DNA (mtDNA has been linked to the pathogenicity of diabetic nephropathy. We tested the hypothesis that mtDNA copy number may be increased in human mesangial cells in response to high glucose-induced reactive oxygen species (ROS to compensate for damaged mtDNA. The effect of manganese superoxide dismutase mimetic (MnTBAP on glucose-induced mtDNA copy number was also examined. The copy number of mtDNA was determined by real-time PCR in human mesangial cells cultured in 5 mM glucose, 25 mM glucose, and mannitol (osmotic control, as well as in cells cultured in 25 mM glucose in the presence and absence of 200 μM MnTBAP. Intracellular ROS was assessed by confocal microscopy and flow cytometry in human mesangial cells. The copy number of mtDNA was significantly increased when human mesangial cells were incubated with 25 mM glucose compared to 5 mM glucose and mannitol. In addition, 25 mM glucose rapidly generated ROS in the cells, which was not detected in 5 mM glucose. Furthermore, mtDNA copy number was significantly decreased and maintained to normal following treatment of cells with 25 mM glucose and MnTBAP compared to 25 mM glucose alone. Inclusion of MnTBAP during 25 mM glucose incubation inhibited mitochondrial superoxide in human mesangial cells. Increased mtDNA copy number in human mesangial cells by high glucose could contribute to increased mitochondrial superoxide, and prevention of mtDNA copy number could have potential in retarding the development of diabetic nephropathy.

Identification of a mitochondrial target of thiazolidinedione insulin sensitizers (mTOT--relationship to newly identified mitochondrial pyruvate carrier proteins.

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Jerry R Colca

Full Text Available Thiazolidinedione (TZD insulin sensitizers have the potential to effectively treat a number of human diseases, however the currently available agents have dose-limiting side effects that are mediated via activation of the transcription factor PPARγ. We have recently shown PPARγ-independent actions of TZD insulin sensitizers, but the molecular target of these molecules remained to be identified. Here we use a photo-catalyzable drug analog probe and mass spectrometry-based proteomics to identify a previously uncharacterized mitochondrial complex that specifically recognizes TZDs. These studies identify two well-conserved proteins previously known as brain protein 44 (BRP44 and BRP44 Like (BRP44L, which recently have been renamed Mpc2 and Mpc1 to signify their function as a mitochondrial pyruvate carrier complex. Knockdown of Mpc1 or Mpc2 in Drosophila melanogaster or pre-incubation with UK5099, an inhibitor of pyruvate transport, blocks the crosslinking of mitochondrial membranes by the TZD probe. Knockdown of these proteins in Drosophila also led to increased hemolymph glucose and blocked drug action. In isolated brown adipose tissue (BAT cells, MSDC-0602, a PPARγ-sparing TZD, altered the incorporation of (13C-labeled carbon from glucose into acetyl CoA. These results identify Mpc1 and Mpc2 as components of the mitochondrial target of TZDs (mTOT and suggest that understanding the modulation of this complex, which appears to regulate pyruvate entry into the mitochondria, may provide a viable target for insulin sensitizing pharmacology.

Mitochondrial nucleoid clusters protect newly synthesized mtDNA during Doxorubicin- and Ethidium Bromide-induced mitochondrial stress

Czech Academy of Sciences Publication Activity Database

Alán, Lukáš; Špaček, Tomáš; Pajuelo-Reguera, David; Jabůrek, Martin; Ježek, Petr

2016-01-01

Roč. 302, Jul 1 (2016), s. 31-40 ISSN 0041-008X R&D Projects: GA ČR(CZ) GAP305/12/1247; GA MŠk(CZ) LQ1604; GA MŠk(CZ) ED1.1.00/02.0109 Institutional support: RVO:67985823 Keywords : Doxorubicin * Ethidium Bromide * nucleoid clusters * mitochondrial DNA stress * mitochondrial transcription factor A Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 3.791, year: 2016

Molecular epidemiology of ascariasis

DEFF Research Database (Denmark)

Betson, Martha; Halstead, Fennella; Nejsum, Peter

  We are using molecular epidemiology techniques to study the population structure of Ascaris obtained from humans and pigs. Worms were obtained from human hosts on Zanzibar and in Uganda, Bangladesh, Guatemala and Nepal and Ascaris from pigs were collected from in Uganda, Tanzania, Denmark......, Guatemala and the Philippines. Genomic DNA was extracted from each worm and a 450 base pair fragment of the mitochondrial cytochrome oxidase gene subunit 1 (COI) was PCR amplified. The products were sequenced from both strands and sequences were manually edited. Fifty different Ascaris CO1 haplotypes were...

Mitochondrial dynamics in type 2 diabetes: Pathophysiological implications

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Susana Rovira-Llopis

2017-04-01

Full Text Available Mitochondria play a key role in maintaining cellular metabolic homeostasis. These organelles have a high plasticity and are involved in dynamic processes such as mitochondrial fusion and fission, mitophagy and mitochondrial biogenesis. Type 2 diabetes is characterised by mitochondrial dysfunction, high production of reactive oxygen species (ROS and low levels of ATP. Mitochondrial fusion is modulated by different proteins, including mitofusin-1 (MFN1, mitofusin-2 (MFN2 and optic atrophy (OPA-1, while fission is controlled by mitochondrial fission 1 (FIS1, dynamin-related protein 1 (DRP1 and mitochondrial fission factor (MFF. PARKIN and (PTEN-induced putative kinase 1 (PINK1 participate in the process of mitophagy, for which mitochondrial fission is necessary. In this review, we discuss the molecular pathways of mitochondrial dynamics, their impairment under type 2 diabetes, and pharmaceutical approaches for targeting mitochondrial dynamics, such as mitochondrial division inhibitor-1 (mdivi-1, dynasore, P110 and 15-oxospiramilactone. Furthermore, we discuss the pathophysiological implications of impaired mitochondrial dynamics, especially in type 2 diabetes.

Peritoneal cavity lavage reduces the presence of mitochondrial damage associated molecular patterns in open abdomen patients.

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Martinez-Quinones, Patricia A; McCarthy, Cameron G; Mentzer, Caleb J; Wenceslau, Camilla F; Holsten, Steven B; Webb, R Clinton; O'Malley, Keith

2017-12-01

Mitochondrial damage-associated molecular patterns (mtDAMPs), such as mitochondrial DNA and N-formylated peptides, are endogenous molecules released from tissue after traumatic injury. mtDAMPs are potent activators of the innate immune system. They have similarities with bacteria, which allow mtDAMPs to interact with the same pattern recognition receptors and mediate the development of systemic inflammatory response syndrome (SIRS). Current recommendations for management of an open abdomen include returning to the operating room every 48 hours for peritoneal cavity lavage until definitive procedure. These patients are often critically ill and develop SIRS. We hypothesized that mitochondrial DAMPs are present in the peritoneal cavity fluid in this setting, and that they accumulate in the interval between washouts. We conducted a prospective pilot study of critically ill adult patients undergoing open abdomen management in the surgical and trauma intensive care units. Peritoneal fluid was collected daily from 10 open abdomen patients. Specimens were analyzed via quantitative polymerase chain reaction (qPCR) for mitochondrial DNA (mtDNA), via enzyme immunoassay for DNAse activity and via Western blot analysis for the ND6 subunit of the NADH: ubiquinone oxidoreductase, an N-formylated peptide. We observed a reduction in the expression of ND6 the day after lavage of the peritoneal cavity, that was statistically different from the days with no lavage (% change in ND6 expression, postoperative from washout: -50 ± 11 vs. no washout day, 42 ± 9; p abdomen. It is possible that increased frequency of peritoneal cavity lavage may lead to decreased systemic absorption of mtDAMPs, thereby reducing the risk of SIRS. Prospective study, Case Series, Level V.

Mitochondrial tRNA gene translocations in highly eusocial bees

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Daniela Silvestre

2006-01-01

Full Text Available Mitochondrial gene rearrangement events, especially involving tRNA genes, have been described more frequently as more complete mitochondrial genome sequences are becoming available. In the present work, we analyzed mitochondrial tRNA gene rearrangements between two bee species belonging to the tribes Apini and Meliponini within the "corbiculate Apidae". Eleven tRNA genes are in different genome positions or strands. The molecular events responsible for each translocation are explained. Considering the high number of rearrangements observed, the data presented here contradict the general rule of high gene order conservation among closely related organisms, and also represent a powerful molecular tool to help solve questions about phylogeny and evolution in bees.

Transcription profiles of mitochondrial genes correlate with mitochondrial DNA haplotypes in a natural population of Silene vulgaris

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Olson Matthew S

2010-01-01

Full Text Available Abstract Background Although rapid changes in copy number and gene order are common within plant mitochondrial genomes, associated patterns of gene transcription are underinvestigated. Previous studies have shown that the gynodioecious plant species Silene vulgaris exhibits high mitochondrial diversity and occasional paternal inheritance of mitochondrial markers. Here we address whether variation in DNA molecular markers is correlated with variation in transcription of mitochondrial genes in S. vulgaris collected from natural populations. Results We analyzed RFLP variation in two mitochondrial genes, cox1 and atp1, in offspring of ten plants from a natural population of S. vulgaris in Central Europe. We also investigated transcription profiles of the atp1 and cox1 genes. Most DNA haplotypes and transcription profiles were maternally inherited; for these, transcription profiles were associated with specific mitochondrial DNA haplotypes. One individual exhibited a pattern consistent with paternal inheritance of mitochondrial DNA; this individual exhibited a transcription profile suggestive of paternal but inconsistent with maternal inheritance. We found no associations between gender and transcript profiles. Conclusions Specific transcription profiles of mitochondrial genes were associated with specific mitochondrial DNA haplotypes in a natural population of a gynodioecious species S. vulgaris. Our findings suggest the potential for a causal association between rearrangements in the plant mt genome and transcription product variation.

Mitochondrial and bioenergetic dysfunction in human hepatic cells infected with dengue 2 virus

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El-Bacha , Tatiana; Midlej , Victor; Silva , Ana Paula Pereira Da; Costa , Leandro Silva Da; Benchimol , Marlene; Galina , Antonio; Poian , Andrea T. Da

2007-01-01

Mitochondrial and bioenergetic dysfunction in human hepatic cells infected with dengue 2 virus correspondence: Corresponding author. Fax: +55 21 22708647. (El-Bacha, Tatiana) (El-Bacha, Tatiana) Laboratorio de Bioquimica de Virus, Instituto de Bioquimica Medica, Universidade Federal do Rio de Janeiro - RJ-Brasil--> , Av. Bauhinia n? 400 ? CCS Bloco H 2? andar--> , sala 22. Ilha do Governador--> ...

Human, donkey and cow milk differently affects energy efficiency and inflammatory state by modulating mitochondrial function and gut microbiota.

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Trinchese, Giovanna; Cavaliere, Gina; Canani, Roberto Berni; Matamoros, Sebastien; Bergamo, Paolo; De Filippo, Chiara; Aceto, Serena; Gaita, Marcello; Cerino, Pellegrino; Negri, Rossella; Greco, Luigi; Cani, Patrice D; Mollica, Maria Pina

2015-11-01

Different nutritional components are able, by modulating mitochondrial function and gut microbiota composition, to influence body composition, metabolic homeostasis and inflammatory state. In this study, we aimed to evaluate the effects produced by the supplementation of different milks on energy balance, inflammatory state, oxidative stress and antioxidant/detoxifying enzyme activities and to investigate the role of the mitochondrial efficiency and the gut microbiota in the regulation of metabolic functions in an animal model. We compared the intake of human milk, gold standard for infant nutrition, with equicaloric supplementation of donkey milk, the best substitute for newborns due to its nutritional properties, and cow milk, the primary marketed product. The results showed a hypolipidemic effect produced by donkey and human milk intake in parallel with enhanced mitochondrial activity/proton leakage. Reduced mitochondrial energy efficiency and proinflammatory signals (tumor necrosis factor α, interleukin-1 and lipopolysaccharide levels) were associated with a significant increase of antioxidants (total thiols) and detoxifying enzyme activities (glutathione-S-transferase, NADH quinone oxidoreductase) in donkey- and human milk-treated animals. The beneficial effects were attributable, at least in part, to the activation of the nuclear factor erythroid-2-related factor-2 pathway. Moreover, the metabolic benefits induced by human and donkey milk may be related to the modulation of gut microbiota. In fact, milk treatments uniquely affected the proportions of bacterial phyla and genera, and we hypothesized that the increased concentration of fecal butyrate in human and donkey milk-treated rats was related to the improved lipid and glucose metabolism and detoxifying activities. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

Mitochondrial Dysfunction in Gliomas

Czech Academy of Sciences Publication Activity Database

Katsetos, C.D.; Anni, H.; Dráber, Pavel

2013-01-01

Roč. 20, č. 3 (2013), s. 216-227 ISSN 1071-9091 R&D Projects: GA MŠk LH12050 Institutional support: RVO:68378050 Keywords : gliomas * mitochondrial dysfunction * microtubule proteins Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 1.883, year: 2013

Cilostazol promotes mitochondrial biogenesis in human umbilical vein endothelial cells through activating the expression of PGC-1α

International Nuclear Information System (INIS)

Zuo, Luning; Li, Qiang; Sun, Bei; Xu, Zhiying; Ge, Zhiming

2013-01-01

Highlights: ► First time to show that cilostazol promotes the expressions of PGC-1α. ► First time to show that cilostazol stimulates mitochondrial biogenesis in HUVECs. ► PKA/CREB pathway mediates the effect of cilostazol on PGC-1α expression. ► Suggesting the roles of cilostazol in mitochondrial dysfunction related disease. -- Abstract: Mitochondrial dysfunction is frequently observed in vascular diseases. Cilostazol is a drug approved by the US Food and Drug Administration for the treatment of intermittent claudication. Cilostazol increases intracellular cyclic adenosine monophosphate (cAMP) levels through inhibition of type III phosphodiesterase. The effects of cilostazol in mitochondrial biogenesis in human umbilical vein endothelial cells (HUVECs) were investigated in this study. Cilostazol treated HUVECs displayed increased levels of ATP, mitochondrial DNA/nuclear DNA ratio, expressions of cytochrome B, and mitochondrial mass, suggesting an enhanced mitochondrial biogenesis induced by cilostazol. The promoted mitochondrial biogenesis could be abolished by Protein kinase A (PKA) specific inhibitor H-89, implying that PKA pathway played a critical role in increased mitochondrial biogenesis after cilostazol treatment. Indeed, expression levels of peroxisome proliferator activator receptor gamma-coactivator 1α (PGC-1α), NRF 1 and mitochondrial transcription factor A (TFAM) were significantly increased in HUVECs after incubation with cilostazol at both mRNA levels and protein levels. Importantly, knockdown of PGC-1α could abolish cilostazol-induced mitochondrial biogenesis. Enhanced expression of p-CREB and PGC-1α induced by cilostazol could be inhibited by H-89. Moreover, the increased expression of PGC-1α induced by cilostazol could be inhibited by downregulation of CREB using CREB siRNA at both mRNA and protein levels. All the results indicated that cilostazol promoted mitochondrial biogenesis through activating the expression of PGC-1α in

Atypical mitochondrial inheritance patterns in eukaryotes.

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Breton, Sophie; Stewart, Donald T

2015-10-01

Mitochondrial DNA (mtDNA) is predominantly maternally inherited in eukaryotes. Diverse molecular mechanisms underlying the phenomenon of strict maternal inheritance (SMI) of mtDNA have been described, but the evolutionary forces responsible for its predominance in eukaryotes remain to be elucidated. Exceptions to SMI have been reported in diverse eukaryotic taxa, leading to the prediction that several distinct molecular mechanisms controlling mtDNA transmission are present among the eukaryotes. We propose that these mechanisms will be better understood by studying the deviations from the predominating pattern of SMI. This minireview summarizes studies on eukaryote species with unusual or rare mitochondrial inheritance patterns, i.e., other than the predominant SMI pattern, such as maternal inheritance of stable heteroplasmy, paternal leakage of mtDNA, biparental and strictly paternal inheritance, and doubly uniparental inheritance of mtDNA. The potential genes and mechanisms involved in controlling mitochondrial inheritance in these organisms are discussed. The linkage between mitochondrial inheritance and sex determination is also discussed, given that the atypical systems of mtDNA inheritance examined in this minireview are frequently found in organisms with uncommon sexual systems such as gynodioecy, monoecy, or andromonoecy. The potential of deviations from SMI for facilitating a better understanding of a number of fundamental questions in biology, such as the evolution of mtDNA inheritance, the coevolution of nuclear and mitochondrial genomes, and, perhaps, the role of mitochondria in sex determination, is considerable.

The Role of Therapeutic Drugs on Acquired Mitochondrial Toxicity.

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Morén, Constanza; Juárez-Flores, Diana Luz; Cardellach, Francesc; Garrabou, Glòria

2016-01-01

Certain therapeutic drugs used in medical practice may trigger mitochondrial toxicity leading to a wide range of clinical symptoms including deafness, neuropathy, myopathy, hyperlactatemia, lactic acidosis, pancreatitis and lipodystrophy, among others, which could even compromise the life of the patient. The aim of this work is to review the potential mitochondrial toxicity derived from drugs used in health care, including anesthetics, antiepileptics, neuroleptics, antidepressants, antivirals, antibiotics, antifungals, antimalarics, antineoplastics, antidiabetics, hypolipemiants, antiarrhythmics, anti-inflammatories and nitric oxide. We herein have reviewed data from experimental and clinical studies to document the molecular mitochondrial basis, potential biomarkers and putative clinical symptoms associated to secondary effects of drugs. One hundred and forty-five articles were selected and the information was organized by means of the primary target to which pharmacologic drugs were directed. Adverse toxic events were classified depending on the mitochondrial offtarget effect and whether they had been demonstrated in the experimental or clinical setting. Since treatment of acquired mitochondriopathies remains supportive and therapeutic interventions cannot be avoided, information of molecular and clinical consequences of toxic exposure becomes fundamental to assess riskbenefit imbalance of treatment prescription. Additionally, there is a crucial need to develop less mitochondrial toxic compounds, novel biomarkers to follow up mitochondrial toxicity (or implement those already proposed) and new approaches to prevent or revert unintended mitochondrial damage.

Bezafibrate induces a mitochondrial derangement in human cell lines: a PPAR-independent mechanism for a peroxisome proliferator.

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Scatena, R; Bottoni, P; Vincenzoni, F; Messana, I; Martorana, G E; Nocca, G; De Sole, P; Maggiano, N; Castagnola, M; Giardina, B

2003-11-01

Bezafibrate is a hypolipidemic drug that belongs to the group of peroxisome proliferators because it binds to peroxisome proliferator-activated receptors type alpha (PPARs). Peroxisome proliferators produce a myriad of extraperoxisomal effects, which are not necessarily dependent on their interaction with PPARs. An investigation on the peculiar activities of bezafibrate could clarify some of the molecular events and the relationship with the biochemical and pharmacological properties of this class of compounds. In this view, the human acute promyelocytic leukemia HL-60 cell line and human rabdomiosarcoma TE-671 cell line were cultured in media containing bezafibrate and a number of observations such as spectrophotometric analysis of mitochondrial respiratory chain enzymes, NMR metabolite determinations, phosphofructokinase enzymatic analysis, and differentiation assays were carried on. Bezafibrate induced a derangement of NADH cytochrome c reductase activity accompanied by metabolic alterations, mainly a shift to anaerobic glycolysis and an increase of fatty acid oxidation, as shown by NMR analysis of culture supernatants where acetate, lactate, and alanine levels increased. On the whole, the present results suggest a biochemical profile and a therapeutic role of this class of PPARs ligands more complex than those previously proposed.

Mutations in valosin-containing protein (VCP) decrease ADP/ATP translocation across the mitochondrial membrane and impair energy metabolism in human neurons.

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Ludtmann, Marthe H R; Arber, Charles; Bartolome, Fernando; de Vicente, Macarena; Preza, Elisavet; Carro, Eva; Houlden, Henry; Gandhi, Sonia; Wray, Selina; Abramov, Andrey Y

2017-05-26

Mutations in the gene encoding valosin-containing protein (VCP) lead to multisystem proteinopathies including frontotemporal dementia. We have previously shown that patient-derived VCP mutant fibroblasts exhibit lower mitochondrial membrane potential, uncoupled respiration, and reduced ATP levels. This study addresses the underlying basis for mitochondrial uncoupling using VCP knockdown neuroblastoma cell lines, induced pluripotent stem cells (iPSCs), and iPSC-derived cortical neurons from patients with pathogenic mutations in VCP Using fluorescent live cell imaging and respiration analysis we demonstrate a VCP mutation/knockdown-induced dysregulation in the adenine nucleotide translocase, which results in a slower rate of ADP or ATP translocation across the mitochondrial membranes. This deregulation can explain the mitochondrial uncoupling and lower ATP levels in VCP mutation-bearing neurons via reduced ADP availability for ATP synthesis. This study provides evidence for a role of adenine nucleotide translocase in the mechanism underlying altered mitochondrial function in VCP-related degeneration, and this new insight may inform efforts to better understand and manage neurodegenerative disease and other proteinopathies. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Mitochondrial Sirtuin 4 Resolves Immune Tolerance in Monocytes by Rebalancing Glycolysis and Glucose Oxidation Homeostasis

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Jie Tao

2018-03-01

Full Text Available The goal of this investigation was to define the molecular mechanism underlying physiologic conversion of immune tolerance to resolution of the acute inflammatory response, which is unknown. An example of this knowledge gap and its clinical importance is the broad-based energy deficit and immunometabolic paralysis in blood monocytes from non-survivors of human and mouse sepsis that precludes sepsis resolution. This immunometabolic dysregulation is biomarked by ex vivo endotoxin tolerance to increased glycolysis and TNF-α expression. To investigate how tolerance switches to resolution, we adapted our previously documented models associated with acute inflammatory, immune, and metabolic reprogramming that induces endotoxin tolerance as a model of sepsis in human monocytes. We report here that mitochondrial sirtuin 4 (SIRT4 physiologically breaks tolerance and resolves acute inflammation in human monocytes by coordinately reprogramming of metabolism and bioenergetics. We find that increased SIRT4 mRNA and protein expression during immune tolerance counters the increase in pyruvate dehydrogenase kinase 1 (PDK1 and SIRT1 that promote tolerance by switching glucose-dependent support of immune resistance to fatty acid oxidation support of immune tolerance. By decreasing PDK1, pyruvate dehydrogenase complex reactivation rebalances mitochondrial respiration, and by decreasing SIRT1, SIRT4 represses fatty acid oxidation. The precise mechanism for the mitochondrial SIRT4 nuclear feedback is unclear. Our findings are consistent with a new concept in which mitochondrial SIRT4 directs the axis that controls anabolic and catabolic energy sources.

Mutation of the human mitochondrial phenylalanine-tRNA synthetase causes infantile-onset epilepsy and cytochrome c oxidase deficiency.

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Almalki, Abdulraheem; Alston, Charlotte L; Parker, Alasdair; Simonic, Ingrid; Mehta, Sarju G; He, Langping; Reza, Mojgan; Oliveira, Jorge M A; Lightowlers, Robert N; McFarland, Robert; Taylor, Robert W; Chrzanowska-Lightowlers, Zofia M A

2014-01-01

Mitochondrial aminoacyl-tRNA synthetases (aaRSs) are essential enzymes in protein synthesis since they charge tRNAs with their cognate amino acids. Mutations in the genes encoding mitochondrial aaRSs have been associated with a wide spectrum of human mitochondrial diseases. Here we report the identification of pathogenic mutations (a partial genomic deletion and a highly conserved p. Asp325Tyr missense variant) in FARS2, the gene encoding mitochondrial phenylalanyl-tRNA synthetase, in a patient with early-onset epilepsy and isolated complex IV deficiency in muscle. The biochemical defect was expressed in myoblasts but not in fibroblasts and associated with decreased steady state levels of COXI and COXII protein and reduced steady state levels of the mt-tRNA(Phe) transcript. Functional analysis of the recombinant mutant p. Asp325Tyr FARS2 protein showed an inability to bind ATP and consequently undetectable aminoacylation activity using either bacterial tRNA or human mt-tRNA(Phe) as substrates. Lentiviral transduction of cells with wildtype FARS2 restored complex IV protein levels, confirming that the p.Asp325Tyr mutation is pathogenic, causing respiratory chain deficiency and neurological deficits on account of defective aminoacylation of mt-tRNA(Phe). © 2013. Published by Elsevier B.V. All rights reserved.

Mitochondrial damage and cytoskeleton reorganization in human dermal fibroblasts exposed to artificial visible light similar to screen-emitted light.

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Rascalou, Adeline; Lamartine, Jérôme; Poydenot, Pauline; Demarne, Frédéric; Bechetoille, Nicolas

2018-05-05

Artificial visible light is everywhere in modern life. Social communication confronts us with screens of all kinds, and their use is on the rise. We are therefore increasingly exposed to artificial visible light, the effects of which on skin are poorly known. The purpose of this study was to model the artificial visible light emitted by electronic devices and assess its effect on normal human fibroblasts. The spectral irradiance emitted by electronic devices was optically measured and equipment was developed to accurately reproduce such artificial visible light. Effects on normal human fibroblasts were analyzed on human genome microarray-based gene expression analysis. At cellular level, visualization and image analysis were performed on the mitochondrial network and F-actin cytoskeleton. Cell proliferation, ATP release and type I procollagen secretion were also measured. We developed a device consisting of 36 LEDs simultaneously emitting blue, green and red light at distinct wavelengths (450 nm, 525 nm and 625 nm) with narrow spectra and equivalent radiant power for the three colors. A dose of 99 J/cm 2 artificial visible light was selected so as not to induce cell mortality following exposure. Microarray analysis revealed 2984 light-modulated transcripts. Functional annotation of light-responsive genes revealed several enriched functions including, amongst others, the "mitochondria" and "integrin signaling" categories. Selected results were confirmed by real-time quantitative PCR, analyzing 24 genes representing these two categories. Analysis of micro-patterned culture plates showed marked fragmentation of the mitochondrial network and disorganization of the F-actin cytoskeleton following exposure. Functionally, there was considerable impairment of cell growth and spread, ATP release and type I procollagen secretion in exposed fibroblasts. Artificial visible light induces drastic molecular and cellular changes in normal human fibroblasts. This may impede

Modulation of mitochondrial morphology by bioenergetics defects in primary human fibroblasts

DEFF Research Database (Denmark)

Guillery, O.; Malka, F.; Frachon, P.

2008-01-01

induced partial but significant mitochondrial fragmentation, whereas dissipation of mitochondrial membrane potential (D Psi m) provoked complete fragmentation, and glycolysis inhibition had no effect. Oxidative phosphorylation defective fibroblasts had essentially normal filamentous mitochondria under...... basal conditions, although when challenged some of them presented with mild alteration of fission or fusion efficacy. Severely defective cells disclosed complete mitochondrial fragmentation under glycolysis inhibition. In conclusion, mitochondrial morphology is modulated by D Psi m but loosely linked...... to mitochondrial oxidative phosphorylation. Its alteration by glycolysis, inhibition points to a severe oxidative phosphorylation defect. (C) 2008 Elsevier B.V. All rights reserved Udgivelsesdato: 2008/4...

Unusual mitochondrial genome structures throughout the Euglenozoa

Czech Academy of Sciences Publication Activity Database

Roy, J.; Faktorová, Drahomíra; Lukeš, Julius; Burger, G.

2007-01-01

Roč. 158, č. 3 (2007), s. 385-396 ISSN 1434-4610 R&D Projects: GA ČR GA204/06/1558; GA MŠk 2B06129 Grant - others:Canadian Institutes of Health Research(CA) MOP-79309 Institutional research plan: CEZ:AV0Z60220518 Keywords : euglenozoan protists * mitochondrial chromosomes * mitochondrial ultrastructure Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 3.102, year: 2007

High-confidence assessment of functional impact of human mitochondrial non-synonymous genome variations by APOGEE.

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Stefano Castellana

2017-06-01

Full Text Available 24,189 are all the possible non-synonymous amino acid changes potentially affecting the human mitochondrial DNA. Only a tiny subset was functionally evaluated with certainty so far, while the pathogenicity of the vast majority was only assessed in-silico by software predictors. Since these tools proved to be rather incongruent, we have designed and implemented APOGEE, a machine-learning algorithm that outperforms all existing prediction methods in estimating the harmfulness of mitochondrial non-synonymous genome variations. We provide a detailed description of the underlying algorithm, of the selected and manually curated training and test sets of variants, as well as of its classification ability.

Disruption of mitochondrial DNA replication in Drosophila increases mitochondrial fast axonal transport in vivo.

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Rehan M Baqri

Full Text Available Mutations in mitochondrial DNA polymerase (pol gamma cause several progressive human diseases including Parkinson's disease, Alper's syndrome, and progressive external ophthalmoplegia. At the cellular level, disruption of pol gamma leads to depletion of mtDNA, disrupts the mitochondrial respiratory chain, and increases susceptibility to oxidative stress. Although recent studies have intensified focus on the role of mtDNA in neuronal diseases, the changes that take place in mitochondrial biogenesis and mitochondrial axonal transport when mtDNA replication is disrupted are unknown. Using high-speed confocal microscopy, electron microscopy and biochemical approaches, we report that mutations in pol gamma deplete mtDNA levels and lead to an increase in mitochondrial density in Drosophila proximal nerves and muscles, without a noticeable increase in mitochondrial fragmentation. Furthermore, there is a rise in flux of bidirectional mitochondrial axonal transport, albeit with slower kinesin-based anterograde transport. In contrast, flux of synaptic vesicle precursors was modestly decreased in pol gamma-alpha mutants. Our data indicate that disruption of mtDNA replication does not hinder mitochondrial biogenesis, increases mitochondrial axonal transport, and raises the question of whether high levels of circulating mtDNA-deficient mitochondria are beneficial or deleterious in mtDNA diseases.

Elevated mitochondrial gene expression during rat liver regeneration after portal vein ligation.

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Shimizu, Y; Suzuki, H; Nimura, Y; Onoue, S; Nagino, M; Tanaka, M; Ozawa, T

1995-10-01

We explored the molecular basis of mitochondrial energy production during rat liver regeneration after portal vein ligation. Ligation of the left branch of the portal vein induces an increase in the weight of the nonligated lobe, counterbalancing the reduced weight of the ligated lobe. Using this model, we investigated changes in mitochondrial DNA-binding proteins, mitochondrial DNA, and mitochondrial messenger RNA (mRNA) in rat hepatocytes of the nonligated lobes. The amount of mitochondrial DNA-binding protein increased maximally (200% to 300% of the preoperative level) at 12 hours after the operation, before an increase (390%) in mitochondrial DNA content at 24 hours, and parallel to an increase (240%) in mitochondrial mRNA levels at 12 hours. These results suggest that the energy supply for liver regeneration is achieved through enhancement of mitochondrial DNA replication as well as transcription, in which the mitochondrial DNA-binding proteins probably play regulatory roles. We also found that in the nonligated lobes, mRNA levels of hepatocyte growth factor increased to a detectable level only 12 hours after the operation. These molecular biochemical data help explain why preoperative portal vein embolization, which is a modification of portal vein branch ligation, is an effective method to prevent posthepatectomy liver failure.

Mitochondrial DNA: A Blind Spot in Neuroepigenetics.

Science.gov (United States)

Manev, Hari; Dzitoyeva, Svetlana; Chen, Hu

2012-04-01

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.

Restoration of Mitochondrial NAD+ Levels Delays Stem Cell Senescence and Facilitates Reprogramming of Aged Somatic Cells.

Science.gov (United States)

Son, Myung Jin; Kwon, Youjeong; Son, Taekwon; Cho, Yee Sook

2016-12-01

The fundamental tenet that aging is irreversible has been challenged by the development of reprogramming technology that can restore molecular and cellular age by reversing the progression of aging. The use of cells from aged individuals as sources for reprogramming or transplantation creates a major barrier in stem cell therapy with respect to cell quality and quantity. Here, we investigated the molecular features underlying senescence and rejuvenation during aged cell reprogramming and identified novel factors that can overcome age-associated barriers. Enzymes, such as nicotinamide nucleotide transhydrogenase (NNT) and nicotinamide mononucleotide adenylyltransferase 3 (NMNAT3), that control mitochondrial NAD + levels appear to be susceptible to aging. In aged cells, mitochondrial NAD + levels decrease, accompanied by reduced SIRT3 activity; these changes severely impede cell fate transition. However, in cells collected from aged p16 knockout mice, which exhibit delayed cellular senescence, no changes in NNT or NMNAT3 expression were found. Importantly, restoring mitochondrial NAD + levels by overexpressing NNT and NMNAT3 enhanced reprogramming efficiency of aged somatic cells and extended the lifespan of human mesenchymal stem cells by delaying replicative senescence. These results demonstrate that maintenance of mitochondrial NAD + levels is critical for reversing the mechanisms of aging and ensuring that cells collected from aged individuals are of high quality. Stem Cells 2016;34:2840-2851. © 2016 AlphaMed Press.

RECQL4 localizes to mitochondria and preserves mitochondrial DNA integrity

DEFF Research Database (Denmark)

Croteau, Deborah L; Rossi, Marie L; Canugovi, Chandrika

2012-01-01

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......Q helicase to be found in both human and mouse mitochondria, and the loss of RECQL4 alters mitochondrial integrity....

Mitochondrial damage and cholesterol storage in human hepatocellular carcinoma cells with silencing of UBIAD1 gene expression

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Carlos R. Morales

2014-01-01

Full Text Available Heterozygous mutations in the UBIAD1 gene cause Schnyder corneal dystrophy characterized by abnormal cholesterol and phospholipid deposits in the cornea. Ubiad1 protein was recently identified as Golgi prenyltransferase responsible for biosynthesis of vitamin K2 and CoQ10, a key protein in the mitochondrial electron transport chain. Our study shows that silencing UBIAD1 in cultured human hepatocellular carcinoma cells causes dramatic morphological changes and cholesterol storage in the mitochondria, emphasizing an important role of UBIAD1 in mitochondrial function.

Changes in mitochondrial respiration in the human placenta over gestation.

Science.gov (United States)

Holland, Olivia J; Hickey, Anthony J R; Alvsaker, Anna; Moran, Stephanie; Hedges, Christopher; Chamley, Lawrence W; Perkins, Anthony V

2017-09-01

Placental mitochondria are subjected to micro-environmental changes throughout gestation, in particular large variations in oxygen. How placental mitochondrial respiration adapts to changing oxygen concentrations remains unexplored. Additionally, placental tissue is often studied in culture; however, the effect of culture on placental mitochondria is unclear. Placental tissue was obtained from first trimester and term (laboured and non-laboured) pregnancies, and selectively permeabilized to access mitochondria. Respirometry was used to compare respiration states and substrate use in mitochondria. Additionally, explants of placental tissue were cultured for four, 12, 24, 48, or 96 h and respiration measured. Mitochondrial respiration decreased at 11 weeks compared to earlier gestations (p = 0.05-0.001), and mitochondrial content increased at 12-13 weeks compared to 7-10 weeks (p = 0.042). In term placentae, oxidative phosphorylation (OXPHOS) through mitochondrial complex IV (p Respiration was increased (p ≤ 0.006-0.001) in laboured compared to non-laboured placenta. After four hours of culture, respiration was depressed compared to fresh tissue from the same placenta and continued to decline with time in culture. Markers of apoptosis were increased, while markers of autophagy, mitochondrial biogenesis, and mitochondrial membrane potential were decreased after four hours of culture. Respiration and mitochondrial content alter over gestation/with labour. Decreased respiration at 11 weeks and increased mitochondrial content at 12-13 weeks may relate to onset of maternal blood flow, and increased respiration as a result of labour may be an adaptation to ischaemia-reperfusion. At term, mitochondria were more susceptible to changes in respiratory function relative to first trimester when cultured in vitro, perhaps reflecting changes in metabolic demands as gestation progresses. Metabolic plasticity of placental mitochondria has relevance to placenta

Mitochondrial Band-7 family proteins: scaffolds for respiratory chain assembly?

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Bernadette eGehl

2014-04-01

Full Text Available The band-7 protein family comprises a diverse set of membrane-bound proteins characterised by the presence of a conserved domain. The exact function of this band-7 domain remains elusive, but examples from animal and bacterial stomatin-type proteins demonstrate binding to lipids and the ability to assemble into membrane-bound oligomers that form putative scaffolds. Some members, such as prohibitins and human stomatin-like protein 2 (HsSLP2, localise to the mitochondrial inner membrane where they function in cristae formation and hyperfusion. In Arabidopsis, the band-7 protein family has diversified and includes plant-specific members. Mitochondrial-localised members include prohibitins (AtPHBs and two stomatin-like proteins (AtSLP1 and -2. Studies into PHB function in plants have demonstrated an involvement in root meristem proliferation and putative scaffold formation for mAAA proteases, but it remains unknown how these roles are achieved at the molecular level. In this minireview we summarise the current status of band-7 protein functions in Arabidopsis, and speculate how the mitochondrial members might recruit specific lipids to form microdomains that could shape the organisation and functioning of the respiratory chain.

Mitochondrially targeted anti-cancer agents

Czech Academy of Sciences Publication Activity Database

Biasutto, L.; Dong, L.A.; Zoratti, M.; Neužil, Jiří

2010-01-01

Roč. 10, č. 6 (2010), s. 670-681 ISSN 1567-7249 Institutional research plan: CEZ:AV0Z50520701 Keywords : Mitochondrial targeting * pro-oxidant effect * reactive oxygen species Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 3.238, year: 2010

Telmisartan enhances mitochondrial activity and alters cellular functions in human coronary artery endothelial cells via AMP-activated protein kinase pathway.

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Kurokawa, Hirofumi; Sugiyama, Seigo; Nozaki, Toshimitsu; Sugamura, Koichi; Toyama, Kensuke; Matsubara, Junichi; Fujisue, Koichiro; Ohba, Keisuke; Maeda, Hirofumi; Konishi, Masaaki; Akiyama, Eiichi; Sumida, Hitoshi; Izumiya, Yasuhiro; Yasuda, Osamu; Kim-Mitsuyama, Shokei; Ogawa, Hisao

2015-04-01

Mitochondrial dysfunction plays an important role in cellular senescence and impaired function of vascular endothelium, resulted in cardiovascular diseases. Telmisartan is a unique angiotensin II type I receptor blocker that has been shown to prevent cardiovascular events in high risk patients. AMP-activated protein kinase (AMPK) plays a critical role in mitochondrial biogenesis and endothelial function. This study assessed whether telmisartan enhances mitochondrial function and alters cellular functions via AMPK in human coronary artery endothelial cells (HCAECs). In cultured HCAECs, telmisartan significantly enhanced mitochondrial activity assessed by mitochondrial reductase activity and intracellular ATP production and increased the expression of mitochondria related genes. Telmisartan prevented cellular senescence and exhibited the anti-apoptotic and pro-angiogenic properties. The expression of genes related anti-oxidant and pro-angiogenic properties were increased by telmisartan. Telmisartan increased endothelial NO synthase and AMPK phosphorylation. Peroxisome proliferator-activated receptor gamma signaling was not involved in telmisartan-induced improvement of mitochondrial function. All of these effects were abolished by inhibition of AMPK. Telmisartan enhanced mitochondrial activity and exhibited anti-senescence effects and improving endothelial function through AMPK in HCAECs. Telmisartan could provide beneficial effects on vascular diseases via enhancement of mitochondrial activity and modulating endothelial function through AMPK activation. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Subcellular Distribution of NAD+ between Cytosol and Mitochondria Determines the Metabolic Profile of Human Cells.

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VanLinden, Magali R; Dölle, Christian; Pettersen, Ina K N; Kulikova, Veronika A; Niere, Marc; Agrimi, Gennaro; Dyrstad, Sissel E; Palmieri, Ferdinando; Nikiforov, Andrey A; Tronstad, Karl Johan; Ziegler, Mathias

2015-11-13

The mitochondrial NAD pool is particularly important for the maintenance of vital cellular functions. Although at least in some fungi and plants, mitochondrial NAD is imported from the cytosol by carrier proteins, in mammals, the mechanism of how this organellar pool is generated has remained obscure. A transporter mediating NAD import into mammalian mitochondria has not been identified. In contrast, human recombinant NMNAT3 localizes to the mitochondrial matrix and is able to catalyze NAD(+) biosynthesis in vitro. However, whether the endogenous NMNAT3 protein is functionally effective at generating NAD(+) in mitochondria of intact human cells still remains to be demonstrated. To modulate mitochondrial NAD(+) content, we have expressed plant and yeast mitochondrial NAD(+) carriers in human cells and observed a profound increase in mitochondrial NAD(+). None of the closest human homologs of these carriers had any detectable effect on mitochondrial NAD(+) content. Surprisingly, constitutive redistribution of NAD(+) from the cytosol to the mitochondria by stable expression of the Arabidopsis thaliana mitochondrial NAD(+) transporter NDT2 in HEK293 cells resulted in dramatic growth retardation and a metabolic shift from oxidative phosphorylation to glycolysis, despite the elevated mitochondrial NAD(+) levels. These results suggest that a mitochondrial NAD(+) transporter, similar to the known one from A. thaliana, is likely absent and could even be harmful in human cells. We provide further support for the alternative possibility, namely intramitochondrial NAD(+) synthesis, by demonstrating the presence of endogenous NMNAT3 in the mitochondria of human cells. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

A Molecular Phylogeny of Hemiptera Inferred from Mitochondrial Genome Sequences

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Song, Nan; Liang, Ai-Ping; Bu, Cui-Ping

2012-01-01

Classically, Hemiptera is comprised of two suborders: Homoptera and Heteroptera. Homoptera includes Cicadomorpha, Fulgoromorpha and Sternorrhyncha. However, according to previous molecular phylogenetic studies based on 18S rDNA, Fulgoromorpha has a closer relationship to Heteroptera than to other hemipterans, leaving Homoptera as paraphyletic. Therefore, the position of Fulgoromorpha is important for studying phylogenetic structure of Hemiptera. We inferred the evolutionary affiliations of twenty-five superfamilies of Hemiptera using mitochondrial protein-coding genes and rRNAs. We sequenced three mitogenomes, from Pyrops candelaria, Lycorma delicatula and Ricania marginalis, representing two additional families in Fulgoromorpha. Pyrops and Lycorma are representatives of an additional major family Fulgoridae in Fulgoromorpha, whereas Ricania is a second representative of the highly derived clade Ricaniidae. The organization and size of these mitogenomes are similar to those of the sequenced fulgoroid species. Our consensus phylogeny of Hemiptera largely supported the relationships (((Fulgoromorpha,Sternorrhyncha),Cicadomorpha),Heteroptera), and thus supported the classic phylogeny of Hemiptera. Selection of optimal evolutionary models (exclusion and inclusion of two rRNA genes or of third codon positions of protein-coding genes) demonstrated that rapidly evolving and saturated sites should be removed from the analyses. PMID:23144967

A molecular phylogeny of Hemiptera inferred from mitochondrial genome sequences.

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Nan Song

Full Text Available Classically, Hemiptera is comprised of two suborders: Homoptera and Heteroptera. Homoptera includes Cicadomorpha, Fulgoromorpha and Sternorrhyncha. However, according to previous molecular phylogenetic studies based on 18S rDNA, Fulgoromorpha has a closer relationship to Heteroptera than to other hemipterans, leaving Homoptera as paraphyletic. Therefore, the position of Fulgoromorpha is important for studying phylogenetic structure of Hemiptera. We inferred the evolutionary affiliations of twenty-five superfamilies of Hemiptera using mitochondrial protein-coding genes and rRNAs. We sequenced three mitogenomes, from Pyrops candelaria, Lycorma delicatula and Ricania marginalis, representing two additional families in Fulgoromorpha. Pyrops and Lycorma are representatives of an additional major family Fulgoridae in Fulgoromorpha, whereas Ricania is a second representative of the highly derived clade Ricaniidae. The organization and size of these mitogenomes are similar to those of the sequenced fulgoroid species. Our consensus phylogeny of Hemiptera largely supported the relationships (((Fulgoromorpha,Sternorrhyncha,Cicadomorpha,Heteroptera, and thus supported the classic phylogeny of Hemiptera. Selection of optimal evolutionary models (exclusion and inclusion of two rRNA genes or of third codon positions of protein-coding genes demonstrated that rapidly evolving and saturated sites should be removed from the analyses.

Mapping of Mitochondrial RNA-Protein Interactions by Digital RNase Footprinting

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Ganqiang Liu

2013-11-01

Full Text Available Human mitochondrial DNA is transcribed as long polycistronic transcripts that encompass each strand of the genome and are processed subsequently into mature mRNAs, tRNAs, and rRNAs, necessitating widespread posttranscriptional regulation. Here, we establish methods for massively parallel sequencing and analyses of RNase-accessible regions of human mitochondrial RNA and thereby identify specific regions within mitochondrial transcripts that are bound by proteins. This approach provides a range of insights into the contribution of RNA-binding proteins to the regulation of mitochondrial gene expression.

Mis-targeting of the mitochondrial protein LIPT2 leads to apoptotic cell death.

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Emanuele Bernardinelli

Full Text Available Lipoyl(Octanoyl Transferase 2 (LIPT2 is a protein involved in the post-translational modification of key energy metabolism enzymes in humans. Defects of lipoic acid synthesis and transfer start to emerge as causes of fatal or severe early-onset disease. We show that the first 31 amino acids of the N-terminus of LIPT2 represent a mitochondrial targeting sequence and inhibition of the transit of LIPT2 to the mitochondrion results in apoptotic cell death associated with activation of the apoptotic volume decrease (AVD current in normotonic conditions, as well as over-activation of the swelling-activated chloride current (IClswell, mitochondrial membrane potential collapse, caspase-3 cleavage and nuclear DNA fragmentation. The findings presented here may help elucidate the molecular mechanisms underlying derangements of lipoic acid biosynthesis.

Why barcode? High-throughput multiplex sequencing of mitochondrial genomes for molecular systematics.

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Timmermans, M J T N; Dodsworth, S; Culverwell, C L; Bocak, L; Ahrens, D; Littlewood, D T J; Pons, J; Vogler, A P

2010-11-01

Mitochondrial genome sequences are important markers for phylogenetics but taxon sampling remains sporadic because of the great effort and cost required to acquire full-length sequences. Here, we demonstrate a simple, cost-effective way to sequence the full complement of protein coding mitochondrial genes from pooled samples using the 454/Roche platform. Multiplexing was achieved without the need for expensive indexing tags ('barcodes'). The method was trialled with a set of long-range polymerase chain reaction (PCR) fragments from 30 species of Coleoptera (beetles) sequenced in a 1/16th sector of a sequencing plate. Long contigs were produced from the pooled sequences with sequencing depths ranging from ∼10 to 100× per contig. Species identity of individual contigs was established via three 'bait' sequences matching disparate parts of the mitochondrial genome obtained by conventional PCR and Sanger sequencing. This proved that assembly of contigs from the sequencing pool was correct. Our study produced sequences for 21 nearly complete and seven partial sets of protein coding mitochondrial genes. Combined with existing sequences for 25 taxa, an improved estimate of basal relationships in Coleoptera was obtained. The procedure could be employed routinely for mitochondrial genome sequencing at the species level, to provide improved species 'barcodes' that currently use the cox1 gene only.

Diagnostic Approach in Infants and Children with Mitochondrial Diseases

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Ching-Shiang Chi

2015-02-01

The purpose of this study is to review the molecular classification scheme and associated phenotypes in infants and children with mitochondrial diseases, in addition to providing an overview of the basic biochemical reactions and genetic characteristics in the mitochondrion, clinical manifestations, and diagnostic methods. A diagnostic algorithm for identifying mitochondrial disorders in pediatric neurology patients is proposed.

Development of a Model for the Teaching of Mitochondrial DNA

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A.P.S. Souza

2010-05-01

Full Text Available The Cellular Biology and Molecular Biology are fields of Science that use very abstract concepts, because they look into microscopic and molecular aspects of the nature. The process of teaching/learning of those disciplines requires didactic material, as an alternative approach for the students, to increase the chances of understanding these issues and to become an important tool in the synthesis of this knowledge. One of the methods that can be employed is the didactic models based on multimedia, because they allow an easy and fun interaction with these subjects. On this work was created a new educational model that represents the human mitochondrial DNA molecule, mtDNA, in its circular form, using the softwares Excel 2007 and PowerPoint 2007. The model was constructed in hypertext format, which allowed a quick and interactive access to the information contained in the genes found in the L and the H strands of mtDNA, and its function in the mitochondrial processes, like themechanism of energy production that occurs inside of the mitochondria by the coupling of electron transfer and ATP synthesis or still others uses like forensic identification.

Physical exercise in aging human skeletal muscle increases mitochondrial calcium uniporter expression levels and affects mitochondria dynamics.

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Zampieri, Sandra; Mammucari, Cristina; Romanello, Vanina; Barberi, Laura; Pietrangelo, Laura; Fusella, Aurora; Mosole, Simone; Gherardi, Gaia; Höfer, Christian; Löfler, Stefan; Sarabon, Nejc; Cvecka, Jan; Krenn, Matthias; Carraro, Ugo; Kern, Helmut; Protasi, Feliciano; Musarò, Antonio; Sandri, Marco; Rizzuto, Rosario

2016-12-01

Age-related sarcopenia is characterized by a progressive loss of muscle mass with decline in specific force, having dramatic consequences on mobility and quality of life in seniors. The etiology of sarcopenia is multifactorial and underlying mechanisms are currently not fully elucidated. Physical exercise is known to have beneficial effects on muscle trophism and force production. Alterations of mitochondrial Ca 2+ homeostasis regulated by mitochondrial calcium uniporter (MCU) have been recently shown to affect muscle trophism in vivo in mice. To understand the relevance of MCU-dependent mitochondrial Ca 2+ uptake in aging and to investigate the effect of physical exercise on MCU expression and mitochondria dynamics, we analyzed skeletal muscle biopsies from 70-year-old subjects 9 weeks trained with either neuromuscular electrical stimulation (ES) or leg press. Here, we demonstrate that improved muscle function and structure induced by both trainings are linked to increased protein levels of MCU Ultrastructural analyses by electron microscopy showed remodeling of mitochondrial apparatus in ES-trained muscles that is consistent with an adaptation to physical exercise, a response likely mediated by an increased expression of mitochondrial fusion protein OPA1. Altogether these results indicate that the ES-dependent physiological effects on skeletal muscle size and force are associated with changes in mitochondrial-related proteins involved in Ca 2+ homeostasis and mitochondrial shape. These original findings in aging human skeletal muscle confirm the data obtained in mice and propose MCU and mitochondria-related proteins as potential pharmacological targets to counteract age-related muscle loss. © 2016 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.

Multifunctional Mitochondrial AAA Proteases.

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Glynn, Steven E

2017-01-01

Mitochondria perform numerous functions necessary for the survival of eukaryotic cells. These activities are coordinated by a diverse complement of proteins encoded in both the nuclear and mitochondrial genomes that must be properly organized and maintained. Misregulation of mitochondrial proteostasis impairs organellar function and can result in the development of severe human diseases. ATP-driven AAA+ proteins play crucial roles in preserving mitochondrial activity by removing and remodeling protein molecules in accordance with the needs of the cell. Two mitochondrial AAA proteases, i-AAA and m-AAA, are anchored to either face of the mitochondrial inner membrane, where they engage and process an array of substrates to impact protein biogenesis, quality control, and the regulation of key metabolic pathways. The functionality of these proteases is extended through multiple substrate-dependent modes of action, including complete degradation, partial processing, or dislocation from the membrane without proteolysis. This review discusses recent advances made toward elucidating the mechanisms of substrate recognition, handling, and degradation that allow these versatile proteases to control diverse activities in this multifunctional organelle.

Effects of Mitochondrial Uncoupling Protein 2 Inhibition by Genipin in Human Cumulus Cells

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Hongshan Ge

2015-01-01

Full Text Available UCP2 plays a physiological role by regulating mitochondrial biogenesis, maintaining energy balance, ROS elimination, and regulating cellular autophagy in numerous tissues. But the exact roles of UCP2 in cumulus cells are still not clear. Genipin, a special UCP2 inhibitor, was added into the cultural medium to explore the roles of UCP2 in human cumulus cells. There were no significant differences in ATP and mitochondrial membrane potential levels in cumulus cells from UCP2 inhibiting groups as compared with the control. The levels of ROS and Mn-SOD were markedly elevated after UCP2 inhibited Genipin. However, the ratio of reduced GSH to GSSG significantly declined after treatment with Genipin. UCP2 inhibition by Genipin also resulted in obvious increase in the active caspase-3, which accompanied the decline of caspase-3 mRNA. The level of progesterone in culture medium declined obviously after Genipin treatment. But there was no significant difference in estradiol concentrations. This study indicated that UCP2 is expressed in human cumulus cells and plays important roles on mediate ROS production, apoptotic process, and steroidogenesis, suggesting UCP2 may be involved in regulation of follicle development and oocyte maturation and quality.

Exercise improves mitochondrial and redox-regulated stress responses in the elderly: better late than never!

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Cobley, James N; Moult, Peter R; Burniston, Jatin G; Morton, James P; Close, Graeme L

2015-04-01

Ageing is associated with several physiological declines to both the cardiovascular (e.g. reduced aerobic capacity) and musculoskeletal system (muscle function and mass). Ageing may also impair the adaptive response of skeletal muscle mitochondria and redox-regulated stress responses to an acute exercise bout, at least in mice and rodents. This is a functionally important phenomenon, since (1) aberrant mitochondrial and redox homeostasis are implicated in the pathophysiology of musculoskeletal ageing and (2) the response to repeated exercise bouts promotes exercise adaptations and some of these adaptations (e.g. improved aerobic capacity and exercise-induced mitochondrial remodelling) offset age-related physiological decline. Exercise-induced mitochondrial remodelling is mediated by upstream signalling events that converge on downstream transcriptional co-factors and factors that orchestrate a co-ordinated nuclear and mitochondrial transcriptional response associated with mitochondrial remodelling. Recent translational human investigations have demonstrated similar exercise-induced mitochondrial signalling responses in older compared with younger skeletal muscle, regardless of training status. This is consistent with data indicating normative mitochondrial remodelling responses to long-term exercise training in the elderly. Thus, human ageing is not accompanied by diminished mitochondrial plasticity to acute and chronic exercise stimuli, at least for the signalling pathways measured to date. Exercise-induced increases in reactive oxygen and nitrogen species promote an acute redox-regulated stress response that manifests as increased heat shock protein and antioxidant enzyme content. In accordance with previous reports in rodents and mice, it appears that sedentary ageing is associated with a severely attenuated exercise-induced redox stress response that might be related to an absent redox signal. In this regard, regular exercise training affords some protection

Actin and myosin contribute to mammalian mitochondrial DNA maintenance

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Reyes, A.; He, J.; Mao, C. C.; Bailey, L. J.; Di Re, M.; Sembongi, H.; Kazak, L.; Dzionek, K.; Holmes, J. B.; Cluett, T. J.; Harbour, M. E.; Fearnley, I. M.; Crouch, R. J.; Conti, M. A.; Adelstein, R. S.; Walker, J. E.; Holt, I. J.

2011-01-01

Mitochondrial DNA maintenance and segregation are dependent on the actin cytoskeleton in budding yeast. We found two cytoskeletal proteins among six proteins tightly associated with rat liver mitochondrial DNA: non-muscle myosin heavy chain IIA and β-actin. In human cells, transient gene silencing of MYH9 (encoding non-muscle myosin heavy chain IIA), or the closely related MYH10 gene (encoding non-muscle myosin heavy chain IIB), altered the topology and increased the copy number of mitochondrial DNA; and the latter effect was enhanced when both genes were targeted simultaneously. In contrast, genetic ablation of non-muscle myosin IIB was associated with a 60% decrease in mitochondrial DNA copy number in mouse embryonic fibroblasts, compared to control cells. Gene silencing of β-actin also affected mitochondrial DNA copy number and organization. Protease-protection experiments and iodixanol gradient analysis suggest some β-actin and non-muscle myosin heavy chain IIA reside within human mitochondria and confirm that they are associated with mitochondrial DNA. Collectively, these results strongly implicate the actomyosin cytoskeleton in mammalian mitochondrial DNA maintenance. PMID:21398640

Mitochondrial Diseases: Clinical Features- Management of Patients

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Filiz Koc

2003-02-01

Full Text Available Mitochondria are unique organells which their own DNA in cells. Human mitochondrial DNA is circular, double-stranded molecule and small. Because all mitochondria are contributed by the ovum during the formation of the zygote, the mitochondrial genom is transmitted by maternal inheritance. Multisystem disorders such as deafness, cardiomyopathy, miyopathy can be seen in mitochondrial diseases. [Archives Medical Review Journal 2003; 12(0.100: 14-31

Targeted transgenic overexpression of mitochondrial thymidine kinase (TK2) alters mitochondrial DNA (mtDNA) and mitochondrial polypeptide abundance: transgenic TK2, mtDNA, and antiretrovirals.

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Hosseini, Seyed H; Kohler, James J; Haase, Chad P; Tioleco, Nina; Stuart, Tami; Keebaugh, Erin; Ludaway, Tomika; Russ, Rodney; Green, Elgin; Long, Robert; Wang, Liya; Eriksson, Staffan; Lewis, William

2007-03-01

Mitochondrial toxicity limits nucleoside reverse transcriptase inhibitors (NRTIs) for acquired immune deficiency syndrome. NRTI triphosphates, the active moieties, inhibit human immunodeficiency virus reverse transcriptase and eukaryotic mitochondrial DNA polymerase pol-gamma. NRTI phosphorylation seems to correlate with mitochondrial toxicity, but experimental evidence is lacking. Transgenic mice (TGs) with cardiac overexpression of thymidine kinase isoforms (mitochondrial TK2 and cytoplasmic TK1) were used to study NRTI mitochondrial toxicity. Echocardiography and nuclear magnetic resonance imaging defined cardiac performance and structure. TK gene copy and enzyme activity, mitochondrial (mt) DNA and polypeptide abundance, succinate dehydrogenase and cytochrome oxidase histochemistry, and electron microscopy correlated with transgenesis, mitochondrial structure, and biogenesis. Antiretroviral combinations simulated therapy. Untreated hTK1 or TK2 TGs exhibited normal left ventricle mass. In TK2 TGs, cardiac TK2 gene copy doubled, activity increased 300-fold, and mtDNA abundance doubled. Abundance of the 17-kd subunit of complex I, succinate dehydrogenase histochemical activity, and cristae density increased. NRTIs increased left ventricle mass 20% in TK2 TGs. TK activity increased 3 logs in hTK1 TGs, but no cardiac phenotype resulted. NRTIs abrogated functional effects of transgenically increased TK2 activity but had no effect on TK2 mtDNA abundance. Thus, NRTI mitochondrial phosphorylation by TK2 is integral to clinical NRTI mitochondrial toxicity.

Cdk1, PKCδ and calcineurin-mediated Drp1 pathway contributes to mitochondrial fission-induced cardiomyocyte death

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Zaja, Ivan; Bai, Xiaowen; Liu, Yanan; Kikuchi, Chika; Dosenovic, Svjetlana; Yan, Yasheng; Canfield, Scott G.; Bosnjak, Zeljko J.

2014-01-01

Highlights: • Drp1-mediated increased mitochondrial fission but not fusion is involved the cardiomyocyte death during anoxia-reoxygenation injury. • Reactive oxygen species are upstream initiators of mitochondrial fission. • Increased mitochondrial fission is resulted from Cdk1-, PKCδ-, and calcineurin-mediated Drp1 pathways. - Abstract: Myocardial ischemia–reperfusion (I/R) injury is one of the leading causes of death and disability worldwide. Mitochondrial fission has been shown to be involved in cardiomyocyte death. However, molecular machinery involved in mitochondrial fission during I/R injury has not yet been completely understood. In this study we aimed to investigate molecular mechanisms of controlling activation of dynamin-related protein 1 (Drp1, a key protein in mitochondrial fission) during anoxia-reoxygenation (A/R) injury of HL1 cardiomyocytes. A/R injury induced cardiomyocyte death accompanied by the increases of mitochondrial fission, reactive oxygen species (ROS) production and activated Drp1 (pSer616 Drp1), and decrease of inactivated Drp1 (pSer637 Drp1) while mitochondrial fusion protein levels were not significantly changed. Blocking Drp1 activity with mitochondrial division inhibitor mdivi1 attenuated cell death, mitochondrial fission, and Drp1 activation after A/R. Trolox, a ROS scavenger, decreased pSer616 Drp1 level and mitochondrial fission after A/R. Immunoprecipitation assay further indicates that cyclin dependent kinase 1 (Cdk1) and protein kinase C isoform delta (PKCδ) bind Drp1, thus increasing mitochondrial fission. Inhibiting Cdk1 and PKCδ attenuated the increases in pSer616 Drp1, mitochondrial fission, and cardiomyocyte death. FK506, a calcineurin inhibitor, blocked the decrease in expression of inactivated pSer637 Drp1 and mitochondrial fission. Our findings reveal the following novel molecular mechanisms controlling mitochondrial fission during A/R injury of cardiomyocytes: (1) ROS are upstream initiators of

Cdk1, PKCδ and calcineurin-mediated Drp1 pathway contributes to mitochondrial fission-induced cardiomyocyte death

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Zaja, Ivan [Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI 53226 (United States); Bai, Xiaowen, E-mail: xibai@mcw.edu [Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI 53226 (United States); Liu, Yanan; Kikuchi, Chika; Dosenovic, Svjetlana; Yan, Yasheng; Canfield, Scott G. [Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI 53226 (United States); Bosnjak, Zeljko J. [Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI 53226 (United States); Department of Physiology, Medical College of Wisconsin, Milwaukee, WI 53226 (United States)

2014-10-31

Highlights: • Drp1-mediated increased mitochondrial fission but not fusion is involved the cardiomyocyte death during anoxia-reoxygenation injury. • Reactive oxygen species are upstream initiators of mitochondrial fission. • Increased mitochondrial fission is resulted from Cdk1-, PKCδ-, and calcineurin-mediated Drp1 pathways. - Abstract: Myocardial ischemia–reperfusion (I/R) injury is one of the leading causes of death and disability worldwide. Mitochondrial fission has been shown to be involved in cardiomyocyte death. However, molecular machinery involved in mitochondrial fission during I/R injury has not yet been completely understood. In this study we aimed to investigate molecular mechanisms of controlling activation of dynamin-related protein 1 (Drp1, a key protein in mitochondrial fission) during anoxia-reoxygenation (A/R) injury of HL1 cardiomyocytes. A/R injury induced cardiomyocyte death accompanied by the increases of mitochondrial fission, reactive oxygen species (ROS) production and activated Drp1 (pSer616 Drp1), and decrease of inactivated Drp1 (pSer637 Drp1) while mitochondrial fusion protein levels were not significantly changed. Blocking Drp1 activity with mitochondrial division inhibitor mdivi1 attenuated cell death, mitochondrial fission, and Drp1 activation after A/R. Trolox, a ROS scavenger, decreased pSer616 Drp1 level and mitochondrial fission after A/R. Immunoprecipitation assay further indicates that cyclin dependent kinase 1 (Cdk1) and protein kinase C isoform delta (PKCδ) bind Drp1, thus increasing mitochondrial fission. Inhibiting Cdk1 and PKCδ attenuated the increases in pSer616 Drp1, mitochondrial fission, and cardiomyocyte death. FK506, a calcineurin inhibitor, blocked the decrease in expression of inactivated pSer637 Drp1 and mitochondrial fission. Our findings reveal the following novel molecular mechanisms controlling mitochondrial fission during A/R injury of cardiomyocytes: (1) ROS are upstream initiators of

Gene expression profiling for human iPS-derived motor neurons from sporadic ALS patients reveals a strong association between mitochondrial functions and neurodegeneration

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Alves, Chrystian J.; Dariolli, Rafael; Jorge, Frederico M.; Monteiro, Matheus R.; Maximino, Jessica R.; Martins, Roberto S.; Strauss, Bryan E.; Krieger, José E.; Callegaro, Dagoberto; Chadi, Gerson

2015-01-01

Amyotrophic Lateral Sclerosis (ALS) is a fatal neurodegenerative disease that leads to widespread motor neuron death, general palsy and respiratory failure. The most prevalent sporadic ALS form is not genetically inherited. Attempts to translate therapeutic strategies have failed because the described mechanisms of disease are based on animal models carrying specific gene mutations and thus do not address sporadic ALS. In order to achieve a better approach to study the human disease, human induced pluripotent stem cell (hiPSC)-differentiated motor neurons were obtained from motor nerve fibroblasts of sporadic ALS and non-ALS subjects using the STEMCCA Cre-Excisable Constitutive Polycistronic Lentivirus system and submitted to microarray analyses using a whole human genome platform. DAVID analyses of differentially expressed genes identified molecular function and biological process-related genes through Gene Ontology. REVIGO highlighted the related functions mRNA and DNA binding, GTP binding, transcription (co)-repressor activity, lipoprotein receptor binding, synapse organization, intracellular transport, mitotic cell cycle and cell death. KEGG showed pathways associated with Parkinson's disease and oxidative phosphorylation, highlighting iron homeostasis, neurotrophic functions, endosomal trafficking and ERK signaling. The analysis of most dysregulated genes and those representative of the majority of categorized genes indicates a strong association between mitochondrial function and cellular processes possibly related to motor neuron degeneration. In conclusion, iPSC-derived motor neurons from motor nerve fibroblasts of sporadic ALS patients may recapitulate key mechanisms of neurodegeneration and may offer an opportunity for translational investigation of sporadic ALS. Large gene profiling of differentiated motor neurons from sporadic ALS patients highlights mitochondrial participation in the establishment of autonomous mechanisms associated with sporadic ALS

Molecular phylogeny of the lionfish genera Dendrochirus and Pterois (Scorpaenidae, Pteroinae) based on mitochondrial DNA sequences.

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Kochzius, Marc; Söller, Rainer; Khalaf, Maroof A; Blohm, Dietmar

2003-09-01

This study investigates the molecular phylogeny of seven lionfishes of the genera Dendrochirus and Pterois. MP, ML, and NJ phylogenetic analysis based on 964 bp of partial mitochondrial DNA sequences (cytochrome b and 16S rDNA) revealed two main clades: (1) "Pterois" clade (Pterois miles and Pterois volitans), and (2) "Pteropterus-Dendrochirus" clade (remainder of the sampled species). The position of Dendrochirus brachypterus either basal to the main clades or in the "Pteropterus-Dendrochirus" clade cannot be resolved. However, the molecular phylogeny did not support the current separation of the genera Pterois and Dendrochirus. The siblings P. miles and P. volitans are clearly separated and our results support the proposed allopatric or parapatric distribution in the Indian and Pacific Ocean. However, the present analysis cannot reveal if P. miles and P. volitans are separate species or two populations of a single species, because the observed separation in different clades can be either explained by speciation or lineage sorting. Molecular clock estimates for the siblings P. miles and P. volitans suggest a divergence time of 2.4-8.3 mya, which coincide with geological events that created vicariance between populations of the Indian and Pacific Ocean.

Molecular insights into the m-AAA protease-mediated dislocation of transmembrane helices in the mitochondrial inner membrane.

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Lee, Seoeun; Lee, Hunsang; Yoo, Suji; Kim, Hyun

2017-12-08

Protein complexes involved in respiration, ATP synthesis, and protein import reside in the mitochondrial inner membrane; thus, proper regulation of these proteins is essential for cell viability. The m -AAA protease, a conserved hetero-hexameric AAA (ATPase associated with diverse cellular activities) protease, composed of the Yta10 and Yta12 proteins, regulates mitochondrial proteostasis by mediating protein maturation and degradation. It also recognizes and mediates the dislocation of membrane-embedded substrates, including foreign transmembrane (TM) segments, but the molecular mechanism involved in these processes remains elusive. This study investigated the role of the TM domains in the m -AAA protease by systematic replacement of one TM domain at a time in yeast. Our data indicated that replacement of the Yta10 TM2 domain abolishes membrane dislocation for only a subset of substrates, whereas replacement of the Yta12 TM2 domain impairs membrane dislocation for all tested substrates, suggesting different roles of the TM domains in each m -AAA protease subunit. Furthermore, m -AAA protease-mediated membrane dislocation was impaired in the presence of a large downstream hydrophilic moiety in a membrane substrate. This finding suggested that the m -AAA protease cannot dislocate large hydrophilic domains across the membrane, indicating that the membrane dislocation probably occurs in a lipid environment. In summary, this study highlights previously underappreciated biological roles of TM domains of the m -AAA proteases in mediating the recognition and dislocation of membrane-embedded substrates. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

The mitochondrial genome of Toxocara canis.

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Jex, Aaron R; Waeschenbach, Andrea; Littlewood, D Timothy J; Hu, Min; Gasser, Robin B

2008-08-06

Toxocara canis (Ascaridida: Nematoda), which parasitizes (at the adult stage) the small intestine of canids, can be transmitted to a range of other mammals, including humans, and can cause the disease toxocariasis. Despite its significance as a pathogen, the genetics, epidemiology and biology of this parasite remain poorly understood. In addition, the zoonotic potential of related species of Toxocara, such as T. cati and T. malaysiensis, is not well known. Mitochondrial DNA is known to provide genetic markers for investigations in these areas, but complete mitochondrial genomic data have been lacking for T. canis and its congeners. In the present study, the mitochondrial genome of T. canis was amplified by long-range polymerase chain reaction (long PCR) and sequenced using a primer-walking strategy. This circular mitochondrial genome was 14162 bp and contained 12 protein-coding, 22 transfer RNA, and 2 ribosomal RNA genes consistent for secementean nematodes, including Ascaris suum and Anisakis simplex (Ascaridida). The mitochondrial genome of T. canis provides genetic markers for studies into the systematics, population genetics and epidemiology of this zoonotic parasite and its congeners. Such markers can now be used in prospecting for cryptic species and for exploring host specificity and zoonotic potential, thus underpinning the prevention and control of toxocariasis in humans and other hosts.

The mitochondrial genome of Toxocara canis.

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Aaron R Jex

2008-08-01

Full Text Available Toxocara canis (Ascaridida: Nematoda, which parasitizes (at the adult stage the small intestine of canids, can be transmitted to a range of other mammals, including humans, and can cause the disease toxocariasis. Despite its significance as a pathogen, the genetics, epidemiology and biology of this parasite remain poorly understood. In addition, the zoonotic potential of related species of Toxocara, such as T. cati and T. malaysiensis, is not well known. Mitochondrial DNA is known to provide genetic markers for investigations in these areas, but complete mitochondrial genomic data have been lacking for T. canis and its congeners. In the present study, the mitochondrial genome of T. canis was amplified by long-range polymerase chain reaction (long PCR and sequenced using a primer-walking strategy. This circular mitochondrial genome was 14162 bp and contained 12 protein-coding, 22 transfer RNA, and 2 ribosomal RNA genes consistent for secementean nematodes, including Ascaris suum and Anisakis simplex (Ascaridida. The mitochondrial genome of T. canis provides genetic markers for studies into the systematics, population genetics and epidemiology of this zoonotic parasite and its congeners. Such markers can now be used in prospecting for cryptic species and for exploring host specificity and zoonotic potential, thus underpinning the prevention and control of toxocariasis in humans and other hosts.

The Mitochondrial Genome of Toxocara canis

Science.gov (United States)

Littlewood, D. Timothy J.; Hu, Min; Gasser, Robin B.

2008-01-01

Toxocara canis (Ascaridida: Nematoda), which parasitizes (at the adult stage) the small intestine of canids, can be transmitted to a range of other mammals, including humans, and can cause the disease toxocariasis. Despite its significance as a pathogen, the genetics, epidemiology and biology of this parasite remain poorly understood. In addition, the zoonotic potential of related species of Toxocara, such as T. cati and T. malaysiensis, is not well known. Mitochondrial DNA is known to provide genetic markers for investigations in these areas, but complete mitochondrial genomic data have been lacking for T. canis and its congeners. In the present study, the mitochondrial genome of T. canis was amplified by long-range polymerase chain reaction (long PCR) and sequenced using a primer-walking strategy. This circular mitochondrial genome was 14162 bp and contained 12 protein-coding, 22 transfer RNA, and 2 ribosomal RNA genes consistent for secernentean nematodes, including Ascaris suum and Anisakis simplex (Ascaridida). The mitochondrial genome of T. canis provides genetic markers for studies into the systematics, population genetics and epidemiology of this zoonotic parasite and its congeners. Such markers can now be used in prospecting for cryptic species and for exploring host specificity and zoonotic potential, thus underpinning the prevention and control of toxocariasis in humans and other hosts. PMID:18682828

Detection of mitochondrial DNA deletions in human cells induced by ionizing radiation

International Nuclear Information System (INIS)

Liu, Qing-Jie; Feng, Jiang-Bin; Lu, Xue; Li, Yu-Wen; Chen, De-Qing

2008-01-01

Full text: Purpose: To screen the novel mitochondrial DNA (mt DNA) deletions induced by ionizing radiation, and analyze the several kinds of mt DNA deletions, known as 3895 bp, 889 bp, 7436 bp or 4934 bp deletions. Methods: Long-range PCR with two pairs of primers, which could amplify the whole human mitochondrial genome, was used to analyze the lymphoblastoid cell line before and after exposed to 10 Gy 60 Co γ-rays. The limited condition PCR was used to certify the possible mt DNA deletion showed by long-range PCR. The PCR products were purified, cloned, sequenced and the sequence result were BLASTed. Regular PCR or nest-PCR were used to analyze the 3895 bp, 889 bp, 7436 bp or 4934 bp deletions before and after radiation exposure. The final PCR products were purified, sequenced and BALSTed on standard human mitochondrial genome sequence database. Results: (1) The predicted bands of mt DNA were observed on the control cell lines, and the possible mt DNA deletions were also detected on the irradiated cell lines. The deletions were certified by the limited condition PCR. The sequence BLAST results of the cloned PCR products showed that two kinds of deletions, 7455 bp deletion (nt 475-7929 in heavy strand) and 9225 bp deletion (nt 7714-369 in heavy strand), which were between two 8 bp direct repeats. Further bioinformatics analysis showed that the two deletions were novel deletions. (2) The 889 bp and 3895 bp deletion were not detected for the cell line samples not exposed to 60 Co γ-rays. The 889 bp and 3895 bp deletions were detected on samples exposed to 10 Gy 60 Co γ-rays. The BALST results showed that the 889 bp and 3895 deletions flanked nt 11688 bp-12576, nt 548 bp-4443, respectively. The 7436 bp deletion levels were not changed much before and after irradiation. (3) The 4934 bp deletions had the same pattern as 7436 bp deletion, but it could induced by radiation. Conclusions: Ionizing radiation could induce the human lymphoblastoid two novel mt DNA

Human-gyrovirus-Apoptin triggers mitochondrial death pathway--Nur77 is required for apoptosis triggering.

Science.gov (United States)

Chaabane, Wiem; Cieślar-Pobuda, Artur; El-Gazzah, Mohamed; Jain, Mayur V; Rzeszowska-Wolny, Joanna; Rafat, Mehrdad; Stetefeld, Joerg; Ghavami, Saeid; Los, Marek J

2014-09-01

The human gyrovirus derived protein Apoptin (HGV-Apoptin) a homologue of the chicken anemia virus Apoptin (CAV-Apoptin), a protein with high cancer cells selective toxicity, triggers apoptosis selectively in cancer cells. In this paper, we show that HGV-Apoptin acts independently from the death receptor pathway as it induces apoptosis in similar rates in Jurkat cells deficient in either FADD (fas-associated death domain) function or caspase-8 (key players of the extrinsic pathway) and their parental clones. HGV-Apoptin induces apoptosis via the activation of the mitochondrial intrinsic pathway. It induces both mitochondrial inner and outer membrane permebilization, characterized by the loss of the mitochondrial potential and the release into cytoplasm of the pro-apoptotic molecules including apoptosis inducing factor and cytochrome c. HGV-Apoptin acts via the apoptosome, as lack of expression of apoptotic protease-activating factor 1 in murine embryonic fibroblast strongly protected the cells from HGV-Apoptin-induced apoptosis. Moreover, QVD-oph a broad-spectrum caspase inhibitor delayed HGV-Apoptin-induced death. On the other hand, overexpression of the anti-apoptotic BCL-XL confers resistance to HGV-Apoptin-induced cell death. In contrast, cells that lack the expression of the pro-apoptotic BAX and BAK are protected from HGV-Apoptin induced apoptosis. Furthermore, HGV-Apoptin acts independently from p53 signal but triggers the cytoplasmic translocation of Nur77. Taking together these data indicate that HGV-Apoptin acts through the mitochondrial pathway, in a caspase-dependent manner but independently from the death receptor pathway. Copyright © 2014 Neoplasia Press, Inc. Published by Elsevier Inc. All rights reserved.

Insulin acutely improves mitochondrial function of rat and human skeletal muscle by increasing coupling efficiency of oxidative phosphorylation.

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Nisr, Raid B; Affourtit, Charles

2014-02-01

Insulin is essential for the regulation of fuel metabolism and triggers the uptake of glucose by skeletal muscle. The imported glucose is either stored or broken down, as insulin stimulates glycogenesis and ATP synthesis. The mechanism by which ATP production is increased is incompletely understood at present and, generally, relatively little functional information is available on the effect of insulin on mitochondrial function. In this paper we have exploited extracellular flux technology to investigate insulin effects on the bioenergetics of rat (L6) and human skeletal muscle myoblasts and myotubes. We demonstrate that a 20-min insulin exposure significantly increases (i) the cell respiratory control ratio, (ii) the coupling efficiency of oxidative phosphorylation, and (iii) the glucose sensitivity of anaerobic glycolysis. The improvement of mitochondrial function is explained by an insulin-induced immediate decrease of mitochondrial proton leak. Palmitate exposure annuls the beneficial mitochondrial effects of insulin. Our data improve the mechanistic understanding of insulin-stimulated ATP synthesis, and reveal a hitherto undisclosed insulin sensitivity of cellular bioenergetics that suggests a novel way of detecting insulin responsiveness of cells. © 2013.

Insulin acutely improves mitochondrial function of rat and human skeletal muscle by increasing coupling efficiency of oxidative phosphorylation☆

Science.gov (United States)

Nisr, Raid B.; Affourtit, Charles

2014-01-01

Insulin is essential for the regulation of fuel metabolism and triggers the uptake of glucose by skeletal muscle. The imported glucose is either stored or broken down, as insulin stimulates glycogenesis and ATP synthesis. The mechanism by which ATP production is increased is incompletely understood at present and, generally, relatively little functional information is available on the effect of insulin on mitochondrial function. In this paper we have exploited extracellular flux technology to investigate insulin effects on the bioenergetics of rat (L6) and human skeletal muscle myoblasts and myotubes. We demonstrate that a 20-min insulin exposure significantly increases (i) the cell respiratory control ratio, (ii) the coupling efficiency of oxidative phosphorylation, and (iii) the glucose sensitivity of anaerobic glycolysis. The improvement of mitochondrial function is explained by an insulin-induced immediate decrease of mitochondrial proton leak. Palmitate exposure annuls the beneficial mitochondrial effects of insulin. Our data improve the mechanistic understanding of insulin-stimulated ATP synthesis, and reveal a hitherto undisclosed insulin sensitivity of cellular bioenergetics that suggests a novel way of detecting insulin responsiveness of cells. PMID:24212054

Mitochondrial dysfunction and organophosphorus compounds

Energy Technology Data Exchange (ETDEWEB)

Karami-Mohajeri, Somayyeh [Department of Toxicology and Pharmacology, Faculty of Pharmacy, and Pharmaceutical Sciences Research Center, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Department of Toxicology and Pharmacology, Faculty of Pharmacy, and Pharmaceutical Sciences Research Center, Kerman University of Medical Sciences, Kerman (Iran, Islamic Republic of); Abdollahi, Mohammad, E-mail: Mohammad.Abdollahi@UToronto.Ca [Department of Toxicology and Pharmacology, Faculty of Pharmacy, and Pharmaceutical Sciences Research Center, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of)

2013-07-01

Organophosphorous (OPs) pesticides are the most widely used pesticides in the agriculture and home. However, many acute or chronic poisoning reports about OPs have been published in the recent years. Mitochondria as a site of cellular oxygen consumption and energy production can be a target for OPs poisoning as a non-cholinergic mechanism of toxicity of OPs. In the present review, we have reviewed and criticized all the evidences about the mitochondrial dysfunctions as a mechanism of toxicity of OPs. For this purpose, all biochemical, molecular, and morphological data were retrieved from various studies. Some toxicities of OPs are arisen from dysfunction of mitochondrial oxidative phosphorylation through alteration of complexes I, II, III, IV and V activities and disruption of mitochondrial membrane. Reductions of adenosine triphosphate (ATP) synthesis or induction of its hydrolysis can impair the cellular energy. The OPs disrupt cellular and mitochondrial antioxidant defense, reactive oxygen species generation, and calcium uptake and promote oxidative and genotoxic damage triggering cell death via cytochrome C released from mitochondria and consequent activation of caspases. The mitochondrial dysfunction induced by OPs can be restored by use of antioxidants such as vitamin E and C, alpha-tocopherol, electron donors, and through increasing the cytosolic ATP level. However, to elucidate many aspect of mitochondrial toxicity of Ops, further studies should be performed. - Highlights: • As a non-cholinergic mechanism of toxicity, mitochondria is a target for OPs. • OPs affect action of complexes I, II, III, IV and V in the mitochondria. • OPs reduce mitochondrial ATP. • OPs promote oxidative and genotoxic damage via release of cytochrome C from mitochondria. • OP-induced mitochondrial dysfunction can be restored by increasing the cytosolic ATP.

Mitochondrial dysfunction and organophosphorus compounds

International Nuclear Information System (INIS)

Karami-Mohajeri, Somayyeh; Abdollahi, Mohammad

2013-01-01

Organophosphorous (OPs) pesticides are the most widely used pesticides in the agriculture and home. However, many acute or chronic poisoning reports about OPs have been published in the recent years. Mitochondria as a site of cellular oxygen consumption and energy production can be a target for OPs poisoning as a non-cholinergic mechanism of toxicity of OPs. In the present review, we have reviewed and criticized all the evidences about the mitochondrial dysfunctions as a mechanism of toxicity of OPs. For this purpose, all biochemical, molecular, and morphological data were retrieved from various studies. Some toxicities of OPs are arisen from dysfunction of mitochondrial oxidative phosphorylation through alteration of complexes I, II, III, IV and V activities and disruption of mitochondrial membrane. Reductions of adenosine triphosphate (ATP) synthesis or induction of its hydrolysis can impair the cellular energy. The OPs disrupt cellular and mitochondrial antioxidant defense, reactive oxygen species generation, and calcium uptake and promote oxidative and genotoxic damage triggering cell death via cytochrome C released from mitochondria and consequent activation of caspases. The mitochondrial dysfunction induced by OPs can be restored by use of antioxidants such as vitamin E and C, alpha-tocopherol, electron donors, and through increasing the cytosolic ATP level. However, to elucidate many aspect of mitochondrial toxicity of Ops, further studies should be performed. - Highlights: • As a non-cholinergic mechanism of toxicity, mitochondria is a target for OPs. • OPs affect action of complexes I, II, III, IV and V in the mitochondria. • OPs reduce mitochondrial ATP. • OPs promote oxidative and genotoxic damage via release of cytochrome C from mitochondria. • OP-induced mitochondrial dysfunction can be restored by increasing the cytosolic ATP

Mitochondrial Stress Signalling: HTRA2 and Parkinson's Disease

Directory of Open Access Journals (Sweden)

Enrico Desideri

2012-01-01

Full Text Available Mitochondria are cellular energy generators whose activity requires a continuous supply of oxygen. Recent genetic analysis has suggested that defects in mitochondrial quality control may be key factors in the development of Parkinson’s disease (PD. Mitochondria have a crucial role in supplying energy to the brain, and their deterioration can affect the function and viability of neurons, contributing to neurodegeneration. These organelles can sow the seeds of their own demise because they generate damaging oxygen-free radicals as a byproduct of their intrinsic physiological functions. Mitochondria have therefore evolved specific molecular quality control mechanisms to compensate for the action of damaging agents such as oxygen-free radicals. PTEN-induced putative kinase 1 (PINK1 and high-temperature-regulated A2 (HTRA2, a mitochondrial protease, have recently been proposed to be key modulators of mitochondrial molecular quality control. Here, we review some of the most recent advances in our understanding of mitochondria stress-control pathways, focusing on how signalling by the p38 stress kinase pathway may regulate mitochondrial stress by modulating the activity of HTRA2 via PINK1 and cyclin-dependent kinase 5 (CDK5. We also propose how defects in this pathway may contribute to PD.

Quality control of mitochondria during aging: is there a good and a bad side of mitochondrial dynamics?

Science.gov (United States)

Figge, Marc Thilo; Osiewacz, Heinz D; Reichert, Andreas S

2013-04-01

Maintenance of functional mitochondria is essential in order to prevent degenerative processes leading to disease and aging. Mitochondrial dynamics plays a crucial role in ensuring mitochondrial quality but may also generate and spread molecular damage through a population of mitochondria. Computational simulations suggest that this dynamics is advantageous when mitochondria are not or only marginally damaged. In contrast, at a higher degree of damage, mitochondrial dynamics may be disadvantageous. Deceleration of fusion-fission cycles could be one way to adapt to this situation and to delay a further decline in mitochondrial quality. However, this adaptive response makes the mitochondrial network more vulnerable to additional molecular damage. The "mitochondrial infectious damage adaptation" (MIDA) model explains a number of inconsistent and counterintuitive data such as the "clonal expansion" of mutant mitochondrial DNA. We propose that mitochondrial dynamics is a double-edged sword and suggest ways to test this experimentally. Copyright © 2013 WILEY Periodicals, Inc.

Mitochondrial electron transport is inhibited by disappearance of metallothionein in human bronchial epithelial cells following exposure to silver nitrate.

Science.gov (United States)

Miyayama, Takamitsu; Arai, Yuta; Suzuki, Noriyuki; Hirano, Seishiro

2013-03-08

Silver (Ag) possesses antibacterial activity and has been used in wound dressings and deodorant powders worldwide. However, the metabolic behavior and biological roles of Ag in mammals have not been well characterized. In the present study, we exposed human bronchial epithelial cells (BEAS-2B) to AgNO3 and investigated uptake and intracellular distribution of Ag, expression of metallothionein (MT), generation of reactive oxygen species (ROS), and changes in mitochondrial respiration. The culture medium concentration of Ag decreased with time and stabilized at 12h. The concentration of both Ag and MT in the soluble cellular fraction increased up to 3h and then decreased, indicating that cytosolic Ag relocated to the insoluble fraction of the cells. The levels of mRNAs for the major human MT isoforms MT-I and MT-II paralleled with the protein levels of Ag-MT. The intensity of fluorescence derived from ROS was elevated in the mitochondrial region at 24h. Ag decreased mitochondrial oxygen consumption in a dose-dependent manner and the activity of mitochondrial complex I-IV enzymes was significantly inhibited following exposure to Ag. In a separate experiment, we found that hydrogen peroxide (H2O2) at concentrations as low as 0.001% (equivalent to the concentration of H2O2 in Ag-exposed cells) removed Ag from MT. These results suggest MT was decomposed by cytosolic H2O2, and then Ag released from MT relocated to insoluble cellular fractions and inhibited electron chain transfer of mitochondrial complexes, which eventually led to cell damage. Crown Copyright © 2013. Published by Elsevier Ireland Ltd. All rights reserved.

Activation of IGF-1 and insulin signaling pathways ameliorate mitochondrial function and energy metabolism in Huntington's Disease human lymphoblasts.

Science.gov (United States)

Naia, Luana; Ferreira, I Luísa; Cunha-Oliveira, Teresa; Duarte, Ana I; Ribeiro, Márcio; Rosenstock, Tatiana R; Laço, Mário N; Ribeiro, Maria J; Oliveira, Catarina R; Saudou, Frédéric; Humbert, Sandrine; Rego, A Cristina

2015-02-01

Huntington's disease (HD) is an inherited neurodegenerative disease caused by a polyglutamine repeat expansion in the huntingtin protein. Mitochondrial dysfunction associated with energy failure plays an important role in this untreated pathology. In the present work, we used lymphoblasts obtained from HD patients or unaffected parentally related individuals to study the protective role of insulin-like growth factor 1 (IGF-1) versus insulin (at low nM) on signaling and metabolic and mitochondrial functions. Deregulation of intracellular signaling pathways linked to activation of insulin and IGF-1 receptors (IR,IGF-1R), Akt, and ERK was largely restored by IGF-1 and, at a less extent, by insulin in HD human lymphoblasts. Importantly, both neurotrophic factors stimulated huntingtin phosphorylation at Ser421 in HD cells. IGF-1 and insulin also rescued energy levels in HD peripheral cells, as evaluated by increased ATP and phosphocreatine, and decreased lactate levels. Moreover, IGF-1 effectively ameliorated O2 consumption and mitochondrial membrane potential (Δψm) in HD lymphoblasts, which occurred concomitantly with increased levels of cytochrome c. Indeed, constitutive phosphorylation of huntingtin was able to restore the Δψm in lymphoblasts expressing an abnormal expansion of polyglutamines. HD lymphoblasts further exhibited increased intracellular Ca(2+) levels before and after exposure to hydrogen peroxide (H2O2), and decreased mitochondrial Ca(2+) accumulation, being the later recovered by IGF-1 and insulin in HD lymphoblasts pre-exposed to H2O2. In summary, the data support an important role for IR/IGF-1R mediated activation of signaling pathways and improved mitochondrial and metabolic function in HD human lymphoblasts.

The mitochondrial genome of the entomoparasitic green alga helicosporidium.

Directory of Open Access Journals (Sweden)

Jean-François Pombert

Full Text Available BACKGROUND: Helicosporidia are achlorophyllous, non-photosynthetic protists that are obligate parasites of invertebrates. Highly specialized, these pathogens feature an unusual cyst stage that dehisces inside the infected organism and releases a filamentous cell displaying surface projections, which will penetrate the host gut wall and eventually reproduce in the hemolymph. Long classified as incertae sedis or as relatives of other parasites such as Apicomplexa or Microsporidia, the Helicosporidia were surprisingly identified through molecular phylogeny as belonging to the Chlorophyta, a phylum of green algae. Most phylogenetic analyses involving Helicosporidia have placed them within the subgroup Trebouxiophyceae and further suggested a close affiliation between the Helicosporidia and the genus Prototheca. Prototheca species are also achlorophyllous and pathogenic, but they infect vertebrate hosts, inducing protothecosis in humans. The complete plastid genome of an Helicosporidium species was recently described and is a model of compaction and reduction. Here we describe the complete mitochondrial genome sequence of the same strain, Helicosporidium sp. ATCC 50920 isolated from the black fly Simulium jonesi. METHODOLOGY/PRINCIPAL FINDINGS: The circular mapping 49343 bp mitochondrial genome of Helicosporidium closely resembles that of the vertebrate parasite Prototheca wickerhamii. The two genomes share an almost identical gene complement and display a level of synteny that is higher than any other sequenced chlorophyte mitochondrial DNAs. Interestingly, the Helicosporidium mtDNA feature a trans-spliced group I intron, and a second group I intron that contains two open reading frames that appear to be degenerate maturase/endonuclease genes, both rare characteristics for this type of intron. CONCLUSIONS/SIGNIFICANCE: The architecture, genome content, and phylogeny of the Helicosporidium mitochondrial genome are all congruent with its close

Distinctive mitochondrial genome of Calanoid copepod Calanus sinicus with multiple large non-coding regions and reshuffled gene order: Useful molecular markers for phylogenetic and population studies

Science.gov (United States)

2011-01-01

Background Copepods are highly diverse and abundant, resulting in extensive ecological radiation in marine ecosystems. Calanus sinicus dominates continental shelf waters in the northwest Pacific Ocean and plays an important role in the local ecosystem by linking primary production to higher trophic levels. A lack of effective molecular markers has hindered phylogenetic and population genetic studies concerning copepods. As they are genome-level informative, mitochondrial DNA sequences can be used as markers for population genetic studies and phylogenetic studies. Results The mitochondrial genome of C. sinicus is distinct from other arthropods owing to the concurrence of multiple non-coding regions and a reshuffled gene arrangement. Further particularities in the mitogenome of C. sinicus include low A + T-content, symmetrical nucleotide composition between strands, abbreviated stop codons for several PCGs and extended lengths of the genes atp6 and atp8 relative to other copepods. The monophyletic Copepoda should be placed within the Vericrustacea. The close affinity between Cyclopoida and Poecilostomatoida suggests reassigning the latter as subordinate to the former. Monophyly of Maxillopoda is rejected. Within the alignment of 11 C. sinicus mitogenomes, there are 397 variable sites harbouring three 'hotspot' variable sites and three microsatellite loci. Conclusion The occurrence of the circular subgenomic fragment during laboratory assays suggests that special caution should be taken when sequencing mitogenomes using long PCR. Such a phenomenon may provide additional evidence of mitochondrial DNA recombination, which appears to have been a prerequisite for shaping the present mitochondrial profile of C. sinicus during its evolution. The lack of synapomorphic gene arrangements among copepods has cast doubt on the utility of gene order as a useful molecular marker for deep phylogenetic analysis. However, mitochondrial genomic sequences have been valuable markers for

Mitochondrial dysfunction accounts for the stochastic heterogeneity in telomere-dependent senescence.

Directory of Open Access Journals (Sweden)

João F Passos

2007-05-01

Full Text Available Aging is an inherently stochastic process, and its hallmark is heterogeneity between organisms, cell types, and clonal populations, even in identical environments. The replicative lifespan of primary human cells is telomere dependent; however, its heterogeneity is not understood. We show that mitochondrial superoxide production increases with replicative age in human fibroblasts despite an adaptive UCP-2-dependent mitochondrial uncoupling. This mitochondrial dysfunction is accompanied by compromised [Ca(2+]i homeostasis and other indicators of a retrograde response in senescent cells. Replicative senescence of human fibroblasts is delayed by mild mitochondrial uncoupling. Uncoupling reduces mitochondrial superoxide generation, slows down telomere shortening, and delays formation of telomeric gamma-H2A.X foci. This indicates mitochondrial production of reactive oxygen species (ROS as one of the causes of replicative senescence. By sorting early senescent (SES cells from young proliferating fibroblast cultures, we show that SES cells have higher ROS levels, dysfunctional mitochondria, shorter telomeres, and telomeric gamma-H2A.X foci. We propose that mitochondrial ROS is a major determinant of telomere-dependent senescence at the single-cell level that is responsible for cell-to-cell variation in replicative lifespan.

Resveratrol induces mitochondrial biogenesis in endothelial cells.

Science.gov (United States)

Csiszar, Anna; Labinskyy, Nazar; Pinto, John T; Ballabh, Praveen; Zhang, Hanrui; Losonczy, Gyorgy; Pearson, Kevin; de Cabo, Rafael; Pacher, Pal; Zhang, Cuihua; Ungvari, Zoltan

2009-07-01

Pathways that regulate mitochondrial biogenesis are potential therapeutic targets for the amelioration of endothelial dysfunction and vascular disease. Resveratrol was shown to impact mitochondrial function in skeletal muscle and the liver, but its role in mitochondrial biogenesis in endothelial cells remains poorly defined. The present study determined whether resveratrol induces mitochondrial biogenesis in cultured human coronary arterial endothelial cells (CAECs). In CAECs resveratrol increased mitochondrial mass and mitochondrial DNA content, upregulated protein expression of electron transport chain constituents, and induced mitochondrial biogenesis factors (proliferator-activated receptor-coactivator-1alpha, nuclear respiratory factor-1, mitochondrial transcription factor A). Sirtuin 1 (SIRT1) was induced, and endothelial nitric oxide (NO) synthase (eNOS) was upregulated in a SIRT1-dependent manner. Knockdown of SIRT1 (small interfering RNA) or inhibition of NO synthesis prevented resveratrol-induced mitochondrial biogenesis. In aortas of type 2 diabetic (db/db) mice impaired mitochondrial biogenesis was normalized by chronic resveratrol treatment, showing the in vivo relevance of our findings. Resveratrol increases mitochondrial content in endothelial cells via activating SIRT1. We propose that SIRT1, via a pathway that involves the upregulation of eNOS, induces mitochondrial biogenesis. Resveratrol induced mitochondrial biogenesis in the aortas of type 2 diabetic mice, suggesting the potential for new treatment approaches targeting endothelial mitochondria in metabolic diseases.

The role of mitochondrial dysfunction in the progression of Alzheimer’s disease

DEFF Research Database (Denmark)

Desler, Claus; Lillenes, Meryl S.; Tønjum, Tone

2018-01-01

The current molecular understanding of Alzheimer’s disease (AD) has still not resulted in successful interventions. Mitochondrial dysfunction of the AD brain is currently emerging as a hallmark of this disease. One mitochondrial function often affected in AD is oxidative phosphorylation responsible...

Ionizing radiation induces mitochondrial reactive oxygen species production accompanied by upregulation of mitochondrial electron transport chain function and mitochondrial content under control of the cell cycle checkpoint.

Science.gov (United States)

Yamamori, Tohru; Yasui, Hironobu; Yamazumi, Masayuki; Wada, Yusuke; Nakamura, Yoshinari; Nakamura, Hideo; Inanami, Osamu

2012-07-15

Whereas ionizing radiation (Ir) instantaneously causes the formation of water radiolysis products that contain some reactive oxygen species (ROS), ROS are also suggested to be released from biological sources in irradiated cells. It is now becoming clear that these ROS generated secondarily after Ir have a variety of biological roles. Although mitochondria are assumed to be responsible for this Ir-induced ROS production, it remains to be elucidated how Ir triggers it. Therefore, we conducted this study to decipher the mechanism of Ir-induced mitochondrial ROS production. In human lung carcinoma A549 cells, Ir (10 Gy of X-rays) induced a time-dependent increase in the mitochondrial ROS level. Ir also increased mitochondrial membrane potential, mitochondrial respiration, and mitochondrial ATP production, suggesting upregulation of the mitochondrial electron transport chain (ETC) function after Ir. Although we found that Ir slightly enhanced mitochondrial ETC complex II activity, the complex II inhibitor 3-nitropropionic acid failed to reduce Ir-induced mitochondrial ROS production. Meanwhile, we observed that the mitochondrial mass and mitochondrial DNA level were upregulated after Ir, indicating that Ir increased the mitochondrial content of the cell. Because irradiated cells are known to undergo cell cycle arrest under control of the checkpoint mechanisms, we examined the relationships between cell cycle and mitochondrial content and cellular oxidative stress level. We found that the cells in the G2/M phase had a higher mitochondrial content and cellular oxidative stress level than cells in the G1 or S phase, regardless of whether the cells were irradiated. We also found that Ir-induced accumulation of the cells in the G2/M phase led to an increase in cells with a high mitochondrial content and cellular oxidative stress level. This suggested that Ir upregulated mitochondrial ETC function and mitochondrial content, resulting in mitochondrial ROS production, and that

Mitochondrial C4375T mutation might be a molecular risk factor in a maternal Chinese hypertensive family under haplotype C.

Science.gov (United States)

Chen, Hong; Sun, Min; Fan, Zhen; Tong, Maoqing; Chen, Guodong; Li, Danhui; Ye, Jihui; Yang, Yumin; Zhu, Yongding; Zhu, Jianhua

2017-12-04

Here, we reported a Han Chinese essential hypertensive pedigree based on clinical hereditary and molecular data. To know the molecular basis on this family, mitochondrial genome of one proband from the family was identified through direct sequencing analysis. The age of onset year and affected degree of patients are different in this family. And matrilineal family members carrying C4375T mutation and belong to Eastern Asian halopgroup C. Phylogenetic analysis shows 4375C is highly conservative in 17 species. It is suggested that these mutations might participate in the development of hypertension in this family. And halopgroup C might play a modifying role on the phenotype in this Chinese hypertensive family.

Molecular phylogeny of elasmobranchs inferred from mitochondrial and nuclear markers.

Science.gov (United States)

Pavan-Kumar, A; Gireesh-Babu, P; Babu, P P Suresh; Jaiswar, A K; Hari Krishna, V; Prasasd, K Pani; Chaudhari, Aparna; Raje, S G; Chakraborty, S K; Krishna, Gopal; Lakra, W S

2014-01-01

The elasmobranchs (sharks, rays and skates) being the extant survivors of one of the earliest offshoots of the vertebrate evolutionary tree are good model organisms to study the primitive vertebrate conditions. They play a significant role in maintaining the ecological balance and have high economic value. Due to over-exploitation and illegal fishing worldwide, the elasmobranch stocks are being decimated at an alarming rate. Appropriate management measures are necessary for restoring depleted elasmobranch stocks. One approach for restoring stocks is implementation of conservation measures and these measures can be formulated effectively by knowing the evolutionary relationship among the elasmobranchs. In this study, a total of 30 species were chosen for molecular phylogeny studies using mitochondrial cytochrome c oxidase subunit I, 12S ribosomal RNA gene and nuclear Internal Transcribed Spacer 2. Among different genes, the combined dataset of COI and 12S rRNA resulted in a well resolved tree topology with significant bootstrap/posterior probabilities values. The results supported the reciprocal monophyly of sharks and batoids. Within Galeomorphii, Heterodontiformes (bullhead sharks) formed as a sister group to Lamniformes (mackerel sharks): Orectolobiformes (carpet sharks) and to Carcharhiniformes (ground sharks). Within batoids, the Myliobatiformes formed a monophyly group while Pristiformes (sawfishes) and Rhinobatiformes (guitar fishes) formed a sister group to all other batoids.

Selenium supplementation induces mitochondrial biogenesis in trophoblasts

Czech Academy of Sciences Publication Activity Database

Khera, A.; Dong, L. F.; Holland, O.; Vanderlelie, J.; Pasdar, E.A.; Neužil, Jiří; Perkins, A.V.

2015-01-01

Roč. 36, č. 8 (2015), s. 363-369 ISSN 0143-4004 Institutional support: RVO:86652036 Keywords : Selenium * Reactive oxygen species * Mitochondrial biogenesis Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 2.972, year: 2015

Influence of erythrocyte oxygenation and intravascular ATP on resting and exercising skeletal muscle blood flow in humans with mitochondrial myopathy

DEFF Research Database (Denmark)

Jeppesen, Tina D; Vissing, John; González-Alonso, José

2012-01-01

Oxygen (O(2)) extraction is impaired in exercising skeletal muscle of humans with mutations of mitochondrial DNA (mtDNA), but the muscle hemodynamic response to exercise has never been directly investigated. This study sought to examine the extent to which human skeletal muscle perfusion can incr...

Defect in mitochondrial functions in damaged human mitral valve

OpenAIRE

Shinde, Santosh; Kumar, Pawan; Mishra, Kaushala; Patil, Neela

2006-01-01

Mitochondrial diseases are a heterogeneous group of disorders in which a primary mitochondrial dysfunction is proven by morphological, biochemical, and genetic examinations. The mitral valve has important function in the regulation of blood flow from one chamber to another. Often, the mitral valve becomes abnormal with age, in Rheumatic fever or it is abnormal from birth (Congenital) or it can be destroyed by infection i.e. bacterial endocarditis and needs replacement. Myocardial function dep...

Mitochondrial Reactive Oxygen Species in Lipotoxic Hearts Induce Post-Translational Modifications of AKAP121, DRP1, and OPA1 That Promote Mitochondrial Fission.

Science.gov (United States)

Tsushima, Kensuke; Bugger, Heiko; Wende, Adam R; Soto, Jamie; Jenson, Gregory A; Tor, Austin R; McGlauflin, Rose; Kenny, Helena C; Zhang, Yuan; Souvenir, Rhonda; Hu, Xiao X; Sloan, Crystal L; Pereira, Renata O; Lira, Vitor A; Spitzer, Kenneth W; Sharp, Terry L; Shoghi, Kooresh I; Sparagna, Genevieve C; Rog-Zielinska, Eva A; Kohl, Peter; Khalimonchuk, Oleh; Schaffer, Jean E; Abel, E Dale

2018-01-05

Cardiac lipotoxicity, characterized by increased uptake, oxidation, and accumulation of lipid intermediates, contributes to cardiac dysfunction in obesity and diabetes mellitus. However, mechanisms linking lipid overload and mitochondrial dysfunction are incompletely understood. To elucidate the mechanisms for mitochondrial adaptations to lipid overload in postnatal hearts in vivo. Using a transgenic mouse model of cardiac lipotoxicity overexpressing ACSL1 (long-chain acyl-CoA synthetase 1) in cardiomyocytes, we show that modestly increased myocardial fatty acid uptake leads to mitochondrial structural remodeling with significant reduction in minimum diameter. This is associated with increased palmitoyl-carnitine oxidation and increased reactive oxygen species (ROS) generation in isolated mitochondria. Mitochondrial morphological changes and elevated ROS generation are also observed in palmitate-treated neonatal rat ventricular cardiomyocytes. Palmitate exposure to neonatal rat ventricular cardiomyocytes initially activates mitochondrial respiration, coupled with increased mitochondrial polarization and ATP synthesis. However, long-term exposure to palmitate (>8 hours) enhances ROS generation, which is accompanied by loss of the mitochondrial reticulum and a pattern suggesting increased mitochondrial fission. Mechanistically, lipid-induced changes in mitochondrial redox status increased mitochondrial fission by increased ubiquitination of AKAP121 (A-kinase anchor protein 121) leading to reduced phosphorylation of DRP1 (dynamin-related protein 1) at Ser637 and altered proteolytic processing of OPA1 (optic atrophy 1). Scavenging mitochondrial ROS restored mitochondrial morphology in vivo and in vitro. Our results reveal a molecular mechanism by which lipid overload-induced mitochondrial ROS generation causes mitochondrial dysfunction by inducing post-translational modifications of mitochondrial proteins that regulate mitochondrial dynamics. These findings provide a

Resveratrol-Sensitized UVA Induced Apoptosis in Human Keratinocytes through Mitochondrial Oxidative Stress and Pore Opening

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Boyer, Jean Z; Jandova, Jana; Janda, Jaroslav; Vleugels, Frank R; Elliott, David; Sligh, James E

2012-01-01

Resveratrol (3, 5, 4′-trihydroxy- trans- stilbene), a polyphenol compound, is derived from natural products such as the skin of red grapes, blueberries and cranberries. Resveratrol not only exhibits antioxidant, cardioprotection, and anti-aging properties, but can also inhibit cancer cell growth and induce apoptosis. It has been shown that resveratrol inhibits the activation of Nf-kB and subsequently down regulates the expression of Nf-kB regulated genes such as interleukin-2 and Bcl-2, leading to cell cycle arrest and increased apoptosis in multiple myeloma cells. In the skin, resveratrol has been reported to sensitize keratinocytes to UVA induced apoptosis. However, the effect of resveratrol on opening of the mitochondrial permeability transition pore has not been previously examined. Our data show that UVA (14J/cm2) along with resveratrol causes massive oxidative stress in mitochondria. As a consequence of oxidative stress, the mitochondrial membrane potential decreases which results in opening of the mitochondrial pores ultimately leading to apoptosis in human keratinocytes. These results may have clinical implications for development of future chemotherapeutic treatment for tumors of the skin. PMID:22673012

How do yeast sense mitochondrial dysfunction?

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Dmitry A. Knorre

2016-09-01

Full Text Available Apart from energy transformation, mitochondria play important signaling roles. In yeast, mitochondrial signaling relies on several molecular cascades. However, it is not clear how a cell detects a particular mitochondrial malfunction. The problem is that there are many possible manifestations of mitochondrial dysfunction. For example, exposure to the specific antibiotics can either decrease (inhibitors of respiratory chain or increase (inhibitors of ATP-synthase mitochondrial transmembrane potential. Moreover, even in the absence of the dysfunctions, a cell needs feedback from mitochondria to coordinate mitochondrial biogenesis and/or removal by mitophagy during the division cycle. To cope with the complexity, only a limited set of compounds is monitored by yeast cells to estimate mitochondrial functionality. The known examples of such compounds are ATP, reactive oxygen species, intermediates of amino acids synthesis, short peptides, Fe-S clusters and heme, and also the precursor proteins which fail to be imported by mitochondria. On one hand, the levels of these molecules depend not only on mitochondria. On the other hand, these substances are recognized by the cytosolic sensors which transmit the signals to the nucleus leading to general, as opposed to mitochondria-specific, transcriptional response. Therefore, we argue that both ways of mitochondria-to-nucleus communication in yeast are mostly (if not completely unspecific, are mediated by the cytosolic signaling machinery and strongly depend on cellular metabolic state.

Characterization of mitochondrial proteome in a severe case of ETF-QO deficiency.

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Rocha, H; Ferreira, R; Carvalho, J; Vitorino, R; Santa, C; Lopes, L; Gregersen, N; Vilarinho, L; Amado, F

2011-12-10

Multiple acyl-CoA dehydrogenase deficiency (MADD) is a mitochondrial fatty acid oxidation disorder caused by mutations that affect electron transfer flavoprotein (ETF) or ETF:ubiquinone oxidoreductase (ETF-QO) or even due to unidentified disturbances of riboflavin metabolism. Besides all the available data on the molecular basis of FAO disorders, including MADD, the pathophysiological mechanisms underlying clinical phenotype development, namely at the mitochondrial level, are poorly understood. In order to contribute to the elucidation of these mechanisms, we isolated mitochondria from cultured fibroblasts, from a patient with a severe MADD presentation due to ETF-QO deficiency, characterize its mitochondrial proteome and compare it with normal controls. The used approach (2-DE-MS/MS) allowed the positive identification of 287 proteins in both patient and controls, presenting 35 of the significant differences in their relative abundance. Among the differentially expressed are proteins associated to binding/folding functions, mitochondrial antioxidant enzymes as well as proteins associated to apoptotic events. The overexpression of chaperones like Hsp60 or mitochondrial Grp75, antioxidant enzymes and apoptotic proteins reflects the mitochondrial response to a complete absence of ETF-QO. Our study provides a global perspective of the mitochondrial proteome plasticity in a severe case of MADD and highlights the main molecular pathways involved in its pathogenesis. Copyright © 2011 Elsevier B.V. All rights reserved.

Mitochondrial Effects of PGC-1alpha Silencing in MPP+ Treated Human SH-SY5Y Neuroblastoma Cells

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Qinyong Ye

2017-05-01

Full Text Available The dopaminergic neuron degeneration and loss that occurs in Parkinson’s disease (PD has been tightly linked to mitochondrial dysfunction. Although the aged-related cause of the mitochondrial defect observed in PD patients remains unclear, nuclear genes are of potential importance to mitochondrial function. Human peroxisome proliferator-activated receptor γ coactivator-1alpha (PGC-1α is a multi-functional transcription factor that tightly regulates mitochondrial biogenesis and oxidative capacity. The goal of the present study was to explore the potential pathogenic effects of interference by the PGC-1α gene on N-methyl-4-phenylpyridinium ion (MPP+-induced SH-SY5Y cells. We utilized RNA interference (RNAi technology to probe the pathogenic consequences of inhibiting PGC-1α in the SH-SY5Y cell line. Remarkably, a reduction in PGC-1α resulted in the reduction of mitochondrial membrane potential, intracellular ATP content and intracellular H2O2 generation, leading to the translocation of cytochrome c (cyt c to the cytoplasm in the MPP+-induced PD cell model. The expression of related proteins in the signaling pathway (e.g., estrogen-related receptor α (ERRα, nuclear respiratory factor 1 (NRF-1, NRF-2 and Peroxisome proliferator-activated receptor γ (PPARγ also decreased. Our finding indicates that small interfering RNA (siRNA interference targeting the PGC-1α gene could inhibit the function of mitochondria in several capacities and that the PGC-1α gene may modulate mitochondrial function by regulating the expression of ERRα, NRF-1, NRF-2 and PPARγ. Thus, PGC-1α can be considered a potential therapeutic target for PD.

IDENTIFICATION OF PARAMECIUM BURSARIA SYNGENS THROUGH MOLECULAR MARKERS – COMPARATIVE ANALYSIS OF MITOCHONDRIAL CYTOCHROME C OXIDASE SUBUNIT I (COI

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Patrycja Zagata

2014-08-01

Full Text Available The aim of this study is an identification of Paramecium bursaria syngens originating from different geographical locations and proving the correlation between distributions and belonging to any of five syngens. Ten strains of Paramecium bursaria belonging to five different syngens and strain of Paramecium multimicronucleatum were investigated using molecular marker — mitochondrial cytochrome c oxidase subunit I (COI. According to results, obtained in this study, using phylogenetic methods like Neighbor Joining (NJ and Maximum Likelihood (ML, relationship between analyzing strains through their clustering in clusters and correlation between strains belonging to any syngen and syngen’s distribution was confirmed. Phylograms constructed using NJ and ML methods revealed strains’ grouping in five clusters. Results which were obtained revealed usefulness of COI as a biomarker, which is important in identification of Paramecium bursaria syngens. This reports to a great potential of COI as a molecular marker and obtaining dependable results through combination of molecular methods with classical ones.

Molecular analyses reveal two geographic and genetic lineages for tapeworms, Taenia solium and Taenia saginata, from Ecuador using mitochondrial DNA.

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Solano, Danilo; Navarro, Juan Carlos; León-Reyes, Antonio; Benítez-Ortiz, Washington; Rodríguez-Hidalgo, Richar

2016-12-01

Tapeworms Taenia solium and Taenia saginata are the causative agents of taeniasis/cysticercosis. These are diseases with high medical and veterinary importance due to their impact on public health and rural economy in tropical countries. The re-emergence of T. solium as a result of human migration, the economic burden affecting livestock industry, and the large variability of symptoms in several human cysticercosis, encourage studies on genetic diversity, and the identification of these parasites with molecular phylogenetic tools. Samples collected from the Ecuadorian provinces: Loja, Guayas, Manabí, Tungurahua (South), and Imbabura, Pichincha (North) from 2000 to 2012 were performed under Maximum Parsimony analyses and haplotype networks using partial sequences of mitochondrial DNA, cytochrome oxidase subunit I (COI) and NADH subunit I (NDI), from Genbank and own sequences of Taenia solium and Taenia saginata from Ecuador. Both species have shown reciprocal monophyly, which confirms its molecular taxonomic identity. The COI and NDI genes results suggest phylogenetic structure for both parasite species from south and north of Ecuador. In T. solium, both genes gene revealed greater geographic structure, whereas in T. saginata, the variability for both genes was low. In conclusion, COI haplotype networks of T. solium suggest two geographical events in the introduction of this species in Ecuador (African and Asian lineages) and occurring sympatric, probably through the most common routes of maritime trade between the XV-XIX centuries. Moreover, the evidence of two NDI geographical lineages in T. solium from the north (province of Imbabura) and the south (province of Loja) of Ecuador derivate from a common Indian ancestor open new approaches for studies on genetic populations and eco-epidemiology. Copyright © 2016 Elsevier Inc. All rights reserved.

Highly rearranged mitochondrial genome in Nycteria parasites (Haemosporidia) from bats.

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Karadjian, Gregory; Hassanin, Alexandre; Saintpierre, Benjamin; Gembu Tungaluna, Guy-Crispin; Ariey, Frederic; Ayala, Francisco J; Landau, Irene; Duval, Linda

2016-08-30

Haemosporidia parasites have mostly and abundantly been described using mitochondrial genes, and in particular cytochrome b (cytb). Failure to amplify the mitochondrial cytb gene of Nycteria parasites isolated from Nycteridae bats has been recently reported. Bats are hosts to a diverse and profuse array of Haemosporidia parasites that remain largely unstudied. There is a need to obtain more molecular data from chiropteran parasites. Such data would help to better understand the evolutionary history of Haemosporidia, which notably include the Plasmodium parasites, malaria's agents. We use next-generation sequencing to obtain the complete mitochondrial genome of Nycteria parasites from African Nycteris grandis (Nycteridae) and Rhinolophus alcyone (Rhinolophidae) and Asian Megaderma spasma (Megadermatidae). We report four complete mitochondrial genomes, including two rearranged mitochondrial genomes within Haemosporidia. Our results open outlooks into potentially undiscovered Haemosporidian diversity.

Deconstructing Mitochondrial Dysfunction in Alzheimer Disease

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Vega García-Escudero

2013-01-01

Full Text Available There is mounting evidence showing that mitochondrial damage plays an important role in Alzheimer disease. Increased oxygen species generation and deficient mitochondrial dynamic balance have been suggested to be the reason as well as the consequence of Alzheimer-related pathology. Mitochondrial damage has been related to amyloid-beta or tau pathology or to the presence of specific presenilin-1 mutations. The contribution of these factors to mitochondrial dysfunction is reviewed in this paper. Due to the relevance of mitochondrial alterations in Alzheimer disease, recent works have suggested the therapeutic potential of mitochondrial-targeted antioxidant. On the other hand, autophagy has been demonstrated to play a fundamental role in Alzheimer-related protein stress, and increasing data shows that this pathway is altered in the disease. Moreover, mitochondrial alterations have been related to an insufficient clearance of dysfunctional mitochondria by autophagy. Consequently, different approaches for the removal of damaged mitochondria or to decrease the related oxidative stress in Alzheimer disease have been described. To understand the role of mitochondrial function in Alzheimer disease it is necessary to generate human cellular models which involve living neurons. We have summarized the novel protocols for the generation of neurons by reprogramming or direct transdifferentiation, which offer useful tools to achieve this result.

The clinical, biochemical and genetic features associated with RMND1-related mitochondrial disease

DEFF Research Database (Denmark)

Ng, Yi Shiau; Alston, Charlotte L; Diodato, Daria

2016-01-01

BACKGROUND: Mutations in the RMND1 (Required for Meiotic Nuclear Division protein 1) gene have recently been linked to infantile onset mitochondrial disease characterised by multiple mitochondrial respiratory chain defects. METHODS: We summarised the clinical, biochemical and molecular genetic in...

Molecular phylogeny of the spoonbills (Aves: Threskiornithidae) based on mitochondrial DNA

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Chesser, R. Terry; Yeung, Carol K.L.; Yao, Cheng-Te; Tian, Xiu-Hua; Li, Shou-Hsien

2010-01-01

Spoonbills (genus Platalea) are a small group of wading birds, generally considered to constitute the subfamily Plataleinae (Aves: Threskiornithidae). We reconstructed phylogenetic relationships among the six species of spoonbills using variation in sequences of the mitochondrial genes ND2 and cytochrome b (total 1796 bp). Topologies of phylogenetic trees reconstructed using maximum likelihood, maximum parsimony, and Bayesian analyses were virtually identical and supported monophyly of the spoonbills. Most relationships within Platalea received strong support: P. minor and P. regia were closely related sister species, P. leucorodia was sister to the minor-regia clade, and P. alba was sister to the minor-regia-leucorodia clade. Relationships of P. flavipes and P. ajaja were less well resolved: these species either formed a clade that was sister to the four-species clade, or were successive sisters to this clade. This phylogeny is consistent with ideas of relatedness derived from spoonbill morphology. Our limited sampling of the Threskiornithinae (ibises), the putative sister group to the spoonbills, indicated that this group is paraphyletic, in agreement with previous molecular data; this suggests that separation of the Threskiornithidae into subfamilies Plataleinae and Threskiornithinae may not be warranted.

V-MitoSNP: visualization of human mitochondrial SNPs

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Tsui Ke-Hung

2006-08-01

Full Text Available Abstract Background Mitochondrial single nucleotide polymorphisms (mtSNPs constitute important data when trying to shed some light on human diseases and cancers. Unfortunately, providing relevant mtSNP genotyping information in mtDNA databases in a neatly organized and transparent visual manner still remains a challenge. Amongst the many methods reported for SNP genotyping, determining the restriction fragment length polymorphisms (RFLPs is still one of the most convenient and cost-saving methods. In this study, we prepared the visualization of the mtDNA genome in a way, which integrates the RFLP genotyping information with mitochondria related cancers and diseases in a user-friendly, intuitive and interactive manner. The inherent problem associated with mtDNA sequences in BLAST of the NCBI database was also solved. Description V-MitoSNP provides complete mtSNP information for four different kinds of inputs: (1 color-coded visual input by selecting genes of interest on the genome graph, (2 keyword search by locus, disease and mtSNP rs# ID, (3 visualized input of nucleotide range by clicking the selected region of the mtDNA sequence, and (4 sequences mtBLAST. The V-MitoSNP output provides 500 bp (base pairs flanking sequences for each SNP coupled with the RFLP enzyme and the corresponding natural or mismatched primer sets. The output format enables users to see the SNP genotype pattern of the RFLP by virtual electrophoresis of each mtSNP. The rate of successful design of enzymes and primers for RFLPs in all mtSNPs was 99.1%. The RFLP information was validated by actual agarose electrophoresis and showed successful results for all mtSNPs tested. The mtBLAST function in V-MitoSNP provides the gene information within the input sequence rather than providing the complete mitochondrial chromosome as in the NCBI BLAST database. All mtSNPs with rs number entries in NCBI are integrated in the corresponding SNP in V-MitoSNP. Conclusion V-MitoSNP is a web

Mitochondrial DNA: An Endogenous Trigger for Immune Paralysis.

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Schäfer, Simon T; Franken, Lars; Adamzik, Michael; Schumak, Beatrix; Scherag, André; Engler, Andrea; Schönborn, Niels; Walden, Jennifer; Koch, Susanne; Baba, Hideo A; Steinmann, Jörg; Westendorf, Astrid M; Fandrey, Joachim; Bieber, Thomas; Kurts, Christian; Frede, Stilla; Peters, Jürgen; Limmer, Andreas

2016-04-01

Critically ill patients are at high risk to suffer from sepsis, even in the absence of an initial infectious source, but the molecular mechanisms for their increased sepsis susceptibility, including a suppressed immune system, remain unclear. Although microbes and pathogen-associated molecular pattern are accepted inducers of sepsis and septic immunosuppression, the role of endogenous Toll-like receptor (TLR) ligands, such as mitochondrial DNA (mtDNA), in altering the immune response is unknown. Mitochondrial DNA serum concentrations of the mitochondrial genes D-Loop and adenosine triphosphatase 6 were determined (quantitative polymerase chain reaction) in 165 septic patients and 50 healthy volunteers. Furthermore, cytotoxic T-cell activity was analyzed in wild-type and TLR9 knockout mice, with/without previous mtDNA administration, followed by injection of an ovalbumin-expressing adenoviral vector. Mitochondrial DNA serum concentrations were increased in septic patients (adenosine triphosphatase 6, 123-fold; D-Loop, 76-fold, P < 0.0001) compared with volunteers. Furthermore, a single mtDNA injection caused profound, TLR9-dependent immunosuppression of adaptive T-cell cytotoxicity in wild-type but not in TLR9 knockout mice and evoked various immunosuppressive mechanisms including the destruction of the splenic microstructure, deletion of cross-presenting dendritic cells, and up-regulation of programmed cell death ligand 1 and indoleamine 2,3-dioxygenase. Several of these findings in mice were mirrored in septic patients, and mtDNA concentrations were associated with an increased 30-day mortality. The findings of this study imply that mtDNA, an endogenous danger associated molecular pattern, is a hitherto unknown inducer of septic immunoparalysis and one possible link between initial inflammation and subsequent immunosuppression in critically ill patients.

Molecular and clinical characterization of the myopathic form of mitochondrial DNA depletion syndrome caused by mutations in the thymidine kinase (TK2) gene.

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Chanprasert, Sirisak; Wang, Jing; Weng, Shao-Wen; Enns, Gregory M; Boué, Daniel R; Wong, Brenda L; Mendell, Jerry R; Perry, Deborah A; Sahenk, Zarife; Craigen, William J; Alcala, Francisco J Climent; Pascual, Juan M; Melancon, Serge; Zhang, Victor Wei; Scaglia, Fernando; Wong, Lee-Jun C

2013-01-01

Mitochondrial DNA (mtDNA) depletion syndromes (MDSs) are a clinically and molecularly heterogeneous group of mitochondrial cytopathies characterized by severe mtDNA copy number reduction in affected tissues. Clinically, MDSs are mainly categorized as myopathic, encephalomyopathic, hepatocerebral, or multi-systemic forms. To date, the myopathic form of MDS is mainly caused by mutations in the TK2 gene, which encodes thymidine kinase 2, the first and rate limiting step enzyme in the phosphorylation of pyrimidine nucleosides. We analyzed 9 unrelated families with 11 affected subjects exhibiting the myopathic form of MDS, by sequencing the TK2 gene. Twelve mutations including 4 novel mutations were detected in 9 families. Skeletal muscle specimens were available from 7 out of 11 subjects. Respiratory chain enzymatic activities in skeletal muscle were measured in 6 subjects, and enzymatic activities were reduced in 3 subjects. Quantitative analysis of mtDNA content in skeletal muscle was performed in 5 subjects, and marked mtDNA content reduction was observed in each. In addition, we outline the molecular and clinical characteristics of this syndrome in a total of 52 patients including those previously reported, and a total of 36 TK2 mutations are summarized. Clinically, hypotonia and proximal muscle weakness are the major phenotypes present in all subjects. In summary, our study expands the molecular and clinical spectrum associated with TK2 deficiency. © 2013.

Mitochondrial metabolism and the control of vascular smooth muscle cell proliferation

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Mario eChiong

2014-12-01

Full Text Available Differentiation and dedifferentiation of vascular smooth muscle cells (VSMCs are essential processes of vascular development. VSMCs have biosynthetic, proliferative and contractile roles in the vessel wall. Alterations in the differentiated state of the VSMCs play a critical role in the pathogenesis of a variety of cardiovascular diseases, including atherosclerosis, hypertension and vascular stenosis. This review provides an overview of the current state of knowledge of molecular mechanisms involved in the control of VSMC proliferation, with particular focus on mitochondrial metabolism. Mitochondrial activity can be controlled by regulating mitochondrial dynamics, i.e. mitochondrial fusion and fission, and by regulating mitochondrial calcium handling through the interaction with the endoplasmic reticulum (ER. Alterations in both VSMC proliferation and mitochondrial function can be triggered by dysregulation of mitofusin-2, a small GTPase associated with mitochondrial fusion and mitochondrial-ER interaction. Several lines of evidence highlight the relevance of mitochondrial metabolism in the control of VSMC proliferation, indicating a new area to be explored in the treatment of vascular diseases.

Theranostic properties of a survivin-directed molecular beacon in human melanoma cells.

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Sara Carpi

Full Text Available Survivin is an inhibitor of apoptosis overexpressed in different types of tumors and undetectable in most terminally differentiated normal tissues. In the current study, we sought to evaluate the in vitro theranostic properties of a molecular beacon-oligodeoxynucleotide (MB that targets survivin mRNA. We used laser scanning confocal microscopy to study MB delivery in living cells and real-time PCR and western blot to assess selective survivin-targeting in human malignant melanoma cells. We further assess the pro-apoptotic effect of MB by measuring internucleosomal DNA fragmentation, dissipation of mitochondrial membrane potential (MMP and changes in nuclear morphology. Transfection of MB into A375 and 501 Mel cells generated high signal intensity from the cytoplasm, while no signal was detected in the extracellular environment and in survivin-negative cells (i.e., human melanocytes and monocytes. MB time dependently decreased survivin mRNA and protein expression in melanoma cells with the maximum effect reached at 72 h. Treatment of melanoma cells with MB induced apoptosis by significant changes in MMP, accumulation of histone-complexed DNA fragments in the cytoplasm and nuclear condensation. MB also enhanced the pro-apoptotic effect of standard chemotherapeutic drugs tested at clinically relevant concentrations. The MB tested in the current study conjugates the ability of imaging with the pharmacological silencing activity against survivin mRNA in human melanoma cells and may represent an innovative approach for cancer diagnosis and treatment.

Presence of a mitochondrial-type 70-kDa heat shock protein in Trichomonas vaginalis suggests a very early mitochondrial endosymbiosis in eukaryotes.

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Germot, A; Philippe, H; Le Guyader, H

1996-12-10

Molecular phylogenetic analyses, based mainly on ribosomal RNA, show that three amitochondriate protist lineages, diplomonads, microsporidia, and trichomonads, emerge consistently at the base of the eukaryotic tree before groups having mitochondria. This suggests that these groups could have diverged before the mitochondrial endosymbiosis. Nevertheless, since all these organisms live in anaerobic environments, the absence of mitochondria might be due to secondary loss, as demonstrated for the later emerging eukaryote Entamoeba histolytica. We have now isolated from Trichomonas vaginalis a gene encoding a chaperone protein (HSP70) that in other lineages is addressed to the mitochondrial compartment. The phylogenetic reconstruction unambiguously located this HSP70 within a large set of mitochondrial sequences, itself a sister-group of alpha-purple bacteria. In addition, the T. vaginalis protein exhibits the GDAWV sequence signature, so far exclusively found in mitochondrial HSP70 and in proteobacterial dnaK. Thus mitochondrial endosymbiosis could have occurred earlier than previously assumed. The trichomonad double membrane-bounded organelles, the hydrogenosomes, could have evolved from mitochondria.

A role of taurine in mitochondrial function

DEFF Research Database (Denmark)

Hansen, Svend Høime; Andersen, Mogens Larsen; Cornett, Claus

2010-01-01

The mitochondrial pH gradient across the inner-membrane is stabilised by buffering of the matrix. A low-molecular mass buffer compound has to be localised in the matrix to maintain its alkaline pH value. Taurine is found ubiquitously in animal cells with concentrations in the millimolar range...... enzymes, which are pivotal for beta-oxidation of fatty acids, are demonstrated to have optimal activity in a taurine buffer. By application of the model presented, taurine depletion caused by hyperglycemia could provide a link between mitochondrial dysfunction and diabetes....

The Human Gene SLC25A29, of Solute Carrier Family 25, Encodes a Mitochondrial Transporter of Basic Amino Acids*

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Porcelli, Vito; Fiermonte, Giuseppe; Longo, Antonella; Palmieri, Ferdinando

2014-01-01

The human genome encodes 53 members of the solute carrier family 25 (SLC25), also called the mitochondrial carrier family, many of which have been shown to transport carboxylates, amino acids, nucleotides, and cofactors across the inner mitochondrial membrane, thereby connecting cytosolic and matrix functions. In this work, a member of this family, SLC25A29, previously reported to be a mitochondrial carnitine/acylcarnitine- or ornithine-like carrier, has been thoroughly characterized biochemically. The SLC25A29 gene was overexpressed in Escherichia coli, and the gene product was purified and reconstituted in phospholipid vesicles. Its transport properties and kinetic parameters demonstrate that SLC25A29 transports arginine, lysine, homoarginine, methylarginine and, to a much lesser extent, ornithine and histidine. Carnitine and acylcarnitines were not transported by SLC25A29. This carrier catalyzed substantial uniport besides a counter-exchange transport, exhibited a high transport affinity for arginine and lysine, and was saturable and inhibited by mercurial compounds and other inhibitors of mitochondrial carriers to various degrees. The main physiological role of SLC25A29 is to import basic amino acids into mitochondria for mitochondrial protein synthesis and amino acid degradation. PMID:24652292

The human gene SLC25A29, of solute carrier family 25, encodes a mitochondrial transporter of basic amino acids.

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Porcelli, Vito; Fiermonte, Giuseppe; Longo, Antonella; Palmieri, Ferdinando

2014-05-09

The human genome encodes 53 members of the solute carrier family 25 (SLC25), also called the mitochondrial carrier family, many of which have been shown to transport carboxylates, amino acids, nucleotides, and cofactors across the inner mitochondrial membrane, thereby connecting cytosolic and matrix functions. In this work, a member of this family, SLC25A29, previously reported to be a mitochondrial carnitine/acylcarnitine- or ornithine-like carrier, has been thoroughly characterized biochemically. The SLC25A29 gene was overexpressed in Escherichia coli, and the gene product was purified and reconstituted in phospholipid vesicles. Its transport properties and kinetic parameters demonstrate that SLC25A29 transports arginine, lysine, homoarginine, methylarginine and, to a much lesser extent, ornithine and histidine. Carnitine and acylcarnitines were not transported by SLC25A29. This carrier catalyzed substantial uniport besides a counter-exchange transport, exhibited a high transport affinity for arginine and lysine, and was saturable and inhibited by mercurial compounds and other inhibitors of mitochondrial carriers to various degrees. The main physiological role of SLC25A29 is to import basic amino acids into mitochondria for mitochondrial protein synthesis and amino acid degradation.

The bipartite mitochondrial genome of Ruizia karukerae (Rhigonematomorpha, Nematoda).

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Kim, Taeho; Kern, Elizabeth; Park, Chungoo; Nadler, Steven A; Bae, Yeon Jae; Park, Joong-Ki

2018-05-10

Mitochondrial genes and whole mitochondrial genome sequences are widely used as molecular markers in studying population genetics and resolving both deep and shallow nodes in phylogenetics. In animals the mitochondrial genome is generally composed of a single chromosome, but mystifying exceptions sometimes occur. We determined the complete mitochondrial genome of the millipede-parasitic nematode Ruizia karukerae and found its mitochondrial genome consists of two circular chromosomes, which is highly unusual in bilateral animals. Chromosome I is 7,659 bp and includes six protein-coding genes, two rRNA genes and nine tRNA genes. Chromosome II comprises 7,647 bp, with seven protein-coding genes and 16 tRNA genes. Interestingly, both chromosomes share a 1,010 bp sequence containing duplicate copies of cox2 and three tRNA genes (trnD, trnG and trnH), and the nucleotide sequences between the duplicated homologous gene copies are nearly identical, suggesting a possible recent genesis for this bipartite mitochondrial genome. Given that little is known about the formation, maintenance or evolution of abnormal mitochondrial genome structures, R. karukerae mtDNA may provide an important early glimpse into this process.

Nutritional Ketosis and Mitohormesis: Potential Implications for Mitochondrial Function and Human Health

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Villamena, Frederick A.

2018-01-01

Impaired mitochondrial function often results in excessive production of reactive oxygen species (ROS) and is involved in the etiology of many chronic diseases, including cardiovascular disease, diabetes, neurodegenerative disorders, and cancer. Moderate levels of mitochondrial ROS, however, can protect against chronic disease by inducing upregulation of mitochondrial capacity and endogenous antioxidant defense. This phenomenon, referred to as mitohormesis, is induced through increased reliance on mitochondrial respiration, which can occur through diet or exercise. Nutritional ketosis is a safe and physiological metabolic state induced through a ketogenic diet low in carbohydrate and moderate in protein. Such a diet increases reliance on mitochondrial respiration and may, therefore, induce mitohormesis. Furthermore, the ketone β-hydroxybutyrate (BHB), which is elevated during nutritional ketosis to levels no greater than those resulting from fasting, acts as a signaling molecule in addition to its traditionally known role as an energy substrate. BHB signaling induces adaptations similar to mitohormesis, thereby expanding the potential benefit of nutritional ketosis beyond carbohydrate restriction. This review describes the evidence supporting enhancement of mitochondrial function and endogenous antioxidant defense in response to nutritional ketosis, as well as the potential mechanisms leading to these adaptations. PMID:29607218

Improvement of mitochondrial function and dynamics by the metabolic enhancer piracetam.

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Stockburger, Carola; Kurz, Christopher; Koch, Konrad A; Eckert, Schamim H; Leuner, Kristina; Müller, Walter E

2013-10-01

The metabolic enhancer piracetam is used in many countries to treat cognitive impairment in aging, brain injuries, as well as dementia such as AD (Alzheimer's disease). As a specific feature of piracetam, beneficial effects are usually associated with mitochondrial dysfunction. In previous studies we were able to show that piracetam enhanced ATP production, mitochondrial membrane potential as well as neurite outgrowth in cell and animal models for aging and AD. To investigate further the effects of piracetam on mitochondrial function, especially mitochondrial fission and fusion events, we decided to assess mitochondrial morphology. Human neuroblastoma cells were treated with the drug under normal conditions and under conditions imitating aging and the occurrence of ROS (reactive oxygen species) as well as in stably transfected cells with the human wild-type APP (amyloid precursor protein) gene. This AD model is characterized by expressing only 2-fold more human Aβ (amyloid β-peptide) compared with control cells and therefore representing very early stages of AD when Aβ levels gradually increase over decades. Interestingly, these cells exhibit an impaired mitochondrial function and morphology under baseline conditions. Piracetam is able to restore this impairment and shifts mitochondrial morphology back to elongated forms, whereas there is no effect in control cells. After addition of a complex I inhibitor, mitochondrial morphology is distinctly shifted to punctate forms in both cell lines. Under these conditions piracetam is able to ameliorate morphology in cells suffering from the mild Aβ load, as well as mitochondrial dynamics in control cells.

Mitochondrial dynamics in mammalian health and disease.

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Liesa, Marc; Palacín, Manuel; Zorzano, Antonio

2009-07-01

The meaning of the word mitochondrion (from the Greek mitos, meaning thread, and chondros, grain) illustrates that the heterogeneity of mitochondrial morphology has been known since the first descriptions of this organelle. Such a heterogeneous morphology is explained by the dynamic nature of mitochondria. Mitochondrial dynamics is a concept that includes the movement of mitochondria along the cytoskeleton, the regulation of mitochondrial architecture (morphology and distribution), and connectivity mediated by tethering and fusion/fission events. The relevance of these events in mitochondrial and cell physiology has been partially unraveled after the identification of the genes responsible for mitochondrial fusion and fission. Furthermore, during the last decade, it has been identified that mutations in two mitochondrial fusion genes (MFN2 and OPA1) cause prevalent neurodegenerative diseases (Charcot-Marie Tooth type 2A and Kjer disease/autosomal dominant optic atrophy). In addition, other diseases such as type 2 diabetes or vascular proliferative disorders show impaired MFN2 expression. Altogether, these findings have established mitochondrial dynamics as a consolidated area in cellular physiology. Here we review the most significant findings in the field of mitochondrial dynamics in mammalian cells and their implication in human pathologies.

Investigating the role of melanin in UVA/UVB- and hydrogen peroxide-induced cellular and mitochondrial ROS production and mitochondrial DNA damage in human melanoma cells.

Science.gov (United States)

Swalwell, Helen; Latimer, Jennifer; Haywood, Rachel M; Birch-Machin, Mark A

2012-02-01

Skin cancer incidence is dramatically increasing worldwide, with exposure to ultraviolet radiation (UVR) a predominant factor. The UVA component initiates oxidative stress in human skin, although its exact role in the initiation of skin cancer, particularly malignant melanoma, remains unclear and is controversial because there is evidence for a melanin-dependent mechanism in UVA-linked melanoma studies. Nonpigmented (CHL-1, A375), moderately pigmented (FM55, SKmel23), and highly pigmented (FM94, hyperpigmented FM55) human melanoma cell lines have been used to investigate UVA-induced production of reactive oxygen species using FACS analysis, at both the cellular (dihydrorhodamine-123) and the mitochondrial (MitoSOX) level, where most cellular stress is generated. For the first time, downstream mtDNA damage (utilizing a quantitative long-PCR assay) has been investigated. Using UVA, UVB, and H(2)O(2) as cellular stressors, we have explored the dual roles of melanin as a photoprotector and photosensitizer. The presence of melanin has no influence over cellular oxidative stress generation, whereas, in contrast, melanin protects against mitochondrial superoxide generation and mtDNA damage (one-way ANOVA with post hoc Tukey's analysis, Pmelanin binds directly to DNA, it acts as a direct photosensitizer of mtDNA damage during UVA irradiation (Pmelanin. Copyright © 2011 Elsevier Inc. All rights reserved.

Mitochondrial fission promotes cell migration by Ca2+ /CaMKII/ERK/FAK pathway in hepatocellular carcinoma.

Science.gov (United States)

Sun, Xiacheng; Cao, Haiyan; Zhan, Lei; Yin, Chun; Wang, Gang; Liang, Ping; Li, Jibin; Wang, Zhe; Liu, Bingrong; Huang, Qichao; Xing, Jinliang

2018-07-01

Mitochondrial dynamics of fission and fusion plays critical roles in a diverse range of important cellular functions, and its deregulation has been increasingly implicated in human diseases. Previous studies have shown that increased mitochondrial fission significantly promoted the proliferation of hepatocellular carcinoma (HCC) cells. However, how they influence the migration of tumour cells remained largely unknown. In the present study, we further investigated the effect of mitochondrial fission on the migration and metastasis of hepatocellular carcinoma cells. Moreover, the underlying molecular mechanisms and therapeutic application were explored. Our data showed that dynamin-1-like protein expression was strongly increased in distant metastasis of hepatocellular carcinoma when compared to primary hepatocellular carcinoma. In contrast, the mitochondrial fusion protein mitofusin 1 showed an opposite trend. Moreover, the expression of dynamin-1-like protein and mitofusin 1 was significantly associated with the disease-free survival of hepatocellular carcinoma patients. In addition, our data further showed that mitochondrial fission significantly promoted the reprogramming of focal-adhesion dynamics and lamellipodia formation in hepatocellular carcinoma cells mainly by activating typical Ca 2+ /CaMKII/ERK/FAK pathway. Importantly, treatment with mitochondrial division inhibitor-1 significantly decreased calcium signalling in hepatocellular carcinoma cells and had a potential treatment effect for hepatocellular carcinoma metastasis in vivo. Taken together, our findings demonstrate that mitochondrial fission plays a critical role in the regulation of hepatocellular carcinoma cell migration, which provides strong evidence for this process as a drug target in hepatocellular carcinoma metastasis treatment. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Molecular Structure of Human-Liver Glycogen.

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Bin Deng

Full Text Available Glycogen is a highly branched glucose polymer which is involved in maintaining blood-sugar homeostasis. Liver glycogen contains large composite α particles made up of linked β particles. Previous studies have shown that the binding which links β particles into α particles is impaired in diabetic mice. The present study reports the first molecular structural characterization of human-liver glycogen from non-diabetic patients, using transmission electron microscopy for morphology and size-exclusion chromatography for the molecular size distribution; the latter is also studied as a function of time during acid hydrolysis in vitro, which is sensitive to certain structural features, particularly glycosidic vs. proteinaceous linkages. The results are compared with those seen in mice and pigs. The molecular structural change during acid hydrolysis is similar in each case, and indicates that the linkage of β into α particles is not glycosidic. This result, and the similar morphology in each case, together imply that human liver glycogen has similar molecular structure to those of mice and pigs. This knowledge will be useful for future diabetes drug targets.

Proteomic Profiling of Mitochondrial Enzymes during Skeletal Muscle Aging

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Lisa Staunton

2011-01-01

Full Text Available Mitochondria are of central importance for energy generation in skeletal muscles. Expression changes or functional alterations in mitochondrial enzymes play a key role during myogenesis, fibre maturation, and various neuromuscular pathologies, as well as natural fibre aging. Mass spectrometry-based proteomics suggests itself as a convenient large-scale and high-throughput approach to catalogue the mitochondrial protein complement and determine global changes during health and disease. This paper gives a brief overview of the relatively new field of mitochondrial proteomics and discusses the findings from recent proteomic surveys of mitochondrial elements in aged skeletal muscles. Changes in the abundance, biochemical activity, subcellular localization, and/or posttranslational modifications in key mitochondrial enzymes might be useful as novel biomarkers of aging. In the long term, this may advance diagnostic procedures, improve the monitoring of disease progression, help in the testing of side effects due to new drug regimes, and enhance our molecular understanding of age-related muscle degeneration.

Mitochondrial and Cell Death Mechanisms in Neurodegenerative Diseases

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Lee J. Martin

2010-03-01

Full Text Available Alzheimer’s disease (AD, Parkinson’s disease (PD and amyotrophic lateral sclerosis (ALS are the most common human adult-onset neurodegenerative diseases. They are characterized by prominent age-related neurodegeneration in selectively vulnerable neural systems. Some forms of AD, PD, and ALS are inherited, and genes causing these diseases have been identified. Nevertheless, the mechanisms of the neuronal cell death are unresolved. Morphological, biochemical, genetic, as well as cell and animal model studies reveal that mitochondria could have roles in this neurodegeneration. The functions and properties of mitochondria might render subsets of selectively vulnerable neurons intrinsically susceptible to cellular aging and stress and overlying genetic variations, triggering neurodegeneration according to a cell death matrix theory. In AD, alterations in enzymes involved in oxidative phosphorylation, oxidative damage, and mitochondrial binding of Aβ and amyloid precursor protein have been reported. In PD, mutations in putative mitochondrial proteins have been identified and mitochondrial DNA mutations have been found in neurons in the substantia nigra. In ALS, changes occur in mitochondrial respiratory chain enzymes and mitochondrial cell death proteins. Transgenic mouse models of human neurodegenerative disease are beginning to reveal possible principles governing the biology of selective neuronal vulnerability that implicate mitochondria and the mitochondrial permeability transition pore. This review summarizes how mitochondrial pathobiology might contribute to neuronal death in AD, PD, and ALS and could serve as a target for drug therapy.

Molecular study on three morphotypes of Demodex mites (Acarina: Demodicidae) from dogs.

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de Rojas, Manuel; Riazzo, Cristina; Callejón, Rocío; Guevara, Diego; Cutillas, Cristina

2012-11-01

Canine demodicosis is a severe and highly prevalent dermatologic disease in dogs. Pet dogs can be affected by three recognized Demodex species that can produce clinical effects. In this paper, three morphological types of Demodex mites have been isolated from Spanish dogs. A complete morphobiometrical study of each one has been carried out. Morphological and biometrical studies revealed three closely related populations with some distinctive characteristics and could be identified as Demodex canis, Demodex injai, and Demodex sp. "cornei." Furthermore, one population of D. canis from China, different populations of Demodex folliculorum from human skin (Spain and China), D. folliculorum from human eyelashes (Spain), and Demodex brevis from human skin (China) were considered to find out the level of variation between different species and geographical origin. The aim of the present study is to assess the usefulness of mitochondrial DNA molecular markers in establishing phylogenetic relationships and resolve taxonomic questions in Demodex mites. Molecular studies based on the amplification and sequencing of the 16S rDNA and cytochrome oxidase I mitochondrial genes did not show clear differences between the three morphotypes considered. Furthermore, phylogenetic relationships in Demodex mites were analyzed. The resulting phylogenetic trees show that Demodex species from dogs were gathered together, and populations of D. folliculorum from humans appear together in a different branch; however, D. brevis from humans seemed to be more distant. Our results show that cytochrome oxidase I region is a useful tool to solve different taxonomic questions at the species and population level and to infer phylogenetic relationships in Demodex species. However, 16S mitochondrial rDNA seems a good marker for comparisons at an interspecies level, but not at a population level in this group of mites. Furthermore, from genetic distance and divergence data, we would suggest that D. canis

Prohibitin 1 modulates mitochondrial stress-related autophagy in human colonic epithelial cells.

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Arwa S Kathiria

Full Text Available Autophagy is an adaptive response to extracellular and intracellular stress by which cytoplasmic components and organelles, including damaged mitochondria, are degraded to promote cell survival and restore cell homeostasis. Certain genes involved in autophagy confer susceptibility to Crohn's disease. Reactive oxygen species and pro-inflammatory cytokines such as tumor necrosis factor α (TNFα, both of which are increased during active inflammatory bowel disease, promote cellular injury and autophagy via mitochondrial damage. Prohibitin (PHB, which plays a role in maintaining normal mitochondrial respiratory function, is decreased during active inflammatory bowel disease. Restoration of colonic epithelial PHB expression protects mice from experimental colitis and combats oxidative stress. In this study, we investigated the potential role of PHB in modulating mitochondrial stress-related autophagy in intestinal epithelial cells.We measured autophagy activation in response to knockdown of PHB expression by RNA interference in Caco2-BBE and HCT116 WT and p53 null cells. The effect of exogenous PHB expression on TNFα- and IFNγ-induced autophagy was assessed. Autophagy was inhibited using Bafilomycin A(1 or siATG16L1 during PHB knockdown and the affect on intracellular oxidative stress, mitochondrial membrane potential, and cell viability were determined. The requirement of intracellular ROS in siPHB-induced autophagy was assessed using the ROS scavenger N-acetyl-L-cysteine.TNFα and IFNγ-induced autophagy inversely correlated with PHB protein expression. Exogenous PHB expression reduced basal autophagy and TNFα-induced autophagy. Gene silencing of PHB in epithelial cells induces mitochondrial autophagy via increased intracellular ROS. Inhibition of autophagy during PHB knockdown exacerbates mitochondrial depolarization and reduces cell viability.Decreased PHB levels coupled with dysfunctional autophagy renders intestinal epithelial cells

Phylogenetic analysis of Tibetan mastiffs based on mitochondrial ...

Indian Academy of Sciences (India)

ZHANJUN REN

sites were identified which defined eight haplotypes of which H4 and H8 were unique to Tibetan ... tion rate makes HVRI preferred to study molecular evolution ... Tibetan mastiffs; hypervariable region; genetic diversity; mitochondrial DNA.

Insulin Resistance and Mitochondrial Dysfunction.

Science.gov (United States)

Gonzalez-Franquesa, Alba; Patti, Mary-Elizabeth

2017-01-01

Insulin resistance precedes and predicts the onset of type 2 diabetes (T2D) in susceptible humans, underscoring its important role in the complex pathogenesis of this disease. Insulin resistance contributes to multiple tissue defects characteristic of T2D, including reduced insulin-stimulated glucose uptake in insulin-sensitive tissues, increased hepatic glucose production, increased lipolysis in adipose tissue, and altered insulin secretion. Studies of individuals with insulin resistance, both with established T2D and high-risk individuals, have consistently demonstrated a diverse array of defects in mitochondrial function (i.e., bioenergetics, biogenesis and dynamics). However, it remains uncertain whether mitochondrial dysfunction is primary (critical initiating defect) or secondary to the subtle derangements in glucose metabolism, insulin resistance, and defective insulin secretion present early in the course of disease development. In this chapter, we will present the evidence linking mitochondrial dysfunction and insulin resistance, and review the potential for mitochondrial targets as a therapeutic approach for T2D.

Molecular biology of human muscle disease

Energy Technology Data Exchange (ETDEWEB)

Dunne, P.W.; Epstein, H.F. (Baylor Coll. of Medicine, Houston, TX (United States))

1991-01-01

The molecular revolution that is transforming the entire biomedical field has had far-reaching impact in its application to inherited human muscle disease. The gene for Duchenne muscular dystrophy was one of the first cloned without knowledge of the defective protein product. This success was based upon the availability of key chromosomal aberrations that provided molecular landmarks for the disease locus. Subsequent discoveries regarding the mode of expression for this gene, the structure and localization of its protein product dystrophin, and molecular diagnosis of affected and carrier individuals constitute a paradigm for investigation of human genetics. Finding the gene for myotonic muscular dystrophy is requiring the brute force approach of cloning several million bases of DNA, identifying expressed sequences, and characterizing candidate genes. The gene that causes hypertrophic cardiomyopathy has been found serendipitously to be one of the genetic markers on chromosome 14, the {beta} myosin heavy chain.

Mechanistic perspective of mitochondrial fusion: tubulation vs. fragmentation.

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Escobar-Henriques, Mafalda; Anton, Fabian

2013-01-01

Mitochondrial fusion is a fundamental process driven by dynamin related GTPase proteins (DRPs), in contrast to the general SNARE-dependence of most cellular fusion events. The DRPs Mfn1/Mfn2/Fzo1 and OPA1/Mgm1 are the key effectors for fusion of the mitochondrial outer and inner membranes, respectively. In order to promote fusion, these two DRPs require post-translational modifications and proteolysis. OPA1/Mgm1 undergoes partial proteolytic processing, which results in a combination between short and long isoforms. In turn, ubiquitylation of mitofusins, after oligomerization and GTP hydrolysis, promotes and positively regulates mitochondrial fusion. In contrast, under conditions of mitochondrial dysfunction, negative regulation by proteolysis on these DRPs results in mitochondrial fragmentation. This occurs by complete processing of OPA1 and via ubiquitylation and degradation of mitofusins. Mitochondrial fragmentation contributes to the elimination of damaged mitochondria by mitophagy, and may play a protective role against Parkinson's disease. Moreover, a link of Mfn2 to Alzheimer's disease is emerging and mutations in Mfn2 or OPA1 cause Charcot-Marie-Tooth type 2A neuropathy or autosomal-dominant optic atrophy. Here, we summarize our current understanding on the molecular mechanisms promoting or inhibiting fusion of mitochondrial membranes, which is essential for cellular survival and disease control. This article is part of a Special Issue entitled: Mitochondrial dynamics and physiology. Copyright © 2012 Elsevier B.V. All rights reserved.

Molecular phylogeny of Systellognatha (Plecoptera: Arctoperlaria) inferred from mitochondrial genome sequences.

Science.gov (United States)

Chen, Zhi-Teng; Zhao, Meng-Yuan; Xu, Cheng; Du, Yu-Zhou

2018-05-01

The infraorder Systellognatha is the most species-rich clade in the insect order Plecoptera and includes six families in two superfamilies: Pteronarcyoidea (Pteronarcyidae, Peltoperlidae, and Styloperlidae) and Perloidea (Perlidae, Perlodidae, and Chloroperlidae). To resolve the debatable phylogeny of Systellognatha, we carried out the first mitochondrial phylogenetic analysis covering all the six families, including three newly sequenced mitogenomes from two families (Perlodidae and Peltoperlidae) and 15 published mitogenomes. The three newly reported mitogenomes share conserved mitogenomic features with other sequenced stoneflies. For phylogenetic analyses, we assembled five datasets with two inference methods to assess their influence on topology and nodal support within Systellognatha. The results indicated that inclusion of the third codon positions of PCGs, exclusion of rRNA genes, the use of nucleotide datasets and Bayesian inference could improve the phylogenetic reconstruction of Systellognatha. The monophyly of Perloidea was supported in the mitochondrial phylogeny, but Pteronarcyoidea was recovered as paraphyletic and remained controversial. In this mitochondrial phylogenetic study, the relationships within Systellognatha were recovered as (((Perlidae + (Perlodidae + Chloroperlidae)) + (Pteronarcyidae + Styloperlidae)) + Peltoperlidae). Copyright © 2018 Elsevier B.V. All rights reserved.

Molecular systematics of the freshwater stingrays (myliobatiformes: potamotrygonidae) of the Amazon, Orinoco, Magdalena, Esequibo, Caribbean, and Maracaibo basins (Colombia - Venezuela): evidence from three mitochondrial genes.

Science.gov (United States)

Garcia, David Alejandro; Lasso, Carlos Andres; Morales, Monica; Caballero, Susana Josefina

2016-11-01

Lack of adequate information about the taxonomic and evolutionary relationships, ecology, biology, and distribution of several species belonging to the family Potamotrygonidae makes these species vulnerable to anthropic activities, including commercial overexploitation for the ornamental fish market. The aim of this study was to investigate the systematic relationships among genera and species belonging to this family by analyses of three mitochondrial gene regions. Samples were collected from the main river basins in Colombia and Venezuela for four genera and seven species of the family, as well as for what appear to be unidentified species. Three mitochondrial molecular markers COI, Cytb, and ATP6 were amplified and sequenced. Maximum likelihood and Bayesian inference analysis were performed to obtain topologies for each marker and for a concatenated dataset including the three genes. Small dataset may compromise some methods estimations of sequence divergence in the ATP6 marker. Monophyly of the four genera in Potamotrygonidae was confirmed and phylogenetic relationships among members of the Potamotrygon genus were not clearly resolved. However, results obtained with the molecular marker Cytb appear to offer a good starting point to differentiate among genera and species as a tool that could be used for barcoding. The application of this gene as a barcode could be applied for management and regulation of extraction practices for these genera. Sequencing complete mitochondrial genomes would be the next step for testing evolutionary hypothesis among these genera. Population structure analyses should be undertaken for Paratrygon, Potamotrygon magdalenae and motoro.

Mitochondrial histone-like DNA-binding proteins are essential for normal cell growth and mitochondrial function in Crithidia fasciculata

Czech Academy of Sciences Publication Activity Database

Avliyakulov, N. K.; Lukeš, Julius; Ray, D. S.

2004-01-01

Roč. 3, č. 2 (2004), s. 518-526 ISSN 1535-9778 R&D Projects: GA AV ČR IAA5022302 Institutional research plan: CEZ:AV0Z6022909 Keywords : cell growth * mitochondrial function * Kinetoplastida Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 3.954, year: 2004

[Linezolid-induced Apoptosis through Mitochondrial Damage and Role of Superoxide Dismutase-1 in Human Monocytic Cell Line U937].

Science.gov (United States)

Fujii, Satoshi; Muraoka, Sanae; Miyamoto, Atsushi; Sakurai, Koichi

2018-01-01

 Cytopenia is a major adverse event associated with linezolid therapy. The objective of this study was to examine whether the cytotoxicity of linezolid to eukaryotic cells was associated with mitochondrial dysfunction and apoptosis-like cell death in human leukemic monocyte lymphoma cell line U937. Apoptosis-like cell death was clearly observed when cells were incubated with linezolid, depending on the duration and linezolid concentration. Mitochondrial membrane potential of cells treated with linezolid collapsed in a short period of time, but the number of mitochondria did not decrease. Cytotoxicity of linezolid was relieved by the knockdown of superoxide dismutase-1 in U937 cells. On the other hand, no autophagy was observed in cells treated with linezolid. These results suggest that mitochondrial damages would be linked to the induction of apoptosis in U937 cells treated with linezolid and that its mechanism does not involve autophagy.

Molecular detection of human bacterial pathogens

National Research Council Canada - National Science Library

Liu, Dongyou

2011-01-01

.... Molecular Detection of Human Bacterial Pathogens addresses this issue, with international scientists in respective bacterial pathogen research and diagnosis providing expert summaries on current...

Effect of DHA and CoenzymeQ10 Against Aβ- and Zinc-Induced Mitochondrial Dysfunction in Human Neuronal Cells

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Nadia Sadli

2013-07-01

Full Text Available Background: Beta-amyloid (Aβ protein is a key factor in the pathogenesis of Alzheimer's disease (AD and it has been reported that mitochondria is involved in the biochemical pathway by which Aβ can lead to neuronal dysfunction. Coenzyme Q10 (CoQ10 is an essential cofactor involved in the mitochondrial electron transport chain and has been suggested as a potential therapeutic agent in AD. Zinc toxicity also affects cellular energy production by decreasing oxygen consumption rate (OCR and ATP turnover in human neuronal cells, which can be restored by the neuroprotective effect of docosahexaenoic acid (DHA. Method: In the present study, using Seahorse XF-24 Metabolic Flux Analysis we investigated the effect of DHA and CoQ10 alone and in combination against Aβ- and zinc-mediated changes in the mitochondrial function of M17 neuroblastoma cell line. Results: Here, we observed that DHA is specifically neuroprotective against zinc-triggered mitochondrial dysfunction, but does not directly affect Aβ neurotoxicity. CoQ10 has shown to be protective against both Aβ- and zinc-induced alterations in mitochondrial function. Conclusion: Our results indicate that DHA and CoQ10 may be useful for the prevention, treatment and management of neurodegenerative diseases such as AD.

Mitochondrial DNA sequence evolution in shorebird populations

NARCIS (Netherlands)

Wenink, P.W.

1994-01-01

This thesis describes the global molecular population structure of two shorebird species, in particular of the dunlin, Calidris alpina, by means of comparative sequence analysis of the most variable part of the mitochondrial DNA (mtDNA) genome. There are several reasons

Mitochondrial Iron Transport and Homeostasis in Plants

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Anshika eJain

2013-09-01

Full Text Available Iron (Fe is an essential nutrient for plants and although the mechanisms controlling iron uptake from the soil are relatively well understood, comparatively little is known about subcellular trafficking of iron in plant cells. Mitochondria represent a significant iron sink within cells, as iron is required for the proper functioning of respiratory chain protein complexes. Mitochondria are a site of Fe-S cluster synthesis, and possibly heme synthesis as well. Here we review recent insights into the molecular mechanisms controlling mitochondrial iron transport and homeostasis. We focus on the recent identification of a mitochondrial iron uptake transporter in rice and a possible role for metalloreductases in iron uptake by mitochondria. In addition, we highlight recent advances in mitochondrial iron homeostasis with an emphasis on the roles of frataxin and ferritin in iron trafficking and storage within mitochondria.

High-throughput respirometric assay identifies predictive toxicophore of mitochondrial injury

Energy Technology Data Exchange (ETDEWEB)

Wills, Lauren P. [MitoHealth Inc., Charleston, SC 29403 (United States); Beeson, Gyda C.; Trager, Richard E.; Lindsey, Christopher C. [Department of Drug Discovery and Biomedical Sciences, Medical University of South Carolina, Charleston, SC 29425 (United States); Beeson, Craig C. [MitoHealth Inc., Charleston, SC 29403 (United States); Peterson, Yuri K. [Department of Drug Discovery and Biomedical Sciences, Medical University of South Carolina, Charleston, SC 29425 (United States); Schnellmann, Rick G., E-mail: schnell@musc.edu [Department of Drug Discovery and Biomedical Sciences, Medical University of South Carolina, Charleston, SC 29425 (United States); Ralph H. Johnson VA Medical Center, Charleston, SC 29401 (United States)

2013-10-15

Many environmental chemicals and drugs negatively affect human health through deleterious effects on mitochondrial function. Currently there is no chemical library of mitochondrial toxicants, and no reliable methods for predicting mitochondrial toxicity. We hypothesized that discrete toxicophores defined by distinct chemical entities can identify previously unidentified mitochondrial toxicants. We used a respirometric assay to screen 1760 compounds (5 μM) from the LOPAC and ChemBridge DIVERSet libraries. Thirty-one of the assayed compounds decreased uncoupled respiration, a stress test for mitochondrial dysfunction, prior to a decrease in cell viability and reduced the oxygen consumption rate in isolated mitochondria. The mitochondrial toxicants were grouped by chemical similarity and two clusters containing four compounds each were identified. Cheminformatic analysis of one of the clusters identified previously uncharacterized mitochondrial toxicants from the ChemBridge DIVERSet. This approach will enable the identification of mitochondrial toxicants and advance the prediction of mitochondrial toxicity for both drug discovery and risk assessment. - Highlights: • Respirometric assay conducted in RPTC to create mitochondrial toxicant database. • Chemically similar mitochondrial toxicants aligned as mitochondrial toxicophores • Mitochondrial toxicophore identifies five novel mitochondrial toxicants.

High-throughput respirometric assay identifies predictive toxicophore of mitochondrial injury

International Nuclear Information System (INIS)

Wills, Lauren P.; Beeson, Gyda C.; Trager, Richard E.; Lindsey, Christopher C.; Beeson, Craig C.; Peterson, Yuri K.; Schnellmann, Rick G.

2013-01-01

Many environmental chemicals and drugs negatively affect human health through deleterious effects on mitochondrial function. Currently there is no chemical library of mitochondrial toxicants, and no reliable methods for predicting mitochondrial toxicity. We hypothesized that discrete toxicophores defined by distinct chemical entities can identify previously unidentified mitochondrial toxicants. We used a respirometric assay to screen 1760 compounds (5 μM) from the LOPAC and ChemBridge DIVERSet libraries. Thirty-one of the assayed compounds decreased uncoupled respiration, a stress test for mitochondrial dysfunction, prior to a decrease in cell viability and reduced the oxygen consumption rate in isolated mitochondria. The mitochondrial toxicants were grouped by chemical similarity and two clusters containing four compounds each were identified. Cheminformatic analysis of one of the clusters identified previously uncharacterized mitochondrial toxicants from the ChemBridge DIVERSet. This approach will enable the identification of mitochondrial toxicants and advance the prediction of mitochondrial toxicity for both drug discovery and risk assessment. - Highlights: • Respirometric assay conducted in RPTC to create mitochondrial toxicant database. • Chemically similar mitochondrial toxicants aligned as mitochondrial toxicophores • Mitochondrial toxicophore identifies five novel mitochondrial toxicants

Sequencing and analysis of the complete mitochondrial genome in Anopheles sinensis (Diptera: Culicidae).

Science.gov (United States)

Chen, Kai; Wang, Yan; Li, Xiang-Yu; Peng, Heng; Ma, Ya-Jun

2017-10-02

Anopheles sinensis (Diptera: Culicidae) is a primary vector of Plasmodium vivax and Brugia malayi in most regions of China. In addition, its phylogenetic relationship with the cryptic species of the Hyrcanus Group is complex and remains unresolved. Mitochondrial genome sequences are widely used as molecular markers for phylogenetic studies of mosquito species complexes, of which mitochondrial genome data of An. sinensis is not available. An. sinensis samples was collected from Shandong, China, and identified by molecular marker. Genomic DNA was extracted, followed by the Illumina sequencing. Two complete mitochondrial genomes were assembled and annotated using the mitochondrial genome of An. gambiae as reference. The mitochondrial genomes sequences of the 28 known Anopheles species were aligned and reconstructed phylogenetic tree by Maximum Likelihood (ML) method. The length of complete mitochondrial genomes of An. sinensis was 15,076 bp and 15,138 bp, consisting of 13 protein-coding genes, 22 transfer RNA (tRNA) genes, 2 ribosomal RNA (rRNA) genes, and an AT-rich control region. As in other insects, most mitochondrial genes are encoded on the J strand, except for ND5, ND4, ND4L, ND1, two rRNA and eight tRNA genes, which are encoded on the N strand. The bootstrap value was set as 1000 in ML analyses. The topologies restored phylogenetic affinity within subfamily Anophelinae. The ML tree showed four major clades, corresponding to the subgenera Cellia, Anopheles, Nyssorhynchus and Kerteszia of the genus Anopheles. The complete mitochondrial genomes of An. sinensis were obtained. The number, order and transcription direction of An. sinensis mitochondrial genes were the same as in other species of family Culicidae.

Complete mitochondrial genomes reveal phylogeny relationship and evolutionary history of the family Felidae.

Science.gov (United States)

Zhang, W Q; Zhang, M H

2013-09-03

Many mitochondrial DNA sequences are used to estimate phylogenetic relationships among animal taxa and perform molecular phylogenetic evolution analysis. With the continuous development of sequencing technology, numerous mitochondrial sequences have been released in public databases, especially complete mitochondrial DNA sequences. Using multiple sequences is better than using single sequences for phylogenetic analysis of animals because multiple sequences have sufficient information for evolutionary process reconstruction. Therefore, we performed phylogenetic analyses of 14 species of Felidae based on complete mitochondrial genome sequences, with Canis familiaris as an outgroup, using neighbor joining, maximum likelihood, maximum parsimony, and Bayesian inference methods. The consensus phylogenetic trees supported the monophyly of Felidae, and the family could be divided into 2 subfamilies, Felinae and Pantherinae. The genus Panthera and species tigris were also studied in detail. Meanwhile, the divergence of this family was estimated by phylogenetic analysis using the Bayesian method with a relaxed molecular clock, and the results shown were consistent with previous studies. In summary, the evolution of Felidae was reconstructed by phylogenetic analysis based on mitochondrial genome sequences. The described method may be broadly applicable for phylogenetic analyses of anima taxa.

Expression of a novel non-coding mitochondrial RNA in human proliferating cells.

Science.gov (United States)

Villegas, Jaime; Burzio, Veronica; Villota, Claudio; Landerer, Eduardo; Martinez, Ronny; Santander, Marcela; Martinez, Rodrigo; Pinto, Rodrigo; Vera, María I; Boccardo, Enrique; Villa, Luisa L; Burzio, Luis O

2007-01-01

Previously, we reported the presence in mouse cells of a mitochondrial RNA which contains an inverted repeat (IR) of 121 nucleotides (nt) covalently linked to the 5' end of the mitochondrial 16S RNA (16S mtrRNA). Here, we report the structure of an equivalent transcript of 2374 nt which is over-expressed in human proliferating cells but not in resting cells. The transcript contains a hairpin structure comprising an IR of 815 nt linked to the 5' end of the 16S mtrRNA and forming a long double-stranded structure or stem and a loop of 40 nt. The stem is resistant to RNase A and can be detected and isolated after digestion with the enzyme. This novel transcript is a non-coding RNA (ncRNA) and several evidences suggest that the transcript is synthesized in mitochondria. The expression of this transcript can be induced in resting lymphocytes stimulated with phytohaemagglutinin (PHA). Moreover, aphidicolin treatment of DU145 cells reversibly blocks proliferation and expression of the transcript. If the drug is removed, the cells re-assume proliferation and over-express the ncmtRNA. These results suggest that the expression of the ncmtRNA correlates with the replicative state of the cell and it may play a role in cell proliferation.

Molecular epidemiology of human rhinoviruses

OpenAIRE

Savolainen-Kopra, Carita

2006-01-01

The first part of this work investigates the molecular epidemiology of a human enterovirus (HEV), echovirus 30 (E-30). This project is part of a series of studies performed in our research team analyzing the molecular epidemiology of HEV-B viruses. A total of 129 virus strains had been isolated in different parts of Europe. The sequence analysis was performed in three different genomic regions: 420 nucleotides (nt) in the VP4/VP2 capsid protein coding region, the entire VP1 capsid protein cod...

Presence of a mitochondrial-type 70-kDa heat shock protein in Trichomonas vaginalis suggests a very early mitochondrial endosymbiosis in eukaryotes

Science.gov (United States)

Germot, Agnès; Philippe, Hervé; Le Guyader, Hervé

1996-01-01

Molecular phylogenetic analyses, based mainly on ribosomal RNA, show that three amitochondriate protist lineages, diplomonads, microsporidia, and trichomonads, emerge consistently at the base of the eukaryotic tree before groups having mitochondria. This suggests that these groups could have diverged before the mitochondrial endosymbiosis. Nevertheless, since all these organisms live in anaerobic environments, the absence of mitochondria might be due to secondary loss, as demonstrated for the later emerging eukaryote Entamoeba histolytica. We have now isolated from Trichomonas vaginalis a gene encoding a chaperone protein (HSP70) that in other lineages is addressed to the mitochondrial compartment. The phylogenetic reconstruction unambiguously located this HSP70 within a large set of mitochondrial sequences, itself a sister-group of α-purple bacteria. In addition, the T. vaginalis protein exhibits the GDAWV sequence signature, so far exclusively found in mitochondrial HSP70 and in proteobacterial dnaK. Thus mitochondrial endosymbiosis could have occurred earlier than previously assumed. The trichomonad double membrane-bounded organelles, the hydrogenosomes, could have evolved from mitochondria. PMID:8962101

Validation of the use of an artificial mitochondrial reporter DNA vector containing a Cytomegalovirus promoter for mitochondrial transgene expression.

Science.gov (United States)

Yamada, Yuma; Ishikawa, Takuya; Harashima, Hideyoshi

2017-08-01

Mitochondria have their own gene expression system that is independent of the nuclear system, and control cellular functions in cooperation with the nucleus. While a number of useful technologies for achieving nuclear transgene expression have been reported, only a few have focused on mitochondria. In this study, we validated the utility of an artificial mitochondrial DNA vector with a virus promoter on mitochondrial transgene expression. We designed and constructed pCMV-mtLuc (CGG) that contains a CMV promotor derived from Cytomegalovirus and an artificial mitochondrial genome with a NanoLuc (Nluc) luciferase gene that records adjustments to the mitochondrial codon system. Nluc luciferase activity measurements showed that the pCMV-mtLuc (CGG) efficiently produced the Nluc luciferase protein in human HeLa cells. Moreover, we optimized the mitochondrial transfection of pCMV-mtLuc (CGG) using a MITO-Porter system, a liposome-based carrier for mitochondrial delivery via membrane fusion. As a result, we found that transfection of pCMV-mtLuc (CGG) by MITO-Porter modified with the KALA peptide (cationic amphipathic cell-penetrating peptide) showed a high mitochondrial transgene expression. The developed mitochondrial transgene expression system represents a potentially useful tool for the fields of nanoscience and nanotechnology for controlling the intracellular microenvironment via the regulation of mitochondrial function and promises to open additional innovative research fields of study. Copyright © 2017 Elsevier Ltd. All rights reserved.

Mitochondrial Disease

OpenAIRE

Bulent Kurt; Turgut Topal

2013-01-01

Mitochondria are the major energy source of cells. Mitochondrial disease occurs due to a defect in mitochondrial energy production. A valuable energy production in mitochondria depend a healthy interconnection between nuclear and mitochondrial DNA. A mutation in nuclear or mitochondrial DNA may cause abnormalities in ATP production and single or multiple organ dysfunctions, secondarily. In this review, we summarize mitochondrial physiology, mitochondrial genetics, and clinical expression and ...

Cloning and functional analysis of human mTERFL encoding a novel mitochondrial transcription termination factor-like protein

International Nuclear Information System (INIS)

Chen Yao; Zhou Guangjin; Yu Min; He Yungang; Tang Wei; Lai Jianhua; He Jie; Liu Wanguo; Tan Deyong

2005-01-01

Serum plays an important role in the regulation of cell cycle and cell growth. To identify novel serum-inhibitory factors and study their roles in cell cycle regulation, we performed mRNA differential display analysis of U251 cells in the presence or absence of serum and cloned a novel gene encoding the human mitochondrial transcription termination factor-like protein (mTERFL). The full-length mTERFL cDNA has been isolated and the genomic structure determined. The mTERFL gene consists of three exons and encodes 385 amino acids with 52% sequence similarity to the human mitochondrial transcription termination factor (mTERF). However, mTERFL and mTERF have an opposite expression pattern in response to serum. The expression of mTERFL is dramatically inhibited by the addition of serum in serum-starved cells while the mTERF is rather induced. Northern blot analysis detected three mTERFL transcripts of 1.7, 3.2, and 3.5 kb. Besides the 3.2 kb transcript that is unique to skeletal muscle, other two transcripts express predominant in heart, liver, pancreas, and skeletal muscle. Expression of the GFP-mTERFL fusion protein in HeLa cells localized it to the mitochondria. Furthermore, ectopic expression of mTERFL suppresses cell growth and arrests cells in the G1 stage demonstrated by MTT and flow cytometry analysis. Collectively, our data suggest that mTERFL is a novel mTERF family member and a serum-inhibitory factor probably participating in the regulation of cell growth through the modulation of mitochondrial transcription

Mitochondrial oxodicarboxylate carrier deficiency is associated with mitochondrial DNA depletion and spinal muscular atrophy-like disease.

Science.gov (United States)

Boczonadi, Veronika; King, Martin S; Smith, Anthony C; Olahova, Monika; Bansagi, Boglarka; Roos, Andreas; Eyassu, Filmon; Borchers, Christoph; Ramesh, Venkateswaran; Lochmüller, Hanns; Polvikoski, Tuomo; Whittaker, Roger G; Pyle, Angela; Griffin, Helen; Taylor, Robert W; Chinnery, Patrick F; Robinson, Alan J; Kunji, Edmund R S; Horvath, Rita

2018-03-08

PurposeTo understand the role of the mitochondrial oxodicarboxylate carrier (SLC25A21) in the development of spinal muscular atrophy-like disease.MethodsWe identified a novel pathogenic variant in a patient by whole-exome sequencing. The pathogenicity of the mutation was studied by transport assays, computer modeling, followed by targeted metabolic testing and in vitro studies in human fibroblasts and neurons.ResultsThe patient carries a homozygous pathogenic variant c.695A>G; p.(Lys232Arg) in the SLC25A21 gene, encoding the mitochondrial oxodicarboxylate carrier, and developed spinal muscular atrophy and mitochondrial myopathy. Transport assays show that the mutation renders SLC25A21 dysfunctional and 2-oxoadipate cannot be imported into the mitochondrial matrix. Computer models of central metabolism predicted that impaired transport of oxodicarboxylate disrupts the pathways of lysine and tryptophan degradation, and causes accumulation of 2-oxoadipate, pipecolic acid, and quinolinic acid, which was confirmed in the patient's urine by targeted metabolomics. Exposure to 2-oxoadipate and quinolinic acid decreased the level of mitochondrial complexes in neuronal cells (SH-SY5Y) and induced apoptosis.ConclusionMitochondrial oxodicarboxylate carrier deficiency leads to mitochondrial dysfunction and the accumulation of oxoadipate and quinolinic acid, which in turn cause toxicity in spinal motor neurons leading to spinal muscular atrophy-like disease.GENETICS in MEDICINE advance online publication, 8 March 2018; doi:10.1038/gim.2017.251.

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

Science.gov (United States)

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.

The human PINK1 locus is regulated in vivo by a non-coding natural antisense RNA during modulation of mitochondrial function

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Wahlestedt Claes

2007-03-01

Full Text Available Abstract Background Mutations in the PTEN induced putative kinase 1 (PINK1 are implicated in early-onset Parkinson's disease. PINK1 is expressed abundantly in mitochondria rich tissues, such as skeletal muscle, where it plays a critical role determining mitochondrial structural integrity in Drosophila. Results Herein we characterize a novel splice variant of PINK1 (svPINK1 that is homologous to the C-terminus regulatory domain of the protein kinase. Naturally occurring non-coding antisense provides sophisticated mechanisms for diversifying genomes and we describe a human specific non-coding antisense expressed at the PINK1 locus (naPINK1. We further demonstrate that PINK1 varies in vivo when human skeletal muscle mitochondrial content is enhanced, supporting the idea that PINK1 has a physiological role in mitochondrion. The observation of concordant regulation of svPINK1 and naPINK1 during in vivo mitochondrial biogenesis was confirmed using RNAi, where selective targeting of naPINK1 results in loss of the PINK1 splice variant in neuronal cell lines. Conclusion Our data presents the first direct observation that a mammalian non-coding antisense molecule can positively influence the abundance of a cis-transcribed mRNA under physiological abundance conditions. While our analysis implies a possible human specific and dsRNA-mediated mechanism for stabilizing the expression of svPINK1, it also points to a broader genomic strategy for regulating a human disease locus and increases the complexity through which alterations in the regulation of the PINK1 locus could occur.

Metabolites from invasive pests inhibit mitochondrial complex II: A potential strategy for the treatment of human ovarian carcinoma?

Energy Technology Data Exchange (ETDEWEB)

Ferramosca, Alessandra, E-mail: alessandra.ferramosca@unisalento.it [Dipartimento di Scienze e Tecnologie Biologiche ed Ambientali, Università del Salento, Lecce (Italy); Conte, Annalea; Guerra, Flora; Felline, Serena [Dipartimento di Scienze e Tecnologie Biologiche ed Ambientali, Università del Salento, Lecce (Italy); Rimoli, Maria Grazia [Dipartimento di Farmacia, Università di Napoli Federico II, Napoli (Italy); Mollo, Ernesto [Istituto di Chimica Biomolecolare, Consiglio Nazionale delle Ricerche, Pozzuoli (Italy); Zara, Vincenzo [Dipartimento di Scienze e Tecnologie Biologiche ed Ambientali, Università del Salento, Lecce (Italy); Terlizzi, Antonio [Dipartimento di Scienze e Tecnologie Biologiche ed Ambientali, Università del Salento, Lecce (Italy); Stazione Zoologica Anton Dohrn, Napoli (Italy)

2016-05-13

The red pigment caulerpin, a secondary metabolite from the marine invasive green algae Caulerpa cylindracea can be accumulated and transferred along the trophic chain, with detrimental consequences on biodiversity and ecosystem functioning. Despite increasing research efforts to understand how caulerpin modifies fish physiology, little is known on the effects of algal metabolites on mammalian cells. Here we report for the first time the mitochondrial targeting activity of both caulerpin, and its closely related derivative caulerpinic acid, by using as experimental model rat liver mitochondria, a system in which bioenergetics mechanisms are not altered. Mitochondrial function was tested by polarographic and spectrophotometric methods. Both compounds were found to selectively inhibit respiratory complex II activity, while complexes I, III, and IV remained functional. These results led us to hypothesize that both algal metabolites could be used as antitumor agents in cell lines with defects in mitochondrial complex I. Ovarian cancer cisplatin-resistant cells are a good example of cell lines with a defective complex I function on which these molecules seem to have a toxic effect on proliferation. This provided novel insight toward the potential use of metabolites from invasive Caulerpa species for the treatment of human ovarian carcinoma cisplatin-resistant cells. -- Highlights: •Novel insight toward the potential use of the algal metabolites for the treatment of human diseases. •Caulerpin and caulerpinic acid inhibit respiratory complex II activity. •Both algal metabolites could be used as antitumor agents in ovarian cancer cisplatin-resistant cells.

Metabolites from invasive pests inhibit mitochondrial complex II: A potential strategy for the treatment of human ovarian carcinoma?

International Nuclear Information System (INIS)

Ferramosca, Alessandra; Conte, Annalea; Guerra, Flora; Felline, Serena; Rimoli, Maria Grazia; Mollo, Ernesto; Zara, Vincenzo; Terlizzi, Antonio

2016-01-01

The red pigment caulerpin, a secondary metabolite from the marine invasive green algae Caulerpa cylindracea can be accumulated and transferred along the trophic chain, with detrimental consequences on biodiversity and ecosystem functioning. Despite increasing research efforts to understand how caulerpin modifies fish physiology, little is known on the effects of algal metabolites on mammalian cells. Here we report for the first time the mitochondrial targeting activity of both caulerpin, and its closely related derivative caulerpinic acid, by using as experimental model rat liver mitochondria, a system in which bioenergetics mechanisms are not altered. Mitochondrial function was tested by polarographic and spectrophotometric methods. Both compounds were found to selectively inhibit respiratory complex II activity, while complexes I, III, and IV remained functional. These results led us to hypothesize that both algal metabolites could be used as antitumor agents in cell lines with defects in mitochondrial complex I. Ovarian cancer cisplatin-resistant cells are a good example of cell lines with a defective complex I function on which these molecules seem to have a toxic effect on proliferation. This provided novel insight toward the potential use of metabolites from invasive Caulerpa species for the treatment of human ovarian carcinoma cisplatin-resistant cells. -- Highlights: •Novel insight toward the potential use of the algal metabolites for the treatment of human diseases. •Caulerpin and caulerpinic acid inhibit respiratory complex II activity. •Both algal metabolites could be used as antitumor agents in ovarian cancer cisplatin-resistant cells.

Mitochondrial Recombination and Introgression during Speciation by Hybridization.

Science.gov (United States)

Leducq, Jean-Baptiste; Henault, Mathieu; Charron, Guillaume; Nielly-Thibault, Lou; Terrat, Yves; Fiumera, Heather L; Shapiro, B Jesse; Landry, Christian R

2017-08-01

Genome recombination is a major source of genotypic diversity and contributes to adaptation and speciation following interspecies hybridization. The contribution of recombination in these processes has been thought to be largely limited to the nuclear genome because organelles are mostly uniparentally inherited in animals and plants, which prevents recombination. Unicellular eukaryotes such as budding yeasts do, however, transmit mitochondria biparentally, suggesting that during hybridization, both parents could provide alleles that contribute to mitochondrial functions such as respiration and metabolism in hybrid populations or hybrid species. We examined the dynamics of mitochondrial genome transmission and evolution during speciation by hybridization in the natural budding yeast Saccharomyces paradoxus. Using population-scale mitochondrial genome sequencing in two endemic North American incipient species SpB and SpC and their hybrid species SpC*, we found that both parental species contributed to the hybrid mitochondrial genome through recombination. We support our findings by showing that mitochondrial recombination between parental types is frequent in experimental crosses that recreate the early step of this speciation event. In these artificial hybrids, we observed that mitochondrial genome recombination enhances phenotypic variation among diploid hybrids, suggesting that it could play a role in the phenotypic differentiation of hybrid species. Like the nuclear genome, the mitochondrial genome can, therefore, also play a role in hybrid speciation. © The Author 2017. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Codon usage and expression level of human mitochondrial 13 protein coding genes across six continents.

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Chakraborty, Supriyo; Uddin, Arif; Mazumder, Tarikul Huda; Choudhury, Monisha Nath; Malakar, Arup Kumar; Paul, Prosenjit; Halder, Binata; Deka, Himangshu; Mazumder, Gulshana Akthar; Barbhuiya, Riazul Ahmed; Barbhuiya, Masuk Ahmed; Devi, Warepam Jesmi

2017-12-02

The study of codon usage coupled with phylogenetic analysis is an important tool to understand the genetic and evolutionary relationship of a gene. The 13 protein coding genes of human mitochondria are involved in electron transport chain for the generation of energy currency (ATP). However, no work has yet been reported on the codon usage of the mitochondrial protein coding genes across six continents. To understand the patterns of codon usage in mitochondrial genes across six different continents, we used bioinformatic analyses to analyze the protein coding genes. The codon usage bias was low as revealed from high ENC value. Correlation between codon usage and GC3 suggested that all the codons ending with G/C were positively correlated with GC3 but vice versa for A/T ending codons with the exception of ND4L and ND5 genes. Neutrality plot revealed that for the genes ATP6, COI, COIII, CYB, ND4 and ND4L, natural selection might have played a major role while mutation pressure might have played a dominant role in the codon usage bias of ATP8, COII, ND1, ND2, ND3, ND5 and ND6 genes. Phylogenetic analysis indicated that evolutionary relationships in each of 13 protein coding genes of human mitochondria were different across six continents and further suggested that geographical distance was an important factor for the origin and evolution of 13 protein coding genes of human mitochondria. Copyright © 2017 Elsevier B.V. and Mitochondria Research Society. All rights reserved.

Primary structure of the human M2 mitochondrial autoantigen of primary biliary cirrhosis: Dihydrolipoamide acetyltransferase

International Nuclear Information System (INIS)

Coppel, R.L.; McNeilage, L.J.; Surh, C.D.; Van De Water, J.; Spithill, T.W.; Whittingham, S.; Gershwin, M.E.

1988-01-01

Primary biliary cirrhosis is a chronic, destructive autoimmune liver disease of humans. Patient sera are characterized by a high frequency of autoantibodies to a M r 70,000 mitochondrial antigen a component of the M2 antigen complex. The authors have identified a human cDNA clone encoding the complete amino acid sequence of this autoantigen. The predicted structure has significant similarity with the dihydrolipoamide acetyltransferase of the Escherichia coli pyruvate dehydrogenase multienzyme complex. The human sequence preserves the Glu-Thr-Asp-Lys-Ala motif of the lipoyl-binding site and has two potential binding sites. Expressed fragments of the cDNA react strongly with sera from patients with primary biliary cirrhosis but not with sera from patients with autoimmune chronic active hepatitis or sera from healthy subjects

Reconstitution of proapoptotic BAK function in liposomes reveals a dual role for mitochondrial lipids in the BAK-driven membrane permeabilization process.

Science.gov (United States)

Landeta, Olatz; Landajuela, Ane; Gil, David; Taneva, Stefka; Di Primo, Carmelo; Sot, Begoña; Valle, Mikel; Frolov, Vadim A; Basañez, Gorka

2011-03-11

BAK is a key effector of mitochondrial outer membrane permeabilization (MOMP) whose molecular mechanism of action remains to be fully dissected in intact cells, mainly due to the inherent complexity of the intracellular apoptotic machinery. Here we show that the core features of the BAK-driven MOMP pathway can be reproduced in a highly simplified in vitro system consisting of recombinant human BAK lacking the carboxyl-terminal 21 residues (BAKΔC) and tBID in combination with liposomes bearing an appropriate lipid environment. Using this minimalist reconstituted system we established that tBID suffices to trigger BAKΔC membrane insertion, oligomerization, and pore formation. Furthermore, we demonstrate that tBID-activated BAKΔC permeabilizes the membrane by forming structurally dynamic pores rather than a large proteinaceous channel of fixed size. We also identified two distinct roles played by mitochondrial lipids along the molecular pathway of BAKΔC-induced membrane permeabilization. First, using several independent approaches, we showed that cardiolipin directly interacts with BAKΔC, leading to a localized structural rearrangement in the protein that "primes" BAKΔC for interaction with tBID. Second, we provide evidence that selected curvature-inducing lipids present in mitochondrial membranes specifically modulate the energetic expenditure required to create the BAKΔC pore. Collectively, our results support the notion that BAK functions as a direct effector of MOMP akin to BAX and also adds significantly to the growing evidence indicating that mitochondrial membrane lipids are actively implicated in BCL-2 protein family function.

Transcriptional and phylogenetic analysis of five complete ambystomatid salamander mitochondrial genomes.

Science.gov (United States)

Samuels, Amy K; Weisrock, David W; Smith, Jeramiah J; France, Katherine J; Walker, John A; Putta, Srikrishna; Voss, S Randal

2005-04-11

salamander complex species also produced robustly supported trees. The D-loop, used in previous molecular phylogenetic studies of the complex, was found to contain a relatively low level of variation and we identified mitochondrial regions with higher rates of molecular evolution that are more useful in resolving relationships among species. Our results show the benefit of using complete genome mitochondrial information in studies of recently and rapidly diverged taxa.

Mitochondrial Dysfunction and Oxidative Stress in Asthma: Implications for Mitochondria-Targeted Antioxidant Therapeutics

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P. Hemachandra Reddy

2011-02-01

Full Text Available Asthma is a complex, inflammatory disorder characterized by airflow obstruction of variable degrees, bronchial hyper-responsiveness, and airway inflammation. Asthma is caused by environmental factors and a combination of genetic and environmental stimuli. Genetic studies have revealed that multiple loci are involved in the etiology of asthma. Recent cellular, molecular, and animal-model studies have revealed several cellular events that are involved in the progression of asthma, including: increased Th2 cytokines leading to the recruitment of inflammatory cells to the airway, and an increase in the production of reactive oxygen species and mitochondrial dysfunction in the activated inflammatory cells, leading to tissue injury in the bronchial epithelium. Further, aging and animal model studies have revealed that mitochondrial dysfunction and oxidative stress are involved and play a large role in asthma. Recent studies using experimental allergic asthmatic mouse models and peripheral cells and tissues from asthmatic humans have revealed antioxidants as promising treatments for people with asthma. This article summarizes the latest research findings on the involvement of inflammatory changes, and mitochondrial dysfunction/oxidative stress in the development and progression of asthma. This article also addresses the relationship between aging and age-related immunity in triggering asthma, the antioxidant therapeutic strategies in treating people with asthma.

Mitochondrial DNA depletion syndrome presenting with ataxia and ...

African Journals Online (AJOL)

The patient presented to Cairo University Pediatric Hospital with the clinical suspicion of mitochondrial encephalomyopathy. Histochemical and biochemical studies of the respiratory chain complexes were performed on the muscle biopsy specimen from the patient. Molecular diagnosis was done by quantitative radioactive ...

Mitochondrial Respiration Is Reduced in Atherosclerosis, Promoting Necrotic Core Formation and Reducing Relative Fibrous Cap Thickness.

Science.gov (United States)

Yu, Emma P K; Reinhold, Johannes; Yu, Haixiang; Starks, Lakshi; Uryga, Anna K; Foote, Kirsty; Finigan, Alison; Figg, Nichola; Pung, Yuh-Fen; Logan, Angela; Murphy, Michael P; Bennett, Martin

2017-12-01

Mitochondrial DNA (mtDNA) damage is present in murine and human atherosclerotic plaques. However, whether endogenous levels of mtDNA damage are sufficient to cause mitochondrial dysfunction and whether decreasing mtDNA damage and improving mitochondrial respiration affects plaque burden or composition are unclear. We examined mitochondrial respiration in human atherosclerotic plaques and whether augmenting mitochondrial respiration affects atherogenesis. Human atherosclerotic plaques showed marked mitochondrial dysfunction, manifested as reduced mtDNA copy number and oxygen consumption rate in fibrous cap and core regions. Vascular smooth muscle cells derived from plaques showed impaired mitochondrial respiration, reduced complex I expression, and increased mitophagy, which was induced by oxidized low-density lipoprotein. Apolipoprotein E-deficient (ApoE -/- ) mice showed decreased mtDNA integrity and mitochondrial respiration, associated with increased mitochondrial reactive oxygen species. To determine whether alleviating mtDNA damage and increasing mitochondrial respiration affects atherogenesis, we studied ApoE -/- mice overexpressing the mitochondrial helicase Twinkle (Tw + /ApoE -/- ). Tw + /ApoE -/- mice showed increased mtDNA integrity, copy number, respiratory complex abundance, and respiration. Tw + /ApoE -/- mice had decreased necrotic core and increased fibrous cap areas, and Tw + /ApoE -/- bone marrow transplantation also reduced core areas. Twinkle increased vascular smooth muscle cell mtDNA integrity and respiration. Twinkle also promoted vascular smooth muscle cell proliferation and protected both vascular smooth muscle cells and macrophages from oxidative stress-induced apoptosis. Endogenous mtDNA damage in mouse and human atherosclerosis is associated with significantly reduced mitochondrial respiration. Reducing mtDNA damage and increasing mitochondrial respiration decrease necrotic core and increase fibrous cap areas independently of changes in

The mitochondrial genome of Cethosia biblis (Drury) (Lepidoptera: Nymphalidae).

Science.gov (United States)

Xin, Tianrong; Li, Lei; Yao, Chengyi; Wang, Yayu; Zou, Zhiwen; Wang, Jing; Xia, Bin

2016-07-01

We present the complete mitogenome of Cethosia biblis (Drury) (Lepidoptera: Nymphalidae) in this article. The mitogenome was a circle molecular consisting of 15,286 nucleotides, 37 genes, and an A + T-rich region. The order of 37 genes was typical of insect mitochondrial DNA sequences described to date. The overall base composition of the genome is A (37.41%), T (42.80%), C (11.87%), and G (7.91%) with an A + T-rich hallmark as that of other invertebrate mitochondrial genomes. The start codon was mainly ATA in most of the mitochondrial protein-coding genes such as ND2, COI, ATP8, ND3, ND5, ND4, ND6, and ND1, but COII, ATP6, COIII, ND4L, and Cob genes employing ATG. The stop codon was TAA in all the protein-coding genes. The A + T region is located between 12S rRNA and tRNA(M)(et). The phylogenetic relationships of Lepidoptera species were constructed based on the nucleotides sequences of 13 PCGs of mitogenomes using the neighbor-joining method. The molecular-based phylogeny supported the traditional morphological classification on relationships within Lepidoptera species.

Molecular Strategies for Targeting Antioxidants to Mitochondria: Therapeutic Implications

Science.gov (United States)

2015-01-01

Abstract Mitochondrial function and specifically its implication in cellular redox/oxidative balance is fundamental in controlling the life and death of cells, and has been implicated in a wide range of human pathologies. In this context, mitochondrial therapeutics, particularly those involving mitochondria-targeted antioxidants, have attracted increasing interest as potentially effective therapies for several human diseases. For the past 10 years, great progress has been made in the development and functional testing of molecules that specifically target mitochondria, and there has been special focus on compounds with antioxidant properties. In this review, we will discuss several such strategies, including molecules conjugated with lipophilic cations (e.g., triphenylphosphonium) or rhodamine, conjugates of plant alkaloids, amino-acid- and peptide-based compounds, and liposomes. This area has several major challenges that need to be confronted. Apart from antioxidants and other redox active molecules, current research aims at developing compounds that are capable of modulating other mitochondria-controlled processes, such as apoptosis and autophagy. Multiple chemically different molecular strategies have been developed as delivery tools that offer broad opportunities for mitochondrial manipulation. Additional studies, and particularly in vivo approaches under physiologically relevant conditions, are necessary to confirm the clinical usefulness of these molecules. Antioxid. Redox Signal. 22, 686–729. PMID:25546574

Complete mitochondrial genome sequences from five Eimeria species (Apicomplexa; Coccidia; Eimeriidae) infecting domestic turkeys.

Science.gov (United States)

Ogedengbe, Mosun E; El-Sherry, Shiem; Whale, Julia; Barta, John R

2014-07-17

Clinical and subclinical coccidiosis is cosmopolitan and inflicts significant losses to the poultry industry globally. Seven named Eimeria species are responsible for coccidiosis in turkeys: Eimeria dispersa; Eimeria meleagrimitis; Eimeria gallopavonis; Eimeria meleagridis; Eimeria adenoeides; Eimeria innocua; and, Eimeria subrotunda. Although attempts have been made to characterize these parasites molecularly at the nuclear 18S rDNA and ITS loci, the maternally-derived and mitotically replicating mitochondrial genome may be more suited for species level molecular work; however, only limited sequence data are available for Eimeria spp. infecting turkeys. The purpose of this study was to sequence and annotate the complete mitochondrial genomes from 5 Eimeria species that commonly infect the domestic turkey (Meleagris gallopavo). Six single-oocyst derived cultures of five Eimeria species infecting turkeys were PCR-amplified and sequenced completely prior to detailed annotation. Resulting sequences were aligned and used in phylogenetic analyses (BI, ML, and MP) that included complete mitochondrial genomes from 16 Eimeria species or concatenated CDS sequences from each genome. Complete mitochondrial genome sequences were obtained for Eimeria adenoeides Guelph, 6211 bp; Eimeria dispersa Briston, 6238 bp; Eimeria meleagridis USAR97-01, 6212 bp; Eimeria meleagrimitis USMN08-01, 6165 bp; Eimeria gallopavonis Weybridge, 6215 bp; and Eimeria gallopavonis USKS06-01, 6215 bp). The order, orientation and CDS lengths of the three protein coding genes (COI, COIII and CytB) as well as rDNA fragments encoding ribosomal large and small subunit rRNA were conserved among all sequences. Pairwise sequence identities between species ranged from 88.1% to 98.2%; sequence variability was concentrated within CDS or between rDNA fragments (where indels were common). No phylogenetic reconstruction supported monophyly of Eimeria species infecting turkeys; Eimeria dispersa may have arisen

A bumpy ride on the diagnostic bench of massive parallel sequencing, the case of the mitochondrial genome.

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Kim Vancampenhout

Full Text Available The advent of massive parallel sequencing (MPS has revolutionized the field of human molecular genetics, including the diagnostic study of mitochondrial (mt DNA dysfunction. The analysis of the complete mitochondrial genome using MPS platforms is now common and will soon outrun conventional sequencing. However, the development of a robust and reliable protocol is rather challenging. A previous pilot study for the re-sequencing of human mtDNA revealed an uneven coverage, affecting predominantly part of the plus strand. In an attempt to address this problem, we undertook a comparative study of standard and modified protocols for the Ion Torrent PGM system. We could not improve strand representation by altering the recommended shearing methodology of the standard workflow or omitting the DNA polymerase amplification step from the library construction process. However, we were able to associate coverage bias of the plus strand with a specific sequence motif. Additionally, we compared coverage and variant calling across technologies. The same samples were also sequenced on a MiSeq device which showed that coverage and heteroplasmic variant calling were much improved.

Lack of mitochondrial MutS homolog 1 in Toxoplasma gondii disrupts maintenance and fidelity of mitochondrial DNA and reveals metabolic plasticity.

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Tamila Garbuz

Full Text Available The importance of maintaining the fidelity of the mitochondrial genome is underscored by the presence of various repair pathways within this organelle. Presumably, the repair of mitochondrial DNA would be of particular importance in organisms that possess only a single mitochondrion, like the human pathogens Plasmodium falciparum and Toxoplasma gondii. Understanding the machinery that maintains mitochondrial DNA in these parasites is of particular relevance, as mitochondrial function is a validated and effective target for anti-parasitic drugs. We previously determined that the Toxoplasma MutS homolog TgMSH1 localizes to the mitochondrion. MutS homologs are key components of the nuclear mismatch repair system in mammalian cells, and both yeast and plants possess MutS homologs that localize to the mitochondria where they regulate DNA stability. Here we show that the lack of TgMSH1 results in accumulation of single nucleotide variations in mitochondrial DNA and a reduction in mitochondrial DNA content. Additionally, parasites lacking TgMSH1 function can survive treatment with the cytochrome b inhibitor atovaquone. While the Tgmsh1 knockout strain has several missense mutations in cytochrome b, none affect amino acids known to be determinants of atovaquone sensitivity and atovaquone is still able to inhibit electron transport in the Tgmsh1 mutants. Furthermore, culture of Tgmsh1 mutant in the presence atovaquone leads to parasites with enhanced atovaquone resistance and complete shutdown of respiration. Thus, parasites lacking TgMSH1 overcome the disruption of mitochondrial DNA by adapting their physiology allowing them to forgo the need for oxidative phosphorylation. Consistent with this idea, the Tgmsh1 mutant is resistant to mitochondrial inhibitors with diverse targets and exhibits reduced ability to grow in the absence of glucose. This work shows TgMSH1 as critical for the maintenance and fidelity of the mitochondrial DNA in Toxoplasma

Mitochondrial Genome Sequences and Structures Aid in the Resolution of Piroplasmida phylogeny

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Marr, Henry S.; Tarigo, Jaime L.; Cohn, Leah A.; Bird, David M.; Scholl, Elizabeth H.; Levy, Michael G.; Wiegmann, Brian M.; Birkenheuer, Adam J.

2016-01-01

The taxonomy of the order Piroplasmida, which includes a number of clinically and economically relevant organisms, is a hotly debated topic amongst parasitologists. Three genera (Babesia, Theileria, and Cytauxzoon) are recognized based on parasite life cycle characteristics, but molecular phylogenetic analyses of 18S sequences have suggested the presence of five or more distinct Piroplasmida lineages. Despite these important advancements, a few studies have been unable to define the taxonomic relationships of some organisms (e.g. C. felis and T. equi) with respect to other Piroplasmida. Additional evidence from mitochondrial genome sequences and synteny should aid in the inference of Piroplasmida phylogeny and resolution of taxonomic uncertainties. In this study, we have amplified, sequenced, and annotated seven previously uncharacterized mitochondrial genomes (Babesia canis, Babesia vogeli, Babesia rossi, Babesia sp. Coco, Babesia conradae, Babesia microti-like sp., and Cytauxzoon felis) and identified additional ribosomal fragments in ten previously characterized mitochondrial genomes. Phylogenetic analysis of concatenated mitochondrial and 18S sequences as well as cox1 amino acid sequence identified five distinct Piroplasmida groups, each of which possesses a unique mitochondrial genome structure. Specifically, our results confirm the existence of four previously identified clades (B. microti group, Babesia sensu stricto, Theileria equi, and a Babesia sensu latu group that includes B. conradae) while supporting the integration of Theileria and Cytauxzoon species into a single fifth taxon. Although known biological characteristics of Piroplasmida corroborate the proposed phylogeny, more investigation into parasite life cycles is warranted to further understand the evolution of the Piroplasmida. Our results provide an evolutionary framework for comparative biology of these important animal and human pathogens and help focus renewed efforts toward understanding the

Mitochondrial Genome Sequences and Structures Aid in the Resolution of Piroplasmida phylogeny.

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Megan E Schreeg

Full Text Available The taxonomy of the order Piroplasmida, which includes a number of clinically and economically relevant organisms, is a hotly debated topic amongst parasitologists. Three genera (Babesia, Theileria, and Cytauxzoon are recognized based on parasite life cycle characteristics, but molecular phylogenetic analyses of 18S sequences have suggested the presence of five or more distinct Piroplasmida lineages. Despite these important advancements, a few studies have been unable to define the taxonomic relationships of some organisms (e.g. C. felis and T. equi with respect to other Piroplasmida. Additional evidence from mitochondrial genome sequences and synteny should aid in the inference of Piroplasmida phylogeny and resolution of taxonomic uncertainties. In this study, we have amplified, sequenced, and annotated seven previously uncharacterized mitochondrial genomes (Babesia canis, Babesia vogeli, Babesia rossi, Babesia sp. Coco, Babesia conradae, Babesia microti-like sp., and Cytauxzoon felis and identified additional ribosomal fragments in ten previously characterized mitochondrial genomes. Phylogenetic analysis of concatenated mitochondrial and 18S sequences as well as cox1 amino acid sequence identified five distinct Piroplasmida groups, each of which possesses a unique mitochondrial genome structure. Specifically, our results confirm the existence of four previously identified clades (B. microti group, Babesia sensu stricto, Theileria equi, and a Babesia sensu latu group that includes B. conradae while supporting the integration of Theileria and Cytauxzoon species into a single fifth taxon. Although known biological characteristics of Piroplasmida corroborate the proposed phylogeny, more investigation into parasite life cycles is warranted to further understand the evolution of the Piroplasmida. Our results provide an evolutionary framework for comparative biology of these important animal and human pathogens and help focus renewed efforts toward

Caenorhabditis elegans as a Model System for Studying Drug Induced Mitochondrial Toxicity.

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Richard de Boer

Full Text Available Today HIV-1 infection is recognized as a chronic disease with obligatory lifelong treatment to keep viral titers below detectable levels. The continuous intake of antiretroviral drugs however, leads to severe and even life-threatening side effects, supposedly by the deleterious impact of nucleoside-analogue type compounds on the functioning of the mitochondrial DNA polymerase. For detailed investigation of the yet partially understood underlying mechanisms, the availability of a versatile model system is crucial. We therefore set out to develop the use of Caenorhabditis elegans to study drug induced mitochondrial toxicity. Using a combination of molecular-biological and functional assays, combined with a quantitative analysis of mitochondrial network morphology, we conclude that anti-retroviral drugs with similar working mechanisms can be classified into distinct groups based on their effects on mitochondrial morphology and biochemistry. Additionally we show that mitochondrial toxicity of antiretroviral drugs cannot be exclusively attributed to interference with the mitochondrial DNA polymerase.

Association between mitochondrial DNA variations and Alzheimer's Disease in the ADNI cohort

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Lakatos, Anita; Derbeneva, Olga; Younes, Danny; Keator, David; Bakken, Trygve; Lvova, Maria; Brandon, Marty; Guffanti, Guia; Reglodi, Dora; Saykin, Andrew; Weiner, Michael; Macciardi, Fabio; Schork, Nicholas; Wallace, Douglas C.; Potkin, Steven G.

2010-01-01

Despite the central role of amyloid deposition in the development of Alzheimer's disease (AD), the pathogenesis of AD still remains elusive at the molecular level. Increasing evidence suggests that compromised mitochondrial function contributes to the aging process and thus may increase the risk of AD. Dysfunctional mitochondria contribute to reactive oxygen species (ROS) which can lead to extensive macromolecule oxidative damage and the progression of amyloid pathology. Oxidative stress and amyloid toxicity leave neurons chemically vulnerable. Because the brain relies on aerobic metabolism, it is apparent that mitochondria are critical for the cerebral function. Mitochondrial DNA sequence-changes could shift cell dynamics and facilitate neuronal vulnerability. Therefore we postulated that mitochondrial DNA sequence polymorphisms may increase the risk of AD. We evaluated the role of mitochondrial haplogroups derived from 138 mitochondrial polymorphisms in 358 Caucasian ADNI subjects. Our results indicate that the mitochondrial haplogroup UK may confer genetic susceptibility to AD independently of the APOE4 allele. PMID:20538375

The NDUFB6 subunit of the mitochondrial respiratory chain complex I is required for electron transfer activity: A proof of principle study on stable and controlled RNA interference in human cell lines

International Nuclear Information System (INIS)

Loublier, Sandrine; Bayot, Aurelien; Rak, Malgorzata; El-Khoury, Riyad; Benit, Paule; Rustin, Pierre

2011-01-01

Highlights: → NDUFB6 is required for activity of mitochondrial complex I in human cell lines. → Lentivirus based RNA interference results in frequent off target insertions. → Flp-In recombinase mediated miRNA insertion allows gene-specific extinction. -- Abstract: Molecular bases of inherited deficiencies of mitochondrial respiratory chain complex I are still unknown in a high proportion of patients. Among 45 subunits making up this large complex, more than half has unknown function(s). Understanding the function of these subunits would contribute to our knowledge on mitochondrial physiology but might also reveal that some of these subunits are not required for the catalytic activity of the complex. A direct consequence of this finding would be the reduction of the number of candidate genes to be sequenced in patients with decreased complex I activity. In this study, we tested two different methods to stably extinct complex I subunits in cultured cells. We first found that lentivirus-mediated shRNA expression frequently resulted in the unpredicted extinction of additional gene(s) beside targeted ones. This can be ascribed to uncontrolled genetic material insertions in the genome of the host cell. This approach thus appeared inappropriate to study unknown functions of a gene. Next, we found it possible to specifically extinct a CI subunit gene by direct insertion of a miR targeting CI subunits in a Flp site (HEK293 Flp-In cells). By using this strategy we unambiguously demonstrated that the NDUFB6 subunit is required for complex I activity, and defined conditions suitable to undertake a systematic and stable extinction of the different supernumerary subunits in human cells.

The NDUFB6 subunit of the mitochondrial respiratory chain complex I is required for electron transfer activity: A proof of principle study on stable and controlled RNA interference in human cell lines

Energy Technology Data Exchange (ETDEWEB)

Loublier, Sandrine; Bayot, Aurelien; Rak, Malgorzata; El-Khoury, Riyad; Benit, Paule [Inserm U676, Hopital Robert Debre, F-75019 Paris (France); Universite Paris 7, Faculte de medecine Denis Diderot, IFR02 Paris (France); Rustin, Pierre, E-mail: pierre.rustin@inserm.fr [Inserm U676, Hopital Robert Debre, F-75019 Paris (France); Universite Paris 7, Faculte de medecine Denis Diderot, IFR02 Paris (France)

2011-10-22

Highlights: {yields} NDUFB6 is required for activity of mitochondrial complex I in human cell lines. {yields} Lentivirus based RNA interference results in frequent off target insertions. {yields} Flp-In recombinase mediated miRNA insertion allows gene-specific extinction. -- Abstract: Molecular bases of inherited deficiencies of mitochondrial respiratory chain complex I are still unknown in a high proportion of patients. Among 45 subunits making up this large complex, more than half has unknown function(s). Understanding the function of these subunits would contribute to our knowledge on mitochondrial physiology but might also reveal that some of these subunits are not required for the catalytic activity of the complex. A direct consequence of this finding would be the reduction of the number of candidate genes to be sequenced in patients with decreased complex I activity. In this study, we tested two different methods to stably extinct complex I subunits in cultured cells. We first found that lentivirus-mediated shRNA expression frequently resulted in the unpredicted extinction of additional gene(s) beside targeted ones. This can be ascribed to uncontrolled genetic material insertions in the genome of the host cell. This approach thus appeared inappropriate to study unknown functions of a gene. Next, we found it possible to specifically extinct a CI subunit gene by direct insertion of a miR targeting CI subunits in a Flp site (HEK293 Flp-In cells). By using this strategy we unambiguously demonstrated that the NDUFB6 subunit is required for complex I activity, and defined conditions suitable to undertake a systematic and stable extinction of the different supernumerary subunits in human cells.

Fidelity and Mutational Spectrum of Pfu DNA Polymerase on a Human Mitochondrial DNA Sequence

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André, Paulo; Kim, Andrea; Khrapko, Konstantin; Thilly, William G.

1997-01-01

The study of rare genetic changes in human tissues requires specialized techniques. Point mutations at fractions at or below 10−6 must be observed to discover even the most prominent features of the point mutational spectrum. PCR permits the increase in number of mutant copies but does so at the expense of creating many additional mutations or “PCR noise”. Thus, each DNA sequence studied must be characterized with regard to the DNA polymerase and conditions used to avoid interpreting a PCR-generated mutation as one arising in human tissue. The thermostable DNA polymerase derived from Pyrococcus furiosus designated Pfu has the highest fidelity of any DNA thermostable polymerase studied to date, and this property recommends it for analyses of tissue mutational spectra. Here, we apply constant denaturant capillary electrophoresis (CDCE) to separate and isolate the products of DNA amplification. This new strategy permitted direct enumeration and identification of point mutations created by Pfu DNA polymerase in a 96-bp low melting domain of a human mitochondrial sequence despite the very low mutant fractions generated in the PCR process. This sequence, containing part of the tRNA glycine and NADH dehydrogenase subunit 3 genes, is the target of our studies of mitochondrial mutagenesis in human cells and tissues. Incorrectly synthesized sequences were separated from the wild type as mutant/wild-type heteroduplexes by sequential enrichment on CDCE. An artificially constructed mutant was used as an internal standard to permit calculation of the mutant fraction. Our study found that the average error rate (mutations per base pair duplication) of Pfu was 6.5 × 10−7, and five of its more frequent mutations (hot spots) consisted of three transversions (GC → TA, AT → TA, and AT → CG), one transition (AT → GC), and one 1-bp deletion (in an AAAAAA sequence). To achieve an even higher sensitivity, the amount of Pfu-induced mutants must be

Fidelity and mutational spectrum of Pfu DNA polymerase on a human mitochondrial DNA sequence.

Science.gov (United States)

André, P; Kim, A; Khrapko, K; Thilly, W G

1997-08-01

The study of rare genetic changes in human tissues requires specialized techniques. Point mutations at fractions at or below 10(-6) must be observed to discover even the most prominent features of the point mutational spectrum. PCR permits the increase in number of mutant copies but does so at the expense of creating many additional mutations or "PCR noise". Thus, each DNA sequence studied must be characterized with regard to the DNA polymerase and conditions used to avoid interpreting a PCR-generated mutation as one arising in human tissue. The thermostable DNA polymerase derived from Pyrococcus furiosus designated Pfu has the highest fidelity of any DNA thermostable polymerase studied to date, and this property recommends it for analyses of tissue mutational spectra. Here, we apply constant denaturant capillary electrophoresis (CDCE) to separate and isolate the products of DNA amplification. This new strategy permitted direct enumeration and identification of point mutations created by Pfu DNA polymerase in a 96-bp low melting domain of a human mitochondrial sequence despite the very low mutant fractions generated in the PCR process. This sequence, containing part of the tRNA glycine and NADH dehydrogenase subunit 3 genes, is the target of our studies of mitochondrial mutagenesis in human cells and tissues. Incorrectly synthesized sequences were separated from the wild type as mutant/wild-type heteroduplexes by sequential enrichment on CDCE. An artificially constructed mutant was used as an internal standard to permit calculation of the mutant fraction. Our study found that the average error rate (mutations per base pair duplication) of Pfu was 6.5 x 10(-7), and five of its more frequent mutations (hot spots) consisted of three transversions (GC-->TA, AT-->TA, and AT-->CG), one transition (AT-->GC), and one 1-bp deletion (in an AAAAAA sequence). To achieve an even higher sensitivity, the amount of Pfu-induced mutants must be reduced.

Mitochondrial deficiency: a double-edged sword for ageing and neurodegeneration

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Daniele eBano

2012-11-01

Full Text Available For decades, ageing was considered the inevitable result of the accumulation of damaged macromolecules due to environmental factors and intrinsic processes. Our current knowledge clearly supports that ageing is a complex biological process influenced by multiple evolutionary conserved molecular pathways. With the advanced age, loss of cellular homeostasis severely affects the structure and function of various tissues, especially those highly sensitive to stressful conditions like the central nervous system. In this regard, the age-related regression of neural circuits and the consequent poor neuronal plasticity have been associated with metabolic dysfunctions, in which the decline of mitochondrial activity significantly contributes. Interestingly, while mitochondrial lesions promote the onset of degenerative disorders, mild mitochondrial manipulations delay some of the age-related phenotypes and, more importantly, increase the lifespan of organisms ranging from invertebrates to mammals. Here, we survey the insulin/IGF-1 and the TOR signaling pathways and review how these two important longevity determinants regulate mitochondrial activity. Furthermore, we discuss the contribution of slight mitochondrial dysfunction in the engagement of pro-longevity processes and the opposite role of strong mitochondrial dysfunction in neurodegeneration.

PINK1/Parkin-Dependent Mitochondrial Surveillance: From Pleiotropy to Parkinson's Disease

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Olga Corti

2017-05-01

Full Text Available Parkinson's disease (PD is one of the most frequent neurodegenerative disease caused by the preferential, progressive degeneration of the dopaminergic (DA neurons of the substantia nigra (SN pars compacta. PD is characterized by a multifaceted pathological process involving protein misfolding, mitochondrial dysfunction, neuroinflammation and metabolism deregulation. The molecular mechanisms governing the complex interplay between the different facets of this process are still unknown. PARK2/Parkin and PARK6/PINK1, two genes responsible for familial forms of PD, act as a ubiquitous core signaling pathway, coupling mitochondrial stress to mitochondrial surveillance, by regulating mitochondrial dynamics, the removal of damaged mitochondrial components by mitochondria-derived vesicles, mitophagy, and mitochondrial biogenesis. Over the last decade, PINK1/Parkin-dependent mitochondrial quality control emerged as a pleiotropic regulatory pathway. Loss of its function impinges on a number of physiological processes suspected to contribute to PD pathogenesis. Its role in the regulation of innate immunity and inflammatory processes stands out, providing compelling support to the contribution of non-cell-autonomous immune mechanisms in PD. In this review, we illustrate the central role of this multifunctional pathway at the crossroads between mitochondrial stress, neuroinflammation and metabolism. We discuss how its dysfunction may contribute to PD pathogenesis and pinpoint major unresolved questions in the field.

Sleep disorders associated with primary mitochondrial diseases.

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Ramezani, Ryan J; Stacpoole, Peter W

2014-11-15

Primary mitochondrial diseases are caused by heritable or spontaneous mutations in nuclear DNA or mitochondrial DNA. Such pathological mutations are relatively common in humans and may lead to neurological and neuromuscular complication that could compromise normal sleep behavior. To gain insight into the potential impact of primary mitochondrial disease and sleep pathology, we reviewed the relevant English language literature in which abnormal sleep was reported in association with a mitochondrial disease. We examined publication reported in Web of Science and PubMed from February 1976 through January 2014, and identified 54 patients with a proven or suspected primary mitochondrial disorder who were evaluated for sleep disturbances. Both nuclear DNA and mitochondrial DNA mutations were associated with abnormal sleep patterns. Most subjects who underwent polysomnography had central sleep apnea, and only 5 patients had obstructive sleep apnea. Twenty-four patients showed decreased ventilatory drive in response to hypoxia and/ or hyperapnea that was not considered due to weakness of the intrinsic muscles of respiration. Sleep pathology may be an underreported complication of primary mitochondrial diseases. The probable underlying mechanism is cellular energy failure causing both central neurological and peripheral neuromuscular degenerative changes that commonly present as central sleep apnea and poor ventilatory response to hyperapnea. Increased recognition of the genetics and clinical manifestations of mitochondrial diseases by sleep researchers and clinicians is important in the evaluation and treatment of all patients with sleep disturbances. Prospective population-based studies are required to determine the true prevalence of mitochondrial energy failure in subjects with sleep disorders, and conversely, of individuals with primary mitochondrial diseases and sleep pathology. © 2014 American Academy of Sleep Medicine.

The Relationship Between Transcript Expression Levels of Nuclear Encoded (TFAM, NRF1 and Mitochondrial Encoded (MT-CO1 Genes in Single Human Oocytes During Oocyte Maturation

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Ghaffari Novin M.

2015-06-01

Full Text Available In some cases of infertility in women, human oocytes fail to mature when they reach the metaphase II (MII stage. Mitochondria plays an important role in oocyte maturation. A large number of mitochondrial DNA (mtDNA, copied in oocytes, is essential for providing adenosine triphosphate (ATP during oocyte maturation. The purpose of this study was to identify the relationship between transcript expression levels of the mitochondrial encoded gene (MT-CO1 and two nuclear encoded genes, nuclear respiratory factor 1 (NRF1 and mitochondrial transcription factor A (TFAM in various stages of human oocyte maturation. Nine consenting patients, age 21-35 years old, with male factors were selected for ovarian stimulation and intracytoplasmic sperm injection (ICSI procedures. mRNA levels of mitochondrial- related genes were performed by singlecell TaqMan® quantitative real-time polymerase chain reaction (qRT-PCR. There was no significant relationship between the relative expression levels in germinal vesicle (GV stage oocytes (p = 0.62. On the contrary, a significant relationship was seen between the relative expression levels of TFAM and NRF1 and the MT-CO1 genes at the stages of metaphase I (MI and MII (p = 0.03 and p = 0.002. A relationship exists between the transcript expression levels of TFAM and NRF1, and MT-CO1 genes in various stages of human oocyte maturation.

MITOCHONDRIAL BKCa CHANNEL

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Enrique eBalderas

2015-03-01

Full Text Available Since its discovery in a glioma cell line 15 years ago, mitochondrial BKCa channel (mitoBKCa has been studied in brain cells and cardiomyocytes sharing general biophysical properties such as high K+ conductance (~300 pS, voltage-dependency and Ca2+-sensitivity. Main advances in deciphering the molecular composition of mitoBKCa have included establishing that it is encoded by the Kcnma1 gene, that a C-terminal splice insert confers mitoBKCa ability to be targeted to cardiac mitochondria, and evidence for its potential coassembly with β subunits. Notoriously, β1 subunit directly interacts with cytochrome c oxidase and mitoBKCa can be modulated by substrates of the respiratory chain. mitoBKCa channel has a central role in protecting the heart from ischemia, where pharmacological activation of the channel impacts the generation of reactive oxygen species and mitochondrial Ca2+ preventing cell death likely by impeding uncontrolled opening of the mitochondrial transition pore. Supporting this view, inhibition of mitoBKCa with Iberiotoxin, enhances cytochrome c release from glioma mitochondria. Many tantalizing questions remain. Some of them are: how is mitoBKCa coupled to the respiratory chain? Does mitoBKCa play non-conduction roles in mitochondria physiology? Which are the functional partners of mitoBKCa? What are the roles of mitoBKCa in other cell types? Answers to these questions are essential to define the impact of mitoBKCa channel in mitochondria biology and disease.

Molecular mechanisms of celery seed extract induced apoptosis via s phase cell cycle arrest in the BGC-823 human stomach cancer cell line.

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Gao, Lin-Lin; Feng, Lei; Yao, Shu-Tong; Jiao, Peng; Qin, Shu-Cun; Zhang, Wei; Zhang, Ya-Bin; Li, Fu-Rong

2011-01-01

Mechanisms of apoptosis in tumor cells is an important field of tumor therapy and cancer molecular biology. Loss of cell cycle control, leading to uncontrolled proliferation, is common in cancer. Therefore, the identification of potent and selective cyclin dependent kinase inhibitors is a priority for anti-cancer drug discovery. There are at least two major apoptotic pathways, initiated by caspase-8 and caspase-9, respectively, which can activate caspase cascades. Apoptosis triggered by activation of the mitochondrial-dependent caspase pathway represents the main programmed cell death mechanism. This is activated by various intracellular stresses that induce permeabilization of the mitochondrial membrane. Anti-tumor effects of celery seed extract (CSE) and related mechanisms regarding apoptosis were here investigated in human gastric cancer BGC-823 cells. CSE was produced by supercritical fluid extraction. Cell viability was analyzed by 3-(4,5-dimethylthiazol-2-yl)- 2,5-diphenyl-tetrazolium bromide (MTT) assay and apoptosis by flow cytometry using Annexin/PI staining and DAPI staining and a laser scanning confocal microscope (LSCM). Cell cycling was evaluated using PI staining with flow cytometry and expression of cell cycle and apoptosis-related proteins cyclin A, CDK2, bcl-2 and bax was assessed by immunohistochemical staining. CSE had an anti-proliferation effect on human gastric cancer BGC-823 cells in a dose- and time-dependent manner. After treatment, the apoptotic rate significantly increased, with morphological changes typical of apoptosis observed with LSCM by DAPI staining. Cell cycle and apoptosis related proteins, such as cyclin A, CDK2 and bcl-2 were all down-regulated, whereas bax was up-regulated. The molecular determinants of inhibition of cell proliferation as well as apoptosis of CSE may be associated with cycle arrest in the S phase.

Role of Mitochondrial Complex IV in Age-Dependent Obesity

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Ines Soro-Arnaiz

2016-09-01

Full Text Available Aging is associated with progressive white adipose tissue (WAT enlargement initiated early in life, but the molecular mechanisms involved remain unknown. Here we show that mitochondrial complex IV (CIV activity and assembly are already repressed in white adipocytes of middle-aged mice and involve a HIF1A-dependent decline of essential CIV components such as COX5B. At the molecular level, HIF1A binds to the Cox5b proximal promoter and represses its expression. Silencing of Cox5b decreased fatty acid oxidation and promoted intracellular lipid accumulation. Moreover, local in vivo Cox5b silencing in WAT of young mice increased the size of adipocytes, whereas restoration of COX5B expression in aging mice counteracted adipocyte enlargement. An age-dependent reduction in COX5B gene expression was also found in human visceral adipose tissue. Collectively, our findings establish a pivotal role for CIV dysfunction in progressive white adipocyte enlargement during aging, which can be restored to alleviate age-dependent WAT expansion.

A highly rearranged mitochondrial genome in Nycteria parasites (Haemosporidia) from bats

OpenAIRE

Karadjian , Gregory; Hassanin , Alexandre; Saintpierre , Benjamin; Gembu Tungaluna , Guy-Crispin; Ariey , Frederic; Ayala , Francisco J.; Landau , Irene; Duval , Linda

2016-01-01

International audience; Haemosporidia parasites have mostly and abundantly been described using mitochondrial genes, and in particular cytochrome b (cytb). Failure to amplify the mitochondrial cytb gene of Nycteria parasites isolated from Nycteridae bats has been recently reported. Bats are hosts to a diverse and profuse array of Haemosporidia parasites that remain largely unstudied. There is a need to obtain more molecular data from chiropteran parasites. Such data would help to better under...

The use of mitochondrial DNA (mtDNA-investigations in Forensic Sciences

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S. Dawson

1996-07-01

Full Text Available A variety of methods was developed to characterize mtDNA. The initial aim of these techniques was to try and link diseases with specific mitochondrial defects. As a result of the maternal inheritance trait of mtDNA these techniques facilitate studies of the phylogenetic history and population structure of the human population. It has been shown that mitochondrial DNA typing can be of great value for human identification in forensic cases. The identification of victims of mass-disasters or mass-murders, where human remains can be recovered only after many years have passed, is one of the most challenging fields of forensic identification. By using automated DNA sequencing with fluorescent labels, mitochondrial DNA sequences can be generated rapidly and accurately. Computer software facilitates the rapid comparison of individual and reference sequences.

Mitochondrial dysfunction enhances cisplatin resistance in human gastric cancer cells via the ROS-activated GCN2-eIF2α-ATF4-xCT pathway.

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Wang, Sheng-Fan; Chen, Meng-Shian; Chou, Yueh-Ching; Ueng, Yune-Fang; Yin, Pen-Hui; Yeh, Tien-Shun; Lee, Hsin-Chen

2016-11-08

Mitochondrial DNA mutations and defects in mitochondrial enzymes have been identified in gastric cancers, and they might contribute to cancer progression. In previous studies, mitochondrial dysfunction was induced by oligomycin-enhanced chemoresistance to cisplatin. Herein, we dissected the regulatory mechanism for mitochondrial dysfunction-enhanced cisplatin resistance in human gastric cancer cells. Repeated cisplatin treatment-induced cisplatin-resistant cells exhibited high SLC7A11 (xCT) expression, and xCT inhibitors (sulfasalazine or erastin), xCT siRNA, or a GSH synthesis inhibitor (buthionine sulphoximine, BSO) could sensitize these cells to cisplatin. Clinically, the high expression of xCT was associated with a poorer prognosis for gastric cancer patients under adjuvant chemotherapy. Moreover, we found that mitochondrial dysfunction enhanced cisplatin resistance and up-regulated xCT expression, as well as intracellular glutathione (GSH). The xCT inhibitors, siRNA against xCT or BSO decreased mitochondrial dysfunction-enhanced cisplatin resistance. We further demonstrated that the upregulation of the eIF2α-ATF4 pathway contributed to mitochondrial dysfunction-induced xCT expression, and activated eIF2α kinase GCN2, but not PERK, stimulated the eIF2α-ATF4-xCT pathway in response to mitochondrial dysfunction-increased reactive oxygen species (ROS) levels. In conclusion, our results suggested that the ROS-activated GCN2-eIF2α-ATF4-xCT pathway might contribute to mitochondrial dysfunction-enhanced cisplatin resistance and could be a potential target for gastric cancer therapy.

PCR-Free Enrichment of Mitochondrial DNA from Human Blood and Cell Lines for High Quality Next-Generation DNA Sequencing.

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Meetha P Gould

Full Text Available Recent advances in sequencing technology allow for accurate detection of mitochondrial sequence variants, even those in low abundance at heteroplasmic sites. Considerable sequencing cost savings can be achieved by enriching samples for mitochondrial (relative to nuclear DNA. Reduction in nuclear DNA (nDNA content can also help to avoid false positive variants resulting from nuclear mitochondrial sequences (numts. We isolate intact mitochondrial organelles from both human cell lines and blood components using two separate methods: a magnetic bead binding protocol and differential centrifugation. DNA is extracted and further enriched for mitochondrial DNA (mtDNA by an enzyme digest. Only 1 ng of the purified DNA is necessary for library preparation and next generation sequence (NGS analysis. Enrichment methods are assessed and compared using mtDNA (versus nDNA content as a metric, measured by using real-time quantitative PCR and NGS read analysis. Among the various strategies examined, the optimal is differential centrifugation isolation followed by exonuclease digest. This strategy yields >35% mtDNA reads in blood and cell lines, which corresponds to hundreds-fold enrichment over baseline. The strategy also avoids false variant calls that, as we show, can be induced by the long-range PCR approaches that are the current standard in enrichment procedures. This optimization procedure allows mtDNA enrichment for efficient and accurate massively parallel sequencing, enabling NGS from samples with small amounts of starting material. This will decrease costs by increasing the number of samples that may be multiplexed, ultimately facilitating efforts to better understand mitochondria-related diseases.

[Diagnosis of mitochondrial disorders in children with next generation sequencing].

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Liu, Zhimei; Fang, Fang; Ding, Changhong; Zhang, Weihua; Li, Jiuwei; Yang, Xinying; Wang, Xiaohui; Wu, Yun; Wang, Hongmei; Liu, Liying; Han, Tongli; Wang, Xu; Chen, Chunhong; Lyu, Junlan; Wu, Husheng

2015-10-01

To explore the application value of next generation sequencing (NGS) in the diagnosis of mitochondrial disorders. According to mitochondrial disease criteria, genomic DNA was extracted using standard procedure from peripheral venous blood of patients with suspected mitochondrial disease collected from neurological department of Beijing Children's Hospital Affiliated to Capital Medical University between October 2012 and February 2014. Targeted NGS to capture and sequence the entire mtDNA and exons of the 1 000 nuclear genes related to mitochondrial structure and function. Clinical data were collected from patients diagnosed at a molecular level, then clinical features and the relationship between genotype and phenotype were analyzed. Mutation was detected in 21 of 70 patients with suspected mitochondrial disease, in whom 10 harbored mtDNA mutation, while 11 nuclear DNA (nDNA) mutation. In 21 patients, 1 was diagnosed congenital myasthenic syndrome with episodic apnea due to CHAT gene p.I187T homozygous mutation, and 20 were diagnosed mitochondrial disease, in which 10 were Leigh syndrome, 4 were mitochondrial encephalomyopathy with lactic acidosis and stroke like episodes syndrome, 3 were Leber hereditary optic neuropathy (LHON) and LHON plus, 2 were mitochondrial DNA depletion syndrome and 1 was unknown. All the mtDNA mutations were point mutations, which contained A3243G, G3460A, G11778A, T14484C, T14502C and T14487C. Ten mitochondrial disease patients harbored homozygous or compound heterozygous mutations in 5 genes previously shown to cause disease: SURF1, PDHA1, NDUFV1, SUCLA2 and SUCLG1, which had 14 mutations, and 7 of the 14 mutations have not been reported. NGS has a certain application value in the diagnosis of mitochondrial diseases, especially in Leigh syndrome atypical mitochondrial syndrome and rare mitochondrial disorders.

ROS-dependent mitochondria molecular mechanisms underlying antitumor activity of Pleurotus abalonus acidic polysaccharides in human breast cancer MCF-7 cells.

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Xiaolong Shi

Full Text Available BACKGROUND: A greater reduction in cancer risk associated with mushroom diet rich in fungus polysaccharides is generally accepted. Meanwhile, edible Pleurotus abalonus as a member of Abalone mushroom family is a popular nutritional supplement that purportedly prevents cancer occurrence. However, these anecdotal claims are supported by limited studies describing tumor-inhibitory responses to the promising polysaccharides, and the molecular mechanisms underlying these properties have not yet been elucidated. METHODOLOGY/PRINCIPAL FINDINGS: We here fractionated the crude polysaccharide preparation from the fruiting bodies of P. abalonus into three fractions, namely PAP-1, PAP-2 and PAP-3, and tested these fractions for antiproliferative activity in human breast cancer MCF-7 cells. The largest PAP-3, an acidic polysaccharide fraction with a molecular mass of 3.68×10(5 Da, was the most active in inhibiting MCF-7 cancer cells with an IC50 of 193 µg/mL. The changes in cell normal morphology were observed by DAPI staining and the PAP-3-induced apoptosis was confirmed by annexin V/propidium iodide staining. The apoptosis was involved in mitochondria-mediated pathway including the loss of mitochondrial membrane potential (Δψm, the increase of Bax/Bcl-2 ratio, caspase-9/3 activation, and poly(ADP-ribose polymerase (PARP degradation, as well as intracellular ROS production. PAP-3 also induced up-regulation of p53, and cell cycle arrest at the S phase. The incubation of MCF-7 cells with antioxidant superoxide dismutase (SOD and N-acetylcysteine (NAC significantly attenuated the ROS generation and apoptosis caused by PAP-3, indicating that intracellular ROS plays a pivotal role in cell death. CONCLUSIONS/SIGNIFICANCE: These findings suggest that the polysaccharides, especially acidic PAP-3, are very important nutritional ingredients responsible for, at least in part, the anticancer health benefits of P. abalonus via ROS-mediated mitochondrial apoptotic

Genotype-Phenotype Correlation of Maternally Inherited Disorders due to Mutations in Mitochondrial DNA

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Peterus Thajeb

2006-09-01

Full Text Available Mitochondrial disorders are heterogeneous systemic ailments that are most often caused by maternal inheritance of a variety of mutations of the mitochondrial (mt DNA. Paternal inheritance and somatic mutation are rare. The disorders are well recognized not only for the genotypic heterogeneity, but also the phenotypic variation among the affected members of a single family. The genotype-phenotype correlation of the diversity of the syndromic and non-syndromic features of mitochondrial disorders are discussed. Some aspects of the molecular mechanisms of this heterogeneity, and the histopathologic findings are highlighted.

From simple to supercomplex: mitochondrial genomes of euglenozoan protists

Czech Academy of Sciences Publication Activity Database

Faktorová, Drahomíra; Dobáková, Eva; Peña-Diaz, Priscila; Lukeš, Julius

2016-01-01

Roč. 5, 15 NOV (2016), č. článku 392. ISSN 2046-1402 R&D Projects: GA ČR GA15-21974S Institutional support: RVO:60077344 Keywords : euglenozoa * mitochondria * mitochondrial genome Subject RIV: EB - Genetics ; Molecular Biology

The mammalian phosphate carrier SLC25A3 is a mitochondrial copper transporter required for cytochrome c oxidase biogenesis.

Science.gov (United States)

Boulet, Aren; Vest, Katherine E; Maynard, Margaret K; Gammon, Micah G; Russell, Antoinette C; Mathews, Alexander T; Cole, Shelbie E; Zhu, Xinyu; Phillips, Casey B; Kwong, Jennifer Q; Dodani, Sheel C; Leary, Scot C; Cobine, Paul A

2018-02-09

Copper is required for the activity of cytochrome c oxidase (COX), the terminal electron-accepting complex of the mitochondrial respiratory chain. The likely source of copper used for COX biogenesis is a labile pool found in the mitochondrial matrix. In mammals, the proteins that transport copper across the inner mitochondrial membrane remain unknown. We previously reported that the mitochondrial carrier family protein Pic2 in budding yeast is a copper importer. The closest Pic2 ortholog in mammalian cells is the mitochondrial phosphate carrier SLC25A3. Here, to investigate whether SLC25A3 also transports copper, we manipulated its expression in several murine and human cell lines. SLC25A3 knockdown or deletion consistently resulted in an isolated COX deficiency in these cells, and copper addition to the culture medium suppressed these biochemical defects. Consistent with a conserved role for SLC25A3 in copper transport, its heterologous expression in yeast complemented copper-specific defects observed upon deletion of PIC2 Additionally, assays in Lactococcus lactis and in reconstituted liposomes directly demonstrated that SLC25A3 functions as a copper transporter. Taken together, these data indicate that SLC25A3 can transport copper both in vitro and in vivo . © 2018 by The American Society for Biochemistry and Molecular Biology, Inc.

A single Danio rerio hars gene encodes both cytoplasmic and mitochondrial histidyl-tRNA synthetases.

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Ashley L Waldron

Full Text Available Histidyl tRNA Synthetase (HARS is a member of the aminoacyl tRNA synthetase (ARS family of enzymes. This family of 20 enzymes is responsible for attaching specific amino acids to their cognate tRNA molecules, a critical step in protein synthesis. However, recent work highlighting a growing number of associations between ARS genes and diverse human diseases raises the possibility of new and unexpected functions in this ancient enzyme family. For example, mutations in HARS have been linked to two different neurological disorders, Usher Syndrome Type IIIB and Charcot Marie Tooth peripheral neuropathy. These connections raise the possibility of previously undiscovered roles for HARS in metazoan development, with alterations in these functions leading to complex diseases. In an attempt to establish Danio rerio as a model for studying HARS functions in human disease, we characterized the Danio rerio hars gene and compared it to that of human HARS. Using a combination of bioinformatics, molecular biology, and cellular approaches, we found that while the human genome encodes separate genes for cytoplasmic and mitochondrial HARS protein, the Danio rerio genome encodes a single hars gene which undergoes alternative splicing to produce the respective cytoplasmic and mitochondrial versions of Hars. Nevertheless, while the HARS genes of humans and Danio differ significantly at the genomic level, we found that they are still highly conserved at the amino acid level, underscoring the potential utility of Danio rerio as a model organism for investigating HARS function and its link to human diseases in vivo.

The m.3291T>C mt-tRNALeu(UUR) mutation is definitely pathogenic and causes multisystem mitochondrial disease

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Yarham, John W.; Blakely, Emma L.; Alston, Charlotte L.; Roberts, Mark E.; Ealing, John; Pal, Piyali; Turnbull, Douglass M.; McFarland, Robert; Taylor, Robert W.

2013-01-01

Mitochondrial tRNA point mutations are important causes of human disease, and have been associated with a diverse range of clinical phenotypes. Definitively proving the pathogenicity of any given mt-tRNA mutation requires combined molecular, genetic and functional studies. Subsequent evaluation of the mutation using a pathogenicity scoring system is often very helpful in concluding whether or not the mutation is causing disease. Despite several independent reports linking the m.3291T>C mutation to disease in humans, albeit in association with several different phenotypes, its pathogenicity remains controversial. A lack of conclusive functional evidence and an over-emphasis on the poor evolutionary conservation of the affected nucleotide have contributed to this controversy. Here we describe an adult patient who presented with deafness and lipomas and evidence of mitochondrial abnormalities in his muscle biopsy, who harbours the m.3291T > C mutation, providing conclusive evidence of pathogenicity through analysis of mutation segregation with cytochrome c oxidase (COX) deficiency in single muscle fibres, underlining the importance of performing functional studies when assessing pathogenicity. PMID:23273904

Polymorphisms in the mitochondrial ribosome recycling factor EF-G2mt/MEF2 compromise cell respiratory function and increase atorvastatin toxicity.

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Sylvie Callegari

Full Text Available Mitochondrial translation, essential for synthesis of the electron transport chain complexes in the mitochondria, is governed by nuclear encoded genes. Polymorphisms within these genes are increasingly being implicated in disease and may also trigger adverse drug reactions. Statins, a class of HMG-CoA reductase inhibitors used to treat hypercholesterolemia, are among the most widely prescribed drugs in the world. However, a significant proportion of users suffer side effects of varying severity that commonly affect skeletal muscle. The mitochondria are one of the molecular targets of statins, and these drugs have been known to uncover otherwise silent mitochondrial mutations. Based on yeast genetic studies, we identify the mitochondrial translation factor MEF2 as a mediator of atorvastatin toxicity. The human ortholog of MEF2 is the Elongation Factor Gene (EF-G 2, which has previously been shown to play a specific role in mitochondrial ribosome recycling. Using small interfering RNA (siRNA silencing of expression in human cell lines, we demonstrate that the EF-G2mt gene is required for cell growth on galactose medium, signifying an essential role for this gene in aerobic respiration. Furthermore, EF-G2mt silenced cell lines have increased susceptibility to cell death in the presence of atorvastatin. Using yeast as a model, conserved amino acid variants, which arise from non-synonymous single nucleotide polymorphisms (SNPs in the EF-G2mt gene, were generated in the yeast MEF2 gene. Although these mutations do not produce an obvious growth phenotype, three mutations reveal an atorvastatin-sensitive phenotype and further analysis uncovers a decreased respiratory capacity. These findings constitute the first reported phenotype associated with SNPs in the EF-G2mt gene and implicate the human EF-G2mt gene as a pharmacogenetic candidate gene for statin toxicity in humans.

A crosstalk between Na⁺ channels, Na⁺/K⁺ pump and mitochondrial Na⁺ transporters controls glucose-dependent cytosolic and mitochondrial Na⁺ signals.

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Nita, Iulia I; Hershfinkel, Michal; Lewis, Eli C; Sekler, Israel

2015-02-01

Glucose-dependent cytosolic Na(+) influx in pancreatic islet β cells is mediated by TTX-sensitive Na(+) channels and is propagated into the mitochondria through the mitochondrial Na(+)/Ca(2+) exchanger, NCLX. Mitochondrial Na(+) transients are also controlled by the mitochondrial Na(+)/H(+) exchanger, NHE, while cytosolic Na(+) changes are governed by Na(+)/K(+) ATPase pump. The functional interaction between the Na(+) channels, Na(+)/K(+) ATPase pump and mitochondrial Na(+) transporters, NCLX and NHE, in mediating Na(+) signaling is poorly understood. Here, we combine fluorescent Na(+) imaging, pharmacological inhibition by TTX, ouabain and EIPA, with molecular control of NCLX expression, so as to investigate the crosstalk between Na(+) transporters on both the plasma membrane and the mitochondria. According to our results, glucose-dependent cytosolic Na(+) response was enhanced by ouabain and was followed by a rise in mitochondrial Na(+) signal. Silencing of NCLX expression using siNCLX, did not affect the glucose- or ouabain-dependent cytosolic rise in Na(+). In contrast, the ouabain-dependent rise in mitochondrial Na(+) was strongly suppressed by siNCLX. Furthermore, mitochondrial Na(+) influx rates were accelerated in cells treated with the Na(+)/H(+) exchanger inhibitor, EIPA or by combination of EIPA and ouabain. Similarly, TTX blocked the cytosolic and mitochondrial Na(+) responses, which were enhanced by ouabain or EIPA, respectively. Our results suggest that Na(+)/K(+) ATPase pump controls cytosolic glucose-dependent Na(+) rise, in a manner that is mediated by TTX-sensitive Na(+) channels and subsequent mitochondrial Na(+) uptake via NCLX. Furthermore, these results indicate that mitochondrial Na(+) influx via NCLX is antagonized by Na(+) efflux, which is mediated by the mitochondrial NHE; thus, the duration of mitochondrial Na(+) transients is set by the interplay between these pivotal transporters. Copyright © 2014 Elsevier Ltd. All rights reserved.

Reactive oxygen species mediates homocysteine-induced mitochondrial biogenesis in human endothelial cells: Modulation by antioxidants

International Nuclear Information System (INIS)

Perez-de-Arce, Karen; Foncea, Rocio; Leighton, Federico

2005-01-01

It has been proposed that homocysteine (Hcy)-induces endothelial dysfunction and atherosclerosis by generation of reactive oxygen species (ROS). A previous report has shown that Hcy promotes mitochondrial damage. Considering that oxidative stress can affect mitochondrial biogenesis, we hypothesized that Hcy-induced ROS in endothelial cells may lead to increased mitochondrial biogenesis. We found that Hcy-induced ROS (1.85-fold), leading to a NF-κB activation and increase the formation of 3-nitrotyrosine. Furthermore, expression of the mitochondrial biogenesis factors, nuclear respiratory factor-1 and mitochondrial transcription factor A, was significantly elevated in Hcy-treated cells. These changes were accompanied by increase in mitochondrial mass and higher mRNA and protein expression of the subunit III of cytochrome c oxidase. These effects were significantly prevented by pretreatment with the antioxidants, catechin and trolox. Taken together, our results suggest that ROS is an important mediator of mitochondrial biogenesis induced by Hcy, and that modulation of oxidative stress by antioxidants may protect against the adverse vascular effects of Hcy

Mitochondrial myopathies.

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DiMauro, Salvatore

2006-11-01

Our understanding of mitochondrial diseases (defined restrictively as defects of the mitochondrial respiratory chain) is expanding rapidly. In this review, I will give the latest information on disorders affecting predominantly or exclusively skeletal muscle. The most recently described mitochondrial myopathies are due to defects in nuclear DNA, including coenzyme Q10 deficiency and mutations in genes controlling mitochondrial DNA abundance and structure, such as POLG, TK2, and MPV17. Barth syndrome, an X-linked recessive mitochondrial myopathy/cardiopathy, is associated with decreased amount and altered structure of cardiolipin, the main phospholipid of the inner mitochondrial membrane, but a secondary impairment of respiratory chain function is plausible. The role of mutations in protein-coding genes of mitochondrial DNA in causing isolated myopathies has been confirmed. Mutations in tRNA genes of mitochondrial DNA can also cause predominantly myopathic syndromes and--contrary to conventional wisdom--these mutations can be homoplasmic. Defects in the mitochondrial respiratory chain impair energy production and almost invariably involve skeletal muscle, causing exercise intolerance, cramps, recurrent myoglobinuria, or fixed weakness, which often affects extraocular muscles and results in droopy eyelids (ptosis) and progressive external ophthalmoplegia.

Mitofilin complexes: conserved organizers of mitochondrial membrane architecture.

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Zerbes, Ralf M; van der Klei, Ida J; Veenhuis, Marten; Pfanner, Nikolaus; van der Laan, Martin; Bohnert, Maria

2012-11-01

Mitofilin proteins are crucial organizers of mitochondrial architecture. They are located in the inner mitochondrial membrane and interact with several protein complexes of the outer membrane, thereby generating contact sites between the two membrane systems of mitochondria. Within the inner membrane, mitofilins are part of hetero-oligomeric protein complexes that have been termed the mitochondrial inner membrane organizing system (MINOS). MINOS integrity is required for the maintenance of the characteristic morphology of the inner mitochondrial membrane, with an inner boundary region closely apposed to the outer membrane and cristae membranes, which form large tubular invaginations that protrude into the mitochondrial matrix and harbor the enzyme complexes of the oxidative phosphorylation machinery. MINOS deficiency comes along with a loss of crista junction structures and the detachment of cristae from the inner boundary membrane. MINOS has been conserved in evolution from unicellular eukaryotes to humans, where alterations of MINOS subunits are associated with multiple pathological conditions.

Molecular evolution of the mitochondrial 12S rRNA in Ungulata (mammalia).

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Douzery, E; Catzeflis, F M

1995-11-01

The complete 12S rRNA gene has been sequenced in 4 Ungulata (hoofed eutherians) and 1 marsupial and compared to 38 available mammalian sequences in order to investigate the molecular evolution of the mitochondrial small-subunit ribosomal RNA molecule. Ungulata were represented by one artiodactyl (the collared peccary, Tayassu tajacu, suborder Suiformes), two perissodactyls (the Grevy's zebra, Equus grevyi, suborder Hippomorpha; the white rhinoceros, Ceratotherium simum, suborder Ceratomorpha), and one hyracoid (the tree hyrax, Dendrohyrax dorsalis). The fifth species was a marsupial, the eastern gray kangaroo (Macropus giganteus). Several transition/transversion biases characterized the pattern of changes between mammalian 12S rRNA molecules. A bias toward transitions was found among 12S rRNA sequences of Ungulata, illustrating the general bias exhibited by ribosomal and protein-encoding genes of the mitochondrial genome. The derivation of a mammalian 12S rRNA secondary structure model from the comparison of 43 eutherian and marsupial sequences evidenced a pronounced bias against transversions in stems. Moreover, transversional compensatory changes were rare events within double-stranded regions of the ribosomal RNA. Evolutionary characteristics of the 12S rRNA were compared with those of the nuclear 18S and 28S rRNAs. From a phylogenetic point of view, transitions, transversions and indels in stems as well as transversional and indels events in loops gave congruent results for comparisons within orders. Some compensatory changes in double-stranded regions and some indels in single-stranded regions also constituted diagnostic events. The 12S rRNA molecule confirmed the monophyly of infraorder Pecora and order Cetacea and demonstrated the monophyly of the suborder Ruminantia was not supported and the branching pattern between Cetacea and the artiodacytyl suborders Ruminantia and Suiformes was not established. The monophyly of the order Perissodactyla was evidenced

Rapid Electrical Stimulation Increased Cardiac Apoptosis Through Disturbance of Calcium Homeostasis and Mitochondrial Dysfunction in Human Induced Pluripotent Stem Cell-Derived Cardiomyocytes

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Le Geng

2018-06-01

Full Text Available Background/Aims: Heart failure induced by tachycardia, the most common arrhythmia, is frequently observed in clinical practice. This study was designed to investigate the underlying mechanisms. Methods: Rapid electrical stimulation (RES at a frequency of 3 Hz was applied on human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs for 7 days, with 8 h/day and 24 h/day set to represent short-term and long-term tachycardia, respectively. Age-matched hiPSC-CMs without electrical stimulation or with slow electrical stimulation (1 Hz were set as no electrical stimulation (NES control or low-frequency electrical stimulation (LES control. Following stimulation, JC-1 staining flow cytometry analysis was performed to examine mitochondrial conditions. Apoptosis in hiPSC-CMs was evaluated using Hoechst staining and Annexin V/propidium iodide (AV/PI staining flow cytometry analysis. Calcium transients and L-type calcium currents were recorded to evaluate calcium homeostasis. Western blotting and qPCR were performed to evaluate the protein and mRNA expression levels of apoptosis-related genes and calcium homeostasis-regulated genes. Results: Compared to the controls, hiPSC-CMs following RES presented mitochondrial dysfunction and an increased apoptotic percentage. Amplitudes of calcium transients and L-type calcium currents were significantly decreased in hiPSC-CMs with RES. Molecular analysis demonstrated upregulated expression of Caspase3 and increased Bax/Bcl-2 ratio. Genes related to calcium re-sequence were downregulated, while phosphorylated Ca2+/calmodulin-dependent protein kinase II (CaMKII was significantly upregulated following RES. There was no significant difference between the NES control and LES control groups in these aspects. Inhibition of CaMKII with 1 µM KN93 partly reversed these adverse effects of RES. Conclusion: RES on hiPSC-CMs disturbed calcium homeostasis, which led to mitochondrial stress, promoted cell apoptosis and

Study on Distribution and location of selenium and other elements in different mitochondrial compartments of human liver by neutron activation analysis

International Nuclear Information System (INIS)

Xing Li; Chen Chunying; Li Bai; Yu Hongwei; Chai Zhifang

2005-01-01

Mitochondria are membrane-bound organelles and contain many kinds of enzymes and proteins. Mitochondria are the energy factories of the eukaryote cells, which play essential physiological roles in cells and principally produce the bulk of cellular ATP through oxidative metabolism. Mitochondria not only play crucial roles in the process of energy conversion but also take part in other functions, including maintaining ion homeostasis, metabolism and apoptosis. Therefore, it is considered as a key biomonitor of cell apoptosis, which is closely relevant to cell survival or death. As the main place of metabolism and detoxification, liver may contain relatively high levels of many trace elements. Subcellular distribution patterns of some elements in human liver have been analyzed in our previous work. However, the distribution of trace elements in mitochondrial ultrastructure has not been investigated yet. In present study, the distribution patterns of eleven elements in mitochondrial subfractions of normal human liver specimens were studied by applying the separating techniques of chemical treatment and differential centrifugation combined with element-specific detection of instrumental neutron activation analysis (INAA) and hydrid-generation atomic fluorescence spectrometry (HG-AFS). The quality assurance of INAA was checked by the analysis of the reference material of NIST bovine liver (1577a) and the Chinese reference materials of mussel (GBW 08571) and poplar leave (GBW 07604). Because selenium is possible to be lost via volatilization under such a long irradiation of 48 hrs, its content was determined with HG-AFS. We found that 3.3 % of the total mitochondrial protein were located in the outer membrane, 20.4 % in the intermembrane space, 63.8 % in the inner membrane and 12.5 % in the matrix of human liver mitochondria. The concentrations of Ca, Co and Zn were highest in the matrix and Ba, Cr, Fe, Sb, Sc, and Th in the outer membrane, whereas, the highest

Outbreak of human malaria caused by Plasmodium simium in the Atlantic Forest in Rio de Janeiro: a molecular epidemiological investigation.

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Brasil, Patrícia; Zalis, Mariano Gustavo; de Pina-Costa, Anielle; Siqueira, Andre Machado; Júnior, Cesare Bianco; Silva, Sidnei; Areas, André Luiz Lisboa; Pelajo-Machado, Marcelo; de Alvarenga, Denise Anete Madureira; da Silva Santelli, Ana Carolina Faria; Albuquerque, Hermano Gomes; Cravo, Pedro; Santos de Abreu, Filipe Vieira; Peterka, Cassio Leonel; Zanini, Graziela Maria; Suárez Mutis, Martha Cecilia; Pissinatti, Alcides; Lourenço-de-Oliveira, Ricardo; de Brito, Cristiana Ferreira Alves; de Fátima Ferreira-da-Cruz, Maria; Culleton, Richard; Daniel-Ribeiro, Cláudio Tadeu

2017-10-01

Malaria was eliminated from southern and southeastern Brazil over 50 years ago. However, an increasing number of autochthonous episodes attributed to Plasmodium vivax have recently been reported from the Atlantic Forest region of Rio de Janeiro state. As the P vivax-like non-human primate malaria parasite species Plasmodium simium is locally enzootic, we performed a molecular epidemiological investigation to determine whether zoonotic malaria transmission is occurring. We examined blood samples from patients presenting with signs or symptoms suggestive of malaria as well as from local howler monkeys by microscopy and PCR. Samples were included from individuals if they had a history of travel to or resided in areas within the Rio de Janeiro Atlantic Forest, but not if they had malaria prophylaxis, blood transfusion or tissue or organ transplantation, or had travelled to known malaria endemic areas in the preceding year. Additionally, we developed a molecular assay based on sequencing of the parasite mitochondrial genome to distinguish between P vivax and P simium, and applied this assay to 33 cases from outbreaks that occurred in 2015, and 2016. A total of 49 autochthonous malaria cases were reported in 2015-16. Most patients were male, with a mean age of 44 years (SD 14·6), and 82% lived in urban areas of Rio de Janeiro state and had visited the Atlantic Forest for leisure or work-related activities. 33 cases were used for mitochondrial DNA sequencing. The assay was successfully performed for 28 samples, and all were shown to be P simium, indicative of zoonotic transmission of this species to human beings in this region. Sequencing of the whole mitochondrial genome of three of these cases showed that P simium is most closely related to P vivax parasites from South America. The malaria outbreaks in this region were caused by P simium, previously considered to be a monkey-specific malaria parasite, related to but distinct from P vivax, and which has never

Proteomic investigations of lysine acetylation identify diverse substrates of mitochondrial deacetylase sirt3

DEFF Research Database (Denmark)

Sol, E-ri Maria; Wagner, Sebastian A; Weinert, Brian T

2012-01-01

Lysine acetylation is a posttranslational modification that is dynamically regulated by the activity of acetyltransferases and deacetylases. The human and mouse genomes encode 18 different lysine deacetylases (KDACs) which are key regulators of many cellular processes. Identifying substrates...... of KDACs and pinpointing the regulated acetylation sites on target proteins may provide important information about the molecular basis of their functions. Here we apply quantitative proteomics to identify endogenous substrates of the mitochondrial deacetylase Sirtuin 3 (Sirt3) by comparing site...... by modulating acetylation on diverse substrates. The experimental strategy described here is generic and can be applied to identify endogenous substrates of other lysine deacetylases....

Human mitochondrial DNA (mtDNA) types in Malaysia

International Nuclear Information System (INIS)

Lian, L.H.; Koh, C.L.; Lim, M.E.

2000-01-01

Each human cell contains hundreds of mitochondria and thousands of double-stranded circular mtDNA. The delineation of human mtDNA variation and genetics over the past decade has provided unique and often startling insights into human evolution, degenerative diseases, and aging. Each mtDNA of 16,569 base pairs, encodes 13 polypeptides essential to the enzymes of the mitochondrial energy generating pathway, plus the necessary tRNAs and rRNAs. The highly polymorphic noncoding D-(displacement) loop region, also called the control region, is approximately 1.2 kb long. It contains two well-characterized hypervariable (HV-) regions, HV1 and HV2. MtDNA identification is usually based on these sequence differences. According to the TWTGDAM (Technical Working Group for DNA Analysis Methods), the minimum requirement for a mtDNA database for HV1 is from positions 16024 to 16365 and for HV2, from positions 00073 to 00340. The targeted Malaysian population subgroups for this study were mainly the Malays, Chinese, Indians, and indigenous Ibans, Bidayuhs, Kadazan-Dusuns, and Bajaus. Research methodologies undertaken included DNA extraction of samples from unrelated individuals, amplification of the specific regions via the polymerase chain reaction (PCR), and preparation of template DNA for sequencing by using an automated DNA sequencer. Sufficient nucleotide sequence data were generated from the mtDNA analysis. When the sequences were analyzed, sequence variations were found to be caused by nucleotide substitutions, insertions, and deletions. Of the three causes of the sequence variations, nucleotide substitutions (86.1%) accounted for the vast majority of polymorphism. It is noted that transitions (83.5%) were predominant when compared to the significantly lower frequencies of transversions (2.6%). Insertions (0.9%) and deletions (13.0%) were rather rare and found only in HV2. The data generated will also form the basis of a Malaysian DNA sequence database of mtDNA D

Mitochondrial dysfunction in the neuro-degenerative and cardio-degenerative disease, Friedreich's ataxia.

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Chiang, Shannon; Kalinowski, Danuta S; Jansson, Patric J; Richardson, Des R; Huang, Michael L-H

2017-08-04

Mitochondrial homeostasis is essential for maintaining healthy cellular function and survival. The detrimental involvement of mitochondrial dysfunction in neuro-degenerative diseases has recently been highlighted in human conditions, such as Parkinson's, Alzheimer's and Huntington's disease. Friedreich's ataxia (FA) is another neuro-degenerative, but also cardio-degenerative condition, where mitochondrial dysfunction plays a crucial role in disease progression. Deficient expression of the mitochondrial protein, frataxin, is the primary cause of FA, which leads to adverse alterations in whole cell and mitochondrial iron metabolism. Dys-regulation of iron metabolism in these compartments, results in the accumulation of inorganic iron deposits in the mitochondrial matrix that is thought to potentiate oxidative damage observed in FA. Therefore, the maintenance of mitochondrial homeostasis is crucial in the progression of neuro-degenerative conditions, particularly in FA. In this review, vital mitochondrial homeostatic processes and their roles in FA pathogenesis will be discussed. These include mitochondrial iron processing, mitochondrial dynamics (fusion and fission processes), mitophagy, mitochondrial biogenesis, mitochondrial energy production and calcium metabolism. Copyright © 2017 Elsevier Ltd. All rights reserved.

Novel cell-based assay reveals associations of circulating serum AhR-ligands with metabolic syndrome and mitochondrial dysfunction.

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Park, Wook-Ha; Jun, Dae Won; Kim, Jin Taek; Jeong, Jae Hoon; Park, Hyokeun; Chang, Yoon-Seok; Park, Kyong Soo; Lee, Hong Kyu; Pak, Youngmi Kim

2013-01-01

Serum concentrations of environmental pollutants have been positively correlated with diabetes and metabolic syndrome in epidemiologic studies. In turn, abnormal mitochondrial function has been associated with the diseases. The relationships between these variables, however, have not been studied. We developed novel cell-based aryl hydrocarbon receptor (AhR) agonist bioassay system without solvent extraction process and analyzed whether low-dose circulating AhR ligands in human serum are associated with parameters of metabolic syndrome and mitochondrial function. Serum AhR ligand activities were measured as serum 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalent (sTCDDeq) in pM using 10 μL human sera from 97 Korean participants (47 with glucose intolerance and 50 matched controls, average age of 46.6 ± 9.9 years, 53 male and 45 female). sTCDDeq were higher in participants with glucose intolerance than normal controls and were positively associated (P fasting glucose, but not with HDL-cholesterol. Body mass index was in a positive linear relationship with serum AhR ligands in healthy participants. When myoblast cells were incubated with human sera, ATP generating power of mitochondria became impaired in an AhR ligand concentration-dependent manner. Our results support that circulating AhR ligands may directly reduce mitochondrial function in tissues, leading to weight gain, glucose intolerance, and metabolic syndrome. Our rapid cell-based assay using minute volume of human serum may provide one of the best monitoring systems for circulating AhR ligands, good clinical biomarkers for the progress of disease and therapeutic efficacy. Copyright © 2013 International Union of Biochemistry and Molecular Biology, Inc.

AKIP1 expression modulates mitochondrial function in rat neonatal cardiomyocytes.

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Hongjuan Yu

Full Text Available A kinase interacting protein 1 (AKIP1 is a molecular regulator of protein kinase A and nuclear factor kappa B signalling. Recent evidence suggests AKIP1 is increased in response to cardiac stress, modulates acute ischemic stress response, and is localized to mitochondria in cardiomyocytes. The mitochondrial function of AKIP1 is, however, still elusive. Here, we investigated the mitochondrial function of AKIP1 in a neonatal cardiomyocyte model of phenylephrine (PE-induced hypertrophy. Using a seahorse flux analyzer we show that PE stimulated the mitochondrial oxygen consumption rate (OCR in cardiomyocytes. This was partially dependent on PE mediated AKIP1 induction, since silencing of AKIP1 attenuated the increase in OCR. Interestingly, AKIP1 overexpression alone was sufficient to stimulate mitochondrial OCR and in particular ATP-linked OCR. This was also true when pyruvate was used as a substrate, indicating that it was independent of glycolytic flux. The increase in OCR was independent of mitochondrial biogenesis, changes in ETC density or altered mitochondrial membrane potential. In fact, the respiratory flux was elevated per amount of ETC, possibly through enhanced ETC coupling. Furthermore, overexpression of AKIP1 reduced and silencing of AKIP1 increased mitochondrial superoxide production, suggesting that AKIP1 modulates the efficiency of electron flux through the ETC. Together, this suggests that AKIP1 overexpression improves mitochondrial function to enhance respiration without excess superoxide generation, thereby implicating a role for AKIP1 in mitochondrial stress adaptation. Upregulation of AKIP1 during different forms of cardiac stress may therefore be an adaptive mechanism to protect the heart.

Chronology of deep nodes in the neotropical primate phylogeny: insights from mitochondrial genomes.

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Schrago, Carlos G; Menezes, Albert N; Moreira, Miguel A M; Pissinatti, Alcides; Seuánez, Hector N

2012-01-01

The evolution of Neotropical Primates (NP) is permeated by factors associated with the pattern of diversification and the biogeography of the major lineages. These questions can be better understood by providing a robust estimate of the chronological scenario of NP evolution, a reason why molecular dating methods have been widely applied. One aspect of especial interest is the timing of diversification of the major NP lineages (pitheciids, atelids and cebids), which may have resulted from rapid episodes of adaptive radiation, a question that requires NP divergence time estimates with accurate statistical certainty. In this study, we evaluated the primate timescale focused on the age of nodes of NP radiation. We investigated the performance of complete primate mitochondrial genomes as traditional molecular markers of primate evolution and further including original mitochondrial data from the endangered muriqui, Brachyteles arachnoides (Accession No. JX262672). Comparisons of the age estimates at NP nodes based on mitochondrial genomes with those obtained from a nuclear supermatrix showed similar degrees of uncertainty. Further molecular data and more informative calibration priors are required for a more precise understanding of the early NP diversification.

Chronology of deep nodes in the neotropical primate phylogeny: insights from mitochondrial genomes.

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Carlos G Schrago

Full Text Available The evolution of Neotropical Primates (NP is permeated by factors associated with the pattern of diversification and the biogeography of the major lineages. These questions can be better understood by providing a robust estimate of the chronological scenario of NP evolution, a reason why molecular dating methods have been widely applied. One aspect of especial interest is the timing of diversification of the major NP lineages (pitheciids, atelids and cebids, which may have resulted from rapid episodes of adaptive radiation, a question that requires NP divergence time estimates with accurate statistical certainty. In this study, we evaluated the primate timescale focused on the age of nodes of NP radiation. We investigated the performance of complete primate mitochondrial genomes as traditional molecular markers of primate evolution and further including original mitochondrial data from the endangered muriqui, Brachyteles arachnoides (Accession No. JX262672. Comparisons of the age estimates at NP nodes based on mitochondrial genomes with those obtained from a nuclear supermatrix showed similar degrees of uncertainty. Further molecular data and more informative calibration priors are required for a more precise understanding of the early NP diversification.

Betaine is a positive regulator of mitochondrial respiration

Energy Technology Data Exchange (ETDEWEB)

Lee, Icksoo, E-mail: icksoolee@dankook.ac.kr

2015-01-09

Highlights: • Betaine enhances cytochrome c oxidase activity and mitochondrial respiration. • Betaine increases mitochondrial membrane potential and cellular energy levels. • Betaine’s anti-tumorigenic effect might be due to a reversal of the Warburg effect. - Abstract: Betaine protects cells from environmental stress and serves as a methyl donor in several biochemical pathways. It reduces cardiovascular disease risk and protects liver cells from alcoholic liver damage and nonalcoholic steatohepatitis. Its pretreatment can rescue cells exposed to toxins such as rotenone, chloroform, and LiCl. Furthermore, it has been suggested that betaine can suppress cancer cell growth in vivo and in vitro. Mitochondrial electron transport chain (ETC) complexes generate the mitochondrial membrane potential, which is essential to produce cellular energy, ATP. Reduced mitochondrial respiration and energy status have been found in many human pathological conditions including aging, cancer, and neurodegenerative disease. In this study we investigated whether betaine directly targets mitochondria. We show that betaine treatment leads to an upregulation of mitochondrial respiration and cytochrome c oxidase activity in H2.35 cells, the proposed rate limiting enzyme of ETC in vivo. Following treatment, the mitochondrial membrane potential was increased and cellular energy levels were elevated. We propose that the anti-proliferative effects of betaine on cancer cells might be due to enhanced mitochondrial function contributing to a reversal of the Warburg effect.

Selective downregulation of mitochondrial electron transport chain activity and increased oxidative stress in human atrial fibrillation.

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Emelyanova, Larisa; Ashary, Zain; Cosic, Milanka; Negmadjanov, Ulugbek; Ross, Gracious; Rizvi, Farhan; Olet, Susan; Kress, David; Sra, Jasbir; Tajik, A Jamil; Holmuhamedov, Ekhson L; Shi, Yang; Jahangir, Arshad

2016-07-01

Mitochondria are critical for maintaining normal cardiac function, and a deficit in mitochondrial energetics can lead to the development of the substrate that promotes atrial fibrillation (AF) and its progression. However, the link between mitochondrial dysfunction and AF in humans is still not fully defined. The aim of this study was to elucidate differences in the functional activity of mitochondrial oxidative phosphorylation (OXPHOS) complexes and oxidative stress in right atrial tissue from patients without (non-AF) and with AF (AF) who were undergoing open-heart surgery and were not significantly different for age, sex, major comorbidities, and medications. The overall functional activity of the electron transport chain (ETC), NADH:O2 oxidoreductase activity, was reduced by 30% in atrial tissue from AF compared with non-AF patients. This was predominantly due to a selective reduction in complex I (0.06 ± 0.007 vs. 0.09 ± 0.006 nmol·min(-1)·citrate synthase activity(-1), P = 0.02) and II (0.11 ± 0.012 vs. 0.16 ± 0.012 nmol·min(-1)·citrate synthase activity(-1), P = 0.003) functional activity in AF patients. Conversely, complex V activity was significantly increased in AF patients (0.21 ± 0.027 vs. 0.12 ± 0.01 nmol·min(-1)·citrate synthase activity(-1), P = 0.005). In addition, AF patients exhibited a higher oxidative stress with increased production of mitochondrial superoxide (73 ± 17 vs. 11 ± 2 arbitrary units, P = 0.03) and 4-hydroxynonenal level (77.64 ± 30.2 vs. 9.83 ± 2.83 ng·mg(-1) protein, P = 0.048). Our findings suggest that AF is associated with selective downregulation of ETC activity and increased oxidative stress that can contribute to the progression of the substrate for AF. Copyright © 2016 the American Physiological Society.

The Plant Decapeptide OSIP108 Can Alleviate Mitochondrial Dysfunction Induced by Cisplatin in Human Cells

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Pieter Spincemaille

2014-09-01

Full Text Available We investigated the effect of the Arabidopsis thaliana-derived decapeptide OSIP108 on human cell tolerance to the chemotherapeutic agent cisplatin (Cp, which induces apoptosis and mitochondrial dysfunction. We found that OSIP108 increases the tolerance of HepG2 cells to Cp and prevents Cp-induced changes in basic cellular metabolism. More specifically, we demonstrate that OSIP108 reduces Cp-induced inhibition of respiration, decreases glycolysis and prevents Cp-uptake in HepG2 cells. Apart from its protective action against Cp in human cells, OSIP108 also increases the yeast Saccharomyces cerevisiae tolerance to Cp. A limited yeast-based study of OSIP108 analogs showed that cyclization does not severely affect its activity, which was further confirmed in HepG2 cells. Furthermore, the similarity in the activity of the D-stereoisomer (mirror image form of OSIP108 with the L-stereoisomer suggests that its mode of action does not involve binding to a stereospecific receptor. In addition, as OSIP108 decreases Cp uptake in HepG2 cells and the anti-Cp activity of OSIP108 analogs without free cysteine is reduced, OSIP108 seems to protect against Cp-induced toxicity only partly via complexation. Taken together, our data indicate that OSIP108 and its cyclic derivatives can protect against Cp-induced toxicity and, thus, show potential as treatment options for mitochondrial dysfunction- and apoptosis-related conditions.

Vimar Is a Novel Regulator of Mitochondrial Fission through Miro.

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Lianggong Ding

2016-10-01

Full Text Available As fundamental processes in mitochondrial dynamics, mitochondrial fusion, fission and transport are regulated by several core components, including Miro. As an atypical Rho-like small GTPase with high molecular mass, the exchange of GDP/GTP in Miro may require assistance from a guanine nucleotide exchange factor (GEF. However, the GEF for Miro has not been identified. While studying mitochondrial morphology in Drosophila, we incidentally observed that the loss of vimar, a gene encoding an atypical GEF, enhanced mitochondrial fission under normal physiological conditions. Because Vimar could co-immunoprecipitate with Miro in vitro, we speculated that Vimar might be the GEF of Miro. In support of this hypothesis, a loss-of-function (LOF vimar mutant rescued mitochondrial enlargement induced by a gain-of-function (GOF Miro transgene; whereas a GOF vimar transgene enhanced Miro function. In addition, vimar lost its effect under the expression of a constitutively GTP-bound or GDP-bound Miro mutant background. These results indicate a genetic dependence of vimar on Miro. Moreover, we found that mitochondrial fission played a functional role in high-calcium induced necrosis, and a LOF vimar mutant rescued the mitochondrial fission defect and cell death. This result can also be explained by vimar's function through Miro, because Miro's effect on mitochondrial morphology is altered upon binding with calcium. In addition, a PINK1 mutant, which induced mitochondrial enlargement and had been considered as a Drosophila model of Parkinson's disease (PD, caused fly muscle defects, and the loss of vimar could rescue these defects. Furthermore, we found that the mammalian homolog of Vimar, RAP1GDS1, played a similar role in regulating mitochondrial morphology, suggesting a functional conservation of this GEF member. The Miro/Vimar complex may be a promising drug target for diseases in which mitochondrial fission and fusion are dysfunctional.

Expression of Mitochondrial Non-coding RNAs (ncRNAs) Is Modulated by High Risk Human Papillomavirus (HPV) Oncogenes*

Science.gov (United States)

Villota, Claudio; Campos, América; Vidaurre, Soledad; Oliveira-Cruz, Luciana; Boccardo, Enrique; Burzio, Verónica A.; Varas, Manuel; Villegas, Jaime; Villa, Luisa L.; Valenzuela, Pablo D. T.; Socías, Miguel; Roberts, Sally; Burzio, Luis O.

2012-01-01

The study of RNA and DNA oncogenic viruses has proved invaluable in the discovery of key cellular pathways that are rendered dysfunctional during cancer progression. An example is high risk human papillomavirus (HPV), the etiological agent of cervical cancer. The role of HPV oncogenes in cellular immortalization and transformation has been extensively investigated. We reported the differential expression of a family of human mitochondrial non-coding RNAs (ncRNAs) between normal and cancer cells. Normal cells express a sense mitochondrial ncRNA (SncmtRNA) that seems to be required for cell proliferation and two antisense transcripts (ASncmtRNAs). In contrast, the ASncmtRNAs are down-regulated in cancer cells. To shed some light on the mechanisms that trigger down-regulation of the ASncmtRNAs, we studied human keratinocytes (HFK) immortalized with HPV. Here we show that immortalization of HFK with HPV-16 or 18 causes down-regulation of the ASncmtRNAs and induces the expression of a new sense transcript named SncmtRNA-2. Transduction of HFK with both E6 and E7 is sufficient to induce expression of SncmtRNA-2. Moreover, E2 oncogene is involved in down-regulation of the ASncmtRNAs. Knockdown of E2 in immortalized cells reestablishes in a reversible manner the expression of the ASncmtRNAs, suggesting that endogenous cellular factors(s) could play functions analogous to E2 during non-HPV-induced oncogenesis. PMID:22539350

Expression of mitochondrial non-coding RNAs (ncRNAs) is modulated by high risk human papillomavirus (HPV) oncogenes.

Science.gov (United States)

Villota, Claudio; Campos, América; Vidaurre, Soledad; Oliveira-Cruz, Luciana; Boccardo, Enrique; Burzio, Verónica A; Varas, Manuel; Villegas, Jaime; Villa, Luisa L; Valenzuela, Pablo D T; Socías, Miguel; Roberts, Sally; Burzio, Luis O

2012-06-15

The study of RNA and DNA oncogenic viruses has proved invaluable in the discovery of key cellular pathways that are rendered dysfunctional during cancer progression. An example is high risk human papillomavirus (HPV), the etiological agent of cervical cancer. The role of HPV oncogenes in cellular immortalization and transformation has been extensively investigated. We reported the differential expression of a family of human mitochondrial non-coding RNAs (ncRNAs) between normal and cancer cells. Normal cells express a sense mitochondrial ncRNA (SncmtRNA) that seems to be required for cell proliferation and two antisense transcripts (ASncmtRNAs). In contrast, the ASncmtRNAs are down-regulated in cancer cells. To shed some light on the mechanisms that trigger down-regulation of the ASncmtRNAs, we studied human keratinocytes (HFK) immortalized with HPV. Here we show that immortalization of HFK with HPV-16 or 18 causes down-regulation of the ASncmtRNAs and induces the expression of a new sense transcript named SncmtRNA-2. Transduction of HFK with both E6 and E7 is sufficient to induce expression of SncmtRNA-2. Moreover, E2 oncogene is involved in down-regulation of the ASncmtRNAs. Knockdown of E2 in immortalized cells reestablishes in a reversible manner the expression of the ASncmtRNAs, suggesting that endogenous cellular factors(s) could play functions analogous to E2 during non-HPV-induced oncogenesis.

Oxidative stress, mitochondrial abnormalities and antioxidant defense in Ataxia-telangiectasia, Bloom syndrome and Nijmegen breakage syndrome

Directory of Open Access Journals (Sweden)

Mateusz Maciejczyk

2017-04-01

Full Text Available Rare pleiotropic genetic disorders, Ataxia-telangiectasia (A-T, Bloom syndrome (BS and Nijmegen breakage syndrome (NBS are characterised by immunodeficiency, extreme radiosensitivity, higher cancer susceptibility, premature aging, neurodegeneration and insulin resistance. Some of these functional abnormalities can be explained by aberrant DNA damage response and chromosomal instability. It has been suggested that one possible common denominator of these conditions could be chronic oxidative stress caused by endogenous ROS overproduction and impairment of mitochondrial homeostasis. Recent studies indicate new, alternative sources of oxidative stress in A-T, BS and NBS cells, including NADPH oxidase 4 (NOX4, oxidised low-density lipoprotein (ox-LDL or Poly (ADP-ribose polymerases (PARP. Mitochondrial abnormalities such as changes in the ultrastructure and function of mitochondria, excess mROS production as well as mitochondrial damage have also been reported in A-T, BS and NBS cells. A-T, BS and NBS cells are inextricably linked to high levels of reactive oxygen species (ROS, and thereby, chronic oxidative stress may be a major phenotypic hallmark in these diseases. Due to the presence of mitochondrial disturbances, A-T, BS and NBS may be considered mitochondrial diseases. Excess activity of antioxidant enzymes and an insufficient amount of low molecular weight antioxidants indicate new pharmacological strategies for patients suffering from the aforementioned diseases. However, at the current stage of research we are unable to ascertain if antioxidants and free radical scavengers can improve the condition or prolong the survival time of A-T, BS and NBS patients. Therefore, it is necessary to conduct experimental studies in a human model.

Mitochondrial modulation of oxygen-dependent radiosensitivity in some human tumour cell lines.

LENUS (Irish Health Repository)

Anoopkumar-Dukie, S

2009-10-01

Oxygen-dependent radiosensitivity of tumour cells reflects direct oxidative damage to DNA, but non-nuclear mechanisms including signalling pathways may also contribute. Mitochondria are likely candidates because not only do they integrate signals from each of the main kinase pathways but mitochondrial kinases responsive to oxidative stress communicate to the rest of the cell. Using pharmacological and immunochemical methods, we tested the role of mitochondrial permeability transition (MPT) and the Bcl-2 proteins in oxygen-dependent radiosensitivity. Drug-treated or untreated cervical cancer HeLa, breast cancer MCF-7 and melanoma MeWo cell lines were irradiated at 6.2 Gy under normoxic and hypoxic conditions then allowed to proliferate for 7 days. The MPT blocker cyclosporin A (2 microM) strongly protected HeLa but not the other two lines against oxygen-dependent radiosensitivity. By contrast, bongkrekic acid (50 microM), which blocks MPT by targeting the adenine nucleotide transporter, had only marginal effect and calcineurin inhibitor FK-506 (0.1 microM) had none. Nor was evidence found for the modulation of oxygen-dependent radiosensitivity by Bax\\/Bcl-2 signalling, mitochondrial ATP-dependent potassium (mitoK(ATP)) channels or mitochondrial Ca(2+) uptake. In conclusion, calcineurin-independent protection by cyclosporin A suggests that MPT but not mitoK(ATP) or the mitochondrial apoptosis pathway plays a causal role in oxygen-dependent radiosensitivity of HeLa cells. Targeting MPT may therefore improve the effectiveness of radiotherapy in some solid tumours.

Human TRMU encoding the mitochondrial 5-methylaminomethyl-2-thiouridylate-methyltransferase is a putative nuclear modifier gene for the phenotypic expression of the deafness-associated 12S rRNA mutations

International Nuclear Information System (INIS)

Yan Qingfeng; Bykhovskaya, Yelena; Li Ronghua; Mengesha, Emebet; Shohat, Mordechai; Estivill, Xavier; Fischel-Ghodsian, Nathan; Guan Minxin

2006-01-01

Nuclear modifier genes have been proposed to modulate the phenotypic manifestation of human mitochondrial 12S rRNA A1491G mutation associated with deafness in many families world-wide. Here we identified and characterized the putative nuclear modifier gene TRMU encoding a highly conserved mitochondrial protein related to tRNA modification. A 1937 bp TRMU cDNA has been isolated and the genomic organization of TRMU has been elucidated. The human TRMU gene containing 11 exons encodes a 421 residue protein with a strong homology to the TRMU-like proteins of bacteria and other homologs. TRMU is ubiquitously expressed in various tissues, but abundantly in tissues with high metabolic rates including heart, liver, kidney, and brain. Immunofluorescence analysis of human 143B cells expressing TRMU-GFP fusion protein demonstrated that the human Trmu localizes and functions in mitochondrion. Furthermore, we show that in families with the deafness-associated 12S rRNA A1491G mutation there is highly suggestive linkage and linkage disequilibrium between microsatellite markers adjacent to TRMU and the presence of deafness. These observations suggest that human TRMU may modulate the phenotypic manifestation of the deafness-associated mitochondrial 12S rRNA mutations

Mitochondrial Alterations and Oxidative Stress in an Acute Transient Mouse Model of Muscle Degeneration

Science.gov (United States)

Ramadasan-Nair, Renjini; Gayathri, Narayanappa; Mishra, Sudha; Sunitha, Balaraju; Mythri, Rajeswara Babu; Nalini, Atchayaram; Subbannayya, Yashwanth; Harsha, Hindalahalli Chandregowda; Kolthur-Seetharam, Ullas; Bharath, Muchukunte Mukunda Srinivas

2014-01-01

Muscular dystrophies (MDs) and inflammatory myopathies (IMs) are debilitating skeletal muscle disorders characterized by common pathological events including myodegeneration and inflammation. However, an experimental model representing both muscle pathologies and displaying most of the distinctive markers has not been characterized. We investigated the cardiotoxin (CTX)-mediated transient acute mouse model of muscle degeneration and compared the cardinal features with human MDs and IMs. The CTX model displayed degeneration, apoptosis, inflammation, loss of sarcolemmal complexes, sarcolemmal disruption, and ultrastructural changes characteristic of human MDs and IMs. Cell death caused by CTX involved calcium influx and mitochondrial damage both in murine C2C12 muscle cells and in mice. Mitochondrial proteomic analysis at the initial phase of degeneration in the model detected lowered expression of 80 mitochondrial proteins including subunits of respiratory complexes, ATP machinery, fatty acid metabolism, and Krebs cycle, which further decreased in expression during the peak degenerative phase. The mass spectrometry (MS) data were supported by enzyme assays, Western blot, and histochemistry. The CTX model also displayed markers of oxidative stress and a lowered glutathione reduced/oxidized ratio (GSH/GSSG) similar to MDs, human myopathies, and neurogenic atrophies. MS analysis identified 6 unique oxidized proteins from Duchenne muscular dystrophy samples (n = 6) (versus controls; n = 6), including two mitochondrial proteins. Interestingly, these mitochondrial proteins were down-regulated in the CTX model thereby linking oxidative stress and mitochondrial dysfunction. We conclude that mitochondrial alterations and oxidative damage significantly contribute to CTX-mediated muscle pathology with implications for human muscle diseases. PMID:24220031

Endurance exercise rescues progeroid aging and induces systemic mitochondrial rejuvenation in mtDNA mutator mice

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Safdar, Adeel; Bourgeois, Jacqueline M.; Ogborn, Daniel I.; Little, Jonathan P.; Hettinga, Bart P.; Akhtar, Mahmood; Thompson, James E.; Melov, Simon; Mocellin, Nicholas J.; Kujoth, Gregory C.; Prolla, Tomas A.; Tarnopolsky, Mark A.

2011-01-01

A causal role for mitochondrial DNA (mtDNA) mutagenesis in mammalian aging is supported by recent studies demonstrating that the mtDNA mutator mouse, harboring a defect in the proofreading-exonuclease activity of mitochondrial polymerase gamma, exhibits accelerated aging phenotypes characteristic of human aging, systemic mitochondrial dysfunction, multisystem pathology, and reduced lifespan. Epidemiologic studies in humans have demonstrated that endurance training reduces the risk of chronic diseases and extends life expectancy. Whether endurance exercise can attenuate the cumulative systemic decline observed in aging remains elusive. Here we show that 5 mo of endurance exercise induced systemic mitochondrial biogenesis, prevented mtDNA depletion and mutations, increased mitochondrial oxidative capacity and respiratory chain assembly, restored mitochondrial morphology, and blunted pathological levels of apoptosis in multiple tissues of mtDNA mutator mice. These adaptations conferred complete phenotypic protection, reduced multisystem pathology, and prevented premature mortality in these mice. The systemic mitochondrial rejuvenation through endurance exercise promises to be an effective therapeutic approach to mitigating mitochondrial dysfunction in aging and related comorbidities. PMID:21368114

Therapeutically targeting mitochondrial redox signalling alleviates endothelial dysfunction in preeclampsia.

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McCarthy, Cathal; Kenny, Louise C

2016-09-08

Aberrant placentation generating placental oxidative stress is proposed to play a critical role in the pathophysiology of preeclampsia. Unfortunately, therapeutic trials of antioxidants have been uniformly disappointing. There is provisional evidence implicating mitochondrial dysfunction as a source of oxidative stress in preeclampsia. Here we provide evidence that mitochondrial reactive oxygen species mediates endothelial dysfunction and establish that directly targeting mitochondrial scavenging may provide a protective role. Human umbilical vein endothelial cells exposed to 3% plasma from women with pregnancies complicated by preeclampsia resulted in a significant decrease in mitochondrial function with a subsequent significant increase in mitochondrial superoxide generation compared to cells exposed to plasma from women with uncomplicated pregnancies. Real-time PCR analysis showed increased expression of inflammatory markers TNF-α, TLR-9 and ICAM-1 respectively in endothelial cells treated with preeclampsia plasma. MitoTempo is a mitochondrial-targeted antioxidant, pre-treatment of cells with MitoTempo protected against hydrogen peroxide-induced cell death. Furthermore MitoTempo significantly reduced mitochondrial superoxide production in cells exposed to preeclampsia plasma by normalising mitochondrial metabolism. MitoTempo significantly altered the inflammatory profile of plasma treated cells. These novel data support a functional role for mitochondrial redox signaling in modulating the pathogenesis of preeclampsia and identifies mitochondrial-targeted antioxidants as potential therapeutic candidates.

Gastrocnemius mitochondrial respiration: are there any differences between men and women?

Science.gov (United States)

Thompson, Jonathan R; Swanson, Stanley A; Casale, George P; Johanning, Jason M; Papoutsi, Evlampia; Koutakis, Panagiotis; Miserlis, Dimitrios; Zhu, Zhen; Pipinos, Iraklis I

2013-11-01

Work on human and mouse skeletal muscle by our group and others has demonstrated that aging and age-related degenerative diseases are associated with mitochondrial dysfunction, which may be more prevalent in males. There have been, however, no studies that specifically examine the influence of male or female sex on human skeletal muscle mitochondrial respiration. The purpose of this study was to compare mitochondrial respiration in the gastrocnemius of adult men and women. Gastrocnemius muscle was obtained from male (n = 19) and female (n = 11) human subjects with healthy lower-extremity musculoskeletal and arterial systems and normal ambulatory function. All patients were undergoing operations for the treatment of varicose veins in their legs. Mitochondrial respiration was determined with a Clark electrode in an oxygraph cell containing saponin-skinned muscle bundles. Complex I-, II-, III-, and IV-dependent respiration was measured individually and normalized to muscle weight, total protein content, and citrate synthase (CS, index of mitochondrial content). Male and female patients had no evidence of musculoskeletal or arterial disease and did not differ with regard to age, race, body mass index, or other clinical characteristics. Complex I-, II-, III-, and IV-dependent respiration normalized to muscle weight, total protein content, and CS did not statistically differ for males compared with females. Our study evaluates, for the first time, gastrocnemius mitochondrial respiration of adult men and women who have healthy musculoskeletal and arterial systems and normal ambulatory function. Our data demonstrate there are no differences in the respiration of gastrocnemius mitochondria between men and women. Copyright © 2013 Elsevier Inc. All rights reserved.

Metabolic Syndrome and Antipsychotics: The Role of Mitochondrial Fission/Fusion Imbalance

Directory of Open Access Journals (Sweden)

Andrea del Campo

2018-04-01

Full Text Available Second-generation antipsychotics (SGAs are known to increase cardiovascular risk through several physiological mechanisms, including insulin resistance, hepatic steatosis, hyperphagia, and accelerated weight gain. There are limited prophylactic interventions to prevent these side effects of SGAs, in part because the molecular mechanisms underlying SGAs toxicity are not yet completely elucidated. In this perspective article, we introduce an innovative approach to study the metabolic side effects of antipsychotics through the alterations of the mitochondrial dynamics, which leads to an imbalance in mitochondrial fusion/fission ratio and to an inefficient mitochondrial phenotype of muscle cells. We believe that this approach may offer a valuable path to explain SGAs-induced alterations in metabolic homeostasis.

Mitochondrial targeting of human O6-methylguanine DNA methyltransferase protects against cell killing by chemotherapeutic alkylating agents.

Science.gov (United States)

Cai, Shanbao; Xu, Yi; Cooper, Ryan J; Ferkowicz, Michael J; Hartwell, Jennifer R; Pollok, Karen E; Kelley, Mark R

2005-04-15

DNA repair capacity of eukaryotic cells has been studied extensively in recent years. Mammalian cells have been engineered to overexpress recombinant nuclear DNA repair proteins from ectopic genes to assess the impact of increased DNA repair capacity on genome stability. This approach has been used in this study to specifically target O(6)-methylguanine DNA methyltransferase (MGMT) to the mitochondria and examine its impact on cell survival after exposure to DNA alkylating agents. Survival of human hematopoietic cell lines and primary hematopoietic CD34(+) committed progenitor cells was monitored because the baseline repair capacity for alkylation-induced DNA damage is typically low due to insufficient expression of MGMT. Increased DNA repair capacity was observed when K562 cells were transfected with nuclear-targeted MGMT (nucl-MGMT) or mitochondrial-targeted MGMT (mito-MGMT). Furthermore, overexpression of mito-MGMT provided greater resistance to cell killing by 1,3-bis (2-chloroethyl)-1-nitrosourea (BCNU) than overexpression of nucl-MGMT. Simultaneous overexpression of mito-MGMT and nucl-MGMT did not enhance the resistance provided by mito-MGMT alone. Overexpression of either mito-MGMT or nucl-MGMT also conferred a similar level of resistance to methyl methanesulfonate (MMS) and temozolomide (TMZ) but simultaneous overexpression in both cellular compartments was neither additive nor synergistic. When human CD34(+) cells were infected with oncoretroviral vectors that targeted O(6)-benzylguanine (6BG)-resistant MGMT (MGMT(P140K)) to the nucleus or the mitochondria, committed progenitors derived from infected cells were resistant to 6BG/BCNU or 6BG/TMZ. These studies indicate that mitochondrial or nuclear targeting of MGMT protects hematopoietic cells against cell killing by BCNU, TMZ, and MMS, which is consistent with the possibility that mitochondrial DNA damage and nuclear DNA damage contribute equally to alkylating agent-induced cell killing during chemotherapy.

Secreted Human Adipose Leptin Decreases Mitochondrial Respiration in HCT116 Colon Cancer Cells

Science.gov (United States)

Yehuda-Shnaidman, Einav; Nimri, Lili; Tarnovscki, Tanya; Kirshtein, Boris; Rudich, Assaf; Schwartz, Betty

2013-01-01

Obesity is a key risk factor for the development of colon cancer; however, the endocrine/paracrine/metabolic networks mediating this connection are poorly understood. Here we hypothesize that obesity results in secreted products from adipose tissue that induce malignancy-related metabolic alterations in colon cancer cells. Human HCT116 colon cancer cells, were exposed to conditioned media from cultured human adipose tissue fragments of obese vs. non-obese subjects. Oxygen consumption rate (OCR, mostly mitochondrial respiration) and extracellular acidification rate (ECAR, mostly lactate production via glycolysis) were examined vis-à-vis cell viability and expression of related genes and proteins. Our results show that conditioned media from obese (vs. non-obese) subjects decreased basal (40%, prespiration and function in HCT116 colon cancer cells, an effect that is at least partly mediated by leptin. These results highlight a putative novel mechanism for obesity-associated risk of gastrointestinal malignancies, and suggest potential new therapeutic avenues. PMID:24073224

Use the Protonmotive Force: Mitochondrial Uncoupling and Reactive Oxygen Species.

Science.gov (United States)

Berry, Brandon J; Trewin, Adam J; Amitrano, Andrea M; Kim, Minsoo; Wojtovich, Andrew P

2018-04-04

Mitochondrial respiration results in an electrochemical proton gradient, or protonmotive force (pmf), across the mitochondrial inner membrane. The pmf is a form of potential energy consisting of charge (∆ψ m ) and chemical (∆pH) components, that together drive ATP production. In a process called uncoupling, proton leak into the mitochondrial matrix independent of ATP production dissipates the pmf and energy is lost as heat. Other events can directly dissipate the pmf independent of ATP production as well, such as chemical exposure or mechanisms involving regulated mitochondrial membrane electrolyte transport. Uncoupling has defined roles in metabolic plasticity and can be linked through signal transduction to physiologic events. In the latter case, the pmf impacts mitochondrial reactive oxygen species (ROS) production. Although capable of molecular damage, ROS also have signaling properties that depend on the timing, location, and quantity of their production. In this review, we provide a general overview of mitochondrial ROS production, mechanisms of uncoupling, and how these work in tandem to affect physiology and pathologies, including obesity, cardiovascular disease, and immunity. Overall, we highlight that isolated bioenergetic models-mitochondria and cells-only partially recapitulate the complex link between the pmf and ROS signaling that occurs in vivo. Copyright © 2018 Elsevier Ltd. All rights reserved.

Molecular cloning of a peroxisomal Ca2+-dependent member of the mitochondrial carrier superfamily

Science.gov (United States)

Weber, Franz E.; Minestrini, Gianluca; Dyer, James H.; Werder, Moritz; Boffelli, Dario; Compassi, Sabina; Wehrli, Ernst; Thomas, Richard M.; Schulthess, Georg; Hauser, Helmut

1997-01-01

A cDNA from a novel Ca2+-dependent member of the mitochondrial solute carrier superfamily was isolated from a rabbit small intestinal cDNA library. The full-length cDNA clone was 3,298 nt long and coded for a protein of 475 amino acids, with four elongation factor-hand motifs located in the N-terminal half of the molecule. The 25-kDa N-terminal polypeptide was expressed in Escherichia coli, and it was demonstrated that it bound Ca2+, undergoing a reversible and specific conformational change as a result. The conformation of the polypeptide was sensitive to Ca2+ which was bound with high affinity (Kd ≈ 0.37 μM), the apparent Hill coefficient for Ca2+-induced changes being about 2.0. The deduced amino acid sequence of the C-terminal half of the molecule revealed 78% homology to Grave disease carrier protein and 67% homology to human ADP/ATP translocase; this sequence homology identified the protein as a new member of the mitochondrial transporter superfamily. Northern blot analysis revealed the presence of a single transcript of about 3,500 bases, and low expression of the transporter could be detected in the kidney but none in the liver. The main site of expression was the colon with smaller amounts found in the small intestine proximal to the ileum. Immunoelectron microscopy localized the transporter in the peroxisome, although a minor fraction was found in the mitochondria. The Ca2+ binding N-terminal half of the transporter faces the cytosol. PMID:9238007

Complete mitochondrial genome sequences of three bats species and whole genome mitochondrial analyses reveal patterns of codon bias and lend support to a basal split in Chiroptera.

Science.gov (United States)

Meganathan, P R; Pagan, Heidi J T; McCulloch, Eve S; Stevens, Richard D; Ray, David A

2012-01-15

Order Chiroptera is a unique group of mammals whose members have attained self-powered flight as their main mode of locomotion. Much speculation persists regarding bat evolution; however, lack of sufficient molecular data hampers evolutionary and conservation studies. Of ~1200 species, complete mitochondrial genome sequences are available for only eleven. Additional sequences should be generated if we are to resolve many questions concerning these fascinating mammals. Herein, we describe the complete mitochondrial genomes of three bats: Corynorhinus rafinesquii, Lasiurus borealis and Artibeus lituratus. We also compare the currently available mitochondrial genomes and analyze codon usage in Chiroptera. C. rafinesquii, L. borealis and A. lituratus mitochondrial genomes are 16438 bp, 17048 bp and 16709 bp, respectively. Genome organization and gene arrangements are similar to other bats. Phylogenetic analyses using complete mitochondrial genome sequences support previously established phylogenetic relationships and suggest utility in future studies focusing on the evolutionary aspects of these species. Comprehensive analyses of available bat mitochondrial genomes reveal distinct nucleotide patterns and synonymous codon preferences corresponding to different chiropteran families. These patterns suggest that mutational and selection forces are acting to different extents within Chiroptera and shape their mitochondrial genomes. Copyright © 2011 Elsevier B.V. All rights reserved.

Detection of novel polymorphisms in the mitochondrial DNA D-Loop ...

African Journals Online (AJOL)

aghomotsegin

2015-04-08

Apr 8, 2015 ... 1Department of Molecular Biology, Babylon University, Hilla City, Iraq. 2Babylon ... Mitochondrial DNA (mtDNA) is a useful genetic marker for answering .... to you for choosing the project, your enthusiasm for helping us ...

Photosensitized 2-amino-3-hydroxypyridine-induced mitochondrial apoptosis via Smac/DIABLO in human skin cells

Energy Technology Data Exchange (ETDEWEB)

Goyal, Shruti; Amar, Saroj Kumar [Photobiology Laboratory, Systems Toxicology and Health Risk Assessment Group, CSIR — Indian Institute of Toxicology Research (CSIR-IITR), M.G, Marg, Lucknow 226001, Uttar Pradesh (India); Academy of Scientific and Innovative Research (AcSIR), CSIR — IITR, Lucknow 226001 (India); Dwivedi, Ashish; Mujtaba, Syed Faiz; Kushwaha, Hari Narayan; Chopra, Deepti; Pal, Manish Kumar; Singh, Dhirendra [Photobiology Laboratory, Systems Toxicology and Health Risk Assessment Group, CSIR — Indian Institute of Toxicology Research (CSIR-IITR), M.G, Marg, Lucknow 226001, Uttar Pradesh (India); Chaturvedi, Rajnish Kumar [Developmental Toxicology Division, CSIR — Indian Institute of Toxicology Research, P. O. Box 80, M.G. Marg, Lucknow 226001 (India); Ray, Ratan Singh, E-mail: ratanray.2011@rediffmail.com [Photobiology Laboratory, Systems Toxicology and Health Risk Assessment Group, CSIR — Indian Institute of Toxicology Research (CSIR-IITR), M.G, Marg, Lucknow 226001, Uttar Pradesh (India); Academy of Scientific and Innovative Research (AcSIR), CSIR — IITR, Lucknow 226001 (India)

2016-04-15

The popularity of hair dyes use has been increasing regularly throughout the world as per the demand of hair coloring fashion trends and other cosmetic products. 2-Amino-3-hydroxypyridine (A132) is widely used as a hair dye ingredient around the world. We are reporting first time the phototoxicity mechanism of A132 under ambient environmental UV-B radiation. It showed maximum absorption in UV-B region (317 nm) and forms a photoproduct within an hour exposure of UV-B irradiation. Photocytotoxicity of A132 in human keratinocytes (HaCaT) was measured by mitochondrial (MTT), lysosomal (NRU) and LDH assays which illustrated the significant reduction in cell viability. The role of reactive oxygen species (ROS) generation for A132 phototoxicity was established photo- chemically as well as intracellularly. Noteworthy, formation of tail DNA (comet assay), micronuclei and cyclobutane pyrimidine dimers (CPDs) (immunocytochemistry) formation confirmed the photogenotoxic potential of dye. Cell cycle study (sub-G1peak) and staining with EB/AO revealed the cell cycle arrest and apoptosis. Further, mitochondrial mediated apoptosis was corroborated by reduced MMP, release of cytochrome c and upregulation of caspase-3. Release of mitochondrial Smac/DIABLO in cytoplasm demonstrated the caspase dependent apoptotic cell death by photolabile A132 dye. In-addition increased Bax/Bcl2 ratio again proved the apoptosis. Thus, study suggests that A132 induces photogenotoxicity, phototoxicity and apoptotic cell death through the involvement of Smac/DIABLO in mitochondrial apoptosis via caspase dependent manner. Therefore, the long term use of A132 dye and sunlight exposure jointly increased the oxidative stress in skin which causes premature hair loss, damage to progenitor cells of hair follicles. - Highlights: • Photodegradation of A132 and formation of novel photoproduct • Involvement of ROS in A132 phototoxicity • Role of ROS in DNA damage, CPD and micronuclei formation • Release of

Photosensitized 2-amino-3-hydroxypyridine-induced mitochondrial apoptosis via Smac/DIABLO in human skin cells

International Nuclear Information System (INIS)

Goyal, Shruti; Amar, Saroj Kumar; Dwivedi, Ashish; Mujtaba, Syed Faiz; Kushwaha, Hari Narayan; Chopra, Deepti; Pal, Manish Kumar; Singh, Dhirendra; Chaturvedi, Rajnish Kumar; Ray, Ratan Singh

2016-01-01

The popularity of hair dyes use has been increasing regularly throughout the world as per the demand of hair coloring fashion trends and other cosmetic products. 2-Amino-3-hydroxypyridine (A132) is widely used as a hair dye ingredient around the world. We are reporting first time the phototoxicity mechanism of A132 under ambient environmental UV-B radiation. It showed maximum absorption in UV-B region (317 nm) and forms a photoproduct within an hour exposure of UV-B irradiation. Photocytotoxicity of A132 in human keratinocytes (HaCaT) was measured by mitochondrial (MTT), lysosomal (NRU) and LDH assays which illustrated the significant reduction in cell viability. The role of reactive oxygen species (ROS) generation for A132 phototoxicity was established photo- chemically as well as intracellularly. Noteworthy, formation of tail DNA (comet assay), micronuclei and cyclobutane pyrimidine dimers (CPDs) (immunocytochemistry) formation confirmed the photogenotoxic potential of dye. Cell cycle study (sub-G1peak) and staining with EB/AO revealed the cell cycle arrest and apoptosis. Further, mitochondrial mediated apoptosis was corroborated by reduced MMP, release of cytochrome c and upregulation of caspase-3. Release of mitochondrial Smac/DIABLO in cytoplasm demonstrated the caspase dependent apoptotic cell death by photolabile A132 dye. In-addition increased Bax/Bcl2 ratio again proved the apoptosis. Thus, study suggests that A132 induces photogenotoxicity, phototoxicity and apoptotic cell death through the involvement of Smac/DIABLO in mitochondrial apoptosis via caspase dependent manner. Therefore, the long term use of A132 dye and sunlight exposure jointly increased the oxidative stress in skin which causes premature hair loss, damage to progenitor cells of hair follicles. - Highlights: • Photodegradation of A132 and formation of novel photoproduct • Involvement of ROS in A132 phototoxicity • Role of ROS in DNA damage, CPD and micronuclei formation • Release of

Transcription profiling suggests that mitochondrial topoisomerase IB acts as a topological barrier and regulator of mitochondrial DNA transcription.

Science.gov (United States)

Dalla Rosa, Ilaria; Zhang, Hongliang; Khiati, Salim; Wu, Xiaolin; Pommier, Yves

2017-12-08

Mitochondrial DNA (mtDNA) is essential for cell viability because it encodes subunits of the respiratory chain complexes. Mitochondrial topoisomerase IB (TOP1MT) facilitates mtDNA replication by removing DNA topological tensions produced during mtDNA transcription, but it appears to be dispensable. To test whether cells lacking TOP1MT have aberrant mtDNA transcription, we performed mitochondrial transcriptome profiling. To that end, we designed and implemented a customized tiling array, which enabled genome-wide, strand-specific, and simultaneous detection of all mitochondrial transcripts. Our technique revealed that Top1mt KO mouse cells process the mitochondrial transcripts normally but that protein-coding mitochondrial transcripts are elevated. Moreover, we found discrete long noncoding RNAs produced by H-strand transcription and encompassing the noncoding regulatory region of mtDNA in human and murine cells and tissues. Of note, these noncoding RNAs were strongly up-regulated in the absence of TOP1MT. In contrast, 7S DNA, produced by mtDNA replication, was reduced in the Top1mt KO cells. We propose that the long noncoding RNA species in the D-loop region are generated by the extension of H-strand transcripts beyond their canonical stop site and that TOP1MT acts as a topological barrier and regulator for mtDNA transcription and D-loop formation.

Supercomplexes of the mitochondrial electron transport chain decline in the aging rat heart.

Science.gov (United States)

Gómez, Luis A; Monette, Jeffrey S; Chavez, Juan D; Maier, Claudia S; Hagen, Tory M

2009-10-01

Accumulation of mitochondrial electron transport chain (ETC) defects is a recognized hallmark of the age-associated decline in cardiac bioenergetics; however, the molecular events involved are only poorly understood. In the present work, we hypothesized that age-related ETC deterioration stemmed partly from disassociation of large solid-state macromolecular assemblies termed "supercomplexes". Mitochondrial proteins from young and old rat hearts were separated by blue native-PAGE, protein bands analyzed by LC-MALDI-MS/MS, and protein levels quantified by densitometry. Results showed that supercomplexes comprised of various stoichiometries of complexes I, III and IV were observed, and declined significantly (p<0.05, n=4) with age. Supercomplexes displaying the highest molecular masses were the most severely affected. Considering that certain diseases (e.g. Barth Syndrome) display similar supercomplex destabilization as our results for aging, the deterioration in ETC supercomplexes may be an important underlying factor for both impaired mitochondrial function and loss of cardiac bioenergetics with age.

DNA polymerase beta participates in mitochondrial DNA repair

DEFF Research Database (Denmark)

Sykora, P; Kanno, S; Akbari, M

2017-01-01

We have detected DNA polymerase beta (Polβ), known as a key nuclear base excision repair (BER) protein, in mitochondrial protein extracts derived from mammalian tissue and cells. Manipulation of the N-terminal sequence affected the amount of Polβ in the mitochondria. Using Polβ fragments, mitocho......We have detected DNA polymerase beta (Polβ), known as a key nuclear base excision repair (BER) protein, in mitochondrial protein extracts derived from mammalian tissue and cells. Manipulation of the N-terminal sequence affected the amount of Polβ in the mitochondria. Using Polβ fragments......, mitochondrial-specific protein partners were identified, with the interactors mainly functioning in DNA maintenance and mitochondrial import. Of particular interest was the identification of the proteins TWINKLE, SSBP1 and TFAM, all of which are mitochondria specific DNA effectors and are known to function...... in the nucleoid. Polβ directly interacted with, and influenced the activity of, the mitochondrial helicase TWINKLE. Human kidney cells with Polβ knock-out (KO) had higher endogenous mtDNA damage. Mitochondrial extracts derived from heterozygous Polβ mouse tissue and KO cells had lower nucleotide incorporation...

Molecular hydrogen affects body composition, metabolic profiles, and mitochondrial function in middle-aged overweight women.

Science.gov (United States)

Korovljev, D; Trivic, T; Drid, P; Ostojic, S M

2018-02-01

Molecular hydrogen (H 2 ) effectively treats obesity-related disorders in animal models, yet no studies have investigated the effectiveness and safety of H 2 for improving biomarkers of obesity in humans. In this double blind, placebo-controlled, crossover pilot trial, we evaluated the effects of H 2 intervention on body composition, hormonal status, and mitochondrial function in ten (n = 10) middle-aged overweight women. Volunteers received either hydrogen-generating minerals (supplying ~6 ppm of H 2 per day) or placebo by oral administration of caplets for 4 weeks. The primary end-point of treatment efficacy was the change in the body fat percentage from baseline to 4 weeks. In addition, assessment of other body composition indices, screening laboratory studies, and evaluation of side effects were performed before and at follow-up. Clinical trial registration www.clinicaltrials.gov , ID number NCT02832219. No significant differences were observed between treatment groups for changes in weight, body mass index, and body circumferences at 4-week follow-up (P > 0.05). H 2 treatment significantly reduced body fat percentage (3.2 vs. 0.9%, P = 0.05) and arm fat index (9.7 vs. 6.0%, P = 0.01) compared to placebo administration, respectively. This was accompanied by a significant drop in serum triglycerides after H 2 intervention comparing to placebo (21.3 vs. 6.5%; P = 0.04), while other blood lipids remained stable during the study (P > 0.05). Fasting serum insulin levels dropped by 5.4% after H 2 administration, while placebo intervention augmented insulin response by 29.3% (P = 0.01). It appears that orally administered H 2 as a blend of hydrogen-generating minerals might be a beneficial agent in the management of body composition and insulin resistance in obesity.

When to Suspect and How to Diagnose Mitochondrial Disorders?

Science.gov (United States)

Korenev, Sergei; Morris, Andrew A M

2016-10-01

Disorders of the mitochondrial respiratory chain are an exceedingly diverse group. The clinical features can affect any tissue or organ and occur at any age, with any mode of inheritance. The diagnosis of mitochondrial disorders requires knowledge of the clinical phenotypes and access to a wide range of laboratory techniques. A few syndromes are associated with a specific genetic defect and in these cases it is appropriate to proceed directly to an appropriate test of blood or urine. In most cases, however, the best strategy starts with biochemical and histochemical studies on a muscle biopsy. Appropriate molecular genetic studies can then be chosen, based on these results and the clinical picture. Unfortunately, there is currently limited availability of respiratory chain studies in India. Exome sequencing is undertaken increasingly often; without preceding mitochondrial studies, this can lead to misleading results.

Mitochondrial fragmentation in neuronal degeneration: Toward an understanding of HD striatal susceptibility

International Nuclear Information System (INIS)

Cherubini, Marta; Ginés, Silvia

2017-01-01

Huntington's disease (HD) is an autosomal-dominant progressive neurodegenerative disorder that primarily affects medium spiny neurons within the striatum. HD is caused by inheritance of an expanded CAG repeat in the HTT gene, resulting in a mutant huntingtin (mHtt) protein containing extra glutamine residues. Despite the advances in understanding the molecular mechanisms involved in HD the preferential vulnerability of the striatum remains an intriguing question. This review discusses current knowledge that links altered mitochondrial dynamics with striatal susceptibility in HD. We also highlight how the modulation of mitochondrial function may constitute an attractive therapeutic approach to reduce mHtt-induced toxicity and therefore prevent the selective striatal neurodegeneration. - Highlights: • Mitochondrial dynamics is unbalanced towards fission in HD. • Excessive mitochondrial fragmentation plays a critical role in the selective vulnerability of the striatum in HD. • Therapeutic approaches aimed to inhibit mitochondrial fission could contribute to prevent striatal neurodegeneration in HD.

The path from mitochondrial ROS to aging runs through the mitochondrial permeability transition pore.

Science.gov (United States)

Rottenberg, Hagai; Hoek, Jan B

2017-10-01

Excessive production of mitochondrial reactive oxygen species (mROS) is strongly associated with mitochondrial and cellular oxidative damage, aging, and degenerative diseases. However, mROS also induces pathways of protection of mitochondria that slow aging, inhibit cell death, and increase lifespan. Recent studies show that the activation of the mitochondrial permeability transition pore (mPTP), which is triggered by mROS and mitochondrial calcium overloading, is enhanced in aged animals and humans and in aging-related degenerative diseases. mPTP opening initiates further production and release of mROS that damage both mitochondrial and nuclear DNA, proteins, and phospholipids, and also releases matrix NAD that is hydrolyzed in the intermembrane space, thus contributing to the depletion of cellular NAD that accelerates aging. Oxidative damage to calcium transporters leads to calcium overload and more frequent opening of mPTP. Because aging enhances the opening of the mPTP and mPTP opening accelerates aging, we suggest that mPTP opening drives the progression of aging. Activation of the mPTP is regulated, directly and indirectly, not only by the mitochondrial protection pathways that are induced by mROS, but also by pro-apoptotic signals that are induced by DNA damage. We suggest that the integration of these contrasting signals by the mPTP largely determines the rate of cell aging and the initiation of cell death, and thus animal lifespan. The suggestion that the control of mPTP activation is critical for the progression of aging can explain the conflicting and confusing evidence regarding the beneficial and deleterious effects of mROS on health and lifespan. © 2017 The Authors. Aging Cell published by the Anatomical Society and John Wiley & Sons Ltd.