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1
Blaikie, Frances H., and n/a. "Synthesis and characterisation of probes that influence mitochondrial function." University of Otago. Department of Chemistry, 2008. http://adt.otago.ac.nz./public/adt-NZDU20080212.091116.
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The production of reactive oxygen species by mitochondria is implicated in mitochondrial dysfunction associated with a range of diseases and ageing. In addition, reactive oxygen species produced by mitochondria are involved in redox signalling pathways that modulate a number of cell processes. Mitochondria targeted antioxidants comprised of an antioxidant moiety linked to a lipophilic triphenylphosphonium cation have recently been used to decrease oxidative damage to mitochondria and to investigate the involvement of mitochondrial reactive oxygen species in redox signalling. These lipophilic cations are selectively accumulated by mitochondria within cells due to the mitochondria membrane potential. This thesis presents the synthesis and characterization of mitochondria targeted membrane uncoupler, cyclic nitroxide and alkyl thionitrite derivatives, all of which had the potential to influence reactive oxygen species. The biological analysis of these compounds is also presented.
A triphenylphosphonium derivative of the membrane uncoupler 2,4-dinitrophenol (DNP) was anticipated to act as a self regulating protonophore. The DNP moiety would influence the scale of the membrane potential while the triphenylphosphonium cation would respond to the membrane potential. These two factors would combine so that as the membrane potential was dissipated by the uncoupler, the phosphonium cation would be released from the mitochondria and the effect of the uncoupler would thereby be nullified until the membrane potential had increased again. The compound was prepared by nitration of 3-(4-hydroxyphenyl)propyl triphenylphosphonium bromide. An untargeted derivative was also prepared by nitration of 3-(4-hydroxyphenyl)-1-propanol. Unfortunately, while this compound had appropriate acidity and lipophilicity to act as a membrane uncoupler, and did enter mitochondria in response to the membrane potential, it did not act as an uncoupler.
A chemically stable targeted cyclic nitroxide based on Tempol was prepared following literature procedure, although other synthetic routes were also trialled. This compound was shown to concentrate in mitochondria in response to the membrane potential, was reduced by ubiquinol of the coenzyme Q pool, acted as a superoxide dismutase mimetic, and protected membranes against lipid peroxidation.
A mitochondria targeted thionitrite or nitric oxide (NO) donor was anticipated to exhibit an effect on respiration at low oxygen concentrations as the released NO interacted with aspects of the respiratory chain. The alkyl thionitrites were synthesised from appropriate thiol precursors, several of which were prepared. Two targeted alkyl thionitrites were prepared with primary or tertiary carbon arrays next to the thionitrite functionality. Another targeted thionitrite, based on S-nitroso-N-acetylpenicillamine (SNAP), was also prepared. These compounds were difficult to characterise because of issues surrounding their stability. However, modified high resolution positive ion electrospray mass spectrometry in combination with HPLC and NMR was used to identify the compounds and to gauge the purity of the samples. Initial biological investigations verified that the primary alkylthionitrite derivative accumulated in mitochondria, released NO, and had an effect on respiration at low oxygen concentrations.
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Renken, Christian Wolfgang. "The structure of mitochondria /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2004. http://wwwlib.umi.com/cr/ucsd/fullcit?p3141929.
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Jiang, Sirui. "Mitochondrial Dynamic Abnormalities in Alzheimer's Diease." Case Western Reserve University School of Graduate Studies / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=case1536608714970424.
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Shum, Laura C. "Mitochondrial Metabolism in Bone Physiology and Pathology." Thesis, University of Rochester, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10792056.
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Worldwide, 1 in 3 women and 1 in 5 men over age 50 will experience fractures due to a decline in bone quality. Elucidating the mechanisms for declining bone quality can lead to better therapeutics. A vital, yet overlooked aspect of bone health is the role of mitochondrial metabolism in both bone physiology and pathology. We have found that the ability of stem cells to differentiate into bone forming osteoblasts is sensitive to mitochondrial dysfunction, and therefore preserving mitochondrial function is essential to maintaining bone quality. In human patient samples, we found that osteogenesis following a spinal fusion is correlated with mitochondrial function of bone marrow stem cells. While the decline of bone with aging has been well studied, we were the first to find a concomitant decline in mitochondrial function in bone tissue. The most common mechanism of mitochondrial dysfunction is opening of the mitochondrial permeability transition pore (MPTP), a non-selective proteinaceous pore on the inner mitochondrial membrane, positively regulated by the protein cyclophilin D (CypD). Our CypD knockout mouse model has protected mitochondrial function in bone tissue and no decline in bone quality during aging. While we did show that protecting mitochondrial function is beneficial to age-associated bone loss, our ovariectomy model in the CypD knockout mouse did not show any protection. Thus, age-related and estrogen-related bone loss are likely controlled through different mechanisms. Overall, this work has shown the importance of mitochondrial metabolism in bone health and should be further explored as a new avenue for therapeutic interventions.
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Hanson, Bonnie Jean. "Protein based methods for the identification and classification of mitochondrial disorders /." view abstract or download file of text, 2001. http://wwwlib.umi.com/cr/uoregon/fullcit?p3018367.
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Thesis (Ph. D.)--University of Oregon, 2001.Typescript. Includes vita and abstract. Includes bibliographical references (leaves 96-103). Also available for download via the World Wide Web; free to University of Oregon users.
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Oglesbee, Devin. "Improving the diagnosis of mitochondrial diseases : application of monoclonal antibody technologies to NADH:ubiquinone oxidoreductase and cytochrome c oxidase defects /." view abstract or download file of text, 2004. http://wwwlib.umi.com/cr/uoregon/fullcit?p3136436.
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Thesis (Ph. D.)--University of Oregon, 2004.Typescript. Includes vita and abstract. Includes bibliographical references (leaves 113-119). Also available for download via the World Wide Web; free to University of Oregon users.
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Slipetz, Deborah M. "Characterization of mutations in pediatric mitochondrial myopathies." Thesis, McGill University, 1990. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=60101.
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Mitochondrial myopathies are a group of diverse neuromuscular disorders. Defects in electron transport chain (ETC) subunits have been implicated in pediatric and adult onset cases. Skin fibroblasts from four patients were studied to elucidate the biochemical defects.Cells from two patients with ETC complex I deficiency, showed reduced oxidation of alanine with normal oxidation of succinate. Analysis of complex I subunits indicated deficient synthesis of the 20 kDa subunit in the severely affected patient. In the milder patient, subunit abnormalities were not detected.
Fibroblasts from a patient with facioscapulohumeral disease (FSHD), showed reduced oxidation of alanine and succinate through the ETC.
A fourth patient, with decreased activity in several complexes in muscle and liver, was found to have a heteroplasmic mtDNA population in fibroblasts.
These studies exemplify the heterogeneity of mitochondrial myopathies and demonstrate the utility of fibroblasts in the investigation of these disorders.
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Malik, Safarina Golfiani 1963. "Human disorder of energy transduction : molecular pathology." Monash University, Dept. of Biochemistry and Molecular Biology, 2001. http://arrow.monash.edu.au/hdl/1959.1/8335.
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Taylor, Robert William. "Mitochondrial respiratory chain dysfunction in human pathology : investigation, pathogenicity and treatment." Thesis, University of Newcastle Upon Tyne, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.577189.
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The work presented in this thesis comprises 100 peer-reviewed publications, mostly original research papers but some key review articles are included, which highlight my ongoing research in understanding the role of mitochondrial respiratory chain dysfunction and mitochondrial DNA (mtDNA) mutation in human pathologies over a twenty year period, and in no small part have contributed to the development of my laboratory as a national referral centre in the UK for diagnostic biochemical and molecular genetic testing, funded by the NHS Specialist Commissioners. A significant proportion (at least 50%) of all the papers which are included in this application are either first author or senior author publications. Mitochondrial respiratory chain disease exhibits marked clinical and genetic heterogeneity, often requiring the study of clinically-relevant, post-mitotic tissues to make a diagnosis which in many cases is made difficult on account of the peculiarities of mitochondrial genetics. Understanding this phenotypic diversity and elucidating the basic molecular mechanisms leading to cellular dysfunction continues to be challenging, with progress in the development of curative therapies hampered by our inability to manipulate the mitochondrial genome, and difficulties in obtaining alternative models of disease other than patients with pathogenic mtDNA mutations. . In an attempt to submit a cohesive application, the papers have been organised into relevant sections, beginning with general reviews of the clinical, biochemical and molecular features of mitochondrial genetic disease (Section A) followed by sections on the investigation and laboratory diagnosis of mitochondrial disease including epidemiology (Sections 8-0). The largest collection of papers document the molecular investigation of mitochondrial disorders, many describing novel mutations and disease mechanisms associated with both mtDNA- encoded and nuclear mitochondrial genes (Sections E-K). The next section describe studies investigating the role of somatic mtDNA abnormalities in neurodegenerative disease, cancer and ageing pathologies - including marking stem cell populations (Section L) - before a series of original research articles and invited reviews that focus on pharmacological and gene therapy strategies for the treatment of patients with mtDNA disease (Section M).
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van, der Watt George Frederick. "Whole Blood Mitochondrial DNA Depletion in Human Immunodeficiency Virus-Infected Children." Master's thesis, University of Cape Town, 2010. http://hdl.handle.net/11427/2705.
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Background: Nucleoside reverse transcriptase inhibitors (NRTIs) interfere with mitochondrial DNA polymerase gamma causing significant toxic effects, including fatal lactic acidosis. Little is known about mitochondrial DNA (mtDNA) in human immunodeficiency virus (HIV) infected children who face a lifetime exposure to these agents. We performed a cross sectional observation of mtDNA levels in whole blood in a pediatric population to ascertain the relationship between mtDNA, NRTI regimens and parameters of HIV-infection severity. Methods: Whole blood mt:nDNA ratios were determined by real-time PCR in three groups: 27 presumed HIV-negative, 89 HIV-infected, NRTI-treated and 62 HIV-infected treatment-naive children. Multivariate analysis was used to identify variables independently associated with mtDNA depletion. Results: Mean mt:nDNA ratios were lower (P < 0.001) at 77% of control in the HIVinfected antiretroviral treatment (ART) Naïve group and 73% of control in the ART group, but not different between the two HIV-infected groups. Mt:nDNA ratios were negatively associated with age (P = 0.029), HIV status (P < 0.0001) and Log10 of the HIV-1 viral load (P = 0.035) and positively associated with CD4 % (p = 0.032). A 6 stavudine vs zidovudine based regimen was associated with lower but not significant levels of mtDNA (P = 0.1). Conclusions: Depletion of whole blood mtDNA in children is associated independently with HIV-infection and markers of HIV infection severity, and does not improve with either stavudine or zidovudine based ART despite virological control, suggesting that these agents also deplete mtDNA.
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Holowiecki, Andrew. "Catalysis of mitochondrial NADH:NAD+ transhydrogenation in adult Ascaris suum (nematoda)." Bowling Green, Ohio : Bowling Green State University, 2009. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=bgsu1256953439.
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Phillips, Jonathan. "The investigation of axonal pathology in the cerebellum of patients with mitochondrial disease." Thesis, University of Newcastle upon Tyne, 2016. http://hdl.handle.net/10443/3557.
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Cerebellar ataxia affects 68% of adult patients with mitochondrial disease and is associated with progressive loss of co-ordination, impaired balance, and speech difficulties. In these patients, the cerebellum shows numerous neuropathological changes, and a prominent feature is the appearance of axonal torpedoes which represent swollen axons from Purkinje cells. Axonal torpedoes occur in the proximal portion of the Purkinje cell axon projecting into the granular cell layer and are mainly comprised of hyper phosphorylated neurofilament H. Although they have been reported in mitochondrial disease, their significance and contribution to disease is not known. Immunohistochemistry and immunofluorescence was used to characterise and quantify axonal torpedoes in the cerebellums of ten patients with mitochondrial disease and fourteen controls. A triple immunofluorescent assay was developed to reliably quantify the level of respiratory chain protein expression in axonal torpedoes compared to Purkinje cell bodies and their axons. A major limitation of current immunofluorescent techniques is the ability to use very thin brain sections (5μm) due to the intrinsic properties of the tissue causing scattering of light emitted from the fluorophores reducing the resolution of the image. To overcome this limitation, I have optimised the novel clearing technique known as CLARITY (Clear, Lipid-exchanged, Acrylamide-hybridized Rigid, Imaging/immunostaining compatible, Tissue hYdrogel) to use on both mouse and human cerebellar sections from both control individuals and patients. The optimisation of CLARITY has allowed for the use of 250μm thick cerebellar sections to further characterise the morphology of axonal torpedoes in 3D volume as well as determining the degree of axonal changes between patients and controls on a global scale. This study provides a detailed characterisation of axonal pathology that occurs in the cerebellum of patients with mitochondrial disease. The success in optimising the clearing method that produces quality staining of neuronal structures in thick (250μm) cerebellar tissue from both mouse and human tissue will allow for further investigation of changes in the vascular, dendritic or axonal networks in 3D volume on a global scale.
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Chrysostomou, Alexia. "Investigating the contribution of synaptic and vascular pathology to neurodegeneration in mitochondrial disease." Thesis, University of Newcastle upon Tyne, 2016. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.701152.
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Mutations in mitochondrial DNA (mtDNA) lead to a genetically and phenotypically heterogeneous group of human diseases, mitochondrial disorders. Though patients with mtDNA disease present with multisystemic abnormalities, the central nervous system is usually severely affected. Of the neurological deficits, cerebellar ataxia is the most frequently presenting symptom of patients recruited to the UK MRC Mitochondrial Disease Patient cohort, with a prevalence of 70%. Furthermore, stroke-like episodes are prominent, but not restricted, to patients with the Mitochondrial Encephalomyopathy, Lactic Acidosis and Stroke-like episodes (MELAS) syndrome, due to the m.3243A > G point mutation. Both neurological symptoms are associated with pronounced neurodegeneration. The aim of this thesis was to gain further insights into the mechanisms responsible for neuronal loss in patients who manifest with cerebellar ataxia and stroke-like episodes. A reliable, reproducible and quantitative quadruple immunofluorescent technique has been developed that allowed the quantification of respiratory chain protein expression in specific neuronal domains and cellular populations. Furthermore, three-dimensional reconstruction helped examine the structural characteristics of sub-cellular compartments. Close investigation of the intracerebellar microcircuitry provided evidence for respiratory chain protein expression defects in Purkinje cell bodies, dendrites and presynaptic terminals. Altered Purkinje cell innervation of respiratory chain deficient dentate nuclei neurons likely leads to neuronal disinhibition and is accompanied by partially disturbed glutamatergic connectivity to the region. Additionally, respiratory chain deficiencies were detected in the vasculature of vulnerable to stroke-like episodes brain regions (cerebellum, occipital and temporal lobe) in patients harbouring the m.3243A > G point mutation. Preliminary data suggest that stroke-like episode manifestation and cortical lesion development is due to an additive effect between neuronal/interneuronal and vascular pathology. These observations set the basis for studying the impact of mtDNA defects in synaptic, neuronal and vascular health in-vitro and have important implications for identifying good candidates for drug targeting in mitochondrial disease.
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Gonzalez, Serrano Ligia Elena. "Caractérisation de l'ArgRS mitochondriale humaine et contribution à la compréhension des pathologies liées aux mutations des aminoacyl-ARNt synthétases mitochondriales." Thesis, Strasbourg, 2018. http://www.theses.fr/2018STRAJ074/document.
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Les aminoacyl-ARNt synthétases mitochondriales humaines (aaRS mt) sont des enzymes clés de la traduction mitochondriale. Elles catalysent l'aminoacylation des ARNt par les acides aminés correspondent. Des mutations dans leurs gènes sont corrélées à des pathologies avec un large spectre de phénotypes cliniques, mais aux mécanismes moléculaires sous-jacents encore incompris. L'objectif de ce travail de thèse s'intègre dans les axes scientifiques du laboratoire, mais élargit l'intérêt et les connaissance à un système encore peu exploré: l'arginyl-ARNt synthétase mitochondriale (ArgRS mt). Des mutations dans la ArgRS sont liées à une hypoplasie Pontocérébelleuse (PCH6), une pathologie neurodéveloppementale sévère. Le travail de cette thèse s’articule autour de 3 axes : (I) L’analyse des phénotypes cliniques des pathologies liées aux mutations dans les aaRS mt, (II) La caractérisation des propriétéscellulaires de l’ArgRS mt, et (III) L'étude de l’impact de mutations « pathologiques » sur diverses propriétés de l’ArgRS mt. Combinés avec les travaux précédents, les résultats obtenus sont une contribution importante à l'élargissement des connaissances fondamentales des mt aaRSs, et apportent un nouvel éclairage sur le lien entre les mt-aaRSs-mutations et la maladieHuman mitochondrial aminoacyl-tRNA synthetases (mt-aaRSs) are housekeeping enzymes involved in the mitochondrial translation. They catalyze the aminoacylation of tRNAs with their cognate amino acids. Mutations in their nuclear genes are correlated with pathologies with a broad spectrum of clinical phenotypes, but with so far no clear explanations about the underlying molecular mechanism(s). The aim of this PhD work follows the long-standing efforts of the host laboratory but expand the interest and knowledge to an unexplored system: the human mitochondrial arginyl-tRNA synthetase (mt-ArgRS). Mutations in the mt-ArgRS lead to Pontocebellar hypoplasia type 6, a severe neuro-developmental pathology. I thus contributed to i) comprehensively analyze the clinical data reported in pathologies related to mutations on mt-aaRSs, resulting in a categorization according to the affected anatomical system; ii) decipher some cellular properties of the mt-ArgRS; and iii) investigate to impact of disease-associated mutations on mt-aaRSs properties. Combined with previous works, the present results expand the knowledge of the mt-aaRSs, shedding new light on the link between mt-aaRSs-mutations and disease
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Thomas, Kelly Jean. "Pten-induced kinase 1 (PINK1) and its role in mitochondrial function and dynamics." Connect to Electronic Thesis (ProQuest) Connect to Electronic Thesis (CONTENTdm), 2008. http://worldcat.org/oclc/457179676/viewonline.
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Ling, Jiqiang. "Role of phenylalanyl-tRNA synthetase in translation quality control." Columbus, Ohio : Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1212111223.
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Ohland, Derek Paul. "Systematics of cetaceans using restriction site mapping of mitochondrial DNA." Master's thesis, University of Cape Town, 1992. http://hdl.handle.net/11427/27119.
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A phylogenetic study of eleven cetaceans was undertaken using Restriction Endonuclease Maps (RSM) of mitochondrial DNA (mtDNA). One species from the suborder mysticeti (baleen whales) was sampled, and of the ten odontocetes (toothed whales) sampled two were from the family Ziphiidae (beaked whales) and eight were from the family Delphinidae (dolphins) (each representing a different genus). The primarily opportunistically obtained (i.e. from strandings or accidental death in commercial trawl nets) heart tissue generally yielded high quantities of mtDNA which is needed for double digest fragment analysis. The mtDNA extracted from the sampled taxa was cleaved with fifteen different six-base Restriction Enzymes (RE's). Using the three-way method of analysis and aided by the computer program Resolve (Ver. 2.7) (Harley, unpublished), RSM's were constructed. Distance (Neighbor-Joining and Fitsch-Margoliash) and cladistic (Maximum Parsimony and Bootstrap) methods were used to infer phylogenies. The baleen whale was used as an outgroup for the cladistic analysis. Both the distance and both the cladistic methods produced the same single topology, which is concordant with morphologically based classifications. The two differences (within the Delphinidae), viz. Grampus' most basally rooted position and Cephalorhynchus' grouping with the Delphininae are of taxa whose groupings are unresolved in the morphologically based classifications. Using Brown et al's (1979) molecular clock, very recent divergence times at the generic, family and suborder levels were obtained, when compared to fossil based estimates. Using the odontoceti/mysticeti split the base substitution rate of cetacean mtDNA was estimated to be much slower than that of terrestrial mammals (0,3% compared to 1,0% Myr⁻¹). A similarly slow rate was calculated for cetacean nuclear DNA (nDNA) (0,09% Myr⁻¹) (Schlotterer et al, 1991). It remains an unresolved issue as to whether the base substitution rate of cetacean DNA is slower than terrestrial mammals or whether the fossil evidence needs to be reinterpreted. The time of the mysticeti/odontoceti split is palaeontologically uncertain and the suggested monophyletic status of the extant suborders has been questioned, thus making the calculation of cetacean base substitution rate risky. Equally, the incomplete fossil record can lend itself to misinterpretation.
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Pang, Wei Wei. "The role of mitochondria in regulating MAPK signalling pathways during oxidative stress." University of Western Australia. School of Biomedical, Biomolecular and Chemical Sciences, 2006. http://theses.library.uwa.edu.au/adt-WU2007.0026.
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[Truncated abstract] Reactive oxygen species (ROS) have been implicated to play a major role in many pathological conditions including heart attack and stroke. Their ability to modulate the extracellular signal-regulated protein kinase (ERK) and c-Jun Nterminal kinase (JNK) signalling pathways, thereby influencing cellular response has been well-documented. Recent studies implicate a central role for mitochondria in ERK and JNK activation by ROS although the mechanisms remained unresolved. Using Jurkat T-lymphocyte as a cell model, this study demonstrated increased mitochondrial ROS production as a result of decreased mitochondrial complex activities mediated by hydrogen peroxide treatment. This is the first study to show that mitochondria are not essential for activating ERKs, however damaged mitochondria producing ROS can be expected to cause sustained ERK activation . . . This study revealed that JNK and its upstream kinases MKK4, MKK7 and ASK1 are associated with the mitochondria. Furthermore, findings from this study imply that JNK resides in the mitochondrial matrix. This study is the first to demonstrate that mitochondrial JNK can be activated in a cell-free environment by signals originating from the mitochondria. Experimental work using isolated mitochondria demonstrated that mitochondrial JNK can be activated by ROS generated from the mitochondria themselves. Flavin-containing proteins appear to be the main sources of mitochondrial-ROS which signal through redoxsensitive proteins to activate mitochondrial JNK.
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Snell, Cameron Edward. "Mitochondrial modulators of hypoxia-related pathways in tumours." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:33742557-6da8-452d-8374-60ccb9a2dd17.
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The Lon protease is a mitochondrial matrix quality-control protease belonging to the family of AAA+ proteins (ATPases associated with many cellular activities). We had previously found Lon to be upregulated in lung tumours with a non-angiogenic phenotype in a microarray study comparing these to conventional angiogenic tumours. In this project I set out to investigate whether Lon had any role in modulating the hypoxic response of tumour cells. Using a novel monoclonal antibody against Lon, I found that upregulation of Lon was present in breast and lung tumours and that higher levels of Lon are correlated with shorter overall survival in breast cancer patients. Targeting Lon with siRNA and shRNA in tumour cell lines reduced the normoxic and hypoxic stabilisation of HIF-α subunits. This is mediated through a mechanism independent of the activity of HIF-prolyl hydroxylases and independent of any changes in mitochondrial transcription. I found that the pre-imported form of Lon could bind and chaperone VHL in the cytoplasm potentially modulating VHL activity. In cell lines and human tumours, I observed that the proline-hydroxylated form of HIF-1α is induced by hypoxia and the hydroxylated form of HIF-1α is associated with shorter overall survival in breast cancer patients. This observation supports the notion that higher levels of Lon is associated with poor survival by downregulating VHL leading to higher levels of hydroxylated HIF. Finally I show that targeting Lon in cell lines is able to inhibit growth in a cell-line dependent fashion and partially reverses the Warburg effect, increasing oxygen consumption and reducing lactate production. In conclusion, I have demonstrated the broad therapeutic potential of targeting the Lon protease in tumours and highlighted a mechanism of post-hydroxylation HIF-regulation that has not been previously recognised in VHL competent tumours.
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Price, Nathan Loftus. "The Role of SIRT1 in Preventing Mitochondrial Dysfunction with Obesity and Aging." Thesis, Harvard University, 2012. http://dissertations.umi.com/gsas.harvard:10363.
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Mitochondrial function declines with aging and obesity, and has been implicated in the development of many age-related diseases. Caloric restriction (CR) prevents aging and has been shown to induce mitochondrial biogenesis and improve mitochondrial function. These effects may involve increased activity of the \(NAD^+\)-dependent deacetylase SIRT1. Indeed, overexpression of SIRT1 reproduces many of the health benefits of CR including induction of mitochondrial biogenesis by deacetylation and activation of the transcriptional co-activator \(PGC-1\alpha\). Because mitochondria regulate cellular functions important for aging, including, cellular energy production, ROS generation, and apoptosis, determining why mitochondrial function declines with age will improve our understanding of the underlying forces that drive organismal aging. Resveratrol and other SIRT1 activators induce mitochondrial biogenesis and protect against metabolic decline, but whether SIRT1 mediates these benefits is still a matter of debate. To circumvent the developmental defects of germ-line SIRT1 knockouts, we have developed the first inducible system that permits whole-body deletion of SIRT1 in adult mice. Obese mice treated with a moderate dose of resveratrol showed increased mitochondrial biogenesis and function, AMPK activation, and increased \(NAD^+\) levels in skeletal muscle, whereas SIRT1 knockouts displayed none of these benefits. Overexpression of SIRT1 in mice mimicked these effects, demonstrating that SIRT1 is sufficient and necessary for resveratrol to increase mitochondrial function in obese animals, and indicating a central role for SIRT1 in mediating the benefits of this molecule on muscle. Loss of SIRT1 or aging causes mitochondrial dysfunction and decreased expression of mitochondrial-encoded electron transport chain (ETC) components. This decrease in mitochondrial-encoded, but not nuclear-encoded ETC components in SIRT1 knockouts, which we have termed “genome asynchrony”, is independent of \(PGC-1\alpha\). Elevating \(NAD^+\) levels by treatment with the \(NAD^+\) precursor NMN prevented genome asynchrony and mitochondrial dysfunction in aged animals, similar to effects seen with CR. Together these data demonstrate that SIRT1 plays an essential role in preventing genome asynchrony, and that maintaining \(NAD^+\) levels and SIRT1 activity with age may prevent mitochondrial dysfunction. Since SIRT1 is required for NMN or resveratrol to improve mitochondrial function, compounds that activate SIRT1 or elevate \(NAD^+\) may help treat or prevent age-related diseases caused by mitochondrial dysfunction.
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Ho, Lois H. M. "Functional analysis of the promoter regions of alternative oxidase genes from Arabidopsis thaliana." University of Western Australia. School of Biomedical, Biomolecular and Chemical Sciences, 2009. http://theses.library.uwa.edu.au/adt-WU2010.0047.
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[Truncated abstract] Mitochondria are semi-autonomous organelles found in almost all eukaryotic cells to contain more than 1000 different proteins. The majority of these proteins are encoded in the nucleus, translated in the cytosol and imported into mitochondria. The overall aim of this study was to characterise the regulation of nuclear-encoded mitochondrial proteins (NEMP). This was carried out in the plant, Arabidopsis thaliana, using the alternative oxidase (AOX) as a model. Specifically, the aims were to i) determine how regulation of NEMP interact with known regulatory pathways/mechanisms; ii) determine if the pattern of coexpression observed for NEMP are due to co-regulation, and iii) to determine whether mitochondrial retrograde regulatory pathways interact with known chloroplast regulatory pathways. AOX1c is one of five genes encoding AOX in Arabidopsis. It is expressed in a variety of organs and is not induced by stress. Thus, its regulation was characterised in order to gain insight into the regulation of NEMP under normal growth conditions. Analysis of the promoter of AOX1c revealed cis-acting regulatory elements (CAREs) common to both AOX1c from Arabidopsis and AOX2b from soybean. Additionally, Site II elements, previously shown to be involved in the regulation of the proliferating cell nuclear antigen, are present in the upstream promoter region of AtAOX1c and were shown to be strong negative regulators of AtAOX1c expression. AOX1a is a gene encoding AOX that is induced at a transcript level, by many stress treatments. BA signalling and provide evidence of at least one common factor between chloroplastic and mitochondrial retrograde regulatory pathways, i.e. ABI4. ... The above results reveal that the regulation of NEMP are integrated with the mainstream regulatory pathways that control gene expression for a variety of proteins in various locations. Although this is not unexpected, it does raise the question of how mitochondrial function impacts, or feeds back, to alter these pathways, i.e. how mitochondrial retrograde signals affects the regulation of genes encoding proteins in a variety of locations. The observed interaction of mitochondrial and plastid retrograde regulatory pathways at the level of ABI4, suggests that mitochondrial signals have the potential to act as a powerful regulators of many cellular functions. Although interaction between mitochondrial and other organelles at a cellular level has been known for some time, there is still much work left to be done to define the network of molecular interactions that exists to regulate and integrate the expression of NEMP with all other proteins in the cell. This study reveals that interactions also occur at regulatory steps that have to potential to regulate many function in organelles, even if no direct metabolic link exists. However, this study has only begun to uncover these interactions at a molecular level.
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Bowen, Lance Daniel. "Mitochondrial response to hypoxia and assessment of sub-cellular directed DNA repair on mitigating the effects of ROS induced DNA damage /." abstract and full text PDF (free order & download UNR users only), 2006. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3250680.
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Thesis (Ph. D.)--University of Nevada, Reno, 2006."December 2006." Includes bibliographical references. Online version available on the World Wide Web. Library also has microfilm. Ann Arbor, Mich. : ProQuest Information and Learning Company, [2006]. 1 microfilm reel ; 35 mm.
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Taivassalo, Tanja. "Exercise training as therapy for mitochondrial myopathies : physiological, biochemical and genetic effects." Thesis, McGill University, 2000. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=37845.
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Patients with mitochondrial myopathies characteristically exhibit pronounced exercise intolerance, often associated with lactic acidosis, tachycardia and muscle weakness. These clinical features are attributable to impaired electron transport chain function in skeletal muscle. The usual etiology is a primary defect in mitochondrial DNA (mtDNA), where the severity of impairment is presumably linked to the ratio of mutant to wild-type mtDNA. This dissertation presents novel therapeutic approaches to these genetic defects, aimed at attenuating mitochondrial dysfunction and ameliorating the clinical condition by employing exercise training alone or in conjunction with pharmacological therapy. Dichloroacetate (DCA) was administered to augment mitochondrial capacity by activating pyruvate dehydrogenase, thereby decreasing lactic acidosis. Endurance and resistance training paradigms were employed to induce mitochondrial and satellite cell proliferation respectively. The goals were to augment respiratory chain function, increase levels of wild type mtDNA, and reverse effects of chronic inactivity. The effects of these treatments on functional and mitochondrial capacity were defined by changes in: (1) work capacity, oxygen utilization, and circulatory responses during maximal exercise; (2) heart rate and blood lactate during submaximal exercise; (3) recovery kinetics of phosphate-containing metabolites measured using phosphorus magnetic resonance spectroscopy ( 31P MRS); (4) scores on a quality of life questionnaire. The cellular correlates for these indices were defined by changes in: (1) mitochondrial volume, (2) respiratory chain enzyme activity, and (3) levels of mutant/wild-type mtDNA. Although DCA administration alone lowered blood lactate, endurance training was more effective in improving exercise capacity, heart rate and blood lactate, 31P MRS recovery kinetics, and quality of life. Increased mitochondrial volume and respiratory chain function were closely linked
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Tai, Yi-Heng [Verfasser], Martin [Akademischer Betreuer] Kerschensteiner, Thomas [Gutachter] Misgeld, and Mikael [Gutachter] Simons. "Mitochondrial pathology in acute and chronic neuroinflammation / Yi-Heng Tai ; Gutachter: Thomas Misgeld, Mikael Simons ; Betreuer: Martin Kerschensteiner." München : Universitätsbibliothek der TU München, 2020. http://d-nb.info/1241740224/34.
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Wang, Xinglong. "Impaired Balance of Mitochondria Fission and Fusion in Alzheimer Disease." Case Western Reserve University School of Graduate Studies / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=case1228318762.
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Le, Gris Masha. "Mitochondrial protein expression in the developing brain and in pathological conditions." Thesis, University of Oxford, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.670248.
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Pandit, Ashish V. "REGULATION OF MITOCHONDRIAL GENE EXPRESSION IN MULTIPLE SCLEROSIS CORTEX." Kent State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=kent1334214461.
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Sacks, Jessica Erin. "Targeting Mitochondrial Pathways in Obesity and Type 2 Diabetes." Case Western Reserve University School of Graduate Studies / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=case1522935947635474.
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Sauerbeck, Andrew David. "TRICHLOROETHYLENE EXPOSURE AND TRAUMATIC BRAIN INJURY INTERACT AND PRODUCE DUAL INJURY BASED PATHOLOGY AND PIOGLITAZONE CAN ATTENUATE DEFICITS FOLLOWING TRAUMATIC BRAIN INJURY." UKnowledge, 2011. http://uknowledge.uky.edu/gradschool_diss/133.
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The development of Parkinson's disease (PD) in humans has been linked to genetic and environmental factors for many years. However, finding common single insults which can produce pathology in humans has proved difficult. Exposure to trichloroethylene (TCE) or traumatic brain injury (TBI) has been shown to be linked to PD and it has also been proposed that multiple insults may be needed for disease development.
The present studies show that exposure to TCE prior to a TBI can result in pathology similar to early PD and that the interaction of both insults is required for impairment in behavioral function, and cell loss. Following exposure to TCE for 2 weeks there is a 75% impairment in mitochondrial function but it has yet to be shown if the addition of a TBI can make this worse. If the exposure to TCE is reduced to 1 week and combined with TBI a 50% reduction in mitochondrial function is observed following the dual injury which requires both insults. These studies provide further support for the hypothesis that PD may result from a multifactorial mechanism.
It had been established that regional differences exist in mitochondrial function across brain regions. The present studies indicate that previous findings are not likely to be the result of differences in individual mitochondria isolated from the cortex, striatum, and hippocampus. Further analysis of the effect of mitochondrial inhibitors on enzyme activity and oxygen consumption reveal that the different regions of the brain are similarly affected by the inhibitors. These results suggest that findings from previous studies indicating regionally specific deficits following systemic toxin exposure, such as with TCE, are not the result of regional differences in the individual mitochondria.
Given that TBI results in significant dysfunction, finding effective therapeutics for TBI will provide substantial benefits to individuals suffering an insult. Treatment with Pioglitazone following TBI reduced mitochondrial dysfunction, cognitive impairment, cortical tissue loss, and inflammation. These findings provide initial evidence that treatment with Pioglitazone may be an effective intervention for TBI.
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Worgan, Lisa Catherine Women & Children's Health UNSW. "The role of nuclear-encoded subunit genes in mitochondrial complex 1 deficiency." Awarded by:University of New South Wales. Women and Children's Health, 2005. http://handle.unsw.edu.au/1959.4/22307.
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BACKGROUND: Mitochondrial complex I deficiency often leads to a devastating neurodegenerative disorder of childhood. In most cases, the underlying genetic defect is unknown. Recessive nuclear gene mutations, rather than mitochondrial DNA mutations, account for the majority of cases. AIM: Our aim was to identify the genetic basis of complex I deficiency in 34 patients with isolated complex I deficiency, by studying six of the 39 nuclear encoded complex I subunit genes (NDUFV1, NDUFS1, NDUFS2, NDUFS4, NDUFS7 and NDUFS8). These genes have been conserved throughout evolution and carry out essential aspects of complex I function. METHODS: RNA was extracted from patient fibroblasts and cDNA made by reverse transcription. Overlapping amplicons that together spanned the entire coding area of each gene were amplified by PCR. The genes were screened for mutations using denaturing High Performance Liquid Chromatography (dHPLC). Patient samples with abnormal dHPLC profiles underwent direct DNA sequencing. RESULTS: Novel mutations were identified in six of 34 (18%) patients with isolated complex I deficiency. Five patients had two mutations identified and one patient had a single mutation in NDUFS4 identified. All patients with mutations had a progressive encephalopathy and five out of six had Leigh syndrome or Leigh like syndrome. Mutations were found in three nuclear encoded subunit genes, NDUFV1, NDUFS2 and NDUFS4. Three novel NDUFV1 mutations were identified (R386H, K111E and P252R). The R386H mutation was found in two apparently unrelated patients. Four novel NDUFS2 mutations were identified (R221X, M292T, R333Q and IVS9+4A<G). The novel NDUFS4 mutation c.221delC was found in two patients - one in homozygous form and the other heterozygous. Specific genotype and phenotype correlations were not identified. CONCLUSIONS: Nuclear encoded complex I subunit gene mutations are an important contributor to the aetiology of isolated complex I deficiency in childhood. Screening of these genes is an essential part of the investigation of complex I deficiency.
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Schwitlick, Christina [Verfasser]. "The influence of specific mitochondrial polymorphisms on the α-synuclein-induced pathology in a mouse model of Parkinson's disease / Christina Schwitlick." Magdeburg : Universitätsbibliothek, 2015. http://d-nb.info/1078666679/34.
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Szunyogová, Eva. "Understanding the pathogenesis of spinal muscular atrophy by determining the role of survival motor neuron protein in early development." Thesis, University of Aberdeen, 2017. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=237002.
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Spinal Muscular Atrophy (SMA) is caused by mutation or deletion of the Survival Motor Neuron 1 (SMN1), which encodes cell-ubiquitous SMN protein. Although classified as a neuromuscular disease, a range of systemic pathologies is reported in SMA patients. Despite a clear understanding of the genetics, the role of SMN protein in SMA pathogenesis is somewhat unclear, especially in tissues outside the CNS. Here, we describe failed liver development in response to reduced SMN levels, in a Taiwanese mouse model of severe SMA. Molecular analysis revealed significant changes in proteins involved in cell cycling and blood homeostasis including coagulation prior to motor neuron pathology. With SMN being directly associated with some of these proteins, this indicates primary liver pathology in SMA. Study of livers obtained from two other mouse models of SMA; severe SMNΔ7 and intermediate 2B, which have slightly higher SMN levels than Taiwanese SMA mice, also revealed significant overlapping pathologies, suggestive of high intrinsic susceptibility of the liver to SMN decrease. Proteomic study of pre-symptomatic 2B/- liver revealed significant perturbations in mitochondrial bioenergetics, which could account for metabolic defects in SMA patients. Vascular changes can be observed in mouse models of SMA and even skeletal muscle of severe SMA patients. Although Taiwanese SMA liver showed no morphological changes to its vasculature, it does have impairments in several key vascular signaling molecules, including VEGF and Tie-2. Furthermore, we report for the first time significant vascular changes in a zebrafish model of SMA, that could be associated with defective neuronal-vascular signaling and is supported by preliminary findings in the Taiwanese SMA retina. This thesis uncovers perturbations in several clinically relevant signalling pathways directly linked to SMN decrease, independent of the motor neurone pathology. Taken together this work emphasises the importance of a systemic therapy in SMA.
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Breckwoldt, Michael [Verfasser], Thomas [Akademischer Betreuer] Misgeld, Martin [Akademischer Betreuer] Kerschensteiner, Thomas [Akademischer Betreuer] Korn, and Edgar [Akademischer Betreuer] Meinl. "Imaging of mitochondrial redox signals in neuronal physiology and pathology / Michael Breckwoldt. Gutachter: Martin Kerschensteiner ; Thomas Korn ; Edgar Meinl. Betreuer: Thomas Misgeld." München : Universitätsbibliothek der TU München, 2014. http://d-nb.info/1068315911/34.
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Breckwoldt, Michael O. [Verfasser], Thomas [Akademischer Betreuer] Misgeld, Martin [Akademischer Betreuer] Kerschensteiner, Thomas [Akademischer Betreuer] Korn, and Edgar [Akademischer Betreuer] Meinl. "Imaging of mitochondrial redox signals in neuronal physiology and pathology / Michael Breckwoldt. Gutachter: Martin Kerschensteiner ; Thomas Korn ; Edgar Meinl. Betreuer: Thomas Misgeld." München : Universitätsbibliothek der TU München, 2014. http://nbn-resolving.de/urn:nbn:de:bvb:91-diss-20140225-1171922-0-6.
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Schwenzer, Hagen. "Aminoacyl-ARNt synthétases mitochondriales humaines : aspects fondamentaux et contribution à la compréhension de pathologies reliées." Thesis, Strasbourg, 2013. http://www.theses.fr/2013STRAJ045/document.
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Les aminoacyl-ARNt synthetases (aaRS) sont impliquées dans le mécanismes de la traduction. Dans les cellules humaines, il existe deux jeux de gènes nucléaires codant pour les aaRS : un pour les aaRS cytosolique (cyt), le second pour les aaRS mitochondriales (mt). Les aaRS mt sont traduites dans le cytosole, adressées et importées dans la mitochondrie.Mutations dans 9 gènes d’aaRS mt ont été démontrées comme responsables de pathologies mitochondriales. Certaines des mutations n’affectent pas la propriété originelle d’aminoacylation. Il a été proposé que certaines de ces mutations puissent affecter des propriétés alternatives.Alors l’organisation des aaRS cyt est bien étudiée et que des implications dans des fonctions alternatives établies pour certaines d’entre elles, les connaissances quant aux aaRS mt restent parcimonieuses. L’objectif principal de ce manuscrit de thèse est: (i) révéler d’organisation sous-mt de l’AspRS mt; (ii) étendre l’analyse de l’organisation sous-mt à l’ensemble des aaRS mt; et (iii) contribuer à la compréhension de mécanismes moléculaires sous-jacents à certaines pathologies. Ces travaux ouvrent la porte vers d’autres investigations de l’organisation des aaRS à l’intérieur de la mitochondrie. Ces contributions seront utiles à la meilleure compréhension de mécanismes moléculaires sous-jacents à pathologies mitochondrialesAminoacyl-tRNA synthetases (aaRSs) are housekeeping enzymes involved in translation. In human cells, 2 different sets of nuclear genes code for aaRSs. One codes for cytosolic (cyt) aaRSs, and the second one codes for aaRSs of mitochondrial (mt) location. Mt-aaRSs are translated in the cytosol, targeted and imported into mitochondria.Mutations in 9 mt-aaRSs have been described. Some of the mutations do not display significant influence on the housekeeping aminoacylation activity. It has been proposed that those mutations affect alternative functions.Alternate functions have been described for cyt-aaRSs. While the organization of cyt-aaRSs is explored and their involvement into alternate functions established, the properties of the human mt-aaRSs remain unknown. On one site, this thesis integrate mt-AspRS into new functional networks (sub-mitochondrial localization and partnership). On the other site, it expand the view of the sub-mitochondrial organization to the full set of mt-aaRSs and should ultimately shed light into the molecular mechanisms underlying some of the pathologies. These results open the door for additional investigations to gain a complete view about the sub-mitochondrial organization of aaRSs. Those contributions will be of help for the understanding of molecular mechanisms underlying some mitochondrial disorders
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Harland, Micah Thomas. "Neuronal Mitofusin 2 Modulates Neuroinflammation in Acute Systemic Inflammation and Alleviates Pathologies in a Mouse Model for Neurodegenerative Diseases." Case Western Reserve University School of Graduate Studies / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=case1586468876190716.
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Wagner, Gregory Randall. "Identification and characterization of altered mitochondrial protein acetylation in Friedreich's ataxia cardiomyopathy." Thesis, Hindawi Publishing Corporation and Oxford Journals and SAGE Journals, 2011. http://hdl.handle.net/1805/4209.
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Indiana University-Purdue University Indianapolis (IUPUI)Friedreich’s Ataxia (FRDA) is a rare and poorly understood autosomal recessive disease caused by a pathological deficiency of the mitochondrial protein frataxin. Patients suffer neurodegeneration, ataxia, diabetes, and heart failure. In an effort to understand the mechanisms of heart failure in FRDA, we investigated the role of the protein modification acetylation, which is highly abundant on mitochondrial proteins and has been implicated in regulating intermediary metabolism. Using mouse models of FRDA, we found that cardiac frataxin deficiency causes progressive hyperacetylation of mitochondrial proteins which is correlated with loss of respiratory chain subunits and an altered mitochondrial redox state. Mitochondrial protein hyperacetylation could be reversed by the mitochondria-localized deacetylase SIRT3 in vitro, suggesting a defect in endogenous SIRT3 activity. Consistently, frataxin-deficient cardiac mitochondria showed significantly decreased rates of fatty acid oxidation and complete oxidation to carbon dioxide. However, the degree of protein hyperacetylation in FRDA could not be fully explained by SIRT3 loss. Our data suggested that intermediary metabolites and perhaps acetyl-CoA, which is required for protein acetylation, are accumulating in frataxin-deficient mitochondria. Upon testing the hypothesis that mitochondrial protein acetylation is non-enzymatic, we found that the minimal chemical conditions of the mitochondrial matrix are sufficient to cause widespread non-enzymatic protein acetylation in vitro. These data suggest that mitochondrial protein hyperacetylation in FRDA cardiomyopathy mediates progressive post-translational suppression of mitochondrial oxidative pathways which is caused by a combination of SIRT3 deficiency and, likely, an accumulation of unoxidized acetyl-CoA capable of initiating non-enzymatic protein acetylation. These findings provide novel insight into the mechanisms underlying a poorly understood and fatal cardiomyopathy and highlight a fundamental biochemical mechanism that had been previously overlooked in biological systems.
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Van, der Merwe Celia. "An investigation into the role of mitochondrial dysfunction in South African Parkinson’s disease patients." Thesis, Stellenbosch : Stellenbosch University, 2012. http://hdl.handle.net/10019.1/71647.
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Thesis (MScMedSC)--Stellenbosch University, 2012.Bibliography
ENGLISH ABSTRACT: Parkinson’s disease (PD) is a neurodegenerative movement disorder characterized by the loss of dopaminergic neurons in the substantia nigra of the midbrain. Although the aetiology of PD is still not fully understood, it is thought to involve a combination of environmental (such as exposure to pesticides and neurotoxins) and genetic factors. A number of PD-causing genes have been found including SNCA, LRRK2, EIF4G1 and VPS35 (for autosomal dominant forms of PD) and parkin, PINK1, DJ-1 and ATP13A2 (for autosomal recessive forms of PD – arPD). Mutations in the parkin gene are the predominant cause of arPD. Parkin plays a role in the ubiquitin-proteasomal system which degrades damaged and unwanted proteins in the cell and it is also thought to be involved in maintaining healthy mitochondria. Numerous studies have implicated mitochondrial function in the pathogenesis of PD. Therefore the aim of the present study was to investigate the role of mitochondrial dysfunction in PD patients with parkin-null mutations. Four South African PD patients, each harbouring two parkin-null mutations, were recruited for this study. A muscle biopsy was performed for analysis of mitochondrial morphology using histology and transmission electron microscopy (TEM). Skin biopsies were taken, from which fibroblasts were cultured. These fibroblasts were used in i) mitochondrial morphological assessments using TEM, ii) mitochondrial network analysis, iii) functional studies via ROS measurement and iv) analysis of the proteome using a LTQ Orbitrap Velos mass spectrometer. In addition, RNA was isolated from peripheral blood samples for gene expression studies using the RT² Profiler PCR Array (SABiosciences, USA) and the RT² PCR Primer Assay (SABiosciences, USA). Heterozygous family members (carriers) and wild-type controls were also recruited for this study. Results from the histological and TEM analysis from the muscle biopsy observed subtle mitochondrial changes including the presence of type II fibres, atrophic fibres, the presence of lipids, and wrinkling of the sarcolemmal membrane. Enlarged mitochondria were also observed in one patient. TEM analysis on the patient’s fibroblasts observed an increase in the number of electron dense vacuoles, speculated to be autolysosomes. The mitochondrial network in two of the patients’ fibroblasts showed fragmented and dot-like networks which are indicative of damaged mitochondria. An increase in mitochondrial ROS levels was observed in three of the four patients. Expression studies found down-regulation of 14 genes from four of the five mitochondrial complexes and a total of 688 proteins were found only in the control and not in the patient fibroblasts. Some of these proteins are known to be part of the ‘mitochondrial dysfunction’ pathway. Taken together, these results indicate that the absence of parkin results in a number of mitochondrial alterations. Based on these findings, a model of PD was proposed: It is speculated that when parkin is absent, electron transport chain complex genes are down-regulated. This results in impaired oxidative phosphorylation, causing an increase in the production of mitochondrial ROS and subsequent oxidative stress. Mitochondria are then damaged; resulting in the fragmentation of the mitochondrial network. The impaired mitochondria are thus tagged for degradation, causing the recruitment of autolysosomes which engulf the mitochondria via mitophagy. Ultimately, as the compensatory mechanisms fail, this triggers the consequential cascade of cellular apoptotic events. This study has elucidated the effect of parkin on the mitochondria, and can act as a ‘stepping stone’ towards future development of therapeutic strategies and/or biochemical markers that will benefit not only patients with PD but also other neurodegenerative disorders.
AFRIKAANSE OPSOMMING: Parkinson se siekte (PS) is ‘n neurodegeneratiewe bewegings-afwyking gedefineer deur die verlies van dopaminergiese neurone in die substantia nigra van die midde brein. Alhoewel die spesifieke oorsprong van die afwyking nog nie ten volle begryp is nie, word bydraes van beide omgewings faktore (bv. blootstelling aan plaagdoders en neurotoksienes) asook genetiese faktore gespekuleer. Vanuit ‘n genetiese aspek is ‘n aantal gene al geassosieer met PS. Hierdie gene sluit in SNCA, LRRK2, EIF4G1 en VPS35 (vir outosomale dominante vorms van PS) en parkin, PINK1, DJ-1, en ATP13A2 (vir outosomale resessiewe vorms van PS - orPS). Mutasies in die parkin geen is aangedui as die hoof oorsaak van orPS. Parkin speel ‘n rol in die ubiquitine-proteasomale sisteem wat beskadige en ongewensde proteïne binne in die sel verwyder en is verdink om by te dra tot die instandhouding van gesonde mitokondria. Mitokondriese wanfunksionering is ook deur talle studies gewys as ‘n bydraende faktor in die patologie van PS. Die doel van die studie is om ondersoek in te stel tot die spesifieke rol wat mitokondriese wanfunsionering speel in PS pasiënte met parkin-nul mutasies. Vier Suid-Afrikaanse PS-pasiënte, elk met twee parkin-nul mutasies, is gebruik vir die studie. Deur middel van spierbiopsies is monsters verkry vir mitokondriese morfologiese analises met behulp van histologiese en elektron-oordrag mikroskopie tegnieke (TEM). Vel biopsies is ook geneem en fibroblaste is gekweek vir die gebruik in: i) mitokondriese morfologiese assesering; ii) mitokondriese netwerk analiese; iii) funksionele studies waar vlakke van reaktiewe suurstof spesies (ROS) gemeet is; iv) proteoom analiese met behup van ‘n LTQ Orbitrap Velos massa spektrometer. RNA is ook geisoleer vanaf perifere bloedmonsters vir die gebruik in geen-uitdrukkings studies met behulp van ‘n RT² Profiler PCR Array en ‘n RT² Primer Assay. Selle vanaf famielie lede wat heterosigotiese draers is van die mutasie, asook normale (geen parkin mutasie) selle is gebruik as kontroles in die studie. TEM resultate vanaf die spier monsters het subtiele mitokondriese veranderinge getoon. Hierdie sluit in die teenwoordigheid van tipe II vesels, atrofiese vesels, teenwoordigheid van lipiedes, assook waarnemings van rimpeling van die sarcolemmal membraan. Vergrote mitokondrias is ook in een van die pasiënte opgelet. TEM resultate vanaf die fibroblaste het toename in die aantal elektron-digte vakuole vertoon, moontlik geidentifiseer as autolisosome. Gefragmenteerde en onderbreekte mitokondria netwerke is gelet tydens netwerk analiese van die fibroblaste, ‘n indikasie van beskadigde mitokondria. ‘n Toename in mitokondriese ROS vlakke is gevind in drie van die vier pasiënte. Af-regulering van 14 gene, geassosieerd met vier uit die vyf mitokondria komplekse, is verneem tydens die geen-uitdrukkings studie. Saam met dit is ‘n totaal van 688 proteïene geidentifiseer wat slegs teenwoordig is in die kontrole monsters en nie in die pasiënt monsters nie. Hierdie proteïene is almal uitgedruk en betrokke in die mitokondriese wanfunsionerings-weë. Hierdie resultate dui dat die afwesigheid van parkin mitokondriese afwykings tot gevolg het wat kan lei tot die afsterwing van selle. Dit dra ook by tot die vorming van ‘n beter-verstaande siekte-model vir PS: Mutasies in parkin (wat lei tot die afwesigheid van parkin) kan dus moontlik lei tot die af-regulasie van gene geassosieerd met die elektron-vervoer ketting komplekse in die mitokondria. Dit lei tot gebrekkige oksidatiewe fosforilering en veroorsaak ‘n toename in die vorming van ROS, wat dan ‘n toename in oksidatiewe stres binne in die sel tot gevolg het. Uiteindelik lei dit dus tot die beskadiging van die mitokondria wat gepaard gaan met fragmentering van die mitokondriese netwerk. Beskadigde mitokondrias word geetiketeer vir afbraking. Hierdie etiketering aktiveer omringende autophagosome wat die beskadigde mitokondrias dan verwyder deur middel van ‘n verswelgende proses genaamd mitophagy. Dit veroorsaak die aktivering van ‘n aantal gekorreleerde sellulêre prosesse wat lei tot apoptose (afsterwing van die sel). Hierdie studie dra by tot die verklaring van die spesifieke effek wat parkin mutasies het op die funksionering van die mitokondria. Resultate hier lê ook die grondslag vir toekomstige studies met die doel tot die ontwikkeling van terapeutiese strategeë en biochemiese merkers wat kan bydrae tot die genesing van beide pasiënte met PS, asook pasiënte met ander neurodegeneratiewe afwykings.
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Bashir-Tanoli, Sumayia. "Impact of mitochondrial genetic variation and immunity costs on life-history traits in Drosophila melanogaster." Thesis, University of Stirling, 2014. http://hdl.handle.net/1893/21855.
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Immune activation is generally acknowledged to be costly. These costs are frequently assumed to result from trade-offs arising due to the reallocation of resources from other life-history traits to be invested in immunity. Here, I investigated the energetic basis of the costs associated with immune activation in Drosophila melanogaster. I found that immune activation significantly reduced fly fecundity (45%) and also caused a decline in metabolic rate (6%) but had no effect on body weight. To understand the factors behind reduced fecundity and metabolic rate I measured feeding and found that food intake was reduced by almost 31% in immune-challenged D. melanogaster. These findings suggest that fecundity costs of immune activation result not from the commonly accepted resource reallocation hypothesis but probably because resource acquisition is impaired during immune responses. The individuals of any animal population generally vary greatly in their ability to resist infectious disease. This variation arises due to both environmental heterogeneity and genetic diversity. Genetic variation in disease susceptibility has generally been considered to lie in the nuclear genome. Here, for the first time, I explored the influence of mitochondrial genetic (mtDNA) variation on disease susceptibility. I crossed 22 mitochondrial haplotypes onto a single nuclear genome and also studied epistasis interactions between mitochondrial and nuclear genomes (mitonuclear epistasis) by crossing five haplotypes onto five different genetic backgrounds. I found that fly susceptibility to Serratia marcescens was influenced significantly by mtDNA allelic variation. Furthermore, the effect of mitonuclear epistasis on fly susceptibility to S. marcescens was twice as great as the individual effects of either mitochondrial or nuclear genome. However, susceptibility to Beauveria bassiana was not affected by mtDNA allelic variation. These findings suggest the mitochondrial genome may play an important role in host-parasite coevolution. The Mother’s Curse hypothesis suggests that sex-specific selection due to maternal mitochondrial inheritance means that mitochondria are poorly adapted to function in males, resulting in impaired male fitness. Mother’s Curse effects have previously only been studied for two phenotypic traits (sperm-infertility and ageing) and their generality for broader life-history has not been explored. I investigated the impact of mtDNA allelic variation on 10 phenotypic traits and tested whether the patterns of phenotypic variation in males and females conformed to the expectations of the Mother’s Curse hypothesis. I found that seven of the 10 traits were significantly influenced by mtDNA allelic variation. However, there was no evidence that the effects of this variation differed between males and females. I therefore concluded that Mother’s Curse is unlikely to be a general phenomenon, nor to provide a general explanation for sexual dimorphism in life-history traits. Overall, this thesis explored the impacts of immunity costs, mitochondrial genetic variation, mitonuclear epistasis and sex-specific mitochondrial selection on D. melanogaster life-history.
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Weerakoon, Tasmeen Shiny. "Investigation of a putative mitochondrial Twin Arginine Translocation pathway in Arabidopsis thaliana." Miami University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=miami1501256746410956.
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Assaly, Rana. "Protection du myocarde ischémique et pore géant mitochondrial : applications pharmacologiques." Phd thesis, Université Paris Sud - Paris XI, 2011. http://tel.archives-ouvertes.fr/tel-00734466.
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La maladie coronaire d'origine ischémique reste l'une des principales causes de mortalité dans le monde industrialisé. Le traitement de l'ischémie aiguë du myocarde est cependant entré dans une nouvelle ère où la mortalité peut être diminuée de moitié en utilisant des procédures qui permettent un retour rapide du débit sanguin dans la zone ischémique du myocarde, c'est-à-dire la revascularisation. Toutefois, cette reperfusion entraîne par elle-même des complications appelées lésions de la reperfusion qui ont été décrites pour la première fois par Jennings et al., en 1960. Par conséquent, le développement de stratégies cardioprotectrices associées à la reperfusion constitue un besoin majeur en clinique afin d'améliorer la fonction myocardique, de diminuer l'incidence des arythmies, de retarder l'apparition de la mort cardiomyocytaire et de limiter la taille de l'infarctus du myocarde lors de l'ischémie/reperfusion (I/R). La découverte de deux formes principales de mécanismes cardioprotecteurs endogènes, qui consistent en la réalisation de brefs cycles d'I/R appliqués avant l'ischémie (pré-conditionnement ischémique) ou après une longue période d'ischémie au début de la reperfusion (post-conditionnement ischémique), a encouragé la recherche de nouveaux moyens pharmacologiques capables de protéger le myocarde ischémié/reperfusé et a développé nos connaissances sur les bases moléculaires des lésions et de la survie cellulaire au cours des processus d'I/R.L'étude des mécanismes responsables de l'induction de la mort cellulaire a permis de mettre en évidence le rôle prépondérant joué par la mitochondrie et l'augmentation de la perméabilité de ses membranes, induite notamment par la formation/ouverture d'un pore au niveau des points de contacts entre les membranes mitochondriales ; ce pore a été appelé " pore de transition de la perméabilité mitochondriale " (mPTP). L'inhibition de l'ouverture de ce pore apparaît comme une stratégie privilégiée pour protéger le myocarde.De nombreuses études ont montré que les espèces réactives d'oxygène (EROs) jouent un rôle majeur dans les lésions de l'I/R et dans l'ouverture du mPTP. En revanche, il existe peu d'informations claires sur le seuil et la période de production (ischémie et/ou reperfusion) des EROs qui conduisent à l'ouverture du mPTP.Par conséquent, nous avons mis au point un modèle cellulaire d'hypoxie/réoxygénation (H/R) afin d'établir une relation causale entre la production d'EROs, l'ouverture du mPTP et la mort cellulaire tout en explorant le rôle de différents types d'EROs.Ce modèle d'H/R développé sur des cardiomyocytes de rats adultes fraîchement isolés nous a permis de mesurer en temps réel et simultanément la production des EROs, l'ouverture du mPTP et la mort cellulaire. Nous avons montré que la production des EROs débute pendant la période d'hypoxie et que cette production est directement liée à l'augmentation du temps d'hypoxie. Cette production d'EROs à l'hypoxie, plus particulièrement de radicaux hydroxyles et de peroxyde d'hydrogène, a été directement relié, et ceci pour la première fois, à l'ouverture du mPTP et à la mort cellulaire lors de l'H/R.Nous avons utilisé ce modèle pour étudier le mécanisme d'action de deux stratégies pharmacologiques cardioprotectrices, un nouveau ligand de la protéine translocatrice mitochondriale (TSPO), le TRO 40303, et l'activation de la voie RISK (Reperfusion Injury Salvage Kinase) par la morphine. Nous avons ainsi montré que (1) les propriétés cardioprotectrices du TRO40303 sont associées à une inhibition de l'ouverture du mPTP, ce qui n'avait pas pu être démontré au moyen d'expériences réalisées ex vivo et (2) l'activation de la voie RISK par la morphine, qui aboutit à une limitation de la taille d'infarctus associée à une amélioration des fonctions respiratoires mitochondriales, entraîne également une inhibition de l'ouverture du mPTP et un retard de la mort cellulaire des cardiomyocytes isolés soumis à une H/R.La suite logique de ce travail sera de rechercher si l'inhibition du stress oxydant peut constituer un mécanisme commun aux deux stratégies pharmacologiques cardioprotectrices que nous avons décrites en utilisant notre modèle d'H/R. Pour cela, il serait possible d'étendre notre modèle à des animaux génétiquement modifiés pour appréhender plus précisément les phénomènes impliqués dans cette activité antioxydante.A plus long terme, il sera nécessaire d'approfondir nos connaissances sur la production d'EROs pendant l'I/R en recherchant plus spécifiquement l'origine de cette production, notamment le rôle joué par la mitochondrie et l'effet d'autres espèces réactives dans le but de cibler le traitement et de développer de nouvelles stratégies cardioprotectrices.
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Bris, Céline. "Influence de la génétique mitochondriale en pathologie : apport des techniques de séquençage haut débit Deep sequencing shows that oocytes are not prone to accumulate mtDNA heteroplasmic mutations during ovarian ageing Novel NDUFS4 gene mutation in an atypical late-onset mitochondrial form of multifocal dystonia." Thesis, Angers, 2017. http://www.theses.fr/2017ANGE0093.
Full textAbstract:
Les maladies mitochondriales sont des pathologies fréquentes du métabolisme caractérisées par une forte hétérogénéité clinique et génétique, notamment par la dépendance à 2 génomes, nucléaire (ADNn) et mitochondrial (ADNmt), et le concept d’hétéroplasmie (HT). L’objectif de ce travail de thèse a été de développer une stratégie d’analyse de l’ADNmt par séquençage haut-débit (NGS), puis de l’appliquer à l’étude des maladies mitochondriales et des pathologies liées au vieillissement : glaucome à angle ouvert (GPAO) et vieillissement ovarien précoce. Après validation des performances de notre stratégie NGS pour la détection et la quantification des variations de l’ADNmt, nous avons confirmé l’intérêt de l’analyse systématique de la totalité de l’ADNmt avec l’identification de nouveaux variants et l’utilisation de cellules uroépithéliales pour le diagnostic des maladies mitochondriales. Cependant, ces progrès génèrent de nouveaux défis dont l’interprétation des faibles HT et la priorisation des variants de signification inconnue. Pour les pathologies liées au vieillissement, nous avons mis en évidence le possible rôle protecteur des haplogroupes T et H chez les femmes, respectivement dans la survenue et la sévérité du GPAO, suggérant une modulation de l’influence de l’ADNmt par le genre et donc l’importance de la stratification par sexe dans les études d’association. En revanche, nous n’observons pas d’accumulation d’anomalies de l’ADNmt dans le vieillissement ovarien précoce. En perspective, nous rapportons l’identification d’une mutation de l’ADNn dans un phénotype atypique, rappelant la complexité de l’étude des pathologies mitochondriales, du fait de ce double génomeMitochondrial diseases are common metabolic disorders characterized by strong clinical and genetic heterogeneity, in particular due to the dependence on 2 genomes, nuclear (nDNA) and mitochondrial DNA (mtDNA), and the concept of mitochondrial heteroplasmy. The purpose of this work was to develop a strategy for the analysis of the mtDNA through next-generation sequencing (NGS), and then to apply it to the study of mitochondrial diseases and those related to aging: primary open-angle glaucoma (POAG) and ovarian aging. After validating the performances of our NGS strategy for the detection and quantification of mtDNA variations, we confirmed the power of systematic analysis of the whole mitochondrial genome with the use of uroepithelial cells for mitochondrial diseases diagnosis and the identification of novel mtDNA variants. However, these advances generate new challenges such as the interpretation of low percentages of mtDNA mutations or the prediction of the pathogenicity of new variants. For aging-related diseases, we have identified the possible protective role of the mitochondrial haplogroups T and H in women, respectively in the occurrence and severity of POAG, suggesting that mtDNA influence is drivenby gender, and thus the importance of gender stratification for association studies. By contrast, we did not observe any accumulation of mtDNA abnormalities in early ovarian aging. In perspective, we report the identification of a nDNA mutation in an atypical phenotype, highlighting the complexity of mitochondrial diseases diagnosis, due to this double genome
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Carneiro, Lionel. "Détection hypothalamique de l'hyperglycémie : rôle de la dynamique mitochondriale dans la signalisation par les espèces actives de l'oxygène." Phd thesis, Université de Bourgogne, 2011. http://tel.archives-ouvertes.fr/tel-00689166.
Full textAbstract:
L'homéostasie énergétique se définit comme le maintien de l'équilibre entre les apports et les dépenses d'énergie. La régulation nerveuse de cet équilibre est principalement assurée par l'hypothalamus. Il existe dans cette structure des neurones spécialisés dont l'activité électrique est modifiée par des signaux nerveux, métaboliques et hormonaux.Nous avons travaillé sur la détection du glucose dans cette structure, qui permet l'élaboration d'une réponse adaptée en termes de prise alimentaire et de contrôle du métabolisme. Lors de cette détection, l'utilisation du glucose conduit à la formation d'Espèces Actives de l'Oxygène d'origine mitochondriale (mEAOs) par la chaîne respiratoire mitochondriale (CRM), constituant une signalisation redox indispensable aux réponses physiologiques. De récentes études in vitro (cultures de myoblastes, hépatocytes) ont par ailleurs mis en évidence le rôle de la dynamique mitochondriale, qui contrôle la morphologie des mitochondries par des mécanismes de fission et de fusion, sur la production de mEAOs induite par une hyperglycémie. Cette dernière déclenche la fission des mitochondries de façon concomitante à la production de mEAOs. En revanche, le blocage de la fission empêche la production de mEAOs lors de l'hyperglycémie dans ces cultures. Ces études suggéraient donc que la fission soit déclenchée par l'hyperglycémie et permette alors la production de mEAOs. Mon projet de thèse a consisté à déterminer l'implication de la dynamique mitochondriale dans la signalisation mEAOs lors de la détection hypothalamique du glucose. Nos résultats nous ont permis de mettre en évidence, dans un premier temps, un adressage de la protéine de fission DRP1 à la mitochondrie dans l'hypothalamus lors d'une hyperglycémie cérébrale, évènement nécessaire au déclenchement de la fragmentation des mitochondries. Cette fragmentation est confirmée en imagerie où l'analyse morphologique montre des mitochondries plus petites, plus sphériques et moins allongées que celles des témoins. Dans un deuxième temps, nous avons déterminé l'implication de cette fission mitochondriale dans la détection hypothalamique du glucose. Son importance a pu être évaluée en bloquant la fission des mitochondries par l'inhibition de l'expression de la protéine de fission DRP1 spécifiquement dans le VMH, par interférence ARN. Cette stratégie nous a permis d'obtenir une inhibition de l'expression de DRP1 de près de 80%, 72h après l'injection. Cette inhibition est localisée au VMH et a pour conséquence une élongation des mitochondries qui présente un réseau mitochondrial plus filamenteux. L'étude du phénotype des animaux a mis en évidence une hyperphagie associée à l'inhibition de la fission mitochondriale dans le VMH. Cette hyperphagie n'entraine cependant aucune modification du poids corporel. Ceci suggère une augmentation des dépenses énergétiques chez ces animaux. De plus, ils présentent une perte de sensibilité hypothalamique au glucose qui conduit à un défaut du contrôle nerveux de la sécrétion d'insuline, ainsi qu'à une perte de l'effet satiétogène du glucose lors d'un test de réalimentation. Nous montrons que cette perte de sensibilité au glucose est due à un défaut de production hypothalamique des mEAOs en réponse au glucose, production qui est nécessaire à la signalisation responsable des réponses effectrices. Ce défaut de production de mEAOs est associé à un dysfonctionnement de la CRM. L'ensemble de ce travail permet donc de montrer pour la première fois, in vivo, que la fission mitochondriale est indispensable à la production hypothalamique de mEAOs lors d'une hyperglycémie cérébrale. Cette production est nécessaire au déclenchement du contrôle nerveux permettant d'une part la sécrétion d'insuline et d'autre part le rassasiement induit par le glucose intra-hypothalamique.
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Taylor, Matthew A. "The effect of varying times of ischemia on the levels of glutathione in the cytosol and mitochondria of the rat kidney." Virtual Press, 2002. http://liblink.bsu.edu/uhtbin/catkey/1236375.
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Ischemia caused by the disruption of blood flow results in kidney damage and dysfunction. This study investigated the effects of 30, 60 or 120 minutes of renal ischemia on the levels of glutathione (GSH), the major antioxidant inside cells. Kidneys from anesthetized female Lewis rats (9 months old) were clamped to induce ischemia and then homogenized and separated into cytosolic and mitochondria fractions by differential centrifugation. The levels of GSH and oxidized glutathione (GSSG) in the fractions were measured spectrophotometrically or by capillary electrophoresis. A significant reduction in GSH levels in the cytosol and mitochondria was seen only after the kidney underwent 60 minutes of ischemia. The significant decrease in GSH was accompanied by an increase in the GSSG/GSH ratio and an alteration in the glutathione redox ratio (i.e., GSH/total glutathione). This study demonstrates that an ischemic time of 60 minutes or longer is necessary to cause depletion of GSH levels in the rat kidney.Department of Physiology and Health Science
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Bedoya, Felipe. "Identification and Characterization of Mitochondrial Genome Concatemers in AIDS-Associated Lymphomas and Lymphoma Cell Lines." [Tampa, Fla] : University of South Florida, 2009. http://purl.fcla.edu/usf/dc/et/SFE0003030.
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Montaigne, David. "Pathologie du métabolisme énergétique cardiaque induite par la doxorubicine." Lille 2, 2010. http://www.theses.fr/2010LIL2S018.
Full textAbstract:
La doxorubicine est une anthracycline utilisée largement dans le traitement des cancers du sein et des hémopathies malignes, mais présente une cardiotoxicité qui en limite l’utilisation. Cette toxicité est attribuée en grande partie aux conséquences des anthracyclines sur le métabolisme énergétique cardiaque : les anthracyclines produisent au niveau cellulaire des espèces radicalaires de l’oxygène à l’origine d’une inhibition de la chaîne respiratoire mitochondriale, d’une dissipation du potentiel de membrane mitochondriale, d’une surcharge calcique mitochondriale. L’hypothèse de notre travail est que l’inhibition de l’ouverture du pore de transition de perméabilité mitochondrial (mPTP) puisse diminuer les altérations du métabolisme cardiaque et la dysfonction contractile observées dans des modèles d’exposition aigue et sub-aigue à la doxorubicine. L’étude a été réalisée sur des préparations de myocarde murin et humain. Nous avons montré que la doxorubicine altère rapidement les fonctions contractile et métabolique de préparations myocardiques contractiles humaine et murine à des concentrations de l’ordre de celles observées chez le patient. Ces altérations pouvaient être en partie expliquées par une ouverture du pore de transition de perméabilité mitochondrial comme en témoigne la cardioprotection offerte par la ciclosporine A dans ces modèles d’exposition aiguë. Nous avons également montré dans des modèles sub-aigue et chronique de cardiotoxicité de la doxorubicine que l’administration de ciclosporine A (à l’inverse du FK506) améliore la survie, la fonction contractile cardiaque et l’homéostasie mitochondriale en terme de potentiel de membrane mitochondrial, respiration mitochondrial, capacité d’accumulation du calcium, équilibre entre fusion et fission itochondriales. Ainsi, l’ensemble de nos résultats conforte sur myocarde murin et humain les données de la littérature quant au rôle important du pore de transition mitochondrial et des altérations du métabolisme énergétique dans la physiopathologie de la cardiotoxicité des anthracyclines. De plus, la ciclosporine A apparaît capable de préserver la fonction contractile des coeurs exposés aux anthracyclines, ainsi que la capacité du réseau mitochondrial à produire de l’énergie. Nous pensons que ces travaux permettent d’envisager la mise en place d’une étude de cardioprotection par la ciclosporine A vis à vis de la toxicité de la doxorubicine dans un essai clinique de type « proof of concept ».
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Beauvais, Geneviève. "Molecular and cellular bases for the protective effects of dopamine D1 receptor antagonist, SCH23390, against methamphetamine-induced neurotoxicity in the rat brain." Phd thesis, Université René Descartes - Paris V, 2012. http://tel.archives-ouvertes.fr/tel-00691924.
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Methamphetamine (METH) is a potent psychostimulant known to cause cognitive abnormalities and neurodegenerative changes in the brains of METH abusers. One approach for developing therapies for METH abuse is to understand the molecular mechanisms of toxicity of the drug. Investigations in our laboratory and elsewhere have shown that single intraperitoneal injections of METH (30-40 mg/kg of body weight) can cause damage to striatal and cortical monoaminergic systems and induce neuronal apoptosis in the striatum of rodents via activation of endoplasmic reticulum (ER) and mitochondrial death pathways. Hence, the purpose of this thesis was to investigate if toxic binge METH injections can cause ER- and mitochondria-induced stress in the rat striatum. Recent studies have suggested that dopamine (DA) D1 and D2 receptors might mediate neuronal apoptosis in the striatum after single toxic METH doses. We therefore hypothesized that signaling through these two types of DA receptors might activate toxic effects of the binge METH regimen. The role of DA D1 or D2 receptors in METH-induced cell death pathways was thus examined by using pharmacological inhibitors of these receptors. In this dissertation, I report that binge METH regimen caused differential changes in immediate early genes (IEGs) that are known to influence synaptic changes in the brain. METH-induced changed in the expression of the IEGs were dependent on DA D1 receptor stimulation. The second study examined the effects of binge METH on the expression of ER stress- and mitochondrial dysfunction-responsive genes. Pretreatment with the DA D1 receptor antagonist, SCH23390, caused complete inhibition of METH-induced ER and mitochondrial stresses whereas the DA D2 receptor antagonist, raclopride, provided only partial blockade. SCH23390 also blocked METH-induced hyperthermia whereas raclopride failed to do so. Interestingly, both antagonists attenuated METH-induced dopaminergic and serotonergic deficits in the striatum. Moreover, SCH23390 but not raclopride blocked METH-induced serotonergic deficits in cortical tissues. I also found that METH treatment induced upregulation of activin βA mRNA, increased TGF-β and phosphorylated Smad2 proteins in the rat striatum. SCH23390 pretreatment completely blocked all these effects whereas raclopride did not block METH-induced increases in TGF-β expression.
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Mary, Arnaud. "Implications de la signalisation de la protéine kinase activée par l’AMP (AMPK) dans les dysfonctions mitochondriales, la pathologie amyloïde et Tau, et la neuroinflammation dans la maladie d’Alzheimer." Electronic Thesis or Diss., Université Côte d'Azur, 2022. http://theses.univ-cotedazur.fr/2022COAZ6001.
Full textAbstract:
La maladie d’Alzheimer (MA) est la pathologie neurodégénérative la plus répandue dans le monde. L’échec des traitements ciblant l’amyloïde beta (Aβ), un catabolite de la protéine précurseur de l’amyloïde (APP), souligne le caractère multifactoriel de cette pathologie. Ainsi, les défauts précoces de la structure et de la fonction des mitochondries et la neuroinflammation sont impliqués dans le développement de la MA. Différentes études décrivent l’AMPK (AMP-activated protein kinase) comme étant un acteur majeur de l'homéostasie mitochondriale notamment via l’élimination des mitochondries altérées par mitophagie et dans la régulation de la neuroinflammation.L'hypothèse centrale de mon projet postule qu'outre le peptide Aβ, d'autres catabolites de l'APP, les fragments C-terminaux (APP-CTFs) peuvent contribuer aux dysfonctions mitochondriales et aux défauts de la mitophagie, et que la modulation de l’AMPK pourrait avoir un impact bénéfique dans le contexte de la MA.Ma thèse est structurée en deux objectifs spécifiques :Axe 1. Étude de la contribution des APP-CTFs dans les défauts de la structure et de la fonction des mitochondries et de la mitophagie dans la MA. Nous avons observé une accumulation des APP-CTFs dans la mitochondrie des cellules de neuroblastomes humains exprimant de façon stable l’APP portant la double mutation suédoise (SH-SY5Y-APPswe), ou le fragment APP-CTFβ : C99 (SH-SY5Y-C99) entraînant une altération de la morphologie des mitochondries, une augmentation de la production d’espèces réactives de l’oxygène (ROSmit) et un blocage de la mitophagie. Ces effets toxiques ont été confirmés chez les souris présymptomatiques 3xTgAD (APPswe, TauP301L, PS1 (M146V)) et des souris exprimant le fragment C99 par une approche virale, et sont exacerbés (in vitro et in vivo) suite à l’inhibition de la γ-sécrétase, bloquant la production du peptide Aβ et accumulant les APP-CTFs. Enfin, l’analyse des nécropsies de cerveaux de patients humains diagnostiqués avec une forme sporadique de la MA, a montré une accumulation des APP-CTFs dans les mitochondries, corrélant avec un défaut du processus mitophagique. Ainsi, cibler l’accumulation précoce de ces APP-CTFs et la dysfonction mitochondriale pourraient représenter de nouvelles cibles thérapeutiques dans le contexte de la MA.Axe 2. Étude de l'impact de la modulation de la cascade de signalisation de l'AMPK dans le contexte de la MA. Nous avons observé une répression de la cascade AMPK-ULK1 dans les nécropsies de lobes temporaux de patients Alzheimer sporadiques, dans les modèles d’étude de la MA in vitro (SH-SY5Y-APPswe et SH-SY5Y-C99), et chez les souris symptomatiques 3xTgAD. Nous avons démontré que l’inhibition pharmacologique de l’AMPK augmente l’accumulation des APP-CTFs, exacerbe les défauts de la structure des mitochondries, provoque une hyperpolarisation de la membrane mitochondriale et une augmentation de la production de ROSmit, et inhibe la mitophagie dans les modèles in vitro. L’inhibition pharmacologique de l’AMPK affecte également la maturation des épines dendritiques ex vivo (coupes organotypiques d’hippocampes exprimant l’APPswe par une approche virale). A l’inverse, l’activation pharmacologique de l’AMPK permet de réduire le dysfonctionnement mitochondrial (in vitro), de favoriser la maturation des épines dendritiques (ex vivo). Nous avons confirmé ces observations par une approche génétique en exprimant des constructions AMPK mutées (formes constitutive active et dominante-négative). De façon importante, l’activation pharmacologique de l’AMPK in vivo a permis de réduire la pathologie Aβ et Tau, ainsi que la neuroinflammation et les défauts d’apprentissage chez les souris 3xTgAD symptomatiques. Ainsi, la stimulation de l’AMPK pourrait représenter une nouvelle piste thérapeutique réduisant plusieurs paradigmes associés à la MAAlzheimer’s disease (AD) is the most common neurodegenerative disease in the world. Failures of candidate treatments targeting the beta amyloid (Aβ), a catabolite originating from the amyloid precursor protein (APP), highlight the multifactorial nature of this pathology. Hence, the early defects of mitochondrial structure and functions, and the neuroinflammation are implicated in AD development. Several studies describe the AMPK (AMP-activated protein kinase) as a master regulator of mitochondrial homeostasis, notably via the elimination of damaged mitochondria by mitophagy, and also of neuroinflammation. The central hypothesis of my thesis postulates that, besides the Aβ peptide, other APP catabolites, the C-terminals fragments (APP-CTFs) can contribute to mitochondrial dysfunctions and that the modulation of the AMPK could hold beneficial effects in AD.My thesis is structured into two specific objectives:Axe 1. Study of the APP-CTFs contribution to the alterations of mitochondria structure, functions, and mitophagy in AD. We have observed an accumulation of APP-CTFs in mitochondria of human neuroblastoma cells stably expressing APP with the double Swedish mutation (SH-SY5Y-APPswe), or the APP-βCTF: C99 (SH-SY5Y-C99), causing an alteration of mitochondria morphology, an increase reactive oxygen species (ROSmit) production, and a blockade of mitophagy. These toxic effects were confirmed in presymptomatic 3xTgAD mice (APPswe, TauP301L, PS1 (M146V)) and in mice expressing the C99 fragment via a lentiviral approach and were exacerbated (in vitro and in vivo) following the inhibition of the γ-secretase, blocking the Aβ production and accumulating APP-CTFs. Finally, we have reported a mitochondrial accumulation of APP-CTFs in the temporal lobes necropsies of sporadic AD patients correlating with a defective mitophagic phenotype. Hence, targeting the early APP-CTFs accumulation and mitochondrial dysfunctions could constitute promising novel therapeutic targets in the AD context.Axe 2. Study of the impact of AMPK signaling cascade modulation in AD. We have observed a defective AMPK-ULK1 cascade in the temporal lobes necropsies of sporadic AD patients, in in vitro AD study models (SH-SY5Y-APPswe and -C99) and in symptomatic 3xTgAD mice. Afterward, we have demonstrated that the pharmacological inhibition of AMPK enhances APP-CTFs accumulation, worsen mitochondria structure alterations, triggers mitochondria membrane hyperpolarization, increases ROSmit production, and inhibits mitophagy in vitro. Pharmacological AMPK blockade also alters the dendritic spine maturation ex vivo (organotypic hippocampal slices lentivirally expressing APPswe). Oppositely, the pharmacological activation of AMPK alleviates mitochondria dysfunctions in vitro and favors the dendritic spine maturation ex vivo. We confirmed these observations using a genetic approach by expressing mutated AMPK constructs (constitutive active and dominant negative forms). Importantly, pharmacological activation of AMPK reduces Aβ and Tau pathologies, as well as neuroinflammation and learning impairments in symptomatic 3xTgAD mice. Overall, the stimulation of AMPK could stand as a new therapeutic avenue to alleviate AD pathogenesis
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Marmolino, Daniele. "Alterations of mitochondrial biogenesis and alterations of mitochondrial antioxidant defense in Friedreich's ataxia." Doctoral thesis, Universite Libre de Bruxelles, 2011. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209972.
Full textAbstract:
Friedreich’s ataxia (FRDA) is an autosomal recessive inherited disorder affecting approximately 1 every 40,000 individuals in Western Europe, is characterized by progressive gait and limb ataxia, dysarthria, areflexia, loss of vibratory and position sense, and a progressive weakness of central origin. Additional features particularly include an hypertrophic cardiomyopathy that can cause premature death. A large GAA repeat expansion in the first intron of the FXN gene is the most common mutation underlying FRDA. Patients show severely reduced levels of the FXN-encoded mitochondrial protein frataxin.Frataxin function is not yet completely elucidated. In frataxin deficiency conditions abnormalities of iron metabolism occur: decreased activities of iron-sulfur cluster (ISC) containing proteins, accumulation of iron in mitochondria and depletion in the cytosol, enhanced cellular iron uptake, and, in some models, reduced heme synthesis.
Evidence of oxidative stress has also been found in most though not all models of frataxin deficiency. Accordingly, yfh1-deficient yeast and cells from FRDA patients are highly sensitive to oxidants. Respiratory chain dysfunction further aggravate oxidative stress by increasing leakage of electrons and the formation of superoxide. Frataxin deficient cells not only generate more free radicals, but, they also show a reduced ability to mobilize antioxidant defenses, in particular to induce superoxide dismutase 2 (SOD2).
Peroxisome proliferator-activated receptor (PPAR) isoform-gamma play a key role in numerous cellular functions and is a key regulator of mitochondrial biogenesis and of the ROS metabolism. Recruitment of the PPAR coactivator-1a (PGC-1a) mediates many effects of the PPAR-γ activation.
In a first work we assessed the potential beneficial effects of a potent PPAR-gamma agonist on frataxin expression in primary fibroblasts from healthy controls and FRDA patients, and Neuroblastoma cells. We used the APAF molecule (1-0-hexadecyl-2-azelaoyl-sn-glycero-3-phosphocoline; C33H66NO9P). Our results show that this compound is able to increase frataxin amount both at transcriptional and post-transcriptional level. At a dose of 20µM frataxin mRNA significantly increases in both controls (p=0.03) and FRDA patients (p=0.002) fibroblasts (1). The finding was confirmed in Neuroblastoma cells (p=0.042). According to previous publications APAF, as others PPAR-gamma agonists is able to up-regulate PGC-1a transcription.
In a second part of the study we investigate the role of the PPAR-gamma/PGC-1a pathway in the pathogenesis of FRDA. We performed a microarray analysis of heart and skeletal muscle in a mouse model of frataxin deficiency and we found molecular evidence of increased lipogenesis in skeletal muscle and alteration of fiber-type composition in heart, consistent with insulin resistance and cardiomyopathy, respectively. Since the PPAR-gamma pathway is known to regulate both processes, we hypothesized that dysregulation of this pathway could play a key role in frataxin deficiency. We confirmed this by showing a coordinate dysregulation of Pgc1a and the transcription factor Srebp1 in cellular and animal models of frataxin deficiency, and in cells from FRDA patients, who have marked insulin resistance. Particularly, PGC-1a was found significantly reduced (2) in primary fibroblasts and lymphocytes from FRDA patients (p<0.05). Furthermore, PGC-1a mRNA levels strongly correlate with frataxin relative mRNA levels (r2=0.9, p<0.001). According to this observation, in C2C12 myoblasts, PGC-1a and a reporter gene under the control of the PGC-1a promoter are rapidly down-regulated (p<0.05) when frataxin expression is inhibited by an shRNA in vitro. To further investigate this relation, we then generate PGC-1a deficient fibroblasts cells using a specific siRNA; at 72 hours of transfection frataxin was found down-regulate (p<0.05) in control cells.
Taken together those data indicate that some mechanism directly links an early effect of frataxin deficiency with reduced PGC-1a transcription in this cell type, and presumably in other cells that also down-regulate PGC-1α when frataxin levels are low.
Finally, since PGC-1a has also emerged as a key factor in the induction of many antioxidant programs in response to oxidative stress, both in vivo and in vitro, in particular in neurons, we tested whether the PGC-1a down-regulation occurring in FRDA cells could be in part responsible for the blunted antioxidant response observed in frataxin deficiency.
Using primary fibroblasts from FRDA patients we found reduced SOD2 levels (p<0.05), according to PGC1&
Doctorat en Sciences biomédicales et pharmaceutiques
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Haut, Sandrine. "Place de la biologie moléculaire dans le diagnostic des cytopathies mitochondriales." Paris 5, 1998. http://www.theses.fr/1998PA05P151.
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