Teses / dissertações sobre o tema "Coenzyme Q"

Title from PDF of title page (University of Missouri--Columbia, viewed on Mar. 15, 2010). The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Dissertation advisors: Dr. Ingolf U. Grün, Dr. Mengshi Lin. Vita. Includes bibliographical references.

Les changements de mode de vie et d'alimentation ont entraîné un développement considérable de l'obésité et des complications métaboliques tels que diabète et/ou athérosclérose. Ces désordres touchant les systèmes endocrinien, immunitaire s'accompagnent de phénomènes inflammatoires et sont associés à une obésité aux dépends du tissu adipeux viscéral. En effet, au-delà de son rôle connu de stockage énergétique sous forme de triglycérides, le tissu adipeux, infiltré de cellules de type macrophagique, est apparu comme un tissu endocrine capable de sécréter hormones et cytokines pro inflammatoires. Le rôle de la mitochondrie et plus généralement le métabolisme d'oxydo-réduction dans le tissu adipeux blanc ont été longtemps négligé mais apparaissent de plus en plus prépondérants. Le but de notre travail a été tout d'abord de développer une technique permettant le dosage de l'état redox du coenzyme Q, seul antioxydant lipophile synthétisé chez l'Homme et présent de manière obligatoire dans la chaîne respiratoire. La technique chromatographique couplée à une détection électrochimique a été validée biologiquement grâce à une approche pharmacologique permettant de moduler le flux électronique de la chaîne respiratoire mitochondriale sur des cellules en culture en augmentant (roténone, carbonyl cyanide chlorophenylhydrazone) ou en diminuant (antimycine) l'oxydation du coenzyme Q. Les modifications du statut tissulaire en coenzyme Q dans des modèles animaux, montre qu'il est un élément régulateur clef de la biologie adipocytaire, nécessaire au métabolisme oxydatif des lipides et à la dépense énergétique. .
The recent evolution of way of life and modifications of food intake involved a considerable development of obesity and associated metabolic complications, which results in co-morbid diseases such as diabetes and/or atherosclerosis. These disorders are generally associated a visceral obesity and related to the endocrine and immune systems but also to inflammatory phenomena. Indeed, beyond its well-known role as energy storage in the form of triglycerides, adipose tissues have endocrine function by secreting hormones and pro-inflammatory cytokines and contained macrophagic cells. The role of mitochondria and the redox metabolism in white adipose tissues was neglected a long time but are now emerging as crucial. To evaluate this, we first set up and validate a technique to measure coenzyme Q, the alone lipophilic antioxidant synthesized by human and an obligatory component of the respiratory chain. To achieve this goal, we used a high performance liquid chromatography-electrochemical technique and we controlled changes in redox state using various inhibitors of mitochondrial respiratory chain

Le coenzyme Q est une molécule lipophile rédox rencontrée chez les eucaryotes et chez la plupart des procaryotes. La structure de Q correspond à une benzoquinone substituée par une chaîne polyisoprényle dont la longueur varie selon les organismes. Q joue le rôle de transporteur d'électrons dans les chaînes respiratoires d'où provient la plupart de l'énergie de la cellule. La biosynthèse de Q chez la bactérie Escherichia coli comporte huit étapes et implique au moins neuf protéines (UbiA-UbiH et UbiX). Trois réactions d'hydroxylation sont nécessaires pour la biosynthèse de Q8 en conditions aérobies. Alors que les protéines UbiH et UbiF présentent des homologies de séquence avec des monooxygénases à flavine connues pour catalyser des réactions d'hydroxylation, UbiB qui a été proposée comme étant la troisième hydroxylase, présente uniquement une homologie de séquence avec des kinases. Nous rapportons dans ce travail que la protéine VisC, renommée UbiI, catalyse la réaction d'hydroxylation auparavant attribuée à UbiB. Nous avons également identifié deux nouvelles protéines (YigP et YqiC, renommées respectivement UbiJ et UbiK) importantes pour le métabolisme de Q chez Escherichia coli puisque leur mutation diminue fortement le contenu en Q des souches mutantes. Ces protéines interagissent avec la plupart des protéines connues pour participer à la biosynthèse de Q ce qui implique l'existence d'un complexe de biosynthèse de Q. En utilisant des approches biochimiques et protéomiques, nous avons pu mettre en évidence un complexe impliquant plusieurs protéines Ubi et notamment UbiJ et UbiK. Ces deux protéines semblent avoir un rôle dans l'assemblage et/ou la stabilisation de ce complexe multiprotéique. Enfin, nous nous sommes intéressés à la biosynthèse de Q dans des conditions de cultures anaérobies. Nos résultats montrent l'existence « d'hydroxylases anaérobies », inconnues à ce jour, qui remplaçent les hydroxylases aérobies UbiH, UbiI et UbiF. Grâce à une approche phylogénétique, nous identifions un gène important pour la biosynthèse de Q uniquement en conditions anaérobies suggérant une réorganisation de la biosynthèse de Q entre ces deux environnements fréquemment rencontrés par E. coli. L'ensemble de nos résultats a permis d'améliorer notre connaissance de la voie de biosynthèse procaryote de Q grâce à la découverte de nouveaux gènes impliqués dans ce processus et grâce à l'identification de la fonction moléculaire de certaines protéines
Ubiquinone (Q) is a lipophilic compound that plays an important role in electron and proton transport in the respiratory chains of Escherichia coli. Besides this important role in energy production, Q also functions as a membrane soluble antioxidant. The biosynthesis of Q8 requires eight reactions and involves at least nine proteins (UbiA-UbiH and UbiX) in Escherichia coli. Three of these reactions are hydroxylations resulting in the introduction of a hydroxyl group on carbon atoms at position 1, 5 and 6 of the aromatic ring. The C1 and C6 hydroxylation are well characterized whereas the C5 hydroxylation has been proposed to involve UbiB, a protein kinase without any sequence homology with monooxygenase. In this work, by genetic and biochemical methods we provide evidence that VisC which we renamed UbiI, displays sequence homology with monooxygenases and catalyzes the C5 hydroxylation, not UbiB. We have identified two new genes, yqiC and yigP (renammed UbiJ and UbiK) which are required only for Q8 biosynthesis in aerobic conditions. The exact role of the corresponding proteins, renamed UbiJ and UbiK, remains unknown. These proteins are able to interact with other Ubi proteins to be able to produce Q supporting the protein complex hypothesis. Our progress on the characterization of an Ubi-complex regrouping several Ubi proteins suggest that UbiJ and UbiK may fulfill functions related to the Ubi-complex stability. Mutants affected in hydroxylation steps are deficient for Q8 in aerobic conditions but recover a wild type Q8 content when grown in anaerobic conditions. This intriguing observation supports the existence of an alternative hydroxylation system independent from dioxygen which has not been characterized so far. By phylogenetic studies, we have identified a new gene in which the deletion affect the biosynthesis of Q only in anaerobic conditions suggesting a reorganization of Q biosynthesis in these two conditions. Our results has improved our knowledge of the prokaryotic Q biosynthetic pathway through the discovery of new genes involved in this process and through the identification of the molecular function of some proteins

A hiperglicemia crônica favorece a ocorrência da nefropatia induzida por contraste iodado (NIC). Diabetes Mellitus (DM) e NIC compartilham mecanismos de lesão oxidativa e indução de enzimas de proteção e adaptação celular como a coenzima Q-10 (COQ-10). O objetivo deste estudo foi avaliar o papel da COQ-10 na função e hemodinâmica renal, perfil oxidativo e histologia renal em ratos diabéticos submetidos ao modelo de NIC. Métodos: Ratos Wistar, machos, 250 a 290 g, foram randomizados nos grupos: Citrato: animais que receberam tampão citrato 0,01M, (veículo da estreptozotocina), 0,4 ml intravenoso (i.v), 1 vez; Tween 80: animais que receberam Tween 80, 1%, (veículo da COQ-10), 0,5 ml, intraperitoneal (i.p.), 1 vez; DM: animais que receberam estreptozotocina (65 mg/kg), i.v., 1 vez, no 1º dia do protocolo; DM+CI: animais DM que no 26º dia de protocolo receberam contraste iodado (CI, 6 ml/kg), i.p., 1 vez; DM+CI+COQ-10: animais DM com pré-condicionamento com COQ-10 (10 mg/kg), 1 vez por 6 dias a partir do 22º dia de protocolo, e o tratamento com CI. O protocolo de todos os grupos teve duração de 4 semanas. Foram avaliados parâmetros fisiológicos (ingestão de ração e água, peso, glicemia, razão peso do rim e peso do animal), a função renal (clearance de inulina), a hemodinâmica renal (fluxo sanguíneo renal e resistência vascular renal), o perfil oxidativo (peróxidos, óxido nítrico e substâncias reativas ao ácido tiobarbitúrico na urina, tióis no tecido renal) e análise histológica renal. Resultados: Animais DM apresentaram hiperglicemia, polidipsia, poliúria, polifagia, perda de peso e aumento da relação peso rim/animal, com redução da função renal, além de redução do fluxo sanguíneo renal, elevação da resistência vascular renal, com aumento na excreção de metabólitos oxidativos e consumo de reserva antioxidante endógena. O grupo DM+CI demonstrou redução adicional na função, alterações na hemodinâmica renal e aumento nos parâmetros de estresse oxidativo. A administração de COQ-10 atenuou a redução da função renal, preveniu alterações hemodinâmicas renais e reduziu o estresse oxidativo no grupo DM+CI. As alterações histológicas no DM e DM+CI foram discretas e o tratamento com COQ-10 previniu a progressão de danos histológicos mais extensos nos animais que receberam CI. Conclusão: O tratamento com COQ-10 demonstrou efeito antioxidante na NIC em ratos diabéticos com melhora significativa da função e hemodinâmica renal.
Chronic hyperglycemia favors the occurrence of nephropathy induced by iodinated contrast (CIN). Diabetes Mellitus (DM) and CIN share oxidative damage mechanisms and induction of protective and cellular adaptation enzymes as coenzyme Q-10 (CoQ-10). The aim of this study was to investigate the role of COQ-10 in renal function and hemodynamics, oxidative profile and renal histology in diabetic rats submitted to the NIC model. Methods: Wistar rats, male, weighing 250-290 g, were randomized into two groups: Citrate: animals that received citrate buffer 0.01M (streptozotocin), 0.4 ml, intravenous (i.v.), once; Tween 80: animals that received Tween 80, 1% (CoQ-10 vehicle), 0.5 ml, intraperitoneal (i.p.), once; DM: animals given streptozotocin (65 mg/kg) i.v., once on the first day of the protocol; CI+DM: DM animals, on the 26º day protocol, tretated with iodinated contrast (CI, 6 ml/kg) i.p., once; DM+CI+COQ-10: DM animals preconditioned with COQ-10 (10 mg/kg), once a day, for 6 days from the 22º day and treated with CI. The protocol for all groups lasted 4 weeks. Physiological parameters evaluated were (food and water intake, corporal weight, blood glucose and right kidney weight), renal function (inulin clearance), renal hemodynamics (renal blood flow and renal vascular resistance), the oxidative profile (peroxides, nitric oxide and reactive substances to thiobarbituric acid in urine, thiols in renal tissue) and renal histological analysis. Results: DM animals showed hyperglycemia, polydipsia, polyuria, polyphagia, weight loss and increased weight kidney / animal relationship with reduced renal function, as well as a reduction on renal blood flow, increased renal vascular resistance and changes in oxidative profile with increased the excretion of metabolites and oxidative consumption of endogenous antioxidant reserve. DM+CI promoted further reduction in renal function, exacerbated hemodynamic changes and increase in oxidative stress parameters. COQ-10 administration preserved renal function, prevented hemodynamic changes and reduced oxidative stress in the DM + CI + COQ-10. Histological changes in DM and DM + CI were discrete and treatment with CoQ-10 prevented the progression of the histologic damage in the animals receiving CI. Conclusion: COQ-10 presented an antioxidant effect on the NIC in diabetic rats, by improving function and renal hemodynamics and reducing oxidative stress.

ARCA2 est une ataxie récessive qui se caractérise par une atrophie du cervelet et un léger déficit en coenzyme Q10. Des mutations dans le gène ADCK3 ont été récemment identifiées comme étant la cause d’ARCA2. ADCK3 code pour une kinase mitochondriale atypique, qui pourrait être impliquée dans la biosynthèse du coenzyme Q10. L’objectif de mon projet de thèse était d’élucider la physiopathologie d’ARCA2 en utilisant le modèle murin knockout pour Adck3. J’ai ainsi pu montrer que les souris Adck3-/- reproduisent de nombreux symptômes associés à ARCA2 et constituent un bon modèle pour étudier ARCA2. Au niveau du cervelet, les cellules de Purkinje sont spécifiquement touchées et présentent des anomalies morphologiques et fonctionnelles. Un léger défaut mitochondrial a été observé dans les muscles squelettiques des souris Adck3-/-. Enfin, une analyse transcriptomique de ces deux tissus a révélé des altérations de nombreuses voies, impliquant ADCK3 dans de nouveaux processus cellulaires
ARCA2 is a form of recessive ataxia characterized by a slow progression of the ataxic phenotype, cerebellar atrophy and mild deficit in Coenzyme Q10. ARCA2 was recently found associated with mutations in the ADCK3 gene that encodes a putativemitochondrial kinase homologous to the yeast Coq8 and the bacterial UbiB proteins, which are required for Coenzyme Q biosynthesis. In order to elucidate the pathophysiology of ARCA2, a constitutive knockout mouse for Adck3 was generated.Adck3-/- mice reproduce many ARCA2 symptoms such as slow progression of the ataxic phenotype and mild Coenzyme Q deficit, suggesting that Adck3-/- mice are a good model to study ARCA2. Strikingly, a morphological and functional impairmentwas found in cerebellar Adck3-/- Purkinje cells, whereas a mild mitochondrial defect was observed in the skeletal muscle of Adck3-/- mice. Interestingly, transcriptomic analyses revealed alteration in a number of molecular pathways implicating ADCK3in novel cellular processes

ARCA2 est une ataxie autosomique récessive rare, caractérisée par une atrophie du cervelet et un léger déficit en Coenzyme Q10 (CoQ). La majorité des patients présentent des signes neurologiques supplémentaires comme l’épilepsie ou l’intolérance à l’exercice. La maladie est due à des mutations dans le gène COQ8A qui semble encoder une protéine kinase-like atypique, impliquée dans la biosynthèse du CoQ. Pour comprendre les mécanismes physiopathologiques, une souris Coq8a knock-out (KO) constitutif a été générée et récapitule les symptômes observés chez les patients. Le but de ce travail de thèse était de mieux comprendre certains aspects, notamment l’intolérance à l’exercice et l’ataxie. Malgré un déficit en CoQ dans les muscles, aucun défaut de respiration mitochondriale n’a été détecté dans un modèle cellulaire de muscle. Néanmoins, dans le cervelet, les niveaux de transcrits de 27 gènes sont dérégulés, précocement dans l’apparition de la pathologie chez les souris KO. Les voies métaboliques vont être explorées, ce qui devrait permettre de relier la fonction de COQ8A au taux de CoQ et aux symptômes observés chez les patients
ARCA2, a rare form of recessive ataxia, is characterized by early onset progressive ataxia, cerebellar atrophy and a mild Coenzyme Q10 deficiency. Most of the patients show additional neurological signs such as epilepsy and exercise intolerance. Mutations in the COQ8A gene lead to ARCA2. COQ8A is suggested as being an unorthodox protein kinase like, with a regulatory role in CoQ biosynthesis, in mammals. To better understand ARCA2, a constitutive Coq8a knock-out (KO) mouse model was generated, which recapitulates most of the patient’s symptoms. Here we report the use of cellular models and the affected tissues to uncover the molecular signature of COQ8A loss and CoQ deficit. Despite CoQ deficit in the muscle, no mitochondrial bioenergetics defect was uncovered. In parallel, we have identified, by RT-qPCR, a key set of genes that are dysregulated in cerebellum, very early on in the pathology. We are currently investigating these pathways to uncover the link with COQ8A function. Altogether, our experiments will shed light on the early molecular events that lead to ARCA2 and may help draw a link between COQ8A function, CoQ pools and the symptoms observed in patients

Le pore de transition de perméabilité mitochondriale (PTPm) joue un rôle majeur dans la mort cellulaire et dans la cardioprotection. Notre hypothèse est que le complexe I de la chaîne respiratoire est impliqué dans la régulation de l'ouverture du PTPm. Sur des mitochondries isolées de cœurs des rongeurs, nous avons pu démontrer que le PTPm est désensibilisé par la cyclosporine A, un inhibiteur de la cyclophiline D (CyP-D), et cet effet est largement amplifié en présence de la roténone, un inhibiteur du complexe I. Ces résultats ont été confirmés chez la souris CyP-D déficiente. L'étude de plusieurs types cellulaires a aussi confirmé l'effet de la roténone dans la régulation du PTPm. Ainsi, nous avons pu montrer que le flux d'électrons travers le complexe I est capable de réagir sur un site de régulation du PTPm cardiaque masqué par la CyP-D. De plus, les analogues de l'ubiquinone, élément de la chaîne respiratoire impliqué dans le transfert d'électrons entre les complexes I, II et III, modulent la susceptibilité du PTPm vis-à-vis du Ca2+. Par ailleurs, dans un modèle de cœur isolé du rat, le postconditionnement par le perindoprilate, un inhibiteur de l'enzyme de conversion, diminue la taille de l'infarctus après l'ischémie-reperfusion d'une façon NO-dépendant. L'ensemble de nos résultats ouvre de nouvelles perspectives thérapeutiques dans la cardioprotection et montre l'importance du complexe I et de la CyP-D comme cibles moléculaires incontournables dans la cardioprotection

The master thesis addresses the issue of cultivation of selected strains of carotenogenic yeasts on waste materials of the food industry using a laboratory bioreactor. Carotenogenic yeasts are able to produce highly valuable metabolites during cultivation, which are located predominantly in the lipid part of the cells. Particularly, they are carotenoids, ergosterol, coenzyme Q and fatty acids. The thesis is divided into two main parts, the theoretical part and the practical part. The theoretical part describes individual yeast strains, types of waste materials, produced metabolites and methods of their analysis. The experimental part deals with the processing of waste materials of the food industry, specifically animal fat, whey and spent coffee grounds into the form of substrates usable as nutrition sources for yeast cultivation. Furthermore, cultivations focused on the recovery of the monitored metabolites and their analysis by using HPLC/PDA and GC/FID assemblies were studied as well. The yeast strains Rhodotorula mucilaginosa (CCY 19-4-6), Rhodotorula kratochvilae (CCY 20-2-26), Rhodosporidium toruloides (CCY 062-002-001), Sporidiobolus pararoseus (CCY 19-9-6) a Cystofilobasidium macerans (CCY 10-1-2) were used in this work. As one of the best producing strains Sporidiobolus pararoseus (CCY 19-9-6) was found, which achieved very high productions of carotenoids, coenzyme Q and ergosterol.

A coenzima Q transporta elétrons das NADH e succinato desidrogenase para o complexo bc1 da cadeia respiratória mitocondrial. Há dez produtos gênicos conhecidos em seu metabolismo; este trabalho foca o último a ser descrito: COQ10. Considerando a presença de coenzima Q no interior de células contendo este gene inativo, verificamos a atividade respiratória da coenzima Q em mutantes coq10. Através de inibidores do ciclo da coenzima Q no interior do complexo III da cadeia respiratória mitocondrial (antimicina A e mixotiazol) na linhagem coq10, notou-se sua resposta a antimicina A, mas não a mixotiazol, sugerindo a existência de semiquinonas, que também foram confirmadas em testes de ressonância paramagnética eletrônica. O possível transporte e distribuição da coenzima Q por Coq10p foi estudado através de mutações sítio-dirigidas em posições críticas de um túnel de ligação existente em sua estrutura modelar, bem como por análise de super-expressão da proteína. Este trabalho confirma o papel central de Coq10p no metabolismo respiratório.
Coenzyme Q transports electrons from NADH and succinate dehydrogenase to the bc1 complex of the mitochondrial respiratory chain. Ten gene products are involved in coenzyme Q metabolism. This work focuses on the last gene to be described: COQ10. Considering the presence of coenzyme Q in the interior of cells containing this gene inactive, we analyzed the respiratory activity of coenzyme Q in coq10 mutants. By using Q cycle inhibitors, in the interior of the complex III of mitochondrial respiratory chain (antimycin A and mixotiazol), in coq10 lineage, it was noted the response to antimycin A, but not mixotiazol, suggesting the existence of semiquinones, which were also confirmed in tests of electron paramagnetic resonance. The possible transmission and distribution of coenzyme Q by Coq10p was studied by site-directed mutagenesis at critical positions of a tunnel present in the molecular model structure, as well as analysis of over-expression of the protein. This study confirms the central role of Coq10p in respiratory metabolism.

Cancer is the second leading cause of death in the United States and its onset is highly incident in the lungs, with very low long-term survival rates. Chemotherapy plays a significant role for lung cancer treatment, and pulmonary delivery may be a potential route for anticancer drug delivery to treat lung tumors. Coenzyme Q₁₀ (CoQ₁₀) is a poorly-water soluble compound that is being investigated for the treatment of carcinomas. In this work, we hypothesize that formulations of CoQ10 may be developed for pulmonary delivery with a satisfactory pharmacokinetic profile that will have the potential to improve a pharmacodynamic response when treating lung malignancies. The formulation design was to use a vibrating-mesh nebulizer to aerosolize aqueous dispersions of CoQ₁₀ stabilized by phospholipids physiologically found in the lungs. In the first study, a method was developed to measure the surface tension of liquids, a physicochemical property that has been shown to influence the aerosol output characteristics from vibrating-mesh nebulizers. Subsequently, this method was used, together with analysis of particle size distribution, zeta potential, and rheology, to further evaluate the factors influencing the capability of this nebulizer system to continuously and steadily aerosolize formulations of CoQ₁₀ prepared with high pressure homogenization. The aerosolization profile (nebulization performance and in vitro drug deposition of nebulized droplets) of formulations prepared with soybean lecithin, dimyristoylphosphatidylcholine (DMPC), dipalmitoylphosphatidylcholine (DPPC) and distearoylphosphatidylcholine (DSPC) were evaluated. The rheological behavior of these dispersions was found to be the factor that may be indicative of the aerosolization output profile. Finally, the pulmonary deposition and systemic distribution of CoQ₁₀ prepared as DMPC, DPPC, and DSPC dispersions were investigated in vivo in mice. It was found that high drug amounts were deposited and retained in the mouse lungs for at least 48 hours post nebulization. Systemic distribution was not observed and deposition in the nasal cavity occurred at a lower scale than in the lungs. This body of work provides evidence that CoQ₁₀ may be successfully formulated as dispersions to be aerosolized using vibrating-mesh nebulizers and achieve high drug deposition in the lungs during inhalation.

The aim of this thesis is to investigate molecular mechanism of reactive oxygen species production by flavin dehydrogenases mitochondrial glycerol-3-phosphate dehydrogenase (mGPDH) and succinate dehydrogenase (SDH). Together, they represent important source of reactive oxygen species in mammalian mitochondria, but the mechanism of electron leak is still poorly understood. Because mechanisms of reactive oxygen species production by other complexes of respiratory chain are better characterized, they can serve as case studies to get insight into mechanisms of reactive oxygen species by flavin dehydrogenases. Relevant knowledge is therefore summarized in the first part of the thesis. To study the production of reactive oxygen species by the isolated flavin dehydrogenases, we used brown adipose tissue mitochondria solubilized by digitonin as a model. Enzyme activity measurements, hydrogen peroxide production studies by Amplex UltraRed fluorescence and luminol luminescence revealed flavin as the most likely source of electron leak in SDH under in vivo conditions, while we propose coenzyme Q binding site as the site of reactive oxygen species production in the case of mGPDH. Distinct mechanism of this production by the two dehydrogenases is also apparent from induction of reactive oxygen species...