Maintainence of appropriate redox homeostasis is crucial for processes such as protein folding in the endoplasmic reticulum (ER) and to minimise genesis of oxidative stress. Previous studies have indicated a possible link between ER stress and production of reactive oxygen species (ROS) although the cellular mechanisms involved were not fully elucidated. To investigate the cellular mechanisms involved in tolerance to oxidative stress and ER stress, genome-wide screens were performed to identify mutants sensitive to chronic ER stress induced by dithiothreitol and tunicamycin. These screens identified the Cu,Zn superoxide dismutase (SOD1) and genes involved in NADPH generation (RPE1, TKL1) as important for chronic ER stress tolerance. Superoxide anion has been identified as one of the ROS generated during ER stress. The ER oxidoreductase Ero1p, previously implicated in ROS production in vitro, did not appear to be a source of superoxide when the protein was over-expressed. It was also found that cellular NADP(H) levels affected induction of the unfolded protein response (UPR), since cells lacking TKL1 or RPE1 exhibited decreased UPR induction. These data indicate an important role for superoxide dismutase and cellular NADP(H) in survival of cells during ER stress. Subsequent analysis determined that NADPH generation was also required for adaptation to H2O2. Mutants affected in NADPH production were chronically sensitive to H2O2 but resistant to an acute dose. These mutants over-accumulated reduced glutathione (GSH) but maintained normal cellular redox homeostasis. This over- production of GSH was not regulated at the transcriptional level of GSH1 encoding ??- glutamyl cysteine synthetase. These data raise the important question as to how cells maintain cellular glutathione redox balance. To better understand how cells respond to perturbations in glutathione redox homeostasis, cells deleted for GLR1, encoding GSSG reductase, were exposed to extracellular oxidised glutathione (GSSG) and intracellular GSH and GSSG were monitored over time. Intriguingly cells lacking GLR1 showed increased levels of GSH accumulation upon GSSG treatment in a manner independent of GSH synthesis. It was subsequently found that the cytosolic thioredoxin-thioredoxin reductase system contributes to the reduction of GSSG in vivo.

Thesis (M.S.)--University of Missouri-Columbia, 2007. / "August 2007" The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Includes bibliographical references.

Diss. (sammanfattning) Stockholm : Karol. inst., 2003. / Härtill 6 uppsatser.

Thesis (Ph. D.)--West Virginia University, 2006. / Title from document title page. Document formatted into pages; contains xiv, 197 p. : ill. Vita. Includes abstract. Includes bibliographical references.

Τα μυελοδυσπλαστικά σύνδρομα (ΜΔΣ) χαρακτηρίζονται από μη αποδοτική αιμοποίηση, αναστολή ωρίμανσης των προγονικών κυττάρων του μυελού και αυξημένη ενδομυελική απόπτωση. Η συσχέτιση του ΜΔΣ με την παρουσία αυξημένου οξειδωτικού στρες και οξειδωτικά τροποποιημένων πρωτεϊνών στα προγονικά αιμοποιητικά κύτταρα του μυελού έχει προηγουμένως αναφερθεί. Πρόσφατα βιβλιογραφικά δεδομένα δηλώνουν τη δυνατότητα διάκρισης δύο υποπληθυσμών της μυελικής σειράς βάσει σκεδαστικών χαρακτηριστικών και της έκφρασης του CD45, CD45dim (Neutrophil granulocytic subpopulation-1, NGS1) και CD45high (Neutrophil granulocytic subpopulation-2, NGS2). Ο υποπληθυσμός CD45dim φέρει άωρα κύτταρα, που στην πλειοψηφία τους δεν ωριμάζουν έως τελικού σταδίου[1]. Ο πλήρης χαρακτηρισμός των πληθυσμών αυτών, καθώς επίσης, και η συμμετοχή τους στη μη αποδοτική αιμοποίηση των ΜΔΣ και στην εξέλιξη της νόσου είναι στοιχεία άγνωστα. Σκοπός της παρούσης εργασίας ήταν η διερεύνηση δεικτών απόπτωσης και οξειδωτικού φορτίου (ελεύθερες ρίζες οξυγόνου-ROS) στους υποπληθυσμούς της μυελικής σειράς CD45dim και CD45high. Μελετήθηκαν 17 δείγματα μυελού ασθενών με ΜΔΣ μετά από ανάλυση συνδυασμού 5 χρωμάτων με κυτταρομετρία ροής, για τους δείκτες CD11b/CD16, annexin-V/7-AAD και 2,7-dichlorodihydrofluo-rescein-diacetate(DCF). Η στατιστική ανάλυση των αποτελεσμάτων πραγματοποιήθηκε με τη χρήση του κατάλληλου προγράμματος με μη παραμετρικά κριτήρια (Wilcoxon & Mann-Whitney). Το ποσοστό των αποπτωτικών 7-AAD/annexin-V+ κυττάρων ήταν σημαντικά αυξημένο στα CD45high/ CD11b+/CD16+ της μυελικής σειράς συγκριτικά με τα CD45dim/CD11b+/CD16- κύτταρα. Τα CD45dim και CD45high κύτταρα μυελού με τη χρήση του ειδικού ανιχνευτή των επιπέδων των ελεύθερων ριζών οξυγόνου DCF αναλύθηκαν σε ROSLow και ROSHigh πληθυσμούς. Η ανάλυση με τη χρήση των παραπάνω κριτηρίων έδειξε σημαντική αύξηση του ποσοστού των ROSHigh κυττάρων στα CD45high κύτταρα, συμπεραίνοντας έτσι ότι ο υποπληθυσμός CD45dim έχει χαμηλότερα επίπεδα ενδοκυττάριων ROS εν συγκρίσει με τον CD45high υποπληθυσμό. Ο CD45high υποπληθυσμός της μυελικής σειράς χαρακτηρίζεται από μεγαλύτερα ποσοστά έκφρασης αποπτωτικών δεικτών καθώς επίσης και από τη παρουσία αυξημένου οξειδωτικού φορτίου συγκριτικά με τα CD45dim κύτταρα. Η περεταίρω διερεύνηση του ρόλου των πληθυσμών αυτών στις διαδικασίες ανάπτυξης του ΜΔΣ και στην εξέλιξη της νόσου είναι υπό εξέλιξη. / --

The growth parameters, biochemical, and blood oxidative stress were evaluated in juvenile jundiás fed different levels of vitamin E (0, 200, 300 and 400 mg kg-1 in diet) after 60 days. At the end of the experiment, we observed improvements in growth variables: total length, standard, specific growth rate and condition factor, with the addition of vitamin E in the diet. The erythrocyte count was higher in diets containing vitamin E. The level of 400 mg kg-1 of vitamin E, decreased plasma triglyceride content and increased resistance of erythrocytes. Doses of 300 and 400 mg kg-1, reduced oxidative stress as oxidative biomarkers evaluated in the brain, liver, gills and muscle substances which thiobarbituric acid reactive substances (TBARS), lipid hydroperoxides (LOOH), superoxide dismutase (SOD), catalase (CAT), glutathione-S- transferase (GST) and the content of non-protein thiol groups (NPSH). Doses of vitamin E in the diet of juvenile catfishes above 300 mg kg-1 promotes improvements in growth parameters , and blood antioxidant system . / Os parâmetros de crescimento, bioquímicos, sanguíneos e de estresse oxidativo foram avaliados em juvenis de jundiás alimentados com diferentes níveis de vitamina E (0, 200, 300 e 400 mg kg-1 na dieta) após 60 dias. Ao final do experimento, observaram-se melhoras nas variáveis de crescimento: comprimento total, padrão, taxa de crescimento específico e fator de condição, com a adição de vitamina E na ração. A contagem de eritrócitos foi maior nas dietas contendo vitamina E. O nível 400 mg kg-1 de vitamina E, diminuiu o teor de triglicerídeos plasmáticos e aumentou a resistência dos eritrócitos. As doses de 300 e 400 mg kg-1, reduziram o estresse oxidativo conforme os biomarcadores oxidativos, avaliados no encéfalo, fígado, brânquias e músculo: substâncias que reagem ao ácido tiobarbitúrico (TBARS), hidroperóxidos lipídicos (LOOH), superóxido dismutase (SOD), catalase (CAT), glutationa-S-transferase (GST) e o conteúdo dos grupos tióis não proteicos (NPSH). Doses de vitamina E na dieta de juvenis de jundiás acima de 300 mg kg-1 promovem melhoras nos parâmetros de crescimento, sanguíneos e do sistema antioxidante.

La cachexie est un syndrome complexe caractérisé par une balance énergétique négative. Le rôle joué par le métabolisme énergétique mitochondrial dans ce syndrome est peu connu. Nos précédents travaux montraient une diminution de la synthèse de l’ATP dans les mitochondries hépatiques en stade de cachexie cancéreuse sévère. Dans ce travail, nous démontrons, in vitro, que l’augmentation de la production d’espèce réactive de l’oxygène et du contenu en cardiolipine dans des mitochondries hépatiques saines, mime partiellement les mécanismes observés lors d’un stade cachexie sévère. Nous observons cependant que l’altération du métabolisme mitochondrial hépatique apparait à un stade tardif du développement de la cachexie. En stade sévère les mitochondries musculaires ne développent pas d’altération de leur efficacité de synthèse d’ATP mais une diminution des leurs capacités oxydatives. / Cancer cachexia is a composite syndrome, characterized by a negative energetic balance. The role played by mitochondrial energetic metabolism in this syndrome is poor known. Our past work showed a decrease of ATP synthesis efficiency in hepatic mitochondria in severe state of cancer cachexia. In this work, we demonstrate, in vitro, that increase of reactive oxygen species and cardiolipine content, in healthy mitochondria, can partly mimic the mechanisms observed in severe state of cancer cachexia. We observe that alteration of hepatic mitochondrial metabolism appear last during the development of cancer cachexia. In sever state of cancer cachexia, skeletal muscle mitochondria don’t develop this alteration but demonstrated a decrease of oxidative capacities.

Author did not provide abstract.

APOBEC3A (Apolipoprotein B mRNA-editing enzyme catalytic polypeptide-like editing complex 3 A) appartient à la famille des cytidines désaminases, qui clivent les cytidines en uraciles. APOBEC3G (le modèle de la famille) est un facteur de restriction du VIH : son incorporation dans la particule virale lui permet de désaminer le génome viral néoformé, entrainant hypermutations et dégradation de l’ADN viral. A3A, au contraire, n’est pas incorporée dans la particule virale : la protéine, exprimée spécifiquement dans les cellules myéloïdes de façon inoffensive pour la cellule, agit de la même façon qu’A3G en s’attaquant au virus dès son entrée dans la cellule.Physiologiquement, dans les cellules non-myéloïdes, les APOBEC3 désaminent l’ADN cellulaire simple brin, dont les uraciles sont retirés par UNG2. Les sites abasiques sont clivés par la machinerie de réparation de l’ADN, conduisant parfois à des cassures double-brin et à la mort de la cellule.L’objectif de la thèse était de comprendre cette différence de comportement selon le type cellulaire. Pour cela, des lignées cellulaires inductibles pour A3A ont été créées en cellules HeLa et U937 (monocytaire). Les données obtenues indiquent qu’A3A, partiellement nucléaire, édite l’ADN des cellules en division, conduisant à des dommages à l’ADN, à la production d’espèces réactives de l’oxygène (ROS) et à la mort des cellules. Les cellules différenciées ne présentent pas ce type de dommages, et cela s’explique par une localisation différente de la protéine. Ces résultats permettent de faire pour la première fois le lien entre dommages à l’ADN induits par un membre de la famille des A3 et production de ROS, et donc à l’induction d’une activation immunitaire. Cette activation pourrait avoir des implications dans l’infection ainsi que dans les processus tumorigéniques. / APOBEC3A (Apolipoprotein B mRNA-editing enzyme catalytic polypeptide-like editing complex 3 A) belongs to a family of cytidine deaminases that can edit cytidines to uraciles. APOBEC3G (model protein for the family) is a restriction factor for HIV: since it’s incorporated in the viral particle, it can deaminate the newly formed viral genome leading to hypermutation and viral DNA degradation.A3A is not incorporated in the viral particle: this protein is specifically expressed in myeloid cells where it is harmless for the cell and edits the DNA of the incoming viral particle in the same way than A3G.Physiologically, in non-myeloid cells, APOBEC3s deaminate single strand cellular DNA and the resulting uraciles are cut out by UNG2. These abasic sites are cleaved by the DNA repair machinery and can generate double strand breaks that will result in cell death.The objective of the thesis was to understand this difference of behaviour between different cell types. For that purpose, A3A-inducible cell lines were created in HeLa and U937 (monocytic) cells. The results obtained indicate that partially nuclear A3A edits the genomic DNA of cycling cells, leading to DNA damage, to the production of reactive oxygen species (ROS) and to cell death. Differentiated cells do not present this type of damage and that phenotype can be explained by a different localization of the protein.These results link for the first time DNA damage induced by a member of the A3 proteins family to ROS production and to induction of an immune activation. This activation could have implications in infection as well as in tumorigenic processes.

Made available in DSpace on 2015-07-22T20:50:06Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-06-25. Added 1 bitstream(s) on 2015-08-11T03:25:52Z : No. of bitstreams: 1 Publico-10947.pdf: 1984469 bytes, checksum: 2cce63c3d607e63adb499e8742f10eed (MD5) / O envelhecimento é um processo multi-fatorial associado a déficits funcionais, sendo que o cérebro é um dos órgãos com maior susceptibilidade a doenças crônico-degenerativas. Dentre essas, as doenças de Alzheimer e de Parkinson apresentam maior prevalência na população global e levam à incapacitação severa do indivíduo. Assim, o entendimento dos mecanismos dessas doenças que estão relacionados com o envelhecimento é importante para a busca de alternativas de tratamento. Há evidências de que, em doenças neurodegenerativas, ocorrem alterações na homeostase do cálcio (Ca2+), o que pode contribuir para a morte celular por apoptose. No presente trabalho, buscamos investigar fenômenos envolvidos com a tríade Ca2+ -mitocondria- EROs (espécies reativas do oxigênio) (TOESCU, 2005) e a apoptose em corpo estriado de ratos no envelhecimento. Foram avaliadas a sinalização intracelular dinâmica (em tempo real) e estática (biologia molecular), a morfologia celular e ultraestrutural, a morfometria e bioenergética. Utilizando fatias cerebrais de ratos, observamos que os anmais senescentes apresentaram um aumento de Ca2+ citosólico maior que os animais jovens, após a estimulação glutamatérgica. Em seguida, utilizamos antagonistas parciais das duas classes de receptores, os metabotrópicos do grupo I e os ionotrópicos (NMDAR), para estudar os componentes desse aumento de Ca2+. Avaliamos também o aumento de Ca2+ citosólico mediado por agentes que mobilizam esse íon do retículo endoplasmático e da mitocôndria, mostrando que esses estoques de Ca2+ podem estar aumentados no envelhecimento. As medidas do ∆ψm basal mostraram que hei urna diminuição deste parâmetro no envelhecimento, sendo estas alterações condizentes com a inibição mais acentuada do complexo I da cadeia transportadora de elétrons e do aumento na produção de EROs. As alterações funcionais não implicaram em mudanças ultraestruturais da mitocôndria. Foram investigados a expressão gênica e o conteúdo proteíco de Bax e Bcl-2, mostrando um aumento da expressão de bax e uma redução de proteínas Bcl-2, o que pode ter uma relação com o aumento de apoptose encontrado no estriado dos animais senescentes. Desse modo, os resultados indicam que, no envelhecimento, existem alterações no controle intracelular de sinalização de Ca2+ e na bioenergética, que podem contribuir para o aumento de apoptose. / TEDE / BV UNIFESP: Teses e dissertações