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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Rôle de la signalisation purinergique dans la régulation de la migration des kératinocytes

Faure, Emilie 27 March 2012 (has links)
L'épiderme est un tissu stratifié, majoritairement constitué de kératinocytes qui forme la première barrière de l'organisme contre les agressions extérieures. Après blessure cutanée, la migration des kératinocytes est une phase cruciale de la cicatrisation. Le comportement des kératinocytes est placé sous le contrôle des molécules de la matrice extracellulaire ainsi que par les facteurs solubles (facteurs de croissance et cytokines..) sécrétés dans le microenvironnement. Les cellules résidentes ou recrutées sur le site de lésion libèrent également des nucléotides extracellulaires (ATP, UTP) dans l'environnement des kératinocytes. Dans ce travail de thèse, nous avons examiné l'impact des nucléotides extracellulaires et du récepteur purinergique P2Y2 sur la migration des kératinocytes et sur l'activité motogénique de deux facteurs de croissance, l'IGF-I et de l'EGF. Dans un premier temps, nous avons pu montrer que l'activation de P2Y2 et de la protéine hétérotrimérique Gαq inhibe l'activité de l'isoforme p110α de la PI3K sur des cellules stimulées par l'IGF. Cette inhibition de la voie PI3K/Akt aboutit à une perturbation de la mobilisation de la cortactine et de la formation des lamellipodes ainsi qu'une diminution de la vitesse de migration des kératinocytes. Dans un second temps, nous avons mis en évidence que l'activation de P2Y2 inhibe l'activation de la voie ERK1/2 par l'EGF en inhibant la phosphorylation des protéines MEK1/2, ERK1/2 et p90RSK. Nous avons établi que la conséquence de cette inhibition est la stabilisation des hémidesmosomes / The epidermis is a stratified tissue, mainly composed of keratinocytes, that forms the first barrier of the organism. When skin injury occurs, the epidermis structure is altered and many signalling pathways are activated in order to re-establish its homeostasis. Among these signalling pathways, the PI3K and MAPK ERK1/2 pathways play key roles by controlling keratinocyte migration and proliferation. The aim of this thesis was to analyse the regulation of these two signalling pathways by extracellular nucleotides, acting through purinergic receptors P2Y2 and the heterotrimeric Gαq protein and to evaluate the impact of this receptor on keratinocyte migration. Firstly, we showed that P2Y2 receptor activation inhibits PI3K p110α isoform and consequently alters keratinocyte cell shape and migration. Additionally, we showed that purinergic signalling activation inhibits EGF-induced ERK1/2 pathway activation by inhibiting the phosphorylation of MEK1/2, ERK1/2 and p90RSK proteins. As a consequence, P2Y2 stabilizes α6β4 integrin localisation into hemidesmosome-like structures and inhibits keratinocyte migration. The involvement of purinergic signalling pathway in regulation of different signalling events suggests that it may play a central role in regulation of cellular events that occurred during skin wound healing process. Moreover, our present data in association with those of the literature show that extracellular nucleotides can act as a double-edged sword in the regulation of cell migration: either activate or block cell migration in a striking cell-specific manner.
12

Analyses biochimiques et fonctionnelles de protéines cibles de POFUT1 / Biochemical and functional analyses of POFUT1 target proteins

Pennarubia, Florian 14 December 2018 (has links)
La O-fucosylation, catalysée par Pofut1, est une glycosylation rare qui consiste en l’ajout d’un fucose O-lié sur la sérine ou la thréonine d’une séquence consensus (C2X4(S/T)C3), portée par un domaine EGF-like (ELD) d’une glycoprotéine membranaire ou sécrétée. Notre analyse de la lignée murine Pofut1cax/cax, hypomorphe pour le gène Pofut1, a révélé une hypertrophie musculaire post-natale associée à une diminution du pool de cellules satellites. Ce phénotype est en partie associé à un défaut d’interaction entre les récepteurs NOTCH hypo-O-fucosylés des myoblastes dérivés de cellulessatellites (MDCS) et leurs ligands DSL, ce qui aboutit à une plus faible activation de la signalisation Notch. D’autres protéines potentiellement impliquées dans la myogenèse peuvent également être la cible de POFUT1. C’est notamment le cas de la protéine Wnt inhibitory factor 1 (WIF1), qui dispose de cinq ELDs, dont deux sont potentiellement aptes à recevoir un O-fucose (ELDs III et V). Par une approche phylogénétique, nous avons montré la conservation de ces deux sites de O-fucosylation et de deux sites de N-glycosylation chez la plupart des bilatériens. Nos expériences démontrent l’occupationde tous ces sites, excepté le site de O-fucosylation de l’ELD V, chez la protéine WIF1 murine. La capacité de l’ELD III, produit de manière isolée, à recevoir un fucose O-lié a été démontrée après O-fucosylation in vitro, par l’association de cycloaddition azide-alcyne assistée au cuivre (CuAAC) et de spectrométrie de masse en mode MRM. Cette nouvelle approche expérimentale a par la suite été standardisée et sa sensibilité évaluée en comparant deux autres ELDs (ELDs 12 et 26 de NOTCH1) connus pour être O-fucosylés mais présentant des affinités différentes pour POFUT1. De façonsurprenante, l’ELD V de WIF1 ne peut être O-fucosylé, probablement en raison d’un clash stérique entre cet ELD et POFUT1, prévenant ainsi leur interaction. L’analyse de la protéine WIF1 entière a confirmé les résultats obtenus sur les ELDs isolés et démontre l’occupation des deux sites de N-glycosylation. Enfin, nos résultats montrent également l’importance de ces deux N-glycanes, mais également celle du O-fucose de l’ELD III, pour une sécrétion optimale de la protéine WIF1 murine. / The, Pofut1-catalyzed O-fucosylation, is a rare glycosylation which consists of the addition of an O-linked fucose to the serine or threonine of a consensus sequence (C2X4(S/T)C3), carried by an EGF-like domain (ELD) of a membrane or secreted glycoprotein. Our analysis of the murine line Pofut1cax/cax, hypomorphic for the Pofut1 gene, revealed post-natal muscle hypertrophy associated with a decrease in the satellite cell pool. This phenotype was partly associated with a lack of interaction between hypo-O-fucosylated NOTCH receptors of satellite cell-derived myoblasts (SCDM) and their DSL ligands, which resulted in a lower activation of Notch signaling. Other proteins potentially involved in myogenesis may also be the target of POFUT1. This is indeed the case for the protein Wnt inhibitory factor 1 (WIF1), which has five ELDs, whose only two are potentially able to receive an O-fucose (ELDs III and V). Using a phylogenetic approach, we showed in most bilaterians that these two O-fucosylation sites and two N-glycosylation sites were conserved. Our experiments showed theoccupation of all these sites, except for the O-fucosylation site of murine WIF1 protein ELD V. The ability of the ELD III, produced as an isolated protein, to receive O-linked fucose was demonstrated after an in vitro O-fucosylation by combination of copper-catalysed azide-alkyne cycloaddition (CuAAC) and MRM-mass spectrometry. This new experimental approach was then standardized and its sensitivity was evaluated by comparing two other ELDs (NOTCH1 ELDs 12 and 26) known to beO-fucosylated but with different affinities for POFUT1. Surprisingly, WIF1's ELD V could not be O-fucosylated, probably due to a steric clash between this ELD and POFUT1, thus preventing their interaction. The analysis of the full-length WIF1 protein confirmed our results obtained with isolated ELDs and demonstrated the occupation of the two N-glycosylation sites. Finally, our results also showed the importance of these two N-glycans, but also the importance of ELD III’s O-fucose, foroptimal secretion of the murine WIF1 protein.
13

Ação da Proteína Kinase C na maturação de oócitos bovinos / Role of Protein Kinase C on bovine oocyte maturation

Lopes, Everton 28 June 2012 (has links)
A qualidade do oócito é um fator limitante na fertilidade das fêmeas e reflete seu intrínseco potencial ao desenvolvimento embrionário subsequente. As alterações moleculares e bioquímicas no processo de maturação dos oócitos são necessárias para permitir a fecundação destes. Sob influência das gonadotrofinas, uma cascata de eventos é desencadeada, alterando a expressão gênica e a estrutura dos folículos. A maturação ocorre pelo intercâmbio entre o oócito e as células do cumulus que irão fornecer fatores para o desenvolvimento do oócito e criar o microambiente necessário para garantir o sucesso na maturação. A ação do FSH sobre a retomada da meiose ocorre, possivelmente, por ativação da proteína quinase C (PKC). A via de sinalização desta proteína parece estar envolvida na ativação da quinase ativada por mitógeno (MAPK) em oócitos e células do cumulus, na maturação induzida por FSH e LH, além de regular a síntese do Fator de Crescimento Epidermal (EGF). Deste modo, o objetivo do presente trabalho foi avaliar a ação da PKC na maturação de oócitos bovinos e se esta ativação envolve o EGF. Para tal foram realizados dois experimentos. Em ambos, a progressão do ciclo celular foi avaliada utilizando a sonda fluorescente Hoechst 33342. A expansão das células do cumulus foi avaliada utilizando-se o software Image Pro Plus 5.1 para análise das imagens dos oócitos geradas em microscópio Olympus IX81. O maior diâmetro de cada complexo cumulus oócito foi adotado como parâmetro de mensuração da expansão. A dosagem de progesterona do meio de cultivo foi realizada pela técnica de RIA. A ativação da PKC e da MAPK foi avaliada pela técnica de Western blot. Os dados foram avaliados pelo software SigmaPlot versão 12.2 e submetidos ao teste de normalidade (Shapiro-Wilk). Quando necessário, os dados foram transformados. Para comparação entre dois tratamentos, utilizou-se o teste t-student. Para mais de dois tratamentos foi realizada análise de variância e teste de comparação de médias (TUKEY), considerando-se 0,05 para rejeitar a hipótese de nulidade. No experimento 1 foi avaliado se a ativação da PKC foi estimulada por gonadotrofinas. Os oócitos foram maturados in vitro tratados com gonadotrofinas, na presença ou ausência do inibidor de PKC. A presença do inibidor de PKC diminuiu as taxas de quebra de vesícula germinativa e a expansão das células do cumulus, sem alterar a esteroidogênese. Estes resultados demonstram que a PKC participa da via de sinalização da retomada da meiose. No experimento 2 foi avaliado se o EGF está envolvido na via regulada pela PKC. Os oócitos foram maturados in vitro, na presença ou ausência de LH e FSH, do inibidor de PKC e do EGF. O EGF foi capaz de reverter os efeitos do inibidor de PKC, aumentando as taxas de quebra de vesícula germinativa e a expansão de células do cumulus. Não foi possível detectar, nas condições deste experimento, a ativação das proteínas PKC e MAPK através do Western Blot. Este trabalho permite concluir que a via de sinalização da maturação de oócitos bovinos envolve a PKC e sugere a participação do EGF nesta via. / Oocyte quality is a limiting factor in female fertility and reflects its potential to the subsequent embryonic development. Molecular and biochemical alterations during the oocyte maturation process are needed to allow fecundation. Under gonadotropin influence, cascade of events occurs changing gene expression and follicle structure. Maturation depends on the interaction between oocyte and cumulus cells interaction, which provides factors for oocyte development and create the ideal microenvironment for the success of the maturation process. The FSH stimulation of meiosis resumption probably occurs through PKC activation. The signaling pathway of PKC might be involved by the mitogen activated protein kinase (MAPK) in oocytes and cumulus cells during FSH-LH induced maturation. Furthermore, MAPK regulates the epidermal growth factor (EGF) synthesis. The aim of the present study was to evaluate PKC function during bovine oocyte maturation and if its activity involves EGF. Two experiments were performed. In both experiments, the cell cycle progression was analyzed by Hoechst 33342 fluorescent dye. The cumulus cells expansion was performed using software Image Pro Plus 5.1 by the analysis of oocyte images taken in Olympus IX81 microscope. The highest diameter of each cumulus oocyte complex was recorded as the expansion value. The RIA and Western Blot techniques were used to measure progesterone concentration in the culture media and the PKC and MAPK activity, respectively. Data was analyzed by SigmaPlot software, version 12.2. The Shapiro-Wilk test was used to assess for normality and, when needed, the data was transformed. Student t tests were carried out to compare two treatments. Differences between more than two means were assessed by analysis of variance followed by Tukey test, considering P-value lower than 0.05 as statistically significant. Experiment 1 studied whether PKC function was stimulated by gonadotropins. FSH and LH were used for oocyte maturation in vitro, with or without PKC inhibitor. The presence of PKC inhibitor decreased germinal vesicle breakdown and the cumulus cells expansion, but did not alter the steroidogenesis. These results show that PKC participates in the signaling pathway of meiosis resumption. The Experiment 2 evaluated whether EGF influences PKC signaling pathway. The oocytes were matured in vitro, in the presence or absence of LH and FSH, PKC inhibitor and EGF. Epidermal Growth Factor was able to reverse PKC inhibitor effects, increasing germinal vesicle breakdown rates and cumulus cells expansion. The Western Blot technique was not able to detect PKC and MAPK activity, considering the conditions of this study. In conclusion, PKC is involved in the signaling pathway of bovine oocytes maturation and its pathway is mediated by EGF.
14

Aparato de importação de proteínas mitocondriais em Aspergillus fumigatus: caracterização fenotípica da deleção da menor subunidade do complexo TIM23 / Proteomic changes of the epithelial-mesenchymal transition (TMS) in cancer of ovary: involvement in cell cycle control and energy metabolism

Silva, Alinne Costa 20 December 2016 (has links)
O câncer de ovário (OvCa) se destaca dentre as neoplasias ginecológicas por ser um dos mais letais e de difícil diagnóstico. O OvCa ocorre devido ao acúmulo de alterações celulares progressivas promovidas por mutações no genoma de uma célula que, consequentemente, alteram as complexas vias de regulação celular que respondem a fatores internos, como reprogramação genética, ou externos, como a resposta a fatores de crescimento, que juntamente com outras alterações moleculares favorecem a progressão e a metástase. Uma importante etapa da cascata metastática é a transição epitélio-mesenquimal (EMT), um processo bem orquestrado que resulta na perda do fenótipo epitelial e aquisição do fenótipo mesenquimal pelas células tumorais, que adquirem um caráter mais invasivo e migratório, além de se tornarem mais resistentes às drogas. A desregulação de fatores de transcrição como ZEB1, TWIST e SNAI1, vias de sinalização, microRNAs e fatores de crescimento incluindo EGF, TGF? e HGF podem desencadear a EMT. Após a eficiente indução da EMT com EGF na linhagem epitelial de adenocarcinoma de ovário humano Caov-3, foi realizada a análise proteômica quantitativa detalhada, baseada na análise de frações subcelulares enriquecidas em proteínas de membrana, citosol e núcleo, obtidas por centrifugação diferencial e subsequente fracionamento de proteínas por SDS-PAGE, a fim de compreender mais profundamente os mecanismos moleculares modulados pela EMT no OvCa. A partir da análise dos dados coletados em um sistema de espectrometria de massas de alta resolução acoplados a cromatografia líquida (LCMS/MS) e com o auxílio da bioinformática foram identificadas redes de interação proteína-proteína diferencialmente expressas, relacionadas principalmente com a regulação do ciclo celular e do metabolismo. A indução da EMT por EGF resultou na ativação de importantes vias de sinalização, tais como PI3K/Akt/mTOR e Ras/MAPK Erk, além da parada do ciclo celular na fase G1 regulada pelo aumento dos níveis de p21Waf1/Cip1, independentemente de p53, e diminuição de proteínas checkpoint. Através da proteômica dirigida, o monitoramento de reações múltiplas (MRM) revelou que, após a indução da EMT por EGF, o metabolismo das células Caov-3 foi alterado de uma maneira bastante peculiar. O estudo proteômico descrito permitiu a correlação entre processo da EMT induzido por EGF com o controle translacional, a regulação do ciclo celular e a alteração do metabolismo energético. / Ovarian cancer (OvCa) stands out among gynecological malignancies for being one of the most lethal and difficult to diagnose. OvCa occurs due to the accumulation of progressive cell changes promoted by mutations in the cell genome which, consequently, alter the complex cellular regulation pathways that respond to internal factors, such as genetic reprogramming, or external, such as response to growth factors, which together with other molecular changes favor the progression and metastasis. An important step of the metastatic cascade is the epithelial-mesenchymal transition (EMT), a well-orchestrated process that results in the loss of epithelial phenotype and acquisition of mesenchymal phenotype by tumor cells that acquire a more invasive and migratory character, and become more resistant to drugs. Deregulation of transcription factors such as ZEB1, TWIST and SNAI1, signaling pathways, microRNAs and growth factors including EGF, TGF? and HGF can trigger EMT. After an efficient EMT induction by EGF in the epithelial cell line of human adenocarcinoma ovarian Caov-3, detailed quantitative proteomic analysis was performed based on analysis of subcellular fractions enriched in proteins from membrane, cytosol and nucleus, obtained by differential centrifugation and subsequent fractionation of proteins by SDS-PAGE, in order to understand deeply the molecular mechanisms modulated by EMT in OvCa. From the analysis of data collected in a highresolution mass spectrometry system coupled to liquid chromatography (LC-MS/MS) and with the aid of bioinformatics were identified protein-protein interaction networks differentially expressed, mainly related to regulation cell cycle and metabolism. EGF induced-EMT resulted in the activation of major signaling pathways such as PI3K/Akt/mTOR and Ras/MAPK Erk, in addition to G1 phase cell cycle arrest regulated by increased levels of p21Waf1/Cip1, regardless of p53, and reduction of checkpoint proteins. Through the targeted proteomics, multiple reaction monitoring (MRM) showed that after EGF induced-EMT, Caov-3 cells metabolism was changed in a very particular way. The proteomic study described allowed the correlation between EMT process induced by EGF with translational control, regulation of cell cycle and the change in the energy metabolism.
15

Avaliação de alterações proteômicas em diferentes modelos de indução da transição epitelial-mesenquimal (EMT) em células de adenocarcinoma de mama / Proteomic alterations in different models of epithelial-mesenchymal transition (EMT) induction in breast adenocarcinoma cells

Camila de Souza Palma 29 October 2018 (has links)
O desenvolvimento tumoral é um processo que compreende diversas etapas e consiste no desenvolvimento progressivo de células normais para um estado neoplásico através de diversas mudanças bioquímicas e fenotípicas. Entre as principais marcas do câncer estão a capacidade de invasão tecidual e metástase. A metástase é responsável por, aproximadamente, 90% das mortes causadas por câncer. Assim, os métodos mais efetivos para a melhoria dos índices de morbidade e mortalidade relacionados ao câncer são a detecção precoce, a prevenção e o tratamento da metástase. O processo de EMT, que ocorre naturalmente durante a embriogênese e reparo tecidual, está envolvido também na progressão e metástase do câncer. A EMT induz alterações celulares e microambientais complexas que resultam na aquisição de um fenótipo mesenquimal pelas células epiteliais, juntamente com um aumento das capacidades migratórias e invasivas celulares. A EMT pode ser induzida por diversos fatores extracelulares, como os fatores de crescimento TGF?, EGF, HGF e PDGF. Além disso, a superexpressão de fatores de transcrição como SNAIL, SLUG, ZEB1 e TWIST1 também é capaz de induzir a EMT in vitro. A fim de ampliar o conhecimento dos mecanismos envolvidos no processo de EMT a nível de proteínas, foram realizadas neste trabalho análises de alterações proteômicas em diferentes modelos de indução da EMT na linhagem de adenocarcinoma de mama MCF7, sendo eles a superexpressão do FT SNAIL, o tratamento com o inibidor de histonas deacetilases SAHA e o tratamento com o fator de crescimento EGF. A análise proteômica detalhada por LC-MS/MS das frações subcelulares de núcleo, citoplasma e membrana das células superexpressando SNAIL gerou uma lista de proteínas reguladas relacionadas com o processo de EMT e que foram avaliadas nos demais modelos de indução. Entre essas, a proteína HDAC1, que teve seus níveis diminuídos pela superexpressão de SNAIL. O tratamento da linhagem MCF7 com o inibidor de histonas deacetilases SAHA demonstrou uma correlação positiva com o aumento dos níveis de SNAIL nas células MCF7, sugerindo um cross-talk entre ambas as proteínas. Além disso, otratamento com SAHA induziu alterações celulares e proteicas que também sugerem a indução do processo de EMT nas células MCF7. Por fim, o tratamento com o fator de crescimento EGF também foi capaz de induzir a EMT nas células MCF7 e apresentou envolvimento na regulação do ciclo celular, alterações de proteínas em comum com os demais tratamentos e regulação diferencial de proteínas entre os subcompartimentos, indicando similaridades entre os processos e potenciais mecanismos de translocação subcelular. Em conclusão, este estudo relevou proteínas alvo relacionadas à EMT, abrindo possibilidades para tentar alterar processos relacionados à progressão tumoral e ao processo metastático. / Tumor development is a process comprising several steps and consists in the progressive development of normal cells into a neoplastic state through various biochemical and phenotypic changes. Among the major marks of cancer are the capacity for tissue invasion and metastasis. Metastasis accounts for approximately 90% of cancer deaths. Thus, the most effective methods for improving cancer-related morbidity and mortality rates are early detection, prevention and treatment of metastasis. The EMT process, which occurs naturally during embryogenesis and tissue repair, is also involved in cancer progression and metastasis. EMT induces complex cellular and microenvironmental changes that result in the acquisition of a mesenchymal phenotype by epithelial cells, together with an increase in migratory and invasive cellular capacities. EMT can be induced by various extracellular factors, such as TGF?, EGF, HGF and PDGF. In addition, overexpression of some transcription factors such as SNAIL, SLUG, ZEB1 and TWIST1 is also capable of inducing EMT in vitro. In order to increase the knowledge of the mechanisms involved in the EMT process, we performed proteomic analysis in different models of EMT induction in the MCF7 breast adenocarcinoma cell line, which were the overexpression of SNAIL, treatment with the histone deacetylase inhibitor SAHA and treatment with the growth factor EGF. The detailed proteomic analysis by LC-MS/MS of the subcellular fractions of nucleus, cytoplasm and membrane of the overexpressing SNAIL cells generated a list of regulated proteins related to the EMT process and that were evaluated in the other models of induction. Among these, the HDAC1 protein, which had its levels decreased by SNAIL overexpression. Treatment of the MCF7 cell line with the histone deacetylase inhibitor SAHA showed a positive correlation with the increase of SNAIL levels, suggesting a cross-talk between both proteins. In addition, SAHA treatment induced cellular and protein alterations that also suggest the induction of the EMT process in MCF7 cells. Finally, the treatment with the growth factor EGF was also able to induce the EMT in MCF7 cells and showed involvement in the regulation of the cell cycle, changes in proteins in common with the other treatments and differential regulation of proteins among thesubcompartiments, indicating similarities between the processes and potential mechanisms of subcellular translocation. In conclusion, this study revealed target proteins related to EMT, opening possibilities to try to alter processes related to tumor progression and metastatic process.
16

Aparato de importação de proteínas mitocondriais em Aspergillus fumigatus: caracterização fenotípica da deleção da menor subunidade do complexo TIM23 / Proteomic changes of the epithelial-mesenchymal transition (TMS) in cancer of ovary: involvement in cell cycle control and energy metabolism

Alinne Costa Silva 20 December 2016 (has links)
O câncer de ovário (OvCa) se destaca dentre as neoplasias ginecológicas por ser um dos mais letais e de difícil diagnóstico. O OvCa ocorre devido ao acúmulo de alterações celulares progressivas promovidas por mutações no genoma de uma célula que, consequentemente, alteram as complexas vias de regulação celular que respondem a fatores internos, como reprogramação genética, ou externos, como a resposta a fatores de crescimento, que juntamente com outras alterações moleculares favorecem a progressão e a metástase. Uma importante etapa da cascata metastática é a transição epitélio-mesenquimal (EMT), um processo bem orquestrado que resulta na perda do fenótipo epitelial e aquisição do fenótipo mesenquimal pelas células tumorais, que adquirem um caráter mais invasivo e migratório, além de se tornarem mais resistentes às drogas. A desregulação de fatores de transcrição como ZEB1, TWIST e SNAI1, vias de sinalização, microRNAs e fatores de crescimento incluindo EGF, TGF? e HGF podem desencadear a EMT. Após a eficiente indução da EMT com EGF na linhagem epitelial de adenocarcinoma de ovário humano Caov-3, foi realizada a análise proteômica quantitativa detalhada, baseada na análise de frações subcelulares enriquecidas em proteínas de membrana, citosol e núcleo, obtidas por centrifugação diferencial e subsequente fracionamento de proteínas por SDS-PAGE, a fim de compreender mais profundamente os mecanismos moleculares modulados pela EMT no OvCa. A partir da análise dos dados coletados em um sistema de espectrometria de massas de alta resolução acoplados a cromatografia líquida (LCMS/MS) e com o auxílio da bioinformática foram identificadas redes de interação proteína-proteína diferencialmente expressas, relacionadas principalmente com a regulação do ciclo celular e do metabolismo. A indução da EMT por EGF resultou na ativação de importantes vias de sinalização, tais como PI3K/Akt/mTOR e Ras/MAPK Erk, além da parada do ciclo celular na fase G1 regulada pelo aumento dos níveis de p21Waf1/Cip1, independentemente de p53, e diminuição de proteínas checkpoint. Através da proteômica dirigida, o monitoramento de reações múltiplas (MRM) revelou que, após a indução da EMT por EGF, o metabolismo das células Caov-3 foi alterado de uma maneira bastante peculiar. O estudo proteômico descrito permitiu a correlação entre processo da EMT induzido por EGF com o controle translacional, a regulação do ciclo celular e a alteração do metabolismo energético. / Ovarian cancer (OvCa) stands out among gynecological malignancies for being one of the most lethal and difficult to diagnose. OvCa occurs due to the accumulation of progressive cell changes promoted by mutations in the cell genome which, consequently, alter the complex cellular regulation pathways that respond to internal factors, such as genetic reprogramming, or external, such as response to growth factors, which together with other molecular changes favor the progression and metastasis. An important step of the metastatic cascade is the epithelial-mesenchymal transition (EMT), a well-orchestrated process that results in the loss of epithelial phenotype and acquisition of mesenchymal phenotype by tumor cells that acquire a more invasive and migratory character, and become more resistant to drugs. Deregulation of transcription factors such as ZEB1, TWIST and SNAI1, signaling pathways, microRNAs and growth factors including EGF, TGF? and HGF can trigger EMT. After an efficient EMT induction by EGF in the epithelial cell line of human adenocarcinoma ovarian Caov-3, detailed quantitative proteomic analysis was performed based on analysis of subcellular fractions enriched in proteins from membrane, cytosol and nucleus, obtained by differential centrifugation and subsequent fractionation of proteins by SDS-PAGE, in order to understand deeply the molecular mechanisms modulated by EMT in OvCa. From the analysis of data collected in a highresolution mass spectrometry system coupled to liquid chromatography (LC-MS/MS) and with the aid of bioinformatics were identified protein-protein interaction networks differentially expressed, mainly related to regulation cell cycle and metabolism. EGF induced-EMT resulted in the activation of major signaling pathways such as PI3K/Akt/mTOR and Ras/MAPK Erk, in addition to G1 phase cell cycle arrest regulated by increased levels of p21Waf1/Cip1, regardless of p53, and reduction of checkpoint proteins. Through the targeted proteomics, multiple reaction monitoring (MRM) showed that after EGF induced-EMT, Caov-3 cells metabolism was changed in a very particular way. The proteomic study described allowed the correlation between EMT process induced by EGF with translational control, regulation of cell cycle and the change in the energy metabolism.
17

Avaliação de alterações proteômicas em diferentes modelos de indução da transição epitelial-mesenquimal (EMT) em células de adenocarcinoma de mama / Proteomic alterations in different models of epithelial-mesenchymal transition (EMT) induction in breast adenocarcinoma cells

Palma, Camila de Souza 29 October 2018 (has links)
O desenvolvimento tumoral é um processo que compreende diversas etapas e consiste no desenvolvimento progressivo de células normais para um estado neoplásico através de diversas mudanças bioquímicas e fenotípicas. Entre as principais marcas do câncer estão a capacidade de invasão tecidual e metástase. A metástase é responsável por, aproximadamente, 90% das mortes causadas por câncer. Assim, os métodos mais efetivos para a melhoria dos índices de morbidade e mortalidade relacionados ao câncer são a detecção precoce, a prevenção e o tratamento da metástase. O processo de EMT, que ocorre naturalmente durante a embriogênese e reparo tecidual, está envolvido também na progressão e metástase do câncer. A EMT induz alterações celulares e microambientais complexas que resultam na aquisição de um fenótipo mesenquimal pelas células epiteliais, juntamente com um aumento das capacidades migratórias e invasivas celulares. A EMT pode ser induzida por diversos fatores extracelulares, como os fatores de crescimento TGF?, EGF, HGF e PDGF. Além disso, a superexpressão de fatores de transcrição como SNAIL, SLUG, ZEB1 e TWIST1 também é capaz de induzir a EMT in vitro. A fim de ampliar o conhecimento dos mecanismos envolvidos no processo de EMT a nível de proteínas, foram realizadas neste trabalho análises de alterações proteômicas em diferentes modelos de indução da EMT na linhagem de adenocarcinoma de mama MCF7, sendo eles a superexpressão do FT SNAIL, o tratamento com o inibidor de histonas deacetilases SAHA e o tratamento com o fator de crescimento EGF. A análise proteômica detalhada por LC-MS/MS das frações subcelulares de núcleo, citoplasma e membrana das células superexpressando SNAIL gerou uma lista de proteínas reguladas relacionadas com o processo de EMT e que foram avaliadas nos demais modelos de indução. Entre essas, a proteína HDAC1, que teve seus níveis diminuídos pela superexpressão de SNAIL. O tratamento da linhagem MCF7 com o inibidor de histonas deacetilases SAHA demonstrou uma correlação positiva com o aumento dos níveis de SNAIL nas células MCF7, sugerindo um cross-talk entre ambas as proteínas. Além disso, otratamento com SAHA induziu alterações celulares e proteicas que também sugerem a indução do processo de EMT nas células MCF7. Por fim, o tratamento com o fator de crescimento EGF também foi capaz de induzir a EMT nas células MCF7 e apresentou envolvimento na regulação do ciclo celular, alterações de proteínas em comum com os demais tratamentos e regulação diferencial de proteínas entre os subcompartimentos, indicando similaridades entre os processos e potenciais mecanismos de translocação subcelular. Em conclusão, este estudo relevou proteínas alvo relacionadas à EMT, abrindo possibilidades para tentar alterar processos relacionados à progressão tumoral e ao processo metastático. / Tumor development is a process comprising several steps and consists in the progressive development of normal cells into a neoplastic state through various biochemical and phenotypic changes. Among the major marks of cancer are the capacity for tissue invasion and metastasis. Metastasis accounts for approximately 90% of cancer deaths. Thus, the most effective methods for improving cancer-related morbidity and mortality rates are early detection, prevention and treatment of metastasis. The EMT process, which occurs naturally during embryogenesis and tissue repair, is also involved in cancer progression and metastasis. EMT induces complex cellular and microenvironmental changes that result in the acquisition of a mesenchymal phenotype by epithelial cells, together with an increase in migratory and invasive cellular capacities. EMT can be induced by various extracellular factors, such as TGF?, EGF, HGF and PDGF. In addition, overexpression of some transcription factors such as SNAIL, SLUG, ZEB1 and TWIST1 is also capable of inducing EMT in vitro. In order to increase the knowledge of the mechanisms involved in the EMT process, we performed proteomic analysis in different models of EMT induction in the MCF7 breast adenocarcinoma cell line, which were the overexpression of SNAIL, treatment with the histone deacetylase inhibitor SAHA and treatment with the growth factor EGF. The detailed proteomic analysis by LC-MS/MS of the subcellular fractions of nucleus, cytoplasm and membrane of the overexpressing SNAIL cells generated a list of regulated proteins related to the EMT process and that were evaluated in the other models of induction. Among these, the HDAC1 protein, which had its levels decreased by SNAIL overexpression. Treatment of the MCF7 cell line with the histone deacetylase inhibitor SAHA showed a positive correlation with the increase of SNAIL levels, suggesting a cross-talk between both proteins. In addition, SAHA treatment induced cellular and protein alterations that also suggest the induction of the EMT process in MCF7 cells. Finally, the treatment with the growth factor EGF was also able to induce the EMT in MCF7 cells and showed involvement in the regulation of the cell cycle, changes in proteins in common with the other treatments and differential regulation of proteins among thesubcompartiments, indicating similarities between the processes and potential mechanisms of subcellular translocation. In conclusion, this study revealed target proteins related to EMT, opening possibilities to try to alter processes related to tumor progression and metastatic process.
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Ação da Proteína Kinase C na maturação de oócitos bovinos / Role of Protein Kinase C on bovine oocyte maturation

Everton Lopes 28 June 2012 (has links)
A qualidade do oócito é um fator limitante na fertilidade das fêmeas e reflete seu intrínseco potencial ao desenvolvimento embrionário subsequente. As alterações moleculares e bioquímicas no processo de maturação dos oócitos são necessárias para permitir a fecundação destes. Sob influência das gonadotrofinas, uma cascata de eventos é desencadeada, alterando a expressão gênica e a estrutura dos folículos. A maturação ocorre pelo intercâmbio entre o oócito e as células do cumulus que irão fornecer fatores para o desenvolvimento do oócito e criar o microambiente necessário para garantir o sucesso na maturação. A ação do FSH sobre a retomada da meiose ocorre, possivelmente, por ativação da proteína quinase C (PKC). A via de sinalização desta proteína parece estar envolvida na ativação da quinase ativada por mitógeno (MAPK) em oócitos e células do cumulus, na maturação induzida por FSH e LH, além de regular a síntese do Fator de Crescimento Epidermal (EGF). Deste modo, o objetivo do presente trabalho foi avaliar a ação da PKC na maturação de oócitos bovinos e se esta ativação envolve o EGF. Para tal foram realizados dois experimentos. Em ambos, a progressão do ciclo celular foi avaliada utilizando a sonda fluorescente Hoechst 33342. A expansão das células do cumulus foi avaliada utilizando-se o software Image Pro Plus 5.1 para análise das imagens dos oócitos geradas em microscópio Olympus IX81. O maior diâmetro de cada complexo cumulus oócito foi adotado como parâmetro de mensuração da expansão. A dosagem de progesterona do meio de cultivo foi realizada pela técnica de RIA. A ativação da PKC e da MAPK foi avaliada pela técnica de Western blot. Os dados foram avaliados pelo software SigmaPlot versão 12.2 e submetidos ao teste de normalidade (Shapiro-Wilk). Quando necessário, os dados foram transformados. Para comparação entre dois tratamentos, utilizou-se o teste t-student. Para mais de dois tratamentos foi realizada análise de variância e teste de comparação de médias (TUKEY), considerando-se 0,05 para rejeitar a hipótese de nulidade. No experimento 1 foi avaliado se a ativação da PKC foi estimulada por gonadotrofinas. Os oócitos foram maturados in vitro tratados com gonadotrofinas, na presença ou ausência do inibidor de PKC. A presença do inibidor de PKC diminuiu as taxas de quebra de vesícula germinativa e a expansão das células do cumulus, sem alterar a esteroidogênese. Estes resultados demonstram que a PKC participa da via de sinalização da retomada da meiose. No experimento 2 foi avaliado se o EGF está envolvido na via regulada pela PKC. Os oócitos foram maturados in vitro, na presença ou ausência de LH e FSH, do inibidor de PKC e do EGF. O EGF foi capaz de reverter os efeitos do inibidor de PKC, aumentando as taxas de quebra de vesícula germinativa e a expansão de células do cumulus. Não foi possível detectar, nas condições deste experimento, a ativação das proteínas PKC e MAPK através do Western Blot. Este trabalho permite concluir que a via de sinalização da maturação de oócitos bovinos envolve a PKC e sugere a participação do EGF nesta via. / Oocyte quality is a limiting factor in female fertility and reflects its potential to the subsequent embryonic development. Molecular and biochemical alterations during the oocyte maturation process are needed to allow fecundation. Under gonadotropin influence, cascade of events occurs changing gene expression and follicle structure. Maturation depends on the interaction between oocyte and cumulus cells interaction, which provides factors for oocyte development and create the ideal microenvironment for the success of the maturation process. The FSH stimulation of meiosis resumption probably occurs through PKC activation. The signaling pathway of PKC might be involved by the mitogen activated protein kinase (MAPK) in oocytes and cumulus cells during FSH-LH induced maturation. Furthermore, MAPK regulates the epidermal growth factor (EGF) synthesis. The aim of the present study was to evaluate PKC function during bovine oocyte maturation and if its activity involves EGF. Two experiments were performed. In both experiments, the cell cycle progression was analyzed by Hoechst 33342 fluorescent dye. The cumulus cells expansion was performed using software Image Pro Plus 5.1 by the analysis of oocyte images taken in Olympus IX81 microscope. The highest diameter of each cumulus oocyte complex was recorded as the expansion value. The RIA and Western Blot techniques were used to measure progesterone concentration in the culture media and the PKC and MAPK activity, respectively. Data was analyzed by SigmaPlot software, version 12.2. The Shapiro-Wilk test was used to assess for normality and, when needed, the data was transformed. Student t tests were carried out to compare two treatments. Differences between more than two means were assessed by analysis of variance followed by Tukey test, considering P-value lower than 0.05 as statistically significant. Experiment 1 studied whether PKC function was stimulated by gonadotropins. FSH and LH were used for oocyte maturation in vitro, with or without PKC inhibitor. The presence of PKC inhibitor decreased germinal vesicle breakdown and the cumulus cells expansion, but did not alter the steroidogenesis. These results show that PKC participates in the signaling pathway of meiosis resumption. The Experiment 2 evaluated whether EGF influences PKC signaling pathway. The oocytes were matured in vitro, in the presence or absence of LH and FSH, PKC inhibitor and EGF. Epidermal Growth Factor was able to reverse PKC inhibitor effects, increasing germinal vesicle breakdown rates and cumulus cells expansion. The Western Blot technique was not able to detect PKC and MAPK activity, considering the conditions of this study. In conclusion, PKC is involved in the signaling pathway of bovine oocytes maturation and its pathway is mediated by EGF.
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Mechanismus regulace aktivace ligandů EGF receptoru prostřednictvím intramembránové pseudoproteasy iRhom a metaloproteasy ADAM17 / Mechanism of regulation of EGFR receptor ligand activation via the intramembrane pseudoprotease iRhom and cell surface metalloprotease ADAM17

Trávníčková, Květa January 2019 (has links)
Signalling through the EGF receptor is subject to a complex and multilayered regulation. One such mode of regulation is through control of ligand production which plays an important role in fine- tuning EGF receptor activation. In mammals, the production of soluble, biologically active forms of EGF receptor ligands relies on ADAM metalloproteases, predominantly ADAM10 and ADAM17. Recently, a pseudoprotease from the rhomboid-like family of intramembrane proteases, iRhom, emerged as a key positive regulator of ADAM17. However, Drosophila iRhom has also been implicated in the negative regulation of EGF receptor signalling by promoting the degradation of precursors of its ligands. Cell culture based assays suggest that mammalian iRhoms might also be involved in a similar process. In this thesis, the effect of mammalian iRhom overexpression on the levels of EGF receptor ligands has been investigated. Contrary to previous findings, the data presented in this thesis suggest that the observed effect might not be entirely iRhom specific, for the inactive mutants of rhomboid proteases also diminish the levels of EGF receptor ligands. Nor do we find the effect to be specific to EGF receptor ligands, as unrelated transmembrane proteins were also depleted by iRhom overexpression. The coexpression of ADAM17 was...
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Role of Confinement on Clathrin-mediated Endocytosis / Role du confinement sur l'endocytose dépendante de la clathrine

Le devedec, Dahiana 17 September 2019 (has links)
L’endocytose dépendante de la clathrine (EDC) est la principale voie d’internalisation des récepteurs de surface et de leurs ligands. L’internalisation se fait suite à l’invagination de la membrane plasmique vers l’intérieur de la cellule suite à la formation, dans un premier temps, de puits recouverts de clathrine (PRCs) qui bourgeonnent ensuite en vésicules recouvertes de clathrine dans le cytosol. L’EDC est un processus très dynamique qui a lieu en l’espace de 30 sec-1mn. Elle est impliquée dans de multiples fonctions et permet ainsi à la cellule de réguler l’expression de ses protéines en surface, de répondre aux signaux de prolifération ou migration envoyés par l’environnement immédiat via l’activation de voies de signalisation spécifiques ou encore de réguler le renouvellement des composants de la membrane plasmique. De par son importance, des dérégulations de l’endocytose dépendante de la clathrine ont déjà été observées dans les cancers. Ces modifications peuvent impliquer directement l’EDC en modifiant ses composants ou indirectement lors d’altérations de récepteurs régulés par celle-ci. La progression tumorale est elle-même régulée par de multiples facteurs, notamment l’accumulation de mutations qui ont des conséquences sur les cellules cancéreuses elle-même ou bien sur l’environnement immédiat, formant ainsi la « niche tumorale ». Ces changements agissent réciproquement sur la progression tumorale afin de l’amplifier. Lors de la croissance tumorale, les cellules cancéreuses recrutent des fibroblastes qui vont participer au remodelage et à l’augmentation de la rigidité autour de la tumeur. La rigidité de la matrice extracellulaire est détectée par les cellules ce qui envoie des signaux déclencheurs de prolifération et de migration en conséquence. Cette détection passe essentiellement par les intégrines à la surface membranaire qui vont s’agréger et induire des cascades de signalisation impliquées dans ces réponses. Ces intégrines peuvent se regrouper dans deux types de structures, les adhésions focales et les structures recouvertes de clathrine. En ce qui concerne ces dernières, il a été démontré précédemment que la rigidité du substrat augmente sa force d’interaction avec les intégrines, et empêche ainsi l’internalisation des vésicules recouvertes de clathrine, on parle alors d’ « endocytose frustrée ». Cette rétention des structures recouvertes de clathrine à la surface provoque une signalisation soutenue à la surface au lieu de l’arrêter par dégradation ultérieure des récepteurs dans les lysosomes. Le laboratoire a démontré que les structures de clathrine frustrées capturent ainsi différent récepteurs conduisant à une signalisation accrue dans la voie de la MAP Kinase Erk. Mon projet de thèse repose sur ces observations en s’intéressant plus particulièrement au rôle d’une autre modification induite par la croissance tumorale, le confinement. En effet, en se multipliant de manière incontrôlée dans un environnement spatialement restreint, les cellules tumorales se retrouvent soumises à des forces de compression. Les résultats mis en évidence au cours de ma thèse ont montré que le confinement provoque, comme la rigidité, une frustration des structures de clathrine qui ne sont donc plus capables de soutenir l’endocytose des récepteurs. De plus, la compression cellulaire induit le clivage d’un pro-ligand de l’EGFR, le HB-EGF, ce qui conduit à l’activation paracrine de l’EGFR et à l’activation de la voie Erk. En effet, l’absence de facteurs de croissance dans le milieu ainsi que l’inhibition de ce clivage démontrent la nécessité de la mise en place de ce mécanisme. En résumé, le confinement induit le clivage du pro-ligand HB-EGF, qui à son tour va activer le récepteur à l’EGF. En parallèle, l’endocytose est ralentie et provoque une signalisation accrue à la membrane. Ces deux évènements coopèrent pour mener à une très forte activation de la voie Erk. / Clathrin-mediated endocytosis (CME) is the major route of endocytosis for many cargos in eukaryotic cells. Endocytosis takes place at clathrin-coated pits (CCPs), small assemblies of clathrin and clathrin adaptors randomly distributed at the plasma membrane. Clathrin polymerization induces the progressive bending of the plasma membrane resulting in the formation of a vesicle budding off into the cytosol. CME is a highly dynamic process with an average lifetime of CCPs in the order of 30 seconds. In this manner, CME fulfills a range of different functions and enables cells to regulate the surface expression of proteins, to sample the cell’s environment for growth and guidance cues, to control the activation of signaling pathways and to turn over membrane components by sending these components for degradation in the endo-lysosomal pathway. A deregulation of the endocytic pathways was previously shown to be involve in cancer. These modifications can affect CME directly by modifying its actors, or indirectly with mutations on receptors or cargoes undertaken by CME. Tumor progression is dependent of several factors, the first one involving the accumulation of mutations which results in modifications in the cells themselves or on their surrounding environment by changing its biochemical and physical properties, leading to the formation of the tumor niche. These changes reciprocally foster cancer progression. During tumor growth, fibroblasts will be recruited around tumor cells, leading to the remodeling of the microenvironment and to an increase of rigidity nearby the tumor. This stiffness is sensed by the cells and send signals for proliferation and migration as a result. Stiffness sensing engages mainly integrins at the cell surface which will aggregate and initiate signaling cascades accountable for these responses. Integrins are capable of clustering into two types of structures: focal adhesions and clathrin-coated structures (CCSs). Regarding CCSs, it was shown previously that high stiffness strengthen the interaction between integrins and the substrate, hence preventing the budding off of the vesicle, and this is referred to as “frustrated endocytosis”. This holding of CCSs at the cell surface promotes a sustained signaling at the plasma membrane instead of a signal termination after internalization and further degradation in lysosomes. My PhD project relied on these previous findings, with a particular focus on another mechanical alteration observed in tumors, the confinement. Indeed, during the uncontrolled proliferation of cancer cells in a spatially restricted area, cells become subjected to compressive forces. The results I obtained indicate that confinement leads to frustrated endocytosis and hence to sustained signaling from the plasma membrane. In addition, compression also leads to HB-EGF shedding at the cell surface, and the resulting EGF product activate the EGFR in a paracrine manner, thus leading to the activation of the MAP kinase Erk signaling pathway. Indeed, both the absence of EGFR ligands in the medium and the inhibition of the shedding demonstrate the necessity of this mechanism in EGFR activation. To sum up, confinement induces the shedding of the EGFR pro-ligand HB-EGF necessary to EGFR activation in these conditions. Simultaneously, endocytosis is delayed and frustrated endocytosis leads to sustained signaling at the cell surface. Together, these events cooperate to strongly activate the Erk pathway. These findings highlight the interplay between the physical feature of the tumor environment and signaling pathways known to govern tumor growth.

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