INTRODUÇÃO: A ventilação mecânica é uma terapia importante, mas com possíveis complicações. Uma das mais relevantes é a lesão pulmonar induzida pelo ventilador (VILI do inglês Ventilator-induced lung injury). Devido à hiperdistensão alveolar, o pulmão inicia um processo inflamatório, com infiltrado neutrofílico, formação de membrana hialina, fibrogênese e prejuízo de troca gasosa. Nesse processo, a mecanotransdução do estímulo da hiperdistensão celular se faz através do citoesqueleto da célula e de suas interações com a matriz extracelular e com as células vizinhas. Apesar desse papel fundamental no processo da VILI, não existem estudos in vivo sobre as alterações do citoesqueleto e de suas proteínas associadas durante esse processo patológico. O objetivo desse estudo foi descrever as alterações no citoesqueleto e em duas de suas principais proteínas associadas (FAK e paxilina) durante esse processo. MÉTODOS: Nesse estudo experimental foram feitos três grupos (n = 4 6): um controle e dois ventilados por quatro horas com PEEP de 5 cmH2O. Um grupo foi ventilado com volume corrente de 8 ml/kg (BV) e o outro com 24 ml/kg (AV). Dados de mecânica respiratória foram calculados no início e no final do período experimental. Os pulmões foram avaliados por histomorfometria quanto à área proporcional de parênquima, índice de infiltrado neutrofílico e índice de edema perivascular, quanto à quantidade de fosfo-FAK, fosfo-paxilina, paxilina total, actina músculo liso e alfa-tubulina por Western Blot, quanto à imunofluorescência para paxilina total com microscopia confocal a laser e com microscopia eletrônica de transmissão. RESULTADOS: os grupos foram semelhantes nas características basais. Houve aumento da elastância dinâmica (Edin) no grupo BV e redução no grupo AV (Edin inicial e final: 0,76 ± 0,4 vs 1,02 ± 0,47 respectivamente, em cmH2O/ml; p = 0,001). Não houve diferença na área proporcional de parênquima ou índice de edema perivascular entre os grupos estudados. A ventilação mecânica induziu infiltrado neutrofílico pulmonar nos animais, tanto no grupo BV como no AV em relação ao controle (p < 0,001). O infiltrado foi mais importante no grupo AV que no BV (p = 0,003). Houve um aumento de 40% na fosfo-FAK pelo Western Blot no grupo AV em relação ao controle (p=0,069) e aumento significativo de fosfo-paxilina no grupo AV em relação ao controle (p<0,001) e ao BV (p<0,001). Não se observaram diferenças para paxilina total, actina músculo liso e alfa-tubulina. A microscopia confocal demonstrou marcação para paxilina total nos septos alveolares. A microscopia eletrônica sugeriu reorganização do citoesqueleto nas zonula adherens do grupo AV. CONCLUSÕES: A ventilação mecânica promove lesão pulmonar com infiltrado neutrofílico numa relação dose-dependente. A ventilação com alto volume corrente promove fosforilação da FAK e de paxilina. As alterações no citoesqueleto em modelo in vivo de VILI são possíveis de serem descritas utilizando-se de métodos de microscopia confocal, Western Blot e microscopia eletrônica. / INTRODUCTION: Mechanical ventilation is an important therapy, but is associated with complications. One of the most relevant is ventilator-induced lung injury (VILI). Due to alveolar hyperdistension, the lung initiates an inflammatory process, with neutrophilic infiltration, hyaline membrane formation, fibrogenesis and gas exchange impairment. In this process, cellular mechanotransduction of the overstretching stimulus is mediated through the cytoskeleton and its cell-cell and cell-matrix interactions. But, although the cytoskeleton has this important role in the pathogenesis of VILI, there are no in vivo models for the research of cytoskeletal and cytoskeleton-associated proteins modifications during this pathological process. Our objective was to describe the immunohistochemical modifications during this process on the cytoskeleton and on two of its associated proteins (FAK and paxillin). METHODS: in this experimental study, three groups (n = 4 6) were studied: a control group and two ventilated for four hours with PEEP of 5 cmH2O. One group was ventilated with tidal volume of 8 mL/kg (LV) and the other with 24 mL/kg (HV). Data of respiratory mechanics were obtained at the beginning and the end of the experimental period. The lungs were evaluated with histomorphometry for parenchymal proportional area, neutrophilic infiltrate and perivascular edema, with Western Blot for phospho-FAK, phospho-paxillin, total paxillin, alpha-smooth muscle actin and alpha-tubulin, with confocal laser scanning microscopy for total paxillin, and with transmission electron microscopy. RESULTS: the groups were similar at the baseline. Dynamic elastance (Edin) increased in LV group and decreased in HV group (Edin initial to final: 0.76 ± 0.4 vs. 1.02 ± 0.47 respectively, in cmH2O/ml; p = 0.001). There was no difference in the parenchymal proportional area or the perivascular edema in the three groups. Mechanical ventilation induced pulmonary neutrophilic infiltration, both in the LV group and the HV group in comparison with control (p < 0.001). The infiltrate was more important in the HV group than in the LV group (p = 0.003). Phospho-FAK increased 40% in the HV group in Western Blot in comparison with control (p=0.069). Phosphopaxillin increased significantly in HV group compared with control (p<0.001) and with LV (p<0.001). Total paxillin, alpha-smooth muscle actin and alpha-tubulin did not show any differences. Confocal microscopy showed total paxillin labeling at alveolar septa. Electron microscopy suggested cytoskeleton reorganization at the zonula adherens in the AV group. CONCLUSIONS: Mechanical ventilation induces pulmonary injury with neutrophilic infiltrate in a dose-dependent relationship. Ventilation with high tidal volume promotes FAK and paxillin phosphorilation. The alterations in cytoskeleton in an in vivo model of VILI are possible to be studied with confocal microscopy, Western Blot and electron microscopy.

Les cellules de Schwann sont responsables de la myélinisation du système nerveuxpériphérique. C’est un phénomène complexe et finement régulé. En effet, des altérationsde l’expression touchant les protéines de la myéline périphérique (P0 et PMP22)peuvent provoquer des pathologies comme la Charcot‐Marie‐Tooth. Par ailleurs, lescellules de Schwann subissent d’importantes modifications de leur cytosquelette aucours du processus de myélinisation.Nous avons identifié la voie Wnt/β‐caténine comme directement impliquées dansla régulation de l’expression des gènes de la myéline P0 et PMP22 à la fois in vitro maiségalement in vivo. De plus, nous avons initié la démonstration de l’implication de la voieWnt non canonique au cours de ce même processus. Par ailleurs, nous avons montré queles ligands Wnts aussi bien canoniques que non canoniques pouvaient provoquerl’allongement des extensions des cellules de Schwann. Le chlorure de lithium est uninhibiteur de la GSK3β, mimant l’activation de la voie Wnt/β‐caténine. Il provoque unimportant allongement des cellules de Schwann accompagné de profonds remaniementsde l’architecture interne. Par la suite nous nous sommes intéressés aux effets d’unelésion sur la remyélinisation. La voie Wnt/β‐caténine est réactivée par une lésion in vitrotandis que le lithium accélère la récupération fonctionnelle du battement des vibrissesde souris après pincement du nerf facial, améliore les structures de la gaine de myélineet induit l’expression des gènes de la myéline in vivo.ConclusionNotre travail a mis en évidence le rôle majeur des voies Wnt canoniques et noncanoniques dans la régulation de l’expression de gènes de la myéline et dans lecytosquelette des cellules de Schwann. / The myelination is performed by Schwann cells in the peripheral nervous system.Myelination involves the extension of large sheaths of membranes and their wrapping around axons, accompanied by the coordinated synthesis of a variety of myelin components, including myelin‐specific proteins (MPZ and PMP22).We identified the Wnt/β‐caténin pathway as an essential and direct driver of myelin gene expression and myelinogenesis. Moreover, we identified non canonical Wnt protein as regulators of myelin genes expression MPZ and PMP22. Canonical and non canonical Wnt protein elongate the Schwann cells in vitro by microtubules stabilizationmechanisms.We used lithium chloride, an inhibitor of GSK3β to test either effects on Schwann cells cytoskeleton and recovery after nerve crash in vivo. Lithium chloride provokes Schwann cells elongation and biochemicals modifications by enhencing cholesterol as we show by IR spectroscopy. Lithium chloride accelerates the recovery of the whisker mouvements after nerve crash, provokes the remyelination of sciatic neve after crush and stimulates myelin genes expression.ConclusionWe have identified Wnt pathways as direct driver of myelin genes expression and important for cytoskeleton stabolization. Our findings, open new perspectivesin the treatment of nerves demyelination by administration of GSK3βinhibitors like lithium.

INTRODUÇÃO: A prolactina é um hormônio polipeptídico que possui reconhecida ação sistêmica, principalmente no sistema reprodutor. O papel desse hormônio no desenvolvimento e na extensão do câncer da mama ainda é muito debatido. A progressão do câncer de mama em grande parte depende do movimento celular e da capacidade da célula em remodelar seu citoesqueleto de actina. Nesse processo, proteínas envolvidas na migração celular, como moesina, FAK e c-Src, são influenciadas por vários hormônios, incluindo a prolactina. O presente estudo teve por objetivo avaliar os efeitos da PRL na migração de células T47D, MCF-7 e ZR75-1 de câncer de mama, bem como os mecanismos envolvidos. MÉTODOS: As células foram cultivadas em placas de cultura com meio suplementado e divididas em oito grupos diferentes de tratamento: Grupo I (veículo); Grupo II (PRL na concentração de 25 ng/mL); Grupo III (PRL na concentração de 50 ng/mL), Grupo IV (PRL na concentração de 100 ng / mL), Grupo V (RNAi + veículo); Grupo VI (RNAi + PRL na concentração de 25 ng/mL); Grupo VII (RNAi + PRL na concentração de 50 ng/mL) e Grupo VIII (RNAi + PRL na concentração de 100 ng / mL). Nos Grupos de I a IV, a reorganização da actina do citoesqueleto foi analisada por imunofluorescência após 30 minutos do tratamento. Em todos os grupos estudados foram realizadas análise da migração horizontal com auxílio de microscopia de luz e avaliadas as expressões de Moesina, p-Moesina, FAK, p-FAK, c-Src e p-c-Src por Western Blot após 48 horas do tratamento. RESULTADOS: As células de câncer de mama expostas à prolactina apresentaram um aumento da expressão de Moesina, p-Moesina, FAK, p-FAK, c-Src e p-c-Src. Essas alterações moleculares estão associadas à reorganização da actina do citoesqueleto e ao aumento da mobilidade das células. CONCLUSÕES: Nossos dados sugerem que a prolactina aumenta a migração das células T47D, MFC-7 e ZR75-1 de câncer de mama e remodela a actina do citoesqueleto pela via de sinalização intracelular das proteínas c-Src, FAK e moesina / INTRODUCTION: Prolactin is a polypeptide hormone with a recognized systemic action mainly on reproductive physiology. The role of this hormone on breast cancer development and progression has been debated a lot yet. Breast cancer invasion largely depends on cell movement and on the ability to remodel the actin cytoskeleton. In this process, proteins involved in cell migration, such as moesin, FAK and c-Src, are influenced by a large number of hormones, such as prolactin. The present study was aimed for evaluating the effects of PRL on migration of T47D, MCF-7 and ZR75-1 breast cancer cells as well as the molecular mechanisms in this process. METHODS: The cells were cultured in dishes with supplemented medium and were divided in eight different assays: Group I (control); Group II (25ng/ml of prolactin); Group III (50ng/ml of prolactin); Group IV (100ng/ml of prolactin); Group V (RNAi + control); Group VI (RNAi + 25ng/ml of prolactin); Group VII (RNAi + 50ng/ml of prolactin); Group VIII (RNAi + 100ng/ml of prolactin). In Groups I to IV, the actin cytoskeletal reorganization was analyzed by immunofluorescence 30 minutes after the treatment. In all groups, were performed the horizontal migration analysis with light microscopy and evaluated the expression of moesin, p-moesin, FAK, p-FAK, c-Src and p-c-Src by Western blot after 48 hours of treatment. RESULTS: Breast cancer cells exposed to prolactin display an elevated moesin, p-moesin, FAK, p-FAK, c-Src and p-c-Src expression. These molecular changes are associated with the reorganization of actin cytoskeleton and increased mobility of cells. CONCLUSION: Our data suggest that prolactin enhances the migration of T47D, MFC-7 and ZR75-1 breast cancer cells through the actin cytoskeleton remodeling by intracellular signaling pathway of c-Src, FAK and moesin proteins

Centrado no carcinoma colorretal, o presente trabalho visou: 1) Estudar a distribuição das principais variáveis anatomopatológicas, pesquisando sua associação com metástase linfonodal ou hepática. 2) Com base nas eventuais associações encontradas, selecionar um conjunto de variáveis que, estudadas no tumor primário, possam predizer a presença de metástase nodal ou hepática. 3) Analisar os perfis de imunoexpressão de alguns marcadores potencialmente relacionados à citoarquitetura (queratina 7 e 20) e ao crescimento tumoral (proliferação através do Ag Ki-67 e apoptose através da queratina 18 clivada) em amostras de mucosa normal, adenocarcinoma primário, metástase linfonodal e metástase hepática, explorando suas eventuais relações com as variáveis histopatológicas e o estadio da lesão. 4) Pesquisar possíveis associações entre a expressão dos transportadores de monocarboxilato 1, 2 e 4, moléculas reguladoras do pH intracelular, e os marcadores acima relacionados e as variáveis anatomopatológicas. A casuística foi constituída por 139 adenocarcinomas colorretais, sendo 96 sem metástase hepática e 39 com metástase hepática. Os casos foram revistos e 13 variáveis anatomopatológicas foram selecionadas para fazer parte do estudo. Foram confecionados manualmente blocos de microarranjos teciduais (TMA) de mucosa normal, tumor primário, metástase linfonodal e metástase hepática, cujos cortes foram submetidos a estudo imuno-histoquímico utilizando anticorpos anti queratina 7 (K7), queratina 20 (K20), Ki-67 e queratina 18 clivada. Em 126 blocos de parafina de tumores, e 86 amostras de mucosa normal correspondentes foram submetidos a estudo imuno-histoquímico utilizando anticopos anti transportadores de monocarboxilato 1, 2 e 4 (MCT1, MCT2 e MCT 4). A presença de metástase linfonodal asociou-se estatisticamente com a presença de infiltração tumoral além da camada muscular própria (T3 ou T4) (p<0,001), presença de desmoplasia tumoral moderada / intensa (p=0,043), presença de infiltração de vasos linfáticos (p<0,001), presença de infiltração venosa (p<0,001) e presença de infiltração tumoral perineural (p<0,001). A presença de metástase hepática teve associação estatisticamente significativa com a presença de infiltração tumoral além da camada muscular própria (p = 0,004) e com a presença de bordas tumorais infiltrativas ( p=0,05). As amostras de mucosa colorretal normal apresentaram baixa freqüência de positividade para a queratina 7, o mesmo ocorrendo com os adenocarcinomas primários e as metástases linfonodais. Detectamos, entretanto, diferença estatística significante entre a maior imunoexpressão da K7 nas metástases hepáticas quando comparadas aos adenocarcinomas primários (p<0,001) e às metástases linfonodais (p=0,015). Conforme esperado a queratina 20 mostrou-se presente na quase totalidade das amostras de mucosa colorretal normal e em mais de 90% das amostras dos vários tipos de lesão aqui estudadas. A taxa de proliferação nos adenocarcinomas primários foi significantemente superior à da observada na mucosa normal (p<0,001). Não houve diferenças estatísticas entre as taxas proliferativas das amostras neoplásicas. O índice de células em apoptose foi estatisticamente significante mais elevado nos adenocarcinomas primários que na mucosa normal (p<0,001), assim como foi mais elevado nas metástases hepáticas em relação aos adenocarcinomas primários (p=0,022). Tumores maiores que 5 cm apresentaram índices apoptóticos mais elevados que aqueles menores que 5 cm (p=0,005). As expressões citoplasmática e membranosa dos MCT1 e 4 foram mais frequentes nos adenocarcinomas que nas mucosas normais (p<0,001). A expressão membranosa do MCT1 associou-se à presença de infiltração linfática (p=0,004) , infiltração sangüínea (p=0,018) e à presença de índices apoptóticos mais elevados. Em conclusão, dentre as variáveis histológicas, infiltração linfática tumoral e infiltração de vasos sangüíneos foram fatores de risco independentes para metástase linfonodal e infiltração tumoral além da muscular própria e a presença de bordas tumorais infiltrativas foram fatores de risco independentes para metástase hepática nas análises multivariadas. A queratina 7 foi mais frequentemente expressa nas metástases hepáticas que nas metástases linfonodais e adenocarcinomas primários, indicando que a aquisição da expressão da queratina 7 pode ser uma alteração tardia do citoesqueleto associada a maior agressividade do tumor. A proliferação celular marcada pelo Ag Ki-67 assim como a apoptose, marcada pela queratina 18 clivada mostraram significativo incremento do normal para o adenocarcinoma primário e suas respectivas metástases. Os MCTs foram mais expressos nos adenocarcinomas que nas mucosas normais, sugerindo possível interferência de seu papel no controle do pH intracelular nestas neoplasias / The aims of this study in colorectal carcinoma were: 1) Verify the distribution of the most important anatomopathological variables, and identifying their relationship with lymph node or liver metastasis. 2) Considering the associations obtained in the first aim, a group of variables was selected to verify the prediction of lymph node or liver metastasis. 3) Analyze the immunoprofile of both markers associated with cytoarchitecture (keratins 7 and 20) and with tumor growth (proliferation and apoptosis using Ki-67 and cleaved keratin 18, respectively) in samples of nontumoral mucosa, primary adenocarcinoma, lymph node metastasis and liver metastasis, exploring the eventual relation with anatomopathological variables and tumor stage. 4) Look for possible associations between molecules related to intracellular pH control, as monocarboxylates transporters 1, 2 and 4, and the markers above mentioned and anatomopathological variables. One hundred and thirty nine colorectal carcinomas is the universe of the casuistic, 96 of them without liver metastasis and 39 metastatic to the liver was studied. Thirteen anatomopathological variables were selected and semi-quantified. We mannualy builted tissue microarrays (TMAs) of non tumoral mucosa, primary adenocarcinoma, lymph node metastasis and liver metastasis. The histological sections from the TMAs were submmitted to immunohistochemical study using antibodies against keratin 7 (K7), keratin 20 (K20), Ag Ki-67 and cleaved keratin 18. In 126 tumor paraffin blocks, 86 of which also had non tumoral mucosa were submitted to immunohistochemical stain using antibodies against monocarboxylate transportes 1, 2 and 4 (MCT1, MCT2 e MCT 4). Lymph node metastasis was associated with tumor infiltration across muscularis propria(p<0,001), moderate / intense desmoplasia(p=0,043), lymph vessel infiltration(p<0,001), venous infiltration (p<0,001) and perineural infiltration (p<0,001). Liver metastasis was statistically associated with tumor infiltration across muscularis propria and infiltrative tumor borders ( p=0,05). Few colorectal mucosa samples, as well as primary tumor and lymph node metastasis showed immunoexpression of K7, although we found statistically significant higher immunoexpression of K7 in liver metastasis as compared with primary carcinomas (p<0,001) and with lymph node metastasis (p=0,015). As expected, K20 was expressed in more than 90% of the samples examined. Higher Ki-67 rates were found in adenocarcinoma compared with normal mucosa (p<0,001). We did not find statistical differences of proliferation rates between neoplastic samples. Apoptotic index were higher in primary adenocarcinomas than in normal mucosa ( p<0,001), and was also higher in liver metastasis than in primary adenocarcinoma (p=0,022). We also found higher apoptotic index in tumors that measured more than 5 cm (p=0,005). Membranous and cytoplasmic expression of MCTs 1 and 4 were found more frequently expressed in adenocarcinoma than in non neoplastic mucosa (p<0,001). Membranous MCT1 expression was associated with lymph vessel infiltration (p=0,004), venous infiltration (p=0,018) and with higher apoptotic index. Lymphatic vessel infiltration and venous vessel infiltration were found as independent risk factors for lymph node metastasis. Tumor infiltration across muscularis propria and infiltrative tumor borders were also independent risk factor for liver metastasis by multivariate analysis. Keratin 7 were more frequently expressed in liver metastasis samples than in lymph node metastasis and primary adenocarcinomas, indicating that the acquisition of K7 expression could be a late cytoskeleton alteration associated with higher tumor aggressiveness. Proliferation rates as well as higher frequency of apoptosis, showed increased expression from normal mucosa to primary adenocarcinoma and its respective metastasis. Finally, monocarboxylate transporters were higher expressed in adenocarcinoma samples than in normal mucosa samples indicating a probable role in the intracellular pH in colorectal neoplasia

Submitted by Natalie Mendes (nataliermendes@gmail.com) on 2015-08-04T01:30:32Z No. of bitstreams: 1 CRIS TESE FINAL.pdf: 3970188 bytes, checksum: 37240b01333f3a3c2c98ce2597450f53 (MD5) / Made available in DSpace on 2015-08-04T01:30:32Z (GMT). No. of bitstreams: 1 CRIS TESE FINAL.pdf: 3970188 bytes, checksum: 37240b01333f3a3c2c98ce2597450f53 (MD5) Previous issue date: 2015-03-13 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / The life cycle of a seed plant involves subsequent stages of development including seed formation, germination and seedling establishment. Together these stages represent the critical phase of intersection between two generations and are characterized by deep cytological, morphological, metabolic and physiological changes. Jatropha curcas L. (Euphorbiaceae) is popularly known as physic nut and produces seeds rich in oil with properties that allow its use in various industries, including the production of biodiesel. This study aimed to advance on the understanding of morphophysiological patterns and elucidate morphoanatomical adaptations involving embryogenesis, maturation, germination and seedling growth in J. curcas. Therefore, it was initially analysed and described the morphophysiological profile based on 13 stages of development and maturation associated to color of the fruit exocarp and seed coat, and description of the structures present at each stage (Chapter 1). Analysis of microtubular cytoskeleton configurations during embryogenesis showed cell cycle activity by the presence of cortical and mitotic microtubules during histodifferentiation and organogenesis, whilst it was possible to characterize a new organogenetic profile of embryogenesis revealed by the presence of a multimeristematic radicle and stomata in embryos of J. curcas seeds (Chapter 2). The multimeristematic embryos formed by a central apical meristem and four lateral meristems interconnected by a complex vascular system have revealed a new model of root formation during seed germination and seedling development, in which there is simultaneous protrusion of a larger main root and four smaller adventitious roots, all growing at the same time during the formation of the seedling root system (Chapter 3). The stomata occurred in the radicle-hypocotyl transition area, exhibited different sizes and ontogenic phases and short lifespan by degenerating during seedling development. This demonstrates it?s functioning as restricted to the simultaneous growth stage of the five roots during germination, apparently due to high demand in gas exchange and energy metabolism, and a likely evolution onto the lenticels present in the stem of this species (Chapter 4). / O ciclo de vida de uma planta com sementes envolve est?dios subsequentes de desenvolvimento, como a forma??o da semente, a germina??o e o estabelecimento da pl?ntula. Essas etapas juntas representam a fase cr?tica de interse??o entre duas gera??es e s?o caracterizadas por profundas mudan?as citol?gicas, morfol?gicas, metab?licas e fisiol?gicas. Jatropha curcas L. (Euphorbiaceae) conhecida popularmente como pinh?o-manso, produz sementes ricas em ?leo com propriedades e aplica??es em diversos setores industriais, incluindo a produ??o de biodiesel. O presente estudo teve como objetivo caracterizar padr?es morfofisiol?gicos e elucidar adapta??es morfoanat?micas envolvendo a embriog?nese, matura??o, germina??o e o crescimento de pl?ntulas de J. curcas. Para tanto, foi inicialmente analisado e descrito o perfil morfofisiol?gico baseado em 13 est?dios de desenvolvimento e matura??o, associados ? colora??o do exocarpo do fruto e do tegumento das sementes e descri??o das estruturas presentes em cada est?dio (Cap?tulo 1). A an?lise das configura??es do citoesqueleto microtubular durante embriog?nese evidenciou atividade do ciclo celular por meio da presen?a de microt?bulos corticais e mit?ticos durante a histodiferencia??o e organog?nese. Foi poss?vel caracterizar um novo padr?o organogen?tico de embriog?nese revelado pela presen?a de rad?cula multimeristem?tica e de est?matos em embri?es de sementes de J. curcas (Cap?tulo 2). Os embri?es multimeristem?ticos, providos de um meristema apical central e quatro meristemas laterais, revelaram um novo modelo de forma??o de sistema radicular durante a germina??o de sementes e desenvolvimento de pl?ntulas, em que h? protrus?o simult?nea de uma raiz principal maior e quatro ra?zes advent?cias menores, todas crescendo ao mesmo tempo, durante a forma??o inicial do sistema radicular da pl?ntula (Cap?tulo 3). Os est?matos ocorrem na ?rea de transi??o hipoc?tilo-rad?cula e exibem diferentes tamanhos e fases ontog?nicas. Estas estruturas apresentaram um curto per?odo de vida, degenerando-se durante o desenvolvimento da pl?ntula, sugerindo seu funcionamento restrito ? etapa de crescimento simult?neo das cinco ra?zes durante a germina??o, aparentemente devido ? alta demanda em trocas gasosas e metabolismo energ?tico, e uma prov?vel evolu??o para as lenticelas presentes no caule desta esp?cie (Cap?tulo 4).

La motilité des cellules est un phénomène fondamental en biologie souvent étudié sur des surfaces planes, conditions peu physiologiques. Nous avons analysé la migration cellulaire dans une matrice cellulaire 3D contenant de la fibronectine fluorescente. Nous démontrons que les cellules y sont confinées, et déforment leur environnement de manière cyclique avec une période de ~14 min avec deux centres de contractions à l’avant et à l’arrière de la cellule qui contractent avec un déphasage de ~3.5 min. Une perturbation de ces cycles entraîne une réduction de la motilité. Par l’utilisation d’inhibiteurs spécifiques, nous avons identifié l’acto-myosine comme étant l’acteur principal de ce phénomène. En imposant des contractions-relaxations locales par ablations laser, nous avons déclenché la motilité cellulaire ce qui confirme notre hypothèse. L’ensemble de cette étude met en évidence un nouveau mécanisme fondamental de dynamique cellulaire impliqué dans le mouvement des cellules. / Cell motility is an important process in Biology. It is mainly studied on 2D planar surfaces, whereas cells experience a confining 3D environment in vivo. We prepared a 3D Cell Derived Matrix (CDM) labeled with fluorescently labeled fibronectin, and strikingly cells managed to deform the matrix with specific patterns : contractions occur cyclically with two contraction centers at the front and at the back of the cell, with a period of ~14 min and a phase shift of ~3.5 min. These cycles enable cells to optimally migrate through the CDM, as perturbation of cycles led to reduced motility. Acto-myosin was established to be the driving actor of these cycles, by using specific inhibitors. We were able to trigger cell motility externally with local laser ablations, which supports this framework of two alternating contractions involved in motion. Altogether, this study reveals a new mechanism of dynamic cellular behaviour linked to cell motility.

Rho GTPases and their regulators such as guanosine exchange factors (GEFs) and GTPase activating proteins (GAPs) represent an important class of molecules controlling dendritic spine plasticity. Although they are typically described as cytoskeletal modulators, roles for the GTPases in endocytosis and cell polarity establishment have also been defined. The neuronal proteins a1- and a2-chimaerins belong to a group of Rac and Cdc42 GAPs that inactivate these GTPases; in addition to a GAP domain, the a-chimaerins share a phosphokinase C (PKC)-like C1 domain but have distinct N-terminal domains (NTDs). My project has explored the importance of specific domains of a1-chimaerin both in induction of a morphological cellular protrusion collapse phenotype ('circularisation') and in interactions with partner proteins that may help to explain the phenotype. The results described in my thesis show that a1-chimaerin possesses a previously undescribed C-terminal domain (CTD) that is indispensable for the ability of the protein to induce collapse of protrusions, and consequent circularisation, in various cell types; moreover, an intact CTD is also important for association of a1-chimaerin with its known effector EphA4, and potentially with other undefined membrane proteins, in a C1-domain- dependent manner. In addition, my results show that a1-chimaerin associates via its NTD with the Src kinase Fyn, and via its C1 domain with the NR2A subunit of the NMDA receptor. Further experiments explored a1-chimaerin effects on EphA4 and NMDA receptor cell surface expression, as well as binding to other putative partners - including the adaptor protein p35 and the polarity protein PAR6. Finally, I have shown that inhibition of a pathway involving the Rho-associated coiled-coil containing protein kinase (ROCK) reverts circularisation induced by a1- chimaerin, and that a blocking peptide based on the CTD may be employed to partially counteract the phenotype. These results uncover a novel domain in a1-chimaerin that may have a crucial importance for the induction of cellular process collapse by a1-chimaerin with a potential relevance to the EphA4-induced dendritic spine retraction, EphA4 receptor endocytosis, and cell surface expression of NR2A-containing NMDA receptors. This suggests a model of a multi-protein signalling complex involving a1-chimaerin that coordinates cellular process remodelling, and that is likely to be important both for adult neuronal circuit plasticity and for neurodegenerative diseases.

L'objet de cette thèse est l'étude comparative de la réponse de cellules saines et malignes à la micro- et la nano-topographie de surface. L'interaction avec des stries de profondeur nanométrique est étudiée grâce à une méthode statistique. Nous démontrons que les cellules saines s'alignent plutôt sur des stries profondes, et que les cellules cancéreuses sont plus sensibles aux stries peu profondes. L'analyse des noyaux révèle qu’ils suivent l'alignement des corps cellulaires plus fidèlement dans le cas des cellules cancéreuses et que les noyaux de ces dernières sont plus sensibles aux stries de faible profondeur. Sur des micro-piliers nous démontrons que les cellules d’ostéosarcomes sont capables de se déformer et de faire adopter à leurs noyaux la forme de l'espace entre les piliers. Ceci ne se produit que durant la phase initiale d'adhésion pour les cellules saines. Les cellules immortalisées présentent un niveau intermédiaire de déformation. Quand l'espacement entre piliers est réduit, des différences de déformation sont révélées entre les lignées cancéreuses testées. La déformation est aussi liée au caractère cancéreux de kératinocytes et à l'expression de Cdx2 dans des lignées d'adénocarcinomes. Nous avons tenté d'expliquer ce mécanisme de déformation en l'attribuant au cytosquelette grâce à des analyses en microscopie confocale et avec des inhibiteurs du cytosquelette. L'imagerie de cellules vivantes a permis d'observer que les cellules sont très mobiles même quand elles sont déformées, que la mitose nécessite la perte de la déformation et que la déformation après mitose est plus rapide que la déformation pendant l'adhésion initiale des cellules. / This thesis deals with the differential response of healthy and cancerous cells to surface topography at the nanoscale and the microscale. Using a statistical method we developed we studied the interactions of cells with grooves of nanoscale depth. We demonstrate that healthy cells have a greater ability to align with deeper grooves, whereas cancerous cells are more sensitive to shallow grooves. Analysis reveals that the nucleus follows the alignment of the cell body more closely in cancerous cells, and that the nucleus of cancerous cells is more sensitive to shallow grooves.On microscale pillars we demonstrate for the first time that osteosarcoma cells deform to adopt the surface topography and that the deformation extends to the interior of the cell and in particular to the nucleus. We show that healthy cells only deform during the initial stages of adhesion and that immortalized cells show intermediate deformation between the healthy and cancerous cells. When the spacing between the pillars is reduced, differences in the deformation of different cancerous cell lines are detected. Deformation was also found to be related to the malignancy in keratinocytes, and related to the expression of Cdx2 in adenocarcinoma. The mechanism of deformation is tentatively attributed to the cytoskeleton and attempts to identify the main actors of deformation were performed using confocal microscopy and cytoskeleton inhibitors. Live cell imaging experiments reveal that the deformed cells are very mobile on the surfaces, loss of deformation is necessary for mitosis to occur and deformation after mitosis is more rapid than initial deformation upon adhesion to surfaces.

Le travail présenté dans cette thèse est le résultat d'une collaboration fructueuse entre la chimie, la physique et la biologie. En effet, des matériaux avec des propriétés physico-chimiques très contrôlées ont été mis à profit dans le but de caractériser des fonctions cellulaires complexes. Nous présentons tout d'abord la création d'un outil permettant l'étude de la mécanotransduction cellulaire. L'originalité de cet outil est basé sur son activation par étirement permettant de lier réversiblement les cellules à la surface. Nous avons ensuite étudié des comportements de cellules souches et cancéreuses en réponse à des microtopographies sous forme de piliers. Cette approche a permis de définir un comportement cancéreux caractérisé par une déformation prononcée des corps et noyaux cellulaires. Nous montrons aussi que l'utilisation de cette surface couverte de micro-piliers permet de décrire la mécano-biologie de cellules cancéreuses. En effet, ce substrat à topographie contrôlée a permis de montrer que la chimie et la rigidité du substrat n'ont que peu d'incidence sur la déformation des cellules cancéreuses, alors que les éléments du cytosquelette sont primordiaux et que sans eux, la déformation n'est pas possible. Nous avons ensuite inhibé une à une des protéines de l'enveloppe et de la lamina nucléaire afin d'évaluer leur implication dans ces mécanismes de déformation. En parallèle, un séquençage total des ARN (Acides RiboNucléiques) de cellules déformées et non déformées a été réalisé dans le but de visualiser d'éventuelles modifications dans l'expression génique. Ces déformations des cellules cancéreuses entre les micro-piliers ont été comparées à celles que subissent les cellules lors de la traversée de membranes poreuses (Chambres de Boyden). Ces comparaisons nous ont permis d'identifier que plusieurs mécanismes peuvent aboutir à la déformation de cellules cancéreuses et en particulier de leurs noyaux. Nous montrons dans une dernière partie que la mitose cellulaire s'effectue sur les surfaces microstructurées. Nous décrivons une ségrégation des chromosomes qui semble être non parallèle. Toutefois, ces divisions atypiques ne causent pas davantage d'accidents mitotiques. / The work shown in this thesis is the outcome of a successful collaboration between chemistry, physics and biology. Indeed, materials with well controlled parameters have been used in order to characterize complex cellular functions. We first introduce the creation of one tool which allow the study of cells mechanotransduction. The originality of this tool is based on its activation by stretching which allow a reversible adhesion of cells to the surface.Then, we studied the behavior of stem cells and cancerous cells on micropillared surfaces. This approach allowed us to describe a cancerous behavior of cells characterized by strong deformations of cells bodies and nuclei. We also showed that the use of such micropillared surfaces allowed us to describe cancerous cells mecanobiology. Indeed, this substrate with a well controlled topography allowed us to show that substrates chemistry and stiffness have only little effects on cancerous cells deformation while cytoskeleton components are necessary. More specifically, the deformation is impossible without the cytoskeleton. We also inhibited the nuclear envelope proteins and nuclear lamina proteins in order to evaluate their involvement in cells deformation mechanism. In the same time, a total RNA (RiboNucleic Acids) sequencing of deformed and non deformed cells have been done in order to identify an eventual modification in gene expression.These deformations of cancerous cells between micropillars have been compared to the deformation of cells during the transmigration through porous membranes (Boyden chambers). These comparisons allowed us to identify several mechanisms which lead to cells deformation and more specifically to nuclei deformation.We showed in a last part that cells can divide on micropillared surfaces. We described a non parallel like segregation of chromosomes. However, these unusual mitosis didn't lead to supernumerary troubles in cell division.

Células de músculo liso vascular são capazes de perceber estímulos mecânicos do sistema cardiovascular, coordenando pressão sanguínea e perfusão tecidual por meio da modulação do tônus e do diâmetro vascular via resposta contrátil. O gatilho inicial à contração é um aumento na concentração intracelular de cálcio e diversas vias de sinalização têm sido descritas na sustentação deste sinal inicial. Evidências atuais indicam que adesões focais desempenham papel crucial na contração através da organização do citoesqueleto de actina e engajamento com o aparato contrátil. Nosso grupo demonstrou que a proteína rica em cisteína e glicina 3 (CRP3) interage com a quinase de adesão focal (FAK) em resposta a um aumento do estiramento mecânico e existem evidências de que CRP3 modula a dinâmica do citoesqueleto de actina. Neste trabalho testamos a hipótese de que a proteína CRP3 atua como uma proteína de adesão focal que regula a contração de células musculares lisas aórticas. Por meio de ensaios de imunoprecipitação e colocalização, verificou-se a presença de CRP3 nas adesões focais de células selvagens. Evidenciou-se que a ausência de CRP3 está associada a aumento no tamanho médio de adesões focais em células musculares lisas aórticas de forma independente do substrato. Entretanto, em resposta à angiotensina II, células nocaute para CRP3 apresentam incapacidade de maturação das adesões focais, um evento que está associado ao reduzido conteúdo proteico de FAK, paxilina e MLC2 (plataformas moleculares envolvidas na maturação de adesões focais) observada em células nocaute. Consistente com o maior tamanho médio das adesões focais, células nocaute são mais rígidas e, portanto, menos elásticas que células selvagens, sendo que a rigidez avaliada por citometria magnético-óptica de oscilação se reflete na reduzida capacidade contrátil, seja em condições basais, em resposta à angiotensina II ou ao inibidor de ROCK, como evidenciado no ensaio de contração em gel de colágeno. Em síntese, os dados deste trabalho mostram que CRP3 está presente nas adesões focais, regulando tamanho e sinalização, com reflexos na rigidez (viscoelasticidade) e capacidade contrátil, variáveis fundamentais ao correto funcionamento de células musculares lisas aórticas. Em conjunto, as evidências deste trabalho suportam a hipótese de que CRP3 é um modulador de contratilidade e mecanotransdução em células musculares lisas aórticas / Smooth muscle cells act also as mecanosensors of the cardiovascular system, coordinating blood pressure and tissue perfusion by means of vascular tone and diameter modulation via the contractile response. The trigger for contraction is a rise in the intracellular calcium concentration and several signaling pathways have been described to sustain the initial calcium signal. Recent evidences highlight the crucial role of focal adhesions to the contractile response, given its role in actin cytoskeleton assembly and engagement with the actomyosin contractile apparatus. We have demonstrated that the cysteine and glycine-rich protein-3 (CRP3) interacts with focal adhesion kinase (FAK) in response to increased hemodynamic stress. Additionally, it has also been shown that CRP3 modulates actin cytoskeleton dynamics. Here, we tested the hypothesis that CRP3 acts as a focal adhesion protein that regulates the contraction of aortic smooth muscle cells. Through colocalization and immunoprecipitation studies we found that CRP3 is a focal adhesion protein in aortic smooth muscle cells. Focal adhesion mean size evaluation showed that in the baseline, CRP3 KO smooth muscle cells display greater focal adhesion size. However, upon angiotensin II (a contraction-triggering molecule) stimulation, CRP3 KO cells fail to maturate focal adhesions, an event that might be related to the reduced protein levels of FAK, paxillin, and MLC2 (key signaling molecules involved in focal adhesion maturation) observed in KO cells. Consistent with the greater mean focal adhesion size, CRP3 KO cells exhibited increased stiffness and therefore, reduced viscoelasticity when compared to wild type cells. The reduced viscoelasticity of KO cells seems to influence cell contractility, as CRP3 KO cells also displayed reduced contractile response in the baseline and in response to angiotensin II. In summary, these data showed that CRP3 is present at focal adhesions, regulating their size and signaling. Thus, CRP3 at focal adhesions influences cell stiffness and contractile capacity, which are key features of smooth muscle cell physiology. Altogether, our findings support the idea that CRP3 is a key modifier of contractility and mechanotransduction in aortic smooth muscle cells