La FAK est une tyrosine kinase cytoplasmique qui régule divers processus cellulaires, dont la survie, la prolifération, la différenciation et la motilité. Bien que diverses études aient démontré l'importance du FAK dans la pathogenèse du SMD et de la LAM, le rôle de cette molécule dans le microenvironnement des tumeurs du SMD et de la LAM reste à déterminer davantage. En examinant les CSM de la moelle osseuse qui dérivent de patients atteints de SMD et de LAM, nous avons observé une augmentation continue de l'expression et de l'activation de la FAK pendant la progression du SMD vers de la LAM, semblable à celle observée chez les patients hémopoïétiques. Dans le SMD à faible risque, on a constaté que les CSM se caractérisaient par une faible expression et une faible activation du FAK. Ils présentaient une morphologie modifiée, un immunophénotype, une différenciation et l'expression de facteurs favorables à l'hématopoïèse. Il convient de noter que ces caractéristiques pourraient être largement reproduites dans les CSM saines par inhibition FAK. De plus, l'appauvrissement en FAK dans la lignée cellulaire stromale pourrait induire une expansion massive et l'apoptose des CSH normaux. Nos résultats mettent en évidence le rôle crucial du FAK dans le maintien des fonctions des CSM et fournissent la preuve que la dysrégulation du FAK dans les CSM contribue à la perturbation de l'hématopoïèse et éventuellement à la progression des tumeurs malignes myéloïdes. Une meilleure compréhension du rôle que joue le microenvironnement du SMD et de la LAM permettra de mieux reconnaître les patients à faible risque et de mettre au point des traitements ciblant les CSM défectueuses, améliorant ainsi le résultat clinique / FAK is a cytoplasmic tyrosine kinase that regulates diverse cellular processes, including survival, proliferation, differentiation, and motility. Though various studies have demonstrated the importance of FAK in MDS and AML pathogenesis, the role of this molecule in MDS and AML tumor microenvironment remained to be further determined. By examining BM MSCs derived from MDS and AML patients, we have observed a continues increase of FAK expression and activation during MDS progression to AML, similar to those detected in hemopoietic counterparts. In LR-MDS, MSCs were found to be characterized by low FAK expression and activation. They exhibited altered morphology, immunophenotype, differentiation, and expression of hematopoiesis-supporting factors. Of note, these features could be largely reproduced in normal MSCs by FAK inhibition. Furthermore, FAK depletion in BM stromal cell line could induce massive expansion and apoptosis of normal HSPCs. Our results highlight a critical role of FAK in maintaining the functions of BM MSCs and provide evidence that dysregulation of FAK in MSCs contribute to the disturbed hematopoiesis and possibly the progression of myeloid malignancies. A greater understanding of the role that BM microenvironment plays in MDS and AML will enable an increased recognition of poor-risk patients and the development of therapies that target the defected MSCs, thereby improving the clinical outcome

Focal adhesion kinase (FAK) is a non-receptor tyrosine kinase. Activated FAK is crucial to many biological processes, such as cell proliferation, migration, and survival, all of which have been implicated in the progression and development of cancer. Tyrosine 925 is a Src-phosphorylation site that is located within the FAT domain in the C-terminal of FAK. It has been suggested that the helix containing Y925 (Helix 1) has to come out of the FAT bundle and the region flanking Y925 has to adopt β-strand conformation. In order to phosphorylate, the mechanisms promoting the required structural changes are unclear. So, Molecular Dynamics (MD) and Constant Force Molecular Dynamics (CFMD) simulations were used to study what makes Y925 accessible for phosphorylation. Under thermal fluctuation only and in the presence or the absence of LD motifs, MD simulations suggest that H1 does not appear to have a propensity to leave the bundle adopt β-strand conformation. Then, two different load scenarios were used; axial and perpendicular with 100 pN constant load applied to H1 N-terminus with the two paxillin LD motifs constrained. For both load scenarios, H1 has two different behaviors: typical and atypical. In the axial load scenario, the first two residues at the N-terminal of H1 (besides Y925) have low propensity to unfold. However, H1 does not show any proclivity to leave the bundle. For the perpendicular load scenario with the absence of P2 (LD motif binds to H1/H4 hydrophobic patch), one simulation out of 21 showed that H1 undergoes the required structural rearrangement. In general, CFMD simulations show that the FAT domain has a very low propensity (3%) to undergo the structural changes needed for Y925 phosphorylation. This has two implications: either mechanical load is insufficient to make Y925 available for phosphorylation and/or this kind of process (structural changes needed for Y925 phosphorylation) is slow process that needs a long time to occur. / text

The role that signaling molecules play during morphogenesis and their interactions is a field of intense study and the sea urchin represents a facile system to study these aspects of development in the early embryo. In many instances, the S. purpuratus genome contains relatively simple receptor-ligand signaling systems compared to vertebrate counterparts and this provides interesting opportunities to study their diversity of function during the morphogenetic events that shape the embryo. The Eph-Ephrin signaling components are an excellent example of this and they are represented by dozens of members in the vertebrate system with developmental functions that include axon guidance, cell migration and tissue segregation. In contrast, the sea urchin genome contains a single Eph receptor and a single Ephrin ligand and by interacting with different effectors of signal transduction, this simple, bipartite system can fulfill a variety of functional roles during morphogenesis. Studying the function of Eph-Ephrin signaling in the sea urchin embryo, I have revealed two distinct morphogenetic movements in which Eph-Ephrin signaling is necessary; apical constriction of ciliary band cells and pigment cell migration. In both examples, a functionally relevant Ephrin gradient establishes spatial information in the developing tissues, producing a reaction from cells expressing the Eph receptor. In the case of pigment cells, the distribution of migrating cells is affected and in the case of ciliary band cells, apical constriction occurs. The different outcomes of Eph-Ephrin signaling in these two tissues exemplifies signaling components communicating spatial information and initiating morphogenetic programs with outcomes dependent on cellular context. Furthermore, I have identified downstream components of Eph-Ephrin signaling that have necessary functions in both models, illustrating how different cellular programs can be induced by the same signaling iii iv components. My research contributes to understanding fundamental aspects of how complex 3 dimensional tissues arise from the genes and regulatory elements encoded in metazoan genomes. / Graduate

Thesis (Ph. D.)--West Virginia University, 2008. / Title from document title page. Document formatted into pages; contains x, 229 p. : ill. (some col.). Includes abstract. Includes bibliographical references.

Orientador: Kleber Gomes Franchini / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas / Made available in DSpace on 2018-08-17T19:53:30Z (GMT). No. of bitstreams: 1 Santos_AlineMarados_D.pdf: 7023687 bytes, checksum: ccd063ea57be631b6b555f86e24af597 (MD5) Previous issue date: 2011 / Resumo: A tirosino-quinase de adesão focal (FAK) tem papel crítico na mediação da migração, sobrevivência e proliferação celular. Estudos anteriores de nosso laboratório demonstraram que a FAK é ativada pelo estresse mecânico em miócitos cardíacos e que ela se coimunoprecipita com a miosina sarcomérica. No presente trabalho foi demonstrado que o domínio FERM da FAK medeia à interação com a miosina sarcomérica, sendo que esta interação leva a inibição da autofosforilação da FAK, enquanto que a ativação prévia da FAK reduz sua interação com a miosina in vitro. Ensaios de cross linking acoplado a espectrometria de massas e espalhamento de raios X a baixos ângulos demonstraram que a miosina interage em uma fenda localizada entre os subdomínios do domínio FERM. Experimentos de microscopia confocal demonstraram que estas proteínas estão colocalizadas em miócitos cardíacos de ratos neonatos e adultos. Ensaios de imunoprecipitação revelaram que aproximadamente 40% da FAK está basalmente associada à miosina sarcomérica enquanto que, após o estiramento celular esta associação reduziu paralelamente à ativação da FAK. A porcentagem de FAK associada à miosina não se alterou com a ativação da FAK após tratamento com fenilefrina, diferente da ativação pelo estresse mecânico. A interferência na interação FAK/miosina pelo silenciamento gênico da miosina culminou com a ativação da FAK e o tratamento dos miócitos cardíacos com o peptídeo FP-1, derivado do subdomínio F2 do domínio FERM, levou a uma diminuição na interação FAK/miosina e ao aumento na fosforilação/ativação da FAK. O tratamento prolongado com FP-1 resultou em hipertrofia dos miócitos cardíacos de ratos neonatos, efeito concomitante à ativação da via de sinalização Akt, TSC2 e S6Kinase. Tanto o silenciamento da FAK quanto o tratamento com rapamicina bloquearam a hipertrofia decorrente do tratamento com FP-1. Os dados deste trabalho indicam que a interação da FAK com a miosina sarcomérica é sensível ao estresse mecânico e que possui papel regulatório na manutenção da quiescência basal da FAK e no controle das vias de sinalização mediadas por esta quinase, como a via de crescimento celular AKT/mTOR/S6Kinase, em miócitos cardíacos em cultura / Abstract: The Focal Adhesion Kinase (FAK) plays a critical role in mediating the migration, survival and cell proliferation. Previous studies from our laboratory demonstrated that FAK is activated by mechanical stress in cardiac myocytes and it co-immunoprecipitate with sarcomeric myosin. Here, we demonstrated that the FAK FERM domain mediates the interaction with sarcomeric myosin, and that this interaction leads to inhibition of FAK autophosphorylation in vitro, whereas the previous activation of FAK reduces its affinity to myosin. A model based on small angle X-ray scattering analyses and crosslinking technology coupled with mass spectrometry indicated that a cleft in FERM domain is critical to the interaction of FAK to myosin. Confocal microscopy experiments showed that these proteins are colocalized in cardiomyocytes of neonatal and adult rats. Immunoprecipitation assays revealed that approximately 40% of FAK is basally associated with sarcomeric myosin while cardiomyocyte stretching reduced this association in parallel with FAK activation. The percentage of FAK associated with myosin was not change in response to FAK activation by treatment with phenylephrine, unlike in response to FAK by mechanical stress. The interference in the FAK/Myosin interaction by myosin silencing approach culminated with the activation of FAK. The treatment of cells with the FP-1 peptide, derived from the FAK FERM domain, lead to a decrease in the interaction with sarcomeric myosin and an increase in FAK activation. Prolonged treatment with FP-1 resulted in morphological hypertrophy of neonatal rat cardiomyocytes which was an effect concomitant with activation of the Akt, TSC2 and S6Kinase signaling pathway. Both FAK silencing and the rapamycin treatment blocked the morphological hypertrophy resulting of the treatment with FP-1. This study indicated that the interaction of FAK with sarcomeric myosin is sensitive to mechanical stress and it has regulatory role in maintaining of FAK quiescence and control of signaling pathways mediated by this kinase, such as cell growth via AKT/mTOR/S6Kinase in cardiac myocytes in culture / Doutorado / Biologia Estrutural, Celular, Molecular e do Desenvolvimento / Doutor em Ciências

Orientador: Kleber Gomes Franchini / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas / Made available in DSpace on 2018-08-20T13:11:14Z (GMT). No. of bitstreams: 1 Antunes_MichelleBuenodeMouraPereira_D.pdf: 4387492 bytes, checksum: bf7a9e478bc9627b01a4e45548a6f170 (MD5) Previous issue date: 2012 / Resumo: Diversos tipos celulares respondem ao estresse mecânico ativando sinais que culminam com remodelamento e sobrevivência. O estresse mecânico pode atuar como agente modulador da homeostase celular e de numerosos processos patológicos. Evidências sugerem que a Quinase de Adesão Focal (FAK) medeia a resposta de miócitos cardíacos ao estresse mecânico. Contudo, os mecanismos moleculares que regulam a função da FAK ainda não são totalmente conhecidos. No presente trabalho foi demonstrado que a small heat shock protein ?B-Cristalina interage de forma direta e protege a FAK da degradação pela calpaína 2. Ensaios de pull down, cross-linking acoplado a espectrometria de massas, mutagênese sítio dirigida, docking e modelagem molecular demonstraram que as ?-hélices 1 e 4 do domínio FAT da FAK interage no sítio de ligação constituído pelas folhas ?4 e ?8 da ?B-Cristalina. Os dados funcionais e estruturais obtidos indicaram que ocorre um aumento da associação da ?B-Cristalina e o domínio FAT da FAK após mudanças conformacionais associadas com a fosforilação dependente de Src da tirosina 925. Experimentos de pull down demonstraram que a associação com a ?B-Cristalina protege a FAK da proteólise mediada pela calpaína 2. Miócitos cardíacos submetidos ao silenciamento gênico da ?B-Cristalina apresentaram uma menor quantidade de FAK detectada em 125 KDa, indicando que esta interação protege FAK da proteólise. A submissão dessas células ao estiramento cíclico revelou uma maior taxa de morte celular por apoptose, sendo que a superexpressão da FAK restaurou a viabilidade celular. Os achados deste trabalho indicam que o complexo formado entre FAK e ?B-Cristalina apresenta papel fundamental na proteção da FAK da proteólise durante o estresse mecânico, sendo importante na manutenção da sobrevivência celular / Abstract: Cell types of diverse function respond to mechanical stress by triggering downstream signals for remodelling and survival. As such, mechanical stress impacts organismal homeostasis and numerous pathologic processes. Evidence suggests that focal adhesion kinase (FAK) mediates the responses of myocytes to mechanical stress, yet the molecular mechanisms to regulate FAK function are unclear. We find that FAK is recognized and protected from calpain-induced degradation by the small heat shock protein alpha-B crystalline (CryAB). A model based in the pull down, crosslinking technology coupled with mass spectrometry, site-directed mutagenesis, molecular docking and molecular modeling indicated that a cleft formed by ?4 and ?8 sheets of ?B-Crystalline is critical to the interaction with ?-helix 1 and ?-helix 4 of FAK. Functional and structural data indicated that CryAB binds directly the FAT domain of FAK upon changes in conformation associated with Src-dependent phosphorylation of tyrosine 925 induced by cell stretch. Pulldown assay indicated that ?B-Crystalline interacts and protects from calpain-induced degradation FAK. Cardiomyocytes depleted of CryAB show reduced FAK quantity detected in 125KDa, indicating that this interaction protects degradation of FAK. The submission of such cells to stretch cyclic revealed a higher rate of cell death via apoptosis, whereas restoration of FAK expression restored cell viability. Our findings highlight a new role for CryAB in forming a complex with FAK that is essential for regulating cardiomyocyte survival in response to mechanical stress / Doutorado / Biologia Estrutural, Celular, Molecular e do Desenvolvimento / Doutor em Ciências

Idiopathic Pulmonary Fibrosis (IPF) is a deadly disease of unknown origin, which causes 80,000 deaths every year in the US and Europe combined. Unknown etiology and late diagnosis, combined with limited treatment options, contribute to a dismal survival rate of 3-5 years post diagnosis. Although molecular mechanisms underlying IPF pathogenesis and progression have been studied for over two decades, lack of in vivo models that recapitulate chronic, progressive, and irreversible nature of IPF have contributed to limited therapeutic success in clinical trials. Currently, only two drugs, Pirfenidone and Nintedanib, are approved for IPF treatment in the US, with their efficacy yet to be completely determined. Patients with IPF often observe lung infections, alveolar collapse, and respiratory failure, which are associated with focal edema and local hypoxia and contribute to development of hypoxemia associated with acute exacerbation of IPF (AE-IPF). In my thesis, I posit that hypoxic injury to the lung epithelium can initiate profibrotic signaling that can contribute to pathogenesis and progression of pulmonary fibrosis in vitro and in vivo. In my in silico studies, I analyzed human protein kinases to identify structural peculiarities that diversify their functions and highlight central hub kinases governing cell signaling. Using this approach, I identified Focal Adhesion Kinase 1 (FAK1) as a central hub kinase contributing to cytoskeletal remodeling. My proteomics and transcriptional studies defined in vitro effect of hypoxia in activation of lung epithelial cells. Using systems biology approaches, I identified interplay between transforming growth factor – β (TGF–β) signaling, hypoxia signaling, and FAK1 signaling. Further, my studies identified Galectin-1 as a novel mediator of hypoxia-induced pulmonary fibrosis. To mimic exacerbation of PF in patients, I developed a novel mouse model of exacerbated pulmonary fibrosis using subclinical bleomycin injury with chronic hypoxia. Further, to fill the existing requirement of an in vivo model of chronic PF, I characterized a triple transgenic mouse model that conditionally activates hypoxia signaling in the lung epithelial cells and causes progressive PF over a span of 12 weeks. Lastly, I performed RNA-Seq experiments on primary AEC2s isolated from our transgenic mouse model to identify a hypoxia-mediated profibrotic role of microRNA-96 in down-regulation of PTEN, a tumor suppressor and anti-fibrotic protein. In conclusion, my studies established in vitro and in vivo roles of hypoxia in profibrotic activation of lung epithelium and identifies FAK1 and Gal-1 as key drivers of hypoxia-mediated fibrosis, which should be further evaluated in animal and human studies to determine their therapeutic potential.

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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.