Chez Arabidopsis, la protéine RISP est détournée par le virus CaMV pour assurer, ensemble avec la protéine virale TAV, la traduction de son ARN polycistronique. RISP a été identifiée comme une cible de la voie de signalisation de TOR et il a été montré que sa phosphorylation est requise pour promouvoir la réinitiation de la traduction activée par TAV. Les résultats que j’ai obtenus suggèrent que RISP, lorsqu’elle n’est pas phosphorylée, intervient ensemble avec eIF3, au niveau du complexe de pré-initiation 43S pour recruter le complexe ternaire grâce à l’interaction entre RISP et la sous-unité b du facteur eIF2. Il s’est avéré que RISP a la capacité, lorsqu’elle est phosphorylée, d’interagir non seulement avec la protéine ribosomique eL24 mais également avec eS6. Nos résultats indiquent que la liaison entre les sous-unités ribosomiques 60S et 40S sous l’effet de RISP, est régulée par la voie de TOR et qu’elle joue un rôle important dans le contrôle de la réinitiation de la traduction. / Many factors are required to recruit the tRNAi and a 60S ribosomal subunit to the 40S ribosomal subunit preinitiation complex. This recruitment is normally strictly limited during reinitiation of translation if factors recruited during the primary translation event are shed from 40S. However, factor retention can occur during long ORF translation if the CaMV viral factor TAV is present. RISP is a downstream target of TOR and found either within the 43S preinitiation complex, if bound to eIF3, and/or attached to 60S, if phosphorylated by TOR. We show here that RISP interacts with subunit b of eIF2 before phosphorylation. Critically, TOR activation up-regulates phosphorylation of both RISP and eS6 as well as the binding of both factors. Importantly, eS6-deficient plants are less active in TAV-mediated reinitiation and are thus less susceptible to CaMV infection. It is attractive to propose that eS6 phosphorylation contributes to retention and re-use of 60S during 40S scanning.

Le virus de la fièvre catarrhale ovine (Bluetongue virus, BTV) est l’agent étiologique de la maladie du même nom, une arbovirose non contagieuse transmise aux ruminants domestiques et sauvages par l’intermédiaire de morsures de moucherons hématophages du genre Culicoides. Il existe actuellement 27 sérotypes décrits de BTV à travers le monde qui se distinguent par les pathologies qu’ils induisent et leur capacité à infecter et se propager chez leur(s) hôte(s) mammifère(s). Le premier objectif de mon projet de thèse visait à identifier les interactions cellulaires spécifiques des sérotypes 8 et 27 pour identifier des facteurs de pathogénicité/virulence et/ou de franchissement de barrière d’espèces. Pour atteindre cet objectif, l’ensemble des protéines virales du BTV a été criblé par la méthode du double-hybride en levure contre deux banques d’ADN complémentaires, l’une d’origine bovine et l’autre d’origine culicoïde. A l’issue de 70 cribles, une centaine de nouvelles interactions virus-hôtes a été mise en évidence et révèle un enrichissement pour quatre processus cellulaires : l’épissage des ARNm, les ribosomes, la SUMOylation et l’apoptose. Cette étude nous a ainsi permis de réaliser le premier interactome pour le BTV qui se poursuit au travers de multiples validations biochimiques et fonctionnelles des interactions identifiées. En parallèle de ce travail de protéomique, le second objectif de mon projet de thèse a été de déterminer l’impact du BTV sur la voie MAPK/ERK, une voie cellulaire essentielle à la prolifération et différenciation cellulaire et classiquement modulée lors d’infections virales. En plus de son rôle antagoniste sur la voie des interférons de type I, nous avons démontré la capacité de la protéine NS3 de BTV à activer la voie MAPK/ERK. En effet, nous avons démontré que NS3 a la capacité d’augmenter le niveau de phosphorylation des protéines kinases ERK1/2 mais également du facteur de traduction eIF4E. Cette fonction, qui semble être spécifique au BTV par rapport aux autres orbivirus, implique l’interaction de NS3 avec la protéine cellulaire BRAF, une protéine MAP3 kinase jouant un rôle majeur dans l’activation de la voie MAPK/ERK. L’activation cette voie par NS3 pourrait être un mécanisme de détournement de la traduction cellulaire au profit de celle du virus mais aussi constituer un élément de réponse pour expliquer l’hyper-inflammation observée dans le cas d’une infection par ce virus / Bluetongue virus (BTV) is the etiological agent of the bluetongue (BT) disease, a non-contagious arbovirus that affects a wide range of wild and domestic ruminants. It is transmitted by blood-feeding midges of the genus Culicoides. There are currently 27 serotypes described of BTV in the world that are distinguished by their differences in term of pathology/virulence and their capacity to infect and disseminate in their mammalian host(s). The first objective of my thesis project was to identify specific cellular interactions of serotype 8 and 27 to reveal new factors of pathogenicity/virulence and/or cross species barrier. To reach this goal, all the proteins encoded by BTV were used as baits to screen, by a high-throughput yeast two-hybrid (Y2H) approach, two complementary DNA libraries originating from hosts naturally infected by BTV : Culicoides and cattle. Therefore, 70 screens were performed to identify a hundred of new virus-host interactions and reveal an enrichment for four cellular processes : mRNA splicing, ribosomes, SUMOylation and apoptosis. This study allowed us to build the first interactome of BTV which continues through multiple biochemical and functional validations of the identified interactions. In parallel to this proteomics work, my second objective was to determine the impact of BTV on the MAPK/ERK pathway, a cellular pathway essential for cell proliferation and differentiation usually modulated during viral infections. In addition to its antagonist role on the type I interferon pathway, we have demonstrated the ability of BTV-NS3 to activate the MAPK/ERK pathway. Indeed, we have demonstrated that NS3 has the ability to increase the level of phosphorylation of ERK1/2 protein and the eIF4E translation factor. This function, which seems to be specific to BTV compared to other orbiviruses, involves the interaction of NS3 with BRAF cellular protein, a MAP3 kinase protein that plays a major role in the regulation of the MAPK/ERK pathway. These results could provide a better understanding of the molecular basis underlying the hijacking of the translation machinery to support virus replication but also constitute a hypothesis to explain the hyperinflammation observed in the BTV infection context

O Tumor Odontogênico Queratocístico (TOQC) é considerado uma entidade com alta taxa de recidiva e agressividade local, apresentando também frequente associação com a Síndrome do Carcinoma Basocelular Neviode (SCBCN), por isso a patogêneses de este tumor tem sido intensamente estudada. A transformação e proliferação de células neoplásicas normalmente envolvem a desregulação de vias de sinalização que participam do desenvolvimento embrionário normal, principalmente a via Sonic Hedgehog (Shh). A expressão de certas proteínas presentes nesta via foi detectada em vários tumores odontogênicos, sugerindo que desempenha um papel importante nas interações epiteliais e na proliferação de células tumorais. Embora o papel da via de sinalização Shh não esteja bem estabelecida no desenvolvimento de TOQCs, sugere-se que sua ativação pode ser correlacionada com o comportamento clínico agressivo destas lesões. O objetivo deste estudo foi avaliar a expressão imunoistoquímica das proteínas da via de sinalização Shh em TOQCs esporádicos e associados a SCBCN, além de comparar a sua expressão entre lesões recorrentes e não recorrentes. Para isso foi realizado um estudo retrospectivo onde as características clinicopatológicas de 62 pacientes foram avaliadas, a expressão imunoistoquímica das proteínas Shh, Ptch1, Ptch2, Smo, Gli1, Gli2 e Gli3 foi analisada em todas as amostras, comparando TOQCs sindrômicos (29 lesões) e TOQCs esporádicos (57 lesões), assim como sua respectiva recorrência. Com este estudo foi possível observar que as proteínas Shh, Smo e Gli1 revelaram aumento da expressão em TOQCs associados a SCBCN, em comparação com tumores esporádicos. Shh mostrou expressão citoplasmática intermédia dentro da camada basal em tumores sindrômicos, Smo por sua vez revelou forte expressão nuclear e citoplasmática nas camada basal e suprabasal de tumores sindrômicos, enquanto que a expressão de Gli1 foi mais elevada apenas no citoplasma de TOQCs associados a síndrome em comparação com tumores esporádicos. No que diz respeito a sua recorrência, as proteínas Ptch1 e Gli2 mostraram maior expressão em TOQCs esporádicos e recorrentes, enquanto que a expressão Gli1 foi mais relevante nos tumores recorrentes e associados a SCBCN. Os nossos resultados sugerem que a maior expressão das proteínas Shh, Smo e Gli1 em TOQCs pode contribuir para o diagnóstico precoce de lesões associadas com a SCBCN. Da mesma forma, as proteínas Ptch1 e Gli2 pode predizer o risco de recorrência de TOQCs esporádicos, enquanto Gli1 sugere uma potencial associação de recorrência em tumores sindrômicos. / Keratocystic Odontogenic Tumor (KCOT) is considered an entity of high recurrence rates and local aggressiveness, also often presenting association with Nevoid basal cell carcinoma syndrome (NBCCS), and the pathogenesis of this tumor has been therefore intensively studied. The transformation and proliferation of neoplastic cells usually involve deregulation of signaling pathways participating in normal embryonic development, mainly via Sonic Hedgehog (Shh). The expression of certain proteins of this pathway has been detected in several odontogenic tumors, suggesting that plays an important role in epithelial interactions and proliferation of tumor cells. Although the role of Shh signaling pathway is not well established in the development of KCOTs it has been suggested that its activation can be correlated to the aggressive clinical behavior of these lesions. The aim of this study is therefore to evaluate the immunohistochemical expression of proteins of Shh signaling pathway in sporadic KCOTs and associated with NBCCS and to compare their expression between recurring and non-recurring lesions.thus, a retrospective study was performed where the clinicopathological features of 62 patients were evaluated, the immunohistochemical expression of the Shh, Ptch1, Ptch2, Smo, Gli1, Gli2 and Gli3 protein, was analyzed in all samples, comparing syndromic KCOTs ( 29 lesions) and sporadic KCOTs (57 lesions), and also their respective recurrence. The results showed that the expression of Shh, Smo and Gli1 proteins was increased in KCOTs associated with NBCCS compared to sporadic tumors. Shh showed intermediate cytoplasmic expression within the basal layer syndromic tumors, Smo in turn showed strong nuclear expression and cytoplasmic in basal and suprabasal layers of syndromic tumors, while Gli1 cytoplasm expression was higher only in KCOTs associated syndrome compared with sporadic tumors. Regarding recurrent tumors, Ptch1 and Gli2 proteins showed higher expression in sporadic and recurrent KCOTs, while Gli1 expression was more significant in recurrent tumors and associated NBCCS. Our results suggest that increased expression of Shh, Smo and Gli1 proteins in KCOTs can contribute to early diagnosis of KCOTs associated with the NBCCS. Likewise, Ptch1 and Gli2 proteins can predict the risk of recurrence of sporadic KCOTs, while Gli1 suggest a potential association to recurrence into syndromic tumors.

Introdução: Em crianças das regiões Sul e Sudeste do Brasil há uma incidência elevada de tumores adrenocorticais (TAC). Anormalidades da ?-catenina tem sido encontradas em TAC em adultos e sugerem a ativação da via Wnt/ -catenina nestes tumores. No entanto, não há estudos avaliando o papel desta via em casuísticas de TAC pediátricos. Objetivos: Avaliar o papel da via Wnt/catenina e mutações do gene CTNNB1 na tumorigênese adrenocortical pediátrica. Indivíduos, Material e Métodos: Foram avaliados 62 pacientes pediátricos com TAC oriundos de dois centros de referência. Controles: córtex adrenal de indivíduos jovens com morte acidental. Avaliou-se a presença de mutação nos genes TP53 e CTNNB1. A expressão de genes da via Wnt (CTNNB1, o ligante WNT4, os inibidores SFRP1, DKK3 e AXIN1, o fator de transcrição TCF7 e os genes-alvo MYC e WISP2) foi avaliada por qPCR, utilizando-se o método de 2-Ct. Adicionalmente, a expressão de proteínas da via Wnt/-catenina e P53 foi avaliada por imunoistoquímica. Avaliou-se a relação entre possíveis anormalidades moleculares com o fenótipo clínico e o desfecho. Resultados: A sobrevida geral foi maior em pacientes menores que 5 anos de idade (p<0.0001) e em pacientes com estágios tumorais menos avançados (p<0.0001). A mutação P53 p.R337H foi encontrada em 87% dos pacientes e não se associou com características clinicopatológicas ou desfecho. Mutações do gene CTNNB1 foram encontradas em 4/62 (6%) TAC, todos carreadores da mutação P53 p.R337H. Houve associação entre óbito e presença de mutações do gene CTNNB1 (p=0,02). Acúmulo difuso da -catenina foi observado em 71% dos TAC, a maioria sem mutações do CTNNB1. Comparados a adrenais normais, os TAC apresentaram aumento da expressão do RNAm de CTNNB1 (p=0.008) e diminuição da expressão de genes inibidores da via Wnt: DKK3 (p<0.0001), SFRP1 (p=0.05) e AXIN1 (p=0.04). Com relação aos genes-alvo da via Wnt/-catenina, TAC apresentaram expressão aumentada de WISP2 e baixa expressão de MYC. Maior sobrevida geral foi associada à expressão baixa de SFRP1 (p=0.01), WNT4 (p=0.004) e TCF7 (p<0.01). Conclusões: Em TAC pediátricos, mutações somáticas ativadoras do gene CTNNB1 são pouco freqüentes e parecem estar associadas à maior ocorrência de óbito. Mesmo na ausência de mutações do gene CTNNB1, estes tumores apresentaram acúmulo de -catenina e do gene-alvo WISP2 e expressão reduzida de inibidores da via Wnt (DKK3, SFRP1 e AXIN1). Estes dados demonstram evidências de anormalidades na via Wnt/-catenina em TAC pediátricos, mesmo na ausência de mutações do gene CTNNB1. É provável que outros eventos genéticos afetando a via Wnt/-catenina estejam envolvidos na tumorigênese adrenocortical pediátrica / Context: CTNNB1 mutations and activation of Wnt/-catenin pathway are frequent in adult adrenocortical tumors (ACTs) but data on childhood ACTs are lacking. Objective: To investigate Wnt/-catenin pathway abnormalities and CTNNB1 mutations in childhood ACTs. Patients and Methods: Clinicopathological findings and outcome of 62 childhood ACTs patients were analyzed regarding to CTNNB1/ -catenin mutations and to the expression of Wnt-related genes (CTNNB1, a Wnt ligand: WNT4, Wnt inhibitors: SFRP1, DKK3 and AXIN1, a transcription factor: TCF7, and target genes: MYC and WISP2) by qPCR and immunohistochemistry. Results: Overall survival (OS) was higher in patients younger than 5 years (p<0.0001) and associated with less advanced tumoral stage (p<0.0001). The p.R337H P53 mutation, found in 87% of the patients, was not associated with clinicopathological findings or outcome. CTNNB1 activating mutations were found in only 4/62 ACTs (6%), all of them harboring TP53 mutation. There was association between the presence of CTNNB1 mutation and death (p=0.02). Diffuse -catenin accumulation was found in 71% of ACTs, most of them without CTNNB1 mutation. CTNNB1 mutated ACTs presented weak/moderate -catenin accumulation. Compared to normal adrenals, ACTs presented increased expression of CTNNB1 (p=0.008) and underexpression of Wnt inhibitor genes: DKK3 (p<0.0001), SFRP1 (p=0.05) and AXIN1 (p=0.04). With regards to Wnt/-catenin target genes, ACTs presented lower expression of MYC but increased expression of WISP2. Higher overall survival was associated with underexpression of SFRP1 (p=0.01), WNT4 (p=0.004) and TCF7 (p<0.01). Conclusions: In childhood ACTs, CTNNB1 mutations are rare and appear to be associated with poor prognosis. Regardless of CTNNB1 mutations, these tumors presented reduced expression of Wnt inhibitor genes (DKK3, SFRP1 and AXIN1) and increased expression of CTNNB1 and a target gene, WISP2. Thus, besides CTNNB1 mutations, additional genetic events affecting the Wnt/-catenin pathway may be involved in childhood adrenocortical tumorigenesis.

O Tumor Odontogênico Queratocístico (TOQC) é considerado uma entidade com alta taxa de recidiva e agressividade local, apresentando também frequente associação com a Síndrome do Carcinoma Basocelular Neviode (SCBCN), por isso a patogêneses de este tumor tem sido intensamente estudada. A transformação e proliferação de células neoplásicas normalmente envolvem a desregulação de vias de sinalização que participam do desenvolvimento embrionário normal, principalmente a via Sonic Hedgehog (Shh). A expressão de certas proteínas presentes nesta via foi detectada em vários tumores odontogênicos, sugerindo que desempenha um papel importante nas interações epiteliais e na proliferação de células tumorais. Embora o papel da via de sinalização Shh não esteja bem estabelecida no desenvolvimento de TOQCs, sugere-se que sua ativação pode ser correlacionada com o comportamento clínico agressivo destas lesões. O objetivo deste estudo foi avaliar a expressão imunoistoquímica das proteínas da via de sinalização Shh em TOQCs esporádicos e associados a SCBCN, além de comparar a sua expressão entre lesões recorrentes e não recorrentes. Para isso foi realizado um estudo retrospectivo onde as características clinicopatológicas de 62 pacientes foram avaliadas, a expressão imunoistoquímica das proteínas Shh, Ptch1, Ptch2, Smo, Gli1, Gli2 e Gli3 foi analisada em todas as amostras, comparando TOQCs sindrômicos (29 lesões) e TOQCs esporádicos (57 lesões), assim como sua respectiva recorrência. Com este estudo foi possível observar que as proteínas Shh, Smo e Gli1 revelaram aumento da expressão em TOQCs associados a SCBCN, em comparação com tumores esporádicos. Shh mostrou expressão citoplasmática intermédia dentro da camada basal em tumores sindrômicos, Smo por sua vez revelou forte expressão nuclear e citoplasmática nas camada basal e suprabasal de tumores sindrômicos, enquanto que a expressão de Gli1 foi mais elevada apenas no citoplasma de TOQCs associados a síndrome em comparação com tumores esporádicos. No que diz respeito a sua recorrência, as proteínas Ptch1 e Gli2 mostraram maior expressão em TOQCs esporádicos e recorrentes, enquanto que a expressão Gli1 foi mais relevante nos tumores recorrentes e associados a SCBCN. Os nossos resultados sugerem que a maior expressão das proteínas Shh, Smo e Gli1 em TOQCs pode contribuir para o diagnóstico precoce de lesões associadas com a SCBCN. Da mesma forma, as proteínas Ptch1 e Gli2 pode predizer o risco de recorrência de TOQCs esporádicos, enquanto Gli1 sugere uma potencial associação de recorrência em tumores sindrômicos. / Keratocystic Odontogenic Tumor (KCOT) is considered an entity of high recurrence rates and local aggressiveness, also often presenting association with Nevoid basal cell carcinoma syndrome (NBCCS), and the pathogenesis of this tumor has been therefore intensively studied. The transformation and proliferation of neoplastic cells usually involve deregulation of signaling pathways participating in normal embryonic development, mainly via Sonic Hedgehog (Shh). The expression of certain proteins of this pathway has been detected in several odontogenic tumors, suggesting that plays an important role in epithelial interactions and proliferation of tumor cells. Although the role of Shh signaling pathway is not well established in the development of KCOTs it has been suggested that its activation can be correlated to the aggressive clinical behavior of these lesions. The aim of this study is therefore to evaluate the immunohistochemical expression of proteins of Shh signaling pathway in sporadic KCOTs and associated with NBCCS and to compare their expression between recurring and non-recurring lesions.thus, a retrospective study was performed where the clinicopathological features of 62 patients were evaluated, the immunohistochemical expression of the Shh, Ptch1, Ptch2, Smo, Gli1, Gli2 and Gli3 protein, was analyzed in all samples, comparing syndromic KCOTs ( 29 lesions) and sporadic KCOTs (57 lesions), and also their respective recurrence. The results showed that the expression of Shh, Smo and Gli1 proteins was increased in KCOTs associated with NBCCS compared to sporadic tumors. Shh showed intermediate cytoplasmic expression within the basal layer syndromic tumors, Smo in turn showed strong nuclear expression and cytoplasmic in basal and suprabasal layers of syndromic tumors, while Gli1 cytoplasm expression was higher only in KCOTs associated syndrome compared with sporadic tumors. Regarding recurrent tumors, Ptch1 and Gli2 proteins showed higher expression in sporadic and recurrent KCOTs, while Gli1 expression was more significant in recurrent tumors and associated NBCCS. Our results suggest that increased expression of Shh, Smo and Gli1 proteins in KCOTs can contribute to early diagnosis of KCOTs associated with the NBCCS. Likewise, Ptch1 and Gli2 proteins can predict the risk of recurrence of sporadic KCOTs, while Gli1 suggest a potential association to recurrence into syndromic tumors.

O carcinoma de cabeça e pescoço é uma neoplasia maligna de origem epitelial que resulta em aproximadamente 500.000 novos casos por ano ao redor do mundo. Diversos estudos têm sido conduzidos de maneira a elucidar os mecanismos de proliferação e invasão desta doença, sendo a via de sinalização Akt/mTOR e proteínas relacionadas, apontada como uma das principais vias envolvidas em sua progressão. Sabe-se que células neoplásicas, bem como células de diferentes tecidos, podem ter seu comportamento modificado após terem sido irradiadas com laser em baixa intensidade (LLLT). Porém, os mecanismos de atuação da luz laser de baixa potência sobre estas células permanecem ainda não completamente esclarecidos. Portanto, o objetivo deste estudo foi o de analisar a viabilidade celular e expressão das proteínas Akt, pAkt, Hsp90, S6, pS6 e Ciclina D1 em duas linhagens celulares de carcinoma de boca (SCC9 e SCC25), bem como em uma linhagem de queratinócitos orais humanos com displasia (DOK) após irradiação com laser em baixa intensidade. O laser utilizado foi um diodo semicondutor de arseneto de Gálio e Alumínio (GaAlAs) operando nos comprimentos de onda vermelho (660nm) e infravermelho (780nm), com potência fixa em 40mW e três densidades de energia para cada comprimento de onda disponível: 2.05J/cm², 3.07J/cm² e 6.15J/cm². A análise de apoptose foi realizada por meio do teste de TUNEL e a expressão proteica foi obtida com imunofluorescência e western blotting. Após análise estatística por meio do método ANOVA dois critérios e testes de Tukey ou teste T de estudante, todos com nível de significância de 5%, pôde-se concluir que a LLLT induziu comportamentos distintos em cada uma das linhagens celulares utilizadas. Foi notado aumento, bem como diminuição da viabilidade celular, dependendo do comprimento de onda utilizado e das células irradiadas. A densidade de energia de 2.05J/cm² foi a que produziu efeitos mais significativos em SCC9. Para a linhagem celular SCC25, a dose mais relevante foi a de 3.07J/cm², enquanto que para a linhagem DOK, a dose de 6.15J/cm² causou efeitos mais proeminentes. Estas respectivas doses foram escolhidas para cada uma das linhagens para dar continuidade aos experimentos de Western Blotting e Imunofluorescência. Dentre os resultados mais relevantes obtidos com estas técnicas, pode-se citar a variação dos níveis de pS6 e Ciclina D1 para a linhagem DOK em determinados períodos. Já a linhagem SCC9 apresentou variação dos níveis de pAkt e Ciclina D1 nos períodos estudados. A linhagem SCC25 também teve as expressões de pAkt, pS6 e Ciclina D1 modificadas por LLLT. De maneira interessante, o aparecimento ou manutenção de uma isoforma de Hsp90 foi encontrado em SCC9 e SCC25 após irradiação laser. Por fim, a indução de apoptose foi detectada na linhagem SCC25. Em conclusão, pode-se dizer que a LLLT, como empregada neste estudo, foi capaz de aumentar a expressão de proteínas relacionadas à progressão e invasão em todas as linhagens estudadas. Além disso, a irradiação laser foi única, apesar de ter causado efeitos prolongados, algumas vezes até o último período estudado. / Head and neck squamous cell carcinoma (HNSCC) is an epithelial malignant neoplasm that accounts for approximately 500.000 new cases yearly around the world. Several studies have been conducted to elucidate the mechanisms of proliferation and invasion of this lesion, whereas the Akt/mTOR signaling pathway with its related proteins is being pointed out as one of the main pathways involved in HNSCC`s progression. Neoplastic cells, as well as cells that originate from different tissues may have their behavior modified by low level laser therapy (LLLT); however, the mechanisms through which the low level laser light interacts with these cells remain poorly understood. Thus, this study sought to evaluate the cell viability and the expression levels of Akt, pAkt, Hsp90, S6, pS6 and Cyclin D1 proteins in two oral squamous cell carcinoma cell lineages (SCC9 and SCC25) and in one oral dysplastic human keratinocyte cell line (DOK) after they had been treated with LLLT. The laser device was a semiconductor diode of Gallium and Aluminum Arsenate (GaAlAs), operating with wavelengths of 660nm (red) and 780nm (infrared), with a fixed power of 40mW and giving three different energy densities: 2.05J/cm², 3.07J/cm² and 6.15J/cm². Apoptosis was analyzed through TUNEL test and the protein expression was accessed with Immunofluorescence and Western blotting. After statistical analysis through two-way ANOVA and Tukey or Student`s T test, all of them with a level of significance of 5%, it was concluded that LLLT induced distinct behaviors to each of the studied cell lines. Increases and inhibitions in cell viabilities were detected depending on the wavelength and also on the irradiated cell line. The energy density of 2.05J/cm² produced the most significant findings over SCC9. On the other hand, in SCC25 the most relevant results were detected with 3.07J/cm², while the most prominent findings were seen with 6.15J/cm² when the cell line DOK was evaluated. In that way, these respective doses were chosen for each cell line to continue with Western blotting and Immunofluorescence. Among the most relevant findings, the variation of pS6 and Cyclin D1 levels can be cited for DOK in some evaluated periods. SCC9 presented both pAkt and Cyclin D1 variations in the studied periods. Besides that, SCC25 also had pAkt, pS6 and Cyclin D1 levels modified by LLLT. Interestingly, the appearance and maintenance of an Hsp90 isoform was found in SCC9 and SCC25 after laser irradiation. Moreover, the induction of apoptosis was detected for the SCC25 cell line. Finally, the LLLT employed herein was able to enhance the expression of proteins related to progression and invasion in all of the studied cell lines. In addition, there was a single laser irradiation, although it caused prolonged effects, sometimes through the latest evaluated period.

Introdução: Baixas concentrações séricas de esclerostina foram descritas em pacientes com Espondilite Anquilosante (EA). No entanto, não existem dados sobre a importância deste inibidor da via de sinalização Wnt em pacientes com EA durante o tratamento com anti fator de necrose tumoral alfa (TNFa). Objetivos: Avaliar longitudinalmente os níveis séricos de esclerostina e sua associação com inflamação e densidade mineral óssea (DMO) em pacientes com EA em tratamento com anti-TNFa. Métodos: Trinta pacientes com EA em atividade foram avaliados no início, 6 e 12 meses, após terapia anti-TNFa em relação aos parâmetros clínicos (BASDAI, BASFI, BASMI e ASQoL), marcadores inflamatórios e dano radiológico basal (mSASSS). Trinta indivíduos saudáveis pareados por idade e sexo constituíram o grupo controle. As análises laboratoriais de esclerostina e da ligação de esclerostina ao receptor LRP6 e a DMO foram realizadas nos pacientes nos mesmos períodos de avaliação e comparadas aos controles. Resultados: Na avaliação inicial, pacientes com EA apresentavam menores concentrações séricas de esclerostina [60,5 (32,7) vs. 96,7 (52,9) pmol/l,P=0,002] e níveis similares de ligação de esclerostina ao receptor LRP6 (P=0,387) em relação aos controles. Foi observado melhora do BASDAI, BASFI, BASMI, ASQoL comparando tempo basal vs. 6 vs. 12 meses (P<0,01). Concomitantemente, observou-se um aumento gradual da DMO da coluna lombar (P<0,001) e no início do estudo os pacientes apresentavam uma correlação positiva entre avaliação radiológica basal (mSASSS) e a DMO da coluna lombar (r=0,468, P<0,01). Foi observada também uma redução dos marcadores inflamatórios comparando tempo basal vs. 6 vs. 12 meses (P<0,01). Os níveis de esclerostina aumentaram progressivamente após o tratamento com anti-TNFa [60,5 (32,7) vs. 67,1 (31,9) vs. 72,7 (32,3) pmol/l, P<0,001]. Entretanto, após 12 meses de terapia anti-TNFa as concentrações séricas de esclerostina permaneceram significativamente mais baixos em relação os controles [72,7 (32,3) vs. 96,7 (52,9) pmol/l, P=0,038]. Além disso, aos 12 meses, os níveis séricos de esclerostina ficaram mais baixos nos 10 pacientes que ainda apresentavam proteína C reativa elevada (PCR=5mg/l), comparados aos pacientes que apresentaram normalização dos níveis de PCR (P=0,004). Interessantemente, estes 10 pacientes com inflamação persistente já apresentavam concentrações séricas mais baixas de esclerostina quando comparados aos demais pacientes (P=0,023) antes do tratamento com anti- TNFa. A análise de regressão logística demonstrou que os pacientes com EA com níveis baixos de esclerostina apresentam um risco aumentado de apresentar PCR alta após 12 meses de tratamento (odds ratio = 7,43, 95% IC 1,23-45,01, P=0,020) quando comparados aos pacientes com níveis altos de esclerostina no tempo basal. Conclusão: Concentrações persistentemente baixas de esclerostina estão associados a inflamação contínua em pacientes com EA tratados com terapia anti-TNFa. / Introduction: Sclerostin levels have been reported to be low in ankylosing spondylitis (AS), but there is no data regarding the possible role of this Wnt inhibitor during anti tumor necrosis factor alpha (TNFa) therapy. Objectives: The present study longitudinally evaluated sclerostin levels, inflammatory markers and bone mineral density (BMD) in AS patients under anti-TNFa therapy. Methods: Thirty active AS patients were assessed at baseline, 6 and 12 months after anti-TNFa therapy regarding clinical parameters (BASDAI, BASFI, BASMI and ASQoL), inflammatory markers, BMD and baseline radiographic damage (mSASSS). Thirty age- and sex-matched healthy individuals comprised the control group. Patients\' sclerostin levels, sclerostin binding LRP6 and BMD were evaluated at the same time points and compared to controls. Results: At baseline, AS patients had lower sclerostin levels [60.5 (32.7) vs. 96.7 (52.9) pmol/l, P=0.002] and comparable sclerostin binding to LRP6 (P=0.387) than controls. Improvement of BASDAI, BASFI, BASMI, ASQoL was observed at baseline vs. 6 vs. 12 months (P<0.01). Concomitantly, a gradual increase in spine BMD (P<0.001) and a positive correlation between baseline mSASSS and spine BMD was found (r=0.468, P<0.01). Inflammatory parameters reduction was observed comparing baseline vs. 6 vs. 12 months (P<0.01). Sclerostin levels progressively increased [60.5 (32.7) vs. 67.1 (31.9) vs. 72.7 (32.3) pmol/l, P<0.001] after anti-TNFa treatment. At 12 months, the sclerostin levels remained significantly lower in patients compared to controls [72.7 (32.3) vs. 96.70 (52.85) pmol/l, P=0.038]. Moreover, sclerostin serum levels at 12 months were lower in the 10 patients with high CRP (=5mg/l) compared to the other 20 patients with normal CRP (P=0.004). Of note, these 10 patients with persistent inflammation also had lower sclerostin serum levels at baseline compared to the other patients (P=0.023). Univariate logistic regression analysis demonstrated that AS patients with lower sclerostin serum levels had an increased risk to have high CRP at 12 months (odds ratio=7.43, 95% CI 1.23-45.01, P=0.020) than those with higher sclerostin values. Conclusion: Persistent low sclerostin levels may underlie continuous inflammation in AS patients under anti-TNFa therapy.

Les leucémies aigües lymphobastiques (LAL) représentent un tiers des leucémies et constituent le cancer pédiatrique le plus fréquent chez l’enfant. Les LAL de type T (LAL-T)sont caractérisées par l’expansion anormale de progéniteurs de lymphocytes T. Aujourd’hui,la réponse curative aux traitements est proche de 80% chez l’enfant et 50% chez l’adulte. La rechute reste donc fréquente et souvent de mauvais pronostic. Pour ces raisons,l’identification de nouvelles voies de signalisation en vue de développer de nouvelles stratégies thérapeutiques est cruciale afin d’améliorer le traitement des LAL-T.Les résultats précédents du laboratoire ont révélé l’activation soutenue de la voie calcineurine (Cn)/NFAT dans des échantillons humains de lymphomes et de LAL, ainsi que dans des modèles murins de ces pathologies. Le laboratoire a ensuite montré que Cn est intrinsèquement requise pour la capacité des cellules leucémiques de LAL-T à propager la maladie (activité LIC « Leukemia Initiating Cells ») dans un modèle murin de LAL-T induit parun allèle activé de NOTCH1 (ICN1). Puisque l’inhibition pharmacologique de Cn induit de nombreux effets secondaires, la recherche de cibles thérapeutiques en aval de Cn constitue un axe de recherche important. J’ai participé à une étude du laboratoire montrant que l’expression à la surface cellulaire de CXCR4 est régulée par Cn et requise pour la migration des cellules de LAL-T, mais non suffisante pour rétablir le potentiel de ré-initiation suggérant que d’autres effecteurs doivent être impliqués dans cette activité.Les facteurs de transcription NFAT (NFAT1, NFAT2 et NFAT4) sont des effecteurs importants de Cn en réponse à la signalisation calcique lors du développement des thymocytes, mais également dans les lymphocytes T. L’essentiel de ce travail de thèse a utilisé des LAL-T induites par ICN1 dans lesquelles l’inactivation génique des trois facteurs NFAT par recombinaison homologue. Nous avons ainsi montré que (i) les facteurs NFAT sont requis en aval de Cn pour le potentiel LIC des LAL-T-ICN1 in vivo, (ii) leur inactivation altère la survie, la prolifération et la migration des cellules de LAL-T in vitro, (iii) NFAT1,NFAT2 et NFAT4 ont une fonction largement redondante dans les LAL-T. Nous avons également par une approche transcriptomique identifié deux gènes dont l’expression estsous contrôle des facteurs NFAT et impliqués dans la régulation de la survie et de la prolifération des LAL-T in vitro : CDKN1A et MAFB.Tout comme la voie Cn/NFAT, les CaMKs sont des protéines kinases activées en aval de la signalisation calcique dans les lymphocytes T. Nous avons montré par une approche pharmacologique que l’inhibition des CaMKs dans les LAL-T-ICN1 in vitro altère la survie etla prolifération des cellules leucémiques. L’inhibition spécifique par une approche d’ARN interférence de deux isoenzymes CaMKIIγ et CaMKIIδ suggèrent que ces protéines jouent dans le maintien des cellules leucémiques in vitro. / T cell acute lymphoblastic leukemia (T-ALL) is an aggressive malignancy of T cell progenitors. Despite initial response to chemotherapy, relapses remain frequent in children and adults. Previous results identify sustained activation of Calcineurin (Cn)/NFAT signaling pathway in human T-ALL and murine T-ALL models. Importantly, they also demonstrated Cn is essential for T-ALL Leukemia Initiating Cells (LIC) activity in a murine model of T-ALL induced by an activated allele of NOTCH1 (ICN1). Since pharmacologic inhibition of Cn induces side effects, we aim to identify downstream effectors involved in T-ALL. NFAT (Nuclear Factor of Activated T cells) factors play crucial roles downstream Cn during development and activation of T cells. To address their role in T-ALL, we generated mouse ICN1-induced T-ALL in which NFAT genes can be inactivated either single or in combination following Cre-mediated gene deletion. We demonstrated that (i) NFAT factors are required downstream Cn for LIC activity in T-ALL in vivo (ii) ex vivo NFAT factors deletion alters survival, proliferation and migration of T-ALL (iii) NFAT1, 2 and 4 have a largely redundant function in T-ALL. Moreover, the NFAT-dependant transcriptome allowed to identify important targets (CDKN1A, MAFB) involved in T-ALL survival and proliferation in vitro. Calmodulin-dependant kinases (CaMK) are kinases activated by calcium signaling in T cells. We showed that pharmacologic inhibition of CaMKs in ICN1-induced T-ALL alters survival and proliferation of T-ALL in vitro. Beside, specific inhibition by RNA interference of CaMKIIg and CaMKIId suggests a putative role of these kinases in T-ALL maintenance.

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L’infection chronique par le virus de l’hépatite C (VHC) conduit au développement de pathologies hépatiques, telles que la fibrose dont le terme évolutif est la cirrhose sur laquelle peut se développer un carcinome hépatocellulaire. Les observations cliniques indiquent que le VHC interfère avec la voie de signalisation du Transforming Growth Factor β (TGFβ). Entre autres fonctions, cette cytokine induit la transition épithélio-mésenchymateuse (EMT), ce qui favorise la migration cellulaire et l'invasion tumorale. Le but de cette thèse est d'analyser l'impact des protéines non structurales du VHC sur la voie de signalisation du TGFβ.Nous avons montré que le réplicon subgénomique du VHC induit une augmentation de la signalisation du TGFβ résultant en une plus forte expression de gènes associés à l’EMT et induisant un phénotype d’EMT. L’expression de la protéase virale NS3-4A seule, augmente et prolonge la phosphorylation de Smad2/3 en aval du récepteur du TGFβ et renforce l’expression de certains gènes cibles du TGFβ. L’analyse des interactions entre les protéines du VHC et les protéines de la voie du TGFβ a permis d’identifier l’interaction entre NS3-4A et la protéine Smurf2. Le réplicon subgénomique ou la protéase NS3-4A ont des rôles antagonistes à la protéine Smurf2 sur la voie de signalisation du TGFβ. L’analyse globale des gènes régulés par le TGFβ dans les cellules exprimant le réplicon subgénomique a permis d’identifier, que dans ces cellules, le TGFβ induit une réponse pro-tumorale.Ces résultats montrent que NS3-4A induit une plus forte réponse des cellules au TGFβ, en inhibant la fonction de Smurf2 dans le rétrocontrôle négatif de la voie du TGFβ. Ce nouveau mécanisme d’interférence du VHC avec la voie du TGFβ pourrait contribuer à l’EMT des cellules hépatocytaires infectées favorisant ainsi la cancérisation. Ce travail apporte de nouvelles pistes dans la compréhension des mécanismes associés à la cancérisation chez les patients chroniquement infectés par le VHC. / Chronic infection by hepatitis C virus (HCV) leads to the development of hepatic diseases like fibrosis which evolves into cirrhosis on which can develop hepatocellular carcinoma. Clinical observations indicate that HCV interferes with the TGFβ signaling pathway. Among other functions this cytokine induces epithelial-to-mesenchymal transition (EMT) promoting cell migration and tumor invasion. The aim of this study is to analyze the impact of HCV non structural proteins on TGFβ signaling pathway. We have demonstrated that the HCV subgenomic replicon induces an enhancement of the TGFβ signaling pathway resulting in a strong expression of EMT associated genes and inducing EMT phenotype. The expression of the NS3-4A viral protein alone enhances and stabilizes Smad2/3 phosphorylation downstream TGFβ receptor and increases the expression of some TGFβ target genes. The analysis of interactions between HCV proteins and proteins of the TGFβ signaling pathway has shown the interaction of NS3-4A with Smurf2 protein. HCV subgenomic replicon and NS3-4A have antagonistic roles to Smurf2 on TGFβ signaling pathway. The global analysis of genes regulated by TGFβ in cells expressing HCV subgenomic replicon indicates that in these cells TGFβ induces a pro-tumor answer.These results show that NS3-4A enhances TGFβ answer by inhibiting Smurf2 functions in the negative feedback loop of the TGFβ pathway. This new mechanism of HCV interference with the TGFβ pathway can contribute to EMT in infected hepatocytes thus promoting carcinogenesis. This work provides new leads to understand the mechanisms associated to carcinogenesis in HCV chronically infected patients.