Protein kinases ERK1 and ERK2 are one of the most studied proteins in cell signalling. Both proteins are involved in a plethora of processes, such as phosphorylation and activation of kinases as part of signalling pathways. Enzymes ERK1 and ERK2 are part of MAPK/ERK signalling cascade, connected to many cellular including cell proliferation, cell growth or differentiation. The MAPK/ERK signalling cascade is often activated in different types of tumors, making it a candidate for developing new chemical inhibitors. One of the important questions in fundamental research of ERK1 and ERK2 protein kinases is the search for difference between these proteins. Current knowledge points to redundancy of both proteins, howver several examples suggest otherwise. Recently, the work presented in Casanova et al. 2012 indirectly suggests divergent effect of ERK1 and ERK2 on cap-independent translation initiation. In the Laboratory of RNA biochemistry we focus on HCV IRES (Hepatitis C Virus Internal Ribosome Entry Site) dependent translation initiation. This diploma thesis lead to establish RNA interference method in our laboratory and to establish reporter system to study ERK1 and ERK2 effect on HCV IRES dependent translation initiation. Based on our data acquired during our research, we present in this work...

Comme pour la plupart des virus à ARN+, le VHC induit des remaniements membranaires appelés membranous web. Les protéines non structurales virales formant le complexe de réplication du virus sont associées à ces membranes néosynthétisées. La compréhension de la mise en place de ces membranes cellulaire est encore actuellement mal connue. Afin d’étudier ce phénomène, nous avons dans un premier temps sélectionné des clones cellulaires Huh7.5 hébergeants un réplicon sous-génomiquedu virus. Nous avons ainsi pu mettre en évidence la présence d’un réseau multivésiculaire semblant provenir de l’induction de mécanismes d’autophagie. Plus récemment l’utilisation du modèle de propagation du virus complet nous a permis de mieux caractériser ce réseau multivésiculaire en déterminant trois sous réseaux vésiculaires structuralement différents. L’analyse de cette étude est effectuée principalement par microscopie électronique avec des techniques innovantes tels que la reconstruction tridimensionnelle et des immunogolds. / As other RNA viruses, HCV induces membrane alterations termed membranous web and its nonstructural proteins forming the viral replication complex are associated to these neo-synthesized membranes. The mechanism underlying these host cell membranes alterations is still currently unknown. To investigate this mechanism, we initially selected Huh7.5 cells clones harbouring a HCV subgenomic replicon. We were able to demonstrate the presence of a multivesicular network apparently linked to the autophagy induction mechanisms. More recently, using the cell culture-adapted HCVsystem, we better characterized this network by determining three multivesiculars vesicles structurally different subnets. This study was carried out mainly by performing electron microscopy observations,with using innovative techniques such as three-dimensional reconstruction and immunogold.

Le carcinome hépatocellulaire (HCC) est une tumeur de mauvais pronostic caractérisée, comme la plupart de cancers, par l'association paradoxale de télomères courts et d'une importante activité télomérase. Cette attrition télomérique joue un rôle central dans l'instabilité chromosomique à l'origine de la promotion et de l'évolution tumorale. Les premières causes d'HCC correspondent aux infections chroniques par les virus hépatotropes : virus de l'hépatite B (VHB) et virus de l'hépatite C (VHC). Dans une première étape nous avons disséqué les dérégulations télomériques dans les HCC et les cirrhoses liées au VHB, VHC ou encore à l'alcool. Nous avons observé que ces dérégulations sont acquises tôt, au stade prétumoral, et persistent au stade tumoral. Ces dérégulations sont spécifiques d'un carcinogène donné. Aux stades tardifs et tumoraux de l'infection par le VHB, les cellules hépatiques expriment fréquemment une protéine tronquée en partie C-terminale d'HBx ainsi que des formes réarrangées du gène PreS/S telle que PreS2. Dans une seconde étape nous avons trouvé qu'à l'opposé de la forme sauvage, HBx tronquée réprime hTERT, diminue l'activité télomérase, raccourcit les télomères, augmente la proportion de ponts anaphasiques et déclenche la sénescence de cellules primaires. Sachant qu'au stade tumoral les cellules transformées ré-expriment hTERT nous avons testé l'effet d'une coexpression de PreS2 et d'HBx tronquée et avons pu montrer que PreS2 contrecarrait l'effet répresseur d'HBx sur hTERT. Néanmoins de façon étonnante, PreS2 ne parvenait pas à rallonger les télomères en présence d'HBx tronquée. Les facteurs protégeant les télomères coopèrent avec la télomérase pour l'élongation et plusieurs de ces protéines sont par ailleurs impliquées dans la réparation des dommages à l'ADN. Nous avons trouvé qu'HBx tronquée modifiait spécifiquement l'expression de la plupart des protéines du télosome selon un patron connu pour inhiber l'effet de la télomérase. Nous avons montré que des dommages à l'ADN télomérique liés à l'incubation de cellules primaires avec la néocarcinostatine inhibaient l'élongation des télomères par hTERT. Ayant trouvé que PreS2 et HBx tronquée induisaient des dommages à l'ADN, nous proposons que cet effet explique l'impossibilité pour PreS2 d'allonger les télomères de cellules exprimant HBx tronquée / Among the numerous genetic defects that underly with hepatocarcinogenesis, telomere abnormalities seem to play a role both in tumor promotion and maintenance. Telomeres, the chromosome extremities, are protected by specific proteins, the Shelterin complex and by additional factors. Besides telomerase dysregulation, changes in the expression of these telomere factors have been observed in cancers. Herewe first tested the hypothesis that such dysregulations might occur in HCC with patterns depending onthe cause of HCC. For HBV-, HCV- and alcool-dependant HCC we found that telomeric dysregulations appear to be carcinogen-specific and occur early during the course of the disease and are persistent in the tumor. At the late stage of HBV-dependent disease and corresponding tumors, hepatocytes produce 3’ deleted mutants of HBx (3’DM HBx) but also a rearranged form of the PreS/S gene: PreS2. We then found that, unlike WT HBx, 3’ DM HBx repress hTERT transcription, decrease telomerase activity, shorten telomere length, increase anaphase bridges and trigger senescence in transfected primary cells. It’s well known that hTERT it re-expressed in tumors, so we tested PreS2 and 3’DM HBx transfection. We show that PreS2 counteracts 3’DM HBx effect on hTERT transcription and telomerase activity. However surprisingly PreS2 wasn’t able to elongate telomeres in 3’DM HBx expressing cells. Telomeric factors interact with telomerase allowing telomere elongation. Moreover many of these factors are implicated in DNA damage repair systems. We found that all Shelterin’s and some other telomeric factors’s expression in dyregulated in 3’DM HBx expressing cells. Moreover we show that neocarcinostatin dependent DNA damage in MRC5 primary cell prevent hTERT-based telomere elongation. Also finding that PreS2 and 3’DM induce DNA damage, we suggest that 3’DM HBx prevents PreS2 and hTERT- based telomere elongation

O objetivo deste trabalho foi avaliar a infecção pelo vírus da hepatite C (HCV) em indivíduos de Londrina e regiões circunvizinhas. Amostras de doadores de sangue e de indivíduos infectados pelo vírus da imunodeficiência humana (HIV) foram analisadas pela metodologia de enzimaimunoensaio de micropartículas (MEIA), obtendo-se a freqüência de positividade para anticorpos anti-HCV de 0,8% e de 20,2%, respectivamente. Um conjunto de 185 amostras soropositivas para anti-HCV pelo MEIA foi submetido a outros testes laboratoriais, para avaliação da correlação entre os diferentes métodos empregados. Apenas 79% destas amostras apresentaram resultado reagente em um segundo teste imunoenzimático (ELISA) empregado, sendo que a maior proporção de resultados discordantes ocorreu entre doadores de sangue. O mesmo ocorreu na pesquisa do RNA viral, onde 111 (67%) das 166 amostras analisadas apresentaram resultado positivo, sendo que a positividade foi maior entre indivíduos HIV soropositivos e pacientes com hepatite crônica do que entre os doadores de sangue. Quinze amostras foram submetidas ao immunoblot (IB), tendo-se obtido resultados positivos neste teste apenas nas amostras reagentes nos dois métodos imunoenzimáticos utilizados. Também pudemos verificar um grande número de amostras com resultado indeterminado no IB, inclusive entre amostras que eram negativas no segundo teste sorológico. Embora a amostragem fosse pequena, com apenas 61 amostras analisadas, a genotipagem do HCV revelou que os genótipos circulantes em nossa região são o tipo 1 (77,1%), seguido do tipo 3 (21,3%) e o tipo 2 (1,6%). Finalmente, avaliamos alguns fatores de risco associados à infecção pelo HCV, sendo que o principal fator de risco encontrado em indivíduos co-infectados pelo HIV/HCV foi o uso de drogas injetáveis, e em indivíduos sem infecção pelo HIV foi a transfusão sangüínea. O presente estudo contribuiu para a avaliação do perfil da infecção pelo HCV em indivíduos da nossa população, permitindo inclusive verificar a distribuição dos genótipos do HCV nesta região. / The objective of this work was to evaluate hepatitis C virus (HCV) infection in individuals of Londrina, Paraná State, Brazil, and adjacent areas. Samples of blood donors and individuals infected with Human Immunodeficiency virus (HIV) were analyzed by microparticle enzyme immunoassay (MEIA). Anti-HCV antibody frequency was 0.8% in blood donors, and 20.2% in HIV patients. A group of 185 anti-HCV positive samples by MEIA was submitted to other laboratorial tests, in order to access the correlation among different methods used. Only 79% of samples were reactive by a second antibody-screening test (enzime-linked immunosorbent assay - ELISA), and a great proportion of discordant results was verified among blood donors. The same happened at HCV-RNA detection by polymerase chain reaction (PCR), where 111/166 (67%) of samples showed positive results, which was greater among HIV positive individuals and patients with chronic hepatitis than among blood donors. Only 15 samples were submitted to immunoblot (IB): positive results were obtained only at samples which were also reactive by the two antibody-screening tests used. We could also verify a great number of anti-HCV indeterminate results by IB, which also happened among samples tested negative by the second serologic assay. Although the small number of samples used in genotype determination of HCV, only 61, our data revealed that the circulating genotypes in our region are type 1 (77.1%), followed by type 3 (21.3%) and type 2 (1.6%). Finally, we evaluated some risk factors associated to HCV infection, and we found that intravenous drug use was the most common risk factor among patients HIV/HCV co-infected, while blood transfusion was the most important risk factor in the group without HIV infection. The present study contributed to the evaluation of HCV infection in our population, so that the distribution of HCV genotypes in the region could be accessed.

Introdução: A infecção pelo VHC é uma epidemia de proporções globais, que se torna crônica em cerca de 85% dos indivíduos. Sobrecarga de ferro secundária a mutações HFE vem sendo proposta como fator agravante na evolução da hepatite crônica C. Objetivos: Avaliar se sobrecarga de ferro, mutações no gene HFE estão associadas a progressão da fibrose hepática e a carcinoma hepatocelular (CHC) em portadores crônicos VHC. Casuística e Métodos: De um banco de 2300 pacientes matriculados nos Ambulatórios de Hepatologia e de Transplante Hepático do HCFMUSP, selecionaram-se 320 portadores de hepatite crônica C. Os homens (55,6%) apresentaram 50,8 anos de idade em média e as mulheres 54,3. Obtiveram-se dados clínicos e laboratoriais da época da biópsia hepática, admissionais ou com pelo menos um ano de wash-out do tratamento antiviral. Considerou-se sobrecarga bioquímica níveis de ferro, saturação da transferrina e ferritina acima dos valores de referência. Sobrecarga de ferro tecidual foi identificada pela coloração de Perls graus 3-4. As mutações HFE C282Y e H63D foram pesquisadas pela técnica de PCR em tempo real, em DNA extraído de sangue total, após assinatura de TCLE aprovado pelo comitê de ética local. A fibrose hepática foi considerada avançada para graus 3-4 da classificação SBH/SBP e Metavir (n=167, 52,2%). CHC foi definido por biópsia ou por imagem típica por 2 métodos e AFP 400 mg/dL (n=45, 14,1%). Investigaram-se antecedentes de etilismo, diabetes mellitus, IMC e esteatose em biópsia hepática. A partir dos resultados de genotipagem HFE, constituiu-se um subgrupo caso-controle (n=182) com os portadores de mutações e pares de idade, sexo, etnia e IMC similares. Procederam-se análises de correlação bivariada e multivariada (IC=95%) nos grupos geral e caso-controle. Resultados: Quando se compararam casos com fibrose leve vs avançada, observaram-se níveis elevados de ferro em 17,7% vs 25,2% (p=0,019); saturação da transferrina em 24,3% vs 36,7% (p=0,001); ferritina em 25,8% vs 32,4% (p=0,040) e sobrecarga de ferro tecidual em 3,6% vs 1,4% (p=0,126). Quanto à mutação C282Y, observaram-se frequências alélicas de 0,9% vs 2,0% (p=0,110) e à H63D 5,0% vs 8,0% (p=0,033). No subgrupo casocontrole, as associações de C282Y e H63D com fibrose avançada ocorreram com significâncias de p=0,072 e 0,008, respectivamente. A análise multivariada, tendo fibrose como variável dependente nesse mesmo subgrupo, confirmou as associações com C282Y (OR=31,45; p=0,006) e H63D (OR=33,70; p=0,001). Neste mesmo subgrupo, a presença de pelo menos um alelo mutante esteve associada à ocorrência de CHC (p=0,015). Não se identificaram outros parâmetros associados a transformação carcinomatosa. Na análise multivariada, foram variáveis associadas a evolução da fibrose idade avançada (OR=2,36; p=0,000), etilismo (OR=2,18; p=0,007), saturação da transferrina (OR=2,11; p=0,010) e mutação H63D (OR=1,97; p=0,03). Discussão e Conclusões: Houve correlação de graus mais avançados de fibrose com níveis elevados de ferro, saturação da transferrina e ferritina; contudo, esses marcadores também podem estar igualmente elevados nos indivíduos com pouca fibrose. Ao contrário, em muitos casos, a sobrecarga bioquímica de ferro pode ser conseqüência da progressão da doença hepática, e não sua causa. As mutações H63D e C282Y ocorreram em associação com maiores graus de alteração arquitetural; mas, como não houve associação entre siderose tecidual e fibrose, é possível que seu papel na agressão hepática não ocorra diretamente por meio da sobrecarga de ferro. Os portadores de mutações HFE apresentam CHC com maior frequência que seus casos-controle. / Introduction: HCV infection is an epidemic of global proportions, which becomes chronic in about 85% of individuals. Iron overload due to HFE mutations has been proposed as aggravating factor in the evolution of chronic hepatitis C. Objectives: To assess whether iron overload, mutations in the HFE gene are associated with progression of liver fibrosis and hepatocellular carcinoma (HCC) in chronic HCV. Patients and Methods: From a database of 2300 patients enrolled in the outpatient clinics of Hepatology and Liver Transplantation, HCFMUSP, 320 patients with chronic hepatitis C were selected. Men (55.6%) were 50.8 years old on average and women 54.3. Admissional clinical and laboratory data at the time of liver biopsy were obtained; when patient had been previously treated with antiviral drugs, the wash-out period required was of at least one year. Biochemical iron overload was defined as iron, ferritin and transferrin saturation above the reference values. Tissue iron overload was identified by Perls staining of grades 3-4. The HFE C282Y and H63D mutations were searched by real-time PCR technique in DNA extracted from whole blood, after signing of FICT approved by the local ethics committee. The liver fibrosis was considered advanced for grades 3-4 in the classification SBH/SBP and METAVIR(n = 167, 52.2%). HCC was defined by biopsy or by typical image by 2 methods and AFP 400 mg / dL (n = 45, 14.1%). Personal history of alcoholism, diabetes mellitus, BMI and steatosis in liver biopsy were obtained. A casecontrol group was constituted based on the results of HFE genotyping (n = 182), subjects were paired by age, gender, ethnicity and BMI. Bivariate correlation and multivariate analysis (CI = 95%) groups in general and case-control were carried-out. Results: When comparing patients with mild vs advanced fibrosis, biochemical high levels of iron were detected in 17.7% vs 25.2% (p = 0.019), transferrin saturation in 24.3% vs 36.7% (p = 0.001), ferritin in 25.8% vs 32.4% (p = 0.040) and tissue iron overload in 3.6% vs 1.4% (p = 0.126). Regarding to HFE mutations, the allelic frequencies of C282Y were 0.9% vs 2.0% (p = 0.110); and of H63D, 5.0% vs 8.0% (p = 0.033). In casecontrol group, associations of C282Y and H63D with advanced fibrosis occurred with significance of p=0.072 and 0.008, respectively. Multivariate analysis with fibrosis as the dependent variable in that group, confirmed the associations with C282Y (OR = 31.45, p = 0.006) and H63D (OR = 33.70, p = 0.001). In this same subgroup, the presence of at least one mutant allele was associated with occurrence of HCC (p = 0.015). There were not any other parameters found in association with carcinomatous transformation. The multivariate analysis using fibrosis as dependent variable showed association with age (OR = 2.36, p = 0.000), alcoholism (OR = 2.18, p = 0.007), transferrin saturation (OR = 2.11, p = 0.010) and H63D mutation (OR = 1.97, p = 0.03). Discussion and Conclusions: Advanced degrees of fibrosis were correlated with high levels of iron, transferrin saturation and ferritin; however, these markers can also be elevated in individuals with slight fibrosis. In contrary, in many cases, the biochemistry of iron overload may be a consequence of progression of liver disease. C282Y and H63D mutations occurred in association with more advanced fibrosis. However, as there was not any correlation between tissue siderosis and fibrosis, it might be possible that liver injury occurs not by the iron overload pathway. Finally, carriers of HFE mutations were found with HCC more frequently than their casecontrol.

Le traitement utilisé actuellement contre le virus de l’hépatite C présente une efficacité limitée et induit d’importants effets secondaires. La délivrance de molécules antivirales spécifiquement dans les cellules infectées devrait permettre d’améliorer leur efficacité.Ce travail présente le développement d’une nouvelle approche utilisant à son profit la machinerie de réplication virale pour délivrer une molécule antivirale aux seules cellules infectées. Cette stratégie repose sur l’utilisation d’ARN non codants réplicables (nrRNA) portant les structures reconnues par le complexe de réplication du VHC, encadrant la séquence complémentaire d’un gène antiviral. Le complexe de réplication du VHC réplique le nrRNA comme s’il s’agissait du génome viral, permettant ainsi la synthèse d’un ARN codant à partir duquel la molécule antivirale est exprimée. Les cellules non-infectées n’exprimant pas le complexe de réplication, cette machinerie spécifique peut être utilisée et détournée, de façon à cibler les cellules infectées sans impact sur les cellules saines.Nous montrons ici que cette approche s’avère efficace contre le réplicon (génotype 1b) et le virus JFH-1 (génotype 2a) : les nrRNA induisent une forte baisse de la quantité d’ARN et de complexe de réplication viral. Ces effets sont corrélés à une forte activation de la transcription de différents gènes de la réponse IFN de type I.Nous avons également vérifié l’innocuité de ce système sur les cellules non infectée en utilisant des nrRNA RicineA. La réplication et la traduction de ces nrRNA conduit à la mort cellulaire par inactivation des ribosomes. Mais la viabilité des cellules non infectées par le VHC n’est pas perturbée, signe que les nrRNA RicineA ne sont ni répliqués ni traduits en absence du complexe de réplication viral.La vectorisation des nrRNA a également été développée au moyen de particules lentivirales modifiées. Nous testons désormais la réplication et la traduction des nrRNA dans un modèle murin, en vectorisant ces ARN par injection hydrodynamique ou par l’intermédiaire des particules lentivirales. / The current treatment used against Hepatitis C Virus has a limited efficacy and is often hampered by the induction of side-effects. The specific delivery of antiviral proteins in infected cells should increase their efficiency and reduce their impact on healthy cells.Here, we describe the development of a new approach which takes advantage of the viral replication machinery to specifically target the antiviral protein expression to the infected cells. The strategy is based on the delivery of a non-coding replicative RNA (nrRNA) carrying the structures required for the binding of the viral replication complex, flanking the complementary sequence of an antiviral gene. The HCV replication complex replicates the nrRNA similarly to the viral genome to give a coding RNA from which the antiviral protein will be expressed. As non-infected cells do not express the replication complex, this specific machinery can be used to target virus-infected cells without affecting healthy cells.We show that this approach can be successfully applied in both replicon-harboring cells (genotype 1b) and JFH-1 infected cells (genotype 2a) : nrRNAs induced a strong decrease in genomic RNA and viral protein NS5A. These effects were correlated with a strong activation of several interferon stimulated genes.We also verify the harmlessness of the system in uninfected cells by transfecting a RicinA nrRNA. The replication and translation of this nrRNA lead to the cell death by ribosomes inactivation. But nothing occurs in non?infected cells, showing that nrRNA are neither replicated nor translated in absence of the HCV replication complex.The vectorisation of nrRNa was also developed by the use of modified lentivirale particles. We now test the efficient replication and translation of nRNAs in a murin model by using hydrodynamic transfection or the lentiviral delivery of nrRNAs.

Le carcinome hépatocellulaire (CHC) est la tumeur maligne primitive du foie la plus fréquente (90 % des cas). Le CHC est le cinquième cancer par ordre de fréquence à l'échelon mondial, la troisième cause de décès par cancer dans le monde entier et son incidence est actuellement croissante. Parmi Les principaux facteurs prédictifs de survenue de CHC ; les altérations génétiques, l'alcool et les infections par les virus des hépatites B (VHB) et C (VHC). Les travaux de thèse en cotutelle menés entre l’Universités Paris Sud 11-France et l’Université Mohammed V- Rabat –MAROC ont porté essentiellement sur l’étude de deux facteurs de risque impliqués dans le développement du carcinome hépatocellulaire ; le polymorphisme génétique et l’infection par le virus de l’hépatite C. Dans un premier temps, ce travail de recherche s’est focalisée sur l’éventuelle relation pouvant liée les polymorphismes génétiques des gènes PCAF, P300 au carcinome hépatocellulaire. Sur le plan génétique nous avons constaté que les génotypes Val/Val de EP300 et Ser/Ser de PCAF apparaissent comme les plus associés à l’hépatocarcinome. Par ailleurs, ces derniers se trouvent associés d’une manière significative au carcinome hépatocellulaire. Par la suite, notre travail a consisté à mieux caractériser la variabilité génétique du HCV et l’épidémiologie des souches virales chez la population marocaine pour lesquelles peu de données étaient disponibles. Les analyses phylogénétiques des régions NS5B et E2 et les données épidémiologiques recueillies ont permis de répondre à ces questions. Enfin, La dernière partie des travaux de cette thèse vise à identifier des facteurs cellulaires essentiels à la réplication du VHC, dans l’objectif de définir de nouvelles cibles thérapeutiques pour le traitement des hépatites virales C. Nous avons pu identifier la septine 9 comme facteur cellulaire impliqué dans le cycle de vie virale du HCV, ainsi que les protéines PIAS1 et SUMO1 comme protéines régulatrices de la septine 9. De plus nous avons pu établir la relation entre ces protéines cellulaires dont la présence est nécessaire à la fois à la production des protéines virales ( CORE et E2) et à la réplication du virus dans la cellule hôte. / Hepatocellular carcinoma (HCC) is the fifth most common cause of cancer worldwide and the third most common cause of cancer mortality. HCC is one of the few cancers with welldefined major risk factors. Major causes of HCC include hepatitis B, hepatitis C, alcoholic liver disease, nonalcoholic, steatohepatitis, hereditary hemochromatosis, and geneticalteration. The multifactorial causes of HCC might explain its complex molecular pathogenesis. Detailed understanding of epidemiologic factors and molecular mechanisms associated with HCC ultimately could improve our current concepts for screening and treatment of this disease. With a view toward current concepts for screening of this disease, first, we analyzed a genetic susceptibility to hepatocellular carcinoma. The aim of the current study was to assess the impact of the Ile997Val in EP300 and Asn386Ser in PCAF polymorphisms on the risk of HCC. we found that the Val/Val of the EP300 at codon 997 and Ser/Ser of the PCAF at codon 386 were associated with an increased risk of HCC in the Moroccan population. A higher risk of HCC was observed in HCV-negative subjects. We also found that male with Ser/Ser in thePCAF gene and women with Val/Val genotype of the EP300 had a higher risk to develop HCC. It appears that variants of the transcriptional coactivator genes (EP300 and PCAF) may influence HCC risk in populations with low mutations or hromosomal instability rates. Additional surveys are warranted to confirm this first report. The incidence of HCC is increasing in Western countries, mostly because of the high prevalence of hepatitis C virus (HCV) infection. In this sense, we have tried to identify new host factors involved in replication of HCV. Hepatitis C virus (HCV) replicates in the liver,and chronic infection often leads to cirrhosis, steatosis, and hepatocellular carcinoma. There is no vaccine to protect against HCV infection. Major improvement has been recently achieved regarding treatment of HCV infection however there is already evidence for emergence of resistance due to the high genetic variability of the HCV RNA genome. Thus it should be important, to design therapies which avoid genotypic resistance by targeting cellular proteins. Understanding the mechanisms that allow proper assembly and intracellular trafficking of HCV proteins may have a profound impact on the treatment efficacy. An important hallmark of chronic HCV infection is liver steatosis associated with the accumulation of lipid droplets (LDs). The LDs accumulated in the HCV infected cells and the HCV core protein induces the redistribution of LDs, through the clustering of these organelles in the perinuclear area, providing a platform for virus assembly and in the production of infectious particles. Several host proteins have been proposed to facilitate the replication of HCV however much is needed to elucidate the implicated mechanisms. Here we report that HCV infection increases expression and formation of septin 9 filament surrounding HCV core. Data of our study revealed the highest expression of septin 9 in samples from hepatocellular carcinoma (HCC) from patients with chronic HCV infection. Indeed, we brought newperception of septin 9 function regarding both microtubule and lipid structure organization. We proposed that HCV infection conducts to assembly of septin 9 in filaments through PIAS1. This may provide scaffolds to organize the microtubules network and LDs redistribution required for HCV assembly and replication. This study illuminates a new function of septin 9 in HCV life cycle through its association with lipids and microtubules. These events might depend on septin 9 SUMO1 modification by PIAS1. These findings also provide a step forwards in understanding the relationship between HCV and its host and open new therapeutic directions.

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No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Tese_AspectosEpidemilogicosInfeccao.pdf: 1923999 bytes, checksum: e16047905d14555beea73d689c4dee3f (MD5) Previous issue date: 2015-09-24 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / O vírus da hepatite C (HCV) possui grande número de infectados e pode causar hepatocarcinoma. Seu material genético de RNA tem 6 diferentes genótipos (1, 2, 3, 4, 5 e 6) e diversos subtipos, relacionados ao prognóstico da doença e a resposta ao tratamento. A principal rota de transmissão do HCV é a via parenteral, mas a transmissão vertical e intrafamiliar também são relatadas. O uso de drogas e o compartilhamento de perfurocortantes caracterizaram-se como fatores de risco para aquisição da infecção e são vias descritas e confirmadas pela literatura. Pouco se sabe sobre a transmissão viral em comunidades isoladas ou de difícil acesso, como as populações ribeirinhas. Este estudo objetivou determinar a prevalência da infecção viral, avaliar o perfil sorológico e os genótipos circulantes pelo HCV, e traçar as características epidemiológicas, descrevendo os principais fatores de risco para aquisição da infecção pelo HCV a que diferentes comunidades ribeirinhas residentes no Estado do Pará, na Amazônia Oriental, encontram-se expostas. Os entrevistados responderam um questionário para obtenção de informações epidemiológicas e as amostras de sangue periférico foram coletadas para realização dos testes sorológicos, moleculares e genotipagem. Foram coletadas 1.277 amostras das comunidades do Entorno da Usina Hidroelétrica de Tucuruí, Pacuí, Furo do Maracujá e do Nazário. Predominou a faixa etária de 18 a 37 anos, sexo feminino, casados (as), baixa escolaridade, profissão de pescador ou extrator de açaí, com até 1 salário mínimo. Respeitadas as características particulares de cada local, o consumo de álcool e tabaco variou entre as comunidades, assim como o compartilhamento de materiais perfurantes e cortantes, dos kits de manicure, realização de cirurgias, internação hospitalar, presença de IST e se existem familiares com hepatite. O Pacuí apresentou prevalência da infecção pelo HCV de 8,84%, possuindo prevalência moderada da infecção e em Tucuruí foi de 2,25%, próximo à média nacional. O genótipo 1 foi encontrado em 100% das amostras do Pacuí e 70% das amostras de Tucuruí, que possuiu os 30% restantes das amostras pertencentes ao genótipo 3, seguindo o padrão de distribuição genotípica esperado. No Furo do Maracujá e do Nazário, não foram encontradas amostras positivas. As comunidades parecem possuir individualidades que devem ser consideradas para as tomadas de medidas de saúde pública, com risco aumentado de infecção pelo uso de drogas e o compartilhamento de objetos perfurocortantes. A circulação viral possuí prevalência intermediária a moderada, com padrão de distribuição genotípico correspondente ao brasileiro. A distribuição da infecção e suas características podem variar dentro do país e até dentro das próprias regiões, dependendo da presença e da circulação viral, além dos fatores de risco a que as comunidades se encontram expostas. / The hepatitis C virus (HCV) has large number of infected and may cause hepatocellular carcinoma. Its genetic material RNA presents six different genotypes (1, 2, 3, 4, 5 and 6) and subtypes, related by disease prognosis and response to treatment. The main route of transmission of HCV is the parenteral route, but the vertical and intrafamily transmission and is also reported. Drug use and needlestick share were characterized as risk factors for acquisition of infection and pathways are described and confirmed by literature. Less is known about viral transmission in remote or hard to reach communities such as riverside communities. This study aimed to determine the prevalence of viral infection, evaluate the serological profile and circulating genotype HCV, and trace the epidemiological characteristics, describing the main risk factors for acquisition of HCV infection that different riverside communities living in the State of Pará, in the Eastern Amazon, are exposed. The respondents answered a questionnaire to obtain epidemiologic information and blood samples were collected to carry out the serological, molecular, and genotyping tests. 1.277 samples were collected from Surrounding of the Tucuruí Hydroeletric, Pacuí, Hole of Maracujá and Nazário communities. Predominant age group 18-37 years old, female, married, low education, fishermen or açaí extractor, with up to 1 minimum wage. Respecting the particular characteristics of each local, consumption of alcohol and tobacco ranged between communities, as well as sharing the spiked material and cutting, the manicure kits, surgeries, hospitalization, presence of sexually transmitted diseases and if has any familiar with hepatitis. The Pacuí presented prevalence of HCV infection of 8,84 % having moderate prevalence of infection and Tucuruí was 2,25 %, close to the national average. The genotype 1 was found in 100% of Pacuí samples and 70% of Tucuruí samples, which possessed the remaining 30% of the samples belonging to genotype 3, following the pattern expected genotype distribution. In Maracujá Hole and Nazário Hole, there were no positive samples. The communities seem to have individuals who should be considered for the taking of public health measures, with increased risk of infection through drug use and the sharing of needlestick objects. The viral circulation have intermediate to moderate prevalence, with standard genotypic distribution similar to the Brazilian. The distribution of the infection and its features can vary within the country and even within their own regions, depending on the presence and viral circulation, in addition to the risk factors to which comunities are exposed.

L’émergence récente de nouvelles thérapies antivirales efficaces est une avancée considérable pour lutter contre l'infection chronique par le virus de l'hépatite C (VHC). Cependant, un pic de carcinomes hépatocellulaires, représentant l'atteinte hépatique ultime liée à l'infection, est attendu dans la prochaine décennie. Approfondir les connaissances des différentes étapes du cycle viral et de l’interférence du VHC avec l'hépatocyte hôte permet de mieux comprendre la pathogénèse associée à ce virus. Les travaux présentés dans cette thèse ont eu pour objectif d'identifier le réseau de partenaires cellulaires et viraux de la protéine non-structurale NS2 du VHC et de mieux comprendre les mécanismes d'action et de régulation de cette protéine transmembranaire multi-fonctionnelle, qui est un acteur clé du clivage protéolytique de la polyprotéine virale et de la morphogénèse des virions. Dans une première partie, nous avons analysé comparativement les mécanismes moléculaires de l’activité enzymatique des protéines NS2 du VHC et de plusieurs hepacivirus non-humains, qui infectent des primates du Nouveau Monde (GBV-B) ou qui ont été récemment identifiés chez plusieurs autres espèces animales (NPHV, RHV, BHV et GHV). Des analyses phylogénétiques, des modèles structuraux tridimensionnels et des Études dans un contexte d'expression transitoire de précurseurs polypeptidiques viraux ou dans des modèles d'infection ont montré que l’activité des protéases NS2 de divers hepacivirus (1) s'exerce à la jonction NS2/NS3 sous la forme d'homodimères formant deux triades catalytiques composites ; (2) est régulée dans le contexte de la polyprotéine virale par quelques résidus de surface du domaine N-terminal de NS3 (NS3N) nécessaires à son activation ; (3) est efficace en l'absence complète de NS3N, suggérant un rôle négatif ou régulateur, plutôt qu'activateur de NS3N, contrairement au dogme en vigueur actuellement. Ces travaux soulignent l'importance fonctionnelle des mécanismes protéolytiques de NS2 conservés parmi les différents hepacivirus. Dans une deuxième partie, nous avons identifié un réseau de facteurs cellulaires et viraux interagissant avec NS2 au cours du cycle infectieux par un crible interactomique reposant sur la purification par affinité et l'analyse par spectrométrie de masse des complexes protéiques isolés de cellules hépatocytaires infectées, ainsi que par un test de complémentation enzymatique fonctionnelle. Par une approche d'ARN interférence, nous avons ensuite montré qu'un nombre limité de facteurs cellulaires interagissant avec NS2 sont impliqués dans la production et la sécrétion de particules virales infectieuses, incluant des protéines du complexe de la peptidase signal (SPCS) au sein du réticulum endoplasmique, des protéines chaperonnes (DNAJB11, HSPA5) et une protéine impliquée dans le transport intracellulaire (SURF4). Notamment, nos Études suggèrent que plusieurs membres du SPCS forment un complexe multi-protéique avec NS2, impliquant Également la glycoprotéine virale E2, qui jouerait un rôle dans une Étape précoce de l'assemblage ou lors de l’enveloppement de la particule virale. En conclusion, mes travaux de thèse ont permis d'identifier pour la première fois une série limitée de facteurs hépatocytaires interagissant spécifiquement avec la protéine NS2 du VHC au cours de l'infection et de déterminer parmi ceux-ci les facteurs essentiels la morphogenèse virale. Par ailleurs, nos résultats ont permis d’enrichir les connaissances naissantes des hepacivirus non-humains récemment identifiés et de montrer que ceux-ci partageaient avec le VHC des mécanismes clés mis en jeu au cours du cycle viral, ce qui contribue consolider leur intérêt comme modèles animaux de substitution. / The recent emergence of a panel of direct acting antivirals will certainly help combat chronic hepatitis C in the future. However, in the current context worldwide, a peak of hepatitis C virus (HCV)-induced hepatocellular carcinoma is expected in the next decade. Deepening our understanding of HCV life cycle and HCV interference with host cells may help monitor HCV-associated pathogenesis. The aim of my PhD work was to identify the network of host and viral interactors of HCV nonstructural protein 2 and to unravel the mechanisms of action and regulation of this multifunctional, transmembrane protein, which is key both for the viral polyprotein cleavage and virion morphogenesis.In the first part of the work, we comparatively characterized molecular mechanisms underlying the enzymatic activity of NS2 proteins from HCV and from various non-human hepaciviruses that infect small New World primates (GBV-B) or that were recently identified in the wild in several mammalian species (NPHV, RHV, BHV, GHV). A combination of phylogenetic analyses, tridimensional structural models, and studies relying on the transient expression of viral polypeptide precursors or on infection models showed that NS2 proteases of the various hepaciviruses (1) act as dimers with two composite active sites to ensure NS2/NS3 junction cleavage, (2) are regulated in the polyprotein backbone via a hydrophobic patch at the surface of NS3 N-terminal domain (NS3N) that is essential to activate NS2 protease, and (3) are efficient in the complete absence of NS3N, which is unprecedented and suggests that NS3N has rather a negative or regulating role on NS2 activity. These data underline the functional importance of NS2 proteolytic mechanisms that are conserved across hepaciviruses.In the second part, we identified a network of cellular factors and viral proteins that interact with NS2 in the course of HCV infection using an interactomic screen based on affinity purification and mass spectrometry analysis of protein complexes retrieved form HCV infected hepatoma cells, as well as a split-luciferase complementation assay. Next, using a gene silencing approach, we found that a limited set of NS2 interactors among these host factors were involved in HCV particle assembly and/or secretion. This includes members of the endoplasmic reticulum signal peptidase complex (SPCS), chaperone proteins (DNAJB11, HSPA5) and a factor involved in intracellular transport (SURF4). Notably, our data are in favor of the existence of a multiprotein complex involving NS2, several members of the SPCS, and the viral E2 glycoprotein, which likely plays a role in an early step of HCV particle assembly or during particle envelopment. Altogether, my PhD work allowed us to identify a limited set of hepatocyte factors interacting with HCV NS2 during infection and to pinpoint those that are essential for HCV morphogenesis. Additionally, our results contributed to the molecular characterization of the recently identified non-human hepaciviruses and revealed that these hepaciviruses share with HCV key mechanisms in the course of their infectious life cycles. This highlights the value of non-human hepaciviruses as surrogate animal models of HCV infection.

Chronic HCV infection causes generalized CD8+T cell impairment, not limited to HCV-specific CD8+ T cells. Infiltrating monocyte-derived macrophages contribute to a micro- environment that could impact CD8+T cells trafficking through the liver. Macrophages can differentiate into pro-inflammatory (M1) and anti-inflammatory (M2a, M2b, and M2c) subsets. Whether macrophage subset generation in chronic HCV infection is altered and if that has a subsequent impact on CD8+T cell functions was not known. I have shown phenotypic alterations in both M1 and M2 macrophages in chronic HCV infection. In particular, M1 from advanced fibrosis patients show increased CD86 expression, reduced spontaneous TNF-α and increased spontaneous IL-10 production. In uninfected controls, co-culturing CD8+T cells with M1 macrophages significantly increased the percentage of CD107a+ and IFN-γ+ CD8+T cells in a contact-dependent manner. Similar autologous co-cultures between M1 and CD8+T cells from patients with chronic HCV infection showed that M1 significantly reduced the percentage of IFN-γ+ CD8+T cells, even though patients displayed elevated IFN-γ+CD8+ T cells at baseline prior to culture. Overall, I demonstrated the altered phenotype of macrophages generated from patients with chronic HCV infection. I also showed the ability of M1 macrophages to induce IFN-γ+CD8+T cells in normal donors and their opposite impact when the cells are derived from chronic HCV infected patients.