Malaria is a widespread parasitic disease, causing 300-500 million infections per year and resulting in over 1 million deaths. There is widespread resistance of the parasite to most of the antimalarial treatments available, indicating the need for a vaccine (http://www.rbm.who.int/wmr2005/). The translationally controlled tumour protein (TCTP) family are highly conserved eukaryotic proteins that have been assigned a variety of functions. While most studies have focused on the intracellular functions of TCTP, human, malarial and other parasitic TCTPs have also been reported to have extracellular functions in the induction of histamine release from immune cells (e.g. MacDonald et al., 2001; Rao et al., 2002). Malarial TCTP has been detected in the sera of malaria-infected individuals (MacDonald et al., 2001) and is also known to bind to the antimalarial drug artemisinin (Bhisutthibhan et al., 1998). In this study, TCTP was investigated as a malarial vaccine candidate due to a previously observed protective effect in mice infected with Plasmodium yoelii YM. In that study, PfTCTP immunisation conferred a significant delay in disease progression, as judged by reduced parasitemia and prolonged survival (Taylor, 2002). It was thought that the protective effect might have been due to the inhibition of the extracellular actions of malarial TCTP by the acquired host immune response. P. falciparum and P. yoelii TCTP were initially expressed in S. cerevisiae, as in the previous study. The recombinant proteins were used to vaccinate mice, which were then challenged with two strains of P. yoelii. No protective effect was observed for either vaccine, and so the previous results using PfTCTP could not be confirmed. The TCTP of P. yoelii and P. berghei were then expressed in E. coli, which increased yield and decreased proteolysis. The recombinant proteins were used as vaccines in mice challenged with P. yoelii YM, P. c. chabaudi AS, or P. berghei ANKA. A significant delay in disease progression was observed in PyTCTP-immunised mice challenged with the non-lethal P.c. chabaudi, as determined by a significantly reduced parasitemia at each day post-infection leading up to a delayed peak parasitemia. A significant reduction in parasitemia was also observed in the early stages of P. yoelii YM infection in PyTCTP-immunised mice. P. berghei ANKA was used to challenge C57BL/6 mice to determine whether PbTCTP immunisation could protect mice from cerebral malaria development, no protective effect was observed. P. berghei ANKA was also used as a second lethal malaria challenge model in BALB/c mice, no significant differences in disease progression were observed in immunised mice. To further assess the functions of malarial TCTP, several attempts were made to create a TCTP-knockout strain of P. berghei ANKA. A TCTP-knockout malaria strain could be assessed for alterations in morphology, infectivity and artemisinin sensitivity compared with wild-type parasites. Initial genotype analysis of parasites resulting from several transfection experiments indicated that TCTP disruption had been successful, however TCTP-disrupted parasites were strongly selected against, and stable knockout strains could not be obtained. This indicates that TCTP performs an important role within the malaria parasite.

Submitted by Marco Antônio de Ramos Chagas (mchagas@ufv.br) on 2018-08-24T18:20:21Z No. of bitstreams: 1 texto completo.pdf: 484015 bytes, checksum: fda75b7a7bc67b7a6301406613010fcd (MD5) / Made available in DSpace on 2018-08-24T18:20:21Z (GMT). No. of bitstreams: 1 texto completo.pdf: 484015 bytes, checksum: fda75b7a7bc67b7a6301406613010fcd (MD5) Previous issue date: 2017-07-26 / Fundação de Amparo à Pesquisa do Estado de Minas Gerais / Os vírus são as formas de vida mais abundantes e geneticamente diversas conhecidas em nossa biosfera. Para infectar hospedeiros com sucesso, os vírus manipulam componentes celulares do hospedeiro, recrutando fatores do hospedeiro necessários para replicação, infeção e transmissão. Além disso, os vírus precisam suplantar diversas estratégias de defesa do hospedeiro levando a um complexo mecanismo de coevolução que envolve diversas interações. Diferentes vírus podem interagir com componentes celulares do hospedeiro de forma semelhante. Foi demonstrado que a presença da proteína translationally controlled tumor protein (TCTP) é necessária para o estabelecimento de uma infecção eficiente por potyvírus. TCTP é uma proteína multifuncional encontrada em quase todos os eucariotos envolvida no crescimento celular, homeostase de íons, reparo de danos no DNA e possuí atividade anti-apoptótica. Apesar de inúmeros estudos com TCTP, o envolvimento desta proteína na infecção viral ainda não é totalmente compreendido. Devido a sua diversidade funcional, é possível imaginar que TCTP possa ser um fator do hospedeiro envolvido em infeções causadas por vírus de diferentes grupos. Desta forma, neste trabalho, foi avaliado o efeito de TCTP na infecção por begomovírus. Para isso, plantas de Nicotiana benthamiana com TCTP silenciada por VIGS foram utilizados para estudar o efeito da TCTP na infecção pelo begomovírus Tomato yellow spot virus (ToYSV). O silenciamento de TCTP levou a um maior acúmulo de vírus, sugerindo que TCTP é um fator do hospedeiro envolvido no processo de defesa á infecção viral. Além disso, o mRNA de TCTP é altamente estruturado em mamíferos e está relacionado com a indução de resposta a infecções por diferentes vírus. Por ser um mRNA altamente estruturado é razoável supor que o mRNA de TCTP pode ser alvo do processo de silenciamento pós transcrisional da planta levando à produção de pequenos RNAs de interferência (siRNAs) através da clivagem por proteínas Dicer e os siRNAs gerados podem regular a expressão de genes endógenos do hospedeiro. Desta forma, foi realizada uma análise in silico para avaliar os possíveis siRNAs gerados a partir do silenciamento do mRNA de TCTP e os possíveis alvos desses siRNAs. Genes que podem estar envolvidos em infecção viral, como aqueles que codificam proteína kinases, proteínas envolvidas na via de ubiquitinação, fatores de transcrição e tradução e proteínas de ligação ao cálcio foram alguns dos genes identificados como possíveis alvos destes siRNAs. / Viruses are the most abundant and genetically diverse life forms known in our biosphere. To successfully infect hosts, viruses manipulate host cellular components, recruiting host factors necessary for replication, infection, and transmission. In addition, viruses need to supplant various host defense strategies, leading to a complex coevolution mechanism involving virus-host interactions. Different viruses can interact with host cell components similarly or even antagonistic. The presence of the protein translationally controlled tumor protein (TCTP) has been shown to be necessary for the establishment of an efficient potyvirus infection. TCTP is a multifunctional protein found in almost all eukaryotes and is involved in cell growth; ions homeostasis; DNA damage repair and anti-apoptotic activity. Despite numerous studies with TCTP, the involvement of this protein in viral infection is not yet fully understood. Due to its functional diversity, it is possible to imagine that TCTP may be a host factor involved in infections caused by viruses of different groups. Thus, in this work, the effect of TCTP on begomovirus infection was evaluated. Nicotiana benthamiana plants silenced for TCTP by VIGS experiments were used to study the effect of TCTP expression on infection by the begomovirus Tomato yellow spot virus (ToYSV). TCTP silencing led to higher accumulation of the virus, suggesting that TCTP is a host factor involved in viral infection defense process. Furthermore, TCTP mRNA is highly structured in mammals and is related to the induction of defense response to different viruses. Because it is a highly structured mRNA, it is reasonable to assume that TCTP mRNA may be the target of the plant post transcription gene silencing mechanism, leading to the production of small interfering RNAs (siRNAs) by the cleavage of Dicer proteins and the siRNAs generated might regulate the expression of host endogenous genes involves in virus infection. In silico analysis was performed to evaluate the possible siRNAs generated from the silencing of TCTP mRNA, and the respective targets of this siRNAs. Genes involved in viral infection, such as those encoding protein kinases, proteins involved in the ubiquitination pathway, transcription and translation factors, and calcium binding proteins were some of the genes identified as possible targets of these predicted siRNAs.

Das translationell kontrollierte Tumorprotein (TCTP) ist ein hochkonserviertes, ubiquitär in Eukaryonten vorkommendes Protein. Seine Bezeichnung geht auf die erstmalige Beschreibung in Tumorzellen zurück und weist zugleich auf seine besondere translationelle Regulation hin. Das zugehörige Gen wird als TPT1 bezeichnet und befindet sich beim Menschen auf dem langen Arm des Chromosom 13. Eine pathophysiologische Bedeutung für TCTP wurde bei Tumorerkrankungen, Erkrankungen des allergischen Formenkreises sowie bei Infektionen durch Parasiten beschrieben. Für diese Arbeit wurde zur Untersuchung grundlegender Regulationsphänomene die TCTP-mRNA des Kaninchens als geeignetes Modell ausgewählt. Es wurden die volllangen TCTP-mRNA1 und 2, die sich in der Länge ihrer 3'UTR unterscheiden, sowie Deletionsvarianten, denen die UTR-Abschnitte fehlen, kloniert. In Proteinbindungsstudien (Electromobility Shift Assays, UV-Crosslinking-Experimente, RNA-Affinitätschromatographie) wurden potentielle Bindungsfaktoren der TCTP-UTRs analysiert. Die an der mRNA des Kaninchens erarbeiteten Ergebnisse wurden durch Untersuchungen an humanen Melanomzellen ergänzt. In in vitro Translationsexperimenten wurde gezeigt, dass die Regulation der TCTP-mRNA durch ihre 5'UTR und 3'UTR2 vermittelt wird. In RNA-Bindungsstudien konnte eine Reihe potentieller Bindungsfaktoren der UTRs charakterisiert werden. Bei Verwendung von Extrakten aus verschiedenen Kaninchengeweben zeigten sich deutliche gewebsspezifische Unterschiede. Frühere Untersuchungen hatten gezeigt, dass es in der Melanomzelllinie MeWo bei der Ausbildung einer Chemoresistenz zu einer Expressionssteigerung des TCTP kommt. In einem ersten Schritt wurde der Beitrag von Transkription und Translation in vergleichenden Northern und Western Blot Analysen untersucht. Auf mRNA-Niveau findet man in den resistenten Zellen eine deutliche Steigerung der Expression im Vergleich zu den sensiblen Zellen. Der mRNA-Menge in den chemosensiblen Zellen steht eine vergleichsweise geringe Menge an Protein gegenüber. Folglich liegt die mRNA in diesen Zellen in einem inaktiven Zustand vor. Es konnten drei Cytoskelettproteine gamma-Actin, beta-Tubulin und alpha-Actinin als Bindungspartner der TCTP-3'UTR in den Melanomzellen identifiziert werden. Eine Bedeutung von TCTP für die Entstehung der Chemoresistenz lässt sich aufgrund seiner anti-apoptotischen Wirkung vermuten. Die Regulation der TCTP-Translation stellt bei durch Cytostatika hervorgerufener Hemmung der Transkription einen wichtigen Pathomechanismus in chemoresistenten Melanomzellen dar. / The translationally controlled tumor protein (TCTP) is a highly conserved protein expressed in all eukaryotic organisms. It was first described in tumor cells showing a special regulation of translation. The chromosomal localisation of the respective human gene TPT1 has been determined (13q14). TCTP has been implicated in cellular processes such as cell growth and apoptosis. Its medical importance has been shown in malignant transformation, allergic reactions and immunity against parasitic organisms. In order to investigate basic mechanisms of translational regulation the rabbit TCTP-mRNA was chosen due to its high homology to its human counterpart. The TPT1 gene is transcribed into two TCTP-mRNAs differing in the length of their 3'untranslated regions. These two mRNAs and variants missing the untranslated regions were cloned into expression vectors. In Electro mobility shift assays, UV-crosslinking assays and RNA affinity purification several TCTP-mRNA binding factors were characterised. Furthermore, the role of TCTP in human chemoresistant melanoma cells was investigated. In cell-free translation assays the importance of the 5'UTR and 3'UTR2 was shown. However, in wheat germ extracts the regulation of the TCTP-mRNA mediated by its 5'UTR is less important. In Electro mobility shift assays and UV-crosslinking assays with radiolabelled transcripts of the untranslated regions great variations in tissue-specific protein binding were found. Recently, TCTP had been implicated in the development of chemoresistance in the human melanoma cell line MeWo. As a first step, the contribution of transcriptional and translational regulation was analysed by comparing TCTP-expression in Northern and Western blot assays. Transcription of the TPT1 gene is increased in chemoresistant melanoma cells whereas translation is inhibited in those cells susceptible to chemotherapeutic agents. Three proteins, gamma-actin, beta-tubulin and alpha-actinin, were identified as factors binding to the TCTP-3'UTR in melanoma cells. For the interaction of these cytoskeleton components their ability to bind intracellular calcium ions could be of great importance. The role of TCTP in the development of chemoresistance can be explained by its anti-apoptotic function. In conclusion, the regulation of TCTP-translation when transcription is blocked by inhibitors of DNA-function is an important mechanism to overcome the effect of these anti-proliferative agents.

La thématique du laboratoire de l’équipe d’Adam Telerman porte sur la réversion tumorale, un processus rare au cours duquel les cellules cancéreuses perdent leur phénotype malin, et deviennent des cellules dites révertantes. Plusieurs protéines clefs impliquées dans cette transformation ont été mises en évidence, dont TCTP (Translationally Controlled Tumor Protein). La protéine TCTP est également impliquée dans la régulation de l’apoptose en interagissant et en renforçant l’activité anti-apoptotique de Mcl-1 et de Bcl-xl, deux protéines appartenant à la famille des Bcl-2. Ce projet s’attache à comprendre en termes moléculaires le mode d’action de TCTP au cours de l’apoptose. / Adam Telerman’s team research focuses on tumor reversion, a rare process in which cancer cells lose their malignant phenotype, and therefore become revertant. Many key proteins were showed to be involved in this transformation, including TCTP (translationally Controlled Tumor Protein). TCTP protein is also involved in apoptosis regulation by interacting and strengthening the anti-apoptotic activity of Mcl-1 and Bcl-xl, two proteins from Bcl-2 family.

La réversion tumorale est un événement naturel qui conduit les cellules cancéreuses à retrouver spontanément un phénotype tumoral significativement atténué. Ce processus de reprogrammation cellulaire survient très rarement (au rythme d’une cellule par million), et suggère que des composés (petites molécules chimiques) seraient susceptibles de stimuler la réversion tumorale dans le but de constituer une nouvelle classe de médicaments novateurs pour soigner des patients atteints du cancer. Pour ce faire, la protéine TCTP (« Translationally Controlled Tumor Protein ») a été identifiée comme étant une cible moléculaire majeure dans la réversion tumorale. Par conséquent, identifier des composés capables de stimuler cette réversion, par inhibition de la protéine TCTP, constitue une nouvelle stratégie prometteuse dans le traitement des cancers.Dans ce contexte, ce projet de thèse vise à concevoir et synthétiser de nouveaux inhibiteurs de la protéine TCTP, des analogues de la sertraline, un médicament actuellement sur le marché en tant qu’antidépresseur, mais ayant montré une efficacité significative dans le phénomène de réversion tumorale. Dans un second temps, ces analogues seront testés lors de contrôles variés (affinité, cytotoxicité, processus ADMET, etc.) afin de déterminer un "pré-lead" qui sera finalement évalué in vivo. De plus, ces travaux de recherches sont aussi axés sur les optimisations des méthodes initialement utilisées, ainsi que le développement de nouvelles voies de synthèse innovantes pour la formation des inhibiteurs de la protéine TCTP. / Tumor reversion is a natural process that was discovered for the first time in the early 1960s. It is a biological phenomenon by which highly tumorigenic cells lose at great extent or entirely their malignant phenotype. This is a rare molecular program (one cell for a million cancer cells) which suggests that organic compounds could stimulate this process and form a new class of medicinal products susceptible to treat cancer patients. For those purposes, the translationally controlled tumor protein (TCTP) has been identified as a major therapeutic target of tumor reversion. Consequently, identification of products that are capable of stimulating this phenomenon, by TCTP inhibition, will constitute a promising new strategy for the treatment of the disease.In this context, the goal of this thesis is to design and synthesis new TCTP inhibitors, analogues of sertraline. This latter is a widely used antidepressive drug but it also shows significant efficacy throughout the tumor reversion program. In the second part, those analogues will undergo diverse biological essays (affinity, cytotoxicity, ADMET process…) in the aim of identifying a potential lead compound which will be evaluate under in vivo conditions. Moreover, this research is also focus on the optimizations of the first synthetic route and the development of innovative methods to access to those new TCTP inhibitors.

TCTP est une protéine de 20 kDa que l’on retrouve souvent sous forme de dimère. Elle est fortement conservée dans la phylogénie et on la trouve dans les levures, les plantes, les invertébrés et les mammifères. Elle est localisée dans tous les compartiments de la cellule : noyau, cytoplasme, et membranes. Il s’agit d’une protéine très abondante dans des cellules souches ainsi que des cellules en croissance exponentielle, y compris les cellules tumorales. Sa fonction principale est celle d’une « protéine de survie ». TCTP a été décrite comme interagissant avec de multiples protéines dont p53, MDM2, Bcl-xL et TSAP6. Le but de mon travail est de permettre de mieux caractériser ces fonctions de TCTP et pour cela, nous avons étudié ses interactions in vitro et surtout, in vivo, dans différents modèles génétiques chez la souris. / TCTP is a 20 kDa protein frequently encountered as a dimer. It is highly conserved through phylogeny and is present inn yeast, plants, invertebrates and mammals. It is localized in all compartments of the cell: nucleus, cytoplasm, membranes. This protein is highly abundant in stem cells and during the exponential growth, including in cancer cells. It mainly functions as a survivor factor. TCTP has been described as interacting with multiple proteins, including p53, MDM2, Bcl-xL and TSAP6. The purpose of my work is to better characterize these functions of TCTP; we therefore studied its interactions in vitro, but mostly in vivo, using different murine genetic models.

Made available in DSpace on 2015-03-26T13:42:18Z (GMT). No. of bitstreams: 1 texto completo.pdf: 2907131 bytes, checksum: 7c8c658c01f5e065741077a77ef12f4d (MD5) Previous issue date: 2011-02-28 / Fundação de Amparo a Pesquisa do Estado de Minas Gerais / The genomes of most plant viruses code for only 4-10 proteins which are required to complete the infection cycle, including the stages of viral genome replication, cell-to-cell movement and systemic spread. For a successful infection, these viral proteins must interact with host factors, modulating metabolic pathways and coordinating a complex network of biochemical and molecular interactions in the pathogen s favor. A subtractive library constructed from susceptible tomato plants infected by the plant potyvirus Pepper yellow mosaic virus (PepYMV) identified several genes which are putatively involved in the initial steps of the viral infection process, including those that code for the Translationally Controlled Tumor Protein (TCTP) and the tomato homologue of the Saccharomyces cerevisae Gal83 (Sl-Gal83), a protein of the SNF1 complex. TCTP is a highly conserved protein in eukaryotes, and is involved in several fundamental cellular processes such as cell growth, cell cycle progression, programmed cell death and protection against different types of stresses. SNF1 plays an important role in transcriptional activation and expression of genes involved in the cellular response to different stresses, such as nutrient limitation, high salinity, heat shock and virus infection. The objectives of this work were to study the roles of TCTP and Sl-Gal83 during PepYMV infection in susceptible hosts. Transgenic tomatoes (cv. 'Moneymaker') silenced for these genes were generated and were mechanically inoculated with PepYMV. ELISA and qRT-PCR were performed to verify the phenotype resulting from Sl-Gal83 and TCTP silencing. The results showed that non-transformed plants were infected, while all ten silenced plants remained symptomless, were ELISA negative and had reduced viral load. The subcellular localization of TCTP in healthy and PepYMVinfected plants was analyzed by confocal microscopy using a TCTP-YFP fusion. In healthy plants the subcellular localization of TCTP is cytoplasmatic, as described for other organisms. Forty-eight hours after PepYMV infection, TCTP is relocated to the nucleus. To determine which PepYMV protein(s) promotes nuclear targeting of TCTP, each viral protein (P1, HC-Pro, P3, PIPO, P3N-PIPO, CI, 6K2, NIa, NIb and CP) was coexpressed individually with pYFP-TCTP. Results showed that TCTP accumulates predominantly in the nucleus when co-infiltrated with CI and NIa, and is distributed equally in the nucleus and cytoplasm when co-infiltrated with P1, PIPO, P3N-PIPO, 6K2 and NIb. In plants co-infiltrated with HC-Pro, P3 and CP, TCTP remained in the cytoplasm. In order to identify and characterize additional viral and host factors involved in the TCTP-mediated network of plant-potyvirus interactions, TCTP was cloned as a TAP (tandem affinity purification) tag fusion.Protein complexes were purified using TAP, and its constituents were analyzed by mass spectrometry. However,it was not possible to identify the proteins. The probable limiting factor for a more efficient detection was the low concentration of protein eluted. Thus, it is necessary to optimize the protocol of extraction/elution to obtain a higher concentration of proteins complexed with nTAPi- TCTP. Together, the results of this work indicate that both TCTP and Sl-Gal83 play critical roles in the tomato-PepYMV interaction, being necessary for the establishment of a systemic infection. Further studies should be conducted to improve our understanding of the nature and mechanisms of the interactions between TCTP, Sl-Gal83 and PepYMV. / O genoma da maioria dos vírus que infectam plantas codifica apenas 4-10 proteínas, que são necessárias para completar o ciclo de infecção, incluindo as etapas de replicação do genoma viral, movimento célula-a-célula e movimento sistêmico. Para uma infecção bem sucedida, as proteínas virais devem interagir com fatores do hospedeiro, modulando processos metabólicos e coordenando uma rede complexa de interações bioquímicas e moleculares a favor do patógeno. Uma biblioteca subtrativa foi construída a partir de plantas de tomateiro suscetíveis infectadas pelo potyvírus Pepper yellow mosaic virus (PepYMV). Foram identificados vários genes potencialmente envolvidos nas etapas iniciais do processo de infecção viral. Dentre os genes identificados encontram-se os genes que codificam as proteínas Translationally controlled tumor protein (TCTP) e o homólogo de tomate de Saccharomyces cerevisae Gal83 (Sl-Gal83), uma proteína do complexo Sucrose non-fermenting-1 (SNF1). TCTP é uma proteína altamente conservada em eucariotos, e está envolvida em vários processos celulares básicos, como crescimento celular, progressão do ciclo celular, morte celular programada e proteção contra diversos tipos de estresses. SNF1 desempenha um papel importante na ativação da transcrição e expressão de genes envolvidos na resposta celular aos diferentes tipos de estresses, tais como limitação de nutrientes, salinidade elevada, choque térmico e infecção viral. O objetivo deste trabalho foi estudar o papel das proteínas TCTP e Sl-Gal83 durante o processo de infecção pelo PepYMV em hospedeiros suscetíveis. Plantas transgênicas de tomate cv. Moneymaker silenciadas para estes genes foram produzidas e inoculadas mecanicamente com o PepYMV. O estabelecimento da infecção viral foi avaliado por ELISA e qRT-PCR. Plantas não-transformadas foram infectadas, enquanto as plantas silenciadas permaneceram assintomáticas. Nas plantas silenciadas o ELISA apresentou resultado negativo e a carga viral foi reduzida. A localização subcelular de TCTP em plantas sadias e infectadas pelo PepYMV foi analisada por microscopia confocal utilizando-se uma fusão YFP-TCTP. Em plantas sadias a localização subcelular de TCTP é citoplasmática, conforme descrito para outros organismos. Quarenta e oito horas após a infecção pelo PepYMV, TCTP foi redirecionada para o núcleo. Para determinar qual é a proteína viral que direciona a relocalização de TCTP para o núcleo, cada uma das proteínas virais (P1, HC-Pro, P3, PIPO, P3N-PIPO, CI, 6K2, NIa, NIb e CP) foi coinfiltrada individualmente com pYFP-TCTP. Os resultados mostraram que TCTP acumula predominantemente no núcleo quando co-infiltrada com CI e NIa, e está igualmente distribuída no núcleo e citoplasma, quando co-infiltrada com P1, PIPO, P3NPIPO, 6K2 e NIb. Em plantas co-infiltradas com HC-Pro, P3 e CP, TCTP permaneceu no citoplasma. Para identificar possíveis proteínas virais e/ou do hospedeiro que interagem com TCTP foi realizado um ensaio de purificação por afinidade em tandem. A análise por SDS-PAGE de extratos protéicos de plantas expressando nTAPi-TCTP mostrou duas bandas entre 40 e 50 kDa presentes no extrato purificado. Os fragmentos foram analisados por espectrometria de massa, porém não foi possível identificar as proteínas. Provavelmente o limitante para uma detecção mais eficiente foi a baixa concentração de proteínas eluídas. Com isso, torna-se necessário a otimização do protocolo de extração/eluição para a obtenção de uma maior concentração de proteínas complexadas com nTAPi-TCTP. Em conjunto, os resultados obtidos neste trabalho sugerem que tanto TCTP quanto Sl-Gal83 possuem papéis fundamentais na interação PepYMV-tomate, sendo necessárias para o estabelecimento de uma infecção sistêmica. Estudos adicionais devem ser realizados para melhor compreensão da natureza e dos mecanismos das interações entre TCTP, Sl-Gal83 e o PepYMV.

Le cancer de la prostate (CaP) représente la deuxième cause de mortalité par cancer. La suppression d’androgène est la thérapie de référence, du fait de l’androgéno-dépendance de ce cancer. Toutefois, la maladie progresse quand même vers un stade androgéno-indépendant 2 à 3 ans après le début du traitement. Pour améliorer les thérapies du CaP, notre stratégie consiste à cibler les gènes activés par la privation d’androgènes. Récemment, nous avons identifié TCTP (Translationally controlled tumor protein) comme étant hautement surexprimé après privation d’androgènes. Nous avons développé et breveté un oligonucléotide antisense (ASO) ciblant TCTP. Durant ma thèse j’ai développé un ASO de 3ème génération par ajout d’une séquence lipidique TCTP-LASO pour améliorer la stabilité, la biodisponibilité et la délivrance de l’ASO TCTP. Ce LASO est capable de s’autonanovectoriser et permet une internalisation de l’ASO sans agent transfectant. J’ai montré dans les modèles animaux que cela conduit à une meilleure efficacité thérapeutique sans engendrer de toxicité. De plus cette séquence peut servir de nanovecteur pour encapsuler la chimiothérapie. / Prostate cancer (PC) represents one of the most common cancers in industrialized countries. Androgen ablation is used as first-line therapy in patients with advanced disease. While most patients initially respond to this hormonal therapy, they eventually become unresponsive and recur within 2 years as castration-resistant prostate cancer (CRPC). Our strategy to improve therapies involves targeting genes that are activated by androgen withdrawal, to prevent the emergence of CRCP. We have identified the Translationnaly controlled Tumor protein (TCTP) as highly over-expressed in CRPC. We developed and patented an oligonucleotide antisense (ASO) targeting TCTP. During my PhD I developed a 3rd generation ASO (TCTP-LASO) by using a lipid-conjugated oligonucleotides modification in order to improve stability, biodisponibility and delivery of the ASO. This LASO can autonanovectorize, which permits cellular uptake without transfecting agents. This autonanovectorization leads to enhanced tumor regression in vivo without toxicity in animal models. Finally, LASO can be used as a nanovector, in which chemotherapy can be encapsulated to promote its delivery.

Le cancer de la prostate représente la deuxième cause de décès liée au cancer. Des stratégies thérapeutiques ciblant des mécanismes moléculaires conduisant à la résistance doivent donc être développées. Une stratégie visant à améliorer les traitements du cancer de la prostate consiste à cibler les gènes qui sont activés lors de la disparition des androgènes, soit pour retarder ou empêcher l'émergence du phénotype de résistance à la castration. Le but de cette thèse est d'identifier et de développer des petites molécules inhibitrices ciblant des interactions protéine-protéine impliquées dans le cancer de la prostate. Cette thèse porte sur l'étude de deux protéines cruciales liées au cancer de la prostate, à savoir, la protéine de choc thermique de bas poids moléculaire (Hsp27) et la protéine TCTP. Nous avons validé deux composés ciblant TCTP en utilisant une chimiothèque dédiée à l'inhibition d'interaction protéine-protéine. Des tests fonctionnels sont actuellement mis au point pour évaluer la capacité de ces molécules à être proposées comme composés potentiels contre le cancer de la prostate. / Prostate Cancer (PCa) is one of most common malignancies, being the second leading cause among cancer-related death. Additional therapeutic strategies targeting molecular mechanisms mediating resistance must be developed because of the defects of docetaxel-based treatments. One strategy to improve therapies in advanced PCa involves targeting genes that are activated by androgen withdrawal, either to delay or prevent the emergence of the CR phenotype. The purpose of my thesis is to identify & develop small molecules inhibitors targeting PPIs involved in prostate cancer. we focuses on 2 crucial prostate cancer related proteins, namely, the small molecular weight Heat shock protein 27 (Hsp27) and the Translationally Controlled Tumor Protein (TCTP). We have validated 2 compounds targeting TCTP by using a "PPI Inhibitor-like" dedicated chemical library. Functional tests are now being developed to evaluate the capacity of such molecules to be proposed as potential compounds against prostate cancer.

Bien que les plantes et les animaux diffèrent largement par plusieurs aspects, certaines fonctions biologiques sont extrêmement conservées entre ces deux règnes. Au cours du développement d’un organisme, la mise en place d’un organe possédant une forme, une taille et une fonction précise résulte de la coordination de plusieurs processus cellulaires tel que la prolifération et l’expansion cellulaire. Translationally Controlled Tumor Protein (TCTP) est une protéine très conservée chez tous les eucaryotes. Sa mutation entraine une létalité au stade embryonnaire, démontrant son importance dans le développement de l'organisme. De plus, il a été montré que TCTP contrôlait la croissance des organes en régulant la progression du cycle cellulaire et plus particulièrement la transition G1/S chez les plantes et les animaux. Chez les animaux, les voies moléculaires par lesquelles TCTP contrôle la prolifération cellulaire commencent à être de mieux en mieux décrites. En revanche chez les plantes, ces mécanismes restent très peu connus. Afin de comprendre plus précisément comment TCTP contrôle la prolifération cellulaire et le développement chez Arabidopsis thaliana, les intercateurs potentiels de TCTP ont été identifiés. Parmi eux, CSN4, une sous-unité du complexe COP9 Signalosme (CSN) a été trouvée. CSN est connue pour être impliquée dans le contrôle de l’état de neddylation des CULLINES (CUL) et donc influencent l’activité des complexes CULLIN-RING ubiquitine ligases (CRLs). Les CRLs, par leur activité d’ubiquitination, sont connus pour contrôler l’accumulation de certains acteurs clés du cycle cellulaire, tel que les Cyclines ou les Kip Related Proteins. Au cours de ma thèse, j’ai donc étudié l’interaction entre TCTP et CSN4, afin d’évaluer si le complexe CSN pouvait être l’intermédiaire moléculaire entre TCTP et le cycle cellulaire. Via des approches génétique, biochimiques et cellulaires j’ai pu montrer que TCTP interagissait physiquement avec CSN4 dans le cytoplasme. De plus, par la caractérisation phénotypique de plantes et de cultures cellulaires sur- ou sous-exprimant ces deux gènes, j’ai pu mettre en évidence que TCTP et CSN4 interagissaient génétiquement et que ces deux protéines contrôlaient la transition G1/S du cycle cellulaire. Dans le but de comprendre si l’interaction entre ces deux protéines pouvait interférer avec la fonction du complexe CSN, j’ai analysé par une approche biochimique l’état de neddylation de CUL1 dans les lignées transgéniques. Les données démontrent que la perte de fonction de TCTP accroit la fraction déneddylée de CUL1, alors que sa surexpression augmente la fraction de CUL1 neddylée. Ces données suggèrent que l’interaction est fonctionnelle et que TCTP interfère négativement avec la fonction de CSN. Ainsi, j’ai établi un modèle putatif pour expliquer comment TCTP régule la progression du cycle cellulaire via une interférence avec l’activité de deneddylation du CSN, et donc contrôle l’activité des complexes CRLs. Dans la dernière partie de ma thèse, afin de comprendre si le rôle de TCTP est conservé chez les animaux, j'ai par une approche biochimique évaluée la neddylation de CUL1 chez Drosophila melanogaster. Mes données montrent que comme chez Arabidopsis, la fraction déneddylée de CUL1 augmentait dans des larves de drosophile sous-accumulant TCTP, suggérant que ce mécanisme puisse être conservé entre l’Arabette et la drosophile / While plants and animals largely diverge in several major aspects, some biological functions are highly conserved between these kingdoms. During organism development, the correct implementation of organs with unique shape, size and function is the result of coordinated cellular processes as cell proliferation and expansion. Translationally Controlled Tumor Protein (TCTP) is a highly conserved protein among all eukaryotes. TCTP mutation leads to embryo lethality, indicating that it is mandatory for organism development. Moreover, it has been shown that TCTP controls organ growth by regulating the G1/S transition and cell cycle progression both in plants and animals. In animals, the molecular pathways by which TCTP controls cell proliferation are well known. However, in plants, the mechanism implicating TCTP in the control of development and cell cycle is less understood. To better understand how TCTP controls cell proliferation and development in Arabidopsis thaliana, the putative TCTP interactors were identified. Among them, CSN4, a subunit of the COP9 signalosome complex (CSN) known to be involved in the control of CULLINS (CUL) neddylation status and CULLIN-RING ubiquitin ligases (CRLs) activity, was identified. Through their ubiquitination activity, CRL complexes are known to control the accumulation of mains cell cycle regulators as Cyclins or Kip Related Proteins. Thus, during my PhD, I studied the interaction between TCTP and CSN4, in order to evaluate if CSN complex could link TCTP to cell cycle control. I used genetic, cellular and biochemical approaches to demonstrate that TCTP and CSN4 interact in the cytoplasm. Phenotypic characterization of plants and cell cultures down- or overexpressing these genes demonstrated that TCTP and CSN4 interact genetically to control G1/S transition. In order to understand if the interaction between these two proteins could interfere with the CSN complex function, I characterized CUL1 neddylation status in transgenic lines misexpressing TCTP and CSN4. Loss of function of TCTP increases the non-neddylated CUL1 fraction, while overexpression of TCTP increases neddylated CUL1 form. These data show that TCTP interferes with the role of CSN complex in regulating CUL1 neddylation. Accordingly, our data suggest that TCTP controls cell cycle progression via controlling CSN deneddylation activity, and thus influencing CRL activity. In the last part of my PhD, I addressed if this role of TCTP is conserved in animals. I used biochemical approach to evaluate CUL1 neddylation in Drosophila melanogaster downregulated for dTCTP. My data show that Drosophila larvae knockdown for dTCTP also leads to an increase of non-neddylated CUL1 fraction. These data suggest that the mechanism by which TCTP/CSN4 regulate cell cycle, is likely conserved between Arabidopsis and Drosophila