Les pathogènes neurotropiques représentent une banque d’outils biologique afin de cibler spécifiquement le système nerveux central (SNC), pour son étude mais aussi dans l’optique d’une thérapie. Parmi eux, l’adénovirus canin de type 2 (CAV-2) est un vecteur prometteur pour cibler le SNC. CAR a été principalement étudié en tant que récepteur viral. Cependant, plusieurs études montrent que CAR est essentiel dans le développement du cœur ainsi que du système lymphatique. De manière intéressante, CAR est fortement exprimé pendant le développement du SNC, suggérant un rôle dans l’établissement des réseaux neuronaux. Dans ce travail, nous avons confirmé que CAR est lié aux mécanismes d’endocytoses et au trafic intracellulaire. L’endocytose de CAR est ligand dépendant. La partie intracellulaire de CAR régule son endocytose. Nos données suggèrent que CAR est l’unique récepteur pour CAV-2. Le présent travail de recherche montre aussi que CAR ne semble pas participer à la formation du SNC. En revanche, au niveau du SNC mature, CAR est impliqué dans la plasticité synaptique, dans la neurogénèse adulte et participe à l’homéostasie des synapses, mécanismes impliqués dans les processus mnésiques. / The coxsackievirus and adenovirus receptor (CAR) is a single-pass transmembrane protein belonging to the CTX subfamily of the immunoglobulin superfamily. CAR has been extensively studied as a viral receptor for coxsackie B viruses and some adenoviruses (AdVs). CAR is essential for the development of the cardiovascular and lymphatic system. Interestingly, CAR is highly expressed in the developing brain and has been hypothesized to regulate the establishment of the neuronal networks. In my PhD work, I showed that CAR can be link to the endocytic pathways and intracellular trafficking. CAR endocytosis is ligand-dependent and is regulated by CAR intracellular domain (ICD), suggesting strongly that CAR is most likely the unique receptor for canine adenovirus type 2 (CAV-2). Moreover, we demonstrated that CAR depletion in the developing brain did not significantly perturb brain development. In the healthy adult brain, CAR is relatively abundant and we demonstrated that CAR loss of function affected hippocampal plasticity, adult neurogenesis and synapse homeostasis, which affect cognition.

Chlamydia trachomatis est une bactérie intracellulaire obligatoire pathogène pour l'homme, qui se développe dans un compartiment appelé inclusion. La membrane de l'inclusion constitue une protection contre les défenses de l'hôte, mais limite l'accès aux nutriments. Un élément essentiel pour C. trachomatis est le glucose. Son polymère, le glycogène, est abondant dans le lumen de l'inclusion. Ce travail a eu pour objectif de reconstituer le flux de glucose dans des cellules infectées et d'expliquer l'accumulation du glycogène. En résumé, notre travail démontre que l'accumulation de glycogène dans la lumière de l'inclusion est le résultat de deux processus, l'import de glycogène " brut " de l'hôte par invagination de la membrane de l'inclusion, et la synthèse de novo de glycogène dans le lumen de l'inclusion. Ce dernier implique l'import d'UDP-glucose par un transporteur de la cellule hôte qui est recruté dans la membrane de l'inclusion, et la sécrétion d'enzymes bactériennes dans le lumen de l'inclusion. Ces mécanismes permettent aux bactéries de stocker des molécules énergétique, inaccessibles à l'hôte. / The human pathogen Chlamydia trachomatis is an obligate intracellular bacterium, which develops in a parasitophorous compartment called inclusion. The inclusion membrane serves as a barrier to host defense mechanisms, but limits access to nutrients. One essential nutrient for C. trachomatis is glucose, and its polymer, glycogen, is highly abundant in the inclusion lumen. This work aimed to reconstitute the glucose flow in C. trachomatis infected cells and to understand the mechanisms for glycogen accumulation. In summary, our work demonstrates that glycogen storage in C. trachomatis inclusions is the result of two different strategies, bulk acquisition of host glycogen through invagination of the inclusion membrane, and de novo synthesis of glycogen within the inclusion lumen. The latter mechanism implicates the import of host UDP-glucose through a host transporter that is recruited to the inclusion membrane, and the secretion of bacterial glycogen enzymes into the inclusion lumen. These processes allow the bacteria to build an energy store within the inclusion lumen, out of reach for the host.

Parathyroid hormone (PTH) secretion maintains free-ionised extracellular calcium (Ca2+o) homeostasis under the control of the calcium-sensing receptor (CaR). In humans and dogs, blood acidosis and alkalosis is associated with increased or suppressed PTH secretion respectively. Furthermore, large (1.0 pH unit) changes in extracellular pH (pHo) alter Ca2+o sensitivity of the CaR in CaR-transfected HEK-293 cells (CaR-HEK). Indeed, it has been found in this laboratory that even pathophysiological acidosis (pH 7.2) renders CaR less sensitive to Ca2+o while pathophysiological alkalosis (pH 7.6) increases its Ca2+o sensitivity, both in CaR-HEK and parathyroid cells. If true in vivo, then CaR’s pHo sensitivity might represent a mechanistic link between metabolic acidosis and hyperparathyroidism in ageing and renal disease. However, in acidosis one might speculate that the additional H+ could displace Ca2+ bound to plasma albumin, thus increasing free-Ca2+ concentration and so compensating for the decreased CaR responsiveness. Therefore, I first demonstrated that a physiologically-relevant concentration of albumin (5% w/v) failed to overcome the inhibitory effect of pH 7.2 or stimulatory effect of pH 7.6 on CaR-induced intracellular Ca2+ (Ca2+i) mobilisation. Determining the molecular basis of CaR pHo sensitivity would help explain cationic activation of CaR and permit the generation of experimental CaR models that specifically lack pHo sensitivity. With extracellular histidine and free cysteine residues the most likely candidates for pHo sensing (given their sidechains’ pK values), all 17 such CaR residues were mutated to non-ionisable residues. However, none of the resulting CaR mutants exhibited significantly decreased CaR pHo sensitivity. Even co-mutation of the two residues whose individual mutation appeared to elicit modest reductions (CaRH429V and CaRH495V) failed to exhibit any change in CaR pHo sensitivity. I conclude therefore, that neither extracellular histidine nor free cysteine residues account for CaR pHo sensitivity. Next, it is known that cytosolic cAMP drives PTH secretion in vivo and that cAMP potentiates Ca2+o-induced Ca2+i mobilisation in CaR-HEK cells. Given the physiological importance of tightly controlled PTH secretion and Ca2+o homeostasis, here I investigated the influence of cAMP on CaR signalling in CaR-HEK cells. Agents that increase cytosolic cAMP levels such as forskolin and isoproterenol potentiated Ca2+o-induced Ca2+i mobilisation and lowered the Ca2+o threshold for Ca2+i mobilisation. Indeed, forskolin lowered the EC50 for Ca2+o on CaR (2.3 ± 0.1 vs. 3.0 ± 0.1 mM control, P<0.001). Forskolin also potentiated CaR-induced ERK phosphorylation; however protein kinase A activation appeared uninvolved in any of these effects. Pertussis toxin, used to block CaR-induced suppression of cAMP accumulation, also lowered the Ca2+o threshold for Ca2+i mobilisation though appeared to do so by increasing efficacy (Emax). Furthermore, mutation of the CaR’s two putative PKA consensus sequences (CaRS899 and CaRS900) to a non-phosphorylatable residue (alanine) failed to alter the potency of Ca2+o for CaR or attenuate the forskolin response. In contrast, phosphomimetic mutation of CaRS899 (to aspartate) did increase CaR sensitivity to Ca2+o. Together this suggests that PKA-mediated CaRS899 phosphorylation could potentiate CaR activity but that this does not occur following Ca2+o treatment in CaR-HEK cells. Together, these data show that cAMP regulates the Ca2+o threshold for Ca2+i mobilisation, thus helping to explain differential efficacy between CaR downstream signals. If true in vivo, this could help explain how multiple physiological signal inputs may be integrated in parathyroid cells.

Macrophages are professional phagocytes that efficiently clear microbes, dying cells, and debris. Nonetheless, some pathogenic bacteria and parasites can subvert the macrophage phagosome into a vacuolar replicative niche. Exogenous macrophage activation by the cytokine interferon gamma (IFNγ) tips the equilibrium toward pathogen restriction, host survival, and subsequent adaptive immune responses. The relevance of IFNγ-induced immunity to human health has been demonstrated in patients with genetic defects in IFNγ signaling, who are profoundly susceptible to vacuolar pathogens such as Mycobacterium tuberculosis. Still, much remains to be discovered about IFNγ effector functions, and about their co-regulation by signaling downstream of the many innate immune sensors in macrophages. First, we asked whether IFNγ-induced vesicle trafficking mechanisms affect the maturation of phagosomes containing the bacterium Legionella pneumophila, the causative agent of Legionnaire's disease. We used functional genetic screening to discover candidate genes involved. From 380 genes in a curated vesicle trafficking-related set, 15 were selected as candidate IFNγ pathway members by RNAi screening in cell line and primary mouse macrophages. Functional validation of top candidates was inconclusive, but revealed potential roles for membrane tetraspanins and the AP3 complex in IFNγ-induced microbial restriction. Our second goal was to determine whether innate immune sensing affects IFNγ-induced bacterial restriction. Using macrophages from mice deficient in key elements of innate immune sensing pathways, we discovered that the antiviral transcription factor IRF3, which functions downstream of many nucleic acid sensing pathways, suppresses IFNγ-induced restriction of L. pneumophila and the protozoan parasite Trypanosoma cruzi. While activated IRF3 localizes to the nuclei in resting macrophages infected with L. pneumophila, it is mostly excluded from nuclei in macrophages activated with IFNγ prior to infection. This suggests a cascade of suppression in which IFNγ responses inhibit IRF3 activation, but residual IRF3 activity antagonizes IFNγ effectors. IRF3-mediated inhibition of IFNγ-inducible nitric oxide synthase was partially, but incompletely responsible for the phenotype observed; further candidate effectors were identified by gene expression profiling. We speculate that antagonism between IFNγ and IRF3-mediated mechanisms may facilitate a balance of vacuolar pathogen immunity with viral defense, or with protection of tissue damage by nitric oxide and other IFNγ-dependent responses.

La Maladie d’Alzheimer (MA) est un des challenges sanitaires les plus importants du XXIème siècle. En effet, elle touche 35,6 millions de personnes en 2010, et en atteindra probablement quatre fois plus en 2050.Cependant, peu d’éléments sont à ce jour connus concernant les mécanismes de toxicité de cette maladie. Il semble néanmoins acquis que l’agrégation du peptide amyloïde Aβ est l’élément déclenchant une cascade d’événements cellulaires aboutissant à trois types de lésions : les dégénérescences neurofibrillaires, les plaques amyloïdes et une atrophie corticale, révélatrice d’une importante mort neuronale.Différents modèles transgéniques d’étude de la toxicité du peptide Aβ ont été créés au cours des vingt dernières années. Cependant, aucun modèle de levure n’a encore vu le jour, alors que cet organisme est utilisé depuis de nombreuses années pour l’étude des protéines amyloïdes.J’ai donc cherché à créer ce modèle de toxicité au cours de ma thèse. L’adressage d’une protéine de fusion Aβ-GFP à la voie de sécrétion permet de rendre son expression toxique chez la levure. J’ai démontré que le trafic intracellulaire était un élément important pour la génération d’espèces toxiques. Les orthologues de PICALM, facteur de prédisposition à la MA, sont impliqués dans la toxicité, montrant une conservation des mécanismes de toxicité avec l’Homme. Les constructions semblent avoir la capacité de traverser les membranes afin d’atteindre des cibles cellulaires comme la mitochondrie.Le modèle ainsi construit nous permettra de mettre en place une étude de la relation entre la structure et la toxicité du peptide Aβ et mieux comprendre les mécanismes cellulaires régissant la MA. / Alzheimer’s Disease (AD) is one of the most important sanitary challenges of the XXIst century. Indeed, 35.6 million people are affected in 2010, and there will be probably four times more in 2050. However, little is known about the mechanisms of toxicity of this disease. Nevertheless, it seems that aggregation of the Aβ peptide is the triggering factor of a cascade of cellular events that leads to three characteristic lesions: neurofibrillary tangles, amyloid plaques and a cortical atrophy, revealing an important neuronal death. Different transgenic models for the study of the Aβ peptide toxicity have been created during the past twenty years. However, no yeast model has yet seen the light of day, whereas this organism is used for several years to study amyloid proteins.Therefore I worked to create this model during my thesis. Addressing an Aβ-GFP fusion to the secretory pathway enable this construction to become toxic in yeast. I proved intracellular pathways are important for generation of toxic species. PICALM orthologs, an AD predisposing factor, are involved in toxicity, showing conservation in the mechanisms of toxicity between yeast and man. The constructions seem to be able to cross membranes and reach cytoplasmic targets as mitochondria.Thus, this model will allow us to set a study of the relationship between structure and toxicity of the Aβ peptide and better understand the cellular mechanisms governing AD

A oligopeptidase neurolina (E.C.3.4.24.16; nln ) foi identificado pela primeira vez em membranas sinápticas de cérebro de ratos como sendo capaz de participar no metabolismo de peptídeos bioativos, como neurotensina e bradicinina. Recentemente, foi sugerido que a ausência de Nln pode melhorar a sensibilidade a insulina. Aqui, nós mostrado que camundongos knockout para Nln (KO) são mais tolrerantes à glicose, sensíveis à insulina e apresentam maior gliconeogênese. Os animais KO apresentou um aumento na expressão de mRNA de vários genes relacionados com a gliconeogênese no fígado. A semiquantificação de peptídeos intracelulares revelou um aumento em peptídeos intracelulares específicos no gastrocnêmio e tecido adiposo epididimal, que estão envolvidos com o aumento da tolerância a glicose e maior sensibilidade à insulina nos animais KO. Esses resultados sugerem fortemente a nova possibilidade de que Nln é uma enzima chave no metabolismo energético e pode ser um novo alvo terapêutico para melhorar a captação de glicose e sensibilidade a insulina. / The oligopeptidase neurolysin (EC 3.4.24.16; Nln) was first identified in rat brain synaptic membranes and shown to ubiquitously participate in the catabolism of bioactive peptides such as neurotensin and bradykinin. Recently, it was suggested that Nln reduction could improve insulin sensitivity. Here, we have shown that Nln knockout mice (KO) have increased glucose tolerance, insulin sensitivity and gluconeogenesis. KO mice have increased liver mRNA for several genes related to gluconeogenesis. Isotopic label semi-quantitative peptidomic analysis suggests increase in specific intracellular peptides in gastrocnemius and epididymal adipose tissue, which likely is involved with the increased glucose tolerance and insulin sensitivity in the KO mice. These results suggest the exciting new possibility that Nln is a key enzyme for energy metabolism and could be a novel therapeutic target to improve glucose uptake and insulin sensitivity.

Peptídeos intracelulares são constantemente produzidos pelo sistema ubiquitina proteassomo e muitos são provavelmente funcionais. Aqui, um nonapeptídio derivado da ciclina-D2, específica da transição G1/S, chamado \"pep5\" mostrou um aumento específico durante a fase S do ciclo celular em células HeLa. O pep5 (50-100 &mu;M) induziu a morte celular em células HeLa e em várias outras células tumorais, mas isso só ocorreu quando o pep5 foi sintetizado acoplado ao peptídeo penetrador de células (pep5-cpp). In vivo, o pep5-cpp reduziu o volume do glioblastoma C6 de ratos Wistar em cerca de 50%. A acetilação reduziu a potência do pep5-cpp, enquanto substituições Leu-Ala aboliram totalmente a atividade deste peptídeo. Os resultados de caracterização inicial do mecanismo de morte celular indizida pelo pep5 incluem ativação de caspases 3/7 e 9, inibição da fosforilação Akt2 e inibição da atividade do proteassomo. Esses dados colaboram com a hipótese da função de peptídeos intracelulares na sinalização. / Intracellular peptides are constantly produced by the ubiquitinproteasome system and many are probably functional. Here, a nonapeptide of G1/S-specific cyclin-D2 named pep5 showed a specific increase during the S phase of HeLa cell cycle. Pep5 (50-100 &mu;M) induced cell death in HeLa and in several other tumor cells, only when it was fused to a cell penetrating peptide (pep5-cpp). In vivo, the pep5-cpp reduced the volume of the rat C6 glioblastoma by almost 50%. Acetylation reduced the potency of the pep5-cpp while Leu-Ala substitutions totally abolished the pep5 activity. Findings from the initial characterization of the cell death mechanism of pep5 include caspase 3/7 and 9 activation, inhibition of Akt2 phosphorylation and inhibition of proteasome activity. These data further support the intracellular function of peptides.

Our previous work in yeast has demonstrated that overexpression of FPR1, and others FKBP immunophilins, conferred tolerance to weak organic acids such as acetic and sorbic acid. FK506 binding proteins (FKBP) where originally identified as the cellular targets of the immunosuppressant drugs rapamycin an FK506. FKBPs are peptidyl-prolyl cis-trans isomerases (PPase EC 5.1.2.8) that catalize the isomerization of peptidyl prolyl bonds between cis and trans configuration. FKBP are ubiquitous proteins that can be found either as a single catalytic proteins or being part of more complex proteins. To assess the implication of FKBP proteins in weak acid tolerance in plants we have generated lines of Arabidopsis thaliana overexpressing two different proteins: yeast FPR1 an Arabidopsis FKBP65 (ROF2). We isolated knock-out mutant rof2 and rof1 from T-DNA mutant seeds collection of Salk institute. Finally we crossed the single mutants to get the double mutant rof1 x rof2. In presence of acetic acid transgenic lines overexpressing any of these genes grew better than wild type plant. On the other hand an AtFKBP65 loss-of-function mutant line showed weak acid sensitivity. We Observed a similar behavior in presence of toxic cations (Norspermidine, Hygromycim B) suggesting a role in K+ transport and we have got the confirmation with the growth al low levels of K+. We excluded the direct participation of plasma membrane ATPase because its activity in rof2 knock out mutant is higher. Furthermore ROF2 overexpression lines show a lower activity than wild-type. With 35S:: ROF2-GFP construction it was possible to see a cytosolic and nuclear cellular distribution that in presence of weak acid condition change: the ROF"-GFP leave the nuclear region. In absence of stress we have observed a gain of apical dominance in 35S::AtFKBP65 mutants and its loss in FKBP65 knock-out line. The roots of AtFKBP65 knock-out mutants have reduced number of lateral roots and exogenous application of IAA was abl / Bissoli, G. (2013). Prolyl isomerases are important determinants of intracellular pH homeostasis in Arabidopsis thaliana [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/27596 / Palancia

La maladie de Huntington (MH) est une maladie neurodégénérative avec une transmission dominante, qui entraîne la mort dans les 15 à 20 ans suivant les premiers signes pathologiques. Le gène muté dans la MH contient une répétition de trinucléotide CAG instable qui code pour une expansion de polyglutamine (polyQ) dans la protéine huntingtine (HTT). Lorsque le gène code pour une protéine avec plus de 35 glutamines, il déclenche un dysfonction puis une mort neuronale notamment dans le striatum et le cortex, entrainant l'apparition de symptômes cognitifs, psychiatriques et moteurs. HTT est exprimée dans de nombreux tissus et est impliquée dans diverses fonctions cellulaires. Il est admis que dans la MH, l'expansion polyQ conduit à un gain de nouvelles fonctions toxiques, mais également à une perte des fonctions neuroprotectrices de HTT sauvage. Avant même l'apparition des premiers symptômes, des dysfonctions existent au sein du réseau neuronal corticostriatal. Cependant, les études in vivo des dysfonctions précoces au sein de ce réseau sont techniquement difficiles à l’échelle cellulaire.Le premier enjeu de ma thèse a été de reconstituer et de caractériser in vitro le réseau corticostriatal. Pour cela nous avons utilisé une plateforme microfluidique, compatible avec de la vidéomicroscopie haute résolution, dans laquelle chaque compartiment est identifié et où la progression de la croissance axonale à la formation des synapses est régulée. Nous avons observé des défauts majeurs au sein des différents compartiments du réseau corticostriatal, de la dynamique présynaptique à des défauts de structure et de transmission synaptiques, ainsi que des dysfonctions du trafic et des voies de signalisation post-synaptique. De manière intéressante, nous avons montré que le statut génétique du compartiment présynaptique était nécessaire et suffisant pour altérer ou restaurer le réseau corticostriatal.Le second aspect de ma thèse a été d’étudier la dynamique intracellulaire, depuis le réticulum endoplasmique jusqu’au compartiment final, au sein de cellules modèles de la MH. Pour cela nous avons utilisés le système RUSH (Retention Using Selective Hooks) couplé à une molécule utilisant la voie standard de biosynthèse des protéines. Au sein de cellules modèles de la MH, la dynamique intracellulaire est perturbée. L’utilisation de molécules inhibitrices d’une classe d’enzyme au sein de cellules modèles de la MH, est capable de restaurer une dynamique intracellulaire. En particulier, grâce au système microfluidique, nous avons montré qu’une molécule a la capacité de restaurer un réseau corticostriatal sauvage. Les études pharmacologiques de passage ont montré que cette molécule a un haut pouvoir de passage de la barrière hémato encéphalique. Le traitement pendant un mois de souris modèles de la MH et l’analyse de leur coordination motrice et de leur état anxiodépressif suggère que cette molécule est capable d’améliorer les symptômes chez les souris MH.Ces travaux ont permis de mettre en évidence 1/ l’importance du cortex comme région d’intérêt thérapeutique dans la MH, et 2/ le trafic de protéines comme une nouvelle cible thérapeutique. / Huntington Disease (HD) is a mid-life onset inherited neurodegenerative disorder that leads to death within 15 to 20 years after appearance of the first symptoms. The defective gene in HD contains an unstable trinuocleotide CAG repeat which encodes for a polyglutamine stretch (polyQ) in the huntingtin (HTT) protein. When the number of glutamines coded by the gene exceeds 35 repeats, it triggers neuronal dysfunction and death, affecting in particular the striatum and the cortex, causing cognitive, psychiatric, and motor symptoms. HTT is widely expressed and it is involved in numerous functions. In HD, it is accepted that, the polyQ strech leads to a gain of toxic functions, and converselyto a loss of neuroprotective functions of wild-type HTT. Long before the appearance of the first symptoms, dysfunctions exist within the corticostriatal neuronal network. However, in vivo studies of early cell dysfunction in this network are technically difficult, especially at the subcellular resolution.The first objective of my thesis was to reconstitute and characterize the corticostriatal network in vitro. We used a microfluidic device in which each neuronal compartment is identified and in which the progression from axonal growth to synapse regulation is controlled. We observed major defects in the different compartments of the corticostriatal circuit, from presynaptic dynamics to synaptic structure and transmission and to postsynaptic traffic and signaling. Importantly, the genetic status of the presynaptic compartment was necessary and sufficient to alter or restore the circuit.The second aspect of my thesis was to study the intracellular dynamics, from the endoplasmic reticulum to the final compartment, in cellular models of HD. For this we used the RUSH system (Retention Using Selective Hooks) coupled to a molecule using the standard pathway of protein biosynthesis. In cellular models of HD, intracellular dynamics are disrupted. We found that molecules targeting enzyme protein trafficking restore intracellular dynamics in HD cells. In particular, thanks to the microfluidic system, we showed that a given molecule has the capacity to restore a HD mutant corticostriatal network. Pharmacological studies showed that this molecule has a high power of passage of the blood brain barrier. One month treatment of HD mouse models and their behavioral tests for motor and anxiety-depressive symptoms suggest that the molecule is able to ameliorate symptoms.These studies made it possible to highlight 1 / the importance of the cortex as a key region of therapeutic interest in HD, and 2 / protein trafficking as a new therapeutic target in HD.

La migration des cellules est nécessaire au cours du développement. Chez l’adulte, elle contribue au renouvellement des tissus, à la cicatrisation et à la circulation des cellules immunitaires. Les cellules cancéreuses acquièrent des capacités de migration qui échappent aux mécanismes normaux de régulation. Elles peuvent ainsi envahir les tissus environnants et, éventuellement, former des métastases. Les astrocytes représentent une majorité de cellules gliales du système nerveux central. Ils migrent en réponse à des facteurs inflammatoires et interviennent ainsi dans la cicatrisation et la régénération des tissus lésés. Les astrocytes peuvent être à l’origine de tumeurs appelées gliomes qui représentent la majorité des tumeurs cérébrales primaires. Les formes les plus agressives, appelées glioblastomes, sont des tumeurs extrêmement invasives, ce qui les rend particulièrement difficiles à traiter. Les microtubules jouent un role crucial dans la migration des astrocytes et des cellules de gliomes (Etienne-Manneville, 2013a). Au cours de la migration, le réseau de microtubules est totalement réorganisé pour permettre la polarisation de la cellule. Formés par association de dimères de tubuline, leur régulation intervient de multiples manières comme par exemple au niveau de leur dynamique de polymérisation à la périphérie de leurs interactions avec les composants cellulaires ou par leurs modifications post-traductionnelles (Etienne- Manneville, 2010). En effet, les dimères de tubulines polymérisées, inclues dans les microtubules, peuvent être, entre autres, détyrosinées, acétylées, mono ou poly-glutamylées, et mono ou poly-glycylées (Janke and Chloë Bulinski, 2011). Durant la migration cellulaire, ces modifications post-traductionnelles peuvent notamment jouer un rôle dans la régulation du trafic intracellulaire. L’objectif majeur de mon projet de thèse est d’étudier les mécanismesIii de régulation des microtubules au cours de la migration des astrocytes normaux et tumoraux, et plus particulièrement le rôle des modifications post-traductionnelles de la tubuline. Je me suis focalisée sur trois principales modifications post-traductionnelles des microtubules durant la migration : la polyglutamylation, la détyrosination et l’acétylation. En premier lieu, j’ai étudié le rôle potentiel de la polyglutamylation dans la mise en place de la polarité cellulaire chez les astrocytes. Je n’ai pas observé d’effet de cette modification durant la migration… / The migration of cells is necessary during the development. At the adult, she contributes to the renewal of fabrics, to the healing and to the traffic of immune cells. Cancer cells acquire capacities of migration which escape the normal mechanisms of regulation...