66 research outputs found

    Involvement of the endoplasmic reticulum mediator IRE1α in the DNA repair by Homologous Recombination

    No full text
    Le maintien de l’intĂ©gritĂ© de l’ADN et des protĂ©ines est un processus essentiel pour la cellule. Il dĂ©pend principalement de la rĂ©ponse aux dommages Ă  l’ADN (DNA Damage Response, DDR) et de la rĂ©ponse UPR (unfolded protein response). La DDR permet de dĂ©tecter et de rĂ©parer les dommages Ă  l’ADN tandis que l’UPR maintient l’homĂ©ostasie des protĂ©ines. Des perturbations dans l’intĂ©gritĂ© gĂ©nomique ou l’homĂ©ostasie protĂ©ique sont impliquĂ©es dans de nombreuses maladies dont des cancers. Toutefois, l’interaction entre la DDR et l’UPR est trĂšs peu Ă©tudiĂ©e. Seules quelques Ă©tudes suggĂšrent l’existence de liens entre la DDR et l’UPR, majoritairement aprĂšs des cassures double brin (DB) de l’ADN, et impliquent en particulier IRE1α, un acteur majeur de l’UPR. Le travail de ma thĂšse a donc consistĂ© Ă  dĂ©terminer le rĂŽle d’IRE1α dans la DDR. Nos rĂ©sultats rĂ©vĂšlent l’implication d’IRE1α dans une voie de rĂ©paration de l’ADN aprĂšs des cassures DB : la recombinaison homologue (HR). Étonnamment, seule la sous-expression d’IRE1α, mais pas l’inhibition de son activitĂ© ribonuclĂ©asique, influe sur le taux de rĂ©paration par HR. La sous-expression d’IRE1α induit Ă©galement une augmentation du taux de phosphorylation d’H2AX, un marqueur des cassures DB de l’ADN. L’analyse du mĂ©canisme d’action d’IRE1α sur la HR a rĂ©vĂ©lĂ© un impact d’IRE1α sur les phosphorylations, ainsi que sur sa prĂ©sence aux cassures DB, d’une protĂ©ine clĂ© de la HR : RPA. De plus, nos travaux ont permis de dĂ©terminer que le rĂŽle d’IRE1α dans la HR dĂ©pendait de son domaine linker. Nous avons finalement montrĂ© que l’interaction entre la rĂ©ponse UPR et la DDR n’est pas restreinte Ă  IRE1α mais implique Ă©galement les deux autres mĂ©diateurs de l’UPR, i.e. ATF6 et PERK, qui jouent des rĂŽles distincts dans la DDR. Les rĂ©sultats obtenus rĂ©vĂšlent un rĂŽle d’IRE1α, dĂ©pendant de RPA et du domaine linker d’IRE1α, dans la rĂ©paration de l’ADN par HR et ouvrent ainsi la voie Ă  de nouvelles pistes thĂ©rapeutiques pour augmenter l’efficacitĂ© des chimiothĂ©rapies anticancĂ©reuses basĂ©es sur un stress gĂ©notoxique.Maintaining DNA and protein integrity is a critical process for the cell. It depends mainly on two stress response mechanisms: the DNA Damage Response (DDR) and the unfolded protein response (UPR). The DDR enables the cell to detect and repair DNA damage while the UPR maintains protein homeostasis. Disruption of genomic integrity or protein homeostasis may lead to various disorders including cancer. Nonetheless, DDR and UPR interaction is not much studied. Only a few studies suggest the existence of putative links between DDR and UPR, mainly after DNA double-strand breaks (DSB), and these links notably involves IRE1α, a major mediator of UPR. Hence, my PhD work consisted in the determination of the role of IRE1α in the DDR. Our results revealed the involvement of IRE1α in the DDR pathway after DNA DSB called the homologous recombination (HR) pathway. Surprisingly, only IRE1α downregulation, but not the inhibition of its ribonuclease activity, affects the level of repair by HR. IRE1α downregulation leads to an increase in H2AX phosphorylation level that is a hallmark of DNA DSB. The analysis of IRE1α’s pathway on HR revealed an impact of IRE1α on the different phosphorylation marks, as well as on the presence to the DSB, of a key protein of the HR: RPA. In addition, our study identified that the role of IRE1α in the HR depends on its linker domain. We finally showed that the interaction between the UPR and the DDR is not only limited to IRE1α but also to the two other UPR transducers, i.e. ATF6 and PERK. Hence, all these results uncovered a new role for IRE1α, in an RPA and IRE1α’s linker-dependent manner, in the DNA repair by HR. This discovery thereby paves the way for new therapeutic approaches that aim at increasing the efficiency of genotoxic stress-based cancer chemotherapy

    Sociologie de la décentralisation théùtrale

    No full text
    PARIS3-BU (751052102) / SudocPARIS-Fondation MSH (751062301) / SudocSudocFranceF

    Focus-ING on DNA Integrity Implication of ING Proteins in Cell Cycle Regulation and DNA Repair Modulation

    No full text
    International audienceThe ING family of tumor suppressor genes is composed of five members (ING1-5) involved in cell cycle regulation, DNA damage response, apoptosis and senescence. All ING proteins belong to various HAT or HDAC complexes and participate in chromatin remodeling that is essential for genomic stability and signaling pathways. The gatekeeper functions of the INGs are well described by their role in the negative regulation of the cell cycle, notably by modulating the stability of p53 or the p300 HAT activity. However, the caretaker functions are described only for ING1, ING2 and ING3. This is due to their involvement in DNA repair such as ING1 that participates not only in NERs after UV-induced damage, but also in DSB repair in which ING2 and ING3 are required for accumulation of ATM, 53BP1 and BRCA1 near the lesion and for the subsequent repair. This review summarizes evidence of the critical roles of ING proteins in cell cycle regulation and DNA repair to maintain genomic stability

    Theaterfahrt ou comment j'ai mange la guerreLa guerre ne sera pas longue – Die Gefallenen

    No full text
    Genèse et parcours d’un spectacle lié à la commémoration de la Première Guerre mondiale – Entre la France et l’Allemagn

    La Guerre ne sera pas longue / Die Gefallenen. En tournĂ©e Ă  SaarbrĂŒcken

    No full text
    Grandewelt avait décidé de se retrouver pour quelques jours de vacances. Après avoir passé en revue toutes les régions de France et d'Allemagne, de Suisse et d'Autriche, la Belgique et le Luxembourg, notre choix s'était fixé sur Sarrebruck

    Recombination in Enteroviruses, a Multi-Step Modular Evolutionary Process

    Get PDF
    International audienceRNA recombination is a major driving force in the evolution and genetic architecture shaping of enteroviruses. In particular, intertypic recombination is implicated in the emergence of most pathogenic circulating vaccine-derived polioviruses, which have caused numerous outbreaks of paralytic poliomyelitis worldwide. Recent experimental studies that relied on recombination cellular systems mimicking natural genetic exchanges between enteroviruses provided new insights into the molecular mechanisms of enterovirus recombination and enabled to define a new model of genetic plasticity for enteroviruses. Homologous intertypic recombinant enteroviruses that were observed in nature would be the final products of a multi-step process, during which precursor nonhomologous recombinant genomes are generated through an initial inter-genomic RNA recombination event and can then evolve into a diversity of fitter homologous recombinant genomes over subsequent intra-genomic rearrangements. Moreover, these experimental studies demonstrated that the enterovirus genome could be defined as a combination of genomic modules that can be preferentially exchanged through recombination, and enabled defining the boundaries of these recombination modules. These results provided the first experimental evidence supporting the theoretical model of enterovirus modular evolution previously elaborated from phylogenetic studies of circulating enterovirus strains. This review summarizes our current knowledge regarding the mechanisms of recombination in enteroviruses and presents a new evolutionary process that may apply to other RNA viruse

    Nomenclature et classification des entérovirus : quelle histoire !

    No full text
    International audienceDepuis l’identification des premiers entĂ©rovirus, la classification et la nomenclature de ces virus ont Ă©tĂ© remaniĂ©es Ă  de nombreuses reprises. Le fondement mĂȘme de la classification a Ă©tĂ© modifiĂ© au cours des annĂ©es 2000 lorsque les critĂšres gĂ©nĂ©tiques ont supplantĂ© les critĂšres sĂ©rologiques pour l’identification et la classification des entĂ©rovirus. Fruit de ces remaniements, la classification et la nomenclature actuelles sont souvent assez dĂ©routantes pour l’étudiant, le chercheur ou le praticien qui s’intĂ©resse pour la premiĂšre fois Ă  ces virus ; coxsackievirus A et B cĂŽtoient echovirus et poliovirus au sein de diffĂ©rentes espĂšces tandis que, de façon peu intuitive au regard de l’étymologie, les rhinovirus appartiennent dĂ©sormais au genre Enterovirus. Cette revue a pour but de prĂ©senter un aperçu historique des mĂ©thodes et des concepts qui ont Ă©tĂ© utilisĂ©s pour Ă©laborer les classifications successives de ces virus et des dĂ©couvertes qui ont conduit Ă  les rĂ©former. Souvent subtiles, parfois profondes, les modifications apportĂ©es au cours du temps retracent l’histoire de nos connaissances concernant les entĂ©rovirus et celle de notre comprĂ©hension de la diversitĂ© qu’ils prĂ©sentent ; en creux, elles rĂ©vĂšlent surtout notre ignorance

    Small bowel entrapment and ureteropelvic junction disruption associated with L3 Chance fracture-dislocation

    No full text
    Paediatric Chance fracture are rare lesions but often associated with abdominal injuries. We herein present the case of a seven years old patient who sustained an entrapment of small bowel and an ureteropelvic disruption associated with a Chance fracture and spine dislocation following a traffic accident. Initial X-rays and computed tomographic (CT) scan showed a Chance fracture with dislocation of L3 vertebra, with an incarceration of a small bowel loop in the spinal canal and a complete section of the left lumbar ureter. Paraplegia was noticed on the initial neurological examination. A posterior L2-L4 osteosynthesis was performed firstly. In a second time she underwent a sus umbilical laparotomy to release the incarcerated jejunum loop in the spinal canal. An end-to-end anastomosis was performed on a JJ probe to suture the left injured ureter. One month after the traumatism, she started to complain of severe headaches related to a leakage of cerebrospinalis fluid. Three months after the traumatism there was a clear regression of the leakage. One year after the trauma, an anterior intervertebral fusion was done. At final follow-up, no neurologic recovery was noticed. In case of Chance fracture, all physicians should think about abdominal injuries even if the patient is asymptomatic. Initial abdominal CT scan and magnetic resonance imaging provide in such case crucial info for management of the spine and the associated lesions
    • 

    corecore