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  • Génomes

    • Vendredi 9 novembre 2018 14:00-15:00 - Michael Holdsworth - University of Nottingham, UK

      When the beginning determines the end : The role of the N-end rule pathway in plant growth and development

      Résumé : Abstract
      The N-end rule pathway represents an ancient conserved component of the Ubiquitin Proteasome System, that also has profound effects on proteostasis. It relates the identity of the amino terminal (Nt-) residue of a protein to its destruction by the UPS. Our recent work uncovered the simple biochemical mechanism that plants use to simultaneously sense oxygen and nitric oxide (NO), through the Cys-Arg/N-end rule pathway [1,2]. The AP2-domain ERFVII transcription factors are the first identified plant substrates of this pathway, with conditional stability based on the oxidation status of amino-terminal Cys, providing a homeostatic response mechanism to changes in oxygen and NO levels. This mechanism is used by plants to measure important ecological cues to protect the stem cell niche and enhance survival [3,4]. I will discuss our current approaches to understand N-end rule pathway regulated plant growth and development.
      Selected recent references
      1. Gibbs et al Nature 2011
      2. Gibbs et al Molecular Cell 2014
      3. Abbas et al Current Biology 2015,
      4. Vicente et al Current Biology 2017
      Contact : GIGLIONE Carmela <carmela.giglione>

      Lieu : Bibliothèque- bâtiment 34 - Campus CNRS de Gif-sur-Yvette


    • Vendredi 30 novembre 2018 11:00-12:00 - Peter Meister - Cell Fate and Nuclear Organization, Institute of Cell Biology, University of Bern, Switzerland

      Polycomb and Notch signaling regulate cell proliferation potential during C. elegans life cycle

      Résumé : Stable cell fate is an essential feature for multicellular organisms in which individual cells achieve specialized functions. The nematode C. elegans is a great model to analyze the determinants of cell fate stability due to its invariant lineage. We present a tractable cell fate challenge system where transdifferentiation is induced by expression of cell-fate specifying transcription factors. We show that wild-type differentiated animals are highly resistant to cell fate challenge. Removal of heterochromatin marks showed marked differences : while the absence of histone 3 lysine 9 methylation (H3K9) had no effect on cell fate stability, Polycomb homolog mes-2 mutants lacking H3K27 methylation terminally arrested larval development. Unexpectedly, transdifferentiation-induced arrest correlated with cell proliferation in many lineages (hyperplasia) and catastrophic mitoses in the seam cells, presumably responsible for larval arrest. Using a candidate RNAi screen to identify genes whose knock-down could rescue the transdifferentiation-induced larval arrest, we show the LIN-12Notch pathway is essential for cell proliferation induction. Notch signaling appears downstream of food-sensing pathways, as dauers and first larval stage diapause animals are highly resistant to cell fate challenge. Our results demonstrate an equilibrium between proliferation versus differentiation regulated by Polycomb and Notch signaling in the soma during the nematode life cycle.

      Lieu : Bibliothèque Bât.34 - Campus Gif-sur-Yvette


  • I2BC

    • Mardi 6 novembre 2018 14:00-15:30 - Jérome Santolini - Département B3S, I2BC

      Docteur CYP et Mister NO

      Résumé : L’an dernier, Pierre Dorlet, le responsable du Laboratoire « Stress Oxydant et Détoxication », est parti vers Marseille pour d’autres aventures. Dans le cadre de l’HCERES, l’I2BC organise un séminaire du LSOD pour valider le changement de chef d’équipe. C’est l’opportunité de rappeler les thèmes de recherche du LSOD, les approches méthodologiques, de revenir sur quelques faits marquants et de présenter les principaux projets de notre équipe pour les années à venir. Ceux-ci s’articulent autour de deux grands axes
      Docteur CYP : François André est devenu un expert mondial dans la modélisation structurale et fonctionnelle des cytochromes P450 (CYPs). Les travaux de Français portent en particulier dans la désorphelinisation de nombreux CYPs humains ou de plantes, et s’inscrivent dans un projet plus vaste d’identification de nouveaux ligands et nouvelles fonctions de cette famille de protéines qui reste à ce jour encore largement inexplorée.
      Mister NO° : Jérôme Santolini travaille depuis plus de vingt ans sur une autre famille d’oxygénases très liée aux CYPs, les NO-Synthases (NOS). Après avoir contribué à l’élucidation du mécanisme moléculaire des NOSs de mammifères, ses projets portent aujourd’hui sur la caractérisation structurale et fonctionnelle de nouvelles familles de NOSs.
      La discussion du séminaire nous permettra d’évoquer également les possibles interactions du LSOD avec l’I2BC dans le cadre de l’évolution de ce nouvel institut.

      Lieu : Auditorium I2BC - Bât.21, Campus Gif sur Yvette


    • Lundi 19 novembre 2018 14:00-15:00 - Sylvie Lautru - Département Microbiologie, I2BC

      Specialized metabolism of Actinobacteria : biosynthesis, regulation and synthetic biology

      Lieu : Auditorium I2BC - Bât. 21, Campus Gif


  • I2BC

    • Lundi 5 novembre 2018 14:00-15:00 - Alexandre GRASSART - Institut PASTEUR, Paris

      From single molecule to tissue : understanding endocytosis mechanisms at its native state

      Résumé : Cells permanently communicate with its environment and mediate information inside the cell through an intricate vesicular trafficking network. At the plasma membrane, receptor-mediated endocytosis is deeply integrated to this cellular logistic and thus play key role in the regulation of cell signaling and homeostasis. My research is focused on understanding the molecular mechanisms and regulatory circuit underlying the assembly of these cellular machineries. To do so, I pioneered an approach based of gene-editing in human cells, live-cell imaging with single molecule resolution and analytical tools to determine the native stoichiometry of proteins during endocytosis in real time. My findings support a model in which endocytosis pathways are governed by two decisional checkpoints. Now I aim to better identify the molecular factors involved in these critical steps and define the regulatory mechanisms involved. A particular effort will be focus on understanding how the physical and cellular microenvironment could interplay with the endocytosis molecular machinery dynamics and determine its impact on intestinal stem cell fate. Toward this goal, I recently developed a biomimetic device recapitulating a 3D organotypic intestinal epithelium barrier interface and the mechanical forces encountered at the organ level. During this presentation, I will present this approach and data demonstrating its physiological relevance. In particular, I tested the capacity of this new model system to recapitulate the infection of Shigella flexneri, an enteroinvasive bacterium whose natural reservoir is exclusively human. In contrast to conventional “flat” in vitro models, I could strikingly observed a level of infection close to clinical data. Thus, this strategy opens new avenues for studying in vitro the biology of human intestinal epithelial cell barrier and its interactions in an environment close to its physiological state.

      Lieu : salle des séminaires - bâtiment 26 - Campus de Gif-sur-Yvette


  • B3S

    • Mardi 13 novembre 2018 14:00-15:00 - Jerome Bonnet - Centre de Biochimie Structurale INSERM/CNRS University of Montpellier

      Engineering synthetic bacterial receptors

      Lieu : Salle Kalogeropoulos - Bât. 400, Campus d’Orsay


  • cytoskeleton club

    • Mardi 13 novembre 2018 11:30-13:00 - Pierrick Le Borgne - Biocil - dpt Biologie Cellulaire - I2BC : Deciphering transition zone ultrastructure and basal body anchoring

      Cytoskeleton club

      Lieu : Bibliothèque - bât. 34


Journée de département

  • Biologie Cellulaire

    • Vendredi 9 novembre 2018 09:00-18:00 -

      6ème journée du département de Biologie Cellulaire

      Résumé :

      Lieu : Domaine de Saint-Paul - Saint-Rémy-les-Chevreuse


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