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Département Biologie des Génomes

par Clubs génome, EQYY - publié le , mis à jour le


  • Vendredi 21 juin 11:00-12:00 - Lori A. PILE - Department of Biological Sciences, Wayne State University, Detroit, Michigan, USA

    Determination of gene regulatory and metabolic networks by an essential histone modifying complex

    Résumé : Regulation of the spatial and temporal patterns of gene expression is central to every aspect of organismal development, normal physiological function and is directly linked to numerous diseases. Histone modifying enzymes that add or remove histone marks regulate chromatin structure to promote or repress gene activity. Among the key complexes that regulate the epigenetic signatures on histones is the SIN3 histone modifying complex, which contains both a deacetylase and a demethylase enzyme. How these factors coordinately regulate expression of specific gene sets to control cell proliferation and developmental transitions is largely unknown. Through analysis of chromosomal localization patterns and gene expression profiles, we determined genome-wide functional regulatory activity of the two major isoforms of Drosophila SIN3. Because we found that both isoforms regulate genes encoding key metabolic enzymes, we next identified metabolites controlled by SIN3. These experiments have uncovered SIN3 controlled gene and metabolic networks linking epigenetic regulation by SIN3 to central carbon metabolism necessary for cellular energy production.

    Lieu : Salle des séminaires - bâtiment 26 - campus de Gif-sur-Yvette

  • Vendredi 28 juin 10:00-11:00 - Yves GAUDIN - I2BC

    Negri bodies are viral factories with properties of liquid organelles

    Résumé : Replication and assembly of many viruses occur in viral factories which are specialized intracellular compartments formed during viral infection. For rabies virus, those viral factories are called Negri bodies (NBs). NBs are cytoplasmic inclusion bodies in which viral RNAs (mRNAs as well as genomic and antigenomic RNAs) are synthesized. NBs are spherical, they can fuse together and can reversibly deform when encountering a physical barrier. All these characteristics are similar to those of eukaryotic membrane-less liquid organelles which contribute to the compartmentalization of the cell interior. Indeed, the liquid nature of NBs has been confirmed by FRAP experiments. The co-expression of rabies virus nucleoprotein N and phosphoprotein P is sufficient to induce the formation of cytoplasmic inclusions recapitulating NBs properties. Remarkably, P and N have features similar to those of cellular proteins involved in liquid organelles formation : N is an RNA binding protein and P contains intrinsically disordered domains. An overview of the literature indicates that formation of liquid viral factories by phase separation is probably common among Mononegavirales. This allows specific recruitment and concentration of viral proteins. Finally, as virus-associated molecular patterns recognized by cellular sensors of RNA virus replication are probably essentially present in the viral factory, there should be a subtle interplay (which remains to be characterized) between those liquid structures and the cellular proteins which trigger the innate immune response.

    Lieu : Bibliothèque - bâtiment 34 - campus de Gif-sur-Yvette

  • Vendredi 5 juillet 11:00-12:00 - Julien PONTIS - Laboratory of virology and genetics Ecole Polytechnique Fédérale de Lausanne (EPFL), Switzerland

    Hominoid-specific regulatory sequences and their controllers shape human genome regulation

    Résumé : Transposable elements (TEs) are key to the evolutionary turnover of regulatory sequences. How they can play such an essential role in spite of their genotoxic potential is unknown. Here, we propose that Krüppel-Associated Box (KRAB)-containing zinc finger proteins (KZFPs) control the timely and pleiotropic engagement of TE-derived cis-regulators of transcription. We first observed that evolutionary recent TEs of the SVA, HERVK and HERVH subgroups are major contributors to chromatin opening during human embryonic genome activation and act as Krüppel-Like Factors (KLFs)-stimulated enhancers in naïve human embryonic stem cells. We then found that KZFPs of corresponding evolutionary ages are simultaneously induced and repress the transcriptional activity of these TEs. We finally determined that the same KZFP-controlled TE-based enhancers later serve as developmental and tissue-specific regulators of gene expression. Thus, by taming the transcriptional impact of TEs during early embryogenesis, KZFPs allow for their genome-wide incorporation into transcriptional networks, thereby contributing to the species-specificity of human genome regulation.

    Lieu : Salle des séminaires - bâtiment 26 - campus de Gif-sur-Yvette

  • Mardi 10 septembre 11:00-12:00 - Céline VALLOT - Institut Curie, Paris

    Séminaire Céline VALLOT

    Lieu : Salle des séminaires - bâtiment 26 - campus de Gif-sur-Yvette

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