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Département Biologie des Génomes

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


  • Vendredi 20 septembre 11:00-12:00 - Christian MUCHARDT - Institut Pasteur, Paris

    Regulation of transcription initiation and mRNA maturation by silencing machineries

    Résumé : Machineries imposing long-term transcriptional repression – or transcriptional gene silencing – are essential to prevent expression of repeated and potentially mobile DNA elements, and to ensure the timely and robust transcriptional repression of genes involved in cell differentiation and development. Yet, silencing machineries also participate in transcriptional regulation of inducible genes. In particular, many genes involved in innate immune defense are regulated by members of the HP1 family, keeping them in check in the absence of stimulation, but also regulating their alternative splicing while they are expressed. These mechanisms will be discussed in the context of autoimmune diseases and ageing.

    Contact : BETERMIER Mireille (Mireille.BETERMIER

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

  • Vendredi 27 septembre 11:00-12:00 - Frederic FROTTIN - Max Planck Institute of Biochemistry, D-82152 Martinsried, Germany

    Phasing-in protein quality control in the nucleus : the nucleolus is a phase-separated protein quality control compartment with novel chaperone-like properties.

    Résumé : Protein quality control in the nucleus is not well understood. The nucleus contains several non-membrane bound subcompartments forming liquid-like condensates. The largest of these is the nucleolus, the site of ribosome biogenesis. Metastable nuclear proteins that misfold upon heat stress enter the nucleolus where they avoid irreversible aggregation and remain competent for Hsp70 dependent refolding upon recovery from stress. Prolonged stress or the uptake of proteins associated with neurodegenerative diseases resulted in loss of reversibility. These findings demonstrate how the properties of a phase-separated compartment can be utilized in protein quality control, a fundamental biological function.
    Recent publications :
    The nucleolus functions as a phase-separated protein quality control compartment.
    Frottin F, Schueder F, Tiwary S, Gupta R, Körner R, Schlichthaerle T, Cox J, Jungmann R, Hartl FU, Hipp MS.
    Science. 2019 Jul 11. pii : eaaw9157. doi : 10.1126/science.aaw9157. [Epub ahead of print]
    In Situ Structure of Neuronal C9orf72 Poly-GA Aggregates Reveals Proteasome Recruitment.
    Guo Q, Lehmer C, Martínez-Sánchez A, Rudack T, Beck F, Hartmann H, Pérez-Berlanga M, Frottin F, Hipp MS, Hartl FU, Edbauer D, Baumeister W, Fernández-Busnadiego R.
    Cell. 2018 Feb 8 ;172(4):696-705.e12. doi : 10.1016/j.cell.2017.12.030. Epub 2018 Feb 1.
    Soluble Oligomers of PolyQ-Expanded Huntingtin Target a Multiplicity of Key Cellular Factors.
    Kim YE, Hosp F, Frottin F, Ge H, Mann M, Hayer-Hartl M, Hartl FU.
    Mol Cell. 2016 Sep 15 ;63(6):951-64. doi : 10.1016/j.molcel.2016.07.022. Epub 2016 Aug 25.

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

  • Vendredi 4 octobre 11:00-12:00 - Johan DECELLE - Plant and Cell Physiology lab, Université Grenoble

    Algal farming in planktonic symbiosis through structural and metabolic transformation

    Résumé : Photosymbiosis between single-celled hosts and microalgae is widely distributed in the oceanic plankton. However, the functioning of this ecologically-important interaction remains enigmatic, particularly the mechanisms that allow the host cell to exploit its intracellular microalgae. Here, using a combination of single-cell structural (3D electron microscopy) and chemical imaging (nanoSIMS, synchrotron X-ray fluorescence), we show how the host reconfigures the photosynthetic machinery and metabolism of its microalgae. Within the host, photosynthetic efficiency is enhanced and the volume of algal cells increases up to ten times with a higher number of chloroplasts. Subcellular mapping of nutrients and N/P ratios shows that symbiotic microalgae are limited in phosphorous, and are transformed into an energy-acquisition machinery. The host also supplies a substantial amount of metals (iron and cobalt) that are stored in high concentration in algal vacuoles. Overall, this study sheds the light on host mechanisms to engineer microalgae in the oceanic plankton. In the near future, we plan to conduct transcriptomics, proteomics and metabolomics studies to better understand the symbiotic interaction, and compare with other photosymbiosis models in freshwater habitats, such as the ciliate Paramecium with the green alga Chlorella.

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

  • Vendredi 15 novembre 11:00-12:00 - David LALAOUNA - Institut de Biologie Moléculaire et Cellulaire, Strasbourg

    séminaire David LALAOUNA

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