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5 results on '"Nicolas Cougot"'

1. MLN51 triggers P-body disassembly and formation of a new type of RNA granules

Author

Annie Cavalier, Edouard Bertrand, Reynald Gillet, Pascale Bellaud, Alain Fautrel, Florence Godey, Aurélie Baguet, Nicolas Cougot, Catherine Tomasetto, Daniel Thomas, Elisabeth Daguenet, Institut de Génétique et Développement de Rennes ( IGDR ), Université de Rennes 1 ( UR1 ), Université de Rennes ( UNIV-RENNES ) -Université de Rennes ( UNIV-RENNES ) -Centre National de la Recherche Scientifique ( CNRS ) -Structure Fédérative de Recherche en Biologie et Santé de Rennes ( Biosit : Biologie - Santé - Innovation Technologique ), Carcinogénèse épithéliale : facteurs prédictifs et pronostiques - UFC ( CEF2P / CARCINO ), Centre Hospitalier Régional Universitaire [Besançon] ( CHRU Besançon ) -Université Bourgogne Franche-Comté ( UBFC ) -Université de Franche-Comté ( UFC ), Plate-forme d'histopathologie, Université de Rennes ( UNIV-RENNES ) -Université de Rennes ( UNIV-RENNES ) -IFR140, Hépatotoxicité et xénobiotiques, Détoxication et réparation Tissulaire, Université de Rennes ( UNIV-RENNES ) -Université de Rennes ( UNIV-RENNES ) -Institut National de la Santé et de la Recherche Médicale ( INSERM ) -Université de Rennes 1 ( UR1 ), Université de Rennes ( UNIV-RENNES ) -Université de Rennes ( UNIV-RENNES ) -Institut National de la Santé et de la Recherche Médicale ( INSERM ) -Foie, métabolismes et cancer, Université de Rennes ( UNIV-RENNES ) -Université de Rennes ( UNIV-RENNES ) -Institut National de la Santé et de la Recherche Médicale ( INSERM ) -Structure Fédérative de Recherche en Biologie et Santé de Rennes ( Biosit : Biologie - Santé - Innovation Technologique ) -Institut National de la Santé et de la Recherche Médicale ( INSERM ) -Structure Fédérative de Recherche en Biologie et Santé de Rennes ( Biosit : Biologie - Santé - Innovation Technologique ), Service de Biologie, CRLCC Eugène Marquis ( CRLCC ), Institut de Génétique Moléculaire de Montpellier ( IGMM ), Université de Montpellier ( UM ) -Centre National de la Recherche Scientifique ( CNRS ), Institut de Génétique et de Biologie Moléculaire et Cellulaire ( IGBMC ), Université de Strasbourg ( UNISTRA ) -Institut National de la Santé et de la Recherche Médicale ( INSERM ) -Centre National de la Recherche Scientifique ( CNRS ), Institut de Génétique et Développement de Rennes (IGDR), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS)-Structure Fédérative de Recherche en Biologie et Santé de Rennes ( Biosit : Biologie - Santé - Innovation Technologique ), Carcinogénèse épithéliale : facteurs prédictifs et pronostiques - UFC (EA 3181) (CEF2P / CARCINO), Centre Hospitalier Régional Universitaire [Besançon] (CHRU Besançon)-Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université de Franche-Comté (UFC), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-IFR140, Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Foie, métabolismes et cancer, Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Structure Fédérative de Recherche en Biologie et Santé de Rennes ( Biosit : Biologie - Santé - Innovation Technologique )-Institut National de la Santé et de la Recherche Médicale (INSERM)-Structure Fédérative de Recherche en Biologie et Santé de Rennes ( Biosit : Biologie - Santé - Innovation Technologique ), CRLCC Eugène Marquis (CRLCC), Institut de Génétique Moléculaire de Montpellier (IGMM), Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM), Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), and Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)

Subjects
0303 health sciences, Messenger RNA, [SDV.GEN]Life Sciences [q-bio]/Genetics, RNA, Cancer, Cell Biology, Biology, medicine.disease, Cell biology, 03 medical and health sciences, 0302 clinical medicine, medicine.anatomical_structure, Stress granule, Cytoplasm, 030220 oncology & carcinogenesis, P-bodies, medicine, Exon junction complex, [ SDV.GEN ] Life Sciences [q-bio]/Genetics, Lymph node, 030304 developmental biology
Abstract

International audience; Metastatic Lymph Node 51 (MLN51) is a core component of the exon junction complex (EJC), which is loaded on spliced mRNAs and plays an essential role in their fate. Unlike the three other EJC core components (eIF4AIII, Magoh and Y14), MLN51 is mainly located in the cytoplasm where it plays a key role in stress granules assembly. In this study, we further investigated the cytoplasmic role of MLN51. We show that MLN51 is a new component of processing bodies (P-bodies). When overexpressed, MLN51 localizes in novel small cytoplasmic foci. These contain RNA, show directed movements, and are distinct from stress granules and P-bodies. The appearance of these foci correlates with the process of P-body disassembly. A similar reduction in PB count is also observed in human HER2+ breast cancer cells overexpressing MLN51. This suggests that P-body disassembly and subsequent mRNA deregulation may correlate to cancer progression.

Published
2014
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2. Visualizing Compaction of Polysomes in Bacteria

Author

Jérémy Delesques, Annie Cavalier, Anne-Elisabeth Molza, Jean-Paul Rolland, Emmanuel Giudice, Reynald Gillet, Gwennola Ermel, Carlos Blanco, Daniel Thomas, Nicolas Cougot, Institut de Génétique et Développement de Rennes (IGDR), Université de Rennes (UR)-Centre National de la Recherche Scientifique (CNRS)-Structure Fédérative de Recherche en Biologie et Santé de Rennes ( Biosit : Biologie - Santé - Innovation Technologique ), Microbiologie : Risques Infectieux, Université de Rennes (UR)-CHU Pontchaillou [Rennes]-Structure Fédérative de Recherche en Biologie et Santé de Rennes ( Biosit : Biologie - Santé - Innovation Technologique )-Université de Rennes - UFR d'Odontologie (UR Odontologie), Université de Rennes (UR)-Université de Rennes (UR), Structure Fédérative de Recherche en Biologie et Santé de Rennes ( Biosit : Biologie - Santé - Innovation Technologique )-Centre National de la Recherche Scientifique (CNRS)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES), Université de Rennes 1 (UR1), and Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-CHU Pontchaillou [Rennes]-Faculté de Chirurgie Dentaire de Rennes-Faculté d'Odontologie-Structure Fédérative de Recherche en Biologie et Santé de Rennes ( Biosit : Biologie - Santé - Innovation Technologique )

Subjects
tmRNA, Electron Microscope Tomography, BSA, Macromolecular Substances, mRNA, RT-PCR, electron tomography, Biology, Ribosome, 03 medical and health sciences, Imaging, Three-Dimensional, reverse transcription PCR, Structural Biology, Polysome, bovine serum albumin, transmission electron microscopy, Escherichia coli, Protein biosynthesis, RNA, Messenger, GST, Molecular Biology, 030304 developmental biology, Polyproline helix, glutathione S-transferase, polysomes, 0303 health sciences, Messenger RNA, 030302 biochemistry & molecular biology, RNA, transfer-messenger RNA, Ribosomal RNA, [SDV.MP.BAC]Life Sciences [q-bio]/Microbiology and Parasitology/Bacteriology, Cell biology, Biochemistry, ribosome, Polyribosomes, Protein Biosynthesis, TEM, Peptides, three dimensional, Transfer-messenger RNA, 3D
Abstract

International audience; During protein synthesis, many translating ribosomes are bound together with an mRNA molecule to form polysomes (or polyribosomes). While the spatial organization of bacterial polysomes has been well studied in vitro, little is known about how they cluster when cellular conditions are highly constrained. To better understand this, we used electron tomography, template matching, and three-dimensional modeling to analyze the supramolecular network of ribosomes after induction of translational pauses. In Escherichia coli, we overexpressed an mRNA carrying a polyproline motif known to induce pausing during translation. When working with a strain lacking transfer-messenger RNA, the principle actor in the "trans-translation" rescuing system, the cells survived the hijacking of the translation machinery but this resulted in a sharp modification of the ribosomal network. The results of our experiments demonstrate that single ribosomes are replaced with large amounts of compacted polysomes. These polysomes are highly organized, principally forming hairpins and dimers of hairpins that stack together. We propose that these spatial arrangements help maintain translation efficiency when the rescue systems are absent or overwhelmed.

Published
2013
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3. The dual organization of P-bodies revealed by immunoelectron microscopy and electron tomography

Author

Nicolas Cougot, Annie Cavalier, Daniel Thomas, Reynald Gillet, Institut de Génétique et Développement de Rennes (IGDR), Université de Rennes (UR)-Centre National de la Recherche Scientifique (CNRS)-Structure Fédérative de Recherche en Biologie et Santé de Rennes ( Biosit : Biologie - Santé - Innovation Technologique ), N.C. was supported by a post-doctoral fellowship from the 'Ligue Nationale Contre le Cancer'. This work was supported by grants ANR-08JCJC-0027-01 and ANR-09-MIE to R.G. and by Rennes Métropole funding., ANR-08-JCJC-0027,tmRNA,Structural analysis of the late steps of trans-translation by means of cryo-electron microscopy(2008), De Villemeur, Hervé, Jeunes chercheuses et jeunes chercheurs - Structural analysis of the late steps of trans-translation by means of cryo-electron microscopy - - tmRNA2008 - ANR-08-JCJC-0027 - JCJC - VALID, Université de Rennes 1 (UR1), and Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS)-Structure Fédérative de Recherche en Biologie et Santé de Rennes ( Biosit : Biologie - Santé - Innovation Technologique )

Subjects
Cytoplasm, Electron Microscope Tomography, [SDV.IB.IMA]Life Sciences [q-bio]/Bioengineering/Imaging, RNA Stability, electron tomography, MESH: Electron Microscope Tomography, Ribosome, Structural Biology, MESH: Microscopy, Immunoelectron, Microscopy, Immunoelectron, Ribonucleoprotein, 0303 health sciences, MESH: Cells, 030302 biochemistry & molecular biology, micro-RNA, MESH: RNA Stability, Immunogold labelling, MESH: Gene Expression Regulation, Cell biology, Mitochondria, Ribonucleoproteins, MESH: Mitochondria, Immunoelectron microscopy, Cells, MESH: Cytoplasmic Granules, Biology, Cytoplasmic Granules, Cell Line, 03 medical and health sciences, immunoelectron microscopy, P-bodies, [SDV.BBM] Life Sciences [q-bio]/Biochemistry, Molecular Biology, Humans, [SDV.BBM]Life Sciences [q-bio]/Biochemistry, Molecular Biology, RNA, Messenger, Molecular Biology, 030304 developmental biology, MESH: RNA, Messenger, MESH: Humans, MESH: Cytoplasm, MESH: Multiprotein Complexes, MESH: Cell Line, MESH: Ribonucleoproteins, [SDV.IB.IMA] Life Sciences [q-bio]/Bioengineering/Imaging, Freeze substitution, Electron tomography, Gene Expression Regulation, Multiprotein Complexes, RNA, Ribosomes, MESH: Ribosomes
Abstract

International audience; Processing bodies (P-bodies) are cytoplasmic non-membranous domains involved in the regulation of eukaryotic gene expression. Since their discovery, several studies using fluorescence-based strategies have uncovered their pivotal role in mRNA metabolism, particularly during translation repression and/or mRNA degradation. Yet, P-bodies still remain a "black box" in which numerous proteins accumulate next to RNAs to regulate their fate by unknown mechanisms. In this study, we investigated the ultrastructural organization of P-bodies in human cells. Using a wide range of original electron microscopy strategies, including high-pressure freezing and freeze substitution, we found that P-bodies are huge ribonucleoprotein complexes located in the close proximity of mitochondria and ribosomes, in which regulatory factors exhibit differential localization depending on their activity on mRNAs. We describe the first experiment pairing immunogold labeling with electron tomography (immunoelectron tomography) of a human P-body. Overall, the results depict a P-body organization that comprises at least two distinct compartments: a dense core on which peripheral protrusions are anchored.

Published
2012
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4. The exon-junction-complex-component metastatic lymph node 51 functions in stress-granule assembly

Author

Marie-Christine Rio, Marie-Pierre Chenard, Edouard Bertrand, Sébastien Degot, Hervé Le Hir, Catherine Tomasetto, Aurélie Baguet, Pascal Kessler, Corinne Wendling, Nicolas Cougot, Institut de Génétique Moléculaire de Montpellier (IGMM), Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM), Institut de génétique et biologie moléculaire et cellulaire (IGBMC), Université Louis Pasteur - Strasbourg I-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), Centre de génétique moléculaire (CGM), Centre National de la Recherche Scientifique (CNRS), Laboratoire de Biologie structurale, Institut National de la Santé et de la Recherche Médicale (INSERM), Institut de Génétique Moléculaire de Montpellier ( IGMM ), Université de Montpellier ( UM ) -Centre National de la Recherche Scientifique ( CNRS ), Institut de génétique et biologie moléculaire et cellulaire ( IGBMC ), Université Louis Pasteur - Strasbourg I-Institut National de la Santé et de la Recherche Médicale ( INSERM ) -Centre National de la Recherche Scientifique ( CNRS ), Centre de génétique moléculaire ( CGM ), Centre National de la Recherche Scientifique ( CNRS ), Biologie moléculaire et génie génétique ( IGBMC ), Institut National de la Santé et de la Recherche Médicale ( INSERM ), and Biologie moléculaire et génie génétique (IGBMC)

Subjects
Cell Survival, Mutant, Down-Regulation, Gene Expression, Breast Neoplasms, [ SDV.BBM.BM ] Life Sciences [q-bio]/Biochemistry, Molecular Biology/Molecular biology, Biology, Cytoplasmic Granules, 03 medical and health sciences, Membrane Microdomains, 0302 clinical medicine, Stress granule, Humans, Gene silencing, Stress granule assembly, Phosphorylation, 030304 developmental biology, Genetics, 0303 health sciences, Binding protein, Nuclear Proteins, RNA-Binding Proteins, RNA, [SDV.BBM.BM]Life Sciences [q-bio]/Biochemistry, Molecular Biology/Molecular biology, Exons, Cell Biology, Neoplasm Proteins, Up-Regulation, Cell biology, Gene Expression Regulation, Neoplastic, Eukaryotic Initiation Factor-2B, Protein Transport, Cytoplasm, Exon junction complex, Female, 030217 neurology & neurosurgery, HeLa Cells, Protein Binding
Abstract

Metastatic lymph node 51 [MLN51 (also known as CASC3)] is a component of the exon junction complex (EJC), which is assembled on spliced mRNAs and plays important roles in post-splicing events. The four proteins of the EJC core, MLN51, MAGOH, Y14 and EIF4AIII shuttle between the cytoplasm and the nucleus. However, unlike the last three, MLN51 is mainly detected in the cytoplasm, suggesting that it plays an additional function in this compartment. In the present study, we show that MLN51 is recruited into cytoplasmic aggregates known as stress granules (SGs) together with the SG-resident proteins, fragile X mental retardation protein (FMRP), poly(A) binding protein (PABP) and poly(A)+ RNA. MLN51 specifically associates with SGs via its C-terminal region, which is dispensable for its incorporation in the EJC. MLN51 does not promote SG formation but its silencing, or the overexpression of a mutant lacking its C-terminal region, alters SG assembly. Finally, in human breast carcinomas, MLN51 is sometimes present in cytoplasmic foci also positive for FMRP and PABP, suggesting that SGs formation occurs in malignant tumours.

Published
2007
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5. Inhibition of translational initiation by Let-7 microRNA in human cells

Author

Witold Filipowicz, Tabea Zoller, Nicolas Cougot, Edouard Bertrand, Suvendra N. Bhattacharyya, Caroline G. Artus, Ramesh S. Pillai, Eugenia Basyuk, Institut de Génétique Moléculaire de Montpellier (IGMM), and Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)

Subjects
RNA Caps, Eukaryotic Initiation Factor-2, Biology, 03 medical and health sciences, 0302 clinical medicine, Eukaryotic translation, caenorhabditis-elegans processing bodies messenger-rnas protein-synthesis eif4e mechanisms expression sites decay, Peptide Initiation Factors, microRNA, Gene expression, Gene silencing, Humans, [SDV.BBM]Life Sciences [q-bio]/Biochemistry, Molecular Biology, RNA, Messenger, Peptide Chain Initiation, Translational, 030304 developmental biology, AU-rich element, 0303 health sciences, Multidisciplinary, RNA, Translation (biology), Argonaute, Molecular biology, Cell biology, MicroRNAs, Ribonucleoproteins, 030220 oncology & carcinogenesis, Argonaute Proteins, HeLa Cells
Abstract

MicroRNAs (miRNAs) are ∼21-nucleotide-long RNA molecules regulating gene expression in multicellular eukaryotes. In metazoa, miRNAs act by imperfectly base-pairing with the 3′ untranslated region of target messenger RNAs (mRNAs) and repressing protein accumulation by an unknown mechanism. We demonstrate that endogenous let-7 microribonucleoproteins (miRNPs) or the tethering of Argonaute (Ago) proteins to reporter mRNAs in human cells inhibit translation initiation. M 7 G-cap-independent translation is not subject to repression, suggesting that miRNPs interfere with recognition of the cap. Repressed mRNAs, Ago proteins, and miRNAs were all found to accumulate in processing bodies. We propose that localization of mRNAs to these structures is a consequence of translational repression.

Published
2005
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