Dynamique de la Chromatine

Publications de l’équipe

Année de publication : 2018

Tejas Yadav, Jean-Pierre Quivy, Geneviève Almouzni. (2018 Sep 26)

Chromatin plasticity: A versatile landscape that underlies cell fate and identity.

Science : Vol. 361, Issue 6409:1332-1336 : DOI : DOI: 10.1126/science.aat8950 En savoir plus
Résumé

Chromatin plasticity: A versatile landscape that underlies cell fate and identity.

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Roberto Bellelli, Ondrej Belan,Valerie E. Pye,Camille Clement, Sarah L. Maslen,J. Mark Skehel, Peter Cherepanov,Genevieve Almouzni,and Simon J. Boulton. (2018 Sep 11)

POLE3-POLE4 Is a Histone H3-H4 Chaperone that Maintains Chromatin Integrity during DNA Replication

Molecular Cell : 72, 112–126 : DOI : DOI:https://doi.org/10.1016/j.molcel.2018.08.043 En savoir plus
Résumé

POLE3-POLE4 Is a Histone H3-H4 Chaperone that Maintains Chromatin Integrity during DNA Replication

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Shweta Mendiratta, Alberto Gatto,  Genevieve Almouzni. (2018 Aug 28)

Histone supply: Multitiered regulation ensures chromatin dynamics throughout the cell cycle.

Journal of Cell Biology : DOI : DOI: 10.1083/jcb.201807179 En savoir plus
Résumé

Histone supply: Multitiered regulation ensures chromatin dynamics throughout the cell cycle.

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Camille Clément, Guillermo A. Orsi, Alberto Gatto, Ekaterina Boyarchuk, Audrey Forest, Bassam Hajj, Judith Miné-Hattab, Mickaël Garnier, Zachary A. Gurard-Levin, Jean-Pierre Quivy & Geneviève Almouzni. (2018 Aug 9)

High-resolution visualization of H3 variants during replication reveals their controlled recycling

Nature Communications : 9:31-81. En savoir plus
Résumé

High-resolution visualization of H3 variants during replication reveals their controlled recycling

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Dominique Ray-Gallet, M. Daniel Rickett, Yukari Sato,  Kushol Gupta, Ekaterina Boyarchuk, Toshiya Senda, Ronen Marmorstein  & Geneviève Almouzni. (2018 Aug 6)

Functional activity of the H3.3 histone chaperone complex HIRA requires trimerization of the HIRA

Nature Communications : 9: 3103 : DOI : DOI: 10.1038/s41467-018-05581-y En savoir plus
Résumé

Functional activity of the H3.3 histone chaperone complex HIRA requires trimerization of the HIRA subunit

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Aaron Mendez-Bermudez, Liudmyla Lototska, Serge Bauwens, Marie-Josèphe Giraud-Panis, Olivier Croce, Karine Jamet, Agurtzane Irizar, Macarena Mowinckel, Stephane Koundrioukoff, Nicolas Nottet, Genevieve Almouzni, Mare-Paule Teulade-Fichou, Michael Schertzer, Mylène Perderiset, Arturo Londoño-Vallejo, Michelle Debatisse, Eric Gilson, Jing Ye (2018 May 3)

Genome-wide Control of Heterochromatin Replication by the Telomere Capping Protein TRF2

Molecular cell : 70 : 449-461.e5 : DOI : 10.1016/j.molcel.2018.03.036 En savoir plus
Résumé

Hard-to-replicate regions of chromosomes (e.g., pericentromeres, centromeres, and telomeres) impede replication fork progression, eventually leading, in the event of replication stress, to chromosome fragility, aging, and cancer. Our knowledge of the mechanisms controlling the stability of these regions is essentially limited to telomeres, where fragility is counteracted by the shelterin proteins. Here we show that the shelterin subunit TRF2 ensures progression of the replication fork through pericentromeric heterochromatin, but not centromeric chromatin. In a process involving its N-terminal basic domain, TRF2 binds to pericentromeric Satellite III sequences during S phase, allowing the recruitment of the G-quadruplex-resolving helicase RTEL1 to facilitate fork progression. We also show that TRF2 is required for the stability of other heterochromatic regions localized throughout the genome, paving the way for future research on heterochromatic replication and its relationship with aging and cancer.

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Année de publication : 2017

D Morel, G Almouzni, J-C Soria, S Postel-Vinay (2017 Apr 21)

Targeting chromatin defects in selected solid tumors based on oncogene addiction, synthetic lethality and epigenetic antagonism.

Annals of oncology : official journal of the European Society for Medical Oncology : 254-269 : DOI : 10.1093/annonc/mdw552 En savoir plus
Résumé

Although the role of epigenetic abnormalities has been studied for several years in cancer genesis and development, epigenetic-targeting drugs have historically failed to demonstrate efficacy in solid malignancies. However, successful targeting of chromatin remodeling deficiencies, histone writers and histone reader alterations has been achieved very recently using biomarker-driven and mechanism-based approaches. Epigenetic targeting is now one of the most active areas in drug development and could represent novel therapeutic opportunity for up to 25% of all solid tumors.

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Dan Filipescu, Monica Naughtin, Katrina Podsypanina, Vincent Lejour, Laurence Wilson, Zachary A Gurard-Levin, Guillermo A Orsi, Iva Simeonova, Eleonore Toufektchan, Laura D Attardi, Franck Toledo, Geneviève Almouzni (2017 Mar 31)

Essential role for centromeric factors following p53 loss and oncogenic transformation.

Genes & development : 463-480 : DOI : 10.1101/gad.290924.116 En savoir plus
Résumé

In mammals, centromere definition involves the histone variant CENP-A (centromere protein A), deposited by its chaperone, HJURP (Holliday junction recognition protein). Alterations in this process impair chromosome segregation and genome stability, which are also compromised by p53 inactivation in cancer. Here we found that CENP-A and HJURP are transcriptionally up-regulated in p53-null human tumors. Using an established mouse embryonic fibroblast (MEF) model combining p53 inactivation with E1A or HRas-V12 oncogene expression, we reproduced a similar up-regulation of HJURP and CENP-A. We delineate functional CDE/CHR motifs within the Hjurp and Cenpa promoters and demonstrate their roles in p53-mediated repression. To assess the importance of HJURP up-regulation in transformed murine and human cells, we used a CRISPR/Cas9 approach. Remarkably, depletion of HJURP leads to distinct outcomes depending on their p53 status. Functional p53 elicits a cell cycle arrest response, whereas, in p53-null transformed cells, the absence of arrest enables the loss of HJURP to induce severe aneuploidy and, ultimately, apoptotic cell death. We thus tested the impact of HJURP depletion in pre-established allograft tumors in mice and revealed a major block of tumor progression in vivo. We discuss a model in which an « epigenetic addiction » to the HJURP chaperone represents an Achilles’ heel in p53-deficient transformed cells.

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Paul Victor Sauer, Jennifer Timm, Danni Liu, David Sitbon, Elisabetta Boeri-Erba, Christophe Velours, Norbert Mücke, Jörg Langowski, Françoise Ochsenbein, Geneviève Almouzni, Daniel Panne (2017 Mar 19)

Insights into the molecular architecture and histone H3-H4 deposition mechanism of yeast Chromatin assembly factor 1.

eLife : DOI : 10.7554/eLife.23474 En savoir plus
Résumé

How the very first step in nucleosome assembly, deposition of histone H3-H4 as tetramers or dimers on DNA, is accomplished remains largely unclear. Here, we report that yeast chromatin assembly factor 1 (CAF1), a conserved histone chaperone complex that deposits H3-H4 during DNA replication, binds a single H3-H4 heterodimer in solution. We identify a new DNA-binding domain in the large Cac1 subunit of CAF1, which is required for high-affinity DNA binding by the CAF1 three-subunit complex, and which is distinct from the previously described C-terminal winged-helix domain. CAF1 binds preferentially to DNA molecules longer than 40 bp, and two CAF1-H3-H4 complexes concertedly associate with DNA molecules of this size, resulting in deposition of H3-H4 tetramers. While DNA binding is not essential for H3-H4 tetrasome deposition in vitro, it is required for efficient DNA synthesis-coupled nucleosome assembly. Mutant histones with impaired H3-H4 tetramerization interactions fail to release from CAF1, indicating that DNA deposition of H3-H4 tetramers by CAF1 requires a hierarchical cooperation between DNA binding, H3-H4 deposition and histone tetramerization.

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Christèle Maison, Jean-Pierre Quivy, Geneviève Almouzni (2017 Jan 17)

Suv39h1 links the SUMO pathway to constitutive heterochromatin.

Molecular & cellular oncology : e1225546 : DOI : 10.1080/23723556.2016.1225546 En savoir plus
Résumé

The Suv39h lysine methyltransferases, known as key enzymes responsible for histone H3 lysine 9 methylation, are critical for heterochromatin protein 1 enrichment at constitutive heterochromatin. Our recent findings reveal a new role for the Suv39h1 paralog that links it to SUMO pathway function at constitutive heterochromatin.

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Année de publication : 2016

Sebastian Müller, Geneviève Almouzni (2016 Dec 1)

Chromatin dynamics during the cell cycle at centromeres.

Nature Reviews Genetics : 192-208 : DOI : 10.1038/nrg.2016.157 En savoir plus
Résumé

Centromeric chromatin undergoes major changes in composition and architecture during each cell cycle. These changes in specialized chromatin facilitate kinetochore formation in mitosis to ensure proper chromosome segregation. Thus, proper orchestration of centromeric chromatin dynamics during interphase, including replication in S phase, is crucial. We provide the current view concerning the centromeric architecture associated with satellite repeat sequences in mammals and its dynamics during the cell cycle. We summarize the contributions of deposited histone variants and their chaperones, other centromeric components – including proteins and their post-translational modifications, and RNAs – and we link the expression and deposition timing of each component during the cell cycle. Because neocentromeres occur at ectopic sites, we highlight how cell cycle processes can go wrong, leading to neocentromere formation and potentially disease.

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Nicolas Lacoste, Wajid Bhat, Jacques Côté (2016 Nov 18)

Purification of Yeast Native Reagents for the Analysis of Chromatin Function-II: Multiprotein Complexes and Biochemical Assays.

Methods in molecular biology (Clifton, N.J.) : 53-67 En savoir plus
Résumé

Post-translational modifications of histones play essential roles in regulating chromatin structure and function. These are tightly regulated in vivo and there is an intricate cross-talk between different marks as they are recognized by specific reader modules present in a large number of nuclear factors. In order to precisely dissect these processes in vitro native reagents like purified chromatin and histone modifying/remodeling enzymes are required to more accurately reproduce physiological conditions. The vast majority of these enzymes need to be part of stable multiprotein complexes with cofactors enabling them to act on chromatin substrates and/or read specific histone marks. In the accompanying chapter, we have described the protocol for purification of native chromatin from yeast cells (Chapter 3 ). Here, we present the methods to obtain highly purified native chromatin modifying complexes from Saccharomyces cerevisiae, based on Tandem Affinity Purification (TAP). We also present possible applications and useful functional assays that can be performed using these yeast native reagents.

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Nicolas Lacoste, Wajid Bhat, Jacques Côté (2016 Nov 18)

Purification of Yeast Native Reagents for the Analysis of Chromatin Function-I: Nucleosomes for Reconstitution and Manipulation of Histone Marks.

Methods in molecular biology (Clifton, N.J.) : 39-51 En savoir plus
Résumé

Purification of native biological material provides powerful tools for the functional analysis of enzymes and proteins in chromatin. In particular, histone proteins harbor numerous post-translational modifications, which may differ between species, tissues, and growth conditions and are lacking on recombinant histones. Moreover, the physiological substrate of most enzymes that modify histones is chromatin and the majority of these enzymes need to be part of a multiprotein assembly to be able to act on chromatin. For the yeast Saccharomyces cerevisiae different chromatin purification protocols are available but often result in poor yields or rely on genetic manipulation. We present a simple purification protocol that can yield up to 150 μg of pure native chromatin per liter of yeast culture. The purified material can be obtained from mutant cells lacking specific histone modifications and can be used in in vitro chromatin assembly for biochemical studies. Based on the extremely high degree of conservation throughout eukaryotes, this modifiable native chromatin can be used in studies with factors from other organisms including humans.

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Guillermo A Orsi, Monica Naughtin, Geneviève Almouzni (2016 Nov 5)

The Epigenome and Cancer Stem Cell Fate: Connected by a Linker Histone Variant.

Cell stem cell : 567-568 : DOI : S1934-5909(16)30350-2 En savoir plus
Résumé

The molecular features underlying tumor heterogeneity and the role of chromatin components in regulating cell fate within tumors are not well understood. Recently in Science, Torres et al. (2016) showed that the linker histone variant H1.0 functions as a chromatin switch that determines self-renewal versus differentiation decisions in cancer stem cells.

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Salomé Adam, Juliette Dabin, Odile Chevallier, Olivier Leroy, Céline Baldeyron, Armelle Corpet, Patrick Lomonte, Olivier Renaud, Geneviève Almouzni, Sophie E Polo (2016 Sep 20)

Real-Time Tracking of Parental Histones Reveals Their Contribution to Chromatin Integrity Following DNA Damage.

Molecular cell : DOI : S1097-2765(16)30461-0 En savoir plus
Résumé

Chromatin integrity is critical for cell function and identity but is challenged by DNA damage. To understand how chromatin architecture and the information that it conveys are preserved or altered following genotoxic stress, we established a system for real-time tracking of parental histones, which characterize the pre-damage chromatin state. Focusing on histone H3 dynamics after local UVC irradiation in human cells, we demonstrate that parental histones rapidly redistribute around damaged regions by a dual mechanism combining chromatin opening and histone mobilization on chromatin. Importantly, parental histones almost entirely recover and mix with new histones in repairing chromatin. Our data further define a close coordination of parental histone dynamics with DNA repair progression through the damage sensor DDB2 (DNA damage-binding protein 2). We speculate that this mechanism may contribute to maintaining a memory of the original chromatin landscape and may help preserve epigenome stability in response to DNA damage.

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