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Team Publications Maintenance of Transcriptional Repression by Polycomb Proteins Team Publications Maintenance of Transcriptional Repression by Polycomb Proteins Year of publication 2019 Michel Wassef, Eric Pasmant, Raphaël Margueron (2019 Oct 3) “MPNST Epigenetics”-Letter. Molecular cancer research : MCR : 2139 : DOI : 10.1158/1541-7786.MCR-19-0680 Summary Roberta Ragazzini, Raquel Pérez-Palacios, Irem H Baymaz, Seynabou Diop, Katia Ancelin, Dina Zielinski, Audrey Michaud, Maëlle Givelet, Mate Borsos, Setareh Aflaki, Patricia Legoix, Pascal W T C Jansen, Nicolas Servant, Maria-Elena Torres-Padilla, Deborah Bourc'his, Pierre Fouchet, Michiel Vermeulen, Raphaël Margueron (2019 Aug 26) EZHIP constrains Polycomb Repressive Complex 2 activity in germ cells. Nature communications : 10 : 1-18 : DOI : 10.1038/s41467-019-11800-x Summary The Polycomb group of proteins is required for the proper orchestration of gene expression due to its role in maintaining transcriptional silencing. It is composed of several chromatin modifying complexes, including Polycomb Repressive Complex 2 (PRC2), which deposits H3K27me2/3. Here, we report the identification of a cofactor of PRC2, EZHIP (EZH1/2 Inhibitory Protein), expressed predominantly in the gonads. EZHIP limits the enzymatic activity of PRC2 and lessens the interaction between the core complex and its accessory subunits, but does not interfere with PRC2 recruitment to chromatin. Deletion of Ezhip in mice leads to a global increase in H3K27me2/3 deposition both during spermatogenesis and at late stages of oocyte maturation. This does not affect the initial number of follicles but is associated with a reduction of follicles in aging. Our results suggest that mature oocytes Ezhip-/- might not be fully functional and indicate that fertility is strongly impaired in Ezhip-/- females. Altogether, our study uncovers EZHIP as a regulator of chromatin landscape in gametes. Sabrina Bondu, Anne-Sophie Alary, Carine Lefèvre, Alexandre Houy, Grace Jung, Thibaud Lefebvre, David Rombaut, Ismael Boussaid, Abderrahmane Bousta, François Guillonneau, Prunelle Perrier, Samar Alsafadi, Michel Wassef, Raphaël Margueron, Alice Rousseau, Nathalie Droin, Nicolas Cagnard, Sophie Kaltenbach, Susann Winter, Anne-Sophie Kubasch, Didier Bouscary, Valeria Santini, Andrea Toma, Mathilde Hunault, Aspasia Stamatoullas, Emmanuel Gyan, Thomas Cluzeau, Uwe Platzbecker, Lionel Adès, Hervé Puy, Marc-Henri Stern, Zoubida Karim, Patrick Mayeux, Elizabeta Nemeth, Sophie Park, Tomas Ganz, Léon Kautz, Olivier Kosmider, Michaëla Fontenay (2019 Jul 12) A variant erythroferrone disrupts iron homeostasis in -mutated myelodysplastic syndrome. INSTITUT CURIE, 20 rue d’Ulm, 75248 Paris Cedex 05, France | 1 Team Publications Maintenance of Transcriptional Repression by Polycomb Proteins Science translational medicine : DOI : eaav5467 Summary Myelodysplastic syndromes (MDS) with ring sideroblasts are hematopoietic stem cell disorders with erythroid dysplasia and mutations in the splicing factor gene. Patients with MDS with mutations often accumulate excessive tissue iron, even in the absence of transfusions, but the mechanisms that are responsible for their parenchymal iron overload are unknown. Body iron content, tissue distribution, and the supply of iron for erythropoiesis are controlled by the hormone hepcidin, which is regulated by erythroblasts through secretion of the erythroid hormone erythroferrone (ERFE). Here, we identified an alternative transcript in patients with MDS with the mutation. Induction of this transcript in primary - mutated bone marrow erythroblasts generated a variant protein that maintained the capacity to suppress hepcidin transcription. Plasma concentrations of ERFE were higher in patients with MDS with an gene mutation than in patients with wild-type MDS. Thus, hepcidin suppression by a variant ERFE is likely responsible for the increased iron loading in patients with -mutated MDS, suggesting that ERFE could be targeted to prevent iron-mediated toxicity. The expression of the variant transcript that was restricted to -mutated erythroblasts decreased in lenalidomide-responsive anemic patients, identifying variant ERFE as a specific biomarker of clonal erythropoiesis. Andrea Frapporti, Caridad Miró Pina, Olivier Arnaiz, Daniel Holoch, Takayuki Kawaguchi, Adeline Humbert, Evangelia Eleftheriou, Bérangère Lombard, Damarys Loew, Linda Sperling, Karine Guitot, Raphaël Margueron, Sandra Duharcourt (2019 Jun 22) The Polycomb protein Ezl1 mediates H3K9 and H3K27 methylation to repress transposable elements in Paramecium. Nature communications : 2710 : DOI : 10.1038/s41467-019-10648-5 Summary In animals and plants, the H3K9me3 and H3K27me3 chromatin silencing marks are deposited by different protein machineries. H3K9me3 is catalyzed by the SET-domain SU(VAR)3-9 enzymes, while H3K27me3 is catalyzed by the SET-domain Enhancer-of-zeste enzymes, which are the catalytic subunits of Polycomb Repressive Complex 2 (PRC2). Here, we show that the Enhancer-of-zeste-like protein Ezl1 from the unicellular eukaryote Paramecium tetraurelia, which exhibits significant sequence and structural similarities with human EZH2, catalyzes methylation of histone H3 in vitro and in vivo with an apparent specificity toward K9 and K27. We find that H3K9me3 and H3K27me3 co-occur at multiple families of transposable elements in an Ezl1-dependent manner. We demonstrate that loss of these histone marks results in global transcriptional hyperactivation of transposable elements with modest effects on protein-coding gene expression. Our study suggests that although often considered functionally distinct, H3K9me3 and H3K27me3 may share a common evolutionary history as well as a common ancestral role in silencing transposable elements. INSTITUT CURIE, 20 rue d’Ulm, 75248 Paris Cedex 05, France | 2 Team Publications Maintenance of Transcriptional Repression by Polycomb Proteins Michel Wassef, Armelle Luscan, Setareh Aflaki, Dina Zielinski, Pascal W T C Jansen, H Irem Baymaz, Aude Battistella, Carole Kersouani, Nicolas Servant, Margaret R Wallace, Pierre Romero, Olivier Kosmider, Pierre-Alexandre Just, Mikaël Hivelin, Sébastien Jacques, Anne Vincent- Salomon, Michiel Vermeulen, Michel Vidaud, Eric Pasmant, Raphaël Margueron (2019 Mar 15) EZH1/2 function mostly within canonical PRC2 and exhibit proliferation- dependent redundancy that shapes mutational signatures in cancer. Proceedings of the National Academy of Sciences of the United States of America : 6075-6080 : DOI : 10.1073/pnas.1814634116 Summary Genetic mutations affecting chromatin modifiers are widespread in cancers. In malignant peripheral nerve sheath tumors (MPNSTs), Polycomb repressive complex 2 (PRC2), which plays a crucial role in gene silencing, is inactivated through recurrent mutations in core subunits embryonic ectoderm development (EED) and suppressor of zeste 12 homolog (SUZ12), but mutations in PRC2’s main catalytic subunit enhancer of zeste homolog 2 (EZH2) have never been found. This is in contrast to myeloid and lymphoid malignancies, which harbor frequent loss-of-function mutations in EZH2. Here, we investigated whether the absence of EZH2 mutations in MPNST is due to a PRC2-independent (i.e., noncanonical) function of the enzyme or to redundancy with EZH1. We show that, in the absence of SUZ12, EZH2 remains bound to EED but loses its interaction with all other core and accessory PRC2 subunits. Through genetic and pharmacological analyses, we unambiguously establish that EZH2 is functionally inert in this context, thereby excluding a PRC2-independent function. Instead, we show that EZH1 and EZH2 are functionally redundant in the slowly proliferating MPNST precursors. We provide evidence that the compensatory function of EZH1 is alleviated upon higher proliferation. This work reveals how context-dependent redundancies can shape tumor-type specific mutation patterns in chromatin regulators. CAMPAGNE Antoine, LEE Ming-Kang, ZIELINSKI Dina, MICHAUD Audrey, LE CORRE Stéphanie, DINGLI Florent, CHEN Hong, SHAHIDIAN Lara Z, SERVANT Nicolas, LOEW Damarys, PASMANT Eric, PISTEL-VINAY Sophie, WASSEF Michel, MARGUERON Raphaël (2019 Jan 21) BAP1 complex promotes transcription by opposing PRC1-mediated H2A ubiquitylation Nature Communications : 10 : 1-15 : DOI : 10.1038/s41467-018-08255-x Summary In Drosophila, a complex consisting of Calypso and ASX catalyzes H2A deubiquitination and has been reported to act as part of the Polycomb machinery in transcriptional silencing. The mammalian homologs of these proteins (BAP1 and ASXL1/2/3, respectively), are frequently mutated in various cancer types, yet their precise functions remain unclear. Using an integrative approach based on isogenic cell lines generated with CRISPR/Cas9, we uncover an unanticipated role for BAP1 in gene activation. This function requires the assembly of an enzymatically active BAP1-associated core complex (BAP1.com) containing one of the INSTITUT CURIE, 20 rue d’Ulm, 75248 Paris Cedex 05, France | 3 Team Publications Maintenance of Transcriptional Repression by Polycomb Proteins redundant ASXL proteins. We investigate the mechanism underlying BAP1.com-mediated transcriptional regulation and show that it does not participate in Polycomb-mediated silencing. Instead, our results establish that the function of BAP1.com is to safeguard transcriptionally active genes against silencing by the Polycomb Repressive Complex 1. Year of publication 2018 Yan Wang, Haizhen Long, Juan Yu, Liping Dong, Michel Wassef, Baowen Zhuo, Xia Li, Jicheng Zhao, Min Wang, Cuifang Liu, Zengqi Wen, Luyuan Chang, Ping Chen, Qian-Fei Wang, Xueqing
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