1
|
PRC1-independent binding and activity of RYBP on the KSHV genome during de novo infection. PLoS Pathog 2022; 18:e1010801. [PMID: 36026503 PMCID: PMC9455864 DOI: 10.1371/journal.ppat.1010801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Revised: 09/08/2022] [Accepted: 08/08/2022] [Indexed: 11/19/2022] Open
Abstract
Kaposi’s sarcoma-associated herpesvirus (KSHV) is an oncogenic virus that causes lifelong infection in humans by establishing latency after primary infection. Latent infection is a prerequisite for both persistent infection and the development of KSHV-associated cancers. While viral lytic genes are transiently expressed after primary infection, their expression is significantly restricted and concomitant with the binding of host epigenetic repressors Polycomb Repressive Complex 1 and 2 (PRC1 and PRC2) to lytic genes. PRC1 and PRC2 mediate the repressive histone marks H2AK119ub and H3K27me3, respectively, and maintain heterochromatin structure on KSHV lytic genes to inhibit their expression. In contrast to PRC2, little is known about the recruitment and role of PRC1 factors on the KSHV genome following de novo infection. Thus, the goal of this study was to examine the function of PRC1 factors in the establishment of KSHV latency. To address this question, we performed an shRNA screen targeting 7 different components of the canonical and non-canonical PRC1 complexes during primary KSHV infection. We found that RYBP, a main subunit of the non-canonical PRC1 complexes, is a potent repressor of KSHV lytic genes that can bind to the viral genome and inhibit lytic genes as early as 4 hours post infection. Surprisingly, our ChIP analyses showed that RYBP binds to lytic viral gene promoters in a PRC1-independent manner, does not affect PRC1 activity on the KSHV genome, and can reduce the level of histone marks associated with transcription elongation. Our data also suggest that RYBP can repress the viral lytic cycle after primary infection by inhibiting the transcription elongation of the lytic cycle inducer KSHV gene RTA. Based on our results we propose that RYBP uses a PRC1-independent mechanism to block KSHV RTA expression thereby promoting the establishment of KSHV latency following de novo infection.
Collapse
|
2
|
Bölicke N, Albert M. Polycomb-mediated gene regulation in human brain development and neurodevelopmental disorders. Dev Neurobiol 2022; 82:345-363. [PMID: 35384339 DOI: 10.1002/dneu.22876] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Revised: 03/09/2022] [Accepted: 03/28/2022] [Indexed: 12/17/2022]
Abstract
The neocortex is considered the seat of higher cognitive function in humans. It develops from a sheet of neural progenitor cells, most of which eventually give rise to neurons. This process of cell fate determination is controlled by precise temporal and spatial gene expression patterns that in turn are affected by epigenetic mechanisms including Polycomb group (PcG) regulation. PcG proteins assemble in multiprotein complexes and catalyze repressive posttranslational histone modifications. Their association with neurodevelopmental disease and various types of cancer of the central nervous system, as well as observations in mouse models, has implicated these epigenetic modifiers in controlling various stages of cortex development. The precise mechanisms conveying PcG-associated transcriptional repression remain incompletely understood and are an active field of research. PcG activity appears to be highly context-specific, raising the question of species-specific differences in the regulation of neural stem and progenitor regulation. In this review, we will discuss our growing understanding of how PcG regulation affects human cortex development, based on studies in murine model systems, but focusing mostly on findings obtained from examining impaired PcG activity in the context of human neurodevelopmental disorders and cancer. Furthermore, we will highlight relevant experimental approaches for functional investigations of PcG regulation in human cortex development.
Collapse
Affiliation(s)
- Nora Bölicke
- Center for Regenerative Therapies Dresden, Technische Universität Dresden, Dresden, Germany
| | - Mareike Albert
- Center for Regenerative Therapies Dresden, Technische Universität Dresden, Dresden, Germany
| |
Collapse
|
3
|
Elsherbiny A, Dobreva G. Epigenetic memory of cell fate commitment. Curr Opin Cell Biol 2021; 69:80-87. [PMID: 33535129 DOI: 10.1016/j.ceb.2020.12.014] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Revised: 12/15/2020] [Accepted: 12/22/2020] [Indexed: 12/23/2022]
Abstract
During development, discrete cell fates are established in precise spatiotemporal order guided by morphogen signals. These signals converge in the nucleus to induce transcriptional and epigenetic programming that determines cell fate. Once cell identity is established, cell programs have to be accurately sustained through multiple rounds of cell division, during which DNA replication serves as a window of opportunity for altering cell fate. In this review, we summarize recent advances in understanding the molecular players that underlie epigenetic memory of cell fate decisions, with a particular focus on histone modifications and mitotic bookmarking factors. We also discuss the different mechanisms of inheritance of repressed and active chromatin states.
Collapse
Affiliation(s)
- Adel Elsherbiny
- Department of Anatomy and Developmental Biology, European Center for Angioscience (ECAS), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany; German Centre for Cardiovascular Research (DZHK), Germany
| | - Gergana Dobreva
- Department of Anatomy and Developmental Biology, European Center for Angioscience (ECAS), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany; German Centre for Cardiovascular Research (DZHK), Germany.
| |
Collapse
|
4
|
Wright H, Aylwin CF, Toro CA, Ojeda SR, Lomniczi A. Polycomb represses a gene network controlling puberty via modulation of histone demethylase Kdm6b expression. Sci Rep 2021; 11:1996. [PMID: 33479437 PMCID: PMC7819995 DOI: 10.1038/s41598-021-81689-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Accepted: 01/08/2021] [Indexed: 12/13/2022] Open
Abstract
Female puberty is subject to Polycomb Group (PcG)-dependent transcriptional repression. Kiss1, a puberty-activating gene, is a key target of this silencing mechanism. Using a gain-of-function approach and a systems biology strategy we now show that EED, an essential PcG component, acts in the arcuate nucleus of the hypothalamus to alter the functional organization of a gene network involved in the stimulatory control of puberty. A central node of this network is Kdm6b, which encodes an enzyme that erases the PcG-dependent histone modification H3K27me3. Kiss1 is a first neighbor in the network; genes encoding glutamatergic receptors and potassium channels are second neighbors. By repressing Kdm6b expression, EED increases H3K27me3 abundance at these gene promoters, reducing gene expression throughout a gene network controlling puberty activation. These results indicate that Kdm6b repression is a basic mechanism used by PcG to modulate the biological output of puberty-activating gene networks.
Collapse
Affiliation(s)
- Hollis Wright
- Division of Neuroscience, Oregon National Primate Research Center/OHSU, Beaverton, OR, USA
| | - Carlos F Aylwin
- Division of Neuroscience, Oregon National Primate Research Center/OHSU, Beaverton, OR, USA
| | - Carlos A Toro
- Division of Neuroscience, Oregon National Primate Research Center/OHSU, Beaverton, OR, USA
| | - Sergio R Ojeda
- Division of Neuroscience, Oregon National Primate Research Center/OHSU, Beaverton, OR, USA
| | - Alejandro Lomniczi
- Division of Neuroscience, Oregon National Primate Research Center/OHSU, Beaverton, OR, USA.
| |
Collapse
|
5
|
Locard‐Paulet M, Voisinne G, Froment C, Goncalves Menoita M, Ounoughene Y, Girard L, Gregoire C, Mori D, Martinez M, Luche H, Garin J, Malissen M, Burlet‐Schiltz O, Malissen B, Gonzalez de Peredo A, Roncagalli R. LymphoAtlas: a dynamic and integrated phosphoproteomic resource of TCR signaling in primary T cells reveals ITSN2 as a regulator of effector functions. Mol Syst Biol 2020; 16:e9524. [PMID: 32618424 PMCID: PMC7333348 DOI: 10.15252/msb.20209524] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Revised: 05/19/2020] [Accepted: 05/20/2020] [Indexed: 12/29/2022] Open
Abstract
T-cell receptor (TCR) ligation-mediated protein phosphorylation regulates the activation, cellular responses, and fates of T cells. Here, we used time-resolved high-resolution phosphoproteomics to identify, quantify, and characterize the phosphorylation dynamics of thousands of phosphorylation sites in primary T cells during the first 10 min after TCR stimulation. Bioinformatic analysis of the data revealed a coherent orchestration of biological processes underlying T-cell activation. In particular, functional modules associated with cytoskeletal remodeling, transcription, translation, and metabolic processes were mobilized within seconds after TCR engagement. Among proteins whose phosphorylation was regulated by TCR stimulation, we demonstrated, using a fast-track gene inactivation approach in primary lymphocytes, that the ITSN2 adaptor protein regulated T-cell effector functions. This resource, called LymphoAtlas, represents an integrated pipeline to further decipher the organization of the signaling network encoding T-cell activation. LymphoAtlas is accessible to the community at: https://bmm-lab.github.io/LymphoAtlas.
Collapse
Affiliation(s)
- Marie Locard‐Paulet
- Institut de Pharmacologie et de Biologie Structurale (IPBS)Université de Toulouse, CNRS, UPSToulouseFrance
- Present address:
Novo Nordisk Foundation Center for Protein ResearchUniversity of CopenhagenCopenhagenDenmark
| | - Guillaume Voisinne
- Centre d'Immunologie de Marseille‐LuminyINSERM, CNRSAix Marseille UniversitéMarseilleFrance
| | - Carine Froment
- Institut de Pharmacologie et de Biologie Structurale (IPBS)Université de Toulouse, CNRS, UPSToulouseFrance
| | | | - Youcef Ounoughene
- Centre d'Immunologie de Marseille‐LuminyINSERM, CNRSAix Marseille UniversitéMarseilleFrance
- Centre d'ImmunophénomiqueINSERM, CNRS UMRAix Marseille UniversitéMarseilleFrance
| | - Laura Girard
- Centre d'Immunologie de Marseille‐LuminyINSERM, CNRSAix Marseille UniversitéMarseilleFrance
- Centre d'ImmunophénomiqueINSERM, CNRS UMRAix Marseille UniversitéMarseilleFrance
| | - Claude Gregoire
- Centre d'Immunologie de Marseille‐LuminyINSERM, CNRSAix Marseille UniversitéMarseilleFrance
| | - Daiki Mori
- Centre d'Immunologie de Marseille‐LuminyINSERM, CNRSAix Marseille UniversitéMarseilleFrance
- Centre d'ImmunophénomiqueINSERM, CNRS UMRAix Marseille UniversitéMarseilleFrance
| | - Manuel Martinez
- Centre d'ImmunophénomiqueINSERM, CNRS UMRAix Marseille UniversitéMarseilleFrance
| | - Hervé Luche
- Centre d'ImmunophénomiqueINSERM, CNRS UMRAix Marseille UniversitéMarseilleFrance
| | - Jerôme Garin
- CEA, BIG, Biologie à Grande Echelle, INSERM, U1038Université Grenoble‐AlpesGrenobleFrance
| | - Marie Malissen
- Centre d'Immunologie de Marseille‐LuminyINSERM, CNRSAix Marseille UniversitéMarseilleFrance
- Centre d'ImmunophénomiqueINSERM, CNRS UMRAix Marseille UniversitéMarseilleFrance
| | - Odile Burlet‐Schiltz
- Institut de Pharmacologie et de Biologie Structurale (IPBS)Université de Toulouse, CNRS, UPSToulouseFrance
| | - Bernard Malissen
- Centre d'Immunologie de Marseille‐LuminyINSERM, CNRSAix Marseille UniversitéMarseilleFrance
- Centre d'ImmunophénomiqueINSERM, CNRS UMRAix Marseille UniversitéMarseilleFrance
| | - Anne Gonzalez de Peredo
- Institut de Pharmacologie et de Biologie Structurale (IPBS)Université de Toulouse, CNRS, UPSToulouseFrance
| | - Romain Roncagalli
- Centre d'Immunologie de Marseille‐LuminyINSERM, CNRSAix Marseille UniversitéMarseilleFrance
| |
Collapse
|
6
|
Weinman LM, Running KLD, Carey NS, Stevenson EJ, Swaney DL, Chow BY, Krogan NJ, Krogan NT. TCO, a Putative Transcriptional Regulator in Arabidopsis, Is a Target of the Protein Kinase CK2. Int J Mol Sci 2018; 20:ijms20010099. [PMID: 30597831 PMCID: PMC6337506 DOI: 10.3390/ijms20010099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Revised: 12/26/2018] [Accepted: 12/26/2018] [Indexed: 11/16/2022] Open
Abstract
As multicellular organisms grow, spatial and temporal patterns of gene expression are strictly regulated to ensure that developmental programs are invoked at appropriate stages. In this work, we describe a putative transcriptional regulator in Arabidopsis, TACO LEAF (TCO), whose overexpression results in the ectopic activation of reproductive genes during vegetative growth. Isolated as an activation-tagged allele, tco-1D displays gene misexpression and phenotypic abnormalities, such as curled leaves and early flowering, characteristic of chromatin regulatory mutants. A role for TCO in this mode of transcriptional regulation is further supported by the subnuclear accumulation patterns of TCO protein and genetic interactions between tco-1D and chromatin modifier mutants. The endogenous expression pattern of TCO and gene misregulation in tco loss-of-function mutants indicate that this factor is involved in seed development. We also demonstrate that specific serine residues of TCO protein are targeted by the ubiquitous kinase CK2. Collectively, these results identify TCO as a novel regulator of gene expression whose activity is likely influenced by phosphorylation, as is the case with many chromatin regulators.
Collapse
Affiliation(s)
- Laina M Weinman
- Department of Biology, American University, 4400 Massachusetts Avenue NW, Washington, DC 20016, USA.
| | - Katherine L D Running
- Department of Biology, American University, 4400 Massachusetts Avenue NW, Washington, DC 20016, USA.
| | - Nicholas S Carey
- Department of Biology, American University, 4400 Massachusetts Avenue NW, Washington, DC 20016, USA.
| | - Erica J Stevenson
- Gladstone Institute of Data Science and Biotechnology, J. David Gladstone Institutes, San Francisco, CA 94158, USA.
| | - Danielle L Swaney
- Gladstone Institute of Data Science and Biotechnology, J. David Gladstone Institutes, San Francisco, CA 94158, USA.
- Quantitative Biosciences Institute (QBI), University of California, San Francisco, CA 94158, USA.
| | - Brenda Y Chow
- Department of Biology, American University, 4400 Massachusetts Avenue NW, Washington, DC 20016, USA.
| | - Nevan J Krogan
- Gladstone Institute of Data Science and Biotechnology, J. David Gladstone Institutes, San Francisco, CA 94158, USA.
- Quantitative Biosciences Institute (QBI), University of California, San Francisco, CA 94158, USA.
| | - Naden T Krogan
- Department of Biology, American University, 4400 Massachusetts Avenue NW, Washington, DC 20016, USA.
| |
Collapse
|
7
|
Marasca F, Bodega B, Orlando V. How Polycomb-Mediated Cell Memory Deals With a Changing Environment. Bioessays 2018. [DOI: 10.1002/bies.201700137] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Federica Marasca
- Istituto Nazionale di Genetica Molecolare (INGM) “Romeo and Enrica Invernizzi”; Milan 20122 Italy
| | - Beatrice Bodega
- Istituto Nazionale di Genetica Molecolare (INGM) “Romeo and Enrica Invernizzi”; Milan 20122 Italy
| | - Valerio Orlando
- King Abdullah University of Science and Technology (KAUST); Environmental Epigenetics Research Program; Biological and Environmental Sciences and Engineering Division; Thuwal 23955-6900 Saudi Arabia
| |
Collapse
|
8
|
Di Costanzo A, Del Gaudio N, Conte L, Dell'Aversana C, Vermeulen M, de Thé H, Migliaccio A, Nebbioso A, Altucci L. The HDAC inhibitor SAHA regulates CBX2 stability via a SUMO-triggered ubiquitin-mediated pathway in leukemia. Oncogene 2018; 37:2559-2572. [PMID: 29467492 PMCID: PMC5945585 DOI: 10.1038/s41388-018-0143-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Revised: 12/15/2017] [Accepted: 12/24/2017] [Indexed: 12/31/2022]
Abstract
Polycomb group (PcG) proteins regulate transcription, playing a key role in stemness and differentiation. Deregulation of PcG members is known to be involved in cancer pathogenesis. Emerging evidence suggests that CBX2, a member of the PcG protein family, is overexpressed in several human tumors, correlating with lower overall survival. Unraveling the mechanisms regulating CBX2 expression may thus provide a promising new target for anticancer strategies. Here we show that the HDAC inhibitor SAHA regulates CBX2 stability via a SUMO-triggered ubiquitin-mediated pathway in leukemia. We identify CBX4 and RNF4 as the E3 SUMO and E3 ubiquitin ligase, respectively, and describe the specific molecular mechanism regulating CBX2 protein stability. Finally, we show that CBX2-depleted leukemic cells display impaired proliferation, underscoring its critical role in regulating leukemia cell tumorogenicity. Our results show that SAHA affects CBX2 stability, revealing a potential SAHA-mediated anti-leukemic activity though SUMO2/3 pathway.
Collapse
Affiliation(s)
- Antonella Di Costanzo
- Department of Biochemistry, Biophysics and General Pathology, University of Campania "Luigi Vanvitelli", Vico L. De Crecchio 7, 80138, Napoli, Italy.
| | - Nunzio Del Gaudio
- Department of Biochemistry, Biophysics and General Pathology, University of Campania "Luigi Vanvitelli", Vico L. De Crecchio 7, 80138, Napoli, Italy
| | - Lidio Conte
- Department of Biochemistry, Biophysics and General Pathology, University of Campania "Luigi Vanvitelli", Vico L. De Crecchio 7, 80138, Napoli, Italy
| | - Carmela Dell'Aversana
- Department of Biochemistry, Biophysics and General Pathology, University of Campania "Luigi Vanvitelli", Vico L. De Crecchio 7, 80138, Napoli, Italy
| | - Michiel Vermeulen
- Department of Molecular Biology, Faculty of Science, Radboud Institute for Molecular Life Sciences, Radboud University, 6500 HB, Nijmegen, The Netherlands
| | - Hugues de Thé
- INSERM Unite ́ Mixte de Recherche 944, Equipe labellisée par la Ligue Nationale contre le Cancer, Institut Universitaire d'Hématologie, Hôpital St. Louis, Paris Cedex 10, France
| | - Antimo Migliaccio
- Department of Biochemistry, Biophysics and General Pathology, University of Campania "Luigi Vanvitelli", Vico L. De Crecchio 7, 80138, Napoli, Italy
| | - Angela Nebbioso
- Department of Biochemistry, Biophysics and General Pathology, University of Campania "Luigi Vanvitelli", Vico L. De Crecchio 7, 80138, Napoli, Italy
| | - Lucia Altucci
- Department of Biochemistry, Biophysics and General Pathology, University of Campania "Luigi Vanvitelli", Vico L. De Crecchio 7, 80138, Napoli, Italy.
| |
Collapse
|
9
|
PRC1 Prevents Replication Stress during Chondrogenic Transit Amplification. EPIGENOMES 2017. [DOI: 10.3390/epigenomes1030022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
|
10
|
Schuettengruber B, Bourbon HM, Di Croce L, Cavalli G. Genome Regulation by Polycomb and Trithorax: 70 Years and Counting. Cell 2017; 171:34-57. [DOI: 10.1016/j.cell.2017.08.002] [Citation(s) in RCA: 611] [Impact Index Per Article: 87.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Revised: 07/17/2017] [Accepted: 08/01/2017] [Indexed: 01/05/2023]
|
11
|
Du J, Zhang J, He T, Li Y, Su Y, Tie F, Liu M, Harte PJ, Zhu AJ. Stuxnet Facilitates the Degradation of Polycomb Protein during Development. Dev Cell 2017; 37:507-19. [PMID: 27326929 DOI: 10.1016/j.devcel.2016.05.013] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Revised: 04/29/2016] [Accepted: 05/18/2016] [Indexed: 10/21/2022]
Abstract
Polycomb-group (PcG) proteins function to ensure correct deployment of developmental programs by epigenetically repressing target gene expression. Despite the importance, few studies have been focused on the regulation of PcG activity itself. Here, we report a Drosophila gene, stuxnet (stx), that controls Pc protein stability. We find that heightened stx activity leads to homeotic transformation, reduced Pc activity, and de-repression of PcG targets. Conversely, stx mutants, which can be rescued by decreased Pc expression, display developmental defects resembling hyperactivation of Pc. Our biochemical analyses provide a mechanistic basis for the interaction between stx and Pc; Stx facilitates Pc degradation in the proteasome, independent of ubiquitin modification. Furthermore, this mode of regulation is conserved in vertebrates. Mouse stx promotes degradation of Cbx4, an orthologous Pc protein, in vertebrate cells and induces homeotic transformation in Drosophila. Our results highlight an evolutionarily conserved mechanism of regulated protein degradation on PcG homeostasis and epigenetic activity.
Collapse
Affiliation(s)
- Juan Du
- State Key Laboratory of Membrane Biology, Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Peking University, Beijing 100871, China; Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
| | - Junzheng Zhang
- State Key Laboratory of Membrane Biology, Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Peking University, Beijing 100871, China; Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
| | - Tao He
- State Key Laboratory of Membrane Biology, Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Peking University, Beijing 100871, China
| | - Yajuan Li
- State Key Laboratory of Membrane Biology, Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Peking University, Beijing 100871, China
| | - Ying Su
- State Key Laboratory of Membrane Biology, Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Peking University, Beijing 100871, China
| | - Feng Tie
- Department of Genetics and Genome Sciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Min Liu
- State Key Laboratory of Membrane Biology, Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Peking University, Beijing 100871, China; Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
| | - Peter J Harte
- Department of Genetics and Genome Sciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Alan Jian Zhu
- State Key Laboratory of Membrane Biology, Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Peking University, Beijing 100871, China; Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China.
| |
Collapse
|
12
|
Genome-wide chemical mapping of O-GlcNAcylated proteins in Drosophila melanogaster. Nat Chem Biol 2016; 13:161-167. [PMID: 27918560 DOI: 10.1038/nchembio.2247] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Accepted: 09/15/2016] [Indexed: 12/28/2022]
Abstract
N-Acetylglucosamine β-O-linked to nucleocytoplasmic proteins (O-GlcNAc) is implicated in the regulation of gene expression in organisms, from humans to Drosophila melanogaster. Within Drosophila, O-GlcNAc transferase (OGT) is one of the Polycomb group proteins (PcGs) that act through Polycomb group response elements (PREs) to silence homeotic (HOX) and other PcG target genes. Using Drosophila, we identify new O-GlcNAcylated PcG proteins and develop an antibody-free metabolic feeding approach to chemoselectively map genomic loci enriched in O-GlcNAc using next-generation sequencing. We find that O-GlcNAc is distributed to specific genomic loci both in cells and in vivo. Many of these loci overlap with PREs, but O-GlcNAc is also present at other loci lacking PREs. Loss of OGT leads to altered gene expression not only at loci containing PREs but also at loci lacking PREs, including several heterochromatic genes. These data suggest that O-GlcNAc acts through multiple mechanisms to regulate gene expression in Drosophila.
Collapse
|
13
|
Wu X. Stuxnet detected, Pc breaks down. SCIENCE CHINA-LIFE SCIENCES 2016; 59:1202-1203. [PMID: 27468756 DOI: 10.1007/s11427-016-5108-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2016] [Accepted: 07/02/2016] [Indexed: 10/21/2022]
Affiliation(s)
- Xudong Wu
- Department of Cell Biology, 2011 Collaborative Innovation Center of Tianjin for Medical Epigenetics, Tianjin Key Laboratory of Medical Epigenetics, Tianjin Medical University, Tianjin, 300070, China.
| |
Collapse
|
14
|
Change of epigenetic modification and human reproduction. ASIAN PACIFIC JOURNAL OF REPRODUCTION 2016. [DOI: 10.1016/j.apjr.2015.12.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
|
15
|
The quest for mammalian Polycomb response elements: are we there yet? Chromosoma 2015; 125:471-96. [PMID: 26453572 PMCID: PMC4901126 DOI: 10.1007/s00412-015-0539-4] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Revised: 08/31/2015] [Accepted: 09/02/2015] [Indexed: 12/12/2022]
Abstract
A long-standing mystery in the field of Polycomb and Trithorax regulation is how these proteins, which are highly conserved between flies and mammals, can regulate several hundred equally highly conserved target genes, but recognise these targets via cis-regulatory elements that appear to show no conservation in their DNA sequence. These elements, termed Polycomb/Trithorax response elements (PRE/TREs or PREs), are relatively well characterised in flies, but their mammalian counterparts have proved to be extremely difficult to identify. Recent progress in this endeavour has generated a wealth of data and raised several intriguing questions. Here, we ask why and to what extent mammalian PREs are so different to those of the fly. We review recent advances, evaluate current models and identify open questions in the quest for mammalian PREs.
Collapse
|
16
|
MK3 modulation affects BMI1-dependent and independent cell cycle check-points. PLoS One 2015; 10:e0118840. [PMID: 25853770 PMCID: PMC4390245 DOI: 10.1371/journal.pone.0118840] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2013] [Accepted: 01/14/2015] [Indexed: 01/04/2023] Open
Abstract
Although the MK3 gene was originally found deleted in some cancers, it is highly expressed in others. The relevance of MK3 for oncogenesis is currently not clear. We recently reported that MK3 controls ERK activity via a negative feedback mechanism. This prompted us to investigate a potential role for MK3 in cell proliferation. We here show that overexpression of MK3 induces a proliferative arrest in normal diploid human fibroblasts, characterized by enhanced expression of replication stress- and senescence-associated markers. Surprisingly, MK3 depletion evokes similar senescence characteristics in the fibroblast model. We previously identified MK3 as a binding partner of Polycomb Repressive Complex 1 (PRC1) proteins. In the current study we show that MK3 overexpression results in reduced cellular EZH2 levels and concomitant loss of epigenetic H3K27me3-marking and PRC1/chromatin-occupation at the CDKN2A/INK4A locus. In agreement with this, the PRC1 oncoprotein BMI1, but not the PCR2 protein EZH2, bypasses MK3-induced senescence in fibroblasts and suppresses P16INK4A expression. In contrast, BMI1 does not rescue the MK3 loss-of-function phenotype, suggesting the involvement of multiple different checkpoints in gain and loss of MK3 function. Notably, MK3 ablation enhances proliferation in two different cancer cells. Finally, the fibroblast model was used to evaluate the effect of potential tumorigenic MK3 driver-mutations on cell proliferation and M/SAPK signaling imbalance. Taken together, our findings support a role for MK3 in control of proliferation and replicative life-span, in part through concerted action with BMI1, and suggest that the effect of MK3 modulation or mutation on M/SAPK signaling and, ultimately, proliferation, is cell context-dependent.
Collapse
|
17
|
Steffen PA, Ringrose L. What are memories made of? How Polycomb and Trithorax proteins mediate epigenetic memory. Nat Rev Mol Cell Biol 2014; 15:340-56. [PMID: 24755934 DOI: 10.1038/nrm3789] [Citation(s) in RCA: 249] [Impact Index Per Article: 24.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
In any biological system with memory, the state of the system depends on its history. Epigenetic memory maintains gene expression states through cell generations without a change in DNA sequence and in the absence of initiating signals. It is immensely powerful in biological systems - it adds long-term stability to gene expression states and increases the robustness of gene regulatory networks. The Polycomb group (PcG) and Trithorax group (TrxG) proteins can confer long-term, mitotically heritable memory by sustaining silent and active gene expression states, respectively. Several recent studies have advanced our understanding of the molecular mechanisms of this epigenetic memory during DNA replication and mitosis.
Collapse
Affiliation(s)
- Philipp A Steffen
- Institute of Molecular Biotechnology (IMBA), Dr. Bohr-Gasse 3, 1030 Vienna, Austria
| | - Leonie Ringrose
- Institute of Molecular Biotechnology (IMBA), Dr. Bohr-Gasse 3, 1030 Vienna, Austria
| |
Collapse
|
18
|
Campbell PA, Rudnicki MA. Oct4 interaction with Hmgb2 regulates Akt signaling and pluripotency. Stem Cells 2014; 31:1107-20. [PMID: 23495099 DOI: 10.1002/stem.1365] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2012] [Revised: 01/26/2013] [Accepted: 01/31/2013] [Indexed: 12/20/2022]
Abstract
In pluripotent stem cells, bivalent domains mark the promoters of developmentally regulated loci. Histones in these chromatin regions contain coincident epigenetic modifications of gene activation and repression. How these marks are transmitted to maintain the pluripotent state in daughter progeny remains poorly understood. Our study demonstrates that Oct4 post-translational modifications (PTMs) form a positive feedback loop, which promotes Akt activation and interaction with Hmgb2 and the SET complex. This preserves H3K27me3 modifications in daughter progeny and maintains the pluripotent gene expression signature in murine embryonic stem cells. However, if Oct4 is not phosphorylated, a negative feedback loop is formed that inactivates Akt and initiates the DNA damage response. Oct4 sumoylation then is required for G1/S progression and transmission of the repressive H3K27me3 mark. Therefore, PTMs regulate the ability of Oct4 to direct the spatio-temporal formation of activating and repressing complexes to orchestrate chromatin plasticity and pluripotency. Our work highlights a previously unappreciated role for Oct4 PTM-dependent interactions in maintaining restrained Akt signaling and promoting a primitive epigenetic state.
Collapse
Affiliation(s)
- Pearl A Campbell
- Sprott Centre for Stem Cell Research, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
| | | |
Collapse
|
19
|
Kolybaba A, Classen AK. Sensing cellular states--signaling to chromatin pathways targeting Polycomb and Trithorax group function. Cell Tissue Res 2014; 356:477-93. [PMID: 24728925 DOI: 10.1007/s00441-014-1824-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2013] [Accepted: 01/22/2014] [Indexed: 02/06/2023]
Abstract
Cells respond to extra- and intra-cellular signals by dynamically changing their gene expression patterns. After termination of the original signal, new expression patterns are maintained by epigenetic DNA and histone modifications. This represents a powerful mechanism that enables long-term phenotypic adaptation to transient signals. Adaptation of epigenetic landscapes is important for mediating cellular differentiation during development and allows adjustment to altered environmental conditions throughout life. Work over the last decade has begun to elucidate the way that extra- and intra-cellular signals lead to changes in gene expression patterns by directly modulating the function of chromatin-associated proteins. Here, we review key signaling-to-chromatin pathways that are specifically thought to target Polycomb and Trithorax group complexes, a classic example of epigenetically acting gene silencers and activators important in development, stem cell differentiation and cancer. We discuss the influence that signals triggered by kinase cascades, metabolic fluctuations and cell-cycle dynamics have on the function of these protein complexes. Further investigation into these pathways will be important for understanding the mechanisms that maintain epigenetic stability and those that promote epigenetic plasticity.
Collapse
Affiliation(s)
- Addie Kolybaba
- Ludwig Maximilians University Munich, Faculty of Biology, Grosshaderner Strasse 2-4, 82152, Planegg-Martinsried, Germany
| | | |
Collapse
|
20
|
Aberrant DNA methylation in human cancers. ACTA ACUST UNITED AC 2013; 33:798-804. [PMID: 24337838 DOI: 10.1007/s11596-013-1201-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2013] [Revised: 11/15/2013] [Indexed: 12/13/2022]
Abstract
DNA methylation, one of the best-characterized epigenetic modifications, plays essential roles in diseases, including human cancers. In recent years, our understanding on DNA methylation with human cancers has made significant progress, which was facilitated by stunning development in the analysis of the human methylome of multiple cancer types. In this review, recent developments in the characterization of aberrant DNA methylation involved in human cancers development were discussed with special emphasis on the mechanisms of aberrant DNA methylation in human cancers. We also summarize the recent treatment strategy for human cancers with de-methylation drugs.
Collapse
|
21
|
Wu HA, Balsbaugh JL, Chandler H, Georgilis A, Zullow H, Shabanowitz J, Hunt DF, Gil J, Peters G, Bernstein E. Mitogen-activated protein kinase signaling mediates phosphorylation of polycomb ortholog Cbx7. J Biol Chem 2013; 288:36398-408. [PMID: 24194518 DOI: 10.1074/jbc.m113.486266] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Cbx7 is one of five mammalian orthologs of the Drosophila Polycomb. Cbx7 recognizes methylated lysine residues on the histone H3 tail and contributes to gene silencing in the context of the Polycomb repressive complex 1 (PRC1). However, our knowledge of Cbx7 post-translational modifications remains limited. Through combined biochemical and mass spectrometry approaches, we report a novel phosphorylation site on mouse Cbx7 at residue Thr-118 (Cbx7T118ph), near the highly conserved Polycomb box. The generation of a site-specific antibody to Cbx7T118ph demonstrates that Cbx7 is phosphorylated via MAPK signaling. Furthermore, we find Cbx7T118 phosphorylation in murine mammary carcinoma cells, which can be blocked by MEK inhibitors. Upon EGF stimulation, Cbx7 interacts robustly with other members of PRC1. To test the role of Cbx7T118 phosphorylation in gene silencing, we employed a RAS-induced senescence model system. We demonstrate that Cbx7T118 phosphorylation moderately enhances repression of its target gene p16. In summary, we have identified and characterized a novel MAPK-mediated phosphorylation site on Cbx7 and propose that mitogen signaling to the chromatin template regulates PRC1 function.
Collapse
Affiliation(s)
- Hsan-au Wu
- From the Department of Oncological Sciences and
| | | | | | | | | | | | | | | | | | | |
Collapse
|
22
|
Šmigová J, Juda P, Bártová E, Raška I. Dynamics of Polycomb chromatin domains under conditions of increased molecular crowding. Biol Cell 2013; 105:519-34. [DOI: 10.1111/boc.201300022] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2013] [Accepted: 08/07/2013] [Indexed: 01/08/2023]
Affiliation(s)
- Jana Šmigová
- Charles University in Prague; First Faculty of Medicine; Institute of Cellular Biology and Pathology; Czech Republic
| | - Pavel Juda
- Charles University in Prague; First Faculty of Medicine; Institute of Cellular Biology and Pathology; Czech Republic
| | - Eva Bártová
- Institute of Biophysics; Academy of Sciences of the Czech Republic, v.v.i; Brno Czech Republic
| | - Ivan Raška
- Charles University in Prague; First Faculty of Medicine; Institute of Cellular Biology and Pathology; Czech Republic
| |
Collapse
|
23
|
Bhowmick P, Pancsa R, Guharoy M, Tompa P. Functional diversity and structural disorder in the human ubiquitination pathway. PLoS One 2013; 8:e65443. [PMID: 23734257 PMCID: PMC3667038 DOI: 10.1371/journal.pone.0065443] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2013] [Accepted: 04/24/2013] [Indexed: 02/04/2023] Open
Abstract
The ubiquitin-proteasome system plays a central role in cellular regulation and protein quality control (PQC). The system is built as a pyramid of increasing complexity, with two E1 (ubiquitin activating), few dozen E2 (ubiquitin conjugating) and several hundred E3 (ubiquitin ligase) enzymes. By collecting and analyzing E3 sequences from the KEGG BRITE database and literature, we assembled a coherent dataset of 563 human E3s and analyzed their various physical features. We found an increase in structural disorder of the system with multiple disorder predictors (IUPred – E1: 5.97%, E2: 17.74%, E3: 20.03%). E3s that can bind E2 and substrate simultaneously (single subunit E3, ssE3) have significantly higher disorder (22.98%) than E3s in which E2 binding (multi RING-finger, mRF, 0.62%), scaffolding (6.01%) and substrate binding (adaptor/substrate recognition subunits, 17.33%) functions are separated. In ssE3s, the disorder was localized in the substrate/adaptor binding domains, whereas the E2-binding RING/HECT-domains were structured. To demonstrate the involvement of disorder in E3 function, we applied normal modes and molecular dynamics analyses to show how a disordered and highly flexible linker in human CBL (an E3 that acts as a regulator of several tyrosine kinase-mediated signalling pathways) facilitates long-range conformational changes bringing substrate and E2-binding domains towards each other and thus assisting in ubiquitin transfer. E3s with multiple interaction partners (as evidenced by data in STRING) also possess elevated levels of disorder (hubs, 22.90% vs. non-hubs, 18.36%). Furthermore, a search in PDB uncovered 21 distinct human E3 interactions, in 7 of which the disordered region of E3s undergoes induced folding (or mutual induced folding) in the presence of the partner. In conclusion, our data highlights the primary role of structural disorder in the functions of E3 ligases that manifests itself in the substrate/adaptor binding functions as well as the mechanism of ubiquitin transfer by long-range conformational transitions.
Collapse
Affiliation(s)
- Pallab Bhowmick
- VIB Department of Structural Biology, Vrije Universiteit Brussel, Brussels, Belgium
| | - Rita Pancsa
- VIB Department of Structural Biology, Vrije Universiteit Brussel, Brussels, Belgium
| | - Mainak Guharoy
- VIB Department of Structural Biology, Vrije Universiteit Brussel, Brussels, Belgium
| | - Peter Tompa
- VIB Department of Structural Biology, Vrije Universiteit Brussel, Brussels, Belgium
- Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary
- * E-mail:
| |
Collapse
|
24
|
Steffen PA, Fonseca JP, Gänger C, Dworschak E, Kockmann T, Beisel C, Ringrose L. Quantitative in vivo analysis of chromatin binding of Polycomb and Trithorax group proteins reveals retention of ASH1 on mitotic chromatin. Nucleic Acids Res 2013; 41:5235-50. [PMID: 23580551 PMCID: PMC3664806 DOI: 10.1093/nar/gkt217] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The Polycomb (PcG) and Trithorax (TrxG) group proteins work antagonistically on several hundred developmentally important target genes, giving stable mitotic memory, but also allowing flexibility of gene expression states. How this is achieved in quantitative terms is poorly understood. Here, we present a quantitative kinetic analysis in living Drosophila of the PcG proteins Enhancer of Zeste, (E(Z)), Pleiohomeotic (PHO) and Polycomb (PC) and the TrxG protein absent, small or homeotic discs 1 (ASH1). Fluorescence recovery after photobleaching and fluorescence correlation spectroscopy reveal highly dynamic chromatin binding behaviour for all proteins, with exchange occurring within seconds. We show that although the PcG proteins substantially dissociate from mitotic chromatin, ASH1 remains robustly associated with chromatin throughout mitosis. Finally, we show that chromatin binding by ASH1 and PC switches from an antagonistic relationship in interphase, to a cooperative one during mitosis. These results provide quantitative insights into PcG and TrxG chromatin-binding dynamics and have implications for our understanding of the molecular nature of epigenetic memory.
Collapse
Affiliation(s)
- Philipp A Steffen
- Institute of Molecular Biotechnology, Dr Bohr-Gasse 3, 1030 Vienna, Austria
| | | | | | | | | | | | | |
Collapse
|
25
|
Spaapen F, van den Akker GGH, Caron MMJ, Prickaerts P, Rofel C, Dahlmans VEH, Surtel DAM, Paulis Y, Schweizer F, Welting TJM, Eijssen LM, Voncken JW. The immediate early gene product EGR1 and polycomb group proteins interact in epigenetic programming during chondrogenesis. PLoS One 2013; 8:e58083. [PMID: 23483971 PMCID: PMC3590300 DOI: 10.1371/journal.pone.0058083] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2012] [Accepted: 01/30/2013] [Indexed: 12/18/2022] Open
Abstract
Initiation of and progression through chondrogenesis is driven by changes in the cellular microenvironment. At the onset of chondrogenesis, resting mesenchymal stem cells are mobilized in vivo and a complex, step-wise chondrogenic differentiation program is initiated. Differentiation requires coordinated transcriptomic reprogramming and increased progenitor proliferation; both processes require chromatin remodeling. The nature of early molecular responses that relay differentiation signals to chromatin is poorly understood. We here show that immediate early genes are rapidly and transiently induced in response to differentiation stimuli in vitro. Functional ablation of the immediate early factor EGR1 severely deregulates expression of key chondrogenic control genes at the onset of differentiation. In addition, differentiating cells accumulate DNA damage, activate a DNA damage response and undergo a cell cycle arrest and prevent differentiation associated hyper-proliferation. Failed differentiation in the absence of EGR1 affects global acetylation and terminates in overall histone hypermethylation. We report novel molecular connections between EGR1 and Polycomb Group function: Polycomb associated histone H3 lysine27 trimethylation (H3K27me3) blocks chromatin access of EGR1. In addition, EGR1 ablation results in abnormal Ezh2 and Bmi1 expression. Consistent with this functional interaction, we identify a number of co-regulated targets genes in a chondrogenic gene network. We here describe an important role for EGR1 in early chondrogenic epigenetic programming to accommodate early gene-environment interactions in chondrogenesis.
Collapse
Affiliation(s)
- Frank Spaapen
- Department of Molecular Genetics, Maastricht University Medical Centre, Maastricht, The Netherlands
| | - Guus G. H. van den Akker
- Department of Molecular Genetics, Maastricht University Medical Centre, Maastricht, The Netherlands
| | - Marjolein M. J. Caron
- Department of Orthopaedic Surgery, Maastricht University Medical Centre, Maastricht, The Netherlands
| | - Peggy Prickaerts
- Department of Molecular Genetics, Maastricht University Medical Centre, Maastricht, The Netherlands
| | - Celine Rofel
- Department of Molecular Genetics, Maastricht University Medical Centre, Maastricht, The Netherlands
| | - Vivian E. H. Dahlmans
- Department of Molecular Genetics, Maastricht University Medical Centre, Maastricht, The Netherlands
| | - Don A. M. Surtel
- Department of Orthopaedic Surgery, Maastricht University Medical Centre, Maastricht, The Netherlands
| | - Yvette Paulis
- Department of Molecular Genetics, Maastricht University Medical Centre, Maastricht, The Netherlands
| | - Finja Schweizer
- Department of Orthopaedic Surgery, Maastricht University Medical Centre, Maastricht, The Netherlands
| | - Tim J. M. Welting
- Department of Orthopaedic Surgery, Maastricht University Medical Centre, Maastricht, The Netherlands
| | - Lars M. Eijssen
- Department of Bioinformatics – BiGCaT, Maastricht University Medical Centre, Maastricht, The Netherlands
| | - Jan Willem Voncken
- Department of Molecular Genetics, Maastricht University Medical Centre, Maastricht, The Netherlands
- * E-mail:
| |
Collapse
|
26
|
Bartke T, Borgel J, DiMaggio PA. Proteomics in epigenetics: new perspectives for cancer research. Brief Funct Genomics 2013; 12:205-18. [PMID: 23401080 PMCID: PMC3662889 DOI: 10.1093/bfgp/elt002] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
The involvement of epigenetic processes in the origin and progression of cancer is now widely appreciated. Consequently, targeting the enzymatic machinery that controls the epigenetic regulation of the genome has emerged as an attractive new strategy for therapeutic intervention. The development of epigenetic drugs requires a detailed knowledge of the processes that govern chromatin regulation. Over the recent years, mass spectrometry (MS) has become an indispensable tool in epigenetics research. In this review, we will give an overview of the applications of MS-based proteomics in studying various aspects of chromatin biology. We will focus on the use of MS in the discovery and mapping of histone modifications and how novel proteomic approaches are being utilized to identify and study chromatin-associated proteins and multi-subunit complexes. Finally, we will discuss the application of proteomic methods in the diagnosis and prognosis of cancer based on epigenetic biomarkers and comment on their future impact on cancer epigenetics.
Collapse
Affiliation(s)
- Till Bartke
- MRC Clinical Sciences Centre, Imperial College London Faculty of Medicine, Hammersmith Hospital Campus, London W12 0NN, UK.
| | | | | |
Collapse
|
27
|
Prickaerts P, Niessen HE, Mouchel-Vielh E, Dahlmans VE, van den Akker GG, Geijselaers C, Adriaens ME, Spaapen F, Takihara Y, Rapp UR, Peronnet F, Voncken JW. MK3 controls Polycomb target gene expression via negative feedback on ERK. Epigenetics Chromatin 2012; 5:12. [PMID: 22870894 PMCID: PMC3499388 DOI: 10.1186/1756-8935-5-12] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2012] [Accepted: 07/11/2012] [Indexed: 01/04/2023] Open
Abstract
Background Gene-environment interactions are mediated by epigenetic mechanisms. Polycomb Group proteins constitute part of an epigenetic cellular transcriptional memory system that is subject to dynamic modulation during differentiation. Molecular insight in processes that control dynamic chromatin association and dissociation of Polycomb repressive complexes during and beyond development is limited. We recently showed that MK3 interacts with Polycomb repressive complex 1 (PRC1). The functional relevance of this interaction, however, remained poorly understood. MK3 is activated downstream of mitogen- and stress-activated protein kinases (M/SAPKs), all of which fulfill crucial roles during development. We here use activation of the immediate-early response gene ATF3, a bona fide PRC1 target gene, as a model to study how MK3 and its effector kinases MAPK/ERK and SAPK/P38 are involved in regulation of PRC1-dependent ATF3 transcription. Results Our current data show that mitogenic signaling through ERK, P38 and MK3 regulates ATF3 expression by PRC1/chromatin dissociation and epigenetic modulation. Mitogenic stimulation results in transient P38-dependent H3S28 phosphorylation and ERK-driven PRC1/chromatin dissociation at PRC1 targets. H3S28 phosphorylation by itself appears not sufficient to induce PRC1/chromatin dissociation, nor ATF3 transcription, as inhibition of MEK/ERK signaling blocks BMI1/chromatin dissociation and ATF3 expression, despite induced H3S28 phosphorylation. In addition, we establish that concomitant loss of local H3K27me3 promoter marking is not required for ATF3 activation. We identify pERK as a novel signaling-induced binding partner of PRC1, and provide evidence that MK3 controls ATF3 expression in cultured cells via negative regulatory feedback on M/SAPKs. Dramatically increased ectopic wing vein formation in the absence of Drosophila MK in a Drosophila ERK gain-of-function wing vein patterning model, supports the existence of MK-mediated negative feedback regulation on pERK. Conclusion We here identify and characterize important actors in a PRC1-dependent epigenetic signal/response mechanism, some of which appear to be nonspecific global responses, whereas others provide modular specificity. Our findings provide novel insight into a Polycomb-mediated epigenetic mechanism that dynamically controls gene transcription and support a direct link between PRC1 and cellular responses to changes in the microenvironment.
Collapse
Affiliation(s)
- Peggy Prickaerts
- Department of Molecular Genetics, GROW School for Oncology and Developmental Biology, Maastricht University, Universiteitssingel 50, 6229ER, Maastricht, The Netherlands.,Laboratoire de Biologie du Développement UMR 7622, Centre National de la Recherche Scientifique, Université Pierre et Marie Curie-Paris 6, 9 Quai Saint-Bernard, 75005, Paris, France
| | - Hanneke Ec Niessen
- Department of Molecular Genetics, GROW School for Oncology and Developmental Biology, Maastricht University, Universiteitssingel 50, 6229ER, Maastricht, The Netherlands
| | - Emmanuèle Mouchel-Vielh
- Laboratoire de Biologie du Développement UMR 7622, Centre National de la Recherche Scientifique, Université Pierre et Marie Curie-Paris 6, 9 Quai Saint-Bernard, 75005, Paris, France
| | - Vivian Eh Dahlmans
- Department of Molecular Genetics, GROW School for Oncology and Developmental Biology, Maastricht University, Universiteitssingel 50, 6229ER, Maastricht, The Netherlands
| | - Guus Gh van den Akker
- Department of Molecular Genetics, GROW School for Oncology and Developmental Biology, Maastricht University, Universiteitssingel 50, 6229ER, Maastricht, The Netherlands
| | - Claudia Geijselaers
- Department of Molecular Genetics, GROW School for Oncology and Developmental Biology, Maastricht University, Universiteitssingel 50, 6229ER, Maastricht, The Netherlands
| | - Michiel E Adriaens
- BiGCaT Bioinformatics, Maastricht University, Universiteitssingel 50, 6229ER, Maastricht, The Netherlands
| | - Frank Spaapen
- Department of Molecular Genetics, GROW School for Oncology and Developmental Biology, Maastricht University, Universiteitssingel 50, 6229ER, Maastricht, The Netherlands
| | - Yoshihiro Takihara
- Department of Stem Cell Biology, Research Institute for Radiation Biology and Medicine, Hiroshima University, 1-2-3, Kasumi, Minami-ku, Hiroshima, Japan
| | - Ulf R Rapp
- Department of Molecular Biology, Max Planck Institute of Biochemistry, Am Klopferspitz 18, D-82152, Martinsried, Germany
| | - Frédérique Peronnet
- Laboratoire de Biologie du Développement UMR 7622, Centre National de la Recherche Scientifique, Université Pierre et Marie Curie-Paris 6, 9 Quai Saint-Bernard, 75005, Paris, France
| | - Jan Willem Voncken
- Department of Molecular Genetics, GROW School for Oncology and Developmental Biology, Maastricht University, Universiteitssingel 50, 6229ER, Maastricht, The Netherlands
| |
Collapse
|
28
|
Fonseca JP, Steffen PA, Müller S, Lu J, Sawicka A, Seiser C, Ringrose L. In vivo Polycomb kinetics and mitotic chromatin binding distinguish stem cells from differentiated cells. Genes Dev 2012; 26:857-71. [PMID: 22508729 DOI: 10.1101/gad.184648.111] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Epigenetic memory mediated by Polycomb group (PcG) proteins must be maintained during cell division, but must also be flexible to allow cell fate transitions. Here we quantify dynamic chromatin-binding properties of PH::GFP and PC::GFP in living Drosophila in two cell types that undergo defined differentiation and mitosis events. Quantitative fluorescence recovery after photobleaching (FRAP) analysis demonstrates that PcG binding has a higher plasticity in stem cells than in more determined cells and identifies a fraction of PcG proteins that binds mitotic chromatin with up to 300-fold longer residence times than in interphase. Mathematical modeling examines which parameters best distinguish stem cells from differentiated cells. We identify phosphorylation of histone H3 at Ser 28 as a potential mechanism governing the extent and rate of mitotic PC dissociation in different lineages. We propose that regulation of the kinetic properties of PcG-chromatin binding is an essential factor in the choice between stability and flexibility in the establishment of cell identities.
Collapse
|
29
|
Nacerddine K, Beaudry JB, Ginjala V, Westerman B, Mattiroli F, Song JY, van der Poel H, Ponz OB, Pritchard C, Cornelissen-Steijger P, Zevenhoven J, Tanger E, Sixma TK, Ganesan S, van Lohuizen M. Akt-mediated phosphorylation of Bmi1 modulates its oncogenic potential, E3 ligase activity, and DNA damage repair activity in mouse prostate cancer. J Clin Invest 2012; 122:1920-32. [PMID: 22505453 DOI: 10.1172/jci57477] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2011] [Accepted: 02/29/2012] [Indexed: 11/17/2022] Open
Abstract
Prostate cancer (PCa) is a major lethal malignancy in men, but the molecular events and their interplay underlying prostate carcinogenesis remain poorly understood. Epigenetic events and the upregulation of polycomb group silencing proteins including Bmi1 have been described to occur during PCa progression. Here, we found that conditional overexpression of Bmi1 in mice induced prostatic intraepithelial neoplasia, and elicited invasive adenocarcinoma when combined with PTEN haploinsufficiency. In addition, Bmi1 and the PI3K/Akt pathway were coactivated in a substantial fraction of human high-grade tumors. We found that Akt mediated Bmi1 phosphorylation, enhancing its oncogenic potential in an Ink4a/Arf-independent manner. This process also modulated the DNA damage response and affected genomic stability. Together, our findings demonstrate the etiological role of Bmi1 in PCa, unravel an oncogenic collaboration between Bmi1 and the PI3K/Akt pathway, and provide mechanistic insights into the modulation of Bmi1 function by phosphorylation during prostate carcinogenesis.
Collapse
Affiliation(s)
- Karim Nacerddine
- Division of Molecular Genetics and Center for Biomedical Genetics, The Netherlands Cancer Institute, Amsterdam, The Netherlands
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
30
|
Structural biology of the chromodomain: form and function. Gene 2012; 496:69-78. [PMID: 22285924 DOI: 10.1016/j.gene.2012.01.003] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2011] [Revised: 12/23/2011] [Accepted: 01/05/2012] [Indexed: 11/20/2022]
Abstract
The chromodomain motif is found among certain chromosomal proteins of all eukaryotes. The chromodomain fold - three beta strands packed against a C-terminal alpha helix - mediates protein-protein and/or protein-nucleic acid interactions. In some cases, the affinity of chromodomain binding is regulated by lysine methylation, which appears to target chromodomain proteins and associated complexes to specific sites in chromatin. In this review, our current knowledge of chromodomain structure and function is summarized.
Collapse
|
31
|
Bhandari DR, Seo KW, Jung JW, Kim HS, Yang SR, Kang KS. The regulatory role of c-MYC on HDAC2 and PcG expression in human multipotent stem cells. J Cell Mol Med 2011; 15:1603-14. [PMID: 20716118 PMCID: PMC3823204 DOI: 10.1111/j.1582-4934.2010.01144.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Myelocytomatosis oncogene (c-MYC) is a well-known nuclear oncoprotein having multiple functions in cell proliferation, apoptosis and cellular transformation. Chromosomal modification is also important to the differentiation and growth of stem cells. Histone deacethylase (HDAC) and polycomb group (PcG) family genes are well-known chromosomal modification genes. The aim of this study was to elucidate the role of c-MYC in the expression of chromosomal modification via the HDAC family genes in human mesenchymal stem cells (hMSCs). To achieve this goal, c-MYC expression was modified by gene knockdown and overexpression via lentivirus vector. Using the modified c-MYC expression, our study was focused on cell proliferation, differentiation and cell cycle. Furthermore, the relationship of c-MYC with HDAC2 and PcG genes was also examined. The cell proliferation and differentiation were checked and shown to be dramatically decreased in c-MYC knocked-down human umbilical cord blood-derived MSCs, whereas they were increased in c-MYC overexpressing cells. Similarly, RT-PCR and Western blotting results revealed that HDAC2 expression was decreased in c-MYC knocked-down and increased in c-MYC overexpressing hMSCs. Database indicates presence of c-MYC binding motif in HDAC2 promoter region, which was confirmed by chromatin immunoprecipitation assay. The influence of c-MYC and HDAC2 on PcG expression was confirmed. This might indicate the regulatory role of c-MYC over HDAC2 and PcG genes. c-MYCs’ regulatory role over HDAC2 was also confirmed in human adipose tissue-derived MSCs and bone-marrow derived MSCs. From this finding, it can be concluded that c-MYC plays a vital role in cell proliferation and differentiation via chromosomal modification.
Collapse
Affiliation(s)
- Dilli Ram Bhandari
- Adult Stem Cell Research Center, College of Veterinary Medicine, Seoul National University, Seoul, Republic of Korea
| | | | | | | | | | | |
Collapse
|
32
|
Abstract
The chromatin organization modifier domain (chromodomain) was first identified as a motif associated with chromatin silencing in Drosophila. There is growing evidence that chromodomains are evolutionary conserved across different eukaryotic species to control diverse aspects of epigenetic regulation. Although originally reported as histone H3 methyllysine readers, the chromodomain functions have now expanded to recognition of other histone and non-histone partners as well as interaction with nucleic acids. Chromodomain binding to a diverse group of targets is mediated by a conserved substructure called the chromobox homology region. This motif can be used to predict methyllysine binding and distinguish chromodomains from related Tudor "Royal" family members. In this review, we discuss and classify various chromodomains according to their context, structure and the mechanism of target recognition.
Collapse
Affiliation(s)
- Bartlomiej J Blus
- Diabetes and Obesity Research Center, Sanford-Burnham Medical Research Institute, Orlando, FL, USA
| | | | | |
Collapse
|
33
|
Katsuyama T, Paro R. Epigenetic reprogramming during tissue regeneration. FEBS Lett 2011; 585:1617-24. [PMID: 21569771 DOI: 10.1016/j.febslet.2011.05.010] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2011] [Revised: 05/03/2011] [Accepted: 05/03/2011] [Indexed: 12/31/2022]
Abstract
Epigenetic control of gene regulation is fundamental to the maintenance of cellular identities during all stages of metazoan life. Tissue regeneration involves cellular reprogramming processes, like dedifferentiation, re-differentiation, and trans-differentiation. Hence, in these processes epigenetic maintenance of gene expression programs requires a resetting through mechanisms that we are only beginning to understand. Here we summarize the current status of these studies, in particular regarding the role of epigenetic mechanisms of cellular reprogramming during tissue regeneration.
Collapse
Affiliation(s)
- Tomonori Katsuyama
- Department of Biosystems Science and Engineering, ETH Zurich, Zurich, Switzerland.
| | | |
Collapse
|
34
|
Abstract
Polycomb group (PcG) proteins regulate gene expression in embryonic and adult stem cells, but the mechanisms responsible for PcG gene targeting and regulation remain largely unknown. Recent evidence shows that EZH2, the enzymatic subunit of Polycomb Repressive Complex 2 (PRC2), is a nuclear phosphoprotein linking cell-cycle-intrinsic or extracellular signals to specific epigenetic signatures.
Collapse
Affiliation(s)
- Giuseppina Caretti
- Department of Biomolecular Sciences and Biotechnology, University of Milan, 20133 Milan, Italy
| | - Daniela Palacios
- Dulbecco Telethon Institute (DTI), IRCCS Fondazione Santa Lucia and European Brain Research Institute, 00143 Rome, Italy
| | - Vittorio Sartorelli
- Laboratory of Muscle Stem Cells and Gene Regulation, NIAMS, National Institutes of Health, Bethesda, MD 20892-8022, USA
| | - Pier Lorenzo Puri
- Dulbecco Telethon Institute (DTI), IRCCS Fondazione Santa Lucia and European Brain Research Institute, 00143 Rome, Italy
- Sanford-Burnham Institute for Medical Research, La Jolla, CA 92037, USA
| |
Collapse
|
35
|
Yap KL, Zhou MM. Structure and mechanisms of lysine methylation recognition by the chromodomain in gene transcription. Biochemistry 2011; 50:1966-80. [PMID: 21288002 DOI: 10.1021/bi101885m] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Histone methylation recognition is accomplished by a number of evolutionarily conserved protein domains, including those belonging to the methylated lysine-binding Royal family of structural folds. One well-known member of the Royal family, the chromodomain, is found in the HP1/chromobox and CHD subfamilies of proteins, in addition to a small number of other proteins that are involved in chromatin remodeling and gene transcriptional silencing. Here we discuss the structure and function of the chromodomain within these proteins as methylated histone lysine binders and how the functions of these chromodomains can be modulated by additional post-translational modifications or binding to nucleic acids.
Collapse
Affiliation(s)
- Kyoko L Yap
- Department of Structural and Chemical Biology, Mount Sinai School of Medicine, One Gustave L. Levy Place, Box 1677, New York, New York 10065, United States
| | | |
Collapse
|
36
|
The Arabidopsis CUL4-DDB1 complex interacts with MSI1 and is required to maintain MEDEA parental imprinting. EMBO J 2011; 30:731-43. [PMID: 21240189 DOI: 10.1038/emboj.2010.359] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2010] [Accepted: 12/13/2010] [Indexed: 11/08/2022] Open
Abstract
Protein ubiquitylation regulates a broad variety of biological processes in all eukaryotes. Recent work identified a novel class of cullin-containing ubiquitin ligases (E3s) composed of CUL4, DDB1, and one WD40 protein, believed to act as a substrate receptor. Strikingly, CUL4-based E3 ligases (CRL4s) have important functions at the chromatin level, including responses to DNA damage in metazoans and plants and, in fission yeast, in heterochromatin silencing. Among putative CRL4 receptors we identified MULTICOPY SUPPRESSOR OF IRA1 (MSI1), which belongs to an evolutionary conserved protein family. MSI1-like proteins contribute to different protein complexes, including the epigenetic regulatory Polycomb repressive complex 2 (PRC2). Here, we provide evidence that Arabidopsis MSI1 physically interacts with DDB1A and is part of a multimeric protein complex including CUL4. CUL4 and DDB1 loss-of-function lead to embryo lethality. Interestingly, as in fis class mutants, cul4 mutants exhibit autonomous endosperm initiation and loss of parental imprinting of MEDEA, a target gene of the Arabidopsis PRC2 complex. In addition, after pollination both MEDEA transcript and protein accumulate in a cul4 mutant background. Overall, our work provides the first evidence of a physical and functional link between a CRL4 E3 ligase and a PRC2 complex, thus indicating a novel role of ubiquitylation in the repression of gene expression.
Collapse
|
37
|
Nelissen ECM, van Montfoort APA, Dumoulin JCM, Evers JLH. Epigenetics and the placenta. Hum Reprod Update 2010; 17:397-417. [PMID: 20959349 DOI: 10.1093/humupd/dmq052] [Citation(s) in RCA: 254] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND The placenta is of utmost importance for intrauterine fetal development and growth. Deregulation of placentation can lead to adverse outcomes for both mother and fetus, e.g. gestational trophoblastic disease (GTD), pre-eclampsia and fetal growth retardation. A significant factor in placental development and function is epigenetic regulation. METHODS This review summarizes the current knowledge in the field of epigenetics in relation to placental development and function. Relevant studies were identified by searching PubMed, Medline and reference sections of all relevant studies and reviews. RESULTS Epigenetic regulation of the placenta evolves during preimplantation development and further gestation. Epigenetic marks, like DNA methylation, histone modifications and non-coding RNAs, affect gene expression patterns. These expression patterns, including the important parent-of-origin-dependent gene expression resulting from genomic imprinting, play a pivotal role in proper fetal and placental development. Disturbed placental epigenetics has been demonstrated in cases of intrauterine growth retardation and small for gestational age, and also appears to be involved in the pathogenesis of pre-eclampsia and GTD. Several environmental effects have been investigated so far, e.g. ethanol, oxygen tension as well as the effect of several aspects of assisted reproduction technologies on placental epigenetics. CONCLUSIONS Studies in both animals and humans have made it increasingly clear that proper epigenetic regulation of both imprinted and non-imprinted genes is important in placental development. Its disturbance, which can be caused by various environmental factors, can lead to abnormal placental development and function with possible consequences for maternal morbidity, fetal development and disease susceptibility in later life.
Collapse
Affiliation(s)
- Ewka C M Nelissen
- Department of Obstetrics and Gynaecology, Research Institute Growth & Development (GROW), Center for Reproductive Medicine, Maastricht University Medical Centre, MUMC+, PO Box 5800, 6202 AZ Maastricht, The Netherlands.
| | | | | | | |
Collapse
|
38
|
Van Dessel N, Beke L, Görnemann J, Minnebo N, Beullens M, Tanuma N, Shima H, Van Eynde A, Bollen M. The phosphatase interactor NIPP1 regulates the occupancy of the histone methyltransferase EZH2 at Polycomb targets. Nucleic Acids Res 2010; 38:7500-12. [PMID: 20671031 PMCID: PMC2995064 DOI: 10.1093/nar/gkq643] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Polycomb group (PcG) proteins are key regulators of stem-cell and cancer biology. They mainly act as repressors of differentiation and tumor-suppressor genes. One key silencing step involves the trimethylation of histone H3 on Lys27 (H3K27) by EZH2, a core component of the Polycomb Repressive Complex 2 (PRC2). The mechanism underlying the initial recruitment of mammalian PRC2 complexes is not well understood. Here, we show that NIPP1, a regulator of protein Ser/Thr phosphatase-1 (PP1), forms a complex with PP1 and PRC2 components on chromatin. The knockdown of NIPP1 or PP1 reduced the association of EZH2 with a subset of its target genes, whereas the overexpression of NIPP1 resulted in a retargeting of EZH2 from fully repressed to partially active PcG targets. However, the expression of a PP1-binding mutant of NIPP1 (NIPP1m) did not cause a redistribution of EZH2. Moreover, mapping of the chromatin binding sites with the DamID technique revealed that NIPP1 was associated with multiple PcG target genes, including the Homeobox A cluster, whereas NIPP1m showed a deficient binding at these loci. We propose that NIPP1 associates with a subset of PcG targets in a PP1-dependent manner and thereby contributes to the recruitment of the PRC2 complex.
Collapse
Affiliation(s)
- Nele Van Dessel
- Laboratory of Biosignaling and Therapeutics, Department of Molecular Cell Biology, Faculty of Medicine, KULeuven, B-3000 Leuven, Belgium
| | | | | | | | | | | | | | | | | |
Collapse
|