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Kim SJ, Kiser PK, Asfaha S, DeKoter RP, Dick FA. EZH2 inhibition stimulates repetitive element expression and viral mimicry in resting splenic B cells. EMBO J 2023; 42:e114462. [PMID: 37934086 PMCID: PMC10711652 DOI: 10.15252/embj.2023114462] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2023] [Revised: 10/19/2023] [Accepted: 10/25/2023] [Indexed: 11/08/2023] Open
Abstract
Mammalian cells repress expression of repetitive genomic sequences by forming heterochromatin. However, the consequences of ectopic repeat expression remain unclear. Here we demonstrate that inhibitors of EZH2, the catalytic subunit of the Polycomb repressive complex 2 (PRC2), stimulate repeat misexpression and cell death in resting splenic B cells. B cells are uniquely sensitive to these agents because they exhibit high levels of histone H3 lysine 27 trimethylation (H3K27me3) and correspondingly low DNA methylation at repeat elements. We generated a pattern recognition receptor loss-of-function mouse model, called RIC, with mutations in Rigi (encoding for RIG-I), Ifih1 (MDA5), and Cgas. In both wildtype and RIC mutant B cells, EZH2 inhibition caused loss of H3K27me3 at repetitive elements and upregulated their expression. However, NF-κB-dependent expression of inflammatory chemokines and subsequent cell death was suppressed by the RIC mutations. We further show that inhibition of EZH2 in cancer cells requires the same pattern recognition receptors to activate an interferon response. Together, the results reveal chemokine expression induced by EZH2 inhibitors in B cells as a novel inflammatory response to genomic repeat expression. Given the overlap of genes induced by EZH2 inhibitors and Epstein-Barr virus infection, this response can be described as a form of viral mimicry.
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Affiliation(s)
- Seung J Kim
- London Regional Cancer ProgramChildren's Health Research InstituteLondonONCanada
- London Health Sciences Research InstituteLondonONCanada
- Department of BiochemistryWestern UniversityLondonONCanada
| | - Patti K Kiser
- Department of Pathology and Laboratory MedicineWestern UniversityLondonONCanada
| | - Samuel Asfaha
- London Regional Cancer ProgramChildren's Health Research InstituteLondonONCanada
- London Health Sciences Research InstituteLondonONCanada
- Department of Pathology and Laboratory MedicineWestern UniversityLondonONCanada
- Department of MedicineWestern UniversityLondonONCanada
| | - Rodney P DeKoter
- Department of Microbiology & ImmunologyWestern UniversityLondonONCanada
| | - Frederick A Dick
- London Regional Cancer ProgramChildren's Health Research InstituteLondonONCanada
- London Health Sciences Research InstituteLondonONCanada
- Department of Pathology and Laboratory MedicineWestern UniversityLondonONCanada
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2
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Alves VC, Figueiro-Silva J, Ferrer I, Carro E. Epigenetic silencing of OR and TAS2R genes expression in human orbitofrontal cortex at early stages of sporadic Alzheimer's disease. Cell Mol Life Sci 2023; 80:196. [PMID: 37405535 PMCID: PMC10322771 DOI: 10.1007/s00018-023-04845-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Revised: 06/06/2023] [Accepted: 06/21/2023] [Indexed: 07/06/2023]
Abstract
Modulation of brain olfactory (OR) and taste receptor (TASR) expression was recently reported in neurological diseases. However, there is still limited evidence of these genes' expression in the human brain and the transcriptional regulation mechanisms involved remain elusive. We explored the possible expression and regulation of selected OR and TASR in the human orbitofrontal cortex (OFC) of sporadic Alzheimer's disease (AD) and non-demented control specimens using quantitative real-time RT-PCR and ELISA. Global H3K9me3 amounts were measured on OFC total histone extracts, and H3K9me3 binding at each chemoreceptor locus was examined through native chromatin immunoprecipitation. To investigate the potential interactome of the repressive histone mark H3K9me3 in OFC specimens, native nuclear complex co-immunoprecipitation (Co-IP) was combined with reverse phase-liquid chromatography coupled to mass spectrometry analysis. Interaction between H3K9me3 and MeCP2 was validated by reciprocal Co-IP, and global MeCP2 levels were quantitated. We found that OR and TAS2R genes are expressed and markedly downregulated in OFC at early stages of sporadic AD, preceding the progressive reduction in their protein levels and the appearance of AD-associated neuropathology. The expression pattern did not follow disease progression suggesting transcriptional regulation through epigenetic mechanisms. We discovered an increase of OFC global H3K9me3 levels and a substantial enrichment of this repressive signature at ORs and TAS2Rs proximal promoter at early stages of AD, ultimately lost at advanced stages. We revealed the interaction between H3K9me3 and MeCP2 at early stages and found that MeCP2 protein is increased in sporadic AD. Findings suggest MeCP2 might be implicated in OR and TAS2R transcriptional regulation through interaction with H3K9me3, and as an early event, it may uncover a novel etiopathogenetic mechanism of sporadic AD.
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Affiliation(s)
- Victoria Cunha Alves
- Neurodegenerative Diseases Group, Hospital Universitario 12 de Octubre Research Institute (imas12), Madrid, Spain
- Network Center for Biomedical Research, Neurodegenerative Diseases (CIBERNED), Madrid, Spain
- PhD Program in Neuroscience, Autonoma de Madrid University, Madrid, Spain
| | - Joana Figueiro-Silva
- Neurodegenerative Diseases Group, Hospital Universitario 12 de Octubre Research Institute (imas12), Madrid, Spain
- Institute of Medical Genetics, University of Zurich, Zurich, Switzerland
- Department of Molecular Life Science, University of Zurich, Zurich, Switzerland
| | - Isidre Ferrer
- Network Center for Biomedical Research, Neurodegenerative Diseases (CIBERNED), Madrid, Spain
- Institute of Neuropathology, Bellvitge University Hospital-IDIBELL, Barcelona, Spain
- University of Barcelona, Barcelona, Spain
| | - Eva Carro
- Neurodegenerative Diseases Group, Hospital Universitario 12 de Octubre Research Institute (imas12), Madrid, Spain
- Network Center for Biomedical Research, Neurodegenerative Diseases (CIBERNED), Madrid, Spain
- Present Address: Neurobiology of Alzheimer’s Disease Unit, Functional Unit for Research Into Chronic Diseases, Instituto de Salud Carlos III, Madrid, Spain
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Warsinger-Pepe N, Chang C, Desroberts CR, Akbari OS. Polycomb response elements reduce leaky expression of Cas9 under temperature-inducible Hsp70Bb promoter in Drosophila melanogaster. G3 (BETHESDA, MD.) 2023; 13:jkad024. [PMID: 36705519 PMCID: PMC10085756 DOI: 10.1093/g3journal/jkad024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Revised: 12/15/2022] [Accepted: 01/19/2023] [Indexed: 01/28/2023]
Abstract
Heat-shock-inducible expression of genes through the use of heat-inducible promoters is commonly used in research despite leaky expression of downstream genes of interest without targeted induction (i.e. heat shock). The development of non-leaky inducible expression systems is of broad interest for both basic and applied studies, to precisely control gene expression. Here we characterize the use of Polycomb response elements and the inducible Heat-shock protein 70Bb promoter, previously described as a non-leaky inducible system, to regulate Cas9 endonuclease levels and function in Drosophila melanogaster after varying both heat-shock durations and rearing temperatures. We show that Polycomb response elements can significantly reduce expression of Cas9 under Heat-shock protein 70Bb promoter control using a range of conditions, corroborating previously published results. We further demonstrate that this low transcript level of heat-induced Cas9 is sufficient to induce mutant mosaic phenotypes. Incomplete suppression of an inducible Cas9 system by Polycomb response elements with no heat-shock suggests that further regulatory elements are required to precisely control Cas9 expression and abundance.
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Affiliation(s)
- Natalie Warsinger-Pepe
- School of Biological Sciences, Department of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA 92093, USA
| | - Carly Chang
- School of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA
| | - Connor R Desroberts
- School of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA
| | - Omar S Akbari
- School of Biological Sciences, Department of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA 92093, USA
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Scholl A, De S. Epigenetic Regulation by Polycomb Complexes from Drosophila to Human and Its Relation to Communicable Disease Pathogenesis. Int J Mol Sci 2022; 23:ijms232012285. [PMID: 36293135 PMCID: PMC9603650 DOI: 10.3390/ijms232012285] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2022] [Revised: 10/04/2022] [Accepted: 10/10/2022] [Indexed: 12/05/2022] Open
Abstract
Although all cells in the human body are made of the same DNA, these cells undergo differentiation and behave differently during development, through integration of external and internal stimuli via 'specific mechanisms.' Epigenetics is one such mechanism that comprises DNA/RNA, histone modifications, and non-coding RNAs that regulate transcription without changing the genetic code. The discovery of the first Polycomb mutant phenotype in Drosophila started the study of epigenetics more than 80 years ago. Since then, a considerable number of Polycomb Group (PcG) genes in Drosophila have been discovered to be preserved in mammals, including humans. PcG proteins exert their influence through gene repression by acting in complexes, modifying histones, and compacting the chromatin within the nucleus. In this article, we discuss how our knowledge of the PcG repression mechanism in Drosophila translates to human communicable disease research.
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Oss-Ronen L, Sarusi T, Cohen I. Histone Mono-Ubiquitination in Transcriptional Regulation and Its Mark on Life: Emerging Roles in Tissue Development and Disease. Cells 2022; 11:cells11152404. [PMID: 35954248 PMCID: PMC9368181 DOI: 10.3390/cells11152404] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 07/26/2022] [Accepted: 08/02/2022] [Indexed: 02/06/2023] Open
Abstract
Epigenetic regulation plays an essential role in driving precise transcriptional programs during development and homeostasis. Among epigenetic mechanisms, histone mono-ubiquitination has emerged as an important post-transcriptional modification. Two major histone mono-ubiquitination events are the mono-ubiquitination of histone H2A at lysine 119 (H2AK119ub), placed by Polycomb repressive complex 1 (PRC1), and histone H2B lysine 120 mono-ubiquitination (H2BK120ub), placed by the heteromeric RNF20/RNF40 complex. Both of these events play fundamental roles in shaping the chromatin epigenetic landscape and cellular identity. In this review we summarize the current understandings of molecular concepts behind histone mono-ubiquitination, focusing on their recently identified roles in tissue development and pathologies.
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Affiliation(s)
| | | | - Idan Cohen
- Correspondence: ; Tel.: +972-8-6477593; Fax: +972-8-6477626
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Forgione I, Muto A, Woloszynska M, Chiappetta AA, Ferrari M, Van Lijsebettens M, Bitonti MB, Bruno L. Epigenetic mechanisms affect the curled leaf phenotype in the hypomethylated ddc mutant of Arabidopsis thaliana. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2022; 319:111254. [PMID: 35487663 DOI: 10.1016/j.plantsci.2022.111254] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Revised: 02/02/2022] [Accepted: 03/12/2022] [Indexed: 06/14/2023]
Abstract
The ddc mutant of Arabidopsis thaliana is characterized by pleiotropic phenotypic alterations including a curl-shaped leaf, previously explained by disturbed auxin metabolism and transport. The present study was aimed at further explore the molecular bases underlying the abnormal phenotype of the ddc leaf. We demonstrated that genes specifically related to leaf fate commitment and morphogenesis were misexpressed on developing ddc leaves, such as upregulation of CURLY LEAF (CLF) and downregulation of ASYMMETRIC LEAVES2 (AS2), KNOTTED-like gene from A. thaliana (KNAT6), TEOSINTE-LIKE1 CYCLOIDEA and PROLIFERATING CELL FACTOR 2 (TCP2) and others. The CLF gene, encoding a component of Polycomb repressive complex 2 (PRC2) which adds trimethylation marks at Lys27 of histone H3, was overexpressed in the ddc mutant and concomitantly was correlated with DNA methylation-dependent repression of its negative regulator UCL1. KNAT6, encoding a class 1 KNOX homeotic gene, had increased H3K27me3 trimethylation levels, suggesting it is a target gene of the CLF containing PRC2 complex in the ddc mutant. We postulate that different epigenetic mechanisms modulate expression of genes related to auxin pathways as well as gene targets of Polycomb repressive action, during leaf morphogenesis.
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Affiliation(s)
- Ivano Forgione
- Department of Biology, Ecology and Earth Science, University of Calabria, Ponte P. Bucci, Arcavacata di Rende, 87036 Cosenza, Italy; Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium; Center Plant Systems Biology, VIB, 9052 Ghent, Belgium.
| | - Antonella Muto
- Department of Biology, Ecology and Earth Science, University of Calabria, Ponte P. Bucci, Arcavacata di Rende, 87036 Cosenza, Italy.
| | - Magdalena Woloszynska
- Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium; Center Plant Systems Biology, VIB, 9052 Ghent, Belgium; Department of Genetics, Faculty of Biology and Animal Sciences, Wroclaw University of Environmental and Life Sciences, ul. Kozuchowska 7, 51-631 Wroclaw, Poland.
| | - Adriana Ada Chiappetta
- Department of Biology, Ecology and Earth Science, University of Calabria, Ponte P. Bucci, Arcavacata di Rende, 87036 Cosenza, Italy.
| | - Michele Ferrari
- Department of Biology, Ecology and Earth Science, University of Calabria, Ponte P. Bucci, Arcavacata di Rende, 87036 Cosenza, Italy.
| | - Mieke Van Lijsebettens
- Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium; Center Plant Systems Biology, VIB, 9052 Ghent, Belgium.
| | - Maria Beatrice Bitonti
- Department of Biology, Ecology and Earth Science, University of Calabria, Ponte P. Bucci, Arcavacata di Rende, 87036 Cosenza, Italy.
| | - Leonardo Bruno
- Department of Biology, Ecology and Earth Science, University of Calabria, Ponte P. Bucci, Arcavacata di Rende, 87036 Cosenza, Italy.
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Zhou H, Stein CB, Shafiq TA, Shipkovenska G, Kalocsay M, Paulo JA, Zhang J, Luo Z, Gygi SP, Adelman K, Moazed D. Rixosomal RNA degradation contributes to silencing of Polycomb target genes. Nature 2022; 604:167-174. [PMID: 35355014 PMCID: PMC8986528 DOI: 10.1038/s41586-022-04598-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Accepted: 02/28/2022] [Indexed: 01/01/2023]
Abstract
Polycomb repressive complexes 1 and 2 (PRC1 and PRC2) are histone-modifying and -binding complexes that mediate the formation of facultative heterochromatin and are required for silencing of developmental genes and maintenance of cell fate1–3. Multiple pathways of RNA decay work together to establish and maintain heterochromatin in fission yeast, including a recently identified role for a conserved RNA-degradation complex known as the rixosome or RIX1 complex4–6. Whether RNA degradation also has a role in the stability of mammalian heterochromatin remains unknown. Here we show that the rixosome contributes to silencing of many Polycomb targets in human cells. The rixosome associates with human PRC complexes and is enriched at promoters of Polycomb target genes. Depletion of either the rixosome or Polycomb results in accumulation of paused and elongating RNA polymerase at Polycomb target genes. We identify point mutations in the RING1B subunit of PRC1 that disrupt the interaction between PRC1 and the rixosome and result in diminished silencing, suggesting that direct recruitment of the rixosome to chromatin is required for silencing. Finally, we show that the RNA endonuclease and kinase activities of the rixosome and the downstream XRN2 exoribonuclease, which degrades RNAs with 5′ monophosphate groups generated by the rixosome, are required for silencing. Our findings suggest that rixosomal degradation of nascent RNA is conserved from fission yeast to human, with a primary role in RNA degradation at facultative heterochromatin in human cells. The rixosome associates with Polycomb repressive complexes and chromatin and has a role in silencing of Polycomb target gene expression in human cells via degradation of nascent RNA transcripts.
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Affiliation(s)
- Haining Zhou
- Howard Hughes Medical Institute, Department of Cell Biology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - Chad B Stein
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - Tiasha A Shafiq
- Howard Hughes Medical Institute, Department of Cell Biology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - Gergana Shipkovenska
- Howard Hughes Medical Institute, Department of Cell Biology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - Marian Kalocsay
- Department of Cell Biology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - Joao A Paulo
- Department of Cell Biology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - Jiuchun Zhang
- Initiative for Genome Editing and Neurodegeneration, Department of Cell Biology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - Zhenhua Luo
- Precision Medicine Institute, the First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Steven P Gygi
- Department of Cell Biology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - Karen Adelman
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - Danesh Moazed
- Howard Hughes Medical Institute, Department of Cell Biology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA.
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Parreno V, Martinez AM, Cavalli G. Mechanisms of Polycomb group protein function in cancer. Cell Res 2022; 32:231-253. [PMID: 35046519 PMCID: PMC8888700 DOI: 10.1038/s41422-021-00606-6] [Citation(s) in RCA: 42] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Accepted: 12/10/2021] [Indexed: 02/01/2023] Open
Abstract
AbstractCancer arises from a multitude of disorders resulting in loss of differentiation and a stem cell-like phenotype characterized by uncontrolled growth. Polycomb Group (PcG) proteins are members of multiprotein complexes that are highly conserved throughout evolution. Historically, they have been described as essential for maintaining epigenetic cellular memory by locking homeotic genes in a transcriptionally repressed state. What was initially thought to be a function restricted to a few target genes, subsequently turned out to be of much broader relevance, since the main role of PcG complexes is to ensure a dynamically choregraphed spatio-temporal regulation of their numerous target genes during development. Their ability to modify chromatin landscapes and refine the expression of master genes controlling major switches in cellular decisions under physiological conditions is often misregulated in tumors. Surprisingly, their functional implication in the initiation and progression of cancer may be either dependent on Polycomb complexes, or specific for a subunit that acts independently of other PcG members. In this review, we describe how misregulated Polycomb proteins play a pleiotropic role in cancer by altering a broad spectrum of biological processes such as the proliferation-differentiation balance, metabolism and the immune response, all of which are crucial in tumor progression. We also illustrate how interfering with PcG functions can provide a powerful strategy to counter tumor progression.
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Blackledge NP, Klose RJ. The molecular principles of gene regulation by Polycomb repressive complexes. Nat Rev Mol Cell Biol 2021; 22:815-833. [PMID: 34400841 PMCID: PMC7612013 DOI: 10.1038/s41580-021-00398-y] [Citation(s) in RCA: 170] [Impact Index Per Article: 56.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/01/2021] [Indexed: 12/12/2022]
Abstract
Precise control of gene expression is fundamental to cell function and development. Although ultimately gene expression relies on DNA-binding transcription factors to guide the activity of the transcription machinery to genes, it has also become clear that chromatin and histone post-translational modification have fundamental roles in gene regulation. Polycomb repressive complexes represent a paradigm of chromatin-based gene regulation in animals. The Polycomb repressive system comprises two central protein complexes, Polycomb repressive complex 1 (PRC1) and PRC2, which are essential for normal gene regulation and development. Our early understanding of Polycomb function relied on studies in simple model organisms, but more recently it has become apparent that this system has expanded and diverged in mammals. Detailed studies are now uncovering the molecular mechanisms that enable mammalian PRC1 and PRC2 to identify their target sites in the genome, communicate through feedback mechanisms to create Polycomb chromatin domains and control transcription to regulate gene expression. In this Review, we discuss and contextualize the emerging principles that define how this fascinating chromatin-based system regulates gene expression in mammals.
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Affiliation(s)
| | - Robert J Klose
- Department of Biochemistry, University of Oxford, Oxford, UK.
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10
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Shaheen N, Akhtar J, Umer Z, Khan MHF, Bakhtiari MH, Saleem M, Faisal A, Tariq M. Polycomb Requires Chaperonin Containing TCP-1 Subunit 7 for Maintaining Gene Silencing in Drosophila. Front Cell Dev Biol 2021; 9:727972. [PMID: 34660585 PMCID: PMC8517254 DOI: 10.3389/fcell.2021.727972] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2021] [Accepted: 08/30/2021] [Indexed: 11/13/2022] Open
Abstract
In metazoans, heritable states of cell type-specific gene expression patterns linked with specialization of various cell types constitute transcriptional cellular memory. Evolutionarily conserved Polycomb group (PcG) and trithorax group (trxG) proteins contribute to the transcriptional cellular memory by maintaining heritable patterns of repressed and active expression states, respectively. Although chromatin structure and modifications appear to play a fundamental role in maintenance of repression by PcG, the precise targeting mechanism and the specificity factors that bind PcG complexes to defined regions in chromosomes remain elusive. Here, we report a serendipitous discovery that uncovers an interplay between Polycomb (Pc) and chaperonin containing T-complex protein 1 (TCP-1) subunit 7 (CCT7) of TCP-1 ring complex (TRiC) chaperonin in Drosophila. CCT7 interacts with Pc at chromatin to maintain repressed states of homeotic and non-homeotic targets of PcG, which supports a strong genetic interaction observed between Pc and CCT7 mutants. Depletion of CCT7 results in dissociation of Pc from chromatin and redistribution of an abundant amount of Pc in cytoplasm. We propose that CCT7 is an important modulator of Pc, which helps Pc recruitment at chromatin, and compromising CCT7 can directly influence an evolutionary conserved epigenetic network that supervises the appropriate cellular identities during development and homeostasis of an organism.
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Affiliation(s)
- Najma Shaheen
- Epigenetics and Gene Regulation Laboratory, Department of Biology, Syed Babar Ali School of Science and Engineering, Lahore University of Management Sciences, Lahore, Pakistan
| | - Jawad Akhtar
- Epigenetics and Gene Regulation Laboratory, Department of Biology, Syed Babar Ali School of Science and Engineering, Lahore University of Management Sciences, Lahore, Pakistan
| | - Zain Umer
- Epigenetics and Gene Regulation Laboratory, Department of Biology, Syed Babar Ali School of Science and Engineering, Lahore University of Management Sciences, Lahore, Pakistan
| | - Muhammad Haider Farooq Khan
- Epigenetics and Gene Regulation Laboratory, Department of Biology, Syed Babar Ali School of Science and Engineering, Lahore University of Management Sciences, Lahore, Pakistan
| | - Mahnoor Hussain Bakhtiari
- Epigenetics and Gene Regulation Laboratory, Department of Biology, Syed Babar Ali School of Science and Engineering, Lahore University of Management Sciences, Lahore, Pakistan
| | - Murtaza Saleem
- Department of Physics, Syed Babar Ali School of Science and Engineering, Lahore University of Management Sciences, Lahore, Pakistan
| | - Amir Faisal
- Cancer Therapeutics Laboratory, Department of Biology, Syed Babar Ali School of Science and Engineering, Lahore University of Management Sciences, Lahore, Pakistan
| | - Muhammad Tariq
- Epigenetics and Gene Regulation Laboratory, Department of Biology, Syed Babar Ali School of Science and Engineering, Lahore University of Management Sciences, Lahore, Pakistan
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11
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Dobrinić P, Szczurek AT, Klose RJ. PRC1 drives Polycomb-mediated gene repression by controlling transcription initiation and burst frequency. Nat Struct Mol Biol 2021; 28:811-824. [PMID: 34608337 PMCID: PMC7612713 DOI: 10.1038/s41594-021-00661-y] [Citation(s) in RCA: 48] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Accepted: 08/10/2021] [Indexed: 12/15/2022]
Abstract
The Polycomb repressive system plays a fundamental role in controlling gene expression during mammalian development. To achieve this, Polycomb repressive complexes 1 and 2 (PRC1 and PRC2) bind target genes and use histone modification-dependent feedback mechanisms to form Polycomb chromatin domains and repress transcription. The inter-relatedness of PRC1 and PRC2 activity at these sites has made it difficult to discover the specific components of Polycomb chromatin domains that drive gene repression and to understand mechanistically how this is achieved. Here, by exploiting rapid degron-based approaches and time-resolved genomics, we kinetically dissect Polycomb-mediated repression and discover that PRC1 functions independently of PRC2 to counteract RNA polymerase II binding and transcription initiation. Using single-cell gene expression analysis, we reveal that PRC1 acts uniformly within the cell population and that repression is achieved by controlling transcriptional burst frequency. These important new discoveries provide a mechanistic and conceptual framework for Polycomb-dependent transcriptional control.
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Affiliation(s)
- Paula Dobrinić
- Department of Biochemistry, University of Oxford, Oxford, UK
| | | | - Robert J Klose
- Department of Biochemistry, University of Oxford, Oxford, UK.
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12
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Flora P, Dalal G, Cohen I, Ezhkova E. Polycomb Repressive Complex(es) and Their Role in Adult Stem Cells. Genes (Basel) 2021; 12:1485. [PMID: 34680880 PMCID: PMC8535826 DOI: 10.3390/genes12101485] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Revised: 09/13/2021] [Accepted: 09/22/2021] [Indexed: 12/31/2022] Open
Abstract
Populations of resident stem cells (SCs) are responsible for maintaining, repairing, and regenerating adult tissues. In addition to having the capacity to generate all the differentiated cell types of the tissue, adult SCs undergo long periods of quiescence within the niche to maintain themselves. The process of SC renewal and differentiation is tightly regulated for proper tissue regeneration throughout an organisms' lifetime. Epigenetic regulators, such as the polycomb group (PcG) of proteins have been implicated in modulating gene expression in adult SCs to maintain homeostatic and regenerative balances in adult tissues. In this review, we summarize the recent findings that elucidate the composition and function of the polycomb repressive complex machinery and highlight their role in diverse adult stem cell compartments.
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Affiliation(s)
- Pooja Flora
- Department of Cell, Developmental, and Regenerative Biology, Black Family Stem Cell Institute, Icahn School of Medicine at Mount Sinai, 1 Gustave L. Levy Place, New York, NY 10029, USA;
| | - Gil Dalal
- The Shraga Segal Department of Microbiology, Immunology and Genetics, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheva 84105, Israel;
| | - Idan Cohen
- The Shraga Segal Department of Microbiology, Immunology and Genetics, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheva 84105, Israel;
| | - Elena Ezhkova
- Department of Cell, Developmental, and Regenerative Biology, Black Family Stem Cell Institute, Icahn School of Medicine at Mount Sinai, 1 Gustave L. Levy Place, New York, NY 10029, USA;
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13
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Fursova NA, Turberfield AH, Blackledge NP, Findlater EL, Lastuvkova A, Huseyin MK, Dobrinić P, Klose RJ. BAP1 constrains pervasive H2AK119ub1 to control the transcriptional potential of the genome. Genes Dev 2021; 35:749-770. [PMID: 33888563 PMCID: PMC8091973 DOI: 10.1101/gad.347005.120] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Accepted: 03/02/2021] [Indexed: 12/21/2022]
Abstract
Histone-modifying systems play fundamental roles in gene regulation and the development of multicellular organisms. Histone modifications that are enriched at gene regulatory elements have been heavily studied, but the function of modifications found more broadly throughout the genome remains poorly understood. This is exemplified by histone H2A monoubiquitylation (H2AK119ub1), which is enriched at Polycomb-repressed gene promoters but also covers the genome at lower levels. Here, using inducible genetic perturbations and quantitative genomics, we found that the BAP1 deubiquitylase plays an essential role in constraining H2AK119ub1 throughout the genome. Removal of BAP1 leads to pervasive genome-wide accumulation of H2AK119ub1, which causes widespread reductions in gene expression. We show that elevated H2AK119ub1 preferentially counteracts Ser5 phosphorylation on the C-terminal domain of RNA polymerase II at gene regulatory elements and causes reductions in transcription and transcription-associated histone modifications. Furthermore, failure to constrain pervasive H2AK119ub1 compromises Polycomb complex occupancy at a subset of Polycomb target genes, which leads to their derepression, providing a potential molecular rationale for why the BAP1 ortholog in Drosophila has been characterized as a Polycomb group gene. Together, these observations reveal that the transcriptional potential of the genome can be modulated by regulating the levels of a pervasive histone modification.
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Affiliation(s)
- Nadezda A Fursova
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, United Kingdom
| | - Anne H Turberfield
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, United Kingdom
| | - Neil P Blackledge
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, United Kingdom
| | - Emma L Findlater
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, United Kingdom
| | - Anna Lastuvkova
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, United Kingdom
| | - Miles K Huseyin
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, United Kingdom
| | - Paula Dobrinić
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, United Kingdom
| | - Robert J Klose
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, United Kingdom
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14
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Heterochromatin and Polycomb as regulators of haematopoiesis. Biochem Soc Trans 2021; 49:805-814. [PMID: 33929498 PMCID: PMC8106494 DOI: 10.1042/bst20200737] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2021] [Revised: 04/12/2021] [Accepted: 04/14/2021] [Indexed: 12/23/2022]
Abstract
Haematopoiesis is the process by which multipotent haematopoietic stem cells are transformed into each and every type of terminally differentiated blood cell. Epigenetic silencing is critical for this process by regulating the transcription of cell-cycle genes critical for self-renewal and differentiation, as well as restricting alternative fate genes to allow lineage commitment and appropriate differentiation. There are two distinct forms of transcriptionally repressed chromatin: H3K9me3-marked heterochromatin and H3K27me3/H2AK119ub1-marked Polycomb (often referred to as facultative heterochromatin). This review will discuss the role of these distinct epigenetic silencing mechanisms in regulating normal haematopoiesis, how these contribute to age-related haematopoietic dysfunction, and the rationale for therapeutic targeting of these pathways in the treatment of haematological malignancies.
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15
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The Role of Polycomb Group Protein BMI1 in DNA Repair and Genomic Stability. Int J Mol Sci 2021; 22:ijms22062976. [PMID: 33804165 PMCID: PMC7998361 DOI: 10.3390/ijms22062976] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Accepted: 03/09/2021] [Indexed: 12/31/2022] Open
Abstract
The polycomb group (PcG) proteins are a class of transcriptional repressors that mediate gene silencing through histone post-translational modifications. They are involved in the maintenance of stem cell self-renewal and proliferation, processes that are often dysregulated in cancer. Apart from their canonical functions in epigenetic gene silencing, several studies have uncovered a function for PcG proteins in DNA damage signaling and repair. In particular, members of the poly-comb group complexes (PRC) 1 and 2 have been shown to recruit to sites of DNA damage and mediate DNA double-strand break repair. Here, we review current understanding of the PRCs and their roles in cancer development. We then focus on the PRC1 member BMI1, discussing the current state of knowledge of its role in DNA repair and genome integrity, and outline how it can be targeted pharmacologically.
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16
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Khan MHF, Akhtar J, Umer Z, Shaheen N, Shaukat A, Munir MS, Mithani A, Anwar S, Tariq M. Kinome-Wide RNAi Screen Uncovers Role of Ballchen in Maintenance of Gene Activation by Trithorax Group in Drosophila. Front Cell Dev Biol 2021; 9:637873. [PMID: 33748127 PMCID: PMC7973098 DOI: 10.3389/fcell.2021.637873] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Accepted: 02/15/2021] [Indexed: 12/19/2022] Open
Abstract
Polycomb group (PcG) and trithorax group (trxG) proteins are evolutionary conserved factors that contribute to cell fate determination and maintenance of cellular identities during development of multicellular organisms. The PcG maintains heritable patterns of gene silencing while trxG acts as anti-silencing factors by conserving activation of cell type specific genes. Genetic and molecular analysis has revealed extensive details about how different PcG and trxG complexes antagonize each other to maintain cell fates, however, the cellular signaling components that contribute to the preservation of gene expression by PcG/trxG remain elusive. Here, we report an ex vivo kinome-wide RNAi screen in Drosophila aimed at identifying cell signaling genes that facilitate trxG in counteracting PcG mediated repression. From the list of trxG candidates, Ballchen (BALL), a histone kinase known to phosphorylate histone H2A at threonine 119 (H2AT119p), was characterized as a trxG regulator. The ball mutant exhibits strong genetic interactions with Polycomb (Pc) and trithorax (trx) mutants and loss of BALL affects expression of trxG target genes. BALL co-localizes with Trithorax on chromatin and depletion of BALL results in increased H2AK118 ubiquitination, a histone mark central to PcG mediated gene silencing. Moreover, BALL was found to substantially associate with known TRX binding sites across the genome. Genome wide distribution of BALL also overlaps with H3K4me3 and H3K27ac at actively transcribed genes. We propose that BALL mediated signaling positively contributes to the maintenance of gene activation by trxG in counteracting the repressive effect of PcG.
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Affiliation(s)
- Muhammad Haider Farooq Khan
- Department of Biology, Syed Babar Ali School of Science and Engineering, Lahore University of Management Sciences, Lahore, Pakistan
| | - Jawad Akhtar
- Department of Biology, Syed Babar Ali School of Science and Engineering, Lahore University of Management Sciences, Lahore, Pakistan
| | - Zain Umer
- Department of Biology, Syed Babar Ali School of Science and Engineering, Lahore University of Management Sciences, Lahore, Pakistan
| | - Najma Shaheen
- Department of Biology, Syed Babar Ali School of Science and Engineering, Lahore University of Management Sciences, Lahore, Pakistan
| | - Ammad Shaukat
- Department of Biology, Syed Babar Ali School of Science and Engineering, Lahore University of Management Sciences, Lahore, Pakistan
| | - Muhammad Shahbaz Munir
- Department of Biology, Syed Babar Ali School of Science and Engineering, Lahore University of Management Sciences, Lahore, Pakistan
| | - Aziz Mithani
- Department of Biology, Syed Babar Ali School of Science and Engineering, Lahore University of Management Sciences, Lahore, Pakistan
| | - Saima Anwar
- Department of Biology, Syed Babar Ali School of Science and Engineering, Lahore University of Management Sciences, Lahore, Pakistan
| | - Muhammad Tariq
- Department of Biology, Syed Babar Ali School of Science and Engineering, Lahore University of Management Sciences, Lahore, Pakistan
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17
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Bairzin JCD, Emmons-Bell M, Hariharan IK. The Hippo pathway coactivator Yorkie can reprogram cell fates and create compartment-boundary-like interactions at clone margins. SCIENCE ADVANCES 2020; 6:6/50/eabe8159. [PMID: 33298454 PMCID: PMC7725458 DOI: 10.1126/sciadv.abe8159] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Accepted: 10/22/2020] [Indexed: 06/12/2023]
Abstract
During development, tissue-specific patterns of gene expression are established by transcription factors and then stably maintained via epigenetic mechanisms. Cancer cells often express genes that are inappropriate for that tissue or developmental stage. Here, we show that high activity levels of Yki, the Hippo pathway coactivator that causes overgrowth in Drosophila imaginal discs, can also disrupt cell fates by altering expression of selector genes like engrailed (en) and Ultrabithorax (Ubx). Posterior clones expressing activated Yki can down-regulate en and express an anterior selector gene, cubitus interruptus (ci). The microRNA bantam and the chromatin regulator Taranis both function downstream of Yki in promoting ci expression. The boundary between Yki-expressing posterior clones and surrounding wild-type cells acquires properties reminiscent of the anteroposterior compartment boundary; Hedgehog signaling pathway activation results in production of Dpp. Thus, at least in principle, heterotypic interactions between Yki-expressing cells and their neighbors could activate boundary-specific signaling mechanisms.
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Affiliation(s)
- Joanna C D Bairzin
- Department of Molecular and Cell Biology, 515 Weill Hall, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Maya Emmons-Bell
- Department of Molecular and Cell Biology, 515 Weill Hall, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Iswar K Hariharan
- Department of Molecular and Cell Biology, 515 Weill Hall, University of California, Berkeley, Berkeley, CA 94720, USA.
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18
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Dumasia NP, Pethe PS. Pancreas development and the Polycomb group protein complexes. Mech Dev 2020; 164:103647. [PMID: 32991980 DOI: 10.1016/j.mod.2020.103647] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 09/02/2020] [Accepted: 09/17/2020] [Indexed: 02/07/2023]
Abstract
The dual nature of pancreatic tissue permits both endocrine and exocrine functions. Enzymatic secretions by the exocrine pancreas help digestive processes while the pancreatic hormones regulate glucose homeostasis and energy metabolism. Pancreas organogenesis is defined by a conserved array of signaling pathways that act on common gut progenitors to bring about the generation of diverse cell types. Multiple cellular processes characterize development of the mature organ. These processes are mediated by signaling pathways that regulate lineage-specific transcription factors and chromatin modifications guiding long-term gene expression programs. The chromatin landscape is altered chiefly by DNA or histone modifications, chromatin remodelers, and non-coding RNAs. Amongst histone modifiers, several studies have identified Polycomb group (PcG) proteins as crucial determinants mediating transcriptional repression of genes involved in developmental processes. Although PcG-mediated chromatin modifications define cellular transitions and influence cell identity of multipotent progenitors, much remains to be understood regarding coordination between extracellular signals and their impact on Polycomb functions during the pancreas lineage progression. In this review, we discuss interactions between sequence-specific DNA binding proteins and chromatin regulators underlying pancreas development and insulin producing β-cells, with particular focus on Polycomb group proteins. Understanding such basic molecular mechanisms would improve current strategies for stem cell-based differentiation while also help elucidate the pathogenesis of several pancreas-related maladies, including diabetes and pancreatic cancer.
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Affiliation(s)
- Niloufer P Dumasia
- Department of Biological Sciences, Sunandan Divatia School of Science, SVKM's NMIMS (deemed to-be) University, Mumbai 400 056, India
| | - Prasad S Pethe
- Symbiosis Centre for Stem Cell Research (SCSCR), Symbiosis International University, Lavale, Pune 412 115, India.
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19
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Walther M, Schrahn S, Krauss V, Lein S, Kessler J, Jenuwein T, Reuter G. Heterochromatin formation in Drosophila requires genome-wide histone deacetylation in cleavage chromatin before mid-blastula transition in early embryogenesis. Chromosoma 2020; 129:83-98. [PMID: 31950239 PMCID: PMC7021753 DOI: 10.1007/s00412-020-00732-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Revised: 12/13/2019] [Accepted: 01/02/2020] [Indexed: 02/05/2023]
Abstract
Su(var) mutations define epigenetic factors controlling heterochromatin formation and gene silencing in Drosophila. Here, we identify SU(VAR)2-1 as a novel chromatin regulator that directs global histone deacetylation during the transition of cleavage chromatin into somatic blastoderm chromatin in early embryogenesis. SU(VAR)2-1 is heterochromatin-associated in blastoderm nuclei but not in later stages of development. In larval polytene chromosomes, SU(VAR)2-1 is a band-specific protein. SU(VAR)2-1 directs global histone deacetylation by recruiting the histone deacetylase RPD3. In Su(var)2-1 mutants H3K9, H3K27, H4K8 and H4K16 acetylation shows elevated levels genome-wide and heterochromatin displays aberrant histone hyper-acetylation. Whereas H3K9me2- and HP1a-binding appears unaltered, the heterochromatin-specific H3K9me2S10ph composite mark is impaired in heterochromatic chromocenters of larval salivary polytene chromosomes. SU(VAR)2-1 contains an NRF1/EWG domain and a C2HC zinc-finger motif. Our study identifies SU(VAR)2-1 as a dosage-dependent, heterochromatin-initiating SU(VAR) factor, where the SU(VAR)2-1-mediated control of genome-wide histone deacetylation after cleavage and before mid-blastula transition (pre-MBT) is required to enable heterochromatin formation.
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Affiliation(s)
- Matthias Walther
- Developmental Genetics, Institute of Biology, Martin Luther University Halle, Weinbergweg 10, 06120, Halle/S., Germany
- Max Planck Institute of Immunobiology and Epigenetics, Stübeweg 51, 79108, Freiburg, Germany
| | - Sandy Schrahn
- Developmental Genetics, Institute of Biology, Martin Luther University Halle, Weinbergweg 10, 06120, Halle/S., Germany
| | - Veiko Krauss
- Cluster of Excellence in Plant Science (CEPLAS), University of Cologne, Biocenter, 50674, Cologne, Germany
| | - Sandro Lein
- Developmental Genetics, Institute of Biology, Martin Luther University Halle, Weinbergweg 10, 06120, Halle/S., Germany
| | - Jeannette Kessler
- Developmental Genetics, Institute of Biology, Martin Luther University Halle, Weinbergweg 10, 06120, Halle/S., Germany
| | - Thomas Jenuwein
- Max Planck Institute of Immunobiology and Epigenetics, Stübeweg 51, 79108, Freiburg, Germany
| | - Gunter Reuter
- Developmental Genetics, Institute of Biology, Martin Luther University Halle, Weinbergweg 10, 06120, Halle/S., Germany.
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20
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Flamier A, Abdouh M, Hamam R, Barabino A, Patel N, Gao A, Hanna R, Bernier G. Off-target effect of the BMI1 inhibitor PTC596 drives epithelial-mesenchymal transition in glioblastoma multiforme. NPJ Precis Oncol 2020; 4:1. [PMID: 31934644 PMCID: PMC6944693 DOI: 10.1038/s41698-019-0106-1] [Citation(s) in RCA: 54] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2019] [Accepted: 10/25/2019] [Indexed: 01/09/2023] Open
Abstract
Glioblastoma multiforme (GBM) is an incurable primary brain tumor containing a sub-population of cancer stem cells (CSCs). Polycomb Repressive Complex (PRC) proteins BMI1 and EZH2 are enriched in CSCs, promoting clonogenic growth and resistance to genotoxic therapies. We report here that when used at appropriate concentrations, pharmaceutical inhibitors of BMI1 could efficiently prevent GBM colony growth and CSC self-renewal in vitro and significantly extend lifespan in terminally ill tumor-bearing mice. Notably, molecular analyses revealed that the commonly used PTC596 molecule targeted both BMI1 and EZH2, possibly providing beneficial therapeutic effects in some contexts. On the other hand, treatment with PTC596 resulted in instant reactivation of EZH2 target genes and induction of a molecular program of epithelial–mesenchymal transition (EMT), possibly explaining the modified phenotype of some PTC596-treated tumors. Treatment with a related but more specific BMI1 inhibitor resulted in tumor regression and maintenance of cell identity. We conclude that inhibition of BMI1 alone is efficient at inducing GBM regression, and that dual inhibition of BMI1 and EZH2 using PTC596 may be also beneficial but only in specific contexts.
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Affiliation(s)
- Anthony Flamier
- 1Stem Cell and Developmental Biology Laboratory, Hôpital Maisonneuve-Rosemont, 5415 Boul. l'Assomption, Montréal, H1T 2M4 Canada.,3Present Address: Whitehead Institute of Biomedical Research, 455 Main Street, Cambridge, 02142 MA USA
| | - Mohamed Abdouh
- 1Stem Cell and Developmental Biology Laboratory, Hôpital Maisonneuve-Rosemont, 5415 Boul. l'Assomption, Montréal, H1T 2M4 Canada
| | - Rimi Hamam
- 1Stem Cell and Developmental Biology Laboratory, Hôpital Maisonneuve-Rosemont, 5415 Boul. l'Assomption, Montréal, H1T 2M4 Canada
| | - Andrea Barabino
- 1Stem Cell and Developmental Biology Laboratory, Hôpital Maisonneuve-Rosemont, 5415 Boul. l'Assomption, Montréal, H1T 2M4 Canada
| | - Niraj Patel
- 1Stem Cell and Developmental Biology Laboratory, Hôpital Maisonneuve-Rosemont, 5415 Boul. l'Assomption, Montréal, H1T 2M4 Canada
| | - Andy Gao
- 1Stem Cell and Developmental Biology Laboratory, Hôpital Maisonneuve-Rosemont, 5415 Boul. l'Assomption, Montréal, H1T 2M4 Canada
| | - Roy Hanna
- 1Stem Cell and Developmental Biology Laboratory, Hôpital Maisonneuve-Rosemont, 5415 Boul. l'Assomption, Montréal, H1T 2M4 Canada
| | - Gilbert Bernier
- 1Stem Cell and Developmental Biology Laboratory, Hôpital Maisonneuve-Rosemont, 5415 Boul. l'Assomption, Montréal, H1T 2M4 Canada.,2Department of Neurosciences, University of Montreal, Montreal, Canada
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21
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Polycomb Assemblies Multitask to Regulate Transcription. EPIGENOMES 2019; 3:epigenomes3020012. [PMID: 34968234 PMCID: PMC8594731 DOI: 10.3390/epigenomes3020012] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Revised: 06/14/2019] [Accepted: 06/16/2019] [Indexed: 02/06/2023] Open
Abstract
The Polycomb system is made of an evolutionary ancient group of proteins, present throughout plants and animals. Known initially from developmental studies with the fly Drosophila melanogaster, they were associated with stable sustainment of gene repression and maintenance of cell identity. Acting as multiprotein assemblies with an ability to modify chromatin, through chemical additions to histones and organization of topological domains, they have been involved subsequently in control of developmental transitions and in cell homeostasis. Recent work has unveiled an association of Polycomb components with transcriptionally active loci and the promotion of gene expression, in clear contrast with conventional recognition as repressors. Focusing on mammalian models, I review here advances concerning roles in transcriptional control. Among new findings highlighted is the regulation of their catalytic properties, recruiting to targets, and activities in chromatin organization and compartmentalization. The need for a more integrated approach to the study of the Polycomb system, given its fundamental complexity and its adaptation to cell context, is discussed.
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22
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Nicetto D, Zaret KS. Role of H3K9me3 heterochromatin in cell identity establishment and maintenance. Curr Opin Genet Dev 2019; 55:1-10. [PMID: 31103921 DOI: 10.1016/j.gde.2019.04.013] [Citation(s) in RCA: 134] [Impact Index Per Article: 26.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2019] [Revised: 03/18/2019] [Accepted: 04/15/2019] [Indexed: 01/17/2023]
Abstract
Compacted, transcriptionally repressed chromatin, referred to as heterochromatin, represents a major fraction of the higher eukaryotic genome and exerts pivotal functions of silencing repetitive elements, maintenance of genome stability, and control of gene expression. Among the different histone post-translational modifications (PTMs) associated with heterochromatin, tri-methylation of lysine 9 on histone H3 (H3K9me3) is gaining increased attention. Besides its known role in repressing repetitive elements and non-coding portions of the genome, recent observations indicate H3K9me3 as an important player in silencing lineage-inappropriate genes. The ability of H3K9me3 to influence cell identity challenges the original concept of H3K9me3-marked heterochromatin as mainly a constitutive type of chromatin and provides a further level of understanding of how to modulate cell fate control. Here, we summarize the role of H3K9me3 marked heterochromatin and its dynamics in establishing and maintaining cellular identity.
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Affiliation(s)
- Dario Nicetto
- Institute for Regenerative Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, USA; Penn Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, USA; Dept. Cell and Developmental, Perelman School of Medicine, University of Pennsylvania, Philadelphia, USA
| | - Kenneth S Zaret
- Institute for Regenerative Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, USA; Penn Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, USA; Dept. Cell and Developmental, Perelman School of Medicine, University of Pennsylvania, Philadelphia, USA.
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23
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Grindheim JM, Nicetto D, Donahue G, Zaret KS. Polycomb Repressive Complex 2 Proteins EZH1 and EZH2 Regulate Timing of Postnatal Hepatocyte Maturation and Fibrosis by Repressing Genes With Euchromatic Promoters in Mice. Gastroenterology 2019; 156:1834-1848. [PMID: 30689973 PMCID: PMC6599454 DOI: 10.1053/j.gastro.2019.01.041] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/24/2018] [Revised: 01/02/2019] [Accepted: 01/16/2019] [Indexed: 02/06/2023]
Abstract
BACKGROUND & AIMS Little is known about mechanisms that underlie postnatal hepatocyte maturation and fibrosis at the chromatin level. We investigated the transcription of genes involved in maturation and fibrosis in postnatal hepatocytes of mice, focusing on the chromatin compaction the roles of the Polycomb repressive complex 2 histone methyltransferases EZH1 and EZH2. METHODS Hepatocytes were isolated from mixed background C57BL/6J-C3H mice, as well as mice with liver-specific disruption of Ezh1 and/or Ezh2, at postnatal day 14 and 2 months after birth. Liver tissues were collected and analyzed by RNA sequencing, H3K27me3 chromatin immunoprecipitation sequencing, and sonication-resistant heterochromatin sequencing (a method to map heterochromatin and euchromatin). Liver damage was characterized by histologic analysis. RESULTS We found more than 3000 genes differentially expressed in hepatocytes during liver maturation from postnatal day 14 to month 2 after birth. Disruption of Ezh1 and Ezh2 in livers caused perinatal hepatocytes to differentiate prematurely and to express genes at postnatal day 14 that would normally be induced by month 2 and differentiate prematurely. Loss of Ezh1 and Ezh2 also resulted in liver fibrosis. Genes with H3K27me3-postive and H3K4me3-positive euchromatic promoters were prematurely induced in hepatocytes with loss of Ezh1 and Ezh2-these genes included those that regulate hepatocyte maturation, fibrosis, and genes not specifically associated with the liver lineage. CONCLUSIONS The Polycomb repressive complex 2 proteins EZH1 and EZH2 regulate genes that control hepatocyte maturation and fibrogenesis and genes not specifically associated with the liver lineage by acting at euchromatic promoter regions. EZH1 and EZH2 thereby promote liver homeostasis and prevent liver damage. Strategies to manipulate Polycomb proteins might be used to improve hepatocyte derivation protocols or developed for treatment of patients with liver fibrosis.
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Affiliation(s)
- Jessica Mae Grindheim
- Institute for Regenerative Medicine, University of Pennsylvania, Smilow Center for Translational Research, 3400 Civic Center Blvd, Bldg. 421, Philadelphia, PA 19104-5157, USA.,Penn Epigenetics Institute, University of Pennsylvania, Smilow Center for Translational Research, 3400 Civic Center Blvd, Bldg. 421, Philadelphia, PA 19104-5157, USA.,Dept. Cell and Developmental Biology, University of Pennsylvania, Smilow Center for Translational Research, 3400 Civic Center Blvd, Bldg. 421, Philadelphia, PA 19104-5157, USA.,Dept. of Cancer Biology, University of Pennsylvania, Smilow Center for Translational Research, 3400 Civic Center Blvd, Bldg. 421, Philadelphia, PA 19104-5157, USA.,Perelman School of Medicine, University of Pennsylvania, Smilow Center for Translational Research, 3400 Civic Center Blvd, Bldg. 421, Philadelphia, PA 19104-5157, USA
| | - Dario Nicetto
- Institute for Regenerative Medicine, University of Pennsylvania, Smilow Center for Translational Research, 3400 Civic Center Blvd, Bldg. 421, Philadelphia, PA 19104-5157, USA.,Penn Epigenetics Institute, University of Pennsylvania, Smilow Center for Translational Research, 3400 Civic Center Blvd, Bldg. 421, Philadelphia, PA 19104-5157, USA.,Dept. Cell and Developmental Biology, University of Pennsylvania, Smilow Center for Translational Research, 3400 Civic Center Blvd, Bldg. 421, Philadelphia, PA 19104-5157, USA
| | - Greg Donahue
- Institute for Regenerative Medicine, University of Pennsylvania, Smilow Center for Translational Research, 3400 Civic Center Blvd, Bldg. 421, Philadelphia, PA 19104-5157, USA.,Penn Epigenetics Institute, University of Pennsylvania, Smilow Center for Translational Research, 3400 Civic Center Blvd, Bldg. 421, Philadelphia, PA 19104-5157, USA.,Dept. Cell and Developmental Biology, University of Pennsylvania, Smilow Center for Translational Research, 3400 Civic Center Blvd, Bldg. 421, Philadelphia, PA 19104-5157, USA.,Perelman School of Medicine, University of Pennsylvania, Smilow Center for Translational Research, 3400 Civic Center Blvd, Bldg. 421, Philadelphia, PA 19104-5157, USA
| | - Kenneth S Zaret
- Institute for Regenerative Medicine, University of Pennsylvania, Smilow Center for Translational Research, Philadelphia, Pennsylvania; Penn Epigenetics Institute, University of Pennsylvania, Smilow Center for Translational Research, Philadelphia, Pennsylvania; Department of Cell and Developmental Biology, University of Pennsylvania, Smilow Center for Translational Research, Philadelphia, Pennsylvania; Perelman School of Medicine, University of Pennsylvania, Smilow Center for Translational Research, Philadelphia, Pennsylvania.
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24
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Loubiere V, Martinez AM, Cavalli G. Cell Fate and Developmental Regulation Dynamics by Polycomb Proteins and 3D Genome Architecture. Bioessays 2019; 41:e1800222. [PMID: 30793782 DOI: 10.1002/bies.201800222] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Revised: 12/22/2018] [Indexed: 12/14/2022]
Abstract
Targeted transitions in chromatin states at thousands of genes are essential drivers of eukaryotic development. Therefore, understanding the in vivo dynamics of epigenetic regulators is crucial for deciphering the mechanisms underpinning cell fate decisions. This review illustrates how, in addition to its cell memory function, the Polycomb group of transcriptional regulators orchestrates temporal, cell and tissue-specific expression of master genes during development. These highly sophisticated developmental transitions are dependent on the context- and tissue-specific assembly of the different types of Polycomb Group (PcG) complexes, which regulates their targeting and/or activities on chromatin. Here, an overview is provided of how PcG complexes function at multiple scales to regulate transcription, local chromatin environment, and higher order structures that support normal differentiation and are perturbed in tumorigenesis.
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Affiliation(s)
- Vincent Loubiere
- Institute of Human Genetics, UMR 9002, CNRS and University of Montpellier, 34396, Montpellier, France
| | - Anne-Marie Martinez
- Institute of Human Genetics, UMR 9002, CNRS and University of Montpellier, 34396, Montpellier, France
| | - Giacomo Cavalli
- Institute of Human Genetics, UMR 9002, CNRS and University of Montpellier, 34396, Montpellier, France
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25
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Skourti-Stathaki K, Torlai Triglia E, Warburton M, Voigt P, Bird A, Pombo A. R-Loops Enhance Polycomb Repression at a Subset of Developmental Regulator Genes. Mol Cell 2019; 73:930-945.e4. [PMID: 30709709 PMCID: PMC6414425 DOI: 10.1016/j.molcel.2018.12.016] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Revised: 09/14/2018] [Accepted: 12/14/2018] [Indexed: 12/26/2022]
Abstract
R-loops are three-stranded nucleic acid structures that form during transcription, especially over unmethylated CpG-rich promoters of active genes. In mouse embryonic stem cells (mESCs), CpG-rich developmental regulator genes are repressed by the Polycomb complexes PRC1 and PRC2. Here, we show that R-loops form at a subset of Polycomb target genes, and we investigate their contribution to Polycomb repression. At R-loop-positive genes, R-loop removal leads to decreased PRC1 and PRC2 recruitment and Pol II activation into a productive elongation state, accompanied by gene derepression at nascent and processed transcript levels. Stable removal of PRC2 derepresses R-loop-negative genes, as expected, but does not affect R-loops, PRC1 recruitment, or transcriptional repression of R-loop-positive genes. Our results highlight that Polycomb repression does not occur via one mechanism but consists of different layers of repression, some of which are gene specific. We uncover that one such mechanism is mediated by an interplay between R-loops and RING1B recruitment. R-loops form at a subset of PcG target genes R-loops contribute to PcG recruitment genome-wide Loss of R-loops leads to transcriptional activation of R-loop-positive PcG targets R-loops and PRC1 contribute to transcriptional repression of PcG targets
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Affiliation(s)
- Konstantina Skourti-Stathaki
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, EH9 3BF Edinburgh, UK; Berlin Institute for Medical Systems Biology, Max Delbrueck Centre for Molecular Medicine, Berlin-Buch 13092, Germany.
| | - Elena Torlai Triglia
- Berlin Institute for Medical Systems Biology, Max Delbrueck Centre for Molecular Medicine, Berlin-Buch 13092, Germany
| | - Marie Warburton
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, EH9 3BF Edinburgh, UK
| | - Philipp Voigt
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, EH9 3BF Edinburgh, UK
| | - Adrian Bird
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, EH9 3BF Edinburgh, UK
| | - Ana Pombo
- Berlin Institute for Medical Systems Biology, Max Delbrueck Centre for Molecular Medicine, Berlin-Buch 13092, Germany; Berlin Institute of Health, Berlin, Germany; Institute for Biology, Humboldt-Universitat zu Berlin, Berlin, Germany.
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26
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Shu J, Chen C, Thapa RK, Bian S, Nguyen V, Yu K, Yuan Z, Liu J, Kohalmi SE, Li C, Cui Y. Genome-wide occupancy of histone H3K27 methyltransferases CURLY LEAF and SWINGER in Arabidopsis seedlings. PLANT DIRECT 2019; 3:e00100. [PMID: 31245749 PMCID: PMC6508855 DOI: 10.1002/pld3.100] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Revised: 11/14/2018] [Accepted: 11/19/2018] [Indexed: 05/25/2023]
Abstract
The Polycomb Group (PcG) proteins form two protein complexes, PcG Repressive Complex 1 (PRC1) and PRC2, which are key epigenetic regulators in eukaryotes. PRC2 represses gene expression by catalyzing the trimethylation of histone H3 lysine 27 (H3K27me3). In Arabidopsis (Arabidopsis thaliana), CURLY LEAF (CLF) and SWINGER (SWN) are two major H3K27 methyltransferases and core components of PRC2, playing essential roles in plant growth and development. Despite their importance, genome-wide binding profiles of CLF and SWN have not been determined and compared yet. In this study, we generated transgenic lines expressing GFP-tagged CLF/SWN under their respective native promoters and used them for ChIP-seq analyses to profile the genome-wide distributions of CLF and SWN in Arabidopsis seedlings. We also profiled and compared the global H3K27me3 levels in wild-type (WT) and PcG mutants (clf, swn, and clf swn). Our data show that CLF and SWN bind to almost the same set of genes, except that SWN has a few hundred more targets. Two short DNA sequences, the GAGA-like and Telo-box-like motifs, were found enriched in the CLF and SWN binding regions. The H3K27me3 levels in clf, but not in swn, were markedly reduced compared with WT; and the mark was undetectable in the clf swn double mutant. Further, we profiled the transcriptomes in clf, swn, and clf swn, and compared that with WT. Thus this work provides a useful resource for the plant epigenetics community for dissecting the functions of PRC2 in plant growth and development.
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Affiliation(s)
- Jie Shu
- London Research and Development CentreAgriculture and Agri‐Food CanadaLondonOntarioCanada
- Department of BiologyWestern UniversityLondonOntarioCanada
| | - Chen Chen
- London Research and Development CentreAgriculture and Agri‐Food CanadaLondonOntarioCanada
- Department of BiologyWestern UniversityLondonOntarioCanada
| | - Raj Kumar Thapa
- London Research and Development CentreAgriculture and Agri‐Food CanadaLondonOntarioCanada
- Department of BiologyWestern UniversityLondonOntarioCanada
| | - Shaomin Bian
- London Research and Development CentreAgriculture and Agri‐Food CanadaLondonOntarioCanada
- College of Plant ScienceJilin UniversityChangchunChina
| | - Vi Nguyen
- London Research and Development CentreAgriculture and Agri‐Food CanadaLondonOntarioCanada
| | - Kangfu Yu
- Harrow Research and Development CentreAgriculture and Agri‐Food CanadaHarrowOntarioCanada
| | - Ze‐Chun Yuan
- London Research and Development CentreAgriculture and Agri‐Food CanadaLondonOntarioCanada
| | - Jun Liu
- Guangdong Academy of Agricultural SciencesGuangzhouChina
| | | | - Chenlong Li
- State Key Laboratory of Biocontrol and Guangdong Key Laboratory of Plant ResourcesSchool of Life SciencesSun Yat‐sen UniversityGuangzhouChina
| | - Yuhai Cui
- London Research and Development CentreAgriculture and Agri‐Food CanadaLondonOntarioCanada
- Department of BiologyWestern UniversityLondonOntarioCanada
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Dardalhon-Cuménal D, Deraze J, Dupont CA, Ribeiro V, Coléno-Costes A, Pouch J, Le Crom S, Thomassin H, Debat V, Randsholt NB, Peronnet F. Cyclin G and the Polycomb Repressive complexes PRC1 and PR-DUB cooperate for developmental stability. PLoS Genet 2018; 14:e1007498. [PMID: 29995890 PMCID: PMC6065198 DOI: 10.1371/journal.pgen.1007498] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Revised: 07/27/2018] [Accepted: 06/19/2018] [Indexed: 12/16/2022] Open
Abstract
In Drosophila, ubiquitous expression of a short Cyclin G isoform generates extreme developmental noise estimated by fluctuating asymmetry (FA), providing a model to tackle developmental stability. This transcriptional cyclin interacts with chromatin regulators of the Enhancer of Trithorax and Polycomb (ETP) and Polycomb families. This led us to investigate the importance of these interactions in developmental stability. Deregulation of Cyclin G highlights an organ intrinsic control of developmental noise, linked to the ETP-interacting domain, and enhanced by mutations in genes encoding members of the Polycomb Repressive complexes PRC1 and PR-DUB. Deep-sequencing of wing imaginal discs deregulating CycG reveals that high developmental noise correlates with up-regulation of genes involved in translation and down-regulation of genes involved in energy production. Most Cyclin G direct transcriptional targets are also direct targets of PRC1 and RNAPolII in the developing wing. Altogether, our results suggest that Cyclin G, PRC1 and PR-DUB cooperate for developmental stability.
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Affiliation(s)
- Delphine Dardalhon-Cuménal
- Sorbonne Université, Centre National de la Recherche Scientifique (CNRS),
Institut de Biologie Paris-Seine (IBPS), Laboratory of Developmental Biology
(LBD), Paris, France
| | - Jérôme Deraze
- Sorbonne Université, Centre National de la Recherche Scientifique (CNRS),
Institut de Biologie Paris-Seine (IBPS), Laboratory of Developmental Biology
(LBD), Paris, France
| | - Camille A. Dupont
- Sorbonne Université, Centre National de la Recherche Scientifique (CNRS),
Institut de Biologie Paris-Seine (IBPS), Laboratory of Developmental Biology
(LBD), Paris, France
| | - Valérie Ribeiro
- Sorbonne Université, Centre National de la Recherche Scientifique (CNRS),
Institut de Biologie Paris-Seine (IBPS), Laboratory of Developmental Biology
(LBD), Paris, France
| | - Anne Coléno-Costes
- Sorbonne Université, Centre National de la Recherche Scientifique (CNRS),
Institut de Biologie Paris-Seine (IBPS), Laboratory of Developmental Biology
(LBD), Paris, France
| | - Juliette Pouch
- Institut de biologie de l’Ecole normale supérieure (IBENS), Ecole normale
supérieure, CNRS, INSERM, PSL Université Paris Paris, France
| | - Stéphane Le Crom
- Institut de biologie de l’Ecole normale supérieure (IBENS), Ecole normale
supérieure, CNRS, INSERM, PSL Université Paris Paris, France
- Sorbonne Université, Univ Antilles, Univ Nice Sophia Antipolis, CNRS,
Evolution Paris Seine—Institut de Biologie Paris Seine (EPS - IBPS), Paris,
France
| | - Hélène Thomassin
- Sorbonne Université, Centre National de la Recherche Scientifique (CNRS),
Institut de Biologie Paris-Seine (IBPS), Laboratory of Developmental Biology
(LBD), Paris, France
| | - Vincent Debat
- Institut de Systematique, Evolution, Biodiversité ISYEB UMR 7205, MNHN,
CNRS, Sorbonne Université, EPHE, Muséum national d'Histoire naturelle, Sorbonne
Universités, Paris, France
| | - Neel B. Randsholt
- Sorbonne Université, Centre National de la Recherche Scientifique (CNRS),
Institut de Biologie Paris-Seine (IBPS), Laboratory of Developmental Biology
(LBD), Paris, France
| | - Frédérique Peronnet
- Sorbonne Université, Centre National de la Recherche Scientifique (CNRS),
Institut de Biologie Paris-Seine (IBPS), Laboratory of Developmental Biology
(LBD), Paris, France
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28
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Brockdorff N. Polycomb complexes in X chromosome inactivation. Philos Trans R Soc Lond B Biol Sci 2018; 372:rstb.2017.0021. [PMID: 28947664 PMCID: PMC5627167 DOI: 10.1098/rstb.2017.0021] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/02/2017] [Indexed: 12/13/2022] Open
Abstract
Identifying the critical RNA binding proteins (RBPs) that elicit Xist mediated silencing has been a key goal in X inactivation research. Early studies implicated the Polycomb proteins, a family of factors linked to one of two major multiprotein complexes, PRC1 and PRC2 (Wang 2001 Nat. Genet.28, 371–375 (doi:10.1038/ng574); Silva 2003 Dev. Cell4, 481–495 (doi:10.1016/S1534-5807(03)00068-6); de Napoles 2004 Dev. Cell7, 663–676 (doi:10.1016/j.devcel.2004.10.005); Plath 2003 Science300, 131–135 (doi:10.1126/science.1084274)). PRC1 and PRC2 complexes catalyse specific histone post-translational modifications (PTMs), ubiquitylation of histone H2A at position lysine 119 (H2AK119u1) and methylation of histone H3 at position lysine 27 (H3K27me3), respectively, and accordingly, these modifications are highly enriched over the length of the inactive X chromosome (Xi). A key study proposed that PRC2 subunits bind directly to Xist RNA A-repeat element, a region located at the 5′ end of the transcript known to be required for Xist mediated silencing (Zhao 2008 Science322, 750–756 (doi:10.1126/science.1163045)). Subsequent recruitment of PRC1 was assumed to occur via recognition of PRC2 mediated H3K27me3 by the CBX subunit of PRC1, as has been shown to be the case at other Polycomb target loci (Cao 2002 Science298, 1039–1043 (doi:10.1126/science.1076997)). More recently, several reports have questioned aspects of the prevailing view, both in relation to the mechanism for Polycomb recruitment by Xist RNA and the contribution of the Polycomb pathway to Xist mediated silencing. In this article I provide an overview of our recent progress towards resolving these discrepancies. This article is part of the themed issue ‘X-chromosome inactivation: a tribute to Mary Lyon’.
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Affiliation(s)
- Neil Brockdorff
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
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29
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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
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30
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Becker JS, McCarthy RL, Sidoli S, Donahue G, Kaeding KE, He Z, Lin S, Garcia BA, Zaret KS. Genomic and Proteomic Resolution of Heterochromatin and Its Restriction of Alternate Fate Genes. Mol Cell 2017; 68:1023-1037.e15. [PMID: 29272703 PMCID: PMC5858919 DOI: 10.1016/j.molcel.2017.11.030] [Citation(s) in RCA: 122] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Revised: 10/18/2017] [Accepted: 11/21/2017] [Indexed: 12/24/2022]
Abstract
Heterochromatin is integral to cell identity maintenance by impeding the activation of genes for alternate cell fates. Heterochromatic regions are associated with histone 3 lysine 9 trimethylation (H3K9me3) or H3K27me3, but these modifications are also found in euchromatic regions that permit transcription. We discovered that resistance to sonication is a reliable indicator of the heterochromatin state, and we developed a biophysical method (gradient-seq) to discriminate subtypes of H3K9me3 and H3K27me3 domains in sonication-resistant heterochromatin (srHC) versus euchromatin. These classifications are more accurate than the histone marks alone in predicting transcriptional silence and resistance of alternate fate genes to activation during direct cell conversion. Our proteomics of H3K9me3-marked srHC and functional screens revealed diverse proteins, including RBMX and RBMXL1, that impede gene induction during cellular reprogramming. Isolation of srHC with gradient-seq provides a genome-wide map of chromatin structure, elucidating subtypes of repressed domains that are uniquely predictive of diverse other chromatin properties.
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Affiliation(s)
- Justin S Becker
- Institute for Regenerative Medicine , Perelman School of Medicine, University of Pennsylvania, Smilow Center for Translational Research, 3400 Civic Center Boulevard, Philadelphia, PA 19104, USA; Epigenetics Program , Perelman School of Medicine, University of Pennsylvania, Smilow Center for Translational Research, 3400 Civic Center Boulevard, Philadelphia, PA 19104, USA; Department of Cell and Developmental Biology , Perelman School of Medicine, University of Pennsylvania, Smilow Center for Translational Research, 3400 Civic Center Boulevard, Philadelphia, PA 19104, USA
| | - Ryan L McCarthy
- Institute for Regenerative Medicine , Perelman School of Medicine, University of Pennsylvania, Smilow Center for Translational Research, 3400 Civic Center Boulevard, Philadelphia, PA 19104, USA; Epigenetics Program , Perelman School of Medicine, University of Pennsylvania, Smilow Center for Translational Research, 3400 Civic Center Boulevard, Philadelphia, PA 19104, USA; Department of Cell and Developmental Biology , Perelman School of Medicine, University of Pennsylvania, Smilow Center for Translational Research, 3400 Civic Center Boulevard, Philadelphia, PA 19104, USA
| | - Simone Sidoli
- Epigenetics Program , Perelman School of Medicine, University of Pennsylvania, Smilow Center for Translational Research, 3400 Civic Center Boulevard, Philadelphia, PA 19104, USA; Department of Biochemistry and Molecular Biophysics, Perelman School of Medicine, University of Pennsylvania, Smilow Center for Translational Research, 3400 Civic Center Boulevard, Philadelphia, PA 19104, USA
| | - Greg Donahue
- Institute for Regenerative Medicine , Perelman School of Medicine, University of Pennsylvania, Smilow Center for Translational Research, 3400 Civic Center Boulevard, Philadelphia, PA 19104, USA; Epigenetics Program , Perelman School of Medicine, University of Pennsylvania, Smilow Center for Translational Research, 3400 Civic Center Boulevard, Philadelphia, PA 19104, USA; Department of Cell and Developmental Biology , Perelman School of Medicine, University of Pennsylvania, Smilow Center for Translational Research, 3400 Civic Center Boulevard, Philadelphia, PA 19104, USA
| | - Kelsey E Kaeding
- Institute for Regenerative Medicine , Perelman School of Medicine, University of Pennsylvania, Smilow Center for Translational Research, 3400 Civic Center Boulevard, Philadelphia, PA 19104, USA; Epigenetics Program , Perelman School of Medicine, University of Pennsylvania, Smilow Center for Translational Research, 3400 Civic Center Boulevard, Philadelphia, PA 19104, USA; Department of Cell and Developmental Biology , Perelman School of Medicine, University of Pennsylvania, Smilow Center for Translational Research, 3400 Civic Center Boulevard, Philadelphia, PA 19104, USA
| | - Zhiying He
- Institute for Regenerative Medicine , Perelman School of Medicine, University of Pennsylvania, Smilow Center for Translational Research, 3400 Civic Center Boulevard, Philadelphia, PA 19104, USA; Department of Cell and Developmental Biology , Perelman School of Medicine, University of Pennsylvania, Smilow Center for Translational Research, 3400 Civic Center Boulevard, Philadelphia, PA 19104, USA
| | - Shu Lin
- Epigenetics Program , Perelman School of Medicine, University of Pennsylvania, Smilow Center for Translational Research, 3400 Civic Center Boulevard, Philadelphia, PA 19104, USA; Department of Biochemistry and Molecular Biophysics, Perelman School of Medicine, University of Pennsylvania, Smilow Center for Translational Research, 3400 Civic Center Boulevard, Philadelphia, PA 19104, USA
| | - Benjamin A Garcia
- Epigenetics Program , Perelman School of Medicine, University of Pennsylvania, Smilow Center for Translational Research, 3400 Civic Center Boulevard, Philadelphia, PA 19104, USA; Department of Biochemistry and Molecular Biophysics, Perelman School of Medicine, University of Pennsylvania, Smilow Center for Translational Research, 3400 Civic Center Boulevard, Philadelphia, PA 19104, USA
| | - Kenneth S Zaret
- Institute for Regenerative Medicine , Perelman School of Medicine, University of Pennsylvania, Smilow Center for Translational Research, 3400 Civic Center Boulevard, Philadelphia, PA 19104, USA; Epigenetics Program , Perelman School of Medicine, University of Pennsylvania, Smilow Center for Translational Research, 3400 Civic Center Boulevard, Philadelphia, PA 19104, USA; Department of Cell and Developmental Biology , Perelman School of Medicine, University of Pennsylvania, Smilow Center for Translational Research, 3400 Civic Center Boulevard, Philadelphia, PA 19104, USA.
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31
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Zouaz A, Auradkar A, Delfini MC, Macchi M, Barthez M, Ela Akoa S, Bastianelli L, Xie G, Deng WM, Levine SS, Graba Y, Saurin AJ. The Hox proteins Ubx and AbdA collaborate with the transcription pausing factor M1BP to regulate gene transcription. EMBO J 2017; 36:2887-2906. [PMID: 28871058 DOI: 10.15252/embj.201695751] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Revised: 08/02/2017] [Accepted: 08/07/2017] [Indexed: 11/09/2022] Open
Abstract
In metazoans, the pausing of RNA polymerase II at the promoter (paused Pol II) has emerged as a widespread and conserved mechanism in the regulation of gene transcription. While critical in recruiting Pol II to the promoter, the role transcription factors play in transitioning paused Pol II into productive Pol II is, however, little known. By studying how Drosophila Hox transcription factors control transcription, we uncovered a molecular mechanism that increases productive transcription. We found that the Hox proteins AbdA and Ubx target gene promoters previously bound by the transcription pausing factor M1BP, containing paused Pol II and enriched with promoter-proximal Polycomb Group (PcG) proteins, yet lacking the classical H3K27me3 PcG signature. We found that AbdA binding to M1BP-regulated genes results in reduction in PcG binding, the release of paused Pol II, increases in promoter H3K4me3 histone marks and increased gene transcription. Linking transcription factors, PcG proteins and paused Pol II states, these data identify a two-step mechanism of Hox-driven transcription, with M1BP binding leading to Pol II recruitment followed by AbdA targeting, which results in a change in the chromatin landscape and enhanced transcription.
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Affiliation(s)
- Amel Zouaz
- Aix Marseille Université, CNRS, IBDM, UMR 7288, Marseille, France
| | - Ankush Auradkar
- Aix Marseille Université, CNRS, IBDM, UMR 7288, Marseille, France
| | | | - Meiggie Macchi
- Aix Marseille Université, CNRS, IBDM, UMR 7288, Marseille, France
| | - Marine Barthez
- Aix Marseille Université, CNRS, IBDM, UMR 7288, Marseille, France
| | - Serge Ela Akoa
- Aix Marseille Université, CNRS, IBDM, UMR 7288, Marseille, France
| | - Leila Bastianelli
- MGX-Montpellier GenomiX c/o Institut de Génomique Fonctionnelle, Montpellier, France
| | - Gengqiang Xie
- Department of Biological Science, Florida State University, Tallahassee, FL, USA
| | - Wu-Min Deng
- Department of Biological Science, Florida State University, Tallahassee, FL, USA
| | - Stuart S Levine
- BioMicro Center, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Yacine Graba
- Aix Marseille Université, CNRS, IBDM, UMR 7288, Marseille, France
| | - Andrew J Saurin
- Aix Marseille Université, CNRS, IBDM, UMR 7288, Marseille, France
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32
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Single vector non-leaky gene expression system for Drosophila melanogaster. Sci Rep 2017; 7:6899. [PMID: 28761084 PMCID: PMC5537222 DOI: 10.1038/s41598-017-07282-w] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Accepted: 06/23/2017] [Indexed: 12/28/2022] Open
Abstract
An ideal transgenic gene expression system is inducible, non-leaky, and well tolerated by the target organism. While the former has been satisfactorily realized, leakiness and heavy physiological burden imposed by the existing systems are still prominent hurdles in their successful implementation. Here we describe a new system for non-leaky expression of transgenes in Drosophila. PRExpress is based on a single transgenic construct built from endogenous components, the inducible hsp70 promoter and a multimerized copy of a Polycomb response element (PRE) controlled by epigenetic chromatin regulators of the Polycomb group. We show that this system is non-leaky, rapidly and strongly inducible, and reversible. To make the application of PRExpress user-friendly, we deliver the construct via site-specific integration.
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33
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Chetverina DA, Elizar’ev PV, Lomaev DV, Georgiev PG, Erokhin MM. Control of the gene activity by polycomb and trithorax group proteins in Drosophila. RUSS J GENET+ 2017. [DOI: 10.1134/s1022795417020028] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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34
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Sak A, Kübler D, Bannik K, Groneberg M, Strunz S, Kriehuber R, Stuschke M. Epigenetic silencing and activation of transcription: influence on the radiation sensitivity of glioma cell lines. Int J Radiat Biol 2017; 93:494-506. [DOI: 10.1080/09553002.2017.1270472] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Affiliation(s)
- Ali Sak
- Department of Radiotherapy, University Hospital Essen, Essen, Germany
| | - Dennis Kübler
- Department of Radiotherapy, University Hospital Essen, Essen, Germany
| | - Kristina Bannik
- Department of Radiotherapy, University Hospital Essen, Essen, Germany
| | - Michael Groneberg
- Department of Radiotherapy, University Hospital Essen, Essen, Germany
| | - Sonja Strunz
- Department of Biomathematics and Bioinformatics, Institute of Genetics and Biometry, Leibniz-Institute for Farm Animal Biology, Dummerstorf, Germany
| | - Ralf Kriehuber
- Department of Safety and Radiation Protection, Forschungszentrum Jülich GmbH, Jülich, Germany
| | - Martin Stuschke
- Department of Radiotherapy, University Hospital Essen, Essen, Germany
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35
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Illingworth RS, Hölzenspies JJ, Roske FV, Bickmore WA, Brickman JM. Polycomb enables primitive endoderm lineage priming in embryonic stem cells. eLife 2016; 5. [PMID: 27723457 PMCID: PMC5056788 DOI: 10.7554/elife.14926] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Accepted: 09/23/2016] [Indexed: 12/17/2022] Open
Abstract
Mouse embryonic stem cells (ESCs), like the blastocyst from which they are derived, contain precursors of the epiblast (Epi) and primitive endoderm (PrEn) lineages. While transient in vivo, these precursor populations readily interconvert in vitro. We show that altered transcription is the driver of these coordinated changes, known as lineage priming, in a process that exploits novel polycomb activities. We find that intragenic levels of the polycomb mark H3K27me3 anti-correlate with changes in transcription, irrespective of the gene's developmental trajectory or identity as a polycomb target. In contrast, promoter proximal H3K27me3 is markedly higher for PrEn priming genes. Consequently, depletion of this modification stimulates the degree to which ESCs are primed towards PrEn when challenged to differentiate, but has little effect on gene expression in self-renewing ESC culture. These observations link polycomb with dynamic changes in transcription and stalled lineage commitment, allowing cells to explore alternative choices prior to a definitive decision.
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Affiliation(s)
- Robert S Illingworth
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom
| | - Jurriaan J Hölzenspies
- The Danish Stem Cell Centre - DanStem, University of Copenhagen, Copenhagen, Denmark.,MRC Centre for Regenerative Medicine, Institute for Stem Cell Research, School of Biological Sciences, Univeristy of Edinburgh, Edinburgh, United Kingdom
| | - Fabian V Roske
- The Danish Stem Cell Centre - DanStem, University of Copenhagen, Copenhagen, Denmark
| | - Wendy A Bickmore
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom
| | - Joshua M Brickman
- The Danish Stem Cell Centre - DanStem, University of Copenhagen, Copenhagen, Denmark.,MRC Centre for Regenerative Medicine, Institute for Stem Cell Research, School of Biological Sciences, Univeristy of Edinburgh, Edinburgh, United Kingdom
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36
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Shih HT, Chen WY, Liu KY, Shih ZS, Chen YJ, Hsieh PC, Kuo KL, Huang KH, Hsu PH, Liu YW, Chan SP, Lee HH, Tsai YC, Wu JT. dBRWD3 Regulates Tissue Overgrowth and Ectopic Gene Expression Caused by Polycomb Group Mutations. PLoS Genet 2016; 12:e1006262. [PMID: 27588417 PMCID: PMC5010193 DOI: 10.1371/journal.pgen.1006262] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Accepted: 07/27/2016] [Indexed: 12/20/2022] Open
Abstract
To maintain a particular cell fate, a unique set of genes should be expressed while another set is repressed. One way to repress gene expression is through Polycomb group (PcG) proteins that compact chromatin into a silent configuration. In addition to cell fate maintenance, PcG proteins also maintain normal cell physiology, for example cell cycle. In the absence of PcG, ectopic activation of the PcG-repressed genes leads to developmental defects and malignant tumors. Little is known about the molecular nature of ectopic gene expression; especially what differentiates expression of a given gene in the orthotopic tissue (orthotopic expression) and the ectopic expression of the same gene due to PcG mutations. Here we present that ectopic gene expression in PcG mutant cells specifically requires dBRWD3, a negative regulator of HIRA/Yemanuclein (YEM)-mediated histone variant H3.3 deposition. dBRWD3 mutations suppress both the ectopic gene expression and aberrant tissue overgrowth in PcG mutants through a YEM-dependent mechanism. Our findings identified dBRWD3 as a critical regulator that is uniquely required for ectopic gene expression and aberrant tissue overgrowth caused by PcG mutations. Genetic information is stored in our genomic DNA, and different cells retrieve distinct sets of information from our genome. While it is important to activate genomic regions encoding proteins that are essential for a given cell type, it is equally important to silence genomic regions encoding proteins that are potentially harmful to this type of cells. One of the gene silencing mechanisms frequently used during and after development is mediated by the Polycomb group (PcG) proteins. If this guardian function does not perform correctly due to PcG mutations, genes that are normally silenced—such as oncogenes—are expressed aberrantly. Due to the activation of oncogenes and the loss of other PcG functions, PcG mutant cells often begin to display hallmarks of cancer, such as proliferating beyond control, acquiring stem-cell-like properties, and migrating to distant sites. If the transcriptional mechanisms underlying aberrant gene expression in PcG-mutant cancer cells differ from gene expression in normal cells, we may be able to selectively inhibit the growth of cancer cells without affecting their normal counterparts. Here we show that the difference between these two types of gene expression resides in their sensitivity to dBRWD3, a negative regulator of the deposition of histone H3 variant H3.3. Our results indicate that the inactivation of dBRWD3 or promotion of H3.3 deposition may selectively suppress ectopic gene expression and tumorigenesis driven by mutations in PcG.
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Affiliation(s)
- Hsueh-Tzu Shih
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Wei-Yu Chen
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Kwei-Yan Liu
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Zong-Siou Shih
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Yi-Jyun Chen
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Paul-Chen Hsieh
- Department of Anatomical Pathology, Far Eastern Memorial Hospital, New Taipei City, Taiwan
| | - Kuan-Lin Kuo
- Graduate Institute of Toxicology, National Taiwan University College of Medicine, Taipei, Taiwan
- Department of Urology, National Taiwan University College of Medicine and Hospital, Taipei, Taiwan
| | - Kuo-How Huang
- Department of Urology, National Taiwan University College of Medicine and Hospital, Taipei, Taiwan
| | - Pang-Hung Hsu
- Department of Bioscience and Biotechnology, National Taiwan Ocean University, Keelung, Taiwan
| | - Ya-Wen Liu
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Shih-Peng Chan
- Graduate Institute of Microbiology, College of Medicine, National Taiwan University, Taipei, Taiwan
- Genome and Systems Biology Degree Program, College of Life Science, National Taiwan University, Taipei, Taiwan
| | - Hsiu-Hsiang Lee
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Yu-Chen Tsai
- Department of Life Science and Life Science Center, Tunghai University, Taichung, Taiwan
- * E-mail: (YCT); (JTW)
| | - June-Tai Wu
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
- * E-mail: (YCT); (JTW)
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Laugesen A, Højfeldt JW, Helin K. Role of the Polycomb Repressive Complex 2 (PRC2) in Transcriptional Regulation and Cancer. Cold Spring Harb Perspect Med 2016; 6:cshperspect.a026575. [PMID: 27449971 DOI: 10.1101/cshperspect.a026575] [Citation(s) in RCA: 131] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The chromatin environment is modulated by a machinery of chromatin modifiers, required for the specification and maintenance of cell fate. Many mutations in the machinery have been linked to the development and progression of cancer. In this review, we give a brief introduction to Polycomb group (PcG) proteins, their assembly into Polycomb repressive complexes (PRCs) and the normal physiological roles of these complexes with a focus on the PRC2. We review the many findings of mutations in the PRC2 coding genes, both loss-of-function and gain-of-function, associated with human cancers and discuss potential molecular mechanisms involved in the contribution of PRC2 mutations to cancer development and progression. Finally, we discuss some of the recent advances in developing and testing drugs targeting the PRC2 as well as emerging results from clinical trials using these drugs in the treatment of human cancers.
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Affiliation(s)
- Anne Laugesen
- Biotech Research and Innovation Centre (BRIC), University of Copenhagen, DK-2200 Copenhagen N, Denmark Centre for Epigenetics, University of Copenhagen, DK-2200 Copenhagen N, Denmark The Danish Stem Cell Center (DanStem), University of Copenhagen, DK-2200 Copenhagen N, Denmark
| | - Jonas Westergaard Højfeldt
- Biotech Research and Innovation Centre (BRIC), University of Copenhagen, DK-2200 Copenhagen N, Denmark Centre for Epigenetics, University of Copenhagen, DK-2200 Copenhagen N, Denmark The Danish Stem Cell Center (DanStem), University of Copenhagen, DK-2200 Copenhagen N, Denmark
| | - Kristian Helin
- Biotech Research and Innovation Centre (BRIC), University of Copenhagen, DK-2200 Copenhagen N, Denmark Centre for Epigenetics, University of Copenhagen, DK-2200 Copenhagen N, Denmark The Danish Stem Cell Center (DanStem), University of Copenhagen, DK-2200 Copenhagen N, Denmark
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Kahn TG, Dorafshan E, Schultheis D, Zare A, Stenberg P, Reim I, Pirrotta V, Schwartz YB. Interdependence of PRC1 and PRC2 for recruitment to Polycomb Response Elements. Nucleic Acids Res 2016; 44:10132-10149. [PMID: 27557709 PMCID: PMC5137424 DOI: 10.1093/nar/gkw701] [Citation(s) in RCA: 66] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2016] [Revised: 07/26/2016] [Accepted: 07/28/2016] [Indexed: 12/31/2022] Open
Abstract
Polycomb Group (PcG) proteins are epigenetic repressors essential for control of development and cell differentiation. They form multiple complexes of which PRC1 and PRC2 are evolutionary conserved and obligatory for repression. The targeting of PRC1 and PRC2 is poorly understood and was proposed to be hierarchical and involve tri-methylation of histone H3 (H3K27me3) and/or monoubiquitylation of histone H2A (H2AK118ub). Here, we present a strict test of this hypothesis using the Drosophila model. We discover that neither H3K27me3 nor H2AK118ub is required for targeting PRC complexes to Polycomb Response Elements (PREs). We find that PRC1 can bind PREs in the absence of PRC2 but at many PREs PRC2 requires PRC1 to be targeted. We show that one role of H3K27me3 is to allow PcG complexes anchored at PREs to interact with surrounding chromatin. In contrast, the bulk of H2AK118ub is unrelated to PcG repression. These findings radically change our view of how PcG repression is targeted and suggest that PRC1 and PRC2 can communicate independently of histone modifications.
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Affiliation(s)
- Tatyana G Kahn
- Department of Molecular Biology, Umeå University, Umeå, 901 87, Sweden
| | - Eshagh Dorafshan
- Department of Molecular Biology, Umeå University, Umeå, 901 87, Sweden
| | - Dorothea Schultheis
- Friedrich-Alexander University of Erlangen-Nürnberg, Department of Biology, Division of Developmental Biology, Erlangen, D-91058, Germany
| | - Aman Zare
- Department of Molecular Biology, Umeå University, Umeå, 901 87, Sweden
| | - Per Stenberg
- Department of Molecular Biology, Umeå University, Umeå, 901 87, Sweden.,Division of CBRN Defense and Security, Swedish Defense Research Agency, FOI, Umeå, 906 21, Sweden
| | - Ingolf Reim
- Friedrich-Alexander University of Erlangen-Nürnberg, Department of Biology, Division of Developmental Biology, Erlangen, D-91058, Germany
| | - Vincenzo Pirrotta
- Department of Molecular Biology and Biochemistry, Rutgers University, Piscataway, NJ 08854, USA
| | - Yuri B Schwartz
- Department of Molecular Biology, Umeå University, Umeå, 901 87, Sweden
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Yu CW, Chang KY, Wu K. Genome-Wide Analysis of Gene Regulatory Networks of the FVE-HDA6-FLD Complex in Arabidopsis. FRONTIERS IN PLANT SCIENCE 2016; 7:555. [PMID: 27200029 PMCID: PMC4848314 DOI: 10.3389/fpls.2016.00555] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Accepted: 04/11/2016] [Indexed: 05/18/2023]
Abstract
FVE/MSI4 is a homolog of the mammalian RbAp48 protein. We found that FVE regulates flowering time by repressing FLC through decreasing histone H3K4 trimethylation and H3 acetylation. Furthermore, FVE interacts with the histone deacetylase HDA6 and the histone demethylase FLD, suggesting that these proteins may form a protein complex to regulate flowering time. To further investigate the function of the FVE-FLD-HDA6 complex, we compared the gene expression profiles of fve, fld, and hda6 mutant plants by using RNA-seq analysis. Among the mis-regulated genes found in fve plants, 51.8 and 36.5% of them were also mis-regulated in fld and hda6 plants, respectively, suggesting that FVE, HDA6, and FLD may regulate the gene expression in the same developmental processes in Arabidopsis. Gene ontology analysis revealed that among 383 genes co-regulated by FVE, HDA6, and FLD, 15.6% of them are involved in transcription, 8.2% in RNA metabolic process, 7.7% in response to abiotic stress, and 6.3% in hormone stimulus. Taken together, these results indicate that HDA6, FVE, and FLD co-regulate the gene expression in multiple development processes and pathways.
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40
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Becker JS, Nicetto D, Zaret KS. H3K9me3-Dependent Heterochromatin: Barrier to Cell Fate Changes. Trends Genet 2015; 32:29-41. [PMID: 26675384 DOI: 10.1016/j.tig.2015.11.001] [Citation(s) in RCA: 290] [Impact Index Per Article: 32.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Revised: 10/30/2015] [Accepted: 11/02/2015] [Indexed: 01/26/2023]
Abstract
Establishing and maintaining cell identity depends on the proper regulation of gene expression, as specified by transcription factors and reinforced by epigenetic mechanisms. Among the epigenetic mechanisms, heterochromatin formation is crucial for the preservation of genome stability and the cell type-specific silencing of genes. The heterochromatin-associated histone mark H3K9me3, although traditionally associated with the noncoding portions of the genome, has emerged as a key player in repressing lineage-inappropriate genes and shielding them from activation by transcription factors. Here we describe the role of H3K9me3 heterochromatin in impeding the reprogramming of cell identity and the mechanisms by which H3K9me3 is reorganized during development and cell fate determination.
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Affiliation(s)
- Justin S Becker
- Institute for Regenerative Medicine, Epigenetics Program, and Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Smilow Center for Translational Research, 3400 Civic Center Boulevard, Philadelphia, PA 19104, USA
| | - Dario Nicetto
- Institute for Regenerative Medicine, Epigenetics Program, and Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Smilow Center for Translational Research, 3400 Civic Center Boulevard, Philadelphia, PA 19104, USA
| | - Kenneth S Zaret
- Institute for Regenerative Medicine, Epigenetics Program, and Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Smilow Center for Translational Research, 3400 Civic Center Boulevard, Philadelphia, PA 19104, USA.
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41
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Abdouh M, Hanna R, El Hajjar J, Flamier A, Bernier G. The Polycomb Repressive Complex 1 Protein BMI1 Is Required for Constitutive Heterochromatin Formation and Silencing in Mammalian Somatic Cells. J Biol Chem 2015; 291:182-97. [PMID: 26468281 DOI: 10.1074/jbc.m115.662403] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Indexed: 01/08/2023] Open
Abstract
The polycomb repressive complex 1 (PRC1), containing the core BMI1 and RING1A/B proteins, mono-ubiquitinylates histone H2A (H2A(ub)) and is associated with silenced developmental genes at facultative heterochromatin. It is, however, assumed that the PRC1 is excluded from constitutive heterochromatin in somatic cells based on work performed on mouse embryonic stem cells and oocytes. We show here that BMI1 is required for constitutive heterochromatin formation and silencing in human and mouse somatic cells. BMI1 was highly enriched at intergenic and pericentric heterochromatin, co-immunoprecipitated with the architectural heterochromatin proteins HP1, DEK1, and ATRx, and was required for their localization. In contrast, BRCA1 localization was BMI1-independent and partially redundant with that of BMI1 for H2A(ub) deposition, constitutive heterochromatin formation, and silencing. These observations suggest a dynamic and developmentally regulated model of PRC1 occupancy at constitutive heterochromatin, and where BMI1 function in somatic cells is to stabilize the repetitive genome.
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Affiliation(s)
- Mohamed Abdouh
- From the Department of Neurosciences, University of Montreal, and The Stem Cell and Developmental Biology Laboratory, Hôpital Maisonneuve-Rosemont, 5415 Boul. l'Assomption, Montreal H1T 2M4, Canada
| | - Roy Hanna
- From the Department of Neurosciences, University of Montreal, and The Stem Cell and Developmental Biology Laboratory, Hôpital Maisonneuve-Rosemont, 5415 Boul. l'Assomption, Montreal H1T 2M4, Canada
| | - Jida El Hajjar
- From the Department of Neurosciences, University of Montreal, and The Stem Cell and Developmental Biology Laboratory, Hôpital Maisonneuve-Rosemont, 5415 Boul. l'Assomption, Montreal H1T 2M4, Canada
| | - Anthony Flamier
- From the Department of Neurosciences, University of Montreal, and The Stem Cell and Developmental Biology Laboratory, Hôpital Maisonneuve-Rosemont, 5415 Boul. l'Assomption, Montreal H1T 2M4, Canada
| | - Gilbert Bernier
- From the Department of Neurosciences, University of Montreal, and The Stem Cell and Developmental Biology Laboratory, Hôpital Maisonneuve-Rosemont, 5415 Boul. l'Assomption, Montreal H1T 2M4, Canada
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42
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Chemical “Diversity” of Chromatin Through Histone Variants and Histone Modifications. ACTA ACUST UNITED AC 2015. [DOI: 10.1007/s40610-015-0005-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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43
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Englert NA, Luo G, Goldstein JA, Surapureddi S. Epigenetic modification of histone 3 lysine 27: mediator subunit MED25 is required for the dissociation of polycomb repressive complex 2 from the promoter of cytochrome P450 2C9. J Biol Chem 2014; 290:2264-78. [PMID: 25391650 DOI: 10.1074/jbc.m114.579474] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
The Mediator complex is vital for the transcriptional regulation of eukaryotic genes. Mediator binds to nuclear receptors at target response elements and recruits chromatin-modifying enzymes and RNA polymerase II. Here, we examine the involvement of Mediator subunit MED25 in the epigenetic regulation of human cytochrome P450 2C9 (CYP2C9). MED25 is recruited to the CYP2C9 promoter through association with liver-enriched HNF4α, and we show that MED25 influences the H3K27 status of the HNF4α binding region. This region was enriched for the activating marker H3K27ac and histone acetyltransferase CREBBP after MED25 overexpression but was trimethylated when MED25 expression was silenced. The epigenetic regulator Polycomb repressive complex (PRC2), which represses expression by methylating H3K27, plays an important role in target gene regulation. Silencing MED25 correlated with increased association of PRC2 not only with the promoter region chromatin but with HNF4α itself. We confirmed the involvement of MED25 for fully functional preinitiation complex recruitment and transcriptional output in vitro. Formaldehyde-assisted isolation of regulatory elements (FAIRE) revealed chromatin conformation changes that were reliant on MED25, indicating that MED25 induced a permissive chromatin state that reflected increases in CYP2C9 mRNA. For the first time, we showed evidence that a functionally relevant human gene is transcriptionally regulated by HNF4α via MED25 and PRC2. CYP2C9 is important for the metabolism of many exogenous chemicals including pharmaceutical drugs as well as endogenous substrates. Thus, MED25 is important for regulating the epigenetic landscape resulting in transcriptional activation of a highly inducible gene, CYP2C9.
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Affiliation(s)
- Neal A Englert
- From the Laboratory of Toxicology and Pharmacology, NIEHS, National Institutes of Health, Research Triangle Park, North Carolina 27709
| | - George Luo
- From the Laboratory of Toxicology and Pharmacology, NIEHS, National Institutes of Health, Research Triangle Park, North Carolina 27709
| | - Joyce A Goldstein
- From the Laboratory of Toxicology and Pharmacology, NIEHS, National Institutes of Health, Research Triangle Park, North Carolina 27709
| | - Sailesh Surapureddi
- From the Laboratory of Toxicology and Pharmacology, NIEHS, National Institutes of Health, Research Triangle Park, North Carolina 27709
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44
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Grossniklaus U, Paro R. Transcriptional silencing by polycomb-group proteins. Cold Spring Harb Perspect Biol 2014; 6:a019331. [PMID: 25367972 DOI: 10.1101/cshperspect.a019331] [Citation(s) in RCA: 168] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Polycomb-group (PcG) genes encode chromatin proteins involved in stable and heritable transcriptional silencing. PcG proteins participate in distinct multimeric complexes that deposit, or bind to, specific histone modifications (e.g., H3K27me3 and H2AK119ub1) to prevent gene activation and maintain repressed chromatin domains. PcG proteins are evolutionary conserved and play a role in processes ranging from vernalization and seed development in plants, over X-chromosome inactivation in mammals, to the maintenance of stem cell identity. PcG silencing is medically relevant as it is often observed in human disorders, including cancer, and tissue regeneration, which involve the reprogramming of PcG-controlled target genes.
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Affiliation(s)
- Ueli Grossniklaus
- Institute of Plant Biology and Zürich-Basel Plant Science Center, University of Zürich, CH-8008 Zürich, Switzerland
| | - Renato Paro
- Department of Biosystems Science and Engineering, ETH Zürich, 4058 Basel, Switzerland
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45
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Derkacheva M, Hennig L. Variations on a theme: Polycomb group proteins in plants. JOURNAL OF EXPERIMENTAL BOTANY 2014; 65:2769-84. [PMID: 24336446 DOI: 10.1093/jxb/ert410] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Polycomb group (PcG) proteins evolved early in evolution, probably in the common ancestor of animals and plants. In some unicellular organisms, such as Chlamydomonas and Tetrahymena, PcG proteins silence genes in heterochromatin, suggesting an ancestral function in genome defence. In angiosperms, the PcG system controls many developmental transitions. A PcG function in the vernalization response evolved especially in Brassicaceaea. Thus, the role of PcG proteins has changed during evolution to match novel needs. Recent studies identified many proteins associated with plant PcG protein complexes. Possible functions of these interactions are discussed here. We highlight recent findings about recruitment of PcG proteins in plants in comparison with animal system. Through the new data, a picture emerges in which PcG protein complexes do not function in sequential linear pathways but as dynamically interacting networks allowing stabilizing feedback loops. We discuss how the interplay between different PcG protein complexes can enable establishment, maintenance, and epigenetic inheritance of H3K27me3.
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Affiliation(s)
- Maria Derkacheva
- Department of Plant Biology and Forest Genetics, Uppsala BioCenter, Swedish University of Agricultural Sciences and Linnean Center for Plant Biology, SE-75007 Uppsala, Sweden Department of Biology and Zurich-Basel Plant Science Center, ETH Zurich, CH-8092, Zurich, Switzerland
| | - Lars Hennig
- Department of Plant Biology and Forest Genetics, Uppsala BioCenter, Swedish University of Agricultural Sciences and Linnean Center for Plant Biology, SE-75007 Uppsala, Sweden Department of Biology and Zurich-Basel Plant Science Center, ETH Zurich, CH-8092, Zurich, Switzerland Science for Life Laboratory, SE-75007 Uppsala, Sweden
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46
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Orsi GA, Kasinathan S, Hughes KT, Saminadin-Peter S, Henikoff S, Ahmad K. High-resolution mapping defines the cooperative architecture of Polycomb response elements. Genome Res 2014; 24:809-20. [PMID: 24668908 PMCID: PMC4009610 DOI: 10.1101/gr.163642.113] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Polycomb-mediated chromatin repression modulates gene expression during development in metazoans. Binding of multiple sequence-specific factors at discrete Polycomb response elements (PREs) is thought to recruit repressive complexes that spread across an extended chromatin domain. To dissect the structure of PREs, we applied high-resolution mapping of nonhistone chromatin proteins in native chromatin of Drosophila cells. Analysis of occupied sites reveal interactions between transcription factors that stabilize Polycomb anchoring to DNA, and implicate the general transcription factor ADF1 as a novel PRE component. By comparing two Drosophila cell lines with differential chromatin states, we provide evidence that repression is accomplished by enhanced Polycomb recruitment both to PREs and to target promoters of repressed genes. These results suggest that the stability of multifactor complexes at promoters and regulatory elements is a crucial aspect of developmentally regulated gene expression.
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Affiliation(s)
- Guillermo A Orsi
- Department of Biological Chemistry & Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115, USA
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47
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Schwartz YB, Pirrotta V. A new world of Polycombs: unexpected partnerships and emerging functions. Nat Rev Genet 2013; 14:853-64. [PMID: 24217316 DOI: 10.1038/nrg3603] [Citation(s) in RCA: 212] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Polycomb group (PcG) proteins are epigenetic repressors that are essential for the transcriptional control of cell differentiation and development. PcG-mediated repression is associated with specific post-translational histone modifications and is thought to involve both biochemical and physical modulation of chromatin structure. Recent advances show that PcG complexes comprise a multiplicity of variants and are far more biochemically diverse than previously thought. The importance of these new PcG complexes for normal development and disease, their targeting mechanisms and their shifting roles in the course of differentiation are now the subject of investigation and the focus of this Review.
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Affiliation(s)
- Yuri B Schwartz
- Department of Molecular Biology, Umeå University, Byggnad 6L, Norrlands University Hospital, 901 87 Umeå, Sweden
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48
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Johnson A, Wu R, Peetz M, Gygi SP, Moazed D. Heterochromatic gene silencing by activator interference and a transcription elongation barrier. J Biol Chem 2013; 288:28771-82. [PMID: 23940036 PMCID: PMC3789973 DOI: 10.1074/jbc.m113.460071] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Heterochromatin silences transcription, contributing to development, differentiation, and genome stability in eukaryotic organisms. Budding yeast heterochromatic silencing is strictly dependent on the silent information regulator (SIR) complex composed of the Sir2 histone deacetylase and the chromatin-interacting proteins Sir3 and Sir4. We use reconstituted SIR heterochromatin to characterize the steps in transcription that are disrupted to achieve silencing. Transcriptional activator binding is permitted before and after heterochromatin assembly. A comprehensive proteomic approach identified heterochromatin-mediated disruption of activator interactions with coactivator complexes. We also find that if RNA polymerase II (Pol II) is allowed to initiate transcription, the SIR complex blocks elongation on chromatin while maintaining Pol II in a halted conformation. This Pol II elongation barrier functions for even one nucleosome, is more effective when assembled with multiple nucleosomes, and is sensitive to a histone mutation that is known to disrupt silencing. This dual mechanism of silencing suggests a conserved principle of heterochromatin in assembling a specific structure that targets multiple steps to achieve repression.
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49
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Soshnev AA, Baxley RM, Manak JR, Tan K, Geyer PK. The insulator protein Suppressor of Hairy-wing is an essential transcriptional repressor in the Drosophila ovary. Development 2013; 140:3613-23. [PMID: 23884443 DOI: 10.1242/dev.094953] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Suppressor of Hairy-wing [Su(Hw)] is a DNA-binding factor required for gypsy insulator function and female germline development in Drosophila. The insulator function of the gypsy retrotransposon depends on Su(Hw) binding to clustered Su(Hw) binding sites (SBSs) and recruitment of the insulator proteins Centrosomal Protein 190 kD (CP190) and Modifier of mdg4 67.2 kD (Mod67.2). By contrast, the Su(Hw) germline function involves binding to non-clustered SBSs and does not require CP190 or Mod67.2. Here, we identify Su(Hw) target genes, using genome-wide analyses in the ovary to uncover genes with an ovary-bound SBS that are misregulated upon Su(Hw) loss. Most Su(Hw) target genes demonstrate enriched expression in the wild-type CNS. Loss of Su(Hw) leads to increased expression of these CNS-enriched target genes in the ovary and other tissues, suggesting that Su(Hw) is a repressor of neural genes in non-neural tissues. Among the Su(Hw) target genes is RNA-binding protein 9 (Rbp9), a member of the ELAV/Hu gene family. Su(Hw) regulation of Rbp9 appears to be insulator independent, as Rbp9 expression is unchanged in a genetic background that compromises the functions of the CP190 and Mod67.2 insulator proteins, even though both localize to Rbp9 SBSs. Rbp9 misregulation is central to su(Hw)(-/-) sterility, as Rbp9(+/-), su(Hw)(-/-) females are fertile. Eggs produced by Rbp9(+/-), su(Hw)(-/-) females show patterning defects, revealing a somatic requirement for Su(Hw) in the ovary. Our studies demonstrate that Su(Hw) is a versatile transcriptional regulatory protein with an essential developmental function involving transcriptional repression.
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Affiliation(s)
- Alexey A Soshnev
- Interdisciplinary Graduate Program in Molecular and Cellular Biology, University of Iowa, Iowa City, IA 52242, USA
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50
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Lindner M, Simonini S, Kooiker M, Gagliardini V, Somssich M, Hohenstatt M, Simon R, Grossniklaus U, Kater MM. TAF13 interacts with PRC2 members and is essential for Arabidopsis seed development. Dev Biol 2013; 379:28-37. [PMID: 23506837 DOI: 10.1016/j.ydbio.2013.03.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2012] [Revised: 02/28/2013] [Accepted: 03/01/2013] [Indexed: 11/24/2022]
Abstract
TBP-Associated Factors (TAFs) are components of complexes like TFIID, TFTC, SAGA/STAGA and SMAT that are important for the activation of transcription, either by establishing the basic transcription machinery or by facilitating histone acetylation. However, in Drosophila embryos several TAFs were shown to be associated with the Polycomb Repressive Complex 1 (PRC1), even though the role of this interaction remains unclear. Here we show that in Arabidopsis TAF13 interacts with MEDEA and SWINGER, both members of a plant variant of Polycomb Repressive Complex 2 (PRC2). PRC2 variants play important roles during the plant life cycle, including seed development. The taf13 mutation causes seed defects, showing embryo arrest at the 8-16 cell stage and over-proliferation of the endosperm in the chalazal region, which is typical for Arabidopsis PRC2 mutants. Our data suggest that TAF13 functions together with PRC2 in transcriptional regulation during seed development.
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Affiliation(s)
- Matias Lindner
- Dipartimento di BioScienze, Università degli Studi di Milano, Via Celoria 26, 20133 Milan, Italy
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