51
|
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: 185] [Impact Index Per Article: 61.7] [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.
Collapse
Affiliation(s)
| | - Robert J Klose
- Department of Biochemistry, University of Oxford, Oxford, UK.
| |
Collapse
|
52
|
Pauli S, Berger H, Ufartes R, Borchers A. Comparing a Novel Malformation Syndrome Caused by Pathogenic Variants in FBRSL1 to AUTS2 Syndrome. Front Cell Dev Biol 2021; 9:779009. [PMID: 34805182 PMCID: PMC8602103 DOI: 10.3389/fcell.2021.779009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Accepted: 10/22/2021] [Indexed: 11/13/2022] Open
Abstract
Truncating variants in specific exons of Fibrosin-like protein 1 (FBRSL1) were recently reported to cause a novel malformation and intellectual disability syndrome. The clinical spectrum includes microcephaly, facial dysmorphism, cleft palate, skin creases, skeletal anomalies and contractures, postnatal growth retardation, global developmental delay as well as respiratory problems, hearing impairment and heart defects. The function of FBRSL1 is largely unknown, but pathogenic variants in the FBRSL1 paralog Autism Susceptibility Candidate 2 (AUTS2) are causative for an intellectual disability syndrome with microcephaly (AUTS2 syndrome). Some patients with AUTS2 syndrome also show additional symptoms like heart defects and contractures overlapping with the phenotype presented by patients with FBRSL1 mutations. For AUTS2, a dual function, depending on different isoforms, was described and suggested for FBRSL1. Both, nuclear FBRSL1 and AUTS2 are components of the Polycomb subcomplexes PRC1.3 and PRC1.5. These complexes have essential roles in developmental processes, cellular differentiation and proliferation by regulating gene expression via histone modification. In addition, cytoplasmic AUTS2 controls neural development, neuronal migration and neurite extension by regulating the cytoskeleton. Here, we review recent data on FBRSL1 in respect to previously published data on AUTS2 to gain further insights into its molecular function, its role in development as well as its impact on human genetics.
Collapse
Affiliation(s)
- Silke Pauli
- Institute of Human Genetics, University Medical Center Göttingen, Göttingen, Germany
| | - Hanna Berger
- Faculty of Biology, Molecular Embryology, Philipps‐University Marburg, Marburg, Germany
| | - Roser Ufartes
- Institute of Human Genetics, University Medical Center Göttingen, Göttingen, Germany
| | - Annette Borchers
- Faculty of Biology, Molecular Embryology, Philipps‐University Marburg, Marburg, Germany
| |
Collapse
|
53
|
Trotman JB, Braceros KCA, Cherney RE, Murvin MM, Calabrese JM. The control of polycomb repressive complexes by long noncoding RNAs. WILEY INTERDISCIPLINARY REVIEWS. RNA 2021; 12:e1657. [PMID: 33861025 PMCID: PMC8500928 DOI: 10.1002/wrna.1657] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 01/12/2021] [Accepted: 03/19/2021] [Indexed: 02/06/2023]
Abstract
The polycomb repressive complexes 1 and 2 (PRCs; PRC1 and PRC2) are conserved histone-modifying enzymes that often function cooperatively to repress gene expression. The PRCs are regulated by long noncoding RNAs (lncRNAs) in complex ways. On the one hand, specific lncRNAs cause the PRCs to engage with chromatin and repress gene expression over genomic regions that can span megabases. On the other hand, the PRCs bind RNA with seemingly little sequence specificity, and at least in the case of PRC2, direct RNA-binding has the effect of inhibiting the enzyme. Thus, some RNAs appear to promote PRC activity, while others may inhibit it. The reasons behind this apparent dichotomy are unclear. The most potent PRC-activating lncRNAs associate with chromatin and are predominantly unspliced or harbor unusually long exons. Emerging data imply that these lncRNAs promote PRC activity through internal RNA sequence elements that arise and disappear rapidly in evolutionary time. These sequence elements may function by interacting with common subsets of RNA-binding proteins that recruit or stabilize PRCs on chromatin. This article is categorized under: RNA Interactions with Proteins and Other Molecules > Protein-RNA Recognition RNA Interactions with Proteins and Other Molecules > RNA-Protein Complexes RNA Interactions with Proteins and Other Molecules > Protein-RNA Interactions: Functional Implications.
Collapse
Affiliation(s)
- Jackson B. Trotman
- Department of Pharmacology and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Keean C. A. Braceros
- Department of Pharmacology and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
- Curriculum in Mechanistic, Interdisciplinary Studies of Biological Systems, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Rachel E. Cherney
- Department of Pharmacology and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
- Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - McKenzie M. Murvin
- Department of Pharmacology and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
- Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - J. Mauro Calabrese
- Department of Pharmacology and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| |
Collapse
|
54
|
Peng X, Feng G, Zhang Y, Sun Y. PRC1 Stabilizes Cardiac Contraction by Regulating Cardiac Sarcomere Assembly and Cardiac Conduction System Construction. Int J Mol Sci 2021; 22:11368. [PMID: 34768802 PMCID: PMC8583368 DOI: 10.3390/ijms222111368] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Revised: 10/15/2021] [Accepted: 10/17/2021] [Indexed: 01/01/2023] Open
Abstract
Cardiac development is a complex process that is strictly controlled by various factors, including PcG protein complexes. Several studies have reported the critical role of PRC2 in cardiogenesis. However, little is known about the regulation mechanism of PRC1 in embryonic heart development. To gain more insight into the mechanistic role of PRC1 in cardiogenesis, we generated a PRC1 loss-of-function zebrafish line by using the CRISPR/Cas9 system targeting rnf2, a gene encoding the core subunit shared by all PRC1 subfamilies. Our results revealed that Rnf2 is not involved in cardiomyocyte differentiation and heart tube formation, but that it is crucial to maintaining regular cardiac contraction. Further analysis suggested that Rnf2 loss-of-function disrupted cardiac sarcomere assembly through the ectopic activation of non-cardiac sarcomere genes in the developing heart. Meanwhile, Rnf2 deficiency disrupts the construction of the atrioventricular canal and the sinoatrial node by modulating the expression of bmp4 and other atrioventricular canal marker genes, leading to an impaired cardiac conduction system. The disorganized cardiac sarcomere and defective cardiac conduction system together contribute to defective cardiac contraction. Our results emphasize the critical role of PRC1 in the cardiac development.
Collapse
Affiliation(s)
- Xixia Peng
- Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China; (X.P.); (G.F.); (Y.Z.)
- College of Advanced Agricultural Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Gang Feng
- Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China; (X.P.); (G.F.); (Y.Z.)
- College of Advanced Agricultural Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yanyong Zhang
- Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China; (X.P.); (G.F.); (Y.Z.)
- College of Advanced Agricultural Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yuhua Sun
- Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China; (X.P.); (G.F.); (Y.Z.)
- The Innovation of Seed Design, Chinese Academy of Sciences, Wuhan 430072, China
| |
Collapse
|
55
|
Peeters JGC, DuPage M. A PRC1-RNF2 knockout punch for cancer. NATURE CANCER 2021; 2:996-997. [PMID: 35121885 DOI: 10.1038/s43018-021-00270-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Janneke G C Peeters
- Division of Immunology and Pathogenesis, Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, USA
| | - Michel DuPage
- Division of Immunology and Pathogenesis, Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, USA.
| |
Collapse
|
56
|
Zhang Y, Liu T, Yuan F, Garcia-Martinez L, Lee KD, Stransky S, Sidoli S, Verdun RE, Zhang Y, Wang Z, Morey L. The Polycomb protein RING1B enables estrogen-mediated gene expression by promoting enhancer-promoter interaction and R-loop formation. Nucleic Acids Res 2021; 49:9768-9782. [PMID: 34428304 PMCID: PMC8464076 DOI: 10.1093/nar/gkab723] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Revised: 07/19/2021] [Accepted: 08/11/2021] [Indexed: 12/22/2022] Open
Abstract
Polycomb complexes have traditionally been prescribed roles as transcriptional repressors, though increasing evidence demonstrate they can also activate gene expression. However, the mechanisms underlying positive gene regulation mediated by Polycomb proteins are poorly understood. Here, we show that RING1B, a core component of Polycomb Repressive Complex 1, regulates enhancer-promoter interaction of the bona fide estrogen-activated GREB1 gene. Systematic characterization of RNA:DNA hybrid formation (R-loops), nascent transcription and RNA Pol II activity upon estrogen administration revealed a key role of RING1B in gene activation by regulating R-loop formation and RNA Pol II elongation. We also found that the estrogen receptor alpha (ERα) and RNA are both necessary for full RING1B recruitment to estrogen-activated genes. Notably, RING1B recruitment was mostly unaffected upon RNA Pol II depletion. Our findings delineate the functional interplay between RING1B, RNA and ERα to safeguard chromatin architecture perturbations required for estrogen-mediated gene regulation and highlight the crosstalk between steroid hormones and Polycomb proteins to regulate oncogenic programs.
Collapse
Affiliation(s)
- Yusheng Zhang
- Sylvester Comprehensive Cancer Center, Biomedical Research Building, 1501 NW 10th Avenue, Miami, FL 33136, USA.,Department of Human Genetics, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Tong Liu
- Department of Computer Science, University of Miami, 1365 Memorial Drive, P.O. Box 248154, Coral Gables, FL 33124, USA
| | - Fenghua Yuan
- Sylvester Comprehensive Cancer Center, Biomedical Research Building, 1501 NW 10th Avenue, Miami, FL 33136, USA.,Department of Biochemistry and Molecular Biology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Liliana Garcia-Martinez
- Sylvester Comprehensive Cancer Center, Biomedical Research Building, 1501 NW 10th Avenue, Miami, FL 33136, USA.,Department of Human Genetics, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Kyutae D Lee
- Sylvester Comprehensive Cancer Center, Biomedical Research Building, 1501 NW 10th Avenue, Miami, FL 33136, USA.,Department of Human Genetics, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Stephanie Stransky
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Simone Sidoli
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Ramiro E Verdun
- Sylvester Comprehensive Cancer Center, Biomedical Research Building, 1501 NW 10th Avenue, Miami, FL 33136, USA.,Division of Hematology, Department of Medicine, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Yanbin Zhang
- Sylvester Comprehensive Cancer Center, Biomedical Research Building, 1501 NW 10th Avenue, Miami, FL 33136, USA.,Department of Biochemistry and Molecular Biology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Zheng Wang
- Department of Computer Science, University of Miami, 1365 Memorial Drive, P.O. Box 248154, Coral Gables, FL 33124, USA
| | - Lluis Morey
- Sylvester Comprehensive Cancer Center, Biomedical Research Building, 1501 NW 10th Avenue, Miami, FL 33136, USA.,Department of Human Genetics, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| |
Collapse
|
57
|
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: 13] [Impact Index Per Article: 4.3] [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.
Collapse
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;
| |
Collapse
|
58
|
Liu S, Trejo-Arellano MS, Qiu Y, Eklund DM, Köhler C, Hennig L. H2A ubiquitination is essential for Polycomb Repressive Complex 1-mediated gene regulation in Marchantia polymorpha. Genome Biol 2021; 22:253. [PMID: 34465381 PMCID: PMC8408974 DOI: 10.1186/s13059-021-02476-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2021] [Accepted: 08/23/2021] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND Polycomb repressive complex 1 (PRC1) and PRC2 are chromatin regulators maintaining transcriptional repression. The deposition of H3 lysine 27 tri-methylation (H3K27me3) by PRC2 is known to be required for transcriptional repression, whereas the contribution of H2A ubiquitination (H2Aub) in the Polycomb repressive system remains unclear in plants. RESULTS We directly test the requirement of H2Aub for gene regulation in Marchantia polymorpha by generating point mutations in H2A that prevent ubiquitination by PRC1. These mutants show reduced H3K27me3 levels on the same target sites as mutants defective in PRC1 subunits MpBMI1 and the homolog MpBMI1L, revealing that PRC1-catalyzed H2Aub is essential for Polycomb system function. Furthermore, by comparing transcriptome data between mutants in MpH2A and MpBMI1/1L, we demonstrate that H2Aub contributes to the PRC1-mediated transcriptional level of genes and transposable elements. CONCLUSION Together, our data demonstrates that H2Aub plays a direct role in H3K27me3 deposition and is required for PRC1-mediated transcriptional changes in both genes and transposable elements in Marchantia.
Collapse
Affiliation(s)
- Shujing Liu
- Department of Plant Biology, Swedish University of Agricultural Sciences and Linnean Center for Plant Biology, 75007, Uppsala, Sweden.
| | - Minerva S Trejo-Arellano
- Department of Plant Biology, Swedish University of Agricultural Sciences and Linnean Center for Plant Biology, 75007, Uppsala, Sweden
- Present address: Department of Cell and Developmental Biology, John Innes Centre, Norwich, NR4 7UH, UK
| | - Yichun Qiu
- Department of Plant Biology, Swedish University of Agricultural Sciences and Linnean Center for Plant Biology, 75007, Uppsala, Sweden
- Max Planck Institute of Molecular Plant Physiology, Potsdam, 14476, Potsdam-Golm, Germany
| | - D Magnus Eklund
- Department of Plant Ecology and Evolution, Evolutionary Biology Centre, Uppsala University, 75236, Uppsala, Sweden
| | - Claudia Köhler
- Department of Plant Biology, Swedish University of Agricultural Sciences and Linnean Center for Plant Biology, 75007, Uppsala, Sweden.
- Max Planck Institute of Molecular Plant Physiology, Potsdam, 14476, Potsdam-Golm, Germany.
| | - Lars Hennig
- Department of Plant Biology, Swedish University of Agricultural Sciences and Linnean Center for Plant Biology, 75007, Uppsala, Sweden
| |
Collapse
|
59
|
Zoroddu S, Marchesi I, Bagella L. PRC2: an epigenetic multiprotein complex with a key role in the development of rhabdomyosarcoma carcinogenesis. Clin Epigenetics 2021; 13:156. [PMID: 34372908 PMCID: PMC8351429 DOI: 10.1186/s13148-021-01147-w] [Citation(s) in RCA: 3] [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: 06/09/2021] [Accepted: 08/02/2021] [Indexed: 02/02/2023] Open
Abstract
Skeletal muscle formation represents a complex of highly organized and specialized systems that are still not fully understood. Epigenetic systems underline embryonic development, maintenance of stemness, and progression of differentiation. Polycomb group proteins play the role of gene silencing of stemness markers that regulate muscle differentiation. Enhancer of Zeste EZH2 is the catalytic subunit of the complex that is able to trimethylate lysine 27 of histone H3 and induce silencing of the involved genes. In embryonal Rhabdomyosarcoma and several other tumors, EZH2 is often deregulated and, in some cases, is associated with tumor malignancy. This review explores the molecular processes underlying the failure of muscle differentiation with a focus on the PRC2 complex. These considerations could open new studies aimed at the development of new cutting-edge therapeutic strategies in the onset of Rhabdomyosarcoma.
Collapse
Affiliation(s)
- Stefano Zoroddu
- Department of Biomedical Sciences, University of Sassari, Viale San Pietro 43/b, 07100, Sassari, Italy
| | - Irene Marchesi
- Department of Biomedical Sciences, University of Sassari, Viale San Pietro 43/b, 07100, Sassari, Italy
- Kitos Biotech Srls, Tramariglio, Alghero, SS, Italy
| | - Luigi Bagella
- Department of Biomedical Sciences, University of Sassari, Viale San Pietro 43/b, 07100, Sassari, Italy.
- Sbarro Institute for Cancer Research and Molecular Medicine, Center for Biotechnology, College of Science and Technology, Temple University, Philadelphia, PA, USA.
| |
Collapse
|
60
|
Brown K, Andrianakos H, Ingersoll S, Ren X. Single-molecule imaging of epigenetic complexes in living cells: insights from studies on Polycomb group proteins. Nucleic Acids Res 2021; 49:6621-6637. [PMID: 34009336 PMCID: PMC8266577 DOI: 10.1093/nar/gkab304] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 04/09/2021] [Accepted: 04/13/2021] [Indexed: 12/30/2022] Open
Abstract
Chromatin-associated factors must locate, bind to, and assemble on specific chromatin regions to execute chromatin-templated functions. These dynamic processes are essential for understanding how chromatin achieves regulation, but direct quantification in living mammalian cells remains challenging. Over the last few years, live-cell single-molecule tracking (SMT) has emerged as a new way to observe trajectories of individual chromatin-associated factors in living mammalian cells, providing new perspectives on chromatin-templated activities. Here, we discuss the relative merits of live-cell SMT techniques currently in use. We provide new insights into how Polycomb group (PcG) proteins, master regulators of development and cell differentiation, decipher genetic and epigenetic information to achieve binding stability and highlight that Polycomb condensates facilitate target-search efficiency. We provide perspectives on liquid-liquid phase separation in organizing Polycomb targets. We suggest that epigenetic complexes integrate genetic and epigenetic information for target binding and localization and achieve target-search efficiency through nuclear organization.
Collapse
Affiliation(s)
- Kyle Brown
- Department of Chemistry, University of Colorado Denver, Denver, CO 80217-3364, USA
| | | | - Steven Ingersoll
- Department of Chemistry, University of Colorado Denver, Denver, CO 80217-3364, USA
| | - Xiaojun Ren
- Department of Chemistry, University of Colorado Denver, Denver, CO 80217-3364, USA
| |
Collapse
|
61
|
Nguyen P, Pease NA, Kueh HY. Scalable control of developmental timetables by epigenetic switching networks. J R Soc Interface 2021; 18:20210109. [PMID: 34283940 DOI: 10.1098/rsif.2021.0109] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
During development, progenitor cells follow timetables for differentiation that span many cell generations. These developmental timetables are robustly encoded by the embryo, yet scalably adjustable by evolution, facilitating variation in organism size and form. Epigenetic switches, involving rate-limiting activation steps at regulatory gene loci, control gene activation timing in diverse contexts, and could profoundly impact the dynamics of gene regulatory networks controlling developmental lineage specification. Here, we develop a mathematical framework to model regulatory networks with genes controlled by epigenetic switches. Using this framework, we show that such epigenetic switching networks uphold developmental timetables that robustly span many cell generations, and enable the generation of differentiated cells in precisely defined numbers and fractions. Changes to epigenetic switching networks can readily alter the timing of developmental events within a timetable, or alter the overall speed at which timetables unfold, enabling scalable control over differentiated population sizes. With their robust, yet flexibly adjustable nature, epigenetic switching networks could represent central targets on which evolution acts to manufacture diversity in organism size and form.
Collapse
Affiliation(s)
- Phuc Nguyen
- Molecular Engineering and Sciences Program, University of Washington, Seattle, WA, USA
| | - Nicholas A Pease
- Molecular and Cellular Biology Program, University of Washington, Seattle, WA, USA
| | - Hao Yuan Kueh
- Department of Bioengineering, University of Washington, Seattle, WA, USA.,Institute of Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA, USA
| |
Collapse
|
62
|
Huang Y, Sicar S, Ramirez-Prado JS, Manza-Mianza D, Antunez-Sanchez J, Brik-Chaouche R, Rodriguez-Granados NY, An J, Bergounioux C, Mahfouz MM, Hirt H, Crespi M, Concia L, Barneche F, Amiard S, Probst AV, Gutierrez-Marcos J, Ariel F, Raynaud C, Latrasse D, Benhamed M. Polycomb-dependent differential chromatin compartmentalization determines gene coregulation in Arabidopsis. Genome Res 2021; 31:1230-1244. [PMID: 34083408 PMCID: PMC8256866 DOI: 10.1101/gr.273771.120] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Accepted: 05/20/2021] [Indexed: 11/24/2022]
Abstract
In animals, distant H3K27me3-marked Polycomb targets can establish physical interactions forming repressive chromatin hubs. In plants, growing evidence suggests that H3K27me3 acts directly or indirectly to regulate chromatin interactions, although how this histone modification modulates 3D chromatin architecture remains elusive. To decipher the impact of the dynamic deposition of H3K27me3 on the Arabidopsis thaliana nuclear interactome, we combined genetics, transcriptomics, and several 3D epigenomic approaches. By analyzing mutants defective for histone H3K27 methylation or demethylation, we uncovered the crucial role of this chromatin mark in short- and previously unnoticed long-range chromatin loop formation. We found that a reduction in H3K27me3 levels led to a decrease in the interactions within Polycomb-associated repressive domains. Regions with lower H3K27me3 levels in the H3K27 methyltransferase clf mutant established new interactions with regions marked with H3K9ac, a histone modification associated with active transcription, indicating that a reduction in H3K27me3 levels induces a global reconfiguration of chromatin architecture. Altogether, our results reveal that the 3D genome organization is tightly linked to reversible histone modifications that govern chromatin interactions. Consequently, nuclear organization dynamics shapes the transcriptional reprogramming during plant development and places H3K27me3 as a key feature in the coregulation of distant genes.
Collapse
Affiliation(s)
- Ying Huang
- Université Paris-Saclay, CNRS, INRAE, Univ Evry, Institute of Plant Sciences Paris-Saclay (IPS2), 91405, Orsay, France
| | - Sanchari Sicar
- Université Paris-Saclay, CNRS, INRAE, Univ Evry, Institute of Plant Sciences Paris-Saclay (IPS2), 91405, Orsay, France
| | - Juan S Ramirez-Prado
- Université Paris-Saclay, CNRS, INRAE, Univ Evry, Institute of Plant Sciences Paris-Saclay (IPS2), 91405, Orsay, France
| | - Deborah Manza-Mianza
- Université Paris-Saclay, CNRS, INRAE, Univ Evry, Institute of Plant Sciences Paris-Saclay (IPS2), 91405, Orsay, France
| | | | - Rim Brik-Chaouche
- Université Paris-Saclay, CNRS, INRAE, Univ Evry, Institute of Plant Sciences Paris-Saclay (IPS2), 91405, Orsay, France
| | - Natalia Y Rodriguez-Granados
- Université Paris-Saclay, CNRS, INRAE, Univ Evry, Institute of Plant Sciences Paris-Saclay (IPS2), 91405, Orsay, France
| | - Jing An
- Université Paris-Saclay, CNRS, INRAE, Univ Evry, Institute of Plant Sciences Paris-Saclay (IPS2), 91405, Orsay, France
| | - Catherine Bergounioux
- Université Paris-Saclay, CNRS, INRAE, Univ Evry, Institute of Plant Sciences Paris-Saclay (IPS2), 91405, Orsay, France
| | - Magdy M Mahfouz
- Division of Biological and Environmental Sciences and Engineering, King Abdullah University of Science and Technology, Thuwal 23955-6900, Kingdom of Saudi Arabia
| | - Heribert Hirt
- Université Paris-Saclay, CNRS, INRAE, Univ Evry, Institute of Plant Sciences Paris-Saclay (IPS2), 91405, Orsay, France
- Division of Biological and Environmental Sciences and Engineering, King Abdullah University of Science and Technology, Thuwal 23955-6900, Kingdom of Saudi Arabia
| | - Martin Crespi
- Université Paris-Saclay, CNRS, INRAE, Univ Evry, Institute of Plant Sciences Paris-Saclay (IPS2), 91405, Orsay, France
| | - Lorenzo Concia
- Université Paris-Saclay, CNRS, INRAE, Univ Evry, Institute of Plant Sciences Paris-Saclay (IPS2), 91405, Orsay, France
- Institut de Biologie de l'Ecole Normale Supérieure (IBENS), ENS, CNRS UMR8197, INSERM U1024, PSL Research University, 75005, Paris, France
| | - Fredy Barneche
- Institut de Biologie de l'Ecole Normale Supérieure (IBENS), ENS, CNRS UMR8197, INSERM U1024, PSL Research University, 75005, Paris, France
| | - Simon Amiard
- GReD, Université Clermont Auvergne, CNRS, INSERM, BP 38, 63001, Clermont-Ferrand, France
| | - Aline V Probst
- GReD, Université Clermont Auvergne, CNRS, INSERM, BP 38, 63001, Clermont-Ferrand, France
| | | | - Federico Ariel
- Instituto de Agrobiotecnología del Litoral, CONICET, Universidad Nacional del Litoral, 3000, Santa Fe, Argentina
| | - Cécile Raynaud
- Université Paris-Saclay, CNRS, INRAE, Univ Evry, Institute of Plant Sciences Paris-Saclay (IPS2), 91405, Orsay, France
| | - David Latrasse
- Université Paris-Saclay, CNRS, INRAE, Univ Evry, Institute of Plant Sciences Paris-Saclay (IPS2), 91405, Orsay, France
| | - Moussa Benhamed
- Université Paris-Saclay, CNRS, INRAE, Univ Evry, Institute of Plant Sciences Paris-Saclay (IPS2), 91405, Orsay, France
- Université de Paris, Institute of Plant Sciences Paris-Saclay (IPS2), F-75006 Paris, France
- Institut Universitaire de France (IUF)
| |
Collapse
|
63
|
Oss-Ronen L, Cohen I. Epigenetic regulation and signalling pathways in Merkel cell development. Exp Dermatol 2021; 30:1051-1064. [PMID: 34152646 DOI: 10.1111/exd.14415] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Revised: 06/15/2021] [Accepted: 06/17/2021] [Indexed: 12/20/2022]
Abstract
Merkel cells are specialized epithelial cells connected to afferent nerve endings responsible for light-touch sensations, formed at specific locations in touch-sensitive regions of the mammalian skin. Although Merkel cells are descendants of the epidermal lineage, little is known about the mechanisms responsible for the development of these unique mechanosensory cells. Recent studies have highlighted that the Polycomb group (PcG) of proteins play a significant role in spatiotemporal regulation of Merkel cell formation. In addition, several of the major signalling pathways involved in skin development have been shown to regulate Merkel cell development as well. Here, we summarize the current understandings of the role of developmental regulators in Merkel cell formation, including the interplay between the epigenetic machinery and key signalling pathways, and the lineage-specific transcription factors involved in the regulation of Merkel cell development.
Collapse
Affiliation(s)
- Liat Oss-Ronen
- The Shraga Segal Department of Microbiology, Immunology and Genetics, Faculty of Health Science, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Idan Cohen
- The Shraga Segal Department of Microbiology, Immunology and Genetics, Faculty of Health Science, Ben-Gurion University of the Negev, Beer Sheva, Israel
| |
Collapse
|
64
|
Rajpurkar AR, Mateo LJ, Murphy SE, Boettiger AN. Deep learning connects DNA traces to transcription to reveal predictive features beyond enhancer-promoter contact. Nat Commun 2021; 12:3423. [PMID: 34103507 PMCID: PMC8187657 DOI: 10.1038/s41467-021-23831-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Accepted: 05/19/2021] [Indexed: 11/27/2022] Open
Abstract
Chromatin architecture plays an important role in gene regulation. Recent advances in super-resolution microscopy have made it possible to measure chromatin 3D structure and transcription in thousands of single cells. However, leveraging these complex data sets with a computationally unbiased method has been challenging. Here, we present a deep learning-based approach to better understand to what degree chromatin structure relates to transcriptional state of individual cells. Furthermore, we explore methods to "unpack the black box" to determine in an unbiased manner which structural features of chromatin regulation are most important for gene expression state. We apply this approach to an Optical Reconstruction of Chromatin Architecture dataset of the Bithorax gene cluster in Drosophila and show it outperforms previous contact-focused methods in predicting expression state from 3D structure. We find the structural information is distributed across the domain, overlapping and extending beyond domains identified by prior genetic analyses. Individual enhancer-promoter interactions are a minor contributor to predictions of activity.
Collapse
Affiliation(s)
- Aparna R Rajpurkar
- Department of Genetics, Stanford University, Stanford, CA, USA
- Department of Developmental Biology, Stanford University, Stanford, CA, USA
| | - Leslie J Mateo
- Department of Developmental Biology, Stanford University, Stanford, CA, USA
| | - Sedona E Murphy
- Department of Genetics, Stanford University, Stanford, CA, USA
- Department of Developmental Biology, Stanford University, Stanford, CA, USA
| | | |
Collapse
|
65
|
Shen Q, Lin Y, Li Y, Wang G. Dynamics of H3K27me3 Modification on Plant Adaptation to Environmental Cues. PLANTS 2021; 10:plants10061165. [PMID: 34201297 PMCID: PMC8228231 DOI: 10.3390/plants10061165] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 05/30/2021] [Accepted: 06/01/2021] [Indexed: 12/13/2022]
Abstract
Given their sessile nature, plants have evolved sophisticated regulatory networks to confer developmental plasticity for adaptation to fluctuating environments. Epigenetic codes, like tri-methylation of histone H3 on Lys27 (H3K27me3), are evidenced to account for this evolutionary benefit. Polycomb repressive complex 2 (PRC2) and PRC1 implement and maintain the H3K27me3-mediated gene repression in most eukaryotic cells. Plants take advantage of this epigenetic machinery to reprogram gene expression in development and environmental adaption. Recent studies have uncovered a number of new players involved in the establishment, erasure, and regulation of H3K27me3 mark in plants, particularly highlighting new roles in plants’ responses to environmental cues. Here, we review current knowledge on PRC2-H3K27me3 dynamics occurring during plant growth and development, including its writers, erasers, and readers, as well as targeting mechanisms, and summarize the emerging roles of H3K27me3 mark in plant adaptation to environmental stresses.
Collapse
|
66
|
Xu J, Zhao X, Mao F, Basrur V, Ueberheide B, Chait BT, Allis CD, Taverna SD, Gao S, Wang W, Liu Y. A Polycomb repressive complex is required for RNAi-mediated heterochromatin formation and dynamic distribution of nuclear bodies. Nucleic Acids Res 2021; 49:5407-5425. [PMID: 33412588 PMCID: PMC8191774 DOI: 10.1093/nar/gkaa1262] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Revised: 12/02/2020] [Accepted: 01/04/2021] [Indexed: 01/17/2023] Open
Abstract
Polycomb group (PcG) proteins are widely utilized for transcriptional repression in eukaryotes. Here, we characterize, in the protist Tetrahymena thermophila, the EZL1 (E(z)-like 1) complex, with components conserved in metazoan Polycomb Repressive Complexes 1 and 2 (PRC1 and PRC2). The EZL1 complex is required for histone H3 K27 and K9 methylation, heterochromatin formation, transposable element control, and programmed genome rearrangement. The EZL1 complex interacts with EMA1, a helicase required for RNA interference (RNAi). This interaction is implicated in co-transcriptional recruitment of the EZL1 complex. Binding of H3K27 and H3K9 methylation by PDD1-another PcG protein interacting with the EZL1 complex-reinforces its chromatin association. The EZL1 complex is an integral part of Polycomb bodies, which exhibit dynamic distribution in Tetrahymena development: Their dispersion is driven by chromatin association, while their coalescence by PDD1, likely via phase separation. Our results provide a molecular mechanism connecting RNAi and Polycomb repression, which coordinately regulate nuclear bodies and reorganize the genome.
Collapse
Affiliation(s)
- Jing Xu
- School of Life Science, Shanxi University, Taiyuan, Shanxi 030006, China
| | - Xiaolu Zhao
- Department of Pathology, University of Michigan, Ann Arbor, MI 48109, USA
- Institute of Evolution & Marine Biodiversity, Ocean University of China, Qingdao 266003, China
| | - Fengbiao Mao
- Department of Pathology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Venkatesha Basrur
- Proteomics Resource Facility, Department of Pathology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Beatrix Ueberheide
- Laboratory of Mass Spectrometry and Gaseous Ion Chemistry, the Rockefeller University, New York, NY 10065, USA
| | - Brian T Chait
- Laboratory of Mass Spectrometry and Gaseous Ion Chemistry, the Rockefeller University, New York, NY 10065, USA
| | - C David Allis
- Laboratory of Chromatin Biology and Epigenetics, the Rockefeller University, New York, NY 10065, USA
| | - Sean D Taverna
- Department of Pharmacology and Molecular Sciences and the Center for Epigenetics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Shan Gao
- Institute of Evolution & Marine Biodiversity, Ocean University of China, Qingdao 266003, China
| | - Wei Wang
- School of Life Science, Shanxi University, Taiyuan, Shanxi 030006, China
| | - Yifan Liu
- Department of Pathology, University of Michigan, Ann Arbor, MI 48109, USA
| |
Collapse
|
67
|
Wu Y, Li M, Yang M. Post-Translational Modifications in Oocyte Maturation and Embryo Development. Front Cell Dev Biol 2021; 9:645318. [PMID: 34150752 PMCID: PMC8206635 DOI: 10.3389/fcell.2021.645318] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Accepted: 03/15/2021] [Indexed: 12/27/2022] Open
Abstract
Mammalian oocyte maturation and embryo development are unique biological processes regulated by various modifications. Since de novo mRNA transcription is absent during oocyte meiosis, protein-level regulation, especially post-translational modification (PTM), is crucial. It is known that PTM plays key roles in diverse cellular events such as DNA damage response, chromosome condensation, and cytoskeletal organization during oocyte maturation and embryo development. However, most previous reviews on PTM in oocytes and embryos have only focused on studies of Xenopus laevis or Caenorhabditis elegans eggs. In this review, we will discuss the latest discoveries regarding PTM in mammalian oocytes maturation and embryo development, focusing on phosphorylation, ubiquitination, SUMOylation and Poly(ADP-ribosyl)ation (PARylation). Phosphorylation functions in chromosome condensation and spindle alignment by regulating histone H3, mitogen-activated protein kinases, and some other pathways during mammalian oocyte maturation. Ubiquitination is a three-step enzymatic cascade that facilitates the degradation of proteins, and numerous E3 ubiquitin ligases are involved in modifying substrates and thus regulating oocyte maturation, oocyte-sperm binding, and early embryo development. Through the reversible addition and removal of SUMO (small ubiquitin-related modifier) on lysine residues, SUMOylation affects the cell cycle and DNA damage response in oocytes. As an emerging PTM, PARlation has been shown to not only participate in DNA damage repair, but also mediate asymmetric division of oocyte meiosis. Each of these PTMs and external environments is versatile and contributes to distinct phases during oocyte maturation and embryo development.
Collapse
Affiliation(s)
- Yu Wu
- Department of Obstetrics and Gynecology, Peking University Third Hospital, Beijing, China.,National Clinical Research Center for Obstetrics and Gynecology, Peking University Third Hospital, Beijing, China
| | - Mo Li
- Department of Obstetrics and Gynecology, Peking University Third Hospital, Beijing, China.,National Clinical Research Center for Obstetrics and Gynecology, Peking University Third Hospital, Beijing, China
| | - Mo Yang
- Medical Center for Human Reproduction, Beijing Chaoyang Hospital, Capital Medical University, Beijing, China
| |
Collapse
|
68
|
Weber CM, Hafner A, Kirkland JG, Braun SMG, Stanton BZ, Boettiger AN, Crabtree GR. mSWI/SNF promotes Polycomb repression both directly and through genome-wide redistribution. Nat Struct Mol Biol 2021; 28:501-511. [PMID: 34117481 PMCID: PMC8504423 DOI: 10.1038/s41594-021-00604-7] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Accepted: 05/10/2021] [Indexed: 02/05/2023]
Abstract
The mammalian SWI/SNF complex, or BAF complex, has a conserved and direct role in antagonizing Polycomb-mediated repression. Yet, BAF also promotes repression by Polycomb in stem cells and cancer. How BAF both antagonizes and promotes Polycomb-mediated repression remains unknown. Here, we utilize targeted protein degradation to dissect the BAF-Polycomb axis in mouse embryonic stem cells on short timescales. We report that rapid BAF depletion redistributes Polycomb repressive complexes PRC1 and PRC2 from highly occupied domains, like Hox clusters, to weakly occupied sites normally opposed by BAF. Polycomb redistribution from highly repressed domains results in their decompaction, gain of active epigenomic features and transcriptional derepression. Surprisingly, through dose-dependent degradation of PRC1 and PRC2, we identify a conventional role for BAF in Polycomb-mediated repression, in addition to global Polycomb redistribution. These findings provide new mechanistic insight into the highly dynamic state of the Polycomb-Trithorax axis.
Collapse
Affiliation(s)
- Christopher M. Weber
- Department of Pathology, Stanford University School of Medicine, Stanford, CA, USA.,Developmental Biology, Stanford University School of Medicine, Stanford, CA, USA
| | - Antonina Hafner
- Developmental Biology, Stanford University School of Medicine, Stanford, CA, USA
| | - Jacob G. Kirkland
- Department of Pathology, Stanford University School of Medicine, Stanford, CA, USA.,Developmental Biology, Stanford University School of Medicine, Stanford, CA, USA.,Cell Cycle and Cancer Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, USA
| | - Simon M. G. Braun
- Department of Pathology, Stanford University School of Medicine, Stanford, CA, USA.,Developmental Biology, Stanford University School of Medicine, Stanford, CA, USA.,University of Geneva, Department of Genetic Medicine, Geneva, Switzerland
| | - Benjamin Z. Stanton
- Nationwide Children’s Hospital, Center for Childhood Cancer and Blood Diseases, Columbus, OH, USA.,Department of Pediatrics, The Ohio State University College of Medicine, Columbus, OH, USA.,Department of Biological Chemistry and Pharmacology, The Ohio State University College of Medicine, Columbus, OH, USA
| | | | - Gerald R. Crabtree
- Department of Pathology, Stanford University School of Medicine, Stanford, CA, USA.,Developmental Biology, Stanford University School of Medicine, Stanford, CA, USA.,Howard Hughes Medical Institute, Chevy Chase, MD, USA.,Correspondence and requests for materials should be addressed to G.R.C.
| |
Collapse
|
69
|
Guo Y, Zhao S, Wang GG. Polycomb Gene Silencing Mechanisms: PRC2 Chromatin Targeting, H3K27me3 'Readout', and Phase Separation-Based Compaction. Trends Genet 2021; 37:547-565. [PMID: 33494958 PMCID: PMC8119337 DOI: 10.1016/j.tig.2020.12.006] [Citation(s) in RCA: 66] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Revised: 12/18/2020] [Accepted: 12/22/2020] [Indexed: 12/20/2022]
Abstract
Modulation of chromatin structure and/or modification by Polycomb repressive complexes (PRCs) provides an important means to partition the genome into functionally distinct subdomains and to regulate the activity of the underlying genes. Both the enzymatic activity of PRC2 and its chromatin recruitment, spreading, and eviction are exquisitely regulated via interactions with cofactors and DNA elements (such as unmethylated CpG islands), histones, RNA (nascent mRNA and long noncoding RNA), and R-loops. PRC2-catalyzed histone H3 lysine 27 trimethylation (H3K27me3) is recognized by distinct classes of effectors such as canonical PRC1 and BAH module-containing proteins (notably BAHCC1 in human). These effectors mediate gene silencing by different mechanisms including phase separation-related chromatin compaction and histone deacetylation. We discuss recent advances in understanding the structural architecture of PRC2, the regulation of its activity and chromatin recruitment, and the molecular mechanisms underlying Polycomb-mediated gene silencing. Because PRC deregulation is intimately associated with the development of diseases, a better appreciation of Polycomb-based (epi)genomic regulation will have far-reaching implications in biology and medicine.
Collapse
Affiliation(s)
- Yiran Guo
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC 27599, USA; Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Shuai Zhao
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC 27599, USA; Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC 27599, USA
| | - Gang Greg Wang
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC 27599, USA; Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC 27599, USA.
| |
Collapse
|
70
|
Feng Y, Liu X, Pauklin S. 3D chromatin architecture and epigenetic regulation in cancer stem cells. Protein Cell 2021; 12:440-454. [PMID: 33453053 PMCID: PMC8160035 DOI: 10.1007/s13238-020-00819-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Accepted: 12/05/2020] [Indexed: 12/29/2022] Open
Abstract
Dedifferentiation of cell identity to a progenitor-like or stem cell-like state with increased cellular plasticity is frequently observed in cancer formation. During this process, a subpopulation of cells in tumours acquires a stem cell-like state partially resembling to naturally occurring pluripotent stem cells that are temporarily present during early embryogenesis. Such characteristics allow these cancer stem cells (CSCs) to give rise to the whole tumour with its entire cellular heterogeneity and thereby support metastases formation while being resistant to current cancer therapeutics. Cancer development and progression are demarcated by transcriptional dysregulation. In this article, we explore the epigenetic mechanisms shaping gene expression during tumorigenesis and cancer stem cell formation, with an emphasis on 3D chromatin architecture. Comparing the pluripotent stem cell state and epigenetic reprogramming to dedifferentiation in cellular transformation provides intriguing insight to chromatin dynamics. We suggest that the 3D chromatin architecture could be used as a target for re-sensitizing cancer stem cells to therapeutics.
Collapse
Affiliation(s)
- Yuliang Feng
- Botnar Research Centre, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences Old Road, University of Oxford, Oxford, OX3 7LD, UK
| | - Xingguo Liu
- Guangzhou Regenerative Medicine and Health Guangdong Laboratory, CAS Key Laboratory of Regenerative Biology, Joint School of Life Sciences, Hefei Institute of Stem Cell and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences; Guangzhou Medical University, Guangzhou, 510530, China
- Guangdong Provincial Key Laboratory of Stem Cell and Regenerative Medicine, Institute for Stem Cell and Regeneration, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou, 510530, China
| | - Siim Pauklin
- Botnar Research Centre, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences Old Road, University of Oxford, Oxford, OX3 7LD, UK.
| |
Collapse
|
71
|
Woodworth MA, Ng KKH, Halpern AR, Pease NA, Nguyen PHB, Kueh HY, Vaughan JC. Multiplexed single-cell profiling of chromatin states at genomic loci by expansion microscopy. Nucleic Acids Res 2021; 49:e82. [PMID: 34048564 PMCID: PMC8373070 DOI: 10.1093/nar/gkab423] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2020] [Revised: 04/09/2021] [Accepted: 05/07/2021] [Indexed: 12/13/2022] Open
Abstract
Proper regulation of genome architecture and activity is essential for the development and function of multicellular organisms. Histone modifications, acting in combination, specify these activity states at individual genomic loci. However, the methods used to study these modifications often require either a large number of cells or are limited to targeting one histone mark at a time. Here, we developed a new method called Single Cell Evaluation of Post-TRanslational Epigenetic Encoding (SCEPTRE) that uses Expansion Microscopy (ExM) to visualize and quantify multiple histone modifications at non-repetitive genomic regions in single cells at a spatial resolution of ∼75 nm. Using SCEPTRE, we distinguished multiple histone modifications at a single housekeeping gene, quantified histone modification levels at multiple developmentally-regulated genes in individual cells, and evaluated the relationship between histone modifications and RNA polymerase II loading at individual loci. We find extensive variability in epigenetic states between individual gene loci hidden from current population-averaged measurements. These findings establish SCEPTRE as a new technique for multiplexed detection of combinatorial chromatin states at single genomic loci in single cells.
Collapse
Affiliation(s)
- Marcus A Woodworth
- Department of Chemistry, University of Washington, Seattle, WA 98195, USA
| | - Kenneth K H Ng
- Department of Bioengineering, University of Washington, Seattle, WA 98195, USA
| | - Aaron R Halpern
- Department of Chemistry, University of Washington, Seattle, WA 98195, USA
| | - Nicholas A Pease
- Department of Bioengineering, University of Washington, Seattle, WA 98195, USA
| | - Phuc H B Nguyen
- Department of Bioengineering, University of Washington, Seattle, WA 98195, USA
| | - Hao Yuan Kueh
- Department of Bioengineering, University of Washington, Seattle, WA 98195, USA
| | - Joshua C Vaughan
- Department of Chemistry, University of Washington, Seattle, WA 98195, USA.,Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195, USA
| |
Collapse
|
72
|
Ushiki A, Zhang Y, Xiong C, Zhao J, Georgakopoulos-Soares I, Kane L, Jamieson K, Bamshad MJ, Nickerson DA, Shen Y, Lettice LA, Silveira-Lucas EL, Petit F, Ahituv N. Deletion of CTCF sites in the SHH locus alters enhancer-promoter interactions and leads to acheiropodia. Nat Commun 2021; 12:2282. [PMID: 33863876 PMCID: PMC8052326 DOI: 10.1038/s41467-021-22470-z] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Accepted: 03/12/2021] [Indexed: 12/18/2022] Open
Abstract
Acheiropodia, congenital limb truncation, is associated with homozygous deletions in the LMBR1 gene around ZRS, an enhancer regulating SHH during limb development. How these deletions lead to this phenotype is unknown. Using whole-genome sequencing, we fine-mapped the acheiropodia-associated region to 12 kb and show that it does not function as an enhancer. CTCF and RAD21 ChIP-seq together with 4C-seq and DNA FISH identify three CTCF sites within the acheiropodia-deleted region that mediate the interaction between the ZRS and the SHH promoter. This interaction is substituted with other CTCF sites centromeric to the ZRS in the disease state. Mouse knockouts of the orthologous 12 kb sequence have no apparent abnormalities, showcasing the challenges in modelling CTCF alterations in animal models due to inherent motif differences between species. Our results show that alterations in CTCF motifs can lead to a Mendelian condition due to altered enhancer-promoter interactions.
Collapse
Affiliation(s)
- Aki Ushiki
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, CA, USA
- Institute for Human Genetics, University of California San Francisco, San Francisco, CA, USA
| | - Yichi Zhang
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, CA, USA
- Institute for Human Genetics, University of California San Francisco, San Francisco, CA, USA
- School of Pharmaceutical Sciences, Tsinghua University, Beijing, China
| | - Chenling Xiong
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, CA, USA
- Institute for Human Genetics, University of California San Francisco, San Francisco, CA, USA
| | - Jingjing Zhao
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, CA, USA
- Institute for Human Genetics, University of California San Francisco, San Francisco, CA, USA
| | - Ilias Georgakopoulos-Soares
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, CA, USA
- Institute for Human Genetics, University of California San Francisco, San Francisco, CA, USA
| | - Lauren Kane
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, UK
| | - Kirsty Jamieson
- Institute for Human Genetics, University of California San Francisco, San Francisco, CA, USA
| | - Michael J Bamshad
- Department of Pediatrics, University of Washington, Seattle, WA, USA
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
- Brotman-Baty Institute, Seattle, WA, USA
| | - Deborah A Nickerson
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
- Brotman-Baty Institute, Seattle, WA, USA
| | - Yin Shen
- Institute for Human Genetics, University of California San Francisco, San Francisco, CA, USA
- Department of Neurology, University of California San Francisco, San Francisco, CA, USA
| | - Laura A Lettice
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, UK
| | | | - Florence Petit
- CHU Lille, University of Lille, EA7364 RADEME, Lille, France
| | - Nadav Ahituv
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, CA, USA.
- Institute for Human Genetics, University of California San Francisco, San Francisco, CA, USA.
| |
Collapse
|
73
|
Sidwell T, Rothenberg EV. Epigenetic Dynamics in the Function of T-Lineage Regulatory Factor Bcl11b. Front Immunol 2021; 12:669498. [PMID: 33936112 PMCID: PMC8079813 DOI: 10.3389/fimmu.2021.669498] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Accepted: 03/23/2021] [Indexed: 11/18/2022] Open
Abstract
The transcription factor Bcl11b is critically required to support the development of diverse cell types, including T lymphocytes, type 2 innate lymphoid cells, neurons, craniofacial mesenchyme and keratinocytes. Although in T cell development its onset of expression is tightly linked to T-lymphoid lineage commitment, the Bcl11b protein in fact regulates substantially different sets of genes in different lymphocyte populations, playing strongly context-dependent roles. Somewhat unusually for lineage-defining transcription factors with site-specific DNA binding activity, much of the reported chromatin binding of Bcl11b appears to be indirect, or guided in large part by interactions with other transcription factors. We describe evidence suggesting that a further way in which Bcl11b exerts such distinct stage-dependent functions is by nucleating changes in regional suites of epigenetic modifications through recruitment of multiple families of chromatin-modifying enzyme complexes. Herein we explore what is - and what remains to be - understood of the roles of Bcl11b, its cofactors, and how it modifies the epigenetic state of the cell to enforce its diverse set of context-specific transcriptional and developmental programs.
Collapse
Affiliation(s)
- Tom Sidwell
- Division of Biology & Biological Engineering, California Institute of Technology, Pasadena, CA, United States
| | - Ellen V Rothenberg
- Division of Biology & Biological Engineering, California Institute of Technology, Pasadena, CA, United States
| |
Collapse
|
74
|
Pease NA, Nguyen PHB, Woodworth MA, Ng KKH, Irwin B, Vaughan JC, Kueh HY. Tunable, division-independent control of gene activation timing by a polycomb switch. Cell Rep 2021; 34:108888. [PMID: 33761349 PMCID: PMC8024876 DOI: 10.1016/j.celrep.2021.108888] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Revised: 12/17/2020] [Accepted: 03/01/2021] [Indexed: 01/09/2023] Open
Abstract
During development, progenitors often differentiate many cell generations after receiving signals. These delays must be robust yet tunable for precise population size control. Polycomb repressive mechanisms, involving histone H3 lysine-27 trimethylation (H3K27me3), restrain the expression of lineage-specifying genes in progenitors and may delay their activation and ensuing differentiation. Here, we elucidate an epigenetic switch controlling the T cell commitment gene Bcl11b that holds its locus in a heritable inactive state for multiple cell generations before activation. Integrating experiments and modeling, we identify a mechanism where H3K27me3 levels at Bcl11b, regulated by methyltransferase and demethylase activities, set the time delay at which the locus switches from a compacted, silent state to an extended, active state. This activation delay robustly spans many cell generations, is tunable by chromatin modifiers and transcription factors, and is independent of cell division. With their regulatory flexibility, such timed epigenetic switches may broadly control timing in development.
Collapse
Affiliation(s)
- Nicholas A Pease
- Department of Bioengineering, University of Washington, Seattle, WA 98195, USA; Molecular and Cellular Biology Program, University of Washington, Seattle, WA 98195, USA
| | - Phuc H B Nguyen
- Department of Bioengineering, University of Washington, Seattle, WA 98195, USA; Molecular Engineering and Sciences Institute, University of Washington, Seattle, WA 98195, USA
| | - Marcus A Woodworth
- Biological Physics, Structure and Design Program, University of Washington, Seattle, WA 98195, USA; Department of Chemistry, University of Washington, Seattle, WA 98195, USA
| | - Kenneth K H Ng
- Department of Bioengineering, University of Washington, Seattle, WA 98195, USA
| | - Blythe Irwin
- Department of Bioengineering, University of Washington, Seattle, WA 98195, USA
| | - Joshua C Vaughan
- Department of Chemistry, University of Washington, Seattle, WA 98195, USA; Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195, USA
| | - Hao Yuan Kueh
- Department of Bioengineering, University of Washington, Seattle, WA 98195, USA; Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA 98195, USA.
| |
Collapse
|
75
|
Piunti A, Shilatifard A. The roles of Polycomb repressive complexes in mammalian development and cancer. Nat Rev Mol Cell Biol 2021; 22:326-345. [PMID: 33723438 DOI: 10.1038/s41580-021-00341-1] [Citation(s) in RCA: 195] [Impact Index Per Article: 65.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/22/2021] [Indexed: 12/14/2022]
Abstract
More than 80 years ago, the first Polycomb-related phenotype was identified in Drosophila melanogaster. Later, a group of diverse genes collectively called Polycomb group (PcG) genes were identified based on common mutant phenotypes. PcG proteins, which are well-conserved in animals, were originally characterized as negative regulators of gene transcription during development and subsequently shown to function in various biological processes; their deregulation is associated with diverse phenotypes in development and in disease, especially cancer. PcG proteins function on chromatin and can form two distinct complexes with different enzymatic activities: Polycomb repressive complex 1 (PRC1) is a histone ubiquitin ligase and PRC2 is a histone methyltransferase. Recent studies have revealed the existence of various mutually exclusive PRC1 and PRC2 variants. In this Review, we discuss new concepts concerning the biochemical and molecular functions of these new PcG complex variants, and how their epigenetic activities are involved in mammalian development and cancer.
Collapse
Affiliation(s)
- Andrea Piunti
- Simpson Querrey Institute for Epigenetics, Northwestern University Feinberg School of Medicine, Chicago, IL, USA.,Department of Biochemistry and Molecular Genetics, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Ali Shilatifard
- Simpson Querrey Institute for Epigenetics, Northwestern University Feinberg School of Medicine, Chicago, IL, USA. .,Department of Biochemistry and Molecular Genetics, Northwestern University Feinberg School of Medicine, Chicago, IL, USA.
| |
Collapse
|
76
|
Zhang Q, Kuang G, He S, Liu S, Lu H, Li X, Zhou D, Huang Y. Chain-shattering Pt(IV)-backboned polymeric nanoplatform for efficient CRISPR/Cas9 gene editing to enhance synergistic cancer therapy. NANO RESEARCH 2021; 14:601-610. [DOI: 10.1007/s12274-020-3066-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 08/12/2020] [Accepted: 08/22/2020] [Indexed: 08/30/2023]
|
77
|
Huseyin MK, Klose RJ. Live-cell single particle tracking of PRC1 reveals a highly dynamic system with low target site occupancy. Nat Commun 2021; 12:887. [PMID: 33563969 PMCID: PMC7873255 DOI: 10.1038/s41467-021-21130-6] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2020] [Accepted: 01/13/2021] [Indexed: 01/04/2023] Open
Abstract
Polycomb repressive complex 1 (PRC1) is an essential chromatin-based repressor of gene transcription. How PRC1 engages with chromatin to identify its target genes and achieve gene repression remains poorly defined, representing a major hurdle to our understanding of Polycomb system function. Here, we use genome engineering and single particle tracking to dissect how PRC1 binds to chromatin in live mouse embryonic stem cells. We observe that PRC1 is highly dynamic, with only a small fraction stably interacting with chromatin. By integrating subunit-specific dynamics, chromatin binding, and abundance measurements, we discover that PRC1 exhibits low occupancy at target sites. Furthermore, we employ perturbation approaches to uncover how specific components of PRC1 define its kinetics and chromatin binding. Together, these discoveries provide a quantitative understanding of chromatin binding by PRC1 in live cells, suggesting that chromatin modification, as opposed to PRC1 complex occupancy, is central to gene repression.
Collapse
Affiliation(s)
- Miles K Huseyin
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
| | - Robert J Klose
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom.
| |
Collapse
|
78
|
Reevaluating the roles of histone-modifying enzymes and their associated chromatin modifications in transcriptional regulation. Nat Genet 2020; 52:1271-1281. [PMID: 33257899 DOI: 10.1038/s41588-020-00736-4] [Citation(s) in RCA: 183] [Impact Index Per Article: 45.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2020] [Accepted: 10/08/2020] [Indexed: 12/14/2022]
Abstract
Histone-modifying enzymes are implicated in the control of diverse DNA-templated processes including gene expression. Here, we outline historical and current thinking regarding the functions of histone modifications and their associated enzymes. One current viewpoint, based largely on correlative evidence, posits that histone modifications are instructive for transcriptional regulation and represent an epigenetic 'code'. Recent studies have challenged this model and suggest that histone marks previously associated with active genes do not directly cause transcriptional activation. Additionally, many histone-modifying proteins possess non-catalytic functions that overshadow their enzymatic activities. Given that much remains unknown regarding the functions of these proteins, the field should be cautious in interpreting loss-of-function phenotypes and must consider both cellular and developmental context. In this Perspective, we focus on recent progress relating to the catalytic and non-catalytic functions of the Trithorax-COMPASS complexes, Polycomb repressive complexes and Clr4/Suv39 histone-modifying machineries.
Collapse
|
79
|
Polycomb group-mediated histone H2A monoubiquitination in epigenome regulation and nuclear processes. Nat Commun 2020; 11:5947. [PMID: 33230107 PMCID: PMC7683540 DOI: 10.1038/s41467-020-19722-9] [Citation(s) in RCA: 73] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2019] [Accepted: 10/12/2020] [Indexed: 12/19/2022] Open
Abstract
Histone posttranslational modifications are key regulators of chromatin-associated processes including gene expression, DNA replication and DNA repair. Monoubiquitinated histone H2A, H2Aub (K118 in Drosophila or K119 in vertebrates) is catalyzed by the Polycomb group (PcG) repressive complex 1 (PRC1) and reversed by the PcG-repressive deubiquitinase (PR-DUB)/BAP1 complex. Here we critically assess the current knowledge regarding H2Aub deposition and removal, its crosstalk with PcG repressive complex 2 (PRC2)-mediated histone H3K27 methylation, and the recent attempts toward discovering its readers and solving its enigmatic functions. We also discuss mounting evidence of the involvement of H2A ubiquitination in human pathologies including cancer, while highlighting some knowledge gaps that remain to be addressed. Histone H2A monoubiquitination on lysine 119 in vertebrate and lysine 118 in Drosophila (H2Aub) is an epigenomic mark usually associated with gene repression by Polycomb group factors. Here the authors review the current knowledge on the deposition and removal of H2Aub, its function in transcription and other DNA-associated processes as well as its relevance to human disease.
Collapse
|
80
|
Geng Z, Gao Z. Mammalian PRC1 Complexes: Compositional Complexity and Diverse Molecular Mechanisms. Int J Mol Sci 2020; 21:E8594. [PMID: 33202645 PMCID: PMC7697839 DOI: 10.3390/ijms21228594] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Revised: 11/04/2020] [Accepted: 11/05/2020] [Indexed: 12/13/2022] Open
Abstract
Polycomb group (PcG) proteins function as vital epigenetic regulators in various biological processes, including pluripotency, development, and carcinogenesis. PcG proteins form multicomponent complexes, and two major types of protein complexes have been identified in mammals to date, Polycomb Repressive Complexes 1 and 2 (PRC1 and PRC2). The PRC1 complexes are composed in a hierarchical manner in which the catalytic core, RING1A/B, exclusively interacts with one of six Polycomb group RING finger (PCGF) proteins. This association with specific PCGF proteins allows for PRC1 to be subdivided into six distinct groups, each with their own unique modes of action arising from the distinct set of associated proteins. Historically, PRC1 was considered to be a transcription repressor that deposited monoubiquitylation of histone H2A at lysine 119 (H2AK119ub1) and compacted local chromatin. More recently, there is increasing evidence that demonstrates the transcription activation role of PRC1. Moreover, studies on the higher-order chromatin structure have revealed a new function for PRC1 in mediating long-range interactions. This provides a different perspective regarding both the transcription activation and repression characteristics of PRC1. This review summarizes new advancements regarding the composition of mammalian PRC1 and accompanying explanations of how diverse PRC1-associated proteins participate in distinct transcription regulation mechanisms.
Collapse
Affiliation(s)
- Zhuangzhuang Geng
- Departments of Biochemistry and Molecular Biology, Penn State College of Medicine, Hershey, PA 17033, USA;
| | - Zhonghua Gao
- Departments of Biochemistry and Molecular Biology, Penn State College of Medicine, Hershey, PA 17033, USA;
- Penn State Hershey Cancer Institute, Hershey, PA 17033, USA
- The Stem Cell and Regenerative Biology Program, Penn State College of Medicine, Hershey, PA 17033, USA
| |
Collapse
|
81
|
Seif E, Kang JJ, Sasseville C, Senkovich O, Kaltashov A, Boulier EL, Kapur I, Kim CA, Francis NJ. Phase separation by the polyhomeotic sterile alpha motif compartmentalizes Polycomb Group proteins and enhances their activity. Nat Commun 2020; 11:5609. [PMID: 33154383 PMCID: PMC7644731 DOI: 10.1038/s41467-020-19435-z] [Citation(s) in RCA: 65] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Accepted: 10/08/2020] [Indexed: 02/07/2023] Open
Abstract
Polycomb Group (PcG) proteins organize chromatin at multiple scales to regulate gene expression. A conserved Sterile Alpha Motif (SAM) in the Polycomb Repressive Complex 1 (PRC1) subunit Polyhomeotic (Ph) has been shown to play an important role in chromatin compaction and large-scale chromatin organization. Ph SAM forms helical head to tail polymers, and SAM-SAM interactions between chromatin-bound Ph/PRC1 are believed to compact chromatin and mediate long-range interactions. To understand the underlying mechanism, here we analyze the effects of Ph SAM on chromatin in vitro. We find that incubation of chromatin or DNA with a truncated Ph protein containing the SAM results in formation of concentrated, phase-separated condensates. Ph SAM-dependent condensates can recruit PRC1 from extracts and enhance PRC1 ubiquitin ligase activity towards histone H2A. We show that overexpression of Ph with an intact SAM increases ubiquitylated H2A in cells. Thus, SAM-induced phase separation, in the context of Ph, can mediate large-scale compaction of chromatin into biochemical compartments that facilitate histone modification.
Collapse
Affiliation(s)
- Elias Seif
- Institut de recherches cliniques de Montréal, 110 Avenue des Pins Ouest, Montréal, QC, H2W 1R7, Canada
| | - Jin Joo Kang
- Institut de recherches cliniques de Montréal, 110 Avenue des Pins Ouest, Montréal, QC, H2W 1R7, Canada
- Division of Experimental Medicine, McGill University, 1001 Decarie Boulevard, Montreal, QC, H4A 3J1, Canada
| | - Charles Sasseville
- Institut de recherches cliniques de Montréal, 110 Avenue des Pins Ouest, Montréal, QC, H2W 1R7, Canada
| | - Olga Senkovich
- Department of Biochemistry and Molecular Genetics, Midwestern University, 19555N. 59th St., Glendale, AZ, 85308, USA
| | - Alexander Kaltashov
- Institut de recherches cliniques de Montréal, 110 Avenue des Pins Ouest, Montréal, QC, H2W 1R7, Canada
| | - Elodie L Boulier
- Institut de recherches cliniques de Montréal, 110 Avenue des Pins Ouest, Montréal, QC, H2W 1R7, Canada
| | - Ibani Kapur
- Institut de recherches cliniques de Montréal, 110 Avenue des Pins Ouest, Montréal, QC, H2W 1R7, Canada
- Division of Experimental Medicine, McGill University, 1001 Decarie Boulevard, Montreal, QC, H4A 3J1, Canada
| | - Chongwoo A Kim
- Department of Biochemistry and Molecular Genetics, Midwestern University, 19555N. 59th St., Glendale, AZ, 85308, USA
| | - Nicole J Francis
- Institut de recherches cliniques de Montréal, 110 Avenue des Pins Ouest, Montréal, QC, H2W 1R7, Canada.
- Division of Experimental Medicine, McGill University, 1001 Decarie Boulevard, Montreal, QC, H4A 3J1, Canada.
- Département de biochimie et médecine moléculaire Université de Montréal, 2900 Boulevard Edouard-Montpetit, Montréal, QC, H3T 1J4, Canada.
| |
Collapse
|
82
|
Genome-wide identification and transcriptional modulation of histone variants and modification related genes in the low pH-exposed marine rotifer Brachionus koreanus. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY D-GENOMICS & PROTEOMICS 2020; 36:100748. [PMID: 33032078 DOI: 10.1016/j.cbd.2020.100748] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Revised: 09/05/2020] [Accepted: 09/18/2020] [Indexed: 11/22/2022]
Abstract
Histone modification is considered to be a major epigenetic control mechanism. These modifications (e.g. acetylation, phosphorylation, and methylation) may affect the interaction of histones with DNA and/or regulate DNA-based processes (e.g., recombination, repair, replication, and transcription) and chromatin remodeling complexes. Despite their significance in metazoan life and evolution, few studies have been conducted to identify genes undergoing epigenetic control modification in aquatic invertebrates. In this study, we identified whole core histones (70 total genes) and post-translational modification (PTM) histone genes (63 total genes) in the marine rotifer Brachionus koreanus through whole-genome analysis, and annotated them according to the human nomenclature. Notably, upon comparative analysis of cis-regulatory motif sequences, we found that B. koreanus core histone protein structures were similar to those of mammals. Furthermore, to examine the effect of parental low pH stress on the offspring's epigenetic regulation, we investigated the expression of PTM genes in two generations of B. koreanus exposed to low pH conditions. Given that the B. koreanus genome does not possess DNA methyltransferase 1 and 3 genes, we concluded that histone genes could be involved as an important epigenetic mechanism in B. koreanus. Therefore, the histone-associated genes identified in this study could be useful for ecotoxicological studies and facilitate the application of chromatin immunoprecipitation sequencing using high-throughput DNA sequencing based on the genome-wide identification of transcription factor binding sites in rotifers.
Collapse
|
83
|
Kent S, Brown K, Yang CH, Alsaihati N, Tian C, Wang H, Ren X. Phase-Separated Transcriptional Condensates Accelerate Target-Search Process Revealed by Live-Cell Single-Molecule Imaging. Cell Rep 2020; 33:108248. [PMID: 33053359 PMCID: PMC7593837 DOI: 10.1016/j.celrep.2020.108248] [Citation(s) in RCA: 76] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Revised: 08/07/2020] [Accepted: 09/17/2020] [Indexed: 12/11/2022] Open
Abstract
Compartmentalization by liquid-liquid phase separation is implicated in transcription. It remains unclear whether and how transcriptional condensates accelerate the search of transcriptional regulatory factors for their target sites. Furthermore, the molecular mechanisms by which regulatory factors nucleate on chromatin to assemble transcriptional condensates remain incompletely understood. The CBX-PRC1 complexes compartmentalize key developmental regulators for repression through phase-separated condensates driven by the chromobox 2 (CBX2) protein. Here, by using live-cell single-molecule imaging, we show that CBX2 nucleates on chromatin independently of H3K27me3 and CBX-PRC1. The interactions between CBX2 and DNA are essential for nucleating CBX-PRC1 on chromatin to assemble condensates. The assembled condensates shorten 3D diffusion time and reduce trials for finding specific sites through revisiting the same or adjacent sites repetitively, thereby accelerating CBX2 in searching for target sites. Overall, our data suggest a generic mechanism by which transcriptional regulatory factors nucleate to assemble condensates that accelerate their target-search process. Kent et al. demonstrate that CBX2 phase separates to assemble Polycomb condensates on chromatin through CBX2 interactions with DNA rather than H3K27me3. The assembled condensates accelerate the search of CBX2 for its cognate binding sites by revisiting the same or adjacent sites repetitively, thereby enhancing the genomic occupancy of CBX2.
Collapse
Affiliation(s)
- Samantha Kent
- Department of Chemistry, University of Colorado Denver, Denver, CO 80217-3364, USA
| | - Kyle Brown
- Department of Chemistry, University of Colorado Denver, Denver, CO 80217-3364, USA
| | - Chou-Hsun Yang
- Department of Chemistry, University of Colorado Denver, Denver, CO 80217-3364, USA
| | - Njood Alsaihati
- Department of Chemistry, University of Colorado Denver, Denver, CO 80217-3364, USA
| | - Christina Tian
- Department of Chemistry, University of Colorado Denver, Denver, CO 80217-3364, USA
| | - Haobin Wang
- Department of Chemistry, University of Colorado Denver, Denver, CO 80217-3364, USA
| | - Xiaojun Ren
- Department of Chemistry, University of Colorado Denver, Denver, CO 80217-3364, USA.
| |
Collapse
|
84
|
Gonçalves CS, Le Boiteux E, Arnaud P, Costa BM. HOX gene cluster (de)regulation in brain: from neurodevelopment to malignant glial tumours. Cell Mol Life Sci 2020; 77:3797-3821. [PMID: 32239260 PMCID: PMC11105007 DOI: 10.1007/s00018-020-03508-9] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Revised: 03/10/2020] [Accepted: 03/17/2020] [Indexed: 12/19/2022]
Abstract
HOX genes encode a family of evolutionarily conserved homeodomain transcription factors that are crucial both during development and adult life. In humans, 39 HOX genes are arranged in four clusters (HOXA, B, C, and D) in chromosomes 7, 17, 12, and 2, respectively. During embryonic development, particular epigenetic states accompany their expression along the anterior-posterior body axis. This tightly regulated temporal-spatial expression pattern reflects their relative chromosomal localization, and is critical for normal embryonic brain development when HOX genes are mainly expressed in the hindbrain and mostly absent in the forebrain region. Epigenetic marks, mostly polycomb-associated, are dynamically regulated at HOX loci and regulatory regions to ensure the finely tuned HOX activation and repression, highlighting a crucial epigenetic plasticity necessary for homeostatic development. HOX genes are essentially absent in healthy adult brain, whereas they are detected in malignant brain tumours, namely gliomas, where HOX genes display critical roles by regulating several hallmarks of cancer. Here, we review the major mechanisms involved in HOX genes (de)regulation in the brain, from embryonic to adult stages, in physiological and oncologic conditions. We focus particularly on the emerging causes of HOX gene deregulation in glioma, as well as on their functional and clinical implications.
Collapse
Affiliation(s)
- Céline S Gonçalves
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Campus de Gualtar, 4710-057, Braga, Portugal
- ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - Elisa Le Boiteux
- Université Clermont Auvergne, CNRS, INSERM-iGReD, Clermont-Ferrand, France
| | - Philippe Arnaud
- Université Clermont Auvergne, CNRS, INSERM-iGReD, Clermont-Ferrand, France
| | - Bruno M Costa
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Campus de Gualtar, 4710-057, Braga, Portugal.
- ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal.
| |
Collapse
|
85
|
McBride MJ, Mashtalir N, Winter EB, Dao HT, Filipovski M, D'Avino AR, Seo HS, Umbreit NT, St Pierre R, Valencia AM, Qian K, Zullow HJ, Jaffe JD, Dhe-Paganon S, Muir TW, Kadoch C. The nucleosome acidic patch and H2A ubiquitination underlie mSWI/SNF recruitment in synovial sarcoma. Nat Struct Mol Biol 2020; 27:836-845. [PMID: 32747783 PMCID: PMC7714695 DOI: 10.1038/s41594-020-0466-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Accepted: 06/11/2020] [Indexed: 12/18/2022]
Abstract
Interactions between chromatin-associated proteins and the histone landscape play major roles in dictating genome topology and gene expression. Cancer-specific fusion oncoproteins, which display unique chromatin localization patterns, often lack classical DNA-binding domains, presenting challenges in identifying mechanisms governing their site-specific chromatin targeting and function. Here we identify a minimal region of the human SS18-SSX fusion oncoprotein (the hallmark driver of synovial sarcoma) that mediates a direct interaction between the mSWI/SNF complex and the nucleosome acidic patch. This binding results in altered mSWI/SNF composition and nucleosome engagement, driving cancer-specific mSWI/SNF complex targeting and gene expression. Furthermore, the C-terminal region of SSX confers preferential affinity to repressed, H2AK119Ub-marked nucleosomes, underlying the selective targeting to polycomb-marked genomic regions and synovial sarcoma-specific dependency on PRC1 function. Together, our results describe a functional interplay between a key nucleosome binding hub and a histone modification that underlies the disease-specific recruitment of a major chromatin remodeling complex.
Collapse
Affiliation(s)
- Matthew J McBride
- Department of Pediatric Oncology, Dana-Farber Cancer Institute and Harvard Medical School, Boston, MA, USA
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Program in Chemical Biology, Harvard University, Cambridge, MA, USA
| | - Nazar Mashtalir
- Department of Pediatric Oncology, Dana-Farber Cancer Institute and Harvard Medical School, Boston, MA, USA
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Evan B Winter
- Department of Pediatric Oncology, Dana-Farber Cancer Institute and Harvard Medical School, Boston, MA, USA
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Hai T Dao
- Department of Chemistry, Princeton University, Princeton, NJ, USA
| | - Martin Filipovski
- Department of Pediatric Oncology, Dana-Farber Cancer Institute and Harvard Medical School, Boston, MA, USA
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Andrew R D'Avino
- Department of Pediatric Oncology, Dana-Farber Cancer Institute and Harvard Medical School, Boston, MA, USA
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Hyuk-Soo Seo
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA, USA
| | - Neil T Umbreit
- Department of Pediatric Oncology, Dana-Farber Cancer Institute and Harvard Medical School, Boston, MA, USA
- Department of Cell Biology, Harvard Medical School, Boston, MA, USA
| | - Roodolph St Pierre
- Department of Pediatric Oncology, Dana-Farber Cancer Institute and Harvard Medical School, Boston, MA, USA
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Program in Chemical Biology, Harvard University, Cambridge, MA, USA
| | - Alfredo M Valencia
- Department of Pediatric Oncology, Dana-Farber Cancer Institute and Harvard Medical School, Boston, MA, USA
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Program in Chemical Biology, Harvard University, Cambridge, MA, USA
| | - Kristin Qian
- Department of Pediatric Oncology, Dana-Farber Cancer Institute and Harvard Medical School, Boston, MA, USA
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Biological and Biomedical Sciences Program, Harvard Medical School, Boston, MA, USA
| | - Hayley J Zullow
- Department of Pediatric Oncology, Dana-Farber Cancer Institute and Harvard Medical School, Boston, MA, USA
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Biological and Biomedical Sciences Program, Harvard Medical School, Boston, MA, USA
| | - Jacob D Jaffe
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Sirano Dhe-Paganon
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA, USA
| | - Tom W Muir
- Department of Chemistry, Princeton University, Princeton, NJ, USA
| | - Cigall Kadoch
- Department of Pediatric Oncology, Dana-Farber Cancer Institute and Harvard Medical School, Boston, MA, USA.
- Broad Institute of MIT and Harvard, Cambridge, MA, USA.
| |
Collapse
|
86
|
The genetic basis for PRC1 complex diversity emerged early in animal evolution. Proc Natl Acad Sci U S A 2020; 117:22880-22889. [PMID: 32868440 DOI: 10.1073/pnas.2005136117] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Polycomb group proteins are essential regulators of developmental processes across animals. Despite their importance, studies on Polycomb are often restricted to classical model systems and, as such, little is known about the evolution of these important chromatin regulators. Here we focus on Polycomb Repressive Complex 1 (PRC1) and trace the evolution of core components of canonical and non-canonical PRC1 complexes in animals. Previous work suggested that a major expansion in the number of PRC1 complexes occurred in the vertebrate lineage. We show that the expansion of the Polycomb Group RING Finger (PCGF) protein family, an essential step for the establishment of the large diversity of PRC1 complexes found in vertebrates, predates the bilaterian-cnidarian ancestor. This means that the genetic repertoire necessary to form all major vertebrate PRC1 complexes emerged early in animal evolution, over 550 million years ago. We further show that PCGF5, a gene conserved in cnidarians and vertebrates but lost in all other studied groups, is expressed in the nervous system in the sea anemone Nematostella vectensis, similar to its mammalian counterpart. Together this work provides a framework for understanding the evolution of PRC1 complex diversity and it establishes Nematostella as a promising model system in which the functional ramifications of this diversification can be further explored.
Collapse
|
87
|
Gentile C, Kmita M. Polycomb Repressive Complexes in Hox Gene Regulation: Silencing and Beyond: The Functional Dynamics of Polycomb Repressive Complexes in Hox Gene Regulation. Bioessays 2020; 42:e1900249. [PMID: 32743818 DOI: 10.1002/bies.201900249] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Revised: 06/17/2020] [Indexed: 11/10/2022]
Abstract
The coordinated expression of the Hox gene family encoding transcription factors is critical for proper embryonic development and patterning. Major efforts have thus been dedicated to understanding mechanisms controlling Hox expression. In addition to the temporal and spatial sequential activation of Hox genes, proper embryonic development requires that Hox genes get differentially silenced in a cell-type specific manner as development proceeds. Factors contributing to Hox silencing include the polycomb repressive complexes (PRCs), which control gene expression through epigenetic modifications. This review focuses on PRC-dependent regulation of the Hox genes and is aimed at integrating the growing complexity of PRC functional properties in the context of Hox regulation. In particular, mechanisms underlying PRC binding dynamics as well as a series of studies that have revealed the impact of PRC on the 3D organization of the genome is discussed, which has a significant role on Hox regulation during development.
Collapse
Affiliation(s)
- Claudia Gentile
- Genetics and Development Research Unit, Institut de Recherches Cliniques de Montréal, Montréal, Québec, H2W 1R7, Canada.,Department of Experimental Medicine, McGill University, Montreal, Quebec, H4A 3J1, Canada.,Dana-Farber Cancer Institute and Harvard Medical School, Boston, MA, 02215, USA
| | - Marie Kmita
- Genetics and Development Research Unit, Institut de Recherches Cliniques de Montréal, Montréal, Québec, H2W 1R7, Canada.,Department of Experimental Medicine, McGill University, Montreal, Quebec, H4A 3J1, Canada.,Département de Médecine, Université de Montréal, Montréal, Quebec, H3C 3J7, Canada
| |
Collapse
|
88
|
Linhares BM, Grembecka J, Cierpicki T. Targeting epigenetic protein-protein interactions with small-molecule inhibitors. Future Med Chem 2020; 12:1305-1326. [PMID: 32551894 PMCID: PMC7421387 DOI: 10.4155/fmc-2020-0082] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2020] [Accepted: 05/01/2020] [Indexed: 02/07/2023] Open
Abstract
Epigenetic protein-protein interactions (PPIs) play essential roles in regulating gene expression, and their dysregulations have been implicated in many diseases. These PPIs are comprised of reader domains recognizing post-translational modifications on histone proteins, and of scaffolding proteins that maintain integrities of epigenetic complexes. Targeting PPIs have become focuses for development of small-molecule inhibitors and anticancer therapeutics. Here we summarize efforts to develop small-molecule inhibitors targeting common epigenetic PPI domains. Potent small molecules have been reported for many domains, yet small domains that recognize methylated lysine side chains on histones are challenging in inhibitor development. We posit that the development of potent inhibitors for difficult-to-prosecute epigenetic PPIs may be achieved by interdisciplinary approaches and extensive explorations of chemical space.
Collapse
Affiliation(s)
- Brian M Linhares
- Biophysics Program, University of Michigan, Ann Arbor, MI 48109, USA
- Department of Molecular, Cellular & Developmental Biology, Yale University, New Haven, CT 06511, USA
| | - Jolanta Grembecka
- Department of Pathology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Tomasz Cierpicki
- Biophysics Program, University of Michigan, Ann Arbor, MI 48109, USA
- Department of Pathology, University of Michigan, Ann Arbor, MI 48109, USA
| |
Collapse
|
89
|
Kralemann LEM, Liu S, Trejo-Arellano MS, Muñoz-Viana R, Köhler C, Hennig L. Removal of H2Aub1 by ubiquitin-specific proteases 12 and 13 is required for stable Polycomb-mediated gene repression in Arabidopsis. Genome Biol 2020; 21:144. [PMID: 32546254 PMCID: PMC7296913 DOI: 10.1186/s13059-020-02062-8] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Accepted: 05/27/2020] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Stable gene repression is essential for normal growth and development. Polycomb repressive complexes 1 and 2 (PRC1&2) are involved in this process by establishing monoubiquitination of histone 2A (H2Aub1) and subsequent trimethylation of lysine 27 of histone 3 (H3K27me3). Previous work proposed that H2Aub1 removal by the ubiquitin-specific proteases 12 and 13 (UBP12 and UBP13) is part of the repressive PRC1&2 system, but its functional role remains elusive. RESULTS We show that UBP12 and UBP13 work together with PRC1, PRC2, and EMF1 to repress genes involved in stimulus response. We find that PRC1-mediated H2Aub1 is associated with gene responsiveness, and its repressive function requires PRC2 recruitment. We further show that the requirement of PRC1 for PRC2 recruitment depends on the initial expression status of genes. Lastly, we demonstrate that removal of H2Aub1 by UBP12/13 prevents loss of H3K27me3, consistent with our finding that the H3K27me3 demethylase REF6 is positively associated with H2Aub1. CONCLUSIONS Our data allow us to propose a model in which deposition of H2Aub1 permits genes to switch between repression and activation by H3K27me3 deposition and removal. Removal of H2Aub1 by UBP12/13 is required to achieve stable PRC2-mediated repression.
Collapse
Affiliation(s)
- Lejon E. M. Kralemann
- Department of Plant Biology, Uppsala BioCenter, Swedish University of Agricultural Sciences and Linnean Centre for Plant Biology, SE-75007 Uppsala, Sweden
| | - Shujing Liu
- Department of Plant Biology, Uppsala BioCenter, Swedish University of Agricultural Sciences and Linnean Centre for Plant Biology, SE-75007 Uppsala, Sweden
| | - Minerva S. Trejo-Arellano
- Department of Plant Biology, Uppsala BioCenter, Swedish University of Agricultural Sciences and Linnean Centre for Plant Biology, SE-75007 Uppsala, Sweden
| | - Rafael Muñoz-Viana
- Instituto de Neurociencias, Universidad Miguel Hernández-Consejo Superior de Investigaciones Científicas, 03550 Sant Joan d’Alacant, Spain
| | - Claudia Köhler
- Department of Plant Biology, Uppsala BioCenter, Swedish University of Agricultural Sciences and Linnean Centre for Plant Biology, SE-75007 Uppsala, Sweden
| | - Lars Hennig
- Department of Plant Biology, Uppsala BioCenter, Swedish University of Agricultural Sciences and Linnean Centre for Plant Biology, SE-75007 Uppsala, Sweden
| |
Collapse
|
90
|
Boyle S, Flyamer IM, Williamson I, Sengupta D, Bickmore WA, Illingworth RS. A central role for canonical PRC1 in shaping the 3D nuclear landscape. Genes Dev 2020; 34:931-949. [PMID: 32439634 PMCID: PMC7328521 DOI: 10.1101/gad.336487.120] [Citation(s) in RCA: 83] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Accepted: 04/13/2020] [Indexed: 02/04/2023]
Abstract
In this study from Boyle et al., the authors investigated the role of Polycomb-repressive complex 1 (PRC1) in shaping 3D genome organization in mouse embryonic stem cells. Using a combination of imaging and Hi-C analyses they show that PRC1-mediated long-range interactions are independent of CTCF and can bridge sites at a megabase scale, thus providing novel insights into the function of PRC1. Polycomb group (PcG) proteins silence gene expression by chemically and physically modifying chromatin. A subset of PcG target loci are compacted and cluster in the nucleus; a conformation that is thought to contribute to gene silencing. However, how these interactions influence gross nuclear organization and their relationship with transcription remains poorly understood. Here we examine the role of Polycomb-repressive complex 1 (PRC1) in shaping 3D genome organization in mouse embryonic stem cells (mESCs). Using a combination of imaging and Hi-C analyses, we show that PRC1-mediated long-range interactions are independent of CTCF and can bridge sites at a megabase scale. Impairment of PRC1 enzymatic activity does not directly disrupt these interactions. We demonstrate that PcG targets coalesce in vivo, and that developmentally induced expression of one of the target loci disrupts this spatial arrangement. Finally, we show that transcriptional activation and the loss of PRC1-mediated interactions are separable events. These findings provide important insights into the function of PRC1, while highlighting the complexity of this regulatory system.
Collapse
Affiliation(s)
- Shelagh Boyle
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XU, United Kingdom
| | - Ilya M Flyamer
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XU, United Kingdom
| | - Iain Williamson
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XU, United Kingdom
| | - Dipta Sengupta
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XU, United Kingdom
| | - Wendy A Bickmore
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XU, United Kingdom
| | - Robert S Illingworth
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XU, United Kingdom
| |
Collapse
|
91
|
Pachano T, Crispatzu G, Rada-Iglesias A. Polycomb proteins as organizers of 3D genome architecture in embryonic stem cells. Brief Funct Genomics 2020; 18:358-366. [PMID: 31673701 DOI: 10.1093/bfgp/elz022] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2019] [Revised: 08/14/2019] [Accepted: 08/22/2019] [Indexed: 12/29/2022] Open
Abstract
Polycomb group proteins (PcGs) control the epigenetic and transcriptional state of developmental genes and regulatory elements during mammalian embryogenesis. Moreover, PcGs can also contribute to 3D genome organization, adding an additional layer of complexity to their regulatory functions. Understanding the mechanistic basis and the dynamics of PcG-dependent chromatin structures will help us untangle the full complexity of PcG function during development. Since most studies concerning the 3D organization of PcG-bound chromatin in mammals have been performed in embryonic stem cells (ESCs), here we will focus on this cell type characterized by its unique self-renewal and pluripotency properties. More specifically, we will highlight recent findings and discuss open questions regarding how PcG-dependent changes in 3D chromatin architecture control gene expression, cellular identity and differentiation potential in ESCs. We believe that this can serve to illustrate the diverse regulatory mechanisms by which PcG proteins control the proper execution of gene expression programs during mammalian embryogenesis.
Collapse
Affiliation(s)
- Tomas Pachano
- Center for Molecular Medicine Cologne (CMMC), University of Cologne, Germany
| | - Giuliano Crispatzu
- Center for Molecular Medicine Cologne (CMMC), University of Cologne, Germany.,Department II of Internal Medicine, University Hospital Cologne, Germany
| | - Alvaro Rada-Iglesias
- Center for Molecular Medicine Cologne (CMMC), University of Cologne, Germany.,Cluster of Excellence Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Germany.,Institute of Biomedicine and Biotechnology of Cantabria (IBBTEC), University of Cantabria, Spain
| |
Collapse
|
92
|
Abstract
Methylation of histone H3 lysine 27 (H3K27) is widely recognized as a transcriptionally repressive chromatin modification but the mechanism of repression remains unclear. We devised and implemented a forward genetic scheme to identify factors required for H3K27 methylation-mediated silencing in the filamentous fungus Neurospora crassa and identified a bromo-adjacent homology (BAH)-plant homeodomain (PHD)-containing protein, EPR-1 (effector of polycomb repression 1; NCU07505). EPR-1 associates with H3K27-methylated chromatin, and loss of EPR-1 de-represses H3K27-methylated genes without loss of H3K27 methylation. EPR-1 is not fungal-specific; orthologs of EPR-1 are present in a diverse array of eukaryotic lineages, suggesting an ancestral EPR-1 was a component of a primitive Polycomb repression pathway.
Collapse
|
93
|
Brackley CA. Polymer compaction and bridging-induced clustering of protein-inspired patchy particles. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:314002. [PMID: 32175915 DOI: 10.1088/1361-648x/ab7f6c] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Accepted: 03/12/2020] [Indexed: 06/10/2023]
Abstract
There are many proteins or protein complexes which have multiple DNA binding domains. This allows them to bind to multiple points on a DNA molecule (or chromatin fibre) at the same time. There are also many proteins which have been found to be able to compact DNAin vitro, and many others have been observed in foci or puncta when fluorescently labelled and imagedin vivo. In this work we study, using coarse-grained Langevin dynamics simulations, the compaction of polymers by simple model proteins and a phenomenon known as the 'bridging-induced attraction'. The latter is a mechanism observed in previous simulations [Brackleyet al2013Proc. Natl Acad. Sci. USA110E3605], where proteins modelled as spheres form clusters via their multivalent interactions with a polymer, even in the absence of any explicit protein-protein attractive interactions. Here we extend this concept to consider more detailed model proteins, represented as simple 'patchy particles' interacting with a semi-flexible bead-and-spring polymer. We find that both the compacting ability and the effect of the bridging-induced attraction depend on the valence of the model proteins. These effects also depend on the shape of the protein, which determines its ability to form bridges.
Collapse
Affiliation(s)
- C A Brackley
- SUPA, School of Physics & Astronomy, University of Edinburgh, Peter Guthrie Tait Road, Edinburgh, EH9 3FD, United Kingdom
| |
Collapse
|
94
|
Cohen I, Bar C, Ezhkova E. Activity of PRC1 and Histone H2AK119 Monoubiquitination: Revising Popular Misconceptions. Bioessays 2020; 42:e1900192. [PMID: 32196702 PMCID: PMC7585675 DOI: 10.1002/bies.201900192] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Revised: 02/12/2020] [Indexed: 12/21/2022]
Abstract
Polycomb group proteins are evolutionary conserved chromatin-modifying complexes, essential for the regulation of developmental and cell-identity genes. Polycomb-mediated transcriptional regulation is provided by two multi-protein complexes known as Polycomb repressive complex 1 (PRC1) and 2 (PRC2). Recent studies positioned PRC1 as a foremost executer of Polycomb-mediated transcriptional control. Mammalian PRC1 complexes can form multiple sub-complexes that vary in their core and accessory subunit composition, leading to fascinating and diverse transcriptional regulatory mechanisms employed by PRC1 complexes. These mechanisms include PRC1-catalytic activity toward monoubiquitination of histone H2AK119, a well-established hallmark of PRC1 complexes, whose importance has been long debated. In this review, the central roles that PRC1-catalytic activity plays in transcriptional repression are emphasized and the recent evidence supporting a role for PRC1 complexes in gene activation is discussed.
Collapse
Affiliation(s)
- Idan Cohen
- The Shraga Segal Department of Microbiology, Immunology and Genetics; Faculty of Health Science; Ben-Gurion University of the Negev; Beer Sheva 84105; Israel
- These authors contributed equally to this work
| | - Carmit Bar
- Black Family Stem Cell Institute, Department of Cell, Developmental, and Regenerative Biology; Icahn School of Medicine at Mount Sinai; 1 Gustave L. Levy Place, New York, NY 10029; USA
- These authors contributed equally to this work
| | - Elena Ezhkova
- The Shraga Segal Department of Microbiology, Immunology and Genetics; Faculty of Health Science; Ben-Gurion University of the Negev; Beer Sheva 84105; Israel
| |
Collapse
|
95
|
Yianni V, Sharpe PT. Epigenetic mechanisms driving lineage commitment in mesenchymal stem cells. Bone 2020; 134:115309. [PMID: 32145460 DOI: 10.1016/j.bone.2020.115309] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Revised: 03/02/2020] [Accepted: 03/02/2020] [Indexed: 12/15/2022]
Abstract
The increasing application of approaches that allow tracing of individual cells over time, together with transcriptomic and epigenomic analyses is changing the way resident stromal stem cells (mesenchymal stem cells) are viewed. Rather than being a defined, homogeneous cell population as described following in vitro expansion, in vivo, these cells are highly programmed according to their resident tissue location. This programming is evidenced by different epigenetic landscapes and gene transcription signatures in cells before any in vitro expansion. This has potentially profound implications for the heterotypic use of these cells in therapeutic tissue engineering applications.
Collapse
Affiliation(s)
- Val Yianni
- Centre for Craniofacial & Regenerative Biology, Faculty of Dentistry, Oral & Craniofacial Sciences, King's College London, United Kingdom of Great Britain and Northern Ireland
| | - Paul T Sharpe
- Centre for Craniofacial & Regenerative Biology, Faculty of Dentistry, Oral & Craniofacial Sciences, King's College London, United Kingdom of Great Britain and Northern Ireland.
| |
Collapse
|
96
|
Zepeda-Martinez JA, Pribitzer C, Wang J, Bsteh D, Golumbeanu S, Zhao Q, Burkard TR, Reichholf B, Rhie SK, Jude J, Moussa HF, Zuber J, Bell O. Parallel PRC2/cPRC1 and vPRC1 pathways silence lineage-specific genes and maintain self-renewal in mouse embryonic stem cells. SCIENCE ADVANCES 2020; 6:eaax5692. [PMID: 32270030 PMCID: PMC7112768 DOI: 10.1126/sciadv.aax5692] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Accepted: 01/09/2020] [Indexed: 05/29/2023]
Abstract
The transcriptional repressors Polycomb repressive complex 1 (PRC1) and PRC2 are required to maintain cell fate during embryonic development. PRC1 and PRC2 catalyze distinct histone modifications, establishing repressive chromatin at shared targets. How PRC1, which consists of canonical PRC1 (cPRC1) and variant PRC1 (vPRC1) complexes, and PRC2 cooperate to silence genes and support mouse embryonic stem cell (mESC) self-renewal is unclear. Using combinatorial genetic perturbations, we show that independent pathways of cPRC1 and vPRC1 are responsible for maintenance of H2A monoubiquitylation and silencing of shared target genes. Individual loss of PRC2-dependent cPRC1 or PRC2-independent vPRC1 disrupts only one pathway and does not impair mESC self-renewal capacity. However, loss of both pathways leads to mESC differentiation and activation of a subset of lineage-specific genes co-occupied by relatively high levels of PRC1/PRC2. Thus, parallel pathways explain the differential requirements for PRC1 and PRC2 and provide robust silencing of lineage-specific genes.
Collapse
Affiliation(s)
- J. A. Zepeda-Martinez
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna BioCenter (VBC), 1030 Vienna, Austria
| | - C. Pribitzer
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna BioCenter (VBC), 1030 Vienna, Austria
| | - J. Wang
- Research Institute of Molecular Pathology (IMP), Vienna BioCenter (VBC), 1030 Vienna, Austria
| | - D. Bsteh
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna BioCenter (VBC), 1030 Vienna, Austria
- Department of Biochemistry and Molecular Medicine, Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - S. Golumbeanu
- Department of Biochemistry and Molecular Medicine, Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Q. Zhao
- Department of Biochemistry and Molecular Medicine, Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - T. R. Burkard
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna BioCenter (VBC), 1030 Vienna, Austria
- Research Institute of Molecular Pathology (IMP), Vienna BioCenter (VBC), 1030 Vienna, Austria
| | - B. Reichholf
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna BioCenter (VBC), 1030 Vienna, Austria
| | - S. K. Rhie
- Department of Biochemistry and Molecular Medicine, Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - J. Jude
- Research Institute of Molecular Pathology (IMP), Vienna BioCenter (VBC), 1030 Vienna, Austria
| | - H. F. Moussa
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna BioCenter (VBC), 1030 Vienna, Austria
| | - J. Zuber
- Research Institute of Molecular Pathology (IMP), Vienna BioCenter (VBC), 1030 Vienna, Austria
| | - O. Bell
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna BioCenter (VBC), 1030 Vienna, Austria
- Department of Biochemistry and Molecular Medicine, Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| |
Collapse
|
97
|
Boettiger A, Murphy S. Advances in Chromatin Imaging at Kilobase-Scale Resolution. Trends Genet 2020; 36:273-287. [PMID: 32007290 PMCID: PMC7197267 DOI: 10.1016/j.tig.2019.12.010] [Citation(s) in RCA: 82] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Revised: 12/12/2019] [Accepted: 12/20/2019] [Indexed: 12/17/2022]
Abstract
It is now widely appreciated that the spatial organization of the genome is nonrandom, and its complex 3D folding has important consequences for many genome processes. Recent developments in multiplexed, super-resolution microscopy have enabled an unprecedented view of the polymeric structure of chromatin - from the loose folds of whole chromosomes to the detailed loops of cis-regulatory elements that regulate gene expression. Facilitated by the use of robotics, microfluidics, and improved approaches to super-resolution, thousands to hundreds of thousands of individual cells can now be analyzed in an individual experiment. This has led to new insights into the nature of genomic structural features identified by sequencing, such as topologically associated domains (TADs), and the nature of enhancer-promoter interactions underlying transcriptional regulation. We review these recent improvements.
Collapse
Affiliation(s)
- Alistair Boettiger
- Department of Developmental Biology, Stanford University, Stanford, CA 94305, USA.
| | - Sedona Murphy
- Department of Genetics, Stanford University, Stanford, CA 94305, USA
| |
Collapse
|
98
|
RYBP/YAF2-PRC1 complexes and histone H1-dependent chromatin compaction mediate propagation of H2AK119ub1 during cell division. Nat Cell Biol 2020; 22:439-452. [PMID: 32203418 DOI: 10.1038/s41556-020-0484-1] [Citation(s) in RCA: 59] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2019] [Accepted: 02/14/2020] [Indexed: 01/12/2023]
Abstract
Stable propagation of epigenetic information is important for maintaining cell identity in multicellular organisms. However, it remains largely unknown how mono-ubiquitinated histone H2A on lysine 119 (H2AK119ub1) is established and stably propagated during cell division. In this study, we found that the proteins RYBP and YAF2 each specifically bind H2AK119ub1 to recruit the RYBP-PRC1 or YAF2-PRC1 complex to catalyse the ubiquitination of H2A on neighbouring nucleosomes through a positive-feedback model. Additionally, we demonstrated that histone H1-compacted chromatin enhances the distal propagation of H2AK119ub1, thereby reinforcing the inheritance of H2AK119ub1 during cell division. Moreover, we showed that either disruption of RYBP/YAF2-PRC1 activity or impairment of histone H1-dependent chromatin compaction resulted in a significant defect of the maintenance of H2AK119ub1. Therefore, our results suggest that histone H1-dependent chromatin compaction plays a critical role in the stable propagation of H2AK119ub1 by RYBP/YAF2-PRC1 during cell division.
Collapse
|
99
|
Somasundaram L, Levy S, Hussein AM, Ehnes DD, Mathieu J, Ruohola-Baker H. Epigenetic metabolites license stem cell states. Curr Top Dev Biol 2020; 138:209-240. [PMID: 32220298 DOI: 10.1016/bs.ctdb.2020.02.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
It has become clear during recent years that stem cells undergo metabolic remodeling during their activation process. While these metabolic switches take place in pluripotency as well as adult stem cell populations, the rules that govern the switch are not clear. In this review, we summarize some of the transitions in adult and pluripotent cell types and will propose that the key function in this process is the generation of epigenetic metabolites that govern critical epigenetic modifications, and therefore stem cell states.
Collapse
Affiliation(s)
- Logeshwaran Somasundaram
- Department of Biochemistry, University of Washington, Seattle, WA, United States; Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA, United States
| | - Shiri Levy
- Department of Biochemistry, University of Washington, Seattle, WA, United States; Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA, United States
| | - Abdiasis M Hussein
- Department of Biochemistry, University of Washington, Seattle, WA, United States; Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA, United States
| | - Devon D Ehnes
- Department of Biochemistry, University of Washington, Seattle, WA, United States; Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA, United States
| | - Julie Mathieu
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA, United States; Department of Comparative Medicine, University of Washington, Seattle, WA, United States
| | - Hannele Ruohola-Baker
- Department of Biochemistry, University of Washington, Seattle, WA, United States; Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA, United States.
| |
Collapse
|
100
|
Dunican DS, Mjoseng HK, Duthie L, Flyamer IM, Bickmore WA, Meehan RR. Bivalent promoter hypermethylation in cancer is linked to the H327me3/H3K4me3 ratio in embryonic stem cells. BMC Biol 2020; 18:25. [PMID: 32131813 PMCID: PMC7057567 DOI: 10.1186/s12915-020-0752-3] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Accepted: 02/14/2020] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND Thousands of mammalian promoters are defined by co-enrichment of the histone tail modifications H3K27me3 (repressive) and H3K4me3 (activating) and are thus termed bivalent. It was previously observed that bivalent genes in human ES cells (hESC) are frequent targets for hypermethylation in human cancers, and depletion of DNA methylation in mouse embryonic stem cells has a marked impact on H3K27me3 distribution at bivalent promoters. However, only a fraction of bivalent genes in stem cells are targets of hypermethylation in cancer, and it is currently unclear whether all bivalent promoters are equally sensitive to DNA hypomethylation and whether H3K4me3 levels play a role in the interplay between DNA methylation and H3K27me3. RESULTS We report the sub-classification of bivalent promoters into two groups-promoters with a high H3K27me3:H3K4me3 (hiBiv) ratio or promoters with a low H3K27me3:H3K4me3 ratio (loBiv). HiBiv are enriched in canonical Polycomb components, show a higher degree of local intrachromosomal contacts and are highly sensitive to DNA hypomethylation in terms of H3K27me3 depletion from broad Polycomb domains. In contrast, loBiv promoters are enriched in non-canonical Polycomb components, show lower intrachromosomal contacts and are less sensitive to DNA hypomethylation at the same genomic resolution. Multiple systems reveal that hiBiv promoters are more depleted of Polycomb complexes than loBiv promoters following a reduction in DNA methylation, and we demonstrate that H3K27me3 re-accumulates at promoters when DNA methylation is restored. In human cancer, we show that hiBiv promoters lose H3K27me3 and are more susceptible to DNA hypermethylation than loBiv promoters. CONCLUSION We conclude that bivalency as a general term to describe mammalian promoters is an over-simplification and our sub-classification has revealed novel insights into the interplay between the largely antagonistic presence of DNA methylation and Polycomb systems at bivalent promoters. This approach redefines molecular pathologies underlying disease in which global DNA methylation is aberrant or where Polycomb mutations are present.
Collapse
Affiliation(s)
- Donnchadh S. Dunican
- MRC Human Genetics Unit, MRC IGMM, University of Edinburgh, Western General Hospital, Crewe Road, Edinburgh, EH4 2XU Scotland
| | - Heidi K. Mjoseng
- MRC Human Genetics Unit, MRC IGMM, University of Edinburgh, Western General Hospital, Crewe Road, Edinburgh, EH4 2XU Scotland
| | - Leanne Duthie
- MRC Human Genetics Unit, MRC IGMM, University of Edinburgh, Western General Hospital, Crewe Road, Edinburgh, EH4 2XU Scotland
| | - Ilya M. Flyamer
- MRC Human Genetics Unit, MRC IGMM, University of Edinburgh, Western General Hospital, Crewe Road, Edinburgh, EH4 2XU Scotland
| | - Wendy A. Bickmore
- MRC Human Genetics Unit, MRC IGMM, University of Edinburgh, Western General Hospital, Crewe Road, Edinburgh, EH4 2XU Scotland
| | - Richard R. Meehan
- MRC Human Genetics Unit, MRC IGMM, University of Edinburgh, Western General Hospital, Crewe Road, Edinburgh, EH4 2XU Scotland
| |
Collapse
|