1
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Ciapponi M, Karlukova E, Schkölziger S, Benda C, Müller J. Structural basis of the histone ubiquitination read-write mechanism of RYBP-PRC1. Nat Struct Mol Biol 2024; 31:1023-1027. [PMID: 38528151 PMCID: PMC11257959 DOI: 10.1038/s41594-024-01258-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Accepted: 02/26/2024] [Indexed: 03/27/2024]
Abstract
Histone H2A monoubiquitination (H2Aub1) by the PRC1 subunit RING1B entails a positive feedback loop, mediated by the RING1B-interacting protein RYBP. We uncover that human RYBP-PRC1 binds unmodified nucleosomes via RING1B but H2Aub1-modified nucleosomes via RYBP. RYBP interactions with both ubiquitin and the nucleosome acidic patch create the high binding affinity that favors RYBP- over RING1B-directed PRC1 binding to H2Aub1-modified nucleosomes; this enables RING1B to monoubiquitinate H2A in neighboring unmodified nucleosomes.
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Affiliation(s)
- Maria Ciapponi
- Laboratory of Chromatin Biology, Max-Planck Institute of Biochemistry, Martinsried, Germany
| | - Elena Karlukova
- Laboratory of Chromatin Biology, Max-Planck Institute of Biochemistry, Martinsried, Germany
| | - Sven Schkölziger
- Laboratory of Chromatin Biology, Max-Planck Institute of Biochemistry, Martinsried, Germany
| | - Christian Benda
- Department of Structural Cell Biology, Max-Planck Institute of Biochemistry, Martinsried, Germany.
| | - Jürg Müller
- Laboratory of Chromatin Biology, Max-Planck Institute of Biochemistry, Martinsried, Germany.
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2
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Nash JD, Muralidhar R, Yousaf A, Castilla M. Ossifying Fibromyxoid Tumor of the Shoulder: A Case Report. Cureus 2024; 16:e63309. [PMID: 39070435 PMCID: PMC11283310 DOI: 10.7759/cureus.63309] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2024] [Accepted: 06/26/2024] [Indexed: 07/30/2024] Open
Abstract
Ossifying fibromyxoid tumor (OFMT) is a rare, slow-growing, mesenchymal tumor with intermediate malignant potential, predominantly affecting middle-aged individuals. Histologically, it presents as a fibrous capsule or pseudocapsule, with a complete or incomplete lamellar bone shell surrounding oval/polygonal cells within a fibromyxoid matrix. Advances in immunohistochemistry have facilitated OFMT identification, with S100 protein expression and INI-1 loss being notable features. CD10 expression is also reported in a small minority of cases. Recent studies highlight a translocation of the PHF-1 gene, proposing a possible etiology for tumorigenesis. Treatment involves wide excision, with long-term follow-up for recurrence or metastasis. In this case, a 61-year-old White male presented to the outpatient surgical office with a painless mass on his right shoulder. The patient reported that the mass first appeared three to four years prior and that it had been growing slowly since the initial presentation. On examination, the patient had a well-circumscribed, 1.5 x 1.5 cm, soft, nontender, nonmobile subcutaneous mass on his right shoulder. The mass was initially suspected to be a subcutaneous cyst based on physical exam, but surgical excision and histopathology established the diagnosis of OFMT that extended to the margins of the specimen. The patient underwent a wider excision for margins and has had a benign postoperative course. The patient was referred to dermatology and oncology for continuation of care. This case demonstrates the necessity for a thorough work-up, appropriate excision, and histopathologic examination to rule in diagnoses of lower incidence with the potential for a worse prognosis. Appropriate and timely diagnoses can guide proper screening for cancer recurrence and management.
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Affiliation(s)
- Joel D Nash
- Medicine, Nova Southeastern University Dr. Kiran C. Patel College of Osteopathic Medicine, Fort Lauderdale, USA
| | - Rohit Muralidhar
- Medicine, Nova Southeastern University Dr. Kiran C. Patel College of Osteopathic Medicine, Fort Lauderdale, USA
| | - Abdullah Yousaf
- Medicine, William Carey University College of Osteopathic Medicine, Hattiesburg, USA
| | - Maria Castilla
- General Surgery, HCA Florida Fawcett Hospital, Port Charlotte, USA
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3
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Wachtel M, Surdez D, Grünewald TGP, Schäfer BW. Functional Classification of Fusion Proteins in Sarcoma. Cancers (Basel) 2024; 16:1355. [PMID: 38611033 PMCID: PMC11010897 DOI: 10.3390/cancers16071355] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2024] [Revised: 03/25/2024] [Accepted: 03/27/2024] [Indexed: 04/14/2024] Open
Abstract
Sarcomas comprise a heterogeneous group of malignant tumors of mesenchymal origin. More than 80 entities are associated with different mesenchymal lineages. Sarcomas with fibroblastic, muscle, bone, vascular, adipocytic, and other characteristics are distinguished. Nearly half of all entities contain specific chromosomal translocations that give rise to fusion proteins. These are mostly pathognomonic, and their detection by various molecular techniques supports histopathologic classification. Moreover, the fusion proteins act as oncogenic drivers, and their blockade represents a promising therapeutic approach. This review summarizes the current knowledge on fusion proteins in sarcoma. We categorize the different fusion proteins into functional classes, including kinases, epigenetic regulators, and transcription factors, and describe their mechanisms of action. Interestingly, while fusion proteins acting as transcription factors are found in all mesenchymal lineages, the others have a more restricted pattern. Most kinase-driven sarcomas belong to the fibroblastic/myofibroblastic lineage. Fusion proteins with an epigenetic function are mainly associated with sarcomas of unclear differentiation, suggesting that epigenetic dysregulation leads to a major change in cell identity. Comparison of mechanisms of action reveals recurrent functional modes, including antagonism of Polycomb activity by fusion proteins with epigenetic activity and recruitment of histone acetyltransferases by fusion transcription factors of the myogenic lineage. Finally, based on their biology, we describe potential approaches to block the activity of fusion proteins for therapeutic intervention. Overall, our work highlights differences as well as similarities in the biology of fusion proteins from different sarcomas and provides the basis for a functional classification.
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Affiliation(s)
- Marco Wachtel
- Department of Oncology and Children’s Research Center, University Children’s Hospital, Steinwiesstrasse 75, CH-8032 Zurich, Switzerland
| | - Didier Surdez
- Balgrist University Hospital, Faculty of Medicine, University of Zurich (UZH), CH-8008 Zurich, Switzerland
| | - Thomas G. P. Grünewald
- Division of Translational Pediatric Sarcoma Research, German Cancer Research Center (DKFZ), German Cancer Consortium (DKTK), 69120 Heidelberg, Germany
- Hopp-Children’s Cancer Center (KiTZ), 69120 Heidelberg, Germany
- National Center for Tumor Diseases (NCT), NCT Heidelberg, a Partnership between DKFZ and Heidelberg University Hospital, 69120 Heidelberg, Germany
- Institute of Pathology, Heidelberg University Hospital, 69120 Heidelberg, Germany
| | - Beat W. Schäfer
- Department of Oncology and Children’s Research Center, University Children’s Hospital, Steinwiesstrasse 75, CH-8032 Zurich, Switzerland
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4
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Li Y, Mo Y, Chen C, He J, Guo Z. Research advances of polycomb group proteins in regulating mammalian development. Front Cell Dev Biol 2024; 12:1383200. [PMID: 38505258 PMCID: PMC10950033 DOI: 10.3389/fcell.2024.1383200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2024] [Accepted: 02/26/2024] [Indexed: 03/21/2024] Open
Abstract
Polycomb group (PcG) proteins are a subset of epigenetic factors that are highly conserved throughout evolution. In mammals, PcG proteins can be classified into two muti-proteins complexes: Polycomb repressive complex 1 (PRC1) and PRC2. Increasing evidence has demonstrated that PcG complexes play critical roles in the regulation of gene expression, genomic imprinting, chromosome X-inactivation, and chromatin structure. Accordingly, the dysfunction of PcG proteins is tightly orchestrated with abnormal developmental processes. Here, we summarized and discussed the current knowledge of the biochemical and molecular functions of PcG complexes, especially the PRC1 and PRC2 in mammalian development including embryonic development and tissue development, which will shed further light on the deep understanding of the basic knowledge of PcGs and their functions for reproductive health and developmental disorders.
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Affiliation(s)
| | | | | | - Jin He
- Department of Obstetrics and Gynecology, The First Hospital of Jilin University, Changchun, Jilin, China
| | - Zhiheng Guo
- Department of Obstetrics and Gynecology, The First Hospital of Jilin University, Changchun, Jilin, China
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5
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Ito S, Umehara T, Koseki H. Polycomb-mediated histone modifications and gene regulation. Biochem Soc Trans 2024; 52:151-161. [PMID: 38288743 DOI: 10.1042/bst20230336] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2023] [Revised: 01/03/2024] [Accepted: 01/05/2024] [Indexed: 02/29/2024]
Abstract
Polycomb repressive complexes 1 and 2 (PRC1 and PRC2) are transcriptional repressor complexes that play a fundamental role in epigenomic regulation and the cell-fate decision; these complexes are widely conserved in multicellular organisms. PRC1 is an E3 ubiquitin (ub) ligase that generates histone H2A ubiquitinated at lysine (K) 119 (H2AK119ub1), whereas PRC2 is a histone methyltransferase that specifically catalyzes tri-methylation of histone H3K27 (H3K27me3). Genome-wide analyses have confirmed that these two key epigenetic marks highly overlap across the genome and contribute to gene repression. We are now beginning to understand the molecular mechanisms that enable PRC1 and PRC2 to identify their target sites in the genome and communicate through feedback mechanisms to create Polycomb chromatin domains. Recently, it has become apparent that PRC1-induced H2AK119ub1 not only serves as a docking site for PRC2 but also affects the dynamics of the H3 tail, both of which enhance PRC2 activity, suggesting that trans-tail communication between H2A and H3 facilitates the formation of the Polycomb chromatin domain. In this review, we discuss the emerging principles that define how PRC1 and PRC2 establish the Polycomb chromatin domain and regulate gene expression in mammals.
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Affiliation(s)
- Shinsuke Ito
- Laboratory of Developmental Genetics, RIKEN Center for Integrative Medical Sciences, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan
| | - Takashi Umehara
- Laboratory of Developmental Genetics, RIKEN Center for Integrative Medical Sciences, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan
- Laboratory for Epigenetics Drug Discovery, RIKEN Center for Biosystems Dynamics Research, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan
| | - Haruhiko Koseki
- Laboratory of Developmental Genetics, RIKEN Center for Integrative Medical Sciences, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan
- Department of Cellular and Molecular Medicine, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670, Japan
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6
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Cookis T, Lydecker A, Sauer P, Kasinath V, Nogales E. Structural basis for the inhibition of PRC2 by active transcription histone posttranslational modifications. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.09.579730. [PMID: 38370759 PMCID: PMC10871338 DOI: 10.1101/2024.02.09.579730] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/20/2024]
Abstract
Polycomb repressive complex 2 (PRC2) is an epigenetic regulator essential for embryonic development and maintenance of cell identity that trimethylates histone H3 at lysine 27 (H3K27me3) leading to gene silencing. PRC2 is regulated by association with protein cofactors and crosstalk with histone posttranslational modifications. Trimethylated histone H3 K4 (H3K4me3) and K36 (H3K36me3) localize to sites of active transcription where H3K27me3 is absent and inhibit PRC2 activity through unknown mechanisms. Using cryo-electron microscopy we reveal that histone H3 tails modified with H3K36me3 engage poorly with the PRC2 active site and preclude its effective interaction with chromatin, while the H3K4me3 modification binds to the allosteric site in the EED subunit, acting as an antagonist that competes with allosteric activators required for the spreading of the H3K27me3 repressive mark. Thus, the location along the H3 tail of the H3K4me3 and H3K36me3 modifications allow them to target two essential requirements for efficient trimethylation of histone H3K27. We further show that the JARID2 cofactor modulates PRC2 activity in the presence of these histone modifications.
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Affiliation(s)
- Trinity Cookis
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720
| | - Alexandria Lydecker
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720
| | - Paul Sauer
- California Institute for Quantitative Biosciences (QB3), University of California, Berkeley, CA 94720
- Howard Hughes Medical Institute, University of California, Berkeley, CA 94720
| | - Vignesh Kasinath
- Department of Biochemistry, University of Colorado, Boulder, CO 80303
| | - Eva Nogales
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720
- California Institute for Quantitative Biosciences (QB3), University of California, Berkeley, CA 94720
- Molecular Biophysics and Integrative Bio-Imaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720
- Howard Hughes Medical Institute, University of California, Berkeley, CA 94720
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7
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Ingersoll S, Trouth A, Luo X, Espinoza A, Wen J, Tucker J, Astatike K, Phiel CJ, Kutateladze TG, Wu TP, Ramachandran S, Ren X. Sparse CBX2 nucleates many Polycomb proteins to promote facultative heterochromatinization of Polycomb target genes. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.05.578969. [PMID: 38370615 PMCID: PMC10871256 DOI: 10.1101/2024.02.05.578969] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/20/2024]
Abstract
Facultative heterochromatinization of genomic regulators by Polycomb repressive complex (PRC) 1 and 2 is essential in development and differentiation; however, the underlying molecular mechanisms remain obscure. Using genetic engineering, molecular approaches, and live-cell single-molecule imaging, we quantify the number of proteins within condensates formed through liquid-liquid phase separation (LLPS) and find that in mouse embryonic stem cells (mESCs), approximately 3 CBX2 proteins nucleate many PRC1 and PRC2 subunits to form one non-stoichiometric condensate. We demonstrate that sparse CBX2 prevents Polycomb proteins from migrating to constitutive heterochromatin, demarcates the spatial boundaries of facultative heterochromatin, controls the deposition of H3K27me3, regulates transcription, and impacts cellular differentiation. Furthermore, we show that LLPS of CBX2 is required for the demarcation and deposition of H3K27me3 and is essential for cellular differentiation. Our findings uncover new functional roles of LLPS in the formation of facultative heterochromatin and unravel a new mechanism by which low-abundant proteins nucleate many other proteins to form compartments that enable them to execute their functions.
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Affiliation(s)
- Steven Ingersoll
- Department of Chemistry, University of Colorado Denver, Denver, CO 80217-3364, USA
| | - Abby Trouth
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO, USA
| | - Xinlong Luo
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Axel Espinoza
- Department of Integrative Biology, University of Colorado Denver, CO 80217-3364, USA
| | - Joey Wen
- Department of Chemistry, University of Colorado Denver, Denver, CO 80217-3364, USA
| | - Joseph Tucker
- Department of Integrative Biology, University of Colorado Denver, CO 80217-3364, USA
| | - Kalkidan Astatike
- Department of Chemistry, University of Colorado Denver, Denver, CO 80217-3364, USA
| | - Christopher J. Phiel
- Department of Integrative Biology, University of Colorado Denver, CO 80217-3364, USA
| | - Tatiana G. Kutateladze
- Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Tao P. Wu
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Srinivas Ramachandran
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO, USA
- RNA Bioscience Initiative, University of Colorado School of Medicine, Aurora, CO, USA
| | - Xiaojun Ren
- Department of Chemistry, University of Colorado Denver, Denver, CO 80217-3364, USA
- Department of Integrative Biology, University of Colorado Denver, CO 80217-3364, USA
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8
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Nagpal H, Ali-Ahmad A, Hirano Y, Cai W, Halic M, Fukagawa T, Sekulić N, Fierz B. CENP-A and CENP-B collaborate to create an open centromeric chromatin state. Nat Commun 2023; 14:8227. [PMID: 38086807 PMCID: PMC10716449 DOI: 10.1038/s41467-023-43739-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2022] [Accepted: 11/17/2023] [Indexed: 12/18/2023] Open
Abstract
Centromeres are epigenetically defined via the presence of the histone H3 variant CENP-A. Contacting CENP-A nucleosomes, the constitutive centromere associated network (CCAN) and the kinetochore assemble, connecting the centromere to spindle microtubules during cell division. The DNA-binding centromeric protein CENP-B is involved in maintaining centromere stability and, together with CENP-A, shapes the centromeric chromatin state. The nanoscale organization of centromeric chromatin is not well understood. Here, we use single-molecule fluorescence and cryoelectron microscopy (cryoEM) to show that CENP-A incorporation establishes a dynamic and open chromatin state. The increased dynamics of CENP-A chromatin create an opening for CENP-B DNA access. In turn, bound CENP-B further opens the chromatin fiber structure and induces nucleosomal DNA unwrapping. Finally, removal of CENP-A increases CENP-B mobility in cells. Together, our studies show that the two centromere-specific proteins collaborate to reshape chromatin structure, enabling the binding of centromeric factors and establishing a centromeric chromatin state.
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Affiliation(s)
- Harsh Nagpal
- École Polytechnique Fédérale de Lausanne (EPFL), SB ISIC LCBM, Station 6, CH-1015, Lausanne, Switzerland
| | - Ahmad Ali-Ahmad
- Centre for Molecular Medicine Norway (NCMM), Nordic EMBL Partnership, Faculty of Medicine, University of Oslo, Oslo, 0318, Norway
| | - Yasuhiro Hirano
- Graduate School of Frontier Biosciences, Osaka University, Suita, 565-0871, Japan
| | - Wei Cai
- École Polytechnique Fédérale de Lausanne (EPFL), SB ISIC LCBM, Station 6, CH-1015, Lausanne, Switzerland
| | - Mario Halic
- Structural Biology, St. Jude Children's Research Hospital, Memphis, TN, 38105-3678, USA
| | - Tatsuo Fukagawa
- Graduate School of Frontier Biosciences, Osaka University, Suita, 565-0871, Japan
| | - Nikolina Sekulić
- Centre for Molecular Medicine Norway (NCMM), Nordic EMBL Partnership, Faculty of Medicine, University of Oslo, Oslo, 0318, Norway.
- Department of Chemistry, University of Oslo, P.O. Box 1033, Blindern, 0315, Norway.
| | - Beat Fierz
- École Polytechnique Fédérale de Lausanne (EPFL), SB ISIC LCBM, Station 6, CH-1015, Lausanne, Switzerland.
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9
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Lu G, Li P. PHF1 compartmentalizes PRC2 via phase separation. Biochem J 2023; 480:1833-1844. [PMID: 37888776 DOI: 10.1042/bcj20230040] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2023] [Revised: 10/25/2023] [Accepted: 10/26/2023] [Indexed: 10/28/2023]
Abstract
Polycomb repressive complex 2 (PRC2) is central to polycomb repression as it trimethylates lysine 27 on histone H3 (H3K27me3). How PRC2 is recruited to its targets to deposit H3K27me3 remains an open question. Polycomb-like (PCL) proteins, a group of conserved PRC2 accessory proteins, can direct PRC2 to its targets. In this report, we demonstrate that a PCL protein named PHF1 forms phase-separated condensates at H3K27me3 loci that recruit PRC2. Combining cellular observation and biochemical reconstitution, we show that the N-terminal domains of PHF1 cooperatively mediate target recognition, the chromo-like domain recruits PRC2, and the intrinsically disordered region (IDR) drives phase separation. Moreover, we reveal that the condensates compartmentalize PRC2, DNA, and nucleosome arrays by phase separation. Luciferase reporter assays confirm that PHF1 phase separation promotes transcription repression, further supporting a role of the condensates in polycomb repression. Based on our findings, we propose that these condensates create favorable microenvironments at the target loci for PRC2 to function.
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Affiliation(s)
- Genzhe Lu
- Beijing Frontier Research Center for Biological Structure, School of Life Sciences, Tsinghua University, Beijing 100084, China
- Tsinghua-Peking Joint Center for Life Sciences, Beijing 100084, China
- Tsinghua Xuetang Life Science Program, Tsinghua University, Beijing 100084, China
| | - Pilong Li
- Beijing Frontier Research Center for Biological Structure, School of Life Sciences, Tsinghua University, Beijing 100084, China
- Tsinghua-Peking Joint Center for Life Sciences, Beijing 100084, China
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10
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Barrasa JI, Kahn TG, Lundkvist MJ, Schwartz YB. DNA elements tether canonical Polycomb Repressive Complex 1 to human genes. Nucleic Acids Res 2023; 51:11613-11633. [PMID: 37855680 PMCID: PMC10681801 DOI: 10.1093/nar/gkad889] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Revised: 09/25/2023] [Accepted: 10/11/2023] [Indexed: 10/20/2023] Open
Abstract
Development of multicellular animals requires epigenetic repression by Polycomb group proteins. The latter assemble in multi-subunit complexes, of which two kinds, Polycomb Repressive Complex 1 (PRC1) and Polycomb Repressive Complex 2 (PRC2), act together to repress key developmental genes. How PRC1 and PRC2 recognize specific genes remains an open question. Here we report the identification of several hundreds of DNA elements that tether canonical PRC1 to human developmental genes. We use the term tether to describe a process leading to a prominent presence of canonical PRC1 at certain genomic sites, although the complex is unlikely to interact with DNA directly. Detailed analysis indicates that sequence features associated with PRC1 tethering differ from those that favour PRC2 binding. Throughout the genome, the two kinds of sequence features mix in different proportions to yield a gamut of DNA elements that range from those tethering predominantly PRC1 or PRC2 to ones capable of tethering both complexes. The emerging picture is similar to the paradigmatic targeting of Polycomb complexes by Polycomb Response Elements (PREs) of Drosophila but providing for greater plasticity.
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Affiliation(s)
- Juan I Barrasa
- Department of Molecular Biology, Umeå University, 901 87 Umeå, Sweden
| | - Tatyana G Kahn
- Department of Molecular Biology, Umeå University, 901 87 Umeå, Sweden
| | - Moa J Lundkvist
- Department of Molecular Biology, Umeå University, 901 87 Umeå, Sweden
| | - Yuri B Schwartz
- Department of Molecular Biology, Umeå University, 901 87 Umeå, Sweden
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11
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Ngubo M, Moradi F, Ito CY, Stanford WL. Tissue-Specific Tumour Suppressor and Oncogenic Activities of the Polycomb-like Protein MTF2. Genes (Basel) 2023; 14:1879. [PMID: 37895228 PMCID: PMC10606531 DOI: 10.3390/genes14101879] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Revised: 09/22/2023] [Accepted: 09/23/2023] [Indexed: 10/29/2023] Open
Abstract
The Polycomb repressive complex 2 (PRC2) is a conserved chromatin-remodelling complex that catalyses the trimethylation of histone H3 lysine 27 (H3K27me3), a mark associated with gene silencing. PRC2 regulates chromatin structure and gene expression during organismal and tissue development and tissue homeostasis in the adult. PRC2 core subunits are associated with various accessory proteins that modulate its function and recruitment to target genes. The multimeric composition of accessory proteins results in two distinct variant complexes of PRC2, PRC2.1 and PRC2.2. Metal response element-binding transcription factor 2 (MTF2) is one of the Polycomb-like proteins (PCLs) that forms the PRC2.1 complex. MTF2 is highly conserved, and as an accessory subunit of PRC2, it has important roles in embryonic stem cell self-renewal and differentiation, development, and cancer progression. Here, we review the impact of MTF2 in PRC2 complex assembly, catalytic activity, and spatiotemporal function. The emerging paradoxical evidence suggesting that MTF2 has divergent roles as either a tumour suppressor or an oncogene in different tissues merits further investigations. Altogether, our review illuminates the context-dependent roles of MTF2 in Polycomb group (PcG) protein-mediated epigenetic regulation. Its impact on disease paves the way for a deeper understanding of epigenetic regulation and novel therapeutic strategies.
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Affiliation(s)
- Mzwanele Ngubo
- The Sprott Centre for Stem Cell Research, Ottawa Hospital Research Institute, Ottawa, ON K1H 8L6, Canada
- Ottawa Institute of Systems Biology, Ottawa, ON K1H 8M5, Canada
| | - Fereshteh Moradi
- The Sprott Centre for Stem Cell Research, Ottawa Hospital Research Institute, Ottawa, ON K1H 8L6, Canada
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON K1N 6N5, Canada
| | - Caryn Y. Ito
- The Sprott Centre for Stem Cell Research, Ottawa Hospital Research Institute, Ottawa, ON K1H 8L6, Canada
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON K1N 6N5, Canada
| | - William L. Stanford
- The Sprott Centre for Stem Cell Research, Ottawa Hospital Research Institute, Ottawa, ON K1H 8L6, Canada
- Ottawa Institute of Systems Biology, Ottawa, ON K1H 8M5, Canada
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON K1N 6N5, Canada
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, ON K1H 8M5, Canada
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12
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Kwok HS, Freedy AM, Siegenfeld AP, Morriss JW, Waterbury AL, Kissler SM, Liau BB. Drug addiction unveils a repressive methylation ceiling in EZH2-mutant lymphoma. Nat Chem Biol 2023; 19:1105-1115. [PMID: 36973442 PMCID: PMC10522050 DOI: 10.1038/s41589-023-01299-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Accepted: 02/23/2023] [Indexed: 03/29/2023]
Abstract
Drug addiction, a phenomenon where cancer cells paradoxically depend on continuous drug treatment for survival, has uncovered cell signaling mechanisms and cancer codependencies. Here we discover mutations that confer drug addiction to inhibitors of the transcriptional repressor polycomb repressive complex 2 (PRC2) in diffuse large B-cell lymphoma. Drug addiction is mediated by hypermorphic mutations in the CXC domain of the catalytic subunit EZH2, which maintain H3K27me3 levels even in the presence of PRC2 inhibitors. Discontinuation of inhibitor treatment leads to overspreading of H3K27me3, surpassing a repressive methylation ceiling compatible with lymphoma cell survival. Exploiting this vulnerability, we show that inhibition of SETD2 similarly induces the spread of H3K27me3 and blocks lymphoma growth. Collectively, our findings demonstrate that constraints on chromatin landscapes can yield biphasic dependencies in epigenetic signaling in cancer cells. More broadly, we highlight how approaches to identify drug addiction mutations can be leveraged to discover cancer vulnerabilities.
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Affiliation(s)
- Hui Si Kwok
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Allyson M Freedy
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Allison P Siegenfeld
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Julia W Morriss
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Amanda L Waterbury
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Stephen M Kissler
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - Brian B Liau
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA.
- Broad Institute of MIT and Harvard, Cambridge, MA, USA.
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13
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Franco-Echevarría E, Nielsen M, Schulten A, Cheema J, Morgan TE, Bienz M, Dean C. Distinct accessory roles of Arabidopsis VEL proteins in Polycomb silencing. Genes Dev 2023; 37:801-817. [PMID: 37734835 PMCID: PMC7615239 DOI: 10.1101/gad.350814.123] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Accepted: 08/31/2023] [Indexed: 09/23/2023]
Abstract
Polycomb repressive complex 2 (PRC2) mediates epigenetic silencing of target genes in animals and plants. In Arabidopsis, PRC2 is required for the cold-induced epigenetic silencing of the FLC floral repressor locus to align flowering with spring. During this process, PRC2 relies on VEL accessory factors, including the constitutively expressed VRN5 and the cold-induced VIN3. The VEL proteins are physically associated with PRC2, but their individual functions remain unclear. Here, we show an intimate association between recombinant VRN5 and multiple components within a reconstituted PRC2, dependent on a compact conformation of VRN5 central domains. Key residues mediating this compact conformation are conserved among VRN5 orthologs across the plant kingdom. In contrast, VIN3 interacts with VAL1, a transcriptional repressor that binds directly to FLC These associations differentially affect their role in H3K27me deposition: Both proteins are required for H3K27me3, but only VRN5 is necessary for H3K27me2. Although originally defined as vernalization regulators, VIN3 and VRN5 coassociate with many targets in the Arabidopsis genome that are modified with H3K27me3. Our work therefore reveals the distinct accessory roles for VEL proteins in conferring cold-induced silencing on FLC, with broad relevance for PRC2 targets generally.
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Affiliation(s)
- Elsa Franco-Echevarría
- Medical Research Council Laboratory of Molecular Biology, Cambridge CB2 0QH, United Kingdom
- John Innes Centre, Norwich Research Park, Norwich NR4 7UH, United Kingdom
| | - Mathias Nielsen
- John Innes Centre, Norwich Research Park, Norwich NR4 7UH, United Kingdom
| | - Anna Schulten
- John Innes Centre, Norwich Research Park, Norwich NR4 7UH, United Kingdom
| | - Jitender Cheema
- John Innes Centre, Norwich Research Park, Norwich NR4 7UH, United Kingdom
| | - Tomos E Morgan
- Medical Research Council Laboratory of Molecular Biology, Cambridge CB2 0QH, United Kingdom
| | - Mariann Bienz
- Medical Research Council Laboratory of Molecular Biology, Cambridge CB2 0QH, United Kingdom;
| | - Caroline Dean
- Medical Research Council Laboratory of Molecular Biology, Cambridge CB2 0QH, United Kingdom;
- John Innes Centre, Norwich Research Park, Norwich NR4 7UH, United Kingdom
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14
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Wenger A, Biran A, Alcaraz N, Redó-Riveiro A, Sell AC, Krautz R, Flury V, Reverón-Gómez N, Solis-Mezarino V, Völker-Albert M, Imhof A, Andersson R, Brickman JM, Groth A. Symmetric inheritance of parental histones governs epigenome maintenance and embryonic stem cell identity. Nat Genet 2023; 55:1567-1578. [PMID: 37666988 PMCID: PMC10484787 DOI: 10.1038/s41588-023-01476-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Accepted: 07/17/2023] [Indexed: 09/06/2023]
Abstract
Modified parental histones are segregated symmetrically to daughter DNA strands during replication and can be inherited through mitosis. How this may sustain the epigenome and cell identity remains unknown. Here we show that transmission of histone-based information during DNA replication maintains epigenome fidelity and embryonic stem cell plasticity. Asymmetric segregation of parental histones H3-H4 in MCM2-2A mutants compromised mitotic inheritance of histone modifications and globally altered the epigenome. This included widespread spurious deposition of repressive modifications, suggesting elevated epigenetic noise. Moreover, H3K9me3 loss at repeats caused derepression and H3K27me3 redistribution across bivalent promoters correlated with misexpression of developmental genes. MCM2-2A mutation challenged dynamic transitions in cellular states across the cell cycle, enhancing naïve pluripotency and reducing lineage priming in G1. Furthermore, developmental competence was diminished, correlating with impaired exit from pluripotency. Collectively, this argues that epigenetic inheritance of histone modifications maintains a correctly balanced and dynamic chromatin landscape able to support mammalian cell differentiation.
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Affiliation(s)
- Alice Wenger
- Novo Nordisk Foundation Center for Protein Research (CPR), University of Copenhagen, Copenhagen, Denmark
- Biotech Research and Innovation Centre (BRIC), University of Copenhagen, Copenhagen, Denmark
- Lexogen GmbH, Vienna, Austria
| | - Alva Biran
- Novo Nordisk Foundation Center for Protein Research (CPR), University of Copenhagen, Copenhagen, Denmark
- Biotech Research and Innovation Centre (BRIC), University of Copenhagen, Copenhagen, Denmark
| | - Nicolas Alcaraz
- Novo Nordisk Foundation Center for Protein Research (CPR), University of Copenhagen, Copenhagen, Denmark
- Section for Computational and RNA Biology, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Alba Redó-Riveiro
- Novo Nordisk Foundation Center for Stem Cell Medicine (reNEW), University of Copenhagen, Copenhagen, Denmark
| | - Annika Charlotte Sell
- Novo Nordisk Foundation Center for Stem Cell Medicine (reNEW), University of Copenhagen, Copenhagen, Denmark
| | - Robert Krautz
- Section for Computational and RNA Biology, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Valentin Flury
- Novo Nordisk Foundation Center for Protein Research (CPR), University of Copenhagen, Copenhagen, Denmark
- Biotech Research and Innovation Centre (BRIC), University of Copenhagen, Copenhagen, Denmark
| | - Nazaret Reverón-Gómez
- Novo Nordisk Foundation Center for Protein Research (CPR), University of Copenhagen, Copenhagen, Denmark
- Biotech Research and Innovation Centre (BRIC), University of Copenhagen, Copenhagen, Denmark
| | | | - Moritz Völker-Albert
- EpiQMAx GmbH, Planegg, Germany
- Faculty of Medicine, Biomedical Center, Protein Analysis Unit, Ludwig-Maximilians-Universität München, Planegg, Germany
| | - Axel Imhof
- Faculty of Medicine, Biomedical Center, Protein Analysis Unit, Ludwig-Maximilians-Universität München, Planegg, Germany
| | - Robin Andersson
- Section for Computational and RNA Biology, Department of Biology, University of Copenhagen, Copenhagen, Denmark.
- The Novo Nordisk Foundation Center for Genomic Mechanisms of Disease, Broad Institute of MIT and Harvard, Cambridge, MA, USA.
| | - Joshua M Brickman
- Novo Nordisk Foundation Center for Stem Cell Medicine (reNEW), University of Copenhagen, Copenhagen, Denmark.
| | - Anja Groth
- Novo Nordisk Foundation Center for Protein Research (CPR), University of Copenhagen, Copenhagen, Denmark.
- Biotech Research and Innovation Centre (BRIC), University of Copenhagen, Copenhagen, Denmark.
- Department of Cellular and Molecular Medicine (ICMM), University of Copenhagen, Copenhagen, Denmark.
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15
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Glancy E, Wang C, Tuck E, Healy E, Amato S, Neikes HK, Mariani A, Mucha M, Vermeulen M, Pasini D, Bracken AP. PRC2.1- and PRC2.2-specific accessory proteins drive recruitment of different forms of canonical PRC1. Mol Cell 2023; 83:1393-1411.e7. [PMID: 37030288 PMCID: PMC10168607 DOI: 10.1016/j.molcel.2023.03.018] [Citation(s) in RCA: 16] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2022] [Revised: 01/19/2023] [Accepted: 03/16/2023] [Indexed: 04/10/2023]
Abstract
Polycomb repressive complex 2 (PRC2) mediates H3K27me3 deposition, which is thought to recruit canonical PRC1 (cPRC1) via chromodomain-containing CBX proteins to promote stable repression of developmental genes. PRC2 forms two major subcomplexes, PRC2.1 and PRC2.2, but their specific roles remain unclear. Through genetic knockout (KO) and replacement of PRC2 subcomplex-specific subunits in naïve and primed pluripotent cells, we uncover distinct roles for PRC2.1 and PRC2.2 in mediating the recruitment of different forms of cPRC1. PRC2.1 catalyzes the majority of H3K27me3 at Polycomb target genes and is sufficient to promote recruitment of CBX2/4-cPRC1 but not CBX7-cPRC1. Conversely, while PRC2.2 is poor at catalyzing H3K27me3, we find that its accessory protein JARID2 is essential for recruitment of CBX7-cPRC1 and the consequent 3D chromatin interactions at Polycomb target genes. We therefore define distinct contributions of PRC2.1- and PRC2.2-specific accessory proteins to Polycomb-mediated repression and uncover a new mechanism for cPRC1 recruitment.
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Affiliation(s)
- Eleanor Glancy
- Smurfit Institute of Genetics, Trinity College Dublin, Dublin 2, Ireland
| | - Cheng Wang
- Smurfit Institute of Genetics, Trinity College Dublin, Dublin 2, Ireland
| | - Ellen Tuck
- Smurfit Institute of Genetics, Trinity College Dublin, Dublin 2, Ireland
| | - Evan Healy
- Smurfit Institute of Genetics, Trinity College Dublin, Dublin 2, Ireland
| | - Simona Amato
- Department of Experimental Oncology, IEO, European Institute of Oncology IRCCS, Via Adamello 16, 20139 Milan, Italy
| | - Hannah K Neikes
- Department of Molecular Biology, Faculty of Science, Radboud Institute for Molecular Life Sciences, Oncode Institute, Radboud University Nijmegen, 6525 GA Nijmegen, the Netherlands
| | - Andrea Mariani
- Department of Experimental Oncology, IEO, European Institute of Oncology IRCCS, Via Adamello 16, 20139 Milan, Italy
| | - Marlena Mucha
- Smurfit Institute of Genetics, Trinity College Dublin, Dublin 2, Ireland
| | - Michiel Vermeulen
- Department of Molecular Biology, Faculty of Science, Radboud Institute for Molecular Life Sciences, Oncode Institute, Radboud University Nijmegen, 6525 GA Nijmegen, the Netherlands; The Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - Diego Pasini
- Department of Experimental Oncology, IEO, European Institute of Oncology IRCCS, Via Adamello 16, 20139 Milan, Italy; Department of Health Sciences, University of Milan, Via A. di Rudini 8, 20142 Milan, Italy
| | - Adrian P Bracken
- Smurfit Institute of Genetics, Trinity College Dublin, Dublin 2, Ireland.
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16
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Salzler HR, Vandadi V, McMichael BD, Brown JC, Boerma SA, Leatham-Jensen MP, Adams KM, Meers MP, Simon JM, Duronio RJ, McKay DJ, Matera AG. Distinct roles for canonical and variant histone H3 lysine-36 in Polycomb silencing. SCIENCE ADVANCES 2023; 9:eadf2451. [PMID: 36857457 PMCID: PMC9977188 DOI: 10.1126/sciadv.adf2451] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Accepted: 01/31/2023] [Indexed: 05/26/2023]
Abstract
Polycomb complexes regulate cell type-specific gene expression programs through heritable silencing of target genes. Trimethylation of histone H3 lysine 27 (H3K27me3) is essential for this process. Perturbation of H3K36 is thought to interfere with H3K27me3. We show that mutants of Drosophila replication-dependent (H3.2K36R) or replication-independent (H3.3K36R) histone H3 genes generally maintain Polycomb silencing and reach later stages of development. In contrast, combined (H3.3K36RH3.2K36R) mutants display widespread Hox gene misexpression and fail to develop past the first larval stage. Chromatin profiling revealed that the H3.2K36R mutation disrupts H3K27me3 levels broadly throughout silenced domains, whereas these regions are mostly unaffected in H3.3K36R animals. Analysis of H3.3 distributions showed that this histone is enriched at presumptive Polycomb response elements located outside of silenced domains but relatively depleted from those inside. We conclude that H3.2 and H3.3 K36 residues collaborate to repress Hox genes using different mechanisms.
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Affiliation(s)
- Harmony R. Salzler
- Integrative Program for Biological and Genome Sciences, University of North Carolina, Chapel Hill, NC, USA
| | - Vasudha Vandadi
- Integrative Program for Biological and Genome Sciences, University of North Carolina, Chapel Hill, NC, USA
| | - Benjamin D. McMichael
- Integrative Program for Biological and Genome Sciences, University of North Carolina, Chapel Hill, NC, USA
- Department of Biology, University of North Carolina, Chapel Hill, NC, USA
| | - John C. Brown
- Integrative Program for Biological and Genome Sciences, University of North Carolina, Chapel Hill, NC, USA
| | - Sally A. Boerma
- Department of Biology, Carleton College, Northfield, MN, USA
| | - Mary P. Leatham-Jensen
- Integrative Program for Biological and Genome Sciences, University of North Carolina, Chapel Hill, NC, USA
| | - Kirsten M. Adams
- Department of Biology, University of North Carolina, Chapel Hill, NC, USA
| | - Michael P. Meers
- Integrative Program for Biological and Genome Sciences, University of North Carolina, Chapel Hill, NC, USA
- Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, NC, USA
| | - Jeremy M. Simon
- Department of Genetics, University of North Carolina, Chapel Hill, NC, USA
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC, USA
| | - Robert J. Duronio
- Integrative Program for Biological and Genome Sciences, University of North Carolina, Chapel Hill, NC, USA
- Department of Biology, University of North Carolina, Chapel Hill, NC, USA
- Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, NC, USA
- Department of Genetics, University of North Carolina, Chapel Hill, NC, USA
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC, USA
| | - Daniel J. McKay
- Integrative Program for Biological and Genome Sciences, University of North Carolina, Chapel Hill, NC, USA
- Department of Biology, University of North Carolina, Chapel Hill, NC, USA
- Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, NC, USA
- Department of Genetics, University of North Carolina, Chapel Hill, NC, USA
| | - A. Gregory Matera
- Integrative Program for Biological and Genome Sciences, University of North Carolina, Chapel Hill, NC, USA
- Department of Biology, University of North Carolina, Chapel Hill, NC, USA
- Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, NC, USA
- Department of Genetics, University of North Carolina, Chapel Hill, NC, USA
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC, USA
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17
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H2A Ubiquitination Alters H3-tail Dynamics on Linker-DNA to Enhance H3K27 Methylation. J Mol Biol 2023; 435:167936. [PMID: 36610636 DOI: 10.1016/j.jmb.2022.167936] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Revised: 12/15/2022] [Accepted: 12/22/2022] [Indexed: 01/06/2023]
Abstract
Polycomb repressive complex 1 (PRC1) and PRC2 are responsible for epigenetic gene regulation. PRC1 ubiquitinates histone H2A (H2Aub), which subsequently promotes PRC2 to introduce the H3 lysine 27 tri-methyl (H3K27me3) repressive chromatin mark. Although this mechanism provides a link between the two key transcriptional repressors, PRC1 and PRC2, it is unknown how histone-tail dynamics contribute to this process. Here, we have examined the effect of H2A ubiquitination and linker-DNA on H3-tail dynamics and H3K27 methylation by PRC2. In naïve nucleosomes, the H3-tail dynamically contacts linker DNA in addition to core DNA, and the linker-DNA is as important for H3K27 methylation as H2A ubiquitination. H2A ubiquitination alters contacts between the H3-tail and DNA to improve the methyltransferase activity of the PRC2-AEBP2-JARID2 complex. Collectively, our data support a model in which H2A ubiquitination by PRC1 synergizes with linker-DNA to hold H3 histone tails poised for their methylation by PRC2-AEBP2-JARID2.
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18
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Fu MP, Merrill SM, Sharma M, Gibson WT, Turvey SE, Kobor MS. Rare diseases of epigenetic origin: Challenges and opportunities. Front Genet 2023; 14:1113086. [PMID: 36814905 PMCID: PMC9939656 DOI: 10.3389/fgene.2023.1113086] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Accepted: 01/24/2023] [Indexed: 02/09/2023] Open
Abstract
Rare diseases (RDs), more than 80% of which have a genetic origin, collectively affect approximately 350 million people worldwide. Progress in next-generation sequencing technology has both greatly accelerated the pace of discovery of novel RDs and provided more accurate means for their diagnosis. RDs that are driven by altered epigenetic regulation with an underlying genetic basis are referred to as rare diseases of epigenetic origin (RDEOs). These diseases pose unique challenges in research, as they often show complex genetic and clinical heterogeneity arising from unknown gene-disease mechanisms. Furthermore, multiple other factors, including cell type and developmental time point, can confound attempts to deconvolute the pathophysiology of these disorders. These challenges are further exacerbated by factors that contribute to epigenetic variability and the difficulty of collecting sufficient participant numbers in human studies. However, new molecular and bioinformatics techniques will provide insight into how these disorders manifest over time. This review highlights recent studies addressing these challenges with innovative solutions. Further research will elucidate the mechanisms of action underlying unique RDEOs and facilitate the discovery of treatments and diagnostic biomarkers for screening, thereby improving health trajectories and clinical outcomes of affected patients.
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Affiliation(s)
- Maggie P. Fu
- Department of Medical Genetics, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada,Centre for Molecular Medicine and Therapeutics, University of British Columbia, Vancouver, BC, Canada,BC Children’s Hospital Research Institute, Vancouver, BC, Canada
| | - Sarah M. Merrill
- Department of Medical Genetics, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada,Centre for Molecular Medicine and Therapeutics, University of British Columbia, Vancouver, BC, Canada,BC Children’s Hospital Research Institute, Vancouver, BC, Canada
| | - Mehul Sharma
- BC Children’s Hospital Research Institute, Vancouver, BC, Canada,Department of Pediatrics, Faculty of Medicine, BC Children’s Hospital, University of British Columbia, Vancouver, BC, Canada
| | - William T. Gibson
- Department of Medical Genetics, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada,BC Children’s Hospital Research Institute, Vancouver, BC, Canada
| | - Stuart E. Turvey
- BC Children’s Hospital Research Institute, Vancouver, BC, Canada,Department of Pediatrics, Faculty of Medicine, BC Children’s Hospital, University of British Columbia, Vancouver, BC, Canada
| | - Michael S. Kobor
- Department of Medical Genetics, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada,Centre for Molecular Medicine and Therapeutics, University of British Columbia, Vancouver, BC, Canada,BC Children’s Hospital Research Institute, Vancouver, BC, Canada,*Correspondence: Michael S. Kobor,
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19
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Guo Y, Yu Y, Wang GG. Polycomb Repressive Complex 2 in Oncology. Cancer Treat Res 2023; 190:273-320. [PMID: 38113005 DOI: 10.1007/978-3-031-45654-1_9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2023]
Abstract
Dynamic regulation of the chromatin state by Polycomb Repressive Complex 2 (PRC2) provides an important mean for epigenetic gene control that can profoundly influence normal development and cell lineage specification. PRC2 and PRC2-induced methylation of histone H3 lysine 27 (H3K27) are critically involved in a wide range of DNA-templated processes, which at least include transcriptional repression and gene imprinting, organization of three-dimensional chromatin structure, DNA replication and DNA damage response and repair. PRC2-based genome regulation often goes wrong in diseases, notably cancer. This chapter discusses about different modes-of-action through which PRC2 and EZH2, a catalytic subunit of PRC2, mediate (epi)genomic and transcriptomic regulation. We will also discuss about how alteration or mutation of the PRC2 core or axillary component promotes oncogenesis, how post-translational modification regulates functionality of EZH2 and PRC2, and how PRC2 and other epigenetic pathways crosstalk. Lastly, we will briefly touch on advances in targeting EZH2 and PRC2 dependence as cancer therapeutics.
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Affiliation(s)
- Yiran Guo
- Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, NC, 27710, USA.
- Duke Cancer Institute, Duke University School of Medicine, Durham, NC, 27710, USA.
| | - Yao Yu
- Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, NC, 27710, USA
- Duke Cancer Institute, Duke University School of Medicine, Durham, NC, 27710, USA
| | - Gang Greg Wang
- Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, NC, 27710, USA.
- Duke Cancer Institute, Duke University School of Medicine, Durham, NC, 27710, USA.
- Department of Pathology, Duke University School of Medicine, Durham, NC, 27710, USA.
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20
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Regulation, functions and transmission of bivalent chromatin during mammalian development. Nat Rev Mol Cell Biol 2023; 24:6-26. [PMID: 36028557 DOI: 10.1038/s41580-022-00518-2] [Citation(s) in RCA: 55] [Impact Index Per Article: 55.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/05/2022] [Indexed: 12/25/2022]
Abstract
Cells differentiate and progress through development guided by a dynamic chromatin landscape that mediates gene expression programmes. During development, mammalian cells display a paradoxical chromatin state: histone modifications associated with gene activation (trimethylated histone H3 Lys4 (H3K4me3)) and with gene repression (trimethylated H3 Lys27 (H3K27me3)) co-occur at promoters of developmental genes. This bivalent chromatin modification state is thought to poise important regulatory genes for expression or repression during cell-lineage specification. In this Review, we discuss recent work that has expanded our understanding of the molecular basis of bivalent chromatin and its contributions to mammalian development. We describe the factors that establish bivalency, especially histone-lysine N-methyltransferase 2B (KMT2B) and Polycomb repressive complex 2 (PRC2), and consider evidence indicating that PRC1 shapes bivalency and may contribute to its transmission between generations. We posit that bivalency is a key feature of germline and embryonic stem cells, as well as other types of stem and progenitor cells. Finally, we discuss the relevance of bivalent chromtin to human development and cancer, and outline avenues of future research.
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21
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Zhang H, Liu Y, Xie Y, Zhu Y, Liu J, Lu F. H3K27me3 shapes DNA methylome by inhibiting UHRF1-mediated H3 ubiquitination. SCIENCE CHINA. LIFE SCIENCES 2022; 65:1685-1700. [PMID: 35831553 DOI: 10.1007/s11427-022-2155-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Accepted: 06/27/2022] [Indexed: 06/15/2023]
Abstract
DNA methylation and histone lysine tri-methylation at H3K27 (H3K27me3) are two chromatin modifications for transcriptional gene silencing, which play important roles in diverse biological processes, including cell fate determination and cell lineage commitment. These two marks are largely mutually exclusive and target distinct sets of genes in the mammalian genome. However, how H3K27me3 shapes the DNA methylome remains elusive. Here, we report that the loss of H3K27me3 modification leads to increased DNA methylation at previously marked H3K27me3 sites, indicating that H3K27me3 negatively regulates DNA methylation. Genome-wide analysis of H3 ubiquitination, essential for recruitment and activation of DNA methyltransferase DNMT1, reveals the absence of H3 ubiquitination at H3K27me3 marked nucleosomes. Moreover, loss of H3K27me3 modification induces an increase in H3K18 ubiquitination at the corresponding hyper-methylated loci. Importantly, we show that H3K27me3 directly inhibits UHRF1-mediated H3 ubiquitination toward nucleosomes in a defined biochemical assay. Taken together, our findings reveal a general mechanism for H3K27me3-mediated shaping of the mammalian DNA methylome via modulation of H3 ubiquitination.
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Affiliation(s)
- Honglian Zhang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing, 100101, China
| | - Ying Liu
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing, 100101, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yali Xie
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing, 100101, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yunji Zhu
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing, 100101, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Jingwen Liu
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing, 100101, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Falong Lu
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing, 100101, China.
- University of Chinese Academy of Sciences, Beijing, 100049, China.
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22
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Doyle EJ, Morey L, Conway E. Know when to fold 'em: Polycomb complexes in oncogenic 3D genome regulation. Front Cell Dev Biol 2022; 10:986319. [PMID: 36105358 PMCID: PMC9464936 DOI: 10.3389/fcell.2022.986319] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Accepted: 08/04/2022] [Indexed: 11/13/2022] Open
Abstract
Chromatin is spatially and temporally regulated through a series of orchestrated processes resulting in the formation of 3D chromatin structures such as topologically associating domains (TADs), loops and Polycomb Bodies. These structures are closely linked to transcriptional regulation, with loss of control of these processes a frequent feature of cancer and developmental syndromes. One such oncogenic disruption of the 3D genome is through recurrent dysregulation of Polycomb Group Complex (PcG) functions either through genetic mutations, amplification or deletion of genes that encode for PcG proteins. PcG complexes are evolutionarily conserved epigenetic complexes. They are key for early development and are essential transcriptional repressors. PcG complexes include PRC1, PRC2 and PR-DUB which are responsible for the control of the histone modifications H2AK119ub1 and H3K27me3. The spatial distribution of the complexes within the nuclear environment, and their associated modifications have profound effects on the regulation of gene transcription and the 3D genome. Nevertheless, how PcG complexes regulate 3D chromatin organization is still poorly understood. Here we glean insights into the role of PcG complexes in 3D genome regulation and compaction, how these processes go awry during tumorigenesis and the therapeutic implications that result from our insights into these mechanisms.
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Affiliation(s)
- Emma J. Doyle
- School of Biomolecular and Biomedical Science, Conway Institute, University College Dublin, Dublin, Ireland
| | - Lluis Morey
- Sylvester Comprehensive Cancer Centre, Miami, FL, United States
- Department of Human Genetics, Biomedical Research Building, University of Miami Miller School of Medicine, Miami, FL, United States
| | - Eric Conway
- School of Biomolecular and Biomedical Science, Conway Institute, University College Dublin, Dublin, Ireland
- Smurfit Institute of Genetics, Trinity College Dublin, Dublin, Ireland
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23
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Critical Roles of Polycomb Repressive Complexes in Transcription and Cancer. Int J Mol Sci 2022; 23:ijms23179574. [PMID: 36076977 PMCID: PMC9455514 DOI: 10.3390/ijms23179574] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2022] [Revised: 08/16/2022] [Accepted: 08/18/2022] [Indexed: 11/17/2022] Open
Abstract
Polycomp group (PcG) proteins are members of highly conserved multiprotein complexes, recognized as gene transcriptional repressors during development and shown to play a role in various physiological and pathological processes. PcG proteins consist of two Polycomb repressive complexes (PRCs) with different enzymatic activities: Polycomb repressive complexes 1 (PRC1), a ubiquitin ligase, and Polycomb repressive complexes 2 (PRC2), a histone methyltransferase. Traditionally, PRCs have been described to be associated with transcriptional repression of homeotic genes, as well as gene transcription activating effects. Particularly in cancer, PRCs have been found to misregulate gene expression, not only depending on the function of the whole PRCs, but also through their separate subunits. In this review, we focused especially on the recent findings in the transcriptional regulation of PRCs, the oncogenic and tumor-suppressive roles of PcG proteins, and the research progress of inhibitors targeting PRCs.
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Hernández-Romero IA, Valdes VJ. De Novo Polycomb Recruitment and Repressive Domain Formation. EPIGENOMES 2022; 6:25. [PMID: 35997371 PMCID: PMC9397058 DOI: 10.3390/epigenomes6030025] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Revised: 08/15/2022] [Accepted: 08/18/2022] [Indexed: 11/29/2022] Open
Abstract
Every cell of an organism shares the same genome; even so, each cellular lineage owns a different transcriptome and proteome. The Polycomb group proteins (PcG) are essential regulators of gene repression patterning during development and homeostasis. However, it is unknown how the repressive complexes, PRC1 and PRC2, identify their targets and elicit new Polycomb domains during cell differentiation. Classical recruitment models consider the pre-existence of repressive histone marks; still, de novo target binding overcomes the absence of both H3K27me3 and H2AK119ub. The CpG islands (CGIs), non-core proteins, and RNA molecules are involved in Polycomb recruitment. Nonetheless, it is unclear how de novo targets are identified depending on the physiological context and developmental stage and which are the leading players stabilizing Polycomb complexes at domain nucleation sites. Here, we examine the features of de novo sites and the accessory elements bridging its recruitment and discuss the first steps of Polycomb domain formation and transcriptional regulation, comprehended by the experimental reconstruction of the repressive domains through time-resolved genomic analyses in mammals.
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Affiliation(s)
| | - Victor Julian Valdes
- Department of Cell Biology and Development, Institute of Cellular Physiology (IFC), National Autonomous University of Mexico (UNAM), Mexico City 04510, Mexico
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25
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Liu X, Liu X. PRC2, Chromatin Regulation, and Human Disease: Insights From Molecular Structure and Function. Front Oncol 2022; 12:894585. [PMID: 35800061 PMCID: PMC9255955 DOI: 10.3389/fonc.2022.894585] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Accepted: 05/17/2022] [Indexed: 01/25/2023] Open
Abstract
Polycomb repressive complex 2 (PRC2) is a multisubunit histone-modifying enzyme complex that mediates methylation of histone H3 lysine 27 (H3K27). Trimethylated H3K27 (H3K27me3) is an epigenetic hallmark of gene silencing. PRC2 plays a crucial role in a plethora of fundamental biological processes, and PRC2 dysregulation has been repeatedly implicated in cancers and developmental disorders. Here, we review the current knowledge on mechanisms of cellular regulation of PRC2 function, particularly regarding H3K27 methylation and chromatin targeting. PRC2-related disease mechanisms are also discussed. The mode of action of PRC2 in gene regulation is summarized, which includes competition between H3K27 methylation and acetylation, crosstalk with transcription machinery, and formation of high-order chromatin structure. Recent progress in the structural biology of PRC2 is highlighted from the aspects of complex assembly, enzyme catalysis, and chromatin recruitment, which together provide valuable insights into PRC2 function in close-to-atomic detail. Future studies on the molecular function and structure of PRC2 in the context of native chromatin and in the presence of other regulators like RNAs will continue to deepen our understanding of the stability and plasticity of developmental transcriptional programs broadly impacted by PRC2.
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26
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Sudarshan D, Avvakumov N, Lalonde ME, Alerasool N, Joly-Beauparlant C, Jacquet K, Mameri A, Lambert JP, Rousseau J, Lachance C, Paquet E, Herrmann L, Thonta Setty S, Loehr J, Bernardini MQ, Rouzbahman M, Gingras AC, Coulombe B, Droit A, Taipale M, Doyon Y, Côté J. Recurrent chromosomal translocations in sarcomas create a megacomplex that mislocalizes NuA4/TIP60 to Polycomb target loci. Genes Dev 2022; 36:664-683. [PMID: 35710139 DOI: 10.1101/gad.348982.121] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Accepted: 05/31/2022] [Indexed: 11/25/2022]
Abstract
Chromosomal translocations frequently promote carcinogenesis by producing gain-of-function fusion proteins. Recent studies have identified highly recurrent chromosomal translocations in patients with endometrial stromal sarcomas (ESSs) and ossifying fibromyxoid tumors (OFMTs), leading to an in-frame fusion of PHF1 (PCL1) to six different subunits of the NuA4/TIP60 complex. While NuA4/TIP60 is a coactivator that acetylates chromatin and loads the H2A.Z histone variant, PHF1 is part of the Polycomb repressive complex 2 (PRC2) linked to transcriptional repression of key developmental genes through methylation of histone H3 on lysine 27. In this study, we characterize the fusion protein produced by the EPC1-PHF1 translocation. The chimeric protein assembles a megacomplex harboring both NuA4/TIP60 and PRC2 activities and leads to mislocalization of chromatin marks in the genome, in particular over an entire topologically associating domain including part of the HOXD cluster. This is linked to aberrant gene expression-most notably increased expression of PRC2 target genes. Furthermore, we show that JAZF1-implicated with a PRC2 component in the most frequent translocation in ESSs, JAZF1-SUZ12-is a potent transcription activator that physically associates with NuA4/TIP60, its fusion creating outcomes similar to those of EPC1-PHF1 Importantly, the specific increased expression of PRC2 targets/HOX genes was also confirmed with ESS patient samples. Altogether, these results indicate that most chromosomal translocations linked to these sarcomas use the same molecular oncogenic mechanism through a physical merge of NuA4/TIP60 and PRC2 complexes, leading to mislocalization of histone marks and aberrant Polycomb target gene expression.
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Affiliation(s)
- Deepthi Sudarshan
- Centre Hospitalier Universitaire (CHU) de Québec-Université Laval Research Center, Laval University Cancer Research Center, Quebec City, Quebec G1R 3S3, Canada
| | - Nikita Avvakumov
- Centre Hospitalier Universitaire (CHU) de Québec-Université Laval Research Center, Laval University Cancer Research Center, Quebec City, Quebec G1R 3S3, Canada
| | - Marie-Eve Lalonde
- Centre Hospitalier Universitaire (CHU) de Québec-Université Laval Research Center, Laval University Cancer Research Center, Quebec City, Quebec G1R 3S3, Canada
| | - Nader Alerasool
- Donnelly Centre for Cellular and Biomolecular Research, Department of Molecular Genetics, University of Toronto, Toronto, Ontario M5S 3E1, Canada
| | - Charles Joly-Beauparlant
- Computational Biology Laboratory, CHU de Québec-Université Laval Research Center, Quebec City, Quebec G1V 4G2, Canada
| | - Karine Jacquet
- Centre Hospitalier Universitaire (CHU) de Québec-Université Laval Research Center, Laval University Cancer Research Center, Quebec City, Quebec G1R 3S3, Canada
| | - Amel Mameri
- Centre Hospitalier Universitaire (CHU) de Québec-Université Laval Research Center, Laval University Cancer Research Center, Quebec City, Quebec G1R 3S3, Canada
| | - Jean-Philippe Lambert
- Centre Hospitalier Universitaire (CHU) de Québec-Université Laval Research Center, Laval University Cancer Research Center, Quebec City, Quebec G1R 3S3, Canada.,Centre for Systems Biology, Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario M5G 1X5, Canada
| | - Justine Rousseau
- Institut de Recherches Cliniques de Montréal, Department of Biochemistry and Molecular Medicine, Université de Montréal, Montreal, Quebec H3T 1J4, Canada
| | - Catherine Lachance
- Centre Hospitalier Universitaire (CHU) de Québec-Université Laval Research Center, Laval University Cancer Research Center, Quebec City, Quebec G1R 3S3, Canada
| | - Eric Paquet
- Centre Hospitalier Universitaire (CHU) de Québec-Université Laval Research Center, Laval University Cancer Research Center, Quebec City, Quebec G1R 3S3, Canada
| | - Lara Herrmann
- Computational Biology Laboratory, CHU de Québec-Université Laval Research Center, Quebec City, Quebec G1V 4G2, Canada
| | - Samarth Thonta Setty
- Computational Biology Laboratory, CHU de Québec-Université Laval Research Center, Quebec City, Quebec G1V 4G2, Canada
| | - Jeremy Loehr
- Centre Hospitalier Universitaire (CHU) de Québec-Université Laval Research Center, Laval University Cancer Research Center, Quebec City, Quebec G1R 3S3, Canada
| | - Marcus Q Bernardini
- Department of Gynecologic Oncology, Princess Margaret Cancer Center, University Health Network, Sinai Health System, Toronto, Ontario M5B 2M9, Canada.,Department of Obstetrics and Gynecology, University of Toronto, Toronto, Ontario M5G 1X8, Canada
| | - Marjan Rouzbahman
- Department of Laboratory Medicine and Pathobiology, Princess Margaret Hospital Cancer Centre, Toronto, Ontario M5G 2C4, Canada
| | - Anne-Claude Gingras
- Centre for Systems Biology, Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario M5G 1X5, Canada
| | - Benoit Coulombe
- Institut de Recherches Cliniques de Montréal, Department of Biochemistry and Molecular Medicine, Université de Montréal, Montreal, Quebec H3T 1J4, Canada
| | - Arnaud Droit
- Computational Biology Laboratory, CHU de Québec-Université Laval Research Center, Quebec City, Quebec G1V 4G2, Canada
| | - Mikko Taipale
- Donnelly Centre for Cellular and Biomolecular Research, Department of Molecular Genetics, University of Toronto, Toronto, Ontario M5S 3E1, Canada
| | - Yannick Doyon
- Centre Hospitalier Universitaire (CHU) de Québec-Université Laval Research Center, Laval University Cancer Research Center, Quebec City, Quebec G1R 3S3, Canada
| | - Jacques Côté
- Centre Hospitalier Universitaire (CHU) de Québec-Université Laval Research Center, Laval University Cancer Research Center, Quebec City, Quebec G1R 3S3, Canada
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27
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Owen BM, Davidovich C. DNA binding by polycomb-group proteins: searching for the link to CpG islands. Nucleic Acids Res 2022; 50:4813-4839. [PMID: 35489059 PMCID: PMC9122586 DOI: 10.1093/nar/gkac290] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Revised: 03/25/2022] [Accepted: 04/25/2022] [Indexed: 11/13/2022] Open
Abstract
Polycomb group proteins predominantly exist in polycomb repressive complexes (PRCs) that cooperate to maintain the repressed state of thousands of cell-type-specific genes. Targeting PRCs to the correct sites in chromatin is essential for their function. However, the mechanisms by which PRCs are recruited to their target genes in mammals are multifactorial and complex. Here we review DNA binding by polycomb group proteins. There is strong evidence that the DNA-binding subunits of PRCs and their DNA-binding activities are required for chromatin binding and CpG targeting in cells. In vitro, CpG-specific binding was observed for truncated proteins externally to the context of their PRCs. Yet, the mere DNA sequence cannot fully explain the subset of CpG islands that are targeted by PRCs in any given cell type. At this time we find very little structural and biophysical evidence to support a model where sequence-specific DNA-binding activity is required or sufficient for the targeting of CpG-dinucleotide sequences by polycomb group proteins while they are within the context of their respective PRCs, either PRC1 or PRC2. We discuss the current knowledge and open questions on how the DNA-binding activities of polycomb group proteins facilitate the targeting of PRCs to chromatin.
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Affiliation(s)
- Brady M Owen
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, VIC, Australia
| | - Chen Davidovich
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, VIC, Australia.,EMBL-Australia, Clayton, VIC, Australia
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28
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Fischer S, Weber LM, Liefke R. Evolutionary adaptation of the Polycomb repressive complex 2. Epigenetics Chromatin 2022; 15:7. [PMID: 35193659 PMCID: PMC8864842 DOI: 10.1186/s13072-022-00439-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2021] [Accepted: 02/08/2022] [Indexed: 12/31/2022] Open
Abstract
The Polycomb repressive complex 2 (PRC2) is an essential chromatin regulatory complex involved in repressing the transcription of diverse developmental genes. PRC2 consists of a core complex; possessing H3K27 methyltransferase activity and various associated factors that are important to modulate its function. During evolution, the composition of PRC2 and the functionality of PRC2 components have changed considerably. Here, we compare the PRC2 complex members of Drosophila and mammals and describe their adaptation to altered biological needs. We also highlight how the PRC2.1 subcomplex has gained multiple novel functions and discuss the implications of these changes for the function of PRC2 in chromatin regulation.
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Affiliation(s)
- Sabrina Fischer
- Institute of Molecular Biology and Tumor Research (IMT), Philipps University of Marburg, 35043, Marburg, Germany
| | - Lisa Marie Weber
- Institute of Molecular Biology and Tumor Research (IMT), Philipps University of Marburg, 35043, Marburg, Germany
| | - Robert Liefke
- Institute of Molecular Biology and Tumor Research (IMT), Philipps University of Marburg, 35043, Marburg, Germany. .,Department of Hematology, Oncology, and Immunology, University Hospital Giessen and Marburg, 35043, Marburg, Germany.
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29
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Erlendson AA, Freitag M. Not all Is SET for Methylation: Evolution of Eukaryotic Protein Methyltransferases. Methods Mol Biol 2022; 2529:3-40. [PMID: 35733008 DOI: 10.1007/978-1-0716-2481-4_1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Dynamic posttranslational modifications to canonical histones that constitute the nucleosome (H2A, H2B, H3, and H4) control all aspects of enzymatic transactions with DNA. Histone methylation has been studied heavily for the past 20 years, and our mechanistic understanding of the control and function of individual methylation events on specific histone arginine and lysine residues has been greatly improved over the past decade, driven by excellent new tools and methods. Here, we will summarize what is known about the distribution and some of the functions of protein methyltransferases from all major eukaryotic supergroups. The main conclusion is that protein, and specifically histone, methylation is an ancient process. Many taxa in all supergroups have lost some subfamilies of both protein arginine methyltransferases (PRMT) and the heavily studied SET domain lysine methyltransferases (KMT). Over time, novel subfamilies, especially of SET domain proteins, arose. We use the interactions between H3K27 and H3K36 methylation as one example for the complex circuitry of histone modifications that make up the "histone code," and we discuss one recent example (Paramecium Ezl1) for how extant enzymes that may resemble more ancient SET domain KMTs are able to modify two lysine residues that have divergent functions in plants, fungi, and animals. Complexity of SET domain KMT function in the well-studied plant and animal lineages arose not only by gene duplication but also acquisition of novel DNA- and histone-binding domains in certain subfamilies.
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Affiliation(s)
- Allyson A Erlendson
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, OR, USA
| | - Michael Freitag
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, OR, USA.
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30
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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.
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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
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31
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Abstract
To predict transcription, one needs a mechanistic understanding of how the numerous required transcription factors (TFs) explore the nuclear space to find their target genes, assemble, cooperate, and compete with one another. Advances in fluorescence microscopy have made it possible to visualize real-time TF dynamics in living cells, leading to two intriguing observations: first, most TFs contact chromatin only transiently; and second, TFs can assemble into clusters through their intrinsically disordered regions. These findings suggest that highly dynamic events and spatially structured nuclear microenvironments might play key roles in transcription regulation that are not yet fully understood. The emerging model is that while some promoters directly convert TF-binding events into on/off cycles of transcription, many others apply complex regulatory layers that ultimately lead to diverse phenotypic outputs. Cracking this kinetic code is an ongoing and challenging task that is made possible by combining innovative imaging approaches with biophysical models.
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Affiliation(s)
- Feiyue Lu
- Institute for Systems Genetics and Cell Biology Department, NYU School of Medicine, New York, New York 10016, USA
| | - Timothée Lionnet
- Institute for Systems Genetics and Cell Biology Department, NYU School of Medicine, New York, New York 10016, USA
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32
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Bieluszewski T, Xiao J, Yang Y, Wagner D. PRC2 activity, recruitment, and silencing: a comparative perspective. TRENDS IN PLANT SCIENCE 2021; 26:1186-1198. [PMID: 34294542 DOI: 10.1016/j.tplants.2021.06.006] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Revised: 06/08/2021] [Accepted: 06/16/2021] [Indexed: 05/22/2023]
Abstract
Polycomb repressive complex (PRC)-mediated gene silencing is vital for cell identity and development in both the plant and the animal kingdoms. It also modulates responses to stress. Two major protein complexes, PRC1 and PRC2, execute conserved nuclear functions in metazoans and plants through covalent modification of histones and by compacting chromatin. While a general requirement for Polycomb complexes in mitotically heritable gene repression in the context of chromatin is well established, recent studies have brought new insights into the regulation of Polycomb complex activity and recruitment. Here, we discuss these recent advances with emphasis on PRC2.
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Affiliation(s)
- Tomasz Bieluszewski
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19103, USA
| | - Jun Xiao
- State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing 100101, China; Centre of Excellence for Plant and Microbial Science (CEPAMS), the John Innes Centre, Norwich Research Park, Norwich, NR4 7UH, UK
| | - Yiman Yang
- State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing 100101, China; College of Horticulture, Nanjing Agricultural University, Nanjing, 210095, China
| | - Doris Wagner
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19103, USA.
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33
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Tang G, Yuan J, Wang J, Zhang YZ, Xie SS, Wang H, Tao Z, Liu H, Kistler HC, Zhao Y, Duan CG, Liu W, Ma Z, Chen Y. Fusarium BP1 is a reader of H3K27 methylation. Nucleic Acids Res 2021; 49:10448-10464. [PMID: 34570240 PMCID: PMC8501951 DOI: 10.1093/nar/gkab844] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2020] [Revised: 08/31/2021] [Accepted: 09/10/2021] [Indexed: 12/24/2022] Open
Abstract
Histone H3 lysine 27 methylation catalyzed by polycomb repressive complex 2 (PRC2) is conserved from fungi to humans and represses gene transcription. However, the mechanism for recognition of methylated H3K27 remains unclear, especially in fungi. Here, we found that the bromo-adjacent homology (BAH)-plant homeodomain (PHD) domain containing protein BAH–PHD protein 1 (BP1) is a reader of H3K27 methylation in the cereal fungal pathogen Fusarium graminearum. BP1 interacts with the core PRC2 component Suz12 and directly binds methylated H3K27. BP1 is distributed in a subset of genomic regions marked by H3K27me3 and co-represses gene transcription. The BP1 deletion mutant shows identical phenotypes on mycelial growth and virulence, as well as similar expression profiles of secondary metabolite genes to the strain lacking the H3K27 methyltransferase Kmt6. More importantly, BP1 can directly bind DNA through its PHD finger, which might increase nucleosome residence and subsequently reinforce transcriptional repression in H3K27me3-marked target regions. A phylogenetic analysis showed that BP1 orthologs are mainly conserved in fungi. Overall, our findings provide novel insights into the mechanism by which PRC2 mediates gene repression in fungi, which is distinct from the PRC1-PRC2 system in plants and mammals.
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Affiliation(s)
- Guangfei Tang
- State Key Laboratory of Rice Biology, Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China.,State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Jianlong Yuan
- Shanghai Center for Plant Stress Biology and CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai 201602, China
| | - Jing Wang
- State Key Laboratory of Rice Biology, Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China
| | - Yi-Zhe Zhang
- Shanghai Center for Plant Stress Biology and CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai 201602, China
| | - Si-Si Xie
- Shanghai Center for Plant Stress Biology and CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai 201602, China
| | - Hongkai Wang
- State Key Laboratory of Rice Biology, Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China
| | - Zeng Tao
- State Key Laboratory of Rice Biology, Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China
| | - Huiquan Liu
- State Key Laboratory of Crop Stress Biology for Arid Areas and NWAFU-Purdue Joint Research Center, Northwest A&F University, Yangling 712100, China
| | - H Corby Kistler
- Cereal Disease Laboratory, Agricultural Research Service, United States Department of Agriculture, Saint Paul, MN 55108, USA
| | - Youfu Zhao
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Cheng-Guo Duan
- Shanghai Center for Plant Stress Biology and CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai 201602, China
| | - Wende Liu
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Zhonghua Ma
- State Key Laboratory of Rice Biology, Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China
| | - Yun Chen
- State Key Laboratory of Rice Biology, Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Institute of Biotechnology, Zhejiang University, Hangzhou 310058, China
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34
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Hao A, Wang Y, Stovall DB, Wang Y, Sui G. Emerging Roles of LncRNAs in the EZH2-regulated Oncogenic Network. Int J Biol Sci 2021; 17:3268-3280. [PMID: 34512145 PMCID: PMC8416728 DOI: 10.7150/ijbs.63488] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Accepted: 07/16/2021] [Indexed: 12/15/2022] Open
Abstract
Cancer is a life-threatening disease, but cancer therapies based on epigenetic mechanisms have made great progress. Enhancer of zeste homolog 2 (EZH2) is the key catalytic component of Polycomb repressive complex 2 (PRC2) that mediates the tri-methylation of lysine 27 on histone 3 (H3K27me3), a well-recognized marker of transcriptional repression. Mounting evidence indicates that EZH2 is elevated in various cancers and associates with poor prognosis. In addition, many studies revealed that EZH2 is also involved in transcriptional repression dependent or independent of PRC2. Meanwhile, long non-coding RNAs (lncRNAs) have been reported to regulate numerous and diverse signaling pathways in oncogenesis. In this review, we firstly discuss functional interactions between EZH2 and lncRNAs that determine PRC2-dependent and -independent roles of EZH2. Secondly, we summarize the lncRNAs regulating EZH2 expression at transcription, post-transcription and post-translation levels. Thirdly, we review several oncogenic pathways cooperatively regulated by lncRNAs and EZH2, including the Wnt/β-catenin and p53 pathways. In conclusion, lncRNAs play a key role in the EZH2-regulated oncogenic network with many fertile directions to be explored.
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Affiliation(s)
- Aixin Hao
- Key Laboratory of Saline-alkali Vegetation Ecology Restoration, Ministry of Education, College of Life Science, Northeast Forestry University, Harbin 150040, China
| | - Yunxuan Wang
- Department of Medical Oncology, Harbin Medical University Cancer Hospital, Harbin, 150081, China
| | - Daniel B Stovall
- College of Arts and Sciences, Winthrop University, Rock Hill, SC 29733, the United States
| | - Yu Wang
- Key Laboratory of Saline-alkali Vegetation Ecology Restoration, Ministry of Education, College of Life Science, Northeast Forestry University, Harbin 150040, China
| | - Guangchao Sui
- Key Laboratory of Saline-alkali Vegetation Ecology Restoration, Ministry of Education, College of Life Science, Northeast Forestry University, Harbin 150040, China
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35
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Conway E, Rossi F, Fernandez-Perez D, Ponzo E, Ferrari KJ, Zanotti M, Manganaro D, Rodighiero S, Tamburri S, Pasini D. BAP1 enhances Polycomb repression by counteracting widespread H2AK119ub1 deposition and chromatin condensation. Mol Cell 2021; 81:3526-3541.e8. [PMID: 34186021 PMCID: PMC8428331 DOI: 10.1016/j.molcel.2021.06.020] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Revised: 06/17/2021] [Accepted: 06/18/2021] [Indexed: 12/15/2022]
Abstract
BAP1 is mutated or deleted in many cancer types, including mesothelioma, uveal melanoma, and cholangiocarcinoma. It is the catalytic subunit of the PR-DUB complex, which removes PRC1-mediated H2AK119ub1, essential for maintaining transcriptional repression. However, the precise relationship between BAP1 and Polycombs remains elusive. Using embryonic stem cells, we show that BAP1 restricts H2AK119ub1 deposition to Polycomb target sites. This increases the stability of Polycomb with their targets and prevents diffuse accumulation of H2AK119ub1 and H3K27me3. Loss of BAP1 results in a broad increase in H2AK119ub1 levels that is primarily dependent on PCGF3/5-PRC1 complexes. This titrates PRC2 away from its targets and stimulates H3K27me3 accumulation across the genome, leading to a general chromatin compaction. This provides evidence for a unifying model that resolves the apparent contradiction between BAP1 catalytic activity and its role in vivo, uncovering molecular vulnerabilities that could be useful for BAP1-related pathologies.
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Affiliation(s)
- Eric Conway
- IEO, European Institute of Oncology IRCCS, Department of Experimental Oncology, Via Adamello 16, 20139 Milan, Italy
| | - Federico Rossi
- IEO, European Institute of Oncology IRCCS, Department of Experimental Oncology, Via Adamello 16, 20139 Milan, Italy
| | - Daniel Fernandez-Perez
- IEO, European Institute of Oncology IRCCS, Department of Experimental Oncology, Via Adamello 16, 20139 Milan, Italy
| | - Eleonora Ponzo
- IEO, European Institute of Oncology IRCCS, Department of Experimental Oncology, Via Adamello 16, 20139 Milan, Italy
| | - Karin Johanna Ferrari
- IEO, European Institute of Oncology IRCCS, Department of Experimental Oncology, Via Adamello 16, 20139 Milan, Italy
| | - Marika Zanotti
- IEO, European Institute of Oncology IRCCS, Department of Experimental Oncology, Via Adamello 16, 20139 Milan, Italy
| | - Daria Manganaro
- IEO, European Institute of Oncology IRCCS, Department of Experimental Oncology, Via Adamello 16, 20139 Milan, Italy
| | - Simona Rodighiero
- IEO, European Institute of Oncology IRCCS, Department of Experimental Oncology, Via Adamello 16, 20139 Milan, Italy
| | - Simone Tamburri
- IEO, European Institute of Oncology IRCCS, Department of Experimental Oncology, Via Adamello 16, 20139 Milan, Italy; University of Milan, Via A. di Rudini 8, Department of Health Sciences, 20142 Milan, Italy.
| | - Diego Pasini
- IEO, European Institute of Oncology IRCCS, Department of Experimental Oncology, Via Adamello 16, 20139 Milan, Italy; University of Milan, Via A. di Rudini 8, Department of Health Sciences, 20142 Milan, Italy.
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36
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Park SH, Fong KW, Mong E, Martin MC, Schiltz GE, Yu J. Going beyond Polycomb: EZH2 functions in prostate cancer. Oncogene 2021; 40:5788-5798. [PMID: 34349243 PMCID: PMC8487936 DOI: 10.1038/s41388-021-01982-4] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 07/20/2021] [Accepted: 07/22/2021] [Indexed: 02/07/2023]
Abstract
The Polycomb group (PcG) protein Enhancer of Zeste Homolog 2 (EZH2) is one of the three core subunits of the Polycomb Repressive Complex 2 (PRC2). It harbors histone methyltransferase activity (MTase) that specifically catalyze histone 3 lysine 27 (H3K27) methylation on target gene promoters. As such, PRC2 are epigenetic silencers that play important roles in cellular identity and embryonic stem cell maintenance. In the past two decades, mounting evidence supports EZH2 mutations and/or over-expression in a wide array of hematological cancers and solid tumors, including prostate cancer. Further, EZH2 is among the most upregulated genes in neuroendocrine prostate cancers, which become abundant due to the clinical use of high-affinity androgen receptor pathway inhibitors. While numerous studies have reported epigenetic functions of EZH2 that inhibit tumor suppressor genes and promote tumorigenesis, discordance between EZH2 and H3K27 methylation has been reported. Further, enzymatic EZH2 inhibitors have shown limited efficacy in prostate cancer, warranting a more comprehensive understanding of EZH2 functions. Here we first review how canonical functions of EZH2 as a histone MTase are regulated and describe the various mechanisms of PRC2 recruitment to the chromatin. We further outline non-histone substrates of EZH2 and discuss post-translational modifications to EZH2 itself that may affect substrate preference. Lastly, we summarize non-canonical functions of EZH2, beyond its MTase activity and/or PRC2, as a transcriptional cofactor and discuss prospects of its therapeutic targeting in prostate cancer.
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Affiliation(s)
- Su H Park
- Division of Hematology/Oncology, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Ka-Wing Fong
- Division of Hematology/Oncology, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
- Department of Toxicology and Cancer Biology, University of Kentucky, Lexington, KY, USA
| | - Ezinne Mong
- Division of Hematology/Oncology, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - M Cynthia Martin
- Department of Chemistry, Northwestern University, Evanston, IL, USA
| | - Gary E Schiltz
- Department of Chemistry, Northwestern University, Evanston, IL, USA
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
- Robert H. Lurie Comprehensive Cancer Center, Northwestern University, Chicago, IL, USA
| | - Jindan Yu
- Division of Hematology/Oncology, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA.
- Robert H. Lurie Comprehensive Cancer Center, Northwestern University, Chicago, IL, USA.
- Department of Biochemistry and Molecular Genetics, Northwestern University Feinberg School of Medicine, Chicago, IL, USA.
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37
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Li C, Wang C. LG-ESSs and HG-ESSs: underlying molecular alterations and potential therapeutic strategies. J Zhejiang Univ Sci B 2021; 22:633-646. [PMID: 34414699 PMCID: PMC8377580 DOI: 10.1631/jzus.b2000797] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Revised: 03/19/2021] [Accepted: 03/19/2021] [Indexed: 12/29/2022]
Abstract
Endometrial stromal tumors (ESTs) include endometrial stromal nodule (ESN), low-grade endometrial stromal sarcoma (LG-ESS), high-grade endometrial stromal sarcoma (HG-ESS), and undifferentiated uterine sarcoma (UUS). Since these are rare tumor types, there is an unmet clinical need for the systematic therapy of advanced LG-ESS or HG-ESS. Cytogenetic and molecular advances in ESTs have shown that multiple recurrent gene fusions are present in a large proportion of LG-ESSs, and HG-ESSs are identified by the tyrosine 3-monooxygenase/tryptophan 5-monooxygenase activation protein epsilon (YWHAE)-family with sequence similarity 22 (FAM22) fusion. Recently, a group of ESSs harboring both zinc finger CCCH domain-containing protein 7B (ZC3H7B)-B-cell lymphoma 6 corepressor(BCOR) fusion and internal tandem duplication (ITD) of the BCOR gene have been provisionally classified as HG-ESSs. In this review, we firstly describe current knowledge about the molecular characteristics of recurrent aberrant proteins and their roles in the tumorigenesis of LG-ESSs and HG-ESSs. Next, we summarize the possibly shared signal pathways in the tumorigenesis of LG-ESSs and HG-ESSs, and list potentially actionable targets. Finally, based on the above discussion, we propose a few promising therapeutic strategies for LG-ESSs and HG-ESSs with recurrent gene alterations.
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Affiliation(s)
- Chunhui Li
- Quality Management Office, The Second Hospital of Jilin University, Changchun 130041, China
| | - Chunhong Wang
- Department of Hematology and Oncology, The Second Hospital of Jilin University, Changchun 130041, China.
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38
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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.
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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
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39
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Lin X, Leicher R, Liu S, Zhang B. Cooperative DNA looping by PRC2 complexes. Nucleic Acids Res 2021; 49:6238-6248. [PMID: 34057467 PMCID: PMC8216278 DOI: 10.1093/nar/gkab441] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2020] [Revised: 04/25/2021] [Accepted: 05/07/2021] [Indexed: 01/14/2023] Open
Abstract
Polycomb repressive complex 2 (PRC2) is an essential protein complex that silences gene expression via post-translational modifications of chromatin. This paper combined homology modeling, atomistic and coarse-grained molecular dynamics simulations, and single-molecule force spectroscopy experiments to characterize both its full-length structure and PRC2-DNA interactions. Using free energy calculations with a newly parameterized protein-DNA force field, we studied a total of three potential PRC2 conformations and their impact on DNA binding and bending. Consistent with cryo-EM studies, we found that EZH2, a core subunit of PRC2, provides the primary interface for DNA binding, and its curved surface can induce DNA bending. Our simulations also predicted the C2 domain of the SUZ12 subunit to contact DNA. Multiple PRC2 complexes bind with DNA cooperatively via allosteric communication through the DNA, leading to a hairpin-like looped configuration. Single-molecule experiments support PRC2-mediated DNA looping and the role of AEBP2 in regulating such loop formation. The impact of AEBP2 can be partly understood from its association with the C2 domain, blocking C2 from DNA binding. Our study suggests that accessory proteins may regulate the genomic location of PRC2 by interfering with its DNA interactions.
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Affiliation(s)
- Xingcheng Lin
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Rachel Leicher
- Laboratory of Nanoscale Biophysics and Biochemistry, The Rockefeller University, New York, NY 10065, USA.,Tri-Institutional PhD Program in Chemical Biology, New York, NY 10065, USA
| | - Shixin Liu
- Laboratory of Nanoscale Biophysics and Biochemistry, The Rockefeller University, New York, NY 10065, USA
| | - Bin Zhang
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, USA
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40
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Ghotbi E, Ye P, Ervin T, Kum A, Benes J, Jones RS. Polycomb-group recruitment to a Drosophila target gene is the default state that is inhibited by a transcriptional activator. SCIENCE ADVANCES 2021; 7:7/29/eabg1556. [PMID: 34272248 PMCID: PMC8284896 DOI: 10.1126/sciadv.abg1556] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Accepted: 05/25/2021] [Indexed: 06/13/2023]
Abstract
Polycomb-group (PcG) proteins are epigenetic regulators that maintain the transcriptional repression of target genes following their initial repression by transcription factors. PcG target genes are repressed in some cells, but active in others. Therefore, a mechanism must exist by which PcG proteins distinguish between the repressed and active states and only assemble repressive chromatin environments at target genes that are repressed. Here, we present experimental evidence that the repressed state of a Drosophila PcG target gene, giant (gt), is not identified by the presence of a repressor. Rather, de novo establishment of PcG-mediated silencing at gt is the default state that is prevented by the presence of an activator or coactivator, which may inhibit the catalytic activity of Polycomb-repressive complex 2 (PRC2).
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Affiliation(s)
- Elnaz Ghotbi
- Department of Biological Sciences, Southern Methodist University, Dallas, TX 75275-0376, USA
| | - Piao Ye
- Department of Biological Sciences, Southern Methodist University, Dallas, TX 75275-0376, USA
| | - Taylor Ervin
- Department of Biological Sciences, Southern Methodist University, Dallas, TX 75275-0376, USA
| | - Anni Kum
- Department of Biological Sciences, Southern Methodist University, Dallas, TX 75275-0376, USA
| | - Judith Benes
- Department of Biological Sciences, Southern Methodist University, Dallas, TX 75275-0376, USA
| | - Richard S Jones
- Department of Biological Sciences, Southern Methodist University, Dallas, TX 75275-0376, USA.
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41
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Petracovici A, Bonasio R. Distinct PRC2 subunits regulate maintenance and establishment of Polycomb repression during differentiation. Mol Cell 2021; 81:2625-2639.e5. [PMID: 33887196 PMCID: PMC8217195 DOI: 10.1016/j.molcel.2021.03.038] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Revised: 02/10/2021] [Accepted: 03/22/2021] [Indexed: 02/06/2023]
Abstract
The Polycomb repressive complex 2 (PRC2) is an essential epigenetic regulator that deposits repressive H3K27me3. PRC2 subunits form two holocomplexes-PRC2.1 and PRC2.2-but the roles of these two PRC2 assemblies during differentiation are unclear. We employed auxin-inducible degradation to deplete PRC2.1 subunit MTF2 or PRC2.2 subunit JARID2 during differentiation of embryonic stem cells (ESCs) to neural progenitors (NPCs). Depletion of either MTF2 or JARID2 resulted in incomplete differentiation due to defects in gene regulation. Distinct sets of Polycomb target genes were derepressed in the absence of MTF2 or JARID2. MTF2-sensitive genes were marked by H3K27me3 in ESCs and remained silent during differentiation, whereas JARID2-sensitive genes were preferentially active in ESCs and became newly repressed in NPCs. Thus, MTF2 and JARID2 contribute non-redundantly to Polycomb silencing, suggesting that PRC2.1 and PRC2.2 have distinct functions in maintaining and establishing, respectively, Polycomb repression during differentiation.
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Affiliation(s)
- Ana Petracovici
- Graduate Group in Cell and Molecular Biology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA; Epigenetics Institute, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA; Department of Cell and Developmental Biology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - Roberto Bonasio
- Epigenetics Institute, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA; Department of Cell and Developmental Biology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA.
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42
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Not just a writer: PRC2 as a chromatin reader. Biochem Soc Trans 2021; 49:1159-1170. [PMID: 34060617 PMCID: PMC8286813 DOI: 10.1042/bst20200728] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2021] [Revised: 05/06/2021] [Accepted: 05/07/2021] [Indexed: 12/16/2022]
Abstract
PRC2 deposits the H3K27me3 repressive mark, which facilitates transcription repression of developmental genes. The decision of whether a particular gene is silenced at a given point during development is heavily dependent on the chromatin context. More than just a simple epigenetic writer, PRC2 employs several distinct chromatin reading capabilities to sense the local chromatin environment and modulate the H3K27me3 writer activity in a context-dependent manner. Here we discuss the complex interplay of PRC2 with the hallmarks of active and repressive chromatin, how it affects H3K27me3 deposition and how it guides transcriptional activity.
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43
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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.
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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.
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44
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Engelberg IA, Liu J, Norris-Drouin JL, Cholensky SH, Ottavi SA, Frye SV, Kutateladze TG, James LI. Discovery of an H3K36me3-Derived Peptidomimetic Ligand with Enhanced Affinity for Plant Homeodomain Finger Protein 1 (PHF1). J Med Chem 2021; 64:8510-8522. [PMID: 33999620 DOI: 10.1021/acs.jmedchem.1c00430] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Plant homeodomain finger protein 1 (PHF1) is an accessory component of the gene silencing complex polycomb repressive complex 2 and recognizes the active chromatin mark, trimethylated lysine 36 of histone H3 (H3K36me3). In addition to its role in transcriptional regulation, PHF1 has been implicated as a driver of endometrial stromal sarcoma and fibromyxoid tumors. We report the discovery and characterization of UNC6641, a peptidomimetic antagonist of the PHF1 Tudor domain which was optimized through in silico modeling and incorporation of non-natural amino acids. UNC6641 binds the PHF1 Tudor domain with a Kd value of 0.96 ± 0.03 μM while also binding the related protein PHF19 with similar potency. A crystal structure of PHF1 in complex with UNC6641, along with NMR and site-directed mutagenesis data, provided insight into the binding mechanism and requirements for binding. Additionally, UNC6641 enabled the development of a high-throughput assay to identify small molecule binders of PHF1.
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Affiliation(s)
- Isabelle A Engelberg
- Center for Integrative Chemical Biology and Drug Discovery, Division of Chemical Biology and Medicinal Chemistry, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Jiuyang Liu
- Department of Pharmacology, University of Colorado School of Medicine, Aurora, Colorado 80045, United States
| | - Jacqueline L Norris-Drouin
- Center for Integrative Chemical Biology and Drug Discovery, Division of Chemical Biology and Medicinal Chemistry, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Stephanie H Cholensky
- Center for Integrative Chemical Biology and Drug Discovery, Division of Chemical Biology and Medicinal Chemistry, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Samantha A Ottavi
- Center for Integrative Chemical Biology and Drug Discovery, Division of Chemical Biology and Medicinal Chemistry, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Stephen V Frye
- Center for Integrative Chemical Biology and Drug Discovery, Division of Chemical Biology and Medicinal Chemistry, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Tatiana G Kutateladze
- Department of Pharmacology, University of Colorado School of Medicine, Aurora, Colorado 80045, United States
| | - Lindsey I James
- Center for Integrative Chemical Biology and Drug Discovery, Division of Chemical Biology and Medicinal Chemistry, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
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45
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Youmans DT, Gooding AR, Dowell RD, Cech TR. Competition between PRC2.1 and 2.2 subcomplexes regulates PRC2 chromatin occupancy in human stem cells. Mol Cell 2021; 81:488-501.e9. [PMID: 33338397 PMCID: PMC7867654 DOI: 10.1016/j.molcel.2020.11.044] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Revised: 10/05/2020] [Accepted: 11/23/2020] [Indexed: 12/12/2022]
Abstract
Polycomb repressive complex 2 (PRC2) silences expression of developmental transcription factors in pluripotent stem cells by methylating lysine 27 on histone H3. Two mutually exclusive subcomplexes, PRC2.1 and PRC2.2, are defined by the set of accessory proteins bound to the core PRC2 subunits. Here we introduce separation-of-function mutations into the SUZ12 subunit of PRC2 to drive it into a PRC2.1 or 2.2 subcomplex in human induced pluripotent stem cells (iPSCs). We find that PRC2.2 occupies polycomb target genes at low levels and that homeobox transcription factors are upregulated when this complex is exclusively present. In contrast with previous studies, we find that chromatin occupancy of PRC2 increases drastically when it is forced to form PRC2.1. Additionally, several cancer-associated mutations also coerce formation of PRC2.1. We suggest that PRC2 chromatin occupancy can be altered in the context of disease or development by tuning the ratio of PRC2.1 to PRC2.2.
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Affiliation(s)
- Daniel T Youmans
- BioFrontiers Institute, University of Colorado Boulder, Boulder, CO 80303, USA; Department of Biochemistry, University of Colorado Boulder, Boulder, CO 80303, USA; Medical Scientist Training Program, University of Colorado School of Medicine, Aurora, CO 80045, USA; Howard Hughes Medical Institute, University of Colorado Boulder, Boulder, CO 80303, USA
| | - Anne R Gooding
- Howard Hughes Medical Institute, University of Colorado Boulder, Boulder, CO 80303, USA
| | - Robin D Dowell
- BioFrontiers Institute, University of Colorado Boulder, Boulder, CO 80303, USA; Department of Molecular Cellular and Developmental Biology, University of Colorado Boulder, Boulder, CO 80303, USA
| | - Thomas R Cech
- BioFrontiers Institute, University of Colorado Boulder, Boulder, CO 80303, USA; Department of Biochemistry, University of Colorado Boulder, Boulder, CO 80303, USA; Howard Hughes Medical Institute, University of Colorado Boulder, Boulder, CO 80303, USA.
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46
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Mivelaz M, Fierz B. Observing protein interaction dynamics to chemically defined chromatin fibers by colocalization single-molecule fluorescence microscopy. Methods 2020; 184:112-124. [PMID: 32004546 DOI: 10.1016/j.ymeth.2020.01.018] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Revised: 01/15/2020] [Accepted: 01/26/2020] [Indexed: 02/04/2023] Open
Abstract
In eukaryotic cells, the genome is packaged into chromatin and exists in different states, ranging from open euchromatic regions to highly condensed heterochromatic regions. Chromatin states are highly dynamic and are organized by an interplay of histone post-translational modifications and effector proteins, both of which are central in the regulation of gene expression. For this, chromatin effector proteins must first search the nucleus for their targets, before binding and performing their role. A key question is how chromatin effector proteins search, interact with and alter the different chromatin environments. Here we present a modular fluorescence based in vitro workflow to directly observe dynamic interactions of effector proteins with defined chromatin fibres, replicating different chromatin states. We discuss the design and creation of chromatin assemblies, the synthesis of modified histones, the fabrication of microchannels and the approach to data acquisition and analysis. All of this with the aim to better understand the complex in vivo relationship between chromatin structure and gene expression.
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Affiliation(s)
- Maxime Mivelaz
- École Polytechnique Fédérale de Lausanne, SB ISIC LCBM, Station 6, CH-1015 Lausanne, Switzerland
| | - Beat Fierz
- École Polytechnique Fédérale de Lausanne, SB ISIC LCBM, Station 6, CH-1015 Lausanne, Switzerland.
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47
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Liu X. A Structural Perspective on Gene Repression by Polycomb Repressive Complex 2. Subcell Biochem 2020; 96:519-562. [PMID: 33252743 DOI: 10.1007/978-3-030-58971-4_17] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/30/2023]
Abstract
Polycomb Repressive Complex 2 (PRC2) is a major repressive chromatin complex formed by the Polycomb Group (PcG) proteins. PRC2 mediates trimethylation of histone H3 lysine 27 (H3K27me3), a hallmark of gene silencing. PRC2 is a key regulator of development, impacting many fundamental biological processes, like stem cell differentiation in mammals and vernalization in plants. Misregulation of PRC2 function is linked to a variety of human cancers and developmental disorders. In correlation with its diverse roles in development, PRC2 displays a high degree of compositional complexity and plasticity. Structural biology research over the past decade has shed light on the molecular mechanisms of the assembly, catalysis, allosteric activation, autoinhibition, chemical inhibition, dimerization and chromatin targeting of various developmentally regulated PRC2 complexes. In addition to these aspects, structure-function analysis is also discussed in connection with disease data in this chapter.
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Affiliation(s)
- Xin Liu
- Cecil H. and Ida Green Center for Reproductive Biology Sciences, UT Southwestern Medical Center, Dallas, TX, 75390, USA.
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Leicher R, Ge EJ, Lin X, Reynolds MJ, Xie W, Walz T, Zhang B, Muir TW, Liu S. Single-molecule and in silico dissection of the interaction between Polycomb repressive complex 2 and chromatin. Proc Natl Acad Sci U S A 2020; 117:30465-30475. [PMID: 33208532 PMCID: PMC7720148 DOI: 10.1073/pnas.2003395117] [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] [Indexed: 12/21/2022] Open
Abstract
Polycomb repressive complex 2 (PRC2) installs and spreads repressive histone methylation marks on eukaryotic chromosomes. Because of the key roles that PRC2 plays in development and disease, how this epigenetic machinery interacts with DNA and nucleosomes is of major interest. Nonetheless, the mechanism by which PRC2 engages with native-like chromatin remains incompletely understood. In this work, we employ single-molecule force spectroscopy and molecular dynamics simulations to dissect the behavior of PRC2 on polynucleosome arrays. Our results reveal an unexpectedly diverse repertoire of PRC2 binding configurations on chromatin. Besides reproducing known binding modes in which PRC2 interacts with bare DNA, mononucleosomes, and adjacent nucleosome pairs, our data also provide direct evidence that PRC2 can bridge pairs of distal nucleosomes. In particular, the "1-3" bridging mode, in which PRC2 engages two nucleosomes separated by one spacer nucleosome, is a preferred low-energy configuration. Moreover, we show that the distribution and stability of different PRC2-chromatin interaction modes are modulated by accessory subunits, oncogenic histone mutations, and the methylation state of chromatin. Overall, these findings have implications for the mechanism by which PRC2 spreads histone modifications and compacts chromatin. The experimental and computational platforms developed here provide a framework for understanding the molecular basis of epigenetic maintenance mediated by Polycomb-group proteins.
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Affiliation(s)
- Rachel Leicher
- Laboratory of Nanoscale Biophysics and Biochemistry, The Rockefeller University, New York, NY 10065
- Tri-Institutional PhD Program in Chemical Biology, New York, NY 10065
| | - Eva J Ge
- Department of Chemistry, Princeton University, Princeton, NJ 08544
| | - Xingcheng Lin
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Matthew J Reynolds
- Laboratory of Structural Biophysics and Mechanobiology, The Rockefeller University, New York, NY 10065
| | - Wenjun Xie
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Thomas Walz
- Laboratory of Molecular Electron Microscopy, The Rockefeller University, New York, NY 10065
| | - Bin Zhang
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139;
| | - Tom W Muir
- Department of Chemistry, Princeton University, Princeton, NJ 08544
| | - Shixin Liu
- Laboratory of Nanoscale Biophysics and Biochemistry, The Rockefeller University, New York, NY 10065;
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Villaseñor R, Baubec T. Regulatory mechanisms governing chromatin organization and function. Curr Opin Cell Biol 2020; 70:10-17. [PMID: 33276273 DOI: 10.1016/j.ceb.2020.10.015] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2020] [Revised: 10/26/2020] [Accepted: 10/30/2020] [Indexed: 12/12/2022]
Abstract
Nucleosomes, the basic structures used to package genetic information into chromatin, are subject to a diverse array of chemical modifications. A large number of these marks serve as interaction hubs for many nuclear proteins and provide critical structural features for protein recruitment. Dynamic deposition and removal of chromatin modifications by regulatory proteins ensure their correct deposition to the genome, which is essential for DNA replication, transcription, chromatin compaction, or DNA damage repair. The spatiotemporal regulation and maintenance of chromatin marks relies on coordinated activities of writer, eraser, and reader enzymes and often depends on complex multicomponent regulatory circuits. In recent years, the field has made enormous advances in uncovering the mechanisms that regulate chromatin modifications. Here, we discuss well-established and emerging concepts in chromatin biology ranging from cooperativity and multivalent interactions to regulatory feedback loops and increased local concentration of chromatin-modifying enzymes.
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Affiliation(s)
- Rodrigo Villaseñor
- Department of Molecular Mechanisms of Disease, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland.
| | - Tuncay Baubec
- Department of Molecular Mechanisms of Disease, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland.
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50
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Structural basis for PRC2 engagement with chromatin. Curr Opin Struct Biol 2020; 67:135-144. [PMID: 33232890 DOI: 10.1016/j.sbi.2020.10.017] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 10/14/2020] [Accepted: 10/19/2020] [Indexed: 02/08/2023]
Abstract
The polycomb repressive complex 2 (PRC2) is a conserved multiprotein, repressive chromatin complex essential for development and maintenance of eukaryotic cellular identity. PRC2 comprises a trimeric core of SUZ12, EED and EZH1/2, which together with RBBP4/7 is sufficient to catalyse mono-methylation, di-methylation and tri-methylation of histone H3 at lysine 27 (H3K27me1/2/3). These histone methyltransferase activities of PRC2 are deregulated in several human cancers and certain developmental disorders, such as Weaver Syndrome. Core PRC2 associates with several accessory proteins, which organise to define two main subassemblies, PRC2.1 and PRC2.2. Here we review new biochemical and structural studies that are providing critical insights into how core and accessory PRC2 subunits coordinate the faithful deposition of H3K27 methylations genome-wide.
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