1
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Uckelmann M, Levina V, Taveneau C, Ng XH, Pandey V, Martinez J, Mendiratta S, Houx J, Boudes M, Venugopal H, Trépout S, Zhang Q, Flanigan S, Li M, Sierecki E, Gambin Y, Das PP, Bell O, de Marco A, Davidovich C. Dynamic PRC1-CBX8 stabilizes a porous structure of chromatin condensates. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.05.08.539931. [PMID: 38405976 PMCID: PMC10888862 DOI: 10.1101/2023.05.08.539931] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/27/2024]
Abstract
The compaction of chromatin is a prevalent paradigm in gene repression. Chromatin compaction is commonly thought to repress transcription by restricting chromatin accessibility. However, the spatial organisation and dynamics of chromatin compacted by gene-repressing factors are unknown. Using cryo-electron tomography, we solved the three-dimensional structure of chromatin condensed by the Polycomb Repressive Complex 1 (PRC1) in a complex with CBX8. PRC1-condensed chromatin is porous and stabilised through multivalent dynamic interactions of PRC1 with chromatin. Mechanistically, positively charged residues on the internally disordered regions (IDRs) of CBX8 mask negative charges on the DNA to stabilize the condensed state of chromatin. Within condensates, PRC1 remains dynamic while maintaining a static chromatin structure. In differentiated mouse embryonic stem cells, CBX8-bound chromatin remains accessible. These findings challenge the idea of rigidly compacted polycomb domains and instead provides a mechanistic framework for dynamic and accessible PRC1-chromatin condensates.
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2
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Pang QY, Chiu YC, Huang RYJ. Regulating epithelial-mesenchymal plasticity from 3D genome organization. Commun Biol 2024; 7:750. [PMID: 38902393 PMCID: PMC11190238 DOI: 10.1038/s42003-024-06441-w] [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: 09/26/2022] [Accepted: 06/11/2024] [Indexed: 06/22/2024] Open
Abstract
Epithelial-mesenchymal transition (EMT) is a dynamic process enabling polarized epithelial cells to acquire mesenchymal features implicated in development and carcinoma progression. As our understanding evolves, it is clear the reversible execution of EMT arises from complex epigenomic regulation involving histone modifications and 3-dimensional (3D) genome structural changes, leading to a cascade of transcriptional events. This review summarizes current knowledge on chromatin organization in EMT, with a focus on hierarchical structures of the 3D genome and chromatin accessibility changes.
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Affiliation(s)
- Qing You Pang
- Neuro-Oncology Research Laboratory, National Neuroscience Institute, Singapore, 308433, Singapore
| | - Yi-Chia Chiu
- School of Medicine, College of Medicine, National Taiwan University, Taipei, 10051, Taiwan
| | - Ruby Yun-Ju Huang
- School of Medicine, College of Medicine, National Taiwan University, Taipei, 10051, Taiwan.
- Center for Advanced Computing and Imaging in Biomedicine, National Taiwan University, Taipei, 10051, Taiwan.
- Department of Obstetrics & Gynaecology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 119077, Singapore.
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3
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Gail EH, Healy E, Flanigan SF, Jones N, Ng XH, Uckelmann M, Levina V, Zhang Q, Davidovich C. Inseparable RNA binding and chromatin modification activities of a nucleosome-interacting surface in EZH2. Nat Genet 2024; 56:1193-1202. [PMID: 38744974 PMCID: PMC11176075 DOI: 10.1038/s41588-024-01740-8] [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: 06/12/2022] [Accepted: 04/02/2024] [Indexed: 05/16/2024]
Abstract
Polycomb repressive complex 2 (PRC2) interacts with RNA in cells, but there is no consensus on how RNA regulates PRC2 canonical functions, including chromatin modification and the maintenance of transcription programs in lineage-committed cells. We assayed two separation-of-function mutants of the PRC2 catalytic subunit EZH2, defective in RNA binding but functional in methyltransferase activity. We find that part of the RNA-binding surface of EZH2 is required for chromatin modification, yet this activity is independent of RNA. Mechanistically, the RNA-binding surface within EZH2 is required for chromatin modification in vitro and in cells, through interactions with nucleosomal DNA. Contrarily, an RNA-binding-defective mutant exhibited normal chromatin modification activity in vitro and in lineage-committed cells, accompanied by normal gene repression activity. Collectively, we show that part of the RNA-binding surface of EZH2, rather than the RNA-binding activity per se, is required for the histone methylation in vitro and in cells, through interactions with the substrate nucleosome.
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Affiliation(s)
- Emma H Gail
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, Victoria, Australia
| | - Evan Healy
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, Victoria, Australia
| | - Sarena F Flanigan
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, Victoria, Australia
| | - Natasha Jones
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, Victoria, Australia
| | - Xiao Han Ng
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, Victoria, Australia
| | - Michael Uckelmann
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, Victoria, Australia
| | - Vitalina Levina
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, Victoria, Australia
| | - Qi Zhang
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, Victoria, Australia.
- South Australian immunoGENomics Cancer Institute (SAiGENCI), Faculty of Health and Medical Sciences, University of Adelaide, Adelaide, South Australia, Australia.
- EMBL-Australia at SAiGENCI, Adelaide, South Australia, Australia.
| | - Chen Davidovich
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, Victoria, Australia.
- EMBL-Australia, Clayton, Victoria, Australia.
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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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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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6
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Song J, Gooding AR, Hemphill WO, Love BD, Robertson A, Yao L, Zon LI, North TE, Kasinath V, Cech TR. Structural basis for inactivation of PRC2 by G-quadruplex RNA. Science 2023; 381:1331-1337. [PMID: 37733873 PMCID: PMC11191771 DOI: 10.1126/science.adh0059] [Citation(s) in RCA: 21] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Accepted: 08/22/2023] [Indexed: 09/23/2023]
Abstract
Polycomb repressive complex 2 (PRC2) silences genes through trimethylation of histone H3K27. PRC2 associates with numerous precursor messenger RNAs (pre-mRNAs) and long noncoding RNAs (lncRNAs) with a binding preference for G-quadruplex RNA. In this work, we present a 3.3-Å-resolution cryo-electron microscopy structure of PRC2 bound to a G-quadruplex RNA. Notably, RNA mediates the dimerization of PRC2 by binding both protomers and inducing a protein interface composed of two copies of the catalytic subunit EZH2, thereby blocking nucleosome DNA interaction and histone H3 tail accessibility. Furthermore, an RNA-binding loop of EZH2 facilitates the handoff between RNA and DNA, another activity implicated in PRC2 regulation by RNA. We identified a gain-of-function mutation in this loop that activates PRC2 in zebrafish. Our results reveal mechanisms for RNA-mediated regulation of a chromatin-modifying enzyme.
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Affiliation(s)
- Jiarui Song
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO 80303, USA
- BioFrontiers Institute, University of Colorado Boulder, Boulder, CO 80303, USA
- Howard Hughes Medical Institute, University of Colorado Boulder, Boulder, CO 80303, USA
| | - Anne R. Gooding
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO 80303, USA
- BioFrontiers Institute, University of Colorado Boulder, Boulder, CO 80303, USA
- Howard Hughes Medical Institute, University of Colorado Boulder, Boulder, CO 80303, USA
| | - Wayne O. Hemphill
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO 80303, USA
- BioFrontiers Institute, University of Colorado Boulder, Boulder, CO 80303, USA
- Howard Hughes Medical Institute, University of Colorado Boulder, Boulder, CO 80303, USA
| | - Brittney D. Love
- Stem Cell and Regenerative Biology Department, Harvard University, Cambridge, MA 02138, USA
- Stem Cell Program, Division of Hematology/Oncology, Boston Children’s Hospital and Dana-Farber Cancer Institute, Boston, MA 02115, USA
- Harvard Medical School, Boston, MA 02115, USA
| | - Anne Robertson
- Stem Cell and Regenerative Biology Department, Harvard University, Cambridge, MA 02138, USA
- Stem Cell Program, Division of Hematology/Oncology, Boston Children’s Hospital and Dana-Farber Cancer Institute, Boston, MA 02115, USA
- Harvard Medical School, Boston, MA 02115, USA
- Howard Hughes Medical Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Liqi Yao
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO 80303, USA
| | - Leonard I. Zon
- Stem Cell and Regenerative Biology Department, Harvard University, Cambridge, MA 02138, USA
- Stem Cell Program, Division of Hematology/Oncology, Boston Children’s Hospital and Dana-Farber Cancer Institute, Boston, MA 02115, USA
- Harvard Medical School, Boston, MA 02115, USA
- Howard Hughes Medical Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Trista E. North
- Stem Cell and Regenerative Biology Department, Harvard University, Cambridge, MA 02138, USA
- Stem Cell Program, Division of Hematology/Oncology, Boston Children’s Hospital and Dana-Farber Cancer Institute, Boston, MA 02115, USA
- Harvard Medical School, Boston, MA 02115, USA
| | - Vignesh Kasinath
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO 80303, USA
| | - Thomas R. Cech
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO 80303, USA
- BioFrontiers Institute, University of Colorado Boulder, Boulder, CO 80303, USA
- Howard Hughes Medical Institute, University of Colorado Boulder, Boulder, CO 80303, USA
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7
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Song J, Gooding AR, Hemphill WO, Kasinath V, Cech TR. Structural basis for inactivation of PRC2 by G-quadruplex RNA. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.06.527314. [PMID: 36798278 PMCID: PMC9934548 DOI: 10.1101/2023.02.06.527314] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The histone methyltransferase PRC2 (Polycomb Repressive Complex 2) silences genes via successively attaching three methyl groups to lysine 27 of histone H3. PRC2 associates with numerous pre-mRNA and lncRNA transcripts with a binding preference for G-quadruplex RNA. Here, we present a 3.3Ã…-resolution cryo-EM structure of PRC2 bound to a G-quadruplex RNA. Notably, RNA mediates the dimerization of PRC2 by binding both protomers and inducing a protein interface comprised of two copies of the catalytic subunit EZH2, which limits nucleosome DNA interaction and occludes H3 tail accessibility to the active site. Our results reveal an unexpected mechanism for RNA-mediated inactivation of a chromatin-modifying enzyme. Furthermore, the flexible loop of EZH2 that helps stabilize RNA binding also facilitates the handoff between RNA and DNA, an activity implicated in PRC2 regulation by RNA. One-Sentence Summary Cryo-EM structure of RNA-bound PRC2 dimer elucidates an unexpected mechanism of PRC2 inhibition by RNA.
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8
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Huang L, Li F, Ye L, Yu F, Wang C. Epigenetic regulation of embryonic ectoderm development in stem cell differentiation and transformation during ontogenesis. Cell Prolif 2023; 56:e13413. [PMID: 36727213 PMCID: PMC10068960 DOI: 10.1111/cpr.13413] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Revised: 01/09/2023] [Accepted: 01/18/2023] [Indexed: 02/03/2023] Open
Abstract
Dynamic chromatin accessibility regulates stem cell fate determination and tissue homeostasis via controlling gene expression. As a histone-modifying enzyme that predominantly mediates methylation of lysine 27 in histone H3 (H3K27me1/2/3), Polycomb repressive complex 2 (PRC2) plays the canonical role in targeting developmental regulators during stem cell differentiation and transformation. Embryonic ectoderm development (EED), the core scaffold subunit of PRC2 and as an H3K27me3-recognizing protein, has been broadly implicated with PRC2 stabilization and allosterically stimulated PRC2. Accumulating evidences from experimental data indicate that EED-associating epigenetic modifications are indispensable for stem cell maintenance and differentiation into specific cell lineages. In this review, we discuss the most updated advances to summarize the structural architecture of EED and its contributions and underlying mechanisms to mediating lineage differentiation of different stem cells during epigenetic modification to expand our understanding of PRC2.
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Affiliation(s)
- Liuyan Huang
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China.,Department of Endodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Feifei Li
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Ling Ye
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China.,Department of Endodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Fanyuan Yu
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China.,Department of Endodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Chenglin Wang
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China.,Department of Endodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
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9
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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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10
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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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11
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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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12
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Tavares M, Khandelwal G, Muter J, Viiri K, Beltran M, Brosens JJ, Jenner RG. JAZF1-SUZ12 dysregulates PRC2 function and gene expression during cell differentiation. Cell Rep 2022; 39:110889. [PMID: 35649353 PMCID: PMC9637993 DOI: 10.1016/j.celrep.2022.110889] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Revised: 03/04/2022] [Accepted: 05/06/2022] [Indexed: 11/03/2022] Open
Abstract
Polycomb repressive complex 2 (PRC2) methylates histone H3 lysine 27 (H3K27me3) to maintain gene repression and is essential for cell differentiation. In low-grade endometrial stromal sarcoma (LG-ESS), the PRC2 subunit SUZ12 is often fused with the NuA4/TIP60 subunit JAZF1. We show that JAZF1-SUZ12 dysregulates PRC2 composition, genome occupancy, histone modification, gene expression, and cell differentiation. Loss of the SUZ12 N terminus in the fusion protein abrogates interaction with specific PRC2 accessory factors, reduces occupancy at PRC2 target genes, and diminishes H3K27me3. Fusion to JAZF1 increases H4Kac at PRC2 target genes and triggers recruitment to JAZF1 binding sites during cell differentiation. In human endometrial stromal cells, JAZF1-SUZ12 upregulated PRC2 target genes normally activated during decidualization while repressing genes associated with immune clearance, and JAZF1-SUZ12-induced genes were also overexpressed in LG-ESS. These results reveal defects in chromatin regulation, gene expression, and cell differentiation caused by JAZF1-SUZ12 that may underlie its role in oncogenesis.
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Affiliation(s)
- Manuel Tavares
- UCL Cancer Institute and Cancer Research UK UCL Centre, University College London (UCL), London WC1E 6BT, UK
| | - Garima Khandelwal
- UCL Cancer Institute and Cancer Research UK UCL Centre, University College London (UCL), London WC1E 6BT, UK
| | - Joanne Muter
- Warwick Medical School, Division of Biomedical Sciences, University of Warwick, Coventry CV4 7AL, UK
| | - Keijo Viiri
- UCL Cancer Institute and Cancer Research UK UCL Centre, University College London (UCL), London WC1E 6BT, UK
| | - Manuel Beltran
- UCL Cancer Institute and Cancer Research UK UCL Centre, University College London (UCL), London WC1E 6BT, UK
| | - Jan J Brosens
- Warwick Medical School, Division of Biomedical Sciences, University of Warwick, Coventry CV4 7AL, UK
| | - Richard G Jenner
- UCL Cancer Institute and Cancer Research UK UCL Centre, University College London (UCL), London WC1E 6BT, UK.
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13
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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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14
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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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15
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Oncohistone interactome profiling uncovers contrasting oncogenic mechanisms and identifies potential therapeutic targets in high grade glioma. Acta Neuropathol 2022; 144:1027-1048. [PMID: 36070144 PMCID: PMC9547787 DOI: 10.1007/s00401-022-02489-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Revised: 08/22/2022] [Accepted: 08/27/2022] [Indexed: 01/26/2023]
Abstract
Histone H3 mutations at amino acids 27 (H3K27M) and 34 (H3G34R) are recurrent drivers of pediatric-type high-grade glioma (pHGG). H3K27M mutations lead to global disruption of H3K27me3 through dominant negative PRC2 inhibition, while H3G34R mutations lead to local losses of H3K36me3 through inhibition of SETD2. However, their broader oncogenic mechanisms remain unclear. We characterized the H3.1K27M, H3.3K27M and H3.3G34R interactomes, finding that H3K27M is associated with epigenetic and transcription factor changes; in contrast H3G34R removes a break on cryptic transcription, limits DNA methyltransferase access, and alters mitochondrial metabolism. All 3 mutants had altered interactions with DNA repair proteins and H3K9 methyltransferases. H3K9me3 was reduced in H3K27M-containing nucleosomes, and cis-H3K9 methylation was required for H3K27M to exert its effect on global H3K27me3. H3K9 methyltransferase inhibition was lethal to H3.1K27M, H3.3K27M and H3.3G34R pHGG cells, underscoring the importance of H3K9 methylation for oncohistone-mutant gliomas and suggesting it as an attractive therapeutic target.
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16
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Structural insights into the interactions of Polycomb Repressive Complex 2 with chromatin. Biochem Soc Trans 2021; 49:2639-2653. [PMID: 34747969 DOI: 10.1042/bst20210450] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Revised: 09/21/2021] [Accepted: 10/18/2021] [Indexed: 12/12/2022]
Abstract
Polycomb repressive complexes are a family of chromatin modifier enzymes which are critical for regulating gene expression and maintaining cell-type identity. The reversible chemical modifications of histone H3 and H2A by the Polycomb proteins are central to its ability to function as a gene silencer. PRC2 is both a reader and writer of the tri-methylation of histone H3 lysine 27 (H3K27me3) which serves as a marker for transcription repression, and heterochromatin boundaries. Over the last few years, several studies have provided key insights into the mechanisms regulating the recruitment and activation of PRC2 at Polycomb target genes. In this review, we highlight the recent structural studies which have elucidated the roles played by Polycomb cofactor proteins in mediating crosstalk between histone post-translational modifications and the recruitment of PRC2 and the stimulation of PRC2 methyltransferase activity.
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17
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Wang S, C Ordonez-Rubiano S, Dhiman A, Jiao G, Strohmier BP, Krusemark CJ, Dykhuizen EC. Polycomb group proteins in cancer: multifaceted functions and strategies for modulation. NAR Cancer 2021; 3:zcab039. [PMID: 34617019 PMCID: PMC8489530 DOI: 10.1093/narcan/zcab039] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Revised: 08/24/2021] [Accepted: 09/10/2021] [Indexed: 12/12/2022] Open
Abstract
Polycomb repressive complexes (PRCs) are a heterogenous collection of dozens, if not hundreds, of protein complexes composed of various combinations of subunits. PRCs are transcriptional repressors important for cell-type specificity during development, and as such, are commonly mis-regulated in cancer. PRCs are broadly characterized as PRC1 with histone ubiquitin ligase activity, or PRC2 with histone methyltransferase activity; however, the mechanism by which individual PRCs, particularly the highly diverse set of PRC1s, alter gene expression has not always been clear. Here we review the current understanding of how PRCs act, both individually and together, to establish and maintain gene repression, the biochemical contribution of individual PRC subunits, the mis-regulation of PRC function in different cancers, and the current strategies for modulating PRC activity. Increased mechanistic understanding of PRC function, as well as cancer-specific roles for individual PRC subunits, will uncover better targets and strategies for cancer therapies.
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Affiliation(s)
- Sijie Wang
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University and Purdue University Center for Cancer Research, 201 S. University St., West Lafayette, IN 47907 USA
| | - Sandra C Ordonez-Rubiano
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University and Purdue University Center for Cancer Research, 201 S. University St., West Lafayette, IN 47907 USA
| | - Alisha Dhiman
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University and Purdue University Center for Cancer Research, 201 S. University St., West Lafayette, IN 47907 USA
| | - Guanming Jiao
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University and Purdue University Center for Cancer Research, 201 S. University St., West Lafayette, IN 47907 USA
| | - Brayden P Strohmier
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University and Purdue University Center for Cancer Research, 201 S. University St., West Lafayette, IN 47907 USA
| | - Casey J Krusemark
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University and Purdue University Center for Cancer Research, 201 S. University St., West Lafayette, IN 47907 USA
| | - Emily C Dykhuizen
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University and Purdue University Center for Cancer Research, 201 S. University St., West Lafayette, IN 47907 USA
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