1
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Ukmar‐Godec T, Yu T, de Opakua AI, Pantoja CF, Munari F, Zweckstetter M. Conformational diversity of human HP1α. Protein Sci 2024; 33:e5079. [PMID: 38895997 PMCID: PMC11187854 DOI: 10.1002/pro.5079] [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: 02/29/2024] [Revised: 05/27/2024] [Accepted: 05/30/2024] [Indexed: 06/21/2024]
Abstract
Heterochromatin protein 1 alpha (HP1α) is an evolutionarily conserved protein that binds chromatin and is important for gene silencing. The protein comprises 191 residues arranged into three disordered regions and two structured domains, the chromo and chromoshadow domain, which associates into a homodimer. While high-resolution structures of the isolated domains of HP1 proteins are known, the structural properties of full-length HP1α remain largely unknown. Using a combination of NMR spectroscopy and structure predictions by AlphaFold2 we provide evidence that the chromo and chromoshadow domain of HP1α engage in direct contacts resulting in a compact chromo/chromoshadow domain arrangement. We further show that HP1β and HP1γ have increased interdomain dynamics when compared to HP1α which may contribute to the distinct roles of different Hp1 isoforms in gene silencing and activation.
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Affiliation(s)
- Tina Ukmar‐Godec
- German Center for Neurodegenerative Diseases (DZNE)Translational Structural BiologyGöttingenGermany
| | - Taekyung Yu
- German Center for Neurodegenerative Diseases (DZNE)Translational Structural BiologyGöttingenGermany
| | - Alain Ibanez de Opakua
- German Center for Neurodegenerative Diseases (DZNE)Translational Structural BiologyGöttingenGermany
| | - Christian F. Pantoja
- German Center for Neurodegenerative Diseases (DZNE)Translational Structural BiologyGöttingenGermany
| | | | - Markus Zweckstetter
- German Center for Neurodegenerative Diseases (DZNE)Translational Structural BiologyGöttingenGermany
- Department of NMR‐based Structural BiologyMax Planck Institute for Multidisciplinary SciencesGöttingenGermany
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2
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Phan TM, Kim YC, Debelouchina GT, Mittal J. Interplay between charge distribution and DNA in shaping HP1 paralog phase separation and localization. eLife 2024; 12:RP90820. [PMID: 38592759 PMCID: PMC11003746 DOI: 10.7554/elife.90820] [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: 04/10/2024] Open
Abstract
The heterochromatin protein 1 (HP1) family is a crucial component of heterochromatin with diverse functions in gene regulation, cell cycle control, and cell differentiation. In humans, there are three paralogs, HP1α, HP1β, and HP1γ, which exhibit remarkable similarities in their domain architecture and sequence properties. Nevertheless, these paralogs display distinct behaviors in liquid-liquid phase separation (LLPS), a process linked to heterochromatin formation. Here, we employ a coarse-grained simulation framework to uncover the sequence features responsible for the observed differences in LLPS. We highlight the significance of the net charge and charge patterning along the sequence in governing paralog LLPS propensities. We also show that both highly conserved folded and less-conserved disordered domains contribute to the observed differences. Furthermore, we explore the potential co-localization of different HP1 paralogs in multicomponent assemblies and the impact of DNA on this process. Importantly, our study reveals that DNA can significantly reshape the stability of a minimal condensate formed by HP1 paralogs due to competitive interactions of HP1α with HP1β and HP1γ versus DNA. In conclusion, our work highlights the physicochemical nature of interactions that govern the distinct phase-separation behaviors of HP1 paralogs and provides a molecular framework for understanding their role in chromatin organization.
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Affiliation(s)
- Tien M Phan
- Artie McFerrin Department of Chemical Engineering, Texas A&M UniversityCollege StationUnited States
| | - Young C Kim
- Center for Materials Physics and Technology, Naval Research LaboratoryWashingtonUnited States
| | - Galia T Debelouchina
- Department of Chemistry and Biochemistry, University of California, San DiegoLa JollaUnited States
| | - Jeetain Mittal
- Artie McFerrin Department of Chemical Engineering, Texas A&M UniversityCollege StationUnited States
- Department of Chemistry, Texas A&M UniversityCollege StationUnited States
- Interdisciplinary Graduate Program in Genetics and Genomics, Texas A&M UniversityCollege StationUnited States
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3
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Tam PLF, Cheung MF, Chan LY, Leung D. Cell-type differential targeting of SETDB1 prevents aberrant CTCF binding, chromatin looping, and cis-regulatory interactions. Nat Commun 2024; 15:15. [PMID: 38167730 PMCID: PMC10762014 DOI: 10.1038/s41467-023-44578-0] [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: 08/18/2023] [Accepted: 12/19/2023] [Indexed: 01/05/2024] Open
Abstract
SETDB1 is an essential histone methyltransferase that deposits histone H3 lysine 9 trimethylation (H3K9me3) to transcriptionally repress genes and repetitive elements. The function of differential H3K9me3 enrichment between cell-types remains unclear. Here, we demonstrate mutual exclusivity of H3K9me3 and CTCF across mouse tissues from different developmental timepoints. We analyze SETDB1 depleted cells and discover that H3K9me3 prevents aberrant CTCF binding independently of DNA methylation and H3K9me2. Such sites are enriched with SINE B2 retrotransposons. Moreover, analysis of higher-order genome architecture reveals that large chromatin structures including topologically associated domains and subnuclear compartments, remain intact in SETDB1 depleted cells. However, chromatin loops and local 3D interactions are disrupted, leading to transcriptional changes by modifying pre-existing chromatin landscapes. Specific genes with altered expression show differential interactions with dysregulated cis-regulatory elements. Collectively, we find that cell-type specific targets of SETDB1 maintain cellular identities by modulating CTCF binding, which shape nuclear architecture and transcriptomic networks.
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Affiliation(s)
- Phoebe Lut Fei Tam
- Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, SAR, China
| | - Ming Fung Cheung
- Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, SAR, China
- Center for Epigenomics Research, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, SAR, China
| | - Lu Yan Chan
- Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, SAR, China
- Center for Epigenomics Research, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, SAR, China
| | - Danny Leung
- Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, SAR, China.
- Center for Epigenomics Research, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, SAR, China.
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4
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Ukmar-Godec T, Cima-Omori MS, Yerkesh Z, Eswara K, Yu T, Ramesh R, Riviere G, Ibanez de Opakua A, Fischle W, Zweckstetter M. Multimodal interactions drive chromatin phase separation and compaction. Proc Natl Acad Sci U S A 2023; 120:e2308858120. [PMID: 38048471 PMCID: PMC10723116 DOI: 10.1073/pnas.2308858120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Accepted: 11/01/2023] [Indexed: 12/06/2023] Open
Abstract
Gene silencing is intimately connected to DNA condensation and the formation of transcriptionally inactive heterochromatin by Heterochromatin Protein 1α (HP1α). Because heterochromatin foci are dynamic and HP1α can promote liquid-liquid phase separation, HP1α-mediated phase separation has been proposed as a mechanism of chromatin compaction. The molecular basis of HP1α-driven phase separation and chromatin compaction and the associated regulation by trimethylation of lysine 9 in histone 3 (H3K9me3), which is the hallmark of constitutive heterochromatin, is however largely unknown. Using a combination of chromatin compaction and phase separation assays, site-directed mutagenesis, and NMR-based interaction analysis, we show that human HP1α can compact chromatin in the absence of liquid-liquid phase separation. We further demonstrate that H3K9-trimethylation promotes compaction of chromatin arrays through multimodal interactions. The results provide molecular insights into HP1α-mediated chromatin compaction and thus into the role of human HP1α in the regulation of gene silencing.
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Affiliation(s)
- Tina Ukmar-Godec
- German Center for Neurodegenerative Diseases, Translational Structural Biology, Göttingen37075, Germany
| | - Maria-Sol Cima-Omori
- German Center for Neurodegenerative Diseases, Translational Structural Biology, Göttingen37075, Germany
| | - Zhadyra Yerkesh
- Bioscience Program, Biological and Environmental Science and Engineering Division, Laboratory of Chromatin Biochemistry, King Abdullah University of Science and Technology, Thuwal23955, Saudi Arabia
| | - Karthik Eswara
- Bioscience Program, Biological and Environmental Science and Engineering Division, Laboratory of Chromatin Biochemistry, King Abdullah University of Science and Technology, Thuwal23955, Saudi Arabia
| | - Taekyung Yu
- German Center for Neurodegenerative Diseases, Translational Structural Biology, Göttingen37075, Germany
| | - Reshma Ramesh
- German Center for Neurodegenerative Diseases, Translational Structural Biology, Göttingen37075, Germany
| | - Gwladys Riviere
- German Center for Neurodegenerative Diseases, Translational Structural Biology, Göttingen37075, Germany
| | - Alain Ibanez de Opakua
- German Center for Neurodegenerative Diseases, Translational Structural Biology, Göttingen37075, Germany
| | - Wolfgang Fischle
- Bioscience Program, Biological and Environmental Science and Engineering Division, Laboratory of Chromatin Biochemistry, King Abdullah University of Science and Technology, Thuwal23955, Saudi Arabia
| | - Markus Zweckstetter
- German Center for Neurodegenerative Diseases, Translational Structural Biology, Göttingen37075, Germany
- Department of NMR-based Structural Biology, Max Planck Institute for Multidisciplinary Sciences, Göttingen37077, Germany
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5
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Parra AS, Johnston CA. Phase Separation as a Driver of Stem Cell Organization and Function during Development. J Dev Biol 2023; 11:45. [PMID: 38132713 PMCID: PMC10743522 DOI: 10.3390/jdb11040045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2023] [Revised: 12/04/2023] [Accepted: 12/08/2023] [Indexed: 12/23/2023] Open
Abstract
A properly organized subcellular composition is essential to cell function. The canonical organizing principle within eukaryotic cells involves membrane-bound organelles; yet, such structures do not fully explain cellular complexity. Furthermore, discrete non-membrane-bound structures have been known for over a century. Liquid-liquid phase separation (LLPS) has emerged as a ubiquitous mode of cellular organization without the need for formal lipid membranes, with an ever-expanding and diverse list of cellular functions that appear to be regulated by this process. In comparison to traditional organelles, LLPS can occur across wider spatial and temporal scales and involves more distinct protein and RNA complexes. In this review, we discuss the impacts of LLPS on the organization of stem cells and their function during development. Specifically, the roles of LLPS in developmental signaling pathways, chromatin organization, and gene expression will be detailed, as well as its impacts on essential processes of asymmetric cell division. We will also discuss how the dynamic and regulated nature of LLPS may afford stem cells an adaptable mode of organization throughout the developmental time to control cell fate. Finally, we will discuss how aberrant LLPS in these processes may contribute to developmental defects and disease.
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6
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Phan TM, Kim YC, Debelouchina GT, Mittal J. Interplay between charge distribution and DNA in shaping HP1 paralog phase separation and localization. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.28.542535. [PMID: 37398008 PMCID: PMC10312469 DOI: 10.1101/2023.05.28.542535] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
The heterochromatin protein 1 (HP1) family is a crucial component of heterochromatin with diverse functions in gene regulation, cell cycle control, and cell differentiation. In humans, there are three paralogs, HP1α, HP1β, and HP1γ, which exhibit remarkable similarities in their domain architecture and sequence properties. Nevertheless, these paralogs display distinct behaviors in liquid-liquid phase separation (LLPS), a process linked to heterochromatin formation. Here, we employ a coarse-grained simulation framework to uncover the sequence features responsible for the observed differences in LLPS. We highlight the significance of the net charge and charge patterning along the sequence in governing paralog LLPS propensities. We also show that both highly conserved folded and less-conserved disordered domains contribute to the observed differences. Furthermore, we explore the potential co-localization of different HP1 paralogs in multicomponent assemblies and the impact of DNA on this process. Importantly, our study reveals that DNA can significantly reshape the stability of a minimal condensate formed by HP1 paralogs due to competitive interactions of HP1α with HP1β and HP1γ versus DNA. In conclusion, our work highlights the physicochemical nature of interactions that govern the distinct phase-separation behaviors of HP1 paralogs and provides a molecular framework for understanding their role in chromatin organization.
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Affiliation(s)
- Tien M. Phan
- Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station, TX, USA
| | - Young C. Kim
- Center for Materials Physics and Technology, Naval Research Laboratory, Washington, DC, USA
| | - Galia T. Debelouchina
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, CA, USA
| | - Jeetain Mittal
- Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station, TX, USA
- Department of Chemistry, Texas A&M University, College Station, TX, USA
- Interdisciplinary Graduate Program in Genetics and Genomics, Texas A&M University, College Station, TX, USA
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7
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Abstract
The eukaryotic nucleus displays a variety of membraneless compartments with distinct biomolecular composition and specific cellular activities. Emerging evidence indicates that protein-based liquid-liquid phase separation (LLPS) plays an essential role in the formation and dynamic regulation of heterochromatin compartmentalization. This feature is especially conspicuous at the pericentric heterochromatin domains. In this review, we will describe our understanding of heterochromatin organization and LLPS. In addition, we will highlight the increasing importance of multivalent weak homo- and heteromolecular interactions in LLPS-mediated heterochromatin compartmentalization in the complex environment inside living cells.
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Affiliation(s)
- Hui Zhang
- Cell Biology and Epigenetics, Department of Biology, Technical University of Darmstadt, Darmstadt, Germany
| | - Weihua Qin
- Human Biology and Bioimaging, Faculty of Biology, Ludwig Maximilians University Munich, Planegg-Martinsried, Germany
| | - Hector Romero
- Cell Biology and Epigenetics, Department of Biology, Technical University of Darmstadt, Darmstadt, Germany
| | - Heinrich Leonhardt
- Human Biology and Bioimaging, Faculty of Biology, Ludwig Maximilians University Munich, Planegg-Martinsried, Germany
| | - M. Cristina Cardoso
- Cell Biology and Epigenetics, Department of Biology, Technical University of Darmstadt, Darmstadt, Germany,CONTACT M. Cristina Cardoso Cell Biology and Epigenetics, Department of Biology, Technical University of Darmstadt, Schnittspahnstr. 10, 64287Darmstadt, Germany
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8
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Rajshekar S, Adame-Arana O, Bajpai G, Lin K, Colmenares S, Safran S, Karpen GH. Affinity hierarchies and amphiphilic proteins underlie the co-assembly of nucleolar and heterochromatin condensates. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.06.547894. [PMID: 37808710 PMCID: PMC10557603 DOI: 10.1101/2023.07.06.547894] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/10/2023]
Abstract
Nucleoli are surrounded by Pericentromeric Heterochromatin (PCH), reflecting a close spatial association between the two largest biomolecular condensates in eukaryotic nuclei. This nuclear organizational feature is highly conserved and is disrupted in diseased states like senescence, however, the mechanisms driving PCH-nucleolar association are unclear. High-resolution live imaging during early Drosophila development revealed a highly dynamic process in which PCH and nucleolar formation is coordinated and interdependent. When nucleolus assembly was eliminated by deleting the ribosomal RNA genes (rDNA), PCH showed increased compaction and subsequent reorganization to a shell-like structure. In addition, in embryos lacking rDNA, some nucleolar proteins were redistributed into new bodies or 'neocondensates,' including enrichment in the core of the PCH shell. These observations, combined with physical modeling and simulations, suggested that nucleolar-PCH associations are mediated by a hierarchy of affinities between PCH, nucleoli, and 'amphiphilic' protein(s) that interact with both nucleolar and PCH components. This result was validated by demonstrating that the depletion of one candidate amphiphile, the nucleolar protein Pitchoune, significantly reduced PCH-nucleolar associations. Together, these results unveil a dynamic program for establishing nucleolar-PCH associations during animal development, demonstrate that nucleoli are required for normal PCH organization, and identify Pitchoune as an amphiphilic molecular link that promotes PCH-nucleolar associations. Finally, we propose that disrupting affinity hierarchies between interacting condensates can liberate molecules to form neocondensates or other aberrant structures that could contribute to cellular disease phenotypes.
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Affiliation(s)
- Srivarsha Rajshekar
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, USA
| | - Omar Adame-Arana
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot, Israel
- Max Planck Institute for the Physics of Complex Systems, Dresden, Germany
| | - Gaurav Bajpai
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot, Israel
| | - Kyle Lin
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, USA
| | - Serafin Colmenares
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, USA
| | - Samuel Safran
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot, Israel
| | - Gary H Karpen
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, USA
- Division of Biological Sciences and the Environment, Lawrence Berkeley National Laboratory, Berkeley, USA
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9
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Her C, Phan TM, Jovic N, Kapoor U, Ackermann BE, Rizuan A, Kim Y, Mittal J, Debelouchina G. Molecular interactions underlying the phase separation of HP1α: role of phosphorylation, ligand and nucleic acid binding. Nucleic Acids Res 2022; 50:12702-12722. [PMID: 36537242 PMCID: PMC9825191 DOI: 10.1093/nar/gkac1194] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2022] [Revised: 11/04/2022] [Accepted: 12/05/2022] [Indexed: 12/24/2022] Open
Abstract
Heterochromatin protein 1α (HP1α) is a crucial element of chromatin organization. It has been proposed that HP1α functions through liquid-liquid phase separation (LLPS), which allows it to compact chromatin into transcriptionally repressed heterochromatin regions. In vitro, HP1α can undergo phase separation upon phosphorylation of its N-terminus extension (NTE) and/or through interactions with DNA and chromatin. Here, we combine computational and experimental approaches to elucidate the molecular interactions that drive these processes. In phosphorylation-driven LLPS, HP1α can exchange intradimer hinge-NTE interactions with interdimer contacts, which also leads to a structural change from a compacted to an extended HP1α dimer conformation. This process can be enhanced by the presence of positively charged HP1α peptide ligands and disrupted by the addition of negatively charged or neutral peptides. In DNA-driven LLPS, both positively and negatively charged peptide ligands can perturb phase separation. Our findings demonstrate the importance of electrostatic interactions in HP1α LLPS where binding partners can modulate the overall charge of the droplets and screen or enhance hinge region interactions through specific and non-specific effects. Our study illuminates the complex molecular framework that can fine-tune the properties of HP1α and that can contribute to heterochromatin regulation and function.
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Affiliation(s)
| | | | - Nina Jovic
- Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station, TX, USA
| | - Utkarsh Kapoor
- Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station, TX, USA
| | - Bryce E Ackermann
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, CA, USA
| | - Azamat Rizuan
- Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station, TX, USA
| | - Young C Kim
- Center for Materials Physics and Technology, Naval Research Laboratory, WA, DC, USA
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10
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Ancona M, Brackley CA. Simulating the chromatin mediated phase separation of model proteins with multiple domains. Biophys J 2022; 121:2600-2612. [DOI: 10.1016/j.bpj.2022.05.039] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Revised: 04/28/2022] [Accepted: 05/24/2022] [Indexed: 11/28/2022] Open
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11
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Liu Y, Yang X, Zhou M, Yang Y, Li F, Yan X, Zhang M, Wei Z, Qin S, Min J. Structural basis for the recognition of methylated histone H3 by the Arabidopsis LHP1 chromodomain. J Biol Chem 2022; 298:101623. [PMID: 35074427 PMCID: PMC8861120 DOI: 10.1016/j.jbc.2022.101623] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Revised: 01/14/2022] [Accepted: 01/17/2022] [Indexed: 12/02/2022] Open
Abstract
Arabidopsis LHP1 (LIKE HETEROCHROMATIN PROTEIN 1), a unique homolog of HP1 in Drosophila, plays important roles in plant development, growth, and architecture. In contrast to specific binding of the HP1 chromodomain to methylated H3K9 histone tails, the chromodomain of LHP1 has been shown to bind to both methylated H3K9 and H3K27 histone tails, and LHP1 carries out its function mainly via its interaction with these two epigenetic marks. However, the molecular mechanism for the recognition of methylated histone H3K9/27 by the LHP1 chromodomain is still unknown. In this study, we characterized the binding ability of LHP1 to histone H3K9 and H3K27 peptides and found that the chromodomain of LHP1 binds to histone H3K9me2/3 and H3K27me2/3 peptides with comparable affinities, although it exhibited no binding or weak binding to unmodified or monomethylated H3K9/K27 peptides. Our crystal structures of the LHP1 chromodomain in peptide-free and peptide-bound forms coupled with mutagenesis studies reveal that the chromodomain of LHP1 bears a slightly different chromodomain architecture and recognizes methylated H3K9 and H3K27 peptides via a hydrophobic clasp, similar to the chromodomains of human Polycomb proteins, which could not be explained only based on primary structure analysis. Our binding and structural studies of the LHP1 chromodomain illuminate a conserved ligand interaction mode between chromodomains of both animals and plants, and shed light on further functional study of the LHP1 protein.
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Affiliation(s)
- Yanli Liu
- College of Pharmaceutical Sciences, Soochow University, Su Zhou, Jiangsu 215021, PR China.
| | - Xiajie Yang
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, Hubei 430079, PR China
| | - Mengqi Zhou
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, Hubei 430079, PR China
| | - Yinxue Yang
- College of Pharmaceutical Sciences, Soochow University, Su Zhou, Jiangsu 215021, PR China
| | - Fangzhou Li
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, Hubei 430079, PR China
| | - Xuemei Yan
- College of Pharmaceutical Sciences, Soochow University, Su Zhou, Jiangsu 215021, PR China
| | | | - Zhengguo Wei
- School of Biology and Basic Medical Science, Soochow University, Su Zhou, Jiangsu 215021, PR China
| | - Su Qin
- Life Science Research Center, Southern University of Science and Technology, Shenzhen, Guangdong 518055, PR China
| | - Jinrong Min
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, Hubei 430079, PR China.
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12
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Lamb KN, Dishman SN, Waybright JM, Engelberg IA, Rectenwald JM, Norris-Drouin JL, Cholensky SH, Pearce KH, James LI, Frye SV. Discovery of Potent Peptidomimetic Antagonists for Heterochromatin Protein 1 Family Proteins. ACS OMEGA 2022; 7:716-732. [PMID: 35036738 PMCID: PMC8757366 DOI: 10.1021/acsomega.1c05381] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Accepted: 12/07/2021] [Indexed: 06/14/2023]
Abstract
The heterochromatin protein 1 (HP1) sub-family of CBX chromodomains are responsible for the recognition of histone H3 lysine 9 tri-methyl (H3K9me3)-marked nucleosomal substrates through binding of the N-terminal chromodomain. These HP1 proteins, namely, CBX1 (HP1β), CBX3 (HP1γ), and CBX5 (HP1α), are commonly associated with regions of pericentric heterochromatin, but recent literature studies suggest that regulation by these proteins is likely more dynamic and includes other loci. Importantly, there are no chemical tools toward HP1 chromodomains to spatiotemporally explore the effects of HP1-mediated processes, underscoring the need for novel HP1 chemical probes. Here, we report the discovery of HP1 targeting peptidomimetic compounds, UNC7047 and UNC7560, and a biotinylated derivative tool compound, UNC7565. These compounds represent an important milestone, as they possess nanomolar affinity for the CBX5 chromodomain by isothermal titration calorimetry (ITC) and bind HP1-containing complexes in cell lysates. These chemical tools provide a starting point for further optimization and the study of CBX5-mediated processes.
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Affiliation(s)
- Kelsey N. Lamb
- 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
| | - Sarah N. Dishman
- 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
| | - Jarod M. Waybright
- 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
| | - 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
| | - Justin M. Rectenwald
- 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
| | - 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
| | - Kenneth H. Pearce
- 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
| | - 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
| | - 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
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13
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Kulyyassov A. Application of Skyline for Analysis of Protein-Protein Interactions In Vivo. Molecules 2021; 26:molecules26237170. [PMID: 34885753 PMCID: PMC8658920 DOI: 10.3390/molecules26237170] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Revised: 11/22/2021] [Accepted: 11/23/2021] [Indexed: 11/19/2022] Open
Abstract
Quantitative and qualitative analyses of cell protein composition using liquid chromatography/tandem mass spectrometry are now standard techniques in biological and clinical research. However, the quantitative analysis of protein–protein interactions (PPIs) in cells is also important since these interactions are the bases of many processes, such as the cell cycle and signaling pathways. This paper describes the application of Skyline software for the identification and quantification of the biotinylated form of the biotin acceptor peptide (BAP) tag, which is a marker of in vivo PPIs. The tag was used in the Proximity Utilizing Biotinylation (PUB) method, which is based on the co-expression of BAP-X and BirA-Y in mammalian cells, where X or Y are interacting proteins of interest. A high level of biotinylation was detected in the model experiments where X and Y were pluripotency transcription factors Sox2 and Oct4, or heterochromatin protein HP1γ. MRM data processed by Skyline were normalized and recalculated. Ratios of biotinylation levels in experiment versus controls were 86 ± 6 (3 h biotinylation time) and 71 ± 5 (9 h biotinylation time) for BAP-Sox2 + BirA-Oct4 and 32 ± 3 (4 h biotinylation time) for BAP-HP1γ + BirA-HP1γ experiments. Skyline can also be applied for the analysis and identification of PPIs from shotgun proteomics data downloaded from publicly available datasets and repositories.
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Affiliation(s)
- Arman Kulyyassov
- Republican State Enterprise "National Center for Biotechnology" under the Science Committee of Ministry of Education and Science of the Republic of Kazakhstan, 13/5, Kurgalzhynskoye Road, Nur-Sultan 010000, Kazakhstan
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14
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Polycomb condensates can promote epigenetic marks but are not required for sustained chromatin compaction. Nat Commun 2021; 12:5888. [PMID: 34620850 PMCID: PMC8497513 DOI: 10.1038/s41467-021-26147-5] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Accepted: 09/15/2021] [Indexed: 12/28/2022] Open
Abstract
Organization of the genome into transcriptionally active euchromatin and silenced heterochromatin is essential for eukaryotic cell function. Phase-separation has been implicated in heterochromatin formation, but it is unclear how phase-separated condensates can contribute to stable repression, particularly for heritable epigenetic changes. Polycomb complex PRC1 is key for heterochromatin formation, but the multitude of Polycomb proteins has hindered our understanding of their collective contribution to chromatin repression. Here, we show that PRC1 forms multicomponent condensates through hetero-oligomerization. They preferentially seed at H3K27me3 marks, and subsequently write H2AK119Ub marks. We show that inducing Polycomb phase-separation can cause chromatin compaction, but polycomb condensates are dispensable for maintenance of the compacted state. Our data and simulations are consistent with a model in which the time integral of Polycomb phase-separation is progressively recorded in repressive histone marks, which subsequently drive compaction. These findings link the equilibrium thermodynamics of phase-separation with the fundamentally non-equilibrium concept of epigenetic memory. Phase separation has been suggested as a mechanism for heterochromatin formation through condensation of heterochromatin-associated factors. Here the authors show Polycomb complex PRC1 forms condensates on chromatin. Using optogenetic tools they nucleate local Polycomb condensates to show that this phase separation leads to subsequent histone modifications and chromatin compaction.
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15
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Qin W, Ugur E, Mulholland CB, Bultmann S, Solovei I, Modic M, Smets M, Wierer M, Forné I, Imhof A, Cardoso MC, Leonhardt H. Phosphorylation of the HP1β hinge region sequesters KAP1 in heterochromatin and promotes the exit from naïve pluripotency. Nucleic Acids Res 2021; 49:7406-7423. [PMID: 34214177 PMCID: PMC8287961 DOI: 10.1093/nar/gkab548] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 05/31/2021] [Accepted: 06/11/2021] [Indexed: 12/26/2022] Open
Abstract
Heterochromatin binding protein HP1β plays an important role in chromatin organization and cell differentiation, however the underlying mechanisms remain unclear. Here, we generated HP1β−/− embryonic stem cells and observed reduced heterochromatin clustering and impaired differentiation. We found that during stem cell differentiation, HP1β is phosphorylated at serine 89 by CK2, which creates a binding site for the pluripotency regulator KAP1. This phosphorylation dependent sequestration of KAP1 in heterochromatin compartments causes a downregulation of pluripotency factors and triggers pluripotency exit. Accordingly, HP1β−/− and phospho-mutant cells exhibited impaired differentiation, while ubiquitination-deficient KAP1−/− cells had the opposite phenotype with enhanced differentiation. These results suggest that KAP1 regulates pluripotency via its ubiquitination activity. We propose that the formation of subnuclear membraneless heterochromatin compartments may serve as a dynamic reservoir to trap or release cellular factors. The sequestration of essential regulators defines a novel and active role of heterochromatin in gene regulation and represents a dynamic mode of remote control to regulate cellular processes like cell fate decisions.
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Affiliation(s)
- Weihua Qin
- Faculty of Biology, Ludwig-Maximilians-Universität München, Butenandtstraße 1, D-81377 Munich, Germany
| | - Enes Ugur
- Faculty of Biology, Ludwig-Maximilians-Universität München, Butenandtstraße 1, D-81377 Munich, Germany.,Department of Proteomics and Signal Transduction, Max Planck Institute for Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany
| | - Christopher B Mulholland
- Faculty of Biology, Ludwig-Maximilians-Universität München, Butenandtstraße 1, D-81377 Munich, Germany
| | - Sebastian Bultmann
- Faculty of Biology, Ludwig-Maximilians-Universität München, Butenandtstraße 1, D-81377 Munich, Germany
| | - Irina Solovei
- Faculty of Biology, Ludwig-Maximilians-Universität München, Butenandtstraße 1, D-81377 Munich, Germany
| | - Miha Modic
- The Francis Crick Institute and UCL Queen Square Institute of Neurology, London NW1 1AT, United Kingdom
| | - Martha Smets
- Faculty of Biology, Ludwig-Maximilians-Universität München, Butenandtstraße 1, D-81377 Munich, Germany
| | - Michael Wierer
- Department of Proteomics and Signal Transduction, Max Planck Institute for Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany
| | - Ignasi Forné
- Biomedical Center Munich, Faculty of Medicine, Ludwig-Maximilians-Universität München, Großhaderner Str. 9, 82152 Planegg-Martinsried, Germany
| | - Axel Imhof
- Biomedical Center Munich, Faculty of Medicine, Ludwig-Maximilians-Universität München, Großhaderner Str. 9, 82152 Planegg-Martinsried, Germany
| | - M Cristina Cardoso
- Cell Biology and Epigenetics, Department of Biology, Technical University of Darmstadt, 64287 Darmstadt, Germany
| | - Heinrich Leonhardt
- Faculty of Biology, Ludwig-Maximilians-Universität München, Butenandtstraße 1, D-81377 Munich, Germany
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16
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Liyakat Ali TM, Brunet A, Collas P, Paulsen J. TAD cliques predict key features of chromatin organization. BMC Genomics 2021; 22:499. [PMID: 34217222 PMCID: PMC8254932 DOI: 10.1186/s12864-021-07815-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Accepted: 06/17/2021] [Indexed: 01/03/2023] Open
Abstract
BACKGROUND Mechanisms underlying genome 3D organization and domain formation in the mammalian nucleus are not completely understood. Multiple processes such as transcriptional compartmentalization, DNA loop extrusion and interactions with the nuclear lamina dynamically act on chromatin at multiple levels. Here, we explore long-range interaction patterns between topologically associated domains (TADs) in several cell types. RESULTS We find that TAD long-range interactions are connected to many key features of chromatin organization, including open and closed compartments, compaction and loop extrusion processes. Domains that form large TAD cliques tend to be repressive across cell types, when comparing gene expression, LINE/SINE repeat content and chromatin subcompartments. Further, TADs in large cliques are larger in genomic size, less dense and depleted of convergent CTCF motifs, in contrast to smaller and denser TADs formed by a loop extrusion process. CONCLUSIONS Our results shed light on the organizational principles that govern repressive and active domains in the human genome.
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Affiliation(s)
- Tharvesh M Liyakat Ali
- Department of Molecular Medicine, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, Oslo, Norway
| | - Annaël Brunet
- Department of Molecular Medicine, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, Oslo, Norway
| | - Philippe Collas
- Department of Molecular Medicine, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, Oslo, Norway.
- Department of Immunology and Transfusion Medicine, Oslo University Hospital, Oslo, Norway.
| | - Jonas Paulsen
- Institute of Biosciences, Faculty of Mathematics and Natural Sciences, University of Oslo, Oslo, Norway.
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17
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Casale AM, Cappucci U, Piacentini L. Unravelling HP1 functions: post-transcriptional regulation of stem cell fate. Chromosoma 2021; 130:103-111. [PMID: 34128099 PMCID: PMC8426308 DOI: 10.1007/s00412-021-00760-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Revised: 05/17/2021] [Accepted: 06/01/2021] [Indexed: 12/20/2022]
Abstract
Heterochromatin protein 1 (HP1) is a non-histone chromosomal protein first identified in Drosophila as a major component of constitutive heterochromatin, required for stable epigenetic gene silencing in many species including humans. Over the years, several studies have highlighted additional roles of HP1 in different cellular processes including telomere maintenance, DNA replication and repair, chromosome segregation and, surprisingly, positive regulation of gene expression. In this review, we briefly summarize past research and recent results supporting the unexpected and emerging role of HP1 in activating gene expression. In particular, we discuss the role of HP1 in post-transcriptional regulation of mRNA processing because it has proved decisive in the control of germline stem cells homeostasis in Drosophila and has certainly added a new dimension to our understanding on HP1 targeting and functions in epigenetic regulation of stem cell behaviour.
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Affiliation(s)
- Assunta Maria Casale
- Department of Biology and Biotechnology "C. Darwin", Sapienza University of Rome, Rome, Italy.
| | - Ugo Cappucci
- Department of Biology and Biotechnology "C. Darwin", Sapienza University of Rome, Rome, Italy
| | - Lucia Piacentini
- Department of Biology and Biotechnology "C. Darwin", Sapienza University of Rome, Rome, Italy.
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18
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Latham AP, Zhang B. Consistent Force Field Captures Homologue-Resolved HP1 Phase Separation. J Chem Theory Comput 2021; 17:3134-3144. [PMID: 33826337 PMCID: PMC8119372 DOI: 10.1021/acs.jctc.0c01220] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Many proteins have been shown to function via liquid-liquid phase separation. Computational modeling could offer much needed structural details of protein condensates and reveal the set of molecular interactions that dictate their stability. However, the presence of both ordered and disordered domains in these proteins places a high demand on the model accuracy. Here, we present an algorithm to derive a coarse-grained force field, MOFF, which can model both ordered and disordered proteins with consistent accuracy. It combines maximum entropy biasing, least-squares fitting, and basic principles of energy landscape theory to ensure that MOFF recreates experimental radii of gyration while predicting the folded structures for globular proteins with lower energy. The theta temperature determined from MOFF separates ordered and disordered proteins at 300 K and exhibits a strikingly linear relationship with amino acid sequence composition. We further applied MOFF to study the phase behavior of HP1, an essential protein for post-translational modification and spatial organization of chromatin. The force field successfully resolved the structural difference of two HP1 homologues despite their high sequence similarity. We carried out large-scale simulations with hundreds of proteins to determine the critical temperature of phase separation and uncover multivalent interactions that stabilize higher-order assemblies. In all, our work makes significant methodological strides to connect theories of ordered and disordered proteins and provides a powerful tool for studying liquid-liquid phase separation with near-atomistic details.
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Affiliation(s)
- Andrew P Latham
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Bin Zhang
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
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19
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Zhang C, Cheng Q, Wang H, Gao H, Fang X, Chen X, Zhao M, Wei W, Song B, Liu S, Wu J, Zhang S, Xu P. GmBTB/POZ promotes the ubiquitination and degradation of LHP1 to regulate the response of soybean to Phytophthora sojae. Commun Biol 2021; 4:372. [PMID: 33742112 PMCID: PMC7979691 DOI: 10.1038/s42003-021-01907-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2019] [Accepted: 02/24/2021] [Indexed: 01/07/2023] Open
Abstract
Phytophthora sojae is a pathogen that causes stem and root rot in soybean (Glycine max [L.] Merr.). We previously demonstrated that GmBTB/POZ, a BTB/POZ domain-containing nuclear protein, enhances resistance to P. sojae in soybean, via a process that depends on salicylic acid (SA). Here, we demonstrate that GmBTB/POZ associates directly with soybean LIKE HETEROCHROMATIN PROTEIN1 (GmLHP1) in vitro and in vivo and promotes its ubiquitination and degradation. Both overexpression and RNA interference analysis of transgenic lines demonstrate that GmLHP1 negatively regulates the response of soybean to P. sojae by reducing SA levels and repressing GmPR1 expression. The WRKY transcription factor gene, GmWRKY40, a SA-induced gene in the SA signaling pathway, is targeted by GmLHP1, which represses its expression via at least two mechanisms (directly binding to its promoter and impairing SA accumulation). Furthermore, the nuclear localization of GmLHP1 is required for the GmLHP1-mediated negative regulation of immunity, SA levels and the suppression of GmWRKY40 expression. Finally, GmBTB/POZ releases GmLHP1-regulated GmWRKY40 suppression and increases resistance to P. sojae in GmLHP1-OE hairy roots. These findings uncover a regulatory mechanism by which GmBTB/POZ-GmLHP1 modulates resistance to P. sojae in soybean, likely by regulating the expression of downstream target gene GmWRKY40.
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Affiliation(s)
- Chuanzhong Zhang
- Soybean Research Institute, Northeast Agricultural University, Key Laboratory of Soybean Biology of Chinese Education Ministry, Harbin, China
- Key Laboratory of Soybean Molecular Design Breeding, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Harbin, China
| | - Qun Cheng
- Soybean Research Institute, Northeast Agricultural University, Key Laboratory of Soybean Biology of Chinese Education Ministry, Harbin, China
| | - Huiyu Wang
- Soybean Research Institute, Northeast Agricultural University, Key Laboratory of Soybean Biology of Chinese Education Ministry, Harbin, China
| | - Hong Gao
- Soybean Research Institute, Northeast Agricultural University, Key Laboratory of Soybean Biology of Chinese Education Ministry, Harbin, China
| | - Xin Fang
- Soybean Research Institute, Northeast Agricultural University, Key Laboratory of Soybean Biology of Chinese Education Ministry, Harbin, China
| | - Xi Chen
- Soybean Research Institute, Northeast Agricultural University, Key Laboratory of Soybean Biology of Chinese Education Ministry, Harbin, China
| | - Ming Zhao
- Soybean Research Institute, Northeast Agricultural University, Key Laboratory of Soybean Biology of Chinese Education Ministry, Harbin, China
| | - Wanling Wei
- Soybean Research Institute, Northeast Agricultural University, Key Laboratory of Soybean Biology of Chinese Education Ministry, Harbin, China
| | - Bo Song
- Soybean Research Institute, Northeast Agricultural University, Key Laboratory of Soybean Biology of Chinese Education Ministry, Harbin, China
| | - Shanshan Liu
- Soybean Research Institute, Northeast Agricultural University, Key Laboratory of Soybean Biology of Chinese Education Ministry, Harbin, China
| | - Junjiang Wu
- Soybean Research Institute of Heilongjiang Academy of Agricultural Sciences, Key Laboratory of Soybean Cultivation of Ministry of Agriculture, Harbin, China
| | - Shuzhen Zhang
- Soybean Research Institute, Northeast Agricultural University, Key Laboratory of Soybean Biology of Chinese Education Ministry, Harbin, China.
| | - Pengfei Xu
- Soybean Research Institute, Northeast Agricultural University, Key Laboratory of Soybean Biology of Chinese Education Ministry, Harbin, China.
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20
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Qin W, Stengl A, Ugur E, Leidescher S, Ryan J, Cardoso MC, Leonhardt H. HP1β carries an acidic linker domain and requires H3K9me3 for phase separation. Nucleus 2021; 12:44-57. [PMID: 33660589 PMCID: PMC7939559 DOI: 10.1080/19491034.2021.1889858] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Liquid-liquid phase separation (LLPS) mediated formation of membraneless organelles has been proposed to coordinate biological processes in space and time. Previously, the formation of phase-separated droplets was described as a unique property of HP1α. Here, we demonstrate that the positive net charge of the intrinsically disordered hinge region (IDR-H) of HP1 proteins is critical for phase separation and that the exchange of four acidic amino acids is sufficient to confer LLPS properties to HP1β. Surprisingly, the addition of mono-nucleosomes promoted H3K9me3-dependent LLPS of HP1β which could be specifically disrupted with methylated but not acetylated H3K9 peptides. HP1β mutants defective in H3K9me3 binding were less efficient in phase separationin vitro and failed to accumulate at heterochromatin in vivo. We propose that multivalent interactions of HP1β with H3K9me3-modified nucleosomes via its chromodomain and dimerization via its chromoshadow domain enable phase separation and contribute to the formation of heterochromatin compartments in vivo.
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Affiliation(s)
- Weihua Qin
- Center for Molecular Biosystems (BioSysM), Faculty of Biology, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Andreas Stengl
- Center for Molecular Biosystems (BioSysM), Faculty of Biology, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Enes Ugur
- Center for Molecular Biosystems (BioSysM), Faculty of Biology, Ludwig-Maximilians-Universität München, Munich, Germany.,Department of Proteomics and Signal Transduction, Max Planck Institute for Biochemistry, Martinsried, Germany
| | - Susanne Leidescher
- Center for Molecular Biosystems (BioSysM), Faculty of Biology, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Joel Ryan
- Center for Molecular Biosystems (BioSysM), Faculty of Biology, Ludwig-Maximilians-Universität München, Munich, Germany
| | - M Cristina Cardoso
- Cell Biology and Epigenetics, Department of Biology, Technical University of Darmstadt, Darmstadt, Germany
| | - Heinrich Leonhardt
- Center for Molecular Biosystems (BioSysM), Faculty of Biology, Ludwig-Maximilians-Universität München, Munich, Germany
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21
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Sun J, Wang X, Xu RG, Mao D, Shen D, Wang X, Qiu Y, Han Y, Lu X, Li Y, Che Q, Zheng L, Peng P, Kang X, Zhu R, Jia Y, Wang Y, Liu LP, Chang Z, Ji JY, Wang Z, Liu Q, Li S, Sun FL, Ni JQ. HP1c regulates development and gut homeostasis by suppressing Notch signaling through Su(H). EMBO Rep 2021; 22:e51298. [PMID: 33594776 DOI: 10.15252/embr.202051298] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Revised: 01/01/2021] [Accepted: 01/13/2021] [Indexed: 12/30/2022] Open
Abstract
Notch signaling and epigenetic factors are known to play critical roles in regulating tissue homeostasis in most multicellular organisms, but how Notch signaling coordinates with epigenetic modulators to control differentiation remains poorly understood. Here, we identify heterochromatin protein 1c (HP1c) as an essential epigenetic regulator of gut homeostasis in Drosophila. Specifically, we observe that HP1c loss-of-function phenotypes resemble those observed after Notch signaling perturbation and that HP1c interacts genetically with components of the Notch pathway. HP1c represses the transcription of Notch target genes by directly interacting with Suppressor of Hairless (Su(H)), the key transcription factor of Notch signaling. Moreover, phenotypes caused by depletion of HP1c in Drosophila can be rescued by expressing human HP1γ, suggesting that HP1γ functions similar to HP1c in Drosophila. Taken together, our findings reveal an essential role of HP1c in normal development and gut homeostasis by suppressing Notch signaling.
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Affiliation(s)
- Jin Sun
- Gene Regulatory Lab, School of Medicine, Tsinghua University, Beijing, China.,Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, China
| | - Xia Wang
- Gene Regulatory Lab, School of Medicine, Tsinghua University, Beijing, China.,School of Life Sciences, Peking University, Beijing, China
| | - Rong-Gang Xu
- Gene Regulatory Lab, School of Medicine, Tsinghua University, Beijing, China
| | - Decai Mao
- Gene Regulatory Lab, School of Medicine, Tsinghua University, Beijing, China.,Sichuan Academy of Grassland Science, Chengdu, China
| | - Da Shen
- Gene Regulatory Lab, School of Medicine, Tsinghua University, Beijing, China
| | - Xin Wang
- Institute for TCM-X, MOE Key Laboratory of Bioinformatics/Bioinformatics Division, BNRIST, Department of Automation, Tsinghua University, Beijing, China
| | - Yuhao Qiu
- Gene Regulatory Lab, School of Medicine, Tsinghua University, Beijing, China.,Tsinghua University-Peking University Joint Center for Life Sciences, Beijing, China
| | - Yuting Han
- Gene Regulatory Lab, School of Medicine, Tsinghua University, Beijing, China
| | - Xinyi Lu
- Gene Regulatory Lab, School of Medicine, Tsinghua University, Beijing, China
| | - Yutong Li
- Gene Regulatory Lab, School of Medicine, Tsinghua University, Beijing, China
| | - Qinyun Che
- Gene Regulatory Lab, School of Medicine, Tsinghua University, Beijing, China
| | - Li Zheng
- Gene Regulatory Lab, School of Medicine, Tsinghua University, Beijing, China
| | - Ping Peng
- Gene Regulatory Lab, School of Medicine, Tsinghua University, Beijing, China.,Tsinghua University-Peking University Joint Center for Life Sciences, Beijing, China
| | - Xuan Kang
- Research Center for Translational Medicine at East Hospital, School of Life Sciences and Technology, Advanced Institute of Translational Medicine, Tongji University, Shanghai, China
| | - Ruibao Zhu
- Gene Regulatory Lab, School of Medicine, Tsinghua University, Beijing, China.,Tsinghua University-Peking University Joint Center for Life Sciences, Beijing, China
| | - Yu Jia
- Gene Regulatory Lab, School of Medicine, Tsinghua University, Beijing, China.,Tsinghua University-Peking University Joint Center for Life Sciences, Beijing, China
| | - Yinyin Wang
- State Key Laboratory of Membrane Biology, School of Medicine and the School of Life Sciences, Tsinghua University, Beijing, China
| | - Lu-Ping Liu
- Gene Regulatory Lab, School of Medicine, Tsinghua University, Beijing, China
| | - Zhijie Chang
- State Key Laboratory of Membrane Biology, School of Medicine and the School of Life Sciences, Tsinghua University, Beijing, China
| | - Jun-Yuan Ji
- Department of Molecular and Cellular Medicine, College of Medicine, Texas A&M Health Science Center, College Station, TX, USA
| | - Zhao Wang
- School of Pharmaceutical Sciences, Tsinghua University, Beijing, China
| | - Qingfei Liu
- School of Pharmaceutical Sciences, Tsinghua University, Beijing, China
| | - Shao Li
- Institute for TCM-X, MOE Key Laboratory of Bioinformatics/Bioinformatics Division, BNRIST, Department of Automation, Tsinghua University, Beijing, China
| | - Fang-Lin Sun
- Research Center for Translational Medicine at East Hospital, School of Life Sciences and Technology, Advanced Institute of Translational Medicine, Tongji University, Shanghai, China
| | - Jian-Quan Ni
- Gene Regulatory Lab, School of Medicine, Tsinghua University, Beijing, China.,Tsingdao Advanced Research Institute, Tongji University, Qingdao, China
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22
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Sikder S, Kaypee S, Kundu TK. Regulation of epigenetic state by non-histone chromatin proteins and transcription factors: Implications in disease. J Biosci 2020. [DOI: 10.1007/s12038-019-9974-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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23
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Pokorná P, Krepl M, Šponer J. Residues flanking the ARK me3T/S motif allow binding of diverse targets to the HP1 chromodomain: Insights from molecular dynamics simulations. Biochim Biophys Acta Gen Subj 2020; 1865:129771. [PMID: 33153976 DOI: 10.1016/j.bbagen.2020.129771] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 09/15/2020] [Accepted: 10/20/2020] [Indexed: 11/28/2022]
Abstract
BACKGROUND The chromodomain (CD) of HP1 proteins is an established H3K9me3 reader that also binds H1, EHMT2 and H3K23 lysine-methylated targets. Structural experiments have provided atomistic pictures of its recognition of the conserved ARKme3S/T motif, but structural dynamics' contribution to the recognition may have been masked by ensemble averaging. METHODS We acquired ~350 μs of explicit solvent molecular dynamics (MD) simulations of the CD domain interacting with several peptides using the latest AMBER force fields. RESULTS The simulations reproduced the experimentally observed static binding patterns well but also revealed visible structural dynamics at the interfaces. While the buried K0me3 and A-2 target residues are tightly bound, several flanking sidechains sample diverse sites on the CD surface. Different amino acid positions of the targets can substitute for each other by forming mutually replaceable interactions with CD, thereby explaining the lack of strict requirement for cationic H3 target residues at the -3 position. The Q-4 residue of H3 targets further stabilizes the binding. The recognition pattern of the H3K23 ATKme3A motif, for which no structure is available, is predicted. CONCLUSIONS The CD reads a longer target segment than previously thought, ranging from positions -7 to +3. The CD anionic clamp can be neutralized not only by the -3 and -1 residues, but also by -7, -6, -5 and +3 residues. GENERAL SIGNIFICANCE Structural dynamics, not immediately apparent from the structural data, contribute to molecular recognition between the HP1 CD domain and its targets. Mutual replaceability of target residues increases target sequence flexibility.
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Affiliation(s)
- Pavlína Pokorná
- Institute of Biophysics of the Czech Academy of Sciences, Královopolská 135, 612 65 Brno, Czech Republic; National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kamenice 5, 625 00 Brno, Czech Republic.
| | - Miroslav Krepl
- Institute of Biophysics of the Czech Academy of Sciences, Královopolská 135, 612 65 Brno, Czech Republic
| | - Jiří Šponer
- Institute of Biophysics of the Czech Academy of Sciences, Královopolská 135, 612 65 Brno, Czech Republic.
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24
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Meyer-Nava S, Nieto-Caballero VE, Zurita M, Valadez-Graham V. Insights into HP1a-Chromatin Interactions. Cells 2020; 9:E1866. [PMID: 32784937 PMCID: PMC7465937 DOI: 10.3390/cells9081866] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Revised: 07/18/2020] [Accepted: 07/21/2020] [Indexed: 12/17/2022] Open
Abstract
Understanding the packaging of DNA into chromatin has become a crucial aspect in the study of gene regulatory mechanisms. Heterochromatin establishment and maintenance dynamics have emerged as some of the main features involved in genome stability, cellular development, and diseases. The most extensively studied heterochromatin protein is HP1a. This protein has two main domains, namely the chromoshadow and the chromodomain, separated by a hinge region. Over the years, several works have taken on the task of identifying HP1a partners using different strategies. In this review, we focus on describing these interactions and the possible complexes and subcomplexes associated with this critical protein. Characterization of these complexes will help us to clearly understand the implications of the interactions of HP1a in heterochromatin maintenance, heterochromatin dynamics, and heterochromatin's direct relationship to gene regulation and chromatin organization.
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Affiliation(s)
| | | | | | - Viviana Valadez-Graham
- Instituto de Biotecnología, Departamento de Genética del Desarrollo y Fisiología Molecular, Universidad Nacional Autónoma de México, Cuernavaca Morelos 62210, Mexico; (S.M.-N.); (V.E.N.-C.); (M.Z.)
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25
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Charaka V, Tiwari A, Pandita RK, Hunt CR, Pandita TK. Role of HP1β during spermatogenesis and DNA replication. Chromosoma 2020; 129:215-226. [PMID: 32651609 DOI: 10.1007/s00412-020-00739-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Revised: 06/28/2020] [Accepted: 06/29/2020] [Indexed: 11/25/2022]
Abstract
Heterochromatin protein 1β (HP1β), encoded by the Cbx1 gene, has been functionally linked to chromatin condensation, transcriptional regulation, and DNA damage repair. Here we report that testis-specific Cbx1 conditional knockout (Cbx1 cKO) impairs male germ cell development in mice. Depletion of HP1β negatively affected sperm maturation and increased seminiferous tubule degeneration in Cbx1 cKO mice. In addition, the spermatogonia have elevated γ-H2AX foci levels as do Cbx1 deficient mouse embryonic fibroblasts (MEFs) as compared to wild-type (WT) control MEFs. The increase in γ-H2AX foci in proliferating Cbx1 cKO cells indicates defective replication-dependent DNA damage repair. Depletion or loss of HP1β from human cells and MEFs increased DNA replication fork stalling and firing of new origins of replication, indicating defective DNA synthesis. Taken together, these results suggest that loss of HP1β in proliferating cells leads to DNA replication defects with associated DNA damage that impact spermatogenesis.
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Affiliation(s)
- Vijay Charaka
- Department of Radiation Oncology, The Houston Methodist Research Institute, Houston, TX, 77030, USA
| | - Anjana Tiwari
- Department of Radiation Oncology, The Houston Methodist Research Institute, Houston, TX, 77030, USA
| | - Raj K Pandita
- Department of Radiation Oncology, The Houston Methodist Research Institute, Houston, TX, 77030, USA
- Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Clayton R Hunt
- Department of Radiation Oncology, The Houston Methodist Research Institute, Houston, TX, 77030, USA
| | - Tej K Pandita
- Department of Radiation Oncology, The Houston Methodist Research Institute, Houston, TX, 77030, USA.
- Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, 77030, USA.
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26
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Meyer-Nava S, Torres A, Zurita M, Valadez-Graham V. Molecular effects of dADD1 misexpression in chromatin organization and transcription. BMC Mol Cell Biol 2020; 21:17. [PMID: 32293240 PMCID: PMC7092677 DOI: 10.1186/s12860-020-00257-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Accepted: 03/04/2020] [Indexed: 12/14/2022] Open
Abstract
Background dADD1 and dXNP proteins are the orthologs in Drosophila melanogaster of the ADD and SNF2 domains, respectively, of the ATRX vertebrate’s chromatin remodeler, they suppress position effect variegation phenotypes and participate in heterochromatin maintenance. Results We performed a search in human cancer databases and found that ATRX protein levels were elevated in more than 4.4% of the samples analyzed. Using the Drosophila model, we addressed the effects of over and under-expression of dADD1 proteins in polytene cells. Elevated levels of dADD1 in fly tissues caused different phenotypes, such as chromocenter disruption and loss of banding pattern at the chromosome arms. Analyses of the heterochromatin maintenance protein HP1a, the dXNP ATPase and the histone post-translational modification H3K9me3 revealed changes in their chromatin localization accompanied by mild transcriptional defects of genes embedded in heterochromatic regions. Furthermore, the expression of heterochromatin embedded genes in null dadd1 organisms is lower than in the wild-type conditions. Conclusion These data indicate that dADD1 overexpression induces chromatin changes, probably affecting the stoichiometry of HP1a containing complexes that lead to transcriptional and architectural changes. Our results place dADD1 proteins as important players in the maintenance of chromatin architecture and heterochromatic gene expression.
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Affiliation(s)
- Silvia Meyer-Nava
- Instituto de Biotecnología. Universidad Nacional Autónoma de México, Campus Morelos, Av. Universidad 2001, C.P, 62210, Cuernavaca, Morelos, Mexico
| | - Amada Torres
- Instituto de Biotecnología. Universidad Nacional Autónoma de México, Campus Morelos, Av. Universidad 2001, C.P, 62210, Cuernavaca, Morelos, Mexico
| | - Mario Zurita
- Instituto de Biotecnología. Universidad Nacional Autónoma de México, Campus Morelos, Av. Universidad 2001, C.P, 62210, Cuernavaca, Morelos, Mexico
| | - Viviana Valadez-Graham
- Instituto de Biotecnología. Universidad Nacional Autónoma de México, Campus Morelos, Av. Universidad 2001, C.P, 62210, Cuernavaca, Morelos, Mexico.
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27
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Di Mauro G, Carbonell A, Escudero-Ferruz P, Azorín F. The zinc-finger proteins WOC and ROW play distinct functions within the HP1c transcription complex. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2020; 1863:194492. [PMID: 32006714 DOI: 10.1016/j.bbagrm.2020.194492] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Revised: 01/28/2020] [Accepted: 01/29/2020] [Indexed: 11/20/2022]
Abstract
In Drosophila, the Heterochromatin Protein 1c (HP1c) forms a transcriptional complex with the zinc-finger proteins WOC and ROW, and the extraproteasomal ubiquitin receptor Dsk2. This complex localizes at promoters of active genes and it is required for transcription. The functions played by the different components of the HP1c complex are not fully understood. In this study we show that WOC and ROW are required for chromatin binding of both Dsk2 and HP1c. However, while impairing chromatin binding strongly destabilizes HP1c, it does not affect Dsk2 stability. We also show that WOC, but not ROW, is required for nuclear localization of Dsk2. Moreover, WOC and Dsk2 co-immunoprecitate upon ROW depletion. These results suggest that WOC and Dsk2 interact to form a subcomplex that mediates nuclear translocation of Dsk2. We also show that ROW mediates chromatin binding of the WOC/Dsk2 subcomplex, as well as of HP1c. Altogether these observations favor a model by which the interaction with WOC recruits Dsk2 to the HP1c complex that, in its turn, binds chromatin in a ROW-dependent manner.
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Affiliation(s)
- Gianmarco Di Mauro
- Institute of Molecular Biology of Barcelona, CSIC, Baldiri Reixac, 10-12, 08028 Barcelona, Spain; Institute for Research in Biomedicine, IRB Barcelona, The Barcelona Institute for Science and Technology, Baldiri Reixac, 10-12, 08028 Barcelona, Spain
| | - Albert Carbonell
- Institute of Molecular Biology of Barcelona, CSIC, Baldiri Reixac, 10-12, 08028 Barcelona, Spain; Institute for Research in Biomedicine, IRB Barcelona, The Barcelona Institute for Science and Technology, Baldiri Reixac, 10-12, 08028 Barcelona, Spain
| | - Paula Escudero-Ferruz
- Institute of Molecular Biology of Barcelona, CSIC, Baldiri Reixac, 10-12, 08028 Barcelona, Spain; Institute for Research in Biomedicine, IRB Barcelona, The Barcelona Institute for Science and Technology, Baldiri Reixac, 10-12, 08028 Barcelona, Spain
| | - Fernando Azorín
- Institute of Molecular Biology of Barcelona, CSIC, Baldiri Reixac, 10-12, 08028 Barcelona, Spain; Institute for Research in Biomedicine, IRB Barcelona, The Barcelona Institute for Science and Technology, Baldiri Reixac, 10-12, 08028 Barcelona, Spain.
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28
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Wright GM, Cui F. The nucleosome position-encoding WW/SS sequence pattern is depleted in mammalian genes relative to other eukaryotes. Nucleic Acids Res 2019; 47:7942-7954. [PMID: 31216031 PMCID: PMC6735720 DOI: 10.1093/nar/gkz544] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Revised: 06/04/2019] [Accepted: 06/10/2019] [Indexed: 12/21/2022] Open
Abstract
Nucleosomal DNA sequences generally follow a well-known pattern with ∼10-bp periodic WW (where W is A or T) dinucleotides that oscillate in phase with each other and out of phase with SS (where S is G or C) dinucleotides. However, nucleosomes with other DNA patterns have not been systematically analyzed. Here, we focus on an opposite pattern, namely anti-WW/SS pattern, in which WW dinucleotides preferentially occur at DNA sites that bend into major grooves and SS (where S is G or C) dinucleotides are often found at sites that bend into minor grooves. Nucleosomes with the anti-WW/SS pattern are widespread and exhibit a species- and context-specific distribution in eukaryotic genomes. Unlike non-mammals (yeast, nematode and fly), there is a positive correlation between the enrichment of anti-WW/SS nucleosomes and RNA Pol II transcriptional levels in mammals (mouse and human). Interestingly, such enrichment is not due to underlying DNA sequence. In addition, chromatin remodeling complexes have an impact on the abundance but not on the distribution of anti-WW/SS nucleosomes in yeast. Our data reveal distinct roles of cis- and trans-acting factors in the rotational positioning of nucleosomes between non-mammals and mammals. Implications of the anti-WW/SS sequence pattern for RNA Pol II transcription are discussed.
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Affiliation(s)
- Gregory M Wright
- Thomas H. Gosnell School of Life Sciences, Rochester Institute of Technology, 85 Lomb Memorial Drive, Rochester, NY 14623, USA
| | - Feng Cui
- Thomas H. Gosnell School of Life Sciences, Rochester Institute of Technology, 85 Lomb Memorial Drive, Rochester, NY 14623, USA
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29
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Pokorná P, Krepl M, Bártová E, Šponer J. Role of Fine Structural Dynamics in Recognition of Histone H3 by HP1γ(CSD) Dimer and Ability of Force Fields to Describe Their Interaction Network. J Chem Theory Comput 2019; 15:5659-5673. [DOI: 10.1021/acs.jctc.9b00434] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Pavlína Pokorná
- Institute of Biophysics of the Czech Academy of Sciences, Královopolská 135, 612 65 Brno, Czech Republic
- National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kamenice 5, 625 00 Brno, Czech Republic
| | - Miroslav Krepl
- Institute of Biophysics of the Czech Academy of Sciences, Královopolská 135, 612 65 Brno, Czech Republic
| | - Eva Bártová
- Institute of Biophysics of the Czech Academy of Sciences, Královopolská 135, 612 65 Brno, Czech Republic
| | - Jiří Šponer
- Institute of Biophysics of the Czech Academy of Sciences, Královopolská 135, 612 65 Brno, Czech Republic
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30
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Williams MM, Mathison AJ, Christensen T, Greipp PT, Knutson DL, Klee EW, Zimmermann MT, Iovanna J, Lomberk GA, Urrutia RA. Aurora kinase B-phosphorylated HP1α functions in chromosomal instability. Cell Cycle 2019; 18:1407-1421. [PMID: 31130069 PMCID: PMC6592258 DOI: 10.1080/15384101.2019.1618126] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Revised: 04/17/2019] [Accepted: 05/08/2019] [Indexed: 01/25/2023] Open
Abstract
Heterochromatin Protein 1 α (HP1α) associates with members of the chromosome passenger complex (CPC) during mitosis, at centromeres where it is required for full Aurora Kinase B (AURKB) activity. Conversely, recent reports have identified AURKB as the major kinase responsible for phosphorylation of HP1α at Serine 92 (S92) during mitosis. Thus, the current study was designed to better understand the functional role of this posttranslationally modified form of HP1α. We find that S92-phosphorylated HP1α is generated in cells at early prophase, localizes to centromeres, and associates with regulators of chromosome stability, such as Inner Centromere Protein, INCENP. In mouse embryonic fibroblasts, HP1α knockout alone or reconstituted with a non-phosphorylatable (S92A) HP1α mutant results in mitotic chromosomal instability characterized by the formation of anaphase/telophase chromatin bridges and micronuclei. These effects are rescued by exogenous expression of wild type HP1α or a phosphomimetic (S92D) variant. Thus, the results from the current study extend our knowledge of the role of HP1α in chromosomal stability during mitosis.
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Affiliation(s)
- Monique M. Williams
- Departments of Biochemistry and Biostatistics, Mayo Clinic, Rochester, MN, USA
| | - Angela J. Mathison
- Genomics and Precision Medicine Center (GSPMC), Medical College of Wisconsin, Milwaukee, WI, USA
- Division of Research, Department of Surgery, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Trent Christensen
- Departments of Biochemistry and Biostatistics, Mayo Clinic, Rochester, MN, USA
| | - Patricia T. Greipp
- Medical Genome Facility, Cytogenetics Core Laboratory, Rochester, MN, USA
| | - Darlene L. Knutson
- Medical Genome Facility, Cytogenetics Core Laboratory, Rochester, MN, USA
| | - Eric W. Klee
- Departments of Biochemistry and Biostatistics, Mayo Clinic, Rochester, MN, USA
| | - Michael T. Zimmermann
- Bioinformatics Research and Development Laboratory, Genomics Sciences and Precision Medicine Center, Medical College of Wisconsin, Milwaukee, WI, USA
- Clinical and Translational Sciences Institute, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Juan Iovanna
- Centre de Recherche en Cancérologie de Marseille (CRCM), INSERM U1068, CNRS UMR 7258, Aix-Marseille Université and Institut Paoli-Calmettes, Parc Scientifique et Technologique de Luminy, Marseille, France
| | - Gwen A. Lomberk
- Genomics and Precision Medicine Center (GSPMC), Medical College of Wisconsin, Milwaukee, WI, USA
- Division of Research, Department of Surgery, Medical College of Wisconsin, Milwaukee, WI, USA
- Department of Pharmacology and Toxicology, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Raul A. Urrutia
- Genomics and Precision Medicine Center (GSPMC), Medical College of Wisconsin, Milwaukee, WI, USA
- Division of Research, Department of Surgery, Medical College of Wisconsin, Milwaukee, WI, USA
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, WI, USA
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31
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Shen KF, Forsburg SL. Overlapping Roles in Chromosome Segregation for Heterochromatin Protein 1 (Swi6) and DDK in Schizosaccharomyces pombe. Genetics 2019; 212:417-430. [PMID: 31000521 PMCID: PMC6553818 DOI: 10.1534/genetics.119.302125] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Accepted: 04/10/2019] [Indexed: 12/23/2022] Open
Abstract
Fission yeast Swi6 is a human HP1 homolog that plays important roles in multiple cellular processes. In addition to its role in maintaining heterochromatin silencing, Swi6 is required for cohesin enrichment at the pericentromere. Loss of Swi6 leads to abnormal mitosis, including defects in the establishment of bioriented sister kinetochores and microtubule attachment. Swi6 interacts with Dfp1, a regulatory subunit of DBF4-dependent kinase (DDK), and failure to recruit Dfp1 to the pericentromere results in late DNA replication. Using the dfp1-3A mutant allele, which specifically disrupts Swi6-Dfp1 association, we investigated how interaction between Swi6 and Dfp1 affects chromosome dynamics. We find that disrupting the interaction between Swi6 and Dfp1 delays mitotic progression in a spindle assembly checkpoint-dependent manner. Artificially tethering Dfp1 back to the pericentromere is sufficient to restore normal spindle length and rescue segregation defects in swi6-deleted cells. However, Swi6 is necessary for centromeric localization of Rad21-GFP independent of DDK. Our data indicate that DDK contributes to mitotic chromosome segregation in pathways that partly overlap with, but can be separated from both, Swi6 and the other HP1 homolog, Chp2.
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Affiliation(s)
- Kuo-Fang Shen
- Program in Molecular and Computational Biology, University of Southern California, Los Angeles, California 90089-2910
| | - Susan L Forsburg
- Program in Molecular and Computational Biology, University of Southern California, Los Angeles, California 90089-2910
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32
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Profiling of LINE-1-Related Genes in Hepatocellular Carcinoma. Int J Mol Sci 2019; 20:ijms20030645. [PMID: 30717368 PMCID: PMC6387036 DOI: 10.3390/ijms20030645] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2018] [Revised: 01/26/2019] [Accepted: 01/29/2019] [Indexed: 12/14/2022] Open
Abstract
Hepatocellular carcinoma (HCC) is a prime public health concern that accounts for most of the primary liver malignancies in humans. The most common etiological factor of HCC is hepatitis B virus (HBV). Despite recent advances in treatment strategies, there has been little success in improving the survival of HCC patients. To develop a novel therapeutic approach, evaluation of a working hypothesis based on different viewpoints might be important. Long interspersed element 1 (L1) retrotransposons have been suggested to play a role in HCC. However, the molecular machineries that can modulate L1 biology in HBV-related HCC have not been well-evaluated. Here, we summarize the profiles of expression and/or activation status of L1-related genes in HBV-related HCC, and HBV- and HCC-related genes that may impact L1-mediated tumorigenesis. L1 restriction factors appear to be suppressed by HBV infection. Since some of the L1 restriction factors also limit HBV, these factors may be exhausted in HBV-infected cells, which causes de-suppression of L1. Several HBV- and HCC-related genes that interact with L1 can affect oncogenic processes. Thus, L1 may be a novel prime therapeutic target for HBV-related HCC. Studies in this area will provide insights into HCC and other types of cancers.
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33
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Janssen A, Colmenares SU, Lee T, Karpen GH. Timely double-strand break repair and pathway choice in pericentromeric heterochromatin depend on the histone demethylase dKDM4A. Genes Dev 2018; 33:103-115. [PMID: 30578303 PMCID: PMC6317320 DOI: 10.1101/gad.317537.118] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Accepted: 10/29/2018] [Indexed: 12/22/2022]
Abstract
Repair of DNA double-strand breaks (DSBs) must be orchestrated properly within diverse chromatin domains in order to maintain genetic stability. Euchromatin and heterochromatin domains display major differences in histone modifications, biophysical properties, and spatiotemporal dynamics of DSB repair. However, it is unclear whether differential histone-modifying activities are required for DSB repair in these distinct domains. We showed previously that the Drosophila melanogaster KDM4A (dKDM4A) histone demethylase is required for heterochromatic DSB mobility. Here we used locus-specific DSB induction in Drosophila animal tissues and cultured cells to more deeply interrogate the impact of dKDM4A on chromatin changes, temporal progression, and pathway utilization during DSB repair. We found that dKDM4A promotes the demethylation of heterochromatin-associated histone marks at DSBs in heterochromatin but not euchromatin. Most importantly, we demonstrate that dKDM4A is required to complete DSB repair in a timely manner and regulate the relative utilization of homologous recombination (HR) and nonhomologous end-joining (NHEJ) repair pathways but exclusively for heterochromatic DSBs. We conclude that the temporal kinetics and pathway utilization during heterochromatic DSB repair depend on dKDM4A-dependent demethylation of heterochromatic histone marks. Thus, distinct pre-existing chromatin states require specialized epigenetic alterations to ensure proper DSB repair.
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Affiliation(s)
- Aniek Janssen
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.,Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, California 94720, USA.,Innovative Genomics Institute, Berkeley, California 94720, USA
| | - Serafin U Colmenares
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.,Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, California 94720, USA.,Innovative Genomics Institute, Berkeley, California 94720, USA
| | - Timothy Lee
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.,Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, California 94720, USA
| | - Gary H Karpen
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.,Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, California 94720, USA.,Innovative Genomics Institute, Berkeley, California 94720, USA
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34
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Mills BB, Thomas AD, Riddle NC. HP1B is a euchromatic Drosophila HP1 homolog with links to metabolism. PLoS One 2018; 13:e0205867. [PMID: 30346969 PMCID: PMC6197686 DOI: 10.1371/journal.pone.0205867] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Accepted: 10/02/2018] [Indexed: 11/30/2022] Open
Abstract
Heterochromatin Protein 1 (HP1) proteins are an important family of chromosomal proteins conserved among all major eukaryotic lineages. While HP1 proteins are best known for their role in heterochromatin, many HP1 proteins function in euchromatin as well. As a group, HP1 proteins carry out diverse functions, playing roles in the regulation of gene expression, genome stability, chromatin structure, and DNA repair. While the heterochromatic HP1 proteins are well studied, our knowledge of HP1 proteins with euchromatic distribution is lagging behind. We have created the first mutations in HP1B, a Drosophila HP1 protein with euchromatic function, and the Drosophila homolog most closely related to mammalian HP1α, HP1β, and HP1γ. We find that HP1B is a non-essential protein in Drosophila, with mutations affecting fertility and animal activity levels. In addition, animals lacking HP1B show altered food intake and higher body fat levels. Gene expression analysis of animals lacking HP1B demonstrates that genes with functions in various metabolic processes are affected primarily by HP1B loss. Our findings suggest that there is a link between the chromatin protein HP1B and the regulation of metabolism.
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Affiliation(s)
- Benjamin B. Mills
- Department of Biology, The University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Andrew D. Thomas
- Department of Biology, The University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Nicole C. Riddle
- Department of Biology, The University of Alabama at Birmingham, Birmingham, Alabama, United States of America
- * E-mail:
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35
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Yang YF, Pan YH, Tian QH, Wu DC, Su SG. CBX1 Indicates Poor Outcomes and Exerts Oncogenic Activity in Hepatocellular Carcinoma. Transl Oncol 2018; 11:1110-1118. [PMID: 30031230 PMCID: PMC6074001 DOI: 10.1016/j.tranon.2018.07.002] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2018] [Revised: 06/26/2018] [Accepted: 07/02/2018] [Indexed: 12/13/2022] Open
Abstract
Dysregulation of chromobox proteins contributes to the progression of human diseases. CBX1 has been implicated in epigenetic control of chromatin structure and gene expression, but its role in human cancers remains largely unknown. Here we show that CBX1 exhibits oncogenic activities in hepatocellular carcinoma (HCC) and indicates poor outcomes. The expression of CBX1 was noticeably increased, at both mRNA and protein levels, in HCC tissues and cell lines, compared with the nontumorous ones. High CBX1 expression was significantly associated with larger tumor size, poor tumor differentiation and tumor vascular invasion. Patients with elevated expression of CBX1 were frequently accompanied with unfavorable overall and disease-free survivals in two independent cohorts consisting of 648 HCC cases. The prognostic value of CBX1 was further confirmed by stratified survival analyses. Multivariate cox regression model suggested CBX1 as an independent factor for overall survival (hazard ratio = 1.735, 95% confident interval: 1.342–2.244, P < .001). In vitro data demonstrated that CBX1 overexpression promoted cell proliferation and migration, whereas the knockdown of CBX1 resulted in the opposite phenotypes. Mechanistically, CBX1 interacted with transcription factor HMGA2 to activate the Wnt/β-Catenin signaling pathway. Suppression of β-Catenin by siRNA or specific inhibitor XAV-939 markedly attenuated CBX1-mediated cell growth. Collectively, our findings indicate that CBX1 functions as an oncogene and may serve as a potential prognostic biomarker in HCC.
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Affiliation(s)
- Yu-Feng Yang
- Department of Pathology, Dongguan Third People's Hospital, Dongguan, China
| | - Ying-Hua Pan
- Department of Rheumatology, The Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
| | - Qiu-Hong Tian
- Department of Oncology, First Affiliated Hospital of NanChang University, NanChang, Jiangxi 330006, China
| | - Dan-Chun Wu
- Department of Rheumatology, The Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
| | - Shu-Guang Su
- Department of Pathology, The Affiliated Hexian Memorial Hospital of Southern Medical University, Guangzhou, China.
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36
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Papachristou EK, Kishore K, Holding AN, Harvey K, Roumeliotis TI, Chilamakuri CSR, Omarjee S, Chia KM, Swarbrick A, Lim E, Markowetz F, Eldridge M, Siersbaek R, D'Santos CS, Carroll JS. A quantitative mass spectrometry-based approach to monitor the dynamics of endogenous chromatin-associated protein complexes. Nat Commun 2018; 9:2311. [PMID: 29899353 PMCID: PMC5998130 DOI: 10.1038/s41467-018-04619-5] [Citation(s) in RCA: 83] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Accepted: 05/03/2018] [Indexed: 11/10/2022] Open
Abstract
Understanding the dynamics of endogenous protein-protein interactions in complex networks is pivotal in deciphering disease mechanisms. To enable the in-depth analysis of protein interactions in chromatin-associated protein complexes, we have previously developed a method termed RIME (Rapid Immunoprecipitation Mass spectrometry of Endogenous proteins). Here, we present a quantitative multiplexed method (qPLEX-RIME), which integrates RIME with isobaric labelling and tribrid mass spectrometry for the study of protein interactome dynamics in a quantitative fashion with increased sensitivity. Using the qPLEX-RIME method, we delineate the temporal changes of the Estrogen Receptor alpha (ERα) interactome in breast cancer cells treated with 4-hydroxytamoxifen. Furthermore, we identify endogenous ERα-associated proteins in human Patient-Derived Xenograft tumours and in primary human breast cancer clinical tissue. Our results demonstrate that the combination of RIME with isobaric labelling offers a powerful tool for the in-depth and quantitative characterisation of protein interactome dynamics, which is applicable to clinical samples.
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Affiliation(s)
- Evangelia K Papachristou
- Cancer Research UK Cambridge Institute, University of Cambridge, Robinson Way, Cambridge, CB2 0RE, UK
| | - Kamal Kishore
- Cancer Research UK Cambridge Institute, University of Cambridge, Robinson Way, Cambridge, CB2 0RE, UK
| | - Andrew N Holding
- Cancer Research UK Cambridge Institute, University of Cambridge, Robinson Way, Cambridge, CB2 0RE, UK
| | - Kate Harvey
- Garvan Institute of Medical Research, Darlinghurst, Sydney, NSW 2010, Australia
| | | | | | - Soleilmane Omarjee
- Cancer Research UK Cambridge Institute, University of Cambridge, Robinson Way, Cambridge, CB2 0RE, UK
| | - Kee Ming Chia
- Garvan Institute of Medical Research, Darlinghurst, Sydney, NSW 2010, Australia
| | - Alex Swarbrick
- Garvan Institute of Medical Research, Darlinghurst, Sydney, NSW 2010, Australia
- St Vincent's Clinical School, UNSW, Sydney, NSW 2052, Australia
| | - Elgene Lim
- Garvan Institute of Medical Research, Darlinghurst, Sydney, NSW 2010, Australia
- St Vincent's Clinical School, UNSW, Sydney, NSW 2052, Australia
| | - Florian Markowetz
- Cancer Research UK Cambridge Institute, University of Cambridge, Robinson Way, Cambridge, CB2 0RE, UK
| | - Matthew Eldridge
- Cancer Research UK Cambridge Institute, University of Cambridge, Robinson Way, Cambridge, CB2 0RE, UK
| | - Rasmus Siersbaek
- Cancer Research UK Cambridge Institute, University of Cambridge, Robinson Way, Cambridge, CB2 0RE, UK.
| | - Clive S D'Santos
- Cancer Research UK Cambridge Institute, University of Cambridge, Robinson Way, Cambridge, CB2 0RE, UK. Clive.D'
| | - Jason S Carroll
- Cancer Research UK Cambridge Institute, University of Cambridge, Robinson Way, Cambridge, CB2 0RE, UK.
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Watanabe S, Mishima Y, Shimizu M, Suetake I, Takada S. Interactions of HP1 Bound to H3K9me3 Dinucleosome by Molecular Simulations and Biochemical Assays. Biophys J 2018; 114:2336-2351. [PMID: 29685391 PMCID: PMC6129468 DOI: 10.1016/j.bpj.2018.03.025] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Revised: 02/27/2018] [Accepted: 03/26/2018] [Indexed: 01/01/2023] Open
Abstract
Heterochromatin protein 1 (HP1), associated with heterochromatin formation, recognizes an epigenetically repressive marker, trimethylated lysine 9 in histone H3 (H3K9me3), and generally contributes to long-term silencing. How HP1 induces heterochromatin is not fully understood. Recent experiments suggested that not one, but two nucleosomes provide a platform for this recognition. Integrating previous and new biochemical assays with computational modeling, we provide near-atomic structural models for HP1 binding to the dinucleosomes. We found that the dimeric HP1α tends to bind two H3K9me3s that are in adjacent nucleosomes, thus bridging two nucleosomes. We identified, to our knowledge, a novel DNA binding motif in the hinge region that is specific to HP1α and is essential for recognizing the H3K9me3 sites of two nucleosomes. An HP1 isoform, HP1γ, does not easily bridge two nucleosomes in extended conformations because of the absence of the above binding motif and its shorter hinge region. We propose a molecular mechanism for chromatin structural changes caused by HP1.
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Affiliation(s)
- Shuhei Watanabe
- Department of Biophysics, Graduate School of Science, Kyoto University, Kitashirakawa, Sakyo, Kyoto, Japan
| | - Yuichi Mishima
- Institute for Protein Research, Osaka University, Suita, Osaka, Japan
| | - Masahiro Shimizu
- Department of Biophysics, Graduate School of Science, Kyoto University, Kitashirakawa, Sakyo, Kyoto, Japan
| | - Isao Suetake
- Institute for Protein Research, Osaka University, Suita, Osaka, Japan; College of Nutrition, Koshien University, Takarazuka, Japan.
| | - Shoji Takada
- Department of Biophysics, Graduate School of Science, Kyoto University, Kitashirakawa, Sakyo, Kyoto, Japan.
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38
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Knight SC, Tjian R, Doudna JA. Genomes in Focus: Development and Applications of CRISPR-Cas9 Imaging Technologies. Angew Chem Int Ed Engl 2018; 57:4329-4337. [PMID: 29080263 PMCID: PMC6014596 DOI: 10.1002/anie.201709201] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Indexed: 12/14/2022]
Abstract
The discovery of the CRISPR-Cas9 endonuclease has enabled facile genome editing in living cells and organisms. Catalytically inactive Cas9 (dCas9) retains the ability to bind DNA in an RNA-guided fashion, and has additionally been explored as a tool for transcriptional modulation, epigenetic editing, and genome imaging. This Review highlights recent progress and challenges in the development of dCas9 for imaging genomic loci. The emergence and maturation of this technology offers the potential to answer mechanistic questions about chromosome dynamics and three-dimensional genome organization in vivo.
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Affiliation(s)
- Spencer C Knight
- Department of Chemistry, University of California, Berkeley, Berkeley, CA, USA
| | - Robert Tjian
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, USA
- Howard Hughes Medical Institute, USA
- Li Ka Shing Biomedical and Health Sciences Center, University of California, Berkeley, Berkeley, CA, USA
- CIRM Center of Excellence, University of California, Berkeley, Berkeley, CA, USA
| | - Jennifer A Doudna
- Department of Chemistry, University of California, Berkeley, Berkeley, CA, USA
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, USA
- Howard Hughes Medical Institute, USA
- Li Ka Shing Biomedical and Health Sciences Center, University of California, Berkeley, Berkeley, CA, USA
- MBIB Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- Innovative Genomics Institute, University of California, Berkeley, Berkeley, CA, USA
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A comprehensive map coupling histone modifications with gene regulation in adult dopaminergic and serotonergic neurons. Nat Commun 2018; 9:1226. [PMID: 29581424 PMCID: PMC5964330 DOI: 10.1038/s41467-018-03538-9] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2017] [Accepted: 02/21/2018] [Indexed: 12/22/2022] Open
Abstract
The brain is composed of hundreds of different neuronal subtypes, which largely retain their identity throughout the lifespan of the organism. The mechanisms governing this stability are not fully understood, partly due to the diversity and limited size of clinically relevant neuronal populations, which constitute a technical challenge for analysis. Here, using a strategy that allows for ChIP-seq combined with RNA-seq in small neuronal populations in vivo, we present a comparative analysis of permissive and repressive histone modifications in adult midbrain dopaminergic neurons, raphe nuclei serotonergic neurons, and embryonic neural progenitors. Furthermore, we utilize the map generated by our analysis to show that the transcriptional response of midbrain dopaminergic neurons following 6-OHDA or methamphetamine injection is characterized by increased expression of genes with promoters dually marked by H3K4me3/H3K27me3. Our study provides an in vivo genome-wide analysis of permissive/repressive histone modifications coupled to gene expression in these rare neuronal subtypes. The limited size of some neuronal types and their entangled environment renders it difficult to study their transcription regulation. Here the authors present a comparative analysis of histone modifications and transcription in dopaminergic and serotonergic neurons and embryonic neural progenitors.
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40
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Knight SC, Tjian R, Doudna JA. Genome im Fokus: Entwicklung und Anwendungen von CRISPR-Cas9-Bildgebungstechnologien. Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201709201] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
| | - Robert Tjian
- Department of Molecular and Cell Biology; University of California; Berkeley CA USA
- Howard Hughes Medical Institute; USA
- Li Ka Shing Biomedical and Health Sciences Center; University of California; Berkeley CA USA
- CIRM Center of Excellence; University of California, Berkeley; Berkeley CA USA
| | - Jennifer A. Doudna
- Department of Chemistry; University of California; Berkeley CA USA
- Department of Molecular and Cell Biology; University of California; Berkeley CA USA
- Howard Hughes Medical Institute; USA
- Li Ka Shing Biomedical and Health Sciences Center; University of California; Berkeley CA USA
- MBIB Division; Lawrence Berkeley National Laboratory; Berkeley CA USA. Innovative Genomics Institute; University of California, Berkeley; Berkeley CA USA
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Popova VV, Brechalov AV, Georgieva SG, Kopytova DV. Nonreplicative functions of the origin recognition complex. Nucleus 2018; 9:460-473. [PMID: 30196754 PMCID: PMC6244734 DOI: 10.1080/19491034.2018.1516484] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Revised: 08/04/2018] [Accepted: 08/16/2018] [Indexed: 12/14/2022] Open
Abstract
Origin recognition complex (ORC), a heteromeric six-subunit complex, is the central component of the eukaryotic pre-replication complex. Recent data from yeast, frogs, flies and mammals present compelling evidence that ORC and its individual subunits have nonreplicative functions as well. The majority of these functions, such as heterochromatin formation, chromosome condensation, and segregation are dependent on ORC-DNA interactions. Furthermore, ORC is involved in the control of cell division via its participation in centrosome duplication and cytokinesis. Recent findings have also demonstrated a direct interaction between ORC and mRNPs and highlighted an essential role of ORC in mRNA nuclear export. Along with the growth of evolutionary complexity of organisms, ORC complex functions become more elaborate and new functions of the ORC sub-complexes and individual subunits have emerged.
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Affiliation(s)
- Varvara V. Popova
- Department of Transcription Regulation and Chromatin Dynamics, Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia
| | - Alexander V. Brechalov
- Department of Transcription Regulation and Chromatin Dynamics, Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia
| | - Sofia G. Georgieva
- Department of Transcription Regulation and Chromatin Dynamics, Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia
| | - Daria V. Kopytova
- Department of Transcription Regulation and Chromatin Dynamics, Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia
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42
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Drosophila Histone Demethylase KDM4A Has Enzymatic and Non-enzymatic Roles in Controlling Heterochromatin Integrity. Dev Cell 2017; 42:156-169.e5. [PMID: 28743002 DOI: 10.1016/j.devcel.2017.06.014] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Revised: 03/21/2017] [Accepted: 06/16/2017] [Indexed: 11/23/2022]
Abstract
Eukaryotic genomes are broadly divided between gene-rich euchromatin and the highly repetitive heterochromatin domain, which is enriched for proteins critical for genome stability and transcriptional silencing. This study shows that Drosophila KDM4A (dKDM4A), previously characterized as a euchromatic histone H3 K36 demethylase and transcriptional regulator, predominantly localizes to heterochromatin and regulates heterochromatin position-effect variegation (PEV), organization of repetitive DNAs, and DNA repair. We demonstrate that dKDM4A demethylase activity is dispensable for PEV. In contrast, dKDM4A enzymatic activity is required to relocate heterochromatic double-strand breaks outside the domain, as well as for organismal survival when DNA repair is compromised. Finally, DNA damage triggers dKDM4A-dependent changes in the levels of H3K56me3, suggesting that dKDM4A demethylates this heterochromatic mark to facilitate repair. We conclude that dKDM4A, in addition to its previously characterized role in euchromatin, utilizes both enzymatic and structural mechanisms to regulate heterochromatin organization and functions.
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43
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Kaczmarczyk A, Allahverdi A, Brouwer TB, Nordenskiöld L, Dekker NH, van Noort J. Single-molecule force spectroscopy on histone H4 tail-cross-linked chromatin reveals fiber folding. J Biol Chem 2017; 292:17506-17513. [PMID: 28855255 DOI: 10.1074/jbc.m117.791830] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Revised: 08/21/2017] [Indexed: 01/06/2023] Open
Abstract
The eukaryotic genome is highly compacted into a protein-DNA complex called chromatin. The cell controls access of transcriptional regulators to chromosomal DNA via several mechanisms that act on chromatin-associated proteins and provide a rich spectrum of epigenetic regulation. Elucidating the mechanisms that fold chromatin fibers into higher-order structures is therefore key to understanding the epigenetic regulation of DNA accessibility. Here, using histone H4-V21C and histone H2A-E64C mutations, we employed single-molecule force spectroscopy to measure the unfolding of individual chromatin fibers that are reversibly cross-linked through the histone H4 tail. Fibers with covalently linked nucleosomes featured the same folding characteristics as fibers containing wild-type histones but exhibited increased stability against stretching forces. By stabilizing the secondary structure of chromatin, we confirmed a nucleosome repeat length (NRL)-dependent folding. Consistent with previous crystallographic and cryo-EM studies, the obtained force-extension curves on arrays with 167-bp NRLs best supported an underlying structure consisting of zig-zag, two-start fibers. For arrays with 197-bp NRLs, we previously inferred solenoidal folding, which was further corroborated by force-extension curves of the cross-linked fibers. The different unfolding pathways exhibited by these two types of arrays and reported here extend our understanding of chromatin structure and its potential roles in gene regulation. Importantly, these findings imply that chromatin compaction by nucleosome stacking protects nucleosomal DNA from external forces up to 4 piconewtons.
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Affiliation(s)
- Artur Kaczmarczyk
- From the Huygens-Kamerlingh Onnes Laboratory, Leiden University, Niels Bohrweg 2, 2333 CA Leiden, The Netherlands.,Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands, and
| | - Abdollah Allahverdi
- School of Biological Sciences, Nanyang Technological University, Singapore 639798, Singapore
| | - Thomas B Brouwer
- From the Huygens-Kamerlingh Onnes Laboratory, Leiden University, Niels Bohrweg 2, 2333 CA Leiden, The Netherlands
| | - Lars Nordenskiöld
- School of Biological Sciences, Nanyang Technological University, Singapore 639798, Singapore
| | - Nynke H Dekker
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands, and
| | - John van Noort
- From the Huygens-Kamerlingh Onnes Laboratory, Leiden University, Niels Bohrweg 2, 2333 CA Leiden, The Netherlands,
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44
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Larson AG, Elnatan D, Keenen MM, Trnka MJ, Johnston JB, Burlingame AL, Agard DA, Redding S, Narlikar GJ. Liquid droplet formation by HP1α suggests a role for phase separation in heterochromatin. Nature 2017; 547:236-240. [PMID: 28636604 PMCID: PMC5606208 DOI: 10.1038/nature22822] [Citation(s) in RCA: 1096] [Impact Index Per Article: 156.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Accepted: 05/16/2017] [Indexed: 01/15/2023]
Abstract
Gene silencing by heterochromatin is proposed to occur in part as a result of the ability of heterochromatin protein 1 (HP1) proteins to spread across large regions of the genome, compact the underlying chromatin and recruit diverse ligands. Here we identify a new property of the human HP1α protein: the ability to form phase-separated droplets. While unmodified HP1α is soluble, either phosphorylation of its N-terminal extension or DNA binding promotes the formation of phase-separated droplets. Phosphorylation-driven phase separation can be promoted or reversed by specific HP1α ligands. Known components of heterochromatin such as nucleosomes and DNA preferentially partition into the HP1α droplets, but molecules such as the transcription factor TFIIB show no preference. Using a single-molecule DNA curtain assay, we find that both unmodified and phosphorylated HP1α induce rapid compaction of DNA strands into puncta, although with different characteristics. We show by direct protein delivery into mammalian cells that an HP1α mutant incapable of phase separation in vitro forms smaller and fewer nuclear puncta than phosphorylated HP1α. These findings suggest that heterochromatin-mediated gene silencing may occur in part through sequestration of compacted chromatin in phase-separated HP1 droplets, which are dissolved or formed by specific ligands on the basis of nuclear context.
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Affiliation(s)
- Adam G. Larson
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94158, USA
- Tetrad Graduate Program, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Daniel Elnatan
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94158, USA
- Tetrad Graduate Program, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Madeline M. Keenen
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94158, USA
- Tetrad Graduate Program, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Michael J. Trnka
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Jonathan B. Johnston
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Alma L. Burlingame
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, CA 94158, USA
| | - David A. Agard
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94158, USA
- Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Sy Redding
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Geeta J. Narlikar
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94158, USA
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45
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Janssen A, Breuer GA, Brinkman EK, van der Meulen AI, Borden SV, van Steensel B, Bindra RS, LaRocque JR, Karpen GH. A single double-strand break system reveals repair dynamics and mechanisms in heterochromatin and euchromatin. Genes Dev 2017; 30:1645-57. [PMID: 27474442 PMCID: PMC4973294 DOI: 10.1101/gad.283028.116] [Citation(s) in RCA: 77] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Accepted: 07/05/2016] [Indexed: 01/04/2023]
Abstract
Janssen et al. developed an in vivo single double-strand break (DSB) system for both heterochromatic and euchromatic loci in Drosophila melanogaster. Live imaging and sequence analysis of repair products reveal that DSBs in euchromatin and heterochromatin are repaired with similar kinetics, employ both NHEJ and HR, and can use homologous chromosomes as an HR template. Repair of DNA double-strand breaks (DSBs) must be properly orchestrated in diverse chromatin regions to maintain genome stability. The choice between two main DSB repair pathways, nonhomologous end-joining (NHEJ) and homologous recombination (HR), is regulated by the cell cycle as well as chromatin context. Pericentromeric heterochromatin forms a distinct nuclear domain that is enriched for repetitive DNA sequences that pose significant challenges for genome stability. Heterochromatic DSBs display specialized temporal and spatial dynamics that differ from euchromatic DSBs. Although HR is thought to be the main pathway used to repair heterochromatic DSBs, direct tests of this hypothesis are lacking. Here, we developed an in vivo single DSB system for both heterochromatic and euchromatic loci in Drosophila melanogaster. Live imaging of single DSBs in larval imaginal discs recapitulates the spatio–temporal dynamics observed for irradiation (IR)-induced breaks in cell culture. Importantly, live imaging and sequence analysis of repair products reveal that DSBs in euchromatin and heterochromatin are repaired with similar kinetics, employ both NHEJ and HR, and can use homologous chromosomes as an HR template. This direct analysis reveals important insights into heterochromatin DSB repair in animal tissues and provides a foundation for further explorations of repair mechanisms in different chromatin domains.
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Affiliation(s)
- Aniek Janssen
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Gregory A Breuer
- Department of Therapeutic Radiology, Yale School of Medicine, New Haven, Connecticut 06510, USA; Department of Experimental Pathology, Yale School of Medicine, New Haven, Connecticut 06510, USA
| | - Eva K Brinkman
- Division of Gene Regulation, Netherlands Cancer Institute, Amsterdam 1066 CX, the Netherlands
| | - Annelot I van der Meulen
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Sean V Borden
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Bas van Steensel
- Division of Gene Regulation, Netherlands Cancer Institute, Amsterdam 1066 CX, the Netherlands
| | - Ranjit S Bindra
- Department of Therapeutic Radiology, Yale School of Medicine, New Haven, Connecticut 06510, USA; Department of Experimental Pathology, Yale School of Medicine, New Haven, Connecticut 06510, USA
| | - Jeannine R LaRocque
- Department of Human Science, School of Nursing and Health Studies, Georgetown University Medical Center, Washington, DC 20057, USA
| | - Gary H Karpen
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA; Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, California 94720, USA
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46
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Abstract
The eukaryotic nucleus is enclosed by the nuclear envelope, which is perforated by the nuclear pores, the gateways of macromolecular exchange between the nucleoplasm and cytoplasm. The nucleoplasm is organized in a complex three-dimensional fashion that changes over time and in response to stimuli. Within the cell, the nucleus must be viewed as an organelle (albeit a gigantic one) that is a recipient of cytoplasmic forces and capable of morphological and positional dynamics. The most dramatic reorganization of this organelle occurs during mitosis and meiosis. Although many of these aspects are less well understood for the nuclei of plants than for those of animals or fungi, several recent discoveries have begun to place our understanding of plant nuclei firmly into this broader cell-biological context.
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Affiliation(s)
- Iris Meier
- Department of Molecular Genetics, The Ohio State University, Columbus, Ohio 43210;
- Department of Biological and Medical Sciences, Oxford Brookes University, Oxford OX3 0BP, United Kingdom;
| | | | - David E Evans
- Department of Biological and Medical Sciences, Oxford Brookes University, Oxford OX3 0BP, United Kingdom;
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47
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Liu Y, Qin S, Lei M, Tempel W, Zhang Y, Loppnau P, Li Y, Min J. Peptide recognition by heterochromatin protein 1 (HP1) chromoshadow domains revisited: Plasticity in the pseudosymmetric histone binding site of human HP1. J Biol Chem 2017; 292:5655-5664. [PMID: 28223359 DOI: 10.1074/jbc.m116.768374] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Revised: 02/16/2017] [Indexed: 12/26/2022] Open
Abstract
Heterochromatin protein 1 (HP1), a highly conserved non-histone chromosomal protein in eukaryotes, plays important roles in the regulation of gene transcription. Each of the three human homologs of HP1 includes a chromoshadow domain (CSD). The CSD interacts with various proteins bearing the PXVXL motif but also with a region of histone H3 that bears the similar PXXVXL motif. The latter interaction has not yet been resolved in atomic detail. Here we demonstrate that the CSDs of all three human HP1 homologs have comparable affinities to the PXXVXL motif of histone H3. The HP1 C-terminal extension enhances the affinity, as does the increasing length of the H3 peptide. The crystal structure of the human HP1γ CSD (CSDγ) in complex with an H3 peptide suggests that recognition of H3 by CSDγ to some extent resembles CSD-PXVXL interaction. Nevertheless, the prolyl residue of the PXXVXL motif appears to play a role distinct from that of Pro in the known HP1β CSD-PXVXL complexes. We consequently generalize the historical CSD-PXVXL interaction model and expand the search scope for additional CSD binding partners.
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Affiliation(s)
- Yanli Liu
- From the Structural Genomics Consortium, University of Toronto, Toronto, Ontario M5G 1L7, Canada and
| | - Su Qin
- From the Structural Genomics Consortium, University of Toronto, Toronto, Ontario M5G 1L7, Canada and
| | - Ming Lei
- From the Structural Genomics Consortium, University of Toronto, Toronto, Ontario M5G 1L7, Canada and
| | - Wolfram Tempel
- From the Structural Genomics Consortium, University of Toronto, Toronto, Ontario M5G 1L7, Canada and
| | - Yuzhe Zhang
- From the Structural Genomics Consortium, University of Toronto, Toronto, Ontario M5G 1L7, Canada and
| | - Peter Loppnau
- From the Structural Genomics Consortium, University of Toronto, Toronto, Ontario M5G 1L7, Canada and
| | - Yanjun Li
- From the Structural Genomics Consortium, University of Toronto, Toronto, Ontario M5G 1L7, Canada and
| | - Jinrong Min
- From the Structural Genomics Consortium, University of Toronto, Toronto, Ontario M5G 1L7, Canada and .,the Department of Physiology, University of Toronto, Toronto, Ontario M5S 1A8, Canada
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48
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Caizzi R, Moschetti R, Piacentini L, Fanti L, Marsano RM, Dimitri P. Comparative Genomic Analyses Provide New Insights into the Evolutionary Dynamics of Heterochromatin in Drosophila. PLoS Genet 2016; 12:e1006212. [PMID: 27513559 PMCID: PMC4981424 DOI: 10.1371/journal.pgen.1006212] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2015] [Accepted: 07/02/2016] [Indexed: 12/21/2022] Open
Abstract
The term heterochromatin has been long considered synonymous with gene silencing, but it is now clear that the presence of transcribed genes embedded in pericentromeric heterochromatin is a conserved feature in the evolution of eukaryotic genomes. Several studies have addressed the epigenetic changes that enable the expression of genes in pericentric heterochromatin, yet little is known about the evolutionary processes through which this has occurred. By combining genome annotation analysis and high-resolution cytology, we have identified and mapped 53 orthologs of D. melanogaster heterochromatic genes in the genomes of two evolutionarily distant species, D. pseudoobscura and D. virilis. Our results show that the orthologs of the D. melanogaster heterochromatic genes are clustered at three main genomic regions in D. virilis and D. pseudoobscura. In D. virilis, the clusters lie in the middle of euchromatin, while those in D. pseudoobscura are located in the proximal portion of the chromosome arms. Some orthologs map to the corresponding Muller C element in D. pseudoobscura and D. virilis, while others localize on the Muller B element, suggesting that chromosomal rearrangements that have been instrumental in the fusion of two separate elements involved the progenitors of genes currently located in D. melanogaster heterochromatin. These results demonstrate an evolutionary repositioning of gene clusters from ancestral locations in euchromatin to the pericentromeric heterochromatin of descendent D. melanogaster chromosomes. Remarkably, in both D. virilis and D. pseudoobscura the gene clusters show a conserved association with the HP1a protein, one of the most highly evolutionarily conserved epigenetic marks. In light of these results, we suggest a new scenario whereby ancestral HP1-like proteins (and possibly other epigenetic marks) may have contributed to the evolutionary repositioning of gene clusters into heterochromatin.
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Affiliation(s)
- Ruggiero Caizzi
- Dipartimento di Biologia, Università degli Studi di Bari, Bari, Italy
- * E-mail: (RC); (PD)
| | - Roberta Moschetti
- Dipartimento di Biologia, Università degli Studi di Bari, Bari, Italy
| | - Lucia Piacentini
- Istituto Pasteur Italia-Fondazione Cenci Bolognetti, Dipartimento di Biologia e Biotecnologie ‘‘Charles Darwin”, Sapienza Università di Roma, Roma, Italy
| | - Laura Fanti
- Istituto Pasteur Italia-Fondazione Cenci Bolognetti, Dipartimento di Biologia e Biotecnologie ‘‘Charles Darwin”, Sapienza Università di Roma, Roma, Italy
| | | | - Patrizio Dimitri
- Istituto Pasteur Italia-Fondazione Cenci Bolognetti, Dipartimento di Biologia e Biotecnologie ‘‘Charles Darwin”, Sapienza Università di Roma, Roma, Italy
- * E-mail: (RC); (PD)
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49
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Knight SC, Xie L, Deng W, Guglielmi B, Witkowsky LB, Bosanac L, Zhang ET, El Beheiry M, Masson JB, Dahan M, Liu Z, Doudna JA, Tjian R. Dynamics of CRISPR-Cas9 genome interrogation in living cells. Science 2015; 350:823-6. [PMID: 26564855 DOI: 10.1126/science.aac6572] [Citation(s) in RCA: 232] [Impact Index Per Article: 25.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The RNA-guided CRISPR-associated protein Cas9 is used for genome editing, transcriptional modulation, and live-cell imaging. Cas9-guide RNA complexes recognize and cleave double-stranded DNA sequences on the basis of 20-nucleotide RNA-DNA complementarity, but the mechanism of target searching in mammalian cells is unknown. Here, we use single-particle tracking to visualize diffusion and chromatin binding of Cas9 in living cells. We show that three-dimensional diffusion dominates Cas9 searching in vivo, and off-target binding events are, on average, short-lived (<1 second). Searching is dependent on the local chromatin environment, with less sampling and slower movement within heterochromatin. These results reveal how the bacterial Cas9 protein interrogates mammalian genomes and navigates eukaryotic chromatin structure.
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Affiliation(s)
- Spencer C Knight
- Department of Chemistry, University of California, Berkeley, CA, USA
| | - Liangqi Xie
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA
| | - Wulan Deng
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA. Transcriptional Imaging Consortium, Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Benjamin Guglielmi
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA
| | - Lea B Witkowsky
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA
| | - Lana Bosanac
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA
| | - Elisa T Zhang
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA
| | - Mohamed El Beheiry
- Laboratoire Physico-Chimie Curie, Institut Curie, Centre National de la Recherche Scientifique UMR 168, Paris, France
| | | | - Maxime Dahan
- Transcriptional Imaging Consortium, Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA. Laboratoire Physico-Chimie Curie, Institut Curie, Centre National de la Recherche Scientifique UMR 168, Paris, France
| | - Zhe Liu
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA. Transcriptional Imaging Consortium, Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA.
| | - Jennifer A Doudna
- Department of Chemistry, University of California, Berkeley, CA, USA. Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA. Howard Hughes Medical Institute, Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA. Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA. Innovative Genomics Initiative, University of California, Berkeley, CA, USA.
| | - Robert Tjian
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA. Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA. Transcriptional Imaging Consortium, Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA. Howard Hughes Medical Institute, Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA. Li Ka Shing Biomedical and Health Sciences Center, University of California, Berkeley, CA, USA.
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Conserved factor Dhp1/Rat1/Xrn2 triggers premature transcription termination and nucleates heterochromatin to promote gene silencing. Proc Natl Acad Sci U S A 2015; 112:15548-55. [PMID: 26631744 DOI: 10.1073/pnas.1522127112] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Cotranscriptional RNA processing and surveillance factors mediate heterochromatin formation in diverse eukaryotes. In fission yeast, RNAi machinery and RNA elimination factors including the Mtl1-Red1 core and the exosome are involved in facultative heterochromatin assembly; however, the exact mechanisms remain unclear. Here we show that RNA elimination factors cooperate with the conserved exoribonuclease Dhp1/Rat1/Xrn2, which couples pre-mRNA 3'-end processing to transcription termination, to promote premature termination and facultative heterochromatin formation at meiotic genes. We also find that Dhp1 is critical for RNAi-mediated heterochromatin assembly at retroelements and regulated gene loci and facilitates the formation of constitutive heterochromatin at centromeric and mating-type loci. Remarkably, our results reveal that Dhp1 interacts with the Clr4/Suv39h methyltransferase complex and acts directly to nucleate heterochromatin. Our work uncovers a previously unidentified role for 3'-end processing and transcription termination machinery in gene silencing through premature termination and suggests that noncanonical transcription termination by Dhp1 and RNA elimination factors is linked to heterochromatin assembly. These findings have important implications for understanding silencing mechanisms targeting genes and repeat elements in higher eukaryotes.
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