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Chavan A, Isenhart R, Nguyen SC, Kotb NM, Harke J, Sintsova A, Ulukaya G, Uliana F, Ashiono C, Kutay U, Pegoraro G, Rangan P, Joyce EF, Jagannathan M. A nuclear architecture screen in Drosophila identifies Stonewall as a link between chromatin position at the nuclear periphery and germline stem cell fate. Genes Dev 2024; 38:415-435. [PMID: 38866555 PMCID: PMC11216176 DOI: 10.1101/gad.351424.123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2023] [Accepted: 05/21/2024] [Indexed: 06/14/2024]
Abstract
The association of genomic loci to the nuclear periphery is proposed to facilitate cell type-specific gene repression and influence cell fate decisions. However, the interplay between gene position and expression remains incompletely understood, in part because the proteins that position genomic loci at the nuclear periphery remain unidentified. Here, we used an Oligopaint-based HiDRO screen targeting ∼1000 genes to discover novel regulators of nuclear architecture in Drosophila cells. We identified the heterochromatin-associated protein Stonewall (Stwl) as a factor promoting perinuclear chromatin positioning. In female germline stem cells (GSCs), Stwl binds and positions chromatin loci, including GSC differentiation genes, at the nuclear periphery. Strikingly, Stwl-dependent perinuclear positioning is associated with transcriptional repression, highlighting a likely mechanism for Stwl's known role in GSC maintenance and ovary homeostasis. Thus, our study identifies perinuclear anchors in Drosophila and demonstrates the importance of gene repression at the nuclear periphery for cell fate.
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Affiliation(s)
- Ankita Chavan
- Institute of Biochemistry, Department of Biology, Eidgenössische Technische Hochschule (ETH) Zürich, Zürich 8093, Switzerland
- Bringing Materials to Life Consortium, ETH Zürich, Zürich 8093, Switzerland
- Life Science Zürich Graduate School, Zürich 8057, Switzerland
| | - Randi Isenhart
- Penn Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Son C Nguyen
- Penn Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Noor M Kotb
- Department of Cell, Developmental, and Regenerative Biology, Black Family Stem Cell Institute, Icahn School of Medicine at Mount Sinai, New York, New York 10029, USA
| | - Jailynn Harke
- Penn Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Anna Sintsova
- Institute of Microbiology, Department of Biology, ETH Zürich, Zürich 8093, Switzerland
| | - Gulay Ulukaya
- Bioinformatics for Next-Generation Sequencing (BiNGS) Core, Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, New York 10029, USA
| | - Federico Uliana
- Institute of Biochemistry, Department of Biology, Eidgenössische Technische Hochschule (ETH) Zürich, Zürich 8093, Switzerland
| | - Caroline Ashiono
- Institute of Biochemistry, Department of Biology, Eidgenössische Technische Hochschule (ETH) Zürich, Zürich 8093, Switzerland
| | - Ulrike Kutay
- Institute of Biochemistry, Department of Biology, Eidgenössische Technische Hochschule (ETH) Zürich, Zürich 8093, Switzerland
| | - Gianluca Pegoraro
- High-Throughput Imaging Facility (HiTIF), National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Prashanth Rangan
- Department of Cell, Developmental, and Regenerative Biology, Black Family Stem Cell Institute, Icahn School of Medicine at Mount Sinai, New York, New York 10029, USA
| | - Eric F Joyce
- Penn Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA;
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Madhav Jagannathan
- Institute of Biochemistry, Department of Biology, Eidgenössische Technische Hochschule (ETH) Zürich, Zürich 8093, Switzerland;
- Bringing Materials to Life Consortium, ETH Zürich, Zürich 8093, Switzerland
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Liu Z, Wang W, Xia Y, Gao Y, Wang Z, Li M, Presicce GA, An L, Du F. Overcoming the H4K20me3 epigenetic barrier improves somatic cell nuclear transfer reprogramming efficiency in mice. Cell Prolif 2024; 57:e13519. [PMID: 37322828 PMCID: PMC10771106 DOI: 10.1111/cpr.13519] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 05/25/2023] [Accepted: 06/05/2023] [Indexed: 06/17/2023] Open
Abstract
Epigenetic reprogramming during fertilization and somatic cell nuclear transfer (NT) is required for cell plasticity and competent development. Here, we characterize the epigenetic modification pattern of H4K20me3, a repressive histone signature in heterochromatin, during fertilization and NT reprogramming. Importantly, the dynamic H4K20me3 signature identified during preimplantation development in fertilized embryos differed from NT and parthenogenetic activation (PA) embryos. In fertilized embryos, only maternal pronuclei carried the canonical H4K20me3 peripheral nucleolar ring-like signature. H4K20me3 disappeared at the 2-cell stage and reappeared in fertilized embryos at the 8-cell stage and in NT and PA embryos at the 4-cell stage. H4K20me3 intensity in 4-cell, 8-cell, and morula stages of fertilized embryos was significantly lower than in NT and PA embryos, suggesting aberrant regulation of H4K20me3 in PA and NT embryos. Indeed, RNA expression of the H4K20 methyltransferase Suv4-20h2 in 4-cell fertilized embryos was significantly lower than NT embryos. Knockdown of Suv4-20h2 in NT embryos rescued the H4K20me3 pattern similar to fertilized embryos. Compared to control NT embryos, knockdown of Suv4-20h2 in NT embryos improved blastocyst development ratios (11.1% vs. 30.5%) and full-term cloning efficiencies (0.8% vs. 5.9%). Upregulation of reprogramming factors, including Kdm4b, Kdm4d, Kdm6a, and Kdm6b, as well as ZGA-related factors, including Dux, Zscan4, and Hmgpi, was observed with Suv4-20h2 knockdown in NT embryos. Collectively, these are the first findings to demonstrate that H4K20me3 is an epigenetic barrier of NT reprogramming and begin to unravel the epigenetic mechanisms of H4K20 trimethylation in cell plasticity during natural reproduction and NT reprogramming in mice.
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Affiliation(s)
- Zhihui Liu
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life SciencesNanjing Normal UniversityNanjingChina
| | - Weiguo Wang
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life SciencesNanjing Normal UniversityNanjingChina
| | - Yuhan Xia
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life SciencesNanjing Normal UniversityNanjingChina
| | - Yuan Gao
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life SciencesNanjing Normal UniversityNanjingChina
| | - Zhisong Wang
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life SciencesNanjing Normal UniversityNanjingChina
| | - Mingyang Li
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life SciencesNanjing Normal UniversityNanjingChina
| | | | - Liyou An
- Xinjiang Key Laboratory of Biological Resources and Genetic Engineering, College of Life Science and TechnologyXinjiang UniversityUrumqiChina
| | - Fuliang Du
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life SciencesNanjing Normal UniversityNanjingChina
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Chavan A, Isenhart R, Nguyen SC, Kotb N, Harke J, Sintsova A, Ulukaya G, Uliana F, Ashiono C, Kutay U, Pegoraro G, Rangan P, Joyce EF, Jagannathan M. A nuclear architecture screen in Drosophila identifies Stonewall as a link between chromatin position at the nuclear periphery and germline stem cell fate. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.17.567611. [PMID: 38014085 PMCID: PMC10680830 DOI: 10.1101/2023.11.17.567611] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2023]
Abstract
The association of genomic loci to the nuclear periphery is proposed to facilitate cell-type specific gene repression and influence cell fate decisions. However, the interplay between gene position and expression remains incompletely understood, in part because the proteins that position genomic loci at the nuclear periphery remain unidentified. Here, we used an Oligopaint-based HiDRO screen targeting ~1000 genes to discover novel regulators of nuclear architecture in Drosophila cells. We identified the heterochromatin-associated protein, Stonewall (Stwl), as a factor promoting perinuclear chromatin positioning. In female germline stem cells (GSCs), Stwl binds and positions chromatin loci, including GSC differentiation genes, at the nuclear periphery. Strikingly, Stwl-dependent perinuclear positioning is associated with transcriptional repression, highlighting a likely mechanism for Stwl's known role in GSC maintenance and ovary homeostasis. Thus, our study identifies perinuclear anchors in Drosophila and demonstrates the importance of gene repression at the nuclear periphery for cell fate.
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Affiliation(s)
- Ankita Chavan
- Institute of Biochemistry, Department of Biology, ETH Zürich, Switzerland
- Bringing Materials to Life Consortium, ETH Zürich, Switzerland
- Life Science Zurich Graduate School, Zürich, Switzerland
- These authors contributed equally
| | - Randi Isenhart
- Penn Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
- These authors contributed equally
| | - Son C. Nguyen
- Penn Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Noor Kotb
- Department of Cell, Developmental and Regenerative Biology, Black Family Stem Cell Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Jailynn Harke
- Penn Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Anna Sintsova
- Institute of Microbiology, Department of Biology, ETH Zürich, Switzerland
| | - Gulay Ulukaya
- Bioinformatics for Next Generation Sequencing (BiNGS) core, Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Federico Uliana
- Institute of Biochemistry, Department of Biology, ETH Zürich, Switzerland
| | - Caroline Ashiono
- Institute of Biochemistry, Department of Biology, ETH Zürich, Switzerland
| | - Ulrike Kutay
- Institute of Biochemistry, Department of Biology, ETH Zürich, Switzerland
| | - Gianluca Pegoraro
- High Throughput Imaging Facility (HiTIF), National Cancer Institute, NIH, Bethesda, MD 20892 USA
| | - Prashanth Rangan
- Department of Cell, Developmental and Regenerative Biology, Black Family Stem Cell Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Eric F. Joyce
- Penn Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Madhav Jagannathan
- Institute of Biochemistry, Department of Biology, ETH Zürich, Switzerland
- Bringing Materials to Life Consortium, ETH Zürich, Switzerland
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Liu Z, Li M, Sun Y, Wang W, Wang Z, Presicce GA, An L, Du F. Epigenetic dynamics of H4K20me3 modification during oocyte maturation and early reprogramming of somatic cell nuclear transfer goat embryos. Am J Transl Res 2022; 14:5941-5951. [PMID: 36105059 PMCID: PMC9452338] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Accepted: 08/22/2022] [Indexed: 06/15/2023]
Abstract
OBJECTIVE We examined the epigenetic dynamics of histone H4K20 trimethylation (H4K20me3), a repressive signature in heterochromatin, during goat oocyte meiosis and the reprogramming of somatic cell nuclear transfer (NT) embryos through the first three cell divisions. METHODS Following NT, oocytes were treated with parthenogenetic activation (PA), by 5 µM calcium ionophore A23187 for 5 min followed by incubation in 2.0 mM 6-dimethylaminopurine with 5 µg/mL cycloheximide for 4 h. NT embryos up to 8-celled stage were incubated with H4K20me3 antibody. RESULTS Immunofluorescence microscopy revealed the existence of a persistent H4K20me3 signature during oocyte maturation from germinal vesicle phase to metaphase I, anaphase I, telophase I, and metaphase II, with a gradual reduction in staining intensity. NT embryos at the 2-, 4- and 8-celled stage showed lower H4K20me3 intensity than PA and IVF embryos (P < 0.05). CONCLUSION These results indicate that NT embryos exhibit insufficient H4K20me3 modification compared with IVF and PA embryos during early reprogramming, suggesting the existence of a resistant memory of differentiated cell nuclear architecture. These findings help unravel the epigenetic mechanism of histone H4K20me3 in goat nuclear transfer reprogramming.
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Affiliation(s)
- Zhihui Liu
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal UniversityNanjing 210046, Jiangsu, PR China
| | - Mingyang Li
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal UniversityNanjing 210046, Jiangsu, PR China
| | - Yu Sun
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal UniversityNanjing 210046, Jiangsu, PR China
| | - Weiguo Wang
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal UniversityNanjing 210046, Jiangsu, PR China
| | - Zhisong Wang
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal UniversityNanjing 210046, Jiangsu, PR China
| | | | - Liyou An
- Xinjiang Key Laboratory of Biological Resources and Genetic Engineering, College of Life Science and Technology, Xinjiang UniversityUrumqi 830046, Xinjiang, PR China
| | - Fuliang Du
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal UniversityNanjing 210046, Jiangsu, PR China
- Renova Life Inc., College ParkMaryland 20742, USA
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Zykova T, Maltseva M, Goncharov F, Boldyreva L, Pokholkova G, Kolesnikova T, Zhimulev I. The Organization of Pericentromeric Heterochromatin in Polytene Chromosome 3 of the Drosophilamelanogaster Line with the Rif11; SuURES Su(var)3-906 Mutations Suppressing Underreplication. Cells 2021; 10:2809. [PMID: 34831030 PMCID: PMC8616060 DOI: 10.3390/cells10112809] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Revised: 10/11/2021] [Accepted: 10/14/2021] [Indexed: 11/17/2022] Open
Abstract
Although heterochromatin makes up 40% of the Drosophila melanogaster genome, its organization remains little explored, especially in polytene chromosomes, as it is virtually not represented in them due to underreplication. Two all-new approaches were used in this work: (i) with the use of a newly synthesized Drosophila line that carries three mutations, Rif11, SuURES and Su(var)3-906, suppressing the underreplication of heterochromatic regions, we obtained their fullest representation in polytene chromosomes and described their structure; (ii) 20 DNA fragments with known positions on the physical map as well as molecular genetic features of the genome (gene density, histone marks, heterochromatin proteins, origin recognition complex proteins, replication timing sites and satellite DNAs) were mapped in the newly polytenized heterochromatin using FISH and bioinformatics data. The borders of the heterochromatic regions and variations in their positions on arm 3L have been determined for the first time. The newly polytenized heterochromatic material exhibits two main types of morphology: a banding pattern (locations of genes and short satellites) and reticular chromatin (locations of large blocks of satellite DNA). The locations of the banding and reticular polytene heterochromatin was determined on the physical map.
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Affiliation(s)
- Tatyana Zykova
- Laboratory of Molecular Cytogenetics, Institute of Molecular and Cellular Biology SB RAS, 630090 Novosibirsk, Russia; (T.Z.); (M.M.); (F.G.); (L.B.); (G.P.); (T.K.)
| | - Mariya Maltseva
- Laboratory of Molecular Cytogenetics, Institute of Molecular and Cellular Biology SB RAS, 630090 Novosibirsk, Russia; (T.Z.); (M.M.); (F.G.); (L.B.); (G.P.); (T.K.)
| | - Fedor Goncharov
- Laboratory of Molecular Cytogenetics, Institute of Molecular and Cellular Biology SB RAS, 630090 Novosibirsk, Russia; (T.Z.); (M.M.); (F.G.); (L.B.); (G.P.); (T.K.)
| | - Lidia Boldyreva
- Laboratory of Molecular Cytogenetics, Institute of Molecular and Cellular Biology SB RAS, 630090 Novosibirsk, Russia; (T.Z.); (M.M.); (F.G.); (L.B.); (G.P.); (T.K.)
| | - Galina Pokholkova
- Laboratory of Molecular Cytogenetics, Institute of Molecular and Cellular Biology SB RAS, 630090 Novosibirsk, Russia; (T.Z.); (M.M.); (F.G.); (L.B.); (G.P.); (T.K.)
| | - Tatyana Kolesnikova
- Laboratory of Molecular Cytogenetics, Institute of Molecular and Cellular Biology SB RAS, 630090 Novosibirsk, Russia; (T.Z.); (M.M.); (F.G.); (L.B.); (G.P.); (T.K.)
- Laboratory of Structural, Functional and Comparative Genomics Novosibirsk State University, 630090 Novosibirsk, Russia
| | - Igor Zhimulev
- Laboratory of Molecular Cytogenetics, Institute of Molecular and Cellular Biology SB RAS, 630090 Novosibirsk, Russia; (T.Z.); (M.M.); (F.G.); (L.B.); (G.P.); (T.K.)
- Laboratory of Structural, Functional and Comparative Genomics Novosibirsk State University, 630090 Novosibirsk, Russia
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6
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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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7
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Kochanova NY, Schauer T, Mathias GP, Lukacs A, Schmidt A, Flatley A, Schepers A, Thomae AW, Imhof A. A multi-layered structure of the interphase chromocenter revealed by proximity-based biotinylation. Nucleic Acids Res 2020; 48:4161-4178. [PMID: 32182352 PMCID: PMC7192626 DOI: 10.1093/nar/gkaa145] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Revised: 02/18/2020] [Accepted: 02/25/2020] [Indexed: 12/26/2022] Open
Abstract
During interphase centromeres often coalesce into a small number of chromocenters, which can be visualized as distinct, DAPI dense nuclear domains. Intact chromocenters play a major role in maintaining genome stability as they stabilize the transcriptionally silent state of repetitive DNA while ensuring centromere function. Despite its biological importance, relatively little is known about the molecular composition of the chromocenter or the processes that mediate chromocenter formation and maintenance. To provide a deeper molecular insight into the composition of the chromocenter and to demonstrate the usefulness of proximity-based biotinylation as a tool to investigate those questions, we performed super resolution microscopy and proximity-based biotinylation experiments of three distinct proteins associated with the chromocenter in Drosophila. Our work revealed an intricate internal architecture of the chromocenter suggesting a complex multilayered structure of this intranuclear domain.
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Affiliation(s)
- Natalia Y Kochanova
- Biomedical Center, Chromatin Proteomics Group, Department of Molecular Biology, Faculty of Medicine, Ludwig-Maximilians-Universität München, Großhaderner Strasse 9, 82152 Planegg-Martinsried, Germany
| | - Tamas Schauer
- Biomedical Center, Bioinformatics Core Facility, Ludwig-Maximilians-Universität München, Großhaderner Strasse 9, 82152 Planegg-Martinsried, Germany
| | - Grusha Primal Mathias
- Biomedical Center, Core Facility Bioimaging, Ludwig-Maximilians-Universität München, Großhaderner Strasse 9, 82152 Planegg-Martinsried, Germany
| | - Andrea Lukacs
- Biomedical Center, Chromatin Proteomics Group, Department of Molecular Biology, Faculty of Medicine, Ludwig-Maximilians-Universität München, Großhaderner Strasse 9, 82152 Planegg-Martinsried, Germany
| | - Andreas Schmidt
- Biomedical Center, Protein Analysis Unit, Faculty of Medicine, Ludwig-Maximilians-Universität München, Großhaderner Strasse 9, 82152 Planegg-Martinsried, Germany
| | - Andrew Flatley
- Helmholtz Zentrum München, Deutsches Forschungszentrum für Gesundheit und Umwelt (GmbH), Institute for Diabetes and Obesity, Monoclonal Antibody Core Facility and Research Group Ingolstädter Landstr. 1, 85764 Neuherberg, Germany
| | - Aloys Schepers
- Helmholtz Zentrum München, Deutsches Forschungszentrum für Gesundheit und Umwelt (GmbH), Institute for Diabetes and Obesity, Monoclonal Antibody Core Facility and Research Group Ingolstädter Landstr. 1, 85764 Neuherberg, Germany
| | - Andreas W Thomae
- Biomedical Center, Core Facility Bioimaging, Ludwig-Maximilians-Universität München, Großhaderner Strasse 9, 82152 Planegg-Martinsried, Germany
| | - Axel Imhof
- Biomedical Center, Chromatin Proteomics Group, Department of Molecular Biology, Faculty of Medicine, Ludwig-Maximilians-Universität München, Großhaderner Strasse 9, 82152 Planegg-Martinsried, Germany
- Biomedical Center, Protein Analysis Unit, Faculty of Medicine, Ludwig-Maximilians-Universität München, Großhaderner Strasse 9, 82152 Planegg-Martinsried, Germany
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8
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Swenson JM, Colmenares SU, Strom AR, Costes SV, Karpen GH. The composition and organization of Drosophila heterochromatin are heterogeneous and dynamic. eLife 2016; 5. [PMID: 27514026 PMCID: PMC4981497 DOI: 10.7554/elife.16096] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Accepted: 07/06/2016] [Indexed: 12/13/2022] Open
Abstract
Heterochromatin is enriched for specific epigenetic factors including Heterochromatin Protein 1a (HP1a), and is essential for many organismal functions. To elucidate heterochromatin organization and regulation, we purified Drosophila melanogaster HP1a interactors, and performed a genome-wide RNAi screen to identify genes that impact HP1a levels or localization. The majority of the over four hundred putative HP1a interactors and regulators identified were previously unknown. We found that 13 of 16 tested candidates (83%) are required for gene silencing, providing a substantial increase in the number of identified components that impact heterochromatin properties. Surprisingly, image analysis revealed that although some HP1a interactors and regulators are broadly distributed within the heterochromatin domain, most localize to discrete subdomains that display dynamic localization patterns during the cell cycle. We conclude that heterochromatin composition and architecture is more spatially complex and dynamic than previously suggested, and propose that a network of subdomains regulates diverse heterochromatin functions.
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Affiliation(s)
- Joel M Swenson
- Division of Biological Systems and Engineering, Lawrence Berkeley National Laboratory, Berkeley, United States
| | - Serafin U Colmenares
- Division of Biological Systems and Engineering, Lawrence Berkeley National Laboratory, Berkeley, United States
| | - Amy R Strom
- Division of Biological Systems and Engineering, Lawrence Berkeley National Laboratory, Berkeley, United States.,Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States
| | - Sylvain V Costes
- Division of Biological Systems and Engineering, Lawrence Berkeley National Laboratory, Berkeley, United States
| | - Gary H Karpen
- Division of Biological Systems and Engineering, Lawrence Berkeley National Laboratory, Berkeley, United States.,Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States
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9
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Coulthard AB, Taylor-Kamall RW, Hallson G, Axentiev A, Sinclair DA, Honda BM, Hilliker AJ. Meiotic recombination is suppressed near the histone-defined border of euchromatin and heterochromatin on chromosome 2L of Drosophila melanogaster. Genome 2016; 59:289-94. [DOI: 10.1139/gen-2015-0171] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In Drosophila melanogaster, the borders between pericentric heterochromatin and euchromatin on the major chromosome arms have been defined in various ways, including chromatin-specific histone modifications, the binding patterns of heterochromatin-enriched chromosomal proteins, and various cytogenetic techniques. Elucidation of the genetic properties that independently define the different chromatin states associated with heterochromatin and euchromatin should help refine the boundary. Since meiotic recombination is present in euchromatin, but absent in heterochromatin, it constitutes a key genetic property that can be observed transitioning between chromatin states. Using P element insertion lines marked with a su(Hw) insulated mini-white gene, meiotic recombination was found to transition in a region consistent with the H3K9me2 transition observed in ovaries.
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Affiliation(s)
| | | | - Graham Hallson
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC V5A 1S6, Canada
| | - Anna Axentiev
- Department of Biology, York University, Toronto, ON M3J 1P3, Canada
| | - Don A. Sinclair
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC V5A 1S6, Canada
| | - Barry M. Honda
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC V5A 1S6, Canada
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10
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Rao Z, Duan J, Xia Q, Feng Q. In silico identification of BESS-DC genes and expression analysis in the silkworm, Bombyx mori. Gene 2016; 575:478-487. [DOI: 10.1016/j.gene.2015.09.024] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Revised: 09/10/2015] [Accepted: 09/11/2015] [Indexed: 11/15/2022]
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11
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Simon JM, Parker JS, Liu F, Rothbart SB, Ait-Si-Ali S, Strahl BD, Jin J, Davis IJ, Mosley AL, Pattenden SG. A Role for Widely Interspaced Zinc Finger (WIZ) in Retention of the G9a Methyltransferase on Chromatin. J Biol Chem 2015; 290:26088-102. [PMID: 26338712 PMCID: PMC4646261 DOI: 10.1074/jbc.m115.654459] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2015] [Revised: 08/23/2015] [Indexed: 11/06/2022] Open
Abstract
G9a and GLP lysine methyltransferases form a heterodimeric complex that is responsible for the majority of histone H3 lysine 9 mono- and di-methylation (H3K9me1/me2). Widely interspaced zinc finger (WIZ) associates with the G9a-GLP protein complex, but its role in mediating lysine methylation is poorly defined. Here, we show that WIZ regulates global H3K9me2 levels by facilitating the interaction of G9a with chromatin. Disrupting the association of G9a-GLP with chromatin by depleting WIZ resulted in altered gene expression and protein-protein interactions that were distinguishable from that of small molecule-based inhibition of G9a/GLP, supporting discrete functions of the G9a-GLP-WIZ chromatin complex in addition to H3K9me2 methylation.
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Affiliation(s)
- Jeremy M Simon
- From the Carolina Institute for Developmental Disabilities, Department of Cell Biology and Physiology, and the Department of Genetics, Curriculum in Bioinformatics and Computational Biology, Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Joel S Parker
- the Department of Genetics and the Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Feng Liu
- the Center for Integrative Chemical Biology and Drug Discovery, Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, Chapel Hill, North Carolina 27599
| | - Scott B Rothbart
- the Center for Epigenetics, Van Andel Research Institute, Grand Rapids, Michigan 49503
| | - Slimane Ait-Si-Ali
- the Laboratoire Epigénétique et Destin Cellulaire, UMR7216, CNRS, Université Paris Diderot, Sorbonne Paris Cité, 75013 Paris, France
| | - Brian D Strahl
- the Lineberger Comprehensive Cancer Center, the Curriculum in Genetics and Molecular Biology, and the Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Jian Jin
- the Department of Structural and Chemical Biology, the Department of Oncological Sciences, and the Department of Pharmacology and Systems Therapeutics, Icahn School of Medicine at Mount Sinai, New York, New York 10029
| | - Ian J Davis
- the Department of Genetics, the Lineberger Comprehensive Cancer Center, the Department of Pediatrics, and the Carolina Center for Genome Sciences, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, and
| | - Amber L Mosley
- the Department of Biochemistry and Molecular Biology and the Center for Computational Biology and Bioinformatics, Indiana University School of Medicine, Indianapolis, Indiana 46202
| | - Samantha G Pattenden
- the Center for Integrative Chemical Biology and Drug Discovery, Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, Chapel Hill, North Carolina 27599,
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12
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Basquin D, Spierer A, Begeot F, Koryakov DE, Todeschini AL, Ronsseray S, Vieira C, Spierer P, Delattre M. The Drosophila Su(var)3-7 gene is required for oogenesis and female fertility, genetically interacts with piwi and aubergine, but impacts only weakly transposon silencing. PLoS One 2014; 9:e96802. [PMID: 24820312 PMCID: PMC4018442 DOI: 10.1371/journal.pone.0096802] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Accepted: 04/11/2014] [Indexed: 11/19/2022] Open
Abstract
Heterochromatin is made of repetitive sequences, mainly transposable elements (TEs), the regulation of which is critical for genome stability. We have analyzed the role of the heterochromatin-associated Su(var)3-7 protein in Drosophila ovaries. We present evidences that Su(var)3-7 is required for correct oogenesis and female fertility. It accumulates in heterochromatic domains of ovarian germline and somatic cells nuclei, where it co-localizes with HP1. Homozygous mutant females display ovaries with frequent degenerating egg-chambers. Absence of Su(var)3-7 in embryos leads to defects in meiosis and first mitotic divisions due to chromatin fragmentation or chromosome loss, showing that Su(var)3-7 is required for genome integrity. Females homozygous for Su(var)3-7 mutations strongly impair repression of P-transposable element induced gonadal dysgenesis but have minor effects on other TEs. Su(var)3-7 mutations reduce piRNA cluster transcription and slightly impact ovarian piRNA production. However, this modest piRNA reduction does not correlate with transposon de-silencing, suggesting that the moderate effect of Su(var)3-7 on some TE repression is not linked to piRNA production. Strikingly, Su(var)3-7 genetically interacts with the piwi and aubergine genes, key components of the piRNA pathway, by strongly impacting female fertility without impairing transposon silencing. These results lead us to propose that the interaction between Su(var)3-7 and piwi or aubergine controls important developmental processes independently of transposon silencing.
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Affiliation(s)
- Denis Basquin
- Department of Genetics and Evolution, University of Geneva, Geneva, Switzerland
| | - Anne Spierer
- Department of Genetics and Evolution, University of Geneva, Geneva, Switzerland
| | - Flora Begeot
- Department of Genetics and Evolution, University of Geneva, Geneva, Switzerland
| | | | - Anne-Laure Todeschini
- Laboratoire Biologie du Développement, UMR7622, CNRS-Université Pierre et Marie Curie, Paris, France
| | - Stéphane Ronsseray
- Laboratoire Biologie du Développement, UMR7622, CNRS-Université Pierre et Marie Curie, Paris, France
| | - Cristina Vieira
- Laboratoire de Biométrie et Biologie Evolutive, UMR5558, Université Lyon1, Villeurbanne, France
- Institut Universitaire de France, Paris, France
| | - Pierre Spierer
- Department of Genetics and Evolution, University of Geneva, Geneva, Switzerland
| | - Marion Delattre
- Department of Genetics and Evolution, University of Geneva, Geneva, Switzerland
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13
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Dangwal M, Kapoor S, Kapoor M. The PpCMT chromomethylase affects cell growth and interacts with the homolog of LIKE HETEROCHROMATIN PROTEIN 1 in the moss Physcomitrella patens. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2014; 77:589-603. [PMID: 24329971 DOI: 10.1111/tpj.12406] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2013] [Revised: 11/30/2013] [Accepted: 12/03/2013] [Indexed: 05/06/2023]
Abstract
Chromomethylases (CMTs) are plant-specific cytosine DNA methyltransferases that are involved in maintenance of CpNpG methylation. In seed plants, histone methylation and interaction of CMT with LIKE HETEROCHROMATIN PROTEIN 1 (LHP1) is essential for recruitment of CMT to target sites. LHP1 has been characterized as a putative component of the POLYCOMB REPRESSIVE COMPLEX1 (PRC1) in plants, and functions downstream of PRC2 to maintain genes in repressed state for orchestrated development. In the present study, we show that targeted disruption of PpCMT results in an approximately 50% reduction in global cytosine methylation levels. This affects growth of apical cells, predominantly growth of side branch initials emerging from chloronema cells. In some places, these cells develop thick walls with plasmolyzed cellular contents. Transcript accumulation patterns of genes involved in apical cell extension and metabolism of hemicelluloses, such as xyloglucans, in the primary cell walls decreased many fold in ppcmt mutant lines, as determined by real-time PCR. Using yeast two-hybrid method and bimolecular fluorescence complementation assay, we show that PpCMT and PpLHP1 interact through their chromo domains, while PpLHP1 homodimerizes through its chromo shadow domain. The results presented in this study provide insight into the role of the single chromomethylase, PpCMT, in proliferation of protonema filaments, and shed light on the evolutionary conservation of proteins interacting with these methylases in the early land plant, Physcomitrella patens.
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Affiliation(s)
- Meenakshi Dangwal
- University School of Biotechnology, Guru Gobind Singh Indraprastha University, Sector 16C, Dwarka, New Delhi, 110078, India
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14
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Elgin SCR, Reuter G. Position-effect variegation, heterochromatin formation, and gene silencing in Drosophila. Cold Spring Harb Perspect Biol 2013; 5:a017780. [PMID: 23906716 DOI: 10.1101/cshperspect.a017780] [Citation(s) in RCA: 309] [Impact Index Per Article: 28.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Position-effect variegation (PEV) results when a gene normally in euchromatin is juxtaposed with heterochromatin by rearrangement or transposition. When heterochromatin packaging spreads across the heterochromatin/euchromatin border, it causes transcriptional silencing in a stochastic pattern. PEV is intensely studied in Drosophila using the white gene. Screens for dominant mutations that suppress or enhance white variegation have identified many conserved epigenetic factors, including the histone H3 lysine 9 methyltransferase SU(VAR)3-9. Heterochromatin protein HP1a binds H3K9me2/3 and interacts with SU(VAR)3-9, creating a core memory system. Genetic, molecular, and biochemical analysis of PEV in Drosophila has contributed many key findings concerning establishment and maintenance of heterochromatin with concomitant gene silencing.
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Affiliation(s)
- Sarah C R Elgin
- Department of Biology, Washington University, St. Louis, Missouri 63130, USA.
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15
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Mendez DL, Mandt RE, Elgin SCR. Heterochromatin Protein 1a (HP1a) partner specificity is determined by critical amino acids in the chromo shadow domain and C-terminal extension. J Biol Chem 2013; 288:22315-23. [PMID: 23793104 DOI: 10.1074/jbc.m113.468413] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Drosophila melanogaster Heterochromatin Protein 1a (HP1a) is an essential protein critical for heterochromatin assembly and regulation. Its chromo shadow domain (CSD) homodimerizes, a requirement for binding protein partners that contain a PXVXL motif. How does HP1a select among its many different PXVXL-containing partners? HP1a binds tightly to Heterochromatin Protein 2 (HP2), but weakly to PIWI. We investigated differences in homodimerization and the impact of the C-terminal extension (CTE) by contrasting HP1a to its paralogue, HP1b. HP1a and HP1b differ in the dimerization interface, with HP1a having an Arg at position 188 rather than Glu. We find that while this substitution reduces the dimerization constant, it does not impact the binding surface as demonstrated by unchanged partner binding affinities. However, the CTE (only 4 residues in HP1a as compared with 87 residues in HP1b) is critical; the charged residues in HP1a are necessary for tight peptide binding. Examining a panel of amino acid substitutions in the HP1a CSD, we find that Leu-165 in HP1a interacts with HP2 but not PIWI, supporting the conclusion that different sites in the binding surface provide discrimination for partner selection. Partner sequence is also critical for affinity, as the remaining difference in binding between HP2 and PIWI polypeptides is eliminated by swapping the PXVXL motifs between the two. Taken together, these studies indicate that the binding surface of the HP1a CSD plus its short CTE provide the needed discrimination among HP1a's partners, and that the CTE is important for differentiating the interactions of the Drosophila HP1 paralogs.
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Affiliation(s)
- Deanna L Mendez
- Department of Biology, Washington University, Saint Louis, Missouri 63130, USA
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16
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Chromatin-associated proteins HP1 and Mod(mdg4) modify Y-linked regulatory variation in the drosophila testis. Genetics 2013; 194:609-18. [PMID: 23636736 DOI: 10.1534/genetics.113.150805] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Chromatin remodeling is crucial for gene regulation. Remodeling is often mediated through chemical modifications of the DNA template, DNA-associated proteins, and RNA-mediated processes. Y-linked regulatory variation (YRV) refers to the quantitative effects that polymorphic tracts of Y-linked chromatin exert on gene expression of X-linked and autosomal genes. Here we show that naturally occurring polymorphisms in the Drosophila melanogaster Y chromosome contribute disproportionally to gene expression variation in the testis. The variation is dependent on wild-type expression levels of mod(mdg4) as well as Su(var)205; the latter gene codes for heterochromatin protein 1 (HP1) in Drosophila. Testis-specific YRV is abolished in genotypes with heterozygous loss-of-function mutations for mod(mdg4) and Su(var)205 but not in similar experiments with JIL-1. Furthermore, the Y chromosome differentially regulates several ubiquitously expressed genes. The results highlight the requirement for wild-type dosage of Su(var)205 and mod(mdg4) in enabling naturally occurring Y-linked regulatory variation in the testis. The phenotypes that emerge in the context of wild-type levels of the HP1 and Mod(mdg4) proteins might be part of an adaptive response to the environment.
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17
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Abstract
Maintenance of genome integrity, cell division and gene expression have all been shown to be regulated by the condensation of DNA into heterochromatin. In a study published in this issue, Bulut-Karslioglu et al. reveal a new heterochromatin function for transcription factors in a mammalian system. They show that instead of activating gene expression, in the context of heterochromatic repeats, specific transcription factors are necessary for the maintenance of transcriptional repression and heterochromatin.
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18
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Kowalski A, Pałyga J. Chromatin compaction in terminally differentiated avian blood cells: the role of linker histone H5 and non-histone protein MENT. Chromosome Res 2011; 19:579-90. [PMID: 21656257 PMCID: PMC3139888 DOI: 10.1007/s10577-011-9218-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2011] [Revised: 05/04/2011] [Accepted: 05/06/2011] [Indexed: 10/28/2022]
Abstract
Chromatin has a tendency to shift from a relatively decondensed (active) to condensed (inactive) state during cell differentiation due to interactions of specific architectural and/or regulatory proteins with DNA. A promotion of chromatin folding in terminally differentiated avian blood cells requires the presence of either histone H5 in erythrocytes or non-histone protein, myeloid and erythroid nuclear termination stage-specific protein (MENT), in white blood cells (lymphocytes and granulocytes). These highly abundant proteins assist in folding of nucleosome arrays and self-association of chromatin fibers into compacted chromatin structures. Here, we briefly review structural aspects and molecular mode of action by which these unrelated proteins can spread condensed chromatin to form inactivated regions in the genome.
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Affiliation(s)
- Andrzej Kowalski
- Department of Biochemistry and Genetics, Institute of Biology, Jan Kochanowski University, ul. Świętokrzyska 15, 25-406 Kielce, Poland.
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19
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Kwon SH, Workman JL. The changing faces of HP1: From heterochromatin formation and gene silencing to euchromatic gene expression: HP1 acts as a positive regulator of transcription. Bioessays 2011; 33:280-9. [PMID: 21271610 DOI: 10.1002/bies.201000138] [Citation(s) in RCA: 120] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Heterochromatin protein 1 (HP1) is a positive regulator of active transcription in euchromatin. HP1 was first identified in Drosophila melanogaster as a major component of heterochromatin. Most eukaryotes have at least three isoforms of HP1, which are conserved in overall structure but localize differentially to heterochromatin and euchromatin. Although initial studies revealed a key role for HP1 in heterochromatin formation and gene silencing, recent progress has shed light on additional roles for HP1 in processes such as euchromatic gene expression. Recent studies have highlighted the importance of HP1-mediated gene regulation in euchromatin. Here, we focus on recent advances in understanding the role of HP1 in active transcription in euchromatin and how modification and localization of HP1 can regulate distinct functions for this protein in different contexts.
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Affiliation(s)
- So Hee Kwon
- Stowers Institute for Medical Research, Kansas City, MO, USA
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20
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Riddle NC, Minoda A, Kharchenko PV, Alekseyenko AA, Schwartz YB, Tolstorukov MY, Gorchakov AA, Jaffe JD, Kennedy C, Linder-Basso D, Peach SE, Shanower G, Zheng H, Kuroda MI, Pirrotta V, Park PJ, Elgin SC, Karpen GH. Plasticity in patterns of histone modifications and chromosomal proteins in Drosophila heterochromatin. Genome Res 2011; 21:147-63. [PMID: 21177972 PMCID: PMC3032919 DOI: 10.1101/gr.110098.110] [Citation(s) in RCA: 214] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2010] [Accepted: 12/08/2010] [Indexed: 12/18/2022]
Abstract
Eukaryotic genomes are packaged in two basic forms, euchromatin and heterochromatin. We have examined the composition and organization of Drosophila melanogaster heterochromatin in different cell types using ChIP-array analysis of histone modifications and chromosomal proteins. As anticipated, the pericentric heterochromatin and chromosome 4 are on average enriched for the "silencing" marks H3K9me2, H3K9me3, HP1a, and SU(VAR)3-9, and are generally depleted for marks associated with active transcription. The locations of the euchromatin-heterochromatin borders identified by these marks are similar in animal tissues and most cell lines, although the amount of heterochromatin is variable in some cell lines. Combinatorial analysis of chromatin patterns reveals distinct profiles for euchromatin, pericentric heterochromatin, and the 4th chromosome. Both silent and active protein-coding genes in heterochromatin display complex patterns of chromosomal proteins and histone modifications; a majority of the active genes exhibit both "activation" marks (e.g., H3K4me3 and H3K36me3) and "silencing" marks (e.g., H3K9me2 and HP1a). The hallmark of active genes in heterochromatic domains appears to be a loss of H3K9 methylation at the transcription start site. We also observe complex epigenomic profiles of intergenic regions, repeated transposable element (TE) sequences, and genes in the heterochromatic extensions. An unexpectedly large fraction of sequences in the euchromatic chromosome arms exhibits a heterochromatic chromatin signature, which differs in size, position, and impact on gene expression among cell types. We conclude that patterns of heterochromatin/euchromatin packaging show greater complexity and plasticity than anticipated. This comprehensive analysis provides a foundation for future studies of gene activity and chromosomal functions that are influenced by or dependent upon heterochromatin.
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Affiliation(s)
- Nicole C. Riddle
- Department of Biology, Washington University St. Louis, Missouri 63130, USA
| | - Aki Minoda
- Department of Molecular and Cell Biology, University of California at Berkeley and Department of Genome Dynamics, Lawrence Berkeley National Lab, Berkeley, California 94720, USA
| | - Peter V. Kharchenko
- Center for Biomedical Informatics, Harvard Medical School and Informatics Program, Children's Hospital, Boston, Massachusetts 02115, USA
| | - Artyom A. Alekseyenko
- Division of Genetics, Department of Medicine, Brigham & Women's Hospital, and Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Yuri B. Schwartz
- Department of Molecular Biology & Biochemistry, Rutgers University, Piscataway, New Jersey 08901, USA
- Department of Molecular Biology, Umea University, 90187 Umea, Sweden
| | - Michael Y. Tolstorukov
- Center for Biomedical Informatics, Harvard Medical School and Informatics Program, Children's Hospital, Boston, Massachusetts 02115, USA
| | - Andrey A. Gorchakov
- Division of Genetics, Department of Medicine, Brigham & Women's Hospital, and Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Jacob D. Jaffe
- Proteomics Group, The Broad Institute, Cambridge, Massachusetts 02139, USA
| | - Cameron Kennedy
- Department of Molecular and Cell Biology, University of California at Berkeley and Department of Genome Dynamics, Lawrence Berkeley National Lab, Berkeley, California 94720, USA
| | - Daniela Linder-Basso
- Department of Molecular Biology & Biochemistry, Rutgers University, Piscataway, New Jersey 08901, USA
| | - Sally E. Peach
- Proteomics Group, The Broad Institute, Cambridge, Massachusetts 02139, USA
| | - Gregory Shanower
- Department of Molecular Biology & Biochemistry, Rutgers University, Piscataway, New Jersey 08901, USA
| | - Haiyan Zheng
- Biological Mass Spectrometry Resource, Center for Advanced Biotechnology and Medicine, University of Dentistry and Medicine of New Jersey, Piscataway, New Jersey 08854, USA
| | - Mitzi I. Kuroda
- Division of Genetics, Department of Medicine, Brigham & Women's Hospital, and Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Vincenzo Pirrotta
- Department of Molecular Biology & Biochemistry, Rutgers University, Piscataway, New Jersey 08901, USA
| | - Peter J. Park
- Center for Biomedical Informatics, Harvard Medical School and Informatics Program, Children's Hospital, Boston, Massachusetts 02115, USA
| | - Sarah C.R. Elgin
- Department of Biology, Washington University St. Louis, Missouri 63130, USA
| | - Gary H. Karpen
- Department of Molecular and Cell Biology, University of California at Berkeley and Department of Genome Dynamics, Lawrence Berkeley National Lab, Berkeley, California 94720, USA
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21
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Abstract
Genetic screens in Drosophila have been instrumental in distinguishing approximately 390 loci involved in position effect variegation and heterochromatin stabilization. Most of the identified genes [so-called Su(var) and E(var) genes] are also conserved in mammals, where more than 50 of their gene products are known to localize to constitutive heterochromatin. From these proteins, approximately 12 core heterochromatin components can be inferred. In addition, there are approximately 30 additional Su(var) and 10 E(var) factors that can, under distinct developmental options, interchange with constitutive heterochromatin and participate in the partitioning of the genome into repressed and active chromatin domains. A significant fraction of the Su(var) and E(var) factors are enzymes that respond to environmental and metabolic signals, thereby allowing both the variation and propagation of epigenetic states to a dynamic chromatin template. Moreover, the misregulation of human SU(VAR) and E(VAR) function can advance cancer and many other human diseases including more complex disorders. As such, mammalian Su(var) and E(var) genes and their products provide a rich source of novel targets for diagnosis of and pharmaceutical intervention in many human diseases.
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Affiliation(s)
- Barna D Fodor
- Max-Planck Institute of Immunobiology, D-79108 Freiburg, Germany.
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22
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JIL-1 and Su(var)3-7 interact genetically and counteract each other's effect on position-effect variegation in Drosophila. Genetics 2010; 185:1183-92. [PMID: 20457875 DOI: 10.1534/genetics.110.117150] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The essential JIL-1 histone H3S10 kinase is a key regulator of chromatin structure that functions to maintain euchromatic domains while counteracting heterochromatization and gene silencing. In the absence of the JIL-1 kinase, two of the major heterochromatin markers H3K9me2 and HP1a spread in tandem to ectopic locations on the chromosome arms. Here we address the role of the third major heterochromatin component, the zinc-finger protein Su(var)3-7. We show that the lethality but not the chromosome morphology defects associated with the null JIL-1 phenotype to a large degree can be rescued by reducing the dose of the Su(var)3-7 gene and that Su(var)3-7 and JIL-1 loss-of-function mutations have an antagonistic and counterbalancing effect on position-effect variegation (PEV). Furthermore, we show that in the absence of JIL-1 kinase activity, Su(var)3-7 gets redistributed and upregulated on the chromosome arms. Reducing the dose of the Su(var)3-7 gene dramatically decreases this redistribution; however, the spreading of H3K9me2 to the chromosome arms was unaffected, strongly indicating that ectopic Su(var)3-9 activity is not a direct cause of lethality. These observations suggest a model where Su(var)3-7 functions as an effector downstream of Su(var)3-9 and H3K9 dimethylation in heterochromatic spreading and gene silencing that is normally counteracted by JIL-1 kinase activity.
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23
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Reo E, Seum C, Spierer P, Bontron S. Sumoylation of Drosophila SU(VAR)3-7 is required for its heterochromatic function. Nucleic Acids Res 2010; 38:4254-62. [PMID: 20299342 PMCID: PMC2910048 DOI: 10.1093/nar/gkq168] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
In Drosophila, SU(VAR)3-7 is an essential heterochromatin component. It is required for proper chromatin condensation, and changing its dose modifies position-effect variegation. Sumoylation is a post-translational modification shown to play a role in diverse biological processes. Here, we demonstrate that sumoylation is essential for proper heterochromatin function in Drosophila through modification of SU(VAR)3-7. Indeed, SU(VAR)3-7 is sumoylated at lysine K839; this modification is required for localization of SU(VAR)3-7 at pericentric heterochromatin, chromosome 4, and telomeres. In addition, sumoylation of SU(VAR)3-7 is a prerequisite for its ability to enhance position-effect variegation. Thus, these results show that the heterochromatic function of SU(VAR)3-7 depends on its own sumoylation, and unveil a role for sumoylation in Drosophila heterochromatin.
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Affiliation(s)
- Emanuela Reo
- Department of Zoology and Animal Biology, University of Geneva, quai Ernest-Ansermet 30, CH-1211 Geneva 4, Switzerland
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24
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Hofmann A, Brünner M, Schwendemann A, Strödicke M, Karberg S, Klebes A, Saumweber H, Korge G. The winged-helix transcription factor JUMU regulates development, nucleolus morphology and function, and chromatin organization of Drosophila melanogaster. Chromosome Res 2010; 18:307-24. [PMID: 20213139 DOI: 10.1007/s10577-010-9118-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2009] [Accepted: 02/05/2010] [Indexed: 01/10/2023]
Abstract
The PEV-modifying winged-helix/forkhead domain transcription factor JUMU of Drosophila is an essential protein of pleiotropic function. The correct gene dose of jumu is required for nucleolar integrity and correct nucleolus function. Overexpression of jumu results in bloating of euchromatic chromosome arms, displacement of the JUMU protein from the chromocenter and the nucleolus, fragile weak points, and disrupted chromocenter of polytene chromosomes. Overexpression of the acidic C terminus of JUMU alone causes nucleolus disorganization. In addition, euchromatic genes are overexpressed and HP1, which normally accumulates in the pericentric heterochromatin and spreads into euchromatic chromosome arms, although H3-K9 di-methylation remains restricted to the pericentric heterochromatin. The human winged-helix nude gene shows similarities to jumu and its overexpression in Drosophila causes bristle mutations.
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Affiliation(s)
- Annemarie Hofmann
- Institut für Biologie-Genetik, Freie Universität Berlin, Takustr. 6, 14195, Berlin, Germany.
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25
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Riddle NC, Shaffer CD, Elgin SCR. A lot about a little dot - lessons learned from Drosophila melanogaster chromosome 4. Biochem Cell Biol 2009; 87:229-41. [PMID: 19234537 DOI: 10.1139/o08-119] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The fourth chromosome of Drosophila melanogaster has a number of unique properties that make it a convenient model for the study of chromatin structure. Only 4.2 Mb overall, the 1.2 Mb distal arm of chromosome 4 seen in polytene chromosomes combines characteristics of heterochromatin and euchromatin. This domain has a repeat density of ~35%, comparable to some pericentric chromosome regions, while maintaining a gene density similar to that of the other euchromatic chromosome arms. Studies of position-effect variegation have revealed that heterochromatic and euchromatic domains are interspersed on chromosome 4, and both cytological and biochemical studies have demonstrated that chromosome 4 is associated with heterochromatic marks, such as heterochromatin protein 1 and histone 3 lysine 9 methylation. Chromosome 4 is also marked by POF (painting-of-fourth), a chromosome 4-specific chromosomal protein, and utilizes a dedicated histone methyltransferase, EGG. Studies of chromosome 4 have helped to shape our understanding of heterochromatin domains and their establishment and maintenance. In this review, we provide a synthesis of the work to date and an outlook to the future.
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Affiliation(s)
- Nicole C Riddle
- Department of Biology, Washington University in St. Louis, St. Louis, MO 63130, USA
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Hofmann A, Brünner M, Korge G. The winged-helix transcription factor JUMU is a haplo-suppressor/triplo-enhancer of PEV in various tissues but exhibits reverse PEV effects in the brain of Drosophila melanogaster. Chromosome Res 2009; 17:347-58. [DOI: 10.1007/s10577-009-9026-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2008] [Revised: 12/02/2008] [Accepted: 12/02/2008] [Indexed: 11/28/2022]
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27
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Eissenberg JC, Reuter G. Cellular mechanism for targeting heterochromatin formation in Drosophila. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2009; 273:1-47. [PMID: 19215901 DOI: 10.1016/s1937-6448(08)01801-7] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Near the end of their 1990 historical perspective article "60 Years of Mystery," Spradling and Karpen (1990) observe: "Recent progress in understanding variegation at the molecular level has encouraged some workers to conclude that the heterochromatization model is essentially correct and that position-effect variegation can now join the mainstream of molecular biology." In the 18 years since those words were written, heterochromatin and its associated position effects have indeed joined the mainstream of molecular biology. Here, we review the findings that led to our current understanding of heterochromatin formation in Drosophila and the mechanistic insights into heterochromatin structural and functional properties gained through molecular genetics and cytology.
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Affiliation(s)
- Joel C Eissenberg
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, Missouri, USA
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28
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Abstract
Centromeres are an essential and conserved feature of eukaryotic chromosomes, yet recent research indicates that we are just beginning to understand the numerous roles that centromeres have in chromosome segregation. During meiosis I, in particular, centromeres seem to function in many processes in addition to their canonical role in assembling kinetochores, the sites of microtubule attachment. Here we summarize recent advances that place centromeres at the centre of meiosis I, and discuss how these studies affect a variety of basic research fields and thus hold promise for increasing our understanding of human reproductive defects and disease states.
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Doheny JG, Mottus R, Grigliatti TA. Telomeric position effect--a third silencing mechanism in eukaryotes. PLoS One 2008; 3:e3864. [PMID: 19057646 PMCID: PMC2587703 DOI: 10.1371/journal.pone.0003864] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2008] [Accepted: 10/20/2008] [Indexed: 12/29/2022] Open
Abstract
Eukaryotic chromosomes terminate in telomeres, complex nucleoprotein structures that are required for chromosome integrity that are implicated in cellular senescence and cancer. The chromatin at the telomere is unique with characteristics of both heterochromatin and euchromatin. The end of the chromosome is capped by a structure that protects the end and is required for maintaining proper chromosome length. Immediately proximal to the cap are the telomere associated satellite-like (TAS) sequences. Genes inserted into the TAS sequences are silenced indicating the chromatin environment is incompatible with transcription. This silencing phenomenon is called telomeric position effect (TPE). Two other silencing mechanisms have been identified in eukaryotes, suppressors position effect variegation [Su(var)s, greater than 30 members] and Polycomb group proteins (PcG, approximately 15 members). We tested a large number of each group for their ability to suppress TPE [Su(TPE)]. Our results showed that only three Su(var)s and only one PcG member are involved in TPE, suggesting silencing in the TAS sequences occurs via a novel silencing mechanism. Since, prior to this study, only five genes have been identified that are Su(TPE)s, we conducted a candidate screen for Su(TPE) in Drosophila by testing point mutations in, and deficiencies for, proteins involved in chromatin metabolism. Screening with point mutations identified seven new Su(TPE)s and the deficiencies identified 19 regions of the Drosophila genome that harbor suppressor mutations. Chromatin immunoprecipitation experiments on a subset of the new Su(TPE)s confirm they act directly on the gene inserted into the telomere. Since the Su(TPE)s do not overlap significantly with either PcGs or Su(var)s, and the candidates were selected because they are involved generally in chromatin metabolism and act at a wide variety of sites within the genome, we propose that the Su(TPE) represent a third, widely used, silencing mechanism in the eukaryotic genome.
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Affiliation(s)
- J. Greg Doheny
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Randy Mottus
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Thomas A. Grigliatti
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada
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30
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Abstract
While heterochromatic gene silencing in cis is often accompanied by nucleosomal compaction, characteristic histone modifications, and recruitment of heterochromatin proteins, little is known concerning genes silenced by heterochromatin in trans. An insertion of heterochromatic satellite DNA in the euchromatic brown (bw) gene of Drosophila melanogaster results in bwDominant (bwD), which can inactivate loci on the homolog by relocation near the centric heterochromatin (trans-inactivation). Nucleosomal compaction was found to accompany trans-inactivation, but stereotypical heterochromatic histone modifications were mostly absent on silenced reporter genes. HP1 was enriched on trans-inactivated reporter constructs and this enrichment was more pronounced on adult chromatin than on larval chromatin. Interestingly, this HP1 enrichment in trans was unaccompanied by an increase in the 2MeH3K9 mark, which is generally thought to be the docking site for HP1 in heterochromatin. However, a substantial increase in the 2MeH3K9 mark was found on or near the bwD satellite insertion in cis, but did not spread further. These observations suggest that the interaction of HP1 with chromatin in cis is fundamentally different from that in trans. Our molecular data agree well with the differential phenotypic effect on bwD trans-inactivation of various genes known to be involved in histone modification and cis gene silencing.
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Pindyurin AV, Boldyreva LV, Shloma VV, Kolesnikova TD, Pokholkova GV, Andreyeva EN, Kozhevnikova EN, Ivanoschuk IG, Zarutskaya EA, Demakov SA, Gorchakov AA, Belyaeva ES, Zhimulev IF. Interaction between theDrosophilaheterochromatin proteins SUUR and HP1. J Cell Sci 2008; 121:1693-703. [DOI: 10.1242/jcs.018655] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
SUUR (Suppressor of Under-Replication) protein is responsible for late replication and, as a consequence, for DNA underreplication of intercalary and pericentric heterochromatin in Drosophila melanogaster polytene chromosomes. However, the mechanism by which SUUR slows down the replication process is not clear. To identify possible partners for SUUR we performed a yeast two-hybrid screen using full-length SUUR as bait. This identified HP1, the well-studied heterochromatin protein, as a strong SUUR interactor. Furthermore, we have determined that the central region of SUUR is necessary and sufficient for interaction with the C-terminal part of HP1, which contains the hinge and chromoshadow domains. In addition, recruitment of SUUR to ectopic HP1 sites on chromosomes provides evidence for their association in vivo. Indeed, we found that the distributions of SUUR and HP1 on polytene chromosomes are interdependent: both absence and overexpression of HP1 prevent SUUR from chromosomal binding, whereas SUUR overexpression causes redistribution of HP1 to numerous sites occupied by SUUR. Finally, HP1 binds to intercalary heterochromatin when histone methyltransferase activity of SU(VAR)3-9 is increased. We propose that interaction with HP1 is crucial for the association of SUUR with chromatin.
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Affiliation(s)
- Alexey V. Pindyurin
- Institute of Cytology and Genetics of Siberian Division, Russian Academy of Sciences, Novosibirsk 630090, Russia
| | - Lidiya V. Boldyreva
- Institute of Cytology and Genetics of Siberian Division, Russian Academy of Sciences, Novosibirsk 630090, Russia
| | - Victor V. Shloma
- Institute of Cytology and Genetics of Siberian Division, Russian Academy of Sciences, Novosibirsk 630090, Russia
| | - Tatiana D. Kolesnikova
- Institute of Cytology and Genetics of Siberian Division, Russian Academy of Sciences, Novosibirsk 630090, Russia
- Department of Cytology and Genetics, Novosibirsk State University, Novosibirsk 630090, Russia
| | - Galina V. Pokholkova
- Institute of Cytology and Genetics of Siberian Division, Russian Academy of Sciences, Novosibirsk 630090, Russia
| | - Evgeniya N. Andreyeva
- Institute of Cytology and Genetics of Siberian Division, Russian Academy of Sciences, Novosibirsk 630090, Russia
| | - Elena N. Kozhevnikova
- Institute of Cytology and Genetics of Siberian Division, Russian Academy of Sciences, Novosibirsk 630090, Russia
| | - Igor G. Ivanoschuk
- Institute of Cytology and Genetics of Siberian Division, Russian Academy of Sciences, Novosibirsk 630090, Russia
| | - Ekaterina A. Zarutskaya
- Institute of Cytology and Genetics of Siberian Division, Russian Academy of Sciences, Novosibirsk 630090, Russia
| | - Sergey A. Demakov
- Institute of Cytology and Genetics of Siberian Division, Russian Academy of Sciences, Novosibirsk 630090, Russia
| | - Andrey A. Gorchakov
- Institute of Cytology and Genetics of Siberian Division, Russian Academy of Sciences, Novosibirsk 630090, Russia
| | - Elena S. Belyaeva
- Institute of Cytology and Genetics of Siberian Division, Russian Academy of Sciences, Novosibirsk 630090, Russia
| | - Igor F. Zhimulev
- Institute of Cytology and Genetics of Siberian Division, Russian Academy of Sciences, Novosibirsk 630090, Russia
- Department of Cytology and Genetics, Novosibirsk State University, Novosibirsk 630090, Russia
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Spierer A, Begeot F, Spierer P, Delattre M. SU(VAR)3-7 links heterochromatin and dosage compensation in Drosophila. PLoS Genet 2008; 4:e1000066. [PMID: 18451980 PMCID: PMC2320979 DOI: 10.1371/journal.pgen.1000066] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2007] [Accepted: 04/04/2008] [Indexed: 01/03/2023] Open
Abstract
In Drosophila, dosage compensation augments X chromosome-linked transcription in males relative to females. This process is achieved by the Dosage Compensation Complex (DCC), which associates specifically with the male X chromosome. We previously found that the morphology of this chromosome is sensitive to the amounts of the heterochromatin-associated protein SU(VAR)3-7. In this study, we examine the impact of change in levels of SU(VAR)3-7 on dosage compensation. We first demonstrate that the DCC makes the X chromosome a preferential target for heterochromatic markers. In addition, reduced or increased amounts of SU(VAR)3-7 result in redistribution of the DCC proteins MSL1 and MSL2, and of Histone 4 acetylation of lysine 16, indicating that a wild-type dose of SU(VAR)3-7 is required for X-restricted DCC targeting. SU(VAR)3-7 is also involved in the dosage compensated expression of the X-linked white gene. Finally, we show that absence of maternally provided SU(VAR)3-7 renders dosage compensation toxic in males, and that global amounts of heterochromatin affect viability of ectopic MSL2-expressing females. Taken together, these results bring to light a link between heterochromatin and dosage compensation. In Drosophila, females have two X chromosomes and males only one. The difference in the dose of X-associated genes is compensated by male-specific protein machinery, the Dosage Compensation Complex (DCC), which augments the activity of genes of the single male X. We report that the specific targeting of the DCC on the male X chromosome depends critically on the correct dose of the SU(VAR)3-7 protein. This protein was previously known to associate with condensed and silenced regions of the chromosomes called heterochromatin by contrast with the active form of chromatin called euchromatin. Loss of SU(VAR)3-7 in males causes displacement of the DCC to heterochromatin and bloating of the X chromosome. In contrast, excess of SU(VAR)3-7 leads to a delocalization of the DCC to other chromosomes and to massive shrinking of the X chromosome. We show that SU(VAR)3-7 is involved in the dosage compensated expression of the X-linked white gene and in the viability of dosage compensated flies. Altogether, these results bring to light a link between silencing mechanisms of heterochromatin and mechanisms controlling the balance of sex-chromosome activity (dosage compensation). This opens new perspectives on how complexes that control the global chromosome organisation impact the fine tuning of gene expression.
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Affiliation(s)
- Anne Spierer
- NCCR “Frontiers in Genetics”, Department of Zoology and Animal Biology, University of Geneva, Geneva, Switzerland
| | - Flora Begeot
- NCCR “Frontiers in Genetics”, Department of Zoology and Animal Biology, University of Geneva, Geneva, Switzerland
| | - Pierre Spierer
- NCCR “Frontiers in Genetics”, Department of Zoology and Animal Biology, University of Geneva, Geneva, Switzerland
- * E-mail:
| | - Marion Delattre
- NCCR “Frontiers in Genetics”, Department of Zoology and Animal Biology, University of Geneva, Geneva, Switzerland
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Girton JR, Johansen KM. Chromatin structure and the regulation of gene expression: the lessons of PEV in Drosophila. ADVANCES IN GENETICS 2008; 61:1-43. [PMID: 18282501 DOI: 10.1016/s0065-2660(07)00001-6] [Citation(s) in RCA: 108] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Position-effect variegation (PEV) was discovered in 1930 in a study of X-ray-induced chromosomal rearrangements. Rearrangements that place euchromatic genes adjacent to a region of centromeric heterochromatin give a variegated phenotype that results from the inactivation of genes by heterochromatin spreading from the breakpoint. PEV can also result from P element insertions that place euchromatic genes into heterochromatic regions and rearrangements that position euchromatic chromosomal regions into heterochromatic nuclear compartments. More than 75 years of studies of PEV have revealed that PEV is a complex phenomenon that results from fundamental differences in the structure and function of heterochromatin and euchromatin with respect to gene expression. Molecular analysis of PEV began with the discovery that PEV phenotypes are altered by suppressor and enhancer mutations of a large number of modifier genes whose products are structural components of heterochromatin, enzymes that modify heterochromatic proteins, or are nuclear structural components. Analysis of these gene products has led to our current understanding that formation of heterochromatin involves specific modifications of histones leading to the binding of particular sets of heterochromatic proteins, and that this process may be the mechanism for repressing gene expression in PEV. Other modifier genes produce products whose function is part of an active mechanism of generation of euchromatin that resists heterochromatization. Current studies of PEV are focusing on defining the complex patterns of modifier gene activity and the sequence of events that leads to the dynamic interplay between heterochromatin and euchromatin.
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Affiliation(s)
- Jack R Girton
- Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, Ames, Iowa 50011, USA
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34
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Josse T, Teysset L, Todeschini AL, Sidor CM, Anxolabéhère D, Ronsseray S. Telomeric trans-silencing: an epigenetic repression combining RNA silencing and heterochromatin formation. PLoS Genet 2007; 3:1633-43. [PMID: 17941712 PMCID: PMC1976332 DOI: 10.1371/journal.pgen.0030158] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2007] [Accepted: 07/31/2007] [Indexed: 12/02/2022] Open
Abstract
The study of P-element repression in Drosophila melanogaster led to the discovery of the telomeric Trans-Silencing Effect (TSE), a repression mechanism by which a transposon or a transgene inserted in subtelomeric heterochromatin (Telomeric Associated Sequence or TAS) has the capacity to repress in trans in the female germline, a homologous transposon, or transgene located in euchromatin. TSE shows variegation among egg chambers in ovaries when silencing is incomplete. Here, we report that TSE displays an epigenetic transmission through meiosis, which involves an extrachromosomal maternally transmitted factor. We show that this silencing is highly sensitive to mutations affecting both heterochromatin formation (Su(var)205 encoding Heterochromatin Protein 1 and Su(var)3–7) and the repeat-associated small interfering RNA (or rasiRNA) silencing pathway (aubergine, homeless, armitage, and piwi). In contrast, TSE is not sensitive to mutations affecting r2d2, which is involved in the small interfering RNA (or siRNA) silencing pathway, nor is it sensitive to a mutation in loquacious, which is involved in the micro RNA (or miRNA) silencing pathway. These results, taken together with the recent discovery of TAS homologous small RNAs associated to PIWI proteins, support the proposition that TSE involves a repeat-associated small interfering RNA pathway linked to heterochromatin formation, which was co-opted by the P element to establish repression of its own transposition after its recent invasion of the D. melanogaster genome. Therefore, the study of TSE provides insight into the genetic properties of a germline-specific small RNA silencing pathway. The genome of the fruitfly was invaded in the last century by a mobile DNA element called the P element. After a transient period of genetic disorders due to P mobility, the P element established a repressive state for its transposition. We have shown that a major component of this repression comes from P copies inserted close to telomeres, the ends of linear chromosomes. One or two P copies inserted in subtelomeric heterochromatin (the DNA region highly compacted by protein complexes) can stabilize around 80 P copies. This finding allowed the discovery of a more general phenomenon called the “Trans-silencing effect” in which a transgene inserted in this subtelomeric heterochromatin represses, in the female germline, a homologous transgene, irrespective of the genetic location of the latter. We show that Trans-silencing requires not only the chromosomal copy of the telomeric silencer, but also a maternally transmitted factor whose influence can persist over generations. We have found that this epigenetic silencing is sensitive to mutations in genes involved in heterochromatin formation and in a recently discovered silencing pathway based on small RNAs. Trans-silencing thus provides a tool for mechanistic analysis of gene repression on the basis of chromatin changes combined with small RNA pathways in the germline.
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Affiliation(s)
- Thibaut Josse
- Laboratoire Dynamique du Génome et Evolution, Institut Jacques Monod, Paris, France
- CNRS, UMR7592, Paris, France
- Université Paris 6, Paris, France
- Université Paris 7, Paris, France
| | - Laure Teysset
- Laboratoire Dynamique du Génome et Evolution, Institut Jacques Monod, Paris, France
- CNRS, UMR7592, Paris, France
- Université Paris 6, Paris, France
- Université Paris 7, Paris, France
| | - Anne-Laure Todeschini
- Laboratoire Dynamique du Génome et Evolution, Institut Jacques Monod, Paris, France
- CNRS, UMR7592, Paris, France
- Université Paris 6, Paris, France
- Université Paris 7, Paris, France
| | - Clara M Sidor
- Laboratoire Dynamique du Génome et Evolution, Institut Jacques Monod, Paris, France
- CNRS, UMR7592, Paris, France
- Université Paris 6, Paris, France
- Université Paris 7, Paris, France
| | - Dominique Anxolabéhère
- Laboratoire Dynamique du Génome et Evolution, Institut Jacques Monod, Paris, France
- CNRS, UMR7592, Paris, France
- Université Paris 6, Paris, France
- Université Paris 7, Paris, France
| | - Stéphane Ronsseray
- Laboratoire Dynamique du Génome et Evolution, Institut Jacques Monod, Paris, France
- CNRS, UMR7592, Paris, France
- Université Paris 6, Paris, France
- Université Paris 7, Paris, France
- * To whom correspondence should be addressed. E-mail:
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Andreyeva EN, Kolesnikova TD, Demakova OV, Mendez-Lago M, Pokholkova GV, Belyaeva ES, Rossi F, Dimitri P, Villasante A, Zhimulev IF. High-resolution analysis of Drosophila heterochromatin organization using SuUR Su(var)3-9 double mutants. Proc Natl Acad Sci U S A 2007; 104:12819-24. [PMID: 17640911 PMCID: PMC1937550 DOI: 10.1073/pnas.0704690104] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The structural and functional analyses of heterochromatin are essential to understanding how heterochromatic genes are regulated and how centromeric chromatin is formed. Because the repetitive nature of heterochromatin hampers its genome analysis, new approaches need to be developed. Here, we describe how, in double mutants for Su(var)3-9 and SuUR genes encoding two structural proteins of heterochromatin, new banded heterochromatic segments appear in all polytene chromosomes due to the strong suppression of under-replication in pericentric regions. FISH on salivary gland polytene chromosomes from these double mutant larvae allows high resolution of heterochromatin mapping. In addition, immunostaining experiments with a set of antibodies against euchromatic and heterochromatic proteins reveal their unusual combinations in the newly appeared segments: binding patterns for HP1 and HP2 are coincident, but both are distinct from H3diMetK9 and H4triMetK20. In several regions, partial overlapping staining is observed for the proteins characteristic of active chromatin RNA Pol II, H3triMetK4, Z4, and JIL1, the boundary protein BEAF, and the heterochromatin-enriched proteins HP1, HP2, and SU(VAR)3-7. The exact cytological position of the centromere of chromosome 3 was visualized on salivary gland polytene chromosomes by using the centromeric dodeca satellite and the centromeric protein CID. This region is enriched in H3diMetK9 and H4triMetK20 but is devoid of other proteins analyzed.
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Affiliation(s)
- Eugenia N. Andreyeva
- *Laboratory of Molecular Cytogenetics, Institute of Cytology and Genetics, Siberian Branch of Russian Academy of Sciences, Novosibirsk 630090, Russia
| | - Tatyana D. Kolesnikova
- *Laboratory of Molecular Cytogenetics, Institute of Cytology and Genetics, Siberian Branch of Russian Academy of Sciences, Novosibirsk 630090, Russia
| | - Olga V. Demakova
- *Laboratory of Molecular Cytogenetics, Institute of Cytology and Genetics, Siberian Branch of Russian Academy of Sciences, Novosibirsk 630090, Russia
| | - Maria Mendez-Lago
- Centro de Biología Molecular “Severo Ochoa,” Universidad Autonóma de Madrid, Cantoblanco, 28049 Madrid, Spain; and
| | - Galina V. Pokholkova
- *Laboratory of Molecular Cytogenetics, Institute of Cytology and Genetics, Siberian Branch of Russian Academy of Sciences, Novosibirsk 630090, Russia
| | - Elena S. Belyaeva
- *Laboratory of Molecular Cytogenetics, Institute of Cytology and Genetics, Siberian Branch of Russian Academy of Sciences, Novosibirsk 630090, Russia
| | - Fabrizio Rossi
- Istituto Pasteur–Fondazione Cenci Bolognetti and Dipartimento di Genetica e Biologia Molecolare, Università “La Sapienza,” Via dei Sardi, 70, 00185 Rome, Italy
| | - Patrizio Dimitri
- Istituto Pasteur–Fondazione Cenci Bolognetti and Dipartimento di Genetica e Biologia Molecolare, Università “La Sapienza,” Via dei Sardi, 70, 00185 Rome, Italy
| | - Alfredo Villasante
- Centro de Biología Molecular “Severo Ochoa,” Universidad Autonóma de Madrid, Cantoblanco, 28049 Madrid, Spain; and
| | - Igor F. Zhimulev
- *Laboratory of Molecular Cytogenetics, Institute of Cytology and Genetics, Siberian Branch of Russian Academy of Sciences, Novosibirsk 630090, Russia
- To whom correspondence should be addressed at:
Institute of Cytology and Genetics, Siberian Branch of Russian Academy of Sciences, Lavrentyev Avenue 10, Novosibirsk 630090, Russia. E-mail:
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Greil F, de Wit E, Bussemaker HJ, van Steensel B. HP1 controls genomic targeting of four novel heterochromatin proteins in Drosophila. EMBO J 2007; 26:741-51. [PMID: 17255947 PMCID: PMC1794385 DOI: 10.1038/sj.emboj.7601527] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2006] [Accepted: 11/23/2006] [Indexed: 01/08/2023] Open
Abstract
Heterochromatin is important for the maintenance of genome stability and regulation of gene expression; yet our knowledge of heterochromatin structure and function is incomplete. We identified four novel Drosophila heterochromatin proteins (HPs). Three of these proteins (HP3, HP4 and HP5) interact directly with HP1, whereas HP6 in turn binds to each of these three proteins. Immunofluorescence microscopy and genome-wide mapping of in vivo binding sites shows that all four proteins are components of heterochromatin. Depletion of HP1 causes redistribution of all four proteins, indicating that HP1 is essential for their heterochromatic targeting. Finally, mutants of HP4 and HP5 are dominant suppressors of position effect variegation, demonstrating their importance in heterochromatic gene silencing. These results indicate that HP1 acts as a docking platform for several mediator proteins that contribute to heterochromatin function.
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Affiliation(s)
- Frauke Greil
- Department of Molecular Biology, Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - Elzo de Wit
- Department of Molecular Biology, Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - Harmen J Bussemaker
- Department of Biological Sciences and Center for Computational Biology and Bioinformatics, Columbia University, New York, NY, USA
| | - Bas van Steensel
- Department of Molecular Biology, Netherlands Cancer Institute, Amsterdam, The Netherlands
- Department of Molecular Biology, Netherlands Cancer Institute, Plesmanlaan 121, Amsterdam, 1066 CX Amsterdam, The Netherlands. Tel.: +31 20 512 2040; Fax: +31 20 669 1383; E-mail:
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Haynes KA, Gracheva E, Elgin SCR. A Distinct type of heterochromatin within Drosophila melanogaster chromosome 4. Genetics 2006; 175:1539-42. [PMID: 17194780 PMCID: PMC1840055 DOI: 10.1534/genetics.106.066407] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Studies of transcriptional gene silencing in Drosophila melanogaster suggest that most of chromosome 4 resembles pericentric heterochromatin. However, some modifiers of position-effect variegation, including chromosome 4 dosage and loss of SU(VAR)3-9, have different effects on silencing in pericentric vs. distal arm chromosome 4 heterochromatin, distinguishing these two heterochromatin types.
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Affiliation(s)
- Karmella A Haynes
- Department of Biology, Washington University, St. Louis, Missouri 63130, USA
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38
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Demakova OV, Pokholkova GV, Kolesnikova TD, Demakov SA, Andreyeva EN, Belyaeva ES, Zhimulev IF. The SU(VAR)3-9/HP1 complex differentially regulates the compaction state and degree of underreplication of X chromosome pericentric heterochromatin in Drosophila melanogaster. Genetics 2006; 175:609-20. [PMID: 17151257 PMCID: PMC1800617 DOI: 10.1534/genetics.106.062133] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
In polytene chromosomes of Drosophila melanogaster, regions of pericentric heterochromatin coalesce to form a compact chromocenter and are highly underreplicated. Focusing on study of X chromosome heterochromatin, we demonstrate that loss of either SU(VAR)3-9 histone methyltransferase activity or HP1 protein differentially affects the compaction of different pericentric regions. Using a set of inversions breaking X chromosome heterochromatin in the background of the Su(var)3-9 mutations, we show that distal heterochromatin (blocks h26-h29) is the only one within the chromocenter to form a big "puff"-like structure. The "puffed" heterochromatin has not only unique morphology but also very special protein composition as well: (i) it does not bind proteins specific for active chromatin and should therefore be referred to as a pseudopuff and (ii) it strongly associates with heterochromatin-specific proteins SU(VAR)3-7 and SUUR, despite the fact that HP1 and HP2 are depleted particularly from this polytene structure. The pseudopuff completes replication earlier than when it is compacted as heterochromatin, and underreplication of some DNA sequences within the pseudopuff is strongly suppressed. So, we show that pericentric heterochromatin is heterogeneous in its requirement for SU(VAR)3-9 with respect to the establishment of the condensed state, time of replication, and DNA polytenization.
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Affiliation(s)
- Olga V Demakova
- Laboratory of Molecular Cytogenetics, Institute of Cytology and Genetics, Russian Academy of Sciences, Novosibirsk 630090, Russia
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Abstract
One of the oldest unsolved problems in genetics is the observation that gene silencing can 'spread' along a chromosome. Although spreading has been widely perceived as a process of long-range assembly of heterochromatin proteins, such 'oozing' might not apply in most cases. Rather, long-range silencing seems to be a dynamic process, involving local diffusion of histone-modifying enzymes from source binding sites to low-affinity sites nearby. Discontinuous silencing might reflect looping interactions, whereas the spreading of continuous silencing might be driven by the processive movement of RNA or DNA polymerases. We review the evidence for the spreading of silencing in many contexts and organisms and conclude that multiple mechanisms have evolved that silence genes at a distance.
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Affiliation(s)
- Paul B Talbert
- Howard Hughes Medical Institute, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue North, Seattle, Washington 98109, USA
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40
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Shaffer CD, Cenci G, Thompson B, Stephens GE, Slawson EE, Adu-Wusu K, Gatti M, Elgin SCR. The large isoform of Drosophila melanogaster heterochromatin protein 2 plays a critical role in gene silencing and chromosome structure. Genetics 2006; 174:1189-204. [PMID: 16980400 PMCID: PMC1667101 DOI: 10.1534/genetics.106.057604] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Drosophila melanogaster heterochromatin protein 2 (HP2) interacts with heterochromatin protein 1 (HP1). In polytene chromosomes, HP2 and HP1 colocalize at the chromocenter, telomeres, and the small fourth chromosome. We show here that HP2 is present in the arms as well as the centromeric regions of mitotic chromosomes. We also demonstrate that Su(var)2-HP2 exhibits a dosage-dependent modification of variegation of a yellow reporter transgene, indicating a structural role in heterochromatin formation. We have isolated and characterized 14 new mutations in the Su(var)2-HP2 gene. Using wm4h, many (but not all) mutant alleles show dominant Su(var) activity. Su(var)2-HP2 mutant larvae show a wide variety of mitotic abnormalities, but not the telomere fusion seen in larvae deficient for HP1. The Su(var)2-HP2 gene codes for two isoforms: HP2-L (approximately 365 kDa) and HP2-S (approximately 175 kDa), lacking exons 5 and 6. In general, mutations that affect only the larger isoform result in more pronounced defects than do mutations common to both isoforms. This suggests that an imbalance between large and small isoforms is particularly deleterious. These results indicate a role for HP2 in the structural organization of chromosomes and in heterochromatin-induced gene silencing and show that the larger isoform plays a critical role in these processes.
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41
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Ebert A, Lein S, Schotta G, Reuter G. Histone modification and the control of heterochromatic gene silencing in Drosophila. Chromosome Res 2006; 14:377-92. [PMID: 16821134 DOI: 10.1007/s10577-006-1066-1] [Citation(s) in RCA: 149] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Covalent modifications of histones index structurally and functionally distinct chromatin domains in eukaryotic nuclei. Drosophila with its polytene chromosomes and developed genetics allows detailed cytological as well as functional analysis of epigenetic histone modifications involved in the control of gene expression pattern during development. All H3K9 mono- and dimethylation together with all H3K27 methylation states and H4K20 trimethylation are predominant marks of pericentric heterochromatin. In euchromatin, bands and interbands are differentially indexed. H3K4 and H3K36 methylation together with H3S10 phosphorylation are predominant marks of interband regions whereas in bands different H3K27 and H4K20 methylation states are combined with acetylation of H3K9 and H3K14. Genetic dissection of heterochromatic gene silencing in position-effect variegation (PEV) by Su(var) and E(var) mutations allowed identification and functional analysis of key factors controlling the formation of heterochromatin. SU(VAR)3-9 association with heterochromatic sequences followed by H3K9 methylation initiates the establishment of repressive SU(VAR)3-9/HP1/SU(VAR)3-7 protein complexes. Differential enzymatic activities of novel point mutants demonstrate that the silencing potential of SU(VAR)3-9 is mainly determined by the kinetic properties of the HMTase reaction. In Su(var)3-9ptn a significantly enhanced enzymatic activity results in H3K9 hypermethylation, enhanced gene silencing and extensive chromatin compaction. Mutations in factors controlling active histone modification marks revealed the dynamic balance between euchromatin and heterochromatin. Further analysis and definition of Su(var) and E(var) genes in Drosophila will increase our understanding of the molecular hierarchy of processes controlling higher-order structures in chromatin.
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Affiliation(s)
- Anja Ebert
- Institute of Genetics, Biologicum, Martin Luther University Halle, Weinbergweg 10, D-06120, Halle, Germany
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42
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Jaquet Y, Delattre M, Montoya-Burgos J, Spierer A, Spierer P. Conserved domains control heterochromatin localization and silencing properties of SU(VAR)3–7. Chromosoma 2006; 115:139-50. [PMID: 16463146 DOI: 10.1007/s00412-005-0036-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2005] [Revised: 10/31/2005] [Accepted: 11/07/2005] [Indexed: 11/25/2022]
Abstract
The Drosophila protein SU(VAR)3-7 is essential for fly viability, chromosome structure, and heterochromatin formation. We report that searches in silico and in vitro for homologues of SU(VAR)3-7 were successful within, but not outside, the Drosophila genus. Protein sequence homology between the distant sibling species Drosophila melanogaster and Drosophila virilis is low, except for the general organization of the protein and three conserved motives: seven widely spaced zinc fingers in the N-terminal half and the BESS and BoxA motives in the C-terminal half of the protein. We have undertaken a fine functional dissection of SU(VAR)3-7 in vivo using transgenes encoding truncations of the protein. BESS mediates interaction of SU(VAR)3-7 with itself, and BoxA is required for specific heterochromatin association. Both are necessary for the silencing properties of SU(VAR)3-7. The seven zinc fingers, widely spaced over the N-terminal half of SU(VAR)3-7, are required for binding to polytene chromosomes. One finger is necessary and sufficient to determine the appropriate chromatin association of the C-terminal half of the protein. Conferring a function to each of the conserved motives allows us to better understand the mode of action of SU(VAR)3-7 in triggering heterochromatin formation and subsequent genomic silencing.
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Affiliation(s)
- Yannis Jaquet
- Department of Zoology and Animal Biology, University of Geneva, 30, quai Ernest-Ansermet, 1211, Geneva 4, Switzerland
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43
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Fitzpatrick KA, Sinclair DA, Schulze SR, Syrzycka M, Honda BM. A genetic and molecular profile of third chromosome centric heterochromatin in Drosophila melanogaster. Genome 2005; 48:571-84. [PMID: 16094423 DOI: 10.1139/g05-025] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
In this review, we combine the results of our published and unpublished work with the published results of other laboratories to provide an updated map of the centromeric heterochromatin of chromosome 3 in Drosophila melanogaster. To date, we can identify more than 20 genes (defined DNA sequences with well-characterized functions and (or) defined genetic complementation groups), including at least 16 essential loci. With the ongoing emergence of data from genetic, cytological, and genome sequencing studies, we anticipate continued, substantial progress towards understanding the function, structure, and evolution of centric heterochromatin.
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Affiliation(s)
- K A Fitzpatrick
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, Canada
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Spierer A, Seum C, Delattre M, Spierer P. Loss of the modifiers of variegation Su(var)3-7 or HP1 impacts male X polytene chromosome morphology and dosage compensation. J Cell Sci 2005; 118:5047-57. [PMID: 16234327 DOI: 10.1242/jcs.02623] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Loss of Su(var)3-7 or HP1 suppresses the genomic silencing of position-effect variegation, whereas over-expression enhances it. In addition, loss of Su(var)3-7 results in preferential male lethality. In polytene chromosomes deprived of Su(var)3-7, we observe a specific bloating of the male X chromosome, leading to shortening of the chromosome and to blurring of its banding pattern. In addition, the chromocenter, where heterochromatin from all polytene chromosomes fuses, appears decondensed. The same chromosomal phenotypes are observed as a result of loss of HP1. Mutations of Su(var)3-7 or of Su(var)2-5, the gene encoding HP1, also cause developmental defects, including a spectacular increase in size of the prothoracic gland and its polytene chromosomes. Thus, although structurally very different, the two proteins cooperate closely in chromosome organization and development. Finally, bloating of the male X chromosome in the Su(var)3-7 mutant depends on the presence of a functional dosage compensation complex on this chromosome. This observation reveals a new and intriguing genetic interaction between epigenetic silencing and compensation of dose.
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Affiliation(s)
- Anne Spierer
- Department of Zoology and Animal Biology, University of Geneva, 30 quai Ernest-Ansermet, CH-1211 Geneva 4, Switzerland
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Stephens GE, Slawson EE, Craig CA, Elgin SCR. Interaction of heterochromatin protein 2 with HP1 defines a novel HP1-binding domain. Biochemistry 2005; 44:13394-403. [PMID: 16201764 PMCID: PMC2534139 DOI: 10.1021/bi051006+] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Heterochromatin Protein 2 (HP2) is a nonhistone chromosomal protein from Drosophila melanogaster localized principally in the pericentric heterochromatin, telomeres, and fourth chromosome, all regions associated with HP1. Mutations in HP2 can suppress position effect variegation, indicating a role in gene silencing and heterochromatin formation [Shaffer, C. D. et al. (2002) Proc. Natl. Acad. Sci.U.S.A. 99, 14332-14337]. In vitro coimmunoprecipitation experiments with various peptides from HP2 have identified a single HP1-binding domain. Conserved domains in HP2, including those within the HP1-binding region, have been identified by recovering and sequencing Su(var)2-HP2 from D. willistoni and D. virilis, as well as examining available sequence data from D. pseudoobscura. A PxVxL motif, shown to be an HP1-binding domain in many HP1-interacting proteins, is observed but is not well-conserved in location and sequence and does not mediate HP2 binding to HP1. The sole HP1-binding domain is composed of two conserved regions of 12 and 16 amino acids separated by 19 amino acids. Site-directed mutagenesis within the two conserved regions has shown that the 16 amino acid domain is critical for HP1 binding. This constitutes a novel domain for HP1 interaction, providing a critical link for heterochromatin formation in Drosophila.
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Affiliation(s)
- Gena E Stephens
- Department of Biology, Washington University, CB-1229, St. Louis, Missouri 63130, USA.
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Nikolenko JV, Shidlovskii YV, Lebedeva LA, Krasnov AN, Georgieva SG, Nabirochkina EN. Transcriptional Coactivator SAYP Can Suppress Transcription in Heterochromatin. RUSS J GENET+ 2005. [DOI: 10.1007/s11177-005-0169-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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47
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Lam AL, Pazin DE, Sullivan BA. Control of gene expression and assembly of chromosomal subdomains by chromatin regulators with antagonistic functions. Chromosoma 2005; 114:242-51. [PMID: 16012860 DOI: 10.1007/s00412-005-0001-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2005] [Revised: 04/21/2005] [Accepted: 04/25/2005] [Indexed: 10/25/2022]
Abstract
Epigenetic regulation of higher-order chromatin structure controls gene expression and the assembly of chromosomal domains during cell division, differentiation, and development. The proposed "histone code" integrates a complex system of histone modifications and chromosomal proteins that establish and maintain distinctive types of chromatin, such as euchromatin, heterochromatin, and centromeric (CEN) chromatin. The reversible nature of histone acetylation, phosphorylation, and (most recently discovered) methylation are mechanisms for controlling gene expression and partitioning the genome into functional domains. Many different regions of the genome contain similar epigenetic marks (histone modifications), raising the question as to how they are independently specified and regulated. In this review, we will focus on several recent discoveries in chromatin and chromosome biology: (1) identification of long-elusive histone "de-methylating" enzymes that affect chromatin structure, and (2) assembly and maintenance of chromatin domains, specifically heterochromatin and euchromatin, through a dynamic equilibrium of modifying enzymes, histone modifications, and histone variants identified biochemically and genetically.
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Affiliation(s)
- Ai Leen Lam
- Department of Genetics and Genomics, Boston University School of Medicine, 715 Albany Street, E-645, Boston, MA 02118, USA
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48
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Abstract
Although heterochromatin has been studied for 80 years, its genetic function and molecular organization have remained elusive. In almost all organisms, heterochromatin has been regarded as genetically inactive chromosome regions. However, from genetic and genomic studies in Drosophila melanogaster and other organisms including humans, it is now clear that transcriptionally active domains are present within constitutive heterochromatin. These domains contain essential coding genes whose expression during development ensures the formation of the proper biochemical and morphological phenotypes, together with several gene models defined by genome annotation whose functions still need to be determined.
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Affiliation(s)
- Patrizio Dimitri
- Dipartimento di Genetica e Biologia Molecolare, Università La Sapienza, 70-00185 Roma, Italy.
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49
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Shidlovskii YV, Krasnov AN, Nikolenko JV, Lebedeva LA, Kopantseva M, Ermolaeva MA, Ilyin YV, Nabirochkina EN, Georgiev PG, Georgieva SG. A novel multidomain transcription coactivator SAYP can also repress transcription in heterochromatin. EMBO J 2005; 24:97-107. [PMID: 15616585 PMCID: PMC544920 DOI: 10.1038/sj.emboj.7600508] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2004] [Accepted: 11/15/2004] [Indexed: 11/08/2022] Open
Abstract
Enhancers of yellow (e(y)) is a group of genetically and functionally related genes for proteins involved in transcriptional regulation. The e(y)3 gene of Drosophila considered here encodes a ubiquitous nuclear protein that has homologues in other metazoan species. The protein encoded by e(y)3, named Supporter of Activation of Yellow Protein (SAYP), contains an AT-hook, two PHD fingers, and a novel evolutionarily conserved domain with a transcriptional coactivator function. Mutants expressing a truncated SAYP devoid of the conserved domain die at a midembryonic stage, which suggests a crucial part for SAYP during early development. SAYP binds to numerous sites of transcriptionally active euchromatin on polytene chromosomes and coactivates transcription of euchromatin genes. Unexpectedly, SAYP is also abundant in the heterochromatin regions of the fourth chromosome and in the chromocenter, and represses the transcription of euchromatin genes translocated to heterochromatin; its PHD fingers are essential to heterochromatic silencing. Thus, SAYP plays a dual role in transcription regulation in euchromatic and heterochromatic regions.
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Affiliation(s)
| | - Aleksey N Krasnov
- Institute of Gene Biology, Russian Academy of Sciences, Russia
- Centre for Medical Studies, University of Oslo, Moscow, Russia
| | | | | | | | | | - Yurij V Ilyin
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Russia
| | - Elena N Nabirochkina
- Institute of Gene Biology, Russian Academy of Sciences, Russia
- Centre for Medical Studies, University of Oslo, Moscow, Russia
| | | | - Sofia G Georgieva
- Institute of Gene Biology, Russian Academy of Sciences, Russia
- Centre for Medical Studies, University of Oslo, Moscow, Russia
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Russia
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50
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Delattre M, Spierer A, Jaquet Y, Spierer P. Increased expression ofDrosophilaSu(var)3-7 triggers Su(var)3-9-dependent heterochromatin formation. J Cell Sci 2004; 117:6239-47. [PMID: 15564384 DOI: 10.1242/jcs.01549] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Su(var)3-7 protein is essential for fly viability, and several lines of evidence support its key importance in heterochromatin formation: it binds to pericentric heterochromatin, it potently suppresses variegation and it interacts with HP1. However, the mode of action of Su(var)3-7 is poorly understood. Here we investigate in vivo the consequences of increased Su(var)3-7 expression on fly viability and chromatin structure. A large excess of Su(var)3-7 induces lethality, whereas lower doses permit survival and cause spectacular changes in the morphology of polytene chromosomes in males, and to a lesser extent in females. The male X is always the most affected chromosome: it becomes highly condensed and shortened, and its characteristic banding pattern is modified. In addition, Su(var)3-7 was found over the complete length of all chromosomes. This event coincides with the appearance of heterochromatin markers such as histone H3K9 dimethylation and HP1 at many sites on autosomes and, more strikingly, on the male X chromosome. These two features are strictly dependent on the histone-methyltransferase Su(var)3-9, whereas the generalised localisation of Su(var)3-7 is not. These data provide evidence for a dose-dependent regulatory role of Su(var)3-7 in chromosome morphology and heterochromatin formation. Moreover they show that Su(var)3-7 expression is sufficient to induce Su(var)3-9-dependent ectopic heterochromatinisation and suggest a functional link between Su(var)3-7 and the histone-methyltransferase Su(var)3-9.
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Affiliation(s)
- Marion Delattre
- Department of Zoology and Animal Biology, University of Geneva, 30, quai Ernest-Ansermet, 1211, Geneva 4, Switzerland
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