1
|
Zhang H, Kapitonova E, Orrego A, Spanos C, Strachan J, Bayne EH. Fission yeast Caprin protein is required for efficient heterochromatin establishment. PLoS Genet 2025; 21:e1011620. [PMID: 40063661 PMCID: PMC11918387 DOI: 10.1371/journal.pgen.1011620] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2024] [Revised: 03/18/2025] [Accepted: 02/12/2025] [Indexed: 03/20/2025] Open
Abstract
Heterochromatin is a key feature of eukaryotic genomes that serves important regulatory and structural roles in regions such as centromeres. In fission yeast, maintenance of existing heterochromatic domains relies on positive feedback loops involving histone methylation and non-coding RNAs. However, requirements for de novo establishment of heterochromatin are less well understood. Here, through a cross-based assay we have identified a novel factor influencing the efficiency of heterochromatin establishment. We determine that the previously uncharacterised protein is an ortholog of human Caprin1, an RNA-binding protein linked to stress granule formation. We confirm that the fission yeast ortholog, here named Cpn1, also associates with stress granules, and we uncover evidence of interplay between heterochromatin integrity and ribonucleoprotein (RNP) granule formation, with heterochromatin mutants showing reduced granule formation in the presence of stress, but increased granule formation in the absence of stress. We link this to regulation of non-coding heterochromatic transcripts, since in heterochromatin-deficient cells, Cpn1 can be seen to colocalise with accumulating pericentromeric transcripts, and absence of Cpn1 leads to hyperaccumulation of these RNAs at centromeres. Together, our findings unveil a novel link between RNP homeostasis and heterochromatin assembly, and implicate Cpn1 and associated factors in facilitating efficient heterochromatin establishment by enabling removal of excess transcripts that would otherwise impair assembly processes.
Collapse
Affiliation(s)
- Haidao Zhang
- Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Ekaterina Kapitonova
- Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Adriana Orrego
- Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Christos Spanos
- Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Joanna Strachan
- Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
- Institute of Molecular Plant Sciences, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Elizabeth H. Bayne
- Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| |
Collapse
|
2
|
Takahata S, Taguchi A, Takenaka A, Mori M, Chikashige Y, Tsutsumi C, Hiraoka Y, Murakami Y. The HMG-box module in FACT is critical for suppressing epigenetic variegation of heterochromatin in fission yeast. Genes Cells 2024; 29:567-583. [PMID: 38837646 DOI: 10.1111/gtc.13132] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2024] [Revised: 05/08/2024] [Accepted: 05/14/2024] [Indexed: 06/07/2024]
Abstract
Chromatin condensation state is the key for retrieving genetic information. High-mobility group protein (HMG) proteins exhibit DNA-binding and bending activities, playing an important role in the regulation of chromatin structure. We have shown that nucleosomes tightly packaged into heterochromatin undergo considerable dynamic histone H2A-H2B maintenance via the direct interaction between HP1/Swi6 and facilitate chromatin transcription (FACT), which is composed of the Spt16/Pob3 heterodimer and Nhp6. In this study, we analyzed the role of Nhp6, an HMG box protein, in the FACT at heterochromatin. Pob3 mutant strains showed derepressed heterochromatin-dependent gene silencing, whereas Nhp6 mutant strains did not show significant defects in chromatin regulation or gene expression, suggesting that these two modules play different roles in chromatin regulation. We expressed a protein fusing Nhp6 to the C-terminus of Pob3, which mimics the multicellular FACT component Ssrp1. The chromatin-binding activity of FACT increased with the number of Nhp6 fused to Pob3, and the heterochromatin formation rate was promoted more strongly. Furthermore, we demonstrated that this promotion of heterochromatinization inhibited the heterochromatic variegation caused by epe1+ disruption. Heterochromatic variegation can be observed in a variety of regulatory steps; however, when it is caused by fluctuations in chromatin arrangement, it can be eliminated through the strong recruitment of the FACT complex.
Collapse
Affiliation(s)
- Shinya Takahata
- Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo, Japan
| | - Asahi Taguchi
- Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo, Japan
| | - Ayaka Takenaka
- Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo, Japan
| | - Miyuki Mori
- Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo, Japan
| | - Yuji Chikashige
- Advanced ICT Research Institute, National Institute of Information and Communications Technology, Kobe, Japan
| | - Chihiro Tsutsumi
- Advanced ICT Research Institute, National Institute of Information and Communications Technology, Kobe, Japan
| | - Yasushi Hiraoka
- Graduate School of Frontier Biosciences, Osaka University, Suita, Japan
| | - Yota Murakami
- Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo, Japan
| |
Collapse
|
3
|
Opposing Roles of FACT for Euchromatin and Heterochromatin in Yeast. Biomolecules 2023; 13:biom13020377. [PMID: 36830746 PMCID: PMC9953268 DOI: 10.3390/biom13020377] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Revised: 02/14/2023] [Accepted: 02/15/2023] [Indexed: 02/19/2023] Open
Abstract
DNA is stored in the nucleus of a cell in a folded state; however, only the necessary genetic information is extracted from the required group of genes. The key to extracting genetic information is chromatin ambivalence. Depending on the chromosomal region, chromatin is characterized into low-density "euchromatin" and high-density "heterochromatin", with various factors being involved in its regulation. Here, we focus on chromatin regulation and gene expression by the yeast FACT complex, which functions in both euchromatin and heterochromatin. FACT is known as a histone H2A/H2B chaperone and was initially reported as an elongation factor associated with RNA polymerase II. In budding yeast, FACT activates promoter chromatin by interacting with the transcriptional activators SBF/MBF via the regulation of G1/S cell cycle genes. In fission yeast, FACT plays an important role in the formation of higher-order chromatin structures and transcriptional repression by binding to Swi6, an HP1 family protein, at heterochromatin. This FACT property, which refers to the alternate chromatin-regulation depending on the binding partner, is an interesting phenomenon. Further analysis of nucleosome regulation within heterochromatin is expected in future studies.
Collapse
|
4
|
Ipsaro JJ, Joshua‐Tor L. Developmental roles and molecular mechanisms of Asterix/GTSF1. WIRES RNA 2022; 13:e1716. [PMID: 35108755 PMCID: PMC9539491 DOI: 10.1002/wrna.1716] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 11/29/2021] [Accepted: 11/30/2021] [Indexed: 01/07/2023]
Abstract
Maintenance of germline genomic integrity is critical for the survival of animal species. Consequently, many cellular and molecular processes have evolved to ensure genetic stability during the production of gametes. Here, we describe the discovery, characterization, and emerging molecular mechanisms of the protein Asterix/Gametocyte‐specific factor 1 (GTSF1), an essential gametogenesis factor that is conserved from insects to humans. Beyond its broad importance for healthy germline development, Asterix/GTSF1 has more specific functions in the Piwi‐interacting RNA (piRNA)–RNA interference pathway. There, it contributes to the repression of otherwise deleterious transposons, helping to ensure faithful transmission of genetic information to the next generation. This article is categorized under:Regulatory RNAs/RNAi/Riboswitches > RNAi: Mechanisms of Action Regulatory RNAs/RNAi/Riboswitches > Regulatory RNAs RNA Interactions with Proteins and Other Molecules > RNA‐Protein Complexes RNA Interactions with Proteins and Other Molecules > Protein‐RNA Interactions: Functional Implications
Collapse
Affiliation(s)
- Jonathan J. Ipsaro
- Howard Hughes Medical Institute W.M. Keck Structural Biology Laboratory, Cold Spring Harbor Laboratory Cold Spring Harbor New York USA
| | - Leemor Joshua‐Tor
- Howard Hughes Medical Institute W.M. Keck Structural Biology Laboratory, Cold Spring Harbor Laboratory Cold Spring Harbor New York USA
| |
Collapse
|
5
|
Paramecium Polycomb repressive complex 2 physically interacts with the small RNA-binding PIWI protein to repress transposable elements. Dev Cell 2022; 57:1037-1052.e8. [DOI: 10.1016/j.devcel.2022.03.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Revised: 02/10/2022] [Accepted: 03/21/2022] [Indexed: 12/30/2022]
|
6
|
Breakers and amplifiers in chromatin circuitry: acetylation and ubiquitination control the heterochromatin machinery. Curr Opin Struct Biol 2021; 71:156-163. [PMID: 34303934 PMCID: PMC8667873 DOI: 10.1016/j.sbi.2021.06.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Revised: 06/06/2021] [Accepted: 06/13/2021] [Indexed: 11/30/2022]
Abstract
Eukaryotic genomes are segregated into active euchromatic and repressed heterochromatic compartments. Gene regulatory networks, chromosomal structures, and genome integrity rely on the timely and locus-specific establishment of active and silent states to protect the genome and provide the basis for cell division and specification of cellular identity. Here, we focus on the mechanisms and molecular machinery that establish heterochromatin in Schizosaccharomyces pombe and compare it with Saccharomyces cerevisiae and the mammalian polycomb system. We present recent structural and mechanistic evidence, which suggests that histone acetylation protects active transcription by disrupting the positive feedback loops used by the heterochromatin machinery and that H2A and H3 monoubiquitination actively drives heterochromatin, whereas H2B monoubiquitination mobilizes the defenses to quench heterochromatin. Heterochromatin-associated complexes are attracted and repelled by histone marks. Acetylation of specific lysine residues protects euchromatin from silencing. Methylation of histone H3 lysine 9 and 27 amplifies heterochromatin. Nucleosome ubiquitination licences and enforces feedback loops.
Collapse
|
7
|
Taglini F, Chapman E, van Nues R, Theron E, Bayne EH. Mkt1 is required for RNAi-mediated silencing and establishment of heterochromatin in fission yeast. Nucleic Acids Res 2020; 48:1239-1253. [PMID: 31822915 PMCID: PMC7026591 DOI: 10.1093/nar/gkz1157] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Revised: 11/12/2019] [Accepted: 11/28/2019] [Indexed: 01/04/2023] Open
Abstract
Constitutive domains of repressive heterochromatin are maintained within the fission yeast genome through self-reinforcing mechanisms involving histone methylation and small RNAs. Non-coding RNAs generated from heterochromatic regions are processed into small RNAs by the RNA interference pathway, and are subject to silencing through both transcriptional and post-transcriptional mechanisms. While the pathways involved in maintenance of the repressive heterochromatin state are reasonably well understood, less is known about the requirements for its establishment. Here, we describe a novel role for the post-transcriptional regulatory factor Mkt1 in establishment of heterochromatin at pericentromeres in fission yeast. Loss of Mkt1 does not affect maintenance of existing heterochromatin, but does affect its recovery following depletion, as well as de novo establishment of heterochromatin on a mini-chromosome. Pathway dissection revealed that Mkt1 is required for RNAi-mediated post-transcriptional silencing, downstream of small RNA production. Mkt1 physically associates with pericentromeric transcripts, and is additionally required for maintenance of silencing and heterochromatin at centromeres when transcriptional silencing is impaired. Our findings provide new insight into the mechanism of RNAi-mediated post-transcriptional silencing in fission yeast, and unveil an important role for post-transcriptional silencing in establishment of heterochromatin that is dispensable when full transcriptional silencing is imposed.
Collapse
Affiliation(s)
- Francesca Taglini
- Institute of Cell Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh, UK
| | - Elliott Chapman
- Institute of Cell Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh, UK
| | - Rob van Nues
- Institute of Cell Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh, UK
| | - Emmanuelle Theron
- Institute of Cell Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh, UK
| | - Elizabeth H Bayne
- Institute of Cell Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh, UK
| |
Collapse
|
8
|
Oya E, Nakagawa R, Yoshimura Y, Tanaka M, Nishibuchi G, Machida S, Shirai A, Ekwall K, Kurumizaka H, Tagami H, Nakayama J. H3K14 ubiquitylation promotes H3K9 methylation for heterochromatin assembly. EMBO Rep 2019; 20:e48111. [PMID: 31468675 PMCID: PMC6776926 DOI: 10.15252/embr.201948111] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2019] [Revised: 08/07/2019] [Accepted: 08/09/2019] [Indexed: 12/28/2022] Open
Abstract
The methylation of histone H3 at lysine 9 (H3K9me), performed by the methyltransferase Clr4/SUV39H, is a key event in heterochromatin assembly. In fission yeast, Clr4, together with the ubiquitin E3 ligase Cul4, forms the Clr4 methyltransferase complex (CLRC), whose physiological targets and biological role are currently unclear. Here, we show that CLRC-dependent H3 ubiquitylation regulates Clr4's methyltransferase activity. Affinity-purified CLRC ubiquitylates histone H3, and mass spectrometric and mutation analyses reveal that H3 lysine 14 (H3K14) is the preferred target of the complex. Chromatin immunoprecipitation analysis shows that H3K14 ubiquitylation (H3K14ub) is closely associated with H3K9me-enriched chromatin. Notably, the CLRC-mediated H3 ubiquitylation promotes H3K9me by Clr4, suggesting that H3 ubiquitylation is intimately linked to the establishment and/or maintenance of H3K9me. These findings demonstrate a cross-talk mechanism between histone ubiquitylation and methylation that is involved in heterochromatin assembly.
Collapse
Affiliation(s)
- Eriko Oya
- Graduate School of Natural SciencesNagoya City UniversityNagoyaJapan
- Department of Biosciences and NutritionKarolinska InstitutetHuddingeSweden
- Present address:
Faculty of Science and EngineeringChuo UniversityBunkyo‐ku, TokyoJapan
| | - Reiko Nakagawa
- Laboratory for PhyloinformaticsRIKEN Center for Biosystems Dynamics ResearchKobeJapan
| | - Yuriko Yoshimura
- Division of Chromatin RegulationNational Institute for Basic BiologyOkazakiJapan
| | - Mayo Tanaka
- Division of Chromatin RegulationNational Institute for Basic BiologyOkazakiJapan
| | - Gohei Nishibuchi
- Graduate School of Natural SciencesNagoya City UniversityNagoyaJapan
- Present address:
Graduate School of ScienceOsaka UniversityToyonakaJapan
| | - Shinichi Machida
- Laboratory of Structural BiologyGraduate School of Advanced Science and EngineeringWaseda UniversityShinjuku‐ku, TokyoJapan
- Present address:
Institute of Human GeneticsCNRS UMR 9002MontpellierFrance
| | | | - Karl Ekwall
- Department of Biosciences and NutritionKarolinska InstitutetHuddingeSweden
| | - Hitoshi Kurumizaka
- Laboratory of Structural BiologyGraduate School of Advanced Science and EngineeringWaseda UniversityShinjuku‐ku, TokyoJapan
- Laboratory of Chromatin Structure and FunctionInstitute for Quantitative BiosciencesThe University of TokyoBunkyo‐ku, TokyoJapan
| | - Hideaki Tagami
- Graduate School of Natural SciencesNagoya City UniversityNagoyaJapan
| | - Jun‐ichi Nakayama
- Graduate School of Natural SciencesNagoya City UniversityNagoyaJapan
- Division of Chromatin RegulationNational Institute for Basic BiologyOkazakiJapan
- Department of Basic BiologySchool of Life ScienceThe Graduate University for Advanced Studies (SOKENDAI)OkazakiJapan
| |
Collapse
|
9
|
Chen J, Kuhn LA. Deciphering the three-domain architecture in schlafens and the structures and roles of human schlafen12 and serpinB12 in transcriptional regulation. J Mol Graph Model 2019; 90:59-76. [PMID: 31026779 PMCID: PMC6657700 DOI: 10.1016/j.jmgm.2019.04.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2018] [Revised: 04/03/2019] [Accepted: 04/05/2019] [Indexed: 12/22/2022]
Abstract
Schlafen proteins are important in cell differentiation and defense against viruses, and yet this family of vertebrate proteins is just beginning to be understood at the molecular level. Here, the three-dimensional architecture and molecular interfaces of human schlafen12 (hSLFN12), which promotes intestinal stem cell differentiation, are analyzed by sequence conservation and structural modeling in light of the functions of its homologs and binding partners. Our analysis shows that the schlafen or divergent AAA ATPase domain described in the N-terminal region of schlafens in databases and the literature is a misannotation. This N-terminal region is conclusively an AlbA_2 DNA/RNA binding domain, forming the conserved core of schlafens and their sequence homologs from bacteria through mammals. Group III schlafens additionally contain a AAA NTPase domain in their C-terminal helicase region. In hSLFN12, we have uncovered a domain matching rho GTPases, which directly follows the AlbA_2 domain in all group II-III schlafens. Potential roles for the GTPase-like domain include antiviral activity and cytoskeletal interactions that contribute to nucleocytoplasmic shuttling and cell polarization during differentiation. Based on features conserved with rSlfn13, the AlbA_2 region in hSLFN12 is likely to bind RNA, possibly as a ribonuclease. We hypothesize that RNA binding by hSLFN12 contributes to an RNA-induced transcriptional silencing/E3 ligase complex, given the functions of hSLFN12's partners, SUV39H1, JMJD6, and PDLIM7. hSLFN12's partner hSerpinB12 may contribute to heterochromatin formation, based on its homology to MENT, or directly regulate transcription via its binding to RNA polymerase II. The analysis presented here provides clear architectural and transcriptional regulation hypotheses to guide experimental design for hSLFN12 and the thousands of schlafens that share its motifs.
Collapse
Affiliation(s)
- Jiaxing Chen
- Protein Structural Analysis and Design Lab, Department of Biochemistry and Molecular Biology, Michigan State University, 603 Wilson Road, East Lansing, MI, 48824-1319, USA
| | - Leslie A Kuhn
- Protein Structural Analysis and Design Lab, Department of Biochemistry and Molecular Biology, Michigan State University, 603 Wilson Road, East Lansing, MI, 48824-1319, USA.
| |
Collapse
|
10
|
Almeida MV, Dietz S, Redl S, Karaulanov E, Hildebrandt A, Renz C, Ulrich HD, König J, Butter F, Ketting RF. GTSF-1 is required for formation of a functional RNA-dependent RNA Polymerase complex in Caenorhabditis elegans. EMBO J 2018; 37:embj.201899325. [PMID: 29769402 DOI: 10.15252/embj.201899325] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Revised: 03/22/2018] [Accepted: 03/24/2018] [Indexed: 11/09/2022] Open
Abstract
Argonaute proteins and their associated small RNAs (sRNAs) are evolutionarily conserved regulators of gene expression. Gametocyte-specific factor 1 (Gtsf1) proteins, characterized by two tandem CHHC zinc fingers and an unstructured C-terminal tail, are conserved in animals and have been shown to interact with Piwi clade Argonautes, thereby assisting their activity. We identified the Caenorhabditis elegans Gtsf1 homolog, named it gtsf-1 and characterized it in the context of the sRNA pathways of C. elegans We report that GTSF-1 is not required for Piwi-mediated gene silencing. Instead, gtsf-1 mutants show a striking depletion of 26G-RNAs, a class of endogenous sRNAs, fully phenocopying rrf-3 mutants. We show, both in vivo and in vitro, that GTSF-1 interacts with RRF-3 via its CHHC zinc fingers. Furthermore, we demonstrate that GTSF-1 is required for the assembly of a larger RRF-3 and DCR-1-containing complex (ERIC), thereby allowing for 26G-RNA generation. We propose that GTSF-1 homologs may act to drive the assembly of larger complexes that act in sRNA production and/or in imposing sRNA-mediated silencing activities.
Collapse
Affiliation(s)
| | - Sabrina Dietz
- Quantitative Proteomics Group, Institute of Molecular Biology, Mainz, Germany
| | - Stefan Redl
- Biology of Non-coding RNA Group, Institute of Molecular Biology, Mainz, Germany
| | - Emil Karaulanov
- Bioinformatics Core Facility, Institute of Molecular Biology, Mainz, Germany
| | - Andrea Hildebrandt
- Genomic Views of Splicing Regulation Group, Institute of Molecular Biology, Mainz, Germany
| | - Christian Renz
- Maintenance of Genome Stability Group, Institute of Molecular Biology, Mainz, Germany
| | - Helle D Ulrich
- Maintenance of Genome Stability Group, Institute of Molecular Biology, Mainz, Germany
| | - Julian König
- Genomic Views of Splicing Regulation Group, Institute of Molecular Biology, Mainz, Germany
| | - Falk Butter
- Quantitative Proteomics Group, Institute of Molecular Biology, Mainz, Germany
| | - René F Ketting
- Biology of Non-coding RNA Group, Institute of Molecular Biology, Mainz, Germany
| |
Collapse
|
11
|
Rodda LB, Lu E, Bennett ML, Sokol CL, Wang X, Luther SA, Barres BA, Luster AD, Ye CJ, Cyster JG. Single-Cell RNA Sequencing of Lymph Node Stromal Cells Reveals Niche-Associated Heterogeneity. Immunity 2018; 48:1014-1028.e6. [PMID: 29752062 PMCID: PMC5971117 DOI: 10.1016/j.immuni.2018.04.006] [Citation(s) in RCA: 311] [Impact Index Per Article: 44.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Revised: 11/23/2017] [Accepted: 04/02/2018] [Indexed: 01/06/2023]
Abstract
Stromal cells (SCs) establish the compartmentalization of lymphoid tissues critical to the immune response. However, the full diversity of lymph node (LN) SCs remains undefined. Using droplet-based single-cell RNA sequencing, we identified nine peripheral LN non-endothelial SC clusters. Included are the established subsets, Ccl19hi T-zone reticular cells (TRCs), marginal reticular cells, follicular dendritic cells (FDCs), and perivascular cells. We also identified Ccl19lo TRCs, likely including cholesterol-25-hydroxylase+ cells located at the T-zone perimeter, Cxcl9+ TRCs in the T-zone and interfollicular region, CD34+ SCs in the capsule and medullary vessel adventitia, indolethylamine N-methyltransferase+ SCs in the medullary cords, and Nr4a1+ SCs in several niches. These data help define how transcriptionally distinct LN SCs support niche-restricted immune functions and provide evidence that many SCs are in an activated state.
Collapse
Affiliation(s)
- Lauren B Rodda
- Howard Hughes Medical Institute and Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Erick Lu
- Howard Hughes Medical Institute and Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Mariko L Bennett
- Department of Neurobiology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Caroline L Sokol
- Center for Immunology & Inflammatory Diseases, Division of Rheumatology, Allergy & Immunology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Xiaoming Wang
- Department of Immunology, Nanjing Medical University, Nanjing, China
| | - Sanjiv A Luther
- Department of Biochemistry, Center for Immunity and Infection, University of Lausanne, 1066 Epalinges, Switzerland
| | - Ben A Barres
- Department of Neurobiology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Andrew D Luster
- Center for Immunology & Inflammatory Diseases, Division of Rheumatology, Allergy & Immunology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Chun Jimmie Ye
- Institute for Human Genetics, Department of Epidemiology and Biostatistics, Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Jason G Cyster
- Howard Hughes Medical Institute and Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, CA 94143, USA.
| |
Collapse
|
12
|
Shimada Y, Mohn F, Bühler M. The RNA-induced transcriptional silencing complex targets chromatin exclusively via interacting with nascent transcripts. Genes Dev 2016; 30:2571-2580. [PMID: 27941123 PMCID: PMC5204350 DOI: 10.1101/gad.292599.116] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Accepted: 11/21/2016] [Indexed: 01/24/2023]
Abstract
Small RNAs regulate chromatin modification and transcriptional gene silencing across the eukaryotic kingdom. Although these processes have been well studied, fundamental mechanistic aspects remain obscure. Specifically, it is unclear exactly how small RNA-loaded Argonaute protein complexes target chromatin to mediate silencing. Here, using fission yeast, we demonstrate that transcription of the target locus is essential for RNA-directed formation of heterochromatin. However, high transcriptional activity is inhibitory; thus, a transcriptional window exists that is optimal for silencing. We further found that pre-mRNA splicing is compatible with RNA-directed heterochromatin formation. However, the kinetics of pre-mRNA processing is critical. Introns close to the 5' end of a transcript that are rapidly spliced result in a bistable response whereby the target either remains euchromatic or becomes fully silenced. Together, our results discount siRNA-DNA base pairing in RNA-mediated heterochromatin formation, and the mechanistic insights further reveal guiding paradigms for the design of small RNA-directed chromatin silencing studies in multicellular organisms.
Collapse
Affiliation(s)
- Yukiko Shimada
- Friedrich Miescher Institute for Biomedical Research, 4058 Basel, Switzerland.,University of Basel, 4003 Basel, Switzerland
| | - Fabio Mohn
- Friedrich Miescher Institute for Biomedical Research, 4058 Basel, Switzerland.,University of Basel, 4003 Basel, Switzerland
| | - Marc Bühler
- Friedrich Miescher Institute for Biomedical Research, 4058 Basel, Switzerland.,University of Basel, 4003 Basel, Switzerland
| |
Collapse
|
13
|
Bayne EH, Bijos DA, White SA, de Lima Alves F, Rappsilber J, Allshire RC. A systematic genetic screen identifies new factors influencing centromeric heterochromatin integrity in fission yeast. Genome Biol 2015; 15:481. [PMID: 25274039 PMCID: PMC4210515 DOI: 10.1186/s13059-014-0481-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2014] [Indexed: 12/20/2022] Open
Abstract
Background Heterochromatin plays important roles in the regulation and stability of eukaryotic genomes. Both heterochromatin components and pathways that promote heterochromatin assembly, including RNA interference, RNAi, are broadly conserved between the fission yeast Schizosaccharomyces pombe and humans. As a result, fission yeast has emerged as an important model system for dissecting mechanisms governing heterochromatin integrity. Thus far, over 50 proteins have been found to contribute to heterochromatin assembly at fission yeast centromeres. However, previous studies have not been exhaustive, and it is therefore likely that further factors remain to be identified. Results To gain a more complete understanding of heterochromatin assembly pathways, we have performed a systematic genetic screen for factors required for centromeric heterochromatin integrity. In addition to known RNAi and chromatin modification components, we identified several proteins with previously undescribed roles in heterochromatin regulation. These included both known and newly characterised splicing-associated proteins, which are required for proper processing of centromeric transcripts by the RNAi pathway, and COP9 signalosome components Csn1 and Csn2, whose role in heterochromatin assembly can be explained at least in part by a role in the Ddb1-dependent degradation of the heterochromatin regulator Epe1. Conclusions This work has revealed new factors involved in RNAi-directed heterochromatin assembly in fission yeast. Our findings support and extend previous observations that implicate components of the splicing machinery as a platform for RNAi, and demonstrate a novel role for the COP9 signalosome in heterochromatin regulation. Electronic supplementary material The online version of this article (doi:10.1186/s13059-014-0481-4) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Elizabeth H Bayne
- Institute of Cell Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh EH9 3JR, UK.
| | | | | | | | | | | |
Collapse
|
14
|
Houseley J, Hill CS, Rugg‐Gunn PJ. Annual meeting of the EpiGeneSys Network of Excellence--Advancing epigenetics towards systems biology. Bioessays 2015; 37:592-5. [PMID: 25776341 PMCID: PMC5031200 DOI: 10.1002/bies.201500015] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The third annual meeting of the EpiGeneSys network brought together epigenetics and systems biologists to report on collaborative projects that apply quantitative approaches to understanding complex epigenetic processes. The figure shown represents one meeting highlight, which was the unexpected emergence of genotype versus epigenotype in control of cell state. © 2015 The Authors. Bioessays published by WILEY Periodicals, Inc.
Collapse
Affiliation(s)
- Jon Houseley
- Epigenetics ProgrammeThe Babraham InstituteCambridgeUK
| | - Caroline S. Hill
- Laboratory of Developmental SignallingCancer Research UK London Research InstituteLondonUK
| | | |
Collapse
|
15
|
CRL4-like Clr4 complex in Schizosaccharomyces pombe depends on an exposed surface of Dos1 for heterochromatin silencing. Proc Natl Acad Sci U S A 2014; 111:1795-800. [PMID: 24449894 DOI: 10.1073/pnas.1313096111] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Repressive histone H3 lysine 9 methylation (H3K9me) and its recognition by HP1 proteins are necessary for pericentromeric heterochromatin formation. In Schizosaccharomyces pombe, H3K9me deposition depends on the RNAi pathway. Cryptic loci regulator 4 (Clr4), the only known H3K9 methyltransferase in this organism, is a subunit of the Clr4 methyltransferase complex (CLRC), whose composition is reminiscent of a CRL4 type cullin-RING ubiquitin ligase (CRL) including its cullin Cul4, the RING-box protein Pip1, the DNA damage binding protein 1 homolog Rik1, and the DCAF-like protein delocalization of Swi6 1 (Dos1). Dos2 and Stc1 have been proposed to be part of the complex but do not bear similarity to canonical ubiquitin ligase components. CLRC is an active E3 ligase in vitro, and this activity is necessary for heterochromatin assembly in vivo. The similarity between CLRC and the CRLs suggests that the WD repeat protein Dos1 will act to mediate target recognition and substrate specificity for CLRC. Here, we present a pairwise interaction screen that confirms a CRL4-like subunit arrangement and further identifies Dos2 as a central component of the complex and recruiter of Stc1. We determined the crystal structure of the Dos1 WD repeat domain, revealing an eight-bladed β-propeller fold. Functional mapping of the putative target-binding surface of Dos1 identifies key residues required for heterochromatic silencing, consistent with Dos1's role as the specificity factor for the E3 ubiquitin ligase.
Collapse
|
16
|
Dönertas D, Sienski G, Brennecke J. Drosophila Gtsf1 is an essential component of the Piwi-mediated transcriptional silencing complex. Genes Dev 2013; 27:1693-705. [PMID: 23913922 DOI: 10.1101/gad.221150.113] [Citation(s) in RCA: 103] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The PIWI-interacting RNA (piRNA) pathway is a small RNA silencing system that keeps selfish genetic elements such as transposons under control in animal gonads. Several lines of evidence indicate that nuclear PIWI family proteins guide transcriptional silencing of their targets, yet the composition of the underlying silencing complex is unknown. Here we demonstrate that the double CHHC zinc finger protein gametocyte-specific factor 1 (Gtsf1) is an essential factor for Piwi-mediated transcriptional repression in Drosophila. Cells lacking Gtsf1 contain nuclear Piwi loaded with piRNAs, yet Piwi's silencing capacity is ablated. Gtsf1 interacts directly with a small subpool of nuclear Piwi, and loss of Gtsf1 phenocopies loss of Piwi in terms of deregulation of transposons, loss of H3K9 trimethylation (H3K9me3) marks at euchromatic transposon insertions, and deregulation of genes in proximity to repressed transposons. We propose that only a small fraction of nuclear Piwi is actively engaged in target silencing and that Gtsf1 is an essential component of the underlying Piwi-centered silencing complex.
Collapse
Affiliation(s)
- Derya Dönertas
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences IMBA, 1030 Vienna, Austria
| | | | | |
Collapse
|