1
|
Wong CYY, Tsui HN, Wang Y, Yuen KWY. Argonaute protein CSR-1 restricts localization of holocentromere protein HCP-3, the C. elegans CENP-A homolog. J Cell Sci 2024; 137:jcs261895. [PMID: 39037215 PMCID: PMC11423810 DOI: 10.1242/jcs.261895] [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: 12/17/2023] [Accepted: 07/11/2024] [Indexed: 07/23/2024] Open
Abstract
Chromosome segregation errors caused by centromere malfunction can lead to chromosome instability and aneuploidy. In Caenorhabditis elegans, the Argonaute protein CSR-1 is essential for proper chromosome segregation, although the specific mechanisms are not fully understood. Here, we investigated how CSR-1 regulates centromere and kinetochore function in C. elegans embryos. We found that depletion of CSR-1 results in defects in mitotic progression and chromosome positioning relative to the spindle pole. Knockdown of CSR-1 does not affect mRNA and protein levels of the centromeric histone H3 variant and CENP-A homolog HCP-3 but does increase the localization of HCP-3 and some kinetochore proteins to the mitotic chromosomes. Such elevation of HCP-3 chromatin localization depends on EGO-1, which is an upstream factor in the CSR-1 RNA interference (RNAi) pathway, and PIWI domain activity of CSR-1. Our results suggest that CSR-1 restricts the level of HCP-3 at the holocentromeres, prevents erroneous kinetochore assembly and thereby promotes accurate chromosome segregation. Our work sheds light on the role of CSR-1 in regulating deposition of HCP-3 on chromatin and centromere function in embryos.
Collapse
Affiliation(s)
| | - Hok Ning Tsui
- School of Biological Sciences, The University of Hong Kong, Hong Kong
| | - Yue Wang
- School of Biological Sciences, The University of Hong Kong, Hong Kong
| | - Karen Wing Yee Yuen
- School of Biological Sciences, The University of Hong Kong, Hong Kong
- School of Biological Sciences, University of Southampton, Southampton SO17 1BJ, UK
| |
Collapse
|
2
|
Aguirre S, Pappa S, Serna-Pujol N, Padilla N, Iacobucci S, Nacht AS, Vicent GP, Jordan A, de la Cruz X, Martínez-Balbás MA. PHF2-mediated H3K9me balance orchestrates heterochromatin stability and neural progenitor proliferation. EMBO Rep 2024; 25:3486-3505. [PMID: 38890452 PMCID: PMC11315909 DOI: 10.1038/s44319-024-00178-7] [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: 11/30/2023] [Revised: 05/18/2024] [Accepted: 06/04/2024] [Indexed: 06/20/2024] Open
Abstract
Heterochromatin stability is crucial for progenitor proliferation during early neurogenesis. It relays on the maintenance of local hubs of H3K9me. However, understanding the formation of efficient localized levels of H3K9me remains limited. To address this question, we used neural stem cells to analyze the function of the H3K9me2 demethylase PHF2, which is crucial for progenitor proliferation. Through mass-spectroscopy and genome-wide assays, we show that PHF2 interacts with heterochromatin components and is enriched at pericentromeric heterochromatin (PcH) boundaries where it maintains transcriptional activity. This binding is essential for silencing the satellite repeats, preventing DNA damage and genome instability. PHF2's depletion increases the transcription of heterochromatic repeats, accompanied by a decrease in H3K9me3 levels and alterations in PcH organization. We further show that PHF2's PHD and catalytic domains are crucial for maintaining PcH stability, thereby safeguarding genome integrity. These results highlight the multifaceted nature of PHF2's functions in maintaining heterochromatin stability and regulating gene expression during neural development. Our study unravels the intricate relationship between heterochromatin stability and progenitor proliferation during mammalian neurogenesis.
Collapse
Affiliation(s)
- Samuel Aguirre
- Department of Structural and Molecular Biology, Instituto de Biología Molecular de Barcelona (IBMB), Consejo Superior de Investigaciones Científicas (CSIC), Barcelona, 08028, Spain
| | - Stella Pappa
- Department of Structural and Molecular Biology, Instituto de Biología Molecular de Barcelona (IBMB), Consejo Superior de Investigaciones Científicas (CSIC), Barcelona, 08028, Spain
| | - Núria Serna-Pujol
- Department of Structural and Molecular Biology, Instituto de Biología Molecular de Barcelona (IBMB), Consejo Superior de Investigaciones Científicas (CSIC), Barcelona, 08028, Spain
| | - Natalia Padilla
- Vall d'Hebron Institute of Research (VHIR), Passeig de la Vall d'Hebron, 119, E-08035, Barcelona, Spain
| | - Simona Iacobucci
- Department of Structural and Molecular Biology, Instituto de Biología Molecular de Barcelona (IBMB), Consejo Superior de Investigaciones Científicas (CSIC), Barcelona, 08028, Spain
| | - A Silvina Nacht
- Center for Genomic Regulation (CRG), Barcelona Institute for Science and Technology (BIST), Barcelona, Spain
- Universitat Pompeu Fabra (UPF), Barcelona, Spain
| | - Guillermo P Vicent
- Department of Structural and Molecular Biology, Instituto de Biología Molecular de Barcelona (IBMB), Consejo Superior de Investigaciones Científicas (CSIC), Barcelona, 08028, Spain
| | - Albert Jordan
- Department of Structural and Molecular Biology, Instituto de Biología Molecular de Barcelona (IBMB), Consejo Superior de Investigaciones Científicas (CSIC), Barcelona, 08028, Spain
| | - Xavier de la Cruz
- Vall d'Hebron Institute of Research (VHIR), Passeig de la Vall d'Hebron, 119, E-08035, Barcelona, Spain
- Institut Català per la Recerca i Estudis Avançats (ICREA), Barcelona, 08018, Spain
| | - Marian A Martínez-Balbás
- Department of Structural and Molecular Biology, Instituto de Biología Molecular de Barcelona (IBMB), Consejo Superior de Investigaciones Científicas (CSIC), Barcelona, 08028, Spain.
| |
Collapse
|
3
|
Laspisa D, Illa-Berenguer E, Bang S, Schmitz RJ, Parrott W, Wallace J. Mining the Utricularia gibba genome for insulator-like elements for genetic engineering. FRONTIERS IN PLANT SCIENCE 2023; 14:1279231. [PMID: 38023853 PMCID: PMC10663240 DOI: 10.3389/fpls.2023.1279231] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Accepted: 10/16/2023] [Indexed: 12/01/2023]
Abstract
Introduction Gene expression is often controlled via cis-regulatory elements (CREs) that modulate the production of transcripts. For multi-gene genetic engineering and synthetic biology, precise control of transcription is crucial, both to insulate the transgenes from unwanted native regulation and to prevent readthrough or cross-regulation of transgenes within a multi-gene cassette. To prevent this activity, insulator-like elements, more properly referred to as transcriptional blockers, could be inserted to separate the transgenes so that they are independently regulated. However, only a few validated insulator-like elements are available for plants, and they tend to be larger than ideal. Methods To identify additional potential insulator-like sequences, we conducted a genome-wide analysis of Utricularia gibba (humped bladderwort), one of the smallest known plant genomes, with genes that are naturally close together. The 10 best insulator-like candidates were evaluated in vivo for insulator-like activity. Results We identified a total of 4,656 intergenic regions with expression profiles suggesting insulator-like activity. Comparisons of these regions across 45 other plant species (representing Monocots, Asterids, and Rosids) show low levels of syntenic conservation of these regions. Genome-wide analysis of unmethylated regions (UMRs) indicates ~87% of the targeted regions are unmethylated; however, interpretation of this is complicated because U. gibba has remarkably low levels of methylation across the genome, so that large UMRs frequently extend over multiple genes and intergenic spaces. We also could not identify any conserved motifs among our selected intergenic regions or shared with existing insulator-like elements for plants. Despite this lack of conservation, however, testing of 10 selected intergenic regions for insulator-like activity found two elements on par with a previously published element (EXOB) while being significantly smaller. Discussion Given the small number of insulator-like elements currently available for plants, our results make a significant addition to available tools. The high hit rate (2 out of 10) also implies that more useful sequences are likely present in our selected intergenic regions; additional validation work will be required to identify which will be most useful for plant genetic engineering.
Collapse
Affiliation(s)
- Daniel Laspisa
- Center for Applied Genetic Technologies, University of Georgia, Athens, GA, United States
| | - Eudald Illa-Berenguer
- Center for Applied Genetic Technologies, University of Georgia, Athens, GA, United States
| | - Sohyun Bang
- Institute of Bioinformatics, University of Georgia, Athens, GA, United States
| | - Robert J. Schmitz
- Department of Genetics, University of Georgia, Athens, GA, United States
| | - Wayne Parrott
- Center for Applied Genetic Technologies, University of Georgia, Athens, GA, United States
- Department of Crop & Soil Science & Institute of Plant Breeding, Genetics and Genomics, University of Georgia, Athens, GA, United States
| | - Jason Wallace
- Center for Applied Genetic Technologies, University of Georgia, Athens, GA, United States
- Institute of Bioinformatics, University of Georgia, Athens, GA, United States
- Department of Crop & Soil Science & Institute of Plant Breeding, Genetics and Genomics, University of Georgia, Athens, GA, United States
| |
Collapse
|
4
|
Sidhwani P, Straight AF. Epigenetic inheritance and boundary maintenance at human centromeres. Curr Opin Struct Biol 2023; 82:102694. [PMID: 37657353 PMCID: PMC10530090 DOI: 10.1016/j.sbi.2023.102694] [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: 02/27/2023] [Revised: 07/31/2023] [Accepted: 08/07/2023] [Indexed: 09/03/2023]
Abstract
Centromeres are chromosomal regions that provide the foundation for microtubule attachment during chromosome segregation. Centromeres are epigenetically defined by nucleosomes containing the histone H3 variant centromere protein A (CENP-A) and, in many organisms, are surrounded by transcriptionally repressed pericentromeric chromatin marked by trimethylation of histone H3 lysine 9 (H3K9me3). Pericentromeric regions facilitate sister chromatid cohesion during mitosis, thereby supporting centromere function. Heterochromatin has a known propensity to spread into adjacent euchromatic domains unless it is properly bounded. Heterochromatin spreading into the centromere can disrupt kinetochore function, perturbing chromosome segregation and genome stability. In the fission yeast Schizosaccharomyces pombe, tRNA genes provide barriers to heterochromatin spread at the centromere, the absence of which results in abnormal meiotic chromosome segregation. How heterochromatin-centromere boundaries are established in humans is not understood. We propose models for stable epigenetic inheritance of centromeric domains in humans and discuss advances that will enable the discovery of novel regulators of this process.
Collapse
Affiliation(s)
- Pragya Sidhwani
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA, United States. https://twitter.com/@pra_sidh
| | - Aaron F Straight
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA, United States.
| |
Collapse
|
5
|
Sachs P, Bergmaier P, Treutwein K, Mermoud JE. The Conserved Chromatin Remodeler SMARCAD1 Interacts with TFIIIC and Architectural Proteins in Human and Mouse. Genes (Basel) 2023; 14:1793. [PMID: 37761933 PMCID: PMC10530723 DOI: 10.3390/genes14091793] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Revised: 09/08/2023] [Accepted: 09/08/2023] [Indexed: 09/29/2023] Open
Abstract
In vertebrates, SMARCAD1 participates in transcriptional regulation, heterochromatin maintenance, DNA repair, and replication. The molecular basis underlying its involvement in these processes is not well understood. We identified the RNA polymerase III general transcription factor TFIIIC as an interaction partner of native SMARCAD1 in mouse and human models using endogenous co-immunoprecipitations. TFIIIC has dual functionality, acting as a general transcription factor and as a genome organizer separating chromatin domains. We found that its partnership with SMARCAD1 is conserved across different mammalian cell types, from somatic to pluripotent cells. Using purified proteins, we confirmed that their interaction is direct. A gene expression analysis suggested that SMARCAD1 is dispensable for TFIIIC function as an RNA polymerase III transcription factor in mouse ESCs. The distribution of TFIIIC and SMARCAD1 in the ESC genome is distinct, and unlike in yeast, SMARCAD1 is not enriched at active tRNA genes. Further analysis of SMARCAD1-binding partners in pluripotent and differentiated mammalian cells reveals that SMARCAD1 associates with several factors that have key regulatory roles in chromatin organization, such as cohesin, laminB, and DDX5. Together, our work suggests for the first time that the SMARCAD1 enzyme participates in genome organization in mammalian nuclei through interactions with architectural proteins.
Collapse
Affiliation(s)
- Parysatis Sachs
- Institute of Molecular Biology and Tumor Research, Philipps University Marburg, 35043 Marburg, Germany
- CMC Development, R&D, Sanofi, 65926 Frankfurt, Germany
| | - Philipp Bergmaier
- Institute of Molecular Biology and Tumor Research, Philipps University Marburg, 35043 Marburg, Germany
- Global Development Operations, R&D, Merck Healthcare, 64293 Darmstadt, Germany
| | - Katrin Treutwein
- Institute of Molecular Biology and Tumor Research, Philipps University Marburg, 35043 Marburg, Germany
| | - Jacqueline E. Mermoud
- Institute of Molecular Biology and Tumor Research, Philipps University Marburg, 35043 Marburg, Germany
| |
Collapse
|
6
|
Tian K, Wang R, Huang J, Wang H, Ji X. Subcellular localization shapes the fate of RNA polymerase III. Cell Rep 2023; 42:112941. [PMID: 37556328 DOI: 10.1016/j.celrep.2023.112941] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Revised: 07/19/2023] [Accepted: 07/20/2023] [Indexed: 08/11/2023] Open
Abstract
RNA polymerase III (Pol III) plays a vital role in transcription and as a viral-DNA sensor, but how it is assembled and distributed within cells remains poorly understood. Here, we show that Pol III is assembled with chaperones in the cytoplasm and forms transcription-dependent protein clusters upon transport into the nucleus. The largest subunit (RPC1) depletion through an auxin-inducible degron leads to rapid degradation and disassembly of Pol III complex in the nucleus and cytoplasm, respectively. This generates a pool of partially assembled Pol III intermediates, which can be rapidly mobilized into the nucleus upon the restoration of RPC1. Our study highlights the critical role of subcellular localization in determining Pol III's fate and provides insight into the dynamic regulation of nuclear Pol III levels and the origin of cytoplasmic Pol III complexes involved in mediating viral immunity.
Collapse
Affiliation(s)
- Kai Tian
- Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education, School of Life Sciences, Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China
| | - Rui Wang
- Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education, School of Life Sciences, Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China
| | - Jie Huang
- Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education, School of Life Sciences, Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China
| | - Hui Wang
- Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education, School of Life Sciences, Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China
| | - Xiong Ji
- Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education, School of Life Sciences, Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China.
| |
Collapse
|
7
|
Tsunemine S, Nakagawa H, Suzuki Y, Murakami Y. The chromatin remodeler RSC prevents ectopic CENP-A propagation into pericentromeric heterochromatin at the chromatin boundary. Nucleic Acids Res 2022; 50:10914-10928. [PMID: 36200823 DOI: 10.1093/nar/gkac827] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2022] [Revised: 09/05/2022] [Accepted: 10/01/2022] [Indexed: 01/22/2023] Open
Abstract
Centromeres of most eukaryotes consist of two distinct chromatin domains: a kinetochore domain, identified by the histone H3 variant, CENP-A, and a heterochromatic domain. How these two domains are separated is unclear. Here, we show that, in Schizosaccharomyces pombe, mutation of the chromatin remodeler RSC induced CENP-ACnp1 misloading at pericentromeric heterochromatin, resulting in the mis-assembly of kinetochore proteins and a defect in chromosome segregation. We find that RSC functions at the kinetochore boundary to prevent CENP-ACnp1 from spreading into neighbouring heterochromatin, where deacetylated histones provide an ideal environment for the spread of CENP-ACnp1. In addition, we show that RSC decompacts the chromatin structure at this boundary, and propose that this RSC-directed chromatin decompaction prevents mis-propagation of CENP-ACnp1 into pericentromeric heterochromatin. Our study provides an insight into how the distribution of distinct chromatin domains is established and maintained.
Collapse
Affiliation(s)
- Satoru Tsunemine
- Laboratory of Bioorganic Chemistry, Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan.,Laboratory of Cell Regulation, Graduate School of Biostudies, Kyoto University, Kyoto 606-8501, Japan
| | - Hiromi Nakagawa
- Laboratory of Cell Regulation, Department of Viral Oncology, Institute for Virus Research, Kyoto University, Kyoto 606-8507, Japan
| | - Yutaka Suzuki
- Department of Computational Biology and Medical Science, Graduate School of Frontier Sciences, University of Tokyo, Kashiwa 277-8562, Japan
| | - Yota Murakami
- Laboratory of Bioorganic Chemistry, Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan
| |
Collapse
|
8
|
Wu W, McHugh T, Kelly DA, Pidoux AL, Allshire RC. Establishment of centromere identity is dependent on nuclear spatial organization. Curr Biol 2022; 32:3121-3136.e6. [PMID: 35830853 PMCID: PMC9616734 DOI: 10.1016/j.cub.2022.06.048] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2021] [Revised: 04/24/2022] [Accepted: 06/15/2022] [Indexed: 11/15/2022]
Abstract
The establishment of centromere-specific CENP-A chromatin is influenced by epigenetic and genetic processes. Central domain sequences from fission yeast centromeres are preferred substrates for CENP-ACnp1 incorporation, but their use is context dependent, requiring adjacent heterochromatin. CENP-ACnp1 overexpression bypasses heterochromatin dependency, suggesting that heterochromatin ensures exposure to conditions or locations permissive for CENP-ACnp1 assembly. Centromeres cluster around spindle-pole bodies (SPBs). We show that heterochromatin-bearing minichromosomes localize close to SPBs, consistent with this location promoting CENP-ACnp1 incorporation. We demonstrate that heterochromatin-independent de novo CENP-ACnp1 chromatin assembly occurs when central domain DNA is placed near, but not far from, endogenous centromeres or neocentromeres. Moreover, direct tethering of central domain DNA at SPBs permits CENP-ACnp1 assembly, suggesting that the nuclear compartment surrounding SPBs is permissive for CENP-ACnp1 incorporation because target sequences are exposed to high levels of CENP-ACnp1 and associated assembly factors. Thus, nuclear spatial organization is a key epigenetic factor that influences centromere identity.
Collapse
Affiliation(s)
- Weifang Wu
- Wellcome Trust Centre for Cell Biology, Institute of Cell Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh EH9 3BF, Scotland, UK
| | - Toni McHugh
- Wellcome Trust Centre for Cell Biology, Institute of Cell Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh EH9 3BF, Scotland, UK
| | - David A Kelly
- Wellcome Trust Centre for Cell Biology, Institute of Cell Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh EH9 3BF, Scotland, UK
| | - Alison L Pidoux
- Wellcome Trust Centre for Cell Biology, Institute of Cell Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh EH9 3BF, Scotland, UK
| | - Robin C Allshire
- Wellcome Trust Centre for Cell Biology, Institute of Cell Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh EH9 3BF, Scotland, UK.
| |
Collapse
|
9
|
Sizer RE, Chahid N, Butterfield SP, Donze D, Bryant NJ, White RJ. TFIIIC-based chromatin insulators through eukaryotic evolution. Gene X 2022; 835:146533. [PMID: 35623477 DOI: 10.1016/j.gene.2022.146533] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Revised: 04/19/2022] [Accepted: 04/29/2022] [Indexed: 11/04/2022] Open
Abstract
Eukaryotic chromosomes are divided into domains with distinct structural and functional properties, such as differing levels of chromatin compaction and gene transcription. Domains of relatively compact chromatin and minimal transcription are termed heterochromatic, whereas euchromatin is more open and actively transcribed. Insulators separate these domains and maintain their distinct features. Disruption of insulators can cause diseases such as cancer. Many insulators contain tRNA genes (tDNAs), examples of which have been shown to block the spread of activating or silencing activities. This characteristic of specific tDNAs is conserved through evolution, such that human tDNAs can serve as barriers to the spread of silencing in fission yeast. Here we demonstrate that tDNAs from the methylotrophic fungus Pichia pastoris can function effectively as insulators in distantly-related budding yeast. Key to the function of tDNAs as insulators is TFIIIC, a transcription factor that is also required for their expression. TFIIIC binds additional loci besides tDNAs, some of which have insulator activity. Although the mechanistic basis of TFIIIC-based insulation has been studied extensively in yeast, it is largely uncharacterized in metazoa. Utilising publicly-available genome-wide ChIP-seq data, we consider the extent to which mechanisms conserved from yeast to man may suffice to allow efficient insulation by TFIIIC in the more challenging chromatin environments of metazoa and suggest features that may have been acquired during evolution to cope with new challenges. We demonstrate the widespread presence at human tDNAs of USF1, a transcription factor with well-established barrier activity in vertebrates. We predict that tDNA-based insulators in higher organisms have evolved through incorporation of modules, such as binding sites for factors like USF1 and CTCF that are absent from yeasts, thereby strengthening function and providing opportunities for regulation between cell types.
Collapse
Affiliation(s)
- Rebecca E Sizer
- Department of Biology, The University of York, York YO10 5DD, UK
| | - Nisreen Chahid
- Department of Biology, The University of York, York YO10 5DD, UK
| | | | - David Donze
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, USA
| | - Nia J Bryant
- Department of Biology, The University of York, York YO10 5DD, UK
| | - Robert J White
- Department of Biology, The University of York, York YO10 5DD, UK.
| |
Collapse
|
10
|
Greenstein RA, Ng H, Barrales RR, Tan C, Braun S, Al-Sady B. Local chromatin context regulates the genetic requirements of the heterochromatin spreading reaction. PLoS Genet 2022; 18:e1010201. [PMID: 35584134 PMCID: PMC9154106 DOI: 10.1371/journal.pgen.1010201] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Revised: 05/31/2022] [Accepted: 04/13/2022] [Indexed: 11/18/2022] Open
Abstract
Heterochromatin spreading, the expansion of repressive chromatin structure from sequence-specific nucleation sites, is critical for stable gene silencing. Spreading re-establishes gene-poor constitutive heterochromatin across cell cycles but can also invade gene-rich euchromatin de novo to steer cell fate decisions. How chromatin context (i.e. euchromatic, heterochromatic) or different nucleation pathways influence heterochromatin spreading remains poorly understood. Previously, we developed a single-cell sensor in fission yeast that can separately record heterochromatic gene silencing at nucleation sequences and distal sites. Here we couple our quantitative assay to a genetic screen to identify genes encoding nuclear factors linked to the regulation of heterochromatin nucleation and the distal spreading of gene silencing. We find that mechanisms underlying gene silencing distal to a nucleation site differ by chromatin context. For example, Clr6 histone deacetylase complexes containing the Fkh2 transcription factor are specifically required for heterochromatin spreading at constitutive sites. Fkh2 recruits Clr6 to nucleation-distal chromatin sites in such contexts. In addition, we find that a number of chromatin remodeling complexes antagonize nucleation-distal gene silencing. Our results separate the regulation of heterochromatic gene silencing at nucleation versus distal sites and show that it is controlled by context-dependent mechanisms. The results of our genetic analysis constitute a broad community resource that will support further analysis of the mechanisms underlying the spread of epigenetic silencing along chromatin. Repressive structures, or heterochromatin, are seeded at specific genome sequences and then “spread” to silence nearby chromosomal regions. While much is known about the factors that seed heterochromatin, the genetic requirements for spreading are less clear. We devised a fission yeast single-cell method to examine how gene silencing is propagated by the heterochromatin spreading process specifically. Here we use this platform to ask if specific genes are required for the spreading process and whether the same or different genes direct spreading from different chromosomal seeding sites. We find a significant number of genes that specifically promote or antagonize the heterochromatin spreading process. However, different genes are required to enact spreading from different seeding sites. These results have potential implications for cell fate specification, where genes are newly silenced by heterochromatin spreading from diverse chromosomal sites. In a central finding, we show that the Clr6 protein complex, which removes chromatin marks linked to active genes, associates with the Forkhead 2 transcription factor to promote spreading of silencing structures from seeding sites at numerous chromosomal loci. In contrast, we show that proteins that remodel chromatin antagonize the spreading of gene silencing.
Collapse
Affiliation(s)
- R. A. Greenstein
- Department of Microbiology &Immunology, George Williams Hooper Foundation, University of California San Francisco, San Francisco, California, United States of America
- TETRAD graduate program, University of California San Francisco, San Francisco, California, United States of America
| | - Henry Ng
- Department of Microbiology &Immunology, George Williams Hooper Foundation, University of California San Francisco, San Francisco, California, United States of America
- TETRAD graduate program, University of California San Francisco, San Francisco, California, United States of America
| | - Ramon R. Barrales
- Biomedical Center, Department of Physiological Chemistry, Ludwig-Maximilians-Universität of Munich, Planegg-Martinsried, Germany
| | - Catherine Tan
- Department of Cell and Tissue Biology, University of California San Francisco, San Francisco, California, United States of America
- Biomedical Sciences graduate program, University of California San Francisco, San Francisco, California, United States of America
| | - Sigurd Braun
- Biomedical Center, Department of Physiological Chemistry, Ludwig-Maximilians-Universität of Munich, Planegg-Martinsried, Germany
- Institute for Genetics, Justus-Liebig University Giessen, Giessen, Germany
| | - Bassem Al-Sady
- Department of Microbiology &Immunology, George Williams Hooper Foundation, University of California San Francisco, San Francisco, California, United States of America
- * E-mail:
| |
Collapse
|
11
|
Oh J, Yeom S, Park J, Lee JS. The regional sequestration of heterochromatin structural proteins is critical to form and maintain silent chromatin. Epigenetics Chromatin 2022; 15:5. [PMID: 35101096 PMCID: PMC8805269 DOI: 10.1186/s13072-022-00435-w] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Accepted: 01/06/2022] [Indexed: 12/20/2022] Open
Abstract
Budding yeast Saccharomyces cerevisiae and fission yeast Schizosaccharomyces pombe are good models for heterochromatin study. In S. pombe, H3K9 methylation and Swi6, an ortholog of mammalian HP1, lead to heterochromatin formation. However, S. cerevisiae does not have known epigenetic silencing markers and instead has Sir proteins to regulate silent chromatin formation. Although S. cerevisiae and S. pombe form and maintain heterochromatin via mechanisms that appear to be fundamentally different, they share important common features in the heterochromatin structural proteins. Heterochromatin loci are localized at the nuclear periphery by binding to perinuclear membrane proteins, thereby producing distinct heterochromatin foci, which sequester heterochromatin structural proteins. In this review, we discuss the nuclear peripheral anchoring of heterochromatin foci and its functional relevance to heterochromatin formation and maintenance.
Collapse
Affiliation(s)
- Junsoo Oh
- Department of Molecular Bioscience, College of Biomedical Science, Kangwon National University, 1 Kangwondeahak-gil, Chuncheon, 24341, Republic of Korea
| | - Soojin Yeom
- Department of Molecular Bioscience, College of Biomedical Science, Kangwon National University, 1 Kangwondeahak-gil, Chuncheon, 24341, Republic of Korea
| | - Jiyeon Park
- Department of Molecular Bioscience, College of Biomedical Science, Kangwon National University, 1 Kangwondeahak-gil, Chuncheon, 24341, Republic of Korea
| | - Jung-Shin Lee
- Department of Molecular Bioscience, College of Biomedical Science, Kangwon National University, 1 Kangwondeahak-gil, Chuncheon, 24341, Republic of Korea.
| |
Collapse
|
12
|
Kurbidaeva A, Purugganan M. Insulators in Plants: Progress and Open Questions. Genes (Basel) 2021; 12:genes12091422. [PMID: 34573404 PMCID: PMC8470105 DOI: 10.3390/genes12091422] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Revised: 09/08/2021] [Accepted: 09/14/2021] [Indexed: 11/16/2022] Open
Abstract
The genomes of higher eukaryotes are partitioned into topologically associated domains or TADs, and insulators (also known as boundary elements) are the key elements responsible for their formation and maintenance. Insulators were first identified and extensively studied in Drosophila as well as mammalian genomes, and have also been described in yeast and plants. In addition, many insulator proteins are known in Drosophila, and some have been investigated in mammals. However, much less is known about this important class of non-coding DNA elements in plant genomes. In this review, we take a detailed look at known plant insulators across different species and provide an overview of potential determinants of plant insulator functions, including cis-elements and boundary proteins. We also discuss methods previously used in attempts to identify plant insulators, provide a perspective on their importance for research and biotechnology, and discuss areas of potential future research.
Collapse
|
13
|
Guimarães AR, Correia I, Sousa I, Oliveira C, Moura G, Bezerra AR, Santos MAS. tRNAs as a Driving Force of Genome Evolution in Yeast. Front Microbiol 2021; 12:634004. [PMID: 33776966 PMCID: PMC7990762 DOI: 10.3389/fmicb.2021.634004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Accepted: 02/01/2021] [Indexed: 11/29/2022] Open
Abstract
Transfer RNAs (tRNAs) are widely known for their roles in the decoding of the linear mRNA information into amino acid sequences of proteins. They are also multifunctional platforms in the translation process and have other roles beyond translation, including sensing amino acid abundance, interacting with the general stress response machinery, and modulating cellular adaptation, survival, and death. In this mini-review, we focus on the emerging role of tRNA genes in the organization and modification of the genomic architecture of yeast and the role of tRNA misexpression and decoding infidelity in genome stability, evolution, and adaption. We discuss published work showing how quickly tRNA genes can mutate to meet novel translational demands, how tRNAs speed up genome evolution, and how tRNA genes can be sites of genomic instability. We highlight recent works showing that loss of tRNA decoding fidelity and small alterations in tRNA expression have unexpected and profound impacts on genome stability. By dissecting these recent evidence, we hope to lay the groundwork that prompts future investigations on the mechanistic interplay between tRNAs and genome modification that likely triggers genome evolution.
Collapse
Affiliation(s)
- Ana Rita Guimarães
- Department of Medical Sciences, Institute of Biomedicine - iBiMED, University of Aveiro, Aveiro, Portugal
| | - Inês Correia
- Department of Medical Sciences, Institute of Biomedicine - iBiMED, University of Aveiro, Aveiro, Portugal
| | - Inês Sousa
- Department of Medical Sciences, Institute of Biomedicine - iBiMED, University of Aveiro, Aveiro, Portugal
| | - Carla Oliveira
- Department of Medical Sciences, Institute of Biomedicine - iBiMED, University of Aveiro, Aveiro, Portugal
| | - Gabriela Moura
- Department of Medical Sciences, Institute of Biomedicine - iBiMED, University of Aveiro, Aveiro, Portugal
| | - Ana Rita Bezerra
- Department of Medical Sciences, Institute of Biomedicine - iBiMED, University of Aveiro, Aveiro, Portugal
| | - Manuel A S Santos
- Department of Medical Sciences, Institute of Biomedicine - iBiMED, University of Aveiro, Aveiro, Portugal
| |
Collapse
|
14
|
Storck WK, Bicocca VT, Rountree MR, Honda S, Ormsby T, Selker EU. LSD1 prevents aberrant heterochromatin formation in Neurospora crassa. Nucleic Acids Res 2020; 48:10199-10210. [PMID: 32946564 PMCID: PMC7544195 DOI: 10.1093/nar/gkaa724] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Revised: 08/17/2020] [Accepted: 09/16/2020] [Indexed: 12/25/2022] Open
Abstract
Heterochromatin is a specialized form of chromatin that restricts access to DNA and inhibits genetic processes, including transcription and recombination. In Neurospora crassa, constitutive heterochromatin is characterized by trimethylation of lysine 9 on histone H3, hypoacetylation of histones, and DNA methylation. We explored whether the conserved histone demethylase, lysine-specific demethylase 1 (LSD1), regulates heterochromatin in Neurospora, and if so, how. Though LSD1 is implicated in heterochromatin regulation, its function is inconsistent across different systems; orthologs of LSD1 have been shown to either promote or antagonize heterochromatin expansion by removing H3K4me or H3K9me respectively. We identify three members of the Neurospora LSD complex (LSDC): LSD1, PHF1, and BDP-1. Strains deficient for any of these proteins exhibit variable spreading of heterochromatin and establishment of new heterochromatin domains throughout the genome. Although establishment of H3K9me3 is typically independent of DNA methylation in Neurospora, instances of DNA methylation-dependent H3K9me3 have been found outside regions of canonical heterochromatin. Consistent with this, the hyper-H3K9me3 phenotype of Δlsd1 strains is dependent on the presence of DNA methylation, as well as HCHC-mediated histone deacetylation, suggesting that spreading is dependent on some feedback mechanism. Altogether, our results suggest LSD1 works in opposition to HCHC to maintain proper heterochromatin boundaries.
Collapse
Affiliation(s)
- William K Storck
- Institute of Molecular Biology, University of Oregon, Eugene, OR 97403, USA
| | - Vincent T Bicocca
- Institute of Molecular Biology, University of Oregon, Eugene, OR 97403, USA
| | - Michael R Rountree
- Institute of Molecular Biology, University of Oregon, Eugene, OR 97403, USA
| | - Shinji Honda
- Faculty of Medical Sciences, University of Fukui, Fukui 910-1193, Japan
| | - Tereza Ormsby
- Institute of Molecular Biology, University of Oregon, Eugene, OR 97403, USA
| | - Eric U Selker
- Institute of Molecular Biology, University of Oregon, Eugene, OR 97403, USA
| |
Collapse
|
15
|
Abstract
The fission yeast silent mating-type region provides an excellent system to ask how chromatic domains with opposite effects on gene expression coexist side by side along chromosomes and to investigate roles played by DNA elements and architectural proteins in the phenomenon. By showing that the IR-L and IR-R chromatin boundaries favor heterochromatin formation in the domain that separates them, dependent on each other and on binding sites for the architectural factor TFIIIC, our work brings to light an important function of these elements and supports the notion that similar types of interactions between boundaries might in other organisms as well stimulate heterochromatin formation in intervening chromosomal loops to actively shape gene expression landscapes. In fission yeast, the inverted repeats IR-L and IR-R function as boundary elements at the edges of a 20-kb silent heterochromatic domain where nucleosomes are methylated at histone H3K9. Each repeat contains a series of B-box motifs physically associated with the architectural TFIIIC complex and with other factors including the replication regulator Sap1 and the Rix1 complex (RIXC). We demonstrate here the activity of these repeats in heterochromatin formation and maintenance. Deletion of the entire IR-R repeat or, to a lesser degree, deletion of just the B boxes impaired the de novo establishment of the heterochromatic domain. Nucleation proceeded normally at the RNA interference (RNAi)-dependent element cenH but subsequent propagation to the rest of the region occurred at reduced rates in the mutants. Once established, heterochromatin was unstable in the mutants. These defects resulted in bistable populations of cells occupying alternate “on” and “off” epigenetic states. Deleting IR-L in combination with IR-R synergistically tipped the balance toward the derepressed state, revealing a concerted action of the two boundaries at a distance. The nuclear rim protein Amo1 has been proposed to tether the mating-type region and its boundaries to the nuclear envelope, where Amo1 mutants displayed milder phenotypes than boundary mutants. Thus, the boundaries might facilitate heterochromatin propagation and maintenance in ways other than just through Amo1, perhaps by constraining a looped domain through pairing.
Collapse
|
16
|
Genetic circuit design automation for yeast. Nat Microbiol 2020; 5:1349-1360. [DOI: 10.1038/s41564-020-0757-2] [Citation(s) in RCA: 58] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Accepted: 06/17/2020] [Indexed: 11/08/2022]
|
17
|
Martins NMC, Cisneros-Soberanis F, Pesenti E, Kochanova NY, Shang WH, Hori T, Nagase T, Kimura H, Larionov V, Masumoto H, Fukagawa T, Earnshaw WC. H3K9me3 maintenance on a human artificial chromosome is required for segregation but not centromere epigenetic memory. J Cell Sci 2020; 133:jcs242610. [PMID: 32576667 PMCID: PMC7390644 DOI: 10.1242/jcs.242610] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Accepted: 06/11/2020] [Indexed: 12/24/2022] Open
Abstract
Most eukaryotic centromeres are located within heterochromatic regions. Paradoxically, heterochromatin can also antagonize de novo centromere formation, and some centromeres lack it altogether. In order to investigate the importance of heterochromatin at centromeres, we used epigenetic engineering of a synthetic alphoidtetO human artificial chromosome (HAC), to which chimeric proteins can be targeted. By tethering the JMJD2D demethylase (also known as KDM4D), we removed heterochromatin mark H3K9me3 (histone 3 lysine 9 trimethylation) specifically from the HAC centromere. This caused no short-term defects, but long-term tethering reduced HAC centromere protein levels and triggered HAC mis-segregation. However, centromeric CENP-A was maintained at a reduced level. Furthermore, HAC centromere function was compatible with an alternative low-H3K9me3, high-H3K27me3 chromatin signature, as long as residual levels of H3K9me3 remained. When JMJD2D was released from the HAC, H3K9me3 levels recovered over several days back to initial levels along with CENP-A and CENP-C centromere levels, and mitotic segregation fidelity. Our results suggest that a minimal level of heterochromatin is required to stabilize mitotic centromere function but not for maintaining centromere epigenetic memory, and that a homeostatic pathway maintains heterochromatin at centromeres.This article has an associated First Person interview with the first authors of the paper.
Collapse
Affiliation(s)
| | | | - Elisa Pesenti
- Wellcome Trust Centre for Cell Biology, Edinburgh, UK
| | | | - Wei-Hao Shang
- Graduate School of Frontier Biosciences, Osaka University, Osaka, Japan
| | - Tetsuya Hori
- Graduate School of Frontier Biosciences, Osaka University, Osaka, Japan
| | | | - Hiroshi Kimura
- Cell Biology Unit, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama, Japan
| | - Vladimir Larionov
- National Cancer Institute, National Institutes of Health, Bethesda, USA
| | | | - Tatsuo Fukagawa
- Graduate School of Frontier Biosciences, Osaka University, Osaka, Japan
| | | |
Collapse
|
18
|
Overlapping but Distinct Sequences Play Roles in the Insulator and Promoter Activities of the Drosophila BEAF-Dependent scs' Insulator. Genetics 2020; 215:1003-1012. [PMID: 32554599 DOI: 10.1534/genetics.120.303344] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Accepted: 06/16/2020] [Indexed: 12/30/2022] Open
Abstract
Chromatin domain insulators are thought to help partition the genome into genetic units called topologically associating domains (TADs). In Drosophila, TADs are often separated by inter-TAD regions containing active housekeeping genes and associated insulator binding proteins. This raises the question of whether insulator binding proteins are involved primarily in chromosomal TAD architecture or gene activation, or if these two activities are linked. The Boundary Element-Associated Factor of 32 kDa (BEAF-32, or BEAF for short) is usually found in inter-TADs. BEAF was discovered based on binding to the scs' insulator, and is important for the insulator activity of scs' and other BEAF binding sites. There are divergent promoters in scs' with a BEAF binding site by each. Here, we dissect the scs' insulator to identify DNA sequences important for insulator and promoter activity, focusing on the half of scs' with a high affinity BEAF binding site. We find that the BEAF binding site is important for both insulator and promoter activity, as is another sequence we refer to as LS4. Aside from that, different sequences play roles in insulator and promoter activity. So while there is overlap and BEAF is important for both, insulator and promoter activity can be separated.
Collapse
|
19
|
Ohzeki JI, Otake K, Masumoto H. Human artificial chromosome: Chromatin assembly mechanisms and CENP-B. Exp Cell Res 2020; 389:111900. [PMID: 32044309 DOI: 10.1016/j.yexcr.2020.111900] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2019] [Revised: 02/04/2020] [Accepted: 02/07/2020] [Indexed: 12/12/2022]
Abstract
The centromere is a specialized chromosomal locus required for accurate chromosome segregation. Heterochromatin also assembles around centromere chromatin and forms a base that supports sister chromatid cohesion until anaphase begins. Both centromere chromatin and heterochromatin assemble on a centromeric DNA sequence, a highly repetitive sequence called alphoid DNA (α-satellite DNA) in humans. Alphoid DNA can form a de novo centromere and subsequent human artificial chromosome (HAC) when introduced into the human culture cells HT1080. HAC is maintained stably as a single chromosome independent of other human chromosomes. For de novo centromere assembly and HAC formation, the centromere protein CENP-B and its binding sites, CENP-B boxes, are required in the repeating units of alphoid DNA. CENP-B has multiple roles in de novo centromere chromatin assembly and stabilization and in heterochromatin formation upon alphoid DNA introduction into the cells. Here we review recent progress in human artificial chromosome construction and centromere/heterochromatin assembly and maintenance, focusing on the involvement of human centromere DNA and CENP-B protein.
Collapse
Affiliation(s)
- Jun-Ichirou Ohzeki
- Laboratory of Chromosome Engineering, Department of Frontier Research and Development, Kazusa DNA Research Institute, 2-6-7 Kazusa-Kamatari, Kisarazu, 292-0818, Japan
| | - Koichiro Otake
- Laboratory of Chromosome Engineering, Department of Frontier Research and Development, Kazusa DNA Research Institute, 2-6-7 Kazusa-Kamatari, Kisarazu, 292-0818, Japan
| | - Hiroshi Masumoto
- Laboratory of Chromosome Engineering, Department of Frontier Research and Development, Kazusa DNA Research Institute, 2-6-7 Kazusa-Kamatari, Kisarazu, 292-0818, Japan.
| |
Collapse
|
20
|
Fang Y, Coelho MA, Shu H, Schotanus K, Thimmappa BC, Yadav V, Chen H, Malc EP, Wang J, Mieczkowski PA, Kronmiller B, Tyler BM, Sanyal K, Dong S, Nowrousian M, Heitman J. Long transposon-rich centromeres in an oomycete reveal divergence of centromere features in Stramenopila-Alveolata-Rhizaria lineages. PLoS Genet 2020; 16:e1008646. [PMID: 32150559 PMCID: PMC7082073 DOI: 10.1371/journal.pgen.1008646] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Revised: 03/19/2020] [Accepted: 02/03/2020] [Indexed: 12/11/2022] Open
Abstract
Centromeres are chromosomal regions that serve as platforms for kinetochore assembly and spindle attachments, ensuring accurate chromosome segregation during cell division. Despite functional conservation, centromere DNA sequences are diverse and often repetitive, making them challenging to assemble and identify. Here, we describe centromeres in an oomycete Phytophthora sojae by combining long-read sequencing-based genome assembly and chromatin immunoprecipitation for the centromeric histone CENP-A followed by high-throughput sequencing (ChIP-seq). P. sojae centromeres cluster at a single focus at different life stages and during nuclear division. We report an improved genome assembly of the P. sojae reference strain, which enabled identification of 15 enriched CENP-A binding regions as putative centromeres. By focusing on a subset of these regions, we demonstrate that centromeres in P. sojae are regional, spanning 211 to 356 kb. Most of these regions are transposon-rich, poorly transcribed, and lack the histone modification H3K4me2 but are embedded within regions with the heterochromatin marks H3K9me3 and H3K27me3. Strikingly, we discovered a Copia-like transposon (CoLT) that is highly enriched in the CENP-A chromatin. Similar clustered elements are also found in oomycete relatives of P. sojae, and may be applied as a criterion for prediction of oomycete centromeres. This work reveals a divergence of centromere features in oomycetes as compared to other organisms in the Stramenopila-Alveolata-Rhizaria (SAR) supergroup including diatoms and Plasmodium falciparum that have relatively short and simple regional centromeres. Identification of P. sojae centromeres in turn also advances the genome assembly. Oomycetes are fungal-like microorganisms that belong to the stramenopiles within the Stramenopila-Alveolata-Rhizaria (SAR) supergroup. The Phytophthora oomycetes are infamous as plant killers, threatening crop production worldwide. Because of the highly repetitive nature of their genomes, assembly of oomycete genomes presents challenges that impede identification of centromeres, which are chromosomal sites mediating faithful chromosome segregation. We report long-read sequencing-based genome assembly of the Phytophthora sojae reference strain, which facilitated the discovery of centromeres. P. sojae harbors large regional centromeres fully embedded in heterochromatin, and enriched for a Copia-like transposon that is also found in discrete clusters in other oomycetes. This study provides insight into the oomycete genome organization, broadens our knowledge of centromere structure, function and evolution in eukaryotes, and may help elucidate the high frequency of aneuploidy during oomycete reproduction.
Collapse
Affiliation(s)
- Yufeng Fang
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Marco A. Coelho
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Haidong Shu
- College of Plant Protection, Nanjing Agricultural University, Nanjing, China
| | - Klaas Schotanus
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Bhagya C. Thimmappa
- Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, India
| | - Vikas Yadav
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Han Chen
- College of Plant Protection, Nanjing Agricultural University, Nanjing, China
| | - Ewa P. Malc
- Department of Genetics, University of North Carolina, Chapel Hill, North Carolina, United States of America
| | - Jeremy Wang
- Department of Genetics, University of North Carolina, Chapel Hill, North Carolina, United States of America
| | - Piotr A. Mieczkowski
- Department of Genetics, University of North Carolina, Chapel Hill, North Carolina, United States of America
| | - Brent Kronmiller
- Center for Genome Research and Biocomputing and Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon, United States of America
| | - Brett M. Tyler
- Center for Genome Research and Biocomputing and Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon, United States of America
| | - Kaustuv Sanyal
- Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, India
| | - Suomeng Dong
- College of Plant Protection, Nanjing Agricultural University, Nanjing, China
| | - Minou Nowrousian
- Lehrstuhl fuer Molekulare und Zellulaere Botanik, Ruhr-Universitaet Bochum, Bochum, Germany
| | - Joseph Heitman
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, United States of America
- * E-mail:
| |
Collapse
|
21
|
Greenstein RA, Barrales RR, Sanchez NA, Bisanz JE, Braun S, Al-Sady B. Set1/COMPASS repels heterochromatin invasion at euchromatic sites by disrupting Suv39/Clr4 activity and nucleosome stability. Genes Dev 2020; 34:99-117. [PMID: 31805521 PMCID: PMC6938669 DOI: 10.1101/gad.328468.119] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Accepted: 10/30/2019] [Indexed: 12/27/2022]
Abstract
Protection of euchromatin from invasion by gene-repressive heterochromatin is critical for cellular health and viability. In addition to constitutive loci such as pericentromeres and subtelomeres, heterochromatin can be found interspersed in gene-rich euchromatin, where it regulates gene expression pertinent to cell fate. While heterochromatin and euchromatin are globally poised for mutual antagonism, the mechanisms underlying precise spatial encoding of heterochromatin containment within euchromatic sites remain opaque. We investigated ectopic heterochromatin invasion by manipulating the fission yeast mating type locus boundary using a single-cell spreading reporter system. We found that heterochromatin repulsion is locally encoded by Set1/COMPASS on certain actively transcribed genes and that this protective role is most prominent at heterochromatin islands, small domains interspersed in euchromatin that regulate cell fate specifiers. Sensitivity to invasion by heterochromatin, surprisingly, is not dependent on Set1 altering overall gene expression levels. Rather, the gene-protective effect is strictly dependent on Set1's catalytic activity. H3K4 methylation, the Set1 product, antagonizes spreading in two ways: directly inhibiting catalysis by Suv39/Clr4 and locally disrupting nucleosome stability. Taken together, these results describe a mechanism for spatial encoding of euchromatic signals that repel heterochromatin invasion.
Collapse
Affiliation(s)
- R A Greenstein
- Department of Microbiology and Immunology, George Williams Hooper Foundation, University of California at San Francisco, San Francisco, California 94143, USA
- TETRAD Graduate Program, University of California at San Francisco, San Francisco, California 94143, USA
| | - Ramon R Barrales
- Department of Physiological Chemistry, Biomedical Center (BMC), Ludwig Maximilians University of Munich, 82152 Martinsried, Germany
- International Max Planck Research School for Molecular and Cellular Life Sciences, 82152 Martinsried, Germany
| | - Nicholas A Sanchez
- Department of Microbiology and Immunology, George Williams Hooper Foundation, University of California at San Francisco, San Francisco, California 94143, USA
- TETRAD Graduate Program, University of California at San Francisco, San Francisco, California 94143, USA
| | - Jordan E Bisanz
- Department of Microbiology and Immunology, George Williams Hooper Foundation, University of California at San Francisco, San Francisco, California 94143, USA
| | - Sigurd Braun
- Department of Physiological Chemistry, Biomedical Center (BMC), Ludwig Maximilians University of Munich, 82152 Martinsried, Germany
- International Max Planck Research School for Molecular and Cellular Life Sciences, 82152 Martinsried, Germany
| | - Bassem Al-Sady
- Department of Microbiology and Immunology, George Williams Hooper Foundation, University of California at San Francisco, San Francisco, California 94143, USA
| |
Collapse
|
22
|
Holla S, Dhakshnamoorthy J, Folco HD, Balachandran V, Xiao H, Sun LL, Wheeler D, Zofall M, Grewal SIS. Positioning Heterochromatin at the Nuclear Periphery Suppresses Histone Turnover to Promote Epigenetic Inheritance. Cell 2019; 180:150-164.e15. [PMID: 31883795 DOI: 10.1016/j.cell.2019.12.004] [Citation(s) in RCA: 79] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Revised: 09/29/2019] [Accepted: 12/04/2019] [Indexed: 01/09/2023]
Abstract
In eukaryotes, heterochromatin is generally located at the nuclear periphery. This study investigates the biological significance of perinuclear positioning for heterochromatin maintenance and gene silencing. We identify the nuclear rim protein Amo1NUPL2 as a factor required for the propagation of heterochromatin at endogenous and ectopic sites in the fission yeast genome. Amo1 associates with the Rix1PELP1-containing RNA processing complex RIXC and with the histone chaperone complex FACT. RIXC, which binds to heterochromatin protein Swi6HP1 across silenced chromosomal domains and to surrounding boundary elements, connects heterochromatin with Amo1 at the nuclear periphery. In turn, the Amo1-enriched subdomain is critical for Swi6 association with FACT that precludes histone turnover to promote gene silencing and preserve epigenetic stability of heterochromatin. In addition to uncovering conserved factors required for perinuclear positioning of heterochromatin, these analyses elucidate a mechanism by which a peripheral subdomain enforces stable gene repression and maintains heterochromatin in a heritable manner.
Collapse
Affiliation(s)
- Sahana Holla
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Jothy Dhakshnamoorthy
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - H Diego Folco
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Vanivilasini Balachandran
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Hua Xiao
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Ling-Ling Sun
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - David Wheeler
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Martin Zofall
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Shiv I S Grewal
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA.
| |
Collapse
|
23
|
Lawrimore CJ, Bloom K. Common Features of the Pericentromere and Nucleolus. Genes (Basel) 2019; 10:E1029. [PMID: 31835574 PMCID: PMC6947172 DOI: 10.3390/genes10121029] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Revised: 12/05/2019] [Accepted: 12/07/2019] [Indexed: 12/20/2022] Open
Abstract
Both the pericentromere and the nucleolus have unique characteristics that distinguish them amongst the rest of genome. Looping of pericentromeric DNA, due to structural maintenance of chromosome (SMC) proteins condensin and cohesin, drives its ability to maintain tension during metaphase. Similar loops are formed via condensin and cohesin in nucleolar ribosomal DNA (rDNA). Condensin and cohesin are also concentrated in transfer RNA (tRNA) genes, genes which may be located within the pericentromere as well as tethered to the nucleolus. Replication fork stalling, as well as downstream consequences such as genomic recombination, are characteristic of both the pericentromere and rDNA. Furthermore, emerging evidence suggests that the pericentromere may function as a liquid-liquid phase separated domain, similar to the nucleolus. We therefore propose that the pericentromere and nucleolus, in part due to their enrichment of SMC proteins and others, contain similar domains that drive important cellular activities such as segregation, stability, and repair.
Collapse
Affiliation(s)
| | - Kerry Bloom
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3280, USA;
| |
Collapse
|
24
|
Centromere repositioning causes inversion of meiosis and generates a reproductive barrier. Proc Natl Acad Sci U S A 2019; 116:21580-21591. [PMID: 31597736 PMCID: PMC6815110 DOI: 10.1073/pnas.1911745116] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Mutations in inner kinetochore components induce centromere repositioning without alteration in the centromeric DNA sequence, revealing a feedback mechanism underlying the high epigenetic stability of the centromere. This also provides a desirable experimental system to explore the functional significance of centromere positioning in meiosis. We discovered that in a heterozygotic meiosis, a repositioned centromere generates a reproductive barrier, suggesting a functional role of evolutionary new centromeres in speciation; furthermore, in a homozygotic meiosis, chromosomes carrying repositioned centromeres frequently undergo the 2 stages of meiotic segregation in an inverted order, demonstrating high flexibility in the meiotic process. The chromosomal position of each centromere is determined epigenetically and is highly stable, whereas incremental cases have supported the occurrence of centromere repositioning on an evolutionary time scale (evolutionary new centromeres, ENCs), which is thought to be important in speciation. The mechanisms underlying the high stability of centromeres and its functional significance largely remain an enigma. Here, in the fission yeast Schizosaccharomyces pombe, we identify a feedback mechanism: The kinetochore, whose assembly is guided by the centromere, in turn, enforces centromere stability. Upon going through meiosis, specific inner kinetochore mutations induce centromere repositioning—inactivation of the original centromere and formation of a new centromere elsewhere—in 1 of the 3 chromosomes at random. Repositioned centromeres reside asymmetrically in the pericentromeric regions and cells carrying them are competent in mitosis and homozygotic meiosis. However, when cells carrying a repositioned centromere are crossed with those carrying the original centromere, the progeny suffer severe lethality due to defects in meiotic chromosome segregation. Thus, repositioned centromeres constitute a reproductive barrier that could initiate genetic divergence between 2 populations with mismatched centromeres, documenting a functional role of ENCs in speciation. Surprisingly, homozygotic repositioned centromeres tend to undergo meiosis in an inverted order—that is, sister chromatids segregate first, and homologous chromosomes separate second—whereas the original centromeres on other chromosomes in the same cell undergo meiosis in the canonical order, revealing hidden flexibility in the perceived rigid process of meiosis.
Collapse
|
25
|
Sreekumar L, Jaitly P, Chen Y, Thimmappa BC, Sanyal A, Sanyal K. Cis- and Trans-chromosomal Interactions Define Pericentric Boundaries in the Absence of Conventional Heterochromatin. Genetics 2019; 212:1121-1132. [PMID: 31142612 PMCID: PMC6707466 DOI: 10.1534/genetics.119.302179] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Accepted: 05/22/2019] [Indexed: 01/28/2023] Open
Abstract
The diploid budding yeast Candida albicans harbors unique CENPA-rich 3- to 5-kb regions that form the centromere (CEN) core on each of its eight chromosomes. The epigenetic nature of these CENs does not permit the stabilization of a functional kinetochore on an exogenously introduced CEN plasmid. The flexible nature of such centromeric chromatin is exemplified by the reversible silencing of a transgene upon its integration into the CENPA-bound region. The lack of a conventional heterochromatin machinery and the absence of defined boundaries of CENPA chromatin makes the process of CEN specification in this organism elusive. Additionally, upon native CEN deletion, C. albicans can efficiently activate neocentromeres proximal to the native CEN locus, hinting at the importance of CEN-proximal regions. In this study, we examine this CEN-proximity effect and identify factors for CEN specification in C. albicans We exploit a counterselection assay to isolate cells that can silence a transgene when integrated into the CEN-flanking regions. We show that the frequency of reversible silencing of the transgene decreases from the central core of CEN7 to its peripheral regions. Using publicly available C. albicans high-throughput chromosome conformation capture data, we identify a 25-kb region centering on the CENPA-bound core that acts as CEN-flanking compact chromatin (CFCC). Cis- and trans-chromosomal interactions associated with the CFCC spatially segregates it from bulk chromatin. We further show that neocentromere activation on chromosome 7 occurs within this specified region. Hence, this study identifies a specialized CEN-proximal domain that specifies and restricts the centromeric activity to a unique region.
Collapse
Affiliation(s)
- Lakshmi Sreekumar
- Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560064, India
| | - Priya Jaitly
- Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560064, India
| | - Yao Chen
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore 637551
| | - Bhagya C Thimmappa
- Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560064, India
| | - Amartya Sanyal
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore 637551
| | - Kaustuv Sanyal
- Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560064, India
| |
Collapse
|
26
|
Tong P, Pidoux AL, Toda NRT, Ard R, Berger H, Shukla M, Torres-Garcia J, Müller CA, Nieduszynski CA, Allshire RC. Interspecies conservation of organisation and function between nonhomologous regional centromeres. Nat Commun 2019; 10:2343. [PMID: 31138803 PMCID: PMC6538654 DOI: 10.1038/s41467-019-09824-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Accepted: 03/27/2019] [Indexed: 01/31/2023] Open
Abstract
Despite the conserved essential function of centromeres, centromeric DNA itself is not conserved. The histone-H3 variant, CENP-A, is the epigenetic mark that specifies centromere identity. Paradoxically, CENP-A normally assembles on particular sequences at specific genomic locations. To gain insight into the specification of complex centromeres, here we take an evolutionary approach, fully assembling genomes and centromeres of related fission yeasts. Centromere domain organization, but not sequence, is conserved between Schizosaccharomyces pombe, S. octosporus and S. cryophilus with a central CENP-ACnp1 domain flanked by heterochromatic outer-repeat regions. Conserved syntenic clusters of tRNA genes and 5S rRNA genes occur across the centromeres of S. octosporus and S. cryophilus, suggesting conserved function. Interestingly, nonhomologous centromere central-core sequences from S. octosporus and S. cryophilus are recognized in S. pombe, resulting in cross-species establishment of CENP-ACnp1 chromatin and functional kinetochores. Therefore, despite the lack of sequence conservation, Schizosaccharomyces centromere DNA possesses intrinsic conserved properties that promote assembly of CENP-A chromatin.
Collapse
Affiliation(s)
- Pin Tong
- 0000 0004 1936 7988grid.4305.2Wellcome Centre for Cell Biology and Institute of Cell Biology, School of Biological Sciences, The University of Edinburgh, Mayfield Road, Edinburgh, EH9 3BF UK
| | - Alison L. Pidoux
- 0000 0004 1936 7988grid.4305.2Wellcome Centre for Cell Biology and Institute of Cell Biology, School of Biological Sciences, The University of Edinburgh, Mayfield Road, Edinburgh, EH9 3BF UK
| | - Nicholas R. T. Toda
- 0000 0004 1936 7988grid.4305.2Wellcome Centre for Cell Biology and Institute of Cell Biology, School of Biological Sciences, The University of Edinburgh, Mayfield Road, Edinburgh, EH9 3BF UK ,0000 0001 2203 0006grid.464101.6Present Address: UPMC CNRS, Roscoff Marine Station, Place Georges Teissier, 29680 Roscoff, France
| | - Ryan Ard
- 0000 0004 1936 7988grid.4305.2Wellcome Centre for Cell Biology and Institute of Cell Biology, School of Biological Sciences, The University of Edinburgh, Mayfield Road, Edinburgh, EH9 3BF UK ,0000 0001 0674 042Xgrid.5254.6Present Address: Copenhagen Plant Science Centre, University of Copenhagen, Bülowsvej 34, 1870 Frederiksberg C, Denmark
| | - Harald Berger
- 0000 0004 1936 7988grid.4305.2Wellcome Centre for Cell Biology and Institute of Cell Biology, School of Biological Sciences, The University of Edinburgh, Mayfield Road, Edinburgh, EH9 3BF UK ,0000 0001 2298 5320grid.5173.0Present Address: Symbiocyte, Universität für Bodenkultur Wien, University of Natural Resources and Life Sciences, 1180 Vienna, Austria
| | - Manu Shukla
- 0000 0004 1936 7988grid.4305.2Wellcome Centre for Cell Biology and Institute of Cell Biology, School of Biological Sciences, The University of Edinburgh, Mayfield Road, Edinburgh, EH9 3BF UK
| | - Jesus Torres-Garcia
- 0000 0004 1936 7988grid.4305.2Wellcome Centre for Cell Biology and Institute of Cell Biology, School of Biological Sciences, The University of Edinburgh, Mayfield Road, Edinburgh, EH9 3BF UK
| | - Carolin A. Müller
- 0000 0004 1936 8948grid.4991.5Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford, OX1 3RE UK
| | - Conrad A. Nieduszynski
- 0000 0004 1936 8948grid.4991.5Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford, OX1 3RE UK
| | - Robin C. Allshire
- 0000 0004 1936 7988grid.4305.2Wellcome Centre for Cell Biology and Institute of Cell Biology, School of Biological Sciences, The University of Edinburgh, Mayfield Road, Edinburgh, EH9 3BF UK
| |
Collapse
|
27
|
Ohzeki J, Larionov V, Earnshaw WC, Masumoto H. De novo formation and epigenetic maintenance of centromere chromatin. Curr Opin Cell Biol 2019; 58:15-25. [PMID: 30654232 DOI: 10.1016/j.ceb.2018.12.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Revised: 11/30/2018] [Accepted: 12/07/2018] [Indexed: 12/12/2022]
Abstract
Accurate chromosome segregation is essential for cell proliferation. The centromere is a specialized chromosomal locus, on which the kinetochore structure is formed. The centromere/kinetochore is required for the equal separation of sister chromatids to daughter cells. Here, we review recent findings on centromere-specific chromatin, including its constitutive protein components, its de novo formation and maintenance mechanisms, and our progress in analyses with synthetic human artificial chromosomes (HACs).
Collapse
Affiliation(s)
- Junichirou Ohzeki
- Laboratory of Chromosome Engineering, Department of Frontier Research and Development, Kazusa DNA Research Institute, 2-6-7 Kazusa-Kamatari, Kisarazu 292-0818, Japan
| | - Vladimir Larionov
- Genome Structure and Function Group, Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - William C Earnshaw
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh EH9 3BF, UK
| | - Hiroshi Masumoto
- Laboratory of Chromosome Engineering, Department of Frontier Research and Development, Kazusa DNA Research Institute, 2-6-7 Kazusa-Kamatari, Kisarazu 292-0818, Japan.
| |
Collapse
|
28
|
Smurova K, De Wulf P. Centromere and Pericentromere Transcription: Roles and Regulation … in Sickness and in Health. Front Genet 2018; 9:674. [PMID: 30627137 PMCID: PMC6309819 DOI: 10.3389/fgene.2018.00674] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Accepted: 12/04/2018] [Indexed: 12/26/2022] Open
Abstract
The chromosomal loci known as centromeres (CEN) mediate the equal distribution of the duplicated genome between both daughter cells. Specifically, centromeres recruit a protein complex named the kinetochore, that bi-orients the replicated chromosome pairs to the mitotic or meiotic spindle structure. The paired chromosomes are then separated, and the individual chromosomes segregate in opposite direction along the regressing spindle into each daughter cell. Erroneous kinetochore assembly or activity produces aneuploid cells that contain an abnormal number of chromosomes. Aneuploidy may incite cell death, developmental defects (including genetic syndromes), and cancer (>90% of all cancer cells are aneuploid). While kinetochores and their activities have been preserved through evolution, the CEN DNA sequences have not. Hence, to be recognized as sites for kinetochore assembly, CEN display conserved structural themes. In addition, CEN nucleosomes enclose a CEN-exclusive variant of histone H3, named CENP-A, and carry distinct epigenetic labels on CENP-A and the other CEN histone proteins. Through the cell cycle, CEN are transcribed into non-coding RNAs. After subsequent processing, they become key components of the CEN chromatin by marking the CEN locus and by stably anchoring the CEN-binding kinetochore proteins. CEN transcription is tightly regulated, of low intensity, and essential for differentiation and development. Under- or overexpression of CEN transcripts, as documented for myriad cancers, provoke chromosome missegregation and aneuploidy. CEN are genetically stable and fully competent only when they are insulated from the surrounding, pericentromeric chromatin, which must be silenced. We will review CEN transcription and its contribution to faithful kinetochore function. We will further discuss how pericentromeric chromatin is silenced by RNA processing and transcriptionally repressive chromatin marks. We will report on the transcriptional misregulation of (peri)centromeres during stress, natural aging, and disease and reflect on whether their transcripts can serve as future diagnostic tools and anti-cancer targets in the clinic.
Collapse
Affiliation(s)
- Ksenia Smurova
- Centre for Integrative Biology, University of Trento, Trento, Italy
| | - Peter De Wulf
- Centre for Integrative Biology, University of Trento, Trento, Italy
| |
Collapse
|
29
|
Lu M, He X. Intricate regulation on epigenetic stability of the subtelomeric heterochromatin and the centromeric chromatin in fission yeast. Curr Genet 2018; 65:381-386. [PMID: 30244281 DOI: 10.1007/s00294-018-0886-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Revised: 09/12/2018] [Accepted: 09/14/2018] [Indexed: 01/30/2023]
Abstract
In eukaryotes, the integrity of chromatin structure and organization is crucial to diverse key cellular processes from development to disease avoidance. To maintain the cell identity through mitotic cell generations, the genome (the genomic DNA sequence) as well as the epigenome (pertaining various forms of epigenetic information carriers, such as histone modifications, nucleosome positioning and the chromatin organization) is inherited with high fidelity. In comparison to the wealth of knowledge on genetic stability, we know much less on what may control the accuracy of epigenetic inheritance. In our recent work in the fission yeast Schizosaccharomyces pombe, by quantifying the epigenetic fidelity of CENP-A/Cnp1 or H3K9me2 nucleosome inheritance through cell divisions, we demonstrated that Ccp1, a homolog of histone chaperone Vps75 in budding yeast, participates in the modulation of centromeric nucleosomal epigenetic stability as well as proper heterochromatin organization. In this essay, we focus on discussing the uniquely high dynamicity of the subtelomeric heterochromatin regions and the complex mechanisms regulating epigenetic stability of centromeric chromatin.
Collapse
Affiliation(s)
- Min Lu
- Life Sciences Institute and Innovation Center for Cell Signaling Network, Zhejiang University, Hangzhou, Zhejiang, 310058, China
| | - Xiangwei He
- Life Sciences Institute and Innovation Center for Cell Signaling Network, Zhejiang University, Hangzhou, Zhejiang, 310058, China.
| |
Collapse
|
30
|
Abstract
Accurate chromosome segregation is a fundamental process in cell biology. During mitosis, chromosomes are segregated into daughter cells through interactions between centromeres and microtubules in the mitotic spindle. Centromere domains have evolved to nucleate formation of the kinetochore, which is essential for establishing connections between chromosomal DNA and microtubules during mitosis. Centromeres are typically formed on highly repetitive DNA that is not conserved in sequence or size among organisms and can differ substantially between individuals within the same organism. However, transcription of repetitive DNA has emerged as a highly conserved property of the centromere. Recent work has shown that both the topological effect of transcription on chromatin and the nascent noncoding RNAs contribute to multiple aspects of centromere function. In this review, we discuss the fundamental aspects of centromere transcription, i.e., its dual role in chromatin remodeling/CENP-A deposition and kinetochore assembly during mitosis, from a cell cycle perspective.
Collapse
Affiliation(s)
- Carlos Perea-Resa
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts, USA
- Department of Genetics, Harvard Medical School, Boston, Massachusetts, USA
| | - Michael D Blower
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts, USA
- Department of Genetics, Harvard Medical School, Boston, Massachusetts, USA
| |
Collapse
|
31
|
Lu M, He X. Ccp1 modulates epigenetic stability at centromeres and affects heterochromatin distribution in Schizosaccharomyces pombe. J Biol Chem 2018; 293:12068-12080. [PMID: 29899117 PMCID: PMC6078436 DOI: 10.1074/jbc.ra118.003873] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Revised: 06/02/2018] [Indexed: 12/26/2022] Open
Abstract
Distinct chromatin organization features, such as centromeres and heterochromatin domains, are inherited epigenetically. However, the mechanisms that modulate the accuracy of epigenetic inheritance, especially at the individual nucleosome level, are not well-understood. Here, using ChIP and next-generation sequencing (ChIP-Seq), we characterized Ccp1, a homolog of the histone chaperone Vps75 in budding yeast that functions in centromere chromatin duplication and heterochromatin maintenance in fission yeast (Schizosaccharomyces pombe). We show that Ccp1 is enriched at the central core regions of the centromeres. Of note, among all histone chaperones characterized, deletion of the ccp1 gene uniquely reduced the rate of epigenetic switching, manifested as position effect variegation within the centromeric core region (CEN-PEV). In contrast, gene deletion of other histone chaperones either elevated the PEV switching rates or did not affect centromeric PEV. Ccp1 and the kinetochore components Mis6 and Sim4 were mutually dependent for centromere or kinetochore association at the proper levels. Moreover, Ccp1 influenced heterochromatin distribution at multiple loci in the genome, including the subtelomeric and the pericentromeric regions. We also found that Gar2, a protein predominantly enriched in the nucleolus, functions similarly to Ccp1 in modulating the epigenetic stability of centromeric regions, although its mechanism remained unclear. Together, our results identify Ccp1 as an important player in modulating epigenetic stability and maintaining proper organization of multiple chromatin domains throughout the fission yeast genome.
Collapse
Affiliation(s)
- Min Lu
- Life Sciences Institute and Innovation Center for Cell Signaling Network, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Xiangwei He
- Life Sciences Institute and Innovation Center for Cell Signaling Network, Zhejiang University, Hangzhou, Zhejiang 310058, China.
| |
Collapse
|
32
|
Abstract
Heterochromatin is a key architectural feature of eukaryotic chromosomes, which endows particular genomic domains with specific functional properties. The capacity of heterochromatin to restrain the activity of mobile elements, isolate DNA repair in repetitive regions and ensure accurate chromosome segregation is crucial for maintaining genomic stability. Nucleosomes at heterochromatin regions display histone post-translational modifications that contribute to developmental regulation by restricting lineage-specific gene expression. The mechanisms of heterochromatin establishment and of heterochromatin maintenance are separable and involve the ability of sequence-specific factors bound to nascent transcripts to recruit chromatin-modifying enzymes. Heterochromatin can spread along the chromatin from nucleation sites. The propensity of heterochromatin to promote its own spreading and inheritance is counteracted by inhibitory factors. Because of its importance for chromosome function, heterochromatin has key roles in the pathogenesis of various human diseases. In this Review, we discuss conserved principles of heterochromatin formation and function using selected examples from studies of a range of eukaryotes, from yeast to human, with an emphasis on insights obtained from unicellular model organisms.
Collapse
|
33
|
Chereji RV, Bharatula V, Elfving N, Blomberg J, Larsson M, Morozov AV, Broach JR, Björklund S. Mediator binds to boundaries of chromosomal interaction domains and to proteins involved in DNA looping, RNA metabolism, chromatin remodeling, and actin assembly. Nucleic Acids Res 2017; 45:8806-8821. [PMID: 28575439 PMCID: PMC5587782 DOI: 10.1093/nar/gkx491] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Accepted: 05/23/2017] [Indexed: 01/24/2023] Open
Abstract
Mediator is a multi-unit molecular complex that plays a key role in transferring signals from transcriptional regulators to RNA polymerase II in eukaryotes. We have combined biochemical purification of the Saccharomyces cerevisiae Mediator from chromatin with chromatin immunoprecipitation in order to reveal Mediator occupancy on DNA genome-wide, and to identify proteins interacting specifically with Mediator on the chromatin template. Tandem mass spectrometry of proteins in immunoprecipitates of mediator complexes revealed specific interactions between Mediator and the RSC, Arp2/Arp3, CPF, CF 1A and Lsm complexes in chromatin. These factors are primarily involved in chromatin remodeling, actin assembly, mRNA 3′-end processing, gene looping and mRNA decay, but they have also been shown to enter the nucleus and participate in Pol II transcription. Moreover, we have found that Mediator, in addition to binding Pol II promoters, occupies chromosomal interacting domain (CID) boundaries and that Mediator in chromatin associates with proteins that have been shown to interact with CID boundaries, such as Sth1, Ssu72 and histone H4. This suggests that Mediator plays a significant role in higher-order genome organization.
Collapse
Affiliation(s)
- Razvan V Chereji
- Division of Developmental Biology, Eunice Kennedy Shriver National Institute for Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Vasudha Bharatula
- Department of Biochemistry and Molecular Biology, Penn State College of Medicine, Hershey, PA 17033, USA
| | - Nils Elfving
- Department of Medical Biochemistry and Biophysics Umeå University, 901 87 Umeå, Sweden
| | - Jeanette Blomberg
- Department of Medical Biochemistry and Biophysics Umeå University, 901 87 Umeå, Sweden
| | - Miriam Larsson
- Department of Medical Biochemistry and Biophysics Umeå University, 901 87 Umeå, Sweden
| | - Alexandre V Morozov
- Department of Physics and Astronomy, Rutgers University, Piscataway, NJ 08854, USA.,Center for Quantitative Biology, Rutgers University, Piscataway, NJ 08854, USA
| | - James R Broach
- Department of Biochemistry and Molecular Biology, Penn State College of Medicine, Hershey, PA 17033, USA
| | - Stefan Björklund
- Department of Medical Biochemistry and Biophysics Umeå University, 901 87 Umeå, Sweden
| |
Collapse
|
34
|
Acharya S, Hartmann M, Erhardt S. Chromatin-associated noncoding RNAs in development and inheritance. WILEY INTERDISCIPLINARY REVIEWS-RNA 2017; 8. [PMID: 28840663 DOI: 10.1002/wrna.1435] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Revised: 06/30/2017] [Accepted: 07/03/2017] [Indexed: 12/13/2022]
Abstract
Noncoding RNAs (ncRNAs) have emerged as crucial players in chromatin regulation. Their diversity allows them to partake in the regulation of numerous cellular processes across species. During development, long and short ncRNAs act in conjunction with each other where long ncRNAs (lncRNAs) are best understood in establishing appropriate gene expression patterns, while short ncRNAs (sRNAs) are known to establish constitutive heterochromatin and suppress mobile elements. Additionally, increasing evidence demonstrates roles of sRNAs in several typically lncRNA-mediated processes such as dosage compensation, indicating a complex regulatory network of noncoding RNAs. Together, various ncRNAs establish many mitotically heritable epigenetic marks during development. Additionally, they participate in mechanisms that regulate maintenance of these epigenetic marks during the lifespan of the organism. Interestingly, some epigenetic traits are transmitted to the next generation(s) via paramutations or transgenerational inheritance mediated by sRNAs. In this review, we give an overview of the various functions and regulations of ncRNAs and the mechanisms they employ in the establishment and maintenance of epigenetic marks and multi-generational transmission of epigenetic traits. WIREs RNA 2017, 8:e1435. doi: 10.1002/wrna.1435 For further resources related to this article, please visit the WIREs website.
Collapse
Affiliation(s)
- Sreemukta Acharya
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, and CellNetworks, Im Neuenheimer Feld 282, Heidelberg, Germany
| | - Mark Hartmann
- Regulation of Cellular Differentiation Group, Division of Epigenomics and Cancer Risk Factors, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Sylvia Erhardt
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, and CellNetworks, Im Neuenheimer Feld 282, Heidelberg, Germany
| |
Collapse
|
35
|
Forsburg SL, Shen KF. Centromere Stability: The Replication Connection. Genes (Basel) 2017; 8:genes8010037. [PMID: 28106789 PMCID: PMC5295031 DOI: 10.3390/genes8010037] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Revised: 01/10/2017] [Accepted: 01/12/2017] [Indexed: 11/16/2022] Open
Abstract
The fission yeast centromere, which is similar to metazoan centromeres, contains highly repetitive pericentromere sequences that are assembled into heterochromatin. This is required for the recruitment of cohesin and proper chromosome segregation. Surprisingly, the pericentromere replicates early in the S phase. Loss of heterochromatin causes this domain to become very sensitive to replication fork defects, leading to gross chromosome rearrangements. This review examines the interplay between components of DNA replication, heterochromatin assembly, and cohesin dynamics that ensures maintenance of genome stability and proper chromosome segregation.
Collapse
Affiliation(s)
- Susan L Forsburg
- Program in Molecular & Computational Biology, University of Southern California, Los Angeles, CA 90089-2910, USA.
| | - Kuo-Fang Shen
- Program in Molecular & Computational Biology, University of Southern California, Los Angeles, CA 90089-2910, USA.
| |
Collapse
|
36
|
García Del Arco A, Erhardt S. Post-translational Modifications of Centromeric Chromatin. PROGRESS IN MOLECULAR AND SUBCELLULAR BIOLOGY 2017; 56:213-231. [PMID: 28840239 DOI: 10.1007/978-3-319-58592-5_9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Regulation of chromatin structures is important for the control of DNA processes such as gene expression, and misregulation of chromatin is implicated in diverse diseases. Covalent post-translational modifications of histones are a prominent way to regulate chromatin structure and different chromatin regions bear their specific signature of histone modifications. The composition of centromeric chromatin is significantly different from other chromatin structures and mainly defined by the presence of the histone H3-variant CENP-A. Here we summarize the composition of centromeric chromatin and what we know about its differential regulation by post-translational modifications.
Collapse
Affiliation(s)
- Ana García Del Arco
- Center for Molecular Biology of Heidelberg (ZMBH), DKFZ-ZMBH Alliance, Heidelberg University, Im Neuenheimer Feld 282, 69120, Heidelberg, Germany
| | - Sylvia Erhardt
- Center for Molecular Biology of Heidelberg (ZMBH), DKFZ-ZMBH Alliance, Heidelberg University, Im Neuenheimer Feld 282, 69120, Heidelberg, Germany.
- Cell Networks Excellence Cluster, Heidelberg University, Im Neuenheimer Feld 282, 69120, Heidelberg, Germany.
| |
Collapse
|
37
|
Dumont M, Fachinetti D. DNA Sequences in Centromere Formation and Function. PROGRESS IN MOLECULAR AND SUBCELLULAR BIOLOGY 2017; 56:305-336. [PMID: 28840243 DOI: 10.1007/978-3-319-58592-5_13] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Faithful chromosome segregation during cell division depends on the centromere, a complex DNA/protein structure that links chromosomes to spindle microtubules. This chromosomal domain has to be marked throughout cell division and its chromosomal localization preserved across cell generations. From fission yeast to human, centromeres are established on a series of repetitive DNA sequences and on specialized centromeric chromatin. This chromatin is enriched with the histone H3 variant, named CENP-A, that was demonstrated to be the epigenetic mark that maintains centromere identity and function indefinitely. Although centromere identity is thought to be exclusively epigenetic, the presence of specific DNA sequences in the majority of eukaryotes and of the centromeric protein CENP-B that binds to these sequences, suggests the existence of a genetic component as well. In this review, we will highlight the importance of centromeric sequences for centromere formation and function, and discuss the centromere DNA sequence/CENP-B paradox.
Collapse
Affiliation(s)
- M Dumont
- Institut Curie, PSL Research University, CNRS, UMR 144, 26 rue d'Ulm, 75005, Paris, France
| | - D Fachinetti
- Institut Curie, PSL Research University, CNRS, UMR 144, 26 rue d'Ulm, 75005, Paris, France.
| |
Collapse
|
38
|
Cam HP, Whitehall S. Analysis of Heterochromatin in Schizosaccharomyces pombe. Cold Spring Harb Protoc 2016; 2016:2016/11/pdb.top079889. [PMID: 27803258 DOI: 10.1101/pdb.top079889] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
This introduction briefly describes the biology of heterochromatin in the fission yeast Schizosaccharomyces pombe We highlight some of the salient features of fission yeast that render it an excellent unicellular eukaryote for studying heterochromatin. We then discuss key aspects of heterochromatin that are of interest to those in the field, and last we introduce experimental approaches often used to investigate heterochromatin.
Collapse
Affiliation(s)
- Hugh P Cam
- Biology Department, Boston College, Chestnut Hill, Massachusetts 02467
| | - Simon Whitehall
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle NE2 4HH, United Kingdom
| |
Collapse
|
39
|
Avva SVSP, Hart CM. Characterization of the Drosophila BEAF-32A and BEAF-32B Insulator Proteins. PLoS One 2016; 11:e0162906. [PMID: 27622635 PMCID: PMC5021357 DOI: 10.1371/journal.pone.0162906] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Accepted: 08/30/2016] [Indexed: 12/11/2022] Open
Abstract
Data implicate the Drosophila 32 kDa Boundary Element-Associated Factors BEAF-32A and BEAF-32B in both chromatin domain insulator element function and promoter function. They might also function as an epigenetic memory by remaining bound to mitotic chromosomes. Both proteins are made from the same gene. They differ in their N-terminal 80 amino acids, which contain single DNA-binding BED fingers. The remaining 200 amino acids are identical in the two proteins. The structure and function of the middle region of 120 amino acids is unknown, while the C-terminal region of 80 amino acids has a putative leucine zipper and a BESS domain and mediates BEAF-BEAF interactions. Here we report a further characterization of BEAF. We show that the BESS domain alone is sufficient to mediate BEAF-BEAF interactions, although the presence of the putative leucine zipper on at least one protein strengthens the interactions. BEAF-32B is sufficient to rescue a null BEAF mutation in flies. Using mutant BEAF-32B rescue transgenes, we show that the middle region and the BESS domain are essential. In contrast, the last 40 amino acids of the middle region, which is poorly conserved among Drosophila species, is dispensable. Deleting the putative leucine zipper results in a hypomorphic mutant BEAF-32B protein. Finally, we document the dynamics of BEAF-32A-EGFP and BEAF-32B-mRFP during mitosis in embryos. A subpopulation of both proteins appears to remain on mitotic chromosomes and also on the mitotic spindle, while much of the fluorescence is dispersed during mitosis. Differences in the dynamics of the two proteins are observed in syncytial embryos, and both proteins show differences between syncytial and later embryos. This characterization of BEAF lays a foundation for future studies into molecular mechanisms of BEAF function.
Collapse
Affiliation(s)
- S. V. Satya Prakash Avva
- Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana, United States of America
| | - Craig M. Hart
- Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana, United States of America
- * E-mail:
| |
Collapse
|
40
|
Identification of regulatory motifs in the CHO genome for stable monoclonal antibody production. Cytotechnology 2016; 69:451-460. [PMID: 27544513 DOI: 10.1007/s10616-016-0017-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Accepted: 08/08/2016] [Indexed: 01/05/2023] Open
Abstract
Chinese hamster ovary (CHO) cell lines are widely used for therapeutic protein production. When a transgene is integrated into the genome of a CHO cell, the expression level is highly dependent on the site of integration because of positional effects such as gene silencing. To overcome negative positional effects and establish stable CHO cell lines with high productivity, several regulatory DNA elements are used in vector construction. Previously, we established the CHO DR1000L-4N cell line, a stable and high copy number Dhfr gene-amplified cell line. It was hypothesized that the chromosomal location of the exogenous gene-amplified region in the CHO DR1000L-4N genome contains regulatory motifs for stable protein production. Therefore, we isolated DNA regulatory motifs from the CHO DR1000L-4N cell line and determined whether these motifs act as an insulator. Our results suggest that stable expression of a transgene can be promoted by the CHO genome sequence, and it would be a powerful tool for therapeutic protein manufacturing.
Collapse
|
41
|
Ohzeki JI, Shono N, Otake K, Martins NMC, Kugou K, Kimura H, Nagase T, Larionov V, Earnshaw WC, Masumoto H. KAT7/HBO1/MYST2 Regulates CENP-A Chromatin Assembly by Antagonizing Suv39h1-Mediated Centromere Inactivation. Dev Cell 2016; 37:413-27. [PMID: 27270040 PMCID: PMC4906249 DOI: 10.1016/j.devcel.2016.05.006] [Citation(s) in RCA: 71] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Revised: 04/08/2016] [Accepted: 05/09/2016] [Indexed: 01/01/2023]
Abstract
Centromere chromatin containing histone H3 variant CENP-A is required for accurate chromosome segregation as a foundation for kinetochore assembly. Human centromere chromatin assembles on a part of the long α-satellite (alphoid) DNA array, where it is flanked by pericentric heterochromatin. Heterochromatin spreads into adjacent chromatin and represses gene expression, and it can antagonize centromere function or CENP-A assembly. Here, we demonstrate an interaction between CENP-A assembly factor M18BP1 and acetyltransferase KAT7/HBO1/MYST2. Knocking out KAT7 in HeLa cells reduced centromeric CENP-A assembly. Mitotic chromosome misalignment and micronuclei formation increased in the knockout cells and were enhanced when the histone H3-K9 trimethylase Suv39h1 was overproduced. Tethering KAT7 to an ectopic alphoid DNA integration site removed heterochromatic H3K9me3 modification and was sufficient to stimulate new CENP-A or histone H3.3 assembly. Thus, KAT7-containing acetyltransferases associating with the Mis18 complex provides competence for histone turnover/exchange activity on alphoid DNA and prevents Suv39h1-mediated heterochromatin invasion into centromeres.
Collapse
Affiliation(s)
- Jun-Ichirou Ohzeki
- Laboratory of Cell Engineering, Department of Frontier Research, Kazusa DNA Research Institute, 2-6-7 Kazusa-Kamatari, Kisarazu 292-0818, Japan
| | - Nobuaki Shono
- Laboratory of Cell Engineering, Department of Frontier Research, Kazusa DNA Research Institute, 2-6-7 Kazusa-Kamatari, Kisarazu 292-0818, Japan
| | - Koichiro Otake
- Laboratory of Cell Engineering, Department of Frontier Research, Kazusa DNA Research Institute, 2-6-7 Kazusa-Kamatari, Kisarazu 292-0818, Japan
| | - Nuno M C Martins
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh EH9 3BF, UK
| | - Kazuto Kugou
- Laboratory of Cell Engineering, Department of Frontier Research, Kazusa DNA Research Institute, 2-6-7 Kazusa-Kamatari, Kisarazu 292-0818, Japan
| | - Hiroshi Kimura
- Department of Biological Sciences, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Yokohama 226-8501, Japan
| | - Takahiro Nagase
- Public Relations Team, Kazusa DNA Research Institute, Kisarazu 292-0818, Japan
| | - Vladimir Larionov
- Genome Structure and Function Group, Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - William C Earnshaw
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh EH9 3BF, UK
| | - Hiroshi Masumoto
- Laboratory of Cell Engineering, Department of Frontier Research, Kazusa DNA Research Institute, 2-6-7 Kazusa-Kamatari, Kisarazu 292-0818, Japan.
| |
Collapse
|
42
|
Rošić S, Erhardt S. No longer a nuisance: long non-coding RNAs join CENP-A in epigenetic centromere regulation. Cell Mol Life Sci 2016; 73:1387-98. [PMID: 26748759 PMCID: PMC11108473 DOI: 10.1007/s00018-015-2124-7] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Revised: 12/08/2015] [Accepted: 12/17/2015] [Indexed: 01/02/2023]
Abstract
Centromeres represent the basis for kinetochore formation, and are essential for proper chromosome segregation during mitosis. Despite these essential roles, centromeres are not defined by specific DNA sequences, but by epigenetic means. The histone variant CENP-A controls centromere identity epigenetically and is essential for recruiting kinetochore components that attach the chromosomes to the mitotic spindle during mitosis. Recently, a new player in centromere regulation has emerged: long non-coding RNAs transcribed from repetitive regions of centromeric DNA function in regulating centromeres epigenetically. This review summarizes recent findings on the essential roles that transcription, pericentromeric transcripts, and centromere-derived RNAs play in centromere biology.
Collapse
Affiliation(s)
- Silvana Rošić
- Medical Research Council Clinical Sciences Centre, Imperial College London, London, UK
| | - Sylvia Erhardt
- ZMBH, DKFZ-ZMBH-Alliance and CellNetworks Excellence Cluster, University of Heidelberg, Im Neuenheimer Feld 282, 69120, Heidelberg, Germany.
| |
Collapse
|
43
|
Verrier L, Taglini F, Barrales RR, Webb S, Urano T, Braun S, Bayne EH. Global regulation of heterochromatin spreading by Leo1. Open Biol 2016; 5:rsob.150045. [PMID: 25972440 PMCID: PMC4450266 DOI: 10.1098/rsob.150045] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Heterochromatin plays important roles in eukaryotic genome regulation. However, the repressive nature of heterochromatin combined with its propensity to self-propagate necessitates robust mechanisms to contain heterochromatin within defined boundaries and thus prevent silencing of expressed genes. Here we show that loss of the PAF complex (PAFc) component Leo1 compromises chromatin boundaries, resulting in invasion of heterochromatin into flanking euchromatin domains. Similar effects are seen upon deletion of other PAFc components, but not other factors with related functions in transcription-associated chromatin modification, indicating a specific role for PAFc in heterochromatin regulation. Loss of Leo1 results in reduced levels of H4K16 acetylation at boundary regions, while tethering of the H4K16 acetyltransferase Mst1 to boundary chromatin suppresses heterochromatin spreading in leo1Δ cells, suggesting that Leo1 antagonises heterochromatin spreading by promoting H4K16 acetylation. Our findings reveal a previously undescribed role for PAFc in regulating global heterochromatin distribution.
Collapse
Affiliation(s)
- Laure Verrier
- Institute of Cell Biology, University of Edinburgh, Edinburgh, UK
| | | | - Ramon R Barrales
- Butenandt Institute of Physiological Chemistry, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Shaun Webb
- Wellcome Trust Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, UK
| | - Takeshi Urano
- Department of Biochemistry, Faculty of Medicine, Shimane University, Izumo, Japan
| | - Sigurd Braun
- Butenandt Institute of Physiological Chemistry, Ludwig-Maximilians-Universität München, Munich, Germany
| | | |
Collapse
|
44
|
Ohzeki JI, Larionov V, Earnshaw WC, Masumoto H. Genetic and epigenetic regulation of centromeres: a look at HAC formation. Chromosome Res 2015; 23:87-103. [PMID: 25682171 DOI: 10.1007/s10577-015-9470-z] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The centromere is a specialized chromosomal locus required for accurate chromosome segregation. A specific histone H3 variant, CENP-A, assembles at centromeres. CENP-A is required for kinetochore protein assembly and is an epigenetic marker for the maintenance of a functional centromere. Human CENP-A chromatin normally assembles on α-satellite DNA (alphoid DNA), a centromeric repetitive sequence. Using alphoid DNA arrays, human artificial chromosomes (HACs) have been constructed in human HT1080 cells and used to dissect the requirements for CENP-A assembly on DNA sequence. However, centromere formation is not a simple genetic event. In other commonly used human cell lines, such as HeLa and U2OS cells, no functional de novo centromere formation occurs efficiently with the same centromeric alphoid DNA sequences. Recent studies using protein tethering combined with the HAC system and/or genetic manipulation have revealed that epigenetic chromatin regulation mechanisms are also involved in the CENP-A chromatin assembly pathway and subsequent centromere/kinetochore formation. We summarize the DNA sequence requirements for CENP-A assembly and discuss the epigenetic regulation of human centromeres.
Collapse
Affiliation(s)
- Jun-ichirou Ohzeki
- Laboratory of Cell Engineering, Department of Frontier Research, Kazusa DNA Research Institute, 2-6-7 Kazusa-Kamatari, Kisarazu, Chiba, 292-0818, Japan
| | | | | | | |
Collapse
|
45
|
Gal C, Murton HE, Subramanian L, Whale AJ, Moore KM, Paszkiewicz K, Codlin S, Bähler J, Creamer KM, Partridge JF, Allshire RC, Kent NA, Whitehall SK. Abo1, a conserved bromodomain AAA-ATPase, maintains global nucleosome occupancy and organisation. EMBO Rep 2015; 17:79-93. [PMID: 26582768 PMCID: PMC4718406 DOI: 10.15252/embr.201540476] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Accepted: 10/26/2015] [Indexed: 12/28/2022] Open
Abstract
Maintenance of the correct level and organisation of nucleosomes is crucial for genome function. Here, we uncover a role for a conserved bromodomain AAA‐ATPase, Abo1, in the maintenance of nucleosome architecture in fission yeast. Cells lacking abo1+ experience both a reduction and mis‐positioning of nucleosomes at transcribed sequences in addition to increased intragenic transcription, phenotypes that are hallmarks of defective chromatin re‐establishment behind RNA polymerase II. Abo1 is recruited to gene sequences and associates with histone H3 and the histone chaperone FACT. Furthermore, the distribution of Abo1 on chromatin is disturbed by impaired FACT function. The role of Abo1 extends to some promoters and also to silent heterochromatin. Abo1 is recruited to pericentromeric heterochromatin independently of the HP1 ortholog, Swi6, where it enforces proper nucleosome occupancy. Consequently, loss of Abo1 alleviates silencing and causes elevated chromosome mis‐segregation. We suggest that Abo1 provides a histone chaperone function that maintains nucleosome architecture genome‐wide.
Collapse
Affiliation(s)
- Csenge Gal
- Institute for Cell & Molecular Biosciences, Newcastle University, Newcastle, UK
| | - Heather E Murton
- Institute for Cell & Molecular Biosciences, Newcastle University, Newcastle, UK
| | - Lakxmi Subramanian
- Wellcome Trust Centre for Cell Biology & Institute of Cell Biology, University of Edinburgh, Edinburgh, UK
| | - Alex J Whale
- Institute for Cell & Molecular Biosciences, Newcastle University, Newcastle, UK
| | - Karen M Moore
- Biosciences, College of Life & Environmental Sciences, University of Exeter, Exeter, UK
| | - Konrad Paszkiewicz
- Biosciences, College of Life & Environmental Sciences, University of Exeter, Exeter, UK
| | - Sandra Codlin
- Department of Genetics, Evolution & Environment and UCL Cancer Institute, University College London, London, UK
| | - Jürg Bähler
- Department of Genetics, Evolution & Environment and UCL Cancer Institute, University College London, London, UK
| | - Kevin M Creamer
- Department of Pathology, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - Janet F Partridge
- Department of Pathology, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - Robin C Allshire
- Wellcome Trust Centre for Cell Biology & Institute of Cell Biology, University of Edinburgh, Edinburgh, UK
| | - Nicholas A Kent
- Cardiff School of Biosciences, Cardiff University, Cardiff, UK
| | - Simon K Whitehall
- Institute for Cell & Molecular Biosciences, Newcastle University, Newcastle, UK
| |
Collapse
|
46
|
Mizuguchi T, Barrowman J, Grewal SIS. Chromosome domain architecture and dynamic organization of the fission yeast genome. FEBS Lett 2015; 589:2975-86. [PMID: 26096785 PMCID: PMC4598268 DOI: 10.1016/j.febslet.2015.06.008] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2015] [Revised: 06/08/2015] [Accepted: 06/09/2015] [Indexed: 12/20/2022]
Abstract
Advanced techniques including the chromosome conformation capture (3C) methodology and its derivatives are complementing microscopy approaches to study genome organization, and are revealing new details of three-dimensional (3D) genome architecture at increasing resolution. The fission yeast Schizosaccharomyces pombe (S. pombe) comprises a small genome featuring organizational elements of more complex eukaryotic systems, including conserved heterochromatin assembly machinery. Here we review key insights into genome organization revealed in this model system through a variety of techniques. We discuss the predominant role of Rabl-like configuration for interphase chromosome organization and the dynamic changes that occur during mitosis and meiosis. High resolution Hi-C studies have also revealed the presence of locally crumpled chromatin regions called "globules" along chromosome arms, and implicated a critical role for pericentromeric heterochromatin in imposing fundamental constraints on the genome to maintain chromosome territoriality and stability. These findings have shed new light on the connections between genome organization and function. It is likely that insights gained from the S. pombe system will also broadly apply to higher eukaryotes.
Collapse
Affiliation(s)
- Takeshi Mizuguchi
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA.
| | - Jemima Barrowman
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Shiv I S Grewal
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| |
Collapse
|
47
|
Nwigwe IJ, Kim YJ, Wacker DA, Kim TH. Boundary Associated Long Noncoding RNA Mediates Long-Range Chromosomal Interactions. PLoS One 2015; 10:e0136104. [PMID: 26302455 PMCID: PMC4547746 DOI: 10.1371/journal.pone.0136104] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Accepted: 07/29/2015] [Indexed: 11/17/2022] Open
Abstract
CCCTC binding factor (CTCF) is involved in organizing chromosomes into mega base-sized, topologically associated domains (TADs) along with other factors that define sub-TAD organization. CTCF-Cohesin interactions have been shown to be critical for transcription insulation activity as it stabilizes long-range interactions to promote proper gene expression. Previous studies suggest that heterochromatin boundary activity of CTCF may be independent of Cohesin, and there may be additional mechanisms for defining topological domains. Here, we show that a boundary site we previously identified known as CTCF binding site 5 (CBS5) from the homeotic gene cluster A (HOXA) locus exhibits robust promoter activity. This promoter activity from the CBS5 boundary element generates a long noncoding RNA that we designate as boundary associated long noncoding RNA-1 (blncRNA1). Functional characterization of this RNA suggests that the transcript stabilizes long-range interactions at the HOXA locus and promotes proper expression of HOXA genes. Additionally, our functional analysis also shows that this RNA is not needed in the stabilization of CTCF-Cohesin interactions however CTCF-Cohesin interactions are critical in the transcription of blncRNA1. Thus, the CTCF-associated boundary element, CBS5, employs both Cohesin and noncoding RNA to establish and maintain topologically associated domains at the HOXA locus.
Collapse
Affiliation(s)
- Ifeoma Jane Nwigwe
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, CT, 06520, United States of America
| | - Yoon Jung Kim
- Center for Systems Biology and Department of Biological Sciences, The University of Texas at Dallas, Richardson, TX, 75080, United States of America
| | - David A. Wacker
- Departments of Internal and Emergency Medicine, University of Maryland School of Medicine, Baltimore, MD, 21201, United States of America
| | - Tae Hoon Kim
- Center for Systems Biology and Department of Biological Sciences, The University of Texas at Dallas, Richardson, TX, 75080, United States of America
| |
Collapse
|
48
|
Argonaute 2 Binds Directly to tRNA Genes and Promotes Gene Repression in cis. Mol Cell Biol 2015; 35:2278-94. [PMID: 25918241 DOI: 10.1128/mcb.00076-15] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
To further our understanding of the RNAi machinery within the human nucleus, we analyzed the chromatin and RNA binding of Argonaute 2 (AGO2) within human cancer cell lines. Our data indicated that AGO2 binds directly to nascent tRNA and 5S rRNA, and to the genomic loci from which these RNAs are transcribed, in a small RNA- and DICER-independent manner. AGO2 chromatin binding was not observed at non-TFIIIC-dependent RNA polymerase III (Pol III) genes or at extra-TFIIIC (ETC) sites, indicating that the interaction is specific for TFIIIC-dependent Pol III genes. A genome-wide analysis indicated that loss of AGO2 caused a global increase in mRNA expression level among genes that flank AGO2-bound tRNA genes. This effect was shown to be distinct from that of the disruption of DICER, DROSHA, or CTCF. We propose that AGO2 binding to tRNA genes has a novel and important regulatory role in human cells.
Collapse
|
49
|
Inner Kinetochore Protein Interactions with Regional Centromeres of Fission Yeast. Genetics 2015; 201:543-61. [PMID: 26275423 PMCID: PMC4596668 DOI: 10.1534/genetics.115.179788] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Accepted: 08/10/2015] [Indexed: 01/19/2023] Open
Abstract
Centromeres of the fission yeast Schizosaccharomyces pombe lack the highly repetitive sequences that make most other "regional" centromeres refractory to analysis. To map fission yeast centromeres, we applied H4S47C-anchored cleavage mapping and native and cross-linked chromatin immunoprecipitation with paired-end sequencing. H3 nucleosomes are nearly absent from the central domain, which is occupied by centromere-specific H3 (cenH3 or CENP-A) nucleosomes with two H4s per particle that are mostly unpositioned and are more widely spaced than nucleosomes elsewhere. Inner kinetochore proteins CENP-A, CENP-C, CENP-T, CENP-I, and Scm3 are highly enriched throughout the central domain except at tRNA genes, with no evidence for preferred kinetochore assembly sites. These proteins are weakly enriched and less stably incorporated in H3-rich heterochromatin. CENP-A nucleosomes protect less DNA from nuclease digestion than H3 nucleosomes, while CENP-T protects a range of fragment sizes. Our results suggest that CENP-T particles occupy linkers between CENP-A nucleosomes and that classical regional centromeres differ from other centromeres by the absence of CENP-A nucleosome positioning.
Collapse
|
50
|
Abstract
Insulators are regulatory elements that help to organize eukaryotic chromatin via enhancer-blocking and chromatin barrier activity. Although there are several examples of transposable element (TE)-derived insulators, the contribution of TEs to human insulators has not been systematically explored. Mammalian-wide interspersed repeats (MIRs) are a conserved family of TEs that have substantial regulatory capacity and share sequence characteristics with tRNA-related insulators. We sought to evaluate whether MIRs can serve as insulators in the human genome. We applied a bioinformatic screen using genome sequence and functional genomic data from CD4(+) T cells to identify a set of 1,178 predicted MIR insulators genome-wide. These predicted MIR insulators were computationally tested to serve as chromatin barriers and regulators of gene expression in CD4(+) T cells. The activity of predicted MIR insulators was experimentally validated using in vitro and in vivo enhancer-blocking assays. MIR insulators are enriched around genes of the T-cell receptor pathway and reside at T-cell-specific boundaries of repressive and active chromatin. A total of 58% of the MIR insulators predicted here show evidence of T-cell-specific chromatin barrier and gene regulatory activity. MIR insulators appear to be CCCTC-binding factor (CTCF) independent and show a distinct local chromatin environment with marked peaks for RNA Pol III and a number of histone modifications, suggesting that MIR insulators recruit transcriptional complexes and chromatin modifying enzymes in situ to help establish chromatin and regulatory domains in the human genome. The provisioning of insulators by MIRs across the human genome suggests a specific mechanism by which TE sequences can be used to modulate gene regulatory networks.
Collapse
|