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Shimada A, Cahn J, Ernst E, Lynn J, Grimanelli D, Henderson I, Kakutani T, Martienssen RA. Retrotransposon addiction promotes centromere function via epigenetically activated small RNAs. NATURE PLANTS 2024:10.1038/s41477-024-01773-1. [PMID: 39223305 DOI: 10.1038/s41477-024-01773-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Accepted: 07/26/2024] [Indexed: 09/04/2024]
Abstract
Retrotransposons have invaded eukaryotic centromeres in cycles of repeat expansion and purging, but the function of centromeric retrotransposons has remained unclear. In Arabidopsis, centromeric ATHILA retrotransposons give rise to epigenetically activated short interfering RNAs in mutants in DECREASE IN DNA METHYLATION1 (DDM1). Here we show that mutants that lose both DDM1 and RNA-dependent RNA polymerase have pleiotropic developmental defects and mis-segregate chromosome 5 during mitosis. Fertility and segregation defects are epigenetically inherited with centromere 5, and can be rescued by directing artificial small RNAs to ATHILA5 retrotransposons that interrupt tandem satellite repeats. Epigenetically activated short interfering RNAs promote pericentromeric condensation, chromosome cohesion and chromosome segregation in mitosis. We propose that insertion of ATHILA silences centromeric transcription, while simultaneously making centromere function dependent on retrotransposon small RNAs in the absence of DDM1. Parallels are made with the fission yeast Schizosaccharomyces pombe, where chromosome cohesion depends on RNA interference, and with humans, where chromosome segregation depends on both RNA interference and HELLSDDM1.
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Affiliation(s)
- Atsushi Shimada
- Howard Hughes Medical Institute, Cold Spring Harbor Laboratory, New York, NY, USA
| | - Jonathan Cahn
- Howard Hughes Medical Institute, Cold Spring Harbor Laboratory, New York, NY, USA
| | - Evan Ernst
- Howard Hughes Medical Institute, Cold Spring Harbor Laboratory, New York, NY, USA
| | - Jason Lynn
- Howard Hughes Medical Institute, Cold Spring Harbor Laboratory, New York, NY, USA
| | | | - Ian Henderson
- Department of Plant Sciences, Cambridge University, Cambridge, UK
| | | | - Robert A Martienssen
- Howard Hughes Medical Institute, Cold Spring Harbor Laboratory, New York, NY, USA.
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2
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Deng X, Yao Q, Horvath A, Jiang Z, Zhao J, Fischer T, Sugiyama T. The fission yeast ortholog of Coilin, Mug174, forms Cajal body-like nuclear condensates and is essential for cellular quiescence. Nucleic Acids Res 2024; 52:9174-9192. [PMID: 38828770 PMCID: PMC11347179 DOI: 10.1093/nar/gkae463] [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: 11/02/2023] [Revised: 05/08/2024] [Accepted: 05/16/2024] [Indexed: 06/05/2024] Open
Abstract
The Cajal body, a nuclear condensate, is crucial for ribonucleoprotein assembly, including small nuclear RNPs (snRNPs). While Coilin has been identified as an integral component of Cajal bodies, its exact function remains unclear. Moreover, no Coilin ortholog has been found in unicellular organisms to date. This study unveils Mug174 (Meiosis-upregulated gene 174) as the Coilin ortholog in the fission yeast Schizosaccharomyces pombe. Mug174 forms phase-separated condensates in vitro and is often associated with the nucleolus and the cleavage body in vivo. The generation of Mug174 foci relies on the trimethylguanosine (TMG) synthase Tgs1. Moreover, Mug174 interacts with Tgs1 and U snRNAs. Deletion of the mug174+ gene in S. pombe causes diverse pleiotropic phenotypes, encompassing defects in vegetative growth, meiosis, pre-mRNA splicing, TMG capping of U snRNAs, and chromosome segregation. In addition, we identified weak homology between Mug174 and human Coilin. Notably, human Coilin expressed in fission yeast colocalizes with Mug174. Critically, Mug174 is indispensable for the maintenance of and transition from cellular quiescence. These findings highlight the Coilin ortholog in fission yeast and suggest that the Cajal body is implicated in cellular quiescence, thereby preventing human diseases.
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Affiliation(s)
- Xiaoling Deng
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Qinglian Yao
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Attila Horvath
- The John Curtin School of Medical Research, The Australian National University, Canberra 2601, Australia
| | - Ziling Jiang
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Junjie Zhao
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Tamás Fischer
- The John Curtin School of Medical Research, The Australian National University, Canberra 2601, Australia
| | - Tomoyasu Sugiyama
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
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3
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Naish M, Henderson IR. The structure, function, and evolution of plant centromeres. Genome Res 2024; 34:161-178. [PMID: 38485193 PMCID: PMC10984392 DOI: 10.1101/gr.278409.123] [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] [Indexed: 03/22/2024]
Abstract
Centromeres are essential regions of eukaryotic chromosomes responsible for the formation of kinetochore complexes, which connect to spindle microtubules during cell division. Notably, although centromeres maintain a conserved function in chromosome segregation, the underlying DNA sequences are diverse both within and between species and are predominantly repetitive in nature. The repeat content of centromeres includes high-copy tandem repeats (satellites), and/or specific families of transposons. The functional region of the centromere is defined by loading of a specific histone 3 variant (CENH3), which nucleates the kinetochore and shows dynamic regulation. In many plants, the centromeres are composed of satellite repeat arrays that are densely DNA methylated and invaded by centrophilic retrotransposons. In some cases, the retrotransposons become the sites of CENH3 loading. We review the structure of plant centromeres, including monocentric, holocentric, and metapolycentric architectures, which vary in the number and distribution of kinetochore attachment sites along chromosomes. We discuss how variation in CENH3 loading can drive genome elimination during early cell divisions of plant embryogenesis. We review how epigenetic state may influence centromere identity and discuss evolutionary models that seek to explain the paradoxically rapid change of centromere sequences observed across species, including the potential roles of recombination. We outline putative modes of selection that could act within the centromeres, as well as the role of repeats in driving cycles of centromere evolution. Although our primary focus is on plant genomes, we draw comparisons with animal and fungal centromeres to derive a eukaryote-wide perspective of centromere structure and function.
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Affiliation(s)
- Matthew Naish
- Department of Plant Sciences, University of Cambridge, Cambridge CB2 3EA, United Kingdom
| | - Ian R Henderson
- Department of Plant Sciences, University of Cambridge, Cambridge CB2 3EA, United Kingdom
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Shimada A, Cahn J, Ernst E, Lynn J, Grimanelli D, Henderson I, Kakutani T, Martienssen RA. Retrotransposon addiction promotes centromere function via epigenetically activated small RNAs. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.02.551486. [PMID: 37577592 PMCID: PMC10418216 DOI: 10.1101/2023.08.02.551486] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/15/2023]
Abstract
Retrotransposons have invaded eukaryotic centromeres in cycles of repeat expansion and purging, but the function of centromeric retrotransposons, if any, has remained unclear. In Arabidopsis, centromeric ATHILA retrotransposons give rise to epigenetically activated short interfering RNAs (easiRNAs) in mutants in DECREASE IN DNA METHYLATION1 (DDM1), which promote histone H3 lysine-9 di-methylation (H3K9me2). Here, we show that mutants which lose both DDM1 and RNA dependent RNA polymerase (RdRP) have pleiotropic developmental defects and mis-segregation of chromosome 5 during mitosis. Fertility defects are epigenetically inherited with the centromeric region of chromosome 5, and can be rescued by directing artificial small RNAs to a single family of ATHILA5 retrotransposons specifically embedded within this centromeric region. easiRNAs and H3K9me2 promote pericentromeric condensation, chromosome cohesion and proper chromosome segregation in mitosis. Insertion of ATHILA silences transcription, while simultaneously making centromere function dependent on retrotransposon small RNAs, promoting the selfish survival and spread of centromeric retrotransposons. Parallels are made with the fission yeast S. pombe, where chromosome segregation depends on RNAi, and with humans, where chromosome segregation depends on both RNAi and HELLSDDM1.
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Affiliation(s)
- Atsushi Shimada
- Howard Hughes Medical Institute, Cold Spring Harbor Laboratory, 1 Bungtown Road, Cold Spring Harbor, New York 11724, USA
| | - Jonathan Cahn
- Howard Hughes Medical Institute, Cold Spring Harbor Laboratory, 1 Bungtown Road, Cold Spring Harbor, New York 11724, USA
| | - Evan Ernst
- Howard Hughes Medical Institute, Cold Spring Harbor Laboratory, 1 Bungtown Road, Cold Spring Harbor, New York 11724, USA
| | - Jason Lynn
- Howard Hughes Medical Institute, Cold Spring Harbor Laboratory, 1 Bungtown Road, Cold Spring Harbor, New York 11724, USA
| | - Daniel Grimanelli
- Epigenetic Regulations and Seed Development, UMR232, Institut de Recherche pour le Développement (IRD), Université de Montpellier, 34394 Montpellier, France
| | - Ian Henderson
- Department of Plant Sciences, Cambridge University, Cambridge UK
| | - Tetsuji Kakutani
- Faculty of Science, The University of Tokyo, Bunkyo-ku, Hongo, Tokyo 113-0033, Japan
| | - Robert A. Martienssen
- Howard Hughes Medical Institute, Cold Spring Harbor Laboratory, 1 Bungtown Road, Cold Spring Harbor, New York 11724, USA
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5
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Kelani AA, Bruch A, Rivieccio F, Visser C, Krüger T, Weaver D, Pan X, Schäuble S, Panagiotou G, Kniemeyer O, Bromley MJ, Bowyer P, Barber AE, Brakhage AA, Blango MG. Disruption of the Aspergillus fumigatus RNA interference machinery alters the conidial transcriptome. RNA (NEW YORK, N.Y.) 2023; 29:1033-1050. [PMID: 37019633 PMCID: PMC10275271 DOI: 10.1261/rna.079350.122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Accepted: 03/23/2023] [Indexed: 06/18/2023]
Abstract
The RNA interference (RNAi) pathway has evolved numerous functionalities in eukaryotes, with many on display in Kingdom Fungi. RNAi can regulate gene expression, facilitate drug resistance, or even be altogether lost to improve growth potential in some fungal pathogens. In the WHO fungal priority pathogen, Aspergillus fumigatus, the RNAi system is known to be intact and functional. To extend our limited understanding of A. fumigatus RNAi, we first investigated the genetic variation in RNAi-associated genes in a collection of 217 environmental and 83 clinical genomes, where we found that RNAi components are conserved even in clinical strains. Using endogenously expressed inverted-repeat transgenes complementary to a conditionally essential gene (pabA) or a nonessential gene (pksP), we determined that a subset of the RNAi componentry is active in inverted-repeat transgene silencing in conidia and mycelium. Analysis of mRNA-seq data from RNAi double-knockout strains linked the A. fumigatus dicer-like enzymes (DclA/B) and RNA-dependent RNA polymerases (RrpA/B) to regulation of conidial ribosome biogenesis genes; however, surprisingly few endogenous small RNAs were identified in conidia that could explain this broad change. Although RNAi was not clearly linked to growth or stress response defects in the RNAi knockouts, serial passaging of RNAi knockout strains for six generations resulted in lineages with diminished spore production over time, indicating that loss of RNAi can exert a fitness cost on the fungus. Cumulatively, A. fumigatus RNAi appears to play an active role in defense against double-stranded RNA species alongside a previously unappreciated housekeeping function in regulation of conidial ribosomal biogenesis genes.
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Affiliation(s)
- Abdulrahman A Kelani
- Junior Research Group RNA Biology of Fungal Infections, Leibniz Institute for Natural Product Research and Infection Biology-Hans Knöll Institute (Leibniz-HKI), 07745 Jena, Germany
| | - Alexander Bruch
- Junior Research Group RNA Biology of Fungal Infections, Leibniz Institute for Natural Product Research and Infection Biology-Hans Knöll Institute (Leibniz-HKI), 07745 Jena, Germany
| | - Flora Rivieccio
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology-Hans Knöll Institute (Leibniz-HKI), 07745 Jena, Germany
- Department of Microbiology and Molecular Biology, Institute of Microbiology, Friedrich Schiller University, 07743 Jena, Germany
| | - Corissa Visser
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology-Hans Knöll Institute (Leibniz-HKI), 07745 Jena, Germany
- Department of Microbiology and Molecular Biology, Institute of Microbiology, Friedrich Schiller University, 07743 Jena, Germany
| | - Thomas Krüger
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology-Hans Knöll Institute (Leibniz-HKI), 07745 Jena, Germany
| | - Danielle Weaver
- Manchester Fungal Infection Group, Division of Infection, Immunity and Respiratory Medicine, Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9NT, United Kingdom
| | - Xiaoqing Pan
- Junior Research Group RNA Biology of Fungal Infections, Leibniz Institute for Natural Product Research and Infection Biology-Hans Knöll Institute (Leibniz-HKI), 07745 Jena, Germany
| | - Sascha Schäuble
- Department of Microbiome Dynamics, Leibniz Institute for Natural Product Research and Infection Biology-Hans Knöll Institute (Leibniz-HKI), 07745 Jena, Germany
| | - Gianni Panagiotou
- Department of Microbiome Dynamics, Leibniz Institute for Natural Product Research and Infection Biology-Hans Knöll Institute (Leibniz-HKI), 07745 Jena, Germany
- Department of Medicine and State Key Laboratory of Pharmaceutical Biotechnology, University of Hong Kong, Hong Kong, China
| | - Olaf Kniemeyer
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology-Hans Knöll Institute (Leibniz-HKI), 07745 Jena, Germany
| | - Michael J Bromley
- Manchester Fungal Infection Group, Division of Infection, Immunity and Respiratory Medicine, Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9NT, United Kingdom
| | - Paul Bowyer
- Manchester Fungal Infection Group, Division of Infection, Immunity and Respiratory Medicine, Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9NT, United Kingdom
| | - Amelia E Barber
- Junior Research Group Fungal Informatics, Friedrich Schiller University, 07745 Jena, Germany
| | - Axel A Brakhage
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology-Hans Knöll Institute (Leibniz-HKI), 07745 Jena, Germany
- Department of Microbiology and Molecular Biology, Institute of Microbiology, Friedrich Schiller University, 07743 Jena, Germany
| | - Matthew G Blango
- Junior Research Group RNA Biology of Fungal Infections, Leibniz Institute for Natural Product Research and Infection Biology-Hans Knöll Institute (Leibniz-HKI), 07745 Jena, Germany
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6
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Kuzdere T, Flury V, Schalch T, Iesmantavicius V, Hess D, Bühler M. Differential phosphorylation of Clr4 SUV39H by Cdk1 accompanies a histone H3 methylation switch that is essential for gametogenesis. EMBO Rep 2022; 24:e55928. [PMID: 36408846 PMCID: PMC9827552 DOI: 10.15252/embr.202255928] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Revised: 10/18/2022] [Accepted: 10/27/2022] [Indexed: 11/22/2022] Open
Abstract
Methylation of histone H3 at lysine 9 (H3K9) is a hallmark of heterochromatin that plays crucial roles in gene silencing, genome stability, and chromosome segregation. In Schizosaccharomyces pombe, Clr4 mediates both di- and tri-methylation of H3K9. Although H3K9 methylation has been intensely studied in mitotic cells, its role during sexual differentiation remains unclear. Here, we map H3K9 methylation genome-wide during meiosis and show that constitutive heterochromatin temporarily loses H3K9me2 and becomes H3K9me3 when cells commit to meiosis. Cells lacking the ability to tri-methylate H3K9 exhibit meiotic chromosome segregation defects. Finally, the H3K9 methylation switch is accompanied by differential phosphorylation of Clr4 by the cyclin-dependent kinase Cdk1. Our results suggest that a conserved master regulator of the cell cycle controls the specificity of an H3K9 methyltransferase to prevent ectopic H3K9 methylation and to ensure faithful gametogenesis.
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Affiliation(s)
- Tahsin Kuzdere
- Friedrich Miescher Institute for Biomedical ResearchBaselSwitzerland,University of BaselBaselSwitzerland
| | - Valentin Flury
- Friedrich Miescher Institute for Biomedical ResearchBaselSwitzerland,University of BaselBaselSwitzerland
| | - Thomas Schalch
- Department of Molecular and Cell Biology, Leicester Institute of Structural and Chemical BiologyUniversity of LeicesterLeicesterUK
| | | | - Daniel Hess
- Friedrich Miescher Institute for Biomedical ResearchBaselSwitzerland
| | - Marc Bühler
- Friedrich Miescher Institute for Biomedical ResearchBaselSwitzerland,University of BaselBaselSwitzerland
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7
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Luo H, Wang J, Goes JI, Gomes HDR, Al-Hashmi K, Tobias C, Koerting C, Lin S. A grazing-driven positive nutrient feedback loop and active sexual reproduction underpin widespread Noctiluca green tides. ISME COMMUNICATIONS 2022; 2:103. [PMID: 37938758 PMCID: PMC9723592 DOI: 10.1038/s43705-022-00187-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Revised: 09/29/2022] [Accepted: 10/06/2022] [Indexed: 11/09/2023]
Abstract
The mixoplankton green Noctiluca scintillans (gNoctiluca) is known to form extensive green tides in tropical coastal ecosystems prone to eutrophication. In the Arabian Sea, their recent appearance and annual recurrence have upended an ecosystem that was once exclusively dominated by diatoms. Despite evidence of strong links to eutrophication, hypoxia and warming, the mechanisms underlying outbreaks of this mixoplanktonic dinoflagellate remain uncertain. Here we have used eco-physiological measurements and transcriptomic profiling to ascribe gNoctiluca's explosive growth during bloom formation to the form of sexual reproduction that produces numerous gametes. Rapid growth of gNoctiluca coincided with active ammonium and phosphate release from gNoctiluca cells, which exhibited high transcriptional activity of phagocytosis and metabolism generating ammonium. This grazing-driven nutrient flow ostensibly promotes the growth of phytoplankton as prey and offers positive support successively for bloom formation and maintenance. We also provide the first evidence that the host gNoctiluca cell could be manipulating growth of its endosymbiont population in order to exploit their photosynthetic products and meet critical energy needs. These findings illuminate gNoctiluca's little known nutritional and reproductive strategies that facilitate its ability to form intense and expansive gNoctiluca blooms to the detriment of regional water, food and the socio-economic security in several tropical countries.
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Affiliation(s)
- Hao Luo
- State Key Laboratory of Marine Environmental Science, College of the Environment and Ecology, and College of Ocean and Earth Sciences, Xiamen University, 361102, Xiamen, China
| | - Jingtian Wang
- State Key Laboratory of Marine Environmental Science, College of the Environment and Ecology, and College of Ocean and Earth Sciences, Xiamen University, 361102, Xiamen, China
| | - Joaquim I Goes
- Lamont-Doherty Earth Observatory at Columbia University, Palisades, NY, 10964, USA.
| | - Helga do R Gomes
- Lamont-Doherty Earth Observatory at Columbia University, Palisades, NY, 10964, USA
| | - Khalid Al-Hashmi
- Department of Marine Sciences and Fisheries, Sultan Qaboos University, Muscat, Oman
| | - Craig Tobias
- Department of Marine Sciences, University of Connecticut, Groton, CT, 06340, USA
| | - Claudia Koerting
- Department of Marine Sciences, University of Connecticut, Groton, CT, 06340, USA
| | - Senjie Lin
- State Key Laboratory of Marine Environmental Science, College of the Environment and Ecology, and College of Ocean and Earth Sciences, Xiamen University, 361102, Xiamen, China.
- Department of Marine Sciences, University of Connecticut, Groton, CT, 06340, USA.
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8
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Carro MDLM, Grimson A, Cohen PE. Small RNAs and their protein partners in animal meiosis. Curr Top Dev Biol 2022; 151:245-279. [PMID: 36681472 DOI: 10.1016/bs.ctdb.2022.06.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Meiosis is characterized by highly regulated transitions in gene expression that require diverse mechanisms of gene regulation. For example, in male mammals, transcription undergoes a global shut-down in early prophase I of meiosis, followed by increasing transcriptional activity into pachynema. Later, as spermiogenesis proceeds, the histones bound to DNA are replaced with transition proteins, which are themselves replaced with protamines, resulting in a highly condensed nucleus with repressed transcriptional activity. In addition, two specialized gene silencing events take place during prophase I: meiotic silencing of unsynapsed chromatin (MSUC), and the sex chromatin specific mechanism, meiotic sex chromosome inactivation (MSCI). Notably, conserved roles for the RNA binding protein (RBP) machinery that functions with small non-coding RNAs have been described as participating in these meiosis-specific mechanisms, suggesting that RNA-mediated gene regulation is critical for fertility in many species. Here, we review roles of small RNAs and their associated RBPs in meiosis-related processes such as centromere function, silencing of unpaired chromatin and meiotic recombination. We will discuss the emerging evidence of non-canonical functions of these components in meiosis.
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Affiliation(s)
- María de Las Mercedes Carro
- Department of Biomedical Sciences, Cornell University, Ithaca, NY, United States; Cornell Reproductive Sciences Center (CoRe), Cornell University, Ithaca, NY, United States
| | - Andrew Grimson
- Cornell Reproductive Sciences Center (CoRe), Cornell University, Ithaca, NY, United States; Department of Molecular Biology & Genetics, Cornell University, Ithaca, NY, United States.
| | - Paula E Cohen
- Department of Biomedical Sciences, Cornell University, Ithaca, NY, United States; Cornell Reproductive Sciences Center (CoRe), Cornell University, Ithaca, NY, United States.
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9
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Oliver C, Martinez G. Accumulation dynamics of ARGONAUTE proteins during meiosis in Arabidopsis. PLANT REPRODUCTION 2022; 35:153-160. [PMID: 34812935 PMCID: PMC9110482 DOI: 10.1007/s00497-021-00434-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Accepted: 11/12/2021] [Indexed: 06/13/2023]
Abstract
Meiosis is a specialized cell division that is key for reproduction and genetic diversity in sexually reproducing plants. Recently, different RNA silencing pathways have been proposed to carry a specific activity during meiosis, but the pathways involved during this process remain unclear. Here, we explored the subcellular localization of different ARGONAUTE (AGO) proteins, the main effectors of RNA silencing, during male meiosis in Arabidopsis thaliana using immunolocalizations with commercially available antibodies. We detected the presence of AGO proteins associated with posttranscriptional gene silencing (AGO1, 2, and 5) in the cytoplasm and the nucleus, while AGOs associated with transcriptional gene silencing (AGO4 and 9) localized exclusively in the nucleus. These results indicate that the localization of different AGOs correlates with their predicted roles at the transcriptional and posttranscriptional levels and provide an overview of their timing and potential role during meiosis.
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Affiliation(s)
- Cecilia Oliver
- Department of Plant Biology, Uppsala BioCenter, Swedish University of Agricultural, Sciences and Linnean Center for Plant Biology, Uppsala, Sweden.
| | - German Martinez
- Department of Plant Biology, Uppsala BioCenter, Swedish University of Agricultural, Sciences and Linnean Center for Plant Biology, Uppsala, Sweden.
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10
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The Cohesin Complex and Its Interplay with Non-Coding RNAs. Noncoding RNA 2021; 7:ncrna7040067. [PMID: 34707078 PMCID: PMC8552073 DOI: 10.3390/ncrna7040067] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 10/18/2021] [Accepted: 10/21/2021] [Indexed: 12/11/2022] Open
Abstract
The cohesin complex is a multi-subunit protein complex initially discovered for its role in sister chromatid cohesion. However, cohesin also has several other functions and plays important roles in transcriptional regulation, DNA double strand break repair, and chromosome architecture thereby influencing gene expression and development in organisms from yeast to man. While most of these functions rely on protein–protein interactions, post-translational protein, as well as DNA modifications, non-coding RNAs are emerging as additional players that facilitate and modulate the function or expression of cohesin and its individual components. This review provides a condensed overview about the architecture as well as the function of the cohesin complex and highlights its multifaceted interplay with both short and long non-coding RNAs.
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11
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Subtelomeric Chromatin in the Fission Yeast S. pombe. Microorganisms 2021; 9:microorganisms9091977. [PMID: 34576871 PMCID: PMC8466458 DOI: 10.3390/microorganisms9091977] [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: 08/10/2021] [Revised: 09/06/2021] [Accepted: 09/14/2021] [Indexed: 01/15/2023] Open
Abstract
Telomeres play important roles in safeguarding the genome. The specialized repressive chromatin that assembles at telomeres and subtelomeric domains is key to this protective role. However, in many organisms, the repetitive nature of telomeric and subtelomeric sequences has hindered research efforts. The fission yeast S. pombe has provided an important model system for dissection of chromatin biology due to the relative ease of genetic manipulation and strong conservation of important regulatory proteins with higher eukaryotes. Telomeres and the telomere-binding shelterin complex are highly conserved with mammals, as is the assembly of constitutive heterochromatin at subtelomeres. In this review, we seek to summarize recent work detailing the assembly of distinct chromatin structures within subtelomeric domains in fission yeast. These include the heterochromatic SH subtelomeric domains, the telomere-associated sequences (TAS), and ST chromatin domains that assemble highly condensed chromatin clusters called knobs. Specifically, we review new insights into the sequence of subtelomeric domains, the distinct types of chromatin that assemble on these sequences and how histone H3 K36 modifications influence these chromatin structures. We address the interplay between the subdomains of chromatin structure and how subtelomeric chromatin is influenced by both the telomere-bound shelterin complexes and by euchromatic chromatin regulators internal to the subtelomeric domain. Finally, we demonstrate that telomere clustering, which is mediated via the condensed ST chromatin knob domains, does not depend on knob assembly within these domains but on Set2, which mediates H3K36 methylation.
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12
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Onishi R, Yamanaka S, Siomi MC. piRNA- and siRNA-mediated transcriptional repression in Drosophila, mice, and yeast: new insights and biodiversity. EMBO Rep 2021; 22:e53062. [PMID: 34347367 PMCID: PMC8490990 DOI: 10.15252/embr.202153062] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 06/10/2021] [Accepted: 07/19/2021] [Indexed: 12/26/2022] Open
Abstract
The PIWI‐interacting RNA (piRNA) pathway acts as a self‐defense mechanism against transposons to maintain germline genome integrity. Failures in the piRNA pathway cause DNA damage in the germline genome, disturbing inheritance of “correct” genetic information by the next generations and leading to infertility. piRNAs execute transposon repression in two ways: degrading their RNA transcripts and compacting the genomic loci via heterochromatinization. The former event is mechanistically similar to siRNA‐mediated RNA cleavage that occurs in the cytoplasm and has been investigated in many species including nematodes, fruit flies, and mammals. The latter event seems to be mechanistically parallel to siRNA‐centered kinetochore assembly and subsequent chromosome segregation, which has so far been studied particularly in fission yeast. Despite the interspecies conservations, the overall schemes of the nuclear events show clear biodiversity across species. In this review, we summarize the recent progress regarding piRNA‐mediated transcriptional silencing in Drosophila and discuss the biodiversity by comparing it with the equivalent piRNA‐mediated system in mice and the siRNA‐mediated system in fission yeast.
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Affiliation(s)
- Ryo Onishi
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo, Japan
| | - Soichiro Yamanaka
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo, Japan
| | - Mikiko C Siomi
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo, Japan
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13
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Girard C, Budin K, Boisnard S, Zhang L, Debuchy R, Zickler D, Espagne E. RNAi-Related Dicer and Argonaute Proteins Play Critical Roles for Meiocyte Formation, Chromosome-Axes Lengths and Crossover Patterning in the Fungus Sordaria macrospora. Front Cell Dev Biol 2021; 9:684108. [PMID: 34262901 PMCID: PMC8274715 DOI: 10.3389/fcell.2021.684108] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Accepted: 06/01/2021] [Indexed: 11/29/2022] Open
Abstract
RNA interference (RNAi) is a cellular process involving small RNAs that target and regulate complementary RNA transcripts. This phenomenon has well-characterized roles in regulating gene and transposon expression. In addition, Dicer and Argonaute proteins, which are key players of RNAi, also have functions unrelated to gene repression. We show here that in the filamentous Ascomycete Sordaria macrospora, genes encoding the two Dicer (Dcl1 and Dcl2) and the two Argonaute (Sms2 and Qde2) proteins are dispensable for vegetative growth. However, we identified roles for all four proteins in the sexual cycle. Dcl1 and Sms2 are essential for timely and successful ascus/meiocyte formation. During meiosis per se, Dcl1, Dcl2, and Qde2 modulate, more or less severely, chromosome axis length and crossover numbers, patterning and interference. Additionally, Sms2 is necessary both for correct synaptonemal complex formation and loading of the pro-crossover E3 ligase-protein Hei10. Moreover, meiocyte formation, and thus meiotic induction, is completely blocked in the dcl1 dcl2 and dcl1 sms2 null double mutants. These results indicate complex roles of the RNAi machinery during major steps of the meiotic process with newly uncovered roles for chromosomes-axis length modulation and crossover patterning regulation.
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Affiliation(s)
- Chloe Girard
- Université Paris-Saclay, Commissariat à l'Énergie Atomiques et aux Énergies Alternatives (CEA), Centre National de la Recherche Scientifique (CNRS), Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France
| | - Karine Budin
- Université Paris-Saclay, Commissariat à l'Énergie Atomiques et aux Énergies Alternatives (CEA), Centre National de la Recherche Scientifique (CNRS), Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France
| | - Stéphanie Boisnard
- Université Paris-Saclay, Commissariat à l'Énergie Atomiques et aux Énergies Alternatives (CEA), Centre National de la Recherche Scientifique (CNRS), Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France
| | - Liangran Zhang
- Center for Reproductive Medicine, Cheeloo College of Medicine, Shandong University, Jinan, China
| | - Robert Debuchy
- Université Paris-Saclay, Commissariat à l'Énergie Atomiques et aux Énergies Alternatives (CEA), Centre National de la Recherche Scientifique (CNRS), Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France
| | - Denise Zickler
- Université Paris-Saclay, Commissariat à l'Énergie Atomiques et aux Énergies Alternatives (CEA), Centre National de la Recherche Scientifique (CNRS), Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France
| | - Eric Espagne
- Université Paris-Saclay, Commissariat à l'Énergie Atomiques et aux Énergies Alternatives (CEA), Centre National de la Recherche Scientifique (CNRS), Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France
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14
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Shan CM, Bao K, Diedrich J, Chen X, Lu C, Yates JR, Jia S. The INO80 Complex Regulates Epigenetic Inheritance of Heterochromatin. Cell Rep 2020; 33:108561. [PMID: 33378674 PMCID: PMC7896557 DOI: 10.1016/j.celrep.2020.108561] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 10/31/2020] [Accepted: 12/03/2020] [Indexed: 12/21/2022] Open
Abstract
One key aspect of epigenetic inheritance is that chromatin structures can be stably inherited through generations after the removal of the signals that establish such structures. In fission yeast, the RNA interference (RNAi) pathway is critical for the targeting of histone methyltransferase Clr4 to pericentric repeats to establish heterochromatin. However, pericentric heterochromatin cannot be properly inherited in the absence of RNAi, suggesting the existence of mechanisms that counteract chromatin structure inheritance. Here, we show that mutations of components of the INO80 chromatin-remodeling complex allow pericentric heterochromatin inheritance in RNAi mutants. The ability of INO80 to counter heterochromatin inheritance is attributed to one subunit, Iec5, which promotes histone turnover at heterochromatin but has little effects on nucleosome positioning at heterochromatin, gene expression, or the DNA damage response. These analyses demonstrate the importance of the INO80 chromatin-remodeling complex in controlling heterochromatin inheritance and maintaining the proper heterochromatin landscape of the genome.
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Affiliation(s)
- Chun-Min Shan
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA
| | - Kehan Bao
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA
| | - Jolene Diedrich
- Department of Chemical Physiology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Xiao Chen
- Department of Genetics and Development, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - Chao Lu
- Department of Genetics and Development, Columbia University Irving Medical Center, New York, NY 10032, USA; Herbert Irving Comprehensive Cancer Center, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - John R Yates
- Department of Chemical Physiology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Songtao Jia
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA.
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15
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Dai H, Gu W. Strategies and Best Practice in Cloning Small RNAs. GENE TECHNOLOGY 2020; 9:151. [PMID: 32953938 PMCID: PMC7500658] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
High-throughput sequencing has become a standard and powerful tool for analyzing nucleic acids primarily due to its sensitivity and convenience. Small RNAs play important roles in regulating cellular and viral genes. The conventional methods for small RNA analyses are tedious and often lack accuracy, specificity and sensitivity for many small RNA species. Therefore, high-throughput sequencing becomes an indispensable tool for analyzing small RNAs. However, it is challenging to generate a reliable and representative small RNA library for high-throughput sequencing since small RNAs are usually expressed at extremely low levels and often contain modifications which affect library construction, usually causing biased readouts. This review compares various strategies for generating small RNA libraries of high quality and reliability, and provides recommendations on best practice in preparing high-throughput sequencing RNA libraries.
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16
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Sun L, Liu XM, Li WZ, Yi YY, He X, Wang Y, Jin QW. The molecular chaperone Hsp90 regulates heterochromatin assembly through stabilizing multiple complexes in fission yeast. J Cell Sci 2020; 133:jcs244863. [PMID: 32499408 DOI: 10.1242/jcs.244863] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Accepted: 05/18/2020] [Indexed: 12/18/2022] Open
Abstract
In the fission yeast Schizosaccharomyces pombe, both RNAi machinery and RNAi-independent factors mediate transcriptional and posttranscriptional silencing and heterochromatin formation. Here, we show that the silencing of reporter genes at major native heterochromatic loci (centromeres, telomeres, mating-type locus and rDNA regions) and an artificially induced heterochromatin locus is alleviated in a fission yeast hsp90 mutant, hsp90-G84C Also, H3K9me2 enrichment at heterochromatin regions, especially at the mating-type locus and subtelomeres, is compromised, suggesting heterochromatin assembly defects. We further discovered that Hsp90 is required for stabilization or assembly of the RNA-induced transcriptional silencing (RITS) and Argonaute siRNA chaperone (ARC) RNAi effector complexes, the RNAi-independent factor Fft3, the shelterin complex subunit Poz1 and the Snf2/HDAC-containing repressor complex (SHREC). Our ChIP data suggest that Hsp90 regulates the efficient recruitment of the methyltransferase/ubiquitin ligase complex CLRC by shelterin to chromosome ends and targeting of the SHREC and Fft3 to mating type locus and/or rDNA region. Finally, our genetic analyses demonstrated that increased heterochromatin spreading restores silencing at subtelomeres in the hsp90-G84C mutant. Thus, this work uncovers a conserved factor critical for promoting RNAi-dependent and -independent heterochromatin assembly and gene silencing through stabilizing multiple effectors and effector complexes.
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Affiliation(s)
- Li Sun
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen 361102, Fujian, China
| | - Xiao-Min Liu
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen 361102, Fujian, China
| | - Wen-Zhu Li
- Life Sciences Institute and Innovation Center for Cell Signaling Network, Zhejiang University, Hangzhou 310058, Zhejiang, China
| | - Yuan-Yuan Yi
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen 361102, Fujian, China
| | - Xiangwei He
- Life Sciences Institute and Innovation Center for Cell Signaling Network, Zhejiang University, Hangzhou 310058, Zhejiang, China
| | - Yamei Wang
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen 361102, Fujian, China
| | - Quan-Wen Jin
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen 361102, Fujian, China
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17
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Farahani RM, Rezaei-Lotfi S, Hunter N. Genomic competition for noise reduction shaped evolutionary landscape of mir-4673. NPJ Syst Biol Appl 2020; 6:12. [PMID: 32376854 PMCID: PMC7203229 DOI: 10.1038/s41540-020-0131-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Accepted: 04/09/2020] [Indexed: 12/24/2022] Open
Abstract
The genomic platform that informs evolution of microRNA cascades remains unknown. Here we capitalised on the recent evolutionary trajectory of hominin-specific miRNA-4673, encoded in intron 4 of notch-1, to uncover the identity of one such precursor genomic element and the selective forces acting upon it. The miRNA targets genes that regulate Wnt/β-catenin signalling cascade. Primary sequence of the microRNA and its target region in Wnt modulating genes evolved from homologous signatures mapped to homotypic cis-clusters recognised by TCF3/4 and TFAP2A/B/C families. Integration of homologous TFAP2A/B/C cis-clusters (short range inhibitor of β-catenin) into the transcriptional landscape of Wnt cascade genes can reduce noise in gene expression. Probabilistic adoption of miRNA secondary structure by one such cis-signature in notch-1 reflected selection for superhelical curvature symmetry of precursor DNA to localise a nucleosome that overlapped the latter cis-cluster. By replicating the cis-cluster signature, non-random interactions of the miRNA with key Wnt modulator genes expanded the transcriptional noise buffering capacity via a coherent feed-forward loop mechanism. In consequence, an autonomous transcriptional noise dampener (the cis-cluster/nucleosome) evolved into a post-transcriptional one (the miRNA). The findings suggest a latent potential for remodelling of transcriptional landscape by miRNAs that capitalise on non-random distribution of genomic cis-signatures.
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Affiliation(s)
- Ramin M Farahani
- IDR/Westmead Institute for Medical Research and Westmead Centre for Oral Health, Sydney, NSW, Australia.
- Faculty of Medicine and Health Sciences, University of Sydney, Sydney, NSW, 2006, Australia.
| | - Saba Rezaei-Lotfi
- Faculty of Medicine and Health Sciences, University of Sydney, Sydney, NSW, 2006, Australia
| | - Neil Hunter
- IDR/Westmead Institute for Medical Research and Westmead Centre for Oral Health, Sydney, NSW, Australia
- Faculty of Medicine and Health Sciences, University of Sydney, Sydney, NSW, 2006, Australia
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18
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Gutbrod MJ, Martienssen RA. Conserved chromosomal functions of RNA interference. Nat Rev Genet 2020; 21:311-331. [PMID: 32051563 DOI: 10.1038/s41576-019-0203-6] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/26/2019] [Indexed: 12/21/2022]
Abstract
RNA interference (RNAi), a cellular process through which small RNAs target and regulate complementary RNA transcripts, has well-characterized roles in post-transcriptional gene regulation and transposon repression. Recent studies have revealed additional conserved roles for RNAi proteins, such as Argonaute and Dicer, in chromosome function. By guiding chromatin modification, RNAi components promote chromosome segregation during both mitosis and meiosis and regulate chromosomal and genomic dosage response. Small RNAs and the RNAi machinery also participate in the resolution of DNA damage. Interestingly, many of these lesser-studied functions seem to be more strongly conserved across eukaryotes than are well-characterized functions such as the processing of microRNAs. These findings have implications for the evolution of RNAi since the last eukaryotic common ancestor, and they provide a more complete view of the functions of RNAi.
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Affiliation(s)
- Michael J Gutbrod
- Watson School of Biological Sciences, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, USA
| | - Robert A Martienssen
- Watson School of Biological Sciences, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, USA. .,Howard Hughes Medical Institute, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, USA.
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19
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Bhattacharjee S, Roche B, Martienssen RA. RNA-induced initiation of transcriptional silencing (RITS) complex structure and function. RNA Biol 2019; 16:1133-1146. [PMID: 31213126 DOI: 10.1080/15476286.2019.1621624] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Heterochromatic regions of the genome are epigenetically regulated to maintain a heritable '"silent state"'. In fission yeast and other organisms, epigenetic silencing is guided by nascent transcripts, which are targeted by the RNA interference pathway. The key effector complex of the RNA interference pathway consists of small interfering RNA molecules (siRNAs) associated with Argonaute, assembled into the RNA-induced transcriptional silencing (RITS) complex. This review focuses on our current understanding of how RITS promotes heterochromatin formation, and in particular on the role of Argonaute-containing complexes in many other functions such as quelling, release of RNA polymerases, cellular quiescence and genome defense.
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Affiliation(s)
- Sonali Bhattacharjee
- a Cold Spring Harbor Laboratory, Howard Hughes Medical Institute , Cold Spring Harbor , NY , USA
| | - Benjamin Roche
- a Cold Spring Harbor Laboratory, Howard Hughes Medical Institute , Cold Spring Harbor , NY , USA
| | - Robert A Martienssen
- a Cold Spring Harbor Laboratory, Howard Hughes Medical Institute , Cold Spring Harbor , NY , USA
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20
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Nandi B, Talluri S, Kumar S, Yenumula C, Gold JS, Prabhala R, Munshi NC, Shammas MA. The roles of homologous recombination and the immune system in the genomic evolution of cancer. ACTA ACUST UNITED AC 2018; 5. [PMID: 30873294 PMCID: PMC6411307 DOI: 10.15761/jts.1000282] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
A variety of factors, whether extracellular (mutagens/carcinogens and viruses in the environment, chronic inflammation and radiation associated with the environment and/or electronic devices/machines) and/or intracellular (oxidative metabolites of food, oxidative stress due to inflammation, acid production, replication stress, DNA replication/repair errors, and certain hormones, cytokines, growth factors), pose a constant threat to the genomic integrity of a living cell. However, in the normal cellular environment multiple biological pathways including DNA repair, cell cycle, apoptosis and the immune system work in a precise, regulated (tightly controlled), timely and concerted manner to ensure genomic integrity, stability and proper functioning of a cell. If damage to DNA takes place, it is efficiently and accurately repaired by the DNA repair systems. Homologous recombination (HR) which utilizes either a homologous chromosome (in G1 phase) or a sister chromatid (in G2) as a template to repair the damage, is known to be the most precise repair system. HR in G2 which utilizes a sister chromatid as a template is also called an error free repair system. If DNA damage in a cell is so extensive that it overwhelms the repair system/s, the cell is eliminated by apoptosis. Thus, multiple pathways ensure that genome of a cell is intact and stable. However, constant exposure to DNA damage and/or dysregulation of DNA repair mechanism/s poses a risk of mutation and cancer. Oncogenesis, which seems to be a multistep process, is associated with acquisition of a number of genomic changes that enable a normal cell to progress from benign to malignant transformation. Transformed/cancer cells are recognized and killed by the immune system. However, the ongoing acquisition of new genomic changes enables cancer cells to survive/escape immune attack, evolve into a more aggressive phenotype, and eventually develop resistance to therapy. Although DNA repair (especially the HR) and the immune system play unique roles in preserving genomic integrity of a cell, they can also contribute to DNA damage, genomic instability and oncogenesis. The purpose of this article is to highlight the roles of DNA repair (especially HR) and the immune system in genomic evolution, with special focus on gastrointestinal cancer.
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Affiliation(s)
- B Nandi
- Harvard Medical School and Brigham and Women's Hospital, USA.,Researh Services, VA Healthcare System, West Roxbury, MA, USA
| | - S Talluri
- Harvard (Dana Farber) Cancer Institute, Boston, MA, USA.,Researh Services, VA Healthcare System, West Roxbury, MA, USA
| | - S Kumar
- Harvard (Dana Farber) Cancer Institute, Boston, MA, USA.,Harvard Medical School and Brigham and Women's Hospital, USA
| | - C Yenumula
- Harvard Medical School and Brigham and Women's Hospital, USA.,Researh Services, VA Healthcare System, West Roxbury, MA, USA
| | - J S Gold
- Harvard Medical School and Brigham and Women's Hospital, USA.,Surgery Services, VA Healthcare System, West Roxbury, MA, USA
| | - R Prabhala
- Harvard (Dana Farber) Cancer Institute, Boston, MA, USA.,Researh Services, VA Healthcare System, West Roxbury, MA, USA
| | - N C Munshi
- Harvard (Dana Farber) Cancer Institute, Boston, MA, USA.,Harvard Medical School and Brigham and Women's Hospital, USA.,Researh Services, VA Healthcare System, West Roxbury, MA, USA
| | - M A Shammas
- Harvard (Dana Farber) Cancer Institute, Boston, MA, USA.,Researh Services, VA Healthcare System, West Roxbury, MA, USA
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21
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Begnis M, Apte MS, Masuda H, Jain D, Wheeler DL, Cooper JP. RNAi drives nonreciprocal translocations at eroding chromosome ends to establish telomere-free linear chromosomes. Genes Dev 2018; 32:537-554. [PMID: 29654060 PMCID: PMC5959237 DOI: 10.1101/gad.311712.118] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Accepted: 03/29/2018] [Indexed: 12/19/2022]
Abstract
In this study, Begnis et al. show that HAATI, which is a mode of telomerase-minus survival in which canonical telomeres are superseded by blocks of nontelomeric rDNA heterochromatin that have spread to all chromosome ends, is formed and maintained. Their findings demonstrate that HAATI arises when telomere loss triggers a newly recognized illegitimate recombination pathway that requires RNAi factors, uncovering novel roles for ncRNAs in assembling a telomere-free chromosome end protection device. The identification of telomerase-negative HAATI (heterochromatin amplification-mediated and telomerase-independent) cells, in which telomeres are superseded by nontelomeric heterochromatin tracts, challenged the idea that canonical telomeres are essential for chromosome linearity and raised crucial questions as to how such tracts translocate to eroding chromosome ends and confer end protection. Here we show that HAATI arises when telomere loss triggers a newly recognized illegitimate translocation pathway that requires RNAi factors. While RNAi is necessary for the translocation events that mobilize ribosomal DNA (rDNA) tracts to all chromosome ends (forming “HAATIrDNA” chromosomes), it is dispensable for HAATIrDNA maintenance. Surprisingly, Dicer (Dcr1) plays a separate, RNAi-independent role in preventing formation of the rare HAATI subtype in which a different repetitive element (the subtelomeric element) replaces telomeres. Using genetics and fusions between shelterin components and rDNA-binding proteins, we mapped the mechanism by which rDNA loci engage crucial end protection factors—despite the absence of telomere repeats—and secure end protection. Sequence analysis of HAATIrDNA genomes allowed us to propose RNA and DNA polymerase template-switching models for the mechanism of RNAi-triggered rDNA translocations. Collectively, our results reveal unforeseen roles for noncoding RNAs (ncRNAs) in assembling a telomere-free chromosome end protection device.
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Affiliation(s)
- Martina Begnis
- Telomere Biology Section, Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA.,Telomere Biology Laboratory, Cancer Research UK, London Research Institute, London WC2A 3LY, United Kingdom
| | - Manasi S Apte
- Telomere Biology Section, Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Hirohisa Masuda
- Telomere Biology Section, Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Devanshi Jain
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA
| | - David Lee Wheeler
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Julia Promisel Cooper
- Telomere Biology Section, Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA.,Telomere Biology Laboratory, Cancer Research UK, London Research Institute, London WC2A 3LY, United Kingdom
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22
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RNA-Interference Pathways Display High Rates of Adaptive Protein Evolution in Multiple Invertebrates. Genetics 2018; 208:1585-1599. [PMID: 29437826 PMCID: PMC5887150 DOI: 10.1534/genetics.117.300567] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Accepted: 01/31/2018] [Indexed: 12/30/2022] Open
Abstract
Conflict between organisms can lead to a reciprocal adaptation that manifests as an increased evolutionary rate in genes mediating the conflict. This adaptive signature has been observed in RNA-interference (RNAi) pathway genes involved in the suppression of viruses and transposable elements in Drosophila melanogaster, suggesting that a subset of Drosophila RNAi genes may be locked in an arms race with these parasites. However, it is not known whether rapid evolution of RNAi genes is a general phenomenon across invertebrates, or which RNAi genes generally evolve adaptively. Here we use population genomic data from eight invertebrate species to infer rates of adaptive sequence evolution, and to test for past and ongoing selective sweeps in RNAi genes. We assess rates of adaptive protein evolution across species using a formal meta-analytic framework to combine data across species and by implementing a multispecies generalized linear mixed model of mutation counts. Across species, we find that RNAi genes display a greater rate of adaptive protein substitution than other genes, and that this is primarily mediated by positive selection acting on the genes most likely to defend against viruses and transposable elements. In contrast, evidence for recent selective sweeps is broadly spread across functional classes of RNAi genes and differs substantially among species. Finally, we identify genes that exhibit elevated adaptive evolution across the analyzed insect species, perhaps due to concurrent parasite-mediated arms races.
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23
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Raman V, Simon SA, Demirci F, Nakano M, Meyers BC, Donofrio NM. Small RNA Functions Are Required for Growth and Development of Magnaporthe oryzae. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2017; 30:517-530. [PMID: 28504560 DOI: 10.1094/mpmi-11-16-0236-r] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
RNA interference (RNAi) is conserved in eukaryotic organisms, and it has been well studied in many animal and plant species and some fungal species, yet it is not well studied in fungal plant pathogens. In the rice blast fungus Magnaporthe oryzae, we examined small RNA (sRNA) and their biogenesis in the context of growth and pathogenicity. Through genetic and genomic analyses, we demonstrate that loss of a single gene encoding Dicer, RNA-dependent RNA polymerase, or Argonaute reduces sRNA levels. These three proteins are required for the biogenesis of sRNA-matching genome-wide regions (coding regions, repeats, and intergenic regions). The loss of one Argonaute reduced both sRNA and fungal virulence on barley leaves. Transcriptome analysis of multiple mutants revealed that sRNA play an important role in transcriptional regulation of repeats and intergenic regions in M. oryzae. Together, these data support that M. oryzae sRNA regulate developmental processes including, fungal growth and virulence.
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Affiliation(s)
- Vidhyavathi Raman
- 1 Department of Plant & Soil Sciences, University of Delaware, Newark 19716, U.S.A.; and
| | - Stacey A Simon
- 1 Department of Plant & Soil Sciences, University of Delaware, Newark 19716, U.S.A.; and
- 2 Delaware Biotechnology Institute, University of Delaware, Newark 19711, U.S.A
| | - Feray Demirci
- 1 Department of Plant & Soil Sciences, University of Delaware, Newark 19716, U.S.A.; and
- 2 Delaware Biotechnology Institute, University of Delaware, Newark 19711, U.S.A
| | - Mayumi Nakano
- 1 Department of Plant & Soil Sciences, University of Delaware, Newark 19716, U.S.A.; and
- 2 Delaware Biotechnology Institute, University of Delaware, Newark 19711, U.S.A
| | - Blake C Meyers
- 1 Department of Plant & Soil Sciences, University of Delaware, Newark 19716, U.S.A.; and
- 2 Delaware Biotechnology Institute, University of Delaware, Newark 19711, U.S.A
| | - Nicole M Donofrio
- 1 Department of Plant & Soil Sciences, University of Delaware, Newark 19716, U.S.A.; and
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24
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Abstract
Most cells in nature are not actively dividing, yet are able to return to the cell cycle given the appropriate environmental signals. There is now ample evidence that quiescent G0 cells are not shut-down but still metabolically and transcriptionally active. Quiescent cells must maintain a basal transcriptional capacity to maintain transcripts and proteins necessary for survival. This implies a tight control over RNA polymerases: RNA pol II for mRNA transcription during G0, but especially RNA pol I and RNA pol III to maintain an appropriate level of structural RNAs, raising the possibility that specific transcriptional control mechanisms evolved in quiescent cells. In accordance with this, we recently discovered that RNA interference is necessary to control RNA polymerase I transcription during G0. While this mini-review focuses on yeast model organisms (Saccharomyces cerevisiae and Schizosaccharomyces pombe), parallels are drawn to other eukaryotes and mammalian systems, in particular stem cells.
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Affiliation(s)
- Benjamin Roche
- a Cold Spring Harbor Laboratory , Cold Spring Harbor , NY , USA
| | - Benoit Arcangioli
- b Genome Dynamics Unit , UMR 3525 CNRS, Institut Pasteur, 25-28 rue du Docteur Roux , Paris , France
| | - Robert Martienssen
- a Cold Spring Harbor Laboratory , Cold Spring Harbor , NY , USA.,c Howard Hughes Medical Institute-Gordon and Betty Moore Foundation (HHMI-GBM) Investigator , NY , USA
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25
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The emerging role of RNAs in DNA damage repair. Cell Death Differ 2017; 24:580-587. [PMID: 28234355 PMCID: PMC5384027 DOI: 10.1038/cdd.2017.16] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Revised: 01/16/2017] [Accepted: 01/23/2017] [Indexed: 12/25/2022] Open
Abstract
Many surveillance and repair mechanisms exist to maintain the integrity of our genome. All of the pathways described to date are controlled exclusively by proteins, which through their enzymatic activities identify breaks, propagate the damage signal, recruit further protein factors and ultimately resolve the break with little to no loss of genetic information. RNA is known to have an integral role in many cellular pathways, but, until very recently, was not considered to take part in the DNA repair process. Several reports demonstrated a conserved critical role for RNA-processing enzymes and RNA molecules in DNA repair, but the biogenesis of these damage-related RNAs and their mechanisms of action remain unknown. We will explore how these new findings challenge the idea of proteins being the sole participants in the response to DNA damage and reveal a new and exciting aspect of both DNA repair and RNA biology.
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26
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Folco HD, Chalamcharla VR, Sugiyama T, Thillainadesan G, Zofall M, Balachandran V, Dhakshnamoorthy J, Mizuguchi T, Grewal SIS. Untimely expression of gametogenic genes in vegetative cells causes uniparental disomy. Nature 2017; 543:126-130. [PMID: 28199302 PMCID: PMC5567995 DOI: 10.1038/nature21372] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Accepted: 12/28/2016] [Indexed: 01/03/2023]
Affiliation(s)
- H Diego Folco
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Venkata R Chalamcharla
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Tomoyasu Sugiyama
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Gobi Thillainadesan
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Martin Zofall
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Vanivilasini Balachandran
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Jothy Dhakshnamoorthy
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Takeshi Mizuguchi
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Shiv I S Grewal
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
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Braun S, Barrales RR. Beyond Tethering and the LEM domain: MSCellaneous functions of the inner nuclear membrane Lem2. Nucleus 2016; 7:523-531. [PMID: 27797637 DOI: 10.1080/19491034.2016.1252892] [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] [Indexed: 01/21/2023] Open
Abstract
The nuclear envelope plays a pivotal role in the functional organization of chromatin. Various inner nuclear membrane (INM) proteins associate with transcriptionally repressed chromatin, which is often found at the nuclear periphery. A prominent example is the conserved family of LEM (LAP2-Emerin-MAN1) domain proteins that interact with DNA-binding proteins and have been proposed to mediate tethering of chromatin to the nuclear membrane. We recently reported that the fission yeast protein Lem2, a homolog of metazoan LEM proteins, contributes to perinuclear localization and silencing of heterochromatin. 1 We demonstrate that binding and tethering of centromeric chromatin depends on the LEM domain of Lem2. Unexpectedly, this domain is dispensable for heterochromatin silencing, which is instead mediated by a different structural domain of Lem2, the MSC (MAN1-Src1 C-terminal) domain. Hence, silencing and tethering by Lem2 can be mechanistically separated. Notably, the MSC domain has multiple functions beyond heterochromatic silencing. Here we discuss the implications of these novel findings for the understanding of this conserved INM protein.
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Affiliation(s)
- Sigurd Braun
- a Department of Physiological Chemistry , Biomedical Center (BMC), Ludwig-Maximilians-University of Munich , Martinsried , Germany
| | - Ramón Ramos Barrales
- a Department of Physiological Chemistry , Biomedical Center (BMC), Ludwig-Maximilians-University of Munich , Martinsried , Germany.,b Present address: Centro Andaluz de Biología del Desarrollo. Universidad Pablo de Olavide, Sevilla-CSIC-Junta de Andalucía , Sevilla , Spain
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28
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Roche B, Arcangioli B, Martienssen RA. RNA interference is essential for cellular quiescence. Science 2016; 354:science.aah5651. [PMID: 27738016 DOI: 10.1126/science.aah5651] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2016] [Accepted: 09/27/2016] [Indexed: 12/19/2022]
Abstract
Quiescent cells play a predominant role in most organisms. Here we identify RNA interference (RNAi) as a major requirement for quiescence (G0 phase of the cell cycle) in Schizosaccharomyces pombe RNAi mutants lose viability at G0 entry and are unable to maintain long-term quiescence. We identified suppressors of G0 defects in cells lacking Dicer (dcr1Δ), which mapped to genes involved in chromosome segregation, RNA polymerase-associated factors, and heterochromatin formation. We propose a model in which RNAi promotes the release of RNA polymerase in cycling and quiescent cells: (i) RNA polymerase II release mediates heterochromatin formation at centromeres, allowing proper chromosome segregation during mitotic growth and G0 entry, and (ii) RNA polymerase I release prevents heterochromatin formation at ribosomal DNA during quiescence maintenance. Our model may account for the codependency of RNAi and histone H3 lysine 9 methylation throughout eukaryotic evolution.
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Affiliation(s)
- B Roche
- Howard Hughes Medical Institute-Gordon and Betty Moore Foundation, Cold Spring Harbor Laboratory, 1 Bungtown Road, Cold Spring Harbor, NY 11724, USA
| | - B Arcangioli
- Dynamics of the Genome Unit, Department of Genomes and Genetics, Institut Pasteur, UMR3525, 25-28 rue du Docteur Roux, Paris 75015, France
| | - R A Martienssen
- Howard Hughes Medical Institute-Gordon and Betty Moore Foundation, Cold Spring Harbor Laboratory, 1 Bungtown Road, Cold Spring Harbor, NY 11724, USA.
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29
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Bhardwaj S, Schlackow M, Rabajdova M, Gullerova M. Transcription facilitates sister chromatid cohesion on chromosomal arms. Nucleic Acids Res 2016; 44:6676-92. [PMID: 27084937 PMCID: PMC5001582 DOI: 10.1093/nar/gkw252] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Cohesin is a multi-subunit protein complex essential for sister chromatid cohesion, gene expression and DNA damage repair. Although structurally well studied, the underlying determinant of cohesion establishment on chromosomal arms remains enigmatic. Here, we show two populations of functionally distinct cohesin on chromosomal arms using a combination of genomics and single-locus specific DNA-FISH analysis. Chromatin bound cohesin at the loading sites co-localizes with Pds5 and Eso1 resulting in stable cohesion. In contrast, cohesin independent of its loader is unable to maintain cohesion and associates with chromatin in a dynamic manner. Cohesive sites coincide with highly expressed genes and transcription inhibition leads to destabilization of cohesin on chromatin. Furthermore, induction of transcription results in de novo recruitment of cohesive cohesin. Our data suggest that transcription facilitates cohesin loading onto chromosomal arms and is a key determinant of cohesive sites in fission yeast.
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Affiliation(s)
- Shweta Bhardwaj
- Sir William Dunn School of Pathology, South Parks Road, Oxford OX1 3RE, UK
| | | | | | - Monika Gullerova
- Sir William Dunn School of Pathology, South Parks Road, Oxford OX1 3RE, UK
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30
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Armas-Tizapantzi A, Montiel-González AM. RNAi silencing: A tool for functional genomics research on fungi. FUNGAL BIOL REV 2016. [DOI: 10.1016/j.fbr.2016.05.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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31
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The Dicer-like, Argonaute and RNA-dependent RNA polymerase gene families in Populus trichocarpa: gene structure, gene expression, phylogenetic analysis and evolution. J Genet 2016; 94:317-21. [PMID: 26174682 DOI: 10.1007/s12041-015-0508-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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32
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Tucker JF, Ohle C, Schermann G, Bendrin K, Zhang W, Fischer T, Zhang K. A Novel Epigenetic Silencing Pathway Involving the Highly Conserved 5'-3' Exoribonuclease Dhp1/Rat1/Xrn2 in Schizosaccharomyces pombe. PLoS Genet 2016; 12:e1005873. [PMID: 26889830 PMCID: PMC4758730 DOI: 10.1371/journal.pgen.1005873] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Accepted: 01/26/2016] [Indexed: 01/09/2023] Open
Abstract
Epigenetic gene silencing plays a critical role in regulating gene expression and contributes to organismal development and cell fate acquisition in eukaryotes. In fission yeast, Schizosaccharomyces pombe, heterochromatin-associated gene silencing is known to be mediated by RNA processing pathways including RNA interference (RNAi) and a 3’-5’ exoribonuclease complex, the exosome. Here, we report a new RNA-processing pathway that contributes to epigenetic gene silencing and assembly of heterochromatin mediated by 5’-3’ exoribonuclease Dhp1/Rat1/Xrn2. Dhp1 mutation causes defective gene silencing both at peri-centromeric regions and at the silent mating type locus. Intriguingly, mutation in either of the two well-characterized Dhp1-interacting proteins, the Din1 pyrophosphohydrolase or the Rhn1 transcription termination factor, does not result in silencing defects at the main heterochromatic regions. We demonstrate that Dhp1 interacts with heterochromatic factors and is essential in the sequential steps of establishing silencing in a manner independent of both RNAi and the exosome. Genomic and genetic analyses suggest that Dhp1 is involved in post-transcriptional silencing of repetitive regions through its RNA processing activity. The results describe the unexpected role of Dhp1/Rat1/Xrn2 in chromatin-based silencing and elucidate how various RNA-processing pathways, acting together or independently, contribute to epigenetic regulation of the eukaryotic genome. Epigenetic mechanisms regulate when, where, and how an organism uses the genetic information stored in its genome. They are essential to many cellular processes, such as the regulation of gene expression, genome organization, and cell-fate determination. They also govern growth, development, and ultimately human health. Heterochromatin constitutes silenced chromatic domains, in which gene silencing occurs through epigenetic mechanisms. RNA processing pathways, such as RNA interference (RNAi) and the exosome, are known to mediate the silencing of genes via degradation of unwanted or aberrant transcripts. In this study, we describe a new RNA processing mechanism in epigenetic silencing using fission yeast, a premier model for studying these processes. With genetic, cell biology, and genomic approaches, we uncovered a previously unrecognized function of Dhp1, a highly conserved 5’-3’ exoribonuclease and ortholog of budding yeast Rat1 and metazoan Xrn2. We show that Dhp1 mediates a novel RNA processing mechanism in epigenetic silencing which occurs independently of both RNAi and the exosome. Our results clarify how multiple RNA processing pathways are involved in the regulation of eukaryotic gene expression and chromatin organization.
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Affiliation(s)
- James Franklin Tucker
- Department of Biology, Wake Forest University, Winston-Salem, North Carolina, United States of America
| | - Corina Ohle
- Biochemistry Center (BZH), Heidelberg University, Heidelberg, Germany
| | - Géza Schermann
- Biochemistry Center (BZH), Heidelberg University, Heidelberg, Germany
| | - Katja Bendrin
- Biochemistry Center (BZH), Heidelberg University, Heidelberg, Germany
| | - Wei Zhang
- Department of Microbiology-Immunology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - Tamás Fischer
- Biochemistry Center (BZH), Heidelberg University, Heidelberg, Germany
| | - Ke Zhang
- Department of Biology, Wake Forest University, Winston-Salem, North Carolina, United States of America
- * E-mail:
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Termolino P, Cremona G, Consiglio MF, Conicella C. Insights into epigenetic landscape of recombination-free regions. Chromosoma 2016; 125:301-8. [PMID: 26801812 PMCID: PMC4830869 DOI: 10.1007/s00412-016-0574-9] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2015] [Revised: 01/10/2016] [Accepted: 01/12/2016] [Indexed: 11/29/2022]
Abstract
Genome architecture is shaped by gene-rich and repeat-rich regions also known as euchromatin and heterochromatin, respectively. Under normal conditions, the repeat-containing regions undergo little or no meiotic crossover (CO) recombination. COs within repeats are risky for the genome integrity. Indeed, they can promote non-allelic homologous recombination (NAHR) resulting in deleterious genomic rearrangements associated with diseases in humans. The assembly of heterochromatin is driven by the combinatorial action of many factors including histones, their modifications, and DNA methylation. In this review, we discuss current knowledge dealing with the epigenetic signatures of the major repeat regions where COs are suppressed. Then we describe mutants for epiregulators of heterochromatin in different organisms to find out how chromatin structure influences the CO rate and distribution.
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Affiliation(s)
- Pasquale Termolino
- CNR, National Research Council of Italy, Institute of Biosciences and Bioresources, Research Division Portici, Via Università 133, 80055, Portici, Italy
| | - Gaetana Cremona
- CNR, National Research Council of Italy, Institute of Biosciences and Bioresources, Research Division Portici, Via Università 133, 80055, Portici, Italy
| | - Maria Federica Consiglio
- CNR, National Research Council of Italy, Institute of Biosciences and Bioresources, Research Division Portici, Via Università 133, 80055, Portici, Italy
| | - Clara Conicella
- CNR, National Research Council of Italy, Institute of Biosciences and Bioresources, Research Division Portici, Via Università 133, 80055, Portici, Italy.
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34
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Barrales RR, Forn M, Georgescu PR, Sarkadi Z, Braun S. Control of heterochromatin localization and silencing by the nuclear membrane protein Lem2. Genes Dev 2016; 30:133-48. [PMID: 26744419 PMCID: PMC4719305 DOI: 10.1101/gad.271288.115] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Accepted: 12/07/2015] [Indexed: 01/08/2023]
Abstract
Transcriptionally silent chromatin localizes to the nuclear periphery, which provides a special microenvironment for gene repression. A variety of nuclear membrane proteins interact with repressed chromatin, yet the functional role of these interactions remains poorly understood. Here, we show that, in Schizosaccharomyces pombe, the nuclear membrane protein Lem2 associates with chromatin and mediates silencing and heterochromatin localization. Unexpectedly, we found that these functions can be separated and assigned to different structural domains within Lem2, excluding a simple tethering mechanism. Chromatin association and tethering of centromeres to the periphery are mediated by the N-terminal LEM (LAP2-Emerin-MAN1) domain of Lem2, whereas telomere anchoring and heterochromatin silencing require exclusively its conserved C-terminal MSC (MAN1-Src1 C-terminal) domain. Particularly, silencing by Lem2 is epistatic with the Snf2/HDAC (histone deacetylase) repressor complex SHREC at telomeres, while its necessity can be bypassed by deleting Epe1, a JmjC protein with anti-silencing activity. Furthermore, we found that loss of Lem2 reduces heterochromatin association of SHREC, which is accompanied by increased binding of Epe1. This reveals a critical function of Lem2 in coordinating these antagonistic factors at heterochromatin. The distinct silencing and localization functions mediated by Lem2 suggest that these conserved LEM-containing proteins go beyond simple tethering to play active roles in perinuclear silencing.
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Affiliation(s)
- Ramón Ramos Barrales
- Department of Physiological Chemistry, Biomedical Center, Ludwig-Maximilians-University of Munich, 82152 Martinsried, Germany
| | - Marta Forn
- Department of Physiological Chemistry, Biomedical Center, Ludwig-Maximilians-University of Munich, 82152 Martinsried, Germany
| | - Paula Raluca Georgescu
- Department of Physiological Chemistry, Biomedical Center, Ludwig-Maximilians-University of Munich, 82152 Martinsried, Germany
| | - Zsuzsa Sarkadi
- Department of Physiological Chemistry, Biomedical Center, Ludwig-Maximilians-University of Munich, 82152 Martinsried, Germany
| | - Sigurd Braun
- Department of Physiological Chemistry, Biomedical Center, Ludwig-Maximilians-University of Munich, 82152 Martinsried, Germany; International Max Planck Research School for Molecular and Cellular Life Sciences, 82152 Martinsried, Germany
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35
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Dukowic-Schulze S, Sundararajan A, Ramaraj T, Kianian S, Pawlowski WP, Mudge J, Chen C. Novel Meiotic miRNAs and Indications for a Role of PhasiRNAs in Meiosis. FRONTIERS IN PLANT SCIENCE 2016; 7:762. [PMID: 27313591 PMCID: PMC4889585 DOI: 10.3389/fpls.2016.00762] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Accepted: 05/17/2016] [Indexed: 05/03/2023]
Abstract
Small RNAs (sRNA) add additional layers to the regulation of gene expression, with siRNAs directing gene silencing at the DNA level by RdDM (RNA-directed DNA methylation), and micro RNAs (miRNAs) directing post-transcriptional regulation of specific target genes, mostly by mRNA cleavage. We used manually isolated male meiocytes from maize (Zea mays) to investigate sRNA and DNA methylation landscapes during zygotene, an early stage of meiosis during which steps of meiotic recombination and synapsis of paired homologous chromosomes take place. We discovered two novel miRNAs from meiocytes, zma-MIR11969 and zma-MIR11970, and identified putative target genes. Furthermore, we detected abundant phasiRNAs of 21 and 24 nt length. PhasiRNAs are phased small RNAs which occur in 21 or 24 nt intervals, at a few hundred loci, specifically in male reproductive tissues in grasses. So far, the function of phasiRNAs remained elusive. Data from isolated meiocytes now revealed elevated DNA methylation at phasiRNA loci, especially in the CHH context, suggesting a role for phasiRNAs in cis DNA methylation. In addition, we consider a role of these phasiRNAs in chromatin remodeling/dynamics during meiosis. However, this is not well supported yet and will need more additional data. Here, we only lay out the idea due to other relevant literature and our additional observation of a peculiar GC content pattern at phasiRNA loci. Chromatin remodeling is also indicated by the discovery that histone genes were enriched for sRNA of 22 nt length. Taken together, we gained clues that lead us to hypothesize sRNA-driven DNA methylation and possibly chromatin remodeling during male meiosis in the monocot maize which is in line with and extends previous knowledge.
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Affiliation(s)
| | | | | | - Shahryar Kianian
- Cereal Disease Laboratory, United States Department of Agriculture – Agricultural Research Service, St. PaulMN, USA
| | - Wojciech P. Pawlowski
- Section of Plant Biology, School of Integrative Plant Science, Cornell University, IthacaNY, USA
| | - Joann Mudge
- National Center for Genome Resources, Santa FeNM, USA
| | - Changbin Chen
- Department of Horticultural Science, University of Minnesota, St. PaulMN, USA
- *Correspondence: Changbin Chen,
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36
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Gal C, Moore KM, Paszkiewicz K, Kent NA, Whitehall SK. The impact of the HIRA histone chaperone upon global nucleosome architecture. Cell Cycle 2015; 14:123-34. [PMID: 25602522 PMCID: PMC4614360 DOI: 10.4161/15384101.2014.967123] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
HIRA is an evolutionarily conserved histone chaperone that mediates
replication-independent nucleosome assembly and is important for a variety of processes
such as cell cycle progression, development, and senescence. Here we have used a chromatin
sequencing approach to determine the genome-wide contribution of HIRA to nucleosome
organization in Schizosaccharomyces pombe. Cells lacking HIRA experience
a global reduction in nucleosome occupancy at gene sequences, consistent with the proposed
role for HIRA in chromatin reassembly behind elongating RNA polymerase II. In addition, we
find that at its target promoters, HIRA commonly maintains the full occupancy of the
−1 nucleosome. HIRA does not affect global chromatin structure at replication
origins or in rDNA repeats but is required for nucleosome occupancy in silent regions of
the genome. Nucleosome organization associated with the heterochromatic
(dg-dh) repeats located at the centromere is perturbed by loss of HIRA
function and furthermore HIRA is required for normal nucleosome occupancy at Tf2 LTR
retrotransposons. Overall, our data indicate that HIRA plays an important role in
maintaining nucleosome architecture at both euchromatic and heterochromatic loci.
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Affiliation(s)
- Csenge Gal
- a Institute for Cell & Molecular Biosciences ; Newcastle University ; Newcastle upon Tyne , UK
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37
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Regional centromeres in the yeast Candida lusitaniae lack pericentromeric heterochromatin. Proc Natl Acad Sci U S A 2015; 112:12139-44. [PMID: 26371315 DOI: 10.1073/pnas.1508749112] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Point centromeres are specified by a short consensus sequence that seeds kinetochore formation, whereas regional centromeres lack a conserved sequence and instead are epigenetically inherited. Regional centromeres are generally flanked by heterochromatin that ensures high levels of cohesin and promotes faithful chromosome segregation. However, it is not known whether regional centromeres require pericentromeric heterochromatin. In the yeast Candida lusitaniae, we identified a distinct type of regional centromere that lacks pericentromeric heterochromatin. Centromere locations were determined by ChIP-sequencing of two key centromere proteins, Cse4 and Mif2, and are consistent with bioinformatic predictions. The centromeric DNA sequence was unique for each chromosome and spanned 4-4.5 kbp, consistent with regional epigenetically inherited centromeres. However, unlike other regional centromeres, there was no evidence of pericentromeric heterochromatin in C. lusitaniae. In particular, flanking genes were expressed at a similar level to the rest of the genome, and a URA3 reporter inserted adjacent to a centromere was not repressed. In addition, regions flanking the centromeric core were not associated with hypoacetylated histones or a sirtuin deacetylase that generates heterochromatin in other yeast. Interestingly, the centromeric chromatin had a distinct pattern of histone modifications, being enriched for methylated H3K79 and H3R2 but lacking methylation of H3K4, which is found at other regional centromeres. Thus, not all regional centromeres require flanking heterochromatin.
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38
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Allshire RC, Ekwall K. Epigenetic Regulation of Chromatin States in Schizosaccharomyces pombe. Cold Spring Harb Perspect Biol 2015; 7:a018770. [PMID: 26134317 DOI: 10.1101/cshperspect.a018770] [Citation(s) in RCA: 126] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
This article discusses the advances made in epigenetic research using the model organism fission yeast Schizosaccharomyces pombe. S. pombe has been used for epigenetic research since the discovery of position effect variegation (PEV). This is a phenomenon in which a transgene inserted within heterochromatin is variably expressed, but can be stably inherited in subsequent cell generations. PEV occurs at centromeres, telomeres, ribosomal DNA (rDNA) loci, and mating-type regions of S. pombe chromosomes. Heterochromatin assembly in these regions requires enzymes that modify histones and the RNA interference (RNAi) machinery. One of the key histone-modifying enzymes is the lysine methyltransferase Clr4, which methylates histone H3 on lysine 9 (H3K9), a classic hallmark of heterochromatin. The kinetochore is assembled on specialized chromatin in which histone H3 is replaced by the variant CENP-A. Studies in fission yeast have contributed to our understanding of the establishment and maintenance of CENP-A chromatin and the epigenetic activation and inactivation of centromeres.
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Affiliation(s)
- Robin C Allshire
- Wellcome Trust Centre for Cell Biology, The University of Edinburgh, Edinburgh EH9 3JR, Scotland, United Kingdom
| | - Karl Ekwall
- Department of Biosciences and Nutrition, Karolinska Institutet, Center for Biosciences, NOVUM, S-141 83, Huddinge, Sweden
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39
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Aghcheh RK, Kubicek CP. Epigenetics as an emerging tool for improvement of fungal strains used in biotechnology. Appl Microbiol Biotechnol 2015; 99:6167-81. [PMID: 26115753 DOI: 10.1007/s00253-015-6763-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Revised: 06/07/2015] [Accepted: 06/10/2015] [Indexed: 10/23/2022]
Abstract
Filamentous fungi are today a major source of industrial biotechnology for the production of primary and secondary metabolites, as well as enzymes and recombinant proteins. All of them have undergone extensive improvement strain programs, initially by classical mutagenesis and later on by genetic manipulation. Thereby, strategies to overcome rate-limiting or yield-reducing reactions included manipulating the expression of individual genes, their regulatory genes, and also their function. Yet, research of the last decade clearly showed that cells can also undergo heritable changes in gene expression that do not involve changes in the underlying DNA sequences (=epigenetics). This involves three levels of regulation: (i) DNA methylation, (ii) chromatin remodeling by histone modification, and (iii) RNA interference. The demonstration of the occurrence of these processes in fungal model organisms such as Aspergillus nidulans and Neurospora crassa has stimulated its recent investigation as a tool for strain improvement in industrially used fungi. This review describes the progress that has thereby been obtained.
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Affiliation(s)
- Razieh Karimi Aghcheh
- Institute of Chemical Engineering, Vienna University of Technology, Getreidemarkt 9/166-5, 1060, Vienna, Austria,
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40
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Reyes C, Serrurier C, Gauthier T, Gachet Y, Tournier S. Aurora B prevents chromosome arm separation defects by promoting telomere dispersion and disjunction. ACTA ACUST UNITED AC 2015; 208:713-27. [PMID: 25778919 PMCID: PMC4362453 DOI: 10.1083/jcb.201407016] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The segregation of centromeres and telomeres at mitosis is coordinated at multiple levels to prevent the formation of aneuploid cells, a phenotype frequently observed in cancer. Mitotic instability arises from chromosome segregation defects, giving rise to chromatin bridges at anaphase. Most of these defects are corrected before anaphase onset by a mechanism involving Aurora B kinase, a key regulator of mitosis in a wide range of organisms. Here, we describe a new role for Aurora B in telomere dispersion and disjunction during fission yeast mitosis. Telomere dispersion initiates in metaphase, whereas disjunction takes place in anaphase. Dispersion is promoted by the dissociation of Swi6/HP1 and cohesin Rad21 from telomeres, whereas disjunction occurs at anaphase after the phosphorylation of condensin subunit Cnd2. Strikingly, we demonstrate that deletion of Ccq1, a telomeric shelterin component, rescued cell death after Aurora inhibition by promoting the loading of condensin on chromosome arms. Our findings reveal an essential role for telomeres in chromosome arm segregation.
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Affiliation(s)
- Céline Reyes
- Laboratoire de biologie cellulaire et moléculaire du contrôle de la prolifération, Université de Toulouse, F-31062 Toulouse, France Centre National de la Recherche Scientifique, LBCMCP-UMR5088, F-31062 Toulouse, France
| | - Céline Serrurier
- Laboratoire de biologie cellulaire et moléculaire du contrôle de la prolifération, Université de Toulouse, F-31062 Toulouse, France Centre National de la Recherche Scientifique, LBCMCP-UMR5088, F-31062 Toulouse, France
| | - Tiphaine Gauthier
- Laboratoire de biologie cellulaire et moléculaire du contrôle de la prolifération, Université de Toulouse, F-31062 Toulouse, France Centre National de la Recherche Scientifique, LBCMCP-UMR5088, F-31062 Toulouse, France
| | - Yannick Gachet
- Laboratoire de biologie cellulaire et moléculaire du contrôle de la prolifération, Université de Toulouse, F-31062 Toulouse, France Centre National de la Recherche Scientifique, LBCMCP-UMR5088, F-31062 Toulouse, France
| | - Sylvie Tournier
- Laboratoire de biologie cellulaire et moléculaire du contrôle de la prolifération, Université de Toulouse, F-31062 Toulouse, France Centre National de la Recherche Scientifique, LBCMCP-UMR5088, F-31062 Toulouse, France
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41
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Fennell A, Fernández-Álvarez A, Tomita K, Cooper JP. Telomeres and centromeres have interchangeable roles in promoting meiotic spindle formation. ACTA ACUST UNITED AC 2015; 208:415-28. [PMID: 25688135 PMCID: PMC4332249 DOI: 10.1083/jcb.201409058] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Both centromere–centrosome and telomere–centrosome contacts can promote spindle formation during meiosis. Telomeres and centromeres have traditionally been considered to perform distinct roles. During meiotic prophase, in a conserved chromosomal configuration called the bouquet, telomeres gather to the nuclear membrane (NM), often near centrosomes. We found previously that upon disruption of the fission yeast bouquet, centrosomes failed to insert into the NM at meiosis I and nucleate bipolar spindles. Hence, the trans-NM association of telomeres with centrosomes during prophase is crucial for efficient spindle formation. Nonetheless, in approximately half of bouquet-deficient meiocytes, spindles form properly. Here, we show that bouquet-deficient cells can successfully undergo meiosis using centromere–centrosome contact instead of telomere–centrosome contact to generate spindle formation. Accordingly, forced association between centromeres and centrosomes fully rescued the spindle defects incurred by bouquet disruption. Telomeres and centromeres both stimulate focal accumulation of the SUN domain protein Sad1 beneath the centrosome, suggesting a molecular underpinning for their shared spindle-generating ability. Our observations demonstrate an unanticipated level of interchangeability between the two most prominent chromosomal landmarks.
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Affiliation(s)
- Alex Fennell
- Telomere Biology Section, Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892 Telomere Biology Laboratory, Cancer Research UK, London Research Institute, London WC2A 3LY, England, UK
| | - Alfonso Fernández-Álvarez
- Telomere Biology Section, Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892 Telomere Biology Laboratory, Cancer Research UK, London Research Institute, London WC2A 3LY, England, UK
| | - Kazunori Tomita
- Chromosome Maintenance Group, UCL Cancer Institute, University College London, London WC1E 6DD, England, UK
| | - Julia Promisel Cooper
- Telomere Biology Section, Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892 Telomere Biology Laboratory, Cancer Research UK, London Research Institute, London WC2A 3LY, England, UK
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42
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Grand RS, Pichugina T, Gehlen LR, Jones MB, Tsai P, Allison JR, Martienssen R, O'Sullivan JM. Chromosome conformation maps in fission yeast reveal cell cycle dependent sub nuclear structure. Nucleic Acids Res 2014; 42:12585-99. [PMID: 25342201 PMCID: PMC4227791 DOI: 10.1093/nar/gku965] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Successful progression through the cell cycle requires spatial and temporal regulation of gene transcript levels and the number, positions and condensation levels of chromosomes. Here we present a high resolution survey of genome interactions in Schizosaccharomyces pombe using synchronized cells to investigate cell cycle dependent changes in genome organization and transcription. Cell cycle dependent interactions were captured between and within S. pombe chromosomes. Known features of genome organization (e.g. the clustering of telomeres and retrotransposon long terminal repeats (LTRs)) were observed throughout the cell cycle. There were clear correlations between transcript levels and chromosomal interactions between genes, consistent with a role for interactions in transcriptional regulation at specific stages of the cell cycle. In silico reconstructions of the chromosome organization within the S. pombe nuclei were made by polymer modeling. These models suggest that groups of genes with high and low, or differentially regulated transcript levels have preferred positions within the S. pombe nucleus. We conclude that the S. pombe nucleus is spatially divided into functional sub-nuclear domains that correlate with gene activity. The observation that chromosomal interactions are maintained even when chromosomes are fully condensed in M phase implicates genome organization in epigenetic inheritance and bookmarking.
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Affiliation(s)
- Ralph S Grand
- Liggins institute, University of Auckland, Grafton Auckland 1032, NZ Institute of Natural and Mathematical Sciences, Massey University, Albany, Auckland 0745, NZ
| | - Tatyana Pichugina
- Liggins institute, University of Auckland, Grafton Auckland 1032, NZ
| | - Lutz R Gehlen
- Institute of Natural and Mathematical Sciences, Massey University, Albany, Auckland 0745, NZ
| | - M Beatrix Jones
- Institute of Natural and Mathematical Sciences, Massey University, Albany, Auckland 0745, NZ
| | - Peter Tsai
- School of Biological Sciences, University of Auckland, Auckland 1023, NZ
| | - Jane R Allison
- Institute of Natural and Mathematical Sciences, Massey University, Albany, Auckland 0745, NZ
| | - Robert Martienssen
- HHMI-GBMF, Watson School of Biological Sciences, Cold Spring Harbor Laboratory, 1 Bungtown Road, Cold Spring Harbor, New York, NY 11724, USA
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45
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Wang J, Tadeo X, Hou H, Andrews S, Moresco JJ, Yates JR, Nagy PL, Jia S. Tls1 regulates splicing of shelterin components to control telomeric heterochromatin assembly and telomere length. Nucleic Acids Res 2014; 42:11419-32. [PMID: 25245948 PMCID: PMC4191416 DOI: 10.1093/nar/gku842] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Heterochromatin preferentially forms at repetitive DNA elements through RNAi-mediated targeting of histone-modifying enzymes. It was proposed that splicing factors interact with the RNAi machinery or regulate the splicing of repeat transcripts to directly participate in heterochromatin assembly. Here, by screening the fission yeast deletion library, we comprehensively identified factors required for telomeric heterochromatin assembly, including a novel gene tls1+. Purification of Tls1 and mass spectrometry analysis of its interacting proteins show that Tls1 associates with the spliceosome subunit Brr2. RNA sequencing analysis shows that the splicing of a subset of mRNAs are affected in tls1Δ cells, including mRNAs of shelterin components rap1+ and poz1+. Importantly, replacing rap1+ and poz1+ with their cDNAs significantly alleviated heterochromatin defects of tls1Δ cells, suggesting that the missplicing of shelterin components is the cause of such defects, and that splicing factors regulate telomeric heterochromatin through the proper splicing of heterochromatin factors. In addition to its role in telomeric heterochromatin assembly, Tls1-mediated splicing of shelterin mRNAs also regulates telomere length. Given that its human homologue C9ORF78 also associates with the spliceosome and is overexpressed in multiple cancer cell lines, our results suggest that C9ORF78 overexpression might alter the proper splicing of genes during cancer progression.
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Affiliation(s)
- Jiyong Wang
- Department of Biological Sciences, Columbia University, New York, NY, USA
| | - Xavier Tadeo
- Department of Biological Sciences, Columbia University, New York, NY, USA
| | - Haitong Hou
- Department of Biological Sciences, Columbia University, New York, NY, USA
| | - Stuart Andrews
- Department of Pathology and Cell Biology, Columbia University College of Physicians and Surgeons, New York, NY, USA
| | - James J Moresco
- Department of Chemical Physiology, The Scripps Research Institute, La Jolla, CA, USA
| | - John R Yates
- Department of Chemical Physiology, The Scripps Research Institute, La Jolla, CA, USA
| | - Peter L Nagy
- Department of Pathology and Cell Biology, Columbia University College of Physicians and Surgeons, New York, NY, USA
| | - Songtao Jia
- Department of Biological Sciences, Columbia University, New York, NY, USA
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Cohen AL, Jia S. Noncoding RNAs and the borders of heterochromatin. WILEY INTERDISCIPLINARY REVIEWS-RNA 2014; 5:835-47. [PMID: 25044367 DOI: 10.1002/wrna.1249] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2014] [Revised: 04/30/2014] [Accepted: 05/21/2014] [Indexed: 11/08/2022]
Abstract
Eukaryotic genomes contain long stretches of repetitive DNA sequences, which are the preferred sites for the assembly of heterochromatin structures. The formation of heterochromatin results in highly condensed chromosomal domains that limit the accessibility of DNA to the transcription and recombination machinery to maintain genome stability. Heterochromatin has the tendency to spread, and the formation of boundaries that block heterochromatin spreading is required to maintain stable gene expression patterns. Recent work has suggested that noncoding RNAs (ncRNAs) are involved in regulating boundary formation in addition to their well-established roles in chromatin regulation. Here, we present a review of our current understanding of the involvement of ncRNA at the boundaries of heterochromatin, highlighting their mechanisms of action in different settings.
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Affiliation(s)
- Allison L Cohen
- Department of Biological Sciences, Columbia University, New York, NY, USA
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Marker S, Carradec Q, Tanty V, Arnaiz O, Meyer E. A forward genetic screen reveals essential and non-essential RNAi factors in Paramecium tetraurelia. Nucleic Acids Res 2014; 42:7268-80. [PMID: 24860163 PMCID: PMC4066745 DOI: 10.1093/nar/gku223] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
In most eukaryotes, small RNA-mediated gene silencing pathways form complex interacting networks. In the ciliate Paramecium tetraurelia, at least two RNA interference (RNAi) mechanisms coexist, involving distinct but overlapping sets of protein factors and producing different types of short interfering RNAs (siRNAs). One is specifically triggered by high-copy transgenes, and the other by feeding cells with double-stranded RNA (dsRNA)-producing bacteria. In this study, we designed a forward genetic screen for mutants deficient in dsRNA-induced silencing, and a powerful method to identify the relevant mutations by whole-genome sequencing. We present a set of 47 mutant alleles for five genes, revealing two previously unknown RNAi factors: a novel Paramecium-specific protein (Pds1) and a Cid1-like nucleotidyl transferase. Analyses of allelic diversity distinguish non-essential and essential genes and suggest that the screen is saturated for non-essential, single-copy genes. We show that non-essential genes are specifically involved in dsRNA-induced RNAi while essential ones are also involved in transgene-induced RNAi. One of the latter, the RNA-dependent RNA polymerase RDR2, is further shown to be required for all known types of siRNAs, as well as for sexual reproduction. These results open the way for the dissection of the genetic complexity, interconnection, mechanisms and natural functions of RNAi pathways in P. tetraurelia.
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Affiliation(s)
- Simone Marker
- Ecole Normale Supérieure, Institut de Biologie de l'ENS, IBENS, Inserm, U1024, CNRS, UMR 8197, Paris F-75005, France
| | - Quentin Carradec
- Ecole Normale Supérieure, Institut de Biologie de l'ENS, IBENS, Inserm, U1024, CNRS, UMR 8197, Paris F-75005, France Sorbonne Universités, UPMC Univ., IFD, 4 place Jussieu, F-75252 Paris cedex 05, France
| | - Véronique Tanty
- Ecole Normale Supérieure, Institut de Biologie de l'ENS, IBENS, Inserm, U1024, CNRS, UMR 8197, Paris F-75005, France
| | - Olivier Arnaiz
- CNRS UPR3404 Centre de Génétique Moléculaire, Gif-sur-Yvette F-91198 cedex, France; Université Paris-Sud, Département de Biologie, Orsay, F-91405, France
| | - Eric Meyer
- Ecole Normale Supérieure, Institut de Biologie de l'ENS, IBENS, Inserm, U1024, CNRS, UMR 8197, Paris F-75005, France
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Cao Y, Wei J, Yang S, Sun J, Xu H, Wang Y, Zhao Y, He Q. RETRACTED ARTICLE: DDB1 and Cul4 are necessary for gene silencing and heterochromatin formation at pericentromeric regions in Neurospora. Protein Cell 2014. [PMID: 24818863 DOI: 10.1007/s13238-014-0067-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2014] [Accepted: 03/01/2014] [Indexed: 10/25/2022] Open
Affiliation(s)
- Yingqiong Cao
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, 100193, China
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Centromere identity from the DNA point of view. Chromosoma 2014; 123:313-25. [PMID: 24763964 PMCID: PMC4107277 DOI: 10.1007/s00412-014-0462-0] [Citation(s) in RCA: 135] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2013] [Revised: 03/28/2014] [Accepted: 04/01/2014] [Indexed: 02/05/2023]
Abstract
The centromere is a chromosomal locus responsible for the faithful segregation of genetic material during cell division. It has become evident that centromeres can be established literally on any DNA sequence, and the possible synergy between DNA sequences and the most prominent centromere identifiers, protein components, and epigenetic marks remains uncertain. However, some evolutionary preferences seem to exist, and long-term established centromeres are frequently formed on long arrays of satellite DNAs and/or transposable elements. Recent progress in understanding functional centromere sequences is based largely on the high-resolution DNA mapping of sequences that interact with the centromere-specific histone H3 variant, the most reliable marker of active centromeres. In addition, sequence assembly and mapping of large repetitive centromeric regions, as well as comparative genome analyses offer insight into their complex organization and evolution. The rapidly advancing field of transcription in centromere regions highlights the functional importance of centromeric transcripts. Here, we comprehensively review the current state of knowledge on the composition and functionality of DNA sequences underlying active centromeres and discuss their contribution to the functioning of different centromere types in higher eukaryotes.
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50
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DNA replication components as regulators of epigenetic inheritance--lesson from fission yeast centromere. Protein Cell 2014; 5:411-9. [PMID: 24691906 PMCID: PMC4026425 DOI: 10.1007/s13238-014-0049-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Accepted: 02/24/2014] [Indexed: 01/30/2023] Open
Abstract
Genetic information stored in DNA is accurately copied and transferred to subsequent generations through DNA replication. This process is accomplished through the concerted actions of highly conserved DNA replication components. Epigenetic information stored in the form of histone modifications and DNA methylation, constitutes a second layer of regulatory information important for many cellular processes, such as gene expression regulation, chromatin organization, and genome stability. During DNA replication, epigenetic information must also be faithfully transmitted to subsequent generations. How this monumental task is achieved remains poorly understood. In this review, we will discuss recent advances on the role of DNA replication components in the inheritance of epigenetic marks, with a particular focus on epigenetic regulation in fission yeast. Based on these findings, we propose that specific DNA replication components function as key regulators in the replication of epigenetic information across the genome.
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