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Chuang CN, Liu HC, Woo TT, Chao JL, Chen CY, Hu HT, Hsueh YP, Wang TF. Noncanonical usage of stop codons in ciliates expands proteins with structurally flexible Q-rich motifs. eLife 2024; 12:RP91405. [PMID: 38393970 PMCID: PMC10942620 DOI: 10.7554/elife.91405] [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: 02/25/2024] Open
Abstract
Serine(S)/threonine(T)-glutamine(Q) cluster domains (SCDs), polyglutamine (polyQ) tracts and polyglutamine/asparagine (polyQ/N) tracts are Q-rich motifs found in many proteins. SCDs often are intrinsically disordered regions that mediate protein phosphorylation and protein-protein interactions. PolyQ and polyQ/N tracts are structurally flexible sequences that trigger protein aggregation. We report that due to their high percentages of STQ or STQN amino acid content, four SCDs and three prion-causing Q/N-rich motifs of yeast proteins possess autonomous protein expression-enhancing activities. Since these Q-rich motifs can endow proteins with structural and functional plasticity, we suggest that they represent useful toolkits for evolutionary novelty. Comparative Gene Ontology (GO) analyses of the near-complete proteomes of 26 representative model eukaryotes reveal that Q-rich motifs prevail in proteins involved in specialized biological processes, including Saccharomyces cerevisiae RNA-mediated transposition and pseudohyphal growth, Candida albicans filamentous growth, ciliate peptidyl-glutamic acid modification and microtubule-based movement, Tetrahymena thermophila xylan catabolism and meiosis, Dictyostelium discoideum development and sexual cycles, Plasmodium falciparum infection, and the nervous systems of Drosophila melanogaster, Mus musculus and Homo sapiens. We also show that Q-rich-motif proteins are expanded massively in 10 ciliates with reassigned TAAQ and TAGQ codons. Notably, the usage frequency of CAGQ is much lower in ciliates with reassigned TAAQ and TAGQ codons than in organisms with expanded and unstable Q runs (e.g. D. melanogaster and H. sapiens), indicating that the use of noncanonical stop codons in ciliates may have coevolved with codon usage biases to avoid triplet repeat disorders mediated by CAG/GTC replication slippage.
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Affiliation(s)
| | - Hou-Cheng Liu
- Institute of Molecular Biology, Academia SinicaTaipeiTaiwan
| | - Tai-Ting Woo
- Institute of Molecular Biology, Academia SinicaTaipeiTaiwan
| | - Ju-Lan Chao
- Institute of Molecular Biology, Academia SinicaTaipeiTaiwan
| | - Chiung-Ya Chen
- Institute of Molecular Biology, Academia SinicaTaipeiTaiwan
| | - Hisao-Tang Hu
- Institute of Molecular Biology, Academia SinicaTaipeiTaiwan
| | - Yi-Ping Hsueh
- Institute of Molecular Biology, Academia SinicaTaipeiTaiwan
- Department of Biochemical Science and Technology, National Chiayi UniversityChiayiTaiwan
| | - Ting-Fang Wang
- Institute of Molecular Biology, Academia SinicaTaipeiTaiwan
- Department of Biochemical Science and Technology, National Chiayi UniversityChiayiTaiwan
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2
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Shehzada S, Noto T, Saksouk J, Mochizuki K. A SUMO E3 ligase promotes long non-coding RNA transcription to regulate small RNA-directed DNA elimination. eLife 2024; 13:e95337. [PMID: 38197489 PMCID: PMC10830130 DOI: 10.7554/elife.95337] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Accepted: 01/03/2024] [Indexed: 01/11/2024] Open
Abstract
Small RNAs target their complementary chromatin regions for gene silencing through nascent long non-coding RNAs (lncRNAs). In the ciliated protozoan Tetrahymena, the interaction between Piwi-associated small RNAs (scnRNAs) and the nascent lncRNA transcripts from the somatic genome has been proposed to induce target-directed small RNA degradation (TDSD), and scnRNAs not targeted for TDSD later target the germline-limited sequences for programmed DNA elimination. In this study, we show that the SUMO E3 ligase Ema2 is required for the accumulation of lncRNAs from the somatic genome and thus for TDSD and completing DNA elimination to make viable sexual progeny. Ema2 interacts with the SUMO E2 conjugating enzyme Ubc9 and enhances SUMOylation of the transcription regulator Spt6. We further show that Ema2 promotes the association of Spt6 and RNA polymerase II with chromatin. These results suggest that Ema2-directed SUMOylation actively promotes lncRNA transcription, which is a prerequisite for communication between the genome and small RNAs.
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Affiliation(s)
- Salman Shehzada
- Institute of Human Genetics (IGH), CNRS, University of MontpellierMontpellierFrance
| | - Tomoko Noto
- Institute of Human Genetics (IGH), CNRS, University of MontpellierMontpellierFrance
| | - Julie Saksouk
- Institute of Human Genetics (IGH), CNRS, University of MontpellierMontpellierFrance
| | - Kazufumi Mochizuki
- Institute of Human Genetics (IGH), CNRS, University of MontpellierMontpellierFrance
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3
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Bétermier M, Klobutcher LA, Orias E. Programmed chromosome fragmentation in ciliated protozoa: multiple means to chromosome ends. Microbiol Mol Biol Rev 2023; 87:e0018422. [PMID: 38009915 PMCID: PMC10732028 DOI: 10.1128/mmbr.00184-22] [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: 11/29/2023] Open
Abstract
SUMMARYCiliated protozoa undergo large-scale developmental rearrangement of their somatic genomes when forming a new transcriptionally active macronucleus during conjugation. This process includes the fragmentation of chromosomes derived from the germline, coupled with the efficient healing of the broken ends by de novo telomere addition. Here, we review what is known of developmental chromosome fragmentation in ciliates that have been well-studied at the molecular level (Tetrahymena, Paramecium, Euplotes, Stylonychia, and Oxytricha). These organisms differ substantially in the fidelity and precision of their fragmentation systems, as well as in the presence or absence of well-defined sequence elements that direct excision, suggesting that chromosome fragmentation systems have evolved multiple times and/or have been significantly altered during ciliate evolution. We propose a two-stage model for the evolution of the current ciliate systems, with both stages involving repetitive or transposable elements in the genome. The ancestral form of chromosome fragmentation is proposed to have been derived from the ciliate small RNA/chromatin modification process that removes transposons and other repetitive elements from the macronuclear genome during development. The evolution of this ancestral system is suggested to have potentiated its replacement in some ciliate lineages by subsequent fragmentation systems derived from mobile genetic elements.
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Affiliation(s)
- Mireille Bétermier
- Department of Genome Biology, Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell, Gif-sur-Yvette, France
| | - Lawrence A. Klobutcher
- Department of Molecular Biology and Biophysics, UCONN Health (University of Connecticut), Farmington, Connecticut, USA
| | - Eduardo Orias
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, California, USA
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4
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Horjales S, Li Calzi M, Francia ME, Cayota A, Garcia-Silva MR. piRNA pathway evolution beyond gonad context: Perspectives from apicomplexa and trypanosomatids. Front Genet 2023; 14:1129194. [PMID: 36816026 PMCID: PMC9935688 DOI: 10.3389/fgene.2023.1129194] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Accepted: 01/23/2023] [Indexed: 02/05/2023] Open
Abstract
piRNAs function as genome defense mechanisms against transposable elements insertions within germ line cells. Recent studies have unraveled that piRNA pathways are not limited to germ cells as initially reckoned, but are instead also found in non-gonadal somatic contexts. Moreover, these pathways have also been reported in bacteria, mollusks and arthropods, associated with safeguard of genomes against transposable elements, regulation of gene expression and with direct consequences in axon regeneration and memory formation. In this Perspective we draw attention to early branching parasitic protozoa, whose genome preservation is an essential function as in late eukaryotes. However, little is known about the defense mechanisms of these genomes. We and others have described the presence of putative PIWI-related machinery members in protozoan parasites. We have described the presence of a PIWI-like protein in Trypanosoma cruzi, bound to small non-coding RNAs (sRNAs) as cargo of secreted extracellular vesicles relevant in intercellular communication and host infection. Herein, we put forward the presence of members related to Argonaute pathways in both Trypanosoma cruzi and Toxoplasma gondii. The presence of PIWI-like machinery in Trypansomatids and Apicomplexa, respectively, could be evidence of an ancestral piRNA machinery that evolved to become more sophisticated and complex in multicellular eukaryotes. We propose a model in which ancient PIWI proteins were expressed broadly and had functions independent of germline maintenance. A better understanding of current and ancestral PIWI/piRNAs will be relevant to better understand key mechanisms of genome integrity conservation during cell cycle progression and modulation of host defense mechanisms by protozoan parasites.
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Affiliation(s)
- S. Horjales
- Apicomplexa Biology Laboratory, Institute Pasteur Montevideo, Montevideo, Uruguay
| | - M Li Calzi
- Functional Genomics Laboratory, Institute Pasteur Montevideo, Montevideo, Uruguay
| | - M. E. Francia
- Apicomplexa Biology Laboratory, Institute Pasteur Montevideo, Montevideo, Uruguay,Departamento de Parasitología y Micología, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay
| | - A. Cayota
- Functional Genomics Laboratory, Institute Pasteur Montevideo, Montevideo, Uruguay,Departmento Basico de Medicina, Facultad de Medicina, Hospital de Clinicas, Universidad de la República, Montevideo, Uruguay
| | - M. R. Garcia-Silva
- Functional Genomics Laboratory, Institute Pasteur Montevideo, Montevideo, Uruguay,*Correspondence: M. R. Garcia-Silva,
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5
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Wang M, Ogé L, Pérez Garcia MD, Launay-Avon A, Clément G, Le Gourrierec J, Hamama L, Sakr S. Antagonistic Effect of Sucrose Availability and Auxin on Rosa Axillary Bud Metabolism and Signaling, Based on the Transcriptomics and Metabolomics Analysis. FRONTIERS IN PLANT SCIENCE 2022; 13:830840. [PMID: 35392520 PMCID: PMC8982072 DOI: 10.3389/fpls.2022.830840] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Accepted: 02/02/2022] [Indexed: 06/14/2023]
Abstract
Shoot branching is crucial for successful plant development and plant response to environmental factors. Extensive investigations have revealed the involvement of an intricate regulatory network including hormones and sugars. Recent studies have demonstrated that two major systemic regulators-auxin and sugar-antagonistically regulate plant branching. However, little is known regarding the molecular mechanisms involved in this crosstalk. We carried out two complementary untargeted approaches-RNA-seq and metabolomics-on explant stem buds fed with different concentrations of auxin and sucrose resulting in dormant and non-dormant buds. Buds responded to the combined effect of auxin and sugar by massive reprogramming of the transcriptome and metabolome. The antagonistic effect of sucrose and auxin targeted several important physiological processes, including sink strength, the amino acid metabolism, the sulfate metabolism, ribosome biogenesis, the nucleic acid metabolism, and phytohormone signaling. Further experiments revealed a role of the TOR-kinase signaling pathway in bud outgrowth through at least downregulation of Rosa hybrida BRANCHED1 (RhBRC1). These new findings represent a cornerstone to further investigate the diverse molecular mechanisms that drive the integration of endogenous factors during shoot branching.
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Affiliation(s)
- Ming Wang
- Dryland-Technology Key Laboratory of Shandong Province, College of Agronomy, Qingdao Agricultural University, Qingdao, China
- Institut Agro, University of Angers INRAE, IRHS, SFR QUASAV, Angers, France
| | - Laurent Ogé
- Institut Agro, University of Angers INRAE, IRHS, SFR QUASAV, Angers, France
| | | | - Alexandra Launay-Avon
- Institute of Plant Sciences Paris-Saclay (IPS2), CNRS, INRA, Université Paris-Sud, Université d’Evry, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Gilles Clément
- Institut Jean-Pierre Bourgin, INRA, AgroParisTech, CNRS, Université Paris-Saclay, Versailles, France
| | - Jose Le Gourrierec
- Institut Agro, University of Angers INRAE, IRHS, SFR QUASAV, Angers, France
| | - Latifa Hamama
- Institut Agro, University of Angers INRAE, IRHS, SFR QUASAV, Angers, France
| | - Soulaiman Sakr
- Institut Agro, University of Angers INRAE, IRHS, SFR QUASAV, Angers, France
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6
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Kloc M, Kubiak JZ, Ghobrial RM. Natural genetic engineering: A programmed chromosome/DNA elimination. Dev Biol 2022; 486:15-25. [DOI: 10.1016/j.ydbio.2022.03.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Revised: 02/16/2022] [Accepted: 03/17/2022] [Indexed: 11/03/2022]
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7
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Ahsan R, Blanche W, Katz LA. Macronuclear development in ciliates, with a focus on nuclear architecture. J Eukaryot Microbiol 2022; 69:e12898. [PMID: 35178799 DOI: 10.1111/jeu.12898] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Revised: 01/20/2022] [Accepted: 02/14/2022] [Indexed: 11/30/2022]
Abstract
Ciliates are defined by the presence of dimorphic nuclei as they have both a somatic macronucleus and germline micronucleus within each individual cell. The size and structure of both germline micronuclei and somatic macronuclei varies tremendously among ciliates. Except just after conjugation (i.e. the nuclear exchange in sexual cycle), the germline micronucleus is transcriptionally-inactive and contains canonical chromosomes that will be inherited between generations. In contrast, the transcriptionally-active macronucleus contains chromosomes that vary in size in different classes of ciliates, with some lineages having extensively-fragmented gene-sized somatic chromosomes while others contain longer multigene chromosomes. Here, we describe the variation in somatic macronuclear architecture in lineages sampled across the ciliate tree of life, specifically focusing on lineages with extensively fragmented chromosomes (e.g. the classes Phyllopharyngea and Spirotrichea). Further, we synthesize information from the literature on the development of ciliate macronuclei, focusing on changes in nuclear architecture throughout life cycles. These data highlight the tremendous diversity among ciliate nuclear cycles, extend our understanding of patterns of genome evolution, and provide insight into different germline and somatic nuclear features (e.g. nuclear structure and development) among eukaryotes.
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Affiliation(s)
- Ragib Ahsan
- Department of Biological Sciences, Smith College, Northampton, Massachusetts, 01063, USA.,University of Massachusetts Amherst, Program in Organismic and Evolutionary Biology, Amherst, Massachusetts, 01003, USA
| | - Wumei Blanche
- Department of Biological Sciences, Smith College, Northampton, Massachusetts, 01063, USA
| | - Laura A Katz
- Department of Biological Sciences, Smith College, Northampton, Massachusetts, 01063, USA.,University of Massachusetts Amherst, Program in Organismic and Evolutionary Biology, Amherst, Massachusetts, 01003, USA
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8
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Jenkins BH, Maguire F, Leonard G, Eaton JD, West S, Housden BE, Milner DS, Richards TA. Characterization of the RNA-interference pathway as a tool for reverse genetic analysis in the nascent phototrophic endosymbiosis, Paramecium bursaria. ROYAL SOCIETY OPEN SCIENCE 2021; 8:210140. [PMID: 33996132 PMCID: PMC8059543 DOI: 10.1098/rsos.210140] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Accepted: 03/31/2021] [Indexed: 05/14/2023]
Abstract
Endosymbiosis was fundamental for the evolution of eukaryotic complexity. Endosymbiotic interactions can be dissected through forward- and reverse-genetic experiments, such as RNA-interference (RNAi). However, distinguishing small (s)RNA pathways in a eukaryote-eukaryote endosymbiotic interaction is challenging. Here, we investigate the repertoire of RNAi pathway protein-encoding genes in the model nascent endosymbiotic system, Paramecium bursaria-Chlorella spp. Using comparative genomics and transcriptomics supported by phylogenetics, we identify essential proteome components of the small interfering (si)RNA, scan (scn)RNA and internal eliminated sequence (ies)RNA pathways. Our analyses reveal that copies of these components have been retained throughout successive whole genome duplication (WGD) events in the Paramecium clade. We validate feeding-induced siRNA-based RNAi in P. bursaria via knock-down of the splicing factor, u2af1, which we show to be crucial to host growth. Finally, using simultaneous knock-down 'paradox' controls to rescue the effect of u2af1 knock-down, we demonstrate that feeding-induced RNAi in P. bursaria is dependent upon a core pathway of host-encoded Dcr1, Piwi and Pds1 components. Our experiments confirm the presence of a functional, host-derived RNAi pathway in P. bursaria that generates 23-nt siRNA, validating the use of the P. bursaria-Chlorella spp. system to investigate the genetic basis of a nascent endosymbiosis.
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Affiliation(s)
- Benjamin H. Jenkins
- Living Systems Institute and Biosciences, University of Exeter, Devon EX4 4QD, UK
- Department of Zoology, University of Oxford, 11a Mansfield Road, Oxford OX1 3SZ, UK
| | - Finlay Maguire
- Faculty of Computer Science, Dalhousie University, 6050 University Ave, Halifax, Nova Scotia, Canada B3H 1W5
| | - Guy Leonard
- Living Systems Institute and Biosciences, University of Exeter, Devon EX4 4QD, UK
- Department of Zoology, University of Oxford, 11a Mansfield Road, Oxford OX1 3SZ, UK
| | - Joshua D. Eaton
- Living Systems Institute and Biosciences, University of Exeter, Devon EX4 4QD, UK
| | - Steven West
- Living Systems Institute and Biosciences, University of Exeter, Devon EX4 4QD, UK
| | - Benjamin E. Housden
- Living Systems Institute and Biosciences, University of Exeter, Devon EX4 4QD, UK
| | - David S. Milner
- Living Systems Institute and Biosciences, University of Exeter, Devon EX4 4QD, UK
- Department of Zoology, University of Oxford, 11a Mansfield Road, Oxford OX1 3SZ, UK
| | - Thomas A. Richards
- Living Systems Institute and Biosciences, University of Exeter, Devon EX4 4QD, UK
- Department of Zoology, University of Oxford, 11a Mansfield Road, Oxford OX1 3SZ, UK
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9
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Bastiaanssen C, Joo C. Small RNA-directed DNA elimination: the molecular mechanism and its potential for genome editing. RNA Biol 2021; 18:1540-1545. [PMID: 33530834 PMCID: PMC8583303 DOI: 10.1080/15476286.2021.1885208] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
Abstract
Transposable elements have both detrimental and beneficial effects on their host genome. Tetrahymena is a unicellular eukaryote that deals with transposable elements in a unique way. It has a separate somatic and germline genome in two nuclei in a single cell. During sexual reproduction, a small RNA directed system compares the germline and somatic genome to identify transposable elements and related sequences. These are subsequently marked by heterochromatin and excised. In this Review, current knowledge of this system and the gaps therein are discussed. Additionally, the possibility to exploit the Tetrahymena machinery for genome editing and its advantages over the widely used CRISPR-Cas9 system will be explored. While the bacterial derived CRISPR-Cas9 has difficulty to access eukaryotic chromatin, Tetrahymena proteins are adept at acting in a chromatin context. Furthermore, Tetrahymena based gene therapy in humans might be a safer alternative to Cas9 because the latter can trigger an immune response.
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Affiliation(s)
- Carolien Bastiaanssen
- Department of BioNanoScience, Kavli Institute of Nanoscience, Delft University of Technology, Delft, The Netherlands
| | - Chirlmin Joo
- Department of BioNanoScience, Kavli Institute of Nanoscience, Delft University of Technology, Delft, The Netherlands
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10
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Xu J, Zhao X, Mao F, Basrur V, Ueberheide B, Chait BT, Allis CD, Taverna SD, Gao S, Wang W, Liu Y. A Polycomb repressive complex is required for RNAi-mediated heterochromatin formation and dynamic distribution of nuclear bodies. Nucleic Acids Res 2021; 49:5407-5425. [PMID: 33412588 PMCID: PMC8191774 DOI: 10.1093/nar/gkaa1262] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Revised: 12/02/2020] [Accepted: 01/04/2021] [Indexed: 01/17/2023] Open
Abstract
Polycomb group (PcG) proteins are widely utilized for transcriptional repression in eukaryotes. Here, we characterize, in the protist Tetrahymena thermophila, the EZL1 (E(z)-like 1) complex, with components conserved in metazoan Polycomb Repressive Complexes 1 and 2 (PRC1 and PRC2). The EZL1 complex is required for histone H3 K27 and K9 methylation, heterochromatin formation, transposable element control, and programmed genome rearrangement. The EZL1 complex interacts with EMA1, a helicase required for RNA interference (RNAi). This interaction is implicated in co-transcriptional recruitment of the EZL1 complex. Binding of H3K27 and H3K9 methylation by PDD1-another PcG protein interacting with the EZL1 complex-reinforces its chromatin association. The EZL1 complex is an integral part of Polycomb bodies, which exhibit dynamic distribution in Tetrahymena development: Their dispersion is driven by chromatin association, while their coalescence by PDD1, likely via phase separation. Our results provide a molecular mechanism connecting RNAi and Polycomb repression, which coordinately regulate nuclear bodies and reorganize the genome.
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Affiliation(s)
| | | | - Fengbiao Mao
- Department of Pathology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Venkatesha Basrur
- Proteomics Resource Facility, Department of Pathology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Beatrix Ueberheide
- Laboratory of Mass Spectrometry and Gaseous Ion Chemistry, the Rockefeller University, New York, NY 10065, USA
| | - Brian T Chait
- Laboratory of Mass Spectrometry and Gaseous Ion Chemistry, the Rockefeller University, New York, NY 10065, USA
| | - C David Allis
- Laboratory of Chromatin Biology and Epigenetics, the Rockefeller University, New York, NY 10065, USA
| | - Sean D Taverna
- Department of Pharmacology and Molecular Sciences and the Center for Epigenetics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Shan Gao
- Correspondence may also be addressed to Shan Gao.
| | - Wei Wang
- Correspondence may also be addressed to Wei Wang.
| | - Yifan Liu
- To whom correspondence should be addressed. Tel: +1 323 865 3852;
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11
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Cid NG, Puca G, Nudel CB, Nusblat AD. Genome analysis of sphingolipid metabolism-related genes in Tetrahymena thermophila and identification of a fatty acid 2-hydroxylase involved in the sexual stage of conjugation. Mol Microbiol 2020; 114:775-788. [PMID: 32713049 DOI: 10.1111/mmi.14578] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Revised: 07/15/2020] [Accepted: 07/16/2020] [Indexed: 11/29/2022]
Abstract
Sphingolipids are bioactive lipids present in all eukaryotes. Tetrahymena thermophila is a ciliate that displays remarkable sphingolipid moieties, that is, the unusual phosphonate-linked headgroup ceramides, present in membranes. To date, no identification has been made in this organism of the functions or related genes implicated in sphingolipid metabolism. By gathering information from the T. thermophila genome database together with sphingolipid moieties and enzymatic activities reported in other Tetrahymena species, we were able to reconstruct the putative de novo sphingolipid metabolic pathway in T. thermophila. Orthologous genes of 11 enzymatic steps involved in the biosynthesis and degradation pathways were retrieved. No genes related to glycosphingolipid or phosphonosphingolipid headgroup transfer were found, suggesting that both conserved and innovative mechanisms are used in ciliate. The knockout of gene TTHERM_00463850 allowed to identify the gene encoding a putative fatty acid 2-hydroxylase, which is involved in the biosynthesis pathway. Knockout cells have shown several impairments in the sexual stage of conjugation since different mating types of knockout strains failed to form cell pairs and complete the conjugation process. This fatty acid 2-hydroxylase gene is the first gene of a sphingolipid metabolic pathway to be identified in ciliates and have a critical role in their sexual stage.
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Affiliation(s)
- Nicolas G Cid
- Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Instituto de Nanobiotecnología (NANOBIOTEC), Buenos Aires, Argentina
| | - Gervasio Puca
- Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Instituto de Nanobiotecnología (NANOBIOTEC), Buenos Aires, Argentina
| | - Clara B Nudel
- Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Instituto de Nanobiotecnología (NANOBIOTEC), Buenos Aires, Argentina
| | - Alejandro D Nusblat
- Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Instituto de Nanobiotecnología (NANOBIOTEC), Buenos Aires, Argentina
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12
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Allen SE, Nowacki M. Roles of Noncoding RNAs in Ciliate Genome Architecture. J Mol Biol 2020; 432:4186-4198. [PMID: 31926952 PMCID: PMC7374600 DOI: 10.1016/j.jmb.2019.12.042] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Revised: 12/19/2019] [Accepted: 12/20/2019] [Indexed: 11/29/2022]
Abstract
Ciliates are an interesting model system for investigating diverse functions of noncoding RNAs, especially in genome defence pathways. During sexual development, the ciliate somatic genome undergoes massive rearrangement and reduction through removal of transposable elements and other repetitive DNA. This is guided by a multitude of noncoding RNAs of different sizes and functions, the extent of which is only recently becoming clear. The genome rearrangement pathways evolved as a defence against parasitic DNA, but interestingly also use the transposable elements and transposases to execute their own removal. Thus, ciliates are also a good model for the coevolution of host and transposable element, and the mutual dependence between the two. In this review, we summarise the genome rearrangement pathways in three diverse species of ciliate, with focus on recent discoveries and the roles of noncoding RNAs. Ciliate genomes undergo massive rearrangement and reduction during development. Transposon elimination is guided by small RNAs and carried out by transposases. New pathways for noncoding RNA production have recently been discovered in ciliates. Diverse ciliate species have different mechanisms for RNA-guided genome remodeling.
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Affiliation(s)
- Sarah E Allen
- Institute of Cell Biology, University of Bern, Switzerland
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13
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The completed macronuclear genome of a model ciliate Tetrahymena thermophila and its application in genome scrambling and copy number analyses. SCIENCE CHINA-LIFE SCIENCES 2020; 63:1534-1542. [PMID: 32297047 DOI: 10.1007/s11427-020-1689-4] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2020] [Accepted: 03/26/2020] [Indexed: 01/03/2023]
Abstract
The ciliate Tetrahymena thermophila has been a powerful model system for molecular and cellular biology. However, some investigations have been limited due to the incomplete closure and sequencing of the macronuclear genome assembly, which for many years has been stalled at 1,158 scaffolds, with large sections of unknown sequences (available in Tetrahymena Genome Database, TGD, http://ciliate.org/ ). Here we completed the first chromosome-level Tetrahymena macronuclear genome assembly, with approximately 300× long Single Molecule, Real-Time reads of the wild-type SB210 cells-the reference strain for the initial macronuclear genome sequencing project. All 181 chromosomes were capped with two telomeres and gaps were entirely closed. The completed genome shows significant improvements over the current assembly (TGD 2014) in both chromosome structure and sequence integrity. The majority of previously identified gene models shown in TGD were retained, with the addition of 36 new genes and 883 genes with modified gene models. The new genome and annotation were incorporated into TGD. This new genome allows for pursuit in some underexplored areas that were far more challenging previously; two of them, genome scrambling and chromosomal copy number, were investigated in this study. We expect that the completed macronuclear genome will facilitate many studies in Tetrahymena biology, as well as multiple lines of research in other eukaryotes.
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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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15
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Yu Y, Xiao J, Hann SS. The emerging roles of PIWI-interacting RNA in human cancers. Cancer Manag Res 2019; 11:5895-5909. [PMID: 31303794 PMCID: PMC6612017 DOI: 10.2147/cmar.s209300] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Accepted: 05/14/2019] [Indexed: 12/17/2022] Open
Abstract
PIWI-interacting RNAs (piRNAs) are a type of non-coding RNAs that interact with PIWI proteins, which are members of the argonaute family. Originally described in the germline, piRNAs are also expressed in human somatic cells in a tissue-specific manner. piRNAs are involved in spermatogenesis, germ stem-cell maintenance, silencing of transposon, epigenetic and genomic regulation and rearrangement. A large number of studies have demonstrated that expression of piRNAs is involved in many kinds of disease, including cancer. Abnormal expression of piRNAs is emerging as a critical player in cancer cell proliferation, apoptosis, invasion, and migration in vitro and in vivo. Functionally, piRNAs maintain genomic integrity by repressing the mobilization of transposable elements, and regulate the expression of downstream target genes via transcriptional or post-transcriptional mechanisms. Furthermore, altered expression of piRNAs in cancer is linked to clinical outcome, highlighting the important role that they may play as novel diagnostic and prognostic biomarkers, and as therapeutic targets for cancer therapy. In this review, we focus on the biogenesis and the functional roles of piRNAs in cancers, discuss emerging insights into the roles of piRNAs in the occurrence, progression, and treatment of cancers, reveal various mechanisms underlying piRNAs-mediated gene regulation, and highlight their potential clinical utilities as biomarkers as well as potential targets for cancer treatment.
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Affiliation(s)
- Yaya Yu
- Laboratory of Tumor Biology, The Second Clinical College of Guangzhou University of Chinese Medicine , Guangzhou, Guangdong Province, 510120, People's Republic of China
| | - Jing Xiao
- Department of Gynecology, The Second Clinical College of Guangzhou University of Chinese Medicine, Guangzhou, Guangdong Province, 510120, People's Republic of China
| | - Swei Sunny Hann
- Laboratory of Tumor Biology, The Second Clinical College of Guangzhou University of Chinese Medicine , Guangzhou, Guangdong Province, 510120, People's Republic of China.,Guangdong Provincial Key Laboratory of Clinical Research on Traditional Chinese Medicine Syndrome, The Second Clinical College of Guangzhou University of Chinese Medicine, Guangzhou, Guangdong Province, 510120, People's Republic of China
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16
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Maurer-Alcalá XX, Nowacki M. Evolutionary origins and impacts of genome architecture in ciliates. Ann N Y Acad Sci 2019; 1447:110-118. [PMID: 31074010 PMCID: PMC6767857 DOI: 10.1111/nyas.14108] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2018] [Revised: 03/18/2019] [Accepted: 04/03/2019] [Indexed: 01/24/2023]
Abstract
Genome architecture is well diversified among eukaryotes in terms of size and content, with many being radically shaped by ancient and ongoing genome conflicts with transposable elements (e.g., the large transposon‐rich genomes common among plants). In ciliates, a group of microbial eukaryotes with distinct somatic and germ‐line genomes present in a single cell, the consequences of these genome conflicts are most apparent in their developmentally programmed genome rearrangements. This complicated developmental phenomenon has largely overshadowed and outpaced our understanding of how germ‐line and somatic genome architectures have influenced the evolutionary dynamism and potential in these taxa. In our review, we highlight three central concepts: how the evolution of atypical ciliate germ‐line genome architectures is linked to ancient genome conflicts; how the complex, epigenetically guided transformation of germline to soma during development can generate widespread genetic variation; and how these features, coupled with their unusual life cycle, have increased the rate of molecular evolution linked to genome architecture in these taxa.
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Affiliation(s)
| | - Mariusz Nowacki
- Institute of Cell Biology, University of Bern, Bern, Switzerland
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17
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Zhao X, Xiong J, Mao F, Sheng Y, Chen X, Feng L, Dui W, Yang W, Kapusta A, Feschotte C, Coyne RS, Miao W, Gao S, Liu Y. RNAi-dependent Polycomb repression controls transposable elements in Tetrahymena. Genes Dev 2019; 33:348-364. [PMID: 30808657 PMCID: PMC6411011 DOI: 10.1101/gad.320796.118] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Accepted: 01/02/2019] [Indexed: 12/30/2022]
Abstract
In this study, Zhao et al. show that in the protozoan Tetrahymena thermophila, germline-specific internally eliminated sequences (IESs) become transcriptionally activated in mutants deficient in the RNAi-dependent Polycomb repression pathway. Their findings suggest that the interplay between RNAi and Polycomb repression is a widely conserved phenomenon whose ancestral role is epigenetic silencing of TEs. RNAi and Polycomb repression play evolutionarily conserved and often coordinated roles in transcriptional silencing. Here, we show that, in the protozoan Tetrahymena thermophila, germline-specific internally eliminated sequences (IESs)—many related to transposable elements (TEs)—become transcriptionally activated in mutants deficient in the RNAi-dependent Polycomb repression pathway. Germline TE mobilization also dramatically increases in these mutants. The transition from noncoding RNA (ncRNA) to mRNA production accompanies transcriptional activation of TE-related sequences and vice versa for transcriptional silencing. The balance between ncRNA and mRNA production is potentially affected by cotranscriptional processing as well as RNAi and Polycomb repression. We posit that interplay between RNAi and Polycomb repression is a widely conserved phenomenon, whose ancestral role is epigenetic silencing of TEs.
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Affiliation(s)
- Xiaolu Zhao
- Department of Pathology, University of Michigan, Ann Arbor, Michigan 48109, USA.,Institute of Evolution and Marine Biodiversity, Ocean University of China, Qingdao 266003, China
| | - Jie Xiong
- Key Laboratory of Aquatic Biodiversity and Conservation, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
| | - Fengbiao Mao
- Department of Pathology, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Yalan Sheng
- Institute of Evolution and Marine Biodiversity, Ocean University of China, Qingdao 266003, China.,Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266003, China
| | - Xiao Chen
- Department of Pathology, University of Michigan, Ann Arbor, Michigan 48109, USA.,Institute of Evolution and Marine Biodiversity, Ocean University of China, Qingdao 266003, China
| | - Lifang Feng
- Department of Pathology, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Wen Dui
- Department of Pathology, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Wentao Yang
- Key Laboratory of Aquatic Biodiversity and Conservation, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
| | - Aurélie Kapusta
- Department of Human Genetics, University of Utah School of Medicine, Salt Lake City, Utah 84112, USA
| | - Cédric Feschotte
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14850, USA
| | - Robert S Coyne
- J. Craig Venter Institute, Rockville, Maryland 20850, USA
| | - Wei Miao
- Key Laboratory of Aquatic Biodiversity and Conservation, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
| | - Shan Gao
- Institute of Evolution and Marine Biodiversity, Ocean University of China, Qingdao 266003, China.,Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266003, China
| | - Yifan Liu
- Department of Pathology, University of Michigan, Ann Arbor, Michigan 48109, USA
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18
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Affiliation(s)
- María E. Elguero
- Facultad de Farmacia y Bioquímica, Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Nanobiotecnología (NANOBIOTEC), Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Clara B. Nudel
- Facultad de Farmacia y Bioquímica, Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Nanobiotecnología (NANOBIOTEC), Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Alejandro D. Nusblat
- Facultad de Farmacia y Bioquímica, Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Nanobiotecnología (NANOBIOTEC), Universidad de Buenos Aires, Buenos Aires, Argentina
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19
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Postberg J, Jönsson F, Weil PP, Bulic A, Juranek SA, Lipps HJ. 27nt-RNAs guide histone variant deposition via 'RNA-induced DNA replication interference' and thus transmit parental genome partitioning in Stylonychia. Epigenetics Chromatin 2018; 11:31. [PMID: 29895326 PMCID: PMC5996456 DOI: 10.1186/s13072-018-0201-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Accepted: 06/04/2018] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND During sexual reproduction in the unicellular ciliate Stylonychia somatic macronuclei differentiate from germline micronuclei. Thereby, programmed sequence reduction takes place, leading to the elimination of > 95% of germline sequences, which priorly adopt heterochromatin structure via H3K27me3. Simultaneously, 27nt-ncRNAs become synthesized from parental transcripts and are bound by the Argonaute protein PIWI1. RESULTS These 27nt-ncRNAs cover sequences destined to the developing macronucleus and are thought to protect them from degradation. We provide evidence and propose that RNA/DNA base-pairing guides PIWI1/27nt-RNA complexes to complementary macronucleus-destined DNA target sequences, hence transiently causing locally stalled replication during polytene chromosome formation. This spatiotemporal delay enables the selective deposition of temporarily available histone H3.4K27me3 nucleosomes at all other sequences being continuously replicated, thus dictating their prospective heterochromatin structure before becoming developmentally eliminated. Concomitantly, 27nt-RNA-covered sites remain protected. CONCLUSIONS We introduce the concept of 'RNA-induced DNA replication interference' and explain how the parental functional genome partition could become transmitted to the progeny.
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Affiliation(s)
- Jan Postberg
- Clinical Molecular Genetics and Epigenetics, Centre for Biomedical Education and Research (ZBAF), Faculty of Health, Witten/Herdecke University, Alfred-Herrhausen-Str. 50, 58448 Witten, Germany
- HELIOS University Hospital Wuppertal, Centre for Clinical and Translational Research (CCTR), HELIOS Medical Centre Wuppertal, Witten/Herdecke University, Heusnerstr. 40, 42283 Wuppertal, Germany
| | - Franziska Jönsson
- Institute of Cell Biology, Centre for Biomedical Education and Research (ZBAF), Witten/Herdecke University, Witten, Germany
| | - Patrick Philipp Weil
- Clinical Molecular Genetics and Epigenetics, Centre for Biomedical Education and Research (ZBAF), Faculty of Health, Witten/Herdecke University, Alfred-Herrhausen-Str. 50, 58448 Witten, Germany
- HELIOS University Hospital Wuppertal, Centre for Clinical and Translational Research (CCTR), HELIOS Medical Centre Wuppertal, Witten/Herdecke University, Heusnerstr. 40, 42283 Wuppertal, Germany
| | - Aneta Bulic
- Institute of Cell Biology, Centre for Biomedical Education and Research (ZBAF), Witten/Herdecke University, Witten, Germany
| | - Stefan Andreas Juranek
- iPSC CRISPR Facility, European Research Institute for the Biology of Ageing (ERIBA), University Medical Center Groningen, Groningen, The Netherlands
| | - Hans-Joachim Lipps
- Institute of Cell Biology, Centre for Biomedical Education and Research (ZBAF), Witten/Herdecke University, Witten, Germany
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20
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Noto T, Mochizuki K. Whats, hows and whys of programmed DNA elimination in Tetrahymena. Open Biol 2018; 7:rsob.170172. [PMID: 29021213 PMCID: PMC5666084 DOI: 10.1098/rsob.170172] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Accepted: 09/12/2017] [Indexed: 12/20/2022] Open
Abstract
Programmed genome rearrangements in ciliates provide fascinating examples of flexible epigenetic genome regulations and important insights into the interaction between transposable elements (TEs) and host genomes. DNA elimination in Tetrahymena thermophila removes approximately 12 000 internal eliminated sequences (IESs), which correspond to one-third of the genome, when the somatic macronucleus (MAC) differentiates from the germline micronucleus (MIC). More than half of the IESs, many of which show high similarity to TEs, are targeted for elimination in cis by the small RNA-mediated genome comparison of the MIC to the MAC. Other IESs are targeted for elimination in trans by the same small RNAs through repetitive sequences. Furthermore, the small RNA–heterochromatin feedback loop ensures robust DNA elimination. Here, we review an updated picture of the DNA elimination mechanism, discuss the physiological and evolutionary roles of DNA elimination, and outline the key questions that remain unanswered.
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Affiliation(s)
- Tomoko Noto
- Institute of Human Genetics, UMR 9002, CNRS and University of Montpellier, Montpellier, France
| | - Kazufumi Mochizuki
- Institute of Human Genetics, UMR 9002, CNRS and University of Montpellier, Montpellier, France
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21
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Noto T, Mochizuki K. Small RNA-Mediated trans-Nuclear and trans-Element Communications in Tetrahymena DNA Elimination. Curr Biol 2018; 28:1938-1949.e5. [DOI: 10.1016/j.cub.2018.04.071] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Revised: 04/17/2018] [Accepted: 04/19/2018] [Indexed: 10/14/2022]
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22
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Grover JW, Kendall T, Baten A, Burgess D, Freeling M, King GJ, Mosher RA. Maternal components of RNA-directed DNA methylation are required for seed development in Brassica rapa. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2018; 94:575-582. [PMID: 29569777 DOI: 10.1111/tpj.13910] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Revised: 03/10/2018] [Accepted: 03/13/2018] [Indexed: 05/20/2023]
Abstract
Small RNAs trigger repressive DNA methylation at thousands of transposable elements in a process called RNA-directed DNA methylation (RdDM). The molecular mechanism of RdDM is well characterized in Arabidopsis, yet the biological function remains unclear, as loss of RdDM in Arabidopsis causes no overt defects, even after generations of inbreeding. It is known that 24 nucleotide Pol IV-dependent siRNAs, the hallmark of RdDM, are abundant in flowers and developing seeds, indicating that RdDM might be important during reproduction. Here we show that, unlike Arabidopsis, mutations in the Pol IV-dependent small RNA pathway cause severe and specific reproductive defects in Brassica rapa. High rates of abortion occur when seeds have RdDM mutant mothers, but not when they have mutant fathers. Although abortion occurs after fertilization, RdDM function is required in maternal somatic tissue, not in the female gametophyte or the developing zygote, suggesting that siRNAs from the maternal soma might function in filial tissues. We propose that recently outbreeding species such as B. rapa are key to understanding the role of RdDM during plant reproduction.
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Affiliation(s)
- Jeffrey W Grover
- Department of Molecular & Cellular Biology, The University of Arizona, Tucson, AZ, 85721, USA
| | - Timmy Kendall
- The School of Plant Sciences, The University of Arizona, Tucson, AZ, 85721, USA
| | - Abdul Baten
- Southern Cross Plant Science, Southern Cross University, Lismore, NSW, 2480, Australia
| | - Diane Burgess
- Department of Plant and Microbial Biology, The University of California, Berkeley, CA, 94720, USA
| | - Michael Freeling
- Department of Plant and Microbial Biology, The University of California, Berkeley, CA, 94720, USA
| | - Graham J King
- Southern Cross Plant Science, Southern Cross University, Lismore, NSW, 2480, Australia
| | - Rebecca A Mosher
- Department of Molecular & Cellular Biology, The University of Arizona, Tucson, AZ, 85721, USA
- The School of Plant Sciences, The University of Arizona, Tucson, AZ, 85721, USA
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23
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Michelini F, Jalihal AP, Francia S, Meers C, Neeb ZT, Rossiello F, Gioia U, Aguado J, Jones-Weinert C, Luke B, Biamonti G, Nowacki M, Storici F, Carninci P, Walter NG, d'Adda di Fagagna F. From "Cellular" RNA to "Smart" RNA: Multiple Roles of RNA in Genome Stability and Beyond. Chem Rev 2018; 118:4365-4403. [PMID: 29600857 DOI: 10.1021/acs.chemrev.7b00487] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Coding for proteins has been considered the main function of RNA since the "central dogma" of biology was proposed. The discovery of noncoding transcripts shed light on additional roles of RNA, ranging from the support of polypeptide synthesis, to the assembly of subnuclear structures, to gene expression modulation. Cellular RNA has therefore been recognized as a central player in often unanticipated biological processes, including genomic stability. This ever-expanding list of functions inspired us to think of RNA as a "smart" phone, which has replaced the older obsolete "cellular" phone. In this review, we summarize the last two decades of advances in research on the interface between RNA biology and genome stability. We start with an account of the emergence of noncoding RNA, and then we discuss the involvement of RNA in DNA damage signaling and repair, telomere maintenance, and genomic rearrangements. We continue with the depiction of single-molecule RNA detection techniques, and we conclude by illustrating the possibilities of RNA modulation in hopes of creating or improving new therapies. The widespread biological functions of RNA have made this molecule a reoccurring theme in basic and translational research, warranting it the transcendence from classically studied "cellular" RNA to "smart" RNA.
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Affiliation(s)
- Flavia Michelini
- IFOM - The FIRC Institute of Molecular Oncology , Milan , 20139 , Italy
| | - Ameya P Jalihal
- Single Molecule Analysis Group and Center for RNA Biomedicine, Department of Chemistry , University of Michigan , Ann Arbor , Michigan 48109-1055 , United States
| | - Sofia Francia
- IFOM - The FIRC Institute of Molecular Oncology , Milan , 20139 , Italy.,Istituto di Genetica Molecolare , CNR - Consiglio Nazionale delle Ricerche , Pavia , 27100 , Italy
| | - Chance Meers
- School of Biological Sciences , Georgia Institute of Technology , Atlanta , Georgia 30332 , United States
| | - Zachary T Neeb
- Institute of Cell Biology , University of Bern , Baltzerstrasse 4 , 3012 Bern , Switzerland
| | | | - Ubaldo Gioia
- IFOM - The FIRC Institute of Molecular Oncology , Milan , 20139 , Italy
| | - Julio Aguado
- IFOM - The FIRC Institute of Molecular Oncology , Milan , 20139 , Italy
| | | | - Brian Luke
- Institute of Developmental Biology and Neurobiology , Johannes Gutenberg University , 55099 Mainz , Germany.,Institute of Molecular Biology (IMB) , 55128 Mainz , Germany
| | - Giuseppe Biamonti
- Istituto di Genetica Molecolare , CNR - Consiglio Nazionale delle Ricerche , Pavia , 27100 , Italy
| | - Mariusz Nowacki
- Institute of Cell Biology , University of Bern , Baltzerstrasse 4 , 3012 Bern , Switzerland
| | - Francesca Storici
- School of Biological Sciences , Georgia Institute of Technology , Atlanta , Georgia 30332 , United States
| | - Piero Carninci
- RIKEN Center for Life Science Technologies , 1-7-22 Suehiro-cho, Tsurumi-ku , Yokohama City , Kanagawa 230-0045 , Japan
| | - Nils G Walter
- Single Molecule Analysis Group and Center for RNA Biomedicine, Department of Chemistry , University of Michigan , Ann Arbor , Michigan 48109-1055 , United States
| | - Fabrizio d'Adda di Fagagna
- IFOM - The FIRC Institute of Molecular Oncology , Milan , 20139 , Italy.,Istituto di Genetica Molecolare , CNR - Consiglio Nazionale delle Ricerche , Pavia , 27100 , Italy
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24
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Neeb ZT, Nowacki M. RNA-mediated transgenerational inheritance in ciliates and plants. Chromosoma 2018; 127:19-27. [PMID: 29230532 PMCID: PMC5818585 DOI: 10.1007/s00412-017-0655-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Revised: 12/05/2017] [Accepted: 12/05/2017] [Indexed: 11/30/2022]
Abstract
In the age of next-generation sequencing (NGS) and with the availability of whole sequenced genomes and epigenomes, some attention has shifted from purely sequence-based studies to those of heritable epigenetic modifications. Transgenerational inheritance can be defined as heritable changes to the state of DNA that may be passed on to subsequent generations without alterations to the underlying DNA sequence. Although this phenomenon has been extensively studied in many systems, studies of transgenerational inheritance in mammals and other higher-level eukaryotes may be complicated by the fact that many epigenetic marks are reprogrammed during sexual reproduction. This, by definition, may obscure our interpretation of what is in fact truly transgenerational. Therefore, in this mini review, we discuss what is currently known in the field about transgenerational epigenetic inheritance in ciliates and plants, with a particular emphasis on RNA-mediated processes and changes in chromatin states.
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Affiliation(s)
- Zachary T Neeb
- Institute of Cell Biology, University of Bern, Baltzerstrasse 4, 3012, Bern, Switzerland
| | - Mariusz Nowacki
- Institute of Cell Biology, University of Bern, Baltzerstrasse 4, 3012, Bern, Switzerland.
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25
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Abstract
In modern molecular biology, RNA has emerged as a versatile macromolecule capable of mediating an astonishing number of biological functions beyond its role as a transient messenger of genetic information. The recent discovery and functional analyses of new classes of noncoding RNAs (ncRNAs) have revealed their widespread use in many pathways, including several in the nucleus. This Review focuses on the mechanisms by which nuclear ncRNAs directly contribute to the maintenance of genome stability. We discuss how ncRNAs inhibit spurious recombination among repetitive DNA elements, repress mobilization of transposable elements (TEs), template or bridge DNA double-strand breaks (DSBs) during repair, and direct developmentally regulated genome rearrangements in some ciliates. These studies reveal an unexpected repertoire of mechanisms by which ncRNAs contribute to genome stability and even potentially fuel evolution by acting as templates for genome modification.
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26
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Small RNA-mediated repair of UV-induced DNA lesions by the DNA DAMAGE-BINDING PROTEIN 2 and ARGONAUTE 1. Proc Natl Acad Sci U S A 2017; 114:E2965-E2974. [PMID: 28325872 DOI: 10.1073/pnas.1618834114] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
As photosynthetic organisms, plants need to prevent irreversible UV-induced DNA lesions. Through an unbiased, genome-wide approach, we have uncovered a previously unrecognized interplay between Global Genome Repair and small interfering RNAs (siRNAs) in the recognition of DNA photoproducts, prevalently in intergenic regions. Genetic and biochemical approaches indicate that, upon UV irradiation, the DNA DAMAGE-BINDING PROTEIN 2 (DDB2) and ARGONAUTE 1 (AGO1) of Arabidopsis thaliana form a chromatin-bound complex together with 21-nt siRNAs, which likely facilitates recognition of DNA damages in an RNA/DNA complementary strand-specific manner. The biogenesis of photoproduct-associated siRNAs involves the noncanonical, concerted action of RNA POLYMERASE IV, RNA-DEPENDENT RNA POLYMERASE-2, and DICER-LIKE-4. Furthermore, the chromatin association/dissociation of the DDB2-AGO1 complex is under the control of siRNA abundance and DNA damage signaling. These findings reveal unexpected nuclear functions for DCL4 and AGO1, and shed light on the interplay between small RNAs and DNA repair recognition factors at damaged sites.
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27
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Neeb ZT, Hogan DJ, Katzman S, Zahler AM. Preferential expression of scores of functionally and evolutionarily diverse DNA and RNA-binding proteins during Oxytricha trifallax macronuclear development. PLoS One 2017; 12:e0170870. [PMID: 28207760 PMCID: PMC5312943 DOI: 10.1371/journal.pone.0170870] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2016] [Accepted: 01/11/2017] [Indexed: 12/04/2022] Open
Abstract
During its sexual reproduction, the stichotrichous ciliate Oxytricha trifallax orchestrates a remarkable transformation of one of the newly formed germline micronuclear genomes. Hundreds of thousands of gene pieces are stitched together, excised from chromosomes, and replicated dozens of times to yield a functional somatic macronuclear genome composed of ~16,000 distinct DNA molecules that typically encode a single gene. Little is known about the proteins that carry out this process. We profiled mRNA expression as a function of macronuclear development and identified hundreds of mRNAs preferentially expressed at specific times during the program. We find that a disproportionate number of these mRNAs encode proteins that are involved in DNA and RNA functions. Many mRNAs preferentially expressed during macronuclear development have paralogs that are either expressed constitutively or are expressed at different times during macronuclear development, including many components of the RNA polymerase II machinery and homologous recombination complexes. Hundreds of macronuclear development-specific genes encode proteins that are well-conserved among multicellular eukaryotes, including many with links to germline functions or development. Our work implicates dozens of DNA and RNA-binding proteins with diverse evolutionary trajectories in macronuclear development in O. trifallax. It suggests functional connections between the process of macronuclear development in unicellular ciliates and germline specialization and differentiation in multicellular organisms, and argues that gene duplication is a key source of evolutionary innovation in this process.
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Affiliation(s)
- Zachary T. Neeb
- Department of Molecular, Cell and Developmental Biology and Center for Molecular Biology of RNA, University of California Santa Cruz, Santa Cruz, California, United States of America
| | - Daniel J. Hogan
- Tocagen Inc., San Diego, California, United States of America
- * E-mail: (DJH); (AMZ)
| | - Sol Katzman
- Center for Biomolecular Science and Engineering, University of California Santa Cruz, Santa Cruz, California, United States of America
| | - Alan M. Zahler
- Department of Molecular, Cell and Developmental Biology and Center for Molecular Biology of RNA, University of California Santa Cruz, Santa Cruz, California, United States of America
- * E-mail: (DJH); (AMZ)
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Allen SE, Nowacki M. Necessity Is the Mother of Invention: Ciliates, Transposons, and Transgenerational Inheritance. Trends Genet 2017; 33:197-207. [PMID: 28174020 DOI: 10.1016/j.tig.2017.01.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Revised: 01/09/2017] [Accepted: 01/11/2017] [Indexed: 01/01/2023]
Abstract
Ciliates are a fascinating model system for the study of the interaction between eukaryotic germlines and somatic lines, especially with regard to the invasion and defence against transposable elements. They separate their germline and somatic line into two nuclei within the same cell, and they silence transposons and repetitive elements by way of deleting them from their somatic genome. This large-scale deletion event uses a series of intricate sequence targeting pathways involving small RNAs and transposases, part of which consists of a transnuclear comparison between maternal soma and daughter germline. We present recent progress in this dynamic field, and argue that these DNA targeting pathways provide an optimal system for the transgenerational inheritance of acquired traits. Ciliates thus also demonstrate the evolutionary value of transposable elements, both as sources of sequence diversity and also as drivers of adaptive evolution by necessitating defensive systems.
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Affiliation(s)
- Sarah E Allen
- Institute of Cell Biology, University of Bern, Baltzerstrasse 4, 3012 Bern, Switzerland
| | - Mariusz Nowacki
- Institute of Cell Biology, University of Bern, Baltzerstrasse 4, 3012 Bern, Switzerland.
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29
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Abstract
Ciliates are champions in programmed genome rearrangements. They carry out extensive restructuring during differentiation to drastically alter the complexity, relative copy number, and arrangement of sequences in the somatic genome. This chapter focuses on the model ciliate Tetrahymena, perhaps the simplest and best-understood ciliate studied. It summarizes past studies on various genome rearrangement processes and describes in detail the remarkable progress made in the past decade on the understanding of DNA deletion and other processes. The process occurs at thousands of specific sites to remove defined DNA segments that comprise roughly one-third of the genome including all transposons. Interestingly, this DNA rearranging process is a special form of RNA interference. It involves the production of double-stranded RNA and small RNA that guides the formation of heterochromatin. A domesticated piggyBac transposase is believed to cut off the marked chromatin, and the retained sequences are joined together through nonhomologous end-joining processes. Many of the proteins and DNA players involved have been analyzed and are described. This link provides possible explanations for the evolution, mechanism, and functional roles of the process. The article also discusses the interactions between parental and progeny somatic nuclei that affect the selection of sequences for deletion, and how the specific deletion boundaries are determined after heterochromatin marking.
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Tóth KF, Pezic D, Stuwe E, Webster A. The piRNA Pathway Guards the Germline Genome Against Transposable Elements. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 886:51-77. [PMID: 26659487 DOI: 10.1007/978-94-017-7417-8_4] [Citation(s) in RCA: 114] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
Transposable elements (TEs) have the capacity to replicate and insert into new genomic locations. This contributs significantly to evolution of genomes, but can also result in DNA breaks and illegitimate recombination, and therefore poses a significant threat to genomic integrity. Excess damage to the germ cell genome results in sterility. A specific RNA silencing pathway, termed the piRNA pathway operates in germ cells of animals to control TE activity. At the core of the piRNA pathway is a ribonucleoprotein complex consisting of a small RNA, called piRNA, and a protein from the PIWI subfamily of Argonaute nucleases. The piRNA pathway relies on the specificity provided by the piRNA sequence to recognize complementary TE targets, while effector functions are provided by the PIWI protein. PIWI-piRNA complexes silence TEs both at the transcriptional level - by attracting repressive chromatin modifications to genomic targets - and at the posttranscriptional level - by cleaving TE transcripts in the cytoplasm. Impairment of the piRNA pathway leads to overexpression of TEs, significantly compromised genome structure and, invariably, germ cell death and sterility.The piRNA pathway is best understood in the fruit fly, Drosophila melanogaster, and in mouse. This Chapter gives an overview of current knowledge on piRNA biogenesis, and mechanistic details of both transcriptional and posttranscriptional TE silencing by the piRNA pathway. It further focuses on the importance of post-translational modifications and subcellular localization of the piRNA machinery. Finally, it provides a brief description of analogous pathways in other systems.
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Affiliation(s)
- Katalin Fejes Tóth
- Division of Biology and Bioengineering, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA, 91125, USA.
| | - Dubravka Pezic
- Division of Biology and Bioengineering, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA, 91125, USA
| | - Evelyn Stuwe
- Division of Biology and Bioengineering, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA, 91125, USA
| | - Alexandre Webster
- Division of Biology and Bioengineering, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA, 91125, USA
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Lim RSM, Kai T. A piece of the pi(e): The diverse roles of animal piRNAs and their PIWI partners. Semin Cell Dev Biol 2015; 47-48:17-31. [PMID: 26582251 DOI: 10.1016/j.semcdb.2015.10.025] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Small non-coding RNAs are indispensable to many biological processes. A class of endogenous small RNAs, termed PIWI-interacting RNAs (piRNAs) because of their association with PIWI proteins, has known roles in safeguarding the genome against inordinate transposon mobilization, embryonic development, and stem cell regulation, among others. This review discusses the biogenesis of animal piRNAs and their diverse functions together with their PIWI protein partners, both in the germline and in somatic cells, and highlights the evolutionarily conserved aspects of these molecular players in animal biology.
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Affiliation(s)
- Robyn S M Lim
- Temasek Life Sciences Laboratory, National University of Singapore, Singapore 117604, Singapore; Department of Biological Sciences, National University of Singapore, Singapore 117543, Singapore.
| | - Toshie Kai
- Temasek Life Sciences Laboratory, National University of Singapore, Singapore 117604, Singapore; Department of Biological Sciences, National University of Singapore, Singapore 117543, Singapore.
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32
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Gebert D, Rosenkranz D. RNA-based regulation of transposon expression. WILEY INTERDISCIPLINARY REVIEWS-RNA 2015; 6:687-708. [DOI: 10.1002/wrna.1310] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Revised: 09/08/2015] [Accepted: 09/13/2015] [Indexed: 11/12/2022]
Affiliation(s)
- Daniel Gebert
- Institute of Anthropology; Johannes Gutenberg University; Mainz Germany
| | - David Rosenkranz
- Institute of Anthropology; Johannes Gutenberg University; Mainz Germany
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Chromodomain protein Tcd1 is required for macronuclear genome rearrangement and repair in Tetrahymena. Sci Rep 2015; 5:10243. [PMID: 25989344 PMCID: PMC4437310 DOI: 10.1038/srep10243] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Accepted: 04/07/2015] [Indexed: 11/25/2022] Open
Abstract
The survival of an organism’s progeny depends on the maintenance of its genome. Programmed DNA rearrangement and repair in Tetrahymena occur during the differentiation of the developing somatic macronuclear genome from the germ line micronuclear genome. Tetrahymena chromodomain protein (Tcd1) exhibited dynamic localization from the parental to the developing macronuclei. In the developing macronuclei, Tcd1 colocalized with Pdd1 and H3K9me3. Furthermore, Tcd1 colocalized with Pdd1 in the conjusome and “donut structure” of DNA elimination heterochromatin region. During the growth and conjugation stages, TCD1 knockout cells appeared normal and similar to wild-type strains. In addition, these knockout cells proceeded to the 2MAC-1MIC stage. However, the progeny of the TCD1 knockout cells did not grow upon return to SPP medium and eventually died. The deletion of the internal elimination sequence R element was partially disrupted in the developing new macronuclei. Gamma H2A staining showed that Tcd1 loss induced the accumulation of DNA double-strand breaks and the failure of genome repair. These results suggest that the chromodomain protein Tcd1 is required for the rearrangement and repair of new macronuclear genome in Tetrahymena.
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Assumpção CB, Calcagno DQ, Araújo TMT, Santos SEBD, Santos ÂKCRD, Riggins GJ, Burbano RR, Assumpção PP. The role of piRNA and its potential clinical implications in cancer. Epigenomics 2015; 7:975-84. [PMID: 25929784 PMCID: PMC4750480 DOI: 10.2217/epi.15.37] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Epigenetic mechanisms work in an orchestrated fashion to control gene expression in both homeostasis and diseases. Among small noncoding RNAs, piRNAs seem to meet the necessary requirements to be included in this epigenetic network due to their role in both transcriptional and post-transcriptional regulation. piRNAs and PIWI proteins might play important roles in cancer occurrence, prognosis and treatment as reported previously. Nevertheless, the potential clinical relevance of these molecules has yet been elucidated. A brief overview of piRNA biogenesis and their potential roles as part of an epigenetic network that is possibly involved in cancer is provided. Moreover, potential strategies based on the use of piRNAs and PIWI proteins as diagnostic and prognostic biomarkers as well as for cancer therapeutics are discussed.
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Affiliation(s)
- Carolina Baraúna Assumpção
- Laboratório de Citogenética Humana, Instituto de Ciências Biológicas, Universidade Federal do Pará, Rua Augusto Corrêa, 01, Guamá, CEP: 66075-110, Belém-PA, Brazil
| | - Danielle Queiroz Calcagno
- Núcleo de Pesquisas em Oncologia, Hospital Universitário João de Barros Barreto, Av. Mundurucus, 4487, Guamá, CEP: 66073-000, Belém-PA, Brazil
| | - Taíssa Maíra Thomaz Araújo
- Núcleo de Pesquisas em Oncologia, Hospital Universitário João de Barros Barreto, Av. Mundurucus, 4487, Guamá, CEP: 66073-000, Belém-PA, Brazil
| | - Sidney Emmanuel Batista dos Santos
- Núcleo de Pesquisas em Oncologia, Hospital Universitário João de Barros Barreto, Av. Mundurucus, 4487, Guamá, CEP: 66073-000, Belém-PA, Brazil
| | | | - Gregory Joseph Riggins
- Department of Neurosurgery, School of Medicine, Johns Hopkins University, 1550 Orleans Street, Room 257 CRB2, Baltimore, MD 21231, USA
| | - Rommel Rodriguez Burbano
- Laboratório de Citogenética Humana, Instituto de Ciências Biológicas, Universidade Federal do Pará, Rua Augusto Corrêa, 01, Guamá, CEP: 66075-110, Belém-PA, Brazil
| | - Paulo Pimentel Assumpção
- Núcleo de Pesquisas em Oncologia, Hospital Universitário João de Barros Barreto, Av. Mundurucus, 4487, Guamá, CEP: 66073-000, Belém-PA, Brazil
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35
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piRNA involvement in genome stability and human cancer. J Hematol Oncol 2015; 8:38. [PMID: 25895683 PMCID: PMC4412036 DOI: 10.1186/s13045-015-0133-5] [Citation(s) in RCA: 93] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2014] [Accepted: 03/31/2015] [Indexed: 12/16/2022] Open
Abstract
PIWI-interacting RNAs (piRNAs) are a large family of small, single-stranded, non-coding RNAs present throughout the animal kingdom. They form complexes with several members of the PIWI clade of Argonaute proteins and carry out regulatory functions. Their best established biological role is the inhibition of transposon mobilization, which they enforce both at the transcriptional level, through regulation of heterochromatin formation, and by promoting transcript degradation. In this capacity, piRNAs and PIWI proteins are at the heart of the germline cells’ efforts to preserve genome integrity. Additional regulatory roles of piRNAs and PIWI proteins in gene expression are becoming increasingly apparent. PIWI proteins and piRNAs are often detected in human cancers deriving from germline cells as well as somatic tissues. Their detection in cancer correlates with poorer clinical outcomes, suggesting that they play a functional role in the biology of cancer. Nonetheless, the currently available information, while highly suggestive, is still not sufficient to entirely discriminate between a ‘passenger’ role for the ectopic expression of piRNAs and PIWI proteins in cancer from a ‘driver’ role in the pathogenesis of these diseases. In this article, we review some of the key available evidence for the role of piRNAs and PIWI in human cancer and discuss ways in which our understanding of their functions may be improved.
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36
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Fukuda Y, Akematsu T, Attiq R, Tada C, Nakai Y, Pearlman RE. Role of the Cytosolic Heat Shock Protein 70 Ssa5 in the Ciliate Protozoan Tetrahymena thermophila. J Eukaryot Microbiol 2015; 62:481-93. [DOI: 10.1111/jeu.12203] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2014] [Revised: 11/17/2014] [Accepted: 12/08/2014] [Indexed: 12/29/2022]
Affiliation(s)
- Yasuhiro Fukuda
- Department of Biodiversity Science; Division of Biological Resource Science; Graduate School of Agricultural Science; Tohoku University; Osaki Japan
| | | | - Rizwan Attiq
- Department of Biology; York University; Toronto Ontario Canada
| | - Chika Tada
- Department of Biodiversity Science; Division of Biological Resource Science; Graduate School of Agricultural Science; Tohoku University; Osaki Japan
| | - Yutaka Nakai
- Department of Biodiversity Science; Division of Biological Resource Science; Graduate School of Agricultural Science; Tohoku University; Osaki Japan
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37
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Woehrer SL, Aronica L, Suhren JH, Busch CJL, Noto T, Mochizuki K. A Tetrahymena Hsp90 co-chaperone promotes siRNA loading by ATP-dependent and ATP-independent mechanisms. EMBO J 2015; 34:559-77. [PMID: 25588944 PMCID: PMC4331008 DOI: 10.15252/embj.201490062] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The loading of small interfering RNAs (siRNAs) and microRNAs into Argonaute proteins is enhanced by Hsp90 and ATP in diverse eukaryotes. However, whether this loading also occurs independently of Hsp90 and ATP remains unclear. We show that the Tetrahymena Hsp90 co-chaperone Coi12p promotes siRNA loading into the Argonaute protein Twi1p in both ATP-dependent and ATP-independent manners in vitro. The ATP-dependent activity requires Hsp90 and the tetratricopeptide repeat (TPR) domain of Coi12p, whereas these factors are dispensable for the ATP-independent activity. Both activities facilitate siRNA loading by counteracting the Twi1p-binding protein Giw1p, which is important to specifically sort the 26- to 32-nt siRNAs to Twi1p. Although Coi12p lacking its TPR domain does not bind to Hsp90, it can partially restore the siRNA loading and DNA elimination defects of COI12 knockout cells, suggesting that Hsp90- and ATP-independent loading of siRNA occurs in vivo and plays a physiological role in Tetrahymena.
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Affiliation(s)
- Sophie L Woehrer
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna, Austria
| | - Lucia Aronica
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna, Austria
| | - Jan H Suhren
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna, Austria
| | - Clara Jana-Lui Busch
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna, Austria
| | - Tomoko Noto
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna, Austria
| | - Kazufumi Mochizuki
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna, Austria
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38
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Swart EC, Nowacki M. The eukaryotic way to defend and edit genomes by sRNA-targeted DNA deletion. Ann N Y Acad Sci 2015; 1341:106-14. [PMID: 25581723 DOI: 10.1111/nyas.12636] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
While there is currently burgeoning interest in the application of the CRISPR/Cas (clustered regularly interspaced short palindromic repeats/CRISPR-associated genes) to genome editing, it is perhaps not widely appreciated that this is the second discovery of a small RNA (sRNA)-targeted DNA-deletion system. The first sRNA-targeted DNA-deletion system to be discovered, which we call IES/Ias (internal eliminated sequence/IES-associated genes) to contrast with CRISPR/Cas, is found in ciliates, and, like CRISPR/Cas, is thought to serve as a form of immune defense against invasive DNAs. The manner in which the ciliate IES/Ias system functions is distinct from that of the CRISPR/Cas system in archaea and bacteria, and arose independently through a synthesis of RNA interference-derived and DNA-specific molecular components. Despite the major differences between CRISPR/Cas and IES/Ias, both systems face similar conceptual challenges in targeting invasive DNAs. In this review, we focus on the discovery, effects, function, and evolutionary consequences of the IES/Ias system.
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Affiliation(s)
- Estienne C Swart
- Institute of Cell Biology, University of Bern, Bern, Switzerland
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39
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Arambasic M, Sandoval PY, Hoehener C, Singh A, Swart EC, Nowacki M. Pdsg1 and Pdsg2, novel proteins involved in developmental genome remodelling in Paramecium. PLoS One 2014; 9:e112899. [PMID: 25397898 PMCID: PMC4232520 DOI: 10.1371/journal.pone.0112899] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Accepted: 10/16/2014] [Indexed: 01/25/2023] Open
Abstract
The epigenetic influence of maternal cells on the development of their progeny has long been studied in various eukaryotes. Multicellular organisms usually provide their zygotes not only with nutrients but also with functional elements required for proper development, such as coding and non-coding RNAs. These maternally deposited RNAs exhibit a variety of functions, from regulating gene expression to assuring genome integrity. In ciliates, such as Paramecium these RNAs participate in the programming of large-scale genome reorganization during development, distinguishing germline-limited DNA, which is excised, from somatic-destined DNA. Only a handful of proteins playing roles in this process have been identified so far, including typical RNAi-derived factors such as Dicer-like and Piwi proteins. Here we report and characterize two novel proteins, Pdsg1 and Pdsg2 (Paramecium protein involved in Development of the Somatic Genome 1 and 2), involved in Paramecium genome reorganization. We show that these proteins are necessary for the excision of germline-limited DNA during development and the survival of sexual progeny. Knockdown of PDSG1 and PDSG2 genes affects the populations of small RNAs known to be involved in the programming of DNA elimination (scanRNAs and iesRNAs) and chromatin modification patterns during development. Our results suggest an association between RNA-mediated trans-generational epigenetic signal and chromatin modifications in the process of Paramecium genome reorganization.
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Affiliation(s)
| | | | | | - Aditi Singh
- Institute of Cell Biology, University of Bern, Bern, Switzerland
| | | | - Mariusz Nowacki
- Institute of Cell Biology, University of Bern, Bern, Switzerland
- * E-mail:
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40
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Tetrahymena Pot2 is a developmentally regulated paralog of Pot1 that localizes to chromosome breakage sites but not to telomeres. EUKARYOTIC CELL 2014; 13:1519-29. [PMID: 25303953 DOI: 10.1128/ec.00204-14] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Tetrahymena telomeres are protected by a protein complex composed of Pot1, Tpt1, Pat1, and Pat2. Pot1 binds the 3' overhang and serves multiple roles in telomere maintenance. Here we describe Pot2, a paralog of Pot1 which has evolved a novel function during Tetrahymena sexual reproduction. Pot2 is unnecessary for telomere maintenance during vegetative growth, as the telomere structure is unaffected by POT2 macronuclear gene disruption. Pot2 is expressed only in mated cells, where it accumulates in developing macronuclei around the time of two chromosome processing events: internal eliminated sequence (IES) excision and chromosome breakage. Chromatin immunoprecipitation (ChIP) demonstrated Pot2 localization to regions of chromosome breakage but not to telomeres or IESs. Pot2 association with chromosome breakage sites (CBSs) occurs slightly before chromosome breakage. Pot2 did not bind CBSs or telomeric DNA in vitro, suggesting that it is recruited to CBSs by another factor. The telomere proteins Pot1, Pat1, and Tpt1 and the IES binding factor Pdd1 fail to colocalize with Pot2. Thus, Pot2 is the first protein found to associate specifically with CBSs. The selective association of Pot2 versus Pdd1 with CBSs or IESs indicates a mechanistic difference between the chromosome processing events at these two sites. Moreover, ChIP revealed that histone marks characteristic of IES processing, H3K9me3 and H3K27me3, are absent from CBSs. Thus, the mechanisms of chromosome breakage and IES excision must be fundamentally different. Our results lead to a model where Pot2 directs chromosome breakage by recruiting telomerase and/or the endonuclease responsible for DNA cleavage to CBSs.
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Swart EC, Wilkes CD, Sandoval PY, Arambasic M, Sperling L, Nowacki M. Genome-wide analysis of genetic and epigenetic control of programmed DNA deletion. Nucleic Acids Res 2014; 42:8970-83. [PMID: 25016527 PMCID: PMC4132734 DOI: 10.1093/nar/gku619] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
During the development of the somatic genome from the Paramecium germline genome the bulk of the copies of ∼45 000 unique, internal eliminated sequences (IESs) are deleted. IES targeting is facilitated by two small RNA (sRNA) classes: scnRNAs, which relay epigenetic information from the parental nucleus to the developing nucleus, and iesRNAs, which are produced and used in the developing nucleus. Why only certain IESs require sRNAs for their removal has been enigmatic. By analyzing the silencing effects of three genes: PGM (responsible for DNA excision), DCL2/3 (scnRNA production) and DCL5 (iesRNA production), we identify key properties required for IES elimination. Based on these results, we propose that, depending on the exact combination of their lengths and end bases, some IESs are less efficiently recognized or excised and have a greater requirement for targeting by scnRNAs and iesRNAs. We suggest that the variation in IES retention following silencing of DCL2/3 is not primarily due to scnRNA density, which is comparatively uniform relative to IES retention, but rather the genetic properties of IESs. Taken together, our analyses demonstrate that in Paramecium the underlying genetic properties of developmentally deleted DNA sequences are essential in determining the sensitivity of these sequences to epigenetic control.
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Affiliation(s)
- Estienne C Swart
- Institute of Cell Biology, University of Bern, Baltzerstrasse 4, 3012 Bern, Switzerland
| | - Cyril Denby Wilkes
- CNRS UPR3404 Centre de Génétique Moléculaire, 1 avenue de la Terrasse, Gif-sur-Yvette F-91198 cedex, France Université Paris-Sud, Département de Biologie, Orsay, F-91405, France
| | - Pamela Y Sandoval
- Institute of Cell Biology, University of Bern, Baltzerstrasse 4, 3012 Bern, Switzerland
| | - Miroslav Arambasic
- Institute of Cell Biology, University of Bern, Baltzerstrasse 4, 3012 Bern, Switzerland
| | - Linda Sperling
- CNRS UPR3404 Centre de Génétique Moléculaire, 1 avenue de la Terrasse, Gif-sur-Yvette F-91198 cedex, France Université Paris-Sud, Département de Biologie, Orsay, F-91405, France
| | - Mariusz Nowacki
- Institute of Cell Biology, University of Bern, Baltzerstrasse 4, 3012 Bern, Switzerland
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42
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Noto T, Kurth HM, Mochizuki K. Analysis of Piwi-loaded small RNAs in Tetrahymena. Methods Mol Biol 2014; 1093:209-24. [PMID: 24178568 DOI: 10.1007/978-1-62703-694-8_17] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Scan RNAs (scnRNAs) are developmentally regulated siRNAs of ~26-32 nucleotides in length that are involved in programmed DNA elimination in Tetrahymena. scnRNAs are loaded onto the Piwi-related protein Twi1p and 2'-O-methylated at their 3' termini. We describe two alternative strategies for analyzing the Twi1p-loaded scnRNAs: preparation of loaded scnRNAs by immuno-purification of the Twi1p-scnRNA complex and exclusion of non-methylated scnRNAs during cDNA library construction using periodate oxidation.
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Affiliation(s)
- Tomoko Noto
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences, Vienna, Austria
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43
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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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Singh DP, Saudemont B, Guglielmi G, Arnaiz O, Goût JF, Prajer M, Potekhin A, Przybòs E, Aubusson-Fleury A, Bhullar S, Bouhouche K, Lhuillier-Akakpo M, Tanty V, Blugeon C, Alberti A, Labadie K, Aury JM, Sperling L, Duharcourt S, Meyer E. Genome-defence small RNAs exapted for epigenetic mating-type inheritance. Nature 2014; 509:447-52. [PMID: 24805235 DOI: 10.1038/nature13318] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2013] [Accepted: 04/11/2014] [Indexed: 12/30/2022]
Abstract
In the ciliate Paramecium, transposable elements and their single-copy remnants are deleted during the development of somatic macronuclei from germline micronuclei, at each sexual generation. Deletions are targeted by scnRNAs, small RNAs produced from the germ line during meiosis that first scan the maternal macronuclear genome to identify missing sequences, and then allow the zygotic macronucleus to reproduce the same deletions. Here we show that this process accounts for the maternal inheritance of mating types in Paramecium tetraurelia, a long-standing problem in epigenetics. Mating type E depends on expression of the transmembrane protein mtA, and the default type O is determined during development by scnRNA-dependent excision of the mtA promoter. In the sibling species Paramecium septaurelia, mating type O is determined by coding-sequence deletions in a different gene, mtB, which is specifically required for mtA expression. These independently evolved mechanisms suggest frequent exaptation of the scnRNA pathway to regulate cellular genes and mediate transgenerational epigenetic inheritance of essential phenotypic polymorphisms.
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Affiliation(s)
- Deepankar Pratap Singh
- 1] Ecole Normale Supérieure, Institut de Biologie de l'ENS, IBENS; Inserm, U1024; CNRS, UMR 8197 Paris F-75005, France [2] Sorbonne Universités, UPMC Univ., IFD, 4 place Jussieu, 75252 Paris cedex 05, France
| | - Baptiste Saudemont
- 1] Ecole Normale Supérieure, Institut de Biologie de l'ENS, IBENS; Inserm, U1024; CNRS, UMR 8197 Paris F-75005, France [2] Sorbonne Universités, UPMC Univ., IFD, 4 place Jussieu, 75252 Paris cedex 05, France [3] Laboratoire de Biochimie, Unité Mixte de Recherche 8231, École Supérieure de Physique et de Chimie Industrielles, 75231 Paris, France (B.S.); Department of Biology, Indiana University, Bloomington, Indiana 47405, USA (J.-F.G.); INRA, UMR 1061 Unité de Génétique Moléculaire Animale, Université de Limoges, IFR 145, Faculté des Sciences et Techniques, 87060 Limoges, France (K.B.)
| | - Gérard Guglielmi
- 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, and Université Paris-Sud, Département de Biologie, Orsay F-91405, France
| | - Jean-François Goût
- 1] CNRS UMR5558, Laboratoire de Biométrie et Biologie Evolutive, Université de Lyon, 43 boulevard du 11 Novembre 1918, Villeurbanne F-69622, France [2] Laboratoire de Biochimie, Unité Mixte de Recherche 8231, École Supérieure de Physique et de Chimie Industrielles, 75231 Paris, France (B.S.); Department of Biology, Indiana University, Bloomington, Indiana 47405, USA (J.-F.G.); INRA, UMR 1061 Unité de Génétique Moléculaire Animale, Université de Limoges, IFR 145, Faculté des Sciences et Techniques, 87060 Limoges, France (K.B.)
| | - Malgorzata Prajer
- Institute of Systematics and Evolution of Animals, Polish Academy of Sciences, Sławkowska 17, 31-016 Krakow, Poland
| | - Alexey Potekhin
- Department of Microbiology, Faculty of Biology, St Petersburg State University, Saint Petersburg 199034, Russia
| | - Ewa Przybòs
- Institute of Systematics and Evolution of Animals, Polish Academy of Sciences, Sławkowska 17, 31-016 Krakow, Poland
| | - Anne Aubusson-Fleury
- CNRS UPR3404 Centre de Génétique Moléculaire, Gif-sur-Yvette F-91198, and Université Paris-Sud, Département de Biologie, Orsay F-91405, France
| | - Simran Bhullar
- Ecole Normale Supérieure, Institut de Biologie de l'ENS, IBENS; Inserm, U1024; CNRS, UMR 8197 Paris F-75005, France
| | - Khaled Bouhouche
- 1] Ecole Normale Supérieure, Institut de Biologie de l'ENS, IBENS; Inserm, U1024; CNRS, UMR 8197 Paris F-75005, France [2] Laboratoire de Biochimie, Unité Mixte de Recherche 8231, École Supérieure de Physique et de Chimie Industrielles, 75231 Paris, France (B.S.); Department of Biology, Indiana University, Bloomington, Indiana 47405, USA (J.-F.G.); INRA, UMR 1061 Unité de Génétique Moléculaire Animale, Université de Limoges, IFR 145, Faculté des Sciences et Techniques, 87060 Limoges, France (K.B.)
| | - Maoussi Lhuillier-Akakpo
- 1] Sorbonne Universités, UPMC Univ., IFD, 4 place Jussieu, 75252 Paris cedex 05, France [2] Institut Jacques Monod, CNRS, UMR 7592, Université Paris Diderot, Sorbonne Paris Cité, Paris F-75205, France
| | - Véronique Tanty
- Ecole Normale Supérieure, Institut de Biologie de l'ENS, IBENS; Inserm, U1024; CNRS, UMR 8197 Paris F-75005, France
| | - Corinne Blugeon
- Ecole Normale Supérieure, Institut de Biologie de l'ENS, IBENS; Inserm, U1024; CNRS, UMR 8197 Paris F-75005, France
| | - Adriana Alberti
- Commissariat à l'Energie Atomique (CEA), Institut de Génomique (IG), Genoscope, 2 rue Gaston Crémieux, BP5706, 91057 Evry, France
| | - Karine Labadie
- Commissariat à l'Energie Atomique (CEA), Institut de Génomique (IG), Genoscope, 2 rue Gaston Crémieux, BP5706, 91057 Evry, France
| | - Jean-Marc Aury
- Commissariat à l'Energie Atomique (CEA), Institut de Génomique (IG), Genoscope, 2 rue Gaston Crémieux, BP5706, 91057 Evry, France
| | - Linda Sperling
- CNRS UPR3404 Centre de Génétique Moléculaire, Gif-sur-Yvette F-91198, and Université Paris-Sud, Département de Biologie, Orsay F-91405, France
| | - Sandra Duharcourt
- Institut Jacques Monod, CNRS, UMR 7592, Université Paris Diderot, Sorbonne Paris Cité, Paris F-75205, 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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Xie F, Stewart CN, Taki FA, He Q, Liu H, Zhang B. High-throughput deep sequencing shows that microRNAs play important roles in switchgrass responses to drought and salinity stress. PLANT BIOTECHNOLOGY JOURNAL 2014; 12:354-66. [PMID: 24283289 DOI: 10.1111/pbi.12142] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2013] [Revised: 09/22/2013] [Accepted: 10/03/2013] [Indexed: 05/20/2023]
Abstract
MicroRNAs (miRNAs) are an important class of small regulatory RNAs. The goal of this study was to analyse stress-responsive miRNAs in switchgrass (Panicum virgatum), the emerging biofuel crop, to facilitate choosing gene targets for improving biomass and biofuel yield. After sequencing three small RNA libraries constructed from control, salt- and drought-treated switchgrass using Illumina sequencing technology, we identified 670 known miRNA families from a total of more than 50 million short reads. A total of 273 miRNAs were identified with precursors: 126 conserved miRNAs and 147 novel miRNAs. Of them, 265 miRNAs were found to have their opposite sequences (miRNA*) with 2-nt overhang on the 3' end. Of them, 194 were detected in switchgrass transcriptome sequences generated from 31 high-throughput RNA sequencing (RNA-Seq) data sets in NCBI. Many miRNAs were differentially or uniquely expressed during salinity or drought stress treatment. We also discovered 11 miRNA clusters containing 29 miRNAs. These identified miRNAs potentially targeted 28549 genes with a various function, including transcription factors, stress-response proteins and cellulose biosynthesis-related proteins. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that the identified miRNAs and their targets were classified to 3779 GO terms including 1534 molecular functions, 1851 biological processes and 394 cellular components and were enriched to 147 KEGG pathways. Interestingly, 195 miRNA families and 450 targets were involved in the biosynthesis pathways of carbon, glucose, starch, fatty acid and lignin and in xylem formation, which could aid in designing next-generation switchgrass for biomass and biofuel.
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Affiliation(s)
- Fuliang Xie
- Department of Biology, East Carolina University, Greenville, NC, USA
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Sandoval PY, Swart EC, Arambasic M, Nowacki M. Functional diversification of Dicer-like proteins and small RNAs required for genome sculpting. Dev Cell 2014; 28:174-88. [PMID: 24439910 DOI: 10.1016/j.devcel.2013.12.010] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2013] [Revised: 11/04/2013] [Accepted: 12/17/2013] [Indexed: 12/15/2022]
Abstract
In eukaryotes, small RNAs (sRNAs) have key roles in development, gene expression regulation, and genome integrity maintenance. In ciliates, such as Paramecium, sRNAs form the heart of an epigenetic system that has evolved from core eukaryotic gene silencing components to selectively target DNA for deletion. In Paramecium, somatic genome development from the germline genome accurately eliminates the bulk of typically gene-interrupting, noncoding DNA. We have discovered an sRNA class (internal eliminated sequence [IES] sRNAs [iesRNAs]), arising later during Paramecium development, which originates from and precisely delineates germline DNA (IESs) and complements the initial sRNAs ("scan" RNAs [scnRNAs]) in targeting DNA for elimination. We show that whole-genome duplications have facilitated successive differentiations of Paramecium Dicer-like proteins, leading to cooperation between Dcl2 and Dcl3 to produce scnRNAs and to the production of iesRNAs by Dcl5. These innovations highlight the ability of sRNA systems to acquire capabilities, including those in genome development and integrity.
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Affiliation(s)
- Pamela Y Sandoval
- Institute of Cell Biology, University of Bern, Baltzerstrasse 4, Bern 3012, Switzerland
| | - Estienne C Swart
- Institute of Cell Biology, University of Bern, Baltzerstrasse 4, Bern 3012, Switzerland
| | - Miroslav Arambasic
- Institute of Cell Biology, University of Bern, Baltzerstrasse 4, Bern 3012, Switzerland
| | - Mariusz Nowacki
- Institute of Cell Biology, University of Bern, Baltzerstrasse 4, Bern 3012, Switzerland.
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47
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Clark JP, Lau NC. Piwi Proteins and piRNAs step onto the systems biology stage. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 825:159-97. [PMID: 25201106 PMCID: PMC4248790 DOI: 10.1007/978-1-4939-1221-6_5] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Animal germ cells are totipotent because they maintain a highly unique and specialized epigenetic state for its genome. To accomplish this, germ cells express a rich repertoire of specialized RNA-binding protein complexes such as the Piwi proteins and Piwi-interacting RNAs (piRNAs): a germ-cell branch of the RNA interference (RNAi) phenomenon which includes microRNA and endogenous small interfering RNA pathways. Piwi proteins and piRNAs are deeply conserved in animal evolution and play essential roles in fertility and regeneration. Molecular mechanisms for how these ribonucleoproteins act upon the transcriptome and genome are only now coming to light with the application of systems-wide approaches in both invertebrates and vertebrates. Systems biology studies on invertebrates have revealed that transcriptional and heritable silencing is a main mechanism driven by Piwi proteins and piRNA complexes. In vertebrates, Piwi-targeting mechanisms and piRNA biogenesis have progressed, while the discovery that the nuclease activity of Piwi protein is essential for vertebrate germ cell development but not completely required in invertebrates highlights the many complexities of this pathway in different animals. This review recounts how recent systems-wide approaches have rapidly accelerated our appreciation for the broad reach of the Piwi pathway on germline genome regulation and what questions facing the field await to be unraveled.
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Affiliation(s)
- Josef P. Clark
- Department of Biology and Rosenstiel Biomedical Research Center, Brandeis University, 415 South Street, Waltham, MA 02454, USA
| | - Nelson C. Lau
- Department of Biology and Rosenstiel Biomedical Research Center, Brandeis University, 415 South Street, Waltham, MA 02454, USA
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48
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Feng X, Guang S. Non-coding RNAs mediate the rearrangements of genomic DNA in ciliates. SCIENCE CHINA-LIFE SCIENCES 2013; 56:937-43. [PMID: 24008384 DOI: 10.1007/s11427-013-4539-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Accepted: 08/10/2013] [Indexed: 01/24/2023]
Abstract
Most eukaryotes employ a variety of mechanisms to defend the integrity of their genome by recognizing and silencing parasitic mobile nucleic acids. However, recent studies have shown that genomic DNA undergoes extensive rearrangements, including DNA elimination, fragmentation, and unscrambling, during the sexual reproduction of ciliated protozoa. Non-coding RNAs have been identified to program and regulate genome rearrangement events. In Paramecium and Tetrahymena, scan RNAs (scnRNAs) are produced from micronuclei and transported to vegetative macronuclei, in which scnRNA elicits the elimination of cognate genomic DNA. In contrast, Piwi-interacting RNAs (piRNAs) in Oxytricha enable the retention of genomic DNA that exhibits sequence complementarity in macronuclei. An RNA interference (RNAi)-like mechanism has been found to direct these genomic rearrangements. Furthermore, in Oxytricha, maternal RNA templates can guide the unscrambling process of genomic DNA. The non-coding RNA-directed genome rearrangements may have profound evolutionary implications, for example, eliciting the multigenerational inheritance of acquired adaptive traits.
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Affiliation(s)
- Xuezhu Feng
- School of Life Sciences, University of Science and Technology of China, Hefei, 230027, China
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Mochizuki K, Kurth HM. Loading and pre-loading processes generate a distinct siRNA population in Tetrahymena. Biochem Biophys Res Commun 2013; 436:497-502. [PMID: 23770361 PMCID: PMC3714595 DOI: 10.1016/j.bbrc.2013.05.133] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2013] [Accepted: 05/30/2013] [Indexed: 12/04/2022]
Abstract
The various properties of small RNAs, such as length, terminal nucleotide, thermodynamic asymmetry and duplex mismatches, can impact their sorting into different Argonaute proteins in diverse eukaryotes. The developmentally regulated 26- to 32-nt siRNAs (scnRNAs) are loaded to the Argonaute protein Twi1p and display a strong bias for uracil at the 5′ end. In this study, we used deep sequencing to analyze loaded and unloaded populations of scnRNAs. We show that the size of the scnRNA is determined during a pre-loading process, whereas their 5′ uracil bias is attributed to both pre-loading and loading processes. We also demonstrate that scnRNAs have a strong bias for adenine at the third base from the 3′ terminus, suggesting that most scnRNAs are direct Dicer products. Furthermore, we show that the thermodynamic asymmetry of the scnRNA duplex does not affect the guide and passenger strand decision. Finally, we show that scnRNAs frequently have templated uracil at the last base without a strong bias for adenine at the second base indicating non-sequential production of scnRNAs from substrates. These findings provide a biochemical basis for the varying attributes of scnRNAs, which should help improve our understanding of the production and turnover of scnRNAs in vivo.
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Affiliation(s)
- Kazufumi Mochizuki
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences, Dr. Bohr-Gasse 3, A-1030 Vienna, Austria.
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50
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Fang W, Wang X, Bracht JR, Nowacki M, Landweber LF. Piwi-interacting RNAs protect DNA against loss during Oxytricha genome rearrangement. Cell 2013; 151:1243-55. [PMID: 23217708 DOI: 10.1016/j.cell.2012.10.045] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2012] [Revised: 08/19/2012] [Accepted: 10/04/2012] [Indexed: 10/27/2022]
Abstract
Genome duality in ciliated protozoa offers a unique system to showcase their epigenome as a model of inheritance. In Oxytricha, the somatic genome is responsible for vegetative growth, whereas the germline contributes DNA to the next sexual generation. Somatic nuclear development removes all transposons and other so-called "junk" DNA, which comprise ~95% of the germline. We demonstrate that Piwi-interacting small RNAs (piRNAs) from the maternal nucleus can specify genomic regions for retention in this process. Oxytricha piRNAs map primarily to the somatic genome, representing the ~5% of the germline that is retained. Furthermore, injection of synthetic piRNAs corresponding to normally deleted regions leads to their retention in later generations. Our findings highlight small RNAs as powerful transgenerational carriers of epigenetic information for genome programming.
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Affiliation(s)
- Wenwen Fang
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
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