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van Lopik J, Alizada A, Trapotsi MA, Hannon GJ, Bornelöv S, Czech Nicholson B. Unistrand piRNA clusters are an evolutionarily conserved mechanism to suppress endogenous retroviruses across the Drosophila genus. Nat Commun 2023; 14:7337. [PMID: 37957172 PMCID: PMC10643416 DOI: 10.1038/s41467-023-42787-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Accepted: 10/18/2023] [Indexed: 11/15/2023] Open
Abstract
The PIWI-interacting RNA (piRNA) pathway prevents endogenous genomic parasites, i.e. transposable elements, from damaging the genetic material of animal gonadal cells. Specific regions in the genome, called piRNA clusters, are thought to define each species' piRNA repertoire and therefore its capacity to recognize and silence specific transposon families. The unistrand cluster flamenco (flam) is essential in the somatic compartment of the Drosophila ovary to restrict Gypsy-family transposons from infecting the neighbouring germ cells. Disruption of flam results in transposon de-repression and sterility, yet it remains unknown whether this silencing mechanism is present more widely. Here, we systematically characterise 119 Drosophila species and identify five additional flam-like clusters separated by up to 45 million years of evolution. Small RNA-sequencing validated these as bona-fide unistrand piRNA clusters expressed in somatic cells of the ovary, where they selectively target transposons of the Gypsy family. Together, our study provides compelling evidence of a widely conserved transposon silencing mechanism that co-evolved with virus-like Gypsy-family transposons.
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Affiliation(s)
- Jasper van Lopik
- Cancer Research UK Cambridge Institute, University of Cambridge, Li Ka Shing Centre, Cambridge, CB2 0RE, UK
| | - Azad Alizada
- Cancer Research UK Cambridge Institute, University of Cambridge, Li Ka Shing Centre, Cambridge, CB2 0RE, UK
| | - Maria-Anna Trapotsi
- Cancer Research UK Cambridge Institute, University of Cambridge, Li Ka Shing Centre, Cambridge, CB2 0RE, UK
| | - Gregory J Hannon
- Cancer Research UK Cambridge Institute, University of Cambridge, Li Ka Shing Centre, Cambridge, CB2 0RE, UK
| | - Susanne Bornelöv
- Cancer Research UK Cambridge Institute, University of Cambridge, Li Ka Shing Centre, Cambridge, CB2 0RE, UK.
| | - Benjamin Czech Nicholson
- Cancer Research UK Cambridge Institute, University of Cambridge, Li Ka Shing Centre, Cambridge, CB2 0RE, UK.
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2
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Wierzbicki F, Kofler R. The composition of piRNA clusters in Drosophila melanogaster deviates from expectations under the trap model. BMC Biol 2023; 21:224. [PMID: 37858221 PMCID: PMC10588112 DOI: 10.1186/s12915-023-01727-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Accepted: 10/06/2023] [Indexed: 10/21/2023] Open
Abstract
BACKGROUND It is widely assumed that the invasion of a transposable element (TE) in mammals and invertebrates is stopped when a copy of the TE jumps into a piRNA cluster (i.e., the trap model). However, recent works, which for example showed that deletion of three major piRNA clusters has no effect on TE activity, cast doubt on the trap model. RESULTS Here, we test the trap model from a population genetics perspective. Our simulations show that the composition of regions that act as transposon traps (i.e., potentially piRNA clusters) ought to deviate from regions that have no effect on TE activity. We investigated TEs in five Drosophila melanogaster strains using three complementary approaches to test whether the composition of piRNA clusters matches these expectations. We found that the abundance of TE families inside and outside of piRNA clusters is highly correlated, although this is not expected under the trap model. Furthermore, the distribution of the number of TE insertions in piRNA clusters is also much broader than expected. CONCLUSIONS We found that the observed composition of piRNA clusters is not in agreement with expectations under the simple trap model. Dispersed piRNA producing TE insertions and temporal as well as spatial heterogeneity of piRNA clusters may account for these deviations.
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Affiliation(s)
- Filip Wierzbicki
- Institut für Populationsgenetik, Vetmeduni Vienna, Vienna, Austria
- Vienna Graduate School of Population Genetics, Vienna, Austria
| | - Robert Kofler
- Institut für Populationsgenetik, Vetmeduni Vienna, Vienna, Austria.
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Yoth M, Maupetit-Méhouas S, Akkouche A, Gueguen N, Bertin B, Jensen S, Brasset E. Reactivation of a somatic errantivirus and germline invasion in Drosophila ovaries. Nat Commun 2023; 14:6096. [PMID: 37773253 PMCID: PMC10541861 DOI: 10.1038/s41467-023-41733-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Accepted: 09/15/2023] [Indexed: 10/01/2023] Open
Abstract
Most Drosophila transposable elements are LTR retrotransposons, some of which belong to the genus Errantivirus and share structural and functional characteristics with vertebrate endogenous retroviruses. Like endogenous retroviruses, it is unclear whether errantiviruses retain some infectivity and transposition capacity. We created conditions where control of the Drosophila ZAM errantivirus through the piRNA pathway was abolished leading to its de novo reactivation in somatic gonadal cells. After reactivation, ZAM invaded the oocytes and severe fertility defects were observed. While ZAM expression persists in the somatic gonadal cells, the germline then set up its own adaptive genomic immune response by producing piRNAs against the constantly invading errantivirus, restricting invasion. Our results suggest that although errantiviruses are continuously repressed by the piRNA pathway, they may retain their ability to infect the germline and transpose, thus allowing them to efficiently invade the germline if they are expressed.
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Affiliation(s)
- Marianne Yoth
- iGReD, Université Clermont Auvergne, CNRS, INSERM, Faculté de Médecine, 63000, Clermont-Ferrand, France
| | | | - Abdou Akkouche
- iGReD, Université Clermont Auvergne, CNRS, INSERM, Faculté de Médecine, 63000, Clermont-Ferrand, France
| | - Nathalie Gueguen
- iGReD, Université Clermont Auvergne, CNRS, INSERM, Faculté de Médecine, 63000, Clermont-Ferrand, France
| | - Benjamin Bertin
- LIMAGRAIN EUROPE, Centre de recherche, 63720, Chappes, France
| | - Silke Jensen
- iGReD, Université Clermont Auvergne, CNRS, INSERM, Faculté de Médecine, 63000, Clermont-Ferrand, France.
| | - Emilie Brasset
- iGReD, Université Clermont Auvergne, CNRS, INSERM, Faculté de Médecine, 63000, Clermont-Ferrand, France.
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Signor S, Vedanayagam J, Kim BY, Wierzbicki F, Kofler R, Lai EC. Rapid evolutionary diversification of the flamenco locus across simulans clade Drosophila species. PLoS Genet 2023; 19:e1010914. [PMID: 37643184 PMCID: PMC10495008 DOI: 10.1371/journal.pgen.1010914] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 09/11/2023] [Accepted: 08/09/2023] [Indexed: 08/31/2023] Open
Abstract
Suppression of transposable elements (TEs) is paramount to maintain genomic integrity and organismal fitness. In D. melanogaster, the flamenco locus is a master suppressor of TEs, preventing the mobilization of certain endogenous retrovirus-like TEs from somatic ovarian support cells to the germline. It is transcribed by Pol II as a long (100s of kb), single-stranded, primary transcript, and metabolized into ~24-32 nt Piwi-interacting RNAs (piRNAs) that target active TEs via antisense complementarity. flamenco is thought to operate as a trap, owing to its high content of recent horizontally transferred TEs that are enriched in antisense orientation. Using newly-generated long read genome data, which is critical for accurate assembly of repetitive sequences, we find that flamenco has undergone radical transformations in sequence content and even copy number across simulans clade Drosophilid species. Drosophila simulans flamenco has duplicated and diverged, and neither copy exhibits synteny with D. melanogaster beyond the core promoter. Moreover, flamenco organization is highly variable across D. simulans individuals. Next, we find that D. simulans and D. mauritiana flamenco display signatures of a dual-stranded cluster, with ping-pong signals in the testis and/or embryo. This is accompanied by increased copy numbers of germline TEs, consistent with these regions operating as functional dual-stranded clusters. Overall, the physical and functional diversity of flamenco orthologs is testament to the extremely dynamic consequences of TE arms races on genome organization, not only amongst highly related species, but even amongst individuals.
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Affiliation(s)
- Sarah Signor
- Biological Sciences, North Dakota State University, Fargo, North Dakota, United States of America
| | - Jeffrey Vedanayagam
- Developmental Biology Program, Sloan-Kettering Institute, New York, New York, United States of America
- Department of Neuroscience, Developmental and Regenerative Biology, University of Texas at San Antonio, Texas, United States of America
| | - Bernard Y. Kim
- Department of Biology, Stanford University, Stanford, California, United States of America
| | - Filip Wierzbicki
- Institut für Populationsgenetik, Vetmeduni Vienna, Vienna, Austria
- Vienna Graduate School of Population Genetics, Vienna, Austria
| | - Robert Kofler
- Institut für Populationsgenetik, Vetmeduni Vienna, Vienna, Austria
| | - Eric C. Lai
- Developmental Biology Program, Sloan-Kettering Institute, New York, New York, United States of America
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Chen J, Basting PJ, Han S, Garfinkel DJ, Bergman CM. Reproducible evaluation of transposable element detectors with McClintock 2 guides accurate inference of Ty insertion patterns in yeast. Mob DNA 2023; 14:8. [PMID: 37452430 PMCID: PMC10347736 DOI: 10.1186/s13100-023-00296-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2023] [Accepted: 06/09/2023] [Indexed: 07/18/2023] Open
Abstract
BACKGROUND Many computational methods have been developed to detect non-reference transposable element (TE) insertions using short-read whole genome sequencing data. The diversity and complexity of such methods often present challenges to new users seeking to reproducibly install, execute, or evaluate multiple TE insertion detectors. RESULTS We previously developed the McClintock meta-pipeline to facilitate the installation, execution, and evaluation of six first-generation short-read TE detectors. Here, we report a completely re-implemented version of McClintock written in Python using Snakemake and Conda that improves its installation, error handling, speed, stability, and extensibility. McClintock 2 now includes 12 short-read TE detectors, auxiliary pre-processing and analysis modules, interactive HTML reports, and a simulation framework to reproducibly evaluate the accuracy of component TE detectors. When applied to the model microbial eukaryote Saccharomyces cerevisiae, we find substantial variation in the ability of McClintock 2 components to identify the precise locations of non-reference TE insertions, with RelocaTE2 showing the highest recall and precision in simulated data. We find that RelocaTE2, TEMP, TEMP2 and TEBreak provide consistent estimates of [Formula: see text]50 non-reference TE insertions per strain and that Ty2 has the highest number of non-reference TE insertions in a species-wide panel of [Formula: see text]1000 yeast genomes. Finally, we show that best-in-class predictors for yeast applied to resequencing data have sufficient resolution to reveal a dyad pattern of integration in nucleosome-bound regions upstream of yeast tRNA genes for Ty1, Ty2, and Ty4, allowing us to extend knowledge about fine-scale target preferences revealed previously for experimentally-induced Ty1 insertions to spontaneous insertions for other copia-superfamily retrotransposons in yeast. CONCLUSION McClintock ( https://github.com/bergmanlab/mcclintock/ ) provides a user-friendly pipeline for the identification of TEs in short-read WGS data using multiple TE detectors, which should benefit researchers studying TE insertion variation in a wide range of different organisms. Application of the improved McClintock system to simulated and empirical yeast genome data reveals best-in-class methods and novel biological insights for one of the most widely-studied model eukaryotes and provides a paradigm for evaluating and selecting non-reference TE detectors in other species.
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Affiliation(s)
- Jingxuan Chen
- Institute of Bioinformatics, University of Georgia, Athens, GA USA
| | | | - Shunhua Han
- Institute of Bioinformatics, University of Georgia, Athens, GA USA
| | - David J. Garfinkel
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA USA
| | - Casey M. Bergman
- Institute of Bioinformatics, University of Georgia, Athens, GA USA
- Department of Genetics, University of Georgia, Athens, GA USA
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Asif-Laidin A, Casier K, Ziriat Z, Boivin A, Viodé E, Delmarre V, Ronsseray S, Carré C, Teysset L. Modeling early germline immunization after horizontal transfer of transposable elements reveals internal piRNA cluster heterogeneity. BMC Biol 2023; 21:117. [PMID: 37226160 DOI: 10.1186/s12915-023-01616-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Accepted: 05/05/2023] [Indexed: 05/26/2023] Open
Abstract
BACKGROUND A fraction of all genomes is composed of transposable elements (TEs) whose mobility needs to be carefully controlled. In gonads, TE activity is repressed by PIWI-interacting RNAs (piRNAs), a class of small RNAs synthesized by heterochromatic loci enriched in TE fragments, called piRNA clusters. Maintenance of active piRNA clusters across generations is secured by maternal piRNA inheritance providing the memory for TE repression. On rare occasions, genomes encounter horizontal transfer (HT) of new TEs with no piRNA targeting them, threatening the host genome integrity. Naïve genomes can eventually start to produce new piRNAs against these genomic invaders, but the timing of their emergence remains elusive. RESULTS Using a set of TE-derived transgenes inserted in different germline piRNA clusters and functional assays, we have modeled a TE HT in Drosophila melanogaster. We have found that the complete co-option of these transgenes by a germline piRNA cluster can occur within four generations associated with the production of new piRNAs all along the transgenes and the germline silencing of piRNA sensors. Synthesis of new transgenic TE piRNAs is linked to piRNA cluster transcription dependent on Moonshiner and heterochromatin mark deposition that propagates more efficiently on short sequences. Moreover, we found that sequences located within piRNA clusters can have different piRNA profiles and can influence transcript accumulation of nearby sequences. CONCLUSIONS Our study reveals that genetic and epigenetic properties, such as transcription, piRNA profiles, heterochromatin, and conversion efficiency along piRNA clusters, could be heterogeneous depending on the sequences that compose them. These findings suggest that the capacity of transcriptional signal erasure induced by the chromatin complex specific of the piRNA cluster can be incomplete through the piRNA cluster loci. Finally, these results have revealed an unexpected level of complexity that highlights a new magnitude of piRNA cluster plasticity fundamental for the maintenance of genome integrity.
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Affiliation(s)
- Amna Asif-Laidin
- Sorbonne Université, CNRS, Institut de Biologie Paris-Seine, Laboratoire Biologie du Développement, UMR7622, "Transgenerational Epigenetics & Small RNA Biology", Paris, F-75005, France
| | - Karine Casier
- Sorbonne Université, CNRS, Institut de Biologie Paris-Seine, Laboratoire Biologie du Développement, UMR7622, "Transgenerational Epigenetics & Small RNA Biology", Paris, F-75005, France
- Present Address: CNRS, Institut de Biologie Physico-Chimique, Laboratoire de Biologie Moléculaire et Cellulaire des Eucaryotes, UMR8226, Telomere Biology, Paris, F-75005, France
| | - Zoheir Ziriat
- Sorbonne Université, CNRS, Institut de Biologie Paris-Seine, Laboratoire Biologie du Développement, UMR7622, "Transgenerational Epigenetics & Small RNA Biology", Paris, F-75005, France
| | - Antoine Boivin
- Sorbonne Université, CNRS, Institut de Biologie Paris-Seine, Laboratoire Biologie du Développement, UMR7622, "Transgenerational Epigenetics & Small RNA Biology", Paris, F-75005, France
| | - Elise Viodé
- Sorbonne Université, CNRS, Institut de Biologie Paris-Seine, Laboratoire Biologie du Développement, UMR7622, "Transgenerational Epigenetics & Small RNA Biology", Paris, F-75005, France
| | - Valérie Delmarre
- Sorbonne Université, CNRS, Institut de Biologie Paris-Seine, Laboratoire Biologie du Développement, UMR7622, "Transgenerational Epigenetics & Small RNA Biology", Paris, F-75005, France
| | - Stéphane Ronsseray
- Sorbonne Université, CNRS, Institut de Biologie Paris-Seine, Laboratoire Biologie du Développement, UMR7622, "Transgenerational Epigenetics & Small RNA Biology", Paris, F-75005, France
| | - Clément Carré
- Sorbonne Université, CNRS, Institut de Biologie Paris-Seine, Laboratoire Biologie du Développement, UMR7622, "Transgenerational Epigenetics & Small RNA Biology", Paris, F-75005, France
| | - Laure Teysset
- Sorbonne Université, CNRS, Institut de Biologie Paris-Seine, Laboratoire Biologie du Développement, UMR7622, "Transgenerational Epigenetics & Small RNA Biology", Paris, F-75005, France.
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Santos D, Feng M, Kolliopoulou A, Taning CNT, Sun J, Swevers L. What Are the Functional Roles of Piwi Proteins and piRNAs in Insects? Insects 2023; 14:insects14020187. [PMID: 36835756 PMCID: PMC9962485 DOI: 10.3390/insects14020187] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2023] [Revised: 02/09/2023] [Accepted: 02/11/2023] [Indexed: 06/01/2023]
Abstract
Research on Piwi proteins and piRNAs in insects has focused on three experimental models: oogenesis and spermatogenesis in Drosophila melanogaster, the antiviral response in Aedes mosquitoes and the molecular analysis of primary and secondary piRNA biogenesis in Bombyx mori-derived BmN4 cells. Significant unique and complementary information has been acquired and has led to a greater appreciation of the complexity of piRNA biogenesis and Piwi protein function. Studies performed in other insect species are emerging and promise to add to the current state of the art on the roles of piRNAs and Piwi proteins. Although the primary role of the piRNA pathway is genome defense against transposons, particularly in the germline, recent findings also indicate an expansion of its functions. In this review, an extensive overview is presented of the knowledge of the piRNA pathway that so far has accumulated in insects. Following a presentation of the three major models, data from other insects were also discussed. Finally, the mechanisms for the expansion of the function of the piRNA pathway from transposon control to gene regulation were considered.
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Affiliation(s)
- Dulce Santos
- Research Group of Molecular Developmental Physiology and Signal Transduction, Division of Animal Physiology and Neurobiology, Department of Biology, KU Leuven, Naamsestraat 59, 3000 Leuven, Belgium
| | - Min Feng
- Guangdong Provincial Key Laboratory of Agro-Animal Genomics and Molecular Breeding, College of Animal Science, South China Agricultural University, Guangzhou 510642, China
| | - Anna Kolliopoulou
- Insect Molecular Genetics and Biotechnology, Institute of Biosciences & Applications, National Centre for Scientific Research “Demokritos”, Aghia Paraskevi, 15341 Athens, Greece
| | - Clauvis N. T. Taning
- Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, 9000 Ghent, Belgium
| | - Jingchen Sun
- Guangdong Provincial Key Laboratory of Agro-Animal Genomics and Molecular Breeding, College of Animal Science, South China Agricultural University, Guangzhou 510642, China
| | - Luc Swevers
- Insect Molecular Genetics and Biotechnology, Institute of Biosciences & Applications, National Centre for Scientific Research “Demokritos”, Aghia Paraskevi, 15341 Athens, Greece
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Chen J, Basting PJ, Han S, Garfinkel DJ, Bergman CM. Reproducible evaluation of short-read transposable element detectors and species-wide data mining of insertion patterns in yeast. bioRxiv 2023:2023.02.13.528343. [PMID: 36824955 PMCID: PMC9948991 DOI: 10.1101/2023.02.13.528343] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
Abstract
Background Many computational methods have been developed to detect non-reference transposable element (TE) insertions using short-read whole genome sequencing data. The diversity and complexity of such methods often present challenges to new users seeking to reproducibly install, execute or evaluate multiple TE insertion detectors. Results We previously developed the McClintock meta-pipeline to facilitate the installation, execution, and evaluation of six first-generation short-read TE detectors. Here, we report a completely re-implemented version of McClintock written in Python using Snakemake and Conda that improves its installation, error handling, speed, stability, and extensibility. McClintock 2 now includes 12 short-read TE detectors, auxiliary pre-processing and analysis modules, interactive HTML reports, and a simulation framework to reproducibly evaluate the accuracy of component TE detectors. When applied to the model microbial eukaryote Saccharomyces cerevisiae , we find substantial variation in the ability of McClintock 2 components to identify the precise locations of non-reference TE insertions, with RelocaTE2 showing the highest recall and precision in simulated data. We find that RelocaTE2, TEMP, TEMP2 and TEBreak provide a consistent and biologically meaningful view of non-reference TE insertions in a species-wide panel of ∼ 1000 yeast genomes, as evaluated by coverage-based abundance estimates and expected patterns of tRNA promoter targeting. Finally, we show that best-in-class predictors for yeast have sufficient resolution to reveal a dyad pattern of integration in nucleosome-bound regions upstream of yeast tRNA genes for Ty1, Ty2, and Ty4, allowing us to extend knowledge aboutfine-scale target preferences first revealed experimentally for Ty1 to natural insertions and related copia -superfamily retrotransposons in yeast. Conclusion McClintock ( https://github.com/bergmanlab/mcclintock/ ) provides a user-friendly pipeline for the identification of TEs in short-read WGS data using multiple TE detectors, which should benefit researchers studying TE insertion variation in a wide range of different organisms. Application of the improved McClintock system to simulated and empirical yeast genome data reveals best-in-class methods and novel biological insights for one of the most widely-studied model eukaryotes and provides a paradigm for evaluating and selecting non-reference TE detectors for other species.
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Berger J, Legendre F, Zelosko KM, Harrison MC, Grandcolas P, Bornberg-Bauer E, Fouks B. Eusocial Transition in Blattodea: Transposable Elements and Shifts of Gene Expression. Genes (Basel) 2022; 13:1948. [PMID: 36360186 PMCID: PMC9689775 DOI: 10.3390/genes13111948] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Revised: 10/19/2022] [Accepted: 10/20/2022] [Indexed: 11/07/2023] Open
Abstract
(1) Unravelling the molecular basis underlying major evolutionary transitions can shed light on how complex phenotypes arise. The evolution of eusociality, a major evolutionary transition, has been demonstrated to be accompanied by enhanced gene regulation. Numerous pieces of evidence suggest the major impact of transposon insertion on gene regulation and its role in adaptive evolution. Transposons have been shown to be play a role in gene duplication involved in the eusocial transition in termites. However, evidence of the molecular basis underlying the eusocial transition in Blattodea remains scarce. Could transposons have facilitated the eusocial transition in termites through shifts of gene expression? (2) Using available cockroach and termite genomes and transcriptomes, we investigated if transposons insert more frequently in genes with differential expression in queens and workers and if those genes could be linked to specific functions essential for eusocial transition. (3) The insertion rate of transposons differs among differentially expressed genes and displays opposite trends between termites and cockroaches. The functions of termite transposon-rich queen- and worker-biased genes are related to reproduction and ageing and behaviour and gene expression, respectively. (4) Our study provides further evidence on the role of transposons in the evolution of eusociality, potentially through shifts in gene expression.
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Affiliation(s)
- Juliette Berger
- Institut de Systématique, Évolution, Biodiversité (ISYEB), Muséum National d’Histoire Naturelle, CNRS, Sorbonne Université, EPHE, Université des Antilles, CP50, 57 rue Cuvier, 75005 Paris, France
| | - Frédéric Legendre
- Institut de Systématique, Évolution, Biodiversité (ISYEB), Muséum National d’Histoire Naturelle, CNRS, Sorbonne Université, EPHE, Université des Antilles, CP50, 57 rue Cuvier, 75005 Paris, France
| | - Kevin-Markus Zelosko
- Institute for Evolution and Biodiversity, Molecular Evolution and Bioinformatics, Westfälische Wilhelms-Universität, Hüfferstrasse 1, 48149 Münster, Germany
| | - Mark C. Harrison
- Institute for Evolution and Biodiversity, Molecular Evolution and Bioinformatics, Westfälische Wilhelms-Universität, Hüfferstrasse 1, 48149 Münster, Germany
| | - Philippe Grandcolas
- Institut de Systématique, Évolution, Biodiversité (ISYEB), Muséum National d’Histoire Naturelle, CNRS, Sorbonne Université, EPHE, Université des Antilles, CP50, 57 rue Cuvier, 75005 Paris, France
| | - Erich Bornberg-Bauer
- Institute for Evolution and Biodiversity, Molecular Evolution and Bioinformatics, Westfälische Wilhelms-Universität, Hüfferstrasse 1, 48149 Münster, Germany
- Department of Protein Evolution, Max Planck Institute for Developmental Biology, Max-Planck-Ring 5, 72076 Tübingen, Germany
| | - Bertrand Fouks
- Institute for Evolution and Biodiversity, Molecular Evolution and Bioinformatics, Westfälische Wilhelms-Universität, Hüfferstrasse 1, 48149 Münster, Germany
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Solodovnikov A, Lavrov S. Exact breakpoints of the In(1)w m4 rearrangement. MicroPubl Biol 2022; 2022:10.17912/micropub.biology.000608. [PMID: 35903781 PMCID: PMC9315410 DOI: 10.17912/micropub.biology.000608] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Revised: 07/09/2022] [Accepted: 07/24/2022] [Indexed: 11/12/2022]
Abstract
In(1)w m4 has been known for decades as a classic example of a position effect variegation-causing rearrangement and has been mentioned in hundreds of publications. Nevertheless, its euchromatic breakpoint has not been localized with base-pair resolution. We performed nanopore sequencing of DNA from In(1)w m4 homozygous flies and determined the exact position of euchromatic (chrX:2767875) and heterochromatic breakpoints of the rearrangement. The heterochromatic breakpoint is located in an unlinked part of the genome in the region, enriched in TEs (transposable elements) fragments. A set of unique piRNAs could be detected in the region.
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Affiliation(s)
- Alexander Solodovnikov
- Institute of Molecular Genetics of National Research Centre, Kurchatov Institute, Moscow, RUS
| | - Sergey Lavrov
- Institute of Molecular Genetics of National Research Centre, Kurchatov Institute, Moscow, RUS
,
Correspondence to: Sergey Lavrov (
)
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11
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Abstract
The popular trap model assumes that the invasions of transposable elements (TEs) in mammals and invertebrates are stopped by piRNAs that emerge after insertion of the TE into a piRNA cluster. It remains, however, still unclear which factors influence the dynamics of TE invasions. The activity of the TE (i.e., transposition rate) is one frequently discussed key factor. Here we take advantage of the temperature-dependent activity of the P-element, a widely studied eukaryotic TE, to test how TE activity affects the dynamics of a TE invasion. We monitored P-element invasion dynamics in experimental Drosophila simulans populations at hot and cold culture conditions. Despite marked differences in transposition rates, the P-element reached very similar copy numbers at both temperatures. The reduction of the insertion rate upon approaching the copy number plateau was accompanied by similar amounts of piRNAs against the P-element at both temperatures. Nevertheless, we also observed fewer P-element insertions in piRNA clusters than expected, which is not compatible with a simple trap model. The ping-pong cycle, which degrades TE transcripts, becomes typically active after the copy number plateaued. We generated a model, with few parameters, that largely captures the observed invasion dynamics. We conclude that the transposition rate has at the most only a minor influence on TE abundance, but other factors, such as paramutations or selection against TE insertions are shaping the TE composition.
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Affiliation(s)
- Robert Kofler
- Institut für Populationsgenetik, Vetmeduni Vienna, Veterinärplatz 1, 1210 Wien, Austria
| | - Viola Nolte
- Institut für Populationsgenetik, Vetmeduni Vienna, Veterinärplatz 1, 1210 Wien, Austria
| | - Christian Schlötterer
- Institut für Populationsgenetik, Vetmeduni Vienna, Veterinärplatz 1, 1210 Wien, Austria
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12
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Yoth M, Jensen S, Brasset E. The Intricate Evolutionary Balance between Transposable Elements and Their Host: Who Will Kick at Goal and Convert the Next Try? Biology (Basel) 2022; 11:710. [PMID: 35625438 PMCID: PMC9138309 DOI: 10.3390/biology11050710] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Revised: 04/15/2022] [Accepted: 04/26/2022] [Indexed: 11/29/2022]
Abstract
Transposable elements (TEs) are mobile DNA sequences that can jump from one genomic locus to another and that have colonized the genomes of all living organisms. TE mobilization and accumulation are an important source of genomic innovations that greatly contribute to the host species evolution. To ensure their maintenance and amplification, TE transposition must occur in the germ cell genome. As TE transposition is also a major threat to genome integrity, the outcome of TE mobility in germ cell genomes could be highly dangerous because such mutations are inheritable. Thus, organisms have developed specialized strategies to protect the genome integrity from TE transposition, particularly in germ cells. Such effective TE silencing, together with ongoing mutations and negative selection, should result in the complete elimination of functional TEs from genomes. However, TEs have developed efficient strategies for their maintenance and spreading in populations, particularly by using horizontal transfer to invade the genome of novel species. Here, we discuss how TEs manage to bypass the host's silencing machineries to propagate in its genome and how hosts engage in a fightback against TE invasion and propagation. This shows how TEs and their hosts have been evolving together to achieve a fine balance between transposition and repression.
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Affiliation(s)
| | | | - Emilie Brasset
- iGReD, CNRS, INSERM, Faculté de Médecine, Université Clermont Auvergne, 63000 Clermont-Ferrand, France; (M.Y.); (S.J.)
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13
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Cerqueira de Araujo A, Huguet E, Herniou EA, Drezen JM, Josse T. Transposable element repression using piRNAs, and its relevance to endogenous viral elements (EVEs) and immunity in insects. Curr Opin Insect Sci 2022; 50:100876. [PMID: 35065285 DOI: 10.1016/j.cois.2022.100876] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Revised: 01/07/2022] [Accepted: 01/13/2022] [Indexed: 06/14/2023]
Abstract
The piRNA system controls transposable element (TE) mobility by transcriptional gene silencing and post-transcriptional gene silencing. Dispersed in insect genomes, piRNA clusters contain TE copies, from which they produce piRNAs (specific small RNAs). These piRNAs can both target the nascent transcripts produced by active TE copies and directly repress them by heterochromatinization. They can also target mature transcripts and cleave them following amplification by the so-called 'ping-pong' loop mechanism. Moreover, piRNA clusters contain endogenous viral elements (EVEs), from which they produce piRNAs. The current idea is that these piRNAs could participate in the antiviral response against exogenous viral infection. In this review, we show that among insects, to date, this antiviral response by the piRNA system appears mainly restricted to mosquitoes, but this could be due to the focus of most studies on arboviruses.
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Affiliation(s)
- Alexandra Cerqueira de Araujo
- Institut de Recherche sur la Biologie de l'Insecte (IRBI), UMR 7261, CNRS - Université de Tours, 37200 Tours, France
| | - Elisabeth Huguet
- Institut de Recherche sur la Biologie de l'Insecte (IRBI), UMR 7261, CNRS - Université de Tours, 37200 Tours, France
| | - Elisabeth A Herniou
- Institut de Recherche sur la Biologie de l'Insecte (IRBI), UMR 7261, CNRS - Université de Tours, 37200 Tours, France
| | - Jean-Michel Drezen
- Institut de Recherche sur la Biologie de l'Insecte (IRBI), UMR 7261, CNRS - Université de Tours, 37200 Tours, France
| | - Thibaut Josse
- Institut de Recherche sur la Biologie de l'Insecte (IRBI), UMR 7261, CNRS - Université de Tours, 37200 Tours, France.
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14
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Wang ZZ, Ye XQ, Huang JH, Chen XX. Virus and endogenous viral element-derived small non-coding RNAs and their roles in insect-virus interaction. Curr Opin Insect Sci 2022; 49:85-92. [PMID: 34974161 DOI: 10.1016/j.cois.2021.12.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 12/20/2021] [Accepted: 12/21/2021] [Indexed: 06/14/2023]
Abstract
RNA interference pathways mediated by different types of small non-coding RNAs (siRNAs, miRNAs and piRNAs) are conserved biological responses to exotic stresses, including viral infection. Aside from the well-established siRNA pathway, the miRNA pathway and the piRNA pathway process viral sequences, exogenously or endogenously, into miRNAs and piRNAs, respectively. During the host-virus interaction, viral sequences, including both coding and non-coding sequences, can be integrated as endogenous viral elements (EVEs) and thereby become present within the germline of a non-viral organism. In recent years, significant progress has been made in characterizing the biogenesis and function of viruses and EVEs associated with snRNAs. Overall, the siRNA pathway acts as the primarily antiviral defense against a wide range of exogenous viruses; the miRNA pathways associated with viruses or EVEs function in antiviral response and host gene regulation; EVE derived piRNAs with a ping-pong signature have the potential to limit cognate viral infection.
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Affiliation(s)
- Zhi-Zhi Wang
- Institute of Insect Sciences, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 310058, China; Ministry of Agriculture Key Lab of Molecular Biology of Crop Pathogens and Insect Pests, Zhejiang University, Hangzhou 310058, China; Key Laboratory of Biology of Crop Pathogens and Insects of Zhejiang Province, Zhejiang University, Hangzhou 310058, China
| | - Xi-Qian Ye
- Institute of Insect Sciences, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 310058, China; Ministry of Agriculture Key Lab of Molecular Biology of Crop Pathogens and Insect Pests, Zhejiang University, Hangzhou 310058, China; Key Laboratory of Biology of Crop Pathogens and Insects of Zhejiang Province, Zhejiang University, Hangzhou 310058, China
| | - Jian-Hua Huang
- Institute of Insect Sciences, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 310058, China; Ministry of Agriculture Key Lab of Molecular Biology of Crop Pathogens and Insect Pests, Zhejiang University, Hangzhou 310058, China; Key Laboratory of Biology of Crop Pathogens and Insects of Zhejiang Province, Zhejiang University, Hangzhou 310058, China
| | - Xue-Xin Chen
- Institute of Insect Sciences, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 310058, China; Ministry of Agriculture Key Lab of Molecular Biology of Crop Pathogens and Insect Pests, Zhejiang University, Hangzhou 310058, China; Key Laboratory of Biology of Crop Pathogens and Insects of Zhejiang Province, Zhejiang University, Hangzhou 310058, China; State Key Lab of Rice Biology, Zhejiang University, Hangzhou 310058, China.
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15
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Wierzbicki F, Schwarz F, Cannalonga O, Kofler R. Novel quality metrics allow identifying and generating high-quality assemblies of piRNA clusters. Mol Ecol Resour 2022; 22:102-121. [PMID: 34181811 DOI: 10.1111/1755-0998.13455] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 04/30/2021] [Accepted: 06/14/2021] [Indexed: 12/30/2022]
Abstract
In most animals, it is thought that the proliferation of a transposable element (TE) is stopped when the TE jumps into a piRNA cluster. Despite this central importance, little is known about the composition and the evolutionary dynamics of piRNA clusters. This is largely because piRNA clusters are notoriously difficult to assemble as they are frequently composed of highly repetitive DNA. With long reads, we may finally be able to obtain reliable assemblies of piRNA clusters. Unfortunately, it is unclear how to generate and identify the best assemblies, as many assembly strategies exist and standard quality metrics are ignorant of TEs. To address these problems, we introduce several novel quality metrics that assess: (a) the fraction of completely assembled piRNA clusters, (b) the quality of the assembled clusters and (c) whether an assembly captures the overall TE landscape of an organisms (i.e. the abundance, the number of SNPs and internal deletions of all TE families). The requirements for computing these metrics vary, ranging from annotations of piRNA clusters to consensus sequences of TEs and genomic sequencing data. Using these novel metrics, we evaluate the effect of assembly algorithm, polishing, read length, coverage, residual polymorphisms and finally identify strategies that yield reliable assemblies of piRNA clusters. Based on an optimized approach, we provide assemblies for the two Drosophila melanogaster strains Canton-S and Pi2. About 80% of known piRNA clusters were assembled in both strains. Finally, we demonstrate the generality of our approach by extending our metrics to humans and Arabidopsis thaliana.
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Affiliation(s)
- Filip Wierzbicki
- Institut für Populationsgenetik, Vetmeduni Vienna, Wien, Austria.,Vienna Graduate School of Population Genetics, Vetmeduni Vienna, Vienna, Austria
| | - Florian Schwarz
- Institut für Populationsgenetik, Vetmeduni Vienna, Wien, Austria.,Vienna Graduate School of Population Genetics, Vetmeduni Vienna, Vienna, Austria
| | | | - Robert Kofler
- Institut für Populationsgenetik, Vetmeduni Vienna, Wien, Austria
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16
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Giordani G, Cavaliere V, Gargiulo G, Lattanzi G, Andrenacci D. Retrotransposons Down- and Up-Regulation in Aging Somatic Tissues. Cells 2021; 11:79. [PMID: 35011640 DOI: 10.3390/cells11010079] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Revised: 12/22/2021] [Accepted: 12/26/2021] [Indexed: 01/19/2023] Open
Abstract
The transposon theory of aging hypothesizes the activation of transposable elements (TEs) in somatic tissues with age, leading to a shortening of the lifespan. It is thought that TE activation in aging produces an increase in DNA double-strand breaks, contributing to genome instability and promoting the activation of inflammatory responses. To investigate how TE regulation changes in somatic tissues during aging, we analyzed the expression of some TEs, as well as a source of small RNAs that specifically silence the analyzed TEs; the Drosophila cluster named flamenco. We found significant variations in the expression levels of all the analyzed TEs during aging, with a trend toward reduction in middle-aged adults and reactivation in older individuals that suggests dynamic regulation during the lifespan.
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17
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Gebert D, Neubert LK, Lloyd C, Gui J, Lehmann R, Teixeira FK. Large Drosophila germline piRNA clusters are evolutionarily labile and dispensable for transposon regulation. Mol Cell 2021; 81:3965-3978.e5. [PMID: 34352205 PMCID: PMC8516431 DOI: 10.1016/j.molcel.2021.07.011] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Revised: 05/23/2021] [Accepted: 07/10/2021] [Indexed: 12/13/2022]
Abstract
PIWI proteins and their guiding Piwi-interacting small RNAs (piRNAs) are crucial for fertility and transposon defense in the animal germline. In most species, the majority of piRNAs are produced from distinct large genomic loci, called piRNA clusters. It is assumed that germline-expressed piRNA clusters, particularly in Drosophila, act as principal regulators to control transposons dispersed across the genome. Here, using synteny analysis, we show that large clusters are evolutionarily labile, arise at loci characterized by recurrent chromosomal rearrangements, and are mostly species-specific across the Drosophila genus. By engineering chromosomal deletions in D. melanogaster, we demonstrate that the three largest germline clusters, which account for the accumulation of >40% of all transposon-targeting piRNAs in ovaries, are neither required for fertility nor for transposon regulation in trans. We provide further evidence that dispersed elements, rather than the regulatory action of large Drosophila germline clusters in trans, may be central for transposon defense.
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Affiliation(s)
- Daniel Gebert
- Department of Genetics, University of Cambridge, Cambridge CB2 3EH, UK
| | - Lena K Neubert
- Department of Genetics, University of Cambridge, Cambridge CB2 3EH, UK
| | - Catrin Lloyd
- Department of Genetics, University of Cambridge, Cambridge CB2 3EH, UK
| | - Jinghua Gui
- Department of Genetics, University of Cambridge, Cambridge CB2 3EH, UK
| | - Ruth Lehmann
- Howard Hughes Medical Institute (HHMI) and Kimmel Center for Biology and Medicine of the Skirball Institute, Department of Cell Biology, New York University School of Medicine, New York, NY 10016, USA.
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18
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Gibert JM, Peronnet F. The Paramount Role of Drosophila melanogaster in the Study of Epigenetics: From Simple Phenotypes to Molecular Dissection and Higher-Order Genome Organization. Insects 2021; 12:884. [PMID: 34680653 DOI: 10.3390/insects12100884] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Revised: 09/24/2021] [Accepted: 09/26/2021] [Indexed: 01/06/2023]
Abstract
Simple Summary Since its adoption as a model organism more than a hundred years ago, the fruit fly Drosophila melanogaster has led to major discoveries in biology, notably in epigenetics. Epigenetics studies the changes in gene function inherited through mitosis or meiosis that are not due to modifications in the DNA sequence. The first discoveries in epigenetics emerged from analyses of the perturbations of simple phenotypes such as the bristle position or cuticle pigmentation. Identification of the mutated genes led to the discovery of major chromatin regulators, which were found to be conserved in other insects, and unexpectedly, in all metazoans. Many of them deposit post-translational modifications on histones, the proteins around which the DNA is wrapped. Others are chromatin remodeling complexes that move, eject, or exchange nucleosomes. We review here the role of D. melanogaster research in three important epigenetic fields: The formation of heterochromatin, the repression of mobile DNA elements by small RNAs, and the regulation of gene expression by the antagonistic Polycomb and Trithorax complexes. We then review how genetic tools available in D. melanogaster have allowed us to examine the role of histone marks and led to more global discoveries on chromatin organization. Lastly, we discuss the impact of varying environmental conditions on epigenetic regulation. Abstract Drosophila melanogaster has played a paramount role in epigenetics, the study of changes in gene function inherited through mitosis or meiosis that are not due to changes in the DNA sequence. By analyzing simple phenotypes, such as the bristle position or cuticle pigmentation, as read-outs of regulatory processes, the identification of mutated genes led to the discovery of major chromatin regulators. These are often conserved in distantly related organisms such as vertebrates or even plants. Many of them deposit, recognize, or erase post-translational modifications on histones (histone marks). Others are members of chromatin remodeling complexes that move, eject, or exchange nucleosomes. We review the role of D. melanogaster research in three epigenetic fields: Heterochromatin formation and maintenance, the repression of transposable elements by piRNAs, and the regulation of gene expression by the antagonistic Polycomb and Trithorax complexes. We then describe how genetic tools available in D. melanogaster allowed to examine the role of histone marks and show that some histone marks are dispensable for gene regulation, whereas others play essential roles. Next, we describe how D. melanogaster has been particularly important in defining chromatin types, higher-order chromatin structures, and their dynamic changes during development. Lastly, we discuss the role of epigenetics in a changing environment.
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19
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Crava CM, Varghese FS, Pischedda E, Halbach R, Palatini U, Marconcini M, Gasmi L, Redmond S, Afrane Y, Ayala D, Paupy C, Carballar‐Lejarazu R, Miesen P, van Rij RP, Bonizzoni M. Population genomics in the arboviral vector Aedes aegypti reveals the genomic architecture and evolution of endogenous viral elements. Mol Ecol 2021; 30:1594-1611. [PMID: 33432714 PMCID: PMC8048955 DOI: 10.1111/mec.15798] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 01/05/2021] [Accepted: 01/07/2021] [Indexed: 02/06/2023]
Abstract
Horizontal gene transfer from viruses to eukaryotic cells is a pervasive phenomenon. Somatic viral integrations are linked to persistent viral infection whereas integrations into germline cells are maintained in host genomes by vertical transmission and may be co-opted for host functions. In the arboviral vector Aedes aegypti, an endogenous viral element from a nonretroviral RNA virus (nrEVE) was shown to produce PIWI-interacting RNAs (piRNAs) to limit infection with a cognate virus. Thus, nrEVEs may constitute a heritable, sequence-specific mechanism for antiviral immunity, analogous to piRNA-mediated silencing of transposable elements. Here, we combine population genomics and evolutionary approaches to analyse the genomic architecture of nrEVEs in A. aegypti. We conducted a genome-wide screen for adaptive nrEVEs and searched for novel population-specific nrEVEs in the genomes of 80 individual wild-caught mosquitoes from five geographical populations. We show a dynamic landscape of nrEVEs in mosquito genomes and identified five novel nrEVEs derived from two currently circulating viruses, providing evidence of the environmental-dependent modification of a piRNA cluster. Overall, our results show that virus endogenization events are complex with only a few nrEVEs contributing to adaptive evolution in A. aegypti.
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Affiliation(s)
- Cristina M. Crava
- Department of Biology and BiotechnologyUniversity of PaviaPaviaItaly
- Present address:
Institute of Biotechnology and BiomedicineUniversitat de ValènciaBurjassotSpain
| | - Finny S. Varghese
- Department of Medical MicrobiologyRadboud University Medical CenterRadboud Institute for Molecular Life SciencesNijmegenThe Netherlands
| | - Elisa Pischedda
- Department of Biology and BiotechnologyUniversity of PaviaPaviaItaly
| | - Rebecca Halbach
- Department of Medical MicrobiologyRadboud University Medical CenterRadboud Institute for Molecular Life SciencesNijmegenThe Netherlands
| | - Umberto Palatini
- Department of Biology and BiotechnologyUniversity of PaviaPaviaItaly
| | | | - Leila Gasmi
- Department of Biology and BiotechnologyUniversity of PaviaPaviaItaly
| | - Seth Redmond
- Institute of Vector Borne DiseaseMonash UniversityAustralia
| | - Yaw Afrane
- Department of Medical MicrobiologyUniversity of GhanaAccraGhana
| | - Diego Ayala
- MIVEGECUniv. MontpellierIRDCNRSMontpellierFrance
| | | | - Rebeca Carballar‐Lejarazu
- Department of Biology and BiotechnologyUniversity of PaviaPaviaItaly
- Present address:
Department of Molecular Biology and BiochemistryUniversity of California at IrvineIrvineCAUSA
| | - Pascal Miesen
- Department of Medical MicrobiologyRadboud University Medical CenterRadboud Institute for Molecular Life SciencesNijmegenThe Netherlands
| | - Ronald P. van Rij
- Department of Medical MicrobiologyRadboud University Medical CenterRadboud Institute for Molecular Life SciencesNijmegenThe Netherlands
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20
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Weilguny L, Vlachos C, Selvaraju D, Kofler R. Reconstructing the Invasion Route of the P-Element in Drosophila melanogaster Using Extant Population Samples. Genome Biol Evol 2020; 12:2139-2152. [PMID: 33210145 PMCID: PMC7750958 DOI: 10.1093/gbe/evaa190] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/06/2020] [Indexed: 12/19/2022] Open
Abstract
The P-element, one of the best understood eukaryotic transposable elements, spread in natural Drosophila melanogaster populations in the last century. It invaded American populations first and later spread to the Old World. Inferring this invasion route was made possible by a unique resource available in D. melanogaster: Many strains sampled from different locations over the course of the last century. Here, we test the hypothesis that the invasion route of the P-element may be reconstructed from extant population samples using internal deletions (IDs) as markers. These IDs arise at a high rate when DNA transposons, such as the P-element, are active. We suggest that inferring invasion routes is possible as: 1) the fraction of IDs increases in successively invaded populations, which also explains the striking differences in the ID content between American and European populations, and 2) successively invaded populations end up with similar sets of IDs. This approach allowed us to reconstruct the invasion route of the P-element with reasonable accuracy. Our approach also sheds light on the unknown timing of the invasion in African populations: We suggest that African populations were invaded after American but before European populations. Simulations of TE invasions in spatially distributed populations confirm that IDs may allow us to infer invasion routes. Our approach might be applicable to other DNA transposons in different host species.
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Affiliation(s)
- Lukas Weilguny
- Institut für Populationsgenetik, Vetmeduni Vienna, Wien, Austria
| | - Christos Vlachos
- Institut für Populationsgenetik, Vetmeduni Vienna, Wien, Austria.,Vienna Graduate School of Population Genetics, Wien, Austria
| | - Divya Selvaraju
- Institut für Populationsgenetik, Vetmeduni Vienna, Wien, Austria.,Vienna Graduate School of Population Genetics, Wien, Austria
| | - Robert Kofler
- Institut für Populationsgenetik, Vetmeduni Vienna, Wien, Austria
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21
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Gamez S, Srivastav S, Akbari OS, Lau NC. Diverse Defenses: A Perspective Comparing Dipteran Piwi-piRNA Pathways. Cells 2020; 9:E2180. [PMID: 32992598 PMCID: PMC7601171 DOI: 10.3390/cells9102180] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Revised: 09/22/2020] [Accepted: 09/23/2020] [Indexed: 02/07/2023] Open
Abstract
Animals face the dual threat of virus infections hijacking cellular function and transposons proliferating in germline genomes. For insects, the deeply conserved RNA interference (RNAi) pathways and other chromatin regulators provide an important line of defense against both viruses and transposons. For example, this innate immune system displays adaptiveness to new invasions by generating cognate small RNAs for targeting gene silencing measures against the viral and genomic intruders. However, within the Dipteran clade of insects, Drosophilid fruit flies and Culicids mosquitoes have evolved several unique mechanistic aspects of their RNAi defenses to combat invading transposons and viruses, with the Piwi-piRNA arm of the RNAi pathways showing the greatest degree of novel evolution. Whereas central features of Piwi-piRNA pathways are conserved between Drosophilids and Culicids, multiple lineage-specific innovations have arisen that may reflect distinct genome composition differences and specific ecological and physiological features dividing these two branches of Dipterans. This perspective review focuses on the most recent findings illuminating the Piwi/piRNA pathway distinctions between fruit flies and mosquitoes, and raises open questions that need to be addressed in order to ameliorate human diseases caused by pathogenic viruses that mosquitoes transmit as vectors.
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Affiliation(s)
- Stephanie Gamez
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California, San Diego, CA 92093, USA; (S.G.); (O.S.A.)
| | - Satyam Srivastav
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853-2703, USA;
| | - Omar S. Akbari
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California, San Diego, CA 92093, USA; (S.G.); (O.S.A.)
| | - Nelson C. Lau
- Department of Biochemistry and Genome Science Institute, Boston University School of Medicine, Boston, MA 02118, USA
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22
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Kim IV, Riedelbauch S, Kuhn CD. The piRNA pathway in planarian flatworms: new model, new insights. Biol Chem 2020; 401:1123-1141. [DOI: 10.1515/hsz-2019-0445] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Accepted: 03/12/2020] [Indexed: 12/22/2022]
Abstract
AbstractPIWI-interacting RNAs (piRNAs) are small regulatory RNAs that associate with members of the PIWI clade of the Argonaute superfamily of proteins. piRNAs are predominantly found in animal gonads. There they silence transposable elements (TEs), regulate gene expression and participate in DNA methylation, thus orchestrating proper germline development. Furthermore, PIWI proteins are also indispensable for the maintenance and differentiation capabilities of pluripotent stem cells in free-living invertebrate species with regenerative potential. Thus, PIWI proteins and piRNAs seem to constitute an essential molecular feature of somatic pluripotent stem cells and the germline. In keeping with this hypothesis, both PIWI proteins and piRNAs are enriched in neoblasts, the adult stem cells of planarian flatworms, and their presence is a prerequisite for the proper regeneration and perpetual tissue homeostasis of these animals. The piRNA pathway is required to maintain the unique biology of planarians because, in analogy to the animal germline, planarian piRNAs silence TEs and ensure stable genome inheritance. Moreover, planarian piRNAs also contribute to the degradation of numerous protein-coding transcripts, a function that may be critical for neoblast differentiation. This review gives an overview of the planarian piRNA pathway and of its crucial function in neoblast biology.
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Affiliation(s)
- Iana V. Kim
- Gene regulation by Non-coding RNA, Elite Network of Bavaria and University of Bayreuth, Universitätsstrasse 30, D-95447 Bayreuth, Germany
| | - Sebastian Riedelbauch
- Gene regulation by Non-coding RNA, Elite Network of Bavaria and University of Bayreuth, Universitätsstrasse 30, D-95447 Bayreuth, Germany
| | - Claus-D. Kuhn
- Gene regulation by Non-coding RNA, Elite Network of Bavaria and University of Bayreuth, Universitätsstrasse 30, D-95447 Bayreuth, Germany
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23
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24
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Kakan SS, Janga SR, Cooperman B, Craig DW, Edman MC, Okamoto CT, Hamm-Alvarez SF. Small RNA Deep Sequencing Identifies a Unique miRNA Signature Released in Serum Exosomes in a Mouse Model of Sjögren's Syndrome. Front Immunol 2020; 11:1475. [PMID: 32849505 PMCID: PMC7396589 DOI: 10.3389/fimmu.2020.01475] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Accepted: 06/05/2020] [Indexed: 12/18/2022] Open
Abstract
Sjögren's Syndrome (SS) is an autoimmune disease characterized by lymphocytic infiltration and loss of function of moisture-producing exocrine glands as well as systemic inflammation. SS diagnosis is cumbersome, subjective and complicated by manifestation of symptoms that overlap with those of other rheumatic and ocular diseases. Definitive diagnosis averages 4–5 years and this delay may lead to irreversible tissue damage. Thus, there is an urgent need for diagnostic biomarkers for earlier detection of SS. Extracellular vesicles called exosomes carry functional small non-coding RNAs which play a critical role in maintaining cellular homeostasis via transcriptional and translational regulation of mRNA. Alterations in levels of specific exosomal miRNAs may be predictive of disease status. Here, we have assessed serum exosomal RNA using next generation sequencing in a discovery cohort of the NOD mouse, a model of early-intermediate SS, to identify dysregulated miRNAs that may be indicative of SS. We found five miRNAs upregulated in serum exosomes of NOD mice with an adjusted p < 0.05—miRNA-127-3p, miRNA-409-3p, miRNA-410-3p, miRNA-541-5p, and miRNA-540-5p. miRNAs 127-3p and 541-5p were also statistically significantly upregulated in a validation cohort of NOD mice. Pathway analysis and existing literature indicates that differential expression of these miRNAs may dysregulate pathways involved in inflammation. Future studies will apply these findings in a human cohort to understand how they are correlated with manifestations of SS as well as understanding their functional role in systemic autoimmunity specific to SS.
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Affiliation(s)
- Shruti Singh Kakan
- Department of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles, CA, United States
| | - Srikanth R Janga
- Department of Ophthalmology, Keck School of Medicine, Roski Eye Institute, University of Southern California, Los Angeles, CA, United States
| | - Benjamin Cooperman
- Department of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles, CA, United States
| | - David W Craig
- Department of Translational Genomics, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States
| | - Maria C Edman
- Department of Ophthalmology, Keck School of Medicine, Roski Eye Institute, University of Southern California, Los Angeles, CA, United States
| | - Curtis T Okamoto
- Department of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles, CA, United States
| | - Sarah F Hamm-Alvarez
- Department of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles, CA, United States.,Department of Ophthalmology, Keck School of Medicine, Roski Eye Institute, University of Southern California, Los Angeles, CA, United States
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25
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Liu X, Kosugi S, Koide R, Kawamura Y, Ito J, Miura H, Matoba N, Matsuzaki M, Fujita M, Kamada AJ, Nakagawa H, Tamiya G, Matsuda K, Murakami Y, Kubo M, Aswad A, Sato K, Momozawa Y, Ohashi J, Terao C, Yoshikawa T, Parrish NF, Kamatani Y. Endogenization and excision of human herpesvirus 6 in human genomes. PLoS Genet 2020; 16:e1008915. [PMID: 32776928 PMCID: PMC7444522 DOI: 10.1371/journal.pgen.1008915] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Revised: 08/20/2020] [Accepted: 06/07/2020] [Indexed: 12/12/2022] Open
Abstract
Sequences homologous to human herpesvirus 6 (HHV-6) are integrated within the nuclear genome of about 1% of humans, but it is not clear how this came about. It is also uncertain whether integrated HHV-6 can reactivate into an infectious virus. HHV-6 integrates into telomeres, and this has recently been associated with polymorphisms affecting MOV10L1. MOV10L1 is located on the subtelomere of chromosome 22q (chr22q) and is required to make PIWI-interacting RNAs (piRNAs). As piRNAs block germline integration of transposons, piRNA-mediated repression of HHV-6 integration has been proposed to explain this association. In vitro, recombination of the HHV-6 genome along its terminal direct repeats (DRs) leads to excision from the telomere and viral reactivation, but the expected "solo-DR scar" has not been described in vivo. Here we screened for integrated HHV-6 in 7,485 Japanese subjects using whole-genome sequencing (WGS). Integrated HHV-6 was associated with polymorphisms on chr22q. However, in contrast to prior work, we find that the reported MOV10L1 polymorphism is physically linked to an ancient endogenous HHV-6A variant integrated into the telomere of chr22q in East Asians. Unexpectedly, an HHV-6B variant has also endogenized in chr22q; two endogenous HHV-6 variants at this locus thus account for 72% of all integrated HHV-6 in Japan. We also report human genomes carrying only one portion of the HHV-6B genome, a solo-DR, supporting in vivo excision and possible viral reactivation. Together these results explain the recently-reported association between integrated HHV-6 and MOV10L1/piRNAs, suggest potential exaptation of HHV-6 in its coevolution with human chr22q, and clarify the evolution and risk of reactivation of the only intact (non-retro)viral genome known to be present in human germlines.
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Affiliation(s)
- Xiaoxi Liu
- Genome Immunobiology RIKEN Hakubi Research Team, RIKEN Cluster for Pioneering Research and RIKEN Center for Integrative Medical Sciences, Yokohama, Japan
| | - Shunichi Kosugi
- Laboratory for Statistical and Translational Genetics, RIKEN Center for Integrative Medical Sciences, Yokohama, Japan
| | - Rie Koide
- Genome Immunobiology RIKEN Hakubi Research Team, RIKEN Cluster for Pioneering Research and RIKEN Center for Integrative Medical Sciences, Yokohama, Japan
| | - Yoshiki Kawamura
- Department of Pediatrics, Fujita Health University School of Medicine, Toyoake, Japan
| | - Jumpei Ito
- Division of Systems Virology, Department of Infectious Disease Control, International Research Center for Infectious Diseases, Institute of Medical Science, The University of Tokyo, Tokyo, Japan
| | - Hiroki Miura
- Department of Pediatrics, Fujita Health University School of Medicine, Toyoake, Japan
| | - Nana Matoba
- Laboratory for Statistical and Translational Genetics, RIKEN Center for Integrative Medical Sciences, Yokohama, Japan
| | - Motomichi Matsuzaki
- Statistical Genetics Team, RIKEN Center for Advanced Intelligence Project, Tokyo, Japan
| | - Masashi Fujita
- Laboratory for Cancer Genomics, RIKEN Center for Integrative Medical Sciences, Yokohama, Japan
| | - Anselmo Jiro Kamada
- Genome Immunobiology RIKEN Hakubi Research Team, RIKEN Cluster for Pioneering Research and RIKEN Center for Integrative Medical Sciences, Yokohama, Japan
| | - Hidewaki Nakagawa
- Laboratory for Cancer Genomics, RIKEN Center for Integrative Medical Sciences, Yokohama, Japan
| | - Gen Tamiya
- Statistical Genetics Team, RIKEN Center for Advanced Intelligence Project, Tokyo, Japan
| | - Koichi Matsuda
- Laboratory of Molecular Medicine, Institute of Medical Science, The University of Tokyo, Tokyo, Japan
- Laboratory for Clinical Genome Sequencing, Graduate School of Frontier Sciences, The University of Tokyo, Tokyo, Japan
| | - Yoshinori Murakami
- Division of Molecular Pathology, Institute of Medical Science, The University of Tokyo, Tokyo, Japan
| | - Michiaki Kubo
- RIKEN Center for Integrative Medical Sciences, Yokohama, Japan
| | - Amr Aswad
- Institut für Virologie, Freie Universität Berlin, Berlin, Germany
| | - Kei Sato
- Division of Systems Virology, Department of Infectious Disease Control, International Research Center for Infectious Diseases, Institute of Medical Science, The University of Tokyo, Tokyo, Japan
| | - Yukihide Momozawa
- Laboratory for Genotyping Development, RIKEN Center for Integrative Medical Sciences, Yokohama, Japan
| | - Jun Ohashi
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo, Japan
| | - Chikashi Terao
- Laboratory for Statistical and Translational Genetics, RIKEN Center for Integrative Medical Sciences, Yokohama, Japan
| | - Tetsushi Yoshikawa
- Department of Pediatrics, Fujita Health University School of Medicine, Toyoake, Japan
| | - Nicholas F. Parrish
- Genome Immunobiology RIKEN Hakubi Research Team, RIKEN Cluster for Pioneering Research and RIKEN Center for Integrative Medical Sciences, Yokohama, Japan
- * E-mail:
| | - Yoichiro Kamatani
- Laboratory for Statistical and Translational Genetics, RIKEN Center for Integrative Medical Sciences, Yokohama, Japan
- Laboratory of Complex Trait Genomics, Graduate School of Frontier Sciences, The University of Tokyo, Japan
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26
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Mohamed M, Dang NTM, Ogyama Y, Burlet N, Mugat B, Boulesteix M, Mérel V, Veber P, Salces-Ortiz J, Severac D, Pélisson A, Vieira C, Sabot F, Fablet M, Chambeyron S. A Transposon Story: From TE Content to TE Dynamic Invasion of Drosophila Genomes Using the Single-Molecule Sequencing Technology from Oxford Nanopore. Cells 2020; 9:E1776. [PMID: 32722451 PMCID: PMC7465170 DOI: 10.3390/cells9081776] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2020] [Revised: 07/17/2020] [Accepted: 07/23/2020] [Indexed: 11/17/2022] Open
Abstract
Transposable elements (TEs) are the main components of genomes. However, due to their repetitive nature, they are very difficult to study using data obtained with short-read sequencing technologies. Here, we describe an efficient pipeline to accurately recover TE insertion (TEI) sites and sequences from long reads obtained by Oxford Nanopore Technology (ONT) sequencing. With this pipeline, we could precisely describe the landscapes of the most recent TEIs in wild-type strains of Drosophila melanogaster and Drosophila simulans. Their comparison suggests that this subset of TE sequences is more similar than previously thought in these two species. The chromosome assemblies obtained using this pipeline also allowed recovering piRNA cluster sequences, which was impossible using short-read sequencing. Finally, we used our pipeline to analyze ONT sequencing data from a D. melanogaster unstable line in which LTR transposition was derepressed for 73 successive generations. We could rely on single reads to identify new insertions with intact target site duplications. Moreover, the detailed analysis of TEIs in the wild-type strains and the unstable line did not support the trap model claiming that piRNA clusters are hotspots of TE insertions.
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Affiliation(s)
- Mourdas Mohamed
- Institute of Human Genetics, UMR9002, CNRS and Montpellier University, 34396 Montpellier, France; (M.M.); (Y.O.); (B.M.); (A.P.)
| | - Nguyet Thi-Minh Dang
- IRD/UM UMR DIADE, 911 avenue Agropolis BP64501, 34394 Montpellier, France; (N.T.-M.D.); (F.S.)
| | - Yuki Ogyama
- Institute of Human Genetics, UMR9002, CNRS and Montpellier University, 34396 Montpellier, France; (M.M.); (Y.O.); (B.M.); (A.P.)
| | - Nelly Burlet
- Université de Lyon, Université Lyon 1, CNRS, Laboratoire de Biométrie et Biologie Evolutive UMR 5558, 69622 Villeurbanne, France; (N.B.); (M.B.); (V.M.); (P.V.); (J.S.-O.); (C.V.)
| | - Bruno Mugat
- Institute of Human Genetics, UMR9002, CNRS and Montpellier University, 34396 Montpellier, France; (M.M.); (Y.O.); (B.M.); (A.P.)
| | - Matthieu Boulesteix
- Université de Lyon, Université Lyon 1, CNRS, Laboratoire de Biométrie et Biologie Evolutive UMR 5558, 69622 Villeurbanne, France; (N.B.); (M.B.); (V.M.); (P.V.); (J.S.-O.); (C.V.)
| | - Vincent Mérel
- Université de Lyon, Université Lyon 1, CNRS, Laboratoire de Biométrie et Biologie Evolutive UMR 5558, 69622 Villeurbanne, France; (N.B.); (M.B.); (V.M.); (P.V.); (J.S.-O.); (C.V.)
| | - Philippe Veber
- Université de Lyon, Université Lyon 1, CNRS, Laboratoire de Biométrie et Biologie Evolutive UMR 5558, 69622 Villeurbanne, France; (N.B.); (M.B.); (V.M.); (P.V.); (J.S.-O.); (C.V.)
| | - Judit Salces-Ortiz
- Université de Lyon, Université Lyon 1, CNRS, Laboratoire de Biométrie et Biologie Evolutive UMR 5558, 69622 Villeurbanne, France; (N.B.); (M.B.); (V.M.); (P.V.); (J.S.-O.); (C.V.)
- Institute of Evolutionary Biology (IBE), CSIC-Universitat Pompeu Fabra, 08003 Barcelona, Spain
| | - Dany Severac
- MGX-Montpellier GenomiX, c/o Institut de Génomique Fonctionnelle, CNRS, INSERM, Université de Montpellier, 34094 Montpellier, France;
| | - Alain Pélisson
- Institute of Human Genetics, UMR9002, CNRS and Montpellier University, 34396 Montpellier, France; (M.M.); (Y.O.); (B.M.); (A.P.)
| | - Cristina Vieira
- Université de Lyon, Université Lyon 1, CNRS, Laboratoire de Biométrie et Biologie Evolutive UMR 5558, 69622 Villeurbanne, France; (N.B.); (M.B.); (V.M.); (P.V.); (J.S.-O.); (C.V.)
| | - François Sabot
- IRD/UM UMR DIADE, 911 avenue Agropolis BP64501, 34394 Montpellier, France; (N.T.-M.D.); (F.S.)
| | - Marie Fablet
- Université de Lyon, Université Lyon 1, CNRS, Laboratoire de Biométrie et Biologie Evolutive UMR 5558, 69622 Villeurbanne, France; (N.B.); (M.B.); (V.M.); (P.V.); (J.S.-O.); (C.V.)
| | - Séverine Chambeyron
- Institute of Human Genetics, UMR9002, CNRS and Montpellier University, 34396 Montpellier, France; (M.M.); (Y.O.); (B.M.); (A.P.)
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27
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Mentis AFA, Dardiotis E, Romas NA, Papavassiliou AG. PIWI family proteins as prognostic markers in cancer: a systematic review and meta-analysis. Cell Mol Life Sci 2020; 77:2289-2314. [PMID: 31814070 PMCID: PMC11104808 DOI: 10.1007/s00018-019-03403-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Revised: 11/26/2019] [Accepted: 11/28/2019] [Indexed: 02/07/2023]
Abstract
BACKGROUND P-element-induced-wimpy-testis-(PIWI)-like proteins are implicated in germ cells' regulation and detected in numerous cancer types. In this meta-analysis, we aimed to associate, for the first time, the prognosis in cancer patients with intratumoral expression of PIWI family proteins. METHODS PubMed, Embase, and Web of Knowledge databases were searched, and studies investigating the association between intratumoral mRNA or protein expression of different PIWI family proteins and survival, metastasis, or recurrence of various cancer types were reviewed. Study qualities were assessed using the REMARK criteria. Studies' heterogeneity was evaluated using I2 index and Cochran Q test. Publication bias was assessed by funnel plots and Egger's regression. Pooled hazard ratios (HR) with 95% confidence intervals (95% CIs) were calculated for different PIWI family proteins separately. Specifically, log of calculated HR was pooled using random-effects model. RESULTS Twenty-six studies (4299 participants) were included. The pooled HR of mortality in high versus low expression of PIWIL1, PIWIL2, and PIWIL4 was 1.87 (95% CI: 1.31-2.66, p < 0.05), 1.09 (95% CI: 0.58-2.07, p = 0.79), and 0.44 (95% CI: 0.25-0.76, p < 0.05), respectively. The pooled HR of recurrence in high versus low expression of PIWIL1 and PIWIL2 was 1.72 (95% CI: 1.20-2.49, p < 0.05) and 1.98 (95% CI: 0.65-5.98, p = 0.23), respectively. CONCLUSIONS Highly variable results were observed for different cancer types. Higher PIWIL1 and lower piwil4 and PIWIL4 expression levels could potentially indicate worse prognosis in cancer. These proteins' expressions could be used for personalized prognosis and treatment in the future.
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Affiliation(s)
- Alexios-Fotios A Mentis
- Public Health Laboratories, Hellenic Pasteur Institute, Athens, Greece
- Department of Microbiology, University Hospital of Thessaly, Larissa, Greece
| | | | - Nicholas A Romas
- Department of Urology, Columbia University Medical Center, Vagelos College of Physicians and Surgeons, New York, USA
| | - Athanasios G Papavassiliou
- Department of Biological Chemistry, Medical School, National and Kapodistrian University of Athens, 75 M. Asias Street - Bldg. 16, 11527, Athens, Greece.
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28
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Abstract
piRNA clusters are thought to repress transposable element (TE) activity in mammals and invertebrates. Here, we show that a simple population genetics model reveals a constraint on the size of piRNA clusters: The total size of the piRNA clusters of an organism must exceed 0.2% of a genome to repress TE invasions. Moreover, larger piRNA clusters accounting for up to 3% of the genome may be necessary when populations are small, transposition rates are high, and TE insertions are recessive. If piRNA clusters are too small, the load of deleterious TE insertions that accumulate during a TE invasion may drive populations extinct before an effective piRNA-based defense against the TE can be established. Our findings are solely based on three well-supported assumptions: 1) TEs multiply within genomes, 2) TEs are mostly deleterious, and 3) piRNA clusters act as transposon traps, where a single insertion in a cluster silences all TE copies in trans. Interestingly, the piRNA clusters of some species meet our observed minimum size requirements, whereas the clusters of other species do not. Species with small piRNA clusters, such as humans and mice, may experience severe fitness reductions during invasions of novel TEs, which is possibly even threatening the persistence of some populations. This work also raises the important question of how piRNA clusters evolve. We propose that the size of piRNA clusters may be at an equilibrium between evolutionary forces that act to expand and contract piRNA clusters.
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Affiliation(s)
- Robert Kofler
- Institut für Populationsgenetik, Vetmeduni Vienna, Wien, Austria
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29
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Kukushkina IV, Makhnovskii PA, Nefedova LN, Balakireva EA, Romanova NI, Kuzmin IV, Lavrenov AR, Kim AI. A Study of the Fertility of a Drosophila melanogaster MS Strain with Impaired Transposition Control of the gypsy Mobile Element. Mol Biol 2020. [DOI: 10.1134/s0026893320030097] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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30
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Ophinni Y, Palatini U, Hayashi Y, Parrish NF. piRNA-Guided CRISPR-like Immunity in Eukaryotes. Trends Immunol 2019; 40:998-1010. [DOI: 10.1016/j.it.2019.09.003] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2019] [Revised: 09/17/2019] [Accepted: 09/17/2019] [Indexed: 02/07/2023]
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