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Blumenstiel JP. From the cauldron of conflict: Endogenous gene regulation by piRNA and other modes of adaptation enabled by selfish transposable elements. Semin Cell Dev Biol 2024; 164:1-12. [PMID: 38823219 DOI: 10.1016/j.semcdb.2024.05.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Revised: 04/28/2024] [Accepted: 05/06/2024] [Indexed: 06/03/2024]
Abstract
Transposable elements (TEs) provide a prime example of genetic conflict because they can proliferate in genomes and populations even if they harm the host. However, numerous studies have shown that TEs, though typically harmful, can also provide fuel for adaptation. This is because they code functional sequences that can be useful for the host in which they reside. In this review, I summarize the "how" and "why" of adaptation enabled by the genetic conflict between TEs and hosts. In addition, focusing on mechanisms of TE control by small piwi-interacting RNAs (piRNAs), I highlight an indirect form of adaptation enabled by conflict. In this case, mechanisms of host defense that regulate TEs have been redeployed for endogenous gene regulation. I propose that the genetic conflict released by meiosis in early eukaryotes may have been important because, among other reasons, it spurred evolutionary innovation on multiple interwoven trajectories - on the part of hosts and also embedded genetic parasites. This form of evolution may function as a complexity generating engine that was a critical player in eukaryotic evolution.
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Affiliation(s)
- Justin P Blumenstiel
- Department of Ecology and Evolutionary Biology, University of Kansas, 1200 Sunnyside Avenue, Lawrence, KS 66045, United States.
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2
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Hubley R, Wheeler TJ, Smit AFA. Accuracy of multiple sequence alignment methods in the reconstruction of transposable element families. NAR Genom Bioinform 2022; 4:lqac040. [PMID: 35591887 PMCID: PMC9112768 DOI: 10.1093/nargab/lqac040] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Revised: 03/29/2022] [Accepted: 04/29/2022] [Indexed: 02/06/2023] Open
Abstract
The construction of a high-quality multiple sequence alignment (MSA) from copies of a transposable element (TE) is a critical step in the characterization of a new TE family. Most studies of MSA accuracy have been conducted on protein or RNA sequence families, where structural features and strong signals of selection may assist with alignment. Less attention has been given to the quality of sequence alignments involving neutrally evolving DNA sequences such as those resulting from TE replication. Transposable element sequences are challenging to align due to their wide divergence ranges, fragmentation, and predominantly-neutral mutation patterns. To gain insight into the effects of these properties on MSA accuracy, we developed a simulator of TE sequence evolution, and used it to generate a benchmark with which we evaluated the MSA predictions produced by several popular aligners, along with Refiner, a method we developed in the context of our RepeatModeler software. We find that MAFFT and Refiner generally outperform other aligners for low to medium divergence simulated sequences, while Refiner is uniquely effective when tasked with aligning high-divergent and fragmented instances of a family.
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Affiliation(s)
- Robert Hubley
- Institute for Systems Biology, Seattle, WA 98109, USA
| | - Travis J Wheeler
- Department of Computer Science, University of Montana, Missoula, MT 59801, USA
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3
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Lié O, Renault S, Augé-Gouillou C. SETMAR, a case of primate co-opted genes: towards new perspectives. Mob DNA 2022; 13:9. [PMID: 35395947 PMCID: PMC8994322 DOI: 10.1186/s13100-022-00267-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2021] [Accepted: 03/28/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND We carry out a review of the history and biological activities of one domesticated gene in higher primates, SETMAR, by discussing current controversies. Our purpose is to open a new outlook that will serve as a framework for future work about SETMAR, possibly in the field of cognition development. MAIN BODY What is newly important about SETMAR can be summarized as follows: (1) the whole protein sequence is under strong purifying pressure; (2) its role is to strengthen existing biological functions rather than to provide new ones; (3) it displays a tissue-specific pattern of expression, at least for the alternative-splicing it undergoes. Studies reported here demonstrate that SETMAR protein(s) may be involved in essential networks regulating replication, transcription and translation. Moreover, during embryogenesis, SETMAR appears to contribute to brain development. SHORT CONCLUSION Our review underlines for the first time that SETMAR directly interacts with genes involved in brain functions related to vocalization and vocal learning. These findings pave the way for future works regarding SETMAR and the development of cognitive abilities in higher primates.
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Affiliation(s)
- Oriane Lié
- UMR 1253, iBrain, Université de Tours, Inserm, Tours, France.,iBrain, Team Neurogenomics and Neuronal physiopathology, Faculty of Medicine, 10 Bd Tonnellé, Cedex 1, 37032, Tours, France
| | - Sylvaine Renault
- UMR 1253, iBrain, Université de Tours, Inserm, Tours, France.,iBrain, Team Neurogenomics and Neuronal physiopathology, Faculty of Medicine, 10 Bd Tonnellé, Cedex 1, 37032, Tours, France
| | - Corinne Augé-Gouillou
- UMR 1253, iBrain, Université de Tours, Inserm, Tours, France. .,iBrain, Team Neurogenomics and Neuronal physiopathology, Faculty of Medicine, 10 Bd Tonnellé, Cedex 1, 37032, Tours, France.
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4
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Structural and genome-wide analyses suggest that transposon-derived protein SETMAR alters transcription and splicing. J Biol Chem 2022; 298:101894. [PMID: 35378129 PMCID: PMC9062482 DOI: 10.1016/j.jbc.2022.101894] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2021] [Revised: 03/25/2022] [Accepted: 03/26/2022] [Indexed: 11/22/2022] Open
Abstract
Extensive portions of the human genome have unknown function, including those derived from transposable elements. One such element, the DNA transposon Hsmar1, entered the primate lineage approximately 50 million years ago leaving behind terminal inverted repeat (TIR) sequences and a single intact copy of the Hsmar1 transposase, which retains its ancestral TIR-DNA-binding activity, and is fused with a lysine methyltransferase SET domain to constitute the chimeric SETMAR gene. Here, we provide a structural basis for recognition of TIRs by SETMAR and investigate the function of SETMAR through genome-wide approaches. As elucidated in our 2.37 Å crystal structure, SETMAR forms a dimeric complex with each DNA-binding domain bound specifically to TIR-DNA through the formation of 32 hydrogen bonds. We found that SETMAR recognizes primarily TIR sequences (∼5000 sites) within the human genome as assessed by chromatin immunoprecipitation sequencing analysis. In two SETMAR KO cell lines, we identified 163 shared differentially expressed genes and 233 shared alternative splicing events. Among these genes are several pre–mRNA-splicing factors, transcription factors, and genes associated with neuronal function, and one alternatively spliced primate-specific gene, TMEM14B, which has been identified as a marker for neocortex expansion associated with brain evolution. Taken together, our results suggest a model in which SETMAR impacts differential expression and alternative splicing of genes associated with transcription and neuronal function, potentially through both its TIR-specific DNA-binding and lysine methyltransferase activities, consistent with a role for SETMAR in simian primate development.
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5
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Nickoloff JA, Sharma N, Taylor L, Allen SJ, Lee SH, Hromas R. Metnase and EEPD1: DNA Repair Functions and Potential Targets in Cancer Therapy. Front Oncol 2022; 12:808757. [PMID: 35155245 PMCID: PMC8831698 DOI: 10.3389/fonc.2022.808757] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Accepted: 01/12/2022] [Indexed: 12/30/2022] Open
Abstract
Cells respond to DNA damage by activating signaling and DNA repair systems, described as the DNA damage response (DDR). Clarifying DDR pathways and their dysregulation in cancer are important for understanding cancer etiology, how cancer cells exploit the DDR to survive endogenous and treatment-related stress, and to identify DDR targets as therapeutic targets. Cancer is often treated with genotoxic chemicals and/or ionizing radiation. These agents are cytotoxic because they induce DNA double-strand breaks (DSBs) directly, or indirectly by inducing replication stress which causes replication fork collapse to DSBs. EEPD1 and Metnase are structure-specific nucleases, and Metnase is also a protein methyl transferase that methylates histone H3 and itself. EEPD1 and Metnase promote repair of frank, two-ended DSBs, and both promote the timely and accurate restart of replication forks that have collapsed to single-ended DSBs. In addition to its roles in HR, Metnase also promotes DSB repair by classical non-homologous recombination, and chromosome decatenation mediated by TopoIIα. Although mutations in Metnase and EEPD1 are not common in cancer, both proteins are frequently overexpressed, which may help tumor cells manage oncogenic stress or confer resistance to therapeutics. Here we focus on Metnase and EEPD1 DNA repair pathways, and discuss opportunities for targeting these pathways to enhance cancer therapy.
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Affiliation(s)
- Jac A Nickoloff
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO, United States
| | - Neelam Sharma
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO, United States
| | - Lynn Taylor
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO, United States
| | - Sage J Allen
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO, United States
| | - Suk-Hee Lee
- Department of Biochemistry & Molecular Biology, Indiana University School of Medicine, Indianapolis, IN, United States
| | - Robert Hromas
- Division of Hematology and Medical Oncology, Department of Medicine and the Mays Cancer Center, University of Texas Health Science Center, San Antonio, TX, United States
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6
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Lié O, Virolle T, Gabut M, Pasquier C, Zemmoura I, Augé-Gouillou C. SETMAR Shorter Isoform: A New Prognostic Factor in Glioblastoma. Front Oncol 2022; 11:638397. [PMID: 35047379 PMCID: PMC8761672 DOI: 10.3389/fonc.2021.638397] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Accepted: 11/03/2021] [Indexed: 12/27/2022] Open
Abstract
Recent evidence suggests that the chimeric protein SETMAR is a factor of interest in cancer, especially in glioblastoma. However, little is known about the expression of this protein in glioblastoma tissues, and no study has been done to assess if SETMAR could be a prognostic and/or diagnostic marker of glioblastoma. We analyzed protein extracts of 47 glioblastoma samples coming from a local and a national cohort of patients. From the local cohort, we obtained localized biopsies from the central necrosis area, the tumor, and the perilesional brain. From the French Glioblastoma Biobank (FGB), we obtained three types of samples: from the same tumors before and after treatment, from long survivors, and from very short survivors. We studied the correlations between SETMAR amounts, clinical profiles of patients and other associated proteins (PTN, snRNP70 and OLIG2). In glioblastoma tissues, the shorter isoform of SETMAR (S-SETMAR) was predominant over the full-length isoform (FL-SETMAR), and the expression of both SETMAR variants was higher in the tumor compared to the perilesional tissues. Data from the FGB showed that SETMAR amounts were not different between the initial tumors and tumor relapses after treatment. These data also showed a trend toward higher amounts of S-SETMAR in long survivors. In localized biopsies, we found a positive correlation between good prognosis and large amounts of S-SETMAR in the perilesional area. This is the main result presented here: survival in Glioblastoma is correlated with amounts of S-SETMAR in perilesional brain, which should be considered as a new relevant prognosis marker.
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Affiliation(s)
- Oriane Lié
- UMR 1253, iBrain, Université de Tours, Inserm, Tours, France
| | - Thierry Virolle
- Institut de Biologie Valrose, Université Côte D’Azur, CNRS, INSERM, Nice, France
| | - Mathieu Gabut
- INSERM 1052, CNRS 5286, Cancer Research Center of Lyon, Centre Léon Bérard, Lyon, France
- Université Claude Bernard Lyon 1, Villeurbanne, France
| | | | - Ilyess Zemmoura
- UMR 1253, iBrain, Université de Tours, Inserm, Tours, France
- Service de Neurochirurgie, CHRU de Tours, Tours, France
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7
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Miskei M, Horváth A, Viola L, Varga L, Nagy É, Feró O, Karányi Z, Roszik J, Miskey C, Ivics Z, Székvölgyi L. Genome-wide mapping of binding sites of the transposase-derived SETMAR protein in the human genome. Comput Struct Biotechnol J 2021; 19:4032-4041. [PMID: 34377368 PMCID: PMC8327481 DOI: 10.1016/j.csbj.2021.07.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Revised: 07/12/2021] [Accepted: 07/12/2021] [Indexed: 01/04/2023] Open
Abstract
Throughout evolution, DNA transposons provide a recurrent supply of genetic information to give rise to novel gene functions by fusion of their transposase domain to various domains of host-encoded proteins. One of these "domesticated", transposase-derived factors is SETMAR/Metnase which is a naturally occurring fusion protein that consists of a histone-lysine methyltransferase domain and an HsMar1 transposase. To elucidate the biological role of SETMAR, it is crucial to identify genomic targets to which SETMAR specifically binds and link these sites to the regulation of gene expression. Herein, we mapped the genomic landscape of SETMAR binding in a near-haploid human leukemia cell line (HAP1) in order to identify on-target and off-target binding sites at high resolution and to elucidate their role in terms of gene expression. Our analysis revealed a perfect correlation between SETMAR and inverted terminal repeats (ITRs) of HsMar1 transposon remnants, which are considered as natural target sites for SETMAR binding. However, we did not detect any untargeted events at non-ITR sequences, calling into question previously proposed off-target binding sites. We identified sequence fidelity of the ITR motif as a key factor for determining the binding affinity of SETMAR for chromosomes, as higher conservation of ITR sequences resulted in increased affinity for chromatin and stronger repression of SETMAR-bound gene loci. These associations highlight how SETMAR's chromatin binding fine-tune gene regulatory networks in human tumour cells.
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Affiliation(s)
- Márton Miskei
- MTA-DE Momentum Genome Architecture and Recombination Research Group, Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Debrecen, Hungary
| | - Adrienn Horváth
- MTA-DE Momentum Genome Architecture and Recombination Research Group, Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Debrecen, Hungary
| | - Lívia Viola
- MTA-DE Momentum Genome Architecture and Recombination Research Group, Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Debrecen, Hungary
| | - Laura Varga
- MTA-DE Momentum Genome Architecture and Recombination Research Group, Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Debrecen, Hungary
| | - Éva Nagy
- MTA-DE Momentum Genome Architecture and Recombination Research Group, Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Debrecen, Hungary
| | - Orsolya Feró
- MTA-DE Momentum Genome Architecture and Recombination Research Group, Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Debrecen, Hungary
| | - Zsolt Karányi
- MTA-DE Momentum Genome Architecture and Recombination Research Group, Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Debrecen, Hungary
- Department of Internal Medicine, Faculty of Medicine, University of Debrecen, Hungary
| | - Jason Roszik
- Department of Melanoma Medical Oncology, Division of Cancer Medicine, MD Anderson Cancer Centre, University of Texas, USA
| | - Csaba Miskey
- Division of Medical Biotechnology, Paul Ehrlich Institute, Langen D-63225, Germany
| | - Zoltán Ivics
- Division of Medical Biotechnology, Paul Ehrlich Institute, Langen D-63225, Germany
| | - Lóránt Székvölgyi
- MTA-DE Momentum Genome Architecture and Recombination Research Group, Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Debrecen, Hungary
- Faculty of Pharmacy, University of Debrecen, Hungary
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8
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Navas-Pérez E, Vicente-García C, Mirra S, Burguera D, Fernàndez-Castillo N, Ferrán JL, López-Mayorga M, Alaiz-Noya M, Suárez-Pereira I, Antón-Galindo E, Ulloa F, Herrera-Úbeda C, Cuscó P, Falcón-Moya R, Rodríguez-Moreno A, D'Aniello S, Cormand B, Marfany G, Soriano E, Carrión ÁM, Carvajal JJ, Garcia-Fernàndez J. Characterization of an eutherian gene cluster generated after transposon domestication identifies Bex3 as relevant for advanced neurological functions. Genome Biol 2020; 21:267. [PMID: 33100228 PMCID: PMC7586669 DOI: 10.1186/s13059-020-02172-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2020] [Accepted: 09/25/2020] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND One of the most unusual sources of phylogenetically restricted genes is the molecular domestication of transposable elements into a host genome as functional genes. Although these kinds of events are sometimes at the core of key macroevolutionary changes, their origin and organismal function are generally poorly understood. RESULTS Here, we identify several previously unreported transposable element domestication events in the human and mouse genomes. Among them, we find a remarkable molecular domestication that gave rise to a multigenic family in placental mammals, the Bex/Tceal gene cluster. These genes, which act as hub proteins within diverse signaling pathways, have been associated with neurological features of human patients carrying genomic microdeletions in chromosome X. The Bex/Tceal genes display neural-enriched patterns and are differentially expressed in human neurological disorders, such as autism and schizophrenia. Two different murine alleles of the cluster member Bex3 display morphological and physiopathological brain modifications, such as reduced interneuron number and hippocampal electrophysiological imbalance, alterations that translate into distinct behavioral phenotypes. CONCLUSIONS We provide an in-depth understanding of the emergence of a gene cluster that originated by transposon domestication and gene duplication at the origin of placental mammals, an evolutionary process that transformed a non-functional transposon sequence into novel components of the eutherian genome. These genes were integrated into existing signaling pathways involved in the development, maintenance, and function of the CNS in eutherians. At least one of its members, Bex3, is relevant for higher brain functions in placental mammals and may be involved in human neurological disorders.
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Affiliation(s)
- Enrique Navas-Pérez
- Department of Genetics, Microbiology and Statistics, Faculty of Biology, and Institut de Biomedicina (IBUB), University of Barcelona, 08028, Barcelona, Spain
| | - Cristina Vicente-García
- Centro Andaluz de Biología del Desarrollo, CSIC-UPO-JA, Universidad Pablo de Olavide, 41013, Sevilla, Spain
| | - Serena Mirra
- Department of Genetics, Microbiology and Statistics, Faculty of Biology, and Institut de Biomedicina (IBUB), University of Barcelona, 08028, Barcelona, Spain.,Department of Cell Biology, Physiology and Immunology, and Institute of Neurosciences, University of Barcelona, 08028, Barcelona, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III (ISCIII), Madrid, Spain.,Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Instituto de Salud Carlos III (ISCIII), 28029, Madrid, Spain
| | - Demian Burguera
- Department of Genetics, Microbiology and Statistics, Faculty of Biology, and Institut de Biomedicina (IBUB), University of Barcelona, 08028, Barcelona, Spain.,Department of Zoology, Charles University, Vinicna 7, 12844, Prague, Czech Republic
| | - Noèlia Fernàndez-Castillo
- Department of Genetics, Microbiology and Statistics, Faculty of Biology, and Institut de Biomedicina (IBUB), University of Barcelona, 08028, Barcelona, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III (ISCIII), Madrid, Spain.,Institut de Recerca Sant Joan de Déu (IR-SJD), Esplugues de Llobregat, 08950, Barcelona, Spain
| | - José Luis Ferrán
- Department of Human Anatomy, School of Medicine, University of Murcia and IMIB-Arrixaca Institute, 30120, Murcia, Spain
| | - Macarena López-Mayorga
- Centro Andaluz de Biología del Desarrollo, CSIC-UPO-JA, Universidad Pablo de Olavide, 41013, Sevilla, Spain
| | - Marta Alaiz-Noya
- Department of Physiology, Anatomy and Cell Biology, Universidad Pablo de Olavide, 41013, Sevilla, Spain.,Present Address: Instituto de Neurociencias de Alicante (Universidad Miguel Hernández - Consejo Superior de Investigaciones Científicas), Alicante, Spain
| | - Irene Suárez-Pereira
- Department of Physiology, Anatomy and Cell Biology, Universidad Pablo de Olavide, 41013, Sevilla, Spain.,Present Address: Centro de Investigación Biomédica en Red de Salud Mental (CIBERSAM), Neuropsychopharmacology and psychobiology research group, UCA, INiBICA, Cádiz, Spain
| | - Ester Antón-Galindo
- Department of Genetics, Microbiology and Statistics, Faculty of Biology, and Institut de Biomedicina (IBUB), University of Barcelona, 08028, Barcelona, Spain
| | - Fausto Ulloa
- Department of Cell Biology, Physiology and Immunology, and Institute of Neurosciences, University of Barcelona, 08028, Barcelona, Spain.,Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Instituto de Salud Carlos III (ISCIII), 28029, Madrid, Spain
| | - Carlos Herrera-Úbeda
- Department of Genetics, Microbiology and Statistics, Faculty of Biology, and Institut de Biomedicina (IBUB), University of Barcelona, 08028, Barcelona, Spain
| | - Pol Cuscó
- Genome Architecture, Gene Regulation, Stem Cells and Cancer Programme, Centre for Genomic Regulation (CRG), the Barcelona Institute of Science and Technology, 08003, Barcelona, Spain.,Universitat Pompeu Fabra (UPF), 08003, Barcelona, Spain
| | - Rafael Falcón-Moya
- Department of Physiology, Anatomy and Cell Biology, Universidad Pablo de Olavide, 41013, Sevilla, Spain
| | - Antonio Rodríguez-Moreno
- Department of Physiology, Anatomy and Cell Biology, Universidad Pablo de Olavide, 41013, Sevilla, Spain
| | - Salvatore D'Aniello
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, 80121, Naples, Italy
| | - Bru Cormand
- Department of Genetics, Microbiology and Statistics, Faculty of Biology, and Institut de Biomedicina (IBUB), University of Barcelona, 08028, Barcelona, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III (ISCIII), Madrid, Spain.,Institut de Recerca Sant Joan de Déu (IR-SJD), Esplugues de Llobregat, 08950, Barcelona, Spain
| | - Gemma Marfany
- Department of Genetics, Microbiology and Statistics, Faculty of Biology, and Institut de Biomedicina (IBUB), University of Barcelona, 08028, Barcelona, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III (ISCIII), Madrid, Spain.,Institut de Recerca Sant Joan de Déu (IR-SJD), Esplugues de Llobregat, 08950, Barcelona, Spain
| | - Eduardo Soriano
- Department of Cell Biology, Physiology and Immunology, and Institute of Neurosciences, University of Barcelona, 08028, Barcelona, Spain.,Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Instituto de Salud Carlos III (ISCIII), 28029, Madrid, Spain.,Institució Catalana de Recerca i Estudis Avançats (ICREA), 08010, Barcelona, Spain
| | - Ángel M Carrión
- Department of Physiology, Anatomy and Cell Biology, Universidad Pablo de Olavide, 41013, Sevilla, Spain
| | - Jaime J Carvajal
- Centro Andaluz de Biología del Desarrollo, CSIC-UPO-JA, Universidad Pablo de Olavide, 41013, Sevilla, Spain.
| | - Jordi Garcia-Fernàndez
- Department of Genetics, Microbiology and Statistics, Faculty of Biology, and Institut de Biomedicina (IBUB), University of Barcelona, 08028, Barcelona, Spain.
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9
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Dupeyron M, Baril T, Bass C, Hayward A. Phylogenetic analysis of the Tc1/mariner superfamily reveals the unexplored diversity of pogo-like elements. Mob DNA 2020; 11:21. [PMID: 32612713 PMCID: PMC7325037 DOI: 10.1186/s13100-020-00212-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Accepted: 04/08/2020] [Indexed: 01/18/2023] Open
Abstract
Background Tc1/mariner transposons are widespread DNA transposable elements (TEs) that have made important contributions to the evolution of host genomic complexity in metazoans. However, the evolution and diversity of the Tc1/mariner superfamily remains poorly understood. Following recent developments in genome sequencing and the availability of a wealth of new genomes, Tc1/mariner TEs have been identified in many new taxa across the eukaryotic tree of life. To date, the majority of studies focussing on Tc1/mariner elements have considered only a single host lineage or just a small number of host lineages. Thus, much remains to be learnt about the evolution of Tc1/mariner TEs by performing analyses that consider elements that originate from across host diversity. Results We mined the non-redundant database of NCBI using BLASTp searches, with transposase sequences from a diverse set of reference Tc1/mariner elements as queries. A total of 5158 Tc1/mariner elements were retrieved and used to reconstruct evolutionary relationships within the superfamily. The resulting phylogeny is well resolved and includes several new groups of Tc1/mariner elements. In particular, we identify a new family of plant-genome restricted Tc1/mariner elements, which we call PlantMar. We also show that the pogo family is much larger and more diverse than previously appreciated, and we review evidence for a potential revision of its status to become a separate superfamily. Conclusions Our study provides an overview of Tc1-mariner phylogeny and summarises the impressive diversity of Tc1-mariner TEs among sequenced eukaryotes. Tc1/mariner TEs are successful in a wide range of eukaryotes, especially unikonts (the taxonomic supergroup containing Amoebozoa, Opisthokonta, Breviatea, and Apusomonadida). In particular, ecdysozoa, and especially arthropods, emerge as important hosts for Tc1/mariner elements (except the PlantMar family). Meanwhile, the pogo family, which is by far the largest Tc1/mariner family, also includes many elements from fungal and chordate genomes. Moreover, there is evidence of the repeated exaptation of pogo elements in vertebrates, including humans, in addition to the well-known example of CENP-B. Collectively, our findings provide a considerable advancement in understanding of Tc1/mariner elements, and more generally they suggest that much work remains to improve understanding of the diversity and evolution of DNA TEs.
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Affiliation(s)
- Mathilde Dupeyron
- Centre for Ecology and Conservation, University of Exeter, Penryn Campus, Penryn, Cornwall, TR10 9FE UK
| | - Tobias Baril
- Centre for Ecology and Conservation, University of Exeter, Penryn Campus, Penryn, Cornwall, TR10 9FE UK
| | - Chris Bass
- Centre for Ecology and Conservation, University of Exeter, Penryn Campus, Penryn, Cornwall, TR10 9FE UK
| | - Alexander Hayward
- Centre for Ecology and Conservation, University of Exeter, Penryn Campus, Penryn, Cornwall, TR10 9FE UK
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10
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Bhatt S, Chalmers R. Targeted DNA transposition in vitro using a dCas9-transposase fusion protein. Nucleic Acids Res 2019; 47:8126-8135. [PMID: 31429873 PMCID: PMC6735945 DOI: 10.1093/nar/gkz552] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Revised: 06/07/2019] [Accepted: 06/11/2019] [Indexed: 12/21/2022] Open
Abstract
Homology-directed genome engineering is limited by transgene size. Although DNA transposons are more efficient with large transgenes, random integrations are potentially mutagenic. Here we present an in vitro mechanistic study that demonstrates efficient Cas9 targeting of the mariner transposon Hsmar1. Integrations were unidirectional and tightly constrained to one side of the sgRNA binding site. Further analysis of the nucleoprotein intermediates demonstrated that the transposase and Cas9 moieties can bind their respective substrates independently or in concert. Kinetic analysis of the reaction in the presence of the Cas9 target-DNA revealed a delay between first and second strand cleavage at the transposon end. This step involves a significant conformational change that may be hindered by the properties of the interdomainal linker. Otherwise, the transposase moiety behaved normally and was proficient for integration in vitro and in Escherichia coli. Specific integration into the lacZ gene in E. coli was obscured by a high background of random integrations. Nevertheless, Cas9 is an attractive candidate for transposon-targeting because it has a high affinity and long dwell-time at its target site. This will facilitate a future optogenetic strategy for the temporal control of integration, which will increase the ratio of targeted to untargeted events.
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Affiliation(s)
- Shivam Bhatt
- School of Life Sciences, University of Nottingham, Queen's Medical Centre, Nottingham NG7 2UH, UK
| | - Ronald Chalmers
- School of Life Sciences, University of Nottingham, Queen's Medical Centre, Nottingham NG7 2UH, UK
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11
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Palazzo A, Lorusso P, Miskey C, Walisko O, Gerbino A, Marobbio CMT, Ivics Z, Marsano RM. Transcriptionally promiscuous "blurry" promoters in Tc1/ mariner transposons allow transcription in distantly related genomes. Mob DNA 2019; 10:13. [PMID: 30988701 PMCID: PMC6446368 DOI: 10.1186/s13100-019-0155-6] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Accepted: 03/26/2019] [Indexed: 12/04/2022] Open
Abstract
Background We have recently described a peculiar feature of the promoters in two Drosophila Tc1-like elements, Bari1 and Bari3. The AT-richness and the presence of weak core-promoter motifs make these promoters, that we have defined “blurry”, able to activate transcription of a reporter gene in cellular systems as diverse as fly, human, yeast and bacteria. In order to clarify whether the blurry promoter is a specific feature of the Bari transposon family, we have extended this study to promoters isolated from three additional DNA transposon and from two additional LTR retrotransposons. Results Here we show that the blurry promoter is also a feature of two vertebrate transposable elements, Sleeping Beauty and Hsmar1, belonging to the Tc1/mariner superfamily. In contrast, this feature is not shared by the promoter of the hobo transposon, which belongs to the hAT superfamily, nor by LTR retrotransposon-derived promoters, which, in general, do not activate transcription when introduced into non-related genomes. Conclusions Our results suggest that the blurry promoter could be a shared feature of the members of the Tc1/mariner superfamily with possible evolutionary and biotechnological implications. Electronic supplementary material The online version of this article (10.1186/s13100-019-0155-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Antonio Palazzo
- 1Department of Biology, University of Bari "Aldo Moro", via Orabona 4, 70125 Bari, Italy.,Present address: Laboratory of Translational Nanotechnology, "Istituto Tumori Giovanni Paolo II" I.R.C.C.S, Viale Orazio Flacco 65, 70125 Bari, Italy
| | - Patrizio Lorusso
- 1Department of Biology, University of Bari "Aldo Moro", via Orabona 4, 70125 Bari, Italy
| | - Csaba Miskey
- 2Transposition and Genome Engineering, Division of Medical Biotechnology, Paul Ehrlich Institute, Langen, Germany
| | - Oliver Walisko
- 2Transposition and Genome Engineering, Division of Medical Biotechnology, Paul Ehrlich Institute, Langen, Germany
| | - Andrea Gerbino
- 3Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, 70125 Bari, Italy
| | | | - Zoltán Ivics
- 2Transposition and Genome Engineering, Division of Medical Biotechnology, Paul Ehrlich Institute, Langen, Germany
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12
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Simão MC, Haudry A, Granzotto A, de Setta N, Carareto CMA. Helena and BS: Two Travellers between the Genera Drosophila and Zaprionus. Genome Biol Evol 2018; 10:2671-2685. [PMID: 30165545 PMCID: PMC6179348 DOI: 10.1093/gbe/evy184] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/22/2018] [Indexed: 12/20/2022] Open
Abstract
The frequency of horizontal transfers of transposable elements (HTTs) varies among the types of elements according to the transposition mode and the geographical and temporal overlap of the species involved in the transfer. The drosophilid species of the genus Zaprionus and those of the melanogaster, obscura, repleta, and virilis groups of the genus Drosophila investigated in this study shared space and time at some point in their evolutionary history. This is particularly true of the subgenus Zaprionus and the melanogaster subgroup, which overlapped both geographically and temporally in Tropical Africa during their period of origin and diversification. Here, we tested the hypothesis that this overlap may have facilitated the transfer of retrotransposons without long terminal repeats (non-LTRs) between these species. We estimated the HTT frequency of the non-LTRs BS and Helena at the genome-wide scale by using a phylogenetic framework and a vertical and horizontal inheritance consistence analysis (VHICA). An excessively low synonymous divergence among distantly related species and incongruities between the transposable element and species phylogenies allowed us to propose at least four relatively recent HTT events of Helena and BS involving ancestors of the subgroup melanogaster and ancestors of the subgenus Zaprionus during their concomitant diversification in Tropical Africa, along with older possible events between species of the subgenera Drosophila and Sophophora. This study provides the first evidence for HTT of non-LTRs retrotransposons between Drosophila and Zaprionus, including an in-depth reconstruction of the time frame and geography of these events.
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Affiliation(s)
- Maryanna C Simão
- Universidade Estadual Paulista (Unesp), Instituto de Biociências Letras e Ciências Exatas (Ibilce), Câmpus São José do Rio Preto, SP, Brazil
| | - Annabelle Haudry
- Univ Lyon, Université Lyon 1, CNRS, Laboratoire de Biométrie et Biologie Evolutive, Villeurbanne, France
| | - Adriana Granzotto
- Universidade Estadual Paulista (Unesp), Instituto de Biociências Letras e Ciências Exatas (Ibilce), Câmpus São José do Rio Preto, SP, Brazil
| | - Nathalia de Setta
- Universidade Federal do ABC (UFABC), Centro de Ciências Naturais e Humanas (CCNH), São Bernardo do Campo, SP, Brazil
| | - Claudia M A Carareto
- Universidade Estadual Paulista (Unesp), Instituto de Biociências Letras e Ciências Exatas (Ibilce), Câmpus São José do Rio Preto, SP, Brazil
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13
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Preußer C, Hung LH, Schneider T, Schreiner S, Hardt M, Moebus A, Santoso S, Bindereif A. Selective release of circRNAs in platelet-derived extracellular vesicles. J Extracell Vesicles 2018; 7:1424473. [PMID: 29359036 PMCID: PMC5769804 DOI: 10.1080/20013078.2018.1424473] [Citation(s) in RCA: 161] [Impact Index Per Article: 26.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Accepted: 12/05/2017] [Indexed: 12/17/2022] Open
Abstract
Circular RNAs (circRNAs) are a novel class of noncoding RNAs present in all eukaryotic cells investigated so far and generated by a special mode of alternative splicing of pre-mRNAs. Thereby, single exons, or multiple adjacent and spliced exons, are released in a circular form. CircRNAs are cell-type specifically expressed, are unusually stable, and can be found in various body fluids such as blood and saliva. Here we analysed circRNAs and the corresponding linear splice isoforms from human platelets, where circRNAs are particularly abundant, compared with other hematopoietic cell types. In addition, we isolated extracellular vesicles from purified and in vitro activated human platelets, using density-gradient centrifugation, followed by RNA-seq analysis for circRNA detection. We could demonstrate that circRNAs are packaged and released within both types of vesicles (microvesicles and exosomes) derived from platelets. Interestingly, we observed a selective release of circRNAs into the vesicles, suggesting a specific sorting mechanism. In sum, circRNAs represent yet another class of extracellular RNAs that circulate in the body and may be involved in signalling pathways. Since platelets are essential for central physiological processes such as haemostasis, wound healing, inflammation and cancer metastasis, these findings should greatly extend the potential of circRNAs as prognostic and diagnostic biomarkers.
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Affiliation(s)
- Christian Preußer
- Institute of Biochemistry, Justus Liebig University of Giessen, Giessen, Germany
| | - Lee-Hsueh Hung
- Institute of Biochemistry, Justus Liebig University of Giessen, Giessen, Germany
| | - Tim Schneider
- Institute of Biochemistry, Justus Liebig University of Giessen, Giessen, Germany
| | - Silke Schreiner
- Institute of Biochemistry, Justus Liebig University of Giessen, Giessen, Germany
| | - Martin Hardt
- Biomedical Research Centre Seltersberg, Imaging Unit, Justus Liebig University of Giessen, Giessen, Germany
| | - Anna Moebus
- Biomedical Research Centre Seltersberg, Imaging Unit, Justus Liebig University of Giessen, Giessen, Germany
| | - Sentot Santoso
- Institute for Clinical Immunology and Transfusion Medicine, Justus Liebig University of Giessen, Giessen, Germany
| | - Albrecht Bindereif
- Institute of Biochemistry, Justus Liebig University of Giessen, Giessen, Germany
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14
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Dussaussois-Montagne A, Jaillet J, Babin L, Verrelle P, Karayan-Tapon L, Renault S, Rousselot-Denis C, Zemmoura I, Augé-Gouillou C. SETMAR isoforms in glioblastoma: A matter of protein stability. Oncotarget 2017; 8:9835-9848. [PMID: 28038463 PMCID: PMC5354774 DOI: 10.18632/oncotarget.14218] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Accepted: 12/05/2016] [Indexed: 01/10/2023] Open
Abstract
Glioblastomas (GBMs) are the most frequent and the most aggressive brain tumors, known for their chemo- and radio-resistance, making them often incurable. We also know that SETMAR is a protein involved in chromatin dynamics and genome plasticity, of which overexpression confers chemo- and radio-resistance to some tumors. The relationships between SETMAR and GBM have never been explored. To fill this gap, we define the SETMAR status of 44 resected tumors and of GBM derived cells, at both the mRNA and the protein levels. We identify a new, small SETMAR protein (so called SETMAR-1200), enriched in GBMs and GBM stem cells as compared to the regular enzyme (SETMAR-2100). We show that SETMAR-1200 is able to increase DNA repair by non-homologous end-joining, albeit with a lower efficiency than the regular SETMAR protein. Interestingly, the regular/small ratio of SETMAR in GBM cells changes depending on cell type, providing evidence that SETMAR expression is regulated by alternative splicing. We also demonstrate that SETMAR expression can be regulated by the use of an alternative ATG. In conclusion, various SETMAR proteins can be synthesized in human GBM that may each have specific biophysical and/or biochemical properties and characteristics. Among them, the small SETMAR may play a role in GBMs biogenesis. On this basis, we would like to consider SETMAR-1200 as a new potential therapeutic target to investigate, in addition to the regular SETMAR protein already considered by others.
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Affiliation(s)
| | - Jérôme Jaillet
- EA 6306 IGC, University François Rabelais, 37200 Tours, France
| | - Laetitia Babin
- EA 6306 IGC, University François Rabelais, 37200 Tours, France
- UMR CNRS 7292 GICC, University François Rabelais, 37000 Tours, France
| | - Pierre Verrelle
- EA 7283 CREaT, Université d′Auvergne, BP 10448, 63000 Clermont-Ferrand, France
- Institut Curie, Dpt d'Oncologie Radiothérapique, 75005 Paris, France
- Centre Jean Perrin, Service Radiothérapie, Laboratoire de Radio-Oncologie Expérimentale, 63000 Clermont-Ferrand, France
| | - Lucie Karayan-Tapon
- INSERM U1084, Laboratoire de Neurosciences Expérimentales et Cliniques, F-86021 Poitiers, France
- University of Poitiers, F-86022 Poitiers, France
- CHU of Poitiers, Laboratoire de Cancérologie Biologique, F-86021 Poitiers, France
| | | | | | - Ilyess Zemmoura
- INSERM U930 Imagerie & Cerveau, University François Rabelais, 37000 Tours, France
- CHRU of Tours, Service de Neurochirurgie, 37000 Tours, France
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15
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Wang Y, Pryputniewicz-Dobrinska D, Nagy EÉ, Kaufman CD, Singh M, Yant S, Wang J, Dalda A, Kay MA, Ivics Z, Izsvák Z. Regulated complex assembly safeguards the fidelity of Sleeping Beauty transposition. Nucleic Acids Res 2016; 45:311-326. [PMID: 27913727 PMCID: PMC5224488 DOI: 10.1093/nar/gkw1164] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Revised: 11/03/2016] [Accepted: 11/16/2016] [Indexed: 01/21/2023] Open
Abstract
The functional relevance of the inverted repeat structure (IR/DR) in a subgroup of the Tc1/mariner superfamily of transposons has been enigmatic. In contrast to mariner transposition, where a topological filter suppresses single-ended reactions, the IR/DR orchestrates a regulatory mechanism to enforce synapsis of the transposon ends before cleavage by the transposase occurs. This ordered assembly process shepherds primary transposase binding to the inner 12DRs (where cleavage does not occur), followed by capture of the 12DR of the other transposon end. This extra layer of regulation suppresses aberrant, potentially genotoxic recombination activities, and the mobilization of internally deleted copies in the IR/DR subgroup, including Sleeping Beauty (SB). In contrast, internally deleted sequences (MITEs) are preferred substrates of mariner transposition, and this process is associated with the emergence of Hsmar1-derived miRNA genes in the human genome. Translating IR/DR regulation to in vitro evolution yielded an SB transposon version with optimized substrate recognition (pT4). The ends of SB transposons excised by a K248A excision+/integration- transposase variant are processed by hairpin resolution, representing a link between phylogenetically, and mechanistically different recombination reactions, such as V(D)J recombination and transposition. Such variants generated by random mutation might stabilize transposon-host interactions or prepare the transposon for a horizontal transfer.
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Affiliation(s)
- Yongming Wang
- Max-Delbrück-Center for Molecular Medicine in the Helmholtz Society, Berlin 13125, Germany
| | | | - Enikö Éva Nagy
- Max-Delbrück-Center for Molecular Medicine in the Helmholtz Society, Berlin 13125, Germany
| | - Christopher D Kaufman
- Max-Delbrück-Center for Molecular Medicine in the Helmholtz Society, Berlin 13125, Germany
| | - Manvendra Singh
- Max-Delbrück-Center for Molecular Medicine in the Helmholtz Society, Berlin 13125, Germany
| | - Steve Yant
- Departments of Pediatrics and Genetics, Stanford University, Stanford, CA 94305-5164, USA
| | - Jichang Wang
- Max-Delbrück-Center for Molecular Medicine in the Helmholtz Society, Berlin 13125, Germany
| | - Anna Dalda
- Max-Delbrück-Center for Molecular Medicine in the Helmholtz Society, Berlin 13125, Germany
| | - Mark A Kay
- Departments of Pediatrics and Genetics, Stanford University, Stanford, CA 94305-5164, USA
| | - Zoltán Ivics
- Division of Medical Biotechnology, Paul-Ehrlich-Institute, Langen 63225, Germany
| | - Zsuzsanna Izsvák
- Max-Delbrück-Center for Molecular Medicine in the Helmholtz Society, Berlin 13125, Germany
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16
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Chen Q, Georgiadis M. Crystallization of and selenomethionine phasing strategy for a SETMAR-DNA complex. Acta Crystallogr F Struct Biol Commun 2016; 72:713-9. [PMID: 27599863 PMCID: PMC5012212 DOI: 10.1107/s2053230x16012723] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Accepted: 08/06/2016] [Indexed: 11/10/2022] Open
Abstract
Transposable elements have played a critical role in the creation of new genes in all higher eukaryotes, including humans. Although the chimeric fusion protein SETMAR is no longer active as a transposase, it contains both the DNA-binding domain (DBD) and catalytic domain of the Hsmar1 transposase. The amino-acid sequence of the DBD has been virtually unchanged in 50 million years and, as a consequence, SETMAR retains its sequence-specific binding to the ancestral Hsmar1 terminal inverted repeat (TIR) sequence. Thus, the DNA-binding activity of SETMAR is likely to have an important biological function. To determine the structural basis for the recognition of TIR DNA by SETMAR, the design of TIR-containing oligonucleotides and SETMAR DBD variants, crystallization of DBD-DNA complexes, phasing strategies and initial phasing experiments are reported here. An unexpected finding was that oligonucleotides containing two BrdUs in place of thymidines produced better quality crystals in complex with SETMAR than their natural counterparts.
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Affiliation(s)
- Qiujia Chen
- Biochemistry and Molecular Biology, Indiana University School of Medicine, 635 Barnhill Drive, Indianapolis, IN 46202, USA
| | - Millie Georgiadis
- Biochemistry and Molecular Biology, Indiana University School of Medicine, 635 Barnhill Drive, Indianapolis, IN 46202, USA
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17
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Abstract
The IS630-Tc1-mariner (ITm) family of transposons is one of the most widespread in nature. The phylogenetic distribution of its members shows that they do not persist for long in a given lineage, but rely on frequent horizontal transfer to new hosts. Although they are primarily selfish genomic-parasites, ITm transposons contribute to the evolution of their hosts because they generate variation and contribute protein domains and regulatory regions. Here we review the molecular mechanism of ITm transposition and its regulation. We focus mostly on the mariner elements, which are understood in the greatest detail owing to in vitro reconstitution and structural analysis. Nevertheless, the most important characteristics are probably shared across the grouping. Members of the ITm family are mobilized by a cut-and-paste mechanism and integrate at 5'-TA dinucleotide target sites. The elements encode a single transposase protein with an N-terminal DNA-binding domain and a C-terminal catalytic domain. The phosphoryl-transferase reactions during the DNA-strand breaking and joining reactions are performed by the two metal-ion mechanism. The metal ions are coordinated by three or four acidic amino acid residues located within an RNase H-like structural fold. Although all of the strand breaking and joining events at a given transposon end are performed by a single molecule of transposase, the reaction is coordinated by close communication between transpososome components. During transpososome assembly, transposase dimers compete for free transposon ends. This helps to protect the host by dampening an otherwise exponential increase in the rate of transposition as the copy number increases.
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18
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Bire S, Casteret S, Piégu B, Beauclair L, Moiré N, Arensbuger P, Bigot Y. Mariner Transposons Contain a Silencer: Possible Role of the Polycomb Repressive Complex 2. PLoS Genet 2016; 12:e1005902. [PMID: 26939020 PMCID: PMC4777549 DOI: 10.1371/journal.pgen.1005902] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Accepted: 02/05/2016] [Indexed: 12/31/2022] Open
Abstract
Transposable elements are driving forces for establishing genetic innovations such as transcriptional regulatory networks in eukaryotic genomes. Here, we describe a silencer situated in the last 300 bp of the Mos1 transposase open reading frame (ORF) which functions in vertebrate and arthropod cells. Functional silencers are also found at similar locations within three other animal mariner elements, i.e. IS630-Tc1-mariner (ITm) DD34D elements, Himar1, Hsmar1 and Mcmar1. These silencers are able to impact eukaryotic promoters monitoring strong, moderate or low expression as well as those of mariner elements located upstream of the transposase ORF. We report that the silencing involves at least two transcription factors (TFs) that are conserved within animal species, NFAT-5 and Alx1. These cooperatively act with YY1 to trigger the silencing activity. Four other housekeeping transcription factors (TFs), neuron restrictive silencer factor (NRSF), GAGA factor (GAF) and GTGT factor (GTF), were also found to have binding sites within mariner silencers but their impact in modulating the silencer activity remains to be further specified. Interestingly, an NRSF binding site was found to overlap a 30 bp motif coding a highly conserved PHxxYSPDLAPxD peptide in mariner transposases. We also present experimental evidence that silencing is mainly achieved by co-opting the host Polycomb Repressive Complex 2 pathway. However, we observe that when PRC2 is impaired another host silencing pathway potentially takes over to maintain weak silencer activity. Mariner silencers harbour features of Polycomb Response Elements, which are probably a way for mariner elements to self-repress their transcription and mobility in somatic and germinal cells when the required TFs are expressed. At the evolutionary scale, mariner elements, through their exaptation, might have been a source of silencers playing a role in the chromatin configuration in eukaryotic genomes. Transposons are mobile DNA sequences that have long co-evolved with the genome of their hosts. Consequently, they are involved in the generation of mutations, as well as the creation of genes and regulatory networks. Controlling the transposon activity, and consequently its negative effects on both the host soma and germ line, is a challenge for the survival of both the host and the transposon. To silence transposons, hosts often use defence mechanisms involving DNA methylation and RNA interference pathways. Here we show that mariner transposons can self-regulate their activity by using a silencer element located in their DNA sequence. The silencer element interferes with host housekeeping protein transcription factors involved in the polycomb silencing pathways. As the regulation of chromatin configuration by polycomb is an important regulator of animal development, our findings open the possibility that mariner silencers might have been exapted during animal evolution to participate in certain regulation pathways of their hosts. Since some of the TFs involved in mariner silencer activity play a role at different stages of nervous system development and neuron differentiation, it might be possible that mariner transposons can be active during some steps of cell differentiation. Interestingly, mariner transposons (i.e. IS630-Tc1-mariner (ITm) DD34D transposons) have so far only been found in genomes of animals having a nervous system.
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Affiliation(s)
- Solenne Bire
- PRC, UMR INRA-CNRS 7247, PRC, Nouzilly, France
- Institute of Biotechnology, University of Lausanne, and Center for Biotechnology UNIL-EPFL, Lausanne, Switzerland
| | | | | | | | | | - Peter Arensbuger
- Biological Sciences Department, California State Polytechnic University, Pomona, California, United States of America
| | - Yves Bigot
- PRC, UMR INRA-CNRS 7247, PRC, Nouzilly, France
- * E-mail:
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19
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Tc1-like Transposase Thm3 of Silver Carp (Hypophthalmichthys molitrix) Can Mediate Gene Transposition in the Genome of Blunt Snout Bream (Megalobrama amblycephala). G3-GENES GENOMES GENETICS 2015; 5:2601-10. [PMID: 26438298 PMCID: PMC4683633 DOI: 10.1534/g3.115.020933] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Tc1-like transposons consist of an inverted repeat sequence flanking a transposase gene that exhibits similarity to the mobile DNA element, Tc1, of the nematode, Caenorhabditis elegans. They are widely distributed within vertebrate genomes including teleost fish; however, few active Tc1-like transposases have been discovered. In this study, 17 Tc1-like transposon sequences were isolated from 10 freshwater fish species belonging to the families Cyprinidae, Adrianichthyidae, Cichlidae, and Salmonidae. We conducted phylogenetic analyses of these sequences using previously isolated Tc1-like transposases and report that 16 of these elements comprise a new subfamily of Tc1-like transposons. In particular, we show that one transposon, Thm3 from silver carp (Hypophthalmichthys molitrix; Cyprinidae), can encode a 335-aa transposase with apparently intact domains, containing three to five copies in its genome. We then coinjected donor plasmids harboring 367 bp of the left end and 230 bp of the right end of the nonautonomous silver carp Thm1 cis-element along with capped Thm3 transposase RNA into the embryos of blunt snout bream (Megalobrama amblycephala; one- to two-cell embryos). This experiment revealed that the average integration rate could reach 50.6% in adult fish. Within the blunt snout bream genome, the TA dinucleotide direct repeat, which is the signature of Tc1-like family of transposons, was created adjacent to both ends of Thm1 at the integration sites. Our results indicate that the silver carp Thm3 transposase can mediate gene insertion by transposition within the genome of blunt snout bream genome, and that this occurs with a TA position preference.
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20
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Hoen DR, Bureau TE. Discovery of novel genes derived from transposable elements using integrative genomic analysis. Mol Biol Evol 2015; 32:1487-506. [PMID: 25713212 DOI: 10.1093/molbev/msv042] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Complex eukaryotes contain millions of transposable elements (TEs), comprising large fractions of their nuclear genomes. TEs consist of structural, regulatory, and coding sequences that are ordinarily associated with transposition, but that occasionally confer on the organism a selective advantage and may thereby become exapted. Exapted transposable element genes (ETEs) are known to play critical roles in diverse systems, from vertebrate adaptive immunity to plant development. Yet despite their evident importance, most ETEs have been identified fortuitously and few systematic searches have been conducted, suggesting that additional ETEs may await discovery. To explore this possibility, we develop a comprehensive systematic approach to searching for ETEs. We use TE-specific conserved domains to identify with high precision genes derived from TEs and screen them for signatures of exaptation based on their similarities to reference sets of known ETEs, conventional (non-TE) genes, and TE genes across diverse genetic attributes including repetitiveness, conservation of genomic location and sequence, and levels of expression and repressive small RNAs. Applying this approach in the model plant Arabidopsis thaliana, we discover a surprisingly large number of novel high confidence ETEs. Intriguingly, unlike known plant ETEs, several of the novel ETE families form tandemly arrayed gene clusters, whereas others are relatively young. Our results not only identify novel TE-derived genes that may have practical applications but also challenge the notion that TE exaptation is merely a relic of ancient life, instead suggesting that it may continue to fundamentally drive evolution.
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Affiliation(s)
- Douglas R Hoen
- Department of Biology, McGill University, Montréal, QC, Canada
| | - Thomas E Bureau
- Department of Biology, McGill University, Montréal, QC, Canada
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21
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Kharrat I, Mezghani M, Casse N, Denis F, Caruso A, Makni H, Capy P, Rouault JD, Chénais B, Makni M. Characterization of mariner-like transposons of the mauritiana Subfamily in seven tree aphid species. Genetica 2015; 143:63-72. [PMID: 25555688 DOI: 10.1007/s10709-014-9814-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2014] [Accepted: 12/26/2014] [Indexed: 11/26/2022]
Abstract
Mariner-like elements (MLEs) are Class II transposons present in all eukaryotic genomes in which MLEs have been searched for. This article reports the detection of MLEs in seven of the main fruit tree aphid species out of eight species studied. Deleted MLE sequences of 916-919 bp were characterized, using the terminal-inverted repeats (TIRs) of mariner elements belonging to the mauritiana Subfamily as primers. All the sequences detected were deleted copies of full-length elements that included the 3'- and 5'-TIRs but displayed internal deletions affecting Mos1 activity. Networks based on the mtDNA cytochrome oxidase subunit-I (CO-I) and MLE sequences were incongruent, suggesting that mutations in transposon sequences had accumulated before speciation of tree aphid species occurred, and that they have been maintained in this species via vertical transmissions. This is the first evidence of the widespread occurrence of MLEs in aphids.
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Affiliation(s)
- Imen Kharrat
- Faculté des Sciences de Tunis, Université de Tunis El Manar, UR11ES10 Génomique des insectes ravageurs, 2092, Manar II, Tunisia
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22
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Wolkowicz U, Morris ER, Robson M, Trubitsyna M, Richardson JM. Structural basis of Mos1 transposase inhibition by the anti-retroviral drug Raltegravir. ACS Chem Biol 2014; 9:743-51. [PMID: 24397848 PMCID: PMC3977574 DOI: 10.1021/cb400791u] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Accepted: 01/07/2014] [Indexed: 11/28/2022]
Abstract
DNA transposases catalyze the movement of transposons around genomes by a cut-and-paste mechanism related to retroviral integration. Transposases and retroviral integrases share a common RNaseH-like domain with a catalytic DDE/D triad that coordinates the divalent cations required for DNA cleavage and integration. The anti-retroviral drugs Raltegravir and Elvitegravir inhibit integrases by displacing viral DNA ends from the catalytic metal ions. We demonstrate that Raltegravir, but not Elvitegravir, binds to Mos1 transposase in the presence of Mg(2+) or Mn(2+), without the requirement for transposon DNA, and inhibits transposon cleavage and DNA integration in biochemical assays. Crystal structures at 1.7 Å resolution show Raltegravir, in common with integrases, coordinating two Mg(2+) or Mn(2+) ions in the Mos1 active site. However, in the absence of transposon ends, the drug adopts an unusual, compact binding mode distinct from that observed in the active site of the prototype foamy virus integrase.
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Affiliation(s)
- Urszula
M. Wolkowicz
- School of Biological Sciences, University
of Edinburgh, Mayfield
Road, Edinburgh EH9 3JR, United Kingdom
| | - Elizabeth R. Morris
- School of Biological Sciences, University
of Edinburgh, Mayfield
Road, Edinburgh EH9 3JR, United Kingdom
| | - Michael Robson
- School of Biological Sciences, University
of Edinburgh, Mayfield
Road, Edinburgh EH9 3JR, United Kingdom
| | - Maryia Trubitsyna
- School of Biological Sciences, University
of Edinburgh, Mayfield
Road, Edinburgh EH9 3JR, United Kingdom
| | - Julia M. Richardson
- School of Biological Sciences, University
of Edinburgh, Mayfield
Road, Edinburgh EH9 3JR, United Kingdom
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Jeyaratnam DC, Baduin BS, Hansen MC, Hansen M, Jørgensen JM, Aggerholm A, Ommen HB, Hokland P, Nyvold CG. Delineation of known and new transcript variants of the SETMAR (Metnase) gene and the expression profile in hematologic neoplasms. Exp Hematol 2014; 42:448-56.e4. [PMID: 24607956 DOI: 10.1016/j.exphem.2014.02.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2013] [Revised: 02/11/2014] [Accepted: 02/25/2014] [Indexed: 12/23/2022]
Abstract
SET domain and mariner transposase fusion gene (SETMAR), also known as Metnase, has previously been shown to suppress the formation of chromosomal translocation in mouse fibroblasts. Despite the fact that hematologic malignancies are often characterized by chromosomal rearrangements, no studies have hitherto investigated the expression pattern of the gene in these disorders. We hypothesized that a high expression of SETMAR protected the cells from chromosomal rearrangements; thus, we examined the mRNA expression of SETMAR transcript variants in hematologic patients. We identified six transcript variants (var1, var2, var5, varA, varB, varC), of which three had not been reported previously. Expression levels were quantified by transcript-specific quantitative polymerase chain reaction in 15 healthy individuals, 70 acute myeloid leukemia (AML) patients (translocation positive, n= 30 [AML(TPos)], translocation negative, n = 40 [AML(TNeg)]), seven patients with mantle cell lymphoma (t [11,14] positive), and 13 patients with chronic myeloid leukemia (t [9,22] positive). All variants were significantly overexpressed in both subgroups of AML compared with healthy individuals (var1 and var2: p < 0.00001 for both AML subgroups, varA and varB: p = 0.0002, var5: p = 0.0008, and varC: p = 0.0001 for AML(TNeg); varA: p = 0.0048, varB and var5: p = 0.0001, varC: p = 0.0017). When comparing the expression in AML(TNeg) and AML(TPos), we found a significantly increased expression of the full length SETMAR in AML(TNeg) (var1: p = 0.047), suggesting a protective effect of high SETMAR expression on formation of chromosomal translocations. In conclusion, we have found known and novel SETMAR splice variants to be significantly increased in AML. To our knowledge, this is the first study that describes an expression profile of SETMAR in subgroups of hematologic malignancies, which can be linked to the incidence of chromosomal rearrangements.
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Affiliation(s)
| | | | | | - Maria Hansen
- Department of Hematology, Aarhus University Hospital, Aarhus, Denmark
| | | | - Anni Aggerholm
- Department of Hematology, Aarhus University Hospital, Aarhus, Denmark
| | - Hans Beier Ommen
- Department of Hematology, Aarhus University Hospital, Aarhus, Denmark
| | - Peter Hokland
- Department of Hematology, Aarhus University Hospital, Aarhus, Denmark
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24
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Kim HS, Chen Q, Kim SK, Nickoloff JA, Hromas R, Georgiadis MM, Lee SH. The DDN catalytic motif is required for Metnase functions in non-homologous end joining (NHEJ) repair and replication restart. J Biol Chem 2014; 289:10930-10938. [PMID: 24573677 PMCID: PMC4036204 DOI: 10.1074/jbc.m113.533216] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Metnase (or SETMAR) arose from a chimeric fusion of the Hsmar1 transposase downstream of a protein methylase in anthropoid primates. Although the Metnase transposase domain has been largely conserved, its catalytic motif (DDN) differs from the DDD motif of related transposases, which may be important for its role as a DNA repair factor and its enzymatic activities. Here, we show that substitution of DDN610 with either DDD610 or DDE610 significantly reduced in vivo functions of Metnase in NHEJ repair and accelerated restart of replication forks. We next tested whether the DDD or DDE mutants cleave single-strand extensions and flaps in partial duplex DNA and pseudo-Tyr structures that mimic stalled replication forks. Neither substrate is cleaved by the DDD or DDE mutant, under the conditions where wild-type Metnase effectively cleaves ssDNA overhangs. We then characterized the ssDNA-binding activity of the Metnase transposase domain and found that the catalytic domain binds ssDNA but not dsDNA, whereas dsDNA binding activity resides in the helix-turn-helix DNA binding domain. Substitution of Asn-610 with either Asp or Glu within the transposase domain significantly reduces ssDNA binding activity. Collectively, our results suggest that a single mutation DDN610 → DDD610, which restores the ancestral catalytic site, results in loss of function in Metnase.
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Affiliation(s)
- Hyun-Suk Kim
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana 46202
| | - Qiujia Chen
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana 46202
| | - Sung-Kyung Kim
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana 46202
| | - Jac A Nickoloff
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, Colorado 80523
| | - Robert Hromas
- Department of Medicine, University of Florida and Shands Health Care System, Gainesville, Florida 32610
| | - Millie M Georgiadis
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana 46202; Department of Chemistry and Chemical Biology, Indiana University Purdue University Indianapolis, Indianapolis, Indiana 46202
| | - Suk-Hee Lee
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana 46202.
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25
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Galaktionov NK, Solovyeva AI, Fedorov AV, Podgornaya OI. Trematode Himasthla elongata mariner element (Hemar): structure and applications. JOURNAL OF EXPERIMENTAL ZOOLOGY PART B-MOLECULAR AND DEVELOPMENTAL EVOLUTION 2014; 322:142-55. [PMID: 24376187 DOI: 10.1002/jez.b.22553] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2013] [Accepted: 11/19/2013] [Indexed: 11/08/2022]
Abstract
We cloned and analyzed Hemar1-the full-length mariner of Himasthla elongata. Hemar1 amount and distribution in the genome is typical for the transposable elements. Hemar1 closest relatives found in databases are the mariner-like element (MLE) of Girardia tigrina with 88% similarity in the most conserved transposase domain and Cemar1 of Caenorhabditis elegans with the most similar inverted terminal repeats. Hydra's (Cnidaria) MLE are the next in similarity to Hemar1. We checked whether sequences similar to Hemar1 exist in intermediate and definitive hosts of the parasitic trematode and did not find obvious similarity. This fact, together with the data of Hemar1 evolutionary position, argues against recent MLE-mediated horizontal transfer in this parasite-host model. Our results demonstrate that H. elongata generates genomic variability in asexual parthenogenetic generations within the snail. Transposon insertional display based on full-length sequence showed that Hemar1 could be located in the regions involved in generating clonal diversity in rediae and cercariae, that is, trematode parthenitae.
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Affiliation(s)
- Nick K Galaktionov
- Department of Cytology and Histology, Faculty of Biology, St. Petersburg State University, St. Petersburg, Russia
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26
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Oliveira SG, Cabral-de-Mello DC, Moura RC, Martins C. Chromosomal organization and evolutionary history of Mariner transposable elements in Scarabaeinae coleopterans. Mol Cytogenet 2013; 6:54. [PMID: 24286129 PMCID: PMC3906913 DOI: 10.1186/1755-8166-6-54] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2013] [Accepted: 10/25/2013] [Indexed: 01/09/2023] Open
Abstract
Background With the aim to increase the knowledge on the evolution of coleopteran genomes, we investigated through cytogenetics and nucleotide sequence analysis Mariner transposons in three Scarabaeinae species (Coprophanaeus cyanescens, C. ensifer and Diabroctis mimas). Results The cytogenetic mapping revealed an accumulation of Mariner transposon in the pericentromeric repetitive regions characterized as rich in heterochromatin and C0t-1 DNA fraction (DNA enriched with high and moderately repeated sequences). Nucleotide sequence analysis of Mariner revealed the presence of two major groups of Mariner copies in the three investigated coleoptera species. Conclusions The Mariner is accumulated in the centromeric area of the coleopteran chromosomes probably as a consequence of the absence of recombination in the heterochromatic regions. Our analysis detected high diversification of Mariner sequences during the evolutionary history of the group. Furthermore, comparisons between the coleopterans sequences with other insects and mammals, suggest that the horizontal transfer (HT) could have acted in the spreading of the Mariner in diverse non-related animal groups.
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Affiliation(s)
| | | | | | - Cesar Martins
- Morphology Department, Biosciences Institute, UNESP - São Paulo State University, Botucatu, SP 18618-970, Brazil.
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The functional interactome landscape of the human histone deacetylase family. Mol Syst Biol 2013; 9:672. [PMID: 23752268 PMCID: PMC3964310 DOI: 10.1038/msb.2013.26] [Citation(s) in RCA: 218] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2013] [Accepted: 04/29/2013] [Indexed: 12/22/2022] Open
Abstract
This study presents the first global protein interaction network for all 11 human HDACs in T cells and an integrative mass spectrometry approach for profiling relative interaction stability within isolated protein complexes. ![]()
T-cell lines stably expressing each of the human HDACs (1 - 11), C-terminally tagged with both EGFP and FLAG, were generated using retroviral transduction. Affinity purification coupled to mass spectrometry-based proteomics (AP-MS) was used to build the first global protein interaction network for all eleven human HDACs in T cells. An optimized label free AP-MS and computational workflow was developed for profiling relative interaction stability among isolated protein complexes. HDAC11 is a member of the “survival of motor neuron” protein complex with a functional role in mRNA splicing.
Histone deacetylases (HDACs) are a diverse family of essential transcriptional regulatory enzymes, that function through the spatial and temporal recruitment of protein complexes. As the composition and regulation of HDAC complexes are only partially characterized, we built the first global protein interaction network for all 11 human HDACs in T cells. Integrating fluorescence microscopy, immunoaffinity purifications, quantitative mass spectrometry, and bioinformatics, we identified over 200 unreported interactions for both well-characterized and lesser-studied HDACs, a subset of which were validated by orthogonal approaches. We establish HDAC11 as a member of the survival of motor neuron complex and pinpoint a functional role in mRNA splicing. We designed a complementary label-free and metabolic-labeling mass spectrometry-based proteomics strategy for profiling interaction stability among different HDAC classes, revealing that HDAC1 interactions within chromatin-remodeling complexes are largely stable, while transcription factors preferentially exist in rapid equilibrium. Overall, this study represents a valuable resource for investigating HDAC functions in health and disease, encompassing emerging themes of HDAC regulation in cell cycle and RNA processing and a deeper functional understanding of HDAC complex stability.
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Claeys Bouuaert C, Lipkow K, Andrews SS, Liu D, Chalmers R. The autoregulation of a eukaryotic DNA transposon. eLife 2013; 2:e00668. [PMID: 23795293 PMCID: PMC3687335 DOI: 10.7554/elife.00668] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2013] [Accepted: 05/13/2013] [Indexed: 01/03/2023] Open
Abstract
How do DNA transposons live in harmony with their hosts? Bacteria provide the only documented mechanisms for autoregulation, but these are incompatible with eukaryotic cell biology. Here we show that autoregulation of Hsmar1 operates during assembly of the transpososome and arises from the multimeric state of the transposase, mediated by a competition for binding sites. We explore the dynamics of a genomic invasion using a computer model, supported by in vitro and in vivo experiments, and show that amplification accelerates at first but then achieves a constant rate. The rate is proportional to the genome size and inversely proportional to transposase expression and its affinity for the transposon ends. Mariner transposons may therefore resist post-transcriptional silencing. Because regulation is an emergent property of the reaction it is resistant to selfish exploitation. The behavior of distantly related eukaryotic transposons is consistent with the same mechanism, which may therefore be widely applicable. DOI:http://dx.doi.org/10.7554/eLife.00668.001 Transposons are regions of mobile DNA that can jump from one location in the genome to another. This represents a genetic burden to the host because there is always the risk that the transposon will inactivate a cellular gene. However, a greater problem is that transposition is accompanied by an increase in the number of copies of the transposon. Since each new copy will be a source of further new copies, amplification of transposons is necessarily exponential. The fact that eukaryotic cells are able to tolerate DNA transposons suggests the existence of regulatory mechanisms to defuse the inevitable genomic melt-down. Host-mediated epigenetic modifications and RNA interference will provide some level of protection. However, they are by no means completely effective and a well-adapted genomic parasite, such as a transposon, might be expected to have its own mechanism of regulation. Now, Claeys Bouuaert, Lipkow and colleagues have used a computer model in combination with in vivo and in vitro experiments to search for this mechanism. Their experiments reveal how a DNA transposon is down-regulated by its own transposase. The transposase is the enzyme that catalyzes the ‘jump’ or transposition. It binds to specific sites at either end of the transposon and brings these together to make up a nucleoprotein complex called the transpososome. It is within this complex that the chemical steps of the reaction take place. When the number of transposons increases, so does the concentration of transposase. Claeys Bouuaert et al. show that the binding sites become saturated at a relatively low transposase concentration and that negative regulation arises from the resulting competition. Thus, the rate of transposition decreases as the number of transposons increases. They further use the computer model to explore how the amplification of the transposon is affected by transposon-specific and cellular-specific factors. Claeys Bouuaert, Lipkow and colleagues based their study predominantly on a resurrected copy of the Hsmar1 transposon, which was active in the human genome 50 million years ago. However, they also tested two distantly related eukaryotic transposons and observed that their behavior was similar, which suggests that this could be a general mechanism that controls the activity of jumping genes. They also note that their competition mechanism is conceptually similar to the immunological ‘prozone effect’. This is a recurrent theme in protein chemistry and demonstrates once again that less is in fact sometimes more. DOI:http://dx.doi.org/10.7554/eLife.00668.002
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29
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Claeys Bouuaert C, Chalmers R. Hsmar1 transposition is sensitive to the topology of the transposon donor and the target. PLoS One 2013; 8:e53690. [PMID: 23341977 PMCID: PMC3544897 DOI: 10.1371/journal.pone.0053690] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2012] [Accepted: 12/04/2012] [Indexed: 01/08/2023] Open
Abstract
Hsmar1 is a member of the Tc1-mariner superfamily of DNA transposons. These elements mobilize within the genome of their host by a cut-and-paste mechanism. We have exploited the in vitro reaction provided by Hsmar1 to investigate the effect of DNA supercoiling on transposon integration. We found that the topology of both the transposon and the target affect integration. Relaxed transposons have an integration defect that can be partially restored in the presence of elevated levels of negatively supercoiled target DNA. Negatively supercoiled DNA is a better target than nicked or positively supercoiled DNA, suggesting that underwinding of the DNA helix promotes target interactions. Like other Tc1-mariner elements, Hsmar1 integrates into 5′-TA dinucleotides. The direct vicinity of the target TA provides little sequence specificity for target interactions. However, transposition within a plasmid substrate was not random and some TA dinucleotides were targeted preferentially. The distribution of intramolecular target sites was not affected by DNA topology.
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30
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Williamson EA, Damiani L, Leitao A, Hu C, Hathaway H, Oprea T, Sklar L, Shaheen M, Bauman J, Wang W, Nickoloff JA, Lee SH, Hromas R. Targeting the transposase domain of the DNA repair component Metnase to enhance chemotherapy. Cancer Res 2012; 72:6200-8. [PMID: 23090115 DOI: 10.1158/0008-5472.can-12-0313] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Previous studies have shown that the DNA repair component Metnase (SETMAR) mediates resistance to DNA damaging cancer chemotherapy. Metnase has a nuclease domain that shares homology with the Transposase family. We therefore virtually screened the tertiary Metnase structure against the 550,000 compound ChemDiv library to identify small molecules that might dock in the active site of the transposase nuclease domain of Metnase. We identified eight compounds as possible Metnase inhibitors. Interestingly, among these candidate inhibitors were quinolone antibiotics and HIV integrase inhibitors, which share common structural features. Previous reports have described possible activity of quinolones as antineoplastic agents. Therefore, we chose the quinolone ciprofloxacin for further study, based on its wide clinical availability and low toxicity. We found that ciprofloxacin inhibits the ability of Metnase to cleave DNA and inhibits Metnase-dependent DNA repair. Ciprofloxacin on its own did not induce DNA damage, but it did reduce repair of chemotherapy-induced DNA damage. Ciprofloxacin increased the sensitivity of cancer cell lines and a xenograft tumor model to clinically relevant chemotherapy. These studies provide a mechanism for the previously postulated antineoplastic activity of quinolones, and suggest that ciprofloxacin might be a simple yet effective adjunct to cancer chemotherapy.
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Affiliation(s)
- Elizabeth A Williamson
- Department of Medicine, University of Florida and Shands Health Care System, Gainesville, Florida, USA
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31
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Hromas R, Williamson EA, Fnu S, Lee YJ, Park SJ, Beck BD, You JS, Leitao A, Laitao A, Nickoloff JA, Lee SH. Chk1 phosphorylation of Metnase enhances DNA repair but inhibits replication fork restart. Oncogene 2012; 31:4245-54. [PMID: 22231448 DOI: 10.1038/onc.2011.586] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Chk1 both arrests replication forks and enhances repair of DNA damage by phosphorylating downstream effectors. Although there has been a concerted effort to identify effectors of Chk1 activity, underlying mechanisms of effector action are still being identified. Metnase (also called SETMAR) is a SET and transposase domain protein that promotes both DNA double-strand break (DSB) repair and restart of stalled replication forks. In this study, we show that Metnase is phosphorylated only on Ser495 (S495) in vivo in response to DNA damage by ionizing radiation. Chk1 is the major mediator of this phosphorylation event. We had previously shown that wild-type (wt) Metnase associates with chromatin near DSBs and methylates histone H3 Lys36. Here we show that a Ser495Ala (S495A) Metnase mutant, which is not phosphorylated by Chk1, is defective in DSB-induced chromatin association. The S495A mutant also fails to enhance repair of an induced DSB when compared with wt Metnase. Interestingly, the S495A mutant demonstrated increased restart of stalled replication forks compared with wt Metnase. Thus, phosphorylation of Metnase S495 differentiates between these two functions, enhancing DSB repair and repressing replication fork restart. In summary, these data lend insight into the mechanism by which Chk1 enhances repair of DNA damage while at the same time repressing stalled replication fork restart.
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Affiliation(s)
- R Hromas
- Department of Medicine, University of Florida and Shands Health Care System, Gainesville, FL 32610, USA.
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Kines KJ, Belancio VP. Expressing genes do not forget their LINEs: transposable elements and gene expression. FRONT BIOSCI-LANDMRK 2012; 17:1329-44. [PMID: 22201807 DOI: 10.2741/3990] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Historically the accumulated mass of mammalian transposable elements (TEs), particularly those located within gene boundaries, was viewed as a genetic burden potentially detrimental to the genomic landscape. This notion has been strengthened by the discovery that transposable sequences can alter the architecture of the transcriptome, not only through insertion, but also long after the integration process is completed. Insertions previously considered harmless are now known to impact the expression of host genes via modification of the transcript quality or quantity, transcriptional interference, or by the control of pathways that affect the mRNA life-cycle. Conversely, several examples of the evolutionary advantageous impact of TEs on the host gene structure that diversified the cellular transcriptome are reported. TE-induced changes in gene expression can be tissue- or disease-specific, raising the possibility that the impact of TE sequences may vary during development, among normal cell types, and between normal and disease-affected tissues. The understanding of the rules and abundance of TE-interference with gene expression is in its infancy, and its contribution to human disease and/or evolution remains largely unexplored.
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Affiliation(s)
- Kristine J Kines
- Department of Structural and Cellular Biology, Tulane University School of Medicine, Tulane University Cancer Center and Tulane Center for Aging
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34
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Beck BD, Lee SS, Williamson E, Hromas RA, Lee SH. Biochemical characterization of metnase's endonuclease activity and its role in NHEJ repair. Biochemistry 2011; 50:4360-70. [PMID: 21491884 PMCID: PMC3388547 DOI: 10.1021/bi200333k] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Metnase (SETMAR) is a SET-transposase fusion protein that promotes nonhomologous end joining (NHEJ) repair in humans. Although both SET and the transposase domains were necessary for its function in DSB repair, it is not clear what specific role Metnase plays in the NHEJ. In this study, we show that Metnase possesses a unique endonuclease activity that preferentially acts on ssDNA and ssDNA-overhang of a partial duplex DNA. Cell extracts lacking Metnase poorly supported DNA end joining, and addition of wt-Metnase to cell extracts lacking Metnase markedly stimulated DNA end joining, while a mutant (D483A) lacking endonuclease activity did not. Given that Metnase overexpression enhanced DNA end processing in vitro, our finding suggests a role for Metnase's endonuclease activity in promoting the joining of noncompatible ends.
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Affiliation(s)
- Brian D. Beck
- Department of Biochemistry & Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA
| | - Sung-Sook Lee
- Department of Biochemistry & Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA
| | - Elizabeth Williamson
- Department of Medicine, University of Florida and Shands Health Care System, Gainesville, Florida 32610, USA
| | - Robert A. Hromas
- Department of Medicine, University of Florida and Shands Health Care System, Gainesville, Florida 32610, USA
| | - Suk-Hee Lee
- Department of Biochemistry & Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA
- Indiana University Simon Cancer Center, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA
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35
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Goodwin KD, He H, Imasaki T, Lee SH, Georgiadis MM. Crystal structure of the human Hsmar1-derived transposase domain in the DNA repair enzyme Metnase. Biochemistry 2010; 49:5705-13. [PMID: 20521842 DOI: 10.1021/bi100171x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Although the human genome is littered with sequences derived from the Hsmar1 transposon, the only intact Hsmar1 transposase gene exists within a chimeric SET-transposase fusion protein referred to as Metnase or SETMAR. Metnase retains many of the transposase activities including terminal inverted repeat (TIR) specific DNA-binding activity, DNA cleavage activity, albeit uncoupled from TIR-specific binding, and the ability to form a synaptic complex. However, Metnase has evolved as a DNA repair protein that is specifically involved in nonhomologous end joining. Here, we present two crystal structures of the transposase catalytic domain of Metnase revealing a dimeric enzyme with unusual active site plasticity that may be involved in modulating metal binding. We show through characterization of a dimerization mutant, F460K, that the dimeric form of the enzyme is required for its DNA cleavage, DNA-binding, and nonhomologous end joining activities. Of significance is the conservation of F460 along with residues that we propose may be involved in the modulation of metal binding in both the predicted ancestral Hsmar1 transposase sequence as well as in the modern enzyme. The Metnase transposase has been remarkably conserved through evolution; however, there is a clustering of substitutions located in alpha helices 4 and 5 within the putative DNA-binding site, consistent with loss of transposition specific DNA cleavage activity and acquisition of DNA repair specific cleavage activity.
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Affiliation(s)
- Kristie D Goodwin
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA
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36
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Hickman AB, Chandler M, Dyda F. Integrating prokaryotes and eukaryotes: DNA transposases in light of structure. Crit Rev Biochem Mol Biol 2010; 45:50-69. [PMID: 20067338 DOI: 10.3109/10409230903505596] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
DNA rearrangements are important in genome function and evolution. Genetic material can be rearranged inadvertently during processes such as DNA repair, or can be moved in a controlled manner by enzymes specifically dedicated to the task. DNA transposases comprise one class of such enzymes. These move DNA segments known as transposons to new locations, without the need for sequence homology between transposon and target site. Several biochemically distinct pathways have evolved for DNA transposition, and genetic and biochemical studies have provided valuable insights into many of these. However, structural information on transposases - particularly with DNA substrates - has proven elusive in most cases. On the other hand, large-scale genome sequencing projects have led to an explosion in the number of annotated prokaryotic and eukaryotic mobile elements. Here, we briefly review biochemical and mechanistic aspects of DNA transposition, and propose that integrating sequence information with structural information using bioinformatics tools such as secondary structure prediction and protein threading can lead not only to an additional level of understanding but possibly also to testable hypotheses regarding transposition mechanisms. Detailed understanding of transposition pathways is a prerequisite for the long-term goal of exploiting DNA transposons as genetic tools and as a basis for genetic medical applications.
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Affiliation(s)
- Alison Burgess Hickman
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, MD 20892, USA.
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Metnase/SETMAR: a domesticated primate transposase that enhances DNA repair, replication, and decatenation. Genetica 2010; 138:559-66. [PMID: 20309721 PMCID: PMC2847698 DOI: 10.1007/s10709-010-9452-1] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2009] [Accepted: 02/28/2010] [Indexed: 01/14/2023]
Abstract
Metnase is a fusion gene comprising a SET histone methyl transferase domain and a transposase domain derived from the Mariner transposase. This fusion gene appeared first in anthropoid primates. Because of its biochemical activities, both histone (protein) methylase and endonuclease, we termed the protein Metnase (also called SETMAR). Metnase methylates histone H3 lysine 36 (H3K36), improves the integration of foreign DNA, and enhances DNA double-strand break (DSB) repair by the non-homologous end joining (NHEJ) pathway, potentially dependent on its interaction with DNA Ligase IV. Metnase interacts with PCNA and enhances replication fork restart after stalling. Metnase also interacts with and stimulates TopoIIα-dependent chromosome decatenation and regulates cellular sensitivity to topoisomerase inhibitors used as cancer chemotherapeutics. Metnase has DNA nicking and endonuclease activity that linearizes but does not degrade supercoiled plasmids. Metnase has many but not all of the properties of a transposase, including Terminal Inverted Repeat (TIR) sequence-specific DNA binding, DNA looping, paired end complex formation, and cleavage of the 5′ end of a TIR, but it cannot efficiently complete transposition reactions. Interestingly, Metnase suppresses chromosomal translocations. It has been hypothesized that transposase activity would be deleterious in primates because unregulated DNA movement would predispose to malignancy. Metnase may have been selected for in primates because of its DNA repair and translocation suppression activities. Thus, its transposase activities may have been subverted to prevent deleterious DNA movement.
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38
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Atkinson H, Chalmers R. Delivering the goods: viral and non-viral gene therapy systems and the inherent limits on cargo DNA and internal sequences. Genetica 2010; 138:485-98. [PMID: 20084428 DOI: 10.1007/s10709-009-9434-3] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2009] [Accepted: 12/20/2009] [Indexed: 11/25/2022]
Abstract
Viruses have long been considered to be the most promising tools for human gene therapy. However, the initial enthusiasm for the use of viruses has been tarnished in the light of potentially fatal side effects. Transposons have a long history of use with bacteria in the laboratory and are now routinely applied to eukaryotic model organisms. Transposons show promise for applications in human genetic modification and should prove a useful addition to the gene therapy tool kit. Here we review the use of viruses and the limitations of current approaches to gene therapy, followed by a more detailed analysis of transposon length and the physical properties of internal sequences, which both affect transposition efficiency. As transposon length increases, transposition decreases: this phenomenon is known as length-dependence, and has implications for vector cargo capacity. Disruption of internal sequences, either via deletion of native DNA or insertion of exogenous DNA, may reduce or enhance genetic mobility. These effects may be related to host factor binding, essential spacer requirements or other influences yet to be elucidated. Length-dependence is a complex phenomenon driven not simply by the distance between the transposon ends, but by host proteins, the transposase and the properties of the DNA sequences encoded within the transposon.
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Affiliation(s)
- Helen Atkinson
- School of Biomedical Sciences, University of Nottingham, Queen's Medical Center, Nottingham NG7 2UH, UK
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39
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Claeys Bouuaert C, Chalmers R. Transposition of the human Hsmar1 transposon: rate-limiting steps and the importance of the flanking TA dinucleotide in second strand cleavage. Nucleic Acids Res 2009; 38:190-202. [PMID: 19858101 PMCID: PMC2800235 DOI: 10.1093/nar/gkp891] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Hsmar1 is a member of the mariner family of DNA transposons. Although widespread in nature, their molecular mechanism remains obscure. Many other cut-and-paste elements use a hairpin intermediate to cleave the two strands of DNA at each transposon end. However, this intermediate is absent in mariner, suggesting that these elements use a fundamentally different mechanism for second-strand cleavage. We have taken advantage of the faithful and efficient in vitro reaction provided by Hsmar1 to characterize the products and intermediates of transposition. We report different factors that particularly affect the reaction, which are the reaction pH and the transposase concentration. Kinetic analysis revealed that first-strand nicking and integration are rapid. The rate of the reaction is limited in part by the divalent metal ion-dependent assembly of a complex between transposase and the transposon end(s) prior to the first catalytic step. Second-strand cleavage is the rate-limiting catalytic step of the reaction. We discuss our data in light of a model for the two metal ion catalytic mechanism and propose that mariner excision involves a significant conformational change between first- and second-strand cleavage at each transposon end. Furthermore, this conformational change requires specific contacts between transposase and the flanking TA dinucleotide.
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40
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Lampe DJ. Bacterial genetic methods to explore the biology of mariner transposons. Genetica 2009; 138:499-508. [PMID: 19711186 DOI: 10.1007/s10709-009-9401-z] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2009] [Accepted: 08/10/2009] [Indexed: 10/20/2022]
Abstract
Mariners are small DNA mediated transposons of eukaryotes that fortuitously function in bacteria. Using bacterial genetics, it is possible to study a variety of properties of mariners, including transpositional ability, dominant-negative regulation, overexpresson inhibition, and the function of cis-acting sequences like the inverted terminal repeats. In conjunction with biochemical techniques, the structure of the transposase can be elucidated and the activity of the elements can be improved for genetic tool use. Finally, it is possible to uncover functional transposase genes directly from genomes given a suitable bacterial genetic screen.
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Affiliation(s)
- David J Lampe
- Department of Biological Sciences, Duquesne University, 600 Forbes Ave., Pittsburgh, PA 15116, USA.
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41
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Mariner transposons as genetic tools in vertebrate cells. Genetica 2009; 137:9-17. [PMID: 19479327 DOI: 10.1007/s10709-009-9370-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2008] [Accepted: 05/13/2009] [Indexed: 01/12/2023]
Abstract
Transposable elements (TEs) are being investigated as potential molecular tools in genetic engineering, for use in procedures such as transgenesis and insertional mutagenesis. Naturally active and reconstructed active TEs are both being studied to develop non-viral delivery vehicles. To date, the active elements being used include three Mariner-Like Elements (MLEs). We review below the studies that have investigated the ability of these MLEs to insert a transgene in vertebrate cells.
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42
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Bao W, Jurka MG, Kapitonov VV, Jurka J. New superfamilies of eukaryotic DNA transposons and their internal divisions. Mol Biol Evol 2009; 26:983-93. [PMID: 19174482 PMCID: PMC2727372 DOI: 10.1093/molbev/msp013] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/13/2009] [Indexed: 12/23/2022] Open
Abstract
Despite their enormous diversity and abundance, all currently known eukaryotic DNA transposons belong to only 15 superfamilies. Here, we report two new superfamilies of DNA transposons, named Sola and Zator. Sola transposons encode DDD-transposases (transposase, TPase) and are flanked by 4-bp target site duplications (TSD). Elements from the Sola superfamily are distributed in a variety of species including bacteria, protists, plants, and metazoans. They can be divided into three distinct groups of elements named Sola1, Sola2, and Sola3. The elements from each group have extremely low sequence identity to each other, different termini, and different target site preferences. However, all three groups belong to a single superfamily based on significant PSI-Blast identities between their TPases. The DDD TPase sequences encoded by Sola transposons are not similar to any known TPases. The second superfamily named Zator is characterized by 3-bp TSD. The Zator superfamily is relatively rare in eukaryotic species, and it evolved from a bacterial transposon encoding a TPase belonging to the "transposase 36" family (Pfam07592). These transposons are named TP36 elements (abbreviated from transposase 36).
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Affiliation(s)
- Weidong Bao
- Genetic Information Research Institute, Mountain View, CA, USA
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43
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Nowacki M, Higgins BP, Maquilan GM, Swart EC, Doak TG, Landweber LF. A functional role for transposases in a large eukaryotic genome. Science 2009; 324:935-8. [PMID: 19372392 DOI: 10.1126/science.1170023] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Despite comprising much of the eukaryotic genome, few transposons are active, and they usually confer no benefit to the host. Through an exaggerated process of genome rearrangement, Oxytricha trifallax destroys 95% of its germline genome during development. This includes the elimination of all transposon DNA. We show that germline-limited transposase genes play key roles in this process of genome-wide DNA excision, which suggests that transposases function in large eukaryotic genomes containing thousands of active transposons. We show that transposase gene expression occurs during germline-soma differentiation and that silencing of transposase by RNA interference leads to abnormal DNA rearrangement in the offspring. This study suggests a new important role in Oxytricha for this large portion of genomic DNA that was previously thought of as junk.
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Affiliation(s)
- Mariusz Nowacki
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ 08544, USA
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44
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Abstract
Transposable elements are mobile genetic units that exhibit broad diversity in their structure and transposition mechanisms. Transposable elements occupy a large fraction of many eukaryotic genomes and their movement and accumulation represent a major force shaping the genes and genomes of almost all organisms. This review focuses on DNA-mediated or class 2 transposons and emphasizes how this class of elements is distinguished from other types of mobile elements in terms of their structure, amplification dynamics, and genomic effect. We provide an up-to-date outlook on the diversity and taxonomic distribution of all major types of DNA transposons in eukaryotes, including Helitrons and Mavericks. We discuss some of the evolutionary forces that influence their maintenance and diversification in various genomic environments. Finally, we highlight how the distinctive biological features of DNA transposons have contributed to shape genome architecture and led to the emergence of genetic innovations in different eukaryotic lineages.
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Affiliation(s)
- Cédric Feschotte
- Department of Biology, University of Texas, Arlington, TX 76019, USA.
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45
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Beck BD, Park SJ, Lee YJ, Roman Y, Hromas RA, Lee SH. Human Pso4 is a metnase (SETMAR)-binding partner that regulates metnase function in DNA repair. J Biol Chem 2008; 283:9023-30. [PMID: 18263876 DOI: 10.1074/jbc.m800150200] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Metnase, also known as SETMAR, is a SET and transposase fusion protein with an undefined role in mammalian DNA repair. The SET domain is responsible for histone lysine methyltransferase activity at histone 3 K4 and K36, whereas the transposase domain possesses 5'-terminal inverted repeat (TIR)-specific DNA binding, DNA looping, and DNA cleavage activities. Although the transposase domain is essential for Metnase function in DNA repair, it is not clear how a protein with sequence-specific DNA binding activity plays a role in DNA repair. Here, we show that human homolog of the ScPSO4/PRP19 (hPso4) forms a stable complex with Metnase on both TIR and non-TIR DNA. The transposase domain essential for Metnase-TIR interaction is not sufficient for its interaction with non-TIR DNA in the presence of hPso4. In vivo, hPso4 is induced and co-localized with Metnase following ionizing radiation treatment. Cells treated with hPso4-siRNA failed to show Metnase localization at DSB sites and Metnase-mediated stimulation of DNA end joining coupled to genomic integration, suggesting that hPso4 is necessary to bring Metnase to the DSB sites for its function(s) in DNA repair.
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Affiliation(s)
- Brian D Beck
- Department of Biochemistry & Molecular Biology and the Walther Cancer Institute, Indiana University School of Medicine, 1044 W. Walnut Street, Indianapolis, IN 46202, USA
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46
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Abstract
Although alterations in the genomes of somatic cells cannot be passed on to future generations, they can have beneficial or detrimental effects on the host organism, depending on the context in which they occur. This review outlines the ways in which transposable elements have important consequences for somatic cell genomes.
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Affiliation(s)
- Lara S Collier
- The Department of Genetics, Cell Biology and Development, The Cancer Center, The University of Minnesota Twin Cities, Church St SE, Minneapolis, Minnesota 55455, USA.
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47
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Roman Y, Oshige M, Lee YJ, Goodwin K, Georgiadis MM, Hromas RA, Lee SH. Biochemical characterization of a SET and transposase fusion protein, Metnase: its DNA binding and DNA cleavage activity. Biochemistry 2007; 46:11369-76. [PMID: 17877369 PMCID: PMC3374406 DOI: 10.1021/bi7005477] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Metnase (SETMAR) is a SET and transposase fusion protein that promotes in vivo end joining activity and mediates genomic integration of foreign DNA. Recent studies showed that Metnase retained most of the transposase activities, including 5'-terminal inverted repeat (TIR)-specific binding and assembly of a paired end complex, and cleavage of the 5'-end of the TIR element. Here we show that R432 within the helix-turn-helix motif is critical for sequence-specific recognition, as the R432A mutation abolishes its TIR-specific DNA binding activity. Metnase possesses a unique DNA nicking and/or endonuclease activity that mediates cleavage of duplex DNA in the absence of the TIR sequence. While the HTH motif is essential for the Metnase-TIR interaction, it is not required for its DNA cleavage activity. The DDE-like motif is crucial for its DNA cleavage action as a point mutation at this motif (D483A) abolished its DNA cleavage activity. Together, our results suggest that Metnase's DNA cleavage activity, unlike those of other eukaryotic transposases, is not coupled to its sequence-specific DNA binding.
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Affiliation(s)
- Yaritzabel Roman
- Department of Biochemistry & Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA
- Walther Cancer Institute, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA
| | - Masahiko Oshige
- Department of Biochemistry & Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA
- Walther Cancer Institute, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA
| | - Young-Ju Lee
- Department of Biochemistry & Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA
- Walther Cancer Institute, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA
| | - Kristie Goodwin
- Department of Biochemistry & Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA
| | - Millie M. Georgiadis
- Department of Biochemistry & Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA
| | - Robert A. Hromas
- Department of Internal Medicine and the Cancer Treatment and Research Center, the University of New Mexico, Albuquerque, New Mexico 87131, USA
| | - Suk-Hee Lee
- Department of Biochemistry & Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA
- Walther Cancer Institute, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA
- Corresponding author: Suk-Hee Lee, IU Cancer Research Institute (Rm153), 1044 W. Walnut St., Indianapolis, Indiana 46202. Phone: +1-317-278-3464, Fax: +1-317-274-8046;
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48
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Richardson JM, Finnegan DJ, Walkinshaw MD. Crystallization of a Mos1 transposase-inverted-repeat DNA complex: biochemical and preliminary crystallographic analyses. Acta Crystallogr Sect F Struct Biol Cryst Commun 2007; 63:434-7. [PMID: 17565190 PMCID: PMC2335011 DOI: 10.1107/s1744309107019045] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2007] [Accepted: 04/17/2007] [Indexed: 11/10/2022]
Abstract
A complex formed between Mos1 transposase and its inverted-repeat DNA has been crystallized. The crystals diffract to 3.25 A resolution and exhibit monoclinic (P2(1)) symmetry, with unit-cell parameters a = 120.8, b = 85.1, c = 131.6 A, beta = 99.3 degrees . The X-ray diffraction data display noncrystallographic twofold symmetry and characteristic dsDNA diffraction at approximately 3.3 A. Biochemical analyses confirmed the presence of DNA and full-length protein in the crystals. The relationship between the axis of noncrystallographic symmetry, the unit-cell axes and the DNA diffraction pattern are discussed. The data are consistent with the previously proposed model of the paired-ends complex containing a dimer of the transposase.
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Affiliation(s)
- Julia M Richardson
- School of Biological Sciences, University of Edinburgh, The King's Buildings, Mayfield Road, Edinburgh EH9 3JR, Scotland.
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49
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Miskey C, Papp B, Mátés L, Sinzelle L, Keller H, Izsvák Z, Ivics Z. The ancient mariner sails again: transposition of the human Hsmar1 element by a reconstructed transposase and activities of the SETMAR protein on transposon ends. Mol Cell Biol 2007; 27:4589-600. [PMID: 17403897 PMCID: PMC1900042 DOI: 10.1128/mcb.02027-06] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Hsmar1, one of the two subfamilies of mariner transposons in humans, is an ancient element that entered the primate genome lineage approximately 50 million years ago. Although Hsmar1 elements are inactive due to mutational damage, one particular copy of the transposase gene has apparently been under selection. This transposase coding region is part of the SETMAR gene, in which a histone methylatransferase SET domain is fused to an Hsmar1 transposase domain. A phylogenetic approach was taken to reconstruct the ancestral Hsmar1 transposase gene, which we named Hsmar1-Ra. The Hsmar1-Ra transposase efficiently mobilizes Hsmar1 transposons by a cut-and-paste mechanism in human cells and zebra fish embryos. Hsmar1-Ra can also mobilize short inverted-repeat transposable elements (MITEs) related to Hsmar1 (MiHsmar1), thereby establishing a functional relationship between an Hsmar1 transposase source and these MITEs. MiHsmar1 excision is 2 orders of magnitude more efficient than that of long elements, thus providing an explanation for their high copy numbers. We show that the SETMAR protein binds and introduces single-strand nicks into Hsmar1 inverted-repeat sequences in vitro. Pathway choices for DNA break repair were found to be characteristically different in response to transposon cleavage mediated by Hsmar1-Ra and SETMAR in vivo. Whereas nonhomologous end joining plays a dominant role in repairing excision sites generated by the Hsmar1-Ra transposase, DNA repair following cleavage by SETMAR predominantly follows a homology-dependent pathway. The novel transposon system can be a useful tool for genome manipulations in vertebrates and for investigations into the transpositional dynamics and the contributions of these elements to primate genome evolution.
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Affiliation(s)
- Csaba Miskey
- Max Delbrück Center for Molecular Medicine, Robert Rössle Str 10, Berlin, Germany
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50
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Petit A, Rouleux-Bonnin F, Lambelé M, Pollet N, Bigot Y. Properties of the various Botmar1 transcripts in imagoes of the bumble bee, Bombus terrestris (Hymenoptera: Apidae). Gene 2007; 390:52-66. [PMID: 17088026 DOI: 10.1016/j.gene.2006.07.025] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2006] [Revised: 07/17/2006] [Accepted: 07/18/2006] [Indexed: 11/24/2022]
Abstract
Botmar1 elements are mariner-like elements (MLEs), class II transposable elements that occur in the genome of the bumble bee, Bombus terrestris. Each haploid B. terrestris genome contains about 230 Botmar1, consisting entirely of 1.3-kb and 0.85-kb elements. During their evolution in the B. terrestris genome, two Botmar1 lineages have been differentiated in terms of their nucleic acid sequences and the differences found in their 5' untranslated regions suggest that they could be transcribed differently in B. terrestris. Here, we show that small amounts of Botmar1 mRNA occur in RNA extracts purified from B. terrestris imagoes. This indicates that the Botmar1 transcription is either weak in imagoes, or is restricted to very few cells. The cloning of several mRNAs reveals that only lineage-2 Botmar1 elements are transcribed. This transcription is specific, and uses cardinal initiators and terminators of eukaryotic elements in the Botmar1 elements. The intrastrand stem-loop folds in the mRNA theoretically synthesized by elements of the first lineage suggest that mRNA maintenance in cells might be self-regulated by RNA interference.
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Affiliation(s)
- Agnès Petit
- Laboratoire d'Etude des Parasites Génétiques, FRE-CNRS 2969, Université François Rabelais, UFR des Sciences et Techniques, Bâtiment L, Parc de Grandmont, 37200 Tours, France
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