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Lu Y, Rice E, Du K, Kneitz S, Naville M, Dechaud C, Volff JN, Boswell M, Boswell W, Hillier L, Tomlinson C, Milin K, Walter RB, Schartl M, Warren WC. High resolution genomes of multiple Xiphophorus species provide new insights into microevolution, hybrid incompatibility, and epistasis. Genome Res 2023; 33:557-571. [PMID: 37147111 PMCID: PMC10234306 DOI: 10.1101/gr.277434.122] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Accepted: 03/29/2023] [Indexed: 05/07/2023]
Abstract
Because of diverged adaptative phenotypes, fish species of the genus Xiphophorus have contributed to a wide range of research for a century. Existing Xiphophorus genome assemblies are not at the chromosomal level and are prone to sequence gaps, thus hindering advancement of the intra- and inter-species differences for evolutionary, comparative, and translational biomedical studies. Herein, we assembled high-quality chromosome-level genome assemblies for three distantly related Xiphophorus species, namely, X. maculatus, X. couchianus, and X. hellerii Our overall goal is to precisely assess microevolutionary processes in the clade to ascertain molecular events that led to the divergence of the Xiphophorus species and to progress understanding of genetic incompatibility to disease. In particular, we measured intra- and inter-species divergence and assessed gene expression dysregulation in reciprocal interspecies hybrids among the three species. We found expanded gene families and positively selected genes associated with live bearing, a special mode of reproduction. We also found positively selected gene families are significantly enriched in nonpolymorphic transposable elements, suggesting the dispersal of these nonpolymorphic transposable elements has accompanied the evolution of the genes, possibly by incorporating new regulatory elements in support of the Britten-Davidson hypothesis. We characterized inter-specific polymorphisms, structural variants, and polymorphic transposable element insertions and assessed their association to interspecies hybridization-induced gene expression dysregulation related to specific disease states in humans.
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Affiliation(s)
- Yuan Lu
- The Xiphophorus Genetic Stock Center, Texas State University, San Marcos, Texas 78666, USA;
| | - Edward Rice
- Department of Animal Sciences, Department of Surgery, Institute for Data Science and Informatics, University of Missouri, Bond Life Sciences Center, Columbia, Missouri 65201, USA
| | - Kang Du
- The Xiphophorus Genetic Stock Center, Texas State University, San Marcos, Texas 78666, USA
| | - Susanne Kneitz
- Biochemistry and Cell Biology, Biozentrum, University of Würzburg, 97074 Würzburg, Germany
| | - Magali Naville
- Institut de Génomique Fonctionnelle de Lyon, Ecole Normale Supérieure de Lyon, CNRS UMR 5242, Université Claude Bernard Lyon 1, F-69364 Lyon, France
| | - Corentin Dechaud
- Institut de Génomique Fonctionnelle de Lyon, Ecole Normale Supérieure de Lyon, CNRS UMR 5242, Université Claude Bernard Lyon 1, F-69364 Lyon, France
| | - Jean-Nicolas Volff
- Institut de Génomique Fonctionnelle de Lyon, Ecole Normale Supérieure de Lyon, CNRS UMR 5242, Université Claude Bernard Lyon 1, F-69364 Lyon, France
| | - Mikki Boswell
- The Xiphophorus Genetic Stock Center, Texas State University, San Marcos, Texas 78666, USA
| | - William Boswell
- The Xiphophorus Genetic Stock Center, Texas State University, San Marcos, Texas 78666, USA
| | - LaDeana Hillier
- Department of Genome Sciences, University of Washington, Seattle, Washington 98195, USA
| | - Chad Tomlinson
- McDonnell Genome Institute, Washington University, St. Louis, Missouri 63108, USA
| | - Kremitzki Milin
- McDonnell Genome Institute, Washington University, St. Louis, Missouri 63108, USA
| | - Ronald B Walter
- Department of Life Sciences, Texas A&M University, Corpus Christi, Texas 78412, USA
| | - Manfred Schartl
- The Xiphophorus Genetic Stock Center, Texas State University, San Marcos, Texas 78666, USA
- Developmental Biochemistry, Biozentrum, University of Würzburg, 97074 Würzburg, Germany
| | - Wesley C Warren
- Department of Animal Sciences, Department of Surgery, Institute for Data Science and Informatics, University of Missouri, Bond Life Sciences Center, Columbia, Missouri 65201, USA
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2
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Spadafora C. The epigenetic basis of evolution. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2023; 178:57-69. [PMID: 36720315 DOI: 10.1016/j.pbiomolbio.2023.01.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Revised: 12/17/2022] [Accepted: 01/26/2023] [Indexed: 01/31/2023]
Abstract
An increasing body of data are revealing key roles of epigenetics in evolutionary processes. The scope of this manuscript is to assemble in a coherent frame experimental evidence supporting a role of epigenetic factors and networks, active during embryogenesis, in orchestrating variation-inducing phenomena underlying evolution, seen as a global process. This process unfolds over two crucial levels: i) a flow of RNA-based information - predominantly small regulatory RNAs released from somatic cells exposed to environmental stimuli - taken up by spermatozoa and delivered to oocytes at fertilization and ii) the highly permissive and variation-prone environments offered by zygotes and totipotent early embryos. Totipotent embryos provide a variety of biological tools favouring the emergence of evolutionarily significant phenotypic novelties driven by RNA information. Under this light, neither random genomic mutations, nor the sieving role of natural selection are required, as the sperm-delivered RNA cargo conveys specific information and acts as "phenotypic-inducer" of defined environmentally acquired traits.
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Affiliation(s)
- Corrado Spadafora
- Institute of Translational Pharmacology, National Research Council (CNR), Rome, Italy.
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3
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Paulat NS, McGuire E, Subramanian K, Osmanski AB, Moreno-Santillán DD, Ray DA, Xing J. Transposable Elements in Bats Show Differential Accumulation Patterns Determined by Class and Functionality. LIFE (BASEL, SWITZERLAND) 2022; 12:life12081190. [PMID: 36013369 PMCID: PMC9409754 DOI: 10.3390/life12081190] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Revised: 08/01/2022] [Accepted: 08/02/2022] [Indexed: 11/16/2022]
Abstract
Bat genomes are characterized by a diverse transposable element (TE) repertoire. In particular, the genomes of members of the family Vespertilionidae contain both active retrotransposons and active DNA transposons. Each TE type is characterized by a distinct pattern of accumulation over the past ~40 million years. Each also exhibits its own target site preferences (sometimes shared with other TEs) that impact where they are likely to insert when mobilizing. Therefore, bats provide a great resource for understanding the diversity of TE insertion patterns. To gain insight into how these diverse TEs impact genome structure, we performed comparative spatial analyses between different TE classes and genomic features, including genic regions and CpG islands. Our results showed a depletion of all TEs in the coding sequence and revealed patterns of species- and element-specific attraction in the transcript. Trends of attraction in the distance tests also suggested significant TE activity in regions adjacent to genes. In particular, the enrichment of small, non-autonomous TE insertions in introns and near coding regions supports the hypothesis that the genomic distribution of TEs is the product of a balance of the TE insertion preference in open chromatin regions and the purifying selection against TEs within genes.
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Affiliation(s)
- Nicole S. Paulat
- Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409, USA
| | - Erin McGuire
- Department of Genetics, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
| | - Krishnamurthy Subramanian
- Department of Genetics, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
- Human Genetics Institute of New Jersey, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
| | - Austin B. Osmanski
- Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409, USA
| | | | - David A. Ray
- Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409, USA
- Correspondence: (D.A.R.); (J.X.)
| | - Jinchuan Xing
- Department of Genetics, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
- Human Genetics Institute of New Jersey, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
- Correspondence: (D.A.R.); (J.X.)
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4
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Jeon YJ, Shin YH, Cheon SJ, Park YD. Identification and Characterization of PTE-2, a Stowaway-like MITE Activated in Transgenic Chinese Cabbage Lines. Genes (Basel) 2022; 13:genes13071222. [PMID: 35886005 PMCID: PMC9319602 DOI: 10.3390/genes13071222] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2022] [Revised: 07/07/2022] [Accepted: 07/07/2022] [Indexed: 02/01/2023] Open
Abstract
Transposable elements (TEs) are DNA fragments that can be replicated or transposed within a genome. TEs make up a high proportion of the plant genome and contribute to genetic diversity and evolution, affecting genome structure or gene activity. Miniature inverted-repeat transposable elements (MITEs) are short, non-autonomous class II DNA transposable elements. MITEs have specific sequences, target site duplications(TSDs), and terminal inverted repeats(TIRs), which are characteristics of the classification of MITE families. In this study, a Stowaway-like MITE, PTE-2, was activated in transgenic Chinese cabbage lines. PTE-2 was revealed by in silico analysis as the putative activated element in transgenic Chinese cabbage lines. To verify the in silico analysis data, MITE insertion polymorphism (MIP) PCR was conducted and PTE-2 was confirmed to be activated in transgenic Chinese cabbage lines. The activation tendency of the copy elements of PTE-2 at different loci was also analyzed and only one more element was activated in the transgenic Chinese cabbage lines. Analyzing the sequence of MIP PCR products, the TSD sequence and TIR motif of PTE-2 were identified and matched to the characteristics of the Stowaway-like MITE family. In addition, the flanking region of PTE-2 was modified when PTE-2 was activated.
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Affiliation(s)
| | | | | | - Young-Doo Park
- Correspondence: ; Tel.: +82-10-3338-9344; Fax: +82-31-202-8395
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5
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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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6
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Palmada-Flores M, Orkin JD, Haase B, Mountcastle J, Bertelsen MF, Fedrigo O, Kuderna LFK, Jarvis ED, Marques-Bonet T. A high-quality, long-read genome assembly of the endangered ring-tailed lemur (Lemur catta). Gigascience 2022; 11:6562532. [PMID: 35365833 PMCID: PMC8975718 DOI: 10.1093/gigascience/giac026] [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: 10/18/2021] [Revised: 01/14/2022] [Accepted: 02/19/2022] [Indexed: 01/31/2023] Open
Abstract
BACKGROUND The ring-tailed lemur (Lemur catta) is a charismatic strepsirrhine primate endemic to Madagascar. These lemurs are of particular interest, given their status as a flagship species and widespread publicity in the popular media. Unfortunately, a recent population decline has resulted in the census population decreasing to <2,500 individuals in the wild, and the species's classification as an endangered species by the IUCN. As is the case for most strepsirrhine primates, only a limited amount of genomic research has been conducted on L. catta, in part owing to the lack of genomic resources. RESULTS We generated a new high-quality reference genome assembly for L. catta (mLemCat1) that conforms to the standards of the Vertebrate Genomes Project. This new long-read assembly is composed of Pacific Biosciences continuous long reads (CLR data), Optical Mapping Bionano reads, Arima HiC data, and 10X linked reads. The contiguity and completeness of the assembly are extremely high, with scaffold and contig N50 values of 90.982 and 10.570 Mb, respectively. Additionally, when compared to other high-quality primate assemblies, L. catta has the lowest reported number of Alu elements, which results predominantly from a lack of AluS and AluY elements. CONCLUSIONS mLemCat1 is an excellent genomic resource not only for the ring-tailed lemur community, but also for other members of the Lemuridae family, and is the first very long read assembly for a strepsirrhine.
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Affiliation(s)
- Marc Palmada-Flores
- Department of Medicine and Life Sciences (MELIS), Institut de Biologia Evolutiva, Universitat Pompeu Fabra-CSIC, Barcelona 08003, Spain
| | - Joseph D Orkin
- Department of Medicine and Life Sciences (MELIS), Institut de Biologia Evolutiva, Universitat Pompeu Fabra-CSIC, Barcelona 08003, Spain.,Département d'anthropologie, Université de Montréal, Montréal, QC H3T 1N8, Canada
| | - Bettina Haase
- The Vertebrate Genomes Lab, The Rockefeller University, New York, NY 10065, USA
| | | | - Mads F Bertelsen
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg C 1870, Denmark.,Center for Zoo and Wild Animal Health, Copenhagen Zoo, Frederiksber 1870, Denmark
| | - Olivier Fedrigo
- The Vertebrate Genomes Lab, The Rockefeller University, New York, NY 10065, USA
| | - Lukas F K Kuderna
- Department of Medicine and Life Sciences (MELIS), Institut de Biologia Evolutiva, Universitat Pompeu Fabra-CSIC, Barcelona 08003, Spain
| | - Erich D Jarvis
- The Vertebrate Genomes Lab, The Rockefeller University, New York, NY 10065, USA.,Center for Zoo and Wild Animal Health, Copenhagen Zoo, Frederiksber 1870, Denmark.,Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA.,Laboratory of Neurogenetics of Language, The Rockefeller University, NY 10065, USA
| | - Tomas Marques-Bonet
- Department of Medicine and Life Sciences (MELIS), Institut de Biologia Evolutiva, Universitat Pompeu Fabra-CSIC, Barcelona 08003, Spain.,Catalan Institution of Research and Advanced Studies (ICREA), Barcelona 08010, Spain.,CNAG-CRG, Centre for Genomic Regulation (CRG), Barcelona Institute of Science and Technology (BIST), Barcelon 08028a, Spain.,Institut Català de Paleontologia Miquel Crusafont, Universitat Autònoma de Barcelona, Cerdanyola del Vallès 08193, Spain
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7
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Riba A, Fumagalli MR, Caselle M, Osella M. A Model-Driven Quantitative Analysis of Retrotransposon Distributions in the Human Genome. Genome Biol Evol 2021; 12:2045-2059. [PMID: 32986810 PMCID: PMC7750997 DOI: 10.1093/gbe/evaa201] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/19/2020] [Indexed: 12/21/2022] Open
Abstract
Retrotransposons, DNA sequences capable of creating copies of themselves, compose about half of the human genome and played a central role in the evolution of mammals. Their current position in the host genome is the result of the retrotranscription process and of the following host genome evolution. We apply a model from statistical physics to show that the genomic distribution of the two most populated classes of retrotransposons in human deviates from random placement, and that this deviation increases with time. The time dependence suggests a major role of the host genome dynamics in shaping the current retrotransposon distributions. Focusing on a neutral scenario, we show that a simple model based on random placement followed by genome expansion and sequence duplications can reproduce the empirical retrotransposon distributions, even though more complex and possibly selective mechanisms can have contributed. Besides the inherent interest in understanding the origin of current retrotransposon distributions, this work sets a general analytical framework to analyze quantitatively the effects of genome evolutionary dynamics on the distribution of genomic elements.
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Affiliation(s)
| | - Maria Rita Fumagalli
- Institute of Biophysics - CNR, National Research Council, Genova, Italy.,Department of Environmental Science and Policy, Center for Complexity and Biosystems, University of Milan, Milano, Italy
| | - Michele Caselle
- Department of Physics and INFN, University of Torino, Torino, Italy
| | - Matteo Osella
- Department of Physics and INFN, University of Torino, Torino, Italy
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8
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Miller WB, Enguita FJ, Leitão AL. Non-Random Genome Editing and Natural Cellular Engineering in Cognition-Based Evolution. Cells 2021; 10:1125. [PMID: 34066959 PMCID: PMC8148535 DOI: 10.3390/cells10051125] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2021] [Revised: 04/27/2021] [Accepted: 05/05/2021] [Indexed: 12/16/2022] Open
Abstract
Neo-Darwinism presumes that biological variation is a product of random genetic replication errors and natural selection. Cognition-Based Evolution (CBE) asserts a comprehensive alternative approach to phenotypic variation and the generation of biological novelty. In CBE, evolutionary variation is the product of natural cellular engineering that permits purposive genetic adjustments as cellular problem-solving. CBE upholds that the cornerstone of biology is the intelligent measuring cell. Since all biological information that is available to cells is ambiguous, multicellularity arises from the cellular requirement to maximize the validity of available environmental information. This is best accomplished through collective measurement purposed towards maintaining and optimizing individual cellular states of homeorhesis as dynamic flux that sustains cellular equipoise. The collective action of the multicellular measurement and assessment of information and its collaborative communication is natural cellular engineering. Its yield is linked cellular ecologies and mutualized niche constructions that comprise biofilms and holobionts. In this context, biological variation is the product of collective differential assessment of ambiguous environmental cues by networking intelligent cells. Such concerted action is enabled by non-random natural genomic editing in response to epigenetic impacts and environmental stresses. Random genetic activity can be either constrained or deployed as a 'harnessing of stochasticity'. Therefore, genes are cellular tools. Selection filters cellular solutions to environmental stresses to assure continuous cellular-organismal-environmental complementarity. Since all multicellular eukaryotes are holobionts as vast assemblages of participants of each of the three cellular domains (Prokaryota, Archaea, Eukaryota) and the virome, multicellular variation is necessarily a product of co-engineering among them.
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Affiliation(s)
| | - Francisco J. Enguita
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Av. Prof. Egas Moniz, 1649-028 Lisboa, Portugal;
| | - Ana Lúcia Leitão
- MEtRICs, Department of Sciences and Technology of Biomass, NOVA School of Science and Technology, FCT NOVA, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal;
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9
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Existence of Bov-B LINE Retrotransposons in Snake Lineages Reveals Recent Multiple Horizontal Gene Transfers with Copy Number Variation. Genes (Basel) 2020; 11:genes11111241. [PMID: 33105659 PMCID: PMC7716205 DOI: 10.3390/genes11111241] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 10/10/2020] [Accepted: 10/20/2020] [Indexed: 01/09/2023] Open
Abstract
Transposable elements (TEs) are dynamic elements present in all eukaryotic genomes. They can “jump” and amplify within the genome and promote segmental genome rearrangements on both autosomes and sex chromosomes by disruption of gene structures. The Bovine-B long interspersed nuclear element (Bov-B LINE) is among the most abundant TE-retrotransposon families in vertebrates due to horizontal transfer (HT) among vertebrate lineages. Recent studies have shown multiple HTs or the presence of diverse Bov-B LINE groups in the snake lineage. It is hypothesized that Bov-B LINEs are highly dynamic and that the diversity reflects multiple HTs in snake lineages. Partial sequences of Bov-B LINE from 23 snake species were characterized. Phylogenetic analysis resolved at least two Bov-B LINE groups that might correspond to henophidian and caenophidian snakes; however, the tree topology differed from that based on functional nuclear and mitochondrial gene sequences. Several Bov-B LINEs of snakes showed greater than 80% similarity to sequences obtained from insects, whereas the two Bov-B LINE groups as well as sequences from the same snake species classified in different Bov-B LINE groups showed sequence similarities of less than 80%. Calculation of estimated divergence time and pairwise divergence between all individual Bov-B LINE copies suggest invasion times ranging from 79.19 to 98.8 million years ago in snakes. Accumulation of elements in a lineage-specific fashion ranged from 9 × 10−6% to 5.63 × 10−2% per genome. The genomic proportion of Bov-B LINEs varied among snake species but was not directly associated with genome size or invasion time. No differentiation in Bov-B LINE copy number between males and females was observed in any of the snake species examined. Incongruence in tree topology between Bov-B LINEs and other snake phylogenies may reflect past HT events. Sequence divergence of Bov-B LINEs between copies suggests that recent multiple HTs occurred within the same evolutionary timeframe in the snake lineage. The proportion of Bov-B LINEs varies among species, reflecting species specificity in TE invasion. The rapid speciation of snakes, coinciding with Bov-B LINE invasion in snake genomes, leads us to better understand the effect of Bov-B LINEs on snake genome evolution.
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10
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Carducci F, Barucca M, Canapa A, Carotti E, Biscotti MA. Mobile Elements in Ray-Finned Fish Genomes. Life (Basel) 2020; 10:E221. [PMID: 32992841 PMCID: PMC7599744 DOI: 10.3390/life10100221] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 09/18/2020] [Accepted: 09/22/2020] [Indexed: 12/12/2022] Open
Abstract
Ray-finned fishes (Actinopterygii) are a very diverse group of vertebrates, encompassing species adapted to live in freshwater and marine environments, from the deep sea to high mountain streams. Genome sequencing offers a genetic resource for investigating the molecular bases of this phenotypic diversity and these adaptations to various habitats. The wide range of genome sizes observed in fishes is due to the role of transposable elements (TEs), which are powerful drivers of species diversity. Analyses performed to date provide evidence that class II DNA transposons are the most abundant component in most fish genomes and that compared to other vertebrate genomes, many TE superfamilies are present in actinopterygians. Moreover, specific TEs have been reported in ray-finned fishes as a possible result of an intricate relationship between TE evolution and the environment. The data summarized here underline the biological interest in Actinopterygii as a model group to investigate the mechanisms responsible for the high biodiversity observed in this taxon.
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Affiliation(s)
| | | | | | | | - Maria Assunta Biscotti
- Dipartimento di Scienze della Vita e dell’Ambiente, Università Politecnica delle Marche, 60131 Ancona, Italy; (F.C.); (M.B.); (A.C.); (E.C.)
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11
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Ghosh A, Platt RN, Vandewege MW, Tabassum R, Hsu CY, Isberg SR, Peterson DG, Finger JW, Kieran TJ, Glenn TC, Gongora J, Ray DA. Identification and characterization of microRNAs (miRNAs) and their transposable element origins in the saltwater crocodile, Crocodylus porosus. Anal Biochem 2020; 602:113781. [PMID: 32485163 DOI: 10.1016/j.ab.2020.113781] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Revised: 05/11/2020] [Accepted: 05/19/2020] [Indexed: 12/23/2022]
Abstract
MicroRNAs (miRNAs) are 18-24 nucleotide regulatory RNAs. They are involved in the regulation of genetic and biological pathways through post transcriptional gene silencing and/or translational repression. Data suggests a slow evolutionary rate for the saltwater crocodile (Crocodylus porosus) over the past several million years when compared to birds, the closest extant relatives of crocodilians. Understanding gene regulation in the saltwater crocodile in the context of relatively slow genomic change thus holds potential for the investigation of genomics, evolution, and adaptation. Utilizing eleven tissue types and sixteen small RNA libraries, we report 644 miRNAs in the saltwater crocodile with >78% of miRNAs being novel to crocodilians. We also identified potential targets for the miRNAs and analyzed the relationship of the miRNA repertoire to transposable elements (TEs). Results suggest an increased association of DNA transposons with miRNAs when compared to retrotransposons. This work reports the first comprehensive analysis of miRNAs in Crocodylus porosus and addresses the potential impacts of miRNAs in regulating the genome in the saltwater crocodile. In addition, the data suggests a supporting role of TEs as a source for miRNAs, adding to the increasing evidence that TEs play a significant role in the evolution of gene regulation.
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Affiliation(s)
- Arnab Ghosh
- Department of Biological Sciences, Texas Tech University, Lubbock, TX, USA
| | - Roy N Platt
- Department of Biological Sciences, Texas Tech University, Lubbock, TX, USA
| | - Michael W Vandewege
- Department of Biological Sciences, Texas Tech University, Lubbock, TX, USA; Department of Biology, Eastern New Mexico University, Portales, NM, USA
| | | | - Chuan-Yu Hsu
- Institute for Genomics, Biocomputing and Biotechnology, Mississippi State University, MS, USA
| | - Sally R Isberg
- Sydney School of Veterinary Science, Faculty of Science, University of Sydney, Sydney, NSW, Australia; The Centre for Crocodile Research, Darwin, NT, Australia
| | - Daniel G Peterson
- Institute for Genomics, Biocomputing and Biotechnology, Mississippi State University, MS, USA
| | - John W Finger
- Department of Environmental Health Science, University of Georgia, Athens, GA, USA; Department of Biological Sciences, Auburn University, Auburn, AL, USA
| | - Troy J Kieran
- Department of Environmental Health Science, University of Georgia, Athens, GA, USA
| | - Travis C Glenn
- Department of Environmental Health Science, University of Georgia, Athens, GA, USA
| | - Jaime Gongora
- Sydney School of Veterinary Science, Faculty of Science, University of Sydney, Sydney, NSW, Australia
| | - David A Ray
- Department of Biological Sciences, Texas Tech University, Lubbock, TX, USA.
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12
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Casanova EL, Konkel MK. The Developmental Gene Hypothesis for Punctuated Equilibrium: Combined Roles of Developmental Regulatory Genes and Transposable Elements. Bioessays 2020; 42:e1900173. [PMID: 31943266 DOI: 10.1002/bies.201900173] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Revised: 11/30/2019] [Indexed: 12/13/2022]
Abstract
Theories of the genetics underlying punctuated equilibrium (PE) have been vague to date. Here the developmental gene hypothesis is proposed, which states that: 1) developmental regulatory (DevReg) genes are responsible for the orchestration of metazoan morphogenesis and their extreme conservation and mutation intolerance generates the equilibrium or stasis present throughout much of the fossil record and 2) the accumulation of regulatory elements and recombination within these same genes-often derived from transposable elements-drives punctuated bursts of morphological divergence and speciation across metazoa. This two-part hypothesis helps to explain the features that characterize PE, providing a theoretical genetic basis for the once-controversial theory. Also see the video abstract here https://youtu.be/C-fu-ks5yDs.
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Affiliation(s)
- Emily L Casanova
- Department of Biomedical Sciences, University of South Carolina School of Medicine at Greenville, 200A Patewood Dr., Greenville, SC, 29615, USA
| | - Miriam K Konkel
- Department of Genetics, Clemson Center for Human Genetics, Biomedical Data Science and Informatics Program, Clemson University, 105 Collings St., Clemson, SC, 29631, USA
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Tang W, Liang P. Comparative Genomics Analysis Reveals High Levels of Differential Retrotransposition among Primates from the Hominidae and the Cercopithecidae Families. Genome Biol Evol 2019; 11:3309-3325. [PMID: 31651947 PMCID: PMC6934888 DOI: 10.1093/gbe/evz234] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/24/2019] [Indexed: 12/11/2022] Open
Abstract
Mobile elements (MEs), making ∼50% of primate genomes, are known to be responsible for generating inter- and intra-species genomic variations and play important roles in genome evolution and gene function. Using a bioinformatics comparative genomics approach, we performed analyses of species-specific MEs (SS-MEs) in eight primate genomes from the families of Hominidae and Cercopithecidae, focusing on retrotransposons. We identified a total of 230,855 SS-MEs, with which we performed normalization based on evolutionary distances, and we also analyzed the most recent SS-MEs in these genomes. Comparative analysis of SS-MEs reveals striking differences in ME transposition among these primate genomes. Interesting highlights of our results include: 1) the baboon genome has the highest number of SS-MEs with a strong bias for SINEs, while the crab-eating macaque genome has a sustained extremely low transposition for all ME classes, suggesting the existence of a genome-wide mechanism suppressing ME transposition; 2) while SS-SINEs represent the dominant class in general, the orangutan genome stands out by having SS-LINEs as the dominant class; 3) the human genome stands out among the eight genomes by having the largest number of recent highly active ME subfamilies, suggesting a greater impact of ME transposition on its recent evolution; and 4) at least 33% of the SS-MEs locate to genic regions, including protein coding regions, presenting significant potentials for impacting gene function. Our study, as the first of its kind, demonstrates that mobile elements evolve quite differently among these primates, suggesting differential ME transposition as an important mechanism in primate evolution.
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Affiliation(s)
| | - Ping Liang
- Department of Biological Sciences, Brock University, St. Catharines, Ontario, Canada
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Evolution and diversity of transposable elements in fish genomes. Sci Rep 2019; 9:15399. [PMID: 31659260 PMCID: PMC6817897 DOI: 10.1038/s41598-019-51888-1] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Accepted: 10/09/2019] [Indexed: 12/22/2022] Open
Abstract
Transposable elements (TEs) are genomic sequences that can move, multiply, and often form sizable fractions of vertebrate genomes. Fish belong to a unique group of vertebrates, since their karyotypes and genome sizes are more diverse and complex, with probably higher diversity and evolution specificity of TE. To investigate the characteristics of fish TEs, we compared the mobilomes of 39 species, and observed significant variation of TE content in fish (from 5% in pufferfish to 56% in zebrafish), along with a positive correlation between fish genome size and TE content. In different classification hierarchies, retrotransposons (class), long terminal repeat (order), as well as Helitron, Maverick, Kolobok, CMC, DIRS, P, I, L1, L2, and 5S (superfamily) were all positively correlated with fish genome size. Consistent with previous studies, our data suggested fish genomes to not always be dominated by DNA transposons; long interspersed nuclear elements are also prominent in many species. This study suggests CR1 distribution in fish genomes to be obviously regular, and provides new clues concerning important events in vertebrate evolution. Altogether, our results highlight the importance of TEs in the structure and evolution of fish genomes and suggest fish species diversity to parallel transposon content diversification.
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Ray DA, Grimshaw JR, Halsey MK, Korstian JM, Osmanski AB, Sullivan KAM, Wolf KA, Reddy H, Foley N, Stevens RD, Knisbacher BA, Levy O, Counterman B, Edelman NB, Mallet J. Simultaneous TE Analysis of 19 Heliconiine Butterflies Yields Novel Insights into Rapid TE-Based Genome Diversification and Multiple SINE Births and Deaths. Genome Biol Evol 2019; 11:2162-2177. [PMID: 31214686 PMCID: PMC6685494 DOI: 10.1093/gbe/evz125] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/11/2019] [Indexed: 12/21/2022] Open
Abstract
Transposable elements (TEs) play major roles in the evolution of genome structure and function. However, because of their repetitive nature, they are difficult to annotate and discovering the specific roles they may play in a lineage can be a daunting task. Heliconiine butterflies are models for the study of multiple evolutionary processes including phenotype evolution and hybridization. We attempted to determine how TEs may play a role in the diversification of genomes within this clade by performing a detailed examination of TE content and accumulation in 19 species whose genomes were recently sequenced. We found that TE content has diverged substantially and rapidly in the time since several subclades shared a common ancestor with each lineage harboring a unique TE repertoire. Several novel SINE lineages have been established that are restricted to a subset of species. Furthermore, the previously described SINE, Metulj, appears to have gone extinct in two subclades while expanding to significant numbers in others. This diversity in TE content and activity has the potential to impact how heliconiine butterflies continue to evolve and diverge.
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Affiliation(s)
- David A Ray
- Department of Biological Science, Texas Tech University
| | | | | | | | | | | | | | - Harsith Reddy
- Department of Biological Science, Texas Tech University
| | - Nicole Foley
- Department of Biological Science, Texas Tech University
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine, Texas A&M University, College Station, TX
| | | | - Binyamin A Knisbacher
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel
- Broad Institute of MIT and Harvard, Cambridge, MA
| | - Orr Levy
- Department of Physics, Bar-Ilan University, Ramat Gan, Israel
| | | | | | - James Mallet
- Department of Organismic and Evolutionary Biology, Harvard University
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16
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Casanova MF, Casanova EL. The modular organization of the cerebral cortex: Evolutionary significance and possible links to neurodevelopmental conditions. J Comp Neurol 2019; 527:1720-1730. [PMID: 30303529 PMCID: PMC6784310 DOI: 10.1002/cne.24554] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Revised: 08/22/2018] [Accepted: 09/21/2018] [Indexed: 12/11/2022]
Abstract
The recognition of discernible anatomical regularities that appear to self-organize during development makes apparent the modular organization of the cerebral cortex. The metabolic cost engendered in sustaining interneuronal communications has emphasized the viability of short connections among neighboring neurons. This pattern of connectivity establishes a microcircuit which is repeated in parallel throughout the cerebral cortex. This canonical circuit is contained within the smallest module of information processing of the cerebral cortex; one which Vernon Mountcastle called the minicolumn. Plasticity within the brain is accounted, in part, by the presence of weak linkages that allow minicolumns to process information from a variety of sources and to quickly adapt to environmental exigencies without a need for genetic change. Recent research suggests that interlaminar correlated firing between minicolumns during the decision phase of target selection provides for the emergence of some executive functions. Bottlenecks of information processing within this modular minicolumnar organization may account for a variety of mental disorders observed in neurodevelopmental conditions.
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Affiliation(s)
- Manuel F Casanova
- Department of Biomedical Sciences, University of South Carolina School of Medicine Greenville, Greenville, South Carolina
| | - Emily L Casanova
- Department of Pediatrics, Greenville Health System, Greenville, South Carolina
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Liu Y, El-Kassaby YA. Novel Insights into Plant Genome Evolution and Adaptation as Revealed through Transposable Elements and Non-Coding RNAs in Conifers. Genes (Basel) 2019; 10:genes10030228. [PMID: 30889931 PMCID: PMC6470726 DOI: 10.3390/genes10030228] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Revised: 03/08/2019] [Accepted: 03/11/2019] [Indexed: 01/03/2023] Open
Abstract
Plant genomes are punctuated by repeated bouts of proliferation of transposable elements (TEs), and these mobile bursts are followed by silencing and decay of most of the newly inserted elements. As such, plant genomes reflect TE-related genome expansion and shrinkage. In general, these genome activities involve two mechanisms: small RNA-mediated epigenetic repression and long-term mutational decay and deletion, that is, genome-purging. Furthermore, the spatial relationships between TE insertions and genes are an important force in shaping gene regulatory networks, their downstream metabolic and physiological outputs, and thus their phenotypes. Such cascading regulations finally set up a fitness differential among individuals. This brief review demonstrates factual evidence that unifies most updated conceptual frameworks covering genome size, architecture, epigenetic reprogramming, and gene expression. It aims to give an overview of the impact that TEs may have on genome and adaptive evolution and to provide novel insights into addressing possible causes and consequences of intimidating genome sizes (20⁻30 Gb) in a taxonomic group, conifers.
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Affiliation(s)
- Yang Liu
- Department of Forest and Conservation Sciences, The University of British Columbia, 2424 Main Mall, Vancouver, BC V6T 1Z4, Canada.
| | - Yousry A El-Kassaby
- Department of Forest and Conservation Sciences, The University of British Columbia, 2424 Main Mall, Vancouver, BC V6T 1Z4, Canada.
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18
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Manthey JD, Moyle RG, Boissinot S. Multiple and Independent Phases of Transposable Element Amplification in the Genomes of Piciformes (Woodpeckers and Allies). Genome Biol Evol 2018; 10:1445-1456. [PMID: 29850797 PMCID: PMC6007501 DOI: 10.1093/gbe/evy105] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/22/2018] [Indexed: 12/15/2022] Open
Abstract
The small and conserved genomes of birds are likely a result of flight-related metabolic constraints. Recombination-driven deletions and minimal transposable element (TE) expansions have led to continually shrinking genomes during evolution of many lineages of volant birds. Despite constraints of genome size in birds, we identified multiple waves of amplification of TEs in Piciformes (woodpeckers, honeyguides, toucans, and barbets). Relative to other bird species’ genomic TE abundance (< 10% of genome), we found ∼17–30% TE content in multiple clades within Piciformes. Several families of the retrotransposon superfamily chicken repeat 1 (CR1) expanded in at least three different waves of activity. The most recent CR1 expansions (∼4–7% of genome) preceded bursts of diversification in the woodpecker clade and in the American barbets + toucans clade. Additionally, we identified several thousand polymorphic CR1 insertions (hundreds per individual) in three closely related woodpecker species. Woodpecker CR1 insertion polymorphisms are maintained at lower frequencies than single nucleotide polymorphisms indicating that purifying selection is acting against additional CR1 copies and that these elements impose a fitness cost on their host. These findings provide evidence of large scale and ongoing TE activity in avian genomes despite continual constraint on genome size.
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Affiliation(s)
- Joseph D Manthey
- New York University Abu Dhabi, UAE.,Department of Biological Sciences, Texas Tech University
| | - Robert G Moyle
- Department of Ecology and Evolutionary Biology, Biodiversity Institute, University of Kansas
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19
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Danchin E, Pocheville A, Rey O, Pujol B, Blanchet S. Epigenetically facilitated mutational assimilation: epigenetics as a hub within the inclusive evolutionary synthesis. Biol Rev Camb Philos Soc 2018. [PMCID: PMC6378602 DOI: 10.1111/brv.12453] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
After decades of debate about the existence of non‐genetic inheritance, the focus is now slowly shifting towards dissecting its underlying mechanisms. Here, we propose a new mechanism that, by integrating non‐genetic and genetic inheritance, may help build the long‐sought inclusive vision of evolution. After briefly reviewing the wealth of evidence documenting the existence and ubiquity of non‐genetic inheritance in a table, we review the categories of mechanisms of parent–offspring resemblance that underlie inheritance. We then review several lines of argument for the existence of interactions between non‐genetic and genetic components of inheritance, leading to a discussion of the contrasting timescales of action of non‐genetic and genetic inheritance. This raises the question of how the fidelity of the inheritance system can match the rate of environmental variation. This question is central to understanding the role of different inheritance systems in evolution. We then review and interpret evidence indicating the existence of shifts from inheritance systems with low to higher transmission fidelity. Based on results from different research fields we propose a conceptual hypothesis linking genetic and non‐genetic inheritance systems. According to this hypothesis, over the course of generations, shifts among information systems allow gradual matching between the rate of environmental change and the inheritance fidelity of the corresponding response. A striking conclusion from our review is that documented shifts between types of inherited non‐genetic information converge towards epigenetics (i.e. inclusively heritable molecular variation in gene expression without change in DNA sequence). We then interpret the well‐documented mutagenicity of epigenetic marks as potentially generating a final shift from epigenetic to genetic encoding. This sequence of shifts suggests the existence of a relay in inheritance systems from relatively labile ones to gradually more persistent modes of inheritance, a relay that could constitute a new mechanistic basis for the long‐proposed, but still poorly documented, hypothesis of genetic assimilation. A profound difference between the genocentric and the inclusive vision of heredity revealed by the genetic assimilation relay proposed here lies in the fact that a given form of inheritance can affect the rate of change of other inheritance systems. To explore the consequences of such inter‐connection among inheritance systems, we briefly review published theoretical models to build a model of genetic assimilation focusing on the shift in the engraving of environmentally induced phenotypic variation into the DNA sequence. According to this hypothesis, when environmental change remains stable over a sufficient number of generations, the relay among inheritance systems has the potential to generate a form of genetic assimilation. In this hypothesis, epigenetics appears as a hub by which non‐genetically inherited environmentally induced variation in traits can become genetically encoded over generations, in a form of epigenetically facilitated mutational assimilation. Finally, we illustrate some of the major implications of our hypothetical framework, concerning mutation randomness, the central dogma of molecular biology, concepts of inheritance and the curing of inherited disorders, as well as for the emergence of the inclusive evolutionary synthesis.
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Affiliation(s)
- Etienne Danchin
- Laboratoire Évolution & Diversité Biologique (EDB UMR 5174); Université de Toulouse Midi-Pyrénées, CNRS, IRD, UPS. 118 route de Narbonne, Bat 4R1; 31062 Toulouse Cedex 9 France
| | - Arnaud Pocheville
- Laboratoire Évolution & Diversité Biologique (EDB UMR 5174); Université de Toulouse Midi-Pyrénées, CNRS, IRD, UPS. 118 route de Narbonne, Bat 4R1; 31062 Toulouse Cedex 9 France
- Department of Philosophy and Charles Perkins Centre; University of Sydney; Sydney NSW 2006 Australia
| | - Olivier Rey
- CNRS, Station d'Ecologie Théorique et Expérimentale (SETE), UMR5321; 09200 Moulis France
- Université de Perpignan Via Domitia, IHPE UMR 5244, CNRS, IFREMER, Université de Montpellier; F-66860 Perpignan France
| | - Benoit Pujol
- Laboratoire Évolution & Diversité Biologique (EDB UMR 5174); Université de Toulouse Midi-Pyrénées, CNRS, IRD, UPS. 118 route de Narbonne, Bat 4R1; 31062 Toulouse Cedex 9 France
| | - Simon Blanchet
- Laboratoire Évolution & Diversité Biologique (EDB UMR 5174); Université de Toulouse Midi-Pyrénées, CNRS, IRD, UPS. 118 route de Narbonne, Bat 4R1; 31062 Toulouse Cedex 9 France
- CNRS, Station d'Ecologie Théorique et Expérimentale (SETE), UMR5321; 09200 Moulis France
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20
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Schrader L, Schmitz J. The impact of transposable elements in adaptive evolution. Mol Ecol 2018; 28:1537-1549. [PMID: 30003608 DOI: 10.1111/mec.14794] [Citation(s) in RCA: 134] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Accepted: 07/06/2018] [Indexed: 12/16/2022]
Abstract
The growing knowledge about the influence of transposable elements (TEs) on (a) long-term genome and transcriptome evolution; (b) genomic, transcriptomic and epigenetic variation within populations; and (c) patterns of somatic genetic differences in individuals continues to spur the interest of evolutionary biologists in the role of TEs in adaptive evolution. As TEs can trigger a broad range of molecular variation in a population with potentially severe fitness and phenotypic consequences for individuals, different mechanisms evolved to keep TE activity in check, allowing for a dynamic interplay between the host, its TEs and the environment in evolution. Here, we review evidence for adaptive phenotypic changes associated with TEs and the basic molecular mechanisms by which the underlying genetic changes arise: (a) domestication, (b) exaptation, (c) host gene regulation, (d) TE-mediated formation of intronless gene copies-so-called retrogenes and (e) overall increased genome plasticity. Furthermore, we review and discuss how the stress-dependent incapacitation of defence mechanisms against the activity of TEs might facilitate adaptive responses to environmental challenges and how such mechanisms might be particularly relevant in species frequently facing novel environments, such as invasive, pathogenic or parasitic species.
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Affiliation(s)
- Lukas Schrader
- Institute for Evolution and Biodiversity (IEB), University of Münster, Münster, Germany
| | - Jürgen Schmitz
- Institute of Experimental Pathology, University of Münster, Münster, Germany
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21
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Sookdeo A, Ruiz-García M, Schneider H, Boissinot S. Contrasting Rates of LINE-1 Amplification among New World Primates of the Atelidae Family. Cytogenet Genome Res 2018; 154:217-228. [PMID: 29991050 DOI: 10.1159/000490481] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/13/2018] [Indexed: 11/19/2022] Open
Abstract
LINE-1 (L1) retrotransposons constitute the dominant category of transposons in mammalian genomes. L1 elements are active in the vast majority of mammals, and only a few cases of L1 extinction have been documented. The only possible case of extinction in primates was suggested for South American spider monkeys. However, these previous studies were based on a single species. We revisited this question with a larger phylogenetic sample, covering all 4 genera of Atelidae and 3 species of spider monkeys. We used an enrichment method to clone recently inserted L1 elements and performed an evolutionary analysis of the sequences. We were able to identify young L1 elements in all taxa, suggesting that L1 is probably still active in all Atelidae examined. However, we also detected considerable variations in the proportion of recent elements indicating that the rate of L1 amplification varies among Atelidae by a 3-fold factor. The extent of L1 amplification in Atelidae remains overall lower than in other New World monkeys. Multiple factors can affect the amplification of L1, such as the demography of the host and the control of transposition. These factors are discussed in the context of host life history.
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Abstract
Transposable elements (TEs) are mobile genetic elements that were once perceived as merely selfish, but are now recognized as potent agents of adaptation. One way TEs contribute to genome evolution is through TE exaptation, a process whereby TEs, which usually persist by replicating in the genome, transform into novel host genes, which thereafter persist by conferring phenotypic benefits. Exapted TEs are known to contribute diverse and vital functions, and may facilitate punctuated equilibrium, yet we have little understanding about the process of TE exaptation. In order to facilitate our understanding of how TE coding sequences may become exapted, here we incorporate the findings of recent publications into a framework and six-step model.
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Affiliation(s)
- Zoé Joly-Lopez
- Center for Genomics and Systems Biology, Department of Biology, New York University, New York, NY 10003, USA
| | - Thomas E Bureau
- Department of Biology, McGill University, Montreal, QC H3A 1B1, Canada.
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23
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Larsen PA, Hunnicutt KE, Larsen RJ, Yoder AD, Saunders AM. Warning SINEs: Alu elements, evolution of the human brain, and the spectrum of neurological disease. Chromosome Res 2018; 26:93-111. [PMID: 29460123 PMCID: PMC5857278 DOI: 10.1007/s10577-018-9573-4] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2017] [Revised: 01/14/2018] [Accepted: 01/15/2018] [Indexed: 12/28/2022]
Abstract
Alu elements are a highly successful family of primate-specific retrotransposons that have fundamentally shaped primate evolution, including the evolution of our own species. Alus play critical roles in the formation of neurological networks and the epigenetic regulation of biochemical processes throughout the central nervous system (CNS), and thus are hypothesized to have contributed to the origin of human cognition. Despite the benefits that Alus provide, deleterious Alu activity is associated with a number of neurological and neurodegenerative disorders. In particular, neurological networks are potentially vulnerable to the epigenetic dysregulation of Alu elements operating across the suite of nuclear-encoded mitochondrial genes that are critical for both mitochondrial and CNS function. Here, we highlight the beneficial neurological aspects of Alu elements as well as their potential to cause disease by disrupting key cellular processes across the CNS. We identify at least 37 neurological and neurodegenerative disorders wherein deleterious Alu activity has been implicated as a contributing factor for the manifestation of disease, and for many of these disorders, this activity is operating on genes that are essential for proper mitochondrial function. We conclude that the epigenetic dysregulation of Alu elements can ultimately disrupt mitochondrial homeostasis within the CNS. This mechanism is a plausible source for the incipient neuronal stress that is consistently observed across a spectrum of sporadic neurological and neurodegenerative disorders.
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Affiliation(s)
- Peter A Larsen
- Department of Biology, Duke University, Durham, NC, 27708, USA.
- Duke Lemur Center, Duke University, Durham, NC, 27708, USA.
- Department of Biology, Duke University, 130 Science Drive, Box 90338, Durham, NC, 27708, USA.
| | | | - Roxanne J Larsen
- Duke University School of Medicine, Duke University, Durham, NC, 27710, USA
| | - Anne D Yoder
- Department of Biology, Duke University, Durham, NC, 27708, USA
- Duke Lemur Center, Duke University, Durham, NC, 27708, USA
| | - Ann M Saunders
- Zinfandel Pharmaceuticals Inc, Chapel Hill, NC, 27709, USA
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Platt RN, Vandewege MW, Ray DA. Mammalian transposable elements and their impacts on genome evolution. Chromosome Res 2018; 26:25-43. [PMID: 29392473 PMCID: PMC5857283 DOI: 10.1007/s10577-017-9570-z] [Citation(s) in RCA: 139] [Impact Index Per Article: 23.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Revised: 12/12/2017] [Accepted: 12/28/2017] [Indexed: 12/22/2022]
Abstract
Transposable elements (TEs) are genetic elements with the ability to mobilize and replicate themselves in a genome. Mammalian genomes are dominated by TEs, which can reach copy numbers in the hundreds of thousands. As a result, TEs have had significant impacts on mammalian evolution. Here we summarize the current understanding of TE content in mammal genomes and find that, with a few exceptions, most fall within a predictable range of observations. First, one third to one half of the genome is derived from TEs. Second, most mammalian genomes are dominated by LINE and SINE retrotransposons, more limited LTR retrotransposons, and minimal DNA transposon accumulation. Third, most mammal genome contains at least one family of actively accumulating retrotransposon. Finally, horizontal transfer of TEs among lineages is rare. TE exaptation events are being recognized with increasing frequency. Despite these beneficial aspects of TE content and activity, the majority of TE insertions are neutral or deleterious. To limit the deleterious effects of TE proliferation, the genome has evolved several defense mechanisms that act at the epigenetic, transcriptional, and post-transcriptional levels. The interaction between TEs and these defense mechanisms has led to an evolutionary arms race where TEs are suppressed, evolve to escape suppression, then are suppressed again as the defense mechanisms undergo compensatory change. The result is complex and constantly evolving interactions between TEs and host genomes.
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Affiliation(s)
- Roy N Platt
- Department of Biological Sciences, Texas Tech University, Lubbock, TX, USA.
| | | | - David A Ray
- Department of Biological Sciences, Texas Tech University, Lubbock, TX, USA
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25
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Shapiro JA. Living Organisms Author Their Read-Write Genomes in Evolution. BIOLOGY 2017; 6:E42. [PMID: 29211049 PMCID: PMC5745447 DOI: 10.3390/biology6040042] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 08/23/2017] [Revised: 11/17/2017] [Accepted: 11/28/2017] [Indexed: 12/18/2022]
Abstract
Evolutionary variations generating phenotypic adaptations and novel taxa resulted from complex cellular activities altering genome content and expression: (i) Symbiogenetic cell mergers producing the mitochondrion-bearing ancestor of eukaryotes and chloroplast-bearing ancestors of photosynthetic eukaryotes; (ii) interspecific hybridizations and genome doublings generating new species and adaptive radiations of higher plants and animals; and, (iii) interspecific horizontal DNA transfer encoding virtually all of the cellular functions between organisms and their viruses in all domains of life. Consequently, assuming that evolutionary processes occur in isolated genomes of individual species has become an unrealistic abstraction. Adaptive variations also involved natural genetic engineering of mobile DNA elements to rewire regulatory networks. In the most highly evolved organisms, biological complexity scales with "non-coding" DNA content more closely than with protein-coding capacity. Coincidentally, we have learned how so-called "non-coding" RNAs that are rich in repetitive mobile DNA sequences are key regulators of complex phenotypes. Both biotic and abiotic ecological challenges serve as triggers for episodes of elevated genome change. The intersections of cell activities, biosphere interactions, horizontal DNA transfers, and non-random Read-Write genome modifications by natural genetic engineering provide a rich molecular and biological foundation for understanding how ecological disruptions can stimulate productive, often abrupt, evolutionary transformations.
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Affiliation(s)
- James A Shapiro
- Department of Biochemistry and Molecular Biology, University of Chicago GCIS W123B, 979 E. 57th Street, Chicago, IL 60637, USA.
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The "evolutionary field" hypothesis. Non-Mendelian transgenerational inheritance mediates diversification and evolution. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2017; 134:27-37. [PMID: 29223657 DOI: 10.1016/j.pbiomolbio.2017.12.001] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2017] [Revised: 11/17/2017] [Accepted: 12/05/2017] [Indexed: 12/23/2022]
Abstract
Epigenetics is increasingly regarded as a potential contributing factor to evolution. Building on apparently unrelated results, here I propose that RNA-containing nanovesicles, predominantly small regulatory RNAs, are released from somatic tissues in the bloodstream, cross the Weismann barrier, reach the epididymis, and are eventually taken up by spermatozoa; henceforth the information is delivered to oocytes at fertilization. In the model, a LINE-1-encoded reverse transcriptase activity, present in spermatozoa and early embryos, plays a key role in amplifying and propagating these RNAs as extrachromosomal structures. It may be conceived that, over generations, the cumulative effects of sperm-delivered RNAs would cross a critical threshold and overcome the buffering capacity of embryos. As a whole, the process can promote the generation of an information-containing platform that drives the reshaping of the embryonic epigenetic landscape with the potential to generate ontogenic changes and redirect the evolutionary trajectory. Over time, evolutionary significant, stably acquired variations could be generated through the process. The interplay between these elements defines the concept of "evolutionary field", a self-consistent, comprehensive information-containing platform and a source of discontinuous evolutionary novelty.
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Miller WB. Biological information systems: Evolution as cognition-based information management. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2017; 134:1-26. [PMID: 29175233 DOI: 10.1016/j.pbiomolbio.2017.11.005] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2017] [Revised: 11/16/2017] [Accepted: 11/21/2017] [Indexed: 01/08/2023]
Abstract
An alternative biological synthesis is presented that conceptualizes evolutionary biology as an epiphenomenon of integrated self-referential information management. Since all biological information has inherent ambiguity, the systematic assessment of information is required by living organisms to maintain self-identity and homeostatic equipoise in confrontation with environmental challenges. Through their self-referential attachment to information space, cells are the cornerstone of biological action. That individualized assessment of information space permits self-referential, self-organizing niche construction. That deployment of information and its subsequent selection enacted the dominant stable unicellular informational architectures whose biological expressions are the prokaryotic, archaeal, and eukaryotic unicellular forms. Multicellularity represents the collective appraisal of equivocal environmental information through a shared information space. This concerted action can be viewed as systematized information management to improve information quality for the maintenance of preferred homeostatic boundaries among the varied participants. When reiterated in successive scales, this same collaborative exchange of information yields macroscopic organisms as obligatory multicellular holobionts. Cognition-Based Evolution (CBE) upholds that assessment of information precedes biological action, and the deployment of information through integrative self-referential niche construction and natural cellular engineering antecedes selection. Therefore, evolutionary biology can be framed as a complex reciprocating interactome that consists of the assessment, communication, deployment and management of information by self-referential organisms at multiple scales in continuous confrontation with environmental stresses.
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Luchetti A, Plazzi F, Mantovani B. Evolution of Two Short Interspersed Elements in Callorhinchus milii (Chondrichthyes, Holocephali) and Related Elements in Sharks and the Coelacanth. Genome Biol Evol 2017; 9:3824762. [PMID: 28505260 PMCID: PMC5499810 DOI: 10.1093/gbe/evx094] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/11/2017] [Indexed: 12/11/2022] Open
Abstract
Short interspersed elements (SINEs) are non-autonomous retrotransposons. Although they usually show fast evolutionary rates, in some instances highly conserved domains (HCDs) have been observed in elements with otherwise divergent sequences and from distantly related species. Here, we document the life history of two HCD-SINE families in the elephant shark Callorhinchus milii, one specific to the holocephalan lineage (CmiSINEs) and another one (SacSINE1-CM) with homologous elements in sharks and the coelacanth (SacSINE1s, LmeSINE1s). The analyses of their relationships indicated that these elements share the same 3′-tail, which would have allowed both elements to rise to high copy number by exploiting the C. milii L2-2_CM long interspersed element (LINE) enzymes. Molecular clock analysis on SINE activity in C. milii genome evidenced two replication bursts occurring right after two major events in the holocephalan evolution: the end-Permian mass extinction and the radiation of modern Holocephali. Accordingly, the same analysis on the coelacanth homologous elements, LmeSINE1, identified a replication wave close to the split age of the two extant Latimeria species. The genomic distribution of the studied SINEs pointed out contrasting results: some elements were preferentially sorted out from gene regions, but accumulated in flanking regions, while others appear more conserved within genes. Moreover, data from the C. milii transcriptome suggest that these SINEs could be involved in miRNA biogenesis and may be targets for miRNA-based regulation.
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Affiliation(s)
- Andrea Luchetti
- Dipartimento di Scienze Biologiche, Geologiche e Ambientali - Università di Bologna, Italy
| | - Federico Plazzi
- Dipartimento di Scienze Biologiche, Geologiche e Ambientali - Università di Bologna, Italy
| | - Barbara Mantovani
- Dipartimento di Scienze Biologiche, Geologiche e Ambientali - Università di Bologna, Italy
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Wolff F, Leisch M, Greil R, Risch A, Pleyer L. The double-edged sword of (re)expression of genes by hypomethylating agents: from viral mimicry to exploitation as priming agents for targeted immune checkpoint modulation. Cell Commun Signal 2017; 15:13. [PMID: 28359286 PMCID: PMC5374693 DOI: 10.1186/s12964-017-0168-z] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Accepted: 03/21/2017] [Indexed: 12/20/2022] Open
Abstract
Hypomethylating agents (HMAs) have been widely used over the last decade, approved for use in myelodysplastic syndrome (MDS), chronic myelomonocytic leukemia (CMML) and acute myeloid leukemia (AML). The proposed central mechanism of action of HMAs, is the reversal of aberrant methylation in tumor cells, thus reactivating CpG-island promoters and leading to (re)expression of tumor suppressor genes. Recent investigations into the mode of action of azacitidine (AZA) and decitabine (DAC) have revealed new molecular mechanisms that impinge on tumor immunity via induction of an interferon response, through activation of endogenous retroviral elements (ERVs) that are normally epigenetically silenced. Although the global demethylation of DNA by HMAs can induce anti-tumor effects, it can also upregulate the expression of inhibitory immune checkpoint receptors and their ligands, resulting in secondary resistance to HMAs. Recent studies have, however, suggested that this could be exploited to prime or (re)sensitize tumors to immune checkpoint inhibitor therapies. In recent years, immune checkpoints have been targeted by novel therapies, with the aim of (re)activating the host immune system to specifically eliminate malignant cells. Antibodies blocking checkpoint receptors have been FDA-approved for some solid tumors and a plethora of clinical trials testing these and other checkpoint inhibitors are under way. This review will discuss AZA and DAC novel mechanisms of action resulting from the re-expression of pathologically hypermethylated promoters of gene sets that are related to interferon signaling, antigen presentation and inflammation. We also review new insights into the molecular mechanisms of action of transient, low-dose HMAs on various tumor types and discuss the potential of new treatment options and combinations.
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Affiliation(s)
- Florian Wolff
- Department of Molecular Biology, University of Salzburg, Salzburg, Austria
| | - Michael Leisch
- 3rd Medical Department with Hematology and Medical Oncology, Hemostaseology, Rheumatology and Infectious Diseases, Laboratory for Immunological and Molecular Cancer Research, Oncologic Center, Paracelsus Medical University Salzburg, Müllner Hauptstraße 48, A-5020, Salzburg, Austria
| | - Richard Greil
- 3rd Medical Department with Hematology and Medical Oncology, Hemostaseology, Rheumatology and Infectious Diseases, Laboratory for Immunological and Molecular Cancer Research, Oncologic Center, Paracelsus Medical University Salzburg, Müllner Hauptstraße 48, A-5020, Salzburg, Austria.,Salzburg Cancer Research Institute - Center for Clinical Cancer and Immunology Trials, Salzburg, Austria.,Cancer Cluster Salzburg, Salzburg, Austria
| | - Angela Risch
- Department of Molecular Biology, University of Salzburg, Salzburg, Austria.,Cancer Cluster Salzburg, Salzburg, Austria
| | - Lisa Pleyer
- 3rd Medical Department with Hematology and Medical Oncology, Hemostaseology, Rheumatology and Infectious Diseases, Laboratory for Immunological and Molecular Cancer Research, Oncologic Center, Paracelsus Medical University Salzburg, Müllner Hauptstraße 48, A-5020, Salzburg, Austria. .,Salzburg Cancer Research Institute - Center for Clinical Cancer and Immunology Trials, Salzburg, Austria. .,Cancer Cluster Salzburg, Salzburg, Austria.
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Sotero-Caio CG, Platt RN, Suh A, Ray DA. Evolution and Diversity of Transposable Elements in Vertebrate Genomes. Genome Biol Evol 2017; 9:161-177. [PMID: 28158585 PMCID: PMC5381603 DOI: 10.1093/gbe/evw264] [Citation(s) in RCA: 147] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/06/2016] [Indexed: 12/21/2022] Open
Abstract
Transposable elements (TEs) are selfish genetic elements that mobilize in genomes via transposition or retrotransposition and often make up large fractions of vertebrate genomes. Here, we review the current understanding of vertebrate TE diversity and evolution in the context of recent advances in genome sequencing and assembly techniques. TEs make up 4-60% of assembled vertebrate genomes, and deeply branching lineages such as ray-finned fishes and amphibians generally exhibit a higher TE diversity than the more recent radiations of birds and mammals. Furthermore, the list of taxa with exceptional TE landscapes is growing. We emphasize that the current bottleneck in genome analyses lies in the proper annotation of TEs and provide examples where superficial analyses led to misleading conclusions about genome evolution. Finally, recent advances in long-read sequencing will soon permit access to TE-rich genomic regions that previously resisted assembly including the gigantic, TE-rich genomes of salamanders and lungfishes.
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Affiliation(s)
| | - Roy N. Platt
- Department of Biological Sciences, Texas Tech University, Lubbock, TX
| | - Alexander Suh
- Department of Evolutionary Biology (EBC), Uppsala University, Uppsala, Sweden
| | - David A. Ray
- Department of Biological Sciences, Texas Tech University, Lubbock, TX
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Farré D, Engel P, Angulo A. Novel Role of 3'UTR-Embedded Alu Elements as Facilitators of Processed Pseudogene Genesis and Host Gene Capture by Viral Genomes. PLoS One 2016; 11:e0169196. [PMID: 28033411 PMCID: PMC5199112 DOI: 10.1371/journal.pone.0169196] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Accepted: 12/13/2016] [Indexed: 11/19/2022] Open
Abstract
Since the discovery of the high abundance of Alu elements in the human genome, the interest for the functional significance of these retrotransposons has been increasing. Primate Alu and rodent Alu-like elements are retrotransposed by a mechanism driven by the LINE1 (L1) encoded proteins, the same machinery that generates the L1 repeats, the processed pseudogenes (PPs), and other retroelements. Apart from free Alu RNAs, Alus are also transcribed and retrotranscribed as part of cellular gene transcripts, generally embedded inside 3' untranslated regions (UTRs). Despite different proposed hypotheses, the functional implication of the presence of Alus inside 3'UTRs remains elusive. In this study we hypothesized that Alu elements in 3'UTRs could be involved in the genesis of PPs. By analyzing human genome data we discovered that the existence of 3'UTR-embedded Alu elements is overrepresented in genes source of PPs. In contrast, the presence of other retrotransposable elements in 3'UTRs does not show this PP linked overrepresentation. This research was extended to mouse and rat genomes and the results accordingly reveal overrepresentation of 3'UTR-embedded B1 (Alu-like) elements in PP parent genes. Interestingly, we also demonstrated that the overrepresentation of 3'UTR-embedded Alus is particularly significant in PP parent genes with low germline gene expression level. Finally, we provide data that support the hypothesis that the L1 machinery is also the system that herpesviruses, and possibly other large DNA viruses, use to capture host genes expressed in germline or somatic cells. Altogether our results suggest a novel role for Alu or Alu-like elements inside 3'UTRs as facilitators of the genesis of PPs, particularly in lowly expressed genes. Moreover, we propose that this L1-driven mechanism, aided by the presence of 3'UTR-embedded Alus, may also be exploited by DNA viruses to incorporate host genes to their viral genomes.
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Affiliation(s)
- Domènec Farré
- Immunology Unit, Department of Biomedical Sciences, Medical School, University of Barcelona, Barcelona, Spain
- Institut d’Investigacions Biomèdiques August Pi i Sunyer, Barcelona, Spain
- * E-mail:
| | - Pablo Engel
- Immunology Unit, Department of Biomedical Sciences, Medical School, University of Barcelona, Barcelona, Spain
- Institut d’Investigacions Biomèdiques August Pi i Sunyer, Barcelona, Spain
| | - Ana Angulo
- Immunology Unit, Department of Biomedical Sciences, Medical School, University of Barcelona, Barcelona, Spain
- Institut d’Investigacions Biomèdiques August Pi i Sunyer, Barcelona, Spain
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32
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Shapiro JA. Exploring the read-write genome: mobile DNA and mammalian adaptation. Crit Rev Biochem Mol Biol 2016; 52:1-17. [DOI: 10.1080/10409238.2016.1226748] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- James A. Shapiro
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL, USA
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Platt RN, Mangum SF, Ray DA. Pinpointing the vesper bat transposon revolution using the Miniopterus natalensis genome. Mob DNA 2016; 7:12. [PMID: 27489570 PMCID: PMC4971623 DOI: 10.1186/s13100-016-0071-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Accepted: 07/13/2016] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND Around 40 million years ago DNA transposons began accumulating in an ancestor of bats in the family Vespertilionidae. Since that time, Class II transposons have been continuously reinvading and accumulating in vespertilionid genomes at a rate that is unprecedented in mammals. Miniopterus (Miniopteridae), a genus of long-fingered bats that was recently elevated from Vespertilionidae, is the sister taxon to the vespertilionids and is often used as an outgroup when studying transposable elements in vesper bats. Previous wet-lab techniques failed to identify Helitrons, TcMariners, or hAT transposons in Miniopterus. Limitations of those methods and ambiguous results regarding the distribution of piggyBac transposons left some questions as to the distribution of Class II elements in this group. The recent release of the Miniopterus natalensis genome allows for transposable element discovery with a higher degree of precision. RESULTS Here we analyze the transposable element content of M. natalensis to pinpoint with greater accuracy the taxonomic distribution of Class II transposable elements in bats. These efforts demonstrate that, compared to the vespertilionids, Class II TEs are highly mutated and comprise only a small portion of the M. natalensis genome. Despite the limited Class II content, M. natalensis possesses a limited number of lineage-specific, low copy number piggyBacs and shares several TcMariner families with vespertilionid bats. Multiple efforts to identify Helitrons, one of the major TE components of vesper bat genomes, using de novo repeat identification and structural based searches failed. CONCLUSIONS These observations combined with previous results inform our understanding of the events leading to the unique Class II element acquisition that characterizes vespertilionids. While it appears that a small number of TcMariner and piggyBac elements were deposited in the ancestral Miniopterus + vespertilionid genome, these elements are not present in M. natalensis genome at high copy number. Instead, this work indicates that the vesper bats alone experienced the expansion of TEs ranging from Helitrons to piggyBacs to hATs.
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Affiliation(s)
- Roy N Platt
- Department of Biological Sciences, Texas Tech University, Box 43131, Lubbock, TX 79409-3131 USA
| | - Sarah F Mangum
- Department of Biological Sciences, Texas Tech University, Box 43131, Lubbock, TX 79409-3131 USA
| | - David A Ray
- Department of Biological Sciences, Texas Tech University, Box 43131, Lubbock, TX 79409-3131 USA
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Spadafora C. Soma to germline inheritance of extrachromosomal genetic information via a LINE-1 reverse transcriptase-based mechanism. Bioessays 2016; 38:726-33. [DOI: 10.1002/bies.201500197] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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35
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The Unicellular State as a Point Source in a Quantum Biological System. BIOLOGY 2016; 5:biology5020025. [PMID: 27240413 PMCID: PMC4929539 DOI: 10.3390/biology5020025] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Revised: 05/04/2016] [Accepted: 05/23/2016] [Indexed: 01/03/2023]
Abstract
A point source is the central and most important point or place for any group of cohering phenomena. Evolutionary development presumes that biological processes are sequentially linked, but neither directed from, nor centralized within, any specific biologic structure or stage. However, such an epigenomic entity exists and its transforming effects can be understood through the obligatory recapitulation of all eukaryotic lifeforms through a zygotic unicellular phase. This requisite biological conjunction can now be properly assessed as the focal point of reconciliation between biology and quantum phenomena, illustrated by deconvoluting complex physiologic traits back to their unicellular origins.
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Rey O, Danchin E, Mirouze M, Loot C, Blanchet S. Adaptation to Global Change: A Transposable Element-Epigenetics Perspective. Trends Ecol Evol 2016; 31:514-526. [PMID: 27080578 DOI: 10.1016/j.tree.2016.03.013] [Citation(s) in RCA: 109] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2015] [Revised: 03/11/2016] [Accepted: 03/14/2016] [Indexed: 12/21/2022]
Abstract
Understanding how organisms cope with global change is a major scientific challenge. The molecular pathways underlying rapid adaptive phenotypic responses to global change remain poorly understood. Here, we highlight the relevance of two environment-sensitive molecular elements: transposable elements (TEs) and epigenetic components (ECs). We first outline the sensitivity of these elements to global change stressors and review how they interact with each other. We then propose an integrative molecular engine coupling TEs and ECs and allowing organisms to fine-tune phenotypes in a real-time fashion, adjust the production of phenotypic and genetic variation, and produce heritable phenotypes with different levels of transmission fidelity. We finally discuss the implications of this molecular engine in the context of global change.
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Affiliation(s)
- Olivier Rey
- CNRS, UPS, Station d'Écologie Théorique et Expérimentale, UMR 5321, 09200 Moulis, France; Department of Biosciences, College of Science, Swansea University, Swansea SA2 8PP, UK.
| | - Etienne Danchin
- CNRS, UPS, ENFA, Évolution & Diversité Biologique (EDB) UMR 5174, 118 Route de Narbonne, 31062 Toulouse, Cedex 9, France; Université Paul Sabatier, Évolution & Diversité Biologique (EDB), 31062 Toulouse, Cedex 9, France
| | - Marie Mirouze
- Institut de Recherche pour le Développement, UMR232 DIADE Diversité Adaptation et Développement des Plantes, Laboratoire Génome et Développement des Plantes, 58 avenue Paul Alduy, 66860 Perpignan, France
| | - Céline Loot
- Institut Pasteur, Unité de Plasticité du Génome Bactérien, Paris, France; CNRS UMR3525, Paris, France
| | - Simon Blanchet
- CNRS, UPS, Station d'Écologie Théorique et Expérimentale, UMR 5321, 09200 Moulis, France; CNRS, UPS, ENFA, Évolution & Diversité Biologique (EDB) UMR 5174, 118 Route de Narbonne, 31062 Toulouse, Cedex 9, France.
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Sciamanna I, De Luca C, Spadafora C. The Reverse Transcriptase Encoded by LINE-1 Retrotransposons in the Genesis, Progression, and Therapy of Cancer. Front Chem 2016; 4:6. [PMID: 26904537 PMCID: PMC4749692 DOI: 10.3389/fchem.2016.00006] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Accepted: 01/26/2016] [Indexed: 12/24/2022] Open
Abstract
In higher eukaryotic genomes, Long Interspersed Nuclear Element 1 (LINE-1) retrotransposons represent a large family of repeated genomic elements. They transpose using a reverse transcriptase (RT), which they encode as part of the ORF2p product. RT inhibition in cancer cells, either via RNA interference-dependent silencing of active LINE-1 elements, or using RT inhibitory drugs, reduces cancer cell proliferation, promotes their differentiation and antagonizes tumor progression in animal models. Indeed, the non-nucleoside RT inhibitor efavirenz has recently been tested in a phase II clinical trial with metastatic prostate cancer patients. An in-depth analysis of ORF2p in a mouse model of breast cancer showed ORF2p to be precociously expressed in precancerous lesions and highly abundant in advanced cancer stages, while being barely detectable in normal breast tissue, providing a rationale for the finding that RT-expressing tumors are therapeutically sensitive to RT inhibitors. We summarize mechanistic and gene profiling studies indicating that abundant LINE-1-derived RT can “sequester” RNA substrates for reverse transcription in tumor cells, entailing the formation of RNA:DNA hybrid molecules and impairing the overall production of regulatory miRNAs, with a global impact on the cell transcriptome. Based on these data, LINE-1-ORF2 encoded RT has a tumor-promoting potential that is exerted at an epigenetic level. We propose a model whereby LINE1-RT drives a previously unrecognized global regulatory process, the deregulation of which drives cell transformation and tumorigenesis with possible implications for cancer cell heterogeneity.
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Affiliation(s)
| | | | - Corrado Spadafora
- Institute of Translational Pharmacology, National Resarch Council of Italy Rome, Italy
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Brunet TDP, Doolittle WF. Multilevel Selection Theory and the Evolutionary Functions of Transposable Elements. Genome Biol Evol 2015; 7:2445-57. [PMID: 26253318 PMCID: PMC4558868 DOI: 10.1093/gbe/evv152] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
One of several issues at play in the renewed debate over “junk DNA” is the organizational level at which genomic features might be seen as selected, and thus to exhibit function, as etiologically defined. The intuition frequently expressed by molecular geneticists that junk DNA is functional because it serves to “speed evolution” or as an “evolutionary repository” could be recast as a claim about selection between species (or clades) rather than within them, but this is not often done. Here, we review general arguments for the importance of selection at levels above that of organisms in evolution, and develop them further for a common genomic feature: the carriage of transposable elements (TEs). In many species, not least our own, TEs comprise a large fraction of all nuclear DNA, and whether they individually or collectively contribute to fitness—or are instead junk— is a subject of ongoing contestation. Even if TEs generally owe their origin to selfish selection at the lowest level (that of genomes), their prevalence in extant organisms and the prevalence of extant organisms bearing them must also respond to selection within species (on organismal fitness) and between species (on rates of speciation and extinction). At an even higher level, the persistence of clades may be affected (positively or negatively) by TE carriage. If indeed TEs speed evolution, it is at these higher levels of selection that such a function might best be attributed to them as a class.
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Affiliation(s)
- Tyler D P Brunet
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - W Ford Doolittle
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Nova Scotia, Canada
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39
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A systemic approach for modeling biological evolution using Parallel DEVS. Biosystems 2015; 134:56-70. [DOI: 10.1016/j.biosystems.2015.06.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2014] [Revised: 03/26/2015] [Accepted: 06/17/2015] [Indexed: 12/22/2022]
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Hoffmann FG, McGuire LP, Counterman BA, Ray DA. Transposable elements and small RNAs: Genomic fuel for species diversity. Mob Genet Elements 2015; 5:63-66. [PMID: 26904375 DOI: 10.1080/2159256x.2015.1066919] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Revised: 05/20/2015] [Accepted: 06/23/2015] [Indexed: 12/15/2022] Open
Abstract
While transposable elements (TE) have long been suspected of involvement in species diversification, identifying specific roles has been difficult. We recently found evidence of TE-derived regulatory RNAs in a species-rich family of bats. The TE-derived small RNAs are temporally associated with the burst of species diversification, suggesting that they may have been involved in the processes that led to the diversification. In this commentary, we expand on the ideas that were briefly touched upon in that manuscript. Specifically, we suggest avenues of research that may help to identify the roles that TEs may play in perturbing regulatory pathways. Such research endeavors may serve to inform evolutionary biologists of the ways that TEs have influenced the genomic and taxonomic diversity around us.
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Affiliation(s)
- Federico G Hoffmann
- Department of Biochemistry, Molecular Biology, Entomology and Plant Pathology; Mississippi State University; Mississippi State, MS USA; Institute for Genomics, Biocomputing, and Biotechnology; Mississippi State University; Mississippi State, MS USA
| | - Liam P McGuire
- Department of Biological Sciences; Texas Tech University ; Lubbock, TX USA
| | - Brian A Counterman
- Department of Biological Sciences; Mississippi State University ; Mississippi State, MS USA
| | - David A Ray
- Department of Biological Sciences; Texas Tech University ; Lubbock, TX USA
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When Competing Viruses Unify: Evolution, Conservation, and Plasticity of Genetic Identities. J Mol Evol 2015; 80:305-18. [PMID: 26014757 DOI: 10.1007/s00239-015-9683-y] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Accepted: 05/12/2015] [Indexed: 02/06/2023]
Abstract
In the early 1970s, Manfred Eigen and colleagues developed the quasispecies model (qs) for the population-based origin of RNAs representing the early genetic code. The Eigen idea is basically that a halo of mutants is generated by error-prone replication around the master fittest type which will behave similarly as a biological population. But almost from the start, very interesting and unexpected observations were made regarding competition versus co-operation which suggested more complex interactions. It thus became increasingly clear that although viruses functioned similar to biological species, their behavior was much more complex than the original theory could explain, especially adaptation without changing the consensus involving minority populations. With respect to the origin of natural codes, meaning, and code-use in interactions (communication), it also became clear that individual fittest type-based mechanisms were likewise unable to explain the origin of natural codes such as the genetic code with their context- and consortia-dependence (pragmatic nature). This, instead, required the participation of groups of agents competent in the code and able to edit code because natural codes do not code themselves. Three lines of inquiry, experimental virology, quasispecies theory, and the study of natural codes converged to indicate that consortia of co-operative RNA agents such as viruses must be involved in the fitness of RNA and its involvement in communication, i.e., code-competent interactions. We called this co-operative form quasispecies consortia (qs-c). They are the essential agents that constitute the possibility of evolution of biological group identity. Finally, the basic interactional motifs for the emergence of group identity, communication, and co-operation-together with its opposing functions-are explained by the "Gangen" hypothesis.
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Dhadi SR, Xu Z, Shaik R, Driscoll K, Ramakrishna W. Differential regulation of genes by retrotransposons in rice promoters. PLANT MOLECULAR BIOLOGY 2015; 87:603-13. [PMID: 25697955 DOI: 10.1007/s11103-015-0300-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Accepted: 02/16/2015] [Indexed: 05/06/2023]
Abstract
Rice genome harbors genes and promoters with retrotransposon insertions. There is very little information about their function. The effect of retrotransposon insertions in four rice promoter regions on gene regulation, was investigated using promoter-reporter gene constructs with and without retrotransposons. Differences in expression levels of gus and egfp reporter genes in forward orientation and rfp in reverse orientation were evaluated in rice plants with transient expression employing quantitative RT-PCR analysis, histochemical GUS staining, and eGFP and RFP fluorescent microscopy. The presence of SINE in the promoter 1 (P1) resulted in higher expression levels of the reporter genes, whereas the presence of LINE in P2 or gypsy LTR retrotransposon in P3 reduced expression of the reporter genes. Furthermore, the SINE in P1 acts as an enhancer in contrast with the LINE in P2 and the gypsy LTR retrotransposon in P3 which act as silencers. CTAA and CGG motifs in these retrotransposons are the likely candidates for the downregulation compared to TCTT motif (SINE) which is a candidate for the upregulation of gene expression. The effect of retrotransposons on gene regulation correlated with the earlier investigation of conservation patterns of these four retrotransposon insertions in several rice accessions implying their evolutionary significance.
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Affiliation(s)
- Surendar Reddy Dhadi
- Department of Biological Sciences, Michigan Technological University, Houghton, MI, 49931, USA
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Stapley J, Santure AW, Dennis SR. Transposable elements as agents of rapid adaptation may explain the genetic paradox of invasive species. Mol Ecol 2015; 24:2241-52. [PMID: 25611725 DOI: 10.1111/mec.13089] [Citation(s) in RCA: 126] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Revised: 01/17/2015] [Accepted: 01/19/2015] [Indexed: 12/11/2022]
Abstract
Rapid adaptation of invasive species to novel habitats has puzzled evolutionary biologists for decades, especially as this often occurs in the face of limited genetic variability. Although some ecological traits common to invasive species have been identified, little is known about the possible genomic/genetic mechanisms that may underlie their success. A common scenario in many introductions is that small founder population sizes will often lead to reduced genetic diversity, but that invading populations experience large environmental perturbations, such as changes in habitat and environmental stress. Although sudden and intense stress is usually considered in a negative context, these perturbations may actually facilitate rapid adaptation by affecting genome structure, organization and function via interactions with transposable elements (TEs), especially in populations with low genetic diversity. Stress-induced changes in TE activity can alter gene action and can promote structural variation that may facilitate the rapid adaptation observed in new environments. We focus here on the adaptive potential of TEs in relation to invasive species and highlight their role as powerful mutational forces that can rapidly create genetic diversity. We hypothesize that activity of transposable elements can explain rapid adaptation despite low genetic variation (the genetic paradox of invasive species), and provide a framework under which this hypothesis can be tested using recently developed and emerging genomic technologies.
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Affiliation(s)
- Jessica Stapley
- Department of Animal and Plant Sciences, University of Sheffield, Alfred Denny Building, Western Bank, Sheffield, S10 2TN, UK
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Spadafora C. A LINE-1-encoded reverse transcriptase-dependent regulatory mechanism is active in embryogenesis and tumorigenesis. Ann N Y Acad Sci 2015; 1341:164-71. [PMID: 25586649 DOI: 10.1111/nyas.12637] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
LINE-1 (long interspersed nuclear elements) retrotransposons constitute a large family of retrotransposable elements, accounting for 17% of the human genome. They encode proteins required for their own mobilization, including a reverse transcriptase (RT) enzyme highly expressed in mouse embryos and mouse and human cancer cells and repressed in somatic differentiated healthy cells. We have found that reverse transcription takes place in early murine embryos, yielding an increase in LINE-1 copy number during preimplantation development, which also occurs in tumor progression. RT inhibition irreversibly arrests embryo development, reduces cancer cell proliferation, promotes differentiation, antagonizes tumor growth, and causes a global reprogramming of transcription profiles. These results strongly suggest that a previously unrecognized RT-dependent regulatory mechanism operates during preimplantation development, is repressed during differentiation to normal tissues, and, when erroneously reactivated in adult life, promotes cell transformation and cancer progression by "resurrecting" embryonic transcriptional pathways. The RT-dependent mechanism emerges as a major source of genetic and epigenetic changes with physiological, pathological, and evolutionary implications.
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Affiliation(s)
- Corrado Spadafora
- Istituto Superiore di Sanità, Rome, Italy; CNR Institute of Translational Pharmacology, Rome, Italy
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Lee HE, Ayarpadikannan S, Kim HS. Role of transposable elements in genomic rearrangement, evolution, gene regulation and epigenetics in primates. Genes Genet Syst 2015; 90:245-57. [DOI: 10.1266/ggs.15-00016] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Affiliation(s)
- Hee-Eun Lee
- Department of Biological Sciences, College of Natural Sciences, Pusan National University
- Genetic Engineering Institute, Pusan National University
| | - Selvam Ayarpadikannan
- Department of Biological Sciences, College of Natural Sciences, Pusan National University
| | - Heui-Soo Kim
- Department of Biological Sciences, College of Natural Sciences, Pusan National University
- Genetic Engineering Institute, Pusan National University
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Villarreal LP. Force for ancient and recent life: viral and stem-loop RNA consortia promote life. Ann N Y Acad Sci 2014; 1341:25-34. [PMID: 25376951 DOI: 10.1111/nyas.12565] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Lytic viruses were thought to kill the most numerous host (i.e., kill the winner). But persisting viruses/defectives can also protect against viruses, especially in a ubiquitous virosphere. In 1991, Yarmolinsky et al. discovered the addiction modules of P1 phage, in which opposing toxic and protective functions stabilize persistence. Subsequently, I proposed that lytic and persisting cryptic virus also provide addiction modules that promote group identity. In eukaryotes (and the RNA world), a distinct RNA virus-host relationship exists. Retrovirurses/retroposons are major contributors to eukaryotic genomes. Eukaryotic complexity appears to be mostly mediated by regulatory complexity involving noncoding retroposon-derived RNA. RNA viruses evolve via quasispecies, which contain cooperating, minority, and even opposing RNA types. Quasispecies can also demonstrate group preclusion (e.g., hepatitis C). Stem-loop RNA domains are found in long terminal repeats (and viral RNA) and mediate viral regulation/identity. Thus, stem-loop RNAs may be ancestral regulators. I consider the RNA (ribozyme) world scenario from the perspective of addiction modules and cooperating quasispecies (i.e., subfunctional agents that establish group identity). Such an RNA collective resembles a "gang" but requires the simultaneous emergence of endonuclease, ligase, cooperative catalysis, group identity, and history markers (RNA). I call such a collective a gangen (pathway to gang) needed for life to emerge.
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Affiliation(s)
- Luis P Villarreal
- Center for Virus Research, University of California, Irvine, California
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Sundaram V, Cheng Y, Ma Z, Li D, Xing X, Edge P, Snyder MP, Wang T. Widespread contribution of transposable elements to the innovation of gene regulatory networks. Genome Res 2014; 24:1963-76. [PMID: 25319995 PMCID: PMC4248313 DOI: 10.1101/gr.168872.113] [Citation(s) in RCA: 288] [Impact Index Per Article: 28.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Transposable elements (TEs) have been shown to contain functional binding sites for certain transcription factors (TFs). However, the extent to which TEs contribute to the evolution of TF binding sites is not well known. We comprehensively mapped binding sites for 26 pairs of orthologous TFs in two pairs of human and mouse cell lines (representing two cell lineages), along with epigenomic profiles, including DNA methylation and six histone modifications. Overall, we found that 20% of binding sites were embedded within TEs. This number varied across different TFs, ranging from 2% to 40%. We further identified 710 TF–TE relationships in which genomic copies of a TE subfamily contributed a significant number of binding peaks for a TF, and we found that LTR elements dominated these relationships in human. Importantly, TE-derived binding peaks were strongly associated with open and active chromatin signatures, including reduced DNA methylation and increased enhancer-associated histone marks. On average, 66% of TE-derived binding events were cell type-specific with a cell type-specific epigenetic landscape. Most of the binding sites contributed by TEs were species-specific, but we also identified binding sites conserved between human and mouse, the functional relevance of which was supported by a signature of purifying selection on DNA sequences of these TEs. Interestingly, several TFs had significantly expanded binding site landscapes only in one species, which were linked to species-specific gene functions, suggesting that TEs are an important driving force for regulatory innovation. Taken together, our data suggest that TEs have significantly and continuously shaped gene regulatory networks during mammalian evolution.
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Affiliation(s)
- Vasavi Sundaram
- Department of Genetics, Center for Genome Sciences and Systems Biology, Washington University School of Medicine, St. Louis, Missouri 63108, USA
| | - Yong Cheng
- Department of Genetics, Stanford University, Stanford, California 94305, USA
| | - Zhihai Ma
- Department of Genetics, Stanford University, Stanford, California 94305, USA
| | - Daofeng Li
- Department of Genetics, Center for Genome Sciences and Systems Biology, Washington University School of Medicine, St. Louis, Missouri 63108, USA
| | - Xiaoyun Xing
- Department of Genetics, Center for Genome Sciences and Systems Biology, Washington University School of Medicine, St. Louis, Missouri 63108, USA
| | - Peter Edge
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | - Michael P Snyder
- Department of Genetics, Stanford University, Stanford, California 94305, USA;
| | - Ting Wang
- Department of Genetics, Center for Genome Sciences and Systems Biology, Washington University School of Medicine, St. Louis, Missouri 63108, USA;
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Piacentini L, Fanti L, Specchia V, Bozzetti MP, Berloco M, Palumbo G, Pimpinelli S. Transposons, environmental changes, and heritable induced phenotypic variability. Chromosoma 2014; 123:345-54. [PMID: 24752783 PMCID: PMC4107273 DOI: 10.1007/s00412-014-0464-y] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2014] [Revised: 03/21/2014] [Accepted: 04/07/2014] [Indexed: 12/20/2022]
Abstract
The mechanisms of biological evolution have always been, and still are, the subject of intense debate and modeling. One of the main problems is how the genetic variability is produced and maintained in order to make the organisms adaptable to environmental changes and therefore capable of evolving. In recent years, it has been reported that, in flies and plants, mutations in Hsp90 gene are capable to induce, with a low frequency, many different developmental abnormalities depending on the genetic backgrounds. This has suggested that the reduction of Hsp90 amount makes different development pathways more sensitive to hidden genetic variability. This suggestion revitalized a classical debate around the original Waddington hypothesis of canalization and genetic assimilation making Hsp90 the prototype of morphological capacitor. Other data have also suggested a different mechanism that revitalizes another classic debate about the response of genome to physiological and environmental stress put forward by Barbara McClintock. That data demonstrated that Hsp90 is involved in repression of transposon activity by playing a significant role in piwi-interacting RNA (piRNAs)-dependent RNA interference (RNAi) silencing. The important implication is that the fixed phenotypic abnormalities observed in Hsp90 mutants are probably related to de novo induced mutations by transposon activation. In this case, Hsp90 could be considered as a mutator. In the present theoretical paper, we discuss several possible implications about environmental stress, transposon, and evolution offering also a support to the concept of evolvability.
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Affiliation(s)
- Lucia Piacentini
- Istituto Pasteur, Fondazione Cenci-Bolognetti and Dipartimento Di Biologia e Biotecnologie, Università di Roma “La Sapienza”, Piazzale Aldo Moro 5, 00185 Rome, Italy
| | - Laura Fanti
- Istituto Pasteur, Fondazione Cenci-Bolognetti and Dipartimento Di Biologia e Biotecnologie, Università di Roma “La Sapienza”, Piazzale Aldo Moro 5, 00185 Rome, Italy
| | - Valeria Specchia
- Dipartimento di Scienze e Tecnologie Biologiche ed Ambientali (DiSTeBA), University of Salento, Lecce, Italy
| | - Maria Pia Bozzetti
- Dipartimento di Scienze e Tecnologie Biologiche ed Ambientali (DiSTeBA), University of Salento, Lecce, Italy
| | - Maria Berloco
- Dipartimento di Biologia, Università degli Studi di Bari Aldo Moro, 70121 Bari, Italy
| | - Gino Palumbo
- Dipartimento di Biologia, Università degli Studi di Bari Aldo Moro, 70121 Bari, Italy
| | - Sergio Pimpinelli
- Istituto Pasteur, Fondazione Cenci-Bolognetti and Dipartimento Di Biologia e Biotecnologie, Università di Roma “La Sapienza”, Piazzale Aldo Moro 5, 00185 Rome, Italy
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Grau JH, Poustka AJ, Meixner M, Plötner J. LTR retroelements are intrinsic components of transcriptional networks in frogs. BMC Genomics 2014; 15:626. [PMID: 25056159 PMCID: PMC4131045 DOI: 10.1186/1471-2164-15-626] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Accepted: 07/15/2014] [Indexed: 12/16/2022] Open
Abstract
Background LTR retroelements (LTR REs) constitute a major group of transposable elements widely distributed in eukaryotic genomes. Through their own mechanism of retrotranscription LTR REs enrich the genomic landscape by providing genetic variability, thus contributing to genome structure and organization. Nonetheless, transcriptomic activity of LTR REs still remains an obscure domain within cell, developmental, and organism biology. Results Here we present a first comparative analysis of LTR REs for anuran amphibians based on a full depth coverage transcriptome of the European pool frog, Pelophylax lessonae, the genome of the African clawed frog, Silurana tropicalis (release v7.1), and additional transcriptomes of S. tropicalis and Cyclorana alboguttata. We identified over 1000 copies of LTR REs from all four families (Bel/Pao, Ty1/Copia, Ty3/Gypsy, Retroviridae) in the genome of S. tropicalis and discovered transcripts of several of these elements in all RNA-seq datasets analyzed. Elements of the Ty3/Gypsy family were most active, especially Amn-san elements, which accounted for approximately 0.27% of the genome in Silurana. Some elements exhibited tissue specific expression patterns, for example Hydra1.1 and MuERV-like elements in Pelophylax. In S. tropicalis considerable transcription of LTR REs was observed during embryogenesis as soon as the embryonic genome became activated, i.e. at midblastula transition. In the course of embryonic development the spectrum of transcribed LTR REs changed; during gastrulation and neurulation MuERV-like and SnRV like retroviruses were abundantly transcribed while during organogenesis transcripts of the XEN1 retroviruses became much more active. Conclusions The differential expression of LTR REs during embryogenesis in concert with their tissue-specificity and the protein domains they encode are evidence for the functional roles these elements play as integrative parts of complex regulatory networks. Our results support the meanwhile widely accepted concept that retroelements are not simple “junk DNA” or “harmful genomic parasites” but essential components of the transcriptomic machinery in vertebrates. Electronic supplementary material The online version of this article (doi:10.1186/1471-2164-15-626) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- José Horacio Grau
- Dahlem Center for Genome Research and Medical Systems Biology, Fabeckstraße 60-62, 14195 Berlin, Germany.
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Oliver KR, McComb JA, Greene WK. Transposable elements: powerful contributors to angiosperm evolution and diversity. Genome Biol Evol 2014; 5:1886-901. [PMID: 24065734 PMCID: PMC3814199 DOI: 10.1093/gbe/evt141] [Citation(s) in RCA: 126] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Transposable elements (TEs) are a dominant feature of most flowering plant genomes. Together with other accepted facilitators of evolution, accumulating data indicate that TEs can explain much about their rapid evolution and diversification. Genome size in angiosperms is highly correlated with TE content and the overwhelming bulk (>80%) of large genomes can be composed of TEs. Among retro-TEs, long terminal repeats (LTRs) are abundant, whereas DNA-TEs, which are often less abundant than retro-TEs, are more active. Much adaptive or evolutionary potential in angiosperms is due to the activity of TEs (active TE-Thrust), resulting in an extraordinary array of genetic changes, including gene modifications, duplications, altered expression patterns, and exaptation to create novel genes, with occasional gene disruption. TEs implicated in the earliest origins of the angiosperms include the exapted Mustang, Sleeper, and Fhy3/Far1 gene families. Passive TE-Thrust can create a high degree of adaptive or evolutionary potential by engendering ectopic recombination events resulting in deletions, duplications, and karyotypic changes. TE activity can also alter epigenetic patterning, including that governing endosperm development, thus promoting reproductive isolation. Continuing evolution of long-lived resprouter angiosperms, together with genetic variation in their multiple meristems, indicates that TEs can facilitate somatic evolution in addition to germ line evolution. Critical to their success, angiosperms have a high frequency of polyploidy and hybridization, with resultant increased TE activity and introgression, and beneficial gene duplication. Together with traditional explanations, the enhanced genomic plasticity facilitated by TE-Thrust, suggests a more complete and satisfactory explanation for Darwin's "abominable mystery": the spectacular success of the angiosperms.
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Affiliation(s)
- Keith R Oliver
- School of Veterinary and Life Sciences, Murdoch University, Perth, Western Australia, Australia
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