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Lanciano S, Philippe C, Sarkar A, Pratella D, Domrane C, Doucet AJ, van Essen D, Saccani S, Ferry L, Defossez PA, Cristofari G. Locus-level L1 DNA methylation profiling reveals the epigenetic and transcriptional interplay between L1s and their integration sites. CELL GENOMICS 2024; 4:100498. [PMID: 38309261 PMCID: PMC10879037 DOI: 10.1016/j.xgen.2024.100498] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Revised: 07/20/2023] [Accepted: 01/09/2024] [Indexed: 02/05/2024]
Abstract
Long interspersed element 1 (L1) retrotransposons are implicated in human disease and evolution. Their global activity is repressed by DNA methylation, but deciphering the regulation of individual copies has been challenging. Here, we combine short- and long-read sequencing to unveil L1 methylation heterogeneity across cell types, families, and individual loci and elucidate key principles involved. We find that the youngest primate L1 families are specifically hypomethylated in pluripotent stem cells and the placenta but not in most tumors. Locally, intronic L1 methylation is intimately associated with gene transcription. Conversely, the L1 methylation state can propagate to the proximal region up to 300 bp. This phenomenon is accompanied by the binding of specific transcription factors, which drive the expression of L1 and chimeric transcripts. Finally, L1 hypomethylation alone is typically insufficient to trigger L1 expression due to redundant silencing pathways. Our results illuminate the epigenetic and transcriptional interplay between retrotransposons and their host genome.
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Affiliation(s)
- Sophie Lanciano
- University Cote d'Azur, INSERM, CNRS, Institute for Research on Cancer and Aging of Nice (IRCAN), Nice, France
| | - Claude Philippe
- University Cote d'Azur, INSERM, CNRS, Institute for Research on Cancer and Aging of Nice (IRCAN), Nice, France
| | - Arpita Sarkar
- University Cote d'Azur, INSERM, CNRS, Institute for Research on Cancer and Aging of Nice (IRCAN), Nice, France
| | - David Pratella
- University Cote d'Azur, INSERM, CNRS, Institute for Research on Cancer and Aging of Nice (IRCAN), Nice, France
| | - Cécilia Domrane
- University Paris Cité, CNRS, Epigenetics and Cell Fate, Paris, France
| | - Aurélien J Doucet
- University Cote d'Azur, INSERM, CNRS, Institute for Research on Cancer and Aging of Nice (IRCAN), Nice, France
| | - Dominic van Essen
- University Cote d'Azur, INSERM, CNRS, Institute for Research on Cancer and Aging of Nice (IRCAN), Nice, France
| | - Simona Saccani
- University Cote d'Azur, INSERM, CNRS, Institute for Research on Cancer and Aging of Nice (IRCAN), Nice, France
| | - Laure Ferry
- University Paris Cité, CNRS, Epigenetics and Cell Fate, Paris, France
| | | | - Gael Cristofari
- University Cote d'Azur, INSERM, CNRS, Institute for Research on Cancer and Aging of Nice (IRCAN), Nice, France.
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2
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Yang L, Metzger GA, Padilla Del Valle R, Delgadillo Rubalcaba D, McLaughlin RN. Evolutionary insights from profiling LINE-1 activity at allelic resolution in a single human genome. EMBO J 2024; 43:112-131. [PMID: 38177314 PMCID: PMC10883270 DOI: 10.1038/s44318-023-00007-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2023] [Revised: 10/18/2023] [Accepted: 11/10/2023] [Indexed: 01/06/2024] Open
Abstract
Transposable elements have created the majority of the sequence in many genomes. In mammals, LINE-1 retrotransposons have been expanding for more than 100 million years as distinct, consecutive lineages; however, the drivers of this recurrent lineage emergence and disappearance are unknown. Most human genome assemblies provide a record of this ancient evolution, but fail to resolve ongoing LINE-1 retrotranspositions. Utilizing the human CHM1 long-read-based haploid assembly, we identified and cloned all full-length, intact LINE-1s, and found 29 LINE-1s with measurable in vitro retrotransposition activity. Among individuals, these LINE-1s varied in their presence, their allelic sequences, and their activity. We found that recently retrotransposed LINE-1s tend to be active in vitro and polymorphic in the population relative to more ancient LINE-1s. However, some rare allelic forms of old LINE-1s retain activity, suggesting older lineages can persist longer than expected. Finally, in LINE-1s with in vitro activity and in vivo fitness, we identified mutations that may have increased replication in ancient genomes and may prove promising candidates for mechanistic investigations of the drivers of LINE-1 evolution and which LINE-1 sequences contribute to human disease.
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Affiliation(s)
- Lei Yang
- Pacific Northwest Research Institute, Seattle, WA, USA
| | | | - Ricky Padilla Del Valle
- Pacific Northwest Research Institute, Seattle, WA, USA
- Molecular and Cellular Biology Graduate Program, University of Washington, Seattle, WA, USA
| | | | - Richard N McLaughlin
- Pacific Northwest Research Institute, Seattle, WA, USA.
- Molecular and Cellular Biology Graduate Program, University of Washington, Seattle, WA, USA.
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3
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Alkailani MI, Gibbings D. The Regulation and Immune Signature of Retrotransposons in Cancer. Cancers (Basel) 2023; 15:4340. [PMID: 37686616 PMCID: PMC10486412 DOI: 10.3390/cancers15174340] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2023] [Revised: 08/14/2023] [Accepted: 08/18/2023] [Indexed: 09/10/2023] Open
Abstract
Advances in sequencing technologies and the bioinformatic analysis of big data facilitate the study of jumping genes' activity in the human genome in cancer from a broad perspective. Retrotransposons, which move from one genomic site to another by a copy-and-paste mechanism, are regulated by various molecular pathways that may be disrupted during tumorigenesis. Active retrotransposons can stimulate type I IFN responses. Although accumulated evidence suggests that retrotransposons can induce inflammation, the research investigating the exact mechanism of triggering these responses is ongoing. Understanding these mechanisms could improve the therapeutic management of cancer through the use of retrotransposon-induced inflammation as a tool to instigate immune responses to tumors.
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Affiliation(s)
- Maisa I. Alkailani
- College of Health and Life Sciences, Hamad Bin Khalifa University, Qatar Foundation, Doha P.O. Box 34110, Qatar
| | - Derrick Gibbings
- Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada;
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4
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Dumas F, Perelman PL, Biltueva L, Roelke-Parker ME. Retrotransposon mapping in spider monkey genomes of the family Atelidae (Platyrrhini, Primates) shows a high level of LINE-1 amplification. JOURNAL OF BIOLOGICAL RESEARCH - BOLLETTINO DELLA SOCIETÀ ITALIANA DI BIOLOGIA SPERIMENTALE 2022. [DOI: 10.4081/jbr.2022.10725] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
To investigate the distribution of LINE-1 repeat sequences, a LINE-1 probe was Fluorescence In Situ Hybridized (FISH) on the chromosomes of Ateles geoffroyi and Ateles fusciceps (Atelidae); a LINE-1 probe was also mapped on Cebuella pygmaea (Cebidae) and used as an outgroup for phylogenetic comparison. Ateles spider monkeys have a highly rearranged genome and are an ideal model for testing whether LINE-1 is involved in genome evolution. The LINE-1 probe has been mapped in the two Atelidae species for the first time, revealing a high accumulation of LINE-1 sequences along chromosomal arms, including telomeres, and a scarcity of LINE-1 signals at centromere positions. LINE-1 mapping in C. pygmaea (Cebidae) revealed signals at centromere positions and along chromosome arms, which was consistent with previous published data from other Cebidae species. In a broader sense, the results were analyzed in light of published data on whole-chromosomal human probes mapped in these genomes. This analysis allows us to speculate about the presence of LINE-1 sequences at the junction of human chromosomal syntenies, as well as a possible link between these sequences and chromosomal rearrangements.
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5
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Stow EC, Baddoo M, LaRosa AJ, LaCoste D, Deininger P, Belancio V. SCIFER: approach for analysis of LINE-1 mRNA expression in single cells at a single locus resolution. Mob DNA 2022; 13:21. [PMID: 36028901 PMCID: PMC9413895 DOI: 10.1186/s13100-022-00276-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Accepted: 08/09/2022] [Indexed: 12/03/2022] Open
Abstract
BACKGROUND Endogenous expression of L1 mRNA is the first step in an L1-initiated mutagenesis event. However, the contribution of individual cell types to patterns of organ-specific L1 mRNA expression remains poorly understood, especially at single-locus resolution. We introduce a method to quantify expression of mobile elements at the single-locus resolution in scRNA-Seq datasets called Single Cell Implementation to Find Expressed Retrotransposons (SCIFER). SCIFER aligns scRNA-Seq reads uniquely to the genome and extracts alignments from single cells by cell-specific barcodes. In contrast to the alignment performed using default parameters, this alignment strategy increases accuracy of L1 locus identification by retaining only reads that are uniquely mapped to individual L1 loci. L1 loci expressed in single cells are unambiguously identified using a list of L1 loci manually validated to be expressed in bulk RNA-Seq datasets generated from the same cell line or organ. RESULTS Validation of SCIFER using MCF7 cells determined technical parameters needed for optimal detection of L1 expression in single cells. We show that unsupervised analysis of L1 expression in single cells exponentially inflates both the levels of L1 expression and the number of expressed L1 loci. Application of SCIFER to analysis of scRNA-Seq datasets generated from mouse and human testes identified that mouse Round Spermatids and human Spermatogonia, Spermatocytes, and Round Spermatids express the highest levels of L1 mRNA. Our analysis also determined that similar to mice, human testes from unrelated individuals share as much as 80% of expressed L1 loci. Additionally, SCIFER determined that individual mouse cells co-express different L1 sub-families and different families of transposable elements, experimentally validating their co-existence in the same cell. CONCLUSIONS SCIFER detects mRNA expression of individual L1 loci in single cells. It is compatible with scRNA-Seq datasets prepared using traditional sequencing methods. Validated using a human cancer cell line, SCIFER analysis of mouse and human testes identified key cell types supporting L1 expression in these species. This will further our understanding of differences and similarities in endogenous L1 mRNA expression patterns in mice and humans.
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Affiliation(s)
- Emily C Stow
- Tulane Cancer Center, Tulane Health Sciences Center, 1700 Tulane Ave, New Orleans, LA, 70112, USA
- Department of Structural and Cellular Biology, Tulane School of Medicine, 1430 Tulane Ave, New Orleans, 70112, USA
| | - Melody Baddoo
- Tulane Cancer Center, Tulane Health Sciences Center, 1700 Tulane Ave, New Orleans, LA, 70112, USA
- Department of Structural and Cellular Biology, Tulane School of Medicine, 1430 Tulane Ave, New Orleans, 70112, USA
| | - Alexis J LaRosa
- Tulane Cancer Center, Tulane Health Sciences Center, 1700 Tulane Ave, New Orleans, LA, 70112, USA
- Department of Structural and Cellular Biology, Tulane School of Medicine, 1430 Tulane Ave, New Orleans, 70112, USA
| | - Dawn LaCoste
- Tulane Cancer Center, Tulane Health Sciences Center, 1700 Tulane Ave, New Orleans, LA, 70112, USA
- Department of Structural and Cellular Biology, Tulane School of Medicine, 1430 Tulane Ave, New Orleans, 70112, USA
| | - Prescott Deininger
- Tulane Cancer Center, Tulane Health Sciences Center, 1700 Tulane Ave, New Orleans, LA, 70112, USA
- Department of Epidemiology, Tulane School of Public Health and Tropical Medicine, New Orleans, LA, 70112, USA
| | - Victoria Belancio
- Tulane Cancer Center, Tulane Health Sciences Center, 1700 Tulane Ave, New Orleans, LA, 70112, USA.
- Department of Structural and Cellular Biology, Tulane School of Medicine, 1430 Tulane Ave, New Orleans, 70112, USA.
- Department of Epidemiology, Tulane School of Public Health and Tropical Medicine, New Orleans, LA, 70112, USA.
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6
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Billon V, Sanchez-Luque FJ, Rasmussen J, Bodea GO, Gerhardt DJ, Gerdes P, Cheetham SW, Schauer SN, Ajjikuttira P, Meyer TJ, Layman CE, Nevonen KA, Jansz N, Garcia-Perez JL, Richardson SR, Ewing AD, Carbone L, Faulkner GJ. Somatic retrotransposition in the developing rhesus macaque brain. Genome Res 2022; 32:1298-1314. [PMID: 35728967 PMCID: PMC9341517 DOI: 10.1101/gr.276451.121] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Accepted: 06/14/2022] [Indexed: 12/03/2022]
Abstract
The retrotransposon LINE-1 (L1) is central to the recent evolutionary history of the human genome and continues to drive genetic diversity and germline pathogenesis. However, the spatiotemporal extent and biological significance of somatic L1 activity are poorly defined and are virtually unexplored in other primates. From a single L1 lineage active at the divergence of apes and Old World monkeys, successive L1 subfamilies have emerged in each descendant primate germline. As revealed by case studies, the presently active human L1 subfamily can also mobilize during embryonic and brain development in vivo. It is unknown whether nonhuman primate L1s can similarly generate somatic insertions in the brain. Here we applied approximately 40× single-cell whole-genome sequencing (scWGS), as well as retrotransposon capture sequencing (RC-seq), to 20 hippocampal neurons from two rhesus macaques (Macaca mulatta). In one animal, we detected and PCR-validated a somatic L1 insertion that generated target site duplications, carried a short 5' transduction, and was present in ∼7% of hippocampal neurons but absent from cerebellum and nonbrain tissues. The corresponding donor L1 allele was exceptionally mobile in vitro and was embedded in PRDM4, a gene expressed throughout development and in neural stem cells. Nanopore long-read methylome and RNA-seq transcriptome analyses indicated young retrotransposon subfamily activation in the early embryo, followed by repression in adult tissues. These data highlight endogenous macaque L1 retrotransposition potential, provide prototypical evidence of L1-mediated somatic mosaicism in a nonhuman primate, and allude to L1 mobility in the brain over the past 30 million years of human evolution.
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Affiliation(s)
- Victor Billon
- Queensland Brain Institute, University of Queensland, St. Lucia, Queensland 4067, Australia
- Biology Department, École Normale Supérieure Paris-Saclay, 91190 Gif-sur-Yvette, France
| | - Francisco J Sanchez-Luque
- GENYO. Pfizer-University of Granada-Andalusian Government Centre for Genomics and Oncological Research, PTS Granada 18016, Spain
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of Edinburgh, Western General Hospital, Edinburgh EH4 2XU, United Kingdom
- Institute of Parasitology and Biomedicine "Lopez-Neyra"-Spanish National Research Council, PTS Granada 18016, Spain
| | - Jay Rasmussen
- Queensland Brain Institute, University of Queensland, St. Lucia, Queensland 4067, Australia
| | - Gabriela O Bodea
- Queensland Brain Institute, University of Queensland, St. Lucia, Queensland 4067, Australia
- Mater Research Institute-University of Queensland, Woolloongabba, Queensland 4102, Australia
| | - Daniel J Gerhardt
- Mater Research Institute-University of Queensland, Woolloongabba, Queensland 4102, Australia
| | - Patricia Gerdes
- Mater Research Institute-University of Queensland, Woolloongabba, Queensland 4102, Australia
| | - Seth W Cheetham
- Mater Research Institute-University of Queensland, Woolloongabba, Queensland 4102, Australia
| | - Stephanie N Schauer
- Mater Research Institute-University of Queensland, Woolloongabba, Queensland 4102, Australia
| | - Prabha Ajjikuttira
- Queensland Brain Institute, University of Queensland, St. Lucia, Queensland 4067, Australia
| | - Thomas J Meyer
- Division of Genetics, Oregon National Primate Research Center, Beaverton, Oregon 97006, USA
| | - Cora E Layman
- Department of Medicine, Knight Cardiovascular Institute, Oregon Health and Science University, Portland, Oregon 97239, USA
| | - Kimberly A Nevonen
- Department of Medicine, Knight Cardiovascular Institute, Oregon Health and Science University, Portland, Oregon 97239, USA
| | - Natasha Jansz
- Mater Research Institute-University of Queensland, Woolloongabba, Queensland 4102, Australia
| | - Jose L Garcia-Perez
- GENYO. Pfizer-University of Granada-Andalusian Government Centre for Genomics and Oncological Research, PTS Granada 18016, Spain
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of Edinburgh, Western General Hospital, Edinburgh EH4 2XU, United Kingdom
| | - Sandra R Richardson
- Mater Research Institute-University of Queensland, Woolloongabba, Queensland 4102, Australia
| | - Adam D Ewing
- Mater Research Institute-University of Queensland, Woolloongabba, Queensland 4102, Australia
| | - Lucia Carbone
- Division of Genetics, Oregon National Primate Research Center, Beaverton, Oregon 97006, USA
- Department of Medicine, Knight Cardiovascular Institute, Oregon Health and Science University, Portland, Oregon 97239, USA
- Department of Molecular and Medical Genetics, Oregon Health and Science University, Portland, Oregon 97239, USA
- Department of Medical Informatics and Clinical Epidemiology, Oregon Health and Science University, Portland, Oregon 97239, USA
| | - Geoffrey J Faulkner
- Queensland Brain Institute, University of Queensland, St. Lucia, Queensland 4067, Australia
- Mater Research Institute-University of Queensland, Woolloongabba, Queensland 4102, Australia
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7
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A retrotransposon storm marks clinical phenoconversion to late-onset Alzheimer's disease. GeroScience 2022; 44:1525-1550. [PMID: 35585302 PMCID: PMC9213607 DOI: 10.1007/s11357-022-00580-w] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Accepted: 04/26/2022] [Indexed: 12/03/2022] Open
Abstract
Recent reports have suggested that the reactivation of otherwise transcriptionally silent transposable elements (TEs) might induce brain degeneration, either by dysregulating the expression of genes and pathways implicated in cognitive decline and dementia or through the induction of immune-mediated neuroinflammation resulting in the elimination of neural and glial cells. In the work we present here, we test the hypothesis that differentially expressed TEs in blood could be used as biomarkers of cognitive decline and development of AD. To this aim, we used a sample of aging subjects (age > 70) that developed late-onset Alzheimer’s disease (LOAD) over a relatively short period of time (12–48 months), for which blood was available before and after their phenoconversion, and a group of cognitive stable subjects as controls. We applied our developed and validated customized pipeline that allows the identification, characterization, and quantification of the differentially expressed (DE) TEs before and after the onset of manifest LOAD, through analyses of RNA-Seq data. We compared the level of DE TEs within more than 600,000 TE-mapping RNA transcripts from 25 individuals, whose specimens we obtained before and after their phenotypic conversion (phenoconversion) to LOAD, and discovered that 1790 TE transcripts showed significant expression differences between these two timepoints (logFC ± 1.5, logCMP > 5.3, nominal p value < 0.01). These DE transcripts mapped both over- and under-expressed TE elements. Occurring before the clinical phenoconversion, this TE storm features significant increases in DE transcripts of LINEs, LTRs, and SVAs, while those for SINEs are significantly depleted. These dysregulations end with signs of manifest LOAD. This set of highly DE transcripts generates a TE transcriptional profile that accurately discriminates the before and after phenoconversion states of these subjects. Our findings suggest that a storm of DE TEs occurs before phenoconversion from normal cognition to manifest LOAD in risk individuals compared to controls, and may provide useful blood-based biomarkers for heralding such a clinical transition, also suggesting that TEs can indeed participate in the complex process of neurodegeneration.
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8
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Campitelli LF, Yellan I, Albu M, Barazandeh M, Patel ZM, Blanchette M, Hughes TR. Reconstruction of full-length LINE-1 progenitors from ancestral genomes. Genetics 2022; 221:6584822. [PMID: 35552404 PMCID: PMC9252281 DOI: 10.1093/genetics/iyac074] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Accepted: 04/27/2022] [Indexed: 11/24/2022] Open
Abstract
Sequences derived from the Long INterspersed Element-1 (L1) family of retrotransposons occupy at least 17% of the human genome, with 67 distinct subfamilies representing successive waves of expansion and extinction in mammalian lineages. L1s contribute extensively to gene regulation, but their molecular history is difficult to trace, because most are present only as truncated and highly mutated fossils. Consequently, L1 entries in current databases of repeat sequences are composed mainly of short diagnostic subsequences, rather than full functional progenitor sequences for each subfamily. Here, we have coupled 2 levels of sequence reconstruction (at the level of whole genomes and L1 subfamilies) to reconstruct progenitor sequences for all human L1 subfamilies that are more functionally and phylogenetically plausible than existing models. Most of the reconstructed sequences are at or near the canonical length of L1s and encode uninterrupted ORFs with expected protein domains. We also show that the presence or absence of binding sites for KRAB-C2H2 Zinc Finger Proteins, even in ancient-reconstructed progenitor L1s, mirrors binding observed in human ChIP-exo experiments, thus extending the arms race and domestication model. RepeatMasker searches of the modern human genome suggest that the new models may be able to assign subfamily resolution identities to previously ambiguous L1 instances. The reconstructed L1 sequences will be useful for genome annotation and functional study of both L1 evolution and L1 contributions to host regulatory networks.
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Affiliation(s)
- Laura F Campitelli
- Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A1, Canada.,Donnelly Centre, University of Toronto, Toronto, ON M5S 1A1, Canada
| | - Isaac Yellan
- Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A1, Canada.,Donnelly Centre, University of Toronto, Toronto, ON M5S 1A1, Canada
| | - Mihai Albu
- Donnelly Centre, University of Toronto, Toronto, ON M5S 1A1, Canada
| | - Marjan Barazandeh
- Donnelly Centre, University of Toronto, Toronto, ON M5S 1A1, Canada.,Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Zain M Patel
- Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A1, Canada.,Donnelly Centre, University of Toronto, Toronto, ON M5S 1A1, Canada
| | - Mathieu Blanchette
- Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, BC V6T 1Z4, Canada.,Department of Computer Science, McGill University, Montreal, Quebec H3A 0G4, Canada
| | - Timothy R Hughes
- Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A1, Canada.,Donnelly Centre, University of Toronto, Toronto, ON M5S 1A1, Canada
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9
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Dazenière J, Bousios A, Eyre-Walker A. Patterns of selection in the evolution of a transposable element. G3 GENES|GENOMES|GENETICS 2022; 12:6545286. [PMID: 35262706 PMCID: PMC9073684 DOI: 10.1093/g3journal/jkac056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Accepted: 02/14/2022] [Indexed: 11/23/2022]
Abstract
Transposable elements are a major component of most eukaryotic genomes. Here, we present a new approach which allows us to study patterns of natural selection in the evolution of transposable elements over short time scales. The method uses the alignment of all elements with intact gag/pol genes of a transposable element family from a single genome. We predict that the ratio of nonsynonymous to synonymous variants in the alignment should decrease as a function of the frequency of the variants, because elements with nonsynonymous variants that reduce transposition will have fewer progeny. We apply our method to Sirevirus long-terminal repeat retrotransposons that are abundant in maize and other plant species and show that nonsynonymous to synonymous variants declines as variant frequency increases, indicating that negative selection is acting strongly on the Sirevirus genome. The asymptotic value of nonsynonymous to synonymous variants suggests that at least 85% of all nonsynonymous mutations in the transposable element reduce transposition. Crucially, these patterns in nonsynonymous to synonymous variants are only predicted to occur if the gene products from a particular transposable element insertion preferentially promote the transposition of the same insertion. Overall, by using large numbers of intact elements, this study sheds new light on the selective processes that act on transposable elements.
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Affiliation(s)
- Julie Dazenière
- School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9RH, UK
| | - Alexandros Bousios
- School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9RH, UK
| | - Adam Eyre-Walker
- School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9RH, UK
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10
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On the Base Composition of Transposable Elements. Int J Mol Sci 2022; 23:ijms23094755. [PMID: 35563146 PMCID: PMC9099904 DOI: 10.3390/ijms23094755] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Revised: 04/22/2022] [Accepted: 04/23/2022] [Indexed: 01/27/2023] Open
Abstract
Transposable elements exhibit a base composition that is often different from the genomic average and from hosts’ genes. The most common compositional bias is towards Adenosine and Thymine, although this bias is not universal, and elements with drastically different base composition can coexist within the same genome. The AT-richness of transposable elements is apparently maladaptive because it results in poor transcription and sub-optimal translation of proteins encoded by the elements. The cause(s) of this unusual base composition remain unclear and have yet to be investigated. Here, I review what is known about the nucleotide content of transposable elements and how this content can affect the genome of their host as well as their own replication. The compositional bias of transposable elements could result from several non-exclusive processes including horizontal transfer, mutational bias, and selection. It appears that mutation alone cannot explain the high AT-content of transposons and that selection plays a major role in the evolution of the compositional bias. The reason why selection would favor a maladaptive nucleotide content remains however unexplained and is an area of investigation that clearly deserves attention.
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11
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Freeman B, White T, Kaul T, Stow EC, Baddoo M, Ungerleider N, Morales M, Yang H, Deharo D, Deininger P, Belancio V. Analysis of epigenetic features characteristic of L1 loci expressed in human cells. Nucleic Acids Res 2022; 50:1888-1907. [PMID: 35100410 PMCID: PMC8887483 DOI: 10.1093/nar/gkac013] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Revised: 12/27/2021] [Accepted: 01/24/2022] [Indexed: 12/26/2022] Open
Abstract
Only a select few L1 loci in the human genome are expressed in any given cell line or organ, likely to minimize damage done to the genome. The epigenetic features and requirements of expressed L1 loci are currently unknown. Using human cells and comprehensive epigenetic analysis of individual expressed and unexpressed L1 loci, we determined that endogenous L1 transcription depends on a combination of epigenetic factors, including open chromatin, activating histone modifications, and hypomethylation at the L1 promoter. We demonstrate that the L1 promoter seems to require interaction with enhancer elements for optimal function. We utilize epigenetic context to predict the expression status of L1Hs loci that are poorly mappable with RNA-Seq. Our analysis identified a population of ‘transitional’ L1 loci that likely have greater potential to be activated during the epigenetic dysregulation seen in tumors and during aging because they are the most responsive to targeted CRISPR-mediated delivery of trans-activating domains. We demonstrate that an engineered increase in endogenous L1 mRNA expression increases Alu mobilization. Overall, our findings present the first global and comprehensive analysis of epigenetic status of individual L1 loci based on their expression status and demonstrate the importance of epigenetic context for L1 expression heterogeneity.
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Affiliation(s)
- Benjamin Freeman
- Department of Structural and Cellular Biology, Tulane University School of Medicine, Tulane Cancer Center, Tulane Center for Aging, New Orleans, LA 70112, USA
- Tulane Cancer Center, Tulane Health Sciences Center, 1700 Tulane Ave, New Orleans, LA 70112, USA
| | - Travis White
- Sloan Kettering Institute for Cancer Research, NY, NY 10065, USA
| | - Tiffany Kaul
- Tulane Cancer Center, Tulane Health Sciences Center, 1700 Tulane Ave, New Orleans, LA 70112, USA
| | - Emily C Stow
- Department of Structural and Cellular Biology, Tulane University School of Medicine, Tulane Cancer Center, Tulane Center for Aging, New Orleans, LA 70112, USA
- Tulane Cancer Center, Tulane Health Sciences Center, 1700 Tulane Ave, New Orleans, LA 70112, USA
| | - Melody Baddoo
- Department of Pathology, Tulane University School of Medicine, Tulane Cancer Center, New Orleans, LA 70112, USA
| | - Nathan Ungerleider
- Department of Pathology, Tulane University School of Medicine, Tulane Cancer Center, New Orleans, LA 70112, USA
| | - Maria Morales
- Tulane Cancer Center, Tulane Health Sciences Center, 1700 Tulane Ave, New Orleans, LA 70112, USA
| | - Hanlin Yang
- Tulane Cancer Center, Tulane Health Sciences Center, 1700 Tulane Ave, New Orleans, LA 70112, USA
| | - Dawn Deharo
- Department of Structural and Cellular Biology, Tulane University School of Medicine, Tulane Cancer Center, Tulane Center for Aging, New Orleans, LA 70112, USA
- Tulane Cancer Center, Tulane Health Sciences Center, 1700 Tulane Ave, New Orleans, LA 70112, USA
| | - Prescott Deininger
- Tulane Cancer Center, Tulane Health Sciences Center, 1700 Tulane Ave, New Orleans, LA 70112, USA
- Department of Epidemiology, Tulane School of Public Health and Tropical Medicine, New Orleans, LA 70112, USA
| | - Victoria P Belancio
- To whom correspondence should be addressed. Tel: +1 504 988 4506; Fax: +1 504 988 1687;
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12
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Ceraulo S, Perelman PL, Dumas F. Massive LINE‐1 retrotransposon enrichment in tamarins of the Cebidae family (Platyrrhini, Primates) and its significance for genome evolution. J ZOOL SYST EVOL RES 2021. [DOI: 10.1111/jzs.12536] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Simona Ceraulo
- Department of “Scienze e Tecnologie Biologiche, Chimiche e Farmaceutiche (STEBICEF)” University of Palermo Palermo Italy
| | | | - Francesca Dumas
- Department of “Scienze e Tecnologie Biologiche, Chimiche e Farmaceutiche (STEBICEF)” University of Palermo Palermo Italy
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13
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Jiang JC, Rothnagel JA, Upton KR. Widespread Exaptation of L1 Transposons for Transcription Factor Binding in Breast Cancer. Int J Mol Sci 2021; 22:5625. [PMID: 34070697 PMCID: PMC8199441 DOI: 10.3390/ijms22115625] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 05/18/2021] [Accepted: 05/20/2021] [Indexed: 12/29/2022] Open
Abstract
L1 transposons occupy 17% of the human genome and are widely exapted for the regulation of human genes, particularly in breast cancer, where we have previously shown abundant cancer-specific transcription factor (TF) binding sites within the L1PA2 subfamily. In the current study, we performed a comprehensive analysis of TF binding activities in primate-specific L1 subfamilies and identified pervasive exaptation events amongst these evolutionarily related L1 transposons. By motif scanning, we predicted diverse and abundant TF binding potentials within the L1 transposons. We confirmed substantial TF binding activities in the L1 subfamilies using TF binding sites consolidated from an extensive collection of publicly available ChIP-seq datasets. Young L1 subfamilies (L1HS, L1PA2 and L1PA3) contributed abundant TF binding sites in MCF7 cells, primarily via their 5' UTR. This is expected as the L1 5' UTR hosts cis-regulatory elements that are crucial for L1 replication and mobilisation. Interestingly, the ancient L1 subfamilies, where 5' truncation was common, displayed comparable TF binding capacity through their 3' ends, suggesting an alternative exaptation mechanism in L1 transposons that was previously unnoticed. Overall, primate-specific L1 transposons were extensively exapted for TF binding in MCF7 breast cancer cells and are likely prominent genetic players modulating breast cancer transcriptional regulation.
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Affiliation(s)
| | | | - Kyle R. Upton
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, QLD 4072, Australia; (J.-C.J.); (J.A.R.)
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14
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Jiang JC, Rothnagel JA, Upton KR. Integrated transcription factor profiling with transcriptome analysis identifies L1PA2 transposons as global regulatory modulators in a breast cancer model. Sci Rep 2021; 11:8083. [PMID: 33850167 PMCID: PMC8044218 DOI: 10.1038/s41598-021-86395-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Accepted: 02/26/2021] [Indexed: 12/13/2022] Open
Abstract
While transposons are generally silenced in somatic tissues, many transposons escape epigenetic repression in epithelial cancers, become transcriptionally active and contribute to the regulation of human gene expression. We have developed a bioinformatic pipeline for the integrated analysis of transcription factor binding and transcriptomic data to identify transposon-derived promoters that are activated in specific diseases and developmental states. We applied this pipeline to a breast cancer model, and found that the L1PA2 transposon subfamily contributes abundant regulatory sequences to co-ordinated transcriptional regulation in breast cancer. Transcription factor profiling demonstrates that over 27% of L1PA2 transposons harbour co-localised binding sites of functionally interacting, cancer-associated transcription factors in MCF7 cells, a cell line used to model breast cancer. Transcriptomic analysis reveals that L1PA2 transposons also contribute transcription start sites to up-regulated transcripts in MCF7 cells, including some transcripts with established oncogenic properties. In addition, we verified the utility of our pipeline on other transposon subfamilies, as well as on leukemia and lung carcinoma cell lines. We demonstrate that the normally quiescent regulatory activities of transposons can be activated and alter the cancer transcriptome. In particular, the L1PA2 subfamily contributes abundant regulatory sequences, and likely plays a global role in modulating breast cancer transcriptional regulation. Understanding the regulatory impact of L1PA2 on breast cancer genomes provides additional insights into cancer genome regulation, and may provide novel biomarkers for disease diagnosis, prognosis and therapy.
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Affiliation(s)
- Jiayue-Clara Jiang
- School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, QLD, 4072, Australia
| | - Joseph A Rothnagel
- School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, QLD, 4072, Australia
| | - Kyle R Upton
- School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, QLD, 4072, Australia.
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15
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Furano AV, Jones CE, Periwal V, Callahan KE, Walser JC, Cook PR. Cryptic genetic variation enhances primate L1 retrotransposon survival by enlarging the functional coiled coil sequence space of ORF1p. PLoS Genet 2020; 16:e1008991. [PMID: 32797042 PMCID: PMC7449397 DOI: 10.1371/journal.pgen.1008991] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 08/26/2020] [Accepted: 07/13/2020] [Indexed: 11/18/2022] Open
Abstract
Accounting for continual evolution of deleterious L1 retrotransposon families, which can contain hundreds to thousands of members remains a major issue in mammalian biology. L1 activity generated upwards of 40% of some mammalian genomes, including humans where they remain active, causing genetic defects and rearrangements. L1 encodes a coiled coil-containing protein that is essential for retrotransposition, and the emergence of novel primate L1 families has been correlated with episodes of extensive amino acid substitutions in the coiled coil. These results were interpreted as an adaptive response to maintain L1 activity, however its mechanism remained unknown. Although an adventitious mutation can inactivate coiled coil function, its effect could be buffered by epistatic interactions within the coiled coil, made more likely if the family contains a diverse set of coiled coil sequences-collectively referred to as the coiled coil sequence space. Amino acid substitutions that do not affect coiled coil function (i.e., its phenotype) could be "hidden" from (not subject to) purifying selection. The accumulation of such substitutions, often referred to as cryptic genetic variation, has been documented in various proteins. Here we report that this phenomenon was in effect during the latest episode of primate coiled coil evolution, which occurred 30-10 MYA during the emergence of primate L1Pa7-L1Pa3 families. First, we experimentally demonstrated that while coiled coil function (measured by retrotransposition) can be eliminated by single epistatic mutations, it nonetheless can also withstand extensive amino acid substitutions. Second, principal component and cluster analysis showed that the coiled coil sequence space of each of the L1Pa7-3 families was notably increased by the presence of distinct, coexisting coiled coil sequences. Thus, sampling related networks of functional sequences rather than traversing discrete adaptive states characterized the persistence L1 activity during this evolutionary event.
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Affiliation(s)
- Anthony V. Furano
- Laboratory of Cellular and Molecular Biology, NIDDK, National Institutes of Health, Bethesda, Maryland, United States of America
- * E-mail:
| | - Charlie E. Jones
- Laboratory of Cellular and Molecular Biology, NIDDK, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Vipul Periwal
- Laboratory of Biological Modeling, NIDDK, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Kathryn E. Callahan
- Laboratory of Cellular and Molecular Biology, NIDDK, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Jean-Claude Walser
- Laboratory of Cellular and Molecular Biology, NIDDK, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Pamela R. Cook
- Laboratory of Cellular and Molecular Biology, NIDDK, National Institutes of Health, Bethesda, Maryland, United States of America
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16
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Ruggiero RP, Boissinot S. Variation in base composition underlies functional and evolutionary divergence in non-LTR retrotransposons. Mob DNA 2020; 11:14. [PMID: 32280379 PMCID: PMC7140322 DOI: 10.1186/s13100-020-00209-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Accepted: 03/24/2020] [Indexed: 12/03/2022] Open
Abstract
Background Non-LTR retrotransposons often exhibit base composition that is markedly different from the nucleotide content of their host’s gene. For instance, the mammalian L1 element is AT-rich with a strong A bias on the positive strand, which results in a reduced transcription. It is plausible that the A-richness of mammalian L1 is a self-regulatory mechanism reflecting a trade-off between transposition efficiency and the deleterious effect of L1 on its host. We examined if the A-richness of L1 is a general feature of non-LTR retrotransposons or if different clades of elements have evolved different nucleotide content. We also investigated if elements belonging to the same clade evolved towards different base composition in different genomes or if elements from different clades evolved towards similar base composition in the same genome. Results We found that non-LTR retrotransposons differ in base composition among clades within the same host but also that elements belonging to the same clade differ in base composition among hosts. We showed that nucleotide content remains constant within the same host over extended period of evolutionary time, despite mutational patterns that should drive nucleotide content away from the observed base composition. Conclusions Our results suggest that base composition is evolving under selection and may be reflective of the long-term co-evolution between non-LTR retrotransposons and their host. Finally, the coexistence of elements with drastically different base composition suggests that these elements may be using different strategies to persist and multiply in the genome of their host.
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Affiliation(s)
- Robert P Ruggiero
- New York University Abu Dhabi, Saadiyat Island, Abu Dhabi, United Arab Emirates PO 129188
| | - Stéphane Boissinot
- New York University Abu Dhabi, Saadiyat Island, Abu Dhabi, United Arab Emirates PO 129188
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17
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Helleboid P, Heusel M, Duc J, Piot C, Thorball CW, Coluccio A, Pontis J, Imbeault M, Turelli P, Aebersold R, Trono D. The interactome of KRAB zinc finger proteins reveals the evolutionary history of their functional diversification. EMBO J 2019; 38:e101220. [PMID: 31403225 PMCID: PMC6745500 DOI: 10.15252/embj.2018101220] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2018] [Revised: 07/03/2019] [Accepted: 07/10/2019] [Indexed: 01/24/2023] Open
Abstract
Krüppel-associated box (KRAB)-containing zinc finger proteins (KZFPs) are encoded in the hundreds by the genomes of higher vertebrates, and many act with the heterochromatin-inducing KAP1 as repressors of transposable elements (TEs) during early embryogenesis. Yet, their widespread expression in adult tissues and enrichment at other genetic loci indicate additional roles. Here, we characterized the protein interactome of 101 of the ~350 human KZFPs. Consistent with their targeting of TEs, most KZFPs conserved up to placental mammals essentially recruit KAP1 and associated effectors. In contrast, a subset of more ancient KZFPs rather interacts with factors related to functions such as genome architecture or RNA processing. Nevertheless, KZFPs from coelacanth, our most distant KZFP-encoding relative, bind the cognate KAP1. These results support a hypothetical model whereby KZFPs first emerged as TE-controlling repressors, were continuously renewed by turnover of their hosts' TE loads, and occasionally produced derivatives that escaped this evolutionary flushing by development and exaptation of novel functions.
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Affiliation(s)
| | - Moritz Heusel
- Department of BiologyInstitute of Molecular Systems BiologyETH ZurichZurichSwitzerland
| | - Julien Duc
- School of Life SciencesEcole Polytechnique Fédérale de LausanneLausanneSwitzerland
| | - Cécile Piot
- School of Life SciencesEcole Polytechnique Fédérale de LausanneLausanneSwitzerland
| | - Christian W Thorball
- School of Life SciencesEcole Polytechnique Fédérale de LausanneLausanneSwitzerland
| | - Andrea Coluccio
- School of Life SciencesEcole Polytechnique Fédérale de LausanneLausanneSwitzerland
| | - Julien Pontis
- School of Life SciencesEcole Polytechnique Fédérale de LausanneLausanneSwitzerland
| | - Michaël Imbeault
- School of Life SciencesEcole Polytechnique Fédérale de LausanneLausanneSwitzerland
| | - Priscilla Turelli
- School of Life SciencesEcole Polytechnique Fédérale de LausanneLausanneSwitzerland
| | - Ruedi Aebersold
- Department of BiologyInstitute of Molecular Systems BiologyETH ZurichZurichSwitzerland
- Faculty of ScienceUniversity of ZurichZurichSwitzerland
| | - Didier Trono
- School of Life SciencesEcole Polytechnique Fédérale de LausanneLausanneSwitzerland
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18
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Saleh A, Macia A, Muotri AR. Transposable Elements, Inflammation, and Neurological Disease. Front Neurol 2019; 10:894. [PMID: 31481926 PMCID: PMC6710400 DOI: 10.3389/fneur.2019.00894] [Citation(s) in RCA: 87] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2019] [Accepted: 08/02/2019] [Indexed: 12/13/2022] Open
Abstract
Transposable Elements (TE) are mobile DNA elements that can replicate and insert themselves into different locations within the host genome. Their propensity to self-propagate has a myriad of consequences and yet their biological significance is not well-understood. Indeed, retrotransposons have evaded evolutionary attempts at repression and may contribute to somatic mosaicism. Retrotransposons are emerging as potent regulatory elements within the human genome. In the diseased state, there is mounting evidence that endogenous retroelements play a role in etiopathogenesis of inflammatory diseases, with a disposition for both autoimmune and neurological disorders. We postulate that active mobile genetic elements contribute more to human disease pathogenesis than previously thought.
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Affiliation(s)
- Aurian Saleh
- Department of Pediatrics, Rady Children's Hospital San Diego, University of California, San Diego, San Diego, CA, United States
| | - Angela Macia
- Department of Pediatrics, Rady Children's Hospital San Diego, University of California, San Diego, San Diego, CA, United States
| | - Alysson R Muotri
- Department of Pediatrics, Rady Children's Hospital San Diego, University of California, San Diego, San Diego, CA, United States
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19
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Blumenstiel JP. Birth, School, Work, Death, and Resurrection: The Life Stages and Dynamics of Transposable Element Proliferation. Genes (Basel) 2019; 10:genes10050336. [PMID: 31058854 PMCID: PMC6562965 DOI: 10.3390/genes10050336] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Revised: 04/18/2019] [Accepted: 04/23/2019] [Indexed: 12/18/2022] Open
Abstract
Transposable elements (TEs) can be maintained in sexually reproducing species even if they are harmful. However, the evolutionary strategies that TEs employ during proliferation can modulate their impact. In this review, I outline the different life stages of a TE lineage, from birth to proliferation to extinction. Through their interactions with the host, TEs can exploit diverse strategies that range from long-term coexistence to recurrent movement across species boundaries by horizontal transfer. TEs can also engage in a poorly understood phenomenon of TE resurrection, where TE lineages can apparently go extinct, only to proliferate again. By determining how this is possible, we may obtain new insights into the evolutionary dynamics of TEs and how they shape the genomes of their hosts.
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Affiliation(s)
- Justin P Blumenstiel
- Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, KS 66049, USA.
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20
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Wagstaff BJ, Wang L, Lai S, Derbes RS, Roy-Engel AM. Reviving a 60 million year old LINE-1 element. GENE REPORTS 2018; 11:74-78. [PMID: 30221208 DOI: 10.1016/j.genrep.2018.02.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Mobile elements have significantly impacted genome structure of most organisms. The continued activity of the mobile element, LINE-1 (L1), through time has contributed to the accumulation of over half a million L1 copies in the human genome. Most copies in the human genome belong to evolutionary older extinct L1s. Here we apply our previous published approach to "revive" the extinct L1 PA13A; an L1 family that was active about 60 million year ago (mya). The reconstructed L1PA13A is retrocompentent in culture, but shows a significantly lower level of activity in HeLa cells when compared to the modern L1 element (L1PA1) and a 40 million year old L1PA8. L1 elements code for two proteins (ORF1p and ORF2p) that are necessary for retrotransposition. Using PA13A-PA1 and PA13A-PA8 L1 chimeric elements, we determined that both the ORF1p and ORF2p contribute to the observed decrease in retrotransposition efficiency of L1PA13A. The lower retrotransposition rate of L1PA13A is consistent in both human and rodent cell lines. However, in rodent cells, the chimeric element L1PA:1-13 containing the modern L1PA1 ORF1p shows a recovery in the retrotransposition rate, suggestive that the L1PA13A ORF2p efficiently drives retrotransposition in these cells. The functionality of the L1PA13A ORF2p was further confirmed by demonstrating its ability to drive Alu retrotransposition in rodent cells. The variation in L1PA13A retrotransposition rates observed between rodent and human cells are suggestive that cellular environment significantly affects retrotransposition efficiency, which may be mediated through an interaction with ORF1p. Based on these observations, we speculate that the observed differences between cell lines may reflect an evolutionary adaptation of the L1 element to its host cell.
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Affiliation(s)
- Bradley J Wagstaff
- Tulane Cancer Center SL-66, Dept. of Epidemiology, Tulane University Health Sciences Center, 1430 Tulane Ave., New Orleans, LA 70112
| | - Linda Wang
- Tulane Cancer Center SL-66, Dept. of Epidemiology, Tulane University Health Sciences Center, 1430 Tulane Ave., New Orleans, LA 70112
| | - Susan Lai
- Tulane Cancer Center SL-66, Dept. of Epidemiology, Tulane University Health Sciences Center, 1430 Tulane Ave., New Orleans, LA 70112
| | - Rebecca S Derbes
- Tulane Cancer Center SL-66, Dept. of Epidemiology, Tulane University Health Sciences Center, 1430 Tulane Ave., New Orleans, LA 70112
| | - Astrid M Roy-Engel
- Tulane Cancer Center SL-66, Dept. of Epidemiology, Tulane University Health Sciences Center, 1430 Tulane Ave., New Orleans, LA 70112
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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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22
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Transcription factor profiling reveals molecular choreography and key regulators of human retrotransposon expression. Proc Natl Acad Sci U S A 2018; 115:E5526-E5535. [PMID: 29802231 PMCID: PMC6004460 DOI: 10.1073/pnas.1722565115] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Transposable elements (TEs) represent a substantial fraction of many eukaryotic genomes, and transcriptional regulation of these factors is important to determine TE activities in human cells. However, due to the repetitive nature of TEs, identifying transcription factor (TF)-binding sites from ChIP-sequencing (ChIP-seq) datasets is challenging. Current algorithms are focused on subtle differences between TE copies and thus bias the analysis to relatively old and inactive TEs. Here we describe an approach termed "MapRRCon" (mapping repeat reads to a consensus) which allows us to identify proteins binding to TE DNA sequences by mapping ChIP-seq reads to the TE consensus sequence after whole-genome alignment. Although this method does not assign binding sites to individual insertions in the genome, it provides a landscape of interacting TFs by capturing factors that bind to TEs under various conditions. We applied this method to screen TFs' interaction with L1 in human cells/tissues using ENCODE ChIP-seq datasets and identified 178 of the 512 TFs tested as bound to L1 in at least one biological condition with most of them (138) localized to the promoter. Among these L1-binding factors, we focused on Myc and CTCF, as they play important roles in cancer progression and 3D chromatin structure formation. Furthermore, we explored the transcriptomes of The Cancer Genome Atlas breast and ovarian tumor samples in which a consistent anti-/correlation between L1 and Myc/CTCF expression was observed, suggesting that these two factors may play roles in regulating L1 transcription during the development of such tumors.
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23
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Naufer MN, Furano AV, Williams MC. Protein-nucleic acid interactions of LINE-1 ORF1p. Semin Cell Dev Biol 2018; 86:140-149. [PMID: 29596909 PMCID: PMC6428221 DOI: 10.1016/j.semcdb.2018.03.019] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Revised: 03/19/2018] [Accepted: 03/23/2018] [Indexed: 11/03/2022]
Abstract
Long interspersed nuclear element 1 (LINE-1 or L1) is the dominant retrotransposon in mammalian genomes. L1 encodes two proteins ORF1p and ORF2p that are required for retrotransposition. ORF2p functions as the replicase. ORF1p is a coiled coil-mediated trimeric, high affinity RNA binding protein that packages its full- length coding transcript into an ORF2p-containing ribonucleoprotein (RNP) complex, the retrotransposition intermediate. ORF1p also is a nucleic acid chaperone that presumably facilitates the proposed nucleic acid remodeling steps involved in retrotransposition. Although detailed mechanistic understanding of ORF1p function in this process is lacking, recent studies showed that the rate at which ORF1p can form stable nucleic acid-bound oligomers in vitro is positively correlated with formation of an active L1 RNP as assayed in vivo using a cell culture-based retrotransposition assay. This rate was sensitive to minor amino acid changes in the coiled coil domain, which had no effect on nucleic acid chaperone activity. Additional studies linking the complex nucleic acid binding properties to the conformational changes of the protein are needed to understand how ORF1p facilitates retrotransposition.
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Affiliation(s)
- M Nabuan Naufer
- Northeastern University, Department of Physics, Boston, MA 02115, USA
| | - Anthony V Furano
- The Laboratory of Molecular and Cellular Biology, NIDDK, NIH, Bethesda, MD 20892, USA
| | - Mark C Williams
- Northeastern University, Department of Physics, Boston, MA 02115, USA.
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24
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Sookdeo A, Hepp CM, Boissinot S. Contrasted patterns of evolution of the LINE-1 retrotransposon in perissodactyls: the history of a LINE-1 extinction. Mob DNA 2018; 9:12. [PMID: 29610583 PMCID: PMC5872511 DOI: 10.1186/s13100-018-0117-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Accepted: 03/22/2018] [Indexed: 12/30/2022] Open
Abstract
Background LINE-1 (L1) is the dominant autonomously replicating non-LTR retrotransposon in mammals. Although our knowledge of L1 evolution across the tree of life has considerably improved in recent years, what we know of L1 evolution in mammals is biased and comes mostly from studies in primates (mostly human) and rodents (mostly mouse). It is unclear if patterns of evolution that are shared between those two groups apply to other mammalian orders. Here we performed a detailed study on the evolution of L1 in perissodactyls by making use of the complete genome of the domestic horse and of the white rhinoceros. This mammalian order offers an excellent model to study the extinction of L1 since the rhinoceros is one of the few mammalian species to have lost active L1. Results We found that multiple L1 lineages, carrying different 5’UTRs, have been simultaneously active during the evolution of perissodactyls. We also found that L1 has continuously amplified and diversified in horse. In rhinoceros, L1 was very prolific early on. Two successful families were simultaneously active until ~20my ago but became extinct suddenly at exactly the same time. Conclusions The general pattern of L1 evolution in perissodactyls is very similar to what was previously described in mouse and human, suggesting some commonalities in the way mammalian genomes interact with L1. We confirmed the extinction of L1 in rhinoceros and we discuss several possible mechanisms. Electronic supplementary material The online version of this article (10.1186/s13100-018-0117-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Akash Sookdeo
- 1Department of Biology, New York University, New York, NY USA
| | - Crystal M Hepp
- 2School of Informatics, Computing, and Cyber Systems, Northern Arizona University, Flagstaff, AZ USA
| | - Stéphane Boissinot
- 3New York University Abu Dhabi, Saadiyat Island, Abu Dhabi, United Arab Emirates
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25
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Khazina E, Weichenrieder O. Human LINE-1 retrotransposition requires a metastable coiled coil and a positively charged N-terminus in L1ORF1p. eLife 2018; 7:34960. [PMID: 29565245 PMCID: PMC5940361 DOI: 10.7554/elife.34960] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Accepted: 03/21/2018] [Indexed: 12/22/2022] Open
Abstract
LINE-1 (L1) is an autonomous retrotransposon, which acted throughout mammalian evolution and keeps contributing to human genotypic diversity, genetic disease and cancer. L1 encodes two essential proteins: L1ORF1p, a unique RNA-binding protein, and L1ORF2p, an endonuclease and reverse transcriptase. L1ORF1p contains an essential, but rapidly evolving N-terminal portion, homo-trimerizes via a coiled coil and packages L1RNA into large assemblies. Here, we determined crystal structures of the entire coiled coil domain of human L1ORF1p. We show that retrotransposition requires a non-ideal and metastable coiled coil structure, and a strongly basic L1ORF1p amino terminus. Human L1ORF1p therefore emerges as a highly calibrated molecular machine, sensitive to mutation but functional in different hosts. Our analysis rationalizes the locally rapid L1ORF1p sequence evolution and reveals striking mechanistic parallels to coiled coil-containing membrane fusion proteins. It also suggests how trimeric L1ORF1p could form larger meshworks and indicates critical novel steps in L1 retrotransposition. Almost half of the human genome consists of DNA strings that have been copied and pasted from one part of the genome to another many thousands of times. These strings of DNA are called mobile genetic elements. Mobile elements can disrupt important genes, causing disease and cancer, but they can also drive evolution. Presently, only one type of mobile element, called LINE-1, is active in the human genome and able to multiply without help from other mobile elements. LINE-1 DNA is ‘transcribed’ to form molecules of LINE-1 RNA, which can then be ‘translated’ into two distinct proteins. These bind to LINE-1 RNA, which then gets back-transcribed into DNA and inserted as a new LINE-1 element in a new region of the genome. One of the two proteins, called L1ORF1p, forms complexes where three copies of the protein come together. These ‘trimers’ cover and protect LINE-1 RNA and are required for LINE-1 mobility. Different versions of L1ORF1p are found in different animals. Part of the protein is the same across all mammals, and this ‘conserved’ part controls the ability of L1ORF1p to bind to RNA. The non-conserved part of L1ORF1p differs even between humans and their closest animal relatives and little was known about its structure or role. However, this rapidly evolving part of L1ORF1p is essential for LINE-1 mobility. Using X-ray crystallography, Khazina and Weichenrieder obtained a molecular snapshot of the part of L1ORF1p that interacts with other copies of the protein to form trimers. Combined with earlier snapshots of L1ORF1p’s conserved part, this generated a complete structural model of the L1ORF1p trimer. Additional biophysical characterizations suggest that L1ORF1p trimers form a semi-stable structure that can partially open up, indicating how trimers could form larger assemblies of L1ORF1p on LINE-1 RNA. Indeed, the need to maintain a semi-stable structure could explain why L1ORF1p is evolving so rapidly. A second important finding is that the beginning of L1ORF1p needs to be positively charged – a requirement that warrants further exploration. The structural and mechanistic insight into L1ORF1p points to critical new steps in LINE-1 mobilization. It will help to design inhibitor molecules with the goal to halt the mobilization process at various points and to dissect such steps in great detail. Understanding how to control LINE-1 mobility could help to improve stem cell therapies and reproduction assistance techniques, due to the fact that LINE-1 mobility is a potential source of mutation in stem cells, egg and sperm cells, and newly formed embryos.
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Affiliation(s)
- Elena Khazina
- Department of Biochemistry, Max Planck Institute for Developmental Biology, Tübingen, Germany
| | - Oliver Weichenrieder
- Department of Biochemistry, Max Planck Institute for Developmental Biology, Tübingen, Germany
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26
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Boissinot S, Sookdeo A. The Evolution of LINE-1 in Vertebrates. Genome Biol Evol 2018; 8:3485-3507. [PMID: 28175298 PMCID: PMC5381506 DOI: 10.1093/gbe/evw247] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/03/2016] [Indexed: 12/21/2022] Open
Abstract
The abundance and diversity of the LINE-1 (L1) retrotransposon differ greatly among vertebrates. Mammalian genomes contain hundreds of thousands L1s that have accumulated since the origin of mammals. A single group of very similar elements is active at a time in mammals, thus a single lineage of active families has evolved in this group. In contrast, non-mammalian genomes (fish, amphibians, reptiles) harbor a large diversity of concurrently transposing families, which are all represented by very small number of recently inserted copies. Why the pattern of diversity and abundance of L1 is so different among vertebrates remains unknown. To address this issue, we performed a detailed analysis of the evolution of active L1 in 14 mammals and in 3 non-mammalian vertebrate model species. We examined the evolution of base composition and codon bias, the general structure, and the evolution of the different domains of L1 (5′UTR, ORF1, ORF2, 3′UTR). L1s differ substantially in length, base composition, and structure among vertebrates. The most variation is found in the 5′UTR, which is longer in amniotes, and in the ORF1, which tend to evolve faster in mammals. The highly divergent L1 families of lizard, frog, and fish share species-specific features suggesting that they are subjected to the same functional constraints imposed by their host. The relative conservation of the 5′UTR and ORF1 in non-mammalian vertebrates suggests that the repression of transposition by the host does not act in a sequence-specific manner and did not result in an arms race, as is observed in mammals.
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27
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de Sotero-Caio CG, Cabral-de-Mello DC, Calixto MDS, Valente GT, Martins C, Loreto V, de Souza MJ, Santos N. Centromeric enrichment of LINE-1 retrotransposons and its significance for the chromosome evolution of Phyllostomid bats. Chromosome Res 2017; 25:313-325. [PMID: 28916913 DOI: 10.1007/s10577-017-9565-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2017] [Revised: 08/24/2017] [Accepted: 08/28/2017] [Indexed: 10/18/2022]
Abstract
Despite their ubiquitous incidence, little is known about the chromosomal distribution of long interspersed elements (LINEs) in mammalian genomes. Phyllostomid bats, characterized by lineages with distinct trends of chromosomal evolution coupled with remarkable ecological and taxonomic diversity, represent good models to understand how these repetitive sequences contribute to the evolution of genome architecture and its link to lineage diversification. To test the hypothesis that LINE-1 sequences were important modifiers of bat genome architecture, we characterized the distribution of LINE-1-derived sequences on genomes of 13 phyllostomid species within a phylogenetic framework. We found massive accumulation of LINE-1 elements in the centromeres of most species: a rare phenomenon on mammalian genomes. We hypothesize that expansion of these elements has occurred early in the radiation of phyllostomids and recurred episodically. LINE-1 expansions on centromeric heterochromatin probably spurred chromosomal change before the radiation of phyllostomids into the extant 11 subfamilies and contributed to the high degree of karyotypic variation observed among different lineages. Understanding centromere architecture in a variety of taxa promises to explain how lineage-specific changes on centromere structure can contribute to karyotypic diversity while not disrupting functional constraints for proper cell division.
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Affiliation(s)
- Cibele Gomes de Sotero-Caio
- Departamento de Genética, Laboratório de Genética e Citogenética Animal e Humana, UFPE-Universidade Federal de Pernambuco, Av. da Engenharia s/n; Cidade Universitária, Recife, PE, CEP:50740-600, Brazil. .,Department of Biological Sciences, Texas Tech University, Lubbock, TX, USA.
| | - Diogo Cavalcanti Cabral-de-Mello
- Departamento de Biologia, Grupo de Estudos em Citogenômica e Evolução Animal, UNESP-Universidade Estadual Paulista, Instituto de Biociências, Rio Claro, SP, Brazil
| | - Merilane da Silva Calixto
- Departamento de Genética, Laboratório de Genética e Citogenética Animal e Humana, UFPE-Universidade Federal de Pernambuco, Av. da Engenharia s/n; Cidade Universitária, Recife, PE, CEP:50740-600, Brazil.,Centro de Saúde e Tecnologia, Unidade Acadêmica de Ciências Biológicas, UFCG-Universidade Federal de Campina Grande, Patos, PB, Brazil
| | - Guilherme Targino Valente
- Departamento de Bioprocessos e Biotecnologia da Faculdade de Ciências Agronômicas, UNESP-Universidade Estadual Paulista, Botucatu, SP, Brazil
| | - Cesar Martins
- Departamento de Morfologia, Laboratório Genômica Integrativa, UNESP-Universidade Estadual Paulista, Botucatu, SP, Brazil
| | - Vilma Loreto
- Departamento de Genética, Laboratório de Genética e Citogenética Animal e Humana, UFPE-Universidade Federal de Pernambuco, Av. da Engenharia s/n; Cidade Universitária, Recife, PE, CEP:50740-600, Brazil
| | - Maria José de Souza
- Departamento de Genética, Laboratório de Genética e Citogenética Animal e Humana, UFPE-Universidade Federal de Pernambuco, Av. da Engenharia s/n; Cidade Universitária, Recife, PE, CEP:50740-600, Brazil
| | - Neide Santos
- Departamento de Genética, Laboratório de Genética e Citogenética Animal e Humana, UFPE-Universidade Federal de Pernambuco, Av. da Engenharia s/n; Cidade Universitária, Recife, PE, CEP:50740-600, Brazil
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28
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MacLennan M, García-Cañadas M, Reichmann J, Khazina E, Wagner G, Playfoot CJ, Salvador-Palomeque C, Mann AR, Peressini P, Sanchez L, Dobie K, Read D, Hung CC, Eskeland R, Meehan RR, Weichenrieder O, García-Pérez JL, Adams IR. Mobilization of LINE-1 retrotransposons is restricted by Tex19.1 in mouse embryonic stem cells. eLife 2017; 6:e26152. [PMID: 28806172 PMCID: PMC5570191 DOI: 10.7554/elife.26152] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2017] [Accepted: 07/11/2017] [Indexed: 12/21/2022] Open
Abstract
Mobilization of retrotransposons to new genomic locations is a significant driver of mammalian genome evolution, but these mutagenic events can also cause genetic disorders. In humans, retrotransposon mobilization is mediated primarily by proteins encoded by LINE-1 (L1) retrotransposons, which mobilize in pluripotent cells early in development. Here we show that TEX19.1, which is induced by developmentally programmed DNA hypomethylation, can directly interact with the L1-encoded protein L1-ORF1p, stimulate its polyubiquitylation and degradation, and restrict L1 mobilization. We also show that TEX19.1 likely acts, at least in part, through promoting the activity of the E3 ubiquitin ligase UBR2 towards L1-ORF1p. Moreover, loss of Tex19.1 increases L1-ORF1p levels and L1 mobilization in pluripotent mouse embryonic stem cells, implying that Tex19.1 prevents de novo retrotransposition in the pluripotent phase of the germline cycle. These data show that post-translational regulation of L1 retrotransposons plays a key role in maintaining trans-generational genome stability in mammals.
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Affiliation(s)
- Marie MacLennan
- MRC Human Genetics Unit,
MRC Institute of Genetics and Molecular Medicine,
University of Edinburgh, Edinburgh, United
Kingdom
| | - Marta García-Cañadas
- Centro de Genómica e
Investigación Oncológica (GENYO), Pfizer-Universidad de
Granada-Junta de Andalucía, PTS Granada, Granada,
Spain
| | - Judith Reichmann
- MRC Human Genetics Unit,
MRC Institute of Genetics and Molecular Medicine,
University of Edinburgh, Edinburgh, United
Kingdom
| | - Elena Khazina
- Department of
Biochemistry, Max Planck Institute for Developmental
Biology, Tübingen, Germany
| | - Gabriele Wagner
- Department of
Biochemistry, Max Planck Institute for Developmental
Biology, Tübingen, Germany
| | - Christopher J Playfoot
- MRC Human Genetics Unit,
MRC Institute of Genetics and Molecular Medicine,
University of Edinburgh, Edinburgh, United
Kingdom
| | - Carmen Salvador-Palomeque
- Centro de Genómica e
Investigación Oncológica (GENYO), Pfizer-Universidad de
Granada-Junta de Andalucía, PTS Granada, Granada,
Spain
| | - Abigail R Mann
- MRC Human Genetics Unit,
MRC Institute of Genetics and Molecular Medicine,
University of Edinburgh, Edinburgh, United
Kingdom
| | - Paula Peressini
- Centro de Genómica e
Investigación Oncológica (GENYO), Pfizer-Universidad de
Granada-Junta de Andalucía, PTS Granada, Granada,
Spain
| | - Laura Sanchez
- Centro de Genómica e
Investigación Oncológica (GENYO), Pfizer-Universidad de
Granada-Junta de Andalucía, PTS Granada, Granada,
Spain
| | - Karen Dobie
- MRC Human Genetics Unit,
MRC Institute of Genetics and Molecular Medicine,
University of Edinburgh, Edinburgh, United
Kingdom
| | - David Read
- MRC Human Genetics Unit,
MRC Institute of Genetics and Molecular Medicine,
University of Edinburgh, Edinburgh, United
Kingdom
| | - Chao-Chun Hung
- MRC Human Genetics Unit,
MRC Institute of Genetics and Molecular Medicine,
University of Edinburgh, Edinburgh, United
Kingdom
| | - Ragnhild Eskeland
- Department of
Biosciences, University of Oslo,
Oslo,
Norway
- Norwegian Center for
Stem Cell Research, Department of Immunology, Oslo
University Hospital, Oslo, Norway
| | - Richard R Meehan
- MRC Human Genetics Unit,
MRC Institute of Genetics and Molecular Medicine,
University of Edinburgh, Edinburgh, United
Kingdom
| | - Oliver Weichenrieder
- Department of
Biochemistry, Max Planck Institute for Developmental
Biology, Tübingen, Germany
| | - Jose Luis García-Pérez
- MRC Human Genetics Unit,
MRC Institute of Genetics and Molecular Medicine,
University of Edinburgh, Edinburgh, United
Kingdom
- Centro de Genómica e
Investigación Oncológica (GENYO), Pfizer-Universidad de
Granada-Junta de Andalucía, PTS Granada, Granada,
Spain
| | - Ian R Adams
- MRC Human Genetics Unit,
MRC Institute of Genetics and Molecular Medicine,
University of Edinburgh, Edinburgh, United
Kingdom
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29
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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: 159] [Impact Index Per Article: 22.7] [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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30
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Penzkofer T, Jäger M, Figlerowicz M, Badge R, Mundlos S, Robinson PN, Zemojtel T. L1Base 2: more retrotransposition-active LINE-1s, more mammalian genomes. Nucleic Acids Res 2016; 45:D68-D73. [PMID: 27924012 PMCID: PMC5210629 DOI: 10.1093/nar/gkw925] [Citation(s) in RCA: 87] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2016] [Revised: 09/28/2016] [Accepted: 10/05/2016] [Indexed: 12/28/2022] Open
Abstract
LINE-1 (L1) insertions comprise as much as 17% of the human genome sequence, and similar proportions have been recorded for other mammalian species. Given the established role of L1 retrotransposons in shaping mammalian genomes, it becomes an important task to track and annotate the sources of this activity: full length elements, able to encode the cis and trans acting components of the retrotransposition machinery. The L1Base database (http://l1base.charite.de) contains annotated full-length sequences of LINE-1 transposons including putatively active L1s. For the new version of L1Base, a LINE-1 annotation tool, L1Xplorer, has been used to mine potentially active L1 retrotransposons from the reference genome sequences of 17 mammals. The current release of the human genome, GRCh38, contains 146 putatively active L1 elements or full length intact L1 elements (FLIs). The newest versions of the mouse, GRCm38 and the rat, Rnor_6.0, genomes contain 2811 and 492 FLIs, respectively. Most likely reflecting the current level of completeness of the genome project, the latest reference sequence of the common chimpanzee genome, PT 2.19, only contains 19 FLIs. Of note, the current assemblies of the dog, CF 3.1 and the sheep, OA 3.1, genomes contain 264 and 598 FLIs, respectively. Further developments in the new version of L1Base include an updated website with implementation of modern web server technologies. including a more responsive design for an improved user experience, as well as the addition of data sharing capabilities for L1Xplorer annotation.
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Affiliation(s)
- Tobias Penzkofer
- Department of Radiology, Charité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany
| | - Marten Jäger
- Institut für Medizinische Genetik und Humangenetik, Charité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany
| | - Marek Figlerowicz
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, 60-569 Poznan, Poland
| | - Richard Badge
- Department of Genetics, University of Leicester, Leicester, LE1 7RH, UK
| | - Stefan Mundlos
- Institut für Medizinische Genetik und Humangenetik, Charité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany
| | - Peter N Robinson
- Institut für Medizinische Genetik und Humangenetik, Charité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany.,The Jackson Laboratory for Genomic medicine, 10 Discovery Drive, Farmington, CT 06032, USA
| | - Tomasz Zemojtel
- Institut für Medizinische Genetik und Humangenetik, Charité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany .,Institute of Bioorganic Chemistry, Polish Academy of Sciences, 60-569 Poznan, Poland
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31
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Abstract
Retrotransposons have generated about 40 % of the human genome. This review examines the strategies the cell has evolved to coexist with these genomic "parasites", focussing on the non-long terminal repeat retrotransposons of humans and mice. Some of the restriction factors for retrotransposition, including the APOBECs, MOV10, RNASEL, SAMHD1, TREX1, and ZAP, also limit replication of retroviruses, including HIV, and are part of the intrinsic immune system of the cell. Many of these proteins act in the cytoplasm to degrade retroelement RNA or inhibit its translation. Some factors act in the nucleus and involve DNA repair enzymes or epigenetic processes of DNA methylation and histone modification. RISC and piRNA pathway proteins protect the germline. Retrotransposon control is relaxed in some cell types, such as neurons in the brain, stem cells, and in certain types of disease and cancer, with implications for human health and disease. This review also considers potential pitfalls in interpreting retrotransposon-related data, as well as issues to consider for future research.
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Affiliation(s)
- John L. Goodier
- McKusick-Nathans Institute for Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD USA 212051
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32
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Naufer MN, Callahan KE, Cook PR, Perez-Gonzalez CE, Williams MC, Furano AV. L1 retrotransposition requires rapid ORF1p oligomerization, a novel coiled coil-dependent property conserved despite extensive remodeling. Nucleic Acids Res 2015; 44:281-93. [PMID: 26673717 PMCID: PMC4705668 DOI: 10.1093/nar/gkv1342] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Accepted: 11/17/2015] [Indexed: 12/16/2022] Open
Abstract
Detailed mechanistic understanding of L1 retrotransposition is sparse, particularly with respect to ORF1p, a coiled coil-mediated homotrimeric nucleic acid chaperone that can form tightly packed oligomers on nucleic acids. Although the coiled coil motif is highly conserved, it is uniquely susceptible to evolutionary change. Here we studied three ORF1 proteins: a modern human one (111p), its resuscitated primate ancestor (555p) and a mosaic modern protein (151p) wherein 9 of the 30 coiled coil substitutions retain their ancestral state. While 111p and 555p equally supported retrotransposition, 151p was inactive. Nonetheless, they were fully active in bulk assays of nucleic acid interactions including chaperone activity. However, single molecule assays showed that 151p trimers form stably bound oligomers on ssDNA at <1/10th the rate of the active proteins, revealing that oligomerization rate is a novel critical parameter of ORF1p activity in retrotransposition conserved for at least the last 25 Myr of primate evolution.
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Affiliation(s)
- M Nabuan Naufer
- Northeastern University, Department of Physics, Boston, MA 02115, USA
| | - Kathryn E Callahan
- Laboratory of Cellular and Molecular Biology, NIDDK, National Institutes of Health, Bethesda, MD 20892, USA
| | - Pamela R Cook
- Laboratory of Cellular and Molecular Biology, NIDDK, National Institutes of Health, Bethesda, MD 20892, USA
| | - Cesar E Perez-Gonzalez
- Laboratory of Cellular and Molecular Biology, NIDDK, National Institutes of Health, Bethesda, MD 20892, USA
| | - Mark C Williams
- Northeastern University, Department of Physics, Boston, MA 02115, USA
| | - Anthony V Furano
- Laboratory of Cellular and Molecular Biology, NIDDK, National Institutes of Health, Bethesda, MD 20892, USA
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33
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Abstract
Although members of the L1 (LINE-1) clade of non-LTR retrotransposons can be deleterious, the L1 clade has remained active in most mammals for ∼100 million years and generated almost 40% of the human genome. The details of L1-host interaction are largely unknown, however. Here we report that L1 activity requires phosphorylation of the protein encoded by the L1 ORF1 (ORF1p). Critical phospho-acceptor residues (two serines and two threonines) reside in four conserved proline-directed protein kinase (PDPK) target sites. The PDPK family includes mitogen-activated protein kinases and cyclin-dependent kinases. Mutation of any PDPK phospho-acceptor inhibits L1 retrotransposition. The phosphomimetic aspartic acid can restore activity at the two serine sites, but not at either threonine site, where it is strongly inhibitory. ORF1p also contains conserved PDPK docking sites, which promote specific interaction of PDPKs with their targets. As expected, mutations in these sites also inhibit L1 activity. PDPK mutations in ORF1p that inactivate L1 have no significant effect on the ability of ORF1p to anneal RNA in vitro, an important biochemical property of the protein. We show that phosphorylated PDPK sites in ORF1p are required for an interaction with the peptidyl prolyl isomerase 1 (Pin1), a critical component of PDPK-mediated regulation. Pin1 acts via isomerization of proline side chains at phosphorylated PDPK motifs, thereby affecting substrate conformation and activity. Our demonstration that L1 activity is dependent on and integrated with cellular phosphorylation regulatory cascades significantly increases our understanding of interactions between L1 and its host.
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34
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Streva VA, Jordan VE, Linker S, Hedges DJ, Batzer MA, Deininger PL. Sequencing, identification and mapping of primed L1 elements (SIMPLE) reveals significant variation in full length L1 elements between individuals. BMC Genomics 2015; 16:220. [PMID: 25887476 PMCID: PMC4381410 DOI: 10.1186/s12864-015-1374-y] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Accepted: 02/20/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND There are over a half a million copies of L1 retroelements in the human genome which are responsible for as much as 0.5% of new human genetic diseases. Most new L1 inserts arise from young source elements that are polymorphic in the human genome. Highly active polymorphic "hot" L1 source elements have been shown to be capable of extremely high levels of mobilization and result in numerous instances of disease. Additionally, hot polymorphic L1s have been described to be highly active within numerous cancer genomes. These hot L1s result in mutagenesis by insertion of new L1 copies elsewhere in the genome, but also have been shown to generate additional full length L1 insertions which are also hot and able to further retrotranspose. Through this mechanism, hot L1s may amplify within a tumor and result in a continued cycle of mutagenesis. RESULTS AND CONCLUSIONS We have developed a method to detect full-length, polymorphic L1 elements using a targeted next generation sequencing approach, Sequencing Identification and Mapping of Primed L1 Elements (SIMPLE). SIMPLE has 94% sensitivity and detects nearly all full-length L1 elements in a genome. SIMPLE will allow researchers to identify hot mutagenic full-length L1s as potential drivers of genome instability. Using SIMPLE we find that the typical individual has approximately 100 non-reference, polymorphic L1 elements in their genome. These elements are at relatively low population frequencies relative to previously identified polymorphic L1 elements and demonstrate the tremendous diversity in potentially active L1 elements in the human population.
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Affiliation(s)
- Vincent A Streva
- Tulane Cancer Center and Department of Epidemiology, Tulane University, New Orleans, LA, USA. .,Present Address: Division of Infectious Diseases, Boston Children's Hospital and Harvard Medical School, Boston, MA, USA.
| | - Vallmer E Jordan
- Department of Biology, Louisiana State University, Baton Rouge, LA, USA.
| | - Sara Linker
- Department of Human Genetics, University of Miami Miller School of Medicine, Miami, FL, USA.
| | - Dale J Hedges
- Department of Internal Medicine, The Ohio State University, Columbus, OH, USA.
| | - Mark A Batzer
- Department of Biology, Louisiana State University, Baton Rouge, LA, USA.
| | - Prescott L Deininger
- Tulane Cancer Center and Department of Epidemiology, Tulane University, New Orleans, LA, USA.
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35
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Abstract
Retroelements, constituting about 50% of the human genome, both contribute to its evolution and threaten its integrity and are thus silenced during development. Jacobs et al. (2014) identify sequence-specific KRAB-ZNF proteins that repress subsets of L1 and SVA retrotransposons in humans, highlighting the evolutionary interplay between retroelements and their hosts.
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Affiliation(s)
- Michael Imbeault
- School of Life Sciences, École Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Didier Trono
- School of Life Sciences, École Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland.
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36
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Positive selection and multiple losses of the LINE-1-derived L1TD1 gene in mammals suggest a dual role in genome defense and pluripotency. PLoS Genet 2014; 10:e1004531. [PMID: 25211013 PMCID: PMC4161310 DOI: 10.1371/journal.pgen.1004531] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2013] [Accepted: 06/10/2014] [Indexed: 11/19/2022] Open
Abstract
Mammalian genomes comprise many active and fossilized retroelements. The obligate requirement for retroelement integration affords host genomes an opportunity to 'domesticate' retroelement genes for their own purpose, leading to important innovations in genome defense and placentation. While many such exaptations involve retroviruses, the L1TD1 gene is the only known domesticated gene whose protein-coding sequence is almost entirely derived from a LINE-1 (L1) retroelement. Human L1TD1 has been shown to play an important role in pluripotency maintenance. To investigate how this role was acquired, we traced the origin and evolution of L1TD1. We find that L1TD1 originated in the common ancestor of eutherian mammals, but was lost or pseudogenized multiple times during mammalian evolution. We also find that L1TD1 has evolved under positive selection during primate and mouse evolution, and that one prosimian L1TD1 has 'replenished' itself with a more recent L1 ORF1 from the prosimian genome. These data suggest that L1TD1 has been recurrently selected for functional novelty, perhaps for a role in genome defense. L1TD1 loss is associated with L1 extinction in several megabat lineages, but not in sigmodontine rodents. We hypothesize that L1TD1 could have originally evolved for genome defense against L1 elements. Later, L1TD1 may have become incorporated into pluripotency maintenance in some lineages. Our study highlights the role of retroelement gene domestication in fundamental aspects of mammalian biology, and that such domesticated genes can adopt different functions in different lineages.
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LINE-1 retrotransposons: from 'parasite' sequences to functional elements. J Appl Genet 2014; 56:133-45. [PMID: 25106509 DOI: 10.1007/s13353-014-0241-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2014] [Revised: 07/24/2014] [Accepted: 07/25/2014] [Indexed: 10/24/2022]
Abstract
Long interspersed nuclear elements-1 (LINE-1) are the most abundant and active retrotransposons in the mammalian genomes. Traditionally, the occurrence of LINE-1 sequences in the genome of mammals has been explained by the selfish DNA hypothesis. Nevertheless, recently, it has also been argued that these sequences could play important roles in these genomes, as in the regulation of gene expression, genome modelling and X-chromosome inactivation. The non-random chromosomal distribution is a striking feature of these retroelements that somehow reflects its functionality. In the present study, we have isolated and analysed a fraction of the open reading frame 2 (ORF2) LINE-1 sequence from three rodent species, Cricetus cricetus, Peromyscus eremicus and Praomys tullbergi. Physical mapping of the isolated sequences revealed an interspersed longitudinal AT pattern of distribution along all the chromosomes of the complement in the three genomes. A detailed analysis shows that these sequences are preferentially located in the euchromatic regions, although some signals could be detected in the heterochromatin. In addition, a coincidence between the location of imprinted gene regions (as Xist and Tsix gene regions) and the LINE-1 retroelements was also observed. According to these results, we propose an involvement of LINE-1 sequences in different genomic events as gene imprinting, X-chromosome inactivation and evolution of repetitive sequences located at the heterochromatic regions (e.g. satellite DNA sequences) of the rodents' genomes analysed.
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Ivancevic AM, Walsh AM, Kortschak RD, Adelson DL. Jumping the fine LINE between species: horizontal transfer of transposable elements in animals catalyses genome evolution. Bioessays 2013; 35:1071-82. [PMID: 24003001 DOI: 10.1002/bies.201300072] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Horizontal transfer (HT) is the transmission of genetic material between non-mating species, a phenomenon thought to occur rarely in multicellular eukaryotes. However, many transposable elements (TEs) are not only capable of HT, but have frequently jumped between widely divergent species. Here we review and integrate reported cases of HT in retrotransposons of the BovB family, and DNA transposons, over a broad range of animals spanning all continents. Our conclusions challenge the paradigm that HT in vertebrates is restricted to infective long terminal repeat (LTR) retrotransposons or retroviruses. This raises the possibility that other non-LTR retrotransposons, such as L1 or CR1 elements, believed to be only vertically transmitted, can horizontally transfer between species. Growing evidence indicates that the process of HT is much more general across different TEs and species than previously believed, and that it likely shapes eukaryotic genomes and catalyses genome evolution.
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Affiliation(s)
- Atma M Ivancevic
- School of Molecular and Biomedical Science, University of Adelaide, Adelaide, SA, Australia
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Chen C, Bartenhagen C, Gombert M, Okpanyi V, Binder V, Röttgers S, Bradtke J, Teigler-Schlegel A, Harbott J, Ginzel S, Thiele R, Fischer U, Dugas M, Hu J, Borkhardt A. Next-generation-sequencing-based risk stratification and identification of new genes involved in structural and sequence variations in near haploid lymphoblastic leukemia. Genes Chromosomes Cancer 2013; 52:564-79. [DOI: 10.1002/gcc.22054] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2012] [Accepted: 01/29/2013] [Indexed: 01/10/2023] Open
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Sookdeo A, Hepp CM, McClure MA, Boissinot S. Revisiting the evolution of mouse LINE-1 in the genomic era. Mob DNA 2013; 4:3. [PMID: 23286374 PMCID: PMC3600994 DOI: 10.1186/1759-8753-4-3] [Citation(s) in RCA: 121] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2012] [Accepted: 10/25/2012] [Indexed: 11/10/2022] Open
Abstract
Background LINE-1 (L1) is the dominant category of transposable elements in placental mammals. L1 has significantly affected the size and structure of all mammalian genomes and understanding the nature of the interactions between L1 and its mammalian host remains a question of crucial importance in comparative genomics. For this reason, much attention has been dedicated to the evolution of L1. Among the most studied elements is the mouse L1 which has been the subject of a number of studies in the 1980s and 1990s. These seminal studies, performed in the pre-genomic era when only a limited number of L1 sequences were available, have significantly improved our understanding of L1 evolution. Yet, no comprehensive study on the evolution of L1 in mouse has been performed since the completion of this genome sequence. Results Using the Genome Parsing Suite we performed the first evolutionary analysis of mouse L1 over the entire length of the element. This analysis indicates that the mouse L1 has recruited novel 5’UTR sequences more frequently than previously thought and that the simultaneous activity of non-homologous promoters seems to be one of the conditions for the co-existence of multiple L1 families or lineages. In addition the exchange of genetic information between L1 families is not limited to the 5’UTR as evidence of inter-family recombination was observed in ORF1, ORF2, and the 3’UTR. In contrast to the human L1, there was little evidence of rapid amino-acid replacement in the coiled-coil of ORF1, although this region is structurally unstable. We propose that the structural instability of the coiled-coil domain might be adaptive and that structural changes in this region are selectively equivalent to the rapid evolution at the amino-acid level reported in the human lineage. Conclusions The pattern of evolution of L1 in mouse shows some similarity with human suggesting that the nature of the interactions between L1 and its host might be similar in these two species. Yet, some notable differences, particularly in the evolution of ORF1, suggest that the molecular mechanisms involved in host-L1 interactions might be different in these two species.
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Affiliation(s)
- Akash Sookdeo
- Department of Biology, Queens College, the City University of New York, 65-30 Kissena Boulevard, Flushing, NY 11367-1597, USA.
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Goodier JL, Cheung LE, Kazazian HH. MOV10 RNA helicase is a potent inhibitor of retrotransposition in cells. PLoS Genet 2012; 8:e1002941. [PMID: 23093941 PMCID: PMC3475670 DOI: 10.1371/journal.pgen.1002941] [Citation(s) in RCA: 166] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2012] [Accepted: 07/23/2012] [Indexed: 01/31/2023] Open
Abstract
MOV10 protein, a putative RNA helicase and component of the RNA–induced silencing complex (RISC), inhibits retrovirus replication. We show that MOV10 also severely restricts human LINE1 (L1), Alu, and SVA retrotransposons. MOV10 associates with the L1 ribonucleoprotein particle, along with other RNA helicases including DDX5, DHX9, DDX17, DDX21, and DDX39A. However, unlike MOV10, these other helicases do not strongly inhibit retrotransposition, an activity dependent upon intact helicase domains. MOV10 association with retrotransposons is further supported by its colocalization with L1 ORF1 protein in stress granules, by cytoplasmic structures associated with RNA silencing, and by the ability of MOV10 to reduce endogenous and ectopic L1 expression. The majority of the human genome is repetitive DNA, most of which is the detritus of millions of years of accumulated retrotransposition. Retrotransposons remain active mutagens, and their insertion can disrupt gene function. Therefore, the host has evolved defense mechanisms to protect against retrotransposition, an arsenal we are only beginning to understand. With homologs in other vertebrates, insects, and plants, MOV10 may represent an ancient and innate form of immunity against both infective viruses and endogenous retroelements. LINE1s, the only active autonomous mobile DNA in humans, occupy at least 17% of our genome. It is believed that about 100 L1s are potentially active in any individual diploid genome. The L1 has also been responsible for genomic insertion of processed pseudogenes and more than a million non-autonomous retrotransposons, mainly Alus and SVAs. Together, this mass of genomic baggage has had, and continues to have, profound effects on gene organization and expression. Consequently a number of molecular mechanisms have evolved to prevent the unchecked expansion of endogenous retroelements. We demonstrate that the putative RNA helicase MOV10, recently discovered to limit production and infectivity of retroviruses, also profoundly inhibits retrotransposition of L1s, Alus, and SVAs in cell culture. Microscopy and immunoprecipitation show a close association of MOV10 protein with the L1 ribonucleoprotein particle. This study reveals a novel factor that interacts with the L1 retrotransposon to modulate its activity, and it increases our understanding of the means by which the cell coexists with these genomic “parasites.”
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Affiliation(s)
- John L Goodier
- McKusick-Nathans Institute for Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
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Wagstaff BJ, Kroutter EN, Derbes RS, Belancio VP, Roy-Engel AM. Molecular reconstruction of extinct LINE-1 elements and their interaction with nonautonomous elements. Mol Biol Evol 2012; 30:88-99. [PMID: 22918960 PMCID: PMC3525338 DOI: 10.1093/molbev/mss202] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Non-long terminal repeat retroelements continue to impact the human genome through
cis-activity of long interspersed element-1 (LINE-1 or L1) and trans-mobilization of Alu.
Current activity is dominated by modern subfamilies of these elements, leaving behind an
evolutionary graveyard of extinct Alu and L1 subfamilies. Because Alu is a nonautonomous
element that relies on L1 to retrotranspose, there is the possibility that competition
between these elements has driven selection and antagonistic coevolution between Alu and
L1. Through analysis of synonymous versus nonsynonymous codon evolution across L1
subfamilies, we find that the C-terminal ORF2 cys domain experienced a dramatic increase
in amino acid substitution rate in the transition from L1PA5 to L1PA4 subfamilies. This
observation coincides with the previously reported rapid evolution of ORF1 during the same
transition period. Ancestral Alu sequences have been previously reconstructed, as their
short size and ubiquity have made it relatively easy to retrieve consensus sequences from
the human genome. In contrast, creating constructs of extinct L1 copies is a more
laborious task. Here, we report our efforts to recreate and evaluate the
retrotransposition capabilities of two ancestral L1 elements, L1PA4 and L1PA8 that were
active ∼18 and ∼40 Ma, respectively. Relative to the modern L1PA1 subfamily, we
find that both elements are similarly active in a cell culture retrotransposition assay in
HeLa, and both are able to efficiently trans-mobilize Alu elements from several
subfamilies. Although we observe some variation in Alu subfamily retrotransposition
efficiency, any coevolution that may have occurred between LINEs and SINEs is not evident
from these data. Population dynamics and stochastic variation in the number of active
source elements likely play an important role in individual LINE or SINE subfamily
amplification. If coevolution also contributes to changing retrotransposition rates and
the progression of subfamilies, cell factors are likely to play an important mediating
role in changing LINE-SINE interactions over evolutionary time.
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Affiliation(s)
- Bradley J Wagstaff
- Department of Epidemiology and Tulane Cancer Center, Tulane University, New Orleans, LA, USA
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Abstract
Mobile DNAs have had a central role in shaping our genome. More than half of our DNA is comprised of interspersed repeats resulting from replicative copy and paste events of retrotransposons. Although most are fixed, incapable of templating new copies, there are important exceptions to retrotransposon quiescence. De novo insertions cause genetic diseases and cancers, though reliably detecting these occurrences has been difficult. New technologies aimed at uncovering polymorphic insertions reveal that mobile DNAs provide a substantial and dynamic source of structural variation. Key questions going forward include how and how much new transposition events affect human health and disease.
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Affiliation(s)
- Kathleen H Burns
- Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
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Novikov A, Smyshlyaev G, Novikova O. Evolutionary history of LTR retrotransposon chromodomains in plants. INTERNATIONAL JOURNAL OF PLANT GENOMICS 2012; 2012:874743. [PMID: 22611377 PMCID: PMC3350952 DOI: 10.1155/2012/874743] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2011] [Revised: 01/27/2012] [Accepted: 02/12/2012] [Indexed: 05/25/2023]
Abstract
Chromodomain-containing LTR retrotransposons are one of the most successful groups of mobile elements in plant genomes. Previously, we demonstrated that two types of chromodomains (CHDs) are carried by plant LTR retrotransposons. Chromodomains from group I (CHD_I) were detected only in Tcn1-like LTR retrotransposons from nonseed plants such as mosses (including the model moss species Physcomitrella) and lycophytes (the Selaginella species). LTR retrotransposon chromodomains from group II (CHD_II) have been described from a wide range of higher plants. In the present study, we performed computer-based mining of plant LTR retrotransposon CHDs from diverse plants with an emphasis on spike-moss Selaginella. Our extended comparative and phylogenetic analysis demonstrated that two types of CHDs are present only in the Selaginella genome, which puts this species in a unique position among plants. It appears that a transition from CHD_I to CHD_II and further diversification occurred in the evolutionary history of plant LTR retrotransposons at approximately 400 MYA and most probably was associated with the evolution of chromatin organization.
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Affiliation(s)
- Anton Novikov
- Laboratory of Molecular Genetic Systems, Institute of Cytology and Genetics, Novosibirsk, 630090, Russia
| | - Georgiy Smyshlyaev
- Department of Natural Sciences, Novosibirsk State University, Novosibirsk, 630090, Russia
| | - Olga Novikova
- Department of Plant Pathology, University of Kentucky, Lexington, KY 40546, USA
- Department of Biological Sciences, University at Albany, Life Sciences Building 2061, 1400 Washington Avenue, Albany, NY 12222, USA
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Beck CR, Garcia-Perez JL, Badge RM, Moran JV. LINE-1 elements in structural variation and disease. Annu Rev Genomics Hum Genet 2011; 12:187-215. [PMID: 21801021 DOI: 10.1146/annurev-genom-082509-141802] [Citation(s) in RCA: 394] [Impact Index Per Article: 30.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The completion of the human genome reference sequence ushered in a new era for the study and discovery of human transposable elements. It now is undeniable that transposable elements, historically dismissed as junk DNA, have had an instrumental role in sculpting the structure and function of our genomes. In particular, long interspersed element-1 (LINE-1 or L1) and short interspersed elements (SINEs) continue to affect our genome, and their movement can lead to sporadic cases of disease. Here, we briefly review the types of transposable elements present in the human genome and their mechanisms of mobility. We next highlight how advances in DNA sequencing and genomic technologies have enabled the discovery of novel retrotransposons in individual genomes. Finally, we discuss how L1-mediated retrotransposition events impact human genomes.
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Affiliation(s)
- Christine R Beck
- Department of Human Genetics, University of MIchigan Medical School, Ann Arbor, Michigan 48109-5618, USA.
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46
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Hedges DJ, Belancio VP. Restless genomes humans as a model organism for understanding host-retrotransposable element dynamics. ADVANCES IN GENETICS 2011; 73:219-62. [PMID: 21310298 DOI: 10.1016/b978-0-12-380860-8.00006-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Since their initial discovery in maize, there have been various attempts to categorize the relationship between transposable elements (TEs) and their host organisms. These have ranged from TEs being selfish parasites to their role as essential, functional components of organismal biology. Research over the past several decades has, in many respects, only served to complicate the issue even further. On the one hand, investigators have amassed substantial evidence concerning the negative effects that TE-mutagenic activity can have on host genomes and organismal fitness. On the other hand, we find an increasing number of examples, across several taxa, of TEs being incorporated into functional biological roles for their host organism. Some 45% of our own genomes are comprised of TE copies. While many of these copies are dormant, having lost their ability to mobilize, several lineages continue to actively proliferate in modern human populations. With its complement of ancestral and active TEs, the human genome exhibits key aspects of the host-TE dynamic that has played out since early on in organismal evolution. In this review, we examine what insights the particularly well-characterized human system can provide regarding the nature of the host-TE interaction.
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Affiliation(s)
- Dale J Hedges
- Hussman Institute for Human Genomics, Dr. John T. Macdonald Foundation Department of Human Genetics, Miller School of Medicine, University of Miami, Miami, Florida, USA
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47
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Wagstaff BJ, Barnerβoi M, Roy-Engel AM. Evolutionary conservation of the functional modularity of primate and murine LINE-1 elements. PLoS One 2011; 6:e19672. [PMID: 21572950 PMCID: PMC3091869 DOI: 10.1371/journal.pone.0019672] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2011] [Accepted: 04/03/2011] [Indexed: 11/18/2022] Open
Abstract
LINE-1 (L1) retroelements emerged in mammalian genomes over 80 million years ago with a few dominant subfamilies amplifying over discrete time periods that led to distinct human and mouse L1 lineages. We evaluated the functional conservation of L1 sequences by comparing retrotransposition rates of chimeric human-rodent L1 constructs to their parental L1 counterparts. Although amino acid conservation varies from ∼35% to 63% for the L1 ORF1p and ORF2p, most human and mouse L1 sequences can be functionally exchanged. Replacing either ORF1 or ORF2 to create chimeric human-mouse L1 elements did not adversely affect retrotransposition. The mouse ORF2p retains retrotransposition-competency to support both Alu and L1 mobilization when any of the domain sequences we evaluated were substituted with human counterparts. However, the substitution of portions of the mouse cys-domain into the human ORF2p reduces both L1 retrotransposition and Alu trans-mobilization by 200–1000 fold. The observed loss of ORF2p function is independent of the endonuclease or reverse transcriptase activities of ORF2p and RNA interaction required for reverse transcription. In addition, the loss of function is physically separate from the cysteine-rich motif sequence previously shown to be required for RNP formation. Our data suggest an additional role of the less characterized carboxy-terminus of the L1 ORF2 protein by demonstrating that this domain, in addition to mediating RNP interaction(s), provides an independent and required function for the retroelement amplification process. Our experiments show a functional modularity of most of the LINE sequences. However, divergent evolution of interactions within L1 has led to non-reciprocal incompatibilities between human and mouse ORF2 cys-domain sequences.
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Affiliation(s)
- Bradley J. Wagstaff
- Tulane Cancer Center, Department of Epidemiology, Tulane University Health Sciences Center, New Orleans, Louisiana, United States of America
| | - Miriam Barnerβoi
- Tulane Cancer Center, Department of Epidemiology, Tulane University Health Sciences Center, New Orleans, Louisiana, United States of America
| | - Astrid M. Roy-Engel
- Tulane Cancer Center, Department of Epidemiology, Tulane University Health Sciences Center, New Orleans, Louisiana, United States of America
- * E-mail:
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Affiliation(s)
- Miriam K Konkel
- Department of Biological Sciences, Louisiana State University, 202 Life Sciences Bldg., Baton Rouge, LA 70803, USA
| | - Jerilyn A Walker
- Department of Biological Sciences, Louisiana State University, 202 Life Sciences Bldg., Baton Rouge, LA 70803, USA
| | - Mark A Batzer
- Department of Biological Sciences, Louisiana State University, 202 Life Sciences Bldg., Baton Rouge, LA 70803, USA
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49
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Epigenetic control of retrotransposon expression in human embryonic stem cells. Mol Cell Biol 2010; 31:300-16. [PMID: 21041477 DOI: 10.1128/mcb.00561-10] [Citation(s) in RCA: 103] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Long interspersed element 1s (LINE-1s or L1s) are a family of non-long-terminal-repeat retrotransposons that predominate in the human genome. Active LINE-1 elements encode proteins required for their mobilization. L1-encoded proteins also act in trans to mobilize short interspersed elements (SINEs), such as Alu elements. L1 and Alu insertions have been implicated in many human diseases, and their retrotransposition provides an ongoing source of human genetic diversity. L1/Alu elements are expected to ensure their transmission to subsequent generations by retrotransposing in germ cells or during early embryonic development. Here, we determined that several subfamilies of Alu elements are expressed in undifferentiated human embryonic stem cells (hESCs) and that most expressed Alu elements are active elements. We also exploited expression from the L1 antisense promoter to map expressed elements in hESCs. Remarkably, we found that expressed Alu elements are enriched in the youngest subfamily, Y, and that expressed L1s are mostly located within genes, suggesting an epigenetic control of retrotransposon expression in hESCs. Together, these data suggest that distinct subsets of active L1/Alu elements are expressed in hESCs and that the degree of somatic mosaicism attributable to L1 insertions during early development may be higher than previously anticipated.
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50
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LINE-1 retrotransposition activity in human genomes. Cell 2010; 141:1159-70. [PMID: 20602998 DOI: 10.1016/j.cell.2010.05.021] [Citation(s) in RCA: 438] [Impact Index Per Article: 31.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2010] [Revised: 03/23/2010] [Accepted: 05/13/2010] [Indexed: 01/23/2023]
Abstract
Highly active (i.e., "hot") long interspersed element-1 (LINE-1 or L1) sequences comprise the bulk of retrotransposition activity in the human genome; however, the abundance of hot L1s in the human population remains largely unexplored. Here, we used a fosmid-based, paired-end DNA sequencing strategy to identify 68 full-length L1s that are differentially present among individuals but are absent from the human genome reference sequence. The majority of these L1s were highly active in a cultured cell retrotransposition assay. Genotyping 26 elements revealed that two L1s are only found in Africa and that two more are absent from the H952 subset of the Human Genome Diversity Panel. Therefore, these results suggest that hot L1s are more abundant in the human population than previously appreciated, and that ongoing L1 retrotransposition continues to be a major source of interindividual genetic variation.
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