1
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Mendez-Dorantes C, Burns KH. LINE-1 retrotransposition and its deregulation in cancers: implications for therapeutic opportunities. Genes Dev 2023; 37:948-967. [PMID: 38092519 PMCID: PMC10760644 DOI: 10.1101/gad.351051.123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2023]
Abstract
Long interspersed element 1 (LINE-1) is the only protein-coding transposon that is active in humans. LINE-1 propagates in the genome using RNA intermediates via retrotransposition. This activity has resulted in LINE-1 sequences occupying approximately one-fifth of our genome. Although most copies of LINE-1 are immobile, ∼100 copies are retrotransposition-competent. Retrotransposition is normally limited via epigenetic silencing, DNA repair, and other host defense mechanisms. In contrast, LINE-1 overexpression and retrotransposition are hallmarks of cancers. Here, we review mechanisms of LINE-1 regulation and how LINE-1 may promote genetic heterogeneity in tumors. Finally, we discuss therapeutic strategies to exploit LINE-1 biology in cancers.
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Affiliation(s)
- Carlos Mendez-Dorantes
- Department of Pathology, Dana-Farber Cancer Institute, Boston, Massachusetts 02115, USA;
- Department of Pathology, Harvard Medical School, Boston, Massachusetts 02115, USA
- Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, Massachusetts 02142, USA
| | - Kathleen H Burns
- Department of Pathology, Dana-Farber Cancer Institute, Boston, Massachusetts 02115, USA;
- Department of Pathology, Harvard Medical School, Boston, Massachusetts 02115, USA
- Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, Massachusetts 02142, USA
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2
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Batcher K, Varney S, Raudsepp T, Jevit M, Dickinson P, Jagannathan V, Leeb T, Bannasch D. Ancient segmentally duplicated LCORL retrocopies in equids. PLoS One 2023; 18:e0286861. [PMID: 37289743 PMCID: PMC10249811 DOI: 10.1371/journal.pone.0286861] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Accepted: 05/25/2023] [Indexed: 06/10/2023] Open
Abstract
LINE-1 is an active transposable element encoding proteins capable of inserting host gene retrocopies, resulting in retro-copy number variants (retroCNVs) between individuals. Here, we performed retroCNV discovery using 86 equids and identified 437 retrocopy insertions. Only 5 retroCNVs were shared between horses and other equids, indicating that the majority of retroCNVs inserted after the species diverged. A large number (17-35 copies) of segmentally duplicated Ligand Dependent Nuclear Receptor Corepressor Like (LCORL) retrocopies were present in all equids but absent from other extant perissodactyls. The majority of LCORL transcripts in horses and donkeys originate from the retrocopies. The initial LCORL retrotransposition occurred 18 million years ago (17-19 95% CI), which is coincident with the increase in body size, reduction in digit number, and changes in dentition that characterized equid evolution. Evolutionary conservation of the LCORL retrocopy segmental amplification in the Equidae family, high expression levels and the ancient timeline for LCORL retrotransposition support a functional role for this structural variant.
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Affiliation(s)
- Kevin Batcher
- Department of Population Health and Reproduction, University of California Davis, Davis, CA, United States of America
| | - Scarlett Varney
- Department of Population Health and Reproduction, University of California Davis, Davis, CA, United States of America
| | - Terje Raudsepp
- Veterinary Integrative Biosciences, School of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas, United States of America
| | - Matthew Jevit
- Veterinary Integrative Biosciences, School of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas, United States of America
| | - Peter Dickinson
- Department of Surgical and Radiological Sciences, University of California Davis, Davis, CA, United States of America
| | - Vidhya Jagannathan
- Institute of Genetics, Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Tosso Leeb
- Institute of Genetics, Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Danika Bannasch
- Department of Population Health and Reproduction, University of California Davis, Davis, CA, United States of America
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3
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McKerrow W, Kagermazova L, Doudican N, Frazzette N, Kaparos E, Evans SA, Rocha A, Sedivy JM, Neretti N, Carucci J, Boeke J, Fenyö D. LINE-1 retrotransposon expression in cancerous, epithelial and neuronal cells revealed by 5' single-cell RNA-Seq. Nucleic Acids Res 2023; 51:2033-2045. [PMID: 36744437 PMCID: PMC10018344 DOI: 10.1093/nar/gkad049] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Revised: 01/11/2023] [Accepted: 01/17/2023] [Indexed: 02/07/2023] Open
Abstract
LINE-1 retrotransposons are sequences capable of copying themselves to new genomic loci via an RNA intermediate. New studies implicate LINE-1 in a range of diseases, especially in the context of aging, but without an accurate understanding of where and when LINE-1 is expressed, a full accounting of its role in health and disease is not possible. We therefore developed a method-5' scL1seq-that makes use of a widely available library preparation method (10x Genomics 5' single cell RNA-seq) to measure LINE-1 expression in tens of thousands of single cells. We recapitulated the known pattern of LINE-1 expression in tumors-present in cancer cells, absent from immune cells-and identified hitherto undescribed LINE-1 expression in human epithelial cells and mouse hippocampal neurons. In both cases, we saw a modest increase with age, supporting recent research connecting LINE-1 to age related diseases.
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Affiliation(s)
- Wilson McKerrow
- Institute for Systems Genetics, NYU Langone Health, New York, NY, USA
- Department of Biochemistry and Molecular Pharmacology, NYU Langone Health, New York, NY, USA
| | - Larisa Kagermazova
- Institute for Systems Genetics, NYU Langone Health, New York, NY, USA
- Department of Biochemistry and Molecular Pharmacology, NYU Langone Health, New York, NY, USA
| | - Nicole Doudican
- Ronald O. Perelman Department of Dermatology, NYU Langone Health, New York, NY, USA
| | - Nicholas Frazzette
- Ronald O. Perelman Department of Dermatology, NYU Langone Health, New York, NY, USA
| | - Efiyenia Ismini Kaparos
- Institute for Systems Genetics, NYU Langone Health, New York, NY, USA
- Department of Biochemistry and Molecular Pharmacology, NYU Langone Health, New York, NY, USA
| | - Shane A Evans
- Center for Computational Molecular Biology, Brown University, Providence, RI, USA
- Department of Molecular Biology, Cell Biology, and Biochemistry, Brown University, Providence, RI, USA
| | - Azucena Rocha
- Center for Computational Molecular Biology, Brown University, Providence, RI, USA
- Department of Molecular Biology, Cell Biology, and Biochemistry, Brown University, Providence, RI, USA
| | - John M Sedivy
- Department of Molecular Biology, Cell Biology, and Biochemistry, Brown University, Providence, RI, USA
- Center on the Biology of Aging, Brown University, Providence, RI, USA
| | - Nicola Neretti
- Center for Computational Molecular Biology, Brown University, Providence, RI, USA
- Department of Molecular Biology, Cell Biology, and Biochemistry, Brown University, Providence, RI, USA
| | - John Carucci
- Ronald O. Perelman Department of Dermatology, NYU Langone Health, New York, NY, USA
| | - Jef D Boeke
- Institute for Systems Genetics, NYU Langone Health, New York, NY, USA
- Department of Biochemistry and Molecular Pharmacology, NYU Langone Health, New York, NY, USA
- Department of Biomedical Engineering, NYU Tandon School of Engineering, Brooklyn,NY11201, USA
| | - David Fenyö
- Institute for Systems Genetics, NYU Langone Health, New York, NY, USA
- Department of Biochemistry and Molecular Pharmacology, NYU Langone Health, New York, NY, USA
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4
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Gerdes P, Lim SM, Ewing AD, Larcombe MR, Chan D, Sanchez-Luque FJ, Walker L, Carleton AL, James C, Knaupp AS, Carreira PE, Nefzger CM, Lister R, Richardson SR, Polo JM, Faulkner GJ. Retrotransposon instability dominates the acquired mutation landscape of mouse induced pluripotent stem cells. Nat Commun 2022; 13:7470. [PMID: 36463236 PMCID: PMC9719517 DOI: 10.1038/s41467-022-35180-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Accepted: 11/22/2022] [Indexed: 12/04/2022] Open
Abstract
Induced pluripotent stem cells (iPSCs) can in principle differentiate into any cell of the body, and have revolutionized biomedical research and regenerative medicine. Unlike their human counterparts, mouse iPSCs (miPSCs) are reported to silence transposable elements and prevent transposable element-mediated mutagenesis. Here we apply short-read or Oxford Nanopore Technologies long-read genome sequencing to 38 bulk miPSC lines reprogrammed from 10 parental cell types, and 18 single-cell miPSC clones. While single nucleotide variants and structural variants restricted to miPSCs are rare, we find 83 de novo transposable element insertions, including examples intronic to Brca1 and Dmd. LINE-1 retrotransposons are profoundly hypomethylated in miPSCs, beyond other transposable elements and the genome overall, and harbor alternative protein-coding gene promoters. We show that treatment with the LINE-1 inhibitor lamivudine does not hinder reprogramming and efficiently blocks endogenous retrotransposition, as detected by long-read genome sequencing. These experiments reveal the complete spectrum and potential significance of mutations acquired by miPSCs.
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Affiliation(s)
- Patricia Gerdes
- grid.1003.20000 0000 9320 7537Mater Research Institute - University of Queensland, TRI Building, Woolloongabba, QLD 4102 Australia
| | - Sue Mei Lim
- grid.1002.30000 0004 1936 7857Department of Anatomy & Developmental Biology, Monash University, Melbourne, VIC 3800 Australia ,grid.1002.30000 0004 1936 7857Development and Stem Cells Program, Monash Biomedicine Discovery Institute, Melbourne, VIC 3800 Australia ,grid.1002.30000 0004 1936 7857Australian Regenerative Medicine Institute, Monash University, Melbourne, VIC 3800 Australia
| | - Adam D. Ewing
- grid.1003.20000 0000 9320 7537Mater Research Institute - University of Queensland, TRI Building, Woolloongabba, QLD 4102 Australia
| | - Michael R. Larcombe
- grid.1002.30000 0004 1936 7857Department of Anatomy & Developmental Biology, Monash University, Melbourne, VIC 3800 Australia ,grid.1002.30000 0004 1936 7857Development and Stem Cells Program, Monash Biomedicine Discovery Institute, Melbourne, VIC 3800 Australia ,grid.1002.30000 0004 1936 7857Australian Regenerative Medicine Institute, Monash University, Melbourne, VIC 3800 Australia
| | - Dorothy Chan
- grid.1003.20000 0000 9320 7537Mater Research Institute - University of Queensland, TRI Building, Woolloongabba, QLD 4102 Australia
| | - Francisco J. Sanchez-Luque
- grid.1003.20000 0000 9320 7537Mater Research Institute - University of Queensland, TRI Building, Woolloongabba, QLD 4102 Australia ,grid.418805.00000 0004 0500 8423GENYO. Pfizer-University of Granada-Andalusian Government Centre for Genomics and Oncological Research, PTS, Granada, 18016 Spain
| | - Lucinda Walker
- grid.1003.20000 0000 9320 7537Mater Research Institute - University of Queensland, TRI Building, Woolloongabba, QLD 4102 Australia
| | - Alexander L. Carleton
- grid.1003.20000 0000 9320 7537Mater Research Institute - University of Queensland, TRI Building, Woolloongabba, QLD 4102 Australia
| | - Cini James
- grid.1003.20000 0000 9320 7537Mater Research Institute - University of Queensland, TRI Building, Woolloongabba, QLD 4102 Australia
| | - Anja S. Knaupp
- grid.1002.30000 0004 1936 7857Department of Anatomy & Developmental Biology, Monash University, Melbourne, VIC 3800 Australia ,grid.1002.30000 0004 1936 7857Development and Stem Cells Program, Monash Biomedicine Discovery Institute, Melbourne, VIC 3800 Australia ,grid.1002.30000 0004 1936 7857Australian Regenerative Medicine Institute, Monash University, Melbourne, VIC 3800 Australia
| | - Patricia E. Carreira
- grid.1003.20000 0000 9320 7537Mater Research Institute - University of Queensland, TRI Building, Woolloongabba, QLD 4102 Australia
| | - Christian M. Nefzger
- grid.1002.30000 0004 1936 7857Department of Anatomy & Developmental Biology, Monash University, Melbourne, VIC 3800 Australia ,grid.1002.30000 0004 1936 7857Development and Stem Cells Program, Monash Biomedicine Discovery Institute, Melbourne, VIC 3800 Australia ,grid.1002.30000 0004 1936 7857Australian Regenerative Medicine Institute, Monash University, Melbourne, VIC 3800 Australia
| | - Ryan Lister
- grid.1012.20000 0004 1936 7910Australian Research Council Centre of Excellence in Plant Energy Biology, School of Molecular Sciences, The University of Western Australia, Perth, WA 6009 Australia ,grid.431595.f0000 0004 0469 0045Harry Perkins Institute of Medical Research, Perth, WA 6009 Australia
| | - Sandra R. Richardson
- grid.1003.20000 0000 9320 7537Mater Research Institute - University of Queensland, TRI Building, Woolloongabba, QLD 4102 Australia
| | - Jose M. Polo
- grid.1002.30000 0004 1936 7857Department of Anatomy & Developmental Biology, Monash University, Melbourne, VIC 3800 Australia ,grid.1002.30000 0004 1936 7857Development and Stem Cells Program, Monash Biomedicine Discovery Institute, Melbourne, VIC 3800 Australia ,grid.1002.30000 0004 1936 7857Australian Regenerative Medicine Institute, Monash University, Melbourne, VIC 3800 Australia ,grid.1010.00000 0004 1936 7304Adelaide Centre for Epigenetics and The South Australian Immunogenomics Cancer Institute, Faculty of Health and Medical Sciences, The University of Adelaide, Adelaide, SA 5005 Australia
| | - Geoffrey J. Faulkner
- grid.1003.20000 0000 9320 7537Mater Research Institute - University of Queensland, TRI Building, Woolloongabba, QLD 4102 Australia ,grid.1003.20000 0000 9320 7537Queensland Brain Institute, University of Queensland, Brisbane, QLD 4072 Australia
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5
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Batcher K, Varney S, York D, Blacksmith M, Kidd JM, Rebhun R, Dickinson P, Bannasch D. Recent, full-length gene retrocopies are common in canids. Genome Res 2022; 32:1602-1611. [PMID: 35961775 PMCID: PMC9435743 DOI: 10.1101/gr.276828.122] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Accepted: 07/19/2022] [Indexed: 02/03/2023]
Abstract
Gene retrocopies arise from the reverse transcription and insertion into the genome of processed mRNA transcripts. Although many retrocopies have acquired mutations that render them functionally inactive, most mammals retain active LINE-1 sequences capable of producing new retrocopies. New retrocopies, referred to as retro copy number variants (retroCNVs), may not be identified by standard variant calling techniques in high-throughput sequencing data. Although multiple functional FGF4 retroCNVs have been associated with skeletal dysplasias in dogs, the full landscape of canid retroCNVs has not been characterized. Here, retroCNV discovery was performed on a whole-genome sequencing data set of 293 canids from 76 breeds. We identified retroCNV parent genes via the presence of mRNA-specific 30-mers, and then identified retroCNV insertion sites through discordant read analysis. In total, we resolved insertion sites for 1911 retroCNVs from 1179 parent genes, 1236 of which appeared identical to their parent genes. Dogs had on average 54.1 total retroCNVs and 1.4 private retroCNVs. We found evidence of expression in testes for 12% (14/113) of the retroCNVs identified in six Golden Retrievers, including four chimeric transcripts, and 97 retroCNVs also had significantly elevated F ST across dog breeds, possibly indicating selection. We applied our approach to a subset of human genomes and detected an average of 4.2 retroCNVs per sample, highlighting a 13-fold relative increase of retroCNV frequency in dogs. Particularly in canids, retroCNVs are a largely unexplored source of genetic variation that can contribute to genome plasticity and that should be considered when investigating traits and diseases.
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Affiliation(s)
- Kevin Batcher
- Department of Population Health and Reproduction, University of California, Davis, Davis, California 95616, USA
| | - Scarlett Varney
- Department of Population Health and Reproduction, University of California, Davis, Davis, California 95616, USA
| | - Daniel York
- Department of Surgical and Radiological Sciences, University of California, Davis, Davis, California 95616, USA
| | - Matthew Blacksmith
- Department of Human Genetics, University of Michigan Medical School, Ann Arbor, Michigan 48109, USA
| | - Jeffrey M Kidd
- Department of Human Genetics, University of Michigan Medical School, Ann Arbor, Michigan 48109, USA
- Department of Computational Medicine and Bioinformatics, University of Michigan Medical School, Ann Arbor, Michigan 48109, USA
| | - Robert Rebhun
- Department of Surgical and Radiological Sciences, University of California, Davis, Davis, California 95616, USA
| | - Peter Dickinson
- Department of Surgical and Radiological Sciences, University of California, Davis, Davis, California 95616, USA
| | - Danika Bannasch
- Department of Population Health and Reproduction, University of California, Davis, Davis, California 95616, USA
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6
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Pascarella G, Hon CC, Hashimoto K, Busch A, Luginbühl J, Parr C, Hin Yip W, Abe K, Kratz A, Bonetti A, Agostini F, Severin J, Murayama S, Suzuki Y, Gustincich S, Frith M, Carninci P. Recombination of repeat elements generates somatic complexity in human genomes. Cell 2022; 185:3025-3040.e6. [DOI: 10.1016/j.cell.2022.06.032] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Revised: 03/30/2022] [Accepted: 06/16/2022] [Indexed: 12/14/2022]
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7
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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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8
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Chesnokova E, Beletskiy A, Kolosov P. The Role of Transposable Elements of the Human Genome in Neuronal Function and Pathology. Int J Mol Sci 2022; 23:5847. [PMID: 35628657 PMCID: PMC9148063 DOI: 10.3390/ijms23105847] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Revised: 05/17/2022] [Accepted: 05/19/2022] [Indexed: 12/13/2022] Open
Abstract
Transposable elements (TEs) have been extensively studied for decades. In recent years, the introduction of whole-genome and whole-transcriptome approaches, as well as single-cell resolution techniques, provided a breakthrough that uncovered TE involvement in host gene expression regulation underlying multiple normal and pathological processes. Of particular interest is increased TE activity in neuronal tissue, and specifically in the hippocampus, that was repeatedly demonstrated in multiple experiments. On the other hand, numerous neuropathologies are associated with TE dysregulation. Here, we provide a comprehensive review of literature about the role of TEs in neurons published over the last three decades. The first chapter of the present review describes known mechanisms of TE interaction with host genomes in general, with the focus on mammalian and human TEs; the second chapter provides examples of TE exaptation in normal neuronal tissue, including TE involvement in neuronal differentiation and plasticity; and the last chapter lists TE-related neuropathologies. We sought to provide specific molecular mechanisms of TE involvement in neuron-specific processes whenever possible; however, in many cases, only phenomenological reports were available. This underscores the importance of further studies in this area.
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Affiliation(s)
- Ekaterina Chesnokova
- Laboratory of Cellular Neurobiology of Learning, Institute of Higher Nervous Activity and Neurophysiology of the Russian Academy of Sciences, 117485 Moscow, Russia; (A.B.); (P.K.)
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9
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Keegan RM, Talbot LR, Chang YH, Metzger MJ, Dubnau J. Intercellular viral spread and intracellular transposition of Drosophila gypsy. PLoS Genet 2021; 17:e1009535. [PMID: 33886543 PMCID: PMC8096092 DOI: 10.1371/journal.pgen.1009535] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Revised: 05/04/2021] [Accepted: 04/06/2021] [Indexed: 01/12/2023] Open
Abstract
It has become increasingly clear that retrotransposons (RTEs) are more widely expressed in somatic tissues than previously appreciated. RTE expression has been implicated in a myriad of biological processes ranging from normal development and aging, to age related diseases such as cancer and neurodegeneration. Long Terminal Repeat (LTR)-RTEs are evolutionary ancestors to, and share many features with, exogenous retroviruses. In fact, many organisms contain endogenous retroviruses (ERVs) derived from exogenous retroviruses that integrated into the germ line. These ERVs are inherited in Mendelian fashion like RTEs, and some retain the ability to transmit between cells like viruses, while others develop the ability to act as RTEs. The process of evolutionary transition between LTR-RTE and retroviruses is thought to involve multiple steps by which the element loses or gains the ability to transmit copies between cells versus the ability to replicate intracellularly. But, typically, these two modes of transmission are incompatible because they require assembly in different sub-cellular compartments. Like murine IAP/IAP-E elements, the gypsy family of retroelements in arthropods appear to sit along this evolutionary transition. Indeed, there is some evidence that gypsy may exhibit retroviral properties. Given that gypsy elements have been found to actively mobilize in neurons and glial cells during normal aging and in models of neurodegeneration, this raises the question of whether gypsy replication in somatic cells occurs via intracellular retrotransposition, intercellular viral spread, or some combination of the two. These modes of replication in somatic tissues would have quite different biological implications. Here, we demonstrate that Drosophila gypsy is capable of both cell-associated and cell-free viral transmission between cultured S2 cells of somatic origin. Further, we demonstrate that the ability of gypsy to move between cells is dependent upon a functional copy of its viral envelope protein. This argues that the gypsy element has transitioned from an RTE into a functional endogenous retrovirus with the acquisition of its envelope gene. On the other hand, we also find that intracellular retrotransposition of the same genomic copy of gypsy can occur in the absence of the Env protein. Thus, gypsy exhibits both intracellular retrotransposition and intercellular viral transmission as modes of replicating its genome.
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Affiliation(s)
- Richard M. Keegan
- Program in Neuroscience, Department of Neurobiology and Behavior, Stony Brook University, New York City, New York, United States of America
| | - Lillian R. Talbot
- Medical Scientist Training Program, Department of Neurobiology and Behavior, Stony Brook University, New York City, New York, United States of America
| | - Yung-Heng Chang
- Department of Anesthesiology, Stony Brook School of Medicine, New York City, New York, United States of America
| | - Michael J. Metzger
- Pacific Northwest Research Institute, Seattle, Washington, United States of America
| | - Josh Dubnau
- Program in Neuroscience, Department of Neurobiology and Behavior, Stony Brook University, New York City, New York, United States of America
- Department of Anesthesiology, Stony Brook School of Medicine, New York City, New York, United States of America
- Pacific Northwest Research Institute, Seattle, Washington, United States of America
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10
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Ewing AD, Smits N, Sanchez-Luque FJ, Faivre J, Brennan PM, Richardson SR, Cheetham SW, Faulkner GJ. Nanopore Sequencing Enables Comprehensive Transposable Element Epigenomic Profiling. Mol Cell 2020; 80:915-928.e5. [PMID: 33186547 DOI: 10.1016/j.molcel.2020.10.024] [Citation(s) in RCA: 97] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 10/14/2020] [Accepted: 10/15/2020] [Indexed: 12/12/2022]
Abstract
Transposable elements (TEs) drive genome evolution and are a notable source of pathogenesis, including cancer. While CpG methylation regulates TE activity, the locus-specific methylation landscape of mobile human TEs has to date proven largely inaccessible. Here, we apply new computational tools and long-read nanopore sequencing to directly infer CpG methylation of novel and extant TE insertions in hippocampus, heart, and liver, as well as paired tumor and non-tumor liver. As opposed to an indiscriminate stochastic process, we find pronounced demethylation of young long interspersed element 1 (LINE-1) retrotransposons in cancer, often distinct to the adjacent genome and other TEs. SINE-VNTR-Alu (SVA) retrotransposons, including their internal tandem repeat-associated CpG island, are near-universally methylated. We encounter allele-specific TE methylation and demethylation of aberrantly expressed young LINE-1s in normal tissues. Finally, we recover the complete sequences of tumor-specific LINE-1 insertions and their retrotransposition hallmarks, demonstrating how long-read sequencing can simultaneously survey the epigenome and detect somatic TE mobilization.
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Affiliation(s)
- Adam D Ewing
- Mater Research Institute, University of Queensland, Woolloongabba, QLD 4102, Australia.
| | - Nathan Smits
- Mater Research Institute, University of Queensland, Woolloongabba, QLD 4102, Australia
| | - 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 Molecular Medicine (IGMM), University of Edinburgh, Western General Hospital, Edinburgh EH4 2XU, UK
| | - Jamila Faivre
- INSERM, U1193, Paul-Brousse University Hospital, Hepatobiliary Centre, Villejuif 94800, France
| | - Paul M Brennan
- Translational Neurosurgery, Centre for Clinical Brain Sciences, Edinburgh EH16 4SB, UK
| | - Sandra R Richardson
- Mater Research Institute, University of Queensland, Woolloongabba, QLD 4102, Australia
| | - Seth W Cheetham
- Mater Research Institute, University of Queensland, Woolloongabba, QLD 4102, Australia.
| | - Geoffrey J Faulkner
- Mater Research Institute, University of Queensland, Woolloongabba, QLD 4102, Australia; Queensland Brain Institute, University of Queensland, St. Lucia, QLD 4067, Australia.
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11
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DNA Associated with Circulating Exosomes as a Biomarker for Glioma. Genes (Basel) 2020; 11:genes11111276. [PMID: 33137926 PMCID: PMC7692052 DOI: 10.3390/genes11111276] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Revised: 10/16/2020] [Accepted: 10/26/2020] [Indexed: 02/07/2023] Open
Abstract
Cancerous and non-cancerous cells secrete exosomes, a type of nanovesicle known to carry the molecular signature of the parent for intercellular communications. Exosomes secreted by tumor cells carry abnormal DNA, RNA, and protein molecules that reflect the cancerous status. DNA is the master molecule that ultimately affects the function of RNA and proteins. Aberrations in DNA can potentially lead a cell to malignancy. Deviant quantities and the differential sequences of exosomal DNA are useful characteristics as cancer biomarkers. Since these alterations are either associated with specific stages of cancer or caused due to a clinical treatment, exosomal DNA is valuable as a diagnostic, prognostic, predictive, and therapeutic-intervention response biomarker. Notably, the exosomes can cross an intact blood–brain barrier and anatomical compartments by transcytosis. As such, the cancer-specific trademark molecules can be detected in systemic blood circulation and other body fluids, including cerebrospinal fluid, with non-invasive or minimally invasive procedures. This comprehensive review highlights the cancer-specific modulations of DNA associated with circulating exosomes that are beneficial as glioma biomarkers.
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12
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LeBien J, McCollam G, Atallah J. An in silico model of LINE-1-mediated neoplastic evolution. Bioinformatics 2020; 36:4144-4153. [PMID: 32365170 DOI: 10.1093/bioinformatics/btaa279] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Revised: 04/19/2020] [Accepted: 04/24/2020] [Indexed: 11/13/2022] Open
Abstract
MOTIVATION Recent research has uncovered roles for transposable elements (TEs) in multiple evolutionary processes, ranging from somatic evolution in cancer to putatively adaptive germline evolution across species. Most models of TE population dynamics, however, have not incorporated actual genome sequence data. The effect of site integration preferences of specific TEs on evolutionary outcomes and the effects of different selection regimes on TE dynamics in a specific genome are unknown. We present a stochastic model of LINE-1 (L1) transposition in human cancer. This system was chosen because the transposition of L1 elements is well understood, the population dynamics of cancer tumors has been modeled extensively, and the role of L1 elements in cancer progression has garnered interest in recent years. RESULTS Our model predicts that L1 retrotransposition (RT) can play either advantageous or deleterious roles in tumor progression, depending on the initial lesion size, L1 insertion rate and tumor driver genes. Small changes in the RT rate or set of driver tumor-suppressor genes (TSGs) were observed to alter the dynamics of tumorigenesis. We found high variation in the density of L1 target sites across human protein-coding genes. We also present an analysis, across three cancer types, of the frequency of homozygous TSG disruption in wild-type hosts compared to those with an inherited driver allele. AVAILABILITY AND IMPLEMENTATION Source code is available at https://github.com/atallah-lab/neoplastic-evolution. CONTACT jlebien@uno.edu. SUPPLEMENTARY INFORMATION Supplementary data are available at Bioinformatics online.
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Affiliation(s)
- Jack LeBien
- Department of Biological Sciences, The University of New, Orleans, New Orleans, LA 70148, USA
| | - Gerald McCollam
- Advanced Academic Programs, John Hopkins University, Baltimore, MD 21218, USA
| | - Joel Atallah
- Department of Biological Sciences, The University of New, Orleans, New Orleans, LA 70148, USA
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13
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Burns KH. Our Conflict with Transposable Elements and Its Implications for Human Disease. ANNUAL REVIEW OF PATHOLOGY-MECHANISMS OF DISEASE 2020; 15:51-70. [PMID: 31977294 DOI: 10.1146/annurev-pathmechdis-012419-032633] [Citation(s) in RCA: 71] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Our genome is a historic record of successive invasions of mobile genetic elements. Like other eukaryotes, we have evolved mechanisms to limit their propagation and minimize the functional impact of new insertions. Although these mechanisms are vitally important, they are imperfect, and a handful of retroelement families remain active in modern humans. This review introduces the intrinsic functions of transposons, the tactics employed in their restraint, and the relevance of this conflict to human pathology. The most straightforward examples of disease-causing transposable elements are germline insertions that disrupt a gene and result in a monogenic disease allele. More enigmatic are the abnormal patterns of transposable element expression in disease states. Changes in transposon regulation and cellular responses to their expression have implicated these sequences in diseases as diverse as cancer, autoimmunity, and neurodegeneration. Distinguishing their epiphenomenal from their pathogenic effects may provide wholly new perspectives on our understanding of disease.
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Affiliation(s)
- Kathleen H Burns
- Department of Pathology, McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA;
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14
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Chang YH, Keegan RM, Prazak L, Dubnau J. Cellular labeling of endogenous retrovirus replication (CLEVR) reveals de novo insertions of the gypsy retrotransposable element in cell culture and in both neurons and glial cells of aging fruit flies. PLoS Biol 2019; 17:e3000278. [PMID: 31095565 PMCID: PMC6541305 DOI: 10.1371/journal.pbio.3000278] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Revised: 05/29/2019] [Accepted: 05/03/2019] [Indexed: 12/11/2022] Open
Abstract
Evidence is rapidly mounting that transposable element (TE) expression and replication may impact biology more widely than previously thought. This includes potential effects on normal physiology of somatic tissues and dysfunctional impacts in diseases associated with aging, such as cancer and neurodegeneration. Investigation of the biological impact of mobile elements in somatic cells will be greatly facilitated by the use of donor elements that are engineered to report de novo events in vivo. In multicellular organisms, reporter constructs demonstrating engineered long interspersed nuclear element (LINE-1; L1) mobilization have been in use for quite some time, and strategies similar to L1 retrotransposition reporter assays have been developed to report replication of Ty1 elements in yeast and mouse intracisternal A particle (IAP) long terminal repeat (LTR) retrotransposons in cultivated cells. We describe a novel approach termed cellular labeling of endogenous retrovirus replication (CLEVR), which reports replication of the gypsy element within specific cells in vivo in Drosophila. The gypsy-CLEVR reporter reveals gypsy replication both in cell culture and in individual neurons and glial cells of the aging adult fly. We also demonstrate that the gypsy-CLEVR replication rate is increased when the short interfering RNA (siRNA) silencing system is genetically disrupted. This CLEVR strategy makes use of universally conserved features of retroviruses and should be widely applicable to other LTR retrotransposons, endogenous retroviruses (ERVs), and exogenous retroviruses.
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Affiliation(s)
- Yung-Heng Chang
- Department of Anesthesiology, Stony Brook School of Medicine, Stony Brook, New York, United States of America
| | - Richard M. Keegan
- Program in Neuroscience, Department of Neurobiology and Behavior, Stony Brook University, Stony Brook, New York, United States of America
| | - Lisa Prazak
- Biology, Farmingdale State College, Farmingdale, New York, United States of America
| | - Josh Dubnau
- Department of Anesthesiology, Stony Brook School of Medicine, Stony Brook, New York, United States of America
- Program in Neuroscience, Department of Neurobiology and Behavior, Stony Brook University, Stony Brook, New York, United States of America
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15
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Bodea GO, McKelvey EGZ, Faulkner GJ. Retrotransposon-induced mosaicism in the neural genome. Open Biol 2019; 8:rsob.180074. [PMID: 30021882 PMCID: PMC6070720 DOI: 10.1098/rsob.180074] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Accepted: 06/21/2018] [Indexed: 12/18/2022] Open
Abstract
Over the past decade, major discoveries in retrotransposon biology have depicted the neural genome as a dynamic structure during life. In particular, the retrotransposon LINE-1 (L1) has been shown to be transcribed and mobilized in the brain. Retrotransposition in the developing brain, as well as during adult neurogenesis, provides a milieu in which neural diversity can arise. Dysregulation of retrotransposon activity may also contribute to neurological disease. Here, we review recent reports of retrotransposon activity in the brain, and discuss the temporal nature of retrotransposition and its regulation in neural cells in response to stimuli. We also put forward hypotheses regarding the significance of retrotransposons for brain development and neurological function, and consider the potential implications of this phenomenon for neuropsychiatric and neurodegenerative conditions.
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Affiliation(s)
- Gabriela O Bodea
- Mater Research Institute-University of Queensland, TRI Building, Brisbane, Queensland 4102, Australia .,Queensland Brain Institute, University of Queensland, Brisbane, Queensland 4072, Australia
| | - Eleanor G Z McKelvey
- Queensland Brain Institute, University of Queensland, Brisbane, Queensland 4072, Australia
| | - Geoffrey J Faulkner
- Mater Research Institute-University of Queensland, TRI Building, Brisbane, Queensland 4102, Australia .,Queensland Brain Institute, University of Queensland, Brisbane, Queensland 4072, Australia
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16
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Steranka JP, Tang Z, Grivainis M, Huang CRL, Payer LM, Rego FOR, Miller TLA, Galante PAF, Ramaswami S, Heguy A, Fenyö D, Boeke JD, Burns KH. Transposon insertion profiling by sequencing (TIPseq) for mapping LINE-1 insertions in the human genome. Mob DNA 2019; 10:8. [PMID: 30899333 PMCID: PMC6407172 DOI: 10.1186/s13100-019-0148-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Accepted: 01/14/2019] [Indexed: 12/14/2022] Open
Abstract
Background Transposable elements make up a significant portion of the human genome. Accurately locating these mobile DNAs is vital to understand their role as a source of structural variation and somatic mutation. To this end, laboratories have developed strategies to selectively amplify or otherwise enrich transposable element insertion sites in genomic DNA. Results Here we describe a technique, Transposon Insertion Profiling by sequencing (TIPseq), to map Long INterspersed Element 1 (LINE-1, L1) retrotransposon insertions in the human genome. This method uses vectorette PCR to amplify species-specific L1 (L1PA1) insertion sites followed by paired-end Illumina sequencing. In addition to providing a step-by-step molecular biology protocol, we offer users a guide to our pipeline for data analysis, TIPseqHunter. Our recent studies in pancreatic and ovarian cancer demonstrate the ability of TIPseq to identify invariant (fixed), polymorphic (inherited variants), as well as somatically-acquired L1 insertions that distinguish cancer genomes from a patient’s constitutional make-up. Conclusions TIPseq provides an approach for amplifying evolutionarily young, active transposable element insertion sites from genomic DNA. Our rationale and variations on this protocol may be useful to those mapping L1 and other mobile elements in complex genomes. Electronic supplementary material The online version of this article (10.1186/s13100-019-0148-5) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Jared P Steranka
- 1Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD 21205 USA.,2McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205 USA
| | - Zuojian Tang
- 3Department for Biochemistry and Molecular Pharmacology, NYU Langone Health, New York, NY 10016 USA.,4Institute for Systems Genetics, NYU Langone Health, New York, NY 10016 USA
| | - Mark Grivainis
- 3Department for Biochemistry and Molecular Pharmacology, NYU Langone Health, New York, NY 10016 USA.,4Institute for Systems Genetics, NYU Langone Health, New York, NY 10016 USA
| | - Cheng Ran Lisa Huang
- 2McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205 USA
| | - Lindsay M Payer
- 1Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD 21205 USA
| | - Fernanda O R Rego
- 5Centro de Oncologia Molecular, Hospital Sírio-Libanês, São Paulo, Brazil
| | - Thiago Luiz Araujo Miller
- 5Centro de Oncologia Molecular, Hospital Sírio-Libanês, São Paulo, Brazil.,Departamento de Bioquímica, Instituto de Química, Universidade de São Paul, São Paulo, Brazil
| | - Pedro A F Galante
- 5Centro de Oncologia Molecular, Hospital Sírio-Libanês, São Paulo, Brazil
| | - Sitharam Ramaswami
- 7Genome Technology Center, Division of Advanced Research Technologies, NYU Langone Health, New York, NY USA
| | - Adriana Heguy
- 7Genome Technology Center, Division of Advanced Research Technologies, NYU Langone Health, New York, NY USA
| | - David Fenyö
- 3Department for Biochemistry and Molecular Pharmacology, NYU Langone Health, New York, NY 10016 USA.,4Institute for Systems Genetics, NYU Langone Health, New York, NY 10016 USA
| | - Jef D Boeke
- 4Institute for Systems Genetics, NYU Langone Health, New York, NY 10016 USA
| | - Kathleen H Burns
- 1Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD 21205 USA.,2McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205 USA
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17
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Faulkner GJ, Billon V. L1 retrotransposition in the soma: a field jumping ahead. Mob DNA 2018; 9:22. [PMID: 30002735 PMCID: PMC6035798 DOI: 10.1186/s13100-018-0128-1] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Accepted: 06/27/2018] [Indexed: 12/13/2022] Open
Abstract
Retrotransposons are transposable elements (TEs) capable of "jumping" in germ, embryonic and tumor cells and, as is now clearly established, in the neuronal lineage. Mosaic TE insertions form part of a broader landscape of somatic genome variation and hold significant potential to generate phenotypic diversity, in the brain and elsewhere. At present, the LINE-1 (L1) retrotransposon family appears to be the most active autonomous TE in most mammals, based on experimental data obtained from disease-causing L1 mutations, engineered L1 reporter systems tested in cultured cells and transgenic rodents, and single-cell genomic analyses. However, the biological consequences of almost all somatic L1 insertions identified thus far remain unknown. In this review, we briefly summarize the current state-of-the-art in the field, including estimates of L1 retrotransposition rate in neurons. We bring forward the hypothesis that an extensive subset of retrotransposition-competent L1s may be de-repressed and mobile in the soma but largely inactive in the germline. We discuss recent reports of non-canonical L1-associated sequence variants in the brain and propose that the elevated L1 DNA content reported in several neurological disorders may predominantly comprise accumulated, unintegrated L1 nucleic acids, rather than somatic L1 insertions. Finally, we consider the main objectives and obstacles going forward in elucidating the biological impact of somatic retrotransposition.
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Affiliation(s)
- Geoffrey J. Faulkner
- Mater Research Institute – University of Queensland, TRI Building, Woolloongabba, QLD 4102 Australia
- School of Biomedical Sciences, University of Queensland, Brisbane, QLD 4072 Australia
- Queensland Brain Institute, University of Queensland, Brisbane, QLD 4072 Australia
| | - Victor Billon
- Queensland Brain Institute, University of Queensland, Brisbane, QLD 4072 Australia
- Biology Department, École Normale Supérieure Paris-Saclay, 61 Avenue du Président Wilson, 94230 Cachan, France
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18
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Schauer SN, Carreira PE, Shukla R, Gerhardt DJ, Gerdes P, Sanchez-Luque FJ, Nicoli P, Kindlova M, Ghisletti S, Santos AD, Rapoud D, Samuel D, Faivre J, Ewing AD, Richardson SR, Faulkner GJ. L1 retrotransposition is a common feature of mammalian hepatocarcinogenesis. Genome Res 2018; 28:639-653. [PMID: 29643204 PMCID: PMC5932605 DOI: 10.1101/gr.226993.117] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Accepted: 03/26/2018] [Indexed: 12/15/2022]
Abstract
The retrotransposon Long Interspersed Element 1 (LINE-1 or L1) is a continuing source of germline and somatic mutagenesis in mammals. Deregulated L1 activity is a hallmark of cancer, and L1 mutagenesis has been described in numerous human malignancies. We previously employed retrotransposon capture sequencing (RC-seq) to analyze hepatocellular carcinoma (HCC) samples from patients infected with hepatitis B or hepatitis C virus and identified L1 variants responsible for activating oncogenic pathways. Here, we have applied RC-seq and whole-genome sequencing (WGS) to an Abcb4 (Mdr2)-/- mouse model of hepatic carcinogenesis and demonstrated for the first time that L1 mobilization occurs in murine tumors. In 12 HCC nodules obtained from 10 animals, we validated four somatic L1 insertions by PCR and capillary sequencing, including TF subfamily elements, and one GF subfamily example. One of the TF insertions carried a 3' transduction, allowing us to identify its donor L1 and to demonstrate that this full-length TF element retained retrotransposition capacity in cultured cancer cells. Using RC-seq, we also identified eight tumor-specific L1 insertions from 25 HCC patients with a history of alcohol abuse. Finally, we used RC-seq and WGS to identify three tumor-specific L1 insertions among 10 intra-hepatic cholangiocarcinoma (ICC) patients, including one insertion traced to a donor L1 on Chromosome 22 known to be highly active in other cancers. This study reveals L1 mobilization as a common feature of hepatocarcinogenesis in mammals, demonstrating that the phenomenon is not restricted to human viral HCC etiologies and is encountered in murine liver tumors.
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Affiliation(s)
- Stephanie N Schauer
- Mater Research Institute-University of Queensland, Woolloongabba, QLD 4102, Australia
| | - Patricia E Carreira
- Mater Research Institute-University of Queensland, Woolloongabba, QLD 4102, Australia
| | - Ruchi Shukla
- Northern Institute for Cancer Research, Newcastle University, Newcastle upon Tyne NE1 7RU, United Kingdom
| | - Daniel J Gerhardt
- Mater Research Institute-University of Queensland, Woolloongabba, QLD 4102, Australia
- Invenra, Incorporated, Madison, Wisconsin 53719, USA
| | - Patricia Gerdes
- Mater Research Institute-University of Queensland, Woolloongabba, QLD 4102, Australia
| | - Francisco J Sanchez-Luque
- Mater Research Institute-University of Queensland, Woolloongabba, QLD 4102, Australia
- Department of Genomic Medicine, GENYO, Centre for Genomics and Oncological Research: Pfizer-University of Granada-Andalusian Regional Government, PTS Granada, 18016 Granada, Spain
| | - Paola Nicoli
- Department of Experimental Oncology, European Institute of Oncology, 20146 Milan, Italy
| | - Michaela Kindlova
- Mater Research Institute-University of Queensland, Woolloongabba, QLD 4102, Australia
| | | | - Alexandre Dos Santos
- INSERM, U1193, Paul-Brousse University Hospital, Hepatobiliary Centre, Villejuif 94800, France
- Université Paris-Sud, Faculté de Médecine, Villejuif 94800, France
| | - Delphine Rapoud
- INSERM, U1193, Paul-Brousse University Hospital, Hepatobiliary Centre, Villejuif 94800, France
- Université Paris-Sud, Faculté de Médecine, Villejuif 94800, France
| | - Didier Samuel
- INSERM, U1193, Paul-Brousse University Hospital, Hepatobiliary Centre, Villejuif 94800, France
- Université Paris-Sud, Faculté de Médecine, Villejuif 94800, France
| | - Jamila Faivre
- INSERM, U1193, Paul-Brousse University Hospital, Hepatobiliary Centre, Villejuif 94800, France
- Université Paris-Sud, Faculté de Médecine, Villejuif 94800, France
- Assistance Publique-Hôpitaux de Paris (AP-HP), Pôle de Biologie Médicale, Paul-Brousse University Hospital, Villejuif 94800, France
| | - Adam D Ewing
- Mater Research Institute-University of Queensland, Woolloongabba, QLD 4102, Australia
| | - Sandra R Richardson
- Mater Research Institute-University of Queensland, Woolloongabba, QLD 4102, Australia
| | - Geoffrey J Faulkner
- Mater Research Institute-University of Queensland, Woolloongabba, QLD 4102, Australia
- School of Biomedical Sciences, University of Queensland, Brisbane, QLD 4072, Australia
- Queensland Brain Institute, University of Queensland, Brisbane, QLD 4072, Australia
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19
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Suarez NA, Macia A, Muotri AR. LINE-1 retrotransposons in healthy and diseased human brain. Dev Neurobiol 2017; 78:434-455. [PMID: 29239145 DOI: 10.1002/dneu.22567] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Revised: 12/07/2017] [Accepted: 12/08/2017] [Indexed: 12/12/2022]
Abstract
Long interspersed element-1 (LINE-1 or L1) is a transposable element with the ability to self-mobilize throughout the human genome. The L1 elements found in the human brain is hypothesized to date back 56 million years ago and has survived evolution, currently accounting for 17% of the human genome. L1 retrotransposition has been theorized to contribute to somatic mosaicism. This review focuses on the presence of L1 in the healthy and diseased human brain, such as in autism spectrum disorders. Throughout this exploration, we will discuss the impact L1 has on neurological disorders that can occur throughout the human lifetime. With this, we hope to better understand the complex role of L1 in the human brain development and its implications to human cognition. © 2017 Wiley Periodicals, Inc. Develop Neurobiol 78: 434-455, 2018.
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Affiliation(s)
- Nicole A Suarez
- Department of Pediatrics/Rady Children's Hospital San Diego, University of California San Diego, La Jolla, California, 92093
| | - Angela Macia
- Department of Pediatrics/Rady Children's Hospital San Diego, University of California San Diego, La Jolla, California, 92093
| | - Alysson R Muotri
- Department of Pediatrics/Rady Children's Hospital San Diego, University of California San Diego, La Jolla, California, 92093
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20
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Liu N, Lee CH, Swigut T, Grow E, Gu B, Bassik MC, Wysocka J. Selective silencing of euchromatic L1s revealed by genome-wide screens for L1 regulators. Nature 2017; 553:228-232. [PMID: 29211708 PMCID: PMC5774979 DOI: 10.1038/nature25179] [Citation(s) in RCA: 202] [Impact Index Per Article: 28.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Accepted: 11/28/2017] [Indexed: 02/08/2023]
Abstract
Transposable elements, also known as transposons, are now recognized not only as parasitic DNA, the spread of which in the genome must be controlled by the host, but also as major players in genome evolution and regulation. Long interspersed element-1 (LINE-1, also known as L1), the only currently autonomous mobile transposon in humans, occupies 17% of the genome and generates inter- and intra-individual genetic variation, in some cases resulting in disease. However, how L1 activity is controlled and the function of L1s in host gene regulation are not completely understood. Here we use CRISPR-Cas9 screening strategies in two distinct human cell lines to provide a genome-wide survey of genes involved in the control of L1 retrotransposition. We identify functionally diverse genes that either promote or restrict L1 retrotransposition. These genes, which are often associated with human diseases, control the L1 life cycle at the transcriptional or the post-transcriptional level in a manner that can depend on the endogenous L1 nucleotide sequence, underscoring the complexity of L1 regulation. We further investigate the restriction of L1 by the protein MORC2 and by the human silencing hub (HUSH) complex subunits MPP8 and TASOR. HUSH and MORC2 can selectively bind evolutionarily young, full-length L1s located within transcriptionally permissive euchromatic environments, and promote deposition of histone H3 Lys9 trimethylation (H3K9me3) for transcriptional silencing. Notably, these silencing events often occur within introns of transcriptionally active genes, and lead to the downregulation of host gene expression in a HUSH-, MORC2-, and L1-dependent manner. Together, these results provide a rich resource for studies of L1 retrotransposition, elucidate a novel L1 restriction pathway and illustrate how epigenetic silencing of transposable elements rewires host gene expression programs.
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Affiliation(s)
- Nian Liu
- Department of Chemical and Systems Biology, Stanford School of Medicine, Stanford University, Stanford, California 94305, USA
| | - Cameron H Lee
- Department of Genetics, Stanford School of Medicine, Stanford University, Stanford, California 94305, USA
| | - Tomek Swigut
- Department of Chemical and Systems Biology, Stanford School of Medicine, Stanford University, Stanford, California 94305, USA
| | - Edward Grow
- Department of Genetics, Stanford School of Medicine, Stanford University, Stanford, California 94305, USA
| | - Bo Gu
- Department of Chemical and Systems Biology, Stanford School of Medicine, Stanford University, Stanford, California 94305, USA
| | - Michael C Bassik
- Department of Genetics, Stanford School of Medicine, Stanford University, Stanford, California 94305, USA.,Stanford University Chemistry, Engineering, and Medicine for Human Health (ChEM-H), Stanford School of Medicine, Stanford University, Stanford, California 94305, USA
| | - Joanna Wysocka
- Department of Chemical and Systems Biology, Stanford School of Medicine, Stanford University, Stanford, California 94305, USA.,Institute of Stem Cell Biology and Regenerative Medicine, Stanford School of Medicine, Stanford University, Stanford, California 94305, USA.,Department of Developmental Biology, Stanford School of Medicine, Stanford University, Stanford, California 94305, USA.,Howard Hughes Medical Institute, Stanford School of Medicine, Stanford University, Stanford, California 94305, USA
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21
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Treiber CD, Waddell S. Resolving the prevalence of somatic transposition in Drosophila. eLife 2017; 6. [PMID: 28742021 PMCID: PMC5553932 DOI: 10.7554/elife.28297] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Accepted: 07/21/2017] [Indexed: 11/13/2022] Open
Abstract
Somatic transposition in mammals and insects could increase cellular diversity and neural mobilization has been implicated in age-dependent decline. To understand the impact of transposition in somatic cells it is essential to reliably measure the frequency and map locations of new insertions. Here we identified thousands of putative somatic transposon insertions in neurons from individual Drosophila melanogaster using whole-genome sequencing. However, the number of de novo insertions did not correlate with transposon expression or fly age. Analysing our data with exons as 'immobile genetic elements' revealed a similar frequency of unexpected exon translocations. A new sequencing strategy that recovers transposon: chromosome junction information revealed most putative de novo transposon and exon insertions likely result from unavoidable chimeric artefacts. Reanalysis of other published data suggests similar artefacts are often mistaken for genuine somatic transposition. We conclude that somatic transposition is less prevalent in Drosophila than previously envisaged.
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Affiliation(s)
- Christoph D Treiber
- Centre for Neural Circuits and Behaviour, The University of Oxford, Oxford, United Kingdom
| | - Scott Waddell
- Centre for Neural Circuits and Behaviour, The University of Oxford, Oxford, United Kingdom
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Abstract
Transposable elements give rise to interspersed repeats, sequences that comprise most of our genomes. These mobile DNAs have been historically underappreciated - both because they have been presumed to be unimportant, and because their high copy number and variability pose unique technical challenges. Neither impediment now seems steadfast. Interest in the human mobilome has never been greater, and methods enabling its study are maturing at a fast pace. This Review describes the activity of transposable elements in human cancers, particularly long interspersed element-1 (LINE-1). LINE-1 sequences are self-propagating, protein-coding retrotransposons, and their activity results in somatically acquired insertions in cancer genomes. Altered expression of transposable elements and animation of genomic LINE-1 sequences appear to be hallmarks of cancer, and can be responsible for driving mutations in tumorigenesis.
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Affiliation(s)
- Kathleen H Burns
- Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
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23
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Transposable elements in cancer. NATURE REVIEWS. CANCER 2017. [PMID: 28642606 DOI: 10.1038/nrc.2017.35+[doi]] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Transposable elements give rise to interspersed repeats, sequences that comprise most of our genomes. These mobile DNAs have been historically underappreciated - both because they have been presumed to be unimportant, and because their high copy number and variability pose unique technical challenges. Neither impediment now seems steadfast. Interest in the human mobilome has never been greater, and methods enabling its study are maturing at a fast pace. This Review describes the activity of transposable elements in human cancers, particularly long interspersed element-1 (LINE-1). LINE-1 sequences are self-propagating, protein-coding retrotransposons, and their activity results in somatically acquired insertions in cancer genomes. Altered expression of transposable elements and animation of genomic LINE-1 sequences appear to be hallmarks of cancer, and can be responsible for driving mutations in tumorigenesis.
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24
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The Role of Somatic L1 Retrotransposition in Human Cancers. Viruses 2017; 9:v9060131. [PMID: 28561751 PMCID: PMC5490808 DOI: 10.3390/v9060131] [Citation(s) in RCA: 67] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Revised: 05/09/2017] [Accepted: 05/22/2017] [Indexed: 02/06/2023] Open
Abstract
The human LINE-1 (or L1) element is a non-LTR retrotransposon that is mobilized through an RNA intermediate by an L1-encoded reverse transcriptase and other L1-encoded proteins. L1 elements remain actively mobile today and continue to mutagenize human genomes. Importantly, when new insertions disrupt gene function, they can cause diseases. Historically, L1s were thought to be active in the germline but silenced in adult somatic tissues. However, recent studies now show that L1 is active in at least some somatic tissues, including epithelial cancers. In this review, we provide an overview of these recent developments, and examine evidence that somatic L1 retrotransposition can initiate and drive tumorigenesis in humans. Recent studies have: (i) cataloged somatic L1 activity in many epithelial tumor types; (ii) identified specific full-length L1 source elements that give rise to somatic L1 insertions; and (iii) determined that L1 promoter hypomethylation likely plays an early role in the derepression of L1s in somatic tissues. A central challenge moving forward is to determine the extent to which L1 driver mutations can promote tumor initiation, evolution, and metastasis in humans.
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