1
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Pabis K, Barardo D, Sirbu O, Selvarajoo K, Gruber J, Kennedy BK. A concerted increase in readthrough and intron retention drives transposon expression during aging and senescence. eLife 2024; 12:RP87811. [PMID: 38567944 PMCID: PMC10990488 DOI: 10.7554/elife.87811] [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: 04/05/2024] Open
Abstract
Aging and senescence are characterized by pervasive transcriptional dysfunction, including increased expression of transposons and introns. Our aim was to elucidate mechanisms behind this increased expression. Most transposons are found within genes and introns, with a large minority being close to genes. This raises the possibility that transcriptional readthrough and intron retention are responsible for age-related changes in transposon expression rather than expression of autonomous transposons. To test this, we compiled public RNA-seq datasets from aged human fibroblasts, replicative and drug-induced senescence in human cells, and RNA-seq from aging mice and senescent mouse cells. Indeed, our reanalysis revealed a correlation between transposons expression, intron retention, and transcriptional readthrough across samples and within samples. Both intron retention and readthrough increased with aging or cellular senescence and these transcriptional defects were more pronounced in human samples as compared to those of mice. In support of a causal connection between readthrough and transposon expression, analysis of models showing induced transcriptional readthrough confirmed that they also show elevated transposon expression. Taken together, our data suggest that elevated transposon reads during aging seen in various RNA-seq dataset are concomitant with multiple transcriptional defects. Intron retention and transcriptional readthrough are the most likely explanation for the expression of transposable elements that lack a functional promoter.
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Affiliation(s)
- Kamil Pabis
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of SingaporeSingaporeSingapore
- Healthy Longevity Translational Research Programme, Yong Loo Lin School of Medicine, National University of SingaporeSingaporeSingapore
- Centre for Healthy Longevity, National University Health SystemSingaporeSingapore
| | - Diogo Barardo
- Healthy Longevity Translational Research Programme, Yong Loo Lin School of Medicine, National University of SingaporeSingaporeSingapore
- Centre for Healthy Longevity, National University Health SystemSingaporeSingapore
| | - Olga Sirbu
- Bioinformatics Institute, Agency for Science, Technology and Research (A*STAR)SingaporeSingapore
| | - Kumar Selvarajoo
- Bioinformatics Institute, Agency for Science, Technology and Research (A*STAR)SingaporeSingapore
- Singapore Institute of Food and Biotechnology Innovation, Agency for Science, Technology and Research (A*STAR)SingaporeSingapore
- NUS Synthetic Biology for Clinical and Technological Innovation (SynCTI), National University of SingaporeSingaporeSingapore
- School of Biological Sciences, Nanyang Technological UniversitySingaporeSingapore
| | - Jan Gruber
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of SingaporeSingaporeSingapore
- Science Divisions, Yale-NUS CollegeSingaporeSingapore
| | - Brian K Kennedy
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of SingaporeSingaporeSingapore
- Healthy Longevity Translational Research Programme, Yong Loo Lin School of Medicine, National University of SingaporeSingaporeSingapore
- Centre for Healthy Longevity, National University Health SystemSingaporeSingapore
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2
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Lee M, Ahmad SF, Xu J. Regulation and function of transposable elements in cancer genomes. Cell Mol Life Sci 2024; 81:157. [PMID: 38556602 PMCID: PMC10982106 DOI: 10.1007/s00018-024-05195-2] [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: 12/03/2023] [Revised: 02/28/2024] [Accepted: 03/01/2024] [Indexed: 04/02/2024]
Abstract
Over half of human genomic DNA is composed of repetitive sequences generated throughout evolution by prolific mobile genetic parasites called transposable elements (TEs). Long disregarded as "junk" or "selfish" DNA, TEs are increasingly recognized as formative elements in genome evolution, wired intimately into the structure and function of the human genome. Advances in sequencing technologies and computational methods have ushered in an era of unprecedented insight into how TE activity impacts human biology in health and disease. Here we discuss the current views on how TEs have shaped the regulatory landscape of the human genome, how TE activity is implicated in human cancers, and how recent findings motivate novel strategies to leverage TE activity for improved cancer therapy. Given the crucial role of methodological advances in TE biology, we pair our conceptual discussions with an in-depth review of the inherent technical challenges in studying repeats, specifically related to structural variation, expression analyses, and chromatin regulation. Lastly, we provide a catalog of existing and emerging assays and bioinformatic software that altogether are enabling the most sophisticated and comprehensive investigations yet into the regulation and function of interspersed repeats in cancer genomes.
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Affiliation(s)
- Michael Lee
- Department of Pediatrics, Children's Medical Center Research Institute, University of Texas Southwestern Medical Center, 6000 Harry Hines Blvd., Dallas, TX, 75390, USA.
| | - Syed Farhan Ahmad
- Department of Pathology, Center of Excellence for Leukemia Studies, St. Jude Children's Research Hospital, 262 Danny Thomas Place - MS 345, Memphis, TN, 38105, USA
| | - Jian Xu
- Department of Pathology, Center of Excellence for Leukemia Studies, St. Jude Children's Research Hospital, 262 Danny Thomas Place - MS 345, Memphis, TN, 38105, USA.
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3
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Toda T, Bedrosian TA, Schafer ST, Cuoco MS, Linker SB, Ghassemzadeh S, Mitchell L, Whiteley JT, Novaresi N, McDonald AH, Gallina IS, Yoon H, Hester ME, Pena M, Lim C, Suljic E, AlFatah Mansour A, Boulard M, Parylak SL, Gage FH. Long interspersed nuclear elements safeguard neural progenitors from precocious differentiation. Cell Rep 2024; 43:113774. [PMID: 38349791 PMCID: PMC10948021 DOI: 10.1016/j.celrep.2024.113774] [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: 11/12/2022] [Revised: 11/30/2023] [Accepted: 01/24/2024] [Indexed: 02/15/2024] Open
Abstract
Long interspersed nuclear element-1 (L1 or LINE-1) is a highly abundant mobile genetic element in both humans and mice, comprising almost 20% of each genome. L1s are silenced by several mechanisms, as their uncontrolled expression has the potential to induce genomic instability. However, L1s are paradoxically expressed at high levels in differentiating neural progenitor cells. Using in vitro and in vivo techniques to modulate L1 expression, we report that L1s play a critical role in both human and mouse brain development by regulating the rate of neural differentiation in a reverse-transcription-independent manner.
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Affiliation(s)
- Tomohisa Toda
- Laboratory of Genetics, The Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA; Laboratory of Neural Epigenomics, Institute of Medical Physics and Micro-tissue Engineering, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany; Nuclear Architecture in Neural Plasticity and Aging Laboratory, German Center for Neurodegenerative Diseases, 01307 Dresden, Germany.
| | - Tracy A Bedrosian
- Laboratory of Genetics, The Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA; Institute for Genomic Medicine, Nationwide Children's Hospital, Columbus, OH 43205, USA
| | - Simon T Schafer
- Laboratory of Genetics, The Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA; Department of Psychiatry and Psychotherapy, School of Medicine and Health, Technical University of Munich, Munich, Germany; TUM Center for Organoid Systems (COS), Munich Institute of Biomedical Engineering, Garching, Germany
| | - Michael S Cuoco
- Laboratory of Genetics, The Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA; Computational Neural DNA Dynamics Lab, Department of Cognitive Science, University of California, San Diego, San Diego, CA, USA; Bioinformatics and Systems Biology Graduate Program, University of California, San Diego, San Diego, CA, USA
| | - Sara B Linker
- Laboratory of Genetics, The Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Saeed Ghassemzadeh
- Laboratory of Genetics, The Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Lisa Mitchell
- Laboratory of Genetics, The Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Jack T Whiteley
- Laboratory of Genetics, The Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Nicole Novaresi
- Laboratory of Genetics, The Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Aidan H McDonald
- Laboratory of Genetics, The Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Iryna S Gallina
- Laboratory of Genetics, The Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Hyojung Yoon
- Institute for Genomic Medicine, Nationwide Children's Hospital, Columbus, OH 43205, USA
| | - Mark E Hester
- Institute for Genomic Medicine, Nationwide Children's Hospital, Columbus, OH 43205, USA
| | - Monique Pena
- Laboratory of Genetics, The Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA; Department of Psychiatry and Psychotherapy, School of Medicine and Health, Technical University of Munich, Munich, Germany; TUM Center for Organoid Systems (COS), Munich Institute of Biomedical Engineering, Garching, Germany
| | - Christina Lim
- Laboratory of Genetics, The Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Emelia Suljic
- Laboratory of Genetics, The Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Abed AlFatah Mansour
- Laboratory of Genetics, The Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Matthieu Boulard
- Epigenetics & Neurobiology Unit, EMBL Rome, European Molecular Biology Laboratory, Via Ramarini 32, 00015 Monterotondo, Italy
| | - Sarah L Parylak
- Laboratory of Genetics, The Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Fred H Gage
- Laboratory of Genetics, The Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA.
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4
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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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5
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Ilık İA, Glažar P, Tse K, Brändl B, Meierhofer D, Müller FJ, Smith ZD, Aktaş T. Autonomous transposons tune their sequences to ensure somatic suppression. Nature 2024; 626:1116-1124. [PMID: 38355802 PMCID: PMC10901741 DOI: 10.1038/s41586-024-07081-0] [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: 01/24/2023] [Accepted: 01/16/2024] [Indexed: 02/16/2024]
Abstract
Transposable elements (TEs) are a major constituent of human genes, occupying approximately half of the intronic space. During pre-messenger RNA synthesis, intronic TEs are transcribed along with their host genes but rarely contribute to the final mRNA product because they are spliced out together with the intron and rapidly degraded. Paradoxically, TEs are an abundant source of RNA-processing signals through which they can create new introns1, and also functional2 or non-functional chimeric transcripts3. The rarity of these events implies the existence of a resilient splicing code that is able to suppress TE exonization without compromising host pre-mRNA processing. Here we show that SAFB proteins protect genome integrity by preventing retrotransposition of L1 elements while maintaining splicing integrity, via prevention of the exonization of previously integrated TEs. This unique dual role is possible because of L1's conserved adenosine-rich coding sequences that are bound by SAFB proteins. The suppressive activity of SAFB extends to tissue-specific, giant protein-coding cassette exons, nested genes and Tigger DNA transposons. Moreover, SAFB also suppresses LTR/ERV elements in species in which they are still active, such as mice and flies. A significant subset of splicing events suppressed by SAFB in somatic cells are activated in the testis, coinciding with low SAFB expression in postmeiotic spermatids. Reminiscent of the division of labour between innate and adaptive immune systems that fight external pathogens, our results uncover SAFB proteins as an RNA-based, pattern-guided, non-adaptive defence system against TEs in the soma, complementing the RNA-based, adaptive Piwi-interacting RNA pathway of the germline.
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Affiliation(s)
- İbrahim Avşar Ilık
- Otto Warburg Laboratories, Max Planck Institute for Molecular Genetics, Berlin, Germany
| | - Petar Glažar
- Otto Warburg Laboratories, Max Planck Institute for Molecular Genetics, Berlin, Germany
| | - Kevin Tse
- Department of Genetics, Yale Stem Cell Center, Yale School of Medicine, New Haven, CT, USA
| | - Björn Brändl
- Universitätsklinikum Schleswig-Holstein Campus Kiel, Zentrum für Integrative Psychiatrie, Kiel, Germany
- Department of Genome Regulation, Max Planck Institute for Molecular Genetics, Berlin, Germany
| | - David Meierhofer
- Mass Spectrometry Joint Facilities Scientific Service, Max Planck Institute for Molecular Genetics, Berlin, Germany
| | - Franz-Josef Müller
- Universitätsklinikum Schleswig-Holstein Campus Kiel, Zentrum für Integrative Psychiatrie, Kiel, Germany
- Department of Genome Regulation, Max Planck Institute for Molecular Genetics, Berlin, Germany
| | - Zachary D Smith
- Department of Genetics, Yale Stem Cell Center, Yale School of Medicine, New Haven, CT, USA
| | - Tuğçe Aktaş
- Otto Warburg Laboratories, Max Planck Institute for Molecular Genetics, Berlin, Germany.
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6
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Liang Y, Qu X, Shah NM, Wang T. Towards targeting transposable elements for cancer therapy. Nat Rev Cancer 2024; 24:123-140. [PMID: 38228901 DOI: 10.1038/s41568-023-00653-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 12/04/2023] [Indexed: 01/18/2024]
Abstract
Transposable elements (TEs) represent almost half of the human genome. Historically deemed 'junk DNA', recent technological advancements have stimulated a wave of research into the functional impact of TEs on gene-regulatory networks in evolution and development, as well as in diseases including cancer. The genetic and epigenetic evolution of cancer involves the exploitation of TEs, whereby TEs contribute directly to cancer-specific gene activities. This Review provides a perspective on the role of TEs in cancer as being a 'double-edged sword', both promoting cancer evolution and representing a vulnerability that could be exploited in cancer therapy. We discuss how TEs affect transcriptome regulation and other cellular processes in cancer. We highlight the potential of TEs as therapeutic targets for cancer. We also summarize technical hurdles in the characterization of TEs with genomic assays. Last, we outline open questions and exciting future research avenues.
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Affiliation(s)
- Yonghao Liang
- Department of Genetics, Washington University School of Medicine, Saint Louis, MO, USA
- Center for Genome Sciences and Systems Biology, Washington University School of Medicine, Saint Louis, MO, USA
| | - Xuan Qu
- Department of Genetics, Washington University School of Medicine, Saint Louis, MO, USA
- Center for Genome Sciences and Systems Biology, Washington University School of Medicine, Saint Louis, MO, USA
| | - Nakul M Shah
- Division of Cancer Medicine, University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Ting Wang
- Department of Genetics, Washington University School of Medicine, Saint Louis, MO, USA.
- Center for Genome Sciences and Systems Biology, Washington University School of Medicine, Saint Louis, MO, USA.
- McDonnell Genome Institute, Washington University School of Medicine, Saint Louis, MO, USA.
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7
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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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8
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Li X, Lu K, Chen X, Tu K, Xie D. capTEs enables locus-specific dissection of transcriptional outputs from reference and nonreference transposable elements. Commun Biol 2023; 6:974. [PMID: 37741908 PMCID: PMC10517987 DOI: 10.1038/s42003-023-05349-1] [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: 12/23/2022] [Accepted: 09/12/2023] [Indexed: 09/25/2023] Open
Abstract
Transposable elements (TEs) serve as both insertional mutagens and regulatory elements in cells, and their aberrant activity is increasingly being revealed to contribute to diseases and cancers. However, measuring the transcriptional consequences of nonreference and young TEs at individual loci remains challenging with current methods, primarily due to technical limitations, including short read lengths generated and insufficient coverage in target regions. Here, we introduce a long-read targeted RNA sequencing method, Cas9-assisted profiling TE expression sequencing (capTEs), for quantitative analysis of transcriptional outputs for individual TEs, including transcribed nonreference insertions, noncanonical transcripts from various transcription patterns and their correlations with expression changes in related genes. This method selectively identified TE-containing transcripts and outputted data with up to 90% TE reads, maintaining a comparable data yield to whole-transcriptome sequencing. We applied capTEs to human cancer cells and found that internal and inserted Alu elements may employ distinct regulatory mechanisms to upregulate gene expression. We expect that capTEs will be a critical tool for advancing our understanding of the biological functions of individual TEs at the locus level, revealing their roles as both mutagens and regulators in biological and pathogenic processes.
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Affiliation(s)
- Xuemei Li
- Laboratory of Omics Technology and Bioinformatics, Frontiers Science Center for Disease-related Molecular Network, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan, 610041, China
| | - Keying Lu
- Laboratory of Omics Technology and Bioinformatics, Frontiers Science Center for Disease-related Molecular Network, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan, 610041, China
| | - Xiao Chen
- Laboratory of Omics Technology and Bioinformatics, Frontiers Science Center for Disease-related Molecular Network, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan, 610041, China
| | - Kailing Tu
- Laboratory of Omics Technology and Bioinformatics, Frontiers Science Center for Disease-related Molecular Network, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan, 610041, China
| | - Dan Xie
- Laboratory of Omics Technology and Bioinformatics, Frontiers Science Center for Disease-related Molecular Network, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan, 610041, China.
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9
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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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10
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McKerrow W. Quantification of LINE-1 RNA Expression from Bulk RNA-seq Using L1EM. Methods Mol Biol 2023; 2607:115-126. [PMID: 36449161 DOI: 10.1007/978-1-0716-2883-6_7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
LINE-1 retrotransposons have the potential to cause DNA damage, contribute to genome instability, and induce an interferon response. Thus, accurate measurements of their expression, especially in disease contexts where genome instability and the interferon response are relevant, are of particular importance. Illumina-based bulk RNA sequencing remains the most abundant datatype for measuring gene expression. However, "active" expression from its own internal promoter is only one source of LINE-1 aligning reads in an RNA-seq experiment. With about half a million LINE-1 sequences scattered throughout the genome, many are incorporated into other transcripts that have nothing to do with LINE-1 activity. We call this "passive" co-transcription. Here we will describe how to use L1EM, a computational method that separates active from passive LINE-1 expression at the locus-specific level.
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Affiliation(s)
- Wilson McKerrow
- Institute for Systems Genetics, NYU Langone Health, New York, NY, USA.
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11
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Di Stefano LH, Saba LJ, Oghbaie M, Jiang H, McKerrow W, Benitez-Guijarro M, Taylor MS, LaCava J. Affinity-Based Interactome Analysis of Endogenous LINE-1 Macromolecules. Methods Mol Biol 2023; 2607:215-256. [PMID: 36449166 DOI: 10.1007/978-1-0716-2883-6_12] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
During their proliferation and the host's concomitant attempts to suppress it, LINE-1 (L1) retrotransposons give rise to a collection of heterogeneous ribonucleoproteins (RNPs); their protein and RNA compositions remain poorly defined. The constituents of L1-associated macromolecules can differ depending on numerous factors, including, for example, position within the L1 life cycle, whether the macromolecule is productive or under suppression, and the cell type within which the proliferation is occurring. This chapter describes techniques that aid the capture and characterization of protein and RNA components of L1 macromolecules from tissues that natively express them. The protocols described have been applied to embryonal carcinoma cell lines that are popular model systems for L1 molecular biology (e.g., N2102Ep, NTERA-2, and PA-1 cells), as well as colorectal cancer tissues. N2102Ep cells are given as the use case for this chapter; the protocols should be applicable to essentially any tissue exhibiting endogenous L1 expression with minor modifications.
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12
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Epigenomic landscape study reveals molecular subtypes and EBV-associated regulatory epigenome reprogramming in nasopharyngeal carcinoma. EBioMedicine 2022; 86:104357. [DOI: 10.1016/j.ebiom.2022.104357] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Revised: 10/21/2022] [Accepted: 10/24/2022] [Indexed: 11/13/2022] Open
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13
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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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14
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Taylor D, Lowe R, Philippe C, Cheng KCL, Grant OA, Zabet NR, Cristofari G, Branco MR. Locus-specific chromatin profiling of evolutionarily young transposable elements. Nucleic Acids Res 2022; 50:e33. [PMID: 34908129 PMCID: PMC8989514 DOI: 10.1093/nar/gkab1232] [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: 09/06/2021] [Revised: 11/15/2021] [Accepted: 12/02/2021] [Indexed: 01/13/2023] Open
Abstract
Despite a vast expansion in the availability of epigenomic data, our knowledge of the chromatin landscape at interspersed repeats remains highly limited by difficulties in mapping short-read sequencing data to these regions. In particular, little is known about the locus-specific regulation of evolutionarily young transposable elements (TEs), which have been implicated in genome stability, gene regulation and innate immunity in a variety of developmental and disease contexts. Here we propose an approach for generating locus-specific protein-DNA binding profiles at interspersed repeats, which leverages information on the spatial proximity between repetitive and non-repetitive genomic regions. We demonstrate that the combination of HiChIP and a newly developed mapping tool (PAtChER) yields accurate protein enrichment profiles at individual repetitive loci. Using this approach, we reveal previously unappreciated variation in the epigenetic profiles of young TE loci in mouse and human cells. Insights gained using our method will be invaluable for dissecting the molecular determinants of TE regulation and their impact on the genome.
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Affiliation(s)
- Darren Taylor
- Blizard Institute, Barts and The London School of Medicine and Dentistry, QMUL, London E1 2AT, UK
| | - Robert Lowe
- Blizard Institute, Barts and The London School of Medicine and Dentistry, QMUL, London E1 2AT, UK
| | | | - Kevin C L Cheng
- Blizard Institute, Barts and The London School of Medicine and Dentistry, QMUL, London E1 2AT, UK
| | - Olivia A Grant
- Blizard Institute, Barts and The London School of Medicine and Dentistry, QMUL, London E1 2AT, UK
- School of Life Sciences, University of Essex, Colchester, CO4 3SQ, UK
| | - Nicolae Radu Zabet
- Blizard Institute, Barts and The London School of Medicine and Dentistry, QMUL, London E1 2AT, UK
| | | | - Miguel R Branco
- Blizard Institute, Barts and The London School of Medicine and Dentistry, QMUL, London E1 2AT, UK
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15
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Pfaff AL, Bubb VJ, Quinn JP, Koks S. Locus specific reduction of L1 expression in the cortices of individuals with amyotrophic lateral sclerosis. Mol Brain 2022; 15:25. [PMID: 35346298 PMCID: PMC8961898 DOI: 10.1186/s13041-022-00914-x] [Citation(s) in RCA: 2] [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: 12/13/2021] [Accepted: 03/21/2022] [Indexed: 11/16/2022] Open
Abstract
The activation and dysregulation of retrotransposons has been identified in the CNS of individuals with the fatal neurodegenerative disorder Amyotrophic lateral sclerosis (ALS). This includes elements from multiple different families and subfamilies of retrotransposons, however there is limited knowledge of the specific loci from which this expression occurs in ALS. The long interspersed element-1 (L1) is the only autonomous retrotransposon in the human genome and members of this family of elements maintain the ability to mobilise. Despite L1s contributing to 17% of the human genome only 80-100 L1s encode the required proteins for mobilisation and are retrotransposition competent. Identifying the specific loci from which L1 expression occurs will inform on the potential functional consequences of their expression, such as the potential for somatic retrotransposition or DNA damage caused by the endonuclease activity of the ORF2 protein of the L1. Here we characterised L1 loci expression using the L1EM tool ( https://github.com/FenyoLab/L1EM ) in RNA sequencing data from 518 samples across four tissues (motor cortex, frontal cortex, cerebellum and cervical spinal cord) in the Target ALS cohort obtained from the New York Genome Center. There was a significant reduction in total intact L1 expression (those that encode functional proteins) in two brain regions of individuals with ALS compared to controls and clustering of the ALS brain regions occurred based on their intact L1 expression profile. Although overall the levels of L1 expression were reduced in ALS/ALS with other neurological disorder (ND) there were individuals in which L1s were expressed at much higher levels than the rest of the ALS/ALSND cohort. Expressed L1 loci were more frequently located in introns compared to those not expressed and the level of L1 expression positively correlated with the expression of the gene in which it was located. Significant differences were observed in the expression profiles of L1s in ALS and specific features of these elements, such as location in the genome and whether or not they are intact, were significantly associated with those that were expressed in the cohort.
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Affiliation(s)
- Abigail L. Pfaff
- Perron Institute for Neurological and Translational Science, Perth, 8 Verdun Street, Nedlands, WA 6009 Australia
- Centre for Molecular Medicine and Innovative Therapeutics, Murdoch University, Perth, WA Australia
| | - Vivien J. Bubb
- Department of Pharmacology and Therapeutics, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, UK
| | - John P. Quinn
- Department of Pharmacology and Therapeutics, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, UK
| | - Sulev Koks
- Perron Institute for Neurological and Translational Science, Perth, 8 Verdun Street, Nedlands, WA 6009 Australia
- Centre for Molecular Medicine and Innovative Therapeutics, Murdoch University, Perth, WA Australia
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16
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McKerrow W, Wang X, Mendez-Dorantes C, Mita P, Cao S, Grivainis M, Ding L, LaCava J, Burns KH, Boeke JD, Fenyö D. LINE-1 expression in cancer correlates with p53 mutation, copy number alteration, and S phase checkpoint. Proc Natl Acad Sci U S A 2022; 119:e2115999119. [PMID: 35169076 PMCID: PMC8872788 DOI: 10.1073/pnas.2115999119] [Citation(s) in RCA: 37] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Accepted: 01/14/2022] [Indexed: 12/12/2022] Open
Abstract
Retrotransposons are genomic DNA sequences that copy themselves to new genomic locations via RNA intermediates; LINE-1 is the only active and autonomous retrotransposon in the human genome. The mobility of LINE-1 is largely repressed in somatic tissues but is derepressed in many cancers, where LINE-1 retrotransposition is correlated with p53 mutation and copy number alteration (CNA). In cell lines, inducing LINE-1 expression can cause double-strand breaks (DSBs) and replication stress. Reanalyzing multiomic data from breast, ovarian, endometrial, and colon cancers, we confirmed correlations between LINE-1 expression, p53 mutation status, and CNA. We observed a consistent correlation between LINE-1 expression and the abundance of DNA replication complex components, indicating that LINE-1 may also induce replication stress in human tumors. In endometrial cancer, high-quality phosphoproteomic data allowed us to identify the DSB-induced ATM-MRN-SMC S phase checkpoint pathway as the primary DNA damage response (DDR) pathway associated with LINE-1 expression. Induction of LINE-1 expression in an in vitro model led to increased phosphorylation of MRN complex member RAD50, suggesting that LINE-1 directly activates this pathway.
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Affiliation(s)
- Wilson McKerrow
- Institute for Systems Genetics, New York University Grossman School of Medicine, New York, NY 10016
- Department of Biochemistry and Molecular Pharmacology, New York University Grossman School of Medicine, New York, NY 10016
| | - Xuya Wang
- Institute for Systems Genetics, New York University Grossman School of Medicine, New York, NY 10016
- Department of Biochemistry and Molecular Pharmacology, New York University Grossman School of Medicine, New York, NY 10016
| | - Carlos Mendez-Dorantes
- Department of Oncologic Pathology, Dana-Farber Cancer Institute, Boston, MA 02215
- Department of Pathology, Harvard Medical School, Boston, MA 02115
| | - Paolo Mita
- Institute for Systems Genetics, New York University Grossman School of Medicine, New York, NY 10016
- Department of Biochemistry and Molecular Pharmacology, New York University Grossman School of Medicine, New York, NY 10016
| | - Song Cao
- Department of Medicine and Genetics, Siteman Cancer Center, Washington University in St. Louis, St. Louis, MO 63110
- McDonnell Genome Institute, Washington University in St. Louis, St. Louis, MO 63108
| | - Mark Grivainis
- Institute for Systems Genetics, New York University Grossman School of Medicine, New York, NY 10016
- Department of Biochemistry and Molecular Pharmacology, New York University Grossman School of Medicine, New York, NY 10016
| | - Li Ding
- Department of Medicine and Genetics, Siteman Cancer Center, Washington University in St. Louis, St. Louis, MO 63110
- McDonnell Genome Institute, Washington University in St. Louis, St. Louis, MO 63108
| | - John LaCava
- Laboratory of Cellular and Structural Biology, The Rockefeller University, New York, NY 10065
- European Research Institute for the Biology of Ageing, University Medical Center Groningen, 9713 GZ Groningen, The Netherlands
| | - Kathleen H Burns
- Department of Oncologic Pathology, Dana-Farber Cancer Institute, Boston, MA 02215
- Department of Pathology, Harvard Medical School, Boston, MA 02115
| | - Jef D Boeke
- Institute for Systems Genetics, New York University Grossman School of Medicine, New York, NY 10016;
- Department of Biochemistry and Molecular Pharmacology, New York University Grossman School of Medicine, New York, NY 10016
- Department of Biomedical Engineering, Tandon School of Engineering, Brooklyn, NY11201
| | - David Fenyö
- Institute for Systems Genetics, New York University Grossman School of Medicine, New York, NY 10016;
- Department of Biochemistry and Molecular Pharmacology, New York University Grossman School of Medicine, New York, NY 10016
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17
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The Dynamism of Transposon Methylation for Plant Development and Stress Adaptation. Int J Mol Sci 2021; 22:ijms222111387. [PMID: 34768817 PMCID: PMC8583499 DOI: 10.3390/ijms222111387] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 10/13/2021] [Accepted: 10/19/2021] [Indexed: 02/06/2023] Open
Abstract
Plant development processes are regulated by epigenetic alterations that shape nuclear structure, gene expression, and phenotypic plasticity; these alterations can provide the plant with protection from environmental stresses. During plant growth and development, these processes play a significant role in regulating gene expression to remodel chromatin structure. These epigenetic alterations are mainly regulated by transposable elements (TEs) whose abundance in plant genomes results in their interaction with genomes. Thus, TEs are the main source of epigenetic changes and form a substantial part of the plant genome. Furthermore, TEs can be activated under stress conditions, and activated elements cause mutagenic effects and substantial genetic variability. This introduces novel gene functions and structural variation in the insertion sites and primarily contributes to epigenetic modifications. Altogether, these modifications indirectly or directly provide the ability to withstand environmental stresses. In recent years, many studies have shown that TE methylation plays a major role in the evolution of the plant genome through epigenetic process that regulate gene imprinting, thereby upholding genome stability. The induced genetic rearrangements and insertions of mobile genetic elements in regions of active euchromatin contribute to genome alteration, leading to genomic stress. These TE-mediated epigenetic modifications lead to phenotypic diversity, genetic variation, and environmental stress tolerance. Thus, TE methylation is essential for plant evolution and stress adaptation, and TEs hold a relevant military position in the plant genome. High-throughput techniques have greatly advanced the understanding of TE-mediated gene expression and its associations with genome methylation and suggest that controlled mobilization of TEs could be used for crop breeding. However, development application in this area has been limited, and an integrated view of TE function and subsequent processes is lacking. In this review, we explore the enormous diversity and likely functions of the TE repertoire in adaptive evolution and discuss some recent examples of how TEs impact gene expression in plant development and stress adaptation.
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18
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Thind AS, Monga I, Thakur PK, Kumari P, Dindhoria K, Krzak M, Ranson M, Ashford B. Demystifying emerging bulk RNA-Seq applications: the application and utility of bioinformatic methodology. Brief Bioinform 2021; 22:6330938. [PMID: 34329375 DOI: 10.1093/bib/bbab259] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2021] [Revised: 06/14/2021] [Accepted: 06/18/2021] [Indexed: 12/13/2022] Open
Abstract
Significant innovations in next-generation sequencing techniques and bioinformatics tools have impacted our appreciation and understanding of RNA. Practical RNA sequencing (RNA-Seq) applications have evolved in conjunction with sequence technology and bioinformatic tools advances. In most projects, bulk RNA-Seq data is used to measure gene expression patterns, isoform expression, alternative splicing and single-nucleotide polymorphisms. However, RNA-Seq holds far more hidden biological information including details of copy number alteration, microbial contamination, transposable elements, cell type (deconvolution) and the presence of neoantigens. Recent novel and advanced bioinformatic algorithms developed the capacity to retrieve this information from bulk RNA-Seq data, thus broadening its scope. The focus of this review is to comprehend the emerging bulk RNA-Seq-based analyses, emphasizing less familiar and underused applications. In doing so, we highlight the power of bulk RNA-Seq in providing biological insights.
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Affiliation(s)
- Amarinder Singh Thind
- University of Wollongong, Wollongong, Australia.,Illawarra Health and Medical Research Institute, Wollongong, Australia
| | - Isha Monga
- Columbia University, New York City, NY, USA
| | | | - Pallawi Kumari
- Institute of Microbial Technology, Council of Scientific and Industrial Research, Chandigarh, India
| | - Kiran Dindhoria
- Institute of Microbial Technology, Council of Scientific and Industrial Research, Chandigarh, India
| | | | - Marie Ranson
- University of Wollongong, Wollongong, Australia.,Illawarra Health and Medical Research Institute, Wollongong, Australia
| | - Bruce Ashford
- University of Wollongong, Wollongong, Australia.,Illawarra Health and Medical Research Institute, Wollongong, Australia
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19
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Stow EC, Kaul T, deHaro DL, Dem MR, Beletsky AG, Morales ME, Du Q, LaRosa AJ, Yang H, Smither E, Baddoo M, Ungerleider N, Deininger P, Belancio VP. Organ-, sex- and age-dependent patterns of endogenous L1 mRNA expression at a single locus resolution. Nucleic Acids Res 2021; 49:5813-5831. [PMID: 34023901 PMCID: PMC8191783 DOI: 10.1093/nar/gkab369] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 04/21/2021] [Accepted: 04/28/2021] [Indexed: 11/13/2022] Open
Abstract
Expression of L1 mRNA, the first step in the L1 copy-and-paste amplification cycle, is a prerequisite for L1-associated genomic instability. We used a reported stringent bioinformatics method to parse L1 mRNA transcripts and measure the level of L1 mRNA expressed in mouse and rat organs at a locus-specific resolution. This analysis determined that mRNA expression of L1 loci in rodents exhibits striking organ specificity with less than 0.8% of loci shared between organs of the same organism. This organ specificity in L1 mRNA expression is preserved in male and female mice and across age groups. We discovered notable differences in L1 mRNA expression between sexes with only 5% of expressed L1 loci shared between male and female mice. Moreover, we report that the levels of total L1 mRNA expression and the number and spectrum of expressed L1 loci fluctuate with age as independent variables, demonstrating different patterns in different organs and sexes. Overall, our comparisons between organs and sexes and across ages ranging from 2 to 22 months establish previously unforeseen dynamic changes in L1 mRNA expression in vivo. These findings establish the beginning of an atlas of endogenous L1 mRNA expression across a broad range of biological variables that will guide future studies.
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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, LA 70112 USA
| | - Tiffany Kaul
- 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
| | - Dawn L deHaro
- 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, LA 70112 USA
| | - Madeleine R Dem
- 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, LA 70112 USA
| | - Anna G Beletsky
- 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, LA 70112 USA
| | - Maria E Morales
- 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
| | - Qianhui Du
- 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, LA 70112 USA
| | - Alexis J LaRosa
- Department of Structural and Cellular Biology, Tulane School of Medicine, 1430 Tulane Ave, New Orleans, LA 70112 USA
| | - Hanlin Yang
- Tulane Cancer Center, Tulane Health Sciences Center, 1700 Tulane Ave, New Orleans, LA 70112, USA
| | - Emily Smither
- Department of Structural and Cellular Biology, Tulane School of Medicine, 1430 Tulane Ave, New Orleans, LA 70112 USA
| | - Melody Baddoo
- Tulane Cancer Center, Tulane Health Sciences Center, 1700 Tulane Ave, New Orleans, LA 70112, USA
| | - Nathan Ungerleider
- 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
- 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, LA 70112 USA
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20
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Briggs EM, McKerrow W, Mita P, Boeke JD, Logan SK, Fenyö D. RIP-seq reveals LINE-1 ORF1p association with p-body enriched mRNAs. Mob DNA 2021; 12:5. [PMID: 33563338 PMCID: PMC7874467 DOI: 10.1186/s13100-021-00233-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Accepted: 01/27/2021] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Long INterspersed Element-1 (LINE-1) is an autonomous retroelement able to "copy-and-paste" itself into new loci of the host genome through a process called retrotransposition. The LINE-1 bicistronic mRNA codes for two proteins, ORF1p, a nucleic acid chaperone, and ORF2p, a protein with endonuclease and reverse transcriptase activity. Both proteins bind LINE-1 mRNA in cis and are necessary for retrotransposition. While LINE-1 transcription is usually repressed in most healthy somatic cells through a plethora of mechanisms, ORF1p expression has been observed in nearly 50% of tumors, and new LINE-1 insertions have been documented in a similar fraction of tumors, including prostate cancer. RESULTS Here, we utilized RNA ImmunoPrecipitation (RIP) and the L1EM analysis software to identify ORF1p bound RNA in prostate cancer cells. We identified LINE-1 loci that were expressed in parental androgen sensitive and androgen independent clonal derivatives. In all androgen independent cells, we found higher levels of LINE-1 RNA, as well as unique expression patterns of LINE-1 loci. Interestingly, we observed that ORF1p bound many non-LINE-1 mRNA in all prostate cancer cell lines evaluated, and polyA RNA, and RNA localized in p-bodies were especially enriched. Furthermore, the expression levels of RNAs identified in our ORF1p RIP correlated with RNAs expressed in LINE-1 positive tumors from The Cancer Genome Atlas (TCGA). CONCLUSION Our results show a significant remodeling of LINE-1 loci expression in androgen independent cell lines when compared to parental androgen dependent cells. Additionally, we found that ORF1p bound a significant amount of non-LINE-1 mRNA, and that the enriched ORF1p bound mRNAs are also amplified in LINE-1 expressing TCGA prostate tumors, indicating the biological relevance of our findings to prostate cancer.
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Affiliation(s)
- Erica M Briggs
- Departments of Biochemistry and Molecular Pharmacology, New York University, 450 East 29th Street, Room 321, New York, NY, 10016, USA
| | - Wilson McKerrow
- Departments of Biochemistry and Molecular Pharmacology, New York University, 450 East 29th Street, Room 321, New York, NY, 10016, USA
- Institute for Systems Genetics, New York University Grossman School of Medicine, 435 East 30th St, 9th Floor, NY, 10016, New York, USA
| | - Paolo Mita
- Departments of Biochemistry and Molecular Pharmacology, New York University, 450 East 29th Street, Room 321, New York, NY, 10016, USA
- Institute for Systems Genetics, New York University Grossman School of Medicine, 435 East 30th St, 9th Floor, NY, 10016, New York, USA
| | - Jef D Boeke
- Departments of Biochemistry and Molecular Pharmacology, New York University, 450 East 29th Street, Room 321, New York, NY, 10016, USA
- Institute for Systems Genetics, New York University Grossman School of Medicine, 435 East 30th St, 9th Floor, NY, 10016, New York, USA
| | - Susan K Logan
- Departments of Biochemistry and Molecular Pharmacology, New York University, 450 East 29th Street, Room 321, New York, NY, 10016, USA.
- Urology, New York University Grossman School of Medicine, 450 East 29th Street, Room 321, New York, NY, 10016, USA.
| | - David Fenyö
- Departments of Biochemistry and Molecular Pharmacology, New York University, 450 East 29th Street, Room 321, New York, NY, 10016, USA.
- Institute for Systems Genetics, New York University Grossman School of Medicine, 435 East 30th St, 9th Floor, NY, 10016, New York, USA.
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21
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Shao W, Wang T. Transcript assembly improves expression quantification of transposable elements in single-cell RNA-seq data. Genome Res 2021; 31:88-100. [PMID: 33355230 PMCID: PMC7849386 DOI: 10.1101/gr.265173.120] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Accepted: 11/24/2020] [Indexed: 12/28/2022]
Abstract
Transposable elements (TEs) are an integral part of the host transcriptome. TE-containing noncoding RNAs (ncRNAs) show considerable tissue specificity and play important roles during development, including stem cell maintenance and cell differentiation. Recent advances in single-cell RNA-seq (scRNA-seq) revolutionized cell type-specific gene expression analysis. However, effective scRNA-seq quantification tools tailored for TEs are lacking, limiting our ability to dissect TE expression dynamics at single-cell resolution. To address this issue, we established a TE expression quantification pipeline that is compatible with scRNA-seq data generated across multiple technology platforms. We constructed TE-containing ncRNA references using bulk RNA-seq data and showed that quantifying TE expression at the transcript level effectively reduces noise. As proof of principle, we applied this strategy to mouse embryonic stem cells and successfully captured the expression profile of endogenous retroviruses in single cells. We further expanded our analysis to scRNA-seq data from early stages of mouse embryogenesis. Our results illustrated the dynamic TE expression at preimplantation stages and revealed 146 TE-containing ncRNA transcripts with substantial tissue specificity during gastrulation and early organogenesis.
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Affiliation(s)
- Wanqing Shao
- Department of Genetics, Washington University School of Medicine, St. Louis, Missouri 63110, USA
- Edison Family Center for Genome Sciences and Systems Biology, Washington University School of Medicine, St. Louis, Missouri 63110, USA
| | - Ting Wang
- Department of Genetics, Washington University School of Medicine, St. Louis, Missouri 63110, USA
- Edison Family Center for Genome Sciences and Systems Biology, Washington University School of Medicine, St. Louis, Missouri 63110, USA
- McDonnell Genome Institute, Washington University School of Medicine, St. Louis, Missouri 63108, USA
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22
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Marasca F, Gasparotto E, Polimeni B, Vadalà R, Ranzani V, Bodega B. The Sophisticated Transcriptional Response Governed by Transposable Elements in Human Health and Disease. Int J Mol Sci 2020; 21:ijms21093201. [PMID: 32366056 PMCID: PMC7247572 DOI: 10.3390/ijms21093201] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Revised: 04/29/2020] [Accepted: 04/29/2020] [Indexed: 01/15/2023] Open
Abstract
Transposable elements (TEs), which cover ~45% of the human genome, although firstly considered as “selfish” DNA, are nowadays recognized as driving forces in eukaryotic genome evolution. This capability resides in generating a plethora of sophisticated RNA regulatory networks that influence the cell type specific transcriptome in health and disease. Indeed, TEs are transcribed and their RNAs mediate multi-layered transcriptional regulatory functions in cellular identity establishment, but also in the regulation of cellular plasticity and adaptability to environmental cues, as occurs in the immune response. Moreover, TEs transcriptional deregulation also evolved to promote pathogenesis, as in autoimmune and inflammatory diseases and cancers. Importantly, many of these findings have been achieved through the employment of Next Generation Sequencing (NGS) technologies and bioinformatic tools that are in continuous improvement to overcome the limitations of analyzing TEs sequences. However, they are highly homologous, and their annotation is still ambiguous. Here, we will review some of the most recent findings, questions and improvements to study at high resolution this intriguing portion of the human genome in health and diseases, opening the scenario to novel therapeutic opportunities.
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Affiliation(s)
- Federica Marasca
- Fondazione INGM, Istituto Nazionale di Genetica Molecolare “Enrica e Romeo Invernizzi”, 20122 Milan, Italy; (F.M.); (E.G.); (B.P.); (R.V.); (V.R.)
| | - Erica Gasparotto
- Fondazione INGM, Istituto Nazionale di Genetica Molecolare “Enrica e Romeo Invernizzi”, 20122 Milan, Italy; (F.M.); (E.G.); (B.P.); (R.V.); (V.R.)
| | - Benedetto Polimeni
- Fondazione INGM, Istituto Nazionale di Genetica Molecolare “Enrica e Romeo Invernizzi”, 20122 Milan, Italy; (F.M.); (E.G.); (B.P.); (R.V.); (V.R.)
| | - Rebecca Vadalà
- Fondazione INGM, Istituto Nazionale di Genetica Molecolare “Enrica e Romeo Invernizzi”, 20122 Milan, Italy; (F.M.); (E.G.); (B.P.); (R.V.); (V.R.)
- Translational and Molecular Medicine, DIMET, University of Milan-Bicocca, 20900 Monza, Italy
| | - Valeria Ranzani
- Fondazione INGM, Istituto Nazionale di Genetica Molecolare “Enrica e Romeo Invernizzi”, 20122 Milan, Italy; (F.M.); (E.G.); (B.P.); (R.V.); (V.R.)
| | - Beatrice Bodega
- Fondazione INGM, Istituto Nazionale di Genetica Molecolare “Enrica e Romeo Invernizzi”, 20122 Milan, Italy; (F.M.); (E.G.); (B.P.); (R.V.); (V.R.)
- Correspondence:
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23
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Kaul T, Morales ME, Sartor AO, Belancio VP, Deininger P. Comparative analysis on the expression of L1 loci using various RNA-Seq preparations. Mob DNA 2020; 11:2. [PMID: 31921361 PMCID: PMC6945437 DOI: 10.1186/s13100-019-0194-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Accepted: 12/05/2019] [Indexed: 01/08/2023] Open
Abstract
Background Retrotransposons are one of the oldest evolutionary forces shaping mammalian genomes, with the ability to mobilize from one genomic location to another. This mobilization is also a significant factor in human disease. The only autonomous human retroelement, L1, has propagated to make up 17% of the human genome, accumulating over 500,000 copies. The majority of these loci are truncated or defective with only a few reported to remain capable of retrotransposition. We have previously published a strand-specific RNA-Seq bioinformatics approach to stringently identify at the locus-specific level the few expressed full-length L1s using cytoplasmic RNA. With growing repositories of RNA-Seq data, there is potential to mine these datasets to identify and study expressed L1s at single-locus resolution, although many datasets are not strand-specific or not generated from cytoplasmic RNA. Results We developed whole-cell, cytoplasmic and nuclear RNA-Seq datasets from 22Rv1 prostate cancer cells to test the influence of different preparations on the quality and effort needed to measure L1 expression. We found that there was minimal data loss in the identification of full-length expressed L1 s using whole cell, strand-specific RNA-Seq data compared to cytoplasmic, strand-specific RNA-Seq data. However, this was only possible with an increased amount of manual curation of the bioinformatics output to eliminate increased background. About half of the data was lost when the sequenced datasets were non-strand specific. Conclusions The results of these studies demonstrate that with rigorous manual curation the utilization of stranded RNA-Seq datasets allow identification of expressed L1 loci from either cytoplasmic or whole-cell RNA-Seq datasets.
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Affiliation(s)
- Tiffany Kaul
- 1Tulane Cancer Center, Tulane Health Sciences Center, 1700 Tulane Ave, New Orleans, LA 70112 USA
| | - Maria E Morales
- 1Tulane Cancer Center, Tulane Health Sciences Center, 1700 Tulane Ave, New Orleans, LA 70112 USA
| | - Alton O Sartor
- 1Tulane Cancer Center, Tulane Health Sciences Center, 1700 Tulane Ave, New Orleans, LA 70112 USA.,2Section of Hematology and Oncology, Department of Medicine, Tulane School of Medicine, 1430 Tulane Ave, New Orleans, LA 70112 USA
| | - Victoria P Belancio
- 1Tulane Cancer Center, Tulane Health Sciences Center, 1700 Tulane Ave, New Orleans, LA 70112 USA.,3Department of Structural and Cellular Biology, Tulane School of Medicine, 1430 Tulane Ave, New Orleans, 70112 USA
| | - Prescott Deininger
- 1Tulane Cancer Center, Tulane Health Sciences Center, 1700 Tulane Ave, New Orleans, LA 70112 USA.,4Department of Epidemiology, Tulane School of Public Health and Tropical Medicine, New Orleans, LA 70112 USA
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