1
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George Warren W, Osborn M, Yates A, O'Sullivan SE. The emerging role of fatty acid binding protein 7 (FABP7) in cancers. Drug Discov Today 2024; 29:103980. [PMID: 38614160 DOI: 10.1016/j.drudis.2024.103980] [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] [Received: 12/07/2023] [Revised: 03/27/2024] [Accepted: 04/05/2024] [Indexed: 04/15/2024]
Abstract
Fatty acid binding protein 7 (FABP7) is an intracellular protein involved in the uptake, transportation, metabolism, and storage of fatty acids (FAs). FABP7 is upregulated up to 20-fold in multiple cancers, usually correlated with poor prognosis. FABP7 silencing or pharmacological inhibition suggest FABP7 promotes cell growth, migration, invasion, colony and spheroid formation/increased size, lipid uptake, and lipid droplet formation. Xenograft studies show that suppression of FABP7 inhibits tumour formation and tumour growth, and improves host survival. The molecular mechanisms involve promotion of FA uptake, lipid droplets, signalling [focal adhesion kinase (FAK), proto-oncogene tyrosine-protein kinase Src (Src), mitogen-activated protein kinase kinase/p-extracellular signal-regulated kinase (MEK/ERK), and Wnt/β-catenin], hypoxia-inducible factor 1-alpha (Hif1α), vascular endothelial growth factor A/prolyl 4-hydroxylase subunit alpha-1 (VEGFA/P4HA1), snail family zinc finger 1 (Snail1), and twist-related protein 1 (Twist1). The oncogenic capacity of FABP7 makes it a promising pharmacological target for future cancer treatments.
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Affiliation(s)
| | - Myles Osborn
- Artelo Biosciences Limited, Alderley Park, Cheshire, UK
| | - Andrew Yates
- Artelo Biosciences Limited, Alderley Park, Cheshire, UK
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2
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Honda S, Hatamura M, Kunimoto Y, Ikeda S, Minami N. Chimeric PRMT6 protein produced by an endogenous retrovirus promoter regulates cell fate decision in mouse preimplantation embryos†. Biol Reprod 2024; 110:698-710. [PMID: 38196172 DOI: 10.1093/biolre/ioae002] [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: 05/29/2023] [Revised: 10/11/2023] [Accepted: 01/07/2023] [Indexed: 01/11/2024] Open
Abstract
Murine endogenous retrovirus with leucine tRNA primer, also known as MERVL, is expressed during zygotic genome activation in mammalian embryos. Here we show that protein arginine N-methyltransferase 6 (Prmt6) forms a chimeric transcript with MT2B2, one of the long terminal repeat sequences of murine endogenous retrovirus with leucine tRNA primer, and is translated into an elongated chimeric protein (PRMT6MT2B2) whose function differs from that of the canonical PRMT6 protein (PRMT6CAN) in mouse preimplantation embryos. Overexpression of PRMT6CAN in fibroblast cells increased asymmetric dimethylation of the third arginine residue of both histone H2A (H2AR3me2a) and histone H4 (H4R3me2a), while overexpression of PRMT6MT2B2 increased only H2AR3me2a. In addition, overexpression of PRMT6MT2B2 in one blastomere of mouse two-cell embryos promoted cell proliferation and differentiation of the blastomere into epiblast cells at the blastocyst stage, while overexpression of PRMT6CAN repressed cell proliferation. This is the first report of the translation of a chimeric protein (PRMT6MT2B2) in mouse preimplantation embryos. Our results suggest that analyzing chimeric transcripts with murine endogenous retrovirus with leucine tRNA primer will provide insight into the relationship between zygotic genome activation and subsequent intra- and extra-cellular lineage determination.
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Affiliation(s)
- Shinnosuke Honda
- Laboratory of Reproductive Biology, Graduate School of Agriculture, Kyoto University, Kyoto, Japan
| | - Maho Hatamura
- Laboratory of Reproductive Biology, Graduate School of Agriculture, Kyoto University, Kyoto, Japan
| | - Yuri Kunimoto
- Laboratory of Reproductive Biology, Graduate School of Agriculture, Kyoto University, Kyoto, Japan
| | - Shuntaro Ikeda
- Laboratory of Reproductive Biology, Graduate School of Agriculture, Kyoto University, Kyoto, Japan
| | - Naojiro Minami
- Laboratory of Reproductive Biology, Graduate School of Agriculture, Kyoto University, Kyoto, Japan
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3
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Chen M, Huang X, Wang C, Wang S, Jia L, Li L. Endogenous retroviral solo-LTRs in human genome. Front Genet 2024; 15:1358078. [PMID: 38606358 PMCID: PMC11007075 DOI: 10.3389/fgene.2024.1358078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Accepted: 03/04/2024] [Indexed: 04/13/2024] Open
Abstract
Human endogenous retroviruses (HERVs) are derived from the infection and integration of exogenetic retroviruses. HERVs account for 8% of human genome, and the majority of HERVs are solitary LTRs (solo-LTRs) due to homologous recombination. Multiple findings have showed that solo-LTRs could provide an enormous reservoir of transcriptional regulatory sequences involved in diverse biological processes, especially carcinogenesis and cancer development. The link between solo-LTRs and human diseases still remains poorly understood. This review focuses on the regulatory modules of solo-LTRs, which contribute greatly to the diversification and evolution of human genes. More importantly, although inactivating mutations, insertions and deletions have been identified in solo-LTRs, the inherited regulatory elements of solo-LTRs initiate the expression of chimeric lncRNA transcripts, which have been reported to play crucial roles in human health and disease. These findings provide valuable insights into the evolutionary and functional mechanisms underlying the presence of HERVs in human genome. Taken together, in this review, we will present evidences showing the regulatory and encoding capacity of solo-LTRs as well as the significant impact on various aspects of human biology.
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Affiliation(s)
- Mingyue Chen
- National 111 Center for Cellular Regulation and Molecular Pharmaceutics, Key Laboratory of Fermentation Engineering, Hubei University of Technology, Wuhan, Hubei, China
| | - Xiaolong Huang
- National 111 Center for Cellular Regulation and Molecular Pharmaceutics, Key Laboratory of Fermentation Engineering, Hubei University of Technology, Wuhan, Hubei, China
| | - Chunlei Wang
- Department of Microbiology, School of Basic Medicine, Anhui Medical University, Hefei, Anhui, China
- Department of Virology, Beijing Institute of Microbiology and Epidemiology, Beijing, China
- State Key Laboratory of Pathogen and Biosecurity, Beijing, China
| | - Shibo Wang
- National 111 Center for Cellular Regulation and Molecular Pharmaceutics, Key Laboratory of Fermentation Engineering, Hubei University of Technology, Wuhan, Hubei, China
| | - Lei Jia
- Department of Virology, Beijing Institute of Microbiology and Epidemiology, Beijing, China
- State Key Laboratory of Pathogen and Biosecurity, Beijing, China
| | - Lin Li
- Department of Virology, Beijing Institute of Microbiology and Epidemiology, Beijing, China
- State Key Laboratory of Pathogen and Biosecurity, Beijing, China
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4
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Dopkins N, Nixon DF. Activation of human endogenous retroviruses and its physiological consequences. Nat Rev Mol Cell Biol 2024; 25:212-222. [PMID: 37872387 DOI: 10.1038/s41580-023-00674-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/27/2023] [Indexed: 10/25/2023]
Abstract
Human endogenous retroviruses (HERVs) are abundant sequences that persist within the human genome as remnants of ancient retroviral infections. These sequences became fixed and accumulate mutations or deletions over time. HERVs have affected human evolution and physiology by providing a unique repertoire of coding and non-coding sequences to the genome. In healthy individuals, HERVs participate in immune responses, formation of syncytiotrophoblasts and cell-fate specification. In this Review, we discuss how endogenized retroviral motifs and regulatory sequences have been co-opted into human physiology and how they are tightly regulated. Infections and mutations can derail this regulation, leading to differential HERV expression, which may contribute to pathologies including neurodegeneration, pathological inflammation and oncogenesis. Emerging evidence demonstrates that HERVs are crucial to human health and represent an understudied facet of many diseases, and we therefore argue that investigating their fundamental properties could improve existing therapies and help develop novel therapeutic strategies.
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Affiliation(s)
- Nicholas Dopkins
- Division of Infectious Diseases, Department of Medicine, Weill Cornell Medicine, New York, NY, USA.
| | - Douglas F Nixon
- Division of Infectious Diseases, Department of Medicine, Weill Cornell Medicine, New York, NY, USA.
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5
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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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6
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Singh M, Leddy SM, Iñiguez LP, Bendall ML, Nixon DF, Feschotte C. Transposable elements may enhance antiviral resistance in HIV-1 elite controllers. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.11.571123. [PMID: 38168352 PMCID: PMC10760019 DOI: 10.1101/2023.12.11.571123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
Less than 0.5% of people living with HIV-1 are elite controllers (ECs) - individuals who have a replication-competent viral reservoir in their CD4+ T cells but maintain undetectable plasma viremia without the help of antiretroviral therapy. While the EC CD4+ T cell transcriptome has been investigated for gene expression signatures associated with disease progression (or, in this case, a lack thereof), the expression and regulatory activity of transposable elements (TEs) in ECs has not been explored. Yet previous studies have established that TEs can directly impact the immune response to pathogens, including HIV-1. Thus, we hypothesize that the regulatory activities of TEs could contribute to the natural resistance of ECs against HIV-1. We perform a TE-centric analysis of previously published multi-omics data derived from EC individuals and other populations. We find that the CD4+ T cell transcriptome and retrotranscriptome of ECs are distinct from healthy controls, treated patients, and viremic progressors. However, there is a substantial level of transcriptomic heterogeneity among ECs. We categorize individuals with distinct chromatin accessibility and expression profiles into four clusters within the EC group, each possessing unique repertoires of TEs and antiviral factors. Notably, several TE families with known immuno-regulatory activity are differentially expressed among ECs. Their transcript levels in ECs positively correlate with their chromatin accessibility and negatively correlate with the expression of their KRAB zinc-finger (KZNF) repressors. This coordinated variation is seen at the level of individual TE loci likely acting or, in some cases, known to act as cis-regulatory elements for nearby genes involved in the immune response and HIV-1 restriction. Based on these results, we propose that the EC phenotype is driven in part by the reduced availability of specific KZNF proteins to repress TE-derived cis-regulatory elements for antiviral genes, thereby heightening their basal level of resistance to HIV-1 infection. Our study reveals considerable heterogeneity in the CD4+ T cell transcriptome of ECs, including variable expression of TEs and their KZNF controllers, that must be taken into consideration to decipher the mechanisms enabling HIV-1 control.
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Affiliation(s)
- Manvendra Singh
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, USA
- Clinical Neuroscience, Max Planck Institute for Multidisciplinary Sciences, City Campus, Göttingen, Germany
| | - Sabrina M Leddy
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, USA
| | - Luis Pedro Iñiguez
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Matthew L Bendall
- Division of Infectious Diseases, Department of Medicine, Weill Cornell Medicine, New York, NY, USA
| | - Douglas F Nixon
- Division of Infectious Diseases, Department of Medicine, Weill Cornell Medicine, New York, NY, USA
| | - Cédric Feschotte
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, USA
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7
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Oliveira DS, Fablet M, Larue A, Vallier A, Carareto CA, Rebollo R, Vieira C. ChimeraTE: a pipeline to detect chimeric transcripts derived from genes and transposable elements. Nucleic Acids Res 2023; 51:9764-9784. [PMID: 37615575 PMCID: PMC10570057 DOI: 10.1093/nar/gkad671] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Revised: 07/25/2023] [Accepted: 08/09/2023] [Indexed: 08/25/2023] Open
Abstract
Transposable elements (TEs) produce structural variants and are considered an important source of genetic diversity. Notably, TE-gene fusion transcripts, i.e. chimeric transcripts, have been associated with adaptation in several species. However, the identification of these chimeras remains hindered due to the lack of detection tools at a transcriptome-wide scale, and to the reliance on a reference genome, even though different individuals/cells/strains have different TE insertions. Therefore, we developed ChimeraTE, a pipeline that uses paired-end RNA-seq reads to identify chimeric transcripts through two different modes. Mode 1 is the reference-guided approach that employs canonical genome alignment, and Mode 2 identifies chimeras derived from fixed or insertionally polymorphic TEs without any reference genome. We have validated both modes using RNA-seq data from four Drosophila melanogaster wild-type strains. We found ∼1.12% of all genes generating chimeric transcripts, most of them from TE-exonized sequences. Approximately ∼23% of all detected chimeras were absent from the reference genome, indicating that TEs belonging to chimeric transcripts may be recent, polymorphic insertions. ChimeraTE is the first pipeline able to automatically uncover chimeric transcripts without a reference genome, consisting of two running Modes that can be used as a tool to investigate the contribution of TEs to transcriptome plasticity.
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Affiliation(s)
- Daniel S Oliveira
- São Paulo State University (Unesp), Institute of Biosciences, Humanities and Exact Sciences, São José do Rio Preto, SP, Brazil
- Laboratoire de Biométrie et Biologie Evolutive, Université Lyon 1, CNRS, UMR5558, Villeurbanne, Rhone-Alpes, 69100, France
| | - Marie Fablet
- Laboratoire de Biométrie et Biologie Evolutive, Université Lyon 1, CNRS, UMR5558, Villeurbanne, Rhone-Alpes, 69100, France
- Institut Universitaire de France (IUF), Paris, Île-de-FranceF-75231, France
| | - Anaïs Larue
- Laboratoire de Biométrie et Biologie Evolutive, Université Lyon 1, CNRS, UMR5558, Villeurbanne, Rhone-Alpes, 69100, France
- Univ Lyon, INRAE, INSA-Lyon, BF2I, UMR 203, 69621 Villeurbanne, France
| | - Agnès Vallier
- Univ Lyon, INRAE, INSA-Lyon, BF2I, UMR 203, 69621 Villeurbanne, France
| | - Claudia M A Carareto
- São Paulo State University (Unesp), Institute of Biosciences, Humanities and Exact Sciences, São José do Rio Preto, SP, Brazil
| | - Rita Rebollo
- Univ Lyon, INRAE, INSA-Lyon, BF2I, UMR 203, 69621 Villeurbanne, France
| | - Cristina Vieira
- Laboratoire de Biométrie et Biologie Evolutive, Université Lyon 1, CNRS, UMR5558, Villeurbanne, Rhone-Alpes, 69100, France
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8
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Karttunen K, Patel D, Xia J, Fei L, Palin K, Aaltonen L, Sahu B. Transposable elements as tissue-specific enhancers in cancers of endodermal lineage. Nat Commun 2023; 14:5313. [PMID: 37658059 PMCID: PMC10474299 DOI: 10.1038/s41467-023-41081-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Accepted: 08/23/2023] [Indexed: 09/03/2023] Open
Abstract
Transposable elements (TE) are repetitive genomic elements that harbor binding sites for human transcription factors (TF). A regulatory role for TEs has been suggested in embryonal development and diseases such as cancer but systematic investigation of their functions has been limited by their widespread silencing in the genome. Here, we utilize unbiased massively parallel reporter assay data using a whole human genome library to identify TEs with functional enhancer activity in two human cancer types of endodermal lineage, colorectal and liver cancers. We show that the identified TE enhancers are characterized by genomic features associated with active enhancers, such as epigenetic marks and TF binding. Importantly, we identify distinct TE subfamilies that function as tissue-specific enhancers, namely MER11- and LTR12-elements in colon and liver cancers, respectively. These elements are bound by distinct TFs in each cell type, and they have predicted associations to differentially expressed genes. In conclusion, these data demonstrate how different cancer types can utilize distinct TEs as tissue-specific enhancers, paving the way for comprehensive understanding of the role of TEs as bona fide enhancers in the cancer genomes.
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Affiliation(s)
- Konsta Karttunen
- Applied Tumor Genomics Program, Research Programs Unit, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Divyesh Patel
- Applied Tumor Genomics Program, Research Programs Unit, Faculty of Medicine, University of Helsinki, Helsinki, Finland
- iCAN Digital Precision Cancer Medicine Flagship, University of Helsinki, Helsinki, Finland
| | - Jihan Xia
- Applied Tumor Genomics Program, Research Programs Unit, Faculty of Medicine, University of Helsinki, Helsinki, Finland
- iCAN Digital Precision Cancer Medicine Flagship, University of Helsinki, Helsinki, Finland
| | - Liangru Fei
- Applied Tumor Genomics Program, Research Programs Unit, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Kimmo Palin
- Applied Tumor Genomics Program, Research Programs Unit, Faculty of Medicine, University of Helsinki, Helsinki, Finland
- iCAN Digital Precision Cancer Medicine Flagship, University of Helsinki, Helsinki, Finland
| | - Lauri Aaltonen
- Applied Tumor Genomics Program, Research Programs Unit, Faculty of Medicine, University of Helsinki, Helsinki, Finland
- iCAN Digital Precision Cancer Medicine Flagship, University of Helsinki, Helsinki, Finland
| | - Biswajyoti Sahu
- Applied Tumor Genomics Program, Research Programs Unit, Faculty of Medicine, University of Helsinki, Helsinki, Finland.
- iCAN Digital Precision Cancer Medicine Flagship, University of Helsinki, Helsinki, Finland.
- Medicum, Faculty of Medicine, University of Helsinki, Helsinki, Finland.
- Centre for Molecular Medicine Norway, University of Oslo, Oslo, Norway.
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9
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Abstract
Fatty acid-binding proteins (FABPs) are small lipid-binding proteins abundantly expressed in tissues that are highly active in fatty acid (FA) metabolism. Ten mammalian FABPs have been identified, with tissue-specific expression patterns and highly conserved tertiary structures. FABPs were initially studied as intracellular FA transport proteins. Further investigation has demonstrated their participation in lipid metabolism, both directly and via regulation of gene expression, and in signaling within their cells of expression. There is also evidence that they may be secreted and have functional impact via the circulation. It has also been shown that the FABP ligand binding repertoire extends beyond long-chain FAs and that their functional properties also involve participation in systemic metabolism. This article reviews the present understanding of FABP functions and their apparent roles in disease, particularly metabolic and inflammation-related disorders and cancers.
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Affiliation(s)
- Judith Storch
- Department of Nutritional Sciences and Rutgers Center for Lipid Research, Rutgers University, New Brunswick, New Jersey, United States;
| | - Betina Corsico
- Instituto de Investigaciones Bioquímicas de La Plata, CONICET-UNLP, Facultad de Ciencias Médicas, La Plata, Argentina;
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10
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Singh B, Dopkins N, Fei T, Marston JL, Michael S, Reyes-Gopar H, Curty G, Heymann JJ, Chadburn A, Martin P, Leal FE, Cesarman E, Nixon DF, Bendall ML. Locus specific human endogenous retroviruses reveal new lymphoma subtypes. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.08.544208. [PMID: 37333202 PMCID: PMC10274920 DOI: 10.1101/2023.06.08.544208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/20/2023]
Abstract
The heterogeneity of cancers are driven by diverse mechanisms underlying oncogenesis such as differential 'cell-of-origin' (COO) progenitors, mutagenesis, and viral infections. Classification of B-cell lymphomas have been defined by considering these characteristics. However, the expression and contribution of transposable elements (TEs) to B cell lymphoma oncogenesis or classification have been overlooked. We hypothesized that incorporating TE signatures would increase the resolution of B-cell identity during healthy and malignant conditions. Here, we present the first comprehensive, locus-specific characterization of TE expression in benign germinal center (GC) B-cells, diffuse large B-cell lymphoma (DLBCL), Epstein-Barr virus (EBV)-positive and EBV-negative Burkitt lymphoma (BL), and follicular lymphoma (FL). Our findings demonstrate unique human endogenous retrovirus (HERV) signatures in the GC and lymphoma subtypes whose activity can be used in combination with gene expression to define B-cell lineage in lymphoid malignancies, highlighting the potential of retrotranscriptomic analyses as a tool in lymphoma classification, diagnosis, and the identification of novel treatment groups.
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Affiliation(s)
- Bhavya Singh
- Division of Infectious Diseases, Department of Medicine, Weill Cornell Medicine, New York, NY, USA
| | - Nicholas Dopkins
- Division of Infectious Diseases, Department of Medicine, Weill Cornell Medicine, New York, NY, USA
| | - Tongyi Fei
- Division of Infectious Diseases, Department of Medicine, Weill Cornell Medicine, New York, NY, USA
| | - Jez L. Marston
- Division of Infectious Diseases, Department of Medicine, Weill Cornell Medicine, New York, NY, USA
| | - Stephanie Michael
- Division of Infectious Diseases, Department of Medicine, Weill Cornell Medicine, New York, NY, USA
| | - Helena Reyes-Gopar
- Programa de Doctorado en Ciencias Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico
- Departamento de Genómica Computacional, Instituto Nacional de Medicina Genómica, Mexico City, Mexico
| | - Gislaine Curty
- Brazilian National Cancer Institute (INCA), Rio de Janeiro, Brazil
| | - Jonas J. Heymann
- Department of Pathology and Laboratory Medicine, Weill Cornell Medicine, New York, NY, USA
| | - Amy Chadburn
- Department of Pathology and Laboratory Medicine, Weill Cornell Medicine, New York, NY, USA
| | - Peter Martin
- Division of Hematology and Medical Oncology, Weill Cornell Medicine, New York, NY, USA
| | - Fabio E. Leal
- Brazilian National Cancer Institute (INCA), Rio de Janeiro, Brazil
| | - Ethel Cesarman
- Department of Pathology and Laboratory Medicine, Weill Cornell Medicine, New York, NY, USA
| | - Douglas F. Nixon
- Division of Infectious Diseases, Department of Medicine, Weill Cornell Medicine, New York, NY, USA
| | - Matthew L. Bendall
- Division of Infectious Diseases, Department of Medicine, Weill Cornell Medicine, New York, NY, USA
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11
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Shah NM, Jang HJ, Liang Y, Maeng JH, Tzeng SC, Wu A, Basri NL, Qu X, Fan C, Li A, Katz B, Li D, Xing X, Evans BS, Wang T. Pan-cancer analysis identifies tumor-specific antigens derived from transposable elements. Nat Genet 2023; 55:631-639. [PMID: 36973455 DOI: 10.1038/s41588-023-01349-3] [Citation(s) in RCA: 35] [Impact Index Per Article: 35.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Accepted: 02/23/2023] [Indexed: 03/29/2023]
Abstract
Cryptic promoters within transposable elements (TEs) can be transcriptionally reactivated in tumors to create new TE-chimeric transcripts, which can produce immunogenic antigens. We performed a comprehensive screen for these TE exaptation events in 33 TCGA tumor types, 30 GTEx adult tissues and 675 cancer cell lines, and identified 1,068 TE-exapted candidates with the potential to generate shared tumor-specific TE-chimeric antigens (TS-TEAs). Whole-lysate and HLA-pulldown mass spectrometry data confirmed that TS-TEAs are presented on the surface of cancer cells. In addition, we highlight tumor-specific membrane proteins transcribed from TE promoters that constitute aberrant epitopes on the extracellular surface of cancer cells. Altogether, we showcase the high pan-cancer prevalence of TS-TEAs and atypical membrane proteins that could potentially be therapeutically exploited and targeted.
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Affiliation(s)
- Nakul M Shah
- Department of Genetics, Washington University School of Medicine, St. Louis, MO, USA
- The Edison Family Center for Genome Sciences and Systems Biology, Washington University School of Medicine, St. Louis, MO, USA
| | - H Josh Jang
- Department of Genetics, Washington University School of Medicine, St. Louis, MO, USA
- The Edison Family Center for Genome Sciences and Systems Biology, Washington University School of Medicine, St. Louis, MO, USA
- Department of Epigenetics, Van Andel Institute, Grand Rapids, MI, USA
| | - Yonghao Liang
- Department of Genetics, Washington University School of Medicine, St. Louis, MO, USA
- The Edison Family Center for Genome Sciences and Systems Biology, Washington University School of Medicine, St. Louis, MO, USA
| | - Ju Heon Maeng
- Department of Genetics, Washington University School of Medicine, St. Louis, MO, USA
- The Edison Family Center for Genome Sciences and Systems Biology, Washington University School of Medicine, St. Louis, MO, USA
| | | | - Angela Wu
- Department of Genetics, Washington University School of Medicine, St. Louis, MO, USA
- The Edison Family Center for Genome Sciences and Systems Biology, Washington University School of Medicine, St. Louis, MO, USA
| | - Noah L Basri
- Department of Genetics, Washington University School of Medicine, St. Louis, MO, USA
- The Edison Family Center for Genome Sciences and Systems Biology, Washington University School of Medicine, St. Louis, MO, USA
| | - Xuan Qu
- Department of Genetics, Washington University School of Medicine, St. Louis, MO, USA
- The Edison Family Center for Genome Sciences and Systems Biology, Washington University School of Medicine, St. Louis, MO, USA
| | - Changxu Fan
- Department of Genetics, Washington University School of Medicine, St. Louis, MO, USA
- The Edison Family Center for Genome Sciences and Systems Biology, Washington University School of Medicine, St. Louis, MO, USA
| | - Amy Li
- Department of Genetics, Washington University School of Medicine, St. Louis, MO, USA
- The Edison Family Center for Genome Sciences and Systems Biology, Washington University School of Medicine, St. Louis, MO, USA
| | - Benjamin Katz
- Department of Genetics, Washington University School of Medicine, St. Louis, MO, USA
- The Edison Family Center for Genome Sciences and Systems Biology, Washington University School of Medicine, St. Louis, MO, USA
| | - Daofeng Li
- Department of Genetics, Washington University School of Medicine, St. Louis, MO, USA
- The Edison Family Center for Genome Sciences and Systems Biology, Washington University School of Medicine, St. Louis, MO, USA
| | - Xiaoyun Xing
- Department of Genetics, Washington University School of Medicine, St. Louis, MO, USA
- The Edison Family Center for Genome Sciences and Systems Biology, Washington University School of Medicine, St. Louis, MO, USA
| | | | - Ting Wang
- Department of Genetics, Washington University School of Medicine, St. Louis, MO, USA.
- The Edison Family Center for Genome Sciences and Systems Biology, Washington University School of Medicine, St. Louis, MO, USA.
- McDonnell Genome Institute, Washington University School of Medicine, St. Louis, MO, USA.
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12
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Stricker E, Peckham-Gregory EC, Scheurer ME. HERVs and Cancer-A Comprehensive Review of the Relationship of Human Endogenous Retroviruses and Human Cancers. Biomedicines 2023; 11:936. [PMID: 36979914 PMCID: PMC10046157 DOI: 10.3390/biomedicines11030936] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Revised: 03/03/2023] [Accepted: 03/10/2023] [Indexed: 03/30/2023] Open
Abstract
Genomic instability and genetic mutations can lead to exhibition of several cancer hallmarks in affected cells such as sustained proliferative signaling, evasion of growth suppression, activated invasion, deregulation of cellular energetics, and avoidance of immune destruction. Similar biological changes have been observed to be a result of pathogenic viruses and, in some cases, have been linked to virus-induced cancers. Human endogenous retroviruses (HERVs), once external pathogens, now occupy more than 8% of the human genome, representing the merge of genomic and external factors. In this review, we outline all reported effects of HERVs on cancer development and discuss the HERV targets most suitable for cancer treatments as well as ongoing clinical trials for HERV-targeting drugs. We reviewed all currently available reports of the effects of HERVs on human cancers including solid tumors, lymphomas, and leukemias. Our review highlights the central roles of HERV genes, such as gag, env, pol, np9, and rec in immune regulation, checkpoint blockade, cell differentiation, cell fusion, proliferation, metastasis, and cell transformation. In addition, we summarize the involvement of HERV long terminal repeat (LTR) regions in transcriptional regulation, creation of fusion proteins, expression of long non-coding RNAs (lncRNAs), and promotion of genome instability through recombination.
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Affiliation(s)
- Erik Stricker
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX 77047, USA
- Department of Pediatrics, Baylor College of Medicine, Houston, TX 77047, USA
| | | | - Michael E. Scheurer
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX 77047, USA
- Department of Pediatrics, Baylor College of Medicine, Houston, TX 77047, USA
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13
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Dominant role of DNA methylation over H3K9me3 for IAP silencing in endoderm. Nat Commun 2022; 13:5447. [PMID: 36123357 PMCID: PMC9485127 DOI: 10.1038/s41467-022-32978-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Accepted: 08/25/2022] [Indexed: 12/03/2022] Open
Abstract
Silencing of endogenous retroviruses (ERVs) is largely mediated by repressive chromatin modifications H3K9me3 and DNA methylation. On ERVs, these modifications are mainly deposited by the histone methyltransferase Setdb1 and by the maintenance DNA methyltransferase Dnmt1. Knock-out of either Setdb1 or Dnmt1 leads to ERV de-repression in various cell types. However, it is currently not known if H3K9me3 and DNA methylation depend on each other for ERV silencing. Here we show that conditional knock-out of Setdb1 in mouse embryonic endoderm results in ERV de-repression in visceral endoderm (VE) descendants and does not occur in definitive endoderm (DE). Deletion of Setdb1 in VE progenitors results in loss of H3K9me3 and reduced DNA methylation of Intracisternal A-particle (IAP) elements, consistent with up-regulation of this ERV family. In DE, loss of Setdb1 does not affect H3K9me3 nor DNA methylation, suggesting Setdb1-independent pathways for maintaining these modifications. Importantly, Dnmt1 knock-out results in IAP de-repression in both visceral and definitive endoderm cells, while H3K9me3 is unaltered. Thus, our data suggest a dominant role of DNA methylation over H3K9me3 for IAP silencing in endoderm cells. Our findings suggest that Setdb1-meditated H3K9me3 is not sufficient for IAP silencing, but rather critical for maintaining high DNA methylation. Silencing of endogenous retroviruses is crucial for maintaining transcriptional and genomic integrity of cells and is maintained by histone H3K9 methylation and/or DNA methylation in various cell types. Here the authors show that loss of DNA methyltransferase DNMT1 in endoderm results in ERV derepression while H3K9me3 is unaltered.
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14
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Zhang M, Zheng S, Liang JQ. Transcriptional and reverse transcriptional regulation of host genes by human endogenous retroviruses in cancers. Front Microbiol 2022; 13:946296. [PMID: 35928153 PMCID: PMC9343867 DOI: 10.3389/fmicb.2022.946296] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Accepted: 06/29/2022] [Indexed: 11/16/2022] Open
Abstract
Human endogenous retroviruses (HERVs) originated from ancient retroviral infections of germline cells millions of years ago and have evolved as part of the host genome. HERVs not only retain the capacity as retroelements but also regulate host genes. The expansion of HERVs involves transcription by RNA polymerase II, reverse transcription, and re-integration into the host genome. Fast progress in deep sequencing and functional analysis has revealed the importance of domesticated copies of HERVs, including their regulatory sequences, transcripts, and proteins in normal cells. However, evidence also suggests the involvement of HERVs in the development and progression of many types of cancer. Here we summarize the current state of knowledge about the expression of HERVs, transcriptional regulation of host genes by HERVs, and the functions of HERVs in reverse transcription and gene editing with their reverse transcriptase.
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Affiliation(s)
- Mengwen Zhang
- The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, China
- Ministry of Education Key Laboratory of Cancer Prevention and Intervention, Second Affiliated Hospital, Cancer Institute, Zhejiang University School of Medicine, Hangzhou, China
| | - Shu Zheng
- The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, China
- Ministry of Education Key Laboratory of Cancer Prevention and Intervention, Second Affiliated Hospital, Cancer Institute, Zhejiang University School of Medicine, Hangzhou, China
- *Correspondence: Shu Zheng,
| | - Jessie Qiaoyi Liang
- Department of Medicine and Therapeutics, Faculty of Medicine, Center for Gut Microbiota Research, Li Ka Shing Institute of Health Sciences, Shenzhen Research Institute, The Chinese University of Hong Kong, Hong Kong, Hong Kong SAR, China
- Jessie Qiaoyi Liang,
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15
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Grillo G, Lupien M. Cancer-associated chromatin variants uncover the oncogenic role of transposable elements. Curr Opin Genet Dev 2022; 74:101911. [PMID: 35487182 DOI: 10.1016/j.gde.2022.101911] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 03/08/2022] [Accepted: 03/24/2022] [Indexed: 11/26/2022]
Abstract
The vast array of cell states found across human tissue arises from chromatin variants, which correspond to segments of the genome, known as DNA elements, adopting a different chromatin state over cell state transitions. Oncogenesis stems from alterations to the chromatin states over DNA elements that result in cancer-associated chromatin variants. Here, we review how cancer-associated chromatin variants call attention to repetitive DNA elements, and guide the functional characterization of transposable elements to decode their role in oncogenesis. We further discuss prevailing opportunities in the study of repetitive DNA elements to move towards the 'complete cancer genome' goal for precision medicine in oncology.
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Affiliation(s)
- Giacomo Grillo
- Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario, Canada.
| | - Mathieu Lupien
- Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario, Canada; Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada; Ontario Institute for Cancer Research, Toronto, Ontario, Canada.
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16
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Schwarz R, Koch P, Wilbrandt J, Hoffmann S. Locus-specific expression analysis of transposable elements. Brief Bioinform 2021; 23:6400501. [PMID: 34664075 PMCID: PMC8769692 DOI: 10.1093/bib/bbab417] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 08/24/2021] [Accepted: 09/10/2021] [Indexed: 11/16/2022] Open
Abstract
Transposable elements (TEs) have been associated with many, frequently detrimental, biological roles. Consequently, the regulations of TEs, e.g. via DNA-methylation and histone modifications, are considered critical for maintaining genomic integrity and other functions. Still, the high-throughput study of TEs is usually limited to the family or consensus-sequence level because of alignment problems prompted by high-sequence similarities and short read lengths. To entirely comprehend the effects and reasons of TE expression, however, it is necessary to assess the TE expression at the level of individual instances. Our simulation study demonstrates that sequence similarities and short read lengths do not rule out the accurate assessment of (differential) expression of TEs at the instance-level. With only slight modifications to existing methods, TE expression analysis works surprisingly well for conventional paired-end sequencing data. We find that SalmonTE and Telescope can accurately tally a considerable amount of TE instances, allowing for differential expression recovery in model and non-model organisms.
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Affiliation(s)
- Robert Schwarz
- Computational Biology Group, Leibniz Institute on Aging - Fritz Lipmann Institute (FLI) Beutenbergstrasse 11, 07745 Jena, Germany
| | - Philipp Koch
- CF Life Science Computing, Leibniz Institute on Aging - Fritz Lipmann Institute (FLI) Beutenbergstrasse 11, 07745 Jena, Germany
| | - Jeanne Wilbrandt
- CF Life Science Computing, Leibniz Institute on Aging - Fritz Lipmann Institute (FLI) Beutenbergstrasse 11, 07745 Jena, Germany
| | - Steve Hoffmann
- Computational Biology Group, Leibniz Institute on Aging - Fritz Lipmann Institute (FLI) Beutenbergstrasse 11, 07745 Jena, Germany
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17
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Jiang JC, Rothnagel JA, Upton KR. Integrated transcription factor profiling with transcriptome analysis identifies L1PA2 transposons as global regulatory modulators in a breast cancer model. Sci Rep 2021; 11:8083. [PMID: 33850167 PMCID: PMC8044218 DOI: 10.1038/s41598-021-86395-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Accepted: 02/26/2021] [Indexed: 12/13/2022] Open
Abstract
While transposons are generally silenced in somatic tissues, many transposons escape epigenetic repression in epithelial cancers, become transcriptionally active and contribute to the regulation of human gene expression. We have developed a bioinformatic pipeline for the integrated analysis of transcription factor binding and transcriptomic data to identify transposon-derived promoters that are activated in specific diseases and developmental states. We applied this pipeline to a breast cancer model, and found that the L1PA2 transposon subfamily contributes abundant regulatory sequences to co-ordinated transcriptional regulation in breast cancer. Transcription factor profiling demonstrates that over 27% of L1PA2 transposons harbour co-localised binding sites of functionally interacting, cancer-associated transcription factors in MCF7 cells, a cell line used to model breast cancer. Transcriptomic analysis reveals that L1PA2 transposons also contribute transcription start sites to up-regulated transcripts in MCF7 cells, including some transcripts with established oncogenic properties. In addition, we verified the utility of our pipeline on other transposon subfamilies, as well as on leukemia and lung carcinoma cell lines. We demonstrate that the normally quiescent regulatory activities of transposons can be activated and alter the cancer transcriptome. In particular, the L1PA2 subfamily contributes abundant regulatory sequences, and likely plays a global role in modulating breast cancer transcriptional regulation. Understanding the regulatory impact of L1PA2 on breast cancer genomes provides additional insights into cancer genome regulation, and may provide novel biomarkers for disease diagnosis, prognosis and therapy.
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Affiliation(s)
- Jiayue-Clara Jiang
- School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, QLD, 4072, Australia
| | - Joseph A Rothnagel
- School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, QLD, 4072, Australia
| | - Kyle R Upton
- School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, QLD, 4072, Australia.
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18
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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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19
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Grundy EE, Diab N, Chiappinelli KB. Transposable element regulation and expression in cancer. FEBS J 2021; 289:1160-1179. [PMID: 33471418 DOI: 10.1111/febs.15722] [Citation(s) in RCA: 50] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 01/08/2021] [Accepted: 01/14/2021] [Indexed: 12/11/2022]
Abstract
Approximately 45% of the human genome is composed of transposable elements (TEs). Expression of these elements is tightly regulated during normal development. TEs may be expressed at high levels in embryonic stem cells but are epigenetically silenced in terminally differentiated cells. As part of the global 'epigenetic dysregulation' that cells undergo during transformation from normal to cancer, TEs can lose epigenetic silencing and become transcribed, and, in some cases, active. Here, we summarize recent advances detailing the consequences of TE activation in cancer and describe how these understudied residents of our genome can both aid tumorigenesis and potentially be harnessed for anticancer therapies.
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Affiliation(s)
- Erin E Grundy
- Department of Microbiology, Immunology, & Tropical Medicine, The George Washington University, Washington, DC, USA.,The GW Cancer Center, The George Washington University, Washington, DC, USA.,The Institute for Biomedical Sciences at The George Washington University, Washington, DC, USA
| | - Noor Diab
- Department of Microbiology, Immunology, & Tropical Medicine, The George Washington University, Washington, DC, USA.,The GW Cancer Center, The George Washington University, Washington, DC, USA
| | - Katherine B Chiappinelli
- Department of Microbiology, Immunology, & Tropical Medicine, The George Washington University, Washington, DC, USA.,The GW Cancer Center, The George Washington University, Washington, DC, USA
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20
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Lanciano S, Cristofari G. Measuring and interpreting transposable element expression. Nat Rev Genet 2020; 21:721-736. [PMID: 32576954 DOI: 10.1038/s41576-020-0251-y] [Citation(s) in RCA: 168] [Impact Index Per Article: 42.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/19/2020] [Indexed: 12/21/2022]
Abstract
Transposable elements (TEs) are insertional mutagens that contribute greatly to the plasticity of eukaryotic genomes, influencing the evolution and adaptation of species as well as physiology or disease in individuals. Measuring TE expression helps to understand not only when and where TE mobilization can occur but also how this process alters gene expression, chromatin accessibility or cellular signalling pathways. Although genome-wide gene expression assays such as RNA sequencing include transposon-derived transcripts, most computational analytical tools discard or misinterpret TE-derived reads. Emerging approaches are improving the identification of expressed TE loci and helping to discriminate TE transcripts that permit TE mobilization from chimeric gene-TE transcripts or pervasive transcription. Here we review the main challenges associated with the detection of TE expression, including mappability, insertional and internal sequence polymorphisms, and the diversity of the TE transcriptional landscape, as well as the different experimental and computational strategies to solve them.
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21
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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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22
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Jiang JC, Upton KR. Human transposons are an abundant supply of transcription factor binding sites and promoter activities in breast cancer cell lines. Mob DNA 2019; 10:16. [PMID: 31061680 PMCID: PMC6486989 DOI: 10.1186/s13100-019-0158-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Accepted: 04/01/2019] [Indexed: 12/22/2022] Open
Abstract
Background Transposable elements (TE) are commonly regarded as “junk DNA” with no apparent regulatory roles in the human genome. However, a growing body of evidence demonstrates that some TEs exhibit regulatory activities in a range of biological pathways and diseases, with notable examples in bile metabolism and innate immunity. TEs are typically suppressed by epigenetic modifications in healthy somatic tissues, which prevents both undesirable effects of insertional mutagenesis, and also unwanted gene activation. Interestingly, TEs are widely reported to be dysregulated in epithelial cancers, and while much attention has been paid to their effects on genome instability, relatively little has been reported on their effects on gene regulation. Here, we investigated the contribution of TEs to the transcriptional regulation in breast cancer cell lines. Results We found that a subset of TE subfamilies were enriched in oncogenic transcription factor binding sites and also harboured histone marks associated with active transcription, raising the possibility of these subfamilies playing a broad role in breast cancer transcriptional regulation. To directly assess promoter activity in triple negative breast cancer cell lines, we identified four breast cancer-associated genes with putative TE-derived promoters. TE deletion confirmed a contribution to promoter activity in all cases, and for two examples the promoter activity was almost completely contained within the TE. Conclusions Our findings demonstrate that TEs provide abundant oncogenic transcription factor binding sites in breast cancer and that individual TEs contain substantial promoter activity. Our findings provide further evidence for transcriptional regulation of human genes through TE exaptation by demonstrating the regulatory potential of TEs in multiple breast cancer cell lines. Electronic supplementary material The online version of this article (10.1186/s13100-019-0158-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Jiayue-Clara Jiang
- School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, QLD 4072 Australia
| | - Kyle R Upton
- School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, QLD 4072 Australia
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Siebenthall KT, Miller CP, Vierstra JD, Mathieu J, Tretiakova M, Reynolds A, Sandstrom R, Rynes E, Haugen E, Johnson A, Nelson J, Bates D, Diegel M, Dunn D, Frerker M, Buckley M, Kaul R, Zheng Y, Himmelfarb J, Ruohola-Baker H, Akilesh S. Integrated epigenomic profiling reveals endogenous retrovirus reactivation in renal cell carcinoma. EBioMedicine 2019; 41:427-442. [PMID: 30827930 PMCID: PMC6441874 DOI: 10.1016/j.ebiom.2019.01.063] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2018] [Revised: 01/30/2019] [Accepted: 01/31/2019] [Indexed: 02/08/2023] Open
Abstract
BACKGROUND Transcriptional dysregulation drives cancer formation but the underlying mechanisms are still poorly understood. Renal cell carcinoma (RCC) is the most common malignant kidney tumor which canonically activates the hypoxia-inducible transcription factor (HIF) pathway. Despite intensive study, novel therapeutic strategies to target RCC have been difficult to develop. Since the RCC epigenome is relatively understudied, we sought to elucidate key mechanisms underpinning the tumor phenotype and its clinical behavior. METHODS We performed genome-wide chromatin accessibility (DNase-seq) and transcriptome profiling (RNA-seq) on paired tumor/normal samples from 3 patients undergoing nephrectomy for removal of RCC. We incorporated publicly available data on HIF binding (ChIP-seq) in a RCC cell line. We performed integrated analyses of these high-resolution, genome-scale datasets together with larger transcriptomic data available through The Cancer Genome Atlas (TCGA). FINDINGS Though HIF transcription factors play a cardinal role in RCC oncogenesis, we found that numerous transcription factors with a RCC-selective expression pattern also demonstrated evidence of HIF binding near their gene body. Examination of chromatin accessibility profiles revealed that some of these transcription factors influenced the tumor's regulatory landscape, notably the stem cell transcription factor POU5F1 (OCT4). Elevated POU5F1 transcript levels were correlated with advanced tumor stage and poorer overall survival in RCC patients. Unexpectedly, we discovered a HIF-pathway-responsive promoter embedded within a endogenous retroviral long terminal repeat (LTR) element at the transcriptional start site of the PSOR1C3 long non-coding RNA gene upstream of POU5F1. RNA transcripts are induced from this promoter and read through PSOR1C3 into POU5F1 producing a novel POU5F1 transcript isoform. Rather than being unique to the POU5F1 locus, we found that HIF binds to several other transcriptionally active LTR elements genome-wide correlating with broad gene expression changes in RCC. INTERPRETATION Integrated transcriptomic and epigenomic analysis of matched tumor and normal tissues from even a small number of primary patient samples revealed remarkably convergent shared regulatory landscapes. Several transcription factors appear to act downstream of HIF including the potent stem cell transcription factor POU5F1. Dysregulated expression of POU5F1 is part of a larger pattern of gene expression changes in RCC that may be induced by HIF-dependent reactivation of dormant promoters embedded within endogenous retroviral LTRs.
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Affiliation(s)
- Kyle T Siebenthall
- Altius Institute for Biomedical Sciences, Seattle, WA 98121, United States
| | - Chris P Miller
- Department of Pathology, University of Washington, Seattle, WA 98195, United States
| | - Jeff D Vierstra
- Altius Institute for Biomedical Sciences, Seattle, WA 98121, United States
| | - Julie Mathieu
- Institute for Stem Cell and Regenerative Medicine, Seattle, WA 98109, United States; Department of Comparative Medicine, University of Washington, Seattle, WA 98195, United States
| | - Maria Tretiakova
- Department of Pathology, University of Washington, Seattle, WA 98195, United States
| | - Alex Reynolds
- Altius Institute for Biomedical Sciences, Seattle, WA 98121, United States
| | - Richard Sandstrom
- Altius Institute for Biomedical Sciences, Seattle, WA 98121, United States
| | - Eric Rynes
- Altius Institute for Biomedical Sciences, Seattle, WA 98121, United States
| | - Eric Haugen
- Altius Institute for Biomedical Sciences, Seattle, WA 98121, United States
| | - Audra Johnson
- Altius Institute for Biomedical Sciences, Seattle, WA 98121, United States
| | - Jemma Nelson
- Altius Institute for Biomedical Sciences, Seattle, WA 98121, United States
| | - Daniel Bates
- Altius Institute for Biomedical Sciences, Seattle, WA 98121, United States
| | - Morgan Diegel
- Altius Institute for Biomedical Sciences, Seattle, WA 98121, United States
| | - Douglass Dunn
- Altius Institute for Biomedical Sciences, Seattle, WA 98121, United States
| | - Mark Frerker
- Altius Institute for Biomedical Sciences, Seattle, WA 98121, United States
| | - Michael Buckley
- Altius Institute for Biomedical Sciences, Seattle, WA 98121, United States
| | - Rajinder Kaul
- Altius Institute for Biomedical Sciences, Seattle, WA 98121, United States
| | - Ying Zheng
- Department of Bioengineering, University of Washington, Seattle, WA 98195, United States; Kidney Research Institute, Seattle, WA 98104, United States
| | - Jonathan Himmelfarb
- Division of Nephrology, Department of Medicine, University of Washington, Seattle, WA 98195, United States; Kidney Research Institute, Seattle, WA 98104, United States
| | - Hannele Ruohola-Baker
- Department of Biochemistry, University of Washington, Seattle, WA 98195, United States; Institute for Stem Cell and Regenerative Medicine, Seattle, WA 98109, United States
| | - Shreeram Akilesh
- Department of Pathology, University of Washington, Seattle, WA 98195, United States; Kidney Research Institute, Seattle, WA 98104, United States.
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Bakshi A, Ekram MB, Kim J. High-Throughput Targeted Repeat Element Bisulfite Sequencing (HT-TREBS). Methods Mol Biol 2019; 1908:219-228. [PMID: 30649731 DOI: 10.1007/978-1-4939-9004-7_15] [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: 06/09/2023]
Abstract
High-throughput targeted repeat element bisulfite sequencing (HT-TREBS) is designed to assay the methylation level of individual retrotransposon loci of a targeted family, in a locus-specific manner, and on a genome-wide scale. Briefly, genomic DNA is sheared and ligated to Ion Torrent A adaptors (with methylated cytosines), followed by bisulfite-conversion, and amplification with primers designed to bind the targeted retrotransposon. Since the primers carry the Ion Torrent P1 adaptor as a 5'-extension, the amplified library is ready to be size-selected and sequenced on a next-generation sequencing platform. Once sequenced, each retrotransposon is mapped to a particular genomic locus, which is achieved through ensuring at least a 10-bp overlap with flanking unique sequence, followed by the calculation of methylation levels of the mapped retrotransposon using a BiQ Analyzer HT. A complete protocol for library construction as well as the bioinformatics for HT-TREBS is described in this chapter.
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Affiliation(s)
- Arundhati Bakshi
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA, USA
| | - Muhammad B Ekram
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA, USA
| | - Joomyeong Kim
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA, USA.
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Leung A, Trac C, Kato H, Costello KR, Chen Z, Natarajan R, Schones DE. LTRs activated by Epstein-Barr virus-induced transformation of B cells alter the transcriptome. Genome Res 2018; 28:1791-1798. [PMID: 30381291 PMCID: PMC6280761 DOI: 10.1101/gr.233585.117] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Accepted: 10/24/2018] [Indexed: 12/13/2022]
Abstract
Endogenous retroviruses (ERVs) are ancient viral elements that have accumulated in the genome through retrotransposition events. Although they have lost their ability to transpose, many of the long terminal repeats (LTRs) that originally flanked full-length ERVs maintain the ability to regulate transcription. While these elements are typically repressed in somatic cells, they can function as transcriptional enhancers and promoters when this repression is lost. Epstein-Barr virus (EBV), which transforms primary B cells into continuously proliferating cells, is a tumor virus associated with lymphomas. We report here that transformation of primary B cells by EBV leads to genome-wide activation of LTR enhancers and promoters. The activation of LTRs coincides with local DNA hypomethylation and binding by transcription factors such as RUNX3, EBF1, and EBNA2. The set of activated LTRs is unique to transformed B cells compared with other cell lines known to have activated LTRs. Furthermore, we found that LTR activation impacts the B cell transcriptome by up-regulating transcripts driven by cryptic LTR promoters. These transcripts include genes important to oncogenesis of Hodgkin lymphoma and other cancers, such as HUWE1/HECTH9 These data suggest that the activation of LTRs by EBV-induced transformation is important to the pathology of EBV-associated cancers. Altogether, our results indicate that EBV-induced transformation of B cells alters endogenous retroviral element activity, thereby impacting host gene regulatory networks and oncogenic potential.
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Affiliation(s)
- Amy Leung
- Department of Diabetes Complications and Metabolism, Beckman Research Institute, City of Hope, Duarte, California 91010, USA
| | - Candi Trac
- Department of Diabetes Complications and Metabolism, Beckman Research Institute, City of Hope, Duarte, California 91010, USA
| | - Hiroyuki Kato
- Department of Diabetes Complications and Metabolism, Beckman Research Institute, City of Hope, Duarte, California 91010, USA
| | - Kevin R Costello
- Department of Diabetes Complications and Metabolism, Beckman Research Institute, City of Hope, Duarte, California 91010, USA
- Irell and Manella Graduate School of Biological Sciences, City of Hope, Duarte, California 91010, USA
| | - Zhaoxia Chen
- Department of Diabetes Complications and Metabolism, Beckman Research Institute, City of Hope, Duarte, California 91010, USA
| | - Rama Natarajan
- Department of Diabetes Complications and Metabolism, Beckman Research Institute, City of Hope, Duarte, California 91010, USA
- Irell and Manella Graduate School of Biological Sciences, City of Hope, Duarte, California 91010, USA
| | - Dustin E Schones
- Department of Diabetes Complications and Metabolism, Beckman Research Institute, City of Hope, Duarte, California 91010, USA
- Irell and Manella Graduate School of Biological Sciences, City of Hope, Duarte, California 91010, USA
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White CH, Beliakova-Bethell N, Lada SM, Breen MS, Hurst TP, Spina CA, Richman DD, Frater J, Magiorkinis G, Woelk CH. Transcriptional Modulation of Human Endogenous Retroviruses in Primary CD4+ T Cells Following Vorinostat Treatment. Front Immunol 2018; 9:603. [PMID: 29706951 PMCID: PMC5906534 DOI: 10.3389/fimmu.2018.00603] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2017] [Accepted: 03/09/2018] [Indexed: 12/19/2022] Open
Abstract
The greatest obstacle to a cure for HIV is the provirus that integrates into the genome of the infected cell and persists despite antiretroviral therapy. A "shock and kill" approach has been proposed as a strategy for an HIV cure whereby drugs and compounds referred to as latency-reversing agents (LRAs) are used to "shock" the silent provirus into active replication to permit "killing" by virus-induced pathology or immune recognition. The LRA most utilized to date in clinical trials has been the histone deacetylase (HDAC) inhibitor-vorinostat. Potentially, pathological off-target effects of vorinostat may result from the activation of human endogenous retroviruses (HERVs), which share common ancestry with exogenous retroviruses including HIV. To explore the effects of HDAC inhibition on HERV transcription, an unbiased pharmacogenomics approach (total RNA-Seq) was used to evaluate HERV expression following the exposure of primary CD4+ T cells to a high dose of vorinostat. Over 2,000 individual HERV elements were found to be significantly modulated by vorinostat, whereby elements belonging to the ERVL family (e.g., LTR16C and LTR33) were predominantly downregulated, in contrast to LTR12 elements of the HERV-9 family, which exhibited the greatest signal, with the upregulation of 140 distinct elements. The modulation of three different LTR12 elements by vorinostat was confirmed by droplet digital PCR along a dose-response curve. The monitoring of LTR12 expression during clinical trials with vorinostat may be indicated to assess the impact of this HERV on the human genome and host immunity.
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Affiliation(s)
- Cory H. White
- Faculty of Medicine, University of Southampton, Southampton, Hants, United Kingdom
| | - Nadejda Beliakova-Bethell
- San Diego VA Medical Center and Veterans Medical Research Foundation, San Diego, CA, United States
- Department of Medicine, University of California San Diego, La Jolla, CA, United States
| | - Steven M. Lada
- San Diego VA Medical Center and Veterans Medical Research Foundation, San Diego, CA, United States
| | - Michael S. Breen
- Department of Genetic and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, United States
| | - Tara P. Hurst
- Department of Zoology, University of Oxford, Oxford, United Kingdom
| | - Celsa A. Spina
- San Diego VA Medical Center and Veterans Medical Research Foundation, San Diego, CA, United States
- Department of Pathology, University of California San Diego, La Jolla, CA, United States
| | - Douglas D. Richman
- San Diego VA Medical Center and Veterans Medical Research Foundation, San Diego, CA, United States
- Department of Medicine, University of California San Diego, La Jolla, CA, United States
- Department of Pathology, University of California San Diego, La Jolla, CA, United States
| | - John Frater
- Nuffield Department of Clinical Medicine, Peter Medawar Building for Pathogen Research, South Parks Road, Oxford, United Kingdom
| | | | - Christopher H. Woelk
- Faculty of Medicine, University of Southampton, Southampton, Hants, United Kingdom
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Kassiotis G, Stoye JP. Making a virtue of necessity: the pleiotropic role of human endogenous retroviruses in cancer. Philos Trans R Soc Lond B Biol Sci 2018; 372:rstb.2016.0277. [PMID: 28893944 PMCID: PMC5597744 DOI: 10.1098/rstb.2016.0277] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/09/2017] [Indexed: 12/18/2022] Open
Abstract
Like all other mammals, humans harbour an astonishing number of endogenous retroviruses (ERVs), as well as other retroelements, embedded in their genome. These remnants of ancestral germline infection with distinct exogenous retroviruses display various degrees of open reading frame integrity and replication capability. Modern day exogenous retroviruses, as well as the infectious predecessors of ERVs, are demonstrably oncogenic. Further, replication-competent ERVs continue to cause cancers in many other species of mammal. Moreover, human cancers are characterized by transcriptional activation of human endogenous retroviruses (HERVs). These observations conspire to incriminate HERVs as causative agents of human cancer. However, exhaustive investigation of cancer genomes suggests that HERVs have entirely lost the ability for re-infection and thus the potential for insertional mutagenic activity. Although there may be non-insertional mechanisms by which HERVs contribute to cancer development, recent evidence also uncovers potent anti-tumour activities exerted by HERV replication intermediates or protein products. On balance, it appears that HERVs, despite their oncogenic past, now represent potential targets for immune-mediated anti-tumour mechanisms. This article is part of the themed issue ‘Human oncogenic viruses’.
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Affiliation(s)
- George Kassiotis
- Retroviral Immunology, The Francis Crick Institute, London, UK .,Department of Medicine, Faculty of Medicine, Imperial College London, London, UK
| | - Jonathan P Stoye
- Retrovirus-Host Interactions, The Francis Crick Institute, London, UK .,Department of Medicine, Faculty of Medicine, Imperial College London, London, UK
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Cardelli M. The epigenetic alterations of endogenous retroelements in aging. Mech Ageing Dev 2018; 174:30-46. [PMID: 29458070 DOI: 10.1016/j.mad.2018.02.002] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Revised: 02/05/2018] [Accepted: 02/08/2018] [Indexed: 02/06/2023]
Abstract
Endogenous retroelements, transposons that mobilize through RNA intermediates, include some of the most abundant repetitive sequences of the human genome, such as Alu and LINE-1 sequences, and human endogenous retroviruses. Recent discoveries demonstrate that these mobile genetic elements not only act as intragenomic parasites, but also exert regulatory roles in living cells. The risk of genomic instability represented by endogenous retroelements is normally counteracted by a series of epigenetic control mechanisms which include, among the most important, CpG DNA methylation. Indeed, most of the genomic CpG sites subjected to DNA methylation in the nuclear DNA are carried by these repetitive elements. As other parts of the genome, endogenous retroelements and other transposable elements are subjected to deep epigenetic alterations during aging, repeatedly observed in the context of organismal and cellular senescence, in human and other species. This review summarizes the current status of knowledge about the epigenetic alterations occurring in this large, non-genic portion of the genome in aging and age-related conditions, with a focus on the causes and the possible functional consequences of these alterations.
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Affiliation(s)
- Maurizio Cardelli
- Advanced Technology Center for Aging Research, Scientific Technological Area, Italian National Research Center on Aging (INRCA), via Birarelli 8, 60121 Ancona, Italy.
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29
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Bustamante Rivera YY, Brütting C, Schmidt C, Volkmer I, Staege MS. Endogenous Retrovirus 3 - History, Physiology, and Pathology. Front Microbiol 2018; 8:2691. [PMID: 29379485 PMCID: PMC5775217 DOI: 10.3389/fmicb.2017.02691] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Accepted: 12/26/2017] [Indexed: 01/05/2023] Open
Abstract
Endogenous viral elements (EVE) seem to be present in all eukaryotic genomes. The composition of EVE varies between different species. The endogenous retrovirus 3 (ERV3) is one of these elements that is present only in humans and other Catarrhini. Conservation of ERV3 in most of the investigated Catarrhini and the expression pattern in normal tissues suggest a putative physiological role of ERV3. On the other hand, ERV3 has been implicated in the pathogenesis of auto-immunity and cancer. In the present review we summarize knowledge about this interesting EVE. We propose the model that expression of ERV3 (and probably other EVE loci) under pathological conditions might be part of a metazoan SOS response.
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Affiliation(s)
| | - Christine Brütting
- Department of Paediatrics I, Martin Luther University Halle-Wittenberg, Halle, Germany.,Department of Neurology, Martin Luther University Halle-Wittenberg, Halle, Germany
| | - Caroline Schmidt
- Department of Paediatrics I, Martin Luther University Halle-Wittenberg, Halle, Germany
| | - Ines Volkmer
- Department of Paediatrics I, Martin Luther University Halle-Wittenberg, Halle, Germany
| | - Martin S Staege
- Department of Paediatrics I, Martin Luther University Halle-Wittenberg, Halle, Germany
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Lock FE, Babaian A, Zhang Y, Gagnier L, Kuah S, Weberling A, Karimi MM, Mager DL. A novel isoform of IL-33 revealed by screening for transposable element promoted genes in human colorectal cancer. PLoS One 2017; 12:e0180659. [PMID: 28715472 PMCID: PMC5513427 DOI: 10.1371/journal.pone.0180659] [Citation(s) in RCA: 16] [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: 03/31/2017] [Accepted: 06/19/2017] [Indexed: 02/06/2023] Open
Abstract
Remnants of ancient transposable elements (TEs) are abundant in mammalian genomes. These sequences contain multiple regulatory motifs and hence are capable of influencing expression of host genes. TEs are known to be released from epigenetic repression and can become transcriptionally active in cancer. Such activation could also lead to lineage-inappropriate activation of oncogenes, as previously described in lymphomas. However, there are few reports of this mechanism occurring in non-blood cancers. Here, we re-analyzed whole transcriptome data from a large cohort of patients with colon cancer, compared to matched normal colon control samples, to detect genes or transcripts ectopically expressed through activation of TE promoters. Among many such transcripts, we identified six where the affected gene has described role in cancer and where the TE-driven gene mRNA is expressed in primary colon cancer, but not normal matched tissue, and confirmed expression in colon cancer-derived cell lines. We further characterized a TE-gene chimeric transcript involving the Interleukin 33 (IL-33) gene (termed LTR-IL-33), that is ectopically expressed in a subset of colon cancer samples through the use of an endogenous retroviral long terminal repeat (LTR) promoter of the MSTD family. The LTR-IL-33 chimeric transcript encodes a novel shorter isoform of the protein, which is missing the initial N-terminus (including many conserved residues) of Native IL-33. In vitro studies showed that LTR-IL-33 expression is required for optimal CRC cell line growth as 3D colonospheres. Taken together, these data demonstrate the significance of TEs as regulators of aberrant gene expression in colon cancer.
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Affiliation(s)
- Frances E. Lock
- Terry Fox Laboratory, British Columbia Cancer Agency, Vancouver, BC, Canada
- Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada
| | - Artem Babaian
- Terry Fox Laboratory, British Columbia Cancer Agency, Vancouver, BC, Canada
- Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada
| | - Ying Zhang
- Terry Fox Laboratory, British Columbia Cancer Agency, Vancouver, BC, Canada
- Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada
| | - Liane Gagnier
- Terry Fox Laboratory, British Columbia Cancer Agency, Vancouver, BC, Canada
- Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada
| | - Sabrina Kuah
- Terry Fox Laboratory, British Columbia Cancer Agency, Vancouver, BC, Canada
| | - Antonia Weberling
- Terry Fox Laboratory, British Columbia Cancer Agency, Vancouver, BC, Canada
| | - Mohammad M. Karimi
- Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada
- Département de Génomique Fonctionnelle et Cancer, Institut de Génétique et Biologie Moléculaire et Cellulaire (IGBMC)/Université de Strasbourg/CNRS/INSERM, France
| | - Dixie L. Mager
- Terry Fox Laboratory, British Columbia Cancer Agency, Vancouver, BC, Canada
- Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada
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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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32
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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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DNMT and HDAC inhibitors induce cryptic transcription start sites encoded in long terminal repeats. Nat Genet 2017; 49:1052-1060. [PMID: 28604729 DOI: 10.1038/ng.3889] [Citation(s) in RCA: 188] [Impact Index Per Article: 26.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2016] [Accepted: 05/03/2017] [Indexed: 12/13/2022]
Abstract
Several mechanisms of action have been proposed for DNA methyltransferase and histone deacetylase inhibitors (DNMTi and HDACi), primarily based on candidate-gene approaches. However, less is known about their genome-wide transcriptional and epigenomic consequences. By mapping global transcription start site (TSS) and chromatin dynamics, we observed the cryptic transcription of thousands of treatment-induced non-annotated TSSs (TINATs) following DNMTi and HDACi treatment. The resulting transcripts frequently splice into protein-coding exons and encode truncated or chimeric ORFs translated into products with predicted abnormal or immunogenic functions. TINAT transcription after DNMTi treatment coincided with DNA hypomethylation and gain of classical promoter histone marks, while HDACi specifically induced a subset of TINATs in association with H2AK9ac, H3K14ac, and H3K23ac. Despite this mechanistic difference, both inhibitors convergently induced transcription from identical sites, as we found TINATs to be encoded in solitary long terminal repeats of the ERV9/LTR12 family, which are epigenetically repressed in virtually all normal cells.
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Anwar SL, Wulaningsih W, Lehmann U. Transposable Elements in Human Cancer: Causes and Consequences of Deregulation. Int J Mol Sci 2017; 18:E974. [PMID: 28471386 PMCID: PMC5454887 DOI: 10.3390/ijms18050974] [Citation(s) in RCA: 84] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2017] [Revised: 04/26/2017] [Accepted: 04/29/2017] [Indexed: 01/04/2023] Open
Abstract
Transposable elements (TEs) comprise nearly half of the human genome and play an essential role in the maintenance of genomic stability, chromosomal architecture, and transcriptional regulation. TEs are repetitive sequences consisting of RNA transposons, DNA transposons, and endogenous retroviruses that can invade the human genome with a substantial contribution in human evolution and genomic diversity. TEs are therefore firmly regulated from early embryonic development and during the entire course of human life by epigenetic mechanisms, in particular DNA methylation and histone modifications. The deregulation of TEs has been reported in some developmental diseases, as well as for different types of human cancers. To date, the role of TEs, the mechanisms underlying TE reactivation, and the interplay with DNA methylation in human cancers remain largely unexplained. We reviewed the loss of epigenetic regulation and subsequent genomic instability, chromosomal aberrations, transcriptional deregulation, oncogenic activation, and aberrations of non-coding RNAs as the potential mechanisms underlying TE deregulation in human cancers.
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Affiliation(s)
- Sumadi Lukman Anwar
- Division of Surgical Oncology, Department of Surgery Faculty of Medicine, Universitas Gadjah Mada, Yogyakarta 55281, Indonesia.
- Institute of Pathology, Medizinische Hochschule Hannover, Hannover 30625, Germany.
- PILAR (Philippine and Indonesian Scholar) Research and Education, 20 Station Road, Cambridge CB1 2JD, UK.
| | - Wahyu Wulaningsih
- PILAR (Philippine and Indonesian Scholar) Research and Education, 20 Station Road, Cambridge CB1 2JD, UK.
- MRC (Medical Research Council) Unit for Lifelong Health and Ageing, University College London, London WC1B 5JU, UK.
- Division of Haematology/Oncology, Faculty of Medicine Universitas Gadjah Mada, Yogyakarta 55281, Indonesia.
| | - Ulrich Lehmann
- Institute of Pathology, Medizinische Hochschule Hannover, Hannover 30625, Germany.
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EnHERV: Enrichment analysis of specific human endogenous retrovirus patterns and their neighboring genes. PLoS One 2017; 12:e0177119. [PMID: 28472109 PMCID: PMC5417679 DOI: 10.1371/journal.pone.0177119] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2016] [Accepted: 04/21/2017] [Indexed: 12/24/2022] Open
Abstract
Human endogenous retroviruses (HERVs) are flanked by long terminal repeats (LTRs), which contain the regulation part of the retrovirus. Remaining HERVs constitute 7% to 8% of the present day human genome, and most have been identified as solo LTRs. The HERV sequences have been associated with several molecular functions as well as certain diseases in human, but their roles in human diseases are yet to be established. We designed EnHERV to make accessible the identified endogenous retrovirus repetitive sequences from Repbase Update (a database of eukaryotic repetitive elements) that are present in the human genome. Defragmentation process was done to improve the RepeatMasker annotation output. The defragmented elements were used as core database in EnHERV. EnHERV is available at http://sysbio.chula.ac.th/enherv and can be searched using either gene lists of user interest or HERV characteristics. Besides the search function, EnHERV also provides an enrichment analysis function that allows users to perform enrichment analysis between selected HERV characteristics and user-input gene lists, especially genes with the expression profile of a certain disease. EnHERV will facilitate exploratory studies of specific HERV characteristics that control gene expression patterns related to various disease conditions. Here we analyzed 25 selected HERV groups/names from all four HERV superfamilies, using the sense and anti-sense directions of the HERV and gene expression profiles from 49 specific tissue and disease conditions. We found that intragenic HERVs were associated with down-regulated genes in most cancer conditions and in psoriatic skin tissues and associated with up-regulated genes in immune cells particularly from systemic lupus erythematosus (SLE) patients. EnHERV allowed the analysis of how different types of LTRs were differentially associated with specific gene expression profiles in particular disease conditions for further studies into their mechanisms and functions.
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36
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Babaian A, Mager DL. Endogenous retroviral promoter exaptation in human cancer. Mob DNA 2016; 7:24. [PMID: 27980689 PMCID: PMC5134097 DOI: 10.1186/s13100-016-0080-x] [Citation(s) in RCA: 149] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Accepted: 11/11/2016] [Indexed: 12/13/2022] Open
Abstract
Cancer arises from a series of genetic and epigenetic changes, which result in abnormal expression or mutational activation of oncogenes, as well as suppression/inactivation of tumor suppressor genes. Aberrant expression of coding genes or long non-coding RNAs (lncRNAs) with oncogenic properties can be caused by translocations, gene amplifications, point mutations or other less characterized mechanisms. One such mechanism is the inappropriate usage of normally dormant, tissue-restricted or cryptic enhancers or promoters that serve to drive oncogenic gene expression. Dispersed across the human genome, endogenous retroviruses (ERVs) provide an enormous reservoir of autonomous gene regulatory modules, some of which have been co-opted by the host during evolution to play important roles in normal regulation of genes and gene networks. This review focuses on the “dark side” of such ERV regulatory capacity. Specifically, we discuss a growing number of examples of normally dormant or epigenetically repressed ERVs that have been harnessed to drive oncogenes in human cancer, a process we term onco-exaptation, and we propose potential mechanisms that may underlie this phenomenon.
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Affiliation(s)
- Artem Babaian
- Terry Fox Laboratory, British Columbia Cancer Agency, 675 West 10th Avenue, Vancouver, BC V5Z1L3 Canada ; Department of Medical Genetics, University of British Columbia, Vancouver, BC Canada
| | - Dixie L Mager
- Terry Fox Laboratory, British Columbia Cancer Agency, 675 West 10th Avenue, Vancouver, BC V5Z1L3 Canada ; Department of Medical Genetics, University of British Columbia, Vancouver, BC Canada
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37
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Ishak CA, Marshall AE, Passos DT, White CR, Kim SJ, Cecchini MJ, Ferwati S, MacDonald WA, Howlett CJ, Welch ID, Rubin SM, Mann MRW, Dick FA. An RB-EZH2 Complex Mediates Silencing of Repetitive DNA Sequences. Mol Cell 2016; 64:1074-1087. [PMID: 27889452 DOI: 10.1016/j.molcel.2016.10.021] [Citation(s) in RCA: 116] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Revised: 08/17/2016] [Accepted: 10/17/2016] [Indexed: 12/21/2022]
Abstract
Repetitive genomic regions include tandem sequence repeats and interspersed repeats, such as endogenous retroviruses and LINE-1 elements. Repressive heterochromatin domains silence expression of these sequences through mechanisms that remain poorly understood. Here, we present evidence that the retinoblastoma protein (pRB) utilizes a cell-cycle-independent interaction with E2F1 to recruit enhancer of zeste homolog 2 (EZH2) to diverse repeat sequences. These include simple repeats, satellites, LINEs, and endogenous retroviruses as well as transposon fragments. We generated a mutant mouse strain carrying an F832A mutation in Rb1 that is defective for recruitment to repetitive sequences. Loss of pRB-EZH2 complexes from repeats disperses H3K27me3 from these genomic locations and permits repeat expression. Consistent with maintenance of H3K27me3 at the Hox clusters, these mice are developmentally normal. However, susceptibility to lymphoma suggests that pRB-EZH2 recruitment to repetitive elements may be cancer relevant.
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Affiliation(s)
- Charles A Ishak
- London Regional Cancer Program, London, ON N6A 4L6, Canada; Department of Biochemistry, Western University, London, ON N6A 3K7, Canada
| | - Aren E Marshall
- London Regional Cancer Program, London, ON N6A 4L6, Canada; Department of Biochemistry, Western University, London, ON N6A 3K7, Canada
| | - Daniel T Passos
- London Regional Cancer Program, London, ON N6A 4L6, Canada; Department of Biochemistry, Western University, London, ON N6A 3K7, Canada
| | - Carlee R White
- Children's Health Research Institute, London, ON N6A 4L6, Canada; Department of Biochemistry, Western University, London, ON N6A 3K7, Canada
| | - Seung J Kim
- London Regional Cancer Program, London, ON N6A 4L6, Canada; Department of Biochemistry, Western University, London, ON N6A 3K7, Canada
| | - Matthew J Cecchini
- London Regional Cancer Program, London, ON N6A 4L6, Canada; Department of Pathology and Laboratory Medicine, Western University, London, ON N6A 3K7, Canada
| | - Sara Ferwati
- London Regional Cancer Program, London, ON N6A 4L6, Canada; Department of Biochemistry, Western University, London, ON N6A 3K7, Canada
| | - William A MacDonald
- Magee-Womens Research Institute, Pittsburgh, PA 15213, USA; Department of Obstetrics, Gynecology, and Reproductive Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Christopher J Howlett
- Department of Pathology and Laboratory Medicine, Western University, London, ON N6A 3K7, Canada
| | - Ian D Welch
- Animal Care Services, University of British Columbia, Vancouver, BC V6T1Z4, Canada
| | - Seth M Rubin
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, Santa Cruz, CA 95064, USA
| | - Mellissa R W Mann
- Magee-Womens Research Institute, Pittsburgh, PA 15213, USA; Department of Obstetrics, Gynecology, and Reproductive Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Frederick A Dick
- London Regional Cancer Program, London, ON N6A 4L6, Canada; Children's Health Research Institute, London, ON N6A 4L6, Canada; Department of Biochemistry, Western University, London, ON N6A 3K7, Canada.
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Chuong EB, Elde NC, Feschotte C. Regulatory activities of transposable elements: from conflicts to benefits. Nat Rev Genet 2016; 18:71-86. [PMID: 27867194 DOI: 10.1038/nrg.2016.139] [Citation(s) in RCA: 777] [Impact Index Per Article: 97.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Transposable elements (TEs) are a prolific source of tightly regulated, biochemically active non-coding elements, such as transcription factor-binding sites and non-coding RNAs. Many recent studies reinvigorate the idea that these elements are pervasively co-opted for the regulation of host genes. We argue that the inherent genetic properties of TEs and the conflicting relationships with their hosts facilitate their recruitment for regulatory functions in diverse genomes. We review recent findings supporting the long-standing hypothesis that the waves of TE invasions endured by organisms for eons have catalysed the evolution of gene-regulatory networks. We also discuss the challenges of dissecting and interpreting the phenotypic effect of regulatory activities encoded by TEs in health and disease.
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Affiliation(s)
- Edward B Chuong
- Department of Human Genetics, University of Utah School of Medicine, Salt Lake City, Utah 84103, USA
| | - Nels C Elde
- Department of Human Genetics, University of Utah School of Medicine, Salt Lake City, Utah 84103, USA
| | - Cédric Feschotte
- Department of Human Genetics, University of Utah School of Medicine, Salt Lake City, Utah 84103, USA
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Kassiotis G, Stoye JP. Immune responses to endogenous retroelements: taking the bad with the good. Nat Rev Immunol 2016; 16:207-19. [PMID: 27026073 DOI: 10.1038/nri.2016.27] [Citation(s) in RCA: 165] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The ultimate form of parasitism and evasion of host immunity is for the parasite genome to enter the germ line of the host species. Retroviruses have invaded the host germ line on the grandest scale, and this is evident in the extraordinary abundance of endogenous retroelements in the genome of all vertebrate species that have been studied. Many of these endogenous retroelements have retained viral characteristics; some also the capacity to replicate and, consequently, the potential to trigger host innate and adaptive immune responses. However, although retroelements are mainly recognized for their pathogenic potential, recent evidence suggests that this 'enemy within' may also have beneficial roles in tuning host immune reactivity. In this Review, we discuss how the immune system recognizes and is shaped by endogenous retroelements.
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Affiliation(s)
- George Kassiotis
- Retroviral Immunology, the Francis Crick Institute, Mill Hill Laboratory, London NW7 1AA, UK.,Department of Medicine, Faculty of Medicine, Imperial College London, London W2 1PG, UK
| | - Jonathan P Stoye
- Department of Medicine, Faculty of Medicine, Imperial College London, London W2 1PG, UK.,Retrovirus-Host Interactions, the Francis Crick Institute, Mill Hill Laboratory, London NW7 1AA, UK
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A Novel Analytical Strategy to Identify Fusion Transcripts between Repetitive Elements and Protein Coding-Exons Using RNA-Seq. PLoS One 2016; 11:e0159028. [PMID: 27415830 PMCID: PMC4945064 DOI: 10.1371/journal.pone.0159028] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2016] [Accepted: 06/24/2016] [Indexed: 12/27/2022] Open
Abstract
Repetitive elements (REs) comprise 40-60% of the mammalian genome and have been shown to epigenetically influence the expression of genes through the formation of fusion transcript (FTs). We previously showed that an intracisternal A particle forms an FT with the agouti gene in mice, causing obesity/type 2 diabetes. To determine the frequency of FTs genome-wide, we developed a TopHat-Fusion-based analytical pipeline to identify FTs with high specificity. We applied it to an RNA-seq dataset from the nucleus accumbens (NAc) of mice repeatedly exposed to cocaine. Cocaine was previously shown to increase the expression of certain REs in this brain region. Using this pipeline that can be applied to single- or paired-end reads, we identified 438 genes expressing 813 different FTs in the NAc. Although all types of studied repeats were present in FTs, simple sequence repeats were underrepresented. Most importantly, reverse-transcription and quantitative PCR validated the expression of selected FTs in an independent cohort of animals, which also revealed that some FTs are the prominent isoforms expressed in the NAc by some genes. In other RNA-seq datasets, developmental expression as well as tissue specificity of some FTs differed from their corresponding non-fusion counterparts. Finally, in silico analysis predicted changes in the structure of proteins encoded by some FTs, potentially resulting in gain or loss of function. Collectively, these results indicate the robustness of our pipeline in detecting these new isoforms of genes, which we believe provides a valuable tool to aid in better understanding the broad role of REs in mammalian cellular biology.
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Göke J, Ng HH. CTRL+INSERT: retrotransposons and their contribution to regulation and innovation of the transcriptome. EMBO Rep 2016; 17:1131-44. [PMID: 27402545 DOI: 10.15252/embr.201642743] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Accepted: 06/20/2016] [Indexed: 12/25/2022] Open
Abstract
The human genome contains millions of fragments from retrotransposons-highly repetitive DNA sequences that were once able to "copy and paste" themselves to other regions in the genome. However, the majority of retrotransposons have lost this capacity through acquisition of mutations or through endogenous silencing mechanisms. Without this imminent threat of transposition, retrotransposons have the potential to act as a major source of genomic innovation. Indeed, large numbers of retrotransposons have been found to be active in specific contexts: as gene regulatory elements and promoters for protein-coding genes or long noncoding RNAs, among others. In this review, we summarise recent findings about retrotransposons, with implications in gene expression regulation, the expansion of gene isoform diversity and the generation of long noncoding RNAs. We highlight key examples that demonstrate their role in cellular identity and their versatility as markers of cell states, and we discuss how their dysregulation may contribute to the formation of and possibly therapeutic response in human cancers.
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Affiliation(s)
- Jonathan Göke
- Computational and Systems Biology, Genome Institute of Singapore, Singapore
| | - Huck Hui Ng
- Gene Regulation Laboratory, Genome Institute of Singapore, Singapore Department of Biochemistry, National University of Singapore, Singapore Department of Biological Sciences, National University of Singapore, Singapore School of Biological Sciences, Nanyang Technological University, Singapore
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Scarfò I, Pellegrino E, Mereu E, Inghirami G, Piva R. Transposable elements: The enemies within. Exp Hematol 2016; 44:913-6. [PMID: 27377925 DOI: 10.1016/j.exphem.2016.06.251] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Revised: 06/21/2016] [Accepted: 06/22/2016] [Indexed: 12/28/2022]
Abstract
Understanding transformation mechanisms other than genetic aberrations has recently captured the attention of cancer researchers. To date, the role of transposable elements (TEs) in tumor development remains largely undefined. However, an increasing number of studies have reported that loss of epigenetic control causes TE reactivation and consequent oncogenic transcription. Here, we discuss principal examples of TEs-driven oncogenesis. Available data suggest that long terminal repeats and long interspersed nuclear elements play a pivotal role as alternative promoters. These findings provide definitive experimental evidence that repetitive elements are a powerful underestimated force toward oncogenesis and open the possibility to new therapeutic treatments.
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Affiliation(s)
- Irene Scarfò
- Department of Molecular Biotechnology and Health Sciences; Center for Experimental Research and Medical Studies, University of Torino, Torino, Italy
| | - Elisa Pellegrino
- Department of Molecular Biotechnology and Health Sciences; Center for Experimental Research and Medical Studies, University of Torino, Torino, Italy
| | - Elisabetta Mereu
- Department of Molecular Biotechnology and Health Sciences; Center for Experimental Research and Medical Studies, University of Torino, Torino, Italy
| | - Giorgio Inghirami
- Department of Molecular Biotechnology and Health Sciences; Center for Experimental Research and Medical Studies, University of Torino, Torino, Italy; Department of Pathology and Laboratory Medicine, Weill Cornell Medical College, New York, NY, USA
| | - Roberto Piva
- Department of Molecular Biotechnology and Health Sciences; Center for Experimental Research and Medical Studies, University of Torino, Torino, Italy.
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43
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Weiss RA. Human endogenous retroviruses: friend or foe? APMIS 2016; 124:4-10. [PMID: 26818257 DOI: 10.1111/apm.12476] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Accepted: 10/12/2015] [Indexed: 01/21/2023]
Abstract
The integration of proviral DNA into host chromosomal DNA as an obligatory step in the replication cycle of retroviruses is a natural event of genetic recombination between virus and host. When integration occurs in cells of the germ line, it results in mendelian inheritance of viral sequences that we call endogenous retroviruses (ERV) and HERV for humans. HERVs and host often establish a symbiotic relationship, especially in the placenta and in pluripotent embryonic stem cells, but HERVs occasionally have deleterious consequences for the host. This special issue of APMIS features the fascinating relationships between HERV and humans in health and disease.
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Affiliation(s)
- Robin A Weiss
- Division of Infection & Immunity, University College London, London, UK
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44
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Sokol M, Jessen KM, Pedersen FS. Utility of next-generation RNA-sequencing in identifying chimeric transcription involving human endogenous retroviruses. APMIS 2016; 124:127-39. [PMID: 26818267 DOI: 10.1111/apm.12477] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Accepted: 10/12/2015] [Indexed: 12/13/2022]
Abstract
Several studies have shown that human endogenous retroviruses and endogenous retrovirus-like repeats (here collectively HERVs) impose direct regulation on human genes through enhancer and promoter motifs present in their long terminal repeats (LTRs). Although chimeric transcription in which novel gene isoforms containing retroviral and human sequence are transcribed from viral promoters are commonly associated with disease, regulation by HERVs is beneficial in other settings; for example, in human testis chimeric isoforms of TP63 induced by an ERV9 LTR protect the male germ line upon DNA damage by inducing apoptosis, whereas in the human globin locus the γ- and β-globin switch during normal hematopoiesis is mediated by complex interactions of an ERV9 LTR and surrounding human sequence. The advent of deep sequencing or next-generation sequencing (NGS) has revolutionized the way researchers solve important scientific questions and develop novel hypotheses in relation to human genome regulation. We recently applied next-generation paired-end RNA-sequencing (RNA-seq) together with chromatin immunoprecipitation with sequencing (ChIP-seq) to examine ERV9 chimeric transcription in human reference cell lines from Encyclopedia of DNA Elements (ENCODE). This led to the discovery of advanced regulation mechanisms by ERV9s and other HERVs across numerous human loci including transcription of large gene-unannotated genomic regions, as well as cooperative regulation by multiple HERVs and non-LTR repeats such as Alu elements. In this article, well-established examples of human gene regulation by HERVs are reviewed followed by a description of paired-end RNA-seq, and its application in identifying chimeric transcription genome-widely. Based on integrative analyses of RNA-seq and ChIP-seq, data we then present novel examples of regulation by ERV9s of tumor suppressor genes CADM2 and SEMA3A, as well as transcription of an unannotated region. Taken together, this article highlights the high suitability of contemporary sequencing methods in future analyses of human biology in relation to evolutionary acquired retroviruses in the human genome.
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Affiliation(s)
- Martin Sokol
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
| | | | - Finn Skou Pedersen
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
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Babaian A, Romanish MT, Gagnier L, Kuo LY, Karimi MM, Steidl C, Mager DL. Onco-exaptation of an endogenous retroviral LTR drives IRF5 expression in Hodgkin lymphoma. Oncogene 2015; 35:2542-6. [DOI: 10.1038/onc.2015.308] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2015] [Revised: 05/21/2015] [Accepted: 07/13/2015] [Indexed: 12/11/2022]
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Sokol M, Jessen KM, Pedersen FS. Human endogenous retroviruses sustain complex and cooperative regulation of gene-containing loci and unannotated megabase-sized regions. Retrovirology 2015; 12:32. [PMID: 25927889 PMCID: PMC4422309 DOI: 10.1186/s12977-015-0161-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2015] [Accepted: 03/30/2015] [Indexed: 12/19/2022] Open
Abstract
Background Evidence suggests that some human endogenous retroviruses and endogenous retrovirus-like repeats (here collectively ERVs) regulate the expression of neighboring genes in normal and disease states; e.g. the human globin locus is regulated by an ERV9 that coordinates long-range gene switching during hematopoiesis and activates also intergenic transcripts. While complex transcription regulation is associated with integration of certain exogenous retroviruses, comparable regulation sustained by ERVs is less understood. Findings We analyzed ERV transcription using ERV9 consensus sequences and publically available RNA-sequencing, chromatin immunoprecipitation with sequencing (ChIP-seq) and cap analysis gene expression (CAGE) data from ENCODE. We discovered previously undescribed and advanced transcription regulation mechanisms in several human reference cell lines. We show that regulation by ERVs involves long-ranging activations including complex RNA splicing patterns, and transcription of large unannotated regions ranging in size from several hundred kb to around 1 Mb. Moreover, regulation was found to be cooperatively sustained in some loci by multiple ERVs and also non-LTR repeats. Conclusion Our analyses show that endogenous retroviruses sustain advanced transcription regulation in human cell lines, which shows similarities to complex insertional mutagenesis effects exerted by exogenous retroviruses. By exposing previously undescribed regulation effects, this study should prove useful for understanding fundamental transcription mechanisms resulting from evolutionary acquisition of retroviral sequence in the human genome. Electronic supplementary material The online version of this article (doi:10.1186/s12977-015-0161-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Martin Sokol
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, DK-8000, Denmark.
| | - Karen Margrethe Jessen
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, DK-8000, Denmark.
| | - Finn Skou Pedersen
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, DK-8000, Denmark.
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Human endogenous retrovirus group E and its involvement in diseases. Viruses 2015; 7:1238-57. [PMID: 25785516 PMCID: PMC4379568 DOI: 10.3390/v7031238] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Revised: 02/12/2015] [Accepted: 02/23/2015] [Indexed: 02/07/2023] Open
Abstract
Human endogenous retrovirus group E (HERV-E) elements are stably integrated into the human genome, transmitted vertically in a Mendelian manner, and are endowed with transcriptional activity as alternative promoters or enhancers. Such effects are under the control of the proviral long terminal repeats (LTR) that are organized into three HERV-E phylogenetic subgroups, namely LTR2, LTR2B, and LTR2C. Moreover, HERV-E expression is tissue-specific, and silenced by epigenetic constraints that may be disrupted in cancer, autoimmunity, and human placentation. Interest in HERV-E with regard to these conditions has been stimulated further by concerns regarding the capacity of HERV-E elements to modify the expression of neighboring genes and/or to produce retroviral proteins, including immunosuppressive env peptides, which in turn may induce (auto)-antibody (Ab) production. Finally, better understanding of HERV-E elements may have clinical applications for prevention, diagnosis, prognosis, and therapy.
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48
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Pavlicev M, Hiratsuka K, Swaggart KA, Dunn C, Muglia L. Detecting endogenous retrovirus-driven tissue-specific gene transcription. Genome Biol Evol 2015; 7:1082-97. [PMID: 25767249 PMCID: PMC4419796 DOI: 10.1093/gbe/evv049] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Transposable elements (TEs) comprise approximately half of the human genome, and several independent lines of investigation have demonstrated their role in rewiring gene expression during development, evolution, and oncogenesis. The identification of their regulatory effects has largely been idiosyncratic, by linking activity with isolated genes. Their distribution throughout the genome raises critical questions—do these elements contribute to broad tissue- and lineage-specific regulation? If so, in what manner, as enhancers, promoters, RNAs? Here, we devise a novel approach to systematically dissect the genome-wide consequences of TE insertion on gene expression, and test the hypothesis that classes of endogenous retrovirus long terminal repeats (LTRs) exert tissue-specific regulation of adjacent genes. Using correlation of expression patterns across 18 tissue types, we reveal the tissue-specific uncoupling of gene expression due to 62 different LTR classes. These patterns are specific to the retroviral insertion, as the same genes in species without the LTRs do not exhibit the same effect. Although the LTRs can be transcribed themselves, the most highly transcribed TEs do not have the largest effects on adjacent regulation of coding genes, suggesting they function predominantly as enhancers. Moreover, the tissue-specific patterns of gene expression that are detected by our method arise from a limited number of genes, rather than as a general consequence of LTR integration. These findings identify basic principles of co-opting LTRs for genome evolution, and support the utility of our method for the analysis of TE, or other specific gene sets, in relation to the rest of the genome.
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Affiliation(s)
- Mihaela Pavlicev
- Center for Prevention of Preterm Birth, Perinatal Institute, Cincinnati Children's Hospital Medical Center and Department of Pediatrics, University of Cincinnati College of Medicine
| | - Kaori Hiratsuka
- Center for Prevention of Preterm Birth, Perinatal Institute, Cincinnati Children's Hospital Medical Center and Department of Pediatrics, University of Cincinnati College of Medicine
| | - Kayleigh A Swaggart
- Center for Prevention of Preterm Birth, Perinatal Institute, Cincinnati Children's Hospital Medical Center and Department of Pediatrics, University of Cincinnati College of Medicine
| | - Caitlin Dunn
- Center for Prevention of Preterm Birth, Perinatal Institute, Cincinnati Children's Hospital Medical Center and Department of Pediatrics, University of Cincinnati College of Medicine
| | - Louis Muglia
- Center for Prevention of Preterm Birth, Perinatal Institute, Cincinnati Children's Hospital Medical Center and Department of Pediatrics, University of Cincinnati College of Medicine
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Gibb EA, Warren RL, Wilson GW, Brown SD, Robertson GA, Morin GB, Holt RA. Activation of an endogenous retrovirus-associated long non-coding RNA in human adenocarcinoma. Genome Med 2015; 7:22. [PMID: 25821520 PMCID: PMC4375928 DOI: 10.1186/s13073-015-0142-6] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Accepted: 02/12/2015] [Indexed: 11/15/2022] Open
Abstract
Background Long non-coding RNAs (lncRNAs) are emerging as molecules that significantly impact many cellular processes and have been associated with almost every human cancer. Compared to protein-coding genes, lncRNA genes are often associated with transposable elements, particularly with endogenous retroviral elements (ERVs). ERVs can have potentially deleterious effects on genome structure and function, so these elements are typically silenced in normal somatic tissues, albeit with varying efficiency. The aberrant regulation of ERVs associated with lncRNAs (ERV-lncRNAs), coupled with the diverse range of lncRNA functions, creates significant potential for ERV-lncRNAs to impact cancer biology. Methods We used RNA-seq analysis to identify and profile the expression of a novel lncRNA in six large cohorts, including over 7,500 samples from The Cancer Genome Atlas (TCGA). Results We identified the tumor-specific expression of a novel lncRNA that we have named Endogenous retroViral-associated ADenocarcinoma RNA or ‘EVADR’, by analyzing RNA-seq data derived from colorectal tumors and matched normal control tissues. Subsequent analysis of TCGA RNA-seq data revealed the striking association of EVADR with adenocarcinomas, which are tumors of glandular origin. Moderate to high levels of EVADR were detected in 25 to 53% of colon, rectal, lung, pancreas and stomach adenocarcinomas (mean = 30 to 144 FPKM), and EVADR expression correlated with decreased patient survival (Cox regression; hazard ratio = 1.47, 95% confidence interval = 1.06 to 2.04, P = 0.02). In tumor sites of non-glandular origin, EVADR expression was detectable at only very low levels and in less than 10% of patients. For EVADR, a MER48 ERV element provides an active promoter to drive its transcription. Genome-wide, MER48 insertions are associated with nine lncRNAs, but none of the MER48-associated lncRNAs other than EVADR were consistently expressed in adenocarcinomas, demonstrating the specific activation of EVADR. The sequence and structure of the EVADR locus is highly conserved among Old World monkeys and apes but not New World monkeys or prosimians, where the MER48 insertion is absent. Conservation of the EVADR locus suggests a functional role for this novel lncRNA in humans and our closest primate relatives. Conclusions Our results describe the specific activation of a highly conserved ERV-lncRNA in numerous cancers of glandular origin, a finding with diagnostic, prognostic and therapeutic implications. Electronic supplementary material The online version of this article (doi:10.1186/s13073-015-0142-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Ewan A Gibb
- Genome Sciences Centre, British Columbia Cancer Agency, 675 West 10th Ave, Vancouver, British Columbia V5Z 1L3 Canada ; Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia V6T 1Z4 Canada
| | - René L Warren
- Genome Sciences Centre, British Columbia Cancer Agency, 675 West 10th Ave, Vancouver, British Columbia V5Z 1L3 Canada
| | - Gavin W Wilson
- Informatics and Biocomputing Platform, Ontario Institute for Cancer Research, Toronto, Ontario M5G 0A3 Canada ; Department of Molecular Genetics, University of Toronto, Toronto, Ontario M5S 1A8 Canada
| | - Scott D Brown
- Genome Sciences Centre, British Columbia Cancer Agency, 675 West 10th Ave, Vancouver, British Columbia V5Z 1L3 Canada ; Genome Science and Technology Program, University of British Columbia, Vancouver, British Columbia V6T 1Z4 Canada
| | - Gordon A Robertson
- Genome Sciences Centre, British Columbia Cancer Agency, 675 West 10th Ave, Vancouver, British Columbia V5Z 1L3 Canada
| | - Gregg B Morin
- Genome Sciences Centre, British Columbia Cancer Agency, 675 West 10th Ave, Vancouver, British Columbia V5Z 1L3 Canada ; Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia V6T 1Z4 Canada ; Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia V5A 1S6 Canada
| | - Robert A Holt
- Genome Sciences Centre, British Columbia Cancer Agency, 675 West 10th Ave, Vancouver, British Columbia V5Z 1L3 Canada ; Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia V6T 1Z4 Canada ; Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia V5A 1S6 Canada
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