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Kyriakou E, Magiorkinis G. Interplay between endogenous and exogenous human retroviruses. Trends Microbiol 2023; 31:933-946. [PMID: 37019721 DOI: 10.1016/j.tim.2023.03.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Revised: 03/09/2023] [Accepted: 03/13/2023] [Indexed: 04/07/2023]
Abstract
In humans, retroviruses thrive more as symbionts than as parasites. Apart from the only two modern exogenous human retroviruses (human T-cell lymphotropic and immunodeficiency viruses; HTLV and HIV, respectively), ~8% of the human genome is occupied by ancient retroviral DNA [human endogenous retroviruses (HERVs)]. Here, we review the recent discoveries about the interactions between the two groups, the impact of infection by exogenous retroviruses on the expression of HERVs, the effect of HERVs on the pathogenicity of HIV and HTLV and on the severity of the diseases caused by them, and the antiviral protection that HERVs can allegedly provide to the host. Tracing the crosstalk between contemporary retroviruses and their endogenized ancestors will provide better understanding of the retroviral world.
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Affiliation(s)
- Eleni Kyriakou
- Department of Hygiene, Epidemiology and Medical Statistics, School of Medicine, National and Kapodistrian University of Athens, Athens, Greece
| | - Gkikas Magiorkinis
- Department of Hygiene, Epidemiology and Medical Statistics, School of Medicine, National and Kapodistrian University of Athens, Athens, Greece.
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2
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Jin X, Li X, Guan F, Zhang J. Human Endogenous Retroviruses and Toll-Like Receptors. Viral Immunol 2023; 36:73-82. [PMID: 36251943 DOI: 10.1089/vim.2022.0090] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Human endogenous retroviruses (HERVs) are estimated to comprise ∼8% of the entire human genome, but the vast majority of them remain transcriptionally silent in most normal tissues due to accumulated mutations. However, HERVs can be frequently activated and detected in various tissues under certain conditions. Nucleic acids or proteins produced by HERVs can bind to pattern recognition receptors of immune cells or other cells and initiate an innate immune response, which may be involved in some pathogenesis of diseases, especially cancer and autoimmune diseases. In this review, we collect studies of the interaction between HERV elements and Toll-like receptors and attempt to provide an overview of their role in the immunopathological mechanisms of inflammatory and autoimmune diseases.
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Affiliation(s)
- Xinyi Jin
- Department of Laboratory Medicine, School of Medicine, Shaoxing University, Shaoxing, P.R. China
| | - Xueyuan Li
- Department of Laboratory Medicine, School of Medicine, Shaoxing University, Shaoxing, P.R. China
| | - Fang Guan
- Department of Laboratory Medicine, School of Medicine, Shaoxing University, Shaoxing, P.R. China
| | - Jianhua Zhang
- Department of Laboratory Medicine, School of Medicine, Shaoxing University, Shaoxing, P.R. China
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Genome-Wide Characterization of Zebrafish Endogenous Retroviruses Reveals Unexpected Diversity in Genetic Organizations and Functional Potentials. Microbiol Spectr 2021; 9:e0225421. [PMID: 34908463 PMCID: PMC8672886 DOI: 10.1128/spectrum.02254-21] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Endogenous retroviruses (ERVs) occupy a substantial fraction of mammalian genomes. However, whether ERVs extensively exist in ancient vertebrates remains unexplored. Here, we performed a genome-wide characterization of ERVs in a zebrafish (Danio rerio) model. Approximately 3,315 ERV-like elements (DrERVs) were identified as Gypsy, Copia, Bel, and class I−III groups. DrERVs accounted for approximately 2.3% of zebrafish genome and were distributed in all 25 chromosomes, with a remarkable bias on chromosome 4. Gypsy and class I are the two most abundant groups with earlier insertion times. The vast majority of the DrERVs have varied structural defects. A total of 509 gag and 71 env genes with coding potentials were detected. The env-coding elements were well-characterized and classified into four subgroups. A ERV-E4.8.43-DanRer element shows high similarity with HERV9NC-int in humans and analogous sequences were detected in species spanning from fish to mammals. RNA-seq data showed that hundreds of DrERVs were expressed in embryos and tissues under physiological conditions, and most of them exhibited stage and tissue specificity. Additionally, 421 DrERVs showed strong responsiveness to virus infection. A unique group of DrERVs with immune-relevant genes, such as fga, ddx41, ftr35, igl1c3, and tbk1, instead of intrinsic viral genes were identified. These DrERVs are regulated by transcriptional factors binding at the long terminal repeats. This study provided a survey of the composition, phylogeny, and potential functions of ERVs in a fish model, which benefits the understanding of the evolutionary history of ERVs from fish to mammals. IMPORTANCE Endogenous retroviruses (ERVs) are relics of past infection that constitute up to 8% of the human genome. Understanding the genetic evolution of the ERV family and the interplay of ERVs and encoded RNAs and proteins with host function has become a new frontier in biology. Fish, as the most primitive vertebrate host for retroviruses, is an indispensable integral part for such investigations. In the present study, we report the genome-wide characterization of ERVs in zebrafish, an attractive model organism of ancient vertebrates from multiple perspectives, including composition, genomic organization, chromosome distribution, classification, phylogeny, insertion time, characterization of gag and env genes, and expression profiles in embryos and tissues. The result helps uncover the evolutionarily conserved and fish-specific ERVs, as well as the immune-relevant ERVs in response to virus infection. This study demonstrates the previously unrecognized abundance, diversification, and extensive activity of ERVs at the early stage of ERV evolution.
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4
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Transcription of Endogenous Retrovirus Group K Members and Their Neighboring Genes in Chicken Skeletal Muscle Myoblasts. J Poult Sci 2021; 58:79-87. [PMID: 33927561 PMCID: PMC8076618 DOI: 10.2141/jpsa.0200021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Skeletal muscle myoblasts are myogenic precursor cells that generate myofibers during muscle development and growth. We recently reported that broiler myoblasts, compared to layer myoblasts, proliferate and differentiate more actively and promptly into myocytes, which corresponds well with the muscle phenotype of broilers. Furthermore, RNA sequencing (RNA-seq) revealed that numerous genes are differentially expressed between layer and broiler myoblasts during myogenic differentiation. Based on the RNA-seq data, we herein report that chicken myoblasts transcribe endogenous retrovirus group K member (ERVK) genes. In total, 16 ERVKs were highly expressed in layer myoblasts and two (termed BrK1 and BrK2) were significantly induced in broiler myoblasts. These transcribed ERVKs had a total of 182 neighboring genes within ±100 kb on the chromosomes, of which 40% were concentrated within ±10 kb of the ERVKs. We further investigated whether the transcription of ERVKs affects the expression of their neighboring genes. BrK1 had two neighboring genes; LOC107052719 was overlapping with BrK1 and downregulated in the broiler myoblasts, and FAM19A2 was upregulated in the broiler myoblasts as well as BrK1. BrK2 had 14 neighboring genes, and only one gene, LOC772243, was differentially expressed between layer and broiler myoblasts. LOC772243 was overlapping with BrK2 and suppressed in the broiler myoblasts. These data indicate that the transcription of ERVKs may impact the expression of their neighboring genes in chicken myoblasts.
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Xue B, Sechi LA, Kelvin DJ. Human Endogenous Retrovirus K (HML-2) in Health and Disease. Front Microbiol 2020; 11:1690. [PMID: 32765477 PMCID: PMC7380069 DOI: 10.3389/fmicb.2020.01690] [Citation(s) in RCA: 59] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Accepted: 06/29/2020] [Indexed: 02/05/2023] Open
Abstract
Human endogenous retroviruses (HERVs) are derived from exogenous retrovirus infections in the evolution of primates and account for about 8% of the human genome. They were considered as silent passengers within our genomes for a long time, however, reactivation of HERVs has been associated with tumors and autoimmune diseases, especially the HERV-K (HML-2) family, the most recent integration groups with the least number of mutations and the most biologically active to encode functional retroviral proteins and produce retrovirus-like particles. Increasing studies are committed to determining the potential role of HERV-K (HML-2) in pathogenicity. Although there is still no evidence for HERV-K (HML-2) as a direct cause of diseases, aberrant expression profiles of the HERV-K (HML-2) transcripts and their regulatory function to their proximal host-genes were identified in different diseases. In this review, we summarized the advances between HERV-K (HML-2) and diseases to provide basis for further studies on the causal relationship between HERV-K (HML-2) and diseases. We recommended more attention to polymorphic integrated HERV-K (HML-2) loci which could be genetic causative factors and be associated with inter-individual differences in tumorigenesis and autoimmune diseases.
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Affiliation(s)
- Bei Xue
- Division of Immunology, Shantou University Medical College, Shantou, China
- Department of Microbiology and Immunology, Canadian Center for Vaccinology, Dalhousie University, Halifax, NS, Canada
| | - Leonardo A. Sechi
- Department of Biomedical Sciences, University of Sassari, Sassari, Italy
- Mediterranean Center for Disease Control, University of Sassari, Sassari, Italy
| | - David J. Kelvin
- Division of Immunology, Shantou University Medical College, Shantou, China
- Department of Microbiology and Immunology, Canadian Center for Vaccinology, Dalhousie University, Halifax, NS, Canada
- Department of Biomedical Sciences, University of Sassari, Sassari, Italy
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Xue B, Zeng T, Jia L, Yang D, Lin SL, Sechi LA, Kelvin DJ. Identification of the distribution of human endogenous retroviruses K (HML-2) by PCR-based target enrichment sequencing. Retrovirology 2020; 17:10. [PMID: 32375827 PMCID: PMC7201656 DOI: 10.1186/s12977-020-00519-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Accepted: 04/23/2020] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND Human endogenous retroviruses (HERVs), suspected to be transposition-defective, may reshape the transcriptional network of the human genome by regulatory elements distributed in their long terminal repeats (LTRs). HERV-K (HML-2), the most preserved group with the least number of accumulated of mutations, has been associated with aberrant gene expression in tumorigenesis and autoimmune diseases. Because of the high sequence similarity between different HERV-Ks, current methods have limitations in providing genome-wide mapping specific for individual HERV-K (HML-2) members, a major barrier in delineating HERV-K (HML-2) function. RESULTS In an attempt to obtain detailed distribution information of HERV-K (HML-2), we utilized a PCR-based target enrichment sequencing protocol for HERV-K (HML-2) (PTESHK) loci, which not only maps the presence of reference loci, but also identifies non-reference loci, enabling determination of the genome-wide distribution of HERV-K (HML-2) loci. Here we report on the genomic data obtained from three individuals. We identified a total of 978 loci using this method, including 30 new reference loci and 5 non-reference loci. Among the 3 individuals in our study, 14 polymorphic HERV-K (HML-2) loci were identified, and solo-LTR330 and N6p21.32 were identified as polymorphic for the first time. CONCLUSIONS Interestingly, PTESHK provides an approach for the identification of the genome-wide distribution of HERV-K (HML-2) and can be used for the identification of polymorphic loci. Since polymorphic HERV-K (HML-2) integrations are suspected to be related to various diseases, PTESHK can supplement other emerging techniques in accessing polymorphic HERV-K (HML-2) elements in cancer and autoimmune diseases.
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Affiliation(s)
- Bei Xue
- Division of Immunology, Shantou University Medical College, Shantou, China
- The Department of Microbiology and Immunology, Dalhousie University, Halifax, Canada
- Canadian Center for Vaccinology, Dalhousie University, Halifax, Canada
| | - Tiansheng Zeng
- Division of Immunology, Shantou University Medical College, Shantou, China
- Department of Biomedical Sciences, University of Sassari, Sassari, Italy
| | - Lisha Jia
- Division of Immunology, Shantou University Medical College, Shantou, China
| | - Dongsheng Yang
- Division of Immunology, Shantou University Medical College, Shantou, China
| | - Stanley L Lin
- Division of Immunology, Shantou University Medical College, Shantou, China
| | - Leonardo A Sechi
- Department of Biomedical Sciences, University of Sassari, Sassari, Italy.
| | - David J Kelvin
- Division of Immunology, Shantou University Medical College, Shantou, China.
- The Department of Microbiology and Immunology, Dalhousie University, Halifax, Canada.
- Canadian Center for Vaccinology, Dalhousie University, Halifax, Canada.
- Department of Biomedical Sciences, University of Sassari, Sassari, Italy.
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Dembny P, Newman AG, Singh M, Hinz M, Szczepek M, Krüger C, Adalbert R, Dzaye O, Trimbuch T, Wallach T, Kleinau G, Derkow K, Richard BC, Schipke C, Scheidereit C, Stachelscheid H, Golenbock D, Peters O, Coleman M, Heppner FL, Scheerer P, Tarabykin V, Ruprecht K, Izsvák Z, Mayer J, Lehnardt S. Human endogenous retrovirus HERV-K(HML-2) RNA causes neurodegeneration through Toll-like receptors. JCI Insight 2020; 5:131093. [PMID: 32271161 DOI: 10.1172/jci.insight.131093] [Citation(s) in RCA: 65] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Accepted: 03/04/2020] [Indexed: 01/27/2023] Open
Abstract
Although human endogenous retroviruses (HERVs) represent a substantial proportion of the human genome and some HERVs, such as HERV-K(HML-2), are reported to be involved in neurological disorders, little is known about their biological function. We report that RNA from an HERV-K(HML-2) envelope gene region binds to and activates human Toll-like receptor (TLR) 8, as well as murine Tlr7, expressed in neurons and microglia, thereby causing neurodegeneration. HERV-K(HML-2) RNA introduced into the cerebrospinal fluid (CSF) of either C57BL/6 wild-type mice or APPPS1 mice, a mouse model for Alzheimer's disease (AD), resulted in neurodegeneration and microglia accumulation. Tlr7-deficient mice were protected against neurodegenerative effects but were resensitized toward HERV-K(HML-2) RNA when neurons ectopically expressed murine Tlr7 or human TLR8. Transcriptome data sets of human AD brain samples revealed a distinct correlation of upregulated HERV-K(HML-2) and TLR8 RNA expression. HERV-K(HML-2) RNA was detectable more frequently in CSF from individuals with AD compared with controls. Our data establish HERV-K(HML-2) RNA as an endogenous ligand for species-specific TLRs 7/8 and imply a functional contribution of human endogenous retroviral transcripts to neurodegenerative processes, such as AD.
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Affiliation(s)
- Paul Dembny
- Institute of Cell Biology and Neurobiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health (BIH), Berlin, Germany
| | - Andrew G Newman
- Institute of Cell Biology and Neurobiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health (BIH), Berlin, Germany
| | - Manvendra Singh
- Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany
| | - Michael Hinz
- Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany
| | - Michal Szczepek
- Institute for Medical Physics and Biophysics, Group Protein X-ray Crystallography and Signal Transduction, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and BIH, Berlin, Germany
| | - Christina Krüger
- Institute of Cell Biology and Neurobiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health (BIH), Berlin, Germany
| | | | - Omar Dzaye
- Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany.,Department of Radiology.,Department of Neuroradiology
| | | | - Thomas Wallach
- Institute of Cell Biology and Neurobiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health (BIH), Berlin, Germany
| | - Gunnar Kleinau
- Institute for Medical Physics and Biophysics, Group Protein X-ray Crystallography and Signal Transduction, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and BIH, Berlin, Germany
| | - Katja Derkow
- Institute of Cell Biology and Neurobiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health (BIH), Berlin, Germany
| | | | - Carola Schipke
- Department of Psychiatry and Psychotherapy, and.,Experimental and Clinical Research Center, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and BIH.,German Center for Neurodegenerative Diseases, Berlin, Germany
| | - Claus Scheidereit
- Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany
| | - Harald Stachelscheid
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, BIH, Berlin-Brandenburg Center for Regenerative Therapies, Berlin, Germany
| | - Douglas Golenbock
- Division of Infectious Diseases and Immunology, Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, USA
| | - Oliver Peters
- Department of Psychiatry and Psychotherapy, and.,Experimental and Clinical Research Center, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and BIH.,German Center for Neurodegenerative Diseases, Berlin, Germany
| | - Michael Coleman
- Babraham Institute and John van Geest Centre for Brain Repair, University of Cambridge, Cambridge, United Kingdom
| | - Frank L Heppner
- NeuroCure Cluster of Excellence.,Department of Neuropathology.,German Center for Neurodegenerative Diseases, Berlin, Germany
| | - Patrick Scheerer
- Institute for Medical Physics and Biophysics, Group Protein X-ray Crystallography and Signal Transduction, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and BIH, Berlin, Germany.,German Centre for Cardiovascular Research, partner site Berlin, Berlin, Germany
| | - Victor Tarabykin
- Institute of Cell Biology and Neurobiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health (BIH), Berlin, Germany
| | - Klemens Ruprecht
- Department of Neurology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and BIH, Berlin, Germany
| | - Zsuzsanna Izsvák
- Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany
| | - Jens Mayer
- Institute of Human Genetics, Universität des Saarlandes, Hamburg, Germany
| | - Seija Lehnardt
- Institute of Cell Biology and Neurobiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health (BIH), Berlin, Germany.,Department of Neurology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and BIH, Berlin, Germany
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8
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Canli T. A model of human endogenous retrovirus (HERV) activation in mental health and illness. Med Hypotheses 2019; 133:109404. [PMID: 31557593 DOI: 10.1016/j.mehy.2019.109404] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Accepted: 09/18/2019] [Indexed: 01/04/2023]
Abstract
Despite strong evidence for the heritability of major depressive disorder (MDD), efforts to identify causal genes have been disappointing. Furthermore, although there is strong support for life stress as a major predictor of MDD, there are also considerable individual differences in susceptibility and resilience that remain poorly understood. Efforts to identify specific gene-by-environment risk factors produced results that were initially encouraging, but that were not supported by later large-scale studies. Here I propose a novel mechanism that could address the "missing heritability" of MDD, the role of environmental risk factors, and individual differences in susceptibility and resilience. This mechanism focuses on a class of transposable elements, Human Endogenous Retroviruses (HERVs), which make up approximately 8% of the human genome as the result of ancient retroviral infections that entered mammalian germ lines throughout the course of evolution. My primary hypothesis is that exposure to either exogenous viruses or traumatic experiences can activate HERVs in the brain to cause depressive (and possibly other psychiatric) symptoms. My secondary hypothesis is that individual differences in vulnerability or resilience result from the balance of activated HERVs with pathogenic versus protective functions in the brain. Future research can test these hypotheses by analysis of postmortem human brain tissue from donors with known viral or trauma histories; animal studies manipulating HERV expression; cell culture studies examining regulatory mechanisms of HERV expression; and from brain imaging studies of individuals with known HERV-expression. Such research may reveal novel functions of HERVs in neural tissue and may lead to a new generation of psychiatric interventions designed to target aberrant HERV activation.
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MESH Headings
- Animals
- Brain/virology
- Cells, Cultured
- Cytokines/physiology
- Depressive Disorder, Major/etiology
- Depressive Disorder, Major/genetics
- Depressive Disorder, Major/immunology
- Depressive Disorder, Major/virology
- Disease Models, Animal
- Endogenous Retroviruses/genetics
- Endogenous Retroviruses/physiology
- Environmental Exposure
- Epigenesis, Genetic
- Gene Expression Regulation, Viral
- Gene-Environment Interaction
- Genes, Viral
- Humans
- Intercellular Signaling Peptides and Proteins/physiology
- Mice, Transgenic
- Models, Biological
- Models, Psychological
- Schizophrenia/pathology
- Schizophrenia/virology
- Stress, Psychological
- Terminal Repeat Sequences/genetics
- Virus Activation
- Virus Diseases/complications
- Virus Diseases/psychology
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Affiliation(s)
- Turhan Canli
- Departments of Psychology and Psychiatry, Stony Brook University, Stony Brook, NY 11794-2500, USA.
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9
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Tartaglione AM, Cipriani C, Chiarotti F, Perrone B, Balestrieri E, Matteucci C, Sinibaldi-Vallebona P, Calamandrei G, Ricceri L. Early Behavioral Alterations and Increased Expression of Endogenous Retroviruses Are Inherited Across Generations in Mice Prenatally Exposed to Valproic Acid. Mol Neurobiol 2018; 56:3736-3750. [DOI: 10.1007/s12035-018-1328-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Accepted: 08/22/2018] [Indexed: 12/12/2022]
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10
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Turnbull MG, Douville RN. Related Endogenous Retrovirus-K Elements Harbor Distinct Protease Active Site Motifs. Front Microbiol 2018; 9:1577. [PMID: 30072963 PMCID: PMC6058741 DOI: 10.3389/fmicb.2018.01577] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Accepted: 06/25/2018] [Indexed: 02/06/2023] Open
Abstract
Background: Endogenous retrovirus-K is a group of related genomic elements descending from retroviral infections in human ancestors. HML2 is the clade of these viruses which contains the most intact provirus copies. These elements can be transcribed and translated in healthy and diseased tissues, and some of them produce active retroviral enzymes, such as protease. Retroviral gene products, including protease, contribute to illness in exogenous retroviral infections. There are ongoing efforts to test anti-retroviral regimens against endogenous retroviruses. Herein, we examine the potential activity and diversity of human endogenous retrovirus-K proteases, and their potential for impact on immunity and human disease. Results: Sequences similar to the endogenous retrovirus-K HML2 protease and reverse transcriptase were identified in the human genome, classified by phylogenetic inference and compared to Repbase reference sequences. The topologies of trees inferred from protease and reverse transcriptase sequences were similar and agreed with the classification using reference sequences. Surprisingly, only 62/480 protease sequences identified by BLAST were classified as HML2; the remainder were classified as other HML groups, with the majority (216) classified as HML3. Variation in functionally significant protease motifs was explored, and two major active site variants were identified – the DTGAD variant is common in all groups, but the DTGVD motif appears limited to HML3, HML5, and HML6. Furthermore, distinct RNA expression patterns of protease variants are seen in disease states, such as amyotrophic lateral sclerosis, breast cancer, and prostate cancer. Conclusion: Transcribed ERVK proteases exhibit a diversity which could impact immunity and inhibitor-based treatments, and these facets should be considered when designing therapeutic regimens.
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Affiliation(s)
| | - Renée N Douville
- Department of Biology, University of Winnipeg, Winnipeg, MB, Canada.,Department of Immunology, University of Manitoba, Winnipeg, MB, Canada
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11
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High expression of Endogenous Retroviruses from intrauterine life to adulthood in two mouse models of Autism Spectrum Disorders. Sci Rep 2018; 8:629. [PMID: 29330412 PMCID: PMC5766538 DOI: 10.1038/s41598-017-19035-w] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Accepted: 12/12/2017] [Indexed: 12/19/2022] Open
Abstract
Retroelements, such as Human Endogenous Retroviruses (HERVs), have been implicated in many complex diseases, including neurological and neuropsychiatric disorders. Previously, we demonstrated a distinctive expression profile of specific HERV families in peripheral blood mononuclear cells from Autistic Spectrum Disorders (ASD) patients, suggesting their involvement in ASD. Here we used two distinct ASD mouse models: inbred BTBR T+tf/J mice and CD-1 outbred mice prenatally exposed to valproic acid. Whole embryos, blood and brain samples from the offspring were collected at different ages and the expression of several ERV families (ETnI, ETnII-α, ETnII-β, ETnII-γ, MusD and IAP), proinflammatory cytokines (IL-1β, IL-6 and TNF-α) and Toll-like receptors (TLR3 and TLR4) was assessed. In the two distinct mouse models analysed, the transcriptional activity of the ERV families was significant higher in comparison with corresponding controls, in whole embryos, blood and brain samples. Also the expression levels of the proinflammatory cytokines and TLRs were significantly higher than controls. Current results are in agreement with our previous findings in ASD children, supporting the hypothesis that ERVs may serve as biomarkers of atypical brain development. Moreover, the changes in ERVs and proinflammatory cytokines expression could be related with the autistic-like traits acquisition in the two mouse models.
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12
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Douville RN, Nath A. Human Endogenous Retrovirus-K and TDP-43 Expression Bridges ALS and HIV Neuropathology. Front Microbiol 2017; 8:1986. [PMID: 29075249 PMCID: PMC5641584 DOI: 10.3389/fmicb.2017.01986] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Accepted: 09/27/2017] [Indexed: 12/12/2022] Open
Abstract
Despite the repetitive association of endogenous retroviruses in human disease, the mechanisms behind their pathological contributions remain to be resolved. Here we discuss how neuronal human endogenous retrovirus-K (HERV-K) expression in human immunodeficiency virus (HIV)-infected individuals is a distinct pathological aspect of HIV-associated neurological conditions, such as HIV encephalitis and HIV-associated neurocognitive disorders. Enhanced neuronal HERV-K levels were observed in the majority of HIV-infected individuals, and to a higher degree in brain tissue marked by HIV replication. Moreover, we highlight an important neuropathological overlap between amyotrophic lateral sclerosis and HIV encephalitis, that being the formation of neurotoxic TDP-43 deposits in neurons. Herein, we argue for enhanced transdisciplinary research in the field of ERV biology, using an example of how HERV-K expression has novel mechanistic and therapeutic implications for HIV neuropathology.
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Affiliation(s)
- Renée N Douville
- Department of Biology, University of Winnipeg, Winnipeg, MB, Canada.,Department of Immunology, University of Manitoba, Winnipeg, MB, Canada
| | - Avindra Nath
- Section of Infections of the Nervous System, National Institute of Neurological Diseases and Stroke, National Institutes of Health, Bethesda, MD, United States
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13
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Abstract
Infections of the nervous system are an important and challenging aspect of clinical neurology. Immediate correct diagnosis enables to introduce effective therapy, in conditions that without diagnosis may leave the patient with severe neurological incapacitation and sometimes even death. The cerebrospinal fluid (CSF) is a mirror that reflects nervous system pathology and can promote early diagnosis and therapy. The present chapter focuses on the CSF findings in neuro-infections, mainly viral and bacterial. Opening pressure, protein and glucose levels, presence of cells and type of the cellular reaction should be monitored. Other tests can also shed light on the causative agent: serology, culture, staining, molecular techniques such as polymerase chain reaction. Specific examination such as panbacterial and panfungal examinations should be examined when relevant. Our chapter is a guide-text that combines clinical presentation and course with CSF findings as a usuaful tool in diagnosis of neuroinfections.
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Affiliation(s)
- Felix Benninger
- Department of Neurology, Rabin Medical Center, Petach Tikva, Israel
| | - Israel Steiner
- Department of Neurology, Rabin Medical Center, Petach Tikva, Israel
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14
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Affiliation(s)
- Robert H Brown
- University of Massachusetts Medical School, Worcester, MA 01655, USA.
| | - Ammar Al-Chalabi
- Wohl Clinical Neuroscience Institute, King's College London and NIHR Dementia Biomedical Research Unit, London SE5 9RX, UK
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15
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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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16
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Manghera M, Ferguson-Parry J, Douville RN. TDP-43 regulates endogenous retrovirus-K viral protein accumulation. Neurobiol Dis 2016; 94:226-36. [PMID: 27370226 DOI: 10.1016/j.nbd.2016.06.017] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Revised: 05/30/2016] [Accepted: 06/27/2016] [Indexed: 12/12/2022] Open
Abstract
The concomitant expression of neuronal TAR DNA binding protein 43 (TDP-43) and human endogenous retrovirus-K (ERVK) is a hallmark of ALS. Since the involvement of TDP-43 in retrovirus replication remains controversial, we sought to evaluate whether TDP-43 exerts an effect on ERVK expression. In this study, TDP-43 bound the ERVK promoter in the context of inflammation or proteasome inhibition, with no effect on ERVK transcription. However, over-expression of ALS-associated aggregating forms of TDP-43, but not wild-type TDP-43, significantly enhanced ERVK viral protein accumulation. Human astrocytes and neurons further demonstrated cell-type specific differences in their ability to express and clear ERVK proteins during inflammation and proteasome inhibition. Astrocytes, but not neurons, were able to clear excess ERVK proteins through stress granule formation and autophagy. In vitro findings were validated in autopsy motor cortex tissue from patients with ALS and neuro-normal controls. We further confirmed marked enhancement of ERVK in cortical neurons of patients with ALS. Despite evidence of enhanced stress granule and autophagic response in ALS cortical neurons, these cells failed to clear excess ERVK protein accumulation. This highlights how multiple cellular pathways, in conjunction with disease-associated mutations, can converge to modulate the expression and clearance of viral gene products from genomic elements such as ERVK. In ALS, ERVK protein aggregation is a novel aspect of TDP-43 misregulation contributing towards the pathology of this neurodegenerative disease.
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Affiliation(s)
- Mamneet Manghera
- Department of Biology, University of Winnipeg, 599 Portage Avenue, Winnipeg, Manitoba R3B 2G3, Canada
| | - Jennifer Ferguson-Parry
- Department of Biology, University of Winnipeg, 599 Portage Avenue, Winnipeg, Manitoba R3B 2G3, Canada
| | - Renée N Douville
- Department of Biology, University of Winnipeg, 599 Portage Avenue, Winnipeg, Manitoba R3B 2G3, Canada; Department of Immunology, University of Manitoba, 750 McDermot Avenue, Winnipeg, Manitoba R3E 0T5, Canada.
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17
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Mortelmans K, Wang-Johanning F, Johanning GL. The role of human endogenous retroviruses in brain development and function. APMIS 2016; 124:105-15. [PMID: 26818265 DOI: 10.1111/apm.12495] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Accepted: 11/09/2015] [Indexed: 12/13/2022]
Abstract
Endogenous retroviral sequences are spread throughout the genome of all humans, and make up about 8% of the genome. Despite their prevalence, the function of human endogenous retroviruses (HERVs) in humans is largely unknown. In this review we focus on the brain, and evaluate studies in animal models that address mechanisms of endogenous retrovirus activation in the brain and central nervous system (CNS). One such study in mice found that TRIM28, a protein critical for mouse early development, regulates transcription and silencing of endogenous retroviruses in neural progenitor cells. Another intriguing finding in human brain cells and mouse models was that endogenous retrovirus HERV-K appears to be protective against neurotoxins. We also report on studies that associate HERVs with human diseases of the brain and CNS. There is little doubt of an association between HERVs and a number of CNS diseases. However, a cause and effect relationship between HERVs and these diseases has not yet been established.
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Affiliation(s)
- Kristien Mortelmans
- Discovery Biology Section, Biosciences Division, SRI International, Menlo Park, CA, USA
| | - Feng Wang-Johanning
- Discovery Biology Section, Biosciences Division, SRI International, Menlo Park, CA, USA
| | - Gary L Johanning
- Discovery Biology Section, Biosciences Division, SRI International, Menlo Park, CA, USA
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18
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19
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ERVK polyprotein processing and reverse transcriptase expression in human cell line models of neurological disease. Viruses 2015; 7:320-32. [PMID: 25609305 PMCID: PMC4306841 DOI: 10.3390/v7010320] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Revised: 12/02/2014] [Accepted: 01/12/2015] [Indexed: 12/03/2022] Open
Abstract
Enhanced expression of the reverse transcriptase (RT) protein encoded by human endogenous retrovirus-K (ERVK) is a promising biomarker for several inflammatory and neurological diseases. However, unlike RT enzymes encoded by exogenous retroviruses, little work has been done to identify ERVK RT isoforms, their expression patterns, and cellular localization. Using Western blot, we showcase the ERVK gag-pro-pol polyprotein processing leading to the production of several ERVK RT isoforms in human neuronal (ReNcell CX) and astrocytic (SVGA) models of neuroinflammatory disease. Since the pro-inflammatory cytokine IFNγ plays a key role in the pathology of several ERVK-associated neurological diseases, we sought to determine if IFNγ can drive ERVK RT expression. IFNγ signalling markedly enhanced ERVK polyprotein and RT expression in both human astrocytes and neurons. RT isoforms were expressed in a cell-type specific pattern and the RT-RNase H form was significantly increased with IFNγ treatment. Fluorescent imaging revealed distinct cytoplasmic, perinuclear and nuclear ERVK RT staining patterns upon IFNγ stimulation of astrocytes and neurons. These findings indicate that ERVK expression is inducible under inflammatory conditions such as IFNγ exposure—and thus, these newly established in vitro models may be useful in exploring ERVK biology in the context of neuroinflammatory disease.
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