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Guo Y, Li TD, Modzelewski AJ, Siomi H. Retrotransposon renaissance in early embryos. Trends Genet 2024; 40:39-51. [PMID: 37949723 DOI: 10.1016/j.tig.2023.10.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2023] [Revised: 10/13/2023] [Accepted: 10/16/2023] [Indexed: 11/12/2023]
Abstract
Despite being the predominant genetic elements in mammalian genomes, retrotransposons were often dismissed as genomic parasites with ambiguous biological significance. However, recent studies reveal their functional involvement in early embryogenesis, encompassing crucial processes such as zygotic genome activation (ZGA) and cell fate decision. This review underscores the paradigm shift in our understanding of retrotransposon roles during early preimplantation development, as well as their rich functional reservoir that is exploited by the host to provide cis-regulatory elements, noncoding RNAs, and functional proteins. The rapid advancement in long-read sequencing, low input multiomics profiling, advanced in vitro systems, and precise gene editing techniques encourages further dissection of retrotransposon functions that were once obscured by the intricacies of their genomic footprints.
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Affiliation(s)
- Youjia Guo
- Department of Molecular Biology, Keio University School of Medicine, Shinjuku, Tokyo 160-8582, Japan
| | - Ten D Li
- Department of Biomedical Sciences, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104-4539, USA
| | - Andrew J Modzelewski
- Department of Biomedical Sciences, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104-4539, USA.
| | - Haruhiko Siomi
- Department of Molecular Biology, Keio University School of Medicine, Shinjuku, Tokyo 160-8582, Japan; Human Biology Microbiome Quantum Research Center (WPI-Bio2Q), Keio University, Tokyo 160-8582, Japan.
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2
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Engel K, Wieland L, Krüger A, Volkmer I, Cynis H, Emmer A, Staege MS. Identification of Differentially Expressed Human Endogenous Retrovirus Families in Human Leukemia and Lymphoma Cell Lines and Stem Cells. Front Oncol 2021; 11:637981. [PMID: 33996550 PMCID: PMC8117144 DOI: 10.3389/fonc.2021.637981] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Accepted: 04/13/2021] [Indexed: 12/29/2022] Open
Abstract
Endogenous retroviruses (ERVs) are becoming more and more relevant in cancer research and might be potential targets. The oncogenic potential of human ERVs (HERVs) has been recognized and includes immunosuppression, cell fusion, antigenicity of viral proteins, and regulation of neighboring genes. To decipher the role of HERVs in human cancers, we used a bioinformatics approach and analyzed RNA sequencing data from the LL-100 panel, covering 22 entities of hematopoietic neoplasias including T cell, B cell and myeloid malignancies. We compared HERV expression in this panel with hematopoietic stem cells (HSCs), embryonic stem cells (ESCs) and normal blood cells. RNA sequencing data were mapped against a comprehensive synthetic viral metagenome with 116 HERV sequences from 14 different HERV families. Of these, 13 HERV families and elements were differently expressed in malignant hematopoietic cells and stem cells. We found transcriptional upregulation of HERVE family in acute megakaryocytic and erythroid leukemia and of HERVFc family in multiple myeloma/plasma cell leukemia (PCL). The HERVFc member HERVFc-1 was found transcriptionally active in the multiple myeloma cell line OPM-2 and also in the Hodgkin lymphoma cell line L-428. The expression of HERVFc-1 in L-428 cells was validated by qRT-PCR. We also confirm transcriptional downregulation of ERV3 in acute megakaryocytic and erythroid leukemia, and HERVK in acute monocytic and myelocytic leukemia and a depression of HERVF in all malignant entities. Most of the higher expressed HERV families could be detected in stem cells including HERVK (HML-2), HERV-like, HERVV, HERVT, ERV9, HERVW, HERVF, HERVMER, ERV3, HERVH and HERVPABLB.
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Affiliation(s)
- Kristina Engel
- Department of Surgical and Conservative Pediatrics and Adolescent Medicine, Martin Luther University Halle-Wittenberg, Halle, Germany
| | - Lisa Wieland
- Department of Surgical and Conservative Pediatrics and Adolescent Medicine, Martin Luther University Halle-Wittenberg, Halle, Germany.,Department of Neurology, Martin Luther University Halle-Wittenberg, Halle, Germany
| | - Anna Krüger
- Department of Surgical and Conservative Pediatrics and Adolescent Medicine, Martin Luther University Halle-Wittenberg, Halle, Germany
| | - Ines Volkmer
- Department of Surgical and Conservative Pediatrics and Adolescent Medicine, Martin Luther University Halle-Wittenberg, Halle, Germany
| | - Holger Cynis
- Department of Drug Design and Target Validation, Fraunhofer Institute for Cell Therapy and Immunology, Halle, Germany
| | - Alexander Emmer
- Department of Neurology, Martin Luther University Halle-Wittenberg, Halle, Germany
| | - Martin S Staege
- Department of Surgical and Conservative Pediatrics and Adolescent Medicine, Martin Luther University Halle-Wittenberg, Halle, Germany
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van der Kuyl AC. Contemporary Distribution, Estimated Age, and Prehistoric Migrations of Old World Monkey Retroviruses. EPIDEMIOLGIA (BASEL, SWITZERLAND) 2021; 2:46-67. [PMID: 36417189 PMCID: PMC9620922 DOI: 10.3390/epidemiologia2010005] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 01/18/2021] [Accepted: 01/29/2021] [Indexed: 12/14/2022]
Abstract
Old World monkeys (OWM), simians inhabiting Africa and Asia, are currently affected by at least four infectious retroviruses, namely, simian foamy virus (SFV), simian immunodeficiency virus (SIV), simian T-lymphotropic virus (STLV), and simian type D retrovirus (SRV). OWM also show chromosomal evidence of having been infected in the past with four more retroviral species, baboon endogenous virus (BaEV), Papio cynocephalus endogenous virus (PcEV), simian endogenous retrovirus (SERV), and Rhesus endogenous retrovirus-K (RhERV-K/SERV-K1). For some of the viruses, transmission to other primates still occurs, resulting, for instance, in the HIV pandemic. Retroviruses are intimately connected with their host as they are normally spread by close contact. In this review, an attempt to reconstruct the distribution and history of OWM retroviruses will be made. A literature overview of the species infected by any of the eight retroviruses as well as an age estimation of the pathogens will be given. In addition, primate genomes from databases have been re-analyzed for the presence of endogenous retrovirus integrations. Results suggest that some of the oldest retroviruses, SERV and PcEV, have travelled with their hosts to Asia during the Miocene, when a higher global temperature allowed simian expansions. In contrast, younger viruses, such as SIV and SRV, probably due to the lack of a primate continuum between the continents in later times, have been restricted to Africa and Asia, respectively.
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Affiliation(s)
- Antoinette C van der Kuyl
- Laboratory of Experimental Virology, Department of Medical Microbiology, Amsterdam UMC, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands
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4
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Gifford RJ, Blomberg J, Coffin JM, Fan H, Heidmann T, Mayer J, Stoye J, Tristem M, Johnson WE. Nomenclature for endogenous retrovirus (ERV) loci. Retrovirology 2018; 15:59. [PMID: 30153831 PMCID: PMC6114882 DOI: 10.1186/s12977-018-0442-1] [Citation(s) in RCA: 85] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2018] [Accepted: 08/20/2018] [Indexed: 11/10/2022] Open
Abstract
Retroviral integration into germline DNA can result in the formation of a vertically inherited proviral sequence called an endogenous retrovirus (ERV). Over the course of their evolution, vertebrate genomes have accumulated many thousands of ERV loci. These sequences provide useful retrospective information about ancient retroviruses, and have also played an important role in shaping the evolution of vertebrate genomes. There is an immediate need for a unified system of nomenclature for ERV loci, not only to assist genome annotation, but also to facilitate research on ERVs and their impact on genome biology and evolution. In this review, we examine how ERV nomenclatures have developed, and consider the possibilities for the implementation of a systematic approach for naming ERV loci. We propose that such a nomenclature should not only provide unique identifiers for individual loci, but also denote orthologous relationships between ERVs in different species. In addition, we propose that-where possible-mnemonic links to previous, well-established names for ERV loci and groups should be retained. We show how this approach can be applied and integrated into existing taxonomic and nomenclature schemes for retroviruses, ERVs and transposable elements.
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Affiliation(s)
- Robert J Gifford
- MRC-University of Glasgow Centre for Virus Research, Glasgow, UK.
| | - Jonas Blomberg
- Department of Medical Sciences, Uppsala University, Uppsala, Sweden
| | - John M Coffin
- Department of Molecular Biology and Microbiology, Tufts University, Boston, MA, USA
| | - Hung Fan
- Department of Molecular Biology and Biochemistry and Cancer Research Institute, University of California, Irvine, CA, 92697, USA
| | - Thierry Heidmann
- Department of Molecular Physiology and Pathology of Infectious and Endogenous Retroviruses, CNRS UMR 9196, Institut Gustave Roussy, 94805, Villejuif, France
| | - Jens Mayer
- Department of Human Genetics, Center of Human and Molecular Biology, Medical Faculty, University of Saarland, Homburg, Germany
| | - Jonathan Stoye
- The Francis Crick Institute, Mill Hill Laboratory, The Ridgeway, Mill Hill, London, UK
| | - Michael Tristem
- Imperial College London, Silwood Park Campus, Buckhurst Road, Ascot, Berkshire, SL5 7PY, UK
| | - Welkin E Johnson
- Biology Department, Boston College, Chestnut Hill, Massachusetts, 02467, USA.
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Blanco-Melo D, Gifford RJ, Bieniasz PD. Reconstruction of a replication-competent ancestral murine endogenous retrovirus-L. Retrovirology 2018; 15:34. [PMID: 29716624 PMCID: PMC5930517 DOI: 10.1186/s12977-018-0416-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Accepted: 04/10/2018] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND About 10% of the mouse genome is composed of endogenous retroviruses (ERVs) that represent a molecular fossil record of past retroviral infections. One such retrovirus, murine ERV-L (MuERV-L) is an env-deficient ERV that has undergone episodic proliferation, with the most recent amplification occurring ~ 2 million years ago. MuERV-L related sequences have been co-opted by mice for antiretroviral defense, and possibly as promoters for some genes that regulate totipotency in early mouse embryos. However, MuERV-L sequences present in modern mouse genomes have not been observed to replicate. RESULTS Here, we describe the reconstruction of an ancestral MuERV-L (ancML) sequence through paleovirological analyses of MuERV-L elements in the modern mouse genome. The resulting MuERV-L (ancML) sequence was synthesized and a reporter gene embedded. The reconstructed MuERV-L (ancML) could replicate in a manner that is dependent on reverse transcription and generated de novo integrants. Notably, MuERV-L (ancML) exhibited a narrow host range. Interferon-α could reduce MuERV-L (ancML) replication, suggesting the existence of interferon-inducible genes that could inhibit MuERV-L replication. While mouse APOBEC3 was able to restrict the replication of MuERV-L (ancML), inspection of endogenous MuERV-L sequences suggested that the impact of APOBEC3 mediated hypermutation on MuERV-L has been minimal. CONCLUSION The reconstruction of an ancestral MuERV-L sequence highlights the potential for the retroviral fossil record to illuminate ancient events and enable studies of the impact of retroviral elements on animal evolution.
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Affiliation(s)
- Daniel Blanco-Melo
- Laboratory of Retrovirology and Howard Hughes Medical Institute, The Rockefeller University, New York, NY, USA
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Robert J Gifford
- MRC-University of Glasgow Centre for Virus Research, Glasgow, UK
| | - Paul D Bieniasz
- Laboratory of Retrovirology and Howard Hughes Medical Institute, The Rockefeller University, New York, NY, USA.
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Vargiu L, Rodriguez-Tomé P, Sperber GO, Cadeddu M, Grandi N, Blikstad V, Tramontano E, Blomberg J. Classification and characterization of human endogenous retroviruses; mosaic forms are common. Retrovirology 2016; 13:7. [PMID: 26800882 PMCID: PMC4724089 DOI: 10.1186/s12977-015-0232-y] [Citation(s) in RCA: 175] [Impact Index Per Article: 21.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Accepted: 12/16/2015] [Indexed: 02/06/2023] Open
Abstract
Background Human endogenous retroviruses (HERVs) represent the inheritance of ancient germ-line cell infections by exogenous retroviruses and the subsequent transmission of the integrated proviruses to the descendants. ERVs have the same internal structure as exogenous retroviruses. While no replication-competent HERVs have been recognized, some retain up to three of four intact ORFs. HERVs have been classified before, with varying scope and depth, notably in the RepBase/RepeatMasker system. However, existing classifications are bewildering. There is a need for a systematic, unifying and simple classification. We strived for a classification which is traceable to previous classifications and which encompasses HERV variation within a limited number of clades. Results The human genome assembly GRCh 37/hg19 was analyzed with RetroTector, which primarily detects relatively complete Class I and II proviruses. A total of 3173 HERV sequences were identified. The structure of and relations between these proviruses was resolved through a multi-step classification procedure that involved a novel type of similarity image analysis (“Simage”) which allowed discrimination of heterogeneous (noncanonical) from homogeneous (canonical) HERVs. Of the 3173 HERVs, 1214 were canonical and segregated into 39 canonical clades (groups), belonging to class I (Gamma- and Epsilon-like), II (Beta-like) and III (Spuma-like). The groups were chosen based on (1) sequence (nucleotide and Pol amino acid), similarity, (2) degree of fit to previously published clades, often from RepBase, and (3) taxonomic markers. The groups fell into 11 supergroups. The 1959 noncanonical HERVs contained 31 additional, less well-defined groups. Simage analysis revealed several types of mosaicism, notably recombination and secondary integration. By comparing flanking sequences, LTRs and completeness of gene structure, we deduced that some noncanonical HERVs proliferated after the recombination event. Groups were further divided into envelope subgroups (altogether 94) based on sequence similarity and characteristic “immunosuppressive domain” motifs. Intra and inter(super)group, as well as intraclass, recombination involving envelope genes (“env snatching”) was a common event. LTR divergence indicated that HERV-K(HML2) and HERVFC had the most recent integrations, HERVL and HUERSP3 the oldest. Conclusions A comprehensive HERV classification and characterization approach was undertaken. It should be applicable for classification of all ERVs. Recombination was common among HERV ancestors. Electronic supplementary material The online version of this article (doi:10.1186/s12977-015-0232-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Laura Vargiu
- Department of Life and Environmental Sciences, University of Cagliari, Cagliari, Italy. .,Center for Advanced Studies, Research and Development in Sardinia, CRS4, Pula, Italy. .,Nurideas S.r.l., Cagliari, Italy.
| | - Patricia Rodriguez-Tomé
- Center for Advanced Studies, Research and Development in Sardinia, CRS4, Pula, Italy. .,Nurideas S.r.l., Cagliari, Italy.
| | - Göran O Sperber
- Physiology Unit, Department of Neuroscience, Uppsala University, Uppsala, Sweden.
| | - Marta Cadeddu
- Department of Life and Environmental Sciences, University of Cagliari, Cagliari, Italy.
| | - Nicole Grandi
- Department of Life and Environmental Sciences, University of Cagliari, Cagliari, Italy.
| | - Vidar Blikstad
- Department of Medical Sciences, Uppsala University Hospital, Dag Hammarskjölds Väg 17, Uppsala, 751 85, Sweden.
| | - Enzo Tramontano
- Department of Life and Environmental Sciences, University of Cagliari, Cagliari, Italy.
| | - Jonas Blomberg
- Department of Medical Sciences, Uppsala University Hospital, Dag Hammarskjölds Väg 17, Uppsala, 751 85, Sweden.
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7
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Haase K, Mösch A, Frishman D. Differential expression analysis of human endogenous retroviruses based on ENCODE RNA-seq data. BMC Med Genomics 2015; 8:71. [PMID: 26530187 PMCID: PMC4632268 DOI: 10.1186/s12920-015-0146-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Accepted: 10/28/2015] [Indexed: 11/24/2022] Open
Abstract
Background Human endogenous retroviruses (HERVs) are flanked by long terminal repeats (LTRs), which possess promoter activity and can therefore influence the expression of neighboring genes. HERV involvement in different types of cancer has already been thoroughly documented. However, so far there has been no systematic study of HERV expression patterns in a multitude of cell types in health and disease. In particular, the publication of the comprehensive ENCODE dataset has already facilitated many gene expression studies, but none so far focusing exclusively on HERVs. Results We present a comprehensive differential analysis of HERV expression based on ENCODE Tier 1 and Tier 2 RNA-seq data produced by Cold Spring Harbor Laboratories and the California Institute of Technology. This analysis was conducted for individual HERV loci and for entire HERV families in twelve different cell lines, of which six correspond to the normal condition and the other six represent cancer cell types. Although the principal component analysis revealed that the two groups of cells show distinguishable expression patterns, we were not able to link these differences to one or multiple particular HERV families. Two samples exhibit expression patterns, which are not similar to the corresponding cell lines of the other producing lab. Instead they show signs of cancer formation and expression of the pluripotency marker HERVH, despite being classified as a normal cell line and a differentiated cell, respectively. Conclusions Our study demonstrates that ENCODE data are generally comparable between the different contributing labs and that the analysis of HERV elements can provide novel insights into differentiation and disease state of a cell that are easily overlooked when focusing on protein-coding genes. Our findings hint at a change in HERV expression during cancerogenesis. Electronic supplementary material The online version of this article (doi:10.1186/s12920-015-0146-5) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Kerstin Haase
- Department of Genome Oriented Bioinformatics, Wissenschaftszentrum Weihenstephan, TU München, Maximus-von-Imhof-Forum 3, Freising, 85354, Germany.
| | - Anja Mösch
- Department of Genome Oriented Bioinformatics, Wissenschaftszentrum Weihenstephan, TU München, Maximus-von-Imhof-Forum 3, Freising, 85354, Germany.
| | - Dmitrij Frishman
- Department of Genome Oriented Bioinformatics, Wissenschaftszentrum Weihenstephan, TU München, Maximus-von-Imhof-Forum 3, Freising, 85354, Germany. .,Helmholtz Center Munich - German Research Center for Environmental Health (GmbH), Institute of Bioinformatics and Systems Biology, Ingolstädter Landstraße 1, Neuherberg, 85764, Germany. .,St Petersburg State Polytechnical University, St. Petersburg, 195251, Russia.
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8
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Hizi A, Herzig E. dUTPase: the frequently overlooked enzyme encoded by many retroviruses. Retrovirology 2015; 12:70. [PMID: 26259899 PMCID: PMC4531489 DOI: 10.1186/s12977-015-0198-9] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2015] [Accepted: 08/04/2015] [Indexed: 11/13/2022] Open
Abstract
Retroviruses are among the best studied viruses in last decades due to their pivotal involvement in cellular processes and, most importantly, in causing human diseases, most notably-acquired immunodeficiency syndrome (AIDS) that is triggered by human immunodeficiency viruses types 1 and 2 (HIV-1 and HIV-2, respectively). Numerous studied were conducted to understand the involvement of the three cardinal retroviral enzymes, reverse transcriptase, integrase and protease, in the life cycle of the viruses. These studies have led to the development of many inhibitors of these enzymes as anti-retroviral specific drugs that are used for routine treatments of HIV/AIDS patients. Interestingly, a fourth virus-encoded enzyme, the deoxyuridine 5'-triphosphate nucleotidohydrolase (dUTPase) is also found in several major retroviral groups. The presence and the importance of this enzyme to the life cycle of retroviruses were usually overlooked by most retrovirologists, although the occurrence of dUTPases, particularly in beta-retroviruses and in non-primate retroviruses, is known for more than 20 years. Only more recently, retroviral dUTPases were brought into the limelight and were shown in several cases to be essential for viral replication. Therefore, it is likely that future studies on this enzyme will advance our knowledge to a level that will allow designing novel, specific and potent anti-dUTPase drugs that are effective in combating retroviral diseases. The aim of this review is to give concise background information on dUTPases in general and to summarize the most relevant data on retroviral dUTPases and their involvement in the replication processes and pathogenicity of the viruses, as well as in possibly-associated human diseases.
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Affiliation(s)
- Amnon Hizi
- Department of Cell and Developmental Biology, Sackler School of Medicine, Tel Aviv University, 69978, Tel Aviv, Israel.
| | - Eytan Herzig
- Department of Cell and Developmental Biology, Sackler School of Medicine, Tel Aviv University, 69978, Tel Aviv, Israel.
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9
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A novel recombinant retrovirus in the genomes of modern birds combines features of avian and mammalian retroviruses. J Virol 2013; 88:2398-405. [PMID: 24352464 DOI: 10.1128/jvi.02863-13] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Endogenous retroviruses (ERVs) represent ancestral sequences of modern retroviruses or their extinct relatives. The majority of ERVs cluster alongside exogenous retroviruses into two main groups based on phylogenetic analyses of the reverse transcriptase (RT) enzyme. Class I includes gammaretroviruses, and class II includes lentiviruses and alpha-, beta-, and deltaretroviruses. However, analyses of the transmembrane subunit (TM) of the envelope glycoprotein (env) gene result in a different topology for some retroviruses, suggesting recombination events in which heterologous env sequences have been acquired. We previously demonstrated that the TM sequences of five of the six genera of orthoretroviruses can be divided into three types, each of which infects a distinct set of vertebrate classes. Moreover, these classes do not always overlap the host range of the associated RT classes. Thus, recombination resulting in acquisition of a heterologous env gene could in theory facilitate cross-species transmissions across vertebrate classes, for example, from mammals to reptiles. Here we characterized a family of class II avian ERVs, "TgERV-F," that acquired a mammalian gammaretroviral env sequence. Although TgERV-F clusters near a sister clade to alpharetroviruses, its genome also has some features of betaretroviruses. We offer evidence that this unusual recombinant has circulated among several avian orders and may still have infectious members. In addition to documenting the infection of a nongalliform avian species by a mammalian retrovirus, TgERV-F also underscores the importance of env sequences in reconstructing phylogenies and supports a possible role for env swapping in allowing cross-species transmissions across wide taxonomic distances. IMPORTANCE Retroviruses can sometimes acquire an envelope gene (env) from a distantly related retrovirus. Since env is a key determinant of host range, such an event affects the host range of the recombinant virus and can lead to the creation of novel retroviral lineages. Retroviruses insert viral DNA into the host DNA during infection, and therefore vertebrate genomes contain a "fossil record" of endogenous retroviral sequences thought to represent past infections of germ cells. We examined endogenous retroviral sequences in avian genomes for evidence of recombination events involving env. Although cross-species transmissions of retroviruses between vertebrate classes (from mammals to birds, for example) are thought to be rare, we here characterized a group of avian retroviruses that acquired an env sequence from a mammalian retrovirus. We offer evidence that this unusual recombinant circulated among songbirds 2 to 4 million years ago and has remained active into the recent past.
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10
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Rethwilm A, Bodem J. Evolution of foamy viruses: the most ancient of all retroviruses. Viruses 2013; 5:2349-74. [PMID: 24072062 PMCID: PMC3814592 DOI: 10.3390/v5102349] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2013] [Revised: 08/27/2013] [Accepted: 09/18/2013] [Indexed: 12/24/2022] Open
Abstract
Recent evidence indicates that foamy viruses (FVs) are the oldest retroviruses (RVs) that we know and coevolved with their hosts for several hundred million years. This coevolution may have contributed to the non-pathogenicity of FVs, an important factor in development of foamy viral vectors in gene therapy. However, various questions on the molecular evolution of FVs remain still unanswered. The analysis of the spectrum of animal species infected by exogenous FVs or harboring endogenous FV elements in their genome is pivotal. Furthermore, animal studies might reveal important issues, such as the identification of the FV in vivo target cells, which than require a detailed characterization, to resolve the molecular basis of the accuracy with which FVs copy their genome. The issues of the extent of FV viremia and of the nature of the virion genome (RNA vs. DNA) also need to be experimentally addressed.
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Affiliation(s)
- Axel Rethwilm
- Universität Würzburg, Institut für Virologie und Immunbiologie, Versbacher Str.7, Würzburg 97078, Germany.
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11
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Lee A, Nolan A, Watson J, Tristem M. Identification of an ancient endogenous retrovirus, predating the divergence of the placental mammals. Philos Trans R Soc Lond B Biol Sci 2013; 368:20120503. [PMID: 23938752 PMCID: PMC3758187 DOI: 10.1098/rstb.2012.0503] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The evolutionary arms race between mammals and retroviruses has long been recognized as one of the oldest host-parasite interactions. Rapid evolution rates in exogenous retroviruses have often made accurate viral age estimations highly problematic. Endogenous retroviruses (ERVs), however, integrate into the germline of their hosts, and are subjected to their evolutionary rates. This study describes, for the first time, a retroviral orthologue predating the divergence of placental mammals, giving it a minimum age of 104-110 Myr. Simultaneously, other orthologous selfish genetic elements (SGEs), inserted into the ERV sequence, provide evidence for the oldest individual mammalian-wide interspersed repeat and medium-reiteration frequency interspersed repeat mammalian repeats, with the same minimum age. The combined use of shared SGEs and reconstruction of viral orthologies defines new limits and increases maximum 'lookback' times, with subsequent implications for the field of paleovirology.
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Affiliation(s)
- Adam Lee
- Imperial College London, South Kensington Campus, London SW7 2AZ, UK
| | - Alison Nolan
- Imperial College London, Silwood Park Campus, Buckhurst Road, Ascot, Berkshire SL5 7PY, UK
| | - Jason Watson
- Imperial College London, Silwood Park Campus, Buckhurst Road, Ascot, Berkshire SL5 7PY, UK
| | - Michael Tristem
- Imperial College London, Silwood Park Campus, Buckhurst Road, Ascot, Berkshire SL5 7PY, UK
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12
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Abstract
The majority of retroviral envelope glycoproteins characterized to date are typical of type I viral fusion proteins, having a receptor binding subunit associated with a fusion subunit. The fusion subunits of lentiviruses and alpha-, beta-, delta- and gammaretroviruses have a very conserved domain organization and conserved features of secondary structure, making them suitable for phylogenetic analyses. Such analyses, along with sequence comparisons, reveal evidence of numerous recombination events in which retroviruses have acquired envelope glycoproteins from heterologous sequences. Thus, the envelope gene (env) can have a history separate from that of the polymerase gene (pol), which is the most commonly used gene in phylogenetic analyses of retroviruses. Focusing on the fusion subunits of the genera listed above, we describe three distinct types of retroviral envelope glycoproteins, which we refer to as gamma-type, avian gamma-type and beta-type. By tracing these types within the ‘fossil record’ provided by endogenous retroviruses, we show that they have surprisingly distinct evolutionary histories and dynamics, with important implications for cross-species transmissions and the generation of novel lineages. These findings validate the utility of env sequences in contributing phylogenetic signal that enlarges our understanding of retrovirus evolution.
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Affiliation(s)
- Jamie E Henzy
- Biology Department, Boston College, , Chestnut Hill, MA 02467, USA
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13
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Gifford WD, Pfaff SL, Macfarlan TS. Transposable elements as genetic regulatory substrates in early development. Trends Cell Biol 2013; 23:218-26. [PMID: 23411159 DOI: 10.1016/j.tcb.2013.01.001] [Citation(s) in RCA: 93] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2012] [Revised: 12/17/2012] [Accepted: 01/03/2013] [Indexed: 01/07/2023]
Abstract
The abundance and ancient origins of transposable elements (TEs) in eukaryotic genomes has spawned research into the potential symbiotic relationship between these elements and their hosts. In this review, we introduce the diversity of TEs, discuss how distinct classes are uniquely regulated in development, and describe how they appear to have been coopted for the purposes of gene regulation and the orchestration of a number of processes during early embryonic development. Although young, active TEs play an important role in somatic tissues and evolution, we focus mostly on the contributions of the older, fixed elements in mammalian genomes. We also discuss major challenges inherent in the study of TEs and contemplate future experimental approaches to further investigate how they coordinate developmental processes.
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Affiliation(s)
- Wesley D Gifford
- Gene Expression Laboratory and the Howard Hughes Medical Institute, The Salk Institute for Biological Studies, 10010 North Torrey Pines, La Jolla, CA 92037, USA
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14
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Abstract
Retroviral replication involves the formation of a DNA provirus integrated into the host genome. Through this process, retroviruses can colonize the germ line to form endogenous retroviruses (ERVs). ERV inheritance can have multiple adverse consequences for the host, some resembling those resulting from exogenous retrovirus infection but others arising by mechanisms unique to ERVs. Inherited retroviruses can also confer benefits on the host. To meet the different threats posed by endogenous and exogenous retroviruses, various host defences have arisen during evolution, acting at various stages on the retrovirus life cycle. In this Review, I describe our current understanding of the distribution and architecture of ERVs, the consequences of their acquisition for the host and the emerging details of the intimate evolutionary relationship between virus and vertebrate host.
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15
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Ramulu HG, Raoult D, Pontarotti P. The rhizome of life: what about metazoa? Front Cell Infect Microbiol 2012; 2:50. [PMID: 22919641 PMCID: PMC3417402 DOI: 10.3389/fcimb.2012.00050] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2012] [Accepted: 03/23/2012] [Indexed: 02/03/2023] Open
Abstract
The increase in huge number of genomic sequences in recent years has contributed to various genetic events such as horizontal gene transfer (HGT), gene duplication and hybridization of species. Among them HGT has played an important role in the genome evolution and was believed to occur only in Bacterial and Archaeal genomes. As a result, genomes were found to be chimeric and the evolution of life was represented in different forms such as forests, networks and species evolution was described more like a rhizome, rather than a tree. However, in the last few years, HGT has also been evidenced in other group such as metazoa (for example in root-knot nematodes, bdelloid rotifers and mammals). In addition to HGT, other genetic events such as transfer by retrotransposons and hybridization between more closely related lineages are also well established. Therefore, in the light of such genetic events, whether the evolution of metazoa exists in the form of a tree, network or rhizome is highly questionable and needs to be determined. In the current review, we will focus on the role of HGT, retrotransposons and hybridization in the metazoan evolution.
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Affiliation(s)
- Hemalatha G. Ramulu
- LATP UMR-CNRS 7353, Evolution Biologique et Modélisation, Aix-Marseille UniversitéeMarseille, France
- URMITE CNRS-IRD UMR6236-198Marseille, France
| | | | - Pierre Pontarotti
- LATP UMR-CNRS 7353, Evolution Biologique et Modélisation, Aix-Marseille UniversitéeMarseille, France
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16
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Discovery of retroviral homologs in bats: implications for the origin of mammalian gammaretroviruses. J Virol 2012; 86:4288-93. [PMID: 22318134 DOI: 10.1128/jvi.06624-11] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Gammaretroviruses infect a wide range of vertebrate species where they are associated with leukemias, neurological diseases and immunodeficiencies. However, the origin of these infectious agents is unknown. Through a phylogenetic analysis of viral gene sequences, we show that bats harbor an especially diverse set of gammaretroviruses. In particular, phylogenetic analysis places Rhinolophus ferrumequinum retrovirus (RfRV), a new gammaretrovirus identified by de novo analysis of the Rhinolophus ferrumequinum transcriptome, and six other gammaretroviruses from different bat species, as basal to other mammalian gammaretroviruses. An analysis of the similarity in the phylogenetic history between the gammaretroviruses and their bat hosts provided evidence for both host-virus codivergence and cross-species transmission. Taken together, these data provide new insights into the origin of the mammalian gammaretroviruses.
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17
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van der Kuyl AC. HIV infection and HERV expression: a review. Retrovirology 2012; 9:6. [PMID: 22248111 PMCID: PMC3311604 DOI: 10.1186/1742-4690-9-6] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2011] [Accepted: 01/16/2012] [Indexed: 12/24/2022] Open
Abstract
The human genome contains multiple copies of retrovirus genomes known as endogenous retroviruses (ERVs) that have entered the germ-line at some point in evolution. Several of these proviruses have retained (partial) coding capacity, so that a number of viral proteins or even virus particles are expressed under various conditions. Human ERVs (HERVs) belong to the beta-, gamma-, or spuma- retrovirus groups. Endogenous delta- and lenti- viruses are notably absent in humans, although endogenous lentivirus genomes have been found in lower primates. Exogenous retroviruses that currently form a health threat to humans intriguingly belong to those absent groups. The best studied of the two infectious human retroviruses is the lentivirus human immunodeficiency virus (HIV) which has an overwhelming influence on its host by infecting cells of the immune system. One HIV-induced change is the induction of HERV transcription, often leading to induced HERV protein expression. This review will discuss the potential HIV-HERV interactions. Several studies have suggested that HERV proteins are unlikely to complement defective HIV virions, nor is HIV able to package HERV transcripts, probably due to low levels of sequence similarity. It is unclear whether the expression of HERVs has a negative, neutral, or positive influence on HIV-AIDS disease progression. A positive effect was recently reported by the specific expression of HERVs in chronically HIV-infected patients, which results in the presentation of HERV-derived peptides to CD8+ T-cells. These cytotoxic T-cells were not tolerant to HERV peptides, as would be expected for self-antigens, and consequently lysed the HIV-infected, HERV-presenting cells. This novel mechanism could control HIV replication and result in a low plasma viral load. The possibility of developing a vaccination strategy based on these HERV peptides will be discussed.
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Affiliation(s)
- Antoinette C van der Kuyl
- Laboratory of Experimental Virology, Department of Medical Microbiology, Center for Infection and Immunity Amsterdam, Academic Medical Center of the University of Amsterdam, Meibergdreef 15, 1105 AZ Amsterdam, The Netherlands.
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18
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Characterization of a Xenopus tropicalis endogenous retrovirus with developmental and stress-dependent expression. J Virol 2010; 85:2167-79. [PMID: 21159866 DOI: 10.1128/jvi.01979-10] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We report on the identification and characterization of XTERV1, a full-length endogenous retrovirus (ERV) within the genome of the western clawed frog (Xenopus tropicalis). XTERV1 contains all the basic genetic elements common to ERVs, including the classical 5'-long terminal repeat (LTR)-gag-pol-env-3'-LTR architecture, as well as conserved functional motifs inherent to each retroviral protein. Using phylogenetic analysis, we show that XTERV1 is related to the Epsilonretrovirus genus. The X. tropicalis genome harbors a single full-length copy with intact gag and pol open reading frames that localizes to the centromeric region of chromosome 5. About 10 full-length defective copies of XTERV1 are found interspersed in the genome, and 2 of them could be assigned to chromosomes 1 and 3. We find that XTERV1 genes are zygotically transcribed in a regulated spatiotemporal manner during frog development, including metamorphosis. Moreover, XTERV1 transcription is upregulated under certain cellular stress conditions, including cytotoxic and metabolic stresses. Interestingly, XTERV1 Env is found to be homologous to FR47, a protein upregulated following cold exposure in the freeze-tolerant wood frog (Rana sylvatica). In addition, we find that R. sylvatica FR47 mRNA originated from a retroviral element. We discuss the potential role(s) of ERVs in physiological processes in vertebrates.
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Oliveira NMM, Trikha R, McKnight Á. A novel envelope mediated post entry restriction of murine leukaemia virus in human cells is Ref1/TRIM5α independent. Retrovirology 2010; 7:81. [PMID: 20929586 PMCID: PMC2959036 DOI: 10.1186/1742-4690-7-81] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2009] [Accepted: 10/07/2010] [Indexed: 11/23/2022] Open
Abstract
BACKGROUND 'Intrinsic' resistance to retroviral infection was first recognised with the Friend virus susceptibility gene (Fv1), which determines susceptibility to murine leukaemia virus (MLV) infection in different murine species. Similarly, the tripartite motif (TRIM) family of proteins determine lentiviral restriction in a primate host-species specific manner. For example rhesus TRIM5α (rhTRIM5α) can potently restrict HIV-1 infection while human TRIM5α (huTRIM5α) only has a mild effect on SIVmac and HIV-1 infectivity (Lv1). Human TRIM5α is able to restrict MLV-N virus replication, but is ineffective against MLV-B or MLV-NB virus infection. Lv2 restriction of some HIV-2 viruses is seen in human cells. Like Lv1, Lv2 is a post-entry restriction factor, whose viral determinants have been mapped to the viral capsid (CA). Unlike Lv1, however, Lv2 is determined by envelope (Env) in addition to CA. Here we present evidence of a novel Env determined post entry restriction to infection in human cells of pseudotyped MLV-B and MLV-NB cores. RESULTS We generated retroviral vectors pseudotyped with various gamma and lentiviral Envs on MLV-B and -NB CAs containing a green fluorescent protein (GFP) reporter. Flow cytometry was used to determine transduction efficiencies in NP2/CD4/CXCR4 (glioma cell line stably transduced with the HIV receptors) and HeLa/CD4 cell lines. The HeLa/CD4 cell line restricted both MLV CAs in an Env dependent manner, compared to NP2/CD4/CXCR4 cells. Quantitative polymerase chain reaction (QT-PCR) analysis of reverse transcription (RT) transcripts demonstrates that this restriction occurs at a post entry and RT level. siRNA knockdown of huTRIM5α ruled out a direct role for this cellular component in mediating this restriction. We describe a previously unobserved Env determined restriction of MLV-B and MLV-NB CAs in HeLa/CD4 cells when pseudotyped with HIV-2 and RD114 Envs, but not gibbon ape leukaemia virus (GALV), HIV-1 or Amphotrophic (Ampho) Envs. CONCLUSIONS Our data further demonstrate the variability of Env and CA mediated susceptibility to post entry host cell restriction. We discuss the relevance of these findings in light of the growing evidence supporting the complexities involved in innate host immunity to retroviral infection.
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Affiliation(s)
- Nidia MM Oliveira
- HIV/AIDS Group, Centre for Immunology and Infectious Disease, Blizard Institute of Cell and Molecular Science, Barts and the London School of Medicine and Dentistry, 4 Newark Street, Whitechapel, London E1 2AT, UK
| | - Roochi Trikha
- HIV/AIDS Group, Centre for Immunology and Infectious Disease, Blizard Institute of Cell and Molecular Science, Barts and the London School of Medicine and Dentistry, 4 Newark Street, Whitechapel, London E1 2AT, UK
| | - Áine McKnight
- HIV/AIDS Group, Centre for Immunology and Infectious Disease, Blizard Institute of Cell and Molecular Science, Barts and the London School of Medicine and Dentistry, 4 Newark Street, Whitechapel, London E1 2AT, UK
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20
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Human endogenous retroviral long terminal repeat sequences as cell type-specific promoters in retroviral vectors. J Virol 2009; 83:12643-50. [PMID: 19741000 DOI: 10.1128/jvi.00858-09] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The human genome contains more than half a million human endogenous retrovirus (HERV) long terminal repeats (LTRs) that can be regarded as mobile regulatory modules. Many of these HERV LTRs have been recruited during evolution as transcriptional control elements for cellular gene expression. We have cloned LTR sequences from two HERV families, HERV-H and HERV-L, differing widely in their activity and tissue specificity into a murine leukemia virus (MLV)-based promoter conversion vector (ProCon). Various human cell lines were infected with the HERV-MLV hybrid vectors, and cell type-specific expression of the reporter gene was compared with the promoter specificity of the corresponding HERV LTRs in transient-transfection assays. Transcription start site analysis of HERV-MLV hybrid vectors revealed preferential use of the HERV promoter initiation site. Our data show that HERV LTRs function in the context of retroviral vectors in certain cell types and have the potential to be useful as cell type-specific promoters in vector construction.
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21
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Carré-Eusèbe D, Coudouel N, Magre S. OVEX1, a novel chicken endogenous retrovirus with sex-specific and left-right asymmetrical expression in gonads. Retrovirology 2009; 6:59. [PMID: 19534790 PMCID: PMC2717909 DOI: 10.1186/1742-4690-6-59] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2009] [Accepted: 06/17/2009] [Indexed: 01/03/2023] Open
Abstract
BACKGROUND In chickens, as in most birds, female gonad morphogenesis is asymmetrical. Gonads appear first rather similarly, but only the left one undergoes full differentiation and gives rise to a functional ovary. The right gonad, in which the cortex does not develop, remains restricted to the medulla and finally regresses. Opportunity was taken of this left-right asymmetry to perform a suppression subtractive hybridization screening to select for transcripts preferentially expressed in the developing left ovary as compared to the right one, and thus identify genes that are potentially involved in the process of ovarian differentiation. RESULTS One of these transcripts, named Ovex1 according to its expression profile, corresponds to an endogenous retrovirus that has not been previously characterized. It is transcribed as full-length and singly spliced mRNAs and contains three uninterrupted open reading frames coding potentially for proteins with homology to Gag and Pro-Pol retroviral polyproteins and a third protein showing only a weak similarity with Env glycoproteins. Ovex1 is severely degenerated; it is devoid of typical long terminal repeats and displays some evidence of recombination. An orthologous Ovex1 locus was identified in the genome of zebra finch, a member of a different bird order, and similar sequences were detected in turkey, guinea fowl, and duck DNA. The relationship between these sequences follows the bird phylogeny, suggesting vertical transmission of the endogenous retrovirus for more than 100 million years. Ovex1 is transcribed in chicken gonads with a sex-dependent and left-right asymmetrical pattern. It is first expressed in the cortex of the left indifferent gonads of both sexes. Expression is transient in the left testis and absent in the right one. In developing ovaries, Ovex1 transcription increases sharply in the left cortex and is weakly detected in the medulla. After folliculogenesis, Ovex1-expressing cells constitute the follicular granulosa cell layer. Ovex1 expression highlights a striking desquamation process that leads to profound cortical remodeling associated with follicle morphogenesis. CONCLUSION Evidence for a selection pressure at the protein level suggests that this endogenous retrovirus, expressed in the ovarian supporting cell lineage, might play an active role in bird ovarian physiology.
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Affiliation(s)
- Danièle Carré-Eusèbe
- Endocrinologie et Génétique de la Reproduction et du Développement, INSERM, U782, 32 rue des Carnets, F-92140, Clamart – France
- Univ. Paris-Sud, UMR-S0782, Clamart, F-92140
| | - Noëlline Coudouel
- Physiologie de l'Axe Gonadotrope, Unité de Biologie Fonctionnelle et Adaptative (BFA), Univ. PARIS 7 – CNRS, 4 rue MA Lagroua Weill-Hallé, 75205 Paris CEDEX 13 – France
| | - Solange Magre
- Physiologie de l'Axe Gonadotrope, Unité de Biologie Fonctionnelle et Adaptative (BFA), Univ. PARIS 7 – CNRS, 4 rue MA Lagroua Weill-Hallé, 75205 Paris CEDEX 13 – France
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22
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Abstract
Infection of germline cells with retroviruses initiates permanent proviral colonization of the germline genome. The germline-integrated proviruses, called endogenous retroviruses (ERVs), are inherited to offspring in a Mendelian order and belong to the transposable element family. Endogenous retroviruses and other long terminal repeat retroelements constitute ~8% and ~10% of the human and mouse genomes, respectively. It is likely that each individual has a distinct genomic ERV profile. Recent studies have revealed that a substantial fraction of ERVs retains the coding potentials necessary for virion assembly and replication. There are several layers of potential mechanisms controlling ERV expression: intracellular transcription environment (e.g., transcription factor pool, splicing machinery, hormones), epigenetic status of the genome (e.g., proviral methylation, histone acetylation), profile of transcription regulatory elements on each ERV's promoter, and a range of stress signals (e.g., injury, infection, environment). Endogenous retroviruses may exert pathophysiologic effects by infection followed by random reintegration into the genome, by their gene products (e.g., envelope, superantigen), and by altering the expression of neighboring genes. Several studies have provided evidence that ERVs are associated with a range of pathogenic processes involving multiple sclerosis, systemic lupus erythematosus, breast cancer, and the response to burn injury. For instance, the proinflammatory properties of the human ERV-W envelope protein play a central role in demyelination of oligodendrocytes. As reviewed in this article, recent advances in ERV biology and mammalian genomics suggest that ERVs may have a profound influence on various pathogenic processes including the response to injury and infection. Understanding the roles of ERVs in the pathogenesis of injury and infection will broaden insights into the underlying mechanisms of systemic immune disorder and organ failure in these patients.
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23
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Voisset C, Weiss RA, Griffiths DJ. Human RNA "rumor" viruses: the search for novel human retroviruses in chronic disease. Microbiol Mol Biol Rev 2008; 72:157-96, table of contents. [PMID: 18322038 PMCID: PMC2268285 DOI: 10.1128/mmbr.00033-07] [Citation(s) in RCA: 119] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Retroviruses are an important group of pathogens that cause a variety of diseases in humans and animals. Four human retroviruses are currently known, including human immunodeficiency virus type 1, which causes AIDS, and human T-lymphotropic virus type 1, which causes cancer and inflammatory disease. For many years, there have been sporadic reports of additional human retroviral infections, particularly in cancer and other chronic diseases. Unfortunately, many of these putative viruses remain unproven and controversial, and some retrovirologists have dismissed them as merely "human rumor viruses." Work in this field was last reviewed in depth in 1984, and since then, the molecular techniques available for identifying and characterizing retroviruses have improved enormously in sensitivity. The advent of PCR in particular has dramatically enhanced our ability to detect novel viral sequences in human tissues. However, DNA amplification techniques have also increased the potential for false-positive detection due to contamination. In addition, the presence of many families of human endogenous retroviruses (HERVs) within our DNA can obstruct attempts to identify and validate novel human retroviruses. Here, we aim to bring together the data on "novel" retroviral infections in humans by critically examining the evidence for those putative viruses that have been linked with disease and the likelihood that they represent genuine human infections. We provide a background to the field and a discussion of potential confounding factors along with some technical guidelines. In addition, some of the difficulties associated with obtaining formal proof of causation for common or ubiquitous agents such as HERVs are discussed.
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Affiliation(s)
- Cécile Voisset
- CNRS-UMR8161, Institut de Biologie de Lille et Institut Pasteur de Lille, Lille, France
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24
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The GLN family of murine endogenous retroviruses contains an element competent for infectious viral particle formation. J Virol 2008; 82:4413-9. [PMID: 18287236 DOI: 10.1128/jvi.02141-07] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Several families of endogenous retroviruses (ERVs) have been identified in the mouse genome, in several instances by in silico searches, but for many of them it remains to be determined whether there are elements that can still encode functional retroviral particles. Here, we identify, within the GLN family of highly reiterated ERVs, one, and only one, copy that encodes retroviral particles prone to infection of mouse cells. We show that its envelope protein confers an ecotropic host range and recognizes a receptor different from mCAT1 and mSMIT1, the two previously identified receptors for other ecotropic mouse retroviruses. Electron microscopy disclosed viral particle assembly and budding at the cell membrane, as well as release of mature particles into the extracellular space. These particles are closely related to murine leukemia virus (MLV) particles, with which they have most probably been confused in the past. This study, therefore, identifies a new class of infectious mouse ERVs belonging to the family Gammaretroviridae, with one family member still functional today. This family is in addition to the two MLV and mouse mammary tumor virus families of active mouse ERVs with an extracellular life cycle.
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25
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Murine endogenous retrovirus MuERV-L is the progenitor of the "orphan" epsilon viruslike particles of the early mouse embryo. J Virol 2007; 82:1622-5. [PMID: 18045933 DOI: 10.1128/jvi.02097-07] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Viruslike particles which displayed a peculiar wheellike appearance that distinguished them from A-, B- or C-type particles had previously been described in the early mouse embryo. The maximum expression of these so-called epsilon particles was observed in two-cell-stage embryos, followed by their rapid decline at later stages of development and no particles detected at the zygote one-cell stage. Here, we show that these particles are in fact produced by a newly discovered murine endogenous retrovirus (ERV) belonging to the widespread family of mammalian ERV-L elements and named MuERV-L. Using antibodies that we raised against the Gag protein of these elements, Western blot analysis and in toto immunofluorescence studies of the embryos at various stages disclosed the same developmental expression profile as that observed for epsilon particles. Using expression vectors for cloned, full-length, entirely coding MuERV-L copies and cell transfection, direct identification of the epsilon particles was finally achieved by high-resolution electron microscopy.
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26
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Riccioni C, Rubini A, Belfiori B, Passeri V, Paolocci F, Arcioni S. Tmt1: the first LTR-retrotransposon from a Tuber spp. Curr Genet 2007; 53:23-34. [PMID: 17972080 DOI: 10.1007/s00294-007-0155-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2007] [Revised: 09/03/2007] [Accepted: 09/13/2007] [Indexed: 10/22/2022]
Abstract
Retrotransposons are suitable targets for developing molecular markers for population genetics studies. Transposable elements have not yet been isolated from ectomycorrhizal fungi of the genus Tuber. In this paper, we report on the isolation and characterization of Tmt1, an LTR-retrotransposon from Tuber melanosporum. The Tmt1 sequence shows relatedness to Ty3/gypsy retrotransposons from which it differentiates for the presence of a dUTPase extra-domain between protease and reverse transcriptase. Phylogenetic analyses suggest a horizontal transfer of the dUTPase gene (dut) from a fungal host genome. The presence of non-identical LTRs and degenerate ORFs substantiate an ancient integration of Tmt1 in T. melanosporum genome. Furthermore, transcripts analyses proved an inactive status of Tmt1, whereas Southern analysis showed that Tmt1 is a repetitive T. melanosporum species-specific element. Tmt1-based markers will help us to gain more insights into population biology in this fungal species.
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Affiliation(s)
- Claudia Riccioni
- National Research Council, Plant Genetics Institute-Perugia, Perugia Division, Via Madonna Alta 130, 06128 Perugia, Italy
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27
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van de Lagemaat LN, Medstrand P, Mager DL. Multiple effects govern endogenous retrovirus survival patterns in human gene introns. Genome Biol 2007; 7:R86. [PMID: 17005047 PMCID: PMC1794541 DOI: 10.1186/gb-2006-7-9-r86] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2006] [Revised: 08/25/2006] [Accepted: 09/27/2006] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Endogenous retroviruses (ERVs) and solitary long terminal repeats (LTRs) have a significant antisense bias when located in gene introns, suggesting strong negative selective pressure on such elements oriented in the same transcriptional direction as the enclosing gene. It has been assumed that this bias reflects the presence of strong transcriptional regulatory signals within LTRs but little work has been done to investigate this phenomenon further. RESULTS In the analysis reported here, we found significant differences between individual human ERV families in their prevalence within genes and degree of antisense bias and show that, regardless of orientation, ERVs of most families are less likely to be found in introns than in intergenic regions. Examination of density profiles of ERVs across transcriptional units and the transcription signals present in the consensus ERVs suggests the importance of splice acceptor sites, in conjunction with splice donor and polyadenylation signals, as the major targets for selection against most families of ERVs/LTRs. Furthermore, analysis of annotated human mRNA splicing events involving ERV sequence revealed that the relatively young human ERVs (HERVs), HERV9 and HERV-K (HML-2), are involved in no human mRNA splicing events at all when oriented antisense to gene transcription, while elements in the sense direction in transcribed regions show considerable bias for use of strong splice sites. CONCLUSION Our observations suggest suppression of splicing among young intronic ERVs oriented antisense to gene transcription, which may account for their reduced mutagenicity and higher fixation rate in gene introns.
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Affiliation(s)
- Louie N van de Lagemaat
- Terry Fox Laboratory, BC Cancer Research Centre, 675 W 10th Avenue, Vancouver, BC, V5Z 1L3, Canada
- Department of Medical Genetics, University of British Columbia, BC, V6T 1Z3 Canada
| | - Patrik Medstrand
- Department of Experimental Medical Sciences, Lund University, BMC B13, 221 84 Lund, Sweden
| | - Dixie L Mager
- Terry Fox Laboratory, BC Cancer Research Centre, 675 W 10th Avenue, Vancouver, BC, V5Z 1L3, Canada
- Department of Medical Genetics, University of British Columbia, BC, V6T 1Z3 Canada
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28
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Nisole S, Stoye JP, Saïb A. TRIM family proteins: retroviral restriction and antiviral defence. Nat Rev Microbiol 2005; 3:799-808. [PMID: 16175175 DOI: 10.1038/nrmicro1248] [Citation(s) in RCA: 576] [Impact Index Per Article: 30.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Members of the tripartite motif (TRIM) protein family are involved in various cellular processes, including cell proliferation, differentiation, development, oncogenesis and apoptosis. Some TRIM proteins display antiviral properties, targeting retroviruses in particular. The potential activity of TRIM19, better known as promyelocytic leukaemia protein, against several viruses has been well documented and, recently, TRIM5alpha has been identified as the factor responsible for the previously described Lv1 and Ref1 antiretroviral activities. There is also evidence indicating that other TRIM proteins can influence viral replication. These findings are reviewed here, and the possibility that TRIMs represent a new and widespread class of antiviral proteins involved in innate immunity is also considered.
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Affiliation(s)
- Sébastien Nisole
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7151, Université Paris 7, Hôpital Saint-Louis, 1 Avenue Claude Vellefaux, 75475 Paris cedex 10, France.
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29
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Abstract
Host cellular genes can have profound effects on retrovirus replication. Many of these genes encode restriction factors that block virus infection; others encode positive factors that are exploited by the viruses. Recently, a number of such genes have been cloned and characterized, bringing into sharper focus the mechanisms and pathways exploited by these viruses. The major host factors involved in the early phase of the viral life cycle are discussed.
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Affiliation(s)
- Stephen P Goff
- Department of Biochemistry and Molecular Biophysics, Howard Hughes Medical Institute, Columbia University, New York, NY 10032, USA.
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30
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Rote NS, Chakrabarti S, Stetzer BP. The role of human endogenous retroviruses in trophoblast differentiation and placental development. Placenta 2005; 25:673-83. [PMID: 15450384 DOI: 10.1016/j.placenta.2004.02.008] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 02/13/2004] [Indexed: 11/29/2022]
Abstract
A major portion of the human genome appears to be of retroviral origin. These endogenous retroviral elements are expressed in a variety of normal tissues and during disease states, such as autoimmune and malignant conditions. Recently, potential roles have been described for endogenous retroviral envelope proteins in normal differentiation of human villous cytotrophoblast into syncytiotrophoblast. This article provides a brief critical review of the current state of knowledge concerning the expression of the env regions of three endogenous retroviral elements: ERV-3, HERV-W, and HERV-FRD. A testable model of villous cytotrophoblast differentiation is constructed, in which a complementary expression of endogenous retroviral envelope proteins initiates hCG production, decreased cell proliferation, and intercellular fusion.
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Affiliation(s)
- N S Rote
- Department of Obstetrics and Gynecology, MetroHealth Medical Center, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA.
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31
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Sequence and comparative analysis of the chicken genome provide unique perspectives on vertebrate evolution. Nature 2004; 432:695-716. [PMID: 15592404 DOI: 10.1038/nature03154] [Citation(s) in RCA: 1960] [Impact Index Per Article: 98.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2004] [Accepted: 11/01/2004] [Indexed: 12/28/2022]
Abstract
We present here a draft genome sequence of the red jungle fowl, Gallus gallus. Because the chicken is a modern descendant of the dinosaurs and the first non-mammalian amniote to have its genome sequenced, the draft sequence of its genome--composed of approximately one billion base pairs of sequence and an estimated 20,000-23,000 genes--provides a new perspective on vertebrate genome evolution, while also improving the annotation of mammalian genomes. For example, the evolutionary distance between chicken and human provides high specificity in detecting functional elements, both non-coding and coding. Notably, many conserved non-coding sequences are far from genes and cannot be assigned to defined functional classes. In coding regions the evolutionary dynamics of protein domains and orthologous groups illustrate processes that distinguish the lineages leading to birds and mammals. The distinctive properties of avian microchromosomes, together with the inferred patterns of conserved synteny, provide additional insights into vertebrate chromosome architecture.
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Yi JM, Kim TH, Huh JW, Park KS, Jang SB, Kim HM, Kim HS. Human endogenous retroviral elements belonging to the HERV-S family from human tissues, cancer cells, and primates: expression, structure, phylogeny and evolution. Gene 2004; 342:283-92. [PMID: 15527987 DOI: 10.1016/j.gene.2004.08.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2004] [Revised: 07/28/2004] [Accepted: 08/12/2004] [Indexed: 11/21/2022]
Abstract
A new human endogenous retrovirus family (HERV-S) was recently identified from the human chromosome X. The HERV-S was 6.7 kb in length with typical retroviral structure (LTR-gag-pol-env-LTR). We investigated pol fragments of HERV-S family in various human tissues and cancer cells. The pol gene was expressed in only brain and thymus among human tissues (brain, prostate, testis, heart, kidney, liver, lung, placenta, skeletal muscle, spleen, thymus, uterus), whereas the pol gene was detected in various cancer cell lines (RT4, PFSK-1, BT-474, HCT-116, Jurkat, HepG2, MCF7, OVCAR-3, MIA-PaCa-2, PC3, LOX-IMVI, AZ521, 2F7, and C-33A) except for TE-1, UO-31, A549, and U-937 by RT-PCR analysis. Expression and sequencing data of the 33 clones imply that the pol gene of HERV-S family is more active in cancer cells than in human tissues, which may have transcriptional potential role related to various human cancers. Phylogenetic analysis of HERV-S pol family distinctively divided into three groups (group I, II, and III) through evolutionary divergence in primate evolution. Evolutionary divergence of the HERV-S family by PCR amplification and sequence analysis indicated that they were integrated into the primate genomes approximately 43 Myr ago and have been evolved rate of 0.3% nucleotide differences per Myr during primate evolution.
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Affiliation(s)
- Joo-Mi Yi
- Division of Biological Sciences, College of Natural Sciences, Pusan National University, Pusan 609-735, Korea
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Mayer J, Meese EU. Presence of dUTPase in the various human endogenous retrovirus K (HERV-K) families. J Mol Evol 2004; 57:642-9. [PMID: 14745533 DOI: 10.1007/s00239-003-2514-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2003] [Accepted: 07/02/2003] [Indexed: 10/26/2022]
Abstract
Various retroviruses have been shown to encode dUTPase. The overall phylogeny of dUTPase is unclear, though. The human genome contains a significant amount of human endogenous retroviruses (HERV) representing fossilized sequences of ancient exogenous retroviruses. A few HERV families have been reported to harbor dUTPase domains. We surveyed the various HERV families for the presence of dUTPase and found that ancestors of all HERV-K families but one encoded dUTPase. With two exceptions phylogenetic analysis shows a monophyletic origin of dUTPase for the different HERV-K dUTPases. Sequences of consensus dUTPase domains suggest that the various exogenous ancestors of HERV-K once encoded active enzymes. Our analysis provides informations on dUTPase phylogeny and further shows that endogenous retroviruses provide important informations regarding retrovirus evolution.
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Affiliation(s)
- Jens Mayer
- Human Genetics, Building 60, University of Saar, Medical Faculty, 66421 Homburg, Germany.
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Selvatici R, Melloni E, Ferrati M, Piubello C, Marincola FC, Gandini E. Adaptative value of a PKC-PKI55 feedback loop of inhibition that prevents the kinase's deregulation. J Mol Evol 2004; 57:131-9. [PMID: 14562957 DOI: 10.1007/s00239-003-2457-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2002] [Accepted: 02/12/2003] [Indexed: 11/27/2022]
Abstract
A 168-bp amplification product was obtained in RT-PCR experiments using a degenerate oligonucleotide designed on a five-amino acid sequence of IN, a 7-kDa protein, previously characterized as a PKC inhibitor. It was included in the coding ORF of the 1530-bp-long IMAGE clone ID 38900 (accession numbers R51337 and R51448) that produces a translation product of 6.5 kDa. The translation of the ORF conceptual reading frame allowed the preparation of the synthetic protein PKI55, which was found to inhibit and degrade both untreated nPKC d isozymes and activated cPKC isozymes. The PKI55 gene is localized in chromosome 2q35. The Repeat Maskers output showed a 533-bp-long LTR32/ERVL segment that included the PKI55 coding sequence and a complete regulatory region. The coding sequence and the structure of PKI55 were detected in a brain cDNA of Macaca fascicularis (diverged from human lineages about 25 Myr ago). Three other human genes with over 60% identities with PKI55 were identified in three different loci (i.e., chromosomes 10, 15, and 20.) Synthesis of PKI55 was stimulated by PKC activation. A feedback loop of inhibition is established. When the PKCs are overactivated, PKI55 induces degradation of the enzyme and prevents the isozyme overexpression implicated in a number of important diseases including cancer, diabetes, and disorders of the immune system. The presence of the PKI55 sequence in Macaca fascicularis as well as in human chromosomes 10, 15, and 20 indicates a selective advantage for the PKI55 sequence and the adaptive value of the feedback mechanism.
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Affiliation(s)
- Rita Selvatici
- Department of Experimental and Diagnostic Medicine, Section of Medical Genetics, University of Ferrara, Via L. Borsari 46, 44100 Ferrara, Italy
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Dunn CA, Medstrand P, Mager DL. An endogenous retroviral long terminal repeat is the dominant promoter for human beta1,3-galactosyltransferase 5 in the colon. Proc Natl Acad Sci U S A 2003; 100:12841-6. [PMID: 14534330 PMCID: PMC240706 DOI: 10.1073/pnas.2134464100] [Citation(s) in RCA: 95] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
LTRs of endogenous retroviruses are known to affect expression of several human genes, typically as a relatively minor alternative promoter. Here, we report that an endogenous retrovirus LTR acts as one of at least two alternative promoters for the human beta1,3-galactosyltransferase 5 gene, involved in type 1 Lewis antigen synthesis, and show that the LTR promoter is most active in the gastrointestinal tract and mammary gland. Indeed, the LTR is the dominant promoter in the colon, indicating that this ancient retroviral element has a major impact on gene expression. Using colorectal cancer cell lines and electrophoretic mobility-shift assays, we found that hepatocyte nuclear factor 1 (HNF-1) binds a site within the retroviral promoter and that expression of HNF-1 and interaction with its binding site correlated with promoter activation. We conclude that HNF-1 is at least partially responsible for the tissue-specific activation of the LTR promoter of human beta 1,3-galactosyltransferase 5. We demonstrate that this tissue-specific transcription factor is implicated in the activation of an LTR gene promoter.
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Affiliation(s)
- Catherine A. Dunn
- Terry Fox Laboratory, BC Cancer Agency, Vancouver, BC, Canada V5Z 1L3; Department of Cell and Molecular Biology, Biomedical Centre, Lund University, 221 84 Lund, Sweden; and Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada V6T 1Z1
| | - Patrik Medstrand
- Terry Fox Laboratory, BC Cancer Agency, Vancouver, BC, Canada V5Z 1L3; Department of Cell and Molecular Biology, Biomedical Centre, Lund University, 221 84 Lund, Sweden; and Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada V6T 1Z1
| | - Dixie L. Mager
- Terry Fox Laboratory, BC Cancer Agency, Vancouver, BC, Canada V5Z 1L3; Department of Cell and Molecular Biology, Biomedical Centre, Lund University, 221 84 Lund, Sweden; and Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada V6T 1Z1
- To whom correspondence should be addressed. E-mail:
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Abstract
Virtually all nonhuman primate species investigated thus far including prosimians, New World and Old World monkeys and apes all harbor distinct and species-specific clades of simian foamy virus (SFV). However, evidence supporting the existence of a human-specific foamy virus (FV) is not yet available. Early reports describing widespread infection of healthy and sick humans with FV could not be confirmed. In contrast, all FV infections documented in humans are of zoonotic origin and are identified in persons occupationally exposed to nonhuman primates. The introduction of SFV into humans raises several public health questions regarding disease outcomes and potential for human-to-human transmissibility. The available data from a very limited number of SFV-infected humans suggest that these infections are nonpathogenic and are not easily transmissible. Additional studies are needed to better define the prevalence and natural history of SFV in humans.
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Affiliation(s)
- W Heneine
- HIV and Retrovirology Branch, Centers for Disease Control and Prevention, 1600 Clifton Road, Mail Stop G19, Atlanta, GA 30333, USA.
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Bénit L, Calteau A, Heidmann T. Characterization of the low-copy HERV-Fc family: evidence for recent integrations in primates of elements with coding envelope genes. Virology 2003; 312:159-68. [PMID: 12890629 DOI: 10.1016/s0042-6822(03)00163-6] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
In a previous search based on the envelope gene, we had identified two related proviral elements that could not be included in identified ERV families. An in silico database screening associated with an in vivo polymerase chain reaction search using primers in the reverse transcriptase domain, now allowed identification of a series of related elements, found at a limited number in simians. A phylogenetic analysis led to their inclusion in a new family of endogenous retroviruses with limited expansion, which we named ERV-Fc, and which is part of the enlarged ERV-F/H family. The human genome comprises only six HERV-Fc, among which two possess full-length coding envelope genes. A complete provirus was identified in the baboon, also disclosing a fully open envelope gene. Cloning of the sites orthologous to the envelope-coding human proviruses demonstrated presence of the integrated proviruses in chimpanzee and gorilla, but not in orangutan. For the baboon element, the orthologous locus was found empty even in the phylogenetically most closely related macaque, again suggesting, together with the complete identity of its LTRs, "recent" integration. The data presented are compatible with an evolutionary scheme in which the ERV-Fc proviruses would be the endogenous traces of an active retroviral element, possibly acting as an infectious retrovirus with low endogeneization potency, with evidence for integrations at two distinct periods of primate evolution.
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Affiliation(s)
- Laurence Bénit
- Unité des Rétrovirus Endogènes et Eléments Rétroïdes des Eucaryotes Supérieurs, UMR 8122 CNRS, Institut Gustave Roussy, 39 rue Camille Desmoulins, 94805 Villejuif Cedex, France
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38
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Zhang Z, Gerstein M. The human genome has 49 cytochrome c pseudogenes, including a relic of a primordial gene that still functions in mouse. Gene 2003; 312:61-72. [PMID: 12909341 DOI: 10.1016/s0378-1119(03)00579-1] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Using a computational approach, we have identified 49 cytochrome c (cyc) pseudogenes in the human genome. Analysis of these provides a detailed description of the molecular evolution of the cyc gene. Almost all of the pseudogenes are full-length, and we have concluded that they mostly originated from independent retrotransposition events (i.e. they are processed). Based on phylogenetic analysis and detailed sequence comparison, we have further divided these pseudogenes into two groups. The first, consisting of four young pseudogenes that were dated to be between 27 and 34 Myr old, originated from a gene almost identical to the modern human cyc gene. The second group of pseudogenes is much older and appears to have descended from ancient genes similar to modern rodent cyc genes. Thus, our results support the observation that accelerated evolution in cyc sequence had occurred in the primate lineage. The oldest pseudogene in the second group, dated to be over 80 Myr old, resembles the testis-specific cyc gene in modern rodents. It is likely that the mammalian ancestor had both the somatic and the testis-specific cyc genes. While the testis-specific gene is still functional in modern rodents, the human has lost it, retaining only a pseudogene in its place. Thus, our study may have identified a pseudogene that is a dead relic of a gene that has completely died off in the human lineage.
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Affiliation(s)
- Zhaolei Zhang
- Department of Molecular Biophysics and Biochemistry, Yale University, 266 Whitney Avenue, New Haven, CT 06520-8114, USA
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39
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Kambol R, Kabat P, Tristem M. Complete nucleotide sequence of an endogenous retrovirus from the amphibian, Xenopus laevis. Virology 2003; 311:1-6. [PMID: 12832197 DOI: 10.1016/s0042-6822(03)00263-0] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
We report the first full-length sequence of an endogenous amphibian retrovirus derived from the African clawed toad Xenopus laevis. The virus, termed Xen1, has one of the largest endogenous retroviral genomes described to date of over 10 kb in length and it also has a relatively complex genomic organisation consisting of LTR-orf1, orf2, gag, pol, env-LTR. Orfs 1 and 2 are novel, duplicated genes of unknown function. Phylogenetic analysis indicates that Xen1 is most closely related to the epsilon -retroviruses WDSV and WEHV types 1 and 2, which are large, complex exogenous retroviruses present within Walleye fish.
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Affiliation(s)
- Roziah Kambol
- Department of Biological Sciences, Imperial College, Silwood Park, Buckhurst Road, SL5 7PY, Ascot, Berkshire, UK
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40
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Abstract
The retroviral capacity for integration into the host genome can give rise to endogenous retroviruses (ERVs): retroviral sequences that are transmitted vertically as part of the host germ line, within which they may continue to replicate and evolve. ERVs represent both a unique archive of ancient viral sequence information and a dynamic component of host genomes. As such they hold great potential as informative markers for studies of both virus evolution and host genome evolution. Numerous novel ERVs have been described in recent years, particularly as genome sequencing projects have advanced. This review discusses the evolution of ERV lineages, considering the processes by which ERV distribution and diversity is generated. The diversity of ERVs isolated so far is summarised in terms of both their distribution across host taxa, and their relationships to recognised retroviral genera. Finally the relevance of ERVs to studies of genome evolution, host disease and viral ecology is considered, and recent findings discussed.
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Affiliation(s)
- Robert Gifford
- Department of Biological Sciences, Imperial College, Silwood Park, Buckhurst Road, Ascot Berkshire, SL5 7PY, UK
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41
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Abstract
A substantial amount of the human genome is composed of human endogenous retroviruses (HERVs). Manifold HERV families have been identified, among them several so-called HERV-K(HML) families. Although the HERV-K(HML-2) family has been studied in detail, other HERV-K families are not as well characterized. We describe here the HERV-K HML-3 family in more detail. We estimate that there are about 140 proviral loci or remains of such per haploid genome. Most loci are severely mutated. Proviruses displaying larger deletions in gag and pol are common. A multiple alignment of 73 HERV-K(HML-3) sequences displays several potentially important differences compared with the HERVK9I sequence in Repbase. A consensus sequence with open reading frames for all retroviral genes was generated, for which intact dUTPase motifs and env gene variants with different coding capacities are observed. Phylogenetic analysis shows near-monophyly with distinction of two closely related subgroups. Proviruses formed about 36 million years ago. However, no continuous activity through primate evolution is indicated.
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Affiliation(s)
- Jens Mayer
- Human Genetics, Medical Faculty, University of Saar, Homburg, Germany.
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42
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Lander ES, Linton LM, Birren B, Nusbaum C, Zody MC, Baldwin J, Devon K, Dewar K, Doyle M, FitzHugh W, Funke R, Gage D, Harris K, Heaford A, Howland J, Kann L, Lehoczky J, LeVine R, McEwan P, McKernan K, Meldrim J, Mesirov JP, Miranda C, Morris W, Naylor J, Raymond C, Rosetti M, Santos R, Sheridan A, Sougnez C, Stange-Thomann Y, Stojanovic N, Subramanian A, Wyman D, Rogers J, Sulston J, Ainscough R, Beck S, Bentley D, Burton J, Clee C, Carter N, Coulson A, Deadman R, Deloukas P, Dunham A, Dunham I, Durbin R, French L, Grafham D, Gregory S, Hubbard T, Humphray S, Hunt A, Jones M, Lloyd C, McMurray A, Matthews L, Mercer S, Milne S, Mullikin JC, Mungall A, Plumb R, Ross M, Shownkeen R, Sims S, Waterston RH, Wilson RK, Hillier LW, McPherson JD, Marra MA, Mardis ER, Fulton LA, Chinwalla AT, Pepin KH, Gish WR, Chissoe SL, Wendl MC, Delehaunty KD, Miner TL, Delehaunty A, Kramer JB, Cook LL, Fulton RS, Johnson DL, Minx PJ, Clifton SW, Hawkins T, Branscomb E, Predki P, Richardson P, Wenning S, Slezak T, Doggett N, Cheng JF, Olsen A, Lucas S, Elkin C, Uberbacher E, Frazier M, Gibbs RA, Muzny DM, Scherer SE, Bouck JB, Sodergren EJ, Worley KC, Rives CM, Gorrell JH, Metzker ML, Naylor SL, Kucherlapati RS, Nelson DL, Weinstock GM, Sakaki Y, Fujiyama A, Hattori M, Yada T, Toyoda A, Itoh T, Kawagoe C, Watanabe H, Totoki Y, Taylor T, Weissenbach J, Heilig R, Saurin W, Artiguenave F, Brottier P, Bruls T, Pelletier E, Robert C, Wincker P, Smith DR, Doucette-Stamm L, Rubenfield M, Weinstock K, Lee HM, Dubois J, Rosenthal A, Platzer M, Nyakatura G, Taudien S, Rump A, Yang H, Yu J, Wang J, Huang G, Gu J, Hood L, Rowen L, Madan A, Qin S, Davis RW, Federspiel NA, Abola AP, Proctor MJ, Myers RM, Schmutz J, Dickson M, Grimwood J, Cox DR, Olson MV, Kaul R, Raymond C, Shimizu N, Kawasaki K, Minoshima S, Evans GA, Athanasiou M, Schultz R, Roe BA, Chen F, Pan H, Ramser J, Lehrach H, Reinhardt R, McCombie WR, de la Bastide M, Dedhia N, Blöcker H, Hornischer K, Nordsiek G, Agarwala R, Aravind L, Bailey JA, Bateman A, Batzoglou S, Birney E, Bork P, Brown DG, Burge CB, Cerutti L, Chen HC, Church D, Clamp M, Copley RR, Doerks T, Eddy SR, Eichler EE, Furey TS, Galagan J, Gilbert JG, Harmon C, Hayashizaki Y, Haussler D, Hermjakob H, Hokamp K, Jang W, Johnson LS, Jones TA, Kasif S, Kaspryzk A, Kennedy S, Kent WJ, Kitts P, Koonin EV, Korf I, Kulp D, Lancet D, Lowe TM, McLysaght A, Mikkelsen T, Moran JV, Mulder N, Pollara VJ, Ponting CP, Schuler G, Schultz J, Slater G, Smit AF, Stupka E, Szustakowki J, Thierry-Mieg D, Thierry-Mieg J, Wagner L, Wallis J, Wheeler R, Williams A, Wolf YI, Wolfe KH, Yang SP, Yeh RF, Collins F, Guyer MS, Peterson J, Felsenfeld A, Wetterstrand KA, Patrinos A, Morgan MJ, de Jong P, Catanese JJ, Osoegawa K, Shizuya H, Choi S, Chen YJ, Szustakowki J. Initial sequencing and analysis of the human genome. Nature 2001; 409:860-921. [PMID: 11237011 DOI: 10.1038/35057062] [Citation(s) in RCA: 14617] [Impact Index Per Article: 635.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The human genome holds an extraordinary trove of information about human development, physiology, medicine and evolution. Here we report the results of an international collaboration to produce and make freely available a draft sequence of the human genome. We also present an initial analysis of the data, describing some of the insights that can be gleaned from the sequence.
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Affiliation(s)
- E S Lander
- Whitehead Institute for Biomedical Research, Center for Genome Research, Cambridge, MA 02142, USA.
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Schön U, Seifarth W, Baust C, Hohenadl C, Erfle V, Leib-Mösch C. Cell type-specific expression and promoter activity of human endogenous retroviral long terminal repeats. Virology 2001; 279:280-91. [PMID: 11145909 DOI: 10.1006/viro.2000.0712] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Evolution over millions of years has adapted several thousand copies of retrovirus-like elements and over 10 times as many solitary long terminal repeats (LTRs) to their present location in the human genome. Transcription of these human endogenous retroviruses (HERVs) has been detected in various cells and tissues, and in some cases their transcriptional control elements have been recruited by cellular genes. We used a retroviral pol-specific expression array to obtain a HERV transcription profile in a variety of human cells such as epidermal keratinocytes, liver cells, kidney cells, pancreatic cells, lymphocytes, and lung fibroblasts. This rapid screening test revealed a distinct HERV pol-expression pattern in each cell type tested so far. About 40 different U3/R regulatory sequences from the HERV-H and HERV-W families were then amplified from actively transcribed 3'HERV LTRs of various cell lines and tissues. Their promoter activities were compared with LTR sequences of other known HERV families in 12 human cell lines using a transient luciferase reporter system. Expression of the isolated HERV LTRs varied significantly in these cell lines, in some cases showing strict cell type specificity. These results suggest that endogenous retroviral LTRs may be a valuable source of transcriptional regulatory elements for the construction of targeted retroviral expression vectors.
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Affiliation(s)
- U Schön
- Institute of Molecular Virology, Oberschleissheim, D-85764, Germany.
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44
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Abstract
Foamy viruses (FV) are complex retroviruses which are widespread in many species. Despite being discovered over 40 years ago, FV are among the least well characterized retroviruses. The replication of these viruses is different in many interesting respects from that of all other retroviruses. Infection of natural hosts by FV leads to a lifelong persistent infection, without any evidence of pathology. A large number of studies have looked at the prevalence of primate foamy viruses in the human population. Many of these studies have suggested that FV infections are prevalent in some human populations and are associated with specific diseases. More recent data, using more rigorous criteria for the presence of viruses, have not confirmed these studies. Thus, while FV are ubiquitous in all nonhuman primates, they are only acquired as rare zoonotic infections in humans. In this communication, we briefly discuss the current status of FV research and review the history of FV epidemiology, as well as the lack of pathogenicity in natural, experimental, and zoonotic infections.
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Affiliation(s)
- C D Meiering
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA
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45
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Towers G, Bock M, Martin S, Takeuchi Y, Stoye JP, Danos O. A conserved mechanism of retrovirus restriction in mammals. Proc Natl Acad Sci U S A 2000; 97:12295-9. [PMID: 11027299 PMCID: PMC17335 DOI: 10.1073/pnas.200286297] [Citation(s) in RCA: 207] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The murine Fv1 gene restricts infection by N- or B-tropic murine leukemia viruses at a postentry, preintegration stage. The Fv1-sensitive viruses previously used for the study of Fv1 encode an ecotropic envelope gene and thus only infect rodent cells. Consequently, the study of Fv1 restriction has been carried out solely in mice and murine cell lines. By infection with retroviral vectors containing N- or B-tropic core and pantropic vesicular stomatitis virus-G envelope protein, we now demonstrate that cell lines derived from various mammalian species, including humans, have an Fv1-like retrovirus restriction function, preventing N-tropic vector infection. Like Fv1, restriction is directed at amino acid 110 of the viral capsid protein. In contrast to Fv1, the novel restriction is characterized by the absence of reverse-transcribed viral DNA. We speculate that these activities have been selected for by retroviral epidemics in the distant past.
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Affiliation(s)
- G Towers
- Wohl Virion Centre, Windeyer Institute of Medical Sciences, University College London, 46 Cleveland Street, London W1P 6DB, United Kingdom
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Tristem M. Identification and characterization of novel human endogenous retrovirus families by phylogenetic screening of the human genome mapping project database. J Virol 2000; 74:3715-30. [PMID: 10729147 PMCID: PMC111881 DOI: 10.1128/jvi.74.8.3715-3730.2000] [Citation(s) in RCA: 231] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Human endogenous retroviruses (HERVs) were first identified almost 20 years ago, and since then numerous families have been described. It has, however, been difficult to obtain a good estimate of both the total number of independently derived families and their relationship to each other as well as to other members of the family Retroviridae. In this study, I used sequence data derived from over 150 novel HERVs, obtained from the Human Genome Mapping Project database, and a variety of recently identified nonhuman retroviruses to classify the HERVs into 22 independently acquired families. Of these, 17 families were loosely assigned to the class I HERVs, 3 to the class II HERVs and 2 to the class III HERVs. Many of these families have been identified previously, but six are described here for the first time and another four, for which only partial sequence information was previously available, were further characterized. Members of each of the 10 families are defective, and calculation of their integration dates suggested that most of them are likely to have been present within the human lineage since it diverged from the Old World monkeys more than 25 million years ago.
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Affiliation(s)
- M Tristem
- Department of Biology, Imperial College, Silwood Park, Ascot, Berkshire SL5 7PY, United Kingdom.
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Khier H, Bartl S, Schuettengruber B, Seiser C. Molecular cloning and characterization of the mouse histone deacetylase 1 gene: integration of a retrovirus in 129SV mice. BIOCHIMICA ET BIOPHYSICA ACTA 1999; 1489:365-73. [PMID: 10673037 DOI: 10.1016/s0167-4781(99)00203-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Reversible histone acetylation plays an important role for chromatin structure and gene expression. The acetylation state of core histones is controlled by histone acetyltransferases and histone deacetylases. Here we report the cloning and characterization of the mouse histone deacetylase 1 (HDAC1) gene. The mouse genome contains several HDAC1-related structures representing the HDAC1 gene and at least three pseudogenes. The HDAC1 gene comprises 14 exons ranging from 49 to 539 bp. Interestingly the murine HDAC1 gene strongly resembles the previously published mouse HDAC2 gene (Zeng et al., J. Biol. Chem. 273 (1998) 28921-28930). The sizes of ten of the 14 exons are identical for both genes and the splicing sites for 11 introns align in identical positions suggesting a gene duplication event. The HDAC1 gene is located only 128 bp downstream from the MARCKS-related protein (MRP) gene in a tail-to-tail orientation. The murine MRP gene was previously mapped to a conserved gene cluster on chromosome 4 sharing linkage homology to human chromosome 1p32-36. The genes for HDAC1 and MRP are co-expressed in a variety of cell types. In the genome of 129SV mice the largest intervening sequence of the HDAC1 gene, intron 3, harbors a complete copy of the endogenous retrovirus MuERV-L. In contrast the HDAC1 gene in other mouse strains such as C57B16, C3H/An and C-RY lacks the retrovirus. Our study provides useful tools for future targeted gene disruption studies.
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Affiliation(s)
- H Khier
- Institute of Molecular Biology, Vienna Biocenter, University of Vienna, Austria
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Voisset C, Blancher A, Perron H, Mandrand B, Mallet F, Paranhos-Baccalà G. Phylogeny of a novel family of human endogenous retrovirus sequences, HERV-W, in humans and other primates. AIDS Res Hum Retroviruses 1999; 15:1529-33. [PMID: 10580403 DOI: 10.1089/088922299309810] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
A novel human endogenous retrovirus, HERV-W, has been characterized on the basis of multiple sclerosis-associated retrovirus (MSRV) probes. We have analyzed the phylogenetic distribution of HERV-W in humans and other primate species. As HERV-W presents a C/D chimeric nature and is largely composed of deleted elements, Southern blots were performed using gag, pol, env, and LTR probes. The relative complexities observed for gag, pol, env, and LTR regions were similar in humans, apes, and Old World monkeys, the minimal number of bands observed after Southern blot analysis being 25, 50, 10, and at least 100, respectively. The HERV-W family entered the genome of catarrhines more than 25 million years ago.
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Affiliation(s)
- C Voisset
- Unité Mixte de Recherche 103 CNRS-bioMérieux, Ecole Normale Supérieure de Lyon, France
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49
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Baldo AM, McClure MA. Evolution and horizontal transfer of dUTPase-encoding genes in viruses and their hosts. J Virol 1999; 73:7710-21. [PMID: 10438861 PMCID: PMC104298 DOI: 10.1128/jvi.73.9.7710-7721.1999] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
dUTPase is a ubiquitous and essential enzyme responsible for regulating cellular levels of dUTP. The dut gene exists as single, tandemly duplicated, and tandemly triplicated copies. Crystallized single-copy dUTPases have been shown to assemble as homotrimers. dUTPase is encoded as an auxiliary gene in a number of virus genomes. The origin of viral dut genes has remained unresolved since their initial discovery. A comprehensive analysis of dUTPase amino acid sequence relationships was performed to explore the evolutionary dynamics of dut in viruses and their hosts. Our data set, comprised of 24 host and 51 viral sequences, includes representative sequences from available eukaryotes, archaea, eubacteria cells, and viruses, including herpesviruses. These amino acid sequences were aligned by using a hidden Markov model approach developed to align divergent data. Known secondary structures from single-copy crystals were mapped onto the aligned duplicate and triplicate sequences. We show how duplicated dUTPases might fold into a monomer, and we hypothesize that triplicated dUTPases also assemble as monomers. Phylogenetic analysis revealed at least five viral dUTPase sequence lineages in well-supported monophyletic clusters with eukaryotic, eubacterial, and archaeal hosts. We have identified all five as strong examples of horizontal transfer as well as additional potential transfer of dut genes among eubacteria, between eubacteria and viruses, and between retroviruses. The evidence for horizontal transfers is particularly interesting since eukaryotic dut genes have introns, while DNA virus dut genes do not. This implies that an intermediary retroid agent facilitated the horizontal transfer process between host mRNA and DNA viruses.
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Affiliation(s)
- A M Baldo
- Department of Biological Sciences, University of Nevada-Las Vegas, Las Vegas, Nevada 89154-4004, USA
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Bénit L, Lallemand JB, Casella JF, Philippe H, Heidmann T. ERV-L elements: a family of endogenous retrovirus-like elements active throughout the evolution of mammals. J Virol 1999; 73:3301-8. [PMID: 10074184 PMCID: PMC104094 DOI: 10.1128/jvi.73.4.3301-3308.1999] [Citation(s) in RCA: 107] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We have previously identified in the human genome a family of 200 endogenous retrovirus-like elements, the HERV-L elements, disclosing similarities with the foamy retroviruses and which might be the evolutionary intermediate between classical intracellular retrotransposons and infectious retroviruses. Southern blot analysis of a large series of mammalian genomic DNAs shows that HERV-L-related elements-so-called ERV-L-are present among all placental mammals, suggesting that ERV-L elements were already present at least 70 million years ago. Most species exhibit a low copy number of ERV-L elements (from 10 to 30), while simians (not prosimians) and mice (not rats) have been subjected to bursts resulting in increases in the number of copies up to 200. The burst of copy number in primates can be dated to shortly after the prosimian and simian branchpoint, 45 to 65 million years ago, whereas murine species have been subjected to two much more recent bursts (less than 10 million years ago), occurring after the Mus/Rattus split. We have amplified and sequenced 360-bp ERV-L internal fragments of the highly conserved pol gene from a series of 22 mammalian species. These sequences exhibit high percentages of identity (57 to 99%) with the murine fully coding MuERV-L element. Phylogenetic analyses allowed the establishment of a plausible evolutionary scheme for ERV-L elements, which accounts for the high level of sequence conservation and the widespread dispersion among mammals.
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Affiliation(s)
- L Bénit
- Unité des Rétrovirus Endogènes et Eléments Rétroïdes des Eucaryotes Supérieurs, CNRS UMR 1573, Institut Gustave Roussy, 94805 Villejuif, France
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