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Kitsou K, Katzourakis A, Magiorkinis G. Limitations of current high-throughput sequencing technologies lead to biased expression estimates of endogenous retroviral elements. NAR Genom Bioinform 2024; 6:lqae081. [PMID: 38984066 PMCID: PMC11231582 DOI: 10.1093/nargab/lqae081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2023] [Revised: 04/09/2024] [Accepted: 06/27/2024] [Indexed: 07/11/2024] Open
Abstract
Human endogenous retroviruses (HERVs), the remnants of ancient germline retroviral integrations, comprise almost 8% of the human genome. The elucidation of their biological roles is hampered by our inability to link HERV mRNA and protein production with specific HERV loci. To solve the riddle of the integration-specific RNA expression of HERVs, several bioinformatics approaches have been proposed; however, no single process seems to yield optimal results due to the repetitiveness of HERV integrations. The performance of existing data-bioinformatics pipelines has been evaluated against real world datasets whose true expression profile is unknown, thus the accuracy of widely-used approaches remains unclear. Here, we simulated mRNA production from specific HERV integrations to evaluate second and third generation sequencing technologies along with widely used bioinformatic approaches to estimate the accuracy in describing integration-specific expression. We demonstrate that, while a HERV-family approach offers accurate results, per-integration analyses of HERV expression suffer from substantial expression bias, which is only partially mitigated by algorithms developed for calculating the per-integration HERV expression, and is more pronounced in recent integrations. Hence, this bias could erroneously result into biologically meaningful inferences. Finally, we demonstrate the merits of accurate long-read high-throughput sequencing technologies in the resolution of per-locus HERV expression.
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Affiliation(s)
- Konstantina Kitsou
- Department of Hygiene, Epidemiology and Medical Statistics, National and Kapodistrian University of Athens, Athens 11527, Greece
| | | | - Gkikas Magiorkinis
- Department of Hygiene, Epidemiology and Medical Statistics, National and Kapodistrian University of Athens, Athens 11527, Greece
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2
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Li C, Qian Q, Yan C, Lu M, Li L, Li P, Fan Z, Lei W, Shang K, Wang P, Wang J, Lu T, Huang Y, Yang H, Wei H, Han J, Xiao J, Chen F. HervD Atlas: a curated knowledgebase of associations between human endogenous retroviruses and diseases. Nucleic Acids Res 2024; 52:D1315-D1326. [PMID: 37870452 PMCID: PMC10767980 DOI: 10.1093/nar/gkad904] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Revised: 10/03/2023] [Accepted: 10/06/2023] [Indexed: 10/24/2023] Open
Abstract
Human endogenous retroviruses (HERVs), as remnants of ancient exogenous retrovirus infected and integrated into germ cells, comprise ∼8% of the human genome. These HERVs have been implicated in numerous diseases, and extensive research has been conducted to uncover their specific roles. Despite these efforts, a comprehensive source of HERV-disease association still needs to be added. To address this gap, we introduce the HervD Atlas (https://ngdc.cncb.ac.cn/hervd/), an integrated knowledgebase of HERV-disease associations manually curated from all related published literature. In the current version, HervD Atlas collects 60 726 HERV-disease associations from 254 publications (out of 4692 screened literature), covering 21 790 HERVs (21 049 HERV-Terms and 741 HERV-Elements) belonging to six types, 149 diseases and 610 related/affected genes. Notably, an interactive knowledge graph that systematically integrates all the HERV-disease associations and corresponding affected genes into a comprehensive network provides a powerful tool to uncover and deduce the complex interplay between HERVs and diseases. The HervD Atlas also features a user-friendly web interface that allows efficient browsing, searching, and downloading of all association information, research metadata, and annotation information. Overall, the HervD Atlas is an essential resource for comprehensive, up-to-date knowledge on HERV-disease research, potentially facilitating the development of novel HERV-associated diagnostic and therapeutic strategies.
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Affiliation(s)
- Cuidan Li
- CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences and China National Center for Bioinformation, Beijing 100101, China
| | - Qiheng Qian
- CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences and China National Center for Bioinformation, Beijing 100101, China
- National Genomics Data Center, Beijing Institute of Genomics, Chinese Academy of Sciences and China National Center for Bioinformation, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Chenghao Yan
- CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences and China National Center for Bioinformation, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Mingming Lu
- CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences and China National Center for Bioinformation, Beijing 100101, China
- National Genomics Data Center, Beijing Institute of Genomics, Chinese Academy of Sciences and China National Center for Bioinformation, Beijing 100101, China
| | - Lin Li
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing 100071, China
| | - Pan Li
- CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences and China National Center for Bioinformation, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Zhuojing Fan
- CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences and China National Center for Bioinformation, Beijing 100101, China
- National Genomics Data Center, Beijing Institute of Genomics, Chinese Academy of Sciences and China National Center for Bioinformation, Beijing 100101, China
| | - Wenyan Lei
- CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences and China National Center for Bioinformation, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Kang Shang
- CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences and China National Center for Bioinformation, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Peihan Wang
- CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences and China National Center for Bioinformation, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jie Wang
- CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences and China National Center for Bioinformation, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Tianyi Lu
- CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences and China National Center for Bioinformation, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yuting Huang
- State Key Laboratory of Elemento-Organic Chemistry, College of Chemistry, Nankai University, Tianjin 300071, China
| | - Hongwei Yang
- State Key Laboratory of Elemento-Organic Chemistry, College of Chemistry, Nankai University, Tianjin 300071, China
| | - Haobin Wei
- CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences and China National Center for Bioinformation, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jingwan Han
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing 100071, China
| | - Jingfa Xiao
- CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences and China National Center for Bioinformation, Beijing 100101, China
- National Genomics Data Center, Beijing Institute of Genomics, Chinese Academy of Sciences and China National Center for Bioinformation, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Fei Chen
- CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences and China National Center for Bioinformation, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
- Beijing Key Laboratory of Genome and Precision Medicine Technologies, Beijing100101, China
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3
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Nevalainen T, Autio A, Hurme M. Human endogenous retroviruses of the HERV-K (HML-2) family are expressed in the brain of healthy individuals and modify the composition of the brain-infiltrating immune cells. Heliyon 2023; 9:e21283. [PMID: 37920490 PMCID: PMC10618496 DOI: 10.1016/j.heliyon.2023.e21283] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Revised: 05/10/2023] [Accepted: 10/18/2023] [Indexed: 11/04/2023] Open
Abstract
Human endogenous retroviruses (HERVs) are remnants of ancient retroviral infections in the human genome. RNA expression of individual HERVs has frequently been observed in various pathologic conditions, but some activity can also be seen in healthy individuals, e.g. in the blood. To quantitate the basal expression levels of HERVs in the brain, we now used high-throughput sequencing-based metagenomic analysis to characterize the expression profiles of the HERV-K (HML-2) family proviruses in different brain regions of healthy brain tissue. To this end, RNA-seq data from the Genotype-Tissue Expression (GTEx) project was used. The GTEx project is a public resource to study tissue-specific gene expression and regulation, consisting of a large selection of sequenced samples from different tissues. The GTEx data used in this study consisted of 378 samples taken from 13 brain regions from 55 individuals. The data demonstrated that out of 99 intact proviruses in the family 58 were expressed, but the expression profiles were highly divergent and there were no significant differences in the expression profiles between the various anatomic regions of the brain. It is known that the brain contains a variety of infiltrating immune cells, which are probably of great importance both in the normal defense mechanisms as well as in the various pathogenic processes. Digital cytometry (CIBERSORTx) was used to quantify the proportions of the infiltrating immune cells in the same brain samples. Six most abundant (>5 % of the total population) cell types were observed to be CD4 memory resting T cells, M0 macrophages, plasma cells, CD8 T cells, CD4 memory activated T cells, and monocytes. Analysis of the correlations between the individual HERVs and infiltrating cell types indicated that a cluster of 6 HERVs had a notable correlation signature between T cell type infiltrating cell proportions and HERV RNA expression intensity. The correlations between inflammatory type infiltrating cells were negative or weak. Taken together, these data indicate that the expression of HERVs is associated with a T cell type immunity.
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Affiliation(s)
- Tapio Nevalainen
- Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
- Gerontology Research Center (GEREC), Tampere, Finland
- Tampere University Hospital, Finland
| | - Arttu Autio
- Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
- Gerontology Research Center (GEREC), Tampere, Finland
| | - Mikko Hurme
- Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
- Gerontology Research Center (GEREC), Tampere, Finland
- Tampere University Hospital, Finland
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Felley-Bosco E. Exploring the Expression of the «Dark Matter» of the Genome in Mesothelioma for Potentially Predictive Biomarkers for Prognosis and Immunotherapy. Cancers (Basel) 2023; 15:cancers15112969. [PMID: 37296931 DOI: 10.3390/cancers15112969] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2023] [Revised: 05/21/2023] [Accepted: 05/26/2023] [Indexed: 06/12/2023] Open
Abstract
Recent high-throughput RNA sequencing technologies have confirmed that a large part of the non-coding genome is transcribed. The priority for further investigations is nevertheless generally given in cancer to coding sequences, due to the obvious interest of finding therapeutic targets. In addition, several RNA-sequencing pipelines eliminate repetitive sequences, which are difficult to analyze. In this review, we shall focus on endogenous retroviruses. These sequences are remnants of ancestral germline infections by exogenous retroviruses. These sequences represent 8% of human genome, meaning four-fold the fraction of the genome encoding for proteins. These sequences are generally mostly repressed in normal adult tissues, but pathological conditions lead to their de-repression. Specific mesothelioma-associated endogenous retrovirus expression and their association to clinical outcome is discussed.
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Affiliation(s)
- Emanuela Felley-Bosco
- Laboratory of Molecular Oncology, Department of Thoracic Surgery, Zürich University Hospital, 8091 Zurich, Switzerland
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5
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Hamann MV, Adiba M, Lange UC. Confounding factors in profiling of locus-specific human endogenous retrovirus (HERV) transcript signatures in primary T cells using multi-study-derived datasets. BMC Med Genomics 2023; 16:68. [PMID: 37013607 PMCID: PMC10068191 DOI: 10.1186/s12920-023-01486-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Accepted: 03/11/2023] [Indexed: 04/05/2023] Open
Abstract
BACKGROUND Human endogenous retroviruses (HERV) are repetitive sequence elements and a substantial part of the human genome. Their role in development has been well documented and there is now mounting evidence that dysregulated HERV expression also contributes to various human diseases. While research on HERV elements has in the past been hampered by their high sequence similarity, advanced sequencing technology and analytical tools have empowered the field. For the first time, we are now able to undertake locus-specific HERV analysis, deciphering expression patterns, regulatory networks and biological functions of these elements. To do so, we inevitable rely on omics datasets available through the public domain. However, technical parameters inevitably differ, making inter-study analysis challenging. We here address the issue of confounding factors for profiling locus-specific HERV transcriptomes using datasets from multiple sources. METHODS We collected RNAseq datasets of CD4 and CD8 primary T cells and extracted HERV expression profiles for 3220 elements, resembling most intact, near full-length proviruses. Looking at sequencing parameters and batch effects, we compared HERV signatures across datasets and determined permissive features for HERV expression analysis from multiple-source data. RESULTS We could demonstrate that considering sequencing parameters, sequencing-depth is most influential on HERV signature outcome. Sequencing samples deeper broadens the spectrum of expressed HERV elements. Sequencing mode and read length are secondary parameters. Nevertheless, we find that HERV signatures from smaller RNAseq datasets do reliably reveal most abundantly expressed HERV elements. Overall, HERV signatures between samples and studies overlap substantially, indicating a robust HERV transcript signature in CD4 and CD8 T cells. Moreover, we find that measures of batch effect reduction are critical to uncover genic and HERV expression differences between cell types. After doing so, differences in the HERV transcriptome between ontologically closely related CD4 and CD8 T cells became apparent. CONCLUSION In our systematic approach to determine sequencing and analysis parameters for detection of locus-specific HERV expression, we provide evidence that analysis of RNAseq datasets from multiple studies can aid confidence of biological findings. When generating de novo HERV expression datasets we recommend increased sequence depth ( > = 100 mio reads) compared to standard genic transcriptome pipelines. Finally, batch effect reduction measures need to be implemented to allow for differential expression analysis.
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Affiliation(s)
| | - Maisha Adiba
- Leibniz Institute of Virology (LIV), Hamburg, Germany
| | - Ulrike C Lange
- Leibniz Institute of Virology (LIV), Hamburg, Germany.
- Institute for Infection Research and Vaccine Development, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
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Grandi N, Erbì MC, Scognamiglio S, Tramontano E. Human Endogenous Retrovirus (HERV) Transcriptome Is Dynamically Modulated during SARS-CoV-2 Infection and Allows Discrimination of COVID-19 Clinical Stages. Microbiol Spectr 2023; 11:e0251622. [PMID: 36602345 PMCID: PMC9927238 DOI: 10.1128/spectrum.02516-22] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
SARS-CoV-2 infection is known to trigger an important inflammatory response, which has a major role in COVID-19 pathogenesis. In infectious and inflammatory contexts, the modulation of human endogenous retroviruses (HERV) has been broadly reported, being able to further sustain innate immune responses due to the expression of immunogenic viral transcripts, including double-stranded DNA (dsRNA), and eventually, immunogenic proteins. To gain insights on this poorly characterized interplay, we performed a high-throughput expression analysis of ~3,300 specific HERV loci in the peripheral blood mononuclear cells (PBMCs) of 10 healthy controls and 16 individuals being either convalescent after the infection (6) or retesting positive after convalescence (10) (Gene Expression Onmibus [GEO] data set GSE166253). Results showed that the exposure to SARS-CoV-2 infection modulates HERV expression according to the disease stage and reflecting COVID-19 immune signatures. The differential expression analysis between healthy control (HC) and COVID-19 patients allowed us to identify a total of 282 differentially expressed HERV loci (deHERV) in the individuals exposed to SARS-CoV-2 infection, independently from the clinical form. In addition, 278 and 60 deHERV loci that were specifically modulated in individuals convalescent after COVID19 infection (C) and patients that retested positive to SARS-CoV-2 after convalescence (RTP) as individually compared to HC, respectively, as well as 164 deHERV loci between C and RTP patients were identified. The identified HERV loci belonged to 36 different HERV groups, including members of all three classes. The present study provides an exhaustive picture of the HERV transcriptome in PBMCs and its dynamic variation in the presence of COVID-19, revealing specific modulation patterns according to the infection stage that can be relevant to the disease clinical manifestation and outcome. IMPORTANCE We report here the first high-throughput analysis of HERV loci expression along SARS-CoV-2 infection, as performed with peripheral blood mononuclear cells (PBMCs). Such cells are not directly infected by the virus but have a crucial role in the plethora of inflammatory and immune events that constitute a major hallmark of COVID-19 pathogenesis. Results provide a novel and exhaustive picture of HERV expression in PBMCs, revealing specific modulation patterns according to the disease condition and the concomitant immune activation. To our knowledge, this is the first set of deHERVs whose expression is dynamically modulated across COVID-19 stages, confirming a tight interplay between HERV and cellular immunity and revealing specific transcriptional signatures that can have an impact on the disease clinical manifestation and outcome.
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Affiliation(s)
- Nicole Grandi
- Laboratory of Molecular Virology, Department of Life and Environmental Sciences, University of Cagliari, Cagliari, Italy
| | - Maria Chiara Erbì
- Laboratory of Molecular Virology, Department of Life and Environmental Sciences, University of Cagliari, Cagliari, Italy
| | - Sante Scognamiglio
- Laboratory of Molecular Virology, Department of Life and Environmental Sciences, University of Cagliari, Cagliari, Italy
| | - Enzo Tramontano
- Laboratory of Molecular Virology, Department of Life and Environmental Sciences, University of Cagliari, Cagliari, Italy
- Istituto di Ricerca Genetica e Biomedica, Consiglio Nazionale delle Ricerche, Cagliari, Italy
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7
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Scognamiglio S, Grandi N, Pessiu E, Tramontano E. Identification, comprehensive characterization, and comparative genomics of the HERV-K(HML8) integrations in the human genome. Virus Res 2023; 323:198976. [PMID: 36309315 PMCID: PMC10194239 DOI: 10.1016/j.virusres.2022.198976] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Revised: 10/19/2022] [Accepted: 10/20/2022] [Indexed: 11/06/2022]
Abstract
Around 8% of the human genome is composed by Human Endogenous Retroviruses (HERVs), ancient viral sequences inherited from the primate germ line after their infection by now extinct retroviruses. Given the still underexplored physiological and pathological roles of HERVs, it is fundamental to increase our information about the genomic composition of the different groups, to lay reliable foundation for functional studies. Among HERVs, the most characterized elements belong to the beta-like superfamily HERV-K, comprising 10 groups (HML1-10) with HML2 being the most recent and studied one. Among HMLs, the HML8 group is the only one still lacking a comprehensive genomic description. In the present work, we investigated HML8 sequences' distribution in the human genome (GRCh38/hg38), identifying 23 novel proviruses and characterizing the overall 78 HML8 proviruses in terms of genome structure, phylogeny, and integration pattern. HML8 elements were significantly enriched in human chromosomes 8 and X (p<0.005) while chromosomes 17 and 20 showed fewer integrations than expected (p<0.025 and p<0.005, respectively). Phylogenetic analyses classified HML8 members into 3 clusters, corresponding to the three LTR types MER11A, MER11B and MER11C. Besides different LTR types, common signatures in the internal structure suggested the potential existence of three different ancestral HML8 variants. Accordingly, time of integration estimation coupled with comparative genomics revealed that these three clusters have a different time of integration in the primates' genome, with MER11C elements being significantly younger than MER11A- and MER11B associated proviruses (p<0.005 and p<0.05, respectively). Approximately 30% of the HML8 elements were found co-localized within human genes, sometimes in exonic portions and with the same orientation, deserving further studies for their possible effects on gene expression. Overall, we provide the first detailed picture of the HML8 group distribution and variety among the genome, creating the backbone for the specific analysis of their transcriptional activity in healthy and diseased conditions.
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Affiliation(s)
- Sante Scognamiglio
- Department of Life and Environmental Sciences, Laboratory of Molecular Virology, University of Cagliari, Cittadella Universitaria di Monserrato, SS554, Monserrato, Cagliari 09042, Italy
| | - Nicole Grandi
- Department of Life and Environmental Sciences, Laboratory of Molecular Virology, University of Cagliari, Cittadella Universitaria di Monserrato, SS554, Monserrato, Cagliari 09042, Italy
| | - Eleonora Pessiu
- Department of Life and Environmental Sciences, Laboratory of Molecular Virology, University of Cagliari, Cittadella Universitaria di Monserrato, SS554, Monserrato, Cagliari 09042, Italy
| | - Enzo Tramontano
- Department of Life and Environmental Sciences, Laboratory of Molecular Virology, University of Cagliari, Cittadella Universitaria di Monserrato, SS554, Monserrato, Cagliari 09042, Italy; Istituto di Ricerca Genetica e Biomedica, Consiglio Nazionale delle Ricerche (CNR), Monserrato, Cagliari 09042, Italy.
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8
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She J, Du M, Xu Z, Jin Y, Li Y, Zhang D, Tao C, Chen J, Wang J, Yang E. The landscape of hervRNAs transcribed from human endogenous retroviruses across human body sites. Genome Biol 2022; 23:231. [PMID: 36329469 PMCID: PMC9632151 DOI: 10.1186/s13059-022-02804-w] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Accepted: 10/25/2022] [Indexed: 11/06/2022] Open
Abstract
BACKGROUND Human endogenous retroviruses (HERVs), the remnants of ancient retroviruses, account for 8% of the human genome, but most have lost their transcriptional abilities under physiological conditions. However, mounting evidence shows that several expressed HERVs do exert biological functions. Here, we systematically characterize physiologically expressed HERVs and examine whether they may give insight into the molecular fundamentals of human development and disease. RESULTS We systematically identify 13,889 expressed HERVs across normal body sites and demonstrate that they are expressed in body site-specific patterns and also by sex, ethnicity, and age. Analyzing cis-ERV-related quantitative trait loci, we find that 5435 hervRNAs are regulated by genetic variants. Combining this with a genome-wide association study, we elucidate that the dysregulation of expressed HERVs might be associated with various complex diseases, particularly neurodegenerative and psychiatric diseases. We further find that physiologically activated hervRNAs are associated with histone modifications rather than DNA demethylation. CONCLUSIONS Our results present a locus-specific landscape of physiologically expressed hervRNAs, which represent a hidden layer of genetic architecture in development and disease.
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Affiliation(s)
- Jianqi She
- Department of Microbiology & Infectious Disease Center, School of Basic Medical Sciences, Peking University Health Science Center, Key Laboratory for Neuroscience, Ministry of Education/National Health Commission of China, NHC Key Laboratory of Medical Immunology (Peking University), Beijing, 100191, China
- Department of Medical Bioinformatics, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, 100191, China
| | - Minghao Du
- Department of Microbiology & Infectious Disease Center, School of Basic Medical Sciences, Peking University Health Science Center, Key Laboratory for Neuroscience, Ministry of Education/National Health Commission of China, NHC Key Laboratory of Medical Immunology (Peking University), Beijing, 100191, China
- Department of Medical Bioinformatics, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, 100191, China
| | - Zhanzhan Xu
- Department of Medical Bioinformatics, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, 100191, China
- Department of Radiation Medicine, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, 100191, China
| | - Yueqi Jin
- Department of Microbiology & Infectious Disease Center, School of Basic Medical Sciences, Peking University Health Science Center, Key Laboratory for Neuroscience, Ministry of Education/National Health Commission of China, NHC Key Laboratory of Medical Immunology (Peking University), Beijing, 100191, China
- Department of Medical Bioinformatics, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, 100191, China
| | - Yu Li
- Chinese Institute for Brain Research, Beijing, 102206, China
| | - Daoning Zhang
- Peking University First Hospital, Beijing, 100034, China
| | - Changyu Tao
- Department of Human Anatomy, Histology & Embryology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, 100191, China
| | - Jian Chen
- Chinese Institute for Brain Research, Beijing, 102206, China
| | - Jiadong Wang
- Department of Radiation Medicine, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, 100191, China
| | - Ence Yang
- Department of Microbiology & Infectious Disease Center, School of Basic Medical Sciences, Peking University Health Science Center, Key Laboratory for Neuroscience, Ministry of Education/National Health Commission of China, NHC Key Laboratory of Medical Immunology (Peking University), Beijing, 100191, China.
- Department of Medical Bioinformatics, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, 100191, China.
- Chinese Institute for Brain Research, Beijing, 102206, China.
- Taizhou Medical New & Hi-tech Industrial Development Zone, Jiangsu, 225326, China.
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Richert-Pöggeler KR, Iskra-Caruana ML, Kishima Y. Editorial: DNA virus and host plant interactions from antagonism to endogenization. FRONTIERS IN PLANT SCIENCE 2022; 13:1014516. [PMID: 36161005 PMCID: PMC9493344 DOI: 10.3389/fpls.2022.1014516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Accepted: 08/24/2022] [Indexed: 06/16/2023]
Affiliation(s)
- Katja R. Richert-Pöggeler
- Julius Kuehn Institute, Federal Research Centre for Cultivated Plants, Institute for Epidemiology and Pathogen Diagnostics, Braunschweig, Germany
| | | | - Yuji Kishima
- Laboratory of Plant Breeding, Research Faculty of Agriculture, Hokkaido University, Sapporo, Japan
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10
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Mao J, Zhang Q, Cong YS. Human endogenous retroviruses in development and disease. Comput Struct Biotechnol J 2021; 19:5978-5986. [PMID: 34849202 PMCID: PMC8604659 DOI: 10.1016/j.csbj.2021.10.037] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2021] [Revised: 10/29/2021] [Accepted: 10/29/2021] [Indexed: 12/16/2022] Open
Abstract
Human endogenous retroviruses (HERVs) represent ∼8% of human genome, deriving from exogenous retroviral infections of germ line cells occurred millions of years ago and being inherited by the offspring in a Mendelian fashion. Most of HERVs are nonprotein-coding because of the accumulation of mutations, insertions, deletions, and/or truncations. It has been long thought that HERVs were "junk DNA". However, it is now known that HERVs are involved in various biological processes through encoding proteins, acting as promoters/enhancers, or lncRNAs to affect human health and disease. In this review, we summarized recent findings about HERVs, with implications in embryonic development, pluripotency, cancer, aging, and neurodegenerative diseases.
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Affiliation(s)
- Jian Mao
- Key Laboratory of Aging and Cancer Biology of Zhejiang Province, Hangzhou Normal University School of Basic Medical Sciences, Hangzhou, China
| | - Qian Zhang
- Key Laboratory of Aging and Cancer Biology of Zhejiang Province, Hangzhou Normal University School of Basic Medical Sciences, Hangzhou, China
| | - Yu-Sheng Cong
- Key Laboratory of Aging and Cancer Biology of Zhejiang Province, Hangzhou Normal University School of Basic Medical Sciences, Hangzhou, China
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11
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Grandi N, Pisano MP, Pessiu E, Scognamiglio S, Tramontano E. HERV-K(HML7) Integrations in the Human Genome: Comprehensive Characterization and Comparative Analysis in Non-Human Primates. BIOLOGY 2021; 10:biology10050439. [PMID: 34069102 PMCID: PMC8156875 DOI: 10.3390/biology10050439] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Revised: 05/10/2021] [Accepted: 05/11/2021] [Indexed: 12/18/2022]
Abstract
Simple Summary The human genome is not human at all, but it includes a multitude of sequences inherited from ancient viral infections that affected primates’ germ line. These elements can be seen as the fossils of now-extinct retroviruses, and are called Human Endogenous Retroviruses (HERVs). View as “junk DNA” for a long time, HERVs constitute 4 times the amount of DNA needed to produce all cellular proteins, and growing evidence indicates their crucial role in primate brain evolution, placenta development, and innate immunity shaping. HERVs are also intensively studied for a pathological role, even if the incomplete knowledge about their exact number and genomic position has thus far prevented any causal association. Among possible relevant HERVs, the HERV-K supergroup is of particular interest, including some of the oldest (HML5) as well as youngest (HML2) integrations. Among HERV-Ks, the HML7 group still lack a detailed description, and the present work thus aimed to identify and characterize all HML7 elements in the human genome. Results showed that the HML7 group includes 23 elements and an additional 160 “scars” of past infection that invaded in primates mostly between 20 and 30 million years ago, providing an exhaustive background to study their impact on human pathophysiology. Abstract Endogenous Retroviruses (ERVs) are ancient relics of infections that affected the primate germ line and constitute about 8% of our genome. Growing evidence indicates that ERVs had a major role in vertebrate evolution, being occasionally domesticated by the host physiology. In addition, human ERV (HERV) expression is highly investigated for a possible pathological role, even if no clear associations have been reported yet. In fact, on the one side, the study of HERV expression in high-throughput data is a powerful and promising tool to assess their actual dysregulation in diseased conditions; but, on the other side, the poor knowledge about the various HERV group genomic diversity and individual members somehow prevented the association between specific HERV loci and a given molecular mechanism of pathogenesis. The present study is focused on the HERV-K(HML7) group that—differently from the other HERV-K members—still remains poorly characterized. Starting from an initial identification performed with the software RetroTector, we collected 23 HML7 proviral insertions and about 160 HML7 solitary LTRs that were analyzed in terms of genomic distribution, revealing a significant enrichment in chromosome X and the frequent localization within human gene introns as well as in pericentromeric and centromeric regions. Phylogenetic analyses showed that HML7 members form a monophyletic group, which based on age estimation and comparative localization in non-human primates had its major diffusion between 20 and 30 million years ago. Structural characterization revealed that besides 3 complete HML7 proviruses, the other group members shared a highly defective structure that, however, still presents recognizable functional domains, making it worth further investigation in the human population to assess the presence of residual coding potential.
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Affiliation(s)
- Nicole Grandi
- Laboratory of Molecular Virology, Department of Life and Environmental Sciences, University of Cagliari, 09042 Monserrato, Cagliari, Italy; (M.P.P.); (E.P.); (S.S.); (E.T.)
- Correspondence:
| | - Maria Paola Pisano
- Laboratory of Molecular Virology, Department of Life and Environmental Sciences, University of Cagliari, 09042 Monserrato, Cagliari, Italy; (M.P.P.); (E.P.); (S.S.); (E.T.)
| | - Eleonora Pessiu
- Laboratory of Molecular Virology, Department of Life and Environmental Sciences, University of Cagliari, 09042 Monserrato, Cagliari, Italy; (M.P.P.); (E.P.); (S.S.); (E.T.)
| | - Sante Scognamiglio
- Laboratory of Molecular Virology, Department of Life and Environmental Sciences, University of Cagliari, 09042 Monserrato, Cagliari, Italy; (M.P.P.); (E.P.); (S.S.); (E.T.)
| | - Enzo Tramontano
- Laboratory of Molecular Virology, Department of Life and Environmental Sciences, University of Cagliari, 09042 Monserrato, Cagliari, Italy; (M.P.P.); (E.P.); (S.S.); (E.T.)
- Istituto di Ricerca Genetica e Biomedica, Consiglio Nazionale delle Ricerche (CNR), 09042 Monserrato, Cagliari, Italy
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Pisano MP, Grandi N, Tramontano E. Human Endogenous Retroviruses (HERVs) and Mammalian Apparent LTRs Retrotransposons (MaLRs) Are Dynamically Modulated in Different Stages of Immunity. BIOLOGY 2021; 10:biology10050405. [PMID: 34062989 PMCID: PMC8147956 DOI: 10.3390/biology10050405] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Revised: 04/26/2021] [Accepted: 04/30/2021] [Indexed: 12/25/2022]
Abstract
Human Endogenous retroviruses (HERVs) and Mammalian Apparent LTRs Retrotransposons (MaLRs) are remnants of ancient retroviral infections that represent a large fraction of our genome. The HERV and MaLR transcriptional activity is regulated in developmental stages, adult tissues, and pathological conditions. In this work, we used a bioinformatics approach based on RNA-sequencing (RNA-seq) to study the expression and modulation of HERVs and MaLR in a scenario of activation of the immune response. We analyzed transcriptome data from subjects before and after the administration of an inactivated vaccine against the Hantaan orthohantavirus, the causative agent of Korean hemorrhagic fever, to investigate the HERV and MaLR expression and differential expression in response to the administration of the vaccine. Specifically, we described the HERV transcriptome in PBMCs and identified HERV and MaLR loci differentially expressed after the 2nd, 3rd, and 4th inactivated vaccine administrations. We found that the expression of 545 HERV and MaLR elements increased in response to the vaccine and that the activation of several individual HERV and MaLR loci is specific for each vaccine administration and correlated to different genes and immune-related pathways.
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Ferrari R, Grandi N, Tramontano E, Dieci G. Retrotransposons as Drivers of Mammalian Brain Evolution. Life (Basel) 2021; 11:life11050376. [PMID: 33922141 PMCID: PMC8143547 DOI: 10.3390/life11050376] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 04/20/2021] [Accepted: 04/21/2021] [Indexed: 12/11/2022] Open
Abstract
Retrotransposons, a large and diverse class of transposable elements that are still active in humans, represent a remarkable force of genomic innovation underlying mammalian evolution. Among the features distinguishing mammals from all other vertebrates, the presence of a neocortex with a peculiar neuronal organization, composition and connectivity is perhaps the one that, by affecting the cognitive abilities of mammals, contributed mostly to their evolutionary success. Among mammals, hominids and especially humans display an extraordinarily expanded cortical volume, an enrichment of the repertoire of neural cell types and more elaborate patterns of neuronal connectivity. Retrotransposon-derived sequences have recently been implicated in multiple layers of gene regulation in the brain, from transcriptional and post-transcriptional control to both local and large-scale three-dimensional chromatin organization. Accordingly, an increasing variety of neurodevelopmental and neurodegenerative conditions are being recognized to be associated with retrotransposon dysregulation. We review here a large body of recent studies lending support to the idea that retrotransposon-dependent evolutionary novelties were crucial for the emergence of mammalian, primate and human peculiarities of brain morphology and function.
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Affiliation(s)
- Roberto Ferrari
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, 43124 Parma, Italy;
| | - Nicole Grandi
- Laboratory of Molecular Virology, Department of Life and Environmental Sciences, University of Cagliari, Cittadella Universitaria di Monserrato, 09042 Monserrato, Italy; (N.G.); (E.T.)
| | - Enzo Tramontano
- Laboratory of Molecular Virology, Department of Life and Environmental Sciences, University of Cagliari, Cittadella Universitaria di Monserrato, 09042 Monserrato, Italy; (N.G.); (E.T.)
- Istituto di Ricerca Genetica e Biomedica, Consiglio Nazionale delle Ricerche, 09042 Monserrato, Italy
| | - Giorgio Dieci
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, 43124 Parma, Italy;
- Correspondence:
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Gale Hammell M, Rowe HM. Editorial Overview: Endogenous Retroviruses in Development and Disease. Viruses 2020; 12:v12121446. [PMID: 33339171 PMCID: PMC7765662 DOI: 10.3390/v12121446] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Accepted: 12/14/2020] [Indexed: 11/16/2022] Open
Affiliation(s)
- Molly Gale Hammell
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA
- Correspondence: (M.G.H.); (H.M.R.)
| | - Helen M. Rowe
- Centre for Immunobiology, Blizard Institute, Queen Mary University of London, 4 Newark St, London E1 2AT, UK
- Correspondence: (M.G.H.); (H.M.R.)
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