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Wu X, Liu L, Xue X, Li X, Zhao K, Zhang J, Li W, Yao W, Ding S, Jia C, Zhu F. Captive ERVWE1 triggers impairment of 5-HT neuronal plasticity in the first-episode schizophrenia by post-transcriptional activation of HTR1B in ALKBH5-m6A dependent epigenetic mechanisms. Cell Biosci 2023; 13:213. [PMID: 37990254 PMCID: PMC10664518 DOI: 10.1186/s13578-023-01167-4] [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: 07/27/2023] [Accepted: 11/07/2023] [Indexed: 11/23/2023] Open
Abstract
BACKGROUND Abnormalities in the 5-HT system and synaptic plasticity are hallmark features of schizophrenia. Previous studies suggest that the human endogenous retrovirus W family envelope (ERVWE1) is an influential risk factor for schizophrenia and inversely correlates with 5-HT4 receptor in schizophrenia. To our knowledge, no data describes the effect of ERVWE1 on 5-HT neuronal plasticity. N6-methyladenosine (m6A) regulates gene expression and impacts synaptic plasticity. Our research aims to systematically investigate the effects of ERVWE1 on 5-HT neuronal plasticity through m6A modification in schizophrenia. RESULTS HTR1B, ALKBH5, and Arc exhibited higher levels in individuals with first-episode schizophrenia compared to the controls and showed a strong positive correlation with ERVWE1. Interestingly, HTR1B was also correlated with ALKBH5 and Arc. Further analyses confirmed that ALKBH5 may be an independent risk factor for schizophrenia. In vitro studies, we discovered that ERVWE1 enhanced HTR1B expression, thereby activating the ERK-ELK1-Arc pathway and reducing the complexity and spine density of 5-HT neurons. Furthermore, ERVWE1 reduced m6A levels through ALKBH5 demethylation. ERVWE1 induced HTR1B upregulation by improving its mRNA stability in ALKBH5-m6A-dependent epigenetic mechanisms. Importantly, ALKBH5 mediated the observed alterations in 5-HT neuronal plasticity induced by ERVWE1. CONCLUSIONS Overall, HTR1B, Arc, and ALKBH5 levels were increased in schizophrenia and positively associated with ERVWE1. Moreover, ALKBH5 was a novel risk gene for schizophrenia. ERVWE1 impaired 5-HT neuronal plasticity in ALKBH5-m6A dependent mechanism by the HTR1B-ERK-ELK1-Arc pathway, which may be an important contributor to aberrant synaptic plasticity in schizophrenia.
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Affiliation(s)
- Xiulin Wu
- State Key Laboratory of Virology, Department of Medical Microbiology, School of Basic Medical Sciences, Wuhan University, Wuhan, 430071, China
| | | | - Xing Xue
- State Key Laboratory of Virology, Department of Medical Microbiology, School of Basic Medical Sciences, Wuhan University, Wuhan, 430071, China
| | - Xuhang Li
- State Key Laboratory of Virology, Department of Medical Microbiology, School of Basic Medical Sciences, Wuhan University, Wuhan, 430071, China
| | - Kexin Zhao
- State Key Laboratory of Virology, Department of Medical Microbiology, School of Basic Medical Sciences, Wuhan University, Wuhan, 430071, China
| | - Jiahang Zhang
- State Key Laboratory of Virology, Department of Medical Microbiology, School of Basic Medical Sciences, Wuhan University, Wuhan, 430071, China
| | - Wenshi Li
- State Key Laboratory of Virology, Department of Medical Microbiology, School of Basic Medical Sciences, Wuhan University, Wuhan, 430071, China
| | - Wei Yao
- State Key Laboratory of Virology, Department of Medical Microbiology, School of Basic Medical Sciences, Wuhan University, Wuhan, 430071, China
| | - Shuang Ding
- State Key Laboratory of Virology, Department of Medical Microbiology, School of Basic Medical Sciences, Wuhan University, Wuhan, 430071, China
| | - Chen Jia
- State Key Laboratory of Virology, Department of Medical Microbiology, School of Basic Medical Sciences, Wuhan University, Wuhan, 430071, China
| | - Fan Zhu
- State Key Laboratory of Virology, Department of Medical Microbiology, School of Basic Medical Sciences, Wuhan University, Wuhan, 430071, China.
- Hubei Province Key Laboratory of Allergy & Immunology, Wuhan University, Wuhan, 430071, China.
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Hosseiniporgham S, Sechi LA. Anti-HERV-K Drugs and Vaccines, Possible Therapies against Tumors. Vaccines (Basel) 2023; 11:vaccines11040751. [PMID: 37112663 PMCID: PMC10144246 DOI: 10.3390/vaccines11040751] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Revised: 03/20/2023] [Accepted: 03/21/2023] [Indexed: 03/31/2023] Open
Abstract
The footprint of human endogenous retroviruses (HERV), specifically HERV-K, has been found in malignancies, such as melanoma, teratocarcinoma, osteosarcoma, breast cancer, lymphoma, and ovary and prostate cancers. HERV-K is characterized as the most biologically active HERV due to possession of open reading frames (ORF) for all Gag, Pol, and Env genes, which enables it to be more infective and obstructive towards specific cell lines and other exogenous viruses, respectively. Some factors might contribute to carcinogenicity and at least one of them has been recognized in various tumors, including overexpression/methylation of long interspersed nuclear element 1 (LINE-1), HERV-K Gag, and Env genes themselves plus their transcripts and protein products, and HERV-K reverse transcriptase (RT). Therapies effective for HERV-K-associated tumors mostly target invasive autoimmune responses or growth of tumors through suppression of HERV-K Gag or Env protein and RT. To design new therapeutic options, more studies are needed to better understand whether HERV-K and its products (Gag/Env transcripts and HERV-K proteins/RT) are the initiators of tumor formation or just the disorder’s developers. Accordingly, this review aims to present evidence that highlights the association between HERV-K and tumorigenicity and introduces some of the available or potential therapies against HERV-K-induced tumors.
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Human Endogenous Retrovirus as Therapeutic Targets in Neurologic Disease. Pharmaceuticals (Basel) 2021; 14:ph14060495. [PMID: 34073730 PMCID: PMC8225122 DOI: 10.3390/ph14060495] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Revised: 05/15/2021] [Accepted: 05/17/2021] [Indexed: 01/16/2023] Open
Abstract
Human endogenous retroviruses (HERVs) are ancient retroviral DNA sequences established into germline. They contain regulatory elements and encoded proteins few of which may provide benefits to hosts when co-opted as cellular genes. Their tight regulation is mainly achieved by epigenetic mechanisms, which can be altered by environmental factors, e.g., viral infections, leading to HERV activation. The aberrant expression of HERVs associates with neurological diseases, such as multiple sclerosis (MS) or amyotrophic lateral sclerosis (ALS), inflammatory processes and neurodegeneration. This review summarizes the recent advances on the epigenetic mechanisms controlling HERV expression and the pathogenic effects triggered by HERV de-repression. This article ends by describing new, promising therapies, targeting HERV elements, one of which, temelimab, has completed phase II trials with encouraging results in treating MS. The information gathered here may turn helpful in the design of new strategies to unveil epigenetic failures behind HERV-triggered diseases, opening new possibilities for druggable targets and/or for extending the use of temelimab to treat other associated diseases.
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Yuan Z, Yang Y, Zhang N, Soto C, Jiang X, An Z, Zheng WJ. Human Endogenous Retroviruses in Glioblastoma Multiforme. Microorganisms 2021; 9:764. [PMID: 33917421 PMCID: PMC8067472 DOI: 10.3390/microorganisms9040764] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Revised: 03/28/2021] [Accepted: 03/29/2021] [Indexed: 12/13/2022] Open
Abstract
Glioblastoma multiforme (GBM) is the most aggressive and deadly brain tumor. It is primarily diagnosed in the elderly and has a 5-year survival rate of less than 6% even with the most aggressive therapies. The lack of biomarkers has made the development of immunotherapy for GBM challenging. Human endogenous retroviruses (HERVs) are a group of viruses with long terminal repeat (LTR) elements, which are believed to be relics from ancient viral infections. Recent studies have found that those repetitive elements play important roles in regulating various biological processes. The differentially expressed LTR elements from HERVs are potential biomarkers for immunotherapy to treat GBM. However, the understanding of the LTR element expression in GBM is greatly lacking. METHODS We obtained 1077.4 GB of sequencing data from public databases. These data were generated from 111 GBM tissue studies, 30 GBM cell lines studies, and 45 normal brain tissues studies. We analyzed repetitive elements that were differentially expressed in GBM and normal brain samples. RESULTS We found that 48 LTR elements were differentially expressed (p-value < 0.05) between GBM and normal brain tissues, of which 46 were HERV elements. Among these 46 elements, 34 significantly changed HERVs belong to the ERV1 superfamily. Furthermore, 43 out of the 46 differentially expressed HERV elements were upregulated. CONCLUSION Our results indicate significant differential expression of many HERV LTR elements in GBM and normal brain tissues. Expression levels of these elements could be developed as biomarkers for GBM treatments.
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Affiliation(s)
- Zihao Yuan
- School of Biomedical Informatics, University of Texas Health Science Center at Houston, Houston, TX 77030, USA; (Z.Y.); (Y.Y.); (X.J.)
- Texas Therapeutics Institute, Institute of Molecular Medicine, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX 77030, USA;
| | - Yuntao Yang
- School of Biomedical Informatics, University of Texas Health Science Center at Houston, Houston, TX 77030, USA; (Z.Y.); (Y.Y.); (X.J.)
| | - Ningyan Zhang
- Texas Therapeutics Institute, Institute of Molecular Medicine, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX 77030, USA;
| | - Claudio Soto
- Department of Neurology, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX 77030, USA;
| | - Xiaoqian Jiang
- School of Biomedical Informatics, University of Texas Health Science Center at Houston, Houston, TX 77030, USA; (Z.Y.); (Y.Y.); (X.J.)
| | - Zhiqiang An
- Texas Therapeutics Institute, Institute of Molecular Medicine, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX 77030, USA;
| | - Wenjin Jim Zheng
- School of Biomedical Informatics, University of Texas Health Science Center at Houston, Houston, TX 77030, USA; (Z.Y.); (Y.Y.); (X.J.)
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Luganini A, Gribaudo G. Retroviruses of the Human Virobiota: The Recycling of Viral Genes and the Resulting Advantages for Human Hosts During Evolution. Front Microbiol 2020; 11:1140. [PMID: 32547531 PMCID: PMC7270195 DOI: 10.3389/fmicb.2020.01140] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Accepted: 05/05/2020] [Indexed: 12/25/2022] Open
Abstract
All humans are colonized by a vast diversity of microbes (bacteria, archaea, protozoa, yeast, and fungi; collectively referred to as the microbiota) and viruses (the virobiota). This latter group includes viruses infecting prokaryotic cells (bacteriophages), viruses infecting eukaryotic-host cells, and virus-derived genetic elements present in host chromosomes. Although these eukaryotic viruses are mostly known to be pathogens, they are also able to establish mutualistic relationships with humans. Little is known about the mutualistic aspects of viral infection. Nevertheless, it is clear that evolution of some animal virus-host interactions has led to benefits in the health of the hosts, as is the case with symbiogenesis and endogenization of retroviruses that has exerted a neuroprotective effect on the human brain, and an important role in the fetal development, thus on the evolution of host species. In this review, we summarize how retroviruses provide amazing examples of cooperative-evolution, i.e., successful exchange between viruses and host, and how, in some cases, the benefits have become essential for the hosts’ survival.
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Affiliation(s)
- Anna Luganini
- Laboratory of Microbiology and Virology, Department of Life Sciences and Systems Biology, University of Turin, Turin, Italy
| | - Giorgio Gribaudo
- Laboratory of Microbiology and Virology, Department of Life Sciences and Systems Biology, University of Turin, Turin, Italy
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Parrish NF, Tomonaga K. Endogenized viral sequences in mammals. Curr Opin Microbiol 2016; 31:176-183. [PMID: 27128186 DOI: 10.1016/j.mib.2016.03.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Revised: 03/15/2016] [Accepted: 03/15/2016] [Indexed: 12/13/2022]
Abstract
Reverse-transcribed RNA molecules compose a significant portion of the human genome. Many of these RNA molecules were retrovirus genomes either infecting germline cells or having done so in a previous generation but retaining transcriptional activity. This mechanism itself accounts for a quarter of the genomic sequence information of mammals for which there is data. We understand relatively little about the causes and consequences of retroviral endogenization. This review highlights functions ascribed to sequences of viral origin endogenized into mammalian genomes and suggests some of the most pressing questions raised by these observations.
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Affiliation(s)
- Nicholas F Parrish
- Section of Surgical Sciences, Vanderbilt University Medical Center, Nashville, TN 37232, United States.
| | - Keizo Tomonaga
- Department of Viral Oncology, Institute for Virus Research, Kyoto University, Kyoto 606-8507, Japan; Department of Tumor Viruses, Graduate School of Medicine, Kyoto University, Kyoto 606-8507, Japan; Department of Mammalian Regulatory Network, Graduate School of Biostudies, Kyoto University, Kyoto 606-8507, Japan.
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Hummel J, Kämmerer U, Müller N, Avota E, Schneider-Schaulies S. Human endogenous retrovirus envelope proteins target dendritic cells to suppress T-cell activation. Eur J Immunol 2015; 45:1748-59. [PMID: 25752285 DOI: 10.1002/eji.201445366] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2014] [Revised: 02/04/2015] [Accepted: 03/03/2015] [Indexed: 01/27/2023]
Abstract
Though mostly defective, human endogenous retroviruses (HERV) can retain open reading frames, which are especially expressed in the placenta. There, the envelope (env) proteins of HERV-W (Syncytin-1), HERV-FRD (Syncytin-2), and HERV-K (HML-2) were implicated in tolerance against the semi-allogenic fetus. Here, we show that the known HERV env-binding receptors ASCT-1 and -2 and MFSD2 are expressed by DCs and T-cells. When used as effectors in coculture systems, CHO cells transfected to express Syncytin-1, -2, or HML-2 did not affect T-cell expansion or overall LPS-driven phenotypic DC maturation, however, promoted release of IL-12 and TNF-α rather than IL-10. In contrast, HERV env expressing choriocarcinoma cell lines suppressed T-cell proliferation and LPS-induced TNF-α and IL-12 release, however, promoted IL-10 accumulation, indicating that these effects might not rely on HERV env interactions. However, DCs conditioned by choriocarcinoma, but also transgenic CHO cells failed to promote allogenic T-cell expansion. This was associated with a loss of DC/T-cell conjugate frequencies, impaired Ca(2+) mobilization, and aberrant patterning of f-actin and tyrosine phosphorylated proteins in T-cells. Altogether, these findings suggest that HERV env proteins target T-cell activation indirectly by modulating the stimulatory activity of DCs.
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Affiliation(s)
- Jonas Hummel
- Institute for Virology and Immunobiology, University of Wuerzburg, Wuerzburg, Germany
| | - Ulrike Kämmerer
- Department of Obstetrics and Gynaecology, University of Wuerzburg, Wuerzburg, Germany
| | - Nora Müller
- Institute for Virology and Immunobiology, University of Wuerzburg, Wuerzburg, Germany
| | - Elita Avota
- Institute for Virology and Immunobiology, University of Wuerzburg, Wuerzburg, Germany
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Lokossou AG, Toudic C, Barbeau B. Implication of human endogenous retrovirus envelope proteins in placental functions. Viruses 2014; 6:4609-27. [PMID: 25421890 PMCID: PMC4246240 DOI: 10.3390/v6114609] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2014] [Revised: 11/02/2014] [Accepted: 11/07/2014] [Indexed: 12/21/2022] Open
Abstract
Human endogenous retroviruses (ERVs) represent 8% of the total human genome. Although the majority of these ancient proviral sequences have only retained non-coding long terminal repeats (LTRs), a number of “endogenized” retroviral genes encode functional proteins. Previous studies have underlined the implication of these ERV-derived proteins in the development and the function of the placenta. In this review, we summarize recent findings showing that two ERV genes, termed Syncytin-1 and Syncytin-2, which encode former envelope (Env) proteins, trigger fusion events between villous cytotrophoblasts and the peripheral multinucleated syncytiotrophoblast layer. Such fusion events maintain the stability of this latter cell structure, which plays an important role in fetal development by the active secretion of various soluble factors, gas exchange and regulation of fetomaternal immunotolerance. We also highlight new studies showing that these ERV proteins, in addition to their localization at the cell surface of cytotrophoblasts, are also incorporated on the surface of various extracellular microvesicles, including exosomes. Such exosome-associated proteins could be involved in the various functions attributed to these vesicles and could provide a form of tropism. Additionally, through their immunosuppressive domains, these ERV proteins could also contribute to fetomaternal immunotolerance in a local and more distal manner. These various aspects of the implication of Syncytin-1 and -2 in placental function are also addressed in the context of the placenta-related disorder, preeclampsia.
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Affiliation(s)
- Adjimon Gatien Lokossou
- Département des Sciences Biologiques and Centre de recherche BioMed, Université du Québec à Montréal, 2080 Saint-Urbain, Montréal, PQ H2X 3X8, Canada.
| | - Caroline Toudic
- Département des Sciences Biologiques and Centre de recherche BioMed, Université du Québec à Montréal, 2080 Saint-Urbain, Montréal, PQ H2X 3X8, Canada.
| | - Benoit Barbeau
- Département des Sciences Biologiques and Centre de recherche BioMed, Université du Québec à Montréal, 2080 Saint-Urbain, Montréal, PQ H2X 3X8, Canada.
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Pathological and evolutionary implications of retroviruses as mobile genetic elements. Genes (Basel) 2013; 4:573-82. [PMID: 24705263 PMCID: PMC3927575 DOI: 10.3390/genes4040573] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2013] [Revised: 09/27/2013] [Accepted: 10/08/2013] [Indexed: 11/17/2022] Open
Abstract
Retroviruses, a form of mobile genetic elements, have important roles in disease and primate evolution. Exogenous retroviruses, such as human immunodeficiency virus (HIV), have significant pathological implications that have created a massive public health challenge in recent years. Endogenous retroviruses (ERVs), which are the primary focus of this review, can also be pathogenic, as well as being beneficial to a host in some cases. Furthermore, retroviruses may have played a key role in primate evolution that resulted in the incorporation of these elements into the human genome. Retroviruses are mobile genetic elements that have important roles in disease and primate evolution. We will further discuss the pathogenic potential of retroviruses, including their role in cancer biology, and will briefly summarize their evolutionary implications.
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Cegolon L, Salata C, Weiderpass E, Vineis P, Palù G, Mastrangelo G. Human endogenous retroviruses and cancer prevention: evidence and prospects. BMC Cancer 2013; 13:4. [PMID: 23282240 PMCID: PMC3557136 DOI: 10.1186/1471-2407-13-4] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2012] [Accepted: 12/02/2012] [Indexed: 12/05/2022] Open
Abstract
Background Cancer is a significant and growing problem worldwide. While this increase may, in part, be attributed to increasing longevity, improved case notifications and risk-enhancing lifestyle (such as smoking, diet and obesity), hygiene-related factors resulting in immuno-regulatory failure may also play a major role and call for a revision of vaccination strategies to protect against a range of cancers in addition to infections. Discussion Human endogenous retroviruses (HERVs) are a significant component of a wider family of retroelements that constitutes part of the human genome. They were originated by the integration of exogenous retroviruses into the human genome millions of years ago. HERVs are estimated to comprise about 8% of human DNA and are ubiquitous in somatic and germinal tissues. Physiologic and pathologic processes are influenced by some biologically active HERV families. HERV antigens are only expressed at low levels by the host, but in circumstances of inappropriate control their genes may initiate or maintain pathological processes. Although the precise mechanism leading to abnormal HERVs gene expression has yet to be clearly elucidated, environmental factors seem to be involved by influencing the human immune system. HERV-K expression has been detected in different types of tumors. Among the various human endogenous retroviral families, the K series was the latest acquired by the human species. Probably because of its relatively recent origin, the HERV-K is the most complete and biologically active family. The abnormal expression of HERV-K seemingly triggers pathological processes leading to melanoma onset, but also contributes to the morphological and functional cellular modifications implicated in melanoma maintenance and progression. The HERV-K-MEL antigen is encoded by a pseudo-gene incorporated in the HERV-K env-gene. HERV-K-MEL is significantly expressed in the majority of dysplastic and normal naevi, as well as other tumors like sarcoma, lymphoma, bladder and breast cancer. An amino acid sequence similar to HERV-K-MEL, recognized to cause a significant protective effect against melanoma, is shared by the antigenic determinants expressed by some vaccines such as BCG, vaccinia virus and the yellow fever virus. HERV-K are also reactivated in the majority of human breast cancers. Monoclonal and single-chain antibodies against the HERV-K Env protein recently proved capable of blocking the proliferation of human breast cancer cells in vitro, inhibiting tumor growth in mice bearing xenograft tumors. Summary A recent epidemiological study provided provisional evidence of how melanoma risk could possibly be reduced if the yellow fever virus vaccine (YFV) were received at least 10 years before, possibly preventing tumor initiation rather than culling melanoma cells already compromised. Further research is recommended to confirm the temporal pattern of this protection and eliminate/attenuate the potential role of relevant confounders as socio-economic status and other vaccinations. It appears also appropriate to examine the potential protective effect of YFV against other malignancies expressing high levels of HERV-K antigens, namely breast cancer, sarcoma, lymphoma and bladder cancer. Tumor immune-therapy, as described for the monoclonal antibodies against breast cancer, is indeed considered more complex and less advantageous than immune-prevention. Cellular immunity possibly triggered by vaccines as for YFV might also be involved in anti-cancer response, in addition to humoral immunity.
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Affiliation(s)
- Luca Cegolon
- Department of Molecular Medicine, Padua University, Padua, Italy.
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Vargas A, Toufaily C, LeBellego F, Rassart É, Lafond J, Barbeau B. Reduced expression of both syncytin 1 and syncytin 2 correlates with severity of preeclampsia. Reprod Sci 2011; 18:1085-91. [PMID: 21493955 DOI: 10.1177/1933719111404608] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Human endogenous retroviruses (HERVs) represent up to 8% of the human genome and express several of its genes in the placenta. Studies have demonstrated that HERV envelope proteins syncytins 1 and 2 play a crucial role in trophoblast fusion and placenta development. Here, we compared the levels of placental expression of syncytins with the severity of preeclampsia (PE) symptoms. Confocal microscopy experiments indicated a pronounced deficiency in cellular fusion in trophoblast cells from patients with PE when compared to controls. As determined by quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) and Western blot analyses, syncytin mRNA and protein levels were decreased in PE placentas versus controls. Interestingly, syncytin 2 levels were more importantly impaired than syncytin 1. Our results further highlighted the existence of a correlation between the extent of the decrease in the expression levels of both fusogenic proteins and the degree of severity of PE symptoms. These HERV proteins could thereby be used as potential markers for the early diagnosis of PE.
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Affiliation(s)
- Amandine Vargas
- Université du Québec à Montréal, Département des sciences biologiques and Centre de recherche BioMed, Montréal, Québec, Canada
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Regulatory T-cell expansion during chronic viral infection is dependent on endogenous retroviral superantigens. Proc Natl Acad Sci U S A 2011; 108:3677-82. [PMID: 21321220 DOI: 10.1073/pnas.1100213108] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Regulatory T cells (Treg) play critical roles in the modulation of immune responses to infectious agents. Further understanding of the factors that control Treg activation and expansion in response to pathogens is needed to manipulate Treg function in acute and chronic infections. Here we show that chronic, but not acute, infection of mice with lymphocytic choriomeningitis virus results in a marked expansion of Foxp3(+) Treg that is dependent on retroviral superantigen (sag) genes encoded in the mouse genome. Sag-dependent Treg expansion was MHC class II dependent, CD4 independent, and required dendritic cells. Thus, one unique mechanism by which certain infectious agents evade host immune responses may be mediated by endogenous Sag-dependent activation and expansion of Treg.
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Krone B, Grange JM. Melanoma, Darwinian medicine and the inner world. J Cancer Res Clin Oncol 2010; 136:1787-94. [PMID: 20852885 PMCID: PMC2962785 DOI: 10.1007/s00432-010-0949-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2010] [Accepted: 09/02/2010] [Indexed: 12/12/2022]
Abstract
INTRODUCTION A diverse range of human diseases, including allergy, asthma, autoimmune disease, cancer and chronic neurologic diseases, notably multiple sclerosis and endogenous depression, is becoming more prevalent in industrialized countries. It has been postulated that environmental factors associated with improved standards of hygiene play a leading role in this process since the immune system seems to need extrinsic challenges for its proper maturation. THE INNER WORLD An added dimension has now emerged--the impact on disease of the inner world, principally the numerous endogenous retroviruses (HERVs) within the human genome. Taking melanoma as an example, we propose a framework for understanding how a complex infectious and immunological background can induce or inhibit expression of a HERV-related disease process. The central role of a failure to induce or to maintain certain populations of self-specific CD8(+) T-cells mediating immune surveillance, the expression of HERV-encoded peptides on affected cells and pathological mechanisms directly attributable to HERV proteins are discussed. CONCLUSIONS The presented concepts explain events preceding the clinical manifestation of diseases by several years and provide a rationale for the use of currently available vaccines to protect against certain HERV-induced diseases, especially melanoma. Criteria for establishing the causal role of HERVs in a given disease are proposed.
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Affiliation(s)
- B. Krone
- Centre for Hygiene and Human Genetics, University Göttingen, Göttingen, Germany
| | - J. M. Grange
- Centre for Infectious Diseases and International Health, University College London, 46 Cleveland Street, London, W1T 3JF UK
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Kwon DN, Lee YK, Greenhalgh DG, Cho K. Lipopolysaccharide stress induces cell-type specific production of murine leukemia virus type-endogenous retroviral virions in primary lymphoid cells. J Gen Virol 2010; 92:292-300. [PMID: 20965985 PMCID: PMC3081078 DOI: 10.1099/vir.0.023416-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Some murine-endogenous retroviruses, making up ∼10 % of the mouse genome, are induced during the course of experimental sepsis in which lipopolysaccharide (LPS), a pathogenic component of gram-negative bacteria, often plays a critical role. In this study, we investigated whether LPS stress induces the production of murine leukemia virus type-endogenous retrovirus (MuLV-ERV) virions in primary lymphoid cells. LPS treatment of cells (single-cell suspensions and sorted B- and T-cells) isolated from seven lymphoid organs of C57BL/6J mice resulted in a differential increase in the production of MuLV-ERV virions in most cells examined. Interestingly, among the 34 unique MuLV-ERV U3 sequences cloned from the viral genomic RNAs, the nuclear respiratory factor 1 (transcription factor) element was present only in the 20 U3 sequences that were derived from the LPS-induced MuLV-ERV U3 bands. Using the U3 sequences as a probe, 55 putative MuLV-ERV loci were mapped onto the C57BL/6J mouse genome and 15 of them retained full coding potential. Furthermore, one full-length recombinant MuLV-ERV originating from a locus on chromosome 13 was determined to be responsive to LPS stress. The findings from this study suggest that LPS stress differentially activates MuLV-ERV virion production in lymphoid organs in a cell type- and MuLV-ERV-specific manner. Further investigation is needed to define the role of MuLV-ERVs in the LPS signalling pathway(s) in general, as well as in the pathogenesis of sepsis.
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Affiliation(s)
- Deug-Nam Kwon
- Burn Research, Shriners Hospitals for Children Northern California and Department of Surgery, University of California, Davis, Sacramento, CA 95817, USA
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Panaro MA, Calvello R, Mitolo CI, Sisto M, Saccia M, Cianciulli A. An analysis of the human and mouse CXCR5 gene introns. Immunopharmacol Immunotoxicol 2010; 33:342-6. [PMID: 20809769 DOI: 10.3109/08923973.2010.512012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Both mouse and human chemokine receptor CXC motif 5 (CXCR5) genes exhibit one single intron interrupting the coding sequence. The mouse intron is 12053 nucleotides (nt) long; the human intron is 9603 nt long. Sections of the mouse intron significantly align plus/plus with sections of the human intron; the aligned segments are in the same order in mouse as in man and overall cover 13% of the mouse sequence and 17% of the human sequence. The human CXCR5 intron harbors sequences derived from retroviruses (human endogenous retroviruses). The mouse intron comprises very similar sequences. About 70% of the mouse intron sequence is 'specific' to this gene, while sequences in the rest of the intron are shared with many other genes located on different chromosomes. In the human the coverage by specific sequences is about 87%. Thus, the contribution of transposable elements is significantly higher in mouse (30%) than in man (13%). Intra-intronic plus/minus alignments exist in mouse (10 couples) and man (two couples): these may form stem and loop structures determining the secondary structure of the corresponding pre-mRNAs.
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Panaro MA, Calvello R, Mitolo CI, Sisto M, Cianciulli A. Evidence for endogenous retroviruses in human chemokine receptor gene introns: possible evolutionary inferences and biological roles. Immunopharmacol Immunotoxicol 2010; 33:291-301. [PMID: 21054205 DOI: 10.3109/08923973.2010.503243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The human chemokine receptor (CKR) genes CCR2, CCR6, CCR7, CCR9, CCR10, CXCR4, and CXCR5 harbor one or two introns. CCR7, CCR9, CCR10, and CXCR5 introns, (but not CCR2, CCR6, and CXCR4 introns) encompass retrovirus-like inserts with the characteristics of SINEs (short interspersed nuclear elements) up to 300 nucleotides (nt) long. Other characteristic elements of the retroviral genome, such as long terminal repeats and gag, pol, and env genes, are lacking. The inserts likely derived from one (or more) of the following retroviruses: XA34 (NCBI GenBank Nucleotides, U29659), HERV-P-T47D (AF087913), ERV FTD (U27241), HERV-K (Y17832), HML6p (U86698), HERV-H/env60 (AJ289710), XA38 (U37066). Virus-like inserts are remarkably homogeneous in all CKR introns, with nt identities of about 80%. Percentages of nt identities between the CKR inserts and the corresponding viral sequences are also about 80%. With reference to the CKR sequence, the viral sequence aligns in some instances Plus/Plus (XA34, HML6p, HERV-H/env60, and XA38) and in other instances Plus/Minus (HERV-P-T47D, ERV FTD, and HERV-K). Some aspects of the evolution of retroviruses and CKRs as well as hypotheses on the biological significance of the SINE inserts are discussed.
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Panaro MA, Calvello R, Lisi S, Saccia M, Mitolo CI, Cianciulli A. Viral sequence integration into introns of chemokine receptor genes. Immunopharmacol Immunotoxicol 2009; 31:589-94. [DOI: 10.3109/08923970902862284] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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19
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Syncytin-2 Plays an Important Role in the Fusion of Human Trophoblast Cells. J Mol Biol 2009; 392:301-18. [DOI: 10.1016/j.jmb.2009.07.025] [Citation(s) in RCA: 126] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2009] [Revised: 06/29/2009] [Accepted: 07/07/2009] [Indexed: 11/22/2022]
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CLONING AND CHARACTERIZATION OF ENDOGENOUS RETROVIRUSES ASSOCIATED WITH POSTINJURY STRESS SIGNALS IN LYMPHOID TISSUES. Shock 2009; 32:80-8. [DOI: 10.1097/shk.0b013e31818bc193] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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21
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Guilhou JJ, Molès JP. New Hypotheses in the Genetics of Psoriasis and Other ‘Complex’ Diseases. Dermatology 2008; 216:87-92. [DOI: 10.1159/000111504] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2007] [Accepted: 07/18/2007] [Indexed: 12/30/2022] Open
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Abstract
Phytoestrogens are estrogen-like substances produced by plants that account for some of the constituents present in vegetation that may be responsible for the health benefits of a diet rich in fruit and vegetables. Phytoestrogens have a plethora of different actions that they are capable of exerting on cellular metabolism. This review will focus on some of the major non-estrogen receptor-mediated cellular effects used by phytoestrogens and will draw attention to the fact that while they may have a number of beneficial effects, particularly in offering a protective effect against some hormone-dependent cancers, such as breast and prostate cancer, they may also have possible unfavorable effects by interfering with the functioning of normal cellular activities such as receptor-mediated signal transduction and DNA replication, as well as being genotoxic, mutagenic and promoting the proliferation of some cancer cells.
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Affiliation(s)
- Jan H J Martin
- University of Wolverhampton, Research Institute of Healthcare Science, Wulfruna Street, Wolverhampton, UK.
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Martin JHJ, Crotty S, Warren P, Nelson PN. Does an apple a day keep the doctor away because a phytoestrogen a day keeps the virus at bay? A review of the anti-viral properties of phytoestrogens. PHYTOCHEMISTRY 2007; 68:266-74. [PMID: 17182070 DOI: 10.1016/j.phytochem.2006.11.018] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2006] [Revised: 10/17/2006] [Accepted: 11/03/2006] [Indexed: 05/13/2023]
Abstract
From dengue to herpes and influenza to AIDS, the phytoestrogens that are present in many fruits and vegetables have been shown to exert anti-viral properties. Here we review the various different anti-viral mechanisms employed by phytoestrogens.
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Affiliation(s)
- J H J Martin
- Research Institute of Healthcare Science, University of Wolverhampton, Wulfruna Street, Wolverhampton, WV1 1SB, United Kingdom.
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Weis S, Llenos IC, Sabunciyan S, Dulay JR, Isler L, Yolken R, Perron H. Reduced expression of human endogenous retrovirus (HERV)-W GAG protein in the cingulate gyrus and hippocampus in schizophrenia, bipolar disorder, and depression. J Neural Transm (Vienna) 2007; 114:645-55. [PMID: 17219017 DOI: 10.1007/s00702-006-0599-y] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2006] [Accepted: 10/28/2006] [Indexed: 12/01/2022]
Abstract
The human endogenous retrovirus (HERV)-W multicopy family was identified in human DNA from the previously characterized multiple sclerosis associated retroviral element (MSRV). Upregulation of the HERV-W POL has been reported in cerebrospinal fluid of patients with schizophrenia. The expression of capsid (GAG) protein of HERV-W was studied by immunohistochemistry and western blotting in postmortem brain tissue of the anterior cingulate cortex and hippocampal formation of normal controls and of patients with schizophrenia, bipolar disorder and major depression. A physiological expression of GAG protein was detected in neurons as well as astroglial cells in normal brain both in the anterior cingulate cortex and in the hippocampal formation. There was a statistically significant reduction of this expression in neurons and astroglial cells in brains from individuals with schizophrenia, major depression, and bipolar disorder. The results from the present study confirm that GAG protein encoded by the HERV-W multicopy gene family is expressed in cells of the central nervous system under normal conditions. Our findings of a cell type-, brain region- and disease-specific reduced expression in schizophrenia, major depression, and bipolar disorder are compatible with a pathophysiological role of HERVs in human brain disorders. The causes and biological consequences of this differential regulation will be the subject of further investigations.
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Affiliation(s)
- S Weis
- Laboratory of Brain Research and Neuropathology, Departments of Psychiatry and Pathology, Uniformed Services University of the Health Sciences, and Stanley Medical Research Institute, Bethesda, MD, USA.
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25
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Illarionova AE, Vinogradova TV, Sverdlov ED. Only those genes of the KIAA1245 gene subfamily that contain HERV(K) LTRs in their introns are transcriptionally active. Virology 2006; 358:39-47. [PMID: 16997346 DOI: 10.1016/j.virol.2006.06.027] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2006] [Revised: 04/13/2006] [Accepted: 06/21/2006] [Indexed: 11/26/2022]
Abstract
Insertion of LTRs into some genome locations might seriously affect regulation of the neighboring genes expression. This hypothesis is widely accepted but, however, not confirmed directly. Earlier, we have identified a family of closely related genes highly similar to the KIAA1245 mRNA counterpart. This family included a subfamily of genes some of which contained and the others lacked an LTR in their structure. We compared transcription of several closely related genes of the subfamily differing in the presence or absence of LTRs. Only LTR-containing genes were transcribed in transformed cell lines, tumorous and embryonic human tissues, whereas LTR-lacking genes remained silent. Since the genes were in the same intracellular microenvironment, we suggested that this effect was most probably due to intrinsic cis-characteristics of integrated LTRs and confirmed this by demonstrating high enhancer activity of KIAA1245 LTRs. The expression of the LTR-containing genes in embryonic tissues might suggest their involvement in evolutionary events during primate speciation.
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Affiliation(s)
- A E Illarionova
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 16/10 Miklukho-Maklaya, Moscow 117997, Russia
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26
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Abstract
Consideration of virus evolution only from a disease perspective has provided a limited view of virus–host evolution. Such views assume all viruses fit predator/prey models for replication, but fail to explain the origin of disease or how viruses might make significant contributions to host evolution. On a long evolutionary time scale, the ability of a virus to persist in an individual host is a much more prevalent life strategy. Persistence can explain both origins of most viral disease and virus–host evolutionary stability. However, persistence (both genomic and epigenomic) is a much more complex and demanding virus–host relationship that is difficult to study. We must change our attitudes towards persistence if we are to understand how viruses shape the tree of life.
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Affiliation(s)
- Luis P Villarreal
- University of California, Center for Virus Research, 3232 McGaugh Hall, Irvine, CA 92697, USA
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Schulz WA, Steinhoff C, Florl AR. Methylation of endogenous human retroelements in health and disease. Curr Top Microbiol Immunol 2006; 310:211-50. [PMID: 16909913 DOI: 10.1007/3-540-31181-5_11] [Citation(s) in RCA: 121] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Retroelements constitute approximately 45% of the human genome. Long interspersed nuclear element (LINE) autonomous retrotransposons are predominantly represented by LINE-1, nonautonomous small interspersed nuclear elements (SINEs) are primarily represented by ALUs, and LTR retrotransposons by several families of human endogenous retroviruses (HERVs). The vast majority of LINE and HERV elements are densely methylated in normal somatic cells and contained in inactive chromatin. Methylation and chromatin structure together ensure a stable equilibrium between retroelements and their host. Hypomethylation and expression in developing germ cells opens a "window of opportunity" for retrotransposition and recombination that contribute to human evolution, but also inherited disease. In somatic cells, the presence of retroelements may be exploited to organize the genome into active and inactive regions, to separate domains and functional regions within one chromatin domain, to suppress transcriptional noise, and to regulate transcript stability. Retroelements, particularly ALUs, may also fulfill physiological roles during responses to stress and infections. Reactivation and hypomethylation of LINEs and HERVs may be important in the pathophysiology of cancer and various autoimmune diseases, contributing to chromosomal instability and chronically aberrant immune responses. The emerging insights into the pathophysiological importance of endogenous retroelements accentuate the gaps in our knowledge of how these elements are controlled in normal developing and mature cells.
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Affiliation(s)
- W A Schulz
- Urologische Klinik, Heinrich Heine Universität, Düsseldorf, Germany.
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Ejtehadi HD, Freimanis GL, Ali HA, Bowman S, Alavi A, Axford J, Callaghan R, Nelson PN. The potential role of human endogenous retrovirus K10 in the pathogenesis of rheumatoid arthritis: a preliminary study. Ann Rheum Dis 2006; 65:612-6. [PMID: 16192292 PMCID: PMC1798125 DOI: 10.1136/ard.2004.031146] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/07/2005] [Indexed: 11/03/2022]
Abstract
OBJECTIVE To examine whether human endogenous retrovirus K10 is associated with autoimmune rheumatic disease. DESIGN A novel multiplex reverse transcription polymerase chain reaction (RT-PCR) system was developed to investigate HERV-K10 mRNA expression in patients with rheumatoid arthritis. METHODS 40 patients with rheumatoid arthritis, 17 with osteoarthritis, and 27 healthy individuals were recruited and total RNA was extracted from peripheral blood mononuclear cells (PBMCs) and analysed using multiplex RT-PCR for the level of HERV-K10 gag mRNA expression. Southern blot and DNA sequencing confirmed the authenticity of the PCR products. RESULTS Using the histidyl tRNA synthetase (HtRNAS) gene as a housekeeping gene in the optimised multiplex RT-PCR, a significantly higher level of HERV-K10 gag mRNA expression was found in rheumatoid arthritis than in osteoarthritis (p = 0.01) or in the healthy controls (p = 0.02). CONCLUSION There is enhanced mRNA expression of the HERV-K10 gag region in rheumatoid arthritis compared with osteoarthritis or healthy controls. This could contribute to the pathogenesis of rheumatoid arthritis.
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Affiliation(s)
- H D Ejtehadi
- Molecular Immunology Research Group, Research Institute in Healthcare Sciences, University of Wolverhampton, Wulfruna Street, Wolverhampton WV1 1SB, UK.
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Machnik G, Sypniewski D, Wydmuch Z, Cholewa K, Mazurek U, Wilczok T, Smorag Z, Pacha J. Sequence analysis of proviral DNA of porcine endogenous retroviruses. Transplant Proc 2006; 37:4610-4. [PMID: 16387182 DOI: 10.1016/j.transproceed.2005.10.115] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2005] [Indexed: 11/21/2022]
Abstract
Among all species analyzed, the domestic pig seems to be the most appropriate organ donor for xenotransplantation. Porcine endogenous retroviruses (PERVs) are present in genomes of all pigs and are capable of infecting human cells in vitro thus posing a serious threat for xenotransplantation procedures. Despite the abundant distribution of PERVs integrated with porcine genome, the majority of PERV proviral DNA is not capable of expressing viral proteins unless seriously mutated. The aim of the study was to analyze PERV genome for mutations. The study was performed on blood samples from 146 pigs. Long-range polymerase chain reaction (Long-PCR) was performed with primer sets designed within long terminal repeats (LTRs). Long-PCR products of different molecular weights were obtained: 530 bp (33.1% of individuals), 580 bp (76.7%), 933 bp (100%), and 2900 bp (59.8%). Amplimers of 7200 bp were absent in 12.8% of individuals, indicating the lack of intact proviral DNA. Sequence analysis showed that most PERV proviral DNA was significantly mutated, thus suggesting the inability to express functional viral RNA; however, it cannot be ruled out that compensatory recombination processes could occur enabling replication of defective proviruses.
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Affiliation(s)
- G Machnik
- Department of Biotechnology and Genetic Engineering, Medical University of Silesia, Sosnowiec, Poland.
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30
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Kim HS, Yi JM, Hirai H, Huh JW, Jeong MS, Jang SB, Kim CG, Saitou N, Hyun BH, Lee WH. Human Endogenous Retrovirus (HERV)-R family in primates: Chromosomal location, gene expression, and evolution. Gene 2006; 370:34-42. [PMID: 16443335 DOI: 10.1016/j.gene.2005.11.008] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2005] [Revised: 10/31/2005] [Accepted: 11/02/2005] [Indexed: 11/24/2022]
Abstract
Hitherto, full-length endogenous retrovirus (HERV)-R has been located at human chromosome 7q11.2, and mRNA and envelope proteins have been detected in placenta and a variety of other cell types. In the present study, using a probe derived from the gorilla fosmid library, we detected the paralogous locus (7q31.3) of the HERV-R env gene in human chromosome 7q11.2, and also determined the chromosomal location in apes and Old World monkeys. The HERV-R gene was not detected in New World monkeys or prosimians with FISH and PCR analyses. We determined the sequences of the HERV-R env genes obtained from the genomic DNA of primates using PCR and sequencing tools. Except for a HERV-R env sequence derived from gorilla DNA, the functional domains of putative envelope proteins are conserved, suggesting that those domains could have a functional capacity in the primate genome. In addition, we investigated the env gene expression of HERV-R in various human tissues and cancer cells. An RT-PCR approach indicated that the env gene was expressed in several human tissues (brain, prostate, testis, kidney, placenta, thymus, and uterus) and cancer cells (RT4, BT-474, MCF7, OVCAR-3, LOX-IMVI, and AZ521). Taken together, our data could be of great use for understanding the evolutionary dynamics of HERV-R through primate radiation as well as the implications of its functional role in human tissues and cancers cells.
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Affiliation(s)
- Heui-Soo Kim
- Division of Biological Sciences, College of Natural Sciences, Pusan National University, Busan 609-735, Korea.
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Matousková M, Blazková J, Pajer P, Pavlícek A, Hejnar J. CpG methylation suppresses transcriptional activity of human syncytin-1 in non-placental tissues. Exp Cell Res 2006; 312:1011-20. [PMID: 16427621 DOI: 10.1016/j.yexcr.2005.12.010] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2005] [Revised: 12/06/2005] [Accepted: 12/13/2005] [Indexed: 11/20/2022]
Abstract
Syncytin-1 is a captive envelope glycoprotein encoded by one of human endogenous retroviruses W. It is expressed exclusively in the placental trophoblast where it participates in cell-to-cell fusion during differentiation of syncytiotrophobast. In other tissues, however, syncytin-1 expression must be kept in check because inadvertent cell fusion might be dangerous for tissue organization and integrity. We describe here an inverse correlation between CpG methylation of syncytin-1 5' long terminal repeat and its expression. Hypomethylation of the syncytin-1 5' long terminal repeat in the placenta and in the choriocarcinoma-derived cell line BeWo was detected. However, other analyzed primary cells and cell lines non-expressing syncytin-1 contain proviruses heavily methylated in this sequence. CpG methylation of syncytin-1 is resistant to the effect of the demethylating agent 5-azacytidine. The inhibitory role of CpG methylation is further confirmed by transient transfection of in-vitro-methylated syncytin-1 promoter-driven reporter construct. Altogether, we conclude that CpG methylation plays a principal role in the transcriptional suppression of syncytin-1 in non-placental tissues, and, in contrast, demethylation of the syncytin-1 promoter in trophoblast is a prerequisite for its expression and differentiation of multinucleated syncytiotrophoblast.
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Affiliation(s)
- Magda Matousková
- Department of Cellular and Viral Genetics, Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Flemingovo námìstí 2, 16637 Prague 6, Czech Republic
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Yi JM, Kim HM, Kim HS. Human endogenous retrovirus HERV-H family in human tissues and cancer cells: expression, identification, and phylogeny. Cancer Lett 2006; 231:228-39. [PMID: 16399224 DOI: 10.1016/j.canlet.2005.02.001] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2004] [Revised: 01/31/2005] [Accepted: 02/04/2005] [Indexed: 10/25/2022]
Abstract
HERV-H family is the most abundant HERV families in the human genome with more than 1000 copies including full-length, truncated form, and solitary LTRs. We investigated envelope (env) gene fragments of HERV-H family in various human tissues and cancer cells. The env fragments were detected in mRNA of several human tissues (placenta, skeletal muscle, spleen, and thymus) and cancer cells (RT4, BT-474, HCT-116, TE-1, UO-31, Jurkat, HepG2, A549, MCF7, OVCAR-3, MIA-PaCa-2, PC3, LOX-IMVI, AZ521, 2F7, U-937, and C-33A) by RT-PCR approach. The RT-PCR products were cloned and sequenced. New 12 clones from human tissues and 48 clones from cancer cells of env gene sequences belonging to the HERV-H family showed 84.3-98.1% sequence similarity to that of HERV-H (AF108843). Deduced amino acid sequences of 60 clones from human tissues and cancer cell lines showed multiple frameshifts and termination codons caused by deletion/insertion or point mutation with the exception of eight clones as following: HHE9-1, HHE9-5 (skeletal muscle), HHE10-5 (spleen), CHE10-9 (MCF7), CHE12-4, CHE12-5 (MIA-PaCa-2), and CHE18-1, CHE18-3 (C-33A) to that of HERV-H (AF108843). A phylogenetic tree of the HERV-H family was constructed to understand their relationship, indicating that they were divided into three groups, one major (group I) and two minor (group II and III), through sequence divergence. The HERV-H families in group I has been proliferated on human genome during hominoid evolution. These active HERV-H elements are worthy of further investigations as potential pathogenic effects to various human diseases including cancers.
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Affiliation(s)
- Joo-Mi Yi
- Division of Biological Sciences, College of Natural Sciences, Pusan National University, Pusan 609-735, South Korea
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Seifarth W, Frank O, Zeilfelder U, Spiess B, Greenwood AD, Hehlmann R, Leib-Mösch C. Comprehensive analysis of human endogenous retrovirus transcriptional activity in human tissues with a retrovirus-specific microarray. J Virol 2005; 79:341-52. [PMID: 15596828 PMCID: PMC538696 DOI: 10.1128/jvi.79.1.341-352.2005] [Citation(s) in RCA: 165] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Retrovirus-like sequences account for 8 to 9% of the human genome. Among these sequences, about 8,000 pol-containing proviral elements have been identified to date. As part of our ongoing search for active and possibly disease-relevant human endogenous retroviruses (HERVs), we have recently developed an oligonucleotide-based microarray. The assay allows for both the detection and the identification of most known retroviral reverse transcriptase (RT)-related nucleic acids in biological samples. In the present study, we have investigated the transcriptional activity of representative members of 20 HERV families in 19 different normal human tissues. Qualitative evaluation of chip hybridization signals and quantitative analysis by real-time RT-PCR revealed distinct HERV activity in the human tissues under investigation, suggesting that HERV elements are active in human cells in a tissue-specific manner. Most active members of HERV families were found in mRNA prepared from skin, thyroid gland, placenta, and tissues of reproductive organs. In contrast, only few active HERVs were detectable in muscle cells. Human tissues that lack HERV transcription could not be found, confirming that human endogenous retroviruses are permanent components of the human transcriptome. Distinct activity patterns may reflect the characteristics of the regulatory machinery in these cells, e.g., cell type-dependent occurrence of transcriptional regulatory factors.
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Affiliation(s)
- Wolfgang Seifarth
- Medical Clinic III, Faculty of Clinical Medicine Mannheim, University of Heidelberg, Mannheim, Germany.
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34
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Boonyaratanakornkit J, Chew A, Ryu DDY, Greenhalgh DG, Cho K. Murine endogenous retroviruses and their transcriptional potentials. Mamm Genome 2004; 15:914-23. [PMID: 15672595 DOI: 10.1007/s00335-004-2409-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Jerry Boonyaratanakornkit
- Biochemistry and Molecular Biology Graduate Group, University of California at Davis, Davis, California 95616, USA
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35
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Nelson PN, Hooley P, Roden D, Davari Ejtehadi H, Rylance P, Warren P, Martin J, Murray PG. Human endogenous retroviruses: transposable elements with potential? Clin Exp Immunol 2004; 138:1-9. [PMID: 15373898 PMCID: PMC1809191 DOI: 10.1111/j.1365-2249.2004.02592.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/06/2004] [Indexed: 12/20/2022] Open
Abstract
Human endogenous retroviruses (HERVs) are a significant component of a wider family of retroelements that constitute part of the human genome. These viruses, perhaps representative of previous exogenous retroviral infection, have been integrated and passed through successive generations within the germ line. The retention of HERVs and isolated elements, such as long-terminal repeats, could have the potential to harm. In this review we describe HERVs within the context of the family of known transposable elements and survey these viruses in terms of superantigens and molecular mimics. It is entirely possible that these mechanisms provide the potential for undesired immune responses.
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Affiliation(s)
- P N Nelson
- Research Institute in Healthcare Science, University of Wolverhampton, UK.
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Shen CH, Steiner LA. Genome structure and thymic expression of an endogenous retrovirus in zebrafish. J Virol 2004; 78:899-911. [PMID: 14694121 PMCID: PMC368747 DOI: 10.1128/jvi.78.2.899-911.2004] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2003] [Accepted: 10/03/2003] [Indexed: 11/20/2022] Open
Abstract
In a search for previously unknown genes that are required for lymphocyte development in zebrafish, a retroviral sequence was identified in a subtracted thymus cDNA library and in genomic DNA libraries. The provirus is 11.2 kb and contains intact open reading frames for the gag, pol, and env genes, as well as nearly identical flanking long terminal repeat sequences. As determined by in situ hybridization, the thymus appears to be a major tissue for retroviral expression in both larval and adult fish. Several viral transcripts were found by Northern blotting in the adult thymus. The provirus was found at the same genomic locus in sperm from four fish, suggesting that it is an endogenous retrovirus. Phylogenetic analysis indicates that it is closest to, yet distinct from, the cluster of murine leukemia virus-related retroviruses, suggesting that this virus represents a new group of retroviruses.
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Affiliation(s)
- Ching-Hung Shen
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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37
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Cho K, Pham T, Adamson L, Greenhalgh D. Regulation of murine endogenous retroviruses in the thymus after injury1,2. J Surg Res 2003; 115:318-24. [PMID: 14697300 DOI: 10.1016/s0022-4804(03)00230-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
We recently reported the induction of murine endogenous retroviruses (murine AIDS-related) in several distant organs of mice after burn injury. The regulation of endogenous retroviruses in response to burn injury was further investigated in the thymus. Female C57BLKS/J mice were subjected to 18% total body surface area flame burn injury. Thymus tissues collected at several time points (3 h to 7 days) were analyzed for the expression of subgenomic transcripts of murine endogenous retroviruses by RT-PCR. Interestingly, a novel 1.7-Kb subgenomic transcript and a recently described 1.1 Kb subgenomic transcript of murine endogenous retroviruses were transiently down-regulated in the thymus at day 1 after injury. The 1.7 Kb transcript has a coding potential for a truncated form of the envelope protein (total 214 amino acids) with a deletion of 418 amino acids near the C-terminus. The second transcript of 1.1 Kb has an open reading frame for the C-terminal transmembrane domain of the envelope protein including the p2E protein (R peptide). These data suggest the pathophysiologic effects of burn injury on the differential expression of murine endogenous retroviruses in the thymus after injury.
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Affiliation(s)
- Kiho Cho
- Shriners Hospitals for Children Northern California, University of California at Davis, Sacramento, California 95817, USA
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38
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Abstract
Endogenous retrovirus (ERV) sequences have been found in all mammals. In vitro and in vivo experiments revealed ERV activation and cross-species infection in several species. Sheep (Ovis aries) are used for various biotechnological purposes; however, they have not yet been comprehensively screened for ERV sequences. Therefore, the aim of the study was to classify the ERV sequences in the ovine genome (OERV) by analyzing the retroviral pro-pol sequences. Three OERV beta families and nine OERV gamma families were revealed. Novel open reading frames (ORF) in the amplified proviral fragment were found in one OERV beta family and two OERV gamma families. Hybrid OERV produced by putative recombination events were not detected. Quantitative analysis of the OERV sequences in the ovine genome revealed no relevant variations in the endogenous retroviral loads of different breeds. Expression analysis of different tissues from fetal and pregnant sheep detected mRNA from both gammaretrovirus families, showing ORF fragments. Thus, the release of retroviruses from sheep cells cannot be excluded.
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39
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Tanaka S, Ikeda H, Otsuka N, Yamamoto Y, Sugaya T, Yoshiki T. Tissue specific high level expression of a full length human endogenous retrovirus genome transgene, HERV-R, under control of its own promoter in rats. Transgenic Res 2003; 12:319-28. [PMID: 12779120 DOI: 10.1023/a:1023381819572] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Human endogenous retrovirus-R (HERV-R) is one of a full length HERV with a long open reading frame in the env region. The env transcripts are expressed in various human tissues. To investigate the biological role of HERV-R in vivo, we established two lines of transgenic rats carrying a full sequence of HERV-R under control of its own long terminal repeat (LTR) promoter. One line with tandem integration of multiple copies of the transgene expressed HERV-R mRNA in various organs with different expression levels and relatively higher in Harderian and submandibular salivary glands. In another line, the transgene was integrated as a single copy in a haploid and the expression was detected only in Harderian and submandibular salivary glands. In the placenta, one of the tissues with high levels of the HERV-R expression in humans, the transcription was evident starting the 12th day after gestation. A rabbit antiserum against synthetic peptides corresponding with the HERV-R env gene sequence led to detection of an 85 kDa product as a glycoprotein in the Harderian glands. While no pathological significance was observed in either line, the transgenic rat may prove to be a suitable model for analyzing the role of HERV-R function in vivo.
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Affiliation(s)
- Satoshi Tanaka
- Department of Pathology/Pathophysiology, Division of Pathophysiological Science, Hokkaido University Graduate School of Medicine, Kita-15, Nishi-7, Kita-ku, Sapporo 060-8638, Japan
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40
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Abstract
The concept of evolvability covers a broad spectrum of, often contradictory, ideas. At one end of the spectrum it is equivalent to the statement that evolution is possible, at the other end are untestable post hoc explanations, such as the suggestion that current evolutionary theory cannot explain the evolution of evolvability. We examine similarities and differences in eukaryote and prokaryote evolvability, and look for explanations that are compatible with a wide range of observations. Differences in genome organisation between eukaryotes and prokaryotes meets this criterion. The single origin of replication in prokaryote chromosomes (versus multiple origins in eukaryotes) accounts for many differences because the time to replicate a prokaryote genome limits its size (and the accumulation of junk DNA). Both prokaryotes and eukaryotes appear to switch from genetic stability to genetic change in response to stress. We examine a range of stress responses, and discuss how these impact on evolvability, particularly in unicellular organisms versus complex multicellular ones. Evolvability is also limited by environmental interactions (including competition) and we describe a model that places limits on potential evolvability. Examples are given of its application to predator competition and limits to lateral gene transfer. We suggest that unicellular organisms evolve largely through a process of metabolic change, resulting in biochemical diversity. Multicellular organisms evolve largely through morphological changes, not through extensive changes to cellular biochemistry.
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Affiliation(s)
- Anthony M Poole
- Allan Wilson Centre for Molecular Ecology and Evolution, Institute of Molecular BioSciences, Massey University, Private Bag 11222, Palmerston North, New Zealand.
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41
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Nelson PN, Carnegie PR, Martin J, Davari Ejtehadi H, Hooley P, Roden D, Rowland-Jones S, Warren P, Astley J, Murray PG. Demystified. Human endogenous retroviruses. Mol Pathol 2003; 56:11-8. [PMID: 12560456 PMCID: PMC1187282 DOI: 10.1136/mp.56.1.11] [Citation(s) in RCA: 131] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/19/2002] [Indexed: 12/11/2022]
Abstract
Human endogenous retroviruses (HERVs) are a family of viruses within our genome with similarities to present day exogenous retroviruses. HERVs have been inherited by successive generations and it is possible that some have conferred biological benefits. However, several HERVs have been implicated in certain cancers and autoimmune diseases. This article demystifies these retroviruses by providing an insight into HERVs, their means of classification, and a synopsis of HERVs implicated in cancer and autoimmunity. Furthermore, the biological roles of HERVs are explored.
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Affiliation(s)
- P N Nelson
- School of Applied Sciences, Division of Biomedical Science and Biosciences, University of Wolverhampton, Wolverhampton WV1 1SB, UK.
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42
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Andersson AC, Venables PJW, Tönjes RR, Scherer J, Eriksson L, Larsson E. Developmental expression of HERV-R (ERV3) and HERV-K in human tissue. Virology 2002; 297:220-5. [PMID: 12083821 DOI: 10.1006/viro.2002.1428] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The human endogenous retroviruses (HERVs), ERV3 (HERV-R) and HERV-K, are both known to be transcriptionally active in human placenta. In the case of ERV3 there is also indirect evidence for its participation in cellular differentiation. In this study we examined the expression of ERV3 (HERV-R) and HERV-K in human normal fetal tissues by in situ hybridization. The highest level of ERV3 env expression was detected in primitive adrenal cortex. Elevated levels of expression were also found in the following developing tissues: kidneys (tubules), tongue, heart, liver, and central nervous system. Tissue-specific expression was found for HERV-K rec (former cORF) but not for pol/int transcripts. The highest rec expression was found in placenta and levels slightly higher than sense control were found in the rest of the tissues examined. Pol/Int was not possible to quantitate. It appears that ERV3 is expressed in an organ-specific way during embryogenesis and might suggest a possible role in the development and differentiation of human tissues.
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43
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Strísovský K, Smrz D, Fehrmann F, Kräusslich HG, Konvalinka J. The murine endogenous retrovirus MIA14 encodes an active aspartic proteinase that is functionally similar to proteinases from D-type retroviruses. Arch Biochem Biophys 2002; 398:261-8. [PMID: 11831858 DOI: 10.1006/abbi.2001.2728] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Murine intracisternal A-type particles (IAPs) are endogenous retroviruses showing sequence homologies to B/D- and avian C-type retroviruses and a gene expression strategy similar to that of D-type retroviruses. These viruses form immature particles in the endoplasmic reticulum and do not release extracellular virions, but are competent for retrotransposition within the virus-producing cell. It had been assumed that lack of polyprotein processing and maturation is due to a defect in the viral proteinase (PR), but recent experiments have shown that polyprotein processing occurs when assembly of the mouse IAP MIA14 is artificially directed to the plasma membrane. We have expressed and purified recombinant MIA14 PR and show that it undergoes N- and C-terminal autoprocessing at defined sites. Using peptide cleavage and inhibition assays and in vitro cleavage of recombinant HIV-1 and MIA14 Gag polyproteins, we show that MIA14 PR is a catalytically competent enzyme comparable in its efficiency to PRs from type D exogenous retroviruses. MIA14 PR is related to the PR of Mason-Pfizer monkey virus both functionally and with respect to its expression strategy, and is distinct from HIV-1 PR with respect to substrate specificity and catalytic efficiency. These findings reveal a functional and possibly evolutionary relationship between MIA14 and D-type retroviruses and imply that a functional PR may be relevant for intracellular retrotransposition even in the case of an endogenous retrovirus that does not produce extracellular virus.
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Affiliation(s)
- Kvido Strísovský
- Department of Biochemistry, Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo nám. 2, Praha 6, 166 10, Czech Republic.
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44
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Johnston JB, Silva C, Holden J, Warren KG, Clark AW, Power C. Monocyte activation and differentiation augment human endogenous retrovirus expression: implications for inflammatory brain diseases. Ann Neurol 2001; 50:434-42. [PMID: 11601494 DOI: 10.1002/ana.1131] [Citation(s) in RCA: 149] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Human endogenous retroviruses (HERVs) have been implicated as causative agents in diseases characterized by inflammation and macrophage activation, such as multiple sclerosis. Because monocyte activation and differentiation influence retroviral transcription and replication, we investigated the contribution of these processes to the expression of four HERV families (HERV-W, HERV-K, HERV-E, and HERV-H) in human monocytes, and autopsied brain tissue from patients with brain diseases associated with increased macrophage activity. Reverse transcriptase-polymerase chain reaction analysis of primary macrophages and U937 monocytoid cells stimulated with phorbol-12-myristate-13-acetate or lipopolysaccharide revealed three- to ninefold increases in HERV-W, HERV-K, and HERV-H RNA levels. In addition, elevated reverse transcriptase activity and HERV RNA were detectable in supernatants from PMA-stimulated U937 cultures, properties that could be attenuated with the inhibitor of monocyte differentiation threonine-lysine-proline. In contrast, stimulation of monocytes decreased or had no effect on HERV-E expression. Compared with controls, HERV-W and HERV-K expression was increased in brain tissue from patients with multiple sclerosis or human immunodeficiency virus infection or AIDS, with concomitant elevated tumor necrosis factor-alpha levels. Similarly, elevated HERV-W levels were detected in patients with Alzheimer's dementia only when tumor necrosis factor-alpha expression was also evident (2 of 6 cases). The detection of several HERVs in inflammatory brain diseases and the capacity to augment HERV expression in monocytes with compounds that influence cellular activity suggest that increased expression of these viruses is a consequence of increased immune activity rather than causative of distinct diseases.
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Affiliation(s)
- J B Johnston
- Department of Clinical Neurosciences, University of Calgary, Alberta, Canada
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45
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Kuhelj R, Rizzo CJ, Chang CH, Jadhav PK, Towler EM, Korant BD. Inhibition of human endogenous retrovirus-K10 protease in cell-free and cell-based assays. J Biol Chem 2001; 276:16674-82. [PMID: 11278433 DOI: 10.1074/jbc.m008763200] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A full-length and C-terminally truncated version of human endogenous retrovirus (HERV)-K10 protease were expressed in Escherichia coli and purified to homogeneity. Both versions of the protease efficiently processed HERV-K10 Gag polyprotein substrate. HERV-K10 Gag was also cleaved by human immunodeficiency virus, type 1 (HIV-1) protease, although at different sites. To identify compounds that could inhibit protein processing dependent on the HERV-K10 protease, a series of cyclic ureas that had previously been shown to inhibit HIV-1 protease was tested. Several symmetric bisamides acted as very potent inhibitors of both the truncated and full-length form of HERV-K10 protease, in subnanomolar or nanomolar range, respectively. One of the cyclic ureas, SD146, can inhibit the processing of in vitro translated HERV-K10 Gag polyprotein substrate by HERV-K10 protease. In addition, in virus-like particles isolated from the teratocarcinoma cell line NCCIT, there is significant accumulation of Gag and Gag-Pol precursors upon treatment with SD146, suggesting the compound efficiently blocks HERV-K Gag processing in cells. This is the first report of an inhibitor able to block cell-associated processing of Gag polypeptides of an endogenous retrovirus.
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Affiliation(s)
- R Kuhelj
- Department of Virology, Experimental Station, DuPont Pharmaceuticals, Wilmington, Delaware 19880, USA
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46
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Ericsson T, Oldmixon B, Blomberg J, Rosa M, Patience C, Andersson G. Identification of novel porcine endogenous betaretrovirus sequences in miniature swine. J Virol 2001; 75:2765-70. [PMID: 11222699 PMCID: PMC115900 DOI: 10.1128/jvi.75.6.2765-2770.2001] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
PCR amplification of genomic DNA from miniature swine peripheral blood lymphocytes, using primers corresponding to highly conserved regions of the polymerase (pol) gene, allowed the identification of two novel porcine endogenous retrovirus (PERV) sequences, PMSN-1 and PMSN-4. Phylogenetic analyses of the nucleotide sequences of PMSN-1 and PMSN-4 revealed them to be most closely related to betaretroviruses. The identification of PERVs belonging to the Betaretrovirus genus shows that endogenous retroviruses of this family are more broadly represented in mammalian species than previously appreciated. Both sequences contained inactivating mutations, implying that these particular loci are defective. However, Southern blot analysis showed additional copies of closely related proviruses in the miniature swine genome. Analyses of fetal and adult miniature swine tissues revealed a broad mRNA expression pattern of both PMSN-1 and PMSN-4. The most abundant expression was detected in whole bone marrow c-kit(+) (CD117(+)) progenitor bone marrow cells, fetal liver, salivary gland, and thymus. It appears unlikely that functional loci encoding these novel PERV sequences exist, but this remains to be established. The betaretrovirus sequences described in this report will allow such investigations to be actively pursued.
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MESH Headings
- Animals
- Blotting, Southern
- DNA, Viral/genetics
- Endogenous Retroviruses/classification
- Endogenous Retroviruses/genetics
- Gene Products, pol/genetics
- Genes, pol
- Genome
- Genome, Viral
- Humans
- Leukocytes, Mononuclear/virology
- Mice
- Molecular Sequence Data
- Phylogeny
- Polymerase Chain Reaction
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Sequence Analysis, DNA
- Swine, Miniature/virology
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Affiliation(s)
- T Ericsson
- BioTransplant, Inc., Charlestown, Massachusetts 02129, USA
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47
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Abstract
The remarkable similarity among the genomes of humans and the African great apes could warrant their classification together as a single genus. However, whereas there are many similarities in the biology, life history, and behavior of humans and great apes, there are also many striking differences that need to be explained. The complete sequencing of the human genome creates an opportunity to ask which genes are involved in those differences. A logical approach would be to use the chimpanzee genome for comparison and the other great ape genomes for confirmation. Until such a great ape genome project can become reality, the next best approach must be educated guesses of where the genetic differences may lie and a careful analysis of differences that we do know about. Our group recently discovered a human-specific inactivating mutation in the CMP-sialic acid hydroxylase gene, which results in the loss of expression of a common mammalian cell-surface sugar throughout all cells in the human body. We are currently investigating the implications of this difference for a variety of issues relevant to humans, ranging from pathogen susceptibility to brain development. Evaluating the uniqueness of this finding has also led us to explore the existing literature on the broader issue of genetic differences between humans and great apes. The aim of this brief review is to consider a listing of currently known genetic differences between humans and great apes and to suggest avenues for future research. The differences reported between human and great ape genomes include cytogenetic differences, differences in the type and number of repetitive genomic DNA and transposable elements, abundance and distribution of endogenous retroviruses, the presence and extent of allelic polymorphisms, specific gene inactivation events, gene sequence differences, gene duplications, single nucleotide polymorphisms, gene expression differences, and messenger RNA splicing variations. Evaluation of the reported findings in all these categories indicates that the CMP-sialic hydroxylase mutation is the only one that has so far been shown to result in a global biochemical and structural difference between humans and great apes. Several of the other known genetic dissimilarities deserve more exploration at the functional level. Among the areas of focus for the future should be genes affecting development, mental maturation, reproductive biology, and other aspects of life history. The approaches taken should include both going from the genome up to the adaptive potential of the organisms and going from novel adaptive regimes down to the relevant repercussions in the genome. Also, as much as we desire a simple genetic explanation for the human phenomenon, it is much more probable that our evolution occurred in multiple genetic steps, many of which must have left detectable footprints in our genomes. Ultimately, we need to know the exact number of genetic steps, the order in which they occurred, and the temporal, spatial, environmental, and cultural contexts that determined their impact on human evolution.
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Affiliation(s)
- P Gagneux
- Department of Medicine and Glycobiology Research and Training Center, University of California at San Diego, La Jolla, California 92093-0687, USA
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48
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Abstract
The human genome is rife with the proviral remains of many ancient retroviruses. The past year has seen significant progress in understanding the structure, distribution and potential function of many of these elements. Although hypotheses concerning the potential effects of these elements are common, however, incisive experiments to test any functions remain much less so.
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Affiliation(s)
- M Bock
- Division of Virology, National Institute for Medical Research, The Ridgeway, London NW7 1AA, UK
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49
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Abstract
Presence of transposable elements (TEs) in the human genome has profound effects on genome function, structure and evolution. TE mobility and inter-TE recombination are the origin of a large spectrum of mutations and genome reorganization leading to diseases. From the data provided by the Human Genome Project and from information on the detection and dynamics of TEs within and between species acquired during the last two decades, we now know that these elements are not only involved in mutagenesis but can also participate in many cellular functions including recombination, gene regulation, protein-coding RNA messages and, possibly, cellular stress response and centromere function. TEs also promote a general genome shuffling process that has been important for the evolution of several gene families and for the development of new regulatory pathways.
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Affiliation(s)
- J M Deragon
- Biomove, Centre National de la Recherche Scientifique - UMR 6547, University Blaise-Pascal Aubière, Gif-sur-Yvette, France
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50
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Domansky AN, Kopantzev EP, Snezhkov EV, Lebedev YB, Leib-Mosch C, Sverdlov ED. Solitary HERV-K LTRs possess bi-directional promoter activity and contain a negative regulatory element in the U5 region. FEBS Lett 2000; 472:191-5. [PMID: 10788609 DOI: 10.1016/s0014-5793(00)01460-5] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Reporter gene analysis of HERV-K solitary long terminal repeats (LTRs) showed that they retain detectable activity in human teratocarcinoma cells, and can direct the transcription in both orientations relative to the reporter gene. Deletion analysis demonstrated the possible existence of alternative promoters within the LTR as well as a silencer-like element in the U5 region. Our results indicate also that all-trans-retinoic acid is capable of modulating expression of the reporter gene directed by a HERV-K LTR in NT2/D1 cells.
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Affiliation(s)
- A N Domansky
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya 16/10, Moscow, Russia
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