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Li F, Karlsson H. Expression and regulation of human endogenous retrovirus W elements. APMIS 2016; 124:52-66. [PMID: 26818262 DOI: 10.1111/apm.12478] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Accepted: 10/12/2015] [Indexed: 01/06/2023]
Abstract
Human endogenous retroviruses (HERV) comprise 8% of the human genome and can be classified into at least 31 families. A typical HERV provirus consists of internal gag, pol and env genes, flanked by two long terminal repeats (LTRs). No single provirus is capable of engendering infectious particles. HERV are by nature repetitive and have with few notable exceptions lost their protein-coding capacity. Therefore, HERV have consistently been excluded from array-based expression studies and hence little is known of their expression, regulation, and potential functional significance. An increasing number of studies have, however, observed expression of the W family of HERV in various human tissues and cells, predominantly in placenta. HERV-W LTRs act as promoters in directing transcription of HERV-W members, contribute to their tissue-specific and highly diversified expression pattern. Furthermore, leaky transcription originating from adjacent genes plays a role in the transcription initiation of HERV-W psudoelements. It has been reported that HERV-W elements, including ERVWE1 (the so far only known HERV-W locus harboring a gene (env) functionally adopted by the human host to critically participate in placenta biogenesis), can become transactivated in a range of human non-placental cell-lines during exogenous virus infections. Aberrant expression of HERV-W has been associated with human diseases, such as cancer, multiple sclerosis, and schizophrenia. Based on published reports, transcriptional activities of HERV-W appear to be influenced by several mechanisms; binding of transcription factors to LTR promoters and enhancers outside of LTRs, genetic variation and alteration in DNA methylation and histone modification. Emerging mechanistic studies support the notion that HERV-W represents a potential marker or mediator of environmental exposures (e.g., virus infection) in the development of chronic complex diseases.
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Affiliation(s)
- Fang Li
- Department of Basic Medical Science, Changsha Medical University, Changsha, China.,Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Håkan Karlsson
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
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Bastida-Ruiz D, Van Hoesen K, Cohen M. The Dark Side of Cell Fusion. Int J Mol Sci 2016; 17:E638. [PMID: 27136533 PMCID: PMC4881464 DOI: 10.3390/ijms17050638] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2016] [Revised: 04/14/2016] [Accepted: 04/22/2016] [Indexed: 12/17/2022] Open
Abstract
Cell fusion is a physiological cellular process essential for fertilization, viral entry, muscle differentiation and placental development, among others. In this review, we will highlight the different cancer cell-cell fusions and the advantages obtained by these fusions. We will specially focus on the acquisition of metastatic features by cancer cells after fusion with bone marrow-derived cells. The mechanism by which cancer cells fuse with other cells has been poorly studied thus far, but the presence in several cancer cells of syncytin, a trophoblastic fusogen, leads us to a cancer cell fusion mechanism similar to the one used by the trophoblasts. The mechanism by which cancer cells perform the cell fusion could be an interesting target for cancer therapy.
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Affiliation(s)
- Daniel Bastida-Ruiz
- Department of Gynecology Obstetrics, Faculty of Medicine, University of Geneva, Geneva 1211, Switzerland.
| | - Kylie Van Hoesen
- Department of Gynecology Obstetrics, Faculty of Medicine, University of Geneva, Geneva 1211, Switzerland.
| | - Marie Cohen
- Department of Gynecology Obstetrics, Faculty of Medicine, University of Geneva, Geneva 1211, Switzerland.
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Buslei R, Strissel PL, Henke C, Schey R, Lang N, Ruebner M, Stolt CC, Fabry B, Buchfelder M, Strick R. Activation and regulation of endogenous retroviral genes in the human pituitary gland and related endocrine tumours. Neuropathol Appl Neurobiol 2015; 41:180-200. [PMID: 24635849 DOI: 10.1111/nan.12136] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2013] [Accepted: 03/10/2014] [Indexed: 12/29/2022]
Abstract
AIMS Adenohypophysis (AH) hormone-producing cells represent the origin of diverse groups of pituitary adenomas (PA). Deregulation of hypothalamic hormone receptors, growth factors and cAMP signalling have been implicated in the aetiology of PA. Endogenous retroviruses (ERVs) are derived from past exogenous retroviral infections and represent more than 8% of the human genome. Some ERV genes encode open reading frames and produce functional proteins, for example, the ERVW-1 envelope gene Syncytin-1, essential for placentogenesis, but also deregulated in human tumours. Data concerning ERV expression in the AH and related endocrine tumours are missing. METHODS Syncytin-1 protein was analysed in normal AH (n = 15) and compared with five PA subtypes (n = 117) by immunohistochemistry. Absolute gene expression of 20 ERV functional envelope genes and ERVW-5 gag was measured. PA tissues were examined for Syncytin-1 and the cAMP signalling marker phospho-CREB-Ser133 using immunohistochemistry. Isolated primary human PA cells were treated with different hormones. Murine embryonic and adult pituitary gland ERV expressions were compared with human AH. RESULTS Syncytin-1 protein colocalized with corticotropic cells of AH. In contrast, all PA demonstrated significant Syncytin-1 protein overexpression, supporting deregulation. All other ERV genes showed significant up-regulations in different PA subtypes. Phospho-CREB-Ser133 and Syncytin-1 colocalized in PA cells. Cultivated primary PA cells with ACTH or CRH induced their respective receptors and ERV genes. Syncytin-A/-B, murine orthologues to human Syncytin-1/-2, localized to embryonic and adult pituitary glands demonstrating functional mammalian conservation. CONCLUSIONS Deregulated ERV genes may contribute to PA development via cAMP signalling.
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Affiliation(s)
- Rolf Buslei
- Institute of Neuropathology, University-Clinic Erlangen, Lab for Molecular Medicine, Erlangen, Germany
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Suntsova M, Garazha A, Ivanova A, Kaminsky D, Zhavoronkov A, Buzdin A. Molecular functions of human endogenous retroviruses in health and disease. Cell Mol Life Sci 2015; 72:3653-75. [PMID: 26082181 PMCID: PMC11113533 DOI: 10.1007/s00018-015-1947-6] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2015] [Revised: 05/29/2015] [Accepted: 06/03/2015] [Indexed: 12/13/2022]
Abstract
Human endogenous retroviruses (HERVs) and related genetic elements form 504 distinct families and occupy ~8% of human genome. Recent success of high-throughput experimental technologies facilitated understanding functional impact of HERVs for molecular machinery of human cells. HERVs encode active retroviral proteins, which may exert important physiological functions in the body, but also may be involved in the progression of cancer and numerous human autoimmune, neurological and infectious diseases. The spectrum of related malignancies includes, but not limits to, multiple sclerosis, psoriasis, lupus, schizophrenia, multiple cancer types and HIV. In addition, HERVs regulate expression of the neighboring host genes and modify genomic regulatory landscape, e.g., by providing regulatory modules like transcription factor binding sites (TFBS). Indeed, recent bioinformatic profiling identified ~110,000 regulatory active HERV elements, which formed at least ~320,000 human TFBS. These and other peculiarities of HERVs might have played an important role in human evolution and speciation. In this paper, we focus on the current progress in understanding of normal and pathological molecular niches of HERVs, on their implications in human evolution, normal physiology and disease. We also review the available databases dealing with various aspects of HERV genetics.
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Affiliation(s)
- Maria Suntsova
- Group for Genomic Regulation of Cell Signaling Systems, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Moscow, 117997, Russia.
- Laboratory of Bioinformatics, D. Rogachyov Federal Research Center of Pediatric Hematology, Oncology and Immunology, Moscow, 117198, Russia.
| | - Andrew Garazha
- Group for Genomic Regulation of Cell Signaling Systems, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Moscow, 117997, Russia.
- Laboratory of Bioinformatics, D. Rogachyov Federal Research Center of Pediatric Hematology, Oncology and Immunology, Moscow, 117198, Russia.
| | - Alena Ivanova
- Group for Genomic Regulation of Cell Signaling Systems, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Moscow, 117997, Russia.
- Pathway Pharmaceuticals, Wan Chai, Hong Kong, Hong Kong SAR.
| | - Dmitry Kaminsky
- Pathway Pharmaceuticals, Wan Chai, Hong Kong, Hong Kong SAR.
| | - Alex Zhavoronkov
- Pathway Pharmaceuticals, Wan Chai, Hong Kong, Hong Kong SAR.
- Department of Translational and Regenerative Medicine, Moscow Institute of Physics and Technology, 9 Institutskiy per., Dolgoprudny, Moscow, 141700, Russia.
| | - Anton Buzdin
- Group for Genomic Regulation of Cell Signaling Systems, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Moscow, 117997, Russia.
- Pathway Pharmaceuticals, Wan Chai, Hong Kong, Hong Kong SAR.
- National Research Centre "Kurchatov Institute", Centre for Convergence of Nano-, Bio-, Information and Cognitive Sciences and Technologies, 1, Akademika Kurchatova sq., Moscow, 123182, Russia.
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Chiappinelli KB, Strissel PL, Desrichard A, Li H, Henke C, Akman B, Hein A, Rote NS, Cope LM, Snyder A, Makarov V, Budhu S, Buhu S, Slamon DJ, Wolchok JD, Pardoll DM, Beckmann MW, Zahnow CA, Merghoub T, Mergoub T, Chan TA, Baylin SB, Strick R. Inhibiting DNA Methylation Causes an Interferon Response in Cancer via dsRNA Including Endogenous Retroviruses. Cell 2015; 162:974-86. [PMID: 26317466 PMCID: PMC4556003 DOI: 10.1016/j.cell.2015.07.011] [Citation(s) in RCA: 1203] [Impact Index Per Article: 133.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Revised: 05/04/2015] [Accepted: 06/26/2015] [Indexed: 12/18/2022]
Abstract
We show that DNA methyltransferase inhibitors (DNMTis) upregulate immune signaling in cancer through the viral defense pathway. In ovarian cancer (OC), DNMTis trigger cytosolic sensing of double-stranded RNA (dsRNA) causing a type I interferon response and apoptosis. Knocking down dsRNA sensors TLR3 and MAVS reduces this response 2-fold and blocking interferon beta or its receptor abrogates it. Upregulation of hypermethylated endogenous retrovirus (ERV) genes accompanies the response and ERV overexpression activates the response. Basal levels of ERV and viral defense gene expression significantly correlate in primary OC and the latter signature separates primary samples for multiple tumor types from The Cancer Genome Atlas into low versus high expression groups. In melanoma patients treated with an immune checkpoint therapy, high viral defense signature expression in tumors significantly associates with durable clinical response and DNMTi treatment sensitizes to anti-CTLA4 therapy in a pre-clinical melanoma model.
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Affiliation(s)
- Katherine B Chiappinelli
- Department of Oncology, The Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Baltimore, MD 21287, USA
| | - Pamela L Strissel
- Department of Gynaecology and Obstetrics, Laboratory for Molecular Medicine, University-Clinic Erlangen, 91054 Erlangen, Germany
| | - Alexis Desrichard
- Human Oncology and Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Huili Li
- Department of Oncology, The Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Baltimore, MD 21287, USA
| | - Christine Henke
- Department of Gynaecology and Obstetrics, Laboratory for Molecular Medicine, University-Clinic Erlangen, 91054 Erlangen, Germany
| | - Benjamin Akman
- Department of Oncology, The Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Baltimore, MD 21287, USA
| | - Alexander Hein
- Department of Gynaecology and Obstetrics, Laboratory for Molecular Medicine, University-Clinic Erlangen, 91054 Erlangen, Germany
| | - Neal S Rote
- Department of Reproductive Biology, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Leslie M Cope
- Department of Oncology, The Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Baltimore, MD 21287, USA
| | - Alexandra Snyder
- Human Oncology and Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA; Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Vladimir Makarov
- Human Oncology and Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | | | - Sadna Buhu
- Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Dennis J Slamon
- The Jonsson Comprehensive Cancer Center, University of California-Los Angeles, Los Angeles, CA 90095, USA
| | - Jedd D Wolchok
- Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Drew M Pardoll
- Department of Oncology, The Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Baltimore, MD 21287, USA
| | - Matthias W Beckmann
- Department of Gynaecology and Obstetrics, Laboratory for Molecular Medicine, University-Clinic Erlangen, 91054 Erlangen, Germany
| | - Cynthia A Zahnow
- Department of Oncology, The Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Baltimore, MD 21287, USA
| | | | - Taha Mergoub
- Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Timothy A Chan
- Human Oncology and Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA; Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Stephen B Baylin
- Department of Oncology, The Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Baltimore, MD 21287, USA.
| | - Reiner Strick
- Department of Gynaecology and Obstetrics, Laboratory for Molecular Medicine, University-Clinic Erlangen, 91054 Erlangen, Germany.
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Frese S, Ruebner M, Suhr F, Konou TM, Tappe KA, Toigo M, Jung HH, Henke C, Steigleder R, Strissel PL, Huebner H, Beckmann MW, van der Keylen P, Schoser B, Schiffer T, Frese L, Bloch W, Strick R. Long-Term Endurance Exercise in Humans Stimulates Cell Fusion of Myoblasts along with Fusogenic Endogenous Retroviral Genes In Vivo. PLoS One 2015; 10:e0132099. [PMID: 26154387 PMCID: PMC4495930 DOI: 10.1371/journal.pone.0132099] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2015] [Accepted: 06/10/2015] [Indexed: 11/21/2022] Open
Abstract
Myogenesis is defined as growth, differentiation and repair of muscles where cell fusion of myoblasts to multinucleated myofibers is one major characteristic. Other cell fusion events in humans are found with bone resorbing osteoclasts and placental syncytiotrophoblasts. No unifying gene regulation for natural cell fusions has been found. We analyzed skeletal muscle biopsies of competitive cyclists for muscle-specific attributes and expression of human endogenous retrovirus (ERV) envelope genes due to their involvement in cell fusion of osteoclasts and syncytiotrophoblasts. Comparing muscle biopsies from post- with the pre-competitive seasons a significant 2.25-fold increase of myonuclei/mm fiber, a 2.38-fold decrease of fiber area/nucleus and a 3.1-fold decrease of satellite cells (SCs) occurred. We propose that during the pre-competitive season SC proliferation occurred following with increased cell fusion during the competitive season. Expression of twenty-two envelope genes of muscle biopsies demonstrated a significant increase of putative muscle-cell fusogenic genes Syncytin-1 and Syncytin-3, but also for the non-fusogenic erv3. Immunohistochemistry analyses showed that Syncytin-1 mainly localized to the sarcolemma of myofibers positive for myosin heavy-chain isotypes. Cellular receptors SLC1A4 and SLC1A5 of Syncytin-1 showed significant decrease of expression in post-competitive muscles compared with the pre-competitive season, but only SLC1A4 protein expression localized throughout the myofiber. Erv3 protein was strongly expressed throughout the myofiber, whereas envK1-7 localized to SC nuclei and myonuclei. Syncytin-1 transcription factors, PPARγ and RXRα, showed no protein expression in the myofiber, whereas the pCREB-Ser133 activator of Syncytin-1 was enriched to SC nuclei and myonuclei. Syncytin-1, Syncytin-3, SLC1A4 and PAX7 gene regulations along with MyoD1 and myogenin were verified during proliferating or actively-fusing human primary myoblast cell cultures, resembling muscle biopsies of cyclists. Myoblast treatment with anti-Synycytin-1 abrogated cell fusion in vitro. Our findings support functional roles for ERV envelope proteins, especially Syncytin-1, contributing to cell fusion of myotubes.
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Affiliation(s)
- Sebastian Frese
- Institute of Cardiovascular Research and Sport Medicine, Department of Molecular and Cellular Sport Medicine, German Sport University Cologne, Am Sportpark Muengersdorf, Cologne, Germany
- University Hospital Zurich, Department of Neurology, Frauenklinikstrasse, Zurich, Switzerland
- Institute of Human Movement Sciences and Sport, Exercise Physiology, ETH Zurich, Winterthurerstrasse, Zurich, Switzerland
| | - Matthias Ruebner
- Friedrich-Alexander University Erlangen-Nürnberg, University-Clinic Erlangen, Department of Gynaecology and Obstetrics, Laboratory for Molecular Medicine, Erlangen, Universitaetsstrasse, Erlangen, Germany
| | - Frank Suhr
- Institute of Cardiovascular Research and Sport Medicine, Department of Molecular and Cellular Sport Medicine, German Sport University Cologne, Am Sportpark Muengersdorf, Cologne, Germany
| | - Thierry M. Konou
- Institute of Cardiovascular Research and Sport Medicine, Department of Molecular and Cellular Sport Medicine, German Sport University Cologne, Am Sportpark Muengersdorf, Cologne, Germany
| | - Kim A. Tappe
- Institute of Cardiovascular Research and Sport Medicine, Department of Molecular and Cellular Sport Medicine, German Sport University Cologne, Am Sportpark Muengersdorf, Cologne, Germany
| | - Marco Toigo
- Institute of Human Movement Sciences and Sport, Exercise Physiology, ETH Zurich, Winterthurerstrasse, Zurich, Switzerland
- University of Zurich, Balgrist University Hospital, Department of Orthopaedics, Forchstrasse, Zurich, Switzerland
| | - Hans H. Jung
- University Hospital Zurich, Department of Neurology, Frauenklinikstrasse, Zurich, Switzerland
| | - Christine Henke
- Friedrich-Alexander University Erlangen-Nürnberg, University-Clinic Erlangen, Department of Gynaecology and Obstetrics, Laboratory for Molecular Medicine, Erlangen, Universitaetsstrasse, Erlangen, Germany
| | - Ruth Steigleder
- Friedrich-Alexander University Erlangen-Nürnberg, University-Clinic Erlangen, Department of Gynaecology and Obstetrics, Laboratory for Molecular Medicine, Erlangen, Universitaetsstrasse, Erlangen, Germany
| | - Pamela L. Strissel
- Friedrich-Alexander University Erlangen-Nürnberg, University-Clinic Erlangen, Department of Gynaecology and Obstetrics, Laboratory for Molecular Medicine, Erlangen, Universitaetsstrasse, Erlangen, Germany
| | - Hanna Huebner
- Friedrich-Alexander University Erlangen-Nürnberg, University-Clinic Erlangen, Department of Gynaecology and Obstetrics, Laboratory for Molecular Medicine, Erlangen, Universitaetsstrasse, Erlangen, Germany
| | - Matthias W. Beckmann
- Friedrich-Alexander University Erlangen-Nürnberg, University-Clinic Erlangen, Department of Gynaecology and Obstetrics, Laboratory for Molecular Medicine, Erlangen, Universitaetsstrasse, Erlangen, Germany
| | - Piet van der Keylen
- Institute of Anatomy, Friedrich-Alexander University of Erlangen-Nürnberg, Krankenhausstrasse, Erlangen, Germany
| | - Benedikt Schoser
- Ludwig Maximilian University Munich, Department of Neurology, Friedrich Baur Institute, Ziemssenstrasse, Munich, Germany
| | - Thorsten Schiffer
- German Sport University Cologne, Outpatient Clinic for Sports Traumatology and Public Health Consultation, Am Sportpark Muengersdorf, Cologne, Germany
| | - Laura Frese
- University Hospital and University Zurich, Division of Surgical Research, Raemistrasse, Zurich, Switzerland
| | - Wilhelm Bloch
- Institute of Cardiovascular Research and Sport Medicine, Department of Molecular and Cellular Sport Medicine, German Sport University Cologne, Am Sportpark Muengersdorf, Cologne, Germany
- The German Research Centre of Elite Sport, German Sport University Cologne, Am Sportpark Muengersdorf, Cologne, Germany
| | - Reiner Strick
- Friedrich-Alexander University Erlangen-Nürnberg, University-Clinic Erlangen, Department of Gynaecology and Obstetrics, Laboratory for Molecular Medicine, Erlangen, Universitaetsstrasse, Erlangen, Germany
- * E-mail:
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Lu Q, Li J, Senkowski C, Tang Z, Wang J, Huang T, Wang X, Terry K, Brower S, Glasgow W, Chen H, Jiang SW. Promoter Hypermethylation and Decreased Expression of Syncytin-1 in Pancreatic Adenocarcinomas. PLoS One 2015; 10:e0134412. [PMID: 26230721 PMCID: PMC4521816 DOI: 10.1371/journal.pone.0134412] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Accepted: 07/08/2015] [Indexed: 02/05/2023] Open
Abstract
Syncytin-1 is a member of human endogenous retroviral W gene family (HERVW1). Known to be expressed in human placental trophoblast, syncytin-1 protein mediates the fusion of cytotrophoblasts for the formation of syncytiotrophoblasts, the terminally differentiated form of trophoblast lineage. In addition, in vitro studies indicate that syncytin-1 possessed nonfusogenic functions such as those for immune suppression, cell cycle regulation and anti-apoptotic activities. Overexpression of syncytin-1 has been observed in various malignant tissues including breast, endometrial and ovarian cancers. It was reported that syncytin-1 gene expression is associated with dynamic changes of DNA hypomethylation in the 5' LTR. In this study, applying the real-time PCR, Western blot analysis and immunohistochemistry methods, we demonstrate a constitutive expression of syncytin-1 in normal pancreas tissues as well as normal tissues adjacent to cancer lesions. Moreover, a reduced expression is found in the pancreatic adenocarcinoma tissues. The expression levels of syncytin-1 are not correlated with the stage, historical grade and gender, but inversely correlated with patients' age. Furthermore, COBRA and bisulfite sequencing results indicated that the lower expression of syncytin-1 is correlated with the hypermethylation of two CpG dinucleotides in the 5' LTR of syncytin-1 gene. The nonfusogenic function of syncytin-1 in normal pancreas as well as its role(s) in the pathogenesis and progression of pancreatic cancers remains to be investigated. Identification of the two CpG dinucleotides around transcription start site as key epigenetic elements has provided valuable information for further studies on the epigenetic regulation of syncytin-1 in pancreatic cancer cells.
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Affiliation(s)
- Qinsheng Lu
- Department of Histology and Embryology, Shantou University Medical College, Shantou, Guangdong, China
- Department of Biomedical Science, Mercer University School of Medicine, Savannah, GA, United States of America
| | - Jinping Li
- Department of Biomedical Science, Mercer University School of Medicine, Savannah, GA, United States of America
- Department of Obstetrics and Gynecology, Memorial Health University Medical Center, Savannah, GA, United States of America
| | - Christopher Senkowski
- Department of Surgery, Curtis and Elizabeth Anderson Cancer Institute, Memorial Health University Medical Center, Savannah, GA, United States of America
| | - Zuoqing Tang
- Department of Medical Genetics, School of Basic Medical Sciences, Capital Medical University, Beijing, China
| | - Jianhao Wang
- School of Pharmaceutical Engineering and Life Science, Changzhou University, Changzhou, Jiangsu Province, China
| | - Tianhe Huang
- Department of Biomedical Science, Mercer University School of Medicine, Savannah, GA, United States of America
| | - Xue Wang
- Department of Biomedical Science, Mercer University School of Medicine, Savannah, GA, United States of America
| | - Karen Terry
- Department of Surgery, Curtis and Elizabeth Anderson Cancer Institute, Memorial Health University Medical Center, Savannah, GA, United States of America
| | - Steven Brower
- Department of Surgery & Surgical Oncology, Beth Israel Medical Center, New York, NY, United States of America
| | - Wayne Glasgow
- Department of Biomedical Science, Mercer University School of Medicine, Savannah, GA, United States of America
| | - Haibin Chen
- Department of Histology and Embryology, Shantou University Medical College, Shantou, Guangdong, China
- * E-mail: (SWJ); (HC)
| | - Shi-Wen Jiang
- Department of Biomedical Science, Mercer University School of Medicine, Savannah, GA, United States of America
- Department of Obstetrics and Gynecology, the Second Affiliated Hospital of Wenzhou Medical University, Wenzhou 325027, China
- Department of Obstetrics and Gynecology, Memorial Health University Medical Center, Savannah, GA, United States of America
- * E-mail: (SWJ); (HC)
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Abstract
One lineage of human endogenous retroviruses (HERVs), HERV-K(HML2), is upregulated in many cancers, some autoimmune/inflammatory diseases, and HIV-infected cells. Despite 3 decades of research, it is not known if these viruses play a causal role in disease, and there has been recent interest in whether they can be used as immunotherapy targets. Resolution of both these questions will be helped by an ability to distinguish between the effects of different integrated copies of the virus (loci). Research so far has concentrated on the 20 or so recently integrated loci that, with one exception, are in the human reference genome sequence. However, this viral lineage has been copying in the human population within the last million years, so some loci will inevitably be present in the human population but absent from the reference sequence. We therefore performed the first detailed search for such loci by mining whole-genome sequences generated by next-generation sequencing. We found a total of 17 loci, and the frequency of their presence ranged from only 2 of the 358 individuals examined to over 95% of them. On average, each individual had six loci that are not in the human reference genome sequence. Comparing the number of loci that we found to an expectation derived from a neutral population genetic model suggests that the lineage was copying until at least ∼250,000 years ago. IMPORTANCE About 5% of the human genome sequence is composed of the remains of retroviruses that over millions of years have integrated into the chromosomes of egg and/or sperm precursor cells. There are indications that protein expression of these viruses is higher in some diseases, and we need to know (i) whether these viruses have a role in causing disease and (ii) whether they can be used as immunotherapy targets in some of them. Answering both questions requires a better understanding of how individuals differ in the viruses that they carry. We carried out the first careful search for new viruses in some of the many human genome sequences that are now available thanks to advances in sequencing technology. We also compared the number that we found to a theoretical expectation to see if it is likely that these viruses are still replicating in the human population today.
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Huang Q, Chen H, Li J, Oliver M, Ma X, Byck D, Gao Y, Jiang SW. Epigenetic and non-epigenetic regulation of syncytin-1 expression in human placenta and cancer tissues. Cell Signal 2014; 26:648-56. [PMID: 24216608 DOI: 10.1016/j.cellsig.2013.11.002] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2013] [Accepted: 11/01/2013] [Indexed: 02/05/2023]
Abstract
Syncytin-1 is a human endogenous retroviral envelope gene (HERVW1) product specifically expressed in placental trophoblasts. By mediating the formation of syncytiotrophoblasts through cell-cell fusion, syncytin-1 plays a critical role for the placental barrier, endocrine and exchange functions. During pregnancy, syncytin-1 expression is dynamically regulated by various pathophysiological factors and pathways. This review summarizes and examines published data on epigenetic and non-epigenetic regulation of syncytin-1 gene expression, with a focus on the changes of syncytin-1 DNA methylation and expression in placental trophoblasts under preeclamptic and hypoxic conditions. The functions of syncytiotrophoblasts, the fusogenic and non-fusogenic activities of syncytin-1, and aberrant activation of syncytin-1 expression in cancer cells are also discussed. New findings on the epigenetic regulation of syncytin-1 in placentas from monozygotic/dichorionic discordant twins are analyzed. The close correlation among changes of DNMTs expression, syncytin-1 gene methylation, and syncytin-1 mRNA levels, in placentas associated with discordant fetal growth indicated a dynamic nature of syncytin-1 regulation.
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Affiliation(s)
- Qiang Huang
- The Second Affiliated Hospital of Xi'an Jiaotong University School of Medicine, Xi'an, Shaanxi 710004, China; Department of Biological Science, Mercer University School of Medicine, Savannah, GA 31404, USA
| | - Haibin Chen
- Department of Department of Histology and Embryology, Shantou University Medical College, Guandong, China
| | - Jinping Li
- Department of Biological Science, Mercer University School of Medicine, Savannah, GA 31404, USA; Department of Obstetrics and Gynecology, Mayo Medical College, Mayo Clinic and Mayo Foundation, 55902, USA
| | - Matthew Oliver
- Department of Obstetrics and Gynecology, Memorial Health University Medical Center, Savannah, GA 31404, USA
| | - Xiaoling Ma
- Department of Biological Science, Mercer University School of Medicine, Savannah, GA 31404, USA
| | - David Byck
- Department of Obstetrics and Gynecology, Memorial Health University Medical Center, Savannah, GA 31404, USA
| | - Ya Gao
- The Second Affiliated Hospital of Xi'an Jiaotong University School of Medicine, Xi'an, Shaanxi 710004, China.
| | - Shi-Wen Jiang
- Department of Biological Science, Mercer University School of Medicine, Savannah, GA 31404, USA; Department of Obstetrics and Gynecology, Mayo Medical College, Mayo Clinic and Mayo Foundation, 55902, USA; Department of Obstetrics and Gynecology, Memorial Health University Medical Center, Savannah, GA 31404, USA.
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Blagosklonny MV. Immunosuppressants in cancer prevention and therapy. Oncoimmunology 2013; 2:e26961. [PMID: 24575379 PMCID: PMC3926869 DOI: 10.4161/onci.26961] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2013] [Revised: 10/25/2013] [Accepted: 10/25/2013] [Indexed: 12/13/2022] Open
Abstract
Rapalogs such as rapamycin (sirolimus), everolimus, temserolimus, and deforolimus are indicated for the treatment of some malignancies. Rapamycin is the most effective cancer-preventive agent currently known, at least in mice, dramatically delaying carcinogenesis in both normal and cancer-prone murine strains. In addition, rapamycin and everolimus decrease the risk of cancer in patients receiving these drugs in the context of immunosuppressive regimens. In general, the main concern about the use of immunosuppressants in humans is an increased risk of cancer. Given that rapalogs are useful in cancer prevention and therapy, should they be viewed as immunosuppressants or immunostimulators? Or should we reconsider the role of immunity in cancer altogether? In addition to its anti-viral, anti-inflammatory, anti-angiogenic and anti-proliferative effects, rapamycin operates as a gerosuppressant, meaning that it inhibits the cellular conversion to a senescent state (the so-called geroconversion), a fundamental process involved in aging and age-related pathologies including cancer.
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Nissen KK, Laska MJ, Hansen B, Terkelsen T, Villesen P, Bahrami S, Petersen T, Pedersen FS, Nexø BA. Endogenous retroviruses and multiple sclerosis-new pieces to the puzzle. BMC Neurol 2013; 13:111. [PMID: 23984932 PMCID: PMC3765820 DOI: 10.1186/1471-2377-13-111] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2013] [Accepted: 08/20/2013] [Indexed: 12/04/2022] Open
Abstract
The possibility that retroviruses play a role in multiple sclerosis (MS) has long been considered; accumulating findings suggest this to be most likely in the form of human endogenous retroviruses (HERVs). A genetic test series of fifty endogenous retroviral loci for association with MS in Danes showed SNP markers near a specific endogenous retroviral locus, HERV-Fc1 located on the X-chromosome, to be positive. Bout Onset MS was associated with the HERV-Fc1 locus, while a rarer form, Primary Progressive MS, was not. Moreover, HERV-Fc1 Gag RNA in plasma was increased 4-fold in patients with recent history of attacks, relative to patients in a stable state and to healthy controls. Finally, genetic variations in restriction genes for retroviruses influence the risk of MS, providing further support for a role of retroviral elements in disease. We speculate that endogenous retroviruses may activate the innate immune system in a variety of ways, involving the host proteins, TRIMs, TLRs, TREXs and STING. Observations in HIV-positive patients suggest that antiretroviral drugs can curb MS. Thus, these new findings regarding the etiology and pathogenesis of MS, suggest alternative ways to challenge autoimmune diseases.
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Affiliation(s)
- Kari K Nissen
- Department of Biomedicine, Aarhus University, Wilhelm Meyers Allé 4, DK-8000, Aarhus, C, Denmark.
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Laska MJ, Nissen KK, Nexø BA. (Some) cellular mechanisms influencing the transcription of human endogenous retrovirus, HERV-Fc1. PLoS One 2013; 8:e53895. [PMID: 23382858 PMCID: PMC3557288 DOI: 10.1371/journal.pone.0053895] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2012] [Accepted: 12/06/2012] [Indexed: 11/18/2022] Open
Abstract
DNA methylation and histone acetylation are epigenetic modifications that act as regulators of gene expression. DNA methylation is considered an important mechanism for silencing of retroelements in the mammalian genome. However, the methylation of human endogenous retroviruses (HERVs) is not well investigated. The aim of this study was to investigate the transcriptional potential of HERV-Fc1 proviral 5'LTR in more detail, and examined the specific influence of CpG methylation on this LTR in number of cell lines. Specifically, the role of demethylating chemicals e.g. 5-aza-2' deoxycytidine and Trichostatin-A, in inducing or reactivating expression of HERV-Fc1 specific sequences and the mechanisms were investigated. In our present study, 5-aza-dC is shown to be a powerful inducer of HERV-Fc1, and at the same time it strongly inhibits methylation of DNA. Treatment with this demethylating agent 5-aza-dC, results in significantly increased levels of HERV-Fc1 expression in cells previously not expressing HERV-Fc1, or with a very low expression level. The extent of expression of HERV-Fc1 RNAs precisely correlates with the apparent extent of demethylation of the related DNA sequences. In conclusion, the results suggest that inhibition of DNA methylation/histone deacetylase can interfere with gene silencing mechanisms affecting HERV-Fc1 expression in human cells.
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