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Zhang J, Xu Y, Wang C, Tuo X, Zhao X, Qiao W, Tan J. PREB inhibits the replication of prototype foamy virus by affecting its transcription. Virol J 2023; 20:244. [PMID: 37885034 PMCID: PMC10604407 DOI: 10.1186/s12985-023-02211-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2023] [Accepted: 10/13/2023] [Indexed: 10/28/2023] Open
Abstract
BACKGROUND Foamy viruses (FVs) are unique nonpathogenic retroviruses, which remain latent in the host for a long time. Therefore, they may be safe, effective gene transfer vectors. In this study, were assessed FV-host cell interactions and the molecular mechanisms underlying FV latent infection. METHODS We used the prototype FV (PFV) to infect HT1080 cells and a PFV indicator cell line (PFVL) to measure virus titers. After 48 h of infection, the culture supernatant (i.e., cell-free PFV particles) and transfected cells (i.e., cell-associated PFV particles) were harvested and incubated with PFVL. After another 48 h, the luciferase activity was used to measure virus titers. RESULTS Through transcriptomics sequencing, we found that PREB mRNA expression was significantly upregulated. Moreover, PREB overexpression reduced PFV replication, whereas endogenous PREB knockdown increased PFV replication. PREB interacted with the Tas DNA-binding and transcriptional activation domains and interfered with its binding to the PFV long terminal repeat and internal promoter, preventing the recruitment of transcription factors and thereby inhibiting the transactivation function of Tas. PREB C-terminal 329-418 aa played a major role in inhibiting PFV replication; PREB also inhibited bovine FV replication. Therefore, PREB has a broad-spectrum inhibitory effect on FV replication. CONCLUSIONS Our results demonstrated that PREB inhibits PFV replication by impeding its transcription.
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Affiliation(s)
- Junshi Zhang
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin, 300071, China
- Department of Hematology, Oncology Centrer, Tianjin Union Medical Center, No.190 Jieyuan Road, Hongqiao District, Tianjin, 300121, P. R. China
| | - Yali Xu
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin, 300071, China
| | - Chenchen Wang
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin, 300071, China
| | - Xiaopeng Tuo
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin, 300071, China
| | - Xingli Zhao
- Department of Hematology, Oncology Centrer, Tianjin Union Medical Center, No.190 Jieyuan Road, Hongqiao District, Tianjin, 300121, P. R. China
| | - Wentao Qiao
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin, 300071, China
| | - Juan Tan
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin, 300071, China.
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Abstract
Early growth response 1 (EGR1) is a multifunctional mammalian transcription factor capable of both enhancing and/or inhibiting gene expression. EGR1 can be activated by a wide array of stimuli such as exposure to growth factors, cytokines, apoptosis, and various cellular stress states including viral infections by both DNA and RNA viruses. Following induction, EGR1 functions as a convergence point for numerous specialized signaling cascades and couples short-term extracellular signals to influence transcriptional regulation of genes required to initiate the appropriate biological response. The role of EGR1 has been extensively studied in both physiological and pathological conditions of the adult nervous system where it is readily expressed in various regions of the brain and is critical for neuronal plasticity and the formation of memories. In addition to its involvement in neuropsychiatric disorders, EGR1 has also been widely examined in the field of cancer where it plays paradoxical roles as a tumor suppressor gene or oncogene. EGR1 is also associated with multiple viral infections such as Venezuelan equine encephalitis virus (VEEV), Kaposi's sarcoma-associated herpesvirus (KSHV), herpes simplex virus 1 (HSV-1), human polyomavirus JC virus (JCV), human immunodeficiency virus (HIV), and Epstein-Barr virus (EBV). In this review, we examine EGR1 and its role(s) during viral infections. First, we provide an overview of EGR1 in terms of its structure, other family members, and a brief overview of its roles in non-viral disease states. We also review upstream regulators of EGR1 and downstream factors impacted by EGR1. Then, we extensively examine EGR1 and its roles, both direct and indirect, in regulating replication of DNA and RNA viruses.
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Affiliation(s)
- Caitlin M. Woodson
- Department of Biomedical Science and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA, United States
- Center for Emerging, Zoonotic, and Arthropod-borne Pathogens, Virginia Polytechnic Institute and State University, Blacksburg, VA, United States
| | - Kylene Kehn-Hall
- Department of Biomedical Science and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA, United States
- Center for Emerging, Zoonotic, and Arthropod-borne Pathogens, Virginia Polytechnic Institute and State University, Blacksburg, VA, United States
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3
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Yuan L, Fung TS, He J, Chen RA, Liu DX. Modulation of Viral Replication, Apoptosis and Antiviral Response by Induction and Mutual Regulation of EGR and AP-1 Family Genes During Coronavirus Infection. Emerg Microbes Infect 2022; 11:1717-1729. [PMID: 35727266 PMCID: PMC9262369 DOI: 10.1080/22221751.2022.2093133] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Coronaviruses have evolved a variety of strategies to exploit normal cellular processes and signalling pathways for their efficient reproduction in a generally hostile cellular environment. One immediate-early response gene (IEG) family, the AP-1 gene family, was previously shown to be activated by coronavirus infection. In this study, we report that another IEG family, the EGR family, is also activated in cells infected with four different coronaviruses in three genera, i.e. gammacoronavirus infectious bronchitis virus (IBV), alphacoronaviruses porcine epidemic diarrhoea virus (PEDV) and human coronavirus-229E (HCoV-229E), and betacoronavirus HCoV-OC43. Knockdown of EGR1 reduced the expression of cJUN and cFOS, and knockdown of cJUN and/or cFOS reduced the expression of EGR1, demonstrating that these two IEG families may be cross-activated and mutual regulated. Furthermore, ERK1/2 was identified as an upstream kinase, and JNK and p38 as inhibitors of EGR1 activation in coronavirus-infected cells. However, upregulation of EGR family genes, in particular EGR1, appears to play a differential role in regulating viral replication, apoptosis and antiviral response. EGR1 was shown to play a limited role in regulation of coronavirus replication, and an anti-apoptotic role in cells infected with IBV or PEDV, but not in cells infected with HCoV-229E. Upregulation of EGR1 may also play a differential role in the regulation of antiviral response against different coronaviruses. This study reveals a novel regulatory network shared by different coronaviruses in the immediate-early response of host cells to infection.
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Affiliation(s)
- Lixia Yuan
- Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou 510642, Guangdong, People's Republic of China.,Zhaoqing Branch Center of Guangdong Laboratory for Lingnan Modern Agricultural Science and Technology, Zhaoqing 526000, Guangdong, China
| | - To Sing Fung
- Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou 510642, Guangdong, People's Republic of China
| | - Jiawen He
- Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou 510642, Guangdong, People's Republic of China.,Zhaoqing Branch Center of Guangdong Laboratory for Lingnan Modern Agricultural Science and Technology, Zhaoqing 526000, Guangdong, China
| | - Rui Ai Chen
- Zhaoqing Branch Center of Guangdong Laboratory for Lingnan Modern Agricultural Science and Technology, Zhaoqing 526000, Guangdong, China
| | - Ding Xiang Liu
- Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou 510642, Guangdong, People's Republic of China.,Zhaoqing Branch Center of Guangdong Laboratory for Lingnan Modern Agricultural Science and Technology, Zhaoqing 526000, Guangdong, China
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Zhang J, Han C, Xiong Z, Qiu M, Tuo X, Wang C, Qiao W, Tan J. SGK1, a Serine/Threonine Kinase, Inhibits Prototype Foamy Virus Replication. Microbiol Spectr 2022;:e0199521. [PMID: 35438526 DOI: 10.1128/spectrum.01995-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Foamy viruses (FVs) are complex retroviruses belonging to the Spumaretrovirinae subfamily of the Retroviridae family. In contrast to human immunodeficiency virus (HIV), another member of the Retroviridae family, FVs are nonpathogenic in their natural hosts or in experimentally infected animals. Prototype foamy virus (PFV) is the only foamy virus that can infect humans through cross-species transmission and does not show any pathogenicity after infection. Consequently, PFV is considered a safe and efficient gene transfer vector. Understanding the host proteins involved in the replication of PFV and the mechanism of interaction between the host and the virus might lead to studies to improve the efficiency of gene transfer. To date, only a few host factors have been identified that affect PFV replication. In the present study, we report that PFV infection enhances the promoter activity of SGK1 (encoding serum/glucocorticoid regulated kinase 1) via the Tas protein signaling pathway, and then upregulates the mRNA and protein levels of SGK1. Overexpression of SGK1 reduced PFV replication, whereas its depletion using small interfering RNA increased PFV replication. SGK1 inhibits PFV replication by impairing the function of the PFV Tas activation domain in a kinase-independent manner and reducing the stability of the Gag protein in a kinase-dependent manner. In addition, both human and bovine SGK1 proteins inhibit the replication of bovine foamy virus (BFV) and PFV. These findings not only improved our understanding of the function of SGK1 and its relationship with foamy viruses, but also contributed to determining the antiviral mechanism of the host. IMPORTANCE Foamy viruses can integrate into the host chromosome and are nonpathogenic in natural hosts or in experimentally infected animals. Therefore, foamy viruses are considered to be safe and efficient gene transfer vectors. Persistent infection of foamy viruses is partly caused by the restrictive effect of host factors on the virus. However, only a few cellular proteins are known to influence the replication of foamy viruses. In this study, we report that SGK1 inhibits the replication of prototype foamy virus by affecting the function of the transcription activator, Tas, and reducing the stability of the structural protein, Gag. These results will increase our understanding of the interaction between the virus and host factors, deepening our perception of host antiviral defenses and the function of SGK1, and could improve the gene transfer efficiency of foamy viruses.
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Jie W, Rui-Fen Z, Zhong-Xiang H, Yan W, Wei-Na L, Yong-Ping M, Jing S, Jing-Yi C, Wan-Hong L, Xiao-Hua H, Zhi L, Yan S. Inhibition of cell proliferation by Tas of foamy viruses through cell cycle arrest or apoptosis underlines the different mechanisms of virus-host interactions. Virulence 2022; 13:342-354. [PMID: 35132916 PMCID: PMC8837258 DOI: 10.1080/21505594.2022.2029329] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Foamy viruses belong to the Spumaretrovirinae subfamily member of the Retroviridae family and produce nonpathogenic infection to hosts in the natural conditions. However, infections of foamy viruses can dramatically cause severe cytopathic effects in vitro. To date, the exact molecular mechanism has remained unclear which implied the tremendous importance of virus-host cell immune reactions. In this study, we found that the transactivator Tas in two foamy viruses isolated from Old World Monkey (OWM) induced obvious inhibition of cell proliferation via the upregulation of Foxo3a expression. It was mediated by the generation of ROS and the initiation of ER stress, and ultimately, the mitochondrial apoptosis pathway was triggered. Notably, PFV Tas contributed to the accumulation of G0/G1 phase cycle arrest induced by the activation of the p53 signaling pathway and the nuclear transportation of HDAC4 via upregulating PPM1E expression. Together, these results demonstrated the different survival strategies by which foamy virus can hijack host cell cytokines and regulate virus-host cell interactions.
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Affiliation(s)
- Wei Jie
- College of Life Sciences, Shaanxi Normal University, Xi'an, P. R. China
| | - Zhang Rui-Fen
- College of Life Sciences, Shaanxi Normal University, Xi'an, P. R. China
| | - Hu Zhong-Xiang
- College of Life Sciences, Shaanxi Normal University, Xi'an, P. R. China
| | - Wu Yan
- College of Life Sciences, Shaanxi Normal University, Xi'an, P. R. China
| | - Liu Wei-Na
- College of Life Sciences, Shaanxi Normal University, Xi'an, P. R. China
| | - Ma Yong-Ping
- College of Life Sciences, Shaanxi Normal University, Xi'an, P. R. China
| | - Song Jing
- College of Life Sciences, Shaanxi Normal University, Xi'an, P. R. China
| | - Chen Jing-Yi
- College of Life Sciences, Shaanxi Normal University, Xi'an, P. R. China
| | - Liu Wan-Hong
- School of Medicine, Wuhan University, Wuhan, P. R. China
| | - He Xiao-Hua
- School of Medicine, Wuhan University, Wuhan, P. R. China
| | - Li Zhi
- College of Life Sciences, Shaanxi Normal University, Xi'an, P. R. China
| | - Sun Yan
- College of Life Sciences, Shaanxi Normal University, Xi'an, P. R. China
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6
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Wei J, Sun Y, Wang TT, Zhu G, Liu WH, He XH, Li Z. The Regulation of Prototype Foamy Virus 5'Long Terminal Repeats and Internal Promoter by Endogenous Transcription Factors. Intervirology 2021; 65:17-28. [PMID: 34438397 DOI: 10.1159/000517539] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Accepted: 06/01/2021] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND For foamy virus, the transactivator of spumaretrovirus (Tas) could bind directly to target DNA sequences termed as Tas responsive elements and trigger the viral internal promoter (IP) and long terminal repeat (LTR) promoters. The cellular endogenous factors also play an important role in viral gene expressions. We hypothesized that except the viral transcription factor Tas, the cellular endogenous factors also affect the viral gene expression. METHODS The full length of the prototype foamy virus (PFV) genome (U21247) was used to predict the potential binding sites of the transcription factors by online software JASPAR (http://jaspar.genereg.net) and Softberry (http://linux1.softberry.com/berry.phtml?topic=index&group=programs&subgroup=promoter). The Dual-Luciferase® Reporter Assay System (Promega, USA) was used to confirm the relative luciferase activities of the test groups. The different representative activating agents or inhibitors of each canonical signal pathway were used to identify the impact of these pathways on PFV 5'LTR and IP promoters. RESULTS The results showed different cellular endogenous factors might have respective effects on PFV 5'LTR and IP. It is worth mentioning that activator protein-1 and BCL2-associated athanogene 3, 2 kinds of vital proteins associated with NF-κB and PKC pathways, could activate the basal activity of 5'LTR and IP promoters but inhibit the Tas-regulated activity of both promoters. Furthermore, PFV Tas was identified to trigger the transcription of the NF-κB promoter. CONCLUSION NF-κB had a negative effect on PFV 5'LTR and IP promoter activities, the PKC pathway might upregulate 5'LTR and IP promoter activities, and the JNK and NF-AT signal pathway could increase the Tas-regulated promoter activity of PFV 5'LTR. This study sheds light on the interaction between PFV and the host cell and may help utilize the viral promoters in retroviral vectors designed for gene transfer experiments.
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Affiliation(s)
- Jie Wei
- College of Life Sciences, Shaanxi Normal University, Xi'an, China,
| | - Yan Sun
- College of Life Sciences, Shaanxi Normal University, Xi'an, China
| | - Ting-Ting Wang
- College of Life Sciences, Shaanxi Normal University, Xi'an, China
| | - Gui Zhu
- College of Life Sciences, Shaanxi Normal University, Xi'an, China
| | - Wan-Hong Liu
- School of Medicine, Wuhan University, Wuhan, China
| | - Xiao-Hua He
- School of Medicine, Wuhan University, Wuhan, China
| | - Zhi Li
- College of Life Sciences, Shaanxi Normal University, Xi'an, China
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7
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Gessain A, Montange T, Betsem E, Bilounga Ndongo C, Njouom R, Buseyne F. Case-Control Study of the Immune Status of Humans Infected With Zoonotic Gorilla Simian Foamy Viruses. J Infect Dis 2021; 221:1724-1733. [PMID: 31822908 DOI: 10.1093/infdis/jiz660] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Accepted: 12/10/2019] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND Zoonotic simian foamy viruses (SFVs) establish persistent infections in humans, for whom the long-term consequences for health are poorly described. In this study, we aimed to characterize blood-cell phenotypes and plasma biomarkers associated with gorilla SFV infection in humans. METHODS We used a case-control design to compare 15 Cameroonian hunters infected with gorilla SFV (cases) to 15 controls matched for age and ethnicity. A flow cytometry-based phenotypic study and quantification of plasma immune biomarkers were carried out on blood samples from all participants. Wilcoxon signed-rank tests were used to compare cases and controls. RESULTS Cases had a significantly higher percentage of CD8 T lymphocytes than controls (median, 17.6% vs 13.7%; P = .03) but similar levels of B, natural killer, and CD4 T lymphocytes. Cases also had a lower proportion of recent CD4 thymic emigrants (10.9% vs 18.6%, P = .05), a higher proportion of programmed death receptor 1 (PD-1) expressing memory CD4 T lymphocytes (31.7% vs 24.7%, P = .01), and higher plasma levels of the soluble CD163 scavenger receptor (0.84 vs .59 µg/mL, P = .003) than controls. CONCLUSIONS We show, for the first time, that chronic infection with SFV is associated with T lymphocyte differentiation and monocyte activation.
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Affiliation(s)
- Antoine Gessain
- Unité d'Épidémiologie et Physiopathologie des Virus Oncogènes, Institut Pasteur, Paris, France.,Unité Mixte de Recherche du Centre National de la Recherche Scientifique 3569, Paris, France
| | - Thomas Montange
- Unité d'Épidémiologie et Physiopathologie des Virus Oncogènes, Institut Pasteur, Paris, France.,Unité Mixte de Recherche du Centre National de la Recherche Scientifique 3569, Paris, France
| | | | | | | | - Florence Buseyne
- Unité d'Épidémiologie et Physiopathologie des Virus Oncogènes, Institut Pasteur, Paris, France.,Unité Mixte de Recherche du Centre National de la Recherche Scientifique 3569, Paris, France
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Sarkar R, Verma SC. Egr-1 regulates RTA transcription through a cooperative involvement of transcriptional regulators. Oncotarget 2017; 8:91425-91444. [PMID: 29207655 PMCID: PMC5710935 DOI: 10.18632/oncotarget.20648] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Accepted: 07/26/2017] [Indexed: 11/25/2022] Open
Abstract
Kaposi's sarcoma associated herpesvirus (KSHV) regulates the host cellular environment to establish life-long persistent infection by manipulating cellular signaling pathways, with approximately 1- 5% of cells undergoing lytic reactivation during the course of infection. Egr-1 (Early Growth Response Factor-1) is one such cellular transcription factor, which gets phosphorylated during the lytic phase of viral life cycle to perpetrate its function. This study demonstrates the mechanism of how Egr-1 mediates transcription of the immediate early gene, RTA (Replication and transcription activator), which is the lytic switch gene of KSHV. Egr-1 depleted KSHV infected cells exhibited reduced expression of RTA. Also, an increase in Egr-1 phosphorylation led to a higher virion production, which was suppressed in the presence of p38 and Raf inhibitors. Reporter assays showed that coexpression of Egr-1 and CBP (CREB-binding protein) enhances RTA promoter activity as compared to the expression of either Egr-1 or CBP alone. Binding of Egr-1 and CBP at RTA promoter was analyzed by chromatin immunoprecipitation assay (ChIP), which showed an enhanced accumulation during viral reactivation. Mutation in Egr-1 binding site of the RTA promoter eliminated Egr-1 response on promoter activation. Furthermore, de novo infection of THP-1 (monocytic) and HUVECs (endothelial) cells showed an upregulation of Egr-1 phosphorylation, whereas depletion of Egr-1 reduced the mRNA levels of RTA during primary infection. Together, these results demonstrate a cooperative role of Egr-1 and CBP in mediating RTA transcription, which significantly improves our understanding of the involvement of cellular factors controlling RTA transcription in KSHV pathogenesis.
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Affiliation(s)
- Roni Sarkar
- Department of Microbiology and Immunology, University of Nevada, Reno School of Medicine, Reno, NV, USA
| | - Subhash C Verma
- Department of Microbiology and Immunology, University of Nevada, Reno School of Medicine, Reno, NV, USA
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9
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Liu Y, Betts MJ, Lei J, Wei G, Bao Q, Kehl T, Russell RB, Löchelt M. Mutagenesis of N-terminal residues of feline foamy virus Gag reveals entirely distinct functions during capsid formation, particle assembly, Gag processing and budding. Retrovirology 2016; 13:57. [PMID: 27549192 PMCID: PMC4994201 DOI: 10.1186/s12977-016-0291-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Accepted: 08/04/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Foamy viruses (FVs) of the Spumaretrovirinae subfamily are distinct retroviruses, with many features of their molecular biology and replication strategy clearly different from those of the Orthoretroviruses, such as human immunodeficiency, murine leukemia, and human T cell lymphotropic viruses. The FV Gag N-terminal region is responsible for capsid formation and particle budding via interaction with Env. However, the critical residues or motifs in this region and their functional interaction are currently ill-defined, especially in non-primate FVs. RESULTS Mutagenesis of N-terminal Gag residues of feline FV (FFV) reveals key residues essential for either capsid assembly and/or viral budding via interaction with the FFV Env leader protein (Elp). In an in vitro Gag-Elp interaction screen, Gag mutations abolishing particle assembly also interfered with Elp binding, indicating that Gag assembly is a prerequisite for this highly specific interaction. Gradient sedimentation analyses of cytosolic proteins indicate that wild-type Gag is mostly assembled into virus capsids. Moreover, proteolytic processing of Gag correlates with capsid assembly and is mostly, if not completely, independent from particle budding. In addition, Gag processing correlates with the presence of packaging-competent FFV genomic RNA suggesting that Pol encapsidation via genomic RNA is a prerequisite for Gag processing. Though an appended heterogeneous myristoylation signal rescues Gag particle budding of mutants unable to form capsids or defective in interacting with Elp, it fails to generate infectious particles that co-package Pol, as evidenced by a lack of Gag processing. CONCLUSIONS Changes in proteolytic Gag processing, intracellular capsid assembly, particle budding and infectivity of defined N-terminal Gag mutants highlight their essential, distinct and only partially overlapping roles during viral assembly and budding. Discussion of these findings will be based on a recent model developed for Gag-Elp interactions in prototype FV.
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Affiliation(s)
- Yang Liu
- Department of Molecular Diagnostics of Oncogenic Infections, Research Program Infection and Cancer, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 242, 69120, Heidelberg, Germany.,Center for Cancer Research, National Cancer Institute, Frederick, MD, USA
| | - Matthew J Betts
- CellNetworks, Bioquant, University of Heidelberg, Im Neuenheimer Feld 267, 69120, Heidelberg, Germany
| | - Janet Lei
- Department of Molecular Diagnostics of Oncogenic Infections, Research Program Infection and Cancer, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 242, 69120, Heidelberg, Germany.,Department of Oncology, University of Oxford, Oxford, UK
| | - Guochao Wei
- Department of Molecular Diagnostics of Oncogenic Infections, Research Program Infection and Cancer, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 242, 69120, Heidelberg, Germany
| | - Qiuying Bao
- Department of Molecular Diagnostics of Oncogenic Infections, Research Program Infection and Cancer, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 242, 69120, Heidelberg, Germany.,Biology Department, East China Normal University, Shanghai, China
| | - Timo Kehl
- Department of Molecular Diagnostics of Oncogenic Infections, Research Program Infection and Cancer, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 242, 69120, Heidelberg, Germany
| | - Robert B Russell
- CellNetworks, Bioquant, University of Heidelberg, Im Neuenheimer Feld 267, 69120, Heidelberg, Germany.,Biochemie Zentrum Heidelberg (BZH), Im Neuenheimer Feld 328, 69120, Heidelberg, Germany
| | - Martin Löchelt
- Department of Molecular Diagnostics of Oncogenic Infections, Research Program Infection and Cancer, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 242, 69120, Heidelberg, Germany.
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10
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Lambert C, Rua R, Gessain A, Buseyne F. A new sensitive indicator cell line reveals cross-transactivation of the viral LTR by gorilla and chimpanzee simian foamy viruses. Virology 2016; 496:219-226. [PMID: 27348053 DOI: 10.1016/j.virol.2016.06.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Revised: 06/13/2016] [Accepted: 06/14/2016] [Indexed: 12/25/2022]
Abstract
The majority of currently identified simian foamy virus (SFV)-infected Cameroonian and Gabonese individuals harbor SFV from the gorilla lineage. We constructed an indicator cell line for the quantification of gorilla SFVs, in which the U3 sequence of a gorilla SFV directs the expression of the β-galactosidase protein. The gorilla foamy virus activated β-galactosidase (GFAB) cells efficiently quantified two zoonotic primary gorilla isolates and SFVs from three chimpanzee subspecies. Primary gorilla SFVs replicated more slowly and at lower levels than primary chimpanzee SFVs. Analysis of previously described motifs of Tas proteins and U3 LTRs involved in viral gene synthesis revealed conservation of such motifs in Tas proteins from gorilla and chimpanzee SFVs, but little sequence homology in the LTR regions previously shown to interact with viral and cellular factors.
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Affiliation(s)
- Caroline Lambert
- Unité d'épidémiologie et physiopathologie des virus oncogènes, Institut Pasteur, 28 rue du Dr Roux, 75015 Paris, France; UMR CNRS 3569, Institut Pasteur, Paris 75015, France; Sorbonne Paris Cité, Cellule Pasteur, Université Paris Diderot, Institut Pasteur, 75015 Paris, France
| | - Réjane Rua
- Unité d'épidémiologie et physiopathologie des virus oncogènes, Institut Pasteur, 28 rue du Dr Roux, 75015 Paris, France
| | - Antoine Gessain
- Unité d'épidémiologie et physiopathologie des virus oncogènes, Institut Pasteur, 28 rue du Dr Roux, 75015 Paris, France; UMR CNRS 3569, Institut Pasteur, Paris 75015, France
| | - Florence Buseyne
- Unité d'épidémiologie et physiopathologie des virus oncogènes, Institut Pasteur, 28 rue du Dr Roux, 75015 Paris, France; UMR CNRS 3569, Institut Pasteur, Paris 75015, France.
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11
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Rola-Łuszczak M, Materniak M, Pluta A, Hulst M, Kuźmak J. Transcriptomic microarray analysis of BoMac cells after infection with bovine foamy virus. Arch Virol 2014; 159:1515-9. [PMID: 24380972 DOI: 10.1007/s00705-013-1959-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2013] [Accepted: 11/18/2013] [Indexed: 12/22/2022]
Abstract
Bovine foamy virus (BFV) infections are highly prevalent among cattle worldwide. However, relatively little is known about the impact of this virus on the host immune system. In our study, we focused on a bovine macrophage cell line (BoMac) and examined changes in the BoMac transcriptome after in vitro infection with BFV using bovine BLOPlus oligo microarrays. One hundred twenty-four genes showed significant changes in expression level. The biological process categories found to be enriched include metabolic processes, cell communication, transport, immune system processes, and response to extracellular stimuli. RT-qPCR was applied to confirm the results obtained for representative genes.
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Affiliation(s)
- Marzena Rola-Łuszczak
- Department of Biochemistry, National Veterinary Research Institute, Partyzantów 57, 24-100, Pulawy, Poland,
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12
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Kehl T, Tan J, Materniak M. Non-simian foamy viruses: molecular virology, tropism and prevalence and zoonotic/interspecies transmission. Viruses 2013; 5:2169-209. [PMID: 24064793 PMCID: PMC3798896 DOI: 10.3390/v5092169] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2013] [Revised: 09/04/2013] [Accepted: 09/05/2013] [Indexed: 12/27/2022] Open
Abstract
Within the field of retrovirus, our knowledge of foamy viruses (FV) is still limited. Their unique replication strategy and mechanism of viral persistency needs further research to gain understanding of the virus-host interactions, especially in the light of the recent findings suggesting their ancient origin and long co-evolution with their nonhuman hosts. Unquestionably, the most studied member is the primate/prototype foamy virus (PFV) which was originally isolated from a human (designated as human foamy virus, HFV), but later identified as chimpanzee origin; phylogenetic analysis clearly places it among other Old World primates. Additionally, the study of non-simian animal FVs can contribute to a deeper understanding of FV-host interactions and development of other animal models. The review aims at highlighting areas of special interest regarding the structure, biology, virus-host interactions and interspecies transmission potential of primate as well as non-primate foamy viruses for gaining new insights into FV biology.
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Affiliation(s)
- Timo Kehl
- German Cancer Research Center, INF242, Heidelberg 69120, Germany
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +49-6221-42-4935; Fax: +49-6221-42-4932
| | - Juan Tan
- College of Life Sciences, Nankai University, 94 Weijin Road, Tianjin 300071, China; E-Mail:
| | - Magdalena Materniak
- Department of Biochemistry, National Veterinary Research Institute, Partyzantow Ave. 57, Pulawy 24-100, Poland; E-Mail:
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13
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Abstract
Foamy viruses (FVs) are distinct members of the retrovirus (RV) family. In this chapter, the molecular regulation of foamy viral transcription, splicing, polyadenylation, and RNA export will be compared in detail to the orthoretroviruses. Foamy viral transcription is regulated in early and late phases, which are separated by the usage of two promoters. The viral transactivator protein Tas activates both promoters. The nature of this early-late switch and the molecular mechanism used by Tas are unique among RVs. RVs duplicate the long terminal repeats (LTRs) during reverse transcription. These LTRs carry both a promoter region and functional poly(A) sites. In order to express full-length transcripts, RVs have to silence the poly(A) signal in the 5' LTR and to activate it in the 3' LTR. FVs have a unique R-region within these LTRs with a major splice donor (MSD) at +51 followed by a poly(A) signal. FVs use a MSD-dependent mechanism to inactivate the polyadenylation. Most RVs express all their genes from a single primary transcript. In order to allow expression of more than one gene from this RNA, differential splicing is extensively used in complex RVs. The splicing pattern of FV is highly complex. In contrast to orthoretroviruses, FVs synthesize the Pol precursor protein from a specific and spliced transcript. The LTR and IP-derived primary transcripts are spliced into more than 15 different mRNA species. Since the RNA ratios have to be balanced, a tight regulation of splicing is required. Cellular quality control mechanisms retain and degrade unspliced or partially spliced RNAs in the nucleus. In this review, I compare the RNA export pathways used by orthoretroviruses with the distinct RNA export pathway used by FV. All these steps are highly regulated by host and viral factors and set FVs apart from all other RVs.
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Affiliation(s)
- Jochen Bodem
- Institute of Virology and Immunobiology, University of Würzburg, Würzburg, Germany
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14
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Liu Y, Kim YB, Löchelt M. N-terminally myristoylated feline foamy virus Gag allows Env-independent budding of sub-viral particles. Viruses 2011; 3:2223-37. [PMID: 22163342 DOI: 10.3390/v3112223] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2011] [Revised: 11/04/2011] [Accepted: 11/04/2011] [Indexed: 01/09/2023] Open
Abstract
Foamy viruses (FVs) are distinct retroviruses classified as Spumaretrovirinae in contrast to the other retroviruses, the Orthoretrovirinae. As a unique feature of FVs, Gag is not sufficient for sub-viral particle (SVP) release. In primate and feline FVs (PFV and FFV), particle budding completely depends on the cognate FV Env glycoproteins. It was recently shown that an artificially added N-terminal Gag myristoylation signal (myr-signal) overcomes this restriction in PFV inducing an Orthoretrovirus-like budding phenotype. Here we show that engineered, heterologous N-terminal myr-signals also induce budding of the distantly related FFV Gag. The budding efficiency depends on the myr-signal and its location relative to the N-terminus of Gag. When the first nine amino acid residues of FFV Gag were replaced by known myr-signals, the budding efficiency as determined by the detection of extracellular SVPs was low. In contrast, adding myr-signals to the intact N-terminus of FFV Gag resulted in a more efficient SVP release. Importantly, budding of myr-Gag proteins was sensitive towards inhibition of cellular N-myristoyltransferases. As expected, the addition or insertion of myr-signals that allowed Env-independent budding of FFV SVPs also retargeted Gag to plasma membrane-proximal sites and other intracellular membrane compartments. The data confirm that membrane-targeted FV Gag has the capacity of SVP formation.
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15
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Bedadala GR, Palem JR, Graham L, Hill JM, McFerrin HE, Hsia SC. Lytic HSV-1 infection induces the multifunctional transcription factor Early Growth Response-1 (EGR-1) in rabbit corneal cells. Virol J 2011; 8:262. [PMID: 21619646 PMCID: PMC3120787 DOI: 10.1186/1743-422x-8-262] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2011] [Accepted: 05/27/2011] [Indexed: 01/07/2023] Open
Abstract
BACKGROUND Herpes simplex virus type-1 (HSV-1) infections can cause a number of diseases ranging from simple cold sores to dangerous keratitis and lethal encephalitis. The interaction between virus and host cells, critical for viral replication, is being extensively investigated by many laboratories. In this study, we tested the hypothesis that HSV-1 lytic infection triggers the expression of important multi-functional transcription factor Egr1. The mechanisms of induction are mediated, at least in part, by signaling pathways such as NFκB and CREB. METHODS SIRC, VERO, and 293HEK cell lines were infected with HSV-1, and the Egr-1 transcript and protein were detected by RT-PCR and Western blot, respectively. The localization and expression profile of Egr-1 were investigated further by immunofluorescence microscopy analyses. The recruitment of transcription factors to the Egr-1 promoter during infection was studied by chromatin immunoprecipitation (ChIP). Various inhibitors and dominant-negative mutant were used to assess the mechanisms of Egr-1 induction and their effects were addressed by immunofluorescence microscopy. RESULTS Western blot analyses showed that Egr-1 was absent in uninfected cells; however, the protein was detected 24-72 hours post treatment, and the response was directly proportional to the titer of the virus used for infection. Using recombinant HSV-1 expressing EGFP, Egr-1 was detected only in the infected cells. ChIP assays demonstrated that NFкB and cAMP response element binding protein (CREB) were recruited to the Egr-1 promoter upon infection. Additional studies showed that inhibitors of NFкB and dominant-negative CREB repressed the Egr-1 induction by HSV-1 infection. CONCLUSION Collectively, these results demonstrate that Egr-1 is expressed rapidly upon HSV-1 infection and that this novel induction could be due to the NFкB/CREB-mediated transactivation. Egr-1 induction might play a key role in the viral gene expression, replication, inflammation, and the disease progression.
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Affiliation(s)
- Gautam R Bedadala
- Department of Pharmaceutical Sciences, University of Maryland Eastern Shore School of Pharmacy, Princess Anne, MD, USA
| | - Jayavardhana R Palem
- Department of Basic Pharmaceutical Sciences, University of Louisiana Monroe School of Pharmacy, Monroe, LA, USA
| | - Lorna Graham
- Department of Pharmaceutical Sciences, University of Maryland Eastern Shore School of Pharmacy, Princess Anne, MD, USA
| | - James M Hill
- Department of Ophthalmology, Louisiana State University Health Sciences Center, New Orleans, LA, USA
| | - Harris E McFerrin
- Department of Biology, Xavier University of Louisiana, New Orleans, LA, USA
| | - Shao-Chung Hsia
- Department of Pharmaceutical Sciences, University of Maryland Eastern Shore School of Pharmacy, Princess Anne, MD, USA
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16
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Liu W, Backes P, Löchelt M. Importance of the major splice donor and redefinition of cis-acting sequences of gutless feline foamy virus vectors. Virology 2009; 394:208-17. [PMID: 19775717 DOI: 10.1016/j.virol.2009.08.028] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2009] [Revised: 08/07/2009] [Accepted: 08/19/2009] [Indexed: 12/18/2022]
Abstract
Foamy virus vectors are potent alternatives to lenti- and gamma-retroviral vectors for gene therapy. To construct and optimize gutless feline foamy virus (FFV) replication-deficient (RD) vectors, viral elements essential for optimal efficient marker gene transduction were characterized and fine-mapped and packaging clones constructed. For these purposes, new Gag and Pol expression clones which allow efficient expression of packaging proteins and vectors carrying deletions in coding and non-coding regions of the genome were constructed and functionally evaluated. These studies demonstrate that the 5' major splice donor (5' SD) is indispensable for RD vectors while defined mutations introduced to inactivate the gag start codon improve transgene delivery efficiency. Based on these findings, new gutless FFV vectors were generated yielding un-concentrated vector titers above 10(5) transducing units (TU)/ml. By minimizing the second cis-acting sequence in the pol gene, only 3.8 kb viral sequences are maintained in the novel gutless FFV RD vectors.
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Affiliation(s)
- Weibin Liu
- Division of Genome Modifications and Carcinogenesis, Focus Infection and Cancer, German Cancer Research Center, (F020), Im Neuenheimer Feld 242, 69120 Heidelberg, Germany
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17
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Chen SH, Yao HW, Chen IT, Shieh B, Li C, Chen SH. Suppression of transcription factor early growth response 1 reduces herpes simplex virus lethality in mice. J Clin Invest 2008; 118:3470-7. [PMID: 18769632 DOI: 10.1172/jci35114] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2008] [Accepted: 07/16/2008] [Indexed: 02/06/2023] Open
Abstract
Herpes simplex virus type 1 (HSV-1) infection is the most common cause of sporadic, fatal encephalitis, but current understanding of how the virus interacts with cellular factors to regulate disease progression is limited. Here, we show that HSV-1 infection induced the expression of the cellular transcription factor early growth response 1 (Egr-1) in a human neuronal cell line. Egr-1 increased viral replication by activating promoters of viral productive cycle genes through binding to its corresponding sequences in the viral promoters. Mouse studies confirmed that Egr-1 expression was enhanced in HSV-1-infected brains and that Egr-1 functions to promote viral replication in embryonic fibroblasts. Furthermore, Egr-1 deficiency or knockdown of Egr-1 by a DNA-based enzyme greatly reduced the mortality of HSV-1-infected mice by decreasing viral loads in tissues. This study provides what we believe is the first evidence that Egr-1 increases the mortality of HSV-1 encephalitis by enhancing viral replication. Moreover, blocking this cellular machinery exploited by the virus could prevent host mortality.
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Affiliation(s)
- Shih-Heng Chen
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Republic of China
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18
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Romagnoli L, Sariyer IK, Tung J, Feliciano M, Sawaya BE, Del Valle L, Ferrante P, Khalili K, Safak M, White MK. Early growth response-1 protein is induced by JC virus infection and binds and regulates the JC virus promoter. Virology 2008; 375:331-41. [PMID: 18353421 DOI: 10.1016/j.virol.2008.02.021] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2007] [Revised: 08/22/2007] [Accepted: 02/14/2008] [Indexed: 11/18/2022]
Abstract
JC virus (JCV) is a human polyomavirus that can emerge from a latent state to cause the cytolytic destruction of oligodendrocytes in the brain resulting in the fatal demyelinating disease, progressive multifocal leukoencephalopathy (PML). Previous studies described a cis-acting transcriptional regulatory element in the JCV non-coding control region (NCCR) that is involved in the response of JCV to cytokines. This consists of a 23 base pair GGA/C rich sequence (GRS) near the replication origin (5112 to +4) that contains potential binding sites for Sp1 and Egr-1. Gel shift analysis showed that Egr-1, but not Sp1, bound to GRS. Evidence is presented that the GRS gel shift seen on cellular stimulation is due to Egr-1. Thus, TPA-induced GRS gel shift could be blocked by antibody to Egr-1. Further, the TPA-induced GRS DNA/protein complex was isolated and found to contain Egr-1 by Western blot. No other Egr-1 sites were found in the JCV NCCR. Functionally, Egr-1 was found to stimulate transcription of JCV late promoter but not early promoter reporter constructs. Mutation of the Egr-1 site abrogated Egr-1 binding and virus with the mutated Egr-1 site showed markedly reduced VP1 expression and DNA replication. Infection of primary astrocytes by wild-type JCV induced Egr-1 nuclear expression that was maximal at 5-10 days post-infection. Finally, upregulation of Egr-1 was detected in PML by immunohistochemistry. These data suggest that Egr-1 induction may be important in the life cycle of JCV and PML pathogenesis.
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Affiliation(s)
- Luca Romagnoli
- Center for Neurovirology, Department of Neuroscience, Temple University School of Medicine, Philadelphia, PA 19122, USA
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19
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Bastone P, Romen F, Liu W, Wirtz R, Koch U, Josephson N, Langbein S, Löchelt M. Construction and characterization of efficient, stable and safe replication-deficient foamy virus vectors. Gene Ther 2007; 14:613-20. [PMID: 17203107 DOI: 10.1038/sj.gt.3302890] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
As serious side effects affected recent virus-mediated gene transfer studies, novel vectors with improved safety profiles are urgently needed. In the present study, replication-deficient retroviral vectors based on feline foamy virus (FFV) were constructed and analyzed. The novel FFV vectors are devoid of almost the complete env gene plus the internal promoter - accessory bel gene cassette including the gene for the viral transcriptional transactivator Bel1/Tas. In these Bel1/Tas-independent vectors, expression of the lacZ (beta-galactosidase) marker gene is directed by the heterologous, constitutively active human ubiquitin C promoter (ubi). Env-transcomplemented vectors have un-concentrated titers of more than 10(5) transducing units/ml. The vectors allow efficient transduction of a broad array of diverse target cells, which can be increased by repeated vector exposure. However, the number of lacZ marker gene expressing cells decreased slightly upon serial passages of the transduced cells. Vectors carrying a self-inactivating (SIN) deletion of the TATA box and most parts of the viral promoter were not rescued by wt FFV whereas those with the intact or a partially deleted promoter were readily reactivated. This finding indicates that the viral promoters are in fact non-functional, pointing to a highly advantageous safety profile of these new FFV-ubi-lacZ-SIN vectors.
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Affiliation(s)
- P Bastone
- Abt. Genomveränderungen und Karzinogenese, Forschungsschwerpunkt Infektion und Krebs, Deutsches Krebsforschungszentrum, Heidelberg, Germany
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20
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Cai Y, Liu Y, Zhang X. Induction of transcription factor Egr-1 gene expression in astrocytoma cells by Murine coronavirus infection. Virology 2006; 355:152-63. [PMID: 16908043 PMCID: PMC1851928 DOI: 10.1016/j.virol.2006.07.012] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2006] [Revised: 05/19/2006] [Accepted: 07/10/2006] [Indexed: 11/22/2022]
Abstract
Mouse hepatitis virus (MHV) causes encephalitis and demyelination in the central nervous system (CNS) of susceptible rodents. Astrocytes are one of the major targets for MHV infection in the CNS, and respond to MHV infection by expressing diverse molecules that may contribute to CNS pathogenesis. Here we characterized the activation of an immediate-early transcription factor Egr-1 by MHV infection in an astrocytoma cell line. We found that the expression of Egr-1 was dramatically increased following virus infection. Using various inhibitors of mitogen-activated protein kinases, we identified that the extracellular signal-regulated kinases 1/2 were involved in the activation of Egr-1 transcription by MHV infection. Experiments with ultraviolet light-inactivated virus revealed that the induction of Egr-1 did not require virus replication and was likely mediated during cell entry. We further found that over-expression of Egr-1 suppressed the expression of BNip3, a pro-apoptotic member of the Bcl-2 family. This finding may provide an explanation for our previously observed down-regulation of BNip3 by MHV infection in astrocytoma cells (Cai, Liu, Yu, and Zhang, Virology 316:104-115, 2003). Furthermore, knockdown of Egr-1 by an siRNA inhibited MHV propagation, suggesting the biological relevance of Egr-1 induction to virus replication. In addition, the persistence/demylinating-positive strains (JHM and A59) induced Egr-1 expression, whereas the persistence/demylinating-negative strain (MHV-2) did not. These results indicate a correlation between the ability of MHVs to induce Egr-1 expression and their ability to cause demyelination in the CNS, which may suggest a potential role for the induction of Egr-1 in viral pathogenesis.
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Affiliation(s)
| | | | - Xuming Zhang
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, 4301 W. Markham Street, Slot 511, Little Rock, AR 72205, USA
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Bastone P, Bravo IG, Löchelt M. Feline foamy virus-mediated marker gene transfer: identification of essential genetic elements and influence of truncated and chimeric proteins. Virology 2006; 348:190-9. [PMID: 16443252 DOI: 10.1016/j.virol.2005.12.022] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2005] [Revised: 11/22/2005] [Accepted: 12/16/2005] [Indexed: 11/16/2022]
Abstract
Retroviral vectors derived from foamy or spumaretroviruses are considered promising tools for targeted gene delivery and vaccination purposes. In order to fully exploit this potential, we identified essential cis-acting sequences on the feline foamy virus (FFV) genome by constructing and analyzing a series of FFV-based replication-deficient vector genomes. Cis-acting sequences essentially required for marker gene transfer were found to be localized at two sites on the FFV genome: (i) in the 5'-untranslated region and close to the gag ATG and (ii) in the central part of the pol gene. The presence of two cis-acting sequences and their relative location on the FFV genome are similar but not identical to the functionally corresponding elements described for simian and primate foamy viruses.
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Affiliation(s)
- Patrizia Bastone
- Department Genome Modifications and Carcinogenesis, Focus Infection and Cancer, German Cancer Research Centre, Heidelberg, Germany
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22
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Sun KH, Lin HY, Chen LW, Tai HY, Lin ML, Feng CK, Sung JS, Liu HF, Liu WT. Human foamy virus bel1 sequence in patients with autoimmune rheumatic diseases. Clin Rheumatol 2005; 25:694-9. [PMID: 16365688 DOI: 10.1007/s10067-005-0146-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2005] [Accepted: 10/17/2005] [Indexed: 11/25/2022]
Abstract
Since the association between human foamy virus (HFV) with rheumatic autoimmune diseases remains controversial, this study was designed to determine the relationship between HFV and systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), or progressive systemic sclerosis (PSS). The bel1 and Pol sequences of HFV were measured by reverse transcriptase-polymerase chain reaction (RT-PCR) in plasma and by PCR in peripheral blood mononuclear cells (PBMC) from patients with SLE, RA, and PSS. Antibodies against Bel1 and Pol were assessed by enzyme-linked immunosorbent assay. Active HFV infections were detected by a Bel1-responsive indicator cell line. The bel1 sequence was detected in the plasma (SLE 59, RA 32, and PSS 63%) and PBMC (SLE 54, RA 71, and PSS 57%). However, active HFV infection existed only in patients with the bel1 sequence in both plasma and PBMC. In SLE patients, antibodies against Bel1 (7.1%) and Pol (4.5%) were also detected. The results suggest a possible association between HFV infection and these autoimmune rheumatic diseases.
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MESH Headings
- Adolescent
- Adult
- Aged
- Arthritis, Rheumatoid/blood
- Arthritis, Rheumatoid/diagnosis
- Arthritis, Rheumatoid/virology
- Autoimmune Diseases/blood
- Autoimmune Diseases/diagnosis
- Autoimmune Diseases/virology
- Child
- DNA, Viral/blood
- DNA-Binding Proteins/blood
- DNA-Binding Proteins/genetics
- Humans
- Leukocytes, Mononuclear/virology
- Lupus Erythematosus, Systemic/blood
- Lupus Erythematosus, Systemic/diagnosis
- Lupus Erythematosus, Systemic/virology
- Middle Aged
- RNA, Viral/blood
- Retroviridae Infections/blood
- Retroviridae Infections/complications
- Retroviridae Infections/diagnosis
- Retroviridae Proteins/blood
- Retroviridae Proteins/genetics
- Scleroderma, Systemic/blood
- Scleroderma, Systemic/diagnosis
- Scleroderma, Systemic/virology
- Simian foamy virus/isolation & purification
- Simian foamy virus/pathogenicity
- Trans-Activators/blood
- Trans-Activators/genetics
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Affiliation(s)
- Kuang-Hui Sun
- Institute of Biotechnology in Medicine, School of Medical Technology and Engineering, National Yang-Ming University, Taipei, Taiwan, Republic of China.
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23
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Geiselhart V, Bastone P, Kempf T, Schnölzer M, Löchelt M. Furin-mediated cleavage of the feline foamy virus Env leader protein. J Virol 2004; 78:13573-81. [PMID: 15564468 PMCID: PMC533928 DOI: 10.1128/jvi.78.24.13573-13581.2004] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2004] [Accepted: 07/19/2004] [Indexed: 11/20/2022] Open
Abstract
The molecular biology of spuma or foamy retroviruses is different from that of the other members of the Retroviridae. Among the distinguishing features, the N-terminal domain of the foamy virus Env glycoprotein, the 16-kDa Env leader protein Elp, is a component of released, infectious virions and is required for particle budding. The transmembrane protein Elp specifically interacts with N-terminal Gag sequences during morphogenesis. In this study, we investigate the mechanism of Elp release from the Env precursor protein. By a combination of genetic, biochemical, and biophysical methods, we show that the feline foamy virus (FFV) Elp is released by a cellular furin-like protease, most likely furin itself, generating an Elp protein consisting of 127 amino acid residues. The cleavage site fully conforms to the rules for an optimal furin site. Proteolytic processing at the furin cleavage site is required for full infectivity of FFV. However, utilization of other furin proteases and/or cleavage at a suboptimal signal peptidase cleavage site can partially rescue virus viability. In addition, we show that FFV Elp carries an N-linked oligosaccharide that is not conserved among the known foamy viruses.
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Affiliation(s)
- Verena Geiselhart
- Abt. Genomveränderung und Carcinogenese, Forschungsschwerpunkt Infektion und Krebs, Deutsches Krebsforschungszentrum, Im Neuenheimer Feld 242, 69120 Heidelberg, Germany
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24
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Bannert H, Muranyi W, Ogryzko VV, Nakatani Y, Flügel RM. Coactivators p300 and PCAF physically and functionally interact with the foamy viral trans-activator. BMC Mol Biol 2004; 5:16. [PMID: 15350211 PMCID: PMC517496 DOI: 10.1186/1471-2199-5-16] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2004] [Accepted: 09/06/2004] [Indexed: 11/22/2022] Open
Abstract
Background Foamy virus Bel1/Tas trans-activators act as key regulators of gene expression and directly bind to Bel1 response elements (BRE) in both the internal and the 5'LTR promoters leading to strong transcriptional trans-activation. Cellular coactivators interacting with Bel1/Tas are unknown to date. Results Transient expression assays, co-immunoprecipitation experiments, pull-down assays, and Western blot analysis were used to demonstrate that the coactivator p300 and histone acetyltransferase PCAF specifically interact with the retroviral trans-activator Bel1/Tas in vivo. Here we show that the Bel1/Tas-mediated trans-activation was enhanced by the coactivator p300, histone acetyltransferases PCAF and SRC-1 based on the crucial internal promoter BRE. The Bel1/Tas-interacting region was mapped to the C/H1 domain of p300 by co-immunoprecipitation and pull-down assays. In contrast, coactivator SRC-1 previously reported to bind to the C-terminal domain of p300 did not directly interact with the Bel1 protein but nevertheless enhanced Bel1/Tas-mediated trans-activation. Cotransfection of Bel1/Tas and p300C with an expression plasmid containing the C/H1domain partially inhibited the p300C-driven trans-activation. Conclusions Our data identify p300 and PCAF as functional partner molecules that directly interact with Bel1/Tas. Since the acetylation activities of the three coactivators reside in or bind to the C-terminal regions of p300, a C/H1 expression plasmid was used as inhibitor. This is the first report of a C/H1 domain-interacting retroviral trans-activator capable of partially blocking the strong Bel1/Tas-mediated activation of the C-terminal region of coactivator p300. The potential mechanisms and functional roles of the three histone and factor acetyltransferases p300, PCAF, and SRC-1 in Bel1/Tas-mediated trans-activation are discussed.
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Affiliation(s)
- Helmut Bannert
- Department of Retroviral Gene Expression, German Cancer Research Center, Applied Tumor Virology, Heidelberg, Germany
| | - Walter Muranyi
- Abteilung Virologie, Hygiene-Institut, Universität Heidelberg, 69120 Heidelberg, Germany
| | - Vasily V Ogryzko
- André Lwoff Institut, CNRS UR079, 7 Rue Guy Moquet, Villejuif 94801, France
| | - Yoshihiro Nakatani
- Dana-Farber Cancer Institute, 44 Binney Street, Harvard Medical School, Boston, MA 02115, USA
| | - Rolf M Flügel
- Department of Retroviral Gene Expression, German Cancer Research Center, Applied Tumor Virology, Heidelberg, Germany
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25
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Abstract
An overview of the pattern and mechanisms of spuma or foamy virus (FV) gene expression is presented. FVs are complex retroviruses with respect to their genetic outfit and the elements used to control and regulate expression of the viral genome. The increased insight into transcriptional and posttranscriptional mechanisms has revealed that the FVs are distinct, unconventional retroviruses clearly apart from the orthoretroviruses. Although less characterized than the orthoretroviruses, FVs have several unique features that are important for construction and assembly of FV-based vectors for targeted gene delivery and vaccination purposes. Some of these distinguishing features are directly related to the FV-specific mechanisms of gene expression and include (1) the presence of an internal, functional active second transcription unit for expression of the nonstructural genes, (2) the utilization of a subgenomic, spliced transcript for Pol protein expression, and (3) distinct but not yet understood mechanisms for the nuclear exit of defined transcripts and thus an additional level of posttranscriptional control of gene expression. Finally, the interactions of the viral transactivator not only with both viral promoters but also with regulatory elements controlling the expression of defined cellular genes are an important issue with respect to vector development and the apparent apathogenicity of FVs in their natural hosts.
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Affiliation(s)
- M Löchelt
- Abteilung Retrovirale Genexpression, Angewandte Tumorvirologie, Deutsches Krebsforschungszentrum, Im Neuenheimer Feld 242, 69009 Heidelberg, Germany.
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26
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Schwantes A, Truyen U, Weikel J, Weiss C, Löchelt M. Application of chimeric feline foamy virus-based retroviral vectors for the induction of antiviral immunity in cats. J Virol 2003; 77:7830-42. [PMID: 12829823 PMCID: PMC161927 DOI: 10.1128/jvi.77.14.7830-7842.2003] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In order to define the potential and applicability of replication-competent foamy virus-based vaccine vectors, recombinant feline foamy virus (FFV) vectors encoding defined segments of the feline calicivirus (FCV) capsid protein E domain were constructed. In cell cultures, these FFV-FCV vectors efficiently transduced and expressed a hybrid fusion protein consisting of the essential FFV Bet protein and the attached FCV E domains. The stability of the vectors in vitro was inversely correlated to the size of the heterologous insert. The deletion of a part of the FFV U3 sequence in these FFV-FCV vectors did not interfere with replication and titer in cell cultures but increased the genetic stability of the hybrid vectors. Selected chimeric vectors were injected into immunocompetent cats and persisted in the transduced host concomitant with a strong and specific humoral immune response against vector components. In a substantial number of cats, antibodies directed against the FCV E domain were induced by the FFV-FCV vectors, but no FCV-neutralizing activities were detectable in vitro. When the vaccinated cats were challenged with a high-titer FCV dose, sterile immunity was not induced by any of the hybrid FFV-FCV vectors. However, the FFV-FCV vector with a truncated U3 region of the long terminal repeat promoter significantly reduced the duration of FCV shedding after challenge and suppressed the appearance of FCV-specific ulcers. Possible mechanisms contributing to the partial protection will be discussed.
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Affiliation(s)
- Astrid Schwantes
- Abteilung Retrovirale Genexpression, Forschungsschwerpunkt Angewandte Tumorvirologie, Deutsches Krebsforschungszentrum, Im Neuenheimer Feld 242, 69009 Heidelberg, Germany
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27
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Geiselhart V, Schwantes A, Bastone P, Frech M, Löchelt M. Features of the Env leader protein and the N-terminal Gag domain of feline foamy virus important for virus morphogenesis. Virology 2003; 310:235-44. [PMID: 12781711 DOI: 10.1016/s0042-6822(03)00125-9] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Previous studies have shown that foamy virus (FV) particle budding, especially the involvement of the viral env glycoprotein is different from that of other (ortho) retroviruses: the N-terminal Env leader protein Elp is a constituent of released FV particles. A defined sequence in Elp required for particle budding binds to the MA domain of Gag. To extend these findings, we show that feline FV Elp is a membrane-anchored protein with the N-terminus located inside the particle. Thus, the internal/cytoplasmic domain of Elp has the correct topology for interacting with Gag during budding. In addition to Elp, an Elp-related protein of about 9 kDa was shown to be virion associated and is probably generated by cellular signal peptidases. Besides the function of Elp binding, the N-terminal domain of Gag was shown to be required for proper localization of feline FV Gag to the cytoplasm and the perinuclear/nuclear region.
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Affiliation(s)
- Verena Geiselhart
- Abteilung Retrovirale Genexpression, Forschungsschwerpunkt Angewandte Tumorvirologie, Deutsches Krebsforschungszentrum, Heidelberg, Germany
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28
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Abstract
DNA arrays can be used to simultaneously analyze the expression of hundreds of genes and permit systematic approaches to biological discovery with a potentially profound impact on genomics, pharmacogenomics, and proteomics. Microarrays have been used to study host-pathogen interactions, and recently this technology has been applied to investigate host-virus interactions. DNA arrays are used to monitor host alterations in several virus-induced cancers and upon infection with wild-type or modified viruses, or viral gene products. Alternatively, viral chips are used to characterize the transcriptional program of pathogenic viruses and in antiviral drug screening and drug resistance. With an aim to extend the use of this technology to ocular research, and specifically to study changes in host cell transcription in ocular adenovirus infection, we used a commercial array to compare adenovirus-infected human corneal cells to mock-infected cells. Of the 1176 genes analyzed, 72 genes associated with cell cycle regulation, apoptosis, oncogenesis, transcription, signaling, and inflammation were differentially regulated. In this review we summarize the use of DNA arrays in the study of viral infections and suggest potential uses of the technology in ocular viral pathogenesis research.
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Affiliation(s)
- K Natarajan
- Molecular Pathogenesis of Eye Infection Research Center, Dean A. McGee Eye Institute, Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, USA
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29
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Affiliation(s)
- Grant Trobridge
- Division of Hematology, University of Washington, Seattle, Washington 98195, USA
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30
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Kido K, Doerks A, Lochelt M, Flügel RM. Identification and functional characterization of an intragenic DNA binding site for the spumaretroviral trans-activator in the human p57Kip2 gene. J Biol Chem 2002; 277:12032-9. [PMID: 11815601 DOI: 10.1074/jbc.m108747200] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Expression of the human cyclin-dependent protein kinase inhibitor p57(Kip2) gene was previously shown to be specifically and strongly activated by the retroviral trans-activator Bel1 of human foamy virus by means of expression profiling, Northern, and Western blot analysis. Here we report that Bel1-mediated trans-activation was conferred by a Bel1 response element (BRE) located in the second exon of p57(Kip2). The intragenic Kip2-BRE was capable of trans-activating the luciferase reporter gene upon cotransfection with Bel1. In electrophoretic mobility shift assays using 293T nuclear extracts or a purified glutathione S-transferase (GST) small middle dotBel1 fusion protein, we identified the 55-nucleotide-long Kip2-BRE site that mainly consists of three direct repeats of 14-mers partially homologous to a functionally active BRE in the viral internal promoter. The specificity of the transactivator-DNA binding was shown by using mutated and shortened Kip2-BRE oligodeoxynucleotides in competition experiments with the authentic viral internal promoter and by Bel1-specific antibody that led to a supershift of the nuclear protein small middle dotKip2-BRE and GST small middle dotBel1 small middle dotKip2-BRE complex. The data indicate that Bel1 can directly bind to BRE sites. The cellular Kip2-BRE can be used to predict those human genes that are directly or indirectly activated by the Bel1 trans-activator.
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Affiliation(s)
- Kenji Kido
- Division of Retroviral Gene Expression, Research Program Applied Tumor Virology, German Cancer Research Center, Im Neuenheimer Feld 242, 69009 Heidelberg, Germany
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31
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Hess S, Rheinheimer C, Tidow F, Bartling G, Kaps C, Lauber J, Buer J, Klos A. The reprogrammed host: Chlamydia trachomatis-induced up-regulation of glycoprotein 130 cytokines, transcription factors, and antiapoptotic genes. Arthritis Rheum 2001; 44:2392-401. [PMID: 11665982 DOI: 10.1002/1529-0131(200110)44:10<2392::aid-art404>3.0.co;2-i] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
OBJECTIVE Infection with Chlamydia trachomatis is a known cause of sexually transmitted diseases, eye infections (including trachoma), and reactive arthritis (ReA). Because the mechanisms of Chlamydia-induced changes leading to ReA are poorly defined, this study sought to identify the target genes involved at the molecular level. METHODS Chlamydia-induced changes in host cells were investigated by combining a screening technique, which utilized complementary DNA arrays on C trachomatis-infected and mock-infected epithelial HeLa cells, with real-time reverse transcription-polymerase chain reaction or enzyme-linked immunosorbent assay of gene products. Some responses were additionally demonstrated on human primary chondrocytes and a human synovial fibroblast cell line, both of which served as model cells for ReA. RESULTS Eighteen genes (of 1,176) were found to be up-regulated after 24 hours of infection with this obligate intracellular bacterium, among them the glycoprotein 130 family members IL-11 and LIF, the chemokine gene MIP2-alpha, the transcription factor genes EGR1, ETR101, FRA1, and c-jun, the apoptosis-related genes IEX-1L and MCL-1, adhesion molecule genes such as ICAM1, and various other functionally important genes. In the context of this rheumatic disease, the cytokines and transcription factors seem to be especially involved, since various connections to chondrocytes, synoviocytes, bone remodeling, joint pathology, and other rheumatic diseases have been demonstrated. CONCLUSION Infection with C trachomatis seems to reprogram the host cells (independent of activation by lipopolysaccharide or other ultraviolet-resistant bacterial components) at various key positions that act as intra- or intercellular switches, suggesting that these changes and similar Chlamydia-induced functional alterations constitute an important basis of the pathogenic inflammatory potential of these cells in ReA. Our results suggest that this approach is generally useful for the broad analysis of host-pathogen interactions involving obligate intracellular bacteria, and for the identification of target genes for therapeutic intervention in this rheumatic disease.
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Affiliation(s)
- S Hess
- Medical School Hannover, Germany
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32
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Abstract
Foamy viruses (FV) are complex retroviruses with additional bel genes located between env and the 3' long-terminal repeat. The functions of the bel 2 and bet genes are unknown and both are dispensable for replication of the prototypic human foamy virus in cell cultures. We examined the function(s) of bel 2 and bet of the distantly related feline foamy virus (FFV) in the proviral context. Mutagenesis was used to alter the Bel 2 and Bet or to abrogate their expression. The Bel 2/Bet mutants showed a 1000-fold reduced viral titer in feline kidney cells; in human 293T cells, viral titer was only about 10-fold reduced compared to wild-type FFV. In both cell types, the Bel 2/Bet mutations resulted in a reduced release of FFV particles. The results indicate that FFV Bet is required for efficient virus replication. The functions of the Bel 2 and Bet proteins are discussed.
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Affiliation(s)
- A Alke
- Abteilung Retrovirale Genexpression, Forschungsschwerpunkt Angewandte Tumorvirologie, Deutsches Krebforschungszentrum, Heidelberg, Germany
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33
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Geiss GK, An MC, Bumgarner RE, Hammersmark E, Cunningham D, Katze MG. Global impact of influenza virus on cellular pathways is mediated by both replication-dependent and -independent events. J Virol 2001; 75:4321-31. [PMID: 11287581 PMCID: PMC114177 DOI: 10.1128/jvi.75.9.4321-4331.2001] [Citation(s) in RCA: 105] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Influenza virus, the causative agent of the common flu, is a worldwide health problem with significant economic consequences. Studies of influenza virus biology have revealed elaborate mechanisms by which the virus interacts with its host cell as it inhibits the synthesis of cellular proteins, evades the innate antiviral response, and facilitates production of viral RNAs and proteins. With the advent of DNA array technology it is now possible to obtain a large-scale view of how viruses alter the environment within the host cell. In this study, the cellular response to influenza virus infection was examined by monitoring the steady-state mRNA levels for over 4,600 cellular genes. Infections with active and inactivated influenza viruses identified changes in cellular gene expression that were dependent on or independent of viral replication, respectively. Viral replication resulted in the downregulation of many cellular mRNAs, and the effect was enhanced with time postinfection. Interestingly, several genes involved in protein synthesis, transcriptional regulation, and cytokine signaling were induced by influenza virus replication, suggesting that some may play essential or accessory roles in the viral life cycle or the host cell's stress response. The gene expression pattern induced by inactivated viruses revealed induction of the cellular metallothionein genes that may represent a protective response to virus-induced oxidative stress. Genome-scale analyses of virus infections will help us to understand the complexities of virus-host interactions and may lead to the discovery of novel drug targets or antiviral therapies.
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Affiliation(s)
- G K Geiss
- Department of Microbiology, School of Medicine, University of Washington, Seattle 98195, USA.
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