1
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Wang D, Dai W, Wu J, Wang J. Improving transcriptional activity of human cytomegalovirus major immediate-early promoter by mutating NF-κB binding sites. Protein Expr Purif 2017; 142:16-24. [PMID: 28941824 DOI: 10.1016/j.pep.2017.09.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Revised: 09/12/2017] [Accepted: 09/18/2017] [Indexed: 01/11/2023]
Abstract
Many mammalian gene expression vectors express the transferred genes under the control of the cytomegalovirus (CMV) major immediate-early promoter (MIEP). The human MIEP has been known as the strongest promoter in mammalian cells and utilized widely in mammalian expression systems. There are four NF-κB binding sites (named as κBs) in the human MIEP. In this study, we have constructed multiple mutated MIEPs by changing the natural κBs in the human MIEP into the high-affinity artificial sequences that were in vitro selected by using systematic evolution of ligands by exponential enrichment (SELEX) and predicted by bioinformatics. With various transcriptional activity evaluations, we found three mutated MIEPs with the transcriptional activity higher than the wild-type MIEP, which should be useful and widely applicable in many mammalian transgene expression fields such as gene engineering, gene therapy and gene editing. This study provides a useful approach for promoter engineering in biotechnology. This study also produced a series of mutated MIEPs with various transcriptional activities, which may be used for the fine control of gene expression output in the future synthetic biology.
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Affiliation(s)
- Danyang Wang
- State Key Laboratory of Bioelectronics, Southeast University, Nanjing 210096, China
| | - Wei Dai
- State Key Laboratory of Bioelectronics, Southeast University, Nanjing 210096, China
| | - Jian Wu
- State Key Laboratory of Bioelectronics, Southeast University, Nanjing 210096, China
| | - Jinke Wang
- State Key Laboratory of Bioelectronics, Southeast University, Nanjing 210096, China.
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2
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Oberstein A, Perlman DH, Shenk T, Terry LJ. Human cytomegalovirus pUL97 kinase induces global changes in the infected cell phosphoproteome. Proteomics 2015; 15:2006-22. [PMID: 25867546 DOI: 10.1002/pmic.201400607] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Revised: 03/12/2015] [Accepted: 04/09/2015] [Indexed: 12/12/2022]
Abstract
Replication of human cytomegalovirus (HCMV) is regulated in part by cellular kinases and the single viral Ser/Thr kinase, pUL97. The virus-coded kinase augments the replication of HCMV by enabling nuclear egress and altering cell cycle progression. These roles are accomplished through direct phosphorylation of nuclear lamins and the retinoblastoma protein, respectively. In an effort to identify additional pUL97 substrates, we analyzed the phosphoproteome of SILAC-labeled human fibroblasts during infection with either wild-type HCMV or a pUL97 kinase-dead mutant virus. Phosphopeptides were enriched over a titanium dioxide matrix and analyzed by high-resolution MS. We identified 157 unambiguous phosphosites from 106 cellular and 17 viral proteins whose phosphorylation required UL97. Analysis of peptides containing these sites allowed the identification of several candidate pUL97 phosphorylation motifs, including a completely novel phosphorylation motif, LxSP. Substrates harboring the LxSP motif were enriched in nucleocytoplasmic transport functions, including a number of components of the nuclear pore complex. These results extend the known functions of pUL97 and suggest that modulation of nuclear pore function may be important during HCMV replication.
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Affiliation(s)
- Adam Oberstein
- Department of Molecular Biology, Princeton University, Princeton, NJ, USA
| | - David H Perlman
- Department of Molecular Biology, Princeton University, Princeton, NJ, USA
| | - Thomas Shenk
- Department of Molecular Biology, Princeton University, Princeton, NJ, USA
| | - Laura J Terry
- Department of Molecular Biology, Princeton University, Princeton, NJ, USA
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3
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Human kinome profiling identifies a requirement for AMP-activated protein kinase during human cytomegalovirus infection. Proc Natl Acad Sci U S A 2012; 109:3071-6. [PMID: 22315427 DOI: 10.1073/pnas.1200494109] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Human cytomegalovirus (HCMV) modulates numerous cellular signaling pathways. Alterations in signaling are evident from the broad changes in cellular phosphorylation that occur during HCMV infection and from the altered activity of multiple kinases. Here we report a comprehensive RNAi screen, which predicts that 106 cellular kinases influence growth of the virus, most of which were not previously linked to HCMV replication. Multiple elements of the AMP-activated protein kinase (AMPK) pathway scored in the screen. As a regulator of carbon and nucleotide metabolism, AMPK is poised to activate many of the metabolic pathways induced by HCMV infection. An AMPK inhibitor, compound C, blocked a substantial portion of HCMV-induced metabolic changes, inhibited the accumulation of all HCMV proteins tested, and markedly reduced the production of infectious progeny. We propose that HCMV requires AMPK or related activity for viral replication and reprogramming of cellular metabolism.
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4
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Filippakis H, Dimitropoulou P, Eliopoulos AG, Spandidos DA, Sourvinos G. The enhanced host-cell permissiveness of human cytomegalovirus is mediated by the Ras signaling pathway. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2011; 1813:1872-82. [PMID: 21782855 DOI: 10.1016/j.bbamcr.2011.07.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2011] [Revised: 07/08/2011] [Accepted: 07/08/2011] [Indexed: 12/14/2022]
Abstract
Human cytomegalovirus utilizes cellular signal transduction pathways to activate viral or cellular transcription factors involved in the control of viral gene expression and DNA replication. In the present study, we demonstrate that Harvey-ras-transformed cells show increased permissiveness to human cytomegalovirus when compared to their parental non-transformed cells. Both the progeny viral yield and the protein levels were elevated in the human cytomegalovirus-infected Harvey-ras-transformed cells requiring active viral gene replication, as shown by the infection with UV-inactivated human cytomegalovirus. Inhibition of Ras or of key molecules of the Ras pathway, effectively suppressed viral infection in the Harvey-ras-transformed cells. On a cellular level, the human cytomegalovirus-infected Harvey-ras-transformed cells formed larger cellular foci, which were significantly higher in number, compared to the uninfected cells and preferentially recruited human cytomegalovirus virions, thereby incriminating human cytomegalovirus infection for the increased transformation of these cells. Furthermore, proliferation assays revealed a higher rate for the human cytomegalovirus-infected Harvey-ras-transformed cells compared to mock-infected cells, whereas human cytomegalovirus infection had no considerable effect on the proliferation of the non-transformed cells. Higher susceptibility to apoptosis was also detected in the human cytomegalovirus-infected ras-transformed cells, which in combination with the higher progeny virus reveals a mode by which human cytomegalovirus achieves efficient spread of infection in the cells expressing the oncogenic Harvey-ras (12V) gene. Collectively, our data suggest that human cytomegalovirus employs the host-cell Ras signaling pathway to ensue viral expression and ultimately successful propagation. Transformed cells with an activated Ras signaling pathway are therefore particularly susceptible to human cytomegalovirus infection.
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5
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Heat shock enhances CMV-IE promoter-driven metabotropic glutamate receptor expression and toxicity in transfected cells. Neuropharmacology 2011; 60:1292-300. [PMID: 21241715 DOI: 10.1016/j.neuropharm.2011.01.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2010] [Revised: 11/18/2010] [Accepted: 01/10/2011] [Indexed: 11/20/2022]
Abstract
In CHO-K1 cells, heat shock strongly activated reporter-gene expression driven by the cytomegalovirus immediate-early (CMV-IE) promoter from adenoviral and plasmid vectors. Heat shock treatment (2h at 42.5 °C) significantly enhanced the promoter DNA-binding activity in nuclear extracts. In CHO cells expressing mGluR1a and mGluR5a receptors under the control of the CMV promoter, heat shock increased receptor protein expression, mRNA levels and receptor function estimated by measurement of PI hydrolysis, intracellular Ca²+ and cAMP. Hyperthermia increased average amplitudes of Ca²+ responses, the number of responding cells, and revealed the toxic properties of mGluR1a receptor. Heat shock also effectively increased the expression of EGFP. Hence, heat shock effects on mGluR expression and function in CHO cells may be attributed to the activation of the CMV promoter. Moreover, this effect was not limited to CHO cells as heat shock also increased EGFP expression in PC-12 and HEK293 cells. Heat shock treatment may be a useful tool to study the function of proteins expressed in heterologous systems under control of the CMV promoter. It may be especially valuable for increasing protein expression in transient transfections, for enhancing receptor expression in drug screening applications and to control the expression of proteins endowed with toxic properties. This article is part of a Special Issue entitled 'Trends in neuropharmacology: in memory of Erminio Costa'.
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6
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Yi HA, Kim MS, Jang SY, Lee YM, Ahn JH, Lee CH. Cellular signals involved in cyclooxygenase-2 expression induced by human cytomegalovirus. Virus Res 2009; 146:89-96. [PMID: 19748535 DOI: 10.1016/j.virusres.2009.09.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2009] [Revised: 08/31/2009] [Accepted: 09/03/2009] [Indexed: 10/20/2022]
Abstract
Cyclooxygenase (COX)-2 plays an important role in inflammatory reaction and human cytomegalovirus (HCMV) is known to induce COX-2 gene expression. However, little is known for the mechanism of COX-2 gene expression by HCMV. In this study, three recently isolated HCMV strains including TB40/E and clinical isolates from Korean patients as well as highly laboratory adapted strain AD169 were used to stimulate COX-2 induction. Western blot analyses revealed that recently isolated HCMV strains induced COX-2 expression in human foreskin fibroblast (HFF) cells to higher levels than lab-adapted strain AD169. HCMV gene expression was not required for COX-2 induction since UV-inactivated virus was able to stimulate COX-2 gene expression during immediate early infection. Moreover, when HCMV-infected HFF cells were transfected with small interfering RNA for major immediate early (MIE) genes, HCMV-induced COX-2 expression was not abrogated, suggesting that HCMV MIE genes are not needed for COX-2 expression. In order to understand the signal pathways involved in COX-2 gene expression induced by HCMV, selective inhibitors were used. When HCMV-infected HFF cells were treated with epidermal growth factor receptor (EGFR) kinase inhibitors and c-Raf/mitogen-activated protein kinases (MAPK, MEK) 1/2 inhibitors, HCMV-induced COX-2 expression was diminished. However, COX-2 expression by HCMV infection was not inhibited if HCMV-infected HFF cells were treated with inhibitors of phosphatidylinositol-3-kinase, c-Jun N-terminal kinase, nuclear factor kappa B, p-38 MAPK and Rho-associated protein kinase. We concluded that EGFRK, Raf, MEK1/2 and extracellular signal-regulated kinases (ERK 1/2) pathway may participate in the COX-2 mediated inflammatory response to HCMV infection.
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Affiliation(s)
- Hyun Ah Yi
- Department of Microbiology, Chungbuk National University, Cheongju, Chungbuk 361-763, South Korea
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7
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Alvarez-Castelao B, Martín-Guerrero I, García-Orad Á, Castaño JG. Cytomegalovirus promoter up-regulation is the major cause of increased protein levels of unstable reporter proteins after treatment of living cells with proteasome inhibitors. J Biol Chem 2009; 284:28253-28262. [PMID: 19679666 DOI: 10.1074/jbc.m109.004101] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Fluorescent unstable proteins obtained by the fusion of a fluorescent protein coding sequence with specific amino acid sequences that promote its fast degradation have become popular to gauge the activity of the ubiquitin/proteasome system in living cells. The steady-state levels of expression of these unstable proteins is low in agreement with their short half-lives, and they accumulate in the cell upon treatment with proteasome inhibitors. We show here that this accumulation is mainly due to transcriptional up-regulation of the cytomegalovirus promoter by proteasome inhibitors and mediated, at least in part, by AP1 transactivation. These simple facts put under quarantine conclusions reached about the activity of the ubiquitin/proteasome pathway in animal cells in culture or in transgenic mice, where popular cytomegalovirus-driven constructs are used, as transcriptional regulation of the expression of the reporter protein construct and not degradation of the unstable protein by the ubiquitin/proteasome system may contribute significantly to the interpretation of the results observed.
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Affiliation(s)
- Beatriz Alvarez-Castelao
- Departamento de Bioquímica, Instituto de Investigaciones Biomédicas "Alberto Sols," Universidad Autónoma de Madrid y Consejo Superior de Investigaciones Científicas (UAM-CSIC) y Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Facultad de Medicina UAM, 28029 Madrid, Spain
| | - Idoia Martín-Guerrero
- Departamento de Genética, Antropología Física y Fisiología Animal, Facultad de Medicina, Universidad del País Vasco (UPV/EHU), 48940 Leioa, Spain
| | - África García-Orad
- Departamento de Genética, Antropología Física y Fisiología Animal, Facultad de Medicina, Universidad del País Vasco (UPV/EHU), 48940 Leioa, Spain
| | - José G Castaño
- Departamento de Bioquímica, Instituto de Investigaciones Biomédicas "Alberto Sols," Universidad Autónoma de Madrid y Consejo Superior de Investigaciones Científicas (UAM-CSIC) y Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Facultad de Medicina UAM, 28029 Madrid, Spain.
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8
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Moon JS, Lee MY, Park SW, Han WK, Hong SW, Ahn JH, Kim KS. Androgen-dependent activation of human cytomegalovirus major immediate-early promoter in prostate cancer cells. Prostate 2008; 68:1450-60. [PMID: 18615458 DOI: 10.1002/pros.20817] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
BACKGROUND Human cytomegalovirus (HCMV) major immediate early (MIE) promoter, which is involved in viral reactivation, is specifically activated by androgen in LNCaP prostate cancer cells. METHODS Androgen-dependent transcriptional activities of the HCMV MIE promoter were measured by transient transfection assay. Expression levels of genes related to protein kinase A (PKA)-signaling pathway was measured by RT-PCR. RESULTS Activation of the HCMV MIE promoter by androgen results from an increase in PKA activities. The expression level of PKA catalytic (C) subunit beta transcript variant 2 (PKA-C beta 2) was decreased by serum deprivation and was increased by R1881 treatment, in a pattern similar to changes of the HCMV MIE promoter activities. Furthermore the exogenous expression of PKA-C beta 2 strongly activated the HCMV MIE promoter, indicating that regulation of the PKA-C beta 2 expression might be a direct upstream factor in the HCMV MIE promoter regulation by androgen in LNCaP cells. CONCLUSIONS The data elucidated the mechanisms by which androgen activates PKA in androgen-dependent prostate cancer cells, resulting in activation of the HCMV MIE promoter. These results support the possibility that activation of the HCMV MIE promoter by androgen in the prostate could cause the productive infection, which might contribute to oncomodulation in prostate cancers.
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Affiliation(s)
- Jong-Seok Moon
- Department of Biochemistry and Molecular Biology, Institute of Genetic Science, Center for Chronic Metabolic Disease Research, Brain Korea 21 Project for Medical Science, Yonsei University, College of Medicine, Seodaemungu, Seoul, Korea
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9
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Le VTK, Trilling M, Zimmermann A, Hengel H. Mouse cytomegalovirus inhibits beta interferon (IFN-beta) gene expression and controls activation pathways of the IFN-beta enhanceosome. J Gen Virol 2008; 89:1131-1141. [PMID: 18420790 DOI: 10.1099/vir.0.83538-0] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
We have investigated beta interferon (IFN-beta) and IFN-alpha4 gene expression and activation of related transcription factors in mouse cytomegalovirus (MCMV)-infected fibroblasts. mRNA analysis demonstrated an initial phase of IFN gene induction upon MCMV infection, which was followed by a sustained MCMV-mediated simultaneous downregulation of IFN-beta and IFN-alpha4 gene expression. The induction of IFN transcription resulted from the activation of the components of the IFN-beta enhanceosome, i.e. IFN regulatory factor (IRF) 3, nuclear factor (NF)-kappaB, activating transcription factor (ATF)-2 and c-Jun. Activation of the transcription factors occurred rapidly and in a sequential order upon infection, but only lasted a while. As a consequence, IFN-alpha/beta gene expression became undetectable 6 h post-infection and throughout the MCMV replication cycle. This effect is based on an active interference since restimulation of IFN gene induction by further external stimuli (e.g. Sendai virus infection) was completely abolished. This inhibition required MCMV gene expression and was not observed in cells infected with UV-inactivated MCMV virions. The efficiency of inhibition is achieved by a concerted blockade of IkappaBalpha degradation and a lack of nuclear accumulation of IRF3 and ATF-2/c-Jun. Using an MCMV mutant lacking pM27, a signal transducer and activator of transcription (STAT) 2-specific inhibitor of Jak/STAT signalling, we found that the initial phase of IFN induction and the subsequent inhibition does not depend on the positive-IFN feedback loop. Our findings indicate that the MCMV-mediated downregulation of IFN transcription in fibroblasts relies on a large arsenal of inhibitory mechanisms targeting each pathway that contributes to the multiprotein enhanceosome complex.
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Affiliation(s)
- Vu Thuy Khanh Le
- Heinrich-Heine-Universität Düsseldorf, Institut für Virologie, 40225 Düsseldorf, Germany
| | - Mirko Trilling
- Heinrich-Heine-Universität Düsseldorf, Institut für Virologie, 40225 Düsseldorf, Germany
| | - Albert Zimmermann
- Heinrich-Heine-Universität Düsseldorf, Institut für Virologie, 40225 Düsseldorf, Germany
| | - Hartmut Hengel
- Heinrich-Heine-Universität Düsseldorf, Institut für Virologie, 40225 Düsseldorf, Germany
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10
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Ramanathan M, Haskó G, Leibovich SJ. Analysis of signal transduction pathways in macrophages using expression vectors with CMV promoters: a cautionary tale. Inflammation 2007; 29:94-102. [PMID: 16865543 DOI: 10.1007/s10753-006-9005-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The cytomegalovirus (CMV) major immediate-early promoter is a strong promoter used for both in vitro and in vivo expression of proteins in signal transduction and gene therapy studies. CMV activity is induced by external stimuli such as endotoxin from Gram-negative bacteria (LPS), TNF-alpha and phorbol esters. This inducibility poses problems when this promoter is used to drive the expression of either wild type or dominant negative mutated proteins as tools in signal transduction studies. This report draws attention to the problem associated with this widely used approach. The role of NF-kappaB and Hypoxia Inducible Factor-1alpha (HIF-1alpha) in the transcriptional regulation of Vascular Endothelial Growth Factor (VEGF) in macrophages was investigated using CMV-promoter-driven expression of either wild type or dominant negative proteins involved in these pathways. Difficulties encountered while interpreting the data due to the inducibility of the CMV promoter by LPS are highlighted in this report and provide a cautionary note for the evaluation of data acquired using this approach.
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Affiliation(s)
- Madhuri Ramanathan
- Department of Cell Biology and Molecular Medicine & The Cardiovascular Research Institute, New Jersey Medical School, University of Medicine and Dentistry of New Jersey, 185 South Orange Avenue, Newark, NJ 07103, USA
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11
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Lee Y, Sohn WJ, Kim DS, Kwon HJ. NF-kappaB- and c-Jun-dependent regulation of human cytomegalovirus immediate-early gene enhancer/promoter in response to lipopolysaccharide and bacterial CpG-oligodeoxynucleotides in macrophage cell line RAW 264.7. ACTA ACUST UNITED AC 2004; 271:1094-105. [PMID: 15009188 DOI: 10.1111/j.1432-1033.2004.04011.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The cytomegalovirus immediate-early (CMV IE) gene enhancer/promoter regulates the expression of immediate-early gene products and initiation of CMV replication. TNF-alpha and lipopolysaccharide (LPS) strongly activate the promoter, possibly involving NF-kappaB. CpG-oligodeoxynucleotides (CpG-ODNs), which contain unmethylated CpG dinucleotides in the context of particular base sequences, have gained attention because of their stimulating effects, via NF-kappaB, which have a strong innate immune response. To study the effects of LPS and CpG-ODNs, as well as the mechanisms of their actions regarding CMV IE enhancer/promoter activation, we used a macrophage cell line, RAW 264.7. Stimulation of the cells with LPS or CpG-ODNs resulted in the activation of the CMV IE enhancer/promoter. We examined the involvement of NF-kappaB and c-Jun transcription factors by promoter deletion/site-specific mutation analysis and ectopic expression, and found them to have additive effects. Involvement of myeloid differentiation protein, an upstream regulator of NF-kappaB and c-Jun, was also investigated. Experimental results indicate that both LPS-induced and CpG-ODN-induced activations of CMV IE enhancer/promoter are mediated by Toll-like receptor signaling molecules. Several lines of evidence suggest the potential contribution of bacterial infection in CMV reactivation along with the potential application of CpG-ODNs in gene therapy as a stimulator for the optimal expression of target genes under the control of the CMV IE enhancer/promoter.
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MESH Headings
- Adaptor Proteins, Signal Transducing
- Animals
- Antigens, Differentiation/genetics
- Antigens, Differentiation/metabolism
- Cell Line
- Cytomegalovirus/drug effects
- Cytomegalovirus/genetics
- Enhancer Elements, Genetic/drug effects
- Enhancer Elements, Genetic/genetics
- Genes, Immediate-Early/drug effects
- Genes, Immediate-Early/genetics
- Humans
- I-kappa B Proteins/metabolism
- Lipopolysaccharides/pharmacology
- Macrophages/drug effects
- Macrophages/metabolism
- Mice
- Myeloid Differentiation Factor 88
- NF-KappaB Inhibitor alpha
- NF-kappa B/antagonists & inhibitors
- NF-kappa B/genetics
- NF-kappa B/metabolism
- Oligodeoxyribonucleotides/pharmacology
- Plasmids/genetics
- Promoter Regions, Genetic/drug effects
- Promoter Regions, Genetic/genetics
- Proto-Oncogene Proteins c-jun/genetics
- Proto-Oncogene Proteins c-jun/metabolism
- Receptors, Immunologic/genetics
- Receptors, Immunologic/metabolism
- Sequence Deletion/genetics
- Transcription Factor RelA
- Transfection
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Affiliation(s)
- Younghee Lee
- Cell Biology Laboratory, Korea Research Institute of Bioscience and Biotechnology, Yusong, Daejon, Korea
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12
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Benedict CA, Angulo A, Patterson G, Ha S, Huang H, Messerle M, Ware CF, Ghazal P. Neutrality of the canonical NF-kappaB-dependent pathway for human and murine cytomegalovirus transcription and replication in vitro. J Virol 2004; 78:741-50. [PMID: 14694106 PMCID: PMC368812 DOI: 10.1128/jvi.78.2.741-750.2004] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2003] [Accepted: 09/26/2003] [Indexed: 02/08/2023] Open
Abstract
Cytomegalovirus (CMV) is known to rapidly induce activation of nuclear factor kappaB (NF-kappaB) after infection of fibroblast and macrophage cells. NF-kappaB response elements are present in the enhancer region of the CMV major immediate-early promoter (MIEP), and activity of the MIEP is strongly upregulated by NF-kappaB in transient-transfection assays. Here we investigate whether the NF-kappaB-dependent pathway is required for initiating or potentiating human and murine CMV replication in vitro. We show that expression of a dominant negative mutant of the inhibitor of NF-kappaB-alpha (IkappaBalphaM) does not alter the replication kinetics of human or mouse CMV in cultured cells. In addition, mouse embryo fibroblasts genetically deficient for p65/RelA actually showed elevated levels of MCMV replication. Mutation of all NF-kappaB response elements within the enhancer of the MIEP in a recombinant mouse CMV containing the human MIEP (hMCMV-ES), which we have previously shown to replicate in murine fibroblasts with kinetics equivalent to that of wild-type mouse CMV, did not negatively affect replication in fibroblasts. Taken together, these data show that, for CMV replication in cultured fibroblasts activation of the canonical NF-kappaB pathway and binding of NF-kappaB to the MIEP are dispensable, and in the case of p65 may even interfere, thus uncovering a previously unrecognized level of complexity in the host regulatory network governing MIE gene expression in the context of a viral infection.
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Affiliation(s)
- Chris A Benedict
- La Jolla Institute of Allergy and Immunology, San Diego, California 92007, USA
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13
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Casarosa P, Gruijthuijsen YK, Michel D, Beisser PS, Holl J, Fitzsimons CP, Verzijl D, Bruggeman CA, Mertens T, Leurs R, Vink C, Smit MJ. Constitutive Signaling of the Human Cytomegalovirus-encoded Receptor UL33 Differs from That of Its Rat Cytomegalovirus Homolog R33 by Promiscuous Activation of G Proteins of the Gq, Gi, and Gs Classes. J Biol Chem 2003; 278:50010-23. [PMID: 14522997 DOI: 10.1074/jbc.m306530200] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The human cytomegalovirus (HCMV) UL33 gene is conserved among all beta-herpesviruses and encodes a protein that shows sequence similarity with chemokine receptors belonging to the family of G protein-coupled receptors. Here, we show that HCMV UL33 is predominantly transcribed as a spliced mRNA of which the 5' terminus is localized 55 bp upstream of the start codon. Like its homolog from rat cytomegalovirus (RCMV), R33, UL33 activates multiple signaling pathways in a ligand-independent manner. Although both receptors constitutively activate phospholipase C via G(q/11), and partially via G(i/o)-mediated pathways, they exhibit profound differences in the modulation of cAMP-responsive element (CRE) activation. R33 constitutively inhibits, whereas UL33 constitutively enhances CRE-mediated transcription. For R33, the inhibition of CRE-driven transcription is entirely G(i/o)-mediated. For UL33, however, CRE-mediated transcription is modulated not only through coupling to Galpha(i/o) but also through coupling to Galphas. In addition, UL33 was found to enhance CRE activation through the Rho/p38 pathway, via Gbetagamma. Interestingly, by studying chimeric UL33/R33 proteins, we found the C-terminal cytoplasmic tail of UL33, but not that of R33, to be responsible for the activation of G(i/o) proteins. A UL33-deficient variant of HCMV was generated to analyze UL33-signaling properties in a physiologically relevant model system. Data obtained with infected cells show that HCMV induces CRE activation, and this effect is, at least in part, dependent on UL33 expression. Taken together, our data indicate that constitutive signaling of UL33 differs from that of R33 by promiscuous activation of G proteins of the Gq, G(i/o), as well as Gs class. Thus, HCMV may effectively use UL33 to orchestrate multiple signaling networks within infected cells.
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MESH Headings
- Amino Acid Sequence
- Animals
- Base Sequence
- COS Cells
- Cell Line, Tumor
- Cells, Cultured
- Codon
- Cyclic AMP Response Element Modulator
- DNA, Complementary/metabolism
- DNA-Binding Proteins/metabolism
- Dose-Response Relationship, Drug
- Fibroblasts/metabolism
- GTP-Binding Protein alpha Subunits, Gi-Go/metabolism
- GTP-Binding Protein alpha Subunits, Gq-G11/metabolism
- GTP-Binding Protein alpha Subunits, Gs/metabolism
- GTP-Binding Protein beta Subunits/metabolism
- GTP-Binding Protein gamma Subunits/metabolism
- Gene Deletion
- Green Fluorescent Proteins
- Humans
- Luminescent Proteins/metabolism
- Microscopy, Confocal
- Models, Genetic
- Molecular Sequence Data
- Mutagenesis, Site-Directed
- Mutation
- Plasmids/metabolism
- Protein Binding
- Protein Structure, Secondary
- Protein Structure, Tertiary
- Rats
- Receptors, Chemokine/chemistry
- Receptors, Chemokine/metabolism
- Receptors, G-Protein-Coupled/chemistry
- Receptors, G-Protein-Coupled/metabolism
- Repressor Proteins
- Sequence Homology, Amino Acid
- Signal Transduction
- Species Specificity
- Time Factors
- Viral Proteins/chemistry
- Viral Proteins/metabolism
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Affiliation(s)
- Paola Casarosa
- Leiden/Amsterdam Center for Drug Research, Division of Medicinal Chemistry, Faculty of Chemistry, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands
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Kronschnabl M, Stamminger T. Synergistic induction of intercellular adhesion molecule-1 by the human cytomegalovirus transactivators IE2p86 and pp71 is mediated via an Sp1-binding site. J Gen Virol 2003; 84:61-73. [PMID: 12533701 DOI: 10.1099/vir.0.18703-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Human cytomegalovirus (HCMV) infection of transplant recipients is frequently associated with allograft vasculopathy and rejection. One potential mechanism is vascular injury from HCMV-triggered, immunologically mediated processes. HCMV infection has been shown to increase the expression of intercellular adhesion molecule-1 (ICAM-1). The objective of this study was to determine the molecular basis of HCMV-enhanced ICAM-1 gene expression. Transient transfection experiments identified the IE2p86 protein as a potent activator of the ICAM-1 promoter. The tegument protein pp71 showed a strong synergistic effect on IE2p86-mediated ICAM-1 promoter activation. Mutagenesis experiments defined a DNA element from -110 to -42 relative to the transcription start site as responsive for IE2p86. Further point mutations within this DNA element identified an Sp1-binding site that was essential for strong synergistic activation by IE2p86 and pp71. To confirm the activation of ICAM-1 gene expression, human fibroblasts (HFF) as well as endothelial cells (HUVEC) were infected with recombinant IE2p86- and pp71-expressing baculoviruses, respectively. In FACS analysis, a synergistic induction of ICAM-1 was detectable when cells were co-infected with the two recombinant baculoviruses. These findings clearly demonstrate that IE2p86 and pp71 are crucial regulatory factors for HCMV-induced ICAM-1 upregulation.
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Affiliation(s)
- Martina Kronschnabl
- Institut für Klinische und Molekulare Virologie, Schlossgarten 4, 91054 Erlangen, Germany
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- Institut für Klinische und Molekulare Virologie, Schlossgarten 4, 91054 Erlangen, Germany
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