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Hong YM, Min SY, Kim D, Kim S, Seo D, Lee KH, Han SH. Human MicroRNAs Attenuate the Expression of Immediate Early Proteins and HCMV Replication during Lytic and Latent Infection in Connection with Enhancement of Phosphorylated RelA/p65 (Serine 536) That Binds to MIEP. Int J Mol Sci 2022; 23:ijms23052769. [PMID: 35269913 PMCID: PMC8911160 DOI: 10.3390/ijms23052769] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Revised: 02/24/2022] [Accepted: 02/28/2022] [Indexed: 02/05/2023] Open
Abstract
Attenuating the expression of immediate early (IE) proteins is essential for controlling the lytic replication of human cytomegalovirus (HCMV). The human microRNAs (hsa-miRs), miR-200b-3p and miR-200c-3p, have been identified to bind the 3′-untranslated region (3′-UTR) of the mRNA encoding IE proteins. However, whether hsa-miRs can reduce IE72 expression and HCMV viral load or exhibit a crosstalk with the host cellular signaling machinery, most importantly the NF-κB cascade, has not been evaluated. In this study, argonaute-crosslinking and immunoprecipitation-seq revealed that miR-200b-3p and miR-200c-3p bind the 3′-UTR of UL123, which is a gene that encodes IE72. The binding of these miRNAs to the 3′-UTR of UL123 was verified in transfected cells stably expressing GFP. We used miR-200b-3p/miR-200c-3p mimics to counteract the downregulation of these miRNA after acute HCMV infection. This resulted in reduced IE72/IE86 expression and HCMV VL during lytic infection. We determined that IE72/IE86 alone can inhibit the phosphorylation of RelA/p65 at the Ser536 residue and that p-Ser536 RelA/p65 binds to the major IE promoter/enhancer (MIEP). The upregulation of miR-200b-3p and miR-200c-3p resulted in the phosphorylation of RelA/p65 at Ser536 through the downregulation of IE, and the binding of the resultant p-Ser536 RelA/p65 to MIEP resulted in a decreased production of pro-inflammatory cytokines. Overall, miR-200b-3p and miR-200c-3p—together with p-Ser536 RelA/p65—can prevent lytic HCMV replication during acute and latent infection
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Affiliation(s)
- Yeon-Mi Hong
- Division of Infectious Disease, Department of Internal Medicine, Yonsei University College of Medicine, Seoul 06273, Korea; (Y.-M.H.); (S.Y.M.); (D.K.); (S.K.); (K.H.L.)
| | - Seo Yeon Min
- Division of Infectious Disease, Department of Internal Medicine, Yonsei University College of Medicine, Seoul 06273, Korea; (Y.-M.H.); (S.Y.M.); (D.K.); (S.K.); (K.H.L.)
| | - Dayeong Kim
- Division of Infectious Disease, Department of Internal Medicine, Yonsei University College of Medicine, Seoul 06273, Korea; (Y.-M.H.); (S.Y.M.); (D.K.); (S.K.); (K.H.L.)
| | - Subin Kim
- Division of Infectious Disease, Department of Internal Medicine, Yonsei University College of Medicine, Seoul 06273, Korea; (Y.-M.H.); (S.Y.M.); (D.K.); (S.K.); (K.H.L.)
| | - Daekwan Seo
- Severance Biomedical Science Institute, Yonsei University College of Medicine, Seoul 06273, Korea;
| | - Kyoung Hwa Lee
- Division of Infectious Disease, Department of Internal Medicine, Yonsei University College of Medicine, Seoul 06273, Korea; (Y.-M.H.); (S.Y.M.); (D.K.); (S.K.); (K.H.L.)
| | - Sang Hoon Han
- Division of Infectious Disease, Department of Internal Medicine, Yonsei University College of Medicine, Seoul 06273, Korea; (Y.-M.H.); (S.Y.M.); (D.K.); (S.K.); (K.H.L.)
- Correspondence: ; Tel.: +82-2-2019-3319; Fax: +82-2-3463-3882
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PDGFRα Enhanced Infection of Breast Cancer Cells with Human Cytomegalovirus but Infection of Fibroblasts Increased Prometastatic Inflammation Involving Lysophosphatidate Signaling. Int J Mol Sci 2021; 22:ijms22189817. [PMID: 34575976 PMCID: PMC8471290 DOI: 10.3390/ijms22189817] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 09/01/2021] [Accepted: 09/02/2021] [Indexed: 12/16/2022] Open
Abstract
Human cytomegalovirus (HCMV) infects 40-70% of adults in developed countries. HCMV proteins and DNA are detected in tumors and metastases, suggesting an association with increased invasion. We investigated HCMV infection in human breast cancer cell lines compared to fibroblasts, a component of tumors, and the role of platelet-derived growth factor receptor-α (PDGFRα). HCMV productively infected HEL299 fibroblasts and, to a lesser extent, Hs578T breast cancer cells. Infection of another triple-negative cell line, MDA-MB-231, and also MCF-7 cells, was extremely low. These disparate infection rates correlated with expression of PDGFRA, which facilitates HCMV uptake. Increasing PDGFRA expression in T-47D breast cancer and BCPAP thyroid cancer cells markedly increased HCMV infection. Conversely, HCMV infection decreased PDGFRA expression, potentially attenuating signaling through this receptor. HCMV infection of fibroblasts promoted the secretion of proinflammatory factors, whereas an overall decreased secretion of inflammatory factors was observed in infected Hs578T cells. We conclude that HCMV infection in tumors will preferentially target tumor-associated fibroblasts and breast cancer cells expressing PDGFRα. HCMV infection in the tumor microenvironment, rather than cancer cells, will increase the inflammatory milieu that could enhance metastasis involving lysophosphatidate.
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Tripathi V, Chatterjee KS, Das R. Non-covalent Interaction With SUMO Enhances the Activity of Human Cytomegalovirus Protein IE1. Front Cell Dev Biol 2021; 9:662522. [PMID: 34055792 PMCID: PMC8155523 DOI: 10.3389/fcell.2021.662522] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Accepted: 04/20/2021] [Indexed: 11/29/2022] Open
Abstract
Viruses interact with the host cellular pathways to optimize cellular conditions for replication. The Human Cytomegalovirus (HCMV) Immediate-Early protein 1 (IE1) is the first viral protein to express during infection. It is a multifunctional and conditionally essential protein for HCMV infection. SUMO signaling regulates several cellular pathways that are also targets of IE1. Consequently, IE1 exploits SUMO signaling to regulate these pathways. The covalent interaction of IE1 and SUMO (IE1-SUMOylation) is well studied. However, the non-covalent interactions between SUMO and IE1 are unknown. We report two SUMO-Interacting Motifs (SIMs) in IE1, one at the end of the core domain and another in the C-terminal domain. NMR titrations showed that IE1-SIMs bind to SUMO1 but not SUMO2. Two critical functions of IE1 are inhibition of SUMOylation of Promyelocytic leukemia protein (PML) and transactivation of viral promoters. Although the non-covalent interaction of IE1 and SUMO is not involved in the inhibition of PML SUMOylation, it contributes to the transactivation activity. The transactivation activity of IE1 was previously correlated to its ability to inhibit PML SUMOylation. Our results suggest that transactivation and inhibition of PML SUMOylation are independent activities of IE1.
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Affiliation(s)
- Vasvi Tripathi
- National Centre for Biological Sciences, Tata Institute of Fundamental Research (TIFR), Bengaluru, India
| | - Kiran Sankar Chatterjee
- National Centre for Biological Sciences, Tata Institute of Fundamental Research (TIFR), Bengaluru, India
| | - Ranabir Das
- National Centre for Biological Sciences, Tata Institute of Fundamental Research (TIFR), Bengaluru, India
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Regulation of the MIE Locus During HCMV Latency and Reactivation. Pathogens 2020; 9:pathogens9110869. [PMID: 33113934 PMCID: PMC7690695 DOI: 10.3390/pathogens9110869] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 10/19/2020] [Accepted: 10/20/2020] [Indexed: 12/20/2022] Open
Abstract
Human cytomegalovirus (HCMV) is a ubiquitous herpesviral pathogen that results in life-long infection. HCMV maintains a latent or quiescent infection in hematopoietic cells, which is broadly defined by transcriptional silencing and the absence of de novo virion production. However, upon cell differentiation coupled with immune dysfunction, the virus can reactivate, which leads to lytic replication in a variety of cell and tissue types. One of the mechanisms controlling the balance between latency and reactivation/lytic replication is the regulation of the major immediate-early (MIE) locus. This enhancer/promoter region is complex, and it is regulated by chromatinization and associated factors, as well as a variety of transcription factors. Herein, we discuss these factors and how they influence the MIE locus, which ultimately impacts the phase of HCMV infection.
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Tripathi V, Chatterjee KS, Das R. Casein kinase-2-mediated phosphorylation increases the SUMO-dependent activity of the cytomegalovirus transactivator IE2. J Biol Chem 2019; 294:14546-14561. [PMID: 31371453 DOI: 10.1074/jbc.ra119.009601] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Revised: 07/24/2019] [Indexed: 11/06/2022] Open
Abstract
Many viral factors manipulate the host post-translational modification (PTM) machinery for efficient viral replication. In particular, phosphorylation and SUMOylation can distinctly regulate the activity of the human cytomegalovirus (HCMV) transactivator immediate early 2 (IE2). However, the molecular mechanism of this process is unknown. Using various structural, biochemical, and cell-based approaches, here we uncovered that IE2 exploits a cross-talk between phosphorylation and SUMOylation. A scan for small ubiquitin-like modifier (SUMO)-interacting motifs (SIMs) revealed two SIMs in IE2, and a real-time SUMOylation assay indicated that the N-terminal SIM (IE2-SIM1) enhances IE2 SUMOylation up to 4-fold. Kinetic analysis and structural studies disclosed that IE2 is a SUMO cis-E3 ligase. We also found that two putative casein kinase 2 (CK2) sites adjacent to IE2-SIM1 are phosphorylated in vitro and in cells. The phosphorylation drastically increased IE2-SUMO affinity, IE2 SUMOylation, and cis-E3 activity of IE2. Additional salt bridges between the phosphoserines and SUMO accounted for the increased IE2-SUMO affinity. Phosphorylation also enhanced the SUMO-dependent transactivation activity and auto-repression activity of IE2. Together, our findings highlight a novel mechanism whereby SUMOylation and phosphorylation of the viral cis-E3 ligase and transactivator protein IE2 work in tandem to enable transcriptional regulation of viral gene.
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Affiliation(s)
- Vasvi Tripathi
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bengaluru-560065, India
| | - Kiran Sankar Chatterjee
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bengaluru-560065, India
| | - Ranabir Das
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bengaluru-560065, India
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Manandhar T, Hò GGT, Pump WC, Blasczyk R, Bade-Doeding C. Battle between Host Immune Cellular Responses and HCMV Immune Evasion. Int J Mol Sci 2019; 20:E3626. [PMID: 31344940 PMCID: PMC6695940 DOI: 10.3390/ijms20153626] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Revised: 07/18/2019] [Accepted: 07/19/2019] [Indexed: 12/16/2022] Open
Abstract
Human cytomegalovirus (HCMV) is ubiquitously prevalent. HCMV infection is typically asymptomatic and controlled by the immune system in healthy individuals, yet HCMV can be severely pathogenic for the fetus during pregnancy and in immunocompromised persons, such as transplant recipients or HIV infected patients. HCMV has co-evolved with the hosts, developed strategies to hide from immune effector cells and to successfully survive in the human organism. One strategy for evading or delaying the immune response is maintenance of the viral genome to establish the phase of latency. Furthermore, HCMV immune evasion involves the downregulation of human leukocyte antigens (HLA)-Ia molecules to hide infected cells from T-cell recognition. HCMV expresses several proteins that are described for downregulation of the HLA class I pathway via various mechanisms. Here, we review the wide range of immune evasion mechanisms of HCMV. Understanding the mechanisms of HCMV immune evasion will contribute to the development of new customized therapeutic strategies against the virus.
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Affiliation(s)
- Trishna Manandhar
- Institute for Transfusion Medicine, Hannover Medical School, 30625 Hannover, Germany
| | - Gia-Gia T Hò
- Institute for Transfusion Medicine, Hannover Medical School, 30625 Hannover, Germany
| | - Wiebke C Pump
- Institute for Transfusion Medicine, Hannover Medical School, 30625 Hannover, Germany
| | - Rainer Blasczyk
- Institute for Transfusion Medicine, Hannover Medical School, 30625 Hannover, Germany
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The 5' Untranslated Region of the Major Immediate Early mRNA Is Necessary for Efficient Human Cytomegalovirus Replication. J Virol 2018; 92:JVI.02128-17. [PMID: 29343581 DOI: 10.1128/jvi.02128-17] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2017] [Accepted: 01/15/2018] [Indexed: 02/06/2023] Open
Abstract
The human cytomegalovirus (HCMV) immediate early 1 (IE1) and IE2 proteins are critical regulators of virus replication. Both proteins are needed to efficiently establish lytic infection, and nascent expression of IE1 and IE2 is critical for reactivation from latency. The regulation of IE1 and IE2 protein expression is thus a central event in the outcome of HCMV infection. Transcription of the primary transcript encoding both IE1 and IE2 is well studied, but relatively little is known about the posttranscriptional mechanisms that control IE1 and IE2 protein synthesis. The mRNA 5' untranslated region (5' UTR) plays an important role in regulating mRNA translation. Therefore, to better understand the control of IE1 and IE2 mRNA translation, we examined the role of the shared 5' UTR of the IE1 and IE2 mRNAs (MIE 5' UTR) in regulating translation. In a cell-free system, the MIE 5' UTR repressed translation, as predicted based on its length and sequence composition. However, in transfected cells we found that the MIE 5' UTR increased the expression of a reporter gene and enhanced its association with polysomes, demonstrating that the MIE 5' UTR has a positive role in translation control. We also found that the MIE 5' UTR was necessary for efficient IE1 and IE2 translation during infection. Replacing the MIE 5' UTR with an unstructured sequence of the same length decreased IE1 and IE2 protein expression despite similar levels of IE1 and IE2 mRNA and reduced the association of the IE1 and IE2 mRNAs with polysomes. The wild-type MIE 5'-UTR sequence was also necessary for efficient HCMV replication. Together these data identify the shared 5' UTR of the IE1 and IE2 mRNAs as an important regulator of HCMV lytic replication.IMPORTANCE The HCMV IE1 and IE2 proteins are critical regulators of HCMV replication, both during primary infection and during reactivation from viral latency. Thus, defining factors that regulate IE1 and IE2 expression is important for understanding the molecular events controlling the HCMV replicative cycle. Here we identify a positive role for the MIE 5' UTR in mediating the efficient translation of the IE1 and IE2 mRNAs. This result is an important advance for several reasons. To date, most studies of IE1 and IE2 regulation have focused on defining events that regulate IE1 and IE2 transcription. Our work reveals that in addition to the regulation of transcription, IE1 and IE2 are also regulated at the level of translation. Therefore, this study is important in that it identifies an additional layer of regulation controlling IE1 and IE2 expression and thus HCMV pathogenesis. These translational regulatory events could potentially be targeted by novel antiviral therapeutics that limit IE1 and IE2 mRNA translation and thus inhibit lytic replication or prevent HCMV reactivation.
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Mullen NJ, Price DH. Hydrogen peroxide yields mechanistic insights into human mRNA capping enzyme function. PLoS One 2017; 12:e0186423. [PMID: 29028835 PMCID: PMC5640233 DOI: 10.1371/journal.pone.0186423] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Accepted: 09/29/2017] [Indexed: 12/16/2022] Open
Abstract
Capping of nascent RNA polymerase II (Pol II) transcripts is required for gene expression and the first two steps are catalyzed by separate 5' triphosphatase and guanylyltransferase activities of the human capping enzyme (HCE). The cap is added co-transcriptionally, but how the two activities are coordinated is unclear. Our previous in vitro work has suggested that an unidentified factor modulates the minimum length at which nascent transcripts can be capped. Using the same well-established in vitro system with hydrogen peroxide as a capping inhibitor, we show that this unidentified factor targets the guanylyltransferase activity of HCE. We also uncover the mechanism of HCE inhibition by hydrogen peroxide, and by using mass spectrometry demonstrate that the active site cysteine residue of the HCE triphosphatase domain becomes oxidized. Using recombinant proteins for the two separated HCE domains, we provide evidence that the triphosphatase normally acts on transcripts shorter than can be acted upon by the guanylyltransferase. Our further characterization of the capping reaction dependence on transcript length and its interaction with the unidentified modulator of capping raises the interesting possibility that the capping reaction could be regulated.
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Affiliation(s)
- Nicholas J. Mullen
- Department of Biochemistry, University of Iowa, Iowa City, Iowa, United States of America
| | - David H. Price
- Department of Biochemistry, University of Iowa, Iowa City, Iowa, United States of America
- * E-mail:
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Lin YT, Prendergast J, Grey F. The host ubiquitin-dependent segregase VCP/p97 is required for the onset of human cytomegalovirus replication. PLoS Pathog 2017; 13:e1006329. [PMID: 28494016 PMCID: PMC5426786 DOI: 10.1371/journal.ppat.1006329] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Accepted: 03/31/2017] [Indexed: 11/19/2022] Open
Abstract
The human cytomegalovirus major immediate early proteins IE1 and IE2 are critical drivers of virus replication and are considered pivotal in determining the balance between productive and latent infection. IE1 and IE2 are derived from the same primary transcript by alternative splicing and regulation of their expression likely involves a complex interplay between cellular and viral factors. Here we show that knockdown of the host ubiquitin-dependent segregase VCP/p97, results in loss of IE2 expression, subsequent suppression of early and late gene expression and, ultimately, failure in virus replication. RNAseq analysis showed increased levels of IE1 splicing, with a corresponding decrease in IE2 splicing following VCP knockdown. Global analysis of viral transcription showed the expression of a subset of viral genes is not reduced despite the loss of IE2 expression, including UL112/113. Furthermore, Immunofluorescence studies demonstrated that VCP strongly colocalised with the viral replication compartments in the nucleus. Finally, we show that NMS-873, a small molecule inhibitor of VCP, is a potent HCMV antiviral with potential as a novel host targeting therapeutic for HCMV infection. Viruses are obligate intracellular pathogens, meaning that they are completely dependent on the host cellular machinery to replicate. Identifying which host genes are necessary for virus replication extends our understanding of how viruses replicate, how cells function and provides potential targets for novel antivirals. Here, we show that a cellular factor called valosin containing protein (VCP) is essential for human cytomegalovirus replication. We demonstrate that VCP is required for the expression of an essential virus gene called IE2. Finally we show that a chemical inhibitor of VCP is a potent antiviral against human cytomegalovirus, demonstrating the potential for VCP inhibitors as novel therapeutics against this virus.
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Affiliation(s)
- Yao-Tang Lin
- Division of Infection and Immunity, The Roslin Institute, University of Edinburgh, Easter Bush, Midlothian, United Kingdom
| | - James Prendergast
- Division of Infection and Immunity, The Roslin Institute, University of Edinburgh, Easter Bush, Midlothian, United Kingdom
| | - Finn Grey
- Division of Infection and Immunity, The Roslin Institute, University of Edinburgh, Easter Bush, Midlothian, United Kingdom
- * E-mail:
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Multiple Transcripts Encode Full-Length Human Cytomegalovirus IE1 and IE2 Proteins during Lytic Infection. J Virol 2016; 90:8855-65. [PMID: 27466417 DOI: 10.1128/jvi.00741-16] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Accepted: 07/18/2016] [Indexed: 01/22/2023] Open
Abstract
UNLABELLED Expression of the human cytomegalovirus (HCMV) IE1 and IE2 proteins is critical for the establishment of lytic infection and reactivation from viral latency. Defining the mechanisms controlling IE1 and IE2 expression is therefore important for understanding how HCMV regulates its replicative cycle. Here we identify several novel transcripts encoding full-length IE1 and IE2 proteins during HCMV lytic replication. Two of the alternative major immediate early (MIE) transcripts initiate in the first intron, intron A, of the previously defined MIE transcript, while others extend the 5' untranslated region. Each of the MIE transcripts associates with polyribosomes in infected cells and therefore contributes to IE1 and IE2 protein levels. Surprisingly, deletion of the core promoter region of the major immediate early promoter (MIEP) from a plasmid containing the MIE genomic locus did not completely abrogate IE1 and IE2 expression. Instead, deletion of the MIEP core promoter resulted in increased expression of alternative MIE transcripts, suggesting that the MIEP suppresses the activity of the alternative MIE promoters. While the canonical MIE mRNA was the most abundant transcript at immediate early times, the novel MIE transcripts accumulated to levels equivalent to that of the known MIE transcript later in infection. Using two HCMV recombinants, we found that sequences in intron A of the previously defined MIE transcript are required for efficient IE1 and IE2 expression and viral replication. Together, our results identify new regulatory sequences controlling IE1 and IE2 expression and suggest that multiple transcription units act in concert to regulate IE1 and IE2 expression during lytic infection. IMPORTANCE The HCMV IE1 and IE2 proteins are critical regulators of HCMV replication, both during primary infection and reactivation from viral latency. This study expands our understanding of the sequences controlling IE1 and IE2 expression by defining novel transcriptional units controlling the expression of full-length IE1 and IE2 proteins. Our results suggest that alternative promoters may allow for IE1 and IE2 expression when MIEP activity is limiting, as occurs in latently infected cells.
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Two Polypyrimidine Tracts in Intron 4 of the Major Immediate Early Gene Are Critical for Gene Expression Switching from IE1 to IE2 and for Replication of Human Cytomegalovirus. J Virol 2016; 90:7339-7349. [PMID: 27252533 DOI: 10.1128/jvi.00837-16] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Accepted: 05/25/2016] [Indexed: 02/07/2023] Open
Abstract
UNLABELLED The human cytomegalovirus (HCMV) major immediate early (MIE) gene is essential for viral replication. The most abundant products encoded by the MIE gene include IE1 and IE2. Genes of IE1 and IE2 share the MIE promoter (MIEP), the first 3 exons, and the first 2 introns. IE1 is expressed earlier than IE2 after CMV infection or MIE gene transfection. In this study, we identified 2 polypyrimidine (Py) tracts in intron 4 (between exons 4 and 5) that are responsible for transcriptional switching from IE1 to IE2. The first Py is important and the second one is essential for the splicing and expression of IE2. In searching for the mechanisms of MIE gene switching from IE1 to IE2, we found that the second Py was required for the IE2's fourth intron to bind to a splicing factor such as U2AF65, as determined by an RNA electrophoretic mobility shift assay and a chromatin immunoprecipitation (ChIP) assay, while the first Py enhanced the binding of U2AF65 with the intron. An HCMV BACmid with the second Py mutated failed to produce any virus, while the HCMV with the first Py mutated replicated with a defective phenotype. Furthermore, we designed a small RNA (scRNAPy) that is complementary to the intron RNA covering the two Pys. The scRNAPy interfered with the interaction of U2AF65 with the intron and repressed the IE2 expression. Therefore, our studies implied that IE2 gene splicing might be an anti-CMV target. IMPORTANCE CMV is a ubiquitous herpesvirus and a significant cause of disease and death in the immunocompromised and elderly. Insights into its gene regulation will provide clues in designing anti-CMV strategies. The MIE gene is one of the earliest genes of CMV and is essential for CMV replication. It is known that the MIE gene needs to be spliced to produce more than two proteins; however, how MIE gene splicing is regulated remains elusive. In the present studies, we identified two Pys in intron 4 and found that the first Py is important and the second is required for the splicing and expression of IE2. We further investigated the mechanisms of gene switching from IE1 to IE2 and found that the two Pys are responsible for U2AF65's binding with intron 4. Therefore, the Pys in intron 4 are the cis elements that determine the fate of IE2 splicing. Furthermore, we found that a small RNA that is complementary to intron 4 repressed IE2 expression. Hence, we provide the first piece of evidence for a unique mechanism of MIE gene regulation at the splicing level.
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Even DY, Kedmi A, Basch-Barzilay S, Ideses D, Tikotzki R, Shir-Shapira H, Shefi O, Juven-Gershon T. Engineered Promoters for Potent Transient Overexpression. PLoS One 2016; 11:e0148918. [PMID: 26872062 PMCID: PMC4752495 DOI: 10.1371/journal.pone.0148918] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2015] [Accepted: 01/23/2016] [Indexed: 12/25/2022] Open
Abstract
The core promoter, which is generally defined as the region to which RNA Polymerase II is recruited to initiate transcription, plays a pivotal role in the regulation of gene expression. The core promoter consists of different combinations of several short DNA sequences, termed core promoter elements or motifs, which confer specific functional properties to each promoter. Earlier studies that examined the ability to modulate gene expression levels via the core promoter, led to the design of strong synthetic core promoters, which combine different core elements into a single core promoter. Here, we designed a new core promoter, termed super core promoter 3 (SCP3), which combines four core promoter elements (the TATA box, Inr, MTE and DPE) into a single promoter that drives prolonged and potent gene expression. We analyzed the effect of core promoter architecture on the temporal dynamics of reporter gene expression by engineering EGFP expression vectors that are driven by distinct core promoters. We used live cell imaging and flow cytometric analyses in different human cell lines to demonstrate that SCPs, particularly the novel SCP3, drive unusually strong long-term EGFP expression. Importantly, this is the first demonstration of long-term expression in transiently transfected mammalian cells, indicating that engineered core promoters can provide a novel non-viral strategy for biotechnological as well as gene-therapy-related applications that require potent expression for extended time periods.
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Affiliation(s)
- Dan Y. Even
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, 5290002, Israel
| | - Adi Kedmi
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, 5290002, Israel
| | - Shani Basch-Barzilay
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, 5290002, Israel
| | - Diana Ideses
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, 5290002, Israel
| | - Ravid Tikotzki
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, 5290002, Israel
| | - Hila Shir-Shapira
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, 5290002, Israel
| | - Orit Shefi
- Faculty of Engineering and Bar-Ilan Institute of Nanotechnologies and Advanced Materials, Bar-Ilan University, Ramat-Gan, 5290002, Israel
| | - Tamar Juven-Gershon
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, 5290002, Israel
- * E-mail:
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13
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Liu XF, Jie C, Zhang Z, Yan S, Wang JJ, Wang X, Kurian S, Salomon DR, Abecassis M, Hummel M. Transplant-induced reactivation of murine cytomegalovirus immediate early gene expression is associated with recruitment of NF-κB and AP-1 to the major immediate early promoter. J Gen Virol 2016; 97:941-954. [PMID: 26795571 DOI: 10.1099/jgv.0.000407] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Reactivation of latent human cytomegalovirus is a significant infectious complication of organ transplantation and current therapies target viral replication once reactivation of latent virus has already occurred. The specific molecular pathways that activate viral gene expression in response to transplantation are not well understood. Our studies aim to identify these factors, with the goal of developing novel therapies that prevent transcriptional reactivation in transplant recipients. Murine cytomegalovirus (MCMV) is a valuable model for studying latency and reactivation of CMV in vivo. We previously demonstrated that transplantation of MCMV-latently infected kidneys into allogeneic recipients induces reactivation of immediate early (IE) gene expression and epigenetic reprogramming of the major immediate early promoter (MIEP) within 48 h. We hypothesize that these events are mediated by activation of signalling pathways that lead to binding of transcription factors to the MIEP, including AP-1 and NF-κB. Here we show that transplantation induces rapid activation of several members of the AP-1 and NF-κB transcription factor family and we demonstrate that canonical NF-κB (p65/p50), the junD component of AP-1, and nucleosome remodelling complexes are recruited to the MIEP following transplantation. Proteomic analysis of recipient plasma and transcriptome analysis of kidney RNA identified five extracellular ligands, including TNF, IL-1β, IL-18, CD40L and IL-6, and three intracellular signalling pathways associated with reactivation of IE gene expression. Identification of the factors that mediate activation of these signalling pathways may eventually lead to new therapies to prevent reactivation of CMV and its sequelae.
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Affiliation(s)
- Xue-Feng Liu
- Comprehensive Transplant Center, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Chunfa Jie
- Comprehensive Transplant Center, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Zheng Zhang
- Comprehensive Transplant Center, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Shixian Yan
- Comprehensive Transplant Center, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Jiao-Jing Wang
- Comprehensive Transplant Center, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Xueqiong Wang
- Comprehensive Transplant Center, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Sunil Kurian
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, LaJolla, CA, USA
| | - Daniel R Salomon
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, LaJolla, CA, USA
| | - Michael Abecassis
- Department of Microbiology and Immunology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
- Comprehensive Transplant Center, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Mary Hummel
- Department of Microbiology and Immunology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
- Comprehensive Transplant Center, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
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Scherer M, Wagenknecht N, Reuter N, Stamminger T. Silencing of Human Cytomegalovirus Gene Expression Mediated by Components of PML Nuclear Bodies. EPIGENETICS - A DIFFERENT WAY OF LOOKING AT GENETICS 2016. [DOI: 10.1007/978-3-319-27186-6_9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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15
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Wagenknecht N, Reuter N, Scherer M, Reichel A, Müller R, Stamminger T. Contribution of the Major ND10 Proteins PML, hDaxx and Sp100 to the Regulation of Human Cytomegalovirus Latency and Lytic Replication in the Monocytic Cell Line THP-1. Viruses 2015; 7:2884-907. [PMID: 26057166 PMCID: PMC4488718 DOI: 10.3390/v7062751] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Accepted: 06/01/2015] [Indexed: 01/16/2023] Open
Abstract
Promyelocytic leukemia nuclear bodies, also termed nuclear domain 10 (ND10), have emerged as nuclear protein accumulations mediating an intrinsic cellular defense against viral infections via chromatin-based mechanisms, however, their contribution to the control of herpesviral latency is still controversial. In this study, we utilized the monocytic cell line THP-1 as an in vitro latency model for human cytomegalovirus infection (HCMV). Characterization of THP-1 cells by immunofluorescence andWestern blot analysis confirmed the expression of all major ND10 components. THP-1 cells with a stable, individual knockdown of PML, hDaxx or Sp100 were generated. Importantly, depletion of the major ND10 proteins did not prevent the terminal cellular differentiation of THP-1 monocytes. After construction of a recombinant, endotheliotropic human cytomegalovirus expressing IE2-EYFP, we investigated whether the depletion of ND10 proteins affects the onset of viral IE gene expression. While after infection of differentiated, THP-1-derived macrophages as well as during differentiation-induced reactivation from latency an increase in the number of IE-expressing cells was readily detectable in the absence of the major ND10 proteins, no effect was observed in non-differentiated monocytes. We conclude that PML, hDaxx and Sp100 primarily act as cellular restriction factors during lytic HCMV replication and during the dynamic process of reactivation but do not serve as key determinants for the establishment of HCMV latency.
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Affiliation(s)
- Nadine Wagenknecht
- Institute of Clinical and Molecular Virology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Schlossgarten 4, 91054 Erlangen, Germany.
| | - Nina Reuter
- Institute of Clinical and Molecular Virology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Schlossgarten 4, 91054 Erlangen, Germany.
| | - Myriam Scherer
- Institute of Clinical and Molecular Virology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Schlossgarten 4, 91054 Erlangen, Germany.
| | - Anna Reichel
- Institute of Clinical and Molecular Virology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Schlossgarten 4, 91054 Erlangen, Germany.
| | - Regina Müller
- Institute of Clinical and Molecular Virology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Schlossgarten 4, 91054 Erlangen, Germany.
| | - Thomas Stamminger
- Institute of Clinical and Molecular Virology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Schlossgarten 4, 91054 Erlangen, Germany.
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16
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Dutta N, Lashmit P, Yuan J, Meier J, Stinski MF. The human cytomegalovirus UL133-138 gene locus attenuates the lytic viral cycle in fibroblasts. PLoS One 2015; 10:e0120946. [PMID: 25799165 PMCID: PMC4370700 DOI: 10.1371/journal.pone.0120946] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2013] [Accepted: 02/12/2015] [Indexed: 12/22/2022] Open
Abstract
The genomes of HCMV clinical strains (e.g. FIX, TR, PH, etc) contain a 15 kb region that encodes 20 putative ORFs. The region, termed ULb’, is lost after serial passage of virus in human foreskin fibroblast (HFF) cell culture. Compared to clinical strains, laboratory strains replicate faster and to higher titers of infectious virus. We made recombinant viruses with 22, 14, or 7 ORFs deleted from the ULb’ region using FIX and TR as model clinical strains. We also introduced a stop codon into single ORFs between UL133 and UL138 to prevent protein expression. All deletions within ULb’ and all stop codon mutants within the UL133 to UL138 region increased to varying degrees, viral major immediate early RNA and protein, DNA, and cell-free infectious virus compared to the wild type viruses. The wild type viral proteins slowed down the viral replication process along with cell-free infectious virus release from human fibroblast cells.
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Affiliation(s)
- Nirmal Dutta
- Department of Internal Medicine, University of Iowa, Iowa City, United States of America
| | - Philip Lashmit
- Center for Biocatalysis and Bioprocessing, University of Iowa, Iowa City, United States of America
| | - Jinxiang Yuan
- Department of Internal Medicine, University of Iowa, Iowa City, United States of America
| | - Jeffery Meier
- Department of Internal Medicine, University of Iowa, Iowa City, United States of America
- Iowa Veterans Affairs Healthcare System, Iowa City, United States of America
| | - Mark F. Stinski
- Department of Microbiology, University of Iowa, Iowa City, United States of America
- * E-mail:
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17
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CTCF binding to the first intron of the major immediate early (MIE) gene of human cytomegalovirus (HCMV) negatively regulates MIE gene expression and HCMV replication. J Virol 2014; 88:7389-401. [PMID: 24741094 DOI: 10.1128/jvi.00845-14] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
UNLABELLED Human cytomegalovirus (HCMV) gene expression during infection is highly regulated, with sequential expression of immediate-early (IE), early (E), and late (L) gene transcripts. To explore the potential role of chromatin regulatory factors that may regulate HCMV gene expression and DNA replication, we investigated the interaction of HCMV with the cellular chromatin-organizing factor CTCF. Here, we show that HCMV-infected cells produce higher levels of CTCF mRNA and protein at early stages of infection. We also show that CTCF depletion by short hairpin RNA results in an increase in major IE (MIE) and E gene expression and an about 50-fold increase in HCMV particle production. We identified a DNA sequence (TTAACGGTGGAGGGCAGTGT) in the first intron (intron A) of the MIE gene that interacts directly with CTCF. Deletion of this CTCF-binding site led to an increase in MIE gene expression in both transient-transfection and infection assays. Deletion of the CTCF-binding site in the HCMV bacterial artificial chromosome plasmid genome resulted in an about 10-fold increase in the rate of viral replication relative to either wild-type or revertant HCMV. The CTCF-binding site deletion had no detectable effect on MIE gene-splicing regulation, nor did CTCF knockdown or overexpression of CTCF alter the ratio of IE1 to IE2. Therefore, CTCF binds to DNA within the MIE gene at the position of the first intron to affect RNA polymerase II function during the early stages of viral transcription. Finally, the CTCF-binding sequence in CMV is evolutionarily conserved, as a similar sequence in murine CMV (MCMV) intron A was found to interact with CTCF and similarly function in the repression of MCMV MIE gene expression mediated by CTCF. IMPORTANCE Our findings that CTCF binds to intron A of the cytomegalovirus (CMV) major immediate-early (MIE) gene and functions to repress MIE gene expression and viral replication are highly significant. For the first time, a chromatin-organizing factor, CTCF, has been found to facilitate human CMV gene expression, which affects viral replication. We also identified a CTCF-binding motif in the first intron (also called intron A) that directly binds to CTCF and is required for CTCF to repress MIE gene expression. Finally, we show that the CTCF-binding motif is conserved in CMV because a similar DNA sequence was found in murine CMV (MCMV) that is required for CTCF to bind to MCMV MIE gene to repress MCMV MIE gene expression.
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18
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Scherer M, Stamminger T. The human cytomegalovirus IE1 protein: past and present developments. Future Virol 2014. [DOI: 10.2217/fvl.14.20] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
ABSTRACT: Human cytomegalovirus (HCMV), a member of the β-herpesvirus subfamily, is an important pathogen that infects the majority of the human population. The evolutionary success of HCMV largely depends on its ability to evade host defense systems and establish a lifelong persistence after primary infection. In fact, HCMV has dedicated a considerable part of its gene products to manipulate or disable immune effector processes. This review focuses on the major immediate–early protein IE1 – a multifunctional key regulator that has the capacity to counteract the first host defense activities. We summarize the known structural and mechanistic features by which IE1 modulates innate immune mechanisms as well as other cellular processes, and discuss how the individual functions of IE1 contribute to the success of a lytic HCMV infection.
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Affiliation(s)
- Myriam Scherer
- Institute for Clinical & Molecular Virology, University of Erlangen-Nuremberg, Schlossgarten 4, 91054 Erlangen, Germany
| | - Thomas Stamminger
- Institute for Clinical & Molecular Virology, University of Erlangen-Nuremberg, Schlossgarten 4, 91054 Erlangen, Germany
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19
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Lee YL, Liu CE, Cho WL, Kuo CL, Cheng WL, Huang CS, Liu CS. Presence of cytomegalovirus DNA in leucocytes is associated with increased oxidative stress and subclinical atherosclerosis in healthy adults. Biomarkers 2014; 19:109-13. [PMID: 24446591 DOI: 10.3109/1354750x.2013.877967] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
OBJECTIVE Investigate the latent cytomegalovirus (CMV) infection as a biomarker of oxidative stress and atherosclerosis. METHODS Latent CMV infection was diagnosed in healthy individuals with PCR-evidence of CMV DNA in peripheral leucocytes. Oxidative stress and atherosclerosis were measured by mitochondrial DNA oxidative damage index (mtDNA(ΔCT)) and intima media thickness (IMT). RESULTS The CMV DNA positive subjects had a higher mean mtDNA(ΔCT) and greater IMT than subjects in the control group. CONCLUSIONS Presence of CMV DNA in leucocytes, as a marker of latent CMV infection, was associated with increased levels of oxidative stress and subclinical atherosclerosis in healthy adults.
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Affiliation(s)
- Yu-Lin Lee
- Department of Internal Medicine, Division of Infectious Diseases, Changhua Christian Hospital , Changhua , Taiwan
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20
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Abstract
The history of the molecular biology of cytomegaloviruses from the purification of the virus and the viral DNA to the cloning and expression of the viral genes is reviewed. A key genetic element of cytomegalovirus (the CMV promoter) contributed to our understanding of eukaryotic cell molecular biology and to the development of lifesaving therapeutic proteins. The study of the molecular biology of cytomegaloviruses also contributed to the development of antivirals to control the viral infection.
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Affiliation(s)
- Mark F Stinski
- Department of Microbiology, Carver College of Medicine, University of Iowa, 3-701 BSB, 51 Newton Rd., Iowa City, IA, 52242, USA,
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21
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Identification of cellular proteins that interact with human cytomegalovirus immediate-early protein 1 by protein array assay. Viruses 2013; 6:89-105. [PMID: 24385082 PMCID: PMC3917433 DOI: 10.3390/v6010089] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2013] [Revised: 12/10/2013] [Accepted: 12/20/2013] [Indexed: 12/13/2022] Open
Abstract
Human cytomegalovirus (HCMV) gene expression during infection is characterized as a sequential process including immediate-early (IE), early (E), and late (L)-stage gene expression. The most abundantly expressed gene at the IE stage of infection is the major IE (MIE) gene that produces IE1 and IE2. IE1 has been the focus of study because it is an important protein, not only for viral gene expression but also for viral replication. It is believed that IE1 plays important roles in viral gene regulation by interacting with cellular proteins. In the current study, we performed protein array assays and identified 83 cellular proteins that interact with IE1. Among them, seven are RNA-binding proteins that are important in RNA processing; more than half are nuclear proteins that are involved in gene regulations. Tumorigenesis-related proteins are also found to interact with IE1, implying that the role of IE1 in tumorigenesis might need to be reevaluated. Unexpectedly, cytoplasmic proteins, such as Golgi autoantigen and GGA1 (both related to the Golgi trafficking protein), are also found to be associated with IE1. We also employed a coimmunoprecipitation assay to test the interactions of IE1 and some of the proteins identified in the protein array assays and confirmed that the results from the protein array assays are reliable. Many of the proteins identified by the protein array assay have not been previously reported. Therefore, the functions of the IE1-protein interactions need to be further explored in the future.
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22
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Human cytomegalovirus infection of langerhans-type dendritic cells does not require the presence of the gH/gL/UL128-131A complex and is blocked after nuclear deposition of viral genomes in immature cells. J Virol 2013; 88:403-16. [PMID: 24155395 DOI: 10.1128/jvi.03062-13] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Human cytomegalovirus (CMV) enters its host via the oral and genital mucosae. Langerhans-type dendritic cells (LC) are the most abundant innate immune cells at these sites, where they constitute a first line of defense against a variety of pathogens. We previously showed that immature LC (iLC) are remarkably resistant to CMV infection, while mature LC (mLC) are more permissive, particularly when exposed to clinical-strain-like strains of CMV, which display a pentameric complex consisting of the viral glycoproteins gH, gL, UL128, UL130, and UL131A on their envelope. This complex was recently shown to be required for the infection of immature monocyte-derived dendritic cells. We thus sought to establish if the presence of this complex is also necessary for virion penetration of LC and if defects in entry might be the source of iLC resistance to CMV. Here we report that the efficiency of LC infection is reduced, but not completely abolished, in the absence of the pentameric complex. While virion penetration and nuclear deposition of viral genomes are not impaired in iLC, the transcription of the viral immediate early genes UL122 and UL123 and of the delayed early gene UL50 is substantially lower than that in mLC. Together, these data show that the UL128, UL130, and UL131A proteins are dispensable for CMV entry into LC and that progression of the viral cycle in iLC is restricted at the step of viral gene expression.
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23
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Gatherer D, Seirafian S, Cunningham C, Holton M, Dargan DJ, Baluchova K, Hector RD, Galbraith J, Herzyk P, Wilkinson GWG, Davison AJ. High-resolution human cytomegalovirus transcriptome. Proc Natl Acad Sci U S A 2011; 108:19755-60. [PMID: 22109557 PMCID: PMC3241806 DOI: 10.1073/pnas.1115861108] [Citation(s) in RCA: 178] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Deep sequencing was used to bring high resolution to the human cytomegalovirus (HCMV) transcriptome at the stage when infectious virion production is under way, and major findings were confirmed by extensive experimentation using conventional techniques. The majority (65.1%) of polyadenylated viral RNA transcription is committed to producing four noncoding transcripts (RNA2.7, RNA1.2, RNA4.9, and RNA5.0) that do not substantially overlap designated protein-coding regions. Additional noncoding RNAs that are transcribed antisense to protein-coding regions map throughout the genome and account for 8.7% of transcription from these regions. RNA splicing is more common than recognized previously, which was evidenced by the identification of 229 potential donor and 132 acceptor sites, and it affects 58 protein-coding genes. The great majority (94) of 96 splice junctions most abundantly represented in the deep-sequencing data was confirmed by RT-PCR or RACE or supported by involvement in alternative splicing. Alternative splicing is frequent and particularly evident in four genes (RL8A, UL74A, UL124, and UL150A) that are transcribed by splicing from any one of many upstream exons. The analysis also resulted in the annotation of four previously unrecognized protein-coding regions (RL8A, RL9A, UL150A, and US33A), and expression of the UL150A protein was shown in the context of HCMV infection. The overall conclusion, that HCMV transcription is complex and multifaceted, has implications for the potential sophistication of virus functionality during infection. The study also illustrates the key contribution that deep sequencing can make to the genomics of nuclear DNA viruses.
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Affiliation(s)
- Derek Gatherer
- Medical Research Council–University of Glasgow Centre for Virus Research, Glasgow G11 5JR, United Kingdom
| | - Sepehr Seirafian
- School of Medicine, Cardiff University, Cardiff CF14 4XN, United Kingdom; and
| | - Charles Cunningham
- Medical Research Council–University of Glasgow Centre for Virus Research, Glasgow G11 5JR, United Kingdom
| | - Mary Holton
- Medical Research Council–University of Glasgow Centre for Virus Research, Glasgow G11 5JR, United Kingdom
| | - Derrick J. Dargan
- Medical Research Council–University of Glasgow Centre for Virus Research, Glasgow G11 5JR, United Kingdom
| | - Katarina Baluchova
- Medical Research Council–University of Glasgow Centre for Virus Research, Glasgow G11 5JR, United Kingdom
| | - Ralph D. Hector
- Medical Research Council–University of Glasgow Centre for Virus Research, Glasgow G11 5JR, United Kingdom
| | - Julie Galbraith
- Sir Henry Wellcome Functional Genomics Facility, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - Pawel Herzyk
- Sir Henry Wellcome Functional Genomics Facility, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | | | - Andrew J. Davison
- Medical Research Council–University of Glasgow Centre for Virus Research, Glasgow G11 5JR, United Kingdom
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24
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Hancks DC, Goodier JL, Mandal PK, Cheung LE, Kazazian HH. Retrotransposition of marked SVA elements by human L1s in cultured cells. Hum Mol Genet 2011; 20:3386-400. [PMID: 21636526 DOI: 10.1093/hmg/ddr245] [Citation(s) in RCA: 150] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Human retrotransposons generate structural variation and genomic diversity through ongoing retrotransposition and non-allelic homologous recombination. Cell culture retrotransposition assays have provided great insight into the genomic impact of retrotransposons, in particular, LINE-1(L1) and Alu elements; however, no such assay exists for the youngest active human retrotransposon, SINE-VNTR-Alu (SVA). Here we report the development of an SVA cell culture retrotransposition assay. We marked several SVAs with either neomycin or EGFP retrotransposition indicator cassettes. Engineered SVAs retrotranspose using L1 proteins supplemented in trans in multiple cell lines, including U2OS osteosarcoma cells where SVA retrotransposition is equal to that of an engineered L1. Engineered SVAs retrotranspose at 1-54 times the frequency of a marked pseudogene in HeLa HA cells. Furthermore, our data suggest a variable requirement for L1 ORF1p for SVA retrotransposition. Recovered engineered SVA insertions display all the hallmarks of LINE-1 retrotransposition and some contain 5' and 3' transductions, which are common for genomic SVAs. Of particular interest is the fact that four out of five insertions recovered from one SVA are full-length, with the 5' end of these insertions beginning within 5 nt of the CMV promoter transcriptional start site. This assay demonstrates that SVA elements are indeed mobilized in trans by L1. Previously intractable questions regarding SVA biology can now be addressed.
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Affiliation(s)
- Dustin C Hancks
- Cell and Molecular Biology Graduate Group, The University of Pennsylvania School of Medicine, Philadelphia, PA, USA
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25
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Aihara Y, Fujiwara N, Yamazaki T, Kambe T, Nagao M, Hirose Y, Masuda S. Enhancing recombinant protein production in human cell lines with a constitutive transport element and mRNA export proteins. J Biotechnol 2011; 153:86-91. [PMID: 21473891 DOI: 10.1016/j.jbiotec.2011.03.024] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2010] [Revised: 03/05/2011] [Accepted: 03/29/2011] [Indexed: 11/16/2022]
Abstract
Recent research into mRNA maturation processes in the nucleus has identified a number of proteins involved in mRNA transcription, capping, splicing, end processing and export. Among them, the Tap-p15 heterodimer acts as an mRNA export receptor. Tap-p15 is recruited onto fully processed mRNA in the nucleus, which is ready for export to the cytoplasm, through associating with Aly or SR proteins on mRNA, or by directly associating with a constitutive transport element (CTE), an RNA element derived from type D retroviruses. mRNA containing a CTE is exported to the cytoplasm by directly associating with Tap-p15, even in the absence of Tap-recruiting proteins such as Aly or SR proteins on the mRNA. Here, we showed that the use of a CTE enhanced the expression of recombinant protein in human cell lines. The co-expression of reporter proteins and Tap-p15 also enhanced recombinant protein expression. Moreover, the use of a CTE and Tap-p15 synergistically further enhanced the recombinant protein expression. In addition to Tap-p15, several Tap-p15-recruiting proteins, including Aly and SR proteins, enhanced recombinant protein expression, albeit independently of the CTE. The incorporation of a CTE and Tap-p15-recruiting proteins into protein expression system is useful to increase recombinant protein yield in human cells.
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Affiliation(s)
- Yuki Aihara
- Division of Integrated Life Science, Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan
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26
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Alternative splicing of the human cytomegalovirus major immediate-early genes affects infectious-virus replication and control of cellular cyclin-dependent kinase. J Virol 2010; 85:804-17. [PMID: 21068259 DOI: 10.1128/jvi.01173-10] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The major immediate-early (MIE) gene locus of human cytomegalovirus (HCMV) is the master switch that determines the outcomes of both lytic and latent infections. Here, we provide evidence that alteration in the splicing of HCMV (Towne strain) MIE genes affects infectious-virus replication, movement through the cell cycle, and cyclin-dependent kinase activity. Mutation of a conserved 24-nucleotide region in MIE exon 4 increased the abundance of IE1-p38 mRNA and decreased the abundance of IE1-p72 and IE2-p86 mRNAs. An increase in IE1-p38 protein was accompanied by a slight decrease in IE1-p72 protein and a significant decrease in IE2-p86 protein. The mutant virus had growth defects, which could not be complemented by wild-type IE1-p72 protein in trans. The phenotype of the mutant virus could not be explained by an increase in IE1-p38 protein, but prevention of the alternate splice returned the recombinant virus to the wild-type phenotype. The lower levels of IE1-p72 and IE2-p86 proteins correlated with a delay in early and late viral gene expression and movement into the S phase of the cell cycle. Mutant virus-infected cells had significantly higher levels of cdk-1 expression and enzymatic activity than cells infected with wild-type virus. The mutant virus induced a round-cell phenotype that accumulated in the G(2)/M compartment of the cell cycle with condensation and fragmentation of the chromatin. An inhibitor of viral DNA synthesis increased the round-cell phenotype. The round cells were characteristic of an abortive viral infection.
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27
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Importance of covalent and noncovalent SUMO interactions with the major human cytomegalovirus transactivator IE2p86 for viral infection. J Virol 2009; 83:12881-94. [PMID: 19812159 DOI: 10.1128/jvi.01525-09] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The major transactivator protein IE2p86 of human cytomegalovirus (HCMV) has previously been shown to undergo posttranslational modification by the covalent attachment of SUMO proteins, termed SUMOylation, which occurs at two lysine residues located at amino acid positions 175 and 180. Mutation of the acceptor lysines resulted in the abrogation of IE2p86 SUMOylation in mammalian cells and a strong reduction of IE2p86-mediated transactivation. In this paper, we identify an additional SUMO interaction motif (SIM) within IE2p86, which mediates noncovalent binding to SUMO, as shown by yeast two-hybrid analyses. Transient-expression experiments revealed that an IE2p86 SIM mutant exhibited significantly reduced SUMOylation, strongly suggesting that noncovalent SUMO interactions affect the efficacy of covalent SUMO coupling. In order to define the relevance of IE2p86 SUMO interactions for viral replication, recombinant viruses originating from two different HCMV strains (AD169 and VR1814) were generated. Analysis of viruses expressing SUMOylation-negative IE2p86 revealed strongly impaired replication due to reduced viral DNA and protein accumulation, as well as diminished initiation of immediate-early gene expression. The additional introduction of the SIM mutation into the viral genome did not further compromise viral replication but resulted in altered expression of viral proteins at late times postinfection. In summary, this paper clearly shows that IE2p86 SUMOylation is necessary for efficient replication of the HCMV laboratory strain AD169 and the clinical isolate VR1814 and thus for the in vivo function of this viral transcription factor.
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28
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Koh K, Lee K, Ahn JH, Kim S. Human cytomegalovirus infection downregulates the expression of glial fibrillary acidic protein in human glioblastoma U373MG cells: identification of viral genes and protein domains involved. J Gen Virol 2009; 90:954-962. [PMID: 19264642 DOI: 10.1099/vir.0.006486-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Human cytomegalovirus (HCMV) has tropism for glial cells, among many other cell types. It was reported previously that the stable expression of HCMV immediate-early protein 1 (IE1) could dramatically reduce the RNA level of glial fibrillary acidic protein (GFAP), an astroglial cell-specific intermediate filament protein, which is progressively lost with an increase in glioma malignancy. To understand this phenomenon in the context of virus infection, a human glioblastoma cell line, U373MG, was infected with HCMV (strain AD169 or Towne). The RNA level of GFAP was reduced by more than 10-fold at an m.o.i. of 3 at 48 h post-infection, whilst virus treated with neutralizing antibody C23 or with UV light had a much-reduced effect. Treatment of infected cells with ganciclovir did not prevent HCMV-mediated downregulation of GFAP. Although the expression of GFAP RNA is downregulated in IE1-expressing cells, a mutant HCMV strain lacking IE1 still suppressed GFAP, indicating that other IE proteins may be involved. IE2 is also proposed to be involved in GFAP downregulation, as an adenoviral vector expressing IE2 could also reduce the RNA level of GFAP. Data from the mutational analysis indicated that HCMV infection might affect the expression of this structural protein significantly, primarily through the C-terminal acidic region of the IE1 protein.
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Affiliation(s)
- Kyungmi Koh
- School of Biological Sciences, Seoul National University, Seoul 151-747, Republic of Korea
| | - Karim Lee
- School of Biological Sciences, Seoul National University, Seoul 151-747, Republic of Korea
| | - Jin-Hyun Ahn
- Department of Molecular Cell Biology, Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine, Suwon, Kyonggido 440-746, Republic of Korea
| | - Sunyoung Kim
- School of Biological Sciences, Seoul National University, Seoul 151-747, Republic of Korea
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Roles of polypyrimidine tract binding proteins in major immediate-early gene expression and viral replication of human cytomegalovirus. J Virol 2009; 83:2839-50. [PMID: 19144709 DOI: 10.1128/jvi.02407-08] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Human cytomegalovirus (HCMV), a member of the beta subgroup of the family Herpesviridae, causes serious health problems worldwide. HCMV gene expression in host cells is a well-defined sequential process: immediate-early (IE) gene expression, early-gene expression, DNA replication, and late-gene expression. The most abundant IE gene, major IE (MIE) gene pre-mRNA, needs to be spliced before being exported to the cytoplasm for translation. In this study, the regulation of MIE gene splicing was investigated; in so doing, we found that polypyrimidine tract binding proteins (PTBs) strongly repressed MIE gene production in cotransfection assays. In addition, we discovered that the repressive effects of PTB could be rescued by splicing factor U2AF. Taken together, the results suggest that PTBs inhibit MIE gene splicing by competing with U2AF65 for binding to the polypyrimidine tract in pre-mRNA. In intron deletion mutation assays and RNA detection experiments (reverse transcription [RT]-PCR and real-time RT-PCR), we further observed that PTBs target all the introns of the MIE gene, especially intron 2, and affect gene splicing, which was reflected in the variation in the ratio of pre-mRNA to mRNA. Using transfection assays, we demonstrated that PTB knockdown cells induce a higher degree of MIE gene splicing/expression. Consistently, HCMV can produce more viral proteins and viral particles in PTB knockdown cells after infection. We conclude that PTB inhibits HCMV replication by interfering with MIE gene splicing through competition with U2AF for binding to the polypyrimidine tract in MIE gene introns.
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30
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Internal deletions of IE2 86 and loss of the late IE2 60 and IE2 40 proteins encoded by human cytomegalovirus affect the levels of UL84 protein but not the amount of UL84 mRNA or the loading and distribution of the mRNA on polysomes. J Virol 2008; 82:11383-97. [PMID: 18787008 DOI: 10.1128/jvi.01293-08] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The major immediate-early (IE) region of human cytomegalovirus encodes two IE proteins, IE1 72 and IE2 86, that are translated from alternatively spliced transcripts that differ in their 3' ends. Two other proteins that correspond to the C-terminal region of IE2 86, IE2 60 and IE2 40, are expressed at late times. In this study, we used IE2 mutant viruses to examine the mechanism by which IE2 86, IE2 60, and IE2 40 affect the expression of a viral DNA replication factor, UL84. Deletion of amino acids (aa) 136 to 290 of IE2 86 results in a significant decrease in UL84 protein during the infection. This loss of UL84 is both proteasome and calpain independent, and the stability of the protein in the context of infection with the mutant remains unaffected. The RNA for UL84 is expressed to normal levels in the mutant virus-infected cells, as are the RNAs for two other proteins encoded by this region, UL85 and UL86. Moreover, nuclear-to-cytoplasmic transport and the distribution of the UL84 mRNA on polysomes are unaffected. A region between aa 290 and 369 of IE2 86 contributes to the UL84-IE2 86 interaction in vivo and in vitro. IE2 86, IE2 60, and IE2 40 are each able to interact with UL84 in the mutant-infected cells, suggesting that these interactions may be important for the roles of UL84 and the IE2 proteins. Thus, these data have defined the contribution of IE2 86, IE2 60, and IE2 40 to the efficient expression of UL84 throughout the infection.
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31
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Grey F, Nelson J. Identification and function of human cytomegalovirus microRNAs. J Clin Virol 2008; 41:186-91. [PMID: 18243786 DOI: 10.1016/j.jcv.2007.11.024] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2007] [Revised: 11/13/2007] [Accepted: 11/28/2007] [Indexed: 02/06/2023]
Abstract
microRNAs are an extensive class of non-coding genes that regulate gene expression through post-transcriptional repression. These small RNAs are evolutionarily conserved and are likely to be a basic mechanism of gene regulation present within most eukaryotic organisms. Over 100 viral miRNAs have been identified to date through a combination of bioinformatics and cloning studies. In this review we discuss the use of bioinformatics for the identification of HCMV miRNAs and also for the discovery of potential target transcripts. Such studies will enable us to define the functional role of viral miRNAs and gain a better understanding of viral gene regulation.
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Affiliation(s)
- Finn Grey
- Vaccine & Gene Therapy Institute, 505 NW 185th Avenue, Oregon Health Sciences University, Portland, OR 97006, USA.
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32
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A human cytomegalovirus-encoded microRNA regulates expression of multiple viral genes involved in replication. PLoS Pathog 2008; 3:e163. [PMID: 17983268 PMCID: PMC2048532 DOI: 10.1371/journal.ppat.0030163] [Citation(s) in RCA: 220] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2007] [Accepted: 09/20/2007] [Indexed: 12/13/2022] Open
Abstract
Although multiple studies have documented the expression of over 70 novel virus-encoded microRNAs (miRNAs), the targets and functions of most of these regulatory RNA species are unknown. In this study a comparative bioinformatics approach was employed to identify potential human cytomegalovirus (HCMV) mRNA targets of the virus-encoded miRNA miR-UL112-1. Bioinformatics analysis of the known HCMV mRNA 3' untranslated regions (UTRs) revealed 14 potential viral transcripts that were predicted to contain functional target sites for miR-UL112-1. The potential target sites were screened using luciferase reporters that contain the HCMV 3'UTRs in co-transfection assays with miR-UL112-1. Three of the 14 HCMV miRNA targets were validated, including the major immediate early gene encoding IE72 (UL123, IE1), UL112/113, and UL120/121. Further analysis of IE72 regulation by miR-UL112-1 with clones encoding the complete major immediate early region revealed that the IE72 3'UTR target site is necessary and sufficient to direct miR-UL112-1-specific inhibition of expression in transfected cells. In addition, miR-UL112-1 regulation is mediated through translational inhibition rather than RNA degradation. Premature expression of miR-UL112-1 during HCMV infection resulted in a significant decrease in genomic viral DNA levels, suggesting a functional role for miR-UL112-1 in regulating the expression of genes involved in viral replication. This study demonstrates the ability of a viral miRNA to regulate multiple viral genes.
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33
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Abstract
The IE86 protein of human cytomegalovirus (HCMV) is unique among viral and cellular proteins because it negatively autoregulates its own expression, activates the viral early and late promoters, and both activates and inhibits cellular promoters. It promotes cell cycle progression from Go/G1 to G1/S and arrests cell cycle progression at the G1/S interface or at G2/M. The IE86 protein is essential because it creates a cellular environment favorable for viral replication. The multiple functions of the IE86 protein during the replication of HCMV are reviewed.
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Abstract
Human cytomegalovirus (HCMV) contains a large and complex E-type genome. There are both clinical isolates of the virus that have been passaged minimally in fibroblasts and so-called laboratory strains that have been extensively passaged and adapted to growth in fibroblasts. The genomes of laboratory strains have undergone rearrangements. To date, the genomes of five clinical isolates have been sequenced. We have re-evaluated the coding content of clinical isolates by identifying the set of open reading frames (ORFs) that are conserved in all five sequenced clinical isolates. We have further determined which of these ORFs are present in the chimpanzee cytomegalovirus (CCMV) genome. A total of 173 ORFs are present in all HCMV genomes and the CCMV genome, and we conclude that these ORFs are very likely to be functional. An additional 59 ORFs are present in the genomes of all five HCMV isolates, but not in CCMV. We have discounted 26 of this latter set of ORFs, because they reside in regions of the genome unlikely to encode functional ORFs. The remaining 33 ORFs are potentially functional ORFs that are specific to HCMV.
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Affiliation(s)
- E Murphy
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544-1014, USA
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35
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Sourvinos G, Tavalai N, Berndt A, Spandidos DA, Stamminger T. Recruitment of human cytomegalovirus immediate-early 2 protein onto parental viral genomes in association with ND10 in live-infected cells. J Virol 2007; 81:10123-36. [PMID: 17626080 PMCID: PMC2045433 DOI: 10.1128/jvi.01009-07] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2007] [Accepted: 07/03/2007] [Indexed: 01/20/2023] Open
Abstract
The human cytomegalovirus (HCMV) immediate-early 2 (IE2) transactivator has previously been shown to form intranuclear, dot-like accumulations in association with subnuclear structures known as promyelocytic leukemia protein (PML) nuclear bodies or ND10. We recently observed that IE2 can form dot-like structures even after infection of PML knockdown cells, which lack genuine ND10. To further analyze the determinants of IE2 subnuclear localization, a recombinant HCMV expressing IE2 fused to the enhanced green fluorescent protein was constructed. We infected primary human fibroblasts expressing Sp100 fused to the autofluorescent protein mCherry while performing live-cell imaging experiments. These experiments revealed a very dynamic association of IE2 dots with ND10 structures during the first hours postinfection: juxtaposed structures rapidly fused to precise co-localizations, followed by segregation, and finally, the dispersal of ND10 accumulations. Furthermore, by infecting PML knockdown cells we determined that the number of IE2 accumulations was dependent on the multiplicity of infection. Since time-lapse microscopy in live-infected cells revealed that IE2 foci developed into viral replication compartments, we hypothesized that viral DNA could act as a determinant of IE2 accumulations. Direct evidence that IE2 molecules are associated with viral DNA early after HCMV infection was obtained using fluorescence in situ hybridization. Finally, a DNA-binding-deficient IE2 mutant could no longer be recruited into viral replication centers, suggesting that the association of IE2 with viral DNA is mediated by a direct DNA contact. Thus, we identified viral DNA as an important determinant of IE2 subnuclear localization, which suggests that the formation of a virus-induced nucleoprotein complex and its spatial organization is likely to be critical at the early stages of a lytic infection.
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Affiliation(s)
- George Sourvinos
- Institut für Klinische und Molekulare Virologie, University Hospital Erlangen, Schlossgarten 4, 91054 Erlangen, Germany
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36
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Zhang G, Raghavan B, Kotur M, Cheatham J, Sedmak D, Cook C, Waldman J, Trgovcich J. Antisense transcription in the human cytomegalovirus transcriptome. J Virol 2007; 81:11267-81. [PMID: 17686857 PMCID: PMC2045512 DOI: 10.1128/jvi.00007-07] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Human cytomegalovirus (HCMV) infections are prevalent in human populations and can cause serious diseases, especially in those with compromised or immature immune systems. The HCMV genome of 230 kb is among the largest of the herpesvirus genomes. Although the entire sequence of the laboratory-adapted AD169 strain of HCMV has been available for 18 years, the precise number of viral genes is still in question. We undertook an analysis of the HCMV transcriptome as an approach to enumerate and analyze the gene products of HCMV. Transcripts of HCMV-infected fibroblasts were isolated at different times after infection and used to generate cDNA libraries representing different temporal classes of viral genes. cDNA clones harboring viral sequences were selected and subjected to sequence analysis. Of the 604 clones analyzed, 45% were derived from genomic regions predicted to be noncoding. Additionally, at least 55% of the cDNA clones in this study were completely or partially antisense to known or predicted HCMV genes. The remarkable accumulation of antisense transcripts during infection suggests that currently available genomic maps based on open-reading-frame and other in silico analyses may drastically underestimate the true complexity of viral gene products. These findings also raise the possibility that aspects of both the HCMV life cycle and genome organization are influenced by antisense transcription. Correspondingly, virus-derived noncoding and antisense transcripts may shed light on HCMV pathogenesis and may represent a new class of targets for antiviral therapies.
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Affiliation(s)
- Guojuan Zhang
- The Ohio State University, Department of Pathology, 4162 Graves Hall, 333 West 10th Avenue, Columbus, OH 43210, USA
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37
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Petrik DT, Schmitt KP, Stinski MF. Inhibition of cellular DNA synthesis by the human cytomegalovirus IE86 protein is necessary for efficient virus replication. J Virol 2006; 80:3872-83. [PMID: 16571804 PMCID: PMC1440472 DOI: 10.1128/jvi.80.8.3872-3883.2006] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Human cytomegalovirus (HCMV) expresses several proteins that manipulate normal cellular functions, including cellular transcription, apoptosis, immune response, and cell cycle control. The IE2 gene, which is expressed from the HCMV major immediate-early (MIE) promoter, encodes the IE86 protein. IE86 is a multifunctional protein that is essential for viral replication. The functions of IE86 include transactivation of cellular and viral early genes, negative autoregulation of the MIE promoter, induction of cell cycle progression from G0/G1 to G1/S, and arresting cell cycle progression at the G1/S transition in p53-positive human foreskin fibroblast (HFF) cells. Mutations were introduced into the IE2 gene in the context of the viral genome using bacterial artificial chromosomes (BACs). From these HCMV BACs, a recombinant virus (RV) with a single amino acid substitution in the IE86 protein was isolated that replicates slower and to lower titers than wild-type HCMV. HFF cells infected with the Q548R RV undergo cellular DNA synthesis and do not arrest at any point in the cell cycle. The Q548R RV is able to negatively autoregulate the MIE promoter, transactivate viral early genes, activate cellular E2F-responsive genes, and produce infectious virus. This is the first report of a viable recombinant HCMV that is unable to inhibit cellular DNA synthesis in infected HFF cells.
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Affiliation(s)
- Dustin T Petrik
- Interdisciplinary Graduate Program in Molecular Biology, Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242, USA
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38
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DeMeritt IB, Podduturi JP, Tilley AM, Nogalski MT, Yurochko AD. Prolonged activation of NF-kappaB by human cytomegalovirus promotes efficient viral replication and late gene expression. Virology 2005; 346:15-31. [PMID: 16303162 PMCID: PMC2600890 DOI: 10.1016/j.virol.2005.09.065] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2005] [Revised: 08/12/2005] [Accepted: 09/23/2005] [Indexed: 01/04/2023]
Abstract
Infection of fibroblasts by human cytomegalovirus (HCMV) rapidly activates the NF-kappaB signaling pathway, which we documented promotes efficient transactivation of the major immediate-early promoter (DeMeritt, I.B., Milford, L.E., Yurochko, A.D. (2004). Activation of the NF-kappaB pathway in human cytomegalovirus-infected cells is necessary for efficient transactivation of the major immediate-early promoter. J. Virol. 78, 4498-4507). Because a second, sustained increase in NF-kappaB activity following the initial phase of NF-kappaB activation was also observed, we investigated the role that this prolonged NF-kappaB activation played in viral replication and late gene expression. We first investigated HCMV replication in cells in which NF-kappaB activation was blocked by pretreatment with NF-kappaB inhibitors: HCMV replication was significantly decreased in these cultures. A decrease in replication was also observed when NF-kappaB was inhibited up to 48 h post-infection, suggesting a previously unidentified role for NF-kappaB in the regulation of the later class of viral genes.
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Affiliation(s)
- Ian B. DeMeritt
- Department of Microbiology and Immunology and Center for Molecular and Tumor Virology, Louisiana State University Health Sciences Center, Shreveport, Louisiana 71130-3932
| | - Jagat P. Podduturi
- Department of Microbiology and Immunology and Center for Molecular and Tumor Virology, Louisiana State University Health Sciences Center, Shreveport, Louisiana 71130-3932
| | - A. Michael Tilley
- Department of Microbiology and Immunology and Center for Molecular and Tumor Virology, Louisiana State University Health Sciences Center, Shreveport, Louisiana 71130-3932
| | - Maciej T. Nogalski
- Department of Microbiology and Immunology and Center for Molecular and Tumor Virology, Louisiana State University Health Sciences Center, Shreveport, Louisiana 71130-3932
| | - Andrew D. Yurochko
- Department of Microbiology and Immunology and Center for Molecular and Tumor Virology, Louisiana State University Health Sciences Center, Shreveport, Louisiana 71130-3932
- Feist-Weiller Cancer Center, Louisiana State University Health Sciences Center, Shreveport, Louisiana 71130-3932
- *Corresponding Author: Department of Microbiology and Immunology, Louisiana State University Health Sciences Center, 1501 Kings Highway, Shreveport, LA 71130-3932, Phone: (318) 675-8332, Fax: (318) 675-5764, E-Mail:
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39
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White EA, Spector DH. Exon 3 of the human cytomegalovirus major immediate-early region is required for efficient viral gene expression and for cellular cyclin modulation. J Virol 2005; 79:7438-52. [PMID: 15919900 PMCID: PMC1143685 DOI: 10.1128/jvi.79.12.7438-7452.2005] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The human cytomegalovirus (HCMV) major immediate-early (IE) proteins share an 85-amino-acid N-terminal domain specified by exons 2 and 3 of the major IE region, UL122-123. We have constructed IE Delta30-77, a recombinant virus that lacks the majority of IE exon 3 and consequently expresses smaller forms of both IE1 72- and IE2 86-kDa proteins. The mutant virus is viable but growth impaired at both high and low multiplicities of infection and exhibits a kinetic defect that is not rescued by growth in fibroblasts expressing IE1 72-kDa protein. The kinetics of mutant IE2 protein accumulation in IE Delta30-77 virus-infected cells are approximately normal compared to wild-type virus-infected cells, but the IE Delta30-77 virus is delayed in expression of early viral genes, including UL112-113 and UL44, and does not sustain expression of mutant IE1 protein as the infection progresses. Additionally, cells infected with IE Delta30-77 exhibit altered expression of cellular proteins compared to wild-type HCMV-infected cells. PML is not dispersed but is retained at ND10 sites following infection with IE Delta30-77 mutant virus. While the deletion mutant retains the ability to mediate the stabilization of cyclin B1, cdc6, and geminin in infected cells, its capacity to upregulate the expression of cyclin E has been reduced. These data indicate that the activity of one or both of the HCMV major IE proteins is required in vivo for the modulation of cell cycle proteins observed in cells infected with wild-type HCMV.
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Affiliation(s)
- Elizabeth A White
- Dept. of Cellular and Molecular Medicine, Center for Molecular Genetics, University of California, San Diego, 9500 Gilman Dr., La Jolla, CA 92093, USA
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40
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Ghazal P, Visser AE, Gustems M, García R, Borst EM, Sullivan K, Messerle M, Angulo A. Elimination of ie1 significantly attenuates murine cytomegalovirus virulence but does not alter replicative capacity in cell culture. J Virol 2005; 79:7182-94. [PMID: 15890957 PMCID: PMC1112098 DOI: 10.1128/jvi.79.11.7182-7194.2005] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The major immediate-early (MIE) genes of cytomegaloviruses (CMV) are broadly thought to be decisive regulators of lytic replication and reactivation from latency. To directly assess the role of the MIE protein IE1 during the infection of murine CMV (MCMV), we constructed an MCMV with exon 4 of the ie1 gene deleted. We found that, independent of the multiplicity of infection, the resulting recombinant virus, MCMVdie1, which fails to express the IE1 protein, was fully competent for early gene expression and replicated in different cultured cell types with identical kinetics to those of parental or revertant virus. Immunofluorescence microscopy studies revealed that MCMVdie1 was greatly impaired in its capacity to disrupt promyelocytic leukemia bodies in NIH 3T3 cells early after infection, a process that has been proposed to increase viral transcription efficiency. We examined MCMVdie1 in the murine model using both immunocompetent BALB/c and severe combined immunodeficient (SCID) mice. When MCMVdie1 was inoculated into these two types of mice, significantly lower viral titers were detected in infected organs than in those of the wild-type virus-infected animals. Moreover, the ie1-deficient MCMV exhibited a markedly reduced virulence. While all animals infected with 5 x 10(4) PFU of parental virus died by 30 days postinfection, SCID mice infected with a similar dose of MCMVdie1 did not succumb before 60 days postinfection. The in vivo defective growth phenotype of MCMVdie1 was abrogated upon rescue of ie1. These results demonstrate the significance of the ie1 gene for promoting an acute MCMV infection and virulence yet indicate that MCMV is able to grow in vivo, although impaired, in the absence of the ie1 gene.
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Affiliation(s)
- Peter Ghazal
- Scottish Centre for Genomic Technology and Informatics, University of Edinburgh, Medical School, United Kingdom
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41
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Sadanari H, Yamada R, Ohnishi K, Matsubara K, Tanaka J. SUMO-1 modification of the major immediate-early (IE) 1 and 2 proteins of human cytomegalovirus is regulated by different mechanisms and modulates the intracellular localization of the IE1, but not IE2, protein. Arch Virol 2005; 150:1763-82. [PMID: 15931461 DOI: 10.1007/s00705-005-0559-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2004] [Accepted: 04/11/2005] [Indexed: 10/25/2022]
Abstract
We have previously shown that two proteins with apparent molecular masses of 91- and 102-kDa (p91 and p102, respectively) in human cytomegalovirus (HCMV)-infected cells are antigenically and structurally related to the major immediate-early (IE) 1 and 2 proteins (IE1p68 and IE2p80, respectively) of HCMV, respectively. In this study, we extended the characterization of p91 and p102 and our results were as follows; (i) Lysine at amino acid position 450 in IE1p68 and at amino acid position 175 or 180 in IE2p80, to which SUMO-1 has been shown to be covalently linked, are required for production of p91 and p102, respectively. (ii) A reversal of cycloheximide (CH) block in the presence of actinomycin D imposed at the time of infection inhibited production of p91, but not p102. (iii) The steady-state levels of p91, but not p102, were remarkably decreased by treatment with proteasome inhibitor MG132, but coincubation with CH inhibited this decrease of p91. (iv) Cell fractionation by differential detergent extraction demonstrated that p91 is preferentially found in detergent-insoluble fraction, although p102 as well as IE1p68 and IE2p80 distributes into all fractions. These results demonstrate that p91 and p102 correspond to SUMO-1-modified IE1p68 and IE2p80, respectively, that the production and degradation of SUMO-1-modified IE1p68 is regulated by mechanisms different from those of SUMO-1-modified IE2p80, and that SUMO-1 modification modulates the intracellular localization of IE1p68, but not IE2p80.
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Affiliation(s)
- H Sadanari
- Department of Microbiology, Faculty of Pharmaceutical Sciences, Hokuriku University, Kanazawa, Japan.
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42
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White EA, Clark CL, Sanchez V, Spector DH. Small internal deletions in the human cytomegalovirus IE2 gene result in nonviable recombinant viruses with differential defects in viral gene expression. J Virol 2004; 78:1817-30. [PMID: 14747546 PMCID: PMC369462 DOI: 10.1128/jvi.78.4.1817-1830.2004] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The human cytomegalovirus (HCMV) IE2 86-kDa protein is a key viral transactivator and an important regulator of HCMV infections. We used the HCMV genome cloned as a bacterial artificial chromosome (BAC) to construct four HCMV mutants with disruptions in regions of IE2 86 that are predicted to be important for its transactivation and autoregulatory functions. Three of these mutants have mutations that remove amino acids 356 to 359, 427 to 435, and 505 to 511, which disrupts a region of IE2 86 implicated in the activation of HCMV early promoters, a predicted zinc finger domain, and a putative helix-loop-helix motif, respectively, while the fourth carries three arginine-to-alanine substitution mutations in the region of amino acids 356 to 359. The resulting recombinant viruses are not viable, and by using quantitative real-time reverse transcription-PCR and immunofluorescence we have determined the location of the block in their replicative cycles. The IE2 86 Delta 356-359 mutant is able to support early gene expression, as indicated by the presence of UL112-113 transcripts and UL112-113 and UL44 proteins in cells transfected with the mutant BAC. This mutant does not express late genes and behaves nearly indistinguishably from the IE2 86R356/7/9A substitution mutant. Both exhibit detectable upregulation of major immediate-early transcripts at early times. The IE2 86 Delta 427-435 and IE2 86 Delta 505-511 recombinant viruses do not activate the early genes examined and are defective in repression of the major immediate-early promoter. These two mutants also induce the expression of selected delayed early (UL89) and late genes at early times in the infection. We conclude that these three regions of IE2 86 are necessary for productive infections and for differential control of downstream viral gene expression.
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Affiliation(s)
- Elizabeth A White
- Molecular Biology Section and Center for Molecular Genetics, University of California-San Diego, La Jolla, California 92093-0366, USA
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43
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Wara-Aswapati N, Boch JA, Auron PE. Activation of interleukin 1beta gene transcription by human cytomegalovirus: molecular mechanisms and relevance to periodontitis. ORAL MICROBIOLOGY AND IMMUNOLOGY 2003; 18:67-71. [PMID: 12654093 DOI: 10.1034/j.1399-302x.2003.00053.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
In recent years, studies have demonstrated an association between human cytomegalovirus (HCMV) and destructive periodontal disease. It has been shown that reactivation of HCMV in periodontitis lesions may be related to progressing periodontal disease. Several possible mechanisms by which HCMV exerts periodontopathic potential have been previously proposed. These are reviewed and include the upregulation of bone resorptive cytokines such as interleukin-1beta (IL-1beta) and tumor necrosis factor-alpha (TNF-alpha) by active HCMV infection at the periodontitis site. This review focuses on the molecular basis of IL-1beta gene activation by HCMV immediate early (IE) gene products. A novel hypothesis is also described whereby HCMV plays a significant role in the pathogenesis of periodontal disease by the ability of its IE proteins to strongly transactivate IL-1beta gene expression. More studies are needed to further explore this hypothesis and clarify the association between HCMV and periodontitis.
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Affiliation(s)
- N Wara-Aswapati
- Department of Periodontology, Faculty of Dentistry, Khon Kaen University, Khon Kaen, Thailand.
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Davison AJ, Dolan A, Akter P, Addison C, Dargan DJ, Alcendor DJ, McGeoch DJ, Hayward GS. The human cytomegalovirus genome revisited: comparison with the chimpanzee cytomegalovirus genome. J Gen Virol 2003; 84:17-28. [PMID: 12533697 DOI: 10.1099/vir.0.18606-0] [Citation(s) in RCA: 297] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
The gene complement of wild-type human cytomegalovirus (HCMV) is incompletely understood, on account of the size and complexity of the viral genome and because laboratory strains have undergone deletions and rearrangements during adaptation to growth in culture. We have determined the sequence (241 087 bp) of chimpanzee cytomegalovirus (CCMV) and have compared it with published HCMV sequences from the laboratory strains AD169 and Toledo, with the aim of clarifying the gene content of wild-type HCMV. The HCMV and CCMV genomes are moderately diverged and essentially collinear. On the basis of conservation of potential protein-coding regions and other sequence features, we have discounted 51 previously proposed HCMV ORFs, modified the interpretations for 24 (including assignments of multiple exons) and proposed ten novel genes. Several errors were detected in the published HCMV sequences. We presently recognize 165 genes in CCMV and 145 in AD169; this compares with an estimate of 189 unique genes for AD169 made in 1990. Our best estimate for the complement of wild-type HCMV is 164 to 167 genes.
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Affiliation(s)
- Andrew J Davison
- MRC Virology Unit, Institute of Virology, Church Street, Glasgow G11 5JR, UK
| | - Aidan Dolan
- MRC Virology Unit, Institute of Virology, Church Street, Glasgow G11 5JR, UK
| | - Parvis Akter
- MRC Virology Unit, Institute of Virology, Church Street, Glasgow G11 5JR, UK
| | - Clare Addison
- MRC Virology Unit, Institute of Virology, Church Street, Glasgow G11 5JR, UK
| | - Derrick J Dargan
- MRC Virology Unit, Institute of Virology, Church Street, Glasgow G11 5JR, UK
| | - Donald J Alcendor
- Molecular Virology Laboratories, Oncology Center, Johns Hopkins School of Medicine, Baltimore, MD 21231, USA
| | - Duncan J McGeoch
- MRC Virology Unit, Institute of Virology, Church Street, Glasgow G11 5JR, UK
| | - Gary S Hayward
- Molecular Virology Laboratories, Oncology Center, Johns Hopkins School of Medicine, Baltimore, MD 21231, USA
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Kumazaki K, Ozono K, Yahara T, Wada Y, Suehara N, Takeuchi M, Nakayama M. Detection of cytomegalovirus DNA in human placenta. J Med Virol 2002; 68:363-9. [PMID: 12226823 DOI: 10.1002/jmv.10212] [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: 11/11/2022]
Abstract
Although human cytomegalovirus (CMV) is one of the most common causes of viral intrauterine and perinatal infection, its distribution in the placenta is poorly understood. The purpose of this study was to determine the frequency of CMV DNA positivity in placentas, to demonstrate the localization of the viral genome, and to identify the clinical features related to placental CMV. A total of 254 placentas from 231 mothers were investigated, and the maternal serum CMV immunoglobulin antibodies were measured. Specimens from both the placental parenchyma and the placental membrane close to the ruptured site in each placenta were examined for the presence of CMV DNA using dot blot hybridization after PCR amplification. None of 57 placentas from seronegative mothers was positive for CMV DNA. Of 197 placentas from seropositive mothers, 60 (30.5%) had CMV DNA in either the parenchyma or the membrane by dot blot analysis. In situ hybridization was carried out on these 60 placentas, and the localization of the viral genome was established in 19; CMV DNA was localized mostly to the villi, including the mesenchyme and trophoblasts, extravillous trophoblasts, and decidual cells. The mean gestational age at delivery was significantly later in the CMV DNA-positive placentas than in the negative placentas (36.9 +/- 5.1 vs 34.7 +/- 6.2 weeks, P = 0.0059). CMV DNA was detected in only 6 of 33 placentas delivered in the second trimester, and all six were associated with either severe maternal nephritis or severe chorioamnionitis. These results suggest that the CMV genome is common in placentas at later gestational ages and in those of earlier gestational ages with certain maternal complications.
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Affiliation(s)
- Kaori Kumazaki
- Department of Pathology and Laboratory Medicine, Osaka Medical Center and Research Institute for Maternal and Child Health, Izumi, Osaka, Japan.
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Huang CH, Chen JY. Identification of additional IE2-p86-responsive cis-repressive sequences within the human cytomegalovirus major immediate early gene promoter. J Biomed Sci 2002; 9:460-70. [PMID: 12218362 DOI: 10.1007/bf02256541] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Human cytomegalovirus (HCMV) is a ubiquitous human pathogen that is the leading viral cause of birth defects and also causes significant morbidity and mortality in immunosuppressed individuals. The immediate early (IE) genes, IE1-p72 and IE2-p86, are the first HCMV genes expressed after infection under the control of a strong transcriptional enhancer-promoter, the major IE promoter (MIEP). Gene expression mediated by the predominant IE2-p86 is believed to be essential for the progression of viral production, as well as for the development of HCMV-associated pathogenesis. To gain further understanding of the transcriptional activity of IE2-p86, we attempted to isolate its downstream target genes within the HCMV genome. By a modified approach coupling the methods of cyclic amplification and selection of targets and selection and amplification of binding sites, several HCMV genomic fragments were identified based on their ability to bind to IE2-p86. Two additional IE2-p86-responsive elements other than the cis-repressive sequence (CRS) were identified within the MIEP and were termed -240 and -170 boxes. These two cis elements resemble the CRS in their sequences, as they contain the CG(N)(10)CG motif. The binding of IE2-p86 to these two distal CRS-like sequences was further confirmed by DNase I footprinting analysis and electrophoretic mobility shift assay. Promoter activity analysis in the transient expression system suggested that these two cis elements act functionally as IE2-p86-responsive repressive sequences to cooperate with the CRS to suppress MIEP expression.
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Affiliation(s)
- C H Huang
- Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan, ROC
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Abstract
It is widely accepted that small DNA tumor viruses, such as adenovirus, simian virus 40 and papillomavirus, push infected cells into S-phase to facilitate the replication of their genome. Until recently, it was believed that the large DNA viruses (i.e. herpesviruses) functioned very differently in this regard by inducing a G(1) arrest in infected cells as part of their replication process. However, studies over the last 6-8 years have uncovered striking parallels (and differences) between the functions of the major immediate early (IE) proteins of at least one herpesvirus, human cytomegalovirus (HCMV) and IE equivalents encoded by small DNA tumor viruses, such as adenovirus. Similarities between the HCMV major IE proteins and adenovirus IE proteins include targeting of members of the RB and p53 families and an ability of these viral factors to induce S-phase in quiescent cells. However, unlike the small DNA tumor virus proteins, individual HCMV IE proteins target different RB family members. HCMV also encodes several other IE gene products as well as virion tegument proteins that act early during infection to prevent an infected cell from replicating its host genome and from undergoing apoptosis. Here, we review the specifics of several HCMV IE proteins, two virion components, and their functions in relation to cell growth control.
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Affiliation(s)
- Jonathan P Castillo
- Program in Immunology and Virology, University of Massachusetts Medical School, 55 Lake Avenue North, Worcester, MA 01655, USA
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Gawn JM, Greaves RF. Absence of IE1 p72 protein function during low-multiplicity infection by human cytomegalovirus results in a broad block to viral delayed-early gene expression. J Virol 2002; 76:4441-55. [PMID: 11932411 PMCID: PMC155072 DOI: 10.1128/jvi.76.9.4441-4455.2002] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2001] [Accepted: 01/28/2002] [Indexed: 11/20/2022] Open
Abstract
Human cytomegalovirus (HCMV) ie1 deletion mutant CR208 is profoundly growth deficient after low-multiplicity infection of primary fibroblasts. Previously, we showed that many fewer cells infected with CR208 at low multiplicity accumulated the delayed-early (DE) protein ppUL44 than accumulated the immediate-early 2 (IE2) p86 protein, indicating a high frequency of abortive infections. We now demonstrate that accumulation of all DE proteins tested was defective after low-multiplicity infection in the absence of IE1 p72. Accumulation of the DE proteins pUL57, pUL98, and pUL69 followed a pattern very similar to that of ppUL44 during low-multiplicity CR208 infection. Accumulation of the ppUL112-113 proteins occurred in a greater proportion of cells than other DE proteins during low-multiplicity CR208 infection, but was still deficient relative to wild-type virus. We also show for the first time that steady-state levels of many DE RNAs were reduced during low-multiplicity CR208 infection and that by in situ hybridization of the abundant cytoplasmic 2.7-kb TRL4 DE (beta2.7) RNA, a viral DE RNA followed a defective pattern of accumulation similar to that of ppUL44. Furthermore, transfected DE promoter-reporter constructs were found in transient assays to be considerably less responsive to CR208 infection than to infection by wild-type Towne virus. Our results indicate a general defect in DE gene expression following low-multiplicity HCMV infection in the absence of functional IE1 p72, most probably mediated by reduced transcription of DE genes and by the reduced accumulation of DE RNAs.
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Affiliation(s)
- Jonathan M Gawn
- Department of Medicine, Cambridge University Clinical School, Addenbrooke's Hospital, Cambridge, United Kingdom
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Shirakata M, Terauchi M, Ablikim M, Imadome KI, Hirai K, Aso T, Yamanashi Y. Novel immediate-early protein IE19 of human cytomegalovirus activates the origin recognition complex I promoter in a cooperative manner with IE72. J Virol 2002; 76:3158-67. [PMID: 11884540 PMCID: PMC136045 DOI: 10.1128/jvi.76.7.3158-3167.2002] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2001] [Accepted: 12/29/2001] [Indexed: 11/20/2022] Open
Abstract
The major immediate-early (MIE) gene of human cytomegalovirus (HCMV) expresses IE86, IE72, IE55, and IE18 mRNA by differential splicing. Reverse transcription-PCR with IE72-specific primers generated an 0.65-kb cDNA from HCMV-infected fibroblast RNA, which does not correspond to any known MIE cDNA. Nucleotide sequencing revealed that the 0.65-kb cDNA is from exons 1, 2, and 3 and part of exon 4, indicating that it is derived from a novel alternatively spliced mRNA of the MIE gene. The cDNA encodes a 172-amino-acid polypeptide, termed IE19, which corresponds to an IE72 variant with an internal deletion from Val(86) to Pro(404) and appears as a band at 38 kDa on a sodium dodecyl sulfate-polyacrylamide gel. IE19 mRNA was expressed at a low level in the immediate-early, early, and late period of viral infection. IE19 was localized in nuclei, and a transient-expression assay revealed that IE19 enhances IE72-dependent activation of the HsOrc1 promoter, which is identified here as an IE72 target promoter. Another MIE protein, IE86, activated the same promoter but only weakly compared to IE72, and coexpression of IE19 did not alter the IE86-mediated transcriptional activation. In addition, IE19 did not enhance the IE72-dependent activation of the HCMV UL54 promoter. These results suggest that IE19 is a transcriptional coactivator that works with IE72.
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Affiliation(s)
- Masaki Shirakata
- Department of Tumor Virology, Division of Virology and Immunology, Medical Research Institute, Graduate School of Medicine, Tokyo Medical and Dental University, Bunkyo, Tokyo 113-8510, Japan.
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Kim JM, Ho SH, Park EJ, Hahn W, Cho H, Jeong JG, Lee YW, Kim S. Angiostatin gene transfer as an effective treatment strategy in murine collagen-induced arthritis. ARTHRITIS AND RHEUMATISM 2002; 46:793-801. [PMID: 11920417 DOI: 10.1002/art.10113] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
OBJECTIVE To determine the efficacy of local therapy with human angiostatin gene in murine collagen-induced arthritis (CIA). METHODS DBA/1 mice were immunized with bovine type II collagen. Before the onset of arthritis, NIH3T3 fibroblasts, transduced with angiostatin-expressing retroviral vectors or control vectors, were transplanted into the knee cavity. The incidence of arthritis in the knee joints was evaluated histologically based on pannus formation and cartilage destruction. Paws were evaluated macroscopically for redness, swelling, and deformities and immunologically for levels of interleukin-1 beta. Angiogenesis in paws and knee joints was studied by immunohistochemistry using anti-CD31 antibody and measurement of von Willebrand factor levels. RESULTS Pannus formation and cartilage erosion were dramatically reduced in knees transplanted with angiostatin-expressing cells. In addition, the onset of CIA in the ipsilateral paws below the knees injected with the angiostatin gene was significantly prevented. Furthermore, angiostatin gene transfer inhibited arthritis-associated angiogenesis. CONCLUSION Local production of angiostatin in the knee was able to prevent the onset of CIA not only in the knee injected with genetically engineered cells, but also in the uninjected ipsilateral paw. This suggests that transfer of the angiostatin gene, and potentially also its protein, may provide a new, effective approach to the treatment of rheumatoid arthritis.
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Affiliation(s)
- Jong-Mook Kim
- ViroMed Ltd. and Seoul National University, Kwak-Ak-Gu, Seoul, Korea
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