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Membraneless Compartmentalization of Nuclear Assembly Sites during Murine Cytomegalovirus Infection. Viruses 2023; 15:v15030766. [PMID: 36992475 PMCID: PMC10053344 DOI: 10.3390/v15030766] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Revised: 02/28/2023] [Accepted: 03/14/2023] [Indexed: 03/19/2023] Open
Abstract
Extensive reorganization of infected cells and the formation of large structures known as the nuclear replication compartment (RC) and cytoplasmic assembly compartment (AC) is a hallmark of beta-herpesvirus infection. These restructurings rely on extensive compartmentalization of the processes that make up the virus manufacturing chain. Compartmentalization of the nuclear processes during murine cytomegalovirus (MCMV) infection is not well described. In this study, we visualized five viral proteins (pIE1, pE1, pM25, pm48.2, and pM57) and replicated viral DNA to reveal the nuclear events during MCMV infection. As expected, these events can be matched with those described for other beta and alpha herpesviruses and contribute to the overall picture of herpesvirus assembly. Imaging showed that four viral proteins (pE1, pM25, pm48.2, and pM57) and replicated viral DNA condense in the nucleus into membraneless assemblies (MLAs) that undergo a maturation sequence to form the RC. One of these proteins (pM25), which is also expressed in a cytoplasmic form (pM25l), showed similar MLAs in the AC. Bioinformatics tools for predicting biomolecular condensates showed that four of the five proteins had a high propensity for liquid–liquid phase separation (LLPS), suggesting that LLPS may be a mechanism for compartmentalization within RC and AC. Examination of the physical properties of MLAs formed during the early phase of infection by 1,6-hexanediol treatment in vivo revealed liquid-like properties of pE1 MLAs and more solid-like properties of pM25 MLAs, indicating heterogeneity of mechanisms in the formation of virus-induced MLAs. Analysis of the five viral proteins and replicated viral DNA shows that the maturation sequence of RC and AC is not completed in many cells, suggesting that virus production and release is carried out by a rather limited number of cells. This study thus lays the groundwork for further investigation of the replication cycle of beta-herpesviruses, and the results should be incorporated into plans for high-throughput and single-cell analytic approaches.
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Štimac I, Jug Vučko N, Blagojević Zagorac G, Marcelić M, Mahmutefendić Lučin H, Lučin P. Dynamin Inhibitors Prevent the Establishment of the Cytomegalovirus Assembly Compartment in the Early Phase of Infection. Life (Basel) 2021; 11:life11090876. [PMID: 34575026 PMCID: PMC8469281 DOI: 10.3390/life11090876] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 08/21/2021] [Accepted: 08/23/2021] [Indexed: 12/30/2022] Open
Abstract
Cytomegalovirus (CMV) infection initiates massive rearrangement of cytoplasmic organelles to generate assembly compartment (AC). The earliest events, the establishment of the preAC, are initiated in the early phase as an extensive reorganization of early endosomes (EEs), endosomal recycling compartment (ERC), trans-Golgi network (TGN), and the Golgi. Here, we demonstrate that dynamin inhibitors (Dynasore, Dyngo-4a, MiTMAB, and Dynole-34-2) block the establishment of the preAC in murine CMV (MCMV) infected cells. In this study, we extensively analyzed the effect of Dynasore on the Golgi reorganization sequence into the outer preAC. We also monitored the development of the inner preAC using a set of markers that define EEs (Rab5, Vps34, EEA1, and Hrs), the EE-ERC interface (Rab10), the ERC (Rab11, Arf6), three layers of the Golgi (GRASP65, GM130, Golgin97), and late endosomes (Lamp1). Dynasore inhibited the pericentriolar accumulation of all markers that display EE-ERC-TGN interface in the inner preAC and prevented Golgi unlinking and dislocation to the outer preAC. Furthermore, in pulse-chase experiments, we demonstrated that the presence of dynasore only during the early phase of MCMV infection (4-14 hpi) is sufficient to prevent not only AC formation but also the synthesis of late-phase proteins and virion production. Therefore, our results indicate that dynamin-2 acts as a part of the machinery required for AC generation and rearrangement of EE/ERC/Golgi membranes in the early phase of CMV infection.
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Affiliation(s)
- Igor Štimac
- Department of Physiology and Immunology, Faculty of Medicine, University of Rijeka, 51000 Rijeka, Croatia; (I.Š.); (N.J.V.); (G.B.Z.); (M.M.); (P.L.)
| | - Natalia Jug Vučko
- Department of Physiology and Immunology, Faculty of Medicine, University of Rijeka, 51000 Rijeka, Croatia; (I.Š.); (N.J.V.); (G.B.Z.); (M.M.); (P.L.)
| | - Gordana Blagojević Zagorac
- Department of Physiology and Immunology, Faculty of Medicine, University of Rijeka, 51000 Rijeka, Croatia; (I.Š.); (N.J.V.); (G.B.Z.); (M.M.); (P.L.)
- Nursing Department, University North, University Center Varaždin, Jurja Križanića 31b, 42000 Varaždin, Croatia
| | - Marina Marcelić
- Department of Physiology and Immunology, Faculty of Medicine, University of Rijeka, 51000 Rijeka, Croatia; (I.Š.); (N.J.V.); (G.B.Z.); (M.M.); (P.L.)
| | - Hana Mahmutefendić Lučin
- Department of Physiology and Immunology, Faculty of Medicine, University of Rijeka, 51000 Rijeka, Croatia; (I.Š.); (N.J.V.); (G.B.Z.); (M.M.); (P.L.)
- Nursing Department, University North, University Center Varaždin, Jurja Križanića 31b, 42000 Varaždin, Croatia
- Correspondence:
| | - Pero Lučin
- Department of Physiology and Immunology, Faculty of Medicine, University of Rijeka, 51000 Rijeka, Croatia; (I.Š.); (N.J.V.); (G.B.Z.); (M.M.); (P.L.)
- Nursing Department, University North, University Center Varaždin, Jurja Križanića 31b, 42000 Varaždin, Croatia
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Kutle I, Szymańska-de Wijs KM, Bogdanow B, Cuvalo B, Steinbrück L, Jonjić S, Wagner K, Niedenthal R, Selbach M, Wiebusch L, Dezeljin M, Messerle M. Murine Cytomegalovirus M25 Proteins Sequester the Tumor Suppressor Protein p53 in Nuclear Accumulations. J Virol 2020; 94:e00574-20. [PMID: 32727874 PMCID: PMC7527045 DOI: 10.1128/jvi.00574-20] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Accepted: 07/22/2020] [Indexed: 02/06/2023] Open
Abstract
To ensure productive infection, herpesviruses utilize tegument proteins and nonstructural regulatory proteins to counteract cellular defense mechanisms and to reprogram cellular pathways. The M25 proteins of mouse cytomegalovirus (MCMV) belong to the betaherpesvirus UL25 gene family that encodes viral proteins implicated with regulatory functions. Through affinity purification and mass spectrometric analysis, we discovered the tumor suppressor protein p53 as a host factor interacting with the M25 proteins. M25-p53 interaction in infected and transfected cells was confirmed by coimmunoprecipitation. Moreover, the proteins colocalized in nuclear dot-like structures upon both infection and inducible expression of the two M25 isoforms. p53 accumulated in wild-type MCMV-infected cells, while this did not occur upon infection with a mutant lacking the M25 gene. Both M25 proteins were able to mediate the effect, identifying them as the first CMV proteins responsible for p53 accumulation during infection. Interaction with M25 proteins led to substantial prolongation of the half-life of p53. In contrast to the higher abundance of the p53 protein in wild-type MCMV-infected cells, the transcript levels of the prominent p53 target genes Cdkn1a and Mdm2 were diminished compared to cells infected with the ΔM25 mutant, and this was associated with reduced binding of p53 to responsive elements within the respective promoters. Notably, the productivity of the M25 deletion mutant was partially rescued on p53-negative fibroblasts. We propose that the MCMV M25 proteins sequester p53 molecules in the nucleus of infected cells, reducing their availability for activating a subset of p53-regulated genes, thereby dampening the antiviral role of p53.IMPORTANCE Host cells use a number of factors to defend against viral infection. Viruses are, however, in an arms race with their host cells to overcome these defense mechanisms. The tumor suppressor protein p53 is an important sensor of cell stress induced by oncogenic insults or viral infections, which upon activation induces various pathways to ensure the integrity of cells. Viruses have to counteract many functions of p53, but complex DNA viruses such as cytomegaloviruses may also utilize some p53 functions for their own benefit. In this study, we discovered that the M25 proteins of mouse cytomegalovirus interact with p53 and mediate its accumulation during infection. Interaction with the M25 proteins sequesters p53 molecules in nuclear dot-like structures, limiting their availability for activation of a subset of p53-regulated target genes. Understanding the interaction between viral proteins and p53 may allow to develop new therapeutic strategies against cytomegalovirus and other viruses.
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Affiliation(s)
- Ivana Kutle
- Institute of Virology, Hannover Medical School, Hannover, Germany
| | | | - Boris Bogdanow
- Proteome Dynamics lab, Max Delbrück Center for Molecular Medicine, Berlin, Germany
- Department of Chemical Biology, Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Berlin, Germany
| | - Berislav Cuvalo
- Institute of Virology, Hannover Medical School, Hannover, Germany
| | - Lars Steinbrück
- Institute of Virology, Hannover Medical School, Hannover, Germany
| | - Stipan Jonjić
- Department of Histology and Embryology, Faculty of Medicine, University of Rijeka, Rijeka, Croatia
| | - Karen Wagner
- Institute of Virology, Hannover Medical School, Hannover, Germany
| | - Rainer Niedenthal
- Institute of Cell Biochemistry, Hannover Medical School, Hannover, Germany
| | - Matthias Selbach
- Proteome Dynamics lab, Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Lüder Wiebusch
- Laboratory of Pediatric Molecular Biology, Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Martina Dezeljin
- Institute of Virology, Hannover Medical School, Hannover, Germany
| | - Martin Messerle
- Institute of Virology, Hannover Medical School, Hannover, Germany
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4
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Cruz-cosme R, Armstrong N, Tang Q. One of the Triple Poly(A) Signals in the M112-113 Gene Is Important and Sufficient for Stabilizing the M112-113 mRNA and the Replication of Murine Cytomegalovirus. Viruses 2020; 12:E954. [PMID: 32872150 PMCID: PMC7552018 DOI: 10.3390/v12090954] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Revised: 08/25/2020] [Accepted: 08/27/2020] [Indexed: 11/17/2022] Open
Abstract
The M112-113 gene is the first early gene of the murine cytomegalovirus (MCMV), and its expression is activated by the immediate-early 3 (IE3) protein during MCMV infection in permissive cells. At its 5' terminus, a 10-bp motif, upstream of the TATA box of the M112-113 gene, was identified to bind to IE3, and it is necessary for IE3 to activate M112-113 gene expression (Perez KJ et al. 2013 JVI). At the 3' terminus of the M112-113 gene, three poly(A) signals (PASs) are arranged closely, forming a PAS cluster. We asked whether it is necessary to have the PAS cluster for the M112-113 gene and wondered which PAS is required or important for M112-113 gene expression. In this study, we mutated one, two, or all three PASs in expressing plasmids. Then, we applied bacterial artificial chromosome (BAC) techniques to mutate PASs in viruses. Gene expression and viral replication were analyzed. We found that not all three PASs are needed for M112-113 gene expression. Moreover, we revealed that just one of the three poly(A)s is enough for MCMV replication. However, the deletion of all three PASs did not kill MCMV, although it significantly attenuated viral replication. Finally, an mRNA stability assay was performed and demonstrated that PASs are important to stabilize M112-113 mRNA. Therefore, we conclude that just one of the PASs of the M112-113 gene is sufficient and important for MCMV replication through the stabilization of M112-113 mRNA.
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Affiliation(s)
| | | | - Qiyi Tang
- Department of Microbiology, College of Medicine, Howard University, 520 W Street NW, Washington, DC 20059, USA; (R.C.-c.); (N.A.)
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Kutle I, Sengstake S, Templin C, Glaß M, Kubsch T, Keyser KA, Binz A, Bauerfeind R, Sodeik B, Čičin-Šain L, Dezeljin M, Messerle M. The M25 gene products are critical for the cytopathic effect of mouse cytomegalovirus. Sci Rep 2017; 7:15588. [PMID: 29138436 PMCID: PMC5686157 DOI: 10.1038/s41598-017-15783-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Accepted: 11/02/2017] [Indexed: 12/22/2022] Open
Abstract
Cell rounding is a hallmark of the cytopathic effect induced by cytomegaloviruses. By screening a panel of deletion mutants of mouse cytomegalovirus (MCMV) a mutant was identified that did not elicit cell rounding and lacked the ability to form typical plaques. Altered cell morphology was assigned to the viral M25 gene. We detected an early 2.8 kb M25 mRNA directing the synthesis of a 105 kDa M25 protein, and confirmed that a late 3.1 kb mRNA encodes a 130 kDa M25 tegument protein. Virions lacking the M25 tegument protein were of smaller size because the tegument layer between capsid and viral envelope was reduced. The ΔM25 mutant did not provoke the rearrangement of the actin cytoskeleton observed after wild-type MCMV infection, and isolated expression of the M25 proteins led to cell size reduction, confirming that they contribute to the morphological changes. Yields of progeny virus and cell-to-cell spread of the ΔM25 mutant in vitro were diminished and replication in vivo was impaired. The identification of an MCMV gene involved in cell rounding provides the basis for investigating the role of this cytopathic effect in CMV pathogenesis.
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Affiliation(s)
- Ivana Kutle
- Institute of Virology, Hannover Medical School, 30625, Hannover, Germany
| | - Sarah Sengstake
- Institute of Virology, Hannover Medical School, 30625, Hannover, Germany
- Unit of Mycobacteriology, Institute of Tropical Medicine, 2000, Antwerp, Belgium
| | - Corinna Templin
- Institute of Virology, Hannover Medical School, 30625, Hannover, Germany
| | - Mandy Glaß
- Institute of Virology, Hannover Medical School, 30625, Hannover, Germany
- Institute for Biomedical and Health Research, University of the West of Scotland, PA1 2BE, Paisley, Scotland, UK
- Centre for Virus Research, University of Glasgow, G61 1QH, Glasgow, Scotland, UK
| | - Tobias Kubsch
- Helmholtz Centre for Infection Research, 38124, Braunschweig, Germany
| | - Kirsten A Keyser
- Institute of Virology, Hannover Medical School, 30625, Hannover, Germany
| | - Anne Binz
- Institute of Virology, Hannover Medical School, 30625, Hannover, Germany
| | - Rudolf Bauerfeind
- Central Core Unit for Laser Microscopy, Hannover Medical School, 30625, Hannover, Germany
| | - Beate Sodeik
- Institute of Virology, Hannover Medical School, 30625, Hannover, Germany
| | - Luka Čičin-Šain
- Institute of Virology, Hannover Medical School, 30625, Hannover, Germany
- Helmholtz Centre for Infection Research, 38124, Braunschweig, Germany
| | - Martina Dezeljin
- Institute of Virology, Hannover Medical School, 30625, Hannover, Germany
| | - Martin Messerle
- Institute of Virology, Hannover Medical School, 30625, Hannover, Germany.
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Seminal plasma and semen amyloids enhance cytomegalovirus infection in cell culture. J Virol 2013; 87:12583-91. [PMID: 24027327 DOI: 10.1128/jvi.02083-13] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Among the modes of transmission available to the cytomegalovirus (CMV) is sexual transmission, primarily via semen. Both male-to-female (M-F) and male-to-male (M-M) sexual transmission significantly contribute toward the spread of CMV infections in the global population. Semen plays an important role in carrying the viral particle that invades the vaginal or rectal mucosa, thereby initiating viral replication. Both semen and seminal plasma (SP) can enhance HIV-1 infection in cell culture, and two amyloid fibrils, semen-derived enhancer of viral infection (SEVI) and amyloids derived from the semenogelins (SEM amyloids), have been identified as seminal factors sufficient to enhance HIV-1 infection (J. Munch et al., Cell 131:1059-1071, 2007; N. R. Roan et al., Cell Host Microbe 10:541-550, 2011; F. Arnold et al., J. Virol. 86:1244-1249, 2012). Whether SP, SEVI, or SEM amyloids can enhance other viral infections has not been extensively examined. In this study, we found that SP, SEVI, and SEM amyloids strongly enhance both human CMV (HCMV) and murine CMV infection in cell culture. SEVI and SEM amyloids increased infection rates by >10-fold, as determined by both flow cytometry and fluorescence microscopy. Viral replication was increased by 50- to 100-fold. Moreover, viral growth curve assays showed that SP, SEVI, and SEM amyloids sped up the kinetics of CMV replication such that the virus reached its replicative peak more quickly. Finally, we discovered that SEM amyloids and SEVI counteracted the effect of anti-gH in protecting against CMV infection. Collectively, the data suggest that semen enhances CMV infection through interactions between semen amyloid fibrils and viral particles, and these interactions may prevent HCMV from being neutralized by anti-gH antibody.
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A short cis-acting motif in the M112-113 promoter region is essential for IE3 to activate M112-113 gene expression and is important for murine cytomegalovirus replication. J Virol 2012; 87:2639-47. [PMID: 23255797 DOI: 10.1128/jvi.03171-12] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Immediate-early 3 (IE3) gene products are required to activate early (E)-stage gene expression of murine cytomegaloviruses (MCMV). The first early gene activated by IE3 is the M112-113 gene (also called E1), although a complete understanding of the activation mechanism is still lacking. In this paper, we identify a 10-bp cis-regulating motif upstream of the M112-113 TATA box as important for IE3 activation of M112-113 expression. Results from DNA affinity assays and chromatin immunoprecipitation assays show that the association of IE3 with the M112-113 gene promoter was eliminated by deletion of the 10-bp DNA sequence, now named IE3AM (for IE3 activating motif). In addition, IE3 interacts with TATA box binding protein (TBP), a core protein of TFIID (transcription initiation) complexes. Finally, we created an IE3AM-deleted MCMV (MCMVdIE3AM) using a bacterial artificial chromosome system. The mutant virus can still replicate in NIH 3T3 cells but at a significantly lower level. The defectiveness of the MCMVdIE3AM infection can be rescued in an M112-113-complemented cell line. Our results suggest that the interactions of IE3 with IE3AM and with TBP stabilize the TFIID complex at the M112-113 promoter such that M112-113 gene expression can be activated and/or enhanced.
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Tsen SWD, Chapa T, Beatty W, Tsen KT, Yu D, Achilefu S. Inactivation of enveloped virus by laser-driven protein aggregation. JOURNAL OF BIOMEDICAL OPTICS 2012; 17:128002. [PMID: 23224114 PMCID: PMC3518210 DOI: 10.1117/1.jbo.17.12.128002] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Ultrafast lasers in the visible and near-infrared range have emerged as a potential new method for pathogen reduction of blood products and pharmaceuticals. However, the mechanism of enveloped virus inactivation by this method is unknown. We report the inactivation as well as the molecular and structural effects caused by visible (425 nm) femtosecond laser irradiation on murine cytomegalovirus (MCMV), an enveloped, double-stranded DNA virus. Our results show that laser irradiation (1) caused a 5-log reduction in MCMV titer, (2) did not cause significant changes to the global structure of MCMV virions including membrane and capsid, as assessed by electron microscopy, (3) produced no evidence of double-strand breaks or crosslinking in MCMV genomic DNA, and (4) caused selective aggregation of viral capsid and tegument proteins. We propose a model in which ultrafast laser irradiation induces partial unfolding of viral proteins by disrupting hydrogen bonds and/or hydrophobic interactions, leading to aggregation of closely associated viral proteins and inactivation of the virus. These results provide new insight into the inactivation of enveloped viruses by visible femtosecond lasers at the molecular level, and help pave the way for the development of a new ultrafast laser technology for pathogen reduction.
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Affiliation(s)
- Shaw-Wei D. Tsen
- Washington University School of Medicine, Department of Radiology, St. Louis, Missouri 63110
| | - Travis Chapa
- Washington University School of Medicine, Department of Molecular Microbiology, St. Louis, Missouri 63110
| | - Wandy Beatty
- Washington University School of Medicine, Department of Molecular Microbiology, St. Louis, Missouri 63110
| | - Kong-Thon Tsen
- Arizona State University, Department of Physics, Tempe, Arizona 85287
- Arizona State University, Center for Biophysics, Tempe, Arizona 85287
- Address correspondence to: Samuel Achilefu, Washington University School of Medicine, Department of Radiology, St. Louis, Missouri 63110. Tel: 314-362-8599; Fax: 314-747-5191; E-mail: , or Kong-Thon Tsen, Arizona State University, Department of Physics, Tempe, Arizona 85287. Tel: 480-965-5206; Fax: 480-965-7954;
| | - Dong Yu
- Washington University School of Medicine, Department of Molecular Microbiology, St. Louis, Missouri 63110
| | - Samuel Achilefu
- Washington University School of Medicine, Department of Radiology, St. Louis, Missouri 63110
- Washington University School of Medicine, Department of Biochemistry and Molecular Biophysics, St. Louis, Missouri 63110
- Washington University School of Medicine, Department of Biomedical Engineering, St. Louis, Missouri 63110
- Address correspondence to: Samuel Achilefu, Washington University School of Medicine, Department of Radiology, St. Louis, Missouri 63110. Tel: 314-362-8599; Fax: 314-747-5191; E-mail: , or Kong-Thon Tsen, Arizona State University, Department of Physics, Tempe, Arizona 85287. Tel: 480-965-5206; Fax: 480-965-7954;
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9
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Temporal profiling of the coding and noncoding murine cytomegalovirus transcriptomes. J Virol 2011; 85:6065-76. [PMID: 21471238 DOI: 10.1128/jvi.02341-10] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The global transcriptional program of murine cytomegalovirus (MCMV), involving coding, noncoding, and antisense transcription, remains unknown. Here we report an oligonucleotide custom microarray platform capable of measuring both coding and noncoding transcription on a genome-wide scale. By profiling MCMV wild-type and immediate-early mutant strains in fibroblasts, we found rapid activation of the transcriptome by 6.5 h postinfection, with absolute dependency on ie3, but not ie1 or ie2, for genomic programming of viral gene expression. Evidence is also presented to show, for the first time, genome-wide noncoding and bidirectional transcription at late stages of MCMV infection.
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10
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Martínez FP, Cosme RSC, Tang Q. Murine cytomegalovirus major immediate-early protein 3 interacts with cellular and viral proteins in viral DNA replication compartments and is important for early gene activation. J Gen Virol 2010; 91:2664-76. [PMID: 20631086 PMCID: PMC3052557 DOI: 10.1099/vir.0.022301-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Murine cytomegalovirus (MCMV) immediate-early protein 3 (IE3) is essential for successful viral infection. This study developed MCMVs with an EGFP-fused IE3 gene in order to study IE3 gene expression, subnuclear distribution and biological function, as well as to examine the interaction of IE3 with cellular and viral proteins. The generated viruses included MCMVIE3gfp, in which IE1 was completely removed by the in-frame fusion of exons 3 and 5 and the C terminus of IE3 was tagged with EGFP, and MCMVIE1/3gfp, in which IE1 was kept intact and EGFP was also fused to the C terminus of IE3. Unlike human CMV (HCMV), whose growth was significantly reduced when IE2 (the HCMV homologue of IE3 in MCMV) was tagged with EGFP, MCMVs with IE3–EGFP presented an unchanged replication profile. Using these new constructs, the distribution of IE3 was revealed as well as its interaction with viral and cellular proteins, especially proteins pertaining to DNA replication (M44 and E1) and cellular intrinsic defence [promyelocytic leukemia protein and histone deacetylases (HDACs)]. It was also shown that IE3 domains co-localize with DNA replication domains, and IE3 attracted other required proteins into IE3 domains via protein–protein interactions. In addition, IE3 was shown to interact with HDAC2 and to eliminate the inhibitory effect of HDAC2 on early viral gene production. Together, these results suggest that IE3 acts as a key protein for viral DNA replication by establishing pre-replication domains via recruitment of the required viral and cellular proteins, and by reducing host defences.
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Murine cytomegalovirus capsid assembly is dependent on US22 family gene M140 in infected macrophages. J Virol 2009; 83:7449-56. [PMID: 19458005 DOI: 10.1128/jvi.00325-09] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Macrophages are an important target cell for infection with cytomegalovirus (CMV). A number of viral genes that either are expressed specifically in this cell type or function to optimize CMV replication in this host cell have now been identified. Among these is the murine CMV (MCMV) US22 gene family member M140, a nonessential early gene whose deletion (RVDelta140) leads to significant impairment in virus replication in differentiated macrophages. We have now determined that the defect in replication is at the stage of viral DNA encapsidation. Although the rate of RVDelta140 genome replication and extent of DNA cleavage were comparable to those for revertant virus, deletion of M140 resulted in a significant reduction in the number of viral capsids in the nucleus, and the viral DNA remained sensitive to DNase treatment. These data are indicative of incomplete virion assembly. Steady-state levels of both the major capsid protein (M86) and tegument protein M25 were reduced in the absence of the M140 protein (pM140). This effect may be related to the localization of pM140 to an aggresome-like, microtubule organizing center-associated structure that is known to target misfolded and overexpressed proteins for degradation. It appears, therefore, that pM140 indirectly influences MCMV capsid formation in differentiated macrophages by regulating the stability of viral structural proteins.
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Walton SM, Wyrsch P, Munks MW, Zimmermann A, Hengel H, Hill AB, Oxenius A. The dynamics of mouse cytomegalovirus-specific CD4 T cell responses during acute and latent infection. THE JOURNAL OF IMMUNOLOGY 2008; 181:1128-34. [PMID: 18606665 DOI: 10.4049/jimmunol.181.2.1128] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The dynamics of mouse cytomegalovirus (MCMV)-specific CD4 T cell responses and the mechanisms by which these cells contribute to viral control are not well understood, mainly due to lack of appropriate tools to characterize MCMV-specific CD4 T cells. We therefore generated MCMV-specific CD4 T cell hybridomas, then used an MCMV expression library and overlapping peptides to identify CD4 T cell epitopes. We used these novel tools to study the long-term kinetics and organ distribution of MCMV-specific CD4 T cells in comparison to MCMV-specific CD8 T cell responses. We demonstrate that the overall MCMV-specific CD4 T cell response stabilizes during the latent stage, which stands in contrast to subpopulations of MCMV-specific CD8 T cells and HCMV-specific CD4 T cells which accumulate over the course of CMV latency. Furthermore, MCMV-specific CD4 T cells displayed a Th1 phenotype, secreting high levels of IFN-gamma and TNF-alpha and to some extent IL-2, cytokines which are involved in protection from CMV disease.
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Affiliation(s)
- Senta M Walton
- Institute of Microbiology, Swiss Federal Institute of Technology, Zurich, Switzerland
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Brocchieri L, Kledal TN, Karlin S, Mocarski ES. Predicting coding potential from genome sequence: application to betaherpesviruses infecting rats and mice. J Virol 2005; 79:7570-96. [PMID: 15919911 PMCID: PMC1143683 DOI: 10.1128/jvi.79.12.7570-7596.2005] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Prediction of protein-coding regions and other features of primary DNA sequence have greatly contributed to experimental biology. Significant challenges remain in genome annotation methods, including the identification of small or overlapping genes and the assessment of mRNA splicing or unconventional translation signals in expression. We have employed a combined analysis of compositional biases and conservation together with frame-specific G+C representation to reevaluate and annotate the genome sequences of mouse and rat cytomegaloviruses. Our analysis predicts that there are at least 34 protein-coding regions in these genomes that were not apparent in earlier annotation efforts. These include 17 single-exon genes, three new exons of previously identified genes, a newly identified four-exon gene for a lectin-like protein (in rat cytomegalovirus), and 10 probable frameshift extensions of previously annotated genes. This expanded set of candidate genes provides an additional basis for investigation in cytomegalovirus biology and pathogenesis.
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Affiliation(s)
- Luciano Brocchieri
- Department of Mathematics, Stanford University, Stanford, CA 94305-2125, USA.
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Kattenhorn LM, Mills R, Wagner M, Lomsadze A, Makeev V, Borodovsky M, Ploegh HL, Kessler BM. Identification of proteins associated with murine cytomegalovirus virions. J Virol 2004; 78:11187-97. [PMID: 15452238 PMCID: PMC521832 DOI: 10.1128/jvi.78.20.11187-11197.2004] [Citation(s) in RCA: 118] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Proteins associated with the murine cytomegalovirus (MCMV) viral particle were identified by a combined approach of proteomic and genomic methods. Purified MCMV virions were dissociated by complete denaturation and subjected to either separation by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and in-gel digestion or treated directly by in-solution tryptic digestion. Peptides were separated by nanoflow liquid chromatography and analyzed by tandem mass spectrometry (LC-MS/MS). The MS/MS spectra obtained were searched against a database of MCMV open reading frames (ORFs) predicted to be protein coding by an MCMV-specific version of the gene prediction algorithm GeneMarkS. We identified 38 proteins from the capsid, tegument, glycoprotein, replication, and immunomodulatory protein families, as well as 20 genes of unknown function. Observed irregularities in coding potential suggested possible sequence errors in the 3'-proximal ends of m20 and M31. These errors were experimentally confirmed by sequencing analysis. The MS data further indicated the presence of peptides derived from the unannotated ORFs ORF(c225441-226898) (m166.5) and ORF(105932-106072). Immunoblot experiments confirmed expression of m166.5 during viral infection.
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Affiliation(s)
- Lisa M Kattenhorn
- Pathology Functional Proteomics Center, Department of Pathology, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115, USA
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Sobue T, Gravely T, Hand A, Min YK, Pilbeam C, Raisz LG, Zhang X, Larocca D, Florkiewicz R, Hurley MM. Regulation of fibroblast growth factor 2 and fibroblast growth factor receptors by transforming growth factor beta in human osteoblastic MG-63 cells. J Bone Miner Res 2002; 17:502-12. [PMID: 11874241 DOI: 10.1359/jbmr.2002.17.3.502] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Fibroblast growth factor 2 (FGF-2) and its receptors (FGFRs) are important regulators of bone cell function. Although FGF-2 is a major modulator of bone cell function, its expression and regulation in human osteoblasts have not been investigated. We examined FGF-2 messenger RNA (mRNA) expression and regulation in the human osteosarcoma MG-63 cells. Northern analysis revealed that MG-63 cells expressed FGF-2 mRNA transcripts of 7, 4, 2.2, and 1.3 kilobases (kb). In the absence of serum, treatment with transforming growth factor beta (TGF-beta; 0.1-10 ng/ml) increased all FGF-2 mRNA transcripts. Maximal increase was seen with 1 ng/ml of TGF-beta. TGF-beta increased FGF-2 mRNA expression within 2 h and this was sustained for 24 h. Phorbal myristate acetate (PMA; 1 microM) also increased FGF-2 mRNA at 6 h. Time course studies showed that TGF-beta did not significantly alter FGFR1 or FGFR2 mRNA expression in MG-63 cells. Western blotting with anti-human FGF-2 revealed that MG-63 cells synthesize three isoforms of FGF-2 protein of approximately 18, 22/23, and 24 kDa, which were increased after either 6 h or 24 h of treatment with TGF-beta. Increased FGF-2 mRNA and protein expression in response to TGF-beta was markedly reduced by the protein kinase A (PKA) inhibitor H-89. Immunogold labeling of MG-63 cells treated with TGF-beta showed increased labeling for FGF-2 and FGFR2 in the nuclei. In contrast, TGF-beta treatment significantly decreased FGFR1 labeling in the nuclei. These data show that TGF-beta regulates FGF-2 gene expression in human osteosarcoma cells. Furthermore, TGF-beta modulates the cellular localization of FGF-2 and its receptors.
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Affiliation(s)
- T Sobue
- University of Connecticut School of Medicine, Farmington, USA
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Lee M, Xiao J, Haghjoo E, Zhan X, Abenes G, Tuong T, Dunn W, Liu F. Murine cytomegalovirus containing a mutation at open reading frame M37 is severely attenuated in growth and virulence in vivo. J Virol 2000; 74:11099-107. [PMID: 11070005 PMCID: PMC113190 DOI: 10.1128/jvi.74.23.11099-11107.2000] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A pool of murine cytomegalovirus (MCMV) mutants was generated by using a Tn3-based transposon mutagenesis procedure. One of the mutants, RvM37, which contained the transposon sequence at open reading frame M37, was characterized both in tissue culture and in immunocompetent BALB/c and immunodeficient SCID mice. Our results provide the first direct evidence to suggest that M37 is not essential for viral replication in vitro in NIH 3T3 cells. Compared to the wild-type strain and a rescued virus that restored the M37 region, the viral mutant was severely attenuated in growth in both BALB/c and SCID mice after intraperitoneal infection. Specifically, titers of the Smith strain and rescued virus in the salivary glands, lungs, spleens, livers, and kidneys of the SCID mice at 21 days postinfection were about 5 x 10(5), 2 x 10(5), 5 x 10(4), 5 x 10(3), and 1 x 10(4) PFU/ml of organ homogenate, respectively; in contrast, titers of RvM37 in these organs were less than 10(2) PFU/ml of organ homogenate. Moreover, the virulence of the mutant virus appeared to be significantly attenuated because none of the SCID mice infected with RvM37 had died by 120 days postinfection, while all animals infected with the wild-type and rescued viruses had died by 26 days postinfection. Our results suggest that M37 probably encodes a virulence factor and is required for MCMV virulence in SCID mice and for optimal viral growth in vivo.
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Affiliation(s)
- M Lee
- Program in Infectious Diseases and Immunity, School of Public Health, University of California, Berkeley, California 94720, USA
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Abstract
We have determined the complete genome sequence of the Maastricht strain of rat cytomegalovirus (RCMV). The RCMV genome has a length of 229,896 bp and is arranged as a single unique sequence flanked by 504-bp terminal direct repeats. RCMV was found to have counterparts of all but one of the open reading frames (ORFs) that are conserved between murine CMV (MCMV) and human CMV (HCMV). Like HCMV, RCMV lacks homologs of the genes belonging to the MCMV m02 glycoprotein gene family. However, RCMV contains 15 ORFs with homology to members of the MCMV m145 glycoprotein gene family. Four ORFs are predicted to encode homologs of host proteins; R33 and R78 both putatively encode G protein-coupled receptors, whereas r144 and r131 encode homologs of major histocompatibility class I heavy chains and CC chemokines, respectively. An intriguing feature of the RCMV genome is the presence of an ORF, r127, with similarity to the rep gene of parvoviruses as well as ORF U94 of human herpesvirus 6A (HHV-6A) and HHV-6B. Counterparts of these ORFs have not been found in the other sequenced herpesviruses.
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Affiliation(s)
- C Vink
- Department of Medical Microbiology, Cardiovascular Research Institute Maastricht, University of Maastricht, 6202 AZ Maastricht, The Netherlands.
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