scholarly journals Mouse Cytomegalovirus Immediate-Early Protein 1 Binds with Host Cell Repressors To Relieve Suppressive Effects on Viral Transcription and Replication during Lytic Infection

2003 ◽  
Vol 77 (2) ◽  
pp. 1357-1367 ◽  
Author(s):  
Qiyi Tang ◽  
Gerd G. Maul
Keyword(s):  
Promoter Region ◽  
Trichostatin A ◽  
Immediate Early ◽  
Productive Infection ◽  
Mouse Cytomegalovirus ◽  
Viral Genomes ◽  
Histone Deacetylase 2 ◽  
Early Protein ◽  
Repressive Effect ◽  
In Cells

ABSTRACT Herpesviruses start their transcriptional cascade at nuclear domain 10 (ND10). The deposition of virus genomes at these nuclear sites occurs due to the binding of the interferon-inducible repressor protein promyelocytic leukemia protein (PML) and/or Daxx to a viral DNA-protein complex. However, the presence of repressive proteins at the nuclear site of virus transcription has remained unexplained. We investigated the mouse cytomegalovirus (MCMV) immediate-early 1 protein (IE1), which is necessary for productive infection at low multiplicities of infection and therefore likely to be involved in overcoming cellular repression. Temporal analysis of IE1 distribution revealed its initial segregation into ND10 by binding to PML and/or Daxx and IE1-dependent recruitment of the transcriptional repressor histone deacetylase-2 (HDAC-2) to this site. However, these protein aggregates are dissociated in cells producing sufficient IE1 through titration of PML, Daxx, and HDAC-2. Importantly, binding of IE1 to HDAC-2 decreased deacetylation activity. Moreover, inhibition of HDAC by trichostatin-A resulted in an increase in viral protein synthesis, an increase in cells starting the formation of prereplication compartments, and an increase in the total infectious viruses produced. Thus, IE1, like trichostatin-A, reverses the repressive effect of HDAC evident in the presence of acetylated histones in the immediate-early promoter region. Since HDAC also binds to the promoter region of IE1, as determined by the chromatin immunoprecipitation assay, these combined results suggest that IE1 inhibits or reverses HDAC-mediated repression of the infecting viral genomes, possibly by a process akin to activation of heterochromatin. We propose that even permissive cells can repress transcription of infecting viral genomes through repressors, including HDAC, Daxx, and PML, and the segregation of IE1 to ND10 that would inactivate those repressors. The virus can counter this repression by overexpressing IE1 when present in sufficient copy number, thus reducing the availability and effectiveness of these repressors.

scholarly journals Mouse Cytomegalovirus Early M112/113 Proteins Control the Repressive Effect of IE3 on the Major Immediate-Early Promoter

2005 ◽  
Vol 79 (1) ◽  
pp. 257-263 ◽  
Author(s):  
Qiyi Tang ◽  
Luge Li ◽  
Gerd G. Maul
Keyword(s):  
Feedback Mechanism ◽  
Immediate Early ◽  
Gene Products ◽  
Splice Form ◽  
Mouse Cytomegalovirus ◽  
Viral Genomes ◽  
Early Proteins ◽  
Repressive Effect ◽  
Reporter Assays ◽  
Major Immediate Early Promoter

ABSTRACT The mouse cytomegalovirus major immediate-early (IE) transcript is differentially spliced to produce two IE proteins: IE1, which functions partly to maintain its own promoter, the major IE promoter (MIEP), free from repression, and IE3, which functions partly as a repressor of MIEP. Paradoxically, the site where transcription of the viral genome occurs is also the site where the greatest amounts of IE3 accumulate. This raises the question of how the repression capabilities of IE3 are controlled so soon after infection. We detected IE3, an activator of early proteins, contemporaneously with gene products of the early M112/113 locus. Both IE3 and the early M112/113 gene products colocalize and coimmunoprecipitate. Protein interaction most likely occurs between IE3 and the 87-kDa splice form of M112/113, because only the 87-kDa component coimmunoprecipitated with IE3. The complex also includes PML. Transiently expressed M112/113 can form large domains alone, even in the absence of full viral genomes or PML. Coexpression of M112/113 products and IE3 results in segregation of IE3 into newly formed M112/113-based domains. Importantly, coexpression eliminates the IE3-based repressive effect on MIEP, as determined by MIEP-driven reporter assays. The consequence of segregating IE3 into the M112/113-containing prereplication domains appears to make IE3 unavailable for binding and repressing MIEP during the earliest stages of infection. These findings establish a new feedback mechanism between IE and early proteins, a new mechanism of promoter control via segregation of the repressor, and a new function for proteins from the M112/113 locus.

scholarly journals The Mouse Cytomegalovirus Immediate-Early 1 Gene Is Not Required for Establishment of Latency or for Reactivation in the Lungs

2009 ◽  
Vol 83 (9) ◽  
pp. 4030-4038 ◽  
Author(s):  
Andreas Busche ◽  
Anja Marquardt ◽  
Andre Bleich ◽  
Peter Ghazal ◽  
Ana Angulo ◽  
...  
Keyword(s):  
Latent Infection ◽  
Acute Infection ◽  
Lytic Replication ◽  
Immediate Early ◽  
Productive Infection ◽  
Viral Gene ◽  
Mouse Cytomegalovirus ◽  
Early Protein ◽  
Latently Infected

ABSTRACT The immediate-early protein IE1 of human and mouse cytomegalovirus (MCMV) is one of the first proteins expressed during the productive infection cycle and upon reactivation from latency. The CMV IE1 proteins have been found to inhibit histone deacetylases, suggesting a role in the epigenetic regulation of viral gene expression. Consequently, the IE1 protein is considered to have a profound effect on reactivation, because small amounts of IE1 may be decisive for the switch to lytic replication. Here we asked if an MCMV Δie1 mutant is able both to establish latency and to reactivate from the lungs of latently infected mice. Since the Δie1 mutant was known to be attenuated during acute infection, we first defined conditions that led to comparable levels of viral genomes during latent infection with mutant and wild-type (wt) MCMV. Viral genome copy numbers dropped considerably at the onset of the latent infection but then remained steady for both viruses even after several months. Reactivation of the Δie1 mutant and of wt MCMV from latency occurred with similar incidences in lung explant cultures at 4, 7, and 12 months postinfection. The increase in the frequency of a subset of MCMV-specific memory T cells, a possible indicator of frequent transcriptional reactivation events during latency, was in a comparable range for both viruses. Recurrence of the Δie1 virus infection in vivo could also be induced by hematoablative treatment of latently infected mice. We conclude that the ie1 gene is not essential for the establishment of latency or for the reactivation of MCMV.

scholarly journals Functional interaction of the human cytomegalovirus IE2 protein with histone deacetylase 2 in infected human fibroblasts

2007 ◽  
Vol 88 (12) ◽  
pp. 3214-3223 ◽  
Author(s):  
Jung-Jin Park ◽  
Young-Eui Kim ◽  
Hong Thanh Pham ◽  
Eui Tae Kim ◽  
Young-Hwa Chung ◽  
...  
Keyword(s):  
Histone Deacetylase ◽  
Human Cytomegalovirus ◽  
Trichostatin A ◽  
Human Fibroblasts ◽  
Productive Infection ◽  
Viral Polymerase ◽  
Histone Deacetylase 2 ◽  
Histone Deacetylase 1 ◽  
Repressive Effect ◽  
Infected Cells

In human cytomegalovirus (HCMV)-infected cells, the 86 kDa immediate-early (IE) 2 protein plays a key role in transactivating downstream viral genes. Recently, IE2 has been shown to interact with histone deacetylase 1 (HDAC1) and HDAC3. HDAC1 recruited by IE2 was required for IE2-mediated autorepression of the major IE (MIE) promoter, whereas IE2–HDAC3 interaction was suggested to relieve the repressive effect of HDAC3 on viral early promoters. However, whether IE2 indeed inhibits HDAC's deacetylation activity on viral promoters and interacts with other HDACs remains unclear. Here, we provide evidence that IE2 functionally interacts with HDAC2 and negates its repressive effect on the viral polymerase promoter. IE2 interacted with HDAC2 in both virus-infected cells and in vitro, and required the conserved C-terminal half for HDAC2 binding. The subcellular localization of HDAC2 was changed in virus-infected cells, showing colocalization with IE2 in viral transcription and replication sites. The overall HDAC2 protein levels and its deacetylation activity slightly increased during the late stages of infection and the IE2-associated deacetylation activity was still sensitive to an HDAC inhibitor, trichostatin A. In transfection assays, however, histone acetylation of the viral polymerase promoter was suppressed by HDAC2, and this was relieved by IE2 binding. Therefore, our data demonstrate that IE2 functionally interacts with HDAC2 and modulates its deacetylation activity on the viral polymerase promoter. Our results also support the idea that interactions of IE2 with several HDACs to modulate the host epigenetic regulation on viral MIE and early promoters are important events in the process of productive infection.

scholarly journals Herpes Simplex Virus ICP27 Is Required for Virus-Induced Stabilization of the ARE-Containing IEX-1 mRNA Encoded by the Human IER3 Gene

2006 ◽  
Vol 80 (19) ◽  
pp. 9720-9729 ◽  
Author(s):  
Jennifer A. Corcoran ◽  
Wei-Li Hsu ◽  
James R. Smiley
Keyword(s):  
Herpes Simplex Virus ◽  
Herpes Simplex ◽  
Mapk Pathway ◽  
Immediate Early ◽  
Productive Infection ◽  
Mrna Stabilization ◽  
Early Protein ◽  
Host Shutoff ◽  
Simplex Virus ◽  
Hsv 1

ABSTRACT Herpes simplex virus (HSV) stifles cellular gene expression during productive infection of permissive cells, thereby diminishing host responses to infection. Host shutoff is achieved largely through the complementary actions of two viral proteins, ICP27 and virion host shutoff (vhs), that inhibit cellular mRNA biogenesis and trigger global mRNA decay, respectively. Although most cellular mRNAs are thus depleted, some instead increase in abundance after infection; perhaps surprisingly, some of these contain AU-rich instability elements (AREs) in their 3′-untranslated regions. ARE-containing mRNAs normally undergo rapid decay; however, their stability can increase in response to signals such as cytokines and virus infection that activate the p38/MK2 mitogen-activated protein kinase (MAPK) pathway. We and others have shown that HSV infection stabilizes the ARE mRNA encoding the stress-inducible IEX-1 mRNA, and a previous report from another laboratory has suggested vhs is responsible for this effect. However, we now report that ICP27 is essential for IEX-1 mRNA stabilization whereas vhs plays little if any role. A recent report has documented that ICP27 activates the p38 MAPK pathway, and we detected a strong correlation between this activity and stabilization of IEX-1 mRNA by using a panel of HSV type 1 (HSV-1) isolates bearing an array of previously characterized ICP27 mutations. Furthermore, IEX-1 mRNA stabilization was abrogated by the p38 inhibitor SB203580. Taken together, these data indicate that the HSV-1 immediate-early protein ICP27 alters turnover of the ARE-containing message IEX-1 by activating p38. As many ARE mRNAs encode proinflammatory cytokines or other immediate-early response proteins, some of which may limit viral replication, it will be of great interest to determine if ICP27 mediates stabilization of many or all ARE-containing mRNAs.

scholarly journals Enrichment of Immediate-Early 1 (m123/pp89) Peptide-Specific CD8 T Cells in a Pulmonary CD62Llo Memory-Effector Cell Pool during Latent Murine Cytomegalovirus Infection of the Lungs

2000 ◽  
Vol 74 (24) ◽  
pp. 11495-11503 ◽  
Author(s):  
Rafaela Holtappels ◽  
Marcus-Folker Pahl-Seibert ◽  
Doris Thomas ◽  
Matthias J. Reddehase
Keyword(s):  
T Cells ◽  
T Cell Activation ◽  
Cd8 T Cells ◽  
Immediate Early ◽  
Productive Infection ◽  
Murine Cytomegalovirus ◽  
Antigenic Peptides ◽  
Memory Cells ◽  
Effector Cells ◽  
Early Protein

ABSTRACT Interstitial cytomegalovirus (CMV) pneumonia is a clinically relevant complication in recipients of bone marrow transplantation (BMT). Recent data for a model of experimental syngeneic BMT and concomitant infection of BALB/c mice with murine CMV (mCMV) have documented the persistence of tissue-resident CD8 T cells after clearance of productive infection of the lungs (J. Podlech, R. Holtappels, M.-F. Pahl-Seibert, H.-P. Steffens, and M. J. Reddehase, J. Virol. 74:7496–7507, 2000). It was proposed that these cells represent antiviral “standby” memory cells whose functional role might be to help prevent reactivation of latent virus. The pool of pulmonary CD8 T cells was composed of two subsets defined by the T-cell activation marker L-selectin (CD62L): a CD62Lhi subset of quiescent memory cells, and a CD62Llo subset of recently resensitized memory-effector cells. In this study, we have continued this line of investigation by quantitating CD8 T cells specific for the three currently published antigenic peptides of mCMV: peptide YPHFMPTNL processed from the immediate-early protein IE1 (pp89), and peptides YGPSLYRRF and AYAGLFTPL, derived from the early proteins m04 (gp34) and M84 (p65), respectively. IE1-specific CD8 T cells dominated in acute-phase pulmonary infiltrates and were selectively enriched in latently infected lungs. Notably, most IE1-specific CD8 T cells were found to belong to the CD62Llo subset representing memory-effector cells. This finding is in accordance with the interpretation that IE1-specific CD8 T cells are frequently resensitized during latent infection of the lungs and may thus be involved in the maintenance of mCMV latency.

scholarly journals The Human Cytomegalovirus 86-Kilodalton Major Immediate-Early Protein Interacts Physically and Functionally with Histone Acetyltransferase P/CAF

2000 ◽  
Vol 74 (16) ◽  
pp. 7230-7237 ◽  
Author(s):  
L. A. Bryant ◽  
P. Mixon ◽  
M. Davidson ◽  
A. J. Bannister ◽  
T. Kouzarides ◽  
...  
Keyword(s):  
Gene Expression ◽  
Human Cytomegalovirus ◽  
Histone Acetyltransferase ◽  
Early Gene ◽  
Immediate Early ◽  
Productive Infection ◽  
Early Protein ◽  
Cellular Genes ◽  
Immediate Early Proteins ◽  
Target Promoters

ABSTRACT The major immediate-early proteins of human cytomegalovirus (HCMV) play a pivotal role in controlling viral and cellular gene expression during productive infection. As well as negatively autoregulating its own promoter, the HCMV 86-kDa major immediate early protein (IE86) activates viral early gene expression and is known to be a promiscuous transcriptional regulator of cellular genes. IE86 appears to act as a multimodal transcription factor. It is able to bind directly to target promoters to activate transcription but is also able to bridge between upstream binding factors such as CREB/ATF and the basal transcription complex as well as interacting directly with general transcription factors such as TATA-binding protein and TFIIB. We now show that IE86 is also able to interact directly with histone acetyltransferases during infection. At least one of these factors is the histone acetyltransferase CBP-associated factor (P/CAF). Furthermore, we show that this interaction results in synergistic transactivation by IE86 of IE86-responsive promoters. Recruitment of such chromatin-remodeling factors to target promoters by IE86 may help explain the ability of this viral protein to act as a promiscuous transactivator of cellular genes.

scholarly journals The herpes simplex virus immediate-early protein ICP27 stimulates the transcription of cellular Alu repeated sequences by increasing the activity of transcription factor TFIIIC

1992 ◽  
Vol 284 (3) ◽  
pp. 667-673 ◽  
Author(s):  
K L Jang ◽  
D S Latchman
Keyword(s):  
Transcription Factor ◽  
Herpes Simplex Virus ◽  
Herpes Simplex ◽  
Immediate Early ◽  
Cellular Transcription Factor ◽  
Early Protein ◽  
Simplex Virus ◽  
Cellular Transcription ◽  
Increased Activity ◽  
In Cells

Infection with herpes simplex virus (HSV) results in an increase in the transcription of the endogenous Alu repeated sequence by RNA polymerase III. This effect is also observed in uninfected cells stably transformed with a plasmid expressing the HSV immediate-early protein ICP27 or in cells transfected with the gene encoding this protein. Both uninfected cells expressing ICP27 and cells infected with virus producing functional ICP27 display increased activity of the cellular transcription factor TFIIIC when compared with untreated cells. This increase is not observed, however, in cells infected with a mutant strain of virus which does not produce ICP27. Hence ICP27 induces elevated Alu transcription by activating transcription factor TFIIIC, which is the limiting factor for such transcription. This is the first report of increased activity of a cellular transcription factor during HSV infection, when most cellular gene activity is inhibited.

scholarly journals Bovine herpesvirus 1 immediate-early protein (bICP0) interacts with the histone acetyltransferase p300, which stimulates productive infection and gC promoter activity

2006 ◽  
Vol 87 (7) ◽  
pp. 1843-1851 ◽  
Author(s):  
Yange Zhang ◽  
Yunquan Jiang ◽  
Vicki Geiser ◽  
Joe Zhou ◽  
Clinton Jones
Keyword(s):  
Histone Acetyltransferase ◽  
Ring Finger ◽  
Bovine Herpesvirus ◽  
Immediate Early ◽  
Productive Infection ◽  
Dominant Negative Mutant ◽  
Bovine Herpesvirus 1 ◽  
Early Protein ◽  
Herpesvirus 1 ◽  
Acetyltransferase P300

The immediate-early protein, bICP0, of Bovine herpesvirus 1 (BHV-1) transactivates viral promoters and stimulates productive infection. bICP0 is expressed constitutively during productive infection, as its gene contains an immediate-early and an early promoter. Like other ICP0 homologues encoded by members of the subfamily Alphaherpesvirinae, bICP0 contains a zinc RING finger located near its N terminus. Mutations that disrupt the bICP0 zinc RING finger impair its ability to activate transcription, stimulate productive infection, inhibit interferon-dependent transcription in certain cell types and regulate subnuclear localization. bICP0 also interacts with a cellular chromatin-remodelling enzyme, histone deacetylase 1 (HDAC1), and can relieve HDAC1-mediated transcriptional repression, suggesting that bICP0 inhibits silencing of the viral genome. In this study, it was shown that bICP0 interacted with the histone acetyltransferase p300 during productive infection and in transiently transfected cells. In addition, p300 enhanced BHV-1 productive infection and transactivated a late viral promoter (gC). In contrast, a CH3-domain deletion mutant of p300, which is a dominant-negative mutant, did not activate the gC promoter. bICP0 and p300 cooperated to activate the gC promoter, suggesting that there is a synergistic effect on promoter activation. As p300 can activate certain antiviral signalling pathways (for example, interferon), it was hypothesized that interactions between p300 and bICP0 may dampen the antiviral response following infection.

scholarly journals Phosphorylation of the Nuclear Form of Varicella-Zoster Virus Immediate-Early Protein 63 by Casein Kinase II at Serine 186

2009 ◽  
Vol 83 (23) ◽  
pp. 12094-12100 ◽  
Author(s):  
Niklaus H. Mueller ◽  
Laurie L. Graf ◽  
David Orlicky ◽  
Don Gilden ◽  
Randall J. Cohrs
Keyword(s):  
Monoclonal Antibody ◽  
Varicella Zoster Virus ◽  
Casein Kinase Ii ◽  
Casein Kinase ◽  
Antibody Binding ◽  
Immediate Early ◽  
Productive Infection ◽  
Varicella Zoster ◽  
Recombinant Monoclonal Antibody ◽  
Early Protein

ABSTRACT Varicella-zoster virus (VZV) open reading frame (ORF) 63 is abundantly transcribed in latently infected human ganglia and encodes a 278-amino-acid protein, IE63, with immediate-early kinetics. IE63 is expressed in the cytoplasm of neurons during VZV latency and in both the cytoplasm and the nucleus during productive infection; however, the mechanism(s) involved in IE63 nuclear import and retention has remained unclear. We constructed and identified a recombinant monoclonal antibody to detect a posttranslationally modified form of IE63. Analysis of a series of IE63 truncation and substitution mutants showed that amino acids 186 to 195 are required for antibody binding. Synthetic peptides corresponding to this region identified IE63 S186 as a target for casein kinase II phosphorylation. In addition, acidic charges supplied by E194 and E195 were required for antibody binding. Immunofluorescence analysis of VZV-infected MeWo cells using the recombinant monoclonal antibody detected IE63 exclusively in the nuclei of infected cells, indicating that casein kinase II phosphorylation of S186 occurs in the nucleus and possibly identifying an initial molecular event operative in VZV reactivation.

scholarly journals Reactivation of the Human Cytomegalovirus Major Immediate-Early Regulatory Region and Viral Replication in Embryonal NTera2 Cells: Role of Trichostatin A, Retinoic Acid, and Deletion of the 21-Base-Pair Repeats and Modulator

2001 ◽  
Vol 75 (4) ◽  
pp. 1581-1593 ◽  
Author(s):  
Jeffery L. Meier
Keyword(s):  
Retinoic Acid ◽  
Viral Replication ◽  
Histone Deacetylase ◽  
Human Cytomegalovirus ◽  
Trichostatin A ◽  
Regulatory Region ◽  
Immediate Early ◽  
Unique Region ◽  
Viral Genomes ◽  
Nt2 Cells

ABSTRACT Inactivity of the human cytomegalovirus (HCMV) major immediate-early regulatory region (MIERR), which is composed of promoter, enhancer, unique region, and modulator, is linked to lack of HCMV replication in latently infected cells and in other nonpermissive cell types, including human embryonal NTera2 carcinoma (NT2) cells. I refined the embryonal NT2 cell model to enable characterization of the unknown mechanistic basis for silencing of HCMV MIERR-dependent transcription and viral replication in nonpermissive cells. These infected NT2 cells contain nonreplicating viral genomes with electrophoretic mobility equivalent to a supercoiled, bacterial artificial chromosome of comparable molecular weight. MIERR-dependent transcription is minimal to negligible. Increasing the availability of positive-acting transcription factors by retinoic acid (RA) treatment after infection is largely insufficient in reactivating the MIERR. In contrast, trichostatin A (TSA), a histone deacetylase inhibitor, reactivates MIERR-dependent transcription. Contrary to prior findings produced from transfected MIERR segments, deletion of the 21-bp repeats and modulator from the MIERR in the viral genome does not relieve MIERR silencing. To demonstrate that MIERR silencing likely results from enhancer inactivity, I examined an HCMV with a heterologous MIERR promoter that is enhancer dependent but exempt from IE2 p86-mediated negative autoregulation. This heterologous promoter, like its neighboring native MIERR promoter, exhibits immediate-early transcriptional kinetics in fibroblasts. In embryonal NT2 cells, the heterologous MIERR promoter is transcriptionally inactive. This silence is relieved by TSA but not by RA. Remarkably, TSA-induced reactivation of MIERR-dependent transcription from quiescent viral genomes is followed by release of infectious virus. I conclude that a mechanism of active repression imposes a block to MIERR-dependent transcription and viral replication in embryonal NT2 cells. Because TSA overcomes the block, viral gene silencing may involve histone deacetylase-based modification of viral chromatin, which might account for the covalently closed circular conformation of quiescent HCMV genomes.

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