The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Shannon C Kenney - One of the best experts on this subject based on the ideXlab platform.
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small molecule perturbation of the cand1 cullin1 ubiquitin cycle stabilizes p53 and triggers epstein barr virus reactivation
PLOS Pathogens, 2017Co-Authors: Nadezhda Tikhmyanova, Shannon C Kenney, Steve Tutton, Kayla A Martin, Fang Lu, Andrew V Kossenkov, Nicholas Paparoidamis, Joseph M Salvino, Paul M LiebermanAbstract:The chemical probe C60 efficiently triggers Epstein-Barr Virus (EBV) reactivation from latency through an unknown mechanism. Here, we identify the Cullin exchange factor CAND1 as a biochemical target of C60. We also identified CAND1 in an shRNA library screen for EBV lytic reactivation. Gene expression profiling revealed that C60 activates the p53 pathway and Protein analysis revealed a strong stabilization and S15 phosphorylation of p53. C60 reduced Cullin1 association with CAND1 and led to a global accumulation of ubiquitylated substrates. C60 also stabilized the EBV Immediate Early Protein ZTA through a Cullin-CAND1-interaction motif in the ZTA transcription activation domain. We propose that C60 perturbs the normal interaction and function of CAND1 with Cullins to promote the stabilization of substrates like ZTA and p53, leading to EBV reactivation from latency. Understanding the mechanism of action of C60 may provide new approaches for treatment of EBV associated tumors, as well as new tools to stabilize p53.
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the b cell specific transcription factor and master regulator pax5 promotes epstein barr virus latency by negatively regulating the viral Immediate Early Protein bzlf1
Journal of Virology, 2013Co-Authors: Ryan M Raver, Amanda R Panfil, Stacy R Hagemeier, Shannon C KenneyAbstract:The latent-to-lytic switch of Epstein-Barr virus (EBV) is mediated by the Immediate Early Protein BZLF1 (Z). However, the cellular factors regulating this process remain incompletely characterized. In this report, we show that the B-cell-specific transcription factor Pax5 helps to promote viral latency in B cells by blocking Z function. Although Z was previously shown to directly interact with Pax5 and inhibit its activity, the effect of Pax5 on Z function has not been investigated. Here, we demonstrate that Pax5 inhibits Z-mediated lytic viral gene expression and the release of infectious viral particles in latently infected epithelial cell lines. Conversely, we found that shRNA-mediated knockdown of endogenous Pax5 in a Burkitt lymphoma B-cell line leads to viral reactivation. Furthermore, we show that Pax5 reduces Z activation of Early lytic viral promoters in reporter gene assays and inhibits Z binding to lytic viral promoters in vivo. We confirm that Pax5 and Z directly interact and show that this interaction requires the carboxy-terminal DNA-binding/dimerization domain of Z and the amino-terminal DNA-binding domain of Pax5. A Pax5 DNA-binding mutant (V26G/P80R) that interacts with Z retains the ability to inhibit Z function, whereas a Pax5 mutant (Δ106-110) that is deficient for interaction with Z does not inhibit Z-mediated lytic viral reactivation. Since the B-cell-specific transcription factor Oct-2 also directly interacts with Z and inhibits its function, these results suggest that EBV uses multiple redundant mechanisms to establish and maintain viral latency in B cells.
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the b cell specific transcription factor and master regulator pax5 promotes epstein barr virus latency by negatively regulating the viral Immediate Early Protein bzlf1
Journal of Virology, 2013Co-Authors: Ryan M Raver, Amanda R Panfil, Stacy R Hagemeier, Shannon C KenneyAbstract:The latent-to-lytic switch of Epstein-Barr virus (EBV) is mediated by the Immediate Early Protein BZLF1 (Z). However, the cellular factors regulating this process remain incompletely characterized. In this report, we show that the B-cell-specific transcription factor Pax5 helps to promote viral latency in B cells by blocking Z function. Although Z was previously shown to directly interact with Pax5 and inhibit its activity, the effect of Pax5 on Z function has not been investigated. Here, we demonstrate that Pax5 inhibits Z-mediated lytic viral gene expression and the release of infectious viral particles in latently infected epithelial cell lines. Conversely, we found that shRNA-mediated knockdown of endogenous Pax5 in a Burkitt lymphoma B-cell line leads to viral reactivation. Furthermore, we show that Pax5 reduces Z activation of Early lytic viral promoters in reporter gene assays and inhibits Z binding to lytic viral promoters in vivo. We confirm that Pax5 and Z directly interact and show that this interaction requires the carboxy-terminal DNA-binding/dimerization domain of Z and the amino-terminal DNA-binding domain of Pax5. A Pax5 DNA-binding mutant (V26G/P80R) that interacts with Z retains the ability to inhibit Z function, whereas a Pax5 mutant (Δ106-110) that is deficient for interaction with Z does not inhibit Z-mediated lytic viral reactivation. Since the B-cell-specific transcription factor Oct-2 also directly interacts with Z and inhibits its function, these results suggest that EBV uses multiple redundant mechanisms to establish and maintain viral latency in B cells.
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the b cell specific transcription factor oct 2 promotes epstein barr virus latency by inhibiting the viral Immediate Early Protein bzlf1
PLOS Pathogens, 2012Co-Authors: Amanda R Robinson, Swee Sen Kwek, Shannon C KenneyAbstract:The Epstein-Barr virus (EBV) latent-lytic switch is mediated by the BZLF1 Immediate-Early Protein. EBV is normally latent in memory B cells, but cellular factors which promote viral latency specifically in B cells have not been identified. In this report, we demonstrate that the B-cell specific transcription factor, Oct-2, inhibits the function of the viral Immediate-Early Protein, BZLF1, and prevents lytic viral reactivation. Co-transfected Oct-2 reduces the ability of BZLF1 to activate lytic gene expression in two different latently infected nasopharyngeal carcinoma cell lines. Furthermore, Oct-2 inhibits BZLF1 activation of lytic EBV promoters in reporter gene assays, and attenuates BZLF1 binding to lytic viral promoters in vivo. Oct-2 interacts directly with BZLF1, and this interaction requires the DNA-binding/dimerization domain of BZLF1 and the POU domain of Oct-2. An Oct-2 mutant (Δ262–302) deficient for interaction with BZLF1 is unable to inhibit BZLF1-mediated lytic reactivation. However, an Oct-2 mutant defective for DNA-binding (Q221A) retains the ability to inhibit BZLF1 transcriptional effects and DNA-binding. Importantly, shRNA-mediated knockdown of endogenous Oct-2 expression in several EBV-positive Burkitt lymphoma and lymphoblastoid cell lines increases the level of lytic EBV gene expression, while decreasing EBNA1 expression. Moreover, treatments which induce EBV lytic reactivation, such as anti-IgG cross-linking and chemical inducers, also decrease the level of Oct-2 Protein expression at the transcriptional level. We conclude that Oct-2 potentiates establishment of EBV latency in B cells.
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epstein barr virus lytic infection induces retinoic acid responsive genes through induction of a retinol metabolizing enzyme dhrs9
Journal of Biological Chemistry, 2007Co-Authors: Richard J Jones, Sarah J Dickerson, Prassana M Bhende, Henri Jacques Delecluse, Shannon C KenneyAbstract:Lytic Epstein-Barr virus (EBV) replication occurs in differentiated, but not undifferentiated, epithelial cells. Retinoic acid (RA) induces epithelial cell differentiation. The conversion of retinol into its active form, retinoic acid, requires retinol dehydrogenase enzymes. Here we show that AGS gastric carcinoma cells containing the lytic form of EBV infection have enhanced expression of a gene (DHRS9) encoding an enzyme that mediates conversion of retinol into RA. DHRS9 expression is also increased following induction of lytic viral infection in EBV-positive Burkitt lymphoma cells. We demonstrate that the EBV Immediate-Early Protein, BZLF1, activates the DHRS9 promoter through a direct DNA binding mechanism. Furthermore, BZLF1 expression in AGS cells is sufficient to activate DHRS9 gene expression and increases the ability of retinol to induce the RA-responsive gene, CYP26A1. Production of RA during the lytic form of EBV infection may enhance viral replication by promoting keratinocyte differentiation.
Roger D Everett - One of the best experts on this subject based on the ideXlab platform.
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herpes simplex virus type 1 Immediate Early Protein icp0 and its isolated ring finger domain act as ubiquitin e3 ligases in vitro
Journal of Virology, 2002Co-Authors: Chris Boutell, Seth Sadis, Roger D EverettAbstract:Proteasome-dependent degradation of ubiquitinated Proteins plays a key role in many important cellular processes. Ubiquitination requires the E1 ubiquitin activating enzyme, an E2 ubiquitin conjugating enzyme, and frequently a substrate-specific ubiquitin Protein ligase (E3). One class of E3 ubiquitin ligases has been shown to contain a common zinc-binding RING finger motif. We have previously shown that herpes simplex virus type 1 ICP0, itself a RING finger Protein, induces the proteasome-dependent degradation of several cellular Proteins and induces the accumulation of colocalizing conjugated ubiquitin in vivo. We now report that both full-length ICP0 and its isolated RING finger domain induce the accumulation of polyubiquitin chains in vitro in the presence of E1 and the E2 enzymes UbcH5a and UbcH6. Mutations within the RING finger region that abolish the in vitro ubiquitination activity also cause severe reductions in ICP0 activity in other assays. We conclude that ICP0 has the potential to act as an E3 ubiquitin ligase during viral infection and to target specific cellular Proteins for destruction by the 26S proteasome.
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alphaherpesvirus Proteins related to herpes simplex virus type 1 icp0 induce the formation of colocalizing conjugated ubiquitin
Journal of Virology, 2001Co-Authors: Jane Parkinson, Roger D EverettAbstract:Herpes simplex virus type 1 Immediate Early Protein ICP0 influences virus infection by inducing the degradation of specific cellular Proteins via a mechanism requiring its RING finger and the ubiquitin-proteasome pathway. Many RING finger Proteins, by virtue of their RING finger domain, interact with E2 ubiquitin-conjugating enzymes and act as a component of an E3 ubiquitin ligase. We have recently shown that ICP0 induces the accumulation of colocalizing, conjugated ubiquitin, suggesting that ICP0 can act as or contribute to an E3 ubiquitin ligase. In this report we demonstrate that the ICP0-related RING finger Proteins encoded by other alphaherpesviruses also induce colocalizing, conjugated ubiquitin, thereby suggesting that they act by similar biochemical mechanisms.
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herpes simplex virus type 1 Immediate Early Protein vmw110 inhibits progression of cells through mitosis and from g 1 into s phase of the cell cycle
Journal of Virology, 1999Co-Authors: Patrick Lomonte, Roger D EverettAbstract:Herpes simplex virus type 1 (HSV-1) Immediate-Early Protein Vmw110 stimulates the onset of virus infection in a multiplicity-dependent manner and is required for efficient reactivation from latency. Recent work has shown that Vmw110 is able to interact with or modify the stability of several cellular Proteins. In this report we analyze the ability of Vmw110 to inhibit the progression of cells through the cell cycle. We show by fluorescence-activated cell sorter and/or confocal microscopy analysis that an enhanced green fluorescent Protein-tagged Vmw110 possesses the abilities both to prevent transfected cells moving from G(1) into S phase and to block infected cells at an unusual stage of mitosis defined as pseudo-prometaphase. The latter property correlates with the Vmw110-induced proteasome-dependent degradation of CENP-C, a centromeric Protein component of the inner plate of human kinetochores. We also show that whereas Vmw110 is not the only viral product implicated in the block of infected cells at the G(1)/S border, the mitotic block is a specific property of Vmw110 and more particularly of its RING finger domain. These data explain the toxicity of Vmw110 when expressed alone in transfected cells and provide an explanation for the remaining toxicity of replication-defective mutants of HSV-1 expressing Vmw110. In addition to contributing to our understanding of the effects of Vmw110 on the cell, our results demonstrate that Vmw110 expression is incompatible with the proliferation of a dividing cell population. This factor is of obvious importance to the design of gene therapy vectors based on HSV-1.
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specific destruction of kinetochore Protein cenp c and disruption of cell division by herpes simplex virus Immediate Early Protein vmw110
The EMBO Journal, 1999Co-Authors: Roger D Everett, William C Earnshaw, John Findlay, Patrick LomonteAbstract:Examination of cells at the Early stages of herpes simplex virus type 1 infection revealed that the viral Immediate-Early Protein Vmw110 (also known as ICP0) formed discrete punctate accumulations associated with centromeres in both mitotic and interphase cells. The RING finger domain of Vmw110 (but not the C-terminal region) was essential for its localization at centromeres, thus distinguishing the Vmw110 sequences required for centromere association from those required for its localization at other discrete nuclear structures known as ND10, promyelocytic leukaemia (PML) bodies or PODs. We have shown recently that Vmw110 can induce the proteasome-dependent loss of several cellular Proteins, including a number of probable SUMO-1-conjugated isoforms of PML, and this results in the disruption of ND10. In this study, we found some striking similarities between the interactions of Vmw110 with ND10 and centromeres. Specifically, centromeric Protein CENP-C was lost from centromeres during virus infection in a Vmw110- and proteasome-dependent manner, causing substantial ultrastructural changes in the kinetochore. In consequence, dividing cells either became stalled in mitosis or underwent an unusual cytokinesis resulting in daughter cells with many micronuclei. These results emphasize the importance of CENP-C for mitotic progression and suggest that Vmw110 may be interfering with biochemical mechanisms which are relevant to both centromeres and ND10.
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herpes simplex virus type 1 Immediate Early Protein vmw110 induces the proteasome dependent degradation of the catalytic subunit of dna dependent Protein kinase
Journal of Virology, 1999Co-Authors: Jane Parkinson, Susan P Leesmiller, Roger D EverettAbstract:Herpes simplex virus type 1 (HSV-1) infection causes the active degradation of the catalytic subunit of DNA-dependent Protein kinase (DNA-PKcs), and this process is reliant on the expression of the HSV-1 Immediate-Early Protein Vmw110. In this study we investigated in more detail the mechanism by which the degradation occurs, the domains of Vmw110 which are required, and whether Vmw110 is by itself sufficient for the effect. We found that proteasome inhibitors prevented the degradation of DNA-PKcs, indicating the involvement of a proteasome pathway. Furthermore, the continued activity of DNA-PK during infection in the presence of these inhibitors indicated that Vmw110 does not directly alter the enzyme activity of DNA-PKcs prior to its degradation in a normal infection. Indeed, Vmw110 was found to bind to neither the catalytic nor Ku subunits of DNA-PK. Using mutant Vmw110 viruses we show that the RING finger domain of Vmw110 is essential for the induced degradation of DNA-PKcs but that the ability of Vmw110 to bind to a cellular ubiquitin-specific protease (HAUSP) is not required. When expressed in the absence of other viral Proteins, Vmw110 was sufficient to cause the degradation of DNA-PKcs, indicating that the effect on the stability of DNA-PKcs was a direct consequence of Vmw110 activity and not an indirect Vmw110-dependent effect of virus infection. Finally, the Vmw110-induced degradation of DNA-PKcs and loss in DNA-PK activity appears to be beneficial to HSV-1 infection, as virus replication was more efficient in cells lacking DNA-PKcs, especially at low multiplicities of infection.
Ann M. Arvin - One of the best experts on this subject based on the ideXlab platform.
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Recognition of the Latency-Associated Immediate Early Protein IE63 of Varicella-Zoster Virus by Human Memory
2016Co-Authors: T Lymphocytes, Bernard Rentier, Catherine Sadzot-delvaux, Paul R. Kinchington, Serge Debrus, Ann M. ArvinAbstract:Varicella-zoster virus (VZV) is a human alphaherpesvirus that establishes latency in sensory ganglia. latency is characterized by the abundant expression of the Immediate Early Protein 63 (IE63), whereas other viral Proteins have not yet been detected during the quiescent phase of VZV infection. The IE63 Protein is a component of the virion and is expressed very Early in the infectious cycle. The IE63 Protein is also expressed in skin during episodes of varicella and herpes zoster. We have evaluated the cell-mediated immune response against IE63 in naturally immune adults with a history of chickenpox, by T lymphoprolif-eration and cytotoxicity assays. Among donors who had T cell proliferation to unfractionated VZV Ags from infected cell extract, 59 % had T cell recognition of purified IE63. The CTl response to IE63 was equivalent to CTL recognition of IE62, the major tegument component of VZV whose immunogenicity has been previously described. IgC Abs against IE63 were detected in serum from healthy immune adults. These results indicate that IE63 is an important target of immunity to VZV. T cell recognition of 1E63 is likely to be involved in controlling VZV reactivation from latency. The Journal of Immunology, 1997, 159: 2802-2806. V aricella-zoster virus (VZV) ’ is a human herpesvirus that causes varicella (chickenpox) and herpes zoster (shin- gles) separated by an extended period of latency (1). After the primary infection, VZV reaches the sensory ganglia and persists for the life of the host. Although several regions of the viral genome are transcribed during latency (2, 3), the product o
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mutational analysis of varicella zoster virus vzv Immediate Early Protein ie62 subdomains and their importance in viral replication
Virology, 2016Co-Authors: Mohamed I Khalil, Marvin Sommer, Xibing Che, J Hay, Phillip Sung, Ann M. ArvinAbstract:VZV IE62 is an essential, Immediate-Early, tegument Protein and consists of five domains. We generated recombinant viruses carrying mutations in the first three IE62 domains and tested their influence on VZV replication kinetics. The mutations in domain I did not affect replication kinetics while domain II mutations, disrupting the DNA binding and dimerization domain (DBD), were lethal for VZV replication. Mutations in domain III of the nuclear localization signal (NLS) and the two phosphorylation sites S686A/S722A resulted in slower growth in Early and late infection respectively and were associated with IE62 accumulation in the cytoplasm and nucleus respectively. This study mapped the functional domains of IE62 in context of viral infection, indicating that DNA binding and dimerization domain is essential for VZV replication. In addition, the correct localization of IE62, whether nuclear or cytoplasmic, at different points in the viral life cycle, is important for normal progression of VZV replication.
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varicella zoster virus Immediate Early Protein 62 blocks interferon regulatory factor 3 irf3 phosphorylation at key serine residues a novel mechanism of irf3 inhibition among herpesviruses
Journal of Virology, 2010Co-Authors: Nandini Sen, William T Ruyechan, Marvin Sommer, Xibing Che, Kris White, Ann M. ArvinAbstract:Varicella-zoster virus (VZV) is an alphaherpesvirus that is restricted to humans. VZV infection of differentiated cells within the host and establishment of latency likely require evasion of innate immunity and limited secretion of antiviral cytokines. Since interferons (IFNs) severely limit VZV replication, we examined the ability of VZV to modulate the induction of the type I IFN response in primary human embryonic lung fibroblasts (HELF). IFN-β production was not detected, and transcription of two interferon response factor 3 (IRF3)-dependent interferon-stimulated genes (ISGs), ISG54 and ISG56, in response to poly(I:C) stimulation was downregulated in VZV-infected HELF. Inhibition of IRF3 function did not require VZV replication; the viral Immediate-Early Protein 62 (IE62) alone was sufficient to produce this effect. IE62 blocked TBK1-mediated IFN-β secretion and IRF3 function, as shown in an IFN-stimulated response element (ISRE)-luciferase reporter assay. However, IRF3 function was preserved if constitutively active IRF3 (IRF3-5D) was expressed in VZV-infected or IE62-transfected cells, indicating that VZV interferes with IRF3 phosphorylation. IE62-mediated inhibition was mapped to blocking phosphorylation of at least three serine residues on IRF3. However, IE62 binding to TBK1 or IRF3 was not detected and IE62 did not perturb TBK1-IRF3 complex formation. IE62-mediated inhibition of IRF3 function was maintained even if IE62 transactivator activity was disrupted. Thus, IE62 has two critical but discrete roles following VZV entry: to induce expression of VZV genes and to disarm the IFN-dependent antiviral defense through a novel mechanism that prevents IRF3 phosphorylation.
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identification of cd8 t cell epitopes in the Immediate Early 62 Protein ie62 of varicella zoster virus and evaluation of frequency of cd8 t cell response to ie62 by use of ie62 peptides after varicella vaccination
The Journal of Infectious Diseases, 2003Co-Authors: Christian R Frey, Margaret Sharp, Andrew S Min, Scott D Schmid, Vladimir N Loparev, Ann M. ArvinAbstract:Varicella-zoster virus (VZV) causes varicella, establishes neuronal latency, and can reactivate, resulting in herpes zoster. VZV-specific T cells are important for controlling infection. VZV Immediate Early Protein 62 (IE62) is recognized by cytotoxic T cells from immune individuals, but no CD8(+) T cell epitopes have been defined for any VZV Protein. CD8(+) T cell frequencies were assessed by cytokine flow cytometry (CFC), by use of synthetic-peptide pools corresponding to the IE62 sequence. IE62 peptide-specific CD8(+) T cells were below the threshold of detection, by direct CFC of either whole blood or peripheral blood mononuclear cells (PBMCs). Activated CD8(+)CD69(+) T cells that produced interferon-gamma were detectable after in vitro restimulation of PBMCs, and restricted epitopes were identified for HLA-A*0201-positive subjects. Varicella vaccination of 3 VZV-immune subjects was associated with increases in IE62 peptide-specific CD8(+) T cells, a finding indicating that in vivo re-exposure boosts memory immunity to this important viral Protein.
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the varicella zoster virus Immediate Early Protein ie62 is a major component of virus particles
Journal of Virology, 1992Co-Authors: P R Kinchington, William T Ruyechan, Ann M. Arvin, J K Hougland, J HayAbstract:Varicella-zoster virus (VZV) open reading frame (ORF) 62 potentially encodes a Protein with considerable amino acid homology to the herpes simplex virus (HSV) Immediate-Early regulatory polypeptide ICP4 (or IE3). To identify and characterize its Protein product(s) (IE62), we used a rabbit antiserum prepared against a synthetic peptide corresponding to the C-terminal 13 amino acids of the predicted Protein. This antiserum reacted with phosphorylated polypeptides of 175 to 180 kDa that were made in VZV-infected cells and in cells infected with a vaccinia virus recombinant expressing IE62, but not in control-infected cells, confirming its specificity and reactivity to the IE62 Protein. The antiserum recognized a 175-kDa polypeptide in purified virions that comigrated with a major structural Protein. Comparison of this reactivity with that of an antipeptide antiserum directed against the VZV ORF 10 product (homologous to the HSV major structural Protein VP16) indicates similar levels of ORF 62 and ORF 10 polypeptides in VZV virions. In contrast, antipeptide antiserum directed against the VZV ORF 29 product, the homolog of the HSV major DNA-binding Protein, failed to recognize any Protein in our virion preparations. Treatment of virions with detergents that disrupt the virion envelope did not dissociate IE62 from the nucleocapsid-tegument structure of the virion. Differential sensitivity of VZV virion IE62 to trypsin digestion in the presence or absence of Triton X-100 indicates that IE62 is protected from trypsin degradation by the virus envelope; since it is not a nucleocapsid Protein, we conclude that it is part of the tegument. Finally, we show that the virion 175-kDa Protein either can autophosphorylate or is a major substrate in vitro for virion-associated Protein kinase activity.
Stephen A Rice - One of the best experts on this subject based on the ideXlab platform.
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herpes simplex virus type 1 Immediate Early Protein icp22 is required for vice domain formation during productive viral infection
Journal of Virology, 2010Co-Authors: Thomas W Bastian, Christine M. Livingston, Sandra K Weller, Stephen A RiceAbstract:During productive infection, herpes simplex virus type 1 (HSV-1) induces the formation of discrete nuclear foci containing cellular chaperone Proteins, proteasomal components, and ubiquitinated Proteins. These structures are known as VICE domains and are hypothesized to play an important role in Protein turnover and nuclear remodeling in HSV-1-infected cells. Here we show that VICE domain formation in Vero and other cells requires the HSV-1 Immediate-Early Protein ICP22. Since ICP22 null mutants replicate efficiently in Vero cells despite being unable to induce VICE domain formation, it can be concluded that VICE domain formation is not essential for HSV-1 productive infection. However, our findings do not exclude the possibility that VICE domain formation is required for viral replication in cells that are nonpermissive for ICP22 mutants. Our studies also show that ICP22 itself localizes to VICE domains, suggesting that it could play a role in forming these structures. Consistent with this, we found that ICP22 expression in transfected cells is sufficient to reorganize the VICE domain component Hsc70 into nuclear inclusion bodies that resemble VICE domains. An N-terminal segment of ICP22, corresponding to residues 1 to 146, is critical for VICE domain formation in infected cells and Hsc70 reorganization in transfected cells. We previously found that this portion of the Protein is dispensable for ICP22's effects on RNA polymerase II phosphorylation. Thus, ICP22 mediates two distinct regulatory activities that both modify important components of the host cell nucleus.
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herpes simplex virus type 1 Immediate Early Protein icp27 is required for efficient incorporation of icp0 and icp4 into virions
Journal of Virology, 2008Co-Authors: Lenka Sedlackova, Stephen A RiceAbstract:Early in infection, herpes simplex virus type 1 (HSV-1) Immediate-Early (IE) Proteins ICP0 and ICP4 localize to the nucleus, where they stimulate viral transcription. Later in infection, ICP0 and to a lesser extent ICP4 accumulate in the cytoplasm, but their biological role there is unknown. Previously, it was shown that the cytoplasmic localization of ICP0/4 requires the multifunctional IE Protein ICP27, which is itself an activator of viral gene expression. Here, we identify a viral ICP27 mutant, d3-4, which is unable to efficiently localize ICP0 and ICP4 to the cytoplasm but which otherwise resembles wild-type HSV-1 in its growth and viral gene expression phenotypes. These results genetically separate the function of ICP27 that affects ICP0/4 localization from its other functions, which affect viral growth and gene expression. As both ICP0 and ICP4 are known to be minor virion components, we used d3-4 to test the hypothesis that the cytoplasmic localization of these Proteins is required for their incorporation into viral particles. Consistent with this conjecture, d3-4 virions were found to lack ICP0 in their tegument and to have greatly reduced levels of ICP4. Thus, the cytoplasmic localization of ICP0 and ICP4 appears to be a prerequisite for the assembly of these important transcriptional regulatory Proteins into viral particles. Furthermore, our results show that ICP27 plays a previously unrecognized role in determining the composition of HSV-1 virions.
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herpes simplex virus Immediate Early Protein icp22 triggers loss of serine 2 phosphorylated rna polymerase ii
Journal of Virology, 2007Co-Authors: Kathryn A Fraser, Stephen A RiceAbstract:During eukaryotic mRNA transcription, the synthetic activity and mRNA processing factor interactions of RNA polymerase II (RNAP II) are regulated by phosphorylation of its carboxyl-terminal domain (CTD), with modification occurring primarily on serines 2 and 5 of the CTD. We previously showed that herpes simplex virus type 1 (HSV-1) infection rapidly triggers the loss of RNAP II forms bearing serine 2 phosphorylation (Ser-2P RNAP II). Here we show that the HSV-1 Immediate-Early (IE) Protein ICP22 is responsible for this effect during the IE phase of infection. This activity does not require the viral UL13 Protein kinase, which is required for several other regulatory functions of ICP22. Additionally, we show that transient expression of ICP22 can trigger the loss of Ser-2P RNAP II in transfected cells. Thus, the ability of ICP22 to cause the loss of Ser-2 RNAP II does not require other viral factors or the context of the infected cell. Expression of the HSV-1 ICP22-related Protein US1.5, which corresponds to residues 147 to 420 of ICP22, also triggers a loss of Ser-2P RNAP II in transfected cells, whereas expression of the varicella-zoster virus ICP22 homolog, ORF63, does not. Our study also provides evidence for a second, viral late gene-dependent pathway that triggers loss of Ser-2P RNAP II in infected cells, consistent with the recent work of Dai-Ju et al. (J. Q. Dai-Ju, L. Li, L. A. Johnson, and R. M. Sandri-Goldin, J. Virol. 80:3567-3581, 2006). Therefore, it appears that HSV-1 has evolved redundant mechanisms for triggering the loss of a specific phosphorylated form of RNAP II.
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attenuation of dna dependent Protein kinase activity and its catalytic subunit by the herpes simplex virus type 1 transactivator icp0
Journal of Virology, 1996Co-Authors: Susan P Leesmiller, Stephen A Rice, Melissa C Long, M A Kilvert, Charlotte A SpencerAbstract:The DNA-dependent Protein kinase (DNA-PK) is involved in several fundamental nuclear processes, including DNA double-strand break repair, V(D)J recombination, and transcription by RNA polymerases I and II. In this study, we show that infection of mammalian cells with herpes simplex virus type 1 attenuates DNA-PK activity by specifically depleting the p350/DNA-PKcs catalytic subunit. The half-life of the p350/DNA-PKcs Protein decreases from greater than 24 h to less than 4 h following infection. The depletion of DNA-PK activity and p350/DNA-PKcs abundance is dependent on expression of the viral Immediate-Early Protein ICP0. As ICP0 acts as a promoter-independent transactivator of gene expression, these data suggest that ICP0 may function by directly or indirectly targeting the p350/DNA-PKcs subunit of DNA-PK, thereby altering the inhibitory effects of DNA-PK on RNA polymerase II transcription.
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herpes simplex virus Immediate Early Protein icp22 is required for viral modification of host rna polymerase ii and establishment of the normal viral transcription program
Journal of Virology, 1995Co-Authors: Stephen A Rice, P A Schaffer, Melissa C Long, Charlotte A SpencerAbstract:Infection of cells with herpes simplex virus type 1 (HSV-1) results in a rapid alteration of phosphorylation on the large subunit of cellular RNA polymerase II (RNAP II), most likely on its C-terminal domain (S. A. Rice, M. C. Long, V. Lam, C. A. Spencer, J. Virol. 68:988-1001, 1994). This phosphorylation modification generates a novel form of the large subunit which we have designed IIi. In this study, we examine roles that HSV-1 gene products play in this process. An HSV-1 mutant defective in the Immediate-Early transcriptional activator Protein ICP4 is able to efficiently induce IIi. Viruses having mutations in the genes for the ICP0, ICP6, or ICP27 Proteins are also competent for IIi formation. In contrast, 22/n199, an HSV-1 mutant which contains a nonsense mutation in the gene encoding the Immediate-Early Protein ICP22, is significantly deficient in IIi induction. This effect is seen in Vero cells, where 22/n199 grows relatively efficiently, and in human embryonic lung (HEL) cells, where 22/n199 growth in more restricted. RNAP II is recruited into viral replication compartments in 22/n199-infected cells, indicating that altered phosphorylation of RNAP II is not a prerequisite for nuclear relocalization of RNAP II. In addition, we show by nuclear run-on transcription analysis that viral gene transcription is deficient in HEL cells infected with 22/n199. Viral late gene transcription does not occur efficiently, and antisense transcription throughout the genome is diminished compared with that of the wild-type HSV-1 infection. These transcriptional effects cannot be explained by differences in viral DNA replication, since 22/n199 replicates its DNA efficiently in HEL cells. Our results demonstrated that ICP22 is necessary for virus-induced aberrant phosphorylation of RNAP II and for normal patterns of viral gene transcription in certain cell lines.
Anne Orr - One of the best experts on this subject based on the ideXlab platform.
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the ability of herpes simplex virus type 1 Immediate Early Protein vmw110 to bind to a ubiquitin specific protease contributes to its roles in the activation of gene expression and stimulation of virus replication
Journal of Virology, 1999Co-Authors: Roger D Everett, Michayla Meredith, Anne OrrAbstract:Herpes simplex virus type 1 Immediate-Early Protein Vmw110 stimulates the onset of virus infection and is required for efficient reactivation from latency. In transfection assays, Vmw110 is a potent activator of gene expression, but its mode of action has yet to be determined. Previous work has shown that Vmw110 localizes to specific intranuclear structures known as ND10, PML bodies, or PODs and causes the disruption of these domains. The ability of Vmw110 to disrupt ND10 correlates with its biological activities in infected and transfected cells. It has also been found that Vmw110 binds strongly and specifically to a ubiquitin-specific protease known as HAUSP, itself a component of a subset of ND10. In this study we have investigated the role of HAUSP in Vmw110 activity; single amino acid residues of Vmw110 required for the interaction were identified, and the effects of mutation of these residues in infected and transfected cells were then assayed. The results indicate that the ability to bind to HAUSP contributes to the functional activities of Vmw110.
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the equine herpesvirus 1 gene 63 ring finger Protein partially complements vmw110 its herpes simplex virus type 1 counterpart
Journal of General Virology, 1995Co-Authors: Roger D Everett, Anne Orr, Maggie ElliottAbstract:All alpha herpesviruses of known DNA sequence have been found to encode a Protein with similarities to Immediate Early Protein Vmw110 (ICP0) of herpes simplex virus type 1 (HSV-1). The conserved portion of this family of Proteins is a characteristic zinc binding module, known as a RING finger or C3HC4 domain. Examples of RING finger domains occur in many other Proteins of diverse evolutionary origin and function. Recently, the solution structure of the equine herpesvirus 1 (EHV-1) RING finger Protein, encoded by gene 63, has been solved. To investigate whether this structure could be considered to be a paradigm of herpesvirus RING domains, we have constructed a recombinant HSV-1 which expresses the EHV-1 gene 63 Protein (EHVg63) in place of Vmw110. Comparison of the growth properties of the recombinant with those of wild-type and Vmw110-defective viruses indicates that EHVg63 is able to fulfil partially, but not completely, the roles of Vmw110 during virus growth in tissue culture.
