bluuebunny/crossref_metadata_2025_split huggingface dataset:
Human T-Cell Leukemia Virus Type 1 Tax Dysregulates β-CateninSignaling
Authors: Tomita Mariko , Kikuchi Akira , Akiyama Tetsu , Tanaka Yuetsu , Mori Naoki 
Published: October 2006

ABSTRACT
Dysregulation
of β-catenin signaling has been implicated in the malignant
transformation of cells. However, the role of β-catenin in the
human T-cell leukemia virus type 1 (HTLV-1)-induced transformation of T
cells is unknown. Here we found that β-catenin protein was
overexpressed in the nucleus and that β-catenin-dependent
transcription was significantly enhanced in Tax-positive
HTLV-1-infected T-cell lines compared to that in Tax-negative
HTLV-1-infected T-cell lines. Transfection withβ
-catenin-specific small interfering RNA inhibited the growth
of the Tax-positive HTLV-1-infected T-cell line HUT-102. Transient
transfection of Tax appeared to enhance β-catenin-dependent
transcription by stabilizing the β-catenin protein via
activation of the cyclic AMP (cAMP) response element-binding protein.
HTLV-1-infected T-cell lines overexpressing β-catenin also
showed increased Akt activity via Tax activation of the cAMP response
element-binding protein, resulting in the phosphorylation and
inactivation of glycogen synthase kinase 3β, which
phosphorylates β-catenin for ubiquitination. The
phosphatidylinositol 3-kinase inhibitor LY294002 reducedβ
-catenin expression in Tax-positive T-cell lines, and
inactivation of glycogen synthase kinase 3β by lithium chloride
restored β-catenin expression in Tax-negative T-cell lines.
Finally, we showed that dominant-negative Akt inhibited Tax-inducedβ
-catenin-dependent transcription. These results indicate that
Tax activates β-catenin through the Akt signaling pathway. Our
findings suggest that activation of β-catenin by Tax may be
important in the transformation of T cells by HTLV-1
infection.
MurineHepatitis Virus Strain 1 Produces a Clinically Relevant Model of Severe Acute Respiratory Syndrome in A/J Mice
Authors: De Albuquerque Nadine , Baig Ehtesham , Ma Xuezhong , Zhang Jianhua , He William , Rowe Andrea , Habal Marlena , Liu Mingfeng , Shalev Itay , Downey Gregory P. , Gorczynski Reginald , Butany Jagdish , Leibowitz Julian , Weiss Susan R. , McGilvray Ian D. , Phillips M. James , Fish Eleanor N. , Levy Gary A. 
Published: October 2006

ABSTRACTSevere acute respiratory syndrome (SARS) is a life-threatening infectious disease which has been difficult to study and treat because of the lack of a readily available animal model. Intranasal infection of A/J mice with the coronavirus murine hepatitis virus strain 1 (MHV-1) produced pulmonary pathological features of SARS. All MHV-1-infected A/J mice developed progressive interstitial pneumonitis, including dense macrophage infiltrates, giant cells, and hyaline membranes, resulting in death of all animals. In contrast, other mouse strains developed only mild transitory disease. Infected A/J mice had significantly higher cytokine levels, particularly macrophage chemoattractant protein 1 (MCP-1/CCL-2), gamma interferon, and tumor necrosis factor alpha. Furthermore, FGL2/fibroleukin mRNA transcripts and protein and fibrin deposits were markedly increased in the lungs of infected A/J mice. These animals developed a less robust type I interferon response to MHV-1 infection than resistant C57BL/6J mice, and treatment with recombinant beta interferon improved survival. This study describes a potentially useful small animal model of human SARS, defines its pathogenesis, and suggests treatment strategies.
Posttranslational Modification and Cell Type-Specific Degradation of Varicella-Zoster Virus ORF29p
Authors: Stallings Christina L. , Silverstein Saul J. 
Published: October 2006

ABSTRACT
The ORF29 gene of varicella-zoster virus encodes a single-stranded DNA binding protein that is predominantly nuclear during lytic infection but appears to be restricted to the cytoplasm of latently infected neurons. Following reactivation, ORF29p accumulates in the nuclei of neurons, suggesting that its confinement to the cytosol may be critical for maintaining quiescence. When autonomously expressed, ORF29p accumulates in the nuclei of fibroblasts and the cytoplasm of cells (guinea pig enteric neurons) and cell lines (U373MG) of neuronal origin. Inhibition of the 26S proteasome redirects the accumulation of ORF29p to the nucleus in cells of neuronal origin. Here, we show that ORF29p is ubiquitinated and sumoylated in 293T cells and subsequently degraded from the N terminus. Ubiquitinated ORF29p accumulates in both the nuclei and the cytoplasm of fibroblasts, but degradation products are seen primarily in the cytoplasm. Modification and degradation of ORF29p occurs in 293T, U373MG, and MeWo cells. Therefore, these processes are ubiquitous; however, the robustness of the degradation process is cell type specific. The proteasome-mediated mechanism of nuclear exclusion in U373MG cells is an active process that is not specific for the endogenous ORF29p nuclear localization signal but can be saturated by protein stabilization or overexpression, which leads to nuclear accumulation of ORF29p. The evidence for ORF29p ubiquitination and previous data regarding the effect of proteasome inhibitors on the abundance and distribution of ORF29p implicate the 26S proteasome in influencing the protein's cell type-specific localization.
The Unique C Termini of Orthopoxvirus Gamma Interferon Binding Proteins Are Essential for Ligand Binding
Authors: Nuara Anthony A. , Bai Hongdong , Chen Nanhai , Buller R. Mark L. , Walter Mark R. 
Published: October 2006

ABSTRACT
The orthopoxviruses ectromelia virus (ECTV) and vaccinia virus (VACV) express secreted gamma interferon binding proteins (IFN-γBPs) with homology to the ligand binding domains of the host's IFN-γ receptor (IFN-γR1). Homology between these proteins is limited to the extracellular portions of the IFN-γR1 and the first ∼200 amino acids of the IFN-γBPs. The remaining 60 amino acids at the C termini of the IFN-γBPs contain a single cysteine residue shown to be important in covalent dimerization of the secreted proteins. The function of the remaining C-terminal domain (CTD) has remained elusive, yet this region is conserved within all orthopoxvirus IFN-γBPs. Using a series of C-terminal deletion constructs, we have determined that the CTD is essential for IFN-γ binding despite having no predicted homology to the IFN-γR1. Truncation of the ECTV IFN-γBP by more than two amino acid residues results in a complete loss of binding activity for both murine IFN-γ and human IFN-γ (hIFN-γ), as measured by surface plasmon resonance (SPR) and bioassay. Equivalent truncation of the VACV IFN-γBP resulted in comparable loss of hIFN-γ binding activity by SPR. Full-length IFN-γBPs were observed to form higher-ordered structures larger than the previously reported dimers. Mutants that were unable to bind IFN-γ with high affinity in SPR experiments failed to assemble into these higher-ordered structures and migrated as dimers. We conclude that the unique CTD of orthopoxvirus IFN-γBPs is important for the assembly of covalent homodimers as well as the assembly of higher-ordered structures essential for IFN-γ binding.
Antilipopolysaccharide Factor Interferes with White Spot Syndrome Virus Replication In Vitro and In Vivo in the Crayfish
Pacifastacus leniusculus
Authors: Liu Haipeng , Jiravanichpaisal Pikul , Söderhäll Irene , Cerenius Lage , Söderhäll Kenneth 
Published: October 2006

ABSTRACT

In a study of genes expressed differentially in the freshwater crayfish
Pacifastacus leniusculus
infected experimentally with the white spot syndrome virus (WSSV), one protein, known as antilipopolysaccharide factor (ALF), was chosen, among those whose transcript levels increased upon viral infection, for further studies. ALF RNA interference (RNAi) experiments in whole animals and in cell cultures indicated that ALF can protect against WSSV infection, since knockdown of ALF by RNAi specifically resulted in higher rates of viral propagation. In a cell culture of hematopoietic tissue (Hpt) from
P. leniusculus
, quantitative PCR showed that knockdown of ALF by RNAi resulted into WSSV levels that were about 10-fold higher than those treated with control double-stranded RNA (dsRNA). In addition, RNAi experiments with other crayfish genes that had been found to be up-regulated by a WSSV infection did not result in any changes of viral loads. Thus, the cell culture does not respond to dsRNA in a similar manner, as shown earlier for dsRNA injected into shrimp, which gave a higher degree of resistance to WSSV infection. If ALF transcription in whole animals was stimulated by the administration of UV-treated WSSV, a partial protection against a subsequent challenge with the active virus was conferred to the host. This is the first crustacean gene product identified with the capacity to interfere with replication of this important pathogen.
Herpes Simplex Virus Type 1 ICP27-Dependent Activation of NF-κB
Authors: Hargett Danna , Rice Stephen , Bachenheimer Steven L. 
Published: October 2006

ABSTRACT
The ability of herpes simplex virus type 1 (HSV-1) to activate NF-κB has been well documented. Beginning at 3 to 5 h postinfection, HSV-1 induces a robust and persistent nuclear translocation of an NF-κB-dependent (p50/p65 heterodimer) DNA binding activity, as measured by electrophoretic mobility shift assay. Activation requires virus binding and entry, as well as de novo infected-cell protein synthesis, and is accompanied by loss of both IκBα and IκBβ. In this study, we identified loss of IκBα as a marker of NF-κB activation, and infection with mutants with individual immediate-early (IE) regulatory proteins deleted indicated that ICP27 was necessary for IκBα loss. Analysis of both N-terminal and C-terminal mutants of ICP27 identified the region from amino acids 21 to 63 as being necessary for IκBα loss. Additional experiments with mutant viruses with combinations of IE genes deleted revealed that the ICP27-dependent mechanism of NF-κB activation may be augmented by functional ICP4. We also analyzed two additional markers for NF-κB activation, phosphorylation of the p65 subunit on Ser276 and Ser536. Phosphorylation of both serines was induced upon HSV infection and required functional ICP4 and ICP27. Pharmacological inhibitor studies revealed that both IκBα and Ser276 phosphorylation were dependent on Jun N-terminal protein kinase activity, while Ser536 phosphorylation was not affected during inhibitor treatment. These results demonstrate that there are several layers of regulation of NF-κB activation during HSV infection, highlighting the important role that NF-κB may play in infection.
Packaging Determinants in the UL11 Tegument Protein of Herpes Simplex Virus Type 1
Authors: Loomis Joshua S. , Courtney Richard J. , Wills John W. 
Published: October 2006

ABSTRACT
The UL11 gene of herpes simplex virus type 1 encodes a 96-amino-acid tegument protein that is myristylated, palmitylated, and phosphorylated and is found on the cytoplasmic faces of nuclear, Golgi apparatus-derived, and plasma membranes of infected cells. Although this protein is thought to play a role in virus budding, its specific function is unknown. Purified virions were found to contain ∼700 copies of the UL11 protein per particle, making it an abundant component of the tegument. Moreover, comparisons of cell-associated and virion-associated UL11 showed that packaging is selective for underphosphorylated forms, as has been reported for several other tegument proteins. Although the mechanism by which UL11 is packaged is unknown, previous studies have identified several sequence motifs in the protein that are important for membrane binding, intracellular trafficking, and interaction with UL16, another tegument protein. To ascertain whether any of these motifs are needed for packaging, a transfection/infection-based assay was used in which mutant forms of the protein must compete with the wild type. In this assay, the entire C-terminal half of UL11 was found to be dispensable. In the N-terminal half, the sites of myristylation and palmitylation, which enable membrane-binding and Golgi apparatus-specific targeting, were found to be essential for efficient packaging. The acidic cluster motif, which is not needed for Golgi apparatus-specific targeting but is involved in recycling the protein from the plasma membrane and for the interaction with UL16, was found to be essential, too. Thus, something other than mere localization of UL11 to Golgi apparatus-derived membranes is needed for packaging. The critical factor is unlikely to be the interaction with UL16 because other mutants that fail to bind this protein (due to removal of the dileucine-like motif or substitutions with foreign acidic clusters) were efficiently packaged. Collectively, these results suggest that UL11 packaging is not driven by a passive mechanism but instead requires trafficking through a specific pathway.
Identification of Major Histocompatibility Complex Class II-Restricted Antigens and Epitopes of the Epstein-Barr Virus by a Novel Bacterial Expression Cloning Approach
Authors: Milosevic Slavoljub , Behrends Uta , Adhikary Dinesh , Mautner Josef 
Published: October 2006

ABSTRACT

Epstein-Barr virus (EBV)-specific T cells have been successfully used to
treat or prevent EBV-positive lymphoproliferative disease in
hematopoietic stem cell transplant recipients, but the antigens
recognized by the infused CD4
+
T cells have remained
unknown. Here, we describe a simple procedure that permits the
identification of viral T-helper (T
H
)-cell antigens and
epitopes. This direct antigen identification method is based on the
random expression of viral polypeptides fused to chloramphenicol
acetyltransferase (CAT) in bacteria, which are subsequently fed to
major histocompatibility complex class II
+
antigen-presenting cells and probed with antigen-specific T cells. The
fusion of antigenic fragments to CAT offers several advantages. First,
chloramphenicol treatment allows the selection of bacteria expressing
antigen-CAT fusion proteins in frame, which greatly reduces the number
of colonies to be screened. Second, antigenic fragments fused to CAT
are expressed at high levels, even when derived from proteins that are
toxic to bacteria. Third, the uniformly high expression level of
antigen-CAT fusion proteins permits the establishment of large and
representative pool sizes. Finally, antigen identification does not
require knowledge of the restriction element and often leads directly
to the identification of the T-cell epitope. Using this approach, the
BALF4 and BNRF1 proteins were identified as targets of the EBV-specific
T-helper-cell response, demonstrating that lytic cycle antigens are a
relevant component of the EBV-specific T
H
-cell
response.
Human Cytomegalovirus IE86 Attenuates Virus- and Tumor Necrosis Factor Alpha-Induced NFκB-Dependent Gene Expression
Authors: Taylor R. Travis , Bresnahan Wade A. 
Published: October 2006

ABSTRACTHuman cytomegalovirus (HCMV) infection regulates a number of genes involved in the host antiviral response. We have previously reported that HCMV attenuates the expression of beta interferon (IFN-β) and a number of proinflammatory chemokines, and this attenuation is mediated by the HCMV immediate-early protein IE86. The present study seeks to identify the mechanism by which IE86 blocks IFN-β expression. We demonstrate that the induction of IFN-β during HCMV infection requires the activation of both the IRF-3 and the NFκB pathways. Therefore, IE86 may target either pathway to block IFN-β expression. Our results show that IE86 does not block IRF-3 phosphorylation, dimerization, nuclear translocation, or target gene expression. However, using gel shift analysis, we demonstrate that IE86 efficiently inhibits virus-induced binding of NFκB to the IFN-β promoter, resulting in attenuation of IFN-β and NFκB-dependent gene expression. Furthermore, IE86 expression inhibits tumor necrosis factor alpha-induced NFκB DNA binding and target gene expression. Together, these results identify IE86 as a NFκB antagonist, which results in the suppression of NFκB-dependent cytokine and chemokine gene expression.
Methylation Status of theEpstein-Barr Virus (EBV) BamHI W Latent Cycle Promoter and Promoter Activity: Analysis with Novel EBV-Positive Burkitt and LymphoblastoidCell Lines
Authors: Hutchings Isabel A. , Tierney Rosemary J. , Kelly Gemma L. , Stylianou Julianna , Rickinson Alan B. , Bell Andrew I. 
Published: October 2006

ABSTRACT
The
Epstein-Barr virus (EBV) latent cycle promoter Wp, present in each
tandemly arrayed copy of the BamHI W region in the EBV genome, drives
expression of the EB viral nuclear antigens (EBNAs) at the initiation
of virus-induced B-cell transformation. Thereafter, an alternative EBNA
promoter, Cp, becomes dominant, Wp activity declines dramatically, and
bisulfite sequencing of EBV-transformed lymphoblastoid cell lines
(LCLs) shows extensive Wp methylation. Despite this, Wp is never
completely silenced in LCLs. Here, using a combination of bisulfite
sequencing and methylation-specific PCR, we show that in standard LCLs
transformed with wild-type EBV isolates, some Wp copies always remain
unmethylated, and in LCLs transformed with a recombinant EBV carrying
just two BamHI W copies, Wp is completely unmethylated. Furthermore, we
have analyzed rare LCLs, recently established using wild-type EBV
isolates, and rare Burkitt lymphoma (BL) cell clones, recently
established from tumors carrying EBNA2-deleted EBV genomes, which
express EBNAs exclusively from Wp-initiated transcripts. Here, in sharp
contrast to standard LCL and BL lines, all resident copies of Wp appear
to be predominantly hypomethylated. Thus, studies of B cells with
atypical patterns of Wp usage emphasize the strong correlation between
the presence of unmethylated Wp sequences and promoter
activity.
LMP1 Transmembrane Domain 1 and 2 (TM1-2) FWLY Mediates Intermolecular Interactions with TM3-6 To Activate NF-κB
Authors: Soni Vishal , Yasui Teruhito , Cahir-McFarland Ellen , Kieff Elliott 
Published: October 2006

ABSTRACT

The Epstein-Barr virus oncoprotein LMP1 has six transmembrane domains (TMs) that enable intermolecular aggregation and constitutive signaling through two C-terminal cytosolic domains. Expression of both TMs 1 and 2 without the C terminus (TM1-2ΔC) and TMs 3 to 6 fused to the C terminus (TM3-6) results in partial association, which is substantially decreased by TM1 F
38
WLY
41
mutation to A
38
ALA
41
. We now investigate whether TM1-2ΔC can functionally interact with TM3-6. TM1-2ΔC induced TM3-6 to mediate NF-κB activation at 59% of LMP1 levels, and the effect was dependent on TM1-2 F
38
WLY
41
. TM1-2ΔC even induced TM3-4 C terminus-mediated NF-κB activation to 44% of LMP1 levels. Surprisingly, this effect was TM1 F
38
WLY
41
independent, indicative of a role for TMs 5 and 6 in TM1 F
38
WLY
41
effects. TM3 W
98
was also important for TM1-2ΔC induction of TM3-6-mediated NF-κB activation, for association, and for TM1 F
38
WLY
41
dependence on C-terminal NF-κB activation. These data support models in which the TM1 F
38
WLY
41
effects are at least partially dependent on TM3 W
98
and a residue(s) in TMs 5 and 6.
CD8 T Cells Control Cytomegalovirus Latency by Epitope-Specific Sensing of Transcriptional Reactivation
Authors: Simon Christian O. , Holtappels Rafaela , Tervo Hanna-Mari , Böhm Verena , Däubner Torsten , Oehrlein-Karpi Silke A. , Kühnapfel Birgit , Renzaho Angélique , Strand Dennis , Podlech Jürgen , Reddehase Matthias J. , Grzimek Natascha K. A. 
Published: October 2006

ABSTRACT

During
murine cytomegalovirus (mCMV) latency in the lungs, most of the viral
genomes are transcriptionally silent at the major immediate-early
locus, but rare and stochastic episodes of desilencing lead to the
expression of IE1 transcripts. This low-frequency but perpetual
expression is accompanied by an activation of lung-resident
effector-memory CD8 T cells specific for the antigenic peptide
168-YPHFMPTNL-176, which is derivedfrom the IE1 protein. These molecular and immunological findings were
combined in the “silencing/desilencing and immune sensing
hypothesis” of cytomegalovirus latency and reactivation. This
hypothesis proposes that IE1 gene expression proceeds to cell surface
presentation of the IE1 peptide by the major histocompatibility complex
(MHC) class I molecule L
d
and that its recognition by CD8 T
cells terminates virus reactivation. Here we provide experimental
evidence in support of this hypothesis. We generated mutant virus
mCMV-IE1-L176A, in which the antigenic IE1 peptide is functionally
deleted by a point mutation of the C-terminal MHC class I anchor
residue Leu into Ala. Two revertant viruses, mCMV-IE1-A176L and the
wobble nucleotide-marked mCMV-IE1-A176L*, in which Leu is restored by
back-mutation of Ala codon GCA into Leu codons CTA and CTT,
respectively, were constructed. Pulmonary latency of the mutant virus
was found to be associated with an increased prevalence of IE1
transcription and with events of IE3 transactivator splicing. In
conclusion, IE1-specific CD8 T cells recognize and terminate virus
reactivation in vivo at the first opportunity in the reactivated gene
expression program. The perpetual gene expression and antigen
presentation might represent the driving molecular force in
CMV-associated
immunosenescence.
Interactions between c-Jun, Nuclear Factor 1, and JC Virus Promoter Sequences: Implications for Viral Tropism
Authors: Ravichandran Veerasamy , Sabath Bruce F. , Jensen Peter N. , Houff Sidney A. , Major Eugene O. 
Published: October 2006

ABSTRACT
The infectious cycle of the human polyomavirus JC (JCV) is ultimately regulated in cellular nuclei at the level of viral protein expression and genomic replication. Such activity is prompted by interactions between variant nucleotide sequences within the JCV regulatory region (promoter) and cellular transcription factors that bind specific DNA consensus sites. In previous work we identified an NF-1 class member, NF-1X, as a critical transcription factor affecting the JCV cellular host range. Within variant JCV promoters, as well as other viral and cellular promoters, adjacently located NF-1 and AP-1 consensus sites are often found. The close proximity of these two binding sites suggests the opportunity for interaction between NF-1 and AP-1 proteins. Here, by electrophoretic mobility shift assays, we show temporal and dose-dependent interference by an AP-1 family member, c-Jun, upon NF-1 proteins binding an NF-1 consensus site derived from JCV promoter sequence. Moreover, as demonstrated by protein-protein interaction assays, we identify specific binding affinity independent of DNA binding between NF-1X and c-Jun. Finally, to compare the binding profiles of NF-1X and c-Jun on JCV promoter sequence in parallel with in vivo detection of viral activity levels, we developed an anchored transcriptional promoter (ATP) assay. With use of extracts from JCV-infected cells transfected to overexpress either NF-1X or c-Jun, ATP assays showed concurrent increases in NF-1X binding and viral protein expression. Conversely, increased c-Jun binding accompanied decreases in both NF-1X binding and viral protein expression. Therefore, inhibition of NF-1X binding by c-Jun appears to play a role in regulating levels of JCV activity.