bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Differential Requirement for Cyclin-Dependent Kinase Activities Distinguishes Two Functions of Herpes Simplex Virus Type 1 ICP0
Authors: Davido David J. , von Zagorski William F. , Maul Gerd G. , Schaffer Priscilla A. 
Published: November 2003

ABSTRACTHerpes simplex virus type 1 (HSV-1) ICP0 directs the degradation of cellular proteins associated with nuclear structures called ND10, a function thought to be closely associated with its broad transactivating activity. Roscovitine (Rosco), an inhibitor of cyclin-dependent kinases (cdks), inhibits the replication of HSV-1, HSV-2, human cytomegalovirus, varicella-zoster virus, and human immunodeficiency virus type 1 by inhibiting specific steps or activities of viral regulatory proteins, indicating the broad and pleiotropic effects that cdks have on the replication of these viruses. We previously demonstrated that Rosco inhibits the transactivating activity of ICP0. In the present study, we asked whether Rosco also affects the ability of ICP0 to direct the degradation of ND10-associated proteins. For this purpose, WI-38 cells treated with cycloheximide (CHX) were mock infected or infected with wild-type HSV-1 or an ICP0−mutant (7134). After release from the CHX block, the infections were allowed to proceed for 2 h in the presence or absence of Rosco at a concentration known to inhibit ICP0's transactivating activity. The cells were then examined for the presence of ICP0 and selected ND10-associated antigens (promyelocytic leukemia antigen [PML], sp100, hDaxx, and NDP55) by immunofluorescence. Staining for the ND10-associated antigens was detected in ≤20% of KOS-infected cells in the presence or absence of Rosco, demonstrating that Rosco-sensitive kinases are not required for ICP0's ability to direct the dispersal or degradation of these antigens. In contrast, >90% of 7134- and mock-infected cells stained positive for all ND10-associated antigens in the presence or absence of Rosco. Similar results were obtained with a non-ND10-associated antigen, DNA-PKcs, a known target of ICP0-directed degradation. The results of the PML and DNA-PKcsimmunofluorescence studies correlated with a decrease in the levels of these proteins as determined by Western blotting. Thus, the differential requirement for Rosco-sensitive cdk activities distinguishes ICP0's ability to direct the dispersal or degradation of cellular proteins from its transactivating activity.
Endoplasmic Reticulum Stress Is a Determinant of Retrovirus-Induced Spongiform Neurodegeneration
Authors: Dimcheff Derek E. , Askovic Srdjan , Baker Audrey H. , Johnson-Fowler Cedar , Portis John L. 
Published: November 2003

ABSTRACTFrCasEis a mouse retrovirus that causes a fatal noninflammatory spongiform neurodegenerative disease with pathological features strikingly similar to those induced by transmissible spongiform encephalopathy (TSE) agents. Neurovirulence is determined by the sequence of the viral envelope protein, though the specific role of this protein in disease pathogenesis is not known. In the present study, we compared host gene expression in the brain stems of mice infected with either FrCasEor the avirulent virus F43, differing from FrCasEin the sequence of the envelope gene. Four of the 12 disease-specific transcripts up-regulated during the preclinical period represent responses linked to the accumulation of unfolded proteins in the endoplasmic reticulum (ER). Among these genes was CHOP/GADD153, which is induced in response to conditions that perturb endoplasmic reticulum function. In vitro studies with NIH 3T3 cells revealed up-regulation of CHOP as well as BiP, calreticulin, and Grp58/ERp57 in cells infected with FrCasEbut not with F43. Immunoblot analysis of infected NIH 3T3 cells demonstrated the accumulation of uncleaved envelope precursor protein in FrCasE- but not F43-infected cells, consistent with ER retention. These results suggest that retrovirus-induced spongiform neurodegeneration represents a protein-folding disease and thus may provide a useful tool for exploring the causal link between protein misfolding and the cytopathology that it causes.
Blocking Immune Evasion as a Novel Approach for Prevention and Treatment of Herpes Simplex Virus Infection
Authors: Judson Kara A. , Lubinski John M. , Jiang Ming , Chang Yueh , Eisenberg Roselyn J. , Cohen Gary H. , Friedman Harvey M. 
Published: November 2003

ABSTRACTMany microorganisms encode immune evasion molecules to escape host defenses. Herpes simplex virus type 1 glycoprotein gC is an immunoevasin that inhibits complement activation by binding complement C3b. gC is expressed on the virus envelope and infected cell surface, which makes gC potentially accessible to blocking antibodies. Mice passively immunized with gC monoclonal antibodies prior to infection were protected against herpes simplex virus challenge only if the gC antibodies blocked C3b binding. Mice treated 1 or 2 days postinfection with gC monoclonal antibodies that block C3b binding had less severe disease than control mice treated with nonimmune immunoglobulin G (IgG). Mice immunized with gC protein produced antibodies that blocked C3b binding to gC. Immunized mice were significantly protected against challenge by wild-type virus, but not against a gC mutant virus lacking the C3b binding domain, suggesting that protection was mediated by antibodies that target the gC immune evasion domain. IgG and complement from subjects immunized with an experimental herpes simplex virus glycoprotein gD vaccine neutralized far more mutant virus defective in immune evasion than wild-type virus, supporting the importance of immune evasion molecules in reducing vaccine potency. These results suggest that it is possible to block immune evasion domains on herpes simplex virus and that this approach has therapeutic potential and may enhance vaccine efficacy.
Interactions between Human Cytomegalovirus IE1-72 and Cellular p107: Functional Domains and Mechanisms of Up-Regulation of Cyclin E/cdk2 Kinase Activity
Authors: Zhang Zhigang , Huong Shu-Mei , Wang Xin , Huang David Y. , Huang Eng-Shang 
Published: November 2003

ABSTRACT
Previous work has demonstrated that the human cytomegalovirus IE1-72 protein is able to bind to the N terminus of p107, and IE1-72 alone is sufficient for alleviation of p107-mediated cell growth suppression. However, the mechanism of this alleviation is unclear. Here, we show that IE1-72 can alleviate p107 inhibition of cyclin E/cdk2 kinase activity. We cotransfected various IE1-72 and p107 constructs into C33A cells and demonstrated that IE1-72 could activate the kinase activity of cyclin E/cdk2. Conversely, IE2-86 did not activate this activity, suggesting that the interaction between p107 and IE1-72 and the subsequent kinase activation are specific. By the use of a series of deletion and point mutants of IE1-72 and p107, we observed that a mutation of the loop region of helix-loop-helix-turn-helix in exon 3 of IE1-72 as well as a mutation of the leucine zipper-2 region in exon 4 of IE1-72 abolished binding to p107. In addition, these two IE1-72 mutants did not alleviate p107 inhibition of cyclin E/cdk2 kinase activity and also failed to alleviate p107 inhibition of the E2F-responsive promoter. Meanwhile, deletion of the N-terminal aa 1 to 175 of p107 abolished both p107 binding with IE1-72 and p107 inhibition of cyclin E/cdk2 kinase activity. This result confirms that the N-terminus aa 1 to 175 region of p107 is a common region where both IE1-72 protein and cyclin E/cdk2 bind. We propose a mechanism in which binding of IE1-72 to p107 displaces cyclin E/cdk2 from p107. Once released from p107, cyclin E/cdk2 is able to function as an active kinase.
Neutralization of Infectivity of Diverse R5 Clinical Isolates of Human Immunodeficiency Virus Type 1 by gp120-Binding 2′F-RNA Aptamers
Authors: Khati Makobetsa , Schüman Michael , Ibrahim Jamal , Sattentau Quentin , Gordon Siamon , James William 
Published: November 2003

ABSTRACTHuman immunodeficiency virus type 1 (HIV-1) has evolved a number of strategies to resist current antiretroviral drugs and the selection pressures of humoral and cellular adaptive immunity. For example, R5 strains, which use the CCR5 coreceptor for entry and are the dominant viral phenotype for HIV-1 transmission and AIDS pathogenesis, are relatively resistant to neutralization by antibodies, as are other clinical isolates. In order to overcome these adaptations, we raised nucleic acid aptamers to the SU glycoprotein (gp120) of the R5 strain, HIV-1Ba-L. These not only bound gp120 with high affinity but also neutralized HIV-1 infectivity in human peripheral blood mononuclear cells (PBMCs) by more than 1,000-fold. Furthermore, these aptamers were able to neutralize the infectivity of R5 clinical isolates of HIV-1 derived from group M (subtypes A, C, D, E, and F) and group O. One aptamer defined a site on gp120 that overlaps partially with the conserved, chemokine receptor-binding, CD4-induced epitope recognized by monoclonal antibody 17b. In contrast to the antibody, the site is accessible to aptamer in the absence of CD4 binding. Neutralizing aptamers such as this could be exploited to provide leads in developing alternative, efficacious anti-HIV-1 drugs and lead to a deeper understanding of the molecular interactions between the virus and its host cell.
Characterization of the Chromosomal Binding Sites andDimerization Partners of the Viral Oncoprotein Meq in Marek'sDisease Virus-Transformed TCells
Authors: Levy Alon M. , Izumiya Yoshihiro , Brunovskis Peter , Xia Liang , Parcells Mark S. , Reddy Sanjay M. , Lee Lucy , Chen Hong-Wu , Kung Hsing-Jien 
Published: November 2003

ABSTRACTMarek's disease virus (MDV) is an acute transforming alphaherpesvirus that causes T-cell lymphomas in chickens. We previously reported the identification of a putative oncogene,meq, that is encoded only by the oncogenic serotype of MDV. The gene product, Meq, is a latent protein that is consistently expressed in MDV-transformed lymphoblastoid cells and tumor cells. Meq has a bZIP (basic leucine zipper) structure resembling the family of Jun/Fos. The mechanism whereby Meq transforms T cells remains poorly understood. In this study, we explored the properties of Meq as a transcriptional factor. We analyzed Meq's dimerization partners and its target genes in MSB-1, an MDV-transformed T-cell line. By using in vitro assays, we first demonstrated Meq's potential to dimerize with a variety of bZIP proteins. We then identified c-Jun as the primary dimerization partner of Meq. Both are found to be colocalized in the nucleus and corecruited to promoters with AP-1 sequences. By using chromatin immunoprecipitation (ChIP), we scanned the entire MDV genome for Meq binding sites and found three regions that were enriched with Meq binding: the MDV lytic replication origin, the promoter for Meq, and the promoter for ICP4. Transactivation assays using the above promoters showed that Meq/Meq homodimers exhibited repression activity, whereas Meq/Jun heterodimers showed activation. Finally, we were able to show by ChIP that Meq is recruited to the interleukin-2 promoter in a region encompassing an AP-1 site. Thus, in addition to providing general knowledge about the transcriptional properties of Meq, our studies revealed for the first time the ability of Meq to interact with the latent MDV and host genomes. Our data suggest, therefore, a role for Meq in viral genome regulation during latency, in addition to its putative causal role in T-cell transformation.
Varicella-Zoster Virus-Infected Human Sensory Neurons Are Resistant to Apoptosis, yet Human Foreskin Fibroblasts Are Susceptible: Evidence for a Cell-Type-Specific Apoptotic Response
Authors: Hood C. , Cunningham A. L. , Slobedman B. , Boadle R. A. , Abendroth A. 
Published: November 2003

ABSTRACTThe induction of apoptosis or programmed cell death in virus-infected cells is an important antiviral defense mechanism of the host, and some herpesviruses have evolved strategies to modulate apoptosis in order to enhance their survival and spread. In this study, we examined the ability of varicella-zoster virus (VZV) to induce apoptosis in primary human dorsal root ganglion neurons and primary human foreskin fibroblasts (HFFs). Three independent methods (annexin V, TUNEL [terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling] staining, and electron microscopy) were used to assess apoptosis in these cells on days 1, 2, and 4 postinoculation. By all three methods, apoptosis was readily detected in VZV-infected HFFs. In stark contrast, apoptosis was not detected during productive VZV infection of neurons. The low-passage clinical isolate Schenke and the tissue culture-adapted ROka strain both induced apoptosis in HFFs but not in neurons, suggesting that this cell-type-specific apoptotic phenotype was not VZV strain specific. These data show that the regulation of apoptosis differs markedly between HFFs and neurons during productive VZV infection. Inhibition of apoptosis during infection of neurons may play a significant role in the establishment, maintenance, and reactivation of latent infection by promoting survival of these postmitotic cells.
Development and Characterization of Novel Empty Adenovirus Capsids and Their Impact on Cellular Gene Expression
Authors: Stilwell Jackie L. , McCarty Douglas M. , Negishi Atsuko , Superfine Richard , Samulski R. Jude 
Published: November 2003

ABSTRACT

Adenovirus (Ad) has been extensively studied as a eukaryotic viral vector. As these vectors have evolved from first-generation vectors to vectors that contain either very few or no viral genes (“gutless” Ad), significant reductions in the host innate immune response upon infection have been observed. Regardless of these vector improvements an unknown amount of toxicity has been associated with the virion structural proteins. Here we demonstrate the ability to generate high particle numbers (10
11
to 10
12
) of Ad empty virions based on a modification of Cre/lox gutless Ad vectors. Using a battery of analyses (electron microscopy, atomic force microscopy, confocal images, and competition assays) we characterized this reagent and determined that it (i) makes intact virion particles, (ii) competes for receptor binding with wild-type Ad, and (iii) enters the cell proficiently, demonstrating an ability to carry out essential steps of viral entry. To further study the biological impact of these Ad empty virions on infected cells, we carried out DNA microarray analysis. Compared to that for recombinant Ad, the number of mRNAs modulated upon infection was significantly reduced but the expression signatures were similar. This reagent provides a valuable tool for studies of Ad in that researchers can examine the effect of infection in the presence of the virion capsid alone.
Rat Model of Borna Disease Virus Transmission: Epidemiological Implications
Authors: Sauder Christian , Staeheli Peter 
Published: November 2003

ABSTRACT
Rapid transmission of Borna disease virus occurred upon cohabitation of persistently infected and naive rats. Infectious virus, which was abundantly present in fresh urine samples of carrier rats, entered the brains of recipient rats via the olfactory route. Thus, susceptible farm animals possibly acquire the virus from persistently infected rats.
Biallelic transcriptional activation of oncogenic transcription factors in T-cell acute lymphoblastic leukemia
Authors: Ferrando Adolfo A. , Herblot Sabine , Palomero Teresa , Hansen Mark , Hoang Trang , Fox Edward A. , Look A. Thomas 
Published: November 2003

Abstract
Aberrant expression of transcription factor oncogenes such as HOX11, HOX11L2, TAL1/SCL, LYL1, LMO1, and LMO2 can be detected in lymphoblasts from up to 80% of patients with acute T-cell lymphoblastic leukemia (T-ALL). Transcriptional activation of these oncogenes in leukemic cells typically results from chromosomal rearrangements that place them next to highly active cis-acting transcriptional regulatory elements. However, biallelic activation of TAL1 in some T-ALL cases has been previously proposed. We have used allele-specific mRNA analysis to show that trans-acting mechanisms leading to biallelic overexpression of TAL1 are involved in 10 (42%) of 24 TAL1+ informative T-ALL cases, 2 (17%) of 12 HOX11+ informative cases, and 7 (64%) of 11 LMO2+ informative cases. We propose that aberrant expression of oncogenic transcription factors in a significant fraction of T-ALLs may result from loss of the upstream transcriptional mechanisms that normally down-regulate the expression of these oncogenes during T-cell development.
Mechanisms of homing in the fiddler crabUca rapax2. Information sources and frame of reference for a path integration system
Authors: Layne John E. , Barnes W. Jon P. , Duncan Lindsey M. J. 
Published: November 2003

SUMMARYFiddler crabs Uca rapax are central-place foragers, making feeding excursions of up to several meters from their burrows. This study investigates the sources of directional and distance information used by these crabs when returning to their burrows. We tested the spatial frame of reference(egocentric or exocentric), and the source of spatial information (idiothetic or allothetic) used during homing. We also tested which components of their locomotion they integrated (only voluntary, or voluntary plus reflexive).Fiddler crabs in their natural mudflat habitat were passively rotated during normal foraging behavior using experimenter-controlled disks, before they returned home. Crabs resisted passive rotations on the disk by counter-rotating when the disk turned, which was a compensatory response to unintended movement. Crabs were usually situated eccentrically on the disk,and therefore were also subjected to a translation when the disk rotated. No crab actively compensated for this translation. Crabs that fully compensated for disk rotation made no directional homing error. Crabs that did not fully compensate homed in a direction that reflected their new body orientation. In other words, if we succeeded in reorienting a crab (i.e. it undercompensated for disk rotation), its homing error was equal to the angle by which it had been reoriented, regardless of the magnitude of the optomotor compensation.Computer-modelled crabs, each equipped with a path integrator utilizing different combinations of external (allothetic) and path-related (idiothetic)input, traversed the digitized paths of the real crabs. The home vector computed by the model crab was then compared to the homing direction observed in the real crab. The model home vector that most closely matched that of the real crab was taken to comprise the path integration mechanism employed by fiddler crabs. The model that best matched the real crab gained direction and distance idiothetically (from internal sources such as proprioceptors), and integrated only voluntary locomotory information.Crabs were also made to run home across a patch of wet acetate, on which they slipped and were thus forced to take more steps on the homeward path than theoretically required by the home vector. Crabs whose running velocity across the patch was unusually low also stopped short of their burrow before finding it. Crabs whose running velocity was not impeded by the patch did not stop short, but ran straight to the burrow entrance, as did control crabs that ran home with no slippery patch. We interpret this to mean that the velocity of some crabs was impeded because of slipping, and these therefore stopped short of their burrow after having run out their homing vector. This is positive evidence in support of the hypothesis that path integration is mediated either by leg proprioceptors or by efferent commands, but our data do not allow us to distinguish between these two possibilities.
Auto-spermatophore extrusion in male crickets
Authors: Kumashiro Mikihiko , Tsuji Yohei , Sakai Masaki 
Published: November 2003

SUMMARYThe reproductive cycle of the male cricket consists of the mating stage and the sexually refractory stage. The latter is further divided into the first refractory stage (RS1) from spermatophore extrusion in copulation to spermatophore preparation after copulation, and the second refractory stage(RS2) from spermatophore preparation to recommencement of a calling song. RS2 is time-fixed and unaffected by the female or by stress, hence RS2 is assumed to be controlled by the reproductive timer. Previously, we suggested that the timer is located in the terminal abdominal ganglion (TAG), because functional inactivation of the TAG by local cooling lengthened RS2 in proportion to cooling time. To obtain further evidence of timer localization and to examine the operation of the timer in dissected animals, we investigated the characteristics of auto-spermatophore extrusion, a phenomenon in which males eject the mature spermatophore themselves without any prior courtship. The occurrence of auto-spermatophore extrusion was 100% in dissected males with the TAG separated, compared to 1.7% in intact males. The time interval (SPaSE)between spermatophore preparation and auto-spermatophore extrusion was comparable to RS2 measured by the calling song. Spike recording from a genital motor neurone in the separated TAG indicated that burst discharge associated with auto-spermatophore extrusion occurred with a SPaSE comparable to RS2. Other efferent neurones, some of which were identified as dorsal unpaired median (DUM) neurones, showed a time-dependent spike frequency increase during SPaSE. These results strengthen our previous conclusion that the reproductive timer is located within the TAG, and demonstrate that the timer functions normally even when the TAG is separated from the central nervous system.
Heterotrophy on ultraplankton communities is an important source of nitrogen for a sponge–rhodophyte symbiosis
Authors: Pile Adele J. , Grant Adrienne , Hinde Rosalind , Borowitzka Michael A. 
Published: November 2003

SUMMARY
Grazing on ultraplankton by the sponge partner of an invertebrate/algal symbiotic association can provide enough particulate organic nitrogen to support the nitrogen needs of both partners. The previously unknown natural diet of the sponge in the Haliclona–Ceratodictyon association consists of bacteria and protozoans, which are rich sources of nitrogen. Retention of ultraplankton varied with season and time of day. During the winter there was an order of magnitude more nitrogen taken up than in summer. Time of day during each season also affected the amount of ultraplankton retained. In summer retention was higher at night whereas the opposite was true during winter. Overall, the Haliclona–Ceratodictyonassociation is able to meet its metabolic nitrogen demands through grazing on the naturally occurring water column community.
Controlling muscle mitochondrial content
Authors: Moyes Christopher D. 
Published: November 2003

SUMMARYMitochondrial content, a chief determinant of aerobic capacity, varies widely among muscle types and species. Mitochondrial enzyme levels in vertebrate skeletal muscles vary more than 100-fold, from fish white muscle to bird flight muscles. Recent studies have shed light on the transcriptional regulators that control mitochondrial gene expression in muscle fiber differentiation and development, and in the context of pathological conditions such as neuromuscular disease and obesity. While the transcriptional co-activator PGC-1α (peroxisome proliferator-activated receptor gamma co-activator 1) has emerged as a master controller of mitochondrial gene expression, it is important to consider other mechanisms by which coordinated changes in mitochondrial content could arise. These studies,largely using biomedical models, provide important information for comparative biologists interested in the mechanistic basis of inter-species variation in muscle aerobic capacity.