bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nuclear Import Defect of Human Immunodeficiency Virus Type 1 DNA Flap Mutants Is Not Dependent on the Viral Strain or Target Cell Type
Authors: Arhel Nathalie , Munier Sandie , Souque Philippe , Mollier Karine , Charneau Pierre 
Published: September 2006

ABSTRACTWe have previously established, using human immunodeficiency virus type 1 (HIV-1) strain LAI, that the HIV-1 central DNA Flap acts as acisdeterminant of viral genome nuclear import. Although the impact of the DNA Flap on nuclear import has already found numerous independent confirmations in the context of lentivirus vectors, it has been claimed that it may be nonessential for infectious virus strains LAI, YU-2 (J. D. Dvorin et al., J. Virol.76:12087-12096, 2002), HXB2, and NL4-3 (A. Limon et al., J. Virol.76:12078-12086, 2002). We conducted a detailed analysis of virus infectivity using the provirus clones provided by the authors and analogous target cells. In contrast to published data, our results show that all cPPT mutant viruses exhibit reduced infectivity corresponding to a nuclear import defect irrespective of the viral genetic background or target cell.
Catalytic Core of Alphavirus Nonstructural Protein nsP4 Possesses Terminal Adenylyltransferase Activity
Authors: Tomar Shailly , Hardy Richard W. , Smith Janet L. , Kuhn Richard J. 
Published: September 2006

ABSTRACT

The RNA-dependent RNA polymerase nsP4 is an integral part of the alphavirus replication complex. To define the role of nsP4 in viral RNA replication and for a structure-function analysis, we expressed Sindbis virus nsP4 in
Escherichia coli
. The core catalytic domain of nsP4 (Δ97nsP4, a deletion of the N-terminal 97 amino acids), which consists of the predicted polymerase domain containing the GDD amino acid motif required for viral RNA synthesis, was stable against proteolytic degradation during expression. Therefore, the recombinant core domain and selected mutants were expressed and purified to homogeneity. We determined that Δ97nsP4 possesses terminal adenylyltransferase (TATase) activity, as it specifically catalyzed the addition of adenine to the 3′ end of an acceptor RNA in the presence of divalent cations. Furthermore, Δ97nsP4 is unable to transfer other nucleotides (UTP, CTP, GTP, and dATP) to the acceptor RNA in the absence or presence of other nucleotides. Δ97nsP4 possessing a GDD-to-GAA mutation completely inactivates the enzymatic activity. However, a GDD-to-SNN mutation did not inactivate the enzyme but reduced its activity to ∼45% of that of the wild type in the presence of Mg
2+
. Investigation of the TATase of the GDD-to-SNN mutant revealed that it had TATase equivalent to that of the wild type in the presence of Mn
2+
. Identification of Δ97nsP4 TATase activity suggests a novel function of the alphavirus RNA-dependent RNA polymerase in the maintenance and repair of the poly(A) tail, an element required for replication of the viral genome.
Efficient Mother-to-Child Transfer of Antiretroviral Immunity in the Context of Preclinical Monoclonal Antibody-Based Immunotherapy
Authors: Gros Laurent , Pelegrin Mireia , Plays Marc , Piechaczyk Marc 
Published: September 2006

ABSTRACT

When mice under the age of 5 to 6 days are infected, the FrCas
E
retrovirus induces a neurodegenerative disease leading to death within 1 to 2 months. We have recently reported that transient treatment with a neutralizing monoclonal antibody (MAb) shortly after infection, in addition to an expected immediate decrease in the viral load, also favors the development of a strong protective immune response that persists long after the MAb has been cleared. This observation may have important therapeutic consequences, as it suggests that MAbs might be used, not only as direct neutralizing agents, but also as immunomodulatory agents enabling patients to mount their own antiviral immune responses. We have investigated whether immunoglobulins from mothers who displayed a strong anti-FrCas
E
humoral response induced upon MAb treatment could affect both viremia and the immune systems of FrCas
E
-infected pups till adult age upon placental and/or breastfeeding transfer. The strongest effects, i.e., reduction in the viral load and induction of protective humoral antiviral responses, were observed upon breastfeeding alone and breastfeeding plus placental immunity transfer. However, placental transfer of anti-FrCas
E
antibodies was sufficient to both protect neonatally infected animals and help them initiate a neutralizing anti-FrCas
E
response. Also, administration of a neutralizing MAb to naive mothers during late gestation and breastfeeding could generate similar effects. Taken together, our data support the concept that passive immunotherapies during late gestation and/or breastfeeding might help retrovirally infected neonates prime their own protective immune responses, in addition to exerting an immediate antiviral effect.
Induction of a Protective Immune Response against Viral Nervous Necrosis in the European Sea Bass
Dicentrarchus labrax
by Using Betanodavirus Virus-Like Particles
Authors: Thiéry R. , Cozien J. , Cabon J. , Lamour F. , Baud M. , Schneemann A. 
Published: September 2006

ABSTRACT

Betanodaviruses are causative agents of viral nervous necrosis (VNN), a devastating disease of cultured marine fish worldwide. Virus particles contain a single type of coat protein that spontaneously assembles into virus-like particles (VLPs) when expressed in a baculovirus expression system. In the present study, the immunogenicity of betanodavirus VLPs and the protection they confer against VNN in the European sea bass
Dicentrarchus labrax
were investigated. Enzyme-linked immunosorbent assay and seroneutralization tests performed on plasma from fish vaccinated intramuscularly with doses as low as 0.1 μg of VLPs indicated that the VLPs elicited the synthesis of specific antibetanodavirus antibodies with neutralizing activity. Moreover, fish vaccinated with VLPs were protected from challenge with live virus. Both the immune response and the protective effect against viral challenge were dose dependent. Reverse transcription-PCR data indicated that higher doses of vaccine also reduced the number of fish containing detectable quantities of betanodavirus RNA on day 30 after challenge. Taken together these data strongly support the hypothesis that VLPs obtained in the baculovirus expression system may represent an effective vaccine against VNN.
Asynchronous Progression through the Lytic Cascade and Variations in Intracellular Viral Loads Revealed by High-Throughput Single-Cell Analysis of Kaposi's Sarcoma-Associated Herpesvirus Infection
Authors: Adang Laura A. , Parsons Christopher H. , Kedes Dean H. 
Published: September 2006

ABSTRACT
Kaposi's sarcoma-associated herpesvirus (KSHV or human herpesvirus-8) is frequently tumorigenic in immunocompromised patients. The average intracellular viral copy number within infected cells, however, varies markedly by tumor type. Since the KSHV-encoded latency-associated nuclear antigen (LANA) tethers viral episomes to host heterochromatin and displays a punctate pattern by fluorescence microscopy, we investigated whether accurate quantification of individual LANA dots is predictive of intracellular viral genome load. Using a novel technology that integrates single-cell imaging with flow cytometry, we found that both the number and the summed immunofluorescence of individual LANA dots are directly proportional to the amount of intracellular viral DNA. Moreover, combining viral (immediate early lytic replication and transcription activator [RTA] and late lytic K8.1) and cellular (syndecan-1) staining with image-based flow cytometry, we were also able to rapidly and simultaneously distinguish among cells supporting latent, immediate early lytic, early lytic, late lytic, and a potential fourth “delayed late” category of lytic replication. Applying image-based flow cytometry to KSHV culture models, we found that de novo infection results in highly varied levels of intracellular viral load and that lytic induction of latently infected cells likewise leads to a heterogeneous population at various stages of reactivation. These findings additionally underscore the potential advantages of studying KSHV biology with high-throughput analysis of individual cells.
Tyro3 Family-Mediated Cell Entry of Ebola and Marburg Viruses
Authors: Shimojima Masayuki , Takada Ayato , Ebihara Hideki , Neumann Gabriele , Fujioka Kouki , Irimura Tatsuro , Jones Steven , Feldmann Heinz , Kawaoka Yoshihiro 
Published: September 2006

ABSTRACT

Filoviruses, represented by the genera
Ebolavirus
and
Marburgvirus
, cause a lethal hemorrhagic fever in humans and in nonhuman primates. Although filovirus can replicate in various tissues or cell types in these animals, the molecular mechanisms of its broad tropism remain poorly understood. Here we show the involvement of members of the Tyro3 receptor tyrosine kinase family—Axl, Dtk, and Mer—in cell entry of filoviruses. Ectopic expression of these family members in lymphoid cells, which otherwise are highly resistant to filovirus infection, enhanced infection by pseudotype viruses carrying filovirus glycoproteins on their envelopes. This enhancement was reduced by antibodies to Tyro3 family members, Gas6 ligand, or soluble ectodomains of the members. Live Ebola viruses infected both Axl- and Dtk-expressing cells more efficiently than control cells. Antibody to Axl inhibited infection of pseudotype viruses in a number of Axl-positive cell lines. These results implicate each Tyro3 family member as a cell entry factor in filovirus infection.
Active MAC-1 (CD11b/CD18) on DCs inhibits full T-cell activation
Authors: Varga Georg , Balkow Sandra , Wild Martin K. , Stadtbaeumer Andrea , Krummen Mathias , Rothoeft Tobias , Higuchi Tetsuya , Beissert Stefan , Wethmar Klaus , Scharffetter-Kochanek Karin , Vestweber Dietmar , Grabbe Stephan 
Published: September 2006

AbstractThe β2 integrins are important for transendothelial migration of leukocytes as well as for T-cell activation during antigen presentation. Despite abundant expression of β2 integrins on antigen-presenting cells (APCs), their functional relevance for antigen presentation is completely unclear. We show here that dendritic cells (DCs) from CD18-deficient mice, which lack all functional β2 integrins, have no defect in antigen presentation. Moreover, DCs from normal mice express inactive β2 integrins that do not become activated on contact with T cells, at least in vitro. Pharmacologic activation of β2 integrins on DCs results in a significant reduction of their T cell–activating capacity. This effect is mediated by Mac-1 (CD11b/CD18) on DCs because it could be reversed via blocking antibodies against CD18 and CD11b. Furthermore, the antigen-presenting capacity of macrophages, which express constitutively active β2 integrins, is significantly enhanced on Mac-1 blockade. We therefore conclude that active CD11b/CD18 (Mac-1) on APCs directly inhibits T-cell activation.
Risk- and response-based classification of childhood B-precursor acute lymphoblastic leukemia: a combined analysis of prognostic markers from the Pediatric Oncology Group (POG) and Children's Cancer Group (CCG)
Authors: Schultz Kirk R. , Pullen D. Jeanette , Sather Harland N. , Shuster Jonathan J. , Devidas Meenakshi , Borowitz Michael J. , Carroll Andrew J. , Heerema Nyla A. , Rubnitz Jeffrey E. , Loh Mignon L. , Raetz Elizabeth A. , Winick Naomi J. , Hunger Stephen P. , Carroll William L. , Gaynon Paul S. , Camitta Bruce M. 
Published: September 2006

Abstract
The Children's Cancer Group (CCG) and the Pediatric Oncology Group (POG) joined to form the Children's Oncology Group (COG) in 2000. This merger allowed analysis of clinical, biologic, and early response data predictive of event-free survival (EFS) in acute lymphoblastic leukemia (ALL) to develop a new classification system and treatment algorithm. From 11 779 children (age, 1 to 21.99 years) with newly diagnosed B-precursor ALL consecutively enrolled by the CCG (December 1988 to August 1995, n = 4986) and POG (January 1986 to November 1999, n = 6793), we retrospectively analyzed 6238 patients (CCG, 1182; POG, 5056) with informative cytogenetic data. Four risk groups were defined as very high risk (VHR; 5-year EFS, 45% or below), lower risk (5-year EFS, at least 85%), and standard and high risk (those remaining in the respective National Cancer Institute [NCI] risk groups). VHR criteria included extreme hypodiploidy (fewer than 44 chromosomes), t(9;22) and/or BCR/ABL, and induction failure. Lower-risk patients were NCI standard risk with either t(12;21) (TEL/AML1) or simultaneous trisomies of chromosomes 4, 10, and 17. Even with treatment differences, there was high concordance between the CCG and POG analyses. The COG risk classification scheme is being used for division of B-precursor ALL into lower- (27%), standard- (32%), high- (37%), and very-high- (4%) risk groups based on age, white blood cell (WBC) count, cytogenetics, day-14 marrow response, and end induction minimal residual disease (MRD) by flow cytometry in COG trials.
Eosinophils are a major intravascular location for tissue factor storage and exposure
Authors: Moosbauer Christine , Morgenstern Eberhard , Cuvelier Susan L. , Manukyan Davit , Bidzhekov Kiril , Albrecht Sybille , Lohse Peter , Patel Kamala D. , Engelmann Bernd 
Published: September 2006

Abstract
Blood cell progenitors were scanned for the presence of the coagulation starter protein tissue factor (TF) by immunoelectron microscopy. Thereby, substantial TF expression was observed in the precursor cells of eosinophils. TF levels were lower in basophil precursors and barely detectable in neutrophil progenitors. In peripheral blood immediately processed to avoid activation of the TF gene, mature eosinophils were found to considerably express TF, unique among the granulocyte and monocyte fractions. TF was preferentially located in the specific granules in resting eosinophils. Platelet-activating factor (PAF), and more pronounced, granulocyte-macrophage colony-stimulating factor (GM-CSF) plus PAF, caused translocation of preformed TF to the eosinophil cell membrane. GM-CSF/PAF also increased the TF transcript levels. The activated eosinophils exhibited procoagulant activity that was abrogated by TF inhibition. Targeting the extracellular domain of TF with specific antibodies markedly suppressed the initial phase of the eosinophil passage across the IL-4–activated endothelium. Eosinophil rolling and firm adhesion remained unaffected. This suggests that TF specifically facilitates the early transendothelial migration of the eosinophils. In summary, eosinophils maintain a high TF expression during maturation, providing a main source of preformed TF in blood, which might be relevant for the thrombogenesis promoted by hypereosinophilic conditions.
B-cell receptor signaling in chronic lymphocytic leukemia cells is regulated by overexpressed active protein kinase CβII
Authors: Abrams Simon T. , Lakum Tasneem , Lin Ke , Jones Gemma M. , Treweeke Andrew T. , Farahani Mosavar , Hughes Mair , Zuzel Mirko , Slupsky Joseph R. 
Published: September 2006

AbstractSignals through the B-cell antigen receptor (BCR) are important for the survival of chronic lymphocytic leukemia (CLL) cells. Therefore, factors that influence these signals have important pathophysiological roles in this disease. One key mediator of BCR signaling is protein kinase C β (PKCβ), which regulates the activation of I-κB kinases and the deactivation of Bruton tyrosine kinase within the signaling pathways initiated by BCR engagement. The present study demonstrates that overexpression of the PKCβII isoform is a feature of CLL cells and that activity of this enzyme strongly correlates with CLL cell response to BCR engagement. Thus, intracellular Ca2+ release and increases in cell survival after BCR cross-linking were significantly greater in CLL patients with low levels than in CLL patients with high levels of active PKCβII. Furthermore, BCR-induced Ca2+ fluxes could be restored in CLL patients with high levels of active PKCβII by pretreating the cells with the PKCβ-specific inhibitor LY379196. Conversely, BCR-mediated intracellular Ca2+ release could be inhibited in CLL cells with low levels of active PKCβII by pretreatment with the PKC agonist bryostatin. Taken together, these results demonstrate that overexpressed active PKCβII plays a role in the regulation and outcome of BCR signals that can be important for the progression of CLL.
Increased plasma transferrin, altered body iron distribution, and microcytic hypochromic anemia in ferrochelatase-deficient mice
Authors: Lyoumi Saïd , Abitbol Marie , Andrieu Valérie , Henin Dominique , Robert Elodie , Schmitt Caroline , Gouya Laurent , de Verneuil Hubert , Deybach Jean-Charles , Montagutelli Xavier , Beaumont Carole , Puy Hervé 
Published: September 2006

AbstractPatients with deficiency in ferrochelatase (FECH), the last enzyme of the heme biosynthetic pathway, experience a painful type of skin photosensitivity called erythropoietic protoporphyria (EPP), which is caused by the excessive production of protoporphyrin IX (PPIX) by erythrocytes. Controversial results have been reported regarding hematologic status and iron status of patients with EPP. We thoroughly explored these parameters in Fechm1Pas mutant mice of 3 different genetic backgrounds. FECH deficiency induced microcytic hypochromic anemia without ringed sideroblasts, little or no hemolysis, and no erythroid hyperplasia. Serum iron, ferritin, hepcidin mRNA, and Dcytb levels were normal. The homozygous Fechm1Pas mutant involved no tissue iron deficiency but showed a clear-cut redistribution of iron stores from peripheral tissues to the spleen, with a concomitant 2- to 3-fold increase in transferrin expression at the mRNA and the protein levels. Erythrocyte PPIX levels strongly correlated with serum transferrin levels. At all stages of differentiation in our study, transferrin receptor expression in bone marrow erythroid cells in Fechm1Pas was normal in mutant mice but not in patients with iron-deficiency anemia. Based on these observations, we suggest that oral iron therapy is not the therapy of choice for patients with EPP and that the PPIX–liver transferrin pathway plays a role in the orchestration of iron distribution between peripheral iron stores, the spleen, and the bone marrow.
Edelfosine and perifosine induce selective apoptosis in multiple myeloma by recruitment of death receptors and downstream signaling molecules into lipid rafts
Authors: Gajate Consuelo , Mollinedo Faustino 
Published: September 2006

AbstractMultiple myeloma (MM) is an incurable B-cell malignancy, requiring new therapeutic strategies. We have found that synthetic alkyl-lysophospholipids (ALPs) edelfosine and perifosine induced apoptosis in MM cell lines and patient MM cells, whereas normal B and T lymphocytes were spared. ALPs induced recruitment of Fas/CD95 death receptor, Fas-associated death domain–containing protein, and procaspase-8 into lipid rafts, leading to the formation of the death-inducing signaling complex (DISC) and apoptosis. TNF-related apoptosis-inducing ligand receptor-1/death receptor 4 (TRAIL-R1/DR4) and TRAIL-R2/DR5, as well as Bid, were also recruited into lipid rafts, linking death receptor and mitochondrial signaling pathways. ALPs induced mitochondrial cytochrome c release. Bcl-XL overexpression prevented cytochrome c release and apoptosis. A Fas/CD95-deficient MM subline expressing DR4 and DR5 was resistant to edelfosine. Fas/CD95 retrovirus transduction bestowed edelfosine sensitivity in these cells. A Fas/CD95 mutant lacking part of the intracellular domain was ineffective. Lipid raft disruption prevented ALP-induced Fas/CD95 clustering, DISC formation, and apoptosis. ALP-induced apoptosis was Fas/CD95 ligand (FasL/CD95L) independent. ALP-induced recruitment of death receptors in lipid rafts potentiated MM cell killing by FasL/CD95L and TRAIL. These data uncover a novel lipid raft–mediated therapy in MM involving concentration of death receptors in membrane rafts, with Fas/CD95 playing a major role in ALP-mediated apoptosis.
ADAP is required for normal αIIbβ3 activation by VWF/GP Ib-IX-V and other agonists
Authors: Kasirer-Friede Ana , Moran Barry , Nagrampa-Orje Jennifer , Swanson Ken , Ruggeri Zaverio M. , Schraven Burkhart , Neel Benjamin G. , Koretzky Gary , Shattil Sanford J. 
Published: September 2006

AbstractInteraction between von Willebrand factor (VWF) and platelet GP Ib-IX-V is required for hemostasis, in part because intracellular signals from VWF/GP Ib-IX-V activate the ligand-binding function of integrin αIIbβ3. Because they also induce tyrosine phosphorylation of the ADAP adapter, we investigated ADAP's role in GP Ib-IX-V signal transduction. Fibrinogen or ligand-mimetic POW-2 Fab binding to αIIbβ3 was stimulated by adhesion of ADAP+/+ murine platelets to dimeric VWF A1A2 but was significantly reduced in ADAP−/− platelets (P < .01). αIIbβ3 activation by ADP or a Par4 thrombin receptor agonist was also decreased in ADAP−/− platelets. ADAP stabilized the expression of another adapter, SKAP-HOM, via interaction with the latter's SH3 domain. However, no abnormalities in αIIbβ3 activation were observed in SKAP-HOM−/− platelets, which express normal ADAP levels, further implicating ADAP as a modulator of αIIbβ3 function. Under shear flow conditions over a combined surface of VWF A1A2 and fibronectin to test interactions involving GP Ib-IX-V and αIIbβ3, respectively, ADAP−/− platelets displayed reduced αIIbβ3-dependent stable adhesion. Furthermore, ADAP−/− mice demonstrated increased rebleeding from tail wounds. These studies establish ADAP as a component of inside-out signaling pathways that couple GP Ib-IX-V and other platelet agonist receptors to αIIbβ3 activation.
STAT3 and MAPK signaling maintain overexpression of heat shock proteins 90α and β in multiple myeloma cells, which critically contribute to tumor-cell survival
Authors: Chatterjee Manik , Jain Sarika , Stühmer Thorsten , Andrulis Mindaugas , Ungethüm Ute , Kuban Ralf-Jürgen , Lorentz Heike , Bommert Kurt , Topp Max , Krämer Doris , Müller-Hermelink Hans Konrad , Einsele Hermann , Greiner Axel , Bargou Ralf C. 
Published: September 2006

Abstract
The combined blockade of the IL-6R/STAT3 and the MAPK signaling pathways has been shown to inhibit bone marrow microenvironment (BMM)–mediated survival of multiple myeloma (MM) cells. Here, we identify the molecular chaperones heat shock proteins (Hsp) 90α and β as target genes of both pathways. The siRNA-mediated knockdown of Hsp90 or treatment with the novel Hsp90 inhibitor 17-DMAG attenuated the levels of STAT3 and phospho-ERK and decreased the viability of MM cells. Although knockdown of Hsp90β—unlike knockdown of Hsp90α—was sufficient to induce apoptosis, this effect was strongly increased when both Hsp90s were targeted, indicating a cooperation of both. Given the importance of the BMM for drug resistance and MM-cell survival, apoptosis induced by Hsp90 inhibition was not mitigated in the presence of bone marrow stromal cells, osteoclasts, or endothelial cells. These observations suggest that a positive feedback loop consisting of Hsp90α/β and major signaling pathways supports the survival of MM cells. Finally, in situ overexpression of both Hsp90 proteins was observed in most MMs but not in monoclonal gammopathy of undetermined significance (MGUS) or in normal plasma cells. Our results underpin a role for Hsp90α and β in MM pathogenesis.