bluuebunny/crossref_metadata_2025_split huggingface dataset:
Transendothelial migration leads to protection from starvation-induced apoptosis in CD34+CD14+circulating precursors: evidence for PECAM-1 involvement through Akt/PKB activation
Authors: Ferrero Elisabetta , Belloni Daniela , Contini Paola , Foglieni Chiara , Ferrero Maria Elena , Fabbri Monica , Poggi Alessandro , Zocchi Maria Raffaella 
Published: December 2002

AbstractIn the present paper we show that transendothelial migration of a subset of CD14+ circulating leukocytes, coexpressing the CD34 precursor marker, leads to protection from the apoptosis that follows growth factor(s) withdrawal. The resistance of this cell subset to starvation-induced programmed cell death, lasting from 48 to 96 hours, is accompanied by a rise of mitochondrial adenosine triphosphate (ATP), a high nicotinamide adenine dinucleotide (NAD)/reduced nicotinamide adenine dinucleotide (NADH) ratio, and by the up-regulation of expression of the antiapoptotic proteins Bcl-2 and Bcl-X, together with an increase in the cytoplasmic, inactive, form of Bax. This suggests that protection from apoptosis is due to the preservation of mitochondrial function(s). Interestingly, ligation of the platelet endothelial cell adhesion molecule-1 (PECAM-1), which drives CD14+CD34+ transendothelial migration, leads to an increase in Bcl-2 A1 and Bcl-X intracellular content, and to protection from starvation-induced apoptosis. This event is dependent on the engagement of phosphatidylinositol-3 kinase and activation of Akt/PKB that is known to contribute to Bcl-2 and Bcl-X induction. These data point to a critical role of endothelium in preventing the apoptotic program triggered by starvation, possibly inducing a prolonged survival of antigen presenting cell precursors, in order to allow recirculation of these cells and localization to the site of priming of T lymphocytes.
Hypoxic up-regulation of erythroid 5-aminolevulinate synthase
Authors: Hofer Thomas , Wenger Roland H. , Kramer Marianne F. , Ferreira Gloria C. , Gassmann Max 
Published: December 2002

AbstractThe erythroid-specific isoform of 5-aminolevulinate synthase (ALAS2) catalyzes the rate-limiting step in heme biosynthesis. The hypoxia-inducible factor–1 (HIF-1) transcriptionally up-regulates erythropoietin, transferrin, and transferrin receptor, leading to increased erythropoiesis and hematopoietic iron supply. To test the hypothesis that ALAS2 expression might be regulated by a similar mechanism, we exposed murine erythroleukemia cells to hypoxia (1% O2) and found an up to 3-fold up-regulation of ALAS2 mRNA levels and an increase in cellular heme content. A fragment of the ALAS2 promoter ranging from −716 to +1 conveyed hypoxia responsiveness to a heterologous luciferase reporter gene construct in transiently transfected HeLa cells. In contrast, iron depletion, known to induce HIF-1 activity but inhibit ALAS2 translation, did not increase ALAS2 promoter activity. Mutation of a previously predicted HIF-1–binding site (−323/−318) within this promoter fragment and DNA-binding assays revealed that hypoxic up-regulation is independent of this putative HIF-1 DNA-binding site.
Most antiviral CD8 T cells during chronic viral infection do not express high levels of perforin and are not directly cytotoxic
Authors: Zhang Dong , Shankar Premlata , Xu Zhan , Harnisch Brooke , Chen Gang , Lange Christoph , Lee Sandra J. , Valdez Hernan , Lederman Michael M. , Lieberman Judy 
Published: December 2002

AbstractDespite the frequency of HIV-specific CD8 T cells, most HIV-infected patients do not control viral replication without antiviral drugs. Although CD8 T cells are important in containing acute HIV and simian immunodeficiency virus (SIV) infection, CD8 T-cell functions are compromised in chronic infection. To investigate whether functional deficits are specific to HIV, the phenotypic and functional properties of HIV, Epstein-Barr virus (EBV), and cytomegalovirus (CMV)–specific CD8 T cells, labeled with HLA A2.1 or B8 tetramers, were compared in 35 HIV-infected and 9 healthy donors. Cytotoxic T lymphocytes express the cytolytic molecules perforin and granzymes, and are thought to be CD45RA+CD27−. Although most HIV- specific cells are antigen experienced and express granzyme A (median, 85%), few express high levels of perforin (median, 10%) or CD45RA (median, 14%) or have down-modulated CD27 (median, 12%). Perforin expression by HIV-specific cells is not significantly different from that of EBV- or CMV-specific cells in the same donors or in healthy donors. EBV- and CMV-specific cells, like HIV-specific cells, are often not cytotoxic when tested directly ex vivo. HIV-specific T-cell expression of other phenotypic markers is similar to that of EBV- and CMV-specific CD8 T cells in healthy donors. However, CMV-specific cells (and, to a lesser extent, EBV-specific cells) in HIV-infected donors are more likely to be CD27−, CD45RA+, and GzmA+. These results suggest that the chance to eradicate an infection by T-cell–mediated lysis may be undermined once an infection becomes chronic. Impaired antiviral cytotoxicity during chronic infection is not specific to HIV but likely represents the immune response to chronic antigenic exposure.
Differential distribution and internal translation efficiency of hepatitis C virus quasispecies present in dendritic and liver cells
Authors: Laporte Julien , Bain Christine , Maurel Patrick , Inchauspe Genevieve , Agut Henri , Cahour Annie 
Published: December 2002

AbstractHepatitis C virus (HCV) is predominantly a hepatotropic virus. Nonetheless, there is mounting evidence that hematopoietic cells may support HCV replication. The HCV 5′ untranslated region (5′UTR), responsible for initiation of viral translation, via an internal ribosome entry site (IRES), has been previously described to contain specific nucleotide substitutions when cultured in infected lymphoid cells. Our purpose was to establish whether the 5′UTR polymorphism of quasispecies from 3 cell compartments (liver, peripheral blood mononuclear cells [PBMG], and monocyte-derived dendritic cells [DCs]) of a patient chronically infected with HCV1b affects the corresponding translational efficiencies and thus the capacity for replication. The 5′UTR polymorphism was characterized by identification of changes at 3 crucial sites as compared with the reference nucleotide (nt) sequence: a G insertion between positions 19 and 20, a C&gt;A substitution at position 204 and a G&gt;A substitution at position 243. The quasispecies detected in DCs was unique and differed from those present in the liver, suggesting a particular tropism of HCV quasispecies for DCs. Moreover, its translational activity was significantly impaired when compared with those from liver and PBMCs in different cell lines. This impairment was thoroughly confirmed in primary cultures of both human hepatocytes and monocyte-derived DCs. Taken together, our data lend support both to a specific location and impaired replication of HCV quasispecies in DCs, which could be related to viral persistence and perturbation of DC function in chronically infected patients.
CCR7-mediated physiological lymphocyte homing involves activation of a tyrosine kinase pathway
Authors: Stein Jens V. , Soriano Silvia F. , M'rini Christine , Nombela-Arrieta César , González de Buitrago Gonzalo , Rodrı́guez-Frade José Miguel , Mellado Mario , Girard Jean-Philippe , Martı́nez-A. Carlos 
Published: December 2002

AbstractHoming of blood-borne lymphocytes to peripheral lymph nodes (PLNs) is a multistep process dependent on the sequential engagement of L-selectin, which mediates lymphocyte rolling along the luminal surface of high endothelial venules (HEVs), followed by activation of lymphocyte integrins and transmigration through HEVs. Within lymphoid tissue, B and T lymphocytes then migrate toward specific microenvironments such as B-cell follicles and the paracortex, respectively. The lymphocyte-expressed chemokine receptor CCR7 is playing an important role during this process, as its HEV-presented ligands CCL19 and CCL21 can trigger rapid integrin activation under flow in addition to inducing a chemotactic response, which may participate in transmigration and/or interstitial migration. Here, we report that Tyrphostin (Tyr) AG490, a pharmacological inhibitor of Janus family tyrosine kinases (Jaks), blocked the chemotactic response of primary mouse lymphocytes to CCL19 and CCL21 in a dose-dependent manner. Furthermore, Tyr AG490 inhibited rapid CCL21-mediated up-regulation of α4 and β2 integrin adhesiveness in static adhesion assays and under physiological flow, whereas adhesion induced by phorbol myristate acetate remained unaltered. Using intravital microscopy of subiliac PLNs in mice, we found that adoptively transferred Tyr AG490–treated lymphocytes adhered significantly less in HEVs compared with control cells, although L-selectin–mediated rolling was similar in both samples. Finally, we observed rapid Jak2 phosphorylation in CCL21-stimulated primary mouse lymphocytes. Thus, our study suggests a role for Jak tyrosine kinases during CCR7-mediated lymphocyte recirculation.
Monoglycerides induce apoptosis in human leukemic cells while sparing normal peripheral blood mononuclear cells
Authors: Philippoussis Fabianne , Arguin Chantal , Mateo Véronique , Steff Ann-Muriel , Hugo Patrice 
Published: December 2002

Abstract
A major drawback of the current antineoplastic treatments is their lack of specificity toward cancer cells, because they are most often cytotoxic to normal cells, thus creating related side effects. Hence, the identification of new apoptosis-inducing agents, specifically targeting malignant cells while sparing their normal counterparts, is of crucial interest. We show here that monoglycerides, a family of lipids consisting of a single fatty acid attached to a glycerol backbone, induce cell death in several human leukemic cell lines. Importantly, treatment of primary leukemic cells, obtained from B-cell chronic lymphocytic leukemia patients, resulted in rapid apoptosis. In striking contrast, resting or activated human peripheral blood mononuclear cells from healthy individuals were resistant to the same treatment. Therefore, these compounds could represent potential antileukemic drugs or could allow for the design of novel therapeutic agents applied to leukemia.
Early macrophage influx to sites of cutaneous granuloma formation is dependent on MIP-1α/β released from neutrophils recruited by mast cell–derived TNFα
Authors: von Stebut Esther , Metz Martin , Milon Genevieve , Knop Jürgen , Maurer Marcus 
Published: December 2002

AbstractMacrophages (MΦ) play a crucial role in the development of cutaneous granulomas (CGs) initiated by foreign bodies or invasive microorganisms. However, little is known about how MΦ are recruited to sites of CG formation. To test whether mast cells (MCs) contribute to early MΦ recruitment to developing granulomas, CGs were induced in MC-deficient KitW/KitW-v mice by injection of polyacrylamide gel (PAG).KitW/KitW-v mice as well as mice deficient in the MC product TNFα exhibited markedly reduced MΦ numbers in CGs. MΦ recruitment was restored inKitW/KitW-v mice reconstituted with MCs from Kit+/+ or TNFα+/+, but not from TNFα−/− mice. MC-TNFα–dependent MΦ influx required prior recruitment of MIP-1α/β–producing neutrophils (PMNs), as PMN depletion before induction of CGs completely inhibited MΦ influx, which was restored after reconstitution with PMN supernatants. These findings indicate that MΦ recruitment to cutaneous PAG- induced granulomas is the result of a sequence of inflammatory processes initiated by MC-derived TNFα followed by PMN influx and MIP-1a/β release.
An Arg760Cys mutation in the consensus sequence of the von Willebrand factor propeptide cleavage site is responsible for a new von Willebrand disease variant
Authors: Casonato Alessandra , Sartorello Francesca , Cattini Maria Grazia , Pontara Elena , Soldera Carmen , Bertomoro Antonella , Girolami Antonio 
Published: December 2002

AbstractWe describe a von Willebrand disease (VWD) variant characterized by the persistence of von Willebrand factor (VWF) propeptide as a result of a C&gt;T transition at nucleotide 2527 in exon 17 of the VWF gene. This mutation, which was present in the proband and his father, predicts the substitution of Cys for Arg at position 760 of pre–pro-VWF, 4 residues before the propeptide cleavage site belonging to a consensus sequence for substrate recognition by the processing enzyme paired dibasic amino acid–cleaving enzyme (PACE)/furin. Sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS-PAGE) documented the presence of both processed and unprocessed VWF in the patient's plasma, with unprocessed VWF relatively less represented. The patient's hemostatic phenotype was characterized by a mild decrease in plasma factor VIII (FVIII) and VWF, a decrease in plasma VWF multimers, and a mild reduction in the FVIII binding capacity of VWF. The FVIII binding defect was more pronounced in the proband than in the father because he also inherited the type 2N Arg91Gln mutation from his mother. The persistence of VWF propeptide did not impair VWF synthesis because platelet VWF content was normal, nor did it compromise VWF storage in endothelial cells, because of the normal post–1-deamino-8-D-arginine vasopressin (DDAVP) increase in plasma VWF. Coexpression of wild-type and Arg760Cys VWF into a Furin-producing BHK cell line resulted in decreased VWF secretion and a defect in the FVIII binding capacity of VWF, together with the persistence of VWF propeptide. These findings confirm that a normal consensus sequence for VWF propeptide cleavage and efficient cleavage are required in vivo for normal FVIII binding capacity of VWF.
Essential role for ICSBP in the in vivo development of murine CD8α+ dendritic cells
Authors: Aliberti Julio , Schulz Oliver , Pennington Daniel J. , Tsujimura Hideki , Reis e Sousa Caetano , Ozato Keiko , Sher Alan 
Published: December 2002

AbstractInterferon (IFN) consensus sequence-binding protein (ICSBP) is an important transcription factor regulating proinflammatory cytokine production and the development of mononuclear phagocytes in vitro. Here we analyzed the role of ICSBP in the in vivo differentiation of 3 major subsets of murine dendritic cells (DCs). We found that ICSBP is predominantly expressed by the CD8α+ subset, and more important, that ICSBP−/− mice have a profound and selective deficiency in CD8α+ DEC205+ DCs in lymphoid tissues. Studies using wild-type/ICSBP−/−chimeras revealed that this defect in CD8α+ DC development is intrinsic to bone marrow–derived progenitors and not dependent on ICSBP expression in the nonhemopoietic compartment. Because DC precursor frequencies are unaltered in the bone marrow of ICSBP−/− mice, ICSBP appears to function by regulating CD8α+ DC differentiation downstream from the generation of common DC progenitors. Although CD8α− DCs are present in normal numbers in ICSBP−/− animals, up-regulation of CD40, CD80, and major histocompatibility complex (MHC) class II expression was found to be impaired in this subset after in vivo microbial stimulation. Together these results demonstrate that ICSBP is critically required for the in vivo differentiation of CD8α+ DCs and may also influence the functional maturation of the CD8α− subsets.
Ribosomal protein S19 expression during erythroid differentiation
Authors: Da Costa Lydie , Narla Goutham , Willig Thiébaut-Noel , Peters Luanne L. , Parra Marilyn , Fixler Jason , Tchernia Gil , Mohandas Narla 
Published: December 2002

AbstractThe gene encoding ribosomal protein S19 (RPS19) has been shown to be mutated in 25% of the patients affected by Diamond-Blackfan anemia (DBA), a congenital erythroblastopenia. As the role of RPS19 in erythropoiesis is still to be defined, we performed studies on RPS19 expression during terminal erythroid differentiation. Comparative analysis of the genomic sequences of human and mouse RPS19genes enabled the identification of 4 conserved sequence elements in the 5′ region. Characterization of transcriptional elements allowed the identification of the promoter in the human RPS19 gene and the localization of a strong regulatory element in the third conserved sequence element. By Northern blot and Western blot analyses of murine splenic erythroblasts infected with the anemia-inducing strain Friend virus (FAV cells), RPS19 mRNA and protein expression were shown to decrease during terminal erythroid differentiation. We anticipate that these findings will contribute to further development of our understanding of the contribution of RPS19 to erythropoiesis.
Interferon-γ switches monocyte differentiation from dendritic cells to macrophages
Authors: Delneste Yves , Charbonnier Peggy , Herbault Nathalie , Magistrelli Giovanni , Caron Gersende , Bonnefoy Jean-Yves , Jeannin Pascale 
Published: December 2002

AbstractHuman monocytes differentiate into dendritic cells (DCs) or macrophages according to the nature of environmental signals. Monocytes stimulated with granulocyte-macrophage colony-stimulating factor (GM-CSF) plus interleukin 4 (IL-4) yield DCs. We tested here whether interferon-γ (IFN-γ), a potent activator of macrophages, may modulate monocyte differentiation. Addition of IFN-γ to IL-4 plus GM-CSF–stimulated monocytes switches their differentiation from DCs to CD14−CD64+ macrophages. IFN-γ increases macrophage colony-stimulating factor (M-CSF) and IL-6 production by IL-4 plus GM-CSF–stimulated monocytes by acting at the transcriptional level and acts together with IL-4 to up-regulate M-CSF but not IL-6 production. IFN-γ also increases M-CSF receptor internalization. Results from neutralizing experiments show that both M-CSF and IL-6 are involved in the ability of IFN-γ to skew monocyte differentiation from DCs to macrophages. Finally, this effect of IFN-γ is limited to early stages of differentiation. When added to immature DCs, IFN-γ up-regulates IL-6 but not M-CSF production and does not convert them to macrophages, even in the presence of exogenous M-CSF. In conclusion, IFN-γ shifts monocyte differentiation to macrophages rather than DCs through autocrine M-CSF and IL-6 production. These data show that IFN-γ controls the differentiation of antigen-presenting cells and thereby reveals a new mechanism by which IFN-γ orchestrates the outcome of specific immune responses.
Centrosome aberrations in acute myeloid leukemia are correlated with cytogenetic risk profile
Authors: Neben Kai , Giesecke Christian , Schweizer Silja , Ho Anthony D. , Krämer Alwin 
Published: December 2002

Abstract
Genetic instability is a common feature in acute myeloid leukemia (AML). Centrosome aberrations have been described as a possible cause of aneuploidy in many human tumors. To investigate whether centrosome aberrations correlate with cytogenetic findings in AML, we examined a set of 51 AML samples by using a centrosome-specific antibody to pericentrin. All 51 AML samples analyzed displayed numerical and structural centrosome aberrations (36.0% ± 16.6%) as compared with peripheral blood mononuclear cells from 21 healthy volunteers (5.2% ± 2.0%; P &lt; .0001). In comparison to AML samples with normal chromosome count, the extent of numerical and structural centrosome aberrations was higher in samples with numerical chromosome changes (50.5% ± 14.2% versus 34.3% ± 12.2%; P &lt; .0001). When the frequency of centrosome aberrations was analyzed within cytogenetically defined risk groups, we found a correlation of the extent of centrosome abnormalities to all 3 risk groups (P = .0015), defined as favorable (22.5% ± 7.3%), intermediate (35.3% ± 13.1%), and adverse (50.3% ± 15.6%). These results indicate that centrosome defects may contribute to the acquisition of chromosome aberrations and thereby to the prognosis in AML.
Regulation of Akt-dependent cell survival by Syk and Rac
Authors: Jiang Kun , Zhong Bin , Ritchey Connie , Gilvary Danielle L. , Hong-Geller Elizabeth , Wei Sheng , Djeu Julie Y. 
Published: December 2002

AbstractInterleukin-2 (IL-2) prevents cell apoptosis and promotes survival, but the involved mechanisms have not been completely defined. Although phosphatidylinositide 3-kinase (PI 3-kinase) has been implicated in IL-2–mediated survival mechanisms, none of the 3 chains of the IL-2 receptor (IL-2R) expresses a binding site for PI 3-kinase. However, IL-2Rβ does express a Syk-binding motif. By using an IL-2–dependent natural killer (NK) cell line, followed by validation of the results in fresh human NK cells, we identified Syk as a critical effector essential for IL-2–mediated prosurvival signaling in NK cells. Down-regulation of Syk by piceatannol treatment impaired NK cellular viability and induced prominent apoptosis as effectively as suppression of PI 3-kinase function by LY294002. Expression of kinase-deficient Syk or pretreatment with piceatannol markedly suppressed IL-2–stimulated activation of PI 3-kinase and Akt, demonstrating that Syk is upstream of PI 3-kinase and Akt. However, constitutively active PI 3-kinase reversed this loss of Akt function caused by kinase-deficient Syk or piceatannol. Thus, Syk appears to regulate PI 3-kinase, which controls Akt activity during IL-2 stimulation. More important, we observed Rac1 activation by IL-2 and found that it mediated PI 3-kinase activation of Akt. This conclusion came from experiments in which dominant-negative Rac1 significantly decreased IL-2–induced Akt activation, whereas constitutively active Rac1 reelevated Akt activity not only in Syk-impaired but also in PI 3-kinase–impaired NK cells. These results constitute the first report of a Syk → PI3K → Rac1 → Akt signal cascade controlled by IL-2 that mediates NK cell survival.
Evidence that the red cell skeleton protein 4.2 interacts with the Rh membrane complex member CD47
Authors: Mouro-Chanteloup Isabelle , Delaunay Jean , Gane Pierre , Nicolas Virginie , Johansen Mette , Brown Eric J. , Peters Luanne L. , Le Van Kim Caroline , Cartron Jean Pierre , Colin Yves 
Published: December 2002

AbstractRhnull red cells are characteristically stomato-spherocytic. This and other evidence suggest that the Rh complex represents a major attachment site between the membrane lipid bilayer and the erythroid skeleton. As an attempt to identify the linking protein(s) between the red cell skeleton and the Rh complex, we analyzed the expression of Rh, RhAG, CD47, LW, and glycophorin B proteins in red cells from patients with hereditary spherocytosis associated with complete protein 4.2 deficiency but normal band 3 (4.2(-)HS). Flow cytometric and immunoblotting analysis revealed a severe reduction of CD47 (up to 80%) and a slower mobility of RhAG on sodium dodecyl sulfate–polyacrylamide gel electrophoresis, possibly reflecting an overglycosylation state. Unexpectedly, 4.2−/− mice, which are anemic, displayed a normal red cell expression of CD47 and RhAG. These results suggest that human protein 4.2, through interaction with CD47, is involved in the skeleton linkage and/or membrane translocation of the Rh complex. However, these potential role(s) of protein 4.2 might be not conserved across species. Finally, the absence or low expression of red cell CD47 in CD47−/− mice and in some humans carrying RHCEgene variants (D--, D.., and RN), respectively, had no detectable effect on protein 4.2 and RhAG expression. Since these cells are morphologically normal with no sign of hemolysis, it is assumed that CD47 deficiency per se is not responsible for the cell shape abnormalities and for the compensated hemolytic anemia typical of 4.2(-) and Rhnull red cells.