bluuebunny/crossref_metadata_2025_split huggingface dataset:
Role of AP1/NFE2 binding sites in endogenous α-globin gene transcription
Authors: Loyd Melanie R. , Okamoto Yasuhiro , Randall Mindy S. , Ney Paul A. 
Published: August 2003

AbstractHigh-level α-globin expression depends on cis-acting regulatory sequences located far upstream of the α-globin cluster. Sequences that contain the α-globin positive regulatory element (PRE) activate α-globin expression in transgenic mice. The α-globin PRE contains a pair of composite binding sites for the transcription factors activating protein 1 and nuclear factor erythroid 2 (AP1/NFE2). To determine the role of these binding sites in α-globin gene transcription, we mutated the AP1/NFE2 sites in the α-globin PRE in mice. We replaced the AP1/NFE2 sites with a neomycin resistance gene (neo) that is flanked by LoxP sites (floxed). Mice with this mutation exhibited increased embryonic death and α-thalassemia intermedia. Next, we removed the neo gene by Cre-mediated recombination, leaving a single LoxP site in place of the AP1/NFE2 sites. These mice were phenotypically normal. However, α-globin expression, measured by allele-specific RNA polymerase chain reaction (PCR), was decreased 25%. We examined the role of the hematopoietic-restricted transcription factor p45Nfe2 in activating expression through these sites and found that it is not required. Thus, we have demonstrated that AP1/NFE2 binding sites in the murine α-globin PRE contribute to long-range α-globin gene activation. The proteins that mediate this effect remain to be determined. (Blood. 2003;102:4223-4228)
Farnesyltransferase inhibitors in hematologic malignancies: new horizons in therapy
Authors: Lancet Jeffrey E. , Karp Judith E. 
Published: August 2003

AbstractFarnesyltransferase inhibitors (FTIs) are small-molecule inhibitors that selectively inhibit farnesylation of a number of intracellular substrate proteins such as Ras. Preclinical work has revealed their ability to effectively inhibit tumor growth across a wide range of malignant phenotypes. Many hematologic malignancies appear to be reasonable disease targets, in that they express relevant biologic targets, such as Ras, mitogen-activated protein kinase (MAPK), AKT, and others that may depend on farnesyl protein transferase (FTase) activity to promote proliferation and survival. A host of phase 1 trials have been recently launched to assess the applicability of FTIs in hematologic malignancies, many of which demonstrate effective enzyme target inhibition, low toxicity, and some clinical responses. As a result, phase 2 trials have been initiated in a variety of hematologic malignancies and disease settings to further validate clinical activity and to identify downstream signal transduction targets that may be modified by these agents. It is anticipated that these studies will serve to define the optimal roles of FTIs in patients with hematologic malignancies and provide insight into effective methods by which to combine FTIs with other agents.
Matrix-fibrinogen enhances wound closure by increasing both cell proliferation and migration
Authors: Rybarczyk Brian J. , Lawrence Sarah O. , Simpson-Haidaris Patricia J. 
Published: August 2003

AbstractFibrinogen (FBG) assembles into matrix fibrils of fibroblasts, lung and mammary epithelial cells, but not endothelial cells. Furthermore, cryptic β15-21 residues are exposed in FBG fibrils with no evidence of thrombin or plasmin proteolysis. Herein, the effects of FBG on migration and proliferation of wounded dermal fibroblasts were investigated. FBG preassembled into matrix prior to scrape-wounding induced 3H-thymidine incorporation 8-fold and shortened the time to wound closure 1.6-fold ± 0.1-fold. FBG added immediately after wounding did not enhance either response. Fibroblast growth factor-2/platelet-derived growth factor (FGF-2/PDGF) stimulated cell proliferation 2.2-fold for FGF-2 and 3.2-fold for PDGF and wound closure 1.5-fold ± 0.1-fold in the absence of matrix-FBG. Surprisingly, exogenous growth factors had negligible effect on wound closure and cell proliferation already enhanced by matrix-FBG. Matrix-FBG-enhanced wound closure required active assembly of an FBG-fibronectin matrix, engagement of αvβ3, and FBG Aα-RGDS572-575 integrin recognition sites; Aα-RGDF95-98 sites were not sufficient for matrix-FBG assembly, enhanced wound closure, or cell proliferation. Although Bβ1-42 was not necessary for matrix assembly, it was required for matrix-FBG-enhanced cell migration. These data indicate that FBG serves as an important matrix constituent in the absence of fibrin formation to enhance wound repair and implicate Bβ1-42 as a physiologic inducer of signal transduction to promote an intermediate state of cell adhesion and a migratory cell phenotype. (Blood. 2003;102:4035-4043)
Proteasomal targeting of a viral oncogene abrogates oncogenic phenotype and enhances immunogenicity
Authors: Tellam Judy , Connolly Geoff , Webb Natasha , Duraiswamy Jaikumar , Khanna Rajiv 
Published: August 2003

AbstractThe ability of viral or mutated cellular oncogenes to initiate neoplastic events and their poor immunogenicity have considerably undermined their potential use as immunotherapeutic tools for the treatment of human cancers. Using an Epstein-Barr virus-encoded oncogene, latent membrane protein 1 (LMP1), as a model, we report a novel strategy that both deactivates cellular signaling pathways associated with the oncogenic phenotype and reverses poor immunogenicity. We show that cotranslational ubiquitination combined with N-end rule targeting of LMP1 enhanced the intracellular degradation of LMP1 and total blockade of LMP1-mediated nuclear factor-κB (NF-κB) and signal transducer and activator of transcription (STAT) activation in human cells. In addition, although murine cells expressing LMP1 were uniformly tumorigenic, this oncogenicity was completely abrogated by covalent linkage of LMP1 with ubiquitin, while an enhanced CD8+ T cell response to a model epitope fused to the C-terminus of LMP1 was observed following immunization with ubiquitinated LMP1. These observations suggest that proteasomal targeting of tumor-associated oncogenes could be exploited therapeutically by either gene therapy or vaccination. (Blood. 2003;102:4535-4540)
Activation of interleukin-13 expression in T cells from HTLV-1-infected individuals and in chronically infected cell lines
Authors: Chung Hye-Kyung , Young Howard A. , Goon Peter K. C. , Heidecker Gisela , Princler Gerald L. , Shimozato Osamu , Taylor Graham P. , Bangham Charles R. M. , Derse David 
Published: August 2003

AbstractHuman T-cell leukemia virus type 1 (HTLV-1) infection profoundly alters T-cell gene expression, and the dysregulated synthesis of cytokines could influence the course and pathologic consequences of infection. In the process of screening T-cell lines for T helper 1 (Th1) and Th2 cytokine mRNAs, we observed that interleukin-13 (IL-13) mRNA was highly expressed in HTLV-1-infected, IL-2-dependent T-cell lines. IL-9 and interferon gamma (IFN-γ) mRNAs were also expressed at high levels in chronically infected cell lines. IL-5 mRNA was detected in 60% of the HTLV-1-infected cell lines, but mRNAs for IL-4, IL-10, IL-2, and IL-15 were either below detection limits or did not correlate with HTLV-1 infection. Transcriptional activation of the IL-13 promoter by the HTLV-1 Tax trans-regulatory protein was demonstrated in Jurkat T cells transiently transfected with an IL-13 promoter-reporter plasmid. The clinical relevance of these observations was demonstrated by immunofluorescent staining and flow cytometry of lymphocytes obtained from HTLV-1-infected patients. These studies revealed that IL-13 production was directly related to the level of Tax expression in the infected CD4+ T cells soon after in vitro culture. As IL-13 plays key roles in tumor immunosurveillance, asthma, and central nervous system inflammation, it may contribute to the pathophysiology of HTLV-1-associated diseases. (Blood. 2003;102:4130-4136)
Regulation of tissue factor cytoplasmic domain phosphorylation by palmitoylation
Authors: Dorfleutner Andrea , Ruf Wolfram 
Published: August 2003

AbstractThe tissue factor (TF)–initiated coagulation pathway plays important roles in hemostasis, inflammation, metastasis, and angiogenesis. Phosphorylation of the TF cytoplasmic domain is functionally relevant in metastasis. How TF cytoplasmic domain phosphorylation downstream of protein kinase C (PKC) activation is regulated in primary vascular cells remains poorly understood. Here, phosphorylation of Ser258, rather than the PKC consensus site Ser253, is identified as the major conformational switch required for recognition by a phosphorylation-specific antibody. With this novel reagent, we demonstrate that the TF cytoplasmic domain is primarily unphosphorylated in confluent endothelial cells. TF cytoplasmic domain phosphorylation can occur in the absence of the autologous TF transmembrane and extracellular domains but requires maturation of TF in the Golgi compartment and cell surface expression. Site-directed mutagenesis and 2-bromopalmitate treatment provide evidence that palmitoylation of the cytoplasmic Cys245 is a negative regulatory mechanism of Ser258 phosphorylation. Profiling with PKC-selective inhibitors identifies PKCα as important for TF cytoplasmic domain phosphorylation. Mutagenesis of protein kinase consensus sites are consistent with a model in which PKC-dependent phosphorylation of Ser253 enhances subsequent Ser258 phosphorylation by a Pro-directed kinase. Thus, cell surface location–dependent phosphorylation of the TF cytoplasmic domain is regulated at multiple levels.
PTP-MEG2 is activated in polycythemia vera erythroid progenitor cells and is required for growth and expansion of erythroid cells
Authors: Xu Ming-jiang , Sui Xingwei , Zhao Runxiang , Dai Chunhua , Krantz Sanford B. , Zhao Zhizhuang Joe 
Published: August 2003

AbstractPolycythemia vera (PV) is a human clonal hematologic disorder. Previously we demonstrated that erythroid colony-forming cells (ECFCs) from PV patients contained a hyperactive membrane-associated tyrosine phosphatase. We now show that this phosphatase corresponded to protein tyrosine phosphatase (PTP)-MEG2, an intracellular enzyme with a putative lipid-binding domain. The increased activity of PTP-MEG2 in PV cells is due to its elevated distribution in the membrane fraction. With the development of ECFCs to mature red cells, the protein level of PTP-MEG2 decreased gradually, but membrane-associated PTP-MEG2 was sustained for a longer period of time in PV cells, which correlated with an enhanced colony-forming capability of the cells. Importantly, expression of dominant-negative mutant forms of PTP-MEG2 suppressed in vitro growth and expansion of both normal and PV ECFCs. The data indicate that PTP-MEG2 has an important role in the development of erythroid cells. (Blood. 2003;102:4354-4360)
Developmental stage–specific epigenetic control of human β-globin gene expression is potentiated in hematopoietic progenitor cells prior to their transcriptional activation
Authors: Bottardi Stefania , Aumont Angélique , Grosveld Frank , Milot Eric 
Published: August 2003

AbstractTo study epigenetic regulation of the human β-globin locus during hematopoiesis, we investigated patterns of histone modification and chromatin accessibility along this locus in hematopoietic progenitor cells (HPCs) derived from both humans and transgenic mice. We demonstrate that the developmentally related activation of human β-like globin genes in humans and transgenic mice HPCs is preceded by a wave of gene-specific histone H3 hyperacetylation and K4 dimethylation. In erythroid cells, expression of β-like globin genes is associated with histone hyperacetylation along these genes and, surprisingly, with local deacetylation at active promoters. We also show that endogenous mouse β major and human β-like genes are subject to different epigenetic control mechanisms in HPCs. This difference is likely due to intrinsic properties of the human β-globin locus since, in transgenic mice, this locus is epigenetically regulated in the same manner as in human HPCs. Our results suggest that a defined pattern of histone H3 acetylation/dimethylation is important for specific activation of human globin promoters during development in human and transgenic HPCs. We propose that this transient acetylation/dimethylation is involved in gene-specific potentiation in HPCs (ie, before extensive chromatin remodeling and transcription take place in erythroid cells).
BMP4 acts upstream of FGF in modulating thymic stroma and regulating thymopoiesis
Authors: Tsai Peter T. , Lee Robert A. , Wu Hong 
Published: August 2003

AbstractThymocyte development is a non–cell-autonomous process that requires signals provided by the thymic stroma. Bone morphogenetic proteins (BMPs) and fibroblast growth factors (FGFs) derived from thymic stroma have been implicated as possible regulators of T-cell development. Using thymic organ culture, this study demonstrates that both BMP4 and FGF7/FGF10 arrest early T-cell development at the CD4-CD8-CD44+CD25- (double-negative 1 [DN1]) population and at the CD4-CD8- double-negative (DN) to CD4+CD8+ double-positive (DP) transition in a stromal compartment–dependent manner. Furthermore, BMP4 functions upstream of FGF7/FGF10, as the effects of BMP can be suppressed by cotreatment with an FGF receptor antagonist. BMP4 also acts directly on the thymic stroma to up-regulate the stroma-specific transcription factor Foxn1 and stroma-expressed chemokines. Taken together, the data in this report demonstrate that BMP acts upstream of FGF in the regulation of early T-cell development and that BMP4 acts primarily through the thymic stroma, thereby altering the thymic microenvironment and affecting thymopoiesis.
Specific abrogation of transforming growth factor-β signaling in T cells alters atherosclerotic lesion size and composition in mice
Authors: Gojova Andrea , Brun Valérie , Esposito Bruno , Cottrez Françoise , Gourdy Pierre , Ardouin Patrice , Tedgui Alain , Mallat Ziad , Groux Hervé 
Published: August 2003

Abstract
A large body of evidence supports a role for proinflammatory mediators in atherosclerotic disease progression and instability. However, only few endogenous mechanisms have been suggested that could alter disease progression. One such mechanism is thought to be mediated by transforming growth factor β (TGF-β). Transgenic mice that express a dominant-negative TGF-β receptor type II under a T-cell-specific promoter were generated. Bone marrow transplantation from transgenic mice into irradiated low density lipoprotein receptor knock-out (LDLr KO) mice, subsequently fed an atherogenic diet, resulted in T-cell-specific blockade of TGF-β signaling in the recipient mice and increased differentiation of T cells toward both T helper 1 (Th1) and Th2 phenotypes. These mice showed a significant decrease in atherosclerotic lesion size in the aortic sinus compared with mice receiving transplants with the wild-type bone marrow. Atherosclerotic plaques of mice receiving transplants with the transgenic bone marrow showed increased T-cell infiltration and expression of major histocompatability complex (MHC) class II, along with a decrease in smooth muscle cell and collagen content, a plaque phenotype that is potentially vulnerable to rupture. These results identify for the first time an important role for specific and selective T-cell-TGF-β signaling in atherosclerosis. (Blood. 2003;102:4052-4058)
Production of functional platelets by differentiated embryonic stem (ES) cells in vitro
Authors: Fujimoto Tetsuro-Takahiro , Kohata Satoshi , Suzuki Hidenori , Miyazaki Hiroshi , Fujimura Kingo 
Published: August 2003

AbstractMegakaryocytes and functional platelets were generated in vitro from murine embryonic stem (ES) cells with the use of a coculture system with stromal cells. Two morphologically distinctive megakaryocytes were observed sequentially. Small megakaryocytes rapidly produced proplatelets on day 8 of the differentiation, and large hyperploid megakaryocytes developed after day 12, suggesting primitive and definitive megakaryopoiesis. Two waves of platelet production were consistently observed in the culture medium. A larger number of platelets was produced in the second wave; 104 ES cells produced up to 108 platelets. By transmission electron microscopy, platelets from the first wave were relatively rounder with a limited number of granules, but platelets from the second wave were discoid shaped with well-developed granules that were indistinguishable from peripheral blood platelets. ES-derived platelets were functional since they bound fibrinogen, formed aggregates, expressed P-selectin upon stimulation, and fully spread on immobilized fibrinogen. These results show the potential utility of ES-derived platelets for clinical applications. Furthermore, production of gene-transferred platelets was achieved by differentiating ES cells that were transfected with genes of interest. Overexpression of the cytoplasmic domain of integrin β3 in the ES-derived platelets prevented the activation of αIIbβ3, demonstrating that this system will facilitate functional platelet studies. (Blood. 2003;102:4044-4051)
Distribution of plasma membrane Ca2+ pump activity in normal human red blood cells
Authors: Lew Virgilio L. , Daw Nuala , Perdomo Deisy , Etzion Zipora , Bookchin Robert M. , Tiffert Teresa 
Published: August 2003

AbstractThe plasma membrane calcium pump (PMCA) is the only active Ca2+ transporter in human red blood cells (RBCs). Previous measurements of maximal Ca2+ extrusion rates (Vmax) reported only mean values in the RBC population. Despite early evidence for differences in Ca2+ extrusion capacity among RBCs, the precise Vmax distribution remained unknown. It was important to characterize this distribution to assess the range and modality (uni- or multimodal) of PMCA Vmax variation and the likelihood of RBCs with elevated [Ca2+]i in the circulation participating in physiologic and pathologic processes. We report here the application of a new method to investigate the detailed distribution of PMCA Vmax activity in RBCs. The migrating profile of osmotic lysis curves was used to identify and quantify the fraction of cells that extrude a uniform Ca2+ load at different rates. The results revealed that RBCs from single donors have large variations in PMCA activity that follow a unimodal, broad distribution pattern consistently skewed toward higher Vmax values, suggesting an excess of cells with Vmax higher than the mean value. The method applied may provide a way of evaluating whether the observed variation in PMCA Vmax is related to cell age. (Blood. 2003;102:4206-4213)
Allogeneic hematopoietic stem cell transplantation for myelofibrosis
Authors: Deeg H. Joachim , Gooley Theodore A. , Flowers Mary E. D. , Sale George E. , Slattery John T. , Anasetti Claudio , Chauncey Thomas R. , Doney Kristine , Georges George E. , Kiem Hans-Peter , Martin Paul J. , Petersdorf Effie W. , Radich Jerald , Sanders Jean E. , Sandmaier Brenda M. , Warren E. Houston , Witherspoon Robert P. , Storb Rainer , Appelbaum Frederick R. 
Published: August 2003

Abstract
Fifty-six patients, 10 to 66 years of age, with idiopathic myelofibrosis (IMF) or end-stage polycythemia vera or essential thrombocythemia received allogeneic hematopoietic cell transplants from related (n = 36) or unrelated (n = 20) donors. Forty-four patients were prepared with busulfan plus cyclophosphamide and 12 with total body irradiation plus chemotherapy. The source of stem cells was marrow in 33 and peripheral blood in 23 patients. All but 3 patients achieved engraftment. While 50 patients showed complete donor chimerism, 3 patients were found to be mixed chimeras at 26, 48, and 86 months after transplantation, respectively. Two patients died from relapse/progressive disease, and 18 died from other causes. There are 36 patients surviving at 0.5 to 11.6 (median, 2.8) years, for a 3-year Kaplan-Meier estimate of 58% (CI, 43%-73%). Dupriez score, cytogenetic abnormalities, and degree of marrow fibrosis were the most significant risk factors for posttransplantation mortality. Patients conditioned with a regimen of busulfan targeted to plasma levels of 800 to 900 ng/mL plus cyclophosphamide had a higher probability of survival (76% [CI, 62%-91%]) than other patients. Results with unrelated donors were comparable with those with HLA-identical sibling transplants. Thus, allogeneic hematopoietic cell transplantation offers long-term relapse-free survival for patients with myelofibrosis.
Inhibition of invariant chain expression in dendritic cells presenting endogenous antigens stimulates CD4+ T-cell responses and tumor immunity
Authors: Zhao Yangbing , Boczkowski David , Nair Smita K. , Gilboa Eli 
Published: August 2003

AbstractInduction of potent and sustained antiviral or antitumor immunity is dependent on the efficient activation of CD8+ and CD4+ T cells. While dendritic cells constitute a powerful platform for stimulating cellular immunity, presentation of endogenous antigens by dendritic cells transfected with nucleic acid-encoded antigens favors the stimulation of CD8+ T cells over that of CD4+ T cells. A short incubation of mRNA-transfected dendritic cells with antisense oligonucleotides directed against the invariant chain enhances the presentation of mRNA-encoded class II epitopes and activation of CD4+ T-cell responses in vitro and in vivo. Immunization of mice with the antisense oligonucleotide-treated dendritic cells stimulates a more potent and longer lasting CD8+ cytotoxic T-cell (CTL) response and enhances the antitumor efficacy of dendritic cell-based tumor vaccination protocols. Transient inhibition of invariant chain expression represents a simple and general method to enhance the stimulation of CD4+ T-cell responses from endogenous antigens. (Blood. 2003;102:4137-4142)
The phosphoserine-585–dependent pathway of the GM-CSF/IL-3/IL-5 receptors mediates hematopoietic cell survival through activation of NF-κB and induction of bcl-2
Authors: Guthridge Mark A. , Barry Emma F. , Felquer Fernando A. , McClure Barbara J. , Stomski Frank C. , Ramshaw Hayley , Lopez Angel F. 
Published: August 2003

AbstractWe have recently identified a novel mechanism of hematopoietic cell survival that involves site-specific serine phosphorylation of the common beta subunit (βc) of the granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin-3 (IL-3), and IL-5 receptors. However, the downstream components of this pathway are not known, nor is its relationship to survival signals triggered by tyrosine phosphorylation of the receptor clear. We have now found that phosphorylation of Ser585 of βc in response to GM-CSF recruited 14-3-3 and phosphatidyl inositol 3-OH kinase (PI 3-kinase) to the receptor, while phosphorylation of the neighboring Tyr577 within this “viability domain” promoted the activation of both Src homology and collagen (Shc) and Ras. These are independent processes as demonstrated by the intact reactivity of phosphospecific anti-Ser585 and anti-Tyr577 antibodies on the cytotoxic T-lymphocyte–ecotrophic retroviral receptor neomycin (CTL-EN) mutants βcTyr577Phe and βcSer585Gly, respectively. Importantly, while mutants in which either Ser585 (βcSer585Gly) or all tyrosines (βcF8) were substituted showed a defect in Akt phosphorylation, nuclear factor κB (NF-κB) activation, bcl-2 induction, and cell survival, the mutant βcTyr577Phe was defective in Shc, Ras, and extracellular signal-related kinase (ERK) activation, but supported CTL-EN cell survival in response to GM-CSF. These results demonstrate that both serine and tyrosine phosphorylation pathways play a role in hematopoietic cell survival, are initially independent of each other, and converge on NF-κB to promote bcl-2 expression.