bluuebunny/crossref_metadata_2025_split huggingface dataset:
Involvement of ABC7 in the biosynthesis of heme in erythroid cells: interaction of ABC7 with ferrochelatase
Authors: Taketani Shigeru , Kakimoto Kazuhiro , Ueta Hiromi , Masaki Ryuichi , Furukawa Takako 
Published: April 2003

AbstractA mitochondrial half-type ATP-binding cassette (ABC) protein, ABC7, plays a role in iron homeostasis in mitochondria, and defects in human ABC7 were shown to be responsible for the inherited disease X-linked sideroblastic anemia/ataxia. We examined the role of ABC7 in the biosynthesis of heme in erythroid cells where hemoglobin is a major product of iron-containing compounds. RNA blots showed that the amount of ABC7 mRNA in dimethylsulfoxide (Me2SO)-treated mouse erythroleukemia (MEL) cells increased markedly in parallel with the induction of the mRNA expression of ferrochelatase, the last enzyme in the pathway to synthesize heme. The transfection of the antisense oligonucleotide to mouse ABC7 mRNA into Me2SO-treated MEL cells led to a decrease of heme production, as compared with sense oligonucleotide–transfected cells. ABC7 protein was shown to be colocalized with ferrochelatase in mitochondria, as assessed by immunostaining. Furthermore, in vitro and in vivo pull-down assays revealed that ABC7 protein is interacted with the carboxy-terminal region containing the iron-sulfur cluster of ferrochelatase. The transient expression of ABC7 in mouse embryo liver BNL-CL2 cells resulted in an increase in the activity and level of ferrochelatase and thioredoxin, a cytosolic protein containing iron-sulfur. These increases were also observed in MEL cells stably expressing ABC7. When ABC7 transfectants were treated with Me2SO, an increase in cellular heme concomitant with a marked induction of the expression of ferrochelatase was observed. The extent of these increases was 3-fold greater than in control cells. The results indicated that ABC7 positively regulates not only the expression of extramitochondrial thioredoxin but also that of an intramitochondrial iron-sulfur–containing protein, ferrochelatase. Then, the expression of ABC7 contributes to the production of heme during the differentiation of erythroid cells.
Factors affecting antibody levels after allogeneic hematopoietic cell transplantation
Authors: Storek Jan , Viganego Federico , Dawson Monja A. , Herremans M. M. P. Tineke , Boeckh Michael , Flowers Mary E. D. , Storer Barry , Bensinger William I. , Witherspoon Robert P. , Maloney David G. 
Published: April 2003

AbstractTo obtain insight into the mechanism(s) of posttransplantation humoral immunodeficiency, we evaluated factors affecting serum antibody levels against polio, tetanus, Haemophilus influenzae, andStreptococcus pneumoniae in 87 patients. Patients with hematologic malignancies were randomized to receive marrow versus blood stem cells, which contain approximately 10 times more lymphocytes than marrow. Blood stem cell recipients did not have higher antibody levels than marrow recipients. Recipient pretransplantation antibody levels were correlated with the posttransplantation levels, especially in the first 6 months after transplantation when the correlation coefficients typically exceeded 0.6. Donor pretransplantation antibody levels had less of a correlation with posttransplantation levels in the recipient. Patient or donor age, total body irradiation, and graft-versus-host disease or its treatment appeared to have no effect. In conclusion, antibody levels in the first year after transplantation are affected primarily by pretransplantation antibody levels in the recipient and, to a lesser degree, in the donor. These findings suggest that immunization of the recipient and the donor before transplantation may be more effective in improving antibody immunity after transplantation than manipulating graft-versus-host disease, changing conditioning, or increasing the number of lymphocytes in the graft.
Prenatal and postnatal myeloid cells demonstrate stepwise progression in the pathogenesis of MLL fusion gene leukemia
Authors: Johnson Jennifer J. , Chen Weili , Hudson Wendy , Yao Qing , Taylor Marnie , Rabbitts Terence H. , Kersey John H. 
Published: April 2003

Abstract
The steps to leukemia following an in utero fusion ofMLL (HRX, ALL-1) to a partner gene in humans are not known. Introduction of the Mll-AF9 fusion gene into embryonic stem cells results in leukemia in mice with cell-type specificity similar to humans. In this study we used myeloid colony assays, immunophenotyping, and transplantation to evaluate myelopoiesis in Mll-AF9 mice. Colony assays demonstrated that both prenatal and postnatal Mll-AF9 tissues have significantly increased numbers of CD11b+/CD117+/Gr-1+/− myeloid cells, often in compact clusters. The self-renewal capacity of prenatal myeloid progenitors was found to decrease following serial replating of colony-forming cells. In contrast, early postnatal myeloid progenitors increased following replating; however, the enhanced self-renewal of early postnatal myeloid progenitor cells was limited and did not result in long-term cell lines or leukemia in vivo. Unlimited replating, long-term CD11b/Gr-1+ myeloid cell lines, and the ability to produce early leukemia in vivo in transplantation experiments, were found only in mice with overt leukemia. Prenatal Mll-AF9tissues had reduced total (mature and progenitor) CD11b/Gr-1+ cells compared with wild-type tissues. Colony replating, immunophenotyping, and cytochemistry suggest that any perturbation of cellular differentiation from the prenatal stage onward is partial and largely reversible. We describe a novel informative in vitro and in vivo model system that permits study of the stages in the pathogenesis of Mll fusion gene leukemia, beginning in prenatal myeloid cells, progressing to a second stage in the postnatal period and, finally, resulting in overt leukemia in adult animals.
AML1/MTG8 oncogene suppression by small interfering RNAs supports myeloid differentiation of t(8;21)-positive leukemic cells
Authors: Heidenreich Olaf , Krauter Jürgen , Riehle Heidemarie , Hadwiger Philipp , John Matthias , Heil Gerhard , Vornlocher Hans-Peter , Nordheim Alfred 
Published: April 2003

Abstract
The translocation t(8;21) yields the leukemic fusion gene AML1/MTG8 and is associated with 10%-15% of all de novo cases of acute myeloid leukemia. We demonstrate the efficient and specific suppression of AML1/MTG8 by small interfering RNAs (siRNAs) in the human leukemic cell lines Kasumi-1 and SKNO-1. siRNAs targeted against the fusion site of the AML1/MTG8 mRNA reduce the levels of AML1/MTG8 without affecting the amount of wild-type AML1. These data argue against a transitive RNA interference mechanism potentially induced by siRNAs in such leukemic cells. Depletion of AML1/MTG8 correlates with an increased susceptibility of both Kasumi-1 and SKNO-1 cells to tumor growth factor β1 (TGFβ1)/vitamin D3–induced differentiation, leading to increased expression of CD11b, macrophage colony-stimulating factor (M-CSF) receptor, and C/EBPα (CAAT/enhancer binding protein). Moreover, siRNA-mediated AML1/MTG8 suppression results in changes in cell shape and, in combination with TGFβ1/vitamin D3, severely reduces clonogenicity of Kasumi-1 cells. These results suggest an important role for AML1/MTG8 in preventing differentiation, thereby propagating leukemic blast cells. Therefore, siRNAs are promising tools for a functional analysis of AML1/MTG8 and may be used in a molecularly defined therapeutic approach for t(8;21)-positive leukemia.
JunB gene expression is inactivated by methylation in chronic myeloid leukemia
Authors: Yang Ming-Yu , Liu Ta-Chih , Chang Jan-Gowth , Lin Pai-Mei , Lin Sheng-Fung 
Published: April 2003

AbstractJunB is a component of the Jun family genes of the activating protein-1 transcription factors that are important in the control of cell growth and differentiation and neoplastic transformation. Recently, it was demonstrated that transgenic mice specifically lacking JunB expression in the myeloid lineage developed a myeloproliferative disease, eventually progressing to blast crisis that resembled human chronic myeloid leukemia (CML). To gain further insights into the role of JunB in human CML, we examined peripheral blood from 17 healthy individuals and CML patients (11 in blastic crisis and 21 in chronic phase) by real-time quantitative reverse transcription–polymerase chain reaction analysis for the expression of JunB. The results showed the expression levels of JunB were significantly impaired in CML cases (blastic crisis < chronic phase < normal). Mutational analysis of the whole gene and methylation analysis of cytosine-phosphate guanosine (CpG) sites at the promoter area were further performed to investigate the possible mechanisms. However, no mutation was found within the coding region or the 9 flanking evolutionarily conserved regions in all CML cases. Interestingly, in the promoter area of JunB gene, most of the CpG sites were methylated in CML cases; in contrast, none of these CpG sites were methylated in normal cases. Demethylation by treatment of hypermethylated K562 cells with 5′-aza-2′-deoxycytidine resulted in partial reactivation of JunB expression. Our results suggest that the down-regulated JunB expression in CML was due to the inactivation of JunB gene by methylation and the differential expression was correlated to the ratio of cells being methylated.
Suppression of myeloid transcription factors and induction of STAT response genes by AML-specific Flt3 mutations
Authors: Mizuki Masao , Schwäble Joachim , Steur Claudia , Choudhary Chunaram , Agrawal Shuchi , Sargin Bülent , Steffen Björn , Matsumura Itaru , Kanakura Yuzuru , Böhmer Frank D. , Müller-Tidow Carsten , Berdel Wolfgang E. , Serve Hubert 
Published: April 2003

Abstract
The receptor tyrosine kinase Flt3 is expressed and functionally important in early myeloid progenitor cells and in the majority of acute myeloid leukemia (AML) blasts. Internal tandem duplications (ITDs) in the juxtamembrane domain of the receptor occur in 25% of AML cases. Previously, we have shown that these mutations activate the receptor and induce leukemic transformation. In this study, we performed genome-wide parallel expression analyses of 32Dcl3 cells stably transfected with either wild-type or 3 different ITD isoforms of Flt3. Comparison of microarray expression analyses revealed that 767 of 6586 genes differed in expression between FLT3-WT– and FLT3-ITD–expressing cell lines. The target genes of mutationally activated Flt3 resembled more closely those of the interleukin 3 (IL-3) receptor than those of ligand-activated Flt3. The serine-threonine kinase Pim-2 was up-regulated on the mRNA and the protein level in Flt3-ITD–expressing cells. Further experiments indicated that Pim-2 function was important for clonal growth of 32D cells. Several genes repressed by the mutations were found to be involved in myeloid gene regulation. Pu.1 and C/EBPα, both induced by ligand-activation of wild-type Flt3, were suppressed in their expression and function by the Flt3 mutations. In conclusion, internal tandem duplication mutations of Flt3 activate transcriptional programs that partially mimic IL-3 activity. Interestingly, other parts of the transcriptional program involve novel, IL-3–independent pathways that antagonize differentiation-inducing effects of wild-type Flt3. The identification of the transcriptional program induced by ITD mutations should ease the development of specific therapies.
Intravenous immunoglobulins induce the in vitro differentiation of human B lymphocytes and the secretion of IgG
Authors: de Grandmont Marie Joëlle , Racine Claudia , Roy Annie , Lemieux Réal , Néron Sonia 
Published: April 2003

AbstractThe therapeutic effects of intravenous immunoglobulins (IVIGs) in several autoimmune diseases are characterized by a decrease in pathologic autoantibody levels. Although little direct evidence has been reported in humans, the large repertoire of natural immunoglobulin G (IgG) antibodies in IVIGs is expected to be involved in the regulation of autoreactive B lymphocytes. In normal adult mice, IVIGs have been reported to modulate immature B cells as well as peripheral B lymphocytes through V-region connections. Studies with human serum also indicated that anti-idiotypic antibodies, present in IVIG preparations, could recognize both natural and pathologic autoantibodies. We have used an in vitro culture system to characterize the direct effect of IVIGs on human B lymphocytes. This in vitro culture system involves CD40 activation of B lymphocytes by its ligand CD154 in the presence of cytokines. In this system, addition of IVIGs decreased by 50% to 80% the expansion of B lymphocytes. This reduced expansion was due to a decrease in the proliferation rate. In addition, a portion of B lymphocytes was differentiated into IgG-secreting cells in the presence of IVIGs and the secreted IgGs were reactive with antigens such as nucleoprotamine, dsDNA, tetanus toxin, and human IgG F(ab′)2 fragments. These observations indicate that IVIGs can have direct effects on B lymphocytes and suggest that such IVIG regulation of B lymphocytes could be involved in the therapeutic effects of IVIGs in autoimmune diseases.
A model of APL with FLT3 mutation is responsive to retinoic acid and a receptor tyrosine kinase inhibitor, SU11657
Authors: Sohal Jastinder , Phan Vernon T. , Chan Philip V. , Davis Elizabeth M. , Patel Bhumi , Kelly Louise M. , Abrams Tinya J. , O'Farrell Anne Marie , Gilliland D. Gary , Le Beau Michelle M. , Kogan Scott C. 
Published: April 2003

Abstract
The PML-RARα fusion protein is central to the pathogenesis of acute promyelocytic leukemia (APL). Expression of this protein in transgenic mice initiates myeloid leukemias with features of human APL, but only after a long latency (8.5 months in MRP8 PML-RARAmice). Thus, additional changes contribute to leukemic transformation. Activating mutations of the FLT3 receptor tyrosine kinase are common in human acute myeloid leukemias and are frequent in human APL. To assess how activating mutations of FLT3 contribute to APL pathogenesis and impact therapy, we used retroviral transduction to introduce an activated allele of FLT3 into control and MRP8 PML-RARA transgenic bone marrow. Activated FLT3 cooperated with PML-RARα to induce leukemias in 62 to 299 days (median latency, 105 days). In contrast to the leukemias that arose spontaneously inMRP8 PML-RARA mice, the activated FLT3/PML-RARα leukemias were characterized by leukocytosis, similar to human APL with FLT3 mutations. Cytogenetic analysis revealed clonal karyotypic abnormalities, which may contribute to pathogenesis or progression. SU11657, a selective, oral, multitargeted tyrosine kinase inhibitor that targets FLT3, cooperated with all-trans retinoic acid to rapidly cause regression of leukemia. Our results suggest that the acquisition of FLT3 mutations by cells with a pre-existing t(15;17) is a frequent pathway to the development of APL. Our findings also indicate that APL patients with FLT3 mutations may benefit from combination therapy with all-trans retinoic acid plus an FLT3 inhibitor.
Mesenchymal stem cells distribute to a wide range of tissues following systemic infusion into nonhuman primates
Authors: Devine Steven M. , Cobbs Carrington , Jennings Matt , Bartholomew Amelia , Hoffman Ron 
Published: April 2003

Abstract
Ex vivo–expanded mesenchymal stem cells (MSCs) were transduced with a green fluorescent protein (GFP) retroviral construct and subsequently infused into 3 adult baboons following lethal total body irradiation and hematopoietic support or without any prior conditioning. To study the long-term fate of these MSCs, necropsies were performed between 9 and 21 months following MSC infusion, and an average of 16 distinct tissues were recovered from each recipient and evaluated for the presence of the GFP transgene in purified genomic DNA by sensitive real-time polymerase chain reaction (PCR). Two baboons received autologous and one allogeneic GFP-transduced MSCs. Both allogeneic and autologous MSCs appeared to distribute in a similar manner. Gastrointestinal tissues harbored high concentrations of transgene per microgram of DNA. Additional tissues including kidney, lung, liver, thymus, and skin were also found to contain relatively high amounts of DNA equivalents. Estimated levels of engraftment in these tissues ranged from 0.1% to 2.7%. The nonconditioned recipient appeared to have less abundant engraftment. These data suggest that MSCs initially distribute broadly following systemic infusion and later may participate in ongoing cellular turnover and replacement in a wide variety of tissues.
A highly sensitive strategy for SCID-repopulating cell assay by direct injection of primitive human hematopoietic cells into NOD/SCID mice bone marrow
Authors: Yahata Takashi , Ando Kiyoshi , Sato Tadayuki , Miyatake Hiroko , Nakamura Yoshihiko , Muguruma Yukari , Kato Shunichi , Hotta Tomomitsu 
Published: April 2003

AbstractTo measure the ability of human hematopoietic stem cells (HSCs), the SCID-repopulating cell (SRC) assay has been widely used. Conventionally, human HSCs are transplanted into a nonobese diabetic/severe combined immunodeficient (NOD/SCID) mouse via a tail vein. However, those cells must go through various obstacles until they reach the mouse marrow environment, which could explain the generally low homing efficiency in this system. Thus, the capability of HSCs may not be studied accurately by this intravenous transplantation method. In our attempt to reveal actual SRC potential, ie, self-renewal and multilineage differentiation in recipient bone marrow, we introduced cells into mouse marrow directly (intrabone marrow [iBM]) to minimize the effect of factors that may interfere with the homing of HSCs and compared the results obtained by intravenous and iBM methods. When cord blood CD34+CD38− cells were transplanted in NOD/SCID mice by iBM, a 15-fold higher frequency of SRC, 1 in 44 CD34+CD38− cells, was achieved compared with 1 in 660 by the intravenous method. Furthermore, the iBM transplant showed high levels of engraftment in the secondary transplantation. Pretreatment of CD34+ cells with antibodies that block either very late antigen 4 (VLA-4) or VLA-5 reduced engraftment partially, whereas blockage of both molecules resulted in complete inhibition of engraftment, which suggests that VLA-4 and VLA-5 are involved in different processes in engraftment or have complementary roles. Our results indicate that the iBM injection strategy is a more sensitive and direct way to measure the capability of human SRCs and is useful to investigate the interaction of HSCs and marrow environment in vivo.
Hematopoietic capacity of connexin43 wild-type and knock-out fetal liver cells not different on wild-type stroma
Authors: Rosendaal Martin , Jopling Chris 
Published: April 2003

AbstractIn 1995 and 1997 we proposed that gap junctions between stromal and hematopoietic cells formed by connexin43 (Cx43) determine hematopoiesis. If this were the case, are the critical gap junctions in this regard those between hematopoietic and stromal cells, or those between stromal cells alone? To test the first possibility, we compared hematopoietic repopulating capacity between fetal liver hematopoietic cells expressing the different mouse Cx43 genotypes, wild type (WT), hemizygous, or knock-out (KO) on WT host mice stroma. We deleted host glucose phosphate isomerase 1a (Gpi-1a) stems and then raced identifiable Cx43 WT host fetal liver against congenic donor Cx43 WT, hemizygous, or KO cells in sets, comparing their capacity to form 5 end cells. Hematopoietic capacity did not differ between the Cx43 WT and KO genotypes. The role of Cx43 gap junctions in hematopoiesis remains uncertain.
Transformation of follicular lymphoma to diffuse large cell lymphoma is associated with a heterogeneous set of DNA copy number and gene expression alterations
Authors: Martinez-Climent Jose A. , Alizadeh Ash A. , Segraves Richard , Blesa David , Rubio-Moscardo Fanny , Albertson Donna G. , Garcia-Conde Javier , Dyer Martin J. S. , Levy Ronald , Pinkel Daniel , Lossos Izidore S. 
Published: April 2003

AbstractGenomic aberrations in a series of paired biopsy samples from patients who presented initially with follicle center lymphoma (FCL) and subsequently transformed to diffuse large B-cell lymphoma (DLBCL) were measured by array comparative genomic hybridization (CGH). The consequences of these aberrations on gene expression were determined by comparison with expression analysis on these specimens using cDNA microarrays. A heterogeneous pattern of acquired genomic abnormalities was observed upon transformation, some of which were recurrent in small subsets of patients. Some of the genomic aberration acquired upon transformation, such as gain/amplification of 1q21-q24, 2p16 (REL/BCL11A gene loci), 3q27-q29 (including theBCL6 locus), 7q11.2-q22.1, 12pter-q12, 18q21 (including theBCL2 locus) and Xq, and deletion of 6q22-q24, 13q14-q21 and 17p13 (P53 locus) have been previously implicated in the FCL/DLBCL pathogenesis. In addition, novel genomic imbalances not previously reported in association with FCL transformation, such as overrepresentation of 4p12-pter, 5p12-p15, 6p12.3-p21, 9p23, 9q13-q31, 16q, 17q21, and loss of 1p36.3, 4q21-q23, 5q21-q23, 9q31-qter, 11q24-q25, and 15q23, were identified. We observed a differential expression profile of many genes within regions of gain and deletion upon transformation, including novel target genes associated with FCL transformation. However, other genes did not show deregulated expression despite their location within these areas. In summary, the combination of array CGH and expression analysis provides a more comprehensive picture of the transformation of FCL to DLBCL. This process is associated with the acquisition of a variable spectrum of genomic imbalances affecting recurrent chromosomal areas that harbor overexpressed or underexpressed genes targeted upon transformation.
Albumin activates the AKT signaling pathway and protects B-chronic lymphocytic leukemia cells from chlorambucil- and radiation-induced apoptosis
Authors: Jones Dylan T. , Ganeshaguru Kanagasabai , Anderson Robert J. , Jackson Trevor R. , Bruckdorfer K. Richard , Low Sylvia Y. , Palmqvist Lars , Prentice H. Grant , Hoffbrand A. Victor , Mehta Atul B. , Wickremasinghe R. Gitendra 
Published: April 2003

AbstractActivation of the phosphatidylinositol 3- kinase/AKT pathway antagonizes apoptosis in diverse cellular systems. We previously showed that human plasma activated AKT and potently blocked the ability of chlorambucil or gamma radiation to induce apoptosis of B-chronic lymphocytic leukemia (CLL) cells. Here we report experiments that identify albumin as the major component of plasma that blocks CLL cell killing by chlorambucil or radiation. Intact plasma depleted of albumin by chromatography on Cibacron blue–Sepharose or plasma from a subject with analbuminemia failed either to activate AKT or to protect CLL cells from chlorambucil-induced apoptosis. Both functions were restored by re-addition of albumin. The protective action of albumin as well as AKT activation was compromised by the binding of lipids. Fluorescence-activated cell sorter (FACScan) analysis demonstrated the uptake of fluoresceinated albumin by CLL cells. Accumulation of albumin in intracellular vesicles was also shown by confocal microscopy. Indirect inhibition of AKT activation by the phosphatidylinositol 3-kinase inhibitor LY294002 reversed the blockade of chlorambucil-induced killing by plasma albumin. The data suggest that activation of AKT consequent to binding of albumin by CLL cells blocks chlorambucil- and radiation-induced apoptosis. Strategies designed to block albumin-induced antiapoptotic signaling may, therefore, be of value in enhancing cytotoxic drug action on CLL cells.