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Erythroid Maturation (erythroid + maturation)
Selected AbstractsThe soluble transferrin receptor in dysplastic erythropoiesis in myelodysplastic syndromeEUROPEAN JOURNAL OF HAEMATOLOGY, Issue 1 2007Georgia Metzgeroth Abstract Objectives:,In individuals without iron deficiency, the soluble transferrin receptor (sTfR) directly reflects the erythropoietic activity. This study investigated sTfR concentrations in ineffective, dysplastic erythropoiesis in myelodysplastic syndrome (MDS). Methods:,To exclude influences of other myeloid cells on sTfR, only patients with refractory anemia (RA), refractory anemia with ringed sideroblasts (RARS) and 5q, syndrome were included. sTfR was measured nephelometrically (normal range 0.81,1.75 mg/L). Results:,Thirty-four untreated MDS patients (RA = 14, RARS = 10, 5q, syndrome = 10) were enrolled and analysed. The mean sTfR value of all MDS patients (1.30 ± 0.8 mg/L, range 0.2,3.8) did not differ from our control group. In 5q, syndrome, the mean sTfR concentration (0.80 ± 0.5 mg/L) was significantly lower than in RA (1.32 ± 0.4 mg/L, P = 0.02) and RARS (1.75 ± 1.1 mg/L, P = 0.03). Subdividing MDS according to their amount of erythroid mass in bone marrow a significant difference of sTfR between patients with decreased (0.70 ± 0.4 mg/L), normal (1.32 ± 0.4 mg/L) and increased (2.06 ± 0.9 mg/L) erythropoiesis was observed. MDS patients with sTfR values below the reference range of 0.81 mg/L required transfusions in 90% of cases and showed higher erythropoietin levels compared to MDS patients with sTfR levels ,0.81 mg/L (P = 0.01). There was a good agreement between sTfR and the amount of polychromatic erythroblasts observed (r = 0.68, P < 0.001). Conclusion:,In conclusion, the serum concentration of sTfR reflects erythropoietic activity in MDS, but it is in particular determined by the degree of erythroid maturation and the severity of ineffective erythropoiesis. Low sTfR values in MDS are associated with a reduced, poorly differentiated erythropoiesis and requirement of blood transfusions. [source] Pivotal role of Notch signaling in regulation of erythroid maturation and proliferationEUROPEAN JOURNAL OF HAEMATOLOGY, Issue 4 2006Yoshimichi Tachikawa Abstract:, Notch signaling plays an important role in cell fate decisions in developmental systems. To clarify its role in committed hematopoietic progenitor cells, we investigated the effects of Notch signaling in erythroid colony forming cells (ECFCs) generated from peripheral blood. ECFCs express Notch receptors, Notch1 and Notch2, and Notch ligands Delta1, Delta4, and Jagged1. When we assayed the effects of Notch ligands on erythroid maturation by flow cytometry, we found that immobilized Delta1 and immobilized Delta4 in particular inhibited maturation, whereas Jagged1 had no effect. In addition, Delta4 inhibited proliferation without reducing cell viability. Increases in expression levels of the Notch target gene hairy enhancer of split (HES) -1 were evident by real-time PCR after stimulation with immobilized Delta4. The effect of soluble Delta4 on expression of HES-1 was less pronounced than that seen with the immobilized form, indicating that all surface-bound ligands are important for effective signal transduction. When ECFCs were cultured in the presence of soluble Delta4 at a low cell concentration, erythroid maturation was slightly inhibited, but at a high concentration, maturation was promoted via competition of soluble Delta4 with endogenous ligands. These results indicate a pivotal role of Notch signaling in regulating erythroid maturation and proliferation, and further suggest that cell,cell interactions modulate growth of erythroid progenitor cells via Notch system. [source] Expression of signal transduction proteins during the differentiation of primary human erythroblastsJOURNAL OF CELLULAR PHYSIOLOGY, Issue 3 2005Viviana di Giacomo The high number (>108,10) of primary human pro-erythroblasts (CD36high/CD235alow) obtainable in HEMA culture (Migliaccio et al., 2002) is exploited here to analyse the expression of proteins implicated in erythropoietin (EPO)-signalling (STATs, PI-3K, and PLCs) during the process of erythroid maturation. Human pro-erythroblasts progressed in 4 days of culture with EPO into basophilic- (CD36high/CD235amedium, 24 h), polychromatic-(CD36high/CD235ahigh, 48 h), and, finally, orthochromatic-(CD36low/CD235ahigh, 72,96 h) erythroblasts. During this maturation, STAT-1 was expressed up to the orthochromatic stage, expression of STAT-5, as well as of its target proteins BclxL and IRF1, remained constant up to 48 h (polychromatic-erythroblasts) but decreased by 96 h (orthochromatic-erythroblasts), while that of STAT-3 decreased constantly from 24 h on and became undetectable by 96 h. Expression of PI-3K rapidly decreased with differentiation since only 50% of original protein levels were detected by 48 h. On the other hand, among the members of PLC families investigated, PLC ,4 was not expressed, PLC ,2, ,1, and ,2 were expressed at constant levels throughout the maturation process, while expression of PLC ,3 and of PLC ,1 decreased, as PI-3K, by 24 h and that of PLC ,1 was induced by 6 h and became undetectable by 24 h. In conclusion, these data depict the dynamic signalling scenario associated with the maturation of erythroid cells and provide the first indication that members of PLC families (PLC ,1, ,3, and ,1) might e involved in the control of erythroid differentiation in humans. © 2004 Wiley-Liss, Inc. [source] Expression analyses and transcriptional regulation of mouse nucleolar spindle-associated protein gene in erythroid cells: essential role of NF-YBRITISH JOURNAL OF HAEMATOLOGY, Issue 4 2006Tohru Fujiwara Summary Nucleolar spindle-associated protein (NuSAP), a recently characterised microtubule-associated protein, appears to participate in cell cycle regulation. It has been demonstrated that NuSAP is expressed preferentially in the erythroid lineage in haematopoietic cells. To characterise its role in erythropoiesis, we examined the expression profile of the NuSAP gene. In fractionated murine erythroblasts, NuSAP mRNA was remarkably more abundant in the subset corresponding to immature erythroblasts (TER119+CD71high) than mature erythroblasts (TER119+CD71low), and it was significantly increased in TER119+ cells from in vivo phlebotomised mice compared with control mice. Furthermore, during erythroid maturation of mouse erythroleukaemia (MEL) cells by dimethylsulfoxide, NuSAP mRNA was increased at 24,72 h. These results suggested that the NuSAP gene might contribute to the expansion of immature erythroblast pool. The regulatory mechanism of NuSAP gene was investigated using MEL cells. Sequence analysis revealed that NuSAP promoter has four CCAAT boxes, an Sp1 element, a GATA-like element, a CACCC element, a Myb element and lacks a TATA box. Promoter analyses demonstrated that duplicated CCAAT boxes located at ,81/,85 and ,30/,34 were essential for promoter activity. Furthermore, the promoter was trans -activated by NF-YA through these elements. These results suggest that NuSAP might play an important role in erythroid proliferation under the control of NF-Y. [source] Clonogenicity, gene expression and phenotype during neutrophil versus erythroid differentiation of cytokine-stimulated CD34+ human marrow cells in vitroBRITISH JOURNAL OF HAEMATOLOGY, Issue 4 2004Louise Edvardsson Summary With the objective to correlate clonogenicity, gene expression and phenotype during differentiation, human bone marrow CD34+ cells were cultured in vitro to stimulate erythroid or neutrophil development, and sorted into five subpopulations according to their surface expression of CD15/CD33 and blood group antigen A/CD117 respectively. Sorted cells were cultured in methylcellulose and analysed by real-time reverse transcription polymerase chain reaction for expression of neutrophil and erythroid marker genes. Surface expression of CD15 coincided with restriction to neutrophil/monocyte differentiation and A antigen with restriction to erythroid differentiation. GATA-2 mRNA was down-regulated during both neutrophil and erythroid maturation, whereas GATA-1, SCL, ABO, erythropoietin receptor, Kell, glycophorin A, , -globin and , -haemoglobin stabilizing protein were up-regulated during erythroid differentiation and silenced during neutrophil differentiation. CCAAT/enhancer-binding protein (C/EBP)- ,, PU.1, granulocyte colony-stimulating factor receptor, PR3, C/EBP- , and lactoferrin were sequentially expressed during neutrophil differentiation but rapidly down-regulated during the early erythroid stages. Nuclear factor erythroid-derived 2 (NF-E2) and glycophorin C were expressed both during neutrophil and erythroid differentiation. Our data support the notion of early expression of several lineage-associated genes prior to actual lineage commitment, defined by surface expression of CD15 and A antigen as markers for definitive neutrophil/monocyte and erythroid differentiation respectively. Previous findings, primarily from cell lines and mouse models, have been extended to adult human haematopoiesis. [source] | ||||||||||