SEARCH · Search PubMed

Results for “Erythroid Cells”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 181 records · Page 10Linked to original sources

PubMed1998

Activation of the human delta-globin gene promoter in primary adult erythroid cells.

Restoration of the CCAAT box or insertion of an erythroid Krüppel-like factor (EKLF) binding site in the delta promoter activates its expression in several erythroid cell lines. We extended these studies using a novel primary human adult erythroid cell (hAEC) system to investigate these effects at the late erythroblast stage. Restoration of the CCAAT box at -70 bp, or insertion of an EKLF binding site at -85 bp or -95 bp in the promoter significantly increased delta globin gene expression in hAEC. Our results demonstrate that the altered CCAAT box (CCAAC) and the lack of an EKLF binding site in delta-globin contribute to its low level of expression in the hAEC model as well.

Adult↗

PubMed2006

Definitive-like erythroid cells derived from human embryonic stem cells coexpress high levels of embryonic and fetal globins with little or no adult globin.

Human embryonic stem cells are a promising tool to study events associated with the earliest ontogenetic stages of hematopoiesis. We describe the generation of erythroid cells from hES (H1) by subsequent processing of cells present at early and late stages of embryoid body (EB) differentiation. Kinetics of hematopoietic marker emergence suggest that CD45+ hematopoiesis peaks at late D14EB differentiation stages, although low-level CD45- erythroid differentiation can be seen before that stage. By morphologic criteria, hES-derived erythroid cells were of definitive type, but these cells both at mRNA and protein levels coexpressed high levels of embryonic (epsilon) and fetal (gamma) globins, with little or no adult globin (beta). This globin expression pattern was not altered by the presence or absence of fetal bovine serum, vascular endothelial growth factor, Flt3-L, or coculture with OP-9 during erythroid differentiation and was not culture time dependent. The coexpression of both embryonic and fetal globins by definitive-type erythroid cells does not faithfully mimic either yolk sac embryonic or their fetal liver counterparts. Nevertheless, the high frequency of erythroid cells coexpressing embryonic and fetal globin generated from embryonic stem cells can serve as an invaluable tool to further explore molecular mechanisms.

Cell Differentiation↗

PubMed1985

Transformation of erythroid cells by Rous sarcoma virus (RSV).

RSV transforms several nonhematopoietic cell types and as reported here also has the capacity to transform hematopoietic cells of the erythroid lineage. In vitro, the three RSV isolates tested induced erythroblast-like colonies in infected bone marrow cells that were distinguishable by size and cell arrangement from those induced by avian erythroblastosis virus (AEV). Also in contrast to AEV-transformed erythroblast cultures, isolated cell colonies induced by RSV required complex growth conditions in liquid medium similar to the in vitro conditions necessary for erythroblasts transformed by the acute leukemia virus E26. Temperature-shift experiments using temperature-sensitive (ts) NY68 RSV revealed that when grown at the nonpermissive temperature (42 degrees), mutant-infected cells became benzidine positive and partially differentiated into erythrocytes. Wild-type (wt) RSV-transformed cells did not undergo similar changes. However, both wt RSV-, and to a greater extent, ts RSV-transformed cultures at the permissive temperature (37 degrees) did contain populations of spontaneously differentiating erythroid cells signifying that the transforming activity of the virus did not fully arrest erythroid maturation. In addition, the RSV-transformed cells did express tyrosine kinase activity. When injected intravenously into birds, RSV induced an erythroblastosis-like disease similar to AEV but also caused fibrosarcomas and leg paralysis. These results show that RSV can alter the pattern of erythroid differentiation in a manner similar to, but distinct from, AEV and indicate that the tyrosine-specific pp60src kinase is involved in erythroid cell transformation. Since the src and erb B proteins share a significant amino acid homology, these data suggest that both may also share a common functional homology.

Alpharetrovirus↗

PubMed1997

Production, metabolism and effect of platelet-activating factor on the growth of the human K562 erythroid cell line.

The human immature K562 erythroid cell line was studied for its capacity to produce and to metabolize the phospholipid molecule platelet-activating factor (PAF). K562 cells produced PAF under calcium ionophore stimulation. Lyso PAF and acetyl-CoA (the acetate donor molecule for the acetylation of lyso PAF into PAF) had no effect on the amounts of PAF produced by ionophore-stimulated cells. The metabolism of PAF and lyso PAF by K562 cells was compared to that of freshly-isolated human bone marrow erythroblasts and blood erythrocytes. K562 cells rapidly metabolized [3H]PAF and [3H]lyso PAF with 1-alkyl analogue of phosphatidylcholine as the major metabolic product. In contrast, blood erythrocytes did not. PAF acetylhydrolase activity levels in K562 cells and bone marrow erythroblasts were similar and higher than in blood erythrocytes. PAF (1-100 nM) stimulated [3H]thymidine incorporation in K562 cells grown in low serum concentration, a non-metabolizable PAF agonist being more potent than PAF to stimulate thymidine incorporation. PAF receptor mRNA was detected in K562 cells by polymerase chain reaction on reverse transcripts. The present study demonstrates that K562 cells produce and metabolize PAF and underlines the putative role of erythroid precursors in the modulation of bone marrow PAF concentrations. The effect of PAF on the growth of K562 cells might be mediated through PAF receptors suggesting a potential role of PAF on the proliferation and functions of human erythroid marrow precursors.

1-Alkyl-2-acetylglycerophosphocholine Esterase↗

PubMed2004

Jun N-terminal kinase promotes proliferation of immature erythroid cells and erythropoietin-dependent cell lines.

Erythropoietin (EPO) is the hormone necessary for development of erythrocytes from immature erythroid cells. EPO activates Jun N-terminal kinase (JNK), a member of the mitogen-activated protein kinase (MAPK) family in the EPO-dependent murine erythroid HCD57 cells. Therefore, we tested if JNK activity supported proliferation and/or survival of these cells. Treatment with the JNK inhibitor SP600125 inhibited JNK activity and EPO-dependent proliferation of HCD57 cells and the human EPO-dependent cell lines TF-1 and UT7-EPO. SP600125 also increased the fraction of cells in G2/M. Introduction of a dominant-negative form of JNK1 inhibited EPO-dependent proliferation in HCD57 cells but did not increase the fraction of cells in G2/M. Constitutive JNK activity was observed in primary murine erythroid progenitors. Treatment of primary mouse bone marrow cells with the SP600125 inhibitor reduced the number of erythroid burst-forming units (BFU-e's) but not the more differentiated erythroid colony-forming units (CFU-e's), and SP600125 protected the BFU-e's from apoptosis induced by cytosine arabinoside, demonstrating that the SP600125 inhibited proliferation of the BFU-e's. Therefore, JNK activity appears to be an important regulator of proliferation in immature, primary erythroid cells and 3 erythroid cell lines but may not be required for the survival or proliferation of CFU-e's or proerythroblasts.

Animals↗

PubMed1985

Determination of the hemoglobin F program in human progenitor-derived erythroid cells.

The absolute adult and fetal hemoglobin (HbF) contents of the erythroid cells derived from the differentiation of normal human and simian erythroid progenitors and of the peripheral blood erythroid burst-forming units (BFU-E) of patients with nondeletion hemoglobinopathies have been measured with a sensitive radioligand immunoassay. The HbF content varied between 0.13 and 2.96 pg/cell, representing between 0.7% and 19.6% of the total hemoglobin with a mean value of 7.0%. The absolute content of HbF was indistinguishable in the well-hemoglobinized progeny of marrow erythroid colony-forming units, marrow or blood BFU-E, or of mixed colony-forming units. The term HbF program refers to this inherent capacity to produce fetal hemoglobin (HbF) in the erythroid cells derived from these progenitors in vitro. The HbF content of marrow erythroblasts as determined by the same radioligand immunoassay was similar to that found in the peripheral blood, suggesting that the switch off of gamma-chain production occurs after the erythroid colony-forming unit stage of maturation. Increasing concentrations of a crude erythropoietin-containing preparation induced higher numbers of erythroid colonies, which were larger in size, but the HbF program was unaffected. In contrast to the hemoglobin accumulation in human progenitor-derived colonies, simian progenitor-derived colonies produced considerably more HbF, and the amount of HbF was strongly influenced by progenitor maturity. Assays of the HbF content of erythroblasts derived from culture of the peripheral blood BFU-E of patients with nondeletion hemoglobinopathies and their parents showed that the HbF program in the progenitors of such patients is highly variable. Some produce only a slight excess of HbF in progenitor-derived erythroblasts, whereas others have extraordinarily high HbF programs. The molecular basis of this variability is presently unknown.

Animals↗

PubMed1993

Measurement of total and fetal hemoglobin in cultured human erythroid cells by a novel micromethod.

The present paper reports on the application of a simple micromethod for quantitation of total and fetal hemoglobin in small volumes of diluted erythroid cell hemolysates. A modified alkaline denaturation procedure was used to denature and precipitate non-fetal hemoglobins and the tetramethylbenzidine procedure was used for quantitation of the soluble hemoglobin. Using a combination of these procedures, total hemoglobin concentrations as low as 0.2 mg% (2 micrograms/ml) and a fetal hemoglobin proportion of 0.5% could be reliably determined. We have utilized this procedure to study two aspects of hemoglobin production in human erythroid cells grown in culture; the proportion of fetal hemoglobin of cells in culture as compared to that in the peripheral blood of the donors, and the kinetics of hemoglobin production during maturation of these cultured cells. The results show that the cultured erythroid cells have a hemoglobin phenotype similar to the individual from whom they are derived and that erythroid differentiation may be studied in vitro in these cultured cells by measurement of these and other parameters.

Anemia, Sickle Cell↗

PubMed2001

Enrichment and detection of fetal erythroid cells from maternal peripheral blood using liquid culture.

Isolating fetal cells from maternal blood for prenatal genetic analysis is the least invasive method currently being investigated. In order to enrich these fetal erythroid cells we employed a two-phase liquid culture system that supports the growth and differentiation of erythroid progenitor cells. Mononuclear cells were separated from ten maternal blood samples at 8-14(+3) weeks of gestation and cultured in the first phase. After 4-5 days, the non-adherent cells were harvested and recultured with erythropoietin for another 3-4 days. The mean number of total erythroid cells reached approximately 0.77x10(6)/ml with an average purity of 90.5%. Hb F stain disclosed fetal erythroid cells averaging approximately 5.7%, therefore the mean number of fetal erythroid cells isolated was 0.49x10(5)/ml. Female karyotypes were only observed while counting 5-66 metaphases. However, male DNA (SRY or DYZ1) was detected by PCR in 7/10 cases; in four of these cases and in one SRY-negative pregnancy the 46,XY karyotype was found by amniocentesis performed during the second trimester. This liquid culture system provided an enriched source of fetal cells without the need for more complicated separation or sorting procedures.

Blood Cells↗

PubMed1986

Induction by hemin of proliferation and of differentiation of progenitor erythroid cells responsible for erythropoietin.

Erythroid progenitor cells were obtained from rat fetal liver by immunolysis of the whole erythroid population with an antiserum directed against adult rat erythrocytes, followed by separation on a density gradient. Immediately after their isolation, these cells contained only minute amounts of globin mRNAs and their heme synthesis was negligible. In the absence of erythropoietin (Epo), they did not proliferate or differentiate. In the presence of Epo, they proliferated, synthetized heme and globins actively, accumulated large amounts of globin mRNAs, and developed hemoglobinized colonies in methylcellulose. Hemin, in concentrations of 5-100 microM, induced, in the absence of Epo, the proliferation and differentiation of these cells (e.g., accumulation of globin mRNAs, synthesis of heme and globins, and increased density of membrane antigens characteristic of the erythrocyte). Nevertheless, Epo and hemin actions were not superimposable: in methylcellulose, Epo induced the appearance of large (greater than or equal to 32 cells) hemoglobinized colonies in 48 h, whereas hemin induced smaller and fewer colonies in only 24 h. Succinylacetone (SA, inhibitor of heme synthesis) mostly prevented the effects of Epo on cell proliferation and differentiation; SA inhibition was relieved by hemin. Thus, hemin seems to intervene in erythroid differentiation as a factor of both proliferation and maturation.

Animals↗

PubMed1964

ALTERATIONS IN POLYRIBOSOMES DURING ERYTHROID CELL MATURATION.

This communication presents a morphological study of the changes in ribosome content and organization which occur during the maturation of erythroid cells of the phenylhydrazine-treated rabbit. Electron micrographs of thin sectioned nucleated and non-nucleated erythroid cells have been subjected to a quantitative analysis of the distribution of ribosomes as polyribosomes of various sizes and as single ribosomes. The ribosomes of nucleated erythroid cells of marrow are virtually all arranged in the polyribosome configuration consisting of clusters of 2 to 6 individual ribosomes. These cells are the most active in the erythroid series in protein biosynthesis. During maturation to the non-nucleated reticulocyte stage, found in the circulating blood, there is a decrease in protein synthesizing capacity, a fall in total ribosome content, and, more significantly, a decrease in the number and size of polyribosomes. Maturation to the ribosome-free erythrocyte, either under in vitro or in vivo conditions, entails a further decrease in protein synthesis which correlates with a progressive disaggregation of the biosynthetically active polyribosomes into smaller clusters and inactive single ribosomes. Possible models which may account for the stability of the polyribosome and for the mechanism of polyribosome dissociation are discussed.

Animals↗

PubMedDate not supplied

[Gene expression in normal and virally transformed erythroid cells and the effect of stress factors].

The globin gene expression in normal and Rauscher virus-transformed murine erythroid cells and the effect of heatshock and cycloheximide (CHI) were investigated. The hybridization analysis of RNA transcripts synthesized using erythroid cell chromatin as a template with globin cDNA demonstrated the disturbance of globin gene transcription in transformed erythroblasts. Using the Northern hybridization analysis of poly(A) +RNA with pCR1 beta MG9 as a probe, the presence of a rather broad RNA set (from approximately 1500 to 450 nucleotides) in these cells was discovered, while hemoglobin was not synthesized. This indicated that the processing of globin mRNA was probably also disturbed. As a result of heatshock, the RNA set approached that in normal erythroid cells (500-650 nucleotides), and the proteins corresponding to globins were synthesized. The stable appearance of low molecular weight proteins and the irregular synthesis of HSP-90 and HSP-70 in response to heat shock were the characteristic features of transformed erythroblasts. After CHI treatment, the content of globin sequences in RNA of transformed erythroblasts increased and beta-globin protein chains appeared.

Animals↗

PubMed1989

The state of DNA methylation of human epsilon-globin gene in erythroid and non-erythroid cells.

The extent of DNA methylation within the embryonic human epsilon-globin gene domain was studied in erythroid and non-erythroid cell lines. The results obtained show that the human epsilon-globin gene is totally methylated at all sites tested in tissues where it is not expressed, i.e. blood leucocytes. In the erythroid cell lines, K562 and PUTKO, both forced to embryonic differentiation by induction with haemin, the level of methylation is reduced compared with that observed in blood leucocytes. In the nonerythroid cell lines HeLa and Rajii, where the human epsilon-globin gene is not expressed, the overall level of methylation in all sites tested is lower compared with that in erythroid cell lines.

Cell Line↗

PubMed1984

Erythropoietin stimulates 45Ca2+ uptake in Friend virus-infected erythroid cells.

It has been shown previously in this laboratory that in vitro infection of mouse bone marrow cells with the anemia strain of Friend leukemia virus leads to growth of large bursts of erythroid cells which are arrested in development prior to hemoglobin synthesis but can respond to erythropoietin (EP) to complete the late stage of erythroblast differentiation. In this study, the effect of EP on the metabolism of 45Ca2+ in these cells was examined. At 4 degrees C, an increased rate of 45Ca2+ uptake and efflux as well as an increase in the steady state level of 45Ca2+ in treated cells was observed. Exchange of 45Ca2+ from preloaded cells at 4 degrees C indicated that treatment with EP increased the size of a rapidly exchanging pool of 45Ca2+ from 5 to 12% of total 45Ca2+ in the cell. The effect of treatment with EP can be seen as increased exchange of extracellular 45Ca2+ with cellular Ca2+; however, an effect of EP on the net level of Ca2+ in these cells cannot be excluded. This investigation demonstrates one of the earliest effects of EP on erythroid cells and suggests that alterations in Ca2+ metabolism may contribute to the progression of erythroid cells to their final development.

Animals↗

PubMed1998

Transport mechanisms for iron and other transition metals in rat and rabbit erythroid cells.

1. Earlier studies have shown that Fe2+ transport into erythroid cells is inhibited by several transition metals (Mn2+, Zn2+, Co2+, Ni2+) and that Fe2+ transport can occur by two saturable mechanisms, one of high affinity and the other of low affinity. Also, the transport of Zn2+ and Cd2+ into erythroid cells is stimulated by NaHCO3 and NaSCN. The aim of the present investigation was to determine whether all of these transition metals can be transported by the processes described for Fe2+, Zn2+ and Cd2+ and to determine the properties of the transport processes. 2. Rabbit reticulocytes and mature erythrocytes and reticulocytes from homozygous and heterozygous Belgrade rats were incubated with radiolabelled samples of the metals under conditions known to be optimal for high- and low-affinity Fe2+ transport and for the processes mediated by NaHCO3 and NaSCN. 3. All of the metals were transported by the high- and low-affinity Fe2+ transport processes and could compete with each other for transport. The Km and Vmax values and the effects of incubation temperature and metabolic inhibitors were similar for all the metals. NaHCO3 and NaSCN increased the uptake of Zn2+ and Cd2+ but not the other metals. 4. The uptake of all of the metals by the high-affinity process was much lower in reticulocytes from homozygous Belgrade rats than in those from heterozygous animals, but there was no difference with respect to low-affinity transport. 5. It is concluded that the high- and low-affinity 'iron' transport mechanisms can also transport several other transition metals and should therefore be considered as general transition metal carriers.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗

PubMed1988

Biosynthesis of heme in immature erythroid cells. The regulatory step for heme formation in the human erythron.

Heme formation in reticulocytes from rabbits and rodents is subject to end product negative feedback regulation: intracellular "free" heme has been shown to control acquisition of transferrin iron for heme synthesis. To identify the site of control of heme biosynthesis in the human erythron, immature erythroid cells were obtained from peripheral blood and aspirated bone marrow. After incubation with human 59Fe transferrin, 2-[14C]glycine, or 4-[14C]delta-aminolevulinate, isotopic incorporation into extracted heme was determined. Addition of cycloheximide to increase endogenous free heme, reduced incorporation of labeled glycine and iron but not delta-aminolevulinate into cell heme. Incorporation of glycine and iron was also sensitive to inhibition by exogenous hematin (Ki, 30 and 45 microM, respectively) i.e. at concentrations in the range which affect cell-free protein synthesis in reticulocyte lysates. Hematin treatment rapidly diminished incorporation of intracellular 59Fe into heme by human erythroid cells but assimilation of 4-[14C]delta-aminolevulinate into heme was insensitive to inhibition by hematin (Ki greater than 100 microM). In human reticulocytes (unlike those from rabbits), addition of ferric salicylaldehyde isonicotinoylhydrazone, to increase the pre-heme iron pool independently of the transferrin cycle, failed to promote heme synthesis or modify feedback inhibition induced by hematin. In human erythroid cells (but not rabbit reticulocytes) pre-incubation with unlabeled delta-aminolevulinate or protoporphyrin IX greatly stimulated utilization of cell 59Fe for heme synthesis and also attenuated end product inhibition. In human erythroid cells heme biosynthesis is thus primarily regulated by feedback inhibition at one or more steps which lead to delta-aminolevulinate formation. Hence in man the regulatory process affects generation of the first committed precursor of porphyrin biosynthesis by delta-aminolevulinate synthetase, whereas in the rabbit separate regulatory mechanisms exist which control the incorporation of iron into protoporphyrin IX.

Adolescent↗

PubMed1978

Changes in the lactate dehydrogenase isoenzyme pattern during differentiation of rabbit bone-marrow erythroid cells.

1. Differentiation and maturation of rabbit bone-marrow erythroid cells was accompanied by a 15-fold decrease in lactate dehydrogenase activity from approx. 0.1pmol of NADH utilized/min per cell in basophilic cells to 0.007 pmol of NADH/min per cell in reticulocytes. 2. In early cells, cell division takes place with a corresponding decrease in cell volume, but the concentration of lactate dehydrogenase remains almost constant. 3. When cell division ceases, qualitative as well as quantitative changes in the lactate dehydrogenase isoenzyme pattern become apparent and reticulocytes were found to contain almost exclusively the H4 isoenzyme, whereas early erythroblasts contained also the M4 and hybrid isoenzymes. 4. Extracts from a lysosome-enriched subcellular fraction of bone-marrow erythroid cells specifically degraded the M4 isoenzyme in vitro, but the H4 form was stable. It is suggested that lysosomal enzymes are involved in bringing about the observed changes in lactate dehydrogenase isoenzyme patterns in vivo.

Animals↗

PubMed1983

Transferrin endocytosis and iron uptake during erythroid cell development.

Electron microscope autoradiography was used to quantitate the uptake of transferrin and transferrin-bound iron by rat erythroid cells at the various stages of development. The capacity of the cells to take up iron closely paralleled their ability to bind transferrin, suggesting that the level of transferrin receptors is the major factor which regulates the rate at which immature erythroid cells can accumulate iron. Maximal transferrin and iron uptake occurred at the basophilic normoblast stage and then decreased progressively during maturation to the reticulocyte. During development, immature rat erythroid cells acquire about twice as much iron from transferrin as is present in the haemoglobin of mature erythrocytes.

Animals↗

PubMed1983

Vimentin filaments are assembled from a soluble precursor in avian erythroid cells.

The synthesis and assembly of vimentin was studied in erythroid cells from 10-d-old chicken embryos. After various periods of [35S]methionine incorporation, cells were lysed in a Triton X-100-containing buffer and separated into a soluble and an insoluble (cytoskeletal) fraction. Analysis of these two fractions by two-dimensional gel electrophoresis shows that vimentin is almost exclusively present in the cytoskeletal fraction and that newly synthesized vimentin is rapidly incorporated into this fraction. However, after a short pulse-labeling period, a prominent labeled protein at the position of vimentin is present in the soluble fraction. By immunoautoradiography and immunoprecipitations with vimentin antibodies, this protein was identified as vimentin. The vimentin in the soluble fraction is not sedimented by high speed centrifugation, suggesting that it does not consist of short filaments. After different pulse-labeling periods, assembly of newly synthesized vimentin in the cytoskeletal fraction increases linearly, while the radioactivity in the soluble vimentin remains constant. During a 2-h pulse-chase period, the vimentin in the soluble fraction is chased into the cytoskeletal fraction, with a half-life of 7 min. These results suggest that in chicken embryo erythroid cells newly synthesized vimentin is rapidly assembled into filaments from a soluble precursor.

Animals↗