FOG1 requires NuRD to promote hematopoiesis and maintain lineage fidelity within the megakaryocytic-erythroid compartment

Abstract Nuclear factors regulate the development of complex tissues by promoting the formation of one cell lineage over another. The cofactor FOG1 interacts with transcription factors GATA1 and GATA2 to control erythroid and megakaryocyte (MK) differentiation. In contrast, FOG1 antagonizes the ability of GATA factors to promote mast cell (MC) development. Normal FOG1 function in late-stage erythroid cells and MK requires interaction with the chromatin remodeling complex NuRD. Here, we report that mice in which the FOG1/NuRD interaction is disrupted (Fogki/ki) produce MK-erythroid progenitors that give rise to significantly fewer and less mature MK and erythroid colonies in vitro while retaining multilineage capacity, capable of generating MCs and other myeloid lineage cells. Gene expression profiling of Fogki/ki MK-erythroid progenitors revealed inappropriate expression of several MC-specific genes. Strikingly, aberrant MC gene expression persisted in mature Fogki/ki MK and erythroid progeny. Using a GATA1-dependent committed erythroid cell line, select MC genes were found to be occupied by NuRD, suggesting a direct mechanism of repression. Together, these observations suggest that a simple heritable silencing mechanism is insufficient to permanently repress MC genes. Instead, the continuous presence of GATA1, FOG1, and NuRD is required to maintain lineage fidelity throughout MK-erythroid ontogeny.

Download Full-text

Dysregulated Expression of miRNAs in Polycythemia Vera Erythroid Progenitors.

Blood ◽

10.1182/blood.v108.11.3613.3613 ◽

2006 ◽

Vol 108 (11) ◽

pp. 3613-3613

Author(s):

Hana Bruchova ◽

Amos S. Gaikwad ◽

Joshua Mendell ◽

Josef T. Prchal

Keyword(s):

Gene Expression ◽

Polycythemia Vera ◽

Jak2 V617f ◽

Prediction Algorithm ◽

Erythroid Cell ◽

Molecular Defect ◽

Erythroid Progenitors ◽

Hematopoietic Stem ◽

Homogeneous Population

Abstract Polycythemia vera (PV), the most common myeloproliferative disorder, arises due to somatic mutation(s) of a single hematopoietic stem cell leading to clonal hematopoiesis. A somatic JAK2 V617F point mutation is found in over 80% of PV patients; however, it is not clear if the JAK2 V617F is the disease initiating mutation, sincethere are PV JAK2 V617F negative patients who have monoclonal hematopoiesis and erythropoietin independent erythropoiesis;in individual PV families, there are PV subjects with and without the JAK2 V617F mutation; andanalysis of clonal PV populations reveals the presence of <50 and >50% mutated JAK2 cells (Nussenzweig’ abstract this mtg), suggesting a mixed population of cells with regard to JAK2 status.In order to search for possible PV contributing molecular defect(s), we studied microRNAs (miRNAs) in a homogeneous population of in vitro expanded erythroid progenitors. MiRNAs are non-coding, small RNAs that regulate gene expression at the posttranscriptional level by direct mRNA cleavage, by translational repression, or by mRNA decay mediated by deadenylation. MiRNAs play an important regulatory role in various biological processes including human hematopoiesis. In vitro expanded erythroid progenitors were obtained from peripheral blood mononuclear cells of 5 PV patients (JAK2 V617F heterozygotes) and from 2 healthy donor controls. The cells were cultured in an erythroid-expansion medium for 21 days resulting in 70–80% homogenous erythroid cell population of identical differentiation stage. Gene expression profiling of miRNAs (Thomson, Nature Methods, 1:1, 2004) was performed using a custom microarray (Combimatrix) with 326 miRNA probes. Data were normalized by the global median method. The miRNAs with expression ratios greater than 1.5 or less than 0.5 were considered to be abnormal. Comparative analyses of controls versus PV samples revealed up-regulated expression of miR-let7c/f, miR-16, miR-451, miR-21, miR-27a, miR-26b and miR-320 and down-regulation of miR-150, miR-339 and miR-346 in PV. In addition, miR-27a, miR-26b and miR-320 were expressed only in PV. The putative targets of these miRNAs were predicted by TargetScan prediction algorithm. Up-regulated miR-let-7, miR-16 and miR-26b may modulate cyclin D2, which has an important role in G1/S transition and can be a target in the JAK2/STAT5 pathway (Walz, JBC, 281:18177, 2006). One of the putative targets of up-regulated miR-27a is EDRF1 (erythroid terminal differentiation related factor1), a positive regulator of erythroid differentiation. The BCL-6 gene is predicted to be the target of miR-339 and miR-346, and its activation blocks cellular differentiation. MiR-16 is known to be down-regulated in CLL, where it targets anti-apoptotic BCL-2; in contrast, we show that miR-16 is up-regulated in PV erythroid cells. We identified differentially expressed miRNAs in PV which target genes involved in the JAK/STAT pathway or genes that are modulated by JAK2 downstream molecules. This study indicates that miRNA dysregulation may play an important role in erythropoietic differentiation and proliferation in PV. Expression analyses of these miRNAs in a larger set of PV samples, using quantitative Real-Time-PCR, are in progress. Further, earlier erythroid and pluripotent hematopoietic progenitors are also being analyzed.

Download Full-text

Growth and Differentiation of Human Stem Cell Factor/Erythropoietin-Dependent Erythroid Progenitor Cells In Vitro

Blood ◽

10.1182/blood.v92.10.3658 ◽

1998 ◽

Vol 92 (10) ◽

pp. 3658-3668 ◽

Cited By ~ 128

Author(s):

Birgit Panzenböck ◽

Petr Bartunek ◽

Markus Y. Mapara ◽

Martin Zenke

Keyword(s):

Stem Cell ◽

Progenitor Cells ◽

Stem Cell Factor ◽

Large Cell ◽

Erythroid Cell ◽

Erythroid Progenitors ◽

Peripheral Blood Stem Cells ◽

Erythroid Progenitor ◽

Cell Numbers

Abstract Stem cell factor (SCF) and erythropoietin (Epo) effectively support erythroid cell development in vivo and in vitro. We have studied here an SCF/Epo-dependent erythroid progenitor cell from cord blood that can be efficiently amplified in liquid culture to large cell numbers in the presence of SCF, Epo, insulin-like growth factor-1 (IGF-1), dexamethasone, and estrogen. Additionally, by changing the culture conditions and by administration of Epo plus insulin, such progenitor cells effectively undergo terminal differentiation in culture and thereby faithfully recapitulate erythroid cell differentiation in vitro. This SCF/Epo-dependent erythroid progenitor is also present in CD34+ peripheral blood stem cells and human bone marrow and can be isolated, amplified, and differentiated in vitro under the same conditions. Thus, highly homogenous populations of SCF/Epo-dependent erythroid progenitors can be obtained in large cell numbers that are most suitable for further biochemical and molecular studies. We demonstrate that such cells express the recently identified adapter protein p62dok that is involved in signaling downstream of the c-kit/SCF receptor. Additionally, cells express the cyclin-dependent kinase (CDK) inhibitors p21cip1 and p27kip1 that are highly induced when cells differentiate. Thus, the in vitro system described allows the study of molecules and signaling pathways involved in proliferation or differentiation of human erythroid cells.

Download Full-text

Dynamic Change in the Stochiometry of ETO2 and SCL Governs the Transition to Terminal Differentiation in Erythroid Progenitors.

Blood ◽

10.1182/blood.v108.11.1169.1169 ◽

2006 ◽

Vol 108 (11) ◽

pp. 1169-1169

Author(s):

Julie A. Lambert ◽

Nicolas Goardon ◽

Patrick Rodriguez ◽

Sabine Herblot ◽

Pierre Thibault ◽

...

Keyword(s):

Gene Expression ◽

Cell Proliferation ◽

Chromatin Immunoprecipitation ◽

Target Genes ◽

Terminal Differentiation ◽

Erythroid Differentiation ◽

Erythroid Cell ◽

Erythroid Progenitors ◽

The Core ◽

Undifferentiated Cells

Abstract As highly proliferative erythroid progenitors commit to terminal differentiation, they also progressively undergo growth arrest. To determine the mechanisms underlying the appropriate timing of erythroid gene expression and those associated with growth cessation, we analyzed the dynamical composition of the multiprotein complex nucleated by the bHLH transcription factor SCL, a crucial regulator of erythropoiesis that absolutely requires interaction with other factors to activate transcription. In progenitor cells, the SCL complex marks a subset of erythroid specific genes (alpha-globin, P4.2, glycophorin A) that are transcribed later in differentiating cells, conducting cells toward terminal maturation. To unravel the regulation of transcription by SCL, we used tagging/proteomics approaches in two differentiation-inducible erythroid cell lines, coupled with binding assays to immobilized DNA templates and chromatin immunoprecipitation. Our analyses reveal that the core complex comprised of known proteins (SCL, GATA-1, LMO2, Ldb1 and E2A) and two additional E protein family members, HEB and E2-2, did not change with differentiation. Strikingly, this complex recruits HDAC1-2 in undifferentiated cells which were exchanged with TRRAP, a chromatin remodelling factor, upon differentiation, suggesting an epigenetic regulation of erythroid differentiation mediated by the core SCL complex. Finally, we identified the corepressor ETO2 targeted via this complex through direct interaction with E2A/HEB. In vivo, ETO2 represses the transcription of SCL target genes both in transient assays and in chromatin. During erythroid differentiation, ETO2 remains associated with the SCL complex bound to erythroid promoters. However, the stoichiometry of ETO2 and SCL/HEB changes as SCL and HEB levels increase with erythroid differentiation, both in nuclear extracts and on DNA. To determine the functional consequence of this imbalance in activator to co-repressor ratio, we delivered ETO2 siRNA in primary hematopoietic cells and found an accelerated onset of SCL target genes on induction of erythroid differentiation, and conversely, these genes were decreased following ectopic ETO2 expression. Strikingly, inhibition of ETO2 expression in erythroid progenitors arrests cell proliferation, indicating that ETO2 is required for their expansion. We therefore analyzed gene expression in purified erythroid progenitors and differentiating erythroid cells (E1-E5) and found an inverse correlation between the mRNA levels of ETO2 and cyclin-dependent kinase inhibitors. Moreover, ETO2 siRNA treatment of primary erythroid progenitors results in increased p21 CDKI and Gfi1b expression, as assessed by real-time PCR. Finally, we show by chromatin immunoprecipitation that Gfi-1b, p21 and p27, are direct targets of the SCL- ETO2 complex. We therefore conclude that ETO2 regulates the erythroid lineage fate by repressing SCL marked erythroid genes in undifferentiated cells, and by controlling the expansion of erythroid progenitors. Our study elucidates the dual function of ETO2 in the erythroid lineage and sheds light on epigenetic mechanisms coordinating red blood cell proliferation and differentiation.

Download Full-text

Lenalidomide Up-Regulates SPARC and Inhibits In Vitro Growth of the Malignant Clone in Myelodysplastic Syndrome Patients with 5q Deletion.

Blood ◽

10.1182/blood.v108.11.855.855 ◽

2006 ◽

Vol 108 (11) ◽

pp. 855-855

Author(s):

Andrea Pellagatti ◽

Martin Jädersten ◽

Ann-Mari Forsblom ◽

Helen Cattan ◽

Birger Christensson ◽

...

Keyword(s):

Gene Expression ◽

Myelodysplastic Syndrome ◽

Transforming Growth Factor Beta ◽

Transforming Growth Factor ◽

Expression Profiles ◽

Activin A ◽

Healthy Controls ◽

Erythroid Progenitors ◽

Normal Cells

Abstract The immunomodulatory drug lenalidomide induces cytogenetic remissions in 75% of patients with myelodysplastic syndrome (MDS) and del(5)(q31) through unknown mechanisms. We investigated the in vitro effects of lenalidomide on growth and maturation in differentiating erythroblasts from MDS patients with del(5)(q31) (n=13) and from healthy controls (n=10). Lenalidomide selectively inhibited growth of del(5q) erythroblasts, while not affecting normal cells, including cytogenetically normal cells from MDS del(5q) patients. The inhibitory effect was more pronounced in erythroid than in myeloid cells. In order to gain insight into the mode of action of lenalidomide and to identify the molecular targets of this drug, we have investigated the gene expression profiles of the lenalidomide-treated and untreated intermediate erythroblasts from MDS del(5q) patients (n=9) and from healthy controls (n=8). GeneChip Human Genome U133 Plus 2.0 arrays (Affymetrix), covering over 47,000 transcripts representing 39,000 human genes, were used. Treatment with lenalidomide significantly influenced the pattern of gene expression in del(5q) intermediate erythroblasts, with up-regulation of VSIG4, PPIC, TPBG, and SPARC in all samples, and down-regulation of many genes involved in erythropoiesis, including HBA2, GYPA, and KLF1, in most samples. Up-regulation of SPARC (median 4.4-fold, range 2.4–9.5) is of particular interest since SPARC, a gene with known tumor suppressor functions, is both anti-proliferative and anti-angiogenic, and is located at 5q31–q32, within the commonly deleted region in MDS 5q- syndrome. Activin A was one of the most significant differentially expressed genes between lenalidomide-treated cells of MDS del(5q) patients and healthy controls. Activin A is a member of the transforming growth factor-beta superfamily, with pleiotropic functions including apoptosis of hemopoietic cells. We conclude that lenalidomide specifically inhibits growth of del(5q) erythroid progenitors, while not affecting cytogenetically normal cells. These novel findings suggest that up-regulation of SPARC and Activin A may underlie the potent effects of lenalidomide, in particular growth inhibition and anti-angiogenesis, in MDS with del(5)(q31). The localization of the SPARC gene to the CDR of the 5q- syndrome is intriguing and, in relation to the findings of the present study, we suggest that SPARC may well play a role in the molecular pathogenesis of the 5q- syndrome.

Download Full-text

Mutation Of The Divalent Metal Transporter (Dmt1) Gene Results In Inefficient Induction Of The Erythroid Transcriptional Program Due To Latter Onset Of GATA-1 and Epor Expression

Blood ◽

10.1182/blood.v122.21.2197.2197 ◽

2013 ◽

Vol 122 (21) ◽

pp. 2197-2197

Author(s):

Nikola Curik ◽

Pavel Burda ◽

Tomas Zikmund ◽

Filipp Savvulidi ◽

Monika Horvathova ◽

...

Keyword(s):

Gene Expression ◽

Bone Marrow ◽

Flow Cytometry ◽

Iron Uptake ◽

Stage Iv ◽

Erythroid Progenitors ◽

Ineffective Erythropoiesis ◽

Divalent Metal Transporter ◽

Epor Expression

Abstract Introduction Divalent metal transporter 1 (DMT1; SLC11A2) encodes trans-membrane protein variants that execute either non-heme iron absorption through apical duodenal membrane of enterocytes or transferrin-bound iron uptake through endosomal membrane of erythroid (and other) cells. Since 2005 several DMT1 mutations affecting accurate protein folding and localization were identified in patients with defective iron uptake leading to microcytic anemia, abnormal growth of erythroid progenitors in vitro, and iron overload in the liver. We have previously demonstrated that defective growth of DMT-1-mutatnt BFU-Es in vitro and anemia associated with ineffective erythropoiesis in vivo can be improved with high-dose erythropoietin (EPO) supplementation (Horvathova et al., 2012). Data from Dmt1-mutant mk/mk mice (Gunshin et al., 2005) suggested that the anemic phenotype is a result of ineffective erythropoiesis within bone marrow and spleen. Hypothesis DMT1-mutant erythropoiesis inhibits EPO receptor (EPOR) signaling whose end-point target as well as upstream activator is the key transcription factor GATA-1. This results in defective erythroid development characterized by impaired survival capacity of erythroid progenitors, increased apoptosis of erythroblasts, and dysregulation of erythroid gene expression leading to ineffective erythropoiesis. Materials Bone marrow cells of murine mk/mk mice were sorted using flow cytometry to obtain differentiating erythroid fractions based on antigens Cd71 and Ter119 (Sokolovsky et al., 2001) which were then subjected to gene expression analysis. Results Firstly, four consecutive fractions (proerythroblasts and early basophilic erythroblasts - stage I, late basophilic erythroblasts – stage II, chromathophillic and orthochromathophillic erythroblasts – stage III, and late chromathophillic erythroblasts and reticulocytes – stage IV) were isolated from mk/mk mice and control littermates. Flow cytometry showed enrichment in stages I and II and depletion in stage IV in the mk/mk bone marrow when compared to wild type controls, consistent with our previous data. In the spleen the major cellular enrichment was seen in stage III accompanied by cell depletion in stage IV. Gene expression of GATA-1 was markedly decreased at the onset (in stages I and II) of erythropoiesis while it was increased in terminal stage IV. The expression pattern of the GATA-1 target gene Epor was similar to that of GATA-1 expression, while expression of b-maj globin was significantly reduced indicating developmental delay of the erythroid Dmt1-mutant compartment (compared to wild type). Whereas GATA-1 and Epor expression is low in early erythropoiesis, a compensatory increase in their expression at later stages is not capable to efficiently upregulate b-maj globin. These data together with flow cytometry analysis identify a developmental blockade of erythropoiesis between stages II(III) and IV. To better understand whether Dmt1 levels regulate GATA-1 and Epor expression we used murine erythroleukemia (MEL) cells containing conditional (estrogen-regulated) transgene encoding GATA-1 fused with estrogen receptor ligand-binding domain (GER). MEL cells are cytologically characterized as proerythroblasts and early basophilic erythroblasts, stage I. Firstly, we established that GATA-1 upregulates Epor expression and directly binds to the Epor gene using RT-PCR, Immunoblotting, and chromatin immunoprecipitation (ChIP) in activated GER cells. Using ChIP-sequencing analysis of GATA-1 (and a panel of histone modifications) the GATA-1 enrichment was clearly identified at three distinct Epor regions in murine erythroblasts and differentiating MEL cells. Next, we downregulated Dmt1 using siRNA and observed that GATA-1-mediated upregulation of Epor in activated GER cells became inhibited. In addition, the knockdown of Dmt1 also inhibited steady state levels of GATA-1 in MEL cells by 25%. Conclusions Ineffective erythropoiesis in Dmt1-mutant mice is blocked at stages II (III) and display deregulation of the Epor signaling cascade involving GATA-1 and its targets. Our data thus interconnect iron uptake and the Epor/GATA-1 pathways and suggest their roles during erythroid pathogenesis upon DMT1 mutations. Grants: P305/11/1745, P301/12/P380, P305/12/1033, UNCE 204021, PRVOUK-P24/LF1/3, SVV-2012-264507, GAUK 251135 82210 Disclosures: No relevant conflicts of interest to declare.

Download Full-text

Establishment of long-term monolayer cultures of somatic cells from human fetal testes and expansion of peritubular myoid cells in the presence of androgen

Reproduction ◽

10.1530/rep-09-0532 ◽

2010 ◽

Vol 139 (4) ◽

pp. 749-757 ◽

Cited By ~ 11

Author(s):

Gillian Cowan ◽

Andrew J Childs ◽

Richard A Anderson ◽

Philippa T K Saunders

Keyword(s):

Gene Expression ◽

Cultured Cells ◽

Smooth Muscle Actin ◽

Cell Monolayer ◽

Somatic Cells ◽

Cell Lineage ◽

Culture Conditions ◽

Monolayer Cultures ◽

The Impact

The somatic (Sertoli cell (SC), Leydig cell (LC), and peritubular myoid (PTM) cell) cells play key roles in development of the fetal testis. We established monolayer cultures from second trimester human testes and investigated the pattern of expression of cell-lineage characteristic mRNAs. Expression of some SC-associated genes (SRY, SOX9, WT1, GATA4, and SF1) was detectable up to and including passage 3 (P3), while others (anti-Müllerian hormone; desert hedgehog) present prior to dissociation were not expressed in the cultured cells. Transcripts encoding the androgen receptor were expressed but addition of dihydrotestosterone (DHT) had no impact on expression of mRNAs expressed in SC or LC. Total concentrations of mRNAs encoding smooth muscle actin (ACTA2) and desmin increased from P1 to P3; an increasing proportion of the cells in the cultures were immunopositive for ACTA2 consistent with proliferation/differentiation of PTM cells. In conclusion, somatic cell monolayer cultures were established from human fetal testes; these cultures could form the basis for future studies based on isolation of purified populations of somatic cells and manipulation of gene expression that is difficult to achieve with organ culture systems. Our results suggest that fetal SC do not maintain a fully differentiated phenotype in vitro, yet PTM (ACTA2 positive) cells readily adapt to monolayer culture conditions in the presence of DHT. This culture system provides an opportunity to study the impact of regulatory factors on gene expression in PTM cells, a population thought to play a key role in mediating androgen action within the developing testis.

Download Full-text

Effect of modulators of erythropoiesis on the hemoglobinization of human erythroid cell cultures

Blood ◽

10.1182/blood.v60.2.346.bloodjournal602346 ◽

1982 ◽

Vol 60 (2) ◽

pp. 346-351

Author(s):

BJ Clarke ◽

AM Brickenden ◽

RA Ives ◽

DH Chui

Keyword(s):

Human Peripheral Blood ◽

Spectrophotometric Assay ◽

Conditioned Media ◽

Erythroid Cell ◽

Erythroid Progenitors ◽

Hemoglobin Content ◽

Plasma Clot ◽

Total Hemoglobin ◽

Valuable Adjunct

A rapid spectrophotometric assay capable of detecting the hemoglobin content of 1000 mature erythrocytes has been utilized to quantitate the total hemoglobin synthesized by the progeny of circulating human erythroid progenitors in both the plasma clot and methylcellulose culture systems. The pronounced variation in the effect of different erythropoietin preparations on the hemoglobin content of cultured human peripheral blood bursts, previously described in a subjective manner, has been objectively quantitated. Further experiments demonstrated that both lymphocyte conditioned media and dexamethasone substantially increased the total hemoglobin synthesized by the progeny of cultured erythroid progenitors. The elevated amount of hemoglobin present in erythroid cultures containing either lymphocyte conditioned media and/or dexamethasone was due to both increased colony numbers and colony size. Assay of the total hemoglobin content per erythroid culture is an accurate, sensitive, measure of erythropoiesis in vitro and should be a valuable adjunct to the enumeration of BFU-E-derived erythroid colonies.

Download Full-text

Pharmacological Inhibition of K-Cl Cotransport Alters In Vitro Maturation of Normal and β-Thalassemic Human Erythroid Progenitors.

Blood ◽

10.1182/blood.v106.11.3819.3819 ◽

2005 ◽

Vol 106 (11) ◽

pp. 3819-3819

Author(s):

Lucia De Franceschi ◽

Luisa Ronzoni ◽

Achille Iolascon ◽

Francesca Cimmino ◽

Seth L. Alper ◽

...

Keyword(s):

Gene Expression ◽

Cell Cycle ◽

Cell Growth ◽

Protein Expression ◽

Mrna Level ◽

Cell Volume Regulation ◽

Erythroid Cell ◽

Cell Counts ◽

Normal Controls

Abstract The K-Cl cotransporter family (KCC) plays a crucial role in cell volume regulation, and KCC1 and KCC3 have been reported to participate in cell growth events (Shen MR, PNAS98, 2001; Shen MR JBC278, 2003). Expression of KCC1, KCC3 and KCC4 has been reported in erythroid cells. In β-thalassemic red blood cells (RBCs), K-Cl cotransport activity is abnormally activated and contributes to red cell loss of water and K. This study evaluated the gene expression of two KCC gene products and the effects of the KCC inhibitor [(dihydroindoenyl)oxy]alkanoic acid (DIOA) on in vitro liquid-culture expansion of human normal and β thalassemic (β thal) erythroid precursors from peripheral blood CD34+ cells. Cells from normal subjects and from β thalassemia major patients (cod39cod39) were cultured for 7 days (to the pro-normobast stage) and 14 days (to the eythroblast stage) in the presence or absence of 10 mM DIOA, At each time point the following parameters were evaluated; cells counts; cytospins stained with Wright-Giemsa to assess differential cell counts and morphology, cell cycle stage by fluorescence-activated cell sorting after propidium iodide staining; KCC protein expression by Western-blot analysis with antibody to the shared KCC carboxy-terminus; mRNA by real time-PCR analysis. KCC protein expression increased during erythropoiesis in both normal and β thal cells, and was higher in β thal cells than in normal controls. KCC1 mRNA level was increased only in β thal cells at day 14, whereas KCC3 mRNA level was increased at day 14 in both normal and β thal cells. DIOA significantly reduced the number of both normal and β thal cells, parallelled by increases in the percentage of polychromatophilic normoblasts among normal progenitors and of basophilic normoblasts among b thal progenitors. We further investigated the inhibitory effects of DIOA on cell growth by FACS evaluation of cell cycle distributions and by determination ofCycD, p21, Casp3 and Casp8 gene expression. At day 14 DIOA exposure was associated with: significant reduction in the percentage of β thal cells in S-phase compared to either untreated cells or DIOA-treated normal controls; up-regulation of CycD gene expression in both normal and β thal cells; down-regulation of p21 in β thal cells; up-regulation of casp3 and casp8 in both normal and β thal cells. These data suggest that KCC is involved in the late phase of erythropoiesis mainly in β thal cells, and support a novel role of KCC in erythroid cell growth.

Download Full-text

Stress erythropoiesis in atherogenic mice

Scientific Reports ◽

10.1038/s41598-020-74665-x ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Ángela Sánchez ◽

Marta C. Orizaola ◽

Diego Rodríguez-Muñoz ◽

Ana Aranda ◽

Antonio Castrillo ◽

...

Keyword(s):

Bone Marrow ◽

Apolipoprotein E ◽

Blood Cells ◽

High Fat Diet ◽

Cell Lineage ◽

Erythroid Cell ◽

High Fat ◽

Erythroid Progenitors ◽

Stress Erythropoiesis ◽

Colony Forming Unit

Abstract Bone marrow erythropoiesis is mainly homeostatic and a demand of oxygen in tissues activates stress erythropoiesis in the spleen. Here, we show an increase in the number of circulating erythrocytes in apolipoprotein E−/− mice fed a Western high-fat diet, with similar number of circulating leukocytes and CD41+ events (platelets). Atherogenic conditions increase spleen erythropoiesis with no variations of this cell lineage in the bone marrow. Spleens from atherogenic mice show augmented number of late-stage erythroblasts and biased differentiation of progenitor cells towards the erythroid cell lineage, with an increase of CD71+CD41CD34−CD117+Sca1−Lin− cells (erythroid-primed megakaryocyte-erythroid progenitors), which is consistent with the way in which atherogenesis modifies the expression of pro-erythroid and pro-megakaryocytic genes in megakaryocyte-erythroid progenitors. These data explain the transiently improved response to an acute severe hemolytic anemia insult found in atherogenic mice in comparison to control mice, as well as the higher burst-forming unit-erythroid and colony forming unit-erythroid capacity of splenocytes from atherogenic mice. In conclusion, our work demonstrates that, along with the well stablished enhancement of monocytosis during atherogenesis, stress erythropoiesis in apolipoprotein E−/− mice fed a Western high fat diet results in increased numbers of circulating red blood cells.

Download Full-text

K-Ras is essential for normal fetal liver erythropoiesis

Blood ◽

10.1182/blood-2004-05-2021 ◽

2005 ◽

Vol 105 (9) ◽

pp. 3538-3541 ◽

Cited By ~ 23

Author(s):

Waleed F. Khalaf ◽

Hilary White ◽

Mary Jo Wenning ◽

Attilio Orazi ◽

Reuben Kapur ◽

...

Keyword(s):

Fetal Liver ◽

Erythroid Cell ◽

Wild Type ◽

Erythroid Progenitors ◽

Kit Ligand ◽

Ras Activation ◽

Ras Isoforms ◽

Fetal Erythropoiesis

AbstractIn vitro studies suggest that Ras activation is necessary for erythroid cell development. However, genetic inactivation of the Ras isoforms H-Ras, N-Ras, and K-Ras in mice reportedly did not affect adult or fetal erythropoiesis, though K-Ras-/- embryos were anemic. Given these discrepancies, we performed a more detailed analysis of fetal erythropoiesis in K-Ras-/- embryos. Day-13.5 K-Ras-/- embryos were pale with a marked reduction of mature erythrocytes in their fetal livers. The frequency and number of both early (erythroid burst-forming unit [BFU-E]) and late erythroid progenitors (erythroid colony-forming unit [CFU-E]) were reduced in K-Ras-/- fetal livers compared with wild-type controls and displayed a delay in terminal erythroid cell maturation. Further, K-Ras-/- hematopoietic progenitors had reduced proliferation in response to erythropoietin and Kit ligand compared with control cells. Thus, these studies identify K-Ras as a unique Ras isoform that is essential for regulating fetal erythropoiesis in vivo.

Download Full-text