Survival and proliferative roles of erythropoietin beyond the erythroid lineage

Since the isolation and purification of erythropoietin (EPO) in 1977, the essential role of EPO for mature red blood cell production has been well established. The cloning of theEPOgene and production of recombinant human EPO led to the widespread use of EPO in treating patients with anaemia. However, the biological activity of EPO is not restricted to regulation of erythropoiesis. EPO receptor (EPOR) expression is also found in endothelial, brain, cardiovascular and other tissues, although at levels considerably lower than that of erythroid progenitor cells. This review discusses the survival and proliferative activity of EPO that extends beyond erythroid progenitor cells. Loss of EpoR expression in mouse models provides evidence for the role of endogenous EPO signalling in nonhaematopoietic tissue during development or for tissue maintenance and/or repair. Determining the extent and distribution of receptor expression provides insights into the potential protective activity of EPO in brain, heart and other nonhaematopoietic tissues.

Download Full-text

Role of Erythropoietin Receptor Signaling in Parvovirus B19 Replication in Human Erythroid Progenitor Cells

Journal of Virology ◽

10.1128/jvi.01229-10 ◽

2010 ◽

Vol 84 (23) ◽

pp. 12385-12396 ◽

Cited By ~ 43

Author(s):

Aaron Yun Chen ◽

Wuxiang Guan ◽

Sai Lou ◽

Zhengwen Liu ◽

Steve Kleiboeker ◽

...

Keyword(s):

Progenitor Cells ◽

Ex Vivo ◽

Virus Entry ◽

Parvovirus B19 ◽

Erythropoietin Receptor ◽

Receptor Expression ◽

Janus Kinase ◽

Erythroid Progenitor ◽

Erythroid Progenitor Cells

ABSTRACT Parvovirus B19 (B19V) infection is highly restricted to human erythroid progenitor cells. Although previous studies have led to the theory that the basis of this tropism is receptor expression, this has been questioned by more recent observation. In the study reported here, we have investigated the basis of this tropism, and a potential role of erythropoietin (Epo) signaling, in erythroid progenitor cells (EPCs) expanded ex vivo from CD34+ hematopoietic cells in the absence of Epo (CD36+/Epo− EPCs). We show, first, that CD36+/Epo− EPCs do not support B19V replication, in spite of B19V entry, but Epo exposure either prior to infection or after virus entry enabled active B19V replication. Second, when Janus kinase 2 (Jak2) phosphorylation was inhibited using the inhibitor AG490, phosphorylation of the Epo receptor (EpoR) was also inhibited, and B19V replication in ex vivo-expanded erythroid progenitor cells exposed to Epo (CD36+/Epo+ EPCs) was abolished. Third, expression of constitutively active EpoR in CD36+/Epo− EPCs led to efficient B19V replication. Finally, B19V replication in CD36+/Epo+ EPCs required Epo, and the replication response was dose dependent. Our findings demonstrate that EpoR signaling is absolutely required for B19V replication in ex vivo-expanded erythroid progenitor cells after initial virus entry and at least partly accounts for the remarkable tropism of B19V infection for human erythroid progenitors.

Download Full-text

Expression and function of receptors for stem cell factor and erythropoietin during lineage commitment of human hematopoietic progenitor cells

Blood ◽

10.1182/blood.v88.5.1594.bloodjournal8851594 ◽

1996 ◽

Vol 88 (5) ◽

pp. 1594-1607 ◽

Cited By ~ 1

Author(s):

J Olweus ◽

LW Terstappen ◽

PA Thompson ◽

F Lund-Johansen

Keyword(s):

Stem Cell ◽

Progenitor Cells ◽

Stem Cell Factor ◽

Progenitor Cell ◽

High Sensitivity ◽

Receptor Expression ◽

Erythroid Progenitor ◽

Erythroid Progenitor Cells ◽

Fluorescence Measurements ◽

And Function

The aim of the present study was to determine whether stem cell factor (SCF) and erythropoietin (EPO) act differently on defined subsets of progenitor cells, and if potential differences correlate with the receptor density on each subset. To investigate this possibility directly, we optimized conditions for the identification and purification of homogeneous progenitor cell subpopulations from human bone marrow. Populations containing 40% and 44% colony forming cells (CFCs) with 99% and 95% purity for the granulomonocytic and erythroid lineage, respectively, were sorted on the basis of differential expression of CD34, CD64, and CD71. In addition, a population containing 67% CFCs, of which 29–43% were CFU-MIX, was sorted from CD34hi CD38loCD50+ cells. Purified progenitor cell subsets were compared directly for responsiveness to SCF and EPO using a short-term proliferation assay. Expression of the receptors for SCF and EPO were then examined on each subset using a flow cytometer modified for high- sensitivity fluorescence measurements. The results show that EPO induces extensive proliferation of erythroid progenitor cells, but has no effect on the proliferation or survival of primitive or granulomonocytic progenitors, even when used in combination with other cytokines. The majority of erythroid progenitor cells furthermore stained positively with anti-EPO receptor (EPO-R) monoclonal antibodies, whereas other progenitor cells were negative. SCF alone induced extensive proliferation of erythroid progenitor cells, and had a stronger synergistic effect on primitive than on granulo-monocytic progenitors. In spite of these differences in SCF activity, there were no significant differences in SCF-R expression between the progenitor subsets. These results suggest that the selective action of EPO on erythropoiesis is determined by lineage-restricted receptor expression, whereas there are additional cell-type specific factors that influence progenitor cell responses to SCF.

Download Full-text

Regulation of Cellular Iron Metabolism by Erythropoietin: Activation of Iron-Regulatory Protein and Upregulation of Transferrin Receptor Expression in Erythroid Cells

Blood ◽

10.1182/blood.v89.2.680 ◽

1997 ◽

Vol 89 (2) ◽

pp. 680-687 ◽

Cited By ~ 92

Author(s):

Günter Weiss ◽

Tracey Houston ◽

Stefan Kastner ◽

Karin Jöhrer ◽

Kurt Grünewald ◽

...

Keyword(s):

Progenitor Cells ◽

Iron Metabolism ◽

Transferrin Receptor ◽

Regulatory Protein ◽

Receptor Expression ◽

General Mechanism ◽

Iron Regulatory Protein ◽

Erythroid Progenitor ◽

Cellular Iron ◽

Erythroid Progenitor Cells

Abstract Erythropoietin (Epo) is the central regulator of red blood cell production and acts primarily by inducing proliferation and differentiation of erythroid progenitor cells. Because a sufficient supply of iron is a prerequisite for erythroid proliferation and hemoglobin synthesis, we have investigated whether Epo can regulate cellular iron metabolism. We present here a novel biologic function of Epo, namely as a potential modulator of cellular iron homeostasis. We show that, in human (K562) and murine erythroleukemic cells (MEL), Epo enhances the binding affinity of iron-regulatory protein (IRP)-1, the central regulator of cellular iron metabolism, to specific RNA stem-loop structures, known as iron-responsive elements (IREs). Activation of IRP-1 by Epo is associated with a marked increase in transferrin receptor (trf-rec) mRNA levels in K562 and MEL, enhanced cell surface expression of trf-recs, and increased uptake of iron into cells. These findings are in agreement with the well-established mechanism whereby high-affinity binding of IRPs to IREs stabilizes trf-rec mRNA by protecting it from degradation by a specific RNase. The effects of Epo on IRE-binding of IRPs were not observed in human myelomonocytic cells (THP-1), which indicates that this response to Epo is not a general mechanism observed in all cells but is likely to be erythroid-specific. Our results provide evidence for a direct functional connection between Epo biology and iron metabolism by which Epo increases iron uptake into erythroid progenitor cells via posttranscriptional induction of trf-rec expression. Our data suggest that sequential administration of Epo and iron might improve the response to Epo therapy in some anemias.

Download Full-text

Role of NF-kappa B in regulation of apoptosis of erythroid progenitor cells

European Journal Of Haematology ◽

10.1111/j.1600-0609.2004.00400.x ◽

2005 ◽

Vol 74 (4) ◽

pp. 315-323 ◽

Cited By ~ 9

Author(s):

N. Sae-ung ◽

T. Matsushima ◽

I. Choi ◽

Y. Abe ◽

P. Winichagoon ◽

...

Keyword(s):

Progenitor Cells ◽

Nf Kappa B ◽

Erythroid Progenitor ◽

Erythroid Progenitor Cells

Download Full-text

Expression and function of receptors for stem cell factor and erythropoietin during lineage commitment of human hematopoietic progenitor cells

Blood ◽

10.1182/blood.v88.5.1594.1594 ◽

1996 ◽

Vol 88 (5) ◽

pp. 1594-1607 ◽

Cited By ~ 38

Author(s):

J Olweus ◽

LW Terstappen ◽

PA Thompson ◽

F Lund-Johansen

Keyword(s):

Stem Cell ◽

Progenitor Cells ◽

Stem Cell Factor ◽

Progenitor Cell ◽

High Sensitivity ◽

Receptor Expression ◽

Erythroid Progenitor ◽

Erythroid Progenitor Cells ◽

Fluorescence Measurements ◽

And Function

Abstract The aim of the present study was to determine whether stem cell factor (SCF) and erythropoietin (EPO) act differently on defined subsets of progenitor cells, and if potential differences correlate with the receptor density on each subset. To investigate this possibility directly, we optimized conditions for the identification and purification of homogeneous progenitor cell subpopulations from human bone marrow. Populations containing 40% and 44% colony forming cells (CFCs) with 99% and 95% purity for the granulomonocytic and erythroid lineage, respectively, were sorted on the basis of differential expression of CD34, CD64, and CD71. In addition, a population containing 67% CFCs, of which 29–43% were CFU-MIX, was sorted from CD34hi CD38loCD50+ cells. Purified progenitor cell subsets were compared directly for responsiveness to SCF and EPO using a short-term proliferation assay. Expression of the receptors for SCF and EPO were then examined on each subset using a flow cytometer modified for high- sensitivity fluorescence measurements. The results show that EPO induces extensive proliferation of erythroid progenitor cells, but has no effect on the proliferation or survival of primitive or granulomonocytic progenitors, even when used in combination with other cytokines. The majority of erythroid progenitor cells furthermore stained positively with anti-EPO receptor (EPO-R) monoclonal antibodies, whereas other progenitor cells were negative. SCF alone induced extensive proliferation of erythroid progenitor cells, and had a stronger synergistic effect on primitive than on granulo-monocytic progenitors. In spite of these differences in SCF activity, there were no significant differences in SCF-R expression between the progenitor subsets. These results suggest that the selective action of EPO on erythropoiesis is determined by lineage-restricted receptor expression, whereas there are additional cell-type specific factors that influence progenitor cell responses to SCF.

Download Full-text

The Role of Tyrosine Phosphorylation in Proliferation and Maturation of Erythroid Progenitor Cells. Signals Emanating from the Erythropoietin Receptor

European Journal of Biochemistry ◽

10.1111/j.1432-1033.1997.t01-1-00637.x ◽

1997 ◽

Vol 249 (3) ◽

pp. 637-647 ◽

Cited By ~ 89

Author(s):

Ursula Klingmuller

Keyword(s):

Progenitor Cells ◽

Tyrosine Phosphorylation ◽

Erythropoietin Receptor ◽

Erythroid Progenitor ◽

Erythroid Progenitor Cells

Download Full-text

Rapid induction of mouse virus-like (VL30) element transcripts by erythropoietin in murine erythroid progenitor cells

Blood ◽

10.1182/blood.v82.1.77.bloodjournal82177 ◽

1993 ◽

Vol 82 (1) ◽

pp. 77-83 ◽

Cited By ~ 7

Author(s):

DJ Park ◽

RW Lim ◽

HD Kim

Keyword(s):

Progenitor Cells ◽

Kinase Inhibitor ◽

Cdna Probe ◽

Erythroid Progenitor ◽

Rapid Induction ◽

Erythroid Progenitor Cells ◽

Hybridization Procedure ◽

Mouse Virus

We examined the activation of genes induced by erythropoietin (Epo) in erythroid progenitor cells that were isolated from the spleens of mice infected with anemia-inducing strain of the Friend virus. These erythroid progenitor cells, termed FVA cells, undergo in vitro differentiation to erythrocytes under the influence of Epo within 2 to 3 days. We used a differential hybridization procedure to screen a cDNA library constructed from FVA cells that were treated with Epo 2U/mL in the absence of serum for 2 hours. Of 20,000 recombinant phages, 47 plaques hybridized preferentially to cDNA probe prepared from Epo- stimulated cells. We found at least three different Epo-responsive genes (ERGs) and one of them corresponds to the mouse virus-like (VL30) element, similar to already reported BVL-1. The induction of VL30, which was evident within 30 minutes after Epo exposure, reached a maximum by 1 hour and remained stable for up to 4 hours. The treatment of FVA cells with cycloheximide (CHX) 10 micrograms/mL, which in itself activates the expression of VL30 caused a superinduction of the Epo signal. Changes in intracellular Ca2+ concentrations, either raised by ionomycin or depleted by EGTA, had no effect on the Epo-induced VL30 expression. In addition, protein kinase C (PKC) inhibitors such as staurosporine (3 mumol/L) or H7 (20 mumol/L) and a tyrosine kinase inhibitor, genistein (200 mumol/L), did not inhibit the Epo-induced expression of VL30. TPA (100 ng/mL), a PKC agonist, did not induce VL30 expression. Although the physiologic role of VL30 in the differentiation of erythroid progenitor cells is not known, our findings demonstrate that VL30 is an early ERG, and may be a useful indicator of the initial molecular actions of Epo.

Download Full-text

Combined action of c-kit and erythropoietin on erythroid progenitor cells

Development ◽

10.1242/dev.114.1.245 ◽

1992 ◽

Vol 114 (1) ◽

pp. 245-252

Author(s):

O. Ohneda ◽

N. Yanai ◽

M. Obinata

Keyword(s):

Progenitor Cells ◽

Early Phase ◽

Friend Virus ◽

Erythroid Progenitors ◽

Erythroid Progenitor ◽

Erythroid Progenitor Cells ◽

Large Colony ◽

Kit Gene ◽

Combined Action

Mutations at the murine dominant-white spotting locus (W) (c-kit) affect various aspects of hematopoiesis. We have made antibodies against c-Kit with the synthetic peptides deduced from the murine c-kit gene and examined the role of c-Kit in erythropoiesis. The antibody inhibited the stromal cell-dependent large colony formation of the erythroid progenitors. In the culture of erythropoietin-responsive erythroid progenitors of the anemia-inducing Friend virus-infected mouse spleen, the antibody inhibited only proliferation, but not differentiation of the progenitor cells. The inhibition was effective only at the early phase (within 6 hours after erythropoietin addition) before the cells start to proliferate induced by erythropoietin. During the early phase, erythropoietin down-regulated c-kit gene expression. These results suggest a mechanism of combined action of c-Kit with erythropoietin on the lineage-restricted erythroid progenitor cells.

Download Full-text