Erythroid progenitors differentiate and mature in response to endogenous erythropoietin
Takeshi Sato, … , Kohichiro Tsuji, Tatsutoshi Nakahata
Takeshi Sato, … , Kohichiro Tsuji, Tatsutoshi Nakahata
Published January 15, 2000
Citation Information: J Clin Invest. 2000;106(2):263-270. https://doi.org/10.1172/JCI9361.
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Article

Erythroid progenitors differentiate and mature in response to endogenous erythropoietin

Abstract

We reported previously that stimulation of glycoprotein 130 (gp130) by a combination of human IL-6 and soluble IL-6 receptor (sIL-6R) could support proliferation, differentiation, and terminal maturation of erythroid cells in the absence of erythropoietin (EPO) from human CD34+ cells in culture with stem cell factor (SCF). This observation suggested that differentiation of hematopoietic stem/progenitor cells to erythroid cells progressed according to an intrinsic program and that EPO receptor (EPOR) could be replaced by other cytokine receptors. In other words, EPOR appeared to be dispensable for erythropoiesis. Here we examined the role of EPOR in erythropoiesis stimulated by SCF, sIL-6R, and IL-6. Surprisingly, reduction of EPOR expression using antisense oligodeoxynucleotides suppressed erythropoiesis stimulated not only by SCF and EPO, but also by SCF, sIL-6R, and IL-6. EPO mRNA was detected in erythroid cells but not myeloid cells cultured in the presence of SCF, sIL-6R, and IL-6. Furthermore, high concentrations of anti–EPO-neutralizing antibody abrogated erythropoiesis in cultures without exogenous EPO. Based on these results, we suggest that erythroid progenitors themselves secrete EPO and that they have the potential to differentiate and mature in response to this endogenous EPO.

Authors

Takeshi Sato, Taira Maekawa, Sumiko Watanabe, Kohichiro Tsuji, Tatsutoshi Nakahata

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Detection of EPO mRNA in cells stimulated by SCF and sIL-6R/IL-6. (a) Hu...
Detection of EPO mRNA in cells stimulated by SCF and sIL-6R/IL-6. (a) Human EPO cDNA and genomic DNA were amplified by PCR (33 cycles), and the PCR products were electrophoresed on a 7.5% polyacrylamide gel. The PCR products from hEPO cDNA and h-genomic DNA were 124 bp and 258 bp, respectively. Sizes of the markers are indicated on the left. (b) CB CD34+ cells were cultured in the presence of SCF and IL-6, with or without sIL-6R. After 14 days, the cells were harvested and cDNAs were synthesized after mRNA extraction. EPO mRNA was detected only in cells cultured with SCF and sIL-6R/IL-6 after 40 cycles of RT-PCR, and the sequences were confirmed.