title: Thrombopoietin has a differentiative effect on late-stage human erythropoiesis.
abstract: To further explore the mechanism of the effect of thrombopoietin (TPO) on erythropoiesis, we used a two-phase culture system to investigate the effect of TPO on late-stage human erythroid lineage differentiation. In serum-free suspension and semisolid cultures of human peripheral blood derived erythroid progenitors, TPO alone did not produce benzidine-positive cells. However, in serum-containing culture, TPO alone stimulated erythroid cell proliferation and differentiation, demonstrated by erythroid colony formation, production of benzidine-positive cells and haemoglobin (Hb) synthesis. Monoclonal anti-human erythropoietin antibody and anti-human erythropoietin receptor antibody completely abrogated the erythroid differentiative ability of TPO in the serum-containing systems. This implied that binding of EPO and EPO-R was essential for erythropoiesis and the resultant signal transduction may be augmented by the signals emanating from TPO-c-Mpl interaction. Experiment of withdrawal of TPO further demonstrated the involvement of TPO in late-stage erythropoiesis. RT-PCR results showed that there was EPO-R but not c-Mpl expression on developing erythroblasts induced by TPO in serum-containing system. Our results establish that TPO affects not only the proliferation of erythroid progenitors but also the differentiation of erythroid progenitors to mature erythroid cells.
authors.affiliation: Molecular and Clinical Hematology Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, USA.
authors.forename: W
authors.initials: W
authors.lastname: Liu
authors.forename: M
authors.initials: M
authors.lastname: Wang
authors.forename: D C
authors.initials: DC
authors.lastname: Tang
authors.forename: I
authors.initials: I
authors.lastname: Ding
authors.forename: G P
authors.initials: GP
authors.lastname: Rodgers
mesh_terms: D002454:Cell Differentiation; D002455:Cell Division; D002478:Cells, Cultured; D015672:Erythroid Precursor Cells / Q000166:cytology / Q000502:physiology*; D004920:Erythropoiesis / Q000502:physiology*; D006454:Hemoglobins / Q000096:biosynthesis; D006801:Humans; D008533:Megakaryocytes / Q000166:cytology / Q000502:physiology; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D013926:Thrombopoietin / Q000502:physiology*
chemical_list: D006454:Hemoglobins; D013926:Thrombopoietin