Thrombopoietin supports in vitro erythroid differentiation via its specific receptor c-Mpl in a human leukemia cell line.
Thrombopoietin (TPO) acts on megakaryopoiesis and erythropoiesis in vitro and in vivo. We isolated a novel subline, UT-7/GMT, from the human leukemia cell line UT-7/GM (N. Komatsu, et al., Blood, 89: 4021-4033, 1997). A small population of UT-7/GM cells positively stained for hemoglobin (Hb) after a 7-day exposure to TPO. More than 50% of TPO-treated UT-7/GMT cells positively stained for Hb. Using UT-7/GMT cells, we examined how TPO promotes hemoglobinization. TPO induced tyrosine phosphorylation of the TPO receptor but not the erythropoietin (EPO) receptor. There was no competition between TPO and EPO for binding to EPO receptor. These findings suggest that TPO has a direct effect on hemoglobinization via a specific receptor on UT-7/GMT cells. Isoelectric focusing demonstrated that TPO induced fetal and adult Hb synthesis, whereas EPO induced embryonic, fetal, and adult Hb synthesis. Thus, our data suggest that TPO has a distinct action on erythropoiesis.
Yamada
M
M
Department of Medicine, Jichi Medical School, Tochigi, Japan.
Komatsu
N
N
Kirito
K
K
Kashii
Y
Y
Tomizuka
H
H
Okada
K
K
Endo
T
T
Fukumaki
Y
Y
Shinjo
K
K
Abe
K
K
Miura
Y
Y
D001667:Binding, Competitive; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D002454:Cell Differentiation; D004268:DNA-Binding Proteins / Q000378:metabolism; D015672:Erythroid Precursor Cells / Q000187:drug effects*; D050981:Erythroid-Specific DNA-Binding Factors; D004920:Erythropoiesis / Q000187:drug effects; D016193:G1 Phase / Q000187:drug effects; D050989:GATA2 Transcription Factor; D015870:Gene Expression / Q000187:drug effects; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D053614:Janus Kinase 2; D008894:Milk Proteins; D009363:Neoplasm Proteins; D010766:Phosphorylation / Q000187:drug effects; D011493:Protein Kinase C / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D018121:Receptors, Cytokine / Q000378:metabolism; D017467:Receptors, Erythropoietin / Q000378:metabolism; D053628:Receptors, Thrombopoietin; D050799:STAT5 Transcription Factor; D015398:Signal Transduction; D013926:Thrombopoietin / Q000494:pharmacology*; D015534:Trans-Activators / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism; D014407:Tumor Cells, Cultured
D004268:DNA-Binding Proteins; D050981:Erythroid-Specific DNA-Binding Factors; D050989:GATA2 Transcription Factor; C494711:GATA2 protein, human; D006454:Hemoglobins; D008894:Milk Proteins; D009363:Neoplasm Proteins; D011518:Proto-Oncogene Proteins; D018121:Receptors, Cytokine; D017467:Receptors, Erythropoietin; D053628:Receptors, Thrombopoietin; D050799:STAT5 Transcription Factor; D015534:Trans-Activators; D014157:Transcription Factors; C082218:MPL protein, human; D013926:Thrombopoietin; D011505:Protein-Tyrosine Kinases; C507924:JAK2 protein, human; D053614:Janus Kinase 2; D011493:Protein Kinase C; D017871:Calcium-Calmodulin-Dependent Protein Kinases