The transcription factors, termed signal transducers and activators of transcription (STATs), are activated in response to many cytokines. Erythropoietin (EPO) induces not only proliferation but also differentiation of erythroid progenitor cells. To investigate the role of STAT proteins in EPO-induced erythroid differentiation, we examined the activation of STAT proteins in EPO- or granulocyte-macroph age colony-stimulating factor (GM-CSF)-dependent human leukemic cell line UT-7 for growth, and its subline UT-7/GM, which can differentiate into erythroid cells in response to EPO. In UT-7 cells, both GM-CSF and EPO induced sis-inducible element (SIE) binding complexes and βcasein promoter (β-CAP)-binding complexes. In UT-7/GM cells, GMCSF induced both the SIE binding complex and β-CAP binding complex. EPO induced the β-CAP binding complex but not the SIE-binding complex even at a high concentration. In addition, GM-CSF inhibited EPO-induced erythroid differentiation in UT-7/GM cells, and GM-CSF induced the SIE binding complex in these cells even in the presence of EPO. Taken together, SIE-binding complex may negatively act on EPO-induced erythroid differentiation.
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|Published - 1996