Erythroid gene expression is differentially regulated by erythropoietin, haemin and delta-aminolaevulinic acid in UT-7 cells.
Erythropoietin (Epo) is essential for the later stages of erythropoiesis, acting to promote cell survival and proliferation, but its role in differentiation remains to be defined. The UT-7 cell line exhibits both erythroid and megakaryocytic characteristics and can be induced to differentiate along the erythroid pathway by Epo or the megakaryocytic pathway by phorbol myristic acetate. We have compared the effects of Epo and the chemical inducers, delta-aminolaevulinic acid (delta-ALA) and haemin on the differentiation capacity of UT-7 cells. Epo alone promoted relatively early events in erythroid maturation, without significant changes in haemoglobin production or morphology. GATA-2 and c-myb were down-regulated by Epo, and GATA-2 was further down-modulated by the inducers. Conversely, SCL expression was up-regulated by Epo and further increased by haemin and delta-ALA. Epo caused an increase in the proportion of cells expressing cell surface glycophorin A (GPA) and up-regulated beta- and gamma-globin by several fold. Both haemin and delta-ALA caused a de novo increase in alpha-globin expression as well as enhancing Epo-induced beta-globin expression, leading to a marked increase in haemoglobin production. These results suggest that haemoglobin production in UT-7 cells is limited by a deficiency of erythroid-specific aminolaevulinic acid synthase (ALAS-E) activity or globin synthesis as a consequence of their immaturity as a multipotential cell line.
McHale
C M
CM
Department of Haematology, The Queen's University of Belfast, Royal Victoria Hospital. c.mchale@qub.ac.uk
Winter
P C
PC
Lappin
T R
TR
D000622:Aminolevulinic Acid / Q000494:pharmacology*; D002454:Cell Differentiation / Q000187:drug effects; D048429:Cell Size; D002478:Cells, Cultured; D015672:Erythroid Precursor Cells / Q000166:cytology / Q000187:drug effects*; D004921:Erythropoietin / Q000494:pharmacology*; D015870:Gene Expression; D005914:Globins / Q000378:metabolism; D006427:Hemin / Q000494:pharmacology*; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D014157:Transcription Factors / Q000378:metabolism
D006454:Hemoglobins; D014157:Transcription Factors; D004921:Erythropoietin; D006427:Hemin; D000622:Aminolevulinic Acid; D005914:Globins