Initial function analysis of a novel erythroid differentiation related gene EDRF1

Erythroid differentiation depends on the establishment of specific patterns of gene expression. Hypersensitive site 2 (HS2, serving as a major enhancer of globin genes)-binding proteins may be involved in its natural open chromosomal environment formation. Previously we prepared monoclonal antibodies against HS2-binding nuclear proteins of terminal differentiated erythroid cells. By utilizing the monoclonal antibodies, we screened λ-gt11 human fetal liver cDNA expression library and obtained one cDNA clone, which was named erythroid differentiation related gene (EDRF1, Genbank accession number AF040247), encompassing an entire open reading frame. We investigated the expression pattern of EDRF1 by RT-PCR technique. And a clue to the function of EDRF1 has been found from confirmation of high levels of EDRF1 mRNA in differentiated K562 and human fetal liver tissue. To illuminate the function of EDRF1 in K562 cells, sense and antisense EDRF1 constructs were prepared and transfected into K562 cells. α-globin mRNA was down-regulated and EpoR (erythropoietin receptor) mRNA expression was increased in antisense transfected cells. Cells transfected with sense construct grew more slowly than control cells suggested by [³H] thimidine incorporation experiments. Suppression of K562 proliferation was accompanied by increased spontaneous hemoglobin synthesis demonstrated by spectrometry. K562 cells transfected with sense construct exhibited reduced clongenicity compared with control cells in methycellulose culture. These data provided the evidence that EDRF1 can influence globin expression and hemoglobin synthesis in K562 cells and modulated self-renewal in K562 cells.