ABSTRACT
In order to elucidate the role of c-myb gene in erythroid differentiation of K562 cell induced by hemin (Hm) and erythropoietin (Epo), we constructed recombinant plasmid that could produce antisense myb RNA after induction with dexamethasone. During treatment with Hm, K562 cells constitutively expressed c-myb mRNA, and 50% of them began to synthesize hemoglobin (Hb). Expression of antisense myb RNA reduced the amount of c-myb mRNA, and the percentage of Hb-synthesizing cells was decreased to 20%. In the presence of Epo, c-myb mRNA declined and 20% of K562 cells synthesized Hb regardless of antisense myb RNA expression. It is suggested that constitutive expression of c-myb mRNA is necessary for Hm-induced differentiation, and that a decrease in the amount of c-myb mRNA induced by antisense myb RNA expression suppresses Hm-induced differentiation. The amount of c-myb mRNA in K562 cells was reduced during the differentiation induced by Epo. Expression of GATA-1 mRNA was almost constant during Hm-induced differentiation, but increased during Epo treatment. It is supposed that the mechanism of Hm-induced differentiation is distinguished from that of Epo-induced differentiation in K562 cells.
