AMY-1 is a trigger for the erythrocyte differentiation of K562 cells

We have reported that a novel c-Myc binding protein, AMY-1, stimulated the transcription activity of c-Myc and was translocated from cytoplasm to nucl ei in a c-Myc-dependent manner. Here, the role of AMY-1 in cell differentia tion was examined. AMY-1 expression was up-regulated after differentiation induction of human K562 cells to erythrocyte cells by AraC, while c-Myc exp ression was rapidly downregulated. K562 cell lines expressing exogenous AMY -1 were established, and these cells expressed a high level of; E-globin mR NA, a marker gene necessary for erythrocyte cell differentiation, without d ifferentiation induction. The addition of AraC rapidly initiated differenti ation in these cell lines, which continued to differentiate to erythrocyte cells possessing a high level of hemoglobin even after the decrease in AMY- 1 expression. These results suggest that AMY-1 is a trigger for K562 cells to differentiate to erythrocyte cells and that AMY-1 may have a function in dependent of or different from c-Myc.