Studies of the constitutive expression of the mouse erythropoietin gene

The IW32 and NN10 cell lines are erythroleukemic cell lines which secrete erythropoietin (epo) into the culture medium constitutively. IW32 cells have a rearranged and amplified epo gene in addition to the normal gene. NN10 cells contain only the normal epo gene. DNase I hypersensitivity studies suggested that, in IW32 cells, it is the rearranged gene which is transcriptionally active. Sequence analysis of the upstream region of the rearranged epo gene suggests that the rearrangement has served to introduce a transcriptionally active gene close to the epo gene. This juxtaposition may explain the transcriptional activation of the epo gene at the rearranged locus.