A myeloid-lineage-specific enhancer upstream of the mouse myeloperoxidase (MPO) gene.

The myeloperoxidase (MPO) gene is selectively expressed during haemopoiesis in the granulocytic lineage. Compared with the erythroid (beta-globin) and B-cell (immunoglobulin) lineages, little is known of the regulatory sequences and transcription factors involved in the regulation of genes specific for granulopoiesis. We have approached this issue by identifying a strong enhancer for the murine MPO gene. A candidate enhancer region was mapped by the detection of a strong DNase I hypersensitive site, -3.4 to -3.2 kb upstream of the MPO gene. A 301 bp fragment encompassing the DNase I site was shown to have strong enhancer function in a transient assay following transfection of a reporter gene into a MPO-expressing cell (WEHI 3BD+), but was inactive in lymphoid cells. Analysis of sub-fragments revealed that the whole 301 bp fragment is required for maximal enhancer function.