The myeloid-lineage specific enhancer of the mouse myeloperoxidase gene consists of three cis-elements defined as in vitro DNase I footprints.

The myeloid-lineage specific enhancer at 3.4-3.1 kb upstream of the mouse myeloperoxidase gene [1] has been further characterised. In vitro DNase I footprinting experiments revealed three protected sequences (FT-I, -II and -III) in the enhancer, associated with the proteins that are enriched in WEHI 3BD+ cells, at which the MPO gene is highly expressed; but not in two non-MPO expressing lymphocytic cell lines. Site-specific mutations at each element severely reduced the level of the reporter gene activity in a non-additive manner. This is parallel with either abolishment or alteration of the corresponding wild-type protein-DNA interaction in vitro. Consideration of the sequence motifs present in the enhancer suggests that the cis-elements defined as the in vitro DNase I footprints are likely to be novel.