Transcriptional regulation of the human eosinophil peroxidase genes: characterization of a peroxidase promoter.

The molecular basis for commitment of progenitors to the eosinophil lineage and mechanisms by which eosinophil-specific genes are expressed and regulated during differentiation is unknown. Expression of eosinophil peroxidase (EPO) is restricted to the eosinophil lineage. To understand the mechanisms involved in transcriptional regulation of EPO gene expression, we cloned the region of the EPO gene upstream of the transcriptional start site and analyzed the cis-acting elements required for EPO promoter activity in an eosinophil-inducible leukemic cell line, HL60-C15. The -1.5 kb EPO-pXP2 promoter construct reproducibly expressed > 120-fold more luciferase activity than did promoterless pXP2, and a 12-fold decrease in promoter activity was obtained when sequences between -122 and -45 bp were deleted. To further characterize regulatory sequences important for promoter activity, we performed linker-scanning analysis on the -122 to -45 bp region and identified a number of positively and negatively acting elements in the promoter.