A 30-base pair element is responsible for the myeloid-specific activity of the human neutrophil elastase promoter

Human neutrophil elastase (HNE), a serine protease, is expressed only in the promyelocytic stages of granulocyte maturation. We examined several regions of the promoter for transcriptional activity and report that a 30-base pair (bp) element located between -76 and -106 in the 5'-flanking region of HNE is sufficient for myeloid-specific expression of HNE. Gel shift assays using nuclear extracts from myeloid and non-myeloid cells reveal several myeloid-specific complexes binding to the 30-bp element. Examination of DNA-protein interactions shows that at least two myeloid-specific proteins of 38 and 55 kDa bind to this element. DNase I protection analysis reveals two distinct footprints between -80 to -91 and -94 to -104 within this element. Transient expression studies using deletion constructs of the HNE 5'-flanking region show that the 30-bp element is active in myeloid cells K 562 and U 937 but not in HeLa cells. Internal deletion of this element results in a 60-85% loss of promoter activity in myeloid cells. Additional functional studies also show that a 19-bp region between -112 and -131 contributes to transcriptional activity of the elastase promoter as well.