The type 2 CD10/neutral endopeptidase 24.11 promoter: functional characterization and tissue-specific regulation by CBF/NF-Y isoforms.

The cell surface zinc metalloproteinase CD10/neutral endopeptidase 24.11 ([NEP] neprilysin) functions as part of a regulatory loop to control local concentrations of peptide substrates and associated peptide-mediated signal transduction. The physiologic role of the enzyme depends on available substrates in specific organs and cell types. Although CD10/NEP is expressed on a restricted subset of normal and malignant lymphoid progenitors, the enzyme is also expressed by a variety of epithelial cells. To explore the mechanism of tissue-specific expression of this regulatory enzyme, we characterized the major (type 2) CD10/NEP promoter and identified three functionally active transcription factor binding sites (regions I to III). CBF/NF-Y binds to the inverted CCAAT box in region I, whereas a second positive and a third negative factor bind to regions II and III, respectively. Although region I is required for maximal CD10/NEP-driven luciferase activity in the examined epithelial cell lines, this region is not required for maximal activity in the evaluated lymphoid cell lines. The apparent tissue-specific differences in requirements for region I (and CBF/NF-Y) are of particular interest because lymphoid and epithelial cells express alternatively spliced versions of CBF/NF-Y that differ in biologic activity.