A 346-base pair region of the mouse γ-glutamyl transpeptidase Type II promoter contains sufficient cis-acting elements for kidney-restricted expression in transgenic mice

The mouse γ-glutamyl transpeptidase (GGT) gene encodes seven distinct mRNAs that are transcribed from seven separate promoters. Type II mRNA is the most abundant in kidney. We have developed a cell line with features of renal proximal tubular cells which expresses GGT mRNA types with a pattern similar to that of mouse kidney. Because a 346-bp sequence from the type II promoter directed the highest level of CAT activity in these cells, this region was used to drive the expression of a β-galactosidase reporter gene in transgenic mice. Two transgenic mouse lines expressed β-galactosidase limited to the renal proximal tubules. Site-directed deletions within this 346-bp promoter region demonstrated that cis-elements containing the consensus binding sites for AP2, a glucocorticoid response element (GRE)- like element, and the initiator region were required for transcriptional activity and were not additive. Purified AP2 bound and footprinted the AP2 consensus region, making it likely that transcription from the GGT type II promoter is regulated in part by AP2. These data suggest that transcription of the type II promoter requires multiple protein DNA interactions involving at least an AP2 element, and probably a GRE-like element and the initiator region.