Characterization of a hormone response element in the mouse N-acetyltransferase 2 (Nat2*) promoter

Multiple variant alleles of the human arylamine N-acetyltransferase genes, NAT1* and NAT2*, alter the capacity of individuals to metabolize arylamines by N-acetylation. Although biochemical and genetic studies have improved our understanding of the molecular basis of the acetylation polymorphism in humans and other mammals, regulation of NAT* gene expression is not understood. In the present study, a segment of the 5'-untranslated region of mouse Nat2* was sequenced and characterized. Primer extension analysis and RNase protection assays exposed multiple transcription initiation sites located 112 to 151 bases upstream of the translational start site. Computer sequence analysis revealed a promoter-like region located within the region 530 bases upstream of the translational start site consisting of TATA boxes, upstream promoter elements such as a CAAT box and Sp1 binding site, regulatory elements such as a palindromic hormone response element (HRE), and enhancer regions such as an AP-1 transcription factor binding site. Transient expression of CAT reporter constructs of the mouse Nat2*-palindromic HRE demonstrated positive regulation of the HSV-thymidine kinase 1 (tk1) promoter and induced the expression of chloramphenicol acetyltransferase (CAT). This induction was initiated by the addition of hormones such as 5alpha-dihydrotestosterone (DHT) or dexamethasone and was entirely dependent on the presence of androgen or glucocorticoid receptors, respectively. Together with recent discoveries regarding the effects of testosterone on the expression of Nat2* in mouse kidney during development, the findings reported in this article suggest that the HRE found in the promoter region of Nat2* is a potential candidate for the mediation of androgenic regulation of Nat2* in mouse kidney.