Figure 1.

RBP-J regulates the renin promoter in vivo. Mutation of the RBP-J site in the renin promoter diminishes GFP expression, a surrogate of renin expression. (A) Diagram of the BAC reporter construct used to generate BAC transgenic mice. The dual kanamycin/streptomycin selection strategy was used to replace the first exon of renin with enhanced GFP, insert the renin gene 3′ untranslated region (UTR), and modify the RBP-J binding site (nucleotides are in red). (B) Quantitative RT-PCR for GFP mRNA expression in kidneys from mice harboring the mutated RBP-J reporter (Mut-BAC) is significantly lower than in the control (WT-BAC) mice at basal state. (C–F) Mice were treated with low sodium diet+captopril for 5 days to induce re-expression of renin along arterioles. (C) Mut-BAC mice do not increase GFP mRNA to the same level as WT-BAC mice. (D and E) Immunohistochemistry for GFP and renin expression in response to homeostatic challenge. (D) In WT-BAC mice, GFP (brown) is in JG cells, small arterioles, and along the arterioles, recapitulating the renin pattern. Mut-BAC mice have no GFP along the arterioles and few GFP-positive JGAs (arrows). (E) Renin staining in WT-BAC and Mut-BAC mice shows that, as expected, the endogenous, nonmutated renin gene responds by increasing the number of renin-positive cells along the arterioles properly and equally in both groups. *Glomeruli with GFP-positive or renin-positive JGA. (F) The JGA index for renin in both transgenic mice shows that harboring the BAC transgene does not affect expression of the endogenous renin gene. Values are means±SEMs. **P<0.01; ***P<0.001.