Tissue specificity of renin promoter activity and regulation in mice

Certain mouse strains (e.g., DBA/2) contain two renin genes (termed Ren-1 and Ren-2) and express higher renin levels in nonkidney tissues than strains with a single renin gene. The 5'-flanking regions of the Ren-1 and Ren-2 genes contain several TATA boxes preceding putative transcriptional start sites. These initiators are termed P1a, P1, P2 (from 5' to 3'), and their function (with the exception of P2) is largely unknown. In this study, we mapped the renin transcriptional start sites in renal and extrarenal tissues [adrenal, brain, testis, heart, and submandibular gland (SMG)] and examined the effect of adenosine 3',5'-cyclic monophosphate (cAMP) on tissue specific promoter usage. Our results showed that, in the unstimulated state, P2 (the predicted initiator) is active in all DBA/2 mouse tissues. Additional transcriptional start sites were detected in the adrenal and testis (originated by P1a and P2) and the SMG (originated by P1a, P1, and P2). The administration of 8-bromoadenosine 3',5'-cyclic monophosphate led to selective stimulation of P1a in the adrenal but did not affect the selective usage of initiation sites in other organs. A locus-specific ddNTP primer extension assay was used to verify which renin gene is induced by cAMP. Results indicated that both Ren-1 and Ren-2 responded to cAMP treatment in identical fashion. Taken together, these data indicate that more than one form of renin transcript is present in several mouse tissues. There is tissue specificity in promoter usage in the unstimulated state and in response to cAMP.