MECHANISM OF CAMP REGULATION OF RENIN GENE-TRANSCRIPTION BY PROXIMAL PROMOTER

Renin is produced mainly by the kidney, and cAMP is a main positive re gulator of its synthesis. This study was undertaken to analyze the mol ecular mechanism of cAMP-mediated regulation of Ren-1C gene transcript ion by the proximal promoter. We first showed that the promoter region from -365 to +16 of the mouse renin gene (Ren-1C) mediated the cAMP-i nduced chloramphenicol acetyltransferase gene expression in embryonic kidney-derived 293 cells. Deletion analysis and heterologous promoter assay disclosed that the proximal promoter region from -75 to +16 was able to activate chloramphenicol acetyltransferase expression by cAMP, and indicated that the proximal promoter element from -75 to -47 (RP- 2 element) overlapping the TATA-like region was able to confer cAMP re sponsiveness. Electrophoretic mobility shift assay and DNase I footpri nting analysis demonstrated that novel nuclear factors in 293 cells in teracted with the RP-2 element, and that cAMP increased the binding ac tivity of these nuclear factors to the RP-2 element. Furthermore, we d emonstrated that cAMP enhanced the binding of nuclear factors derived from juxtaglomerular cells, the main production site of renin in the k idney, to the RP-2 element in vivo. These results suggest that the RP- 2 element plays an important role in the cAMP-mediated regulation of R en-1C gene transcription through the proximal promoter.