RESUMO
Based on the presence of a functional retinoic acid receptor/retinoid X receptor transcription factor binding sequence (hormone-responsive element) in the renin gene enhancer and on the fact that the peroxisome proliferator-activated receptors (PPARs) bind to DNA as heterodimers with retinoid X receptors, we speculated that PPARs are involved in the regulation of renin gene expression. To test this hypothesis, we used the human renin-producing cell line CaLu-6. Endogenous or pharmacological PPARgamma agonists (unsaturated fatty acids and thiazolidinediones, respectively) stimulated renin gene expression. Surprisingly, we found that PPARgamma targets a palindromic repeat with a 3-bp spacer (Pal3) in the proximal human renin promoter. Thus, renin is the first gene described with a functional Pal3 sequence. PPARgamma agonists also stimulated renin gene expression in cultured native juxtaglomerular cells, which are the main source of renin in vivo. In summary, PPARgamma was identified as a novel intracellular mediator involved in the upregulation of renin transcription.
