Vitamin D decreases silencer methylation to downregulate renin gene expression.

Renin, encoded by REN, is an essential enzyme in the renin-angiotensin aldosterone system (RAAS) which is responsible for the maintenance of blood pressure homeostasis. Transcriptional regulation of REN has been linked to enhancer-promoter crosstalk, cAMP response element-binding protein (CREB), the active metabolite of vitamin D, 1,25-dihydroxyvitamin D3 (1,25(OH)2 D3 ), and a less well-characterized intronic silencer element. We hypothesized that in addition to these, differential DNA methylation is linked to REN expression and influenced by 1,25(OH)2 D3 . REN expressing cells (HEK293) were used to elucidate the effect of 1,25(OH)2 D3 on REN methylation and expression as quantified by methylation-sensitive qPCR and RT-qPCR, respectively. In vitro 1,25(OH)2 D3 supplementation (10 nM) induced significant hypomethylation of the REN silencer (P < 0.050), which was linked to a significant reduction in REN expression (P < 0.010) but had no effect on enhancer methylation. In addition, 1,25(OH)2 D3 increased VDR (P < 0.05), as well as TET1 (P < 0.05) expression, suggesting an association between 1,25(OH)2 D3 and DNA methylation. Thus, it appears that the silencer element, which is controlled by DNA methylation and influenced by 1,25(OH)2 D3 , plays an essential role in regulating REN expression.