Abstract 11740: Identification of a Mechanism vy Which Common Blood Pressure Genetic Variant in the Nppa Gene Regulates Anp Levels
The minor G allele of a common variant (rs5068, A/G) in the 3’ UTR of the gene encoding ANP is associated with reduced blood pressure in population genetic studies. We investigated the influence of rs5068 on plasma ANP levels before and after dietary salt loading and sought to identify the mechanism by which rs5068 regulates ANP levels. We enrolled 31 lean, normotensive subjects (23 AA and 8 AG genotype). Nt-proANP levels were measured after subjects completed a week of very low (230 mg/d) or high sodium (4600 mg/d) diet, in random order. Compared with AA subjects, AG subjects had higher Nt-proANP levels after both the low- (49%) and high-salt (32%) diets (p=0.016 for genotype effect). There was no evidence of a diet-by-genotype interaction. The difference in Nt-proANP levels by genotype was similar to the difference by diet (Fig 1A). We identified a microRNA (miR-425) predicted to match a 7 base pair sequence spanning rs5068 for the major but not the minor allele. miR-425 was detected in human atria and ventricles. In the 31 subjects, plasma miR-425 levels were greater on the low than on the high salt diet (2.8 vs. 0.8 pg/L, p=0.007). The ANP 3’UTR with major or minor rs5068 alleles was ligated to a luciferase reporter plasmid (major-LUC and minor-LUC, respectively). In COS cells, co-transfection of miR-425 reduced luciferase activity in major-LUC but not minor-LUC cells (Fig 1B). Co-transfection of an anti-miR-425 increased luciferase activity in major-LUC but not minor-LUC cells. In human HepG2 cells (AA genotype), transfection of miR-425 reduced ANP mRNA levels. In summary, the impact of rs5068 on circulating ANP is comparable to the change induced by a 20-fold increase in salt intake. Experimental studies demonstrate that the effect of rs5068 is mediated by miR-425, a novel miRNA that regulates ANP mRNA levels. These findings raise the possibility that, by increasing ANP production, anti-miR-425 could be used to treat disorders of salt overload such as hypertension and heart failure.
- © 2012 by American Heart Association, Inc.