Abstract 043: A Gwas Prioritized Candidate Gene,Nr2f2, Attenuates Salt-sensitive Hypertension and Associated Renal Function

Abstract

A haplotype-based re-analysis of the GWAS study by the Wellcome Trust Case Control consortium prioritized the transcription factor, Nuclear receptor2, family2 (NR2F2) also known as Chicken ovalbumin upstream promoter-transcription factor II (COUP-TFII) as a gene associated with essential hypertension in humans. This gene is also prioritized as a differentially expressed positional BP QTL candidate gene on rat chromosome 1. To further examine Nr2f2 as a determinant of blood pressure, a mutant Dahl salt-sensitive (S) rat model was generated using the zinc-finger nuclease (ZFN) technology. As a result of this ZFN mediated disruption, a 15-bp deletion occurred within exon 2 of the Nr2f2 locus, resulting in the loss of 5 amino acids from the hinge region of the Nr2f2 protein. Systolic BP of the homozygous Nr2f2mutant rats was lower than that of the S rats (179±3 vs. 197±5 mmHg; p<0.001) as measured by the tail-cuff method and (165±2 vs. 201±3 mmHg; p<0.001) as monitored by the radio-telemetry method. Nr2f2mutant rats demonstrated lower proteinuria compared to S rats (87.97±7.07 vs. 122.63±7.07mg/day; p<0.05). Since Nr2f2 is reported to negatively regulate renin promoter activity, we tested renin activity in the Nr2f2mutant rats. However, there was no significant difference in either the plasma renin activity or renal renin protein expression when compared with S rats. Renal histological analysis showed that Nr2f2mutant rats have decreased collagen compared with the S rats. Furthermore, Nr2f2mutant rats showed significantly decreased TGF-β protein levels, when compared with S rat kidney (p<0.05). These data, taken together with our recently published data on the improved cardiac and vascular function in the Nr2f2mutant rats (Nat Commun. 2015 Feb 17;6:6252), lend support to Nr2f2 as a determinant of blood pressure and associated renal function. While the observed improvement in renal function could be a secondary consequence of lower hypertension, our data, combined with the important mechanistic finding that the enhanced transcription factor-transcription factor interaction of Nr2f2 with Fog2 (Friend of GATA4), suggest that the hinge region of Nr2f2 is important for regulating blood pressure and associated cardiac and renal functions.