Regulation of renin expression by the orphan nuclear receptors Nr2f2 and Nr2f6

Abstract

Understanding the transcriptional mechanisms of renin expression is key to understanding the regulation of the renin-angiotensin system. We previously identified the nuclear receptors RAR/RXR and Nr2f6 (EAR2) as positive and negative transcriptional regulators of renin expression, respectively (Liu X, Huang X, Sigmund CD. Circ Res 92: 1033-1040, 2003). Both mediate their effects through a hormone response element (HRE) within the renin enhancer. Here, we determined whether another nuclear receptor, Nr2f2 (Coup-TFII, Arp-1), identified in a screen of proteins that bind the HRE, also regulates renin expression. Luciferase assays indicate that Nr2f2 negatively regulates the renin promoter more potently than Nr2f6. Gel-shift and chromatin immunoprecipitation (ChIP) indicate that Nr2f2 and Nr2f6 can bind directly to the renin enhancer through the HRE. Surprisingly, baseline expression of endogenous renin was not effected when Nr2f2 was knocked down in As4.1 cells, whereas knockdown of Nr2f6 increased renin expression twofold. Interestingly, however, knockdown of Nr2f2 augmented the induction of renin expression caused by retinoic acid. These data indicate that both Nr2f6 and Nr2f2 can negatively regulate the renin promoter, under baseline conditions and in response to physiological queues, respectively. Therefore, Nr2f2 may require an initiating signal that results in a change at the chromatin level or activation of another transcription factor to exert its effects. We conclude that both Nr2f2 and Nr2f6 negatively regulate renin promoter activity, but may do so by divergent mechanisms.

Advances in Blood Pressure Genomics

“…The sentinel SNP is annotated within a CCCTC-binding factor-binding site, identified by ChIP-seq. We note that the CCCTC-binding factor has also been shown to regulate the renin gene 71 and the angiotensinconverting enzyme 2 gene, 72 CCCTC-binding factor-binding sites are ubiquitous in the genome; however, this regulatory mechanism might be worth further investigation. By contrast, Online Figure II shows how ENCODE can highlight evidence of cell-type-specific regulatory elements.…”

Estrogen Receptor α Is Required for Maintaining Baseline Renin Expression

“…22 Multiple studies have shown that VDR, Nr2f2, and Nr2f6 are negative regulators of renin expression. 16,19,23,24 To date, however, there is no report on the role of Hnf4α and ERα in regulating renin expression. We first determined whether these two nuclear receptors are expressed in the renin-expressing As4.1 cells.…”

“…A probe where the critical nucleotides in the HRE were mutated was used as a control. 19 ERα protein was detected in proteins eluted from the WT probe but not from the MUT probe, signifying that ERα is able to bind to the HRE sequence with high specificity (Figure 4A). Nr2f2 served as the positive control since we showed it can bind to the HRE in previous studies.…”

“…14 We also reported that two orphan nuclear receptors, Nr2f6 and Nr2f2 also bind to the HRE, but unlike RAR/RXR, both of these nuclear receptors negatively regulated renin transcription. 19 These studies led to the conclusion that both positive and negative regulators bind to the HRE. The most promoter proximal binding site, Ea, matches the canonical binding sequence for nuclear factor-Y (NF-Y) and partially overlaps with the HRE.…”

Chicken Ovalbumin Upstream Promoter Transcription Factor II Regulates Renin Gene Expression

“…Interestingly, COUP-TFII was identified as a yeast onehybrid screen hit with the enhancer HRE and As4.1 cell nuclear extracts (33). Recently, the interaction of COUP-TFII with the renin enhancer HRE repeat was confirmed (35). COUP-TFII is an orphan nuclear receptor that could regulate the expression of its target genes either positively or negatively (29).…”