The miR-125a/b-5p/circVAPA /SP1 axis plays a key role in regulating ACE2 expression in hypertension

RNAs within the renin-angiotensin system (RAS) have been recognized as critical regulators in hypertension and cardiovascular disease pathogenesis. However, the specific roles of regulatory RNAs, such as long non-coding RNA like circular RNAs, in regulating the RAS remain largely unexplored. We recently identified notable changes in miR-125a/b-5p from RNA-seq data of plasma and cerebrospinal fluid in a DOCA-salt hypertensive mouse model across both sexes. VAPA circular RNA (circVAPA) is a non-coding RNA molecule derived from the vesicle-associated membrane protein-associated protein A (VAPA) gene, functioning as a molecular sponge to modulate microRNA activity. The expression of circVAPA, assessed by q-RTPCR was significantly reduced, notably in males DOCA-salt mice (1±0.01 vs. 0.58±0.03, p<0.05). RNase R exonuclease resistance, as verified by ddPCR, confirmed the stable circular structure characteristic of circVAPA. The functional role of circVAPA was further characterized through techniques including Western capillary electrophoresis, dual-luciferase reporter assays, and co-immunoprecipitation. Our results demonstrate that miR-125a/b-5p mimics reduce ACE2 (1.99±0.17 vs.0.89±0.03, p<0.01) and SP1 (1.2±0.03 vs. 0.8±0.03, p<0.001) protein expression. Similarly, circVAPA knockdown reduced ACE2 and SP1 protein expression levels by increasing miR-125a/b-5p expression levels (1.2±0.03 vs. 0.86±0.04, p<0.01). Using JASPAR, SP1 binding motifs were identified in both ACE2 and VAPA promoter regions and a dual-luciferase reporter assay indicated that both hsp-SP1 (0.6±0.11 vs. 2.2±0.44, p<0.05) and hsp-ACE2 (9.6±0.66 vs.6.6±0.23, p<0.01) are likely primary targets of miR-125a/b-5p. We speculate that circVAPA could function as a circRNA contributing to blood pressure regulation by serving as a molecular sponge for miR-125a/b-5p. This interaction would increase ACE2 expression and enhance SP1's activity as a transcription factor, thereby promoting the transcription of ACE2 mRNA. These findings provide a foundation for developing potential therapeutic protocols targeting miR-125a/b-5p inhibition for the treatment of resistant hypertension. This work was supported in part by a research grant from the National Institutes of Health (HL163588). This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.