Citations

Introduction: Previously, miR-425 have been implicated in the inhibition of the cardiac natriuretic peptide (NP) ANP gene expression with their role on BNP undefined. The mechanism by which miR-425 modulates NP expression remains to be explored. In heart failure (HF), adrenergic and neurohormone pathways are aberrantly activated. Our goal was to investigate the role of miR-425 and its downstream target Cofilin 2 (CFL2) on ANP and BNP expression in human CV disease (CVD). Hypothesis: We hypothesized miR-425, via CFL2, supresses NPs expression in vitro. MiR-425, CFL2 and NP levels were also determined in CVD patients. Methods: In vitro, human cardiomyocytes (HCM) were treated with vehicle (Veh), catecholamine isoproterenol (ISO) and cytokine endothelin (ET), miR-425 mimic. Cells were transfected with CFL2 plasmid or CFL2 siRNA. Normal (NM, n=100), Hypertension (HTN, n=30) and Acute HF (AHF, n=74) cohorts were studied. A confirmatory cohort was recruited. Plasma NT-proBNP, miR-425 were measured. In left ventricles (LV) from NM or HF (n=5 each), NP, CFL2 and miR-425 expression were assessed. Data expressed as means±SEM. * p<0.05 vs NM or Veh. Results: In vitro in HCM, treatment with ISO or ET in HCM reduced miR-425 and elevated NP mRNA levels. Furthermore, miR-425 mimic reduced Nppa (Veh: 1.0±0.03, mimic: 0.7±0.02*) and Nppb levels (Veh: 1.0±0.03, mimic: 0.5±0.01*). We showed that a top predicted target of miR-425, CFL2, was also reduced by the mimic. Further, NP mRNA was elevated by CFL2 overexpression and reduced by the knockdown of CFL2. In humans, MiR-425 was lower in HTN and AHF patients (NM: 0.15±0.03, HTN: 0.03±0.005*, HF: 0.01±0.003*) than NM. MiR-425 negatively correlates with NT-proBNP in NM and AHF cohorts. Downregulation of miR-425 was validated in a second AHF cohort. Similarly, in HF LV tissues, miR-425 (NM: 2.5±0.5, HF: 1.0±0.5*) was lower than NM group, while CFL2 and NP gene and protein expression were increased. Conclusion: In vitro, cardiac stress hormones downregulate miR-425 and increase NP gene expression, potentially through a novel target, CFL2. In CVD patients, miR-425 is lower, accompanied by an elevation of CFL2 and NP. Our findings implicate the pathway of stress hormones/miR-425/CFL2/NP production in CVD.

The natriuretic peptide system (NPS) and renin-angiotensin-aldosterone system (RAAS) function oppositely at multiple levels. While it has long been suspected that angiotensin II (ANGII) may directly suppress NPS activity, no clear evidence to date supports this notion. This study was designed to systematically investigate ANGII–NPS interaction in humans, in vivo, and in vitro. Circulating atrial, b-type, and c-type natriuretic peptides (ANP, BNP, CNP), cyclic guanosine monophosphate (cGMP), and ANGII were simultaneously investigated in 128 human subjects. Prompted hypothesis was validated in vivo to determine the influence of ANGII on ANP actions. The underlying mechanisms were further explored via in vitro approaches. In humans, ANGII demonstrated an inverse relationship with ANP, BNP, and cGMP. In regression models predicting cGMP, adding ANGII levels and the interaction term between ANGII and natriuretic peptides increased the predictive accuracy of the base models constructed with either ANP or BNP, but not CNP. Importantly, stratified correlation analysis further revealed a positive association between cGMP and ANP or BNP only in subjects with low, but not high, ANGII levels. In rats, co-infusion of ANGII even at a physiological dose attenuated cGMP generation mediated by ANP infusion. In vitro, we found the suppressive effect of ANGII on ANP-stimulated cGMP requires the presence of ANGII type-1 (AT1) receptor and mechanistically involves protein kinase C (PKC), as this suppression can be substantially rescued by either valsartan (AT1 blocker) or Go6983 (PKC inhibitor). Using surface plasmon resonance (SPR), we showed ANGII has low binding affinity to the guanylyl cyclase A (GC-A) receptor compared to ANP or BNP. Our study reveals ANGII is a natural suppressor for the cGMP-generating action of GC-A via AT1/PKC dependent manner and highlights the importance of dual-targeting RAAS and NPS in maximizing beneficial properties of natriuretic peptides in cardiovascular protection.