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MicroRNAs (miRNAs) have recently emerged as important molecular entities in heart failure (HF) pathophysiology and diagnosis. To date, miR-155 and miR-425 have been implicated in the inhibition of the cardiac natriuretic peptide (NP) ANP gene with their role on BNP undefined. In HF, adrenergic and neurohormonal pathways are dysregulated. Our goal was to advance our understanding of the regulation of these two miRNAs and their predictive value in human HF.
We hypothesized that miR-155 and -425 levels are reduced in HF compared to normal subjects. We also investigated the molecular mechanisms of NPs expression regulated by the miR-425 and -155.
Normal (healthy, NM, n=100) and Acute HF (AHF, n=74) cohorts were studied. Two confirmatory cohorts were also recruited: NM (n=20) and AHF (n=28). Plasma NT-proBNP was measured. Plasma miR-155 and -425 expression were quantified with RT-PCR. In left ventricular myocardium (LV) from NM or HF (n=5 each), Nppa (ANP gene), Nppb (BNP gene), miR-155, and -425 expressions were measured. In vitro, human cardiomyocytes (HCM) were treated with vehicle (Veh), 10-4 M catecholamine isoproterenol (ISO) and 10-6 M cytokine endothelin (ET) which are known to be activated in HF, mimics of miR-155 or -425, followed by gene expression assessment. Data expressed as means±SEM. * p<0.05 vs NM or Veh.
MiR-155 and miR-425 were significantly lower in AHF patients (miR-155: NM: 1.8±0.29, HF: 0.13±0.02*), (miR-425: NM: 0.15±0.03, HF: 0.01±0.003*) than NM. The area under the curve (AUC) of the two miRNAs are 0.86 and 0.87 in AHF cohorts respectively (vs NT-proBNP 0.98). MiR-425 negatively correlates with NT-proBNP in AHF cohorts (r=-0.33*). Downregulation of both miRNAs were validated in a second AHF cohort. Similarly, in HF LV tissues, HF displayed lower miR-155 and miR-425 levels than NM group, while NP gene and protein expression were increased. In vitro, treatment with ISO or ET in HCM reduced miR-155, miR-425 levels and significantly elevated Nppa and Nppb levels. Furthermore in HCM, treatment with mimic of miR-425 reduced Nppa (Veh: 1.0±0.03, miR-425 mimic: 0.7±0.02*) and Nppb levels (Veh: 1.0±0.03, miR-425 mimic: 0.5±0.01*). We also demonstrated that apoptosis signal-regulating kinase 1 (ASK1) and Cofilin 2, which have been reported to enhance Nppa and Nppb expression, was also reduced by miR-425.
MiR-155 and miR-425 are reduced in HF, which may be one of the mechanisms contributing to an increase in circulating ANP and BNP. MiR-425 also displays a negative correlation with NT-proBNP. In vitro, cardiac stress hormones known to be activated in HF downregulate these 2 miRNAs and increase NP gene expression which provides further insight into mechanisms of NP activation in HF. The findings for the first time implicate the pathway of stress hormones/miR-425/NP production in human HF simulated in vitro and further our understanding of NP activation in HF. These studies also support biomarker value for miR-155 and miR-425 and the compensatory nature of this decline in HF.
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