Background: MicroRNAs are small noncoding RNA molecules that play a critical role in
regulating physiological and disease processes. Recent studies have now recognized microRNAs as an
important player in cardiac arrhythmogenesis. Molecular insight into arrhythmogenic cardiomyopathy
(AC) has primarily focused on mutations in desmosome proteins. To our knowledge, models of AC
due to microRNA dysregulation have not been reported. Previously, we reported on miR-130a mediated
down-regulation of Connexin43.
Objective: Here, we investigate miR-130a-mediated translational repression of Desmocollin2 (DSC2),
as it has a predicted target site for miR-130a. DSC2 is an important protein for cell adhesion, which
has been shown to be dysregulated in human AC.
Method & Results: After induction of miR-130a, transgenic mice demonstrated right ventricular dilation.
Surface ECG revealed spontaneous premature ventricular complexes confirming an arrhythmogenic
phenotype in αMHC-miR130a mice. Using total protein from whole ventricular lysate, western
blot analysis demonstrated an 80% reduction in DSC2 levels in transgenic myocardium. Furthermore,
immunofluorescent staining confirmed downregulation of DSC2 in transgenic compared with
littermate control myocardium. In transgenic hearts, histologic findings revealed fibrosis and lipid accumulation
within both ventricles. To validate DSC2 as a direct target of miR-130a, we performed in
vitro target assays in 3T3 fibroblasts, known to express miR-130a. Using a luciferase reporter fused to
the 3UTR of DSC2 compared with a control, we found a 42% reduction in luciferase activity with the
DSC2 3UTR. This reduction was reversed upon selective inhibition of miR-130a.
Conclusion: Overexpression of miR-130a results in a disease phenotype characteristic of AC and
therefore, may serve as potential model for microRNA-induced AC.