Defective zebrafish heart regeneration following depletion of let-7

The adult zebrafish is capable of regenerating heart muscle, resolving collagen tissue and fully restoring heart function throughout its life. The goal of this study was to investigate how the highly upregulated, epicardium-enriched microRNA let-7i functions in wound closure and cardiomyocyte proliferation. We found that depletion of let-7 in adult zebrafish using locked-nucleic acid (LNA) antisense oligonucleotides results in defective heart regeneration. We assayed gene expression at 7 days post ventricular resection in LNA-scrambled and LNA-anti-let-7 treated adult zebrafish to determine the role of let-7 during heart regeneration.