MicroRNA-29c affects zebrafish cardiac development via targeting Wnt4

As a single cardiac malformation, ventricular septal defect (VSD) is the most common form of congenital heart disease. However, the precise molecular mechanisms underlying VSD are not completely understood. Numerous microRNAs (miRs/miRNAs) are associated with ventricular septal defects. miR-29c inhibits the proliferation and promotes the apoptosis and differentiation of P19 embryonal carcinoma cells, possibly via suppressing Wnt4 signaling. However, to the best of our knowledge, no in vivo studies have been published to determine whether overexpression of miR-29c leads to developmental abnormalities. The present study was designed to observe the effect of miRNA-29c on cardiac development and its possible mechanism in vivo. Zebrafish embryos were microinjected with different doses (1, 1.6 and 2 µmol) miR-29c mimics or negative controls, and hatchability, mortality and cardiac malformation were subsequently observed. The results showed that in zebrafish embryos, miR-29c overexpression attenuated heart development in a dose-dependent manner, manifested by heart rate slowdown, pericardial edema and heart looping disorder. Further experiments showed that overexpression of miR-29c was associated with the Wnt4/β-catenin signaling pathway to regulate zebrafish embryonic heart development. In conclusion, the present results demonstrated that miR-29c regulated the lateral development and cardiac circulation of zebrafish embryo by targeting Wnt4.