Roles of miR-196a and miR-196b in Zebrafish Motor Function

The exertion of motor function depends on various tissues, such as bones and muscles. miR-196 has been widely studied in cancer and other fields, but its effect on bone and skeletal muscle is rarely reported. In order to explore the role of miR-196 family in bone and skeletal muscle, we used the previously successfully constructed miR-196a-1 and miR-196b gene knockout zebrafish animal models for research.

miR-196a-1 and miR-196b play an important role in muscle fiber structure, bone mineral density, and bone trabecular quantity by affecting the expression of vcp, dpm1, acta1b, mylpfb, gdf6a, fgfr3, and col1a1a and then affect the function of the motor system.

The behavioral trajectories of zebrafish from 4 days post-fertilization (dpf) to 7 dpf were detected to analyze the effect of miR-196a-1 and miR-196b on motor ability. Hematoxylin-eosin (HE) staining and transmission electron microscopy (TEM) were used to detect the dorsal muscle tissue of zebrafish. The bone tissue of zebrafish was detected by microcomputed tomography (micro-CT). Real-time PCR was used to detect the expression levels of related genes, including vcp, dpm1, acta1b, mylpfb, col1a1a, bmp8a, gdf6a, and fgfr3.

The behavioral test showed that the total behavioral trajectory, movement time, and movement speed of zebrafish larvae were decreased in the miR-196a-1 and miR-196b gene knockout lines. Muscle tissue analysis showed that the structure of muscle fibers in the zebrafish lacking miR-196a-1 and miR-196b was abnormal and was characterized by vacuolar degeneration of muscle fibers, intranuclear migration, melanin deposition, and inflammatory cell infiltration. Bone CT examination revealed decreased bone mineral density and trabecular bone number. The real-time PCR results showed that the expression levels of vcp, dpm1, gdf6a, fgfr3, and col1a1a were decreased in the miR-196b gene knockout group. The expression levels of dpm1, acta1b, mylpfb, gdf6a, and col1a1a were decreased, and the expression level of fgfr3 was increased in the miR-196b gene knockout group compared with the wild-type group. Conclusions: miR-196a-1 and miR-196b play an important role in muscle fiber structure, bone mineral density, and bone trabecular quantity by affecting the expression of vcp, dpm1, acta1b, mylpfb, gdf6a, fgfr3, and col1a1a and then affect the function of the motor system.