Myomaker is regulated by miR-489 and miR-24-3p, and controls fusion of myoblasts in the gynogenetic blunt snout bream.

The fusion process of myoblasts constitutes a critical phase in skeletal muscle myogenesis. The recently identified transmembrane protein Myomaker, which is muscle-specific, plays an indispensable role in myoblast fusion. However, the regulatory mechanisms of its expression in gynogenetic fish remain unclear. Spermatozoa of the Chinese perch (Siniperca chuatsi, CP, ♂) were used to induce eggs of the blunt snout bream (Megalobrama amblycephala, BSB, ♀) to produce the gynogenetic blunt snout bream (GBSB) with inter-order species hybridization. In our investigation, combined prediction and dual luciferase analysis demonstrated direct targeting of the Myomaker 3'-UTR by the microRNA's miR-24-3p and miR-489. Following antagomiR-489 and antagomiR-24-3p injection into GBSB, muscle fibers exhibited increased diameter and nuclear content, while molecular analysis showed that Myomaker expression was promoted and expression of myogenic factors (Myf5, MyoD, MyoG) was inhibited. Our results indicate that the targeted repression of Myomaker expression via binding of miR-489 or miR-24-3p to its 3'-UTR is associated with the inhibition of myoblast fusion, thereby potentially contributing to the suppression of skeletal muscle proliferation in GBSB.