The Role of Twist2 in Myoblast Proliferation, Fusion, and Its Impact on Muscle Structure During the Growth of Chinese Perch (Siniperca chuatsi)

<i>Twist2</i> plays a pivotal regulatory role in the growth of skeletal muscle across various organisms. Nonetheless, the specific mechanism by which <i>Twist2</i> governs skeletal muscle function in fish, particularly in the economically significant Chinese perch (<i>Siniperca chuatsi</i>), remains unclear. Within the muscle injury model in Chinese perch, we observed that <i>Twist2</i> expression was upregulated during the repair phase of fast muscle tissue, exhibiting an expression pattern analogous to that of <i>Pax7</i>. Following the knockdown of <i>Twist2</i> using <i>Twist2</i>-specific in vivo-siRNA in fast muscle tissues, the expression of myogenic regulatory factors (<i>MRFs</i>) <i>and Myomaker</i> was significantly reduced in the <i>Twist2</i>-siRNA-treated group compared with the control group, whereas no significant differences were observed for <i>Pax3</i> and <i>Pax7</i>. Furthermore, the diameter of myofibers and the number of nuclei in single myofibers were reduced, and concurrently, the number of BrdU-positive cells (proliferating cells) was significantly reduced in the <i>Twist2</i>-siRNA-treated group. Taken together, this study demonstrates that Twist2 promotes myoblast proliferation and fusion, thereby regulating fast muscle growth in juvenile Chinese perch. These findings provide a clear direction for further exploration of molecular mechanisms underlying skeletal muscle growth in economic fish species.