MyH7 antisense long non-coding RNA promotes the formation of slow-twitch fibers through stabilizing MyH7 mRNA

Long non-coding RNA (lncRNA) can regulate mRNA stability by directly binding to mRNA, exerting a significant regulatory effect on muscle growth and development. Improving pork quality is a key objective in breeding superior pig breeds, where the proportion of slow-twitch fibers is intimately linked to meat quality attributes. In this study, we found that a cross-species conserved MyH7 antisense (AS) lncRNA was significantly more highly expressed in the longissimus thoracis (LT) muscle of the obese-type Bamei pigs, suggesting its potential role in myofiber type switching. Overexpression of MyH7 AS lncRNA in porcine skeletal muscle primary cells and C2C12 myoblasts promoted the formation of slow-twitch myotubes and inhibited the expression of fast myosin heavy chain protein. Mechanistic investigation revealed that MyH7 AS lncRNA enhances the stability of MyH7 mRNA by forming a double-stranded structure with it, thereby facilitating the generation of slow-twitch fibers. Further in vivo experiments demonstrated that intramuscular injection of AAV9-mediated MyH7 AS lncRNA overexpression vectors into mice elevated the proportion of slow-twitch fibers and enhanced exercise endurance. These results provide a theoretical basis for improving pork quality by regulating muscle fiber types.