Metabolic Adaptation and Potential Regulatory Mechanisms of Longissimus Dorsi-Derived Skeletal Muscle Satellite Cells from Hu Sheep Under Insulin Induction

The bidirectional differentiation potential of skeletal muscle satellite cells (SMSCs) enables them to differentiate into myofibers or intramuscular adipocytes, which affects meat quality in livestock. However, how insulin regulates ovine SMSC metabolism remains poorly understood. SMSCs were isolated from the longissimus dorsi muscle of 1-day-old Hu sheep, cultured, identified, and induced to differentiate with insulin. After induction, lipid droplet formation and the number of nuclei per cell were assessed, and samples were collected before adipogenic induction (No_AD) and after adipogenic induction (AD) for qPCR and whole-transcriptome sequencing. Immunofluorescence confirmed cells were positive for PAX7 and DESMIN. Bodipy, Oil Red O, and hematoxylin staining revealed lipid droplets and multinucleated cells. Sequencing and qPCR indicated that insulin promoted fatty acid uptake and utilization, inhibited adipogenic differentiation, and promoted myogenic differentiation. Integrated ceRNA analysis suggested that miR-2447-z and MSTRG.8123.1 may coordinate muscle development and lipid metabolism. In conclusion, under insulin induction, ovine SMSCs may undergo metabolic adaptation through the ceRNA network mediated by miR-2447-z and MSTRG.8123.1, exhibiting enhanced myogenesis, suppressed adipogenesis, and lipid droplet accumulation. These findings provide new insights into insulin-regulated SMSC metabolism, suggesting that leveraging the bidirectional differentiation potential of SMSCs to in-fluence muscle characteristics and fat deposition may be a feasible approach for im-proving meat production traits in sheep.