Integrating phenotypic and ceRNA network analyses reveals potential hypoxia adaptation mechanisms in Tibetan sheep skeletal muscles

This study examines the impact of altitude on skeletal muscle adaptation in Tibetan sheep and the associated molecular mechanisms. A total of fifteen Tibetan sheep were used, with five each at low (L), middle (M), and high (H) altitude. Myofibril diameter, intramuscular fat (IMF) content, and mRNA and lncRNA expression profiles in the biceps femoris were analyzed. Based on this, a competitive endogenous RNA regulatory network in the biceps femoris was constructed. The results indicated that the myofibril diameter in the H group and the IMF content in the L group were significantly greater than those in the other groups (p < 0.05). These phenotypic changes may be associated with a shift towards Type IIx muscle fibers, though direct fiber-type classification requires further validation. Additionally, the expression levels of lncRNAs, such as LOC114116860, LOC132657892, and LOC114117858, were notably up-regulated in the H group. These lncRNAs may alleviate the inhibitory effects on genes such as FOXO1 and TRIM63 by interacting with miR-186-x, miR-4484-z, and oar-miR-23b. These lncRNAs and mRNAs could be involved in biological processes such as muscle fiber type switching and energy metabolism. This research provides valuable insights into the hypoxia adaptation mechanisms of Tibetan sheep and a foundation for exploring the role of lncRNA and mRNA in the regulation of skeletal muscle plasticity under high-altitude conditions.