In order to uncover the role of the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT) (PI3K/AKT) signaling pathway in metabolic regulation in Tan sheep meat during chilled storage, the transcriptome changes of lamb meat injected with the PI3K inhibitor LY294002 after 0, 4 and 8 days of chilled storage were studied by high-throughput sequencing. Altogether, 474, 96, and 13 differentially expressed genes (DEGs) between the control and LY294002 treatment groups were identified on days 0, 4, and 8, respectively. Functional enrichment analysis showed that the DEGs were mainly related to metabolic homeostasis, such as amino acid biosynthesis, glycolysis/gluconeogenesis, and glyceride metabolism. In addition, tissue section analysis showed that the gap between muscle fibers in the LY294002 group increased and the diameter of muscle fibers decreased significantly relative to the control group, indicating muscle atrophy. These results indicated that the PI3K/AKT signaling pathway played a crucial role in maintaining metabolic balance during the storage of Tan mutton, which in turn ensured the normal growth of muscle. This study provides a new direction for further elucidating the molecular mechanism by which the PI3K/AKT signaling regulates metabolic homeostasis in Tan mutton during chilled storage.

The hindleg meat of Tan sheep was injected postmortem with the phosphoinositide 3-kinase (PI3K) inhibitor LY294002 at a concentration of 10 μmol/L and stored at 4 ℃. After 0, 2, 4, 6 and 8 days, the protein expression of PI3K and protein kinase B (AKT)was analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blot so as to verify whether the PI3K/AKT signaling pathway was effectively inhibited. Meanwhile, we analyzed changes in energy factors, oxidative stress levels, the degree of mitochondrial damage and cysteine aspastic acid-specific protease 3 (caspase-3) activity in order to explore the mechanism by which the PI3K/AKT signaling pathway induces the pathways of cell apoptosis during chilled storage of Tan sheep meat. The results showed that during storage, the protein expression levels of PI3K and AKT showed a decreasing trend, indicating that LY294002 inactivated the PI3K/AKT signaling pathway. Compared with the control group, LY294002 treatment significantly reduced mitochondrial ATP, glycogen content, succinate dehydrogenase (SDH) and citrate synthase (CS) activity (P < 0.05), gradually increased mitochondrial reactive oxygen species (ROS) levels, elevated the levels of oxidative stress and the opening of mitochondrial permeability transition pore (MPTP), significantly decreased membrane potential (P < 0.05), and significantly augmented the activity of caspase-3 (P < 0.05), indicating that the PI3K/AKT signaling pathway mediates the activation of downstream caspase-3 by promoting the production of ROS to interact with PI3K, damaging the structure and function of mitochondria, leading to the opening of MPTP and decreased membrane potential, and ultimately inducing cell apoptosis.