Effect of Phosphoinositide 3-Kinase/Protein Kinase B Signaling Pathway on Cell Apoptosis during Chilled Storage of Tan Sheep Meat

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.