Quantitative phosphoproteomic-based insights into dephosphorylation-enhanced myofibrillar protein degradation via...

This study aimed to elucidate the mechanism by which dephosphorylation accelerates myofibrillar protein degradation by regulating mitochondrial apoptosis in porcine postmortem muscle. Phosphoproteomic analysis revealed that mitochondrial proteins could be phosphorylated and dephosphorylated by PKA and AP, respectively, and these proteins are mainly involved in apoptotic signaling and cytoskeletal organization. Mitochondrial dysfunction, apoptosis, and myofibrillar degradation significantly increased from 2 h to 72 h postmortem, irrespective of phosphorylation status. Notably, the dephosphorylated group (AP) exhibited lower phosphorylation level but showed greater apoptotic potential and myofibrillar degradation, as evidenced by increased mitochondrial membrane permeability, cytochrome c oxidation, and marked reductions in desmin and troponin-T levels, which decreased by 49.3 % and 64.3 %, respectively-significantly exceeding those in the control and phosphorylated (PKA) groups. These findings suggest that dephosphorylation may enhance mitochondrial apoptotic signaling, which could accelerate postmortem degradation of myofibrillar proteins.