Lysosomal Fe2+contributes to myofibrillar protein degradation through mitochondrial-dysfunction-induced apoptosis

Abstract

To verify the role of lysosomal Fe2+ in mitochondrial-dysfunction-mediated apoptosis and postmortem tenderization of bovine muscles, mitochondrial apoptotic factors, myofibrillar protein degradation, and μ-calpain activity were evaluated in the control group and the iron chelator desferrioxamine (DFO) group. The control group showed 1) increased mitochondrial swelling and lipid peroxidation by 47% and 36% at 72 h, respectively (P < 0.05), significantly higher than the DFO group at 12–24 h and 72–168 h (P < 0.05); 2) significantly increased mitochondrial Ca2+ influx at 12–24 h (P < 0.01); 3) a 15%, 24%, and 30% lower cytochrome c reduction level than the DFO group at 6–24 h (P < 0.01, P < 0.05); 4) a significantly increased caspase-3 expression level at 0–120 h (P < 0.05), where the caspase-3 activity was 30% and 49% higher than that of the DFO group at 12–24 h, respectively (P < 0.01); 5) an increased μ-calpain activity by 56% at 24–168 h (P < 0.05), and 6) 75% (P < 0.01) and 34% (P < 0.05) higher degradation of desmin and troponin-T than the DFO group at 168 h, respectively. In summary, lysosomal Fe2+ facilitates postmortem tenderization by promoting the mitochondrial-dysfunction-induced apoptosis of bovine muscle.