Regulation of Cell Apoptosis and Water Retention in Postmortem Qinchuan Beef by B-cell Lymphoma-2

Abstract

In order to investigate the regulatory effect of B-cell lymphoma-2 (Bcl-2) on cell apoptosis and water retention in postmortem Qinchuan beef, the longissimus dorsi muscle of Qinchuan cattle was injected with either 200 μmol/L glycochenodeoxycholic acid (GCDA) or 10 μmol/L 2-ethyl-3-methylpentanamide (ABT-737) solution and aged at 4 ℃ postmortem. After 0, 6, 12, 24, 48, 72 and 120 h, the changes in Bcl-2 and Bcl-2-associated X protein (Bax) contents, the concentrations of endoplasmic reticulum and mitochondrial calcium ion, voltage-dependent anion channel protein 1 (VDAC1) expression, calpain content, the mitochondrial apoptosis pathway and water retention were determined. The results showed that at 6 h after slaughter, the Bcl-2 content of the GCDA-treated group was significantly higher than that of the control group (P < 0.01), the calcium ion concentration in the endoplasmic reticulum was significantly lower than that of the control group (P < 0.01), and cooking loss was significantly lower in both treatment groups than the control group (P < 0.05). At 12 and 24 h post-slaughter, the Bcl-2 content of the ABT-737-treated group was significantly lower than that of the control group (P < 0.01). At 12 and 120 h post-slaughter, the endoplasmic reticulum calcium ion, mitochondrial calcium ion and calpain levels in the ABT-737-treated group were significantly greater than those in the control group (P < 0.01). During 0–120 h post-slaughter, the total expression of VDAC1 in both treatment groups was lower than that in the control group. In summary, during the postmortem aging of Qinchuan beef, under the regulation of Bcl-2, calcium overload occurs through VDAC1-facilitated calcium transport, resulting in the activation of calpain, and the overloading of Ca2+ in mitochondria promotes the activation of caspase-9 and caspase-3, thus inducing cell apoptosis. The higher the degrees of cell apoptosis and caspase activation, the higher the degree of degradation of myofibrillar proteins, and the poorer the water-holding capacity of the meat.

Keywords

• b-cell lymphoma-2; postmortem maturation; longissimus dorsi muscle of qinchuan cattle; apoptosis; ca2+; water retention of meat