The current study was conducted to evaluate the functions of μ-
calpain (CAPN1),
calpastatin, HSPs (
heat shock proteins), and
caspases during myogenesis and cell death induced by
sodium azide (NaN(3))
hypoxia. The cell samples were divided into three groups: satellite cells formed at confluent monolayer (stage 1), stage 1 cells fusion into myotubes on d eight post-differentiation (stage 2), and stage 2 cells treated with 1 mM NaN(3) for 24 h (stage 3). Real-time RT-PCR showed that stage 2 cells had increased CAPN1,
calpastatin,
caspase 7, and CARD9 (Caspase activation and recruitment domain 9)
mRNA expressions compared to stage 1 cells (*p < 0.05). By Western blotting
caspase 3,
caspase 7,
caspase 8, and
caspase 9 protein levels increased in cells at stage 2 compared to cells at stage 1 (*p < 0.05). Real-time RT-PCR showed that stage 3 cells had increased CAPN1,
calpastatin,
caspase 7, HSP70 (70 kDA
heat shock proteins), and HSP90 (90 kDA
heat shock proteins-alpha) and decreased CARD9
mRNA expression compared to stage 2 cells (*p < 0.05). Stage 3 samples had increase
caspase 7 and
caspase 12 activities compared to stage 2 samples, and by Western blotting
protein levels of both HSP70 and HSP90 expressions, increased significantly under
hypoxia condition (*p < 0.05). Here, we conclude that CAPN1,
calpastatin,
caspase 3,
caspase 7,
caspase 8, and CARD9 have important roles for satellite cell myogenesis; and that
caspase 7, 12, HSP70, and HSP90 are involved in the process of apoptotic cell death under
hypoxia conditions and we speculate that these
proteins may be involved in early postmortem proteolysis and meat tenderization.