Differentially expressed proteins during fat accumulation in bovine skeletal muscle.

The objective of this study was to identify the proteins involved in bovine intramuscular fat (IMF) development. Global proteins were monitored in bovine skeletal muscle at muscle-developing versus IMF-increasing stages and with higher versus lower IMF scores, respectively. We identified two differentially expressed (two-fold or more) proteins at the IMF-increasing stage, up-regulated heat shock protein beta 1 (HSPB1) and down-regulated ATP synthase D chain (ATP5H), and two down-regulated proteins with higher IMF scores, carbonic anhydrase 2 (CA2) and myosin light chain 3 (MYL3). In vitro, after adipogenic differentiation, the mRNA expression of HSPB1 and ATP5H did not be changed, but that of CA2 and MYL3 decreased significantly (P<0.05). After myogenic differentiation, the mRNA expression of HSPB1 increased significantly (P<0.05), but expression of other genes did not vary. We suggested that CA2 and MYL3, which expressed down during adipogenic differentiation, could be indicative markers for negative regulation of IMF development.