Expression patterns of PPAR gamma 2, PGC-1 alpha, and MEF2C and their association with intramuscular fat content and skeletal muscle tenderness of crossbred Simmental bulls

PPAR gamma 2, PGC-1 alpha, and MEF2C play an important role in skeletal muscle development and fat deposition. This study aimed to determine their mRNA expression levels in longissimus dorsi (Ld), semitendinosus (Se), and soleus (Sol) muscles of crossbred Simmental bulls and estimate their association with intramuscular fat (IMF) content and meat shear force (MSF). We measured the muscle fiber (MF) density and area, IMF content, and MSF of 6-, 12-, and 36-mo-old bulls. We found that the expression patterns differed with age: the PPAR gamma 2 expression in the three muscles of 36-mo-old bulls was greater than that in the muscles of 6-and 12-mo-old bulls (P < 0.05). Furthermore, PGC-1 alpha expression in Sol of 36-mo-old and MEF2C expression in Ld of 12-mo-old bulls were higher than those in the respective muscles of 6-and 12-mo-old bulls, and 6- and 36-mo-old bulls, respectively (P < 0.05). The MF area, IMF content, and MSF increased with age (P < 0.05). The PPAR gamma 2 mRNA expression in Ld, Se, and Sol was positively correlated with MF area and IMF content (P < 0.05) and negatively correlated with MF density (P < 0.05). Thus, PPAR gamma 2 might be a candidate marker, which is positively correlated with IMF content and MF area.