Targeted over-expression of PPARγ in pig skeletal muscle improves oxidative fiber formation and intramuscular fat deposition

Abstract

PPARγ is a master regulator of adipogenesis and lipogenesis. To understand its roles in fat deposition and fiber formation in skeletal muscle, we successfully generated muscle-specific overexpression of PPARγ by pig cloning procedures. The content of intramuscular fat was significantly increased in PPARγ transgenic pigs while the muscle mass as lean percentage of body weight was not changed. The proteomics analysis demonstrated oxidative metabolism of fatty acids and respiratory chain were increased in PPARγ pigs. Furthermore, expressions of oxidative muscle fiber-related genes such as MyHC1 and TNNT1 were enhanced. CAMK2, MEF2 and PGC1α were also significantly increased in skeletal muscle of PPARγ pigs, indicating that Ca2+-sensitive phosphatases and kinases may play an important role in the switch of muscle fiber types when PPARγ activity is elevated in skeletal muscle. The results support skeletal muscle-specific overexpression of PPARγ can promote oxidative fiber formation and intramuscular fat deposition in pigs.