Differentiation capacities of skeletal muscle satellite cells in Lantang and Landrace piglets

// Chun-Qi Gao 1, * , Yin-Long Xu 1, 2, * , Cheng-Long Jin 1 , Xiao-Chao Hu 1 , Hai-Chang Li 3 , Guang-Xu Xing 4 , Hui-Chao Yan 1 and Xiu-Qi Wang 1 1 College of Animal Science, South China Agricultural University/Guangdong Provincial Key Laboratory of Animal Nutrition and Regulation/ National Engineering Research Center for Breeding Swine Industry, Guangdong, China 2 Guangzhou United Bio-Technology Feed Co., Ltd, Guangzhou, China 3 Davis Heart & Lung Research Institute, Wexner Medical Center at the Ohio State University, Columbus, OH, USA 4 Key Laboratory of Animal Immunology of the Ministry of Agriculture, Henan Academy of Agricultural Sciences, Zhengzhou, China * These authors have contributed equally to this work Correspondence to: Hui-Chao Yan, email: yanhc@scau.edu.cn Xiu-Qi Wang, email: xqwang@scau.edu.cn Keywords: satellite cells, differentiation capacity, mTOR signaling pathway Received: January 23, 2017     Accepted: April 03, 2017     Published: May 15, 2017 ABSTRACT We isolated and cultured satellite cells (SCs) from the longissimus dorsi muscles of 1-day-old male Landrace and Lantang piglets to compare the SC differentiation capacity in the two breeds. Lantang piglets yielded more ( P < 0.05) SCs per gram of muscle than Landrace piglets (5.2 ± 0.9×10 4 vs. 2.4 ± 0.2×10 4 ). Transcription of the differentiation markers myogenin and myosin heavy chain I (MyHC I) in the longissimus dorsi muscle was higher in Lantang than Landrace piglets ( P < 0.05). Protein levels of myogenin ( P < 0.05), MyHC I ( P < 0.05), and myogenic regulatory factor 4 ( P = 0.07) were higher in Lantang than Landrace piglet SCs after 72 h of differentiation. Creatine kinase activity was higher in Lantang than Landrace piglet SCs after 24, 48, and 72 h of differentiation ( P < 0.05), and there was a greater fusion index in Landrace piglet SCs after 72 h of differentiation. In addition, phosphorylation of Akt, mTOR, S6K1, S6, and 4EBP1 was lower in Lantang than Landrace piglet SCs ( P < 0.05). Thus differentiation was more extensive in Lantang than Landrace piglet SCs, but expression of the mTOR signaling pathway was lower in Lantang piglet SCs, suggesting mTOR signaling may inhibit myogenic differentiation. These findings reveal that mTOR signaling is a factor in myogenesis and imply that mTOR could potentially serve as an activator of myoblast differentiation and muscle regeneration.