Shift from slow- to fast-twitch muscle fibres in skeletal muscle of newborn heterozygous and homozygous myostatin-knockout piglets

• DOI: 10.1071/rd19103
• Publication Date: 2019-05-20T06:52:36Z
• Authors: Mei-Fu Xuan; Zhao-Bo Luo; Jun-Xia Wang; Qing Guo; Sheng-Zhong Han; Song-Shan Jin; Jin-Dan Kang; Xi-Jun Yin
• Keywords: Heterozygote; 0303 health sciences; Swine; Cloning, Organism; Homozygote; Myostatin; Animals, Genetically Modified; Gene Knockout Techniques; 03 medical and health sciences; Muscle Fibers, Slow-Twitch; Animals, Newborn; Cell Transdifferentiation; Muscle Fibers, Fast-Twitch; Animals; Muscle, Skeletal

Myostatin (MSTN) is a member of the transforming growth factor-β superfamily that negatively regulates skeletal muscle development. A lack of MSTN induces muscle hypertrophy and increases formation of fast-twitch (Type II) muscle fibres. This study investigated muscle development in newborn heterozygous (MSTN+/−) and homozygous (MSTN−/−) MSTN-knockout piglets. Detailed morphological and gene and protein expression analyses were performed of the biceps femoris, semitendinosus and diaphragm of MSTN+/−, MSTN−/− and wild-type (WT) piglets. Haematoxylin–eosin staining revealed that the cross-sectional area of muscle fibres was significantly larger in MSTN-knockout than WT piglets. ATPase staining demonstrated that the percentage of Type IIb and IIa muscle fibres was significantly higher in MSTN−/− and MSTN+/− piglets respectively than in WT piglets. Western blotting showed that protein expression of myosin heavy chain-I was reduced in muscles of MSTN-knockout piglets. Quantitative reverse transcription–polymerase chain reaction revealed that, compared with WT piglets, myogenic differentiation factor (MyoD) mRNA expression in muscles was 1.3- to 2-fold higher in MSTN+/− piglets and 1.8- to 3.5-fold higher MSTN−/− piglets (P<0.05 and P<0.01 respectively). However, expression of myocyte enhancer factor 2C (MEF2C) mRNA in muscles was significantly lower in MSTN+/− than WT piglets (P<0.05). MSTN plays an important role in skeletal muscle development and regulates muscle fibre type by modulating the gene expression of MyoD and MEF2C in newborn piglets.