Temporal expression of TnI fast and slow isoforms in biceps femoris and masseter muscle during pig growth

Abstract

Biceps femoris (BF) and masseter muscle (MM) are the mixture of slow oxidative and fast-twitch fibres. Compared with MM, BF had the significantly higher expression of myosin heavy chain (MyHC) fast IIx and IIb isoforms (MyHCIIx and MyHCIIb), but lower expression of MyHC slow isoform (MyHCI) and fast IIa isoform (MyHCIIa). The objective of this study was to investigate the expression pattern of troponin I (TnI) slow-twitch isoform (TNNI1) and fast-twitch isoform (TNNI2) in BF and MM of Yorkshire and Meishan pigs which differed significantly in the growth rate. The expression of the TNNI1 and TNNI2 peaked at the postnatal 35 days in Yorkshire pigs and postnatal 60 days in Meishan pigs. The expression of TNNI1 and TNNI2 in Meishan pigs was significantly higher than that in Yorkshire pigs at the foetal 60 days, while the opposite occurred at postnatal 35 days. The expression ratio of TNNI1 relative to TNNI2 favoured TNNI2 expression in BF and MM regardless of Yorkshire and Meishan pigs. TNNI1 expression in MM was significantly higher than that in BF at 60, 120 and 180 days in Meishan pigs and at 120 and 180 days in Yorkshire pigs. On the contrary, no significant difference of TNNI2 expression in BF and MM was found except for Yorkshire pigs of 180 days. This study provided the foundation for future research on TnI isoforms as the model gene to study mechanisms of muscle fibre-specific gene regulation in pigs.

Pleiotropic Genes Affecting Carcass Traits in Bos indicus (Nellore) Cattle Are Modulators of Growth

“…Besides PLAG1 , we found a series of growth-related genes, including growth differentiation factors 2 ( GDF2 ) [ 41 ], 10 ( GDF10 ) [ 42 ] and 11 ( GDF11 ) [ 43 ], growth arrest-specific 2 like 3 ( GAS2L3 ) [ 44 ], fibroblast growth factor 22 ( FGF22 ) [ 45 ], PH domain and leucine rich repeat protein phosphatase 1 ( PHLPP1 ) [ 46 ], signal transducer and activator of transcription 2 ( STAT2 ) [ 47 ], SMAD family member 4 ( SMAD4 ) [ 48 ], and insulin-like growth factor binding protein 5 ( IGFBP5 ) [ 49 ]. Genes involved in muscle development and function were also found, including methylmalonyl CoA mutase ( MUT ) [ 50 ], troponin T type 1 ( TNNT1 ) [ 51 ], troponin I type 3 ( TNNI3 ) [ 52 ], and sarcoglycan delta ( SGCD , also known as 35kDa dystrophin-associated glycoprotein) [ 53 ].…”

Changes in muscle fiber type and expression of mRNA of myosin heavy chain isoforms in porcine muscle during pre‐ and postnatal development

“…Quantification of mRNA was performed with a Roche Diagnostic apparatus, LightCycler ST300, using a commercial kit (QuantiTect SYBR Green PCR kit; Qiagen K.K., Tokyo, Japan). As for the primers for MHC isoforms, we referred to the ones published by Xu et al (). The porcine 18S ribosomal RNA (18S) was used as an internal standard and the primers were designed based on the sequence of porcine 18S (AY265350).…”

“…This description remains a qualitative one and they did not mention anything about quantitative aspects. Quantitative data on postnatal development of the types of muscle fiber were reported by Xu et al (2010) and Men et al (2013). However, neither data on the fetal stage nor on shortly after farrowing were obtained by those studies.…”

Troponin Variants as Markers of Skeletal Muscle Health and Diseases

“…Troponin I shows significant slow and fast isoform variations during development depending on the species and the muscle group studied. In the biceps femoris of pigs, fast TnI expression was lower in fetus and increased with age while slow TnI expression decreased, corresponding to a decrease in slow MHC I and an increase in fast MHC IIb ( Xu et al, 2010 ). Studies in mice supported this notion and found low but detectable levels of fast TnI in developing embryos which was suppressed over time during postnatal maturation of slow-twitch fibers.…”