| Muscle growth and development are tightly regulated by many factors in time and space, which MSTN/Smad signaling pathway plays an important role in the regulation of mammalian embryonic development and postnatal growth and development of muscles. MSTN primarily through binds its receptor ActR?B and activates Smad2, Smad3 protein, then combining Smad4 enters the nucleus to act on target genes MyoD, thereby inhibits muscle growth and development; FST is the MSTN antagonists, by binding MSTN releases the suppression of muscle growth. In this experiment, using qRT-PCR to detect the the developmental expression of FST, MSTN, ActR?B, Smad2, Smad3, Smad4 gene at the mRNA level in longissimus muscle tissue and detect the developmental expression of FST and Smad2 at the protein level. (The growing point is 1,30,60,90,120,150,180 days after birth).The results are as follows:(1) In two pig breeds, FST, MSTN, ActR?B gene showed different developmental expression patterns at mRNA levels. FST, MSTN gene expression were highest at 90 days old in Yorkshire, while highest expression at 150 days old in Mashen pigs. ActR?B gene expression at 90 days old was significantly higher than the other days in Mashen pigs, while other days showed low expression trend. The highest ActRIIB gene expression was at birth, fllowed by 90 days old in Large White. ActR?B gene expression was higher in Mashen than the Large White except for 1 and 150 days. FST and MSTN, MSTN and ActR?B had a significant correlations in Large White. But had no significant correlations in Mashen.(2) In the two breeds, the FST gene expression changes happened in Mashen after Large White, the expression had the significant differences in the other days besides 30 days. The FST gene expression was significantly higher in Mashen than Larger White in 60 days(P<0.01), While Larger White was significantly higher in others days(P<0.01). This showed that muscle development was earily in Larger White than Mashen, FST maybe play a role in this process.(3) Smad2 and Smad3 gene had the same developmental expression patterns in Mashen and Large White pigs.The patterns were first increase and then decreased. Expression of Smad4 gene in two breeds had no obvious regularity. In Large White Smad4 gene expression at 60 days was significantly higher than other days, and in Mashen overall expression levels was relatively low, the highest expression was at 150 days old. Smad2 and Smad3 had a significant correlation in Large White and Mashen.(4) FST protein expression was highest at birth, that was significantly higher than other days (P<0.01). In Mashen 30 and 60 days old had a high expression levels and no significant difference.But they were significantly higher than other days (P<0.05). Compared to the same age in different breeds, FST protein expression in Mashen was higher than in the large White. However, the FST gene had different developmental expression patterns at mRNA and protein levels.(5) Smad2 gene had the same developmental expression patterns at protein level in Large White and Mashen pigs longissimus muscle, that were reduced after first increase. While Mashen had the highest expression at 30 days old, however, Large White at 90 days old. They all had the lowest expression at 1 day old, that significantly lower than other days(P<0.01). The developmental expression patterns of Smad2 gene were consistent at mRNA and protein levels in Large White. The highest expression was at 30 days old. But the expression peak was different at mRNA and protein levels in Mashen.This experiment studied the developmental expression of MSTN/Smad signaling pathway related genes. The aim of this study to provide theoretical references for further study of its mechanism of action and lay the foundation for breeding pigs in the future. |
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