Expression patterns and correlation analyses of muscle-specific genes in the process of sheep myoblast differentiation

The purpose of this study was to establish a system for the isolation, culture, and differentiation of sheep myoblasts, and to explore the expression patterns as well as mutual relationships of muscle-specific genes. Sheep fetal myoblasts (SFMs) were isolated by two-step enzymatic digestion, purified by differential adhesion and identified using immunofluorescence techniques. Two percent horse serum was used to induce differentiation in SFMs. Real-time quantitative and Western blot analyses were respectively used to detect the mRNA and protein expressions of muscle-specific genes including MyoD, MyoG, Myf5, Myf6, PAX3, PAX7, myomaker, desmin, MYH1, MYH2, MYH4, MYH7, and MSTN during the differentiation of SFMs. Finally, the correlation between muscle-specific genes was analyzed by the Pearson correlation coefficient method. The results showed that the isolated and purified SFMs could form myotubes after the induction for differentiation. The marker factors including MyoD, MyoG, myomaker, desmin, and MyHC were positively stained in SFMs. The mRNA expressions of MyoD, MyoG, and myomaker increased and then decreased, while Myf5, PAX3, and PAX7 decreased; Myf6, desmin, MYH1, MYH2, MYH4, and MYH7 increased; and MSTN fluctuated up and down during the differentiation of SFMs. The expression patterns of protein were basically consistent with those of mRNA except MSTN. There existed significant or highly significant correlations at mRNA or protein level among some genes. Some transcription factor proteins (MyoD, Myf5, Myf6, PAX3, PAX7) showed significant or highly significant correlations with the mRNA level of some other genes and/or themselves. In conclusion, SFMs with good myogenic differentiation ability were successfully isolated, and the expression patterns and correlations of muscle-specific genes during SFM differentiation were revealed, which laid an important foundation for elucidating the gene regulation mechanism of sheep myogenesis.