Expression Of Myogenic Regulatory Factor Genes In Skeletal Muscle Satellite Cells From Wuzhumuqin Sheep In Vitro

The family of myogenic regulatory factors (MRFs) is exclusively expressed in the skeletal muscle, contributing to muscle growth and development, which affects carcass traits and meat characteristics. Skeletal muscle satellite cells (SMSCs) are important regulators of developing skeletal muscle, serving as a model for understanding the biology of the skeletal muscle of ruminants. In this study, we evaluated MRF-related genes in SMSCs that were isolated and purified from naturally grazing Wuzhumuqin sheep during different stages of development. SMSCs were separated from the semitendinosus of fetal stage, 0-month-old, and 6-month-old sheep, and then identified using immunohistochemistry and reverse transcription-polymerase chain reaction methods. The survival rates of the cells decreased significantly (P < 0.01) in each generation after cryopreservation. Expression levels of MYF5 and MYOD decreased successively over subsequent generations (P < 0.01) in proliferated SMSCs. In both proliferated and differentiated SMSCs, expression levels of MYF5 and MYOD decreased during sheep development (P < 0.01). Expression levels of MYF6 and MYOG in sheep muscles increased at month-0 (P < 0.05), and then decreased at 6 months (P < 0.05). However, MRF genes showed higher expression in myogenic-differentiated SMSCs than in proliferated SMSCs (P < 0.01) at all the three stages of growth. These data suggest that MYOD and MYF5 were primarily expressed in proliferated SMSCs, whereas MYOG and MYF6 were primarily expressed in myogenic-differentiated SMSCs. Therefore, our results provide evidence that the expression of MRF genes in the SMSCs varies among different generations, developmental stages, and myogenic differentiation in naturally grazing Wuzhumuqin sheep.