miR-23a and miR-24-3p microRNAs regulate the development of myoblasts derived from fetal bovine skeletal muscle

Muscle development is an important factor affecting meat production and meat quality. Recently, some studies reported that miRNAs are involved in muscle development. An improved understanding of the molecular mechanisms of bovine muscle development may contribute to the increase of meat productivity. Here, our study employed myogenic differentiation of fetal bovine platelet-derived growth factor receptor alpha negative (PDGFRα-) bovine progenitor cells (bPCs) to mimic muscle development in vitro. According to the results, we concluded that:
1. bta (Bos taurus)-miR-23a regulates PDGFRα- bPCs differentiation by targeting MDFIC
bta-miR-23a was regulated during myogenic differentiation (MD). Overexpression of bta-miR-23a significantly up-regulated the expression of MyHC and MyoG in both mRNA and protein levels. TargetScan software predicted that the MyoD family inhibitor domain containing (MDFIC) gene was a direct target gene of bta-miR-23a, and the dual luciferase reporter systems was used for target gene verification. Overexpression of bta-miR-23a significantly inhibited the expression of MDFIC at protein levels. Myogenic differentiation of PDGFRα- bPCs was promoted by RNA interference of MDFIC. Furthermore, the activating effect of bta-miR-23a on PDGFRα- bPCs differentiation was attenuated by MDFIC overexpression. Interestingly, we found that MDFIC plays a key role in PDGFRα- bPCs myogenic differentiation through regulating the transcription activity of MEF2C. These results suggested that bta-miR-23a promoted the differentiation of PDGFRα- bPCs by inhibiting the expression of MDFIC.
2. bta-miR-24-3p promotes differentiation but inhibits proliferation of PDGFRα- bPCs by targeting ACVR1B
bta-miR-24-3p, is a key miRNA regulator of the MD of PDGFRα- bPCs. We isolated progenitor cells from the bovine fetal longissimus dorsi muscle and purified them with PDGFRα antibodies to remove fibro-adipogenic progenitors. We observed that bta-miR-24-3p expression was elevated during differentiation, and bta-miR-24-3p overexpression led to promoted MD but suppressed proliferation. Moreover, activin receptor type 1B (ACVR1B) was identified as a direct target of bta-miR-24-3p. ACVR1B-silencing exhibited similar phenotypes to bta-miR-24-3p-overexpressing PDGFRα- bPCs.
Thus, these results extended our understanding on the roles of miRNA in fetal muscle development. MicroRNAs may be used as molecular marker of bovine breeding.