Maternal dietary protein affects transcriptional regulation of myostatin gene distinctively at weaning and finishing stages in skeletal muscle of Meishan pigs

Myostatin (MSTN) is suggested to mediate the effect of maternal nutrition on offspring phenotype, yet the mechanisms underlying such adaptive gene regulation is elusive. In this study, we determined the effects of maternal dietary protein on transcriptional regulation of MSTN in skeletal muscle of pig offspring. Fourteen Meishan sows were fed either low-protein (LP) or standard-protein (SP) diets throughout gestation and lactation. MSTN expression in the longissimus dorsi muscle was determined both at weaning and finishing stages. Myostatin mRNA abundance was downregulated at weaning, but upregulated at finishing in LP pigs, indicating stage-specific transcriptional regulation. At weaning, CCAAT/enhancer-binding protein beta (C/EBP beta) in muscle nuclear lysate was decreased in LP piglets, associated with diminished binding of C/EBP beta to all the three putative binding sites in MSTN promoter. None of the four histone modification marks investigated showed differences between SP and LP piglets. Among 12 microRNAs predicted to target MSTN, none was expressed differently. At finishing stage, C/EBP beta content remained unchanged, but the binding of C/EBP beta to two of the three putative binding sites increased in LP pigs. Histone H3 acetylation and histone H3 lysine 27 trimethylation on MSTN promoter were increased, while histone H3 lysine 9 monomethylation was decreased in LP pigs. Moreover, expression of ssc-miR-136 and ssc-miR-500 was significantly reduced. These results indicate that maternal dietary protein affects MSTN expression through distinct regulatory mechanisms at different stages. The immediate effect at weaning is mediated by C/EBP beta binding without epigenetic modifications, whereas the long-term effect at finishing stage involves both C/EBP beta binding and epigenetic regulations, including histone modification and microRNA expression.