Longitudinal epitranscriptome profiling reveals the crucial role of N6-methyladenosine methylation in porcine prenatal skeletal muscle development

N6-methyladenosine (m6A) represents the most abundantly occurring mRNA modification and is involved in the regulation of skeletal muscle development. However, the status and function of m6A methylation in prenatal myogenesis remains unclear. In this study, we first demonstrated that knockdown of METTL14, an m6A methyltransferase, inhibited the differentiation and promoted the proliferation of C2C12 myoblast cells. Then, using a refined m6A-specific methylated RNA immunoprecipitation (RIP) with next generation sequencing (MeRIP-seq) method that is optimal for use with samples containing small amounts of RNA, we performed transcriptome-wide m6A profiling for six prenatal skeletal muscle developmental stages spanning two important waves of porcine myogenesis. The results revealed that, along with a continuous decrease in the mRNA expression of the m6A reader protein insulin-like growth factor 2 mRNA-binding protein 1 (IGF2BP1), the m6A methylome underwent highly dynamic changes across different development stages, with most of the affected genes being enriched in pathways related to skeletal muscle development. RNA immunoprecipitation confirmed that IGF2BP1 targets 76 genes involved in pathways associated with muscle development, including the key marker genes MYH2 and MyoG. Moreover, small interfering RNA (siRNA)-mediated knockdown of IGF2BP1 induced phenotypic changes in C2C12 myoblasts similar to those observed with knockdown of METTL14. In conclusion, we clarified the dynamics of m6A methylation and identified key genes involved in the regulatory network of porcine skeletal muscle development.