Stage-specific requirement for METTL3-dependent m(6)A epitranscriptomic regulation during myogenesis.

The regulatory role of N(6)-methyladenosine (m(6)A) modification in skeletal muscle myogenesis and muscle homeostasis remains poorly characterized, particularly regarding the functional significance of methyltransferase-like 3 (METTL3), the catalytic subunit of the m(6)A methyltransferase complex (MTC), in myogenic regulation. Through systematic investigation of m(6)A epitranscriptomic remodeling during myogenesis, we demonstrate that METTL3-mediated m(6)As orchestrates myoblast fusion processes in both differentiation and regeneration contexts. Notably, we observed marked induction of Mettl3 expression post-injury, accompanied by substantial transcriptomic alterations in myogenesis-related pathways. High-resolution m(6)A mapping revealed distinct dynamic patterns of METTL3-regulated m(6)As during differentiation, exhibiting dichotomous regulation across target transcripts. Mechanistically, we identified myogenic fusion factors Mymx and Mymk as direct targets of METTL3, showing concomitant upregulation of both transcript abundance and m(6)A deposition during myogenesis. This study provides comprehensive multi-omics resources delineating the mechanistic landscape of METTL3-regulated m(6)As in myogenic programming, establishing METTL3 as a critical regulatory node governing myoblast fusion dynamic.