Super-Enhancer Drives THBS3 Expression to Regulate the Proliferation and Differentiation of Bovine Muscle Stem Cells.

Skeletal muscle, the primary meat-producing tissue in bovines, is regulated by a complex transcriptional network during development. The role of Thrombospondin 3 (THBS3) and its associated super-enhancer (SE) in this process remains largely unknown. Here, by integrating multi-omics data, we identified THBS3 as a novel core regulator of myogenesis, orchestrated by a cognate super-enhancer (THBS3-SE). Functional assays demonstrated that THBS3 knockdown significantly promoted the proliferation and myogenic differentiation of bovine muscle stem cells (MuSCs) and accelerated their commitment to a fast-twitch fiber fate. Transcriptomic analysis linked THBS3 function to key signaling pathways controlling muscle growth, especially the mechanistic target of rapamycin (mTOR) signaling pathway. Mechanistically, we found that distal enhancers within the THBS3-SE loop to the THBS3 promoter drive its transcription, and CRISPR-based interference of these enhancers recapitulated the pro-myogenic effects of THBS3 knockdown. Collectively, our findings unveiled a THBS3-SE-mediated regulatory axis that critically governed bovine MuSCs' fate. Targeting this axis may offer a novel strategy for improving beef production efficiency.