MUSTN1 prevents muscle atrophy through ferroptosis suppression: A ACO1-dependent and exosome-mediated mechanism.

Muscle skeletal embryonic nuclear protein 1 (MUSTN1) is a microprotein expressed and secreted by skeletal muscle satellite cells (SMSCs) and has long been implicated in muscle regeneration, yet its molecular mechanism remains unclear. This study demonstrates that MUSTN1 is transcriptionally regulated by MyoD1 and exerts its regenerative effects by inhibiting ferroptosis. Transcriptome analysis revealed that the overexpression of MUSTN1 leads to the enrichment of genes associated with ferroptosis. Mechanistically, MUSTN1 directly binds to ACO1 (IRP1), enhancing its interaction with the TFRC 3' untranslated region (UTR) of TFRC, thereby promoting TFRC expression and inhibiting SLC39A14, which ultimately alleviates iron accumulation and lipid peroxidation. Functional experiments confirmed that MUSTN1 mitigates dexamethasone-induced atrophy by enhancing myotube area, proliferation, and mitochondrial membrane potential. Additionally, MUSTN1 is secreted via exosomes, and treatment with exosomes containing MUSTN1 significantly promotes in vitro cell proliferation and differentiation while regulating cellular ferroptosis. In summary, our study reveals MUSTN1 as a MyoD1-driven, exosome-transmissible regulatory factor that inhibits ferroptosis by activating the ACO1-TFRC axis, providing mechanistic insights into muscle regeneration and potential therapeutic strategies for muscle atrophy-related diseases.