Mitochondrial Dysfunction in Myoblasts: A TSPO-Dependent Mechanism of Sarcopenia.

Sarcopenia, the age-related loss of muscle mass and function, poses a significant health burden in aging societies. Although mitochondrial dysfunction is a recognized driver, the upstream molecular regulators remain poorly defined. Here, we identify the mitochondrial translocator protein (TSPO) as a novel negative regulator of myogenesis that is consistently upregulated in aged and sarcopenic muscle. Using gain- and loss-of-function approaches in C2C12 myoblasts, we show that TSPO overexpression disrupts mitochondrial homeostasis, impairs proliferation and differentiation, while TSPO knockdown produces opposite effects-establishing TSPO as a critical modulator of myogenic capacity. Mechanistically, TSPO suppresses the Wnt/β-catenin pathway, and this effect is partially mediated by ROS accumulation. Importantly, in vivo AAV9-mediated TSPO knockdown in aged mice not only restores mitochondrial integrity but also significantly improves muscle mass, strength, and exercise performance. Collectively, our findings uncover a TSPO-Wnt/β-catenin axis that links mitochondrial dysfunction to impaired muscle regeneration in aging. Targeting TSPO may offer a dual-action therapeutic strategy to combat sarcopenia by simultaneously enhancing mitochondrial bioenergetics and reactivating pro-myogenic signaling.