MOTS‑c is a tiny protein made by mitochondria that helps cells fix damaged outer membranes by teaming up with a repair protein called TRIM72. Moderate‑intensity exercise raises your body’s MOTS‑c levels, improves membrane repair, and protects heart tissue after injury. In lab tests, MOTS‑c moves TRIM72 to the wound site and also works with membrane lipids to fuse repair vesicles, but it doesn’t fix membranes on its own without TRIM72.

<b>Rationale:</b> An impairment of plasma membrane repair has been implicated in various diseases such as muscular dystrophy and ischemia/reperfusion injury. MOTS-c, a short peptide encoded by mitochondria, has been shown to pass through the plasma membrane into the bloodstream. This study determined whether this biological behavior was involved in membrane repair and its underlying mechanism. <b>Methods and Results:</b> In human participants, the level of MOTS-c was positively correlated with the abundance of mitochondria, and the membrane repair molecule TRIM72. In contrast to high-intensity eccentric exercise, moderate-intensity exercise improved sarcolemma integrity and physical performance, accompanied by an increase of mitochondria beneath the damaged sarcolemma and secretion of MOTS-c. Furthermore, moderate-intensity exercise increased the interaction between MOTS-c and TRIM72, and MOTS-c facilitated the trafficking of TRIM72 to the sarcolemma. <i>In vitro</i> studies demonstrated that MOTS-c attenuated membrane damage induced by hypotonic solution, which could be blocked by siRNA-TRIM72, but not AMPK inhibitor. Co-immunoprecipitation study showed that MOTS-c interacted with TRIM72 C-terminus, but not N-terminus. The dynamic membrane repair assay revealed that MOTS-c boosted the trafficking of TRIM72 to the injured membrane. However, MOTS-c itself had negligible effects on membrane repair, which was recapitulated in TRIM72^-/- mice. Unexpectedly, MOTS-c still increased the fusion of vesicles with the membrane in TRIM72^-/- mice, and dot blot analysis revealed an interaction between MOTS-c and phosphatidylinositol (4,5) bisphosphate [PtdIns (4,5) P₂]. Finally, MOTS-c blunted ischemia/reperfusion-induced membrane disruption, and preserved heart function. <b>Conclusions:</b> MOTS-c/TRIM72-mediated membrane integrity improvement participates in mitochondria-triggered membrane repair. An interaction between MOTS-c and plasma lipid contributes to the fusion of vesicles with membrane. Our data provide a novel therapeutic strategy for rescuing organ function by facilitating membrane repair with MOTS-c.