Peroxiredoxin â ¢ mitigates mitochondrial H(2)O(2)-mediated damage and supports quality control in cardiomyocytes under hypoxia-reoxygenation stress.

Peroxiredoxin â ¢ (Prxâ ¢) is a mitochondria-localized peroxidase that plays a key role in detoxifying hydrogen peroxide (H(2)O(2)) and preserving organelle homeostasis. While its antioxidant function is well established under physiological conditions, the role of Prxâ ¢ in the context of cardiac hypoxia/reoxygenation (H/R) injury remains incompletely understood. In this study, we investigated the protective function of Prxâ ¢ in cardiomyocytes exposed to H/R stress, a widely used in vitro model to mimic ischemia/reperfusion injury. Using H9c2 cells and primary neonatal rat cardiomyocytes, we found that Prxâ ¢ knockdown significantly increased mitochondrial H(2)O(2) accumulation, leading to excessive mitochondrial fragmentation, impaired mitophagy, and reduced cell survival following H/R. Western blot analysis revealed that mitophagy regulators Parkin and BNIP3 were upregulated under moderate oxidative stress but were markedly suppressed in Prxâ ¢-deficient cells after H/R, indicating that mitophagy activation is sensitive to the degree of oxidative stress. These findings were confirmed in vivo using mt-Keima transgenic mice, which showed significantly reduced mitophagic flux in Prxâ ¢ knockout hearts subjected to ischemia/reperfusion. In addition, Prxâ ¢ loss impaired lysosomal acidification and proteolytic activity, further contributing to defective autophagic flux. Re-expression of Prxâ ¢ restored mitochondrial morphology, mitophagy activity, and lysosome function, highlighting its central role in maintaining mitochondrial quality control (MQC). Collectively, our results demonstrate that Prxâ ¢ mitigates mitochondrial oxidative damage and preserves MQC by coordinating mitochondrial dynamics, mitophagy, and lysosomal integrity. These findings suggest that Prxâ ¢ may serve as a promising therapeutic target for preventing cardiac injury induced by oxidative stress during ischemia/reperfusion.