RNF10 deficiency in cardiomyocytes impairs mitophagy and drives pathological hypertrophy.

Mitophagy-mediated mitochondrial quality control is essential for normal cardiac physiology. In this study, we observed that cardiac RNF10 expression was induced by multiple chronic stressors, including aging, angiotensin II (Ang II) exposure, and obesity. Cardiac-specific RNF10 knockout (RNF10-CKO) mice developed cardiac hypertrophy with aging, characterized by cardiomyocyte enlargement, exacerbated myocardial fibrosis, and impaired cardiac function. Aged RNF10-CKO mice exhibited elevated reactive oxygen species (ROS) levels and reduced mitochondrial membrane potential in cardiomyocytes. Transmission electron microscopy revealed mitochondrial rounding, matrix expansion, and cristae disorganization. Similarly, compared with control mice, Ang II-exposed RNF10-CKO mice exhibited cardiomyocyte hypertrophy, increased fibrosis, and cardiac dysfunction, accompanied by mitochondrial membrane potential depolarization, ROS accumulation, and mitochondrial morphological abnormalities equivalent to those in aged RNF10-CKO mice. Mechanistically, chronic stressors upregulated RNF10 expression, which subsequently mediated the K63-linked polyubiquitination of the mitochondrial outer membrane protein mitofusin 2 (MFN2). This modification stabilized MFN2 on mitochondria and facilitated Parkin recruitment. The accumulated Parkin in mitochondria further promoted the robust recruitment of the autophagy adaptor sequestosome 1 (SQSTM1/p62), leading to increased LC3-II lipidation and the initiation of mitophagy. Notably, this RNF10-mediated mitophagy is dependent on MFN2. However, the effects of RNF10 are independent of those of PINK1. This study identifies RNF10 as a critical regulator of cardiac mitophagy, suggesting that targeting cardiac RNF10 may represent a therapeutic strategy for treating cardiac pathologies.