WIPI1-mediated mitophagy dysfunction in ventricular remodeling associated with long-term diabetes mellitus

Background: WIPI1 is a member of the WD-repeat protein family that interacts with phosphoinositides and plays a crucial role in autophagy. This study investigated how WIPI1-mediated mitophagy dysfunction contributes to ventricular remodeling in rat and mouse models of diabetes mellitus. Methods: The study utilized a 32-weeks diabetic animal model to simulate long-term diabetic conditions. AAV9-cTNT-WIPI1 vectors were employed to overexpress WIPI1 in the myocardium. Cardiac function was assessed by echocardiography. Mitochondrial membrane potential was assessed using JC-1 dye. Oxygen consumption rates were quantified using an Oxygraph-O2K high-resolution respirometry. Results: Long-term diabetes led to decreased ejection fraction and fractional shortening associated with a marked increase in ventricular fibrosis and elevated expression of fibrotic markers such as collagen type I and periostin. Expression of autophagy markers such as LC3b-II and SQSTM1 was reduced, and colocalization with mitochondria was disrupted, suggesting failures in autophagosome formation and maturation. This impairment was further supported by decreased levels of mitophagy-related proteins (PINK and Parkin), indicating impaired mitophagy. WIPI1 knockdown led to mitochondrial dysfunction, characterized by loss of membrane potential and reduced respiratory capacity. Conclusion: WIPI1 is essential for proper mitophagy function. Its downregulation produces ventricular remodeling and dysfunction. These findings suggest that targeting WIPI1-mediated pathways could be a potential therapeutic strategy for treating diabetic cardiomyopathy by improving mitochondrial health and mitophagic processes.