Hyperglycemia-induced SIRT3 inhibition contributes to diabetic cardiomyopathy by impairing Cav-3-mediated mitophagy.

Diabetic cardiomyopathy (DCM) is a major cause of mortality in diabetic patients, with impaired mitophagy contributing its pathogenesis. Sirtuin 3 (SIRT3) and caveolin-3 (Cav-3) are protective proteins involved in mitophagy, although their precise mechanisms remain unclear. This study investigated the interplay between SIRT3, Cav-3, and mitophagy in DCM. We found that the diabetic C57BL/6 mice exhibited impaired cardiac structure and function, accompanied by reduced mitophagy and decreased expression of SIRT3 and Cav-3. Cav-3 KO mice with diabetes showed further worsened cardiac dysfunction and mitophagy impairment without further affecting SIRT3 expression. In cultured H9C2 cardiomyocytes, both SIRT3 siRNA and Cav-3 siRNA exacerbated high glucose (HG)-induced cardiomyocyte damage and reduced mitophagy occurrence. Interestingly, SIRT3 siRNA significantly decreased Cav-3 expression, but vice not. Additionally, Cav-3 overexpression rescued HG-induced cardiomyocyte injury and mitophagy impairment without affecting SIRT3 expression. Collectively, our findings suggest that hyperglycemia-induced SIRT3 suppression contributes to DCM by impairing Cav-3-mediated mitophagy.