Mitochondrial damage induced by glucolipotoxicity leads to cardiac dysfunction, known as cardiomyopathy. Timely clearance of damaged mitochondria is crucial for maintaining normal cardiac function. Mitophagy is the major mechanism underlying this process. AC16 cells were cultured under high glucose/palmitate (HG/PA) conditions to mimic diabetic cardiomyopathy (DCM). Tumor necrosis factor receptor-associated protein 1 (TRAP1) overexpression and KAT8 regulatory NSL complex subunit 3 (KANSL3) knockdown were achieved via lentiviral transduction. Cell viability was assessed using a Cell Counting Kit-8 (CCK8) assay. Mitochondrial morphology was observed using transmission electron microscopy and Mito-Tracker staining. Mitophagic flux was assessed using autophagy and mitophagy markers, mKeima fluorescence, and immunofluorescence colocalization. Mitochondrial function was assessed by measuring ATP content, the mitochondrial membrane potential (MMP), and mitochondrial oxidative stress. The animal studies used Sprague‒Dawley rats with streptozotocin (STZ)-induced diabetes and a high-fat diet to model DCM. Histological analyses, including H&E, Sirius Red, periodic acid–Schiff (PAS), and Masson staining, were conducted on heart tissue sections. Using immunoprecipitation (IP) and liquid chromatography–tandem mass spectrometry (LC‒MS/MS), we demonstrated that TRAP1 interacts with KANSL3 and that HG/PA conditions influence the acetylation status of KANSL3. Our study revealed that damaged mitochondria accumulation is a significant feature of cardiomyocytes under diabetic conditions, but no activated mitophagy was observed. Further joint analysis revealed that a mitophagy-related protein TRAP1 is significantly downregulated both in in vivo and in vitro models of DCM. Importantly, exogenous expression of TRAP1 restored mitophagy activity and alleviated mitochondrial dysfunction, highlighting the protective role of TRAP1 in cardiomyocytes under diabetic conditions. Mechanistically, TRAP1 was identified as a molecular chaperone that directly interacts with KANSL3, and this interaction was significantly decreased under diabetic conditions. We observed that the acetylation of KANSL3 is crucial for mitophagy dysfunction under diabetic conditions. TRAP1 inhibited KANSL3 acetylation to preserve mitophagy in cardiomyocytes under normal conditions, and downregulation of TRAP1 under diabetic conditions impaired mitophagy and mitochondrial dysfunction. Collectively, these results demonstrate that TRAP1 inhibits KANSL3 acetylation to mediate mitophagy and alleviate mitochondrial dysfunction in cardiomyocytes under diabetic conditions. Our findings provide a potential therapeutic target for DCM.
Zhang et al. (Thu,) studied this question.