Abstract / Summary
Abstract Myocardial infarction (MI) remains a leading cause of global mortality, yet the upstream molecular switch coordinating mitophagy with cuproptosis in ischemic cardiomyocytes is poorly understood. Here, integrating machine learning and single-cell RNA sequencing of MI datasets, UBE2D3, an E2 ubiquitin-conjugating enzyme, was identified as a hub gene markedly upregulated in MI. In hypoxic H9c2 cardiomyocytes, UBE2D3 physically interacted with and ubiquitinated ULK1, the master initiator of mitophagy, thereby driving pathological mitophagy. Lentiviral silencing of UBE2D3 attenuated PINK1/Parkin-dependent mitophagy, restored autophagic flux, and suppressed apoptosis, while preserving mitochondrial integrity and rescuing the depletion of FDX1, DLAT and lipoylated-DLAT, which were markers of the cuproptosis-effector machinery. Collectively, we identify UBE2D3 as a previously unrecognized E2 ligase that ubiquitinates ULK1, establishing a “mitophagy–cuproptosis” axis in which unrestrained ULK1-mediated mitophagy exhausts mitochondrial mass and erases cuproptosis effectors. Our findings shift the mechanistic focus from E3 ligases to the E2 enzyme, reconcile mitophagy overdrive with cuproptosis-machinery loss, and nominate UBE2D3 as a promising therapeutic target for ischemic heart disease.