Abstract Body: Myocardial infarction (MI) leads to cardiomyocyte (CM) loss, resulting in cardiac dysfunction and heart failure. Remuscularization of injured myocardium requires proliferation of surviving CMs. However, approaches aimed at inducing CM regeneration following MI have been inadequate. To this end, we are targeting the acetyltransferase Tip60 (Tat-interactive protein 60 kD), a pleiotropic tumor suppressor encoded by the Kat5 gene. Using a murine genetic model, we previously reported that disruption of Kat5 promotes CM cell-cycle re-entry, and protects against the damaging effects of MI. It is becoming increasingly recognized that pre-existing CMs must undergo dedifferentiation accompanied by reversion to glycolytic metabolism in order to resume proliferation. The site-specific acetylation of the histone variant H2A.Z at lysine K4/K7 (H2A.Zac^K4/K7) has been shown to maintain the differentiated state in hematopoietic stem cells (HSCs), neurons, and skeletal myocytes. Here, we report that Tip60 depletion post-MI results in the near-complete absence of H2A.Zac^K4/K7 in CMs. This is associated with the enrichment of differentially expressed genes (DEGs) in epithelial to mesenchymal transitioning (EMT), cytoskeletal disassembly, extracellular matrix (ECM) softening, and metabolic reprogramming. To assess therapeutic relevance, we have begun to evaluate the potential cardioprotective effects of the anti-parasitic drug pentamidine, a known Tip60 inhibitor. Systemic administration of pentamidine on days 3-16 post-MI preserved cardiac function, accompanied by CM cell-cycle activation. These data suggest that pentamidine treatment enhances remuscularization, thereby promoting the retention of post-MI function, supporting the translational promise of targeting Tip60 as an innovative therapy for ischemic heart disease.