Mitigation of Injury from Myocardial Infarction by TH1834, an Inhibitor of the Acetyltransferase Tip60

It is estimated that up to one billion cardiomyocytes (CMs) can be lost during myocardial infarction (MI), which results in contractile dysfunction, adverse ventricular remodeling, and systolic heart failure. Pharmacologic strategies that target factors having both pro-apoptotic and anti-proliferative functions in CMs may be useful for the treatment of ischemic heart disease. One such multifunctional candidate for drug targeting is the acetyltransferase Tip60, which is a member of the MYST family of acetyltransferases known to acetylate both histone and non-histone protein targets that have been shown in cultured cancer cells to promote apoptosis and to initiate the DNA damage response (DDR) thereby limiting cellular expansion. Using a murine model, we recently published findings demonstrating that CM-specific disruption of the Kat5 gene encoding Tip60 markedly protected against the damaging effects of MI. In the experiments described here, in lieu of genetic targeting, we administered TH1834, an experimental drug designed to specifically inhibit the acetyltransferase domain of Tip60. We report that, similar to the effect of disrupting the Kat5 gene, daily systemic administration of TH1834 beginning 3 days after induction of MI and continuing for two weeks of a 4-week timeline resulted in improved systolic function assessed by echocardiography, reduced apoptosis and scarring, reduced expression of markers of the DDR, and increased activation of the CM cell-cycle. Our results support that idea that drugs that inhibit the acetyltransferase activity of Tip60 may be useful agents for the treatment of ischemic heart disease.