Histone Deacetylase Inhibition Attenuates Cardiomyocyte Hypoxia-Reoxygenation Injury

摘要

Background: Cardiac reperfusion injury can have devastating consequences.Histone deacetylase (HDAC) inhibitors are potent cytoprotective agents, but their role inthe prevention of cardiac injury remains ill-defined.Objective: We sought to determine the therapeutic potential of HDAC inhibitors in an invitro model of cardiomyocyte hypoxia-reoxygenation (H/R).Method: H9c2 cardiomyocytes were subjected to H/R and treated with various classspecificand pan-HDAC inhibitors in equal concentrations (5μM). Biological activity ofinhibitors was determined, as a proxy for concentration adequacy, by Western blot foracetylated histone H3 and α-tubulin. Cell viability and cytotoxicity were measured bymethyl thiazolyl tetrazolium and lactate dehydrogenase assays, respectively.Mechanistic studies were performed to better define the effects of the most effectiveagent, Tubastatin-A (Tub-A), on the phosphoinositide 3-kinase (PI3K)/mammalian targetof rapamycin (mTOR) pathway effectors, and on the degree of autophagy.Results: All inhibitors acetylated well-known target proteins (histone H3 and α-tubulin),suggesting that concentrations were adequate to induce a biological effect. Improvedcell viability and decreased cell cytotoxicity were noted in cardiomyocytes exposed toTub-A, whereas the cytoprotective effects of other HDAC inhibitors were inconsistent.Pro-survival mediators in the PI3K/mTOR pathway were up-regulated and the degree ofautophagy was significantly attenuated in cells that were treated with Tub-A.Conclusion: HDAC inhibitors improve cell viability in a model of cardiomyocyte H/R,with Class IIb inhibition (Tub-A) demonstrating superior cellular-level potency andeffectiveness. This effect is, at least in part, related to an increased expression of prosurvivalmediators and a decreased degree of autophagy.