Targeted deletion of NF-kappa B p50 diminishes the cardioprotection of histone deacetylase inhibition

Zhang LX, Zhao Y, Cheng G, Guo TL, Chin YE, Liu PY, Zhao TC. Targeted deletion of NF-kappa B p50 diminishes the cardioprotection of histone deacetylase inhibition. Am J Physiol Heart Circ Physiol 298: H2154-H2163, 2010. First published April 9, 2010; doi:10.1152/ajpheart.01015.2009.-We have recently demonstrated that the inhibition of histone deacetylases (HDAC) protects the heart against ischemia-reperfusion (I/R) injury. The mechanism by which HDAC inhibition confers myocardial protection remains unknown. The purpose of this study is to investigate whether the disruption of NF-kappa B p50 would eliminate the protective effects of HDAC inhibition. Wild-type and NF-kappa B p50-deficient mice were treated with trichostatin A (TSA; 0.1 mg/kg ip), a potent inhibitor of HDACs. Twenty-four hours later, the hearts were perfused in Langendorff model and subjected to 30 min of ischemia and 30 min of reperfusion. Inhibition of HDACs by TSA in wild-type mice produced marked improvements in left ventricular end-diastolic pressure, left ventricular rate pressure product, and the reduction of infarct size compared with non-TSA-treated group. TSA-induced cardioprotection in wild-type animals was absent with genetic deletion of NF-kappa B p50 subunit. Notably, Western blot displayed a significant increase in nuclear NF-kappa B p50 and the immunoprecipitation demonstrated a remarkable acetylation of NF-kappa B p50 at lysine residues following HDAC inhibition. EMSA exhibited a subsequent increase in NF-kappa B DNA binding activity. Luciferase assay demonstrated an activation of NF-kappa B by HDAC inhibition. The pretreatment of H9c2 cardiomyoblasts with TSA (50 nmol/l) decreased cell necrosis and increased in cell viability in simulated ischemia. The resistance of H9c2 cardiomyoblasts to simulated ischemia by HDAC inhibition was eliminated by genetic knockdown of NF-kappa B p50 with transfection of NF-kappa B p50 short interfering RNA but not scrambled short interfering RNA. These results suggest that NF-kappa B p50 acetylation and activation play a pivotal role in HDAC inhibition-induced cardioprotection.