title: HDAC4 degradation mediates HDAC inhibition-induced protective effects against hypoxia/reoxygenation injury.
abstract: Histone deacetylases (HDACs) play a crucial role in the regulation of gene expression through remodeling of chromatin structures. However, the molecular mechanisms involved in this event remain unknown. In this study, we sought to examine whether HDAC inhibition-mediated protective effects involved HDAC4 sumoylation, degradation, and the proteasome pathway. Isolated neonatal mouse ventricular myocytes (NMVM) and H9c2 cardiomyoblasts were subjected to 48 h of hypoxia (H) (1% O2 ) and 2 h of reoxygenation (R). Treatment of cardiomyocytes with trichostatin A (TSA) attenuated H/R-elicited injury, as indicated by a reduction of lactate dehydrogenase (LDH) leakage, an increase in cell viability, and decrease in apoptotic positive cardiomyocytes. MG132, a potent proteasome pathway inhibitor, abrogated TSA-induced protective effects, which was associated with the accumulation of ubiquitinated HDAC4. NMVM transduced with adenoviral HDAC4 led to an exaggeration of H/R-induced injury. TSA treatment resulted in a decrease in HDAC4 in cardiomyocytes infected with adenoviral HDAC4, and HDAC4-induced injury was attenuated by TSA. HDAC inhibition resulted in a significant reduction in reactive oxygen species (ROS) in cardiomyoblasts exposed to H/R, which was attenuated by blockade of the proteasome pathway. Cardiomyoblasts carrying wild type and sumoylation mutation (K559R) were established to examine effects of HDAC4 sumoylation and ubiquitination on H/R injury. Disruption of HDAC4 sumoylation brought about HDAC4 accumulation and impairment of HDAC4 ubiquitination in association with enhanced susceptibility of cardiomyoblasts to H/R. Taken together, these results demonstrated that HDAC inhibition stimulates proteasome dependent degradation of HDAC4, which is associated with HDAC4 sumoylation to induce these protective effects.
authors.affiliation: Department of Surgery, Boston University Medical School, Boston University, Roger Williams Medical Center, Providence, Rhode Island.
authors.forename: Jianfeng
authors.initials: J
authors.lastname: Du
authors.forename: Ling
authors.initials: L
authors.lastname: Zhang
authors.forename: Shougang
authors.initials: S
authors.lastname: Zhuang
authors.forename: Gang Jian
authors.initials: GJ
authors.lastname: Qin
authors.forename: Ting Cun
authors.initials: TC
authors.lastname: Zhao
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D056572:Histone Deacetylase Inhibitors / Q000494:pharmacology*; D006655:Histone Deacetylases / Q000378:metabolism*; D006877:Hydroxamic Acids / Q000494:pharmacology; D000860:Hypoxia / Q000188:drug therapy / Q000378:metabolism; D051379:Mice; D009203:Myocardial Infarction / Q000378:metabolism; D015428:Myocardial Reperfusion Injury / Q000188:drug therapy*; D032383:Myocytes, Cardiac / Q000187:drug effects*; D059748:Proteolysis; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D056572:Histone Deacetylase Inhibitors; D006877:Hydroxamic Acids; D017382:Reactive Oxygen Species; C012589:trichostatin A; C498618:Hdac5 protein, mouse; D006655:Histone Deacetylases