Anti-apoptotic potency of TNFR:Fc gene in ischemia/ reperfusion-induced myocardial cell injury

Long Non-coding RNA N1LR Protects Against Myocardial Ischemic/Reperfusion Injury Through Regulating the TGF-β Signaling Pathway

Long non-coding RNAs (lncRNAs) have been shown to play critical roles in various cell biological processes. However, the mechanism of lncRNAs in acute myocardial infarction (AMI) is not fully understood. Previous studies showed that lncRNA N1LR was down-regulated in ischemic cerebral stroke and its up-regulation was protective. The current study was designed to assess the protective effect of N1LR and further to explore potential mechanisms of N1LR in ischemic/reperfusion (I/R) injury after AMI. Male C57BL/6J mice and H9c2 cardiomyocytes were selected to construct in vivo and in vitro pathological models. In H9c2 cell line, N1LR expression was markedly decreased after H₂O₂ and CoCl₂ treatments and N1LR overexpression alleviated apoptosis, inflammation reaction, and LDH release in cardiomyocytes treated with H₂O₂ and CoCl₂. Mouse in vivo study showed that overexpression of N1LR enhanced cardiac function and suppressed inflammatory response and fibrosis. Mechanistically, we found that the expression of transforming growth factor (TGF)-β1 and smads were significantly decreased in the N1LR overexpression group exposed to H₂O₂. In a summary, our study indicated that N1LR can act as a protective factor against cardiac ischemic-reperfusion injury through regulating the TGF-β/Smads signaling pathway.

Trichostatin A attenuates oxidative stress-mediated myocardial injury through the FoxO3a signaling pathway

Trichostatin A (TSA), a histone deacetylase inhibitor, is widely used as an anticancer drug. Recently, TSA has been shown to exert a protective effect on ischemia/reperfusion (I/R) injury; however, the underlying mechanisms remain unclear. Forkhead box O3a (FoxO3a), a unique FoxO family member, has been shown to attenuate myocardial injury by increasing resistance to oxidative stress in mice. The present study aimed to investigate whether TSA exerts its cardioprotective effects through the FoxO3a signaling pathway. For this purpose, healthy male Wistar rats were pre-treated with TSA for 5 days before they were subjected to ligation/relaxation of the left anterior descending branch of the coronary artery and to 30 min of ischemia, followed by 24 h of reperfusion. The activities of creatine kinase (CK), lactate dehydrogenase (LDH), aspartate aminotransferase (AST) and superoxide diamutase (SOD), as well as the malondialdehyde (MDA) levels were examined. The H9c2 rat myocardial cell line was cultured in 10% FBS-containing DMEM for 24 h. The cells were incubated with/without TSA (50 nmol/l) for 1 h and then incubated with/without H₂O₂ (400 µM) for 2 h. Reactive oxygen species (ROS) and mitochondrial membrane potential (Δψm) were measured by probe staining in the H9c2 cells. The expression of FoxO3a, mitochondrial SOD2 and catalase was quantified by western blot analysis. The levels of H3 and H4 acetylation of the FoxO3a promoter region were examined by chromatin immunoprecipitation assay. TSA significantly reduced the myocardial infarct size and the activities of serum LDH, AST and CK in the rats. TSA also decreased the levels of MDA and increased the activities of SOD in the myocardial tissue of the rats. Consistent with the reduced injury to the TSA-treated rats, TSA significantly reduced the H₂O₂-induced levels of ROS and increased Δψm. In addition, TSA increased the expression of FoxO3a, SOD2 and catalase, which may be related to increasing the level of H4 acetylation of the FoxO3a promoter region. Our results thus revealed that TSA protected the myocardium from oxidative stress-mediated damage by increasing H4 acetylation of the FoxO3a promoter region, and the expression of FoxO3a, SOD2 and catalase.