RESUMO
Oxidative stress and apoptosis are the most important pathologic features of ischemic heart disease. Recent research has indicated that microRNAs (miRs) play an essential role in apoptosis. However, whether miRs might regulate B cell lymphoma-2 (Bcl-2) protein in apoptosis during ischemic heart disease is still unclear. The aim of this study, therefore, was to confirm the regulation of microRNA-135a (miR-135a) in oxidative stress injuries induced by hydrogen peroxide (H2O2) in rat cardiomyoblast cells H9c2. To this end, we analyzed the effects of H2O2 treatment on miR-135a expression in rat cardiomyocytes. Furthermore, we upregulated and inhibited miR-135a using mimics and inhibitors, respectively, and examined the effects on cell viability and apoptosis-related proteins. We observed that miR-135a was markedly up-regulated under H2O2 treatment in rat cardiomyoblast cells. Overexpression of miR-135a blocked the Bcl-2 protein and enhanced the apoptosis induced by H2O2, and miR-135a inhibition restored Bcl-2 protein expression. Interestingly, miR-135a inhibition did not attenuate H2O2-induced apoptosis with Bcl-2 knockdown. The results of the present study indicate that miR-135a regulates H2O2-induced apoptosis in H9c2 cells via targeting Bcl-2, and that miR-135a may be a novel therapeutic target for ischemic heart disease.
Assuntos
Apoptose/efeitos dos fármacos , Peróxido de Hidrogênio/farmacologia , MicroRNAs/metabolismo , Miócitos Cardíacos/efeitos dos fármacos , Miócitos Cardíacos/metabolismo , Animais , Apoptose/genética , Western Blotting , Caspase 3/metabolismo , Linhagem Celular , Proliferação de Células/efeitos dos fármacos , Proliferação de Células/genética , Sobrevivência Celular/efeitos dos fármacos , Sobrevivência Celular/genética , Citometria de Fluxo , MicroRNAs/genética , Estresse Oxidativo/efeitos dos fármacos , Estresse Oxidativo/genética , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , Ratos , Reação em Cadeia da Polimerase em Tempo Real , Proteína X Associada a bcl-2/metabolismoRESUMO
OBJECTIVE: To determine the effect of atorvastatin on rat heart failure after myocardial infarction and to investigate the underlying mechanism of atorvastatin-mediated myocardium protection. METHODS: Thirty-eight rats were randomly divided into three groups: a heart failure model group (model group), a heart failure plus atorvastatin treatment group (atorvastatin group) and a sham-surgery group (control group). The rat heart failure model was established by ligation of the left anterior descending of coronary arteries (LADs). Changes in hemodynamics parameters were recorded after the final drug administration. Plasma brain natriuretic peptide (BNP) concentration was determined by enzyme-linked immunosorbent assay (ELISA). Histological diagnosis was achieved by hematoxylin and eosin (H&E) and Masson's trichrome staining. The expressions of 78 kDa glucose-regulated protein 78 (GRP78), caspase-12 and C/EBP homologous protein (CHOP, also known as GADD153) in myocardial cells and cultured cardiac myocytes were examined by Western blot. Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) was used to evaluate myocardial cell apoptosis, and flow cytometry was performed to examine the cell apoptosis of cultured cardiac myocytes. RESULTS: In the atorvastatin group, myocardial cells were lined up more orderly and myocardial fibrosis level was decreased compared to the model group. The expressions of GRP78, caspase-12 and CHOP in myocardial cells were decreased in atorvastatin group. Moreover, in the atorvastatin-treated group the cell apoptosis rate was reduced and the endoplasmic reticulum (ER) stress was activated in response to heart failure and angiotensin II (Ang II) stimulation. CONCLUSIONS: By down-regulating GRP78, caspase-12 and CHOP expressions in myocardial cells in rat heart failure after myocardial infarction, atorvastatin treatment decreased the apoptosis of myocardial cells, suggesting the possible mechanism by which atorvastatin functions in protecting against heart failure.
