MRTF-A alleviates myocardial ischemia reperfusion injury by inhibiting the inflammatory response and inducing autophagy.

Myocardin-related transcription factor A (MRTF-A) has an inhibitory effect on myocardial infarction; however, the mechanism is not clear. This study reveals the mechanism by which MRTF-A regulates autophagy to alleviate myocardial infarct-mediated inflammation, and the effect of silent information regulator 1 (SIRT1) on the myocardial protective effect of MRTF-A was also verified. MRTF-A significantly decreased cardiac damage induced by myocardial ischemia. In addition, MRTF-A decreased NLRP3 inflammasome activity, and significantly increased the expression of autophagy protein in myocardial ischemia tissue. Lipopolysaccharide (LPS) and 3-methyladenine (3-MA) eliminated the protective effects of MRTF-A. Furthermore, simultaneous overexpression of MRTF-A and SIRT1 effectively reduced the injury caused by myocardial ischemia; this was associated with downregulation of inflammatory factor proteins and when upregulation of autophagy-related proteins. Inhibition of SIRT1 activity partially suppressed these MRTF-A-induced cardioprotective effects. SIRT1 has a synergistic effect with MRTF-A to inhibit myocardial ischemia injury through reducing the inflammation response and inducing autophagy.

miR-8485 alleviates the injury of cardiomyocytes through TP53INP1.

MicroRNAs (miRNAs) feature prominently in regulating the progression of chronic heart failure (CHF). This study was performed to investigate the role of miR-8485 in the injury of cardiomyocytes and CHF. It was found that miR-8485 level was markedly reduced in the plasma of CHF patients, compared with the healthy controls. H2 O2 treatment increased tumor necrosis factor-α, interleukin (IL)-6, and IL-1ß levels, inhibited the viability of human adult ventricular cardiomyocyte cell line AC16, and increased the apoptosis, while miR-8485 overexpression reversed these effects. Tumor protein p53 inducible nuclear protein 1 (TP53INP1) was identified as a downstream target of miR-8485, and TP53INP1 overexpression weakened the effects of miR-8485 on cell viability, apoptosis, as well as inflammatory responses. Our data suggest that miR-8485 attenuates the injury of cardiomyocytes by targeting TP53INP1, suggesting it is a protective factor against CHF.

Function and Mechanism of Trimetazidine in Myocardial Infarction-Induced Myocardial Energy Metabolism Disorder Through the SIRT1-AMPK Pathway.

Myocardial energy metabolism (MEM) is an important factor of myocardial injury. Trimetazidine (TMZ) provides protection against myocardial ischemia/reperfusion injury. The current study set out to evaluate the effect and mechanism of TMZ on MEM disorder induced by myocardial infarction (MI). Firstly, a MI mouse model was established by coronary artery ligation, which was then treated with different concentrations of TMZ (5, 10, and 20 mg kg-1 day-1). The results suggested that TMZ reduced the heart/weight ratio in a concentration-dependent manner. TMZ also reduced the levels of Bax and cleaved caspase-3 and promoted Bcl-2 expression. In addition, TMZ augmented adenosine triphosphate (ATP) production and superoxide dismutase (SOD) activity induced by MI and decreased the levels of lipid peroxide (LPO), free fatty acids (FFA), and nitric oxide (NO) in a concentration-dependent manner (all P < 0.05). Furthermore, an H2O2-induced cell injury model was established and treated with different concentrations of TMZ (1, 5, and 10 µM). The results showed that SIRT1 overexpression promoted ATP production and reactive oxygen species (ROS) activity and reduced the levels of LPO, FFA, and NO in H9C2 cardiomyocytes treated with H2O2 and TMZ. Silencing SIRT1 suppressed ATP production and ROS activity and increased the levels of LPO, FFA, and NO (all P < 0.05). TMZ activated the SIRT1-AMPK pathway by increasing SIRT1 expression and AMPK phosphorylation. In conclusion, TMZ inhibited MI-induced myocardial apoptosis and MEM disorder by activating the SIRT1-AMPK pathway.