Conclusion
miR-432 protects against MI/R injury by activating the β-catenin/HIF-1α pathway and augmenting NRF2-mediated anti-oxidative stress.
Methods
We established a MI/R injury model by ligation/untying of the left anterior descending coronary artery, and used viral infection to regulate gene expression, such as that of miR-432 in vitro and in vivo, and used RT-qPCR to detect the expression of the gene at mRNA level. Finally, western blotting and immunochemistry analyses were used to determine the protein level.
Objective
MicroRNAs (miRNAs) have been shown to play an important role in myocardial ischemia/reperfusion (MI/R) injury. This study aimed to determine the role of miR-432 in MI/R injury.
Results
The results of this study show that miR-432 is upregulated in the heart following MI/R injury and that miR-432 overexpression showed a significant decrease, while miR-432 knockdown showed a significant increase in the ratio of the infarct area (IA) to the area at risk (AAR) and levels of serum creating phosphokinase (CPK). Moreover, miR-432 augmented the activation of the β-catenin pathway and decreased the rate of apoptosis in the mice heart at 24 hours after MI/R injury by targeting RBM5. At the same time, miR-432 overexpression enhanced HIF-1α activation, while β-catenin deletion attenuated HIF-1α activation induced by miR-432 overexpression. Importantly, β-catenin and HIF-1α knockdown significantly increased the rate of apoptosis and the ratio of IA to AAR and levels of serum CPK induced by miR-432 overexpression at 24 hours after MI/R injury. miR-432 overexpression strongly decreased levels of SOD and GSH-PX activity, and increased levels of MDA activity and the expression of the gp91phox protein in the mice hearts at 24 hours after MI/R injury, while miR-432 knockdown exerted an opposite effect. miR-432 was also found to have increased NRF2 protein levels by targeting KEAP1 protein expression. NRF2 knockdown reversed the downregulation of the levels of gp91phox protein and MDA, while it also reversed the upregulation of the levels of SOD and GSH-PX induced by miR-432 overexpression in the heart of the mice at 24 hours after MI/R injury.