LncRNA TUG1 competitively binds to miR-340 to accelerate myocardial ischemia-reperfusion injury

The aberrant expression of long noncoding RNA (lncRNA) taurine-upregulated gene 1 (TUG1) has been previously associated with myocardial ischemia-reperfusion injury (MIRI), but the underlying molecular mechanisms remain elusive. The current study aimed to clarify the functional role of TUG1/microRNA (miR)-340/histone deacetylase 4 (HDAC4)/β-catenin/glucose transporter type 1 (GLUT1) axes in MIRI. The database-based analyses performed predicted the downstream factors of lncRNA TUG1. In the MIRI mouse models and hypoxia/reoxygenation (H/R)-induced cardiomyocyte models, the expression of TUG1/miR-340/HDAC4/β-catenin/GLUT1 was manipulated to examine their effects on the infarction area, cardiomyocyte viability and apoptosis employing the Evans blue/TTC double staining, CCK-8 and TUNEL assays. Furthermore, the dual luciferase reporter and RIP assays verified the binding affinity of miR-340 to TUG1 and HDAC4. Subsequently, a negative correlation between miR-340 and TUG1 or HDAC4 expression was identified in myocardial tissues of MIRI mice and H/R-induced cardiomyocyte models, along with a positive correlation between TUG1 and HDAC4. Additionally, it was established that TUG1 bound to miR-340, and miR-340 targeted HDAC4. TUG1 upregulated HDAC4 expression, thereby promoting MIRI in the mouse models. HDAC4 was proven to repress the expression of β-catenin and its target gene GLUT1. Moreover, the in vivo experiments validated that the inhibition of TUG1/miR-340/HDAC4/β-catenin/GLUT1 axes alleviated MIRI in mice. Collectively, the current study uncovered the role of TUG1/miR-340/HDAC4/β-catenin/GLUT1 axes in MIRI mouse models and H/R-induced cardiomyocyte models which may be a potential therapeutic target for MIRI treatment.