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.