Inhibition of Taurine-upregulated Gene 1 Upregulates MiR-34a-5p to Protect against Myocardial Ischemia/Reperfusion via Autophagy Regulation

Background: Taurine upregulated gene 1 (TUG1) has been identified on long noncoding RNA (lncRNA); however, its function in myocardial cells following ischemia/ reperfusion (I/R) injury has not been explored. This study aimed to investigate the role of LncTUG1 in I/R injury by focusing on its relationship with autophagy induction by regulating miR-34a-5p expression. Methods: We established a myocardial I/R model and H9C2 hypoxia-ischemic and reoxygenation (HI/R) conditions to induce I/R injury. TTC, Western blot, CCK-8 assay, quantitative reverse transcription PCR, flow cytometry, and confocal microscopy were used to assess the size of myocardial infarct, level of some apoptotic-related and autophagy-associated proteins, cell viability, the level of LncRNA TUG1, apoptosis, and autophagy, respectively. Results: The results revealed that a TUG1 knockdown protected against I/R-induced myocardial injury by decreasing the impairment in cardiac function. LncRNA TUG1 expression was increased in a myocardial I/R model and HI/R in H9C2 cells. Moreover, inhibition of LncTUG1 enhanced H9C2 cell viability and protected the cells from HI/R-induced apoptosis. Silencing LncRNA TUG1 promoted HI/R-induced autophagy. Furthermore, TUG1 siRNA upregulated the level of miR-34a-5p compared to the HI/R group. The protective effect of LncRNA TUG1 inhibition on H9C2 cells following HI/R was eliminated by blocking autophagy with an miR-34a-5p inhibitor. Conclusion: These findings indicated that inhibiting TUG1 may reduce the extent of myocardial I/R injury by regulating miR-34a-5p. Taken together, these results suggest that LncRNA TUG1 may represent a novel therapeutic target for myocardial I/R injury.