Knockdown of TUG1 aggravates hypoxia-induced myocardial cell injury via regulation of miR-144-3p/Notch1

Myocardial infarction is a common cause of mortality in cardiovascular diseases. Long noncoding RNA taurine-upregulated gene 1 (TUG1) has been reported to play an important role in the regulation of myocardial injury; however, the mechanism via which TUG1 participates in myocardial infarction is unknown. In this study, hypoxia-treated cardiomyoblast H9c2 cells were used as a model of myocardial infarction. Cell transfection was conducted using Lipofectamine 2000 for 48 h. Hypoxia-induced injury was investigated by cell viability and apoptosis using the trypan blue exclusion method, flow cytometry and Western blot. The expressions of TUG1, microRNA-144-3p (miR-144-3p) and the Notch1 pathway were investigated by a quantitative real-time polymerase chain reaction and Western blot. The association between miR-144-3p and TUG1 or Notch1 was analyzed by bioinformatics analysis and luciferase reporter assay. Our results showed that hypoxia-induced H9c2 cell injury led to the inhibition of cell viability and promotion of apoptosis. Moreover, hypoxia could cause the up-regulation of TUG1 and Notch1 expression and down-regulation of miR-144-3p. The knockdown of TUG1 or overexpression of miR-144-3p aggravated the hypoxia-induced viability suppression and apoptosis production in the H9c2 cells. Moreover, miR-144-3p was indicated to be bound to TUG1, and its abrogation reversed the silencing of TUG1-mediated promotion of hypoxia-induced injury. In addition, Notch1 was a target of miR-144-3p, and its restoration attenuated the miR-144-3p-mediated promotion of hypoxia-induced injury. Moreover, TUG1 interference alleviated the hypoxia-induced activation of the Notch1/Hes-1 pathway via the regulation of miR-144-3p. In conclusion, the interference of TUG1 contributed to hypoxia-induced injury via the regulation of the miR-144-3p/Notch1/Hes-1 pathway; this indicated a novel mechanism for understanding the pathogenesis of myocardial infarction.