LncRNA HOTAIR Functions As a Competing Endogenous RNA to Upregulate SIRT1 by Sponging MiR-34a in Diabetic Cardiomyopathy

The HOX transcript antisense RNA (HOTAIR) long noncoding RNA (lncRNA), a highly abundant and conserved imprinted gene, has been implicated in many essential biological processes and diseases. However, to date, the significance of HOTAIR in diabetic cardiomyopathy (DCM) has never been investigated. The current study was designed to determine whether DCM can be regulated by HOTAIR and to elucidate the related mechanism. In vivo, streptozotocin (STZ) was injected intraperitoneally to induce type 1 diabetes in mice. Cardiomyocyte specific HOTAIR overexpression was achieved using an adeno-associated virus system 12 weeks after STZ injection. In vitro, H9c2 were used to explore the potential molecular mechanism of HOTAIR in the regulation of high-glucose-induced cardiomyocyte injury. Luciferase reporter assay and RNA immunoprecipitation (RIP) were performed to explore the relationship between HOTAIR, microRNA-34a (miR-34a), and Sirtuin 1 (SIRT1). HOTAIR expression was significantly decreased in diabetic mice hearts. Knockdown of HOTAIR in high glucose-induced H9c2 resulted in increased oxidative injury, inflammation, and apoptosis in vitro. Cardiomyocyte-specific overexpression of HOTAIR improved cardiac function, decreased oxidative stress and inflammation, and attenuated myocyte death in mice treated with STZ. Mechanistically, the expression of SIRT1/forkhead box protein O1 was significantly increased in the HOTAIR-overexpressing hearts compared with the control hearts treated with STZ. Moreover, we found HOTAIR functioned as a molecular sponge of miR-34a in H9c2 and SIRT1 was identified as a target of miR-34a. Furthermore, the protective effects of HOTAIR on DCM was abolished in SIRT1 deficiency mice in vivo. HOTAIR protected against DCM via activation of the SIRT1 expression by sponging miR-34a.