SNHG5 Upregulated by Dexmedetomidine Alleviates Myocardial Ischemia/Reperfusion Injury Through LIN28A-Mediated BCAT1 mRNA Stabilization and Autophagy Enhancement.

SNHG5 serves as a key factor in regulating various cancers, and Dexmedetomidine (Dex) protects against myocardial ischemia/reperfusion (I/R) injury. However, the role of SNHG5 in Dex-mediated protection during myocardial I/R remains uninvestigated. In this study, models of rat myocardial I/R injury and hypoxia/reoxygenation (H/R)-induced cardiomyocyte injury were generated. The infarct size, histological changes and apoptosis in heart tissues were evaluated by TTC, HE, and TUNEL staining. CCK-8, flow cytometry and immunofluorescence were employed to assess cell viability, apoptosis and autophagosome-lysosome fusion in H9c2 cells. The associations among SNHG5, LIN28A and BCAT1 mRNA were detected by RNA pull-down, RIP, and RNA fluorescence in situ hybridization (FISH) assays. Western Blot, qRT-PCR and immunohistochemistry were employed to detect the expression of key molecules. Our results revealed that Dex ameliorated myocardial I/R injury and H/R-induced impairments in H9c2 cells by enhancing autophagy. Moreover, Dex led to a rebound of SNHG5 in the heart tissues of I/R rats and H/R-treated H9c2 cells, and functional studies revealed that Dex protected against cardiac impairments through SNHG5-dependent autophagy in vitro and in vivo. Furthermore, SNHG5 alleviated H/R-induced impairments by recruiting LIN28A protein, which was subsequently bound to BCAT1 mRNA and maintained its stability. In conclusion, our findings demonstrated that SNHG5, when upregulated by Dex, alleviated myocardial I/R injury through LIN28A-mediated BCAT1 mRNA stabilization and autophagy enhancement.