Long noncoding RNA Glis2 regulates podocyte apoptosis by mediating mitochondrial function in diabetic nephropathy

Abstract Objectives Diabetic nephropathy (DN) is one of the most serious microvascular complications of diabetes and the main cause of end-stage kidney disease. Podocyte injury or apoptosis exerts a crucial role in the pathogenesis of DN. Recently, long noncoding RNAs (lncRNAs) have been gradually identified to be functional in a variety of different mechanisms associating with DN. However, the relationship between lncRNAs and podocyte apoptosis in DN is still in its infancy. This study aimed to investigate whether lncRNA Glis2 could regulate podocyte injury via miR-328-5p in DN and uncover the underlying mechanism. Methods Normal-glucose or high-glucose cultured podocytes and diabetic db/db mice were used to investigate the exact role and regulatory mechanism of lncRNA Glis2 on podocyte apoptosis in DN. Apoptosis rate of podocyte was detected by flow cytometry. Cell viability was measured using the Cell Counting Kit-8 colorimetric assay (CCK-8). The expressions of lncRNA Glis2 and miR-328-5p were measured by qRT-PCR. The relationship between lncRNA Glis2 and miR-328-5p was examined by dual luciferase reporter assay. Mitochondrial membrane potential (ΔΨM) was measured using JC-1 staining. Mitochondrial morphology was detected by MitoTracker Deep Red staining. Then, the histopathological and ultrastructure changes of renal tissues in diabetic mice were observed using periodic acid-Schiff (PAS) staining and transmission electron microscopy. Finally, the effect of lncRNA Glis2 on podocyte mitochondrial dysfunction and apoptosis through miR-328-5p/Sirt1 was detected by western blot. Results We found that lncRNA Glis2 was significantly downregulated in high-glucose cultured podocytes and renal tissues of db/db mice. Furthermore, lncRNA Glis2 overexpression or knockdown was found to regulate podocyte mitochondrial dysfunction and apoptosis. The direct interaction between lncRNA Glis2 and miR-328-5p was confirmed by dual luciferase reporter assay. LncRNA Glis2 overexpression alleviated podocyte mitochondrial dysfunction and apoptosis via miR-328-5p/Sirt1 pathway in podocytes and diabetic mice. Conclusion Taken together, this study demonstrated that lncRNA Glis2, acting as a competing endogenous RNA (ceRNA) of miRNA-328-5p, regulated Sirt1 mediated mitochondrial dysfunction and podocyte apoptosis in DN.