Metformin inhibits high glucose‐induced apoptosis of renal podocyte through regulating miR‐34a/SIRT1 axis

Abstract

Abstract Background Previous studies have reported SIRT1 was inversely modulated by miR‐34a, However, mechanism of metformin (MFN)'s renal podocyte protection under high glucose (HG) conditions and the connection between miR‐34a and SIRT1 expression in diabetic nephropathy (DN) remain unclear. Method We aimed to further elucidate the role of miR‐34a in HG‐treated podocytes in DN. A conditionally immortalized human podocyte cell line was cultivated in d‐glucose (30 mM). Results Microarray and RT‐qPCR revealed that miR‐34a was downregulated in HG‐treated podocytes. Additionally, miR‐34a levels increased in MFN‐treated HG‐induced podocytes. CCK‐8 assay, colony formation assay, flow cytometry, and Western blot detection showed that HG treatment reduced cell viability and promoted via HG treatment, and MFN treatment reversed this phenotypic change. MiR‐34a upregulation caused restored cell viability and suppressed cell apoptosis in HG‐treated podocytes, and miR‐34a downregulation led to damaged cell survival and induced apoptosis in MFN‐administered and HG‐treated podocytes. The dual luciferase reporter assay showed that SIRT1 3′‐UTR was a direct miR‐34a target. Further studies demonstrated an elevation in SIRT1 levels in HG‐exposed podocytes, whereas MFN treatment decreased SIRT1 levels. In addition, miR‐34a upregulation led to reduced SIRT1 expression, whereas miR‐34a inhibition increased SIRT1 levels in cells. MFN‐induced miR‐34a suppresses podocyte apoptosis under HG conditions by acting on SIRT1. Conclusion This study proposes a promising approach to interpret the mechanisms of action of the MFN‐miR‐34a axis involved in DN.

Keywords

• DN
• metformin
• miR‐34a
• podocyte
• SIRT1