The Role of AMPK‐SIRT1 Pathway in High Glucose‐Induced Insulin Resistance in Rat Cultured Podocytes

Abstract

Podocytes insulin sensitivity is critical for glomerular function and the loss of correct insulin signaling in consequence leads to alterations and disorders featuring diabetic nephropathy. The energy sensing pathways, like AMP‐dependent protein kinase (AMPK), and class III protein deacetylase SIRT1 have been shown to play an important role in insulin resistance.The aim of this study was determination of the role of AMPK and SIRT1 in insulin resistance of podocytes exposed to high glucose concentration. Experiments were performed in primary rat podocytes cultured with normal (NG, 11.1 mM) or high (HG, 30 mM) glucose concentrations for 5 days. Insulin‐stimulated changes in glucose uptake were used to detect insulin resistance.HG decreased the phosphorylation of AMPK by about 20% (P<0.05) and abolished insulin‐stimulated glucose uptake into podocytes. Knockdown of SIRT1 protein expression in NG‐cultured podocytes decreased AMPK phosphorylation by about 30% and abolished insulin‐stimulated glucose uptake. The stimulating effect of resveratrol (RSV) on AMPK phosphorylation was observed in cells cultured in NG or HG medium, by about 50% and 65%, respectively. Glucose uptake was also increased in HG‐cultured podocytes treated with RSV.We found that impairment of insulin induction of glucose uptake into podocytes cultivated in the presence of high glucose concentrations for long periods of time is associated with decreased AMPK phosphorylation in an SIRT1‐dependent manner. This work was supported by grant from the National Science Centre (Grant 2012/05/N/NZ5/01448).