Modulation of podocyte autophagy and migration by advanced glycationend products through Wnt/β-catenin signaling pathway

Objective To investigate the effect of activated Wnt/β-catenin signaling pathway induced by advanced glycationend products (AGEs) on podocyte autophagy. Methods Mouse immortalized renal cell lines were divided into bovine serum albumin (BSA) group (100 mg/L BSA), AGEs group (100 mg/L BSA-AGEs) and AGEs + DKK-1 group (100 mg/L BSA-AGEs + 100 mg/L DKK-1). Normal cells without intervention were taken as the control group. Western blotting was used to detect the expression of β-catenin, autophagic membrane protein microtubule-associated protein light chain 3-Ⅱ (LC3-Ⅱ) and autophagic substrate p62. Immunofluorescence was used to observe the autophagy of podocytes. The ELISA was used to determine the nephrin level in the cell supernatant. The wound healing assay was used to measure cell migration rate. The cells were treated with AGEs and AGEs+RAGE neutralizing antibody respectively, and the expression of β-catenin protein was detected by Western blotting. Results The expression of p-β-catenin and p62 in AGEs group was increased (P<0.05), while that of LC3-Ⅱ was decreased (P<0.05) as compared with the control group. The expression of p-β-catenin and p62 protein in AGEs + DKK-1 group was lower than that in AGEs group, and that of LC3-Ⅱ was elevated (P<0.05), but there were no significant differences from the control group (P>0.05). There were no significant differences in these indicators between BSA group and control group (P>0.05). Immunofluorescence assay showed that the LC3 fluorescence intensity in AGEs group was significantly lower than that in control group, and the LC3 fluorescence intensity in AGEs + DKK-1 group was higher than that in AGEs group, and there were no significant differences between AGEs group and control group. The content of nephrin in the supernatant of AGEs group was significantly lower than that of the control group (P<0.05), and that in AGEs+DKK-1 group was significantly higher than in AGEs group (P<0.05), but still lower than in control group (P<0.05), there was no significant difference between AGEs group and control group (P>0.05). Compared with control group, the AGEs significantly reduced the migration ability of podocytes (P<0.05), but the AGEs+DKK-1 group and BSA group were not significantly different from control group (P>0.05). The level of β-catenin protein in podocytes treated with AGEs+RAGE neutralizing antibody was significantly lower than that in AGEs group (P<0.05). Conclusions AGEs can inhibit podocyte autophagy and migration by activating Wnt signaling pathway through RAGE, which may be one of the mechanisms in podocyte injury of diabetic patients, and play an important regulatory role in the occurrence and progression of diabetic nephropathy.