Role of GSK-3β/β-catenin signaling pathway in human renal proximal tubular epithelial cell injury induced by depleted uranium / 中华放射医学与防护杂志

ABSTRACT

Objective To investigate the effects of glycogen synthase kinase-3β (GSK-3β) and β-catenin signaling on the human renal proximal tubular epithelial HK-2 cell injury induced by depleted uranium(DU),and provide a new enlightenment for the development of DU antidotes.Methods H K-2 cells were exposed to different concentrations of DU for 3-24 h,then the protein expressions of kidney injury molecule 1 (KIM-1),neutrophil gelatinase-associated lipocalin (NGAL) and nuclear β-catenin were detected by immunofluorescence staining.The protein expressions of p-GSK-3 β(S9),GSK-3β and cmyc were detected by Western blot assay.HK-2 cells were transiently transfected by GSK-3β (KD) plasmid or treated by TDZD-8 to inhibit the activity of GSK-3β specifically.Other HK-2 cells were transiently transfected by β-catenin plasmid to overexpress the β-catenin protein.Results The percentages of KIM-1 and NGAL-positive cells increased with DU exposure time and concentrations from 300 and 600 μmol/L,and they were significantly higher than those of the blank control at 6-24 h of DU exposure (KIM-1-positive cellst =11.06,18.97,30.49,P ＜0.05;t =6.79,16.02,85.45,P ＜ 0.05;NGAL-positive cellst =11.78,11.37,34.29,P ＜0.05;t =7.34,21.63,36.84,P ＜0.05).In contrast,the ratio of p-GSK-3β (S9) to GSK-3β and percentage of nuclear β-catenin-positive cells were significantly higher than that of the blank control at 3-24 h of DU exposure (p-GSK-3β(S9)/GSK-3βt =3.95,4.69,5.40,3.34,P ＜ 0.05;nuclear β-catenin-positive cellst =4.61,6.52,36.64,14.93,P ＜ 0.05) with a maximum response at 9 h of DU exposure accompanied with corresponding increase of protein level of c-myc,a downstream target gene of β-catenin.Transient transfection of HK-2 cells with GSK-3β (KD) plasmid significantly inhibited the activity of GSK-3β (t =8.07,P ＜ 0.05) and reduced the DU-increased percentage of KIM-1-positive cells (t =24.77,P ＜ 0.05).Treatment cells with TDZD-8 inhibited the activity of GSK-3β and enhanced the percentage of nuclear β-catenin-positive cells,and it also significantly reduced the percentage of KIM-1-positive cells in HK-2 cells exposed to DU (t =6.25,6.73,P ＜ 0.05).Moreover,overexpression of β-catenin significantly reduced DU-induced cell injury (t =7.48,P ＜ 0.05).Conclusions GSK-3β/β-catenin signaling plays a key role in regulating the DU-induced cytotoxicity of HK-2 cells.Inhibition of GSK-3β activity and overexpression of β-catenin can protect the HK-2 cells from DU-induced damage.