High uric acid induces phenotypic transition of renal tubular cells via PI3K/Akt signaling pathway / 中华肾脏病杂志

ABSTRACT

Objective To investigate the effect and the mechanism of epithelial-mesenchymal transition (EMT) in renal tubular cells induced by uric acid.Methods Normal rat kidney tubular cell line (NRK-52E) were exposed to different concentrations of uric acid (100,200,400,600,800 μmol/L UA) for 48 hours to induce EMT.Morphological changes of the NRK-52E cells were examined under an inverted phase contrast microscope.The protein expression of E-cadherin,α-SMA,p-Akt and Akt were detected by Western blotting.The distribution of E-cadherin and α-SMA were detected by immunofluorescence.NRK-52E cells were pretreated by different concentrations of LY294002(0,2.5,5,10,15 μmol/L),the inhibitor of PI3K/p-Akt signaling pathway,and then processed by uric acid (400 μmol/L) for 48 hours.Western blotting was used to detect the protein expression of p-Akt and Akt.NRK-52E cells were then divided into four groupsnormal group (N),uric acid group (UA),LY294002 group (LY),uric acid with LY294002 group (UA + LY).The protein expression of E-cadherin and α-SMA were detected by Western blotting,the distribution of E-cadherin,α-SMA and p-Akt were detected by immunofluorescence.Results There was abundant cellular expression of E-cadherin in unstimulated renal tubular cells whereas its expression was significantly decreased in uric acidstimulated cells (P ＜ 0.05).In addition,uric acid induced de novo expression of α-SMA in contrast to almost negative staining in untreated cells (P ＜ 0.05).p-Akt were obviously increased in high uric acid group (P ＜ 0.05) and Akt changed not significantly (P ＞ 0.05).NRK-52E cells transformed into elongated fibroblast-like cells from cuboidal clustered epithelial cells.These indicated that uric acid has induced EMT and activated PI3K/p-Akt signaling pathway in NRK-52E cells.However,the above effects of uric acid were abolished when p-Akt was blocked by the PI3K inhibitor (10,15 μmol/L LY294002),indicated that LY294002 has reversed the trend of EMT.Conclusions High uric acid induces phenotypic transition of renal tubular cells probably via activating PI3K/Akt signaling pathway.