Effect of HES5 on transdifferentiation and apoptosis of renal tubular epithelial cells and its underlying mechanism

To investigate the effect of hairy and enhancer of split 5 (HES5) on transdifferentiation and apoptosis of renal tubular epithelial cells induced by TGF-β1 and its potential mechanism.

The differentially expressed genes in GSE66494 data were analyzed and screened. The mouse model of unilateral uretera obstruction (UUO) was established, and the expression level of HES5 was detected in the renal tissue. HK-2 cells were treated with 10 ng/mL TGF-β1 for 24 h to establish a tubular epithelial-mesenchymal transition (EMT) model, and then qRT-PCR and Western blotting were performed to detect the expression of HES5 at mRNA and protein levels. After HK-2 cells were transfected with the plasmid overexpressing HES5, the protein levels of fibronectin, collagen Ⅰ, vimentin, apoptosis markers Bax and Bcl2 were detected in 24 h later. Then, HK-2 cells were divided into Control group, siHES5 group, TGF-β1 group, and siHES5+TGF-β1 group. The protein level of fibrosis and apoptosis markers were measured in above groups with Western blotting. TUNEL staining and flow cytometry were employed to detect cell apoptosis. Western blotting was applied to determine the protein levels of AKT, p-AKT, PI3K and p-PI3K. HK-2 cells overexpressing HES5 were treated with PI3K inhibitor LY294002, and the expression of vimentin was detected.

The expression of HES5 was significantly up-regulated in both chronic kidney disease (CKD) and fibrotic kidneys of mice. Overexpression of HES5 promoted the synthesis of fibronectin, collagen Ⅰ, vimentin and Bax in HK-2 cells, and inhibited the expression of Bcl2 (P<0.05). HES5 knockdown not only down-regulated the expression of fibrosis markers, but also inhibited the apoptosis of HK-2 cells. Furthermore, HES5 knockdown inhibited the activation of PI3K/AKT signaling pathway induced by TGF-β1 in HK-2 cells (P<0.05). Inhibitors of the PI3K/AKT signaling pathway inhibitor attenuated the induction of HES5 on vimentin.

HES5 knockdown inhibits the transdifferentiation and apoptosis in TGF-β1-induced renal tubular epithelial cells, which may be related to the decreased activity of the PI3K/AKT signaling pathway.