HES5对肾小管上皮细胞转分化和凋亡的影响及其机制研究

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

目的探讨HES5(hairy and enhancer of split 5)对TGF-β1诱导的肾小管上皮细胞转分化和凋亡的作用及其潜在机制。方法分析和筛选GSE66494数据中的差异表达基因。建立小鼠的输尿管梗阻模型(unilateral uretera obstruction,UUO),检测肾组织中HES5的表达水平。TGF-β1(10 ng/mL)处理HK-2细胞24 h建立肾小管上皮-间质转化模型后,通过qRT-PCR和Western blot检测HES5的表达水平。用过表达HES5的质粒转染HK-2细胞,24 h后检测其纤连蛋白(Fibronectin,FN)、胶原蛋白Ⅰ(CollagenⅠ)和波形蛋白(Vimentin)及凋亡相关标志物(Bax、Bcl2)等蛋白表达;然后,将HK-2细胞分为4组:Control组、siHES5组、TGF-β1组、siHES5+TGF-β1组,检测各组的纤维化及凋亡标志物的表达情况。运用TUNEL及流式细胞术检测各组细胞的凋亡情况。Western blot检测各组AKT、p-AKT、PI3K、p-PI3K的蛋白表达。通过加入PI3K抑制剂(LY294002)处理过表达HES5的HK-2细胞后,检测Vimentin的表达。结果HES5的表达在慢性肾脏病(chronic kidney disease,CKD)和小鼠纤维化肾组织中均显著上调;过表达HES5可以促进HK-2细胞中FN、CollagenⅠ、Vimentin、Bax的合成,抑制Bcl2的表达(P<0.05);敲低HES5不仅下调纤维化标志物的表达,还抑制了肾小管上皮细胞凋亡;此外,HES5基因敲低使TGF-β1诱导的HK-2细胞内PI3K/AKT信号通路的激活程度降低(P<0.05);PI3K/AKT信号通路抑制剂减弱了HES5对Vimentin的诱导作用。结论敲低HES5可以抑制TGF-β1诱导的肾小管上皮细胞转分化和凋亡,这可能与PI3K/AKT信号通路活性降低有关。

Objective 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.Methods 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,collagenⅠ,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.Results 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,collagenⅠ,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.Conclusion 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.