MiR-15b-5p alleviates hypoxia/reoxygenation-induced human renal tubular epithelial cell HK-2 injury by targeting FOXO1
Objective To investigate the role and underlying mechanism of miR-15b-5p on hypoxia/reoxygenation(H/R)induced human renal tubular epithelial cell(HK-2)injury by targeting forkhead box O1(FOXO1).Methods HK-2 cells in the log growth phase were set up as follows:(1)control group(normal culture)and H/R group(H/R induced culture).The expressions of miR-15b-5p and FOXO1 mRNA were detected using qRT-PCR,and the protein expression of FOXO1 was detected using Western blotting.(2)Control group(normal culture),H/R group(H/R induced culture),H/R+mimic control group(cells transfected with mimic control then induced by H/R),H/R+miR-15b-5p mimic group(cells transfected with miR-15b-5p mimic then induced by H/R),H/R+miR-15b-5p mimic+OE-NC group(cells co-transfected with miR-15b-5p mimic and OE-NC plasmid,then induced by H/R),and H/R+miR-15b-5p mimic+OE-FOXO1 group(cells co-transfected with miR-15b-5p mimic and FOXO1 overexpression plasmid,then induced by H/R).The expression of miR-15b-5p was detected using qRT-PCR,and the protein expressions of FOXO1,cleaved caspase-3,Bax,and Bcl-2 were detected using Western blotting.CCK-8 assay was used to detect cell viability.Cell apoptosis was measured by the TUNEL method.(3)Control group(normal culture),H/R group(H/R induced culture),H/R+miR-15b-5p mimic group(cells transfected with miR-15b-5p mimic then induced by H/R),and H/R+miR-15b-5p mimic+OE-FOXO1 group(cells co-transfected with miR-15b-5p mimic and FOXO1 overexpression plasmid,then induced by H/R).The protein expressions of LC3,p62 and Beclin1 were detected using Western blotting.LC3 immunofluorescence was used to detect the cell autophagy.The target reaction between miR-15b-5p and FOXO1 was assessed using dual luciferase reporting assay.Results Under an inverted microscope,it was observed that the control group had a higher number of cells,most of which were in a typical cobblestone shape and grew in a cobblestone-like manner;most of the cells in the H/R group contracted and became round,with a significant decrease in the number of adherent cells.In H/R-induced HK-2 cells,miR-15b-5p was significantly down-regulated,while miRNA and protein expression of FOXO1 was up-regulated(P<0.05).Luciferase assay results showed that miR-15b-5p directly targeted the 3'-UTR of FOXO1.Overexpression of miR-15b-5p increased cell viability,reduced cell apoptosis,and decreased autophagy in H/R-induced HK-2 cells(P<0.05).Compared with H/R+miR-15b-5p mimic group,the viability of HK-2 cells was decreased,the apoptosis and autophagy level were increased in H/R+miR-15b-5p mimic+OE-FOXO1 group(P<0.05).Conclusion miR-15b-5p inhibited autophagy and alleviated H/R-induced HK-2 cell injury by targeting FOXO1.