Effect of hypoxia on expressions of stromal cell-derived factor-1 and integrin-linked kinase in retinal pigment epithelium cell in vitro / 中华实验眼科杂志

ABSTRACT

Background Hypoxia is a crucial factor of neovascularization.Many researches found that stromal cell-derived factor-1 (SDF-1) and integrin-linked kinase (ILK) play an important role in the neovascular disease.However,effect of SDF-1 and ILK in eye neovascular disease is below understood.Objective The aim of this study was to investigate the effect of hypoxia on the expressions of SDF-1 and ILK in cultured retinal pigment epithelium(RPE) cells in vitro.Methods RPE tissue was isolated from 4-week-old C57BL/6 mouse and was digested and cultured in DMEM/F12 with 10％ fetal bovine serum (FBS).The cells with 80％ confluence were collected and passaged.The third generation of cells were identified with cytokeratin 18 (CK18) antibody by immunochemistry.The cells were inoculated at the density of 5×104 cells/ml to free-serum DMEM/F12 for 24 hours and then were cultured in regular medium in the normoxic control group.RPE cells were cultured for 1 hour and 3,6,12,24,48,72 hours with 200 μmol/L CoCl2 in the hypoxia group.Reverse transcription-PCR(RT-PCR) was used to evaluate the expressing change of SDF-1 mRNA and ILK mRNA in RPE cells,and Western blot was used to assay the expressing change of SDF-1 protein and ILK protein in RPE cells in different time points.The detected outcomes were represented as the ratio of target gene A value/β-actin A value.Results Cultured cells showed the polygon in shape with the black pigment granules in cytoplasm.Over 90％ cells were positive response for CK18.Expressions of the SDF-1 mRNA and ILK mRNA were increased in different time points after CoCl2 co-cultured(SDF-1 mRNAF=281.875,P=0.000 ;ILK mRNA F=187.566,P=0.000),with the highest expressing value in hypoxia at 12 hours.No significant change in the expression of SDF-1 mRNA and protein was found 1 hour after CoCl2 co-cultured,but expressions of SDF-1 mRNA and ILK mRNA were significantly higher in 3,6,12,24,48 and 72 hours than the normoxic control group(P＜0.01).The expressions of SDF-1 protein and ILK protein were gradually ascended with the time increase of CoCl2 co-culture,showing a significant difference among different time points(SDF-1 F=44.719,P =0.000 ; ILK F =144.481,P =0.000),and the up-regulation of SDF-1 protein and ILK protein expression was seen mainly in 3,6,12,24,48 and 72 hours after CoCl2 co-cultured in comparison with the normoxic control group (P＜0.01).Conclusions SDF-1 and ILK are involved in the hypoxic response of RPE cells and may play a potential role in ischemic/hypoxic retinopathy.