To investigate the effect of microRNA-27b-3p (miR-27b-3p)/nuclear factor-E2-related factor 2 (Nrf2) on metabolic memory impairment of human retinal pigment epithelial (RPE) cells and to explore its regulatory mechanism.

ARPE-19 cells were divided into normal control group, metabolic memory group, miR-27b-3p control group, miR-27b-3p inhibitor group, and liraglutide group.Cells in normal control group were cultured in 5.5 mmol/L normal glucose medium for 6 days.Cells in metabolic memory group were cultured in 30 mmol/L glucose for 3 days and changed to 5.5 mmol/L for 3 days.Cells in miR-27b-3p inhibitor group were added with puromycin after lentiviral transfection to select the successfully transfected cells, and were cultured in 30 mmol/L glucose for 3 days then 5.5 mmol/L glucose for 3 days.Cells in liraglutide group were cultured in 30 mmol/L glucose with liraglutide for 3 days then 5.5 mmol/L glucose for 3 days.The regulatory relationship between miR-27b-3p and Nrf2 was verified by lentiviral transfection.Expressions of miR-27b-3p, Nrf2, NAD(P)H dehydrogenase[quinone]1 (NQO1), heme oxygenase-1 (HO-1) mRNA and protein levels were analyzed by real-time quantitative PCR.Total and nuclear Nrf2 protein expressions were detected by Western blot.The cell proliferation rates of various groups were determined by cell counting kit-8 (CCK-8).The reactive oxygen species (ROS) level was detected by the DHE kit.

The miR-27b-3p mRNA relative expression of normal control group, metabolic memory group, miR-27b-3p control group, miR-27b-3p inhibitor group was 1.000±0.000, 1.881±0.034, 1.683±0.088 and 0.111±0.008, respectively, with a statistically significant difference (F=850.815, P<0.001).The miR-27b-3p mRNA relative expression level was lower in normal control group than in metabolic memory group, lower in miR-27b-3p inhibitor group than in normal control group, and the differences were statistically significant (both at P<0.01).The expression levels of Nrf2 mRNA, total protein, and nuclear protein were decreased in metabolic memory group in comparison with normal control group and were significantly increased in miR-27b-3p inhibitor group in comparison with miR-27b-3p control group, showing statistically significant differences (all at P<0.01).The NQO1 and HO-1 mRNA expressions were decreased in metabolic memory group in comparison with normal control group, and were significantly higher in miR-27b-3p inhibitor group compared with miR-27b-3p control group, showing statistically significant differences (all at P<0.01).The fluorescence intensity of Nrf2, NQO1, and HO-1 was lower in metabolic memory group than in normal control group, and was higher in miR-27b-3p inhibitor group than in miR-27b-3p control group, showing statistically significant differences (all at P<0.01).Compared with metabolic memory group, the relative expression of miR-27b-3p mRNA declined in liraglutide group, with a statistically significant difference (P<0.05).The relative expression levels of Nrf2 mRNA, NQO1 mRNA, HO-1 mRNA, total and nuclear Nrf2 protein of liraglutide group were enhanced in comparison with metabolic memory group, with statistically significant differences (all at P<0.05).The fluorescence intensity of Nrf2, NQO1, and HO-1 was enhanced in liraglutide group in comparison with metabolic memory group, and the differences were statistically significant (all at P<0.05).Compared with normal control group and liraglutide group, the cell proliferation viability was decreased in metabolic memory group, and the differences were statistically significant (both at P<0.01).The relative content of ROS was higher in metabolic memory group than in normal control group and liraglutide group, and the difference was significant (all at P<0.01).

Liraglutide reverses the inhibition of metabolic memory on Nrf2, NQO1, and HO-1 by downregulating miR-27b-3p.

Diabetic retinopathy; Liraglutide; Retinal pigment epithelium; Metabolic memory; MicroRNA-27b-3p; Nrf2