ABSTRACT
Objective To detect the expression of miR-138 in lens tissues of agerelated cataract and explore the effects of miR-138 on the proliferation and apoptosis of human lens epithelial cells and its possible target genes.Methods Real-time quantitative PCR (RT-qPCR) was applied for the detection of the expression of miR-138 and prediction of target gene sirtuin (silent information regulator 1) (SIRT1) in patients with age-related cataract (cataract group) and anterior lens capsules (normal control group).Then miR-138 mimics,mimic controls,miR-138 inhibitors and inhibitor controls were transfected into the human lens epithelial cell line (SRA01/04),and the expression of SIRT1 mRNA and protein was detected by RT-qPCR and Western blot,accordingly.At 72 hours after transfection,the cells were exposed to 200 μmol · L-1 H2O2 for 1 hour,followed by detection of the activity of Caspase-3 by the Caspase-3 activity assay kit,and identification of the targeted relationship between miR-138 and SIRT1 by dual luciferase reporter assays.Results Compared with the normal control group,the expression of miR-138(3.64 ±0.19) was significantly increased (P ＜0.001),but the expression of SIRT1 mRNA(0.32 ± 0.06) was significantly decreased (P ＜ 0.001) in the cataract group.Moreover,The expression levels of SIRT1 mRNA(0.42 ± 0.05) and protein(0.46 ± 0.05) in cells transfected with miR-138 mimics were significantly decreased,while the activity of Caspase-3 (3.24 ± 0.17) was significantly elevated when compared with cells transfected with minic controls (all P ＜ 0.05);Compared with cells transfected with inhibitor controls,the expressions of SIRT1 mRNA(2.95 ±0.13) and protein(1.98 ±0.12) were significantly upregulated,whereas Caspase-3 activity(0.42 ±0.05) was significantly decreased in cells transfected with miR-138 inhibitors (all P ＜0.05).And fmally,dual luciferase reporter assays showed the confirmation SIRT1 as a direct target of miR-138.Conclusion miR-138 is highly expressed in the lens capsule of age-related cataract patients,and it can promote the apoptosis of lens epithelial cells by negatively regulating the expression of SIRT1.
ABSTRACT
·AIM:To investigate the effects and mechanism of miR-138 in mediating the antioxidant function of lens epithelial cells affected by age-related cataracts. ·METHODS:Real-time quantitative PCR(RT-qPCR) was used to detect miR-138 expression in the anterior lens capsules of healthy people, the anterior lens capsules of patients with age-related cataracts, and human epithelial cell line (SRA01/04) cells exposed to oxidative stress. A 2',7'-dichloro-fluorescein diacetate (DCFH-DA) probe was used to measure the levels of endogenous reactive oxygen species (ROS) in human lens epithelial cells (hLECs) exposed to 400μ mol/L H2O2for 1h. SRA01/04 cells were transfected with either miR-138 mimics,mimic controls, miR-138 inhibitors or inhibitor controls. After 72h,these cells were exposed to 400μ mol/L H2O2for 1h, then p53 and Bax mRNA expression were measured using RT-qPCR. Expression of p53 and Bax protein were also measured by western blotting analysis. Finally, cell viability was assessed using an MTS assay. ·RESULTS: Compared to the control group, expression of miR-138 in the anterior lens capsules of age-related cataract patients and in SRA01/04 cells exposed to oxidative stress significantly increased (P<0.001). Levels of endogenous ROS were significantly elevated in hLECs exposed to oxidative stress (P<0.001). Compared to the mimic control group, the hLECs in the miR-138 mimic group expressed significantly higher levels of p53 and Bax mRNA and protein while cell viability was significantly reduced(P<0.001). Conversely, p53 and Bax mRNA and protein expression were significantly reduced in the miR-138 inhibitor group as compared to the control group, while the cells in this group had much higher levels of cell viability (P<0.001). · CONCLUSION: The expression of miR - 138 is upregulated in the anterior lens capsules of age-related cataract patients. MiR-138 decreases the anti-oxidative stress capacity of lens epithelial cells by upregulating p53 and Bax, while inhibiting cell proliferation and repair. This finding suggests that miR-138 may play a key role in the development of age-related cataracts.