Mir-34a-5p Mediates Oxidative Stress In Age-related Cataract Via Regulating Nrf2/Keap1 Signal Pathway

Objectives:With the social and economic development,medical progress and the improvement of education level,the problem of population aging is becoming more and more serious.Cataract is a common senile disease.With the increase of aging,the incidence of cataract is on the rise.However,the unclear pathogenesis of cataract has become the bottleneck of its non-surgical treatment.Previous studies on the pathogenesis of cataract have showed that the occurrence of cataract is closely related to oxidative damage.It has been found that many microRNAs play a regulatory role in oxidative damage of human lens epithelial cells,and then participate in the development of cataract.However,the mechanism in this process needs to be further revealed.Therefore,this study explored whether microRNA-34a-5p mediates oxidative stress in age-related cataract and the potential pathological mechanism of microRNA-34a-5p in age-related cataract,providing new ideas and therapeutic targets for the future treatment of age-related cataract.Methods:The miR-34a-5p and the target gene was detected in the anterior capsule of clear lens and in the oxidative stress model of human lens epithelial cells,the intracellular reactive oxygen species?ROS?were also detected in human lens epithelial cells.Then,miR-34a-5p mimics,mimics control,miR-34a-5p inhibitors and inhibitors control were transfected into human lens epithelial cells B-3?HLEB-3?,respectively,the cells were exposed to 400?mol/L H₂O₂for 8h.The gene and protein was detected and the proliferation activity of cells was also detected.Results:1.miR-34a-5p and target gene?NF-E2-related factor 2,Nrf2?in lens tissue of age-related cataract:Compared with the normal group,the expression of miRNA-34a-5p in lens tissue of age-related cataract was increased significantly,the expression of Nrf2 gene was decreased significantly?P<0.001?,and the expression of Nrf2 protein in lens tissue of age-related cataract also was decreased significantly?P<0.001?.2.miR-34a-5p and target gene?Nrf2?and endogenous ROS level and cell activity in oxidative stress model:Compared with the control group,the expression of miR-34a-5p and Nrf2 in oxidative stress model was increased significantly,while the expression of Nrf2 gene was decreased significantly.The abnormal expression of microRNAs-34a-5p and Nrf2 was increased with time?P<0.001?,and the expression of Nrf2protein in oxidative stress model also was decreased significantly?P<0.001?.In addition,compared with the control group,the level of endogenous ROS in oxidative stress model was increased significantly,and cell activity was decreased significantly.With the prolongation of time,the level of endogenous ROS and abnormal cell activity became more obvious?P<0.001?.3.Effect of microRNA-34a-5p on endogenous ROS level and proliferation of HLEB-3 cells:After the infection of HLEB-3 with mir-34a-5p mimics,the level of mir-34a-5p was increased significantly,the level of Nrf2gene and protein was decreased significantly,the level of endogenous ROS was increased significantly,and the cell proliferation activity was decreased significantly?P<0.001?.However,after infection with HLEB-3 by the inhibitor of miR-34a-5p,the level of miR-34a-5p was decreased significantly,the level of Nrf2 was increased significantly,the level of endogenous ROS was decreased significantly,and the cell proliferation activity was increased significantly?P<0.001?.4.Nrf2isthetargetgeneof microRNA-34a-5p:miR-34a-5p inhibited luciferase activity by 3'UTR of wild-type Nrf2?P<0.01?.In addition,mir-34a-5p did not inhibit luciferase activity by 3'UTR of mutant Nrf2?P>0.01?.Conclusions:miR-34a-5p can increase oxidative stress of lens epithelial cells and inhibit the activity of lens epithelial cells through Nrf2/Keap1 signaling pathway,thus participating in the process of age-related cataract.