Thioredoxin‐1 regulates the autophagy induced by oxidative stress through LC3‐II in human lens epithelial cells

Abstract

Oxidative stress plays a major role in age‐related cataract development. The cellular antioxidant protein thioredoxin‐1 (Trx‐1) and its negative regulator, thioredoxin binding protein‐2 (TBP‐2), are pivotal in the cellular redox balance during oxidative stress. The aim of this study is to investigate the effect of Trx‐1 and TBP‐2 on LC3 I/LC3 II in oxidative stress‐induced autophagy in human lens epithelial cells (LECs). In our study, LECs were treated with 50 μM H2O2 for different durations, and the expression of Trx‐1 and TBP‐2 were measured by RT‐PCR and Western blot. Trx‐1 activity was evaluated by the thioredoxin activity fluorescent assay. The subcellular localization of Trx‐1 and TBP‐2 was evaluated by cellular immunofluorescence. The interaction between Trx‐1 and TBP‐2 was examined by co‐immunoprecipitation. The cell viability was detected using CCK‐8, and the expression of LC3‐II/LC3‐I was detected to evaluate the autophagy. The results showed that the mRNA levels of the Trx‐1 and TBP‐2 were kinetically changed after treatment with H2O2 for different durations. Exposure to H2O2 increased the expression of TBP‐2 but not Trx‐1, while the exposure inhibited Trx‐1 activity. TBP‐2 was co‐localized with Trx‐1, and exposure to H2O2 increased the interaction between TBP‐2 and Trx‐1. Trx‐1 overexpression enhanced the autophagic response under normal circumstances and it might regulate autophagy in the initial phase. This study demonstrates the differential role of Trx‐1 in cellular oxidative stress response, oxidative stress increased Trx‐1 interaction with TBP‐2, and Trx‐1/TBP‐2 regulated the autophagic response in the initial phase through LC3‐II.