Autophagy inhibition attenuates TGF-β2-induced epithelial-mesenchymal transition in lens epithelial cells

Aims: Autophagy has been reported to play an essential role in fibrotic disorders. Known as fibrotic cataract, posterior capsular opacification (PCO) result from pathological epithelial-mesenchymal transition (EMT) of lens epithelial cells (LECs). This study aims to identify the role and potential mechanism of autophagy in TGF-beta 2-induced EMT in LECs. Main methods: Primary rabbit LECs were treated with TGF-beta 2 to induce EMT as a model of fibrotic cataract in vitro. 3-methyladenine, chloroquine, bafilomycin Al, and gene silencing of autophagy-related protein 7 (ATG7) were treated in LECs for autophagy inhibition, while rapamycin was utilized for autophagy activation. The expression levels of EMT/autophagy-associated markers were analyzed by qRT-PCR, western blotting, immunofluorescence and transmission electron microscopy. We additionally examined cell migration ability with transwell migration assay and wound healing assay. Key findings: TGF-beta 2 promoted autophagy flux during EMT progression of LECs in a time-dependent manner. Autophagy activation by rapamycin enhanced TGF-beta 2-triggered fibrogenic responses and cell migration in LECs, whereas pharmacological inhibition of autophagy alleviated TGF-beta 2-induced increases of EMT markers and cell migration of LECs. In addition, the phosphorylation of Smad2/3 induced by TGF-beta 2 was suppressed through autophagy inhibition, while it was promoted upon autophagy activation, indicating that TGF-beta 2/Smad signaling was involved in the modulation of autophagy on EMT in LECs. Furthermore, ATG7-silenced LECs exerted antifibrosis effect induced by TGF-beta 2 through downregulation of autophagy. Significance: Intervention/inhibition of autophagy could attenuate TGF-beta 2-induced EMT in LECs, which provides autophagy-related insights on preventing and treating the fibrotic cataract or other fibrotic diseases.

Automated summary

This study demonstrated that TGF-beta 2 induces autophagy flux during EMT progression of LECs, with autophagy activation enhancing fibrogenic responses and cell migration, while autophagy inhibition alleviates EMT markers and cell migration. Additionally, modulation of Smad signaling by autophagy was observed, and ATG7-silenced LECs showed antifibrosis effect induced by TGF-beta 2. Overall, intervention/inhibition of autophagy could attenuate TGF-beta 2-induced EMT in LECs, providing insights for preventing and treating fibrotic cataracts and other fibrotic diseases.