Abstract
Purpose :
Epithelial-to-mesenchymal transition (EMT) of lens epithelial cells is involved in the development of fibrotic cataract. Ocular growth factors and cytokines such as fibroblast growth factor (FGF) and transforming growth factor-beta (TGF-β) have been shown to regulate and/or dysregulate lens epithelial cell (LEC) regulatory processes, including proliferation, fibre differentiation and EMT. Here we tested the hypothesis that FGF-2 differentially potentiates lens epithelial TGF-β-induced EMT in the rodent lens.
Methods :
Postnatal 21-day-old rat LEC explants treated with TGF-β2 (50 pg/ml) to induce EMT, and/or co-treated with FGF-2 (150 ng/ml), were monitored over a 5-day culture period, comparing central and peripheral regions. Changes in levels of EMT marker α-SMA and fibre differentiation/elongation markers including β-crystallin were examined using immunolabeling, as well as canonical TGF-β signaling (Smads 2/3) at 2 hours. Western blotting was also used to compare LEC protein expression levels.
Results :
Compared to LECs treated with only TGF-β2, we show that the addition of a high fibre differentiating dose of FGF-2 differentially impacted TGF-β2-treated LECs after 5 days of culture; with central LECs undergoing TGF-β2-induced EMT, whereas peripheral LECs primarily undergoing lens fibre-cell elongation in place of EMT. This co-treatment with FGF-2 and TGF-β2 retained labelling for α-SMA in central LECs with little to no β-crystallin; however, β-crystallin was most prominent in peripheral LECs. Interestingly, FGF did not potentiate nuclear translocation of Smad2/3 in TGF-β-treated LECs by 2 hours of culture.
Conclusions :
The current study showed an important role for FGF-2 in potentiating EMT in TGF-β2-treated LECs, in a spatially dependent manner. This provides a new perspective for the role of FGF-2 in lens, in particular its role in the modulation of TGF-β2-induced EMT leading to cataract.
This is a 2021 ARVO Annual Meeting abstract.