Abstract
Purpose:Adherens junctions and polarity markers play an important role in maintaining epithelial phenotype but get altered during the epithelial-mesenchymal transition (EMT). Alterations of these markers during EMT of lens epithelial cell (LEC) can lead to vision compromising conditions. The aim of this study was to examine if Trichostatin-A (TSA), a histone deacetylase inhibitor, can prevent EMT by restoring the adherens junction complex in LEC.Methods:Fetal human lens epithelial cell line (FHL124) was used. Cells were treated with 10 ng/ml TGF-β2 in the presence or absence of TSA. Real time-PCR and western blotting were carried out for HDAC1, HDAC2, CDH1 (E-cad), TJP1 (ZO-1) and CTNNB1 (β-cat). Level of histone acetylation was analyzed by western blotting. Chromatin Immunoprecipitation was carried out to study the level of acetylated histone H4 and HDAC2 at the promoter regions of CDH1, TJP1, and CTNNB1. E-cad, ZO-1, and β-cat were localized using immunofluorescence. Kruskal-Wallis test was used for statistical analysis.Results:TSA down-regulated HDAC1 and HDAC2 and led to an increase in global acetylation. The mRNA and protein levels of E-cad, ZO-1, and β-cat decreased during EMT but were up-regulated by TSA treatment. TSA also helped in stabilizing these proteins at cell-cell junctions during EMT. TSA decreases association of HDAC2 at the promoter regions of adherens junction genes while increasing histone H4 acetylation status.Conclusion:TSA increases histone acetylation and restores the adherens junction complex in LECs. TSA helps in preventing EMT and thus shows potential against lens fibrosis and vision compromising conditions.
Highlights
During epithelial‐to‐mesenchymal transition (EMT), TSA treatment maintained the cuboidal morphology of lens epithelial cell (LEC) and suppressed the effects of TGF‐β2. (Credit: Source‐ Eye (Lond) 2015; 29(6): 828‐838.)[20]
We report here that epigenetic modifications such as histone acetylation help in restoring adherens junction complexes and help in EMT prevention
Results presented here are the first to support the proposal that TSA, an histone deacetylases (HDACs) inhibitor, can regulate gene expression for E‐cad, zonula occludens‐1 (ZO‐1), and β‐cat by modulating histone acetylation status at their promoter regions during TGF‐β‐mediated EMT in LECs
Summary
Beta‐catenin (β‐cat) binds to E‐cad and helps in cell‐cell adhesion.[2] Together, E‐cad, ZO‐1 and β‐cat form the adherens junction complex The loss of this complex is characteristic of epithelial‐to‐mesenchymal transition (EMT), a process by which epithelial cells trans‐differentiate into motile myofibroblast‐like cells.[3] Transforming growth factor beta (TGF‐β) is considered to be a key inducer of EMT‐related changes in the human lens, and is associated with complications like subcapsular cataracts and posterior capsular opacification (PCO).[4,5] During EMT, lens epithelial cells (LECs) trans‐differentiate into spindle‐shaped cells that express a high level of mesenchymal markers and a reduced level of epithelial markers.[4,6,7,8]
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