Trichostatin A Restores Expression of Adherens and Tight Junction Proteins during Transforming Growth Factor β-Mediated Epithelial-to-Mesenchymal Transition.

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.