HNF4A negatively regulated posterior capsular opacification via transcriptional inhibition of MMP2

Purpose: Posterior capsular opacification (PCO) is the most common complication after cataract surgery. Abnormal proliferation, migration, epithelial-mesenchymal transition (EMT), and extracellular matrix (ECM) synthesis of residual lens epithelial cells (LECs) cause matrix contraction and capsule shrinkage, which are considered to be the main pathogenic mechanisms of PCO. Hepatocyte nuclear factor 4α (HNF4A) has been reported to regulate EMT in different tumours. Our objective was to investigate the role and mechanism of HNF4A in PCO.Methods: HNF4A expression was tested in PCO rat lens capsules and cell models. HNF4A was knocked down using small hairpin RNA. Knockdown and overexpression of HNF4A were achieved by lentivirus in HLE-B3 cells. Cell viability was measured by Cell Counting Kit-8 assay. Cell migration ability was evaluated by wound healing and Transwell assays. EMT markers were detected by Western blotting. Transcriptome sequencing was used to screen for downstream effectors of HNF4A. Chromatin immunoprecipitation-qPCR and a dual luciferase reporter assay were used to determine the binding of HNF4A to the MMP2 promoter region.Results: HNF4A was downregulated in PCO tissue and cell models. In vitro studies showed that HNF4A deletion facilitated cell proliferation, migration, and EMT Protein Marker expression in LECs. HNF4A knockdown promoted EMT and migration of LECs via MMP2. Mechanistically, HNF4A decreased MMP2 expression by binding to the MMP2 promoter region. HNF4A deletion also promoted EMT in rat lens capsules.Conclusions: We demonstrated that HNF4A inhibited EMT of LECs by directly binding to the MMP2 promoter region and inhibiting the expression of MMP2, thus leading to retardation of PCO formation and development, suggesting that HNF4A is a potential therapeutic target for PCO.

HNF4A; MMP2; epithelial-mesenchymal; posterior capsular opacification; transforming growth factor-β.