Epigenetic alterations associated with dexamethasone sodium phosphate through DNMT and TET in RPE cells.

Purpose: To elucidate the mechanism behind epigenetic alteration associated with dexamethasone (DEX) sodium phosphate treatment. Methods: We performed enzyme-linked immunosorbent assay to quantify changes in global DNA methylation and hydroxymethylation, quantitative real-time PCR (qRT-PCR) of the DNA methylation- and hydroxymethylation-related gene, in vitro DNA methyltransferase (DNMT) enzymatic activity assays with purified DNMTs, and DNA hydroxymethylation pattern with super-resolution imaging. Results: We identified global DNA hypomethylation and hyper-hydroxymethylation upon DEX treatment, associated with aberrant mRNA expression levels of DNMT and ten-eleven translocation (TET) proteins. Additionally, DEX exposure could directly hinder DNMT activities. Conclusions: We showed that DEX-induced epigenetic alterations are linked to aberrant DNMT and TET expression, potentially through an essential role of DNMT.

Human Antigen R -mediated modulation of Transforming Growth Factor Beta 1 expression in retinal pathological milieu.

The fate and stability of messenger RNA (mRNA), from transcription to degradation is regulated by a dynamic shuttle of epigenetic modifications and RNA binding proteins in maintaining healthy cellular homeostasis and disease development. While Transforming Growth Factor Beta 1 (TGFß1) has been implicated as a key regulator for diabetic retinopathy, a microvascular complication of diabetes, the RNA binding proteins post-transcriptionally regulating its expression remain unreported in the ocular context. Further, dysfunction of TGFß1 signalling is also strongly associated with angiogenesis, inflammatory responses and tissue fibrosis in many eye conditions leading to vision loss. In this study, computational and molecular simulations were initially carried out to identify Human Antigen R (HuR) binding sites in TGFß1 mRNA and predict the structural stability of these RNA-protein interactions. These findings were further validated through in vitro experiments utilizing Cobalt Chloride (CoCl2) as a hypoxia mimetic agent in human retinal microvascular endothelial cells (HRMVEC). In silico analysis revealed that HuR preferentially binds to the 5'-UTR of TGFß1 and displayed more stable interaction than the 3'UTR. Consistent with in silico analysis, RNA immunoprecipitation demonstrated a robust association between HuR and TGFß1 mRNA specifically under hypoxic conditions. Further, silencing of HuR significantly reduced TGFß1 protein expression upon CoCl2 treatment. Thus, for the first time in ocular pathological milieu, direct evidence of HuR- TGFß1 mRNA interaction under conditions of hypoxia has been reported in this study providing valuable insights into RNA binding proteins as therapeutic targets for ocular diseases associated with TGFß1 dysregulation.