Epigenetic modulation of radiation-induced DGKA expression prevents pro-fibrotic fibroblast response.

Differential methylation at an enhancer of diacylglyerol kinase alpha (DGKA) in normal dermal fibroblasts was found to be associated with radiation-induced fibrosis. After irradiation, the transcription factor EGR1 is induced and binds to the hypomethylated enhancer, leading to increased DGKA and pro-fibrotic marker expression. We now modulated this DGKA induction by targeted genomic editing of the DGKA enhancer and administering epigenetic drugs. Editing the binding-sites of the stress-inducible transcription factor EGR1 at the DGKA enhancer by a targeted CRISPR/Cas9 approach decreased radiation-induced DGKA and pro-fibrotic marker expression. A transcriptome analysis was performed with edited BJ cells to identify potential genome-wide consequences caused by the loss of EGR1-binding at the DGKA enhancer. Antibody-guided chromatin tagmentation (ACT)-seq was also used to analyze the change of histone marks H3K27ac and H3K27me3 when treated with epigenetic inhibitors. Our results reveal how epigenetic regulation of the DGKA enhancer region contributes to pro-fibrotic reactions.