Estrogen‐dependent epigenetic regulation of soluble epoxide hydrolase via DNA methylation

Abstract

We have demonstrated that female‐specific downregulation of soluble epoxide hydrolase (sEH) protein expression in cardiac, pulmonary, and vascular tissues favors a greater contribution of epoxyeicosatrienoic acids (EETs) in females. Thus, to elucidate molecular mechanism(s) responsible for the sexually dimorphic phenotype of sEH expression, we tested the hypothesis that female‐specific downregulation of sEH expression is driven by estrogen‐dependent methylation of the Ephx2 gene.MethodsMesenteric arteries isolated from male, female, ovariectomized female (OV) and OV with estrogen replacement (OVE) mice, as well as human cell line (HEK293T) were used.ResultsMethylation‐specific PCR (MSP) and bisulfite genomic sequencing (BGS) analysis indicate significant increases in DNA/CG methylation in vessels of female and OVE compared to those of male and OV mice. The same increase in CG methylation was also observed in male vessels incubated with a physiological concentration of 17b‐estradiol (17b‐E2) for 48 hours. All vessels that displayed increases in CG methylation were concomitantly associated with decreases in their Ephx2 mRNA and protein, suggesting a methylation‐induced gene silencing. Transient transfection assays indicate that the activity of Ephx2 promoter‐coding luciferase was significantly attenuated in HEK293T cells treated with 17b‐E2, which was prevented by additional treatment with an estrogen receptor (ER) antagonist (ICI). Chromatin immunoprecipitation (ChIP) analysis indicates significantly reduced binding activities of transcription factors (including SP1, AP‐1 and NFκB with their binding elements located in the Ephx2 promoter) in vessels of female mice and human cells treated with 17b‐E2, responses that were prevented by ICI and Decitabine (DNA methyltransferase inhibitor), respectively. In conclusion, estrogen/ER‐dependent methylation of the promoter of Ephx2 gene silences sEH expression, which is involved in specific transcription factor‐directed regulatory pathways.Support or Funding Information(This work was supported by grants NIH HL070653 and HL129797, and also partially supported by NIEHS grant R01 ES02710 and NIEHS Superfund Research Program P42 ES04699).This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.