Homocysteine upregulates soluble epoxide hydrolase in vascular endothelium in vitro and in vivo

Donghong Zhang, Xina Xie, Yequn Chen, Bruce D. Hammock, Wei Kong, Yi Zhu

Research output: Contribution to journalArticle

62 Scopus citations

Abstract

Rationale: Hyperhomocysteinemia is a risk factor of atherogenesis. Soluble epoxide hydrolase (sEH) is a major enzyme that hydrolyzes epoxyeicosatrienoic acids and attenuates their cardiovascular protective effects. Whether homocysteine (Hcy) regulates sEH and the underlying mechanism remains elusive. Objective: To elucidate the mechanism by which Hcy regulates sEH expression and endothelial activation in vitro and in vivo. Methods and Results: Hcy treatment in cultured human endothelial cells dose-dependently and time-dependently upregulated sEH mRNA and protein. Hcy increased the expression of adhesion molecules, which was markedly reversed by inhibiting sEH activity. Hcy-induced sEH upregulation is associated with activation of activating transcription factor-6 (ATF6). Bioinformatics analysis revealed a putative ATF6-binding motif in the promoter region of the sEH gene, which was found at a methylation site. Site-directed mutagenesis and chromatin immunoprecipitation assays demonstrated that Hcy treatment or ATF6 overexpression promoted ATF6 binding to the promoter of sEH and increased its activity. Results of methylation-specific polymerase chain reaction revealed that the ATF6 binding site on the sEH promoter was partially methylated and was demethylated with Hcy. SiRNA knockdown of ATF6α or SP1 blocked and ATF6 overexpression and DNA methyltransferase inhibitor mimicked the effect of homocysteine on sEH upregulation. In vivo, immunofluorescence assay revealed elevated expression of sEH and adhesion molecules in the aortic intima of mice with mild hyperhomocysteinemia, which was attenuated by sEH deletion or inhibition. Conclusion: ATF6 activation and DNA demethylation may coordinately contribute to Hcy-induced sEH expression and endothelial activation. Inhibition of sEH may be a therapeutic approach for treating Hcy-induced cardiovascular diseases.

Original languageEnglish (US)
Pages (from-to)808-817
Number of pages10
JournalCirculation Research
Volume110
Issue number6
DOIs
StatePublished - Mar 16 2012

Keywords

  • activating transcription factor 6
  • demethylation
  • endothelial cells
  • homocysteine
  • soluble epoxide hydrolase

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine

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