Soluble epoxide hydrolase and TRPC3 channels jointly contribute to homocysteine-induced cardiac hypertrophy: Interrelation and regulation by C/EBPβ

Objectives: Studies in certain cardiac hypertrophy models suggested the individual role of soluble epoxide hy-drolase (sEH) and canonical transient receptor potential 3 (TRPC3) channels, however, whether they jointly mediate hypertrophic process remains unexplored. Hyperhomocysteinemia promotes cardiac hypertrophy while the involvement of sEH and TRPC3 channels remains unknown. This study aimed to explore the role of, and interrelation between sEH and TRPC3 channels in homocysteine-induced cardiac hypertrophy.Methods: Rats were fed methionine-enriched diet to induce hyperhomocysteinemia. H9c2 cells and neonatal rat cardiomyocytes were incubated with homocysteine. Cardiac hypertrophy was evaluated by echocardiography, histological examination, immunofluorescence imaging, and expressions of hypertrophic markers. Epox-yeicosatrienoic acids (EETs) were determined by ELISA. TRPC3 current was recorded by patch-clamp. Gene promotor activity was measured using dual-luciferase reporter assay.Results: Inhibition of sEH by 1-trifluoromethoxyphenyl-3-(1-propionylpiperidin-4-yl) urea (TPPU) reduced ven-tricular mass, lowered the expression of hypertrophic markers, decreased interstitial collagen deposition, and improved cardiac function in hyperhomocysteinemic rats, associated with restoration of EETs levels in myocardium. TPPU or knockdown of sEH suppressed TRPC3 transcription and translation as well as TRPC3 current that were enhanced by homocysteine. Exogenous 11,12-EET inhibited homocysteine-induced TRPC3 expression and cellular hypertrophy. Silencing C/EBP beta attenuated, while overexpressing C/EBP beta promoted homocysteine-induced hypertrophy and expressions of sEH and TRPC3, resulting respectively from inhibition or activation of sEH and TRPC3 gene promoters.Conclusions: sEH and TRPC3 channels jointly contribute to homocysteine-induced cardiac hypertrophy. Homo-cysteine transcriptionally activates sEH and TRPC3 genes through a common regulatory element C/EBP beta. sEH activation leads to an upregulation of TRPC3 channels via a 11,12-EET-dependent manner.

Automated summary

This study revealed that both soluble epoxide hydrolase (sEH) and canonical transient receptor potential 3 (TRPC3) channels play a role in homocysteine-induced cardiac hypertrophy. Inhibition of sEH can alleviate pathological damage and improve cardiac function. In addition, sEH activation leads to upregulation of TRPC3 channels through an EETs-dependent manner.