Soluble epoxide hydrolase inhibitors improve angiogenic function of endothelial progenitor cells via ERK/p38-mediated miR-126 upregulation in myocardial infarction mice after exercise

It is well established that exercise could protect against myocardial infarction (MI). Previously, we found that epoxyeicosatrienoic acids (EETs) could be induced by exercise and has been found to protect against MI via promoting angiogenic function of endothelial progenitor cells (EPCs). However, the underling mechanism of EETs in promoting EPC functions is unclear. C57BL/6 mice were fed with a novel soluble epoxide hydrolase inhibitor (sEHi), TPPU, to increase EET levels, for 1 week before undergoing MI surgery. Mice were then subjected to exercise training for 4 weeks. Bone marrow-derived EPCs were isolated and cultured in vitro. Exercise upregulated miR-126 expression but downregulated the protein levels of its target gene, Spred1, in EPCs from MI mice. TPPU further enhanced the effects of exercise on EPCs. Spred1 overexpression abolished the protective effects of TPPU on EPC functions. Downregulation of miR-126 by antagomiR-126 impaired the inhibitor effects of TPPU on Spred1 mRNA and protein expression. Additionally, TPPU upregulated miR-126 is partially mediated through ERK/p38 MAPK pathway. This study showed that sEHi promoted miR-126 expression, which might be related to the beneficial effect of sEHi on EPC functions in MI mice under exercise conditions, by increasing ERK and p38 MAPK phosphorylation and inhibiting Spred1.