Buthionine Sulfoximine, an Inhibitor of Glutathione Biosynthesis, Induces Expression of Soluble Epoxide Hydrolase and Cellular Hypertrophy Markers in a Rat Cardiomyoblast Cell Line: Roles of The NF‐κB And MAPK Signalling Pathways

Abstract

Evidence suggests that up‐regulation of soluble epoxide hydrolase (sEH) is associated with the development of cardiac hypertrophy. However, the up‐regulation mechanism is still unknown. In this study, we treated H9C2 cells with buthionine sulfoximine (BSO) to explore whether oxidative stress up‐regulates sEH gene expression and to identify the molecular mechanisms behind this up‐regulatory response. We found that BSO up‐regulated sEH at mRNA levels leading to increase in the cellular hypertrophic markers, atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP). Furthermore, BSO increased the cytosolic phosphorylated IκB‐α and translocation of NF‐κB p50 subunits. This level of translocation was paralleled by an increase in the DNA‐binding activity of NF‐κB P50 subunits. To understand the role of mitogen‐Activated Protein Kinases (MAPKs) pathway in BSO‐mediated induction of sEH mRNA, we examined the role of extracellular signal‐regulated kinase (ERK), c‐JunN‐terminal kinase (JNK) and p38 MAPK. Indeed, treatment with the ERK inhibitor, PD98059, partially blocked the activation of IκB‐α and translocation of NF‐κB p50 subunits induced by BSO. Moreover, pre‐treatment with ERK inhibitor and MEK inhibitors, U0126 and PD0325901, significantly inhibited BSO‐mediated induction of sEH and cellular hypertrophic markers gene expression. These results demonstrated that MAPK/NF‐κB signaling pathways is involved in BSO‐mediated induction of sEH gene expression. Furthermore, our findings provide strong link between sEH‐induced cardiac dysfunction and involvement of NF‐κB in the development of cellular hypertrophy.