Endothelin‐1‐induced COX‐2 Expression in Mouse Brain Endothelial Cells

Abstract

Endothelin‐1 (ET‐1) is a pro‐inflammatory peptide which plays important role in the pathogenesis of brain inflammatory diseases. This process may be due to the COX‐2 expression and PGE2 synthesis induced by ET‐1. However, the molecular mechanisms underlying ET‐1‐induced COX‐2 expression in mouse brain endothelial cells which contributes to inflammatory responses were largely unknown. Here, Western blotting, RT‐PCR and EIA analyses showed that ET‐1‐induced COX‐2 expression and PGE2 synthesis was attenuated by pretreatment with the inhibitors of ETB receptor (BQ788), MEK1/2 (U0126), p38 MAPK (SB202190), and JNK (SP600125), and transfection with siRNA of ERK1, p38, and JNK2. In addition, ET‐1 stimulated phosphorylation of p42/p44 MAPK, p38 MAPK, and JNK which was attenuated by the inhibitors of MEK1/2 (U0126), p38 MAPK (SB202190), and JNK (SP600125), and transfection with siRNA of ERK1, p38, and JNK2. Furthermore, ET‐1‐induced COX‐2 expression and PGE2 synthesis was inhibited by a selective NF‐κB inhibitor (Bay11‐7082). The activation of NF‐κB was consistent with IκB‐α degradation in plasma and NF‐κB translocation into nucleus in these cells. NF‐κB translocation was blocked by Bay11‐7082, U0126, SB202190, and SP600125. These results suggested that in mouse brain endothelial cells, ET‐1‐induced COX‐2 expression was mediated through phosphorylation of MAPKs and NF‐κB pathways.