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Prostaglandin E 2 ‐induced intercellular adhesion molecule‐1 expression is mediated by cAMP/Epac signalling modules in bEnd.3 brain endothelial cells
Author(s) -
Park Tae Yeop,
Baik Eun Joo,
Lee Soo Hwan
Publication year - 2013
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/bph.12103
Subject(s) - intercellular adhesion molecule 1 , prostaglandin e , forskolin , activator (genetics) , microbiology and biotechnology , signal transduction , cell adhesion molecule , protein kinase a , chemistry , ly294002 , kinase , biology , receptor , pi3k/akt/mtor pathway , endocrinology , biochemistry
Background and Purpose Prostaglandin E 2 ( PGE 2 ) has been implicated in the regulation of adhesion molecules, leukocyte adhesion and infiltration into inflamed site. However, the underlying mechanism therein involved remains ill‐defined. In this study, we explored its cellular mechanism of action in the regulation of the intercellular adhesion molecule‐1 ( ICAM ‐1) expression in the brain endothelial cells. Experimental Approach bEnd.3 cells, the murine cerebrovascular endothelial cell line and primary mouse brain endothelial cells were treated with PGE 2 with or without agonists/antagonists of PGE 2 receptors and associated signalling molecules. ICAM ‐1 expression, A kt phosphorylation and activity of NF ‐κ B were determined by reverse transcription polymerase chain reaction ( RT‐PCR ), immunoblot analysis, luciferase assay and immunocytochemistry. Key Results PGE 2 significantly up‐regulated the expression of ICAM ‐1, which was blocked by EP4 antagonist ( ONO ‐ AE2 ‐227) and knock‐down of EP4 . PGE 2 effects were mimicked by forskolin, dibutyryl cAMP ( dbcAMP ) and an exchange protein directly activated by cAMP ( E pac) activator (8‐ C pt‐ cAMP ) but not a protein kinase A activator ( N 6 ‐ B nz‐ cAMP ). PGE 2 ‐induced ICAM ‐1 expression was reduced by knock‐down of E pac1. A PI3K specific inhibitor ( LY294002 ), A kt inhibitor VIII ( A kti) and NF ‐ κB inhibitors (Bay‐11–7082 and MG ‐132) attenuated the induction of ICAM ‐1 by PGE 2 . PGE 2 , dbcAMP and 8‐ C pt‐ cAMP induced the phosphorylation of A kt, IκB kinase and IκBα and the translocation of p65 to the nucleus and increased NF ‐ κB dependent reporter gene activity, which was diminished by A kti. Conclusion and Implications Our findings suggest that PGE 2 induces ICAM ‐1 expression via EP4 receptor and E pac/ A kt/ NF ‐ κB signalling pathway in bEnd.3 brain endothelial cells, supporting its pathophysiological role in brain inflammation.