The antiinflammatory effect of laminar flow: the role of PPARgamma, epoxyeicosatrienoic acids, and soluble epoxide hydrolase.
We previously reported that laminar flow activates peroxisome proliferator-activated receptor gamma (PPARgamma) in vascular endothelial cells in a ligand-dependent manner that involves phospholipase A2 and cytochrome P450 epoxygenases. In this study, we investigated whether epoxyeicosatrienoic acids (EETs), the catalytic products of cytochrome P450 epoxygenases, are PPARgamma ligands. Competition and direct binding assays revealed that EETs bind to the ligand-binding domain of PPARgamma with K(d) in the microM range. In the presence of adamantyl-ureido-dodecanoic acid (AUDA), a soluble epoxide hydrolase (sEH)-specific inhibitor, EETs increased PPARgamma transcription activity in endothelial cells and 3T3-L1 preadipocytes. Inclusion of AUDA in the perfusing media enhanced, but overexpression of sEH reduced, the laminar flow-induced PPARgamma activity. Furthermore, laminar flow augmented cellular levels of EETs but decreased sEH at the levels of mRNA, protein, and activity. Blocking PPARgamma by GW9662 abolished the EET/AUDA-mediated antiinflammatory effect, which indicates that PPARgamma is an effector of EETs.
Liu
Yi
Y
Division of Biomedical Sciences, University of California, Riverside, CA 92521, USA.
Zhang
Yingjia
Y
Schmelzer
Kara
K
Lee
Tzong-Shyuan
TS
Fang
Xiang
X
Zhu
Yi
Y
Spector
Arthur A
AA
Gill
Sarjeet
S
Morisseau
Christophe
C
Hammock
Bruce D
BD
Shyy
John Y-J
JY
D041721:3T3-L1 Cells; D000818:Animals; D001483:Base Sequence; D002384:Catalysis; D002417:Cattle; D002478:Cells, Cultured; D017931:DNA Primers; D015536:Down-Regulation; D015777:Eicosanoids / Q000502:physiology*; D004851:Epoxide Hydrolases / Q000502:physiology*; D007249:Inflammation / Q000503:physiopathology*; D051379:Mice; D047495:PPAR gamma / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012995:Solubility
D017931:DNA Primers; D015777:Eicosanoids; D047495:PPAR gamma; D004851:Epoxide Hydrolases