12/15-Lipoxygenase-Dependent ROS Production Is Required For Diet-Induced Endothelial Barrier Dysfunction

To understand the mechanisms of 15(S)-hydroxyeicosatetraenoic acid (15(S)-HETE)-induced endothelial cell (EC) barrier dysfunction, we examined the role of xanthine oxidase (XO). 15(S)-HETE induced JamA phosphorylation on Y164, Y218 and Y280 involving XO-mediated ROS production and Src and Pyk2 activation, resulting in its dissociation from occludin, thereby causing tight junction disruption, increased vascular permeability and enhanced leukocyte and monocyte transmigration in vitro using EC monolayer and ex vivo using arteries as models. The phosphorylation of JamA on Y164, Y218, and Y280 appear to be critical for its role in 15(S)-HETE-induced EC barrier dysfunction, as mutation of any one of these amino acid residues prevented its dissociation from occludin and restored TJ integrity and barrier function. In response to high-fat diet (HFD) feeding, WT but not 12/15-LO-/- mice showed enhanced XO expression and its activity in the artery, which was correlated with increased aortic TJ disruption and barrier...