Inactivation of adenosine A2A receptor attenuates basal and angiotensin II-induced ROS production by Nox2 in endothelial cells

Abstract

Endothelial cells (ECs) express a Nox2 enzyme, which, by generating reactive oxygen species (ROS), contributes to EC redox signaling and angiotensin II (AngII)-induced endothelial dysfunction. ECs also express abundantly an adenosine A2A receptor (A2AR), but its role in EC ROS production remains unknown. In this study, we investigated the role of A 2AR in the regulation of Nox2 activity and signaling in ECs with or without acute AngII stimulation. In cultured ECs (SVEC4-10), AngII (100 nM, 30 min) significantly increased Nox2 membrane translocation and association with A2AR. These were accompanied by p47phox, ERK1/2, p38 MAPK, and Akt phosphorylation and an increased ROS production (169 ± 0.04%). These AngII effects were inhibited back to the control levels by a specific A2AR antagonist (SCH58261), or adenosine deaminase, or by knockdown of A2AR or Nox2 using specific siRNAs. Knockdown of A2AR, as determined by Western blotting, decreased Nox2 and p47phox expression. In wild-type mouse aorta, SCH58261 significantly reduced acute AngII-induced ROS production and preserved endothelium-dependent vessel relaxation to acetylcholine. These results were further confirmed by using aortas from A2AR knock-out mice. In conclusion, A2AR is involved in the regulation of EC ROS production by Nox2. Inhibition or blockade of A2AR protects ECs from acute AngII-induced oxidative stress, MAPK activation, and endothelium dysfunction. © 2010 by The American Society for Biochemistry and Molecular Biology, Inc.