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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 A(2A) receptor (A(2A)R), but its role in EC ROS production remains unknown. In this study, we investigated the role of A(2A)R 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 A(2A)R. These were accompanied by p47(phox), 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 A(2A)R antagonist (SCH58261), or adenosine deaminase, or by knockdown of A(2A)R or Nox2 using specific siRNAs. Knockdown of A(2A)R, as determined by Western blotting, decreased Nox2 and p47(phox) 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 A(2A)R knock-out mice. In conclusion, A(2A)R is involved in the regulation of EC ROS production by Nox2. Inhibition or blockade of A(2A)R protects ECs from acute AngII-induced oxidative stress, MAPK activation, and endothelium dysfunction.

SUBMITTER: Thakur S

PROVIDER: S-EPMC3000993 | biostudies-literature | 2010 Dec

REPOSITORIES: biostudies-literature

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

Thakur Sapna S Du Junjie J Hourani Susanna S Ledent Catherine C Li Jian-Mei JM

The Journal of biological chemistry 20101012 51

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 A(2A) receptor (A(2A)R), but its role in EC ROS production remains unknown. In this study, we investigated the role of A(2A)R in the regulation of Nox2 activity and signaling in ECs with or without acute AngII stimulation. In cultured ECs (SVEC4-10), AngII (100 nm, ...[more]

PMID: 20940302

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Project description:AimsAngiotensin II (AngII)-induced superoxide (O2(•-)) production by the NADPH oxidases and mitochondria has been implicated in the pathogenesis of endothelial dysfunction and hypertension. In this work, we investigated the specific molecular mechanisms responsible for the stimulation of mitochondrial O2(•-) and its downstream targets using cultured human aortic endothelial cells and a mouse model of AngII-induced hypertension.ResultsWestern blot analysis showed that Nox2 and Nox4 were present in the cytoplasm but not in the mitochondria. Depletion of Nox2, but not Nox1, Nox4, or Nox5, using siRNA inhibits AngII-induced O2(•-) production in both mitochondria and cytoplasm. Nox2 depletion in gp91phox knockout mice inhibited AngII-induced cellular and mitochondrial O2(•-) and attenuated hypertension. Inhibition of mitochondrial reverse electron transfer with malonate, malate, or rotenone attenuated AngII-induced cytoplasmic and mitochondrial O2(•-) production. Inhibition of the mitochondrial ATP-sensitive potassium channel (mitoK(+)ATP) with 5-hydroxydecanoic acid or specific PKCɛ peptide antagonist (EAVSLKPT) reduced AngII-induced H2O2 in isolated mitochondria and diminished cytoplasmic O2(•-). The mitoK(+)ATP agonist diazoxide increased mitochondrial O2(•-), cytoplasmic c-Src phosphorylation and cytoplasmic O2(•-) suggesting feed-forward regulation of cellular O2(•-) by mitochondrial reactive oxygen species (ROS). Treatment of AngII-infused mice with malate reduced blood pressure and enhanced the antihypertensive effect of mitoTEMPO. Mitochondria-targeted H2O2 scavenger mitoEbselen attenuated redox-dependent c-Src and inhibited AngII-induced cellular O2(•-), diminished aortic H2O2, and reduced blood pressure in hypertensive mice.Innovation and conclusionsThese studies show that Nox2 stimulates mitochondrial ROS by activating reverse electron transfer and both mitochondrial O2(•-) and reverse electron transfer may represent new pharmacological targets for the treatment of hypertension.

Dataset Information

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

Publications

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

Similar Datasets

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