Resveratrol blocks Akt activation in angiotensin II- or EGF-stimulated vascular smooth muscle cells in a redox-independent manner.
OBJECTIVE
Resveratrol (RV), an antioxidant, inhibits angiotensin II (Ang II)-induced hypertrophy and Ang II- or epidermal growth factor (EGF)-induced Akt phosphorylation in rat vascular smooth muscle cells (VSMCs). Both signalling pathways are reported to utilize reactive oxygen species (ROS). The aim of this study was to show whether RV reduces the ROS level in Ang II- or EGF-activated VSMCs and whether reduction of ROS causes the impeded signalling towards Akt in the presence of RV.


RESULTS
We show here that RV reduces intracellular ROS and extracellular H₂O₂ release from VSMCs as measured using 2',7'-dichlorodihydrofluorescein-diacetate and Amplex Red™. Since NADPH oxidases (Nox) 1 and 4 are major ROS sources in VSMCs, we examined their need for Akt phosphorylation in response to Ang II or EGF. Experiments using the blocking peptide gp91ds-tat verified a role for Nox1 in Ang II signalling towards Akt, but excluded a role for Nox1 in the respective EGF signalling. A small interfering RNA-mediated knock-down of Nox4 showed that Nox4 was not required for Ang II- or EGF-induced Akt phosphorylation. Use of the flavoprotein inhibitor diphenyleneiodonium, N-acetyl-cysteine, and non-antioxidant RV derivatives revealed that the antioxidant capacity of RV is not required for the inhibition of Akt phosphorylation, in both rat and human VSMCs.


CONCLUSIONS
Thus, although RV acts as an antioxidant, the antihypertrophic response of RV in VSMCs and the signalling downstream of the EGF receptor towards Akt seem to be largely redox independent.
Department of Pharmacognosy, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria.
Cornelia E
CE
Schreiner
Mario
M
Kumerz
Julia
J
Gesslbauer
Daniel
D
Schachner
Helge
H
Joa
Thomas
T
Erker
Atanas G
AG
Atanasov
Elke H
EH
Heiss
Verena M
VM
Dirsch
D000704:Analysis of Variance; D000804:Angiotensin II / Q000378:metabolism*; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D048430:Cell Shape / Q000187:drug effects; D002478:Cells, Cultured; D004789:Enzyme Activation; D004815:Epidermal Growth Factor / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000378:metabolism; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000201:enzymology / Q000473:pathology; D032389:Myocytes, Smooth Muscle / Q000187:drug effects* / Q000201:enzymology / Q000473:pathology; D009247:NADH, NADPH Oxidoreductases / Q000378:metabolism; D000074624:NADPH Oxidase 1; D000074663:NADPH Oxidase 4; D019255:NADPH Oxidases / Q000235:genetics / Q000378:metabolism; D010084:Oxidation-Reduction; D010766:Phosphorylation; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D034622:RNA Interference; D051381:Rats; D017207:Rats, Sprague-Dawley; D000077185:Resveratrol; D015398:Signal Transduction / Q000187:drug effects; D013267:Stilbenes / Q000494:pharmacology*; D013997:Time Factors; D014162:Transfection
D000975:Antioxidants; D013267:Stilbenes; D000804:Angiotensin II; D004815:Epidermal Growth Factor; D006861:Hydrogen Peroxide; D009247:NADH, NADPH Oxidoreductases; D000074624:NADPH Oxidase 1; D000074663:NADPH Oxidase 4; D019255:NADPH Oxidases; C000614712:NOX1 protein, rat; C498911:Nox4 protein, rat; D051057:Proto-Oncogene Proteins c-akt; D000077185:Resveratrol