Resveratrol (RV), a polyphenolic substance found in grape skin, is proposed to account in part for the protective effect of red wine in the cardiovascular system. Angiotensin II (Ang II)-induced hypertrophy of vascular smooth muscle cells (VSMCs) is a pivotal step in the development of cardiovascular disease. The aims of this study were to test the hypothesis that RV may alter Ang II-mediated hypertrophic VSMC growth and to identify the putative underlying signaling pathways. We show that RV indeed potently inhibits Ang II-induced [ 3 H]leucine incorporation in a concentration-dependent manner (50 M RV, 71% inhibition). Western blot analysis reveals that phosphorylation of Akt/protein kinase B (PKB) and to a lesser extent the mitogen-activated protein kinase extracellular signal-regulated kinase (ERK) 1/2, both essentially involved in Ang II-mediated hypertrophy, is dose dependently reduced by RV. Consistent with these results, we show that RV attenuates phosphorylation of the p70 ribosomal protein S6 kinase (p70 S6K ), a kinase downstream of the ERK 1/2 as well as the Akt pathway, that is implicated in Ang II-induced protein synthesis. Upstream of Akt/PKB RV seems to mediate its antihypertrophic effect by inhibiting phosphorylation of the phosphatidylinositol 3-kinase (PI 3 K) rather than by activating phosphatases. In summary, we demonstrate for the first time that RV inhibits Ang II-induced VSMC hypertrophy, possibly by interfering mainly with the PI 3 K/Akt and p70 S6K but also with the ERK

Resveratrol (RV), a polyphenolic stilbene derivative, has been proposed to exert a plethora of beneficial cardiovascular effects. Of these, in particular, inhibition of vascular smooth muscle cell (VSMC) proliferation shows great promise for preventing cardiovascular disease. In the present study, we show that RV leads to a reversible arrest in early S phase of the VSMC cycle, accompanied by an accumulation of hyperphosphorylated retinoblastoma protein. In contrast to studies with other cell systems, RV decreases cellular levels of the cyclin-dependent kinase inhibitors p21Cip1 and p27 Kip1 . This is of particular interest because phosphorylated p53 protein (serine 15) is strongly enhanced by this substance. We further found that RV only slightly inhibits phosphorylation of Erk 1/2, protein kinase B/Akt, and p70 S6 kinase upon serum stimulation. Thus, inhibition of these kinases is not likely to contribute to the cell cycle effect of RV. Importantly, the observed S phase arrest is not linked to an increase in apoptotic cell death: there was no detectable increase in apoptotic nuclei and in levels of the proapoptotic protein Bax. This is the first study elucidating the molecular pathways mediating the antiproliferative properties of RV in VSMCs.

trans-Resveratrol (RV), a polyphenolic stilbene derivative found in grape skin and other food products, has been proposed to exert beneficial effects in cardiovascular disease. Our group has shown previously that RV inhibits angiotensin II (Ang II)-induced Akt activation and, consequently, vascular smooth muscle cell (VSMC) hypertrophy. In this work, to identify the molecular target of RV, we investigated the impact of RV on early signaling cascades in rat aortic VSMCs triggered by Ang II and epidermal growth factor (EGF). We show that RV does not influence Ang II-mediated transactivation of EGF-receptor but potently inhibits EGF-induced phosphorylation of Akt kinase, suggesting that RV acts downstream of EGF-receptor transactivation in VSMCs. Recent evidence indicates that the adapter molecule Gab1, together with the protein tyrosine phosphatase Shp2, is critically involved in regulating the strength and duration of phosphatidylinositol-3-kinase (PI3K) and Akt activation upon EGF stimulation in fibroblasts. Our results show that stimulation of VSMCs with EGF as well as Ang II leads to a rapid tyrosine phosphorylation of Gab1 and its association with the p85 subunit of PI3K. RV attenuates these processes. Experiments performed in Shp2-deficient fibroblasts revealed that RV does not inhibit EGF-stimulated Akt activation in these cells, suggesting that Shp2 is necessary for the inhibitory effect of RV on the PI3K/Akt pathway. Furthermore, RV treatment activates Shp2. We therefore propose that RV blocks Akt activation in Ang II-and EGF-stimulated VSMCs by activating Shp2, thus preventing interaction between Gab1 and PI3K that is necessary for further signal transduction.