Titre du document / Document title

Activation of endothelial nitric-oxide synthase by the p38 MAPK in response to black tea polyphenols

Auteur(s) / Author(s)

ANTER Elad ; THOMAS Shane R. ; SCHULZ Eberhard ; SHAPIRA Oz M. ; VITA Joseph A. ; KEANEY John F. ;

Résumé / Abstract

Black tea improves endothelial function in patients with coronary artery disease. We sought to determine the responsible components of black tea and elucidate the underlying cell signaling mechanisms. We exposed porcine aortic endothelial cells to components of black tea and found that the polyphenol fraction acutely enhanced nitric oxide bioactivity. This effect involved endothelial nitric-oxide synthase (eNOS) phosphorylation at Ser-1177 and dephosphorylation at Thr-495, consistent with increased eNOS activity. These effects were calcium-dependent, as removal of extracellular calcium prevented eNOS phosphorylation at Ser-1177, whereas inhibition of intracellular calcium mobilization with TMB-8 blunted Thr-495 dephosphorylation. Black tea polyphenol-induced eNOS activation appeared dependent upon the phosphatidylinositol 3-kinase-Akt pathway, as it was significantly inhibited by LY294002 and a dominant negative Akt, respectively. Pharmacological inhibition of p38 mitogen-activated protein kinase (p38 MAPK) with either SB202190 or SB203580 as well as overexpression of a dominant negative p38 MAPKa attenuated both eNOS activation and phosphorylation changes in response to black tea polyphenols. Inhibition of p38 MAPKa also blunted Akt activation in response to black tea polyphenols, suggesting that p38a MAPK is upstream of Akt in this pathway. Finally, a constitutively active mutant of MKK6bE, an upstream kinase for p38 MAPK, enhanced both the basal and stimulated activity of Akt, leading to increased eNOS activity. Taken together, these data identify the p38 MAPK as an upstream component of Akt-mediated eNOS activation.

Revue / Journal Title

The Journal of biological chemistry   ISSN 0021-9258   CODEN JBCHA3 

Source / Source

2004, vol. 279, n^o45, pp. 46637-46643 [7 page(s) (article)]

Langue / Language

Anglais

Editeur / Publisher

American Society for Biochemistry and Molecular Biology, Bethesda, MD, ETATS-UNIS  (1905) (Revue)

Localisation / Location

INIST-CNRS, Cote INIST : 3082, 35400012255551.0380