Journal
CELLULAR SIGNALLING
Volume 23, Issue 7, Pages 1136-1143Publisher
ELSEVIER SCIENCE INC
DOI: 10.1016/j.cellsig.2011.02.008
Keywords
Pulmonary artery; Endothelium; beta(2)-adrenoceptor; Nitric oxide synthase; Caveolin
Categories
Funding
- Fondation de France [2006005603, 20080027191]
- Agence Nationale de la Recherche [ANR06 Physio 015 01]
- Association des Enseignants de Pharmacologie des Facultes de Pharmacie
- Unit of Pharmacology and Therapeutics (Brussels)
- INSERM (Bordeaux) [U1045]
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Activation of the beta(2)-adrenoceptor (beta(2)-AR) elicits an endothelial nitric oxide synthase (eNOS)-dependent relaxation in mouse pulmonary artery, which, contrary to the muscarinic receptor-dependent relaxation, is preserved in hypoxic pulmonary arterial hypertension. We therefore characterized the signaling pathways underlying the beta(2)-AR-mediated eNOS activation, with special focus on G(i/o) proteins, protein kinases and caveolae. Functional studies (for evaluation of vasorelaxant response), Western blotting (for assessment of eNOS and caveolin-1 phosphorylation) and transmission electron microscopy (for visualization of caveolae) were conducted in pulmonary arteries from wild-type or caveolin-1 knockout mice. In wild-type isolated arteries, relaxation to the selective beta(2)-AR agonist procaterol was reduced by inhibitors of G(i/o) proteins (pertussis toxin, PTX), phosphatidylinositol 3-kinase (PI3K; wortmannin or LY 294002), Akt (Akt inhibitor X) and Src-kinase (PP2) and by cholesterol depletion (using methyl-beta-cyclodextrin). Procaterol induced eNOS phosphorylation at Ser(1177), which was prevented by PTX, PP2 or Akt inhibitor. Procaterol also promoted caveolin-1 phosphorylation at Tyr(14), which was decreased by PTX or PP2. Caveolin-1 gene deletion resulted in endothelial caveolae disruption in mouse pulmonary artery and in potentiation of procaterol-induced relaxation. Unlike procaterol, acetylcholine-induced relaxation was unaffected by PTX, methyl-beta-cyclodextrin or caveolin-1 gene deletion. To conclude, the mouse pulmonary endothelial beta(2)-AR is coupled to a G(i/o)-Src kinase-PI3K/Akt pathway to promote eNOS phosphorylation at Ser(1177) leading to a NO-dependent vasorelaxation. Caveolin-1 exerts a negative control on this response that is abrogated by its phosphorylation at Tyr(14), through a G(i/o)-Src kinase pathway. Since pulmonary beta(2)-AR- and muscarinic receptor-mediated relaxations differentiate in their respective signaling pathways leading to eNOS activation and sensitivities during hypoxia-induced pulmonary arterial hypertension, mechanisms underlying eNOS activation might be key determinants of pulmonary endothelial dysfunction. (C) 2011 Elsevier Inc. All rights reserved.
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