Role of Gi/o-Src kinase-PI3K/Akt pathway and caveolin-1 in β2-adrenoceptor coupling to endothelial NO synthase in mouse pulmonary artery

Sebastien Banquet, Estelle Delannoy , Abdelali Agouni, Chantal Dessy , Sabrina Lacomme , Fabien Hubert, Vincent Richard , Bernard Muller , Véronique Leblais

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44 Citations (Scopus)


Activation of the β2-adrenoceptor (β2-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 β2-AR-mediated eNOS activation, with special focus on Gi/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 β2-AR agonist procaterol was reduced by inhibitors of Gi/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-β-cyclodextrin). Procaterol induced eNOS phosphorylation at Ser1177, which was prevented by PTX, PP2 or Akt inhibitor. Procaterol also promoted caveolin-1 phosphorylation at Tyr14, 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-β-cyclodextrin or caveolin-1 gene deletion. To conclude, the mouse pulmonary endothelial β2-AR is coupled to a Gi/o-Src kinase-PI3K/Akt pathway to promote eNOS phosphorylation at Ser1177 leading to a NO-dependent vasorelaxation. Caveolin-1 exerts a negative control on this response that is abrogated by its phosphorylation at Tyr14, through a Gi/o-Src kinase pathway. Since pulmonary β2-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.
Original languageEnglish
Pages (from-to)1136-1143
Number of pages8
JournalCellular Signalling
Issue number7
Early online date6 Mar 2011
Publication statusPublished - 23 Jul 2011

Bibliographical note

The authors would like to thank Mrs. M. Lacayrerie for excellent animal care, Dr. MC. Martínez (UMR INSERM 771-CNRS6214, Angers, France) for providing assistance with Western blotting experiments, Mrs. F. Lefebvre (UMR-S 769, Châtenay-Malabry, France) and Mrs. V. Domergue-Dupont (IFR141, Châtenay-Malabry, France) for assistance in animal care and Dr. R. Fischmeister (UMR-S 769, Châtenay-Malabry, France) for critical reading of the manuscript.

This work was partially supported by the “Fondation de France” [grants 2006005603, 2008002719]; and the “Agence Nationale de la Recherche” [grant ANR06 Physio 015 01]. The authors thank the “Association des Enseignants de Pharmacologie des Facultés de Pharmacie” for partially supporting the collaboration between Unit of Pharmacology and Therapeutics (Brussels) and INSERM U1045 (Bordeaux).


  • pulmonary artery
  • endothelium
  • β2-adrenoceptor
  • nitric oxide
  • caveolin


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