Ciccarelli Michele, Cipolletta Ersilia, Santulli Gaetano, Campanile Alfonso, Pumiglia Kevin, Cervero Pasquale, Pastore Lucio, Astone Dalila, Trimarco Bruno, Iaccarino Guido
Department of Clinical Medicine, Cardiovascular and Immunological Sciences, Federico II University, Naples, Italy.
Cell Signal. 2007 Sep;19(9):1949-55. doi: 10.1016/j.cellsig.2007.05.007. Epub 2007 May 29.
We have recently demonstrated that endothelial beta(2) adrenergic receptors (beta(2)AR) regulate eNOS activity and consequently vascular tone, through means of PKB/AKT. In this work we explored the signal transduction pathway leading to AKT/eNOS activation in endothelial cells (EC). Using pharmacological and molecular inhibitors both in cultured EC cells and in ex vivo rat carotid preparations, we found that G(i) coupling of the beta(2)AR is needed for AKT activation and vasorelaxation. Since endothelial activation is sensitive to pertussis toxin but not to G(ibetagamma) inhibition by betaARKct, we conclude that G(alphai) mediates betaAR induced AKT activation. Downstream, betaAR signalling requires the soluble tyrosine kinase SRC, as both in cultured EC and rat carotid, the mutant dominant negative of SRC prevent beta(2)AR induced endothelial activation and vasodilation. In EC, G(alphai) directly interacts with SRC and this interaction leads to SRC activation and phosphorylation in a manner that is regulated by beta(2)AR stimulation. We propose a novel signal transduction pathway for beta(2)AR stimulation trough G(alphai) and SRC, leading to activation of AKT.
我们最近证实，内皮细胞β₂肾上腺素能受体（β₂AR）通过蛋白激酶B/蛋白激酶B（PKB/AKT）调节内皮型一氧化氮合酶（eNOS）的活性，进而调节血管张力。在这项研究中，我们探索了内皮细胞（EC）中导致AKT/eNOS激活的信号转导途径。在培养的EC细胞和离体大鼠颈动脉标本中使用药理学和分子抑制剂，我们发现β₂AR的G(i)偶联是AKT激活和血管舒张所必需的。由于内皮细胞激活对百日咳毒素敏感，但对βARKct抑制G(ibetagamma)不敏感，我们得出结论，G(alphai)介导βAR诱导的AKT激活。在下游，βAR信号传导需要可溶性酪氨酸激酶SRC，因为在培养的EC细胞和大鼠颈动脉中，SRC的突变显性阴性均能阻止β₂AR诱导的内皮细胞激活和血管舒张。在EC细胞中，G(alphai)直接与SRC相互作用，这种相互作用导致SRC以受β₂AR刺激调节的方式激活和磷酸化。我们提出了一条通过G(alphai)和SRC刺激β₂AR的新信号转导途径，导致AKT激活。
