Endothelial beta2 adrenergic signaling to AKT: role of Gi and SRC.
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.
Ciccarelli
Michele
M
Department of Clinical Medicine, Cardiovascular and Immunological Sciences, Federico II University, Naples, Italy.
Cipolletta
Ersilia
E
Santulli
Gaetano
G
Campanile
Alfonso
A
Pumiglia
Kevin
K
Cervero
Pasquale
P
Pastore
Lucio
L
Astone
Dalila
D
Trimarco
Bruno
B
Iaccarino
Guido
G
D000256:Adenoviridae; D000818:Animals; D042783:Endothelial Cells / Q000166:cytology / Q000201:enzymology*; D004730:Endothelium, Vascular / Q000166:cytology / Q000201:enzymology; D004789:Enzyme Activation; D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000378:metabolism*; D066298:In Vitro Techniques; D010455:Peptides / Q000378:metabolism; D011485:Protein Binding; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D016392:Proto-Oncogene Proteins pp60(c-src) / Q000378:metabolism*; D051381:Rats; D011921:Rats, Inbred WKY; D018343:Receptors, Adrenergic, beta-2 / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D015398:Signal Transduction; D014161:Transduction, Genetic
D010455:Peptides; D018343:Receptors, Adrenergic, beta-2; D011994:Recombinant Proteins; C445259:beta-adrenergic receptor kinase inhibitory peptide; D016392:Proto-Oncogene Proteins pp60(c-src); D051057:Proto-Oncogene Proteins c-akt; D019206:GTP-Binding Protein alpha Subunits, Gi-Go