Rapid transactivation of the vascular endothelial growth factor receptor KDR/Flk-1 by the bradykinin B2 receptor contributes to endothelial nitric-oxide synthase activation in cardiac capillary endothelial cells.
Bradykinin (BK) and vascular endothelial growth factor (VEGF)-165 stimulate vasodilatation, microvascular permeability, and angiogenesis via the activation of the B2-type and KDR/Flk-1 receptors. To delineate the signal transduction pathways distal to the receptor activation in microvascular permeability, we compared their effects on two downstream targets, i.e. endothelial nitric-oxide (NO) synthase (eNOS) and F-actin, in primary cultures of cardiac capillary endothelial cells. The two mediators induced a similar cytoskeletal reorganization and both the translocation and activation of eNOS, leading to NO release within the first minutes of cell exposure. At the same time, BK produced the tyrosine phosphorylation and internalization of KDR/Flk-1 as did VEGF itself. This transactivation was blocked by the selective inhibitor of VEGF receptor tyrosine kinase activity but not by inhibitors of epidermal growth factor receptor or protein kinase C activity. The selective inhibitor of VEGF receptor tyrosine kinase activity totally prevented the effects of VEGF but only partially inhibited NO release induced by BK without affecting the concomitant cytoskeletal reorganization. Thus, BK transactivated KDR/Flk-1 through an intrinsic kinase activity of KDR/Flk-1, resulting in a further eNOS activation in endothelial cells. This represents a novel mechanism whereby a G protein-coupled receptor activates a receptor tyrosine kinase to generate biological response.
Thuringer
Dominique
D
Institut de Pharmacologie Moléculaire et Cellulaire, CNRS Unité Mixte de Recherche 6097, 660 route des Lucioles, Sophia-Antipolis, 06560 Valbonne, France. thuringer@ipmc.cnrs.fr
Maulon
Laurence
L
Frelin
Christian
C
D000818:Animals; D002196:Capillaries / Q000201:enzymology*; D002478:Cells, Cultured; D003331:Coronary Vessels / Q000201:enzymology*; D017077:Culture Media, Conditioned; D004789:Enzyme Activation; D019001:Nitric Oxide Synthase / Q000378:metabolism*; D052250:Nitric Oxide Synthase Type III; D011493:Protein Kinase C / Q000378:metabolism; D021381:Protein Transport; D011518:Proto-Oncogene Proteins / Q000235:genetics*; D051381:Rats; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics*; D043782:Receptor, Bradykinin B2; D018002:Receptors, Bradykinin / Q000502:physiology*; D015533:Transcriptional Activation / Q000502:physiology*; D040281:Vascular Endothelial Growth Factor Receptor-1
D017077:Culture Media, Conditioned; D011518:Proto-Oncogene Proteins; D043782:Receptor, Bradykinin B2; D018002:Receptors, Bradykinin; D019001:Nitric Oxide Synthase; D052250:Nitric Oxide Synthase Type III; C496316:Nos3 protein, rat; D020794:Receptor Protein-Tyrosine Kinases; D040281:Vascular Endothelial Growth Factor Receptor-1; D011493:Protein Kinase C