Stimulation of the mitogen-activated protein kinase via the A2A-adenosine receptor in primary human endothelial cells

J Biol Chem. 1997 Feb 28;272(9):5792-9. doi: 10.1074/jbc.272.9.5792.


Adenosine exerts a mitogenic effect on human endothelial cells via stimulation of the A2A-adenosine receptor. This effect can also be elicited by the beta2-adrenergic receptor but is not mimicked by elevation of intracellular cAMP levels. In the present work, we report that stimulation of the A2A-adenosine receptor and of the beta2-adrenergic receptor activates mitogen-activated protein kinase (MAP kinase) in human endothelial cells based on the following criteria: adenosine analogues and beta-adrenergic agonists cause an (i) increase in tyrosine phosphorylation of the p42 isoform and to a lesser extent of the p44 isoform of MAP kinase and (ii) stimulate the phosphorylation of myelin basic protein by MAP kinase; (iii) this is accompanied by a redistribution of the enzyme to the perinuclear region. Pretreatment of the cells with cholera toxin (to down-regulate Gsalpha) abolishes activation of MAP kinase by isoproterenol but not that induced by adenosine analogues. In addition, MAP kinase stimulation via the A2A-adenosine receptor is neither impaired following pretreatment of the cells with pertussis toxin (to block Gi-dependent pathways) nor affected by GF109203X (1 microM; to inhibit typical protein kinase C isoforms) nor by a monoclonal antibody, which blocks epidermal growth factor-dependent signaling. In contrast, MAP kinase activation is blocked by PD 098059, an inhibitor of MAP kinase kinase 1 (MEK1) activation, which also blunts the A2A-adenosine receptor-mediated increase in [3H]thymidine incorporation. Activation of the A2A-adenosine receptor is associated with increased levels of GTP-bound p21(ras). Thus, our experiments define stimulation of MAP kinase as the candidate cellular target mediating the mitogenic action of the A2A-adenosine receptor on primary human endothelial cells; the signaling pathway operates via p21(ras) and MEK1 but is independent of Gi, Gs, and the typical protein kinase C isoforms. This implies an additional G protein which links this prototypical Gs-coupled receptor to the MAP kinase cascade.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 8-Bromo Cyclic Adenosine Monophosphate / pharmacology
  • Adenosine / analogs & derivatives
  • Adenosine / pharmacology
  • Adenosine-5'-(N-ethylcarboxamide)
  • Antibodies, Monoclonal
  • Calcium-Calmodulin-Dependent Protein Kinases / metabolism*
  • Endothelium, Vascular / enzymology*
  • Enzyme Activation
  • Enzyme Inhibitors / pharmacology
  • Epidermal Growth Factor / pharmacology
  • ErbB Receptors / immunology
  • Fibroblast Growth Factor 2 / pharmacology
  • Flavonoids / pharmacology
  • GTP-Binding Proteins / metabolism
  • Humans
  • Isoproterenol / pharmacology
  • Phosphorylation
  • Receptors, Purinergic P1 / metabolism*
  • Thymidine / metabolism
  • Tyrosine / metabolism
  • Vasodilator Agents / pharmacology*


  • Antibodies, Monoclonal
  • Enzyme Inhibitors
  • Flavonoids
  • Receptors, Purinergic P1
  • Vasodilator Agents
  • Fibroblast Growth Factor 2
  • 8-Bromo Cyclic Adenosine Monophosphate
  • Adenosine-5'-(N-ethylcarboxamide)
  • Tyrosine
  • Epidermal Growth Factor
  • ErbB Receptors
  • Calcium-Calmodulin-Dependent Protein Kinases
  • GTP-Binding Proteins
  • Adenosine
  • Isoproterenol
  • 2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one
  • Thymidine