A luciferase-engineered cell line for study of cAMP regulation in endothelial cells

cAREL is a cAMP-responsive endothelial cell line carrying a luciferase reporter gene introduced by stable transfection of a luciferase enhancer trap into rabbit aortic endothelial cells. Luciferase gene expression in cAREL was stimulated 233-fold by 8-BrcAMP. Treatment with the beta-adrenoceptor agonist isoproterenol induced a 7.0-fold increase in luciferase expression, which was partially blocked by either beta(1)- or beta(2)-adrenoceptor antagonists and totally blocked by propranolol and by a combination of beta(1)- plus beta(2)-adrenoceptor antagonists. Receptor stimulation was mimicked by cholera toxin, forskolin, 8-BrcAMP, and isobutylmethylxanthine but not by 8-BrcGMP, dexamethasone, or phorbol 12-myristate 13-acetate. Stimulation by isoproterenol was completely blocked by H-89, a protein kinase A inhibitor. cAREL was also stimulated by A-23187, and this effect was abrogated by EGTA and H-89. cAREL is the first cAMP-sensitive endothelial cell line described, and it can be useful as a positive control, as a model for cAMP regulation, as a background to genetic introduction of receptors, as an indicator of intracellular pathway activation, and as a tool to investigate cAMP effects on other signaling pathways.