title: Agonist-stimulated reactive oxygen species formation regulates beta2-adrenergic receptor signal transduction.
abstract: Generation of reactive oxygen species (ROS) can occur upon agonist stimulation of surface receptors to modulate downstream signaling processes. Here, we show that activation of the beta2 adrenergic receptor (beta2AR) by stimulation with the agonist isoproterenol leads to generation of ROS that is required for beta2AR signal transduction. Specifically, we show that inhibition of NADPH oxidase with diphenyliodonium chloride, inhibition of the small GTPase Rac1 with NSC23766, and inhibition of formed ROS with the antioxidant N-acetyl-L-cysteine decreases beta2AR-mediated cAMP formation, protein kinase A activation, and receptor phosphorylation and internalization, but does not impact ligand binding. The results also show that inhibition of ROS attenuates active beta2AR-mediated binding of GTP to alpha subunits of heterotrimeric G proteins. Based on these results, we propose that agonist-dependent ROS formation is needed for beta2AR signal transduction, perhaps through stabilization of active receptor conformers by redox-mediated modification of receptor and/or Galpha proteins cysteine residues.
authors: Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, Mercer University, 3001 Mercer University Drive, Atlanta, GA 30341, United States. Moniri_nh@mercer.edu <Moniri_nh@mercer.edu>
authors: Nader H
authors: NH
authors: Moniri
authors: Yehia
authors: Y
authors: Daaka
mesh_terms: D000111:Acetylcysteine / Q000494:pharmacology; D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D000634:Aminoquinolines / Q000494:pharmacology; D001713:Biphenyl Compounds / Q000494:pharmacology; D002460:Cell Line; D000242:Cyclic AMP / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004705:Endocytosis / Q000187:drug effects / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D019204:GTP-Binding Proteins / Q000378:metabolism; D006801:Humans; D007545:Isoproterenol / Q000494:pharmacology*; D007668:Kidney / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D009861:Onium Compounds / Q000494:pharmacology; D010766:Phosphorylation; D011743:Pyrimidines / Q000494:pharmacology; D017382:Reactive Oxygen Species / Q000378:metabolism*; D018343:Receptors, Adrenergic, beta-2 / Q000187:drug effects* / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*
chemical_list: D000318:Adrenergic beta-Agonists; D000634:Aminoquinolines; D001713:Biphenyl Compounds; D004791:Enzyme Inhibitors; C487513:NSC 23766; D009861:Onium Compounds; D011743:Pyrimidines; D017382:Reactive Oxygen Species; D018343:Receptors, Adrenergic, beta-2; C031291:diphenyliodonium; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D019204:GTP-Binding Proteins; D007545:Isoproterenol; D000111:Acetylcysteine