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Ligand Binding to the β2‐Adrenergic Receptor is Dependent Upon its Oxidation State
Author(s) -
Rambacher Kalyn M.,
Moniri Nader H.
Publication year - 2018
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2018.32.1_supplement.555.14
Subject(s) - chemistry , sulfenic acid , ligand (biochemistry) , cysteine , receptor , nadph oxidase , intracellular , biochemistry , biophysics , reactive oxygen species , microbiology and biotechnology , biology , enzyme
Inhaled β 2 ‐adrenergic receptor (β 2 AR) agonists are the gold standard treatment of an acute asthma attack and function by eliciting rapid bronchial dilation. Asthmatic tissue is characterized by increased expression of NADPH Oxidase (NOX) and subsequent increased levels of reactive oxygen species (ROS) compared to healthy tissue. We and others have previously showed that agonism of β 2 AR with ‐isoproterenol (ISO) leads to activation of NOX, and generation of intracellular ROS. We have also previously shown that these ROS are capable of oxidizing cysteine residues on the β 2 AR itself, a process known as cysteine‐S‐sulfenation. Emerging evidence has established cysteine‐S‐sulfenation as a functionally significant post translational protein modification, which thus far has not been evaluated for its effects on β 2 AR ligand binding. Utilizing isolated plasma membrane and whole cell radioligand binding, the current study evaluates oxidation state‐dependent alterations to ligand binding to the β 2 AR in HEK293 cells over‐expressing β 2 AR and in immortalized human lung epithelial cells. Specific ligand binding is significantly increased in the oxidized receptor state in both cell lines and in both membrane and whole cell assays. This effect is reversed by receptor labeling with the sulfenic acid selective small molecule dimedone, indicating increased ligand binding is specific to the presence of cysteine sulfenic acids on the β 2 AR. Furthermore, isoproterenol can fully displace radioligand binding in all redox states to the same extent in a monophasic manner, indicating redox state either directly or indirectly modifies the β 2 AR's orthosteric binding pocket. Given the oxidative environment native to asthmatic tissue, the findings presented here have implications for asthma treatment with β 2 AR agonists, and present a need to better understand how β 2 AR may interact differently with ligands in asthmatic tissue compared to healthy models. Support or Funding Information This work was funded by the NIH/NHLBI grant HL138603 to NHM. This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .