Redox Deficient Cysteine Residues Impair β2‐Adrenergic Receptor Function

Inhaled β 2 ‐adrenergic receptor (β 2 AR) agonists are clinically used to elicit rapid bronchial dilation, primarily for the treatment of asthma attacks. Asthmatic tissue is characterized by high levels of reactive oxygen species (ROS), over‐expression of the ROS generating enzyme NADPH oxidase, and reduced expression of the ROS metabolizing enzyme superoxide dismutase 2. However, most pharmacological data on the β 2 AR has been derived from receptor evaluation in a non‐oxidative environment, which fails to address the potential impact ROS may have on the β 2 AR itself. Cysteine residues of the β 2 AR undergo transient first order oxidation, a functionally significant post translational modification known as cysteine‐S‐sulfenation. Despite the vast literature explaining the physiology of β 2 AR and the known interplay between β 2 AR and ROS, the actual impact of ROS on β 2 AR has thus far been overlooked. HEK293 cells overexpressing β 2 AR and CALU3 endogenously expressing β 2 AR were utilized in these studies. Redox dependent β 2 AR alterations in ligand binding were evaluated with membrane and whole cell preparations by utilizing tritiated alprenolol. Functional G protein signaling was examined with the use of a cAMP. Functional G protein independent signaling was looked at via confocal microscopy and receptor internalization. Receptor oxidation increases ligand binding, an effect reversed in redox deficient receptors. Redox deficient receptors have a diminished G protein signaling cascade, reduced agonist mediated β‐arrestin recruitment and a blunted internalization response. This research is the first to address β 2 AR function based on oxidation state, which implicates altered physiology dependent upon redox state. Given asthmatic tissue has elevated ROS levels and β 2 AR agonists are clinically utilized for the treatment of asthmatic attacks, our findings provide evidence that β 2 AR function in an oxidizing environment may be different from the physiology described in current literature. Furthermore, this research highlights the effects of a novel post translation modification on one of the most well understood GPCRs, further indicating we may still have much to learn about β 2 AR function and physiology. Support or Funding Information This work was funded by the NIH/NHLBI grant HL138603 to NHM. This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .