Cysteine redox state regulates human β2-adrenergic receptor binding and function.

Airway diseases like asthma involve elevated reactive oxygen species (ROS) levels. β2-adrenergic receptor (β2AR) agonists are commonly used to treat asthma. Earlier findings suggest that β2AR function is linked to ROS production. These ROS oxidize β2AR cysteine thiols to Cys-S-OH. In highly oxidative conditions, Cys-S-OH may convert to Cys-SO2H or Cys-SO3H, which are redox-deficient. The role of β2AR redox states in receptor function remains unclear. No prior work has resolved how native, oxidized, or redox-deficient β2AR states affect signaling. This gap motivated further investigation into the β2AR-ROS interplay.

The study aimed to explore how β2AR redox states influence receptor function. It focused on the β2AR-ROS relationship and how receptor oxidation affects downstream signaling. The researchers examined β2AR in native, oxidized, and redox-deficient states. They tested if redox state impacts ligand binding and signaling pathways. The study also sought to determine if redox-deficient β2AR can still signal via Gαs or β-arrestin. The goal was to establish the β2AR-ROS redox axis and its role in receptor activity. This work addresses a specific problem in receptor biology and asthma treatment. The motivation stems from the need to understand β2AR signaling under oxidative stress.

The researchers used clonal cells and a human airway epithelial cell line. These cells endogenously expressed β2AR. They examined β2AR in native, oxidized, and redox-deficient states. Methods included measuring agonist-induced cAMP formation. They also assessed CREB and ERK1/2 phosphorylation via G-protein pathways. β-arrestin-2 recruitment and arrestin-dependent ERK1/2 phosphorylation were analyzed. Internalization of β2AR was also evaluated. The study combined biochemical assays with functional analysis of receptor states.

β2AR was oxidized to Cys-S-OH in situ. Receptor redox state significantly affected ligand binding and function. Homeostatic redox states supported agonist-induced cAMP formation. CREB and G-protein-dependent ERK1/2 phosphorylation were observed in these states. β-arrestin-2 recruitment and arrestin-dependent ERK1/2 phosphorylation also occurred. Redox-deficient β2AR showed reduced signaling via Gαs or β-arrestin. These receptors failed to internalize effectively. The findings highlight a β2AR-ROS redox axis that influences receptor activity.

The study demonstrates that β2AR redox state regulates receptor function. Native and oxidized β2AR support agonist-induced signaling pathways. Redox-deficient β2AR exhibit impaired Gαs and β-arrestin signaling. These findings suggest that ROS and receptor redox states are interdependent. Disturbances in this redox axis may disrupt proper β2AR function. The authors propose that β2AR-ROS interactions are vital for receptor activity. No prior work had resolved this specific mechanism. The results trace directly to the authors’ stated claims.