(1376-A) Structure-guided monitoring of the human opioid receptor family using BRET assays
Monday, February 5, 2024
12:00 PM – 1:00 PM EST
Location: Exhibit Halls AB
Abstract: The human opioid system comprises four opioid receptors: µOR, δOR, κOR and NOPR (nociceptin opioid peptide receptor). Each of these G protein-coupled receptors has a set of related endogenous opioid peptides with distinct selectivity for their respective receptor. Structures of the entire human opioid receptor family with bound opioid peptides have been determined by cryo-electron microscopy and are now publicly available. Structure-guided biochemical studies have also been performed for each of these receptors and their mutants to better understand the mechanisms of how endogenous or exogenous peptides interact with the different types of receptors.
Currently opioid drugs are the strongest pain relievers available, but they are often accompanied by severe side effects. Researchers therefore want to better understand the mechanisms of peptide-receptor selectivity and drug signaling. By combining structural information with details on the mechanism of action, a framework is provided that facilitates the rational design of safer opioid drugs for pain relief.
Here, to contribute to this framework, we used two types of biochemical assays: (1) G protein dissociation studies and (2) β-arrestin recruitment. β-arrestins turn off further signaling by the active receptor and can act as scaffolds for effectors mediating G protein-independent signaling. Gi dissociation concentration-response curves were obtained for peptide ligands at µOR, δOR, κOR and NOPR. In addition, both Gi dissociation and β-arrestin recruitment curves were obtained for mutants of each receptor. The BRET measurements revealed distinct differences in the β-arrestin recruitment and Gi protein dissociation for the different mutants. These findings serve as a useful starting point for future experiments looking at the mechanism of G protein signaling and may serve as a powerful starting point for the design of more potent G protein-biased agonists with fewer side effects.