title: Ligand-directed functional selectivity at the mu opioid receptor revealed by label-free integrative pharmacology on-target.
abstract: Development of new opioid drugs that provide analgesia without producing dependence is important for pain treatment. Opioid agonist drugs exert their analgesia effects primarily by acting at the mu opioid receptor (MOR) sites. High-resolution differentiation of opioid ligands is crucial for the development of new lead drug candidates with better tolerance profiles. Here, we use a label-free integrative pharmacology on-target (iPOT) approach to characterize the functional selectivity of a library of known opioid ligands for the MOR. This approach is based on the ability to detect dynamic mass redistribution (DMR) arising from the activation of the MOR in living cells. DMR assays were performed in HEK-MOR cells with and without preconditioning with probe molecules using label-free resonant waveguide grating biosensors, wherein the probe molecules were used to modify the activity of specific signaling proteins downstream the MOR. DMR signals obtained were then translated into high resolution heat maps using similarity analysis based on a numerical matrix of DMR parameters. Our data indicate that the iPOT approach clearly differentiates functional selectivity for distinct MOR signaling pathways among different opioid ligands, thus opening new avenues to discover and quantify the functional selectivity of currently used and novel opioid receptor drugs.
authors: Department of Pharmacology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania, United States of America.
authors: Megan
authors: M
authors: Morse
authors: Elizabeth
authors: E
authors: Tran
authors: Haiyan
authors: H
authors: Sun
authors: Robert
authors: R
authors: Levenson
authors: Ye
authors: Y
authors: Fang
mesh_terms: D000242:Cyclic AMP / Q000096:biosynthesis; D055808:Drug Discovery / Q000379:methods*; D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D008024:Ligands; D011494:Protein Kinases / Q000378:metabolism; D017450:Receptors, Opioid, mu / Q000819:agonists / Q000037:antagonists & inhibitors / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D054852:Small Molecule Libraries / Q000378:metabolism / Q000494:pharmacology; D013379:Substrate Specificity
chemical_list: D008024:Ligands; D017450:Receptors, Opioid, mu; D054852:Small Molecule Libraries; D000242:Cyclic AMP; D011494:Protein Kinases; D019206:GTP-Binding Protein alpha Subunits, Gi-Go