title: Evaluating cellular impedance assays for detection of GPCR pleiotropic signaling and functional selectivity.
abstract: G-protein-coupled receptors can couple to different signal transduction pathways in different cell types (termed cell-specific signaling) and can activate different signaling pathways depending on the receptor conformation(s) stabilized by the activating ligand (functional selectivity). These concepts offer potential for developing pathway-specific drugs that increase efficacy and reduce side effects. Despite significant interest, functional selectivity has been difficult to exploit in drug discovery, in part due to the burden of multiple assays. Cellular impedance assays use an emerging technology that can qualitatively distinguish Gs, Gi/o, and Gq signaling in a single assay and is thereby suited for studying these pharmacological concepts. Cellular impedance confirmed cell-specific Gs and Gq coupling for the melanocortin-4 receptor and dual Gi and Gs signaling with the cannabinoid-1 (CB1) receptor. The balance of Gi versus Gs signaling depended on the cell line. In CB1-HEKs, Giand Gs-like responses combined to yield a novel impedance profile demonstrating the dynamic nature of these traces. Cellspecific signaling was observed with endogenous D1 receptor in U-2 cells and SK-N-MC cells, yet the pharmacological profile of partial and full agonists was similar in both cell lines. We conclude that the dynamic impedance profile encodes valuable relative signaling information and is sufficiently robust to help evaluate cell-specific signaling and functional selectivity.
authors.affiliation: Lead Generation Department, AstraZeneca Pharmaceuticals LP, Wilmington, Delaware 19810, USA. matt.peters@astrazeneca.com
authors.forename: Matthew F
authors.initials: MF
authors.lastname: Peters
authors.forename: Clay W
authors.initials: CW
authors.lastname: Scott
mesh_terms: D000818:Animals; D001681:Biological Assay / Q000379:methods*; D001932:Brain Neoplasms / Q000378:metabolism / Q000473:pathology; D016466:CHO Cells; D018929:Cell Culture Techniques; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D006224:Cricetinae; D003412:Cricetulus; D015638:Cytochalasin D / Q000494:pharmacology; D018491:Dopamine Agonists / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D017097:Electric Impedance; D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000187:drug effects / Q000378:metabolism*; D043802:GTP-Binding Protein alpha Subunits, Gq-G11 / Q000187:drug effects / Q000378:metabolism*; D019205:GTP-Binding Protein alpha Subunits, Gs / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D020128:Inhibitory Concentration 50; D007668:Kidney / Q000166:cytology; D018241:Neuroectodermal Tumors, Primitive, Peripheral / Q000378:metabolism / Q000473:pathology; D012516:Osteosarcoma / Q000378:metabolism / Q000473:pathology; D037342:Pertussis Toxin / Q000494:pharmacology; D043643:Receptor, Muscarinic M1 / Q000378:metabolism; D017448:Receptors, Dopamine D2 / Q000378:metabolism; D050641:Receptors, Dopamine D5 / Q000378:metabolism; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism*; D012680:Sensitivity and Specificity; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D000521:alpha-MSH / Q000819:agonists / Q000031:analogs & derivatives
chemical_list: D018491:Dopamine Agonists; D043643:Receptor, Muscarinic M1; D017448:Receptors, Dopamine D2; D043562:Receptors, G-Protein-Coupled; D050641:Receptors, Dopamine D5; D015638:Cytochalasin D; D000521:alpha-MSH; D037342:Pertussis Toxin; D019206:GTP-Binding Protein alpha Subunits, Gi-Go; D043802:GTP-Binding Protein alpha Subunits, Gq-G11; D019205:GTP-Binding Protein alpha Subunits, Gs