title: Ligand-selective activation of heterologously-expressed mammalian olfactory receptor.
abstract: Mammalian olfactory receptors (ORs) appear to have the capacity to couple to multiple G protein-coupled signaling pathways in a ligand-dependent selective manner. To better understand the mechanisms and molecular range of such ligand selectivity, we expressed the mouse eugenol OR (mOR-EG) in HEK293T cells together with Gα15 to monitor activation of the phospholipase-C (PLC) signaling pathway and/or Gαolf to monitor activation of the adenylate cyclase (AC) signaling pathway, resulting in intracellular Ca(2+) release and/or Ca(2+) influx through a cyclic nucleotide-gated channel, respectively. PLC-dependent responses differed dynamically from AC-dependent responses, allowing them to be distinguished when Gα15 and Gαolf were co-expressed. The dynamic difference in readout was independent of the receptor, the heterologous expression system, and the ligand concentration. Of 17 reported mOR-EG ligands tested, including eugenol, its analogs, and structurally dissimilar compounds (mousse cristal, nootkatone, orivone), some equally activated both signaling pathways, some differentially activated both signaling pathways, and some had no noticeable effect even at 1-5mM. Our findings argue that mOR-EG, when heterologously expressed, can couple to two different signaling pathways in a ligand selective manner. The challenge now is to determine the potential of mOR-EG, and perhaps other ORs, to activate multiple signaling pathways in a ligand selective manner in native ORNs.
authors.affiliation: Whitney Laboratory, Center for Smell and Taste, and McKnight Brain Institute, University of Florida, Gainesville, FL 32610, United States. Electronic address: ukhanov@mbi.ufl.edu.
authors.forename: K
authors.initials: K
authors.lastname: Ukhanov
authors.affiliation: Whitney Laboratory, Center for Smell and Taste, and McKnight Brain Institute, University of Florida, Gainesville, FL 32610, United States.
authors.forename: Y
authors.initials: Y
authors.lastname: Bobkov
authors.affiliation: Whitney Laboratory, Center for Smell and Taste, and McKnight Brain Institute, University of Florida, Gainesville, FL 32610, United States.
authors.forename: E A
authors.initials: EA
authors.lastname: Corey
authors.affiliation: Whitney Laboratory, Center for Smell and Taste, and McKnight Brain Institute, University of Florida, Gainesville, FL 32610, United States; Department of Biology, University of Florida, Gainesville, FL 32610, United States; Department of Neuroscience, University of Florida, Gainesville, FL 32610, United States.
authors.forename: B W
authors.initials: BW
authors.lastname: Ache
mesh_terms: D000262:Adenylyl Cyclases / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D000242:Cyclic AMP / Q000378:metabolism; D015870:Gene Expression / Q000187:drug effects; D006579:Heterozygote; D006801:Humans; D008024:Ligands; D008322:Mammals / Q000378:metabolism; D051379:Mice; D018034:Olfactory Receptor Neurons / Q000187:drug effects* / Q000378:metabolism; D018035:Receptors, Odorant / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology; D010738:Type C Phospholipases / Q000378:metabolism; D008840:Microfilament Proteins
chemical_list: D000262:Adenylyl Cyclases; D002118:Calcium; D000242:Cyclic AMP; D008024:Ligands; D018035:Receptors, Odorant; D010738:Type C Phospholipases; C544141:Olfr73 protein, mouse; D008840:Microfilament Proteins
keywords: Biased signaling; Functional assay; HEK293T; Olfactory receptor; mOR-EG; olfr73