title: Two highly homologous mouse odorant receptors encoded by tandemly-linked MOR29A and MOR29B genes respond differently to phenyl ethers.
abstract: Since the discovery of odorant receptors (ORs) in rodents, most ORs have remained orphan receptors. Even for deorphanized ORs in vitro, their in vivo properties are largely unknown. Here, we report odor response profiles of two highly homologous mouse ORs, MOR29A and MOR29B, both in vivo and in vitro. The BAC transgenic mouse was generated, in which olfactory sensory neurons (OSNs) expressing the transgenes MOR29A and MOR29B were differently tagged with IRES-gapECFP and IRES-gapEYFP, respectively. MOR29A- and MOR29B-expressing OSN axons converged on separate but nearby loci on the dorsal surface of the olfactory bulb (OB). Optical imaging of intrinsic signals in the OB identified five different phenyl ethers as candidate ligands for MOR29B. Based on in vitro calcium imaging with the isolated OSNs and luciferase assay with heterologous cells, only guaiacol and vanillin were found to be potent agonists for MOR29A and MOR29B. Because of its accessible glomerular locations in the dorsal OB and defined odor response profiles both in vivo and in vitro, the MOR29A/29B tagging mouse will serve as an excellent tool for studying both odor-signal processing and neural circuitry in the OB.
authors.affiliation: Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo 113-0032, Japan. atsuboi@naramed-u.ac.jp
authors.forename: Akio
authors.initials: A
authors.lastname: Tsuboi
authors.forename: Takeshi
authors.initials: T
authors.lastname: Imai
authors.forename: Hiroyuki K
authors.initials: HK
authors.lastname: Kato
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Matsumoto
authors.forename: Kei M
authors.initials: KM
authors.lastname: Igarashi
authors.forename: Misao
authors.initials: M
authors.lastname: Suzuki
authors.forename: Kensaku
authors.initials: K
authors.lastname: Mori
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Sakano
mesh_terms: D000818:Animals; D001547:Benzaldehydes / Q000737:chemistry / Q000378:metabolism; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D006139:Guaiacol / Q000737:chemistry / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D015394:Molecular Structure; D009830:Olfactory Bulb / Q000033:anatomy & histology; D009833:Olfactory Pathways / Q000378:metabolism; D018034:Olfactory Receptor Neurons / Q000166:cytology / Q000378:metabolism*; D010647:Phenyl Ethers / Q000737:chemistry / Q000378:metabolism*; D018035:Receptors, Odorant / Q000235:genetics / Q000378:metabolism*; D019076:Transgenes
chemical_list: D001547:Benzaldehydes; D010647:Phenyl Ethers; D018035:Receptors, Odorant; D006139:Guaiacol; C100058:vanillin