Two highly homologous mouse odorant receptors encoded by tandemly-linked MOR29A and MOR29B genes respond differently to phenyl ethers

Authors

  • Akio Tsuboi,

    1. Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo 113-0032, Japan
    2. Laboratory for Molecular Biology of Neural System, Advanced Medical Research Center, Nara Medical University, Kashihara, Nara, Japan
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    • These authors contributed equally to this work.

  • Takeshi Imai,

    1. Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo 113-0032, Japan
    2. Laboratory for Sensory Circuit Formation, RIKEN Center for Developmental Biology, Kobe, Japan
    3. PRESTO, Japan Science and Technology Agency (JST), Saitama, Japan
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    • These authors contributed equally to this work.

  • Hiroyuki K. Kato,

    1. Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo 113-0032, Japan
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  • Hideyuki Matsumoto,

    1. Department of Physiology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
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  • Kei M. Igarashi,

    1. Department of Physiology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
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  • Misao Suzuki,

    1. Center for Animal Resources and Development, Kumamoto University, Kumamoto, Japan
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  • Kensaku Mori,

    1. Department of Physiology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
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  • Hitoshi Sakano

    1. Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo 113-0032, Japan
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Akio Tsuboi, 2Nara Medical University,
E-mail: atsuboi@naramed-u.ac.jp
Hitoshi Sakano, 1The University of Tokyo,
E-mail: sakano@mail.ecc.u-tokyo.ac.jp

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.

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