Vlgr1 is required for proper stereocilia maturation of cochlear hair cells

Authors

  • Hideshi Yagi,

    1. Division of Cell Biology and Neuroscience, Department of Morphological and Physiological Sciences,
    2. Research and Education Program for Life Science, University of Fukui, Fukui 910-1193, Japan
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  • Hisashi Tokano,

    1. Department of Otolaryngology, Tokyo Medical and Dental University, Tokyo 113-8519, Japan
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  • Mitsuyo Maeda,

    1. Department of Anatomy and Neurobiology, Graduate School of Medicine, Osaka City University, Osaka 545-8585, Japan
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  • Tetsuji Takabayashi,

    1. Division of Cell Biology and Neuroscience, Department of Morphological and Physiological Sciences,
    2. Division of Otorhinolaryngology, Department of Sensory and Locomotor Medicine, Faculty of Medical Sciences, University of Fukui, Fukui 910-1193, Japan
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  • Takashi Nagano,

    1. Division of Cell Biology and Neuroscience, Department of Morphological and Physiological Sciences,
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  • Hiroshi Kiyama,

    1. Department of Anatomy and Neurobiology, Graduate School of Medicine, Osaka City University, Osaka 545-8585, Japan
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  • Shigeharu Fujieda,

    1. Division of Otorhinolaryngology, Department of Sensory and Locomotor Medicine, Faculty of Medical Sciences, University of Fukui, Fukui 910-1193, Japan
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  • Ken Kitamura,

    1. Department of Otolaryngology, Tokyo Medical and Dental University, Tokyo 113-8519, Japan
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  • Makoto Sato

    Corresponding author
    1. Division of Cell Biology and Neuroscience, Department of Morphological and Physiological Sciences,
    2. Research and Education Program for Life Science, University of Fukui, Fukui 910-1193, Japan
    3. Solution Oriented Research for Science and Technology (SORST), Japan Science and Technology Agency (JST), Kawaguchi, Saitama 332-0012, Japan
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  • Communicated by: Yoshimi Takai

* Correspondence: E-mail: makosato@fmsrsa.fukui-med.ac.jp

Abstract

Very large G-protein coupled receptor (Vlgr1b) is the largest known G-protein coupled receptor. Its function is unknown, although mice with deletion of Vlgr1 (Vlgr1b together with other splicing variants, Vlgr1c, Vlgr1d and Vlgr1e) are known to exhibit audiogenic seizure susceptibility and VLGR1 is reported to be the gene responsible for Usher type 2C syndrome. We demonstrated here that Vlgr1-mutated mice suffered from a hearing defect because of inner ear dysfunction, as indicated by auditory brainstem response (ABR) and distortion product oto-acoustic emissions (DPOAE). The expression of Vlgr1 was identified in the developing hair cells perinatally, and the translated products were seen to be localized in the base of stereocilia on hair cells using confocal microscopy. This Vlgr1 localization was limited to the base of stereocilia within approximately 200–400 nm from the apical surface of hair cells, as shown by immunoelectron microscopy. The Vlgr1-mutated mice exhibited malformation of the stereocilia; the cochlear hair bundles were apparently normal at birth but then became disarranged at postnatal day 8. Furthermore, the stereocilia in the mutant mice became slanted and disarranged thereafter. These results indicate that loss of Vlgr1 resulted in abnormal development of stereocilia formation.

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