PQBP-1 is expressed predominantly in the central nervous system during development

Authors

  • Yunglong Qi,

    1. Department of Neuropathology, Medical Research Institute, Tokyo Medical and Dental University, 21st Century COE, Brain Integration and Its Disorders, 1-5-45, Yushima, Bunkyo-ku, Tokyo 113–8510, Japan
    2. Department of Orthopedics, Tokyo Medical and Dental University, 21st Century COE, Molecular Destruction and Reconstruction of Tooth and Bone, Tokyo, Japan
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  • Masataka Hoshino,

    1. Department of Neuropathology, Medical Research Institute, Tokyo Medical and Dental University, 21st Century COE, Brain Integration and Its Disorders, 1-5-45, Yushima, Bunkyo-ku, Tokyo 113–8510, Japan
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  • Yo-ichi Wada,

    1. Department of Neuropathology, Medical Research Institute, Tokyo Medical and Dental University, 21st Century COE, Brain Integration and Its Disorders, 1-5-45, Yushima, Bunkyo-ku, Tokyo 113–8510, Japan
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  • Shigeki Marubuchi,

    1. Department of Neuropathology, Medical Research Institute, Tokyo Medical and Dental University, 21st Century COE, Brain Integration and Its Disorders, 1-5-45, Yushima, Bunkyo-ku, Tokyo 113–8510, Japan
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  • Natsue Yoshimura,

    1. Department of Neuropathology, Medical Research Institute, Tokyo Medical and Dental University, 21st Century COE, Brain Integration and Its Disorders, 1-5-45, Yushima, Bunkyo-ku, Tokyo 113–8510, Japan
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  • Ichiro Kanazawa,

    1. National Center for Neurology and Psychiatry, Kodaira, Japan
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  • Ken-ichi Shinomiya,

    1. Department of Orthopedics, Tokyo Medical and Dental University, 21st Century COE, Molecular Destruction and Reconstruction of Tooth and Bone, Tokyo, Japan
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  • Hitoshi Okazawa

    1. Department of Neuropathology, Medical Research Institute, Tokyo Medical and Dental University, 21st Century COE, Brain Integration and Its Disorders, 1-5-45, Yushima, Bunkyo-ku, Tokyo 113–8510, Japan
    2. Japan Science and Technology Agency (JST), PRESTO, Kawagoe, Japan
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Dr H. Okazawa, 1Department of Neuropathology, as above.
E-mail: okazawa-tky@umin.ac.jp

Summary

Mutations of PQBP-1 (polyglutamine binding protein-1) have been shown recently to cause human mental retardation accompanied by microcephaly at a high frequency. As a first step towards understanding the molecular basis of this developmental anomaly, we analysed developmental expression of PQBP-1 by in situ hybridization, immunohistochemsitry and Western blot analysis. Although it had been shown by Northern blot analysis that PQBP-1 mRNA is expressed in multiple organs in adult mice, our present results revealed that PQBP-1 mRNA and protein are dominantly expressed in the central nervous system (CNS) in embryos and in newborn mice. The mean expression level of PQBP-1 reaches a peak around birth and is down-regulated in adulthood. Furthermore, the expression pattern in the CNS changes remarkably following birth. PQBP-1 mRNA in the cerebral cortex is high in embryos but it rapidly decreases after birth. PQBP-1 mRNA increases in external and internal granular cell layers of the cerebellum from postnatal day 1 (P1) to P5. In addition, expression in the subventricular zone, where neurogenesis occurs, was high from P5 to adulthood. Collectively, these findings suggest that PQBP-1 might be involved in neuronal proliferation and/or maturation. These ideas may be relevant to the insufficient growth of brain structure reported in PQBP-1-linked human mental retardation.

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