2021/10/20 更新

写真a

アマヤ ヨシヒロ
天谷 吉宏
AMAYA Yoshihiro
所属
教育研究院 医歯学系 歯学系列 准教授
医歯学総合研究科 口腔生命科学専攻 准教授
歯学部 歯学科 准教授
職名
准教授
外部リンク

学位

  • 医学博士 ( 1987年3月   熊本大学 )

経歴

  • 新潟大学   歯学部 歯学科   准教授

    2004年4月 - 現在

  • 新潟大学   医歯学総合研究科 口腔生命科学専攻   准教授

    2004年4月 - 現在

  • 新潟大学   歯学部   助手

    1997年7月 - 1999年3月

 

論文

  • Localization and ER membrane insertion of parathyroid hormone-related protein analyzed without effects of reporter proteins. 査読

    Amaya Y, Nakai T

    FEBS letters   2019年8月

  • Evolutionary well-conserved region in the signal peptide of parathyroid hormone-related protein is critical for its dual localization through the regulation of ER translocation 査読

    Yoshihiro Amaya, Toshiki Nakai, Satoshi Miura

    JOURNAL OF BIOCHEMISTRY   159 ( 4 )   393 - 406   2016年4月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:OXFORD UNIV PRESS  

    Parathyroid hormone-related protein (PTHrP) has two different targeting signals: an N-terminal signal peptide for the endoplasmic reticulum (ER) targeting and an internal nuclear localization signal. The protein not only functions as a secretory protein, but is also found in the nucleus and/or nucleolus under certain conditions. PTHrP signal peptide is less hydrophobic than most signal peptides mainly due to its evolutionarily well-conserved region (QQWS). The substitution of four tandem leucine residues for this conserved region resulted in a significant inhibition of the signal peptide cleavage. At the same time, proportion of nuclear and/or nucleolar localization decreased, probably due to tethering of the protein to the ER membrane by the uncleaved mutant signal peptide. Almost complete cleavage of the signal peptide accompanied by a lack of nuclear/nucleolar localization was achieved by combining the hydrophobic h-region and an optimized sequence of the cleavage site. In addition, mutational modifications of the distribution of charged residues in and around the signal peptide affect its cleavage and/or nuclear/nucleolar localization of the protein. These results indicate that the well-conserved region in the signal peptide plays an essential role in the dual localization of PTHrP through ER targeting and/or the membrane translocation.

    DOI: 10.1093/jb/mvv111

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  • Mutations Associated with Functional Disorder of Xanthine Oxidoreductase and Hereditary Xanthinuria in Humans 査読

    Kimiyoshi Ichida, Yoshihiro Amaya, Ken Okamoto, Takeshi Nishino

    INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES   13 ( 11 )   15475 - 15495   2012年11月

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    記述言語:英語   出版者・発行元:MDPI AG  

    Xanthine oxidoreductase (XOR) catalyzes the conversion of hypoxanthine to xanthine and xanthine to uric acid with concomitant reduction of either NAD(+) or O-2. The enzyme is a target of drugs to treat hyperuricemia, gout and reactive oxygen-related diseases. Human diseases associated with genetically determined dysfunction of XOR are termed xanthinuria, because of the excretion of xanthine in urine. Xanthinuria is classified into two subtypes, type I and type II. Type I xanthinuria involves XOR deficiency due to genetic defect of XOR, whereas type II xanthinuria involves dual deficiency of XOR and aldehyde oxidase (AO, a molybdoflavo enzyme similar to XOR) due to genetic defect in the molybdenum cofactor sulfurase. Molybdenum cofactor deficiency is associated with triple deficiency of XOR, AO and sulfite oxidase, due to defective synthesis of molybdopterin, which is a precursor of molybdenum cofactor for all three enzymes. The present review focuses on mutation or chemical modification studies of mammalian XOR, as well as on XOR mutations identified in humans, aimed at understanding the reaction mechanism of XOR and the relevance of mutated XORs as models to estimate the possible side effects of clinical application of XOR inhibitors.

    DOI: 10.3390/ijms131115475

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  • Cleavage of the ER-targeting signal sequence of parathyroid hormone-related protein is cell-type-specific and regulated in Cis by its nuclear localization signal 査読

    Yoshihiro Amaya, Toshiki Nakai, Keiichi Komaru, Masayuki Tsuneki, Satoshi Miura

    JOURNAL OF BIOCHEMISTRY   143 ( 4 )   569 - 579   2008年4月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:OXFORD UNIV PRESS  

    Prepro-parathyroid hormone-related protein (ppPTHrP) has two targeting signals, an N-terminal signal sequence and a nuclear localization signal (NLS). In fact, the protein is not only secreted from the cell but also found in the nucleus and/or nucleolus. In order to understand the function of the PTHrP signal sequence for the dual localization, the signal sequence cleavage of a series of ppPTHrP deletion mutants fused to Escherichia coli leader peptidase was analysed in vitro and in several cell lines. Efficiency of the PTHrP signal sequence cleavage was intrinsically low in the in vitro reconstitution system. In cultured cells, cleavage efficiency of the PTHrP signal sequence varied significantly, being lowest in COS-1 cells, but rising in HeLa, HEK293 and CV-1 cells. However, virtually complete signal sequence cleavage was observed in CHO cells. In addition, the NLS of PTHrP had a negative effect on its own signal sequence cleavage, which could be enhanced by deletion of the spacer sequence between the signal sequence and the NLS. There was a roughly inverse relationship between the signal sequence cleavage and the nuclear localization of PTHrP. Thus, the final destination of PTHrP could be regulated at the ER membrane.

    DOI: 10.1093/jb/mvn002

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  • Novel aggregate formation of a frame-shift mutant protein of tissue-nonspecific alkaline phosphatase is ascribed to three cysteine residues in the C-terminal extension - Retarded secretion and proteasomal degradation 査読

    K Komaru, Y Ishida, Y Amaya, M Goseki-Sone, H Orimo, K Oda

    FEBS JOURNAL   272 ( 7 )   1704 - 1717   2005年4月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:BLACKWELL PUBLISHING LTD  

    In the majority of hypophosphatasia patients, reductions in the serum levels of alkaline phosphatase activity are caused by various missense mutations in the tissue-nonspecific alkaline phosphatase (TNSALP) gene. A unique frame-shift mutation due to a deletion of T at cDNA number 1559 [TNSALP (1559delT)] has been reported only in Japanese patients with high allele frequency. In this study, we examined the molecular phenotype of TNSALP (1559delT) using in vitro translation/translocation system and COS-1 cells transiently expressing this mutant protein. We showed that the mutant protein not only has a larger molecular size than the wild type enzyme by approximate to 12 kDa, reflecting an 80 amino acid-long extension at its C-terminus, but that it also lacks a glycosylphosphatidylinositol anchor. In support of this, alkaline phosphatase activity of the cells expressing TNSALP (1559delT) was localized at the juxtanucleus position, but not on the cell surface. However, only a limited amount of the newly synthesized protein was released into the medium and the rest was polyubiquitinated, followed by degradation in the proteasome. SDS/PAGE and analysis by sucrose-density-gradient analysis indicated that TNSALP (1559delT) forms a disulfide-bonded high-molecular-mass aggregate. Interestingly, the aggregate form of TNSALP (1559delT) exhibited a significant enzyme activity. When all three cysteines at positions of 506, 521 and 577 of TNSALP (1559delT) were replaced with serines, the aggregation disappeared and instead this modified mutant protein formed a noncovalently associated dimer, strongly indicating that these cysteine residues in the C-terminal region are solely responsible for aggregate formation by cross-linking the catalytically active dimers. Thus, complete absence of TNSALP on cell surfaces provides a plausible explanation for a severe lethal phenotype of a homozygote hypophosphatasia patient carrying TNSALP (1559delT).

    DOI: 10.1111/j.1742-4658.2005.04597.x

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  • Tissue-nonspecific alkaline phosphatase with an Asp(289)-> Val mutation fails to reach the cell surface and undergoes proteasome-mediated degradation 査読

    Y Ishida, K Komaru, M Ito, Y Amaya, S Kohno, K Oda

    JOURNAL OF BIOCHEMISTRY   134 ( 1 )   63 - 70   2003年7月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:JAPANESE BIOCHEMICAL SOC  

    A missense mutation in the gene of tissue-nonspecific alkaline phosphatase, which replaces aspartic acid at position 289 with valine [TNSALP (D289V)], was reported in a lethal hypophosphatasia patient [Taillandier, A. et al. (1999) Hum. Mut. 13, 171-172]. To define the molecular defects of TNSALP (D289V), this mutant protein in transiently transfected COS-1 cells was analyzed biochemically and morphologically. TNSALP (D289V) exhibited no alkaline phosphatase activity and mainly formed a disulfide-linked high molecular mass aggregate. Cell-surface biotinylation, digestion with phosphatidylinositol-specific phospholipase C and an immunofluorescence study showed that the mutant protein failed to appear on the cell surface and was accumulated intracellularly. In agreement with this, pulse/chase experiments demonstrated that TNSALP (D289V) remained endo-beta-N-acetyl-glucosaminidase H-sensitive throughout the chase and was eventually degraded, indicating that the mutant protein is unable to reach the medial-Golgi. Proteasome inhibitors strongly blocked the degradation of TNSALP (D289V), and furthermore the mutant protein was found to be ubiquitinated. Besides, another naturally occurring TNSALP with a Glu(218)-->Gly mutation was also found to be polyubiquitinated and degraded in the proteasome. Since the acidic amino acids at positions 218 and 289 of TNSALP are thought to be directly involved in the Ca2+ coordination, these results suggest the critical importance of calcium binding in post-translational folding and assembly of the TNSALP molecule.

    DOI: 10.1093/jb/mvg114

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  • Purification and characterization of multiple forms of rat liver xanthine oxidoreductase expressed in baculovirus-insect cell system 査読

    T Nishino, Y Amaya, S Kawamoto, Y Kashima, K Okamoto, T Nishino

    JOURNAL OF BIOCHEMISTRY   132 ( 4 )   597 - 606   2002年10月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:OXFORD UNIV PRESS  

    cDNA of rat liver xanthine oxidoreductase (XOR), a molybdenum-containing iron-sulfur flavoprotein, was expressed in a baculovirus-insect cell system. The expressed XOR consisted of a heterogeneous mixture of native dimeric, demolybdo-dimeric, and monomeric forms, each of which was separated and purified to homogeneity. All the expressed forms contained flavin, of which the semiquinone form was stable during dithionite titration after dithiothreitol treatment, indicating that the flavin domains of all the expressed molecules have the intact conformations interconvertible between NAD(+)-dependent dehydrogenase (XDH) and O-2-dependent oxidase (XO) types. The absorption spectrum and metal analyses showed that the monomeric form lacks not only molybdopterin but also one of the iron-sulfur centers. The reductive titration of the monomer with dithionite showed that the monomeric form required only three electrons for complete reduction, and the redox potential of the iron-sulfur center in the monomeric form is a lower value than that of FAD. In contrast to native or demolybdo-dimeric XDHs, the monomer showed a very slow reductive process with NADH under anaerobic conditions, although the conformation around FAD is a dehydrogenase form, suggesting the important role of the iron-sulfur center in the reductive process of FAD with the reduced pyridine nucleotide.

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MISC

  • ''Save the Town": Insolvable Dilemmas of Fukushima's "Return Policy" 査読

    Hirano Katsuya, Amaya Yoshihiro, Kawano Yoh, Tamotsu Namie, Mayor Baba

    ASIA-PACIFIC JOURNAL-JAPAN FOCUS   16 ( 3 )   2018年1月

  • Reconstruction Disaster: The human implications of Japan's forced return policy in Fukushima 査読

    Yuichi Suzuki, Hirano Katsuya, Amaya Yoshihiro, Kawano Yoh

    ASIA-PACIFIC JOURNAL-JAPAN FOCUS   15 ( 7 )   2017年4月

 

担当経験のある授業科目

  • 人体のしくみ

    2020年
    -
    現在
    機関名:新潟大学

  • 分子細胞生物学演習ⅠA

    2018年
    機関名:新潟大学

  • 基礎生化学

    2018年
    機関名:新潟大学

  • 生化学Ⅱ

    2016年
    -
    2017年
    機関名:新潟大学

  • 早期臨床実習Ⅱ

    2016年
    機関名:新潟大学

  • 口腔生化学

    2016年
    機関名:新潟大学

  • 歯学研究入門

    2014年
    -
    2015年
    機関名:新潟大学

  • 生化学実習

    2010年
    -
    現在
    機関名:新潟大学

  • 栄養学

    2010年
    -
    現在
    機関名:新潟大学

  • 生化学Ⅰ

    2010年
    -
    2017年
    機関名:新潟大学

  • ゲノム検査科学

    2010年
    -
    2014年
    機関名:新潟大学

  • 硬組織生化学演習

    2009年
    機関名:新潟大学

  • 遺伝子工学概論

    2009年
    機関名:新潟大学

  • 細胞生物学実習

    2008年
    -
    2009年
    機関名:新潟大学

  • 基礎科学演習

    2007年
    -
    2016年
    機関名:新潟大学

  • 細胞生物学1

    2007年
    -
    2009年
    機関名:新潟大学

  • 栄養指導・栄養学

    2007年
    -
    2009年
    機関名:新潟大学

  • 生物化学

    2007年
    -
    2008年
    機関名:新潟大学

  • 細胞生物学実習I

    2007年
    機関名:新潟大学

  • 細胞生物学2

    2007年
    機関名:新潟大学

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