Faculty of Medicine School of Medicine Department of Medical Sciences, Integrative Physiology


Assistant Professor

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Degree 【 display / non-display

  • 博士(医学) ( 2003.3   東京大学 )

Research Areas 【 display / non-display

  • Life Science / Cell biology


Papers 【 display / non-display

  • Temporal and quantitative analysis of the functional expression of Ca(2+)-permeable AMPA receptors during LTP.

    Wakazono Y, Midorikawa R, Takamiya K

    Neuroscience research   2023.7

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    Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1016/j.neures.2023.07.002


  • Distinct cell surface expression patterns of n-glycosylation site mutants of ampa-type glutamate receptor under the homo-oligomeric expression conditions

    Morise J., Yamamoto S., Midorikawa R., Takamiya K., Nonaka M., Takematsu H., Oka S.

    International Journal of Molecular Sciences   21 ( 14 )   1 - 11   2020.7

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    Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:International Journal of Molecular Sciences  

    © 2020 by the authors. Licensee MDPI, Basel, Switzerland. The AMPA-type glutamate receptor (AMPAR) is a homotetrameric or heterotetrameric ion channel composed of various combinations of four subunits (GluA1–4), and its abundance in the synapse determines the strength of synaptic activity. The formation of oligomers in the endoplasmatic reticulum (ER) is crucial for AMPAR subunits’ ER-exit and translocation to the cell membrane. Although N-glycosylation on different AMPAR subunits has been shown to regulate the ER-exit of hetero-oligomers, its role in the ER-exit of homo-oligomers remains unclear. In this study, we investigated the role of N-glycans at GluA1N63/N363 and GluA2N370 in ER-exit under the homo-oligomeric expression conditions, whose mutants are known to show low cell surface expressions. In contrast to the N-glycosylation site mutant GluA1N63Q, the cell surface expression levels of GluA1N363Q and GluA2N370Q increased in a time-dependent manner. Unlike wild-type (WT) GluA1, GluA2WT rescued surface GluA2N370Q expression. Additionally, the expression of GluA1N63Q reduced the cell surface expression level of GluA1WT. In conclusion, our findings suggest that these N-glycans have distinct roles in the ER-exit of GluA1 and GluA2 homo-oligomers; N-glycan at GluA1N63 is a prerequisite for GluA1 ER-exit, whereas N-glycans at GluA1N363 and GluA2N370 control the ER-exit rate.

    DOI: 10.3390/ijms21145101



  • Monitoring the glycosylation of α-amino-3-hydroxy-5-methyl-4-isoxazole-propionate-type glutamate receptors using specific antibodies reveals a novel regulatory mechanism of N-glycosylation occupancy by molecular chaperones in mice.

    Midorikawa R, Takakura D, Morise J, Wakazono Y, Kawasaki N, Oka S, Takamiya K

    Journal of neurochemistry   2020.1

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    Language:Japanese   Publishing type:Research paper (scientific journal)  

    DOI: 10.1111/jnc.14964


  • N-glycosylation of the AMPA-type glutamate receptor regulates cell surface expression and tetramer formation affecting channel function. Reviewed International journal

    Kandel M., Yamamoto S., Midorikawa R., Morise J., Wakazono Y., Oka S., Takamiya K.

    Journal of Neurochemistry   147 ( 6 )   730 - 747   2018.12

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    Authorship:Lead author, Corresponding author   Language:English   Publishing type:Research paper (scientific journal)   Publisher:Journal of Neurochemistry  

    The AMPA-type glutamate receptor (AMPA-R) plays a primary role in principal excitatory synaptic transmission and many neuronal functions including synaptic plasticity that underlie learning and memory. N-glycosylation is one of the major post-translational modifications of membrane proteins, but its specific roles in neurons remain largely unknown. AMPA-R subunits are N-glycosylated at their extracellular domains during their biosynthesis in the lumen of the endoplasmic reticulum and Golgi system. Six N-glycosylation sites are presumed to exist in the extracellular domain of GluA1, which is a member of the AMPA-R subunits. We observed that the intracellular trafficking and cell surface expression were strongly suppressed in the GluA1 mutants lacking N-glycans at N63/N363 in HEK293T cells. Multimer analysis using Blue Native-PAGE displayed the impaired tetramer formation in the glycosylation mutants (N63S and N363S), indicating that the mis-transport was caused by impaired tetramer formation. N63S and N363S mutants were primarily degraded via the lysosomal pathway. Flag-tagged N363S GluA1, but not N63S GluA1, expressed in primary cortical neuron cultures prepared from GluA1 knockout mice was observed to localize at the cell surface. Co-expression of GluA2 partially rescued tetramer formation and the cell surface expression of N363S GluA1 but not N63S GluA1, in HEK293T cells. Electrophysiological analysis also demonstrated functional heteromers of N363S GluA1 with GluA2. These data suggest that site-specific N-glycans on GluA1 subunit regulates tetramer formation, intracellular trafficking, and cell surface expression of AMPA-R. Open science badges: This article has received a badge for *Open Materials* because it provided all relevant information to reproduce the study in the manuscript. The complete Open Science Disclosure form for this article can be found at the end of the article. More information about the Open Practices badges can be found at https://cos.io/our-services/open-science-badges/. (Figure presented.).

    DOI: 10.1111/jnc.14565



  • Autophagy-dependent rhodopsin degradation prevents retinal degeneration in Drosophila. Reviewed

    Midorikawa R, Yamamoto-Hino M, Awano W, Hinohara Y, Suzuki E, Ueda R, Goto S.

    Journal of Neuroscience   2010.8

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    Language:English   Publishing type:Research paper (scientific journal)  

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Presentations 【 display / non-display

  • N型糖鎖修飾を介したAMPA受容体のチャンネル機能制御


    西日本生理学会  (ニュウェルシティー宮崎)  高宮考悟

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    Event date: 2019.11.1 - 2019.11.2

    Language:Japanese   Presentation type:Oral presentation (general)  


    AMPA型グルタミン酸受容体(AMPA受容体)の構成サブユニットの一つであるGluA1は、中枢神経系において神経細胞の興奮性シナプス伝達およびシナプス可塑性の制御に深く関与する。GluA1の細胞外ドメインには計6個のN型糖鎖修飾領域(63N, 249N, 257N, 363N, 401N, 406N) が潜在的に存在するが、その修飾パターンや役割についてはほとんど解明されていない。発表者らは、GluA1のN型糖鎖修飾に着目し、AMPA受容体の機能との関係について解析を行ってきた。その結果、脳内GluA1において401N糖鎖欠失型が有意に存在し、401N糖鎖欠失型GluA1で構成されるAMPA受容体は、グルタミン酸結合後、より持続的なカチオン浸透を示すことがわかった。また、この401N糖鎖欠失型GluA1のもつチャンネル特性は、ガングリオシドGM1との結合を介した脂質ラフトへの局在により発生することが明らかとなった。さらにchemical LTP誘導後の神経細胞において、401N糖鎖欠失型GluA1は脂質ラフト陽性のシナプス後膜に招集されることを示唆する結果を得ており、401N糖鎖欠失型GluA1がシナプス可塑性を制御している可能性が考えられる。

  • Monitoring the glycosylation of AMPA-type glutamate receptors using specific antibodies reveals a novel regulatory mechanism of N-glycosylation occupancy by molecular chaperones International conference

    Ryosuke Midorikawa, Daisuke Takakura, Joji Morise, Nana Kawasaki, Shogo Oka, Kogo Takamiya

    第92回日本生化学大会  (パシフィコ横浜)  新井洋由

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    Event date: 2019.9.18 - 2019.9.20

    Language:English   Presentation type:Poster presentation  


    In the mammalian nervous system, protein N-glycosylation plays important roles in neuronal physiology. In the present study, we performed a comprehensive N-glycosylation analysis of GluA1, one of major subunit of AMPA-type glutamate receptor, which possesses six potential N-glycosylation sites in the N-terminal domain. By Mass Spectrometry (MS)-based analysis, we identified the N-glycoforms and semiquantitatively determined the site-specific N-glycosylation occupancy of GluA1. In addition, only the N401-glycosylation site demonstrated incomplete N-glycosylation occupancy. Therefore, we generated a peptide antibody that specifically detects the N401-glycan-free form to precisely quantify N401-glycosylation occupancy. Using this antibody, we clarified that N401 occupancy varies between cell types and increases in an age-dependent manner in mouse forebrains. To address the regulatory mechanism of N401-glycosylation, binding proteins of GluA1 around the N401 site were screened. HSP 70 family proteins, including Bip, were identified as candidates. Bip has been known as a molecular chaperone that plays a key role in protein folding in the ER. To examine the involvement of Bip in N401-glycosylation, the effect of Bip overexpression on N401 occupancy was evaluated in HEK293T cells, and the results demonstrated that Bip increases the N401-glycan-free form. The N401-glycan-free form in the GluA1 population could be induced by the selective prolongation of its protein half-life, possibly through the selective profolding effect on the N401-glycan-free form by Bip. Taken together, we propose that the N401-glycosite of GluA1 receives a unique control of modification, and we also propose a novel N-glycosylation occupancy regulatory mechanism by molecular chaperones that might be associated with AMPA receptors function in the brain.

  • Activity-dependent modulation of N-glycans in AMPA receptors involves in hippocampal synaptic plasticity

    Ryosuke Midorikawa, yoshihiko Wakazono, Munal Kandel, Nana Kawasaki, and Kogo Takamiya

    Kenji Kadomatsu

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    Event date: 2017.3.3 - 2017.3.4

    Language:English   Presentation type:Poster presentation  

    Venue:Aichi Prefecture  

  • Two N-glycosylation sites are essential for proper tetramer formation and cell surface expression of AMPA-type glutamate receptor

    Kandel Munal Babu, Ryosuke Midorikawa, Kogo Takamiya

    西日本生理学会  (鹿児島市 レインボー鹿児島)  桑木共之

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    Event date: 2016.10.7 - 2016.10.8

    Language:English   Presentation type:Oral presentation (general)  

    Venue:鹿児島市 レインボー鹿児島  

  • GluA1 N-glycosylation regulates channel properties of AMPA receptors.

    Ryosuke Midorikawa, yoshihiko Wakazono, Munal Kandel, Nana Kawasaki, and Kogo Takamiya

    Annual Meeting of Japan Neuroscience Society  (Kanagawa prefecture)  Atsushi Iriki

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    Event date: 2016.7.20 - 2016.7.22

    Language:English   Presentation type:Poster presentation  

    Venue:Kanagawa prefecture  

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Grant-in-Aid for Scientific Research 【 display / non-display

  • グルタミン酸受容体の糖鎖修飾による脳高次機能と精神疾患への関与

    Grant number:21K07483  2021.04 - 2024.03

    独立行政法人日本学術振興会  科学研究費補助金  基盤研究(C)

    高宮 考悟,

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  • キネシンスーパーファミリーKIF4の細胞内における機能解析

    Grant number: 04J84304  2004.04 - 2005.04

    科学研究費補助金  特別研究員推奨費

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    Authorship:Principal investigator 

    キネシンスーパーファミリー(KIFs)に属するKIF4の神経細胞内における機能について、生化学、細胞生物学、及び組織学的手法を用いて解析を行った。まず、Pull down assayによるKIF4結合蛋白質の同定を試みた。その結果、KIF4は核内酵素であるPoly-(ADP ribose) polymerase-1 (PARP-1)に対する抑制因子であることが分かり、これまでのモーター蛋白質にはない新規の機能をもつモーターであることが明らかとなった。続いて、KIF4の神経細胞内における生理機能についての解析を行った結果、以下のことが明らかとなった。
    脱分極化に伴う、核内カルシウム浸透→CAM kinaseIIによるPARP-1の燐酸化→PARP-1のautomodification→KIF4のPARP-1からの解離、及びKIF4の核外への移行→KIF4からの解離による、PARP-1の持続的活性化
    さらに、発生初期での中枢神経系組織の構築におけるKIF4の機能について探るため、in utero electroporationによる大脳皮質神経細胞へのKIF4 deletion mutantの過剰発現を行った。その結果、PARP-1活性に対し抑制作用を持つheadless KIF4を発現させた神経細胞ではアポトーシスが誘導されたのに対し、PARP-1結合領域を欠失したtailless KIF4を発現させた場合では神経細胞の生存に影響がみられないことが確認された。これらのことから、発生段階におけるマウスの神経組織内において、KIF4/PARP-1複合体は、神経細胞の発生運命を制御している可能性が示唆された