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Affiliation |
Faculty of Medicine School of Medicine Department of Infectious Diseases, Microbiology |
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Associate Professor |
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External Link |
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IMAMURA Morikazu
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Degree 【 display / non-display 】
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博士（農学） ( 1999.3 東京農工大学 )
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修士（理学） ( 1995.3 首都大学東京 )
Papers 【 display / non-display 】
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Central residues in prion protein PrP<sup>C</sup> are crucial for its conversion into the pathogenic isoform. Reviewed International coauthorship
Pasiana AD, Miyata H, Chida J, Hara H, Imamura M, Atarashi R, and Sakaguchi S.
J Biol Chem 298 ( 9 ) 102381 2022.9
Language：English Publishing type：Research paper (scientific journal) Publisher：Journal of Biological Chemistry
Conformational conversion of the cellular prion protein, PrPC, into the amyloidogenic isoform, PrPSc, is a key pathogenic event in prion diseases. However, the conversion mechanism remains to be elucidated. Here, we generated Tg(PrPΔ91-106)-8545/Prnp0/0 mice, which overexpress mouse PrP lacking residues 91-106. We showed that none of the mice became sick after intracerebral inoculation with RML, 22L, and FK-1 prion strains nor accumulated PrPScΔ91-106 in their brains except for a small amount of PrPScΔ91-106 detected in one 22L-inoculated mouse. However, they developed disease around 85 days after inoculation with bovine spongiform encephalopathy (BSE) prions with PrPScΔ91-106 in their brains. These results suggest that residues 91-106 are important for PrPC conversion into PrPSc in infection with RML, 22L, and FK-1 prions but not BSE prions. We then narrowed down the residues 91-106 by transducing various PrP deletional mutants into RML- and 22L-infected cells and identified that PrP mutants lacking residues 97-99 failed to convert into PrPSc in these cells. Our in vitro conversion assay also showed that RML, 22L, and FK-1 prions did not convert PrPΔ97-99 into PrPScΔ97-99, but BSE prions did. We further found that PrP mutants with proline residues at positions 97 to 99 or charged residues at positions 97 and 99 completely or almost completely lost their converting activity into PrPSc in RML- and 22L-infected cells. These results suggest that the structurally flexible and noncharged residues 97-99 could be important for PrPC conversion into PrPSc following infection with RML, 22L, and FK-1 prions but not BSE prions.
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Takatsuki H, Imamura M, Mori T, Atarashi R
Sci Rep 12 ( 1 ) 7923 2022.5
Language：English Publishing type：Research paper (scientific journal) Publisher：Scientific Reports
Each prion strain has its own characteristics and the efficacy of anti-prion drugs varies. Screening of prion disease therapeutics is typically evaluated by measuring amounts of protease-resistant prion protein (PrP-res). However, it remains unclear whether such measurements correlate with seeding activity, which is evaluated by real-time quaking-induced conversion (RT-QuIC). In this study, the effects of anti-prion compounds pentosan polysulfate (PPS), Congo red, and alprenolol were measured in N2a58 cells infected with Fukuoka-1 (FK1) or 22L strain. The compounds abolished PrP-res and seeding activity, except for N2a58/FK1 treated with PPS. Interestingly, the seeding activity of N2a58/FK1, which was reduced in the presence of PPS, was not lost and remained at low levels. However, upon removal of PPS, both were gradually restored to their original levels. These results indicate that low-level persistent prion infection keeping measurable seeding activity is induced by PPS in a strain-dependent manner. Furthermore, for protein misfolding cyclic amplification (PMCA), the anti-prion effect of PPS decreased in FK1 compared to 22L, suggesting that the differences occur at the level of the direct conversion. Our findings demonstrate that the advantages of RT-QuIC and PMCA can be exploited for more accurate assessment of therapeutic drug screening, reflecting strain differences.
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Imamura M, Tabeta N, Iwamaru Y, Takatsuki H, Mori T, Atarashi R
Biochem Biophys Res Commun 613 67 - 72 2022.5
Authorship：Lead author, Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：Biochemical and Biophysical Research Communications
Prion diseases are transmissible and progressive neurodegenerative disorders characterized by abnormal prion protein (PrPSc) accumulation in the central nervous system. Generation of synthetic PrPSc in a cell-free conversion system and examination of its transmissibility to animals would facilitate testing of the protein-only hypothesis and the understanding of the molecular basis of sporadic prion diseases. In this study, we used recombinant prion protein from a baculovirus-insect cell expression system (Bac-rPrP) and insect cell-derived cofactors to determine whether Bac-rPrPSc is spontaneously produced in intermittent ultrasonic reactions. No spontaneous generation of Bac-rPrPSc was observed at 37 °C, but when the reaction temperature was increased to 45 °C, Bac-rPrPSc was generated in all trials. Some Bac-rPrPSc variants were transmissible to mice, but when the reaction was repeated for 40 rounds, the transmissibility was lost. Notably, a variety of Bac-rPrPSc variants, including non-transmissible ones, differing in resistance to proteinase K and cofactor dependence during amplification, was generated under the same experimental conditions, including the same sonication settings and cofactors. However, their characteristics also disappeared after 40 reaction rounds and the variety converged onto a single variant. These results indicate that various Bac-rPrPSc variants with different transmissibility to mice and structural properties are generated, which compete with each other and gradually converge onto a variant with a slightly faster amplification rate.
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Matsuura Y., Miyazawa K., Horiuchi M., Suzuki A., Yokoyama M., Imamura M., Ikeda K., Iwamaru Y.
Microbiology and Immunology 66 ( 5 ) 212 - 215 2022.5
Language：English Publishing type：Research paper (scientific journal) Publisher：Microbiology and Immunology
Chronic wasting disease (CWD) is a prion disease affecting cervid species primarily in the United States of America and Canada; however, it is now emerging in Scandinavian countries. Although CWD cases have not been reported in Japan, in case of a CWD outbreak occuring, it is critical to prepare for testing a large number of specimens. The present study showed that a rapid post-mortem test kit, which is used for bovine spongiform encephalopathy surveillance in Japan, is valid for the detection of CWD prion.
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Ethanolamine is a new anti‐prion compound
Uchiyama K., Hara H., Chida J., Pasiana A.D., Imamura M., Mori T., Takatsuki H., Atarashi R., Sakaguchi S.
International Journal of Molecular Sciences 22 ( 21 ) 2021.11
Language：Japanese Publishing type：Research paper (scientific journal) Publisher：International Journal of Molecular Sciences
Prion diseases are a group of fatal neurodegenerative disorders caused by accumulation of proteinaceous infectious particles, or prions, which mainly consist of the abnormally folded, am-yloidogenic prion protein, designated PrPSc. PrPSc is produced through conformational conversion of the cellular isoform of prion protein, PrPC, in the brain. To date, no effective therapies for prion diseases have been developed. In this study, we incidentally noticed that mouse neuroblastoma N2a cells persistently infected with 22L scrapie prions, termed N2aC24L1‐3 cells, reduced PrPSc levels when cultured in advanced Dulbecco’s modified eagle medium (DMEM) but not in classic DMEM. PrPC levels remained unchanged in prion‐uninfected parent N2aC24 cells cultured in advanced DMEM. These results suggest that advanced DMEM may contain an anti‐prion compound(s). We then successfully identified ethanolamine in advanced DMEM has an anti‐prion activity. Ethanola-mine reduced PrPSc levels in N2aC24L1‐3 cells, but not PrPC levels in N2aC24 cells. Also, oral administration of ethanolamine through drinking water delayed prion disease in mice intracerebrally inoculated with RML scrapie prions. These results suggest that ethanolamine could be a new anti-prion compound.
MISC 【 display / non-display 】
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バキュロウイルス-昆虫細胞発現組換えPrP を用いた試験管内変換系の構築に基づくプリオン変換・生成機構の解明. Invited
今村守一，森剛志，高月英恵，岩丸祥史，新竜一郎
YAKUGAKU ZASSHI 139 ( 7 ) 989 - 992 2019.7
Language：Japanese Publishing type：Article, review, commentary, editorial, etc. (scientific journal) Publisher：公益財団法人日本薬学会
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十二指腸乳頭部癌-現状の問題点と今後の展望-経十二指腸的乳頭部癌切除の手技と適応. Invited
今村直哉, 七島篤志, 濵田剛臣, 矢野公一, 旭吉雅秀, 藤井義郎, 武野慎祐, 池田拓人, 河野文彰, 久保田良政, 坂哲臣, 河上洋
胆と膵. 2017
Language：Japanese Publishing type：Article, review, commentary, editorial, etc. (scientific journal)
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牛海綿状脳症（BSE）の診断：異常型プリオンタンパク質の検出
今村守一，横山隆
ぶんせき 7 347 - 351 2006.7
Language：Japanese Publishing type：Article, review, commentary, editorial, etc. (scientific journal) Publisher：日本分析化学会
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昆虫抗菌ペプチド遺伝子の導入による細菌病抵抗性植物の作出
今村守一，山川稔
実験医学 18 ( 6 ) 771 - 773 2000.3
Language：Japanese Publishing type：Article, review, commentary, editorial, etc. (scientific journal) Publisher：羊土社
Presentations 【 display / non-display 】
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スクレイピー感染ヒツジ脳には複数のプリオン株が混在している.
今村守一, 宮澤光太郎, 森剛志, 髙月英恵, 新竜一郎
九州微生物研究フォーラム2021 2021.9.11
Event date： 2021.9.10 - 2021.9.11
Language：Japanese Presentation type：Oral presentation (general)
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さまざまなリコンビナントプリオン蛋白を基質としたRT-QUIC法の反応性の比較解析.
森剛志, 今村守一, 高月英恵, 井口洋美, 大野美奈子, 新竜一郎
第67回日本ウイルス学会学術集会 (東京（江戸川区）) 日本ウイルス学会
Event date： 2019.10.29 - 2019.10.31
Language：Japanese Presentation type：Poster presentation
Venue：東京（江戸川区）
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Isolation of hidden minor prion conformers from classical scrapie isolates in advanced protein misfolding cyclic amplification in the presence of arginine ethyl ester. International conference
Imamura M, Miyazawa K, Matsuura Y, Iwamaru Y, Kitamoto T, Mohri S, Takatsuki H, Mori T, Atarashi R
APPS2019 (Wako, Saitama) Asian Pacific Prion Symposium
Event date： 2019.10.3 - 2019.10.4
Language：English Presentation type：Poster presentation
Venue：Wako, Saitama
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Biological evidence that new scrapie strain emerges from the conformational rearrangement of the parental strain. International conference
Miyazawa K, Matsuura Y, Imamura M, Iwamaru Y
APPS2019 (Wako, Saitama) Asian Pacific Prion Symposium
Event date： 2019.10.3 - 2019.10.4
Language：English Presentation type：Poster presentation
Venue：Wako, Saitama
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Pentosan polysulfate induces latent prion infection in Fukuoka-1 strain-infected cells. International conference
Takatsuki H, Mori T, Imamura M, Atarashi R
APPS2019 (Wako, Saitama) Asian Pacific Prion Symposium
Event date： 2019.10.3 - 2019.10.4
Language：English Presentation type：Poster presentation
Venue：Wako, Saitama
Grant-in-Aid for Scientific Research 【 display / non-display 】
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食用動物等のプリオン病の病態機序およびヒトへの感染リスクの解明に関する研究
Grant number：23KA1004 2023.04 - 2027.03
厚生労働省 厚生科研 食品の安全確保推進研究事業
Authorship：Coinvestigator(s)
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定型牛海綿状脳症の起源の解明
Grant number：21K05938 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)
Authorship：Principal investigator
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GPIアンカー修飾はアルファシヌクレイノパチーの病原性・伝達性を促進するか？
Grant number：20K21579 2020.04 - 2023.03
独立行政法人日本学術振興会 科学研究費補助金 挑戦的研究(萌芽)
新 竜一郎、
Authorship：Coinvestigator(s)
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孤発性および遺伝性プリオン病におけるプリオン自発的生成機構の解明
Grant number：18K07393 2018.04 - 2021.03
科学研究費補助金 基盤研究(C)
Authorship：Principal investigator
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試験管内増幅法を用いた異常プリオン蛋白質の複製に関与する補因子の探索
Grant number：25460575 2013.04 - 2016.03
科学研究費補助金 基盤研究(C)
Authorship：Principal investigator