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Iketani Masumi

    Biological Process of Aging　Researcher
Last Updated :2025/04/09

Researcher Information

URL

Research funding number

  • 60644359

J-Global ID

Research Areas

  • Life sciences / Neuroscience - general

Academic & Professional Experience

  • 2014/04 - Today  東京都健康長寿医療センター研究所
  • 2013  Yokohama City University医学(系)研究科(研究院)その他

Association Memberships

  • 日本分子状水素医学生物学会   日本基礎老化学会   日本分子生物学会   

Published Papers

Books etc

  • Physiological roles of LOTUS, an endogenous Nogo receptor antagonist, in lateral olfactory tract formation
    Masumi Iketani; Yuji Kurihara; Yasufumi Sato; Yoshio Goshima; Kohtaro Takei (Joint workJikkenigaku，vol.30 No.3 Feb)Yodosha 2012/02

Conference Activities & Talks

  • Axonal branching in lateral olfactory tract is regulated by LOTUS, an endogenous Nogo receptor antagonist  [Not invited]
    Iketani M; Kurihara Y; Sakakibara Y; Goshima Y; Takei K
    International Society for Neurochemistry-American Society for Neurochemistry 24th Biennial joint meeting  2013/04

MISC

Industrial Property Rights

Research Grants & Projects

  • 日本学術振興会：科学研究費助成事業
    Date (from‐to) : 2024/04 -2027/03 
    Author : 池谷 真澄
  • 日本学術振興会：科学研究費助成事業
    Date (from‐to) : 2021/04 -2024/03 
    Author : 池谷 真澄
     
    水素分子(H2)には抗酸化・抗炎症効果による疾患改善効果・予防効果があることが知られているが、その作用機序は未解明な部分が多い。我々は分子メカニズムの一端として、神経芽細胞にH2を１時間与すると一過的なリン脂質構成や代謝変化、酸化ストレスの発生等を誘導し、エンドソーム輸送の遅延が起こることを見いだし、H2投与により脂質膜構造と機能が変化したと推察した。我々はH2に曝されることによって起こる脂質変化・エンドソーム変化と疾患改善効果・予防効果の分子メカニズムの関係性について明らかにし、この研究成果により、H2の最適投与法を予測する為の基礎確立を本研究の目的としている。吸入麻酔薬は、脂質膜構造を変化させて麻酔効果を発揮すると考えられているが、H2と同じく直接的な作用分子に関しては不明な部分が多い。吸入麻酔薬のセボフルランはマウスなどの齧歯類の新生仔の脳において細胞死の一種であるアポトーシスを引き起こすが、0.5~1.3%濃度のH2の同時吸引によってそのアポトーシスが抑制されることが知られている。そこで、我々はH2とセボフルランの作用機序に相互連関があると考え、セボフルランによる脳細胞のアポトーシスに対するH2の影響を、新生仔マウスを用いて検証した。H2濃度を1~16%までふって新生仔マウスに投与したところ1~8%濃度でセボフルランによるアポトーシスを抑制し、16%では抑制効果を得られなかった。このことからH2ガスの最適投与濃度は1~8%である可能性が示唆された。また、セボフルランによるアポトーシスは脳梁膨大後部皮質で顕著であるが、アポトーシスを起こした細胞の大部分は神経幹細胞であることが分かり、Ｈ２によりアポトーシスが抑制されていた。更にアポトーシスに関わる様々な分子が水素により抑制されていることが明らかになってきている。
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2020/04 -2023/03 
    Author : Ohsawa Ikuroh
     
    Culturing neuroblastoma cells in the presence of hydrogen transiently increased certain phospholipids and broadly inhibited energy metabolic pathways. Simultaneously elevated oxidative stress may elicit an adaptive response in the cells. Hydrogen gas inhalation inhibited neural stem cell death in the brains of juvenile mice induced by anesthetic gas inhalation. c-Jun activation was inhibited. A single administration of hydrogen water to a mouse model of colitis for several days alleviated the pathological condition and inhibited the decrease of regulatory T cells in the small intestinal Peyer's patches. Furthermore, presentation of food antigens to dendritic cells was also inhibited, suggesting that hydrogen water contributes to the homeostasis of the intestinal immune system. In clinical studies, we have already completed safety studies of hydrogen gas inhalation therapy in several patients with acute aortic dissection.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2018/04 -2021/03 
    Author : Iketani Masumi
     
    Molecular hydrogen (H2) is known to act as an antioxidant and anti-inflammatory agent in the body, however, the mechanism of action remains unclear. In this study, we found that exposure of cells to H2 for only one hour changed the phospholipids that constitute the cell membrane. The phospholipids, which are known to function in the cellular organelles mitochondria and endosomes, were found to increase. Each of these is a cell organelle that is closely related to disease. We examined for changes in mitochondria-related metabolism, and found that many metabolites decreased within 1 hour of exposure to H2, indicating that transient oxidative stress was induced. We also examined endosomes and found that endosomal transport was delayed.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2016/04 -2018/03 
    Author : Iketani Masumi
     
    Molecular hydrogen (H2) functions as an antioxidant and anti-inflammatory agent in various diseases. However, the molecular mechanism is largely unknown. In this study, we focused on inflammatory response and oxidative stress response to elucidate the mechanism of H2 function. After administration of H2-dissolved water (HW) containing with a feeding needle in mice, the H2 concentration in the liver was immediately elevated. Moreover, we showed that preadministration of HW suppresses lipopolysaccharide (LPS)-induced endotoxin shock. Drinking HW for 3 days before LPS injection prolonged survival in a mouse model of sepsis. Moreover, preadministration of HW enhanced LPS-induced expression of heme oxyganase-1 in hepatocyte in the liver. Therefore, it was speculated that the target of H2 is a hepatocyte of the liver. Moreover, HW is likely to trigger adaptive responses against oxidative stress in the liver.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2015/04 -2018/03 
    Author : Ohsawa Ikuroh; IKETANI Masumi
     
    We applied stimulated emission depletion imaging with subdiffraction resolution to submitochondrial structures. Their shapes depend on both a cell’s type and its physiological state. Staining with a cationic fluorescent dye, TMRM, unveiled intriguing details of lamellar structure, consisting of rapidly changeable, curtain-like formations. The TMRM-positive structure colocalized with neither protein in the matrix nor on the outer membrane, but partially localized with the nucleoid. Suppression of a component in the mitochondrial contact site disrupted the lamellar TMRM-positive structure. Uncoupling of the oxidative phosphorylation system released TMRM from the inner membrane without any alteration in the matrix structure. The approach presented here provides novel insights into the in vivo nature of submitochondrial structures, and can be used for further functional investigations of these complex structures.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2013/04 -2015/03 
    Author : IKETANI Masumi
     
    Previously, we identified LOT usher substance (LOTUS) as an endogenous Nogo receptor-1 (NgR1) antagonist and found that LOTUS contributes to formation of LOT axonal bundle through its antagonistic action towards NgR1 function. The NgR1 is a receptor of axonal outgrowth inhibitors such as Nogo. We examined in vivo phenotypes in the axonal branching in LOT of LOTUS-KO and/or NgR1-KO mice. The collateral branches of LOT were increased in LOTUS-KO mice, whereas the collateral branches were decreased in NgR1-KO mice. Moreover, the abnormal increase of axonal branching seen in LOTUS-KO mice was rescued in double mutant of LOTUS- and NgR1-KO mice. These findings suggest that Nogo-A and NgR1 interaction may contribute to axonal branching in LOT development. Thus, it is considered that LOT formation is developmentally controlled by Nogo-A induction and down-regulation of the antagonistic action towards Nogo-NgR1 signaling by LOTUS.
  • 日本学術振興会：科学研究費助成事業
    Date (from‐to) : 2010 -2011 
    Author : 池谷 真澄
     
    本研究ではLOTUSの胎生期脳における生理機能を明らかにする目的でlotus及びngrl遺伝子欠損マウスを作製し、LOT形成に関わる機能解析を行った。1年目の研究で、まずLOTUS、Nogo、NgR1が三者ともLOTに存在していること、次にLOTUSは内在性のNgR1アンタゴニストとしてLOTの神経束形成に寄与することを明らかにした。 Nogoは胎生期の末梢神経系の軸索分枝を誘発するという報告がある(Marija M et al. Development 137,2539-2550,2010)。また、LOTは軸索伸長後胎生14日目以降で軸索分枝が起こることが知られている。そこで軸索分枝が進んだ胎生18日目のlotus-KOマウスのLOTをDiIによって可視化して観察したところ、野生型のマウスに比して軸索側枝の増加が観察された。また、ngrl-KOマウスにおいては野生型のマウスより軸索側枝が減少した。更に、lotusとngrlのダブル-KOマウスの軸索側枝はngrl-KOマウスと同程度にまで減少する傾向があった。これらのことからLOTUSによるNgR1の機能制御が軸索側枝形成の調節に関与することが示唆された。LOTUS、Nogo、NgR1はLOTに予め準備され、LOTの軸索束が形成されるまではLOTUSによってNogoの作用は抑制されているが、側枝形成期になるとLOTUSによるNogo作用の抑制が解除されて軸索側枝が形成されるとする仮説を提唱するに至った。 2年間の研究で、LOTUSがNgR1の内在性のアンタゴニストとして作用し、LOTの神経束形成と軸索側枝形成における生理機能も明らかにした。

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