九州大学 研究者情報
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池ノ内 順一(いけのうち じゅんいち) データ更新日:2023.11.27

教授 /  理学研究院 生物科学部門 情報生物学


主な研究テーマ
上皮細胞の細胞接着や細胞極性形成の分子メカニズムの解明
細胞膜と細胞骨格の相互作用の解明

キーワード:上皮細胞、タイトジャンクション、微絨毛、細胞極性、生体膜、細胞骨格
2002.04~2023.09.
研究業績
主要原著論文
1. Shigetomi K, Ono Y, Matsuzawa K, Ikenouchi J., Cholesterol-rich domain formation mediated by ZO proteins is essential for tight junction formation, Proc Natl Acad Sci U S A, 10.1073/pnas.2217561120., 120, 8, e2217561120, 2023.02, Tight junctions (TJs) are cell-adhesion structures responsible for the epithelial barrier. We reported that accumulation of cholesterol at the apical junctions is required for TJ formation [K. Shigetomi, Y. Ono, T. Inai, J. Ikenouchi, J. Cell Biol. 217, 2373–2381 (2018)]. However, it is unclear how cholesterol accumulates and informs TJ formation—and whether cholesterol enrichment precedes or follows the assembly of claudins in the first place. Here, we established an epithelial cell line (claudin-null cells) that lacks TJs by knocking out claudins. Despite the lack of TJs, cholesterol normally accumulated in the vicinity of the apical junctions. Assembly of claudins at TJs is thought to require binding to zonula occludens (ZO) proteins; however, a claudin mutant that cannot bind to ZO proteins still formed TJ strands. ZO proteins were however necessary for cholesterol accumulation at the apical junctions through their effect on the junctional actomyosin cytoskeleton. We propose that ZO proteins not only function as scaffolds for claudins but also promote TJ formation of cholesterol-rich membrane domains at apical junctions..
2. Yumiko Ono, Kenji Matsuzawa, Junichi Ikenouchi, mTORC2 suppresses cell death induced by hypo-osmotic stress by promoting sphingomyelin transport, The Journal of Cell Biology, 10.1083/jcb.202106160, 2022.01, Epithelial cells are constantly exposed to osmotic stress. The influx of water molecules into the cell in a hypo-osmotic environment increases plasma membrane tension as it rapidly expands. Therefore, the plasma membrane must be supplied with membrane lipids since expansion beyond its elastic limit will cause the cell to rupture. However, the molecular mechanism to maintain a constant plasma membrane tension is not known. In this study, we found that the apical membrane selectively expands when epithelial cells are exposed to hypo-osmotic stress. This requires the activation of mTORC2, which enhances the transport of secretory vesicles containing sphingomyelin, the major lipid of the apical membrane. We further show that the mTORC2-Rab35 axis plays an essential role in the defense against hypotonic stress by promoting the degradation of the actin cortex through the up-regulation of PI(4,5)P2 metabolism, which facilitates the apical tethering of sphingomyelin-loaded vesicles to relieve plasma membrane tension..
3. Yuma Cho, Daichi Haraguchi, Kenta Shigetomi, Kenji Matsuzawa, Seiichi Uchida, Junichi Ikenouchi, Tricellulin secures the epithelial barrier at tricellular junctions by interacting with actomyosin, The Journal of Cell Biology, 10.1083/jcb.202009037, 2022.01, The epithelial cell sheet functions as a barrier to prevent invasion of pathogens. It is necessary to eliminate intercellular gaps not only at bicellular junctions, but also at tricellular contacts, where three cells meet, to maintain epithelial barrier function. To that end, tight junctions between adjacent cells must associate as closely as possible, particularly at tricellular contacts. Tricellulin is an integral component of tricellular tight junctions (tTJs), but the molecular mechanism of its contribution to the epithelial barrier function remains unclear. In this study, we revealed that tricellulin contributes to barrier formation by regulating actomyosin organization at tricellular junctions. Furthermore, we identified α-catenin, which is thought to function only at adherens junctions, as a novel binding partner of tricellulin. α-catenin bridges tricellulin attachment to the bicellular actin cables that are anchored end-on at tricellular junctions. Thus, tricellulin mobilizes actomyosin contractility to close the lateral gap between the TJ strands of the three proximate cells that converge on tricellular junctions..
4. Matsuzawa, Kenji; Ohga, Hayato; Shigetomi, Kenta; Shiiya, Tomohiro; Hirashima, Masanori; Ikenouchi, Junichi, MAGIs regulate aPKC to enable balanced distribution of intercellular tension for epithelial sheet homeostasis, COMMUNICATIONS BIOLOGY, 10.1038/s42003-021-01874-z, 4, 1, 2021.03, [URL], Constriction of the apical plasma membrane is a hallmark of epithelial cells that underlies cell shape changes in tissue morphogenesis and maintenance of tissue integrity in homeostasis. Contractile force is exerted by a cortical actomyosin network that is anchored to the plasma membrane by the apical junctional complexes (AJC). In this study, we present evidence that MAGI proteins, structural components of AJC whose function remained unclear, regulate apical constriction of epithelial cells through the Par polarity proteins. We reveal that MAGIs are required to uniformly distribute Partitioning defective-3 (Par-3) at AJC of cells throughout the epithelial monolayer. MAGIs recruit ankyrin-repeat-, SH3-domain- and proline-rich-region-containing protein 2 (ASPP2) to AJC, which modulates Par-3-aPKC to antagonize ROCK-driven contractility. By coupling the adhesion machinery to the polarity proteins to regulate cellular contractility, we propose that MAGIs play essential and central roles in maintaining steady state intercellular tension throughout the epithelial cell sheet..
5. Aoki, Kana; Harada, Shota; Kawaji, Keita; Matsuzawa, Kenji; Uchida, Seiichi; Ikenouchi, Junichi, STIM-Orai1 signaling regulates fluidity of cytoplasm during membrane blebbing, NATURE COMMUNICATIONS, 10.1038/s41467-020-20826-5, 12, 1, 2021.01, [URL], The cytoplasm in mammalian cells is considered homogeneous. In this study, we report that the cytoplasmic fluidity is regulated in the blebbing cells; the cytoplasm of rapidly expanding membrane blebs is more disordered than the cytoplasm of retracting blebs. The increase of cytoplasmic fluidity in the expanding bleb is caused by a sharp rise in the calcium concentration. The STIM-Orai1 pathway regulates this rapid and restricted increase of calcium in the expanding blebs. Conversely, activated ERM protein binds to Orai1 to inhibit the store-operated calcium entry in retracting blebs, which results in decreased in cytoplasmic calcium, rapid reassembly of the actin cortex..
6. Shiomi R, Shigetomi K, Inai T, Sakai M, Junichi Ikenouchi, CaMKII regulates the strength of the epithelial barrier, SCIENTIFIC REPORTS, 10.1038/srep13262, 5, 2015.08.
7. 池ノ内 順一, 平田 愛美, 米村 重信, 梅田 真郷, Sphingomyelin clustering is essential for the formation of microvilli., Journal of Cell Science, 10.1242/jcs.122325., 126, 16, 3585-3592, 2013.08, Cellular architectures require regulated mechanisms to correctly localize the appropriate plasma membrane lipids and proteins. Microvilli are dynamic filamentous-actin-based protrusions of the plasma membrane that are found in the apical membrane of epithelial cells. However, it remains poorly understood how their formation is regulated. In the present study, we found that sphingomyelin clustering underlies the formation of microvilli. Clustering of sphingomyelin is required for the co-clustering of the sialomucin membrane protein podocalyxin-1 at microvilli. Podocalyxin-1 recruits ezrin/radixin/moesin (ERM)-binding phosphoprotein-50 (EBP50; also known as NHERF1), which recruits ERM proteins and phosphatidylinositol 4-phosphate 5-kinase β (PIP5Kβ). Thus, clustering of PIP5Kβ leads to local accumulation of phosphatidylinositol (4,5)-bisphosphate [PtdIns(4,5)P2], which enhances the accumulation of ERM family proteins and induces the formation of microvilli. The present study revealed novel interactions between sphingomyelin and the cytoskeletal proteins from which microvilli are formed, and it clarified the physiological importance of the chemical properties of sphingomyelin that facilitate cluster formation. .
主要総説, 論評, 解説, 書評, 報告書等
主要学会発表等
1. 池ノ内順一, Reciprocal Regulation of AJ and TJ During the Assembly of Apical Adhesion Complex, Gordon Research Conference "Cell Contact and Adhesion" 2019, 2019.06, There are many morphologically distinct membrane structures with different functions at the surface of epithelial cells. Among these, adherens junctions (AJ) and tight junctions (TJ) are responsible for the mechanical linkage of epithelial cells and epithelial barrier function, respectively. In the process of new cell–cell adhesion formation between two epithelial cells, such as after wounding, AJ form first and then TJ form on the apical side of AJ. This process is very complicated because AJ formation triggers drastic changes in the organization of actin cytoskeleton, the activity of Rho family of small GTPases, and the lipid composition of the plasma membrane, all of which are required for subsequent TJ formation. In this review, the authors focus on the relationship between AJ and TJ as a representative example of specialization of plasma membrane regions and introduce recent findings on how AJ formation promotes the subsequent formation of TJ..
2. 池ノ内 順一, 塩見 僚, 重富 健太, 上皮間葉転換における細胞膜脂質の質的変化の意義について, BMB2015(第38回日本分子生物学会年会、第88回日本生化学会大会 合同大会), 2015.12.
特許出願・取得
特許出願件数  1件
特許登録件数  0件
学会活動
所属学会名
日本分子生物学会
日本細胞生物学会
学協会役員等への就任
2020.05~2022.05, 日本細胞生物学会, 幹事.
2018.04~2020.04, 日本脂質生化学会, 評議員.
2017.04~2019.04, 日本生化学会, 評議員.
2018.06~2020.06, 日本細胞生物学会, 理事.
2010.04~2016.03, 日本細胞生物学会, 評議員.
学会大会・会議・シンポジウム等における役割
2015.12.03~2015.12.03, BMB2015(第38回日本分子生物学会年会、第88回日本生化学会大会 合同大会), 座長(Chairmanship).
学会誌・雑誌・著書の編集への参加状況
2018.01~2022.01, Tissue Barriers, 国際, 編集委員.
2015.06~2020.06, Scientific Reports, 国際, 編集委員.
2014.01~2016.01, The Journal of Biochemistry, 国際, 編集委員.
2013.01~2016.01, Cell Structure and Function, 国際, 編集委員.
受賞
花王科学賞, 公益財団法人 花王芸術・科学財団, 2022.06.
第12回柿内三郎記念奨励研究賞, 公益社団法人日本生化学会, 2015.12.
第7回井上リサーチアウォード, 井上科学振興財団, 2014.12.
科学技術分野の文部科学大臣表彰 若手科学者賞, 文部科学省, 2014.04.
研究資金
科学研究費補助金の採択状況(文部科学省、日本学術振興会)
2023年度~2024年度, 挑戦的研究(萌芽), 代表, 細胞膜構造形成における形質膜局所の秩序性変化の可視化.
2022年度~2024年度, 基盤研究(B), 代表, 上皮細胞の細胞膜構造形成におけるスフィンゴミエリンの機能解明.
2021年度~2022年度, 挑戦的研究(萌芽), 代表, 脂質結合タンパク質の改変による新たな脂質プローブの作出.
2019年度~2021年度, 基盤研究(B), 代表, 細胞膜構造の形成に関わる脂質の機能と細胞内輸送に関する研究.
2019年度~2020年度, 新学術領域研究, 代表, 数理モデルによる細胞膜ブレブの形成退縮機構の理解.
2017年度~2018年度, 新学術領域研究, 代表, 細胞膜ブレブの形成退縮に関わるシグナル伝達機構の解明.
2016年度~2017年度, 新学術領域研究, 代表, 微絨毛形成における細胞膜脂質の機能解析.
2015年度~2017年度, 基盤研究(C), 代表, 細胞膜のIdentityの構成的理解 .
2014年度~2015年度, 新学術領域研究, 代表, 細胞膜脂質が上皮管腔構造形成において果たす役割の解明.
2013年度~2016年度, 若手研究(A), 代表, 微絨毛形成におけるスフィンゴミエリンの機能解明.
2012年度~2014年度, 新学術領域研究, 代表, 細胞膜脂質が上皮管腔構造形成において果たす役割の解明.
2012年度~2015年度, 挑戦的萌芽研究, 代表, 細胞の脂質量を維持する仕組みの解明.
2009年度~2013年度, 若手研究(A), 代表, 細胞膜を構成する脂質分子の同定とその新規機能の解明.
競争的資金(受託研究を含む)の採択状況
2021年度~2023年度, 創発的研究支援事業(JST), 代表, 細胞質の区画化と流動性を制御する分子機構の解明.
2021年度~2022年度, AMED革新的先端研究開発支援事業 FORCE, 代表, ヒト浸潤癌における細胞膜の質的変化の検証と細胞膜を標的とした治療法開発.
2015年度~2018年度, 革新的先端研究開発支援事業 AMED-PRIME「画期的医薬品等の創出をめざす脂質の生理活性と機能の解明」, 代表, 上皮間葉転換に伴って変動する脂質の同定とその機能解析.
2012年度~2016年度, 戦略的創造研究推進事業 (文部科学省), 代表, 人工細胞作出に向けた人工脂質二重膜と生体膜の違いの解明.
2007年度~2011年度, 戦略的創造研究推進事業 (文部科学省), 代表, 細胞の極性形成に関わる膜ドメインの形成・維持機構の解明.
寄附金の受入状況
2009年度, 内藤財団, 内藤記念科学奨励金 「上皮細胞の細胞接着と細胞の極性形成維持機構の分子基盤の解明」.
2009年度, 内藤財団, 内藤財団 特定研究助成金 「上皮細胞の細胞膜ドメインを規定する脂質の探索」.
2010年度, 日本国際財団, 日本国際財団 研究助成金 「上皮細胞の細胞接着に関わる脂質分子の機能解析」.

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