研究内容
膜脂質と脂肪滴について分子細胞生物学的な手法で研究しています。凍結割断レプリカ法という独自の電子顕微鏡技術を持つことが強みです。
(1) 膜脂質のナノ分布解析
生体膜の脂質二重層には千種類以上の脂質が存在し、多種多様な現象に関わります。しかし①数µm/secの速さで動く二次元流動性を止め、脂質二重層を安定に保つ化学的方法がないこと、②脂質の多くは分子量1,000以下の低分子で、蛍光基付加などの化学修飾で性質が容易に変化すること、③遺伝子で直接コードされないこと、などの理由から、脂質分子そのものを可視化して解析する方法は存在しないと言っても過言ではなく、タンパク質に比べて解析が大きく立ち遅れています。私たちは生きている細胞を瞬時に凍結し、生体膜を物理的に安定な状態に保持できる凍結割断レプリカ法を用いて、膜脂質の分布と動態をナノメートルのレベルで解析することに成功しました。この方法では生体膜の２層を明確に区別できるため、脂質分布の非対称性を解析することもできます。オートファジーの際に現れる隔離膜はどのように作られるのかなど、これまでの方法では解析が難しい現象について研究を進めています。
(2) 脂肪滴機能の解析
脂肪滴は脂肪細胞だけでなく、ほとんどの細胞に存在し、脂肪貯蔵に留まらない多彩な機能を持つオルガネラであることが分かってきました。私たちは脂肪滴の表層が特殊なリン脂質一重層で作られることを見出し、タンパク質分解の場としての働きや、タンパク質をリクルートして活性化する機能を持つことなどを明らかにしてきました。最近の研究では、核内に形成される脂肪滴に注目し、その表層が主要なリン脂質であるホスファチジルコリン合成酵素の制御に決定的な役割を果たすことを解明しました。核内脂肪滴にはまだ多くの謎が残されており、生理的機能だけでなく、疾病との関係についても研究を行っています。
研究内容その他に関するお問い合わせは藤本（t.fujimoto.xl[at]juntendo.ac.jp）までお願いします。
業績
研究業績 (2016〜)
2025
Tsuji T, Hasegawa J, Sasaki T, Fujimoto T*. Definition of phosphatidylinositol 4,5-bisphosphate
distribution by freeze-fracture replica labeling. J Cell Biol 224, e202311067, 2025. PubMed
2024
Fujimoto T*. Nuclear lipid droplet: guardian of nuclear membrane lipid homeostasis? Curr Op Cell Biol,88:102370, 2024. PubMed
2023
2022
Fujimoto T*. Nuclear lipid droplets—how are they different from their cytoplasmic siblings? J Cell Sci 135, jcs259253, 2022. PubMed
Mioka T, Tian G, Wang S, Tsuji T, Kishimoto T, Fujimoto T, Tanaka K. A micron-scale protein-depleted plasma membrane domain could be generated in phosphatidylserine-deficient yeast cells. J Cell Sci, jcs256529, 2022. PubMed
2021
Orii M, Tsuji T, Ogasawara Y, Fujimoto T*. Transmembrane phospholipid translocation mediated by Atg9 is involved in autophagosome formation. J Cell Biol 220, e202009194, 2021. PubMed プレスリリース 科学新聞に掲載された記事
Soltysik K, Ohsaki Y, Tatematsu T, Cheng J, Maeda A, Morita S, Fujimoto T*. Nuclear lipid droplets form in the inner nuclear membrane in a seipin-independent manner. J Cell Biol 220, e202005026, 2021. PubMed プレスリリース JCB Spotlight記事
2020
Matoba K, Kotani T, Tsutsumi A, Tsuji T, Mori T, Noshiro D, Sugita Y, Nomura N, Iwata S, Ohsumi Y, Fujimoto T, Nakatogawa H, Kikkawa M, Noda NN*. A lipid scramblase mediates autophagosomal membrane expansion. Nat Struct Mol Biol 27, 1185-93, 2020. PubMed プレスリリース
Ogasawara Y, Chang J, Tatematsu T, Uchida M, Murase O, Yoshikawa S, Ohsaki Y, Fujimoto T*. Long-term autophagy is sustained by activation of CCTβ3 on lipid droplets. Nat Commun 11, 4480, 2020. PubMed プレスリリース
Ogasawara Y, Tsuji T, Fujimoto T*. Multifarious roles of lipid droplets in autophagy – Target, product, and what else? Semin Cell Dev Biol 108, 47-54, 2020. PubMed
Masuda T, Hirose H, Baba K, Walrant A, Sagan S, Inagaki N, Fujimoto T, Futaki S*. An artificial amphiphilic peptide promotes endocytic uptake by inducing membrane curvature. Bioconjug Chem 31, 1161-1165, 2020. PubMed
Schäfer J, Schessner JP, Tsuju T, Funaya C, Bircham PW, Schaeff K, Ruffini G, Fujimoto T, Schuck S*. ESCRT machinery mediates selective microautophagy of endoplasmic reticulum. EMBO J 39, e102586, 2020. PubMed
Shirakawa R, Goto-Ito S, Goto K, Wakayama S, Kubo H, Sakata N, Trinh DA, Yamagata A, Sato Y, Masumoto H, Cheng J, Fujimoto T, Fukai S, Horiuchi H*. A SNARE geranylgeranyltransferase essential for the organization of the Golgi apparatus. EMBO J 39, e104120, 2020. PubMed
Yamaguchi T, Fujimoto T, Takahashi T*. Method for efficient observation of caveolin-1 in plasma membrane by microscopy imaging analysis. Methods Mol Biol 2169, 43-52, 2020. PubMed
2019
Sołtysik K, Ohsaki Y*, Tatematsu T, Cheng J, Fujimoto T*. Nuclear lipid droplets derive from a lipoprotein precursor and regulate phosphatidylcholine synthesis. Nat Commun 10, 473, 2019. PubMed プレスリリース
Tsuji T, Cheng J, Tatematsu T, Ebata A, Kamikawa H, Fujita A, Gyobu S, Segawa K, Arai H, Taguchi T, Nagata S, Fujimoto T*. Predominant localization of phosphatidylserine at the cytoplasmic leaflet of the ER, and its TMEM16K-dependent redistribution. Proc Natl Acad Sci USA 116, 13368-13373, 2019. PubMed プレスリリース
Tsuji T, Takatori S, Fujimoto T*. Definition of phosphoinositide distribution in the nanoscale. Curr Op Cell Biol 57, 33-39, 2019. PubMed
Kawai T, Miyata H, Nakanishi H, Sakata S, Morioka S, Sasaki J, Watanabe M, Sakimura K, Fujimoto T, Sasaki T, Ikawa M, Okamura Y*. Polarized PtdIns(4,5)P2 distribution mediated by a voltage-sensing phosphatase (VSP) regulates sperm motility. Proc Natl Acad Sci USA 116, 26020-26026, 2019. PubMed
Yamaguchi T, Hayashi M, Ida L, Yamamoto M, Lu C, Kajino T, Cheng J, Nakatochi M, Isomura H, Suzuki M, Fujimoto T, Takahashi T*. ROR1–CAVIN3 interaction is required for caveolae-dependent endocytosis and prosurvival signaling in lung adenocarcinoma. Oncogene 38, 5142-5157, 2019. PubMed
2018
Tsuji T, Fujimoto T*. Lipids and lipid domains in the yeast vacuole. Biochem Soc Trans 46, 1047-1054, 2018. PubMed
Tsuji T, Fujita A, Fujimoto T*. Immunoelectron microscopy of gangliosides. Methods Mol Biol 1804, 231-239, 2018. PubMed
Sobol M, Kalendová A, Yildirim S, Kalasová I, Fáberová V, Vrkoslav V, Philimonenko V, Marášek P, Pastorek L, Čapek M, Lubovská Z, Uličná L, Tsuji T, Lísa M, Cvačka J, Fujimoto T, Hozak P*. Nuclear phosphatidylinositol 4,5-bisphosphate islets contribute to efficient RNA polymerase II-dependent transcription. J Cell Sci 131, jcs.211094, 2018. PubMed
Kimura H, Arasaki K, Ohsaki Y, Fujimoto T, Tagaya M*. Syntaxin 17 promotes lipid droplet formation by regulating the distribution of acyl-CoA synthetase 3. J Lipid Res 59, 805-819, 2018. PubMed
Yang L, Wang L, Ma J, Yang G, Cui S, Geng T, Mordue D, Fujimoto T, Cheng G, You F, Lin R, Fikrig E, Wang P*. UBXN3B positively regulates STING mediated antiviral immune responses. Nat Commun 9, 2329, 2018. PubMed
Sugo M, Kimura H, Arasaki K, Amemiya T, Hirota N, Dohmae N, Imai Y, Inoshita T, Shiba-Fukushima K, Hattori N, Fujimoto T, Wakana Y, Inoue H, Tagaya M*. Syntaxin 17 regulates the localization and function of PGAM5 in mitochondrial division and mitophagy. EMBO J 37, e98899, 2018. PubMed
2017
Tsuji T, Fujimoto M, Tatematsu T, Cheng J, Orii M, Takatori S, Fujimoto T*. Niemann-Pick type C proteins promote microautophagy by expanding raft-like membrane domains in the yeast vacuole. eLife 6, e25960, 2017. PubMed プレスリリース
Imai N, Suzuki M, Ishizu Y, Honda T, Hayashi K, Ishigami M, Hirooka Y, Ishihara T, Goto H, Fujimoto T*. Hepatocyte-specific depletion of ubiquitin regulatory X domain containing protein 8 (UBXD8) accelerates fibrosis in a mouse non-alcoholic steatohepatitis model. Histochem Cell Biol 148, 219-227, 2017. PubMed
Tsuji T, Fujimoto T*. Freeze-fracture-etching electron microscopy for facile analysis of yeast ultrastructure. Bio Protoc 7, e2556, 2017. Link
Aktar S, Takatori S, Tsuji T, Ohsaki Y, Cheng J, Fujimoto T*. A new electron microscopic method to observe the distribution of phosphatidylinositol 3,4-bisphosphate. Acta Histochem Cytochem 50, 141-147, 2017. PubMed
Ohsaki Y, Sołtysik K, Fujimoto, T*. The lipid droplet and the endoplasmic reticulum. Adv Exp Med Biol 997, 111-120, 2017. PubMed
Fujimoto T, Parmryd, I*. Interleaflet coupling, pinning and leaflet asymmetry – major players in plasma membrane nanodomain formation. Frontier Cell Dev Biol 4, 155, 2017. PubMed
Oku M, Maeda Y, Kagohashi Y, Kondo T, Yamada M, Fujimoto T, Sakai Y*. Evidence for ESCRT- and clathrin-dependent microautophagy. J Cell Biol 216, 3263-3274, 2017. PubMed
Takabe W, Urano Y, Vo D-K H, Shibuya K, Tanno M, Kitagishi H, Fujimoto T, Noguchi N*. Esterification of 24(S)-hydroxycholesterol induces formation of atypical lipid droplet-like structures, leading to neuronal cell death. J Lipid Res 57, 2005-2014, 2016. PubMed
2016
Ohsaki Y, Kawai T, Yoshikawa Y, Cheng J, Jokitalo E, Fujimoto T*. PML isoform II plays a critical role in nuclear lipid droplet formation. J Cell Biol 212, 29-38, 2016. PubMed
Takatori S, Tatematsu T, Cheng J, Matsumoto J, Akano T, Fujimoto T*. Phosphatidylinositol 3,5-bisphosphate-rich membrane domains in endosomes and lysosomes. Traffic 17, 154-167, 2016. PubMed
Takatori S, Fujimoto T*. A novel imaging method revealed phosphatidylinositol 3,5-bisphosphate-rich domains in the endosome/lysosome membrane. Commun Integr Biol 9, e1145319, 2016. PubMed
Yamaguchi T, Lu C, Yanagisawa K, Can Lu, Usukura J, Cheng J, Hotta N, Shimada Y, Ida R, Isomura H, Suzuki M, Fujimoto T, Takahashi T*. ROR1 sustains caveolae and survival signaling as a scaffold of cavin-1 and caveolin-1. Nat Commun 7, 10060, 2016. PubMed
Makino A, Hullin-Matsuda F, Murate M, Abe M, Tomishige N, Fukuda M, Yamashita S, Fujimoto T, Vidal H, Lagarde M, Delton-Vandenbroucke I, Kobayashi T*. Acute accumulation of free cholesterol induces the degradation of perilipin 2 and Rab18-dependent fusion of ER and lipid droplets in cultured human hepatocytes. Mol Biol Cell 27, 3293-3304, 2016. PubMed