Kyushu University Academic Staff Educational and Research Activities Database
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Fujimoto Keiko Last modified date:2023.11.28

Assistant Professor / Division of Molecular Bioinformatics
Department of Pharmaceutical Health Care and Sciences
Faculty of Pharmaceutical Sciences

Graduate School
Undergraduate School

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 Reseacher Profiling Tool Kyushu University Pure
Academic Degree
Master's degree
Country of degree conferring institution (Overseas)
Field of Specialization
Cell biology
Total Priod of education and research career in the foreign country
Research Interests
  • Formation and maintenance of lysosome
    keyword : lysosome, endosome, small GTPase, membrane trafficking
  • Novel in vitro screening system of phospholipidosis
    keyword : phospholipidosis, lysosome, screening system, drug side effect
  • Inhibitory mechanism of melanin production
    keyword : whitening, melanine, melanosome, lysosome
  • Molecular mechanism of protein turnover
    keyword : autophagy, proteasome, endocytosis, lysosome
  • Molecular mechanisms of formation and maintenance of endosomes and Lysosomes by Rab proteins
    keyword : small GTPase, Rab proteins, Lysosome, Endosome, Membrane trafficking
  • Molecular mechanisms of formation of autophagosomes
    keyword : Autophagy, LC3, Lysosome
  • Molecular mechanisms of phospholipidosis
    keyword : Phospholipidosis, Lysosome, Membrane trafficking
  • Molecular mechanisms of intracellular transport and localization of trans-Golgi network resident protein TGN46
    keyword : TGN46, Lysosome, Endosome, ESCRT
Academic Activities
1. 藤本 景子,井田 広顕,廣田 有子,石谷 雅樹,天野 潤,田中 嘉孝, Intracellular Dynamics and Fate of a Humanized Anti-Interleukin-6 Receptor Monoclonal Antibody, Tocilizumab., Molecular Pharmacology, 10.1124, 88, 4, 660-675, 2015.10, Tocilizumab (TCZ), a humanized anti-interleukin-6 (IL-6) receptor (IL-6R) monoclonal antibody, abrogates signal transducer protein gp130-mediated IL-6 signaling by competitively inhibiting the binding of IL-6 to the receptor, and shows clinical efficacy in autoimmune and inflammatory diseases. Despite accumulating evidence for therapeutic efficacy, the behavior and fate of TCZ at the cellular level remain largely unknown. To address this, we evaluated the endocytosis and intracellular trafficking of IL-6R in HeLa cells. The results of our study provide evidence that IL-6R is constitutively internalized from the cell surface by ligand or TCZ binding and the expression of gp130 in an independent manner and is targeted via endosomes without being significantly directed to the recycling pathway to, and degraded in, lysosomes. Furthermore, the cytoplasmic tail of IL-6R is required for constitutive endocytosis of the receptor, which is mediated by the clathrin and AP-2 complex. We further demonstrate that FcRn, whose function is to regulate the serum persistence of IgG, is confined primarily to early/recycling endosomes and rapidly transits between these compartments and late endosomes/lysosomes without being degraded. Importantly, the expression of FcRn induces the segregation of TCZ from IL-6R, resulting in extensive colocalization of TCZ and FcRn in IL-6R-depleted endosomal compartments. Collectively, our results suggest that FcRn can accelerate the retrieval of the internalized TCZ, not only from endosomes but also from lysosomes. Our findings provide new insight into the mechanism by which the antibody internalized into cells is rescued from lysosomal degradation and into how its serum levels are maintained..
2. Hideaki Fujita, Keiko Fujimoto, Kenzo Tokunaga, and Yoshitaka Tanaka, Intracellular logistics of BST-2/tetherin, Current HIV Research, in press, 2012.08.
1. Riham Amen,Yoshitaka Tanaka,Yuko Hirota,Yuu Miyauchi,Yuji Ishii,Keiko Fujimoto, A proteomic analysis of integral and associated lysosomal membrane proteins, 第42回日本分子生物学会年会, 2019.12.
2. Keiko Fujimoto,Ryo Tadakuma,Chiaki Tanaka,Yuko Hirota,Yuu Miyauchi,Yuji Ishii,Yoshitaka Tanaka., Papuamine prevents the fusion between autophagosomes and lysosomes by inhibiting the maturation of autophagosomes., Experimental Biology 2019, 2019.04.
Membership in Academic Society
  • The Molecular Biology Society of Japan
  • Japan Society for Cell Biology
  • The Japanese Biochemical Society