Kyushu University Academic Staff Educational and Research Activities Database
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Takeshi Sekiguchi Last modified date:2019.05.24

Assistant Professor / Molecular Biology
Department of Molecular Biology
Faculty of Medical Sciences


Graduate School


E-Mail
Phone
092-642-6179
Fax
092-642-6176
Academic Degree
Ph.D.
Field of Specialization
Molecular biology, Biochemstry, Cell biology, Molecular ecology
Research
Research Interests
  • Elucidation of mechanisms of cell response against oxidative stress
    keyword : 8oxoGuanine, oxidative RNA
    2011.02~2018.03.
  • Elucidation of molecular mechanisms of cell growth and arrest in eukaryotic cells.
    keyword : cell cycle, GTP binding protein, GTR1/2、Rag A/B, Rag C/D, RCC1, Ran
    1997.04~2018.03Elucidation of molecular mechanisms of cell growth and arrest in eukaryotic cells..
  • Molecular ecology of carnivora
    keyword : species determination, sex determination, individual identification
    2007.10~2018.03.
  • Studies about the effect of fucoidan on cell.
    keyword : fucoidan
    2013.05~2018.03.
Academic Activities
Papers
1. Takeshi Sekiguchi, Nobuaki Furuno, Takashi Ishii, Eiji Hirose, Fumiko Sekiguchi, Yonggang Wang, and Hideki Kobayashi, RagA, an mTORC1 activator, interacts with a hedgehog signaling protein, WDR35/IFT121, Genes to Cells, doi.org/10.1111/gtc.12663, 24, 2, 151-161, 2019.02, [URL].
2. Takeshi Sekiguchi, Yoshiaki Kamada, Nobuaki Furuno, Minoru Funakoshi, Hideki Kobayashi, Amino acid residues required for Gtr1p-Gtr2p complex formation and its interactions with the Ego1p-Ego3p complex and TORC1 components in yeast, Genes to cells, 19, 6, 449-463, 2014.06, The yeast Ras-like GTPases Gtr1p and Gtr2p form a heterodimer, are implicated in the regulation of TOR complex 1 (TORC1), and play pivotal roles in cell growth. Gtr1p and Gtr2p bind Ego1p and Ego3p, which are tethered to the endosomal and vacuolar membranes where TORC1 functions are regulated through a relay of amino acid signaling interactions. The mechanisms by which Gtr1p and Gtr2p activate TORC1 remain obscure. We probed the interactions of the Gtr1p-Gtr2p complex with the Ego1p-Ego3p complex and TORC1 subunits. Mutations in the region (179-220 a.a.) following the nucleotide-binding region of Gtr1p and Gtr2p abrogated their mutual interaction and resulted in a loss in function, suggesting that complex formation between Gtr1p and Gtr2p was indispensable for TORC1 function. A modified yeast two-hybrid assay revealed that Gtr1p-Gtr2p complex formation is important for its interaction with the Ego1p-Ego3p complex. GTP-bound Gtr1p interacted with the region containing the HEAT repeats of Kog1p and the C-terminal region of Tco89p. The GTP-bound Gtr2p suppressed a Kog1p mutation. Our findings indicate that the interactions of the Gtr1p-Gtr2p complex with the Ego1p-Ego3p complex and TORC1 components Kog1p and Tco89p play a role in TORC1 function..
3. Takeshi Sekiguchi, Riyoko Itoh, Hiroshi Hayakawa, Mutsuo Sekiguchi, Elimination and utilization of oxidized Guanine nucleotides in the synthesis of RNA and its precursors., J Biol Chem. , doi: 10.1074/jbc.M112.418723. , 288, 12, 8128-8135, 2013.03.
4. Sekiguchi, T., Hayashi, N., Wang, Y., Kobayashi, H., Genetic evidence that Ras-like GTPases, Gtr1p and Gtr2p, are involved in epigenetic control of gene expression in Saccharomyces cerevisiae, Biochem Biophys Res Commun, 368, 3, 748-754, 2008.04.
5. Sekiguchi1,T., Hayano,T., Yanagida, M., Takahashi,N., Nishimoto,T., NOP132 is required for proper nucleolus localization of DEAD-box RNA helicase DDX47., Nucleic Acid Res., 34,4593-4608, 2006.09.
6. Sekiguchi, T., Iida, H., Fukumura, J. and Nishimoto T, Human DDX3Y, the Y-encoded isoform of RNA helicase DDX3, rescues a hamster temperature-sensitive ET24 mutant cell line with a DDX3X mutation., Exp. Cell. Res., 10.1016/j.yexcr.2004.07.005, 300, 1, 213-222, Vol.300 pp213-222, 2004.10.
7. Sekiguchi, T., Todaka Y., Wang YG., Hirose, E., Nakashima, N. and Nishimoto, T., A novel human nucleolar protein, Nop132, binds to the G proteins, RRAG A/C/D., J. Biol. Chem., 10.1074/jbc.M305935200, 279, 9, 8343-8350, Vol.279 pp8343-8350, 2004.01.
8. Sekiguchi, T., Hirose, E., Nakashima, N., Ii, M. and Nishimoto, T., Novel G proteins, Rag C and Rag D, interact with GTP-binding proteins Rag A and Rag B., J. Biol. Chem., 10.1074/jbc.M004389200, 276, 10, 7246-7257, Vol.276,No.10,pp.7246-7257, 2001.01.
9. T, Sekiguchi, T.Nishimoto and T. Hunter, Overexpression of D-type cyclins, E2F-1, SV40 large T antigen and HPV16 E7 rescue cell cycle arrest of tsBN462 cells caused by the CCG1/TAFII250 mutation, Oncogene., 10.1038/sj.onc.1202508, 18, 10, 1797-1806, Vol.18,pp.1797-1806, 1999.03.
10. Sekiguchi, T., T. Hunter, Induction of growth arrest and cell death by overexpression of the cyclin-Cdk inhibitor p21 in hamster BHK21 cells, Oncogene., Vol.16,pp.369-380, 1998.01.
11. Sekiguchi,T., Nohiro,Y., Nakamura,Y., Hisamoto,N.and T.Nishimoto., The human CCG1 gene, essential for progression of the G1 phase, encodes a 210-Kilodalton nuclear DNA-binding protein, Molecular and Cellular Biology., 11, 6, 3317-3325, Vol.11,pp.3317-3325, 1991.11.
12. Uchida,S., Sekiguchi,T., Nishitani,H., Miyauchi,K., Ohtsubo,M.and T.Nishimoto., Premature chromosome condensation is induced by a point mutation in the hamster RCC1 gene, Molecular and Cellular Biology., 10, 2, 577-584, Vol.10,pp.577-584, 1990.10.
13. Sekiguchi,T., Miyata,T.and T.Nishimoto., Molecular cloning of the cDNA of human X chromosomal gene (CCG1) which complements the temperature-sensitive G1 mutants, tsBN462 and ts13, of the BHK cell line, The EMBO Journal., 7, 6, 1683-1687, Vol.7,pp.1683-1687, 1988.01.
Presentations
1. RagA, a mTORC1 regulator, interacts with the WDR35 protein..
2. A role of S.cerevisae Gtr1p on toxic substance exclusion.
3. 関口 猛, Riyoko Itoh, Hiroshi Hayakawa, Mutsuo Sekiguchi, Elimination of oxidized nucleic acid, 第86回日本生化学会大会, 2013.09, During the de novo synthesis of guanine nucleotides, GMP is formed first, which is converted to GDP by guanylate kinase (GMK), an essential protein for E.coli. This enzyme hardly acts on an oxidized form of GMP (8-oxo-GMP), formed by the oxidation of GMP or by the cleavage of 8-oxo-GDP and 8-oxo-GTP by MutT protein. Although the formation of 8-oxo-GDP from 8-oxo-GMP is thus prevented, 8-oxo-GDP itself may be produced by the oxidation of GDP by ROS. The 8-oxo-GDP thus formed can be converted to 8-oxo-GTP, since nucleoside diphosphate kinase and adenylate kinase, both of which catalyze conversion of GDP to GTP, do not discriminate 8-oxo-GDP from normal GDP. The 8-oxo-GTP produced in this way and also by the oxidation of GTP can be used for RNA synthesis. This misincorporation is prevented by MutT protein, which has a potential to cleave 8-oxo-GTP as well as 8-oxo-GDP to 8-oxo-GMP. When 14C-labeled 8-oxo-GTP was applied to CaCl2-permeabilized cells of mutT- mutant strain, it could be incorporated into RNA at 4% of the rate for GTP. Escherichia coli cells appear to possess mechanisms to prevent misincorporation of 8-oxo-Gua into RNA..
4. Analysis of fate of guanine nucleotide exogenously introduced into HeLa cells..
5. Interaction between Gtr1-Gtr2 and components of Tor complex1.
6. Analysis of Gtr1-Gtr2 complex on TOR signal transduction pathway..
7. Characterization of Gtr1/2 small G proteins..
8. Protein phosphorylation of RCC1, a RanGEF.
9. A study on the possible function of S23N GTR2 (GDP form).
Membership in Academic Society
  • The Japanese biochemical society
  • The protein society
  • The Genetics Society of Japan
  • The Mammalogical Society of Japan
  • American society for biochemistry and molecular biology
  • Japanese cancer association
  • The molecular biology society of Japan
Social
Professional and Outreach Activities
2007,March, Present my research for JST-Kyushu University joint seeds meeting in Tokyo..