title: Suppression of the mTOR-raptor signaling pathway by the inhibitor of heat shock protein 90 geldanamycin.
abstract: Heat shock protein 90 (Hsp90) was co-immunoprecipitated with raptor, the binding partner of the mammalian target of rapamycin (mTOR) from HEK293 cells. Hsp90 was detected in the anti-raptor antibody immunoprecipitates prepared from the cell extract by immunoblot analysis using the anti-Hsp90 antibody, and the association of these two proteins was confirmed by immunoprecipitation from the cells co-expressing Hsp90 and raptor as epitope-tagged molecules. Geldanamycin, a potent inhibitor of Hsp90, disrupted the in vivo binding of Hsp90 to raptor without affecting the association of raptor and mTOR, and suppressed the phosphorylation by mTOR of the downstream translational regulators p70 S6 kinase (S6K) and eukaryotic initiation factor 4E-binding protein 1 (4E-BP1). The protein kinase activity of S6K as well as the phosphorylation of the substrate, 40S ribosomal protein S6, were lowered in the geldanamycin-treated cells. These results indicate that Hsp90 is involved in the regulation of protein translation by facilitating the phosphorylation reaction of 4E-BP1 and S6K catalyzed by the mTOR/raptor complex through the association with raptor, and that the mTOR signaling pathway is a novel target of geldanamycin.
authors.affiliation: Biosignal Research Center, Kobe University, Kobe 657-8501.
authors.forename: Goh
authors.initials: G
authors.lastname: Ohji
authors.forename: Sujuti
authors.initials: S
authors.lastname: Hidayat
authors.forename: Akio
authors.initials: A
authors.lastname: Nakashima
authors.forename: Chiharu
authors.initials: C
authors.lastname: Tokunaga
authors.forename: Noriko
authors.initials: N
authors.lastname: Oshiro
authors.forename: Ken-Ichi
authors.initials: K
authors.lastname: Yoshino
authors.forename: Koichi
authors.initials: K
authors.lastname: Yokono
authors.forename: Ushio
authors.initials: U
authors.lastname: Kikkawa
authors.forename: Kazuyoshi
authors.initials: K
authors.lastname: Yonezawa
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D016227:Benzoquinones / Q000494:pharmacology*; D002460:Cell Line; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D018841:HSP90 Heat-Shock Proteins / Q000037:antagonists & inhibitors*; D006801:Humans; D047468:Immunoprecipitation; D047029:Lactams, Macrocyclic / Q000494:pharmacology*; D008969:Molecular Sequence Data; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism*; D011506:Proteins / Q000378:metabolism*; D000076223:Regulatory-Associated Protein of mTOR; D015398:Signal Transduction; D058570:TOR Serine-Threonine Kinases
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D016227:Benzoquinones; D004791:Enzyme Inhibitors; D018841:HSP90 Heat-Shock Proteins; D047029:Lactams, Macrocyclic; D011506:Proteins; C463659:RPTOR protein, human; D000076223:Regulatory-Associated Protein of mTOR; D011494:Protein Kinases; C546842:MTOR protein, human; D058570:TOR Serine-Threonine Kinases; C001277:geldanamycin