title: PDMP, a ceramide analogue, acts as an inhibitor of mTORC1 by inducing its translocation from lysosome to endoplasmic reticulum.
abstract: Mammalian or mechanistic target of rapamycin complex 1 (mTORC1) is a master regulator of cell growth, metabolism, and cell differentiation. Recent studies have revealed that the recruitment of mTORC1 to lysosomes is essential for its activation. The ceramide analogue 1-phenyl-2-decanoylamino-3-morpholino-1-propanol (PDMP), a well known glycosphingolipid synthesis inhibitor, also affects the structures and functions of various organelles, including lysosomes and endoplasmic reticulum (ER). We investigated whether PDMP regulates the mTORC1 activity through its effects on organellar behavior. PDMP induced the translocation of mTORC1 from late endosomes/lysosomes, leading to the dissociation of mTORC1 from its activator Rheb in MC3T3-E1 cells. Surprisingly, we found mTORC1 translocation to the ER upon PDMP treatment. This effect of PDMP was independent of its action as the inhibitor, since two stereoisomers of PDMP, with and without the inhibitor activity, showed essentially the same effect. We confirmed that PDMP inhibits the mTORC1 activity based on the decrease in the phosphorylation of ribosomal S6 kinase, a downstream target of mTORC1, and the increase in LC3 puncta, reflecting autophagosome formation. Furthermore, PDMP inhibited the mTORC1-dependent osteoblastic cell proliferation and differentiation of MC3T3-E1 cells. Accordingly, the present results reveal a novel mechanism of PDMP, which inhibits the mTORC1 activity by inducing the translocation of mTOR from lysosomes to the ER.
authors.affiliation: Department of Periodontology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan; Research Fellow of the Japan Society for the Promotion of Science (JSPS), 5-3-1 Kojimachi, Chiyoda-ku, Tokyo 102-0083, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Ode
authors.affiliation: Department of Biochemistry, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan.
authors.forename: Katarzyna A
authors.initials: KA
authors.lastname: Podyma-Inoue
authors.affiliation: Department of Biochemistry, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan.
authors.forename: Kazue
authors.initials: K
authors.lastname: Terasawa
authors.affiliation: Division of Glycopathology, Institute of Molecular Biomembrane and Glycobiology, Tohoku Medical and Pharmaceutical University, 4-4-1, Komatsushima, Aoba-ku, Sendai, Miyagi 981-8558, Japan.
authors.forename: Jin-Ichi
authors.initials: JI
authors.lastname: Inokuchi
authors.affiliation: Lipid Biology Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan; CNRS, UMR 7213, University of Strasbourg, 67401 Illkirch, France.
authors.forename: Toshihide
authors.initials: T
authors.lastname: Kobayashi
authors.affiliation: Department of Biochemistry, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan.
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Watabe
authors.affiliation: Department of Periodontology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan.
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Izumi
authors.affiliation: Department of Biochemistry, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan. Electronic address: m.yokoyama.bch@tmd.ac.jp.
authors.forename: Miki
authors.initials: M
authors.lastname: Hara-Yokoyama
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D001343:Autophagy / Q000187:drug effects*; D002454:Cell Differentiation / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D002518:Ceramides / Q000737:chemistry / Q000494:pharmacology; D004721:Endoplasmic Reticulum / Q000187:drug effects* / Q000378:metabolism; D011992:Endosomes / Q000187:drug effects / Q000378:metabolism; D008247:Lysosomes / Q000187:drug effects* / Q000378:metabolism; D000076222:Mechanistic Target of Rapamycin Complex 1; D051379:Mice; D009025:Morpholines / Q000494:pharmacology*; D046912:Multiprotein Complexes / Q000037:antagonists & inhibitors / Q000378:metabolism*; D021381:Protein Transport; D058570:TOR Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*
chemical_list: D002518:Ceramides; D009025:Morpholines; D046912:Multiprotein Complexes; C033110:RV 538; D000076222:Mechanistic Target of Rapamycin Complex 1; D058570:TOR Serine-Threonine Kinases
keywords: ER; Lysosome; Osteoblast; PDMP; Subcellular localization; mTOR