title: USP15 attenuates IGF-I signaling by antagonizing Nedd4-induced IRS-2 ubiquitination.
abstract: Insulin receptor substrates (IRSs) are phosphorylated by IGF-I receptor tyrosine kinase in a ligand-dependent manner. In turn, they bind to and activate effector proteins such as PI3K, leading to various cell responses including cell proliferation. We had reported that ubiquitin ligase Nedd4 induces mono-ubiquitination of IRS-2, thereby enhancing IRS-2 tyrosine phosphorylation, leading to increased IGF signaling and mitogenic activity. Here we show that ubiquitin-specific protease 15 (USP15) antagonizes the effect of Nedd4 on IRS-2. We identified USP15 as a protein that preferentially bound to IRS-2 when IRS-2 was conjugated with ubiquitin. In HEK293 cells, Nedd4 overexpression induced IRS-2 ubiquitination, which was decreased by USP15 co-expression while increased by USP15 knockdown. Nedd4 overexpression enhanced IGF-I-dependent IRS-2 tyrosine phosphorylation, and USP15 co-expression suppressed it. Conversely, USP15 knockdown increased IRS-2 tyrosine phosphorylation and downstream signaling in prostate cancer PC-3 cells. We concluded that USP15 attenuates IGF-I signaling by antagonizing Nedd4-induced IRS-2 ubiquitination.
authors.affiliation: Department of Medical Science, Graduate School of Medicine, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima City, Hiroshima, 734-8553, Japan; Cell Biology Unit, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama, 226-8501, Japan.
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Fukushima
authors.affiliation: Laboratory of Protein Metabolism, Tokyo Metropolitan Institute of Medical Science, 2-1-6 Kamikitazawa, Setagaya-ku, Tokyo, 156-8506, Japan.
authors.forename: Hidehito
authors.initials: H
authors.lastname: Yoshihara
authors.affiliation: Department of Animal Sciences, Graduate School of Agriculture and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan.
authors.forename: Haruka
authors.initials: H
authors.lastname: Furuta
authors.affiliation: Department of Animal Sciences, Graduate School of Agriculture and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan; Department of Applied Biological Chemistry, Graduate School of Agriculture and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan.
authors.forename: Fumihiko
authors.initials: F
authors.lastname: Hakuno
authors.affiliation: Molecular Profiling Research Center for Drug Discovery (molprof), National Institute of Advanced Industrial Science and Technology (AIST), 2-4-7 Aomi, Koto-ku, Tokyo, 135-0064, Japan.
authors.forename: Shun-Ichiro
authors.initials: SI
authors.lastname: Iemura
authors.affiliation: Molecular Profiling Research Center for Drug Discovery (molprof), National Institute of Advanced Industrial Science and Technology (AIST), 2-4-7 Aomi, Koto-ku, Tokyo, 135-0064, Japan.
authors.forename: Tohru
authors.initials: T
authors.lastname: Natsume
authors.affiliation: Department of Medical Science, Graduate School of Medicine, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima City, Hiroshima, 734-8553, Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Nakatsu
authors.affiliation: Department of Medical Science, Graduate School of Medicine, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima City, Hiroshima, 734-8553, Japan.
authors.forename: Hideaki
authors.initials: H
authors.lastname: Kamata
authors.affiliation: Department of Medical Science, Graduate School of Medicine, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima City, Hiroshima, 734-8553, Japan.
authors.forename: Tomoichiro
authors.initials: T
authors.lastname: Asano
authors.affiliation: Cell Biology Unit, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama, 226-8501, Japan.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Komada
authors.affiliation: Department of Animal Sciences, Graduate School of Agriculture and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan; Department of Applied Biological Chemistry, Graduate School of Agriculture and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan. Electronic address: atkshin@mail.ecc.u-tokyo.ac.jp.
authors.forename: Shin-Ichiro
authors.initials: SI
authors.lastname: Takahashi
mesh_terms: D056827:Endosomal Sorting Complexes Required for Transport / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D055504:Insulin Receptor Substrate Proteins / Q000378:metabolism*; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D000075702:Nedd4 Ubiquitin Protein Ligases; D015398:Signal Transduction / Q000502:physiology*; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism*; D064570:Ubiquitin-Specific Proteases / Q000378:metabolism*; D057149:Ubiquitinated Proteins / Q000378:metabolism; D054875:Ubiquitination / Q000502:physiology*
chemical_list: D056827:Endosomal Sorting Complexes Required for Transport; C526297:IRS2 protein, human; D055504:Insulin Receptor Substrate Proteins; D057149:Ubiquitinated Proteins; D007334:Insulin-Like Growth Factor I; D000075702:Nedd4 Ubiquitin Protein Ligases; C000618483:Nedd4 protein, human; D044767:Ubiquitin-Protein Ligases; C579226:USP15 protein, human; D064570:Ubiquitin-Specific Proteases
keywords: Insulin receptor substrate (IRS)-2; Insulin-like growth factor (IGF); Nedd4; Ubiquitin-specific protease 15 (USP15); Ubiquitination