The TRC8 Ubiquitin Ligase Is Sterol Regulated and Interacts with Lipid and Protein Biosynthetic Pathways

  • Jason P. Lee
    Authors' Affiliations: 1Division of Hematology/Oncology, Department of Medicine and Hollings Cancer Center, Medical University of South Carolina, Charleston, South Carolina and Departments of 2Medical Oncology, 3Physiology and Biophysics, and 4Cell and Developmental Biology, University of Colorado at Denver and Health Science Center, Aurora, Colorado
  • Anne Brauweiler
    Authors' Affiliations: 1Division of Hematology/Oncology, Department of Medicine and Hollings Cancer Center, Medical University of South Carolina, Charleston, South Carolina and Departments of 2Medical Oncology, 3Physiology and Biophysics, and 4Cell and Developmental Biology, University of Colorado at Denver and Health Science Center, Aurora, Colorado
  • Michael Rudolph
    Authors' Affiliations: 1Division of Hematology/Oncology, Department of Medicine and Hollings Cancer Center, Medical University of South Carolina, Charleston, South Carolina and Departments of 2Medical Oncology, 3Physiology and Biophysics, and 4Cell and Developmental Biology, University of Colorado at Denver and Health Science Center, Aurora, Colorado
  • Joan E. Hooper
    Authors' Affiliations: 1Division of Hematology/Oncology, Department of Medicine and Hollings Cancer Center, Medical University of South Carolina, Charleston, South Carolina and Departments of 2Medical Oncology, 3Physiology and Biophysics, and 4Cell and Developmental Biology, University of Colorado at Denver and Health Science Center, Aurora, Colorado
  • Harry A. Drabkin
    Authors' Affiliations: 1Division of Hematology/Oncology, Department of Medicine and Hollings Cancer Center, Medical University of South Carolina, Charleston, South Carolina and Departments of 2Medical Oncology, 3Physiology and Biophysics, and 4Cell and Developmental Biology, University of Colorado at Denver and Health Science Center, Aurora, Colorado
  • Robert M. Gemmill
    Authors' Affiliations: 1Division of Hematology/Oncology, Department of Medicine and Hollings Cancer Center, Medical University of South Carolina, Charleston, South Carolina and Departments of 2Medical Oncology, 3Physiology and Biophysics, and 4Cell and Developmental Biology, University of Colorado at Denver and Health Science Center, Aurora, Colorado

書誌事項

公開日
2010-01-17
DOI
  • 10.1158/1541-7786.mcr-08-0491
公開者
American Association for Cancer Research (AACR)

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<jats:title>Abstract</jats:title> <jats:p>TRC8/RNF139 encodes an endoplasmic reticulum–resident E3 ubiquitin ligase that inhibits growth in a RING- and ubiquitylation-dependent manner. TRC8 also contains a predicted sterol-sensing domain. Here, we report that TRC8 protein levels are sterol responsive and that it binds and stimulates ubiquitylation of the endoplasmic reticulum anchor protein INSIG. Induction of TRC8 destabilized the precursor forms of the transcription factors SREBP-1 and SREBP-2. Loss of SREBP precursors was proteasome dependent, required a functional RING domain, occurred without generating processed nuclear forms, and suppressed SREBP target genes. TRC8 knockdown had opposite effects in sterol-deprived cells. In Drosophila, growth inhibition by DTrc8 was genetically suppressed by loss of specific Mprlp, Padlp N-terminal domain–containing proteins found in the COP9 signalosome and eIF3. DTrc8 genetically and physically interacted with two eIF3 subunits: eIF3f and eIF3h. Coimmunoprecipitation experiments confirmed these interactions in mammalian cells, and TRC8 overexpression suppressed polysome profiles. Moreover, high–molecular weight ubiquitylated proteins were observed in eIF3 immunoprecipitations from TRC8-overexpressing cells. Thus, TRC8 function may provide a regulatory link between the lipid and protein biosynthetic pathways. Mol Cancer Res; 8(1); 93–106</jats:p>

収録刊行物

  • Molecular Cancer Research

    Molecular Cancer Research 8 (1), 93-106, 2010-01-17

    American Association for Cancer Research (AACR)

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