Ubiquitin-dependent degradation of Id1 and Id3 is mediated by the COP9 signalosome

Matthias Berse, Mangkey Bounpheng, Xiaohua Huang, Barbara Christy, Christian Pollmann, Wolfgang Dubiel

Research output: Contribution to journalArticlepeer-review

43 Scopus citations


Recently, evidence is accumulating pointing to a function of the COP9 signalosome (CSN) in regulation of ubiquitination by specific ubiquitin ligases. Here, we demonstrate by mammalian two-hybrid analysis that the transcriptional regulators and substrates of the ubiquitin system Id1 and Id3, but not Id2 and Id4, bind to the CSN subunit CSN5. Pull-down experiments revealed that Id3 physically interacts with the CSN complex. Additional far Western and pull-down studies with Id3 support our two-hybrid data and show that the transcription regulator can bind to CSN5 and CSN7. Recombinant Id3 is not phosphorylated by the CSN-associated kinases CK2 and PKD. However, it inhibits c-Jun and CSN2 phosphorylation by the isolated CSN complex and by the recombinant CK2. The inhibitors of CSN associated kinases, curcumin and emodin, significantly induce ubiquitination and proteasome-dependent degradation of transiently expressed Id3 in HeLa cells. Proteasome-dependent degradation of endogenous Id1 in HeLa cells is also stimulated by treatment with curcumin or emodin. Ubiquitination of Id3 is shown directly by cotransfection of HeLa cells with Id3 and His-ubiquitin cDNA. Curcumin increased Id3-ubiquitin conjugate formation, as shown by Western blotting and His-pull-downs. In addition, overexpression of CSN2 leads to stabilization of Id3 protein. On the basis of these data, it is speculated that CSN-mediated phosphorylation inhibits ubiquitination of Id1 and Id3.

Original languageEnglish (US)
Pages (from-to)361-370
Number of pages10
JournalJournal of Molecular Biology
Issue number2
StatePublished - Oct 15 2004


  • COP9 signalosome
  • Id1
  • Id3
  • proteasome
  • ubiquitin ligase

ASJC Scopus subject areas

  • Structural Biology
  • Molecular Biology


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