Vaccinia-Related Kinase 2 Controls the Stability of the Eukaryotic Chaperonin TRiC/CCT by Inhibiting the Deubiquitinating Enzyme USP25.

Molecular chaperones monitor the proper folding of misfolded proteins and function as the first line of defense against mutant protein aggregation in neurodegenerative diseases. The eukaryotic chaperonin TRiC is a potent suppressor of mutant protein aggregation and toxicity in early stages of disease progression. Elucidation of TRiC functional regulation will enable us to better understand the pathological mechanisms of neurodegeneration. We have previously shown that vaccinia-related kinase 2 (VRK2) downregulates TRiC protein levels through the ubiquitin-proteasome system by recruiting the E3 ligase COP1. However, although VRK2 activity was necessary in TRiC downregulation, the phosphorylated substrate was not determined. Here, we report that USP25 is a novel TRiC interacting protein that is also phosphorylated by VRK2. USP25 catalyzed deubiquitination of the TRiC protein and stabilized the chaperonin, thereby reducing accumulation of misfolded polyglutamine protein aggregates. Notably, USP25 deubiquitinating activity was suppressed when VRK2 phosphorylated the Thr(680), Thr(727), and Ser(745) residues. Impaired USP25 deubiquitinating activity after VRK2-mediated phosphorylation may be a critical pathway in TRiC protein destabilization.
AuthorsSangjune Kim, Dohyun Lee, Juhyun Lee, Haengjin Song, Hyo-Jin Kim, Kyong-Tai Kim
JournalMolecular and cellular biology (Mol Cell Biol) Vol. 35 Issue 10 Pg. 1754-62 (May 2015) ISSN: 1098-5549 [Electronic] United States
PMID25755282 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
CopyrightCopyright © 2015, American Society for Microbiology. All Rights Reserved.
Chemical References
  • Peptides
  • polyglutamine
  • Protein-Serine-Threonine Kinases
  • VRK2 protein, human
  • USP25 protein, human
  • Ubiquitin Thiolesterase
  • Chaperonin Containing TCP-1
  • Cell Line
  • Chaperonin Containing TCP-1 (metabolism)
  • Gene Expression Regulation
  • HEK293 Cells
  • Humans
  • Peptides (metabolism)
  • Phosphorylation
  • Protein-Serine-Threonine Kinases (metabolism)
  • Substrate Specificity
  • Ubiquitin Thiolesterase (genetics, metabolism)
  • Ubiquitination

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