Glutamine Triggers Acetylation-Dependent Degradation of Glutamine Synthetase via the Thalidomide Receptor Cereblon

Mol Cell. 2016 Mar 17;61(6):809-20. doi: 10.1016/j.molcel.2016.02.032.

Abstract

Cereblon (CRBN), a substrate receptor for the cullin-RING ubiquitin ligase 4 (CRL4) complex, is a direct protein target for thalidomide teratogenicity and antitumor activity of immunomodulatory drugs (IMiDs). Here we report that glutamine synthetase (GS) is an endogenous substrate of CRL4(CRBN). Upon exposing cells to high glutamine concentration, GS is acetylated at lysines 11 and 14, yielding a degron that is necessary and sufficient for binding and ubiquitylation by CRL4(CRBN) and degradation by the proteasome. Binding of acetylated degron peptides to CRBN depends on an intact thalidomide-binding pocket but is not competitive with IMiDs. These findings reveal a feedback loop involving CRL4(CRBN) that adjusts GS protein levels in response to glutamine and uncover a new function for lysine acetylation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acetylation
  • Adaptor Proteins, Signal Transducing
  • Glutamate-Ammonia Ligase / metabolism*
  • Glutamine / metabolism
  • HEK293 Cells
  • Humans
  • Immunologic Factors / metabolism*
  • Lysine / metabolism
  • Peptide Hydrolases / metabolism*
  • Proteasome Endopeptidase Complex / metabolism
  • Proteolysis
  • Thalidomide / metabolism
  • Ubiquitin-Protein Ligases / metabolism*
  • Ubiquitination

Substances

  • Adaptor Proteins, Signal Transducing
  • CRBN protein, human
  • IL17RB protein, human
  • Immunologic Factors
  • Glutamine
  • Thalidomide
  • Ubiquitin-Protein Ligases
  • Peptide Hydrolases
  • Proteasome Endopeptidase Complex
  • Glutamate-Ammonia Ligase
  • Lysine