<p>The E3 ligase substrate adapter cereblon (CRBN), the primary target of clinical agents thalidomide and lenalidomide, recognizes endogenous substrates bearing the C-terminal cyclic imide modification. Although C-terminal cyclic imides can form spontaneously, an enzyme that regulates their formation and thereby promotes a biological pathway connecting substrates to CRBN is unknown. Here we report that protein carboxymethyltransferase (PCMT1) promotes formation of C-terminal cyclic imides on C-terminal asparagine residues of CRBN substrates. PCMT1 and CRBN coregulate the levels of metabolic enzymes including glutamine synthetase and inorganic pyrophosphatase 1 in vitro, in cells and in vivo, and this regulation is associated with the proepileptic phenotype of CRBN knockout mouse models. The discovery of an enzyme that regulates CRBN substrates through the C-terminal cyclic imide reveals a previously unknown biological pathway that is perturbed by thalidomide derivatives and provides a biochemical basis for the connection between multiple biological processes and CRBN.</p><p></p>

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PCMT1 generates the C-terminal cyclic imide degron on CRBN substrates

  • Zhenguang Zhao,
  • Wenqing Xu,
  • Ethan Yang Feng,
  • Shiyun Cao,
  • Alba Hermoso-López,
  • Pablo Peña-Vega,
  • Hannah C. Lloyd,
  • Abigail K. D. Porter,
  • Manuel Guzmán,
  • Ning Zheng,
  • Christina M. Woo

摘要

The E3 ligase substrate adapter cereblon (CRBN), the primary target of clinical agents thalidomide and lenalidomide, recognizes endogenous substrates bearing the C-terminal cyclic imide modification. Although C-terminal cyclic imides can form spontaneously, an enzyme that regulates their formation and thereby promotes a biological pathway connecting substrates to CRBN is unknown. Here we report that protein carboxymethyltransferase (PCMT1) promotes formation of C-terminal cyclic imides on C-terminal asparagine residues of CRBN substrates. PCMT1 and CRBN coregulate the levels of metabolic enzymes including glutamine synthetase and inorganic pyrophosphatase 1 in vitro, in cells and in vivo, and this regulation is associated with the proepileptic phenotype of CRBN knockout mouse models. The discovery of an enzyme that regulates CRBN substrates through the C-terminal cyclic imide reveals a previously unknown biological pathway that is perturbed by thalidomide derivatives and provides a biochemical basis for the connection between multiple biological processes and CRBN.