Stabilization of the E3 ubiquitin ligase Nrdp1 by the deubiquitinating enzyme USP8

Xiuli Wu, Lily Yen, Lisa Irwin, Colleen A Sweeney, Kermit L Carraway

Research output: Contribution to journalArticle

113 Scopus citations

Abstract

Nrdp1 is a RING finger-containing E3 ubiquitin ligase that physically interacts with and regulates steady-state cellular levels of the ErbB3 and ErbB4 receptor tyrosine kinases and has been implicated in the degradation of the inhibitor-of-apoptosis protein BRUCE. Here we demonstrate that the Nrdp1 protein undergoes efficient proteasome-dependent degradation and that mutations in its RING finger domain that disrupt ubiquitin ligase activity enhance stability. These observations suggest that Nrdp1 self-ubiquitination and stability could play an important role in regulating the activity of this protein. Using affinity chromatography, we identified the deubiquitinating enzyme USP8 (also called Ubpy) as a protein that physically interacts with Nrdp1. Nrdp1 and USP8 could be coimmunoprecipitated, and in transfected cells USP8 specifically bound to Nrdp1 but not cbl, a RING finger E3 ligase involved in ligand-stimulated epidermal growth factor receptor down-regulation. The USP8 rhodanese and catalytic domains mediated Nrdp1 binding. USP8 markedly enhanced the stability of Nrdp1, and a point mutant that disrupts USP8 catalytic activity destabilized endogenous Nrdp1. Our results indicate that Nrdp1 is a specific target for the USP8 deubiquitinating enzyme and are consistent with a model where USP8 augments Nrdp1 activity by mediating its stabilization.

Original languageEnglish (US)
Pages (from-to)7748-7757
Number of pages10
JournalMolecular and Cellular Biology
Volume24
Issue number17
DOIs
StatePublished - Sep 2004

ASJC Scopus subject areas

  • Molecular Biology
  • Genetics
  • Cell Biology

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