OTUB1 enhances TGFβ signalling by inhibiting the ubiquitylation and degradation of active SMAD2/3

Nat Commun. 2013;4:2519. doi: 10.1038/ncomms3519.

Abstract

SMAD transcription factors are key intracellular transducers of TGFβ cytokines. SMADs are tightly regulated to ensure balanced cellular responses to TGFβ signals. Ubiquitylation has a key role in regulating SMAD stability and activity. Several E3 ubiquitin ligases that regulate the turnover of SMADs are known; however, proteins that prevent the ubiquitylation or cause deubiquitylation of active SMADs remain undefined. Here we demonstrate that OTUB1 is recruited to the active phospho-SMAD2/3 complex only on TGFβ induction. Further, OTUB1 has a crucial role in TGFβ-mediated gene transcription and cellular migration. OTUB1 inhibits the ubiquitylation of phospho-SMAD2/3 by binding to and inhibiting the E2 ubiquitin-conjugating enzymes independent of its catalytic activity. Consequently, depletion of OTUB1 in cells causes a rapid loss in levels of TGFβ-induced phospho-SMAD2/3, which is rescued by the proteasomal inhibitor bortezomib. Our findings uncover a signal-induced phosphorylation-dependent recruitment of OTUB1 to its target in the TGFβ pathway.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Boronic Acids / pharmacology
  • Bortezomib
  • Cell Line, Tumor
  • Cysteine Endopeptidases / genetics*
  • Cysteine Endopeptidases / metabolism
  • Gene Expression Regulation
  • Genes, Reporter
  • Green Fluorescent Proteins / genetics
  • Green Fluorescent Proteins / metabolism
  • Humans
  • Mice
  • Phosphoproteins / genetics*
  • Phosphoproteins / metabolism
  • Phosphorylation
  • Primary Cell Culture
  • Proteasome Endopeptidase Complex / metabolism
  • Proteasome Inhibitors / pharmacology
  • Protein Stability
  • Pyrazines / pharmacology
  • Signal Transduction
  • Smad2 Protein / genetics*
  • Smad2 Protein / metabolism
  • Smad3 Protein / genetics*
  • Smad3 Protein / metabolism
  • Transforming Growth Factor beta / genetics*
  • Transforming Growth Factor beta / metabolism
  • Transforming Growth Factor beta / pharmacology
  • Ubiquitin / genetics
  • Ubiquitin / metabolism
  • Ubiquitination

Substances

  • Boronic Acids
  • Phosphoproteins
  • Proteasome Inhibitors
  • Pyrazines
  • SMAD2 protein, human
  • SMAD3 protein, human
  • Smad2 Protein
  • Smad3 Protein
  • Transforming Growth Factor beta
  • Ubiquitin
  • Green Fluorescent Proteins
  • Bortezomib
  • Cysteine Endopeptidases
  • otubain 1 protein, human
  • Proteasome Endopeptidase Complex