OTUB1 enhances TGFβ signalling by inhibiting the ubiquitylation and degradation of active SMAD2/3.
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.
MRC Protein Phosphorylation Unit, College of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5 EH, Scotland, UK.
Lina
L
Herhaus
Mazin
M
Al-Salihi
Thomas
T
Macartney
Simone
S
Weidlich
Gopal P
GP
Sapkota
D000818:Animals; D001897:Boronic Acids / Q000494:pharmacology; D000069286:Bortezomib; D045744:Cell Line, Tumor; D003546:Cysteine Endopeptidases / Q000235:genetics* / Q000378:metabolism; D000072017:Deubiquitinating Enzymes; D005786:Gene Expression Regulation; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D051379:Mice; D010750:Phosphoproteins / Q000235:genetics* / Q000378:metabolism; D010766:Phosphorylation; D061251:Primary Cell Culture; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D061988:Proteasome Inhibitors / Q000494:pharmacology; D055550:Protein Stability; D011719:Pyrazines / Q000494:pharmacology; D015398:Signal Transduction; D051899:Smad2 Protein / Q000235:genetics* / Q000378:metabolism; D051900:Smad3 Protein / Q000235:genetics* / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000235:genetics* / Q000378:metabolism / Q000494:pharmacology; D025801:Ubiquitin / Q000235:genetics / Q000378:metabolism; D054875:Ubiquitination
D001897:Boronic Acids; D010750:Phosphoproteins; D061988:Proteasome Inhibitors; D011719:Pyrazines; C497782:SMAD2 protein, human; C497790:SMAD3 protein, human; D051899:Smad2 Protein; D051900:Smad3 Protein; D016212:Transforming Growth Factor beta; D025801:Ubiquitin; D049452:Green Fluorescent Proteins; D000069286:Bortezomib; D000072017:Deubiquitinating Enzymes; C538826:OTUB1 protein, human; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex