The hypoxia-controlled FBXL14 ubiquitin ligase targets SNAIL1 for proteasome degradation.
The transcription factor SNAIL1 is a master regulator of epithelial to mesenchymal transition. SNAIL1 is a very unstable protein, and its levels are regulated by the E3 ubiquitin ligase beta-TrCP1 that interacts with SNAIL1 upon its phosphorylation by GSK-3beta. Here we show that SNAIL1 polyubiquitylation and degradation may occur in conditions precluding SNAIL1 phosphorylation by GSK-3beta, suggesting that additional E3 ligases participate in the control of SNAIL1 protein stability. In particular, we demonstrate that the F-box E3 ubiquitin ligase FBXl14 interacts with SNAIL1 and promotes its ubiquitylation and proteasome degradation independently of phosphorylation by GSK-3beta. In vivo, inhibition of FBXl14 using short hairpin RNA stabilizes both ectopically expressed and endogenous SNAIL1. Moreover, the expression of FBXl14 is potently down-regulated during hypoxia, a condition that increases the levels of SNAIL1 protein but not SNAIL1 mRNA. FBXL14 mRNA is decreased in tumors with a high expression of two proteins up-regulated in hypoxia, carbonic anhydrase 9 and TWIST1. In addition, Twist1 small interfering RNA prevents hypoxia-induced Fbxl14 down-regulation and SNAIL1 stabilization in NMuMG cells. Altogether, these results demonstrate the existence of an alternative mechanism controlling SNAIL1 protein levels relevant for the induction of SNAIL1 during hypoxia.
Viñas-Castells
Rosa
R
From the Programa de Recerca en Càncer, Institut Municipal d'Investigació Mèdica, Hospital del Mar, Parc de Recerca Biomèdica de Barcelona, Doctor Aiguader 88, E-08003 Barcelona, Spain.
Beltran
Manuel
M
From the Programa de Recerca en Càncer, Institut Municipal d'Investigació Mèdica, Hospital del Mar, Parc de Recerca Biomèdica de Barcelona, Doctor Aiguader 88, E-08003 Barcelona, Spain.
Valls
Gabriela
G
From the Programa de Recerca en Càncer, Institut Municipal d'Investigació Mèdica, Hospital del Mar, Parc de Recerca Biomèdica de Barcelona, Doctor Aiguader 88, E-08003 Barcelona, Spain.
Gómez
Irene
I
the Servicio de Oncologia Médica, Hospital Universitario Puerta de Hierro, E-28222 Majadahonda, Spain, and.
García
José Miguel
JM
the Servicio de Oncologia Médica, Hospital Universitario Puerta de Hierro, E-28222 Majadahonda, Spain, and.
Montserrat-Sentís
Bàrbara
B
From the Programa de Recerca en Càncer, Institut Municipal d'Investigació Mèdica, Hospital del Mar, Parc de Recerca Biomèdica de Barcelona, Doctor Aiguader 88, E-08003 Barcelona, Spain.
Baulida
Josep
J
From the Programa de Recerca en Càncer, Institut Municipal d'Investigació Mèdica, Hospital del Mar, Parc de Recerca Biomèdica de Barcelona, Doctor Aiguader 88, E-08003 Barcelona, Spain.
Bonilla
Félix
F
the Servicio de Oncologia Médica, Hospital Universitario Puerta de Hierro, E-28222 Majadahonda, Spain, and.
de Herreros
Antonio García
AG
From the Programa de Recerca en Càncer, Institut Municipal d'Investigació Mèdica, Hospital del Mar, Parc de Recerca Biomèdica de Barcelona, Doctor Aiguader 88, E-08003 Barcelona, Spain; the Departament de Ciències Experimentals i de la Salut, Universitat Pompeu Fabra, E-08003 Barcelona, Spain. Electronic address: agarcia@imim.es.
Díaz
Víctor M
VM
From the Programa de Recerca en Càncer, Institut Municipal d'Investigació Mèdica, Hospital del Mar, Parc de Recerca Biomèdica de Barcelona, Doctor Aiguader 88, E-08003 Barcelona, Spain; the Departament de Ciències Experimentals i de la Salut, Universitat Pompeu Fabra, E-08003 Barcelona, Spain. Electronic address: vdiaz@imim.es.
D000818:Animals; D001665:Binding Sites; D015153:Blotting, Western; D015687:Cell Hypoxia; D002460:Cell Line; D045744:Cell Line, Tumor; D015536:Down-Regulation; D044783:F-Box Proteins / Q000235:genetics / Q000378:metabolism*; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism; D000071679:Glycogen Synthase Kinase 3 beta; D047468:Immunoprecipitation; D051379:Mice; D009154:Mutation; D041681:NIH 3T3 Cells; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism*; D011485:Protein Binding; D034622:RNA Interference; D000071250:Snail Family Transcription Factors; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014162:Transfection; D051879:Twist-Related Protein 1 / Q000235:genetics / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism*; D054875:Ubiquitination
D044783:F-Box Proteins; C547521:FBXL14 protein, human; D009687:Nuclear Proteins; C000604407:SNAI1 protein, human; C000604429:Snai1 protein, mouse; D000071250:Snail Family Transcription Factors; C103173:TWIST1 protein, human; D014157:Transcription Factors; D051879:Twist-Related Protein 1; C067250:Twist1 protein, mouse; D044767:Ubiquitin-Protein Ligases; C000605506:GSK3B protein, human; D000071679:Glycogen Synthase Kinase 3 beta; C000605507:Gsk3b protein, mouse; D038362:Glycogen Synthase Kinase 3; D046988:Proteasome Endopeptidase Complex