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 β-TrCP1 that interacts with SNAIL1 upon its phosphorylation by GSK-3β. Here we show that SNAIL1 polyubiquitylation and degradation may occur in conditions precluding SNAIL1 phosphorylation by GSK-3β, 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-3β. 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.
The Hypoxia-controlled {FBXL}14 Ubiquitin Ligase Targets {SNAIL}1 for Proteasome Degradation / Vi(\~(n))as-Castells, Rosa; Beltran, Manuel; Valls, Gabriela; G('(o))mez, Irene; Jos('(e)) Miguel Garc('(\i))a, ; Montserrat-Sent('(\i))s, B(\`(a))rbara; Baulida, Josep; Bonilla, F('(e))lix; Antonio Garc('(\i))a de Herreros, ; D('(\i))az, V('(\i))ctor M.. - In: THE JOURNAL OF BIOLOGICAL CHEMISTRY. - ISSN 0021-9258. - 285:6(2010), pp. 3794-3805. [10.1074/jbc.m109.065995]
The Hypoxia-controlled {FBXL}14 Ubiquitin Ligase Targets {SNAIL}1 for Proteasome Degradation
Manuel Beltran;
2010
Abstract
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 β-TrCP1 that interacts with SNAIL1 upon its phosphorylation by GSK-3β. Here we show that SNAIL1 polyubiquitylation and degradation may occur in conditions precluding SNAIL1 phosphorylation by GSK-3β, 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-3β. 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.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
