title: WNT-3A regulates an Axin1/NRF2 complex that regulates antioxidant metabolism in hepatocytes.
abstract: OBJECTIVE
  Nuclear factor (erythroid-derived 2)-like 2 (NRF2) is a master regulator of oxidant and xenobiotic metabolism, but it is unknown how it is regulated to provide basal expression of this defense system. Here, we studied the putative connection between NRF2 and the canonical WNT pathway, which modulates hepatocyte metabolism.
  
  
  RESULTS
  WNT-3A increased the levels of NRF2 and its transcriptional signature in mouse hepatocytes and HEK293T cells. The use of short interfering RNAs in hepatocytes and mouse embryonic fibroblasts which are deficient in the redox sensor Kelch-like ECH-associated protein 1 (KEAP1) indicated that WNT-3A activates NRF2 in a β-Catenin- and KEAP1-independent manner. WNT-3A stabilized NRF2 by preventing its GSK-3-dependent phosphorylation and subsequent SCF/β-TrCP-dependent ubiquitination and proteasomal degradation. Axin1 and NRF2 were physically associated in a protein complex that was regulated by WNT-3A, involving the central region of Axin1 and the Neh4/Neh5 domains of NRF2. Axin1 knockdown increased NRF2 protein levels, while Axin1 stabilization with Tankyrase inhibitors blocked WNT/NRF2 signaling. The relevance of this novel pathway was assessed in mice with a conditional deletion of Axin1 in the liver, which showed upregulation of the NRF2 signature in hepatocytes and disruption of liver zonation of antioxidant metabolism.
  
  
  METHODS
  NRF2 takes part in a protein complex with Axin1 that is regulated by the canonical WNT pathway. This new WNT-NRF2 axis controls the antioxidant metabolism of hepatocytes.
  
  
  CONCLUSIONS
  These results uncover the participation of NRF2 in a WNT-regulated signalosome that participates in basal maintenance of hepatic antioxidant metabolism.
authors.affiliation: 1 Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), ISCIII , Madrid, Spain .
authors.forename: Patricia
authors.initials: P
authors.lastname: Rada
authors.forename: Ana I
authors.initials: AI
authors.lastname: Rojo
authors.forename: Anika
authors.initials: A
authors.lastname: Offergeld
authors.forename: Gui Jie
authors.initials: GJ
authors.lastname: Feng
authors.forename: Juan P
authors.initials: JP
authors.lastname: Velasco-Martín
authors.forename: José Manuel
authors.initials: JM
authors.lastname: González-Sancho
authors.forename: Ángela M
authors.initials: ÁM
authors.lastname: Valverde
authors.forename: Trevor
authors.initials: T
authors.lastname: Dale
authors.forename: Javier
authors.initials: J
authors.lastname: Regadera
authors.forename: Antonio
authors.initials: A
authors.lastname: Cuadrado
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000378:metabolism*; D060466:Axin Protein / Q000235:genetics* / Q000378:metabolism*; D002460:Cell Line; D055785:Gene Knockdown Techniques; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism; D000071679:Glycogen Synthase Kinase 3 beta; D022781:Hepatocytes / Q000378:metabolism*; D006801:Humans; D008099:Liver / Q000166:cytology / Q000378:metabolism; D051379:Mice; D008822:Mice, Transgenic; D060509:Wnt3A Protein / Q000378:metabolism*
chemical_list: C555451:AXIN1 protein, human; D000975:Antioxidants; D060466:Axin Protein; C555452:Axin1 protein, mouse; D060509:Wnt3A Protein; D000071679:Glycogen Synthase Kinase 3 beta; D038362:Glycogen Synthase Kinase 3