Abstract
R-spondin proteins strongly potentiate Wnt signalling and function as stem-cell growth factors. Despite the biological and therapeutic significance, the molecular mechanism of R-spondin action remains unclear. Here we show that the cell-surface transmembrane E3 ubiquitin ligase zinc and ring finger 3 (ZNRF3) and its homologue ring finger 43 (RNF43) are negative feedback regulators of Wnt signalling. ZNRF3 is associated with the Wnt receptor complex, and inhibits Wnt signalling by promoting the turnover of frizzled and LRP6. Inhibition of ZNRF3 enhances Wnt/β-catenin signalling and disrupts Wnt/planar cell polarity signalling in vivo. Notably, R-spondin mimics ZNRF3 inhibition by increasing the membrane level of Wnt receptors. Mechanistically, R-spondin interacts with the extracellular domain of ZNRF3 and induces the association between ZNRF3 and LGR4, which results in membrane clearance of ZNRF3. These data suggest that R-spondin enhances Wnt signalling by inhibiting ZNRF3. Our study provides new mechanistic insights into the regulation of Wnt receptor turnover, and reveals ZNRF3 as a tractable target for therapeutic exploration.
Links
Authors
Hao HX, Xie Y, Zhang Y, Charlat O, Oster E, Avello M, Lei H, Mickanin C, Liu D, Ruffner H, Mao X, Ma Q, Zamponi R, Bouwmeester T, Finan PM, Kirschner MW, Porter JA, Serluca FC, Cong F
Institution
Novartis Institutes for Biomedical Research, 250 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA.
Source
Nature 485:7397 2012 May 10 pg 195-200MeSH
AnimalsCell Polarity
Colorectal Neoplasms
DNA-Binding Proteins
Feedback, Physiological
Female
Frizzled Receptors
HEK293 Cells
Humans
Low Density Lipoprotein Receptor-Related Protein-6
Male
Mice
Mice, Knockout
Oncogene Proteins
Protein Stability
Protein Structure, Tertiary
Receptors, G-Protein-Coupled
Receptors, Wnt
Thrombospondins
Ubiquitin-Protein Ligases
Ubiquitination
Wnt Signaling Pathway
Xenopus
Zebrafish
beta Catenin
Pub Type(s)
Journal ArticleLanguage
eng
PubMed ID
22575959
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