Ubiquitin Ligase RNF146 Regulates Tankyrase and Axin to Promote Wnt Signaling

University of Birmingham, United Kingdom
PLoS ONE (Impact Factor: 3.53). 07/2011; 6(7):e22595. DOI: 10.1371/journal.pone.0022595
Source: PubMed

ABSTRACT Canonical Wnt signaling is controlled intracellularly by the level of β-catenin protein, which is dependent on Axin scaffolding of a complex that phosphorylates β-catenin to target it for ubiquitylation and proteasomal degradation. This function of Axin is counteracted through relocalization of Axin protein to the Wnt receptor complex to allow for ligand-activated Wnt signaling. AXIN1 and AXIN2 protein levels are regulated by tankyrase-mediated poly(ADP-ribosyl)ation (PARsylation), which destabilizes Axin and promotes signaling. Mechanistically, how tankyrase limits Axin protein accumulation, and how tankyrase levels and activity are regulated for this function, are currently under investigation. By RNAi screening, we identified the RNF146 RING-type ubiquitin E3 ligase as a positive regulator of Wnt signaling that operates with tankyrase to maintain low steady-state levels of Axin proteins. RNF146 also destabilizes tankyrases TNKS1 and TNKS2 proteins and, in a reciprocal relationship, tankyrase activity reduces RNF146 protein levels. We show that RNF146, tankyrase, and Axin form a protein complex, and that RNF146 mediates ubiquitylation of all three proteins to target them for proteasomal degradation. RNF146 is a cytoplasmic protein that also prevents tankyrase protein aggregation at a centrosomal location. Tankyrase auto-PARsylation and PARsylation of Axin is known to lead to proteasome-mediated degradation of these proteins, and we demonstrate that, through ubiquitylation, RNF146 mediates this process to regulate Wnt signaling.

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Available from: Wendy Sandoval, Aug 15, 2015
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    • "Given that structural and biochemical analyses revealed that the binding specificity of these domains are dependent on the neighboring amino acids surrounding the modified sites [62] [68], these macrodomains will likely enrich for a restricted set of native ADP-ribosylated partners within cells. Besides macrodomains, the WWE domain from RNF146 has also been shown to be responsible for binding PARylated PARP1 and PARP5a [69] [70] [71]. Given that the WWE domain specifically recognizes the smallest structural subunit for PAR, iso-ADP-ribose [72] (c.f. "
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    ABSTRACT: ADP-ribosylation refers to the addition of one or more ADP-ribose units onto protein substrates and this protein modification has been implicated in various cellular processes including DNA damage repair, RNA metabolism, transcription and cell cycle regulation. This review focuses on a compilation of large-scale proteomics studies that identify ADP-ribosylated proteins and their associated proteins by mass spectrometry using a variety of enrichment strategies. Some methods, such as the use of a poly(ADP-ribose)-specific antibody and boronate affinity chromatography and NAD+ analogues, have been employed for decades while others, such as the use of protein microarrays and recombinant proteins that bind ADP-ribose moieties (such as macrodomains), have only recently been developed. The advantages and disadvantages of each method and whether these methods are specific for identifying mono(ADP-ribosyl)ated and poly(ADP-ribosyl)ated proteins will be discussed. Lastly, since poly(ADP-ribose) is heterogeneous in length, it has been difficult to attain a mass signature associated with the modification sites. Several strategies on how to reduce polymer chain length heterogeneity for site identification will be reviewed.This article is protected by copyright. All rights reserved
    Proteomics 09/2014; 15(2-3). DOI:10.1002/pmic.201400217 · 3.97 Impact Factor
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    • "Previously , Stegmeier lab revealed that Axin stability is regulated by Tankyrase and Tankyrase-mediated poly-ADP-ribose modification (PARsylation) of Axin is linked to Axin polyubiquitylation and subsequent degradation by the proteasome (Huang et al., 2009). Later, RNF146 was uncovered to be the E3 ligase for mediating Tankyrase-dependent degradation of Axin, thus playing a positive role in Wnt signaling (Callow et al., 2011; Zhang et al., 2011). Ubiquitin-specific protease 34 (USP34) is also reported to associate with Axin and control its levels, whereby modulating Wnt signaling (Lui et al., 2011). "
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    ABSTRACT: The Wnt signaling pathway plays crucial roles during embryonic development, whose aberration is implicated in a variety of human cancers. Axin, a key component of canonical Wnt pathway, plays dual roles in modulating Wnt signaling: on one hand, Axin scaffolds the "β-catenin destruction complex" to promote β-catenin degradation and therefore inhibits the Wnt signal transduction; on the other hand, Axin interacts with LRP5/6 and facilitates the recruitment of GSK3 to the plasma membrane to promote LRP5/6 phosphorylation and Wnt signaling. The differential assemblies of Axin with these two distinct complexes have to be tightly controlled for appropriate transduction of the "on" or "off" Wnt signal. So far, there are multiple mechanisms revealed in the regulation of Axin activity, such as post-transcriptional modulation, homo/hetero-polymerization and auto-inhibition. These mechanisms may work cooperatively to modulate the function of Axin, thereby playing an important role in controlling the canonical Wnt signaling. In this review, we will focus on the recent progresses regarding the regulation of Axin function in canonical Wnt signaling.
    Protein & Cell 01/2014; 5(3). DOI:10.1007/s13238-014-0019-2 · 2.85 Impact Factor
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    • "4. Ubiquitin ligase RNF146 (RING finger protein 146) RNF146 is a RING-domain E3 ubiquitin ligase. RNF146 can act as a positive regulator of Wnt signaling through ubiquitylating and destabilizing Axin and tankyrase (Callow et al, 2011). 5. C/EBPβ, Shikonin and Testosterone CCAAT/enhancer binding protein β (C/EBPβ) is rapidly induced in early stages of adipogenesis and is responsible for transcriptional induction of Peroxisome proliferatoractivated receptor γ (PPARγ) and C/EBPα by maintaining active Wnt/β-catenin signaling, after addition of adipogenic inducers. "
    Embryogenesis, 04/2012; , ISBN: 978-953-51-0466-7
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