APC mutations disrupt ß-catenin destruction complex condensates organized by Axin phase separation.

The Wnt/ß-catenin pathway is critical to maintaining cell fate decisions. Recent study showed that liquid-liquid-phase separation (LLPS) of Axin organized the ß-catenin destruction complex condensates in a normal cellular state. Mutations inactivating the APC gene are found in approximately 80% of all human colorectal cancer (CRC). However, the molecular mechanism of the formation of ß-catenin destruction complex condensates organized by Axin phase separation and how APC mutations impact the condensates are still unclear. Here, we report that the ß-catenin destruction complex, which is constructed by Axin, was assembled condensates via a phase separation process in CRC cells. The key role of wild-type APC is to stabilize destruction complex condensates. Surprisingly, truncated APC did not affect the formation of condensates, and GSK 3ß and CK1α were unsuccessfully recruited, preventing ß-catenin phosphorylation and resulting in accumulation in the cytoplasm of CRCs. Besides, we propose that the phase separation ability of Axin participates in the nucleus translocation of ß-catenin and be incorporated and concentrated into transcriptional condensates, affecting the transcriptional activity of Wnt signaling pathway.

Feedback in the ß-catenin destruction complex imparts bistability and cellular memory.

Wnt ligands are considered classical morphogens, for which the strength of the cellular response is proportional to the concentration of the ligand. Herein, we show an emergent property of bistability arising from feedback among the Wnt destruction complex proteins that target the key transcriptional co-activator ß-catenin for degradation. Using biochemical reconstitution, we identified positive feedback between the scaffold protein Axin and the kinase glycogen synthase kinase 3 (GSK3). Theoretical modeling of this feedback between Axin and GSK3 suggested that the activity of the destruction complex exhibits bistable behavior. We experimentally confirmed these predictions by demonstrating that cellular cytoplasmic ß-catenin concentrations exhibit an "all-or-none" response with sustained memory (hysteresis) of the signaling input. This bistable behavior was transformed into a graded response and memory was lost through inhibition of GSK3. These findings provide a mechanism for establishing decisive, switch-like cellular response and memory upon Wnt pathway stimulation.

Dishevelled phase separation promotes Wnt signalosome assembly and destruction complex disassembly.

The amplitude of Wnt/ß-catenin signaling is precisely controlled by the assembly of the cell surface-localized Wnt receptor signalosome and the cytosolic ß-catenin destruction complex. How these two distinct complexes are coordinately controlled remains largely unknown. Here, we demonstrated that the signalosome scaffold protein Dishevelled 2 (Dvl2) undergoes liquid-liquid phase separation (LLPS). Dvl2 LLPS is mediated by an intrinsically disordered region and facilitated by components of the signalosome, such as the receptor Fzd5. Assembly of the signalosome is initiated by rapid recruitment of Dvl2 to the membrane, followed by slow and dynamic recruitment of Axin1. Axin LLPS mediates assembly of the ß-catenin destruction complex, and Dvl2 attenuates LLPS of Axin. Compared with the destruction complex, Axin partitions into the signalosome at a lower concentration and exhibits a higher mobility. Together, our results revealed that Dvl2 LLPS is crucial for controlling the assembly of the Wnt receptor signalosome and disruption of the phase-separated ß-catenin destruction complex.

Letting go: Dishevelled phase separation recruits Axin to stabilize ß-catenin.

Dishevelled exerts a molecular force that guides cell fate, but how it does so remains enigmatic. In this issue, Kang et al. (2022. J. Cell Biol.https://doi.org/10.1083/jcb.202205069) show Dvl2 undergoes liquid-liquid phase separation to stabilize ß-catenin by pulling Axin into its biomolecular condensate at the plasma membrane.

UCHL5 controls ß-catenin destruction complex function through Axin1 regulation.

Wnt/ß-catenin signaling is crucially involved in many biological processes, from embryogenesis to cancer development. Hence, the complete understanding of its molecular mechanism has been the biggest challenge in the Wnt research field. Here, we identified ubiquitin C-terminal hydrolase like 5 (UCHL5), a deubiquitinating enzyme, as a novel negative regulator of Wnt signaling, upstream of ß-catenin. The study further revealed that UCHL5 plays an important role in the ß-catenin destruction complex, as it physically interacts with multiple domains of Axin1 protein. Our functional analyses also elucidated that UCHL5 is required for both the stabilization and the polymerization of Axin1 proteins. Interestingly, although these events are governed by deubiquitination in the DIX domain of Axin1 protein, they do not require the deubiquitinating activity of UCHL5. The study proposes a novel molecular mechanism of UCHL5 potentiating the functional activity of Axin1, a scaffolder of the ß-catenin destruction complex.

Perfil de expresión de componentes del complejo de destrucción de Beta catenina en displasia oral y cáncer oral / Expression profile of components of the Beta catenin destruction complex in oral dysplasia and oral cancer

Background: Oral cancer represents the sixth most common cancer in the world and is associated with 40-50%survival at 5 years. Within oral malignancies, oral squamous cell carcinoma (OSCC) is commonly preceded bypotentially malignant lesions, which, according to histopathological criteria, are referred to as oral dysplasia andtheir diagnosis are associated with higher rates of malignant transformation towards cancer. We recently reportedthat aberrant activation of the Wnt/β catenin pathway is due to overexpression of Wnt ligands in oral dysplasia.However, the expression of other regulators of this pathway, namely components of the β-catenin destructioncomplex has not been explored in oral dysplasia.Material and Methods: Using immunohistochemical analyses, we evaluated nuclear expression of β catenin andits association with Wnt3a and Wnt5a. Likewise, components of the β-catenin destruction complex, includingAdenomatous Polyposis Coli (APC), Axin and Glycogen Synthase Kinase 3 beta (GSK-3β) were also evaluatedin oral dysplasia and OSCC biopsies.Results: We found that moderate and severe dysplasia samples, which harbored increased expression of nuclearβ catenin, depicted augmented cytoplasmic expression of GSK 3β, Axin and APC, in comparison with OSCCsamples. Also, GSK-3β was found nuclear in mild dysplasia and OSCC samples, when compared with other studysamples.Conclusions: Cytoplasmic levels of components of the β-catenin destruction complex are increased in oral dyspla-sia and might be responsible of augmented nuclear β catenin.(AU)

Expression profile of components of the ß-catenin destruction complex in oral dysplasia and oral cancer.

BACKGROUND: Oral cancer represents the sixth most common cancer in the world and is associated with 40-50% survival at 5 years. Within oral malignancies, oral squamous cell carcinoma (OSCC) is commonly preceded by potentially malignant lesions, which, according to histopathological criteria, are referred to as oral dysplasia and their diagnosis are associated with higher rates of malignant transformation towards cancer. We recently reported that aberrant activation of the Wnt/ß­catenin pathway is due to overexpression of Wnt ligands in oral dysplasia. However, the expression of other regulators of this pathway, namely components of the ß-catenin destruction complex has not been explored in oral dysplasia. MATERIAL AND METHODS: Using immunohistochemical analyses, we evaluated nuclear expression of ß­catenin and its association with Wnt3a and Wnt5a. Likewise, components of the ß-catenin destruction complex, including Adenomatous Polyposis Coli (APC), Axin and Glycogen Synthase Kinase 3 beta (GSK-3ß) were also evaluated in oral dysplasia and OSCC biopsies. RESULTS: We found that moderate and severe dysplasia samples, which harbored increased expression of nuclear ß­catenin, depicted augmented cytoplasmic expression of GSK­3ß, Axin and APC, in comparison with OSCC samples. Also, GSK-3ß was found nuclear in mild dysplasia and OSCC samples, when compared with other study samples. CONCLUSIONS: Cytoplasmic levels of components of the ß-catenin destruction complex are increased in oral dysplasia and might be responsible of augmented nuclear ß­catenin.

Dysregulation of Wnt/ß-catenin signaling by protein kinases in hepatocellular carcinoma and its therapeutic application.

Wnt/ß-catenin signaling is indispensable for many biological processes, including embryonic development, cell cycle, inflammation, and carcinogenesis. Aberrant activation of the Wnt/ß-catenin signaling can promote tumorigenicity and enhance metastatic potential in hepatocellular carcinoma (HCC). Targeting this pathway is a new opportunity for precise medicine for HCC. However, inhibiting Wnt/ß-catenin signaling alone is unlikely to significantly improve HCC patient outcome due to the lack of specific inhibitors and the complexity of this pathway. Combination with other therapies will be an important next step in improving the efficacy of Wnt/ß-catenin signaling inhibitors. Protein kinases play a key and evolutionarily conserved role in the Wnt/ß-catenin signaling and have become one of the most important drug targets in cancer. Targeting Wnt/ß-catenin signaling and its regulatory kinase together will be a promising HCC management strategy. In this review, we summarize the kinases that modulate the Wnt/ß-catenin signaling in HCC and briefly discuss their molecular mechanisms. Furthermore, we list some small molecules that target the kinases and may inhibit Wnt/ß-catenin signaling, to offer new perspectives for preclinical and clinical HCC studies.

A novel UBE2T inhibitor suppresses Wnt/ß-catenin signaling hyperactivation and gastric cancer progression by blocking RACK1 ubiquitination.

Dysregulation of the Wnt/ß-catenin signaling pathway is critically involved in gastric cancer (GC) progression. However, current Wnt pathway inhibitors being studied in preclinical or clinical settings for other cancers such as colorectal and pancreatic cancers are either too cytotoxic or insufficiently efficacious for GC. Thus, we screened new potent targets from ß-catenin destruction complex associated with GC progression from clinical samples, and found that scaffolding protein RACK1 deficiency plays a significant role in GC progression, but not APC, AXIN, and GSK3ß. Then, we identified its upstream regulator UBE2T which promotes GC progression via hyperactivating the Wnt/ß-catenin signaling pathway through the ubiquitination and degradation of RACK1 at the lysine K172, K225, and K257 residues independent of an E3 ligase. Indeed, UBE2T protein level is negatively associated with prognosis in GC patients, suggesting that UBE2T is a promising target for GC therapy. Furthermore, we identified a novel UBE2T inhibitor, M435-1279, and suggested that M435-1279 acts inhibit the Wnt/ß-catenin signaling pathway hyperactivation through blocking UBE2T-mediated degradation of RACK1, resulting in suppression of GC progression with lower cytotoxicity in the meantime. Overall, we found that increased UBE2T levels promote GC progression via the ubiquitination of RACK1 and identified a novel potent inhibitor providing a balance between growth inhibition and cytotoxicity as well, which offer a new opportunity for the specific GC patients with aberrant Wnt/ß-catenin signaling.

Endosomal Wnt signaling proteins control microtubule nucleation in dendrites.

Dendrite microtubules are polarized with minus-end-out orientation in Drosophila neurons. Nucleation sites concentrate at dendrite branch points, but how they localize is not known. Using Drosophila, we found that canonical Wnt signaling proteins regulate localization of the core nucleation protein γTubulin (γTub). Reduction of frizzleds (fz), arrow (low-density lipoprotein receptor-related protein [LRP] 5/6), dishevelled (dsh), casein kinase Iγ, G proteins, and Axin reduced γTub-green fluorescent protein (GFP) at branch points, and two functional readouts of dendritic nucleation confirmed a role for Wnt signaling proteins. Both dsh and Axin localized to branch points, with dsh upstream of Axin. Moreover, tethering Axin to mitochondria was sufficient to recruit ectopic γTub-GFP and increase microtubule dynamics in dendrites. At dendrite branch points, Axin and dsh colocalized with early endosomal marker Rab5, and new microtubule growth initiated at puncta marked with fz, dsh, Axin, and Rab5. We propose that in dendrites, canonical Wnt signaling proteins are housed on early endosomes and recruit nucleation sites to branch points.

APC controls Wnt-induced ß-catenin destruction complex recruitment in human colonocytes.

Wnt/ß-catenin signaling is essential for intestinal homeostasis and is aberrantly activated in most colorectal cancers (CRC) through mutation of the tumor suppressor Adenomatous Polyposis Coli (APC). APC is an essential component of a cytoplasmic protein complex that targets ß-catenin for destruction. Following Wnt ligand presentation, this complex is inhibited. However, a role for APC in this inhibition has not been shown. Here, we utilized Wnt3a-beads to locally activate Wnt co-receptors. In response, the endogenous ß-catenin destruction complex reoriented toward the local Wnt cue in CRC cells with full-length APC, but not if APC was truncated or depleted. Non-transformed human colon epithelial cells displayed similar Wnt-induced destruction complex localization which appeared to be dependent on APC and less so on Axin. Our results expand the current model of Wnt/ß-catenin signaling such that in response to Wnt, the ß-catenin destruction complex: (1) maintains composition and binding to ß-catenin, (2) moves toward the plasma membrane, and (3) requires full-length APC for this relocalization.

Deficiency of TGR5 exacerbates immune-mediated cholestatic hepatic injury by stabilizing the ß-catenin destruction complex.

Intrahepatic cholestasis induced by drug toxicity may cause cholestatic hepatic injury (CHI) leading to liver fibrosis and cirrhosis. The G protein-coupled bile acid receptor 1 (TGR5) is a membrane receptor with well-known roles in the regulation of glucose metabolism and energy homeostasis. However, the role and mechanism of TGR5 in the context of inflammation during CHI remains unclear. Wild-type (WT) and TGR5 knockout (TGR5-/-) mice with CHI induced by bile duct ligation (BDL) were involved in vivo, and WT and TGR5-/- bone marrow-derived macrophages (BMDMs) were used in vitro. TGR5 deficiency significantly exacerbated BDL-induced liver injury, inflammatory responses and hepatic fibrosis compared with WT mice in vivo. TGR5-/- macrophages were more susceptible to lipopolysaccharide (LPS) stimulation than WT macrophages. TGR5 activation by its ligand suppressed LPS-induced pro-inflammatory responses in WT but not TGR5-/- BMDMs. Notably, expression of ß-catenin was effectively inhibited by TGR5 deficiency. Furthermore, TGR5 directly interacted with Gsk3ß to repress the interaction between Gsk3ß and ß-catenin, thus disrupting the ß-catenin destruction complex. The pro-inflammatory nature of TGR5-knockout was almost abolished by lentivirus-mediated ß-catenin overexpression in BMDMs. BMDM migration in vitro was accelerated under TGR5-deficient conditions or supernatant from LPS-stimulated TGR5-/- BMDMs. From a therapeutic perspective, TGR5-/- BMDM administration aggravated BDL-induced CHI, which was effectively rescued by ß-catenin overexpression. Our findings reveal that TGR5 plays a crucial role as a novel regulator of immune-mediated CHI by destabilizing the ß-catenin destruction complex, with therapeutic implications for the management of human CHI.

Genetic Polymorphisms in APC, DVL2, and AXIN1 Are Associated with Susceptibility, Advanced TNM Stage or Tumor Location in Colorectal Cancer.

Colorectal cancer (CRC) is the third most common cancer and the second leading cause of death worldwide. The named "destruction complex" has a critical function in the Wnt/ß-catenin pathway regulating the level of ß-catenin in the cytoplasm and nucleus. Alterations in this complex lead to the cellular accumulation of ß-catenin, which participates in the development and progression of CRC. This study aims to determine the contribution of polymorphisms in the genes of the ß-catenin destruction complex to develop CRC, specifically adenomatous polyposis coli (APC) (rs11954856 G>T and rs459552 A>T), axis inhibition protein 1 (AXIN1) (rs9921222 C>T and rs1805105 C>T), AXIN2 (rs7224837 A>G), and dishevelled 2 (DVL2) (2074222 G>A and rs222836 C>T). Genomic DNA from 180 sporadic colorectal cancer patients and 150 healthy blood donors were analyzed. The identification of polymorphisms was made by polymerase chain reaction followed by restriction fragment length polymorphism (PCR-RFLP) methodology. Association was calculated by the odds ratio (OR) test. Increased susceptibility to CRC was associated with the polymorphic variants rs11954856 (APC), rs222836 (DVL2), and rs9921222 (AXIN1). Decreased susceptibility was associated with the polymorphisms rs459552 (APC) and 2074222 (DVL2). Association was also observed with advanced Tumor-Node-Metastasis (TNM) stages and tumor location. The haplotypes G-T in APC (rs11954856-rs459552) and A-C in DVL2 (rs2074222-rs222836) were associated with decreased risk of CRC, while the G-T haplotype in the DVL2 gene was associated with increased CRC risk. In conclusion, our results suggest that variants in the destruction complex genes may be involved in the promotion or prevention of colorectal cancer.

Destruction complex dynamics: Wnt/ß-catenin signaling alters Axin-GSK3ß interactions in vivo.

The central regulator of the Wnt/ß-catenin pathway is the Axin/APC/GSK3ß destruction complex (DC), which, under unstimulated conditions, targets cytoplasmic ß-catenin for degradation. How Wnt activation inhibits the DC to permit ß-catenin-dependent signaling remains controversial, in part because the DC and its regulation have never been observed in vivo Using bimolecular fluorescence complementation (BiFC) methods, we have now analyzed the activity of the DC under near-physiological conditions in Drosophila By focusing on well-established patterns of Wnt/Wg signaling in the developing Drosophila wing, we have defined the sequence of events by which activated Wnt receptors induce a conformational change within the DC, resulting in modified Axin-GSK3ß interactions that prevent ß-catenin degradation. Surprisingly, the nucleus is surrounded by active DCs, which principally control the degradation of ß-catenin and thereby nuclear access. These DCs are inactivated and removed upon Wnt signal transduction. These results suggest a novel mechanistic model for dynamic Wnt signal transduction in vivo.

Divergent Axin and GSK-3 paralogs in the beta-catenin destruction complexes of tapeworms.

The Wnt/beta-catenin pathway has many key roles in the development of animals, including a conserved and central role in the specification of the primary (antero-posterior) body axis. The posterior expression of Wnt ligands and the anterior expression of secreted Wnt inhibitors are known to be conserved during the larval metamorphosis of tapeworms. However, their downstream signaling components for Wnt/beta-catenin signaling have not been characterized. In this work, we have studied the core components of the beta-catenin destruction complex of the human pathogen Echinococcus multilocularis, the causative agent of alveolar echinococcosis. We focused on two Axin paralogs that are conserved in tapeworms and other flatworm parasites. Despite their divergent sequences, both Axins could robustly interact with one E. multilocularis beta-catenin paralog and limited its accumulation in a heterologous mammalian expression system. Similarly to what has been described in planarians (free-living flatworms), other beta-catenin paralogs showed limited or no interaction with either Axin and are unlikely to function as effectors in Wnt signaling. Additionally, both Axins interacted with three divergent GSK-3 paralogs that are conserved in free-living and parasitic flatworms. Axin paralogs have highly segregated expression patterns along the antero-posterior axis in the tapeworms E. multilocularis and Hymenolepis microstoma, indicating that different beta-catenin destruction complexes may operate in different regions during their larval metamorphosis.

Inhibition of TAZ contributes radiation-induced senescence and growth arrest in glioma cells.

Glioblastoma (GBM) is the most aggressive brain tumor and resistant to current available therapeutics, such as radiation. To improve the clinical efficacy, it is important to understand the cellular mechanisms underlying tumor responses to radiation. Here, we investigated long-term cellular responses of human GBM cells to ionizing radiation. Comparing to the initial response within 12 hours, gene expression modulation at 7 days after radiation is markedly different. While genes related to cell cycle arrest and DNA damage responses are mostly modulated at the initial stage; immune-related genes are specifically affected as the long-term effect. This later response is associated with increased cellular senescence and inhibition of transcriptional coactivator with PDZ-binding motif (TAZ). Mechanistically, TAZ inhibition does not depend on the canonical Hippo pathway, but relies on enhanced degradation mediated by the ß-catenin destruction complex in the Wnt pathway. We further showed that depletion of TAZ by RNAi promotes radiation-induced senescence and growth arrest. Pharmacological activation of the ß-catenin destruction complex is able to promote radiation-induced TAZ inhibition and growth arrest in these tumor cells. The correlation between senescence and reduced expression of TAZ as well as ß-catenin also occurs in human gliomas treated by radiation. Collectively, these findings suggested that inhibition of TAZ is involved in radiation-induced senescence and might benefit GBM radiotherapy.

Regulation of Transcription Factor SP1 by the ß-Catenin Destruction Complex Modulates Wnt Response.

The ubiquitous transcription factor specificity protein 1 (SP1) is heavily modified posttranslationally. These modifications are critical for switching its functions and modulation of its transcriptional activity and DNA binding and stability. However, the mechanism governing the stability of SP1 by cellular signaling pathways is not well understood. Here, we provide biochemical and functional evidence that SP1 is an integral part of the Wnt signaling pathway. We identified a phosphodegron motif in SP1 that is specific to mammals. In the absence of Wnt signaling, glycogen synthase kinase 3ß (GSK3ß)-mediated phosphorylation and ß-TrCP E3 ubiquitin ligase-mediated ubiquitination are required to induce SP1 degradation. When Wnt signaling is on, SP1 is stabilized in a ß-catenin-dependent manner. SP1 directly interacts with ß-catenin, and Wnt signaling induces the stabilization of SP1 by impeding its interaction with ß-TrCP and axin1, components of the destruction complex. Wnt signaling suppresses ubiquitination and subsequent proteosomal degradation of SP1. Furthermore, SP1 regulates Wnt-dependent stability of ß-catenin and their mutual stabilization is critical for target gene expression, suggesting a feedback mechanism. Upon stabilization, SP1 and ß-catenin cooccupy the promoters of TCFL2/ß-catenin target genes. Collectively, this study uncovers a direct link between SP1 and ß-catenin in the Wnt signaling pathway.

Supramolecular assembly of the beta-catenin destruction complex and the effect of Wnt signaling on its localization, molecular size, and activity in vivo.

Wnt signaling provides a paradigm for cell-cell signals that regulate embryonic development and stem cell homeostasis and are inappropriately activated in cancers. The tumor suppressors APC and Axin form the core of the multiprotein destruction complex, which targets the Wnt-effector beta-catenin for phosphorylation, ubiquitination and destruction. Based on earlier work, we hypothesize that the destruction complex is a supramolecular entity that self-assembles by Axin and APC polymerization, and that regulating assembly and stability of the destruction complex underlie its function. We tested this hypothesis in Drosophila embryos, a premier model of Wnt signaling. Combining biochemistry, genetic tools to manipulate Axin and APC2 levels, advanced imaging and molecule counting, we defined destruction complex assembly, stoichiometry, and localization in vivo, and its downregulation in response to Wnt signaling. Our findings challenge and revise current models of destruction complex function. Endogenous Axin and APC2 proteins and their antagonist Dishevelled accumulate at roughly similar levels, suggesting competition for binding may be critical. By expressing Axin:GFP at near endogenous levels we found that in the absence of Wnt signals, Axin and APC2 co-assemble into large cytoplasmic complexes containing tens to hundreds of Axin proteins. Wnt signals trigger recruitment of these to the membrane, while cytoplasmic Axin levels increase, suggesting altered assembly/disassembly. Glycogen synthase kinase3 regulates destruction complex recruitment to the membrane and release of Armadillo/beta-catenin from the destruction complex. Manipulating Axin or APC2 levels had no effect on destruction complex activity when Wnt signals were absent, but, surprisingly, had opposite effects on the destruction complex when Wnt signals were present. Elevating Axin made the complex more resistant to inactivation, while elevating APC2 levels enhanced inactivation. Our data suggest both absolute levels and the ratio of these two core components affect destruction complex function, supporting models in which competition among Axin partners determines destruction complex activity.

Determination of Rate-Limiting Factor for Formation of Beta-Catenin Destruction Complexes Using Absolute Protein Quantification.

Wnt/ß-catenin signaling plays important roles in both ontogenesis and development. In the absence of a Wnt stimulus, ß-catenin is degraded by a multiprotein "destruction complex" that includes Axin, APC, GSK3B, and FBXW11. Although the key molecules required for transducing Wnt signals have been identified, a quantitative understanding of this pathway has been lacking. Here, we calculated the absolute number of ß-catenin destruction complexes by absolute protein quantification using LC-MS/MS. Similar amounts of destruction complex-constituting proteins and ß-catenin interacted, and the number of destruction complexes was calculated to be about 1468 molecules/cell. We demonstrated that the calculated number of destruction complexes was valid for control of the ß-catenin destruction rate under steady-state conditions. Interestingly, APC had the minimum expression level among the destruction complex components at about 2233 molecules/cell, and this number approximately corresponded to the calculated number of destruction complexes. Decreased APC expression by siRNA transfection decreased the number of destruction complexes, resulting in ß-catenin accumulation and stimulation of the transcriptional activity of T-cell factor. Taken together, our results suggest that the amount of APC expression is the rate-limiting factor for the constitution of ß-catenin destruction complexes.

Molecular regulation and pharmacological targeting of the ß-catenin destruction complex.

The ß-catenin destruction complex is a dynamic cytosolic multiprotein assembly that provides a key node in Wnt signalling regulation. The core components of the destruction complex comprise the scaffold proteins axin and adenomatous polyposis coli and the Ser/Thr kinases casein kinase 1 and glycogen synthase kinase 3. In unstimulated cells, the destruction complex efficiently drives degradation of the transcriptional coactivator ß-catenin, thereby preventing the activation of the Wnt/ß-catenin pathway. Mutational inactivation of the destruction complex is a major pathway in the pathogenesis of cancer. Here, we review recent insights in the regulation of the ß-catenin destruction complex, including newly identified interaction interfaces, regulatory elements and post-translationally controlled mechanisms. In addition, we discuss how mutations in core destruction complex components deregulate Wnt signalling via distinct mechanisms and how these findings open up potential therapeutic approaches to restore destruction complex activity in cancer cells. LINKED ARTICLES: This article is part of a themed section on WNT Signalling: Mechanisms and Therapeutic Opportunities. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.24/issuetoc.