Biology subjects

Jordens, I.

Publications and source records attributed to Jordens, I..

8 recordsLinked to original sources

bioRxiv2025

E3 ubiquitin-ligase Hakai induces LRP4 degradation and regulates Wnt/beta-catenin signalling in colorectal cancer cells

The epithelial-mesenchymal transition (EMT) is closely linked to the acquisition of cancer stem cell (CSC) properties, which contribute to treatment resistance and metastasis. This study investigates the role of the E3 ubiquitin-ligase Hakai, the first identified post-translational regulator of E-cadherin stability, in promoting CSC traits in colorectal cancer (CRC). To examine Hakais involvement in CSC regulation, we used an inducible shRNA in a HT29 cells. Under conditions that promote CSC characteristics, we silenced Hakai and evaluated tumoursphere formation and CSC marker expression. Proteomic and bioinformatic analyses were performed to identify Hakai-regulated proteins in tumoursphere cultures. Additionally, Western blot, RT-qPCR, co-immunoprecipitation, immunofluorescence and TOPFlash assays were employed to study CSC-related protein regulation in response to Hakai expression. Furthermore, we assessed the impact of Hakin-1, the pharmacological inhibitor specifically targeting Hakais HYB domain responsible for its E3 ubiquitin-ligase activity, on tumoursphere properties. Hakai silencing significantly reduced tumoursphere size and number accompanied by decreased expression of CSC markers and Wnt target genes. CSC-related proteins regulated by Hakai were identified, including LRP4, a negative regulator of Wnt/{beta}-catenin pathway. Hakai interacts with LRP4, promoting its ubiquitination and degradation. Moreover, Hakai overexpression induces hyperactivation of Wnt/{beta}-catenin sand disrupts LRP4s inhibitory effect. Treatment with Hakin-1 effectively inhibited self-renewal and promoted differentiation within tumourspheres. These findings suggest that Hakai promotes CSCs properties by hyperactivation of the Wnt/{beta}-catenin pathway via LRP4-mediated modulation. Additionally, Hakin-1 emerges as a promising therapeutic agent targeting CSCs by enhancing differentiation and attenuating Wnt/{beta}-catenin activity, highlighting Hakai as a potential target for improving CSC treatment.

cancer biology↗

bioRxiv2025

WNK kinase regulates plasma membrane levels of the WNT inhibitor RNF43

The E3 ubiquitin ligases RNF43 and ZNRF3 are key negative regulators of canonical WNT signaling, promoting turnover of the WNT receptors FRIZZLED and LRP5/6 at the plasma membrane. While their mechanism of action is well established, how RNF43/ZNRF3 themselves are regulated remains unclear. Here, we identify WNK kinases as novel upstream regulators of RNF43 through proximity labeling proteomics. Using gain- and loss-of-function approaches, we show that WNKs control RNF43 surface localization and thereby its ability to ubiquitinate and downregulate WNT receptors. Pharmacological inhibition of WNKs increases RNF43 membrane abundance and enhances WNT suppression - an effect abolished in RNF43/ZNRF3 double knockout cells and organoids. Mechanistically, WNK inhibition alters RNF43 trafficking and ubiquitination, revealing a role for WNKs in regulating its plasma membrane distribution. These findings define a new regulatory axis linking the pro-WNT activity of WNKs to RNF43/ZNRF3-mediated feedback inhibition. Targeting WNK now offers a novel therapeutic strategy to restore WNT pathway control in cancers with RSPO fusions or RNF43 mutations.

biochemistry↗

bioRxiv2024

Hepatocellular carcinoma-associated AXIN1 mutations drive low levels of Wnt/β-catenin pathway activity that allow for niche-independent growth and YAP/TAZ signaling

In healthy cells, AXIN1 organizes assembly of a large destruction complex that mediates proteolysis of the transcriptional co-activator {beta}-catenin to prevent inappropriate Wnt/{beta}-catenin pathway activation. In hepatocellular carcinoma (HCC), AXIN1 mutations (11%) associate with a poor-prognosis subtype that is molecularly distinct from {beta}-catenin-mutant HCC (28-40%). How AXIN1 deficiency drives HCC formation has remained highly debated. Here, we address this issue by introducing HCC-associated AXIN1 and CTNNB1 mutations in human liver cancer cells and liver-derived organoids. We show that different mutant AXIN1 classes activate varying degrees of Wnt signaling, although at lower overall levels than CTNNB1 mutations. Strikingly, premature stop codons in 5 coding regions do not classify as knock-out mutations but drive alternative translation of an N-terminally truncated AXIN1 variant with partially retained suppressor activity. All AXIN1 variants endow liver progenitor organoids with the capacity to grow in the absence of R-spondin and Wnt, indicative of aberrant Wnt/{beta}-catenin pathway activation. Additionally, induced Wnt/{beta}-catenin pathway activation inversely correlates with YAP/TAZ-mediated signaling, thus leaving higher residual YAP/TAZ activity in AXIN1-mutant versus CTNNB1-mutant cells. We conclude that AXIN1 mutations drive physiologically relevant Wnt/{beta}-catenin signaling in HCC, while providing a permissive environment for YAP/YAZ signaling, thereby distinguishing AXIN1 mutations from those in CTNNB1.

cancer biology↗

bioRxiv2024

Mature tuft cell phenotypes are sequentially expressed along the intestinal crypt-villus axis following cytokine-induced tuft cell hyperplasia

Intestinal tuft cells are epithelial sentinels that trigger host defense upon detection of parasite-derived compounds. While representing interesting targets for immunomodulatory therapies in inflammation-driven intestinal diseases, their detailed functioning is poorly understood. Although two distinct intestinal tuft cell types have been described, we reveal common intermediary transcriptomes among tuft cells in mouse and human. Tuft cell-specific reporter knock-ins in organoids show that the two tuft types are sequentially expressed transcriptomic states that represent different maturation stages. Moreover, cytokines interleukin-4 and interleukin-13 only induce lineage specification to Nrep+ tuft-1 cells, while BMP and cholinergic signalling advance differentiation towards immune-related ChAT+ tuft-2 phenotypes. Functionally, both tuft cell states have chemosensory capacity and respond to stimuli like succinate, but reaction probability increases during tuft cell maturation. Our tuft type-specific reporters and optimized differentiation strategy in organoids provide an experimental platform to study the functioning of tuft cells and their unique chemosensory properties.

cell biology↗

bioRxiv2023

E3 ligases RNF43 and ZNRF3 display differential specificity for endocytosis of Frizzled family members

The transmembrane E3 ligases RNF43 and ZNRF3 perform key tumour suppressor roles by inducing endocytosis of members of the Frizzled (FZD) family, the primary receptors for WNT. Loss-of-function mutations in RNF43 and ZNRF3 mediate FZD stabilisation and a WNT-hypersensitive growth state in various cancer types. Strikingly, RNF43 and ZNRF3 mutations are differentially distributed across cancer types, raising questions about their functional redundance. Here, we compare the efficacy of RNF43 and ZNRF3 of targeting different FZDs for endocytosis. We find that RNF43 preferentially downregulates FZD1/FZD5/FZD7, while ZNRF3 displays preference towards FZD6/FZD10. We show that the RNF43 transmembrane domain (TMD) is a key molecular determinant for inducing FZD5 endocytosis. Furthermore, a TMD swap between RNF43 and ZNRF3 re-directs their preference for FZD member downregulation. We conclude that RNF43 and ZNRF3 preferentially downregulate specific FZDs by a TMD-dependent mechanism. In accordance, tissue-specific expression patterns of FZD homologues correlate with the incidence of RNF43 or ZNRF3 cancer mutations in those tissues. Consequently, our data point to druggable vulnerabilities of specific FZD receptors in RNF43- or ZNRF3-mutant human cancers.

cell biology↗

bioRxiv2023

Intestinal Paneth cell differentiation relies on asymmetric regulation of Wnt signaling by Daam1/2

The mammalian intestine is one of the most rapidly self-renewing tissues, driven by actively cycling stem cells residing at the crypt bottom1,2. Together with stromal cells, Paneth cells form a major element of the niche microenvironment that provides various growth factors to orchestrate intestinal stem cell homeostasis, such as Wnt33. With 19 family members, different Wnt ligands can selectively activate {beta}-catenin dependent (canonical) or independent (non-canonical) signaling4,5. Here, we report that Dishevelled-associated activator of morphogenesis 1 (Daam1) and its paralogue Daam2 asymmetrically regulate canonical and non-canonical Wnt (Wnt/PCP) signaling, and their function is required for Paneth cell progenitor differentiation. We found that Daam1/2 interacts with the Wnt antagonist Rnf43, and Daam1/2 double knockout stimulates canonical Wnt signaling by preventing Rnf43-dependent endo-lysosomal degradation of the ubiquitinated Wnt receptor, Frizzled (Fzd). Moreover, single-cell RNA sequencing analysis revealed that Paneth cell differentiation is impaired by Daam1/2 depletion, as a result of defective Wnt/PCP signaling. Taken together, we identified Daam1/2 as an unexpected hub molecule coordinating both canonical and non-canonical Wnt signaling, the regulation of which is fundamental for specifying an adequate number of Paneth cells while maintaining intestinal stem cell homeostasis.

cell biology↗

bioRxiv2022

RNF43 mutations facilitate mucinous colorectal cancer metastasis via formation of a tumour-intrinsic niche

Colorectal cancer (CRC) progression is characterised by a remarkable increase in plasticity and cellular heterogeneity. The ability of cells to shift states and adopt mixed lineage potential exacerbates during metastasis and associates with poor patient survival. How these atypical differentiated states emerge and drive cancer progression however has remained unclear. Here, we investigate this issue for BRAF-mutant CRC that commonly arise via the serrated pathway and are linked to poor prognosis via incompletely understood progression steps. Using patient-derived organoids, gene editing and murine tumour models, we show that mutations in RNF43, a regulator of WNT receptor abundance, endow BRAF-mutant CRC with metastatic capacity by driving a non-dividing tumour-intrinsic niche cell (TINC) state that provides growth factor self-sufficiency to the cancer tissue. TINCs are enriched in RNF43-mutant, mucinous and metastatic samples of human CRC, and ablation of TINCs lead to re-acquired external growth factor dependency during CRC organoid outgrowth. Together, our findings uncover a mechanism by which tumours leverage cellular plasticity to mediate self-organised stem- and niche-cell interactions. Our results argue that formation of a tumour-intrinsic niche is a prerequisite for BRAF-mutant CRC seeding to distant organs and that interference with niche formation may help avoid metastatic relapse.

cancer biology↗

bioRxiv2019

RNF43 truncating mutations mediate a tumour suppressor-to-oncogene switch to drive niche-independent self-renewal in cancer

Wnt/{beta}-catenin signalling is a primary pathway for stem cell maintenance during tissue renewal and a frequent target for mutations in cancer. Impaired Wnt receptor endocytosis due to loss of the ubiquitin ligase RNF43 gives rise to Wnt-hypersensitive tumours that are susceptible to anti-Wnt-based therapy. Contrary to this paradigm, we identify a class of RNF43 truncating cancer mutations that strongly induce {beta}-catenin-mediated transcription, despite exhibiting retained Wnt receptor downregulating activity. Mechanistically, these RNF43 mutants trap Casein Kinase (CK)1 at the plasma membrane, which prevents {beta}-catenin turnover and propels ligand-independent Wnt target gene transcription. When introduced in human colon stem cells, these oncogenic RNF43 mutants cooperate with p53 loss to drive a niche-independent program for self-renewal and proliferation. Importantly, onco-RNF43 mutations, unlike conventional LOF RNF43 mutations, confer resistance to anti-Wnt-based therapy. Our data demonstrate the relevance of studying patient-derived mutations for understanding disease mechanisms and improved applications of precision medicine.

cancer biology↗