WNT5B drives osteosarcoma stemness, chemoresistance and metastasis.

BACKGROUND: Treatment for osteosarcoma, a paediatric bone cancer with no therapeutic advances in over three decades, is limited by a lack of targeted therapies. Osteosarcoma frequently metastasises to the lungs, and only 20% of patients survive 5 years after the diagnosis of metastatic disease. We found that WNT5B is the most abundant WNT expressed in osteosarcoma tumours and its expression correlates with metastasis, histologic subtype and reduced survival. METHODS: Using tumor-spheroids to model cancer stem-like cells, we performed qPCR, immunoblotting, and immunofluorescence to monitor changes in gene and protein expression. Additionally, we measured sphere size, migration and forming efficiency to monitor phenotypic changes. Therefore, we characterised WNT5B's relevance to cancer stem-like cells, metastasis, and chemoresistance and evaluated its potential as a therapeutic target. RESULTS: In osteosarcoma cell lines and patient-derived spheres, WNT5B is enriched in stem cells and induces the expression of the stemness gene SOX2. WNT5B promotes sphere size, sphere-forming efficiency, and cell proliferation, migration, and chemoresistance to methotrexate (but not cisplatin or doxorubicin) in spheres formed from conventional cell lines and patient-derived xenografts. In vivo, WNT5B increased osteosarcoma lung and liver metastasis and inhibited the glycosaminoglycan hyaluronic acid via upregulation of hyaluronidase 1 (HYAL1), leading to changes in the tumour microenvironment. Further, we identified that WNT5B mRNA and protein correlate with the receptor ROR1 in primary tumours. Targeting WNT5B through inhibition of WNT/ROR1 signalling with an antibody to ROR1 reduced stemness properties, including chemoresistance, sphere size and SOX2 expression. CONCLUSIONS: Together, these data define WNT5B's role in driving osteosarcoma cancer stem cell expansion and methotrexate resistance and provide evidence that the WNT5B pathway is a promising candidate for treating osteosarcoma patients. KEY POINTS: WNT5B expression is high in osteosarcoma stem cells leading to increased stem cell proliferation and migration through SOX2. WNT5B expression in stem cells increases rates of osteosarcoma metastasis to the lungs and liver in vivo. The hyaluronic acid degradation enzyme HYAL1 is regulated by WNT5B in osteosarcoma contributing to metastasis. Inhibition of WNT5B with a ROR1 antibody decreases osteosarcoma stemness.

The Wnt-dependent master regulator NKX1-2 controls mouse pre-implantation development.

Embryo size, specification, and homeostasis are regulated by a complex gene regulatory and signaling network. Here we used gene expression signatures of Wnt-activated mouse embryonic stem cell (mESC) clones to reverse engineer an mESC regulatory network. We identify NKX1-2 as a novel master regulator of preimplantation embryo development. We find that Nkx1-2 inhibition reduces nascent RNA synthesis, downregulates genes controlling ribosome biogenesis, RNA translation, and transport, and induces severe alteration of nucleolus structure, resulting in the exclusion of RNA polymerase I from nucleoli. In turn, NKX1-2 loss of function leads to chromosome missegregation in the 2- to 4-cell embryo stages, severe decrease in blastomere numbers, alterations of tight junctions (TJs), and impairment of microlumen coarsening. Overall, these changes impair the blastocoel expansion-collapse cycle and embryo cavitation, leading to altered lineage specification and developmental arrest.

Combinatorial interpretation of BMP and WNT controls the decision between primitive streak and extraembryonic fates.

BMP signaling is essential for mammalian gastrulation, as it initiates a cascade of signals that control self-organized patterning. As development is highly dynamic, it is crucial to understand how time-dependent combinatorial signaling affects cellular differentiation. Here, we show that BMP signaling duration is a crucial control parameter that determines cell fates upon the exit from pluripotency through its interplay with the induced secondary signal WNT. BMP signaling directly converts cells from pluripotent to extraembryonic fates while simultaneously upregulating Wnt signaling, which promotes primitive streak and mesodermal specification. Using live-cell imaging of signaling and cell fate reporters together with a simple mathematical model, we show that this circuit produces a temporal morphogen effect where, once BMP signal duration is above a threshold for differentiation, intermediate and long pulses of BMP signaling produce specification of mesoderm and extraembryonic fates, respectively. Our results provide a systems-level picture of how these signaling pathways control the landscape of early human development.

Noncanonical WNT5A controls the activation of latent TGF-ß to drive fibroblast activation and tissue fibrosis.

Transforming growth factor ß (TGF-ß) signaling is a core pathway of fibrosis, but the molecular regulation of the activation of latent TGF-ß remains incompletely understood. Here, we demonstrate a crucial role of WNT5A/JNK/ROCK signaling that rapidly coordinates the activation of latent TGF-ß in fibrotic diseases. WNT5A was identified as a predominant noncanonical WNT ligand in fibrotic diseases such as systemic sclerosis, sclerodermatous chronic graft-versus-host disease, and idiopathic pulmonary fibrosis, stimulating fibroblast-to-myofibroblast transition and tissue fibrosis by activation of latent TGF-ß. The activation of latent TGF-ß requires rapid JNK- and ROCK-dependent cytoskeletal rearrangements and integrin αV (ITGAV). Conditional ablation of WNT5A or its downstream targets prevented activation of latent TGF-ß, rebalanced TGF-ß signaling, and ameliorated experimental fibrosis. We thus uncovered what we believe to be a novel mechanism for the aberrant activation of latent TGF-ß in fibrotic diseases and provided evidence for targeting WNT5A/JNK/ROCK signaling in fibrotic diseases as a new therapeutic approach.

The Clock and Wavefront Self-Organizing model recreates the dynamics of mouse somitogenesis in vivo and in vitro.

During mouse development, presomitic mesoderm cells synchronize Wnt and Notch oscillations, creating sequential phase waves that pattern somites. Traditional somitogenesis models attribute phase waves to a global modulation of the oscillation frequency. However, increasing evidence suggests that they could arise in a self-organizing manner. Here, we introduce the Sevilletor, a novel reaction-diffusion system that serves as a framework to compare different somitogenesis patterning hypotheses. Using this framework, we propose the Clock and Wavefront Self-Organizing model that considers an excitable self-organizing region where phase waves form independent of global frequency gradients. The model recapitulates the change in relative phase of Wnt and Notch observed during mouse somitogenesis and provides a theoretical basis for understanding the excitability of mouse presomitic mesoderm cells in vitro.

Frizzleds act as dynamic pharmacological entities.

The Frizzled family of transmembrane receptors (FZD1-10) belongs to the class F of G protein-coupled receptors (GPCRs). FZDs bind to and are activated by Wingless/Int1 (WNT) proteins. The WNT/FZD signaling system regulates crucial aspects of developmental biology and stem-cell regulation. Dysregulation of WNT/FZD communication can lead to developmental defects and diseases such as cancer and fibrosis. Recent insight into the activation mechanisms of FZDs has underlined that protein dynamics and conserved microswitches are essential for FZD-mediated information flow and build the basis for targeting these receptors pharmacologically. In this review, we summarize recent advances in our understanding of FZD activation, and how novel concepts merge and collide with existing dogmas in the field.

Characterization and impact of non-canonical WNT signaling on outcomes of urothelial carcinoma.

BACKGROUND: Non-canonical WNT family (WNT5A pathway) signaling via WNT5A through ROR1 and its partner, ROR2, or Frizzled2 (FZD2) is linked to processes driving tumorigenesis and therapy resistance. We utilized a large dataset of urothelial carcinoma (UC) tumors to characterize non-canonical WNT signaling through WNT5A, ROR1, ROR2, or FZD2 expression. METHODS: NextGen Sequencing of DNA (592 genes or WES)/RNA (WTS) was performed for 4125 UC tumors submitted to Caris Life Sciences. High and low expression of WNT5A, ROR1, ROR2, and FZD2 was defined as ≥ top and

A brain-specific angiogenic mechanism enabled by tip cell specialization.

Vertebrate organs require locally adapted blood vessels1,2. The gain of such organotypic vessel specializations is often deemed to be molecularly unrelated to the process of organ vascularization. Here, opposing this model, we reveal a molecular mechanism for brain-specific angiogenesis that operates under the control of Wnt7a/b ligands-well-known blood-brain barrier maturation signals3-5. The control mechanism relies on Wnt7a/b-dependent expression of Mmp25, which we find is enriched in brain endothelial cells. CRISPR-Cas9 mutagenesis in zebrafish reveals that this poorly characterized glycosylphosphatidylinositol-anchored matrix metalloproteinase is selectively required in endothelial tip cells to enable their initial migration across the pial basement membrane lining the brain surface. Mechanistically, Mmp25 confers brain invasive competence by cleaving meningeal fibroblast-derived collagen IV α5/6 chains within a short non-collagenous region of the central helical part of the heterotrimer. After genetic interference with the pial basement membrane composition, the Wnt-ß-catenin-dependent organotypic control of brain angiogenesis is lost, resulting in properly patterned, yet blood-brain-barrier-defective cerebrovasculatures. We reveal an organ-specific angiogenesis mechanism, shed light on tip cell mechanistic angiodiversity and thereby illustrate how organs, by imposing local constraints on angiogenic tip cells, can select vessels matching their distinctive physiological requirements.

Differential changes in Wnt7 and Dkk1 levels in astrocytes exposed to glutamate or TNFα.

Wnt signaling plays an important role in adult brain function, and its dysregulation has been implicated in the loss of neuronal homeostasis. Despite the existence of many studies on the participation of the Wnt pathway in adult neurons, its regulation in astrocytes has been scarcely explored. Several reports point to the presence of Wnt ligands in astrocytes and their possible impact on neuronal plasticity or neuronal death. We aimed to analyze the effect of the neurotransmitter glutamate and the inflammatory cytokine TNFα on the mRNA and protein levels of the canonical Wnt agonist Wnt7a and the antagonist Dkk1 in cultured astrocytes. Primary astrocyte cultures from rat cerebral cortices were exposed to glutamate or TNFα. Wnt7a and Dkk1 expression was analyzed by RT-qPCR and its protein abundance and distribution was assessed by immunofluorescence. We found high basal expression and protein levels of Wnt7a and Dkk1 in unstimulated astrocytes and overproduction of Dkk1 mRNA induced by the two stimuli. These results reveal the astrocytic source of the canonical Wnt ligands Wnt7a and Dkk1, whose levels are differentially regulated by glutamate and TNFα. Astrocytes are a significant source of Wnt ligands, the production of which can be differentially regulated under excitatory or proinflammatory conditions, thereby impacting neuronal function.

The pRb/RBL2-E2F1/4-GCN5 axis regulates cancer stem cell formation and G0 phase entry/exit by paracrine mechanisms.

The lethality, chemoresistance and metastatic characteristics of cancers are associated with phenotypically plastic cancer stem cells (CSCs). How the non-cell autonomous signalling pathways and cell-autonomous transcriptional machinery orchestrate the stem cell-like characteristics of CSCs is still poorly understood. Here we use a quantitative proteomic approach for identifying secreted proteins of CSCs in pancreatic cancer. We uncover that the cell-autonomous E2F1/4-pRb/RBL2 axis balances non-cell-autonomous signalling in healthy ductal cells but becomes deregulated upon KRAS mutation. E2F1 and E2F4 induce whereas pRb/RBL2 reduce WNT ligand expression (e.g. WNT7A, WNT7B, WNT10A, WNT4) thereby regulating self-renewal, chemoresistance and invasiveness of CSCs in both PDAC and breast cancer, and fibroblast proliferation. Screening for epigenetic enzymes identifies GCN5 as a regulator of CSCs that deposits H3K9ac onto WNT promoters and enhancers. Collectively, paracrine signalling pathways are controlled by the E2F-GCN5-RB axis in diverse cancers and this could be a therapeutic target for eliminating CSCs.

Toll-like receptor-2 induced inflammation causes local bone formation and activates canonical Wnt signaling.

It is well established that inflammatory processes in the vicinity of bone often induce osteoclast formation and bone resorption. Effects of inflammatory processes on bone formation are less studied. Therefore, we investigated the effect of locally induced inflammation on bone formation. Toll-like receptor (TLR) 2 agonists LPS from Porphyromonas gingivalis and PAM2 were injected once subcutaneously above mouse calvarial bones. After five days, both agonists induced bone formation mainly at endocranial surfaces. The injection resulted in progressively increased calvarial thickness during 21 days. Excessive new bone formation was mainly observed separated from bone resorption cavities. Anti-RANKL did not affect the increase of bone formation. Inflammation caused increased bone formation rate due to increased mineralizing surfaces as assessed by dynamic histomorphometry. In areas close to new bone formation, an abundance of proliferating cells was observed as well as cells robustly stained for Runx2 and alkaline phosphatase. PAM2 increased the mRNA expression of Lrp5, Lrp6 and Wnt7b, and decreased the expression of Sost and Dkk1. In situ hybridization demonstrated decreased Sost mRNA expression in osteocytes present in old bone. An abundance of cells expressed Wnt7b in Runx2-positive osteoblasts and ß-catenin in areas with new bone formation. These data demonstrate that inflammation, not only induces osteoclastogenesis, but also locally activates canonical WNT signaling and stimulates new bone formation independent on bone resorption.

EGFR-dependent endocytosis of Wnt9a and Fzd9b promotes ß-catenin signaling during hematopoietic stem cell development in zebrafish.

Cell-to-cell communication through secreted Wnt ligands that bind to members of the Frizzled (Fzd) family of transmembrane receptors is critical for development and homeostasis. Wnt9a signals through Fzd9b, the co-receptor LRP5 or LRP6 (LRP5/6), and the epidermal growth factor receptor (EGFR) to promote early proliferation of zebrafish and human hematopoietic stem cells during development. Here, we developed fluorescently labeled, biologically active Wnt9a and Fzd9b fusion proteins to demonstrate that EGFR-dependent endocytosis of the ligand-receptor complex was required for signaling. In human cells, the Wnt9a-Fzd9b complex was rapidly endocytosed and trafficked through early and late endosomes, lysosomes, and the endoplasmic reticulum. Using small-molecule inhibitors and genetic and knockdown approaches, we found that Wnt9a-Fzd9b endocytosis required EGFR-mediated phosphorylation of the Fzd9b tail, caveolin, and the scaffolding protein EGFR protein substrate 15 (EPS15). LRP5/6 and the downstream signaling component AXIN were required for Wnt9a-Fzd9b signaling but not for endocytosis. Knockdown or loss of EPS15 impaired hematopoietic stem cell development in zebrafish. Other Wnt ligands do not require endocytosis for signaling activity, implying that specific modes of endocytosis and trafficking may represent a method by which Wnt-Fzd specificity is established.

miR-199a-5p modulates choroidal neovascularization by regulating Wnt7b/Wnt/ß-catenin signaling pathway.

Choroidal neovascularization (CNV) can be seen in many fundus diseases, and lead to fundus exudation, bleeding, or vision loss. miRNAs are vital regulator in CNV. miR-199a-5p has been proved to be involved in regulating vascular formation of endothelial cells, but its role in CNV remains unclear. This study aims to study the role of miR-199a-5p in CNV. Laser irradiation was used to induce CNV model. The lesion area of CNV was calculated by high-resolution angiography with fluorescein isothiocyanate-dextran. Wnt family member 7b (Wnt7b), ß-catenin, and Wnt pathway proteins was measured by western blot. Immunofluorescence was performed to test Wnt7b, ß-catenin, CD31, and p-p65. miR-199a-5p and Wnt7b mRNA were tested by reverse transcription real-time polymerase chain reaction. Cell count kit-8, wound healing, Transwell, tube formation, and flow cytometry were used to detect the function of miR-199a-5p and Wnt7b on human retinal microvascular endothelial cells (HRMEC). TargetScan database and dual-luciferase reporter assay verified the interaction between miR-199a-5p and Wnt7b. The results revealed that Wnt7b increased in CNV rats. Knocking down Wnt7b repressed cell proliferation, migration, invasion, and angiogenesis, and accelerated cell apoptosis of HRMEC. Dual-luciferase reporter assay verified that miR-199a-5p targeted Wnt7b. Overexpression of miR-199a-5p inhibited the angiogenesis of HRMEC and promoted cell apoptosis by inhibiting Wbt7b. In vivo experiment found that Wnt7b rescued the promotion of miR-199a-5p inhibition on CNV lesion of rats. In addition, Wnt7b positively regulated Wnt/ß-catenin signaling pathway and promoted the angiogenesis of HRMEC. In conclusion, overexpression of miR-199a-5p inhibited the angiogenesis of HRMEC by regulating Wnt7b/Wnt/ß-catenin signaling pathway, which may serve as a promising therapy target of CNV.

Single-cell RNA-seq analysis reveals the Wnt/Ca2+ signaling pathway with inflammation, apoptosis in nucleus pulposus degeneration.

BACKGROUND: Increasing studies have shown degeneration of nucleus pulposus cells (NPCs) as an critical part of the progression of intervertebral disc degeneration (IVDD). However, there are relatively few studies on single-cell transcriptome contrasts in human degenerated NPCs. Moreover, differences in Wnt/Ca2+ signaling in human degenerated nucleus pulposus cells have not been elucidated. The aim of this study is to investigate the differential expression of Wnt/Ca2+ signaling pathway between normal and degenerated nucleus pulposus cells in humans and try to investigate its mechanism. METHODS: We performed bioinformatics analysis using our previously published findings to construct single cell expression profiles of normal and degenerated nucleus pulposus. Then, in-depth differential analysis was used to characterize the expression of Wnt/Ca2+ signaling pathway between normal and degenerated nucleus pulposus cells in humans. RESULTS: The obtained cell data were clustered into five different chondrocytes clusters, which chondrocyte 4 and chondrocyte 5 mainly accounted for a high proportion in degenerated nucleus pulposus tissues, but rarely in normal nucleus pulposus tissues. Genes associated within the Wnt/Ca2+ signaling pathway, such as Wnt5B, FZD1, PLC (PLCB1), CaN (PPP3CA) and NAFATC1 are mainly present in chondrocyte 3, chondrocyte 4 and chondrocyte 5 from degenerated nucleus pulposus tissues. In addition, as a receptor that activates Wnt signaling pathway, LRP5 is mainly highly expressed in chondrocyte 5 of degenerated nucleus pulposus cells. Six genes, ANGPTL4, PTGES, IGFBP3, GDF15, TRIB3 and TNFRSF10B, which are associated with apoptosis and inflammatory responses, and are widespread in chondrocyte 4 and chondrocyte 5, may be closely related to degenerative of nucleus pulposus cells. CONCLUSIONS: Single-cell RNA sequencing revealed differential expression of Wnt/Ca2+ signaling in human normal and degenerated nucleus pulposus cells, and this differential expression may be closely related to the abundance of chondrocyte 4 and chondrocyte 5 in degenerated nucleus pulposus cells. In degenerated nucleus pulposus cells, LRP5 activate Wnt5B, which promotes nucleus pulposus cell apoptosis and inflammatory response by regulating the Wnt/Ca2+ signaling pathway, thereby promoting disc degeneration. ANGPTL4, IGFBP3, PTGES in chondrocyte 4 and TRIB3, GDF15, TNFRSF10B in chondrocyte 5 may play an important role in this process.

Transfer of polarity information via diffusion of Wnt ligands in C. elegans embryos.

Different signaling mechanisms concur to ensure robust tissue patterning and cell fate instruction during animal development. Most of these mechanisms rely on signaling proteins that are produced, transported, and detected. The spatiotemporal dynamics of signaling molecules are largely unknown, yet they determine signal activity's spatial range and time frame. Here, we use the Caenorhabditis elegans embryo to study how Wnt ligands, an evolutionarily conserved family of signaling proteins, dynamically organize to establish cell polarity in a developing tissue. We identify how Wnt ligands, produced in the posterior half of the embryos, spread extracellularly to transmit information to distant target cells in the anterior half. With quantitative live imaging and fluorescence correlation spectroscopy, we show that Wnt ligands diffuse through the embryo over a timescale shorter than the cell cycle, in the intercellular space, and outside the tissue below the eggshell. We extracted diffusion coefficients of Wnt ligands and their receptor Frizzled and characterized their co-localization. Integrating our different measurements and observations in a simple computational framework, we show how fast diffusion in the embryo can polarize individual cells through a time integration of the arrival of the ligands at the target cells. The polarity established at the tissue level by a posterior Wnt source can be transferred to the cellular level. Our results support a diffusion-based long-range Wnt signaling, which is consistent with the dynamics of developing processes.

SFRP2 suppresses trophoblast cell migration by inhibiting the Wnt/ß­catenin pathway.

The present study investigates the role of Secreted Frizzled­Related Protein 2 (SFRP2) in trophoblast cells, a key factor in preeclampsia (PE) progression. Elevated levels of Secreted Frizzled­Related Protein 1/3/4/5 (SFRP1/3/4/5) are associated with PE, but the role of SFRP2 is unclear. We analyzed SFRP2 expression in PE placental tissue using the GSE10588 dataset and overexpressed SFRP2 in JEG­3 cells via lentiviral transfection. The viability, migration, apoptosis, and proliferation of SFRP2­overexpressing JEG­3 cells were assessed using Cell Counting Kit­8, Transwell assays, flow cytometry, and EdU staining. Additionally, we evaluated the impact of SFRP2 overexpression on key proteins in the Wnt/ß­catenin pathway and apoptosis markers (Bax, cleaved­caspase 3, BCL­2, MMP9, E­cadherin, Wnt3a, Axin2, CyclinD1, c­Myc, p­ß­catenin, ß­catenin, phosphorylated Glycogen Synthase Kinase 3 beta (p­GSK3ß), and GSK3ß) through western blotting. Results showed high SFRP2 mRNA and protein expression in PE placenta and JEG­3 cells post­transfection. SFRP2 overexpression significantly reduced JEG­3 cell viability, proliferation, and migration, while increasing apoptosis. It also altered expression levels of Wnt pathway proteins, suggesting SFRP2's potential as a therapeutic target for PE by inhibiting trophoblast cell migration through the Wnt/ß­catenin signaling cascade.

A Wnt10a-Notch signaling axis controls Hertwig's epithelial root sheath cell behaviors during root furcation patterning.

Human with bi-allelic WNT10A mutations and epithelial Wnt10a knockout mice present enlarged pulp chamber and apical displacement of the root furcation of multi-rooted teeth, known as taurodontism; thus, indicating the critical role of Wnt10a in tooth root morphogenesis. However, the endogenous mechanism by which epithelial Wnt10a regulates Hertwig's epithelial root sheath (HERS) cellular behaviors and contributes to root furcation patterning remains unclear. In this study, we found that HERS in the presumptive root furcating region failed to elongate at an appropriate horizontal level in K14-Cre;Wnt10afl/fl mice from post-natal day 0.5 (PN0.5) to PN4.5. EdU assays and immunofluorescent staining of cyclin D1 revealed significantly decreased proliferation activity of inner enamel epithelial (IEE) cells of HERS in K14-Cre;Wnt10afl/fl mice at PN2.5 and PN3.5. Immunofluorescent staining of E-Cadherin and acetyl-α-Tubulin demonstrated that the IEE cells of HERS tended to divide perpendicularly to the horizontal plane, which impaired the horizontal extension of HERS in the presumptive root furcating region of K14-Cre;Wnt10afl/fl mice. RNA-seq and immunofluorescence showed that the expressions of Jag1 and Notch2 were downregulated in IEE cells of HERS in K14-Cre;Wnt10afl/fl mice. Furthermore, after activation of Notch signaling in K14-Cre;Wnt10afl/fl molars by Notch2 adenovirus and kidney capsule grafts, the root furcation defect was partially rescued. Taken together, our study demonstrates that an epithelial Wnt10a-Notch signaling axis is crucial for modulating HERS cell proper proliferation and horizontal-oriented division during tooth root furcation morphogenesis.

WNT2B activates macrophages via NF-κB signaling pathway in inflammatory bowel disease.

Inflammation is a significant pathological manifestation of inflammatory bowel disease (IBD), yet its mechanism has remained unclear. Although WNT2B is enriched in the intestinal inflammatory tissue of IBD patients, the specific mechanism of WNT2B in the formation of intestinal inflammation remains unclear. This study was aimed to investigate whether macrophages expressing WNT2B can aggravate intestinal tissue inflammation. Samples were collected from both normal individuals and patients with IBD at multiple colon sites. Macrophages were identified using tissue immunofluorescence. IκB kinase (IKK)-interacting protein (IKIP), which interacts with WNT2B, was found by protein cross-linking and protein mass spectrometry. The expression of WNT2B, IKIP, the NF-κB pathway, and downstream molecules were analyzed. An acute colitis model of C57BL/6J mice was established using an adeno-associated virus (AAV)-mediated WNT2B knockdown system and 3% dextran sulfate sodium (DSS). The degree of intestinal inflammation in mice was assessed upon WNT2B knockdown in macrophages. Macrophages expressing WNT2B were found to be enriched in the colitis tissues of IBD patients. WNT2B in macrophages activated the NF-κB pathway and enhanced the expression of downstream inflammatory cytokines. By competitively binding IKIP, WNT2B reduced the binding of IKIP to IKKß and promoted the activation of the NF-κB pathway. Using an AAV-mediated WNT2B knockdown system, WNT2B expression in intestinal macrophages was suppressed, leading to a reduction in intestinal inflammation. WNT2B activated the NF-κB pathway and enhanced the expression of downstream inflammatory cytokines by competitively binding to IKIP, potentially contributing to colon inflammatory injury in IBD.

Transport and gradient formation of Wnt and Fgf in the early zebrafish gastrula.

Within embryonic development, the occurrence of gastrulation is critical in the formation of multiple germ layers with many differentiative abilities. These cells are instructed through exposure to signalling molecules called morphogens. The secretion of morphogens from a source tissue creates a concentration gradient that allows distinct pattern formation in the receiving tissue. This review focuses on the morphogens Wnt and Fgf in zebrafish development. Wnt has been shown to have critical roles throughout gastrulation, including in anteroposterior patterning and neural posterisation. Fgf is also a vital signal, contributing to involution and mesodermal specification. Both morphogens have also been found to work in finely balanced synergy for processes such as neural induction. Thus, the signalling range of Wnts and Fgfs must be strictly controlled to target the correct target cells. Fgf and Wnts signal to local cells as well as to cells in the distance in a highly regulated way, requiring specific dissemination mechanisms that allow efficient and precise signalling over short and long distances. Multiple transportation mechanisms have been discovered to aid in producing a stable morphogen gradient, including short-range diffusion, filopodia-like extensions called cytonemes and extracellular vesicles, mainly exosomes. These mechanisms are specific to the morphogen that they transport and the intended signalling range. This review article discusses how spreading mechanisms in these two morphogenetic systems differ and the consequences on paracrine signalling, hence tissue patterning.

Competence for neural crest induction is controlled by hydrostatic pressure through Yap.

Embryonic induction is a key mechanism in development that corresponds to an interaction between a signalling and a responding tissue, causing a change in the direction of differentiation by the responding tissue. Considerable progress has been achieved in identifying inductive signals, yet how tissues control their responsiveness to these signals, known as competence, remains poorly understood. While the role of molecular signals in competence has been studied, how tissue mechanics influence competence remains unexplored. Here we investigate the role of hydrostatic pressure in controlling competence in neural crest cells, an embryonic cell population. We show that neural crest competence decreases concomitantly with an increase in the hydrostatic pressure of the blastocoel, an embryonic cavity in contact with the prospective neural crest. By manipulating hydrostatic pressure in vivo, we show that this increase leads to the inhibition of Yap signalling and impairs Wnt activation in the responding tissue, which would be required for neural crest induction. We further show that hydrostatic pressure controls neural crest induction in amphibian and mouse embryos and in human cells, suggesting a conserved mechanism across vertebrates. Our work sets out how tissue mechanics can interplay with signalling pathways to regulate embryonic competence.