Activation Of Wnt Pathway Research Articles

DOP111 Lack of epithelial RhoA in the gut, a new colitis-associated cancer experimental model

Abstract Background The small GTPase RhoA controls cytoskeleton dynamics in various cell types, including intestinal epithelial cells (IECs). Accordingly, we have shown that lack of RhoA in IECs in mice increases intestinal permeability and inflammation1. However, its role in cancer is controversial. While classically recognized as a potential colorectal cancer (CRC) biomarker2, RhoA inactivation was found to increase Wnt signalling and tumor risk in mouse small intestinal epithelium3. Additionally, proteins in the RhoA/Rac1 pathway were identified as highly mutated in human colitis-associated cancer (CAC)4. We hypothesize that a finely tuned RhoA function in IECs determines CRC risk and that inflammation might modulate RhoA´s pro- or anti-tumor effects in the gut. Methods RhoAΔIEC mice generated using the loxPCre system were our main model1. We monitored disease progression, analysed the transcriptome in colon and tumoral tissue (bulk RNA-sequencing), assessed microbiota composition (16S rRNA gene sequencing), and conducted in vitro colon organoids studies. Moreover, Rho/Rac-associated proteins were analysed across colorectal cancer (CRC) and colitis associated cancer (CAC) mouse models. Results RhoAΔIEC mice developed chronic intestinal inflammation and spontaneous colon tumorigenesis. Bulk RNA sequencing and Gene Set Enrichment Analysis (GSEA) highlighted four regulated pathways: inflammation, microbiota, proliferation, and epithelial-mesenchymal transition (EMT). Transcriptomic changes showed similarities with the azoxymethane/dextran sulphate sodium (AOM/DSS) and APCmin models. Microbiota analysis showed altered β-diversity, with higher abundance of Mycoplasma and Helicobacter genus. Increased Ki67 expression and non-phospho β-catenin indicated Wnt pathway activation, while YAP was not upregulated. RhoA deficient cells showed signs of EMT, as decreased E cadherin expression. Moreover, tumors in RhoAΔIEC mice depicted increased expression of CXCR2-axis chemokines (Cxcl1, 2, 5) and neutrophil infiltration. Among candidate Rho/Rac related proteins, qPCR showed DOCK2 upregulation in AOM and AOM/DSS while Prex2 increased exclusively in AOM/DSS model; DOCK3 and Radil were not regulated. Conclusion Lack of RhoA in IECs drives sustained intestinal inflammation and spontaneous tumorigenesis through Wnt-dependent proliferation, EMT, neutrophil activation, and dysbiosis. RhoAΔIEC mice represent a novel model of inflammation-associated tumorigenesis in the gut. Translationally, the Rac/Rho-associated PREX2 emerges as a candidate CAC-specific biomarker. We hypothesize that PREX2 increases to compensate for RhoA during inflammation.

Icariin Facilitates Osteogenic Differentiation and Suppresses Adipogenic Differentiation of Bone Marrow Mesenchymal Stem Cells by Enhancing SOST Methylation in Postmenopausal Osteoporosis.

Postmenopausal osteoporosis (PMO) is mainly concerned with the imbalance of bone resorption and bone formation. Icariin (ICA) plays a vital role in bone protection. This study investigated the mechanism of ICA in PMO rats. The rats were treated with ovariectomy (OVX) and ICA. Bone structure parameters were measured by Micro-CT. BMSCs were obtained from normal rats, OVX rats, and ICA-treated rats. BMSCs were infected with SOST overexpression lentivirus, and TWS119, an activator of Wnt pathway, was introduced for joint experiment. The binding of ERα to SOST promoter was verified. OVX/ICA rats were injected with DNA methyltransferase inhibitor 5-Aza-dC. ICA increased bone mass and decreased bone marrow fat content in OVX rats. ICA facilitated osteogenic differentiation and repressed adipogenic differentiation of BMSCs. Overexpressing SOST antagonized the effect of ICA, whereas TWS119 rescued the effect of overexpressing SOST. ICA reduced SOST expression by attenuating the effect of ERα. Methylation of SOST inhibited ERα binding to SOST promoter. Invivo experiments confirmed that ICA improved bone mass and reduced bone marrow fat content by enhancing SOST methylation. Overall, ICA upregulated SOST methylation and inhibited the binding of ERα to SOST promoter, thereby promoting osteogenic differentiation and repressing adipogenic differentiation of BMSCs.

M6A Reader PRRC2A Promotes Colorectal Cancer Progression via CK1ε-Mediated Activation of WNT and YAP Signaling Pathways.

Colorectal cancer (CRC) is the third most common cancer type and the second highest mortality rate among cancers. However, the mechanisms underlying CRC progression remain to be fully understood. In this work, a recently identified m6A-modified RNA reader protein Proline-rich Coiled-coil 2a (PRRC2A)is markedly upregulated in CRC, and intestinal epithelium-specific deletion of Prrc2a significantly suppressed tumor cell growth, stemness, and migratory capacity, while its overexpression promoted these behaviors. Through multiomics analysis, PRRC2A directly targeted CSNK1E (encoding CK1ε), maintaining its RNA stability in an m6A-dependent manner, and that elevated CK1ε can concomitantly result in activation of the WNT and YAP signaling pathways. Interestingly, PRRC2A is directly regulated by the transcription factor ATF1 in its promoter. In summary, the work reveals a novel mechanism by which m6A reader PRRC2A promotes colorectal cancer progression via CK1ε and aberrant upregulation of WNT and YAP signaling. Therefore, PRRC2A and CK1ε can be potential therapeutic targets for treating CRC.

Timely TGFβ signalling inhibition induces notochord

The formation of the vertebrate body involves the coordinated production of trunk tissues from progenitors located in the posterior of the embryo. Although in vitro models using pluripotent stem cells replicate aspects of this process1, 2, 3, 4, 5, 6, 7, 8, 9–10, they lack crucial components, most notably the notochord—a defining feature of chordates that patterns surrounding tissues11. Consequently, cell types dependent on notochord signals are absent from current models of human trunk formation. Here we performed single-cell transcriptomic analysis of chick embryos to map molecularly distinct progenitor populations and their spatial organization. Guided by this map, we investigated how differentiating human pluripotent stem cells develop a stereotypical spatial organization of trunk cell types. We found that YAP inactivation in conjunction with FGF-mediated MAPK signalling facilitated WNT pathway activation and induced expression of TBXT (also known as BRA). In addition, timely inhibition of WNT-induced NODAL and BMP signalling regulated the proportions of different tissue types, including notochordal cells. This enabled us to create a three-dimensional model of human trunk development that undergoes morphogenetic movements, producing elongated structures with a notochord and ventral neural and mesodermal tissues. Our findings provide insights into the mechanisms underlying vertebrate notochord formation and establish a more comprehensive in vitro model of human trunk development. This paves the way for future studies of tissue patterning in a physiologically relevant environment.

In vitro modelling of anterior primitive streak patterning with human pluripotent stem cells identifies the path to notochord progenitors.

Notochord progenitors (NotoPs) represent a scarce yet crucial embryonic cell population, playing important roles in embryo patterning and eventually giving rise to the cells that form and maintain intervertebral discs. The mechanisms regulating NotoPs emergence are unclear. This knowledge gap persists due to the inherent complexity of cell fate patterning during gastrulation, particularly within the anterior primitive streak (APS), where NotoPs first arise alongside neuro-mesoderm and endoderm. To gain insights into this process, we use micropatterning together with FGF and the WNT pathway activator CHIR9901 to guide the development of human embryonic stem cells into reproducible patterns of APS cell fates. We show that CHIR9901 dosage dictates the downstream dynamics of endogenous TGFβ signalling, which in turn controls cell fate decisions. While sustained NODAL signalling defines endoderm and NODAL inhibition is imperative for neuro-mesoderm emergence, timely inhibition of NODAL signalling with spatial confinement potentiates WNT activity and enables us to generate NotoPs efficiently. Our work elucidates the signalling regimes underpinning NotoP emergence and provides insights into the regulatory mechanisms controlling the balance of APS cell fates during gastrulation.

Loss of AXIN1 regulates response to lenvatinib through a WNT/KDM5B/p15 signalling axis in hepatocellular carcinoma.

As a highly heterogeneous cancer, hepatocellular carcinoma (HCC) shows different response rates to the multi-kinase inhibitor lenvatinib. Thus, it is important to explore genetic biomarkers for precision lenvatinib therapy in HCC. The effect and mechanism of AXIN1 mutation on HCC were revealed by cell proliferation assay, long-term clone formation assay, sphere formation assay and small molecule inhibitor library screening. A new therapeutic strategy targeting HCC with AXIN1 mutation was evaluated in humanized models (patient-derived xenograft [PDX] and patient-derived organoid [PDO]). Based on The Cancer Genome Atlas (TCGA) data, we screened 6 most frequently lost tumour suppressor genes in HCC (TP53, ARID1A, AXIN1, CDKN2A, ARID2 and PTEN) and identified AXIN1 as the most crucial gene for lenvatinib sensitivity. Further study showed that AXIN1-knockout HCC cells had a more malignant phenotype and lower sensitivity to lenvatinib in vitro and in vivo. Mechanistically, the WNT pathway and its target gene c-Myc were activated when AXIN1 was missing, and the expression of tumour suppressor p15 was inhibited by transcription co-repressors c-Myc and Miz-1, resulting in the exacerbation of the resistant phenotype. Screening of a library of epigenetic-related enzyme inhibitors showed that a KDM5B inhibitor up-regulated p15 expression, leading to increased sensitivity to lenvatinib in vitro and in vivo. AXIN1-deficient patients have a lower response to lenvatinib, which may be associated with suppression of p15 mediated by WNT pathway activation. KDM5B inhibitors can restore p15 levels, resulting in efficient killing of resistant cells in HCC.

Endogenous oligomer formation underlies DVL2 condensates and promotes Wnt/β-catenin signaling

Activation of the Wnt/β-catenin pathway crucially depends on the polymerization of dishevelled 2 (DVL2) into biomolecular condensates. However, given the low affinity of known DVL2 self-interaction sites and its low cellular concentration, it is unclear how polymers can form. Here, we detect oligomeric DVL2 complexes at endogenous protein levels in human cell lines, using a biochemical ultracentrifugation assay. We identify a low-complexity region (LCR4) in the C-terminus whose deletion and fusion decreased and increased the complexes, respectively. Notably, LCR4-induced complexes correlated with the formation of microscopically visible multimeric condensates. Adjacent to LCR4, we mapped a conserved domain (CD2) promoting condensates only. Molecularly, LCR4 and CD2 mediated DVL2 self-interaction via aggregating residues and phenylalanine stickers, respectively. Point mutations inactivating these interaction sites impaired Wnt pathway activation by DVL2. Our study discovers DVL2 complexes with functional importance for Wnt/β-catenin signaling. Moreover, we provide evidence that DVL2 condensates form in two steps by pre-oligomerization via high-affinity interaction sites, such as LCR4, and subsequent condensation via low-affinity interaction sites, such as CD2.

Endogenous oligomer formation underlies DVL2 condensates and promotes Wnt/β-catenin signaling.

Activation of the Wnt/β-catenin pathway crucially depends on the polymerization of dishevelled 2 (DVL2) into biomolecular condensates. However, given the low affinity of known DVL2 self-interaction sites and its low cellular concentration, it is unclear how polymers can form. Here, we detect oligomeric DVL2 complexes at endogenous protein levels in human cell lines, using a biochemical ultracentrifugation assay. We identify a low-complexity region (LCR4) in the C-terminus whose deletion and fusion decreased and increased the complexes, respectively. Notably, LCR4-induced complexes correlated with the formation of microscopically visible multimeric condensates. Adjacent to LCR4, we mapped a conserved domain (CD2) promoting condensates only. Molecularly, LCR4 and CD2 mediated DVL2 self-interaction via aggregating residues and phenylalanine stickers, respectively. Point mutations inactivating these interaction sites impaired Wnt pathway activation by DVL2. Our study discovers DVL2 complexes with functional importance for Wnt/β-catenin signaling. Moreover, we provide evidence that DVL2 condensates form in two steps by pre-oligomerization via high-affinity interaction sites, such as LCR4, and subsequent condensation via low-affinity interaction sites, such as CD2.

Identifying colorectal cancer-specific vulnerabilities in the Wnt-driven long non-coding transcriptome

BackgroundAberrant Wnt pathway activation is a key driver of colorectal cancer (CRC) and is essential to sustain tumour growth and progression. Although the downstream protein-coding target genes of the Wnt...

NID1 promotes laryngeal cancer stemness via activating WNT pathway

BackgroundLaryngeal cancer (LCA) is one of the most common head and neck squamous cell carcinoma with poor outcome. LCA stem cells are the main reason for LCA therapy resistance and relapse. Understanding the molecular mechanisms of the self-renew of LCA stem cells is critical to develop now targets and strategies for LCA therapy.MethodsQ-PCR and western blotting assays were used to determine NID1 level in LCA tissues and normal laryngeal tissues. MTT, colony formation assay, apoptosis assay and animal model were used to investigate the effect of NID1 on radiotherapy resistance. Side population assay and sphere formation assay were used to determine the role of LCA in the self-renew of LCA stem cells.ResultsNID1 was upregulated in LCA tissues, particularly in LCA tissues derived from relapsed patients, and associated with had poor outcome. NID1 knockdown suppressed radiotherapy resistance and the self-renew of LCA stem cells, while NID1 overexpression promoted radiotherapy resistance and the self-renew of LCA stem cells. Further analysis showed that NID1 promotes radiotherapy resistance and the self-renew of LCA stem cells via activating WNT pathway. Moreover, NID1 level was positively correlated with nuclear β-Catenin level in LCA tissues.ConclusionOur results show that NID1 promotes radiotherapy resistance and the self-renew of LCA stem cells via activating WNT pathway, providing a novel potential target for LCA treatment.

Enhanced reno-protective effects of CHIR99021 modified mesenchymal stem cells against rat acute kidney injury model

Introduction: Mesenchymal stem cells of human umbilical cord origin (hucMSCs) appear to be an attractive candidate for cell-based therapies. However, their efficacy requires improvement as poor survival and specific homing to the site of injury are the major barriers to their effective implementation in cell therapy. As Wnt signaling pathway is involved in the development and repair of organs, we adopted a preconditioning strategy of stem cells by using CHIR99021 compound (a Wnt pathway agonist) to potentiate hucMSCs beneficial effects and circumvent their therapeutic limitations. Methods: We treated hucMSCs with 5 µM of CHIR99021 and evaluated the expression levels of genes involved in different biological processes through qRT-PCR. Subsequently, we examined the effectiveness of preconditioned cells (CHIR99021-hucMSCs) in a cisplatin-induced rat acute kidney injury model. Amelioration in tissue injury was evaluated by histopathology, immunohistochemistry and renal functional assessment. Results: In treated groups, we observed preserved renal tissue architecture in terms of lesser epithelial cells necrosis (P ≤ 0.001) and cast formation ( ≤ 0.05). Accelerated proliferation of injured tubular cells (P ≤ 0.001) and low serum creatinine values (P ≤ 0.01) were observed in preconditioned hucMSCs group compared to untreated AKI rats. In addition, administration of preconditioned hucMSCs in kidney injury model offered better restoration of tubular cell membrane β-catenin molecules. Our findings showed that CHIR99021-modified hucMSCs may exhibit better capacity for cell migration and proliferation. Conclusion: The results showed that preconditioning of stem cells with Wnt pathway activators could provide advanced benefits for organ repair, which may contribute to design a more effective therapeutic approach for renal regeneration.

Transcriptional profiles of murine oligodendrocyte precursor cells across the lifespan.

Oligodendrocyte progenitor cells (OPCs) are highly dynamic, widely distributed glial cells of the central nervous system (CNS) that are responsible for generating myelinating oligodendrocytes during development. By also generating new oligodendrocytes in the adult CNS, OPCs allow formation of new myelin sheaths in response to environmental and behavioral changes and play a crucial role in regenerating myelin following demyelination (remyelination). However, the rates of OPC proliferation and differentiation decline dramatically with aging, which may impair homeostasis, remyelination, and adaptive myelination during learning. To determine how aging influences OPCs, we generated a novel transgenic mouse line that expresses membrane-anchored EGFP under the endogenous promoter/enhancer of Matrilin-4 (Matn4-mEGFP) and performed high-throughput single-cell RNA sequencing, providing enhanced resolution of transcriptional changes during key transitions from quiescence to proliferation and differentiation across the lifespan. Comparative analysis of OPCs isolated from mice aged 30 to 720 days, revealed that aging induces distinct inflammatory transcriptomic changes in OPCs in different states, including enhanced activation of HIF-1α and Wnt pathways. Inhibition of these pathways in acutely isolated OPCs from aged animals restored their ability to differentiate, suggesting that this enhanced signaling may contribute to the decreased regenerative potential of OPCs with aging. This Matn4-mEGFP mouse line and single-cell mRNA datasets of cortical OPCs across ages help to define the molecular changes guiding their behavior in various physiological and pathological contexts.

A novel mutation in the BTB domain impairs transcriptional repression function of KCTD1 leading to syndromic microtia

Microtia is a common birth defect affecting the external ears and encompasses a spectrum of congenital anomalies of the auricle. For some of the microtia-associated syndromes, the additional abnormalities are not easily observed or with variable expressivity. Identifying pathogenic mutations through genetic testing is of great help in recognizing these highly heterogeneous syndromes in clinical practice. We reported a novel de novo KCTD1 mutation in a Chinese patient with congenital microtia. It expands the mutational spectrum of KCTD1 and provide an additional scalp-ear-nipple patient with typical and atypical clinical presentations. The identified mutation in the BTB domain impairs the suppressive activity of the AP-2 transcription factor family and may impact on maintaining the finely tuned activity of WNT pathway, which directs stem cell development in ectoderm patterning and craniofacial development. Due to the variable expressive clinical phenotypes of syndromic microtia, genetic molecular testing could be of great help in the definite diagnosis.

Reconstructing signaling history of single cells with imaging-based molecular recording.

The intensity and duration of biological signals encode information that allows a few pathways to regulate a wide array of cellular behaviors. Despite the central importance of signaling in biomedical research, our ability to quantify it in individual cells over time remains limited. Here, we introduce INSCRIBE, an approach for reconstructing signaling history in single cells using endpoint fluorescence images. By regulating a CRISPR base editor, INSCRIBE generates mutations in genomic target sequences, at a rate proportional to signaling activity. The number of edits is then recovered through a novel ratiometric readout strategy, from images of two fluorescence channels. We engineered human cell lines for recording WNT and BMP pathway activity, and demonstrated that INSCRIBE faithfully recovers both the intensity and duration of signaling. Further, we used INSCRIBE to study the variability of cellular response to WNT and BMP stimulation, and test whether the magnitude of response is a stable, heritable trait. We found a persistent memory in the BMP pathway. Progeny of cells with higher BMP response levels are likely to respond more strongly to a second BMP stimulation, up to 3 weeks later. Together, our results establish a scalable platform for genetic recording and in situ readout of signaling history in single cells, advancing quantitative analysis of cell-cell communication during development and disease.

Extraembryonic mesoderm cells derived from human embryonic stem cells rely on Wnt pathway activation.

Extraembryonic mesoderm cells (EXMCs) are involved in the development of multiple embryonic lineages and umbilical cord formation, where they subsequently develop into mesenchymal stem cells (MSCs). Although EXMCs can be generated from human naïve embryonic stem cells (ESCs), it is unclear whether human primed ESCs (hpESCs) can differentiate into EXMCs that subsequently produce MSCs. The present report described a three-dimensional differentiation protocol to induce hpESCs into EXMCs by activating the Wnt pathway using CHIR99021. Single-cell transcriptome and immunostaining analyses revealed that the EXMC characteristics were similar to those of post-implantation embryonic EXMCs. Cell sorting was used to purify and expand the EXMCs. Importantly, these EXMCs secreted extracellular matrix proteins, including COL3A1 and differentiated into MSCs. Inconsistent with other MSC types, these MSCs exhibited a strong differentiation potential for chondrogenic and osteogenic cells and lacked adipocyte differentiation. Together, these findings provided a protocol to generate EXMCs and subsequent MSCs from hpESCs.

The soluble factor milieu in idiopathic pulmonary fibrosis dysregulates epithelial differentiation.

In idiopathic pulmonary fibrosis (IPF), epithelial abnormalities are present including bronchiolization and alveolar cell dysfunction. We hypothesized that the IPF microenvironment disrupts normal epithelial growth and differentiation. We mimicked the soluble factors within an IPF microenvironment using an IPF cocktail (IPFc), composed of nine factors which are increased in IPF lungs (CCL2, IL-1β, IL-4, IL-8, IL-13, IL-33, TGF-β, TNFα, and TSLP). Using IPFc, we asked whether the soluble factor milieu in IPF affects epithelial growth and differentiation and how IPFc compares to TGF-β alone. Epithelial growth and differentiation were studied using mouse lung organoids (primary Epcam+ epithelial cells co-cultured with CCL206 fibroblasts). Organoids exposed to IPFc and TGF-β were re-sorted into epithelial and fibroblast fractions and subjected to RNA sequencing. IPFc did not affect the number of organoids formed. However, pro-surfactant protein C expression was decreased. On these parameters, TGF-β alone had similar effects. However, RNA sequencing of re-sorted organoids revealed that IPFc and TGF-β had distinct effects on both epithelial cells and fibroblasts. IPFc upregulated goblet cell markers, whereas these were inhibited by TGF-β. Although both IPFc and TGF-β increased extracellular matrix gene expression, only TGF-β increased myofibroblast markers. VEGF-C and Wnt signaling were among the most differentially regulated signaling pathways by IPFc versus TGF-β. Interestingly, Wnt pathway activation rescued Sftpc downregulation induced by IPFc. In conclusion, IPFc alters epithelial differentiation in a way that is distinct from TGF-β. Alterations in Wnt signaling contribute to these effects. IPFc may be a more comprehensive representation of the soluble factor microenvironment in IPF.

Stimulating Wnt signaling reveals context-dependent genetic effects on gene regulation in primary human neural progenitors.

Gene regulatory effects have been difficult to detect at many non-coding loci associated with brain-related traits, likely because some genetic variants have distinct functions in specific contexts. To explore context-dependent gene regulation, we measured chromatin accessibility and gene expression after activation of the canonical Wnt pathway in primary human neural progenitors (n = 82 donors). We found that TCF/LEF motifs and brain-structure-associated and neuropsychiatric-disorder-associated variants were enriched within Wnt-responsive regulatory elements. Genetically influenced regulatory elements were enriched in genomic regions under positive selection along the human lineage. Wnt pathway stimulation increased detection of genetically influenced regulatory elements/genes by 66%/53% and enabled identification of 397 regulatory elements primed to regulate gene expression. Stimulation also increased identification of shared genetic effects on molecular and complex brain traits by up to 70%, suggesting that genetic variant function during neurodevelopmental patterning can lead to differences in adult brain and behavioral traits.

Cuproptosis in microsatellite stable colon cancer cells affects the cytotoxicity of CD8+T through the WNT signaling pathway

The microsatellite stable (MSS) colon cancer (CC) has long been considered resistant to immunotherapy. Cuproptosis, as a novel form of cell death, may interact with tumor immunity. This project focused on the impact of cuproptosis on the cytotoxicity of CD8+T in MSS CC, aiming to provide effective clues for improving the treatment strategy of MSS CC. The study developed an MSS CC cuproptosis model using 50nM elesclomol and 1μM CuCl2. Cuproptotic SW480cells were directly co-cultured with CD8+ T cells. Cuproptosis levels were assessed via intracellular copper ion detection, Western blot, and confocal laser scanning microscopy. CCK-8, Hochest/PI staining, CFSE cell proliferation assay, LDH cytotoxicity detection, and ELISA were used to evaluate CD8+ T cell immune activity and cytotoxicity. Transcriptome sequencing and bioinformatics analysis identified regulated signals in cuproptotic SW480cells. A rescue experiment utilized a WNT pathway activator (BML-284). PD-L1 expression in cells/membranes was analyzed using qRT-PCR, Western blot, and flow cytometry. NSG mice were immunoreconstituted, and the effects of cuproptosis on immune infiltration and cancer progression in MSS CC mice were assessed using ELISA and immunohistochemistry (IHC). Treatment with 50nM elesclomol and 1μM CuCl2 significantly increased cuproptosis in SW480cells. Co-culture with CD8+ T cells enhanced their cytotoxicity. Sequencing revealed cuproptosis-mediated modulation of immune and inflammatory pathways, including WNT signaling. Rescue experiments showed downregulation of WNT signaling in cuproptotic SW480cells. Indirectly, CD8+ T cell immune function was enhanced by reducing PD-L1 expression. In mice, cuproptosis resulted in increased infiltration of CD8+ T cells in tumor tissue, leading to delayed cancer progression compared to the control group. Cuproptosis in MSS CC cells enhances the cytotoxicity of CD8+ T cells, which may be achieved through downregulation of the WNT signaling pathway and decreased expression of PD-L1. In the future, drugs that can induce cuproptosis may be a promising approach to improve MSS CC immunotherapy.

The overexpression of R-spondin 3 affects hair morphogenesis and hair development along with the formation and maturation of the hair follicle stem cells.

Mice hair follicles (HFs) are a valuable model for studying various aspects of hair biology, including morphogenesis, development, and regeneration due to their easily observable phenotype and genetic manipulability. The initiation and progression of hair follicle morphogenesis, as well as the hair follicle cycle, are regulated by various signaling pathways, of which the main role is played by the Wingless-type MMTV integration site family (Wnt) and the Bone Morphogenic Protein (BMP). During the hair follicle cycle, the BMP pathway maintains hair follicle stem cells (HFSCs) in a dormant state while the Wnt pathway activates them for hair growth. Given the pivotal role of the Wnt pathway in hair biology and HFSCs regulation, we investigated the influence of the Wnt modulator - R-spondin 3 (Rspo3), in these processes. For this purpose, we developed a transgenic mice model with the overexpression of Rspo3 (Rspo3GOF) in the whole ectoderm and its derivatives, starting from early morphogenesis. Rspo3GOF mice exhibited a distinct phenotype with sparse hair and visible bald areas, caused by reduced proliferation and increased apoptosis of hair matrix progenitor cells, which resulted in a premature anagen-to-catagen transition with a shortened growth phase and decreased overall length of all hair types. In addition, Rspo3GOF promoted induction of auchene and awl, canonical Wnt-dependent hair type during morphogenesis, but the overall hair amount remained reduced. We also discovered a delay in the pre-bulge formation during morphogenesis and prolonged immaturity of the HFSC population in the bulge region postnatally, which further impaired proper hair regeneration throughout the mice's lifespan. Our data supported that Rspo3 function observed in our model works in HFSCs' formation of pre-bulge during morphogenesis via enhancing activation of the canonical Wnt pathway, whereas in contrast, in the postnatal immature bulge, activation of canonical Wnt signaling was attenuated. In vitro studies on keratinocytes revealed changes in proliferation, migration, and colony formation, highlighting the inhibitory effect of constitutive overexpression of Rspo3 on these cellular processes. Our research provides novel insights into the role of Rspo3 in the regulation of hair morphogenesis and development, along with the formation and maturation of the HFSCs, which affect hair regeneration.

Cadherin adhesion complexes direct cell aggregation in the epithelial transition of Wnt-induced nephron progenitor cells.

In the developing mammalian kidney, nephron formation is initiated by a subset of nephron progenitor cells (NPCs). Wnt input activates a β-catenin (Ctnnb1)-driven, transcriptional nephrogenic program and the mesenchymal to epithelial transition (MET) of NPCs. Using an in vitro mouse NPC culture model, we observed that activation of the Wnt pathway results in the aggregation of induced NPCs, which is an initiating step in the MET program. Genetic removal showed aggregation was dependent on β-catenin. Modulating extracellular Ca2+ levels showed cell-cell contacts were Ca2+ dependent, suggesting a role for cadherin (Cdh)-directed cell adhesion. Molecular analysis identified Cdh2, Cdh4 and Cdh11 in NPCs, and the β-catenin directed upregulation of Cdh3 and Cdh4 accompanying the MET of induced NPCs. Mutational analysis of β-catenin supported a role for a Lef/Tcf-β-catenin-mediated transcriptional response in the cell aggregation process. Genetic removal of all four cadherins, and independent removal of α-catenin or of β-catenin-α-catenin interactions, abolished aggregation, but not the inductive response to Wnt pathway activation. These findings, and data in an accompanying article highlight the role of β-catenin in linking transcriptional programs to the morphogenesis of NPCs in mammalian nephrogenesis.