A mechanism of action-reflective, dual cell-based bioassay for determining the bioactivity of sclerostin-neutralizing antibodies.

Osteoporosis is a major threat to the elderly worldwide. The Wnt signaling pathway plays a critical role in bone development and homeostasis. Sclerostin, a Wnt ligand inhibitor, competes with Wnt ligands for low-density lipoprotein receptor-related protein 5 or 6 (LRP5/6) on osteoblasts, thereby suppressing bone formation. Sclerostin-neutralizing monoclonal antibodies (mAbs) have emerged as a potential bone-forming therapy for osteoporosis. A cell-based bioassay which determines the relative activity of a product, related to its mechanism of action, is of great importance from drug discovery to quality control and batch release. Currently used cell-based bioassays for sclerostin-neutralizing mAbs usually use Wnt1 or Wnt3a to stimulate the Wnt pathway; sclerostin is a direct inhibitor of Wnt1 but not Wnt3a. Wnt1 is a highly hydrophobic protein that binds to the producing cell membrane and acts in a juxtacrine manner to stimulate the Wnt pathway in neighboring cells. Bioassays for drugs that induce Wnt1 signaling should be performed in a juxtacrine manner. Here, we present a mechanism of action-reflective, dual cell-based reporter gene assay. In this assay, Wnt1 producer cells are co-cultured with cells containing the Wnt reporter genes, Wnt1 on the producer cells activates the Wnt signaling pathway in the reporter cells that are in direct cell-to-cell contact, and sclerostin-neutralizing mAbs specifically and effectively antagonize the sclerostin-mediated Wnt reporter gene suppression. This bioassay demonstrates good specificity, accuracy, linearity, and precision and is suitable for quality control, stability testing, batch release, and biosimilarity assessment of sclerostin-neutralizing mAbs.

WNT1/ROR2 pathway enhances the Triple-Negative breast cancer invasion, migration, and Epithelial-Mesenchymal transition.

It has been evidenced that ROR2 influences the growth of many tumors, including non-small cell lung cancer, osteosarcoma, and breast cancer. This research examined the effect of the WNT1/ROR2 signaling pathway on the progression of triple-negative breast cancer (TNBC). Bioinformatics analysis results demonstrated that ROR2 had a higher messenger RNA (mRNA) expression level in TNBC tissues and was positively correlated with poor patient prognosis. Western blot analysis (WB) and quantitative reverse transcription polymerase chain reaction demonstrated that TNBC cells had relatively higher ROR2 mRNA and protein levels than normal cell lines. Transwell and Cell Counting Kit-8 (CCK-8) assay further proved that downregulating ROR2 expression dramatically slowed the MDA-MB-231 cell progression. WB detection of epithelial-mesenchymal transition (EMT)-related proteins suggested that knocking down ROR2 could alleviate the EMT tendency of cancer cells. The WNT1/ROR2 signaling pathway could be inhibited by the WNT inhibitor pyrvinium pamoate (PP). Experiments on in vitro cell functional recovery have demonstrated that PP could restore malignant phenotypes caused by ROR2 overexpression. Finally, the mouse model experiments further validated the anticancer effect of PP on TNBC. Generally speaking, the malignant progression of TNBC could be stimulated by the WNT1/ROR2 signaling pathway which can be inhibited by PP, suggesting the potential value of PP in controlling TNBC.

The antifibrotic potential of IMT504: modulation of GLAST + Wnt1 + bone marrow stromal progenitors and hepatic microenvironment.

BACKGROUND: The immunomodulatory oligodeoxynucleotide (ODN) IMT504 might harbor antifibrotic properties within the liver. METHODS: Fibrosis models were induced in mice through thioacetamide (TAA) administration and bile-duct ligation. Cre-loxP mice were utilized to identify GLAST + Wnt1 + bone marrow stromal progenitors (BMSPs) and to examine their contribution with cells in the liver. In vivo and in vitro assays; flow-cytometry, immunohistochemistry, and qPCR were conducted. RESULTS: IMT504 demonstrated significant inhibition of liver fibrogenesis progression and reversal of established fibrosis. Early responses to IMT504 involved the suppression of profibrogenic and proinflammatory markers, coupled with an augmentation of hepatocyte proliferation. Additionally, this ODN stimulated the proliferation and mobilization of GLAST + Wnt1 + BMSPs, likely amplifying their contribution with endothelial- and hepatocytes-like cells. Moreover, IMT504 significantly modulated the expression levels of Wnt ligands and signaling pathway/target genes specifically within GLAST + Wnt1 + BMSPs, with minimal impact on other BMSPs. Intriguingly, both IMT504 and conditioned media from IMT504-pre-treated GLAST + Wnt1 + BMSPs shifted the phenotype of fibrotic macrophages, hepatic stellate cells, and hepatocytes, consistent with the potent antifibrotic effects observed. CONCLUSION: In summary, our findings identify IMT504 as a promising candidate molecule with potent antifibrotic properties, operating through both direct and indirect mechanisms, including the activation of GLAST + Wnt1 + BMSPs.

Dissociation of Drosophila Evi-Wg Complex Occurs Post Apical Internalization in the Maturing Acidic Endosomes.

Signaling pathways activated by secreted Wnt ligands play an essential role in tissue development and the progression of diseases, like cancer. Secretion of the lipid-modified Wnt proteins is tightly regulated by a repertoire of intracellular factors. For instance, a membrane protein, Evi, interacts with the Wnt ligand in the ER, and it is essential for its further trafficking and release in the extracellular space. After dissociating from the Wnt, the Wnt-unbound Evi is recycled back to the ER via Golgi. However, where in this trafficking path Wnt proteins dissociate from Evi remains unclear. Here, we have used the Drosophila wing epithelium to trace the route of the Evi-Wg (Wnt homolog) complex leading up to their separation. In these polarized cells, Wg is first trafficked to the apical surface; however, the secretion of Wg is believed to occurs post-internalization via recycling. Our results show that the Evi-Wg complex is internalized from the apical surface and transported to the retromer-positive endosomes. Furthermore, using antibodies that specifically label the Wnt-unbound Evi, we show that Evi and Wg separation occurs post-internalization in the acidic endosomes. These results refine our understanding of the polarized trafficking of Wg and highlight the importance of Wg endocytosis in its secondary secretion.

Effects of soluble Klotho and Wnt/ß-catenin signaling pathway in vascular calcification in chronic kidney disease model rats and the intervention of Shenyuan granules.

OBJECTIVE: This study aimed to investigate the effect of the soluble Klotho (sKlotho)/Wnt/ß-catenin signaling pathway on vascular calcification in rat models of chronic kidney disease (CKD) and the intervention effect of Shenyuan granules. METHODS: Rats with 5/6 nephrectomy and high phosphorus feeding were used to establish the vascular calcification model. The rats were given gradient doses of Shenyuan granules aqueous solution and calcitriol solution by gavage for 8 weeks, which were divided into experimental group and positive control group. RESULTS: The 5/6 nephrectomy combined with high phosphorus feeding induced thoracic aortic calcification in rats. Shenyuan granules intervention increased the serum sKlotho level, inhibited the mRNA and protein expression of Wnt1, ß-catenin, and Runx2 in the thoracic aorta, and alleviated thoracic aortic media calcification in rats. CONCLUSION: Shenyuan granules may partially regulate the Wnt/ß-catenin signaling pathway via serum sKl to interfere with the expression of Runx2, thereby improving vascular calcification in CKD.

High sugar diet promotes tumor progression paradoxically through aberrant upregulation of pepck1.

High dietary sugar (HDS), a contemporary dietary concern due to excessive intake of added sugars and carbohydrates, escalates the risk of metabolic disorders and concomitant cancers. However, the molecular mechanisms underlying HDS-induced cancer progression are not completely understood. We found that phosphoenolpyruvate carboxykinase 1 (PEPCK1), a pivotal enzyme in gluconeogenesis, is paradoxically upregulated in tumors by HDS, but not by normal dietary sugar (NDS), during tumor progression. Targeted knockdown of pepck1, but not pepck2, specifically in tumor tissue in Drosophila in vivo, not only attenuates HDS-induced tumor growth but also significantly improves the survival of Ras/Src tumor-bearing animals fed HDS. Interestingly, HP1a-mediated heterochromatin interacts directly with the pepck1 gene and downregulates pepck1 gene expression in wild-type Drosophila. Mechanistically, we demonstrated that, under HDS conditions, pepck1 knockdown reduces both wingless and TOR signaling, decreases evasion of apoptosis, reduces genome instability, and suppresses glucose uptake and trehalose levels in tumor cells in vivo. Moreover, rational pharmacological inhibition of PEPCK1, using hydrazinium sulfate, greatly improves the survival of tumor-bearing animals with pepck1 knockdown under HDS. This study is the first to show that elevated levels of dietary sugar induce aberrant upregulation of PEPCK1, which promotes tumor progression through altered cell signaling, evasion of apoptosis, genome instability, and reprogramming of carbohydrate metabolism. These findings contribute to our understanding of the complex relationship between diet and cancer at the molecular, cellular, and organismal levels and reveal PEPCK1 as a potential target for the prevention and treatment of cancers associated with metabolic disorders.

Ropivacaine Administration Suppressed A549 Lung Adenocarcinoma Cell Proliferation and Migration via ACE2 Upregulation and Inhibition of the Wnt1 Pathway.

BACKGROUND: Previous studies have suggested that perioperative anesthesia could have direct impacts on cancer cell biology. The present study investigated the effects of ropivacaine administration on lung adenocarcinoma cells. METHODS: Ropivacaine was administered to A549 cells at concentrations of 0.1, 1, and 6 mM for 2 h. Angiotensin-converting enzyme 2 (ACE2) small interfering RNA (siRNA) transfection was performed 6 h prior to ropivacaine administration. Cell proliferation and migration were assessed with cell counting kit 8 (CCK-8) and a wound healing assay at 0 and 24 h after anesthesia exposure. PCR arrays were performed, followed by PCR validation. RESULTS: Ropivacaine administration inhibited A549 cell proliferation and migration in a concentration-dependent manner, with ACE2 upregulation and HIF1α (hypoxia-inducible factor 1α) downregulation. The anticancer effect of ropivacaine was canceled out via ACE2 siRNA transfection. PCR arrays showed specific gene change patterns in the ropivacaine and respective ACE2-knockdown groups. EGFR (epidermal growth factor receptor), BAX (Bcl-2-associated X protein) and BCL2 (B-cell/CLL lymphoma 2) were suppressed with ropivacaine administration; these effects were reversed via ACE2 siRNA induction. CONCLUSION: Ropivacaine administration inhibited A549 cell biology in conjunction with ACE2 upregulation via the inhibition of the Wnt1 (wingless/Integrated 1) pathway.

Control of fate specification within the dorsal head of Drosophila melanogaster.

During development, unique combinations of transcription factors and signaling pathways carve the nascent eye-antennal disc of the fruit fly Drosophila melanogaster into several territories that will eventually develop into the compound eye, ocelli, head epidermis, bristles, antenna and maxillary palpus of the adult head. Juxtaposed patterns of Hedgehog (Hh) and Decapentaplegic (Dpp) initiate compound eye development, while reciprocal domains of Dpp and Wingless (Wg) induce formation of the antennal and maxillary palp fields. Hh and Wg signaling, but not Dpp, contribute to the patterning of the dorsal head vertex. Here, we show that combinatorial reductions of the Pax6 transcription factor Twin of Eyeless and either the Wg pathway or the Mirror (Mirr) transcription factor trigger a transformation of the ocelli into a compound eye and the neighboring head epidermis into an antenna. These changes in fate are accompanied by the ectopic expression of Dpp, which might be expected to trigger these changes in fate. However, the transformation of the field cannot be replicated by increasing Dpp levels alone despite the recreation of adjacent Hh-Dpp and Wg-Dpp domains. As such, the emergence of these ectopic organs occurs through a unique regulatory path.

Assessing the contribution of genes involved in monogenic bone disorders to the etiology of atypical femoral fractures.

BACKGROUND: Recent studies suggested that genetic variants associated with monogenic bone disorders were involved in the pathogenesis of atypical femoral fractures (AFF). Here, we aim to identify rare genetic variants by whole exome sequencing in genes involved in monogenic rare skeletal diseases in 12 women with AFF and 4 controls without any fracture. RESULTS: Out of 33 genetic variants identified in women with AFF, eleven (33.3%) were found in genes belonging to the Wnt pathway (LRP5, LRP6, DAAM2, WNT1, and WNT3A). One of them was rated as pathogenic (p.Pro582His in DAAM2), while all others were rated as variants of uncertain significance according to ClinVar and ACMG criteria. CONCLUSIONS: Osteoporosis, rare bone diseases, and AFFs may share the same genes, thus making it even more difficult to identify unique risk factors.

Multi-omics analyses reveal aberrant differentiation trajectory with WNT1 loss-of-function in type XV osteogenesis imperfecta.

Osteogenesis imperfecta (OI) is a group of severe genetic bone disorders characterized by congenital low bone mass, deformity, and frequent fractures. Type XV OI is a moderate to severe form of skeletal dysplasia caused by WNT1 variants. In this cohort study from southern China, we summarized the clinical phenotypes of patients with WNT1 variants and found that the proportion of type XV patients was around 10.3% (25 out of 243) with a diverse spectrum of phenotypes. Functional assays indicated that variants of WNT1 significantly impaired its secretion and effective activity, leading to moderate to severe clinical manifestations, porous bone structure, and enhanced osteoclastic activities. Analysis of proteomic data from human skeleton indicated that the expression of SOST (sclerostin) was dramatically reduced in type XV patients compared to patients with COL1A1 quantitative variants. Single-cell transcriptome data generated from human tibia samples of patients diagnosed with type XV OI and leg-length discrepancy, respectively, revealed aberrant differentiation trajectories of skeletal progenitors and impaired maturation of osteocytes with loss of WNT1, resulting in excessive CXCL12+ progenitors, fewer mature osteocytes, and the existence of abnormal cell populations with adipogenic characteristics. The integration of multi-omics data from human skeleton delineates how WNT1 regulates the differentiation and maturation of skeletal progenitors, which will provide a new direction for the treatment strategy of type XV OI and relative low bone mass diseases such as early onset osteoporosis.

Osteogenesis imperfecta is a rare disease characterized by low bone mass, frequent fractures, and long bone deformity. Type XV osteogenesis imperfect is an autosomal recessive disorder caused by WNT1 variants, while heterozygous variants of WNT1 result in early onset osteoporosis. In this cohort study, we summarized the clinical features of 25 patients diagnosed with type XV osteogenesis imperfect. The WNT1 variants were confirmed by genetic test. Molecular assays were conducted to reveal the impact of variants on WNT1 protein activity and bone structure. We then compared the protein levels in bone tissues isolated from the type XV patients and patients with mild deformity using proteomic method, and found that the expression of SOST, mainly produced by mature osteoblasts and osteocytes, was dramatically reduced in type XV patients. We further compared the global mRNA expression levels in the skeletal cells using single-cell RNA sequencing. Analyses of these data indicated that more immature progenitors were identified and maturation of osteocytes was impaired with WNT1 loss-of-function. Our study helps to understand the underlying pathogenesis of type XV osteogenesis imperfecta.

Wnt1 gene expression in the heart left ventricle as a response to the various durations of the intensive exercise: An experimental study.

Objective. Myocardial fibrosis is a devastating condition causing millions of deaths yearly. Several factors, such as aging, cause myocardial fibrosis. The Wnt/ß-catenin pathway is one of the critical intracellular signaling for the development of cardiac fibrosis. Molecular and cellular mechanism of myocardial fibrosis induced by intensive exercise is not well-understood. The current study evaluates the effects of short- and long-term intensive exercise on the Wnt1 gene expression in a heart left ventricle in an animal model. Methods. Twenty-one male Wistar rats (mean weight 250±50 g) were divided into three groups (n=7): 1) control group (C); 2) short-term regular intensive exercise group (S-RIE, high-intensity exercise for one month six days weekly for 60 min with speed of 35 m/min), and 3) long-term regular intensive exercise group (L-RIE, high-intensity exercise for six months six days daily for 60 min with speed of 35 m/min). The heart left ventricle was isolated at the end of the experiment, and the relative gene expression of the Wnt1 gene was measured by the Real-Time PCR. Results. The L-RIE group showed a significant increase in the Wnt1 expression compared to the S-RIE and the control group. Although no difference was observed in the Wnt1 mRNA level in the S-RIE group compared to the control group, Wnt1 mRNA level increased in the L-RIE group compared to the S-RIE group. Conclusion. The exercise duration was of a great importance in the Wnt1 gene expression. Regular intensive exercise may be involved in the formation of the myocardial fibrosis by increasing the expression of the Wnt1 gene.

Wnt/Wingless signaling promotes lipid mobilization through signal-induced transcriptional repression.

The Wnt/Wingless signaling pathway plays critical roles in metazoan development and energy metabolism, but its role in regulating lipid homeostasis remains not fully understood. Here, we report that the activation of canonical Wnt/Wg signaling promotes lipolysis while concurrently inhibiting lipogenesis and fatty acid ß-oxidation in both larval and adult adipocytes, as well as cultured S2R+ cells, in Drosophila. Using RNA-sequencing and CUT&RUN (Cleavage Under Targets & Release Using Nuclease) assays, we identified a set of Wnt target genes responsible for intracellular lipid homeostasis. Notably, active Wnt signaling directly represses the transcription of these genes, resulting in decreased de novo lipogenesis and fatty acid ß-oxidation, but increased lipolysis. These changes lead to elevated free fatty acids and reduced triglyceride (TG) accumulation in adipocytes with active Wnt signaling. Conversely, downregulation of Wnt signaling in the fat body promotes TG accumulation in both larval and adult adipocytes. The attenuation of Wnt signaling also increases the expression of specific lipid metabolism-related genes in larval adipocytes, wing discs, and adult intestines. Taken together, these findings suggest that Wnt signaling-induced transcriptional repression plays an important role in regulating lipid homeostasis by enhancing lipolysis while simultaneously suppressing lipogenesis and fatty acid ß-oxidation.

The role of miR-128 and MDFI in cardiac hypertrophy and heart failure: Mechanistic.

Heart failure (HF) prognosis depends on various regulatory factors; microRNA-128 (miR-128) is identified as a regulator of cardiac fibrosis, contributing to HF. MyoD family inhibitor (MDFI), which is reported to be related with Wnt/ß-catenin pathway, is supposed to be regulated by miR-128. This study investigates the interaction between miR-128 and MDFI in cardiomyocyte development and elucidates its role in heart injury. Gene expression profiling assessed miR-128's effect on MDFI expression in HF using qPCR and Western blot analysis. Luciferase assays studied the direct interaction between miR-128 and MDFI. MTT, transwell, and immunohistochemistry evaluated the effects of miR-128 and MDFI on myocardial cells in mice HF. Genescan and luciferase assays validated the interaction between miR-128 and MDFI sequences. miR-128 mimics significantly reduced MDFI expression at mRNA and protein levels with decrease rate of 55%. Overexpression of miR-128 promoted apoptosis with the increase rate 65% and attenuated cardiomyocyte proliferation, while MDFI upregulation significantly enhanced proliferation. Elevated miR-128 levels upregulated Wnt1 and ß-catenin expression, whereas increased MDFI levels inhibited these expressions. Histological analysis with haematoxylin and eosin staining revealed that miR-128 absorption reduced MDFI expression, hindering cell proliferation and cardiac repair, with echocardiography showing corresponding improvements in cardiac function. Our findings suggest miR-128 interacts with MDFI, playing a crucial role in HF management by modulating the Wnt1/ß-catenin pathway. Suppression of miR-128 could promote cardiomyocyte proliferation, highlighting the potential value of the miR-128/MDFI interplay in HF treatment.

Excess Dally-like Induces Malformation of Drosophila Legs.

Glypicans are closely associated with organ development and tumorigenesis in animals. Dally-like (Dlp), a membrane-bound glypican, plays pivotal roles in various biological processes in Drosophila. In this study, we observed that an excess of Dlp led to the malformation of legs, particularly affecting the distal part. Accordingly, the leg disc was shrunken and frequently exhibited aberrant morphology. In addition, elevated Dlp levels induced ectopic cell death with no apparent cell proliferation changes. Furthermore, Dlp overexpression in the posterior compartment significantly altered Wingless (Wg) distribution. We observed a marked expansion of Wg distribution within the posterior compartment, accompanied by a corresponding decrease in the anterior compartment. It appears that excess Dlp guides Wg to diffuse to cells with higher Dlp levels. In addition, the distal-less (dll) gene, which is crucial for leg patterning, was up-regulated significantly. Notably, dachshund (dac) and homothorax (hth) expression, also essential for leg patterning and development, only appeared to be negligibly affected. Based on these findings, we speculate that excess Dlp may contribute to malformations of the distal leg region of Drosophila, possibly through its influence on Wg distribution, dll expression and induced cell death. Our research advances the understanding of Dlp function in Drosophila leg development.

Wnt signaling modulates the response to DNA damage in the Drosophila wing imaginal disc by regulating the EGFR pathway.

Despite the deep conservation of the DNA damage response (DDR) pathway, cells in different contexts vary widely in their susceptibility to DNA damage and their propensity to undergo apoptosis as a result of genomic lesions. One of the cell signaling pathways implicated in modulating the DDR is the highly conserved Wnt pathway, which is known to promote resistance to DNA damage caused by ionizing radiation in a variety of human cancers. However, the mechanisms linking Wnt signal transduction to the DDR remain unclear. Here, we use a genetically encoded system in Drosophila to reliably induce consistent levels of DNA damage in vivo, and demonstrate that canonical Wnt signaling in the wing imaginal disc buffers cells against apoptosis in the face of DNA double-strand breaks. We show that Wg, the primary Wnt ligand in Drosophila, activates epidermal growth factor receptor (EGFR) signaling via the ligand-processing protease Rhomboid, which, in turn, modulates the DDR in a Chk2-, p53-, and E2F1-dependent manner. These studies provide mechanistic insight into the modulation of the DDR by the Wnt and EGFR pathways in vivo in a highly proliferative tissue. Furthermore, they reveal how the growth and patterning functions of Wnt signaling are coupled with prosurvival, antiapoptotic activities, thereby facilitating developmental robustness in the face of genomic damage.

Heterogeneity of Wnt1-Cre-marked and Pax2-Cre-marked first branchial arch cranial neural crest cells in mice.

OBJECTIVES: This study aimed to explore the heterogeneity and gene ontology of Wnt1-Cre-marked and Pax2-Cre-marked first branchial arch cranial neural crest cells (CNCs) in mice. METHODS: The embryos of Wnt1-Cre;R26RmTmG and Pax2-Cre;R26RmTmG at embryonic day (E)8.0-E9.25 were collected for histological observation. We performed immunostaining to compare green fluorescent protein (GFP)-positive CNCs in Pax2-Cre;R26RAi9 and Wnt1-Cre;R26RAi9 mice at E15.5. Single-cell RNA sequencing (scRNA-seq) was used to analyze the first branchial arch GFP-positive CNCs from Wnt1-Cre;R26RmTmG and Pax2-cre;R26RmTmGmice at E10.5. Real time fluorescence quantitative polymerase chain reaction (q-PCR) was performed to validate the differential genes. RESULTS: Wnt1-Cre-marked and Pax2-Cre-marked CNCs migrated from the neural plateto first and second branchial arches and to the first branchial arch, respectively, at E8.0. Although Wnt1-Cre-marked and Pax2-Cre-marked CNCs were found mostly in cranial-facial tissues, the former had higher expression in palate and tongue. The results of scRNA-seq showed that Pax2-Cre-marked CNCs specifically contributed to osteoblast differentiation and ossification, while Wnt1-Cre-marked CNCs participated in limb development, cell migration, and ossification. The q-PCR data also confirmed the results of gene ontology analysis. CONCLUSIONS: Pax2-Cre mice are perfect experimental animal models for research on first branchial arch CNCs and derivatives in osteoblast differentiation and ossification.

Evaluation of the Canonical Wnt Signaling Pathway in the Hearts of Hypertensive Rats of Various Etiologies.

Wnt/ß-catenin signaling dysregulation is associated with the pathogenesis of many human diseases, including hypertension and heart disease. The aim of this study was to immunohistochemically evaluate and compare the expression of the Fzd8, WNT1, GSK-3ß, and ß-catenin genes in the hearts of rats with spontaneous hypertension (SHRs) and deoxycorticosterone acetate (DOCA)-salt-induced hypertension. The myocardial expression of Fzd8, WNT1, GSK-3ß, and ß-catenin was detected by immunohistochemistry, and the gene expression was assessed with a real-time PCR method. In SHRs, the immunoreactivity of Fzd8, WNT1, GSK-3ß, and ß-catenin was attenuated in comparison to that in normotensive animals. In DOCA-salt-induced hypertension, the immunoreactivity of Fzd8, WNT1, GSK-3ß, and ß-catenin was enhanced. In SHRs, decreases in the expression of the genes encoding Fzd8, WNT1, GSK-3ß, and ß-catenin were observed compared to the control group. Increased expression of the genes encoding Fzd8, WNT1, GSK-3ß, and ß-catenin was demonstrated in the hearts of rats with DOCA-salt-induced hypertension. Wnt signaling may play an essential role in the pathogenesis of arterial hypertension and the accompanying heart damage. The obtained results may constitute the basis for further research aimed at better understanding the role of the Wnt/ß-catenin pathway in the functioning of the heart.

E3 ubiquitin ligase Deltex facilitates the expansion of Wingless gradient and antagonizes Wingless signaling through a conserved mechanism of transcriptional effector Armadillo/ß-catenin degradation.

The Wnt/Wg pathway controls myriads of biological phenomena throughout the development and adult life of all organisms across the phyla. Thus, an aberrant Wnt signaling is associated with a wide range of pathologies in humans. Tight regulation of Wnt/Wg signaling is required to maintain proper cellular homeostasis. Here, we report a novel role of E3 ubiquitin ligase Deltex in Wg signaling regulation. Drosophila dx genetically interacts with wg and its pathway components. Furthermore, Dx LOF results in a reduced spreading of Wg while its over-expression expands the diffusion gradient of the morphogen. We attribute this change in Wg gradient to the endocytosis of Wg through Dx which directly affects the short- and long-range Wg targets. We also demonstrate the role of Dx in regulating Wg effector Armadillo where Dx down-regulates Arm through proteasomal degradation. We also showed the conservation of Dx function in the mammalian system where DTX1 is shown to bind with ß-catenin and facilitates its proteolytic degradation, spotlighting a novel step that potentially modulates Wnt/Wg signaling cascade.

Wg/Wnt-signaling-induced nuclear translocation of ß-catenin is attenuated by a ß-catenin peptide through its interference with the IFT-A complex.

Wnt/Wingless (Wg) signaling is critical in development and disease, including cancer. Canonical Wnt signaling is mediated by ß-catenin/Armadillo (Arm in Drosophila) transducing signals to the nucleus, with IFT-A/Kinesin 2 complexes promoting nuclear translocation of ß-catenin/Arm. Here, we demonstrate that a conserved small N-terminal Arm34-87/ß-catenin peptide binds to IFT140, acting as a dominant interference tool to attenuate Wg/Wnt signaling in vivo. Arm34-87 expression antagonizes endogenous Wnt/Wg signaling, resulting in the reduction of its target expression. Arm34-87 inhibits Wg/Wnt signaling by interfering with nuclear translocation of endogenous Arm/ß-catenin, and this can be modulated by levels of wild-type ß-catenin or IFT140, with the Arm34-87 effect being enhanced or suppressed. Importantly, this mechanism is conserved in mammals with the equivalent ß-catenin24-79 peptide blocking nuclear translocation and pathway activation, including in cancer cells. Our work indicates that Wnt signaling can be regulated by a defined N-terminal ß-catenin peptide and thus might serve as an entry point for therapeutic applications to attenuate Wnt/ß-catenin signaling.

The Oct4-related PouV gene, pou5f3, mediates isthmus development in zebrafish by directly and dynamically regulating pax2a.

Using a transgenic zebrafish line harboring a heat-inducible dominant-interference pou5f3 gene (en-pou5f3), we reported that this PouV gene is involved in isthmus development at the midbrain-hindbrain boundary (MHB), which patterns the midbrain and cerebellum. Importantly, the functions of pou5f3 reportedly differ before and after the end of gastrulation. In the present study, we examined in detail the effects of en-pou5f3 induction on isthmus development during embryogenesis. When en-pou5f3 was induced around the end of gastrulation (bud stage), the isthmus was abrogated or deformed by the end of somitogenesis (24 hours post-fertilization). At this stage, the expression of MHB markers -- such as pax2a, fgf8a, wnt1, and gbx2 -- was absent in embryos lacking the isthmus structure, whereas it was present, although severely distorted, in embryos with a deformed isthmus. We further found that, after en-pou5f3 induction at late gastrulation, pax2a, fgf8a, and wnt1 were immediately and irreversibly downregulated, whereas the expression of en2a and gbx2 was reduced only weakly and slowly. Induction of en-pou5f3 at early somite stages also immediately downregulated MHB genes, particularly pax2a, but their expression was restored later. Overall, the data suggested that pou5f3 directly upregulates at least pax2a and possibly fgf8a and wnt1, which function in parallel in establishing the MHB, and that the role of pou5f3 dynamically changes around the end of gastrulation. We next examined the transcriptional regulation of pax2a using both in vitro and in vivo reporter analyses; the results showed that two upstream 1.0-kb regions with sequences conserved among vertebrates specifically drove transcription at the MHB. These reporter analyses confirmed that development of the isthmic organizer is regulated by PouV through direct regulation of pax2/pax2a in vertebrate embryos.