Low-density lipoprotein receptor-related protein-5 binds to Axin and regulates the canonical Wnt signaling pathway

Regulation of SUMOylation Targets Associated With Wnt/β-Catenin Pathway

Wnt/β-catenin signaling is a delicate and complex signal transduction pathway mediated by multiple signaling molecules, which plays a significant role in regulating human physiology and pathology. Abnormally activated Wnt/β-catenin signaling pathway plays a crucial role in promoting malignant tumor occurrence, development, recurrence, and metastasis, particularly in cancer stem cells. Studies have shown that the Wnt/β-catenin signaling pathway controls cell fate and function through the transcriptional and post-translational regulation of omics networks. Therefore, precise regulation of Wnt/β-catenin signaling as a cancer-targeting strategy may contribute to the treatment of some malignancies. SUMOylation is a post-translational modification of proteins that has been found to play a major role in the Wnt/β-catenin signaling pathway. Here, we review the complex regulation of Wnt/β-catenin signaling by SUMOylation and discuss the potential targets of SUMOylation therapy.

Ciliary membrane, localised lipid modification and cilia function

Cilium, a tiny microtubule-based cellular appendage critical for cell signalling and physiology, displays a large variety of receptors. The composition and turnover of ciliary lipids and receptors determine cell behaviour. Due to the exclusion of ribosomal machinery and limited membrane area, a cilium needs adaptive logistics to actively reconstitute the lipid and receptor compositions during development and differentiation. How is this dynamicity generated? Here, we examine whether, along with the Intraflagellar-Transport, targeted changes in sector-wise lipid composition could control the receptor localisation and functions in the cilia. We discuss how an interplay between ciliary lipid composition, localised lipid modification, and receptor function could contribute to cilia growth and signalling. We argue that lipid modification at the cell-cilium interface could generate an added thrust for a selective exchange of membrane lipids and the transmembrane and membrane-associated proteins.

Molecular Mechanisms of Isolated Polycystic Liver Diseases

Polycystic liver disease (PLD) is a rare autosomal dominant disorder including two genetically and clinically distinct forms: autosomal dominant polycystic kidney disease (ADPKD) and isolated polycystic liver disease (PCLD). The main manifestation of ADPKD is kidney cysts, while PCLD has predominantly liver presentations with mild or absent kidney cysts. Over the past decade, PRKCSH, SEC63, ALG8, and LRP5 have been candidate genes of PCLD. Recently, more candidate genes such as GANAB, SEC61B, and ALR9 were also reported in PCLD patients. This review focused on all candidate genes of PCLD, including the newly established novel candidate genes. In addition, we also discussed some other genes which might also contribute to the disease.

Heterozygote loss-of-function variants in the LRP5 gene cause familial exudative vitreoretinopathy

BACKGROUND

Familial exudative vitreoretinopathy (FEVR) is an inherited ocular disease with clinical manifestations of aberrant retinal vasculature. We aimed to identify novel causative variants responsible for FEVR and provided evidence for the genetic counselling of FEVR.

METHODS

We applied whole-exome sequencing (WES) on the genomic DNA samples from the probands and performed Sanger sequencing for variant validation. Western blot analysis and luciferase assays were performed to test the expression levels and the activity of mutant proteins.

RESULTS

We identified one novel heterozygous nonsense variant, and three novel heterozygous frameshift variants including c.1801G>T (p.G601*), c.1965delC (p.H656Tfs*41), c.4445delC (p.S1482Cfs*17), and c.4482delC (p.P1495Rfs*4), which disabled the function of LRP5 on the Norrin/β-catenin signalling. Overexpression of variant-carrying LRP5 proteins resulted in down regulation of the protein levels of β-catenin and the Norrin/β-catenin signalling target genes c-Myc and Glut1.

CONCLUSION

Our study showed that four inherited LRP5 variants can cause autosomal dominant FEVR via down regulation of Norrin/β-catenin signalling and expanded the spectrum of FEVR-associated LRP5 variants.

Canonical Wnt Signaling in the Pathology of Iron Overload-Induced Oxidative Stress and Age-Related Diseases

Iron accumulates in the vital organs with aging. This is associated with oxidative stress, inflammation, and mitochondrial dysfunction leading to age-related disorders. Abnormal iron levels are linked to neurodegenerative diseases, liver injury, cancer, and ocular diseases. Canonical Wnt signaling is an evolutionarily conserved signaling pathway that regulates many cellular functions including cell proliferation, apoptosis, cell migration, and stem cell renewal. Recent evidences indicate that iron regulates Wnt signaling, and iron chelators like deferoxamine and deferasirox can inhibit Wnt signaling and cell growth. Canonical Wnt signaling is implicated in the pathogenesis of many diseases, and there are significant efforts ongoing to develop innovative therapies targeting the aberrant Wnt signaling. This review examines how intracellular iron accumulation regulates Wnt signaling in various tissues and their potential contribution in the progression of age-related diseases.

LRP5 promotes cancer stem cell traits and chemoresistance in colorectal cancer

The overactivation of canonical Wnt/β-catenin pathway and the maintenance of cancer stem cells (CSCs) are essential for the onset and malignant progression of most human cancers. However, their regulatory mechanism in colorectal cancer (CRC) has not yet been well demonstrated. Low-density lipoprotein receptor-related protein 5 (LRP5) has been identified as an indispensable co-receptor with frizzled family members for the canonical Wnt/β-catenin signal transduction. Herein, we show that activation of LRP5 gene promotes CSCs-like phenotypes, including tumorigenicity and drug resistance in CRC cells, through activating the canonical Wnt/β-catenin and IL-6/STAT3 signalling pathways. Clinically, the expression of LRP5 is upregulated in human CRC tissues and closely associated with clinical stages of patients with CRC. Further analysis showed silencing of endogenous LRP5 gene is sufficient to suppress the CSCs-like phenotypes of CRC through inhibiting these two pathways. In conclusion, our findings not only reveal a regulatory cross-talk between canonical Wnt/β-catenin signalling pathway, IL-6/STAT3 signalling pathway and CD133-related stemness that promote the malignant behaviour of CRC, but also provide a valuable target for the diagnosis and treatment of CRC.

Transcriptome-wide association study and eQTL colocalization identify potentially causal genes responsible for human bone mineral density GWAS associations

Genome-wide association studies (GWASs) for bone mineral density (BMD) in humans have identified over 1100 associations to date. However, identifying causal genes implicated by such studies has been challenging. Recent advances in the development of transcriptome reference datasets and computational approaches such as transcriptome-wide association studies (TWASs) and expression quantitative trait loci (eQTL) colocalization have proven to be informative in identifying putatively causal genes underlying GWAS associations. Here, we used TWAS/eQTL colocalization in conjunction with transcriptomic data from the Genotype-Tissue Expression (GTEx) project to identify potentially causal genes for the largest BMD GWAS performed to date. Using this approach, we identified 512 genes as significant using both TWAS and eQTL colocalization. This set of genes was enriched for regulators of BMD and members of bone relevant biological processes. To investigate the significance of our findings, we selected PPP6R3, the gene with the strongest support from our analysis which was not previously implicated in the regulation of BMD, for further investigation. We observed that Ppp6r3 deletion in mice decreased BMD. In this work, we provide an updated resource of putatively causal BMD genes and demonstrate that PPP6R3 is a putatively causal BMD GWAS gene. These data increase our understanding of the genetics of BMD and provide further evidence for the utility of combined TWAS/colocalization approaches in untangling the genetics of complex traits.

Signalling dynamics in embryonic development

In multicellular organisms, cellular behaviour is tightly regulated to allow proper embryonic development and maintenance of adult tissue. A critical component in this control is the communication between cells via signalling pathways, as errors in intercellular communication can induce developmental defects or diseases such as cancer. It has become clear over the last years that signalling is not static but varies in activity over time. Feedback mechanisms present in every signalling pathway lead to diverse dynamic phenotypes, such as transient activation, signal ramping or oscillations, occurring in a cell type- and stage-dependent manner. In cells, such dynamics can exert various functions that allow organisms to develop in a robust and reproducible way. Here, we focus on Erk, Wnt and Notch signalling pathways, which are dynamic in several tissue types and organisms, including the periodic segmentation of vertebrate embryos, and are often dysregulated in cancer. We will discuss how biochemical processes influence their dynamics and how these impact on cellular behaviour within multicellular systems.

The role of Wnt pathway in obesity induced inflammation and diabetes: a review

Diabetes has become a major killer worldwide and at present, millions are affected by it. Being a chronic disease it increases the risk of other diseases ranging from pulmonary disorders to soft tissue infections. The loss of insulin-producing capacity of the pancreatic β-cells is the main reason for the development of the disease. Obesity is a major complication that can give rise to several other diseases such as cancer, diabetes, etc. Visceral adiposity is one of the major factors that play a role in the development of insulin resistance. Obesity causes a chronic low-grade inflammation in the tissues that further increases the chances of developing diabetes. Several pathways have been associated with the development of diabetes due to inflammation caused by obesity. The Wnt pathway is one such candidate pathway that is found to have a controlling effect on the development of insulin resistance. Moreover, the pathway has also been linked to obesity and inflammation. This review aims to find a connection between obesity, inflammation, and diabetes by taking the wnt pathway as the connecting link.

Gentiopicroside promotes the osteogenesis of bone mesenchymal stem cells by modulation of β-catenin-BMP2 signalling pathway

Osteoporosis is characterized by increased bone fragility, and the drugs used at present to treat osteoporosis can cause adverse reactions. Gentiopicroside (GEN), a class of natural compounds with numerous biological activities such as anti‐resorptive properties and protective effects against bone loss. Therefore, the aim of this work was to explore the effect of GEN on bone mesenchymal stem cells (BMSCs) osteogenesis for a potential osteoporosis therapy. In vitro, BMSCs were exposed to GEN at different doses for 2 weeks, whereas in vivo, ovariectomized osteoporosis was established in mice and the therapeutic effect of GEN was evaluated for 3 months. Our results in vitro showed that GEN promoted the activity of alkaline phosphatase, increased the calcified nodules in BMSCs and up‐regulated the osteogenic factors (Runx2, OSX, OCN, OPN and BMP2). In vivo, GEN promoted the expression of Runx2, OCN and BMP2, increased the level of osteogenic parameters, and accelerated the osteogenesis of BMSCs by activating the BMP pathway and Wnt/β‐catenin pathway, effect that was inhibited using the BMP inhibitor Noggin and Wnt/β‐catenin inhibitor DKK1. Silencing the β‐catenin gene and BMP2 gene blocked the osteogenic differentiation induced by GEN in BMSCs. This block was also observed when only β‐catenin was silenced, although the knockout of BMP2 did not affect β‐catenin expression induced by GEN. Therefore, GEN promotes BMSC osteogenesis by regulating β‐catenin‐BMP signalling, providing a novel strategy in the treatment of osteoporosis.

Regulation of the Low-Density Lipoprotein Receptor-Related Protein LRP6 and Its Association With Disease: Wnt/β-Catenin Signaling and Beyond

Wnt signaling plays crucial roles in development and tissue homeostasis, and its dysregulation leads to various diseases, notably cancer. Wnt/β-catenin signaling is initiated when the glycoprotein Wnt binds to and forms a ternary complex with the Frizzled and low-density lipoprotein receptor-related protein 5/6 (LRP5/6). Despite being identified as a Wnt co-receptor over 20 years ago, the molecular mechanisms governing how LRP6 senses Wnt and transduces downstream signaling cascades are still being deciphered. Due to its role as one of the main Wnt signaling components, the dysregulation or mutation of LRP6 is implicated in several diseases such as cancer, neurodegeneration, metabolic syndrome and skeletal disease. Herein, we will review how LRP6 is activated by Wnt stimulation and explore the various regulatory mechanisms involved. The participation of LRP6 in other signaling pathways will also be discussed. Finally, the relationship between LRP6 dysregulation and disease will be examined in detail.

Integrin αEβ7+ T cells direct intestinal stem cell fate decisions via adhesion signaling

Intestinal stem cell (ISC) differentiation is regulated precisely by a niche in the crypt, where lymphocytes may interact with stem and transient amplifying (TA) cells. However, whether and how lymphocyte-stem/TA cell contact affects ISC differentiation is largely unknown. Here, we uncover a novel role of T cell-stem/TA cell contact in ISC fate decisions. We show that intestinal lymphocyte depletion results in skewed ISC differentiation in mice, which can be rescued by T cell transfer. Mechanistically, integrin αEβ7 expressed on T cells binds to E-cadherin on ISCs and TA cells, triggering E-cadherin endocytosis and the consequent Wnt and Notch signaling alterations. Blocking αEβ7-E-cadherin adhesion suppresses Wnt signaling and promotes Notch signaling in ISCs and TA cells, leading to defective ISC differentiation. Thus, αEβ7⁺ T cells regulate ISC differentiation at single-cell level through cell-cell contact-mediated αEβ7-E-cadherin adhesion signaling, highlighting a critical role of the T cell-stem/TA cell contact in maintaining intestinal homeostasis.

An MST4-pβ-CateninThr40 Signaling Axis Controls Intestinal Stem Cell and Tumorigenesis

Elevated Wnt/β-catenin signaling has been commonly associated with tumorigenesis especially colorectal cancer (CRC). Here, an MST4-pβ-cateninThr40 signaling axis essential for intestinal stem cell (ISC) homeostasis and CRC development is uncovered. In response to Wnt3a stimulation, the kinase MST4 directly phosphorylates β-catenin at Thr40 to block its Ser33 phosphorylation by GSK3β. Thus, MST4 mediates an active process that prevents β-catenin from binding to and being degraded by β-TrCP, leading to accumulation and full activation of β-catenin. Depletion of MST4 causes loss of ISCs and inhibits CRC growth. Mice bearing either MST4T178E mutation with constitutive kinase activity or β-cateninT40D mutation mimicking MST4-mediated phosphorylation show overly increased ISCs/CSCs and exacerbates CRC. Furthermore, the MST4-pβ-cateninThr40 axis is upregulated and correlated with poor prognosis of human CRC. Collectively, this work establishes a previously undefined machinery for β-catenin activation, and further reveals its function in stem cell and tumor biology, opening new opportunities for targeted therapy of CRC.

Emerging roles for the YAP/TAZ transcriptional regulators in brain tumour pathology and targeting options

The transcriptional co-activators Yes-associated protein 1/transcriptional co-activator with PDZ-binding motif (YAP/TAZ) have emerged as significant regulators of a wide variety of cellular and organ functions with impact in early embryonic development, especially during the expansion of the neural progenitor cell pool. YAP/TAZ signalling regulates organ size development, tissue homeostasis, wound healing and angiogenesis by participating in a complex network of various pathways. However, recent evidence suggests an association of these physiologic regulatory effects of YAP/TAZ with pro-oncogenic activities. Herein, we discuss the physiological functions of YAP/TAZ as well as the extensive network of signalling pathways that control their expression and activity, leading to brain tumour development and progression. Furthermore, we describe current targeting approaches and drug options including direct YAP/TAZ and YAP-TEA domain transcription factor (TEAD) interaction inhibitors, G-protein coupled receptors (GPCR) signalling modulators and kinase inhibitors, which may be used to successfully attack YAP/TAZ-dependent tumours.

Can We Pharmacologically Target Dishevelled: The Key Signal Transducer in the Wnt Pathways?

Dishevelled (DVL) is the central signal transducer in both Wnt/β-catenin-dependent and independent signalling pathways. DVL is required to connect receptor complexes and downstream effectors. Since proximal Wnt pathway components and DVL itself are upregulated in many types of cancer, DVL represents an attractive therapeutic target in the Wnt-addicted cancers and other disorders caused by aberrant Wnt signalling. Here, we discuss progress in several approaches for the modulation of DVL function and hence inhibition of the Wnt signalling. Namely, we sum up the potential of modulation of enzymes that control post-translational modification of DVL - such as inhibition of DVL kinases or promotion of DVL ubiquitination and degradation. In addition, we discuss research directions that can take advantage of direct interaction with the protein domains essential for DVL function: the inhibition of DIX- and DEP-domain mediated polymerization and interaction of DVL PDZ domain with its ligands.

Amplification of RAD54B promotes progression of hepatocellular carcinoma via activating the Wnt/β-catenin signaling

Liver cancer was reported to be the sixth most frequently diagnosed cancer, and hepatocellular carcinoma (HCC) accounts for 75%-85% of primary liver cancer. Nevertheless, the concrete molecular mechanisms of HCC progression remain obscure, which is essential to elucidate. The expression profile of RAD54B in HCC was measured using qPCR and western blotting. Moreover, the levels of RAD54B in paraffin-embedded samples were evaluated using immunohistochemistry (IHC). The effect of RAD54B on HCC progression was testified by in vitro experiments, and in vivo orthotopic xenograft tumor experiments. The mechanisms of RAD54B promoting HCC progression were investigated through molecular and function experiments. Herein, RAD54B are dramatically upregulated in HCC tissues and cell lines both on mRNA and protein levels, and RAD54B can servers as an independent prognostic parameter of 5-year overall survival and 5-year disease-free survival for patients with HCC. Moreover, up-regulation of RAD54B dramatically increases the capacity for in vitro cell viability and motility, and in vivo intrahepatic metastasis of HCC cells. Mechanistically, RAD54B promotes the HCC progression through modulating the wnt/β-catenin signaling. Notably, blocking the wnt/β-catenin signaling axis can counteract the activating effects of RAD54B on motility of HCC cells. Besides, further analysis illustrates that DNA amplification is one of the mechanisms leading to mRNA overexpression of RAD54B in HCC. Our findings indicate that RAD54B might be a promising potential prognostic marker and a candidate therapeutic target to therapy HCC.

In silico investigations on curcuminoids from Curcuma longa as positive regulators of the Wnt/β-catenin signaling pathway in wound healing

Background

Curcuma longa (Turmeric) is a traditionally used herb in wound healing. The efficacy of fresh turmeric paste to heal wounds has already been investigated in multiple ethnobotanical studies. Wnt/β-catenin signaling pathway plays a significant role in wound healing and injury repair processes which has been evident in different in vitro studies. This study aims to analyze the potentiality of curcuminoids (curcumin I, curcumin II and curcumin III) from Curcuma longa to bind and enhance the activity of two intracellular signaling proteins- casein kinase-1 (CK1) and glycogen synthase kinase-3β (GSK3B) involved in Wnt/β-catenin signaling pathway. This study is largely based on a computer-based molecular docking program which mimics the in vivo condition and works on a specific algorithm to interpret the binding affinity and poses of a ligand molecule to a receptor. Subsequently, drug likeness property, ADME/Toxicity profile, pharmacological activity, and site of metabolism of the curcuminoids were also analyzed.

Results

Curcumin I showed better affinity of binding with CK1 (− 10.31 Kcal/mol binding energy) and curcumin II showed better binding affinity (− 7.55 Kcal/mol binding energy) for GSK3B. All of the ligand molecules showed quite similar pharmacological properties.

Conclusion

Curcumin has anti-oxidant, anti-carcinogenic, anti-mutagenic, anti-coagulant, and anti-infective properties. Curcumin has also anti-inflammatory and wound healing properties. It hastens wound healing by acting on different stages of the natural wound healing process. In this study, three curcumins from Curcuma longa were utilized in this experiment in a search for a drug to be used in wound healing and injury repair processes. Hopefully, this study will raise research interest among researchers.

Expression of Wnt and TGF-Beta Pathway Components during Whole-Body Regeneration from Cell Aggregates in Demosponge Halisarca dujardinii

The phenomenon of whole-body regeneration means rebuilding of the whole body of an animal from a small fragment or even a group of cells. In this process, the old axial relationships are often lost, and new ones are established. An amazing model for studying this process is sponges, some of which are able to regenerate into a definitive organism after dissociation into cells. We hypothesized that during the development of cell aggregates, primmorphs, new axes are established due to the activation of the Wnt and TGF-beta signaling pathways. Using in silico analysis, RNA-seq, and whole-mount in situ hybridization, we identified the participants in these signaling pathways and determined the spatiotemporal changes in their expression in demosponge Halisarca dujardinii. It was shown that Wnt and TGF-beta ligands are differentially expressed during primmorph development, and transcripts of several genes are localized at the poles of primmorphs, in the form of a gradient. We suppose that the Wnt and TGF-beta signaling cascades are involved in the initial axial patterning of the sponge body, which develops from cells after dissociation.

The role of GSK3 in metabolic pathway perturbations in cancer

Malignant transformation and tumor progression are accompanied by significant perturbations in metabolic programs. As such, cancer cells support high ATP turnover to construct the building blocks needed to fuel neoplastic growth. The coordination of metabolic networks in malignant cells is dependent on the collaboration with cellular signaling pathways. Glycogen synthase kinase 3 (GSK3) lies at the convergence of several signaling axes, including the PI3K/AKT/mTOR, AMPK, and Wnt pathways, which influence cancer initiation, progression and therapeutic responses. Accordingly, GSK3 modulates metabolic processes, including protein and lipid synthesis, glucose and mitochondrial metabolism, as well as autophagy. In this review, we highlight current knowledge of the role of GSK3 in metabolic perturbations in cancer.

LRP5 and LRP6 in Wnt Signaling: Similarity and Divergence

The canonical Wnt/β-catenin signaling plays a fundamental role in regulating embryonic development, injury repair and the pathogenesis of human diseases. In vertebrates, low density lipoprotein receptor-related proteins 5 and 6 (LRP5 and LRP6), the single-pass transmembrane proteins, act as coreceptors of Wnt ligands and are indispensable for Wnt signal transduction. LRP5 and LRP6 are highly homologous and widely co-expressed in embryonic and adult tissues, and they share similar function in mediating Wnt signaling. However, they also exhibit distinct characteristics by interacting with different protein partners. As such, each of them possesses its own unique functions. In this review, we systematically discuss the similarity and divergence of LRP5 and LRP6 in mediating Wnt and other signaling in the context of kidney diseases. A better understanding of the precise role of LRP5 and LRP6 may afford us to identify and refine therapeutic targets for the treatment of a variety of human diseases.

Icarisid II promotes proliferation and neuronal differentiation of neural stem cells via activating Wnt/β-catenin signaling pathway

Adult neurogenesis plays a vital role in maintaining cognitive functions in mammals and human beings. Mobilization of hippocampal neurogenesis has been regarded as a promising therapeutic approach to restore injured neurons in neurodegenerative diseases including Alzheimer's disease (AD). Icarisid II (ICS II), an active ingredient derived from Epimedii Folium, has been reported to exhibit multiple neuroprotective effects. In the present study, we investigated the effects of ICS II on the proliferation and differentiation of neural stem cells (NSCs) and amyloid precusor protein (APP)-overexpressing NSCs (APP-NSCs) in vitro. Our results demonstrated that ICS II dose-dependently suppressed apoptosis and elevated viability of APP-NSCs. ICS II (1 μM) potently promoted proliferation and neuronal differentiation of NSCs and APP-NSCs. ICS II (1 μM) significantly upregulated Wnt-3a expression, increased the phosphorylation of glycogen synthase kinase-3β and enhanced the nuclear transfer of β-catenin. Moreover, ICS II also promoted astrocytes to secrete Wnt-3a, which positively modulates Wnt/β-catenin signaling pathway. These findings demonstrate that ICS II promotes NSCs proliferation and neuronal differentiation partly by activating the Wnt/β-catenin signaling pathway.

Targeting the crosstalk between canonical Wnt/β-catenin and inflammatory signaling cascades: A novel strategy for cancer prevention and therapy

Emerging scientific evidence indicates that inflammation is a critical component of tumor promotion and progression. Most cancers originate from sites of chronic irritation, infections and inflammation, underscoring that the tumor microenvironment is largely orchestrated by inflammatory cells and pro-inflammatory molecules. These inflammatory components are intimately involved in neoplastic processes which foster proliferation, survival, invasion, and migration, making inflammation the primary target for cancer prevention and treatment. The influence of inflammation and the immune system on the progression and development of cancer has recently gained immense interest. The Wnt/β-catenin signaling pathway, an evolutionarily conserved signaling strategy, has a critical role in regulating tissue development. It has been implicated as a major player in cancer development and progression with its regulatory role on inflammatory cascades. Many naturally-occurring and small synthetic molecules endowed with inherent anti-inflammatory properties inhibit this aberrant signaling pathway, making them a promising class of compounds in the fight against inflammatory cancers. This article analyzes available scientific evidence and suggests a crosslink between Wnt/β-catenin signaling and inflammatory pathways in inflammatory cancers, especially breast, gastrointestinal, endometrial, and ovarian cancer. We also highlight emerging experimental findings that numerous anti-inflammatory synthetic and natural compounds target the crosslink between Wnt/β-catenin pathway and inflammatory cascades to achieve cancer prevention and intervention. Current challenges, limitations, and future directions of research are also discussed.

Zbed3 Is Indispensable for Wnt Signaling Regulation of Cortical Layers Formation in Developing Brain

Wnt/β-catenin signaling plays multiple important roles during mammalian brain development, and it regulates the proliferation and differentiation of neural progenitors in a context-dependent manner and affects neocortex layer formation. However, the specific role of Wnt/β-catenin in neuronal layer fate determination in the neocortex is still unclear. Here, we report that Zbed3, which is a positive regulator of Wnt/β-catenin signaling, colocalizes with β-catenin at the endfeet of radial glia in the ventricular zone of embryo mouse neocortex. Overexpression and knockdown of Zbed3 increased and decreased the activity of Wnt/β-catenin signaling in the neocortex, respectively. Interestingly, knockdown of Zbed3 in vivo could significantly shift neuronal fates from deep layers to upper layers but is not required for the proliferation and differentiation of neural progenitors. Overexpression of Zbed3 led to increased generation of deep-layer neurons without impairing cell cycle exit of neural progenitors. More importantly, knockdown of Zbed3 could effectively block the effects of the ectopic expression of stabilized β-catenin on neocortex layer formation. Hence, our results demonstrate that Zbed3 is indispensable for Wnt/β-catenin signaling regulating neuronal layer fates in the developing brain.

Lipoprotein receptor signalling in atherosclerosis

The founding member of the lipoprotein receptor family, low-density lipoprotein receptor (LDLR) plays a major role in the atherogenesis through the receptor-mediated endocytosis of LDL particles and regulation of cholesterol homeostasis. Since the discovery of the LDLR, many other structurally and functionally related receptors have been identified, which include low-density lipoprotein receptor-related protein (LRP)1, LRP5, LRP6, very low-density lipoprotein receptor, and apolipoprotein E receptor 2. The scavenger receptor family members, on the other hand, constitute a family of pattern recognition proteins that are structurally diverse and recognize a wide array of ligands, including oxidized LDL. Among these are cluster of differentiation 36, scavenger receptor class B type I and lectin-like oxidized low-density lipoprotein receptor-1. In addition to the initially assigned role as a mediator of the uptake of macromolecules into the cell, a large number of studies in cultured cells and in in vivo animal models have revealed that these lipoprotein receptors participate in signal transduction to modulate cellular functions. This review highlights the signalling pathways by which these receptors influence the process of atherosclerosis development, focusing on their roles in the vascular cells, such as macrophages, endothelial cells, smooth muscle cells, and platelets. Human genetics of the receptors is also discussed to further provide the relevance to cardiovascular disease risks in humans. Further knowledge of the vascular biology of the lipoprotein receptors and their ligands will potentially enhance our ability to harness the mechanism to develop novel prophylactic and therapeutic strategies against cardiovascular diseases.

LRPs in WNT Signalling

The WNT/β-catenin signalling pathway is a rich and complex network of cellular proteins that orchestrates diverse short-range cell-to-cell communication in metazoans and is essential for both embryonic development and adult homeostasis. Due to its fundamental importance in controlling cell behaviour at multiple levels, its deregulation is associated with a wide range of diseases in humans and identification of drugs targeting the pathway has attracted strong interest in the pharmaceutical sector. Transduction of WNT signals across the plasma membrane of cells involves a staggering degree of complexity and variety with respect to ligand-receptor, receptor-receptor and receptor-co-receptor interactions (Niehrs, Nat Rev Mol Cell Biol 13:767-779, 2012). Although the low-density-lipoprotein-receptor-related-protein (LRP) family is best known for its role in binding and endocytosis of lipoproteins, specific members appear to have additional roles in cellular communication. Indeed, for WNT/β-catenin signalling one apparently universal requirement is the presence of either LRP5 or LRP6 in combination with one of the ten Frizzled (FZD) WNT receptors (FZD_1-10). In the 20 years since their discovery as WNT/FZD co-receptors, research on the LRP family has contributed greatly to our understanding of WNT signalling and LRPs have emerged as central players in WNT/β-catenin signalling. LRP5/6 are highly similar and represent the least redundant class of WNT receptor that transduce WNT/β-catenin signalling from a wide range of different WNT and FZD subtypes. This apparent simplicity however belies the complex arrangement of binding sites in the extracellular domain (ECD) of LRP5/6, which regulate interaction not only with WNTs but also with several inhibitors of WNT signalling. This chapter provides a historical overview, chronologically charting this remarkable progress in the field during the last 20 years of research on LRPs and their role in WNT/-catenin signalling. A more focused overview of the structural, functional and mechanistic aspects of LRP biology is also provided, together with the implications this has for pharmacological targeting of this notoriously intractable pathway.

Mutations and mechanisms of WNT pathway tumour suppressors in cancer

Mutation-induced activation of WNT-β-catenin signalling is a frequent driver event in human cancer. Sustained WNT-β-catenin pathway activation endows cancer cells with sustained self-renewing growth properties and is associated with therapy resistance. In healthy adult stem cells, WNT pathway activity is carefully controlled by core pathway tumour suppressors as well as negative feedback regulators. Gene inactivation experiments in mouse models unequivocally demonstrated the relevance of WNT tumour suppressor loss-of-function mutations for cancer growth. However, in human cancer, a far more complex picture has emerged in which missense or truncating mutations mediate stable expression of mutant proteins, with distinct functional and phenotypic ramifications. Herein, we review recent advances and challenges in our understanding of how different mutational subsets of WNT tumour suppressor genes link to distinct cancer types, clinical outcomes and treatment strategies.

Zooming in on the WNT/CTNNB1 Destruction Complex: Functional Mechanistic Details with Implications for Therapeutic Targeting

WNT/CTNNB1 signaling is crucial for balancing cell proliferation and differentiation in all multicellular animals. CTNNB1 accumulation is the hallmark of WNT/CTNNB1 pathway activation and the key downstream event in both a physiological and an oncogenic context. In the absence of WNT stimulation, the cytoplasmic and nuclear levels of CTNNB1 are kept low because of its sequestration and phosphorylation by the so-called destruction complex, which targets CTNNB1 for proteasomal degradation. In the presence of WNT proteins, or as a result of oncogenic mutations, this process is impaired and CTNNB1 levels become elevated.Here we discuss recent advances in our understanding of destruction complex activity and inactivation, focusing on the individual components and interactions that ultimately control CTNNB1 turnover (in the "WNT off" situation) and stabilization (in the "WNT on" situation). We especially highlight the insights gleaned from recent quantitative, image-based studies, which paint an unprecedentedly detailed picture of the dynamic events that control destruction protein complex composition and function. We argue that these mechanistic details may reveal new opportunities for therapeutic intervention and could result in the destruction complex re-emerging as a target for therapy in cancer.

A Dynamic Role of Mastermind-Like 1: A Journey Through the Main (Path)ways Between Development and Cancer

Major signaling pathways, such as Notch, Hedgehog (Hh), Wnt/β-catenin and Hippo, are targeted by a plethora of physiological and pathological stimuli, ultimately resulting in the modulation of genes that act coordinately to establish specific biological processes. Many biological programs are strictly controlled by the assembly of multiprotein complexes into the nucleus, where a regulated recruitment of specific transcription factors and coactivators on gene promoter region leads to different transcriptional outcomes. MAML1 results to be a versatile coactivator, able to set up synergistic interlinking with pivotal signaling cascades and able to coordinate the network of cross-talking pathways. Accordingly, despite its original identification as a component of the Notch signaling pathway, several recent reports suggest a more articulated role for MAML1 protein, showing that it is able to sustain/empower Wnt/β-catenin, Hh and Hippo pathways, in a Notch-independent manner. For this reason, MAML1 may be associated to a molecular “switch”, with the function to control the activation of major signaling pathways, triggering in this way critical biological processes during embryonic and post-natal life. In this review, we summarize the current knowledge about the pleiotropic role played by MAML proteins, in particular MAML1, and we recapitulate how it takes part actively in physiological and pathological signaling networks. On this point, we also discuss the contribution of MAML proteins to malignant transformation. Accordingly, genetic alterations or impaired expression of MAML proteins may lead to a deregulated crosstalk among the pathways, culminating in a series of pathological disorders, including cancer development. Given their central role, a better knowledge of the molecular mechanisms that regulate the interplay of MAML proteins with several signaling pathways involved in tumorigenesis may open up novel opportunities for an attractive molecular targeted anticancer therapy.

Molecular and Cellular Mechanisms Associated with Effects of Molecular Hydrogen in Cardiovascular and Central Nervous Systems

The increased production of reactive oxygen species and oxidative stress are important factors contributing to the development of diseases of the cardiovascular and central nervous systems. Molecular hydrogen is recognized as an emerging therapeutic, and its positive effects in the treatment of pathologies have been documented in both experimental and clinical studies. The therapeutic potential of hydrogen is attributed to several major molecular mechanisms. This review focuses on the effects of hydrogen on the cardiovascular and central nervous systems, and summarizes current knowledge about its actions, including the regulation of redox and intracellular signaling, alterations in gene expressions, and modulation of cellular responses (e.g., autophagy, apoptosis, and tissue remodeling). We summarize the functions of hydrogen as a regulator of nuclear factor erythroid 2-related factor 2 (Nrf2)-mediated redox signaling and the association of hydrogen with mitochondria as an important target of its therapeutic action. The antioxidant functions of hydrogen are closely associated with protein kinase signaling pathways, and we discuss possible roles of the phosphoinositide 3-kinase/protein kinase B (PI3K/Akt) and Wnt/β-catenin pathways, which are mediated through glycogen synthase kinase 3β and its involvement in the regulation of cellular apoptosis. Additionally, current knowledge about the role of molecular hydrogen in the modulation of autophagy and matrix metalloproteinases-mediated tissue remodeling, which are other responses to cellular stress, is summarized in this review.

Tumor microenvironment pathways: Cross regulation in breast cancer metastasis

The tumor microenvironment (TME) is heterogeneous and contains a multiple cell population with surrounded immune cells, which plays a major role in regulating metastasis. The multifunctional pathways, Hedgehog (Hh), Wnt, Notch, and NF-kB, cross-regulates metastasis in breast cancer. This review presents substantial evidence for cross-regulation of TME components and signaling pathways, which makes breast TME more heterogeneous and complex, promoting breast cancer progression and metastasis as a highly aggressive form. We discoursed the importance of stromal and immune cells as well as their crosstalk in bridging the metastasis. We also discussed the role of Hh and Notch pathways in the intervention between breast cancer cells and macrophages to support TME; Notch signaling in the bidirectional communication between cancer cells and components of TME; Wnt signal pathway in controlling the factors responsible for EMT and NF-κB pathway in the regulation of genes controlling the inflammatory response. We also present the role of exosomes and their miRNAs in the cross-regulation of TME cells as well as pathways in the reprogramming of breast TME to support metastasis. Finally, we examined and discussed the targeted small molecule inhibitors and natural compounds targeting developmental pathways and proposed small molecule natural compounds as potential therapeutics of TME based on the multitargeting ability. In conclusion, the understanding of the molecular basis of the cross-regulation of TME pathways and their inhibitors helps identify molecular targets for rational drug discovery to treat breast cancers.

Wnt signaling in breast cancer: biological mechanisms, challenges and opportunities

Wnt signaling is a highly conserved signaling pathway that plays a critical role in controlling embryonic and organ development, as well as cancer progression. Genome-wide sequencing and gene expression profile analyses have demonstrated that Wnt signaling is involved mainly in the processes of breast cancer proliferation and metastasis. The most recent studies have indicated that Wnt signaling is also crucial in breast cancer immune microenvironment regulation, stemness maintenance, therapeutic resistance, phenotype shaping, etc. Wnt/β-Catenin, Wnt-planar cell polarity (PCP), and Wnt-Ca2+ signaling are three well-established Wnt signaling pathways that share overlapping components and play different roles in breast cancer progression. In this review, we summarize the main findings concerning the relationship between Wnt signaling and breast cancer and provide an overview of existing mechanisms, challenges, and potential opportunities for advancing the therapy and diagnosis of breast cancer.

Effect of Klotho protein during porcine oocyte maturation via Wnt signaling

Klotho protein is well-known as an anti-aging agent, however, several studies have suggested that Klotho protein also increases antioxidant activity and the reproductive system, as Klotho protein is closely associated with Wnt signaling. The objective of our study was to investigate the enhancement of porcine oocyte in vitro maturation via the Klotho protein-Wnt signaling pathway. Following immunohistochemistry and ELISA, we treated cells with Klotho protein during in vitro maturation. Lithium Chloride, a specific activator of Wnt signaling, was subsequently co-administered with Klotho protein. Mature oocytes subjected to treatments were used for the analysis of embryonic development, qRT-PCR, and immunocytochemistry. Treatment with 5pg/ml Klotho protein significantly increased cumulus cell expansion, blastocyst formation rates, and the total cell number of blastocysts. During cotreatment with 5mM Lithium Chloride and 5pg/ml Klotho protein, blastocyst formation rates were the highest in Klotho protein-treated oocytes and the lowest in Lithium Chloride-treated oocytes. Expression levels of Wnt signaling-related transcripts and proteins were significantly impacted by Klotho protein and Lithium Chloride. Moreover, cellular ATP levels and antioxidant activities were enhanced by Klotho protein treatment. These findings suggest a significant involvement of the Klotho protein-Wnt signaling mechanism in porcine oocyte maturation.

RNF43 truncations trap CK1 to drive niche-independent self-renewal in cancer

Wnt/β-catenin signaling is a primary pathway for stem cell maintenance during tissue renewal and a frequent target for mutations in cancer. Impaired Wnt receptor endocytosis due to loss of the ubiquitin ligase RNF43 gives rise to Wnt-hypersensitive tumors that are susceptible to anti-Wnt-based therapy. Contrary to this paradigm, we identify a class of RNF43 truncating cancer mutations that induce β-catenin-mediated transcription, despite exhibiting retained Wnt receptor downregulation. These mutations interfere with a ubiquitin-independent suppressor role of the RNF43 cytosolic tail that involves Casein kinase 1 (CK1) binding and phosphorylation. Mechanistically, truncated RNF43 variants trap CK1 at the plasma membrane, thereby preventing β-catenin turnover and propelling ligand-independent target gene transcription. Gene editing of human colon stem cells shows that RNF43 truncations cooperate with p53 loss to drive a niche-independent program for self-renewal and proliferation. Moreover, these RNF43 variants confer decreased sensitivity to anti-Wnt-based therapy. Our data demonstrate the relevance of studying patient-derived mutations for understanding disease mechanisms and improved applications of precision medicine.

The Daam2-VHL-Nedd4 axis governs developmental and regenerative oligodendrocyte differentiation

Dysregulation of the ubiquitin-proteasomal system (UPS) enables pathogenic accumulation of disease-driving proteins in neurons across a host of neurological disorders. However, whether and how the UPS contributes to oligodendrocyte dysfunction and repair after white matter injury (WMI) remains undefined. Here we show that the E3 ligase VHL interacts with Daam2 and their mutual antagonism regulates oligodendrocyte differentiation during development. Using proteomic analysis of the Daam2-VHL complex coupled with conditional genetic knockout mouse models, we further discovered that the E3 ubiquitin ligase Nedd4 is required for developmental myelination through stabilization of VHL via K63-linked ubiquitination. Furthermore, studies in mouse demyelination models and white matter lesions from patients with multiple sclerosis corroborate the function of this pathway during remyelination after WMI. Overall, these studies provide evidence that a signaling axis involving key UPS components contributes to oligodendrocyte development and repair and reveal a new role for Nedd4 in glial biology.

Glioblastoma stem cells and Wnt signaling pathway: molecular mechanisms and therapeutic targets

Glioblastoma is the most common form of primary brain tumor. Glioblastoma stem cells play an important role in tumor formation by activation of several signaling pathways. Wnt signaling pathway is one such important pathway which helps cellular differentiation to promote tumor formation in the brain. Glioblastoma remains to be a highly destructive type of tumor despite availability of treatment strategies like surgery, chemotherapy, and radiation. Advances in the field of cancer biology have revolutionized therapy by allowing targeting of tumor-specific molecular deregulation. In this review, we discuss about the significance of glioblastoma stem cells in cancer progression through Wnt signaling pathway and highlight the clinical targets being potentially considered for therapy in glioblastoma.

WISP-2 expression induced by Teriparatide treatment affects in vitro osteoblast differentiation and improves in vivo osteogenesis

The Osteocyte, recognized as a major orchestrator of osteoblast and osteoclast activity, is the most important key player during bone remodeling processes. Imbalances occurring during bone remodeling, caused by hormone perturbations or by mechanical loading alterations, can induce bone pathologies such as osteoporosis. Recently, the active fraction of parathormone, PTH (1-34) or Teriparatide (TPTD), was chosen as election treatment for osteoporosis. The effect of such therapy is dependent on the temporal manner of administration. The molecular reasons why the type of administration regimen is so critical for the fate of bone remodeling are numerous and not yet well known. Our study attempts to analyze diverse signaling pathways directly activated in osteocytes upon TPTD treatment. By means of gene array analysis, we found many molecules upregulated or downregulated in osteocytes. Later, we paid attention to Wisp-2, a protein involved in the Wnt pathway, that is secreted by MLO-Y4 cells and increases upon TPTD treatment and that is able to positively influence the early phases of osteogenic differentiation. We also confirmed the pro osteogenic property of Wisp-2 during mesenchymal stem cell differentiation into the preliminary osteoblast phenotype. The same results were confirmed with an in vivo approach confirming a remarkable Wisp-2 expression in metaphyseal trabecular bone. These results highlighted the anabolic roles unrolled by osteocytes in controlling the action of neighboring cells, suggesting that the perturbation of certain signaling cascades, such as the Wnt pathway, is crucial for the positive regulation of bone formation.

Piperine suppresses the Wnt/β-catenin pathway and has anti-cancer effects on colorectal cancer cells

More than 94% of colorectal cancer cases have mutations in one or more Wnt/β-catenin signaling pathway components. Inactivating mutations in APC or activating mutations in β-catenin (CTNNB1) lead to signaling overactivation and subsequent intestinal hyperplasia. Numerous classes of medicines derived from synthetic or natural small molecules, including alkaloids, have benefited the treatment of different diseases, including cancer, Piperine is a true alkaloid, derived from lysine, responsible for the spicy taste of black pepper (Piper nigrum) and long pepper (Piper longum). Studies have shown that piperine has a wide range of pharmacological properties; however, piperine molecular mechanisms of action are still not fully understood. By using Wnt/β-catenin pathway epistasis experiment we show that piperine inhibits the canonical Wnt pathway induced by overexpression of β-catenin, β-catenin S33A or dnTCF4 VP16, while also suppressing β-catenin nuclear localization in HCT116 cell line. Additionally, piperine impairs cell proliferation and migration in HCT116, SW480 and DLD-1 colorectal tumor cell lines, while not affecting the non-tumoral cell line IEC-6. In summary, piperine inhibits the canonical Wnt signaling pathway and displays anti-cancer effects on colorectal cancer cell lines.

WNT Signaling in Melanoma

WNT-signaling controls important cellular processes throughout embryonic development and adult life, so any deregulation of this signaling can result in a wide range of pathologies, including cancer. WNT-signaling is classified into two categories: β-catenin-dependent signaling (canonical pathway) and β-catenin-independent signaling (non-canonical pathway), the latter can be further divided into WNT/planar cell polarity (PCP) and calcium pathways. WNT ligands are considered as unique directional growth factors that contribute to both cell proliferation and polarity. Origin of cancer can be diverse and therefore tissue-specific differences can be found in WNT-signaling between cancers, including specific mutations contributing to cancer development. This review focuses on the role of the WNT-signaling pathway in melanoma. The current view on the role of WNT-signaling in cancer immunity as well as a short summary of WNT pathway-related drugs under investigation are also provided.

A novel role of LRP5 in tubulointerstitial fibrosis through activating TGF-β/Smad signaling

Previous studies by us and others demonstrated that activation of Wnt/β-catenin signaling plays a pathogenic role in chronic kidney diseases (CKD). Wnt co-receptor LRP5 variants are reported to associate with autosomal dominant polycystic kidney disease; but their exact roles in this disease and renal fibrosis have not been explored. Here, we observed the upregulation of LRP5 in the renal tubules of both type 1 and type 2 diabetic models and of an obstructive nephropathy model. In the obstructed kidneys, Lrp5 knockout significantly ameliorated tubulointerstitial fibrosis and tubular injury without changing Wnt/β-catenin signaling. Instead, decreased levels of TGF-β1 and TGF-β receptors (TβRs) were detected in Lrp5 knockout kidneys, followed by attenuated activation and nuclear translocation of Smad2/3 in the renal tubules, suggesting a regulatory effect of LRP5 on TGF-β/Smad signaling. In consistent with this hypothesis, LRP5 overexpression resulted in enhanced TGF-β/Smad signaling activation in renal tubule epithelial cells. Furthermore, LRP5 was co-immunoprecipitated with TβRI and TβRII, and its extracellular domain was essential for interacting with TβRs and for its pro-fibrotic activity. In addition to stabilizing TβRs, LRP5 increased the basal membrane presentation and TGF-β1-induced internalization of these receptors. Notably, TGF-β1 also induced LRP5 internalization. These findings indicate that LRP5 promotes tubulointerstitial fibrosis, at least partially, via direct modulation of TGF-β/Smad signaling, a novel, Wnt-independent function.

Frizzled 6 disruption suppresses osteoblast differentiation induced by nanotopography through the canonical Wnt signaling pathway

This study aimed to investigate if wingless-related integration site (Wnt) signaling participates in the high osteogenic potential of titanium with nanotopography (Ti-Nano). We showed that among the several components of the Wnt signaling pathway, Frizzled 6 (Fzd6) was the transcript most intensely modulated by nanotopography compared with the untreated Ti surface (Ti-Machined). Then, we investigated whether and how Fzd6 participates in the regulation of osteoblast differentiation caused by nanotopography. The Fzd6 silencing with CRISPR-Cas9 transfection in MC3T3-E1 cells induced a more pronounced inhibition of osteoblast differentiation of cells cultured on nanotopography than those cultured on Ti-Machined. The analysis of the expression of calcium-calmodulin-dependent protein kinase II and β-catenin demonstrated that Fzd6 disruption inhibited the osteoblast differentiation induced by Ti-Nano by preventing the activation of Wnt/β-catenin but not that of Wnt/Ca²⁺ signaling, which is usually triggered by the receptor Fzd6. These findings elucidate the biological function of Fzd6 as a receptor that triggers Wnt/β-catenin signaling and the cellular mechanisms modulated by nanotopography during osteoblast differentiation.

The physiological role of Wnt pathway in normal development and cancer

Over the decades, many studies have illustrated the critical roles of Wnt signaling pathways in both developmental processes as well as tumorigenesis. Due to the complexity of Wnt signaling regulation, there are still questions to be addressed about ways cells are able to manipulate different types of Wnt pathways in order to fulfill the requirements for normal or cancer development. In this review, we will describe different types of Wnt signaling pathways and their roles in both normal developmental processes and their role in cancer development and progression. Additionally, we will briefly introduce new strategies currently in clinical trials targeting Wnt signaling pathway components for cancer therapy.

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

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

AXIN2 and SNAIL expression predict the risk of recurrence in cutaneous squamous cell carcinoma after Mohs micrographic surgery

Recurrence is a common complication observed during cutaneous squamous cell carcinoma (cSCC) treatment; however, biomarkers for predicting recurrence in cSCC remain unknown. The present study aimed to investigate the predictive value of axis inhibition protein 2 (AXIN2) and SNAIL expression in cSCC recurrence. AXIN2 and SNAIL expression was evaluated using immunohistochemistry in 111 cSCC tissue samples obtained from 18 patients who presented recurrence (recurrence interval, 1–91 months) and 93 patients who did not experience recurrence following Mohs micrographic surgery (MMS) during the follow-up period (156 months). Nomogram construction was performed using patients' clinicopathological characteristics and AXIN2 and SNAIL protein expression. The results demonstrated that high AXIN2 (histoscore >100) and SNAIL (histoscore >100) expression was detected in 35 and 44 cSCC tissues, respectively. Furthermore, the expression levels of AXIN2 and SNAIL were significantly associated in patients with cSCC (P=0.001). AXIN2 and SNAIL expression levels were significantly associated with tumor size (P=0.021 and P=0.044, respectively) and recurrence of cSCC (P=0.017 and P=0.042, respectively). In addition, the results of the Kaplan-Meier curve analysis revealed that recurrence-free survival was significantly associated with tumor size (P=0.025), differentiation status (P<0.001), AXIN2 expression (P=0.001) and SNAIL expression (P=0.001). Furthermore, the results of the multivariate analysis demonstrated that age (P=0.043), AXIN2 expression (P=0.001) and SNAIL expression (P=0.045) were independent risk factors for cSCC recurrence in the present cohort. A nomogram for predicting the 1-, 2-, 3-, and 5-year recurrence-free survival was developed for patients with cSCC by including independent risk factors with a concordance index of 0.75. The results suggested that high AXIN2 and SNAIL expression may be considered as potential risk factors for cSCC recurrence. This nomogram may therefore be useful to assess the probability of recurrence in patients with cSCC following MMS.

Growth control in the Drosophila wing disk

The regulation of size and shape is a fundamental requirement of biological development and has been a subject of scientific study for centuries, but we still lack an understanding of how organisms know when to stop growing. Imaginal wing disks of the fruit fly Drosophila melanogaster, which are precursors of the adult wings, are an archetypal tissue for studying growth control. The growth of the disks is dependent on many inter- and intra-organ factors such as morphogens, mechanical forces, nutrient levels, and hormones that influence gene expression and cell growth. Extracellular signals are transduced into gene-control signals via complex signal transduction networks, and since cells typically receive many different signals, a mechanism for integrating the signals is needed. Our understanding of the effect of morphogens on tissue-level growth regulation via individual pathways has increased significantly in the last half century, but our understanding of how multiple biochemical and mechanical signals are integrated to determine whether or not a cell decides to divide is still rudimentary. Numerous fundamental questions are involved in understanding the decision-making process, and here we review the major biochemical and mechanical pathways involved in disk development with a view toward providing a basis for beginning to understand how multiple signals can be integrated at the cell level, and how this translates into growth control at the level of the imaginal disk. This article is categorized under: Analytical and Computational Methods > Computational Methods Biological Mechanisms > Cell Signaling Models of Systems Properties and Processes > Cellular Models.

Attenuation of Wnt/β-catenin signaling in patients with Stevens-Johnson syndrome and toxic epidermal necrolysis

Stevens-Johnson syndrome (SJS) and toxic epidermal necrosis (TEN) are rare but life-threatening severe cutaneous adverse reactions. Current studies have suggested that the pathobiology of drug-mediated SJS/TEN involves a dysregulation of cellular immunity with overwhelming activation of cytotoxic T lymphocytes. The canonical Wnt signaling pathway plays important roles in T cell development and activation, which may provide potential avenues for alleviating dysregulated immunity in SJS/TEN. In this study, we aimed to assess the implication of Wnt signaling in drug-reactive T cells in SJS/TEN. We showed downregulation of Wnt signaling components, including T cell factor 1 (TCF-1)/lymphoid enhancer binding factor 1 (LEF-1) transcription factors, in SJS/TEN patients, suggesting that canonical Wnt signaling is regulated during cytotoxic T cell responses in SJS/TEN. Further analyses demonstrated that engagement of the T cell receptor by antigen encounter and treatment of a prognostic marker of SJS/TEN, IL-15, in vitro led to the downregulation of LEF-1 and TCF-1 expression in CD8+ T cells. Enhancement of Wnt signaling by adding the Wnt activators attenuated ex vivo activation of drug-specific T cells from SJS/TEN patients, indicating a functional involvement of Wnt signaling in the pathomechanism of SJS/TEN. These findings provide additional insight into the immunopathogenesis and therapeutic intervention of this devastating condition.

Wnt Signaling and Its Significance Within the Tumor Microenvironment: Novel Therapeutic Insights

Wnt signaling is one of the central mechanisms regulating tissue morphogenesis during embryogenesis and repair. The pivot of this signaling cascade is the Wnt ligand, which binds to receptors belonging to the Frizzled family or the ROR1/ROR2 and RYK family. This interaction governs the downstream signaling cascade (canonical/non-canonical), ultimately extending its effect on the cellular cytoskeleton, transcriptional control of proliferation and differentiation, and organelle dynamics. Anomalous Wnt signaling has been associated with several cancers, the most prominent ones being colorectal, breast, lung, oral, cervical, and hematopoietic malignancies. It extends its effect on tumorigenesis by modulating the tumor microenvironment via fine crosstalk between transformed cells and infiltrating immune cells, such as leukocytes. This review is an attempt to highlight the latest developments in the understanding of Wnt signaling in the context of tumors and their microenvironment. A dynamic process known as immunoediting governs the fate of tumor progression based on the correlation of various signaling pathways in the tumor microenvironment and immune cells. Cancer cells also undergo a series of mutations in the tumor suppressor gene, which favors tumorigenesis. Wnt signaling, and its crosstalk with various immune cells, has both negative as well as positive effects on tumor progression. On one hand, it helps in the maintenance and renewal of the leucocytes. On the other hand, it promotes immune tolerance, limiting the antitumor response. Wnt signaling also plays a role in epithelial-mesenchymal transition (EMT), thereby promoting the maintenance of Cancer Stem Cells (CSCs). Furthermore, we have summarized the ongoing strategies used to target aberrant Wnt signaling as a novel therapeutic intervention to combat various cancers and their limitations.

Circular RNAs Regulate Cancer Onset and Progression via Wnt/β-Catenin Signaling Pathway

Cancer remains to be a major challenge for public health providers, and is the second leading cause of death worldwide. Therefore, it is imperative to explore the mechanisms underlying cancer initiation and development, and design novel diagnostics and therapeutics. Circular RNAs (circRNAs), which exhibit a covalently closed loop structure, are involved in a variety of diseases, including cancer. The aberrant expression of circRNAs contributes to the initiation and development of various cancers by disrupting the interplay of specific signaling pathways, including the Wnt/β-catenin pathway, which controls a plethora of cellular processes that drive cancer development. The interactions between circRNAs (specifically expressed in different cancer tissues) and Wnt/β-catenin signaling pathway presents potential diagnostic biomarkers and novel therapeutic targets. In this review, we have summarized research discoveries on the functions of Wnt/β-catenin pathway-related circRNAs in the modulation of oncogenesis and progression of different types of cancer. We anticipate that our findings will contribute to the improvement or development of circRNAs-based strategies for cancer treatment.

Carbamazepine Enhances Adipogenesis by Inhibiting Wnt/β-catenin Expression

Carbamazepine is a drug that is widely used in the treatment of epilepsy and bipolar disorder. The prevalence of obesity in patients treated with carbamazepine has been frequently reported. However, whether carbamazepine affects adipogenesis, one of the critical steps in the development of obesity, remains unclear. Here, we show that carbamazepine increased the expression levels of peroxisome proliferator-activated receptor γ (PPARγ), CCAAT/enhancer-binding protein β (C/EBPβ), and fatty acid synthase (FASN) in 3T3-L1 cells. Notably, carbamazepine inhibited the expression levels of β-catenin, a negative regulator of adipogenesis, leading to enhanced adipogenesis. Conversely, β-catenin overexpression abolished the effect of carbamazepine on adipogenic gene expression. However, depletion of β-catenin further enhanced PPARγ expression. In addition, carbamazepine reduced β-catenin expression by lowering the levels of phospho-low density lipoprotein receptor-related protein 6 (p-LRP6) and phospho-glycogen synthase kinase 3β (p-GSK3β) in Wnt/β-catenin signaling. Moreover, carbamazepine reduced Wnt mRNA expression and decreased the promoter activities of TCF, the target of β-catenin during adipogenesis. These results suggest that carbamazepine enhances adipogenesis by suppressing Wnt/β-catenin expression, indicating its potential effects on obesity-related metabolism.