Modulating the wnt signaling pathway with small molecules

Tailoring Biomaterials Ameliorate Inflammatory Bone Loss

Inflammatory diseases, such as rheumatoid arthritis, periodontitis, chronic obstructive pulmonary disease, and celiac disease, disrupt the delicate balance between bone resorption and formation, leading to inflammatory bone loss. Conventional approaches to tackle this issue encompass pharmaceutical interventions and surgical procedures. Nevertheless, pharmaceutical interventions exhibit limited efficacy, while surgical treatments impose trauma and significant financial burden upon patients. Biomaterials show outstanding spatiotemporal controllability, possess a remarkable specific surface area, and demonstrate exceptional reactivity. In the present era, the advancement of emerging biomaterials has bestowed upon more efficacious solutions for combatting the detrimental consequences of inflammatory bone loss. In this review, the advances of biomaterials for ameliorating inflammatory bone loss are listed. Additionally, the advantages and disadvantages of various biomaterials-mediated strategies are summarized. Finally, the challenges and perspectives of biomaterials are analyzed. This review aims to provide new possibilities for developing more advanced biomaterials toward inflammatory bone loss.

Evaluation of Wnt/β-catenin signaling and its modulators in repeated dose lithium-pilocarpine rat model of status epilepticus: An acute phase study

The role of the Wnt/β-catenin signaling pathway in epilepsy and the effects of its modulators as efficacious treatment options, though postulated, has not been sufficiently investigated. We evaluated the involvement of β-catenin and GSK-3β, the significant proteins in this pathway, in the lithium chloride-pilocarpine-induced status epilepticus model in rodents to study acute phase of temporal lobe epilepsy (TLE). The modulators studied were 6-BIO, a GSK-3β inhibitor and Sulindac, a Dvl protein inhibitor. The disease group exhibited increased seizure score and seizure frequency, and the assessment of neurobehavioral parameters indicated notable alterations. Furthermore, histopathological examination of hippocampal brain tissues revealed significant neurodegeneration. Immunohistochemical study of hippocampus revealed neurogenesis in 6-BIO and sulindac groups. The gene and protein expression by RT-qPCR and western blotting studies indicated Wnt/β-catenin pathway downregulation and increased apoptosis in the acute phase of TLE. 6-BIO was very efficient in upregulating the Wnt pathway, decreasing neuronal damage, increasing neurogenesis in hippocampus and decreasing seizure score and frequency in comparison to sulindac. This suggests that both GSK-3β and β-catenin are potential and novel drug targets for acute phase of TLE, and treatment options targeting these proteins could be beneficial in successfully managing acute epilepsy. Further evaluation of 6-BIO to explore its therapeutic potential in other models of epilepsy should be conducted.

GSK3β phosphorylates Six1 transcription factor and regulates its APC/CCdh1 mediated proteosomal degradation

Sine oculis homeobox homolog 1 (Six1) is a developmentally important transcription factor that regulates cellular proliferation, apoptosis, and dissemination during embryogenesis. Six1 overexpression as reported in multiple cancers modulates expression of a repertoire of its target genes causing an increase in proliferation, metastasis and survival of cancer cells. Six1 exists as a cell cycle regulated nuclear phosphoprotein and its cellular turnover is regulated by APC/C (Anaphase promoting complex / Cyclosome) complex mediated proteolysis. However, the kinases that regulate Six1 proteolysis have not been identified and the mechanistic details that cause its overproduction in various cancers are lacking. Here, we report that Six1 is a physiological GSK3β substrate. GSK3β interacts with Six1 and phosphorylates it at Ser221 within the conserved consensus sequence in its carboxy terminus. Using pharmacological inhibition, siRNA mediated knockdown and protein overexpression of GSK3β; we show that GSK3β regulates Six1 protein stability. Pulse chase analysis of Six1 revealed that GSK3β regulates its ubiquitin proteolysis such that Six1 phosphomimicking mutant (Six1S221E) for Ser221 site had dramatically increased half-life than its phosphodeficient (Six1S221A) and wild type variants. Furthermore, we demonstrate that GSK3β rescues Six1 from APC dependent proteolysis by regulating its binding with APC/C co-activator protein Cdh1. Importantly, strong positive correlation exists between GSK3β and Six1 protein levels throughout the cell cycle and in multiple cancers indicating that GSK3β activation may in part contribute to Six1 overproduction in a subset of human cancers.

Primary cilia promote the differentiation of human neurons through the WNT signaling pathway

BACKGROUND

Primary cilia emanate from most human cell types, including neurons. Cilia are important for communicating with the cell's immediate environment: signal reception and transduction to/from the ciliated cell. Deregulation of ciliary signaling can lead to ciliopathies and certain neurodevelopmental disorders. In the developing brain cilia play well-documented roles for the expansion of the neural progenitor cell pool, while information about the roles of cilia during post-mitotic neuron differentiation and maturation is scarce.

RESULTS

We employed ciliated Lund Human Mesencephalic (LUHMES) cells in time course experiments to assess the impact of ciliary signaling on neuron differentiation. By comparing ciliated and non-ciliated neuronal precursor cells and neurons in wild type and in RFX2 -/- mutant neurons with altered cilia, we discovered an early-differentiation "ciliary time window" during which transient cilia promote axon outgrowth, branching and arborization. Experiments in neurons with IFT88 and IFT172 ciliary gene knockdowns, leading to shorter cilia, confirm these results. Cilia promote neuron differentiation by tipping WNT signaling toward the non-canonical pathway, in turn activating WNT pathway output genes implicated in cyto-architectural changes.

CONCLUSIONS

We provide a mechanistic entry point into when and how ciliary signaling coordinates, promotes and translates into anatomical changes. We hypothesize that ciliary alterations causing neuron differentiation defects may result in "mild" impairments of brain development, possibly underpinning certain aspects of neurodevelopmental disorders.

Cardiomyocyte Differentiation from Mouse Embryonic Stem Cells by WNT Switch Method

The differentiation of ESCs into cardiomyocytes in vitro is an excellent and reliable model system for studying normal cardiomyocyte development in mammals, modeling cardiac diseases, and for use in drug screening. Mouse ESC differentiation still provides relevant biological information about cardiac development. However, the current methods for efficiently differentiating ESCs into cardiomyocytes are limiting. Here, we describe the "WNT Switch" method to efficiently commit mouse ESCs into cardiomyocytes using the small molecule WNT signaling modulators CHIR99021 and XAV939 in vitro. This method significantly improves the yield of beating cardiomyocytes, reduces number of treatments, and is less laborious.

Ischemia-reperfusion injury: molecular mechanisms and therapeutic targets

Ischemia-reperfusion (I/R) injury paradoxically occurs during reperfusion following ischemia, exacerbating the initial tissue damage. The limited understanding of the intricate mechanisms underlying I/R injury hinders the development of effective therapeutic interventions. The Wnt signaling pathway exhibits extensive crosstalk with various other pathways, forming a network system of signaling pathways involved in I/R injury. This review article elucidates the underlying mechanisms involved in Wnt signaling, as well as the complex interplay between Wnt and other pathways, including Notch, phosphatidylinositol 3-kinase/protein kinase B, transforming growth factor-β, nuclear factor kappa, bone morphogenetic protein, N-methyl-D-aspartic acid receptor-Ca2+-Activin A, Hippo-Yes-associated protein, toll-like receptor 4/toll-interleukine-1 receptor domain-containing adapter-inducing interferon-β, and hepatocyte growth factor/mesenchymal-epithelial transition factor. In particular, we delve into their respective contributions to key pathological processes, including apoptosis, the inflammatory response, oxidative stress, extracellular matrix remodeling, angiogenesis, cell hypertrophy, fibrosis, ferroptosis, neurogenesis, and blood-brain barrier damage during I/R injury. Our comprehensive analysis of the mechanisms involved in Wnt signaling during I/R reveals that activation of the canonical Wnt pathway promotes organ recovery, while activation of the non-canonical Wnt pathways exacerbates injury. Moreover, we explore novel therapeutic approaches based on these mechanistic findings, incorporating evidence from animal experiments, current standards, and clinical trials. The objective of this review is to provide deeper insights into the roles of Wnt and its crosstalk signaling pathways in I/R-mediated processes and organ dysfunction, to facilitate the development of innovative therapeutic agents for I/R injury.

Wnt/beta-catenin signaling and its modulators in nonalcoholic fatty liver diseases

Nonalcoholic fatty liver disease (NAFLD) is a global health concern associated with significant morbidity and mortality. NAFLD is a spectrum of diseases originating from simple steatosis, progressing through nonalcoholic steatohepatitis (NASH), fibrosis, and cirrhosis that may lead to hepatocellular carcinoma (HCC). The pathogenesis of NAFLD is mediated by the triglyceride accumulation followed by proinflammatory cytokines expression leading to inflammation, oxidative stress, and mitochondrial dysfunction denoted as "two-hit hypothesis", advancing with a "third hit" of insufficient hepatocyte proliferation, leading to the increase in hepatic progenitor cells contributing to fibrosis and HCC. Wnt/β-catenin signaling is responsible for normal liver development, regeneration, hepatic metabolic zonation, ammonia and drug detoxification, hepatobiliary development, etc., maintaining the overall liver homeostasis. The key regulators of canonical Wnt signaling such as LRP6, Wnt1, Wnt3a, β-catenin, GSK-3β, and APC are abnormally regulated in NAFLD. Many experimental studies have shown the aberrated Wnt/β-catenin signaling during the NAFLD progression and NASH to hepatic fibrosis and HCC. Therefore, in this review, we have emphasized the role of Wnt/β-catenin signaling and its modulators that can potentially aid in the inhibition of NAFLD.

Mutant APC reshapes Wnt signaling plasma membrane nanodomains by altering cholesterol levels via oncogenic β-catenin

Although the role of the Wnt pathway in colon carcinogenesis has been described previously, it has been recently demonstrated that Wnt signaling originates from highly dynamic nano-assemblies at the plasma membrane. However, little is known regarding the role of oncogenic APC in reshaping Wnt nanodomains. This is noteworthy, because oncogenic APC does not act autonomously and requires activation of Wnt effectors upstream of APC to drive aberrant Wnt signaling. Here, we demonstrate the role of oncogenic APC in increasing plasma membrane free cholesterol and rigidity, thereby modulating Wnt signaling hubs. This results in an overactivation of Wnt signaling in the colon. Finally, using the Drosophila sterol auxotroph model, we demonstrate the unique ability of exogenous free cholesterol to disrupt plasma membrane homeostasis and drive Wnt signaling in a wildtype APC background. Collectively, these findings provide a link between oncogenic APC, loss of plasma membrane homeostasis and CRC development.

Resveratrol induces the growth inhibition of CDX-deficient gastric cancer cells using CDX2 and RUNX3 via the β-catenin/TCF4 signaling pathway

This study aimed to determine the expression levels of runt-related transcription factor 3 (RUNX3) and caudal-related homeobox 2 (CDX2) in patients with chronic gastritis, intestinal metaplasia, atypical hyperplasia, and gastric cancer (GC). To analyze the overexpression of CDX2 and the effects of resveratrol (Res) on MKN7 and TMK1 cells, immunohistochemical staining was performed to determine the protein expression levels in tissue samples. The biological activity of MKN7 and TMK1 cells was determined. Relative mRNA and protein expression levels were also determined. RUNX3 expression was positively correlated with CDX2 expression and negatively correlated with β-catenin and transcription factor 4 (TCF-4) levels in GC tissues. Interestingly, RUNX3 expression was negatively correlated with CDX2 expression in other tissues. CDX2 overexpression or Res treatment inhibited cell proliferation, migration, and invasion, while inducing cell apoptosis. Furthermore, RUNX3 and B-cell lymphoma-2 (Bcl-2)-associated X protein (Bax) expression levels were increased, while those of of β-catenin, TCF-4, and Bcl-2 were decreased in the CDX2 group. Upon treatment with lithium chloride (LiCl), the proliferation, migration, and invasion of CDX2-overexpressing MKN7 and TMK1 cells were enhanced. Our results indicate that Res inhibits the growth of MKN7 and TMK1 cells by increasing RUNX3 and CDX2 expression levels, with the potential involvement of the β-catenin/TCF-4 signaling pathway.

Machine perfusion of the liver and bioengineering

With the increasing number of accepted candidates on waiting lists worldwide, there is an urgent need to expand the number and the quality of donor livers. Dynamic preservation approaches have demonstrated various benefits, including improving liver function and graft survival, and reducing liver injury and post-transplant complications. Consequently, organ perfusion techniques are being used in clinical practice in many countries. Despite this success, a proportion of livers do not meet current viability tests required for transplantation, even with the use of modern perfusion techniques. Therefore, devices are needed to further optimise machine liver perfusion - one promising option is to prolong machine liver perfusion for several days, with ex situ treatment of perfused livers. For example, stem cells, senolytics, or molecules targeting mitochondria or downstream signalling can be administered during long-term liver perfusion to modulate repair mechanisms and regeneration. Besides, today's perfusion equipment is also designed to enable the use of various liver bioengineering techniques, to develop scaffolds or for their re-cellularisation. Cells or entire livers can also undergo gene modulation to modify animal livers for xenotransplantation, to directly treat injured organs or to repopulate such scaffolds with "repaired" autologous cells. This review first discusses current strategies to improve the quality of donor livers, and secondly reports on bioengineering techniques to design optimised organs during machine perfusion. Current practice, as well as the benefits and challenges associated with these different perfusion strategies are discussed.

Dexamethasone Modulates the Dynamics of Wnt Signaling in Human Trabecular Meshwork Cells

Trabecular meshwork (TM) tissue is highly specialized, and its structural integrity is crucial for maintaining homeostatic intraocular pressure (IOP). The administration of glucocorticoids, such as dexamethasone (DEX), can perturb the TM structure and significantly increase IOP in susceptible individuals, resulting in ocular diseases such as steroid-induced glaucoma, a form of open-angle glaucoma. Although the exact mechanism involved in steroid-induced glaucoma remains elusive, increasing evidence suggests that DEX may act through various signaling cascades in TM cells. Despite uncertainty surrounding the specific process by which steroid-induced glaucoma occurs, there is growing evidence to indicate that DEX can impact multiple signaling pathways within TM cells. In this study, we examined the impact of DEX treatment on the Wnt signaling pathway in TM cells, given that Wnt signaling has been reported to play a crucial role in regulating extracellular matrix (ECM) levels in the TM. To further elucidate the role of Wnt signaling in the glaucomatous phenotype, we examined mRNA expression patterns between Wnt signaling markers AXIN2 and sFRP1 and DEX-mediated induction of myocilin (MYOC) mRNA and protein levels over 10 days in DEX-treated primary TM cells. We observed a sequential pattern of peak expression between AXIN2, sFRP1, and MYOC. Based on the study, we propose that sFRP1 upregulation could be a result of a negative feedback mechanism generated by stressed TM cells to suppress abnormal Wnt signaling activities.

Definitive Endodermal Cells Supply an in vitro Source of Mesenchymal Stem/Stromal Cells

Mesenchymal stem/Stromal cells (MSCs) have great therapeutic potentials, and they have been isolated from various tissues and organs including definitive endoderm (DE) organs, such as the lung, liver and intestine. MSCs have been induced from human pluripotent stem cells (hPSCs) through multiple embryonic lineages, including the mesoderm, neural crest, and extraembryonic cells. However, it remains unclear whether hPSCs could give rise to MSCs in vitro through the endodermal lineage. Here, we report that hPSC-derived, SOX17⁺ definitive endoderm progenitors can further differentiate to cells expressing classic MSC markers, which we name definitive endoderm-derived MSCs (DE-MSCs). Single cell RNA sequencing demonstrates the stepwise emergence of DE-MSCs, while endoderm-specific gene expression can be elevated by signaling modulation. DE-MSCs display multipotency and immunomodulatory activity in vitro and possess therapeutic effects in a mouse ulcerative colitis model. This study reveals that, in addition to the other germ layers, the definitive endoderm can also contribute to MSCs and DE-MSCs could be a cell source for regenerative medicine.

Wnt Signaling Inhibitors and Their Promising Role in Tumor Treatment

In a continuous search for the improvement of antitumor therapies, the inhibition of the Wnt signaling pathway has been recognized as a promising target. The altered functioning of the Wnt signaling in human tumors points to the strategy of the inhibition of its activity that would impact the clinical outcomes and survival of patients. Because the Wnt pathway is often mutated or epigenetically altered in tumors, which promotes its activation, inhibitors of Wnt signaling are being intensively investigated. It has been shown that knocking down specific components of the Wnt pathway has inhibitory effects on tumor growth in vivo and in vitro. Thus, similar effects are expected from the application of Wnt inhibitors. In the last decades, molecules acting as inhibitors on the pathway’s specific molecular levels have been identified and characterized. This review will discuss the inhibitors of the canonical Wnt pathway, summarize knowledge on their effectiveness as therapeutics, and debate their side effects. The role of the components frequently mutated in various tumors that are principal targets for Wnt inhibitors is also going to be brought to the reader’s attention. Some of the molecules identified as Wnt pathway inhibitors have reached early stages of clinical trials, and some have only just been discovered. All things considered, inhibition of the Wnt signaling pathway shows potential for the development of future therapies.

Nogo-B deficiency suppresses white adipogenesis by regulating β-catenin signaling

AIMS

Obesity is a global epidemic around the world. Reticulon-4B (Nogo-B) is an endoplasmic reticulum-resident protein. Our previous work demonstrated that Nogo-B deficiency inhibited obesity and decreased the size of white adipocytes. However, the underlying molecular mechanism of Nogo-B in white adipogenesis remains poorly understood. This study aims to explore the effect of Nogo-B in white adipogenesis, as well as its underlying molecular mechanisms.

MAIN METHODS AND FINDINGS

The study adopted mouse embryonic fibroblasts (MEFs) and 3T3-L1 preadipocytes to induce white adipogenesis and investigate the effect of Nogo-B on adipogenesis using qRT-PCR, Western blotting, immunofluorescence, lipid quantification, and Oil Red O staining. During white adipogenesis, Nogo-B expression was increased accompanied by upregulation of adipogenic markers. In contrast, Nogo-B deficiency inhibited white adipocyte markers expression and lipid accumulation. Furthermore, the mechanism study showed that Nogo-B deficiency decreased the destruction complex [AXIN1-APC-glycogen synthase kinase 3β (GSK3β)] levels through activating protein kinase B 2 (AKT2), resulting in β-catenin translocating into the nucleus and inhibiting the expression of adipogenic markers. Moreover, Nogo-B deficiency promoted the expression of brown/beige adipocytes markers while improving mitochondrial thermogenesis by activating β-catenin pathway. In addition, Nogo-B deficiency reduced the levels of inflammatory molecules during white adipogenic differentiation.

SIGNIFICANCE

This study revealed that Nogo-B deficiency inhibited white adipogenesis through AKT2/GSK3β/β-catenin pathway. Meanwhile, Nogo-B deficiency increased the expression of brown/beige adipocyte markers and promoted mitochondrial thermogenesis. In addition, Nogo-B deficiency reduced inflammatory cytokine levels caused by adipogenesis. Collectively, blocking Nogo-B expression may be a potential strategy to suppress white adipogenesis.

Novel splice variants of LINC00963 suppress colorectal cancer cell proliferation via miR-10a/miR-143/miR-217/miR-512-mediated regulation of PI3K/AKT and Wnt/β-catenin signaling pathways

Emerging evidence has shown lncRNAs play important roles in signaling pathways involved in colorectal cancer (CRC) carcinogenesis. However, only a few functional lncRNAs have been extensively researched, especially in CRC-related signaling pathways. Looking for novel candidate regulators of CRC incidence and progression, using available RNA-seq and microarray datasets, LINC00963 was introduced as a bona fide oncogenic-lncRNA. Consistently, RT-qPCR results showed that LINC00963 was up-regulated in CRC tissues. However, our attempt to amplify the full-length lncRNA from cDNA resulted in the discovery of two novel variants (LINC00963-v2 & LINC00963-v3) that surprisingly, were downregulated in CRC tissues, detected by RT-qPCR. Overexpression of LINC00963-v2/-v3 in HCT116 and SW480 cells resulted in downregulation of the major oncogenes and upregulation of the main tumor suppressor genes involved in PI3K and Wnt signaling, verified through RT-qPCR, western blotting, and TOPFlash assays. Mechanistic studies revealed that LINC00963-v2/-v3 exert their effect on PI3K and Wnt signaling through sponging miR-10a-5p, miR-143-3p, miR-217, and miR-512-3p, which in turn these miRNAs are fine-regulators of PTEN, APC1, and Axin1 tumor suppressor genes verified by dual-luciferase assay and RT-qPCR. At cellular levels, LINC00963-v2/-v3 overexpression suppressed cell proliferation, viability, and migration while increasing the apoptosis of CRC cell lines, detected by PI flow cytometry, colony formation, MTT, RT-qPCR, wound-healing, Transwell, AnnexinV-PE/7AAD, caspase3/7 activity assays, and Hoechst/PI-AO/EB staining. Overall, our results indicate that LINC00963-v2 & -v3 are novel tumor suppressor ceRNAs that attenuate the PI3K and Wnt pathways during CRC incidence and these lncRNAs may serve as potential targets for CRC therapy.

Feedback in the β-catenin destruction complex imparts bistability and cellular memory

Wnt ligands are considered classical morphogens, for which the strength of the cellular response is proportional to the concentration of the ligand. Herein, we show an emergent property of bistability arising from feedback among the Wnt destruction complex proteins that target the key transcriptional co-activator β-catenin for degradation. Using biochemical reconstitution, we identified positive feedback between the scaffold protein Axin and the kinase glycogen synthase kinase 3 (GSK3). Theoretical modeling of this feedback between Axin and GSK3 suggested that the activity of the destruction complex exhibits bistable behavior. We experimentally confirmed these predictions by demonstrating that cellular cytoplasmic β-catenin concentrations exhibit an "all-or-none" response with sustained memory (hysteresis) of the signaling input. This bistable behavior was transformed into a graded response and memory was lost through inhibition of GSK3. These findings provide a mechanism for establishing decisive, switch-like cellular response and memory upon Wnt pathway stimulation.

Proteome changes of sheep rumen epithelium during postnatal development

Background: The development of the rumen epithelium is a critical physiological challenge for sheep. However, the molecular mechanism underlying postnatal rumen development in sheep remains rarely understood.

Results: Here, we used a shotgun approach and bioinformatics analyses to investigate and compare proteomic profiles of sheep rumen epithelium tissue on day 0, 15, 30, 45, and 60 of age. A total of 4,523 proteins were identified, in which we found 852, 342, 164, and 95 differentially expressed proteins (DEPs) between day 0 and day 15, between day 15 and day 30, between day 30 and day 45, between day 45 and day 60, respectively. Furthermore, subcellular localization analysis showed that the DEPs were majorly localized in mitochondrion between day 0 and day 15, after which nucleus proteins were the most DEPs. Finally, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses showed that DEPs significantly enriched in mitochondrion, ubiquitination, histone modifications, glutathione synthase activity, and wnt and nortch signaling pathways.

Conclusion: Our data indicate that the biogenesis of mitochondrion in rumen epithelial cell is essential for the initiation of rumen epithelial development. Glutathione, wnt signaling pathway and nortch signaling pathway participated in rumen epithelial growth. Ubiquitination, post-translational modifications of histone might be key molecular functions in regulating rumen epithelial development.

Targeting lncRNA/Wnt axis by flavonoids: A promising therapeutic approach for colorectal cancer

Despite the dramatic advances in our understanding of the etiology of colorectal cancer (CRC) in recent decades, effective therapeutic strategies are still urgently needed. Oncogenic mutations in the Wnt/β-Catenin pathway are hallmarks of CRC. Moreover, long non-coding RNAs (lncRNAs) as molecular managers are involved in the initiation, progression, and metastasis of CRC. Therefore, it is important to further explore the interaction between lncRNAs and Wnt/β-Catenin signaling pathway for targeted therapy of CRC. Natural phytochemicals have not toxicity and can target carcinogenesis-related pathways. Growing evidences suggest that flavonoids are inversely associated with CRC risk. These bioactive compounds could target carcinogenesis pathways of CRC and reduced the side effects of anti-cancer drugs. The review systematically summarized the progress of flavonoids targeting lncRNA/Wnt axis in the investigations of CRC, which will provide a promising therapeutic approach for CRC and develop nutrition-oriented preventive strategies for CRC based on epigenetic mechanisms. In the field, more epidemiological and clinical trials are required in the future to verify feasibility of targeting lncRNA/Wnt axis by flavonoids in the therapy and prevention of CRC.

Nuclear Dishevelled: An enigmatic role in governing cell fate and Wnt signaling

The Dishevelled gene was first identified in Drosophila mutants with disoriented hair and bristle polarity and subsequent work has now demonstrated its importance in critical and diverse aspects of biology. Since those early discoveries, Dishevelled has been shown to coordinate a plethora of developmental and cellular processes that range from controlling cell polarity during gastrulation to partnering with chromatin modifying enzymes to regulate histone methylation at genomic loci. While the role of DVL in development is well-respected and the cytosolic function of DVL has been studied more extensively, its nuclear role continues to remain murky. In this review we highlight some of the seminal discoveries that have contributed to the field, but the primary focus is to discuss recent advances with respect to the nuclear role of Dishevelled. This nuclear function of Dishevelled is a dimension which is proving to be increasingly important yet remains enigmatic.

Mural Wnt/β-catenin signaling regulates Lama2 expression to promote neurovascular unit maturation

Neurovascular unit and barrier maturation rely on vascular basement membrane (vBM) composition. Laminins, a major vBM component, are crucial for these processes, yet the signaling pathway(s) that regulate their expression remain unknown. Here, we show that mural cells have active Wnt/β-catenin signaling during central nervous system development in mice. Bulk RNA sequencing and validation using postnatal day 10 and 14 wild-type versus adenomatosis polyposis coli downregulated 1 (Apcdd1-/-) mouse retinas revealed that Lama2 mRNA and protein levels are increased in mutant vasculature with higher Wnt/β-catenin signaling. Mural cells are the main source of Lama2, and Wnt/β-catenin activation induces Lama2 expression in mural cells in vitro. Markers of mature astrocytes, including aquaporin 4 (a water channel in astrocyte endfeet) and integrin-α6 (a laminin receptor), are upregulated in Apcdd1-/- retinas with higher Lama2 vBM deposition. Thus, the Wnt/β-catenin pathway regulates Lama2 expression in mural cells to promote neurovascular unit and barrier maturation.

Fluorescent probes and functional materials for biomedical applications

Due to their simplicity in preparation, sensitivity and selectivity, fluorescent probes have become the analytical tool of choice in a wide range of research and industrial fields, facilitating the rapid detection of chemical substances of interest as well as the study of important physiological and pathological processes at the cellular level. In addition, many long-wavelength fluorescent probes developed have also proven applicable for in vivo biomedical applications including fluorescence-guided disease diagnosis and theranostics (e.g., fluorogenic prodrugs). Impressive progresses have been made in the development of sensing agents and materials for the detection of ions, organic small molecules, and biomacromolecules including enzymes, DNAs/RNAs, lipids, and carbohydrates that play crucial roles in biological and disease-relevant events. Here, we highlight examples of fluorescent probes and functional materials for biological applications selected from the special issues “Fluorescent Probes” and “Molecular Sensors and Logic Gates” recently published in this journal, offering insights into the future development of powerful fluorescence-based chemical tools for basic biological studies and clinical translation.

Premise and peril of Wnt signaling activation through GSK-3β inhibition

Wnt signaling pathways have been extensively studied in the context of several diseases, including cancer, coronary artery disease, and age-related disorders. β-Catenin plays a central role in the most studied Wnt pathways, the Wnt/β-catenin signaling pathway, commonly referred to as the canonical Wnt signaling pathway. β-catenin is a substrate of glycogen synthase kinase 3β (GSK-3β), and the phosphorylated β-catenin by GSK-3β can be degraded by the proteasome through ubiquitination. Thus, GSK-3β inhibitors have become a widely used chemical biology tool to study the canonical Wnt signaling pathway. Among the varied GSK-3β inhibitors, a compound known as CHIR-99021 is one of the most widely used. Although these inhibitors contribute greatly to our understanding of the canonical Wnt pathway, certain pitfalls associated with such an approach may have been overlooked. In many published studies, micromolar concentrations of CHIR-99021 are used to activate the canonical Wnt pathway. Although CHIR-99021 is a specific GSK-3β inhibitor, it specifically inhibits the kinase at the nanomolar level. Therefore, caution is required when micromolar levels of CHIR-99021 are used for the purpose of activating the canonical Wnt signaling pathway.

Approaches for Regenerative Healing of Cutaneous Wound with an Emphasis on Strategies Activating the Wnt/β-Catenin Pathway

Significance: In adult mammals, spontaneous repair of a cutaneous wound occurs slowly and leaves a scar with skin adnexa deficiencies. To accelerate cutaneous wound-healing rates and avoid scar formation, current studies have focused on regenerative therapies. Recent Advances: Emerging therapeutics for regenerative wound healing often focus on the use of growth factors and stem cells. However, these therapeutic approaches have limited routine clinical use due to high costs and technical requirements. Critical Issue: Understanding the molecular mechanisms involved in the signaling pathways for cutaneous wound healing and neogenic synthesis of the skin components is important for identification of novel targets for the development of regenerative wound-healing agents. Future Directions: The Wnt/β-catenin pathway is a well-known key player for enhancement of the overall healing process involving tissue regeneration via crosstalk with other signaling pathways. Strategies that activate the Wnt/β-catenin pathway via modulation of the pathway-controlling regulatory factors could provide effective therapeutic approaches for regenerative wound healing.

The functional role of Pescadillo ribosomal biogenesis factor 1 in cancer

Tumors are neogrowths formed by the growth of normal cells or tissues through complex mechanisms under the influence of many factors. The occurrence and development of tumors are affected by many factors. Pescadillo ribosomal biogenesis factor 1 (PES1) has been identified as a cancer-related gene. The study of these genes may open up new avenues for early diagnosis, treatment and prognosis of tumors. As a nucleolar protein and part of the Pes1/Bop1/WDR12 (PeBoW) complex, PES1 is involved in ribosome biogenesis and DNA replication. Many studies have shown that high expression of PES1 is often closely related to the occurrence, proliferation, invasion, metastasis, prognosis and sensitivity to chemotherapeutics of various human malignant tumors through a series of molecular mechanisms and signaling pathways. The molecules that regulate the expression of PES1 include microRNA (miRNA), circular RNA (circRNA), c-Jun, bromodomain-containing protein 4 (BRD4) and nucleolar phosphoprotein B23. However, the detailed pathogenic mechanisms of PES1 overexpression in human malignancies remains unclear. This article summarizes the role of PES1 in the carcinogenesis, prognosis and treatment of multiple tumors, and introduces the molecular mechanisms and signal transduction pathways related to PES1.

Generation of In Vivo Traceable Hepatocyte-Like Cells from Human iPSCs

In this chapter, we describe a protocol for differentiation of human-induced pluripotent stem cells (iPSCs) into hepatocyte-like cells (HLCs) and their transduction with a lentivirus for gene transfer. Here, we engineer them to express the human sodium iodide symporter, which can be exploited as a radionuclide reporter gene, thereby enabling these cells to be tracked in vivo by single-photon emission computed tomography (SPECT) or positron emission tomography (PET) imaging. Differentiation of HLCs from iPSCs involves three steps: induction of iPSCs to definitive endoderm, differentiation to a hepatic progenitor cell population, and maturation of immature HLCs. Once proliferation of hepatic progenitors has ceased and an immature HLC population is generated, lentiviral transduction can be performed. The immature hepatic gene expression profile/morphology at the stage of transduction will be compatible with further maturation following transgene expression either in vitro or in vivo, with expression of the transgene retained. We detail how transgenic cells can be imaged in vivo. While we provide a protocol for the NIS reporter gene, the cell engineering aspects of this protocol are transferable for use with other (reporter) genes if desired.

Systems for Muscle Cell Differentiation: From Bioengineering to Future Food

In light of pressing issues, such as sustainability and climate change, future protein sources will increasingly turn from livestock to cell-based production and manufacturing activities. In the case of cell-based or cultured meat a relevant aspect would be the differentiation of muscle cells into mature muscle tissue, as well as how the microsystems that have been developed to date can be developed for larger-scale cultures. To delve into this aspect we review previous research that has been carried out on skeletal muscle tissue engineering and how various biological and physicochemical factors, mechanical and electrical stimuli, affect muscle cell differentiation on an experimental scale. Material aspects such as the different biomaterials used and 3D vs. 2D configurations in the context of muscle cell differentiation will also be discussed. Finally, the ability to translate these systems to more scalable bioreactor configurations and eventually bring them to a commercial scale will be touched upon.

Plant-Derived Chinese Medicine Monomers on Ovarian Cancer via the Wnt/β-Catenin Signaling Pathway: Review of Mechanisms and Prospects

Ovarian cancer (OC) is a common malignant tumor of the female reproductive system and has a high morbidity and mortality rate. The progression and metastasis of OC are complex and involve multiple signaling pathways. The Wnt/β-catenin signaling pathway is closely related to OC, and therefore blocking the activation of the Wnt/β-catenin signaling directly or inhibiting related genes, and molecular targets is of great value in treating OC. Toxicities such as myelotoxicity, cardiotoxicity, genotoxicity, and vasospasm are the major side effects for common anticancer drugs and are well documented. There is, therefore, a need to develop new, effective, safer, and more affordable anticancer drugs from alternative sources. In recent years, plant-derived Chinese medicine monomers have drawn increasing attention due to their high safety, low toxicity, minimal side effects, and antitumor effects. Plant-derived Chinese medicine monomers are effective against multiple targets and can regulate the growth, proliferation, apoptosis, invasion, and migration of OC as well as reverse drug resistance by regulating the Wnt/β-catenin signaling pathway. In this review, we summarize and provide mechanisms and prospects for the use of plant-derived Chinese medicines for the prevention and treatment of OC.

Role of Wnt signaling in synaptic plasticity and memory

Ever since their discoveries, the Wnt pathways have been consistently associated with key features of cellular development, including metabolism, structure and cell fate. The three known pathways (the canonical Wnt/β-catenin and the two non-canonical Wnt/Ca⁺⁺ and Wnt/JNK/PCP pathways) participate in complex networks of interaction with a wide range of regulators of cell function, such as GSK-3β, AKT, PKC and mTOR, among others. These proteins are known to be involved in the formation and maintenance of memory. Currently, studies with Wnt and memory have shown that the canonical and non-canonical pathways play key roles in different processes associated with memory. So, in this review we briefly summarize the different roles that Wnt signaling can play in neurons and in memory, as well as in Alzheimer's disease, focusing towards animal studies. We start with the molecular characterization of the family and its receptors, as well as the most commonly used drugs for pharmacological manipulations. Next, we describe its role in synaptic plasticity and memory, and how the regulations of these pathways affect crucial features of neuronal function. Furthermore, we succinctly present the current knowledge on how the Wnt pathways are implicated in Alzheimer's disease, and how studies are seeing them as a potential candidate for effective treatments. Lastly, we point toward challenges of Wnt research, and how knowledge on these pathways can lead towards a better understanding of neurobiological and pathological processes.

Drug discovery efforts toward inhibitors of canonical Wnt/β-catenin signaling pathway in the treatment of cancer: A composition-of-matter review (2010-2020)

The Wnt/β-catenin pathway has a crucial role in the proliferation and differentiation of normal cells as well as the self-renewal and pluripotency of stem cells, including cancer stem cells (CSCs). Targeting this pathway with small-molecule chemotherapeutics, discovered via conventional efforts, has proved difficult. Recently, computer-aided drug discovery efforts have produced promising chemotherapeutics. A concerted effort to develop inhibitors of this pathway through more efficient and cost-effective drug discovery methods could lead to a significant increase in clinically relevant therapeutics. Herein, patents from 2010 to 2020 are reviewed to identify those that have disclosed composition of matter for small-molecule inhibitors of the Wnt/ β-catenin pathway for cancer. We believe that such efforts will provide insights for future therapeutic candidate discovery and development in this field.

Human limbal epithelial stem cell regulation, bioengineering and function

The corneal epithelium is continuously renewed by limbal stem/progenitor cells (LSCs), a cell population harbored in a highly regulated niche located at the limbus. Dysfunction and/or loss of LSCs and their niche cause limbal stem cell deficiency (LSCD), a disease that is marked by invasion of conjunctival epithelium into the cornea and results in failure of epithelial wound healing. Corneal opacity, pain, loss of vision, and blindness are the consequences of LSCD. Successful treatment of LSCD depends on accurate diagnosis and staging of the disease and requires restoration of functional LSCs and their niche. This review highlights the major advances in the identification of potential LSC biomarkers and components of the LSC niche, understanding of LSC regulation, methods and regulatory standards in bioengineering of LSCs, and diagnosis and staging of LSCD. Overall, this review presents key points for researchers and clinicians alike to consider in deepening the understanding of LSC biology and improving LSCD therapies.

Activation of adult mammalian retinal stem cells in vivo via antagonism of BMP and sFRP2

Background

The adult mammalian retina does not have the capacity to regenerate cells lost due to damage or disease. Therefore, retinal injuries and blinding diseases result in irreversible vision loss. However, retinal stem cells (RSCs), which participate in retinogenesis during development, persist in a quiescent state in the ciliary epithelium (CE) of the adult mammalian eye. Moreover, RSCs retain the ability to generate all retinal cell types when cultured in vitro, including photoreceptors. Therefore, it may be possible to activate endogenous RSCs to induce retinal neurogenesis in vivo and restore vision in the adult mammalian eye.

Methods

To investigate if endogenous RSCs can be activated, we performed combinatorial intravitreal injections of antagonists to BMP and sFRP2 proteins (two proposed mediators of RSC quiescence in vivo), with or without growth factors FGF and Insulin. We also investigated the effects of chemically-induced N-methyl-N-Nitrosourea (MNU) retinal degeneration on RSC activation, both alone and in combination withthe injected factors. Further, we employed inducible Msx1-Cre^ERT2 genetic lineage labeling of the CE followed by stimulation paradigms to determine if activated endogenous RSCs could migrate into the retina and differentiate into retinal neurons.

Results

We found that in vivo antagonism of BMP and sFRP2 proteins induced CE cells in the RSC niche to proliferate and expanded the RSC population. BMP and sFRP2 antagonism also enhanced CE cell proliferation in response to exogenous growth factor stimulation and MNU-induced retinal degeneration. Furthermore, Msx1-Cre^ERT2 genetic lineage tracing revealed that CE cells migrated into the retina following stimulation and/or injury, where they expressed markers of mature photoreceptors and retinal ganglion cells.

Conclusions

Together, these results indicate that endogenous adult mammalian RSCs may have latent regenerative potential that can be activated by modulating the RSC niche and hold promise as a means for endogenous retinal cell therapy to repair the retina and improve vision.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02630-0.

Differentiation of Human Pluripotent Stem Cells Into Specific Neural Lineages

Human pluripotent stem cells (hPSCs) are sources of several somatic cell types for human developmental studies, in vitro disease modeling, and cell transplantation therapy. Improving strategies of derivation of high-purity specific neural and glial lineages from hPSCs is critical for application to the study and therapy of the nervous system. Here, we will focus on the principles behind establishment of neuron and glia differentiation methods according to developmental studies. We will also highlight the limitations and challenges associated with the differentiation of several “difficult” neural lineages and delay in neuronal maturation and functional integration. To overcome these challenges, we will introduce strategies and novel technologies aimed at improving the differentiation of various neural lineages to expand the application potential of hPSCs to the study of the nervous system.

MiR-1224 Acts as a Prognostic Biomarker and Inhibits the Progression of Gastric Cancer by Targeting SATB1

Objective

MiR-1224 has been reported to exhibit abnormal expression in several tumors. However, the expressing pattern and roles of miR-1224 in gastric cancer (GC) remain unclear. Our current research aimed to explore the potential involvement of miR-1224 in the GC progression.

Materials and Methods

The expression of miR-1224 was examined in tissue samples of 128 GC patients and cell lines by RT-PCR. Besides, the associations of miR-1224 expressions with clinicopathologic features and prognosis of GC patients were analyzed. Then, the possible influences of miR-1224 on cell proliferation and cell migration were determined. Afterward, the molecular target of miR-1224 was identified using bioinformatics assays and confirmed experimentally. Finally, RT-PCR and Western blot assays were performed to investigate the effect of the abnormal miR-1224 expression on the EMT and Wnt/β-catenin pathway.

Results

miR-1224 was lowly expressed in the GC specimens and cell lines due to T classification and TNM stage. Survival assays demonstrated that GC patients with low expressions of miR-1224 possessed poor overall survivals. Moreover, in vitro and in vivo assays revealed that the overexpression of miR-1224 inhibited cell proliferation, migration, and invasion in GC cells. SATB homeobox 1 (SATB1) was verified as a direct target of miR-1224 in GC. Furthermore, β-catenin and c-myc were significantly inhibited in miR-1224-overexpression cells.

Conclusions

Our findings highlight the potential of miR-1224 as a therapeutic target and novel biomarker for GC patients

GSK3β as a novel promising target to overcome chemoresistance in pancreatic cancer

Pancreatic cancer is an aggressive malignancy with increasing incidence and poor prognosis due to its late diagnosis and intrinsic chemoresistance. Most pancreatic cancer patients present with locally advanced or metastatic disease characterized by inherent resistance to chemotherapy. These features pose a series of therapeutic challenges and new targets are urgently needed. Glycogen synthase kinase 3 beta (GSK3β) is a conserved serine/threonine kinase, which regulates key cellular processes including cell proliferation, DNA repair, cell cycle progression, signaling and metabolic pathways. GSK3β is implicated in non-malignant and malignant diseases including inflammation, neurodegenerative diseases, diabetes and cancer. GSK3β recently emerged among the key factors involved in the onset and progression of pancreatic cancer, as well as in the acquisition of chemoresistance. Intensive research has been conducted on key oncogenic functions of GSK3β and its potential as a druggable target; currently developed GSK3β inhibitors display promising results in preclinical models of distinct tumor types, including pancreatic cancer. Here, we review the latest findings about GSK-3β biology and its role in the development and progression of pancreatic cancer. Moreover, we discuss therapeutic agents targeting GSK3β that could be administered as monotherapy or in combination with other drugs to surmount chemoresistance. Several studies are also defining potential gene signatures to identify patients who might benefit from GSK3β-based therapeutic intervention. This detailed overview emphasizes the urgent need of additional molecular studies on the impact of GSK3β inhibition as well as structural analysis of novel compounds and omics studies of predictive biomarkers.

Morphological neurite changes induced by porcupine inhibition are rescued by Wnt ligands

Background

Wnt signaling plays key roles in cellular and physiological processes, including cell proliferation, differentiation and migration during development and tissue homeostasis in adults. This pathway can be defined as Wnt/β-catenin-dependent or β-catenin-independent or “non-canonical”, both signaling are involved in neurite and synapse development/maintenance. Porcupine (PORCN), an acylase that o-acylates Wnt ligands, a major modification in secretion and interaction with its receptors. We use Wnt-C59, a specific PORCN inhibitor, to block the secretion of endogenous Wnts in embryonic hippocampal neurons (DIV 4). Under these conditions, the activity of exogenous Wnt ligands on the complexity of the dendritic tree and axonal polarity were evaluated

Methods

Cultured primary embryonic hippocampal neurons obtained from Sprague–Dawley rat fetuses (E18), were cultured until day in vitro (DIV) 4 (according to Banker´s protocol) and treated with Wnt-C59 for 24 h, Wnt ligands were added to the cultures on DIV 3 for 24 h. Dendritic arbors and neurites were analysis by fluorescence microscopy. Transfection with Lipofectamine 2000 on DIV 2 of plasmid expressing eGFP and KIF5-Cherry was carried out to evaluate neuronal polarity. Immunostaining was performed with MAP1B and Tau protein. Immunoblot analysis was carried out with Wnt3a, β-catenin and GSK-3β (p-Ser9). Quantitative analysis of dendrite morphology was carried out with ImageJ (NIH) software with Neuron J Plugin.

Results

We report, here, that Wnt-C59 treatment changed the morphology of the dendritic arbors and neurites of embryonic hippocampal neurons, with decreases β-catenin and Wnt3a and an apparent increase in GSK-3β (p-Ser9) levels. No effect was observed on axonal polarity. In sister cultures, addition of exogenous Wnt3a, 5a and 7a ligands rescued the changes in neuronal morphology. Wnt3a restored the length of neurites to near that of the control, but Wnt7a increased the neurite length beyond that of the control. Wnt5a also restored the length of neurites relative to Wnt concentrations.

Conclusions

Results indicated that Wnt ligands, added exogenously, restored dendritic arbor complexity in embryonic hippocampal neurons, previously treated with a high affinity specific Porcupine inhibitor. We proposed that PORCN is an emerging molecular target of interest in the search for preclinical options to study and treat Wnt-related diseases.

Wnt signaling activation: targets and therapeutic opportunities for stem cell therapy and regenerative medicine

Wnt proteins are secreted morphogens that play critical roles in embryonic development, stem cell proliferation, self-renewal, tissue regeneration and remodeling in adults. While aberrant Wnt signaling contributes to diseases such as cancer, activation of Wnt/β-catenin signaling is a target of interest in stem cell therapy and regenerative medicine. Recent high throughput screenings from chemical and biological libraries, combined with improved gene expression reporter assays of Wnt/β-catenin activation together with rational drug design, led to the development of a myriad of Wnt activators, with different mechanisms of actions. Among them, Wnt mimics, antibodies targeting Wnt inhibitors, glycogen-synthase-3β inhibitors, and indirubins and other natural product derivatives are emerging modalities to treat bone, neurodegenerative, eye, and metabolic disorders, as well as prevent ageing. Nevertheless, the creation of Wnt-based therapies has been hampered by challenges in developing potent and selective Wnt activators without off-target effects, such as oncogenesis. On the other hand, to avoid these risks, their use to promote ex vivo expansion during tissue engineering is a promising application.

Cellular signaling crosstalk between Wnt signaling and gap junctions inbenzo[a]pyrene toxicity

Gap junctional intercellular communication (GJIC) is considered a key biological mechanism to maintain homeostasis in cell differentiation and growth. In addition, as another major signaling pathway associated with cell proliferation and differentiation, Wnt/β-catenin signaling appears to trigger several cellular responses against injury. The purpose of the present study was to investigate the effects of a known toxic agent, benzo[a]pyrene (BaP), on the regulation and interaction between GJIC and Wnt/β-catenin signaling. BaP treatment resulted in GJIC inhibition and decreases the major GJIC protein connexin 43 (Cx43) in WB-F344 rat liver epithelial cells. We also found BaP-mediated downregulation of Wnt/β-catenin signaling related to the PI3K-Akt pathway. To identify the relationship between GJIC and Wnt/β-catenin signaling, we treated WB-F344 cells with the Wnt agonist CHIR99021 and found that it inhibited GJIC while causing a significant reduction in Cx43 expression at both the mRNA and protein levels, through the repression of promoter activity. This Wnt agonist-mediated GJIC inhibition was confirmed using a small interfering RNA directed against the Wnt antagonist Dact2, indicating that Wnt/β-catenin signaling negatively regulates GJIC. Despite the inverse correlation between Wnt/β-catenin signaling and Cx43 promoter activation as indicated by downregulation of β-catenin nuclear translocation and upregulation of Cx43 promoter activation involving HNF3β, BaP treatment decreased the Cx43 protein expression, which was associated with protein degradation, possibly through protein kinase C activation. In conclusion, our results revealed the mechanism of BaP-induced inhibition of GJIC and Wnt/β-catenin signaling. More importantly, linking Wnt/β-catenin signaling to Cx protein expression will have profound implications in understanding the relationships among different major signaling pathways associated with cell proliferation and differentiation in toxicity.

Advances in targeting the WNT/β-catenin signaling pathway in cancer

WNT/β-catenin signaling orchestrates various physiological processes, including embryonic development, growth, tissue homeostasis, and regeneration. Abnormal WNT/β-catenin signaling is associated with various cancers and its inhibition has shown effective antitumor responses. In this review, we discuss the pathway, potential targets for the development of WNT/β-catenin inhibitors, available inhibitors, and their specific molecular interactions with the target proteins. We also discuss inhibitors that are in clinical trials and describe potential new avenues for therapeutically targeting the WNT/β-catenin pathway. Furthermore, we introduce emerging strategies, including artificial intelligence (AI)-assisted tools and technology-based actionable approaches, to translate WNT/β-catenin inhibitors to the clinic for cancer therapy.

PLEKHA4 Promotes Wnt/β-Catenin Signaling-Mediated G1-S Transition and Proliferation in Melanoma

Despite recent promising advances in targeted therapies and immunotherapies, patients with melanoma incur substantial mortality. In particular, inhibitors targeting BRAF-mutant melanoma can lead to resistance, and no targeted therapies exist for NRAS-mutant melanoma, motivating the search for additional therapeutic targets and vulnerable pathways. Here we identify a regulator of Wnt/β-catenin signaling, PLEKHA4, as a factor required for melanoma proliferation and survival. PLEKHA4 knockdown in vitro decreased Dishevelled levels, attenuated Wnt/β-catenin signaling, and blocked progression through the G1-S cell-cycle transition. In mouse xenograft and allograft models, inducible PLEKHA4 knockdown attenuated tumor growth in BRAF- and NRAS-mutant melanomas and exhibited an additive effect with the clinically used inhibitor encorafenib in a BRAF-mutant model. As an E3 ubiquitin ligase regulator with both lipid- and protein-binding partners, PLEKHA4 presents several opportunities for targeting with small molecules. Our work identifies PLEKHA4 as a promising drug target for melanoma and clarifies a controversial role for Wnt/β-catenin signaling in the control of melanoma proliferation. SIGNIFICANCE: This study establishes that melanoma cell proliferation requires the protein PLEKHA4 to promote pathologic Wnt signaling for proliferation, highlighting PLEKHA4 inhibition as a new avenue for the development of targeted therapies.

Recent advances in β-catenin/BCL9 protein-protein interaction inhibitors

Wnt/β-catenin signaling is crucial both in normal embryonic development and throughout the life of an organism. Moreover, aberrant Wnt signaling has been associated with various diseases, especially cancer and fibrosis. Recent research suggests that direct targeting of the β-catenin/BCL9 protein-protein interaction (PPI) is a promising strategy to block the Wnt pathway. Progress in understanding the cocrystalline complex and mechanism of action of the β-catenin/BCL9 interaction facilitates the discovery process of its inhibitors, but only a few inhibitors have been reported. In this review, the discovery and development of β-catenin/BCL9 PPI inhibitors in the areas of drug design, structure-activity relationships and biological and biochemical properties are summarized. In addition, perspectives for the future development of β-catenin/BCL9 PPI inhibitors are explored.

Cell signaling pathways as molecular targets to eliminate AML stem cells

Acute myeloid leukemia (AML) remains the most lethal of leukemias and a small population of cells called leukemic stem cells (LSCs) has been associated with disease relapses. Some cell signaling pathways play an important role in AML survival, proliferation and self-renewal properties and are abnormally activated or suppressed in LSCs. This includes the NF-κB, Wnt/β-catenin, Hedgehog, Notch, EGFR, JAK/STAT, PI3K/AKT/mTOR, TGF/SMAD and PPAR pathways. This review aimed to discuss these pathways as molecular targets for eliminating AML LSCs. Herein, inhibitors/activators of these pathways were summarized as a potential new anti-AML therapy capable of eliminating LSCs to guide future researches. The clinical use of cell signaling pathways data can be useful to enhance the anti-AML therapy.

Multi-omics characterization of WNT pathway reactivation to ameliorate BET inhibitor resistance in liver cancer cells

The Bromodomain and Extra-terminal domain (BET) proteins are promising targets in treating cancers. Although BET inhibitors have been in clinical trials, they are limited by lacking of suitable biomarkers to indicate drug responses in different cancers. Here we identify DHRS2, ETV4 and NOTUM as potential biomarkers to indicate drug resistance in liver cancer cells of a recently discovered BET inhibitor, Hjp-6-171. Furthermore, we confirm that reactivation of WNT pathway, the target of NOTUM, contributes to the drug sensitivity restoration in Hjp-6-171 resistant cells. Specially, combinations of Hjp-6-171 and a GSK3β inhibitor CHIR-98014 show remarkable therapeutic effects in vitro and in vivo. Integrating RNA-seq and ChIP-seq data, we reveal the expression signature of β-catenin regulated genes is contrary in sensitive cells to that in resistant cells. We propose WNT signaling molecules such as β-catenin and ETV4 to be candidate biomarkers to indicate BET inhibitor responses in liver cancer patients.

[Fractalkine inhibits lipopolysaccharide-induced M1 polarization of macrophages by activating Wnt/β-catenin signaling pathway]

OBJECTIVE

To explore the mechanism by which fractalkine (CX3CL1; FKN) inhibits lipopolysaccharide (LPS)-induced immunological response in RAW264.7 cells.

METHODS

A RAW264.7 cell model overexpressing FKN was established by transfection with the lentiviral vector CX3CL1. The effects of LPS, ICG-001 (a Wnt/β-catenin signaling pathway inhibitor), either alone or in combination, on M1 polarization of na?ve and FKN-overexpressing RAW264.7 cells were evaluated by detecting of intereukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) using ELISA. The protein expressions of the inflammatory factors (iNOS, TNF-α, and IL-6), FKN, Wnt-4, and β-catenin were detected by Western blotting. The subcellular localization of IL-6 in the cells was detected by immunofluorescence assay.

RESULTS

The RAW264.7 cell model of FKN overexpression was successfully established. In na?ve RAW264.7 cells, treatment with both ICG-001 and LPS, as compared with LPS alone, significant promoted TNF-α and IL-6 secretions, increased intracellular levels of TNF-α, IL-6 and iNOS (P < 0.05), and reduced intracellular FKN, Wnt-4 and β-catenin levels (P < 0.01). In FKN-overexpressing RAW264.7 cells, LPS treatment significantly reduced the secretion of TNF-α and IL-6 and intracellular levels of TNF-α, IL-6 and iNOS (P < 0.01), increased intracellular FKN, Wnt-4 and β-catenin protein contents (P < 0.01), and inhibited IL-6 localization in the cytoplasm; compared with LPS, the combined treatment with ICG-001 and LPS obviously enhanced IL-6 localization in the cytoplasm of the cells.

CONCLUSIONS

FKN overexpression suppresses LPS-induced M1 type polarization of RAW264.7 cells by activating Wnt/β-catenin signaling pathway.

Functional skeletal muscle constructs from transdifferentiated human fibroblasts

Transdifferentiation of human non-muscle cells directly into myogenic cells by forced expression of MyoD represents one route to obtain highly desirable human myogenic cells. However, functional properties of the tissue constructs derived from these transdifferentiated cells have been rarely studied. Here, we report that three-dimensional (3D) tissue constructs engineered with iMyoD-hTERT-NHDFs, normal human dermal fibroblasts transduced with genes encoding human telomerase reverse transcriptase and doxycycline-inducible MyoD, generate detectable contractile forces in response to electrical stimuli upon MyoD expression. Withdrawal of doxycycline in the middle of 3D culture results in 3.05 and 2.28 times increases in twitch and tetanic forces, respectively, suggesting that temporally-controlled MyoD expression benefits functional myogenic differentiation of transdifferentiated myoblast-like cells. Treatment with CHIR99021, a Wnt activator, and DAPT, a Notch inhibitor, leads to further enhanced contractile forces. The ability of these abundant and potentially patient-specific and disease-specific cells to develop into functional skeletal muscle constructs makes them highly valuable for many applications, such as disease modeling.

Common variants in signaling transcription-factor-binding sites drive phenotypic variability in red blood cell traits

Genome-wide association studies identify genomic variants associated with human traits and diseases. Most trait-associated variants are located within cell-type-specific enhancers, but the molecular mechanisms governing phenotypic variation are less well understood. Here, we show that many enhancer variants associated with red blood cell (RBC) traits map to enhancers that are co-bound by lineage-specific master transcription factors (MTFs) and signaling transcription factors (STFs) responsive to extracellular signals. The majority of enhancer variants reside on STF and not MTF motifs, perturbing DNA binding by various STFs (BMP/TGF-β-directed SMADs or WNT-induced TCFs) and affecting target gene expression. Analyses of engineered human blood cells and expression quantitative trait loci verify that disrupted STF binding leads to altered gene expression. Our results propose that the majority of the RBC-trait-associated variants that reside on transcription-factor-binding sequences fall in STF target sequences, suggesting that the phenotypic variation of RBC traits could stem from altered responsiveness to extracellular stimuli.

YJ5 as an immunohistochemical marker of osteogenic lineage

Overexpression of WLS, an upstream protein in the Wnt pathway, has been implicated in several non-osteogenic tumours. This study represents the first attempt at evaluating WLS expression in various bone and soft tissue tumours using YJ5, a monoclonal antibody specific to WLS, with the aim of elucidating its utility in discerning tumours with aberrant Wnt signalling and as a marker of osteogenic lineage in challenging cases. Tumour tissue sections of 144 bone mass lesions and 63 soft tissue mass lesions were immunostained with the YJ5 antibody following standardised protocols. Subsequent assessment of immunoreactivity segregated cases into one of three groups: absent/weak, moderate, or strong YJ5 immunoreactivity. For the bone tumours, strong YJ5 immunoreactivity was seen in almost all osteosarcomas and chondroblastomas, all osteoblastomas and osteoid osteomas. In contrast, all other cartilaginous tumours, chordomas, aneurysmal bone cysts, chondromyxoid fibromas, most fibrous dysplasias and most giant cell tumours exhibited absent/weak YJ5 immunostaining. For the soft tissue tumours, a more heterogeneous pattern of YJ5 immunoreactivity was observed. Because diffuse and strong YJ5 expression is identified in almost all benign and malignant bone tumours with osteoblastic activity, it can be potentially utilised as an immunohistochemical marker to support osteogenic lineage. If interpreted in the appropriate context, this marker is useful in determining whether a malignant bone tumour is an osteosarcoma, particularly in those subtypes with no or minimal osteoid or unusual morphological features. This marker can also complement SATB2 to denote osteogenic lineage.

Evidence for functional and regulatory cross-talk between Wnt/β-catenin signalling and Mre11-Rad50-Nbs1 complex in the repair of cisplatin-induced DNA cross-links

The canonical Wnt/β-catenin signalling pathway plays a crucial role in a variety of functions including cell proliferation and differentiation, tumorigenic processes and radioresistance in cancer cells. The Mre11–Rad50–Nbs1 (MRN) complex has a pivotal role in sensing and repairing DNA damage. However, it remains unclear whether a connection exists between Wnt/β-catenin signalling and the MRN complex in the repair of cisplatin-induced DNA interstrand cross-links (ICLs). Here, we report that (1) cisplatin exposure results in a significant increase in the levels of MRN complex subunits in human tumour cells; (2) cisplatin treatment stimulates Wnt/β-catenin signalling through increased β-catenin expression; (3) the functional perturbation of Wnt/β-catenin signalling results in aberrant cell cycle dynamics and the activation of DNA damage response and apoptosis; (4) a treatment with CHIR99021, a potent and selective GSK3β inhibitor, augments cisplatin-induced cell death in cancer cells. On the other hand, inactivation of the Wnt/β-catenin signalling with FH535 promotes cell survival. Consistently, the staining pattern of γH2AX-foci is significantly reduced in the cells exposed simultaneously to cisplatin and FH535; and (5) inhibition of Wnt/β-catenin signalling impedes cisplatin-induced phosphorylation of Chk1, abrogates the G2/M phase arrest and impairs recombination-based DNA repair. Our data further show that Wnt signalling positively regulates the expression of β-catenin, Mre11 and FANCD2 at early time points, but declining thereafter due to negative feedback regulation. These results support a model wherein Wnt/β-catenin signalling and MRN complex crosstalk during DNA ICL repair, thereby playing an important role in the maintenance of genome stability.

Wnt Pathway: An Integral Hub for Developmental and Oncogenic Signaling Networks

The Wnt pathway is an integral cell-to-cell signaling hub which regulates crucial development processes and maintenance of tissue homeostasis by coordinating cell proliferation, differentiation, cell polarity, cell movement, and stem cell renewal. When dysregulated, it is associated with various developmental diseases, fibrosis, and tumorigenesis. We now better appreciate the complexity and crosstalk of the Wnt pathway with other signaling cascades. Emerging roles of the Wnt signaling in the cancer stem cell niche and drug resistance have led to development of therapeutics specifically targeting various Wnt components, with some agents currently in clinical trials. This review highlights historical and recent findings on key mediators of Wnt signaling and how they impact antitumor immunity and maintenance of cancer stem cells. This review also examines current therapeutics being developed that modulate Wnt signaling in cancer and discusses potential shortcomings associated with available therapeutics.