Wnt signalling: variety at the core

Perinuclear mitochondrial clustering for mesenchymal-to-epithelial transition in pluripotency induction

Remodeled mitochondria are characteristic of pluripotent stem cells. However, a role for mitochondrial movement and distribution in pluripotency remains unknown. Here, we show that mitochondrial retrograde transport-mediated perinuclear clustering via dynein complex occurs at the early phase of pluripotency induction. Interestingly, this mitochondrial redistribution is regulated by Yamanaka factor OCT4 but not SOX2 or KLF4. This mitochondrial redistribution, which has effect on the efficiency of somatic cell reprogramming, also depends on DRP1-mediated mitochondrial fission. Importantly, perinuclear mitochondrial clustering is required for mesenchymal-to-epithelial transition (MET), an early step in reprogramming, during which β-catenin regulates the MET process. Furthermore, sufficient amount of β-catenin plays a key role in maintaining stabilization of E-CADHERIN. Taken together, these studies show that perinuclear mitochondrial clustering is an essential organellar step for MET process of pluripotency induction, which may shed light on the subcellular relationship between mitochondrial dynamics, pluripotency, and cellular morphology.

Reconstructing signaling histories of single cells via perturbation screens and transfer learning

Manipulating the signaling environment is an effective approach to alter cellular states for broad-ranging applications, from engineering tissues to treating diseases. Such manipulation requires knowing the signaling states and histories of the cells in situ , for which high-throughput discovery methods are lacking. Here, we present an integrated experimental-computational framework that learns signaling response signatures from a high-throughput in vitro perturbation atlas and infers combinatorial signaling activities in in vivo cell types with high accuracy and temporal resolution. Specifically, we generated signaling perturbation atlas across diverse cell types/states through multiplexed sequential combinatorial screens on human pluripotent stem cells. Using the atlas to train IRIS, a neural network-based model, and predicting on mouse embryo scRNAseq atlas, we discovered global features of combinatorial signaling code usage over time, identified biologically meaningful heterogeneity of signaling states within each cell type, and reconstructed signaling histories along diverse cell lineages. We further demonstrated that IRIS greatly accelerates the optimization of stem cell differentiation protocols by drastically reducing the combinatorial space that needs to be tested. This framework leads to the revelation that different cell types share robust signal response signatures, and provides a scalable solution for mapping complex signaling interactions in vivo to guide targeted interventions.

Defects of the spliceosomal gene SNRPB affect osteo- and chondro-differentiation

Although gene splicing occurs throughout the body, the phenotype of spliceosomal defects is largely limited to specific tissues. Cerebro-costo-mandibular syndrome (CCMS) is one such spliceosomal disease, which presents as congenital skeletal dysmorphism and is caused by mutations of SNRPB gene encoding Small Nuclear Ribonucleoprotein Polypeptides B/B' (SmB/B'). This study employed in vitro cell cultures to monitor osteo- and chondro-differentiation and examined the role of SmB/B' in the differentiation process. We found that low levels of SmB/B' by knockdown or mutations of SNRPB led to suppressed osteodifferentiation in Saos-2 osteoprogenitor-like cells, which was accompanied by affected splicing of Dlx5. On the other hand, low SmB/B' led to promoted chondrogenesis in HEPM mesenchymal stem cells. Consistent with other reports, osteogenesis was promoted by the Wnt/β-catenin pathway activator and suppressed by Wnt and BMP blockers, whereas chondrogenesis was promoted by Wnt inhibitors. Suppressed osteogenic markers by SNRPB knockdown were partly rescued by Wnt/β-catenin pathway activation. Reporter analysis revealed that suppression of SNRPB results in attenuated Wnt pathway and/or enhanced BMP pathway activities. SNRPB knockdown altered splicing of TCF7L2 which impacts Wnt/β-catenin pathway activities. This work helps unravel the mechanism underlying CCMS whereby reduced expression of spliceosomal proteins causes skeletal phenotypes.

Transmembrane protein 184B (TMEM184B) promotes expression of synaptic gene networks in the mouse hippocampus

In Alzheimer's Disease (AD) and other dementias, hippocampal synaptic dysfunction and loss contribute to the progression of memory impairment. Recent analysis of human AD transcriptomes has provided a list of gene candidates that may serve as drivers of disease. One such candidate is the membrane protein TMEM184B. To evaluate whether TMEM184B contributes to neurological impairment, we asked whether loss of TMEM184B in mice causes gene expression or behavior alterations, focusing on the hippocampus. Because one major risk factor for AD is age, we compared young adult (5-month-old) and aged (15-month-old) wild type and Tmem184b-mutant mice to assess the dual contributions of age and genotype. TMEM184B loss altered expression of pre- and post-synaptic transcripts by 5 months and continued through 15 months, specifically affecting genes involved in synapse assembly and neural development. Wnt-activated enhancer elements were enriched among differentially expressed genes, suggesting an intersection with this pathway. Few differences existed between young adult and aged mutants, suggesting that transcriptional effects of TMEM184B loss are relatively constant. To understand how TMEM184B disruption may impact behaviors, we evaluated memory using the novel object recognition test and anxiety using the elevated plus maze. Young adult Tmem184b-mutant mice show normal object discrimination, suggesting a lack of memory impairment at this age. However, mutant mice showed decreased anxiety, a phenotype seen in some neurodevelopmental disorders. Taken together, our data suggest that TMEM184B is required for proper synaptic gene expression and anxiety-related behavior and is more likely to be linked to neurodevelopmental disorders than to dementia.

TCF1/LEF1 triggers Wnt-dependent chemokine/cytokine-induced inflammation and cadherin pathways to drive T-ALL cell migration

T-cell acute lymphoblastic leukemia (T-ALL) is a type of aggressive hematologic malignancy. It progresses quickly and it is likely to be fatal within a few months without treatment. Despite the limitations of current clinical therapies, there is an urgent need for novel and targeted therapies. To explore potential targeted therapies, molecular genetic mechanisms of T-ALL metastasis must be uncovered. However, the genes and mechanisms that mediate T-ALL metastasis are largely unknown. Recent insights into T-ALL biology have identified several genes that can be grouped into several targetable signaling pathways. The Wnt/β-catenin signaling pathway is one of the most important pathways. Our work investigated the functions of TCF1 and LEF1 in cell growth and migration mediated by the Wnt signaling pathway. We found that TCF1 and LEF1 knockdown weakly repressed T-ALL cell proliferation but distinctly impaired cell migration. T-ALL metastasis is dependent on cell migration and invasion. Our results displayed that TCF1 and LEF1 regulated T-ALL cell migration by the Wnt-dependent chemokine and cytokine-induced inflammation and cadherin signaling pathways. By transcriptionally regulating these pathways-associated genes, TCF1 and LEF1 inhibited cell adhesion and promoted cell migration and invasion.

TCF7L2 acts as a molecular switch in midbrain to control mammal vocalization through its DNA binding domain but not transcription activation domain

Vocalization is an essential medium for social signaling in birds and mammals. Periaqueductal gray (PAG) a conserved midbrain structure is believed to be responsible for innate vocalizations, but its molecular regulation remains largely unknown. Here, through a mouse forward genetic screening we identified one of the key Wnt/β-catenin effectors TCF7L2/TCF4 controls ultrasonic vocalization (USV) production and syllable complexity during maternal deprivation and sexual encounter. Early developmental expression of TCF7L2 in PAG excitatory neurons is necessary for the complex trait, while TCF7L2 loss reduces neuronal gene expressions and synaptic transmission in PAG. TCF7L2-mediated vocal control is independent of its β-catenin-binding domain but dependent of its DNA binding ability. Patient mutations associated with developmental disorders, including autism spectrum disorders, disrupt the transcriptional repression effect of TCF7L2, while mice carrying those mutations display severe USV impairments. Therefore, we conclude that TCF7L2 orchestrates gene expression in midbrain to control vocal production through its DNA binding but not transcription activation domain.

Wnt Pathway in Pancreatic Development and Pathophysiology

The pancreas is an abdominal gland that serves 2 vital purposes: assist food processing by secreting digestive enzymes and regulate blood glucose levels by releasing endocrine hormones. During embryonic development, this gland originates from epithelial buds located on opposite sites of the foregut endoderm. Pancreatic cell specification and maturation are coordinated by a complex interplay of extrinsic and intrinsic signaling events. In the recent years, the canonical Wnt/β-catenin pathway has emerged as an important player of pancreas organogenesis, regulating pancreatic epithelium specification, compartmentalization and expansion. Importantly, it has been suggested to regulate proliferation, survival and function of adult pancreatic cells, including insulin-secreting β-cells. This review summarizes recent work on the role of Wnt/β-catenin signaling in pancreas biology from early development to adulthood, emphasizing on its relevance for the development of new therapies for pancreatic diseases.

Mammal comparative tendon biology: advances in regulatory mechanisms through a computational modeling

There is high clinical demand for the resolution of tendinopathies, which affect mainly adult individuals and animals. Tendon damage resolution during the adult lifetime is not as effective as in earlier stages where complete restoration of tendon structure and property occurs. However, the molecular mechanisms underlying tendon regeneration remain unknown, limiting the development of targeted therapies. The research aim was to draw a comparative map of molecules that control tenogenesis and to exploit systems biology to model their signaling cascades and physiological paths. Using current literature data on molecular interactions in early tendon development, species-specific data collections were created. Then, computational analysis was used to construct Tendon NETworks in which information flow and molecular links were traced, prioritized, and enriched. Species-specific Tendon NETworks generated a data-driven computational framework based on three operative levels and a stage-dependent set of molecules and interactions (embryo-fetal or prepubertal) responsible, respectively, for signaling differentiation and morphogenesis, shaping tendon transcriptional program and downstream modeling of its fibrillogenesis toward a mature tissue. The computational network enrichment unveiled a more complex hierarchical organization of molecule interactions assigning a central role to neuro and endocrine axes which are novel and only partially explored systems for tenogenesis. Overall, this study emphasizes the value of system biology in linking the currently available disjointed molecular data, by establishing the direction and priority of signaling flows. Simultaneously, computational enrichment was critical in revealing new nodes and pathways to watch out for in promoting biomedical advances in tendon healing and developing targeted therapeutic strategies to improve current clinical interventions.

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.

An efficient method of inducing differentiation of mouse embryonic stem cells into primitive endodermal cells

Primitive Endoderm (PrE) is an extraembryonic structure derived from inner cell mass (ICM) in the blastocysts. Its interaction with the epiblast is critical to sustain embryonic growth and embryonic pattern. In this study, we reported a simple and efficient method to induce the differentiation of mouse Embryonic Stem Cells (mESCs) into PrE cells. In the process of ESC monolayer adherent culture, 1 μM atRA and 10 μM CHIR inducers were used to activate RA and Wnt signaling pathways respectively. After 9 days of differentiation, the proportion of PrE cells was up to 85%. Further studies indicated that Wnt signaling pathway acted as a switch that RA induces mESCs differentiation between SMC and PrE cell. In the presence of only RA signaling, mESCs adopted the fate of smooth muscle cells (SMCs); Simultaneous activation of the Wnt signaling pathway changed the differentiation fate of mESCs into PrE cells. This efficient induction method can provide new cellular resources and models for relevant studies of PrE.

Evolutionary diversification of the canonical Wnt signaling effector TCF/LEF in chordates

Wnt signaling is essential during animal development and regeneration, but also plays an important role in diseases such as cancer and diabetes. The canonical Wnt signaling pathway is one of the most conserved signaling cascades in the animal kingdom, with the T‐cell factor/lymphoid enhancer factor (TCF/LEF) proteins being the major mediators of Wnt/β‐catenin‐regulated gene expression. In comparison with invertebrates, vertebrates possess a high diversity of TCF/LEF family genes, implicating this as a possible key change to Wnt signaling at the evolutionary origin of vertebrates. However, the precise nature of this diversification is only poorly understood. The aim of this study is to clarify orthology, paralogy, and isoform relationships within the TCF/LEF gene family within chordates via in silico comparative study of TCF/LEF gene structure, molecular phylogeny, and gene synteny. Our results support the notion that the four TCF/LEF paralog subfamilies in jawed vertebrates (gnathostomes) evolved via the two rounds of whole‐genome duplications that occurred during early vertebrate evolution. Importantly, gene structure comparisons and synteny analysis of jawless vertebrate (cyclostome) TCFs suggest that a TCF7L2‐like form of gene structure is a close proxy for the ancestral vertebrate structure. In conclusion, we propose a detailed evolutionary path based on a new pre‐whole‐genome duplication vertebrate TCF gene model. This ancestor gene model highlights the chordate and vertebrate innovations of TCF/LEF gene structure, providing the foundation for understanding the role of Wnt/β‐catenin signaling in vertebrate evolution.

Progesterone Can Directly Inhibit the Life Activities of Toxoplasma gondii In Vitro through the Progesterone Receptor Membrane Component (PGRMC)

Toxoplasma gondii (T. gondii), as an opportunistic pathogen, has special pathogenic effects on pregnant animals and humans. Progesterone (P4) is a critical hormone that supports pregnancy, and its levels fluctuate naturally during early pregnancy. However, little is known about the association of host P4 levels with the infectivity and pathogenicity of T. gondii. Our study showed that P4 significantly inhibited the invasion and proliferation of tachyzoites, resulting in abnormal cytoskeletal daughter budding and subsequent autophagy in vitro. To investigate the underlying mechanism, we identified a Toxoplasma gondii progesterone membrane receptor protein (TgPGRMC) that was localized to the mitochondrion and closely related to the effect of P4 on tachyzoites. The knockout of the pgrmc gene conferred resistance to P4 inhibitory effects. Our results prove the direct relationship between P4 single factors and T. gondii in vitro and demonstrate that TgPGRMC is an important link between T. gondii and P4, providing a new direction for research on T. gondii infection during pregnancy.

A pyridinium‑type fullerene derivative suppresses primary effusion lymphoma cell viability via the downregulation of the Wnt signaling pathway through the destabilization of β‑catenin

Primary effusion lymphoma (PEL) is defined as a rare subtype of non-Hodgkin's B cell lymphoma, which is caused by Kaposi's sarcoma-associated herpesvirus (KSHV) in immunosuppressed patients. PEL is an aggressive type of lymphoma and is frequently resistant to conventional chemotherapeutics. Therefore, the discovery of novel drug candidates for the treatment of PEL is of utmost importance. In order to discover potential novel anti-tumor compounds against PEL, the authors previously developed a pyrrolidinium-type fullerene derivative, 1,1,1′,1′-tetramethyl [60]fullerenodipyrrolidinium diiodide (derivative #1), which induced the apoptosis of PEL cells via caspase-9 activation. In the present study, the growth inhibitory effects of pyrrolidinium-type (derivatives #1 and #2), pyridinium-type (derivatives #3 and #5 to #9) and anilinium-type fullerene derivatives (derivative #4) against PEL cells were evaluated. This analysis revealed a pyridinium-type derivative (derivative #5; 3- 5′-(etho-xycarbonyl)-1′,5′-dihydro-2′H-[5,6]fullereno-C₆₀-I_h-[1,9-c]pyrrol-2′-yl]-1-methylpyridinium iodide), which exhibited antitumor activity against PEL cells via the downregulation of Wnt/β-catenin signaling. Derivative #5 suppressed the viability of KSHV-infected PEL cells compared with KSHV-uninfected B-lymphoma cells. Furthermore, derivative #5 induced the destabilization of β-catenin and suppressed β-catenin-TCF4 transcriptional activity in PEL cells. It is known that the constitutive activation of Wnt/β-catenin signaling is essential for the growth of KSHV-infected cells. The Wnt/β-catenin activation in KSHV-infected cells is mediated by KSHV latency-associated nuclear antigen (LANA). The data demonstrated that derivative #5 increased β-catenin phosphorylation, which resulted in β-catenin polyubiquitination and subsequent degradation. Thus, derivative #5 overcame LANA-mediated β-catenin stabilization. Furthermore, the administration of derivative #5 suppressed the development of PEL cells in the ascites of SCID mice with tumor xenografts derived from PEL cells. On the whole, these findings provide evidence that the pyridinium-type fullerene derivative #5 exhibits antitumor activity against PEL cells in vitro and in vivo. Thus, derivative #5 may be utilized as a novel therapeutic agent for the treatment of PEL.

Neuroadaptations and TGF-β signaling: emerging role in models of neuropsychiatric disorders

Neuropsychiatric diseases are manifested by maladaptive behavioral plasticity. Despite the greater understanding of the neuroplasticity underlying behavioral adaptations, pinpointing precise cellular mediators has remained elusive. This has stymied the development of pharmacological interventions to combat these disorders both at the level of progression and relapse. With increased knowledge on the putative role of the transforming growth factor (TGF- β) family of proteins in mediating diverse neuroadaptations, the influence of TGF-β signaling in regulating maladaptive cellular and behavioral plasticity underlying neuropsychiatric disorders is being increasingly elucidated. The current review is focused on what is currently known about the TGF-β signaling in the central nervous system in mediating cellular and behavioral plasticity related to neuropsychiatric manifestations.

Embryonic Stem Cell Differentiation Is Regulated by SET through Interactions with p53 and β-Catenin

The multifunctional histone chaperone, SET, is essential for embryonic development in the mouse. Previously, we identified SET as a factor that is rapidly downregulated during embryonic stem cell (ESC) differentiation, suggesting a possible role in the maintenance of pluripotency. Here, we explore SET's function in early differentiation. Using immunoprecipitation coupled with protein quantitation by LC-MS/MS, we uncover factors and complexes, including P53 and β-catenin, by which SET regulates lineage specification. Knockdown for P53 in SET-knockout (KO) ESCs partially rescues lineage marker misregulation during differentiation. Paradoxically, SET-KO ESCs show increased expression of several Wnt target genes despite reduced levels of active β-catenin. Further analysis of RNA sequencing datasets hints at a co-regulatory relationship between SET and TCF proteins, terminal effectors of Wnt signaling. Overall, we discover a role for both P53 and β-catenin in SET-regulated early differentiation and raise a hypothesis for SET function at the β-catenin-TCF regulatory axis.

Adenosine A2A receptor null chondrocyte transcriptome resembles that of human osteoarthritic chondrocytes

Adenosine signaling plays a critical role in the maintenance of articular cartilage and may serve as a novel therapeutic for osteoarthritis (OA), a highly prevalent and morbid disease without effective therapeutics in the current market. Mice lacking adenosine A2A receptors (A2AR) develop spontaneous OA by 16 weeks of age, a finding relevant to human OA since loss of adenosine signaling due to diminished adenosine production (NT5E deficiency) also leads to development of OA in mice and humans. To better understand the mechanism by which A2AR and adenosine generation protect from OA development, we examined differential gene expression in neonatal chondrocytes from WT and A2AR null mice. Analysis of differentially expressed genes was analyzed by KEGG pathway analysis, and oPOSSUM and the flatiron database were used to identify transcription factor binding enrichment, and tissue-specific network analyses and patterns were compared to gene expression patterns in chondrocytes from patients with OA. There was a differential expression of 2211 genes (padj<0.05). Pathway enrichment analysis revealed that pro-inflammatory changes, increased metalloprotease, reduced matrix organization, and homeostasis are upregulated in A2AR null chondrocytes. Moreover, stress responses, including autophagy and HIF-1 signaling, seem to be important drivers of OA and bear marked resemblance to the human OA transcriptome. Although A2AR null mice are born with grossly intact articular cartilage, we identify here the molecular foundations for early-onset OA in these mice, further establishing their role as models for human disease and the potential use of adenosine as a treatment for human disease.

TGIF1 plays a carcinogenic role in esophageal squamous cell carcinoma through the Wnt/β‑catenin and Akt/mTOR signaling pathways

TGFB induced factor homeobox 1 (TGIF1), a transcriptional corepressor, has been reported to be involved in tumorigenesis and cancer development. However, the role of TGIF1 in the growth and metastasis of esophageal cancer is poorly studied. In the present study, it was found that TGIF1 was highly expressed in esophageal cancer tissues and cell lines. The silencing of TGIF1 by siRNA interference significantly inhibited the proliferation, migration, invasion and epithelial‑mesenchymal transition (EMT) process of KYSE‑150 esophageal cancer cells, and promoted cell apoptosis. Correspondingly, the upregulation of TGIF1 significantly promoted the proliferation and metastatic potential of Eca‑109 cells, and reduced apoptosis. Furthermore, the data indicated that the Wnt/β‑catenin and Akt/mammalian target of rapamycin (mTOR) signaling pathways were inhibited by TGIF1 knockdown, and were promoted by the overexpression of TGIF1. It was also confirmed that TGIF1 knockdown reduced tumor growth, inhibited Wnt/β‑catenin and Akt/mTOR pathway activation, and reversed the TGF‑β1‑mediated EMT process in a tumor xenograft model. Taken together, the data of the present study suggest that TGIF1 plays an oncogenic role in the progression of esophageal cancer. It may carry out this role by regulating the Wnt/β‑catenin and Akt/mTOR signaling pathways.

Central signalling cross-talk between insulin and leptin in glucose and energy homeostasis

Energy homeostasis is controlled by an intricate regulatory system centred in the brain. The peripheral adiposity signals insulin and leptin play a crucial role in this system by informing the brain of the energy status of the body and mediating their catabolic effects through signal transduction in hypothalamic areas that control food intake, energy expenditure and glucose metabolism. Disruptions of insulin and leptin signalling can result in diabetes and obesity. The central signalling cross-talk between insulin and leptin is essential for maintenance of normal healthy energy homeostasis. An important role of leptin in glucoregulation has been revealed. Typically regarded as being controlled by insulin, the control of glucose homeostasis critically depends on functional leptin action. Leptin, on the other hand, is able to lower glucose levels in the absence of insulin, although insulin is necessary for long-term stabilisation of euglycaemia. Evidence from rodent models and human patients suggests that leptin improves insulin sensitivity in type 1 diabetes. The signalling cross-talk between insulin and leptin is likely conveyed by the WNT/β-catenin pathway. Leptin activates WNT/β-catenin signalling, leading to inhibition of glycogen synthase kinase-3β, a key inhibitor of insulin action, thereby facilitating improved insulin signal transduction and sensitisation of insulin action. Interestingly, insights into the roles of insulin and leptin in insects and fish indicate that leptin may have initially evolved as a glucoregulatory hormone and that its anorexigenic and body weight regulatory function was acquired throughout evolution. Furthermore, the regulation of both central and peripheral control of energy homeostasis is tightly controlled by the circadian clock, allowing adaptation of homeostatic processes to environmental cues.

Distinct roles of LRP5 and LRP6 in Wnt signaling regulation in the retina

Dysregulation of Wnt signaling is implicated in multiple ocular disorders. The roles of Wnt co-receptors LRP5 and LRP6 in Wnt signaling regulation remain elusive, as most retinal cells express both of the co-receptors. To address this question, LRP5 and LRP6 were individually knocked-out in a human retinal pigment epithelium cell line using the CRISPR-Cas9 technology. Wnt signaling activity induced by various Wnt ligands was measured using wild-type and the KO cell lines. The results identified three groups of Wnt ligands based on their co-receptor specificity: 1) activation of Wnt signaling only through LRP6, 2) through both LRP5 and LRP6 and 3) predominantly through LRP5. These results indicate that LRP5 and LRP6 have differential roles in Wnt signaling regulation.

The Potential of T Cell Factor 1 in Sustaining CD8+ T Lymphocyte-Directed Anti-Tumor Immunity

Simple Summary

The transcription factor T cell factor 1 (TCF1), encoded by the TCF7 gene, is a key regulator of T-cell fate, which is known to promote T cell proliferation and establish T cell stemness. Importantly, increasing evidence has demonstrated that TCF1 is a critical determinant of the success of anti-tumor immunotherapy, implicating that TCF1 is a promising biomarker and therapeutic target in cancer. In recent years, new findings have emerged to provide a clearer view of TCF1 and its role in T cell biology. In this review, we aim to provide a comprehensive outline of the most recent literature on the role of TCF1 in T cell development and to discuss the potential of TCF1 in sustaining CD8⁺ T lymphocyte-directed anti-tumor immunity.

Abstract

T cell factor 1 (TCF1) is a transcription factor that has been highlighted to play a critical role in the promotion of T cell proliferation and maintenance of cell stemness in the embryonic and CD8⁺ T cell populations. The regulatory nature of TCF1 in CD8⁺ T cells is of great significance, especially within the context of T cell exhaustion, which is linked to the tumor and viral escape in pathological contexts. Indeed, inhibitory signals, such as programmed cell death 1 (PD-1) and cytotoxic-T-lymphocyte-associated protein 4 (CTLA-4), expressed on exhausted T lymphocytes (T_EX), have become major therapeutic targets in immune checkpoint blockade (ICB) therapy. The significance of TCF1 in the sustenance of CTL-mediated immunity against pathogens and tumors, as well as its recently observed necessity for an effective anti-tumor immune response in ICB therapy, presents TCF1 as a potentially significant biomarker and/or therapeutic target for overcoming CD8⁺ T cell exhaustion and resistance to ICB therapy. In this review, we aim to outline the recent findings on the role of TCF1 in T cell development and discuss its implications in anti-tumor immunity.

Distinct populations of crypt-associated fibroblasts act as signaling hubs to control colon homeostasis

Despite recent progress in recognizing the importance of mesenchymal cells for the homeostasis of the intestinal system, the current picture of how these cells communicate with the associated epithelial layer remains unclear. To describe the relevant cell populations in an unbiased manner, we carried out a single-cell transcriptome analysis of the adult murine colon, producing a high-quality atlas of matched colonic epithelium and mesenchyme. We identify two crypt-associated colonic fibroblast populations that are demarcated by different strengths of platelet-derived growth factor receptor A (Pdgfra) expression. Crypt-bottom fibroblasts (CBFs), close to the intestinal stem cells, express low levels of Pdgfra and secrete canonical Wnt ligands, Wnt potentiators, and bone morphogenetic protein (Bmp) inhibitors. Crypt-top fibroblasts (CTFs) exhibit high Pdgfra levels and secrete noncanonical Wnts and Bmp ligands. While the Pdgfralow cells maintain intestinal stem cell proliferation, the Pdgfrahigh cells induce differentiation of the epithelial cells. Our findings enhance our understanding of the crosstalk between various colonic epithelial cells and their associated mesenchymal signaling hubs along the crypt axis-placing differential Pdgfra expression levels in the spotlight of intestinal fibroblast identity.

PAR1&2 driven placenta EVT invasion act via LRP5/6 as coreceptors

While the involvement of protease-activated receptors (PARs) in the physiological regulation of human placenta development, as in tumor biology, is recognized, the molecular pathway is unknown. We evaluated the impact of PAR₁ and PAR₂ function in cytotrophoblast (CTB) proliferation and invasion in a system of extravillous trophoblast (EVT) organ culture and in human cell-lines. Activation of PAR₁ - and PAR₂ -induced EVT invasion and proliferation, while the shRNA silencing of low-density lipoprotein receptor-related protein 5/6 (LRP5/6) inhibited these processes. PAR₁ and PAR₂ effectively induce β-catenin stabilization in a manner similar to that shown for the canonical β-catenin stabilization pathway yet independent of Wnts. Immunoprecipitation analyses and protein-protein docking demonstrated the co-association between either PAR₁ or PAR₂ with LRP5/6 forming an axis of PAR-LRP5/6-Axin. Noticeably, in PAR₁ -PAR₂ heterodimers a dominant role is assigned to PAR₂ over PAR₁ as shown by inhibition of PAR₁ -induced β-catenin levels, and Dvl nuclear localization. This inhibition takes place either by shRNA silenced hPar2 or in the presence of a TrPAR₂ devoid its cytoplasmic tail. Indeed, TrPAR₂ cannot form the PAR₁ -PAR₂ complex, obstructing thereby the flow of signals downstream. Elucidation of the mechanism of PAR-induced invasion contributes to therapeutic options highlighting key partners in the process.

Regulation of epithelial-mesenchymal transition and organoid morphogenesis by a novel TGFβ-TCF7L2 isoform-specific signaling pathway

Alternative splicing contributes to diversification of gene function, yet consequences of splicing on functions of specific gene products is poorly understood. The major transcription factor TCF7L2 undergoes alternative splicing but the biological significance of TCF7L2 isoforms has remained largely to be elucidated. Here, we find that the TCF7L2 E-isoforms maintain, whereas the M and S isoforms disrupt morphogenesis of 3D-epithelial cell-derived organoids via regulation of epithelial-mesenchymal transition (EMT). Remarkably, TCF7L2E2 antagonizes, whereas TCF7L2M2/S2 promotes EMT-like effects in epithelial cells induced by transforming growth factor beta (TGFβ) signaling. In addition, we find TGFβ signaling reduces the proportion of TCF7L2E to TCF7L2M/S protein in cells undergoing EMT. We also find that TCF7L2 operates via TGFβ-Smad3 signaling to regulate EMT. Collectively, our findings unveil novel isoform-specific functions for the major transcription factor TCF7L2 and provide novel links between TCF7L2 and TGFβ signaling in the control of EMT-like responses and epithelial tissue morphogenesis.

Waterborne Cu exposure increased lipid deposition and lipogenesis by affecting Wnt/β-catenin pathway and the β-catenin acetylation levels of grass carp Ctenopharyngodon idella

Lipid metabolism could be used as a biomarker for environmental monitoring of metal pollution, including Cu. Given the potential role of the Wnt/β-catenin signaling pathway and acetylation in lipid metabolism, the aim of this study was to investigate the mechanism of Wnt signaling and acetylation mediating Cu-induced lipogenesis. Grass carp Ctenopharyngodon idella, widely distributed freshwater teleost, were used as the model. We found that waterborne Cu exposure increased the accumulation of Cu and lipid, up-regulated lipogenesis, suppressed Wnt signaling, reduced β-catenin protein level and its nuclear location, reduced the sirt1 mRNA levels and up-regulated the β-catenin acetylation level. Further investigation found that Cu up-regulated lipogenesis through Wnt/β-catenin pathway; Cu regulated the β-catenin acetylation, and K311 was the key acetylated residue after Cu incubation. SIRT1 mediated Cu-induced changes of acetylated β-catenin and played an essential role in nuclear accumulation of β-catenin and Cu-induced lipogenesis. Cu facilitated lipid accumulation via the regulation of Wnt pathway by SIRT1. For the first time, our study uncovered the novel mechanism for Wnt/β-catenin pathway and β-catenin acetylation levels mediating Cu-induced lipid deposition, which provided insights into the association between Cu exposure and lipid metabolism in fish and had important environmental implications for monitoring metal pollution in the water by using new biomarkers involved in lipid metabolism.

The Distinct Role of Tcfs and Lef1 in the Self-Renewal or Differentiation of Mouse Embryonic Stem Cells

Background and Objectives

Tcfs and Lef1 are DNA-binding transcriptional factors in the canonical Wnt signaling pathway. In the absence of β-catenin, Tcfs and Lef1 generally act as transcriptional repressors with co-repressor proteins such as Groucho, CtBP, and HIC-5. However, Tcfs and Lef1 turn into transcriptional activators during the interaction with β-catenin. Therefore, the activity of Tcfs and Lef1 is regulated by β-catenin. However, the intrinsic role of Tcfs and Lef1 has yet to be examined. The purpose of this study was to determine whether Tcfs and Lef1 play differential roles in the regulation of self-renewal and differentiation of mouse ES cells.

Methods and Results

Interestingly, the expression of Tcfs and Lef1 was dynamically altered under various differentiation conditions, such as removal of LIF, EB formation and neuronal differentiation in N2B27 media, suggesting that the function of each Tcf and Lef1 may vary in ES cells. Ectopic expression of Tcf1 or the dominant negative form of Lef1 (Lef1-DN) contributes to ES cells to self-renew in the absence of leukemia inhibitory factor (LIF), whereas ectopic expression of Tcf3, Lef1 or Tcf1-DN did not support ES cells to self-renew. Ectopic expression of either Lef1 or Lef1-DN blocked neuronal differentiation, suggesting that the transient induction of Lef1 was necessary for the initiation and progress of differentiation. ChIP analysis shows that Tcf1 bound to Nanog promoter and ectopic expression of Tcf1 enhanced the transcription of Nanog.

Conclusions

The overall data suggest that Tcf1 plays a critical role in the maintenance of stemness whereas Lef1 is involved in the initiation of differentiation.

Diverse LEF/TCF Expression in Human Colorectal Cancer Correlates with Altered Wnt-Regulated Transcriptome in a Meta-Analysis of Patient Biopsies

Aberrantly activated Wnt signaling causes cellular transformation that can lead to human colorectal cancer. Wnt signaling is mediated by Lymphoid Enhancer Factor/T-Cell Factor (LEF/TCF) DNA-binding factors. Here we investigate whether altered LEF/TCF expression is conserved in human colorectal tumor sample and may potentially be correlated with indicators of cancer progression. We carried out a meta-analysis of carefully selected publicly available gene expression data sets with paired tumor biopsy and adjacent matched normal tissues from colorectal cancer patients. Our meta-analysis confirms that among the four human LEF/TCF genes, LEF1 and TCF7 are preferentially expressed in tumor biopsies, while TCF7L2 and TCF7L1 in normal control tissue. We also confirm positive correlation of LEF1 and TCF7 expression with hallmarks of active Wnt signaling (i.e., AXIN2 and LGR5). We are able to correlate differential LEF/TCF gene expression with distinct transcriptomes associated with cell adhesion, extracellular matrix organization, and Wnt receptor feedback regulation. We demonstrate here in human colorectal tumor sample correlation of altered LEF/TCF gene expression with quantitatively and qualitatively different transcriptomes, suggesting LEF/TCF-specific transcriptional regulation of Wnt target genes relevant for cancer progression and survival. This bioinformatics analysis provides a foundation for future more detailed, functional, and molecular analyses aimed at dissecting such functional differences.

Crimean-Congo hemorrhagic fever virus infection triggers the upregulation of the Wnt signaling pathway inhibitor genes

Crimean-Congo hemorrhagic fever virus (CCHFV) is a highly pathogenic agent. Thus far, vaccines and specific antiviral therapies are not available against the threat of infection. Our knowledge regarding its pathogenesis is indeed limited, and thus, developing effective antiviral therapies is hampered. Several studies have demonstrated that the CCHFV infection has an impact on numerous signal transduction pathways. In parallel, the Wnt signaling pathway components are responsible for different important biological processes including cell fate determination, cell migration and cell polarity. Moreover, its implication among several virus infections has been proven, yet little is known in reference to which components of the Wnt pathway are being activated/inhibited as a response to the infection. Our aim was to elicit the influence of the CCHFV infection on adenocarcinomic human alveolar basal epithelial cells in vitro regarding the Wnt signaling pathway-related genes. Gene-expression changes of 92 Wnt-associated genes were examined 48 h post-infection. Furthermore, β-catenin levels were compared in the infected and uninfected cells. Significant changes were observed in the case of 13 genes. The majority of the upregulated genes are associated with the inhibition of the Wnt/β-catenin signaling. Additionally, infected cells expressed less β-catenin. Our findings suggest that CCHFV blocks the Wnt/β-catenin pathway. Our study corroborates the link between CCHFV infection and the Wnt signaling pathways. In addition, it broadens our knowledge in the CCHFV pathomechanism.

Polymorphisms in the CTLA4 promoter sequence are associated with canine hypoadrenocorticism

Background

Canine hypoadrenocorticism is an immune-mediated endocrinopathy that shares both clinical and pathophysiological similarities with Addison’s disease in humans. Several dog breeds are overrepresented in the disease population, suggesting that a genetic component is involved, although this is likely to be polygenic. Previous research has implicated CTLA4 as a potential susceptibility gene. CTLA4 is an important regulator of T cell function and polymorphisms/mutations in CTLA4 have been associated with a number of autoimmune phenotypes in both humans and rodent models of autoimmunity. The aim of the current study was to undertake a case:control association study of CTLA4 promotor polymorphisms in three dog breeds, cocker spaniels, springer spaniels and West Highland white terriers (WHWT).

Results

Polymorphisms in the CTLA4 promoter were determined by PCR and sequence-based typing. There were significant associations with three promoter haplotypes in cocker spaniels (p = 0.003). A series of SNPs were also associated with hypoadrenocorticism in cocker spaniels and springer spaniels, including polymorphisms in predicted NFAT and SP1 transcription factor binding sites.

Conclusions

This study provides further evidence that CTLA4 promotor polymorphisms are associated with this complex genetic disease and supports an immune mediated aetiopathogenesis of canine hypoadrenocorticism.

Miltefosine suppression of Pten null T-ALL leukemia via β-catenin degradation through inhibition of pT308-Akt and TGFβ1/Smad3

Pten deletion in the hematopoietic stem cells (HSC) causes a myeloproliferative disorder, which may subsequently develop into a T-cell acute lymphoblastic leukemia (T-ALL). β-catenin expression was dramatically increased in the c-Kit^midCD3⁺Lin^- leukemia stem cells (LSC) and was critical for T-ALL development. Therefore, the inactivation of β-catenin in LSC may have a potential to eliminate the LSC. In this study, we investigated the mechanism of enhancement of the β-catenin expression and subsequently used a drug to inactivate β-catenin expression in T-ALL. Western blot (WB) analysis revealed an increased level of β-catenin in the leukemic cells, but not in the pre-leukemic cells. Furthermore, the WB analysis of the thymic cells from different stages of leukemia development showed that increased expression of β-catenin was not via the pS9-GSK3β signaling, but was dependent on the pT308-Akt activation. Miltefosine (Hexadecylphosphocholine) is the first oral anti-Leishmania drug, which is a phospholipid agent and has been shown to inhibit the PI3K/Akt activity. Treatment of the Pten^Δ/Δ leukemic mice with Miltefosine for different durations demonstrated that the pT308-Akt and the β-catenin expressions were inhibited in the leukemia blast cells. Miltefosine treatment also suppressed the TGFβ1/Smad3 signaling pathway. Analysis of TGFβ1 in the sorted subpopulations of the blast cells showed that TGFβ1 was secreted by the CD3⁺CD4^- subpopulation and may exert effects on the subpopulations of both CD3⁺CD4⁺ and CD3⁺CD4^- leukemia blast cells. When a TGFβR1 inhibitor, SB431542 was injected into the Pten^Δ/Δ leukemic mice, the Smad3 and β-catenin expressions were down-regulated. On the basis of the results, we conclude that Miltefosine can suppress leukemia by degrading β-catenin through repression of the pT308-Akt and TGFβ1/Smad3 signaling pathways. This study demonstrates a possibility to inhibit Pten loss-associated leukemia genesis via targeting Akt and Smad3.

miR‑20b promotes growth of non‑small cell lung cancer through a positive feedback loop of the Wnt/β‑catenin signaling pathway

microRNAs (miRNAs or miRs) are endogenous noncoding single‑stranded RNA molecules that can regulate gene expression by targeting the 3'‑untranslated region and play an important role in many biological and pathological processes, such as inflammation and cancer. In this study, we found that miR‑20b was significantly increased in human non‑small cell lung cancer (NSCLC) cell lines and patient tissues, suggesting that it may possess a carcinogenic role in lung cancer. This miRNA promoted the proliferation, migration and invasion of NSCLC cells by targeting and downregulating the expression of adenomatous polyposis coli (APC), which is a negative regulator of the canonical Wnt signaling pathway. Wnt signaling activation may increase transcription of miR‑20b. Therefore, miR‑20b and canonical Wnt signaling were coupled through a feed‑forward positive feedback loop, forming a biological regulatory circuit. Finally, an in vivo investigation further demonstrated that an increase in miR‑20b promoted the growth of cancer cells. Overall, our findings offer evidence that miR‑20b may contribute to the development of NSCLC by inhibiting APC via the canonical Wnt signaling pathway.

Fine-Tuning Mybl2 Is Required for Proper Mesenchymal-to-Epithelial Transition during Somatic Reprogramming

During somatic reprogramming, Yamanaka’s pioneer factors regulate a complex sequence of molecular events leading to the activation of a network of pluripotency factors, ultimately resulting in the acquisition and maintenance of a pluripotent state. Here, we show that, contrary to the pluripotency factors studied so far, overexpression of Mybl2 inhibits somatic reprogramming. Our results demonstrate that Mybl2 levels are crucial to the dynamics of the reprogramming process. Mybl2 overexpression changes chromatin conformation, affecting the accessibility of pioneer factors to the chromatin and promoting accessibility for early immediate response genes known to be reprogramming blockers. These changes in the chromatin landscape ultimately lead to a deregulation of key genes that are important for the mesenchymal-to-epithelial transition. This work defines Mybl2 level as a gatekeeper for the initiation of reprogramming, providing further insights into the tight regulation and required coordination of molecular events that are necessary for changes in cell fate identity during the reprogramming process.

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Deletion and overexpression of MYBL2 pluripotency factor inhibit somatic reprogramming

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Mybl2 overexpression affects the accessibility of pioneer factors to the chromatin

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Mybl2 overexpression promotes accessibility of reprogramming blockers to the chromatin

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High Mybl2 levels deregulate key genes for proper MET, a requirement for reprogramming

LRP11 activates β-catenin to induce PD-L1 expression in prostate cancer

Prostate cancer (PRAD) is associated with abnormal cholesterol metabolism and low-density lipoprotein (LDL) receptor-related protein (LRP) family is essential for the homeostasis of cholesterol. Immune check points like PD-L1 are vital for tumour cells to evade immune attack. However, the potential cross-talk between these two pathways has not been explored before in PRAD. Insight from the regulation mechanism of PD-L1 in PRAD may help to optimise PD-L1 based immunotherapy. In this study, we investigated a regulation network of LRP11/β-catenin/PD-L1 in PRAD. We showed that the expression of LRP11 and PD-L1 was up-regulated in PRAD compared to paired normal tissues. LRP11 expression was positively correlated to PD-L1 expression in PRAD tissues. Further experiments in two PRAD cell lines with LRP11 over-expression and knockdown showed that LRP11 induced PD-L1 expression through β-catenin signalling. In addition, LRP11 over-expression in PRAD cell line induced immunosuppression of Jurkat cell in in-vitro co-culture system. The effects of LRP11 could be blocked by neutralising LRP11 or PD-L1 antibody. Our results provide evidence for a novel regulation mechanism of PD-L1 expression in PRAD and LRP11 may be a potential therapeutic target in PRAD.

Lef1 regulates caveolin expression and caveolin dependent endocytosis, a process necessary for Wnt5a/Ror2 signaling during Xenopus gastrulation

The activation of distinct branches of the Wnt signaling network is essential for regulating early vertebrate development. Activation of the canonical Wnt/β-catenin pathway stimulates expression of β-catenin-Lef/Tcf regulated Wnt target genes and a regulatory network giving rise to the formation of the Spemann organizer. Non-canonical pathways, by contrast, mainly regulate cell polarization and migration, in particular convergent extension movements of the trunk mesoderm during gastrulation. By transcriptome analyses, we found caveolin1, caveolin3 and cavin1 to be regulated by Lef1 in the involuting mesoderm of Xenopus embryos at gastrula stages. We show that caveolins and caveolin dependent endocytosis are necessary for proper gastrulation, most likely by interfering with Wnt5a/Ror2 signaling. Wnt5a regulates the subcellular localization of receptor complexes, including Ror2 homodimers, Ror2/Fzd7 and Ror2/dsh heterodimers in an endocytosis dependent manner. Live-cell imaging revealed endocytosis of Ror2/caveolin1 complexes. In Xenopus explants, in the presence of Wnt5a, these receptor clusters remain stable exclusively at the basolateral side, suggesting that endocytosis of non-canonical Wnt/receptor complexes preferentially takes place at the apical membrane. In support of this blocking endocytosis with inhibitors prevents the effects of Wnt5a. Thus, target genes of Lef1 interfere with Wnt5a/Ror2 signaling to coordinate gastrulation movements.

Perturbed myoepithelial cell differentiation in BRCA mutation carriers and in ductal carcinoma in situ

Myoepithelial cells play key roles in normal mammary gland development and in limiting pre-invasive to invasive breast tumor progression, yet their differentiation and perturbation in ductal carcinoma in situ (DCIS) are poorly understood. Here, we investigated myoepithelial cells in normal breast tissues of BRCA1 and BRCA2 germline mutation carriers and in non-carrier controls, and in sporadic DCIS. We found that in the normal breast of non-carriers, myoepithelial cells frequently co-express the p63 and TCF7 transcription factors and that p63 and TCF7 show overlapping chromatin peaks associated with differentiated myoepithelium-specific genes. In contrast, in normal breast tissues of BRCA1 mutation carriers the frequency of p63⁺TCF7⁺ myoepithelial cells is significantly decreased and p63 and TCF7 chromatin peaks do not overlap. These myoepithelial perturbations in normal breast tissues of BRCA1 germline mutation carriers may play a role in their higher risk of breast cancer. The fraction of p63⁺TCF7⁺ myoepithelial cells is also significantly decreased in DCIS, which may be associated with invasive progression.

lncRNA FAM99A is downregulated in preeclampsia and exerts a regulatory effect on trophoblast cell invasion, migration and apoptosis

Preeclampsia (PE) is a complication of pregnancy, and a leading cause of maternal mortality and morbidity worldwide. Recently, the dysregulation of long non‑coding RNAs (lncRNAs) has been reported to contribute to the pathogenesis and progression of PE. This study aimed to examine the alterations in the lncRNA family with sequence similarity 99 member A (FAM99A) in PE and its effects on trophoblasts. The results of reverse transcription‑quantitative PCR indicated that the expression levels of FAM99A were downregulated in placental tissues from women with severe PE compared with in those from controls. A Transwell invasion assay and wound healing assay revealed that overexpression of FAM99A promoted invasion and migration of HTR‑8/SVneo cells; conversely, knockdown of FAM99A suppressed the invasive and migratory abilities of HTR‑8/SVneo cells. Flow cytometry demonstrated that FAM99A overexpression induced a decrease in the apoptotic rate of cells, whereas knockdown of FAM99A increased the apoptotic rate of HTR‑8/SVneo cells. Western blot analysis revealed that overexpression of FAM99A decreased the protein expression levels of cleaved caspase‑3, cleaved caspase‑9 and Bax, and increased Bcl‑2 protein expression, whereas knockdown of FAM99A had the opposite effects on these protein levels. Overexpression of FAM99A also decreased caspase‑3 activity in HTR‑8/SVneo cells; however, knockdown of FAM99A increased caspase‑3 activity. In addition, overexpression of FAM99A enhanced Wnt/β‑catenin signaling activity, whereas FAM99A knockdown exerted an inhibitory effect on the Wnt/β‑catenin signaling activity in HTR‑8/SVneo cells. In conclusion, these results indicated that FAM99A may serve a role in modulating the functions of trophoblasts, partially via targeting Wnt/β‑catenin signaling.

Clinical Significance of Transcription Factor 7 (TCF7) as a Prognostic Factor in Gastric Cancer

Background

Transcription factor 7 (TCF7) plays an essential role in Wnt signaling by interacting with β-catenin. Emerging evidence demonstrates that overexpression of TCF7 promotes progression or correlates with poor progression in several types of cancers, but the functions of TCF7 in gastric cancer (GC) have not been revealed.

Material/Methods

A total of 168 patients with GC who underwent radical surgeries were collected and regarded as the test cohort. The expression of TCF7 in the 168 patients was detected with immunohistochemistry. Moreover, the mRNA levels of TCF7 in 11 pairs of GC and adjacent tissues were detected with quantitative real-time PCR (qRT-PCR). The correlations between TCF7 and the clinicopathological factors were evaluated with the chi-square test, and the prognostic value of TCF7 in GC was investigated with univariate analysis and multivariate analysis.

Results

The mRNA levels of TCF7 in GC tissues were significantly higher than in corresponding tumor adjacent tissues. The patients of low TCF7 expression and high TCF7 expression accounted for 76.79% (129/168) and 23.21% (39/168), respectively. In our experiments, TCF7 was significantly associated with positive lymphatic invasion (P=0.022) and metastasis (P<0.001). The high expression of TCF7 was correlated with low survival rates (P=0.012) and was confirmed as an independent prognostic factor (HR=1.92, 95%CI =1.06–3.47, P=0.031) of GC in multivariate analysis.

Conclusions

TCF7 expression is correlated with metastasis and is an independent prognostic factor of GC. TCF7 detection of GC could help stratify the patients with high risk and guide precise treatment.

Magnifying glass on spiradenoma and cylindroma histogenesis and tumorigenesis using systematic transcriptome analysis

Spiradenoma and cylindroma are related sweat gland tumors. To delineate their histogenesis, gene profiles, and their potential drivers, we performed a whole-transcriptome sequencing analysis of fourteen samples of spiradenoma/cylindroma in comparison to normal samples. A total of 12 spiradenomas, 5 cylindromas, 3 hybrid spiradenomas/cylindromas and 2 adnexal carcinomas were included in this study. 1335 characteristic genes and transcripts expressed over all 14 spiradenoma/cylindroma tumors were identified, and two groups of expression profiles were observed. Highest upregulated top 7 gene signatures characterized benign tumors with developmental and differentiation related genes, and carcinomas with top 7 genes mainly related to signaling, reorganization and metabolism of membranes. Immunohistochemistry of protein expressions validated 4 upregulated genes (ODAM, HOXB13, MYB and SOX10) considered important and as potential biomarkers for spiradenomas and cylindromas. We further compared the transcriptome of eccrine adnexal tumors with the transcriptome of adenoid cystic carcinoma (ACC) to identify the overlapping genes that may indicate histogenesis. There were 36 specific genes overlapping between adnexal carcinomas and the epithelial-dominant subtype of ACC, and 27 specific genes overlapping benign adnexal tumors with the myoepithelial-dominant subtype of ACC, At this point there is no known specific biomarker to aid in the diagnosis of eccrine spiradenoma and cylindroma in small samples or biopsies within the context of morphological overlap with ACC. In conclusion, spiradenomas and cylindromas are characterized by overexpressed developmental genes, where LHX2 and activated WNT signaling possibly drive associated carcinomas.

Molecular markers for corneal epithelial cells in larval vs. adult Xenopus frogs

Corneal Epithelial Stem Cells (CESCs) and their proliferative progeny, the Transit Amplifying Cells (TACs), are responsible for maintaining the integrity and transparency of the cornea. These stem cells (SCs) are widely used in corneal transplants and ocular surface reconstruction. Molecular markers are essential to identify, isolate and enrich for these cells, yet no definitive CESC marker has been established. An extensive literature survey shows variability in the expression of putative CESC markers among vertebrates; being attributed to species-specific variations, or other differences in developmental stages of these animals, approaches used in these studies and marker specificity. Here, we expanded the search for CESC markers using the amphibian model Xenopus laevis. In previous studies we found that long-term label retaining cells (suggestive of CESCs and TACs) are present throughout the larval basal corneal epithelium. In adult frogs, these cells become concentrated in the peripheral cornea (limbal region). Here, we used immunofluorescence to characterize the expression of nine proteins in the corneas of both Xenopus larvae and adults (post-metamorphic). We found that localization of some markers change between larval and adult stages. Markers such as p63, Keratin 19, and β1-integrin are restricted to basal corneal epithelial cells of the larvae. After metamorphosis their expression is found in basal and intermediate layer cells of the adult frog corneal epithelium. Another protein, Pax6 was expressed in the larval corneas, but surprisingly it was not detected in the adult corneal epithelium. For the first time we report that Tcf7l2 can be used as a marker to differentiate cornea vs. skin in frogs. Tcf7l2 is present only in the frog skin, which differs from reports indicating that the protein is expressed in the human cornea. Furthermore, we identified the transition between the inner, and the outer surface of the adult frog eyelid as a key boundary in terms of marker expression. Although these markers are useful to identify different regions and cellular layers of the frog corneal epithelium, none is unique to CESCs or TACs. Our results confirm that there is no single conserved CESC marker in vertebrates. This molecular characterization of the Xenopus cornea facilitates its use as a vertebrate model to understand the functions of key proteins in corneal homeostasis and wound repair.

Proteasomal deubiquitinase UCH37 inhibits degradation of β-catenin and promotes cell proliferation and motility

The ubiquitin-proteasome system degrades most cellular proteins in eukaryotes. UCH37, also known as UCH-L5, is a deubiquitinase binding to Rpn13, a receptor for ubiquitinated substrates in the 26 S proteasome. But, it remains unclear how UCH37 influences the proteasomal degradation of the ubiquitinated substrates. Because deletion of UCH37 is embryonically lethal in mice, this study aims to investigate the role of UCH37 in proteasomal degradation by constructing the UCH37-deficient cell lines using CRISPR/Cas9 technology. Our results demonstrated that deletion of UCH37 decreased the levels of proteasomal Rpn13, implying that UCH37 might facilitate incorporation of Rpn13 into the proteasome. Meanwhile, deletion of UCH37 decreased the levels of β-catenin and the early endosomal protein Rab8. β-Catenin interacts with TCF/LEF to control transcription, and is involved in development, tissue homeostasis and tumorigenesis. We further found that deletion of UCH37 increased the levels of the ubiquitinated β-catenin and accelerated the hydrogen peroxide-stimulated degradation of β-catenin. Deletion of UCH37 also down-regulated the transcription of c-Myc, a downstream effector of β-catenin, and inhibited cell proliferation and motility. These results raise the possibility that UCH37 maintains the homeostasis of proteasomal degradation reciprocally by assisting the recruitment of the ubiquitin receptor Rpn13 into the proteasome and by reversing ubiquitination of certain critical substrates of the 26 S proteasome.

Sostdc1 Regulates NK Cell Maturation and Cytotoxicity

NK cells are innate-like lymphocytes that eliminate virally infected and cancerous cells, but the mechanisms that control NK cell development and cytotoxicity are incompletely understood. We identified roles for sclerostin domain-containing-1 (Sostdc1) in NK cell development and function. Sostdc1-knockout (Sostdc1 ^-/-) mice display a progressive accumulation of transitional NK cells (tNKs) (CD27⁺CD11b⁺) with age, indicating a partial developmental block. The NK cell Ly49 repertoire in Sostdc1 ^-/- mice is also changed. Lower frequencies of Sostdc1 ^-/- splenic tNKs express inhibitory Ly49G2 receptors, but higher frequencies express activating Ly49H and Ly49D receptors. However, the frequencies of Ly49I⁺, G2⁺, H⁺, and D⁺ populations were universally decreased at the most mature (CD27^-CD11b⁺) stage. We hypothesized that the Ly49 repertoire in Sostdc1 ^-/- mice would correlate with NK killing ability and observed that Sostdc1^-/- NK cells are hyporesponsive against MHC class I-deficient cell targets in vitro and in vivo, despite higher CD107a surface levels and similar IFN-γ expression to controls. Consistent with Sostdc1's known role in Wnt signaling regulation, Tcf7 and Lef1 levels were higher in Sostdc1 ^-/- NK cells. Expression of the NK development gene Id2 was decreased in Sostdc1^-/- immature NK and tNK cells, but Eomes and Tbx21 expression was unaffected. Reciprocal bone marrow transplant experiments showed that Sostdc1 regulates NK cell maturation and expression of Ly49 receptors in a cell-extrinsic fashion from both nonhematopoietic and hematopoietic sources. Taken together, these data support a role for Sostdc1 in the regulation of NK cell maturation and cytotoxicity, and identify potential NK cell niches.

Role of β-Catenin Activation Levels and Fluctuations in Controlling Cell Fate

Cells have developed numerous adaptation mechanisms to external cues by controlling signaling-pathway activity, both qualitatively and quantitatively. The Wnt/β-catenin pathway is a highly conserved signaling pathway involved in many biological processes, including cell proliferation, differentiation, somatic cell reprogramming, development, and cancer. The activity of the Wnt/β-catenin pathway and the temporal dynamics of its effector β-catenin are tightly controlled by complex regulations. The latter encompass feedback loops within the pathway (e.g., a negative feedback loop involving Axin2, a β-catenin transcriptional target) and crosstalk interactions with other signaling pathways. Here, we provide a review shedding light on the coupling between Wnt/β-catenin activation levels and fluctuations across processes and cellular systems; in particular, we focus on development, in vitro pluripotency maintenance, and cancer. Possible mechanisms originating Wnt/β-catenin dynamic behaviors and consequently driving different cellular responses are also reviewed, and new avenues for future research are suggested.

A Comprehensive Analysis of Fibroblast Growth Factor Receptor 2b Signaling on Epithelial Tip Progenitor Cells During Early Mouse Lung Branching Morphogenesis

This study demonstrates that FGF10/FGFR2b signaling on distal epithelial progenitor cells, via ß-catenin/EP300, controls, through a comprehensive set of developmental genes, morphogenesis, and differentiation. Fibroblast growth factor (FGF) 10 signaling through FGF receptor 2b (FGFR2b) is mandatory during early lung development as the deletion of either the ligand or the receptor leads to lung agenesis. However, this drastic phenotype previously hampered characterization of the primary biological activities, immediate downstream targets and mechanisms of action. Through the use of a dominant negative transgenic mouse model (Rosa26rtTA; tet(o)sFgfr2b), we conditionally inhibited FGF10 signaling in vivo in E12.5 embryonic lungs via doxycycline IP injection to pregnant females, and in vitro by culturing control and experimental lungs with doxycycline. The impact on branching morphogenesis 9 h after doxycycline administration was analyzed by morphometry, fluorescence and electron microscopy. Gene arrays at 6 and 9 h following doxycycline administration were carried out. The relationship between FGF10 and ß-catenin signaling was also analyzed through in vitro experiments using IQ1, a pharmacological inhibitor of ß-catenin/EP300 transcriptional activity. Loss of FGF10 signaling did not impact proliferation or survival, but affected both adherens junctions (up-regulation of E-cadherin), and basement membrane organization (increased laminin). Gene arrays identified multiple direct targets of FGF10, including main transcription factors. Immunofluorescence showed a down-regulation of the distal epithelial marker SOX9 and mis-expression distally of the proximal marker SOX2. Staining for the transcriptionally-active form of ß-catenin showed a reduction in experimental vs. control lungs. In vitro experiments using IQ1 phenocopied the impacts of blocking FGF10. This study demonstrates that FGF10/FGFR2b signaling on distal epithelial progenitor cells via ß-catenin/EP300 controls, through a comprehensive set of developmental genes, cell adhesion, and differentiation.

TCF/LEF dependent and independent transcriptional regulation of Wnt/β-catenin target genes

During canonical Wnt signalling, the activity of nuclear β-catenin is largely mediated by the TCF/LEF family of transcription factors. To challenge this view, we used the CRISPR/Cas9 genome editing approach to generate HEK 293T cell clones lacking all four TCF/LEF genes. By performing unbiased whole transcriptome sequencing analysis, we found that a subset of β-catenin transcriptional targets did not require TCF/LEF factors for their regulation. Consistent with this finding, we observed in a genome-wide analysis that β-catenin occupied specific genomic regions in the absence of TCF/LEF Finally, we revealed the existence of a transcriptional activity of β-catenin that specifically appears when TCF/LEF factors are absent, and refer to this as β-catenin-GHOST response. Collectively, this study uncovers a previously neglected modus operandi of β-catenin that bypasses the TCF/LEF transcription factors.

Transcriptomic analysis of mRNA expression and alternative splicing during mouse sex determination

Mammalian sex determination hinges on sexually dimorphic transcriptional programs in developing fetal gonads. A comprehensive view of these programs is crucial for understanding the normal development of fetal testes and ovaries and the etiology of human disorders of sex development (DSDs), many of which remain unexplained. Using strand-specific RNA-sequencing, we characterized the mouse fetal gonadal transcriptome from 10.5 to 13.5 days post coitum, a key time window in sex determination and gonad development. Our dataset benefits from a greater sensitivity, accuracy and dynamic range compared to microarray studies, allows global dynamics and sex-specificity of gene expression to be assessed, and provides a window to non-transcriptional events such as alternative splicing. Spliceomic analysis uncovered female-specific regulation of Lef1 splicing, which may contribute to the enhanced WNT signaling activity in XX gonads. We provide a user-friendly visualization tool for the complete transcriptomic and spliceomic dataset as a resource for the field.

The Effects of the WNT-Signaling Modulators BIO and PKF118-310 on the Chondrogenic Differentiation of Human Mesenchymal Stem Cells

Mesenchymal stem cells (MSCs) are multipotent cells, mainly from bone marrow, and an ideal source of cells in bone and cartilage tissue engineering. A study of the chondrogenic differentiation of MSCs is of particular interest for MSCs-based cartilage regeneration. In this study, we aimed to optimize the conditions for the chrondogenic differentiation of MSCs by regulating WNT signaling using the small molecule WNT inhibitor PKF118-310 and activator BIO. Human mesenchymal stem cells (hMSCs) were isolated from bone marrow aspirates and cultured in hMSCs proliferation medium. Pellet culture was subsequently established for three-dimensional chondrogenic differentiation of 5 weeks. WNT signaling was increased by the small molecule glycogen synthase kinase-3 inhibitor 6-bromoindirubin-3-oxim (BIO) and decreased by the WNT inhibitor PKF118-310 (PKF). The effects of BIO and PKF on the chondrogenesis of hMSCs was examined by real-time PCR, histological methods, and ELISA. We found that activation of canonical WNT-signaling by BIO significantly downregulated the expression of cartilage-specific genes SOX9, COL2A1, and ACAN, and matrix metalloproteinase genes MMP1/3/9/13, but increased ADAMTS 4/5. Inhibition of WNT signaling by PKF increased the expression of SOX9, COL2A1, ACAN, and MMP9, but decreased MMP13 and ADAMTS4/5. In addition, a high level of WNT signaling induced the expression of hypertrophic markers COL10A1, ALPL, and RUNX2, the dedifferentiation marker COL1A1, and glycolysis genes GULT1 and PGK1. Deposition of glycosaminoglycan (GAG) and collagen type II in the pellet matrix was significantly lost in the BIO-treated group and increased in the PKF-treated group. The protein level of COL10A1 was also highly induced in the BIO group. Interestingly, BIO decreased the number of apoptotic cells while PKF significantly induced apoptosis during chondrogenesis. The natural WNT antagonist DKK1 and the protein level of MMP1 in the pellet culture medium were decreased after PKF treatment. All of these chondrogenic effects appeared to be mediated through the canonical WNT signaling pathway, since the target gene Axin2 and other WNT members, such as TCF4 and β-catenin, were upregulated by BIO and downregulated by PKF, respectively, and BIO induced nuclear translocation of β-catenin while PKF inhibited β-catenin translocation into the nucleus. We concluded that addition of BIO to a chondrogenic medium of hMSCs resulted in a loss of cartilage formation, while PKF induced chondrogenic differentiation and cartilage matrix deposition and inhibited hypertrophic differentiation. However, BIO promoted cell survival by inhibiting apoptosis while PKF induced cell apoptosis. This result indicates that either an overexpression or overinhibition of WNT signaling to some extent causes harmful effects on chondrogenic differentiation. Cartilage tissue engineering could benefit from the adjustment of the critical level of WNT signaling during chondrogenesis of hMSC.

MBD2 Ablation Impairs Lymphopoiesis and Impedes Progression and Maintenance of T-ALL

Aberrant DNA methylation patterns in leukemia might be exploited for therapeutic targeting. In this study, we employed a genetically deficient mouse model to explore the role of the methylated DNA binding protein MBD2 in normal and malignant hematopoiesis. MBD2 ablation led to diminished lymphocytes. Functional defects of the lymphoid compartment were also observed after in vivo reconstitution of MBD2-deficient hematopoietic stem cells (HSC). In an established model of Notch1-driven T-cell acute lymphoblastic leukemia (T-ALL), MBD2 ablation impeded malignant progression and maintenance by attenuating the Wnt signaling pathway. In clinical specimens of human T-ALL, Wnt signaling pathway signatures were significantly enhanced and positively correlated with the expression and function of MBD2. Furthermore, a number of typical Wnt signaling inhibitory genes were abnormally hypermethylated in primary human T-ALL. Abnormal activation of Wnt signaling in T-ALL was switched off by MBD2 deletion, partially by reactivating epigenetically silenced Wnt signaling inhibitors. Taken together, our results define essential roles for MBD2 in lymphopoiesis and T-ALL and suggest MBD2 as a candidate therapeutic target in T-ALL.Significance: This study highlights a methylated DNA binding protein as a candidate therapeutic target to improve the treatment of T-cell acute lymphoblastic leukemias, as a new starting point for developing epigenetic therapy in this and other lymphoid malignancies. Cancer Res; 78(7); 1632-42. ©2018 AACR.

Zanthoxylum avicennae extract enhances GSK-3β to attenuate β-catenin via phosphatase 2A to block metastatic effects of HA22T cells and hepatocellular carcinoma xenografted nude mice

Hepatocellular carcinoma (HCC) metastasis is often associated with the activation of Wnt/β-catenin signaling pathway. Zanthoxylum avicennae (Ying Bu Bo, YBB), a traditional herb with hepatoprotective effect, has been proven to inhibit human HCC in in vivo models however, the in vitro and in vivo effect of YBB on tumor metastasis is not clear yet. To determine whether YBB could inhibit HA22T human HCC cell by acting on β-catenin metastatic signaling in vitro and in vivo, HA22T cells were treated with different concentrations of YBB extracts (YBBE) and analyzed by Immunofluorescence staining assay, western blot analysis, siRNA mediated gene knock-down assays and co-immunoprecipitation assay. Additionally, the HA22T-implanted xenograft nude mice were used to confirm the assessed cellular effects. Mice treated with YBBEs showed a strong increasing trend in PP2Acα, GSK-3β, APC, and β-TrCP/HOS levels, however the expression of β-catenin, p-GSK-3β, TBX 3, and IL8 proteins showed a decreasing trend. YBBE significantly downregulated the nuclear and cytosolic β-catenin levels by facilitating the proteosomal degradation of β-catenin. Moreover, as observed by co-immunoprecipitation assay, YBBE directly promoted the protein interactions between GSK-3β, β-TrCP, APC, PP2A, and β-catenin. In conclusion, both in vitro and in vivo models clearly demonstrated that YBBE inhibits β-catenin involved metastatic signaling in highly metastatic HA22T cells through PP2A activation.

Heparan sulfate proteoglycans as key regulators of the mesenchymal niche of hematopoietic stem cells

The complex microenvironment that surrounds hematopoietic stem cells (HSCs) in the bone marrow niche involves different coordinated signaling pathways. The stem cells establish permanent interactions with distinct cell types such as mesenchymal stromal cells, osteoblasts, osteoclasts or endothelial cells and with secreted regulators such as growth factors, cytokines, chemokines and their receptors. These interactions are mediated through adhesion to extracellular matrix compounds also. All these signaling pathways are important for stem cell fates such as self-renewal, proliferation or differentiation, homing and mobilization, as well as for remodeling of the niche. Among these complex molecular cues, this review focuses on heparan sulfate (HS) structures and functions and on the role of enzymes involved in their biosynthesis and turnover. HS associated to core protein, constitute the superfamily of heparan sulfate proteoglycans (HSPGs) present on the cell surface and in the extracellular matrix of all tissues. The key regulatory effects of major medullar HSPGs are described, focusing on their roles in the interactions between hematopoietic stem cells and their endosteal niche, and on their ability to interact with Heparin Binding Proteins (HBPs). Finally, according to the relevance of HS moieties effects on this complex medullar niche, we describe recent data that identify HS mimetics or sulfated HS signatures as new glycanic tools and targets, respectively, for hematopoietic and mesenchymal stem cell based therapeutic applications.