PAX1 represses canonical Wnt signaling pathway and plays dual roles during endoderm differentiation.

BACKGROUND: Paired box 1 (PAX1) is a transcription factor and essential for the development of pharyngeal pouches-derived tissues, including thymus. PAX1 mutations are identified in Severe Combined Immunodeficiency (SCID) patients with Otofaciocervical Syndrome Type 2 (OTFCS2). However, despite the critical roles of PAX1 in embryonic development and diseases, detailed insights into its molecular mode of action are critically missing. METHODS: The repressing roles of PAX1 and SCID associated mutants on Wnt signaling pathway were investigated by luciferase reporter assays, qRT-PCR and in situ hybridization in HEK293FT, HCT116 cells and zebrafish embryos, respectively. Co-immunoprecipitation (co-IP) and western blotting assays were carried out to identify the molecular mechanisms underlying PAX1's role on Wnt signaling pathway. hESC based endoderm differentiation, flow cytometry, high-throughput sequencing data analysis, and qRT-PCR assays were utilized to determine the roles of PAX1 during endoderm differentiation. RESULTS: Here, we show that PAX1 represses canonical Wnt signaling pathway in vertebrate cells. Mechanically, PAX1 competes with SUMO E3 ligase PIASy to bind to TCF7L2, thus perturbing TCF7L2 SUMOylation level, further reducing its transcriptional activity and protein stability. Moreover, we reveal that PAX1 plays dual roles in hESC-derived definitive and foregut/pharyngeal endoderm cells, which give rise to the thymus epithelium, by inhibiting Wnt signaling. Importantly, our data show PAX1 mutations found in SCID patients significantly compromise the suppressing ability of PAX1 on Wnt signaling. CONCLUSIONS: Our study presents a novel molecular mode of action of PAX1 in regulation of canonical Wnt signaling and endoderm differentiation, thus providing insights for the molecular basis of PAX1 associated SCID, offering better understanding of the behavior of PAX1 in embryogenesis.

Wnt/ß-catenin signaling regulates amino acid metabolism through the suppression of CEBPA and FOXA1 in liver cancer cells.

Deregulation of the Wnt/ß-catenin pathway is associated with the development of human cancer including colorectal and liver cancer. Although we previously showed that histidine ammonia lyase (HAL) was transcriptionally reduced by the ß-catenin/TCF complex in liver cancer cells, the mechanism(s) of its down-regulation by the complex remain to be clarified. In this study, we search for the transcription factor(s) regulating HAL, and identify CEBPA and FOXA1, two factors whose expression is suppressed by the knockdown of ß-catenin or TCF7L2. In addition, RNA-seq analysis coupled with genome-wide mapping of CEBPA- and FOXA1-binding regions reveals that these two factors also increase the expression of arginase 1 (ARG1) that catalyzes the hydrolysis of arginine. Metabolome analysis discloses that activated Wnt signaling augments intracellular concentrations of histidine and arginine, and that the signal also increases the level of lactic acid suggesting the induction of the Warburg effect in liver cancer cells. Further analysis reveals that the levels of metabolites of the urea cycle and genes coding its related enzymes are also modulated by the Wnt signaling. These findings shed light on the altered cellular metabolism in the liver by the Wnt/ß-catenin pathway through the suppression of liver-enriched transcription factors including CEBPA and FOXA1.

BRD4-binding enhancer promotes CRC progression by interacting with YY1 to activate the Wnt pathway through upregulation of TCF7L2.

Colorectal carcinoma (CRC), one of the most life-threatening cancer types, is associated with aberrant expression of epigenetic modifiers and activation of the Wnt pathway. However, the role of epigenetic regulators in driving cancer cell proliferation and their potential as therapeutic targets affecting the Wnt pathway remain unclear. In this study, BRD4 was found to promote the progression of CRC both in vitro and in vivo. The expression of BRD4 correlated with shortened CRC patient survival. In addition, BRD4 function was strongly correlated with the Wnt pathway, but rather through regulation of TCF7L2 at transcriptional levels. BRD4 and H3K27ac have overlapping occupancies in the cis-regulatory elements of TCF7L2, suggesting enhancer-based epigenetic regulation. Numerous YY1 binding sites were found in the abovementioned region. YY1 recruited BRD4 to bind to cis-regulatory elements of TCF7L2, thereby regulating the expression of TCF7L2. Altogether, this study validates that BRD4 performs a canonical epigenetic regulatory function in CRC and can be used in the treatment of Wnt pathway-dependent CRC or other malignancies with clinically available bromodomain inhibitors.

The embryonic patterning gene Dbx1 governs the survival of the auditory midbrain via Tcf7l2-Ap2δ transcriptional cascade.

At the top of the midbrain is the inferior colliculus (IC), which functions as the major hub for processing auditory information. Despite the functional significance of neurons in the IC, our understanding of their formation is limited. In this study, we identify the embryonic patterning gene Dbx1 as a key molecular player that governs genetic programs for IC survival. We find that Dbx1 plays a critical role in preventing apoptotic cell death in postnatal IC by transcriptionally repressing c-Jun and pro-apoptotic BH3 only factors. Furthermore, by employing combined approaches, we uncover that Tcf7l2 functions downstream of Dbx1. Loss of Tcf7l2 function causes IC phenotypes with striking similarity to those of Dbx1 mutant mice, which include defective embryonic maturation and postnatal deletion of the IC. Finally, we demonstrate that the Dbx1-Tcf7l2 cascade functions upstream of Ap-2δ, which is essential for IC development and survival. Together, these results unravel a novel molecular mechanism for IC maintenance, which is indispensable for normal brain development.

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/ß-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 ß-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.

Tcf7l2 in hepatocytes regulates de novo lipogenesis in diet-induced non-alcoholic fatty liver disease in mice.

AIMS/HYPOTHESIS: Non-alcoholic fatty liver disease (NAFLD) associated with type 2 diabetes may more easily progress towards severe forms of non-alcoholic steatohepatitis (NASH) and cirrhosis. Although the Wnt effector transcription factor 7-like 2 (TCF7L2) is closely associated with type 2 diabetes risk, the role of TCF7L2 in NAFLD development remains unclear. Here, we investigated how changes in TCF7L2 expression in the liver affects hepatic lipid metabolism based on the major risk factors of NAFLD development. METHODS: Tcf7l2 was selectively ablated in the liver of C57BL/6N mice by inducing the albumin (Alb) promoter to recombine Tcf7l2 alleles floxed at exon 5 (liver-specific Tcf7l2-knockout [KO] mice: Alb-Cre;Tcf7l2f/f). Alb-Cre;Tcf7l2f/f and their wild-type (Tcf7l2f/f) littermates were fed a high-fat diet (HFD) or a high-carbohydrate diet (HCD) for 22 weeks to reproduce NAFLD/NASH. Mice were refed a standard chow diet or an HCD to stimulate de novo lipogenesis (DNL) or fed an HFD to provide exogenous fatty acids. We analysed glucose and insulin sensitivity, metabolic respiration, mRNA expression profiles, hepatic triglyceride (TG), hepatic DNL, selected hepatic metabolites, selected plasma metabolites and liver histology. RESULTS: Alb-Cre;Tcf7l2f/f essentially exhibited increased lipogenic genes, but there were no changes in hepatic lipid content in mice fed a normal chow diet. However, following 22 weeks of diet-induced NAFLD/NASH conditions, liver steatosis was exacerbated owing to preferential metabolism of carbohydrate over fat. Indeed, hepatic Tcf7l2 deficiency enhanced liver lipid content in a manner that was dependent on the duration and amount of exposure to carbohydrates, owing to cell-autonomous increases in hepatic DNL. Mechanistically, TCF7L2 regulated the transcriptional activity of Mlxipl (also known as ChREBP) by modulating O-GlcNAcylation and protein content of carbohydrate response element binding protein (ChREBP), and targeted Srebf1 (also called SREBP1) via miRNA (miR)-33-5p in hepatocytes. Eventually, restoring TCF7L2 expression at the physiological level in the liver of Alb-Cre;Tcf7l2f/f mice alleviated liver steatosis without altering body composition under both acute and chronic HCD conditions. CONCLUSIONS/INTERPRETATION: In mice, loss of hepatic Tcf7l2 contributes to liver steatosis by inducing preferential metabolism of carbohydrates via DNL activation. Therefore, TCF7L2 could be a promising regulator of the NAFLD associated with high-carbohydrate diets and diabetes since TCF7L2 deficiency may lead to development of NAFLD by promoting utilisation of excess glucose pools through activating DNL. DATA AVAILABILITY: RNA-sequencing data have been deposited into the NCBI GEO under the accession number GSE162449 ( www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE162449 ).

TCF7l2, a nuclear marker that labels premyelinating oligodendrocytes and promotes oligodendroglial lineage progression.

Clinical and basic neuroscience research is greatly benefited from the identification and characterization of lineage specific and developmental stage-specific markers. In the glial research community, histological markers that specifically label newly differentiated premyelinating oligodendrocytes are still scarce. Premyelinating oligodendrocyte markers, especially those of nuclear localization, enable researchers to easily quantify the rate of oligodendrocyte generation regardless of developmental ages. We propose that the transcription factor 7-like 2 (TCF7l2, mouse gene symbol Tcf7l2) is a useful nuclear marker that specifically labels newly generated premyelinating oligodendrocytes and promotes oligodendroglial lineage progression. Here, we highlight the controversial research history of TCF7l2 expression and function in oligodendroglial field and discuss previous experimental data justifying TCF7l2 as a specific nuclear marker for premyelinating oligodendrocytes during developmental myelination and remyelination. We conclude that TCF7l2 can be used alone or combined with pan-oligodendroglial lineage markers to identify newly differentiated or newly regenerated oligodendrocytes and quantify the rate of oligodendrocyte generation.

miR-212 Promotes Cardiomyocyte Hypertrophy through Regulating Transcription Factor 7 Like 2.

To explore the role and possible mechanism of miRNA-212 in heart failure (HF). The rat model of abdominal aortic constriction was constructed, the changes of myocardial morphology were observed by hematoxylin-eosin (HE) staining, and the hypertrophy-related marker molecules were detected by quantitative real-time polymerase chain reaction (qRT-PCR). At the cellular level, phenylephrine and angiotensin II were added to induce cardiomyocyte hypertrophy. The overexpression of miR-212 adenovirus was constructed, and the expression of miR-212 was overexpressed, and its effect on cardiac hypertrophy (CH) was detected by immunofluorescence and qRT-PCR. Then, the mechanism of miR-212 regulating CH was verified by website prediction, luciferase reporter gene assay, qRT-PCR, and western blotting assay. In the successfully constructed rat model of abdominal aortic constriction and cardiomyocyte hypertrophy, ANP and myh7 were dramatically increased, myh6 expression was decreased, and miRNA-212 expression was increased. Overexpression of miRNA-212 in cardiomyocytes can promote cardiomyocyte hypertrophy, while knocking down miR-212 in cardiomyocytes can partially reverse cell hypertrophy. In addition, miR-212 targets TCF7L2 and inhibits the expression of this gene. miRNA-212 targets TCF7L2 and inhibits the expression of this gene, possibly through this pathway to promote cardiomyocyte hypertrophy.

The positive regulatory loop of TCF4N/p65 promotes glioblastoma tumourigenesis and chemosensitivity.

BACKGROUND: NF-κB signaling is widely linked to the pathogenesis and treatment resistance in cancers. Increasing attention has been paid to its anti-oncogenic roles, due to its key functions in cellular senescence and the senescence-associated secretory phenotype (SASP). Therefore, thoroughly understanding the function and regulation of NF-κB in cancers is necessary prior to the application of NF-κB inhibitors. METHODS: We established glioblastoma (GBM) cell lines expressing ectopic TCF4N, an isoform of the ß-catenin interacting transcription factor TCF7L2, and evaluated its functions in GBM tumorigenesis and chemotherapy in vitro and in vivo. In p65 knock-out or phosphorylation mimic (S536D) cell lines, the dual role and correlation of TCF4N and NF-κB signaling in promoting tumorigenesis and chemosensitivity was investigated by in vitro and in vivo functional experiments. RNA-seq and computational analysis, immunoprecipitation and ubiquitination assay, minigene splicing assay and luciferase reporter assay were performed to identify the underlying mechanism of positive feedback regulation loop between TCF4N and the p65 subunit of NF-κB. A eukaryotic cell-penetrating peptide targeting TCF4N, 4N, was used to confirm the therapeutic significance. RESULTS: Our results indicated that p65 subunit phosphorylation at Ser 536 (S536) and nuclear accumulation was a promising prognostic marker for GBM, and endowed the dual functions of NF-κB in promoting tumorigenesis and chemosensitivity. p65 S536 phosphorylation and nuclear stability in GBM was regulated by TCF4N. TCF4N bound p65, induced p65 phosphorylation and nuclear translocation, inhibited its ubiquitination/degradation, and subsequently promoted NF-κB activity. p65 S536 phosphorylation was essential for TCF4N-led senescence-independent SASP, GBM tumorigenesis, tumor stem-like cell differentiation and chemosensitivity. Activation of p65 was closely connected to alterative splicing of TCF4N, a likely positive feedback regulation loop between TCF4N and p65 in GBM. 4N increased chemosensitivity, highlighting a novel anti-cancer strategy. CONCLUSION: Our study defined key roles of TCF4N as a novel regulator of NF-κB through mutual regulation with p65 and provided a new avenue for GBM inhibition.

A TCF7L2-responsive suppression of both homeostatic and compensatory remyelination in Huntington disease mice.

Huntington's disease (HD) is characterized by defective oligodendroglial differentiation and white matter disease. Here, we investigate the role of oligodendrocyte progenitor cell (OPC) dysfunction in adult myelin maintenance in HD. We first note a progressive, age-related loss of myelin in both R6/2 and zQ175 HD mice compared with wild-type controls. Adult R6/2 mice then manifest a significant delay in remyelination following cuprizone demyelination. RNA-sequencing and proteomic analysis of callosal white matter and OPCs isolated from both R6/2 and zQ175 mice reveals a systematic downregulation of genes associated with oligodendrocyte differentiation and myelinogenesis. Gene co-expression and network analysis predicts repressed Tcf7l2 signaling as a major driver of this expression pattern. In vivo Tcf7l2 overexpression restores both myelin gene expression and remyelination in demyelinated R6/2 mice. These data causally link impaired TCF7L2-dependent transcription to the poor development and homeostatic retention of myelin in HD and provide a mechanism for its therapeutic restoration.

FOXO1 differentially regulates bone formation in young and aged mice.

It is a great challenge to develop a safe and effective treatment strategy for age-related osteoporosis and fracture healing. As one of the four FOXO transcription factors, FOXO1 is essential for cell proliferation, survival, senescence, energy metabolism, and oxidative stress in various cells. Our previous study demonstrated that specific Foxo1 gene deletion in osteoblasts in young mice results in bone loss while that in aged mice shows the opposite effect. However, the mechanism underlying the differential regulation of bone metabolism by FOXO1 remains to be elucidated. In this study, we generated osteoblast-specific Foxo1 knockout mice by using Foxo1fl/fl and Bglap-Cre mice. In young mice, Foxo1 gene deletion inhibits osteoblast differentiation, leading to a decreased osteoblast number and decreased bone formation rate because of the weakened ability to resist oxidative stress, eventually resulting in bone loss and delayed healing of bone defects. In aged mice, high levels of reactive oxygen species (ROS) promote the diversion of CTNNB1 (ß-catenin) from T cell factor 4 (TCF4)- to FOXO1-mediated transcription, thereby inhibiting Wnt/ß-catenin signaling and leading to decreased osteogenic activity. Conversely, FOXO1 deficiency indirectly promotes the binding of ß-catenin and TCF4 and activates Wnt/ß-catenin signaling, thereby alleviating age-related bone loss and improving bone defect healing. Our study proves that FOXO1 has differential effects on bone metabolism in young and aged mice and elucidates its underlying mechanism. Further, this study provides a new perspective on the treatment of age-related osteoporosis.

Ubiquitin-specific protease 28 deubiquitinates TCF7L2 to govern the action of the Wnt signaling pathway in hepatic carcinoma.

Overexpression of ubiquitin-specific protease 28 (USP28) is found in hepatic carcinoma. It is unclear whether the deubiquitinase plays a role in hepatocarcinogenesis. Deregulation of the Wnt signaling pathway is frequently associated with liver cancer. Transcription factor 7-like 2 (TCF7L2) is an important downstream transcription factor of the Wnt/ß-catenin signaling pathway, but the mechanisms by which TCF7L2 itself is regulated have not yet been revealed. Here, we report that USP28 promotes the activity of the Wnt signaling pathway through maintaining the stability of TCF7L2. We further show that FBXW7 is the E3 ubiquitin ligase for TCF7L2. By regulating the levels of TCF7L2, USP28 modulates the Wnt/ß-catenin signaling in liver cancer and USP28 depletion or inhibition by a small molecule inhibitor leads to a halt of growth in liver cancer cells. These results suggest that USP28 could be a potential therapeutic target for liver cancer.

ALS-linked KIF5A ΔExon27 mutant causes neuronal toxicity through gain-of-function.

Mutations in the human kinesin family member 5A (KIF5A) gene were recently identified as a genetic cause of amyotrophic lateral sclerosis (ALS). Several KIF5A ALS variants cause exon 27 skipping and are predicted to produce motor proteins with an altered C-terminal tail (referred to as ΔExon27). However, the underlying pathogenic mechanism is still unknown. Here, we confirm the expression of KIF5A mutant proteins in patient iPSC-derived motor neurons. We perform a comprehensive analysis of ΔExon27 at the single-molecule, cellular, and organism levels. Our results show that ΔExon27 is prone to form cytoplasmic aggregates and is neurotoxic. The mutation relieves motor autoinhibition and increases motor self-association, leading to drastically enhanced processivity on microtubules. Finally, ectopic expression of ΔExon27 in Drosophila melanogaster causes wing defects, motor impairment, paralysis, and premature death. Our results suggest gain-of-function as an underlying disease mechanism in KIF5A-associated ALS.

TCF7L2 promotes ER stress signaling in diabetic retinopathy.

Diabetic retinopathy (DR) is one of the most common blindness in working-age adults. Transcription factor 7 like 2 (TCF7L2) is a susceptibility gene of DR, however, its roles in the pathogenesis of DR are still largely unknown. In this study, we found that TCF7L2 was mainly located in the cell nucleus of retinal ganglion cell layer (GCL) and inner nuclear layer (INL), while it was not expressed in the cell nucleus of retinal outer nuclear layer (ONL). Expression of TCF7L2 was significantly elevated in the retinas of db/db diabetic mice and oxygen-induced retinopathy (OIR) mice. Also, in Ad-hTCF7L2 treated hiPSCs-derived retinal progenitor cells (RPCs), activating transcription factor 6 (ATF6)-related endoplasmic reticulum (ER) stress signaling was remarkably activated. Moreover, knockdown of TCF7L2 significantly inhibited ATF6-related ER stress signaling. Furthermore, the data of endothelial permeability assay showed that RPCs pretreated with Ad-hTCF7L2 lead to enhanced monolayer permeability of human umbilical vein endothelial cells (HUVECs), and knockdown of TCF7L2 or ATF6 in RPCs could alleviate the monolayer permeability of HUVECs. Thus, our results showed that TCF7L2 could trigger ATF6-related ER stress signaling and promote vein endothelial cell permeability, which will provide important insight into the role of TCF7L2 in the pathogenesis of DR and contribute to designing potential therapies.

TCF7L2 plays a complex role in human adipose progenitor biology, which might contribute to genetic susceptibility to type 2 diabetes.

INTRODUCTION: Non-coding genetic variation at TCF7L2 is the strongest genetic determinant of type 2 diabetes (T2D) risk in humans. TCF7L2 encodes a transcription factor mediating the nuclear effects of WNT signaling in adipose tissue (AT). In vivo studies in transgenic mice have highlighted important roles for TCF7L2 in adipose tissue biology and systemic metabolism. OBJECTIVE: To map the expression of TCF7L2 in human AT, examine its role in human adipose cell biology in vitro, and investigate the effects of the fine-mapped T2D-risk allele at rs7903146 on AT morphology and TCF7L2 expression. METHODS: Ex vivo gene expression studies of TCF7L2 in whole and fractionated human AT. In vitro TCF7L2 gain- and/or loss-of-function studies in primary and immortalized human adipose progenitor cells (APCs) and mature adipocytes (mADs). AT phenotyping of rs7903146 T2D-risk variant carriers and matched controls. RESULTS: Adipose progenitors (APs) exhibited the highest TCF7L2 mRNA abundance compared to mature adipocytes and adipose-derived endothelial cells. Obesity was associated with reduced TCF7L2 transcript levels in whole subcutaneous abdominal AT but paradoxically increased expression in APs. In functional studies, TCF7L2 knockdown (KD) in abdominal APs led to dose-dependent activation of WNT/ß-catenin signaling, impaired proliferation and dose-dependent effects on adipogenesis. Whilst partial KD enhanced adipocyte differentiation, near-total KD impaired lipid accumulation and adipogenic gene expression. Over-expression of TCF7L2 accelerated adipogenesis. In contrast, TCF7L2-KD in gluteal APs dose-dependently enhanced lipid accumulation. Transcriptome-wide profiling revealed that TCF7L2 might modulate multiple aspects of AP biology including extracellular matrix secretion, immune signaling and apoptosis. The T2D-risk allele at rs7903146 was associated with reduced AP TCF7L2 expression and enhanced AT insulin sensitivity. CONCLUSIONS: TCF7L2 plays a complex role in AP biology and has both dose- and depot-dependent effects on adipogenesis. In addition to regulating pancreatic insulin secretion, genetic variation at TCF7L2 might also influence T2D risk by modulating AP function.

T-cell factor 7L2 is a novel regulator of osteoblast functions that acts in part by modulation of hypoxia signaling.

T-cell-like factor (TCF)7l2, a key effector of canonical Wnt signaling, is highly expressed in bone but nothing is known about its role in regulating osteoblast function. To test this, we generated mice with conditional disruption of Tcf7l2 gene in osteoblast lineages using Tcf7l2 floxed and Col1α2-Cre mice. Skeletal parameters were evaluated using heterozygous conditional knockdown (HCKD) mice since homozygous conditional knockout died during pregnancy or immediately after birth. At 5 wk of age, trabecular bone mass of long bones was reduced by 35% as measured by microcomputed tomography (µCT). Histology data showed a 42% reduction in femur trabecular bone mass caused by reduced bone formation. Knockdown of Tcf7l2 expression in osteoblasts decreased proliferation and differentiation by 20%-40%. Expression levels of genes (Hif1α, Vegf, and ß-catenin) targeted by TCF7L2 were decreased by 50% in Tcf7l2-deficient osteoblasts and bones of HCKD mice. We found that the Hif1α gene promoter contained multiple putative TCF7L2 motifs and stabilization of HIF1α protein levels rescued expression of TCF7L2 target genes and alkaline phosphatase (ALP) activity in Tcf7l2-deficient osteoblasts. Furthermore, Tcf7l2 overexpression increased proliferation in the presence of canonical Wnt3a that was not affected by ß-catenin inhibitor providing evidence for a noncanonical signaling in mediating TCF7L2 effects. Tcf7l2 expression was increased in response to mechanical strain (MS) in vitro and in vivo, and disruption of Tcf7l2 expression in osteoblasts reduced MS-induced ALP activity by 35%. We conclude that Tcf7l2, a mechanoresponsive gene, is an important regulator of osteoblast function acting, in part, via hypoxia signaling.NEW & NOTEWORTHY TCF7L2 is expressed by bone but it was not known whether TCF7L2 expression influenced bone development. By using a mouse model with conditional disruption of Tcf7l2 in osteoblast lineage cells, we have demonstrated for the first time, that TCF7L2 plays an important role in regulating osteoblasts via a noncanonical pathway.

Activation of WNT/CTNNB1/TCF7L2 in Epstein-Barr virus-positive gastric cancer regulates epithelial mesenchymal transition.

Gastric cancer (GC) is the fifth most frequently diagnosed malignant tumour and the third leading cause of cancer-related death. EBV infection is one of the major causes of GC, accounting for approximately 10% of GC cases. Studies revealed that EBV infection could induce malignancy through multilevel mechanisms, including epigenetics state alterations, miRNA regulations, etc. However, it is poorly understood if EBV positive GC has any characteristic oncogenic singling activation. By comparing the transcriptomic of EB positive and negative cell lines, TCGA GC samples, and GC single cells, we identified that canonical WNT signalling is commonly activated in EBV positive GC. Next, we proved that the WNT activation is crucial for the invasiveness of the GC via regulating epithelial-mesenchymal transition (EMT) gene expressions. Then we confirmed that the WNT signalling activation in EBV + GC is through the WNT/CTNNB1 (ß-catenin)/TCF7L2 axis with the expression of TCF7L2 indicating worse outcome and more metastasis in EBV+ GCs. Finally, we found that KLF5 is potentially involved as a cooperative transcription factor in the early phase of the EMT process through single-cell pseudotime analysis.

Matrine inhibits the Wnt3a/ß-catenin/TCF7L2 signaling pathway in experimental autoimmune encephalomyelitis.

Oligodendrocyte (OL) death and remyelination failure lead to progressive neurological deficits in multiple sclerosis (MS) and its animal model, experimental autoimmune encephalomyelitis (EAE). Matrine (MAT), a quinolizidine alkaloid component derived from the root of Sophora flavescens, has the capacity to effectively inhibit central nervous system (CNS) inflammation and to promote neuroregeneration. In the present study we explored its regulatory mechanism on the Wnt/ß-catenin/TCF7L2 pathway, a negative modulator for myelination, in MOG35--55 peptide-induced EAE. Our results clearly indicate that MAT treatment reduced the activation of Wnt3a and ß-catenin in the CNS of EAE mice, accompanied by the activation of GSK3ß and decreased expression of cyclin D1 and Axin2, two target genes of the Wnt3a/ß-catenin pathway. In addition, MAT increased OL maturation and myelination, as evidenced by the decreased number of NG2+Olig2+ cells and the increased numbers of MBP+ and CC1+Olig2+ cells. Taken together, these findings indicate that MAT treatment promoted the maturation of OLs and myelin repair, which is closely related to the modulation of the Wnt/ß-catenin/TCF7L2 signaling pathway.

Interaction of lncRNA MIR100HG with hnRNPA2B1 facilitates m6A-dependent stabilization of TCF7L2 mRNA and colorectal cancer progression.

BACKGROUND: Epithelial-to-mesenchymal transition (EMT) is a process linked to metastasis and drug resistance with non-coding RNAs (ncRNAs) playing pivotal roles. We previously showed that miR-100 and miR-125b, embedded within the third intron of the ncRNA host gene MIR100HG, confer resistance to cetuximab, an anti-epidermal growth factor receptor (EGFR) monoclonal antibody, in colorectal cancer (CRC). However, whether the MIR100HG transcript itself has a role in cetuximab resistance or EMT is unknown. METHODS: The correlation between MIR100HG and EMT was analyzed by curating public CRC data repositories. The biological roles of MIR100HG in EMT, metastasis and cetuximab resistance in CRC were determined both in vitro and in vivo. The expression patterns of MIR100HG, hnRNPA2B1 and TCF7L2 in CRC specimens from patients who progressed on cetuximab and patients with metastatic disease were analyzed by RNAscope and immunohistochemical staining. RESULTS: The expression of MIR100HG was strongly correlated with EMT markers and acted as a positive regulator of EMT. MIR100HG sustained cetuximab resistance and facilitated invasion and metastasis in CRC cells both in vitro and in vivo. hnRNPA2B1 was identified as a binding partner of MIR100HG. Mechanistically, MIR100HG maintained mRNA stability of TCF7L2, a major transcriptional coactivator of the Wnt/ß-catenin signaling, by interacting with hnRNPA2B1. hnRNPA2B1 recognized the N6-methyladenosine (m6A) site of TCF7L2 mRNA in the presence of MIR100HG. TCF7L2, in turn, activated MIR100HG transcription, forming a feed forward regulatory loop. The MIR100HG/hnRNPA2B1/TCF7L2 axis was augmented in specimens from CRC patients who either developed local or distant metastasis or had disease progression that was associated with cetuximab resistance. CONCLUSIONS: MIR100HG and hnRNPA2B1 interact to control the transcriptional activity of Wnt signaling in CRC via regulation of TCF7L2 mRNA stability. Our findings identified MIR100HG as a potent EMT inducer in CRC that may contribute to cetuximab resistance and metastasis by activation of a MIR100HG/hnRNPA2B1/TCF7L2 feedback loop.

S100A4/TCF Complex Transcription Regulation Drives Epithelial-Mesenchymal Transition in Chronic Sinusitis Through Wnt/GSK-3ß/ß-Catenin Signaling.

Epithelial-mesenchymal transition (EMT) is thought to be involved in the tissue remodeling and long-term inflammatory process of chronic sinusitis (CRS), but the driving mechanism is still unclear. Using high-resolution mass spectrometry, we performed a proteomic screen of CRS nasal mucosal tissue to identify differentially expressed proteins. Data are available via ProteomeXchange with identifier PXD030884. Specifically, we identified S100 calcium binding protein A4 (S100A4), an effective factor in inflammation-related diseases, and its downstream protein closely related to tissue fibrosis collagen type I alpha 1 chain (COL1A1), which suggested its involvement in nasal mucosal tissue remodeling. In addition, stimulation of human nasal epithelial cells (HNEpCs) with lipopolysaccharide (LPS) mimicked the inflammatory environment of CRS and showed that S100A4 is involved in regulating EMT and thus accelerating tissue remodeling in the nasal mucosa, both in terms of increased cell motility and overexpression of mesenchymal-type proteins. Additionally, we further investigated the regulation mechanism of S100A4 involved in EMT in CRS. Our research results show that in the inflammatory environment of CRS nasal mucosal epithelial cells, TCF-4 will target to bind to S100A4 and regulate its transcription. The transcription of S100A4 in turn affects the execution of the important signaling pathway in EMT, the Wnt/GSK-3ß/ß-catenin pathway, through the TCF-4/ß-catenin complex. In conclusion, this study confirmed that the expression of S100A4 was significantly increased during the progressive EMT process of CRS mucosal epithelial cells, and revealed that the transcriptional regulation of S100A4 plays an important role in the occurrence and development of EMT. This finding will help us to better understand the pathogenesis behind the remodeling in CRS patients, and identify target molecules for the treatment of CRS.