Catenins: keeping cells from getting their signals crossed

Effect of heat stress on ileal epithelial barrier integrity in broilers divergently selected for high- and low-water efficiency

Water scarcity and rising global temperatures are two of the greatest current and future threats to poultry sustainability. Therefore, selection for water efficiency (WE) and heat resilience are of vital importance. Additionally, intestinal integrity is of critical importance under challenging conditions to maintain nutrient absorption and therefore, growth and performance of broilers. Here, we examined the effect of chronic cyclic heat stress (HS) on the ileal expression profile of tight-junction, gap-junction, adherens, and desmosome genes in the fourth generation of divergently selected low (LWE)- and high water efficient (HWE)-chicken lines. LWE birds exhibited higher levels of gut permeability, regardless of temperature, as measured by fluorescein isothiocyanate-dextran (FITC-D). Among the claudins (CLDN), Cldn1 showed greater expression in the HWE as compared to LWE, regardless of temperature. Cldn5, -16, -20, and -34 genes were all greater in LWE and lower in HWE during HS. Conversely, Cldn25 was decreased in LWE but increased HWE under HS. Cldn4 was increased in the HWE line and decreased by HS. Cingulin (Cgn) gene expression was lower in HWE as compared to LWE and lower in HS as compared to thermoneutral (TN) condition. Gap junction protein α1 (Gja1) and desmoglein 4 (Dsg4) were greater in the HWE as compared to the LWE. Cadherin 1 (Cdh1) gene expression was greatest in the HWE in TN conditions and lowest in HWE under HS, whereas catenin α2 (Ctnna2) and desmocollin 1 (Dsc1) were highest in HWE during HS compared to all other groups. This differential expression of key genes associated with intestinal barrier integrity likely contributes to the water efficiency phenotype and the response of these birds to HS.

Intracellular pH regulates β-catenin with low pHi increasing adhesion and signaling functions

Intracellular pH (pHi) dynamics are linked to cell processes including proliferation, migration, and differentiation. The adherens junction (AJ) and signaling protein β-catenin has decreased abundance at high pHi due to increased proteasomal-mediated degradation. However, the effects of low pHi on β-catenin abundance and functions have not been characterized. Here, we show that low pHi stabilizes β-catenin in epithelial cells using population-level and single-cell assays. β-catenin abundance is increased at low pHi and decreased at high pHi. We also assay single-cell protein degradation rates to show that β-catenin half-life is longer at low compared to high pHi. Importantly, we show that AJs are not disrupted by β-catenin loss at high pHi due to rescue by plakoglobin. Finally, we show that low pHi increases β-catenin transcriptional activity in single cells and is indistinguishable from a Wnt-on state. This work characterizes pHi as a rheostat regulating β-catenin abundance, stability, and function and implicates β-catenin as a molecular mediator of pHi-dependent cell processes.

WNT enhancing signals in pancreatic cancer are transmitted by LGR6

The G-protein-coupled receptor LGR6 associates with ligands of the R-Spondin (RSPO) family to potentiate preexisting signals of the canonical WNT pathway. However, its importance in pancreatic ductal adenocarcinoma (PDAC) remains unclear. Here, we show that LGR6 is differentially expressed in various PDAC cell lines of mesenchymal and epithelial phenotype, respectively, siding with the latter subsets. LGR6 expression is altered based upon the cells' WNT activation status. Furthermore, extrinsic enhancement of WNT pathway signaling increased LGR6 expression suggestive of a reinforcing self-regulatory loop in highly WNT susceptible cells. Downregulation of LGR6 on the other hand, seemed to tamper those effects. Last, downregulation of LGR6 reduced cancer stemness as determined by functional in vitro assays. These findings shed new insights into regulatory mechanisms for the canonical WNT pathway in pancreatic cancer cells. It may also have potential value for treatment stratification of PDAC.

E-cadherin is a biomarker for ferroptosis sensitivity in diffuse gastric cancer

Gastric cancer is the third most common cause of cancer-related death worldwide. Diffuse-type gastric cancer (DGC) is a particularly aggressive subtype that is both difficult to detect and treat. DGC is distinguished by weak cell-cell cohesion, most often due to loss of the cell adhesion protein E-cadherin, a common occurrence in highly invasive, metastatic cancer cells. In this study, we demonstrate that loss-of-function mutation of E-cadherin in DGC cells results in their increased sensitivity to the non-apoptotic, iron-dependent form of cell death, ferroptosis. Homophilic contacts between E-cadherin molecules on adjacent cells suppress ferroptosis through activation of the Hippo pathway. Furthermore, single nucleotide mutations observed in DGC patients that ablate the homophilic binding capacity of E-cadherin reverse the ability of E-cadherin to suppress ferroptosis in both cell culture and xenograft models. Importantly, although E-cadherin loss in cancer cells is considered an essential event for epithelial-mesenchymal transition and subsequent metastasis, we found that circulating DGC cells lacking E-cadherin expression possess lower metastatic ability, due to their increased susceptibility to ferroptosis. Together, this study suggests that E-cadherin is a biomarker predicting the sensitivity to ferroptosis of DGC cells, both in primary tumor tissue and in circulation, thus guiding the usage of future ferroptosis-inducing therapeutics for the treatment of DGC.

Regulation of Physiological Barrier Function by the Commensal Microbiota

A fundamental characteristic of living organisms is their ability to separate the internal and external environments, a function achieved in large part through the different physiological barrier systems and their component junctional molecules. Barrier integrity is subject to multiple influences, but one that has received comparatively little attention to date is the role of the commensal microbiota. These microbes, which represent approximately 50% of the cells in the human body, are increasingly recognized as powerful physiological modulators in other systems, but their role in regulating barrier function is only beginning to be addressed. Through comparison of the impact commensal microbes have on cell-cell junctions in three exemplar physiological barriers-the gut epithelium, the epidermis and the blood-brain barrier-this review will emphasize the important contribution microbes and microbe-derived mediators play in governing barrier function. By extension, this will highlight the critical homeostatic role of commensal microbes, as well as identifying the puzzles and opportunities arising from our steadily increasing knowledge of this aspect of physiology.

Plakophilin 3 facilitates G1/S phase transition and enhances proliferation by capturing RB protein in the cytoplasm and promoting EGFR signaling

Plakophilin 3 (PKP3) is a component of desmosomes and is frequently overexpressed in cancer. Using keratinocytes either lacking or overexpressing PKP3, we identify a signaling axis from ERK to the retinoblastoma (RB) protein and the E2F1 transcription factor that is controlled by PKP3. RB and E2F1 are key components controlling G1/S transition in the cell cycle. We show that PKP3 stimulates the activity of ERK and its target RSK1. This inhibits expression of the transcription factor RUNX3, a positive regulator of the CDK inhibitor CDKN1A/p21, which is also downregulated by PKP3. Elevated CDKN1A prevents RB phosphorylation and E2F1 target gene expression, leading to delayed S phase entry and reduced proliferation in PKP3-depleted cells. Elevated PKP3 expression not only increases ERK activity but also captures phosphorylated RB (phospho-RB) in the cytoplasm to promote E2F1 activity and cell-cycle progression. These data identify a mechanism by which PKP3 promotes proliferation and acts as an oncogene.

Intestinal protein uptake and IgE-mediated food allergy

Food allergy is affecting 5-8% of young children and 2-4% of adults and seems to be increasing in prevalence. The cause of the increase in food allergy is largely unknown but proposed to be influenced by both environmental and lifestyle factors. Changes in intestinal barrier functions and increased uptake of dietary proteins have been suggested to have a great impact on food allergy. In this review, we aim to give an overview of the gastrointestinal digestion and intestinal barrier function and provide a more detailed description of intestinal protein uptake, including the various routes of epithelial transport, how it may be affected by both intrinsic and extrinsic factors, and the relation to food allergy. Further, we give an overview of in vitro, ex vivo and in vivo techniques available for evaluation of intestinal protein uptake and gut permeability in general. Proteins are digested by gastric, pancreatic and integral brush border enzymes in order to allow for sufficient nutritional uptake. Absorption and transport of dietary proteins across the epithelial layer is known to be dependent on the physicochemical properties of the proteins and their digestion fragments themselves, such as size, solubility and aggregation status. It is believed, that the greater an amount of intact protein or larger peptide fragments that is transported through the epithelial layer, and thus encountered by the mucosal immune system in the gut, the greater is the risk of inducing an adverse allergic response. Proteins may be absorbed across the epithelial barrier by means of various mechanisms, and studies have shown that a transcellular facilitated transport route unique for food allergic individuals are at play for transport of allergens, and that upon mediator release from mast cells an enhanced allergen transport via the paracellular route occurs. This is in contrast to healthy individuals where transcytosis through the enterocytes is the main route of protein uptake. Thus, knowledge on factors affecting intestinal barrier functions and methods for the determination of their impact on protein uptake may be useful in future allergenicity assessments and for development of future preventive and treatment strategies.

STK4 protein expression pattern follows different trends in endometrioid and serous endometrial adenocarcinoma upon tumor progression

In a previous study, we showed that serine/threonine-protein kinase 4 (STK4) is involved in the control on proliferation and migration of endometrial cancer (EC) cells in vitro. In the present paper, we studied STK4 expression in EC tissues from a large cohort of patients to determine whether STK4 can serve as a marker for the aggressiveness and prognosis of EC. Tissue samples from patients with EC were examined for tumor type, grade, and stage. The STK4 protein expression in EC cells was assessed by immunohistochemistry and related to clinicopathological data of patients, such as progression and patient survival rate. The STK4 mRNA levels and its relation to the survival rate were analyzed also in publicly available databases. The STK4 gene expression was low at both, the mRNA and protein levels in EC, especially in serous tumors. Comparison of STK4 expression with the patient survival rate shows that the higher expression is associated with worse prognosis in serous EC, while no such dependence was found in endometrioid EC. Hence, the determination of the SKT4 expression pattern could be used as a putative prognostic marker for serous EC.

Evolutionarily conserved gene expression patterns for affective disorders revealed using cross-species brain transcriptomic analyses in humans, rats and zebrafish

Widespread, debilitating and often treatment-resistant, depression and other stress-related neuropsychiatric disorders represent an urgent unmet biomedical and societal problem. Although animal models of these disorders are commonly used to study stress pathogenesis, they are often difficult to translate across species into valuable and meaningful clinically relevant data. To address this problem, here we utilized several cross-species/cross-taxon approaches to identify potential evolutionarily conserved differentially expressed genes and their sets. We also assessed enrichment of these genes for transcription factors DNA-binding sites down- and up- stream from their genetic sequences. For this, we compared our own RNA-seq brain transcriptomic data obtained from chronically stressed rats and zebrafish with publicly available human transcriptomic data for patients with major depression and their respective healthy control groups. Utilizing these data from the three species, we next analyzed their differential gene expression, gene set enrichment and protein-protein interaction networks, combined with validated tools for data pooling. This approach allowed us to identify several key brain proteins (GRIA1, DLG1, CDH1, THRB, PLCG2, NGEF, IKZF1 and FEZF2) as promising, evolutionarily conserved and shared affective 'hub' protein targets, as well as to propose a novel gene set that may be used to further study affective pathogenesis. Overall, these approaches may advance cross-species brain transcriptomic analyses, and call for further cross-species studies into putative shared molecular mechanisms of affective pathogenesis.

SRF: a seriously responsible factor in cardiac development and disease

The molecular mechanisms that regulate embryogenesis and cardiac development are calibrated by multiple signal transduction pathways within or between different cell lineages via autocrine or paracrine mechanisms of action. The heart is the first functional organ to form during development, which highlights the importance of this organ in later stages of growth. Knowledge of the regulatory mechanisms underlying cardiac development and adult cardiac homeostasis paves the way for discovering therapeutic possibilities for cardiac disease treatment. Serum response factor (SRF) is a major transcription factor that controls both embryonic and adult cardiac development. SRF expression is needed through the duration of development, from the first mesodermal cell in a developing embryo to the last cell damaged by infarction in the myocardium. Precise regulation of SRF expression is critical for mesoderm formation and cardiac crescent formation in the embryo, and altered SRF levels lead to cardiomyopathies in the adult heart, suggesting the vital role played by SRF in cardiac development and disease. This review provides a detailed overview of SRF and its partners in their various functions and discusses the future scope and possible therapeutic potential of SRF in the cardiovascular system.

Microscopic Visualization of Cell-Cell Adhesion Complexes at Micro and Nanoscale

Considerable progress has been made in our knowledge of the morphological and functional varieties of anchoring junctions. Cell-cell adhesion contacts consist of discrete junctional structures responsible for the mechanical coupling of cytoskeletons and allow the transmission of mechanical signals across the cell collective. The three main adhesion complexes are adherens junctions, tight junctions, and desmosomes. Microscopy has played a fundamental role in understanding these adhesion complexes on different levels in both physiological and pathological conditions. In this review, we discuss the main light and electron microscopy techniques used to unravel the structure and composition of the three cell-cell contacts in epithelial and endothelial cells. It functions as a guide to pick the appropriate imaging technique(s) for the adhesion complexes of interest. We also point out the latest techniques that have emerged. At the end, we discuss the problems investigators encounter during their cell-cell adhesion research using microscopic techniques.

Epithelial-mesenchymal transition, regulated by β-catenin and Twist, leads to esophageal wall remodeling in pediatric eosinophilic esophagitis

Eosinophilic Esophagitis (EoE) is an antigen-triggered inflammatory condition of the esophageal lining characterized by eosinophilic infiltration. EoE is associated with significant remodeling, and although this remodeling is reversed by current treatment regimens, symptoms of EoE and associated remodeling reappear upon cessation of therapies. We hypothesized that structural remodeling of cell-cell adhesion is a key factor in the pathogenesis of EoE and that epithelial to mesenchymal transition (EMT) was a viable molecular process to lead to this remodeling. Endoscopically obtained biopsy samples from 18 EoE and 18 control pediatric patients were evaluated by transmission electron microscopy to measure intercellular spaces (IS) between cells. Biopsy samples from all groups were analyzed for cellular levels of cell-cell adhesion proteins: E-cadherin, zonula occludens associated protein-1 (ZO-1), and N-cadherin. We also analyzed for cellular levels and localization two of transcription factors, Twist1 and β-catenin, that are associated with promoting EMT. The IS was significantly increased in the EoE group compared to the control. We observed a significant decrease in E-cadherin and ZO-1 levels and a concomitant increase in N-cadherin levels in EoE samples compared to control. Further, while there was no significant change in cellular levels of β-catenin, we observed an altered localization of the protein from the cell membrane in control tissue to a nuclear/perinuclear localization in EoE. We observed higher levels of the transcription factor Twist1 in the EoE group compared to normal which was localized mainly at the nucleus. Our results suggest that the integrity of normally sealed esophageal epithelia is compromised in the EoE patients compared to control subjects, and this is due to alterations in the expression of cell adhesion molecules at the esophageal epithelium. Our data also suggest that EMT, potentially regulated by transcription factors β-catenin and Twist1, may be responsible for the molecular alteration which leads to the remodeling of esophageal epithelia in EoE.

Satb2 Regulates EphA7 to Control Soma Spacing and Self-Avoidance of Cortical Pyramidal Neurons

Soma spacing and dendritic arborization during brain development are key events for the establishment of proper neural circuitry and function. Transcription factor Satb2 is a molecular node in regulating the development of the cerebral cortex, as shown by the facts that Satb2 is required for the regionalization of retrosplenial cortex, the determination of callosal neuron fate, and the regulation of soma spacing and dendritic self-avoidance of cortical pyramidal neurons. In this study, we explored downstream effectors that mediate the Satb2-implicated soma spacing and dendritic self-avoidance. First, RNA-seq analysis of the cortex revealed differentially expressed genes between control and Satb2 CKO mice. Among them, EphA7 transcription was dramatically increased in layers II/III of Satb2 CKO cortex. Overexpression of EphA7 in the late-born cortical neurons of wild-type mice via in utero electroporation resulted in soma clumping and impaired self-avoidance of affected pyramidal neurons, which resembles the phenotypes caused by knockdown of Satb2 expression. Importantly, the phenotypes by Satb2 knockdown was rescued by reducing EphA7 expression in the cortex. Finally, ChIP and luciferase reporter assays indicated a direct suppression of EphA7 expression by Satb2. These findings provide new insights into the complexity of transcriptional regulation of the morphogenesis of cerebral cortex.

[E-cadherin expression in tumor emboli in gastric cancer]

OBJECTIVE

To determine the level of E-cadherin expression in tumor emboli, to compare it with expression in a tumor, to determine the dependence of E-cadherin expression in tumor emboli on the clinical and morphological characteristics of gastric cancer.

MATERIAL AND METHODS

We used samples of surgical material from 280 patients with a verified diagnosis of gastric cancer. E-cadherin expression was determined by immunohistochemical method. The results of the reactions were assessed semi-quantitatively and compared with the main clinical and morphological characteristics of gastric cancer (histological type according to the WHO classification 2019, histological type according to the classification of P. Lauren, clinical stage, depth of invasion (T), number of metastases in lymph nodes (N), presence or/absence of distant metastases (M), tumor localization in the stomach).

RESULTS

Among 280 cases of cancer, emboli were detected only in 67 cases, used for further analysis. The rest of the samples were excluded from the analysis, since emboli did not get into the sections during the cutting of immunohistochemical preparations. The expression of E-cadherin in tumor emboli was significantly higher (p<0.001) than in tumor tissue. At the same time, no cases identified where the level of E-cadherin decreased in emboli compared to the tumor. A significant increase in the expression of E-cadherin in tumor emboli compared to the primary tumor was noted for all histological types according to WHO 2019, for intermediate and diffuse types according to the P. Lauren classification (p<0.001). Comparison of expression in emboli and tumors for neoplasms with different depths of invasion (T), different stages and different localizations did not reveal statistically significant differences. An increase in the expression of E-cadherin in emboli compared to tumors was characterized by a higher level of significance in the presence of metastases (N1, N2, N3a, N3b; p<0.001) than in the absence of metastases (N0; p=0.016).

CONCLUSION

The study revealed a statistically significant increase in the expression of E-cadherin in tumor emboli compared to the primary tumor, which is evidence of its important role in maintaining the integrity of emboli and tumor dissemination.

Targeted intestinal deletion of Rho guanine nucleotide exchange factor 7, βPIX, impairs enterocyte proliferation, villus maturation, and mucosal defenses in mice

Rho guanine nucleotide exchange factors (RhoGEFs) regulate Rho GTPase activity and cytoskeletal and cell adhesion dynamics. βPix, a CDC42/RAC family RhoGEF encoded by ARHGEF7, is reported to modulate human colon cancer cell proliferation and postwounding restitution of rat intestinal epithelial monolayers. We hypothesized that βPix plays a role in maintaining intestinal epithelial homeostasis. To test this hypothesis, we examined βPix distribution in the human and murine intestine and created mice with intestinal epithelial-selective βPix deletion [βPixflox/flox/Tg(villin-Cre); Arhgef7 CKO mice]. Using Arhgef7 conditional knockout (CKO) and control mice, we investigated the consequences of βPix deficiency in vivo on intestinal epithelial and enteroid development, dextran sodium sulfate-induced mucosal injury, and gut permeability. In normal human and murine intestines, we observed diffuse cytoplasmic and moderate nuclear βPix immunostaining in enterocytes. Arhgef7 CKO mice were viable and fertile, with normal gross intestinal architecture but reduced small intestinal villus height, villus-to-crypt ratio, and goblet cells; small intestinal crypt cells had reduced Ki67 staining, compatible with impaired cell proliferation. Enteroids derived from control mouse small intestine were viable for more than 20 passages, but those from Arhgef7 CKO mice did not survive beyond 24 h despite addition of Wnt proteins or conditioned media from normal enteroids. Adding a Rho kinase (ROCK) inhibitor partially rescued CKO enteroid development. Compared with littermate control mice, dextran sodium sulfate-treated βPix-deficient mice lost more weight and had greater impairment of intestinal barrier function, and more severe colonic mucosal injury. These findings reveal βPix expression is important for enterocyte development, intestinal homeostasis, and resistance to toxic injury.NEW & NOTEWORTHY To explore the role of βPix, a guanine nucleotide exchange factor encoded by ARHGEF7, in intestinal development and physiology, we created mice with intestinal epithelial cell Arhgef7/βPix deficiency. We found βPix essential for normal small intestinal epithelial cell proliferation, villus development, and mucosal resistance to injury. Moreover, Rho kinase signaling mediated developmental arrest observed in enteroids derived from βPix-deficient small intestinal crypts. Our studies provide insights into the role Arhgef7/βPix plays in intestinal epithelial homeostasis.

Patterns of genetic divergence and demographic history shed light on island-mainland population dynamics and melanic plumage evolution in the white-winged Fairywren

The existence of distinct traits in island versus mainland populations offers opportunities to gain insights into how eco-evolutionary processes operate under natural conditions. We used two island colonization events in the white-winged fairywren (Malurus leucopterus) to investigate the genomic and demographic origin of melanic plumage. This avian species is distributed across most of Australia, and males of the mainland subspecies (M. l. leuconotus) exhibit a blue nuptial plumage in contrast to males of two island subspecies - M. l. leucopterus on Dirk Hartog Island and M. l. edouardi on Barrow Island - that exhibit a black nuptial plumage. We used reduced-representation sequencing to explore differentiation and demographic history in this species and found clear patterns of divergence between mainland and island populations, with additional substructuring on the mainland. Divergence between the mainland and Dirk Hartog was approximately 10 times more recent than the split between the mainland and Barrow Island, supporting two independent colonizations. In both cases, estimated gene flow between the mainland and the islands was low, contributing to signals of divergence among subspecies. Our results present demographic reconstructions of mainland-island dynamics and associated plumage variation in white-winged fairywrens, with broader implications regarding our understanding of convergent evolution in insular populations.

Markers of epithelial-mesenchymal transition in an experimental breast cancer model induced by organophosphorous pesticides and estrogen

Breast cancer is a major health problem and accounted for 11.6% of all new cancer cases and 6.6% of all cancer deaths among women worldwide in 2018. However, its etiology has remained elusive. According to epidemiological studies, environmental factors are influencing the increase in the incidence of breast cancer risk. Components such as chemicals, including pesticides, are agents that produce deleterious effects on wildlife and humans. Among them, the organophosphorus pesticides, such as malathion, have largely been considered in this etiology. The epithelial-mesenchymal transition serves a key role in tumor progression and it is proposed that malathion is closely associated with the origin of this transition, among other causes. Moreover, proteins participating in this process are primordial in the transformation of a normal cell to a malignant tumor cell. The aim of the current study was to evaluate markers that indicated oncogenic properties. The results indicated greater expression levels of proteins associated with the epithelial-to-mesenchymal transition, including E-cadherin, Vimentin, Axl, and Slug in the rat mammary glands treated with malathion alone and combined with estrogen. Atropine was demonstrated to counteract the malathion effect as a muscarinic antagonist. The understanding of the use of markers in experimental models is crucial to identify different stages in the cancer process. The alteration of these markers may serve as a predicting factor that can be used to indicate whether a person has altered ducts or lobules in breast tissue within biopsies of individuals exposed to OPs or other environmental substances.

Epithelial-Mesenchymal Transition: Role in Cancer Progression and the Perspectives of Antitumor Treatment

About 90% of all malignant tumors are of epithelial nature. The epithelial tissue is characterized by a close interconnection between cells through cell-cell interactions, as well as a tight connection with the basement membrane, which is responsible for cell polarity. These interactions strictly determine the location of epithelial cells within the body and are seemingly in conflict with the metastatic potential that many cancers possess (the main criteria for highly malignant tumors). Tumor dissemination into vital organs is one of the primary causes of death in patients with cancer. Tumor dissemination is based on the so-called epithelial-mesenchymal transition (EMT), a process when epithelial cells are transformed into mesenchymal cells possessing high mobility and migration potential. More and more studies elucidating the role of the EMT in metastasis and other aspects of tumor progression are published each year, thus forming a promising field of cancer research. In this review, we examine the most recent data on the intracellular and extracellular molecular mechanisms that activate EMT and the role they play in various aspects of tumor progression, such as metastasis, apoptotic resistance, and immune evasion, aspects that have usually been attributed exclusively to cancer stem cells (CSCs). In conclusion, we provide a detailed review of the approved and promising drugs for cancer therapy that target the components of the EMT signaling pathways.

Rapamycin treatment correlates changes in primary cilia expression with cell cycle regulation in epithelial cells

Primary cilia are sensory organelles that regulate cell cycle and signaling pathways. In addition to its association with cancer, dysfunction of primary cilia is responsible for the pathogenesis of polycystic kidney disease (PKD) and other ciliopathies. Because the association between cilia formation or length and cell cycle or division is poorly understood, we here evaluated their correlation in this study. Using Spectral Karyotyping (SKY) technique, we showed that PKD and the cancer/tumorigenic epithelial cells PC3, DU145, and NL20-TA were associated with abnormal ploidy. We also showed that PKD and the cancer epithelia were highly proliferative. Importantly, the cancer epithelial cells had a reduction in the presence and/or length of primary cilia relative to the normal kidney (NK) cells. We then used rapamycin to restore the expression and length of primary cilia in these cells. Our subsequent analyses indicated that both the presence and length of primary cilia were inversely correlated with cell proliferation. Collectively, our data suggest that restoring the presence and/or length of primary cilia may serve as a novel approach to inhibit cancer cell proliferation.

Club Cell TRPV4 Serves as a Damage Sensor Driving Lung Allergic Inflammation

Airway epithelium is the first body surface to contact inhaled irritants and report danger. Here, we report how epithelial cells recognize and respond to aeroallergen alkaline protease 1 (Alp1) of Aspergillus sp., because proteases are critical components of many allergens that provoke asthma. In a murine model, Alp1 elicits helper T (Th) cell-dependent lung eosinophilia that is initiated by the rapid response of bronchiolar club cells to Alp1. Alp1 damages bronchiolar cell junctions, which triggers a calcium flux signaled through calcineurin within club cells of the bronchioles, inciting inflammation. In two human cohorts, we link fungal sensitization and/or asthma with SNP/protein expression of the mechanosensitive calcium channel, TRPV4. TRPV4 is also necessary and sufficient for club cells to sensitize mice to Alp1. Thus, club cells detect junction damage as mechanical stress, which signals danger via TRPV4, calcium, and calcineurin to initiate allergic sensitization.

Detecting heterogeneity in and between breast cancer cell lines

Background

Cellular heterogeneity in tumor cells is a well-established phenomenon. Genetic and phenotypic cell-to-cell variability have been observed in numerous studies both within the same type of cancer cells and across different types of cancers. Another known fact for metastatic tumor cells is that they tend to be softer than their normal or non-metastatic counterparts. However, the heterogeneity of mechanical properties in tumor cells are not widely studied.

Results

Here we analyzed single-cell optical stretcher data with machine learning algorithms on three different breast tumor cell lines and show that similar heterogeneity can also be seen in mechanical properties of cells both within and between breast tumor cell lines. We identified two clusters within MDA-MB-231 cells, with cells in one cluster being softer than in the other. In addition, we show that MDA-MB-231 cells and MDA-MB-436 cells which are both epithelial breast cancer cell lines with a mesenchymal-like phenotype derived from metastatic cancers are mechanically more different from each other than from non-malignant epithelial MCF-10A cells.

Conclusion

Since stiffness of tumor cells can be an indicator of metastatic potential, this result suggests that metastatic abilities could vary within the same monoclonal tumor cell line.

An RNAi screen unravels the complexities of Rho GTPase networks in skin morphogenesis

During mammalian embryogenesis, extensive cellular remodeling is needed for tissue morphogenesis. As effectors of cytoskeletal dynamics, Rho GTPases and their regulators are likely involved, but their daunting complexity has hindered progress in dissecting their functions. We overcome this hurdle by employing high throughput in utero RNAi-mediated screening to identify key Rho regulators of skin morphogenesis. Our screen unveiled hitherto unrecognized roles for Rho-mediated cytoskeletal remodeling events that impact hair follicle specification, differentiation, downgrowth and planar cell polarity. Coupling our top hit with gain/loss-of-function genetics, interactome proteomics and tissue imaging, we show that RHOU, an atypical Rho, governs the cytoskeletal-junction dynamics that establish columnar shape and planar cell polarity in epidermal progenitors. Conversely, RHOU downregulation is required to remodel to a conical cellular shape that enables hair bud invagination and downgrowth. Our findings underscore the power of coupling screens with proteomics to unravel the physiological significance of complex gene families.

Clathrin-Mediated Endocytosis Regulates a Balance between Opposing Signals to Maintain the Pluripotent State of Embryonic Stem Cells

Endocytosis is implicated in the maintenance of embryonic stem cell (ESC) pluripotency, although its exact role and the identity of molecular players remain poorly understood. Here, we show that the clathrin heavy chain (CLTC), involved in clathrin-mediated endocytosis (CME), is vital for maintaining mouse ESC (mESC) pluripotency. Knockdown of Cltc resulted in a loss of pluripotency accompanied by reduced E-cadherin (E-CAD) levels and increased levels of transforming growth factor β (TGF-β) and extracellular signal-regulated kinase (ERK) signaling. We demonstrate that both E-CAD and TGF-β receptor type 1 (TGF-βR1) are internalized through CME in mESCs. While E-CAD is recycled, TGF-βR1 is targeted for lysosomal degradation thus maintaining inverse levels of these molecules. Finally, we show that E-CAD interacts with ERK, and that the decreased pluripotency upon CME loss can be rescued by inhibiting TGF-βR, MEK, and GSK3β, or overexpressing E-CAD. Our results demonstrate that CME is critical for balancing signaling outputs to regulate ESC pluripotency, and possibly cell fate choices in early development.

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Knockdown of Cltc results in loss of mESC pluripotency

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CME regulates E-CAD and TGF-βR1 trafficking in mESCs

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ESCs lacking CME can be rescued by TGF-βR1/MEK inhibition or E-CAD overexpression

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CME balances opposing signaling outputs to maintain ESC pluripotency

CARCINOGENICITY OF MALATHION AND ESTROGEN IN AN EXPERIMENTAL RAT MAMMARY GLAND MODEL

Breast cancer is considered a major and common health problem in both developing and developed countries. The etiology of breast cancer, the most frequent malignancy diagnosed  in women in the western world, has remained unidentified. Chemicals as the  organophosphorous pesticide malathion have been used to control a wide range of sucking  and chewing pests of field crops, and are involved in the etiology of breast cancers. The  association between breast cancer initiation and prolonged exposure to estrogen suggests  that this hormone may also have an etiologic role in such a process. However, the key  factors behind the initiation of breast cancer remain to be elucidated. The effect of  environmental substances, such as malathion and estrogen was analyzed in an experimental rat mammary gland model. Different cytoplasmic proteins are key in the transformation of a  normal cell to a malignant tumor cell and among these are the Ras super family and Ras  homologous A (Rho-A). Both types of proteins were greater in animals treated with  malathion than those with estrogens. E-Cadherins constitute a large family of cell surface  proteins.

Resultsshowed greater expression of E-Cadherin and vimentin than c-Ha-ras and Rho-A in  rats treated by estrogens. In breast cancer, analysis using immunohistochemical markers is  an essential component of routine pathological examinations, and plays an important role in  the management of the disease by providing diagnostic and prognostic strategies.

The aimof the present study was to identify markers that can be used as a prognostic tool for breast cancer patients.

Direct Cell⁻Cell Interactions in the Endometrium and in Endometrial Pathophysiology

Cell contacts exhibit a considerable influence on tissue physiology and homeostasis by controlling paracellular and intercellular transport processes, as well as by affecting signaling pathways. Since they maintain cell polarity, they play an important role in cell plasticity. The knowledge about the junctional protein families and their interactions has increased considerably during recent years. In contrast to most other tissues, the endometrium undergoes extensive physiological changes and reveals an extraordinary plasticity due to its crucial role in the establishment and maintenance of pregnancy. These complex changes are accompanied by changes in direct cell–cell contacts to meet the various requirements in the respective developmental stage. Impairment of this sophisticated differentiation process may lead to failure of implantation and embryo development and may be involved in the pathogenesis of endometrial diseases. In this article, we focus on the knowledge about the distribution and regulation of the different junctional proteins in the endometrium during cycling and pregnancy, as well as in pathologic conditions such as endometriosis and cancer. Decoding these sophisticated interactions should improve our understanding of endometrial physiology as well as of the mechanisms involved in pathological conditions.

αE-Catenin Is a Positive Regulator of Pancreatic Islet Cell Lineage Differentiation

The development and function of epithelia depend on the establishment and maintenance of cell-cell adhesion and intercellular junctions, which operate as mechanosensor hubs for the transduction of biochemical signals regulating cell proliferation, differentiation, survival, and regeneration. Here, we show that αE-catenin, a key component of adherens junctions, functions as a positive regulator of pancreatic islet cell lineage differentiation by repressing the sonic hedgehog pathway (SHH). Thus, deletion of αE-catenin in multipotent pancreatic progenitors resulted in (1) loss of adherens junctions, (2) constitutive activation of SHH, (3) decrease in islet cell lineage differentiation, and (4) accumulation of immature Sox9⁺ progenitors. Pharmacological blockade of SHH signaling in pancreatic organ cultures and in vivo rescued this defect, allowing αE-catenin-null Sox9⁺ pancreatic progenitors to differentiate into endocrine cells. The results uncover crucial functions of αE-catenin in pancreatic islet development and harbor significant implications for the design of β cell replacement and regeneration therapies in diabetes.

Signaling pathways and mesenchymal transition in pediatric high-grade glioma

Pediatric high-grade gliomas (pHGG), including diffuse intrinsic pontine gliomas (DIPG), are the most lethal types of cancer in children. In recent years, it has become evident that these tumors are driven by epigenetic events, mainly mutations involving genes encoding Histone 3, setting them apart from their adult counterparts. These tumors are exceptionally resistant to chemotherapy and respond only temporarily to radiotherapy. Moreover, their delicate location and diffuse growth pattern make complete surgical resection impossible. In many other forms of cancer, chemo- and radioresistance, in combination with a diffuse, invasive phenotype, are associated with a transcriptional program termed the epithelial-to-mesenchymal transition (EMT). Activation of this program allows cancer cells to survive individually, invade surrounding tissues and metastasize. It also enables them to survive exposure to cytotoxic therapy, including chemotherapeutic drugs and radiation. We here suggest that EMT plays an important, yet poorly understood role in the biology and therapy resistance of pHGG and DIPG. This review summarizes the current knowledge on the major signal transduction pathways and transcription factors involved in the epithelial-to-mesenchymal transition in cancer in general and in pediatric HGG and DIPG in particular. Despite the fact that the mesenchymal transition has not yet been specifically studied in pHGG and DIPG, activation of pathways and high levels of transcription factors involved in EMT have been described. We conclude that the mesenchymal transition is likely to be an important element of the biology of pHGG and DIPG and warrants further investigation for the development of novel therapeutics.

Sphingolipid de novo biosynthesis is essential for intestine cell survival and barrier function

Serine palmitoyltransferase (SPT) is the rate-limiting enzyme for sphingolipid biosynthesis. SPT has two major subunits, SPTLC1 and SPTLC2. We previously found that liver Sptlc2 deficiency in early life impairs the development of adherens junctions. Here, we investigated the role of Sptlc2 deficiency in intestine. We treated Sptlc2-Flox/villin-Cre-ERT2 mice with tamoxifen (days 1, 2, and 3) to ablate Sptlc2 specifically in the intestine. At day 6 after tamoxifen treatment, Sptlc2-deficient mice had significantly decreased body weight with concurrent diarrhea and rectal bleeding. The number of goblet cells was reduced in both large and small intestine of Sptlc2-deficient mice compared with controls. Sptlc2 deficiency suppressed the level of mucin2 in the colon and increased circulating lipopolysaccharides, suggesting that SPT activity has a housekeeping function in the intestine. All Sptlc2-deficient mice died 7-10 days after tamoxifen treatment. Notably, supplementation with antibiotics and dexamethasone reduced lethality by 70%. We also found that colon specimens from patients with inflammatory bowel diseases had significantly reduced Sptlc2 expression, SPTLC2 staining, and goblet cell numbers. SPT activity is crucial for intestinal cell survival and barrier function.

Activation of KLF4 expression by small activating RNA promotes migration and invasion in colorectal epithelial cells

RNA activation mediated by small double-stranded RNAs targeting promoter sequence named small activating RNAs (saRNAs) is one of the mechanisms for gene activation. Artificial regulation of gene expression through RNA activation does not affect the alteration of the genomic DNA sequences or exogenous plasmid DNA, therefore it is a relative manageable approach for gene perturbation. KLF4 is a member of zinc-finger transcription factors and its functions in colorectal cells are still controversial. In order to elucidate the functions of KLF4, we synthesized saRNAs that target the promoter regions of KLF4 and transfected into varied colorectal epithelial cell lines. We found the KLF4 gene expression is specifically increased in the human normal epithelial cell NCM460 and colorectal epithelial cancer cell Caco-2 and HCT116, but not in other human colorectal epithelial cell lines. In addition, we observed that saRNAs induced overexpression of KLF4 could promote cell migration/invasion in NCM460 and HCT116 cell lines. This effect is mediated partly by inducing EMT and facilitating nuclear translocation of β-catenin.

Mitochondrial ribosomal protein S18-2 is highly expressed in endometrial cancers along with free E2F1

Endometrial cancer (EC) is one of the most frequent causes of cancer death among women in developed countries. Histopathological diagnosis and imaging techniques for EC are limited, thus new prognostic markers are needed to offer patients the best treatment and follow-up.In the present paper we showed that the level of mitochondrial ribosomal protein MRPS18-2 (S18-2) increased in EC compared with the normal endometrium and hyperplasia, based on a study of 42 patient biopsies. Importantly, high expression of free E2F1 in EC correlates well with high S18-2 expression. The EC cell line HEC-1-A, which overexpresses S18-2 constitutively, showed an increased proliferation capacity in vitro and in vivo (in SCID mice). Moreover, pan-keratin, beta-catenin and E-cadherin signals are diminished in these cells, compared to the parental HEC-1-A line, in contrast to vimentin signal that is increased. This may be associated with epithelial-mesenchymal cell transition (EMT).We conclude that high expression of S18-2 and free E2F1, and low pan-keratin, beta-catenin, and E-cadherin signals might be a good set of prognostic markers for EC.

An RNAi Screen Reveals an Essential Role for HIPK4 in Human Skin Epithelial Differentiation from iPSCs

Molecular mechanisms responsible for the development of human skin epithelial cells are incompletely understood. As a consequence, the efficiency to establish a pure skin epithelial cell population from human induced pluripotent stem cells (hiPSCs) remains poor. Using an approach including RNAi and high-throughput imaging of early epithelial cells, we identified candidate kinases involved in their differentiation from hiPSCs. Among these, we found HIPK4 to be an important inhibitor of this process. Indeed, its silencing increased the amount of generated skin epithelial precursors at an early time point, increased the amount of generated keratinocytes at a later time point, and improved growth and differentiation of organotypic cultures, allowing for the formation of a denser basal layer and stratification with the expression of several keratins. Our data bring substantial input regarding regulation of human skin epithelial differentiation and for improving differentiation protocols from pluripotent stem cells.

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High-throughput RNAi screen setup during human skin epithelial differentiation

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Identification of HIPK4 as a crucial blocker of human skin epithelial differentiation

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Improvement of human organotypic epithelial cultures after HIPK4 silencing

Gleaning Insights from Fecal Microbiota Transplantation and Probiotic Studies for the Rational Design of Combination Microbial Therapies

Beneficial microorganisms hold promise for the treatment of numerous gastrointestinal diseases. The transfer of whole microbiota via fecal transplantation has already been shown to ameliorate the severity of diseases such as Clostridium difficile infection, inflammatory bowel disease, and others. However, the exact mechanisms of fecal microbiota transplant efficacy and the particular strains conferring this benefit are still unclear. Rationally designed combinations of microbial preparations may enable more efficient and effective treatment approaches tailored to particular diseases. Here we use an infectious disease, C. difficile infection, and an inflammatory disorder, the inflammatory bowel disease ulcerative colitis, as examples to facilitate the discussion of how microbial therapy might be rationally designed for specific gastrointestinal diseases. Fecal microbiota transplantation has already shown some efficacy in the treatment of both these disorders; detailed comparisons of studies evaluating commensal and probiotic organisms in the context of these disparate gastrointestinal diseases may shed light on potential protective mechanisms and elucidate how future microbial therapies can be tailored to particular diseases.

Isolation and characterization of string-forming female germline stem cells from ovaries of neonatal mice

Germline stem cells are essential in the generation of both male and female gametes. In mammals, the male testis produces sperm throughout the entire lifetime, facilitated by testicular germline stem cells. Oocyte renewal ceases in postnatal or adult life in mammalian females, suggesting that germline stem cells are absent from the mammalian ovary. However, studies in mice, rats, and humans have recently provided evidence for ovarian female germline stem cells (FGSCs). A better understanding of the role of FGSCs in ovaries could help improve fertility treatments. Here, we developed a rapid and efficient method for isolating FGSCs from ovaries of neonatal mice. Notably, our FGSC isolation method could efficiently isolate on average 15 cell "strings" per ovary from mice at 1-3 days postpartum. FGSCs isolated from neonatal mice displayed the string-forming cell configuration at mitosis (i.e. a "stringing" FGSC (sFGSC) phenotype) and a disperse phenotype in postnatal mice. We also found that sFGSCs undergo vigorous mitosis especially at 1-3 days postpartum. After cell division, the sFGSC membranes tended to be connected to form sFGSCs. Moreover, F-actin filaments exhibited a cell-cortex distribution in sFGSCs, and E-cadherin converged in cell-cell connection regions, resulting in the string-forming morphology. Our new method provides a platform for isolating FGSCs from the neonatal ovary, and our findings indicate that FGCSs exhibit string-forming features in neonatal mice. The sFGSCs represent a valuable resource for analysis of ovary function and an in vitro model for future clinical use to address ovarian dysfunction.

E‑cadherin involvement in human lens epithelial cell transdifferentiation may be associated with N‑cadherin

E-cadherin, β-catenin and N‑cadherin serve key roles in the epithelial‑to‑mesenchymal transition (EMT) that leads to human lens epithelial cell (LEC) transdifferentiation and subsequent cataract formation. The present study aimed to investigate the role of E‑cadherin in LEC transdifferentiation. SRA01/04 human LECs were transfected with E‑cadherin short interfering (si)RNA (E‑cadherin siRNA group), negative control siRNA (NC group) or the transfection regent Lipofectamine 2000 (blank group). Reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR) was used to detect mRNA expression levels of E‑cadherin, N‑cadherin and β‑catenin, and western blot analysis was performed to measure the protein expression levels in the three groups. SRA01/04 cells transfected with E‑cadherin siRNA exhibited a significant decrease in the mRNA expression level of E‑cadherin (P<0.05) and N‑cadherin (P<0.05), whereas no significant changes were identified for β‑catenin expression (P>0.05). Consistent with the results of RT‑qPCR, western blotting demonstrated that the protein expression levels of E‑cadherin and N‑cadherin were notably decreased in E‑cadherin siRNA‑transfected cells, whereas the protein expression level of β‑catenin remained unchanged. Results from the present study indicated that E‑cadherin may be involved in human LEC transdifferentiation by affecting N‑cadherin expression.

Mechanisms of collective cell movement lacking a leading or free front edge in vivo

Collective cell movement is one of the strategies for achieving the complex shapes of tissues and organs. In this process, multiple cells within a group held together by cell-cell adhesion acquire mobility and move together in the same direction. In some well-studied models of collective cell movement, the mobility depends strongly on traction generated at the leading edge by cells located at the front. However, recent advances in live-imaging techniques have led to the discovery of other types of collective cell movement lacking a leading edge or even a free edge at the front, in a diverse array of morphological events, including tubule elongation, epithelial sheet extension, and tissue rotation. We herein review some of the developmental events that are organized by collective cell movement and attempt to elucidate the underlying cellular and molecular mechanisms, which include membrane protrusions, guidance cues, cell intercalation, and planer cell polarity, or chirality pathways.

miR-223 promotes colon cancer by directly targeting p120 catenin

microRNA (miRNA) dysregulation is frequently observed in colon cancer. Previous studies found that miR-223 is upregulated in colon cancer and functions as an oncogene. Conversely, p120 is often downregulated or even absent in colon cancer, and is a likely tumor suppressor. The present study showed that increased miR-223 and decreased p120 levels are associated with colon cancer malignancy, and p120 expression is negatively correlated with miR-223 expression. A dual luciferase reporter assay showed that miR-223 directly targets p120. miR-223 upregulation in a colon cancer cell line upregulated c-Myc, cyclinD1, MMP7, and vimentin expression, downregulated E-cadherin, increased nuclear expression of β-catenin, and enhanced RhoA activation. We suggest miR-223 may promote colon cancer cell invasion and metastasis by downregulating p120, thereby reducing intercellular adhesion, promoting RhoA activity, and activating β-catenin signaling. Thus miR-223 functions as an oncogene in colon cancer and may be a potential diagnostic and therapeutic target for anti-colon cancer treatment.

Molecular and cytoskeletal regulations in epidermal development

At the surface of the body, the epidermis covers great depth in its developmental regulation. While many genes have been shown to be important for skin development through their associations with disease phenotypes in mice and human, it is in the past decade that the intricate interplay between various molecules become gradually revealed through sophisticated genetic models and imaging analyses. In particular, there is increasing evidence suggesting that cytoskeleton-associated proteins, including adhesion proteins and the crosslinker proteins may play critical roles in regulating epidermis development. We here provide a broad overview of the various molecules involved in epidermal development with special emphasis on the cytoskeletal components.

Novel peptides for deciphering structural and signalling functions of E-cadherin in mouse embryonic stem cells

We have previously shown that E-cadherin regulates the naive pluripotent state of mouse embryonic stem cells (mESCs) by enabling LIF-dependent STAT3 phosphorylation, with E-cadherin null mESCs exhibiting over 3000 gene transcript alterations and a switch to Activin/Nodal-dependent pluripotency. However, elucidation of the exact mechanisms associated with E-cadherin function in mESCs is compounded by the difficulty in delineating the structural and signalling functions of this protein. Here we show that mESCs treated with the E-cadherin neutralising antibody DECMA-1 or the E-cadherin binding peptide H-SWELYYPLRANL-NH2 (Epep) exhibit discrete profiles for pluripotent transcripts and NANOG protein expression, demonstrating that the type of E-cadherin inhibitor employed dictates the cellular phenotype of mESCs. Alanine scanning mutation of Epep revealed residues critical for Tbx3, Klf4 and Esrrb transcript repression, cell-cell contact abrogation, cell survival in suspension, STAT3 phosphorylation and water solubility. STAT3 phosphorylation was found to be independent of loss of cell-cell contact and Activin/Nodal-dependent pluripotency and a peptide is described that enhances STAT3 phosphorylation and Nanog transcript and protein expression in mESCs. These peptides represent a useful resource for deciphering the structural and signalling functions of E-cadherin and demonstrate that complete absence of E-cadherin protein is likely required for hierarchical signalling pathway alterations in mESCs.

Liver serine palmitoyltransferase activity deficiency in early life impairs adherens junctions and promotes tumorigenesis

Serine palmitoyltransferase is the key enzyme in sphingolipid biosynthesis. Mice lacking serine palmitoyltransferase are embryonic lethal. We prepared liver-specific mice deficient in the serine palmitoyltransferase long chain base subunit 2 gene using an albumin-cyclization recombination approach and found that the deficient mice have severe jaundice. Moreover, the deficiency impairs hepatocyte polarity, attenuates liver regeneration after hepatectomy, and promotes tumorigenesis. Importantly, we show that the deficiency significantly reduces sphingomyelin but not other sphingolipids in hepatocyte plasma membrane; greatly reduces cadherin, the major protein in adherens junctions, on the membrane; and greatly induces cadherin phosphorylation, an indication of its degradation. The deficiency affects cellular distribution of β-catenin, the central component of the canonical Wnt pathway. Furthermore, such a defect can be partially corrected by sphingomyelin supplementation in vivo and in vitro.

CONCLUSION

The plasma membrane sphingomyelin level is one of the key factors in regulating hepatocyte polarity and tumorigenesis. (Hepatology 2016;64:2089-2102).

α3 Integrin of Cell-Cell Contact Mediates Kidney Fibrosis by Integrin-Linked Kinase in Proximal Tubular E-Cadherin Deficient Mice

Loss of E-cadherin marks a defect in epithelial integrity and polarity during tissue injury and fibrosis. Whether loss of E-cadherin plays a causal role in fibrosis is uncertain. α3β1 Integrin has been identified to complex with E-cadherin in cell-cell adhesion, but little is known about the details of their cross talk. Herein, E-cadherin gene (Cdh1) was selectively deleted from proximal tubules of murine kidney by Sglt2Cre. Ablation of E-cadherin up-regulated α3β1 integrin at cell-cell adhesion. E-cadherin-deficient proximal tubular epithelial cell displayed enhanced transforming growth factor-β1-induced α-smooth muscle actin (α-SMA) and vimentin expression, which was suppressed by siRNA silencing of α3 integrin, but not β1 integrin. Up-regulation of transforming growth factor-β1-induced α-SMA was mediated by an α3 integrin-dependent increase in integrin-linked kinase (ILK). Src phosphorylation of β-catenin and consequent p-β-catenin-Y654/p-Smad2 transcriptional complex underlies the transcriptional up-regulation of ILK. Kidney fibrosis after unilateral ureteric obstruction or ischemia reperfusion was increased in proximal tubule E-cadherin-deficient mice in comparison to that of E-cadherin intact control mice. The exacerbation of fibrosis was explained by the α3 integrin-dependent increase of ILK, β-catenin nuclear translocation, and α-SMA/proximal tubular-specific Cre double positive staining in proximal tubular epithelial cell. These studies delineate a nonconventional integrin/ILK signaling by α3 integrin-dependent Src/p-β-catenin-Y654/p-Smad2-mediated up-regulation of ILK through which loss of E-cadherin leads to kidney fibrosis.

Transient Expression of WNT2 Promotes Somatic Cell Reprogramming by Inducing β-Catenin Nuclear Accumulation

Treatment with several Wnt/β-catenin signaling pathway regulators can change the cellular reprogramming efficiency; however, the dynamics and role of endogenous Wnt/β-catenin signaling in reprogramming remain largely unanswered. Here we identify the upregulation of WNT2 and subsequent β-catenin nuclear accumulation as key events in reprogramming. Transient nuclear accumulation of β-catenin occurs early in MEF reprogramming. Wnt2 is strongly expressed in the early stage of reprogramming. Wnt2 knockdown suppresses the nuclear accumulation of β-catenin and reduces the reprogramming efficiency. WNT2 overexpression promotes β-catenin nuclear accumulation and enhances the reprogramming efficiency. WNT2 contributes to the promotion of cell proliferation. Experiments with several drugs that control the Wnt pathway also indicate the importance of β-catenin nuclear accumulation in reprogramming. Our findings reveal the role of WNT2/β-catenin signaling in reprogramming.

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Nuclear accumulation of β-catenin occurs in the early stage of MEF reprogramming

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Wnt2 expression is transiently increased during MEF reprogramming

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WNT2 promotes both the β-catenin nuclear accumulation and the reprogramming process

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Nuclear accumulation of β-catenin is important for MEF reprogramming

The splice variant Ehm2/1 in breast cancer MCF-7 cells interacted with β-catenin and increased its localization to plasma membrane

Ehm2, which belongs to the FERM superfamily, is a metastasis-associated protein.