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Catenin
Terms modified by Catenin Selected AbstractsHuman colon cancer epithelial cells harbour active HEDGEHOG-GLI signalling that is essential for tumour growth, recurrence, metastasis and stem cell survival and expansionEMBO MOLECULAR MEDICINE, Issue 6-7 2009Frédéric Varnat Abstract Human colon cancers often start as benign adenomas through loss of APC, leading to enhanced ,CATENIN (,CAT)/TCF function. These early lesions are efficiently managed but often progress to invasive carcinomas and incurable metastases through additional changes, the nature of which is unclear. We find that epithelial cells of human colon carcinomas (CCs) and their stem cells of all stages harbour an active HH-GLI pathway. Unexpectedly, they acquire a high HEDGEHOG-GLI (HH-GLI) signature coincident with the development of metastases. We show that the growth of CC xenografts, their recurrence and metastases require HH-GLI function, which induces a robust epithelial-to-mesenchymal transition (EMT). Moreover, using a novel tumour cell competition assay we show that the self-renewal of CC stem cells in vivo relies on HH-GLI activity. Our results indicate a key and essential role of the HH-GLI1 pathway in promoting CC growth, stem cell self-renewal and metastatic behavior in advanced cancers. Targeting HH-GLI1, directly or indirectly, is thus predicted to decrease tumour bulk and eradicate CC stem cells and metastases. [source] Novel brain 14-3-3 interacting proteins involved in neurodegenerative diseaseFEBS JOURNAL, Issue 16 2005Shaun Mackie We isolated two novel 14-3-3 binding proteins using 14-3-3 , as bait in a yeast two-hybrid screen of a human brain cDNA library. One of these encoded the C-terminus of a neural specific armadillo-repeat protein, ,-catenin (neural plakophilin-related arm-repeat protein or neurojungin). ,-Catenin from brain lysates was retained on a 14-3-3 affinity column. Mutation of serine 1072 in the human protein and serine 1094 in the equivalent site in the mouse homologue (in a consensus binding motif for 14-3-3) abolished 14-3-3 binding to ,-catenin in vitro and in transfected cells. ,-catenin binds to presenilin-1, encoded by the gene most commonly mutated in familial Alzheimer's disease. The other clone was identified as the insulin receptor tyrosine kinase substrate protein of 53 kDa (IRSp53). Human IRSp53 interacts with the gene product implicated in dentatorubral-pallidoluysian atrophy, an autosomal recessive disorder associated with glutamine repeat expansion of atrophin-1. [source] Abnormal lens morphogenesis and ectopic lens formation in the absence of ,-catenin function,GENESIS: THE JOURNAL OF GENETICS AND DEVELOPMENT, Issue 4 2007Jana Kreslova Abstract ,-Catenin plays a key role in cadherin-mediated cell adhesion as well as in canonical Wnt signaling. To study the role of ,-catenin during eye development, we used conditional Cre/loxP system in mouse to inactivate ,-catenin in developing lens and retina. Inactivation of ,-catenin does not suppress lens fate, but instead results in abnormal morphogenesis of the lens. Using BAT-gal reporter mice, we show that ,-catenin-mediated Wnt signaling is notably absent from lens and neuroretina throughout eye development. The observed defect is therefore likely due to the cytoskeletal role of ,-catenin, and is accompanied by impaired epithelial cell adhesion. In contrast, inactivation of ,-catenin in the nasal ectoderm, an area with active Wnt signaling, results in formation of crystallin-positive ectopic lentoid bodies. These data suggest that, outside of the normal lens, ,-catenin functions as a coactivator of canonical Wnt signaling to suppress lens fate. genesis 45:157,168, 2007. Published 2007 Wiley-Liss, Inc. [source] Cytoplasmic ,-catenin accumulation is a good prognostic marker in upper and lower gastrointestinal adenocarcinomasHISTOPATHOLOGY, Issue 1 2010Michael G A Norwood Norwood M G A, Bailey N, Nanji M, Gillies R S, Nicholson A, Ubhi S, Darnton J J, Steyn R S, Womack C, Hughes A, Hemingway D, Harrison R, Waters R & Jankowski J A (2010) Histopathology,57, 101,111 Cytoplasmic ,-catenin accumulation is a good prognostic marker in upper and lower gastrointestinal adenocarcinomas Aims:, ,-Catenin is an important molecule in cancer biology. Membranous ,-catenin enhances cellular differentiation and inhibits invasion by its action on E-cadherin. The aim was to ascertain whether the cellular expression of these molecules in colorectal and oesophageal cancer specimens is associated with survival in patients with gastrointestinal cancer. Methods and results:, Tumour samples from 149 patients undergoing resection for colorectal adenocarcinoma and 147 patients undergoing resection for oesophageal adenocarcinoma were retrospectively analysed using immunohistochemical techniques to assess ,-catenin expression. Increasing ,-catenin expression in the cytoplasm was associated with improved survival for colorectal cancer cases on both univariate (P = 0.003) and multivariate (P = 0.01) analysis. In addition, increased expression in the most recent cohort of oesophageal adenocarcinoma patients was associated with improved TNM staging (P = 0.007). Membrane expression was weakly associated with survival in colorectal cancer on univariate analysis (P = 0.09), but not on multivariate analysis (P = 0.21). Complete absence of ,-catenin expression at all three sites was associated with reduced 5-year survival in colorectal cancer. Conclusions:, This is one of the largest prognostic studies of ,-catenin in gastrointestinal adenocarcinoma. It shows that low levels of cytoplasmic ,-catenin expression are associated with reduced survival in patients with colorectal cancer as well as worse TNM staging in oesophageal adenocarcinoma (a recognized surrogate end-point for survival). We believe this is the first time that this has been reported. This finding should be tested prospectively in oncological trials to validate whether the presence of cytoplasmic ,-catenin could be used as a prognostic marker for less aggressive disease. [source] Overexpression of Smurf2 Stimulates Endochondral Ossification Through Upregulation of ,-Catenin,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 4 2008Qiuqian Wu MD Abstract Ectopic expression of Smurf2 in chondrocytes and perichondrial cells accelerated endochondral ossification by stimulating chondrocyte maturation and osteoblast development through upregulation of ,-catenin in Col2a1-Smurf2 embryos. The mechanism underlying Smurf2-mediated morphological changes during embryonic development may provide new mechanistic insights and potential targets for prevention and treatment of human osteoarthritis. Introduction: Our recent finding that adult Col2a1-Smurf2 mice have an osteoarthritis-like phenotype in knee joints prompted us to examine the role of Smurf2 in the regulation of chondrocyte maturation and osteoblast differentiation during embryonic endochondral ossification. Materials and Methods: We analyzed gene expression and morphological changes in developing limbs by immunofluorescence, immunohistochemistry, Western blot, skeletal preparation, and histology. A series of markers for chondrocyte maturation and osteoblast differentiation in developing limbs were examined by in situ hybridization. Results: Ectopic overexpression of Smurf2 driven by the Col2a1 promoter was detected in chondrocytes and in the perichondrium/periosteum of 16.5 dpc transgenic limbs. Ectopic Smurf2 expression in cells of the chondrogenic lineage inhibited chondrocyte differentiation and stimulated maturation; ectopic Smurf2 in cells of the osteoblastic lineage stimulated osteoblast differentiation. Mechanistically, this could be caused by a dramatic increase in the expression of ,-catenin protein levels in the chondrocytes and perichondrial/periosteal cells of the Col2a1-Smurf2 limbs. Conclusions: Ectopic expression of Smurf2 driven by the Col2a1 promoter accelerated the process of endochondral ossification including chondrocyte maturation and osteoblast differentiation through upregulation of ,-catenin, suggesting a possible mechanism for development of osteoarthritis seen in these mice. [source] ,-Catenin signaling in biological control and cancerJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 4 2007Nancy Gavert Abstract A coordinated integration of cell,cell adhesion and the control of gene expression is essential for the development of multicellular, differentiated organisms. ,-Catenin fulfils important regulatory functions in both cell,cell adhesion by linking cadherin adhesion receptors to the cytoskeleton, and also as a key element in the Wnt signaling pathway where it acts as cotranscriptional activator of target genes in the cell nucleus. Wnt signaling is involved in numerous aspects of embryonic development and in the control of tissue self-renewal in a variety of adult tissues. Hyperactivation of Wnt signaling, mostly by affecting ,-catenin functions, is a hallmark of colon cancer and of many other human cancers. In this prospect, we discuss studies pointing to the molecular mechanisms that govern the integration between cell,cell adhesion and gene expression, as reflected in the switches between these two functions of ,-catenin in colon cancer cells. J. Cell. Biochem. 102: 820,828, 2007. © 2007 Wiley-Liss, Inc. [source] ,-Catenin expression in human neural cell lines following exposure to cytokines and growth factorsNEUROPATHOLOGY, Issue 2 2000Jun-ichi Satoh ,-Catenin acts as a key mediator of the Wnt/Wingless signaling pathway involved in cell proliferation, differentiation and survival. Recent studies have shown that an unstable interaction between ,-catenin and the mutant presenilin-1 induces neuronal apoptosis, and that ,-catenin levels are decreased in the brains of patients with Alzheimer's disease (AD). Since activated microglia and astrocytes play a role in the process of neuronal degeneration in AD, the cytokine/growth factor-regulated expression of ,-catenin in human neural cell lines, including NTera2 teratocarcinoma-derived differentiated neurons (NTera2-N), IMR-32 neuroblastoma, SKN-SH neuroblastoma and U-373MG astrocytoma, was studied quantitatively following exposure to epidermal growth factor (EGF), basic fibroblast growth factor (bFGF), brain-derived neurotrophic factor (BDNF), tumor necrosis factor-, (TNF-,), interleukin (IL)-1,, IL-6, interferon (IFN)-,, transforming growth factor (TGF)-,1, dibutyryl cyclic adenosine 3,,5,-cyclic monophosphate (cAMP) (dbcAMP) or phorbol 12-myristate 13-acetate (PMA). ,-Catenin mRNA expressed constitutively in all of these cell lines was unaffected by treatment with any factors examined. In contrast, ,-catenin protein levels were reduced markedly in NTera2-N cells by exposure to dbcAMP, EGF or bFGF, and in U-373MG cells by treatment with dbcAMP or PMA, but were unaffected in any cell lines by BDNF, TNF-,, IL-1,, IL-6, IFN-, or TGF-,1. These results indicate that ,-catenin is expressed constitutively in human neural cells and downregulated at a protein level by a set of growth factors in a cell type-specific manner. [source] Immunohistochemical comparison of ,-catenin expression by human normal epidermis and epidermal tumorsTHE JOURNAL OF DERMATOLOGY, Issue 11 2007Keiko FUKUMARU ABSTRACT ,-Catenin, a cytoplasmic protein that binds directly to the intracellular domain of cadherin, controls various functions such as cell adhesion. In many human carcinomas, E-cadherin-mediated cell,cell adhesion is lost or disturbed and related to metastasis. The purpose of this study was to compare the expression of ,-catenin in the normal epidermal keratinocytes and samples from cutaneous benign and malignant epidermal tumors in 140 patients. Our study population consisted of 140 patients with benign or malignant epidermal tumors. Using immunohistochemical methods, we compared the expression of ,-catenin in their normal epidermal keratinocytes, and in samples from 61 benign (seborrheic keratosis, n = 33; verruca vulgaris, n = 14; keratoacanthoma, n = 14), and 79 malignant (Bowen's disease, n = 18; basal cell carcinoma, n = 33; squamous cell carcinoma, n = 28) epidermal tumors. ,-Catenin was found to be expressed in the cell membrane of normal keratinocytes. Compared to other cell components of the normal epidermis, basal cells showed the strongest ,-catenin expression in all 140 patients. While absent in three of 61 benign tumors, compared to normal basal cells, the expression of ,-catenin in the other 58 tumors was not significantly different; it was reduced in 71 of 79 malignant tumors (P < 0.0001). In Bowen's disease, the expression of ,-catenin on the tumor cell membrane was reduced, however, strong expression was seen in the nuclei and cytoplasm. Our results suggest that ,-catenin expression on the membrane of keratinocytes is associated with the differentiation of normal keratinocytes but not with their stage of differentiation, nor with the proliferation ability of epidermal tumor cells. [source] ,-Catenin dysregulation in cancer: interactions with E-cadherin and beyond,THE JOURNAL OF PATHOLOGY, Issue 2 2010Qun Lu Abstract Stable E-cadherin-based adherens junctions are pivotal in maintaining epithelial tissue integrity and are the major barrier for epithelial cancer metastasis. Proteins of the p120ctn subfamily have emerged recently as critical players for supporting this stability. The identification of the unique juxtamembrane domain (JMD) in E-cadherin that binds directly to ,-catenin/NPRAP/neurojungin (CTNND2) and p120ctn (CTNND1) provides a common motif for their interactions. Recently, crystallographic resolution of the JMD of p120ctn further highlighted possibilities of intervening between interactions of p120ctn subfamily proteins and E-cadherin for designing anti-cancer therapeutics. For most epithelial cancers, studies have demonstrated a reduction of p120ctn expression or alteration of its subcellular distribution. On the other hand, ,-catenin, a primarily neural-enriched protein in the brain of healthy individuals, is up-regulated in all cancer types that have been studied to date. Two research articles in the September 2010 issue of The Journal of Pathology increase our understanding of the involvement of these proteins in lung cancer. One reports the identification of rare p120ctn (CTNND1) gene amplification in lung cancer. One mechanism by which ,-catenin and p120ctn may play a role in carcinogenesis is their competitive binding to E-cadherin through the JMD. The other presents the first vigorous characterization of ,-catenin overexpression in lung cancer. Unexpectedly, the authors observed that ,-catenin promotes malignant phenotypes of non-small cell lung cancer by non-competitive binding to E-cadherin with p120ctn in the cytoplasm. Looking towards the future, the understanding of ,-catenin and p120ctn with and beyond their localization at the cell,cell junction should provide further insight into their roles in cancer pathogenesis. Copyright © 2010 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd. Invited Commentary for Castillo et al. Gene amplification of the transcription factor DP1 and CTNND1 in human lung cancer, Journal of Pathology, 2010; 222: 89,98. And for Zhang et al. ,-Catenin promotes malignant phenotype of non-small cell lung cancer by non-competative binding to E-cadherin with p120ctn in cytoplasm. Journal of Pathology, 2010; 222: 76,88. [source] Transcriptional activation of the ,- catenin gene at the invasion front of colorectal liver metastases,THE JOURNAL OF PATHOLOGY, Issue 3 2009Obul R Bandapalli Abstract ,-Catenin is a pivotal molecule of the Wnt-signalling pathway, involved in regulation of developmental and oncogenic processes as well as in intercellular adhesion. So far, ,-catenin has been thought to be regulated mainly at the protein level. Here, we provide evidence for a transcriptional mechanism of ,-catenin regulation at the invasion front of colorectal liver metastases. In a nude mouse/LS174T cell xenograft model of colorectal liver metastases, we observed ,-catenin up-regulation at the mRNA and protein levels and a 13.7-fold increase of ,-catenin promoter activity in the cancer cells of the invasion front. In addition, the promoter activity was five-fold higher in the interior of the tumour than in cells growing in cell culture. In vitro studies revealed binding of TCF-4 to the ,-catenin promoter and reduced promoter activity by over-expression of dominant negative TCF-4, or ,-catenin knock-down and increased activity by ,-catenin over-expression, indicating that ,-catenin acts as co-transcription factor of its own promoter. In 55% (7/13) of clinical specimens, ,-catenin mRNA was markedly elevated in the cancer cells of the invasion front. Elevation of mRNA was paralleled by increased nuclear and cytoplasmic ,-catenin protein concentrations. These data indicate that transcriptional regulation contributes to the dynamic changes of ,-catenin levels upon the confrontation of tumour cells with the host microenvironment. Copyright © 2008 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd. [source] Alterations of M-cadherin, neural cell adhesion molecule and , -catenin expression in satellite cells during overload-induced skeletal muscle hypertrophyACTA PHYSIOLOGICA, Issue 3 2006M. Ishido Abstract Aim:, Neural cell adhesion molecule (NCAM) and M-cadherin are cell adhesion molecules expressed on the surface of skeletal muscle satellite cell (SC). During myogenic morphogenesis, M-cadherin participates in mediating terminal differentiation and fusion of myoblasts by forming a complex with , -catenin and that NCAM contributes to myotube formation by fusion of myoblasts. Hypertrophy and hyperplasia of functionally overloaded skeletal muscle results from the fusion with SCs into the existing myofibres or new myofibre formation by SC,SC fusion. However, the alterations of NCAM, M-cadherin and , -catenin expressions in SCs in response to functional overload have not been investigated. Methods:, Using immunohistochemical approaches, we examined the temporal and spatial expression patterns of these factors expressed in SCs during the functional overload of skeletal muscles. Results:, Myofibres with SCs showing NCAM+/M-cadherin,, NCAM+/M-cadherin+ or NCAM,/M-cadherin+ were detected in overloaded muscles. The percentage changes of myofibres with SCs showing NCAM+/M-cadherin,, NCAM+/M-cadherin+ or NCAM,/M-cadherin+ were elevated in day-3 post-overloaded muscles, and then only the percentage changes of myofibres with SCs showing NCAM,/M-cadherin+ were significantly increased in day-7 post-overload muscles (P < 0.05). Both , -catenin and M-cadherin were co-localized throughout quiescent, proliferation and differentiation stages of SCs. Conclusion:, These results suggested that the expressions of NCAM, M-cadherin and , -catenin in SCs may be controlled by distinct regulatory mechanisms during functional overload, and that interactions among NCAM, M-cadherin and , -catenin in SCs may play important roles to contribute to overload-induced muscle hypertrophy via fusion with each other or into the existing myofibres of SCs. [source] Actin filament binding by a monomeric IQGAP1 fragment with a single calponin homology domainCYTOSKELETON, Issue 4 2004Scott C. Mateer Abstract IQGAP1 is a homodimeric protein that reversibly associates with F-actin, calmodulin, activated Cdc42 and Rac1, CLIP-170, ,-catenin, and E-cadherin. Its F-actin binding site includes a calponin homology domain (CHD) located near the N-terminal of each subunit. Prior studies have implied that medium- to high-affinity F-actin binding (5,50 ,M Kd) requires multiple CHDs located either on an individual polypeptide or on distinct subunits of a multimeric protein. For IQGAP1, a series of six tandem IQGAP coiled-coil repeats (IRs) located past the C-terminal of the CHD of each subunit support protein dimerization and, by extension, the IRs or an undefined subset of them were thought to be essential for F-actin binding mediated by its CHDs. Here we describe efforts to determine the minimal region of IQGAP1 capable of binding F-actin. Several truncation mutants of IQGAP1, which contain progressive deletions of the IRs and CHD, were assayed for F-actin binding in vitro. Fragments that contain both the CHD and at least one IR could bind F-actin and, as expected, removal of all six IRs and the CHD abolished binding. Unexpectedly, a fragment called IQGAP12-210, which contains the CHD, but lacks IRs, could bind actin filaments. IQGAP12-210 was found to be monomeric, to bind F-actin with a Kd of ,47 ,M, to saturate F-actin at a molar ratio of one IQGAP12-210 per actin monomer, and to co-localize with cortical actin filaments when expressed by transfection in cultured cells. These collective results identify the first known example of high-affinity actin filament binding mediated by a single CHD. Cell Motil. Cytoskeleton 58:231,241, 2004. © 2004 Wiley-Liss, Inc. [source] Novel genes involved in canonical Wnt/, -catenin signaling pathway in early Ciona intestinalis embryosDEVELOPMENT GROWTH & DIFFERENTIATION, Issue 4 2008Shuichi Wada We report here characterization of five genes for novel components of the canonical Wnt/, -catenin signaling pathway. These genes were identified in the ascidian Ciona intestinalis through a loss-of-function screening for genes required for embryogenesis with morpholinos, and four of them have counterparts in vertebrates. The five genes we studied are as follows: Ci-PGAP1, a Ciona orthologue of human PGAP1, which encodes GPI (glycosylphosphatidylinositol) inositol-deacylase, Ci-ZF278, a gene encoding a C2H2 zinc-finger protein, Ci-C10orf11, a Ciona orthologue of human C10orf11 that encodes a protein with leucine-rich repeats, Ci-Spatial/C4orf17, a single counterpart for two human genes Spatial and C4orf17, and Ci-FLJ10634, a Ciona orthologue of human FLJ10634 that encodes a member of the J-protein family. Knockdown of each of the genes mimicked , -catenin knockdown and resulted in suppression of the expression of , -catenin downstream genes (Ci-FoxD, Ci-Lhx3, Ci-Otx and Ci-Fgf9/16/20) and subsequent endoderm formation. For every gene, defects in knockdown embryos were rescued by overexpression of a constitutively active form, but not wild-type, of Ci- , -catenin. Dosage-sensitive interactions were found between Ci-,-catenin and each of the genes. These results suggest that these five genes act upstream of or parallel to Ci- , -catenin in the Wnt/, -catenin signaling pathway in early Ciona embryos. [source] Initiation of limb regeneration: The critical steps for regenerative capacityDEVELOPMENT GROWTH & DIFFERENTIATION, Issue 1 2008Hitoshi Yokoyama While urodele amphibians (newts and salamanders) can regenerate limbs as adults, other tetrapods (reptiles, birds and mammals) cannot and just undergo wound healing. In adult mammals such as mice and humans, the wound heals and a scar is formed after injury, while wound healing is completed without scarring in an embryonic mouse. Completion of regeneration and wound healing takes a long time in regenerative and non-regenerative limbs, respectively. However, it is the early steps that are critical for determining the extent of regenerative response after limb amputation, ranging from wound healing with scar formation, scar-free wound healing, hypomorphic limb regeneration to complete limb regeneration. In addition to the accumulation of information on gene expression during limb regeneration, functional analysis of signaling molecules has recently shown important roles of fibroblast growth factor (FGF), Wnt/,-catenin and bone morphogenic protein (BMP)/Msx signaling. Here, the routine steps of wound healing/limb regeneration and signaling molecules specifically involved in limb regeneration are summarized. Regeneration of embryonic mouse digit tips and anuran amphibian (Xenopus) limbs shows intermediate regenerative responses between the two extremes, those of adult mammals (least regenerative) and urodele amphibians (more regenerative), providing a range of models to study the various abilities of limbs to regenerate. [source] Atypical molecular profile for joint development in the avian costal jointDEVELOPMENTAL DYNAMICS, Issue 10 2010B.B. Winslow Abstract Development of synovial joints involves generation of cartilaginous anlagen, formation of interzones between cartilage anlagen, and cavitation of interzones to produce fluid filled cavities. Interzone development is not fully understood, but interzones are thought to develop from skeletogenic cells that are inhibited from further chondrogenic development by a cascade of gene expression including Wnt and Bmp family members. We examined the development of the rarely studied avian costal joint to better understand mechanisms of joint development. The costal joint is found within ribs, is morphologically similar to the metatarsophalangeal joint, and undergoes cavitation in a similar manner. In contrast to other interzones, Wnt14/9a, Gdf5, Chordin, Barx1, and Bapx1 are absent from the costal joint interzone, consistent with the absence of active ,-catenin and phosphorylated Smad 1/5/8. However Autotaxin and Noggin are expressed. The molecular profile of the costal joint suggests there are alternative mechanisms of interzone development. Developmental Dynamics 239:2547,2557, 2010. © 2010 Wiley-Liss, Inc. [source] Tankyrase is necessary for canonical Wnt signaling during kidney developmentDEVELOPMENTAL DYNAMICS, Issue 7 2010Courtney M. Karner Abstract Recent studies using small molecule antagonists have revealed that the poly(ADP-ribose) polymerases (PARPs) Tankyrase 1 and 2 are critical regulators of canonical Wnt signaling in some cellular contexts. However, the absence of any activity during zebrafish embryogenesis suggested that the tankyrases may not be general/core components of the Wnt pathway. Here, we show that Tnks1 and 2 are broadly expressed during mouse development and are essential during kidney and lung development. In the kidney, blockage of tankyrase activity phenocopies the effect of blocking production of all Wnt ligands. Tankyrase inhibition can be rescued by activation of ,-catenin demonstrating its specificity for the Wnt pathway. In addition, treatment with tankyrase inhibitors appears to be completely reversible in some cell types. These studies suggest that the tankyrases are core components of the canonical Wnt pathway and their inhibitors should enjoy broad usage as antagonists of Wnt signaling. Developmental Dynamics 239:2014,2023, 2010 © 2010 Wiley-Liss, Inc. [source] Regulation of Wnt/,-catenin signaling by protein kinasesDEVELOPMENTAL DYNAMICS, Issue 1 2010Esther M. Verheyen Abstract The Wnt/,-catenin signaling pathway plays essential roles during development and adult tissue homeostasis. Inappropriate activation of the pathway can result in a variety of malignancies. Protein kinases have emerged as key regulators at multiple steps of the Wnt pathway. In this review, we present a synthesis covering the latest information on how Wnt signaling is regulated by diverse protein kinases. Developmental Dynamics 239:34,44, 2010. © 2009 Wiley-Liss, Inc. [source] Organ patterning in the adult stage: The role of Wnt/,-catenin signaling in liver zonation and beyondDEVELOPMENTAL DYNAMICS, Issue 1 2010Rolf Gebhardt Abstract Wnt/,-catenin signaling has been found to play key roles in metabolic zonation of adult liver, regeneration, and hepatocellular carcinogenesis. In this review, recent progress in this field is summarized, in particular the rapidly growing knowledge about the various interactions of ,-catenin with many transcription factors involved in controlling metabolism. These interactions may provide the basis for understanding how the wide range of activities of Wnt/,-catenin signaling is differentially interpreted. Based on these results, a three-level mode for the molecular interpretation of ,-catenin activity gradients in liver is proposed favoring cell differentiation, metabolic zonation, and proliferation. While derangement of the combinatorial interplay of the various transcription factors with ,-catenin at the intermediary activity level may contribute to the development of metabolic diseases, extremely high activation of ,-catenin may eventually lead to initiation and progression of hepatocellular tumors. Developmental Dynamics 239:45,55, 2010. © 2009 Wiley-Liss, Inc. [source] Real-time observation of Wnt ,-catenin signaling in the chick embryoDEVELOPMENTAL DYNAMICS, Issue 1 2010Anne C. Rios Abstract A critical mediator of cell,cell signaling events during embryogenesis is the highly conserved Wnt family of secreted proteins. Reporter constructs containing multimerized TCF DNA binding sites have been used to detect Wnt ,-catenin dependent activity during animal development. In this report, we have constructed and compared several TCF green fluorescent protein (GFP) reporter constructs. They contained 3, 8, or 12 TCF binding sites upstream of a minimal promoter driving native or destabilized enhanced GFP (EGFP). We have used the electroporation of somites in the chick embryo as a paradigm to test them in vivo. We have verified that they all respond to Wnt signaling in vivo. We have then assessed their efficiency at reflecting the activity of the Wnt pathway. Using destabilized EGFP reporter constructs, we show that somite cells dynamically regulate Wnt/,-catenin,dependent signaling, a finding that was confirmed by performing time-lapse video confocal observation of electroporated embryos. Developmental Dynamics 239:346,353, 2010. © 2009 Wiley-Liss, Inc. [source] Identification of genes expressed preferentially in the developing peripheral margin of the optic cupDEVELOPMENTAL DYNAMICS, Issue 9 2009Jeffrey M. Trimarchi Abstract Specification of the peripheral optic cup by Wnt signaling is critical for formation of the ciliary body/iris. Identification of marker genes for this region during development provides a starting point for functional analyses. During transcriptional profiling of single cells from the developing eye, two cells were identified that expressed genes not found in most other single cell profiles. In situ hybridizations demonstrated that many of these genes were expressed in the peripheral optic cup in both early mouse and chicken development, and in the ciliary body/iris at subsequent developmental stages. These analyses indicate that the two cells probably originated from the developing ciliary body/iris. Changes in expression of these genes were assayed in embryonic chicken retinas when canonical Wnt signaling was ectopically activated by CA-,-catenin. Twelve ciliary body/iris genes were identified as upregulated following induction, suggesting they are excellent candidates for downstream effectors of Wnt signaling in the optic cup. Developmental Dynamics 238:2327,2339, 2009. © 2009 Wiley-Liss, Inc. [source] The role of twist during palate development,DEVELOPMENTAL DYNAMICS, Issue 10 2008Wenli Yu Abstract In palatogenesis, the MEE (Medial Edge Epithelium) cells disappear when palates fuse. We hypothesize that the MEE cells undergo EMT (Epithelial-Mesenchymal Transition) to achieve mesenchyme confluence. Twist has an important role in EMT for tumor metastasis. The purpose of this study was to analyze Twist function during palatal fusion. Twist protein was expressed in palatal shelves and MEE both in vivo and in vitro just prior to fusion. Twist mRNA increased in chicken palates 3 and 6 hr after TGF,3 treatment. Palatal fusion was decreased when cultured palatal shelves were treated with 200 nM Twist siRNA and the subcellular localization of ,-catenin was altered. Twist mRNA decreased in palatal shelves treated with TGF,3 neutralizing antibody or LY294002, a specific phosphatidylinositol-3 kinase (PI-3K) inhibitor. In summary, Twist is downstream of TGF,3 and PI-3K pathways during palatal fusion. However, decreasing Twist with siRNA did not completely block palate fusion, indicating that the function of Twist may be duplicated by other transcription factors. Developmental Dynamics 237:2716,2725, 2008. © 2008 Wiley-Liss, Inc. [source] Novel genes involved in Ciona intestinalis embryogenesis: Characterization of gene knockdown embryosDEVELOPMENTAL DYNAMICS, Issue 7 2007Mayuko Hamada Abstract The sequenced genome of the urochordate ascidian Ciona intestinalis contains nearly 2,500 genes that have vertebrate homologues, but their functions are as yet unknown. To identify novel genes involved in early chordates embryogenesis, we previously screened 200 Ciona genes by knockdown experiments using specific morpholino oligonucleotides and found that suppression of the translation of 40 genes caused embryonic defects (Yamada et al. [2003] Development 130:6485,6495). We have since examined an additional 304 genes, that is, screening 504 genes overall, and a total of 111 genes showed morphological defects when gene function was suppressed. We further examined the role of these genes in the differentiation of six major tissues of the embryo: endoderm, muscle, epidermis, neural tissue, mesenchyme, and notochord. Based on the similarity of phenotypes of gene knockdown embryos, genes were categorized into several groups, with the suggestion that the genes within a given group are involved in similar developmental processes. For example, five were shown to be novel genes that are likely involved in ,-catenin,mediated endoderm formation. The type of large-scale screening used is, therefore, a powerful approach to identify novel genes with significant developmental functions, the details of which will be determined in future studies. Developmental Dynamics 236:1820,1831, 2007. © 2007 Wiley-Liss, Inc. [source] The canonical Wnt signaling pathway plays an important role in lymphopoiesis and hematopoiesisEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 7 2008Frank Abstract The evolutionarily conserved canonical Wnt-,-catenin-T cell factor (TCF)/lymphocyte enhancer binding factor (LEF) signaling pathway regulates key checkpoints in the development of various tissues. Therefore, it is not surprising that a large body of gain-of-function and loss-of-function studies implicate Wnt-,-catenin signaling in lymphopoiesis and hematopoiesis. In contrast, recent papers have reported that Mx-Cre-mediated conditional deletion of ,-catenin and/or its homolog ,-catenin (plakoglobin) did not impair hematopoiesis or lymphopoiesis. However, these studies also report that TCF reporter activity remains active in ,-catenin- and ,-catenin-deficient hematopoietic stem cells and all cells derived from these precursors, indicating that the canonical Wnt signaling pathway was not abrogated. Therefore, these studies in fact show that the canonical Wnt signaling pathway is important in hematopoiesis and lymphopoiesis, even though the molecular basis for the induction of the reporter activity is currently unknown. In this perspective, we provide a broad background to the field with a discussion of the available data and create a framework within which the available and future studies may be evaluated. [source] Novel brain 14-3-3 interacting proteins involved in neurodegenerative diseaseFEBS JOURNAL, Issue 16 2005Shaun Mackie We isolated two novel 14-3-3 binding proteins using 14-3-3 , as bait in a yeast two-hybrid screen of a human brain cDNA library. One of these encoded the C-terminus of a neural specific armadillo-repeat protein, ,-catenin (neural plakophilin-related arm-repeat protein or neurojungin). ,-Catenin from brain lysates was retained on a 14-3-3 affinity column. Mutation of serine 1072 in the human protein and serine 1094 in the equivalent site in the mouse homologue (in a consensus binding motif for 14-3-3) abolished 14-3-3 binding to ,-catenin in vitro and in transfected cells. ,-catenin binds to presenilin-1, encoded by the gene most commonly mutated in familial Alzheimer's disease. The other clone was identified as the insulin receptor tyrosine kinase substrate protein of 53 kDa (IRSp53). Human IRSp53 interacts with the gene product implicated in dentatorubral-pallidoluysian atrophy, an autosomal recessive disorder associated with glutamine repeat expansion of atrophin-1. [source] Androgen receptor function is modulated by the tissue-specific AR45 variantFEBS JOURNAL, Issue 1 2005Isabelle Ahrens-Fath A naturally occurring variant of the human androgen receptor (AR) named AR45 has been identified. It lacks the entire region encoded by exon 1 of the AR gene and is composed of the AR DNA-binding domain, hinge region and ligand-binding domain, preceded by a novel seven amino-acid long N-terminal extension. A survey of human tissues revealed that AR45 was expressed mainly in heart and skeletal muscle. In cotransfection experiments, AR45 inhibited AR function, an effect necessitating intact DNA- and ligand-binding properties. Overexpression of AR45 reduced the proliferation rate of the androgen-dependent LNCaP cells, in line with the repressive effects of AR45 on AR growth-promoting function. AR45 interacted with the AR N-terminal domain in two-hybrid assays, suggesting that AR inhibition was due to the formation of AR,AR45 heterodimers. Under conditions where the transcriptional coactivator TIF2 or the oncogene ,-catenin were overexpressed, AR45 stimulated androgen-dependent promoters in presence of dihydrotestosterone. AR45 activity was triggered additionally by the adrenal androgen androstenedione in presence of exogenous TIF2. Altogether, the data suggest an important role of AR45 in modulating AR function and add a novel level of complexity to the mode of action of androgens. [source] Wnt5a modulates glycogen synthase kinase 3 to induce phosphorylation of receptor tyrosine kinase Ror2GENES TO CELLS, Issue 11 2007Hiroyuki Yamamoto The receptor tyrosine kinase Ror2 plays important roles in mediating non-canonical Wnt5a signaling by activating the Wnt,JNK pathway and inhibiting the ,-catenin,TCF pathway. It has been shown that Ror2 is phosphorylated and activated by casein kinase I, when both molecules are over-expressed in cultured cells. However, it remains unknown whether or not Ror2 is phosphorylated upon Wnt5a stimulation. Here we show that Ror2 is phosphorylated on serine/threonine residues upon stimulation of cultured cells, expressing Ror2 endogenously, with Wnt5a, but not Wnt3a. It was found that treatment of cells with glycogen synthase kinase-3 (GSK-3) inhibitors (LiCl and SB216763) or small interfering RNAs (siRNAs) for GSK-3 (mainly GSK-3,) can inhibit Wnt5a-induced phosphorylation of Ror2. Immunoprecipitated Ror2 can also be phosphorylated by purified GSK-3, or GSK-3,in vitro, and ectopic co-expression of Ror2 and GSK-3 (mainly GSK-3,) in cultured cells results in Ror2 phosphorylation, irrespective of Wnt5a, that is sensitive to SB216763. These results indicate that GSK-3 is involved in Wnt5a-induced phosphorylation of Ror2. Moreover, it was found that Wnt5a-induced cell migration can be inhibited by SB216763 or by siRNA-mediated suppression of GSK-3, (and GSK-3,) expression, further emphasizing the role(s) of GSK-3 in Wnt5a-induced signaling. [source] Wilms tumor genetics: Mutations in WT1, WTX, and CTNNB1 account for only about one-third of tumorsGENES, CHROMOSOMES AND CANCER, Issue 6 2008E. Cristy Ruteshouser Wilms tumor is genetically heterogeneous, and until recently only one Wilms tumor gene was known, WT1 at 11p13. However, WT1 is altered in only ,20% of Wilms tumors. Recently a novel gene, WTX at Xq11.1, was reported to be mutated in Wilms tumors. No overlap between tumors with mutations in WTX and WT1 was noted, suggesting that WT1 and WTX mutations could account for the genetic basis of roughly half of Wilms tumors. To assess the frequency of WTX mutations and their relationship to WT1 mutations in a larger (n = 125) panel of Wilms tumors which had been thoroughly assessed for mutations in WT1, we conducted a complete mutational analysis of WTX that included sequencing of the entire coding region and quantitative PCR to identify deletions of the WTX gene. Twenty-three (18.4%) tumors carried a total of 24 WTX mutations, a lower WTX mutation frequency than that previously observed. Surprisingly, we observed an equivalent frequency of WTX mutations in tumors with mutations in either or both WT1 and CTNNB1 (20.0%) and tumors with no mutation in either WT1 or CTNNB1 (17.5%). WTX has been reported to play a role in the WNT/,-catenin signaling pathway, and, interestingly, WTX deletion/truncation mutations appeared to be rare in tumors carrying exon 3 mutations of CTNNB1, encoding ,-catenin. Our findings indicate that WT1 and WTX mutations occur with similar frequency, that they partially overlap in Wilms tumors, and that mutations in WT1, WTX, and CTNNB1 underlie the genetic basis of about one-third of Wilms tumors. © 2008 Wiley-Liss, Inc. [source] Analysis of somatic APC mutations in rare extracolonic tumors of patients with familial adenomatous polyposis coliGENES, CHROMOSOMES AND CANCER, Issue 2 2004Hendrik Bläker Patients with familial adenomatous polyposis coli (FAP) carry heterozygous mutations of the APC gene. At a young age, these patients develop multiple colorectal adenomas that consistently display a second somatic mutation in the remaining APC wild-type allele. Inactivation of APC leads to impaired degradation of ,-catenin, thereby promoting continuous cell-cycle progression. The role of APC inactivation in rare extracolonic tumors of FAP patients has not been characterized sufficiently. Among tissue specimen from 174 patients with known APC germ-line mutations, we identified 8 tumors infrequently seen in FAP. To investigate the pathogenic role of APC pathway deregulation in these lesions, they were analyzed for second-hit somatic mutations in the mutational cluster region of the APC gene. Immunohistochemistry was performed to compare the expression pattern of ,-catenin to the mutational status of the APC gene. Exon 3 of the ,-catenin gene (CTNNB1) was analyzed for activating mutations to investigate alternative mechanisms of elevated ,-catenin concentration. Although CTNNB1 mutations were not observed, second somatic APC mutations were found in 4 of the 8 tumors: a uterine adenocarcinoma, a hepatocellular adenoma, an adrenocortical adenoma, and an epidermal cyst. These tumors showed an elevated concentration of ,-catenin. No APC mutations were seen in focal nodular hyperplasia of the liver, angiofibrolipoma, and seborrheic wart. This is the first study reporting second somatic APC mutations in FAP-associated uterine adenocarcinoma and epidermal cysts. Furthermore, our data strengthen a role for impaired APC function in the pathogenesis of adrenal and hepatic neoplasms in FAP patients. © 2004 Wiley-Liss, Inc. [source] APC/CTNNB1 (,-catenin) pathway alterations in human prostate cancersGENES, CHROMOSOMES AND CANCER, Issue 1 2002Amy V. Gerstein Genetic alterations serve as beacons for the involvement of specific pathways in tumorigenesis. It was previously shown that 5% of prostate tumors harbor CTNNB1 mutations, suggesting that this tumor type may involve a deregulated APC/CTNNB1 pathway. To explore this possibility further, we searched for mutations in genes implicated in this pathway in 22 samples that included cell lines, xenografts, and primary tumors. We identified seven alterations: two in CTNNB1, three in APC, and two in hTRCP1 (also known as BTRC) which controls the degradation of CTNNB1. Alterations in the CTNNB1 regulatory domain, APC, and hTRCP1 were mutually exclusive, consistent with their equivalent effects on CTNNB1 stability. These results suggest that CTNNB1 signaling plays a critical role in the development of a significant fraction of prostate cancers. Moreover, they provide the first evidence that hTRCP1 plays a role in human neoplasia. © 2002 Wiley-Liss, Inc. [source] Sfrp1, Sfrp2, and Sfrp5 regulate the Wnt/,-catenin and the planar cell polarity pathways during early trunk formation in mouseGENESIS: THE JOURNAL OF GENETICS AND DEVELOPMENT, Issue 2 2008Wataru Satoh The secreted frizzled-related protein gene family encodes proteins that regulate Wnt signaling. Msx1 in situ hybridization of 9.5 days post coitus mouse embryos showing normal neural tube development in an Sfrp1; Sfrp2 double mutant (left) but severe neural tube defects in a Looptail (Lp/+); Sfrp1; Sfrp2 triple mutant (right). These findings suggest that Sfrps regulate the Wnt planar cell polarity pathway. See Satoh et al. in this issue. [source] | |||||||||||||||||||||||||||||||||||||