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Canonical Wnt Signaling (canonical + wnt_signaling)
Terms modified by Canonical Wnt Signaling Selected AbstractsSulindac Inhibits Canonical Wnt Signaling by Blocking the PDZ Domain of the Protein Dishevelled,ANGEWANDTE CHEMIE, Issue 35 2009Ho-Jin Lee Dr. Neuer Nutzen: Der nichtsteroidale Entzündungshemmer Sulindac wechselwirkt direkt und spezifisch mit der PDZ-Domäne des Proteins Dishevelled (Dvl), einer zentralen intrazellulären Komponente des Wnt-Signalwegs. Sulindac bindet an die konventionelle Peptidbindetasche der Domäne (siehe Bild) und könnte durch ihr Blockieren das kanonische Wnt-Signal inhibieren und so einen chemischen Schutz vor Krebs bieten. [source] Effect of canonical Wnt inhibition in the neurogenic cortex, hippocampus, and premigratory dentate gyrus progenitor poolDEVELOPMENTAL DYNAMICS, Issue 7 2008Nina Solberg Abstract Canonical Wnt signaling is crucial for the correct development of both cortical and hippocampal structures in the dorsal telencephalon. In this study, we examined the role of the canonical Wnt signaling in the dorsal telencephalon of mouse embryos at defined time periods by inhibition of the pathway with ectopic expression of Dkk1. Transgenic mice with the D6-driven Dkk1 gene exhibited reduced canonical Wnt signaling in the cortex and hippocampus. As a result, all hippocampal fields were reduced in size. Neurogenesis in the dentate gyrus was severely reduced both in the premigratory and migratory progenitor pool. The lower number of progenitors in the dentate gyrus was not rescued after migration to the subgranular zone and thus the dentate gyrus lacked the entire internal blade and a part of the external blade from postnatal to adult stages. Developmental Dynamics 237:1799,1811, 2008. © 2008 Wiley-Liss, Inc. [source] Developmental phenotypes and reduced Wnt signaling in mice deficient for pygopus 2GENESIS: THE JOURNAL OF GENETICS AND DEVELOPMENT, Issue 5 2007Boan Li Abstract Canonical Wnt signaling involves complex intracellular events culminating in the stabilization of ,-catenin, which enters the nucleus and binds to LEF/TCF transcription factors to stimulate gene expression. Pygopus was identified as a genetic modifier of Wg (Wnt homolog) signaling in Drosophila, and encodes a PHD domain protein that associates with the ,-catenin/LEF/TCF complex. Two murine pygopus paralogs, mpygo1 and mpygo2, have been identified, but their roles in development and Wnt signaling remain elusive. In this study, we report that ablation of mpygo2 expression in mice causes defects in morphogenesis of both ectodermally and endodermally derived tissues, including brain, eyes, hair follicles, and lung. However, no gross abnormality was observed in embryonic intestine. Using a BAT-gal reporter, we found Wnt signaling at most body sites to be reduced in the absence of mpygo2. Taken together, our studies show for the first time that mpygo2 deletion affects embryonic development of some but not all Wnt-requiring tissues. genesis 45:318,325, 2007. © 2007 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] Blocking Dishevelled signaling in the noncanonical Wnt pathway in sea urchins disrupts endoderm formation and spiculogenesis, but not secondary mesoderm formationDEVELOPMENTAL DYNAMICS, Issue 7 2009Christine A. Byrum Abstract Dishevelled (Dsh) is a phosphoprotein key to beta-catenin dependent (canonical) and beta-catenin independent (noncanonical) Wnt signaling. Whereas canonical Wnt signaling has been intensively studied in sea urchin development, little is known about other Wnt pathways. To examine roles of these beta-catenin independent pathways in embryogenesis, we used Dsh-DEP, a deletion construct blocking planar cell polarity (PCP) and Wnt/Ca2+ signaling. Embryos overexpressing Dsh-DEP failed to gastrulate or undergo skeletogenesis, but produced pigment cells. Although early mesodermal gene expression was largely unperturbed, embryos exhibited reduced expression of genes regulating endoderm specification and differentiation. Overexpressing activated beta-catenin failed to rescue Dsh-DEP embryos, indicating that Dsh-DEP blocks endoderm formation downstream of initial canonical Wnt signaling. Because Dsh-DEP-like constructs block PCP signaling in other metazoans, and disrupting RhoA or Fz 5/8 in echinoids blocks subsets of the Dsh-DEP phenotypes, our data suggest that noncanonical Wnt signaling is crucial for sea urchin endoderm formation and skeletogenesis. Developmental Dynamics 238:1649,1665, 2009. © 2009 Wiley-Liss, Inc. [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] Origin matters: Differences in embryonic tissue origin and Wnt signaling determine the osteogenic potential and healing capacity of frontal and parietal calvarial bonesJOURNAL OF BONE AND MINERAL RESEARCH, Issue 7 2010Natalina Quarto Abstract Calvarial bones arise from two embryonic tissues, namely, the neural crest and the mesoderm. In this study we have addressed the important question of whether disparate embryonic tissue origins impart variable osteogenic potential and regenerative capacity to calvarial bones, as well as what the underlying molecular mechanism(s). Thus, by performing in vitro and in vivo studies, we have investigated whether differences exist between neural crest,derived frontal and paraxial mesodermal,derived parietal bone. Of interest, our data indicate that calvarial bone osteoblasts of neural crest origin have superior potential for osteogenic differentiation. Furthermore, neural crest,derived frontal bone displays a superior capacity to undergo osseous healing compared with calvarial bone of paraxial mesoderm origin. Our study identified both in vitro and in vivo enhanced endogenous canonical Wnt signaling in frontal bone compared with parietal bone. In addition, we demonstrate that constitutive activation of canonical Wnt signaling in paraxial mesodermal,derived parietal osteoblasts mimics the osteogenic potential of frontal osteoblasts, whereas knockdown of canonical Wnt signaling dramatically impairs the greater osteogenic potential of neural crest,derived frontal osteoblasts. Moreover, fibroblast growth factor 2 (FGF-2) treatment induces phosphorylation of GSK-3, and increases the nuclear levels of ,-catenin in osteoblasts, suggesting that enhanced activation of Wnt signaling might be mediated by FGF. Taken together, our data provide compelling evidence that indeed embryonic tissue origin makes a difference and that active canonical Wnt signaling plays a major role in contributing to the superior intrinsic osteogenic potential and tissue regeneration observed in neural crest,derived frontal bone. © 2010 American Society for Bone and Mineral Research [source] Enhanced Chondrogenesis and Wnt Signaling in PTH-Treated Fractures,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 12 2007Sanjeev Kakar Abstract Studies have shown that systemic PTH treatment enhanced the rate of bone repair in rodent models. However, the mechanisms through which PTH affects bone repair have not been elucidated. In these studies we show that PTH primarily enhanced the earliest stages of endochondral bone repair by increasing chondrocyte recruitment and rate of differentiation. In coordination with these cellular events, we observed an increased level of canonical Wnt-signaling in PTH-treated bones at multiple time-points across the time-course of fracture repair, supporting the conclusion that PTH responses are at least in part mediated through Wnt signaling. Introduction: Since FDA approval of PTH [PTH(1,34); Forteo] as a treatment for osteoporosis, there has been interest in its use in other musculoskeletal conditions. Fracture repair is one area in which PTH may have a significant clinical impact. Multiple animal studies have shown that systemic PTH treatment of healing fractures increased both callus volume and return of mechanical competence in models of fracture healing. Whereas the potential for PTH has been established, the mechanism(s) by which PTH produces these effects remain elusive. Materials and Methods: Closed femoral fractures were generated in 8-wk-old male C57Bl/6 mice followed by daily systemic injections of either saline (control) or 30 ,g/kg PTH(1,34) for 14 days after fracture. Bones were harvested at days 2, 3, 5, 7, 10, 14, 21, and 28 after fracture and analyzed at the tissue level by radiography and histomorphometry and at the molecular and biochemical levels level by RNase protection assay (RPA), real-time PCR, and Western blot analysis. Results: Quantitative ,CT analysis showed that PTH treatment induced a larger callus cross-sectional area, length, and total volume compared with controls. Molecular analysis of the expression of extracellular matrix genes associated with chondrogenesis and osteogenesis showed that PTH treated fractures displayed a 3-fold greater increase in chondrogenesis relative to osteogenesis over the course of the repair process. In addition, chondrocyte hypertrophy occurred earlier in the PTH-treated callus tissues. Analysis of the expression of potential mediators of PTH actions showed that PTH treatment significantly induced the expression of Wnts 4, 5a, 5b, and 10b and increased levels of unphosphorylated, nuclear localized ,-catenin protein, a central feature of canonical Wnt signaling. Conclusions: These results showed that the PTH-mediated enhancement of fracture repair is primarily associated with an amplification of chondrocyte recruitment and maturation in the early fracture callus. Associated with these cellular effects, we observed an increase in canonical Wnt signaling supporting the conclusion that PTH effects on bone repair are mediated at least in part through the activation of Wnt-signaling pathways. [source] miR-29 suppression of osteonectin in osteoblasts: Regulation during differentiation and by canonical Wnt signalingJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 1 2009Kristina Kapinas Abstract The matricellular protein osteonectin, secreted protein acidic and rich in cysteine (SPARC, BM-40), is the most abundant non-collagenous matrix protein in bone. Matricellular proteins play a fundamental role in the skeleton as regulators of bone remodeling. In the skeleton, osteonectin is essential for the maintenance of bone mass and for balancing bone formation and resorption in response to parathyroid hormone (PTH). It promotes osteoblast differentiation and cell survival. Mechanisms regulating the expression of osteonectin in the skeleton and in other tissues remain poorly understood. We found that the proximal region of the mouse osteonectin 3, untranslated region (UTR) contains a well-conserved, dominant regulatory motif that interacts with microRNAs (miRs)-29a and -29c. Transfection of osteoblastic cells with miR-29a inhibitors increased osteonectin protein levels, whereas transfection of miR-29a precursor RNA decreased osteonectin. miR-29a and -29c were increased during osteoblastic differentiation in vitro. The up-regulation of these miRNAs correlated with decreased osteonectin protein during the matrix maturation and mineralization phases of late differentiation. In contrast, osteonectin transcript levels remained relatively constant during this process, implying repression of translation. Treatment of osteoblasts with LiCl induced miR-29a and -29c expression and decreased osteonectin synthesis. When cells were treated with Dickkopf-1 (Dkk-1), miR-29a and -29c expression was repressed. These data suggest that canonical Wnt signaling, which is increased during osteoblastic differentiation, induces expression of miR-29. Osteonectin and miR-29 are co-expressed in extra-skeletal tissues, and the post-transcriptional mechanisms regulating osteonectin in osteoblasts are likely to be active in other cell systems. J. Cell. Biochem. 108: 216,224, 2009. © 2009 Wiley-Liss, Inc. [source] Oxysterol-induced osteogenic differentiation of marrow stromal cells is regulated by Dkk-1 inhibitable and PI3-kinase mediated signalingJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 2 2008Christopher M. Amantea Abstract Osteoporosis and its complications cause morbidity and mortality in the aging population, and result from increased bone resorption by osteoclasts in parallel with decreased bone formation by osteoblasts. A widely accepted strategy for improving bone health is targeting osteoprogenitor cells in order to stimulate their osteogenic differentiation and bone forming properties through the use of osteoinductive/anabolic factors. We previously reported that specific naturally occurring oxysterols have potent osteoinductive properties, mediated in part through activation of hedgehog signaling in osteoprogenitor cells. In the present report, we further demonstrate the molecular mechanism(s) by which oxysterols induce osteogenesis. In addition to activating the hedgehog signaling pathway, oxysterol-induced osteogenic differentiation is mediated through a Wnt signaling-related, Dkk-1-inhibitable mechanism. Bone marrow stromal cells (MSC) treated with oxysterols demonstrated increased expression of osteogenic differentiation markers, along with selective induced expression of Wnt target genes. These oxysterol effects, which occurred in the absence of ,-catenin accumulation or TCF/Lef activation, were inhibited by the hedgehog pathway inhibitor, cyclopamine, and/or by the Wnt pathway inhibitor, Dkk-1. Furthermore, the inhibitors of PI3-Kinase signaling, LY 294002 and wortmanin, inhibited oxysterol-induced osteogenic differentiation and induction of Wnt signaling target genes. Finally, activators of canonical Wnt signaling, Wnt3a and Wnt1, inhibited spontaneous, oxysterol-, and Shh-induced osteogenic differentiation of bone marrow stromal cells, suggesting the involvement of a non-canonical Wnt pathway in pro-osteogenic differentiation events. Osteogenic oxysterols are, therefore, important small molecule modulators of critical signaling pathways in pluripotent mesenchymal cells that regulate numerous developmental and post-developmental processes. J. Cell. Biochem. 105: 424,436, 2008. © 2008 Wiley-Liss, Inc. [source] Wnt 3a promotes proliferation and suppresses osteogenic differentiation of adult human mesenchymal stem cells,JOURNAL OF CELLULAR BIOCHEMISTRY, Issue 6 2004Genevieve M. Boland Abstract Multipotential adult mesenchymal stem cells (MSCs) are able to differentiate along several known lineages, and lineage commitment is tightly regulated through specific cellular mediators and interactions. Recent observations of a low/high bone-mass phenotype in patients expressing a loss-/gain-of-function mutation in LRP5, a coreceptor of the Wnt family of signaling molecules, suggest the importance of Wnt signaling in bone formation, possibly involving MSCs. To analyze the role of Wnt signaling in mesenchymal osteogenesis, we have profiled the expression of WNTs and their receptors, FRIZZLEDs (FZDs), and several secreted Wnt inhibitors, such as SFRPs, and examined the effect of Wnt 3a, as a representative canonical Wnt member, during MSC osteogenesis in vitro. WNT11, FZD6, SFRP2, and SFRP3 are upregulated during MSC osteogenesis, while WNT9A and FZD7 are downregulated. MSCs also respond to exogenous Wnt 3a, based on increased ,-catenin nuclearization and activation of a Wnt-responsive promoter, and the magnitude of this response depends on the MSC differentiation state. Wnt 3a exposure inhibits MSC osteogenic differentiation, with decreased matrix mineralization and reduced alkaline phosphatase mRNA and activity. Wnt 3a treatment of fully osteogenically differentiated MSCs also suppresses osteoblastic marker gene expression. The Wnt 3a effect is accompanied by increased cell number, resulting from both increased proliferation and decreased apoptosis, particularly during expansion of undifferentiated MSCs. The osteo-suppressive effects of Wnt 3a are fully reversible, i.e., treatment prior to osteogenic induction does not compromise subsequent MSC osteogenesis. The results also showed that sFRP3 treatment attenuates some of the observed Wnt 3a effects on MSCs, and that inhibition of canonical Wnt signaling using a dominant negative TCF1 enhances MSC osteogenesis. Interestingly, expression of Wnt 5a, a non-canonical Wnt member, appeared to promote osteogenesis. Taken together, these findings suggest that canonical Wnt signaling functions in maintaining an undifferentiated, proliferating progenitor MSC population, whereas non-canonical Wnts facilitate osteogenic differentiation. Release from canonical Wnt regulation is a prerequisite for MSC differentiation. Thus, loss-/gain-of-function mutations of LRP5 would perturb Wnt signaling and depress/promote bone formation by affecting the progenitor cell pool. Elucidating Wnt regulation of MSC differentiation is important for their potential application in tissue regeneration. Published 2004 Wiley-Liss, Inc. [source] Human homolog of NOTUM, overexpressed in hepatocellular carcinoma, is regulated transcriptionally by ,-catenin/TCFCANCER SCIENCE, Issue 6 2008Yuichi Torisu The Drosophila Notum gene, which is regulated by the Wingless pathway, encodes a secreted hydrolase that modifies heparan sulfate proteoglycans. In comparative analysis of the gene expression profiles in primary human hepatocellular carcinomas (HCC) and normal organs, we observed that the human ortholog of Drosophila Notum was overexpressed markedly in a subset of HCC, but expressed rarely in adult normal tissues. Immunoblotting confirmed the overexpression of NOTUM protein in 12 of 40 primary HCC cases (30%). High levels of NOTUM protein were significantly associated with intracellular (nuclear or cytoplasmic) accumulation of ,-catenin protein: all 10 HCC with high intracellular ,-catenin also had high NOTUM expression, whereas only 2 of 30 cases (6.7%) without intracellular ,-catenin had high NOTUM expression (P < 0.00001). NOTUM expression in HepG2 cells was downregulated significantly by induction of a dominant-negative mutant of TCF4, a ,-catenin partner. In vivo binding of the ,-catenin/TCF complex to the NOTUM promoter was demonstrated by chromatin immunoprecipitation in HepG2 and SW480 cells, where canonical Wnt signaling is activated constitutively. These findings provide evidence that NOTUM is a novel target of ,-catenin/TCF4 and is upregulated in Wnt/,-catenin signaling-activated HCC. (Cancer Sci 2008; 99: 1139,1146) [source] | |||||||||||||